JP7338403B2 - Optical deflectors, image projection devices, head-up displays, laser headlamps, head-mounted displays, object recognition devices, and vehicles - Google Patents

Description

The present invention relates to an optical deflector, an image projection device, a head-up display, a laser headlamp, a head-mounted display, an object recognition device, and a vehicle.

In recent years, an optical deflector realized by MEMS (Micro Electro Mechanical Systems) technology has been used as a compact optical scanning means installed in image display devices typified by projectors and sensing devices typified by LiDAR (Light Detection And Ranging). has been actively developed, and some applications have started to be put to practical use. Optical deflectors used for these applications are required to have a mirror diameter of 1 mm or more and a mirror deflection angle of 10 degrees or more, and both the mirror size and deflection angle tend to increase compared to conventional optical deflectors for optical communication. is commonly known.

In addition, in order to obtain the correct optical deflection angle in optical scanning and to control the light projection timing of the LiDAR and the driving of the optical deflector, a piezoelectric sensor is provided in parallel with the piezoelectric actuator of the optical deflector, and the output signal is used as the basis of the sensor. A method for detecting the angle of an optical deflector is generally known.

In addition, in order to completely match the signal obtained by the piezoelectric sensor with the amount of displacement of the piezoelectric actuator, data for angle correction measured in advance was stored in the memory circuit as a table. A configuration is disclosed in which the maximum deflection angle of the mirror is calculated by correcting the value obtained at times and controlled to a desired deflection angle. (For example, see Patent Document 1)

However, the conventional detection method using a piezoelectric sensor is affected by the drive amplitude, temperature, and drive frequency of the optical deflector, so the piezoelectric actuator response to the deflection angle, which is the swing angle of the optical deflector, is not constant. Therefore, even if the amplitude of the output is the same, the deflection angle of the optical deflector obtained is not accurate, and there is room for improvement in terms of improving the accuracy in calculating the mirror deflection angle in the optical deflector. That is, an optical deflector with high accuracy in detecting the swing angle has been demanded.

An optical deflector according to an aspect of the disclosed technology includes a reflecting portion having a reflecting surface that reflects light, a supporting portion connected at one end to the reflecting portion, and a fixed portion connected to the other end of the supporting portion. a piezoelectric member that deforms the supporting portion to swing the reflecting portion; a frequency detecting portion that detects the frequency of the drive signal input to the piezoelectric member; and a detection signal corresponding to the deformation of the supporting portion. and a displacement amount detection unit that detects the signal strength of the detection signal , and at least frequency information of the frequency detected by the frequency detection unit and the displacement amount detected by the displacement detection unit and a calculation unit for calculating the swing angle of the reflection unit based on the signal intensity .

According to the disclosed technique, it is possible to improve the detection accuracy of the swing angle of the optical deflector.

1 is a schematic diagram of an example optical scanning system; FIG. 1 is a hardware configuration diagram of an example of an optical scanning system; FIG. It is a functional block diagram of an example of a control device. 4 is a flowchart of an example of processing related to an optical scanning system; 1 is a schematic diagram of an example of a vehicle equipped with a head-up display device; FIG. 1 is a schematic diagram of an example of a head-up display device; FIG. 1 is a schematic diagram of an example of an image forming apparatus equipped with an optical writing device; FIG. 1 is a schematic diagram of an example of an optical writing device; FIG. 1 is a schematic diagram of an example vehicle equipped with a lidar device; FIG. 1 is a schematic diagram of an example lidar device; FIG. It is a schematic diagram explaining an example of composition of a laser light source. It is a schematic diagram explaining an example of composition of a laser headlamp. It is a schematic perspective view which shows an example of a structure of a head mounted display. It is a figure which shows an example of a part of structure of a head mounted display. 1 is a schematic diagram illustrating an example of a packaged mobile device; FIG. 3 is a configuration diagram of an optical deflector in the first embodiment; FIG. It is a lineblock diagram of mobile (1) in a 1st embodiment. It is a lineblock diagram of mobile (2) in a 1st embodiment. It is a block diagram of the mobile device (3) in 1st Embodiment. It is a block diagram of the mobile device (4) in 1st Embodiment. FIG. 2 is an explanatory diagram of an optical deflector in the first embodiment; FIG. FIG. 10 is a configuration diagram of an optical deflector in a second embodiment; FIG. 11 is a configuration diagram of an optical deflector in a third embodiment; It is a block diagram of the optical deflector in 4th Embodiment. It is a lineblock diagram of a movable device in a 5th embodiment. It is sectional drawing of the movable apparatus in 5th Embodiment. It is a lineblock diagram of other movable devices in a 5th embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail. In addition, the same reference numerals are assigned to the same members and the description thereof is omitted.

[Optical scanning system]
First, an optical scanning system to which the movable device of this embodiment is applied will be described in detail with reference to FIGS. 1 to 4. FIG.

A schematic diagram of an example of an optical scanning system is shown in FIG. As shown in FIG. 1, an optical scanning system 10 is a system that optically scans a surface 15 to be scanned by deflecting light emitted from a light source device 12 by a reflecting surface 14 of a movable device 13 under the control of a control device 11 . be.

The optical scanning system 10 comprises a control device 11 , a light source device 12 and a movable device 13 having a reflecting surface 14 .

The control device 11 is an electronic circuit unit including, for example, a CPU (Central Processing Unit) and an FPGA (Field-Programmable Gate Array). The movable device 13 is, for example, a MEMS (Micro Electromechanical Systems) device having a reflecting surface 14 and capable of moving the reflecting surface 14 . The light source device 12 is, for example, a laser device that emits laser light. Note that the scanned surface 15 is, for example, a screen.

The control device 11 generates control commands for the light source device 12 and the movable device 13 based on the acquired optical scanning information, and outputs drive signals to the light source device 12 and the movable device 13 based on the control commands.

The light source device 12 irradiates the light source based on the input drive signal. The movable device 13 moves the reflecting surface 14 in at least one of the directions of one axis and the directions of two axes based on the input drive signal.

As a result, for example, the reflecting surface 14 of the movable device 13 is reciprocally moved in two axial directions within a predetermined range under the control of the control device 11 based on image information, which is an example of optical scanning information, and the light is incident on the reflecting surface 14 . An arbitrary image can be projected onto the surface 15 to be scanned by deflecting the irradiation light from the light source device 12 around a certain axis and performing optical scanning. In addition, the detail of the movable apparatus of this embodiment and the detail of control by a control apparatus are mentioned later.

Next, a hardware configuration of an example of the optical scanning system 10 will be described with reference to FIG. FIG. 2 is a hardware configuration diagram of an example of the optical scanning system 10. As shown in FIG. As shown in FIG. 2, the optical scanning system 10 includes a control device 11, a light source device 12 and a movable device 13, which are electrically connected to each other. Among these, the control device 11 includes a CPU 20 , a RAM 21 (Random Access Memory), a ROM 22 (Read Only Memory), an FPGA 23 , an external I/F 24 , a light source device driver 25 and a movable device driver 26 .

The CPU 20 is an arithmetic device that reads programs and data from a storage device such as a ROM 22 onto a RAM 21 and executes processing to achieve overall control and functions of the control device 11 .

The RAM 21 is a volatile storage device that temporarily holds programs and data.

The ROM 22 is a nonvolatile storage device that can retain programs and data even when the power is turned off, and stores processing programs and data that the CPU 20 executes to control each function of the optical scanning system 10 . there is

The FPGA 23 is a circuit that outputs control signals suitable for the light source device driver 25 and the movable device driver 26 according to the processing of the CPU 20 .

The external I/F 24 is, for example, an interface with an external device, network, or the like. External devices include, for example, host devices such as PCs (Personal Computers), and storage devices such as USB memories, SD cards, CDs, DVDs, HDDs, and SSDs. The network is, for example, a CAN (Controller Area Network) of an automobile, a LAN (Local Area Network), the Internet, or the like. The external I/F 24 may be configured to enable connection or communication with an external device, and the external I/F 24 may be prepared for each external device.

The light source device driver 25 is an electric circuit that outputs a drive signal such as a drive voltage to the light source device 12 according to the input control signal.

The mobile device driver 26 is an electric circuit that outputs a drive signal such as a drive voltage to the mobile device 13 according to the input control signal.

In the control device 11 , the CPU 20 acquires optical scanning information from an external device or network via the external I/F 24 . It should be noted that any configuration may be used as long as the CPU 20 can acquire the optical scanning information. A storage device may be provided and the optical scanning information may be stored in the storage device.

Here, the optical scanning information is information indicating how to optically scan the surface 15 to be scanned. For example, when an image is displayed by optical scanning, the optical scanning information is image data. Further, for example, when optical writing is performed by optical scanning, the optical scanning information is writing data indicating the writing order and writing location. In addition, for example, when object recognition is performed by optical scanning, the optical scanning information is irradiation data indicating the timing and irradiation range of irradiation with light for object recognition.

The control device 11 can implement the functional configuration described below by means of commands from the CPU 20 and the hardware configuration shown in FIG.

Next, the functional configuration of the controller 11 of the optical scanning system 10 will be described with reference to FIG. FIG. 3 is a functional block diagram of an example of the controller of the optical scanning system.

As shown in FIG. 3, the control device 11 has a control section 30 and a drive signal output section 31 as functions.

The control unit 30 is implemented by, for example, the CPU 20 and the FPGA 23 , acquires optical scanning information from an external device, converts the optical scanning information into control signals, and outputs the control signals to the drive signal output unit 31 . For example, the control unit 30 acquires image data as optical scanning information from an external device or the like, generates a control signal from the image data through predetermined processing, and outputs the control signal to the drive signal output unit 31 . The drive signal output unit 31 is realized by the light source device driver 25, the movable device driver 26, etc., and outputs a drive signal to the light source device 12 or the movable device 13 based on the input control signal.

The drive signal is a signal for controlling driving of the light source device 12 or the movable device 13 . For example, in the light source device 12, it is a driving voltage for controlling the irradiation timing and irradiation intensity of the light source. Further, for example, in the movable device 13 , it is a drive voltage for controlling the timing and movable range for moving the reflecting surface 14 of the movable device 13 .

Next, a process of optically scanning the surface 15 to be scanned by the optical scanning system 10 will be described with reference to FIG. FIG. 4 is a flowchart of an example of processing related to the optical scanning system.

In step S11, the control unit 30 acquires optical scanning information from an external device or the like.

In step S<b>12 , the control section 30 generates a control signal from the acquired optical scanning information and outputs the control signal to the drive signal output section 31 .

In step S13, the drive signal output unit 31 outputs a drive signal to the light source device 12 and the movable device 13 based on the input control signal.

In step 14, the light source device 12 performs light irradiation based on the input drive signal. Also, the movable device 13 moves the reflecting surface 14 based on the input drive signal. By driving the light source device 12 and the movable device 13, light is deflected in an arbitrary direction and optically scanned.

In the optical scanning system 10, one control device 11 has a device and functions for controlling the light source device 12 and the movable device 13. The control device for the light source device and the control device for the movable device, It may be provided separately.

In the optical scanning system 10, the control unit 30 of the light source device 12 and the movable device 13 and the drive signal output unit 31 are provided in one control device 11, but these functions exist separately. Alternatively, for example, a configuration in which a drive signal output device having a drive signal output section 31 is provided separately from the control device 11 having the control section 30 may be employed. In the optical scanning system 10, the movable device 13 having the reflecting surface 14 and the control device 11 may constitute an optical deflection system that deflects the light.

[Image projection device]
Next, an image projection device to which the movable device of this embodiment is applied will be described in detail with reference to FIGS. 5 and 6. FIG.

FIG. 5 is a schematic diagram of an embodiment of an automobile 400 equipped with a head-up display device 500, which is an example of an image projection device. Also, FIG. 6 is a schematic diagram of an example of the head-up display device 500 .

An image projection device is a device that projects an image by optical scanning, such as a head-up display device.

As shown in FIG. 5, the head-up display device 500 is installed near the windshield (windshield 401 etc.) of the automobile 400, for example. The projection light L emitted from the head-up display device 500 is reflected by the windshield 401 and travels toward the observer (driver 402) who is the user. Accordingly, the driver 402 can visually recognize the image or the like projected by the head-up display device 500 as a virtual image. A combiner may be installed on the inner wall surface of the windshield so that the user can visually recognize the virtual image by projected light reflected by the combiner.

As shown in FIG. 6, head-up display device 500 emits laser light from red, green, and blue laser light sources 501R, 501G, and 501B. The emitted laser light passes through an incident optical system composed of collimating lenses 502, 503, and 504 provided for each laser light source, two dichroic mirrors 505 and 506, and a light amount adjusting section 507, It is deflected by a movable device 13 having a reflective surface 14 . The deflected laser light passes through a projection optical system composed of a free-form surface mirror 509, an intermediate screen 510, and a projection mirror 511, and is projected onto the screen. In the head-up display device 500, the laser light sources 501R, 501G and 501B, the collimator lenses 502, 503 and 504, and the dichroic mirrors 505 and 506 are unitized as a light source unit 530 by an optical housing.

The head-up display device 500 projects the intermediate image displayed on the intermediate screen 510 onto the windshield 401 of the automobile 400 so that the driver 402 can visually recognize the intermediate image as a virtual image.

The respective color laser beams emitted from the laser light sources 501R, 501G, and 501B are collimated by collimating lenses 502, 503, and 504, respectively, and combined by two dichroic mirrors 505 and 506 serving as combining units. The combined laser light is two-dimensionally scanned by the movable device 13 having the reflecting surface 14 after the light amount is adjusted by the light amount adjusting unit 507 . The projection light L that has been two-dimensionally scanned by the movable device 13 is reflected by the free-form surface mirror 509 and corrected for distortion, and then converged on the intermediate screen 510 to display an intermediate image. The intermediate screen 510 is composed of a microlens array in which microlenses are two-dimensionally arranged, and magnifies the projection light L incident on the intermediate screen 510 in microlens units.

The movable device 13 reciprocates the reflecting surface 14 in two axial directions, and two-dimensionally scans the projection light L incident on the reflecting surface 14 . The drive control of this movable device 13 is performed in synchronization with the light emission timings of the laser light sources 501R, 501G, and 501B.

The head-up display device 500 has been described above as an example of the image projection device, but the image projection device may be any device that projects an image by performing optical scanning with the movable device 13 having the reflecting surface 14. . For example, a projector that is placed on a desk or the like and projects an image onto a display screen, is mounted on a mounting member that is worn on the head of an observer, etc., and projects onto a reflective transmission screen that the mounting member has, or uses the eyeball as a screen. The same can be applied to a head-mounted display device or the like that projects an image.

In addition, the image projection device is used not only for vehicles and mounting members, but also for mobile objects such as aircraft, ships, and mobile robots, or working robots that operate objects to be driven such as manipulators without moving from the spot. It may be mounted on a non-moving object.

The head-up display device 500 is an example of the "head-up display" described in the claims. Also, the automobile 400 is an example of the "vehicle" described in the claims.

[Optical writing device]
Next, an optical writing device to which the movable device 13 of this embodiment is applied will be described in detail with reference to FIGS. 7 and 8. FIG.

FIG. 7 shows an example of an image forming apparatus in which the optical writing device 600 is incorporated. Also, FIG. 8 is a schematic diagram of an example of an optical writing device.

As shown in FIG. 7, the optical writing device 600 is used as a constituent member of an image forming apparatus typified by a laser printer 650 having a printer function using laser light. In the image forming apparatus, the optical writing device 600 performs optical writing on the photosensitive drum by optically scanning the photosensitive drum, which is the surface to be scanned 15, with one or more laser beams.

As shown in FIG. 8, in an optical writing device 600, a laser beam from a light source device 12 such as a laser element passes through an imaging optical system 601 such as a collimating lens, and then passes through a movable device 13 having a reflecting surface 14. Axially or biaxially deflected. The laser beam deflected by the movable device 13 then passes through a scanning optical system 602 consisting of a first lens 602a, a second lens 602b, and a reflecting mirror portion 602c, and passes through the surface to be scanned 15 (for example, a photosensitive drum or photosensitive paper). ) to perform optical writing. The scanning optical system 602 forms a spot-like light beam on the surface 15 to be scanned. Also, the movable device 13 having the light source device 12 and the reflecting surface 14 is driven based on the control of the control device 11 .

Thus, the optical writing device 600 can be used as a component of an image forming apparatus having a printer function using laser light. In addition, by making the scanning optical system different so that optical scanning can be performed not only in one axial direction but also in two axial directions, a laser label device or the like that prints by deflecting a laser beam onto a thermal medium, performing optical scanning, and heating the media. can be used as a component of the image forming apparatus.

The movable device 13 having the reflecting surface 14 applied to the optical writing device consumes less power for driving than a rotating polygonal mirror using a polygon mirror or the like, so it contributes to power saving of the optical writing device. Advantageous. In addition, since wind noise when the movable device 13 vibrates is smaller than that of the rotating polygon mirror, it is advantageous for improving the quietness of the optical writing device. The optical writing device requires an overwhelmingly smaller installation space than the rotary polygon mirror, and the amount of heat generated by the movable device 13 is also very small. be.

[Object recognition device]
Next, an object recognition device to which the movable device of the present embodiment is applied will be described in detail with reference to FIGS. 9 and 10. FIG.

FIG. 9 is a schematic diagram of a vehicle equipped with a LiDAR (Laser Imaging Detection and Ranging) device, which is an example of an object recognition device. Also, FIG. 10 is a schematic diagram of an example of a lidar device.

An object recognition device is a device that recognizes an object in a target direction, such as a lidar device.

As shown in FIG. 9, the lidar device 700 is mounted on, for example, an automobile 701, optically scans a target direction, and receives reflected light from a target object 702 existing in the target direction. to recognize

As shown in FIG. 10, the laser light emitted from the light source device 12 passes through an incident optical system composed of a collimating lens 703, which is an optical system that converts diverging light into substantially parallel light, and a plane mirror 704, and is reflected. A movable device 13 having a surface 14 is scanned in one or two axes. Then, the light is projected onto an object 702 in front of the device through a projection lens 705 or the like, which is a projection optical system. The light source device 12 and the movable device 13 are driven and controlled by the control device 11 . The reflected light reflected by the target object 702 is detected by a photodetector 709. That is, the reflected light is received by an imaging device 707 via a condensing lens 706 or the like, which is an incident light detecting and receiving optical system, and the imaging device 707 outputs a detection signal to a signal processing circuit 708 . The signal processing circuit 708 performs predetermined processing such as binarization and noise processing on the input detection signal and outputs the result to the distance measurement circuit 710 .

FIG. 11 is a diagram showing a configuration example of a laser light source that is the light source device 12. As shown in FIG. The laser light source, which is the light source device 12, is formed of, for example, a VCSEL array 12A in which a plurality of laser element groups called "layers" are arranged in the same plane (surface emitting laser array). In the following description, the "surface emitting laser element" forming each layer of the laser light source, which is the light source device 12, is abbreviated as "light emitting element". The VCSEL array 12A has layers 121-1 to 121-m, and each layer 121 has a plurality of light emitting elements 1221 to 122n (hereinafter collectively referred to as "light emitting elements 122").

The light emitting elements 122 are elements that can be integrated on the same substrate, and the optical axis of each light emitting element 122 is orthogonal to the arrangement surface of the VCSEL array 12A.

The light emission timing of each layer 121 is independently controlled by the light source device driver 25. Also, each layer 121 is controlled so that the plurality of light emitting elements 122 included in the layer 121 simultaneously emit light.

Although a plurality of layers 121 are arranged one-dimensionally in FIG. 11, a VCSEL array 12A in which a plurality of layers 121 are arranged two-dimensionally may be used. The light emitting elements 122 of each layer 121 are arranged in a dense arrangement or in a honeycomb pattern at a predetermined pitch, but the arrangement is not limited to this example. The shape of the opening of the light emitting element 122 is not limited to a hexagon either. The number of layers 121 of the VCSEL array 12A, the number of light-emitting elements 122 in the layer 121, the size of the light-emitting region, etc. are appropriately designed according to the angular resolution, scanning range, detection distance, etc. required for the lidar device 700. .

The distance measuring circuit 710 detects the target object based on the time difference between the timing at which the light source device 12 emits laser light and the timing at which the photodetector 709 receives the laser light, or the phase difference for each pixel of the image sensor 707 that receives the light. The presence or absence of the object 702 is recognized, and distance information to the target object 702 is calculated.

Since the movable device 13 having the reflecting surface 14 is less likely to be damaged than a polygonal mirror and is small, it is possible to provide a compact radar device with high durability. Such a lidar device is attached to, for example, a vehicle, an aircraft, a ship, a robot, or the like, and can recognize the presence or absence of an obstacle and the distance to the obstacle by optically scanning a predetermined range.

FIG. 9 is a schematic diagram of an automobile 701, which is a moving object on which a lidar device 700 is mounted. The lidar device 700 is attached above the windshield of the automobile 701, on the ceiling of the front seat, or the like. The lidar device 700 recognizes the target object 702 by optically scanning, for example, in the traveling direction of the automobile 701 and receiving reflected light from the target object 702 existing in the traveling direction. The light projection unit of the lidar device 700 performs optical scanning while suppressing the divergence angle of the laser light in advance with an optical element such as an MLA, thereby reducing light loss in the scanning unit such as the movable device 13 and increasing the angle. A laser beam can be projected over a long distance with high resolution.

The mounting position of the rider device 700 is not limited to the upper front portion of the automobile 701, and may be mounted on the side surface or the rear portion. The lidar device 700 can be applied not only to vehicles but also to arbitrary moving bodies such as aircraft, flying bodies such as drones, and autonomous moving bodies such as robots. By adopting the configuration of the light projecting unit 1 of the embodiment, it is possible to detect the presence and position of an object over a wide range.

In the above object recognition device, the lidar device 700 has been described as an example. Any device may be used as long as it recognizes the target object 702 by receiving reflected light, and is not limited to the above-described embodiments.

For example, biometric authentication that recognizes an object by calculating object information such as shape from distance information obtained by optically scanning the hand or face, recording and referring to it, or recognizing an intruder by optically scanning the target range. The present invention can also be applied to a security sensor, a component of a three-dimensional scanner that calculates and recognizes object information such as shape from distance information obtained by optical scanning, and outputs it as three-dimensional data.

[Laser headlamp]
Next, a laser headlamp 50 in which the movable device of the present embodiment is applied to an automobile headlight will be described with reference to FIG. 12 . FIG. 12 is a schematic diagram illustrating an example of the configuration of the laser headlamp 50. As shown in FIG.

The laser headlamp 50 has a control device 11 , a light source device 12 b , a movable device 13 having a reflecting surface 14 , a mirror 51 and a transparent plate 52 .

The light source device 12b is a light source that emits blue laser light. Light emitted from the light source device 12 b enters the movable device 13 and is reflected by the reflecting surface 14 . The movable device 13 moves the reflecting surface in the XY directions based on a signal from the control device 11, and two-dimensionally scans the blue laser light from the light source device 12b in the XY directions.

The scanning light from the movable device 13 is reflected by the mirror 51 and enters the transparent plate 52 . The transparent plate 52 is coated with a yellow phosphor on its front or back surface. As the blue laser light from the mirror 51 passes through the yellow phosphor coating on the transparent plate 52, it changes to white within the legal headlight color range. As a result, the front of the automobile is illuminated with white light from the transparent plate 52 .

The scanning light from the movable device 13 is scattered in a predetermined manner when passing through the fluorescent material of the transparent plate 52 . This reduces the glare on the illuminated object in front of the vehicle.

When applying the movable device 13 to a headlight of a car, the colors of the light source device 12b and the phosphor are not limited to blue and yellow, respectively. For example, the light source device 12b may be near-ultraviolet rays, and the transparent plate 52 may be coated with a uniform mixture of the three primary colors of light, namely blue, green, and red phosphors. Even in this case, the light passing through the transparent plate 52 can be converted into white light, and the front of the automobile can be illuminated with white light.

[Head-mounted display]
Next, a head mounted display 60 to which the movable device of the present embodiment is applied will be described with reference to FIGS. 13 and 14. FIG. Here, the head-mounted display 60 is a head-mounted display that can be worn on a person's head, and can have a shape similar to eyeglasses, for example. The head-mounted display will hereinafter be abbreviated as HMD.

FIG. 13 is a perspective view illustrating the appearance of the HMD 60. In FIG. 13, the HMD 60 is composed of a front 60a and a temple 60b, which are provided approximately symmetrically in pairs on the left and right sides. The front 60a can be composed of, for example, a light guide plate 61, and the optical system, control device, and the like can be incorporated in the temple 60b.

FIG. 14 is a diagram partially illustrating the configuration of the HMD 60. Although FIG. 14 illustrates the configuration for the left eye, the HMD 60 has the same configuration for the right eye.

The HMD 60 has a control device 11 , a light source unit 530 , a light quantity adjusting section 507 , a movable device 13 having a reflecting surface 14 , a light guide plate 61 and a half mirror 62 .

The light source unit 530 unitizes the laser light sources 501R, 501G, and 501B, the collimating lenses 502, 503, and 504, and the dichroic mirrors 505 and 506 with an optical housing, as described above. In the light source unit 530, the three-color laser beams from the laser light sources 501R, 501G, and 501B are synthesized by dichroic mirrors 505 and 506 serving as synthesizing units. Combined parallel light is emitted from the light source unit 530 .

The light from the light source unit 530 is incident on the movable device 13 after the light amount is adjusted by the light amount adjusting section 507 . The movable device 13 moves the reflecting surface 14 in the XY directions based on a signal from the control device 11 and two-dimensionally scans the light from the light source unit 530 . The driving control of the movable device 13 is performed in synchronization with the light emission timing of the laser light sources 501R, 501G, and 501B, and a color image is formed by scanning light.

The scanning light from the movable device 13 is incident on the light guide plate 61 . The light guide plate 61 guides the scanning light to the half mirror 62 while reflecting it on the inner wall surface. The light guide plate 61 is made of resin or the like that is transparent to the wavelength of the scanning light.

The half mirror 62 reflects the light from the light guide plate 61 toward the back side of the HMD 60 and emits the light toward the eyes of the wearer 63 of the HMD 60 . The half mirror 62 has, for example, a free curved surface shape. An image of the scanning light is reflected by the half mirror 62 and formed on the retina of the wearer 63 . Alternatively, an image is formed on the retina of the wearer 63 by the reflection on the half mirror 62 and the lens effect of the crystalline lens in the eyeball. Further, the spatial distortion of the image is corrected by the reflection on the half mirror 62 . The wearer 63 can observe an image formed by light scanned in the XY directions.

Since 62 is a half mirror, the wearer 63 observes an image of light from the outside and an image of scanning light superimposed. By providing a mirror in place of the half mirror 62, the light from the outside may be eliminated and only the image by the scanning light may be observed.

[Packaging]
Next, the packaging of the movable device of this embodiment will be described with reference to FIG. 15 .

FIG. 15 is a schematic diagram of an example of a packaged mobile device.

As shown in FIG. 15, the movable device 13 is attached to an attachment member 802 arranged inside a package member 801, and a part of the package member 801 is covered with a transparent member 803 to be sealed. be done. Furthermore, the inside of the package is sealed with an inert gas such as nitrogen. As a result, deterioration due to oxidation of the movable device 13 is suppressed, and durability against environmental changes such as temperature is improved.

Details of the movable device of the present embodiment used in the optical deflection system, the optical scanning system, the image projection device, the optical writing device, the object recognition device, the laser headlamp, and the head mounted display described above are shown in the drawings below. will be described with reference to. In addition, in each drawing, the same components are given the same reference numerals, and duplicate explanations may be omitted.

In the description of the embodiments, sub-scanning is optical scanning with the first axis as the center of rotation, and main scanning is optical scanning with the second axis as the center of rotation. Further, in the terms of the embodiment, rotation, swinging, and movable are synonymous. Furthermore, among the directions indicated by the arrows, the X direction is the direction parallel to the first axis, the Y direction is the direction parallel to the second axis, and the Z direction is the direction perpendicular to the XY plane. Note that the Z direction is an example of a "layering direction".

[First Embodiment]
An optical deflector in the first embodiment will be described with reference to FIG. The optical deflector 201 in this embodiment has a movable device 13 , a drive circuit 221 , a displacement detection section 222 , a temperature detection section 223 , an amplitude detection section 224 , a frequency detection section 225 and a calculation section 226 . Note that the drive circuit 221 may be referred to as a drive signal generation unit because it generates a drive signal for driving the piezoelectric actuator 103 .

FIG. 17 shows the structure of the movable device 13 in this embodiment. The movable device 13 in this embodiment includes a mirror portion 101 that has a reflecting surface 14 that reflects light and is movable, a spring portion 102 that is a torsion bar, a piezoelectric actuator 103 that generates a driving force, and a piezoelectric actuator 103 that detects torsion of the spring portion 102 . It has a sensor 104, a frame-like fixing portion 105, and the like. The piezoelectric actuator 103 and the piezoelectric sensor 104 are provided on the surface of the cantilever portion 106, and the piezoelectric actuator 103 and the piezoelectric sensor 104 are arranged in parallel. In the present application, the mirror section 101 may be referred to as a reflecting section.

More specifically, spring portions 102 connected to the mirror portion 101 are provided in the -X direction and +X direction on both sides of the mirror portion 101, respectively. Each spring portion 102 is elongated in the X direction, one end of each spring portion 102 is connected to the mirror portion 101, and the other end is connected to the cantilever portion 106. there is Each cantilever portion 106 is elongated in the Y direction, and the other end of the spring portion 102 is connected to the central portion of the cantilever portion 106 . The cantilever portion 106 is connected to the frame-shaped fixing portion 105 at both ends in the Y direction.

Therefore, the mirror section 101 is supported by the support section 107 formed by the spring section 102 and the cantilever section 106 . In this embodiment, by applying a voltage to the piezoelectric actuator 103 provided on the surface of the cantilever portion 106, the cantilever portion 106 vibrates. It rotates around the first shaft, which is the driving shaft.

That is, in the movable device 13 according to the present embodiment, it is possible to receive the drive signal input from the drive circuit 221 and swing the mirror section 101 . Here, the drive signal is a sine wave, and by setting the frequency of the drive signal to a frequency close to the natural resonance frequency f0 of the spring portion 102 of the movable device 13, the deflection angle of the mirror portion 101 of the movable device 13 is increased. can do. In the present application, the swing angle may be referred to as the swing angle.

Therefore, when the force is generated in the piezoelectric actuator 103 by the drive signal input from the drive circuit 221 and the spring portion 102 is deformed, the piezoelectric sensor 104 outputs a detection signal. The detection signal is a signal that indicates the deflection angle of the mirror section 101 . The displacement amount detection section 222 detects the signal strength of this detection signal. At this time, when the signal strength of the detection signal is strong, it represents a state in which the deflection angle of the mirror section 101 is large, and when it is weak, it represents a state in which the deflection angle of the mirror section 101 is small.

Also, the temperature detection unit 223 is arranged near the movable device 13 and detects the ambient temperature of the piezoelectric actuator 103 in the movable device 13 . The amplitude detection unit 224 detects the drive amplitude of the drive signal input to the piezoelectric actuator 103. The frequency detection unit 225 detects the drive frequency of the drive signal input to the piezoelectric actuator 103.

The calculation unit 226 calculates the ambient temperature (T), which is the temperature information detected by the temperature detection unit 223, the amplitude detection unit 224, and the frequency detection unit 225, the drive amplitude (A), which is drive amplitude information, and the drive frequency, which is drive frequency information. An appropriate correction coefficient c(T, A, f) is calculated from (f). Furthermore, the output of the displacement amount detection unit 222 is multiplied by the correction coefficient c(T, A, f). As a result, the error between the output signal of the piezoelectric sensor 104 and the actual deflection angle of the mirror section 101 is corrected and output as deflection angle information. In this embodiment, by including the drive frequency detected by the frequency detection unit 225, more accurate correction can be performed. The correction coefficient c(T, A, f) is calculated using polynomials of linear functions of temperature (T), driving amplitude (A), and driving frequency (f), as shown in Equation 1 below. It may be calculated, but is not necessarily limited to this. For example, it may be calculated by calculation using non-linear functions of ambient temperature (T), driving amplitude (A), and driving frequency (f). Note that a0, a1 and a2 are coefficients and a3 is a constant.

固定部１０５は、図１７に示されるように、枠状に一体で形成されたものであってもよいが、図１８に示されるように、固定部１０５の一部に開口部１０５ａを設けることにより、固定部１０５が分離されているものであってもよい。ミラー部１０１が設けられている部分において、第１軸に対して直交する方向、即ち、±Ｙ方向に、開口部１０５ａを設けることにより、ミラー部１０１において反射された光が、枠状の固定部１０５により遮断されることを防ぐことができる。

The fixed part 105 may be formed integrally in a frame shape as shown in FIG. 17, but as shown in FIG. The fixing portion 105 may be separated by In the portion where the mirror section 101 is provided, openings 105a are provided in the directions perpendicular to the first axis, that is, in the ±Y directions. Blocking by the unit 105 can be prevented.

Furthermore, as shown in FIG. 19, in the movable device, the support portion 108 that supports the mirror portion 101 may have a folded spring structure in which a plurality of cantilever portions 109 are formed in a meandering shape. Each cantilever portion 109 is elongated in the Y direction, and a piezoelectric actuator 103 and a piezoelectric sensor 104 are provided on the surface of each cantilever portion 109 . Further, the connection position between the mirror portion 101 and the support portion 108 of the folded spring structure and the connection position between the support portion 108 and the fixed portion 105 are not limited to the positions shown in FIG. 19, and may be other positions. may

FIG. 20 shows a movable device shown in FIG. 19 having a structure in which the fixed portion 105 is provided with an opening 105a and the fixed portion 105 is separated, as in the case of FIG.

Next, the deflection angle of the mirror section 101 of the optical deflector and the maximum value of the output of the piezoelectric sensor 104 in this embodiment will be described.

FIG. 21 shows the frequency characteristics (mirror deflection angle characteristics) of the mirror deflection angle of the mirror section 101 in the vicinity of the resonance frequency f0 of the movable device 13 and the piezoelectric sensor detected by the displacement amount detection section 222 in the optical deflector according to the present embodiment. 104 output frequency characteristics (detection signal characteristics). Each signal is normalized by the value at the resonance frequency f0.

The deflection angle of the mirror section 101 and the detection output of the piezoelectric sensor 104 are preferably in a proportional relationship, and the mirror deflection angle characteristic and the detection signal characteristic preferably overlap without being affected by the frequency. However, when actually measured, as shown in FIG. 21, a deviation occurs between the mirror deflection angle characteristic and the detection signal characteristic. One possible cause of this is that the drive signal supplied to the piezoelectric actuator 103 and the parasitic resistance and parasitic capacitance in the output signal from the piezoelectric sensor 104 cause signal attenuation on the high frequency side. Therefore, in such a state, even if the deflection angle of the mirror section 101 is the same, the output of the piezoelectric sensor 104 shows different values depending on the frequency. can't

In the optical deflector according to the present embodiment, the frequency detection section 225 is provided, and the calculation section 226 performs correction including the frequency information obtained by the frequency detection section 225, so that the deflection angle of the mirror section 101 of the movable device 13 is can be obtained exactly. This makes it possible to accurately grasp the state of the optical deflector.

As described above, in the optical deflector according to the first embodiment, the mirror section 101 having the reflecting surface 14, the fixed section 105 around the mirror section 101, one end connected to the mirror section 101, and the other end connected to the fixed section 105 It is connected to the. A support portion 107 for supporting the mirror portion 101, etc., and a piezoelectric actuator 103 for swinging the mirror portion 101 with respect to the fixed portion 105 about a predetermined rotation axis by piezoelectric driving are provided. It has a piezoelectric sensor 104 that is arranged around the piezoelectric actuator 103 and serves as a detection unit that detects the amount of displacement of the piezoelectric actuator 103 , and a temperature detection unit 223 that measures the ambient temperature of the piezoelectric actuator 103 . It has an amplitude detection section 224 that detects the drive amplitude of the piezoelectric actuator drive signal and a frequency detection section 225 that detects the drive frequency of the piezoelectric actuator drive signal. It has a calculation unit 226 that calculates the deflection angle of the mirror unit 101 based on the displacement amount information, the temperature information, and the amplitude information and frequency information of the piezoelectric drive signal. Thus, in the optical deflector of this embodiment, the output signal of the piezoelectric sensor 104 can be corrected based on the correction coefficient calculated from the drive amplitude, drive frequency, and ambient temperature. Therefore, it is possible to accurately calculate the deflection angle of the mirror portion 101 of the optical deflector from the output of the piezoelectric sensor 104 and to accurately grasp the state of the optical deflector.

[Second embodiment]
Next, an optical deflector according to the second embodiment will be described with reference to FIG. The optical deflector 202 in this embodiment has a movable device 13 , a drive circuit 221 , a displacement amount detection section 222 , a temperature detection section 223 , a calculation section 226 , an amplitude information acquisition section 227 and a frequency information acquisition section 228 .

The amplitude information acquisition unit 227 acquires amplitude information of the drive signal generated by the drive circuit 221, that is, amplitude information from the drive circuit 221, and outputs a correction coefficient to the calculation unit 226 based on the information. Further, the frequency information acquisition unit 228 acquires frequency information of the drive signal generated by the drive circuit 221, that is, frequency information from the drive circuit 221, and outputs a correction coefficient to the calculation unit 226 based on the information.

Both the amplitude information acquisition section 227 and the frequency information acquisition section 228 do not need to detect values from the drive signal itself, and calculate correction coefficients by inputting respective set values from the drive circuit 221 . The calculation unit 226 calculates an appropriate correction coefficient based on the information input from the amplitude information acquisition unit 227, the frequency information acquisition unit 228, and the temperature detection unit 223, and multiplies the output of the displacement amount detection unit 222 by the calculated correction coefficient. This corrects the error between the output signal of the piezoelectric actuator 103 and the actual deflection angle of the mirror section 101 .

Note that the movable device 13, the displacement amount detection unit 222, and the temperature detection unit 223 in this embodiment are the same as those in the first embodiment.

As described above, the second embodiment includes a mirror portion 101 having a reflecting surface 14, one or two fixed portions 105 for supporting the mirror portion 101, and the mirror portion 101 at one end and the fixed portion 105 at the other end. and a connected support portion 107 . Further, the detector includes a piezoelectric actuator 103 that causes the mirror section 101 to oscillate about a predetermined axis with respect to the fixed section 105 by piezoelectric driving. and a piezoelectric sensor 104 that becomes It has a temperature detection unit 223 that measures the ambient temperature of the piezoelectric actuator 103 , an amplitude information acquisition unit 227 that acquires amplitude information from the drive circuit 221 , and a frequency information acquisition unit 228 that acquires frequency information from the drive circuit 221 . It has a calculation unit 226 that calculates the deflection angle of the mirror unit 101 based on the displacement amount information, the temperature information, and the amplitude information and frequency information of the piezoelectric drive signal. Thus, in the optical deflector of this embodiment, the output signal of the piezoelectric sensor 104 can be corrected based on the correction coefficient calculated from the amplitude and frequency of the driving signal and the ambient temperature. Therefore, even if there is an influence of the driving frequency, it is possible to accurately calculate the deflection angle of the mirror section 101 from the output of the piezoelectric sensor 104 and obtain the state of the optical deflector 202 more accurately. In this embodiment, the amplitude and frequency information of the drive signal is not detected from the drive signal itself, but is acquired from the setting information, so correction can be performed with high accuracy using a simple circuit.

[Third Embodiment]
Next, the optical deflector 203 according to the third embodiment will be explained with reference to FIG. The optical deflector 203 in this embodiment includes the movable device 13, the drive circuit 221, the displacement amount detection section 222, the temperature detection section 223, the amplitude detection section 224, the frequency detection section 225, the calculation section 226, and the drive amplitude control section 229. have.

The drive amplitude control unit 229 compares the externally input deflection angle setting value of the mirror unit 101 with the maximum deflection angle obtained from the deflection angle information of the mirror unit 101 calculated by the calculation unit 226 . Then, the amplitude of the driving circuit 221 is changed so that the deflection angle of the mirror section 101 becomes equal to the mirror deflection angle set value, thereby controlling the deflection angle of the mirror section 101 . Methods such as PID (Proportional-Integral-Differential) control are generally known for control. PID control is a method of controlling an input value based on three elements: the deviation between an output value and a target value, its integration, and differentiation.

Note that the operations of the movable device 13, the displacement amount detection unit 222, the temperature detection unit 223, the amplitude detection unit 224, the frequency detection unit 225, and the calculation unit 226 in this embodiment are the same as in the first embodiment.

As described above, the third embodiment has the mirror section 101 having the reflecting surface 14 and one or two fixing sections 105 that support the mirror section 101 . A piezoelectric actuator 103 is provided which has one end connected to the mirror portion 101 and the other end connected to the fixed portion 105, and which causes the mirror portion 101 to oscillate about a predetermined axis with respect to the fixed portion 105 by piezoelectric driving. It has a drive circuit 221 that inputs a drive signal to the piezoelectric actuator 103, a drive amplitude controller 229 that sets the drive amplitude of the drive circuit 221, and a piezoelectric sensor 104 that serves as a detector that detects the amount of displacement of the piezoelectric actuator 103. . It has a temperature detection unit 223 that measures the ambient temperature of the piezoelectric actuator 103, an amplitude detection unit 224 that detects the drive amplitude of the piezoelectric actuator drive signal, and a frequency detection unit 225 that detects the drive frequency of the piezoelectric actuator drive signal. It has a calculation unit 226 that calculates the deflection angle of the mirror unit 101 based on the displacement amount information, the temperature information, and the amplitude information and frequency information of the piezoelectric drive signal. With such a configuration, the output signal of the piezoelectric sensor 104 can be corrected based on the correction coefficient calculated from the drive amplitude, drive frequency, and ambient temperature. Therefore, even if there is an influence of the drive frequency, the deflection angle of the mirror section 101 of the optical deflector is accurately calculated from the output of the piezoelectric sensor 104, and the deflection angle of the mirror section 101 is calculated based on the calculated deflection angle. A desired swing angle can be controlled.

[Fourth Embodiment]
Next, the optical deflector 204 according to the fourth embodiment will be explained with reference to FIG. The optical deflector 204 in this embodiment includes the movable device 13, the drive circuit 221, the displacement amount detection unit 222, the temperature detection unit 223, the calculation unit 226, the amplitude information acquisition unit 227, the frequency information acquisition unit 228, and the drive amplitude control unit 229. have.

The drive amplitude control unit 229 compares the externally input deflection angle setting value of the mirror unit 101 with the maximum deflection angle obtained from the deflection angle information of the mirror unit 101 calculated by the calculation unit 226 . Then, the amplitude of the driving circuit 221 is changed so that the deflection angle of the mirror section 101 becomes equal to the mirror deflection angle set value, thereby controlling the deflection angle of the mirror section 101 . Methods such as PID control are generally known for control.

As described above, the fourth embodiment has the mirror section 101 having the reflecting surface 14 and one or two fixing sections 105 that support the mirror section 101 . A piezoelectric actuator 103 is provided which has one end connected to the mirror portion 101 and the other end connected to the fixed portion 105, and which causes the mirror portion 101 to oscillate about a predetermined axis with respect to the fixed portion 105 by piezoelectric driving. A drive circuit 221 for inputting a drive signal to the piezoelectric actuator 103, a drive amplitude controller 229 for setting the drive amplitude of the drive circuit 221, and a displacement amount arranged around the piezoelectric actuator 103 for detecting the displacement amount of the piezoelectric actuator 103. and a detection unit 222 . It has a temperature detection unit 223 that measures the ambient temperature of the piezoelectric actuator 103 , an amplitude information acquisition unit 227 that acquires amplitude information from the drive circuit 221 , and a frequency information acquisition unit 228 that acquires frequency information from the drive circuit 221 . It has a calculation unit 226 that calculates the deflection angle of the mirror unit 101 based on the displacement amount information, the temperature information, the amplitude information, and the frequency information. With such a configuration, the output signal of the piezoelectric sensor 104 can be corrected based on the correction coefficient calculated from the amplitude, frequency, and ambient temperature. As a result, the deflection angle of the mirror section 101 of the optical deflector is accurately calculated from the output of the piezoelectric sensor 104 even if there is an influence of the drive frequency, and the deflection angle of the mirror section 101 is calculated based on the calculated deflection angle. can be controlled to be a desired deflection angle. In this embodiment, the amplitude and frequency information of the drive signal can be obtained from the setting information without detecting the drive signal itself, so correction can be performed with high accuracy using a simple circuit.

Contents other than the above are the same as those of the second embodiment.

[Fifth Embodiment]
Next, a fifth embodiment will be described. This embodiment is a movable device applicable to the optical deflector in the first to fourth embodiments. Specifically, as shown in FIG. 25, the movable device 300 in the present embodiment is a movable device of a double-supported type (both ends supported beam) capable of rotating around the first axis and the second axis.

As shown in FIG. 25 , the movable device 300 has a movable portion 110 , first drive beams 120 a and 120 b , a fixed portion 140 and electrode terminals 150 . The movable portion 110 also has a reflecting portion 112 including the reflecting surface 14, a support portion 113, torsion bars 115a and 115b, and second drive beams 116a and 116b.

The reflective portion 112 is formed of a silicon layer or the like. However, the material is not limited to this, and may be composed of an oxide material, an inorganic material, an organic material, or the like. The reflective surface 14 is formed on the positive Z-direction surface of the reflective portion 112 . The reflective surface 14 is formed in a circular shape using a metal thin film containing aluminum, gold, silver, or the like, or a multi-layered film thereof.

A rib (not shown) for reinforcing the reflecting portion 112 is provided on the negative Z-direction surface of the reflecting portion 112 . The ribs are formed of a silicon support layer, a silicon oxide layer, or the like, and by providing the ribs, deformation strain of the reflecting portion 112 and the reflecting surface 14 that occurs during movement is suppressed.

The torsion bars 115a and 115b extend in the Y direction and are formed so as to sandwich the reflecting portion 112 in the Y direction. One end of the torsion bar 115 a is connected to the reflecting portion 112 and one end of the torsion bar 115 b is connected to the reflecting portion 112 . The reflector 112 is supported by torsion bars 115a and 115b.

The other end of the torsion bar 115a is connected to the second drive beam 116a, and the other end of the torsion bar 115b is connected to the second drive beam 116b. The second drive beams 116a and 116b, which are elastic beams, are provided with piezoelectric portions on the surfaces in the positive Z direction. When a drive voltage is applied from the electrode terminal 150 to the second drive beam 116a through an electric wire (not shown) laid out, the second drive beam 116a bends and deforms to twist the torsion bar 115a.

Similarly, when the second drive beam 116b is applied with a drive voltage through an electric wire (not shown) laid out from the electrode terminal 150, the second drive beam 116b bends and deforms to twist the torsion bar 115b.

Such twisting of the torsion bars 115a and 115b serves as a turning force, and the reflecting portion 112 turns around the second axis.

On the other hand, the supporting portion 113 is formed so as to surround the reflecting portion 112, the torsion bars 115a and 115b, and the second driving beams 116a and 116b from all sides. The support portion 113 is connected to the second drive beams 116a and 116b to support and restrain the second drive beams 116a and 116b. The support portion 113 indirectly supports the reflection portion 112 and the torsion bars 115a and 115b via the second drive beams 116a and 116b.

A connecting portion 114a is formed at the lower left corner of the supporting portion 113 in the figure, and the supporting portion 113 is connected to the first driving beam 120a via the connecting portion 114a. The connection portion 114 a extends in the positive X direction from the connection point with the first drive beam 120 a to connect the first drive beam 120 a and the support portion 113 .

A connection portion 114b is formed at the upper right corner of the support portion 113 in the figure, and the support portion 113 is connected to the first drive beam 120b via the connection portion 114b. The connection portion 114 b extends in the negative X direction from the connection point with the first drive beam 120 b to connect the first drive beam 120 b and the support portion 113 .

The first drive beam 120a and the first drive beam 120b sandwich and support the support portion 113 from both sides in the X direction.

The first drive beam 120a has a plurality of folded portions and connecting portions, and includes a meandering structure in which a plurality of elastic beams are connected. Piezoelectric portions are provided on the positive Z-direction surfaces of the elastic beams formed by the folded portions. The end of the first drive beam 120a that is not connected to the connecting portion 114a is connected to a fixing portion 140, and the fixing portion 140 fixes (supports and constrains) the first drive beam 120a.

Similarly, the first drive beam 120b includes a meandering structure in which a plurality of elastic beams are connected, having a plurality of folded portions and connecting portions. Piezoelectric portions are provided on the positive Z-side surfaces of the elastic beams formed by the folded portions. The end of the first drive beam 120b that is not connected to the connection portion 114b is connected to a fixing portion 140, and the fixing portion 140 fixes (supports and constrains) the first drive beam 120b. The first drive beams 120a and 120b are an example of "a pair of drive beams."

As shown in FIG. 25, the fixed part 140 has a rectangular frame structure with four sides, and the four sides surround the movable part 110 and the first drive beams 120a and 120b from all sides. I'm in.

On the other hand, a driving voltage is applied to the piezoelectric portions provided on the first driving beams 120a and 120b through electrical wiring (not shown) laid out from the electrode terminals 150. As shown in FIG.

Here, among the plurality of elastic beams of the first drive beam 120a, the piezoelectric units provided on the even-numbered elastic beams counted from the one closest to the reflecting portion 112 are referred to as a piezoelectric drive unit group 130A. Also, among the plurality of elastic beams of the first drive beam 120b, the piezoelectric units provided on the odd-numbered elastic beams counted from the one closest to the reflecting portion 112 are similarly referred to as a piezoelectric drive unit group 130A. The piezoelectric driving section group 130A bends and deforms in the same direction when drive voltages are simultaneously applied to the piezoelectric sections. Using this deformation as a turning force, the movable portion 110 turns around the first axis.

Also, among the elastic beams of the first drive beam 120a, the piezoelectric units provided on the odd-numbered elastic beams counted from the one closest to the reflecting unit 112 are referred to as a piezoelectric drive unit group 130B. Among the elastic beams of the first drive beam 120b, the even-numbered elastic beams counted from the one closest to the reflecting portion 112 are similarly defined as the piezoelectric drive portion group 130B. The piezoelectric driving section group 130B bends and deforms in the same direction when drive voltages are simultaneously applied to the piezoelectric sections. Using this deformation as a turning force, the movable portion 110 turns around the first axis in a direction opposite to the turning by the piezoelectric driving portion group 130A.

In the first drive beams 120a and 120b, the plurality of piezoelectric sections of the piezoelectric drive section groups 130A and 130B are bent and deformed simultaneously, thereby accumulating the amount of rotation caused by the bending deformation, and the deflection angle of the movable section 110 about the first axis. can be increased. When the amount of rotation of the movable portion 110 by the piezoelectric driving portion group 130A when the voltage is applied is balanced with the amount of rotation of the movable portion 110 by the piezoelectric driving portion group 130B when the voltage is applied, the deflection angle is becomes zero.

Here, a semiconductor such as an SOI (Silicon On Insulator) substrate can be used for the substrate (wafer) forming the movable device 13 . Each component of the movable device 13 can be integrally formed by processing with a semiconductor manufacturing technology. The first drive beams 120a and 120b and the second drive beams 116a and 116b may be formed after molding the SOI substrate or during molding of the SOI substrate.

<Method of driving the movable device>
Next, an example of a method for driving the movable device 13 will be described with reference to FIG. 25 . For rotation about the second axis, a drive voltage is applied to the second drive beams 116a and 116b at the resonance frequency of the integrated structure comprising the reflector 112, the torsion bars 115a and 115b, and the second drive beams 116a and 116b. applied. The resonance frequency is, for example, 20 kHz.

The piezoelectric portion of the second driving beam 116a to which one end of the torsion bar 115a is connected deforms when a driving voltage is applied through the upper electrode and the lower electrode. Due to the deformation of the piezoelectric portion, the second drive beam 116a is bent and deformed, and the torsion bar 115a is twisted.

Similarly, the piezoelectric portion of the second drive beam 116b to which one end of the torsion bar 115b is connected deforms when a drive voltage is applied through the upper electrode and the lower electrode. Due to the deformation of the piezoelectric portion, the second drive beam 116b is bent and deformed, and the torsion bar 115b is twisted.

The torsion of the torsion bars 115a and 115b acts as a turning force, and the reflecting portion 112 reciprocates around the second axis. The waveform of the drive voltage applied to the second drive beams 116a and 116b is a sine wave or the like. The reflecting portion 112 is resonatingly driven and reciprocatingly rotated at the cycle of the sinusoidal drive voltage waveform.

In the rotation about the first axis, the waveform of the driving voltage applied to the piezoelectric actuator group 130A includes, for example, a sawtooth waveform. Further, the frequency of the driving voltage is 60 Hz or the like. Assuming that the time width of the rising period during which the voltage value increases from the minimum value to the next maximum value is Tr, and the time width of the falling period during which the voltage value decreases from the maximum value to the next minimum value is Tf, the waveform of the drive voltage is: For example, a ratio of Tr:Tf=9:1 is set in advance. At this time, the ratio of Tr to one cycle is called the symmetry of the drive voltage.

The waveform of the driving voltage applied to the piezoelectric driving section group 130B similarly includes a waveform such as a sawtooth waveform. Further, the frequency of the driving voltage is 60 Hz or the like. For the waveform of the drive voltage, for example, a ratio of Tf:Tr=9:1 is set in advance.

Further, the period of the waveform of the driving voltage applied to the piezoelectric driving section group 130A and the period of the waveform of the driving voltage applied to the piezoelectric driving section group 130B are set to be the same.

The sawtooth waveform of the drive voltage is produced by superposition of sine waves. Here, in this embodiment, an example of using a sawtooth waveform as the waveform of the driving voltage is shown, but the present invention is not limited to this. The waveform may be changed according to the device characteristics of the movable device, such as a drive voltage having a saw-tooth waveform with rounded apexes or a saw-tooth waveform with a linear region curved.

The operation of the first drive beams 120a and 120b when the drive voltage is applied is as described above, and the bending deformation of the piezoelectric drive section groups 130A and 130B causes the movable section 110 to reciprocate around the first axis.

<Cross-sectional shape of the movable device>
Next, the cross-sectional shape of the movable device 13 will be described with reference to FIG. 26 . 26 is a cross-sectional view taken along the first axis in FIG. 25. FIG.

FIG. 26 shows cross-sectional structures of the first drive beams 120a and 120b, the movable portion 110, and the fixed portion 140. As shown in FIG.

The first drive beams 120a and 120b have a silicon layer 303 and piezoelectric drive unit groups 130A and 130B formed on the surface of the silicon layer 303 on the positive Z direction side.

The silicon layer 303 is an elastic body that deforms according to the deformation of the piezoelectric actuator groups 130A and 130B, and is composed of a silicon layer of an SOI substrate.

The piezoelectric actuator groups 130A and 130B include a lower electrode 311, a piezoelectric material 312, and an upper electrode 313, which are sequentially formed on the surface of the silicon layer 303 in the positive Z direction. The lower electrode 311 and the upper electrode 313 are composed of metal thin films such as gold (Au) or platinum (Pt), and the piezoelectric material 312 is composed of a piezoelectric material such as PZT (lead zirconate titanate).

Each of the piezoelectric drive units included in the piezoelectric drive unit groups 130A and 130B has the same layer structure as above. The piezoelectric actuator groups 130A and 130B may be covered with an insulating layer such as SiO ₂ (silicon oxide), and electrical wiring may be provided in the positive Z direction.

Next, the movable part 110 includes a support layer 351, an interlayer film 352 laminated on the positive Z-direction surface of the support layer 351, and a movable layer 353 laminated on the positive Z-direction surface of the interlayer film 352. have.

The support layer 351 is composed of single-crystal silicon of an SOI substrate, an inorganic material, an organic material, or the like, and the interlayer film 352 is composed of silicon oxide or the like. The movable layer 353 is an elastic body that deforms according to the deformation of the second drive beams 116a and 116b, and is composed of a silicon layer of an SOI substrate or the like. Here, as shown in FIG. 26, the supporting layer 351 includes a reflecting surface supporting layer 351a on the negative Z direction side of the reflecting surface 14 and a supporting portion supporting layer 351b on the negative Z direction side of the supporting portion 113. and are included.

Next, the fixing part 140 includes a fixing support layer 361, an interlayer film 362 laminated on the positive Z-direction surface of the fixing support layer 361, and a silicon layer laminated on the positive Z-direction surface of the interlayer film 362. 363.

The fixed support layer 361 is composed of single crystal silicon of the SOI substrate, inorganic material, organic material, or the like, and the interlayer film 362 is composed of silicon oxide or the like. The silicon layer 363 is composed of the silicon layer of the SOI substrate.

The silicon layers 303 and 363 and the movable layer 353 are not limited to the silicon layers of the SOI substrate, and may be made of an oxidizing agent, an inorganic material, an organic material, or the like. Also, the support layer 351 and the fixed support layer 361 may be made of an inorganic material, an organic material, or the like.

By the way, the second drive beams 116a and 116b (see FIG. 25) in the movable part 110 have a beam-shaped member, and an upper electrode, a piezoelectric member, and a lower electrode on the beam-shaped member. The electrodes are covered with an insulating layer. Also, the insulating layer expands and contracts together with the piezoelectric member when the drive beam is driven.

Furthermore, the central portion of the second drive beam 116a is connected to the torsion bar 115a, both ends of the second drive beam 116a are connected to the movable frame (support portion 113), and at least one of the upper electrode and the lower electrode is connected. The corner of the tip of the second drive beam 116a on the one end side of the electrode is chamfered (for example, arc-shaped or tapered).

Similarly, the central portion of the second drive beam 116b is connected to the torsion bar 115b, both ends of the second drive beam 116b are connected to the movable frame (support portion 113), and at least the upper electrode and the lower electrode are connected. The tip of one end of the second drive beam 116b of one electrode has a chamfered shape (for example, an arc shape or a tapered shape).

In this embodiment, the second drive beams 116a and 116b have a double-supported beam structure in which both ends are connected to the support portion 113. However, as shown in FIG. 116a and 116b may be cantilever structures. In the cantilever structure, one end of the second drive beam 116a is connected to the support portion 113 and the other end is connected to the torsion bar 115a. One end of the second drive beam 116b is connected to the support portion 113, and the other end is connected to the torsion bar 115b.

In the case of the cantilever structure, at least one of the upper electrode and the lower electrode provided on the second drive beams 116a and 116b has an arc-shaped or tapered corner on the side connected to the torsion bar. formed in More preferably, both the upper electrode and the lower electrode are similarly arc-shaped or tapered.

With the above configuration, even if the dielectric strength is lowered due to the driving of the second drive beams 116a and 116b, creeping discharge can be suppressed, and the durability of the movable device 13 can be improved.

Although examples of embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and various modifications can be made within the scope of the invention described in the scope of the claims. Transformation and change are possible.

10 Optical scanning system 11 Control device 12, 12b Light source device 13, 13A, 13B, 13C, 13D, 13E, 13F Movable device 14 Reflecting surface 15 Surface to be scanned 25 Light source device driver 26 Movable device driver 30 Control unit 31 Drive signal output unit 50 laser headlamp 51 mirror 52 transparent plate 60 head mount display 60a front 60b temple 61 light guide plate 62 half mirror 63 wearer 101 mirror portion 102 spring portion 103 piezoelectric actuator 104 piezoelectric sensor 105 fixed portion 106 cantilever portion 107 support portions 201, 202 , 203, 204 Optical deflector 221 Drive circuit 222 Displacement detection unit 223 Temperature detection unit 224 Amplitude detection unit 225 Frequency detection unit 226 Operation unit 400 Automobile (an example of a vehicle)
500 head-up display device (an example of an image projection device, an example of a head-up display)
650 laser printer 700 lidar device (an example of an object recognition device)
702 target object 801 package member 802 attachment member 803 transparent member

Japanese Patent No. 5400636

Claims (13)

a reflecting portion having a reflecting surface that reflects light;
a supporting portion connected at one end to the reflecting portion;
a fixing portion connected to the other end of the support portion;
a piezoelectric member that deforms the supporting portion to swing the reflecting portion;
a frequency detection unit that detects the frequency of the drive signal input to the piezoelectric member;
a piezoelectric sensor that outputs a detection signal corresponding to deformation of the support;
a displacement detection unit that detects the signal strength of the detection signal ;
has
A calculation unit for calculating a swing angle of the reflection unit based on at least frequency information of the frequency detected by the frequency detection unit and the signal intensity detected by the displacement amount detection unit. An optical deflector characterized by: an amplitude detection unit that detects the amplitude of the drive signal input to the piezoelectric member;
The computing unit is configured to at least match the frequency information of the frequency detected by the frequency detection unit, the signal intensity detected by the displacement amount detection unit, and the amplitude information of the amplitude detected by the amplitude detection unit. 2. The optical deflector according to claim 1, wherein the swing angle of said reflecting portion is calculated based on the above. a temperature detection unit that detects the ambient temperature of the piezoelectric member;
3. The optical deflector according to claim 1, wherein the calculating section further adds temperature information of the ambient temperature detected by the temperature detecting section to calculate the swing angle of the reflecting section. . a drive signal generator that generates a drive signal for driving the piezoelectric member;
3. The calculation unit according to claim 2, wherein the calculation unit calculates the swing angle of the reflection unit using the frequency and amplitude of the drive signal obtained from the drive signal generation unit as the amplitude information and the frequency information. optical deflector. a temperature detection unit that detects the ambient temperature of the piezoelectric member;
The calculation unit calculates a correction coefficient by calculation using a polynomial including temperature information of the ambient temperature detected by the temperature detection unit, the amplitude information, and the frequency information, and multiplies the signal strength by the correction coefficient. 5. The optical deflector according to claim 4, wherein the swing angle of said reflecting portion is calculated. a drive amplitude control unit that controls the drive signal input to the piezoelectric member from the drive signal generation unit based on the information on the swing angle;
6. The optical deflector according to claim 4, wherein the drive amplitude control section controls the oscillation angle of the reflection section caused by the piezoelectric member to be constant. an optical deflector according to any one of claims 1 to 6;
a light source that emits light;
with
An image projection device that deflects and projects light emitted from the light source. A plurality of the light sources are provided,
The plurality of light sources emit light of different wavelengths,
further comprising a synthesizing unit that synthesizes the plurality of lights emitted from the plurality of light sources;
8. The image projection apparatus according to claim 7, wherein the combined light in said combining unit is deflected and projected. A head-up display comprising the optical deflector according to any one of claims 1 to 6. A laser headlamp comprising the optical deflector according to any one of claims 1 to 6. A head mounted display comprising the optical deflector according to any one of claims 1 to 6. an optical deflector according to any one of claims 1 to 6;
a light source that emits light;
with
1. An object recognition apparatus that recognizes an object by deflecting light emitted from the light source, irradiating the light onto an object, and detecting reflected light reflected by the object. A vehicle comprising at least one of the head-up display according to claim 9, the laser headlamp according to claim 10, and the object recognition device according to claim 12.

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