Driving device, projection device, head-mounted display, head-up display, laser headlamp, object recognition device, mobile device, driving method and program

Abstract

The drive unit is precisely controlled using a drive signal that includes multiple frequency components. [Solution] A drive device according to one aspect of the present disclosure comprises a movable part, a drive unit for driving the movable part, a drive control unit for controlling the drive unit with a drive signal containing a plurality of frequency components, and a detection unit for detecting the displacement of the movable part, wherein the drive control unit corrects the frequency components included in the drive signal based on the combined frequency component of the plurality of frequency components decomposed from the detection signal by the detection unit.

Description

[Technical Field]

[0001] This disclosure relates to a drive device, a projection device, a head-mounted display, a head-up display, a laser headlamp, an object recognition device, a mobile device, a drive method, and a program. [Background technology]

[0002] For example, Patent Document 1 discloses an optical scanning device in which the first drive signal and the second drive signal are periodic voltage signals whose amplitude and phase change over time, respectively, and the mirror unit is made to perform a spiral rotation operation that includes a period in which the oscillation amplitude around the first axis and the oscillation amplitude around the second axis change linearly. [Overview of the project] [Problems that the invention aims to solve]

[0003] However, in the technology described in Patent Document 1, the control accuracy of the drive unit may be reduced when the drive signal contains multiple frequency components.

[0004] This disclosure aims to precisely control a drive unit using a drive signal that includes multiple frequency components. [Means for solving the problem]

[0005] A drive device according to one aspect of the present disclosure comprises a movable part, a drive unit for driving the movable part, a drive control unit for controlling the drive unit with a drive signal containing a plurality of frequency components, and a detection unit for detecting the displacement of the movable part, wherein the drive control unit corrects the frequency components included in the drive signal based on the combined frequency component of the plurality of frequency components decomposed from the detection signal by the detection unit. [Effects of the Invention]

[0006] According to this disclosure, the drive unit can be precisely controlled using a drive signal that includes multiple frequency components. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic top view showing a first example of the overall configuration of the drive device according to the first embodiment. [Figure 2] This is a schematic cross-sectional view along the second axis in Figure 1. [Figure 3] This is a schematic cross-sectional view along line III-III in Figure 1. [Figure 4] This is a schematic top view showing a second example of the overall configuration of the drive device according to the first embodiment. [Figure 5] This is a block diagram illustrating the hardware configuration of the drive control unit included in the drive device according to the first embodiment. [Figure 6] This is a block diagram illustrating the functional configuration of the drive control unit included in the drive device according to the first embodiment. [Figure 7] This figure shows an example of a drive signal for spiral scanning. [Figure 8] This figure shows an example of a drive signal with a fundamental cycle applied to the first piezoelectric drive unit. [Figure 9] This figure shows an example of the ratio of the amplitude increase period to the amplitude decrease period and the ratio of the cavity diameter to the overall field of view. [Figure 10] This figure shows an example of the trajectory of reflected light from the reflector when a drive signal for spiral scanning is input. [Figure 11] This figure illustrates a first example of a method for correcting a drive signal using a drive device according to the first embodiment. [Figure 12] This figure illustrates a second example of a method for correcting a drive signal using a drive device according to the first embodiment. [Figure 13] This figure illustrates a third example of a method for correcting the drive signal using a drive device according to the first embodiment. [Figure 14] This is a flowchart showing the correction process of the drive signal by the drive control unit of the drive device according to the first embodiment. [Figure 15A] This figure shows an example of a drive signal that has not been corrected by the drive device according to the first embodiment. [Figure 15B]This is a diagram illustrating an example of displacement of a movable portion driven by the drive signal shown in FIG. 15A. [Figure 15C] This is a diagram illustrating an example of a drive signal corrected by the drive device according to the first embodiment. [Figure 15D] This is a diagram illustrating an example of displacement of a movable portion driven by the drive signal shown in FIG. 15C. [Figure 16] This is a schematic diagram illustrating an example of an optical scanning system including the drive device according to the first embodiment. [Figure 17] This is a flowchart illustrating an example of a processing procedure executed in the optical scanning system including the drive device according to the first embodiment. [Figure 18] This is a schematic diagram illustrating an example of an automobile equipped with a head-up display device according to the second embodiment. [Figure 19] This is a schematic diagram illustrating an example of the head-up display device according to the second embodiment. [Figure 20] This is a perspective view illustrating an example of an image forming apparatus equipped with an optical writing device according to the third embodiment. [Figure 21] This is a schematic diagram illustrating an example of the optical writing device according to the third embodiment. [Figure 22] This is a schematic diagram illustrating a first example of an automobile equipped with a laser radar device according to the fourth embodiment. [Figure 23] This is a schematic diagram illustrating a second example of an automobile equipped with a laser radar device according to the fourth embodiment. [Figure 24] This is a schematic cross-sectional view illustrating an example of the laser radar device according to the fourth embodiment. [Figure 25] This is a schematic diagram illustrating an example of a laser headlamp according to the fifth embodiment. [Figure 26] This is a perspective view illustrating an example of a head-mounted display according to the sixth embodiment. [Figure 27] This is a schematic cross-sectional view partially illustrating the head-mounted display according to the sixth embodiment. [Figure 28] This is a schematic configuration diagram illustrating an example of a pupil or cornea position detection device including a drive device according to the seventh embodiment. [Figure 29] This is a schematic diagram showing an example of a pupil or corneal position detection device equipped with a drive device according to the seventh embodiment. [Modes for carrying out the invention]

[0008] The embodiments for carrying out the invention will be described below with reference to the drawings. In each drawing, the same reference numerals are used for identical components, and redundant explanations may be omitted.

[0009] In the following description of the embodiments, rotation, oscillation, and movement are considered synonymous. Also, in some figures, parallel diagonal lines are drawn on parts that are not cross-sections. In some cases, end view diagrams showing only the cut surface are used as cross-sectional views. In this specification, the positional relationship expressed as "above" includes cases where the parts are in contact with each other, and cases where the parts are not in contact but are located above each other. The positional relationship expressed as "below" includes cases where the parts are in contact with each other, and cases where the parts are not in contact but are located below each other. Furthermore, "to position" is not limited to cases where the parts are in direct contact, but also includes cases where the parts are positioned indirectly, for example, via other members.

[0010] In drawings, the XYZ Cartesian coordinate system may be used to represent direction. The X, Y, and Z axes are orthogonal to each other. In the X direction along the X axis, the direction in which the arrow is pointing is denoted as the +X side, and the opposite direction is denoted as the -X side. In the Y direction along the Y axis, the direction in which the arrow is pointing is denoted as the +Y side, and the opposite direction is denoted as the -Y side. In the Z direction along the Z axis, the direction in which the arrow is pointing is denoted as the +Z side, and the opposite direction is denoted as the -Z side. In this specification, for example, the +Z side corresponds to "up" and the -Z side corresponds to "down". Viewing an object from the +Z side is called a "top view". Unless otherwise specified, the Z direction corresponds to the thickness direction. However, these directions do not limit the orientation of the drive device according to the embodiments of this disclosure, and the orientation of the drive device according to the embodiments of this disclosure is arbitrary.

[0011] [First Embodiment] <Overall configuration of the drive device according to the first embodiment> (First example of a drive device according to the first embodiment) A first example of a drive device according to the first embodiment of the present disclosure will be described with reference to Figures 1 to 3. Figure 1 is a schematic top view showing a first example of the overall configuration of a drive device 13 according to the first embodiment of the present disclosure. Figure 2 is a schematic cross-sectional view along the second axis of Figure 1. Figure 3 is a schematic cross-sectional view along line III-III of Figure 1.

[0012] As shown in Figures 1 to 3, the drive device 13 comprises a movable part 101, drive units 110a and 110b that drive the movable part 101, and a drive control unit 11 that controls the drive units 110a and 110b with a drive signal containing multiple frequency components. The drive device 13 also comprises detection units 160a and 160b that detect the displacement of the movable part 101. The drive device 13 is a device that controls the drive units 110a and 110b by the drive control unit 11, and can swing the movable part 101 around the first axis as the center of rotation. Note that the notation "drive units 110a and 110b" is synonymous with "drive unit 110a and drive unit 110b," and the repeated notation of "drive unit" has been replaced with a comma to shorten the explanation. The same applies to the notation "detection units 160a and 160b." Hereafter, for the same purpose, repeated notations of component names may be replaced with a comma.

[0013] In typical drive systems, when the drive signal contains multiple frequency components, the control accuracy of the drive unit may be reduced due to the influence of the combined frequency generated by nonlinear effects.

[0014] In the embodiments of this disclosure, the drive control unit 11 corrects the frequency components included in the drive signal based on the combined frequency component of multiple frequency components decomposed from the detection signals by the detection units 160a and 160b. As a result, the drive device 13 can correct the influence of the combined frequency generated by nonlinear effects, even when the drive signal contains multiple frequency components. As a result, the drive device 13 can accurately control the drive units 110a and 110b using a drive signal containing multiple frequency components. The method for correcting the frequency components included in the drive signal by the drive device according to the first embodiment of this disclosure will be described in detail separately with reference to Figures 11 to 15.

[0015] In the example shown in Figure 1, the drive device 13 further comprises, in a top view, a first support frame 120 surrounding the movable part 101 and the drive units 110a and 110b, and first support frame drive units 130a and 130b that drive the first support frame 120. Furthermore, in a top view, the drive device 13 further comprises a second support frame 140 surrounding the first support frame 120 and the first support frame drive units 130a and 130b, and electrode connection units 150 that are electrically connected to the drive units 110a and 110b, the first support frame drive units 130a and 130b, and the drive control unit 11. The drive control unit 11 further controls the first support frame drive units 130a and 130b, allowing the movable part 101 to swing around the second axis as the center of rotation.

[0016] The drive unit 13 can be formed by etching a single SOI (Silicon On Insulator) substrate. The reflective portion 14, the first piezoelectric drive portions 112a, 112b, the second piezoelectric drive portions 131a, 131b, 131c, 131d, 131e, 131f, and the electrode connection portion 150, which will be described later, are formed on the SOI substrate. These may be formed after the molding of the SOI substrate or during the molding of the SOI substrate.

[0017] In the examples shown in Figures 2 and 3, the SOI substrate on which the drive unit 13 is formed includes a silicon support layer 161 made of single-crystal silicon (Si). The SOI substrate also includes a silicon oxide layer 162 formed on the +Z side of the silicon support layer 161, and a silicon active layer 163 made of single-crystal silicon formed on the silicon oxide layer 162. The silicon oxide layer 162 can also be referred to as a BOX (Buried Oxide) layer.

[0018] A component composed solely of the silicon active layer 163 functions as an elastic part. The SOI substrate does not necessarily have to be planar and may have curvature or other properties. The component used to form the drive device 13 is not limited to an SOI substrate and may be a partially elastic substrate that can be integrally formed by etching or the like.

[0019] (Movable part 101) In the example shown in Figure 1, the movable part 101 includes a reflective part 14 that reflects light. In a top view, the movable part 101 further includes a movable part base 102 having a circular outer shape, and a movable thickened part 103 for reinforcing the mirror part, formed on the -Z side surface of the movable part base 102.

[0020] The reflective portion 14 is formed on the +Z side surface of the movable portion base 102. The movable portion base 102 includes a silicon active layer 163. The reflective portion 14 includes a metal film containing aluminum, gold, silver, etc. The movable thickened portion 103 includes a silicon support layer 161 and a silicon oxide layer 162. The movable thickened portion 103 can suppress distortion of the reflective portion 14 caused by movement.

[0021] (Drive unit 110a, 110b) In the example shown in Figure 1, the drive unit 110a comprises a torsion bar 111a, a first piezoelectric drive unit 112a, and a drive beam 113a. The drive unit 110b comprises a torsion bar 111b, a first piezoelectric drive unit 112b, and a drive beam 113b.

[0022] Torsion bars 111a and 111b are support parts that extend in the Y direction and elastically support the movable part 101. One end of torsion bars 111a and 111b is connected to the movable part 101. The other end of torsion bar 111a is connected to one end of drive beam 113a. The other end of torsion bar 111b is connected to one end of drive beam 113b. The other ends of drive beams 113a and 113b are connected to the first support frame 120. One end of the first piezoelectric drive unit 112a is connected to torsion bar 111a and the other end is connected to the first support frame 120. One end of the first piezoelectric drive unit 112b is connected to torsion bar 111b and the other end is connected to the first support frame 120.

[0023] From another perspective, the first piezoelectric drive units 112a and 112b are positioned apart in the Y direction and extend in the X direction. The first piezoelectric drive unit 112a connects the torsion bar 111a to the inner circumference of the first support frame 120. The first piezoelectric drive unit 112b connects the torsion bar 111b to the inner circumference of the first support frame 120.

[0024] The drive unit 110a has a cantilevered structure in which the drive beam 113a and the first piezoelectric drive unit 112a extend from the torsion bar 111a toward the +X side. The drive unit 110b has a cantilevered structure in which the first piezoelectric drive unit 112b extends from the torsion bar 111b toward the +X side. The drive unit 110a causes the torsion bar 111a to twist and deform by the first piezoelectric drive unit 112a, and the drive unit 110b causes the torsion bar 111b to twist and deform. Due to this torsional deformation, the drive units 110a and 110b can swing the movable part 101 around the first axis as the center of rotation. The first axis is a predetermined swing axis.

[0025] The drive units 110a and 110b are not limited to a single-end support structure, and may have a double-end support (double-support) structure as long as the movable part 101 can swing due to the piezoelectric part 202 to which a drive voltage is applied. The torsion bars 111a and 111b and the first piezoelectric drive units 112a and 112b may each have curvature. The drive method of the drive units 110a and 110b is not limited to a piezoelectric method, but may be an electrostatic method, an electromagnetic method, a thermoelectric method, or the like.

[0026] In the example shown in Figure 3, the torsion bars 111a and 111b include a silicon active layer 163. The first piezoelectric drive units 112a and 112b each comprise a lower electrode 301, a piezoelectric unit 302, and an upper electrode 303. The lower electrode 301, the piezoelectric unit 302, and the upper electrode 303 are laminated in this order on the +Z side surface of the silicon active layer 163, which is the elastic part. The upper electrode 303 and the lower electrode 301 contain gold (Au) or platinum (Pt), etc. The piezoelectric unit 302 contains a piezoelectric material such as PZT (lead zirconate titanate).

[0027] (First support slot: 120) The first support frame 120 supports the movable part 101 and the drive parts 110a and 110b. In the examples shown in Figures 1 and 3, the first support frame 120 has a rectangular annular shape when viewed from above. The movable part 101 and the drive parts 110a and 110b are located inside the first support frame 120 when viewed from above. The first support frame 120 includes a silicon support layer 161, a silicon oxide layer 162, and a silicon active layer 163.

[0028] (First support frame drive unit 130a, 130b) The first support frame drive unit 130a includes second piezoelectric drive units 131a, 131b, 131c, 131d, 131e, and 131f. The first support frame drive unit 130b includes second piezoelectric drive units 132a, 132b, 132c, 132d, 132e, and 132f. The first support frame drive units 130a and 130b are connected to the first support frame 120. The first support frame drive units 130a and 130b cause the movable part 101 and the first support frame 120 to swing around a second axis parallel to the X axis as the center of rotation. The second support frame 140 supports the first support frame drive units 130a and 130b.

[0029] The second piezoelectric drive units 131a, 131b, 131c, 131d, 131e, and 131f included in the first support frame drive unit 130a are constructed by connecting multiple beam sections in a folded manner. The second piezoelectric drive units 132a, 132b, 132c, 132d, 132e, and 132f included in the first support frame drive unit 130b are constructed by connecting multiple beam sections in a folded manner. One end of the first support frame drive units 130a and 130b is connected to the outer circumference of the first support frame 120, and the other end is connected to the inner circumference of the second support frame 140.

[0030] The connection points between the first support frame drive unit 130a and the first support frame 120, and between the first support frame drive unit 130b and the first support frame 120, are point-symmetric with respect to the center of the reflective section 14. The connection points between the first support frame drive unit 130a and the second support frame 140, and between the first support frame drive unit 130b and the second support frame 140, are point-symmetric with respect to the center of the reflective section 14.

[0031] In the example shown in Figure 2, the second piezoelectric drive units 131a, 131b, 131c, 131d, 131e, 131f and the second piezoelectric drive units 132a, 132b, 132c, 132d, 132e, 132f each comprise a lower electrode 201, a piezoelectric unit 202, and an upper electrode 203. The lower electrode 201, the piezoelectric unit 202, and the upper electrode 203 are laminated in this order on the +Z side surface of the silicon active layer 163, which is an elastic part. The upper electrode 203 and the lower electrode 201 contain gold (Au) or platinum (Pt), etc. The piezoelectric unit 202 contains a piezoelectric material such as PZT (lead zirconate titanate).

[0032] (Second support slot: 140) In the examples shown in Figures 1 and 2, the second support frame 140 has a rectangular annular shape when viewed from above. The movable part 101, the drive parts 110a and 110b, the first support frame 120, and the first support frame drive parts 130a and 130b are arranged inside the second support frame 140 when viewed from above. The second support frame 140 includes a silicon support layer 161, a silicon oxide layer 162, and a silicon active layer 163.

[0033] (Electrode connection part 150) In the example shown in Figure 1, the multiple electrode connection portions 150 are formed on the +Z side of the portion of the second support frame 140 that includes the -Y side, when viewed from above. The upper electrode 303 and lower electrode 301 of the first piezoelectric drive units 112a and 112b are electrically connected to the multiple electrode connection portions 150. The upper electrode 203 and lower electrode 201 of the second piezoelectric drive units 131a, 131b, 131c, 131d, 131e, 131f and 132a, 132b, 132c, 132d, 132e, 132f are also connected to the multiple electrode connection portions 150. Furthermore, the drive control unit 11 is connected to the multiple electrode connection portions 150.

[0034] (Upper electrodes 203, 303, piezoelectric parts 202, 302, lower electrodes 201, 301) The upper electrode 303, lower electrode 301, upper electrode 203, lower electrode 201, and drive control unit 11 are electrically connected to a plurality of electrode connection parts 150 via electrode wiring. The electrode wiring is made of aluminum (Al) or the like. A signal voltage is applied to the lower electrode 201, and the upper electrode 203 is grounded (GND). A signal voltage is applied to the lower electrode 301, and the upper electrode 303 is grounded (GND).

[0035] Each of the upper electrode 203 and lower electrode 201 is directly connected to the electrode connection part 150. Each of the upper electrode 303 and lower electrode 301 is directly connected to the electrode connection part 150. The piezoelectric part 202 is provided on the other side of the elastic part (for example, the -Z side). However, each of the upper electrode 203 and lower electrode 201 may be indirectly connected by connecting the electrodes together, etc. Each of the upper electrode 303 and lower electrode 301 may be indirectly connected by connecting the electrodes together, etc. The piezoelectric part 202 may be provided on both sides of one and the other side of the elastic part.

[0036] In the drive unit 13, an insulating layer made of a silicon oxide film may be formed on at least one of the following surfaces: the +Z side surface of the upper electrode 303 of each of the drive unit 110a and drive unit 110b, the +Z side surface of the first support frame 120, the +Z side surface of the upper electrode 203 of each of the first support frame drive units 130a and 130b, and the +Z side surface of the second support frame 140. When an insulating layer is formed, electrode wiring is provided on the insulating layer, and the insulating layer may be partially removed as an opening or not formed at connection spots where the upper electrode 203, upper electrode 303, lower electrode 201 or lower electrode 301 are connected to the electrode wiring. This configuration increases the design flexibility of the drive units 110a and 110b, the first support frame drive units 130a and 130b, and the electrode wiring, and reduces short circuits due to contact between electrodes. The silicon oxide film can also function as an anti-reflective material.

[0037] (Detection units 160a, 160b) In the example shown in Figure 1, the detection unit 160a is provided on the +Z side of the drive beam 113a. The detection unit 160b is provided on the +Z side of the drive beam 113b. The detection units 160a and 160b are each composed of a piezoelectric material such as PZT (lead zirconate titanate).

[0038] The detection unit 160a generates a detection signal by piezoelectric effect in response to the deformation of the drive beam 113a and outputs the detection signal to the drive control unit 11 via the electrode connection unit 150. The detection unit 160b generates a detection signal by piezoelectric effect in response to the deformation of the drive beam 113b and outputs the detection signal to the drive control unit 11 via the electrode connection unit 150. The drive control unit 110a and 110b can be controlled based on the output signals of the respective detection units 160a and 160b.

[0039] Detection units such as detection units 160a and 160b can also detect the displacement of the movable part 101 by detecting the position of the light reflected by the reflecting part 14 of the movable part 101, and output a detection signal to the drive control unit 11. In this case, the detection unit is not necessarily formed on the drive beam, but is positioned in a location where it can receive the light reflected by the reflecting part 14.

[0040] (Second example of drive unit 13) Next, a second example of the drive unit 13 will be described. Note that names and reference numerals identical to those used in the previously described embodiments indicate the same or identical components or configurations, and detailed explanations will be omitted as appropriate. This also applies to the embodiments described later.

[0041] Figure 4 is a schematic top view showing the overall configuration of the second example of the drive unit 13. The drive unit 13 has a rectangular external shape when viewed from above. The drive unit 13 according to the second example differs from the drive unit 13 according to the first example in that, when viewed from above, it has four drive units, 110a, 110b, 110c, and 110d, which are arranged diagonally around the movable part 101.

[0042] The drive device 13 in the second example drives the movable part 101 with drive units 110a, 110b, 110c, and 110d, thereby scanning the reflected light from the reflecting part 14 of the movable part 101 along a line X11 parallel to the X direction and a line Y11 parallel to the Y direction. The drive device 13 performs so-called vector scanning, Lissajous scanning, or spiral scanning, and can display an image using the scanned light, for example. The field of view center O14 corresponds to the field of view center when performing vector scanning, Lissajous scanning, or spiral scanning.

[0043] In the example shown in Figure 4, the second support frame 140 has a rectangular annular shape when viewed from above. The movable part 101 and the drive parts 110a, 110b, 110c, and 110d are located inside the second support frame 140 when viewed from above. The second support frame 140 supports the movable part 101 and the drive parts 110a, 110b, 110c, and 110d.

[0044] The drive unit 110a comprises a torsion bar 111a, a first piezoelectric drive unit 112a, and a drive beam 113a. The drive unit 110b comprises a torsion bar 111b, a first piezoelectric drive unit 112b, and a drive beam 113b. The drive unit 110c comprises a torsion bar 111c, a first piezoelectric drive unit 112c, and a drive beam 113c. The drive unit 110d comprises a torsion bar 111d, a first piezoelectric drive unit 112d, and a drive beam 113d. The drive beams 113a, 113b, 113c, and 113d are connected to four different corners inside the second support frame 140.

[0045] Torsion bar 111a has one end connected to the movable part 101 and the other end connected to the drive beam 113a. Torsion bar 111b has one end connected to the movable part 101 and the other end connected to the drive beam 113b. Torsion bar 111c has one end connected to the movable part 101 and the other end connected to the drive beam 113c. Torsion bar 111d has one end connected to the movable part 101 and the other end connected to the drive beam 113d.

[0046] The first piezoelectric drive unit 112a is formed on the +Z side surface of the drive beam 113a. The first piezoelectric drive unit 112b is formed on the +Z side surface of the drive beam 113b. The first piezoelectric drive unit 112c is formed on the +Z side surface of the drive beam 113c. The first piezoelectric drive unit 112d is formed on the +Z side surface of the drive beam 113d.

[0047] The multiple electrode connection portions 150 are formed on the +Z side of the portion of the second support frame 140 that includes the +X side, when viewed from above.

[0048] In the example shown in Figure 4, the movable part 101 and the drive parts 110, 110b, 110c, and 110d are formed from the same SOI substrate silicon active layer. The size or thickness of the movable part 101 and the drive parts 110a, 110b, 110c, and 110d in a top view can be changed as appropriate.

[0049] The detection unit 160a is formed on the +Z side surface of the drive beam 113a. The detection unit 160a extends in the longitudinal direction of the torsion bar 111a. The detection unit 160b is formed on the +Z side surface of the drive beam 113b. The detection unit 160b extends in the longitudinal direction of the torsion bar 111b. The detection unit 160c is formed on the +Z side surface of the drive beam 113c. The detection unit 160c extends in the longitudinal direction of the torsion bar 111c. The detection unit 160d is formed on the +Z side surface of the drive beam 113d. The detection unit 160d extends in the longitudinal direction of the torsion bar 111d.

[0050] The detection unit 160a generates a detection signal by piezoelectric effect in response to the deformation of the drive beam 113a and outputs it to the drive control unit 11 via the electrode connection unit 150. The detection unit 160b generates a detection signal by piezoelectric effect in response to the deformation of the drive unit 110b and outputs it to the drive control unit 11 via the electrode connection unit 150. The detection unit 160c generates a detection signal by piezoelectric effect in response to the deformation of the drive beam 113c and outputs it to the drive control unit 11 via the electrode connection unit 150. The detection unit 160d generates a detection signal by piezoelectric effect in response to the deformation of the drive beam 113d and outputs it to the drive control unit 11 via the electrode connection unit 150. The drive control unit 11 can control the drive units 110a and 110b based on the respective output signals from the detection units 160a and 160b.

[0051] <Configuration of the drive control unit 11> Next, the configuration of the drive control unit 11 will be described. The drive control unit 11 shown below is applicable to both the first and second example drive devices 13. For convenience, the following description will focus on the drive control unit 11 used in the second example drive device 13.

[0052] (Hardware configuration) Figure 5 is a block diagram showing an example of the hardware configuration of the drive control unit 11. In the example shown in Figure 5, the drive control unit 11 includes a CPU (Central Processing Unit) 20, RAM (Random Access Memory) 21, and ROM (Read Only Memory) 22. The drive control unit 11 also includes an FPGA (Field Programmable Gate Array) 23, an external I / F (Interface) 24, and a drive device driver 26. These are connected to each other so as to be able to communicate via the system bus B. The drive control unit 11 is electrically connected to the drive units 110a, 110b, 110c, 110d and the detection units 160a, 160b, 160c, 160d.

[0053] The CPU 20 is an arithmetic unit that controls the overall operation of the drive control unit 11 and realizes the functions of the drive control unit 11 described below by reading programs or data from a storage device such as ROM 22 into RAM 21 and executing the processing specified in the program. RAM 21 is a volatile storage device that temporarily holds programs or data. ROM 22 is a non-volatile storage device that can retain programs and data even when the power is turned off. ROM 22 stores processing programs or data that the CPU 20 executes to control each function of the drive control unit 11.

[0054] FPGA23 is an electronic circuit that outputs control signals suitable for the drive unit driver 26 according to the processing of the CPU 20. External I / F24 is an interface that controls communication between the drive control unit 11 and external devices or networks. Examples of external devices include information processing devices such as PCs (Personal Computers), or storage devices such as USB (Universal Serial Bus) memory, SD cards, CDs, DVDs, HDDs (Hard Disk Drives), and SSDs (Solid State Drives). Examples of networks include automotive CAN (Controller Area Network), LAN (Local Area Network), or the Internet. Note that the external I / F24 only needs to be configured to enable connection or communication between the drive control unit 11 and external devices, and an external I / F24 may be provided for each external device.

[0055] The drive unit driver 26 is an electrical circuit that supplies drive signals to the drive units 110a, 110b, 110c, and 110d according to the input control signal. The drive signal is a drive voltage. However, the drive signal may also be a drive current.

[0056] The CPU 20 receives and acquires optical scanning information from an external device or network via the external I / F 24. However, the CPU 20 is not limited to receiving optical scanning information via the external I / F 24; it may also acquire optical operation information by reading optical scanning information stored in the ROM 22 or HDD, etc., as long as it can acquire optical scanning information.

[0057] Optical scanning information includes information indicating how the light reflected by the reflective section 14 is scanned by the drive unit 13 on the surface to be scanned. When displaying an image on the surface to be scanned by scanning light, the image data that forms the basis of the displayed image can be used as optical scanning information. Furthermore, when optical writing is performed on a photosensitive drum or the like by scanning light, the writing data indicating the writing order and writing position can be used as optical scanning information. When object recognition is performed by scanning light, the optical scanning information can include irradiation data indicating the timing and range of irradiation for object recognition.

[0058] The drive control unit 11 can implement each of the functions of the drive control unit 11 described below, depending on the instructions of the CPU 20 and the hardware configuration.

[0059] (Functional Configuration) Figure 6 is a block diagram showing an example of the functional configuration of the drive control unit 11. In the example shown in Figure 6, the drive control unit 11 comprises a control unit 30, an input unit 31, and a drive signal output unit 32.

[0060] The functions of the control unit 30 are realized by the CPU 20 or FPGA 23, etc., executing processes defined by a program stored in ROM, etc. The functions of the input unit 31 are realized by the external I / F 24 or the CPU 20 or FPGA 23, etc., executing processes defined by a program stored in ROM, etc. The functions of the drive signal output unit 32 are realized by the drive device driver 26 or the external I / F 24, etc. However, some of the functions of the drive control unit 11 may be realized by equipment or devices other than the drive control unit 11, and may be realized by distributed processing between the drive control unit 11 and equipment or devices other than the drive control unit 11.

[0061] The control unit 30 acquires optical scanning information from an external device via the input unit 31, converts the optical scanning information into a control signal, and outputs it to the drive signal output unit 32. In the example shown in Figure 6, the control unit 30 acquires image data as optical scanning information from an external device, generates a control signal from the image data through predetermined processing, and outputs it to the drive signal output unit 32. The drive signal output unit 32 outputs drive signals to the drive units 110a, 110b, 110c, and 110d based on the input control signal.

[0062] The drive signal is a signal for controlling the drive units 110a, 110b, 110c, and 110d. For example, the drive signal is a drive voltage that controls the timing and range of motion for moving the reflector unit 14.

[0063] The first calculation unit 311 decomposes the detected output into frequency components. The "detected output" corresponds to the displacement of the movable part 101. The detection units 160a, 160b, 160c, and 160d detect the displacement of the movable part 101. The detection units 160a, 160b, 160c, and 160d output the detected displacement signal of the movable part 101 to the drive control unit 11.

[0064] The first arithmetic unit 311 decomposes the detected signal into frequency components and obtains amplitude and phase information for each frequency component. The first arithmetic unit 311 can perform FFT (Fast Fourier Transform) processing on the detected signal.

[0065] The second calculation unit 312 updates the drive signal based on the information from the first calculation unit 311. The information from the first calculation unit includes information regarding the amplitude and phase of each frequency component. The second calculation unit 312 can determine whether the amplitude and phase of each frequency component of the detected signal match a predetermined desired set. A "desired set" refers to a combination of amplitude and phase. The second calculation unit 312 can also modify the drive waveform based on the analysis results. In the second calculation unit 312, "drive waveform" refers to the drive waveform of the drive signal that formed the basis of the output of the movable part 101. "Analysis results" refers to the results of the frequency analysis.

[0066] The displacement of the movable part 101 is expressed by the following equation (1). In equation (1), A is a positive constant and represents the amplitude of the displacement of the movable part 101. π is the ratio of a circle's circumference to its diameter (pi). f1 and f2 are frequencies. A × sin(2π × f1) + A × sin(2π × f2) ... (1)

[0067] The second calculation unit 312 determines, based on the detection signal, whether the displacement of the movable part 101 follows a predetermined function. The function is, for example, the function of equation (1).

[0068] The displacement of the movable part 101 can also be expressed, for example, by the following equation (2). In equation (2), A1 and A2 are positive constants and represent the amplitude of the displacement of the movable part 101. Φ1 and Φ2 represent the phase of the displacement of the movable part 101. A1×sin(2π×f1+Φ1)+A2×sin(2π×f2+Φ2)...(2)

[0069] The second calculation unit 312 can also determine, based on the detection signal, whether the displacement of the movable part 101 conforms to equation (2) above. If the displacement of the movable part 101 conforms to equation (2) above, the second calculation unit 312 can update the input amplitude of the frequency components of f1, for example, so that the amplitude ratio of each frequency component becomes 1:1.

[0070] (Details of control by the drive control unit 11) The control by the drive control unit 11 will now be explained.

[0071] The drive control unit 11 applies a drive voltage to the drive units 110a, 110b, 110c, and 110d. The drive control unit 11 controls the drive voltage applied to the drive units 110a, 110b, 110c, and 110d. The drive control unit 11 can control the drive units 110a, 110b, 110c, and 110d based on the detection signals output by the detection units 160a, 160b, 160c, and 160d, respectively.

[0072] The drive voltage applied to the drive units 110a, 110b, 110c, and 110d is applied to the piezoelectric unit 302 via the upper electrode 303 and the lower electrode 301. As a result, the piezoelectric unit 302 of each of the drive units 110a, 110b, 110c, and 110d deforms (e.g., expands and contracts) in proportion to the potential of the applied drive voltage due to the so-called inverse piezoelectric effect. The deformation of the piezoelectric unit 302 causes the first piezoelectric drive units 112a, 112b, 112c, and 112d to bend. As a result, the twisting of the torsion bars 111a, 111b, 111c, and 111d generates a driving force that causes the movable unit 101 to rotate around the Z axis. The movable unit 101 rotates around the Z axis due to this driving force.

[0073] The angle formed between the XY plane and the reflecting part 14 of the movable part 101 when the reflecting part 14 is tilted in the +Z or -Z direction with respect to the XY plane is called the "angle of deflection". The +Z direction is called the positive angle of deflection, and the -Z direction is called the negative angle of deflection.

[0074] The drive control unit 11 applies a predetermined sinusoidal drive voltage to the drive units 110a, 110b, 110c, and 110d in parallel. As a result, the movable part 101 is driven to rotate around the Z-axis as the center of rotation at a period corresponding to the predetermined sinusoidal drive voltage.

[0075] The frequency of the drive voltage may be approximately the same as the resonant frequency of the torsion bars 111a, 111ab, 111c, and 111d. For example, if the resonant frequency of the torsion bars 111a, 111ab, 111c, and 111d is 20kHz, the drive control unit 11 applies a drive voltage with a frequency of 20kHz to the piezoelectric unit 302, thereby generating mechanical resonance due to twisting in the torsion bars 111a, 111ab, 111c, and 111d. As a result, the movable part 101 resonates and vibrates at approximately 20kHz.

[0076] For example, in a linear system such as the system equipped with the drive device 13 according to the second example, if the input signal is a single sine wave, the output will be a single sine wave of the same frequency. The single sine wave input signal is expressed by the following equation (3). The single sine wave output is expressed by the following equation (4). A 1_in ×cos(2π×f×t+Φ1)...(3) A 1_out ×cos(2π×f×t+Φ2)...(4)

[0077] In formula (3), A 1_in is a positive constant, which is the amplitude of the sine wave of the input signal. π is the circular constant. f is the frequency. Φ1 and Φ2 are the phases of the sine wave of the input signal. In formula (4), A 1_out is a positive constant, which is the amplitude of the sine wave of the output signal. in denotes the input, and out denotes the output.

[0078] The phase and amplitude of the output sine wave vary depending on the resonance frequency of the system, the Q value, and the frequency of the sine wave of the input signal. Further, in a linear system, when the input signal is a superposition of a plurality of sine waves, the output is the sum of the outputs obtained when each of the sine waves is input alone. Considering these two properties, when it is desired to set the output to some periodic function f(t), the Fourier series expansion of f(t) is expressed as the following formula (5). f(t)=A1×cos(2π×f1×t+Φ1) +A2×cos(2π×f2×t+Φ2) +··· ...(5)

[0079] At the input, the same function causes a problem, and "A n " → "A n+1 ", "Φ n " → "Φ n+1 ", it is necessary to appropriately control the amplitude and phase of each frequency component. When it is desired to output "A n_out ", "A n_in " is input.

[0080] The drive device 13 detects the displacement of the movable portion 101 by the detection units 160a, 160b, 160c, and 160d, decomposes the detected displacement into frequency components by FFT processing, and acquires the amplitude and phase of each frequency component.

[0081] The drive control unit 11 determines that for a certain frequency component, when the desired amplitude is A and the phase is Φ, the detected amplitude and phase are A det , Φ det If this is the case, the amplitude of the input signal will be (A / A det The input signal is multiplied by (Φ-Φ) and its phase is set to (Φ-Φ det ) Feedback control such as increasing can be implemented. det This indicates the amplitude of the detected signal. Φ det This indicates the phase of the detected signal.

[0082] In real-time control, correction processing is performed for all frequency components, whereas the drive control unit 11 performs control for each frequency component, allowing for nearly independent control of each frequency component.

[0083] (Drive signal for spiral scanning) Figure 7 shows an example of a drive signal for spiral scanning. In Figure 7, the horizontal axis represents time, and the vertical axis represents the amplitude normalization of the drive waveform. Figure 7 also shows the drive signals applied to drive units 110a, 110b, 110c, and 110d, respectively. The phases of the four drive signals supplied to drive units 110a, 110b, 110c, and 110d are shifted by 90 degrees from each other.

[0084] Next, amplitude modulation in high-speed signal period waveforms will be explained. Figure 8 shows an example of a drive signal with a fundamental period applied to the drive unit 110a. In Figure 8, the horizontal axis represents time, and the vertical axis represents the amplitude normalization amount of the drive waveform. The drive signal in Figure 8 includes a first period Ta, a second period Tb, and a third period Tc in that order within the fundamental period.

[0085] The first period, Ta, is a period in which the amplitude of the drive voltage continuously increases and continues until the amplitude reaches its maximum. The second period, Tb, is a period in which the amplitude of the drive voltage continuously decreases. The third period, Tc, is a period in which the amplitude of the drive voltage is at a predetermined value. The predetermined value of the amplitude in the third period, Tc, is less than or equal to the smallest amplitude value of the second period immediately preceding the third period. In the third period, Tc, the amplitude of the drive voltage may be 0.

[0086] In the example shown in Figure 8, the drive signal includes a first waveform in the first period Ta. The drive signal includes a second waveform in the second period Tb. The drive signal includes a third waveform in the third period Tc. The phases of the first and second waveforms of the drive signals may be in phase or out of phase. The third waveform may be a DC waveform. If the third waveform is a drive waveform with a constant amplitude of drive voltage, its phase may be in phase or out of phase with that of the second waveform.

[0087] It is preferable that the transition in amplitude of the drive waveform from the first period Ta to the second period Tb is continuous. Similarly, it is preferable that the transition in amplitude of the drive waveform from the second period Tb to the third period Tc is continuous. In the first period Ta, the amplitude of the drive waveform increases, the oscillation of the reflector 14 increases, and the energy of the resonant vibration accumulates. In the second period Tb, the amplitude of the drive waveform decreases, and the oscillation of the reflector 14 is attenuated. In the second period Tb, the amplitude of the drive signal input to the first piezoelectric drive unit 112a is smoothly reduced. In the third period Tc, the period in which the amplitude of the drive signal is at a predetermined value continues for a certain time. The certain time is defined as a time of one or more cycles of the high-speed signal period.

[0088] As described above, by providing a drive signal for the fundamental periodic waveform that includes a first waveform whose amplitude continuously increases during the first period Ta, a second waveform whose amplitude continuously decreases during the second period Tb, and a third waveform whose amplitude is a predetermined value during the third period Tc, the oscillation of the reflector 14 toward the center of the field of view O can be attenuated without increasing unnecessary resonance energy during times other than the effective scanning period. Furthermore, when the first period Ta is used as the effective scanning period for projecting the image, a larger resonance energy can be obtained by making the first period Ta longer than the second period Tb, thereby enabling a wider field of view. The effective scanning period refers to the period in which the trajectory of light is drawn when light is irradiated onto the reflector 14.

[0089] Figure 9 shows an example of the ratio of the amplitude increase period to the amplitude decrease period and the ratio of the cavity diameter to the overall field of view of the drive device 13 in the second example. In Figure 9, assuming that the length of the basic period and the length of the first period Ta, which is the amplitude increase period, are constant, the horizontal axis represents the ratio of the length of the first period Ta to the length of the second period Tb, and the vertical axis represents the ratio of the cavity region diameter to the overall field of view.

[0090] When the length of the second period Tb is short, that is, when the length of the third period Tc, where the amplitude is a predetermined value, is long, the ratio of the cavity diameter to the overall field of view is smaller compared to when the length of the second period Tb is long, that is, when the length of the third period Tc is short. "When the length of the fundamental period and the length of the first period Ta are kept constant" means that the ratio of the first period Ta to the fundamental period is constant and does not change.

[0091] When the ratio of the first period Ta to the basic period is constant, shortening the second period Tb and lengthening the third period Tc can increase the resolution, for example, near the image center O1 in the displayed image. This makes it possible to control the resolution of the trajectory of the reflected light from the reflector 14 by changing the ratio of the third period Tc to the basic period.

[0092] (Trajectory of reflected light obtained by spiral scanning) Figure 10 shows an example of the trajectory of reflected light from the reflector 14 when a drive signal for spiral scanning is input. The example shown in Figure 10 shows that when a drive signal for spiral scanning is input, the resolution of the displayed image increases on the image center O1 side compared to when a conventional drive signal is used.

[0093] According to the drive signal for spiral scanning, the amount of oscillation of the movable part 101 converges to be minimized near the image center O1, so that spirals with approximately the same spacing as the spirals in other regions can be drawn near the image center O1. As a result, the diameter of the cavity at the image center O1 can be reduced, and the resolution of the image displayed on the illuminated surface using the light reflected by the reflector 14 can be increased.

[0094] The drive signal for the basic period includes a first waveform whose amplitude continuously increases during the first period Ta, a second waveform whose amplitude continuously decreases during the second period Tb following the first period Ta, and a third waveform whose amplitude is a predetermined value during the third period Tc following the second period Tb. The predetermined value for the amplitude of the third waveform is set to be less than or equal to the smallest amplitude value of the second waveform in the second period immediately preceding the third period.

[0095] In the drive device 13, by applying a drive signal including the third waveform to the drive units 110a, 110b, 110c, and 110d, the amount of oscillation of the movable part 101 can be made smaller than at the end of the second period Tb. The drive device 13 can further reduce the oscillation of the movable part 101. As a result, the amount of mirror oscillation returns to the field of view 0 within one period of the basic period, and thus the resolution on the image center O1 side can be increased.

[0096] In the third period Tc, the amplitude of the third waveform is a predetermined value, and this predetermined value may be less than or equal to the smallest amplitude value of the second waveform in the second period Tb immediately preceding the third period Tc. As shown in Figure 9, in the drive waveform according to the first embodiment, the amplitude of the third waveform in the third period Tc is less than or equal to the smallest amplitude value of the second waveform in the second period Tb. By setting the amplitude of the third waveform to less than or equal to the smallest amplitude value of the second waveform in the second period immediately preceding the third period, the oscillation of the movable part 101 can be reduced more efficiently.

[0097] The third waveform may be a DC waveform or have an amplitude of 0. By making the third waveform a DC waveform or having an amplitude of 0, the oscillation of the movable part 101 can be reduced more efficiently.

[0098] The length of the second period Tb is preferably shorter than the length of the first period Ta. In other words, the length of the first period Ta is preferably longer than the length of the second period Tb. In the drive waveform according to the first embodiment, the first period Ta is longer than the second period Tb.

[0099] <Method for correcting the drive signal by the drive control unit 11> Next, the method for correcting the drive signal by the drive control unit 11 will be described.

[0100] For example, in a typical drive system, if the drive signal contains multiple frequency components, the control accuracy of the drive unit may be reduced due to the influence of the combined frequency generated by nonlinear effects. To address this, one could measure characteristic values ​​such as the resonant frequency or nonlinear coefficient and correct the influence of the combined frequency based on the measurement results. However, repeatedly measuring characteristic values ​​while the drive system is operating results in long waiting times each time, which is undesirable from the perspective of user experience. This is especially undesirable when the ambient temperature of the drive system changes, as the above characteristic values ​​fluctuate according to the ambient temperature, requiring repeated measurements.

[0101] In the drive unit 13, the drive control unit 11 corrects the frequency components included in the drive signal based on the combined frequency component of multiple frequency components decomposed from the detection signal by the detection units 160a, 160b, 160c, and 160d. For example, the drive control unit 11 corrects the input amplitude of a frequency component by searching for the most appropriate value as the input amplitude of the frequency component included in the drive signal through multiple drives, without measuring characteristic values ​​such as the resonant frequency or nonlinear coefficient. This allows for accurate control of the drive units 110a, 110b, 110c, and 110d using a drive signal containing multiple frequency components. Compared to a method of correction based on the measurement results of characteristic values ​​such as the resonant frequency or nonlinear coefficient, this method eliminates the need for repeated measurements, thus efficiently correcting the input amplitude of frequency components and is preferable from the viewpoint of user experience. In the drive unit 13, the combined frequency component refers to the frequency component obtained by combining multiple frequency components decomposed from the detection signal by the detection units 160a, 160b, 160c, and 160d.

[0102] In the drive unit 13, the drive control unit 11 can control the drive units 110a, 110b, 110c, and 110d using the respective drive signals of a plurality of drive signals whose combined frequency components have different amplitudes. Furthermore, the drive control unit 11 can correct the frequency components included in the drive signals based on the combined frequency components decomposed from the detection signal corresponding to each of the plurality of drive signals. As a result, even when the drive signal contains multiple frequency components, the drive unit 13 can correct the influence of the combined frequency generated by nonlinear effects and accurately control the drive units 110a and 110b using a drive signal containing multiple frequency components.

[0103] The drive control unit 11 can also correct the frequency components included in the drive signal based on the amplitude of the composite frequency component in the drive signal when the amplitude of the composite frequency component decomposed from the detection signal is minimized among multiple drive signals. In this case as well, the drive device 13 can correct the influence of the composite frequency generated by nonlinear effects, even when the drive signal contains multiple frequency components, and can accurately control the drive units 110a and 110b using a drive signal containing multiple frequency components.

[0104] Furthermore, the drive control unit 11 may correct all frequency components of the drive signal, or it may correct only some of the frequency components. When all frequency components are corrected, the drive unit is controlled most precisely. On the other hand, when only some frequency components are corrected, the time required for correction and the memory needed for calculation can be reduced. When only some frequency components are corrected, the fewer frequency components to correct, the less calculation time and memory is required. Depending on the application, it is necessary to select the frequency components to be corrected according to the allowable correction time. Here, among the composite frequency components included in the detection signal, those with large amplitudes contribute significantly to the control error of the drive unit. Therefore, when correcting only some frequency components, the amplitude of the composite frequency components included in the detection signal can be used as the selection criterion for the composite frequency components to be corrected, and the top N components with the largest amplitudes can be selected.

[0105] The composite frequency component to be corrected is determined in advance during the design phase, and the frequency information is stored beforehand. In addition, it is desirable to include the stored composite frequency component as an appropriate amplitude in the drive signal that controls the drive unit. By doing so, when performing the method of this patent, the correction is performed from a state close to the appropriate drive signal, thus reducing the time required for correction.

[0106] (Example of correction method 1) A specific example of a method for correcting the drive signal by the drive device 13 will be described. First, Figure 11 is a diagram illustrating a first example of a method for correcting the drive signal by the drive device 13.

[0107] In Figure 11, the horizontal axis represents the input amplitude A_in_i of the frequency component of interest, and the vertical axis represents the detected amplitude A_out_i of the frequency component of interest. Figure 11 shows a method for searching for the input amplitude A_in_i of the drive signal to the drive units 110a, 110b, 110c, and 110d that minimizes the detected amplitude A_out_i of the composite frequency component decomposed from the detected signal. In the first example shown in Figure 11, the white circle plots represent the detected amplitude A_out_i of vibration signals that are not the minimum. The black circle plots represent the detected amplitude A_out_i of vibration signals that are the minimum. In addition, the notations "i=0", "i=1", etc. in the vicinity of each plot indicate the i-th input amplitude A_in_i out of multiple input amplitudes A_in_i that are changed. The same applies to the second example of the correction method shown in Figure 12 and the third example of the correction method shown in Figure 13.

[0108] In the first example shown in Figure 11, the drive control unit 11 searches for the input amplitude A_in_i that minimizes the detected amplitude A_out_i by changing the input amplitude A_in_i multiple times within a predetermined search range. Assuming i is a natural number, the absolute value of the change in the input amplitude A_in_i when the drive control unit 11 changes it for the (i+1)th time is smaller than the absolute value of the change in the input amplitude A_in_i when it changes it for the (i)th time. Also, the absolute value of the change in the input amplitude A_in_i when the drive control unit 11 changes it for the (i+2)th time is smaller than the absolute value of the change in the input amplitude A_in_i when it changes it for the (i+1)th time.

[0109] In the example shown in Figure 11, the plot for i=0, which corresponds to the initial value of the input amplitude A_in_i, represents the input amplitude A_in_i for the 0th time. When the input amplitude A_in_i is set to 0, the detected amplitude A_out_i is not 0. The plot for i=1 represents the input amplitude A_in_i for the 1st time. The plot for i=2 represents the input amplitude A_in_i for the 2nd time. The plot for i=3 represents the input amplitude A_in_i for the 3rd time.

[0110] The absolute value of the change in input amplitude A_in_i from the 1st to the 2nd time is smaller than the absolute value of the change in input amplitude A_in_i from the 0th to the 1st time. The absolute value of the change in input amplitude A_in_i from the 2nd to the 3rd time is smaller than the absolute value of the change in input amplitude A_in_i from the 1st to the 2nd time. In the example shown in Figure 11, the change in input amplitude A_in_i is repeated 7 times, and at the 7th time (i=7), the input amplitude A_in_i that minimizes the detected amplitude A_out_i has been found.

[0111] In the first example of the correction method, as the number of times the input amplitude A_in_i is changed increases, the absolute value of the change in the input amplitude A_in_i is reduced, allowing the search to gradually narrow down the input amplitude A_in_i that minimizes the detected amplitude A_out_i. As a result, in the first example of the correction method, changes in the input amplitude A_in_i that are wasted during the search are suppressed, reducing the number of changes in the input amplitude A_in_i and making it easier to find the input amplitude A_in_i that minimizes the detected amplitude A_out_i in a short time. In addition, in the first example of the correction method, it is not necessary to associate the input amplitude A_in_i with the detected amplitude A_out_i and store them in memory each time the input amplitude A_in_i is changed. Therefore, it is easier to reduce the memory capacity required in the search for the input amplitude A_in_i that minimizes the detected amplitude A_out_i.

[0112] (Second example of correction method) Figure 12 illustrates a second example of a method for correcting the drive signal by the drive device 13.

[0113] In the second example shown in Figure 12, the change in the input amplitude A_in_i is constant regardless of the number of times the input amplitude A_in_i is changed, which is different from the first example of the correction method.

[0114] In the example shown in Figure 12, the input amplitude A_in_i is changed by a constant range from the 0th time (i=0) to the 7th time (i=7). In the second example of the correction method, the drive control unit 11 stores the input amplitude A_in_i and the detected amplitude A_out_i information in a memory device, associating them with each other, each time the input amplitude A_in_i is changed. The drive control unit 11 reads the input amplitude A_in_i and the detected amplitude A_out_i from the memory device and, based on the read information, can determine the input amplitude A_in_i that minimizes the detected amplitude A_out_i.

[0115] In the second example of the correction method, the input amplitude A_in_i is varied by a constant range to cover the entire predetermined search range. This ensures that the input amplitude A_in_i that minimizes the detected amplitude A_out_i is reliably searched for within the search range. Furthermore, reducing the range of change of the input amplitude A_in_i improves the accuracy of finding the input amplitude A_in_i that minimizes the detected amplitude A_out_i.

[0116] (Third example of correction method) Figure 13 illustrates a third example of a method for correcting the drive signal by the drive device 13.

[0117] In the third example of the correction method, the drive control unit 11 determines the input amplitude A_in_i when the detected amplitude A_out_i is minimized, using either interpolation or extrapolation, in the change interval where the detected amplitude A_out_i is minimized, among a plurality of change intervals in which the detected amplitude A_out_i changes in accordance with the change range of the input amplitude A_in_i. This point differs from the first example of the correction method.

[0118] In the example shown in Figure 13, the intersection point of the first approximation line La1, which is obtained by linearly approximating the plots i=0, i=1, and i=4, and the second approximation line La2, which is obtained by linearly approximating the plots i=2, i=3, and i=4, is found. This intersection point corresponds to the input amplitude A_in_i when the detected amplitude A_out_i is minimized. In other words, in the example shown in Figure 13, the input amplitude A_in_i when the detected amplitude A_out_i is minimized is found by interpolation to find the intersection point of the first approximation line La1 and the second approximation line La2.

[0119] In the third example of the correction method, even without reducing the range of change in the input amplitude A_in_i, the search accuracy for the input amplitude A_in_i that minimizes the detected amplitude A_out_i can be improved through interpolation. This makes it easier to achieve both improved search accuracy and reduced search time in the third example of the correction method. Note that the interpolation method is not limited to the method using the intersection of the approximate lines described above, but various methods can be applied. Also, in the third example of the correction method, extrapolation may be performed instead of interpolation. In this case as well, the above effects can be obtained.

[0120] The drive control unit 11 can also determine the input amplitude A_in_i when the detected amplitude A_out_i is minimized by using an approximation formula that represents the relationship between the input amplitude A_in_i and the detected amplitude A_out_i. For example, as illustrated in the third example of the correction method, the drive control unit 11 can calculate the input amplitude A_in_i when the detected amplitude A_out_i is minimized by using an approximation line that represents the relationship between the input amplitude A_in_i and the detected amplitude A_out_i. Furthermore, the drive control unit 11 can calculate the input amplitude A_in_i when the detected amplitude A_out_i is minimized not only by linear approximation, but also by logarithmic approximation or polynomial approximation. As described above, the drive device 13 can easily achieve both improved search accuracy and reduced search time by using an approximation formula that represents the relationship between the input amplitude A_in_i and the detected amplitude A_out_i.

[0121] The drive control unit 11 can also perform the following first and second drive controls. The first drive control controls the drive units 110a, 110b, 110c, and 110d by the drive signals of a plurality of drive signals, each having a different amplitude of combined frequency components, without reflecting light with the reflector unit 14, and corrects the frequency components included in the drive signals based on the combined frequency components decomposed from the detection signal corresponding to each of the plurality of drive signals. The second drive control controls the drive units 110a, 110b, 110c, and 110d by reflecting light with the reflector unit 14 and using the drive signals.

[0122] For example, the first control is a control that the drive device 13 can execute based on the detection signals of the deformation of the drive beams 113a, 113b, 113c, and 113d by the detection units 160a, 160b, 160c, and 160d. The second control is a control that the drive device 13 can execute based on the detection signals of the reflected light position by the detection units 160a, 160b, 160c, and 160d, which are positioned to receive reflected light from the reflector 14 of the movable part 101. Depending on the intended use of the drive device 13, the drive device 13 can select and perform either the first control or the second control, whichever is easier to control. This makes it easier for the drive device 13 to perform control. Furthermore, depending on the intended use of the drive device 13, the drive device 13 can execute both the first control and the second control. This makes it easier for the drive device 13 to improve control accuracy.

[0123] (Correction processing by the drive control unit 11) Figure 14 is a flowchart showing an example of the drive signal correction process performed by the drive control unit 11. The drive unit 13 starts the correction process shown in Figure 14 when predetermined start conditions are met. The predetermined start conditions are, for example, when an operator of the drive unit 13 inputs an operation to start the correction via the operation unit of the drive unit 13, and the drive unit 13 receives the operation input. Alternatively, the predetermined start conditions may be when the drive unit 13 is started up or when a predetermined timing is reached.

[0124] First, in step S11, the drive control unit 11 applies drive signals to the drive units 110a and 110b via the drive signal output unit 32. The application of drive signals to the drive units 110a, 110b, 110c, and 110d causes the movable part 101 to be displaced. The detection units 160a, 160b, 160c, and 160d detect the displacement of the movable part 101 and output a detection signal to the drive control unit 11.

[0125] Next, in step S12, the drive control unit 11 performs FFT processing on the detection signals input from the detection units 160a, 160b, 160c, and 160d. The drive control unit 11 can obtain the detection amplitude from the FFT processing result.

[0126] Next, in step S13, the drive control unit 11 determines whether the detected amplitude of the frequency component appearing due to the nonlinear effect is below a predetermined threshold. Information identifying the frequency component appearing due to the nonlinear effect and information regarding the threshold are predetermined and stored in ROM 22 or the like. The drive control unit 11 compares the threshold read from ROM 22 or the like with the detected amplitude of the frequency component identified by the information identifying the frequency component appearing due to the nonlinear effect obtained in step S12. This allows the drive control unit 11 to determine whether the detected amplitude of the frequency component appearing due to the nonlinear effect is below a predetermined threshold.

[0127] If it is determined in step S13 that the value is not below a predetermined threshold, the drive control unit 11 corrects the drive signal in step S14. The drive control unit 11 may use the first example shown in Figure 11, the second example shown in Figure 12, or the third example shown in Figure 13 as a method for correcting the drive signal. After the correction is completed, the drive control unit 11 repeats the process from step S11 onwards. The drive control unit 11 repeats the process from step S11 onwards until it is determined in step S13 that the value is below a predetermined threshold.

[0128] On the other hand, if it is determined in step S13 that the value is below a predetermined threshold, the drive control unit 11 terminates the process.

[0129] As described above, the drive control unit 11 can perform correction processing on the drive signal. If there are multiple frequency components that appear due to nonlinear effects, the drive control unit 11 may perform the processing shown in Figure 14 multiple times for each of the multiple frequency components.

[0130] <Correction result of drive signal by drive device 13> Figure 15A shows an example of a drive signal that has not been corrected by the drive device 13. Figure 15B shows an example of the displacement of the movable part 101 driven by the drive signal shown in Figure 15A. Figure 15C shows an example of a drive signal that has been corrected by the drive device 13. Figure 15D shows an example of the displacement of the movable part 101 driven by the drive signal shown in Figure 15C.

[0131] As shown in Figure 15A, when an uncorrected drive signal is applied, as the voltage increases, the voltage value of the detection signal becomes higher than the ideal peak voltage value near the peak of the envelope graph shown by the dashed line, as shown in Figure 15B.

[0132] On the other hand, when a corrected drive signal was applied, as shown in Figure 15C, the voltage value decreased near the peak of the drive signal. Furthermore, the peak voltage value of the comprehensive line graph for the detection signal shown in Figure 15D almost coincided with the peak voltage value of the comprehensive line graph for the drive signal shown in Figure 15C. From this, it was found that applying a corrected drive signal provides a soft spring effect in which the restoring force decreases when the displacement of the movable part 101 is large. It was also found that the drive parts 110a, 110b, 110c, and 110d can be controlled with high precision due to the soft spring effect.

[0133] <Optical scanning system 10> Next, an optical scanning system 10 equipped with a drive device 13 will be described. Figure 16 is a schematic diagram of an example of an optical scanning system. The optical scanning system 10 is a system that optically scans the surface to be scanned 15 by deflecting light emitted from a light source device 12. The drive device 13 may be either the drive device 13 according to the first example or the drive device 13 according to the second example. Note that in the description of the optical scanning system 10, explanations similar to those of the above embodiments may be omitted.

[0134] The optical scanning system 10 comprises a drive control unit 11, a light source device 12, and a drive device 13. The drive device 13 may include the drive control unit 11 and the light source device 12.

[0135] The drive control unit 11 is an electronic circuit unit equipped with, for example, a CPU and an FPGA. The drive device 13 includes a movable part 101. The movable part 101 includes a reflector 14. The drive device 13 is a MEMS device that drives the movable part 101.

[0136] The light source device 12 is, for example, a laser device that emits a laser. The scanning surface 15 is, for example, a screen.

[0137] The drive control unit 11 outputs a drive signal to the light source device 12 or the drive device 13 based on the input control signal. The drive signal is a signal for controlling the drive of the light source device 12 or the drive device 13. For example, the drive signal output to the light source device 12 is a drive voltage that controls the irradiation timing and irradiation intensity of the light source. The drive signal output to the drive device 13 is a drive voltage that controls the timing and range of movement of the reflector 14.

[0138] The drive control unit 11 generates control commands for the light source device 12 and the drive device 13 based on the acquired optical scanning information. Based on the control commands, the drive control unit 11 outputs drive signals to the light source device 12 and the drive device 13. The light source device 12 emits light from the light source based on the input drive signals. The drive device 13 can swing the reflector 14 around the X axis based on the input drive signals. The drive device 13 can swing the reflector 14 around the Y axis based on the input drive signals. The drive device 13 may also swing the reflector 14 around axes extending in other directions.

[0139] The optical scanning system 10 can perform optical scanning by oscillating the reflective section 14, thereby projecting the light reflected by the reflective section 14 onto the surface to be scanned 15. The optical scanning system 10 can project any image onto the surface to be scanned 15.

[0140] (A process that involves optical scanning) Next, the process by which the optical scanning system 10 optically scans the surface to be scanned 15 will be described. Figure 17 is a flowchart of an example of the processing procedure performed in the optical scanning system 10.

[0141] In step S11, the control unit 30 acquires optical scanning information from an external device or the like. 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 32. In step S13, the drive signal output unit 32 outputs a drive signal to the light source device 12 and the first piezoelectric drive units 112a, 112b, 112c, and 112d of the drive device 13 based on the input control signal. In step S14, the light source device 12 irradiates light based on the input drive signal. The first piezoelectric drive units 112a, 112b, 112c, and 112d of the drive device 13 also oscillate the reflector 14 based on the input drive signal. According to the optical scanning system 10, the light is deflected in any direction and optical scanning is performed by driving the light source device 12 and the drive device 13.

[0142] The optical scanning system 10 may also include a drive control unit 11 that controls the first piezoelectric drive units 112a, 112b, 112c, and 112d of the drive device 13, and a control device that controls the light source device 12, separately.

[0143] The optical scanning system 10 can suppress the decrease in the resonant frequency that occurs when the movable part 101 is enlarged. The optical scanning system 10 can perform optical scanning with high precision.

[0144] [Second Embodiment] Next, a head-up display device according to the second embodiment will be described. Figure 18 is a schematic diagram of an example of an automobile 400 equipped with a head-up display device 500. The head-up display device 500 is equipped with a drive unit 13. The automobile 400 is equipped with the head-up display device 500. The head-up display device 500 is an image projection device that projects images by optical scanning. The automobile 400 is an example of a mobile device.

[0145] As shown in Figure 18, the head-up display device 500 is installed, for example, near the windshield (windshield 401, etc.) of a car 400. Projected light L emitted from the head-up display device 500 is reflected by the windshield 401 and directed towards the user, the observer (driver 402). As a result, the driver 402 can see the image projected by the head-up display device 500 as a virtual image. Alternatively, a combiner may be installed on the inner wall surface of the windshield, and the virtual image may be seen by the user by the projected light reflected by the combiner.

[0146] Figure 19 is a schematic diagram showing an example of a head-up display device 500. The head-up display device 500 is equipped with laser light sources 501R, 501G, and 501B. Laser light source 501R emits red laser light. Laser light source 501G emits green laser light. Laser light source 501B emits blue laser light.

[0147] The head-up display device 500 includes an incident optical system. The incident optical system includes collimator lenses 502, 503, and 504, two dichroic mirrors 505 and 506, and a light intensity adjustment unit 507. The collimator lenses 502 to 504 are provided for laser light sources 501R, 501G, and 501B. Laser light emitted from the laser light sources 501R, 501G, and 501B passes through the incident optical system and enters the drive unit 13. The laser light that enters the drive unit 13 is reflected by the reflector unit 14. The laser light is deflected by the drive unit 13.

[0148] The head-up display device 500 includes a projection optical system. The projection optical system includes a free-form surface mirror 509, an intermediate screen 510, and a projection mirror 511. The laser light deflected by the drive device 13 is projected onto the windshield 401 via the projection optical system. The head-up display device 500 may project the laser light onto a screen. The head-up display device 500 may also include a unitized light source unit 530 with an optical housing. The optical housing may house, for example, laser light sources 501R, 501G, 501B, collimator lenses 502, 503, 504, and dichroic mirrors 505, 506.

[0149] The head-up display device 500 can project the intermediate image displayed on the intermediate screen 510 onto the windshield 401. According to the head-up display device 500, the intermediate image projected onto the windshield 401 can be viewed by the driver 402 as a virtual image.

[0150] The laser light of each color emitted from the laser light sources 501R, 501G, and 501B is made into approximately parallel light by collimator lenses 502, 503, and 504, respectively, and then combined by two dichroic mirrors 505 and 506. The dichroic mirrors 505 and 506 may each be examples of the combining section. After the combined laser light is adjusted in light intensity by the light intensity adjustment section 507, it is scanned in two dimensions by the drive unit 13. The projected light L scanned in two dimensions by the drive unit 13 is reflected by a free-form mirror 509 to correct distortion, and then focused onto the intermediate screen 510. The intermediate screen 510 displays an intermediate image. The intermediate screen 510 is composed of a microlens array in which microlenses are arranged in two dimensions. The intermediate screen 510 magnifies the incident projected light L in units of microlenses.

[0151] The drive unit 13 causes the reflecting section 14 to oscillate (reciprocate) in two axial directions. The drive unit 13 scans the projected light L incident on the reflecting section 14 in two dimensions. The drive control of the drive unit 13 is synchronized with the light emission timing of the laser light sources 501R, 501G, and 501B.

[0152] The image projection device can project an image by performing an optical scan using a drive unit 13 equipped with a reflective section 14. The image projection device may be, for example, a projector placed on a desk or the like that projects an image onto a display screen.

[0153] The image projection device is not limited to those mounted on a vehicle or mounting member. For example, the image projection device may be mounted on a moving object such as an aircraft, ship, or mobile robot. Alternatively, the image projection device may be mounted on a non-moving object such as a work robot that operates a drive target such as a manipulator without moving from its location.

[0154] The image projection device equipped with the drive unit 13 can precisely control the drive units 110a and 110b using a drive signal containing multiple frequency components, enabling high-precision optical scanning.

[0155] [Third Embodiment] Next, an optical writing device according to the third embodiment will be described. Figure 20 is a schematic diagram showing an example of an image forming apparatus 610 equipped with an optical writing device 600. The image forming apparatus 610 includes a drive unit 13. The image forming apparatus 610 may also be a laser printer 650. The laser printer 650 has a printer function using laser light. The laser printer 650 includes an optical writing device 600. The optical writing device 600 optically scans the photoreceptor drum, which is the scanning surface 15, with one or more laser beams. The optical writing device 600 performs optical writing on the photoreceptor drum by optical scanning. The optical writing device 600 includes a drive unit 13.

[0156] Figure 21 is a schematic diagram showing an example of an optical writing device 600. In the optical writing device 600, the laser light emitted from the light source device 12, such as a laser element, passes through the imaging optical system 601, such as a collimator lens, and is then deflected in one axis direction or two axis directions by the drive device 13.

[0157] The optical writing device 600 includes a scanning optical system 602. The scanning optical system includes a first lens 602a, a second lens 602b, and a reflective mirror section 602c. The laser light deflected by the drive device 13 passes through the scanning optical system 602 and is irradiated onto the surface to be scanned 15 (for example, a photosensitive drum or photosensitive paper). As a result, the optical writing device 600 performs optical writing on the surface to be scanned 15. The scanning optical system 602 forms a spot-shaped image of the light beam on the surface to be scanned 15. As described above, the drive control unit 11 applies drive signals to the drive units 110a, 110b, 110c, and 110d of the drive device 13 to oscillate the reflective section 14.

[0158] Thus, the optical writing device 600 can be applied to an image forming apparatus 610 equipped with a laser light printer function. The image forming apparatus 610 equipped with the optical writing device 600 may also be a laser labeling apparatus. The optical writing device 600 may be mounted on an image forming apparatus such as a laser labeling apparatus that has a scanning optical system capable of optical scanning in two axes, and prints by deflecting laser light onto a thermal media, optical scanning, and heating.

[0159] The drive unit 13 equipped with the reflective section 14 consumes less power for driving compared to a rotating polyhedron mirror using a polygon mirror or the like. The optical writing device 600 equipped with the drive unit 13 allows for power saving. The wind noise generated by the drive unit 13 during vibration is less than that of a rotating polyhedron mirror. Therefore, the optical writing device 600 equipped with the drive unit 13 allows for improved quietness. The installation space required for the drive unit 13 is significantly less than that required for a rotating polyhedron mirror. The heat generated by the drive unit 13 is significantly less than that of a rotating polyhedron mirror. The image forming apparatus equipped with the optical writing device 600 allows for easy miniaturization of the entire apparatus.

[0160] Thus, by applying the drive device 13 of the embodiment to the optical writing device 600, the drive units 110a and 110b can be controlled with high precision using a drive signal containing multiple frequency components, and an optical writing device capable of high-precision optical scanning can be provided.

[0161] [Fourth Embodiment] [Laser radar device 700] Next, a laser radar device 700 according to the fourth embodiment will be described. Figures 22 and 23 are schematic diagrams of an example of an automobile 701 equipped with a laser radar device 700. Figure 24 is a schematic diagram of an example of a laser radar device 700. The laser radar device 700 is equipped with a drive unit 13. The laser radar device 700 is a distance measuring device that measures the distance to an object in the target direction. A distance measuring device is an example of an object recognition device. The laser radar device 700 is equipped with a drive unit 13. The laser radar device 700 is mounted on an automobile 701, for example, and measures the distance to an object 702 by optically scanning the target direction and receiving reflected light from an object 702 present in the target direction. The automobile 701 is an example of a mobile body.

[0162] As shown in Figure 24, the laser radar device 700 includes an incident optical system. The incident optical system includes a collimator lens 703 and a plane mirror 704. The collimator lens 703 is an optical system that converts divergent light into approximately parallel light. The laser light emitted from the light source device 12 passes through the incident optical system and is scanned in one or two axes by the drive device 13.

[0163] The laser radar device 700 includes a light projection optical system equipped with a light projection lens 705. Light reflected by the reflector 14 of the drive unit 13 passes through the light projection lens 705 and is projected onto the target object 702 in front. The drive control unit 11 drives and controls the light source device 12 and the drive unit 13. The reflected light reflected by the target object 702 is detected by the photodetector 709. The reflected light is received by the image sensor 707 via the incident light detection and reception optical system, such as the condensing lens 706. The image sensor 707 outputs the detection signal to the signal processing device 708. The signal processing device 708 performs predetermined processing on the input detection signal, such as binarization and noise processing, and outputs the result to the distance measuring circuit 710.

[0164] The distance measuring circuit 710 recognizes the presence or absence of the object 702 based on the time difference between the timing when the light source device 12 emits laser light and the timing when the photodetector 709 receives the laser light, or the phase difference of each pixel of the image sensor 707 that receives the light, and calculates distance information to the object 702.

[0165] The drive unit 13, equipped with the reflective section 14, is less prone to damage and smaller than a multifaceted mirror, thus enabling the provision of a highly durable, compact radar device. Such a radar device can be mounted on vehicles, aircraft, ships, robots, etc., and can optically scan a predetermined range to measure the presence or absence of obstacles and the distance to those obstacles.

[0166] The distance measuring device performs optical scanning by controlling a drive unit 13 equipped with a reflector 14 with a drive control unit 11, and measures the distance to the target object 702 by receiving the reflected light with a photodetector. The object recognition device is not limited to the distance measuring device. The object recognition device only needs to be able to detect the target object 702 by being equipped with a drive unit 13, performing optical scanning, and receiving the reflected light with a photodetector.

[0167] The object recognition device may be, for example, a biometric authentication device that recognizes an object by calculating object information such as shape from distance information obtained by optical scanning of a hand or face, and then recording and referencing this information. The object recognition device may also be a security sensor that recognizes intruders by optical scanning within a target area. The object recognition device may also be a 3D scanner that calculates and recognizes object information such as shape from distance information obtained by optical scanning and outputs it as 3D data.

[0168] By including a drive unit 13, such a distance measuring device can accurately control the drive units 110a and 110b using a drive signal containing multiple frequency components, enabling high-precision optical scanning.

[0169] [Fifth Embodiment] Next, a laser headlamp according to the fifth embodiment will be described. Figure 25 is a schematic diagram showing an example of a laser headlamp 50. The laser headlamp 50 includes a drive unit 13. The laser headlamp 50 may also be a headlight for an automobile. The laser headlamp 50 includes a light source device 12b, a drive unit 13, a mirror 51, and a transparent plate 52. The laser headlamp 50 includes a drive control unit 11, which is a control unit.

[0170] The light source device 12b is a light source that emits blue laser light. The light emitted from the light source device 12b is incident on the drive device 13 and reflected by the reflector 14. The drive units 110a to 110d of the drive device 13 oscillate the reflector 14 based on signals from the drive control unit 11. The drive device 13 oscillates the reflector 14 to scan the laser light in two dimensions in the X and Y directions.

[0171] The scanning light from the drive unit 13 is reflected by the mirror 51 and incident on the transparent plate 52. The transparent plate 52 is coated on either its front or back surface with a yellow phosphor. The blue laser light reflected by the mirror 51 changes to white light within the range legally defined for headlights as it passes through the yellow phosphor coating on the transparent plate 52. As a result, the area in front of the vehicle equipped with the laser headlamp 50 is illuminated with white light.

[0172] The scanning light from the drive unit 13 undergoes a predetermined scattering as it passes through the phosphor in the transparent plate 52. This reduces glare on the illuminated object in front of the vehicle.

[0173] In the laser headlamp 50, the colors of the light source device 12b and the phosphor are not limited to blue and yellow, respectively. The laser headlamp 50 may also include a light source device 12b that emits near-ultraviolet light. In the laser headlamp 50, the transparent plate 52 may be covered with a uniform mixture of blue, green, and red phosphors, which are the three primary colors of light. With this configuration, the light passing through the transparent plate 52 can be converted to white light, and the area in front of the vehicle can be illuminated with white light.

[0174] By including a drive unit 13, such a laser headlamp 50 can precisely control the drive units 110a and 110b using a drive signal containing multiple frequency components, enabling high-precision optical scanning.

[0175] [Sixth Embodiment] Next, a head-mounted display according to the sixth embodiment will be described. Figure 26 is a perspective view showing an example of a head-mounted display 60. Figure 26 is a schematic cross-sectional view partially illustrating the head-mounted display 60. The head-mounted display 60 includes a drive unit 13. The head-mounted display 60 is a head-mounted display that can be worn on a human head. The head-mounted display 60 can be shaped, for example, like eyeglasses. Hereinafter, the head-mounted display may be abbreviated as HMD.

[0176] The HMD60 comprises a front 60a and temples 60b, each provided in a roughly symmetrical arrangement on the left and right sides. The front 60a includes, for example, a light guide plate 61. The temples 60b can house an optical system, a drive control unit 11, and the like.

[0177] Figure 27 shows the left eye portion of the HMD60. The right eye portion of the HMD60 has the same configuration as the left eye portion. The HMD60 comprises a light source unit 530, a light intensity adjustment unit 507, a drive device 13, a light guide plate 61, and a half mirror 62. The drive device 13 may also include a drive control unit 11 as a control unit.

[0178] As described above, the light source unit 530 is unitized by an optical housing. The light source unit 530 may also be the light source device 12. As shown in Figure 27, the light source unit 530 houses the laser light sources 501R, 501G, and 501B, the collimator lenses 502, 503, and 504, and the dichroic mirrors 505 and 506. In the light source unit 530, the three colors of laser light emitted from the laser light sources 501R, 501G, and 501B are combined by the dichroic mirrors 505 and 506. The light source unit 530 emits the combined parallel light.

[0179] Light emitted from the light source unit 530 is adjusted in intensity by the light intensity adjustment unit 507 before being incident on the drive unit 13. The drive unit 13 oscillates the reflector unit 14 based on the drive signal input from the drive control unit 11. The drive unit 13 performs a two-dimensional scan of the light incident on from the light source unit 530. The drive control unit 11 drives and controls the first piezoelectric drive units 112a, 112b, 112c, and 112d of the drive unit 13 in synchronization with the light emission timing of the laser light sources 501R, 501G, and 501B. The HMD 60 forms a color image using the scanning light.

[0180] As shown in Figure 27, scanning light from the drive unit 13 is incident on the light guide plate 61. The light guide plate 61 guides the scanning light to the half mirror 62 while reflecting it off its inner wall surface. The light guide plate 61 is made of a resin or the like that is transparent to the wavelength of the scanning light.

[0181] The half-mirror 62 reflects light from the light guide plate 61 to the back side of the HMD 60 and emits it towards the eyes of the wearer 63. The half-mirror 62 has, for example, a free-form surface shape. The image formed by the scanning light is projected onto the wearer's retina by reflection from the half-mirror 62. Alternatively, the HMD 60 projects onto the wearer's retina by reflection from the half-mirror 62 and the lens effect of the crystalline lens in the eyeball. In the HMD 60, spatial distortion in the image is corrected by reflection from the half-mirror 62. The wearer 63 can observe the image formed by light scanned in the XY direction.

[0182] By equipping the HMD60 with a half-mirror 62, the wearer 63 can observe an image in which the image from light from the outside and the image from scanning light are superimposed. The HMD60 may also be equipped with a mirror instead of the half-mirror 62. With this configuration of the HMD60, by eliminating light from the outside, the wearer 63 can observe only the image from scanning light.

[0183] In this way, by applying the drive device 13 of the embodiment to a head-mounted display, the decrease in resonant frequency that occurs when increasing the size of the movable part can be suppressed, and a head-mounted display capable of high-precision optical scanning can be provided.

[0184] By incorporating a drive unit 13, such an HMD60 can precisely control the drive units 110a and 110b using a drive signal containing multiple frequency components, enabling high-precision optical scanning.

[0185] [Seventh Embodiment] Next, an eyeball tilt position detection device according to the seventh embodiment will be described. Figure 28 is a schematic configuration diagram showing an example of an eyeball tilt position detection device 80. The eyeball tilt position detection device 80 is equipped with a drive device 13. The eyeball tilt position detection device is a pupil or corneal position detection device 80 that detects the position of the pupil or cornea.

[0186] In this embodiment, the "tilt position of the eyeball" refers to the position of the pupil or cornea of ​​the eyeball, or the direction of the user's gaze. Hereafter, the "tilt position of the eyeball" will be described as the position of the pupil or cornea, and the "eyeball tilt position detection device" will be described as the "pupil or cornea position detection device." Furthermore, the pupil or cornea position detection device described below is synonymous with a gaze direction tracking device (eye tracking device) that detects or tracks the user's gaze direction continuously or at time intervals.

[0187] The pupil or corneal position detection device 80 shown in Figure 28 comprises a light source 82, a first light deflection unit 83, a drive unit 13, a second light deflection unit 85, and a light receiving unit 86. The light source 82 may be a light source device 12. The pupil or corneal position detection device 80 may also include a drive control unit 11.

[0188] The light source 82 includes, for example, laser light sources 82r, 82g, and 82b that emit red, green, and blue laser light, and an infrared laser light source 82ir that emits infrared laser light. The laser light sources 82r, 82g, and 82b may be any one or any combination of two. The laser light sources 82r, 82g, and 82b emit light for drawing an image by the drive device 13.

[0189] The infrared laser light source 82ir emits light for detecting the position of the pupil or cornea. The light used to detect the position of the pupil or cornea is not limited to infrared light; visible light may also be used. From the viewpoint of improving the visibility of the drawn image, invisible light is preferred for detecting the position of the pupil or cornea.

[0190] The first light deflection unit 83 is, for example, a dichroic mirror, and deflects the light emitted from the light source 82 toward the reflector unit 14 of the drive unit 13 while combining the light. The pupil or corneal position detection device 80 may include a plurality of first light deflection units 83-1, 83-2, 83-3, 83-4, 83-5 depending on the number of laser light sources 82r, 82g, 82b and infrared laser light sources 82ir. The first light deflection unit 83 includes a plurality of first light deflection units 83-1, 83-2, 83-3, 83-4, 83-5. The plurality of first light deflection units 83-1, 83-2, 83-3, 83-4, 83-5 deflect their respective lights while combining them.

[0191] The drive unit 13 includes a reflecting unit 14 and scans the light deflected by the first optical deflection unit 83 toward the second optical deflection unit 85 in a two-dimensional direction. At this time, the drive unit 13 scans the light deflected by the first optical deflection unit 83 by, for example, raster scanning and forms an image. The drive unit 13 can scan the light deflected by the first optical deflection unit 83 by spiral scanning.

[0192] The second light deflection unit 85 is, for example, a holographic optical element, which deflects the light L1 scanned by the drive unit 13 toward the user's eyeball 87. At least a portion of the light L2 deflected by the second light deflection unit 85 is incident on the user's eyeball 87 as display image light. The second light deflection unit 85 may also comprise multiple light deflection members. For example, multiple types of light deflection members that reflect specific light from the light emitted from the light source 82 may be used, so that the reflective surface differs for each type of light emitted from the light source 82. A specific example is a configuration in which light deflection members that reflect light emitted from laser light sources 82r, 82g, and 82b are stacked in order from closest to the eyeball 87, and a light deflection member that reflects light emitted from an infrared laser light source 82ir is stacked.

[0193] The light-receiving unit 86 receives light L3 reflected by the user's eyeball 87 from the light L2 deflected by the second light deflection unit 85, and outputs a detection signal SD corresponding to the received light. The light-receiving unit 86 is, for example, an image sensor capable of detecting infrared light. Multiple light-receiving units 86 may be provided at positions capable of receiving light L3 reflected by the user's eyeball 87. The light intensity of the light received by the light-receiving unit 86 changes depending on the position of the eyeball (pupil, cornea, etc.), i.e., the direction of line of sight. Therefore, the pupil or corneal position detection device 80 in this embodiment detects or estimates the pupil or corneal position based on the intensity of the light received by the light-receiving unit 86. The light-receiving unit 86 may also be configured to image the eyeball 87 illuminated by the light L2 deflected by the second light deflection unit 85. In this case, the pupil or corneal position detection device 80 detects or estimates the tilt position of the eyeball based on the position of the pupil or cornea included in the captured image (detection signal SD) and the position where the light L2 deflected by the second light deflection unit 85 is reflected in the eyeball 87.

[0194] As described above, the pupil or corneal position detection device 80 according to this embodiment can detect the position of the pupil or cornea while forming an image with the drive device 13. Furthermore, since the drive device 13 is configured to scan light more efficiently, it can achieve image formation and detection of the pupil or corneal position with lower power consumption. Moreover, the drive device 13 can achieve the above effects without changing the area required for mounting on the pupil or corneal position detection device 80 compared to the configuration of the conventional technology. As a result, the pupil or corneal position detection device 80 can be configured without becoming larger.

[0195] Furthermore, the pupil or corneal position detection device 80 can also be mounted on a head-mounted display as, for example, an eye-tracking device to detect or track the user's gaze direction. In this case, for example, by reducing the resolution of the image displayed in other areas compared to the image displayed in the area near the user's gaze direction (foveal rendering), image processing can be sped up compared to displaying a high-resolution image across the entire area.

[0196] Figure 29 is a schematic diagram showing an example of a pupil or corneal position detection device 80. As shown in Figure 29, the pupil or corneal position detection device 80 comprises a light source 82, first light deflection units 83-1 to 83-4, lens 92, lens 93, movable unit 101, movable unit 101B, second light deflection unit 85, light receiving unit 86, and drive control unit 11. The movable unit 101 may be, for example, a scanning mirror, and the movable unit 101B may be a deflection mirror.

[0197] Lens 92 is an optical system that converts light emitted from the light source 82 into substantially parallel light. Lens 93 is an optical system that shapes the light converted into substantially parallel light by lens 92 into a desired laser beam state. In this embodiment, a configuration including lens 92 and lens 93 is shown, but lenses 92 and 93 are not necessarily required.

[0198] Light formed by lenses 92 and 93 enters the movable part 101. The movable part 101 scans the incident light to form image light. The formed image light enters the movable part 101B, which is a deflection mirror, and is reflected in the direction toward the second light deflection part 85. The movable part 101B corresponds to the first light deflection part 83-5 described in Figure 29, but it is preferable that it is configured to scan light and is equipped with a drive device 13. By configuring the movable part 101B, which is a deflection mirror, to be light-scanning, an image can be projected over a wider area.

[0199] In the above description, a configuration is given in which the movable part 101B, which is a deflection mirror, is positioned between the movable part 101, which is a scanning mirror, and the second light deflection part 85. However, the pupil or corneal position detection device 80 is not limited to this configuration. In the pupil or corneal position detection device 80, the movable part 101, which is a scanning mirror, may be positioned between the movable part 101B, which is a deflection mirror, and the second light deflection part 85. The light reflected by the movable part 101B may be scanned in two axial directions by the movable part 101 and incident on the second light deflection part 85.

[0200] The drive control unit 11 detects the position of the user's pupil or cornea based on the detection signal SD output by the light receiving unit 86 and acquires information indicating the direction of gaze. The drive control unit 11 also controls the emission and light intensity of the light source 82 by providing a formation drive signal SL1 to the light source 82 to form an image to be projected onto the retina 65, and drives the movable unit 101 by providing a scanning drive signal SS to the movable unit 101. Furthermore, if the movable unit 101B is configured to be optically scannable, the drive control unit 11 drives the movable unit 101B by providing a deflection drive signal ST to the movable unit 101B in order to control the projection position of the image according to the acquired gaze information.

[0201] The eyeball tilt position detection device 80, by including a drive unit 13, can accurately control the drive units 110a and 110b using a drive signal containing multiple frequency components, thereby enabling high-precision optical scanning.

[0202] Although examples of embodiments of this disclosure have been described above, this disclosure is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of this disclosure as described in the claims.

[0203] In the embodiments described above, a configuration in which a reflective surface is provided on the movable part is illustrated, but the invention is not limited to this. The movable part may also be equipped with other optical elements such as a diffraction grating, a photodiode, a heater (for example, a heater using SiN), or a light source (for example, a surface-emitting laser), or it may be equipped with both a reflective surface and other optical elements.

[0204] [Processing circuit] Each function of the embodiments described above can be realized by one or more processing circuits. Here, "processing circuit" as used herein includes processors programmed to execute each function by software, such as processors implemented by electronic circuits, as well as devices such as ASICs (Application Specific Integrated Circuits), DSPs (digital signal processors), FPGAs, and conventional circuit modules designed to execute each function described above. A "processor" comprises various computing devices such as a CPU and a GPU (Graphics Processing Unit). The processor reads various programs into memory and executes them.

[0205] The aspects of this disclosure may include, for example, the following:

[0206] <1> The drive device comprises a movable part, a drive unit for driving the movable part, a drive control unit for controlling the drive unit with a drive signal containing multiple frequency components, and a detection unit for detecting the displacement of the movable part, wherein the drive control unit corrects the frequency components included in the drive signal based on the combined frequency component of the multiple frequency components decomposed from the detection signal by the detection unit. <2> The drive control unit controls the drive unit using the drive signals of a plurality of drive signals whose combined frequency components have different amplitudes, and corrects the frequency components included in the drive signals based on the combined frequency components decomposed from the detection signal, which correspond to each of the plurality of drive signals. <1> This is the drive device described in [reference]. <3> The drive control unit corrects the frequency components included in the drive signal based on the input amplitude of the composite frequency component in the drive signal when the detection amplitude of the composite frequency component decomposed from the detection signal is minimized among the plurality of drive signals. <2> This is the drive device described in [reference]. <4> The movable part includes a reflective part that reflects light, and the drive control unit controls the drive part with each of the drive signals of a plurality of drive signals whose input amplitudes of the combined frequency components are different from each other, without reflecting light with the reflective part, and performs a first drive control that corrects the frequency components included in the drive signal based on the combined frequency components decomposed from the detection signal corresponding to each of the plurality of drive signals, and a second drive control that reflects light with the reflective part and controls the drive part with the drive signal, <2> or the above <3> This is the drive device described in [reference]. <5> The drive control unit searches for the input amplitude that minimizes the detected amplitude while changing the input amplitude multiple times within a predetermined search range, and when n is a natural number, the absolute value of the change in the input amplitude when the drive control unit changes the input amplitude for the (i+1)th time is smaller than the absolute value of the change in the input amplitude when it changes the input amplitude for the ith time, and the absolute value of the change in the input amplitude when the drive control unit changes the input amplitude for the (i+2)th time is smaller than the absolute value of the change in the input amplitude when it changes the input amplitude for the (i+1)th time, <3> This is the drive device described in [reference]. <6> The drive control unit searches for the input amplitude that minimizes the detected amplitude while changing the input amplitude multiple times within a predetermined search range, and the range of change of the input amplitude is constant regardless of the number of times the input amplitude is changed. <3> This is the drive device described in [reference]. <7> The drive control unit determines the input amplitude at which the detection amplitude is minimized by using either interpolation or extrapolation in the change interval where the detection amplitude is minimized, among a plurality of change intervals in which the detection amplitude changes in accordance with the change range of the input amplitude. <5> or the above <6> This is the drive device described in [reference]. <8> The drive control unit uses an approximate formula representing the relationship between the input amplitude and the detection amplitude to determine the input amplitude at which the detection amplitude is minimized. <5> or the above <6> This is the drive device described in [reference]. <9> The aforementioned <1> from the above <6> A projection device comprising an optical scanning system including a drive device as described in any one of the above. <10> The aforementioned <1> from the above <6> A head-mounted display equipped with a drive device as described in any one of the above. <11> The aforementioned <1> from the above <6> A head-up display equipped with a drive device as described in any one of the above. <12> The aforementioned <1> from the above <6> This is a laser headlamp equipped with a drive device as described in any one of the following. <13> The aforementioned <1> from the above <6> This is an object recognition device equipped with a drive mechanism as described in any one of the following. <14> The aforementioned <11> The head-up display described above, <12> The laser headlamp and the <13> It is a mobile body equipped with at least one of the object recognition devices described above. <15> A driving method for a drive device comprising a movable part, a drive unit for driving the movable part, and a detection unit for detecting the displacement of the movable part, wherein the drive unit is controlled by a drive signal containing a plurality of frequency components, and the frequency components included in the drive signal are corrected based on the combined frequency component of the plurality of frequency components decomposed from the detection signal by the detection unit. <16> A program for causing a computer to execute a driving method for a drive device comprising a movable part, a drive unit for driving the movable part, and a detection unit for detecting the displacement of the movable part, wherein the program controls the drive unit with a drive signal containing multiple frequency components, and corrects the frequency components included in the drive signal based on the combined frequency component of the multiple frequency components decomposed from the detection signal by the detection unit. [Explanation of Symbols]

[0207] 10 Optical scanning system 11 Drive control unit 13 Drive unit 14 Reflector 20 CPU 21 RAM 22 ROM 23 FPGA 24 External I / F 26 Drive unit driver 30 Control Unit 31 Input section 32 Drive signal output section 50 Laser Headlamps 60 Head-mounted displays 101 Moving parts 102 Movable part base 103 Movable thick wall part 110a, 110b, 110c, 110d Drive unit 111a, 111b, 111c, 111d Torsion bar 112a, 112b, 112c, 112d First piezoelectric drive unit 113a, 113b, 113c, 113d Drive beams 120 First Support Slot 130a, 130b First support frame drive unit 131a, 131b, 131c, 131d, 131e, 131f Second piezoelectric drive unit 132a, 132b, 132c, 132d, 132e, 132f Second piezoelectric drive unit 140 Second Support Slot 150 Electrode connection section 160a, 160b, 160c, 160d detection unit 161 Silicon support layer 162 Silicon Oxide Layer 163 Silicon Active Layer 201 Lower electrode 202 Piezoelectric part 203 Upper electrode 301 Lower electrode 302 Piezoelectric part 303 Upper electrode 311 1st calculation section 312 2nd calculation section 400 Automobiles (mobile vehicles) 500 Head-up display device (projection device) 600 Optical writing device 610 Image forming apparatus 700 Laser radar system (object recognition system) B System Bathroom La1 1st approximation straight line La2 2nd approximate straight line O1 Image Center O14 Center of field of view [Prior art documents] [Patent Documents]

[0208] [Patent Document 1] Japanese Patent Publication No. 2023-001729

Claims

1. Movable parts and A drive unit for driving the aforementioned movable part, A drive control unit that controls the drive unit with a drive signal containing multiple frequency components, The system includes a detection unit for detecting the displacement of the movable part, The drive control unit, A drive device that corrects the frequency components included in the drive signal based on the combined frequency component of the plurality of frequency components decomposed from the detection signal by the detection unit.

2. The drive control unit controls the drive unit using the drive signals of a plurality of drive signals whose combined frequency components have different amplitudes, The drive device according to claim 1, which corrects the frequency components included in the drive signal based on the composite frequency components decomposed from the detection signal, corresponding to each of the plurality of drive signals.

3. The drive control unit corrects the frequency components included in the drive signal based on the input amplitude of the composite frequency component in the drive signal when the detection amplitude of the composite frequency component decomposed from the detection signal is minimized among the plurality of drive signals, according to claim 2.

4. The aforementioned movable part is equipped with a reflective part that reflects light, The drive control unit, Without reflecting light with the reflective portion, the drive unit is controlled by the drive signals of a plurality of drive signals, each having a different input amplitude for the combined frequency component, and a first drive control is performed to correct the frequency component included in the drive signal based on the combined frequency component decomposed from the detection signal, which corresponds to each of the plurality of drive signals. The drive device according to claim 2, which performs a second drive control that reflects light with the reflective part and controls the drive part with the drive signal.

5. The drive control unit searches for the input amplitude that minimizes the detected amplitude while changing the input amplitude multiple times within a predetermined search range. Let n be a natural number. The absolute value of the change in the input amplitude when the drive control unit changes the input amplitude for the (i+1)th time is smaller than the absolute value of the change in the input amplitude when it changes the input amplitude for the ith time. The drive device according to claim 3, wherein the absolute value of the change in the input amplitude when the drive control unit changes the input amplitude for the (i+2)th time is smaller than the absolute value of the change in the input amplitude when the input amplitude is changed for the (i+1)th time.

6. The drive control unit searches for the input amplitude that minimizes the detected amplitude while changing the input amplitude multiple times within a predetermined search range. The drive device according to claim 3, wherein the range of change of the input amplitude is constant regardless of the number of times the input amplitude is changed.

7. The drive control unit determines the input amplitude at which the detection amplitude is minimized in the change interval where the detection amplitude is minimized, using either interpolation or extrapolation, among a plurality of change intervals in which the detection amplitude changes in accordance with the change range of the input amplitude, according to claim 5 or claim 6.

8. The drive control unit determines the input amplitude when the detection amplitude is minimized using an approximate formula representing the relationship between the input amplitude and the detection amplitude, according to claim 5 or claim 6.

9. A projection apparatus comprising an optical scanning system including a drive device according to any one of claims 1 to 6.

10. A head-mounted display comprising a drive device according to any one of claims 1 to 6.

11. A head-up display comprising the drive device described in claim 1.

12. A laser headlamp comprising the drive device described in claim 1.

13. An object recognition device comprising the drive device described in claim 1.

14. A mobile body comprising at least one of the head-up display described in claim 11, the laser headlamp described in claim 12, and the object recognition device described in claim 13.

15. Movable parts and A drive unit for driving the aforementioned movable part, A driving method in a drive device comprising a detection unit for detecting the displacement of the movable part, A driving method comprising controlling the drive unit with a drive signal containing multiple frequency components, and correcting the frequency components included in the drive signal based on the combined frequency component of the multiple frequency components decomposed from the detection signal by the detection unit.

16. Movable parts and A drive unit for driving the aforementioned movable part, A program that causes a computer to execute a driving method for a drive device equipped with a detection unit for detecting the displacement of the movable part, A program that controls the drive unit with a drive signal containing multiple frequency components, and corrects the frequency components included in the drive signal based on the combined frequency component of the multiple frequency components decomposed from the detection signal by the detection unit.

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