JP2007010823A - Driven mirror, light scanning optical apparatus and picture display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driven mirror which is turnably furnished so as to scan a light beam emitted from a light source, in which a desired apparatus durability is available even when the speed of the mirror is high and the oscillation angle of the mirror is increased, and to provide a light scanning optical apparatus and a picture display apparatus furnished with the driven mirror. <P>SOLUTION: The driven mirror 22 comprises a mirror part 24, a beam 25 for supporting the mirror part 24, a fixed frame 26 for supporting the beam 25, arm parts 27a to 27d provided for turning the beam 25, and piezoelectric films 28 provided on the arm parts 27a to 27d. In this case, the pair of arm parts 27a and 27b, and the pair of arm parts 27c and 27d compose driving arms 29a and 29b, respectively. When an electric voltage is applied on the piezoelectric body 28, the driving arms 29a and 29b are dislocated by the expansion and the contraction of the piezoelectric body 28, and torque is generated on the beam 25. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a drive mirror that scans light from a light source used in projectors, laser beam printers, and the like, and more particularly to a small drive mirror that can perform one-dimensional light scanning at high speed. The present invention also relates to an optical scanning optical apparatus that can scan light in a predetermined direction at a high speed by including such a drive mirror and can reduce the size of the entire apparatus. Furthermore, the present invention relates to an image display device including such a drive mirror and an optical scanning optical device.

  In an image display device or the like, a light beam from a light source is two-dimensionally scanned when displaying an image on a screen or the like. In this regard, as a method of scanning a light beam in two dimensions, a method of combining two galvanometer mirrors that scan a light beam in one dimension, a method of combining two polygon mirrors, or the like is known.

  However, in the case of a system in which a light beam from a light source is scanned by combining two galvanometer mirrors or the like, there is a problem that the overall size of the image display apparatus increases. In addition, there is a problem that the design is very difficult because the positional relationship between the two galvanometer mirrors and the like needs to be precisely adjusted.

  For this reason, in Patent Document 1, for example, a mirror part formed of a silicon substrate that reflects laser light and can be displaced in the X-axis and Y-axis directions, and a beam formed of a silicon substrate that supports the mirror part from both sides And a two-dimensional scanning type optical scanner that drives the mirror portion by an electrostatic method. Patent Document 2 introduces a two-dimensional MEMS scanner capable of optical scanning in the X and Y directions and scanning a mirror by an electromagnetic drive method. If these optical scanning devices are used, the size of an image display device or the like can be reduced.

  However, in these two-dimensional scanning type optical scanners, for example, when the light beam from the light source is scanned in the horizontal direction and the vertical direction, the driving methods in the horizontal direction and the vertical direction are the same. Therefore, it is difficult to provide a large difference in scanning speed. For this reason, when an image is displayed on a display unit such as a screen using the two-dimensional scanning optical scanner, it is difficult to obtain a high resolution in the vertical direction. In particular, when driven by an electrostatic method, there is a problem that it is difficult to drive a large mirror because the generated force is small. Further, such a two-dimensional scanning light scanner is manufactured from a single wafer by the gimbal method, but in this case, there is a problem that the manufacturing process becomes complicated.

  As another two-dimensional optical scanning device, a light beam from a light source can be obtained by rotating, driving, and swinging an electromagnetically driven one-dimensional optical scanning device in Patent Document 3 with a separate drive device. There has been proposed an apparatus for two-dimensional scanning. According to this, since the driving method differs depending on the light scanning direction, it is possible to make a difference in scanning speed between the horizontal direction and the vertical direction. However, when the one-dimensional optical scanning device is driven by an electromagnetic driving method or an electrostatic method, there are large restrictions on the scanning speed of the mirror, the size of the mirror, and the like. For example, a problem occurs when trying to obtain a high-resolution image. There is a case.

In this regard, in Patent Document 4, a driving method using a piezoelectric body is used as a driving method of the optical scanning device, and by adding a device to the configuration of the spring portion, while maintaining the resonance frequency of the reflection mirror portion at a high frequency, A high-speed optical scanning device that performs one-dimensional optical scanning capable of obtaining a sufficient twist angle has been proposed. When this apparatus is used, the mirror size is 1 mm × 1 mm and the scanning frequency of the mirror part is 25 kHz. However, in the case of the high-speed optical scanning device proposed in Patent Document 4, if the mirror size is increased, a large frequency cannot be achieved (this will be described later), the mirror speed, the mirror angle, and the durability of the optical scanning device itself. There is a problem that it is difficult to obtain an optical scanning device having a configuration satisfying all of the above.
JP-A-6-180428 JP 2005-502910 A Japanese Patent Laid-Open No. 2004-4276 JP 2004-177543 A

  In view of the above problems, an object of the present invention is to increase the mirror speed and increase the mirror deflection angle in a drive mirror provided with a mirror that can be rotated so that a light beam emitted from a light source can be scanned. Even so, it is an object to provide a drive mirror that can satisfy the requirement of device durability. Another object of the present invention is to provide a compact optical scanning optical system that includes a driving mirror that rotates at a high speed, has a large mirror deflection angle, and can satisfy durability, and that can perform optical scanning at high speed in a predetermined direction. Is to provide a device. A further object of the present invention is to provide a compact optical scanning optical device that can perform optical scanning in two dimensions and can provide a large difference in scanning speed in two scanning directions. Furthermore, another object of the present invention is to provide a small image display device capable of displaying a high resolution image.

  In order to achieve the above object, a drive mirror according to a first aspect of the present invention includes a mirror portion provided with a reflecting surface for reflecting light, a beam for holding the mirror portion, a fixing portion for fixing the beam, and the beam. And a drive mirror that is rotated by expansion and contraction of the piezoelectric element, wherein the drive unit has at least one drive arm including two arm parts coupled to the beam so as to sandwich the beam. The arm portions are arranged substantially perpendicular to the beam, and each of the arm portions is provided with the piezoelectric element.

  According to a second aspect of the invention, in the configuration of the first aspect, the drive mirror is characterized in that the piezoelectric element is provided on the back surface side of the arm sandwiching the beam.

  According to a third aspect of the invention, in the configuration of the first or second aspect of the invention, the arm portion is provided substantially in parallel with the reflecting surface.

  According to a fourth aspect of the present invention, there is provided the drive mirror according to any one of the first to third aspects, wherein the two arm portions are provided substantially in point symmetry with respect to the cross-sectional center of the beam. It is a feature.

  According to a fifth aspect of the invention, in the drive mirror according to any one of the first to fourth aspects of the invention, the drive unit has two drive arms, and the drive arm sandwiches the mirror unit. It is characterized by being provided symmetrically.

  According to a sixth aspect of the present invention, in the drive mirror according to any one of the first to fifth aspects of the invention, the fixed portion is disposed so as to surround the mirror portion, and one end of the arm portion is the fixed portion. It is connected to.

  According to a seventh aspect of the present invention, there is provided a drive mirror according to any one of the first to sixth aspects, wherein the mirror portion is provided so as to vibrate by resonance.

  According to an eighth aspect of the present invention, there is provided an optical scanning optical apparatus including the drive mirror having the structure according to any one of the first to seventh aspects.

  According to a ninth aspect of the present invention, there is provided an optical scanning optical device comprising: a light source; a collimating optical system that converts light emitted from the light source into parallel light; and a reflecting surface that reflects light that has passed through the collimating optical system. In the optical scanning optical apparatus comprising: an optical scanning unit that scans light two-dimensionally by driving a mirror unit; and a projection optical system that guides the light scanned by the optical scanning unit to a display unit. The two-dimensional optical scanning of the part is performed by rotating the mirror part around two rotation axes that pass through the approximate center of the reflection surface and are parallel to the reflection surface and orthogonal to each other. One of the rotational driving is performed by a driving mirror having the mirror portion and capable of optical scanning in one dimension, and the other is performed by using an entire driving device that integrally rotates the entire driving mirror. .

  An optical scanning optical device according to a tenth aspect of the invention is characterized in that, in the configuration of the ninth aspect of the invention, the drive mirror is the drive mirror according to any one of claims 1 to 7.

  An optical scanning optical apparatus according to an eleventh aspect of the invention is characterized in that, in the configuration of the ninth or tenth aspect of the invention, the overall driving device is step-driven.

  An optical scanning optical device according to a twelfth aspect of the invention is the configuration according to the eleventh aspect of the invention, wherein the overall driving device is connected to the driving mirror and a rotation shaft connected to the driving mirror and capable of rotating the driving mirror. And a rotation drive unit that rotates the rotation shaft, and the rotation drive unit is fixed on the base and is subjected to expansion and contraction vibration with a predetermined phase difference. And a tip portion that is pressed against the rotation shaft while generating elliptical rotation by connecting both displacement portions.

The optical scanning optical device according to a thirteenth aspect of the invention is the configuration of the twelfth aspect of the invention, wherein the rotation amount of the rotation shaft when the tip portion makes one elliptical rotation is A, When the light is scanned by driving and the amount of rotation of the rotating shaft necessary to move the image on the display unit by one pixel in the light scanning direction is B, the following equation (A) is satisfied. It is a feature.
B / A> 3 (A)

  According to a fourteenth aspect of the present invention, in the optical scanning optical apparatus according to any one of the ninth to thirteenth aspects, the projection optical system has a projection method in each of two directions in which the optical scanning unit performs optical scanning. It is characterized by being provided differently.

An optical scanning optical device according to a fifteenth aspect of the invention is the configuration according to the fourteenth aspect of the invention, wherein the projection method uses a focal length of the projection optical system as f (mm) and the center of the light beam toward the center of the display unit. Incident light that is reflected by the mirror unit and incident on the projection optical system with a light beam as an optical axis is parallel to a first direction that includes the optical axis and that performs optical scanning by the drive mirror in the two directions. When projected, the angle formed by the projected light and the optical axis is θ (rad), the maximum value that θ can take is θmax, the incident light includes the optical axis, and the second of the two directions includes the optical axis. When projected onto a plane parallel to a second direction different from the first direction, the angle formed by the projected light with the optical axis is φ (rad), and the second part passes through the center of the display unit on the display unit. The straight line orthogonal to the direction 1 and the incident light are projected onto the display unit. The distance between the image to be created is y1 (mm), the distance between the straight line passing through the center of the display unit and perpendicular to the second direction and the image created by projecting the incident light onto the display unit is y2 (mm), When a and k are predetermined coefficients, the projection methods in the first direction and the second direction are expressed by the following equations (B) and (C), respectively.
y1 = a · arcsin (k · θ / θmax) (B)
y2 = f · φ (C)

  An optical scanning optical device according to a sixteenth aspect of the invention is characterized in that, in the configuration of the fourteenth or fifteenth aspect, an anamorphic aspherical lens or a free-form surface lens is used for the projection optical system. Yes.

  According to a seventeenth aspect of the present invention, in the configuration of any one of the ninth to sixteenth aspects, a color combining prism is disposed between the light source and the optical scanning unit. It is said.

  According to an eighteenth aspect of the present invention, an image display apparatus includes the drive mirror according to any one of the first to seventh aspects.

  According to a nineteenth aspect of the present invention, there is provided an image display device for inputting an image signal, a luminance signal conversion unit for converting the image signal input to the image signal input unit into a luminance signal, and the luminance signal conversion. A light control unit comprising: a light source luminance control unit that controls the intensity of the light source based on the luminance signal converted by the unit; and a light source frequency modulation unit that modulates a frequency of light emitted from the light source, 18. The optical scanning optical device according to claim 17, wherein the driving mirror is used for horizontal light scanning of the display unit, and the whole driving device is used for vertical light scanning of the display unit. The horizontal scanning speed is higher than the vertical scanning speed.

An image display device according to a twentieth aspect of the present invention is the image display device according to the nineteenth aspect of the invention, wherein Vx and Vy are expressed by the following equations when the horizontal scanning speed is Vx and the vertical scanning speed is Vy: D) is satisfied.
Vx / Vy> 500 (D)

  An image display apparatus according to a twenty-first aspect is characterized in that, in the configuration of the nineteenth or twentieth aspect, the vertical scanning frequency is higher than 50 Hz.

  According to a twenty-second aspect of the present invention, in the configuration of any one of the nineteenth to twenty-first aspects, the light source frequency modulation section is provided between the horizontal direction center side and the end side of the display section. It modulates so that the frequency of the light radiate | emitted from the said light source may differ.

  According to the configuration of the first aspect of the present invention, in the drive mirror provided with the mirror unit rotatably, the drive unit that rotates the mirror unit can rotate the mirror at high speed because the drive unit that rotates the mirror unit is a piezoelectric drive system. Moreover, the load applied to the device when the piezoelectric element is driven can be dispersed, and even if the width of the beam is increased to ensure durability, the amount of displacement of the drive unit required to rotate the mirror unit does not change. With this configuration, it is possible to realize a drive mirror that satisfies all of the increase in the scanning speed of the mirror, the increase in the deflection angle of the mirror, and the high durability of the apparatus.

  Further, according to the configuration of the second invention, in the drive mirror having the configuration of the first invention, the piezoelectric element can be easily arranged, and a larger piezoelectric element can be arranged than when arranged on the side sandwiching the beam. Therefore, the driving force for driving the mirror unit can be increased.

  According to the configuration of the third aspect of the invention, in the drive mirror having the configuration of the first or second aspect of the invention, since the drive mirror can be made flat, the overall size of the drive mirror can be made compact. It becomes easy to process.

  Further, according to the configuration of the fourth aspect of the invention, in the drive mirror having the configuration of any one of the first to third aspects of the invention, a structure that can stably support the beam that holds the mirror portion can be obtained. A drive mirror with excellent performance can be realized.

  According to the configuration of the fifth invention, in the drive mirror having the configuration of any one of the first to fourth inventions, the drive unit for rotating the beam provided to hold the mirror unit is provided on the mirror unit. Since they are provided symmetrically on both sides, the voltage applied to each drive unit can be reduced, and the load on each drive unit can be reduced. Further, since the structure of the drive mirror has a stable shape, it is possible to improve durability.

  According to the configuration of the sixth invention, in the drive mirror having the configuration of any of the first to fifth inventions, there is no need to separately provide a fixing portion for attaching the drive unit, and there is an extra number of parts. An increase can be avoided. Further, since the drive mirror can be configured flat, the size of the drive mirror as a whole can be made compact, and the process can be easily processed.

  According to the configuration of the seventh aspect of the invention, in the drive mirror having the configuration of any one of the first to sixth aspects of the invention, since the vibration of the mirror portion is resonance, the deflection angle of the mirror portion is low in power consumption. It becomes possible to obtain a drive mirror having a large.

  According to the configuration of the eighth invention, in the optical scanning device that scans the light beam emitted from the light source, the mirror portion rotates at a high speed, the deflection angle of the mirror portion is large, and the durability is high. Since the driving mirror capable of scanning in dimension is provided, it is possible to obtain an optical scanning device corresponding to high speed.

  According to the ninth aspect of the invention, in the optical scanning optical device that optically scans the light beam emitted from the light source two-dimensionally and guides the light to the display unit using the projection optical system, the optical scanning unit Since the optical scanning driving method is different in the two directions in which the optical scanning is performed, it is possible to provide a large difference in the optical scanning speed in the two directions. Even if the driving method is separate driving, optical scanning in two directions is performed by a method in which the mirror portion is rotated about two axes passing through the center of the reflecting surface and parallel to the reflecting surface and orthogonal to each other. Therefore, the pupil can be arranged in the vicinity of the reflecting surface, and the entire optical scanning optical device does not become large.

  According to the configuration of the tenth aspect of the invention, in the optical scanning optical device of the configuration of the ninth aspect of the invention, a driving mirror that can rotate at high speed is used for one of the two directions of optical scanning by the optical scanning unit. Therefore, it becomes easy to provide a large difference in the optical scanning speed in each direction.

  According to the configuration of the eleventh aspect of the invention, in the optical scanning optical device of the configuration of the tenth aspect, every time the drive mirror scans a predetermined amount in one direction, the whole drive device is used in the other direction. A configuration for scanning can be realized.

  According to the configuration of the twelfth aspect of the invention, in the optical scanning optical device of the configuration of the eleventh aspect of the invention, since the size of the entire drive device can be designed compactly, the size of the entire two-dimensional type optical scanning device Can be miniaturized.

  According to the configuration of the thirteenth aspect of the invention, in the optical scanning optical device of the configuration of the twelfth aspect of the invention, since the optical scanning by the whole driving device is set to be performed step by step, the whole driving device Even if an error occurs in the amount of rotation of the tip portion of the rotation of the rotating shaft by one rotation, it is easy to correct the error.

  According to the fourteenth aspect of the invention, in the optical scanning optical device according to any one of the ninth to thirteenth aspects of the invention, the optical scanning drive system in each of the two directions in which the optical scanning unit scans the light. If they are different, distortion may occur in an image projected on a display unit such as a screen, but the distortion can be eliminated by the optical system.

  According to the configuration of the fifteenth aspect of the invention, in the optical scanning optical apparatus of the configuration of the fourteenth aspect of the invention, the scanning speed of the light in the two directions scanned by the optical scanning unit is such that one optical scanning is resonantly driven, The asymmetric distortion generated when the optical scanning is step driven can be eliminated by the optical system.

  According to the configuration of the sixteenth aspect of the invention, in the optical scanning optical device of the configuration of the fourteenth or fifteenth aspect, it is possible to eliminate distortion due to a difference in the optical scanning drive system with a reduced number of parts. Further, when a free-form surface lens is used, in addition to the above-described distortion, it is possible to eliminate trapezoidal distortion that may occur when light is incident on a mirror that performs optical scanning at a finite angle. .

  According to the configuration of the seventeenth invention, in the optical scanning optical device having the configuration of any of the ninth to sixteenth inventions, when there are a plurality of light sources having different wavelengths, the light emitted from the plurality of light sources Can be synthesized. Further, light beams having different wavelengths emitted from a plurality of light sources can be synthesized with a small number of parts.

  According to the eighteenth aspect of the invention, since the drive mirror according to any one of claims 1 to 7 is provided, a high-resolution image display device can be obtained.

  According to the nineteenth aspect of the invention, since the optical scanning device according to any of the ninth to seventeenth aspects of the invention is provided, a high-resolution and small-sized image display device can be obtained. Become.

  According to the twentieth aspect of the invention, in the nineteenth aspect of the invention, since the horizontal optical scanning speed is set larger than the vertical optical scanning speed, the vertical resolution is low. As a result, the image quality of VGA (horizontal 640 × vertical 480 dots) and HDTV (horizontal 1920 × vertical 1080 dots) can be obtained.

  According to the twenty-first aspect of the invention, in the nineteenth or twentieth aspect of the invention, the image display cycle (frame rate) is set short, so that a good image can be obtained. Can move smoothly.

  According to the structure of the twenty-second invention, in the structure of any one of the nineteenth to twenty-first inventions, it is possible to correct image distortion not only by the optical system but also by electric control.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an example of an embodiment of an image display device provided with a drive mirror and an optical scanning optical device of the present invention. FIG. 1 is a block diagram showing a schematic configuration of the image display apparatus of the present embodiment. In FIG. 1, an image display device 1 receives an image signal output from, for example, a personal computer or a television, and scans light in response to a light control unit 2 that performs processing and a signal output from the light control unit 2. For example, the optical scanning optical device 3 projects light onto the display unit 15 such as a screen or a wall.

  FIG. 2 is a schematic perspective view showing the appearance of the optical scanning optical device 3. As shown in the figure, the optical scanning optical device has, for example, a rectangular parallelepiped shape or a cubic shape. The optical scanning optical device 3 can be configured to be ultra-small, and for example, the lengths in the vertical, horizontal, and depth directions in the figure can be designed within 30 mm.

  As shown in FIG. 1, the optical scanning optical device 3 includes three light sources 4 to 6 corresponding to red, green, and blue (hereinafter abbreviated as RGB), a color synthesizing prism 7, a collimator lens 8, and the like. , An optical scanning unit 9, a projection optical system 10, a mirror position detection light source 12, a mirror position detection means 13, and an optical scanning control unit 14.

  The light emitted from the three light sources 4 to 6 corresponding to RGB passes through the color synthesis prism 7 and the collimator lens 8 in this order, and is optically scanned by the optical scanning unit 9 and transmitted through the projection optical system 10. For example, an image is formed on the display unit 15 such as a screen or a wall.

  Next, details of each part in the image display device 1 will be described. First, the light control unit 2 will be described with reference to FIGS. 1 and 3. FIG. 3 is a block diagram illustrating a configuration of the light control unit 2. As shown in FIG. 3, the light control unit 2 includes an image signal input unit 16, a luminance signal conversion unit 17, a light source luminance control unit 18, and a light source frequency modulation unit 19.

  The image signal input unit 16 is a part that inputs and processes an image signal output from a medium such as a personal computer or a television. The image signal input to the image signal input unit 16 is sent to the luminance signal conversion unit 17 where it is converted into a luminance signal. The light source luminance control unit 18 supplies drive signals to the RGB light sources 4 to 6 so that the RGB light sources 4 to 6 can generate light whose intensity is modulated based on the luminance signal converted by the luminance signal conversion unit 17. . Note that the intensity modulation of the light source based on the signal supplied from the light source luminance control unit 18 is performed by directly modulating the current supplied to the light source.

  The light source frequency modulation unit 19 determines the frequency of light emitted from the light sources 4 to 6 based on the relationship between the scanning speed at which the light scanning unit 9 scans light and the resolution of the image projected on the display unit 15 such as a screen. Then, the signal is supplied to the light sources 4-6. In addition to this, the optical control unit 2 controls the movement of the optical scanning unit 9 that performs optical scanning in the horizontal direction (left and right direction in FIG. 1) and the vertical direction (paper surface direction in FIG. 1) of the display unit 15. 14 and a synchronization signal necessary for synchronizing the scanning operation is supplied. The light control unit 2 is also connected to the mirror position detection unit 13, and controls the timing of emitting light from the light sources 4 to 6 based on a signal supplied from the mirror position detection unit 13.

  Next, details of the optical scanning optical device 3 will be described. As shown in FIG. 1, the light sources 4 to 6 are provided with three light sources. For example, the light source 4 is a red semiconductor laser diode, the light source 5 is a green semiconductor laser diode, and the light source 6 is a blue semiconductor laser diode. Correspond. The wavelengths of the respective semiconductor laser diodes are set to, for example, 660 nm for red, 532 nm for green, and 450 nm for blue.

  In this embodiment, a semiconductor laser diode is used as the light source. However, the present invention is not limited to this, and can be changed without departing from the object of the present invention. In particular, since a green semiconductor laser diode is difficult to obtain, a DPSS (Diode Pumping Solid State) laser that excites a crystal with a semiconductor laser only in green may be modulated with an external modulator. Further, for all colors of red, green, and blue, a light emitting diode (LED), a solid state laser, or the like may be used as a light source instead of the semiconductor laser diode. However, the size of the light source is preferably small, and a semiconductor laser diode is preferable in that respect.

  The color synthesizing prism 7 plays a role of synthesizing the laser beams emitted from the light sources 4 to 6, and the laser beams emitted from the light sources 4 to 6 are synthesized here, and the synthesized color is displayed on the display unit 14 such as a screen. To display. In the present embodiment, a color synthesis prism is used, but the present invention is not limited to this. For example, as shown in FIG. 4, two dichroic mirrors 20 and 21 are used to synthesize laser beams emitted from red and green light sources 4 and 5 with a dichroic mirror 20 that reflects red light and transmits green light. Thereafter, the dichroic mirror 21 that reflects blue light and transmits red light and green light is used to combine the laser light emitted from the blue light source 6 with the previously synthesized laser light. I do not care. However, it is preferable to use the color synthesizing prism 7 in terms of reducing the number of parts of the apparatus and reducing the size of the entire apparatus.

  The collimator lens 8 is a lens that converts divergent light emitted from the light sources 4 to 6 and passing through the color synthesis prism 7 into parallel light. The collimator lens 8 is adjusted in focus so as to correct chromatic aberration generated in the projection optical system 10.

  The optical scanning unit 9 can scan the laser light that has passed through the collimator lens 9, and in the present embodiment, the horizontal direction (the left-right direction in FIG. 1) and the vertical direction (with respect to the display unit 15 such as a screen) Laser light is scanned in the direction of the paper surface of FIG. FIG. 5 is a schematic perspective view showing the optical scanning unit 9 of the present embodiment. As shown in FIG. 5, the optical scanning unit 9 includes a drive mirror 22 that can scan light in one dimension and an overall drive device 23 that rotates the drive mirror 22 as a whole around a rotation shaft 31. Is done.

  The light scanning unit 9 scans light in the horizontal direction and the vertical direction by using a mirror unit 24 provided in the drive mirror 22. That is, the mirror unit 24 rotates when the beam 25 included in the drive mirror 22 is rotated by the drive of the drive mirror 22 itself, and also rotates when the entire drive mirror 22 is rotated by the overall drive device 23. Is done. At this time, the beam 25 and the center line 31a of the rotating shaft 31 that rotates the entire drive unit 23 pass through the approximate center of the reflecting surface (front side of the drawing) of the mirror portion 24, and are mutually parallel on a surface parallel to the reflecting surface. It is set to be orthogonal. Therefore, by setting the beam 25 to be scanned in the horizontal direction by the rotation of the beam 25 by the drive mirror 22, the light is scanned in the vertical direction when the entire drive mirror 22 is rotated by the overall drive device 23. Below, the detail of the drive mirror 22 and the whole drive device 23 is demonstrated.

  First, details of the drive mirror 22 will be described with reference to FIGS. FIG. 6A is a schematic diagram showing the configuration of the drive mirror 22 of the present embodiment, and is a front view seen from the reflection surface side where the mirror unit 24 performs optical scanning. FIG. 6B is a view of the AA ′ cross section of FIG. FIG. 6C is a view seen from the lower side of the figure except for the fixed frame 26 of FIG.

  As shown in FIGS. 6A and 6C, the drive mirror 22 rotates the mirror 24, the beam 25 that holds the mirror 24, the fixed frame 26 that supports the beam 25, and the beam 25. For this purpose, the arm portions 27a to 27d are provided, and the piezoelectric film 28 is provided on the arm portions 27a to 27d. The arm 27a and the arm 27b, and the arm 27c and the arm 27d constitute a pair of drive arms 29a and 29b, respectively.

  As shown in FIG. 6A, the mirror part 24 is formed in a rectangular or square rectangular shape, and is arranged at substantially the center of the fixed frame 26. The surface of the mirror part 24 is provided with a reflective layer 24a such as Au or Al (see FIG. 6C) so that light can be reflected. In the present embodiment, the mirror portion 24 is rectangular, but the present invention is not limited to this.

  The beam 25 extends in the left-right direction in FIG. 6A, supports the mirror portion 24 so as to pass through the approximate center of the mirror portion 24, and both ends thereof are fixed to the fixed frame 26. Then, arm portions 27 a to 27 d are attached to the beam 25 so as to be substantially orthogonal to the beam 25 and substantially parallel to the mirror portion 24. As shown in FIG. 6B, the arm portion 27 a and the arm portion 27 b that form the drive arm 29 a are provided approximately point-symmetrically with respect to the center in the cross-sectional direction of the beam 25. This also applies to the arm portions 27c and 27d that form the drive arm 29b. Further, the drive arm 29 a and the drive arm 29 b are provided at symmetrical positions with respect to the mirror portion 24.

  As shown in FIG. 6C, the piezoelectric film 28 is provided on the upper surface of the arm portion as shown in FIG. 6C, while the arm portions 27b and 27d are provided on the lower surface of the arm portion. That is, when viewed in drive arm units (for example, the case of the arm portion 29a), the piezoelectric film 28 is disposed on the surface opposite to the surface where the arm portions 27a and 27b are connected to the beam 25. For example, PZT, ZnO, BST, or the like is used as the piezoelectric film 28 disposed on the arm portions 27a to 27d. Note that the piezoelectric film 28 is sandwiched between electrode layers (not shown), and thereby expands and contracts when a voltage is applied.

  Next, an example of a method for manufacturing the drive mirror 22 will be described with reference to FIG. FIG. 7 is a view showing a method for manufacturing the drive mirror 22, and is a cross-sectional view of the drive mirror cut along the BB chain line in FIG. Needless to say, the manufacturing method of the drive mirror 22 is not limited to the method shown here.

  The drive mirror 22 is produced using, for example, a silicon base material. First, the front and back surfaces of the silicon base material are processed by photoresist and etching so that the mirror part 24, the beam 25, and the arm parts 27a to 27d shown in FIG. 6 are formed (process a and process b). Next, a reflective layer 24a such as Au or Al is formed on the mirror portion 24 on the silicon substrate surface side (step c). Next, the lower electrode layer 30b, the piezoelectric film 28, and the upper electrode layer 30a are formed in this order on the surface side of the silicon substrate (step d). Further, similarly, from the back surface side of the silicon substrate, the lower electrode layer 30b to the upper electrode layer 30a are sequentially formed (step e). Thereby, the drive mirror 22 is formed.

  In addition, examples of the thin film formation method from step c to step e include a sputtering method, a chemical vapor deposition method (CVD method), a sol-gel method, an aerosol deposition method (AD method), and the like, but the aerosol deposition method is preferable. According to this, compared with sputtering method, CVD method, sol-gel method, an etching process etc. can be omitted, and the film-forming speed can be improved and the process can be shortened. The aerosol deposition method is a technology that forms fine particles prepared by other methods in advance by mixing them with gas to form an aerosol, which is then sprayed onto a substrate through a nozzle in a reduced-pressure atmosphere to form a coating. Is shown.

  Next, the operation of the drive mirror 22 will be described with reference to FIG. FIG. 8 is a schematic diagram for explaining the movement of the drive mirror 22 and shows how the piezoelectric film 28 expands and contracts when a voltage is applied to the piezoelectric film 28 of the drive arm 29a. FIG. 8A shows a state in which no voltage is applied to the piezoelectric film 28 and the mirror portion 24 (see FIG. 6) is also stationary.

  FIG. 8B shows a state in which a voltage is applied between the electrodes 30a and 30b (see FIG. 7) and the piezoelectric body 28 extends. When the piezoelectric film 28 is stretched, tensile loads are generated on the arm portions 27a and 27b, respectively, and the arm portions 27a and 27b tend to stretch in the direction of the arrow in the figure. Therefore, the beam 25 existing between the arm portions 27a and 27b rotates counterclockwise in the figure, and the mirror portion 24 also rotates in the same direction at the same time.

  On the other hand, FIG. 8C shows a state where a voltage opposite to that in FIG. 8B is applied and the piezoelectric film 28 is contracted. When the piezoelectric film 28 contracts, a compression load is generated on each of the arms 27a and 27b, and the arms 27a and 27b tend to bend as shown in the figure. For this reason, the beam 25 present between the arm portions 27a and 27b rotates in the clockwise direction in the figure, and the mirror portion 24 also rotates in the same direction at the same time.

  When a voltage having a predetermined frequency is applied to the electrodes, the piezoelectric film 28 repeats expansion and contraction. Therefore, the mirror portion 24 vibrates around the beam 25 so as to swing in a plus direction and a minus direction by a predetermined angle. In the present embodiment, the mirror unit 24 is set to resonate. As a result, the scanning angle of the large mirror unit 24 can be increased with less power consumption.

  The drive mirror 22 of the present embodiment has a structure that can satisfy all of the scanning speed, scanning angle, and durability of the mirror unit 24 at a high level. This point will be described using calculation results. Here, for the sake of convenience, portions indicated by ellipses C, D, and E in FIG. 9 are expressed as a first torsion bar, a second torsion bar, and a third torsion bar, respectively. In the calculation, the size of the mirror portion 24 is 4 mm in length and 3 mm in width as shown in FIG. As a comparison of calculations, the case of the configuration of Patent Document 4 shown in FIG. 10 will also be described. Portions indicated by ellipses F, G, and H in FIG. 10 are expressed as a first torsion bar, a second torsion bar, and a third torsion bar, respectively. The size of the mirror section 24 in FIG. 10 is the same as that in FIG.

  First, the calculation regarding the drive mirror 22 of this embodiment is demonstrated. In the configuration of the drive mirror 22 of this embodiment, the resonance frequency fn is calculated from the spring stiffness k obtained by adding the moment of inertia J of the mirror, the torsional stiffness of the first torsion bar, and the bending stiffness of the second torsion bar. The relational expression is shown below.

Here, kn is a vibration coefficient, k ₃ is a torsion coefficient, L ₁ , t ₁ , d ₁ , and G are the length, thickness, width, lateral elastic modulus, L ₂ , t ₂ , d ₂ , E represents the length, thickness, width, and longitudinal elastic modulus of the second torsion bar, and M, a, and b represent the weight, vertical length, and horizontal length of the mirror, respectively. Here, the length of the torsion bar is the length in the longitudinal direction of the torsion bar when FIG. 9 is viewed in the direction of the paper, and the width is the shorter length. The thickness of the torsion bar is the length of the torsion bar in the paper surface direction.

Next, a calculation formula for the force F required to apply to the second torsion bar and the displacement amount ΔL (see FIG. 11) of the second torsion bar to tilt the mirror portion 24 by a predetermined angle, and on the second torsion bar The calculation formula of the generated force F _A and the displacement amount ΔL _A of the piezoelectric film 28 arranged in FIG. Here, in order to facilitate the calculation, the force generated in the direction of the beam 25 by the piezoelectric film 28 as shown in FIG. 11 is an equally distributed load on the second torsion bar in the entire area where the piezoelectric film 28 is disposed. It is assumed that a load is applied, and it is assumed that a displacement amount and a generated force of 10 times can be obtained by using resonance. Incidentally, since it is necessary to be able to tilt a predetermined angle mirror 24 by driving the piezoelectric film 28, it is necessary to satisfy _{F <F A, ΔL <ΔL} A.

Here, θ is the rotation angle of the mirror section 24, I is the second moment of section of the second torsion bar, L _a , t _a , d _a , d ₃₁ , S _11E , and V are the length and thickness of the piezoelectric film 28, respectively. , Width, piezoelectric strain constant, and voltage applied to the piezoelectric film 28. The length of the piezoelectric film 28 is the length in the vertical direction in FIG. 9, and the width is the length in the left-right direction.

  The maximum load portion generated when the mirror portion 24 is tilted by a predetermined angle is a twisted portion (a portion indicated by a circle I in FIG. 9) of the first torsion bar. The maximum torsional stress (shear stress) τmax applied to this part is calculated by the following equation.

Here, k ₁ represents a torsion coefficient. For example, when the calculation is performed by substituting the input values shown in FIG. 12 into the equations 1 to 8, the resonance frequency fn is 68.3 kHz, and the displacement amount ΔL necessary to tilt the mirror unit 24 by, for example, 12.5 ° is 10.7 μm, the required force F is calculated to be 28.9 mN. Further, the displacement amount [Delta] L _A piezoelectric film 28 generates the 2.63 mm, the generated force F _A satisfies the 43.3mN _{next, F <F A, ΔL <} ΔL A.

  Further, the maximum torsional stress τmax loaded on the first torsion bar is 371 MPa. In this respect, since the fracture strength of silicon, which is a material of the torsion bar, is about 2 GPa, it can be said that the durability is sufficient. From the above calculation results, it can be said that the drive mirror 22 of the present embodiment is a drive mirror having an excellent configuration that can satisfy high-level requirements for the scanning speed and the mirror scanning angle and also has durability.

  Next, the configuration of Patent Document 4 will be described using FIG. 10 for comparison. First, the operation of the drive mirror having the configuration of Patent Document 4 will be briefly described. In this configuration, the mirror unit 24 is vibrated by a method in which the bending deformation of the torsion bar existing on the left and right sides of the mirror unit 24 is converted into the torsional deformation. The description will focus on only one side of the torsion bar. A piezoelectric film 28 is laminated on each side of the pair of first torsion bars (the front side in FIG. 10). When a voltage is applied to each piezoelectric film 28, the piezoelectric film 28 is piezoelectric. The film 28 expands and contracts, and the first torsion bar is bent and deformed. And since the voltage applied to each piezoelectric film 28 is set so that the piezoelectric film 28 disposed in each of the pair of first torsion bars alternately expands and contracts, the second and third torsion bars The mirror portion 24 connected to the first torsion bar vibrates via the vibration.

  Even in such a configuration, the resonance frequency fn and the moment of inertia J of the mirror portion 24 are the same as those in Equations 1 and 3, respectively. However, since the spring stiffness k is only the bending stiffness of the first torsion bar, the spring stiffness k is expressed by the following equation.

  About others, it calculates | requires similarly to the case of this embodiment. In the case of the configuration of Patent Document 4, the maximum load portion generated when the mirror portion 24 is tilted by a predetermined angle is the portion indicated by the circle K in FIG. 10 of the first torsion bar, and the sum of the torsional stress and the bending stress. Value. In this respect, the drive mirror 22 of the present embodiment is different from that the torsional stress (circle I part in FIG. 10) and the bending stress (circle J part in FIG. 10) work at different positions.

  As a result of calculating the configuration of Patent Document 4, a solution that satisfies the scanning speed, scanning angle, and durability of the mirror unit 24 at a high level as in the present embodiment cannot be obtained, and the scanning speed can be obtained only up to about 10 kHz. As a result. The difference between the two can be attributed to the following points.

  In the drive mirror 22 of the present embodiment, the spring rigidity related to the scanning speed of the mirror unit 24 is obtained by adding the torsional rigidity of the first torsion bar and the bending rigidity of the second torsion bar. On the other hand, in the case of the configuration shown in Patent Document 4, the spring rigidity is obtained only by the bending rigidity of the first torsion bar. For this reason, unlike the case of Patent Document 4, the drive mirror 22 of the present embodiment can increase the scanning speed while distributing the load applied to the torsion bar. Therefore, the drive mirror 22 of this embodiment is more advantageous in terms of durability than the drive mirror of Patent Document 4.

  In the drive mirror 22 of the present embodiment, the second torsion bar on which the piezoelectric film 28 is disposed is configured to sandwich the first and third torsion bars from the side. On the other hand, in the configuration disclosed in Patent Document 4, the first torsion bar on which the piezoelectric film 28 is disposed is disposed on the same plane as the second and third torsion bars.

  For this reason, in the case of Patent Document 4, if the width of the first torsion bar is increased in order to increase both the rigidity of the spring and the scanning speed, the length of the second torsion bar needs to be increased. It is necessary to increase the amount of displacement of the bar, and conversely, the load on the first torsion bar increases. On the other hand, in the case of the drive mirror 22 of the present embodiment, even if the width of the first torsion bar is increased in order to ensure durability, the amount by which the second torsion bar is displaced to rotate the mirror portion 24 is changed. Therefore, it is possible to increase the scanning speed while ensuring durability. Therefore, also in this respect, the drive mirror 22 of this embodiment is more advantageous in terms of durability than the drive mirror of Patent Document 4.

  The drive mirror 22 of the present embodiment has been described above, but the configuration of the drive mirror is not limited to the configuration of the present embodiment, and can be modified without departing from the object of the present invention. For example, the number of beams 25 may be two or more, and the position of the piezoelectric film 28 disposed on the drive arms 29a and 29b (see FIG. 6) may be provided on the side where the beams 25 are present. Further, the drive arms 29a and 29b and the mirror part 24 do not necessarily have to be provided in parallel. For example, the configuration shown in FIG. 6B may be configured to be rotated by 45 ° in the clockwise direction. However, in this case, a fixing portion for fixing the end portions of the drive arms 29a and 29b is separately required.

  Further, the number of drive arms 29a and 29b is not limited to two, and may be one or more than three, and the configuration of the drive arms 29a and 29b is, for example, a configuration as shown in FIGS. It does not matter. FIG. 13A is a schematic view showing a modified example of the configuration of the drive mirror 22, and FIG. 13B is a view of a cross section AA ′ of FIG. FIG.13 (c) is the figure which looked at cross-section BB 'of Fig.13 (a) from the left direction of the figure.

  In the configuration shown in FIG. 13, unlike the case of the drive arm 29 a in the drive mirror 22 of the present embodiment, the arm portions 27 a and 27 b of the drive arm 29 a are provided in line symmetry with respect to the beam 25. This also applies to the drive arm 29b. In this configuration, when the mirror portion 24 is rotated, unlike the case of the drive mirror 22 shown in the present embodiment, voltages of opposite poles are applied between the arm portions 27a and 27c and the arm portions 27b and 27d. Different in need.

  The details of the configuration of the drive mirror 22 constituting the optical scanning unit 9 have been described above. Next, the details of the configuration of the overall drive device 23 constituting the optical scanning unit 9 will be described. FIG. 14 is a schematic front view showing the configuration of the overall drive device 23.

  The entire drive unit 23 includes a rotation shaft 31 for rotating the entire drive mirror 22, a bearing 32 for the rotation shaft 31, and a rotation drive unit 33 for rotating the rotation shaft 31. The rotation driving unit 33 includes a base 34, a first piezoelectric element 35, a second piezoelectric element 36, and a chip unit 37 that connects the first piezoelectric element 35 and the second piezoelectric element 36. Is done.

  The first and second piezoelectric elements 35 and 36 are fixed to the base 34 with an adhesive or the like. The first piezoelectric element 35 and the second piezoelectric element 36 are fixed with an angle of approximately 90 °. The top portion of the tip portion 37 that connects the first and second piezoelectric elements 34 and 35 is formed of a rigid body so as to be pressed against the rotation shaft 31. In the present embodiment, the first piezoelectric element 35 and the second piezoelectric element 36 are fixed at an angle of 90 °, but the present invention is not limited to this.

  A voltage having a phase difference of 90 ° as shown by a solid line and a dotted line in FIG. 15, for example, is applied to the first piezoelectric element 35 and the second piezoelectric element 36 by a control circuit (not shown). It has become. For this reason, the first and second piezoelectric elements 35 and 36 perform stretching vibration with a phase difference of 90 °, whereby the tip portion 37 performs elliptical motion in the P direction, for example, as shown in FIG.

  In the present embodiment, the tip portion 37 is set so as to be pressed against the rotating shaft 31 only when the arrow portion shown in the elliptical orbit in FIG. 16 moves, for example. For this reason, the rotating shaft 31 rotates only when the tip portion 37 is pressed against the rotating shaft 31, and the rotation stops when the tip portion 37 moves away from the rotating shaft 31. That is, the drive of the rotating shaft 31 is set to be step driven.

  In addition, in the whole drive device 23 of this embodiment, although it has set it as the structure which drives the drive part 33 with a piezoelectric element, it is not the meaning limited to this. For example, a magnetostrictive element or other electrical / mechanical energy conversion element may be used instead of the piezoelectric element. Further, a configuration may be adopted in which a gear is provided on the rotating shaft 31 and the rotating shaft 31 is driven by a stepping motor.

  The configuration of the drive mirror 22 and the entire drive device 23 that constitute the optical scanning unit 9 has been described above, and the light scanning method of the optical scanning unit 9 will be described. Light scanning by the optical scanning unit 9 is controlled by an optical scanning control unit 14 (see FIG. 1). Then, the light scanning control unit 14 determines the driving mirror 22 and the overall driving device 23 based on a signal from the light control unit 2 (see FIG. 1) and a signal from a mirror position detection unit 13 (see FIG. 1) described later. Perform motion control.

  As described above, in the image display device 1 according to the present embodiment, the light scanning in the light scanning unit 9 causes the display unit 15 (see FIG. 1) to perform the horizontal light scanning to drive the drive mirror 22. Accordingly, the optical scanning in the vertical direction is performed by driving the entire driving device 23.

  In the present embodiment, in order to increase the vertical resolution, the horizontal light scanning speed Vx is set to be considerably higher than the vertical light scanning speed Vy. The speed difference preferably satisfies Vx / Vy> 500, and more preferably satisfies Vx / Vy> 1000. Thereby, VGA image quality (vertical resolution of 480 lines) and HDTV image quality (vertical resolution of 1080 lines) can be achieved.

  The vertical scanning frequency is set to be higher than 50 Hz. Thereby, the display cycle of the display unit 15 is shortened, and the motion of the moving image can be smoothed.

  FIG. 17 is a schematic diagram showing how light is scanned on the display unit 15 such as a screen by the light scanning unit 9. In the present embodiment, the optical scanning is set from the upper left of the display unit 15. The optical scanning start position (the portion indicated by the circle S in the figure) is arranged outside the display unit 15.

  When the optical scanning starts, the light is first scanned horizontally in the right direction in the figure by the vibration of the mirror unit 24 by the drive mirror 22. Then, when the light goes out of the display unit 15, the entire drive device 23 drives the rotary shaft 31 (see FIG. 5) stepwise, and the light is scanned downward in the figure. At this time, since the driving of the mirror unit 24 by the driving mirror 22 continues, the mirror unit 24 is driven by both the driving mirror 22 and the overall driving device 23, for example, as shown by a circle T in the figure. Optical scanning is performed in a manner that draws an arc.

  Note that the setting of the rotation amount of the rotary shaft 31 by the overall drive device 23 at this time is such that the predetermined rotation amount to be scanned in the vertical direction is rotated only by rotating the rotary shaft 31 once. However, it is preferable to set such that a predetermined amount of rotation is reached by rotating the rotating shaft 31 several times in small increments.

  That is, in the case of the overall drive device 23 having the configuration of the present embodiment, the rotation amount of the rotation shaft 31 by the elliptical rotation of the chip portion 37 (see FIG. 14) is A, and the image is moved by one pixel in the vertical direction. B / A> 3, more preferably B / A> 10, where B is the amount of rotation of the rotary shaft 31 required for the above. With this configuration, even when an error occurs in the rotation amount of the rotary shaft 31 due to one elliptical rotation of the tip portion 37, the drive of the overall drive device 23 is controlled so as to correct the error. Thus, the error can be corrected while rotating a predetermined rotation amount (for example, one pixel of the image).

  When the mirror unit 24 is rotated by a predetermined amount of rotation by the overall driving device 23 and light is scanned downward in the figure, this time, the light is scanned horizontally toward the left in the figure only by the driving mirror 22, When the light goes out of the display unit 15, the whole driving device 23 is driven and the light is scanned in the downward direction as before. The above is repeated to a predetermined position below the display unit 15. Then, when the optical scanning is performed up to a predetermined position (portion indicated by a circle U in the figure), the whole drive device 23 rotates the rotating shaft 31 (see FIG. 5) in the opposite direction to the above, and the light is increased. Scan in the direction.

  FIG. 18 is an explanatory diagram for explaining optical scanning when light scanned from the top to the bottom on the display unit 15 by the optical scanning unit 9 is scanned from the bottom to the top. The solid line in the figure indicates the light scanning position (same as in FIG. 17) when the light is scanned from the top to the bottom by the light scanning unit 9, and the chain line in the figure indicates that the light is from bottom to top. It shows the scanning position of light when it is scanned.

  When the light is scanned to a predetermined position below the display unit 15 (a position indicated by a circle U in FIG. 17), the entire drive device 23 rotates the rotating shaft 31 in the reverse direction, and the light is directed from the top to the bottom. Rotate the rotation shaft 31 by half the amount of rotation when it was scanned in order to shift the light upward. The light shifted upward is scanned horizontally toward the left in the figure, and when it goes out of the display unit 15, the entire drive device 23 performs step driving to scan the light upward. At this time, the rotation amount by which the entire drive device 23 rotates the rotation shaft 31 is rotated by the same predetermined rotation amount as when light is scanned from top to bottom. By repeating this scanning, the light is scanned on the dotted line position in FIG. 18, and the light is scanned to a predetermined position above the display unit 15.

  The light scanning method by the light scanning unit 9 is not limited to the above scanning method. For example, the display unit 15 may be scanned from the top to the bottom and then scanned from the bottom to the top so as to pass through the same position. However, as in the present embodiment, after scanning light from the top to the bottom of the display unit 15, it is better to perform light scanning so that the light scanned from the bottom to the top passes between the time of scanning from the top to the bottom. Easy to get high resolution images.

  In the present embodiment, the whole driving device 23 is step-driven when the light to be scanned in the horizontal direction goes out of the display unit 15, but the present invention is not necessarily limited thereto. In other words, in the present embodiment, a part of both ends of the horizontal area scanned by the drive mirror 22 is not used as an image area, but the entire horizontal area scanned by the drive mirror is not used. It may be configured such that the driving timing of the overall driving device 23 is set when the light reaches the end of the display unit 15 so that it can be used as an image.

  Further, the entire drive device 23 may be driven at a constant speed instead of step drive. However, in this case, since the light is scanned in the vertical direction simultaneously with the light scanning in the horizontal direction by the drive mirror 22, image defects may occur at both ends of the display unit 15. Is preferably step driven and driven at both ends in the horizontal direction.

  Although the light scanning method by the light scanning unit 9 has been described above, in order to form an image on the display unit 15, the light scanning position by the light scanning unit 9 and the emission from the light sources 4 to 6 to form the image. It is necessary that the intensity of the emitted laser beam corresponds. For this reason, in the optical scanning optical device 3, the mirror position detection light source 12 (see FIG. 1) and the mirror position detecting means 13 are provided so that the position of the mirror portion 24 (see FIG. 6) of the drive mirror 22 can be grasped. (See FIG. 1).

  The mirror position detection light source 12 irradiates light to the back side of the optical scanning surface of the mirror unit 24, and the mirror position detection means 13 is configured to receive this reflected light. Then, the mirror position can be detected from the information regarding the light receiving position of the reflected light. Information regarding the light receiving position detected by the mirror position detecting means 13 is supplied as a signal to the light control unit 2, and the light control unit 2 controls the operations of the light sources 4 to 6 based on this information. Information about the light receiving position detected by the mirror position detection means 13 is also supplied to the optical scanning control unit 14 (see FIG. 1), and the optical scanning control unit 14 thereby uses the driving mirror 22 and the entire driving device 23. The drive is controlled.

  The means for detecting the position of the mirror unit 24 is not limited to the above-described configuration, and can be modified without departing from the object of the present invention. That is, for example, a configuration in which detection means is provided so that it can be determined only whether or not the mirror portion 24 is positioned so as to reflect light at the optical scanning start position (the position of the circle S in the figure) in FIG. It doesn't matter.

  Next, the projection optical system 10 (see FIG. 1) will be described. The projection optical system 10 of this embodiment has a role of eliminating image distortion in addition to forming an image of the laser beam scanned by the light scanning unit 9 on the display unit 15. In the image display device of the present embodiment, the light scanning method of the optical scanning unit 9 is the resonance driving method by the driving mirror 22 in the horizontal direction, the step driving method by the whole driving device 23 in the vertical direction, and the horizontal and vertical directions. Is different. For this reason, when the laser beam from the optical scanning unit 9 is imaged using a normal axisymmetric lens, for example, as shown in FIG. 19, the image is distorted asymmetrically. Note that FIG. 19 is an image diagram and does not necessarily show an actual state of distortion.

  For this reason, the projection optical system 10 of the present embodiment uses an anamorphic aspherical lens manufactured in a shape having different curvatures in the horizontal direction and the vertical direction, thereby eliminating the asymmetric distortion of the image. When this anamorphic aspherical lens is used, the horizontal and vertical projection methods of laser light reflected by the mirror section 24 of the optical scanning unit 9 and incident on the anamorphic aspherical lens are different. The anamorphic aspherical lens may be made of glass or plastic made by plastic molding. Plastic molding is particularly advantageous in terms of cost.

  First, the horizontal projection method will be described with reference to FIG. FIG. 20 is a schematic diagram for explaining how the light reflected by the mirror unit 24 forms an image on the display unit 15 via the projection optical system 10, and is a view of the display unit 15 viewed from directly above. . A chain line in the figure indicates an optical axis 39 that is a center line of a light beam toward the center 38 of the display unit 15. Further, the solid line and the alternate long and short dash line depict the center line of the light beam that is reflected by the mirror unit 24 and guided to the display unit 15 in two states in which the mirror unit 24 rotates counterclockwise in the drawing. The projection optical system 10 is drawn simply for convenience.

  Since the scanning method of the light in the horizontal direction is resonance driving, the scanning speed is maximum on the central side (the center 38 side in the figure) of the display unit 15 among the light scanned in the horizontal direction, and from the central side to the end. The scanning speed of light becomes slower. For this reason, it is necessary to adopt a projection method in which the width is narrowed on the center side in the horizontal direction and the width is widened on the end side. Therefore, the projection method in the horizontal direction of the anamorphic aspheric lens of the present embodiment is a method represented by the following equation.

yh = a · arcsin (k · θ / θmax)
Here, θ is a projection of incident light reflected from the mirror section 24 and incident on the projection optical system 10 onto a plane that includes the optical axis 39 and is parallel to the horizontal direction of the display section 15 (corresponding to a paper plane in the figure). This is the angle (in radians) that the projected light sometimes makes with the optical axis 39. Further, θmax is the maximum value that θ can take, and corresponds to twice the angle at which the mirror portion 24 is tilted to the maximum. yh represents the height of the image in the horizontal direction, and incident light incident on the projection optical system 10 is projected onto the display unit 15 at an angle with a line in the vertical direction (paper direction in the drawing) passing through the center 38 of the display unit 15. This corresponds to the distance (unit: mm) from the image formed when the image is formed. a and k are predetermined coefficients. The coefficient k is a coefficient determined by the ratio of not displaying an image in the entire horizontal area scanned by the drive mirror 22.

  Next, a vertical projection method will be described with reference to FIG. FIG. 21 is a schematic diagram for explaining a state in which the light reflected by the mirror unit 24 forms an image on the display unit 15 through the projection optical system 10, and is a diagram of the display unit 15 viewed from the side. A chain line in the figure indicates an optical axis 39 that is a center line of a light beam toward the center 38 of the display unit 15. A solid line and an alternate long and short dash line depict a center line of a light beam reflected by the mirror unit 24 and guided to the display unit 15 in two states in which the mirror unit 24 rotates counterclockwise in the drawing. The projection optical system 10 is drawn simply for convenience.

  Since the light scanning method in the vertical direction is step driving, the image in the vertical direction is not distorted due to the difference in light scanning speed as in the horizontal direction. Projection may be performed by a method in which the height of the image is determined according to the incident angle. For this reason, the projection method in the horizontal direction of the anamorphic aspheric lens of the present embodiment is a method represented by the following equation.

yv = f · φ
Here, f is the focal length (unit: mm) of the projection optical system 10. φ is projected when the incident light reflected from the mirror unit 24 and incident on the projection optical system 10 is projected onto a plane that includes the optical axis 39 and is parallel to the vertical direction of the display unit 15 (corresponding to a paper surface in the figure). The angle (in radians) that light makes with the optical axis. yh represents the height of the image in the vertical direction, and incident light incident on the projection optical system 10 is projected onto the display unit 15 at an angle with a line in the horizontal direction (paper direction in the drawing) passing through the center 38 of the display unit 15. This corresponds to the distance (unit: mm) from the image formed when the image is formed.

  As described above, if an anamorphic aspheric lens is used in the projection optical system 10, asymmetric distortion of an image can be eliminated. However, the lens that eliminates the asymmetric distortion is not limited to an anamorphic aspheric lens. For example, two cylinder lenses arranged orthogonally may be combined to perform the same function as an anamorphic aspheric lens.

  In the projection optical system 10 of the present embodiment, two lenses are arranged. However, the present invention is not limited to this and can be changed without departing from the object of the present invention. The anamorphic aspherical lens used in the projection optical system 10 of the present embodiment includes an optical system including a two-dimensional optical scanning device in which the horizontal scanning method is driven by vibration and the vertical scanning method is step driving. For example, in the image display device 1, the drive mirror 22 can be applied to an electromagnetic drive type or an electrostatic drive type.

  As described above, in the image display apparatus 1 according to the present embodiment, image distortion due to the horizontal light scanning method being resonant drive occurs, and thus the projection optical system 10 has an anamorphic aspheric lens. However, it is possible to eliminate the asymmetric distortion of the image without necessarily using such a configuration.

  That is, in the case of the resonance driving method, the horizontal scanning speed of the display unit 15 is fast on the center side and slow on the end side, so the on / off switching speed of the laser light emitted from the light sources 4 to 6 is set to the display unit. It is also possible to eliminate distortion by adopting a configuration in which the light control unit 2 (see FIG. 1) is controlled so as to be faster at the horizontal center side of 15 and slower toward the end side. Note that. The on / off switching speed of the laser light from the light sources 4 to 6 can be controlled by controlling the frequency modulation of the light sources 4 to 6 in the light source frequency modulation unit 19 (see FIG. 3). Switching light on and off is faster, and vice versa if the frequency is lowered. It is also possible to adopt a configuration in which such a configuration is combined with a configuration using an anamorphic aspheric lens in the projection optical system.

  In the above description, elimination of image distortion caused by different optical scanning driving methods in the horizontal direction and the vertical direction has been described. However, as in the present embodiment, the mirror unit 24 that performs optical scanning is used. When the incident light has a non-zero finite angle, the display image (grid) displayed on the display unit 15 is, for example, the central part of the horizontal line among the four lines constituting the frame of the image. May generate trapezoidal distortion that curves downward.

  For this reason, the projection optical system 10 may be additionally decentered parallel and / or tilted to correct distortion. In the present embodiment, an anamorphic aspheric lens is used for the projection optical system 10, but a lens (optical system) using a free-form surface may be used instead. In this way, it is possible to eliminate image distortion caused by different optical scanning driving methods and the above-mentioned trapezoidal distortion.

  Further, with the projection optical system 10 alone, distortion of the image displayed on the display unit 15 (here, all distortions derived from the apparatus configuration in the optical scanning optical device 3 including the above-described two distortions). If the light control unit 2 cannot sufficiently solve the problem, for example, the light control unit 2 may control the on / off timing of the light sources 4 to 6 to be different from the original timing, thereby correcting the distortion. This will be described with reference to FIG. FIG. 22 is a schematic diagram for explaining a method of correcting image distortion by the light control unit 2.

  Originally, the light control unit 2 controls the emission of the laser light from the light sources 4 to 6 so that images are sequentially drawn on horizontal dots (for example, 41a to 41d in the figure). However, when the horizontal line of the image is distorted as shown in FIG. 22, the laser light from the light sources 4 to 6 is not emitted so as to draw an image sequentially from the dots 41a to 41d. If the light control unit 2 controls the on / off timing of the laser light emitted from the light sources 4 to 6 so as to draw images to be drawn on 41b and 41c at 40a and 40b, the image displayed on the display unit 15 is Apparently not distorted. Therefore, if the light control unit 2 is configured so that such control can be appropriately performed, it is possible to obtain an image with extremely little image distortion.

  Further, the image projected by the image display device 1 includes a trapezoidal distortion that occurs when the display unit 15 such as a screen is tilted, in addition to the distortion derived from the configuration of the image display apparatus 1 main body. For this reason, the light control unit 2 may be configured so that the trapezoidal distortion can be corrected by the light control unit 2.

  The image display device including the drive mirror and the optical scanning optical device according to the present invention has been described above. However, the drive mirror and the optical scanning optical device according to the present invention can be applied to devices other than the image display device. For example, as shown in FIG. 23, it can also be mounted on a laser beam printer (LBP) or the like.

  FIG. 23 shows the relationship between an optical scanning optical device having a drive mirror of the present invention mounted on an LBP and a photosensitive drum. In the figure, 100 is an optical scanning optical device of the present invention, 101 is a laser light source, 102 is a cylindrical lens, 103 is a driving mirror of the present invention, 104 is an fθ lens, and 105 is a photosensitive drum.

  The laser light emitted from the laser light source 101 passes through the cylindrical lens 102, is reflected by the drive mirror 103, passes through the fθ lens 104, and forms an image on the photosensitive drum 105. The drive mirror 103 is configured as shown in FIG. 6, for example, and is rotated in the longitudinal direction of the photosensitive drum 105 by rotating the mirror unit 24 (depicted on the photosensitive drum 105 in the drawing). It is set so that the laser beam can be scanned in the direction of the arrow.

  In such an apparatus, conventionally, when producing an LBP corresponding to high speed, it is necessary to arrange a plurality of polygon mirrors for performing optical scanning, so that the apparatus is enlarged. However, since the driving mirror 103 of the present invention rotates the mirror section 24 at high speed and can perform optical scanning at high speed, if one driving mirror 103 is disposed, an LBP corresponding to high speed can be manufactured. For this reason, the whole apparatus is not increased in size and power consumption can be reduced.

  Examples of projectors that are image display apparatuses according to the present invention will be described below.

  The screen size was 20 inches and the projection distance was 300 mm. The projection angle of the optical system was ± 37 degrees in the horizontal direction and ± 22 degrees in the vertical direction. The screen resolution was a display resolution of 1920 × 1080 size, which is equivalent to that of a high-definition television. The projector optical system has the configuration shown in FIG. 1, and the projection optical system uses an anamorphic aspherical lens having different projection methods in the horizontal and vertical directions shown in the present embodiment.

  Red, green, and blue laser diodes were used as light sources, the red wavelength was 660 nm, the green wavelength was 532 nm, and the blue wavelength was 450 nm. The modulation frequency of the laser diode was 125 MHz.

  The driving mirror shown in FIG. 6 is used as the driving mirror. In FIG. 6A, the entire size of the driving mirror is 17.4 mm in the horizontal direction and 5 mm in the vertical direction. The size of each part of the driving mirror is as follows. The size shown in FIG. Further, the whole drive device having the structure shown in FIG. 14 was used, and the diameter of the rotating shaft was set to φ10 mm. The scanning frequency of light in the horizontal direction by the driving mirror was 65000 Hz, and the scanning frequency of light in the vertical direction by the whole driving device was 60 Hz.

  In this projector, the power consumption of the laser diode as the light source is about 2.5 W, including the three colors of red, green, and blue. The power consumption of the drive mirror and the entire drive device were both about 0.5 W. The power consumption of the control system was about 1.5W. Therefore, the overall projector was 5 W.

  However, since no safety countermeasure parts or the like are provided for the control system, a larger value will be obtained if these are provided. Even in this case, since the power consumption of the entire projector does not exceed 10 W, the result is that the battery can be driven.

  According to the drive mirror of the present invention, the beam having the mirror is driven in a piezoelectric manner, and the beam is rotated in a style that rotates the cone from the side. For this reason, the mirror can be rotated at a high speed and a wide angle, and it has sufficiently high durability even when used under such conditions. Therefore, it can be applied to an image display device such as a projector or a high-speed LBP that needs to perform optical scanning at high speed.

  The optical scanning optical device of the present invention has a configuration including a driving mirror that can rotate the mirror at high speed and an entire driving device that rotates the entire driving mirror by step driving, so that there is a large difference in the scanning speed of light scanning in two directions. be able to. For this reason, it becomes possible to provide a high-resolution projector or the like. Further, since the rotation axis of the mirror of the drive mirror and the rotation axis of the mirror of the entire drive device are orthogonal to each other so as to pass through the center of the reflection surface of the mirror, a pupil can be arranged near the reflection surface. The image display device including the optical scanning optical device can be reduced in size.

  In addition, the optical scanning optical device of the present invention is a method of scanning light in two directions using different driving methods. However, it is a special projection optical system, and projection in two directions according to the difference in driving methods. Since the methods are set differently, it is possible to provide an image with high resolution without performing complicated electrical control when applied to an image display device.

  Since the image display device of the present invention includes the drive mirror and the optical scanning optical device, the image display device has high resolution, the entire device is small, and further has low power consumption. Therefore, it is possible to provide a portable image display device.

These are block diagrams which show schematic structure of the image display apparatus of this embodiment. These are the schematic perspective views which show the general view of the optical scanning optical apparatus with which the image display apparatus of this embodiment is provided. These are block diagrams which show the structure of the light control part with which the image display apparatus of this embodiment is provided. These are explanatory drawings which show an example when not using a color synthesis prism. These are the schematic perspective views which show the optical scanning part with which the image display apparatus of this embodiment is provided. These are explanatory drawings for demonstrating the structure of the drive mirror of this embodiment. These are explanatory drawing for demonstrating the manufacturing method of the drive mirror of this embodiment. These are the schematic diagrams for demonstrating operation | movement of the drive mirror of this embodiment. These are explanatory drawings explaining the structure of the drive mirror used for the calculation in order to perform the calculation for showing the performance superiority of the drive mirror of this embodiment. These are the schematic diagrams which show the structure of the optical scanning device of patent document 4 used for the comparison in order to show the performance advantage of the drive mirror of this embodiment. These are the figures which showed the calculation model of the generated force of the piezoelectric film used when calculating the performance advantage of the drive mirror of this embodiment. These are tables showing the numerical values used to calculate the performance advantage of the drive mirror of this embodiment. These are explanatory drawings which show the modification of the structure of the drive mirror of this embodiment. These are the schematic front views which show the structure of the whole drive device of this embodiment. These are the figures which showed the pattern of the voltage applied to the piezoelectric element provided on the whole drive device of this embodiment. These are the schematic diagrams for demonstrating the elliptical motion of the chip | tip part of the whole drive device of this embodiment. These are the schematic diagrams which showed a mode that light scanned on a display part by the optical scanning part in the image display apparatus of this embodiment. These are explanatory drawings explaining the scanning method when light is scanned on the display unit by the optical scanning unit in the image display apparatus of the present embodiment. FIG. 4 is an image diagram showing a state where an image is distorted. These are schematic diagrams for explaining how the light reflected by the mirror unit forms an image on the display unit through the projection optical system in the image display device of the present embodiment, and is a diagram of the display unit viewed from directly above. is there. These are schematic diagrams for explaining how the light reflected by the mirror unit forms an image on the display unit through the projection optical system in the image display device of the present embodiment, and is a diagram of the display unit viewed from the side. . These are the schematic diagrams for demonstrating the correction method of the distortion of the image by a light control part. These are the schematic diagrams which show the partial structure of LBP provided with the drive mirror and optical scanning optical apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image display apparatus 2 Light control part 3 Optical scanning optical apparatus 4-6 Light source 7 Color synthesis prism 8 Collimator lens 9 Optical scanning part 10 Projection optical system 15 Display part 16 Image signal input part 17 Luminance signal conversion part 18 Light source luminance control part DESCRIPTION OF SYMBOLS 19 Light source frequency conversion part 22 Drive mirror 23 Whole drive device 24 Mirror part 24a Reflective layer 25 Beam 26 Fixed frame (fixed part)
27a to 27d Arm portion 28 Piezoelectric film 29a, 29b Driving arm 31 Rotating shaft 32 Bearing 33 Rotating driving portion 34 Base 35 First piezoelectric element (first displacement portion)
36 2nd piezoelectric element (2nd displacement part)
37 Chip part 38 Center of display part 39 Optical axis

Claims (22)

In a drive mirror comprising: a mirror portion provided with a reflecting surface for reflecting light; a beam that holds the mirror portion; a fixing portion that fixes the beam; and a drive portion that rotates the beam by expansion and contraction of a piezoelectric element. ,
The drive unit has at least one drive arm composed of two arms connected to the beam so as to sandwich the beam, and the arm is disposed substantially perpendicular to the beam, The drive mirror is provided with the piezoelectric element.   2. The drive mirror according to claim 1, wherein the piezoelectric element is provided on a back surface side on a side where the arm portion sandwiches the beam.   The drive mirror according to claim 1, wherein the arm portion is provided substantially in parallel with the reflection surface.   The drive mirror according to any one of claims 1 to 3, wherein the two arm portions are provided substantially in point symmetry with respect to a cross-sectional center of the beam.   5. The drive mirror according to claim 1, wherein the drive unit includes two drive arms, and the drive arms are provided symmetrically with respect to the mirror unit.   The drive mirror according to claim 1, wherein the fixed part is disposed so as to surround the mirror part, and one end of the arm part is connected to the fixed part.   The drive mirror according to claim 1, wherein the mirror unit is provided to vibrate by resonance.   An optical scanning optical apparatus comprising the drive mirror according to claim 1. The light is two-dimensionally driven by driving a light source, a collimating optical system that converts the light emitted from the light source into parallel light, and a mirror unit provided with a reflecting surface that reflects the light that has passed through the collimating optical system. In an optical scanning optical apparatus comprising: an optical scanning unit that scans; and a projection optical system that guides light scanned by the optical scanning unit to a display unit.
The two-dimensional optical scanning of the optical scanning unit is performed by rotating the mirror unit around two rotation axes that pass through the approximate center of the reflective surface and are parallel to the reflective surface and orthogonal to each other. One of the rotational driving by the rotation shaft is performed by a driving mirror having the mirror portion and capable of optical scanning in one dimension, and the other is performed by using an entire driving device that integrally rotates the entire driving mirror. An optical scanning optical device.   The optical scanning optical apparatus according to claim 9, wherein the driving mirror is the driving mirror according to claim 1.   The optical scanning optical apparatus according to claim 9, wherein the entire driving device is step-driven.   The overall drive device includes the drive mirror, a rotary shaft coupled to the drive mirror and capable of rotating the drive mirror, a bearing of the rotary shaft, and a rotary drive unit that rotationally drives the rotary shaft. The rotation drive unit is pressed against the rotation shaft while generating an elliptical rotation by connecting the first displacement unit and the second displacement unit fixed on the base and extending and vibrating with a predetermined phase difference and the two displacement units. The optical scanning optical device according to claim 11, further comprising a chip portion. When the chip unit makes one oval rotation, the rotation amount of the rotation shaft is A, the light is scanned by driving the whole driving device, and the image on the display unit is scanned by one pixel in the light scanning direction. The optical scanning optical apparatus according to claim 12, wherein the following expression (A) is satisfied, where B is an amount of rotation of the rotating shaft necessary for movement.
B / A> 3 (A)   14. The optical scanning optics according to claim 9, wherein the projection optical system is provided so that a projection method is different in each of two directions in which the optical scanning unit performs optical scanning. apparatus. In the projection method, the focal length of the projection optical system is f (mm), the central ray of the light beam toward the center of the display unit is the optical axis, and the incident light reflected by the mirror unit and incident on the projection optical system is , When projected onto a plane parallel to a first direction in which optical scanning is performed by the drive mirror among the two directions including the optical axis, an angle formed by the projected light and the optical axis is θ (rad), θmax is the maximum value that can be taken by θ, and the incident light is projected when projected onto a plane that includes the optical axis and is parallel to a second direction that is different from the first direction and includes the two directions. Is an angle formed by the optical axis φ (rad), a straight line passing through the center of the display unit and orthogonal to the first direction on the display unit, and an image formed by projecting the incident light onto the display unit And the second direction passing through the center of the display unit, and y1 (mm) When the distance between the intersecting straight line and the image formed by projecting the incident light onto the display unit is y2 (mm) and a and k are predetermined coefficients, the first direction and the second direction The optical scanning optical apparatus according to claim 14, wherein the projection methods are expressed by the following expressions (B) and (C), respectively.
y1 = a · arcsin (k · θ / θmax) (B)
y2 = f · φ (C)   16. The optical scanning optical apparatus according to claim 14, wherein an anamorphic aspherical lens or a free-form surface lens is used for the projection optical system.   The optical scanning optical apparatus according to claim 9, wherein a color combining prism is disposed between the light source and the optical scanning unit.   An image display device comprising the drive mirror according to claim 1.   An image signal input unit that inputs an image signal, a luminance signal conversion unit that converts the image signal input to the image signal input unit into a luminance signal, and a light source based on the luminance signal converted by the luminance signal conversion unit The light control unit according to any one of claims 9 to 17, comprising: a light source luminance control unit that controls intensity; and a light source frequency modulation unit that modulates a frequency of light emitted from the light source. An optical device, and the optical scanning in the horizontal direction of the display unit uses the driving mirror, the optical scanning in the vertical direction of the display unit uses the overall driving device, and the scanning speed in the horizontal direction is in the vertical direction. An image display device characterized by being faster than a scanning speed. 20. The image display device according to claim 19, wherein Vx and Vy satisfy the following expression (D), where Vx is the horizontal scanning speed and Vy is the vertical scanning speed.
Vx / Vy> 500 (D)   21. The image display apparatus according to claim 19, wherein the vertical scanning frequency is higher than 50 Hz.   The said light source frequency modulation part modulates so that the frequency of the light radiate | emitted from the said light source may differ in the center side and the edge part side of the said horizontal direction of the said display part. An image display device according to any one of the above.

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