JP2013076984A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a change in scanning characteristics due to temperature change in an optical scanner using torsional vibration.SOLUTION: The optical scanner includes a mirror 31 having a reflection surface for reflecting the rays of light and an elastic connection parts 16a and 16b as a rotational axis k for making the mirror 31 generate torsional vibration, and scans the rays of light by oscillating the mirror 31 with the rotational axis k as a center. Then, a mirror support frame 32 and a heat actuator 33 connect the mirror 31 with the elastic connection parts 16a and 16b, and displace the mirror 31 such that according as temperature rises, an inertia moment around the rotational axis k of the mirror 31 falls. Also, the reflection surface of the mirror 31 has any shape(elliptical shape in figure) other than a circular shape in order to change the inertia moment of the mirror 31, and the heat actuator 33 rotates the mirror 31 with the rotational axis which is vertical to the reflection surface as a center.

Description

  The present invention relates to an optical scanning device that scans a light beam.

In recent years, various optical scanning devices using MEMS (Micro Electro Mechanical System) technology have been proposed for the purpose of downsizing the optical scanning device.
In contrast, the applicant of the present application provides a third frame having a reflective surface formed on the surface, a second frame provided with a predetermined gap with respect to the third frame, and a predetermined gap with respect to the second frame. And a 0th frame provided with a predetermined gap with respect to the first frame, and the third frame, the second frame, and the first frame are respectively connected to the respective rotation shafts. An optical scanning device having a three-degree-of-freedom coupled vibration system has been proposed (see, for example, Patent Document 1).

  In the optical scanning device configured as described above, the three-degree-of-freedom torsional vibrator can be brought into a resonance state by applying an inherent periodic excitation force to the first frame. Then, by superimposing periodic excitation forces corresponding to the vibrations of the second frame and the third frame, the second frame and the third frame are vibrated at different frequencies and amplitudes, respectively. The light can be scanned two-dimensionally by reflecting the light on the reflecting surface.

JP 2008-129068 A

  However, the optical scanning device described in Patent Document 1 has a problem that when the environmental temperature changes, the resonance frequency of the three-degree-of-freedom torsional vibrator changes, and as a result, the scanning amplitude decreases as shown in FIG. It was. This uses a member that can be elastically deformed (hereinafter referred to as an elastic deformation member) as the rotation shaft in order to be able to twist and vibrate around the rotation shaft, and the elastic deformation member according to changes in the environmental temperature. This is due to the change in the spring constant.

  SUMMARY An advantage of some aspects of the invention is that it suppresses a change in scanning characteristics due to a temperature change in an optical scanning device using torsional vibration.

  The optical scanning device according to claim 1, which has been made to achieve the above object, has a reflecting portion having a reflecting surface for reflecting a light beam, and a first elasticity serving as a first rotating shaft for twisting and vibrating the reflecting portion. The optical scanning device includes a deformable member and scans the light beam reflected by the reflecting surface by swinging the reflecting portion about the first rotation axis.

  By the way, the resonance frequency f in the case where the reflecting portion is torsionally vibrated with the first elastic deformation member as the rotation axis is expressed by the following expression (1).

In Equation (1), k is the spring constant of the first elastic deformation member, and J is the moment of inertia of the reflecting portion.
And the spring constant k of a 1st elastic deformation member is represented by the following Formula (2).

  In Equation (2), β is a coefficient determined from the shape of the cross section of the first elastic deformation member. Further, a is the length of the long side of the cross section of the first elastic deformation member. Moreover, b is the length of the short side of the cross section of the first elastic deformation member. E is Young's modulus (lateral elastic modulus). Further, ν is a Poisson's ratio. L is the length of the first elastic deformation member. That is, when the Young's modulus E decreases, the spring constant k decreases.

  Further, the Young's modulus E is expressed by the following equation (3), where T is the temperature.

In Equation (3), E ₀ is the Young's modulus at 0 ° C. In addition, Δh _t is the temperature coefficient. That is, the Young's modulus E decreases as the temperature increases.
Therefore, when the Young's modulus E decreases with increasing temperature and the spring constant k of the first elastically deforming member decreases, the resonance frequency f decreases.

  On the other hand, in the optical scanning device according to claim 1, the connecting displacement portion connects the reflecting portion and the first elastic deformation member, and as the temperature increases, the moment of inertia around the first rotation axis of the reflecting portion increases. The reflecting part is displaced so as to be lowered.

  Therefore, by changing the moment of inertia around the first rotation axis of the reflecting portion in response to a decrease in Young's modulus associated with a temperature increase, it is possible to suppress a change in resonance frequency due to a temperature increase. Thereby, the change of the scanning characteristic by the temperature change can be suppressed.

  For example, as shown in FIG. 7, when the Young's modulus changes with temperature change, the resonance frequency changes (see curve L1 in FIG. 7). The amount of deviation from the specified resonance frequency at this time is represented by Δfa. On the other hand, under the condition that the Young's modulus is constant, the resonance frequency changes when the moment of inertia around the first rotation axis of the reflecting portion changes with temperature change (see curve L2 in FIG. 7). The amount of deviation from the specified resonance frequency at this time is Δfb.

  Accordingly, when the Young's modulus and the moment of inertia change simultaneously due to a temperature change, the deviation from the specified resonance frequency is | Δfa−Δfb |. For this reason, by designing | Δfa−Δfb | to be smaller than the allowable error Δε (refer to the curve L3 in FIG. 7), it is possible to suppress the change in the resonance frequency f accompanying the temperature rise.

  Further, in the optical scanning device according to claim 1, in order to change the moment of inertia around the first rotation axis of the reflecting portion, specifically, as described in claim 2, the reflecting surface of the reflecting portion is The connecting displacement portion may have a shape other than a circle and rotate the reflection portion around a displacement rotation axis that is a rotation axis perpendicular to the reflection surface as the displacement of the reflection portion.

  In the optical scanning device configured as described above, the reflection surface of the reflection portion has a shape other than a circle, and therefore, with the rotation of the reflection portion around the rotation axis (displacement rotation axis) perpendicular to the reflection surface. The distance between the point farthest from the first rotation axis and the first rotation axis in the reflecting portion changes. For example, in the case where the reflecting surface is elliptical, since the diameter is different between the major axis direction and the minor axis direction, the distance changes as the reflecting portion rotates. The moment of inertia can be changed by changing the distance.

  Further, in the optical scanning device according to claim 1, in order to change the moment of inertia around the first rotation axis of the reflecting portion, specifically, as described in claim 3, the connecting displacement portion has a reflecting As the displacement of the part, the reflecting part may be moved along a direction orthogonal to the first rotation axis.

  In the optical scanning device configured as described above, the distance between the reflection unit and the first rotation axis changes due to the movement of the reflection unit along the direction orthogonal to the first rotation axis. The moment of inertia can be changed by changing the distance.

  Further, in the optical scanning device according to any one of claims 1 to 3, as described in claim 4, the connection displacement portion includes at least two members made of materials having different coefficients of thermal expansion. It is good to be constructed by stacking.

  In the optical scanning device configured as described above, when the temperature is low, a member having a large coefficient of thermal expansion contracts greatly, so that the connecting displacement portion sandwiches the joint surface between two members having different coefficients of thermal expansion, It bends to the member side with a large coefficient of thermal expansion. On the other hand, when the temperature rises, the member having a large coefficient of thermal expansion expands greatly, and thus bends toward the member having a small coefficient of thermal expansion. Thereby, a reflection part can be automatically displaced to the position according to temperature.

  According to the optical scanning device configured as described above, the reflection unit can be displaced without using a temperature sensor that detects temperature and a control circuit that performs temperature correction based on the temperature detection result. The configuration of the apparatus can be simplified.

  Further, in the optical scanning device of the optical scanning device according to claim 4, as described in claim 5, the two members are a member made of silicon and an oxidation formed by thermally oxidizing silicon. A member made of silicon may be used.

The thermal expansion coefficients of silicon and silicon oxide are (2.6 × 10 ⁻⁶ ) and (0.5 × 10 ⁻⁶ ), respectively, and the thermal expansion coefficients are greatly different. Since a structure in which silicon and silicon oxide are laminated can be formed by thermally oxidizing a part of silicon, a process of bonding two separately formed members becomes unnecessary, and the manufacturing process Can be simplified.

  Further, in the optical scanning device according to claim 4 or 5, as described in claim 6, the connection displacement portion is configured by stacking two members made of materials having different coefficients of thermal expansion, Of the two members made of materials having different coefficients of thermal expansion, one member is formed in a shape in which a plurality of rod-shaped members are folded back so that the folded portion is U-shaped, and the other member is You may make it laminate | stack on one member formed in the folded shape so that a member and the other member may be arrange | positioned alternately.

  In the optical scanning apparatus configured as described above, one member (hereinafter referred to as a displacement first member) in the connection displacement portion is formed in a shape in which a plurality of rod-shaped members are folded back so that the folded portion is U-shaped. Has been. For this reason, when one end of the connecting displacement portion is connected to the reflection portion and the other end is connected to the first elastic deformation member, the displacement first member is compared with the case where the displacement first member is a linear member. The length of the member can be increased.

  The other member (hereinafter referred to as the displacement second member) is stacked on one member formed in a folded shape so that the displacement first member and the displacement second member are alternately arranged. The plurality of portions in which the displacement first member and the displacement second member are stacked are displaced in the same direction as the temperature changes. And as mentioned above, since the length of the displacement 1st member can be lengthened compared with the case where the displacement 1st member is a linear member, the displacement 1st member and the displacement 2nd member are The laminated part can be lengthened. That is, compared with the case where the displacement first member is a linear member, the portion to be displaced with the temperature change can be lengthened.

Therefore, according to the optical scanning device configured as described above, it is possible to increase the displacement of the reflecting portion as compared with the case where the displacement first member is a linear member.
Further, in the optical scanning device according to any one of claims 1 to 3, as described in claim 7, the connection displacement portion includes a substrate member made of the same material as the first elastic deformation member, A piezoelectric member formed by sandwiching a piezoelectric body between the first electrode and the second electrode is laminated, and a predetermined constant voltage is applied between the first electrode and the second electrode. You may make it apply always.

  In the optical scanning device configured as described above, the piezoelectric member is applied to the direction from the first electrode toward the second electrode by applying a constant voltage between the first electrode and the second electrode. Elongation or shrinkage occurs along a vertical surface (hereinafter referred to as an electrode facing surface).

  The piezoelectric constant d31, which is one of the physical property values of the piezoelectric body, is a value indicating the ease of expansion and contraction along the electrode facing surface when a voltage is applied to the piezoelectric body. It is known that the value of the constant d31 increases. That is, when the temperature changes, the value of the piezoelectric constant d31 changes, and the amount of expansion and contraction along the electrode facing surface of the piezoelectric body changes.

  For this reason, when the temperature rises, the piezoelectric member contracts along the electrode facing surface more than the substrate member, so that the connecting displacement portion formed by stacking the piezoelectric member and the substrate member is from the first electrode to the second electrode. Deflection in the direction of heading. That is, the length of the connecting displacement portion along the electrode facing surface becomes shorter as the temperature becomes higher. Thereby, a reflection part can be automatically displaced to the position according to temperature.

According to the optical scanning device thus configured, the configuration of the optical scanning device can be simplified as in the fourth aspect.
In addition, it is known that the amount of expansion and contraction along the electrode facing surface increases as the applied voltage value of the piezoelectric body increases.

  For this reason, the rigidity of the first elastic deformation member changes with the passage of time and the resonance frequency of the optical scanning device changes, or the rigidity of the piezoelectric member changes and the amount of expansion and contraction along the electrode facing surface changes. On the other hand, by adjusting the voltage value applied between the first electrode and the second electrode, the moment of inertia around the first rotation axis of the reflecting portion is changed to suppress the change in the resonance frequency accompanying the secular change. It becomes possible.

  Further, in the optical scanning device according to any one of claims 1 to 9, as described in claim 10, a first support portion that supports the first elastic deformation member, and a first support portion. A second elastic shaft having a second elastic deformation member connected to be elastically deformable, and having a second elastic deformation member as a second rotation shaft and swingably supporting the first support portion; May be arranged so as to intersect the first rotation axis.

  According to the optical scanning device configured as described above, the light beam reflected by the reflecting portion is scanned two-dimensionally by swinging about the first rotation axis and swinging about the second rotation axis. can do. Therefore, in the optical scanning device capable of two-dimensionally scanning the light beam, the same effect as that of the optical scanning device according to claim 1 can be obtained.

  Further, in the optical scanning device according to any one of claims 1 to 9, as described in claim 11, a first support portion that supports the first elastic deformation member, and a first support portion. A second support member having a second elastically deformable member connected thereto, the second support member supporting the first support member in a swingable manner with the second elastically deformable member as a second rotation shaft, and connected to the second support member; And a third support member that swingably supports the second support member with the third elastic member as a third rotating shaft, the second rotating shaft being The third rotation axis is arranged to intersect the first rotation axis and the second rotation axis, and the reflection unit, the first support unit, the second support unit, the second rotation unit, The three support portions, the first elastic deformation member, the elastic deformation member, and the third elastic deformation member are large when an inherent periodic external force is applied. A three-degree-of-freedom coupled vibration system that twists and vibrates at a rotation angle is configured, and a periodic external force acting on the three-degree-of-freedom coupled vibration system is applied to scan the light beam reflected by the reflecting surface. Also good.

  That is, the optical scanning device according to claim 11 has three degrees of freedom with respect to the first elastic deformation member, the second elastic deformation member, and the third elastic deformation member with the third support portion as a fixed end. It is a twisted vibrator.

  A three-degree-of-freedom torsional vibrator theoretically has three vibration modes. That is, the three vibration modes have different resonance frequencies, and the ratios of the angular amplitudes of the torsional vibrations of the reflection part, the first support part, and the second support part with respect to each resonance frequency are different (this is called a vibration mode). . Therefore, when the angular amplitude of the second support portion increases in a certain vibration mode, the angular amplitude of the reflection portion or the first support portion increases according to the ratio of the angular amplitude in the vibration mode.

Then, by applying a periodic external force inherent to the three-degree-of-freedom coupled vibration system, the three-degree-of-freedom torsional vibrator can be brought into a resonance state.
Further, if a periodic excitation force having a frequency corresponding to each of the three vibration modes is given, each vibration mode can be excited. In addition, if a plurality of periodic excitation forces with a plurality of frequencies are superimposed and applied, a plurality of vibration modes can be excited simultaneously.

  For this reason, by superimposing the periodic excitation force corresponding to the vibration mode with a large angular amplitude of the reflecting portion and the periodic excitation force corresponding to the vibration mode with a large angular amplitude of the first support portion, The light beam reflected by the reflecting portion can be scanned two-dimensionally.

  Therefore, according to the optical scanning device configured as described above, the same effect as the optical scanning device according to claim 1 can be obtained in the optical scanning device capable of two-dimensionally scanning the light beam.

1 is a plan view showing a configuration of an optical scanning device 1. FIG. 2 is a block diagram showing an electrical configuration of the optical scanning device 1. FIG. It is a figure which shows the change of the operation | movement according to the temperature in the thermal actuator. It is a figure which shows the change of the operation | movement according to the temperature in the light reflection part. 5 is a cross-sectional view showing a manufacturing process of the optical scanning device 1. FIG. 6 is a plan view showing a manufacturing process of the thermal actuator 33. FIG. It is a graph which shows the relationship between a Young's modulus and a moment of inertia, and a resonance frequency. It is a figure which shows the structure and operation | movement of the light reflection part 13 in 2nd, 3rd embodiment. It is a figure which shows the structure and operation | movement of the light reflection part 13 in 4th, 5th embodiment. It is a figure which shows the structure and operation | movement of the light reflection part 13 in 6th, 7th embodiment. 2 is a plan view showing a configuration of an optical scanning device 401. FIG. It is a figure which shows the structure and operation | movement of the light reflection part 413 in 8th Embodiment. It is sectional drawing which shows the structure of the rod-shaped members 511,512. It is a figure which shows the change of the operation | movement according to the temperature in the rod-shaped members 511,512. It is a figure which shows the change of the operation | movement according to the temperature in the thermal actuator. It is sectional drawing which shows the manufacturing process of the optical scanning device 401 in 8th Embodiment. It is a figure which shows the structure and operation | movement of the light reflection part 413 in 9th Embodiment. It is a figure which shows the change of the operation | movement according to the temperature in the thermal actuator. It is sectional drawing which shows the first half part of the manufacturing process of the optical scanning device 401 in 9th Embodiment. It is sectional drawing which shows the second half part of the manufacturing process of the optical scanning device 401 in 9th Embodiment. It is a figure which shows the structure and operation | movement of the light reflection part 413 of 10th Embodiment. It is a figure which shows the structure and operation | movement of the light reflection part 413 of 11th Embodiment. It is a figure which shows the structure of the light reflection part 413 of 12th Embodiment. It is a figure which shows operation | movement of the light reflection part 413 of 11th Embodiment. 2 is a plan view showing a configuration of an optical scanning device 201. FIG. 2 is a plan view showing a configuration of an optical scanning device 901. FIG. It is a graph which shows the relationship between the frequency and amplitude in an optical scanning device.

(First embodiment)
A first embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a plan view showing a configuration of an optical scanning device 1 according to an embodiment to which the present invention is applied.

  As shown in FIG. 1, the optical scanning device 1 applies a rotational driving force to a light beam scanning unit 2 that scans a light beam, a support unit 3 that supports the light beam scanning unit 2, and the light beam scanning unit 2. A drive unit 4 and an angle detection unit 5 that detects the rotation angle of the light beam scanning unit 2 are provided.

  The light beam scanning unit 2 includes an outer gimbal 11, an inner gimbal 12, a light reflecting unit 13, elastic connecting portions 14a and 14b, elastic connecting portions 15a and 15b, elastic connecting portions 16a and 16b, comb electrode portions 17 and 18, 19 and 20.

  Among these, the light reflecting portion 13 includes a mirror 31, a mirror support frame 32, and a thermal actuator 33. The mirror 31 has an elliptical shape, and a mirror surface portion of an aluminum thin film is formed on the surface. The mirror support frame 32 has a circular frame shape, and the mirror 31 is disposed in the frame. The thermal actuator 33 is formed by bonding two materials having different thermal expansion coefficients (details will be described later), and a plurality of thermal actuators 33 are arranged in the frame of the mirror support frame 32 to connect the mirror 31 and the mirror support frame 32. To do.

The inner gimbal 12 has a rectangular frame shape, and the light reflecting portion 13 is disposed in the frame. The outer gimbal 11 has a rectangular frame shape, and the inner gimbal 12 is arranged in the frame.
The elastic connecting portion 16 a is made of an elastically deformable material, and is disposed within the frame of the inner gimbal 12 to connect the light reflecting portion 13 and the inner gimbal 12. The elastic connecting portion 16b is made of an elastically deformable material, and is disposed within the frame of the inner gimbal 12, and on the side opposite to the elastic connecting portion 16a with the light reflecting portion 13 in between, The gimbal 12 is connected. The elastic connecting portion 16 a and the elastic connecting portion 16 b are arranged on the same straight line passing through the center of gravity JS of the light reflecting portion 13 and serve as the rotation axis k of the light reflecting portion 13. Thereby, the light reflection part 13 is comprised so that a torsional vibration is possible centering | focusing on the rotating shaft k.

  The elastic connecting portion 15 a is made of an elastically deformable material, and is disposed in the frame of the outer gimbal 11 to connect the inner gimbal 12 and the outer gimbal 11. The elastic connecting portion 15b is made of an elastically deformable material, and is arranged in the frame of the outer gimbal 11. The inner gimbal 12 and the outer gimbal 11 are disposed on the opposite side of the inner connecting gimbal 12 from the elastic connecting portion 15a. And The elastic connecting portion 15 a and the elastic connecting portion 15 b are arranged on the same straight line passing through the center of gravity JS of the light reflecting portion 13 and the inner gimbal 12 and serve as the rotation axis j of the light reflecting portion 13. Accordingly, the inner gimbal 12 is configured to be capable of torsional vibration about the rotation axis j.

  The elastic connecting portion 14 a is made of an elastically deformable material, and connects the upper side 11 a of the outer gimbal 11 and the support portion 3. The elastic connecting portion 14b is made of an elastically deformable material, and connects the lower side 11b of the outer gimbal 11 and the support portion 3 on the opposite side of the elastic connecting portion 14a across the outer gimbal 11. The elastic connecting portion 14 a and the elastic connecting portion 14 b are arranged on the same straight line passing through the center of gravity JS of the light reflecting portion 13, the inner gimbal 12, and the outer gimbal 11, and serve as the rotation axis i of the outer gimbal 11. Accordingly, the outer gimbal 11 is configured to be able to twist and vibrate about the rotation axis i.

  The comb electrode portion 17 is formed in a comb shape along the left side 11 c of the outer gimbal 11. Further, the comb electrode portion 18 is formed in a comb shape along the left side 11 c above the comb electrode portion 17.

  Further, the comb electrode portion 19 is formed in a comb shape along the right side 11 d of the outer gimbal 11. Further, the comb electrode portion 20 is formed in a comb shape along the right side 11 d above the comb electrode portion 17.

  Next, the support portion 3 includes an upper support portion 3a connected to an end portion of the elastic connection portion 14a on the side not connected to the upper side 11a, and an end portion of the elastic connection portion 14b on the side not connected to the lower side 11b. It is comprised from the lower side support part 3b connected.

  Further, the driving unit 4 is formed in a comb-teeth electrode portion 4a formed in a comb-teeth shape that meshes with the comb-teeth electrode unit 17 with a predetermined interval, and in a comb-teeth shape that meshes with the comb-teeth electrode unit 19 with a predetermined interval. And the comb electrode portion 4b.

  Further, the angle detection unit 5 is formed in a comb-teeth shape that is meshed with the comb-teeth electrode unit 18 with a predetermined interval and a comb-teeth shape that is meshed with the comb-teeth electrode unit 20 with a predetermined interval. It is comprised from the comb-tooth electrode part 5b made.

Next, the electrical configuration of the optical scanning device 1 will be described. FIG. 2 is a block diagram showing an electrical configuration of the optical scanning device 1.
As shown in FIG. 2, the optical scanning device 1 includes a drive signal generation circuit 41 that outputs a pulse voltage as a drive signal for rotationally driving the light beam scanning unit 2, and the drive output by the drive signal generation circuit 41. An amplifier circuit 42 that amplifies the signal and applies it to the comb electrode portions 4a and 4b, and C− that converts the capacitance between the comb electrode portions 5a and 5b and the comb electrode portions 18 and 20 into a voltage value. From the V conversion circuits 43a and 43b (hereinafter, the CV conversion circuits 43a and 43b are collectively referred to as the CV conversion circuit 43), the semiconductor laser 44 serving as a light beam emission source, and the CV conversion circuit 43. A control circuit 45 that monitors the output voltage, controls the semiconductor laser 44 based on the voltage value, and controls the drive signal generation circuit 41 is provided.

Next, the operation principle of the optical scanning device 1 will be described.
The optical scanning device 1 is a three-degree-of-freedom torsional vibrator having a degree of freedom of twisting with respect to the rotation axes i, j, and k with the support portion 3 as a fixed end.

  A three-degree-of-freedom torsional vibrator theoretically has three vibration modes. That is, the three vibration modes have different resonance frequencies, and the ratio of the angular amplitude of the torsional vibration of each frame to each resonance frequency is different (this is called a vibration mode). Hereinafter, these three vibration modes are referred to as vibration mode 1, vibration mode 2, and vibration mode 3, respectively.

  When a voltage is applied to the comb electrode portions 4a and 4b, an electrostatic force is generated between the comb electrode portions 17 and 19. Further, while the outer gimbal 11 vibrates for one cycle, the comb electrode portions 17 and 19 come closest to the comb electrode portions 4a and 4b twice. For this reason, if a periodic electrostatic force close to twice the resonance frequency is applied, the three-degree-of-freedom torsional vibrator can be brought into a resonance state (hereinafter, an excitation force for making the resonance state is referred to as a periodic excitation force). Further, every time the comb electrode portions 17 and 19 approach the comb electrode portions 4a and 4b, a periodic excitation force can be applied.

  If a periodic excitation force having a frequency corresponding to each of vibration mode 1, vibration mode 2, and vibration mode 3 is applied, the respective vibration modes can be excited. In addition, if a plurality of periodic excitation forces with a plurality of frequencies are superimposed and applied, a plurality of vibration modes can be excited simultaneously.

Here, for example,
The resonance frequency f1 of vibration mode 1 is 1000 Hz,
The resonance frequency f2 of vibration mode 2 is 5000 Hz,
The resonance frequency f3 of vibration mode 3 is 40000 Hz,
The amplitude ratio r1 of the outer gimbal 11, the inner gimbal 12, and the light reflecting portion 13 in the vibration mode 1 is “1: −20: 0.5”,
The amplitude ratio r2 of the outer gimbal 11, the inner gimbal 12, and the light reflecting portion 13 in the vibration mode 2 is set to “1: 0.5: −0.1”,
The amplitude ratio r3 of the outer gimbal 11, the inner gimbal 12, and the light reflecting portion 13 in the vibration mode 3 is “1: 0.01: −30”,
The operation of the three-degree-of-freedom torsional vibrator will be described.

  The amplitude ratio in each vibration mode is described in the order of the outer gimbal 11, the inner gimbal 12, and the light reflecting portion 13 from the left. For example, when the amplitude of the outer gimbal 11 is “1”, the amplitude ratio r1 indicates that the amplitude of the inner gimbal 12 is “−20” and the amplitude of the light reflecting portion 13 is “0.5”.

  In the resonance state of the three-degree-of-freedom torsional vibrator, the phase angle between the frames is theoretically 0 degree or 180 degrees. Therefore, when describing the amplitude ratio, the sign is “+” when the phase angle difference is 0 degree, and the sign is “−” when the difference is 180 degrees. For example, the amplitude ratio r1 indicates that the phase angle difference between the outer gimbal 11 and the light reflecting portion 13 is 0 degree, and the phase angle difference between the outer gimbal 11 and the inner gimbal 12 is 180 degrees.

  When the resonance frequency and amplitude ratio of each vibration mode are designed as described above, in the vibration mode 1, the inner gimbal 12 and the light reflecting portion 13 connected to the inner gimbal 12 are largely torsionally vibrated at 1000 Hz. Moreover, in the vibration mode 3, the light reflection part 13 mainly torsionally vibrates at 40000 Hz.

  For this reason, the laser beam is reflected by the mirror surface portion of the light reflecting portion 13 and the vibration mode 1 and the vibration mode 3 are simultaneously excited, so that the vibration mode 3 is in the main scanning direction (40000 Hz) and the vibration mode 1 is sub-scanned. Laser light can be scanned two-dimensionally in the direction (1000 Hz).

Next, the operation of the optical scanning device 1 will be described.
When the drive signal generation circuit 41 outputs a drive signal based on the control by the control circuit 45, the voltage value of the drive signal is amplified by the amplifier circuit 42 and applied to the comb electrode portions 4a and 4b. Thereby, a pulse voltage is applied between the comb-tooth electrode portions 4a and 4b and the comb-tooth electrode portions 17 and 19 to generate an electrostatic attractive force that periodically changes, and the elastic coupling portions 14a and 14b are elastically deformed. By twisting, the light beam scanning unit 2 reciprocally vibrates about the elastic coupling portions 14a and 14b as the rotation axis i.

  Here, the drive signal generation circuit 41 outputs a drive signal having a frequency twice the resonance frequency of the vibration mode in which the angular amplitude of the light reflecting portion 13 is larger than that of the outer gimbal 11 and the inner gimbal 12. As a result, the vibration system including the light beam scanning unit 2 and the elastic coupling portions 14a and 14b resonates, and the light beam scanning unit 2 reciprocally vibrates at the resonance frequency.

  In this state, when the light reflecting portion 13 is irradiated with a light beam from the semiconductor laser 44, the light beam is emitted by being reflected by the mirror surface of the light reflecting portion 13, and the light reflecting portion 13 is reciprocated. Accordingly, scanning is performed in a direction corresponding to the rotation angle of the light reflecting portion 13.

  On the other hand, with the reciprocal vibration of the outer gimbal 11, the distance between the comb electrode portions 5a and 5b and the comb electrode portions 18 and 20 also periodically changes. As a result, the capacitance between the comb electrode portions 5 a and 5 b and the comb electrode portions 18 and 20 changes according to the rotation angle of the outer gimbal 11. The control circuit 45 detects the rotation angle of the outer gimbal 11 based on these capacitances. As described above, since the amplitude ratio is theoretically maintained in the resonance state of the three-degree-of-freedom torsional vibrator, the rotation angle of the light reflecting portion 13 is detected by detecting the rotation angle of the outer gimbal 11. can do.

  Next, the configuration and operation of the thermal actuator 33 and the light reflecting portion 13 will be described. FIG. 3 is a diagram illustrating a change in operation of the thermal actuator 33 according to the temperature. FIG. 4 is a diagram illustrating a change in operation according to the temperature in the light reflecting section 13.

  As shown in FIG. 3A, the thermal actuator 33 includes a rod-shaped member 51 formed in a rod shape using silicon as a material and a rod-shaped member 52 formed in a rod shape using silicon oxide as a material, which are orthogonal to the longitudinal direction. Are stacked along the direction (hereinafter referred to as the stacking direction D1). Further, the thermal actuator 33 is formed such that the rod-shaped member 51 and the rod-shaped member 52 extend linearly under the condition that the temperature is room temperature.

The thermal expansion coefficients of silicon and silicon oxide are (2.6 × 10 ⁻⁶ ) and (0.5 × 10 ⁻⁶ ), respectively. For this reason, under the condition where the temperature is lower than room temperature, as shown in FIG. 3B, silicon contracts more than silicon oxide (see arrow D2). Thereby, when the temperature becomes lower than room temperature, the thermal actuator 33 bends toward the rod-shaped member 51 (silicon) side with the joint surface between the rod-shaped member 51 and the rod-shaped member 52 interposed therebetween.

  On the other hand, under a situation where the temperature is higher than room temperature, as shown in FIG. 3C, silicon expands more than silicon oxide (see arrow D3). Thereby, when the temperature becomes higher than room temperature, the thermal actuator 33 bends toward the rod-shaped member 52 (silicon oxide) side with the joint surface between the rod-shaped member 51 and the second rod-shaped member 52 interposed therebetween.

  As shown in FIG. 4A, each of the plurality of thermal actuators 33 is disposed between the mirror 31 and the mirror support frame 32, one end of which is connected to the inner peripheral portion of the mirror support frame 32 and the other. The end is connected to the outer periphery of the mirror 31. Thereby, the mirror 31 and the mirror support frame 32 are connected so as to be movable integrally.

  Further, the plurality of thermal actuators 33 are installed so that the bar-shaped members 51 and the bar-shaped members 52 are alternately arranged along the circumferential direction of the mirror 31. As described above, the thermal actuator 33 bends toward the rod-shaped member 51 (silicon) when the temperature is lower than room temperature, and bends toward the rod-shaped member 52 (silicon oxide) when the temperature is higher than room temperature.

Therefore, the connection ends of the plurality of thermal actuators 33 with the mirror 31 are displaced in the same direction along the circumferential direction of the mirror 31 according to a temperature change.
For example, as shown in FIG. 4A, in each thermal actuator 33, when the rod-like member 52 is arranged on the counterclockwise direction side with the joint surface between the rod-like member 51 and the rod-like member 52 interposed therebetween, the temperature 4 becomes higher than room temperature, the connection end with the mirror 31 is displaced counterclockwise along the circumferential direction of the mirror 31 as shown in FIG. 4B (see arrow D4). This is because when the temperature is higher than room temperature, the rod-shaped member 52 is bent. Thereby, the mirror 31 rotates counterclockwise around the rotation axis m orthogonal to the mirror surface of the mirror 31 (see arrow D5). On the other hand, when the temperature becomes lower than room temperature, the mirror 31 rotates clockwise around the rotation axis m.

  Furthermore, the mirror 31 is elliptical. For this reason, the smaller the angle θ formed between the major axis L of the mirror 31 and the rotation axis k, the smaller the moment of inertia around the rotation axis k. Therefore, by setting the position of the mirror 31 so that the angle θ becomes smaller as the temperature becomes higher, the moment of inertia around the rotation axis k becomes smaller as the temperature becomes higher.

  Next, a method for manufacturing the optical scanning device 1 will be described with reference to FIGS. FIG. 5 is a cross-sectional view showing a manufacturing process of the optical scanning device 1. FIG. 6 is a plan view showing a manufacturing process of the thermal actuator 33.

  As shown in FIG. 5A, the optical scanning device 1 is manufactured, for example, by processing an SOI (Silicon On Insulator) substrate 300 by a semiconductor process. The SOI substrate 300 has a structure in which a buried oxide film layer 320 and a single crystal silicon layer 330 are sequentially stacked on a silicon substrate 310. Hereinafter, the silicon substrate 310 is referred to as a handle layer 310, and the single crystal silicon layer 330 is referred to as a device layer 330.

  First, in order to manufacture the thermal actuator 33, as shown in FIG. 5B, a DRIE (Deep Reactive Ion) is formed in a region 331 (hereinafter referred to as a thermal actuator arrangement region 331) in the device layer 330 where the thermal actuator 33 is arranged. After the trench 332 is formed by etching, thermal oxidation treatment is performed over the entire surface of the device layer 330. As a result, the thermal oxide film 340 is formed on the surface of the device layer 330 and the thermal oxide film 340 is also formed on the sidewalls of the trench 332. A thermal oxide film 350 is also formed on the back surface of the handle layer 310.

  Specifically, as shown in FIG. 6A, first, in the thermal actuator arrangement region 331 of the device layer 330, the portion where the rod-shaped member 52 made of silicon oxide is formed is patterned in a comb shape, A trench 332 is formed by DRIE in the depth direction of the drawing.

  Then, by performing a thermal oxidation process, a thermal oxide film 340 is formed on the sidewall of the trench 332 as shown in FIG. Due to the oxidation reaction of silicon, the volume of the trench side wall portion is increased, the width of the trench 332 is narrowed, and the width of the comb-like projection 333 is also narrowed. After FIG. 6B, the illustration of the thermal oxide film 340 formed on the device layer 330 is actually omitted as shown in FIG. 5B.

  Thereafter, when the thermal oxidation treatment is further performed, the width of the trench 332 is further reduced, the thermal oxide films grown from both side surfaces of the trench are brought into close contact with each other, and all the comb-like projections 333 are also thermally oxidized. c) and as shown in FIG. 6 (c).

  As will be described later, the device layer 330 in the device layer etching region 342 is etched by DRIE (see FIG. 6D), and then a recess 370 is formed in the handle layer 310, and the buried oxide film 320 is formed. By removing, the thermal actuator 33 is formed (see FIG. 6E).

Thereafter, an aluminum thin film is deposited on the thermal oxide film 340 and patterned to form a mirror surface portion 345 of the mirror 31 as shown in FIG.
Further, as shown in FIG. 5E, the thermal oxide film 340 in the electrode formation region 341 and the device layer etching region 342 is etched. Thereafter, as shown in FIG. 5 (f), an aluminum thin film is deposited on the device layer 330 in the electrode formation region 341 and patterned to form an aluminum electrode 360, and as shown in FIG. 5 (g). Then, the device layer 330 in the device layer etching region 342 is etched by DRIE.

  Thereafter, as shown in FIG. 5 (h), the region corresponding to the light beam scanning portion 2 in the thermal oxide film 350 on the back surface of the handle layer 310 is removed by etching, and further, as shown in FIG. 5 (i). By etching the handle layer 310 using the thermal oxide film 350 that has not been removed as a mask, the recess 370 is formed in the handle layer 310.

  Further, as shown in FIG. 5J, the region of the recess 370 in the buried oxide film layer 320 is removed by etching, and further, as shown in FIG. 5K, the thermal oxide film 350 on the back surface of the silicon substrate 310 is removed. Are removed by etching. Accordingly, the optical scanning device 1 is configured such that the light beam scanning unit 2 can rotate.

  The optical scanning device 1 configured as described above includes a mirror 31 having a reflecting surface that reflects a light beam, and elastic coupling portions 16a and 16b serving as a rotation axis k for torsionally vibrating the mirror 31, and the rotation axis. The light beam reflected by the reflecting surface is scanned by swinging the mirror 31 around k.

  By the way, the resonance frequency f when the mirror 31 is torsionally oscillated with the elastic coupling portions 16a and 16b as the rotation axes is expressed by the following expression (1).

In equation (1), k is the spring constant of the elastic coupling portions 16 a and 16 b, and J is the moment of inertia of the mirror 31.
And the spring constant k of the elastic connection parts 16a and 16b is represented by the following formula (2).

  In equation (2), β is a coefficient determined from the cross-sectional shape of the elastic coupling portions 16a and 16b. Moreover, a is the length of the long side of the cross section of the elastic connection parts 16a and 16b. Moreover, b is the length of the short side of the cross section of the elastic connection parts 16a and 16b. E is Young's modulus (lateral elastic modulus). Further, ν is a Poisson's ratio. In addition, l is the length of the elastic connecting portions 16a and 16b. That is, when the Young's modulus E decreases, the spring constant k decreases.

  Further, the Young's modulus E is expressed by the following equation (3), where T is the temperature.

In Equation (3), E ₀ is the Young's modulus at 0 ° C. In addition, Δh _t is the temperature coefficient. That is, the Young's modulus E decreases as the temperature increases.
Therefore, when the Young's modulus E decreases as the temperature increases and the spring constant k of the elastic coupling portions 16a and 16b decreases, the resonance frequency f decreases.

  On the other hand, in the optical scanning device 1, the mirror support frame 32 and the thermal actuator 33 connect the mirror 31 and the elastic connecting portions 16a and 16b, and as the temperature increases, the moment of inertia around the rotation axis k of the mirror 31 increases. The mirror 31 is displaced so as to be lowered.

  Accordingly, by reducing the moment of inertia around the rotation axis k of the mirror 31 in response to a decrease in Young's modulus E accompanying a temperature rise, it is possible to suppress a change in the resonance frequency f accompanying a temperature rise. Thereby, the change of the scanning characteristic by the temperature change can be suppressed.

  For example, as shown in FIG. 7, when the Young's modulus changes with temperature change, the resonance frequency changes (see curve L1 in FIG. 7). The amount of deviation from the specified resonance frequency at this time is represented by Δfa. On the other hand, when the moment of inertia around the rotation axis k of the mirror 31 changes with temperature change under the condition that the Young's modulus is constant, the resonance frequency changes (see curve L2 in FIG. 7). The amount of deviation from the specified resonance frequency at this time is Δfb.

  Accordingly, when the Young's modulus and the moment of inertia change simultaneously due to a temperature change, the deviation from the specified resonance frequency is | Δfa−Δfb |. For this reason, by designing | Δfa−Δfb | to be smaller than the allowable error Δε (refer to the curve L3 in FIG. 7), it is possible to suppress the change in the resonance frequency f accompanying the temperature rise.

  In order to change the moment of inertia around the rotation axis k of the mirror 31, the reflecting surface of the mirror 31 has a shape other than a circle (in this embodiment, an elliptical shape), and the thermal actuator 33 is perpendicular to the reflecting surface. The mirror 31 is rotated around the rotation axis m.

  That is, since the reflecting surface of the mirror 31 has a shape other than a circle, the mirror 31 rotates at a point farthest from the rotation axis k with the rotation of the mirror 31 about the rotation axis m perpendicular to the reflecting surface. The distance from the axis k changes. In this embodiment, since the reflecting surface of the mirror 31 is elliptical, the major axis direction and the minor axis direction have different diameters, and the distance changes as the mirror 31 rotates. The moment of inertia can be changed by changing the distance.

  The thermal actuator 33 is formed by laminating a rod-shaped member 51 (silicon) and a rod-shaped member 52 (silicon oxide) made of materials having different thermal expansion coefficients. Therefore, when the temperature is lowered, the rod-shaped member 51 having a large coefficient of thermal expansion contracts greatly, so that the thermal actuator 33 sandwiches the joint surface between the rod-shaped member 51 and the rod-shaped member 52 and the rod-shaped member 51 having a large coefficient of thermal expansion. Bend to the side. On the other hand, when the temperature is increased, the rod-shaped member 51 having a large coefficient of thermal expansion is greatly expanded, and is bent toward the rod-shaped member 52 having a small coefficient of thermal expansion. Thereby, a reflection part can be automatically displaced to the position according to temperature.

  Accordingly, the reflection unit can be displaced without using a temperature sensor for detecting temperature and a control circuit for performing temperature correction based on the temperature detection result, so that the configuration of the optical scanning device 1 can be simplified. it can.

The rod-shaped members 51 and 52 made of materials having different coefficients of thermal expansion are a member made of silicon and a member made of silicon oxide formed by thermally oxidizing silicon. The thermal expansion coefficients of silicon and silicon oxide are (2.6 × 10 ⁻⁶ ) and (0.5 × 10 ⁻⁶ ), respectively, and the thermal expansion coefficients are greatly different. Since a structure in which silicon and silicon oxide are laminated can be formed by thermally oxidizing a part of silicon, a process of bonding two separately formed members becomes unnecessary, and the manufacturing process Can be simplified.

  In the embodiment described above, the mirror 31 is the reflection portion in the present invention, the rotation axis k is the first rotation shaft in the present invention, and the elastic coupling portions 16a and 16b are the first elastic deformation member, the mirror support frame 32 in the present invention and the heat. The actuator 33 is a connecting displacement portion in the present invention, the rotation axis m is a displacement rotation shaft in the present invention, and the rod-shaped members 51 and 52 are two members made of materials having different coefficients of thermal expansion in the present invention.

  Further, the inner gimbal 12 is the first support portion in the present invention, the elastic connecting portions 15a and 15b are the second elastic deformation members in the present invention, the rotation axis j is the second rotation shaft in the present invention, and the outer gimbal 11 is the first in the present invention. 2 is a third elastic deformation member in the present invention, the rotation shaft i is a third rotation shaft in the present invention, and the support portion 3 is a third support portion in the present invention.

(Second Embodiment)
A second embodiment of the present invention will be described below with reference to the drawings. In the second embodiment, only parts different from the first embodiment will be described.

  The optical scanning device 1 in the second embodiment is the same as that in the first embodiment except that the configuration of the light reflecting unit 13 is changed. FIG. 8A is a diagram showing the configuration and operation of the light reflecting section 13 in the second embodiment.

The light reflecting portion 13 of the second embodiment is the same as that of the first embodiment except that a thermal actuator 60 is provided instead of the thermal actuator 33 as shown in FIG.
The thermal actuator 60 includes a folded member 61 formed in a shape in which a rod-shaped member is folded back evenly using silicon as a material, and a rod-shaped member 62 formed in a rod shape using silicon oxide as a material.

  The folding member 61 includes a radial member 66 extending in the direction from the mirror 31 to the mirror support frame 32 or the direction from the mirror support frame 32 to the mirror 31 (that is, the radial direction of the circular mirror support frame 32), and the mirror 31. And circumferential members 67 extending along the circumferential direction are alternately connected to each other. The folding member 61 has one end 61 a connected to the inner peripheral portion of the mirror support frame 32 and the other end 61 b connected to the outer peripheral portion of the mirror 31.

  The radial members 66 and the rod-shaped members 62 are alternately arranged along the radial direction of the circular mirror support frame 32 with respect to each of the plurality of radial members 66 constituting the folding member 61. The rod-shaped member 62 is laminated. Accordingly, the plurality of radial members 66 constituting the folding member 61 are displaced in the same direction along the circumferential direction of the mirror 31 according to the temperature change (see arrow D11).

  Further, the plurality of thermal actuators 60 are installed such that the radial members 66 and the rod-shaped members 62 are alternately arranged with respect to the adjacent thermal actuators 60. Therefore, in the plurality of thermal actuators 60, the connection end with the mirror 31 is displaced in the same direction along the circumference of the mirror 31 according to the temperature change (see arrow D12).

  In the optical scanning device 1 configured as described above, the thermal actuator 60 is configured by stacking the folding member 61 and the rod-shaped member 62 made of materials having different coefficients of thermal expansion, and the folding member 61 has a U-shaped folded portion. The bar-shaped member 62 is formed in a shape that is folded back in a plurality of shapes, and the bar-shaped member 62 is a folded member 61 that is formed in a folded shape so that the folded members 61 and the bar-shaped members 62 are alternately arranged. Is laminated. For this reason, when one end of the thermal actuator 60 is connected to the mirror 31 and the other end is connected to the mirror support frame 32, the length of the folding member 61 is increased compared to the case of a linear member. Can do.

  And since the rod-shaped member 62 is laminated | stacked on the folding member 61 formed in the folded shape so that the folding member 61 and the rod-shaped member 62 may be arrange | positioned alternately, the folding member 61 and the rod-shaped member 62 are laminated | stacked. The plurality of portions displaced in the same direction as the temperature changes. And as above-mentioned, since the folding member 61 can lengthen the length of the folding member 61 compared with the case where it is a linear member, the folding member 61 and the rod-shaped member 62 were laminated | stacked. The part can be lengthened. That is, compared with the case where it is a linear member, the part displaced with a temperature change can be lengthened. Therefore, it is possible to increase the displacement of the mirror 31 as compared with the case where the folding member 61 is a linear member.

For this reason, even when the difference in coefficient of thermal expansion between the folding member 61 and the rod-shaped member 62 is small, the amount of rotation of the mirror 31 can be increased.
Furthermore, since the amount of rotation can be increased, the moment of inertia around the rotation axis k of the mirror 31 can be greatly changed even when the major axis of the elliptical mirror 31 is small. Thereby, the mirror 31 can be made small.

In the embodiment described above, the folding member 61 is one member in the present invention, and the rod-shaped member 62 is the other member in the present invention.
(Third embodiment)
A third embodiment of the present invention will be described below with reference to the drawings. In the third embodiment, only parts different from the first embodiment will be described.

  The optical scanning device 1 in the third embodiment is the same as that in the first embodiment except that the configuration of the light reflecting section 13 is changed. FIG. 8B is a diagram illustrating the configuration and operation of the light reflecting section 13 in the third embodiment.

  The light reflecting portion 13 of the third embodiment is the same as that of the first embodiment except that a thermal actuator 70 is provided instead of the mirror support frame 32 and the thermal actuator 33 as shown in FIG. .

  The thermal actuator 70 includes a plurality of (two in this embodiment) folded members 71 formed in a shape in which a rod-shaped member is folded using silicon as a material, and a rod-shaped member 72 formed in a rod shape using silicon oxide as a material. Has been.

  The folding member 71 includes a circumferential member 76 extending along the circumference of the mirror 31 and a direction from the mirror 31 toward the circumferential member 76 or a direction from the circumferential member 76 toward the mirror 31 (that is, the elliptical mirror 31). The radial members 77 extending in the radial direction are alternately connected to each other.

  At least one of the plurality of folding members 71 has one end 71a connected to the elastic coupling portion 16a and the other end 71b connected to the outer peripheral portion of the mirror 31, while at least one of the one end 71a. Is connected to the elastic connecting portion 16 b and the other end 71 b is connected to the outer peripheral portion of the mirror 31.

  Then, the rod-shaped members 72 are laminated so that the circumferential members 76 and the rod-shaped members 72 are alternately arranged along the radial direction of the mirror 31 with respect to the circumferential member 76 constituting the folding member 71. Therefore, the folding member 71 is displaced along the radial direction of the mirror 31 according to the temperature change (see the arrow D21). Further, the two folding members 71 constituting the thermal actuator 70 are arranged so as to be point-symmetric about the rotation axis m of the mirror 31. Thereby, the connection end with the mirror 31 of the two thermal actuators 70 is displaced in the same direction along the circumference of the mirror 31 according to the temperature change (see arrow D22).

  In the optical scanning device 1 configured as described above, the mirror 31 and the elastic coupling portions 16a and 16b are coupled by the thermal actuator 70 without using the mirror support frame 32, and the rotation axis of the mirror 31 increases as the temperature increases. The mirror 31 can be displaced so that the moment of inertia around k is low.

  In the embodiment described above, the thermal actuator 70 is the connecting displacement portion in the present invention, the folding member 71 is one member in the present invention, and the rod-shaped member 72 is the other member in the present invention.

(Fourth embodiment)
Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings. In the fourth embodiment, only parts different from the first embodiment will be described.

  The optical scanning device 1 in the fourth embodiment is the same as that in the first embodiment except that the configuration of the light reflecting unit 13 is changed. FIG. 9A is a diagram illustrating the configuration and operation of the light reflecting section 13 in the fourth embodiment.

  The light reflecting portion 13 of the fourth embodiment is the same as that of the first embodiment except that a thermal actuator 80 is provided instead of the mirror support frame 32 and the thermal actuator 33 as shown in FIG. .

  The thermal actuator 80 includes a plurality of (two in this embodiment) folded members 81 formed in a shape in which a rod-shaped member is folded using silicon as a material, and a rod-shaped member 82 formed in a rod shape using silicon oxide as a material. Has been.

  The folding member 81 is formed by alternately connecting a short-axis direction member 86 extending along the short-axis direction of the elliptical mirror 31 and a long-axis direction member 87 extending along the long-axis direction of the mirror 31. Yes. The mirror 31 is arranged so that its long axis is orthogonal to the rotation axis k.

  In addition, at least one of the plurality of folding members 81 has one end 81a connected to the elastic coupling portion 16a and the other end 81b connected to the outer peripheral portion of the mirror 31, while at least one has one end 81a. Is connected to the elastic coupling portion 16 b and the other end 81 b is connected to the outer peripheral portion of the mirror 31.

  Then, the rod-shaped members 82 are laminated so that the short-axis direction members 86 and the rod-shaped members 82 are alternately arranged along the long-axis direction of the mirror 31 with respect to the short-axis direction members 86 constituting the folding member 81. The Accordingly, the folding member 81 is displaced along the major axis direction of the mirror 31 according to the temperature change (see arrow D31). Further, the two folding members 81 constituting the thermal actuator 80 are arranged so as to be line symmetrical about the major axis of the mirror 31. Thereby, the connection end with the mirror 31 of the two thermal actuators 80 is displaced in the same direction along the major axis direction of the mirror 31 according to the temperature change (see arrow D32).

  The inertia around the rotation axis k becomes shorter as the distance (see the distance I31) between the point (see the point P31) farthest from the rotation axis k and the rotation axis k in the peripheral portion of the elliptical mirror 31 becomes shorter. The moment becomes smaller. Therefore, by connecting the thermal actuator 80 and the mirror 31 so that the distance becomes smaller as the temperature becomes higher, the moment of inertia around the rotation axis k becomes smaller as the temperature becomes higher.

  In the optical scanning device 1 configured as described above, the thermal actuator 80 moves the mirror 31 along the direction orthogonal to the rotation axis k, thereby changing the distance between the mirror 31 and the rotation axis k. The moment of inertia can be changed by changing the distance.

  In the embodiment described above, the thermal actuator 80 is the connecting displacement portion in the present invention, the folding member 81 is one member in the present invention, and the rod-shaped member 82 is the other member in the present invention.

(Fifth embodiment)
A fifth embodiment of the present invention will be described below with reference to the drawings. In the fifth embodiment, only parts different from the first embodiment will be described.

  The optical scanning device 1 in the fifth embodiment is the same as that in the first embodiment except that the configuration of the light reflecting unit 13 is changed. FIG. 9B is a diagram illustrating the configuration and operation of the light reflecting section 13 in the fifth embodiment.

The light reflecting portion 13 of the fifth embodiment is the same as that of the first embodiment except that a thermal actuator 90 is provided instead of the thermal actuator 33 as shown in FIG.
The thermal actuator 90 is configured by laminating a rod-shaped member 91 formed in a rod shape using silicon as a material and a rod-shaped member 92 formed in a rod shape using silicon oxide as a material along a direction orthogonal to the longitudinal direction. ing.

  Each of the plurality of thermal actuators 90 is disposed between the mirror 31 and the mirror support frame 32, and one end thereof is connected to the inner peripheral part of the mirror support frame 32 and the other end is connected to the outer peripheral part of the mirror 31. Is done.

  Further, the plurality of thermal actuators 90 are installed so that the bar-shaped members 91 and the bar-shaped members 92 are alternately arranged along the major axis direction of the mirror 31. As described above, the thermal actuator 33 bends toward the rod-shaped member 91 (silicon) when the temperature is lower than room temperature, and bends toward the rod-shaped member 92 (silicon oxide) when the temperature is higher than room temperature. Therefore, in the plurality of thermal actuators 90, the connection end with the mirror 31 is displaced in the same direction along the major axis direction of the mirror 31 according to the temperature change (see arrow D41). Further, the two rod-shaped members 91 constituting the thermal actuator 90 are arranged so as to be line symmetric with respect to the major axis of the mirror 31. Accordingly, the plurality of thermal actuators 90 are displaced in the same direction along the major axis direction of the mirror 31 in accordance with the temperature change (see arrow D42).

  The inertia around the rotation axis k becomes shorter as the distance (see the distance I41) between the point (see the point P41) farthest from the rotation axis k and the rotation axis k in the peripheral edge of the elliptical mirror 31 becomes shorter. The moment becomes smaller. Therefore, by connecting the thermal actuator 90 and the mirror 31 so that the above distance becomes smaller as the temperature becomes higher, the moment of inertia around the rotation axis k becomes smaller as the temperature becomes higher.

  In the optical scanning device 1 configured as described above, the thermal actuator 90 moves the mirror 31 along the direction orthogonal to the rotation axis k, thereby changing the distance between the mirror 31 and the rotation axis k. The moment of inertia can be changed by changing the distance.

  In the embodiment described above, the mirror support frame 32 and the thermal actuator 90 are the connecting displacement portions in the present invention, and the rod-shaped members 91 and 92 are two members made of materials having different coefficients of thermal expansion in the present invention.

(Sixth embodiment)
A sixth embodiment of the present invention will be described below with reference to the drawings. In the sixth embodiment, only parts different from the first embodiment will be described.

  The optical scanning device 1 in the sixth embodiment is the same as that in the first embodiment except that the configuration of the light reflecting unit 13 is changed. FIG. 10A is a diagram illustrating the configuration and operation of the light reflecting section 13 in the sixth embodiment.

  As shown in FIG. 10A, the light reflecting portion 13 of the sixth embodiment has a point that the mirror 31 is circular instead of elliptical, and the thermal actuator 100 is replaced by the mirror support frame 32 and the thermal actuator 33. Except for the points provided, the second embodiment is the same as the first embodiment.

  The thermal actuator 100 includes a plurality of (two in this embodiment) folded members 101 formed in a shape in which a rod-shaped member is folded using silicon as a material, and a rod-shaped member 102 formed in a rod shape using silicon oxide as a material. Has been.

  The folding member 101 includes a mirror direction member 106 extending along a direction parallel to the mirror surface of the mirror 31 (hereinafter referred to as a mirror surface direction) and a direction orthogonal to the mirror surface of the mirror 31 (hereinafter referred to as a mirror surface orthogonal direction). Mirror surface orthogonal direction members 107 extending along the line are alternately connected to each other.

  At least one of the plurality of folding members 101 has one end 101a connected to the elastic coupling portion 16a and the other end 101b connected to the outer peripheral portion of the mirror 31, while at least one of the one end 101a. Is connected to the elastic coupling portion 16 b and the other end 101 b is connected to the outer peripheral portion of the mirror 31.

  Then, the rod-like member 102 is laminated so that the mirror-side member 106 and the rod-like member 102 are alternately arranged along the mirror surface orthogonal direction with respect to the mirror-like member 106 constituting the folding member 101. Therefore, the folding member 101 is displaced along the mirror surface orthogonal direction in accordance with the temperature change (see arrow D51). Further, the two folding members 101 constituting the thermal actuator 100 are arranged so as to be vertically symmetrical in the drawing with the mirror 31 interposed therebetween. As a result, the two thermal actuators 100 are displaced in the same direction along the mirror orthogonal direction in the connection end with the mirror 31 according to the temperature change (see arrow D52).

  In the optical scanning device 1 configured as described above, the thermal actuator 100 moves the mirror 31 along the direction orthogonal to the rotation axis k, thereby changing the distance between the mirror 31 and the rotation axis k. The moment of inertia can be changed by changing the distance.

  In the embodiment described above, the thermal actuator 100 is the connecting displacement portion in the present invention, the folding member 101 is one member in the present invention, and the rod-shaped member 102 is the other member in the present invention.

(Seventh embodiment)
A seventh embodiment of the present invention will be described below with reference to the drawings. In the seventh embodiment, only parts different from the first embodiment will be described.

  The optical scanning device 1 in the seventh embodiment is the same as that in the first embodiment except that the configuration of the light reflecting unit 13 is changed. FIG. 10B is a diagram showing the configuration and operation of the light reflecting section 13 in the seventh embodiment.

  As shown in FIG. 10 (b), the light reflecting portion 13 of the seventh embodiment has a point that the mirror 31 is not elliptical but circular, and a thermal actuator 110 is provided instead of the thermal actuator 33. Except for this, the second embodiment is the same as the first embodiment.

The mirror 31 is arranged so that the opening 32a formed inside by the frame of the mirror support frame 32 and the surface 31b of the mirror 31 opposite to the mirror surface 31a face each other.
The thermal actuator 110 is configured by laminating a rod-shaped member 111 formed in a rod shape using silicon as a material and a rod-shaped member 112 formed in a rod shape using silicon oxide as a material along a direction orthogonal to the longitudinal direction. ing.

  Each of the plurality of thermal actuators 110 is disposed between the mirror 31 and the mirror support frame 32, and one end thereof is connected to the frame portion of the mirror support frame 32 and the other end is connected to the outer peripheral portion of the mirror 31. The Thereby, the mirror 31 is supported by the plurality of thermal actuators 110 so as to be disposed on the opening 32 a of the mirror support frame 32.

  In the thermal actuator 110, the rod-shaped member 112 is disposed so as to face the opening 32a of the mirror support frame 32, and the rod-shaped member 111 is disposed on the opposite side of the opening 32a across the rod-shaped member 112. Is done. The thermal actuator 110 bends toward the rod-shaped member 111 (silicon) when the temperature is lower than room temperature, and bends toward the rod-shaped member 112 (silicon oxide) when the temperature is higher than room temperature (see arrow D61).

  Therefore, the plurality of thermal actuators 110 are displaced in the same direction along the direction orthogonal to the mirror surface of the mirror 31 in accordance with the temperature change (see arrow D62).

  In the optical scanning device 1 configured as described above, the thermal actuator 110 moves the mirror 31 along the direction orthogonal to the rotation axis k, thereby changing the distance between the mirror 31 and the rotation axis k. The moment of inertia can be changed by changing the distance.

  In the embodiment described above, the mirror support frame 32 and the thermal actuator 110 are the connecting displacement portions in the present invention, and the rod-shaped members 111 and 112 are two members made of materials having different coefficients of thermal expansion in the present invention.

(Eighth embodiment)
The eighth embodiment of the present invention will be described below with reference to the drawings.
As shown in FIG. 11, the optical scanning device 401 applies a rotational driving force to the light beam scanning unit 402 that scans the light beam, the support unit 403 that supports the light beam scanning unit 402, and the light beam scanning unit 402. And a drive unit 404.

  The light beam scanning unit 402 includes an outer gimbal 411, an inner gimbal 412, a light reflecting unit 413, elastic coupling units 414a and 414b, elastic coupling units 415a and 415b, and elastic coupling units 416a and 416b.

  Among these, the light reflecting portion 413 includes a mirror 431, a mirror support frame 432, a mirror support elastic body 500, and a thermal actuator 510. The mirror 431 has an elliptical shape, and a mirror surface portion of an aluminum thin film is formed on the surface. The mirror support frame 432 has a circular frame shape, and the mirror 431 is disposed in the frame. The details of the configuration of the mirror support elastic body 500 and the thermal actuator 510 will be described later.

The inner gimbal 412 has a rectangular frame shape, and the light reflecting portion 413 is disposed in the frame. The outer gimbal 411 has a rectangular frame shape, and the inner gimbal 412 is disposed in the frame.
The elastic connecting portion 416 a is made of an elastically deformable material, and is disposed within the frame of the inner gimbal 412 to connect the light reflecting portion 413 and the inner gimbal 412. The elastic connecting portion 416b is made of an elastically deformable material, and is disposed within the frame of the inner gimbal 412. The elastic connecting portion 416b is disposed on the opposite side of the elastic connecting portion 416a with the light reflecting portion 413 interposed therebetween. The gimbal 412 is connected. The elastic coupling portion 416a and the elastic coupling portion 416b are arranged on the same straight line passing through the center of gravity JS of the light reflecting portion 413 and serve as the rotation axis k of the light reflecting portion 413. Thereby, the light reflection part 413 is comprised so that a torsional vibration is possible centering | focusing on the rotating shaft k.

  The elastic connecting portion 415a is made of an elastically deformable material, and is disposed within the frame of the outer gimbal 411, and connects the inner gimbal 412 and the outer gimbal 411. The elastic connecting portion 415b is made of an elastically deformable material, and is disposed in the frame of the outer gimbal 411. On the opposite side of the elastic connecting portion 415a with the inner gimbal 412 interposed therebetween, the inner gimbal 412 and the outer gimbal 411 are arranged. And The elastic connecting portion 415a and the elastic connecting portion 415b are arranged on the same straight line passing through the center of gravity JS of the light reflecting portion 413 and the inner gimbal 412 and serve as the rotation axis j of the light reflecting portion 413. Thus, the inner gimbal 412 is configured to be able to twist and vibrate about the rotation axis j.

  The elastic connecting portion 414a is made of an elastically deformable material, and connects the upper side 411a of the outer gimbal 411 and the support portion 403. The elastic connection portion 414b is made of an elastically deformable material, and connects the lower side 411b of the outer gimbal 411 and the support portion 403 on the opposite side of the elastic connection portion 414a with the outer gimbal 411 interposed therebetween. The elastic connecting portion 414 a and the elastic connecting portion 414 b are arranged on the same straight line passing through the center of gravity JS of the light reflecting portion 413, the inner gimbal 412, and the outer gimbal 411, and serve as the rotation axis i of the outer gimbal 411. Accordingly, the outer gimbal 411 is configured to be capable of torsional vibration about the rotation axis i.

  Next, the support portion 403 includes an upper support portion 403a connected to an end portion of the elastic connection portion 414a on the side not connected to the upper side 411a, and an end portion of the elastic connection portion 414b on the side not connected to the lower side 411b. The lower support part 403b to be connected, the left support part 403c and the right support part 403d that support the drive part 404 are configured.

  Furthermore, the drive part 404 is comprised from piezoelectric unimorph 404a, 404b, 404c, 404d. The piezoelectric unimorphs 404a, 404b, 404c, 404d are formed in a rectangular plate shape, and are arranged so that the longitudinal direction thereof is orthogonal to the rotation axis i.

  The piezoelectric unimorph 404a has one end in the longitudinal direction fixed to the left support 403c and the other end connected to the upper side 411a of the outer gimbal 411. One end of the piezoelectric unimorph 404b in the longitudinal direction is fixed to the left support 403c, and the other end is connected to the lower side 411b of the outer gimbal 411. One end of the piezoelectric unimorph 404c in the longitudinal direction is fixed to the right support portion 403d, and the other end is connected to the upper side 411a of the outer gimbal 411. The piezoelectric unimorph 404d has one end in the longitudinal direction fixed to the right support 403d and the other end connected to the lower side 411b of the outer gimbal 411.

  Accordingly, when a voltage is applied to the piezoelectric unimorphs 404a, 404b, 404c, and 404d, the end portion on the side connected to the outer gimbal 411 is bent and displaced, and the piezoelectric unimorphs 404a, 404b, 404c, and 404d are rotated along the rotation axis i. The outer gimbal 411 can be moved. A voltage is applied to the piezoelectric unimorphs 404a, 404b, 404c, and 404d through power supply lines FL1, FL2, FL3, and FL4, respectively.

  Then, the piezoelectric unimorph 404a and the piezoelectric unimorph 4b bend and vibrate in the same phase, the piezoelectric unimorph 404c and the piezoelectric unimorph 404d bend and vibrate in the same phase, and the piezoelectric unimorphs 404a and 404b and the piezoelectric unimorphs 404c and 404d are reversed. Voltage application to the piezoelectric unimorphs 404a, 404b, 404c, and 404d is controlled so as to bend and vibrate in phase. As a result, the outer gimbal 411 rotates and vibrates around the rotation axis i. Then, by vibrating the outer gimbal 411 at a predetermined resonance frequency, the light beam reflected by the mirror 431 can be two-dimensionally scanned as in the first embodiment.

Next, the mirror support elastic body 500 and the thermal actuator 510 will be described.
As shown in FIG. 12A, the mirror support elastic body 500 and the thermal actuator 510 are each disposed within the frame of the mirror support frame 432 and connect the mirror 431 and the mirror support frame 432.

  The mirror support elastic body 500 is formed in a shape in which a rod-like member is folded back evenly using silicon as a material. The mirror support elastic body 500 includes a radial member 501 extending in the direction from the mirror 431 to the mirror support frame 432 or in the direction from the mirror support frame 432 to the mirror 431 (that is, the radial direction of the circular mirror support frame 432). The circumferential members 502 extending along the circumferential direction of the mirror 431 are alternately connected to each other. The mirror support elastic body 500 has one end connected to the inner peripheral portion of the mirror support frame 432 and the other end connected to the outer peripheral portion of the mirror 431. Further, the mirror support elastic body 500 is disposed between the mirror 431 and the mirror support frame 432 so that the adjacent radial members 501 face each other along the circumferential direction of the mirror 431.

  The thermal actuator 510 includes two rod-like members 511 and 512. One end of each of the rod-like members 511 and 512 is connected to the inner peripheral portion of the mirror support frame 432 and the other end is connected to the outer peripheral portion of the mirror 431. Furthermore, the rod-like members 511 and 512 are arranged so as to be parallel to each other along a plane parallel to the mirror surface of the mirror 431.

  Further, as shown in FIG. 13, the rod-shaped members 511 and 512 include a rod-shaped member 513 formed in a rod shape using silicon as a material, an oxide film (silicon oxide in this embodiment) 514, and a piezoelectric film 516 (in this embodiment). A piezoelectric rod-like member 515 formed in a rod shape by sandwiching lead zirconate titanate (PZT) between the upper electrode 517 and the lower electrode 518 is laminated in a direction perpendicular to the longitudinal direction. Yes.

  And as shown to Fig.14 (a), a fixed voltage is always applied to the piezoelectric rod-shaped member 515. FIG. Note that a voltage is applied to the thermal actuator 510 via the feeder line FL5 (see FIG. 11).

  When the temperature does not change, the piezoelectric rod-shaped member 515 expands and contracts along the longitudinal direction of the piezoelectric rod-shaped member 515 (hereinafter referred to as the X direction) according to the applied voltage value. It is known that the value of the piezoelectric constant d31, which is a physical property value of the piezoelectric body, increases as the temperature increases. That is, when the environmental temperature changes, the value of the piezoelectric constant d31 changes, thereby changing the expansion / contraction amount of the piezoelectric body.

  For this reason, when the temperature is room temperature, as shown in FIG. 14A, when a voltage is applied to the piezoelectric rod-shaped member 515, the piezoelectric rod-shaped member 515 contracts in the X direction. Thereby, the rod-shaped members 511 and 512 bend in the stacking direction (hereinafter referred to as Z direction). Therefore, the rod-shaped members 511 and 512 have a concave shape that is recessed along the Z direction, and shrinkage in the X direction occurs.

  Under the condition where the temperature is higher than the room temperature, the piezoelectric constant d31 increases, so that the amount of contraction in the X direction of the piezoelectric rod-shaped member 515 increases as shown in FIG. Thereby, the bending to the Z direction of the rod-shaped members 511 and 512 becomes large. Therefore, the amount of shrinkage in the X direction is larger than that at room temperature (see the shrinkage amount difference ΔL1 in the figure).

  On the other hand, since the piezoelectric constant d31 is small under the condition where the temperature is lower than room temperature, the amount of contraction in the X direction of the piezoelectric rod-shaped member 515 is small as shown in FIG. Thereby, the bending to the Z direction of the rod-shaped members 511 and 512 becomes small. Therefore, the amount of shrinkage in the X direction is smaller than that at room temperature (refer to the amount of shrinkage ΔL2 in the figure).

  Therefore, in the thermal actuator 510, as shown in FIGS. 15 (a) and 15 (b), the longitudinal length L2 at the high temperature is higher than the longitudinal length L1 at the low temperature (see FIG. 15 (a)). (See FIG. 15B) is shorter.

  Therefore, for example, as shown in FIG. 12A, when the two thermal actuators 510 are arranged so as to be symmetric with respect to the rotation axis m orthogonal to the mirror surface of the mirror 431, the temperature is When the temperature is higher than the room temperature, the thermal actuator 510 contracts as shown in FIG. 12B, and the mirror 431 rotates counterclockwise about the rotation axis m (see arrow D71). On the other hand, when the temperature is lower than room temperature, the mirror 431 rotates clockwise around the rotation axis m.

  Furthermore, the mirror 431 has an elliptical shape. For this reason, as in the first embodiment, the smaller the angle formed between the major axis of the mirror 431 and the rotation axis k, the smaller the moment of inertia around the rotation axis k. Therefore, by setting the position of the mirror 431 so that the angle becomes smaller as the temperature becomes higher, the moment of inertia around the rotation axis k becomes smaller as the temperature becomes higher.

Next, a manufacturing method of the optical scanning device 401 will be described with reference to FIG.
In order to manufacture the optical scanning device 401, first, as shown in FIG. 16A, a thermal oxidation process is performed on the SOI substrate 600. The SOI substrate 600 has a structure in which a buried oxide film layer 620 and a single crystal silicon layer 630 are sequentially stacked on a silicon substrate 610. Therefore, a thermal oxide film 640 is formed on the surface of the single crystal silicon layer 630 and a thermal oxide film 650 is also formed on the back surface of the silicon substrate 610 by the above thermal oxidation treatment.

  Then, a Ti / Pt layer 660 is deposited on the thermal oxide film 640, a PZT layer 670 is further deposited on the Ti / Pt layer 660, and then patterned. Thereby, as shown in FIG. 16B, the piezoelectric film 516 and the lower electrode 518 of the thermal actuator 510 are formed.

Further, a Ti / Au layer 680 is deposited and patterned. Thereby, the upper electrode 517 of the thermal actuator 510 and the mirror surface portion 685 of the mirror 431 are formed.
Then, as shown in FIG. 16C, the single crystal silicon layer 630 in the region corresponding to the gap of the light beam scanning unit 402 (in FIG. 16C, the gap between the mirror 431 and the thermal actuator 510) is DRIE. Etch with

  Thereafter, as shown in FIG. 16D, the region corresponding to the light beam scanning unit 402 in the thermal oxide film 650 on the back surface of the silicon substrate 610 is removed by etching, and then the thermal oxide film 650 that has not been removed is removed. By etching the silicon substrate 610 as a mask, a recess 690 is formed in the silicon substrate 610.

  Also, as shown in FIG. 16E, the region of the recess 690 in the buried oxide film layer 620 and the thermal oxide film 650 on the back surface of the silicon substrate 610 are removed by etching. Thereby, the optical scanning device 401 is configured such that the light beam scanning unit 402 can rotate.

  In the optical scanning device 401 configured as described above, the thermal actuator 510 includes the rod-shaped member 513 made of the same material as the elastic coupling portions 416a and 416b and the piezoelectric film 516 between the upper electrode 517 and the lower electrode 518. The formed piezoelectric rod-shaped member 515 is laminated, and a predetermined voltage is always applied between the upper electrode 517 and the lower electrode 518.

  The piezoelectric rod-like member 515 is applied with a constant voltage between the upper electrode 517 and the lower electrode 518, so that a surface perpendicular to the direction from the upper electrode 517 to the lower electrode 518 (hereinafter referred to as electrode facing). Stretch or shrink along the surface).

  The piezoelectric constant d31, which is one of the physical property values of the piezoelectric body, is a value indicating the ease of expansion and contraction along the electrode facing surface when a voltage is applied to the piezoelectric body. It is known that the value of the constant d31 increases. That is, when the temperature changes, the value of the piezoelectric constant d31 changes, and the amount of expansion and contraction along the electrode facing surface of the piezoelectric body changes.

  For this reason, when the temperature rises, the piezoelectric rod-shaped member 515 contracts more than the rod-shaped member 513 along the electrode facing surface, so that the thermal actuator 510 formed by stacking the piezoelectric rod-shaped member 515 and the rod-shaped member 513 is an upper electrode. It bends in a direction from 517 toward the lower electrode 518. That is, as the temperature increases, the thermal actuator 510 has a shorter length along the electrode facing surface, and can automatically displace the mirror 431 to a position corresponding to the temperature.

  Accordingly, since the mirror 431 can be displaced without using a temperature sensor for detecting temperature and a control circuit for performing temperature correction based on the temperature detection result, the configuration of the optical scanning device 401 can be simplified. it can.

In addition, the piezoelectric rod-shaped member 515 has a larger amount of expansion and contraction along the electrode facing surface as the voltage value applied between the upper electrode 517 and the lower electrode 518 increases.
For this reason, the rigidity of the elastic coupling portions 416a and 416b changes with the passage of time to change the resonance frequency f of the optical scanning device 401, and the rigidity of the piezoelectric rod-like member 515 changes to expand and contract along the electrode facing surface. As the amount changes, the moment of inertia around the rotation axis k of the mirror 431 is changed by adjusting the voltage value applied between the upper electrode 517 and the lower electrode 518, and the resonance frequency f associated with secular change is changed. It becomes possible to suppress the change of.

  In order to change the moment of inertia around the rotation axis k of the mirror 431, the reflective surface of the mirror 431 has a shape other than a circle (in this embodiment, an elliptical shape), and the thermal actuator 510 is perpendicular to the reflective surface. The mirror 431 is rotated around the rotation axis m.

  That is, since the reflection surface of the mirror 431 has a shape other than a circle, the mirror 431 rotates with a point farthest from the rotation axis k along with the rotation of the mirror 431 around the rotation axis m perpendicular to the reflection surface. The distance from the axis k changes. In this embodiment, since the reflecting surface of the mirror 431 is elliptical, the major axis direction and the minor axis direction have different diameters, and the distance changes as the mirror 431 rotates. The moment of inertia can be changed by changing the distance.

  Further, the mirror support elastic body 500 is formed in a shape in which a rod-like member is folded back along the reflection surface of the mirror 431 using silicon as a material. For this reason, the mirror support elastic body 500 connects the mirror 431 and the mirror support frame 432 so that the thermal actuator 510 displaces the mirror 431 so as to prevent the surface direction along the reflection surface of the mirror 431 from changing. Then, the mirror 431 is supported.

  Thereby, it is possible to suppress the change in the scanning direction when the optical scanning device 401 scans the light beam due to the thermal actuator 510 displacing the mirror 431.

  Further, since the piezoelectric film 516 is made of lead zirconate titanate (PZT) having the largest piezoelectric constant d31 among the piezoelectric materials that are generally used, the displacement amount of the mirror 431 by the thermal actuator 510 can be increased.

  In the embodiment described above, the mirror 431 is the reflection portion in the present invention, the elastic coupling portions 416a and 416b are the first elastic deformation members in the present invention, and the inner gimbal 412 is the first support portion and the elastic coupling portions 415a and 415b in the present invention. Is the second elastic deformation member in the present invention, the outer gimbal 411 is the second support portion in the present invention, the elastic connection portions 414a and 414b are the third elastic deformation member in the present invention, and the support portion 403 is the third support portion in the present invention. is there.

  Further, the mirror support frame 432 and the thermal actuator 510 are the connecting displacement portion in the present invention, the rod-shaped member 513 is the substrate member in the present invention, the piezoelectric film 516 is the piezoelectric body in the present invention, and the upper electrode 517 and the lower electrode 518 are the first in the present invention. The first electrode, the second electrode, and the piezoelectric rod-shaped member 515 are piezoelectric members in the present invention, and the mirror support elastic body 500 is a connection support portion in the present invention.

(Ninth embodiment)
The ninth embodiment of the present invention will be described below with reference to the drawings. In the ninth embodiment, only parts different from the eighth embodiment will be described.

The optical scanning device 401 in the ninth embodiment is the same as that in the eighth embodiment except that the configuration of the light reflecting unit 413 is changed.
As shown in FIG. 17A, the light reflecting portion 413 according to the ninth embodiment is the same as the first embodiment except that the mirror support elastic body 500 is omitted and a thermal actuator 520 is provided instead of the thermal actuator 510. This is the same as the eighth embodiment.

  The thermal actuator 520 includes two rod-like members 521 and 522. One end of each of the rod-like members 521 and 522 is connected to the inner peripheral portion of the mirror support frame 432 and the other end is connected to the outer peripheral portion of the mirror 431. Further, the rod-like members 521 and 522 are arranged so as to be parallel to each other along a plane parallel to the mirror surface of the mirror 431.

  Further, as shown in FIG. 18A, the rod-shaped members 521 and 522 are composed of a rod-shaped member 523 formed in a rod shape using silicon as a material, an oxide film (not shown), and a piezoelectric film (in this embodiment, titanic acid). A piezoelectric rod-like member 524 formed in a rod shape with lead zirconate (PZT) sandwiched between an upper electrode and a lower electrode is laminated along a direction perpendicular to the longitudinal direction.

  However, in the rod-shaped member 521, the piezoelectric rod-shaped member 524 is disposed on the same side as the mirror surface of the mirror 431 with the rod-shaped member 523 interposed therebetween. In the rod-shaped member 522, the piezoelectric member is disposed on the opposite side of the mirror surface of the mirror 431 with the rod-shaped member 523 interposed therebetween. A rod-shaped member 524 is disposed.

For this reason, the direction projecting along the Z direction by contracting in the X direction is reversed between the rod-shaped member 521 and the rod-shaped member 522.
Similarly to the eighth embodiment, as shown in FIGS. 18A and 18B, the thermal actuator 520 has a higher temperature than the longitudinal length L1 at low temperatures (see FIG. 18A). The longitudinal length L2 at the time (see FIG. 18B) is shorter.

  Therefore, for example, as shown in FIG. 17A, when the two thermal actuators 520 are arranged so as to be symmetrical with respect to the rotation axis m orthogonal to the mirror surface of the mirror 431, the temperature is When the temperature becomes higher than room temperature, the thermal actuator 520 contracts as shown in FIG. 17B, and the mirror 431 rotates counterclockwise about the rotation axis m (see arrow D81). On the other hand, when the temperature is lower than room temperature, the mirror 431 rotates clockwise around the rotation axis m.

  Therefore, similarly to the eighth embodiment, the position of the mirror 431 is set so that the angle becomes smaller as the temperature becomes higher, so that the moment of inertia around the rotation axis k becomes smaller as the temperature becomes higher. be able to.

Next, a method for manufacturing the optical scanning device 401 will be described with reference to FIGS.
In order to manufacture the optical scanning device 401, first, as shown in FIG. 19A, the silicon substrate 700 is subjected to thermal oxidation treatment. As a result, a thermal oxide film 710 is formed on the surface of the silicon substrate 700, and a thermal oxide film 720 is also formed on the back surface of the silicon substrate 700.

  Then, as shown in FIG. 19B, trenches 721 and 722 for applying a voltage to the lower electrode and the upper electrode of the rod-shaped member 522 are formed in the portion where the rod-shaped member 522 is formed on the back surface side of the silicon substrate 700. To do. The trenches 721 and 722 penetrate the thermal oxide film 720 and have a bottom surface in the silicon substrate 700.

Then, by performing a thermal oxidation process, a thermal oxide film 730 is formed on the sidewalls of the trenches 721 and 722 as shown in FIG.
Thereafter, a Ti / Pt layer 740 is deposited and patterned. Further, a Ti / Au layer 750 is deposited and patterned. As a result, as shown in FIG. 19D, the Ti / Pt layer 740 is embedded in the trench 721 and the Ti / Au layer 750 is embedded in the trench 722.

  Further, a Ti / Pt layer 760 is deposited and patterned, and then a PZT layer 770 is deposited and patterned. Further, a Ti / Au layer 780 is deposited and patterned. Thereby, as shown in FIG. 19E, the piezoelectric rod-like member 524 of the rod-like member 522 is formed on the opening of the trench 721, and the Ti / Au layer 750 in the trench 722 and the upper portion of the piezoelectric rod-like member 524 are formed. The electrode is electrically connected.

  Then, as shown in FIG. 19F, an organic resin 790 is applied on the thermal oxide film 720 on the back surface side of the silicon substrate 700. Thereafter, using the organic resin 790 as an adhesive, a silicon substrate 810 having a thermal oxide film 800 formed on the back surface is bonded to the silicon substrate 700 as shown in FIG.

  Further, as shown in FIG. 19H, the surface of the silicon substrate 700 is ground and polished until the Ti / Pt layer 740 in the trench 721 and the Ti / Au layer 750 in the trench 722 are exposed.

  Thereafter, by performing thermal oxidation treatment, as shown in FIG. 20A, a thermal oxide film 820 is formed on the surface of the silicon substrate 700 other than the region where the Ti / Pt layer 740 and the Ti / Au layer 750 are exposed. Form.

  Then, a Ti / Pt layer 830 is deposited on the surface side of the silicon substrate 700 and patterned. Thereafter, a PZT layer 840 is deposited on the surface side of the silicon substrate 700 and patterned. Further, a Ti / Au layer 850 is deposited on the surface side of the silicon substrate 700 and patterned.

  Thus, as shown in FIG. 20B, a pattern of the Ti / Pt layer 830 that is electrically connected to the Ti / Pt layer 740 on the back surface side of the silicon substrate 700 is formed on the surface side of the silicon substrate 700. . Further, a pattern of the Ti / Au layer 850 that is electrically connected to the Ti / Au layer 750 on the back surface side of the silicon substrate 700 is formed on the front surface side of the silicon substrate 700. Further, the piezoelectric rod-shaped member 524 of the rod-shaped member 521 and the mirror surface portion 855 of the mirror 431 are formed on the surface side of the silicon substrate 700.

  Then, as shown in FIG. 20C, the silicon substrate 700 in the region corresponding to the gap of the light beam scanning unit 2 (the gap between the mirror 431 and the thermal actuator 520 in FIG. 20C) is etched by DRIE. To do.

  Thereafter, as shown in FIG. 20D, a region corresponding to the light beam scanning unit 2 in the thermal oxide film 800 on the back surface of the silicon substrate 810 is removed by etching, and then the thermal oxide film 800 that has not been removed is removed. By etching the silicon substrate 810 as a mask, a recess 860 is formed in the silicon substrate 810.

  Further, as shown in FIG. 20E, the region of the recess 860 in the organic resin 790 is removed by etching. Then, as shown in FIG. 20F, the region of the recess 860 in the thermal oxide film 720 and the thermal oxide film 800 on the back surface of the silicon substrate 810 are removed by etching. Accordingly, the optical scanning device 401 is configured such that the light beam scanning unit 402 can rotate.

  In the optical scanning device 401 configured as described above, the bar-shaped members 521 and 522 constituting the thermal actuator 520 are arranged in the X-direction so as to protrude along the Z-direction in the bar-shaped member 521 and the bar-shaped member 522. The reverse is true. For this reason, the thermal actuator 520 connects the mirror 431 and the mirror support frame 432 so as to prevent the thermal actuator 520 from displacing the mirror 431 so that the surface direction along the reflection surface of the mirror 431 is changed. The mirror 431 is supported.

  Thereby, it is possible to suppress a change in the scanning direction when the optical scanning device 401 scans the light beam due to the thermal actuator 520 displacing the mirror 431.

  In the embodiment described above, the mirror support frame 432 and the thermal actuator 520 are the connecting displacement portion in the present invention, the rod-shaped member 523 is the substrate member in the present invention, and the piezoelectric rod-shaped member 524 is the piezoelectric member in the present invention.

(10th Embodiment)
The tenth embodiment of the present invention will be described below with reference to the drawings. Note that in the tenth embodiment, only parts different from the eighth embodiment will be described.

The optical scanning device 401 in the tenth embodiment is the same as that in the eighth embodiment except that the configuration of the light reflecting unit 413 is changed.
As shown in FIG. 21A, the light reflecting portion 413 of the tenth embodiment includes an elliptical mirror 431 disposed so that its long axis LA and the rotation axis k are orthogonal to each other, and the mirror The eighth embodiment is the same as the eighth embodiment except that a mirror support elastic body 530 is provided instead of the support elastic body 500 and a thermal actuator 540 is provided instead of the thermal actuator 510.

  The mirror support elastic body 530 is a curved rod-shaped member made of silicon. The mirror support elastic body 530 has one end connected to the inner periphery of the mirror support frame 432 and the other end connected to the outer periphery of the mirror 431.

  The thermal actuator 540 is a rod-shaped member formed by sandwiching a rod-shaped member made of silicon as a material, an oxide film, and a piezoelectric film (in this embodiment, lead zirconate titanate (PZT)) between an upper electrode and a lower electrode. The piezoelectric rod-shaped members formed in the above are stacked along a direction orthogonal to the longitudinal direction.

The thermal actuator 540 is disposed between the mirror 431 and the mirror support frame 432 so that the longitudinal direction thereof is parallel to the major axis LA of the mirror 431.
Therefore, the thermal actuator 540 expands and contracts along the major axis direction of the mirror 431 according to the temperature change.

  For example, as shown in FIG. 21A, the thermal actuator 540 and the mirror 431 are arranged so that the short axis SA of the mirror 431 is arranged on the opposite side of the thermal actuator 540 across the rotation axis k at low temperatures. When the temperature rises by connecting the two, the point farthest from the rotation axis k (see point P91) and the rotation axis k of the peripheral part of the elliptical mirror 431, as shown in FIG. (See the distance I91) (see the arrow D91), and the moment of inertia around the rotation axis k is reduced.

  Therefore, by connecting the thermal actuator 540 and the mirror 431 so that the above distance becomes smaller as the temperature becomes higher, the moment of inertia around the rotation axis k becomes smaller as the temperature becomes higher.

  In the optical scanning device 401 configured as described above, the thermal actuator 540 moves the mirror 431 along a direction orthogonal to the rotation axis k, thereby changing the distance between the mirror 431 and the rotation axis k. The moment of inertia can be changed by changing the distance.

  The mirror support elastic body 530 is formed in a shape in which a rod-like member is curved along the reflection surface of the mirror 431 using silicon as a material. For this reason, the mirror support elastic body 530 connects the mirror 431 and the mirror support frame 432 so that the thermal actuator 540 displaces the mirror 431 so as to prevent the surface direction along the reflection surface of the mirror 431 from changing. Then, the mirror 431 is supported.

  Thereby, it is possible to suppress a change in the scanning direction when the optical scanning device 401 scans the light beam due to the thermal actuator 540 displacing the mirror 431.

In the embodiment described above, the mirror support frame 432 and the thermal actuator 540 are connection displacement portions in the present invention, and the mirror support elastic body 530 is a connection support portion in the present invention.
(Eleventh embodiment)
The eleventh embodiment of the present invention will be described below with reference to the drawings. In the eleventh embodiment, only parts different from the eighth embodiment will be described.

The optical scanning device 401 in the eleventh embodiment is the same as that in the eighth embodiment except that the configuration of the light reflecting unit 413 is changed.
As shown in FIG. 22A, the light reflecting portion 413 of the eleventh embodiment includes an elliptical mirror 431 disposed so that its long axis LA and the rotation axis k are orthogonal to each other, and the mirror The eighth embodiment is the same as the eighth embodiment except that a mirror support elastic body 550 is provided instead of the support elastic body 500, a lever portion 560 is added, and a thermal actuator 570 is provided instead of the thermal actuator 510. The same.

  The mirror support elastic body 550 is formed in a shape in which a plurality of bar-shaped members are folded back using silicon as a material. The mirror support elastic body 550 includes a radial member 551 that extends in the direction from the mirror 431 toward the mirror support frame 432 or the direction from the mirror support frame 432 toward the mirror 431 (that is, the radial direction of the circular mirror support frame 432). The circumferential members 552 extending along the circumferential direction of the mirror 431 are alternately connected to each other. The mirror support elastic body 550 has one end connected to the inner peripheral portion of the mirror support frame 432 and the other end connected to the outer peripheral portion of the mirror 431. Further, the mirror support elastic body 550 is disposed between the mirror 431 and the mirror support frame 432 such that adjacent circumferential members 552 face each other along the radial direction of the mirror support frame 432.

  The lever portion 560 is disposed between the mirror 431 and the mirror support frame 432 on both sides of the major axis LA of the mirror 431. And the lever part 560 is formed in the shape provided with the connection block 561, the elastic link 562, the connection block support elastic body 563, and the elastic link support body 564 by using silicon as a material.

The connection block 561 is disposed between the mirror 431 and the mirror support frame 432 and is connected to the thermal actuator 570.
The elastic link 562 is disposed between the connection block 561 and the mirror 431, and one end thereof is connected to the connection block 561 and the other end is connected to the outer peripheral portion of the mirror 431.

  The connection block support elastic body 563 is disposed between the connection block 561 and the mirror support frame 432, and one end thereof is connected to the connection block 561 and the other end is connected to the inner periphery of the mirror support frame 432.

  The elastic link support 564 is disposed between the elastic link 562 and the mirror support frame 432, and one end thereof is connected to the elastic link 562 and the other end is connected to the inner peripheral portion of the mirror support frame 432.

  The thermal actuator 570 has a rod-like member formed of a rod-like member made of silicon, an oxide film, and a piezoelectric film (in this embodiment, lead zirconate titanate (PZT)) between the upper electrode and the lower electrode. The piezoelectric rod-shaped members formed in the above are stacked along a direction orthogonal to the longitudinal direction.

  The thermal actuator 570 is disposed between the connection block 561 and the mirror support frame 432 so that the longitudinal direction thereof is parallel to the major axis LA of the mirror 431, and one end thereof is connected to the connection block 561. The other end is connected to the inner periphery of the mirror support frame 432. Therefore, the thermal actuator 540 expands and contracts along the major axis direction of the mirror 431 according to the temperature change.

  Then, for example, as shown in FIG. 22 (a), at low temperatures, heat is transmitted through the lever portion 560 so that the short axis SA of the mirror 431 is disposed on the same side as the thermal actuator 570 with the rotation axis k interposed therebetween. When the temperature rises by connecting the actuator 570 and the mirror 431, as shown in FIG. 22B, the point (the point P101 that is farthest from the rotation axis k in the peripheral part of the elliptical mirror 431). The distance between the rotation axis k and the rotation axis k (see the distance I101) is shortened (see the arrow D101), and the moment of inertia around the rotation axis k is reduced.

  Therefore, by connecting the thermal actuator 570 and the mirror 431 so that the distance becomes smaller as the temperature becomes higher, the moment of inertia around the rotation axis k becomes smaller as the temperature becomes higher.

  In the optical scanning device 401 configured as described above, the thermal actuator 570 moves the mirror 431 along the direction orthogonal to the rotation axis k, thereby changing the distance between the mirror 431 and the rotation axis k. The moment of inertia can be changed by changing the distance.

  The elastic link 562 and the elastic link support 564 form a lever mechanism. That is, when the connection block 561 located at one end of the elastic link 562 is displaced by the thermal actuator 570, the mirror 431 with the connection point 565 (see FIG. 22A) between the elastic link support 564 and the elastic link 562 as a fulcrum. Is displaced.

  Then, by making the distance from the thermal actuator 570 to the connection point 565 (fulcrum) shorter than the distance from the connection point 565 (fulcrum) to the mirror 431, even if the displacement of the thermal actuator 570 is small, the displacement of the mirror 431 is reduced. Can be bigger.

  Further, the mirror support elastic body 550 is formed in a shape in which a rod-like member is folded back a plurality of times along the reflection surface of the mirror 431 using silicon as a material. For this reason, the mirror support elastic body 550 connects the mirror 431 and the mirror support frame 432 so as to prevent the thermal actuator 570 from displacing the mirror 431 so that the surface direction along the reflection surface of the mirror 431 is changed. Then, the mirror 431 is supported.

  Thereby, it is possible to suppress the change in the scanning direction when the optical scanning device 401 scans the light beam due to the thermal actuator 570 displacing the mirror 431.

In the embodiment described above, the mirror support frame 432 and the thermal actuator 570 are connection displacement portions in the present invention, and the mirror support elastic body 550 is a connection support portion in the present invention.
(Twelfth embodiment)
The twelfth embodiment of the present invention will be described below with reference to the drawings. In the twelfth embodiment, only parts different from the eighth embodiment will be described.

The optical scanning device 401 in the twelfth embodiment is the same as that in the eighth embodiment except that the configuration of the light reflecting unit 413 is changed.
As shown in FIG. 23, the light reflecting portion 413 of the twelfth embodiment is provided with a point that the mirror 431 is circular instead of elliptical, and a thermal actuator 580 is provided instead of the mirror support elastic body 500 and the thermal actuator 510. Except for these points, the second embodiment is the same as the first embodiment.

  As shown in FIG. 24A, the mirror 431 is arranged so that the opening 432a formed inside by the frame of the mirror support frame 432 and the surface 431b of the mirror 431 opposite to the mirror surface 431a face each other. Is done.

The thermal actuator 580 includes a specular direction member 581, a specular direction member 582, and a piezoelectric rod-shaped member 583.
The mirror surface orthogonal direction member 581 is a direction orthogonal to the mirror surface of the mirror 431 from the frame of the mirror support frame 432 toward the side where the mirror 431 is disposed with the mirror support frame 432 interposed therebetween (see arrow D111). Hereinafter, it extends along a mirror surface orthogonal direction).

  The mirror surface direction member 582 extends along a direction parallel to the mirror surface of the mirror 431 (hereinafter referred to as a mirror surface direction). One end of the mirror surface direction member 582 is connected to the end portion of the mirror surface orthogonal direction member 581 on the side not connected to the mirror support frame 432, and the other end is connected to the outer peripheral portion of the mirror 431. Accordingly, the mirror 431 is supported by the plurality of thermal actuators 580 so as to be disposed on the opening 432a of the mirror support frame 32.

  The piezoelectric rod-shaped member 583 is formed in a rod shape by sandwiching a piezoelectric film (in this embodiment, lead zirconate titanate (PZT)) between the upper electrode and the lower electrode. The piezoelectric rod-like member 583 is stacked on the mirror surface direction member 582 via an oxide film (not shown).

  In the thermal actuator 580, the mirror direction member 582 is disposed so as to face the opening 432a of the mirror support frame 432, and the piezoelectric rod-shaped member 583 is disposed on the same side as the opening 432a on the mirror surface member 582. Is done.

  As a result, when the temperature of the thermal actuator 580 increases, the mirror surface direction member 582 and the piezoelectric rod-shaped member 583 are flexed in the Z direction as shown in FIG. The mirror 431 moves along the direction perpendicular to the mirror surface so that the distance to k becomes smaller, and the moment of inertia around the rotation axis k becomes smaller.

  In the optical scanning device 401 configured as described above, the thermal actuator 580 moves the mirror 31 along the direction orthogonal to the rotation axis k, thereby changing the distance between the mirror 431 and the rotation axis k. The moment of inertia can be changed by changing the distance.

  In the embodiment described above, the mirror support frame 432 and the thermal actuator 580 are the connecting displacement portion in the present invention, the mirror surface direction member 582 is the substrate member in the present invention, and the piezoelectric rod-shaped member 583 is the piezoelectric member in the present invention.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, As long as it belongs to the technical scope of this invention, a various form can be taken.
For example, in the above embodiment, the combination of silicon and silicon oxide is shown as the thermal actuator. However, any material other than silicon oxide can be selected as long as it has a different coefficient of thermal expansion from that of silicon. For example, a metal material such as aluminum or a resin material such as polyimide or SU8 may be used.

  In the above embodiment, in the thermal actuator placement region 331 shown in FIG. 5E, the device layer etching region 342 on the left side of the thermal actuator placement region 331 has a device layer left on the left side of the thermal actuator placement region 331 by DRIE. On the other hand, the device layer etching region 342 on the right side of the thermal actuator placement region 331 shows that the device layer is formed on the right side of the thermal actuator placement region 331 by DRIE (see FIG. 5 (g)). However, in consideration of mask misalignment, the device layer etching region 342 on the right side of the thermal actuator placement region 331 may be formed by shifting by several μm so that the device layer remains on the right side of the thermal actuator placement region 331 by DRIE. Good.

In the above embodiment, the optical scanning device 1 constituting the three-degree-of-freedom coupled vibration system is applied. However, the connecting displacement portion of the present invention may be applied to the optical scanning device described below.
FIG. 25 is a plan view showing a configuration of an optical scanning device 201 according to an embodiment to which the present invention is applied.

  As shown in FIG. 25, the optical scanning device 201 applies a rotational driving force to the light beam scanning unit 202 that scans the light beam, the support unit 203 that supports the light beam scanning unit 202, and the light beam scanning unit 202. And a drive unit 204.

  The light beam scanning unit 202 includes a gimbal 211, a light reflecting unit 212, elastic coupling units 213a and 213b, elastic coupling units 214a and 214b, and comb electrode units 215, 216, 217, and 218.

Among these, the light reflection part 212 is comprised from the mirror 31, the mirror support frame 32, and the thermal actuator 33 similarly to the light reflection part 13 of 1st Embodiment.
The gimbal 211 has a rectangular frame shape, and the light reflecting portion 212 is disposed in the frame.

  The elastic connecting portion 214 a is made of an elastically deformable material, and is disposed within the frame of the gimbal 211 to connect the light reflecting portion 212 and the gimbal 211. The elastic connecting portion 214b is made of an elastically deformable material, and is disposed within the frame of the gimbal 211. The light reflecting portion 212 and the gimbal 211 are opposite to the elastic connecting portion 214a across the light reflecting portion 212. And The elastic coupling part 214a and the elastic coupling part 214b serve as the rotation axis k of the light reflecting part 212. Thereby, the light reflection part 212 is comprised so that a torsional vibration is possible centering | focusing on the rotating shaft k.

  The elastic connection portion 213a is made of an elastically deformable material, and connects the upper side 211a of the gimbal 211 and the support portion 203. The elastic connecting portion 213b is made of an elastically deformable material, and connects the lower side 211b of the gimbal 211 and the support portion 203 on the opposite side of the elastic connecting portion 213a across the gimbal 211. The elastic connecting portion 213a and the elastic connecting portion 213b serve as the rotation axis i of the gimbal 211. As a result, the gimbal 211 is configured to be capable of torsional vibration about the rotation axis i.

  The comb electrode portion 215 is formed in a comb shape along the lower semicircular portion of the mirror support frame 32. Further, the comb electrode portion 216 is formed in a comb shape along the upper semicircular portion of the mirror support frame 32.

  The comb electrode portion 217 is formed in a comb shape along the left side 211 c of the gimbal 211. Further, the comb electrode portion 218 is formed in a comb shape along the right side 211 d of the gimbal 211.

  Next, the drive unit 204 includes comb-shaped electrode portions 204a, 204b, 204c, and 204d formed in a comb-tooth shape that meshes with the comb-shaped electrode portions 215, 216, 217, and 218 at a predetermined interval.

  Next, the support portion 203 includes an upper support portion 203a that is connected to an end portion of the elastic connection portion 213a that is not connected to the upper side 211a, and an end portion of the elastic connection portion 213b that is not connected to the lower side 211b. The lower support portion 203b to be connected, the left support portion 203c connected to the end portion of the comb electrode portion 204c on the side not facing the comb electrode portion 217, and the comb electrode portion 218 are not opposed. It is comprised from the right side support part 203d connected with the edge part of the side comb-tooth electrode part 204d.

The comb electrode portions 204a and 204b are connected to the gimbal 211 in a state of being arranged so as to mesh with the comb electrode portions 215 and 216.
In the optical scanning device 201 configured as described above, by applying a pulse voltage between the comb electrode portions 215 and 216 and the comb electrode portions 204a and 204b, an electrostatic attractive force that periodically changes is generated. When the elastic connecting portions 214a and 214b are elastically deformed and twisted, the light reflecting portion 212 reciprocally vibrates about the elastic connecting portions 214a and 214b as the rotation axis k. Further, by applying a pulse voltage between the comb electrode portions 217 and 218 and the comb electrode portions 204c and 204d, an electrostatic attractive force that periodically changes is generated, and the elastic coupling portions 213a and 213b are elastically deformed. By being twisted, the gimbal 211 reciprocally vibrates about the elastic coupling portions 213a and 213b as the rotation axis i.

  According to the optical scanning device 201 configured as described above, the light beam reflected by the mirror 31 is two-dimensionally scanned by swinging about the rotation axis k and swinging about the rotation axis i. be able to. Further, in the optical scanning device 201, the mirror support frame 32 and the thermal actuator 33 connect the mirror 31 and the elastic connecting portions 214a and 214b, and the moment of inertia around the rotation axis k of the mirror 31 decreases as the temperature increases. Thus, the mirror 31 can be displaced. Accordingly, by reducing the moment of inertia around the rotation axis k of the mirror 31 in response to a decrease in Young's modulus accompanying a temperature increase, it is possible to suppress a change in the resonance frequency accompanying a temperature increase. Thereby, the change of the scanning characteristic by the temperature change can be suppressed.

  The elastic connection portions 214a and 214b are the first elastic deformation member in the present invention, the gimbal 211 is the first support portion in the present invention, the elastic connection portions 213a and 213b are the second elastic deformation member in the present invention, and the rotation shaft i is the main shaft. The 2nd rotating shaft in this invention and the support part 203 are the 2nd support parts in this invention.

In the above-described embodiment, the optical scanning device 401 constituting the three-degree-of-freedom coupled vibration system is applied. However, the connecting displacement portion of the present invention may be applied to the optical scanning device described below.
As shown in FIG. 26, the optical scanning device 901 includes a light reflecting portion 413 according to the eighth embodiment instead of the light reflecting portion 212, and piezoelectric unimorphs 904a and 904b instead of the comb electrode portions 204a and 204b. Is provided to vibrate the light reflecting portion 413 about the rotation axis k, and piezoelectric unimorphs 904c and 904d are provided instead of the comb electrode portions 204c and 204d to vibrate the light reflecting portion 413 about the rotation axis i. The other points are the same as those of the optical scanning device 201.

  In addition, voltages are applied to the piezoelectric unimorphs 904a, 904b, 904c, and 904d through power supply lines FL11, FL12, FL13, and FL14, respectively, and voltages are applied to the thermal actuator 510 of the light reflecting portion 413 through the power supply line FL15. Is done.

  DESCRIPTION OF SYMBOLS 1,401,901 ... Optical scanning device, 2 ... Light beam scanning part, 3 ... Support part, 4 ... Drive part, 5 ... Angle detection part, 11 ... Outer gimbal, 12 ... Inner gimbal, 13,413 ... Light reflection part 14a, 14b, 15a, 15b, 16a, 16b, 416a, 416b ... elastic connecting part, 17, 18, 19, 20 ... comb electrode part, 31 ... mirror, 32, 432 ... mirror support frame, 33, 60, 70, 80, 90, 100, 110, 510, 520, 540, 570, 580 ... thermal actuator, 41 ... drive signal generation circuit, 42 ... amplification circuit, 43 ... CV conversion circuit, 44 ... semiconductor laser, 45 ... Control circuit, 51, 52, 62, 72, 82, 91, 92, 102, 111, 112 ... Bar-shaped member, 61, 71, 81, 91, 101 ... Folding member, 201 ... Optical scanning device, 202 ... Light beam scanning Part 203 ... support part 204 ... drive part 211 ... Nbaru, 212 ... light reflection portion, 213a, 213b, 214a, 214b ... elastic connecting portions, 215,216,217,218 ... interdigital transducers

Claims (11)

A reflecting portion (31, 431) having a reflecting surface for reflecting the light beam;
A first elastic deformation member (16a, 16b, 214a, 214b, 416a, 416b) serving as a first rotation shaft for torsionally vibrating the reflecting portion;
An optical scanning device (1, 201, 401, 901) that scans the light beam reflected by the reflecting surface by swinging the reflecting portion about the first rotation axis,
A connecting displacement portion (32, 32) that connects the reflecting portion and the first elastically deformable member and displaces the reflecting portion so that the moment of inertia of the reflecting portion around the first rotation axis decreases as the temperature increases. 432, 33, 60, 70, 80, 90, 100, 110, 510, 520, 540, 570, 580). The reflective surface of the reflective portion has a shape other than a circle,
The connection displacement portion (32, 432, 33, 60, 70, 510, 520) rotates the reflection portion as a displacement of the reflection portion around a displacement rotation axis that is a rotation axis perpendicular to the reflection surface. The optical scanning device according to claim 1. The connection displacement portion (32, 432, 80, 90, 100, 110, 540, 570, 580) moves the reflection portion along the direction orthogonal to the first rotation axis as the displacement of the reflection portion. The optical scanning device according to claim 1. The connecting displacement portion (32, 33, 60, 70, 80, 90, 100, 110)
The optical scanning device according to claim 1, wherein at least two members made of materials having different coefficients of thermal expansion are stacked. The two members are:
The optical scanning device according to claim 4, wherein the optical scanning device is a member made of silicon and a member made of silicon oxide formed by thermally oxidizing silicon. The connecting displacement portion (32, 60, 70)
Constructed by laminating two members made of materials with different coefficients of thermal expansion,
Of the two members made of materials with different coefficients of thermal expansion,
One member (61, 71, 81, 101) is formed in a shape in which a bar-shaped member is folded back a plurality of times so that the folded portion is U-shaped,
The other member (62, 72, 82, 102) is laminated on the one member formed in the folded shape so that the one member and the other member are alternately arranged. The optical scanning device according to claim 4, wherein: The connecting displacement portion (432, 510, 520, 540, 570, 580)
A substrate member (513, 523, 582) made of the same material as the first elastic deformation member (416a, 416b) and a piezoelectric body (516) between the first electrode (517) and the second electrode (518). It is configured by laminating piezoelectric members (515, 524, 583) formed by being sandwiched,
4. The optical scanning device according to claim 1, wherein a constant voltage set in advance is always applied between the first electrode and the second electrode. 5. . The reflection part and the connection displacement part are connected to suppress the change of the surface direction along the reflection surface by the connection displacement part displacing the reflection part (431). The optical scanning device according to claim 7, further comprising a connection support portion (500, 530, 550) for supporting. The optical scanning device according to claim 7, wherein the piezoelectric body is made of lead zirconate titanate (PZT). A first support part (211) for supporting the first elastic deformation member (214a, 214b);
A second elastically deformable member (213a, 213b) that is elastically deformable connected to the first support part, and the first support part is swingably supported by using the second elastically deformable member as a second rotating shaft. A second support part (203)
The second rotation axis is arranged to intersect the first rotation axis,
The first support portion is swung about the second rotation axis, and the reflection portion is swung about the first rotation axis, so that the light beam reflected by the reflection surface is 2 The optical scanning device (201, 901) according to any one of claims 1 to 9, wherein scanning is performed in a dimension. A first support part (12, 412) for supporting the first elastic deformation member (16a, 16b, 416a, 416b);
There is a second elastically deformable member (15a, 15b, 415a, 415b) that is elastically deformable connected to the first support part, and the first support part is rocked using the second elastic deformable member as a second rotating shaft. A second support portion (11, 411) for movably supporting;
There is a third elastically deformable member (14a, 14b, 414a, 414b) that is elastically deformable connected to the second support part, and the second support part is rocked using the third elastic deformable member as a third rotating shaft. A third support portion (3,403) that is movably supported;
The second rotation axis is arranged to intersect the first rotation axis,
The third rotation axis is arranged to intersect the first rotation axis and the second rotation axis,
The reflective portion (31, 431), the first support portion, the second support portion, the third support portion, the first elastic deformation member, the elastic deformation member, and the third elastic deformation member are unique. A three-degree-of-freedom coupled vibration system that torsionally vibrates at a large rotation angle when a periodic external force is applied,
By causing the inherent periodic external force to act on the three-degree-of-freedom coupled vibration system, the second support portion is swung about the third rotation axis, and the second rotation axis is the center. The light beam reflected by the reflecting surface is scanned two-dimensionally by swinging the first support portion and further swinging the reflection portion about the first rotation axis. The optical scanning device (1, 401) according to any one of claims 1 to 9.