JP7501281B2 - Optical deflector, deflection device, distance measuring device, image projection device, and moving body - Google Patents

Description

The present invention relates to an optical deflector, a deflection device, a distance measuring 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, which are manufactured by microfabricating silicon and glass.

A known MEMS device is a two-dimensional optical deflector in which a mirror section with a reflective surface, a torsion bar, and a beam section (elastic beam) are integrally formed on a wafer, and the mirror section is driven (rotated) by a piezoelectric actuator constructed by layering a thin film of piezoelectric material on the beam section.

In the two-dimensional optical deflector described above, a configuration has been disclosed in which the support layer of the mirror section is formed with a thickness different from that of the support layer of the piezoelectric beam section. (For example, Patent Document 1)

However, in conventional two-dimensional optical deflectors, one or two pairs of first piezoelectric actuators are arranged opposite each other across a torsion bar, and the first AC voltage applied to the piezoelectric actuator on one side of the torsion bar and the second AC voltage applied to the piezoelectric actuator on the other side of the torsion bar are 180 degrees out of phase with each other. This causes the vibration of the first piezoelectric actuator (main scanning) that is 180 degrees out of phase to propagate to the movable frame connected to the first piezoelectric actuator and the second piezoelectric actuator (sub-scanning), which can cause unintended rotation (vibration) around the rotation axis (first axis) in the movable frame. When an image is formed using such an optical deflector, it is not possible to form a high-quality image.

The present invention has been made in consideration of the above points, and aims to provide an optical deflector that can produce high-quality images when forming an image using the optical deflector.

An optical deflector according to one aspect of the disclosed technology includes a mirror section that reflects light, a pair of support sections each connected at one end to the mirror section and supporting the mirror section, a pair of first actuator sections each connected to the other end of each of the support sections and configured to deform the support section to rotate the mirror section around a first axis, a movable frame that supports the first actuator section, and a second actuator section connected to the movable frame on the opposite side of the first axis to the first actuator section, wherein the second actuator section is not connected to the support section, and when the mirror section is in a rotatable state, the first actuator section and the second actuator section are capable of bending and deforming in the same direction.

The disclosed technology makes it possible to form an image with high image quality when using an optical deflector.

FIG. 2 is a structural diagram showing an example of an optical deflector having a cantilever structure. FIG. 2 is a structural diagram showing an example of an optical deflector having a double-supported structure. FIG. 1 is a structural diagram of an optical deflector according to a first embodiment; FIG. 2 is a structural diagram of the optical deflector according to the first embodiment; FIG. 3 is a structural diagram of the optical deflector according to the first embodiment; FIG. 1 is an explanatory diagram (1) of an optical deflector according to a first embodiment. FIG. 2 is an explanatory diagram (2) of the optical deflector according to the first embodiment. 5 is an explanatory diagram of a driving waveform of the optical deflector in the first embodiment. FIG. 11 is a structural diagram of an optical deflector according to a second 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. FIG. 1 is a schematic diagram of an example of an automobile equipped with a lidar device. FIG. 1 is a schematic diagram of an example of a lidar device. FIG. 2 is a schematic diagram illustrating 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
First, an optical deflector in which two or four piezoelectric actuators for deflecting light in the main scanning direction are all connected to a mirror portion will be described.

Figure 1 shows a cantilevered optical deflector in which two piezoelectric actuator sections 903a, 903b for deflecting light in the main scanning direction are all connected to a mirror section 101.

The mirror section 101 has a reflecting surface 14 that reflects light. The torsion bars 902a and 902b connect the mirror section 101 to the piezoelectric actuator sections 903a and 903b, and support the mirror section 101 in a state in which it can rotate around a first axis. The movable frame 104 supports the piezoelectric actuator sections 903a and 903b on the inside of the movable frame 104.

A pair of piezoelectric actuator units 905a, 905b are provided on the outside of the movable frame 104 to support the movable frame 104 in a rotatable state around the second axis. The piezoelectric actuator units 905a, 905b are provided between the movable frame 104 and the fixed frame 106, and the fixed frame 106 supports the piezoelectric actuator units 905a, 905b.

The piezoelectric actuator units 903a and 903b are formed with a lower electrode, a piezoelectric unit, and an upper electrode, which are not shown, in that order. The piezoelectric actuator units 903a and 903b are supported by the movable frame 104 and connected to the torsion bars 902a and 902b, and are deformed when a drive voltage is applied via the upper and lower electrodes. The deformation of the piezoelectric unit causes the piezoelectric actuator units 903a and 903b to bend and deform, and the torsion bars 902a and 902b to twist.

Figure 2 also shows a double-supported optical deflector in which all four piezoelectric actuators 913a, 913b, 913c, and 913d for deflecting light in the main scanning direction are connected to the mirror section 101.

The torsion bars 902a and 902b connect the mirror section 101 to the piezoelectric actuator sections 913a, 913b, 913c, and 913d, and support the mirror section 101 in a state in which it can rotate around the first axis. The movable frame 104 supports the piezoelectric actuator sections 913a, 913b, 913c, and 913d on the inside of the movable frame 104.

In addition, a lower electrode, a piezoelectric portion, and an upper electrode (not shown) are formed in this order on the piezoelectric actuator portions 913a, 913b, 913c, and 913d. The piezoelectric actuator portions 913a, 913b, 913c, and 913d, which are supported by the movable frame 104 and to which the torsion bars 902a and 902b are connected, deform when a drive voltage is applied via the upper and lower electrodes. Due to the deformation of the piezoelectric portion, the piezoelectric actuator portions 913a, 913b, 913c, and 913d bend and deform, and the torsion bars 902a and 902b twist.

In the optical deflector shown in FIG. 1 or FIG. 2, vibrations caused by the piezoelectric actuator on the main scanning side are transmitted to the movable frame connected to the piezoelectric actuator on the main scanning side and to the piezoelectric actuator on the sub-scanning side, and in some cases, unintended extra rotation (vibration) occurs in the movable frame around the rotation axis (first axis). In this way, when unintended extra vibrations are applied to the optical deflector, it becomes difficult to accurately perform the desired optical deflection. For example, when an image is formed using this optical deflector, dark lines or the like may appear in the formed image, resulting in a decrease in image quality. For this reason, there is a demand for an optical deflector that can form high-quality images.

The optical deflector in the first embodiment will be described. The optical deflector in this embodiment is a two-dimensional optical deflector that uses a piezoelectric actuator, as shown in FIG. 3.

The optical deflector in this embodiment has a mirror section 101, a pair of torsion bars 102a, 102b, a pair of first piezoelectric actuator sections 103a, 103b, second piezoelectric actuator sections 103c, 103d, a movable frame 104, third piezoelectric actuator sections 105a, 105b, and a fixed frame 106. Note that in this application, the torsion bars may be referred to as a support section.

The mirror section 101 has a reflecting surface 14 that reflects light. The torsion bars 102a and 102b connect the mirror section 101 to the first piezoelectric actuator sections 103a and 103b, and support the mirror section 101 in a state in which it can rotate around a first axis. Specifically, the torsion bars 102a and 102b have one end connected to the mirror section 101 and the other end connected to the first piezoelectric actuator sections 103a and 103b.

The movable frame 104 supports the first piezoelectric actuator parts 103a and 103b and the second piezoelectric actuator parts 103c and 103d on the inside of the movable frame 104. Specifically, the first piezoelectric actuator parts 103a and 103b are supported on the -X side of the inside of the movable frame 104, and the second piezoelectric actuator parts 103c and 103d are supported on the +X side. The first piezoelectric actuator parts 103a and 103b and the second piezoelectric actuator parts 103c and 103d are provided at positions facing each other with respect to the first axis, and more preferably at positions approximately symmetrical with respect to the first axis. The second piezoelectric actuator parts 103c and 103d are not connected to the torsion bars 102a and 102b.

A pair of third piezoelectric actuators 105a and 105b are provided on the outside of the movable frame 104 to support the movable frame 104 in a rotatable state around the second axis. The third piezoelectric actuators 105a and 105b are provided between the movable frame 104 and the fixed frame 106, and the fixed frame 106 supports the third piezoelectric actuators 105a and 105b. The first axis and the second axis are perpendicular to each other. The third piezoelectric actuators 105a and 105b are provided with a plurality of beams extending in the Y direction, and adjacent beams are connected by a connection portion. The beams provided on the third piezoelectric actuators 105a and 105b are each provided with a piezoelectric drive portion, and the piezoelectric drive portions in the piezoelectric drive portion group A and the piezoelectric drive portions in the piezoelectric drive portion group B are provided alternately. Each piezoelectric drive portion is provided with a lower electrode, a piezoelectric portion, and an upper electrode (not shown) in that order.

The first piezoelectric actuator units 103a and 103b are formed with a lower electrode, a piezoelectric unit, and an upper electrode, which are not shown, in that order. The first piezoelectric actuator units 103a and 103b are supported by a movable frame 104 and connected to the other ends of the torsion bars 102a and 102b, and are deformed when a drive voltage is applied via the upper and lower electrodes. The deformation of the piezoelectric unit causes the first piezoelectric actuator units 103a and 103b to bend and deform, and the torsion bars 102a and 102b to twist.

The twisting of the torsion bars 102a and 102b becomes a rotational force, and the mirror section 101 rotates back and forth around the first axis. The waveform of the drive voltage applied to the first piezoelectric actuator sections 103a and 103b is a sine wave or the like, and the mirror section 101 resonates and rotates back and forth with the period of the sine wave drive voltage waveform.

The second piezoelectric actuator units 103c and 103d are deformed when a drive voltage is applied through the upper and lower electrodes. The second piezoelectric actuator units 103c and 103d are bent and deformed due to the deformation of the piezoelectric units, but because they are not connected to the torsion bars 102a and 102b, no rotational torque is generated to rotate the mirror unit 101.

Therefore, the first piezoelectric actuator units 103a, 103b and the second piezoelectric actuator units 103c, 103d supported by the movable frame 104 are bent and deformed when a drive voltage is applied. As a result, vibrations are also transmitted to the movable frame 104 and the second piezoelectric actuator units 103c, 103d.

In this embodiment, the waveforms of the AC voltage applied to the first piezoelectric actuator units 103a and 103b and the AC voltage applied to the second piezoelectric actuator units 103c and 103d are set to be approximately in phase, preferably in phase. This reduces unnecessary movement of the movable frame 104 rotating around the first axis due to vibrations propagated from the first piezoelectric actuator units 103a and 103b and the second piezoelectric actuator units 103c and 103d. In addition, by reducing unnecessary movement of the movable frame 104, the driving force of the first piezoelectric actuator units 103a and 103b is efficiently transmitted to the mirror unit 101, thereby improving the driving sensitivity of the mirror unit 101.

In other words, if the mirror rotation natural frequency of the vibration system formed by the mirror section 101, the torsion bars 102a, 102b, and the first piezoelectric actuator sections 103a, 103b is f1, then the beam bending natural frequency f2 of the vibration system formed by the second piezoelectric actuator sections 103c, 103d is adjusted relative to the mirror rotation natural frequency f1, so that the mirror rotation natural frequency f1 and the beam bending natural frequency f2 are made equal and driven in phase. This makes it possible to efficiently reduce unnecessary motion propagated from the first piezoelectric actuator sections 103a, 103b to the movable frame 104.

For example, as shown in FIG. 3, the width and length of the second piezoelectric actuator units 103c and 103d are made wider and longer than the first piezoelectric actuator units 103a and 103b. This increases the moment of inertia of the second piezoelectric actuator units 103c and 103d, and allows the beam bending natural frequency f2 to be adjusted relative to the mirror rotation natural frequency f1 of the vibration system including the first piezoelectric actuator units 103a and 103b. Note that the first piezoelectric actuator units 103a and 103b and the second piezoelectric actuator units 103c and 103d are preferably piezoelectric elements having substantially the same characteristics. By using piezoelectric elements having substantially the same characteristics, a high-quality image can be formed.

Also, as shown in Figures 4A and 4B, the width of the end portions 103e and 103f of the second piezoelectric actuator portions 103c and 103d opposite to the side connected to the movable frame 104 may be adjusted by making them wider than the other portions. This makes it possible to increase the moment of inertia of the second piezoelectric actuator portions 103c and 103d. In this way, the beam bending natural frequency f2 can be adjusted relative to the mirror rotation natural frequency f1 of the vibration system including the first piezoelectric actuator portions 103a and 103b.

In this case, it is preferable that the shape of the side closest to the mirror section 101 at the ends 103e and 103f of the second piezoelectric actuator sections 103c and 103d is a shape that follows at least a part of the outer periphery of the mirror section 101. For example, as shown in FIG. 4B, it is preferable that the sides S1 and S2 facing the mirror section 101 at the ends 103e and 103f are shaped to follow the shape of the outer periphery of the mirror section 101 closest to the sides S1 and S2. This makes it possible to prevent contact with the mirror section 101 while obtaining a large moment of inertia, thereby forming a high-quality image. Note that FIG. 4B illustrates a case in which the outer periphery of the mirror section 101 is a circle, but the same applies to a case in which the outer periphery of the mirror section 101 is a shape other than a circle.

Next, the driving of the optical deflector in this embodiment will be described with reference to Figures 5 and 6. Figures 5 and 6 are cross-sectional views taken along dashed line 3A-3B in Figure 3. Figure 5 shows the state in which the second piezoelectric actuator units 103c and 103d are not driven, and Figure 6 shows the state in which the second piezoelectric actuator units 103c and 103d are driven.

Figure 5 shows the case where the first piezoelectric actuator units 103a and 103b are driven without driving the second piezoelectric actuator units 103c and 103d. In this case, forces act in opposite directions on the side of the movable frame 104 connected to the first piezoelectric actuator units 103a and 103b and the opposing side of the movable frame 104 across the rotation axis (first axis). That is, as shown by the dashed arrow, when an upward force acts on the side of the movable frame 104 connected to the first piezoelectric actuator units 103a and 103b, a downward force acts on the opposing side of the movable frame 104 across the rotation axis (first axis).

As a result, a moment of inertia occurs and the movable frame 104 rotates around the rotation axis (first axis) of the mirror section 101. In this case, however, in addition to the original rotation of the mirror section 101, an extra rotation occurs in the movable frame 104. This makes it easier for misalignment to occur in the image drawn by the optical deflector.

In this embodiment, as shown in Fig. 6, the AC voltage applied to the first piezoelectric actuator units 103a and 103b and the AC voltage applied to the second piezoelectric actuator units 103c and 103d are applied in the same phase. In this case, as shown in Fig. 6, a force acts in the same direction on the side of the movable frame 104 connected to the first piezoelectric actuator units 103a and 103b and on the opposing side of the movable frame 104 across the rotation axis (first axis). That is, as shown by the dashed arrow, when a downward force acts on the side of the movable frame 104 connected to the first piezoelectric actuator units 103a and 103b, a downward force also acts on the opposing side of the movable frame 104 across the rotation axis (first axis). This reduces unnecessary movement of the movable frame 104 rotating about the first axis due to vibrations propagated from the first piezoelectric actuator units 103a, 103b and the second piezoelectric actuator units 103c, 103d.

That is, the beam bending natural frequency f2 of the vibration system composed of the second piezoelectric actuator units 103c and 103d is adjusted relative to the mirror rotation natural frequency f1 of the vibration system including the first piezoelectric actuator units 103a and 103b. This makes the mirror rotation natural frequency f1 and the beam bending natural frequency f2 equal and drives them in phase. This makes it possible to more efficiently reduce unnecessary motion propagated from the first piezoelectric actuator units 103a and 103b to the movable frame 104.

At this time, the first piezoelectric actuator units 103a, 103b and the second piezoelectric actuator units 103c, 103d are driven in the same phase, eliminating the need to add a special drive circuit to adjust the phase. This makes it possible to suppress deterioration in image quality due to the addition of a special drive circuit, and to form high-quality images. In addition, since there is no need to add a special circuit, the device can be made smaller and driven more simply.

Figure 7 shows the drive waveforms applied to the first piezoelectric actuator units 103a and 103b and the second piezoelectric actuator units 103c and 103d of the optical deflector in this embodiment. When it is difficult to adjust the natural frequencies f1 and f2, adjusting the drive voltages of the second piezoelectric actuator units 103c and 103d makes it possible to more efficiently reduce the excess motion propagating from the first piezoelectric actuator units 103a and 103b to the movable frame 104, thereby forming a high-quality image.

Specifically, when the natural frequency f1 and the natural frequency f2 are significantly different, the drive voltage of the second piezoelectric actuator units 103c and 103d is adjusted relative to the first piezoelectric actuator units 103a and 103b. This makes it possible to make the force generated on the side of the movable frame 104 to which the first piezoelectric actuator units 103a and 103b are connected the same as the force generated on the side to which the second piezoelectric actuator units 103c and 103d are connected. As a result, unnecessary rotational movement of the movable frame 104 can be reduced. The voltage relationship may be reversed as long as the force generated on the movable frame 104 is the same.

The inventors of the present invention have confirmed through finite element simulation that it is possible to reduce excess rotation in the movable frame 104 to less than half by adjusting the shape (width, length) and drive voltage of the second piezoelectric actuator parts 103c and 103d.

Second Embodiment
Next, a description will be given of an optical deflector in a second embodiment. The optical deflector in this embodiment is a two-dimensional optical deflector using a piezoelectric actuator, as shown in FIG.

The optical deflector in this embodiment has a mirror section 101, a pair of torsion bars 102a, 102b, a pair of first piezoelectric actuator sections 203a, 203b, a pair of fourth piezoelectric actuator sections 203c, 203d, a fifth piezoelectric actuator section 203e, a second piezoelectric actuator section 203f, a movable frame 104, a third piezoelectric actuator section 105a, 105b, and a fixed frame 106.

The mirror section 101 has a reflecting surface 14 that reflects light. One end of the torsion bar 102a is connected to the mirror section 101, and the other end is connected to the first piezoelectric actuator section 203a and the fourth piezoelectric actuator section 203c. One end of the torsion bar 102b is connected to the mirror section 101, and the other end is connected to the first piezoelectric actuator section 203b and the fourth piezoelectric actuator section 203d. The mirror section 101 is supported by the pair of torsion bars 102a and 102b in a state in which it can rotate around the first axis.

The movable frame 104 supports the first piezoelectric actuator units 203a and 203b and the fourth piezoelectric actuator units 203c and 203d on the inside of the movable frame 104. Specifically, the first piezoelectric actuator units 203a and 203b are supported on the -X side of the inside of the movable frame 104, and the fourth piezoelectric actuator units 203c and 203d are supported on the +X side.

Furthermore, the fifth piezoelectric actuator part 203e is supported on the inner -X side of the movable frame 104, and the second piezoelectric actuator part 203f is supported on the inner +X side of the movable frame 104. The fifth piezoelectric actuator part 203e and the second piezoelectric actuator part 203f are not connected to the torsion bars 102a and 102b.

A pair of third piezoelectric actuator units 105a, 105b are provided on the outside of the movable frame 104, which support the movable frame 104 in a state in which the movable frame 104 can rotate around the second axis. The third piezoelectric actuator units 105a, 105b are provided between the movable frame 104 and the fixed frame 106, and the fixed frame 106 supports the third piezoelectric actuator units 105a, 105b.

The first piezoelectric actuator units 203a, 203b and the fourth piezoelectric actuator units 203c, 203d, which are supported by the movable frame 104 and to which the other ends of the torsion bars 102a, 102b are connected, deform when a drive voltage is applied through the upper electrode and the lower electrode. Due to the deformation of the piezoelectric units, the first piezoelectric actuator units 203a, 203b and the fourth piezoelectric actuator units 203c, 203d bend and deform, and the torsion bars 102a, 102b twist.

The twisting of the torsion bars 102a and 102b becomes a rotational force, and the mirror section 101 rotates back and forth around the first axis. The waveform of the drive voltage applied to the first piezoelectric actuator sections 203a and 203b and the fourth piezoelectric actuator sections 203c and 203d is a sine wave or the like. The drive waveform applied to the first piezoelectric actuator sections 203a and 203b and the drive waveform applied to the fourth piezoelectric actuator sections 203c and 203d are 180 degrees out of phase with each other, and the mirror section 101 resonates and rotates back and forth with the period of the sine wave drive voltage waveform.

The fifth piezoelectric actuator unit 203e and the second piezoelectric actuator unit 203f supported by the movable frame 104 are deformed when a drive voltage is applied through the upper electrode and the lower electrode. The fifth piezoelectric actuator unit 203e and the second piezoelectric actuator unit 203f are bent and deformed by the deformation of the piezoelectric unit, but since they are not connected to the torsion bars 102a and 102b, no rotational torque is generated to rotate the mirror unit 101.

The first piezoelectric actuator units 203a and 203b, the fourth piezoelectric actuator units 203c and 203d, the fifth piezoelectric actuator unit 203e, and the second piezoelectric actuator unit 203f supported by the movable frame 104 undergo bending deformation when a drive voltage is applied. This bending deformation also propagates vibrations to the movable frame 104 and the third piezoelectric actuator units 105a and 105b.

In this embodiment, the waveforms of the AC voltages applied to the first piezoelectric actuator units 203a and 203b and the second piezoelectric actuator unit 203f are in phase with each other. In addition, the waveforms of the AC voltages applied to the fourth piezoelectric actuator units 203c and 203d and the fifth piezoelectric actuator unit 203e are in phase with each other. This makes it possible to reduce unnecessary movement of the movable frame 104 rotating about the first axis due to vibrations propagated from the first piezoelectric actuator units 203a and 203b and the fourth piezoelectric actuator units 203c and 203d.

The optical deflector according to the present embodiment described above can be used in optical scanning systems, image projection devices, optical writing devices, and distance measuring devices.

[Optical scanning system]
First, an optical scanning system to which a driving device according to an embodiment of the present invention is applied will be described in detail with reference to FIGS.

Figure 9 shows a schematic diagram of an example of an optical scanning system.

As shown in FIG. 9, 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 surface 15 to be scanned.

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, for example, by controlling the driving device 11 based on image information, which is an example of optical scanning information, the reflecting surface 14 of the optical deflector 13 can be moved back and forth in two axial directions within a predetermined range, and the irradiation light from the light source device 12 that is incident on the reflecting surface 14 can be deflected and optically scanned, thereby projecting any image onto the scanned surface 15.

Details of the optical deflector and the control by the drive device of this embodiment will be described later.

Next, referring to FIG. 10, the hardware configuration of an example of the optical scanning system 10 will be described.

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

As shown in FIG. 10, 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]
Of these, the driving device 11 includes a CPU 20, a RAM (Random Access Memory), a ROM (Read Only Memory), an FPGA 23, an external I/F 24, a light source device driver 25, and an optical deflector driver .

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 USB memory, SD cards, CDs, DVDs, HDDs, and SSDs. Examples of networks include an automobile's CAN (Controller Area Network) or LAN (Local Area Network), the Internet, etc. 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. Note that any configuration is acceptable as long as the CPU 20 is capable of acquiring optical scanning information, and the optical scanning information may be stored in the ROM 22 or FPGA 23 in the drive device 11, or a new storage device such as an SSD may be provided in the drive device 11, and the optical scanning information may be stored in that storage device.

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 and writing locations. 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 according to this embodiment can realize the functional configuration described below by using instructions from the CPU 20 and the hardware configuration shown in FIG. 10.

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

As shown in FIG. 11, 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, the CPU 20, FPGA 23, etc., 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 constitutes a control means, 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 constitutes an application means, and is realized by the light source device driver 25, 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, it is a drive voltage that controls the timing and intensity of the light source irradiation. Also, for example, in the optical deflector 13, it 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 reception 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. 12. Fig. 12 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 is deflected in an arbitrary direction and optical scanning is performed.

In the optical scanning system 10, one driving device 11 has the device and function to control the light source device 12 and the optical deflector 13, but the driving device for the light source device and the driving device for the optical deflector 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 of the light source device 12 and the optical deflector 13 and the function of the driving signal output unit 31, but these functions may exist separately, for example, a configuration may be adopted in which a driving signal output device having a driving signal output unit 31 is 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 deflector according to this embodiment in an optical scanning system, optical scanning with high image quality becomes possible.

[Image Projection Device]
Next, an image projection device to which the driving device of this embodiment is applied will be described in detail with reference to FIG. 13 and FIG.

Figure 13 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 14 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. 13, 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. 14, 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 passes through an incident optical system consisting of collimating lenses 502, 503, and 504 provided for each laser light source, two dichroic mirrors 505 and 506, and a light amount adjustment unit 507, and is then deflected by an optical deflector 13 having a reflecting surface 14.

The deflected laser light then passes through a projection optical system consisting 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 collimating lenses 502, 503, and 504, and the dichroic mirrors 505 and 506 are unitized by 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 collimating lenses 502, 503, and 504, respectively, and then combined by two dichroic mirrors 505 and 506. The combined laser light has its light amount adjusted by a light amount adjustment unit 507, and is then two-dimensionally scanned by an optical deflector 13 having a reflecting surface 14. The projection light L two-dimensionally scanned by the optical deflector 13 is reflected by a free-form mirror 509, where distortion is corrected, and then focused on an intermediate screen 510 to display an intermediate image. The intermediate screen 510 is composed of a microlens array in which microlenses are arranged two-dimensionally, and the projection light L entering 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 this 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 any device that projects an image by performing optical scanning using an optical deflector 13 having a reflective surface 14.

For example, it can be similarly applied to a projector that is placed on a desk or the like and projects an image onto a display screen, or a head-mounted display device that is mounted on a mounting member that is attached to 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 onto the observer's eyeball as a screen.

The image projection device may be mounted not only on a vehicle or a mounting member, but also on a moving body such as 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 its location.

By using the optical deflector according to this embodiment in an image projection device, it becomes possible to project images with high image quality.

[Optical writing device]
Next, an optical writing device to which the driving device 11 of this embodiment is applied will be described in detail with reference to FIG. 15 and FIG.

Figure 15 shows an example of an image forming device incorporating an optical writing device 600. Figure 16 is a schematic diagram of an example of an optical writing device.

As shown in FIG. 15, 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. 16, 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 axes by an optical deflector 13 having a reflecting surface 14.

The laser light deflected by the optical deflector 13 then passes through a scanning optical system 602 consisting of a first lens 602a, a second lens 602b, and a reflecting mirror section 602c, and is irradiated onto a 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 printer function using laser light.

In addition, by changing the scanning optical system to enable optical scanning not only in one axis direction but also in two axes directions, it can be used as a component of an image forming device such as a laser label device that deflects a laser beam onto thermal media, optically scans the media, and prints by heating it.

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 deflector according to this embodiment in an optical writing device, optical writing with high image quality becomes possible.

[Distance measuring device]
Next, a distance measuring device to which the driving device of the present embodiment is applied will be described in detail with reference to FIG. 17 and FIG.

Figure 17 is a schematic diagram of an automobile equipped with a LiDAR (Laser Imaging Detection and Ranging) device, which is an example of a distance measuring device. Also, Figure 18 is a schematic diagram of an example of a LiDAR 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. 17, the lidar 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. The lidar device 700 may be mounted on a lighting unit that mounts the headlights of the automobile for the purpose of collecting information on the traveling direction, or a total of four or more lidar devices may be provided on each of the front, rear, left and right of the vehicle. Note that the object on which the lidar device 700 is mounted is not limited to an automobile, and may be a measurement vehicle for the purpose of collecting information on road information and features, or a moving body such as a general vehicle for the purpose of moving passengers, transporting passengers, or transporting.

As shown in FIG. 18, the laser light emitted from the light source device 12 passes through an input optical system consisting of 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 light then passes through a projection lens 705, which is a projection optical system, and is irradiated onto an object 702 in front of the device. 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 reflected light passes through the collecting lens 706, which is a light receiving optical system, 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 laser light is received by the photodetector 709, or the phase difference between each pixel of the image sensor 707 that receives the light, and further calculates the 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 lidar device can be attached to, for example, a vehicle, an aircraft, a ship, a robot, etc., and can optically scan a predetermined range to recognize the presence or absence of an obstacle and the distance to the obstacle. In the above distance measurement device, the lidar device 700 has been described as an example, but the distance measurement device may be any device that performs optical scanning by controlling the optical deflector 13 having a reflective surface 14 with the driving device 11, and recognizes the target object 702 by receiving the reflected light with a photodetector, and is not limited to the above-mentioned embodiment.

For example, it can be used in biometric authentication, 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 referencing the record; security sensors recognize intruders by optically scanning a target range; and components of 3D scanners that calculate and recognize object information such as shape from distance information obtained by optical scanning, and output it as 3D data.

By using the optical deflector according to this embodiment in a distance measuring device, it becomes possible to recognize objects with high accuracy and calculate distance information to the object with high accuracy.

[Packaging]
Next, with reference to FIG. 19, packaging of the optical deflector controlled by the driving device of this embodiment will be described.

Figure 19 is a schematic diagram of an example of a packaged optical deflector.

As shown in FIG. 19, the optical deflector 13 is attached to a mounting member 802 that is placed inside a packaging member 801, and a portion of the packaging member is covered with a transparent member 803, and the optical deflector 13 is packaged by being sealed.

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 60 Head mounted display 60a Front 60b Temple 61 Light guide plate 62 Half mirror 63 Wearer 101 Mirror unit 102a, 102b Torsion bar 103a, 103b First piezoelectric actuator unit 103c, 103d Second piezoelectric actuator unit 104 Movable frame 105a, 105b Third piezoelectric actuator unit 400 Automobile (one 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 a distance measuring device)
701 Automobile 702 Object 801 Package member 802 Mounting member 803 Transparent member

Japanese Patent No. 5506976

Claims (14)

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 first actuator units 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 movable frame supporting the first actuator unit;
a second actuator unit connected to the movable frame on the opposite side of the first axis from the first actuator unit;
having
the second actuator portion is not connected to the support portion;
13. An optical deflector, comprising: a first actuator section and a second actuator section each capable of bending and deforming in the same direction when the mirror section is in a rotatable state. 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 first actuator units 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 movable frame supporting the first actuator unit;
a second actuator unit connected to the movable frame on the opposite side of the first axis from the first actuator unit;
having
2. An optical deflector according to claim 1, wherein the second actuator portion is not connected to the support portion. 3. The optical deflector according to claim 1 , wherein, in a state in which the mirror section is rotatable, the first actuator section and the second actuator section are bent and deformed in the same phase. a third actuator unit having one end connected to the movable frame and supporting the movable frame;
a fixed frame connected to the other end of the third actuator portion;
4. The optical deflector according to claim 1, wherein the third actuator portion supports the movable frame so as to be rotatable about a second axis perpendicular to the first axis. 5. The optical deflector according to claim 1, wherein the second actuator section is provided at a position symmetrical to the first actuator section with respect to the first axis. 6. The optical deflector according to claim 5 , wherein the first actuator element and the second actuator element have different shapes. 7. The optical deflector according to claim 6 , wherein a shape of the side of the second actuator element closest to the mirror element follows at least a part of an outer periphery of the mirror element. a pair of fourth actuator units, one end of which is connected to the movable frame, the fourth actuator units being provided at positions symmetrical to the first actuator units with respect to the first axis;
a fifth actuator unit connected to the movable frame on the opposite side of the first axis from the fourth actuator unit; and
having
the other end of the fourth actuator portion is connected to the support portion,
5. The optical deflector according to claim 1, wherein the fifth actuator portion is not connected to the support portion. a pair of fourth actuator units, one end of which is connected to the movable frame, the fourth actuator units being provided at positions symmetrical to the first actuator units with respect to the first axis;
a fifth actuator unit connected to the movable frame on the opposite side of the first axis from the fourth actuator unit; and
having
the other end of the fourth actuator portion is connected to the support portion,
the fifth actuator portion is not connected to the support portion,
4. The optical deflector according to claim 3 , wherein the fourth actuator unit and the fifth actuator unit are bent and deformed in a phase that is 180 degrees different from that of the first actuator unit and the second actuator unit. a third actuator unit having one end connected to the movable frame and supporting the movable frame;
a fixed frame connected to the other end of the third actuator portion;
10. The optical deflector according to claim 9, wherein the third actuator section supports the movable frame so as to be rotatable about a second axis perpendicular to the first axis. An optical deflector according to any one of claims 1 to 10 ;
A light source;
A deflection device comprising: A distance measuring device comprising the optical deflector according to any one of claims 1 to 10 . An image projection device comprising the optical deflector according to claim 1 . A moving object comprising at least one of the distance measuring device according to claim 12 and the image projection device according to claim 13 .

Images