Light deflection device

Abstract

To provide an optical deflection device that can suppress stray light.SOLUTION: An optical deflection device (50) includes: a movable member (121) for deflecting an incident light (Li) from a light emitting unit; and a lid member (52) covering the movable member (121). The lid member (52) includes: an opening unit (521) for allowing the incident light (Li) and a deflected light (Lo) deflected by the movable member (121) to pass through; and an optical attenuation unit (100) for attenuating the incident light (Li) or the deflected light (Lo) reflected by the lid member (52).SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to an optical deflection device.

Background Art

[0002] Conventionally, an optical deflection device having a movable member that deflects incident light from a light emitting portion has been known.

[0003] Also, an optical deflection device having a lid member that covers a movable member and having a root mean square roughness of a surface constituting a recess provided in the lid member of 15 nm or less has been disclosed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An opening for allowing incident light from a light emitting portion and deflected light of the incident light by the movable member to pass through is provided in a lid member that covers the movable member. However, in order to reduce disturbance light that enters from the outside to the inside of the optical deflection device, it is preferable that the opening width of the opening is as small as possible. However, when the opening width of the opening is reduced, there is a concern that stray light, which is unintended light, is generated by reflection of a part of the incident light from the light emitting portion or the deflected light of the incident light by the movable member by the front surface or the back surface of the lid member around the opening, or the inner surface of the opening.

[0006] An object of the present invention is to provide an optical deflection device capable of suppressing stray light.

Means for Solving the Problems

[0007] An optical deflection device (50) according to an aspect of the present invention deflects incident light (Li) from a light emitting portionIn two directions orthogonal to each other It has a movable member (121) for causing deflection and a lid member (52) for covering the movable member (121). The lid member (52) has an opening (521) for allowing incident light (Li) and deflected light (Lo) deflected by the movable member (121) of the incident light (Li) to pass through, and on the lid member (52) in incident light (Li) reflection of or deflected light (Lo) reflection of and reduce a light attenuation part (100). The light attenuation part (100) is provided on at least a part of at least one of the surface of the lid member (52) on the side of the movable member (121), the surface of the movable member (121) opposite to the movable member (121), or the inner surface (523) of the opening (521). The opening (521) includes a first opening (521i) through which incident light (Li) passes and a second opening (521o) through which deflected light (Lo) passes. When viewed from a direction orthogonal to each of the two directions, in the direction orthogonal to the direction in which the incident light (Li) is incident, the opening width of the second opening (521o) is larger than the opening width of the first opening (521i). .

[0008] Note that the reference numerals in the parentheses above are attached for ease of understanding and are merely examples, and are not limited to the illustrated embodiments.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide an optical deflection device capable of suppressing stray light.

Brief Description of the Drawings

[0010]

Figure 1

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Figure 5B

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Figure 7A

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Figure 10

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Figure 23

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments for implementing the invention will be described with reference to the drawings. In each drawing, the same reference numerals are assigned to the same components, and redundant descriptions may be omitted.

[0012] The embodiments shown below illustrate an optical deflection device for embodying the technical idea of the present invention, and the present invention is not limited to the embodiments shown below. Dimensions, materials, shapes, relative arrangements, etc. of the components described below are not intended to limit the scope of the present invention only to those, but are intended to be illustrative unless otherwise specified. Also, the sizes and positional relationships of the members shown in the drawings may be exaggerated for clarity of explanation.

[0013] In the figures shown below, the directions may be indicated by the X-axis, Y-axis, and Z-axis. The X-direction along the X-axis and the Y-direction along the Y-axis indicate two directions that are substantially orthogonal to the direction in which the movable member included in the optical deflection device according to the embodiment deflects light. The Z-direction along the Z-axis indicates a direction that is substantially orthogonal to both the X-axis and the Y-axis.

[0014] Also, the direction in which the arrow points in the X-direction is denoted as the +X direction, the opposite direction of the +X direction is denoted as the -X direction, the direction in which the arrow points in the Y-direction is denoted as the +Y direction, the opposite direction of the +Y direction is denoted as the -Y direction, the direction in which the arrow points in the Z-direction is denoted as the +Z direction, and the opposite direction of the +Z direction is denoted as the -Z direction. However, these do not limit the orientation during the use of the optical deflection device, and the optical deflection device can be arranged in any orientation.

[0015] [Embodiment] <Example of the overall configuration of the optical deflection device 50> With reference to FIGS. 1 and 2, the overall configuration of the optical deflection device 50 according to the embodiment will be described. FIG. 1 is a perspective view illustrating the overall configuration of the optical deflection device 50, and FIG. 2 is a perspective view showing a state in which the light transmission plate 53 is removed from the optical deflection device 50.

[0016] As shown in FIGS. 1 and 2, the optical deflection device 50 includes a package 51 and a lid 52. The lid 52 is provided on the +Z direction side of the package 51. The lid 52 has an opening 521 which is a through hole. Also, an optical transmission plate 53 is provided on the +Z direction side of the lid 52.

[0017] The optical deflection device 50 deflects a laser beam emitted by a light emitting part provided outside the optical deflection device 50, passing through the optical transmission plate 53 and then passing through the opening 521 of the lid 52, by an optical deflection part provided in the package 51. The light emitting part is, for example, a semiconductor laser. The light emitting part may include a plurality of semiconductor lasers having different wavelengths of the emitted laser beams.

[0018] The deflection of light means changing the traveling direction of light such as a laser beam. The optical deflection part according to the embodiment deflects the laser beam by reflecting it with a reflecting surface. The configuration of the optical deflection part will be described in detail separately with reference to FIGS. 3 and 4.

[0019] The package 51 is a box-shaped member that holds the optical deflection part inside. The package 51 is composed of, for example, alumina ceramics, a metal material such as aluminum, an aluminum alloy or stainless steel, or a plastic material. The package 51 includes a circuit board or the like made of FRP (Fiber Reinforced Plastics) or FPC (Flexible printed circuits).

[0020] The lid 52 is an example of a lid member that covers a movable member included in the optical deflection part. The lid 52 holds the optical transmission plate 53 and plays a role of reducing external light that enters from the outside to the inside of the optical deflection device 50.

[0021] The lid 52 is composed of a material such as alumina ceramics, aluminum, aluminum alloy, stainless steel, or plastic that is not translucent to the laser beam emitted by the light emitting part, and is a box-shaped member with a substantially square shape in plan view when viewed from the Z-direction side. The lid 52 is fixed by an adhesive member or the like in a state where the end portion on the -Z direction side is in contact with the mounting surface 511 provided on the +Z direction side of the package 51.

[0022] The end portion on the +Z direction side of the lid 52 is formed to be inclined with respect to the mounting surface 511. The lid 52 fixes and holds the light transmission plate 53 on this inclined surface by an adhesive member, a low melting point glass welding member, or the like.

[0023] The light transmission plate 53 is a plate-shaped member that transmits the laser beam emitted by the light emitting part and also transmits the laser beam deflected by the light deflection part. The light transmission plate 53 is composed of a material such as optical glass, heat-resistant glass, hard glass, optical plastic, or hard plastic that is translucent to the laser beam emitted by the light emitting part. Anti-reflection films for preventing reflection of the laser beam may be provided on the +Z direction side surface and the -Z direction side surface of the light transmission plate 53.

[0024] Since the end portion on the +Z direction side of the lid 52 in contact with the light transmission plate 53 is inclined with respect to the mounting surface 511, the light transmission plate 53 is held by the lid 52 in an inclined state with respect to the mounting surface 511. By sealing with the lid 52 and the light transmission plate 53, it is possible to prevent dust, dirt, or the like from adhering to the light deflection part provided inside the lid 52 in the light deflection device 50, and to prevent moisture and oxygen from entering the inside of the lid 52.

[0025] <Configuration example of the light deflection part 1> Referring to FIGS. 3 and 4, the configuration of the light deflection unit 1 will be described. FIGS. 3 and 4 are diagrams showing an example of the configuration of the light deflection unit 1. FIG. 3 is a perspective view, and FIG. 4 is a plan view seen from the +Z direction side. FIG. 3 shows a state in which the lid 52 and the light transmission plate 53 are removed in the light deflection device 50, and FIG. 4 shows a state in which the package 51 is further removed from the state of FIG. 3.

[0026] As shown in FIG. 3, the light deflection unit 1 has a movable member 121 that deflects the incident laser beam from the light emitting unit. The light deflection unit 1 is held by the package 51 such that the movable member 121 is disposed near the center of the package 51.

[0027] The movable member 121 has a reflection surface formed on the surface on the +Z direction side, and is configured to be swingable around the first swing axis A and the second swing axis B respectively. The light deflection unit 1 can deflect the laser beam incident on the movable member 121 in the X direction and the Y direction by swinging the movable member 121. The light deflection unit 1 is, for example, a MEMS (Micro Electro Mechanical Systems) mirror that swings the movable member 121 using a piezoelectric element as a drive source. Although a piezoelectric drive type MEMS mirror using a piezoelectric element as a drive source is described as an example, the present invention is not limited thereto, and an electromagnetic drive type or an electrostatic drive type may be used.

[0028] As shown in FIG. 4, the light deflection unit 1 includes a movable member 121, a movable frame 122, a support portion 123, torsion beams 124a and 124b, connection beams 125a and 125b, first drive beams 126a and 126b, second drive beams 130a and 130b, and a fixed frame 133. The light deflection unit 1 also includes a movable frame connection portion 131a, a fixed frame connection portion 132a, a movable frame connection portion 131b, and a fixed frame connection portion 132b.

[0029] The movable frame 122 supports the movable member 121 from the outside. The pair of second drive beams 130a and 130b support the movable frame 122 from both sides.

[0030] The movable frame connection part 131a is the part where the movable frame 122 and the second drive beam 130a are connected. The fixed frame connection part 132a is the part where the fixed frame 133 and the second drive beam 130a are connected. The movable frame connection part 131b is the part where the movable frame 122 and the second drive beam 130b are connected. The fixed frame connection part 132b is the part where the fixed frame 133 and the second drive beam 130b are connected.

[0031] The first drive beam 126a has a drive source 127a. The first drive beam 126b has a drive source 127b. The second drive beam 130a has a drive source 134a. The second drive beam 130b has a drive source 134b.

[0032] The first drive beams 126a and 126b function as actuators that swing the movable member 121 around the first swing axis A to deflect the laser beam. The second drive beams 130a and 130b function as actuators that swing the movable member 121 around the second swing axis B to deflect the laser beam.

[0033] A slit 128 is formed in the support part 123 along the circumference of the movable member 121. The slit 128 can disperse the stress concentration generated by the twisting operation of the twisting beams 24a and 24b to prevent damage to the first reflection surface 22, and can transmit the twist by the twisting beams 124a and 124b to the movable member 121.

[0034] In the light deflection part 1, the movable member 121 is supported on the upper surface of the support part 123. The support part 123 is connected to the ends of the twisting beams 124a and 124b on both sides. The twisting beams 124a and 124b constitute the first swing axis A and extend in the direction of the first swing axis A to support the support part 123 from both sides in the direction of the first swing axis A.

[0035] When the torsion beams 124a and 124b are twisted, the movable member 121 supported by the support portion 123 swings, and an operation is performed to deflect the reflected light of the laser light incident on the movable member 121. Each of the torsion beams 124a and 124b is connected and supported by the connecting beams 125a and 125b, and is connected to the first drive beams 126a and 126b.

[0036] The first drive beams 126a and 126b, the connecting beams 125a and 125b, the torsion beams 124a and 124b, the support portion 123, and the movable member 121 are supported from the outside by the movable frame 122.

[0037] One side of each of the first drive beams 126a and 126b is supported by the movable frame 122. The other side of the first drive beam 126a extends to the inner peripheral side and is connected to the connecting beams 125a and 125b. Similarly, the other side of the first drive beam 126b extends to the inner peripheral side and is connected to the connecting beams 125a and 125b.

[0038] The first drive beams 126a and 126b are provided in a pair so as to sandwich the movable member 121 and the support portion 123 in a direction orthogonal to the torsion beams 124a and 124b. A drive source 127a is formed on the upper surface of the first drive beam 126a, and a drive source 127b is formed on the upper surface of the first drive beam 126b.

[0039] The drive sources 127a and 127b include an upper electrode formed on the piezoelectric thin film (hereinafter also referred to as "piezoelectric thin film") on the upper surface of the first drive beams 126a and 126b, and a lower electrode formed on the lower surface of the piezoelectric thin film. The drive sources 127a and 127b contract according to the polarity of the drive voltage applied to the upper electrode and the lower electrode.

[0040] By alternately applying drive voltages with different phases between the first drive beam 126a and the first drive beam 126b, the first drive beam 126a and the first drive beam 126b vibrate alternately on the upper and lower opposite sides on the left and right sides of the movable member 121.

[0041] Due to the above vibration, the optical deflection unit 1 can swing the movable member 121 around the first swing axis A corresponding to the torsion beams 124a and 124b. For example, by using resonance vibration for the swing drive around the first swing axis A by the first drive beams 126a and 126b, the movable member 121 can be swung at high speed.

[0042] Figures 5A and 5B are diagrams for explaining drive signals. Figure 5A is a diagram showing an example of a horizontal drive signal, and Figure 5B is a diagram showing an example of a vertical drive signal.

[0043] As shown in Figures 5A and 5B, both the horizontal drive signal AHp and the horizontal drive signal AHn are sine waves having the same period and amplitude. The horizontal drive signal AHn is phase-shifted by a half cycle with respect to the horizontal drive signal AHp. That is, the horizontal drive signal AHp and the horizontal drive signal AHn have a relationship in which the potential is inverted with respect to the intermediate potential. The movable member 121 is driven according to the potential difference between the horizontal drive signal AHp and the horizontal drive signal AHn, and the deflection angle (swing angle) of the movable member 121 corresponds to the amplitudes of the horizontal drive signal AHp and the horizontal drive signal AHn.

[0044] Returning to Figure 4, the description of the optical deflection unit 1 is continued. One ends of the second drive beams 130a and 130b are connected to the outside of the movable frame 122 via the movable frame connection portions 131a and 131b. The second drive beams 130a and 130b are provided in pairs so as to sandwich the movable frame 122 from both sides. The second drive beams 130a and 130b support the movable frame 122 from both sides and swing it around the second swing axis B.

[0045] The other end of the second drive beam 130a is connected to the inside of the fixed frame 133 via the fixed frame connection portion 132a. The other end of the second drive beam 130b is connected to the inside of the fixed frame 133 via the fixed frame connection portion 132b.

[0046] As shown in Figure 4, the second drive beam 130a includes a plurality of rectangular vertical beams extending in a direction along the first swing axis A, and a folded-back portion connecting the ends of adjacent vertical beams, and is formed in a zigzag shape as a whole.

[0047] For example, the end of the first vertical beam counted from the side of the first drive beam 126a and the end of the second vertical beam are connected by a folded-back portion. The end of the second vertical beam and the end of the third vertical beam are connected by a folded-back portion. The end of the third vertical beam and the end of the fourth vertical beam are connected by a folded-back portion. The end of the fourth vertical beam and the end of the fifth vertical beam are connected by a folded-back portion. The end of the fifth vertical beam and the end of the sixth vertical beam are connected by a folded-back portion.

[0048] Similarly, the second drive beam 130b includes a plurality of rectangular vertical beams extending in a direction along the first swing axis A and a folded-back portion that connects the ends of adjacent vertical beams, and is formed in a zigzag shape as a whole.

[0049] For example, the end of the first vertical beam counted from the side of the first drive beam 126b and the end of the second vertical beam are connected by a folded-back portion. The end of the second vertical beam and the end of the third vertical beam are connected by a folded-back portion. The end of the third vertical beam and the end of the fourth vertical beam are connected by a folded-back portion. The end of the fourth vertical beam and the end of the fifth vertical beam are connected by a folded-back portion. The end of the fifth vertical beam and the end of the sixth vertical beam are connected by a folded-back portion.

[0050] On the upper surface of the second drive beam 130a, a drive source 134a is formed for each vertical beam, and on the upper surface of the second drive beam 130b, a drive source 134b is formed for each vertical beam. These vertical beams are each a rectangular unit without a curved portion.

[0051] The drive source 134a includes an upper electrode formed on the piezoelectric thin film on the upper surface of the second drive beam 130a and a lower electrode formed on the lower surface of the piezoelectric thin film. The drive source 134b includes an upper electrode formed on the piezoelectric thin film on the upper surface of the second drive beam 130b and a lower electrode formed on the lower surface of the piezoelectric thin film.

[0052] The second drive beams 130a and 130b are between the drive sources 134a and 134b adjacent to each vertical beam. By applying a drive voltage, all the vertical beams are deflected upward, and the accumulation of the vertical movement of each vertical beam is transmitted to the movable frame 122.

[0053] The second drive beams 130a and 130b swing the movable member 121 around the second swing axis B by this operation. For example, non-resonant vibration can be used for the swing by the second drive beams 130a and 130b.

[0054] For example, it is assumed that the drive source 134a includes drive sources 134a1, 134a2, 134a3, 134a4, 134a5, and 134a6 arranged from the movable frame 122 side toward the right. The drive source 134b includes drive sources 134b1, 134b2, 134b3, 134b4, 134b5, and 134b6 arranged from the movable frame 122 side toward the left. In this case, the drive sources 134a1, 134b1, 134a3, 134b3, 134a5, and 134b5 are driven with the same-shaped waveform, and the drive sources 134a2, 134b2, 134a4, 134b4, 134a6, and 134b6 are driven with a waveform obtained by reversing the above same-shaped waveform in time series, whereby the movable member 121 can be remotely moved around the second swing axis B.

[0055] The drive wiring for applying a drive voltage to the upper electrode and the lower electrode of the drive source 127a is connected to a predetermined terminal included in the terminal group 135a provided on the fixed frame 133. The drive wiring for applying a drive voltage to the upper electrode and the lower electrode of the drive source 127b is connected to a predetermined terminal included in the terminal group 135b provided on the fixed frame 133.

[0056] The drive wiring for applying a drive voltage to the upper electrode and the lower electrode of the drive source 134a is connected to a predetermined terminal included in the terminal group 135a provided on the fixed frame 133. The drive wiring for applying a drive voltage to the upper electrode and the lower electrode of the drive source 134b is connected to a predetermined terminal included in the terminal group 135b provided on the fixed frame 133.

[0057] Further, the light deflector 1 includes horizontal piezoelectric sensors 137a and 137b that detect the horizontal inclination (horizontal swing angle) in a state where the movable member 121 is swinging in the horizontal direction, and that are vibration sensors for detecting the emission timing of the laser beam. The horizontal piezoelectric sensors 137a and 137b are provided on the connecting beams 125a and 125b.

[0058] Furthermore, the light deflector 1 includes vertical piezoelectric sensors 136a and 136b that detect the vertical inclination (vertical swing angle) in a state where the movable member 121 is swinging in the vertical direction, and that are vibration sensors for detecting unnecessary vibration of the vertical beam in order to remove unnecessary vibration components from the drive signal. The vertical piezoelectric sensors 136a and 136b are provided on one of the vertical beams that constitute the second drive beams 130a and 130b.

[0059] The light deflector 1 can be manufactured by a semiconductor process using, for example, an SOI (Silicon On Insulator) substrate having a support layer, a buried (BOX: Buried Oxide) layer, and an active layer.

[0060] <Example of reflection of the laser beam L by the lid 52> With reference to FIGS. 6 to 9, the reflection of the laser beam L by the lid 52 will be described. FIG. 6 is a perspective view illustrating the laser beam L passing through the opening 521 in the lid 52.

[0061] The laser beam L is a general term notation when the incident laser beam Li and the deflected laser beam Lo are not particularly distinguished. The incident laser beam Li is an example of incident light from the light emitting portion. The deflected laser beam Lo is an example of deflected light of the incident light by the movable member 121.

[0062] As shown in FIG. 6, the opening 521 includes an incident-side opening 521i through which the incident laser beam Li passes, and an emission-side opening 521o through which the deflected laser beam Lo (an example of deflected light) passes. The opening 521 has a thickness in the Z direction and includes an inner surface 523 which is the inner side surface of the through-hole constituting the opening 521.

[0063] The lid 52 includes a surface 522 on the +Z direction side. The surface 522 corresponds to the surface of the lid 52 on the side opposite to the movable member 121. On the other hand, the surface on the -Z direction side (rear surface) of the lid 52 corresponds to the surface of the lid 52 on the side of the movable member 121.

[0064] In order to reduce the disturbance light entering from the outside to the inside of the optical deflection device 50, it is preferable that the opening width of the opening 521 is as small as possible. Since the incident direction of the incident laser beam Li does not change, the incident-side opening 521i is preferably formed with an opening width slightly larger than the effective beam diameter so as not to block the effective beam diameter of the laser beam L. On the other hand, since the emission direction of the deflected laser beam Lo changes according to the deflection by the movable member 121, the emission-side opening 521o is preferably formed with an opening width such that it does not block the deflected laser beam Lo based on the effective beam width of the laser beam L and the swing angle of the movable member 121.

[0065] In the present embodiment, the incident-side opening width Wiy in the Y direction of the incident-side opening 521i is formed larger than the incident-side opening width Wix in the X direction so that the incident-side opening 521i and the emission-side opening 521o can be formed continuously in the Y direction. The incident-side opening width Wix is formed slightly larger than the effective beam width of the laser beam L. The emission-side opening width Wox in the X direction of the emission-side opening 521o is formed larger than the incident-side opening width Wix according to the swing angle of the movable member 121. The emission-side opening width Woy in the Y direction is formed to be approximately the same as the incident-side opening width Wiy.

[0066] Here, FIG. 7A is a diagram illustrating the cross-sectional intensity distribution of the laser beam L in the X direction. FIG. 7B is a diagram illustrating the cross-sectional intensity distribution of the laser beam L in the Y direction. FIG. 8 is a diagram illustrating the effective beam width of the laser beam L.

[0067] The cross-sectional intensity distribution of the laser beam L refers to the light intensity distribution of the laser beam L along a cross-section further cut by a line passing through the central axis of the laser beam L in a cross-section obtained by cutting the laser beam L with a plane perpendicular to the central axis of the laser beam L. The vertical axis in each of FIGS. 7A and 7B represents the light intensity P of the laser beam L. The horizontal axis in FIG. 7A represents the position in the X direction, and the horizontal axis in FIG. 7B represents the position in the Y direction.

[0068] The cross-sectional intensity distribution of the laser beam L approximately follows a normal distribution. As shown in FIGS. 7A, 7B, and 8, in the cross-sectional intensity distribution of the laser beam L, the maximum beam width Dx2 is the maximum width of the laser beam L in the X direction. The maximum beam width Dy2 is the maximum width of the laser beam L in the Y direction. The effective beam width Dx1 is the full width at half maximum of the laser beam L in the Y direction. The effective beam width Dy1 is the full width at half maximum of the laser beam L in the Y direction.

[0069] When the incident-side aperture width Wix is formed to be larger than the effective beam width Dx1 and smaller than the maximum beam width Dx2, a part of the light corresponding to the region of the incident laser beam Li that is larger than the effective beam width Dx1 enters the surface 522 of the lid 52 and is reflected by the surface 522 in the +Z direction side. This reflected light may become stray light, which is unintended light. Also in the Y direction, depending on the size of the incident-side aperture width Wiy, a part of the light of the incident laser beam Li may enter the surface 522 and be reflected by the surface 522 to become stray light.

[0070] In addition, when the exit-side aperture widths Wox and Woy are formed such that only the effective beam widths Dx1 and Dy1 can pass through, a part of the light in the deflected laser beam Lo corresponding to the region larger than the effective beam widths Dx1 and Dy1 enters the back surface of the lid 52 and is reflected toward the -Z direction side by the back surface. The light reflected by the back surface of the lid 52 may be multiply reflected at the movable member 121, the back surface of the lid 52, etc., and then exit toward the +Z direction side to become stray light.

[0071] Also, on the inner surface 523 of the opening 521, a part of the light in the incident laser beam Li and the deflected laser beam Lo may enter and be reflected by the inner surface 523, thereby becoming stray light.

[0072] In order to suppress stray light, it is also conceivable to provide a diaphragm St that acts as a spatial filter between the light emitting unit and the optical deflector 50. However, as shown in FIG. 9, when the diaphragm diameter Ds is made larger than the effective beam widths Dx1 and Dy1, a part of the light in the laser beam L other than the effective beam widths Dx1 and Dy1 passes through the diaphragm St. Stray light may be generated by this passed light.

[0073] <Configuration Example of Lid 52> In the present embodiment, the lid 52 in the optical deflector 50 includes a light attenuation unit 100 that attenuates the incident laser beam Li or the deflected laser beam Lo reflected by the lid 52. The light attenuation unit 100 is provided on each of the front surface 522, the back surface 524, and the inner surface 523 of the lid 52.

[0074] FIG. 10 is a diagram illustrating the light attenuation unit 100 provided on the front surface 522 of the lid 52 and the inner surface of the opening 521 in the optical deflector 50. FIG. 11 is a diagram illustrating the light attenuation unit 100 provided on the back surface of the lid 52 in the optical deflector 50.

[0075] The light attenuation unit 100 is a light scattering surface that attenuates light, for example, by scattering the light reflected by the lid 52. In FIG. 10, the light attenuation unit 100 is provided on the surface 522 and the inner surface 523 shown by dot hatching. In FIG. 11, the light attenuation unit 100 is provided on the back surface 524 shown by dot hatching.

[0076] FIG. 12 is a diagram for explaining a light scattering surface 100a which is a first example of the light attenuation unit 100. FIG. 12 shows a cross-sectional shape of a part of the light scattering surface 100a. The horizontal axis represents the position j, and the vertical axis represents the height h(j) at each position j.

[0077] The inventor fabricated a plurality of lids 52 with different surface roughnesses on the surface 522, the back surface 524, and the inner surface 523, and earnestly studied by evaluating the stray light of the light deflection device 50 for each lid 52. The evaluation was performed by visually observing the amount and range of the stray light reaching a screen arranged on the +Z direction side (see FIG. 1 etc.) of the light deflection device 50. As a result, it was found that the stray light can be favorably suppressed when the arithmetic mean roughness Ra of the light scattering surface 100a is 0.5 μm or more and 4.5 μm or less. Further, it was found that the stray light can be more favorably suppressed when the arithmetic mean roughness Ra of the light scattering surface 100a is 1.5 μm or more and 3.5 μm or less.

[0078] Here, the arithmetic mean roughness Ra refers to the average of the absolute values of the height h(j) at the reference length u. The average of the absolute values of the height h(j) in the region shown by dot hatching in FIG. 12 corresponds to the arithmetic mean roughness Ra. Note that the range where the arithmetic mean roughness Ra is 0.5 μm or more and 4.5 μm or less corresponds to VDI 15 to VDI 33 in the case of the VDI standard (Verein Deutscher Ingenieure).

[0079] Such a light-scattering surface 100a can be formed, for example, in a mold for molding the lid 52 by roughening the portions corresponding to the front surface 522, the back surface 524, and the inner surface 523 respectively by means of a sandblasting method or a chemical etching method. When aiming for an arithmetic mean roughness Ra of 0.5 μm or more and 2.3 μm or less, it is preferable to apply the chemical etching method, and when aiming for an arithmetic mean roughness Ra of 2.0 μm or more, it is preferable to apply the sandblasting method.

[0080] Further, the light attenuation portion 100 may be, for example, a colored surface capable of absorbing light on the surface of the lid 52 for the light reflected by the lid 52.

[0081] FIG. 13 is a diagram for explaining a colored surface 100b which is a second example of the light attenuation portion 100. FIG. 13 shows a color bar indicating brightness from 0 to 10.

[0082] The inventor fabricated a plurality of lids 52 with different brightness on the front surface 522, the back surface 524, and the inner surface 523, and earnestly studied by evaluating the stray light in the light deflection device 50 for each lid. The evaluation method is the same as the evaluation of the surface roughness described above. As a result, it was found that when the brightness Vd of the colored surface 100b is 0 or more and 5 or less, the stray light can be suppressed well.

[0083] As shown in FIG. 13, for the colored surface 100b, among the brightness Vd of 0 or more and 5 or less, for example, a surface colored black with a brightness of substantially 0 can be applied. Such a colored surface 100b can be formed by painting the surface of the lid 52 with a spray or the like, or by performing a black dyeing treatment on the lid 52 composed of a metal material.

[0084] In this embodiment, a configuration in which the light attenuation portions 100 are provided on each of the front surface 522, the back surface 524, and the inner surface 523 of the lid 52 is illustrated, but the present invention is not limited to this configuration. The light attenuation portions 100 may be provided on at least a part of at least one of the front surface 522, the back surface 524, or the inner surface 523 of the lid 52. When the light attenuation portions 100 are provided partially, it is preferable to provide them around the opening 521 through which the laser beam L passes.

[0085] As a result of evaluating stray light, it was found that the influence of the light reflected from the front surface 522 of the lid 52 on the stray light was the greatest, and the influence of the light reflected from the inner surface 523 was the second greatest. Therefore, the light attenuation portions 100 are preferably provided at least on the front surface 522, and more preferably provided on each of at least the front surface 522 and the inner surface 523.

[0086] <Configuration example of the inner surface 523 of the opening 521> With reference to FIGS. 14 to 16, the inner surface 523 of the opening 521 will be described.

[0087] FIG. 14 is a perspective view for explaining the configuration of the inner surface 523 in the opening 521. FIG. 14 shows a state in which the lid 52 is cut by a plane orthogonal to the X axis. FIG. 15 is a cross-sectional view for explaining an example of the inclination of the first inner surface 523a in the opening 521. FIG. 16 is a cross-sectional view for explaining an example of the inclination of the second inner surface 523b in the opening 521. In FIGS. 15 and 16, the movable member 121 is inclined to the maximum deflection angle D from the stationary state.

[0088] As shown in FIG. 14, the inner surface 523 is formed to be inclined with respect to the front surface 522 of the lid 52. The appropriate value of the inclination angle of the inner surface 523 varies depending on the position of the inner surface 523 among the plurality of inner surfaces 523 included in the opening 521.

[0089] As shown in FIG. 15, the first inner surface 523a is a surface that, among the plurality of inner surfaces 523, is disposed on the side opposite to the side where the incident laser beam Li enters the movable member 121, with the stationary central axis 121c (see FIG. 15), which is the central axis of the movable member 121 when it is stationary, interposed therebetween.

[0090] The incident laser beam Li travels in a direction inclined at an angle C with respect to the stationary central axis 121c and enters the movable member 121. Note that the incident laser beam Li in FIG. 15 represents the central axis of the incident laser beam. In FIG. 15, the deflected laser beam Lo deflected by the movable member 121 is reflected by the first inner surface 523a. The reflected light Ln1 represents the light reflected by the first inner surface 523a.

[0091] In this embodiment, when the angle formed by the first inner surface 523a and the surface 522 of the lid 52 is θ1, the following equation (1) is satisfied. θ1 ≦ C + 2 × D ···(1)

[0092] Also, as shown in FIG. 16, the second inner surface 523b is a surface other than the first inner surface 523a among the plurality of inner surfaces 523 included in the opening 521.

[0093] The incident laser beam Li travels in a direction substantially parallel to the stationary central axis 121c and enters the movable member 121. In FIG. 16, the deflected laser beam Lo deflected by the movable member 121 is reflected by the second inner surface 523b. The reflected light Ln2 represents the light reflected by the second inner surface 523b.

[0094] In this embodiment, when the angle formed by the second inner surface 523b and the surface 522 of the lid 52 is θ2, the following equation (2) is satisfied. θ2 ≦ 2 × D ···(2)

[0095] By satisfying the conditions of the above formulas (1) and (2), among the deflected laser beams Lo, the reflected light Ln1 reflected by the first inner surface 523a and the reflected light Ln2 reflected by the second inner surface 523b do not travel to the side opposite to the movable member 121 across the surface 522 and are not emitted from the optical deflector 50. As a result, the optical deflector 50 can prevent stray light generated by reflection from the first inner surface 523a and the second inner surface 523b.

[0096] <Operation and Effect of Optical Deflector 50> As described above, the optical deflector 50 includes a movable member 121 that deflects an incident laser beam Li (incident light) from a light emitting unit, and a lid 52 (lid member) that covers the movable member 121. The lid 52 includes an opening 521 through which the incident laser beam Li and the deflected laser beam Lo (deflected light) deflected by the movable member 121 of the incident laser beam Li pass. The lid 52 also includes a light attenuation unit 100 that attenuates the incident laser beam Li or the deflected laser beam Lo reflected by the lid 52.

[0097] For example, the light attenuation unit 100 is a light scattering surface 100a having an arithmetic mean roughness Ra of 0.5 μm or more and 4.5 μm or less. Alternatively, the light attenuation unit 100 is a colored surface 100b having a lightness of 0 or more and 5 or less. The light scattering surface 100a preferably has an arithmetic mean roughness Ra of 1.5 μm or more and 3.5 μm or less.

[0098] The light attenuation unit 100 is provided, for example, on at least a part of at least one of the surface 522 (the surface on the movable member side), the back surface 524 (the surface opposite to the movable member), or the inner surface 523 of the opening 521 in the lid 52.

[0099] By including the light attenuation unit 100, the optical deflector 50 can attenuate the incident laser beam Li or the deflected laser beam Lo reflected by the lid 52. Thereby, an optical deflector 50 capable of suppressing stray light can be provided.

[0100] <Modification Example> The lid according to the embodiment can be deformed into various shapes. Hereinafter, an optical deflection device according to a modified example having lids of various shapes will be described.

[0101] (First Modified Example) FIG. 17 is a perspective view illustrating the configuration of an optical deflection device 50a according to the first modified example. FIG. 18 is a perspective view showing a state where the light transmission plate 53a is removed from the optical deflection device 50a. FIG. 19 is a view showing a light attenuation portion 100 provided on the front surface 522a of the lid 52a and the inner surface 523aa of the opening 521a included in the optical deflection device 50a. FIG. 20 is a view showing the light attenuation portion 100 provided on the back surface 524a of the lid 52a.

[0102] As shown in FIGS. 17 to 20, the optical deflection device 50a includes a package 51a, a lid 52a, and a light transmission plate 53a. The lid 52a is provided on the +Z direction side of the package 51a that houses the optical deflection portion 1. The lid 52a holds the light transmission plate 53a. The planar shape of the lid 52a viewed from the Z direction side is a substantially rectangular shape that is long along the X direction.

[0103] Also in the optical deflection device 50a, the light attenuation portion 100 can be provided on at least a part of at least one of the front surface 522a, the back surface 524a, or the inner surface 523aa of the opening 521a of the lid 52a. The optical deflection device 50a can attenuate the incident laser beam Li or the deflected laser beam Lo reflected by the lid 52a by the light attenuation portion 100. Thereby, an optical deflection device 50a capable of suppressing stray light can be provided.

[0104] (Second Modified Example) FIG. 21 is a perspective view illustrating the configuration of an optical deflection device 50b according to the second modified example. FIG. 22 is a view showing the light attenuation portion 100 provided on the front surface 522b of the lid 52b and the inner surface 523bb of the opening 521b included in the optical deflection device 50b. FIG. 23 is a view showing the light attenuation portion 100 provided on the back surface 524b of the lid 52b.

[0105] As shown in FIGS. 21 to 23, the light deflection device 50b includes a package 51b and a lid 52b. The lid 52b is provided on the +Z direction side of the package 51b that houses the light deflection unit 1 inside. The light deflection device 50b does not have a light transmission plate. Also, the lid 52b does not have an inclined portion for holding the light transmission plate in an inclined manner. The shape of the lid 52b in a plan view as viewed from the Z direction side is a substantially rectangular shape that is long along the X direction.

[0106] Also in the light deflection device 50b, the light attenuation portion 100 can be provided on at least a part of at least one of the front surface 522b, the back surface 524b, or the inner surface 523bb of the opening 521b of the lid 52b. The light deflection device 50b can attenuate the incident laser beam Li or the deflected laser beam Lo reflected by the lid 52b by the light attenuation portion 100. Thereby, a light deflection device 50b capable of suppressing stray light can be provided.

[0107] Although the embodiments have been described above, the present invention is not limited to the specifically disclosed above embodiments, and various modifications and changes can be made without departing from the scope of the claims.

[0108] As examples of the shape of the lid, those having a substantially square shape and a substantially rectangular shape in a plan view as viewed from the Z direction side are illustrated, but the present invention is not limited thereto, and various shapes such as a substantially circular shape, an elliptical shape, and a polygonal shape can be used.

[0109] The numbers such as ordinal numbers and quantities used in the description of the embodiments are all exemplified for specifically explaining the technology of the present invention, and the present invention is not limited to the exemplified numbers.

[0110] The light deflection device according to the embodiment can be used, for example, in an image projection device that projects an image on a scanned surface to deflect light and scan it on the scanned surface. Examples of the image projection device include a projector, a vehicle welcome projector, a head-up display, a head-mounted display, a vehicle headlamp, an object recognition device, a distance measuring device, or an ophthalmic examination device.

[0111] A vehicle welcome projector refers to a projector provided on a vehicle door or the like that projects a desired image including a logo or the like when the door is opened. An object recognition device refers to a device that detects and recognizes the presence, shape, or distance to an object based on the reflected light or scattered light of the projected light by the object.

Explanation of Reference Numerals

[0112] 1 ··· Light deflection unit, 100 ··· Light attenuation unit, 100a ··· Light scattering surface, 100b ··· Coloring surface, 121 ··· Movable member, 121c ··· Stationary central axis, 122 ··· Movable frame, 123 ··· Support part, 124a, 124b ··· Twisted beams, 125a, 125b ··· Connecting beams, 126a, 126b ··· First drive beams, 127a, 127b ··· Drive sources, 128 ··· Slit, 130a, 130b ··· Second drive beams, 131a, 131b ··· Movable frame connection parts, 132a, 132b ··· Fixed frame connection parts, 133 ··· Fixed frame, 134a, 134b ··· Drive sources, 135a, 135b ··· Terminal groups, 136a, 136b ··· Vertical piezoelectric sensors, 137a, 137b ··· Horizontal piezoelectric sensors, 50 ··· Light deflection device, 51 ··· Package, 511 ··· Mounting surface, 52 ··· Lid (an example of a lid member), 521 ··· Opening, 521i ··· Incident side opening, 521o ··· Exit side opening, 522 ··· Surface, 523 ··· Inner surface, 523a ··· First inner surface, 523b ··· Second inner surface, 524 ··· Back surface, 53 ··· Light transmission plate, A ··· First swing axis, B ··· Second swing axis, L ··· Laser beam, Li ··· Incident laser beam (an example of incident light), Lo ··· Deflected laser beam (an example of deflected light), Wix, Wiy ··· Incident side opening width, Wox, Woy ··· Exit side opening width, Dx1, Dy1 ··· Effective beam width, Dx2, Dy2 ··· Maximum beam width, Ds ··· Aperture diameter, St ··· Aperture, Ra ··· Arithmetic mean roughness, u ··· Reference length, Vd ··· Luminance, θ1, θ2, C ··· Angles, D ··· Maximum deflection angle, Ln1, Ln2 ··· Reflected light

Claims

1. A movable member that deflects incident light from a light emitting unit in two directions orthogonal to each other, and a lid member that covers the movable member, wherein the lid member has an opening that allows the incident light and the deflected light of the incident light by the movable member to pass through, and a light attenuation unit that reduces reflection of the incident light in the lid member or reflection of the deflected light in the lid member, wherein the light attenuation unit is provided on at least a part of at least one of a surface of the lid member on the movable member side, a surface of the lid member on the side opposite to the movable member side, and an inner surface of the opening, wherein the opening includes a first opening through which the incident light passes, and a second opening through which the deflected light passes, and when viewed from a direction orthogonal to each of the two directions, in a direction orthogonal to the direction in which the incident light is incident, an opening width of the second opening is larger than an opening width of the first opening. A light deflection device characterized by this.

2. The light deflection device according to claim 1, wherein the light attenuation unit is a light scattering surface having an arithmetic mean roughness Ra of 0.5 μm or more and 4.5 μm or less.

3. The light deflection device according to claim 1 or 2, wherein the light attenuation unit is a light scattering surface having an arithmetic mean roughness Ra of 1.5 μm or more and 3.5 μm or less.

4. The light deflection device according to claim 1, wherein the light attenuation unit is a colored surface having a lightness of 0 or more and 5 or less.

5. A movable member that deflects incident light from a light emitting unit, and a lid member that covers the movable member, wherein the lid member has an opening that allows the incident light and the deflected light of the incident light by the movable member to pass through, and a light attenuation unit that reduces reflection of the incident light in the lid member or reflection of the deflected light in the lid member, wherein the opening includes a first inner surface and a second inner surface, wherein the first inner surface is a surface disposed on a side opposite to a side where the incident light enters the movable member with respect to a stationary central axis that is a central axis of the movable member when stationary, among a plurality of inner surfaces included in the opening, wherein the second inner surface is a surface other than the first inner surface among the plurality of inner surfaces included in the opening, when an angle formed by the first inner surface and a surface of the lid member on the side opposite to the movable member is θ1, and an angle formed by the second inner surface and a surface of the lid member on the side opposite to the movable member is θ2, a light deflection device that satisfies the following formulas (1) and (2). θ1 ≦ C + 2 × D... (1) θ2 ≦ 2 × D... (2) (However, C represents the angle formed by the stationary central axis and the central axis of the incident light, and D represents the maximum deflection angle of the movable member.)

Images