WO2018092873A1

WO2018092873A1 - Optical element driving method and optical device

Info

Publication number: WO2018092873A1
Application number: PCT/JP2017/041440
Authority: WO
Inventors: 橋村淳司; 山田範秀; 菅原和弘
Original assignee: コニカミノルタ株式会社
Priority date: 2016-11-17
Filing date: 2017-11-17
Publication date: 2018-05-24
Also published as: JPWO2018092873A1

Abstract

The present invention provides an optical element driving method that enables reduction of load on an actuator in a system including a lens to be driven. In this optical element driving method, a spring 75 is provided for moving at least one movable optical element constituting a projection optical system 13, etc., along an optical axis AX, the spring 75 acting, concomitantly with an actuator 74, on the movable optical element at least in a direction parallel to the moving direction of the movable optical element, and the actuator 74 is operated using the action of the spring 75. Here, the movable optical element represents, for example, a movable lens part 51.

Description

Optical element driving method and optical device

The present invention relates to an optical element driving method and an optical apparatus for moving a movable optical element of an optical system along an optical axis direction, and particularly to an optical element driving method and an optical apparatus for moving a movable optical element at high speed.

As an optical element driving method, a method of driving a lens by a vibration actuator that vibrates an elastic body using an electromechanical conversion element that expands by applying a voltage is known (Patent Document 1). Japanese Patent Application Laid-Open No. 2004-228561 describes that if the frequency of the drive voltage applied to the electromechanical transducer is a resonance frequency corresponding to the natural frequency of the elastic body, the vibration can be generated efficiently and continued. However, the structure that vibrates the elastic body as disclosed in Patent Document 1 cannot have a large amplitude. In addition, no consideration is given to reducing the load on the actuator in the system including the lens to be driven.

Further, as another optical element driving method, a method using an ultrasonic actuator for camera shake correction driving of a camera is known (Patent Document 2). Patent Document 2 describes that an ultrasonic actuator vibrates efficiently because it is driven in a predetermined resonance state. However, Patent Document 2 does not consider reduction of the actuator load in a system including a lens to be driven.

JP 2009-124793 A JP 2004-56878 A

The present invention has been made in view of the above-described background art, and an object thereof is to provide an optical element driving method and an optical apparatus that can reduce the load on an actuator in a system including a lens to be driven. .

In order to achieve at least one of the above-described objects, an optical element driving method reflecting one aspect of the present invention is an optical element that moves at least one movable optical element constituting an optical system along the optical axis direction. In the driving method, a spring acting on the movable optical element in at least a direction parallel to the moving direction of the movable optical element is provided along with the actuator, and the actuator is operated using the action of the spring. Here, the movable optical element means, for example, a movable lens.

In order to achieve at least one of the above objects, an optical apparatus reflecting one aspect of the present invention includes an optical system that forms a projection image and at least one movable optical element that forms the optical system in the optical axis direction. , A spring that acts on the movable optical element at least in a direction parallel to the driving direction of the movable optical element, and a drive control unit that operates the actuator while using the action of the spring.

FIG. 1A is a side cross-sectional view showing a state in which the image display device, which is the optical device of the first embodiment, is mounted on a vehicle body, and FIG. 1B is a front view from the vehicle interior that explains the appearance of the image display device. is there. It is an expanded side sectional view explaining the structure of the image display apparatus of FIG. 1A. It is a conceptual diagram explaining the structure of the projection optical system of the image display apparatus of FIG. 1A. 4A is a cross-sectional view illustrating image formation by the image display device, and FIG. 4B is a view illustrating an eyebox capable of observing a virtual image. FIG. 5A is a plan view for explaining a movable optical element and its driving device included in the projection optical system, and FIG. 5B is a front view of a movable lens and the like. 6A and 6B are plan views for explaining the operation of the movable lens by the driving device. It is a block diagram explaining the control system of the image display apparatus of FIG. 1A. It is a figure explaining the motion and drive method of a movable lens. It is a top view explaining the movable lens integrated in the image display apparatus of 2nd Embodiment, and its drive device.

[First Embodiment]
Hereinafter, an optical element driving method according to a first embodiment of the present invention and an optical device using the method will be described.

1A and 1B are a conceptual side sectional view and a front view illustrating an image display apparatus 100 that executes an optical element driving method according to an embodiment. The image display device 100 is an optical device mounted in the vehicle body 2 as a head-up display device, for example, and includes a drawing unit 10 and a display screen 20. The image display device (optical device) 100 displays image information displayed on a display element 11 (described later) in the drawing unit 10 as a virtual image for the driver UN through the display screen 20.

The drawing unit 10 of the image display device 100 is installed so as to be embedded in the dashboard 4 of the vehicle body 2 and emits display light HK corresponding to an image including driving-related information toward the display screen 20. The display screen 20 is a concave mirror having translucency, and is also called a combiner. The display screen 20 is erected on the dashboard 4 with the lower end supported, and reflects the display light HK from the drawing unit 10 toward the rear of the vehicle body 2. In this case, the display screen 20 is an independent type installed separately from the front window 8. The display light HK reflected by the display screen (combiner) 20 is guided to an eye box SY (see FIG. 4B) corresponding to the pupil HT of the driver UN sitting on the driver's seat 6 and its peripheral position. The driver UN can observe the display light HK reflected by the display screen 20, that is, the display image IM as a virtual image in front of the vehicle body 2. On the other hand, the driver UN can observe external light transmitted through the display screen 20, that is, a real object or a real image such as a front scene. As a result, the driver UN observes a display image (virtual image) IM including operation-related information and the like formed by reflection of the display light HK on the display screen 20 so as to overlap the external image behind the display screen 20. Can do.

As shown in FIGS. 2 and 3, the drawing unit 10 includes a drawing device 12 including a display element 11, a projection optical system 13, a lens driving system 70, a circuit portion 19, and a housing 14. The driving-related information presented to the driver UN by the drawing unit 10 is not limited to information related to the operating state of the vehicle body 2 such as speed, but relates to a driving environment that assists the driver UN such as a vehicle and a pedestrian existing in front of the vehicle body 2. Contains information.

Although the detailed description of the drawing device 12 is omitted, in addition to the display element 11, an LED (light emitting diode) that emits light for illuminating the display element 11, a laser or other light source, and light from the light source An illumination optical system and the like for equalization are provided. The display element 11 may be a reflective element such as DMD (Digital Mirror Device) or LCOS (Liquid crystal on silicon), or a transmissive element such as liquid crystal. In particular, when a DMD is used for the display element 11, images can be switched at high speed while maintaining brightness, which is advantageous for display.

The projection optical system 13 is a variable optical system that changes the projection distance and the projection magnification, and includes a first projection optical unit 30 that forms a first intermediate image corresponding to an image formed on the display element 11, and a first projection optical unit 30. And a second projection optical unit 40 that displays a virtual image by causing image light corresponding to the first intermediate image TI1 to enter the display screen 20. The projection optical system 13 desirably has at least one aspheric surface from the viewpoint of miniaturization while ensuring the optical performance of the optical system.

In the projection optical system 13, an intermediate screen mSC is disposed at a position where the first intermediate image TI1 is formed between the first projection optical unit 30 and the second projection optical unit 40. Since the first intermediate image TI1 does not move in the direction of the optical axis AX or the like, it is not necessary to move the intermediate screen mSC, and the depth position of the display image (virtual image) IM only by the action of the movable lens unit 51 as a movable optical element described later. And both the viewing angle and the eyebox can be increased. The intermediate screen mSC is a diffusion plate whose light distribution angle is controlled to a desired angle. For the diffusion plate, for example, ground glass, a lens diffusion plate, a microlens array, or the like is used. By providing a diffusion plate as the intermediate screen mSC, the light utilization efficiency of the optical system can be made relatively high while easily ensuring the viewing angle and the eyebox size.

As illustrated in FIG. 3, the first projection optical unit 30 includes a plurality of lenses or lens groups that project the image of the display element 11. In the illustrated example, the first projection optical unit 30 is composed of four lenses.

The second projection optical unit 40 includes a relay optical unit 50 that relays the first intermediate image TI1, and a third projection optical unit 60 that is disposed on the display screen 20 side with respect to the relay optical unit 50. The second projection optical unit 40 forms a second intermediate image TI2 between the relay optical unit 50 and the third projection optical unit 60. By configuring the second projection optical unit 40 with two optical systems of the relay optical unit 50 and the third projection optical unit 60, the entire magnification is distributed to the relay optical unit 50 and the third projection optical unit 60. Can do. As a result, the viewing angle and eye box size of the entire system can be increased while increasing the F value of the relay optical unit 50, and the enlargement of the relay optical unit 50 can be prevented while being easy to use. And optical performance such as astigmatism can be ensured.

The relay optical unit 50 is an enlargement projection system and has a plurality of lenses or lens groups. In the example illustrated in FIG. 3, the relay optical unit 50 includes seven lenses. The relay optical unit 50 includes a movable lens unit 51 as a movable optical element on the display screen 20 side among a plurality of lenses or lens groups. The focal length of the projection optical system 13 can be changed or changed by moving the movable lens unit (movable optical element) 51 in the direction of the optical axis AX using a lens driving system 70 described in detail later. The movable lens unit 51 includes three or less lenses. Thereby, since the number of lenses constituting the movable lens unit 51 can be reduced, the load on the actuator 74 is further reduced by reducing the weight of the movable lens unit 51. The movable lens unit 51 is preferably composed of one or two lenses. In the illustrated example, the movable lens unit 51 has two movable lenses, and the display position in the depth direction of the display image IM is changed by integrally moving these two movable lenses in the optical axis AX direction. Can be made. By disposing the movable lens unit 51 for changing or changing the focal length in the relay optical unit 50, the movable lens unit 51 can be reduced in size, and the movable mechanism and the like can be simplified. In addition, by reducing the number of movable lenses constituting the movable lens unit 51, the lens weight of the movable lens unit 51 can be reduced. Thereby, it is not necessary to make the lens driving system 70 including a mechanism for driving the movable lens unit 51 large, and the enlargement and complexity of the apparatus can be prevented. Further, if the movable lens portion 51 is made of a plastic lens, further weight reduction can be achieved.

The projection optical system 13 changes the display position or display distance in the depth direction of the display image IM in accordance with the change of the focal length by the movable lens unit 51. As already described, the projection optical system 13 is configured to form the second intermediate image TI2 between the relay optical unit 50 and the third projection optical unit 60, and the focal length is changed or changed by the movable lens unit 51. When zooming is performed, the position of the second intermediate image TI2 moves along the optical axis AX. As a result, the display image IM moves from a position close to the display screen 20 (position of the display image IM1) to a position (display position of the display image IM2) far from the position close to the display screen 20 according to the degree of change in focal length or magnification. The position changes up to (the position of the image IM3) and is displayed continuously or intermittently. For example, if the display image IM is continuously displayed by changing the display distance from the farthest position to the nearest position at a high speed (for example, within 1/30 second), pseudo 3D virtual image display can be performed. it can.

The third projection optical unit 60 has a plurality of mirrors. In the illustrated example, the third projection optical unit 60 includes two mirrors MR1 and MR2. The mirror constituting the third projection optical unit 60 can be a convex surface, a concave surface, or a flat surface. In the case of a curved surface, the mirror is not limited to a spherical surface, and can be an aspherical surface, a free curved surface, or the like. The third projection optical unit 60, in cooperation with the display screen 20 described later, constitutes a virtual image enlargement projection system.

As shown in FIG. 2, the housing 14 has an opening 14a through which the display light HK passes, and a film-like or thin plate-like light transmission member 15 can be disposed in the opening 14a.

The display screen 20 is a plate-like member, and includes a first optical surface 21 provided on the observation side where the driver UN who is an observer or the driver's seat 6 (see FIG. 1A) side, the anti-observation side or the front window 8 side. And a second optical surface 22 provided on the surface. The first optical surface 21 is a concave curved surface and is an aspherical surface or a free curved surface. The second optical surface 22 is a convex curved surface (a concave curved surface when viewed from the observer side), and is an aspherical surface or a free curved surface. The first optical surface 21 is obtained by forming a half mirror coat 20b having a reflectance of, for example, 5 to 30% on the main body layer 20a as a base material, and appropriately reflects the display light HK. External light GK can be transmitted to a desired degree. On the second optical surface 22, an antireflection film and a protective coat are formed.

As shown in FIG. 4A, the display light HK reflected by the first optical surface 21 of the display screen 20 is guided to the pupil HT of the driver UN. Here, the virtual image light beam KK obtained by extending the display light HK behind the display screen 20 forms a display image (virtual image) IM at a predetermined position in front of the driver's pupil HT. The distance d1 from the pupil HT to the display screen 20 is, for example, about 0.5 to 1 m depending on the specifications of the vehicle body 2, and the distance d2 from the display screen 20 to the display image IM is variable, for example, 1 m More than about. The viewing angle is about 5 to 15 degrees. The eye box SY shown in FIG. 4B is set so as to cover the position of the standard driver UN pupil HT, and is set to a size of, for example, 10 to 15 cm in width and 5 to 8 cm in length.

〔Example〕
Examples of the projection optical system 13 of the present invention will be shown below.

Data of the projection optical system 13 of Example 1 is shown in Table 1 below. In Table 1 below, the number of the lens group constituting the projection optical system 13 is represented by “m”, the focal length of each lens group is represented by “fm”, and each lens when the display position is a long distance. The distance between the groups is represented by “dm (LR)”, and the distance between the lens groups when the display position is a short distance is represented by “dm (SR)”. The display element is represented by “DD” and the intermediate screen is represented by “mSC”. Further, the interval “dm” between the lens groups in the “M” column is the distance from the final optical system (that is, the third projection optical unit 60) to the pupil HT (that is, the position of the driver's eyes). The interval “dm” in the “N” column is the distance from the pupil HT to the display position of the virtual image. As for the interval “dm”, the interval between the third and fourth lens groups and the interval between the fourth and fifth lens groups are changed when the virtual image display is a long distance and a short distance, respectively. . In this embodiment, the long distance is set to about 50 m and the short distance is set to about 3 m. However, the fluctuation range of the distance between the third and fourth lens groups (described later) and the distance between the fourth and fifth lens groups (that is, By changing the amount of movement of the fourth lens group, these distance ranges can be made wider or narrower. Although not shown in the table, in actual use, the display screen 20 for displaying a virtual image is disposed between the sixth lens group and the driver's eyes (that is, the pupil HT). Note that the symbol “←” indicates that it is the same as the numerical value on the left side.
[Table 1]
m fm dm (LR) dm (SR)
DD
52.50 ←
1 45.000
315.00 ←
mSC
120.00 ←
2 120.000
173.33 ←
3 -74.270
16.00 6.00
4 63.903
488.78 498.78
5 -500.000
94.63 ←
6 271.462
M 1499.43 ←
N -50132.33 -2999.58

The size and viewing angle of the display element 11 of Example 1 are shown below.
Display element horizontal size (unit: mm): 9.86
Horizontal viewing angle (unit: degree): -12.2

In this embodiment, the magnification β2L of the relay optical unit 50 when the display position of the virtual image is farthest is 1.5 times, and the F value at the long distance projection after the third group emission is about 3.42. The eye box size at that time is secured to about 127 to 116 mm in the horizontal direction of the screen.

The projection optical system 13 of Example 1 includes a first projection optical unit 30, an intermediate screen mSC, and a second projection optical unit 40 in order from the display element 11 side with reference to FIG. The first projection optical unit 30 includes a first lens group. The second projection optical unit 40 includes second to sixth lens groups. Here, the second projection optical unit 40 includes a relay optical unit 50 including second to fourth lens groups, and fifth and sixth lens groups (specifically, mirrors MR1 and MR2). The third projection optical unit 60 is included. Among these, the fourth lens group of the relay optical unit 50 is a movable lens unit 51. The fourth lens group, which is the movable lens unit 51, performs focus adjustment or zooming by moving in the direction of the optical axis AX.

In this embodiment, the focal length of each lens group and the interval between each lens group are shown. However, each lens group may be composed of one lens or one mirror, or a plurality of lenses. Alternatively, it may be composed of a plurality of mirrors. Further, although not shown in the embodiment, the size of the entire optical system can be reduced by arranging a mirror that bends the optical path in the optical path of the optical system. The third projection optical unit 60 may be composed of at least one mirror. The third projection optical unit 60 preferably has a configuration of a mirror, particularly a free-form surface mirror, because the optical path to the display screen 20 can be handled freely and chromatic aberration does not occur.

In this embodiment, the light beam emitted from the second lens group is afocal, but it is not necessary to be afocal in particular. The size of the optical system, the focal length of each lens group, the F value, the magnification, etc. It can be changed to a desired configuration according to the specifications. Furthermore, in this embodiment, the position of the fourth lens group that is moved to change the focal length in the relay optical unit 50 is set to the position of the relay optical unit 50 in order to reduce the burden on the mechanism for moving the lens. Although it is set so as to be almost the same as the pupil position, it may be set at a different position in consideration of specifications and other factors in designing.

5A and 5B, the lens driving system 70 for moving the movable lens unit 51 in the optical axis AX direction will be described.

The lens driving system 70 drives a lens holder 72 that supports the movable lens unit 51, a guide member 73 that guides the movement of the movable lens unit 51 through the lens holder 72, and the movable lens unit 51 through the lens holder 72. An actuator 74 to be moved, a spring 75 acting on the movable lens unit 51 in a direction parallel to the moving direction of the movable lens unit 51, and a position information acquisition unit 78 for acquiring position information of the movable lens unit 51.

The lens holder 72 holds two

movable lenses

51 a and 51 b as the movable lens portion 51. The lens holder 72 has two bearing portions 72 a through which the two guide shafts 73 a constituting the guide member 73 are passed. The bearing portion 72a enables the lens holder 72 to move smoothly and without backlash along the guide shaft 73a. If the

movable lenses

51a and 51b constituting the movable lens unit 51 are plastic lenses, the weight of the movable lens unit 51 can be reduced, and the load on the actuator 74 described later is reduced. Furthermore, if these

movable lenses

51a and 51b are aspherical lenses, even if the movable lens unit 51 is configured with a small number, it is possible to design the aberration fluctuation when the movable lens unit 51 is moved small. This is desirable.

The guide member 73 has two guide shafts 73a, and these guide shafts 73a are supported on

support bodies

73d and 73e and fixed on a substrate (not shown). The guide shaft 73a is inserted into the bearing portion 72a of the lens holder 72 and slides in the optical axis AX direction. The guide member 73 has a role of maintaining the posture of the movable lens unit 51 when the movable lens unit 51 moves. That is, the guide member 73 not only enables high-speed movement of the movable lens unit 51 in the optical axis AX direction, but also stabilizes the posture of the movable lens unit 51 so that the posture of the movable lens unit 51 changes in inclination and the like. It does not occur.

The actuator 74 has a main body 74 a made up of a motor and other power sources, and a power transmission unit 74 b that transmits the driving force from the main body 74 a to the lens holder 72. The power transmission unit 74 b converts the rotational operation from the main body 74 a into a reciprocating operation along the optical axis AX and transmits the reciprocating operation to the lens holder 72. That is, the actuator 74 causes the lens holder 72 or the movable lens unit 51 to reciprocate at high speed along the optical axis AX. Here, it is desirable that the power transmission unit 74b has a direction to transmit power from the main body 74a to the lens holder 72, but does not act as a brake for the lens holder 72, but is not limited thereto. is not. For example, there may be one that transmits the movement amount of the main body 74a by a predetermined function. The actuator 74 may directly move the lens holder 72 in the direction of the optical axis AX like a linear motor, or may be another drive mechanism using a servo motor, a stepping motor, or the like.

The spring 75 is a coil spring or a helical spring. One end of the spring 75 is fixed to the support 73 d of the guide member 73, and the other end is fixed to the lens holder 72. The spring 75 has a movable end on the lens holder 72 side, and allows vibration of the lens holder 72 in the optical axis AX direction. Here, if the masses of the movable lens unit 51 and the lens holder 72 and the spring constant of the spring 75 are determined, the lens holder 72 is given a resonance frequency that is a specific frequency. Therefore, when the initial amplitude is given to the lens holder 72, the lens holder 72 repeats the vibration of the resonance frequency represented by the sine wave. Since the vibration of the lens holder 72 is gradually attenuated by frictional resistance or the like, it is necessary to secure the amplitude of the lens holder 72 by accelerating the movement of the lens holder 72 by the actuator 74. At this time, the driving frequency for reciprocating the lens holder 72 or the movable lens unit 51 by the actuator 74 is made to substantially coincide with the resonance frequency of the spring 75. Thereby, the load at the time of operating the actuator 74 can be efficiently reduced by utilizing the resonance of the spring 75. Here, “substantially coincidence” includes not only the case where both frequencies coincide with each other, but also includes a state where the drive frequency of the actuator 74 and the resonance frequency of the spring 75 are substantially equal. If the difference is in the range, it can be considered that they are substantially coincident. Even if the driving frequency for reciprocating the lens holder 72 by the actuator 74 and the resonance frequency of the spring 75 do not exactly coincide with each other, the load when operating the actuator 74 can be reduced if both frequencies are close to each other. In the above description, the vibration of the lens holder 72 caused by the spring 75 is not attenuated by the actuator 74. However, when the vibration of the lens holder 72 caused by the spring 75 is easily attenuated, the actuator 74 drives the lens holder 72 or the movable lens unit 51. Is the main. In this case as well, if the drive frequency and the resonance frequency are close, the load when operating the actuator 74 can be reduced.

The position information acquisition unit 78 includes a sensor that detects the position of the lens holder 72 in the optical axis AX direction. As the position information acquisition unit 78, a linear encoder can be used. As the position information acquisition unit 78, in addition to the linear encoder, a linear type MRE (Magneto-Resistive Element) in which resistance changes with the strength of the magnetic field, PSD (Position Sensitive Device), or the like can be used. When using the MRE, for example, a magnetic body is attached to the moving lens holder 72 side, and a sensor extending along the optical axis AX is installed on the fixed side. When using the PSD, for example, a blinking light source is attached to the moving lens holder 72 side, and a sensor extending along the optical axis AX is installed on the fixed side. For example, when using a servo motor, the position can be specified by reading the value of a rotary encoder directly connected to the shaft of the motor.

The configuration in which the position information acquisition unit 78 sequentially detects the position of the lens holder 72 or the movable lens unit 51 is not indispensable. A passage sensor 178 may be provided before the position of the maximum amplitude. As the passage sensor 178, for example, a photo interrupter or a Hall element can be used. The passage sensor 178 can detect that the amplitude of the movement of the lens holder 72 or the movable lens unit 51 is reduced and acceleration is necessary. Alternatively, the passage sensor 178 can adjust the timing for operating the actuator 74 in relation to the vibration period of the lens holder 72 and the like.

6A shows the position of the movable lens unit 51 or the lens holder 72 at the amplitude end where the spring 75 is most extended, and FIG. 6B shows the position of the movable lens unit 51 or the lens holder 72 at the amplitude end where the spring 75 is most contracted. Indicates the position. As shown in FIG. 6A, when the spring 75 is extended most, the movable lens portion 51 and the like are positioned on the most + Y side in the optical axis AX direction, and the spring 75 is in a direction contracted with respect to the movable lens portion 51 and the like. Acts in the Y direction. As shown in FIG. 6B, when the spring 75 is most contracted, the movable lens portion 51 and the like are positioned closest to the −Y side in the optical axis AX direction, and the spring 75 extends in the direction of the movable lens portion 51 and the like. Acts in the + Y direction. When the movable lens unit 51 and the like are driven by the actuator 74, when the spring 75 extends from the neutral or neutral state toward the state of FIG. 6A, the inertia of the movable lens unit 51 and the like is used to resist the force of the spring 75. Thus, the movable lens unit 51 and the like can be moved efficiently. When the spring 75 reaches the state shown in FIG. 6A, the spring 75 becomes the longest and the movement of the movable lens unit 51 etc. stops and the moving direction of the movable lens unit 51 etc. reverses. Therefore, the load of the actuator 74 when the actuator 74 reversely drives the movable lens unit 51 and the like is reduced, and there is an effect of reducing the electric power required for the reverse drive of the actuator 74. The above is the case where the spring 75 extends from the neutral state toward the state of FIG. 6A, but the same applies when the spring 75 contracts from the neutral state toward the state of FIG. 6B. The movable lens portion 51 and the like can be efficiently moved against the force of the spring 75 by utilizing the inertia. When the spring 75 reaches the state shown in FIG. 6B, the spring 75 is contracted most and the movement of the movable lens unit 51 etc. stops and the moving direction of the movable lens unit 51 etc. is reversed. Also in this case, the load on the actuator 74 when the driving of the movable lens unit 51 and the like is reversed by the actuator 74 is reduced, and the power can be reduced.

FIG. 7 is a block diagram illustrating a control system of the image display device (optical device) 100 shown in FIG. 1A and the like. The image display apparatus 100 includes a main control unit 90 in addition to the drawing unit 10 described above.

The drawing unit 10 includes, as the circuit portion 19, a display control unit 18 that operates the drawing device 12 including the display element 11 and the like, and an actuator drive control unit 81 that operates the actuator 74 for the movable lens unit 51. The virtual image display optical system 113 is a combination of the projection optical system 13 and the drawing device 12.

The display control unit 18 operates the drawing device 12 under the control of the main control unit 90 to display a three-dimensional display image IM whose virtual image distance or projection distance changes behind the display screen 20. The display control unit 18 generates a display image IM to be displayed by the projection optical system 13 from the display information received via the main control unit 90. The display image IM can be, for example, a sign such as a display frame located in the periphery including the depth position direction with respect to an automobile, a bicycle, a pedestrian, and other objects existing behind the display screen 20.

The actuator drive control unit 81 operates the actuator 74 based on the position detection result of the position information acquisition unit 78 under the control of the main control unit 90 to adjust the position of the display image IM displayed by the projection optical system 13. By performing drive control of the actuator 74 using information from the position information acquisition unit 78 that acquires position information of the movable lens unit 51, it is possible to monitor whether the operation of the movable lens unit 51 is in an intended state. Therefore, for example, by performing feedback control, the reliability of the operation of the movable lens unit 51 can be improved. Further, by obtaining the position information of the movable lens unit 51, an accurate and appropriate optical operation according to the state of the optical system becomes possible. For example, when the optical system is the projection optical system 13, the projection distance is variable by the movable lens unit 51. However, by monitoring the position of the movable lens unit 51, desired display according to the projection distance can be performed. . Specifically, the actuator drive control unit 81 appropriately operates the actuator 74 to displace the movable lens unit 51 along the optical axis AX so that the display position of the display image IM is a long distance, a middle distance, a short distance, and the like. Change periodically. At this time, the display control unit 18 changes the content displayed on the display element 11 of the drawing device 12 corresponding to the display position or display distance of the display image IM, and displays the display image IM at the display position in the desired depth direction. Can be made. That is, driving-related information can be displayed three-dimensionally.

The main control unit 90 collects information from a camera, various sensors, and the like provided in the vehicle body 2 to make the operation of the drawing unit 10 harmonized with the operation of the vehicle body 2.

FIG. 8 is a diagram for explaining an example of the operation of the lens driving system 70 shown in FIG. 5A and the like, and shows an example of a change with time of the position of the lens holder 72 in the optical axis AX direction. In this case, the lens holder 72 vibrates at a resonance frequency represented by a sine wave. Here, the frequency and period of vibration of the lens holder 72 are determined by the mass of the movable lens unit 51 and the lens holder 72 and the spring constant of the spring 75. Therefore, if the movable lens portion 51 is lightened and the spring constant of the spring 75 is increased, the frequency is increased and the period is shortened. Specifically, when the mass of the movable lens unit 51 and the lens holder 72 is M (kg) and the spring constant of the spring 75 is k (kg / sec ² ), the resonance frequency F (1 / sec) of the lens holder 72 and the like. ) Or period T (sec) is
F = 1 / T = 2π√ (k / M)
Given in. That is, when the mass of the movable lens unit 51 and the lens holder 72 and the resonance frequency F are determined, the spring constant k of the spring 75 is
k = 4π · M · F ²
Given in. As shown in FIG. 5A, when two identical springs 75 are used in parallel, the spring constant k0 of one spring 72 is k0 = k / 2, and k0 = 2π · M · F ^2.
Given in. Specifically, when the combined spring constant k of the pair of springs 75 is approximately 1.42 × 10 ³ (kg / sec ² ) and the mass M of the movable lens unit 51 and the lens holder 72 is 0.1 kg, The resonance frequency F is about 60 Hz, and the vibration period at that time is 1/60 seconds.

In the example shown in FIG. 8, for example, when the movable lens unit 51 is to be moved to three positions A1 to A3 set at equal intervals, it can be seen that the movable lens unit 51 exists at the target position at times B1 to B3. The drawing device 12 causes the display element 11 to perform display at times B1 to B3 adjusted based on the detection output of the position information acquisition unit 78 and the vicinity thereof. Thereby, the display image (virtual image) IM can be formed at a front position corresponding to the position of the movable lens unit 51 while moving the movable lens unit 51 to a plurality of locations set in stages (see FIG. 3).

When the driving force is applied to the lens holder 72 by the actuator 74, it is not necessary to continue after the vibration of the spring 75 starts, and the driving force is applied from the actuator 74 using the detection output of the position information acquisition unit 78. Timing control can be performed. For example, the moving speed of the movable lens unit 51 is monitored based on the detection output of the position information acquisition unit 78, and the absolute value (maximum speed) of the moving speed v of the movable lens unit 51 at a position where the spring 75 is neutral or neutral. Value) is equal to or less than a predetermined value A (m / s) corresponding to the resonance frequency, that is, when | v | ≦ A, the driving force of the actuator 74 is turned ON, and the moving speed v of the movable lens unit 51 is specified. By turning OFF the driving force of the actuator 74 at a timing exceeding the value A, it is possible to prevent the reciprocating motion of the movable lens unit 51 from being attenuated and continue the movement of the movable lens unit 51 at a desired speed. Become.

Regarding the monitoring of the operation state of the lens holder 72 or the movable lens unit 51, not only the lower limit of the moving speed of the lens holder 72 or the movable lens unit 51, but an upper limit may be set, for example, within ± 1% of the target speed or ± The control may be performed by determining an allowable range in advance, for example, by setting within 2%. Note that the timing control of the actuator 74 is not limited to monitoring the speed of the lens holder 72 or the movable lens unit 51, but various actuators such as the amplitude of the lens holder 72 or the movable lens unit 51 are monitored to detect the actuator 74. 74 timing control of the operation can be performed. For example, an allowable range can be set for the resonance frequency of the lens holder 72 or the movable lens unit 51. That is, when the drive frequency of the actuator 74 is higher than the resonance frequency of the spring 75, the vibration period of the spring 75 gradually decreases when the operation of the actuator 74 is turned off. It is possible to determine whether or not it is necessary. In this method, considering the case where the lens holder 72 is driven at 60 Hz, for example, the time between both ends of the expansion and contraction or both ends of the amplitude is set to a certain time set to a time longer than, for example, 8.3 msec or longer than 8.3 msec. If the time is longer than the time, a method may be considered in which the operation of the actuator 74 is turned on to maintain the amplitude and the moving speed.

The ON / OFF timing of the driving force of the actuator 74 is not limited to monitoring the operation state of the lens holder 72 or the movable lens unit 51, but is permitted in advance for the operation state or operation items such as the movement amount and speed of the actuator 74. When the operating state of the actuator 74 is within the allowable range, the driving force of the actuator 74 is turned off, and when the operating state of the lens holder 72 and the like exceeds the allowable range, A method of turning on the driving force of the actuator 74 until the time is reached is also conceivable. The permissible range determination here may be performed at the driving speed of the actuator 74, or conditions such as amplitude may be added in addition to the driving speed. When such a driving method is used, it is necessary to monitor the operation of the actuator 74, but the position information acquisition unit 78 is not essential.

When the operating state of the lens holder 72 or the movable lens unit 51 or the operating state of the actuator 74 is monitored and the ON / OFF control of the driving force of the actuator 74 is performed, even when the operating state or the operating item falls within the allowable range, The control of turning off the driving force of the actuator 74 can be performed only when the allowable range is maintained within the allowable range for a predetermined time set in advance. By adopting such control, it is possible to expect an effect that it is possible to maintain a long time until the actuator 74 is turned off after the driving force of the actuator 74 is turned off. In this way, it is desirable that power consumption for driving the actuator 74 can be suppressed by making the time for which the driving force of the actuator 74 is OFF as long as possible.

The transmission of the driving force of the actuator 74 to the lens holder 72 is not limited to when the vibration of the lens holder 72 is weakened, but can be performed at a specific timing or phase during one vibration of the lens holder 72. For example, when the lens holder 72 is moving in the direction of contraction from the state in which the spring 75 is extended, the period from the position where the spring 75 is extended to the neutral or neutral position of the spring 75 (see section TA1 in FIG. 8). ), The driving force of the actuator 74 is turned OFF, and the spring 75 acts in the opposite direction during the period until the spring 75 is further contracted from the neutral position to reach the most contracted state (see section TA2 in FIG. 8). The driving force of the actuator 74 is turned on so that the vibration is not attenuated. Further, during the reverse movement, during the period from the position where the spring 75 is most contracted to the position where the spring 75 reaches the neutral position (refer to the section TA3 in FIG. 8), the driving force of the actuator 74 is turned OFF, During the period until the spring is further extended beyond the neutral position (see section TA4 in FIG. 8), the spring 75 operates in the opposite direction, so that the driving force of the actuator 74 is turned on so that the vibration is not attenuated. . Note that the above is an example, and it is also possible to perform control such that the driving force of the actuator 74 is turned on only in one of the sections TA2 and TA4. Further, the actuator 74 accelerates the lens holder 72 at the timing when the moving speed of the lens holder 72 becomes maximum, or the actuator 74 at the timing when the moving speed of the lens holder 72 decreases near the amplitude end of the lens holder 72. The lens holder 72 can also be accelerated.

Regarding the control when starting the movement of the lens holder 72 or the movable lens unit 51, for example, a load is gradually applied to the actuator 74, for example, and first, the displacement of the lens holder 72 or the like is reduced to start the vibration operation with a small amplitude. Then, a method of increasing the speed while gradually increasing the amplitude and driving at the resonance frequency when the desired amplitude is reached can be considered. At this time, it is possible to control the load on the actuator 74 in a relatively small state, but on the other hand, there also arises a problem that the rise time until the movement of the movable lens unit 51 becomes a steady state becomes long. Therefore, in the case where it is necessary to increase the rise time with respect to the movement of the movable lens unit 51 or in an application, for example, the driving speed by the actuator 74 is increased at a stroke to resonate the movable lens unit 51 or the like with a desired amplitude. For example, although the load is applied to the actuator 74 at the start, there is an advantage that the rise time until the steady state is reached can be shortened. Further, the load of the actuator 74 and the amplitude of the movable lens unit 51 and the like are well balanced, and the amplitude and frequency at the time of start-up are controlled, so that the movement of the movable lens unit 51 is in a steady state within a desired time. Smooth start-up control in which the load on the actuator 74 is reduced can also be performed.

In the optical element driving method described above, since the actuator 74 is operated while using the action of the spring 75, the load on the actuator 74 for driving the movable lens unit 51 can be reduced, and low power consumption and high durability can be achieved. In addition, the movable lens unit 51 can be driven at high speed.

[Second Embodiment]
Hereinafter, an optical element driving method according to the second embodiment and an optical apparatus using the optical element driving method will be described. The optical element driving method and the like of the second embodiment are modifications of the optical element driving method and the like of the first embodiment, and items that are not particularly described are the same as those of the first embodiment.

As shown in FIG. 9, in the lens driving system 70 used in the optical element driving method according to the second embodiment, the

springs

75 and 175 are attached to the guide member 73. More specifically, the

springs

75 and 175 are wound around the two guide shafts 73 a of the guide member 73. In this case, the expansion and contraction directions of the

springs

75 and 175 can be easily matched with the extending direction of the guide member 73, and the power from the

springs

75 and 175 can be efficiently transmitted to the lens holder 72 or the movable lens unit 51. Since the

springs

75 and 175 are coil springs wound around the guide shaft 73a of the guide member 73, the

springs

75 and 175 are securely held by the guide member 73. A behavior of 72 is stable and desirable.

In the illustrated example, two

springs

75 and 175 are attached to each guide shaft 73a with the lens holder 72 and the like interposed therebetween. In total, four

springs

75 and 175 are attached. The guide shaft 73a extends so as to be parallel to the lens moving direction. When the lens holder 72 or the like moves, the four

springs

75 and 175 expand and contract to ± Y parallel to the lens moving direction. To do. Here, when one spring 75 of the two

springs

75 and 175 attached to the same guide shaft 73a is extended, the other spring 175 is contracted. Since both the

springs

75 and 175 are expanded and contracted along the guide shaft 73a, the action of the force of both the

springs

75 and 175 is the same as the lens moving direction, and errors such as distortion and deflection when moving the lens holder 72 are caused. It is hard to occur.

In the embodiment described above, the lens holder 72 is moved in the optical axis AX direction by the lens driving system 70. However, the movable lens unit 51 can also be moved directly in the optical axis AX direction by the lens driving system 70.

Instead of moving the movable lens unit 51 by the lens driving system 70, optical elements such as a filter and a diffusion plate can be moved. In particular, the movable lens unit 51 shown in FIG. 3 is fixed, a diffusing plate is disposed at the position of the second intermediate image TI2, and the diffusing plate is displaced along the optical axis AX by a mechanism similar to the lens driving system 70. Since the second intermediate image TI2 is forcibly formed and moved on the diffusion plate, the display position of the display image (virtual image) IM can be changed at high speed according to the movement of the diffusion plate.

The spring 75 is not limited to a coil spring, and any spring that can increase the amount of displacement of a lens or the like can be used, and a leaf spring or other various springs can be used. Note that the number of springs 75 is not limited to two or more, and one spring 75 can be used. Further, the spring 75 may be arranged to be inclined without being parallel to the optical axis AX.

The display position of the display image (virtual image) IM is not limited to the three places exemplified in the above embodiment, and can be set to an appropriate number of four or more places. The display of the display image IM can be performed continuously or intermittently by changing the position.

As the guide member 73 of the lens driving system 70, it is not necessary to use a shaft-like member, and various methods for smoothly guiding the movement of the lens holder 72 and the like can be used. Even when the guide shaft 73a is used, it is not necessary to use the two guide shafts 73a. If the behavior when displacing the movable lens unit 51 is stabilized, the guide shaft is omitted or one guide shaft is used. If the stability is not easy, three or more guide shafts can be used. Normally, by using two or more guide shafts to balance their arrangement, it is possible to reduce the tilt, vibration, and the like of the movable lens unit 51 during driving.

The projection optical system 13 shown in FIG. 3 and the like is merely an example, and the optical configuration of the projection optical system 13 can be changed as appropriate. For example, an optical system that does not form the first intermediate image TI1 can be used, and an optical system that does not form the first and second intermediate images TI1 and TI2.

The projection optical system 13 is not limited to one that projects a virtual image, but may be one that forms a magnified image or a reduced image that is a real image. The purpose of moving or displacing the movable lens unit 51 is not limited to changing the projection position and the projection size, but can change the focusing position and the projection size at the time of image formation independently.

The display screen 20 as a combiner is not limited to being installed separately from the front window 8, and can use the inner surface of the front window 8 or be embedded in the front window 8.

In the above embodiment, one or more springs 75 are provided along with the actuator 74. For example, if there is one spring 75, the configuration is simplified and the cost can be reduced. Further, if there are two or

more springs

75 and 175, it is easy to balance the action of the force, so that the posture and operation of the movable lens unit 51 can be stabilized, for example.

Claims

An optical element driving method for moving at least one movable optical element constituting an optical system along an optical axis direction,
Along with the actuator, a spring acting on the movable optical element in a direction parallel to at least the moving direction of the movable optical element is provided,
An optical element driving method for operating an actuator while using the action of the spring.
2. The optical element driving method according to claim 1, wherein a driving frequency for reciprocating the movable optical element by the actuator substantially matches a resonance frequency of the spring.
3. The optical element driving method according to claim 1, further comprising a guide member that holds a posture of the movable optical element when the movable optical element moves.
4. The optical element driving method according to claim 3, wherein the spring is attached to the guide member.
The optical element driving method according to claim 4, wherein the spring is a coil spring wound around an axis of the shaft-shaped guide member.
The optical element driving method according to any one of claims 1 to 5, wherein the movable optical element includes three or less lenses.
The optical element driving method according to any one of claims 1 to 6, wherein one or more of the springs are provided in association with the actuator.
The optical element driving method according to any one of claims 1 to 7, wherein drive control of the actuator is performed using information from a position information acquisition unit that acquires position information of the movable optical element.
An optical system for forming a projected image;
An actuator for moving at least one movable optical element constituting the optical system along an optical axis direction;
A spring acting on the movable optical element in a direction parallel to at least the driving direction of the movable optical element;
An optical device comprising: a drive control unit that operates the actuator while using the action of the spring.
A positional information acquisition unit that acquires positional information of the movable optical element;
The optical device according to claim 9, wherein the drive control unit performs drive control of the actuator using the position information from the position information acquisition unit.