JP7563091B2 - Optical deflector, deflection device, object recognition device, image projection device, and moving object - Google Patents

Description

The present invention relates to an optical deflector, a deflection device, an object recognition device, an image projection device, and a moving object.

In recent years, advances in micromachining technology that utilizes semiconductor manufacturing technology have led to the development of MEMS (Micro Electro Mechanical Systems) devices that are manufactured by microfabricating silicon or glass.

The MEMS device can be used, for example, as an optical deflector that uses a piezoelectric actuator to drive (rotate) a mirror section. The piezoelectric actuator has a structure in which, for example, a mirror section with a reflective surface, a torsion bar, and a beam section (elastic beam) are integrally formed on a wafer, and a thin film of piezoelectric material is laminated on the beam section.

As an example of such an optical deflector, an optical deflector capable of increasing the limit deflection angle of the mirror portion has been disclosed (for example, Patent Document 1).

The optical deflector described in Patent Document 1 has a circumferential rib and a protruding rib. However, in this optical deflector, the protruding rib is continuous with the circumferential rib of the frame part that forms the movable part, so the torsional deformation of the torsion bar is suppressed and the torsional resonance mode of the mirror part is inhibited. This makes it difficult to increase the amplitude (amplitude sensitivity) of the mirror part, and the desired wide angle of view cannot be achieved.

The present invention was made in consideration of the above points, and aims to expand the breaking limit angle of the optical deflector and achieve the desired wide angle of view.

An optical deflector according to one aspect of the disclosed technology has a mirror section that reflects light, a pair of support sections each having one end connected to the mirror section and supporting the mirror section, a pair of drive beams each connected to the other end of each of the support sections and deforming the support section to rotate the mirror section around a first axis, and a connection section that connects the support section and the drive beam, wherein the connection section is provided with a rib whose longitudinal direction intersects with the longitudinal direction of the pair of support sections, and when a plane parallel to the reflective surface of the mirror section when the pair of drive beams are not driven is divided in two by a straight line parallel to the longitudinal direction of the pair of support sections, the pair of drive beams are positioned on one of the two divided planes.

The disclosed technology makes it possible to expand the breaking limit angle of the optical deflector and achieve the desired wide angle of view.

FIG. 2 is a top view of the optical deflector according to the first embodiment. FIG. 2 is a rear view of the optical deflector according to the first embodiment. FIG. 11 is a correlation diagram between the rib length of the connection portion and the fracture amplitude at the connection portion. FIG. 4 is an explanatory diagram (1) of a connection rib of the optical deflector according to the first embodiment. FIG. 2 is an explanatory diagram (2) of a connection rib of the optical deflector according to the first embodiment. FIG. 11 is a top view of an optical deflector according to a second embodiment. FIG. 11 is a rear view of the optical deflector according to the second embodiment. FIG. 13 is a rear view of a modified example of the optical deflector in the second embodiment. FIG. 13 is a top view of an optical deflector according to a third embodiment. FIG. 13 is a rear view of the optical deflector according to the third embodiment. FIG. 13 is a rear view of a modified example of the optical deflector in the third embodiment. FIG. 13 is a top view of an optical deflector according to a fourth embodiment. 1 is a schematic diagram of an example optical scanning system. FIG. 2 is a diagram illustrating a hardware configuration of an example of an optical scanning system. FIG. 2 is a functional block diagram of an example of a drive device. 13 is a flowchart of an example of a process related to the optical scanning system. 1 is a schematic diagram of an example of an automobile equipped with a head-up display device. 1 is a schematic diagram of an example of a head-up display device. 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. 1 is a schematic diagram of an example of an automobile equipped with a laser radar device. FIG. 1 is a schematic diagram of an example of a laser radar device. FIG. 2 is a schematic diagram of an example of a packaged optical deflector.

Below, a description will be given of a mode for carrying out the invention with reference to the drawings. In each drawing, the same components are given the same reference numerals, and duplicated explanations may be omitted.

First Embodiment
2. Description of the Related Art In recent years, optical deflectors used in image forming apparatuses and the like are required to have a mirror portion with a larger amplitude and a higher resolution in order to improve the image quality of the image forming apparatuses and the like.

When the amplitude of the mirror part is increased, the rotational acceleration of the mirror part increases in proportion to the amplitude of the mirror part. In other words, as the amplitude of the mirror part increases, the stress on the torsion bar and fixed part that support the mirror part increases accordingly. When the stress on the torsion bar and fixed part increases and the amplitude of the mirror part reaches the mirror amplitude limit angle at which the torsion bar and fixed part are destroyed, the optical deflector is destroyed.

In addition, to increase the resolution of the mirror section, it is necessary to increase the number of scanning lines, which requires increasing the drive frequency (resonant frequency) of the mirror section. When the resonant frequency of the mirror section increases, the rotational acceleration of the mirror section increases in proportion to the square of the frequency. Therefore, even if the amplitude of the mirror section is the same, when the frequency of the mirror section increases, the load on the torsion bar and fixed section that support the mirror section increases rapidly. And when the load on the torsion bar and fixed section exceeds the breaking strength of the torsion bar and fixed section, the optical deflector is destroyed.

Furthermore, in conventional optical deflectors with a cantilever structure, the tip side of the drive beam is open at the connection with the drive beam (beam section) that supports the torsion bar in a cantilever manner. Therefore, when the frequency of the mirror section increases, the connection between the torsion bar and the drive beam is likely to become more deformed. This means that the connection between the torsion bar and the drive beam is likely to be unable to withstand the load caused by the torsion bar's twisting, and the optical deflector is likely to be destroyed.

The optical deflector in this embodiment has a rib structure at the connection that connects the torsion bar and the drive beam (beam portion). The rib structure suppresses deformation of the connection due to increased load associated with larger amplitude and higher frequency of the mirror portion, and relieves stress at the connection, thereby expanding the fracture limit angle of the optical deflector.

(Optical deflector)
An optical deflector according to a first embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a top view of the optical deflector according to this embodiment, and Fig. 2 is a rear view.

The optical deflector in this embodiment has a mirror section 110 having a reflective surface 14 that reflects light, and torsion bars 120 are connected to both sides of this mirror section 110. The torsion bar 120 is also called a torsion bar spring, but in this application it will be referred to as a torsion bar 120.

One end 120a of the torsion bar 120 is connected to the mirror section 110, and the other end 120b opposite to the one end 120a is connected to the drive beam 130 via a connection section 140. The drive beams 130 are disposed on both sides of the axial direction (i.e., the X-axis direction) of the torsion bar 120. In the present application, one end of the object may be referred to as one end, and the other end may be referred to as the other end.

The drive beam 130 has a structure in which a piezoelectric material 132 is laminated on a beam portion 131 of a base body formed from a silicon substrate or the like. The drive beam 130 has, for example, a flat rectangular unimorph structure. One end of the drive beam 130 is connected to a fixed frame 150, and the other end is connected to the other end 120b of the torsion bar 120 via a connection portion 140. In this application, the fixed frame 150 may be referred to as a frame portion.

In an optical deflector having such a structure, the drive beam 130 provided on one side of the first axis that serves as the rotation axis of the mirror section 110, i.e., the central axis of the pair of torsion bars 120, supports the mirror section 110 and the torsion bars 120. The drive beam 130 is located, for example, on the -Y side of the first axis. The optical deflector in this embodiment has a cantilever structure in which the drive beam 130 is cantilevered by the fixed frame 150.

In this embodiment, the direction of the torsion central axis of the torsion bar 120, i.e., the first axis of the mirror section 110, is the X-axis direction, the normal to the reflecting surface 14 of the mirror section 110 is the Z-axis direction, and the direction perpendicular to the X-axis direction and the Z-axis direction is the Y-axis direction. In addition, in a base body formed of a silicon substrate or the like, the connection portion where the torsion bar 120 and the drive beam 130 are connected is referred to as the connection portion 140.

In the optical deflector of this embodiment, a mirror rib 111 is provided on the back surface of the mirror section 110, and a connection rib 141 is provided on the back surface of the connection section 140. The connection rib 141 is formed to extend in a direction intersecting the first axis, which is the rotation axis, preferably in the Y-axis direction perpendicular to the first axis. Since the connection rib 141 formed on the back surface of the connection section 140 in this manner suppresses deformation in the connection section 140, the stress in the connection section 140 when the mirror section 110 rotates is reduced, and the fracture limit angle of the optical deflector can be increased. As a result, it becomes possible to rotate the mirror section 110 with a large amplitude.

Here, the connection line that is the boundary of the connection portion between the drive beam 130 and the connection portion 140 is an imaginary line K that runs from the end point of the fillet-shaped fixed end side fillet 142 closest to the drive beam 130 along the first axis direction. In this embodiment, the strength of the connection portion 140 against breakage can be increased by providing a connection portion rib 141 on this imaginary line K. The connection portion rib 141 is provided so as to straddle the imaginary line K that runs from the end of the fixed end side fillet 142 closest to the drive beam 130 along the first axis direction, which is the X-axis direction.

By providing the connection part 140 and the drive beam 130 with a connection part rib 141 extending in the Y-axis direction perpendicular to the first axis, deformation of the connection part 140 due to increased load associated with larger amplitude and higher frequency is suppressed, and stress in the connection part 140 is alleviated. This makes it possible to expand the fracture limit angle of the optical deflector.

In the optical deflector of this embodiment, the mirror section 110, the torsion bar 120, and the drive beam 130 are integrally formed by processing a silicon substrate using a MEMS process. The reflective surface 14 of the mirror section 110 is formed, for example, by depositing a thin film of a metal such as aluminum or silver on the surface of the silicon substrate.

The drive beam 130 has a cantilever structure that supports the torsion bar 120 and the mirror section 110 from one side, and the tip of the drive beam 130 on the +Y side is a free end. Therefore, the mirror section 110 can rotate with a large amplitude without being subjected to unnecessary constraints when rotating. This allows the force generated by bending the drive beam 130 to be efficiently transmitted to the deformation of the torsion bar 120 in the twisting direction.

The cantilever-structured optical deflector shown in Figures 1 and 2 can achieve sufficiently high drive sensitivity (amplitude angle relative to applied voltage) by appropriately designing the bending resonance of the drive beam 130 and the torsional resonance of the torsion bar 120. Therefore, in a cantilever-structured optical deflector, the achievable amplitude angle is limited by the fracture limit angle due to the strength of the silicon structure.

Since the strength limit (breaking stress) of the optical deflector is determined by the material (Si), it is necessary to optimize the structural design so that the stress generated during rotation is lower than the breaking stress. In the optical deflector of this embodiment, as described above, by providing a connection rib 141 on the back surface of the connection part 140, it is possible to suppress the stress generated in the connection part 140 when the mirror part 110 rotates and increase the breaking limit angle of the optical deflector.

In an optical deflector having a structure in which the connection rib 141 is not provided on the back surface of the connection portion 140, stress is concentrated at the fixed end fillet formed on the side where the drive beam is provided and at a specified location on the virtual line K. In contrast, in the optical deflector of this embodiment, the connection rib 141 is provided on the back surface of the connection portion 140, so that the stress generated at the fixed end fillet 142 formed on the side of the connection portion 140 where the drive beam 130 is provided and at a specified location on the virtual line K is alleviated.

Figure 3 shows the relationship between the fracture amplitude estimated from the stress generated in the connection part 140 obtained by the finite element simulation and the connection part rib length of the connection part rib 141 of the connection part 140. The fracture amplitude was calculated by experimentally determining the fracture stress and converting it from the stress obtained by the simulation. In addition, "Connection part rib length 0 μm" in Figure 3 means a state in which the connection part rib 141 is not provided. As shown in Figure 3, by providing the connection part rib 141 with a connection part rib length of 350 μm, the fracture strength can be increased and the fracture amplitude can be made about 30° or more. In this case, as shown in Figure 4, the connection part rib 141 extends further to the -Y side, which is the drive beam 130 side, than the end of the -Y side of the fixed end side fillet 142. In this way, by providing the connection part rib 141 to the drive beam 130 side from the fixed end side fillet 142, where the width in the X-axis direction is narrowest, in the connection part 140, the fracture amplitude can be increased. The five levels of parameters 85, 95, 105, 115, and 125 shown in FIG. 3 are design parameters related to the offset of the torsion bar 120 from the center of the mirror portion 110, and are parameters that optimize the balance of the cantilever structure. All five levels of parameters have the same tendency.

Next, the position where the connection rib 141 is formed will be described with reference to FIG. 5. The connection rib 141 is provided at the center 140a of the connection 140 in the X-axis direction, in the region opposite the torsion bar 120 when the connection 140 is divided into two regions along the Y-axis direction. In this way, by providing the connection rib 141 at a position away from the torsion bar 120, it is possible to suppress stress concentration that occurs when the torsional deformation of the torsion bar 120 is suddenly restrained by the connection rib 141. As a result, it is possible to increase the fracture limit angle of the optical deflector.

Furthermore, the connection rib 141 is provided a predetermined length inward from the +Y side end 140b and the -X side end 140c of the connection part 140. Specifically, the connection rib 141 is provided at a position Ya away from the -Y side, which is more inward than the +Y side end 140b of the connection part 140, and at a position Xa away from the +X side, which is more inward than the -X side end 140c. When a connection rib is provided at the end of the connection part, stress concentration may occur, but by providing the connection rib 141 inward from the end of the connection part 140, stress concentration can be suppressed.

Second Embodiment
Next, an optical deflector according to a second embodiment will be described with reference to Fig. 6 and Fig. 7. Fig. 6 is a top view of the optical deflector according to this embodiment, and Fig. 7 is a rear view.

In the optical deflector of this embodiment, a convex portion 143 is formed at the end of the connection portion 140 on the +Y side, which is the side opposite to the side connected to the drive beam 130, and a free end side fillet 144 is formed on the torsion bar 120 side of the convex portion 143. In addition, a fixed end side fillet 142 is provided on the connection portion 140 on the -Y side, which is the drive beam 130 side. Therefore, in the connection portion 140, a free end side fillet 144 and a fixed end side fillet 142 are provided on both sides of the torsion bar 120. The free end side fillet 144 is provided to suppress stress due to the twisting of the torsion bar 120. In this application, the free end side fillet 144 may be described as a first fillet portion, and the fixed end side fillet 142 may be described as a second fillet portion.

Furthermore, in the optical deflector of this embodiment, the connection rib 141 is also provided on the convex portion 143. That is, in this embodiment, the connection rib 141 is formed to extend further toward the +Y side than the end of the +Y side of the torsion bar 120. The connection rib 141 is formed to extend in a direction intersecting the first axis that is the rotation axis of the mirror part 110, that is, the central axis of the torsion bar 120, preferably in the Y-axis direction perpendicular to the first axis. This suppresses deformation in the connection part 140, thereby reducing the stress of the connection part 140 when the mirror part 110 rotates, and the fracture limit angle of the optical deflector can be increased, making it possible to rotate the mirror part 110 with a large amplitude.

In the optical deflector of this embodiment, the shape of the free end side fillet 144 may be formed by a circular arc. In addition, the curvature of the fillet shape of the fixed end side fillet 142 may be different from the curvature of the fillet shape of the free end side fillet 144. Specifically, the curvature of the fillet shape of the free end side fillet 144 may be formed to be smaller than the curvature of the fillet shape of the fixed end side fillet 142.

When the curvature of the arc forming the fillet shape in the fixed end fillet 142 is the same as the curvature of the arc forming the fillet shape in the free end fillet 144, the stress in the vicinity of the fixed end fillet 142 becomes large. By making the curvature of the fillet shape of the free end fillet 144 smaller than the curvature of the fillet shape of the fixed end fillet 142, the stress in the vicinity of the fixed end fillet 142 and the stress in the vicinity of the free end fillet 144 can be made equal.

The fillet shape of the free end fillet 144 may be formed as an elliptical arc. In this case, the major axis of the ellipse may be formed to be in the X-axis direction, i.e., the longitudinal direction of the torsion bar 120.

In addition, the fillet shape of the free end side fillet 144 may be formed by an arc with a predetermined radius of curvature, and the angle formed by the portion where the fillet shape of the free end side fillet 144 is formed may be 90 degrees or less.

By using this shape, the length of the convex portion 143 on the +Y side can be shortened, making the drive beam 130 lighter and increasing the resonant frequency, and preventing damage to the drive beam 130 due to bending.

The optical deflector shown in Figs. 6 and 7 is an optical deflector having a structure in which a free end fillet 144 is provided, but the optical deflector in this embodiment may be an optical deflector not having a free end fillet 144, as shown in Fig. 8. Even with an optical deflector having the structure shown in Fig. 8, the effect of providing the connection rib 141 up to the convex portion 143 can be obtained.

All other aspects are the same as in the first embodiment.

Third Embodiment
Next, an optical deflector according to a third embodiment will be described with reference to Fig. 9 and Fig. 10. Fig. 9 is a top view of the optical deflector according to this embodiment, and Fig. 10 is a rear view.

The optical deflector in this embodiment has a mirror section 110 with a reflective surface 14 that reflects light, and torsion bars 120 are connected to both sides of this mirror section 110.

One end 120a of the torsion bar 120 is connected to the mirror section 110, and the other end 120b opposite to the one end 120a is connected to the drive beam 230 via a connection section 240. The drive beams 230 are disposed on both sides of the torsion bar 120 in the axial direction (i.e., the X-axis direction).

In the optical deflector of this embodiment, the drive beams 230 support a pair of torsion bars 120 from both sides of the first axis, which is the central axis of the torsion bar 120. That is, as shown in FIG. 10, two drive beams 230 support each of the pair of torsion bars 120, and a total of four drive beams 230 are provided.

The drive beam 230 has a structure in which a piezoelectric material 232 is laminated on a beam portion 231 of a base body formed from a silicon substrate or the like. The drive beam 230 has, for example, a flat rectangular unimorph structure. One end of the drive beam 230 is connected to a fixed frame 250, and the other end is connected to the other end 120b of the torsion bar 120 via a connection portion 240. In this application, the fixed frame 250 may be referred to as a frame portion.

Therefore, the drive beams 230 are arranged on both sides of the central axis of the torsion bar 120 at the other end 120b of the torsion bar 120, and the mirror section 110 and the torsion bar 120 are supported at both ends by beam-shaped members relative to the fixed frame 250. In other words, the mirror section 110 and the torsion bar 120 are supported at both ends by the drive beam 230 on the +Y side and the drive beam 230 on the -Y side relative to the first axis.

As shown in Figures 9 and 10, a connection rib 241 is provided on the back surface of the connection portion 240 that connects the torsion bar 120 and the drive beam 230, extending in the Y-axis direction perpendicular to the first axis, which is the rotation axis. This suppresses deformation of the connection portion 240, reducing the stress on the connection portion 240 when the mirror portion 110 rotates, making it possible to increase the fracture limit angle of the optical deflector and rotate the mirror portion 110 with a large amplitude.

The connection rib 241 may be a single continuous rib as shown in FIG. 10, or may be a structure divided into two parts on either side of the central axis of the torsion bar 120 as shown in FIG. 11. As shown in FIG. 11, by dividing the connection rib 241 into two parts, the rigidity of the connection 240 is slightly reduced, so the resistance to destruction is reduced, but deformation due to the force of the drive beam 230 is more easily transmitted to the torsion bar 120, making it easier to obtain a large amplitude.

All other aspects are the same as in the first embodiment.

Fourth embodiment
Next, an optical deflector in the fourth embodiment will be described. The optical deflector in this embodiment can rotate around a first axis, which is a rotation axis, and a second axis perpendicular to the first axis. Specifically, as shown in FIG. 12, the mirror section 110, the torsion bar 120, the drive beam 130, the fixed end side fillet 142, and the free end side fillet 144 in the second embodiment are provided inside the sub-scanning movable frame 350. The drive beam 130 is supported by the movable frame 350, and the mirror section 110 can rotate around the first axis. In the optical deflector in this embodiment, the drive beam 130 serves as the main-scanning drive beam.

Moreover, on both sides of the movable frame 350, movable frame support parts 360 with a meandering structure are provided. The movable frame support part 360 has a plurality of beam parts 361 whose longitudinal direction is the X-axis direction, beam part connection parts 362 that connect adjacent beam parts 361, and piezoelectric members 363 provided on each beam part 361. One end of each movable frame support part 360 is connected to the movable frame 350, and the other end is connected to the fixed frame 370.

In the optical deflector of this embodiment, the entire movable frame 350 including the mirror section 110 can be rotated about the second axis by applying a voltage to the piezoelectric members 363 provided on each beam section 361.

In the above explanation, an example was described in which the optical deflector in the second embodiment is placed inside the movable frame 350, but it is also possible to place the optical deflector in the first or third embodiment inside the movable frame 350.

The optical deflectors according to the first to fourth embodiments described above can be used in optical scanning systems, image projection devices, optical writing devices, and object recognition devices.

[Optical scanning system]
First, an optical scanning system incorporating any one of the optical deflectors according to the first to fourth embodiments will be described in detail with reference to FIGS.

Figure 13 shows a schematic diagram of an example of an optical scanning system.

As shown in FIG. 13, the optical scanning system 10 is a system that deflects light irradiated from a light source device 12 by a reflecting surface 14 of an optical deflector 13 under the control of a driving device 11 to optically scan a scanned surface 15. The optical deflector 13 is any one of the optical deflectors according to the first to fourth embodiments.

The optical scanning system 10 includes a driving device 11, a light source device 12, and an optical deflector 13 having a reflecting surface 14. The optical scanning system 10 is a representative example of a deflection device according to the present invention.

The driving device 11 is, for example, an electronic circuit unit equipped with a CPU (Central Processing Unit) and an FPGA (Field-Programmable Gate Array). The optical deflector 13 is, for example, a MEMS (Micro Electromechanical Systems) device that has a reflective surface 14 and can move the reflective surface 14. The light source device 12 is, for example, a laser device that irradiates a laser. The scanned surface 15 is, for example, a screen.

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

The light source device 12 emits light based on the input drive signal. The optical deflector 13 moves the reflecting surface 14 in at least one axial direction or two axial directions based on the input drive signal.

As a result, the driving device 11, for example, by controlling based on image information, which is an example of optical scanning information, moves the reflecting surface 14 of the optical deflector 13 back and forth in two axial directions within a predetermined range, deflecting the irradiation light from the light source device 12 that is incident on the reflecting surface 14 to perform optical scanning. As a result, the driving device 11 can project any image onto the scanned surface 15.

Details about the control by the drive unit 11 will be described later.

Next, referring to FIG. 14, we will explain the hardware configuration of an example of the optical scanning system 10.

Figure 14 is a hardware configuration diagram of an example of an optical scanning system 10.

As shown in FIG. 14, the optical scanning system 10 includes a driving device 11, a light source device 12, and an optical deflector 13, all of which are electrically connected to each other.

[Drive unit]
The driving device 11 includes a CPU 20 , a RAM (Random Access Memory) 21 , a ROM (Read Only Memory) 22 , an FPGA 23 , an external I/F 24 , a light source device driver 25 , and an optical deflector driver 26 .

The CPU 20 is a calculation device that reads programs and data from storage devices such as the ROM 22 onto the RAM 21 and executes processing to realize the overall control and functions of the drive device 11. The RAM 21 is a volatile storage device that temporarily stores programs and data.

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

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

The external I/F 24 is, for example, an interface with an external device or a network. Examples of external devices include higher-level devices such as a PC (Personal Computer), and storage devices such as a USB memory, an SD card, a CD, a DVD, a HDD, or an SD. Examples of networks include an automobile's CAN (Controller Area Network), a LAN (Local Area Network), or the Internet. The external I/F 24 may have any configuration that enables connection or communication with an external device, and an external I/F 24 may be provided for each external device.

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

The optical deflector driver 26 is an electrical circuit that outputs a drive signal, such as a drive voltage, to the optical deflector 13 according to the input control signal.

In the drive device 11, the CPU 20 acquires optical scanning information from an external device or a network via the external I/F 24. The drive device 11 may be configured to store the optical scanning information in the ROM 22 or FPGA 23 within the drive device 11 as long as the CPU 20 can acquire the optical scanning information. The drive device 11 may also be configured to store the optical scanning information in a new internal storage device such as an SSD.

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

The drive device 11 can realize the functional configuration described below using instructions from the CPU 20 and the hardware configuration shown in FIG. 14.

[Functional configuration of the drive device]
Next, a functional configuration of the driving device 11 of the optical scanning system 10 will be described with reference to Fig. 15. Fig. 15 is a functional block diagram of an example of the driving device of the optical scanning system.

As shown in FIG. 15, the drive device 11 has the functions of a control unit 30 and a drive signal output unit 31.

The control unit 30 is realized by, for example, a CPU 20 and an FPGA 23, and acquires optical scanning information from an external device, converts the optical scanning information into a control signal, and outputs it to the drive signal output unit 31. For example, the control unit 30 is a control means, and acquires image data from an external device, etc. as optical scanning information, generates a control signal from the image data by performing a predetermined process, and outputs it to the drive signal output unit 31.

The drive signal output unit 31 is an application means, and is realized by the light source device driver 25 and the optical deflector driver 26, etc., and outputs a drive signal to the light source device 12 or the optical deflector 13 based on the input control signal. The drive signal output unit 31 (application means) may be provided, for example, for each target to which the drive signal is output.

The drive signal is a signal for controlling the drive of the light source device 12 or the optical deflector 13. For example, in the light source device 12, the drive signal is a drive voltage that controls the timing and intensity of the light source irradiation. Also, for example, in the optical deflector 13, the drive signal is a drive voltage that controls the timing and range of movement of the reflective surface 14 of the optical deflector 13. The drive device may obtain the light source irradiation timing and light receiving timing from an external device such as the light source device 12 or a light receiving device, and synchronize these with the drive of the optical deflector 13.

[Optical scanning process]
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. 16. Fig. 16 is a flowchart of an example of a process related to the optical scanning system.

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

In step S12, the control unit 30 generates a control signal from the acquired optical scanning information and outputs the control signal to the drive signal output unit 31.

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

In step S14, the light source device 12 emits light based on the input drive signal. The optical deflector 13 moves the reflecting surface 14 based on the input drive signal. By driving the light source device 12 and the optical deflector 13, the light incident on the reflecting surface 14 is deflected in an arbitrary direction and optically scanned.

In the optical scanning system 10, one driving device 11 controls the light source device 12 and the optical deflector 13, but a driving device that controls the light source device 12 and a driving device that controls the optical deflector 13 may be provided separately.

In addition, in the optical scanning system 10, one driving device 11 is provided with the functions of the control unit 30 and the driving signal output unit 31. However, these functions may exist separately, for example, a driving signal output device having a driving signal output unit 31 may be provided separately from the driving device 11 having the control unit 30. Note that, in the optical scanning system 10, an optical deflector 13 having a reflective surface 14 and the driving device 11 may form an optical deflection system that performs optical deflection.

By using the optical deflectors according to the first to fourth embodiments in an optical scanning system, optical scanning with a wide angle of view and high resolution of the movable part becomes possible.

[Image Projection Device]
Next, an image projection device to which the optical deflector 13 is applied will be described in detail with reference to FIGS.

Figure 17 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, Figure 18 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. 17, the head-up display device 500 is installed, for example, near the windshield (windshield 401, etc.) of the automobile 400. Projection light L emitted from the head-up display device 500 is reflected by the windshield 401 and directed toward the observer (driver 402), who is the user.

This allows the driver 402 to view the image 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, and the user may view a virtual image by projected light reflected by the combiner.

As shown in FIG. 18, in the head-up display device 500, laser light is emitted from red, green, and blue laser light sources 501R, 501G, and 501B. The emitted laser light is incident on an incident optical system including collimator lenses 502, 503, and 504 provided for each laser light source, two dichroic mirrors 505 and 506, and a light amount adjustment unit 507. The laser light that passes through the incident optical system is deflected by an optical deflector 13 having a reflecting surface 14.

The deflected laser light then passes through a projection optical system that includes 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 collimating lenses 502, 503, and 504, and the dichroic mirrors 505 and 506 are unitized in an optical housing as the light source unit 530.

The head-up display device 500 projects an intermediate image displayed on an intermediate screen 510 onto the windshield 401 of the automobile 400, allowing the driver 402 to view the intermediate image as a virtual image.

The laser light of each color emitted from the laser light sources 501R, 501G, and 501B is converted into approximately parallel light by the collimating lenses 502, 503, and 504, respectively, and is combined by two dichroic mirrors 505 and 506. The combined laser light has its light amount adjusted by the light amount adjustment unit 507, and is then two-dimensionally scanned by the optical deflector 13 having a reflecting surface 14. The projection light L two-dimensionally scanned by the optical deflector 13 is reflected by the free-form surface mirror 509, where distortion is corrected, and then focused on the intermediate screen 510 to display an intermediate image. The intermediate screen 510 is, for example, a microlens array in which microlenses are arranged two-dimensionally, and the projection light L incident on the intermediate screen 510 is magnified in units of microlenses.

The optical deflector 13 moves the reflecting surface 14 back and forth in two axial directions, two-dimensionally scanning the projection light L incident on the reflecting surface 14. The drive control of the reflecting surface 14 by the optical deflector 13 is performed in synchronization with the light emission timing of the laser light sources 501R, 501G, and 501B.

The above describes the head-up display device 500 as an example of an image projection device, but the image projection device may be a device other than a head-up display device as long as it projects an image by performing optical scanning using an optical deflector 13 having a reflective surface 14.

The image projection device can be similarly applied to, for example, a projector that is placed on a desk or the like and projects an image onto a display screen. The image projection device can also be similarly applied to a head-mounted display device that is mounted on a mounting member that is worn on the observer's head or the like and projects an image onto a reflective/transmissive screen that the mounting member has, or projects an image using the observer's eyeball as a screen.

The image projection device may be mounted not only on vehicles or mounting members, but also on moving bodies such as aircraft, ships, and mobile robots, or on non-moving bodies such as work robots that operate drive targets such as manipulators without moving from their locations.

By using the optical deflectors according to the first to fourth embodiments in an image projection device, it becomes possible to project images with a wide angle of view and high resolution from the movable part.

[Optical writing device]
Next, an optical writing device to which the optical deflector 13 is applied will be described in detail with reference to FIGS.

Figure 19 shows an example of an image forming device incorporating an optical writing device 600. Also, Figure 20 is a schematic diagram of an example of an optical writing device.

As shown in FIG. 19, the optical writing device 600 is used as a component of an image forming device such as a laser printer 650 having a printer function using laser light. In the image forming device, the optical writing device 600 optically writes on the photosensitive drum, which is the scanned surface 15, by optically scanning the photosensitive drum with one or more laser beams.

As shown in FIG. 20, in an optical writing device 600, laser light from a light source device 12 such as a laser element passes through an imaging optical system 601 such as a collimator lens, and is then deflected in one or two axial directions by an optical deflector 13 having a reflecting surface 14.

The laser light deflected by the optical deflector 13 then passes through the scanning optical system 602, which includes a first lens 602a, a second lens 602b, and a reflecting mirror section 602c, and is irradiated onto the surface to be scanned 15 (e.g., a photosensitive drum or photosensitive paper) to perform optical writing. The scanning optical system 602 forms a spot-shaped light beam on the surface to be scanned 15.

In addition, the light source device 12 and the optical deflector 13 having the reflective surface 14 are driven based on the control of the driving device 11.

In this way, the optical writing device 600 can be used as a component of an image forming device that has a laser light printer function.

The optical writing device 600 can also perform optical scanning in two directions, not just one, by changing the scanning optical system. The optical writing device 600 can be used, for example, as a component of an image forming device such as a laser label device that deflects laser light onto thermal media to perform optical scanning in two directions and prints by heating the thermal media.

The optical deflector 13 having a reflecting surface 14 used in the optical writing device described above consumes less power to operate than a rotating polygon mirror using a polygon mirror or the like, and is therefore advantageous in reducing the power consumption of the optical writing device.

In addition, the wind noise generated by the optical deflector 13 during vibration is smaller than that of the rotating polygon mirror, which is advantageous in improving the quietness of the optical writing device. The optical writing device requires an overwhelmingly smaller installation space than the rotating polygon mirror, and the optical deflector 13 generates only a small amount of heat, making it easy to miniaturize the device, which is advantageous in miniaturizing the image forming device.

By using the optical deflectors according to the first to fourth embodiments in an optical writing device, optical writing with a wide angle of view and high resolution of the movable part becomes possible.

[Object Recognition Device]
Next, an object recognition device to which the optical deflector 13 is applied will be described in detail with reference to FIGS.

Figure 21 is a schematic diagram of an automobile equipped with a laser radar device, which is an example of an object recognition device. Also, Figure 22 is a schematic diagram of an example of a laser radar device.

An object recognition device is a device that recognizes objects in a target direction, such as a laser radar device.

As shown in FIG. 21, the laser radar device 700 is mounted on, for example, an automobile 701, and recognizes an object 702 by optically scanning the target direction and receiving reflected light from the object 702 present in the target direction.

As shown in FIG. 22, the laser light emitted from the light source device 12 passes through an incident optical system including a collimator lens 703, which is an optical system that converts divergent light into approximately parallel light, and a plane mirror 704, and is scanned in one or two axial directions by an optical deflector 13 having a reflecting surface 14.

The laser light scanned in two axial directions is then irradiated onto the object 702 in front of the device via a projection lens 705, which is a projection optical system. The light source device 12 and the optical deflector 13 are controlled by a driving device 11. The light reflected by the object 702 is optically detected by a photodetector 709.

That is, the light reflected by the object 702 passes through the light receiving optical system, such as the condenser lens 706, and is received by the image sensor 707, which outputs a detection signal to the 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.

The distance measurement circuit 710 recognizes the presence or absence of the object 702 based on the time difference between when the light source device 12 emits the laser light and when the photodetector 709 receives the laser light, or the phase difference between each pixel of the image sensor 707 that receives the light. The distance measurement circuit 710 further calculates distance information to the object 702.

The optical deflector 13 with the reflecting surface 14 is less prone to breakage than a polygon mirror and is small, making it possible to provide a small, highly durable radar device.

Such a laser radar device can be mounted on a moving body such as a vehicle, an aircraft, a ship, or a mobile robot, or on a non-moving body such as a work robot that operates a drive target such as a manipulator without moving from the spot. The laser radar device can optically scan a predetermined range to recognize the presence or absence of an obstacle and the distance to the obstacle.
In the above, the laser radar device 700 has been described as an example of an object recognition device, but the object recognition device is not limited to a laser radar device. The object recognition device may be a device other than a laser radar device as long as it performs optical scanning by controlling an optical deflector 13 having a reflecting surface 14 with a driving device 11 and recognizes an object 702 by receiving reflected light with a photodetector.

The object recognition device can be similarly applied to biometric authentication, for example, where object information such as shape is calculated from distance information obtained by optically scanning a hand or face, and the target object is recognized by referring to the record. The object recognition device can also be similarly applied to security sensors that recognize intruding objects by optically scanning a target range, and to components of three-dimensional scanners that calculate and recognize object information such as shape from distance information obtained by optical scanning, and output it as three-dimensional data.

By using the optical deflectors according to the first to fourth embodiments in an object recognition device, it becomes possible to recognize objects with a wide angle of view and high resolution of the movable part.

[Packaging]
Next, packaging of the optical deflector 13 will be described with reference to FIG.

Figure 23 is a schematic diagram of an example of a packaged optical deflector.

As shown in FIG. 23, the optical deflector 13 is attached to a mounting member 802 that is placed on the bottom surface of a concave packaging member 801. The packaging member 801 is provided with a transparent member 803 that covers the area in which the optical deflector 13 is placed. The optical deflector 13 is packaged by being sealed with the packaging member 801 and the transparent member 803.

In addition, an inert gas such as nitrogen is sealed inside the package. This prevents the optical deflector 13 from deteriorating due to oxidation, and improves its durability against environmental changes such as temperature.

Although the above describes examples of embodiments of the present invention, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims.

10 Optical scanning system 11 Driving device 12, 12b Light source device 13 Optical deflector 14 Reflecting surface 15 Scanned surface 25 Light source device driver 26 Optical deflector driver 30 Control unit 31 Drive signal output unit 50 Laser headlamp 51 Mirror 52 Transparent plate 110 Mirror portion 120 Torsion bar 120a One end 120b The other end 130 Drive beam 131 Beam portion 132 Piezoelectric material 140 Connection portion 141 Connection portion rib 142 Fixed end side fillet 143 Convex portion 144 Free end side fillet 150 Fixed frame 350 Movable frame 360 Movable frame support portion 361 Beam portion 362 Beam portion connection portion 363 Piezoelectric member 370 Fixed frame 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 Laser radar device (an example of an object recognition device)
702 Object 801 Package member 802 Mounting member 803 Transparent member

JP 2019-144416 A

Claims (15)

A mirror portion that reflects light;
a pair of support parts each having one end connected to the mirror part and supporting the mirror part;
a pair of drive beams connected to the other end of each of the supports and configured to deform the supports to rotate the mirror unit about a first axis;
a connection portion that connects the support portion and the actuation beam;
having
The connection portion is provided with a rib having a longitudinal direction intersecting with a longitudinal direction of the pair of support portions,
An optical deflector characterized in that, when a plane parallel to the reflective surface of the mirror section when the pair of drive beams are not driven is bisected by a straight line parallel to the longitudinal direction of the pair of support sections, the pair of drive beams are positioned on either of the bisected planes. The optical deflector according to claim 1, characterized in that the rib is provided in a direction perpendicular to the first axis. The optical deflector according to claim 1 or 2, characterized in that the rib is provided on the side of the connection portion opposite to the side connected to the mirror portion. A frame portion supporting the actuation beam is provided.
4. The optical deflector according to claim 1, wherein a member consisting of said drive beam, said connection portion, said support portion and said mirror portion is cantilevered by said frame portion. the connection portion is connected to the actuation beam in a first region on a side of the actuation beam relative to the first axis,
a second region of the connection portion opposite to the first region has a protrusion that protrudes from a portion where the drive beam and the frame portion are connected to each other,
5. The optical deflector according to claim 4, wherein a first fillet portion having a fillet shape is provided on the support portion side of the protrusion. The optical deflector according to claim 5, characterized in that a second fillet portion having a fillet shape is provided on the support portion side of the first region of the connection portion. The optical deflector according to claim 6, characterized in that the rib is provided so as to straddle a virtual line along the first axis direction from the end point of the second fillet portion closest to the actuation beam. a second fillet portion having a fillet shape is provided on the support portion side of the first region of the connection portion,
6. The optical deflector according to claim 5, wherein a curvature of the fillet shape of the first fillet portion is different from a curvature of the fillet shape of the second fillet portion. The optical deflector according to any one of claims 5 to 8, characterized in that the fillet shape of the first fillet portion is an elliptical arc. The optical deflector according to any one of claims 5 to 9, characterized in that the fillet shape of the first fillet portion is an arc and is formed within a range of 90 degrees or less with respect to the center of the arc. The frame portion is a movable frame,
a pair of movable frame support parts each having one end connected to the movable frame and supporting the movable frame rotatably about a second axis perpendicular to the first axis;
a fixed frame to which the other end of the movable frame support portion is connected; and
11. The optical deflector according to claim 4, further comprising: An optical deflector according to any one of claims 1 to 10;
A light source;
A deflection device comprising: An object recognition device comprising an optical deflector according to any one of claims 1 to 10. An image projection device comprising an optical deflector according to any one of claims 1 to 10. A moving body having at least one of the object recognition device according to claim 13 and the image projection device according to claim 14.

Images