JP2004191953A - Optical scanning device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a geometric characteristic of the elastically deforming part of a vibrating body in an optical scanning device 1 which scans with light by varying the reflection direction of light which is made incident to a reflection mirror part by vibrating at least a part of the vibrating body 5 having the reflection mirror part 8. <P>SOLUTION: The vibrating body 5 includes (a) first spring parts 8 and 9 which are connected to the reflection mirror part 8 and on which spring parts a torsional vibration is generated, (b) a plurality of second spring parts 12, 13, 15 and 16 which are connected to the first spring parts and branchedly connected to a fixed frame part 7 of the vibrating body at a branching distance broader than the width of the first spring part and on which spring parts a bending vibration and a torsional vibration are generated, and (c) vibrating sources a, b, c, and d which vibrate the respective second spring parts, and the second geometrical moment of inertia of an elastically deforming part, composed of the respective second spring parts and driving sources which correspond to each other, of the vibrating body, is smaller than the geometrical moment of inertia of the first spring parts. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an optical scanning device that scans light by vibrating at least a part of a vibrating body having a reflection mirror unit to change a reflection direction of light incident on the reflection mirror unit and scan light. The present invention relates to a technique for improving a geometric characteristic of an elastically deformable portion of a body.

  2. Description of the Related Art Conventionally, an optical scanning device has been used for an image forming apparatus such as a laser printer, a projection device that scans a laser beam and projects an image. As a type of the optical scanning device, there are generally a one-way rotation type represented by a polygon mirror and a swing type represented by a galvanometer mirror. It is said that the swing type optical scanning device can be easily reduced in size, weight, and cost as compared with the one-direction rotation type optical scanning device.

  One conventional example of an oscillating optical scanning device is an optical scanning device in which at least a part of a vibrating body having a reflecting mirror portion is vibrated to change the reflection direction of light incident on the reflecting mirror portion and scan light. Device.

  In this conventional example, the vibrating body is configured to include a reflecting mirror, a fixed frame, and an elastically deforming portion connected to the reflecting mirror and the fixed frame. This conventional example is further configured to include a drive source that generates torsional vibration in the elastically deformable portion.

  Conventionally, a galvano scanner that scans light by vibrating a galvanometer mirror using a resonance phenomenon has been known. In this conventional galvano scanner, as a driving method for generating resonance, there is a method using electrostatic, electromagnetic force, heat, piezoelectric, or the like. Patent Document 1 describes a driving method of an optical scanning device using longitudinal vibration of a piezoelectric element as a conventional example.

  In this conventional example, an elastic supporting frame, an elastically deformable portion, and a reflecting mirror portion are mutually coupled and integrally formed on the same plane. Two piezoelectric elements are mounted on one of both surfaces of the support frame so as to have a relative positional relationship symmetrical with respect to the position of the reflection mirror. These two piezoelectric elements are vibrated in opposite phases to each other, and the vibration is transmitted to the elastically deformable portion via the support frame. Thereby, torsional vibration is generated in the elastically deforming portion, and the torsional vibration causes the reflecting mirror portion to swing around the swing axis.

  Patent Literature 2 discloses another conventional example of an optical scanning device. In this conventional example, the swing axis of the reflecting mirror is set at a position offset from the center of gravity of the reflecting mirror, and the translational vibration of one piezoelectric element is transmitted to the reflecting mirror via the support. Thereby, torsional vibration is induced in the reflection mirror.

  Patent Document 3 describes, as a conventional example, an optical scanning device configured to include a vibrating unit, a scanning unit on which a reflecting mirror is mounted, and a beam-shaped elastic deformation unit. In this conventional example, the fixed end of the elastically deforming portion is fixed to the vibrating portion, and the free end is fixed to the scanning portion. A piezoelectric element is mounted on the vibration unit, and the piezoelectric element applies vibration of a type corresponding to the elastic vibration mode of the elastic deformation unit to the vibration unit. Due to the vibration, the reflection mirror is vibrated, and the light reflected from the reflection mirror is scanned.

Patent Document 4 describes still another conventional example of an optical scanning device. In this conventional example, a mirror section is connected to a first frame section via a first spring section. The first frame is connected to the second frame via a second spring. A connecting portion is formed integrally with the second frame portion, and a plurality of piezoelectric bimorphs are connected to the connecting portion and the third frame portion at both ends.
JP 2001-272626 A Japanese Patent No. 3129219 Japanese Patent No. 2981576 JP-A-10-253912

  In this conventional example, a pair of piezoelectric bimorphs symmetrical to each other with respect to the connection portion are bent and vibrated in opposite phases. The bending vibration is converted into torsional vibration of the second frame portion by the connecting portion. The torsional vibration eventually swings the mirror section.

  In this type of optical scanning device, the oscillation frequency of the reflection mirror means the scanning frequency of the reflected light from the reflection mirror, and the swing angle of the reflection mirror means the scanning angle of the reflected light. In this type of optical scanning device, an increase in the scan angle and an increase in the scan frequency are in conflict with each other, but there is a strong demand for increasing the scan frequency as much as possible while securing the scan angle. .

  On the other hand, in this type of optical scanning device, when the geometric characteristics (for example, dimensions, orientation, relative positional relationship with peripheral elements, etc.) of the elastically deformable portion are changed, the vibration characteristics (for example, vibration Ease, durability, etc.) also change.

  In view of the circumstances described above, the present invention provides an optical scanning device that scans light by vibrating at least a part of a vibrating body having a reflection mirror unit to change the reflection direction of light incident on the reflection mirror unit. The object of the present invention is to improve the geometric characteristics of the elastically deformable portion of the vibrating body.

  The following aspects are obtained by the present invention. Each mode is divided into sections, each section is numbered, and described in a format in which the numbers of other sections are cited as necessary. This is to facilitate understanding of some of the technical features that can be adopted by the present invention and combinations thereof, and the technical features that can be adopted by the present invention and combinations thereof are limited to the following embodiments. Should not be interpreted as That is, it should be construed that the technical features not described in the following embodiments but described in the present specification can be appropriately extracted and adopted as the technical features of the present invention.

  Furthermore, listing each section in a form that quotes the number of the other section does not necessarily prevent the technical features described in each section from being separated from and independent of the technical features described in the other sections. It is to be construed that the technical features described in the respective sections can be appropriately made independent according to their properties.

(1) An optical scanning device that scans light by vibrating at least a part of a vibrating body having a reflection mirror unit to change a reflection direction of light incident on the reflection mirror unit,
The vibrator,
A first spring unit connected to the reflection mirror unit and generating torsional vibration;
The first spring portion is connected to the fixed frame portion of the vibrating body at a branch interval wider than the width of the first spring portion, and bending vibration and torsional vibration are generated. A plurality of second spring portions,
A plurality of driving sources for respectively oscillating the plurality of second springs;
An optical scanning device in which, among the vibrators, a second moment of area in an elastically deformable portion composed of each of the second spring portions and each of the driving sources corresponding to each other is smaller than the second moment of area of the first spring portion.

  In this device, the vibrating body is configured such that the reflecting mirror portion and the fixed frame portion are not connected to each other only by the first spring portion, but the first spring portion and the plurality of second springs extending therefrom. And are connected to each other.

  Further, in this device, the plurality of second spring portions are connected to the first spring portion in a state where the plurality of second spring portions branch off from the first spring portion at an interval wider than the width of the first spring portion. Thereby, the geometrical characteristics of the plurality of second spring portions corresponding to the elastically deformable portions of the vibrating body are appropriate in relation to the first spring portions corresponding to other portions of the same vibrating body. Be converted to

  Furthermore, in this device, not only torsional vibration but also bending vibration is generated in the plurality of second spring portions. That is, the plurality of second spring portions are elastically deformed in a state where the degree of freedom regarding the shape change is high.

  Therefore, according to this device, the load required to vibrate the reflection mirror unit is reduced by the first spring unit as compared with the case where the connection between the reflection mirror unit and the fixed frame unit is performed only by the first spring unit. And a plurality of second spring portions.

  As a result, according to this device, it is easy to reduce the load that must be received by the first spring to vibrate the reflection mirror. For example, it is easy to reduce the torsion of the first spring portion and to ease the stress concentration at the connection portion between the first spring portion and another portion.

  Further, according to this device, it is easy to reduce the load that each second spring portion must receive to vibrate the reflection mirror portion. For example, it is easy to reduce the torsion of each second spring portion, and to ease the stress concentration at the connection portion between each second spring portion with the first spring portion and the connection portion with the fixed frame portion. Become.

  Therefore, according to this device, compared to the case where the connection between the reflection mirror section and the fixed frame section is performed only by the first spring section, the first spring can be applied to a small load for the degree of vibration of the reflection mirror section. It is sufficient that the portion and the plurality of second spring portions respectively bear.

  As a result, according to this device, a high demand for vibration of the reflection mirror portion, such as compatibility between an increase in the scanning angle of the reflected light and an increase in the scanning frequency, is realized with high durability of the vibrating body. It becomes easier.

  Further, in this device, of the vibrating body, the elastically deforming portion composed of the corresponding second spring portions and the respective driving sources, and the first spring portion are different from each other with respect to the second moment of area. Have been. Specifically, the second moment of area of the elastic deformation portion is smaller than the second moment of area of the first spring portion.

  In general, the smaller the second moment of area of a member, the lower the bending stiffness and the torsional stiffness of the member, and therefore the amount of elastic deformation of the member in response to the same input to the member tends to increase. .

  Therefore, according to this optical scanning device, the elastically deformable portion is more likely to be elastically deformed than when the second moment of area of the elastically deformable portion is greater than or equal to the second moment of area of the first spring portion. It becomes easy to increase the scanning angle of the mirror unit. Thereby, the geometrical characteristics of the plurality of second spring portions corresponding to the elastically deformable portions of the vibrating body are appropriate in relation to the first spring portions corresponding to other portions of the same vibrating body. Be converted to According to this optical scanning device, for example, it is easy to realize a large scanning angle for power consumption.

  The “branch interval” in this section and each of the following sections can be interpreted to mean a distance between outer edges of the plurality of second spring portions, for example, as indicated by “L2” in FIG. is there. Further, although not shown, it can also be interpreted to mean the interval between a plurality of center lines that respectively penetrate the plurality of second spring portions in the longitudinal direction. Further, although not shown, it can be interpreted to mean the interval between the inner edges of the plurality of second spring portions.

(2) An optical scanning device which scans light by vibrating at least a part of a vibrating body having a reflection mirror unit to change a reflection direction of light incident on the reflection mirror unit.
The vibrator,
A first spring unit connected to the reflection mirror unit and generating torsional vibration;
The first spring portion is connected to the fixed frame portion of the vibrating body at a branch interval wider than the width of the first spring portion, and bending vibration and torsional vibration are generated. A plurality of second spring portions, and
Each of the second spring portions has the same elastic modulus as the first spring portion, but has a cross-sectional shape that is more easily elastically deformed than the first spring portion,
The optical scanning device further includes a driving source that vibrates the plurality of second springs.

  In this device, each second spring portion has the same elastic coefficient as the first spring portion, but has a cross-sectional shape that is more easily elastically deformed than the first spring portion. Therefore, in this device, each second spring portion has a mechanical property that is more easily elastically deformed than the first spring portion.

  Therefore, according to this device, the second spring portion has a mechanical property that is less likely to be elastically deformed than the first spring portion, according to the principle basically common to the device according to the above item (1). Then, the second spring portion is easily elastically deformed, so that it is easy to increase the scanning angle of the reflection mirror portion. According to this optical scanning device, for example, it is easy to realize a large scanning angle for power consumption.

(3) The optical scanning device according to (1) or (2), wherein the branch interval does not exceed the width of the reflection mirror unit.

  Japanese Patent Application Laid-Open No. 10-104543 describes a conventional example of a resonance-type optical scanning device that vibrates a reflection mirror unit using a resonance phenomenon. This conventional example includes a vibrating body configured to include a movable portion, a fixed portion, and a beam portion connecting the movable portion and the fixed portion to each other. A mirror surface is formed on the movable part. On the other hand, a piezoelectric element is mounted on the fixed part, and when the vibrating body is vibrated by the piezoelectric element, the mirror surface is vibrated together with the movable part, whereby the light reflected from the mirror surface is scanned. You.

  In this conventional example, the mirror surface is swung by vibrating the vibrating body at the frequency of the resonance vibration mode of the vibrating body. Further, in this conventional example, in order to scan the reflected light from the mirror surface at high speed, the vibrating body is made to vibrate using a higher-order resonance vibration mode of the vibrating body.

  However, in this conventional example, since the higher-order vibration mode of the vibrating body is used, the vibration frequency of the vibrating body is set high. Therefore, optical scanning at high speed is possible, but stable optical scanning has been difficult due to the overlap of unnecessary higher-order vibration modes and the entry of disturbance.

  Further, in this conventional example, since a higher-order vibration mode of the vibrating body is used, it is necessary to reduce the rigidity of the spring portion as the elastic deformation portion in order to secure the amplitude of the vibrating body. Therefore, the vibrating body tends to be easily damaged.

  On the other hand, in the resonance type optical scanning device, it is important to stabilize the straightness of the reflected light from the reflecting mirror portion, that is, the scanning light.

  On the other hand, the literature "Consideration on the practical application of two-dimensional micro magnetic scanner" Hiroyuki, December 22, 2001, p. 39-44), a high-speed, large-amplitude optical scanning is practically used in a micromagnetic scanner in which a reflecting mirror is formed on a vibrating body supported by a doubly supported beam. A conventional technique for converting the data is described.

  According to this conventional technique, the resonance frequency of the torsional resonance mode of the vibrating body is made lower than the resonance frequencies of other vibration modes (for example, vertical translation resonance mode, horizontal translation resonance mode, rotation resonance mode, tilt resonance mode, etc.). Can be

  However, according to this conventional technique, if the resonance frequency of the torsional resonance mode is made lower than the resonance frequencies of the other vibration modes in order to stabilize the straightness of the scanning light, the torsional resonance frequency decreases. Therefore, when this conventional technique is employed, it is difficult to realize high-speed optical scanning.

  The present inventors have conducted various studies with the aim of improving the straightness of scanning light by performing numerical analysis, which will be described in detail later. As a result, the present inventors have obtained the following findings.

  That is, the optical scanning device may be configured such that the branch interval between the plurality of second spring portions does not exceed the width of the reflection mirror portion after adopting the configuration of the vibrating body in the above item (1) or (2). For example, among a plurality of types of vibration modes that can be generated in a vibrating body, in a frequency range lower than the natural frequency of the required vibration mode, the vertical vibration mode or the horizontal vibration mode that is an unnecessary vibration mode, Among them, they found that the generation of higher-order ones was suppressed.

  If the branch interval is set in this manner, the natural frequency of the torsional vibration mode is greatly separated from the natural frequency of the other vibration modes. No overlap occurs, and the straightness of the scanning light is improved.

  Further, if the branch interval is set in this manner, when the vibrating body is vibrated at a high frequency and a large scanning angle, an unnecessary vibration mode is generated or the vibrating body is overlapped with the unnecessary vibration mode due to an unnecessary vibration mode. Is less likely to be damaged.

  Based on the findings described above, in the optical scanning device according to this item, the branch interval of the plurality of second spring portions is reflected after the configuration of the vibrator in the above item (1) or (2) is adopted. The width of the mirror is not exceeded.

(4) The optical scanning device according to any one of (1) to (3), wherein the plurality of second spring portions generate bending vibration in a plane parallel to each plate thickness direction.

(5) The optical scanning device according to (4), wherein the plurality of second spring portions generate bending vibrations in mutually opposite phases.

  According to this device, since each bending vibration is generated in the plurality of second spring portions in a state where the torsional vibration of the first spring portion converted from each bending vibration is strengthened mutually, the deflection of the reflection mirror portion is generated. It is easy to increase the angle, that is, the scan angle.

(6) The optical scanning device according to (5), wherein the plurality of second spring portions generate bending vibrations in opposite phases to each other by a mechanical force.

(7) The optical scanning device according to (6), wherein the drive source is mounted on at least one of the plurality of second spring portions, which is a target spring portion.

(8) The optical scanning device according to (7), wherein the drive source is fixed to a target surface that is at least one of both surfaces of the target spring portion.

(9) The drive source is fixed to the target surface in a posture that straddles the target surface and one of the two surfaces of the fixed frame portion adjacent to the target spring portion corresponding to the target surface. The optical scanning device according to item (8).

  The device according to the above mode (8) can be implemented in a mode in which the drive source is fixed to the target surface in a posture that does not reach the fixed frame portion. However, when this mode is adopted, the vibrating body is not necessarily vibrated in a state where the node of vibration is stably located at the connection point between the second spring portion and the fixed frame portion.

  On the other hand, in the device according to this aspect, the drive source is fixed to the target surface in a posture reaching the fixed frame portion. Therefore, according to this device, the vibrating body is vibrated in a state where the node of vibration of the vibrating body is stably located at the connection point between the second spring portion and the fixed frame portion.

  Therefore, according to this device, the vibrating body is placed in a state where the node of vibration of the vibrating body is located at a position shifted toward the second spring portion from the connection point between the second spring portion and the fixed frame portion. Unlike the case where the vibrating body is vibrated, the vibration state of the vibrating body is stabilized.

  Further, according to this device, the entire second spring portion can be involved in the occurrence of bending deformation and torsional deformation. Therefore, according to this device, by effectively utilizing the entire second spring portion, it becomes easy to efficiently transmit the vibration of the drive source to the second spring portion. Therefore, according to this device, it is easy to realize a large scanning angle by the vibration of the same driving source.

  It should be noted that the technical features described in this section, that is, the feature of arranging the drive source so as to positionally correspond to the nodes of vibration, are separated from the technical features described in the preceding other sections. Can be implemented.

(10) The optical scanning device according to (8) or (9), wherein the driving source is fixed to the target surface by a thin film forming method.

  According to this device, the drive source can be mounted on the target surface without using an adhesive. Therefore, according to this device, the drive source can be integrally and firmly attached to the target surface without the interposition of the adhesive layer.

  Therefore, according to this device, it is not necessary to worry about the problem of displacement and separation caused by the interposition of the adhesive layer between the driving source and the target surface, and it is easy to stabilize the vibration of the vibrating body. Become.

(11) The optical scanning device according to (10), wherein the thin film forming method is any one of CVD, sputtering, hydrothermal synthesis, sol-gel, and fine particle spraying.

  As used herein, "CVD" is a chemical vapor deposition technique for depositing a layer or film on the surface of a substrate by a gas-solid or gas-liquid chemical reaction. Sputtering is a technique for depositing a layer or film on the surface of a substrate by electrical discharge in a vacuum. Hydrothermal synthesis is a technique for forming a film by crystallizing ions in an aqueous solution at high temperature and high pressure. Fine particle spraying is a technique in which ultrafine particles mixed with a gas are accelerated and sprayed onto a substrate through a fine nozzle to form a coating.

(12) The optical scanning device according to any one of (7) to (11), wherein the drive source extends along the target spring portion and is expanded and contracted in the extending direction.

(13) The optical scanning device according to (2), wherein the drive source directly vibrates the vibrator.

(14) The optical scanning device according to (2), wherein the driving source indirectly vibrates the vibrating body.

(15) The optical scanning device according to any one of (1) to (14), wherein the drive source vibrates the vibrating body at the same frequency as its resonance frequency.

  According to this device, since the vibrating body is oscillated in a vibrationally stable state due to the vibrating body being in a resonance state, stable optical scanning can be easily performed.

(16) The reflection mirror section is caused to swing around a swing axis by the torsional vibration,
The vibrating body further includes a connecting portion that connects the first spring portion and the plurality of second spring portions to each other, and the first spring portion, the plurality of second spring portions, and the connecting portion. And constitute a connected body,
(1) The connecting body is disposed at two opposing positions of the vibrating body that oppose each other in the direction of the oscillation axis with the reflection mirror section interposed therebetween. Optical scanning device.

  According to this device, the reflection mirror is vibrated on both sides of the reflection mirror by the two coupling bodies opposed to each other with the reflection mirror interposed therebetween, so that the reflection mirror is vibrated only on one side. In addition, it is easy to stabilize the angle of the reflection surface of the reflection mirror section.

  It should be noted that the term “connecting portion” in this section and each of the following sections may be defined as, for example, a part of the second spring portion of the connecting body to which the connecting portion belongs, or may be defined as the connecting portion. Can also be defined as constituting a part of the first spring portion in the connected body to which.

  Further, the technical features described in this section, that is, the opposing arrangement of the spring portions can be implemented separately from the technical features described in the other preceding sections.

(17) The optical scanning device according to the mode (16), wherein the two coupled bodies respectively arranged at the two opposing positions are arranged symmetrically with respect to the position of the reflection mirror unit.

(18) The vibrating body further includes a connecting portion that connects the first spring portion and the plurality of second spring portions to each other, and the drive source is not attached to the connecting portion (1). The optical scanning device according to any one of the above items (17) to (17).

  In this device, bending vibration and torsional vibration of the second spring portion are transmitted to the first spring portion as torsional vibration via the connecting portion. The connecting portion performs its vibration transmitting function by its elastic deformation. In this device, a drive source is not mounted on a connecting portion that performs such a vibration transmitting function.

  Therefore, according to this device, the possibility that the driving source inhibits the elastic deformation of the connecting portion is reduced as compared with the case where the driving source is mounted on the connecting portion. Therefore, according to this device, the driving source does not have to be disposed at a position where the scanning angle of the reflection mirror section is sacrificed.

(19) The vibrating body further includes a connecting portion that connects the first spring portion and the plurality of second spring portions to each other, and the connecting portion includes the first spring portion and the second spring portion. The optical scanning device according to any one of (1) to (18), wherein the optical scanning device is connected to the plurality of second spring portions at substantially right angles.

  According to this device, for example, a design for giving a desired vibration characteristic to the vibrating body is compared with a case where the connecting portion is obliquely connected to the first spring portion and each of the second spring portions. It doesn't have to be complicated.

  On the other hand, focusing only on the bending deformation among the deformations of the second spring portions, a transition from a state in which each second spring portion and the connecting portion are connected at right angles to a state in which they are connected in series with each other. Accordingly, the tendency of the bending deformation of each second spring portion to depend on the expansion and contraction of the connecting portion increases, so that the tendency of the second spring portion to be inhibited by the connecting portion increases.

  On the other hand, according to the device according to this aspect, since each second spring portion and the connection portion are connected to each other substantially at a right angle, bending deformation of the deformation of each second spring portion is reduced at the connection portion. Without being disturbed.

  It should be noted that the technical features described in this section, that is, the orthogonal arrangement of the spring portions can be implemented separately from the technical features described in other preceding sections.

(20) An image forming apparatus which forms an image by scanning a light beam,
A light source for emitting the light beam;
(1) An image forming apparatus comprising: the optical scanning device according to any one of (1) to (19); and a scanning unit that scans a light beam emitted from the light source by using the optical scanning device.

  In this image forming apparatus, scanning of a light beam for forming an image is performed by using an optical scanning device that can easily achieve both a high scanning frequency and a large scanning angle.

(21) The scanning unit performs a first scan that scans the light beam in a first direction and a second scan that scans in a second direction intersecting the first direction at a lower speed than the first scan. The image forming apparatus according to (20), wherein the optical scanning device is used for performing the first scanning.

  In this image forming apparatus, of the two types of scanning performed by the scanning unit, the one requiring a higher scanning speed is performed using the optical scanning device. Therefore, according to this image forming apparatus, one of the two types of scanning, which is more appropriate to use the optical scanning device for improving the performance, is selected, and the optical scanning device is selected for the selected type of scanning. Is used.

(22) The image forming apparatus according to (20) or (21), further including an optical system that guides a light beam scanned by the scanning unit toward a retina of an observer.

  Hereinafter, some of the more specific embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a retinal scanning type image forming apparatus 100 including an optical scanning device 1 according to a first embodiment of the present invention as a whole in a systematic manner and partially in a block diagram. .

  As shown in FIG. 1, an image forming apparatus 100 including an optical scanning device 1 is configured to project an image directly on a retina of an observer, and is used by being mounted on a head of the observer. It is a type of display device.

  As shown in FIG. 1, the image forming apparatus 100 includes a light source unit 101, and a vertical scanning system 102 and a horizontal scanning system 103 as scanning units. The image forming apparatus 100 further includes relay optical systems 126 and 127, a collimating lens 122, and a beam detector 123 (this is an example of an optical sensor).

  As shown in FIG. 1, the light source unit 101 includes a video signal supply circuit 104, a light source drive circuit 105 connected to the video signal supply circuit 104, and a light source 106 driven by the light source drive circuit 108. ing. The light source unit 101 further includes a collimating optical system 107, dichroic mirrors 115, 115, 115, a coupling optical system 116, and a BD signal detection circuit 118. The coupling optical system 116 and the collimating lens 122 are optically connected to each other by an optical fiber 117.

  As shown in FIG. 1, the video signal supply circuit 104 is connected to a blue laser driver 108, a green laser driver 109, and a red laser driver 110, which together form a light source drive circuit 105. The video signal supply circuit 104 supplies a drive signal of each color to the drivers 108, 110, and 112 based on the input video signal.

  As shown in FIG. 1, the video signal supply circuit 104 is also connected to a horizontal scan drive circuit 121 of the horizontal scan system 103 and a vertical scan drive circuit 124 of the vertical scan system 102, and is necessary for synchronizing the scanning operation. The horizontal synchronization signal 119 and the vertical synchronization signal 120 are supplied to the corresponding driving circuits 121 and 124, respectively.

  As shown in FIG. 1, the video signal supply circuit 104 is connected to a BD signal detection circuit 118, and the BD signal detection circuit 118 is connected to a beam detector 123 that detects the scanning light of the optical scanning device 1. .

  When the scanning light enters the beam detector 123, a BD signal indicating the fact is output from the beam detector 123. The output BD signal is input to the BD signal detection circuit 118. The video signal supply circuit 104 forms a frame for each of a plurality of lines forming one frame of an image to be formed by using the BD signal input from the BD signal detection circuit 118. For this purpose, the timing for outputting the driving signals of the respective colors to the respective drivers 108, 109 and 110 is determined.

  The blue laser driver 108, the green laser driver 109, and the red laser driver 110 each transmit a drive signal for modulating the intensity of the laser light of each color based on the drive signal of each color supplied from the video signal supply circuit 104. To the green laser 112 and the red laser 113, thereby driving each of the lasers 111, 112, and 113. The blue laser 111, the green laser 112, and the red laser 113 are laser beams corresponding to blue, green, and red wavelengths, respectively, based on drive signals from the blue laser driver 108, the green laser driver 109, and the red laser driver 110, respectively. Then, the laser beam whose intensity is modulated is generated as a laser beam (laser beam).

  As shown in FIG. 1, the collimating optical system 107 includes collimating lenses 114, 114, and 114. The collimating lenses 114, 114, and 114 convert the three color laser beams diffusely radiated from the blue laser 111, the green laser 112, and the red laser 113 into parallel light, and enter the dichroic mirrors 115, 115, and 115, respectively. Let it. The dichroic mirrors 115, 115, 115 combine laser light of three colors, and the combined laser light enters the coupling optical system 116.

  The laser light that has entered the coupling optical system 116 enters the collimator lens 122 via the optical fiber 117. Laser light diffusely emitted from the end of the optical fiber 117 is converted into parallel light by the collimating lens 122. The collimated laser light is incident on the reflection mirror 8 of the optical scanning device 1 provided as a horizontal scanning device in the horizontal scanning system 103.

  The optical scanning device 1 is used to change the reflection direction of the laser light incident on the reflection mirror 8 and scan the laser light in the horizontal direction. In the optical scanning device 1, for the horizontal scanning, the horizontal scanning drive circuit 121 is controlled based on the horizontal synchronization signal 119 supplied from the video signal supply circuit 104, and the reflection mirror 8 is vibrated by the horizontal scanning drive circuit 121. Let me do. The laser light scanned by the optical scanning device 1 due to the vibration is guided to the reflection mirror unit 125 of the vertical scanning system 102 via the relay optical system 126.

  The vertical scanning system 102 includes a vertical scanning drive circuit 124 that is controlled based on a vertical synchronization signal 120 supplied from the video signal supply circuit 104. The vertical scanning drive circuit 124 drives an actuator (not shown) to swing (rotate) the reflection mirror unit 125 in the direction indicated by the arrow in FIG. Thereby, the reflection direction of the laser light incident on the reflection mirror unit 125 is changed, and the reflected laser light is scanned in the vertical direction.

  That is, in the present embodiment, the laser light is two-dimensionally scanned by the cooperative action of the optical scanning device 1 of the horizontal scanning system 103 and the reflection mirror unit 125 of the vertical scanning system 102. The laser light scanned in this manner is shaped by the relay optical system 127, enters the pupil of the observer, and is projected as an image directly on the retina.

  FIG. 2 is a block diagram showing details of the horizontal scanning drive circuit 121 of the horizontal scanning system 103. The horizontal scanning drive circuit 121 includes an oscillator 121a, a phase inversion circuit 121b, phase shifters 121c and 121d, and amplifiers 121e and 121f.

  The horizontal synchronizing signal 119 is supplied to the oscillator 121a from the video signal supply circuit 104 shown in FIG. The oscillator 121a generates a sine wave signal based on the horizontal synchronization signal 119, and the generated sine wave is input to the phase inversion circuit 121b and the phase shifter 121c.

  The phase shifter 121c to which the horizontal synchronization signal 119 has been input generates a signal for adjusting the phase between the image signal of the video signal supply circuit 104 and the reflection mirror unit 125 of the optical scanning device 1. When the generated signal is amplified by the amplifier 121e, a driving voltage is supplied to the driving sources a and b provided in the optical scanning device 1, respectively.

  On the other hand, the phase inversion circuit 121b, to which the same horizontal synchronization signal 119 is input from the oscillator 121a, supplies an inverted signal obtained by inverting the phase of the input horizontal synchronization signal 119 to the amplifier 121f via the phase shifter 121d. The phase shifter 121d and the amplifier 121f operate in the same manner as described above. As a result, the drive voltage reflecting the inverted signal is supplied to the drive sources c and d provided in the optical scanning device 1, respectively.

  In the present embodiment, the first set of drive sources a and b and the second set of drive sources c and d are driven in opposite phases to each other, so that each of the drive sources a, b, c, The displacement directions at each moment of d are opposite to each other between the two sets. In the present embodiment, as will be described later, the first set and the second set are arranged in the optical scanning device 1 so as to face each other across the swing center line of the reflection mirror 8. Therefore, when the two sets are driven in opposite phases to each other, the reflecting mirror 8 is swung by torsional vibration, and as a result, the laser light reflected from the reflecting mirror 8 is scanned in the horizontal direction.

  The laser light scanned in this manner is guided to the reflection mirror unit 125 of the vertical light scanning system 102 via the relay optical system 126 as described above.

  Here, the optical scanning device 1 used in the image forming apparatus 100 will be described in detail with reference to FIGS. FIG. 3 is a perspective view of the optical scanning device 1 in an assembled state, FIG. 4 is an exploded perspective view of the optical scanning device 1, and FIG. 5 is a state of the surface of the reflection mirror 8 of the optical scanning device 1. It is a perspective view for explaining.

  As shown in FIGS. 3 and 4, the optical scanning device 1 includes a substantially rectangular parallelepiped base 2, and a recess 2 a is formed in the base 2 so as to open at the center of the upper surface of the base 2. ing. The vibrating body 5 is fixed to the upper surface of the base 2.

  The vibrating body 5 includes a fixed frame 7, and the fixed frame 7 is supported on the upper surface of the base 2. Specifically, the fixed frame 7 is supported by the support 3 formed around the recess 2 a in the base 2. The upper surface of the support portion 3 is formed as a plane extending with substantially the same width as the fixed frame portion 7 of the vibrating body 5, and the center of the upper surface is hollow. As a result, a rectangular hollow frame similar to the fixed frame portion 7 is formed in the support portion 3.

  Since the concave portion 2a opened on the upper surface of the base table 2 is formed in the base table 2, the reflecting mirror 8 interferes with the base table 2 when the reflecting mirror 8 formed on the vibrating body 5 swings (during vibration). You don't have to. The base 2 is formed to have a fine size, and the recess 2a is formed by, for example, etching.

  Here, the vibrator 5 will be described in detail with reference to FIGS.

  The vibrating body 5 is formed using a thin and small silicon plate having a substantially rectangular shape in a plan view as a base material. A method for manufacturing the vibrating body 5 will be described later in detail.

  A plurality of components of the vibrator 5 are formed on the silicon plate. These components include a reflection mirror 8, first spring portions 9, 10 connected to the reflection mirror 8, second spring portions 12, 13 connected to the first spring portion 9, and There are second spring portions 15, 16 connected to one spring portion 10, and fixed frame portion 7, to which second spring portions 12, 13, 15, 16 are connected.

  These components are formed on a silicon plate by etching. In the present embodiment, the vibrating body 5 is configured by integrally forming these components.

  As shown in FIGS. 3 and 4, the reflection mirror 8 has a rectangular or square shape and is disposed substantially at the center of the vibrating body 5. The reflection mirror 8 is caused to swing around a swing axis extending in the horizontal direction in FIGS. 3 and 4, thereby changing the reflection direction of light incident on the reflection mirror 8.

  In the vibrating body 5, on one side of the reflection mirror 8, two first spring portions 9 and two second spring portions 12 and 13 are branched from the first spring portion 9 in parallel with each other. A first connecting member is formed by connecting the second spring portions 12 and 13 to each other. Similarly, on the other side of the reflection mirror 8, the first spring portion 10 and the two second spring portions 15 and 16 are branched from the first spring portion 10 in parallel with each other. The 2nd connection body which the 2nd spring parts 15 and 16 are mutually connected is arranged. The first and second connectors are arranged so as to have a relative positional relationship symmetric with respect to the reflection mirror 8.

  In the first coupling body, the two second spring portions 12 and 13 are both located on one side of the reflection mirror 8 and face each other across the oscillation axis, and similarly, in the second coupling body. The two second spring portions 15 and 16 are both located on the other side of the reflection mirror 8 and face each other across the swing axis. The drive sources a and b are respectively fixed to the two second spring portions 12 and 13 belonging to the first connection body, while the drive sources a and b are attached to the two second spring portions 15 and 16 belonging to the second connection body. c and d are respectively fixed.

  As shown in FIG. 5, a light reflection film 8a is formed on the surface of the reflection mirror 8, and high reflection efficiency is realized. It is desirable to set the vibration frequency at the time of operating the reflection mirror 8 for optical scanning, that is, the operating vibration frequency to be substantially equal to the resonance frequency of the reflection mirror 8 in order to stabilize the vibration state of the reflection mirror 8. .

  As shown in FIGS. 3 and 4, the first spring portions 9 and 10 and the second spring portions 12, 13, 15 and 16 twist the reflection mirror 8 arranged substantially at the center of the fixed frame portion 7. It is supported so that it can vibrate.

  Specifically, as is apparent from the above description, each of the first spring portions 9 and 10 is connected at one end to the center in the width direction of both side edges of the reflection mirror 8, and torsional vibrations around the oscillation axis. (Repeated torsion deformation).

  The second spring portions 12, 13, 15, 16 are subjected to torsional vibration (repetition of torsional deformation) around each center line (longitudinal axis), and at the same time, bending vibration (bending) in a plane perpendicular to each plate surface. Geometric features, such as shape and orientation, are set in advance so that the deformation is repeated.

  The two second spring portions 12 and 13 are both connected to the other end of the first spring portion 9, and are separated from the first spring portion 9 at an interval wider than the width of the first spring portion 9. Forked. As apparent from FIGS. 3 and 4, the two second spring portions 12 and 13 are separated by a gap which is wider than the width of the first spring portion 9 and extends along the swing axis. They are facing each other. The two second spring portions 12 and 13 are both connected to the other end of the first spring portion 9 at one end thereof, and are connected to the fixed frame portion 7 at the other end thereof. ing.

  Similarly, the two second spring portions 15 and 16 are both connected to the other end of the first spring portion 10, and the first spring portions 10 are spaced apart from the first spring portion 10 by an interval wider than the width of the first spring portion 10. It is branched from the spring portion 10. As apparent from FIGS. 3 and 4, the two second spring portions 15 and 16 are separated by a gap wider than the width of the first spring portion 10 and extending along the swing axis. They are facing each other. The two second spring portions 15 and 16 are both connected to the other end of the first spring portion 10 at one end thereof, and are connected to the fixed frame portion 7 at the other end thereof. ing.

  In short, in the present embodiment, the first spring portions 9 and 10 directly support the reflection mirror 8 on both sides thereof, while the second spring portions 12 and 13 are connected via the first spring portion 9. The second spring portions 15 and 16 support the reflection mirror 8 indirectly via the first spring portion 10.

  As described above, the two second spring portions 12 and 13 are branched from the first spring portion 9 at intervals larger than the width of the first spring portion 9, and similarly, the two second spring portions 12 and 13 are separated from each other. The two spring portions 15 and 16 are branched from the first spring portion 10 at intervals larger than the width of the first spring portion 10.

  Here, the width dimension of each of the first spring portions 9 and 10 is W, and the branch interval between each of the first set of second spring portions 12 and 13 and the second set of second spring portions 15 and 16 is It is denoted by D, respectively. Further, the branch distance D means the distance between the outer edges of the first set of second spring portions 12, 13 and the second set of second spring portions 15, 16 similarly to L2 in FIG. Is defined as According to this definition, the branch interval D is about 10 times the width W (in the case of the vibrating body 5 shown in FIG. 24), a value within a range of about 9 to 11 times, or about 8 to 12 times. It is desirable to use a value within the range, or a value within the range of about 2 to 15 times.

  As shown in FIGS. 3 and 4, the second spring portions 12 and 13 are formed so as to form an L-shape or an inverted L-shape in plan view. The other end is connected to the fixed frame 7 substantially vertically. Similarly, the second spring portions 15 and 16 are formed so as to form an L-shape or an inverted L-shape in plan view, and one ends of the second spring portions 15 and 16 are connected to the first spring portion 10 substantially vertically, On the other hand, each other end is connected to the fixed frame 7 substantially vertically.

  In the present embodiment, as described above, two second spring portions 12 and 13 are integrally connected to one first spring portion 9, and similarly, one first spring portion Two second spring portions 15 and 16 are integrally connected to 10. The first spring portions 9 and 10 are arranged on a straight line (the above-mentioned swing axis) passing through the center of gravity of the reflection mirror 8, and the second spring portions 12 and 13 are symmetrical about the straight line. Are located in The second spring portions 15, 16 are also arranged symmetrically about the straight line.

  Therefore, according to the present embodiment, the first spring portions 9, 10 and the second spring portions 12, 13, 15, 16 are configured as described above, so that the reflection mirror 8 is used for optical scanning. In the case of torsional vibration, the stress generated in the vibrating body 5 is dispersed throughout the vibrating body 5 to reduce, for example, the stress generated in the connection point between the second spring portions 12, 13, 15, 16 and the fixed frame portion 7. It is easy to relax.

  Therefore, according to the present embodiment, in order for the spring portions 9, 10, 12, 13, 15, 16 to withstand the stress generated thereby, the spring portions 9, 10, 12, 13, 15, 16 are unnecessarily thickened. Even if the length is not increased, it is easy to obtain a sufficiently large torsion angle, that is, the scanning angle, while securing the resonance frequency, that is, the scanning frequency, of the reflection mirror 8.

  As a result, according to the present embodiment, it is easy to achieve both an increase in the scanning frequency and an increase in the scanning angle while reducing the size of the optical scanning device 1 and the image forming apparatus 100 in which the optical scanning device 1 is mounted. .

  Furthermore, according to the present embodiment, it is possible to achieve the intended purpose while suppressing an increase in the size of the spring portions 9, 10, 12, 13, 15, 16. , 13, 15 and 16, it is easy to avoid the occurrence of unnecessary vibration modes due to the enlargement of the reflection mirror 8, that is, the occurrence of vibration modes other than the torsional vibration mode on the reflection mirror 8.

  Note that in the present embodiment, in the present embodiment, the above-described first and second coupling bodies in the vibrating body 5 are each configured by one first spring portion and two second spring portions. Each second spring portion is considered to be configured by integrally forming an original second spring portion and a connecting portion for connecting the original second spring portion to the first spring portion. It is possible.

  If the latter viewpoint is adopted, in FIG. 3, for example, of the first and second linear portions orthogonal to each other to form the second spring portion 12, the first and second straight portions are connected at right angles to the first spring portion 9. The first linear portion to be formed constitutes an example of the above-described connecting portion. The first connecting portion is connected to the first spring portion 9 and the second straight portion of the second spring portion 12 at right angles.

  Further, in the present embodiment, each of the driving sources a, b, c, and d is attached to any of the second spring portions 12, 13, 15, and 16 in a posture that does not reach the first linear portion. This prevents torsional vibration and bending vibration of the first linear portion from being hindered by the driving sources a, b, c, and d.

  As shown in FIG. 4, the fixed frame 7 supports the second springs 12, 13, 15, 16 connected to the first springs 9, 10 connected to the reflection mirror 8, And a function of fixing the vibrating body 5 to the base 2. Specifically, the fixed frame 7 is fixed to the support 3 of the base 2 on the lower surface thereof.

  Here, a method for manufacturing the vibrating body 5 will be described in detail.

  In order to manufacture the vibrating body 5 having the above-described structure, for example, a fixed frame portion 7, a reflection mirror 8, first spring portions 9, 10 and second spring portions 12, 13, A pattern of the vibrating body 5 composed of 15 and 16 is formed, and is etched to form them integrally. After that, as shown in FIG. 5, a vibrating body 5 is completed by forming a reflection film 8a on the surface of a portion to be the reflection mirror 8 using a material such as gold, chromium, platinum, or aluminum. According to this manufacturing method, a plurality of vibrators 5 having the same specifications can be manufactured simultaneously.

  Next, a method of forming the driving sources a, b, c, and d will be described in detail with reference to FIGS. 3, 4, 6, and 7. FIG. FIG. 6 is a partial side view of the vibrating body 5 viewed from the width direction. FIG. 7 is a partial view of the vibrating body 5 viewed from the width direction, and shows a detailed structure of a typical driving source d. It is a partial side view.

  As shown in FIGS. 3 and 4, the driving sources a, b, c, and d are formed directly on the second spring portions 12, 13, 15, and 16, respectively.

  The driving sources a, b, c, and d are configured using a piezoelectric material such as PZT, ZnO, or BST. Since the piezoelectric body is an element having high electro-mechanical conversion efficiency, the use of piezoelectric bodies for the driving sources a, b, c, and d facilitates low power consumption. As is well known, when an alternating voltage is applied to a piezoelectric body at a predetermined frequency, the piezoelectric body repeatedly expands and contracts at the same frequency as the voltage frequency, and as a result, vibrates.

  For forming the driving sources a, b, c, and d using a piezoelectric material such as PZT, ZnO, or BST, a thin film forming method such as CVD, sputtering, hydrothermal synthesis, sol-gel, or fine particle spraying is used. The drive sources a, b, c, d are formed directly on the second spring portions 12, 13, 15, 16 respectively.

  In the present embodiment, as shown in FIGS. 3, 4, 6, and 7, the driving sources a, b, c, and d respectively correspond to the upper surfaces of the corresponding second spring portions 12, 13, 15, and 16. It is attached to the vibrating body 5 in a posture that extends (extends) over the upper surface of the fixed frame portion 7. Specifically, as shown in FIG. 6 and FIG. 7, the typical driving source d vibrates in a posture in which the second spring portion 13 and the fixed frame portion 7 pass through the fixed end portion 13 a adjacent to each other. It is attached to the body 5.

  As shown in FIGS. 3 and 4, input terminals a1 and a2 for inputting a driving voltage to the driving source a and input terminals b1 and d1 for inputting the driving voltage to the driving source b are provided on the fixed frame portion 7. , B2, input terminals c1 and c2 for inputting a drive voltage to the drive source c, and input terminals d1 and d2 for inputting a drive voltage to the drive source d are formed of metal thin films, respectively.

  In the present embodiment, even if the material forming the vibrating body 5 has high brittleness, a large deformation is possible if the material is made thin, so that the vibrating body 5 has a thickness of the driving sources a, b, c, and d. And the thickness of the second spring portions 12, 13, 15, 16 are configured so that the total value is 200 μm or less.

  Here, the structure of the driving sources a, b, c, and d will be described in detail with reference to FIG. 7 taking the driving source d as an example.

  As shown in FIG. 7, the drive source d is formed to extend from the second spring portion 13 to the fixed frame portion 7. The drive source d is sandwiched between a pair of electrodes d3 and d4 facing each other in the thickness direction of the drive source d, thereby forming a sandwich structure. In FIG. 7, a lower electrode d4 is arranged below the driving source d, and an upper electrode d3 is arranged above the driving source d.

  As shown in FIGS. 3, 4 and 7, the upper electrode d3 is connected to the input terminal d2, and as shown in FIGS. 3 and 4, the lower electrode d4 is connected to the input terminal d1.

  In addition, in this embodiment, since a pair of electrodes d3 and d4 are integrally mounted on each of the driving sources a, b, c and d, from the viewpoint of material dynamics, a pair of electrodes d3 and d4 are provided. A stacked body in which the driving sources a, b, c, and d are sandwiched by d4 may be recognized as the driving source.

  Next, the relationship between the stiffness of the first spring portions 9 and 10 and the stiffness of the second spring portions 12, 13, 15 and 16 and the elastic deformation portions will be described with reference to the first spring portion 9 and the second spring portion. This will be described with reference to FIGS. 5 and 7, taking a combination with the unit 13 as an example.

  In the present embodiment, the elastically deformable portions of the second spring portions 12, 13, 15, 16 mainly include the second spring portions 12, 13, 15, 16 and the driving source a fixed thereto. , B, c, d. The rigidity means resistance to deformation against external force. Specifically, the rigidity of the first spring portions 9 and 10 means torsional rigidity, and the rigidity of the elastically deformable portion is torsional rigidity and bending. It means both rigidity.

  In the example shown in FIG. 7, first, the second moment of area of the first spring portion 9 (the second moment of area in the AA ′ section shown in FIG. 7) and the second moment of area of the second spring portion 13 (Second moment of area in section BB 'shown in FIG. 7) are compared with each other. The first spring portion 9 and the second spring portion 13 are common to each other with respect to the plate thickness dimension. However, as shown in FIG. 5, regarding the width dimension, the first spring portion 9 is longer than the second spring portion 13.

  On the other hand, as shown in FIG. 10, for a beam member having a rectangular cross section having a plate thickness dimension h and a width dimension b, generally, under the condition that the plate thickness dimension h is constant, the larger the width dimension b, the higher the bending rigidity. The torsional rigidity also increases, and the deformation resistance to external force increases. The bending stiffness of this beam member is represented by the product of the longitudinal elastic modulus E and the second moment of area Iz.

Ebh ^3/12

Is represented by On the other hand, the torsional stiffness is approximately expressed as G when the transverse elastic modulus is represented by G under the condition that the thickness h is considerably smaller than the width b.

Gbh ^3/3

Is represented by In FIG. 10, “dA” means a minute area element at a distance of y from the neutral axis (coincident with the x axis) of the beam member.

  Therefore, in this embodiment, the second moment of area of the second spring portion 13 is smaller than the second moment of area of the first spring portion 9.

On the other hand, such a relationship of the second moment of area is caused by selecting the width of the second spring portion 13 to be smaller than the width of the first spring portion 9 in the present embodiment. Further, as described above, in the beam member having the rectangular cross section, the term “bh ³ ” exists in both the calculation formula of the bending stiffness and the calculation formula of the torsional stiffness, which means that the width dimension of the beam member is short. This means that the bending rigidity and the torsional rigidity of the beam member decrease.

  Therefore, in the present embodiment, the second spring portion 13 is more likely to be elastically torsionally deformed than the first spring portion 9. Although the first spring portion 9 is not basically bent and deformed, in the present embodiment, the second spring portion 13 is more elastic than the first spring portion 9 regardless of the type of deformation. It can be said that it is easily deformed.

  Further, in the present embodiment, the second moment of area of the laminated body of the second spring portion 13 and the driving source d, that is, the elastically deformable portion is smaller than the second moment of area of the first spring portion 9. The cross-sectional shapes of the second spring portion 13 and the drive source d and the elastic modulus of the drive source d are selected in advance.

  As a result, in the present embodiment, the bending deformation and the torsional deformation of each elastically deforming portion (a laminate of one second spring portion and the corresponding driving source) are caused by the torsion of the first spring portion 9. This is more likely to occur than deformation.

  On the other hand, in the present embodiment, the swing angle, that is, the scan angle of the reflection mirror 8 is a combination of the torsion deformation amount of the first spring 9 and the torsion deformation amount and the bending deformation amount of the elastic deformation portion. .

  Therefore, according to the present embodiment, the elastically deformable portion that is easily deformed is used in combination with the first spring portion 9, so that the scanning of the reflection mirror 8 can be performed in comparison with the case where there is no elastically deformable portion. It is easy to increase the angle.

  Further, according to the present embodiment, the first spring portion 9 is connected to the fixed frame portion 7 via the elastically deformable portion which is more easily deformed, so that the first spring portion 9 is swung when the reflection mirror 8 swings. 9 can be easily reduced.

  Next, the operation of the optical scanning device 1 configured as described above will be described with reference to FIG. 1, FIG. 2, FIG. 3, and FIG. FIG. 8 is a perspective view showing the vibrating body 5 in a resonance state.

  A horizontal synchronization signal 119 is supplied from the video signal supply circuit 104 shown in FIG. 1 to the optical scanning device 1, and the supplied horizontal synchronization signal 119 is input to the oscillator 121a of the horizontal scanning drive circuit 121 shown in FIG. The oscillator 121a generates a sine wave based on the horizontal synchronization signal 119. The generated sine wave is input to the phase inversion circuit 121b and the phase shifter 121c.

  When the sine wave is input to the phase shifter 121c, the phase shifter 121c generates a signal for adjusting the phase of the image signal and the phase of the reflection mirror 8, and based on the generated signal, the amplifier 121e and the amplifier 121e. , The driving voltage is supplied to the driving source a formed on the second spring portion 12 via the input terminals a1 and a2. Further, a drive voltage having the same phase as the drive voltage is supplied to the drive source b formed in the second spring portion 15 via the input terminals b1 and b2.

  On the other hand, when the sine wave is input to the phase inversion circuit 121b, the phase of the input sine wave is inverted in the phase determination circuit 121b, and the sine wave generated in this manner is shifted by the phase shifter. 121d. In the phase shifter 121d, a signal for adjusting the phase between the image signal and the reflection mirror 8 is generated, and based on the generated signal, the driving voltage is changed to the input terminals d1 and d2 by the joint action with the amplifier 121f. Is supplied to the drive source d formed in the second spring portion 13 via Further, a drive voltage having the same phase as the drive voltage is supplied to the drive source c formed in the second spring portion 16 via the input terminals c1 and c2.

  Therefore, when each of the driving sources a and b attached to one surface of each of the second spring portions 12 and 15 expands, the second spring portions 12 and 15 bend downward in FIG. At the same time, when each of the driving sources c and d attached to one surface of each of the second spring portions 13 and 16 expands, the second spring portions 13 and 16 bend upward in FIG.

  Further, when the drive sources a and b are bent upward, the second spring portions 12 and 15 are also bent upward, and at the same time, when the drive sources c and d are bent downward, the second spring portions 13 and 16 are also directed downward. To bend.

  As described above, in the present embodiment, the horizontal scanning drive circuit 121 controls the drive sources a and b and the drive sources c and d based on the horizontal synchronization signal 119 supplied from the video signal supply circuit 104 shown in FIG. The applied drive voltage is oscillated at the same frequency as the resonance frequency of the reflection mirror 8 and in opposite phases.

  As a result, the second spring portions 12, 15 and 13, 16 of the vibrating body 5 bend so as to be bent in opposite directions, and the vibrating body 5 resonates at the resonance frequency. Due to this resonance, the reflection mirror 8 supported by the first spring portions 9 and 10 moves between the neutral position (stationary position) S shown in FIG. 8 and the maximum swing position (maximum displacement position) K at the time of resonance. The oscillation is repeated, and as a result, the laser light incident on and reflected by the reflection mirror 8 is scanned in the horizontal direction.

  As shown in FIG. 1, the laser light horizontally scanned by the reflection mirror 8 is guided to the reflection mirror unit 125 of the vertical scanning system 102 via the relay optical system 126. The laser light incident on the reflection mirror section 125 is scanned in the vertical direction by the vertical scanning system 102. The laser beam that has been vertically scanned is shaped into a beam by the relay optical system 127, is incident on the pupil of the observer, and soon an image is directly projected on the retina.

  As described above, in the present embodiment, the second moment of area of the second spring portion 12 on which the drive source a is formed and the second moment of area of the second spring portion 13 on which the drive source d is formed are respectively The vibrating body 5 is configured to be smaller than the second moment of area of the first spring portion 9. Further, the second moment of area of the second spring portion 15 on which the drive source b is formed and the second spring portion 16 of the second spring portion 16 on which the drive source c is formed is larger than the second moment of area of the first spring portion 10. The vibrating body 5 is formed to be small.

  Therefore, according to the present embodiment, the driving sources a, b, c, and d and the second spring portions 12, 13, 15, 16 are relatively easily deformed, and the deformation is finally changed by the reflection mirror 8 Is reflected in the torsion, that is, the swing of the reflection mirror 8, so that it is easy to increase the scanning angle (deflection angle) of the reflection mirror 8.

  Further, in the present embodiment, the driving sources a, b, c, d are formed directly on the second spring portions 12, 13, 15, 16 by a thin film forming method. Therefore, according to the present embodiment, an adhesive layer made of a synthetic resin or the like is not interposed between each of the driving sources a, b, c, and d and each of the second spring portions 12, 13, 15, and 16. Only Therefore, according to the present embodiment, the connection state between each of the driving sources a, b, c, and d and each of the second spring portions 12, 13, 15, 16 is stabilized, and the vibration of the vibrating body 5 is also stabilized.

  Further, in the present embodiment, since a mechanism for expanding the vibration of the driving sources a, b, c, and d is employed in the vibrating body 5, the reflecting mirror 8 is vibrated at a predetermined scanning frequency and a predetermined scanning angle. This makes it easier to reduce the power consumption required for

  Further, in the present embodiment, each of the driving sources a, b, c, and d is directly mounted on each of the second spring portions 12, 13, 15, and 16, so that the elastically deforming portion and the vibration source are mutually connected. Positionally matched. Therefore, according to the present embodiment, it is easy to efficiently transmit the vibrations of the respective driving sources a, b, c, and d to the vibrating body 5, so that the power consumption can be easily saved and the optical scanning device 1 Downsizing becomes easy.

  Further, in the present embodiment, as shown in FIG. 6, each of the driving sources a, b, c, and d vibrates in a posture extending from each of the second spring portions 12, 13, 15, 16 to the fixed frame portion 7. It is formed on the body 5. Therefore, according to the present embodiment, the node of the vibration of the vibrating body 5 is stably located at the fixed end portion 13a, and the vibration state of the vibrating body 5 is stabilized in an ideal resonance state.

  Therefore, according to the present embodiment, as shown in FIG. 9, each of the driving sources a, b, c, and d is formed only on each of the second spring portions 12, 13, 15, and 16, and the fixed frame portion is formed. 7, it becomes easier to stabilize the vibrating state of the vibrating body 5 as compared with the case where the vibrating body 5 is formed so as not to exceed 7.

  Next, a second embodiment of the present invention will be described. However, since this embodiment has many elements common to the first embodiment, the common elements will be referred to using the same reference numerals or names, and detailed description will be omitted. Only different elements will be described. , Will be described in detail.

  As shown in FIG. 11, an optical scanning device 200 according to the present embodiment includes a base 2 and a vibrator 5 as components having the same configuration as the optical scanning device 1 according to the first embodiment. In the same manner as in the first embodiment, as shown in FIG. In the present embodiment, as shown in FIG. 11, as in the first embodiment, the vibrating body 5 includes a fixed frame 7, a reflection mirror 8, first springs 9 and 10, and a second spring. Spring portions 12, 13, 15, 16 are provided.

  In the first embodiment, as shown in FIG. 3, the vibrations of the driving sources a, b, c, and d are transmitted directly to the vibrating body 5. That is, the vibrating body 5 is directly vibrated by the driving sources a, b, c, and d.

  On the other hand, in the optical scanning device 200 according to the present embodiment, as shown in FIG. 11, the vibrating body 5 is indirectly vibrated by the driving sources e and f. That is, the entire optical scanning device 200 is vibrated.

  As shown in FIG. 11, in this embodiment, drive sources e and f are fixed to the lower surface of the base 2 by bonding. These two drive sources e and f are respectively arranged at two opposing positions opposing each other in the width direction of the base table 2 (direction perpendicular to the longitudinal direction of the base table 2).

  The drive sources e and f are both configured as a laminated piezoelectric actuator. The laminated piezoelectric actuator is configured by laminating a plurality of piezoelectric bodies, such as PZT, ZnO, and BST, extending in the longitudinal direction of the base 2 in a direction perpendicular to each plate surface. Since the piezoelectric body is an element having high electro-mechanical conversion efficiency, the use of the piezoelectric bodies for the driving sources e and f facilitates low power consumption.

  As shown in FIG. 12, the drive source e is sandwiched between an upper electrode e1 and a lower electrode e2. Similarly, the driving source f is sandwiched between the upper electrode f1 and the lower electrode f2.

  The drive source e expands and contracts and vibrates by changing the polarity of the drive voltage applied between the electrode e1 and the electrode e2 at a predetermined frequency. Similarly, the drive source f expands and contracts and vibrates by changing the polarity of the drive voltage applied between the electrode f1 and the electrode f2 at a predetermined frequency. Therefore, if drive voltages are applied to the drive source e and the drive source f in opposite phases, the drive source e and the drive source f vibrate in opposite phases, thereby causing the vibrating body 5 to move through the base 2. Vibration can be performed in the same manner as in the first embodiment.

  As shown in FIG. 11, the base 2 has a recess formed in the upper surface of the base 2 so as to be basically common to the first embodiment. It is formed in a step shape. Specifically, a concave portion 2b having a deep bottom surface is formed at a longitudinal center portion of the base table 2, and a concave portion 2c having a shallow bottom surface is formed at two positions sandwiching the concave portion 2b.

  FIG. 13 is a block diagram showing the horizontal scanning drive circuit 121 according to the present embodiment. The horizontal scanning drive circuit 121 has the same basic electric circuit as the first embodiment. The difference from the first embodiment is that the amplifier 121e is connected to one drive source e, 121f is connected to one drive source f.

  According to the horizontal scanning drive circuit 121 configured as described above, drive voltages are applied to the drive sources e and f, respectively, in opposite phases, so that the drive sources e and f vibrate in opposite phases. Can be As a result, the vibrating body 5 constituted by the first spring portions 9 and 10, the second spring portions 12, 13, 15, 16 and the reflecting mirror 8 is provided with a Vibration is applied. Thereby, the vibrating body 5 resonates, and the reflection mirror 8 induces torsional vibration under the resonance frequency and the large swing angle.

  With respect to the vibrating body 5 common to the first and second embodiments described above, the present inventors use a computer to analyze the relationship between the shape and dimension, which are geometrical features of the vibrating body 5, and vibration characteristics. Numerical analysis was performed by simulation. The numerical analysis is based on the finite element method.

  FIG. 14 schematically shows an analysis model of the vibrating body 5 used for the numerical analysis. The analysis model is configured by dividing the vibration body 5 into a plurality of finite elements.

  As shown in FIG. 14, in this analysis model, the width dimension of the reflection mirror 8 is represented by “L1”, while a pair of second spring portions 12 and 13 and another pair of second spring portions are provided. For each of Nos. 15 and 16, the branch interval is represented by “L2”. Here, the "branch interval L2" means the interval between the outer edges of the pair of second spring portions 12, 13 by taking the pair of second spring portions 12, 13 as an example. The branch interval L2 is equal to the length of each of the connecting portions 17 and 18.

  In addition, in the analysis model shown in FIG. 14, a portion of the two second spring portions 12 and 13 that is connected to the first spring portion 9 is the two second spring portions 12 and 13. 13 is referred to as a connecting portion 17 independently from the name. Similarly, a portion of the two second spring portions 15 and 16 that is connected to the first spring portion 10 is connected to the connection portion independently of the two second spring portions 15 and 16 in name. No. 18.

  The first numerical analysis, the second numerical analysis, and the third numerical analysis were performed using the above-described analysis model to analyze the vibration characteristics of the vibrating body 5. Three types of numerical analysis were performed, and the analysis conditions common to the three types of numerical analysis are as follows.

1. Dimensions of reflection mirror 8 (square) Thickness: 100 μm
Length: 1mm
Width: 1mm

2. Dimensions of first spring portions 9 and 10 (rectangle) Thickness: 100 μm
Length: 0.5mm
Width: 60 μm

3. Dimensions of second spring portions 12, 13, 15, 16 (rectangle) Thickness: 100 μm
Length: 1.5mm
Width: 40 μm

4. Dimensions of connecting parts 17 and 18 (rectangle) Thickness: 100 μm
Width: 40 μm

  Therefore, through these three types of numerical analysis, the width L1 of the reflection mirror 8 was maintained at 1 mm.

  On the other hand, these three types of numerical analysis were performed under three types of branch intervals L2. Specifically, the first numerical analysis was performed under the condition that the lengths of the connecting portions 17 and 18 were 0.6 mm and the branch interval L2 was 0.6 mm. This numerical analysis is ultimately performed under the branch interval L2 that does not exceed the width L1 of the reflection mirror 8. Specifically, this numerical analysis indicates that the branch interval L2 is smaller than the width L1 of the reflection mirror 8 (for example, within the range of 50 to 70%, within the range of 40 to 80%, or within the range of 30 to 90%). It was done under.

  On the other hand, the second and third numerical analyzes were both performed under the condition that the branch interval L2 exceeds the width L1. Specifically, the second numerical analysis is performed under the condition that the branch interval L2 is 1.1 mm, while the third numerical analysis is performed under the condition that the branch interval L3 is 2 mm. It was implemented.

  FIG. 15 shows the analysis model (hereinafter, simply referred to as “vibrator 5”) of the vibrator 5 shown in FIG. 14 in a stationary state. The first numerical analysis was performed to simulate the vibrating body 5 in four different vibration modes. The four types of vibration modes are different as follows with respect to the vibration frequency at which the vibrating body 5 vibrates.

Vibration mode 1: 10.6kHz
Vibration mode 2: 15.1 kHz
Vibration mode 3: 21.8 kHz
Vibration mode 4: 25.2 kHz

  Hereinafter, the results of the first numerical analysis will be described with reference to FIGS.

  Prior to that, the contents of FIGS. 16 to 23 will be briefly described.

  16 to 19 are diagrams each independently showing the analysis result of each vibration mode. Specifically, FIG. 16 is a diagram showing an analysis result of vibration mode 1, FIG. 17 is a diagram showing an analysis result of vibration mode 2, and FIG. 18 is a diagram showing an analysis result of vibration mode 3. FIG. 19 is a diagram showing an analysis result of the vibration mode 4.

  FIGS. 20 to 23 show the analysis results of the respective vibration modes, which are shown in FIGS. 16 to 19, respectively, for convenience of comparison with the vibrating body 5 in the stationary state shown in FIG. FIG. Specifically, FIG. 20 is a diagram showing the analysis result of the vibration mode 1 in comparison with the vibration body 5 in the stationary state, and FIG. 21 is a diagram showing the analysis result of the vibration mode 2 in the vibration state 5 in the stationary state. FIG. 22 is a diagram showing the analysis result of the vibration mode 3 in comparison with the vibration body 5 in the stationary state, and FIG. 23 is a diagram showing the analysis result of the vibration mode 4 in the stationary state. FIG. 9 is a diagram shown in comparison with a certain vibrating body 5.

  As shown in FIGS. 16 and 20, when the vibrating body 5 is vibrated at the vibration mode 1, that is, at 10.6 kHz, the reflecting mirror 8 vibrates in a direction parallel to the reflecting surface 8a (in-plane vibration). And resonate.

  Further, as shown in FIGS. 17 and 21, when the vibrating body 5 is vibrated at the vibration mode 2, that is, at 15.1 kHz, the reflection mirror 8 vibrates in a direction perpendicular to the reflection surface 8a (out-of-plane vibration). ) To resonate.

  Also, as shown in FIGS. 18 and 21, when the vibrating body 5 is vibrated at the vibration mode 3, that is, at 21.8 kHz, the reflection mirror 8 rotates around the axis of the first spring portions 8 and 9. It moves to a state of torsional resonance.

  As shown in FIGS. 19 and 23, when the vibrating body 5 is vibrated at the vibration mode 4, that is, at 25.2 kHz, the reflecting mirror 8 is rotated about the center point of the reflecting surface 8a. 8 reciprocates along the reflection surface 8a and resonates.

  According to the first numerical analysis result, the vibration mode 3 among the vibration modes 1 to 4 is a vibration mode that can be suitably used for light scanning.

  FIG. 24 illustrates analysis conditions under which the second numerical analysis is performed. In the second numerical analysis, the length of the connecting portions 17 and 18 of the vibrating body 5 is set to 1.1 mm, which is longer than that in the first numerical analysis. Accordingly, the branch interval L2 is also 1.1 mm, which is slightly longer than the width L1 of the reflecting mirror 8 of 1 mm.

  FIG. 25 shows the vibrating body 5 shown in FIG. 24 in a stationary state. The second numerical analysis was performed to simulate the vibrating body 5 in four different vibration modes. The four types of vibration modes are different as follows with respect to the vibration frequency at which the vibrating body 5 vibrates.

Vibration mode 1: 10.0kHz
Vibration mode 2: 14.2 kHz
Vibration mode 3: 22.0 kHz
Vibration mode 4: 25.5 kHz

  Hereinafter, the results of the second numerical analysis will be described with reference to FIGS.

  Prior to that, the contents of FIGS. 26 to 33 will be briefly described.

  26 to 29 are diagrams each independently showing the analysis result of each vibration mode. Specifically, FIG. 26 is a diagram showing an analysis result of vibration mode 1, FIG. 27 is a diagram showing an analysis result of vibration mode 2, and FIG. 28 is a diagram showing an analysis result of vibration mode 3. FIG. 29 is a diagram illustrating an analysis result of the vibration mode 4.

  FIGS. 30 to 33 show the analysis results of the respective vibration modes, which are shown in FIGS. 26 to 29, respectively, for the sake of convenience in comparing with the vibrating body 5 in the stationary state shown in FIG. FIG. More specifically, FIG. 30 is a diagram showing the analysis result of vibration mode 1 in comparison with vibration body 5 in a stationary state, and FIG. 31 is a diagram showing the analysis result of vibration mode 2 in vibration state 5 of a stationary state. FIG. 32 is a diagram showing the analysis result of the vibration mode 3 in comparison with the vibration body 5 in a stationary state, and FIG. 33 is a diagram showing the analysis result of the vibration mode 4 in a stationary state. FIG. 9 is a diagram shown in comparison with a certain vibrating body 5.

  As shown in FIGS. 26 and 30, when the vibrating body 5 is vibrated at the vibration mode 1, that is, at 10.0 kHz, the reflection mirror 8 vibrates in a direction parallel to the reflection surface 8a (in-plane vibration). And resonate.

  Further, as shown in FIGS. 27 and 31, when the vibrating body 5 is vibrated at the vibration mode 2, that is, at 14.2 kHz, the reflection mirror 8 vibrates in a direction perpendicular to the reflection surface 8a (out-of-plane vibration). ) To resonate.

  Further, as shown in FIGS. 28 and 32, when the vibrating body 5 is vibrated at the vibration mode 3, that is, at 22.0 kHz, the reflecting mirror 8 is turned around the center point of the reflecting surface 8a as the center of rotation. 8 reciprocates along the reflection surface 8a and resonates.

  As shown in FIGS. 29 and 33, when the vibrating body 5 is vibrated at the vibration mode 4, that is, at 25.5 kHz, the reflection mirror 8 rotates around the axis of the first spring portions 8 and 9. It moves to a state of torsional resonance.

  According to the second numerical analysis result, the vibration mode 4 among the vibration modes 1 to 4 is a vibration mode that can be suitably used for light scanning.

  Next, primary to tertiary vibration modes of the vibrating body 5 will be described by using an approximate model of the vibrating body 5 with reference to FIG.

  In the upper part of FIG. 34, an approximate model of the vibrating body 5 is shown. In this approximate model, the mass of the reflection mirror 8 is “M1”, the first spring portion is “massless”, the masses of the connecting portions 17 and 18 are “M2”, respectively, and the second spring portion is “massless”. And two second spring portions are combined for convenience to form one second spring portion.

  When the vibrating body 5 is approximated to this approximation model, the vibrating body 5 corresponds to a vibration system having three degrees of freedom in the horizontal direction or the vertical direction, if the mass of the spring portion is ignored.

  In order to stably perform optical scanning, it is desirable that a higher-order (secondary or higher) vibration mode of the vibrator 5 is not generated in a frequency region lower than the natural frequency of torsional vibration. In FIG. 34, the approximate model is shown in a stationary state in the upper part, and three kinds of vibration modes are shown using the approximate model in the lower part. Of these three types of vibration modes, the upper one is the primary mode, the middle one is the secondary mode, and the lower one is the tertiary mode.

  As is clear from the numerical analysis results described with reference to FIGS. 16 to 33, when the mode analysis of the natural frequency of the vibrating body 5 is performed, the vertical translational vibration mode (out-of-plane vibration mode) or the horizontal translational vibration mode ( The primary natural vibration (in-plane vibration mode) occurs in a low frequency region.

  When each of the four types of vibration modes generated in the vibrating body 5 shown in FIG. 14 is associated with one of the three types of vibration modes shown in FIG. 34, the vibration mode 1 (horizontal translation vibration mode) shown in FIG. And the vibration mode 4 (rotational vibration mode) shown in FIG. 19 corresponds to the secondary mode shown in FIG.

  If another numerical analysis is performed at a frequency higher than the frequency at which the current numerical analysis was performed, the vibrating body 5 can be analyzed up to the third-order mode or a higher-order mode.

  In the approximation model shown in FIG. 34, assuming that the mass of M1 and the rigidity of the spring portion are constant, the frequency of the higher-order mode depends on the mass of M2. In the example shown in FIG. 34, the increase in the mass of M2 causes a decrease in the vibration frequency of the primary mode, and also causes a decrease in the vibration frequency of the secondary mode. Therefore, the increase in the mass of M2 has caused the vibration frequency of the higher-order mode to approach the torsional natural frequency required for optical scanning.

  On the other hand, in the vibrating body 5 shown in FIG. 14, that is, in the vibrating body 5 used in the first and second embodiments, the length of the connecting parts 17 and 18, that is, the second spring parts 12 and 13 The mass M2 of the connecting portions 17 and 18 is reduced by making the branch interval L2 of the second spring portions 15 and 16 shorter than the width L1 of the reflecting mirror 8.

  Therefore, in the vibrating member 5 shown in FIG. 14, the primary mode in which the vibration direction is the horizontal direction and the vertical direction with respect to the reflecting mirror 8 despite the fact that the swing speed of the reflecting mirror 8 is increased. The generation of other vibration modes is suppressed, and as a result, the torsional vibration of the vibrating body 5 is stabilized, and the optical scanning is also stabilized. Here, the generation of the primary mode in which the vibration direction is the horizontal direction and the vertical direction with respect to the reflection mirror 8 is permitted. This mode is not a vibration mode necessary for optical scanning, but This is because it is not a vibration mode in which the direction is changed unexpectedly and its straightness is hindered.

  In the first and second embodiments, the vibration mode 3 shown in FIG. 18 is a vibration (resonance) mode suitable for the optical scanning devices 1 and 200, and the natural frequency of this mode is 21.8 kHz. At lower frequencies, the vibration mode 1 shown in FIG. 16 is in a direction (in-plane direction) horizontal to the reflection surface 8a of the reflection mirror 8, and the vibration mode 2 shown in FIG. 17 is perpendicular to the reflection surface 8a. This is a mode in which the direction (out-of-plane direction) is the vibration direction, and only the primary mode in which the vibration direction is vertical and horizontal occurs.

  Therefore, according to the first and second embodiments, the torsional vibration of the vibrating body 5 is stabilized, and the optical scanning by the optical scanning devices 1 and 200 is also stabilized.

  On the other hand, as shown in FIG. 24 as a comparative example, when the length of the connecting portions 17 and 18, that is, the branch interval L2 is 1.1 mm and is longer than the width L1, the necessary vibration mode, that is, FIG. At a frequency of 22.0 kHz, which is lower than the resonance frequency of 25.5 kHz of the torsional vibration mode 4 shown in FIG. 33, as shown in FIGS. 28 and 32, the vibration mode 3 (rotational vibration mode) is changed to the vibration mode 1 (in-plane). A vibration in which the secondary mode (vibration mode) is superimposed is generated in the vibrating body 5. Therefore, the torsional vibration of the vibrating body 5 is not stable, and the optical scanning by the optical scanning devices 1 and 200 is not stable.

  FIG. 35 shows the analysis conditions under which the third numerical analysis was performed. In the third numerical analysis, the length of the connecting portions 17 and 18 of the vibrating body 5 is set to be 2 mm, which is longer than those in the first and second numerical analyses. Therefore, the branch interval L2 is also 2 mm, which is twice as long as 1 mm which is the width L1 of the reflection mirror 8.

  FIG. 36 shows the vibrating body 5 shown in FIG. 35 in a stationary state. The third numerical analysis was performed to simulate the vibrating body 5 in eight different vibration modes. The eight types of vibration modes are different as follows with respect to the vibration frequency at which the vibrating body 5 is vibrated.

Vibration mode 1: 9.0kHz
Vibration mode 2: 12.1 kHz
Vibration mode 3: 15.4kHz
Vibration mode 4: 17.6 kHz
Vibration mode 5: 29.1 kHz
Vibration mode 6: 32.1kHz
Vibration mode 7: 60.4 kHz
Vibration mode 8: 64.2 kHz

  Hereinafter, the result of the third numerical analysis will be described with reference to FIGS.

  Prior to that, the contents of FIGS. 37 to 48 will be briefly described.

  FIGS. 37 to 40 are diagrams each independently showing the analysis result of each vibration mode. Specifically, FIG. 37 is a diagram showing an analysis result of the vibration mode 1, FIG. 38 is a diagram showing an analysis result of the vibration mode 2, and FIG. 39 is a diagram showing an analysis result of the vibration mode 3. FIG. 40 is a diagram illustrating an analysis result of the vibration mode 4.

  FIGS. 41 to 45 are analysis results of the respective vibration modes, which are shown in FIGS. 37 to 40, respectively, for the sake of convenience in comparing with the vibrating body 5 in the stationary state shown in FIG. FIG. Specifically, FIG. 41 is a diagram showing the analysis result of the vibration mode 1 in comparison with the vibration body 5 in the stationary state, and FIG. 42 is a diagram showing the analysis result of the vibration mode 2 in the vibration state 5 in the stationary state. 43 is a diagram showing the analysis result of vibration mode 3 in comparison with the vibrating body 5 in a stationary state, and FIG. 44 is a diagram showing the analysis result of vibration mode 4 in a stationary state. FIG. 9 is a diagram shown in comparison with a certain vibrating body 5.

  Further, FIG. 42 is a diagram solely showing the analysis result of the vibration mode 5, and FIG. 43 is a diagram solely showing the analysis result of the vibration mode 6. FIG. 44 is a diagram illustrating an analysis result of the vibration mode 5 in comparison with the vibration member 5 in a stationary state, and FIG. 45 is a diagram illustrating an analysis result of the vibration mode 6 in comparison with the vibration member 5 in a stationary state. FIG.

  As shown in FIGS. 35 to 48, according to the third numerical analysis result, in the analysis example in which the branch interval L2 is twice the width L1 of the reflection mirror 8, a larger number of results than the second numerical analysis result. It can be seen that the non-torsional vibration mode occurs in a region lower than the frequency of the torsional vibration mode, and therefore, the stability of optical scanning by the optical scanning devices 1 and 200 decreases.

  Considering the results of the three types of numerical analysis described above comprehensively, in the vibrating body 5, the lengths of the connecting portions 17 and 18, that is, the second spring portions 12 and 13 and the second spring portions 15 , 16 are shorter than the width L1 of the reflecting mirror 8, the mass M2 of the connecting portions 17, 18 is reduced, and the swing speed of the reflecting mirror 8 is increased. Of the modes, the occurrence of vibration modes other than the primary horizontal vibration mode (in-plane vibration mode) and the vertical vibration mode (out-of-plane vibration mode) is suppressed. Such a vibration mode is a vibration mode that hinders the linearity of the light reflected from the reflection mirror 8.

  Therefore, if the branch interval L2 is shorter than the width L1, torsional vibration of the vibrating body 5 can occur.

  As described above, the present invention has been described with reference to some embodiments in which the present invention is applied to the optical scanning device used in the image forming apparatus 100. However, a laser printer, a barcode scanner, a projector, or the like performs optical scanning. The present invention can be applied to an optical scanning device used for various devices.

  Further, in some embodiments described above, the vibrating body 5 is directly exposed to the atmosphere. However, the vibrating body 5 is sealed by covering the vibrating body 5 with a cover that can transmit laser light, and the sealed space is large. The present invention can be carried out in a mode in which the pressure is reduced below the atmospheric pressure or the closed space is filled with an inert gas.

  As described above, some of the embodiments of the present invention have been described in detail with reference to the drawings. However, these are exemplifications, and based on the knowledge of those skilled in the art, including the aspects described in the section of [Disclosure of the Invention]. The present invention can be implemented in other forms with various modifications and improvements.

1 is a system diagram showing a retinal scanning image forming apparatus 100 including an optical scanning device 1 according to a first embodiment of the present invention. FIG. 2 is a block diagram of a horizontal scanning drive circuit 121 in FIG. 1. FIG. 2 is a perspective view of the optical scanning device 1 in FIG. FIG. 2 is an exploded perspective view of the optical scanning device 1 in FIG. FIG. 2 is a perspective view for explaining a state of a surface of a reflection mirror 8 of the optical scanning device 1 in FIG. FIG. 5 is a partial side view showing the vibrating body 5 in FIG. 4 when viewed in a width direction. FIG. 5 is a partial side view showing the vibrating body 5 in FIG. 4 as viewed in the width direction and showing in detail the structure of a driving source d in FIG. FIG. 5 is a perspective view showing the vibrating body 5 in FIG. 4 in a resonance state. FIG. 6 is a partial side view showing a comparative example of the second spring portion 13 in FIG. 5. It is sectional drawing for demonstrating calculation of the area moment of inertia of the member which has a rectangular cross section. FIG. 9 is a perspective view illustrating an optical scanning device 200 according to a second embodiment. FIG. 12 is an exploded perspective view showing the optical scanning device 200 shown in FIG. FIG. 12 is a block diagram showing a horizontal scanning drive circuit 121 in the optical scanning device 200 shown in FIG. It is a front view which shows simply the model for numerically analyzing the vibration characteristic of the vibrating body 5 in the said 1st and 2nd embodiment on a 1st numerical analysis condition. FIG. 15 is a perspective view showing the vibrating body 5 shown in FIG. 14 in a stationary state. FIG. 15 is a perspective view showing an analysis result of a vibration mode 1 for the vibrating body 5 shown in FIG. 14. FIG. 15 is a perspective view showing an analysis result of a vibration mode 2 for the vibrating body 5 shown in FIG. 14. FIG. 15 is a perspective view showing an analysis result of a vibration mode 3 for the vibrating body 5 shown in FIG. 14. FIG. 15 is a perspective view showing an analysis result of a vibration mode 4 for the vibrating body 5 shown in FIG. 14. FIG. 15 is a perspective view showing an analysis result of a vibration mode 1 of the vibrating body 5 shown in FIG. 15 is a perspective view showing an analysis result of a vibration mode 2 of the vibrating body 5 shown in FIG. FIG. 15 is a perspective view showing an analysis result of a vibration mode 3 of the vibrating body 5 shown in FIG. 14 superimposed on the vibrating body 5 in a stationary state. 15 is a perspective view showing an analysis result of a vibration mode 4 of the vibrating body 5 shown in FIG. It is a front view which shows simply the model for numerically analyzing the vibration characteristic of the vibrating body 5 in said 1st and 2nd embodiment on a 2nd numerical analysis condition. FIG. 25 is a perspective view showing the vibration body 5 shown in FIG. 24 in a stationary state. 25 is a perspective view showing an analysis result of a vibration mode 1 for the vibrating body 5 shown in FIG. 24. FIG. 25 is a perspective view showing an analysis result of a vibration mode 2 for the vibrating body 5 shown in FIG. 24. FIG. 25 is a perspective view showing an analysis result of a vibration mode 3 for the vibrating body 5 shown in FIG. 24. FIG. 25 is a perspective view showing an analysis result of a vibration mode 4 for the vibrating body 5 shown in FIG. 24. FIG. FIG. 25 is a perspective view showing, with respect to the vibrating body 5 shown in FIG. 24, an analysis result of the vibration mode 1 superimposed on the vibrating body 5 in a stationary state. FIG. 25 is a perspective view showing, with respect to the vibrating body 5 shown in FIG. 24, an analysis result of the vibration mode 2 superimposed on the vibrating body 5 in a stationary state. 25 is a perspective view showing an analysis result of a vibration mode 3 of the vibrating body 5 shown in FIG. 25 is a perspective view showing an analysis result of a vibration mode 4 of the vibrating body 5 shown in FIG. FIG. 9 is a diagram showing an approximate model of the vibrating body 5 in the first and second embodiments together with three types of vibration modes. FIG. 9 is a front view schematically showing a model for numerically analyzing the vibration characteristics of the vibrating body 5 in the first and second embodiments under a third numerical analysis condition. FIG. 36 is a perspective view showing the vibrating body 5 shown in FIG. 35 in a stationary state. 36 is a perspective view showing an analysis result of a vibration mode 1 for the vibrating body 5 shown in FIG. 35. FIG. 36 is a perspective view illustrating an analysis result of a vibration mode 2 for the vibrating body 5 illustrated in FIG. 35. FIG. FIG. 36 is a perspective view showing an analysis result of a vibration mode 3 for the vibrating body 5 shown in FIG. 35. 36 is a perspective view showing an analysis result of a vibration mode 4 for the vibrating body 5 shown in FIG. 35. FIG. 36 is a perspective view showing the analysis result of vibration mode 1 for the vibrating body 5 shown in FIG. 35, superimposed on the vibrating body 5 in a stationary state. FIG. 36 is a perspective view showing an analysis result of a vibration mode 2 for the vibrating body 5 shown in FIG. 35, superimposed on the vibrating body 5 in a stationary state. FIG. 36 is a perspective view showing an analysis result of a vibration mode 3 for the vibrating body 5 shown in FIG. 35, superimposed on the vibrating body 5 in a stationary state. FIG. FIG. 36 is a perspective view showing, with respect to the vibrating body 5 shown in FIG. 35, an analysis result of the vibration mode 4 superimposed on the vibrating body 5 in a stationary state. 36 is a perspective view showing an analysis result of a vibration mode 5 for the vibrating body 5 shown in FIG. 35. FIG. 36 is a perspective view showing an analysis result of a vibration mode 6 for the vibrating body 5 shown in FIG. 35. FIG. FIG. 36 is a perspective view showing an analysis result of a vibration mode 5 of the vibrating body 5 shown in FIG. 35, superimposed on the vibrating body 5 in a stationary state. FIG. 36 is a perspective view showing, with respect to the vibrating body 5 shown in FIG. 35, analysis results of the vibration mode 6 superimposed on the vibrating body 5 in a stationary state.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Optical scanning device 5 Vibration body 7 Fixed frame part 8 Reflection mirror 9,10 First spring part 12,13,15,16 Second spring part 17,18 Connecting part 100 Image forming apparatus 102 Vertical scanning system 103 Horizontal scanning System 106 Light source a, b, c, d Drive source

Claims (22)

By vibrating at least a part of a vibrating body having a reflection mirror unit, an optical scanning device that scans light by changing a reflection direction of light incident on the reflection mirror unit,
The vibrator,
A first spring unit connected to the reflection mirror unit and generating torsional vibration;
The first spring portion is connected to the fixed frame portion of the vibrating body at a branch interval wider than the width of the first spring portion, and bending vibration and torsional vibration are generated. A plurality of second spring portions,
A plurality of driving sources for respectively oscillating the plurality of second springs;
An optical scanning device in which, among the vibrators, a second moment of area in an elastically deformable portion composed of each of the second spring portions and each of the driving sources corresponding to each other is smaller than the second moment of area of the first spring portion. By vibrating at least a part of a vibrating body having a reflection mirror unit, an optical scanning device that scans light by changing a reflection direction of light incident on the reflection mirror unit,
The vibrator,
A first spring unit connected to the reflection mirror unit and generating torsional vibration;
The first spring portion is connected to the fixed frame portion of the vibrating body at a branch interval wider than the width of the first spring portion, and bending vibration and torsional vibration are generated. A plurality of second spring portions, and
Each of the second spring portions has the same elastic modulus as the first spring portion, but has a cross-sectional shape that is more easily elastically deformed than the first spring portion,
The optical scanning device further includes a driving source that vibrates the plurality of second springs.   The optical scanning device according to claim 1, wherein the branch interval does not exceed a width of the reflection mirror unit.   4. The optical scanning device according to claim 1, wherein the plurality of second spring portions generate bending vibration in a plane parallel to each plate thickness direction. 5.   The optical scanning device according to claim 4, wherein the plurality of second spring portions generate bending vibrations in mutually opposite phases.   The optical scanning device according to claim 5, wherein the plurality of second spring portions generate bending vibrations in opposite phases to each other by a mechanical force.   The optical scanning device according to claim 6, wherein the drive source is mounted on a target spring portion that is at least one of the plurality of second spring portions.   The optical scanning device according to claim 7, wherein the drive source is fixed to at least one target surface of both surfaces of the target spring portion.   9. The drive source is fixed to the target surface in such a manner that the drive source straddles the target surface and a portion corresponding to the target surface among two surfaces of a portion of the fixed frame portion adjacent to the target spring portion. 3. The optical scanning device according to claim 1.   The optical scanning device according to claim 8, wherein the driving source is fixed to the target surface by a thin film forming method.   The optical scanning device according to claim 10, wherein the thin film forming method is any one of CVD, sputtering, hydrothermal synthesis, sol-gel, and fine particle spraying.   The optical scanning device according to claim 7, wherein the drive source extends along the target spring portion, and expands and contracts in a direction in which the drive source extends.   The optical scanning device according to claim 2, wherein the drive source directly vibrates the vibrator.   The optical scanning device according to claim 2, wherein the drive source indirectly vibrates the vibrator.   The optical scanning device according to claim 1, wherein the drive source vibrates the vibrating body at a frequency equal to a resonance frequency thereof. The reflection mirror unit is caused to swing around a swing axis by the torsional vibration,
The vibrating body further includes a connecting portion that connects the first spring portion and the plurality of second spring portions to each other, and the first spring portion, the plurality of second spring portions, and the connecting portion. And constitute a connected body,
The optical scanning device according to any one of claims 1 to 15, wherein the connecting members are arranged on the vibrating member at two opposing positions opposing each other in the direction of the oscillation axis with the reflection mirror portion interposed therebetween. apparatus.   17. The optical scanning device according to claim 16, wherein the two connected bodies respectively disposed at the two opposing positions are symmetrically disposed with respect to the position of the reflection mirror unit.   18. The vibration body according to claim 1, further comprising a connecting portion that connects the first spring portion and the plurality of second spring portions to each other, wherein the driving source is not mounted on the connecting portion. The optical scanning device according to any one of the above.   The vibrating body further includes a connecting portion that connects the first spring portion and the plurality of second spring portions to each other, and the connecting portion includes the first spring portion and the plurality of second spring portions. 19. The optical scanning device according to claim 1, wherein the optical scanning device is connected to the two spring portions at substantially right angles. An image forming apparatus that forms an image by scanning a light beam,
A light source for emitting the light beam;
20. An image forming apparatus comprising: the optical scanning device according to claim 1; and a scanning unit that scans a light beam emitted from the light source by using the optical scanning device.   The scanning unit performs a first scan that scans the light beam in a first direction and a second scan that scans at a lower speed than the first scan in a second direction that intersects the first direction. The image forming apparatus according to claim 20, wherein an optical scanning device is used for performing the first scanning. 22. The image forming apparatus according to claim 20, further comprising an optical system that guides a light beam scanned by the scanning unit toward a retina of an observer.

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