JP2024068414A - Movable device, optical scanning system, head-up display, laser headlamp, head-mounted display, object recognition device and moving body. - Google Patents

Abstract

【assignment】
To provide a movable device that can be made compact while increasing drive sensitivity.
SOLUTION
The present invention is a movable device comprising a movable part, a driving part which drives the movable part, and a connecting part which connects the movable part and the driving part, wherein the connecting part has a gap in an area which overlaps with at least one of the movable part and the driving part in a planar view, and the length of the connecting part between the connection position with the movable part and the connection position with the driving part, excluding the connection area between the movable part and the driving part in a planar view, is longer than the distance between the driving part and the movable part in a planar view.
[Selected Figure] Figure 1E

Description

The present invention relates to a movable device, an optical scanning system, a head-up display, a laser headlamp, a head-mounted display, an object recognition device, and a moving body.

In Patent Document 1, a cavity that opens onto the silicon oxide layer side of an SOI wafer is formed in a region where an outer piezoelectric actuator is to be formed by etching from the silicon oxide layer side, and the exposed surface of the cavity is covered with a silicon oxide layer. Next, the silicon oxide layer of the SOI wafer is bonded to a support layer of the SOI wafer to produce an SOI wafer with an enclosed cavity. Next, a recess is formed on the back side of the SOI wafer, and then anisotropic dry etching is performed from the back side in the depth direction of the recess to remove the silicon oxide layer.

JP 2020-204695 A

To provide a movable device that can be made compact while increasing drive sensitivity.

The present invention is a movable device that includes a movable part, a drive part that drives the movable part, and a connecting part that connects the movable part and the drive part, and is characterized in that there is an area where the drive part and the connecting part overlap, and the overlapping area has a space between the drive part and the connecting part that is open to the movable part.

It is possible to provide a movable device that can be made compact while still improving drive sensitivity.

FIG. 1 is a plan view showing an example of a configuration of an embodiment of the present invention. FIG. 2 is a rear view showing an example of the configuration of this embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 4 is a schematic representation of the drive of a second drive structure of the movable device; (a) An example of the waveform of a driving voltage A applied to a piezoelectric element group A of a movable device; (b) an example of the waveform B of a driving voltage applied to a piezoelectric element group B; (c) a diagram showing the waveforms of driving voltage A and driving voltage B superimposed on each other. FIG. 1 is a plan view showing an example of a configuration of an embodiment of the present invention. FIG. 2 is a rear view showing an example of the configuration of this embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 1 is a plan view showing an example of a configuration of an embodiment of the present invention. FIG. 2 is a rear view showing an example of the configuration of this embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 1 is a plan view showing an example of a configuration of an embodiment of the present invention. FIG. 2 is a rear view showing an example of the configuration of this embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 1 is a plan view showing an example of a configuration of an embodiment of the present invention. FIG. 2 is a rear view showing an example of the configuration of this embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 1 is a plan view showing an example of a configuration of an embodiment of the present invention. FIG. 2 is a rear view showing an example of the configuration of this embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. FIG. 2 is a cross-sectional view of a plan view showing an example of a configuration of the present embodiment. 1 is a schematic diagram of an example optical scanning system. FIG. 2 is a diagram illustrating a hardware configuration of an example of an optical scanning system. FIG. 2 is a functional block diagram of an example of a control device. 13 is a flowchart of an example of a process related to the optical scanning system. 1 is a schematic diagram of an example of an automobile equipped with a head-up display device. 1 is a schematic diagram of an example of a head-up display device. 1 is a schematic diagram of an example of an image forming apparatus equipped with an optical writing device. FIG. 1 is a schematic diagram of an example of an optical writing device. FIG. 1 is a schematic diagram of an example of an automobile equipped with a lidar device. FIG. 1 is a schematic diagram of an example of a lidar device. FIG. 1 is a schematic diagram illustrating an example of the configuration of a laser headlamp. FIG. 1 is a schematic perspective view showing an example of the configuration of a head mounted display. FIG. 2 is a diagram illustrating an example of a portion of the configuration of a head mounted display.

Below, a description of the embodiment of the invention will be given with reference to the drawings. Note that in the description of the drawings, the same elements are given the same reference numerals, and duplicate descriptions will be omitted.

[First embodiment]
<Configuration of movable device>
The first embodiment is shown in Fig. 1. Fig. 1A is a front view, Fig. 1B is a rear view, and Figs. 1C to 1E are cross-sectional views.

As shown in FIG. 1, the movable device 13 has a mirror section 101 that reflects incident light, first drive structure sections 110a and 110b that are connected to the mirror section and drive the mirror section around a first axis parallel to the Y axis, a first support section 120 that supports the mirror section and the first drive structure section, second drive structure sections 130a and 130b that are connected to the first support section and drive the mirror section and the first support section around a second axis parallel to the Y axis, a second support section 140 that supports the second drive structure section, and an electrode connection section 150 that is electrically connected to the first drive structure section, the second drive structure section, and the control device.

The movable device 13 is formed, for example, by bonding two SOI substrates, a first SOI (Silicon On Insulator) substrate 361 and a second SOI substrate 362, with a silicon oxide layer 363 sandwiched between them. The first SOI substrate is formed of a silicon support layer 361a, a silicon oxide layer 361b, and a silicon active layer 361c, and the second SOI substrate is formed of a silicon support layer 362a, a silicon oxide layer 362b, and a silicon active layer 362c. Each SOI substrate is shaped by etching or the like, and the reflective surface 14, the first driving units 112a, 112b, the second driving units 131a to 131d, 132a to 132d, the electrode connection unit 150, and the like are formed on the shaped substrate, so that each component is integrally formed. The formation of each of the above components may be performed after the SOI substrate is shaped, or may be performed during the shaping of the SOI substrate.

As mentioned above, the drive units include first drive units 112a, 112b arranged in the first drive structure unit 110, and second drive units 131a-131d, 132a-132d arranged in the second drive structure unit 130. Since the main structure in this embodiment is the first drive unit, for the sake of simplicity, the first drive unit may be referred to as the drive unit.

An SOI substrate is a substrate in which a silicon oxide layer is provided on a first silicon layer made of single crystal silicon (Si), and a second silicon layer made of single crystal silicon is provided on the silicon oxide layer. Hereinafter, the first silicon layer is referred to as silicon support layers 361a, 362a, and the second silicon layer is referred to as silicon active layers 361c, 362c.

Since the silicon active layers 361c and 362c are thinner in the Z-axis direction than in the X-axis direction or the Y-axis direction, a member made up of only the silicon active layer functions as an elastic part.

The SOI substrate does not necessarily have to be planar, and may have curvature, etc. Also, the material used to form the movable device 13 is not limited to the SOI substrate, as long as it can be integrally molded by etching or the like and can be made partially elastic.

Next, the main scanning structure for rotating about the first axis will be described in detail.
The mirror section 101 is composed of, for example, a circular mirror section base 102 made of a silicon active layer 361c, and a reflecting surface 14 formed on the +Z side surface of the mirror section base. The mirror section base 102 is composed of, for example, a silicon active layer 361c. The reflecting surface 14 is composed of a metal thin film containing, for example, aluminum, gold, silver, or the like.
1B, the mirror section 101 may have a rib 103 for reinforcing the mirror section formed on the −Z side surface of the mirror section base 102. The rib is made of, for example, a silicon support layer 361a and a silicon oxide layer 361b, and can suppress distortion of the reflecting surface 14 that occurs when the mirror oscillates.

The first drive structure 110a, 110b is composed of the drive units 112a, 112b made of the silicon active layer 361c and the torsion springs 111a, 111b. The drive units 112a, 112b are made of a silicon active layer having a first piezoelectric element unit, and the back surfaces of the drive units 112a, 112b are formed with the drive unit ribs 114a, 114b and the drive unit connection units 113a, 113b described later. One end of the drive units 112a, 112b is connected to the torsion bar springs 111a, 111b described later, and the other end is connected to the inner periphery of the first support unit 120.

The first piezoelectric element portion is configured by forming a lower electrode 201, a piezoelectric portion 202, and an upper electrode 203 in this order on the +Z side surface of the silicon active layer 361c, which is the elastic portion, as shown in FIG. 1E. The upper electrode 203 and the lower electrode 201 are configured, for example, from gold (Au) or platinum (Pt). The piezoelectric portion 202 is configured, for example, from PZT (lead zirconate titanate), which is a piezoelectric material.

As shown in FIG. 1B, the torsion bar springs 111a and 111b are configured from the silicon active layer 362c of the second SOI substrate 362 with the first axis direction as the longitudinal direction. The mirror section 14 is an example of a movable section, and the actuators 112a and 112b are an example of an actuator. The torsion bar springs 111a and 111b are an example of a part that configures a connecting section.

Torsion bar springs 111a and 111b each have one end connected to mirror rib 103 via mirror connector 104, and the other end connected to drivers 112a and 112b via driver connectors 113a and 113b, rotatably supporting mirror 101. The mirror resonance frequency is designed based on the length, width, and thickness of torsion bar spring 111a.

When the torsion bar spring 111a shown in FIG. 1B, which is a plan view, is viewed in cross section at the point where it is connected to the mirror base 102 via the mirror connection part 104 and the mirror rib 103, as shown in FIG. 1E, the mirror base 102 is connected to the connection part 111a via a connection region 591 (connection between the movable part and the connection part) on the stack. The connection region 591 is composed of the silicon support layer 361a of the first SOI substrate and the silicon active layer 362c of the second SOI substrate. The connection region 591 is an example of a part that constitutes the connection part 111a.

The mirror connection portion 104, which is shown in a plan view as a part of the connection region, is an example of a part that constitutes the link portion 111a. In this embodiment, the mirror connection portion 104 and the mirror portion rib 103 are formed in different layers, but they may be formed integrally. When the mirror connection portion 104 and the mirror portion rib 103 are formed integrally, it is preferable that the rigidity is high in order to reinforce the mirror portion 101. However, for example, the rigidity of the mirror connection portion 104 may be reduced to the same level as the torsion bar springs 111a and 111b, thereby increasing the drive sensitivity of the movable device.

The torsion bar spring 111a shown in FIG. 1B, which is a plan view, is connected to the driving unit 112a via the driving unit connection part 113a. As shown in FIG. 1E, which is a cross-sectional view, the driving unit 112a is connected to the torsion bar spring 111a via a connection region 590 (connection between the driving unit and the connecting part) on the stack. The connection region 590 is composed of the silicon support layer 361a of the first SOI substrate and the silicon active layer 362c of the second SOI substrate. The connection region 590 is an example of a part that constitutes the connecting part 111a.

The drive unit connection parts 113a and 113b are an example of a part that constitutes the coupling part. In this embodiment, the drive unit connection parts 113a and 113b and the drive unit ribs 114a and 114b are formed in different layers, but they may be formed integrally as in the fourth embodiment described later. When the drive unit connection parts 113a and 113b are formed integrally with the mirror unit rib 103 or the drive unit ribs 114a and 114b, it is preferable that the rigidity is high in order to reinforce the drive units 112a and 112b. However, for example, the rigidity of the drive unit connection parts 113a and 113b may be reduced to the same level as the torsion bar springs 111a and 111b, thereby increasing the drive sensitivity of the movable device.

The driving units 112a and 112b are composed of a first piezoelectric element unit and a silicon active layer 361c that supports it. The first piezoelectric element unit is designed to exert a driving force, and the silicon active layer 361c unit is conveniently designed in a shape suitable for bonding to the connecting unit 111a and for bonding to the support unit 120. The silicon active layer 361c also plays a role in supporting the driving force provided by the support unit 120.

The shapes of the first piezoelectric element portion and the silicon active layer 361c are processed using separate photolithography processes, so any shape can be formed without significant restrictions on the shape of each portion.

As shown in FIG. 1B, the torsion bar springs 111a and 111b are configured from the silicon active layer 362c of the second SOI substrate 362 with the first axis direction as the longitudinal direction. The mirror portion 14 is an example of a movable portion, and the driving portion 112a is an example of a driving portion. The torsion bar spring 111a is an example of a connecting portion.

One end of each of the torsion bar springs 111a and 111b is connected to the mirror section rib 103 via the mirror connection section 104. The other ends of the torsion bar springs 111a and 111b are connected to the drive sections 112a and 112b via the drive section connection sections 113a and 113b. They support the mirror section 101 so that it can rotate. The mirror resonance frequency is designed based on the length, width, and thickness of the torsion bar spring 111a.

As shown in Figure 1B, the torsion bar spring offsets (dS) its torsional axis from the center of the mirror, converting the amplitude of the Z direction at the tip of the driver into a rotational force (moment) to rotate the mirror. Because the tip of the driver is a free end, a large amplitude can be obtained without interfering with the piezoelectric driving force.

Furthermore, by setting the bending mode resonance of the drive unit close to the mirror resonance (the torsion mode resonance of the torsion bar spring), the rotation angle of the mirror can be greatly expanded, enabling large amplitude operation with a low applied voltage. The stiffness is designed by the shape and width of the drive unit ribs 114a, 114b, and the resonance frequency of the bending mode of the drive unit is set to the desired value.

Returning to FIG. 1A, the first support unit 120 is, for example, a support having a substantially rectangular shape and made up of a silicon support layer 361a, a silicon oxide layer 361b, and a silicon active layer 361c, and is formed to surround the mirror unit 101 and the first drive units 112a and 112b.

As can be seen from the E-E' cross section in Figure 1E, the mirror base 102 and the torsion bar spring 111a overlap in the Z direction. Also, the torsion bar spring 111a and the drive unit 112a overlap in the Z direction.

Note that a planar view means viewing an object from the normal direction of the top surface of the mirror section 14. For reference, FIG. 1A shows an X-axis, a Y-axis, and a Z-axis that are mutually orthogonal. The X-axis direction and the Y-axis direction are directions that are mutually orthogonal in a plane that is parallel to the top surface of the mirror section 14. The Z-axis direction is a direction that is orthogonal to the X-axis direction and the Y-axis direction. In other words, the Z-axis direction is the normal direction of the top surface of the mirror section 14. Here, the mirror section 14 in a planar view refers to the mirror section 14 shown in the XY plane in FIG. 1A. Note that the X-axis, Y-axis, and Z-axis corresponding to FIG. 1A may also be shown in other figures.

A first silicon support layer 361a is disposed between the mirror section 14 and the torsion bar spring 111a, and a space 580 is formed. The space 580 is open to the drive section 112a side.

A first silicon support layer 361a is also disposed between the drive unit 112a and the torsion bar spring 111a, and a space 580 is formed with a gap equal to the thickness of the first silicon support layer 361a. The space 580 is open to the mirror 14 side.

As a result, the length of the torsion bar spring 111a, which is the spring constant of the torsion bar spring 111a, extends to the area including the space where the mirror section 14 and the drive section 112a are open. In effect, a torsion bar spring with the same spring constant can be stacked below the mirror section without shortening the torsion bar spring. This overlapping area essentially allows the first support section 120 to be formed compactly.

The torsion bar spring 111a and the driving unit 112a are connected by the first silicon support layer 361a, and are bonded so as to be stacked in the thickness direction. Here, the thickness direction refers to the Z-axis direction shown in FIG. 1E. In other words, the thickness direction is the same as the stacking direction of the silicon support layer 361a, silicon oxide layer 361b, and silicon active layer 361c in the first support unit 120. This bonded portion is referred to as the bonding region 590. Similarly, the mirror unit 14 and the driving unit 112a are connected by the first silicon support layer 361a, and are bonded so as to be stacked in the thickness direction. This bonded portion is referred to as the bonding region 591.

By arranging this joint area in the thickness direction, it is possible to narrow the joint area in the planar direction compared to the conventional method of joining in the planar direction. This makes it possible to design the first support part 120 compactly without changing the actual length of the torsion bar spring by the narrower area. As a movable device, it is possible to reduce the size while maintaining the same spring constant and the amplitude of the deflection.

Figure 1E shows the distance relationship between each of the main components. The distance 501 between the movable part and the drive part and the connecting part is L1. L1 indicates the distance in the Z-axis direction, and by indicating that L1 is a finite value, it is intended that there is a space here. This space allows the torsion bar spring 111a to move.

Next, the length of the space 502 formed between the movable part and the drive part and the connecting part is defined as L2. At this time, this is the length of the torsion bar spring between the drive part and the movable part, excluding the connection area (connection between the drive part and the connecting part) 590 and the connection area (connection between the movable part and the connecting part) 591. This connection area is the surface of the torsion bar spring that connects to the drive part or the movable part and the part that is continuous with this surface in the Z-axis direction, and is a columnar area with the connecting surface as its bottom surface.

Finally, the distance 503 between the movable part and the driving part is L3. Since L3 is finite, the movable part and the driving part do not come into direct contact with each other.

By bonding two SOI substrates as in this embodiment, a three-dimensional structure can be created. In other words, by forming L1 from the silicon support layer 361a, it is possible to achieve L2 that is much larger than L3. L2 is an important factor that determines the spring constant, and by making L3 as small as possible without restricting this value, it is possible to achieve a large moving part and a small moving device.

In the previous explanation, the torsion bar spring is referred to as 111a and the drive unit as 112a, but as can be seen from the figure, this embodiment has symmetry, and the above-described arrangement is similar for the torsion bar spring 111b and the drive unit 112b. In the following, only 111a and 112a may be described as representative, but this includes 111b and 112b and is not limited to 111a and 112a.

In this way, the mirror section 14 and the driving section 112a are formed from the silicon active layer 361c of the first SOI substrate, and the torsion bar spring is formed from the silicon active layer 362c of the second SOI substrate, so that they can be stacked three-dimensionally with a gap of the thickness of the first silicon support layer 361a to form a compact structure. This also makes it possible to reduce the moment of inertia of the main scanning structure.

Next, the details of the sub-scanning structure for rotating around the second axis will be described. The second drive structure 130a, 130b is composed of a plurality of second drive structure parts 131a-131d, 132a-132d, for example, connected in a folded manner, and one end of the second drive structure parts 130a, 130b is connected to the outer periphery of the first support part 120, and the other end is connected to the inner periphery of the second support part 140. At this time, the connection part between the second drive structure part 130a and the first support part 120 and the connection part between the second drive structure part 130b and the first support part 120, as well as the connection part between the second drive structure part 130a and the second support part 140 and the connection part between the second drive structure part 130b and the second support part 140 are point symmetrical with respect to the center of the reflecting surface 14.

As shown in FIG. 1C, the second drive structure 130a, 130b is configured by forming a lower electrode 201, a piezoelectric portion 202, and an upper electrode 203 in this order on the +Z side surface of the silicon active layer 361c, which is the elastic portion. The upper electrode 203 and the lower electrode 201 are made of, for example, gold (Au) or platinum (Pt). The piezoelectric portion 202 is made of, for example, PZT (lead zirconate titanate), which is a piezoelectric material.

Returning to FIG. 1A, the second support section 140 is a rectangular support body formed by bonding two SOI substrates, a first SOI substrate 361 and a second SOI substrate 362, with a silicon oxide layer 363 sandwiched between them, and is formed to surround the mirror section 101, the first drive structure sections 110a and 110b, the first support section 120, and the second drive structure sections 130a and 130b.

The electrode connection portion 150 is formed, for example, on the +Z side surface of the second support portion 140, and is electrically connected to each upper electrode 203 and each lower electrode 201 of the first drive portion 112a, 112b, the second piezoelectric drive portion 131a to 131d, 132a to 132d via electrode wiring such as aluminum (Al). Note that the electrode wiring is not shown in FIG. 1A. The upper electrode 203 or the lower electrode 201 may each be directly connected to the electrode connection portion, or may be indirectly connected by connecting the electrodes to each other, etc.

In this embodiment, the piezoelectric portion 202 is formed only on one surface (the surface on the +Z side) of the silicon active layer 361c, which is the elastic portion, as an example. However, the piezoelectric portion 202 may be provided on another surface (for example, the surface on the -Z side) of the elastic portion, or may be provided on both one surface and the other surface of the elastic portion.

In addition, as long as the mirror unit can be driven around the first axis or the second axis, the shape of each component is not limited to the shape of the embodiment. For example, the torsion bar springs 111a, 111b and the first drive units 112a, 112b may have a shape with a curvature.

Furthermore, an insulating layer made of a silicon oxide film may be formed on at least one of the +Z side surface of the upper electrode 203 of the first driving structure 110a, 110b, the +Z side surface of the first support part, the +Z side surface of the upper electrode 203 of the second driving structure 130a, 130b, and the +Z side surface of the second support part. In this case, an electrode wiring is provided on the insulating layer, and the insulating layer is partially removed or not formed as an opening only at the connection spot where the upper electrode 203 or the lower electrode 201 is connected to the electrode wiring, thereby increasing the design freedom of the first driving structure 110a, 110b, the second driving structure 130a, 130b, and the electrode wiring, and further suppressing short circuits due to contact between the electrodes. In addition, the silicon oxide film also functions as an anti-reflection material.

[Details of control of the control device]
Next, details of the control of the control device that drives the first drive structure and the second drive structure of the movable device will be described.

When a positive or negative voltage is applied in the polarization direction, the piezoelectric section 202 of the first driving structure 110a, 110b and the second driving structure 130a, 130b undergoes deformation (e.g., expansion and contraction) proportional to the potential of the applied voltage, thereby exerting the so-called inverse piezoelectric effect. The first driving structure 110a, 110b and the second driving structure 130a, 130b utilize the inverse piezoelectric effect to move the mirror section 101.

In this case, the angle formed by the XY plane and the reflecting surface 14 when the reflecting surface 14 of the mirror section 101 is tilted in the +Z direction or the -Z direction with respect to the XY plane is called the deflection angle. In this case, the +Z direction is the positive deflection angle, and the -Z direction is the negative deflection angle.

First, the control of the control device that drives the first drive structure will be described.
In the first drive structure 110a, 110b, when a drive voltage is applied in parallel to the piezoelectric portion 202 of the first drive portion 112a, 112b via the upper electrode 203 and the lower electrode 201, each piezoelectric portion 202 is deformed. The action of the deformation of the piezoelectric portion 202 causes the first drive portion 112a, 112b to bend and deform. As a result, a drive force about the first axis acts on the mirror portion 101 via the twist of the two torsion bar springs 111a, 111b, and the mirror portion 101 moves about the first axis. The drive voltage applied to the first drive structure 110a, 110b is controlled by the control device 11.

Therefore, the control device 11 can apply a predetermined sinusoidal waveform drive voltage in parallel to the first drive units 112a and 112b of the first drive structure units 110a and 110b, thereby moving the mirror unit 101 around the first axis at a period of the predetermined sinusoidal waveform drive voltage.

In particular, for example, when the frequency of the sinusoidal voltage is set to approximately 20 kHz, which is similar to the resonant frequency of the torsion bar springs 111a and 111b, the mirror portion 101 can be made to resonate and vibrate at approximately 20 kHz by utilizing the mechanical resonance caused by the twisting of the torsion bar springs 111a and 111b.

Next, the control of the control device that drives the second drive structure will be described with reference to Figs. 1 to 3. Fig. 2 is a schematic diagram showing the drive of the second drive structure 130b of the movable device. The mirror section 101 and the like are shown in dotted lines. Note that the right direction on the paper is the +X direction, the upward direction on the paper is the +Y direction, and the front of the paper is the +Z direction.

As shown in FIG. 2(i), when no drive voltage is applied to the second drive structure 130b, the deflection angle caused by the second drive structure is zero.

Of the multiple second drive units 131a to 131d that the second drive structure unit 130a has, the even-numbered second drive units, counting from the second drive unit (131a) that is closest to the mirror unit, i.e., the second drive units 131b and 131d, are defined as piezoelectric element unit group A. Furthermore, of the multiple second drive units 132a to 132d that the second drive structure unit 130b has, the odd-numbered second drive units, counting from the second drive unit (132a) that is closest to the mirror unit, i.e., the second drive units 132a and 132c, are similarly defined as piezoelectric element unit group A. When drive voltages are applied in parallel to the piezoelectric element unit group A, as shown in FIG. 2(ii), the piezoelectric element unit group A bends and deforms in the same direction, and the mirror unit 101 moves around the second axis in the -Z direction.

Of the multiple second drive units 131a to 131d that the second drive structure unit 130a has, the odd-numbered second drive units, counting from the second drive unit (131a) that is closest to the mirror unit, i.e., the second drive units 131a and 131c, are defined as piezoelectric element unit group B. Furthermore, of the multiple second drive units 132a to 132d that the second drive structure unit 130b has, the even-numbered second drive units, counting from the second drive unit (132a) that is closest to the mirror unit, i.e., 132b and 132d, are similarly defined as piezoelectric element unit group B. When drive voltages are applied in parallel to the piezoelectric element unit group B, as shown in FIG. 2(iv), the piezoelectric element unit group B bends and deforms in the same direction, and the mirror unit 101 moves around the second axis in the +Z direction.

2 (ii) and (iv), in the second drive structure 130a or 130b, the multiple piezoelectric parts 202 of the piezoelectric element part group A or the multiple piezoelectric parts 202 of the piezoelectric element part group B are simultaneously bent and deformed, so that the amount of movement due to the bending deformation can be accumulated and the deflection angle of the mirror part 101 around the second axis can be increased. For example, as shown in FIG. 1, the second drive structure 130a, 130b is connected to the first support part in point symmetry with respect to the center point of the first support part. Therefore, when a drive voltage is applied to the piezoelectric element part group A, the second drive structure 130a generates a driving force at the connection part between the first support part and the second drive structure 130a to move in the +Z direction, and the second drive structure 130b generates a driving force at the connection part between the first support part and the second drive structure 130b to move in the -Z direction, and the amount of movement is accumulated to increase the deflection angle of the mirror part 101 around the second axis.

Also, as shown in FIG. 2 (iii), when the amount of movement of the mirror section 101 caused by the piezoelectric element group A due to the application of voltage is balanced with the amount of movement of the mirror section 101 caused by the piezoelectric drive group B due to the application of voltage, the deflection angle is zero.

By applying a drive voltage to the second drive unit so as to continuously repeat Figures 2(ii) to 2(iv), the mirror unit can be driven around the second axis.

The drive voltage applied to the second drive structure is controlled by the control device.

The drive voltage applied to the piezoelectric element group A (hereinafter, drive voltage A) and the drive voltage applied to the piezoelectric element group B (hereinafter, drive voltage B) are explained using FIG. 3.

As shown in FIG. 3(a), the drive voltage A applied to the group of piezoelectric element parts A is, for example, a sawtooth waveform drive voltage, and has a frequency of, for example, 60 Hz. In addition, the waveform of the drive voltage A is preset to a ratio of, for example, TrA:TfA=9:1, where TrA is the duration of the rise period during which the voltage value increases from a minimum value to the next maximum value, and TfA is the duration of the fall period during which the voltage value decreases from a maximum value to the next minimum value. In this case, the ratio of TrA to one period is called the symmetry of the drive voltage A.

As shown in FIG. 3B, the drive voltage B applied to the piezoelectric element group B is, for example, a sawtooth waveform drive voltage, and the frequency is, for example, 60 Hz. In addition, the waveform of the drive voltage B is preset to a ratio of, for example, TfB:TrB=9:1, where TrB is the duration of the rise period during which the voltage value increases from the minimum value to the next maximum value, and TfB is the duration of the fall period during which the voltage value decreases from the maximum value to the next minimum value. In this case, the ratio of TfB to one period is called the symmetry of the drive voltage B. In addition, as shown in FIG. 3C, for example, the period TA of the waveform of the drive voltage A and the period TB of the waveform of the drive voltage B are set to be the same.

The sawtooth waveforms of the drive voltages A and B are generated by superimposing sine waves. In this embodiment, drive voltages with sawtooth waveforms are used as drive voltages A and B, but the waveforms can be changed according to the device characteristics of the movable device, such as a drive voltage with rounded peaks of a sawtooth waveform or a drive voltage with a waveform in which the linear regions of the sawtooth waveform are curved.

The reason why the sub-scanning is rotated in a non-resonant manner in this way is that if it were to operate in a resonant manner like the main scanning, the scanning lines would not be spaced equally and image quality would deteriorate. When operating in a non-resonant manner, the resonant frequency of the rotation mode about the second axis must be designed to be sufficiently higher than the drive frequency.

As mentioned above, in this embodiment, the main scanning structure is configured three-dimensionally, and the moment of inertia can be reduced, making it easy to increase the primary resonance frequency of the sub-scanning. In recent years, there has been a strong demand for larger mirror sizes, which has led to larger main scanning structures, but by using this embodiment, it is possible to prevent a decrease in the resonance frequency.

In addition, when it is necessary to increase the amplitude of the sub-scanning, the amplitude can be increased by lowering the rigidity of the sub-scanning structure, but this lowers the primary resonance frequency of the sub-scanning. Even in such cases, it is possible to increase the amplitude of the sub-scanning while maintaining the resonance frequency by using this embodiment.

Second Embodiment
A second embodiment of the present invention is shown in Fig. 4. Fig. 4A is a front view, Fig. 4B is a rear view, and Figs. 4C to 4F are cross-sectional views.

The basic configuration is the same as in the first embodiment. The difference from the first embodiment is the form of connection between the drive unit and the torsion bar spring. The positions of the drive unit connections 113a, 113b shown in FIG. 4B are different. In this embodiment, the drive unit connections 113a, 113b are disposed at the +Y-axis ends of the drive units 111a, 111b. That is, in the second embodiment, the length of the drive unit in the Y direction is longer than in the first embodiment, and the entire inside of the first support unit 120 is utilized.

Figure 4D shows this folding back in cross section. In the cross section D-D', the driving unit 112a and the coupling unit 111a are connected by the driving unit connection part 113a. The silicon active layer 362c and the silicon active layer 361c in which the driving unit is formed are connected with the silicon support layer 361a sandwiched between them. The driving unit is connected in a folded-back manner to the fixed end side of the driving unit, and is connected to the torsion bar springs 111a and 111b via the driving unit connection parts 113a and 113b approximately near the central axis of the mirror. The driving unit connection parts 113a and 113b are formed from the silicon active layer 362c, which is thicker than the silicon active layer 361c, and are folded back with almost no deformation.

In FIG. 4B, the distance relationship between each of the main components is as follows. The length of the torsion bar spring between the movable part 102 and the driving part 112a is L2. In this case, the length of L2 indicates the path from the junction region 113b, passing through the D-D' line, bending at the intersection of E-E', and reaching the mirror part connection part 104. The mirror part connection part is formed of the silicon active layer 362c of the second SOI substrate.

The distance between the movable part 102 and the drive parts 112a and 112b is L3. The drive parts are formed at a fixed distance so as to surround the circumference of the movable part. This is because the drive force increases when the area is as large as possible. In other words, the distance is set to prevent contact with the movable part via a fixed distance L3.

When the movable part, drive part and connecting part are formed on a flat surface, the connecting part has a length of L3. In contrast, in this embodiment, the length of L2 mentioned above can be considered the connecting part. L2 is much longer, and by overlapping the movable part and connecting part while maintaining the spring constant, it is possible to realize the smallest possible movable device.

Figure 4F shows a conceptual diagram of the driver at cross section D-D' (Figure 4D) during deformation. A space is formed between the driver and the torsion bar spring, and this space is released toward the joint with the first support. In the figure, it is in the -Y direction. This cancels out the Z displacement 570 at the tip of the driver, and the ratio of the rotational component to the Z-direction amplitude component is high near the central axis of the torsion bar spring (410, 410), making it easier to obtain a pure moment. When displaced, the central axis 410 of the torsion bar spring becomes the central axis (displacement position) 411 of the torsion bar spring, which can be seen to be smaller than the Z-direction amplitude component 570 at the tip.

In Figures 4A and 4B, the central axis of the mirror and the central axis of the torsion bar spring are approximately aligned. In other words, axis 530 and the line E-E' are approximately aligned. The folded length of the drive unit connection part may be adjusted to minimize the Z component of the difference between axis 530 and the central axis of the torsion bar spring. In this way, in the second embodiment, the amplitude can be increased by maximizing the area of the first drive unit.

[Third embodiment]
A third embodiment of the present invention is shown in Fig. 5. Fig. 5A is a front view, Fig. 5B is a rear view, and Figs. 5C to 5E are cross-sectional views.
The basic configuration is the same as in the first and second embodiments. In this embodiment, piezoelectric members 116a and 116b for detection are formed at the connection portion between the drive unit and the torsion bar spring so that the amplitude of the main scanning can be detected.

The folded structure at the connection part is similar to that of the second embodiment, but the actuator part formed of silicon active layer 361c is separated by a slit (Y direction) 550, and the silicon support layer 361a is left as is, so that the folded part does not deform. The actuator part is L-shaped, separated by a slit (X direction) 560 and a slit (Y direction) 550, and forms a free end (Figure 5A). The slit (X direction) is clearly indicated on the cross section of Figure 5D.

However, in the area where the detection piezoelectric elements 116a and 116b are arranged, the silicon support layer 361a is separated to form an area of only the silicon active layer 361c, which makes it easier to deform, and thereby a detection signal corresponding to the twist of the torsion bar spring according to the amplitude of the mirror part can be obtained.

[Fourth embodiment]
<Configuration of movable device>
The fourth embodiment is shown in Fig. 6. Fig. 6A is a front view, Fig. 6B is a rear view, and Fig. 6C to Fig. 6E are cross-sectional views, respectively. However, Fig. 6B is a half cross-sectional view taken along the line CC'.

The fourth to sixth embodiments differ from the first to third embodiments in the substrate configuration.
As shown in Figure 6, the movable device 13 has a mirror portion 101 that reflects incident light, first drive structure portions 110a, 110b connected to the mirror portion and driving the mirror portion around a first axis parallel to the Y axis, a first support portion 120 that supports the mirror portion and the first drive structure portion, second drive structure portions 130a, 130b connected to the first support portion and driving the mirror portion and the first support portion around a second axis parallel to the X axis, a second support portion 140 that supports the second drive structure portion, and an electrode connection portion 150 that is electrically connected to the first drive structure portion, the second drive structure portion, and a control device.

The movable device 13 is formed, for example, by bonding two SOI (Silicon On Insulator) substrates, a first SOI substrate 361 and a second SOI substrate 362, with a silicon oxide layer 363 sandwiched between them.

The first SOI substrate is formed of a silicon support layer 361a, a silicon oxide layer 361b, and a silicon active layer 361c, and the second SOI substrate is formed of a silicon support layer 362a, a silicon oxide layer 362b, and a silicon active layer 362c.

In the first to third embodiments, the bonding surface is the silicon support layer 361a of the first SOI substrate 361 and the silicon active layer 362c of the second SOI substrate 362, whereas in the fourth to sixth embodiments, the bonding surface is the silicon support layer 361a of the first SOI substrate 361 and the silicon support layer 362c of the second SOI substrate 362. In other words, the second SOI substrate 362 is inverted.

Each SOI substrate is shaped by etching or the like, and the reflective surface 14, first drive units 112a, 112b, second drive units 131a-131d, 132a-132d, electrode connection unit 150, etc. are formed on the shaped substrate, so that each component is integrally formed. Note that the formation of each of the above components may be performed after the SOI substrate is shaped, or may be performed while the SOI substrate is being shaped.

The SOI substrate does not necessarily have to be planar, and may have curvature, etc. Also, the material used to form the movable device 13 is not limited to the SOI substrate, as long as it can be integrally molded by etching or the like and can be made partially elastic.

Next, the main scanning structure for rotating about the first axis will be described in detail.
The mirror section 101 is composed of, for example, a circular mirror section base 102 and a reflecting surface 14 formed on the -Z side surface of the mirror section base. The mirror section base 102 is composed of, for example, a silicon active layer 362c. The reflecting surface 14 is composed of, for example, a metal thin film containing aluminum, gold, silver, or the like.

Unlike the first to third embodiments, the mirror section 101 is formed with the rear surface serving as a reflective surface.
6B, the mirror section 101 may have a rib 103 for reinforcing the mirror section formed on the −Z side surface of the mirror section base 102. The rib is made of, for example, a silicon support layer 362a and a silicon oxide layer 362b, and can suppress distortion of the reflecting surface 14 that occurs when the mirror oscillates.

The first drive structure 110a, 110b is composed of a first drive section 112a, 112b made of a silicon active layer 361c, and a first piezoelectric element section. Drive section ribs 114a, 114b and drive section connection sections 113a, 113b (described later) are formed on the back surface of the first drive section 112a, 112b. The stiffness is designed by the shape and width of the drive section ribs 114a, 114b, and the resonance frequency of the drive section is set to a desired value.
One end of each of the drive portions 112 a and 112 b is connected to a torsion bar spring, which will be described later, and the other end is connected to the inner periphery of the first support portion 120 .

The first driving units 112a and 112b are configured by forming a lower electrode 201, a piezoelectric unit 202, and an upper electrode 203 in this order on the +Z side surface of the silicon active layer 361c, which is the elastic unit, as shown in FIG. 6e. The upper electrode 203 and the lower electrode 201 are made of, for example, gold (Au) or platinum (Pt). The piezoelectric unit 202 is made of, for example, PZT (lead zirconate titanate), which is a piezoelectric material.

As shown in FIG. 6B, the torsion bar springs 111a and 111b are configured from the silicon active layer 361a of the first SOI substrate 361 with the first axis direction as the longitudinal direction.

The torsion bar springs 111a, 111b each have one end connected to the mirror section rib 103 via the mirror connection section 104, and the other end connected to the first drive structure sections 110a, 110b via the drive section connection sections 113a, 113b, supporting the mirror section 101 in a rotatable manner.

As shown in Fig. 6B, the torsion bar spring has its torsion central axis offset (dS) from the center of the mirror, so that the amplitude in the Z direction at the tip of the driver is converted into a rotational force (moment) to rotate the mirror. Since the tip of the driver is a free end, a large amplitude can be obtained without interfering with the piezoelectric driving force.
Furthermore, by setting the bending mode resonance of the drive section close to the mirror resonance (the torsion mode resonance of the torsion bar spring), the rotation angle of the mirror can be greatly increased, enabling large amplitude operation with a low applied voltage.

Returning to FIG. 6A, the first support unit 120 is, for example, a support having a substantially rectangular shape and made up of a silicon support layer 361a, a silicon oxide layer 361b, and a silicon active layer 361c, and is formed to surround the mirror unit 101 and the first drive units 112a and 112b.

In this way, the torsion bar spring and drive section are formed from the silicon active layer 361c and/or silicon support layer 361a of the first SOI substrate, and the mirror section is formed from the second SOI substrate 362c. By stacking these three-dimensionally with a gap of the thickness of the first silicon support layer 362c and configuring them compactly, the moment of inertia of the main scanning structure can be reduced.

The structure of the sub-scanning for rotating around the second axis and the details of the control of the control device are the same as those in the first to third embodiments.

[Fifth embodiment]
A fifth embodiment of the present invention is shown in Fig. 7. Fig. 7A is a front view, Fig. 7B is a rear view, and Figs. 7C to 7E are cross-sectional views.

The basic configuration is the same as in the fourth embodiment.

The fifth embodiment is an embodiment in which the mirror size is even larger. As shown in FIG. 7, the mirror portion is formed to be slightly larger than the main scanning structure, and is larger than the first support portion 120. Since the first support portion is formed from a thick silicon support layer, the size of the first support portion has a large effect on the moment of inertia.

By forming the first support section 120 small relative to the size of the mirror section as in this embodiment, it is possible to keep the moment of inertia small. In this embodiment, the rib 103 of the mirror section and the first support section or drive section ribs 114a, 114b and the torsion bar spring 112 are arranged so as not to overlap in the Z direction. This prevents them from interfering with each other when deforming in the Z direction during operation.

Sixth embodiment
The sixth embodiment is shown in Fig. 8. Fig. 8A is a front view, Fig. 8B is a rear view, and Figs. 8C to 8E are cross-sectional views.

The basic configuration is the same as in the fourth and fifth embodiments.

The sixth embodiment is similar to the fifth embodiment in that the mirror size is large.

As shown in FIG. 8D, the mirror 14 and the driver 112b overlap in the field of view in the Z direction. As shown in FIG. 8E, a space 580 is formed between the torsion bar spring 111a and the mirror 14. The space 580 is open from the connection 570 in the -X direction. This means that it is open in the direction of the connection 570 between the driver 112b and the torsion bar spring 111a. The torsion bar spring has a substantial length in the opening direction of the space 580, and the spring constant can be secured. As a result, even if the mirror 14 expands, the driver 112b and the mirror part 14 overlap, and compactness can be achieved. At this time, the torsion bar spring 111b maintains its spring constant due to the space 580, and the deflection angle can be maintained.

In the sixth embodiment, as in the fifth embodiment, the moment of inertia can be kept small by forming the first support 120 small relative to the size of the mirror section. Furthermore, by making the moment of inertia of the first support around the X axis larger relative to the moment of inertia around the Y axis, it is possible to suppress vibration of the first support without lowering the primary resonance frequency of the sub-scanning. Specifically, by increasing the frame width of the first support only in a position near the center of the second axis and away from the center of the first axis, the moment of inertia around the first axis is increased while suppressing the moment of inertia around the second axis.

When the rigidity of the support system for the second axis (sub-scanning structure) around the first axis is low, abnormal operation can be suppressed by making the moment of inertia around one axis of the first support section 120 larger than the moment of inertia of the mirror section.

The following describes an embodiment in which the optical deflector of the present invention is applied to an application.

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

Figure 9 shows a schematic diagram of an example of an optical scanning system. As shown in Figure 9, the optical scanning system 10 is a system that deflects light irradiated from a light source device 12 by a reflecting surface 14 of a movable device 13 under the control of a control device 11 to optically scan a scanned surface 15.

The optical scanning system 10 is composed of a control device 11, a light source device 12, and a movable device 13 having a reflective surface 14.

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

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

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

As a result, for example, by controlling the control device 11 based on image information, which is an example of optical scanning information, the reflective surface 14 of the movable device 13 can be moved back and forth in two axial directions within a predetermined range, and the irradiation light from the light source device 12 that is incident on the reflective surface 14 can be deflected around a certain axis to perform optical scanning, thereby projecting any image onto the scanned surface 15. Details of the movable device of this embodiment and the control by the control device will be described later.

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

The CPU 20 is a calculation device that reads programs and data from storage devices such as the ROM 22 onto the RAM 21, executes processing, and realizes the overall control and functions of the control device 11.

RAM21 is a volatile storage device that temporarily stores programs and data.

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

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

The external I/F 24 is, for example, an interface with an external device, a network, etc. The external device includes, for example, a higher-level device such as a PC (Personal Computer), and a storage device such as a USB memory, an SD card, a CD, a DVD, a HDD, and an SSD. The network is, for example, a controller area network (CAN) or a local area network (LAN) of an automobile, the Internet, etc. The external I/F 24 may have any configuration that enables connection or communication with an external device, and an external I/F 24 may be provided for each external device.

The light source device driver is an electric circuit that outputs a drive signal, such as a drive voltage, to the light source device 12 in accordance with an input control signal.

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

In the control device 11, the CPU 20 acquires optical scanning information from an external device or a network via the external I/F 24. Note that any configuration is acceptable as long as the CPU 20 is capable of acquiring optical scanning information, and the optical scanning information may be stored in the ROM 22 or FPGA 23 in the control device 11, or a new storage device such as an SSD may be provided in the control device 11, and the optical scanning information may be stored in that storage device.

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

The control device 11 can realize the functional configuration described below by using instructions from the CPU 20 and the hardware configuration shown in FIG. 10.

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

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

The control unit 30 is realized by, for example, the CPU 20, FPGA 23, etc., and acquires optical scanning information from an external device, converts the optical scanning information into a control signal, and outputs it to the drive signal output unit 31. For example, the control unit 30 acquires image data from an external device, etc. as optical scanning information, generates a control signal from the image data by performing a predetermined process, and outputs it to the drive signal output unit 31. The drive signal output unit 31 is realized by the light source device driver 25, movable device driver 26, etc., and outputs a drive signal to the light source device 12 or movable 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 movable device 13. For example, in the light source device 12, it is a drive voltage that controls the timing and intensity of the light source irradiation. Also, for example, in the movable device 13, it is a drive voltage that controls the timing and range of movement of the reflective surface 14 of the movable device 13.

Next, the process of optically scanning the surface 15 to be scanned by the optical scanning system 10 will be described with reference to FIG. 12. FIG. 12 is a flowchart of an example of the process related to the optical scanning system.

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

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

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

In step 14, the light source device 12 emits light based on the input drive signal. The movable device 13 moves the reflecting surface 14 based on the input drive signal. By driving the light source device 12 and the movable device 13, the light is deflected in any direction and optically scanned.

In the optical scanning system 10, one control device 11 has the devices and functions to control the light source device 12 and the movable device 13, but the control device for the light source device and the control device for the movable device may be provided separately.

In addition, in the optical scanning system 10, one control device 11 is provided with the functions of the control unit 30 of the light source device 12 and the movable device 13 and the function of the drive signal output unit 31, but these functions may exist separately, for example, a drive signal output device having a drive signal output unit 31 may be provided separately from the control device 11 having the control unit 30. Note that, in the optical scanning system 10, the movable device 13 having the reflective surface 14 and the control device 11 may form an optical deflection system that performs optical deflection.

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

Figure 13 is a schematic diagram of an embodiment of an automobile 400 equipped with a head-up display device 500, which is an example of an image projection device. Also, Figure 14 is a schematic diagram of an example of the head-up display device 500.

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

As shown in FIG. 13, the head-up display device 500 is installed, for example, near the windshield (windshield 401, etc.) of the automobile 400. The projected light L emitted from the head-up display device 500 is reflected by the windshield 401 and directed toward the observer (driver 402), who is the user. This allows the driver 402 to view the image projected by the head-up display device 500 as a virtual image. Note that a combiner may be installed on the inner wall surface of the windshield, and the projected light reflected by the combiner may be configured to allow the user to view a virtual image.

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

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

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

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

The above describes the head-up display device 500 as an example of an image projection device, but the image projection device may be any device that projects an image by performing optical scanning with a movable device 13 having a reflective surface 14. For example, the present invention can be similarly applied to a projector that is placed on a desk or the like and projects an image onto a display screen, or a head-mounted display device that is mounted on a mounting member that is attached to the observer's head or the like and projects an image onto a reflective/transmissive screen of the mounting member, or projects an image using the eyeball as a screen.

The image projection device may be mounted not only on a vehicle or a mounting member, but also on a moving body such as an aircraft, a ship, or a mobile robot, or on a non-moving body such as a work robot that operates a drive target such as a manipulator without moving from its location.

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

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

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

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

As shown in FIG. 16, in the optical writing device 600, the laser light from the light source device 12 such as a laser element passes through an imaging optical system 601 such as a collimator lens, and is then deflected in one or two axial directions by a movable device 13 having a reflective surface 14. The laser light deflected by the movable device 13 then passes through a scanning optical system 602 consisting of a first lens 602a, a second lens 602b, and a reflective mirror section 602c, and is irradiated onto a scanned surface 15 (e.g., a photosensitive drum or photosensitive paper) to perform optical writing. The scanning optical system 602 forms a spot-shaped light beam on the scanned surface 15. In addition, the light source device 12 and the movable device 13 having the reflective surface 14 are driven under the control of the control device 11.

In this way, the optical writing device 600 can be used as a component of an image forming device having a printer function using laser light. In addition, by changing the scanning optical system to enable optical scanning not only in one axis direction but also in two axes directions, it can be used as a component of an image forming device such as a laser label device that deflects laser light onto thermal media, optically scans it, and prints by heating it.

The movable device 13 having a reflective surface 14 applied to the optical writing device described above consumes less power to operate than a rotating polygon mirror using a polygon mirror or the like, which is advantageous for reducing the power consumption of the optical writing device. In addition, the wind noise generated when the movable device 13 vibrates is smaller than that of a rotating polygon mirror, which is advantageous for improving the quietness of the optical writing device. The optical writing device requires far less installation space than a rotating polygon mirror, and the movable device 13 generates only a small amount of heat, making it easy to miniaturize the device, which is advantageous for miniaturizing the image forming device.

[Object Recognition Device]
Next, an object recognition device to which the movable device of the present embodiment is applied will be described in detail with reference to FIGS. 17 and 18. FIG.

Figure 17 is a schematic diagram of an automobile equipped with a LiDAR (Laser Imaging Detection and Ranging) device, which is an example of an object recognition device. It is a schematic diagram of an automobile equipped with a LiDAR device in a lamp unit that mounts the automobile's headlights. Also, Figure 18 is a schematic diagram of an example of a LiDAR device.

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

As shown in FIG. 17, the lidar device 700 is mounted on, for example, an automobile 701, and recognizes an object 702 by optically scanning the target direction and receiving reflected light from the object 702 present in the target direction.

As shown in FIG. 18, the laser light emitted from the light source device 12 passes through an incident optical system consisting of a collimator lens 703, which is an optical system that converts divergent light into approximately parallel light, and a plane mirror 704, and is scanned in one or two axial directions by a movable device 13 having a reflecting surface 14. Then, it is irradiated onto an object 702 in front of the device through a projection lens 705, which is a projection optical system. The light source device 12 and the movable device 13 are controlled by the control device 11. The reflected light reflected by the object 702 is optically detected by a photodetector 709. That is, the reflected light passes through a condenser lens 706, which is an incident light detection and light receiving optical system, and is received by an image sensor 707, which outputs a detection signal to a signal processing circuit 708. The signal processing circuit 708 performs predetermined processing such as binarization and noise processing on the input detection signal, and outputs the result to a distance measurement circuit 710.

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

The movable device 13 with the reflective surface 14 is less likely to break than a polygonal mirror and is small, making it possible to provide a small, highly durable radar device. Such a lidar device can be attached to, for example, a vehicle, an aircraft, a ship, a robot, etc., and can optically scan a specified range to determine the presence or absence of an obstacle and the distance to the obstacle.

The above object recognition device has been described as an example of a lidar device 700, but the object recognition device may be any device that performs optical scanning by controlling a movable device 13 having a reflective surface 14 with a control device 11, and recognizes an object 702 by receiving reflected light with a photodetector, and is not limited to the above-mentioned embodiment.

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

[Laser headlamp]
Next, a laser headlamp 50 in which the movable device of the present embodiment is applied to an automobile headlight will be described with reference to Fig. 19. Fig. 19 is a schematic diagram for explaining an example of the configuration of the laser headlamp 50.

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

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

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

The scanning light from the movable device 13 scatters in a certain way as it passes through the phosphor in the transparent plate 52. This reduces glare on the illuminated object in front of the vehicle.

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

[Head-mounted display]
Next, a head mounted display 60 to which the movable device of the present embodiment is applied will be described with reference to Figures 20 to 21. Here, the head mounted display 60 is a head mounted display that can be mounted on a human head, and can have a shape similar to glasses, for example. The head mounted display will be abbreviated to HMD hereinafter.

Figure 20 is a perspective view illustrating the appearance of the HMD 60. In Figure 20, the HMD 60 is composed of a front 60a and temples 60b, which are provided approximately symmetrically on the left and right. The front 60a can be composed of, for example, a light guide plate 61, and the optical system, control device, etc. can be built into the temples 60b.

Figure 21 is a diagram illustrating a partial configuration of the HMD 60. Note that while Figure 21 illustrates a configuration for the left eye, the HMD 60 has a similar configuration for the right eye.

The HMD 60 has a control device 11, a light source unit 530, a light amount adjustment unit 507, a movable device 13 having a reflective surface 14, a light guide plate 61, and a half mirror 62.

As described above, the light source unit 530 is a unit made up of the laser light sources 501R, 501G, and 501B, the collimator lenses 502, 503, and 504, and the dichroic mirrors 505 and 506, all of which are enclosed in an optical housing. In the light source unit 530, the three color laser beams from the laser light sources 501R, 501G, and 501B are combined by the dichroic mirrors 505 and 506. The combined parallel light is emitted from the light source unit 530.

The light from the light source unit 530 is adjusted in amount by the light amount adjustment unit 507 and then enters the movable device 13. The movable device 13 moves the reflecting surface 14 in the XY directions based on a signal from the control device 11, and performs two-dimensional scanning with the light from the light source unit 530. The drive control of this movable device 13 is performed in synchronization with the emission timing of the laser light sources 501R, 501G, and 501B, and a color image is formed by the scanning light.

The scanning light from the movable device 13 enters the light guide plate 61. The light guide plate 61 guides the scanning light to the half mirror 62 while reflecting it on 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.

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

Since 62 is a half mirror, the image produced by the light from the outside world and the image produced by the scanning light are superimposed on each other and observed by the wearer 63. By providing a mirror instead of the half mirror 62, it is possible to eliminate the light from the outside world and to configure the wearer 63 to be able to observe only the image produced by the scanning light.

As described above, the aspects of the present invention are as follows:

＜1＞
A movable device according to one embodiment of the present invention has a movable part, a driving part that drives the movable part, and a connecting part that connects the movable part and the driving part, wherein the connecting part has a gap in an area that overlaps with at least one of the movable part and the driving part in a planar view, and the length of the connecting part between the connection position with the movable part and the connection position with the driving part, excluding the connection area between the movable part and the driving part in a planar view, is longer than the distance between the driving part and the movable part in a planar view.

This allows the movable device to be made more compact than before by the area where the connecting part and the drive part overlap, without changing the actual length of the connecting part. The length of the connecting part is proportional to the spring constant, so if the length is the same, the spring constant is the same, and a compact movable device can be provided while maintaining the same amplitude and frequency of the movable part.

＜2＞
The movable device according to one embodiment of the present invention has the feature described in <1>, in which the drive unit and the movable unit overlap in the plan view. This allows the movable device to be formed more compactly than before by the area where the movable unit and the connecting unit overlap.

＜3＞
The movable device according to one embodiment of the present invention has the feature described in <1> or <2>, in which the drive unit rotates the movable unit, and the connecting unit in a plan view extends from a connection position with the movable unit in a direction parallel to the axis of the rotation. This makes it possible to form a movable device that is more compact than conventional devices by an area where the movable unit and the connecting unit overlap.

＜4＞
The movable device according to one embodiment of the present invention has the features described in <1> to <3>, in which the drive unit rotates the movable unit, and the connecting unit in a plan view extends from a connection position with the drive unit in a direction intersecting the axis of the rotation. This makes it possible to form a movable device that is more compact than conventional devices by the area where the movable unit and the connecting unit overlap.

＜5＞
A movable device according to one embodiment of the present invention has a first support part for fixing the drive part, another drive part connected to the first support part and driving the first support part, a second support part for fixing the other drive part, a first axis for rotating the movable part by the drive part and a second axis for rotating the movable part by the other drive part that are substantially perpendicular to each other, and has the features described in <1> to <4>.

This allows the structure of the first axis (the main scanning direction in the optical deflector shown in the embodiment) to be formed compactly. Because it is a compact structure, the moment of inertia is small. This allows the primary resonance frequency of the second axis, the sub-scanning, to be increased.

Conventionally, when the drive unit, the connecting unit, and the movable unit are each configured in a planar manner, the area of the structure becomes large, and the distance from the sub-scanning rotation center increases, causing a sudden increase in the moment of inertia. The moment of inertia can be reduced by stacking the components of the optical deflector. By reducing the moment of inertia of the main scanning structure (i.e., the movable unit relative to the sub-scanning), the primary resonance frequency of the sub-scanning can be increased. In addition, if the primary resonance frequency is sufficiently high, the amplitude can be increased instead of increasing the resonance frequency by designing the support rigidity in the scanning direction of the sub-scanning to be small. Since the commonly used SOI substrate has a two-layer structure, it was not possible to stack the components in this way, but it has become possible to use three- or four-layer substrates as structures due to advances in bonding and mounting technologies in the manufacturing process.

＜6＞
The movable device according to one embodiment of the present invention has the features described in <1> to <5>, in which a slit is formed in the driving section, the connecting section is connected at a position where the driving section is folded back toward the first support section, and an area having a piezoelectric detection function is formed in the area on the side of the smaller area of the driving section divided by the slit.

This has the effect of increasing the amplitude of the drive section in the detection unit and improving the detection feeling. By improving the sensitivity, controllability is improved, making it possible to drive the moving section accurately even in a moving device that is smaller than before.

＜７＞
The movable device according to one embodiment of the present invention has the features described in <1> to <6>, in which a rib is formed on the back surface of the movable part, and the drive part and the connecting part are arranged so as not to overlap. This has the effect of ensuring a range of motion while suppressing surface deformation. This makes it possible to make a movable device even smaller than before.

＜8＞
The movable device according to one embodiment of the present invention has the feature described in <1> or <2>, in which the moment of inertia about the first axis of the first support part and the first drive part is larger than the moment of inertia about the first axis of the movable part.

This has the effect of suppressing vibrations in the first support part that occur when the first axis operates. This makes it possible to create an even smaller movable device than before.

＜9＞
A movable device according to one embodiment of the present invention is a movable device having a movable part, a driving part that drives the movable part, and a connecting part that connects the movable part and the driving part, and is characterized in that, in a planar view, it has a region where the driving part and the connecting part overlap, and the region includes a space between the driving part and the connecting part that is open to the movable part side.

This allows the movable device to be made more compact than before by the area where the connecting part and the drive part overlap, without changing the actual length of the connecting part. The length of the connecting part is proportional to the spring constant, so if the length is the same, the spring constant is the same, and a compact movable device can be provided while maintaining the same amplitude and frequency of the movable part.

＜10＞
The movable device according to one embodiment of the present invention has the feature described in <9>, in which the space between the drive section and the connection section is open toward the support section of the drive section.

As a result, the connecting portion is positioned at the free end with the larger driving width, resulting in an arrangement in which the overlapping connecting portions extend so as to fold back toward the fixed end. By folding back, fluctuations in the substrate thickness direction caused by deflection of the driving portion can be eliminated, and the rotational component (moment) can be efficiently transmitted to the elastic support member. In addition, increasing the area of the driving portion has the effect of increasing the driving amplitude. By folding back, fluctuations in the substrate thickness direction caused by deflection of the driving portion can be eliminated, and the rotational component (moment) can be efficiently transmitted to the elastic support member. In addition, increasing the area of the driving portion has the effect of increasing the driving amplitude.

10 Optical scanning system 11 Control device 12 Light source device 13 Movable device 14 Reflecting surface 15 Scanned surface 30 Control unit (one example of a control means)
31 Drive signal output unit (an example of an application means)
101 Mirror portion 102 Mirror base 103 Mirror portion rib 104 Mirror portion connection portion 110a, 110b First drive structure portion a, b
111a, b Torsion bar spring a, b
112a, 112b First drive section 113a, 113b Drive section connection section 114a, 114b Drive section rib 120 First support section 130a, 130b Second drive structure section 131a to 131d Second drive section a
132a to 132d Second driving section b
140 Second support portion 150 Electrode connection portion 361 Silicon support layer 362 Silicon oxide layer 363 Silicon active layer 201 Lower electrode 202 Piezoelectric portion 203 Upper electrode 400 Automobile 410 Torsion center 411 Torsion center (displacement position)
500 Head-up display device (image projection device)
501 L1 (distance between the movable part and the drive part and the connecting part)
502 L2 (length of space formed between the movable part, the driving part and the connecting part)
503 L3 (distance between moving part and driving part)
510 Piezoelectric element group A
520 Piezoelectric element group B
530: First shaft 540: Second shaft 550: Slit portion of the drive portion (Y direction)
560 Slit part of drive part (X direction)
570 Z-direction amplitude 580 Space 590 Connection area (connection between drive part and coupling part)
591 Connection area (connection between movable part and connecting part)
600 Optical writing device 650 Laser printer (image forming device)
700 Laser radar device (object recognition device)

<Correspondence between terms in the embodiments and terms in the claims>
The drive signal output unit 31 is an example of an "applying unit." The control unit 30 is an example of a "controlling unit."

Claims (15)

A movable part;
A drive unit that drives the movable unit;
a connecting portion that connects the movable portion and the driving portion,
the connecting portion has a gap in a region overlapping with at least one of the movable portion and the driving portion in a plan view,
A movable device characterized in that the length of the connection portion between the connection position with the movable part and the connection position with the drive part, excluding the connection area with the movable part and the drive part in a planar view, is longer than the distance between the drive part and the movable part in a planar view. The movable device according to claim 1 , wherein the drive section and the movable section overlap each other in the plan view. The drive unit rotates the movable unit,
The movable device according to claim 1 or 2, wherein the connecting portion in a plan view extends in a direction parallel to the axis of rotation from a connection position with the movable portion. The drive unit rotates the movable unit,
The movable device according to claim 1 or 2, wherein the connecting portion in a plan view extends from a connection position with the driving portion in a direction intersecting the axis of rotation. a first support portion for fixing the driving portion;
There is another drive unit connected to the first support unit and driving the first support unit,
a second support portion for fixing the other driving portion;
With respect to a first axis that rotates the movable part by the drive part,
3. The movable device according to claim 1, wherein the second axis rotated by the other driving portion is substantially perpendicular to the first axis. The drive section has a slit,
The coupling portion is connected to the driving portion at a position where the driving portion is folded back toward the first support portion,
3. The movable device according to claim 1, wherein a region having a piezoelectric detection function is formed in a region on the side of the smaller area of the driving portion divided by the slit. A rib is formed on the back surface of the movable portion,
3. The movable device according to claim 1, wherein the drive portion and the connecting portion are arranged so as not to overlap each other. 3. The movable device according to claim 1, wherein a moment of inertia of the first support portion and the first drive portion about the first axis is greater than a moment of inertia of the movable portion about the first axis. 3. The movable device according to claim 1, wherein the movable portion is larger than the first support portion and smaller than the second support portion. An image projection device having the movable device according to claim 1. A head-up display comprising the movable device according to claim 1. A laser headlamp comprising the movable device according to claim 1. A head-mounted display comprising the movable device according to claim 1. An object recognition device comprising the movable device according to claim 1. A moving object having at least one of the head-up display according to claim 11, the laser headlamp according to claim 12, and the object recognition device according to claim 14.