Support substrate, module, and optical scanning device

Abstract

A support substrate according to the present disclosure supports a vibration body. In the support substrate, when the vibration body is driven in a prescribed vibration mode, a region serving as a node of vibration includes a pair of non-parallel regions that extend nonparallel to a linear region in which the amount of displacement is zero in the vibration body. In each of the pair of non-parallel regions, an external attachment part that is to be attached to an external attachment object is provided.

Description

Support substrate, module, and optical scanning device

[0001] The technology of the present disclosure relates to a support substrate, a module, and an optical scanning device.

[0002] Micromirror devices (also called microscanners) are known as one type of microelectromechanical systems (MEMS) device fabricated using silicon (Si) microfabrication technology. Because these micromirror devices are small and consume little power, they are expected to be widely used in laser displays, laser projectors, optical coherence tomography, and other applications.

[0003] There are various drive methods for micromirror devices, but the piezoelectric drive method, which uses the deformation of a piezoelectric material, is considered promising because it generates a higher torque than other methods and can achieve a wide scan angle. In particular, when a wide scan angle is required, such as in laser displays, a wider scan angle can be achieved by resonantly driving a piezoelectric micromirror device.

[0004] A typical micromirror device used in a laser display includes a mirror portion and a piezoelectric actuator (see, for example, Japanese Patent Application Laid-Open No. 2023-039221). The mirror portion is freely oscillating around a first axis and a second axis that are orthogonal to each other. The actuator is a driving unit that oscillates the mirror portion around the first axis and the second axis in response to an externally supplied driving voltage.

[0005] The micromirror device described above is housed in a package, and the package housing the micromirror device is supported by a support substrate such as a PCB (Printed Circuit Board). This support substrate is attached to an external object such as a base substrate. The support substrate is provided with external attachment portions such as screw holes for attachment to the object.

[0006] However, when the mirror of a micromirror device oscillates, vibrations are generated in the package, support substrate, and mounting object, which can cause fluctuations in the device's characteristics. For example, the vibrations propagate to the outside world, dissipating energy during resonance and reducing the mirror's deflection angle. The amount of such fluctuations in characteristics varies greatly depending on factors such as the state of fixation of the micromirror device. Furthermore, if the sound generated by the vibrations is within the human audible range, it can be unpleasant for humans.

[0007] In order to suppress the propagation of vibrations caused by the vibrating body to the outside world, it is thought to be effective to confine the vibrations within the system consisting of the micromirror device, package, and support substrate by suppressing the propagation of vibrations from the support substrate to the object to which it is attached.

[0008] The technology of the present disclosure aims to provide a support substrate, a module, and an optical scanning device that can suppress propagation of vibrations caused by a vibrating body to the outside world.

[0009] In order to achieve the above object, the support substrate of the present disclosure is a support substrate that supports a vibrating body, and when the vibrating body is driven in a specified vibration mode, the region that becomes the node of the vibration includes a pair of non-parallel regions that do not extend parallel to the linear region in the vibrating body where the displacement amount is zero, and each of the pair of non-parallel regions is provided with an external mounting portion for mounting to an external mounting object.

[0010] The external attachment portion is preferably a screw hole or a through hole.

[0011] The external attachment portions are preferably arranged at positions facing each other with the fixing region where the vibrating body is fixed as the center.

[0012] The pair of non-parallel regions defines a resonance frequency of the n-th resonance mode among the resonance modes that are generated when a torque is applied to the fixed region to which the vibrating body is fixed so as to generate a displacement that has a common spatial symmetry with the vibration mode, as ω ｎ The maximum displacement in the Z direction at the coordinates (X, Y) is Z ｎ (X, Y), and the frequency of the vibration mode is ω ｍ In this case, Z represented by the following formula (1) ｍIt is preferable that (X, Y) is included in the region where it is zero.

[0013]

[0014] A module according to the present disclosure includes the above-described support substrate and a vibrating body supported by the support substrate.

[0015] Preferably, the vibrating body includes a mirror device and a package that houses the mirror device, and the mirror device includes a movable part that includes a mirror portion that reflects incident light, and a drive part that is connected to the movable part and causes the mirror portion to oscillate around at least one oscillation axis.

[0016] The vibration mode preferably occurs when the mirror portion is oscillated around the oscillation axis.

[0017] The module according to claim 7, wherein the movable section includes a pair of first support sections connected to the mirror section and arranged on the first axis, and a pair of movable frames connected to the pair of first support sections and facing each other across the first axis, and the oscillation axis is preferably the first axis.

[0018] It is preferable that the drive unit is connected to the movable frame on a second axis intersecting the first axis and comprises a pair of second support parts that support the movable unit, and that the pair of second support parts are arranged on the second axis.

[0019] The external mounting portion is arranged in a region where a first region that becomes a node of vibration when the mirror portion is oscillated around a first axis and a second region that becomes a node of vibration when the mirror portion is oscillated around a second axis overlap, and it is preferable that the pair of non-parallel regions be included in the first region.

[0020] The driving section preferably includes a first actuator connected to the pair of second support sections and having a pair of first piezoelectric elements facing each other across the second axis.

[0021] The driving section preferably includes a second actuator that is disposed surrounding the first actuator and has a pair of second piezoelectric elements that face each other across the first axis.

[0022] The optical scanning device of the present disclosure is an optical scanning device comprising the above-mentioned support substrate, a vibrating body supported by the support substrate, and a processor that drives the vibrating body, wherein the vibrating body is configured to include a mirror device including a mirror portion that reflects incident light, and a package that houses the mirror device, and the mirror device includes a drive portion that oscillates the mirror portion in response to a drive signal provided by the processor.

[0023] According to the technology of the present disclosure, it is possible to provide a support substrate, a module, and an optical scanning device that are capable of suppressing propagation of vibrations caused by a vibrating body to the outside world.

[0024] 8 is a diagram illustrating a schematic view of an optical scanning device according to an embodiment. FIG. 9 is a block diagram illustrating an example of the hardware configuration of a drive control unit. FIG. 10 is a plan view of a micromirror device according to an embodiment, viewed from the light incident side. FIG. 11 is a cross-sectional view taken along line A-A in FIG. 3. FIG. 12 is a cross-sectional view illustrating a state in which the mirror section is rotated around a first axis. FIG. 13 is a diagram illustrating an example of a first drive signal and a second drive signal. FIG. 14 is a plan view illustrating an example of a support substrate. FIG. 15 is a plan view illustrating a state in which the support substrate is attached to a base substrate. FIG. 16 is a cross-sectional view taken along line B-B in FIG. 13. FIG. 17 is a plan view illustrating a simulation result of the amount of displacement of the support substrate when the mirror section is oscillated around the first axis. FIG. 18 is a plan view illustrating a simulation result of the amount of displacement of the support substrate when the mirror section is oscillated around a second axis. FIG. 19 is a diagram illustrating in more detail the arrangement of two screw holes. FIG. 19 is a diagram illustrating a vibration simulation using a support substrate. FIG. 19 is a contour diagram illustrating an example of a group of resonance modes generated in the support substrate. FIG. 19 is a contour diagram illustrating an example of the displacement of the support substrate when the vibrator is driven. FIG. 19 is a plan view of a support substrate according to a second embodiment. FIG. 19 is a plan view illustrating a simulation result of the amount of displacement of the support substrate when the mirror section is oscillated around the first axis. Fig. 10 is a plan view showing a simulation result of the amount of displacement of the support substrate when the mirror section is swung around a second axis. Fig. 11 is a plan view showing a support substrate according to a comparative example. Fig. 12 is a plan view showing a simulation result of the amount of displacement of the support substrate when the mirror section is swung around a first axis. Fig. 13 is a plan view showing a simulation result of the amount of displacement of the support substrate when the mirror section is swung around a second axis. Fig. 14 is a diagram showing a simulation result of the maximum amount of displacement of the base substrate when the support substrate according to the comparative example, the first embodiment, and the second embodiment is fixed to the base substrate.

[0025] An example of an embodiment of the technology of the present disclosure will be described with reference to the accompanying drawings.

[0026] First Embodiment Fig. 1 schematically illustrates an optical scanning device 10 according to a first embodiment. The optical scanning device 10 includes a micro mirror device (MMD) 2, a light source 3, and a drive controller 4. The optical scanning device 10 optically scans a surface 5 to be scanned by reflecting a light beam LB emitted from the light source 3 using the MMD 2 under the control of the drive controller 4. The surface 5 to be scanned may be a screen, the retina of an eye, or the like. The MMD 2 is an example of a "mirror device" according to the technology of the present disclosure.

[0027] MMD2 is the first axis a １ and the first axis a １ A second axis a perpendicular to ２ The micromirror device is a piezoelectric two-axis drive type that can oscillate the mirror portion 20 (see FIG. 3) around the first axis a. １ The direction parallel to this is the X direction, and the second axis a ２ The direction parallel to the axis a is the Y direction. １ and the second axis a ２ In this embodiment, the direction perpendicular to the first axis a is called the Z direction. １ and the second axis a ２ The example shows an example in which the first axis a and the second axis b are perpendicular to each other. １ and the second axis a ２ The angles may intersect at an angle other than 90°. Here, "perpendicular" means that the angles intersect within a certain angle range including a tolerance, with 90° as the center.

[0028] As will be described in more detail below, the MMD 2 is housed in a package 60 made of ceramic or the like (see FIG. 8). The package 60 housing the MMD 2 is supported by a support substrate 70 such as a PCB, and the support substrate 70 is screwed to a base substrate 80 (see FIG. 8).

[0029] The light source 3 is a laser device that emits, for example, laser light as the light beam LB. It is preferable that the light source 3 irradiates the light beam LB perpendicularly to a reflecting surface 20A (see FIG. 3 ) of the mirror portion 20 when the mirror portion 20 of the MMD 2 is stationary.

[0030] The drive control unit 4 outputs drive signals to the light source 3 and the MMD 2 based on the optical scanning information. The light source 3 generates a light beam LB based on the input drive signal and irradiates the MMD 2 with the light beam LB. The MMD 2 rotates the mirror unit 20 along the first axis a based on the input drive signal. １ and the second axis a ２ Rock it around.

[0031] Although the details will be described later, for example, the drive control unit 4 rotates the mirror unit 20 along the first axis a １ and the second axis a ２ , and the light beam LB reflected by the mirror portion 20 is scanned so as to trace a Lissajous waveform on the surface to be scanned 5. This optical scanning method is called a Lissajous scanning method.

[0032] The optical scanning device 10 is applicable to, for example, a Lissajous scanning laser display. Specifically, the optical scanning device 10 is applicable to a laser scanning display such as an augmented reality (AR) glass or a virtual reality (VR) glass.

[0033] 2 shows an example of the hardware configuration of the drive control unit 4. The drive control unit 4 has a CPU (Central Processing Unit) 40, a ROM (Read Only Memory) 41, a RAM (Random Access Memory) 42, a light source driver 43, and an MMD driver 44. The CPU 40 is a computing device that realizes the overall function of the drive control unit 4 by reading programs and data from storage devices such as the ROM 41 into the RAM 42 and executing processing.

[0034] The ROM 41 is a non-volatile storage device that stores programs for the CPU 40 to execute processes and data such as the optical scanning information described above. The RAM 42 is a volatile storage device that temporarily stores programs and data.

[0035] The light source driver 43 is an electric circuit that outputs a drive signal to the light source 3 under the control of the CPU 40. In the light source driver 43, the drive signal is a drive voltage for controlling the irradiation timing and irradiation intensity of the light source 3.

[0036] The MMD driver 44 is an electric circuit that outputs a drive signal to the MMD 2 under the control of the CPU 40. In the MMD driver 44, the drive signal is a drive voltage for controlling the timing, period, and deflection angle of the oscillation of the mirror portion 20 of the MMD 2.

[0037] The CPU 40 controls the light source driver 43 and the MMD driver 44 based on the optical scanning information. The optical scanning information includes the scanning pattern of the light beam LB that scans the surface 5 to be scanned and the light emission timing of the light source 3.

[0038] Next, the configuration of the MMD 2 according to the embodiment will be described with reference to FIGS. 3 to 5. FIG. 3 is a plan view of the MMD 2 as seen from the light incident side. FIG. 4 is a cross-sectional view taken along line AA in FIG. 3. FIG. 5 is a cross-sectional view of the MMD 2 as seen from the light incident side. １ The figure shows the state in which the lens has rotated around the center.

[0039] 3, the MMD 2 has a mirror section 20, a pair of first support sections 21, a pair of movable frames 22, a pair of second support sections 23, a first actuator 24, a second actuator 25, a pair of first connection sections 26A, a pair of second connection sections 26B, and a fixed frame 27. The MMD 2 is a so-called MEMS scanner.

[0040] The mirror section 20 has a reflecting surface 20A that reflects incident light. The reflecting surface 20A is formed of a thin metal film such as gold (Au) or aluminum (Al) provided on one surface of the mirror section 20. The shape of the reflecting surface 20A is, for example, a first axis a １ and the second axis a ２ It is a circle with the intersection point of

[0041] 1st axis a １ and the second axis a ２ For example, when the mirror unit 20 is stationary, the first axis a is present in a plane including the reflecting surface 20A. １and is symmetrical about the second axis a ２ It is symmetrical about the center.

[0042] The pair of first support portions 21 are ２ and the second axis a ２ Each of the first support portions 21 has a shape that is line-symmetrical about the first axis a. １ Each of the first support portions 21 has a shape that is line-symmetrical about the first axis a １ The mirror section 20 is connected to the first axis a １ It is supported so that it can swing around.

[0043] The pair of movable frames 22 are arranged along a first axis a １ and are arranged at positions facing each other across the first axis a １ Each of the movable frames 22 has a shape that is line-symmetrical about the second axis a ２ The movable frames 22 are shaped to be line-symmetrical about the center. Each movable frame 22 is curved along the outer periphery of the mirror section 20. Both ends of the movable frame 22 are connected to the first support section 21.

[0044] The pair of first support parts 21 and the pair of movable frames 22 are connected to each other to surround the mirror part 20. The mirror part 20, the pair of first support parts 21, and the pair of movable frames 22 constitute the movable part 50.

[0045] The pair of second support portions 23 are １ and are arranged at positions facing each other across the first axis a １ Each of the second support portions 23 has a shape that is line-symmetrical about the second axis a ２ Each of the second support portions 23 has a shape that is line-symmetrical about the second axis a ２ The movable portion 50 having the mirror portion 20 is connected to the movable frame 22 on the second axis a. ２ Both ends of each of the second support portions 23 are connected to a first actuator 24.

[0046] The first actuator 24 is ２The piezoelectric element 24A is configured by a pair of first piezoelectric elements 24A facing each other with the second axis a ２ The first actuator 24 has a shape that is symmetrical about the first axis a. １ The first actuator 24 is disposed along the outer periphery of the pair of movable frames 22 and the pair of first support portions 21. The first actuator 24 is a piezoelectric drive type actuator.

[0047] In FIG. 3, the first piezoelectric element 24A constituting the first actuator 24 is aligned along the first axis a １ It appears to be separated by the first axis a １ The two first piezoelectric elements 24A facing each other with the first piezoelectric element 24A sandwiched therebetween are electrically connected by metal wiring (not shown).

[0048] The pair of second support portions 23 and the first actuator 24 are connected to each other, thereby surrounding the movable portion 50 .

[0049] The second actuator 25 is １ The piezoelectric element 25A is configured by a pair of second piezoelectric elements 25A facing each other with the first axis a １ The second actuator 25 has a shape that is symmetrical about the second axis a. ２ The second actuator 25 is formed along the outer periphery of the first actuator 24 and the pair of second support portions 23. The second actuator 25 is a piezoelectric actuator.

[0050] In FIG. 3, the second piezoelectric element 25A constituting the second actuator 25 is ２ It appears to be separated by the second axis a ２ The two second piezoelectric elements 25A facing each other with the second piezoelectric element 25A sandwiched therebetween are electrically connected by metal wiring (not shown).

[0051] The pair of first connecting portions 26A are connected to the second axis a ２ and the second axis a ２ Each of the first connection portions 26A has a shape that is line-symmetrical about the first axis a. １Each of the first connection portions 26A has a shape that is line-symmetrical about the first axis a. １ and arranged along a first axis a １ Above, the first actuator 24 and the second actuator 25 are connected.

[0052] The second actuator 25 surrounds the pair of movable frames 22 and the first actuator 24. The pair of second support parts 23, the first actuator 24, and the second actuator 25 constitute a drive part that is arranged surrounding the pair of movable frames 22.

[0053] The pair of second connection portions 26B are connected to the first axis a １ The second connection portions 26B are arranged at positions facing each other with the second axis a ２ Each of the second connection portions 26B has a shape that is line-symmetrical about the second axis a ２ and arranged along the second axis a ２ The second actuator 25 and the fixed frame 27 are connected to each other by the pair of second connecting portions 26B. ２ It is supported so that it can swing around.

[0054] The fixed frame 27 is a frame-shaped member having a rectangular outer shape, and has a first axis a １ and the second axis a ２ The outer shape of the fixed frame 27 is symmetrical about the first axis a １ is parallel to the second axis a ２ Two opposing sides at the center and the second axis a ２ is parallel to the first axis a １ The fixed frame 27 surrounds the outer periphery of the pair of second actuators 25 and the second connection portion 26B. In other words, the fixed frame 27 is disposed to surround the drive portion.

[0055] The first actuator 24 is connected to the mirror unit 20 and the pair of movable frames 22 by a second axis a ２ By applying a rotational torque around the second axis a ２ The second actuator 25 rotates the mirror unit 20, the pair of movable frames 22, and the first actuator 24 around the first axis a. １By applying a rotational torque around the first axis a １ Swing it around.

[0056] Furthermore, in the mirror section 20, a plurality of slits 20B and 20C are formed on the outer side of the reflecting surface 20A along the outer periphery of the reflecting surface 20A. The plurality of slits 20B and 20C are aligned along the first axis a １ and the second axis a ２ The slits 20B and 20C are arranged at positions that are line-symmetrical with respect to the center of the mirror 20. The slits 20B and 20C have the effect of suppressing distortion that occurs in the reflecting surface 20A when the mirror portion 20 swings.

[0057] 3 does not show metal wiring and metal pads for applying drive signals to the first actuator 24 and the second actuator 25. A plurality of metal pads are provided on the fixed frame 27. The metal pads are also called electrode pads.

[0058] 4, the MMD 2 is formed, for example, by etching an SOI (Silicon On Insulator) substrate 30. The SOI substrate 30 is a substrate in which a silicon oxide layer 32 is provided on a silicon support layer 31 made of single crystal silicon, and a silicon active layer 33 made of single crystal silicon is provided on the silicon oxide layer 32.

[0059] The mirror portion 20, the pair of first support portions 21, the pair of movable frames 22, the pair of second support portions 23, the first actuator 24, the second actuator 25, the pair of first connection portions 26A, and the pair of second connection portions 26B are formed by removing the silicon support layer 31 and the silicon oxide layer 32 from the SOI substrate 30 by etching, and then patterning the remaining silicon active layer 33.

[0060] The fixed frame 27 is formed of three layers: a silicon support layer 31, a silicon oxide layer 32, and a silicon active layer 33. That is, the mirror section 20, the pair of first support sections 21, the pair of movable frames 22, the pair of second support sections 23, the first actuator 24, the second actuator 25, the pair of first connecting sections 26A, and the pair of second connecting sections 26B are each thinner than the fixed frame 27. In the present disclosure, thickness refers to the width in the Z direction.

[0061] The first piezoelectric element 24A and the second piezoelectric element 25A described above have a laminated structure in which a lower electrode, a piezoelectric film, and an upper electrode are laminated in this order on a silicon active layer 33.

[0062] The lower electrode and the upper electrode are made of a metal such as gold (Au) or platinum (Pt). The piezoelectric film is made of a piezoelectric material such as PZT (lead zirconate titanate). The lower electrode and the upper electrode are electrically connected to the drive control unit 4 via wiring and electrode pads.

[0063] The lower electrode is connected to the drive control unit 4 via wiring and an electrode pad, and is supplied with a ground potential. A drive voltage is applied from the drive control unit 4 to the upper electrode.

[0064] When a positive or negative voltage is applied to the piezoelectric film in the polarization direction, the piezoelectric film undergoes deformation (e.g., expansion and contraction) proportional to the applied voltage. In other words, the piezoelectric film exhibits the so-called inverse piezoelectric effect. When a drive voltage is applied to the upper electrode from the drive control unit 4, the piezoelectric film exhibits the inverse piezoelectric effect, displacing the first actuator 24 and the second actuator 25.

[0065] 5 shows a state in which one of the pair of second piezoelectric elements 25A constituting the second actuator 25 is expanded and the other is contracted, whereby the second actuator 25 is caused to move along the first axis a １ In this way, one of the pair of second piezoelectric elements 25A is displaced in the opposite directions, so that the mirror section 20 rotates around the first axis a. １ rotates around the

[0066] 5 shows an example in which the second actuator 25 is driven in an anti-phase resonance mode (hereinafter referred to as an anti-phase rotation mode) in which the displacement direction of the pair of piezoelectric actuators and the rotation direction of the mirror section 20 are opposite to each other. In contrast, an in-phase resonance mode in which the displacement direction of the pair of piezoelectric actuators and the rotation direction of the mirror section 20 are the same is called an in-phase rotation mode. In this embodiment, the second actuator 25 is driven in the anti-phase rotation mode.

[0067] The first axis a of the mirror section 20 １ The deflection angle θ is controlled by a drive signal (hereinafter referred to as a first drive signal) that the drive control unit 4 provides to the second actuator 25. The first drive signal is, for example, a sinusoidal AC voltage. The first drive signal is a drive voltage waveform V applied to one of the pair of piezoelectric actuators. １Ａ (t) and the driving voltage waveform V applied to the other １Ｂ (t) and the driving voltage waveform V １Ａ (t) and the driving voltage waveform V １Ｂ (t) are in opposite phase to each other (i.e., a phase difference of 180°).

[0068] The first axis a of the mirror part 20 １ The deflection angle θ corresponds to the angle at which the normal N of the reflecting surface 20A is tilted with respect to the Z direction in the YZ plane.

[0069] The first actuator 24 is driven in an anti-phase resonance mode in the same manner as the second actuator 25. ２ The deflection angle around the piezoelectric actuator 24 is controlled by a drive signal (hereinafter referred to as a second drive signal) that the drive control unit 4 supplies to the first actuator 24. The second drive signal is, for example, a sinusoidal AC voltage. The second drive signal is a drive voltage waveform V ２Ａ (t) and the driving voltage waveform V applied to the other ２Ｂ (t) and the driving voltage waveform V ２Ａ (t) and the driving voltage waveform V ２Ｂ (t) are in opposite phase to each other (i.e., a phase difference of 180°).

[0070] 6A and 6B show examples of the first and second drive signals. Fig. 6A shows a drive voltage waveform V １Ａ (t) and V １Ｂ FIG. 6B shows the drive voltage waveform V ２Ａ (t) and V ２Ｂ (t) is shown.

[0071] Drive voltage waveform V １Ａ (t) and V １Ｂ (t) are expressed as follows: V １Ａ (t) = V ｏｆｆ１ +V １ sin(2πf ｄ１ t) V １Ｂ (t) = V ｏｆｆ１ +V １ sin(2πf ｄ１ t + α)

[0072] Here, V １ is the amplitude voltage. V ｏｆｆ１ is the bias voltage. ｄ１ is the drive frequency (hereinafter referred to as the first drive frequency), t is time, and α is the drive voltage waveform V １Ａ (t) and V １Ｂ In this embodiment, for example, α=180°.

[0073] Drive voltage waveform V １Ａ (t) and V １Ｂ When the second actuator 25 is applied with the first drive frequency f ｄ１ The first axis a １ Swinging around.

[0074] Drive voltage waveform V ２Ａ (t) and V ２Ｂ (t) are expressed as follows: V ２Ａ (t) = V ｏｆｆ２ +V ２ sin(2πf ｄ２ t+φ) V ２Ｂ (t) = V ｏｆｆ２ +V ２ sin(2πf ｄ２ t + β + φ)

[0075] Here, V ２ is the amplitude voltage. V ｏｆｆ２ is the bias voltage. ｄ２ is the drive frequency (hereinafter referred to as the second drive frequency). t is time. β is the drive voltage waveform V ２Ａ (t) and V ２Ｂ In this embodiment, for example, β is set to 180°. φ is the phase difference of the driving voltage waveform V １Ａ (t) and V １Ｂ (t) and the driving voltage waveform V ２Ａ (t) and V ２Ｂ (t) is the phase difference with respect to (t).

[0076] In this embodiment, V ｏｆｆ１ ≧V １ and V ｏｆｆ２ ≧V ２ That is, the first drive signal and the second drive signal are set to positive voltages.

[0077] Drive voltage waveform V ２Ａ (t) and V ２Ｂ When the first actuator 24 is applied with the second drive frequency f ｄ２ and the second axis a ２ Swinging around.

[0078] First drive frequency f ｄ１ is the first axis a of the mirror part 20 １ The second drive frequency f is set to match the surrounding resonant frequency. ｄ２ is the second axis a of the mirror part 20 ２ In this embodiment, the first driving frequency f ｄ１ is the second driving frequency f ｄ２ Greater than.

[0079] 7 shows an example of a support substrate 70. The support substrate 70 is, for example, a ceramic PCB using ceramic as a base material. The planar shape of the support substrate 70 is, for example, an octagon formed by cutting out the four corners of a rectangle having a side length L1 in the X direction and a side length L2 in the Y direction. The thickness of the support substrate 70 is uniform. For example, L1 = 35 mm, L2 = 32 mm, and the thickness is 2 mm.

[0080] It is preferable that the lengths L1 and L2 satisfy the relationship L1>L2. ２ The moment of inertia around the first axis a １ By making the moment of inertia larger than that of the surroundings, the mirror part 20 is ２ It is preferable to suppress displacement of the support substrate 70 when it is swung around.

[0081] Region R in the center of the support substrate 70 is a fixing region where a package 60 housing an MMD 2 is fixed. Two screw holes 71 are provided in the support substrate 70. The two screw holes 71 are arranged at positions facing each other in the Y direction with the fixing region R as the center. Each of the two screw holes 71 has a spiral groove formed therein that allows a screw 72, described below, to be threaded therein. Each of the two screw holes 71 is an example of an external mounting portion for mounting the support substrate 70 to a base substrate 80. The distance L3 between the two screw holes 71 is, for example, 25 mm. For example, the base substrate 80 is made of aluminum. The base substrate 80 is an example of an "object to be mounted" according to the technology of the present disclosure.

[0082] Fig. 8 shows a state in which the support substrate 70 is attached to the base substrate 80. Fig. 9 is a cross-sectional view taken along line BB in Fig. 8.

[0083] The package 60 is made of, for example, ceramic and has an open top. The MMD 2 is fixed to the inner bottom surface of the package 60 and is electrically connected to the package 60 by wire bonding. A transparent glass lid 61 is attached to the opening of the package 60. The light beam LB described above is incident on the mirror portion 20 of the MMD 2 through the lid 61. The light beam LB reflected by the mirror portion 20 is emitted to the outside through the lid 61.

[0084] The package 60 is fixed to a fixing region R of the support substrate 70 via an adhesive or the like. The MMD 2, the package 60, and the lid 61 are an example of a "vibrator" according to the technology of the present disclosure. In other words, the support substrate 70 is a support substrate that supports the vibrator. Furthermore, the vibrator and the support substrate constitute a "module" according to the technology of the present disclosure.

[0085] The support substrate 70 is fixed to the base substrate 80 by screws 72 inserted into two screw holes 71. The screws 72 are made of, for example, polycarbonate.

[0086] The two screw holes 71 are used to fix the mirror part 20 of the MMD 2 to the first axis a １ When it is swung around the second axis a ２ The vibration nodes are provided in regions that become vibration nodes in both cases where the vibration is oscillated around the center of the shaft and where the vibration is oscillated around the center of the shaft. A vibration node is a region where the displacement in the Z direction becomes zero during vibration. In the present disclosure, a zero displacement refers to a region where the displacement is less than 0.02 mm from the stationary state.

[0087] FIG. 10 shows the mirror unit 20 along the first axis a １ The figure shows the results of a simulation of the displacement of the support substrate 70 when it is oscillated around the substrate in a specified vibration mode. ｄ１ = 28 kHz, and the first axis a １ The mirror section 20 was swung so that the maximum deflection angle around the circumference was 7.5° (i.e., the total optical angle was 30°). In this simulation, the support substrate 70 was not fixed to the base substrate 80.

[0088] As shown in FIG. 10, the mirror unit 20 is １ When the support substrate 70 is swung around the first axis a, the support substrate 70 is divided into five regions A1 to A5 based on the displacement in the Z direction. The region A1 is a region where the displacement is zero and serves as a node of vibration. １ and is formed to include areas A4 and A5. Area A1 corresponds to the "first area" according to the technology of the present disclosure.

[0089] The regions A2 to A5 are regions where the displacement amount is not zero. The region A2 is formed on the +Y direction side of the region A1. The region A3 is formed on the −Y direction side of the region A1. The regions A2 and A3 are located on the first axis a １ The displacement direction of the region A2 is opposite to the displacement direction of the region A3. For example, when the displacement direction of the region A2 is the +Z direction, the displacement direction of the region A3 is the −Y direction.

[0090] The area A4 is the first axis a １ The area A5 is formed between the first axis a and the screw hole 71 on the positive side. １ The area A4 and the area A5 are formed between the first axis a １ The displacement direction of the region A4 is opposite to that of the region A5. For example, if the displacement direction of the region A4 is the −Z direction, the displacement direction of the region A5 is the +Y direction.

[0091] Furthermore, the displacement direction of region A2 and the displacement direction of region A4 are opposite to each other. For example, if the displacement direction of region A2 is the +Z direction, the displacement direction of region A4 is the -Y direction. Furthermore, the displacement direction of region A3 and the displacement direction of region A5 are opposite to each other. For example, if the displacement direction of region A3 is the -Z direction, the displacement direction of region A5 is the +Y direction.

[0092] FIG. 11 shows the mirror section 20 along the second axis a ２ 10 shows the results of a simulation of the displacement of the support substrate 70 when it is swung around the substrate. ｄ２ = 14 kHz, and the second axis a ２ The mirror section 20 was swung so that the maximum deflection angle around the circumference was 7.5° (i.e., the total optical angle was 30°). In this simulation, the support substrate 70 was not fixed to the base substrate 80.

[0093] As shown in FIG. 11, the mirror portion 20 is ２ When the support substrate 70 is swung around the second axis a, the support substrate 70 is divided into three regions B1 to B3 based on the displacement in the Z direction. Region B1 is a region where the displacement is zero and serves as a node of vibration. Region B1 is a region where the displacement is zero and serves as a node of vibration.２ The region B1 corresponds to the "second region" according to the technology of the present disclosure.

[0094] The region B2 is formed on the +X direction side of the region B1. The region B3 is formed on the −X direction side of the region B1. The regions B2 and B3 are arranged on the second axis a ２ The shape is symmetrical across the center.

[0095] As shown in FIGS. 10 and 11, the two screw holes 71 are provided to fix the mirror unit 20 to the first axis a １ When the mirror part 20 is swung around the second axis a, an area A1 becomes a node of vibration. ２ The mirror section 20 is arranged in a region where the vibration node B1 overlaps with the region B2, which becomes the node of the vibration when the mirror section 20 is oscillated around the first axis a. Therefore, when the support substrate 70 is fixed to the base substrate 80, the vibration caused by the vibrating body is prevented from propagating to the base substrate 80. Specifically, when the mirror section 20 is oscillated around the first axis a １ Circumference and second axis a ２ Even when the supporting substrate 70 and the surrounding area are oscillated simultaneously, the area where the two screw holes 71 are located is a vibration node area and the amount of displacement is zero, so the propagation of vibration from the supporting substrate 70 to the base substrate 80 is suppressed.

[0096] 12 will explain in more detail the arrangement of the two screw holes 71. As shown in FIG. 12, the mirror unit 20 is aligned along the first axis a １ When the vibrating body is oscillated in a specified vibration mode, the vibration node A1 (see FIG. 10) has a pair of non-parallel regions A1b that do not extend parallel to the linear region C where the displacement of the vibrating body is zero, in addition to a parallel region A1a that extends parallel to the linear region C where the displacement of the vibrating body is zero. The linear region C is formed between the above-mentioned region A4 and region A5. The parallel region A1a is formed along the first axis a. １ In other words, the parallel region A1a is a region including the first axis a １ It is an area having a predetermined width in the Y direction based on the reference.

[0097] The two screw holes 71 are arranged in a pair of non-parallel areas A1b. In this manner, the support substrate 70 of this embodiment supports the mirror unit 20 along the first axis a １12, each of the non-parallel regions A1b is horseshoe-shaped. By providing a screw hole 71 in each of the non-parallel regions A1b and fixing the support substrate 70 to the base substrate 80, the propagation of vibration can be effectively suppressed.

[0098] 13 illustrates a vibration simulation using the support substrate 70. The non-parallel region A1b can be identified by the following method using the results of the vibration simulation using the support substrate 70.

[0099] First, as shown in FIG. １ The first axis a is fixed to the fixing region R for fixing the vibrating body of the support substrate 70 so that a displacement having a common spatial symmetry with the surrounding vibration modes occurs. １ The torque is applied with the oscillation axis at the first axis a. １ is the axis of symmetry, and the first axis a １ This is a symmetry in which the direction of displacement is opposite on one side and the other side.

[0100] Next, the torque frequency ω is swept to identify the resonance modes occurring in the support substrate 70. Fig. 14 is a contour diagram showing an example of the resonance modes occurring in the support substrate 70.

[0101] The resonance frequency of the n-th resonance mode among the resonance modes is defined as ω ｎ The maximum displacement in the Z direction at the coordinates (X, Y) of the support substrate 70 in the n-th resonance mode is Z ｎ When (X, Y) is taken as the coordinate system, the integrated displacement amount Z is expressed by the following equation (1): ｍ Calculate (X, Y).

[0102]

[0103] where ω ｍ is the first axis a １ The frequency of the vibration mode around, for example, ω ｍ = f ｄ１ is.

[0104] The cumulative displacement Z calculated by the above formula (1)ｍ The distribution of (X, Y) is calculated by moving the vibrator at a frequency ω ｍ 15 shows the distribution of the displacement of the support substrate 70 when the vibrator is driven at a frequency ω ｍ 10 is a contour diagram showing an example of the displacement of the support substrate 70 when driven at .

[0105] Therefore, Z ｍ The region A1, which is the node of the vibration, can be determined by determining the region where (X, Y) = 0. Furthermore, from the region A1, a non-parallel region A1b, which does not extend parallel to the linear region C where the displacement of the vibrating body is zero, can be identified.

[0106] As described above, the non-parallel region A1b can be identified by a vibration simulation using the support substrate 70. However, the non-parallel region A1b may not exist depending on the planar shape and thickness of the support substrate 70. For this reason, it is preferable to identify the planar shape and thickness of the support substrate 70 in which the non-parallel region A1b exists by a vibration simulation.

[0107] In this embodiment, the mirror unit 20 is aligned along the first axis a １ When the support substrate 70 is swung around the first axis a １ The vibration occurs along the first axis a, not along the node of vibration. １ The second axis a is perpendicular to ２ The MMD2 is characterized by having an external mounting part at the node of vibration generated on the first axis a. １ It may also be a one-axis mirror device in which the mirror portion 20 swings only around the center.

[0108] Second Embodiment Next, a second embodiment of the present disclosure will be described. The optical scanning device 10 according to the second embodiment has the same configuration as the first embodiment, except that it has a support substrate 70A that is different in shape from the support substrate 70 of the first embodiment.

[0109] 16 shows a support substrate 70A according to the second embodiment. The support substrate 70A has a rectangular shape with a side length in the X direction of L1 and a side length in the Y direction of L2, formed by cutting out both sides of the rectangular shape. The support substrate 70A has a uniform thickness. For example, L1 = 23 mm, L2 = 28 mm, and the thickness is 1.5 mm.

[0110] As in the first embodiment, the support substrate 70A has two screw holes 71 at positions facing each other in the Y direction, centered on the fixing region R where the package 60 is fixed. The distance L3 between the two screw holes 71 is, for example, 21 mm. The support substrate 70A is fixed to the base substrate 80 by screws 72 inserted into each of the two screw holes 71.

[0111] FIG. 17 shows the mirror unit 20 along the first axis a １ 10 shows the results of a simulation of the displacement of the support substrate 70A when it is oscillated around the substrate 70A in a specified vibration mode. ｄ１ = 28 kHz, and the first axis a １ The mirror section 20 was swung so that the maximum deflection angle around the circumference was 7.5° (i.e., the total optical angle was 30°). Note that in this simulation, the support substrate 70A was not fixed to the base substrate 80.

[0112] 17, in this embodiment, the support substrate 70A is also divided into five regions A1 to A5. Region A1 is further divided into a parallel region A1a and a pair of non-parallel regions A1b. In this embodiment, too, two screw holes 71 are located in the pair of non-parallel regions A1b.

[0113] FIG. 18 shows the mirror section 20 along the second axis a ２ 10 shows the results of a simulation of the displacement of the support substrate 70A when it is swung around the substrate. ｄ２ = 14 kHz, and the second axis a ２ The mirror section 20 was swung so that the maximum deflection angle around the circumference was 7.5° (i.e., the total optical angle was 30°). Note that in this simulation, the support substrate 70A was not fixed to the base substrate 80.

[0114] 18, the support substrate 70A is also divided into three regions B1 to B3 in this embodiment. １ When the mirror part 20 is swung around the second axis a, an area A1 becomes a node of vibration. ２ The vibrating body is disposed in a region that overlaps with region B1, which becomes a node of vibration when the vibrating body is swung around the support substrate 70A. Therefore, when the support substrate 70A is fixed to the base substrate 80, the vibration caused by the vibrating body is prevented from propagating to the base substrate 80.

[0115] Comparative Example Next, a comparative example will be described. The optical scanning device 10 according to the comparative example has the same configuration as that of the first embodiment, except that it has a support substrate 70B that is different in shape from the support substrate 70 of the first embodiment.

[0116] 19 shows a support substrate 70B according to a comparative example. The support substrate 70B is a hexagon formed by cutting out the four corners of a rectangle having sides of length L1 in the X direction and sides of length L2 in the Y direction. The support substrate 70B has a uniform thickness. For example, L1 = 13 mm, L2 = 28 mm, and the thickness is 1.6 mm.

[0117] As in the first embodiment, the support substrate 70B has two screw holes 71 at positions facing each other in the Y direction, centered on the fixing region R where the package 60 is fixed. The distance L3 between the two screw holes 71 is, for example, 18 mm. The support substrate 70B is fixed to the base substrate 80 by screws 72 inserted into each of the two screw holes 71.

[0118] FIG. 20 shows the mirror unit 20 along the first axis a １ 10 shows the results of a simulation of the displacement of the support substrate 70B when it is oscillated around the substrate 70B in a specified vibration mode. ｄ１ = 28 kHz, and the first axis a １ The mirror section 20 was swung so that the maximum deflection angle around the circumference was 7.5° (i.e., the total optical angle was 30°). Note that in this simulation, the support substrate 70B was not fixed to the base substrate 80.

[0119] 20, in this comparative example, the support substrate 70B is divided into three regions A1 to A3. In this comparative example, region A1 is a region that becomes a node of vibration, but all of region A1 is a parallel region that extends parallel to a linear region where the displacement of the vibrating body is zero, and does not include a non-parallel region.

[0120] Region A2 is formed on the +Y direction side of region A1. Region A3 is formed on the −Y direction side of region A1. The displacement directions of region A2 and region A3 are opposite to each other. In this comparative example, one of the two screw holes 71 is located in region A2, and the other is located in region A3.

[0121] FIG. 21 shows the mirror section 20 along the second axis a ２ 10 shows the results of a simulation of the displacement of the support substrate 70B when it is swung around the substrate 70B. ｄ２ = 14 kHz, and the second axis a ２ The mirror section 20 was swung so that the maximum deflection angle around the circumference was 7.5° (i.e., the total optical angle was 30°). Note that in this simulation, the support substrate 70B was not fixed to the base substrate 80.

[0122] 21, the support substrate 70B is also divided into three regions B1 to B3 in this comparative example. In this comparative example, the two screw holes 71 are provided to align the mirror section 20 with the first axis a １ When the mirror part 20 is swung around the second axis a, an area A1 becomes a node of vibration. ２ The vibrating body is not disposed in a region that overlaps with region B1, which becomes a node of vibration when the vibrating body is swung around the vibrating body. Therefore, when the support substrate 70B is fixed to the base substrate 80, it is not possible to prevent the vibration caused by the vibrating body from propagating to the base substrate 80.

[0123] 22 shows the results of a simulation of the maximum displacement of the base substrate when the support substrates 70, 70A, and 70B according to the comparative example, the first embodiment, and the second embodiment are fixed to the base substrate 80. In this simulation, f ｄ１ = 28 kHz, and the first axis a １The maximum displacement of the base substrate 80 in the Z direction was evaluated when the mirror section 20 was swung so that the maximum value of the deflection angle around the circumference was 7.5° (i.e., the total optical angle was 30°).

[0124] According to FIG. 22, in the first and second embodiments, the maximum displacement of the base substrate 80 is suppressed more than in the comparative example, that is, the propagation of vibrations caused by the vibrating body to the base substrate 80 is suppressed.

[0125] [Modifications] Various modifications of the above embodiments will be described below.

[0126] In each of the above embodiments, the external attachment portion is a screw hole having a groove formed therein for threading a screw, but the external attachment portion may be a through hole having no groove and capable of threading a screw. Furthermore, the external attachment portion is not limited to a screw hole or a through hole as long as it enables the support substrate to be attached to an external attachment object. Furthermore, the attachment object is not limited to a base substrate.

[0127] Furthermore, in each of the above embodiments, the MMD 2 is a two-axis mirror device in which the mirror portion oscillates around two intersecting axes, but the MMD 2 may also be a one-axis mirror device in which the mirror portion oscillates around one axis.

[0128] Furthermore, in each of the above embodiments, the hardware configuration of the drive control unit 4 can be modified in various ways. The processing unit of the drive control unit 4 may be configured with a single processor, or may be configured with a combination of two or more processors of the same or different types. Processors include CPUs, programmable logic devices (PLDs), dedicated electrical circuits, etc. As is well known, a CPU is a general-purpose processor that executes software (programs) to function as various processing units. A PLD is a processor, such as an FPGA (Field Programmable Gate Array), whose circuit configuration can be changed after manufacturing. A dedicated electrical circuit is a processor, such as an ASIC (Application Specific Integrated Circuit), that has a circuit configuration designed specifically to execute specific processing.

[0129] The following techniques can be understood from the above description. [Supplementary Item 1] A support substrate that supports a vibrating body, wherein when the vibrating body is driven in a specified vibration mode, a region that becomes a node of vibration includes a pair of non-parallel regions that do not extend parallel to a linear region in the vibrating body where the displacement amount is zero, and each of the pair of non-parallel regions is provided with an external attachment portion for attachment to an external object. [Supplementary Item 2] The support substrate according to Supplementary Item 1, wherein the external attachment portion is a screw hole or a through-hole. [Supplementary Item 3] The support substrate according to Supplementary Item 1 or Supplementary Item 2, wherein the external attachment portions are arranged at positions that face each other with respect to a fixing region to which the vibrating body is fixed. [Supplementary Item 4] The pair of non-parallel regions are configured to set a resonance frequency of an n-th resonance mode of a group of resonance modes that occurs when the fixing region to which the vibrating body is fixed is driven by applying a torque so as to generate a displacement that has a common spatial symmetry with the vibration mode. ｎ The maximum displacement in the Z direction at the coordinates (X, Y) is Z ｎ (X, Y), and the frequency of the vibration mode is ω ｍ In this case, Z represented by the following formula (1) ｍThe supporting substrate according to any one of Supplementary Items 1 to 3, which is included in a region where (X, Y) is zero. [Supplementary Item 5] A module including: a support substrate according to any one of Supplementary Items 1 to 4; and the vibrating body supported by the support substrate. [Supplementary Item 6] The module according to Supplementary Item 5, wherein the vibrating body includes a mirror device and a package accommodating the mirror device, and the mirror device includes: a movable part including a mirror portion that reflects incident light; and a drive part connected to the movable part and swinging the mirror portion around at least one swing axis. [Supplementary Item 7] The module according to Supplementary Item 6, wherein the vibration mode occurs when the mirror portion swings around the swing axis. [Supplementary Item 8] The module according to Supplementary Item 7, wherein the movable part includes: a pair of first support parts connected to the mirror portion and arranged on a first axis; and a pair of movable frames connected to the pair of first support parts and facing each other across the first axis, and the swing axis is the first axis. [Supplementary Item 9] The module according to Supplementary Item 8, wherein the drive unit comprises: a pair of second support parts connected to the movable frame on a second axis intersecting the first axis and supporting the movable unit, the pair of second support parts being arranged on the second axis. [Supplementary Item 10] The module according to Supplementary Item 9, wherein the external mounting part is arranged in a region where a first region that becomes a node of vibration when the mirror unit is swung about the first axis and a second region that becomes a node of vibration when the mirror unit is swung about the second axis overlap, the pair of non-parallel regions being included in the first region. [Supplementary Item 11] The module according to Supplementary Item 10, wherein the drive unit includes a first actuator connected to the pair of second support parts and having a pair of first piezoelectric elements facing each other across the second axis. [Supplementary Item 12] The module according to Supplementary Item 11, wherein the drive unit includes a second actuator that is arranged to surround the first actuator and has a pair of second piezoelectric elements facing each other across the first axis.[Supplementary Item 13] An optical scanning device comprising: a support substrate according to any one of Supplementary Items 1 to 4; the vibrator supported by the support substrate; and a processor that drives the vibrator, wherein the vibrator includes a mirror device including a mirror portion that reflects incident light and a package that houses the mirror device, and the mirror device includes a drive portion that oscillates the mirror portion in response to a drive signal provided from the processor.

Claims

1. A support substrate that supports a vibrating body, wherein when the vibrating body is driven in a specified vibration mode, a region that becomes a vibration node includes a pair of non-parallel regions that do not extend parallel to a linear region in the vibrating body where the displacement amount is zero, and an external attachment part is provided on each of the pair of non-parallel regions for attachment to an external attachment object.

2. The support substrate according to claim 1, wherein the external mounting portion is a screw hole or a through hole.

3. The support substrate according to claim 1, wherein the external mounting portions are arranged at positions facing each other with the fixing area where the vibrating body is fixed as the center.

4. The pair of non-parallel regions has a resonance frequency of ω in the n-th resonance mode among the resonance modes that occur when the vibrating body is driven by applying torque so that a displacement having a common spatial symmetry with the vibration mode occurs in the fixed region to which the vibrating body is fixed. ｎ The maximum displacement in the Z direction at the coordinates (X, Y) is Z ｎ (X, Y), and the frequency of the vibration mode is ω ｍ In this case, Z represented by the following formula (1) ｍ The support substrate according to claim 1 , which is included in a region where (X, Y) is zero.

5. A module comprising: a support substrate according to any one of claims 1 to 4; and a vibrating body supported by the support substrate.

6. The module according to claim 5, wherein the vibrating body includes a mirror device and a package that houses the mirror device, and the mirror device includes a movable part that includes a mirror portion that reflects incident light, and a drive part that is connected to the movable part and that causes the mirror portion to oscillate around at least one oscillation axis.

7. The module according to claim 6, wherein the vibration mode occurs when the mirror section is oscillated around the oscillation axis.

8. The module described in claim 7, wherein the movable section comprises: a pair of first support sections connected to the mirror section and arranged on a first axis; and a pair of movable frames connected to the pair of first support sections and facing each other across the first axis, and the oscillation axis is the first axis.

9. The module described in claim 8, wherein the drive unit is connected to the movable frame on a second axis intersecting the first axis and comprises a pair of second support parts that support the movable unit, and the pair of second support parts are arranged on the second axis.

10. The module described in claim 9, wherein the external mounting portion is arranged in a region where a first region that becomes a node of vibration when the mirror portion is oscillated around the first axis and a second region that becomes a node of vibration when the mirror portion is oscillated around the second axis overlap, and the pair of non-parallel regions are included in the first region.

11. The module according to claim 10, wherein the driving section includes a first actuator connected to a pair of the second support sections and having a pair of first piezoelectric elements facing each other across the second axis.

12. The module according to claim 11, wherein the driving section includes a second actuator having a pair of second piezoelectric elements arranged to surround the first actuator and facing each other across the first axis.

13. An optical scanning device comprising: a support substrate according to any one of claims 1 to 4; a vibrating body supported on said support substrate; and a processor for driving said vibrating body, wherein said vibrating body is configured to include a mirror device including a mirror portion that reflects incident light and a package that houses said mirror device, and said mirror device includes a drive portion that oscillates said mirror portion in response to a drive signal provided by said processor.

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