Optical deflection device and image projection device

Abstract

To prevent a projected image from including the reflected light from a light transmitting plate.SOLUTION: An optical deflection device according to one aspect of the present invention includes: an optical deflection part (12) for deflecting light incident on the reflection surface (121) by swinging the reflection surface (121) around an oscillation axis; and a light transmitting plate (3) which transmits the light deflected by the light deflection part (12). An inclination angle (θ) of the light transmitting plate (3) with respect to the reference surface (111) is equal to or more than 2 times of a maximum deflection angle (α) of the reflection surface (121) with respect to the reference surface (111).SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an optical deflection device and an image projection device. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there is known an image projection device that projects an image onto a surface to be scanned by using a light deflection device that deflects light emitted from a light emitting portion with a reflecting surface.

[0003] In addition, in order to prevent abnormal images from occurring on the scanned surface, a configuration has been disclosed in which the maximum deflection angle of the reflecting surface relative to the reference surface is made smaller than the inclination angle of the light-transmitting plate relative to the reference surface (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6627994 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the configuration of Patent Document 1, the projected image may contain reflected light from the light-transmitting plate, which may degrade the image quality.

[0006] An object of the present invention is to prevent light reflected from a light-transmitting plate from being included in a projected image. [Means for solving the problem]

[0007] The optical deflection device according to one aspect of the present invention includes an optical deflection unit (12) that deflects light incident on a reflecting surface (121) by swinging the reflecting surface (121) around a swing axis, and a reflecting surface (122) that transmits the light deflected by the optical deflection unit (12). and projecting an image onto the surface to be scanned (200).and a light transmitting plate (3) that is arranged to deflect the light incident on the reflecting surface (121) in two intersecting directions by swinging the reflecting surface (121) around both a first axis (A) and a second axis (B) that intersects with the first axis (A), and a first maximum deflection angle (α) of the reflecting surface (121) around the first axis (A) with respect to a reference plane (111) is set to be 1 / 2. 1 ) is the second maximum deflection angle (α) of the reflecting surface (121) relative to the reference plane (111) about the second axis (B). 2 ), and the inclination angle (θ) of the light-transmitting plate (3) with respect to the reference surface (111) is greater than the second maximum deflection angle (α 2 ) is more than twice as much as and is determined so as to prevent the light reflected by the surface of the light-transmitting plate (3), returning to the light deflection unit (12), being reflected by the reflecting surface (121), and passing through the light-transmitting plate (3) from reaching the surface to be scanned (200). do.

[0008] The reference symbols in parentheses are given for ease of understanding, are merely examples, and are not intended to be limiting of the embodiments shown in the drawings. Effect of the Invention

[0009] According to the present invention, it is possible to prevent the reflected light from the light-transmitting plate from being included in the projected image. [Brief description of the drawings]

[0010] [Figure 1] 1 is a perspective view showing an example of the overall configuration of an image projection device according to an embodiment. [Diagram 2] 2A, 2B, 2C, and 2D are diagrams showing an example of the configuration of an optical deflection device according to an embodiment, in which FIG. 2A is a top view, FIG. 2B is a left side view, FIG. 2C is a front view, and FIG. 2D is a right side view. [Diagram 3] FIG. 2 is a perspective view illustrating a configuration example of a light deflection unit according to the embodiment. [Figure 4] 5A and 5B are diagrams illustrating an example of the configuration of a light deflection unit according to the embodiment. [Diagram 5] 5A and 5B are diagrams for explaining drive signals, where FIG. 5A is a diagram showing an example of a horizontal drive signal, and FIG. 5B is a diagram showing an example of a vertical drive signal. [Figure 6]3A to 3C are diagrams illustrating an example of incidence and emission of laser light in the optical deflection device according to the embodiment. [Figure 7] 10A and 10B are cross-sectional views showing the effect of tilting the light-transmitting plate according to the embodiment. [Figure 8] 11A and 11B are cross-sectional views showing the effect of tilting a light-transmitting plate according to a comparative example. [Figure 9] 11 is a perspective view showing another first example of the light deflection unit according to the embodiment. FIG. [Figure 10] FIG. 11 is a perspective view showing another second example of the light deflection unit according to the embodiment. [Figure 11] 10A and 10B are diagrams illustrating other examples of the inclination of the light-transmitting plate according to the embodiment. [Figure 12] 12A and 12B are diagrams showing a first example of a combination of the height of incident laser light and the inclination of a light-transmitting plate, in which FIG. 12A is a perspective view and FIG. 12B is a cross-sectional view taken along line TT in FIG. 12A. [Figure 13] 13A and 13B are diagrams showing a second example of a combination of the height of incident laser light and the inclination of a light-transmitting plate, in which FIG. 13A is a perspective view and FIG. 13B is a cross-sectional view taken along line UU in FIG. 13A. [Figure 14] 14A and 14B are diagrams showing a third example of a combination of the height of incident laser light and the inclination of a light-transmitting plate, in which FIG. 14A is a perspective view and FIG. 14B is a cross-sectional view taken along line VV of FIG. 14A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and duplicated explanations may be omitted.

[0012] Furthermore, the embodiments shown below are examples of an optical deflection device and an image projection device for embodying the technical concept of the present invention, and the present invention is not limited to the embodiments shown below. The dimensions, materials, shapes, relative positions, etc. of the components described below are intended to be illustrative, and not to limit the scope of the present invention, unless otherwise specified. Furthermore, the sizes and positional relationships of the components shown in the drawings may be exaggerated to clarify the explanation.

[0013] The optical deflection device of the embodiment has an optical deflection unit that deflects light incident on the reflective surface by oscillating the reflective surface around an oscillation axis, and a light transmitting plate that transmits the light deflected by the optical deflection unit.

[0014] Such an optical deflection device is used, for example, in an image projection device that projects an image onto a scanned surface, to deflect light and scan the scanned surface. Examples of the image projection device include a projector, a welcome projector for a vehicle, a head-up display, a head-mounted display, a headlamp for a vehicle, an object recognition device, a distance measuring device, and an eye fundus examination device.

[0015] The welcome projector of a vehicle refers to a projector that is installed on the door of a vehicle and projects a desired image, including a logo, when the door is opened. The object recognition device refers to a device that detects and recognizes the presence or absence, shape, or distance to an object based on the reflected or scattered light of the projected light by the object.

[0016] When the above-mentioned light deflection device is used in an image projection device or the like, a part of the light deflected by the light deflection unit may be reflected back to the light deflection unit without passing through the light-transmitting plate, and may be deflected by the reflecting surface again. Also, a part of the light deflected again may be reflected back to the light deflection unit without passing through the light-transmitting plate, and may be deflected by the reflecting surface again.

[0017] When the light reflected by such a light-transmitting plate is included in the projected image, multiple images or moire patterns, in which multiple images are visually perceived as overlapping, may occur.

[0018] Furthermore, if a light-emitting unit that emits light onto a reflective surface is disposed on the opposite side of the reflective surface with a light-transmitting plate sandwiched therebetween, and the light from the light-emitting unit is incident on the reflective surface after passing through the light-transmitting plate, the light reflected by the light-transmitting plate may be included in the projected image. When the reflected light of the incident light is included in the projected image, point-like stray light or the like may occur.

[0019] Since the light-transmitting plate includes a first surface and a second surface opposite to the first surface, overlapping images and point-like stray light may occur due to light reflected from each of the first surface and the second surface.

[0020] In contrast, in the embodiment, the inclination angle of the light-transmitting plate with respect to the reference surface is set to at least twice the maximum deflection angle of the reflecting surface with respect to the reference surface, so that the projected image does not include secondary reflected light from the light-transmitting plate, thereby making it possible to ensure high quality of the projected image.

[0021] Here, the reference surface refers to a surface that is a reference for the tilt of the reflecting surface due to the swing, and also refers to a surface that is a reference for the tilt of the light-transmitting plate. The deflection angle refers to the angle at which the reflecting surface is tilted with respect to the reference surface due to the swing. The maximum deflection angle refers to the largest of the deflection angles.

[0022] In addition, the term "deflection of light" in the embodiments refers to changing the traveling direction of light. In the embodiments, the reflective surface deflects light by reflecting the light.

[0023] Hereinafter, the embodiment will be described by taking an image projection device having a light deflection device according to the embodiment as an example.

[0024] In the figures shown below, directions may be indicated by the X-axis, Y-axis, and Z-axis, and the X-direction along the X-axis indicates the direction in which the optical deflection unit of the optical deflection device according to the embodiment deflects light to perform scanning. The Y-direction along the Y-axis indicates the direction in which the optical deflection unit of the optical deflection device according to the embodiment deflects light to perform scanning, and indicates a direction substantially perpendicular to the X-axis. The Z-direction along the Z-axis indicates a direction substantially perpendicular to both the X-axis and the Y-axis.

[0025] Additionally, the direction in which the arrow points in the X direction is denoted as the +X direction, and 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, and the opposite direction of the +Y direction is denoted as the -Y direction, and 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 of the optical deflection device and image projection device when in use, and the optical deflection device and image projection device can be disposed in any orientation.

[0026] <Configuration Example of Image Projection Device 100> First, the overall configuration of an image projection device 100 according to the embodiment and the configuration of a light deflection device 20 included in the image projection device 100 will be described with reference to FIGS.

[0027] Fig. 1 is a perspective view for explaining an example of the overall configuration of an image projection device 100. Fig. 2 is a view for explaining an example of the configuration of an optical deflection device 20. Fig. 2(a) is a top view, Fig. 2(b) is a left side view, Fig. 2(c) is a front view, and Fig. 2(d) is a right side view.

[0028] 1, the image projection device 100 includes a light emitting unit 10, a light deflection device 20, and a control unit 30. These are provided in a housing that the image projection device 100 includes.

[0029] Under the control of the control unit 30, the image projection device 100 scans laser light of each wavelength of red, green, blue, and IR (infrared) emitted by the light emitting unit 10 in the X direction and Y direction, respectively, using the optical deflection device 20, and projects a full-color image 201 onto the scanned surface 200.

[0030] In this embodiment, as an example, the Y direction corresponds to the direction of gravity, and the X direction corresponds to the horizontal direction substantially perpendicular to the direction of gravity. The optical deflection device 20 deflects the laser light of each wavelength of Red, Green, Blue, and IR emitted by the light emitting unit 10, and scans the scanned surface 200 in two directions, the X direction and the Y direction.

[0031] However, the image 201 projected by the image projection device 100 is not limited to a full-color image, and may be a monochrome image, etc. When projecting a monochrome image, the image projection device 100 scans the scanned surface 200 with a monochrome laser light.

[0032] When the image projection device 100 is a projector, the scanned surface 200 corresponds to a screen, etc. When the image projection device 100 is a head-up display, the scanned surface 200 corresponds to a front windshield of an automobile, etc.

[0033] Furthermore, if the image projection device 100 is a head mounted display or an ophthalmoscopic device, the scanned surface 200 corresponds to a holographic optical element, the retina of an eye, etc. If the image projection device 100 is a headlamp of a vehicle, an object recognition device, or a distance measuring device, it corresponds to a virtual plane in space.

[0034] The light-emitting unit 10 has an LD (Laser Diode) that emits red laser light, an LD that emits green laser light, an LD that emits blue laser light, and an LD that emits IR laser light. The light-emitting unit 10 causes the laser light of each wavelength of red, green, blue, and IR emitted by the LD of each color to enter the optical deflection device 20. The laser light of each color is an example of light emitted by the light-emitting unit.

[0035] 1 and 2, the optical deflection device 20 has an optical deflection unit 1, a lid 2, and a light-transmitting plate 3. The lid 2 is provided on the +Z direction side of the optical deflection unit 1, and the light-transmitting plate 3 is provided on the +Z direction side of the lid 2.

[0036] The optical deflection unit 1 includes an optical deflection section and a package 11, and has a function of deflecting a laser beam emitted by a light emitting section .

[0037] The package 11 is a box-shaped member that holds an optical deflection unit therein. The package 11 is made of alumina ceramics, metal materials such as aluminum, aluminum alloy, and stainless steel, or plastic materials. The package 11 also includes a circuit board made of FRP (Fiber Reinforced Plastics), FPC (Flexible printed circuits), or the like.

[0038] The configuration and function of the optical deflection unit will be described separately with reference to FIGS.

[0039] The lid 2 is a cylindrical member having a rectangular cross section and made of a material such as alumina ceramics, aluminum, an aluminum alloy, stainless steel, or plastic. The lid 2 is fixed by an adhesive or the like with the end on the -Z direction side in contact with a mounting surface 111 provided on the +Z direction side of the package 11. This mounting surface 111 corresponds to an example of a reference surface.

[0040] The end of the lid 2 on the +Z direction side is formed with a surface inclined with respect to the mounting surface 111. With this inclined surface of the lid 2 in contact with the light-transmitting plate 3, the lid 2 fixes and holds the light-transmitting plate 3 by adhesive, low-melting glass welding, or the like.

[0041] The light-transmitting plate 3 is a plate-like member that transmits the laser light emitted by the light-emitting section 10 and also transmits the laser light deflected by the light deflection section included in the light deflection unit 1. The light-transmitting plate 3 has both a function as an entrance window that allows the laser light to enter the inside of the light deflection device 20 from the outside, and a function as an exit window that allows the laser light to exit from the inside of the light deflection device 20 to the outside.

[0042] Such a light-transmitting plate 3 is made of materials such as optical glass, heat-resistant glass, hard glass, optical plastic, hard plastic, etc., that are optically transparent to the wavelengths of the laser light of each color emitted by the light-emitting unit 10. An anti-reflection film is provided on a first surface of the light-transmitting plate 3 and a second surface opposite to the first surface, respectively, to prevent reflection of the incident laser light.

[0043] The end of the lid 2 on the +Z direction side with which the light-transmitting plate 3 is in contact is inclined with respect to the mounting surface 111, so the light-transmitting plate 3 is also held by the lid 2 in a state inclined with respect to the mounting surface 111. The sealing by the lid 2 and the light-transmitting plate 3 prevents the adhesion of dirt or dust to the light deflection section of the light deflection unit 1 and the intrusion of moisture or oxygen.

[0044] The control unit 30 applies a driving signal such as a driving voltage to the light-emitting unit 10 to control the light emission of the LD of each color of the light-emitting unit 10. The control unit 30 also applies a driving signal such as a driving voltage to the light deflection device 20 to control the scanning of the laser light by the light deflection device 20.

[0045] The functions of the control unit 30 can be realized by electric circuits, and some or all of the functions can be realized by software (CPU: Central Processing Unit).

[0046] <Configuration example of optical deflection unit 1> Next, the configuration of the light deflection unit 1 will be described with reference to Fig. 3 and Fig. 4. First, Fig. 3 is a perspective view for explaining an example of the configuration of the light deflection unit 1. Fig. 3 shows a state in which the lid 2 and the light transmitting plate 3 in the light deflection device 20 have been removed.

[0047] 3, the light deflection unit 1 has a package 11 and a light deflection section 12. The light deflection section 12 is held in the package 11 such that a reflecting surface 121 of the light deflection section 12 is disposed near the center of the package 11. The light deflection unit 1 may include a circuit in the package 11, or may include a substrate, a control circuit, and the like below the package 11.

[0048] The optical deflection unit 12 deflects the laser light incident on the reflecting surface 121 by swinging the reflecting surface 121 around a first swing axis A and a second swing axis B. The optical deflection unit 12 is, for example, a MEMS (Micro Electro Mechanical Systems) mirror that swings the reflecting surface 121 by a piezoelectric element. Here, the first swing axis A is an example of an swing axis and an example of a first axis. The second swing axis B is an example of a second axis.

[0049] Next, Fig. 4 is a diagram illustrating an example of the configuration of the light deflection unit 12. As shown in Fig. 4, the light deflection unit 12 has a reflecting surface 121, a movable frame 122 that supports the reflecting surface 121 from the outside, and a pair of second actuation beams 130a and 130b that support the movable frame 122 from both sides.

[0050] The movable frame connection portion 131a is a portion where the movable frame 122 and the second actuation beam 130a are connected, and the fixed frame connection portion 132a is a portion where the fixed frame 133 and the second actuation beam 130a are connected.

[0051] The movable frame connection portion 131b is a portion where the movable frame 122 and the second actuation beam 130b are connected, and the fixed frame connection portion 132b is a portion where the fixed frame 133 and the second actuation beam 130b are connected.

[0052] The optical deflection unit 12 includes a reflecting surface 121, a movable frame 122, a support unit 123, torsion beams 124a and 124b, connecting beams 125a and 125b, first actuation beams 126a and 126b, second actuation beams 130a and 130b, and a fixed frame 133.

[0053] The first actuation beam 126a has an actuation source 127a, and the first actuation beam 126b has an actuation source 127b. The second actuation beam 130a has an actuation source 134a, and the second actuation beam 130b has an actuation source 134b.

[0054] The first actuation beams 126a and 126b function as actuators that oscillate the reflecting surface 121 around a first oscillation axis A to deflect the laser light. The second actuation beams 130a and 130b function as actuators that oscillate the reflecting surface 121 around a second oscillation axis B to deflect the laser light.

[0055] A slit 128 is formed in the support portion 123 along the circumference of the reflecting surface 121. The slit 128 disperses stress concentration caused by the twisting action of the torsion beams 24a and 24b, thereby preventing damage to the first reflecting surface 22 and transmitting the torsion caused by the torsion beams 124a and 124b to the reflecting surface 121.

[0056] In the optical deflection unit 12, the reflecting surface 121 is supported on the upper surface of the support unit 123, and the support unit 123 is connected to ends of torsion beams 124a and 124b on both sides. The torsion beams 124a and 124b form a first oscillation axis A and extend in the direction of the first oscillation axis A to support the support unit 123 from both sides in the direction of the first oscillation axis A.

[0057] When the torsion beams 124a and 124b are twisted, the reflection surface 121 supported by the support portion 123 swings, and the reflected light of the laser light incident on the reflection surface 121 is deflected and scanned. The torsion beams 124a and 124b are connected and supported by connection beams 125a and 125b, respectively, and connected to first actuation beams 126a and 126b.

[0058] The first actuation beams 126a and 126b, the connecting beams 125a and 125b, the torsion beams 124a and 124b, the support portion 123, and the reflecting surface 121 are supported from the outside by a movable frame 122.

[0059] One side of each of the first actuation beams 126a and 126b is supported by the movable frame 122. The other side of the first actuation beam 126a extends toward the inner periphery and is connected to the connecting beams 125a and 125b. Similarly, the other side of the first actuation beam 126b also extends toward the inner periphery and is connected to the connecting beams 125a and 125b.

[0060] The first actuation beams 126a and 126bB are provided in a pair in a direction perpendicular to the torsion beams 124a and 124b, sandwiching the reflecting surface 121 and the support portion 123. A drive source 127a is formed on the upper surface of the first actuation beam 126a, and a drive source 127b is formed on the upper surface of the first actuation beam 126b.

[0061] The driving sources 127a and 127b include an upper electrode formed on a thin film (hereinafter also referred to as a "piezoelectric thin film") of a piezoelectric element on the upper surface of the first driving beams 126a and 126b, and a lower electrode formed on the lower surface of the piezoelectric thin film. The driving sources 127a and 127b contract according to the polarity of the driving voltage applied to the upper electrode and the lower electrode.

[0062] Therefore, when drive voltages of different phases are alternately applied to the first drive beams 126a and 126b, the first drive beams 126a and 126b on the left and right sides of the reflecting surface 121 alternately vibrate in opposite directions.

[0063] As a result, the torsion beams 124a and 124b serve as a first oscillation axis A, and the reflection surface 121 can be oscillated around the first oscillation axis A. For example, resonant vibration is used for the oscillation drive around the first oscillation axis A by the first actuation beams 126a and 126b, and the reflection surface 121 can be oscillated at high speed.

[0064] Here, FIG. 5 is a diagram for explaining the drive signals, where FIG. 5(a) is a diagram showing an example of a horizontal drive signal, and FIG. 5(b) is a diagram showing an example of a vertical drive signal.

[0065] 5, the horizontal drive signals AHp and AHn are both sine waves having the same period and amplitude, and the horizontal drive signal AHn is out of phase with the horizontal drive signal AHp by a half period. That is, the horizontal drive signals AHp and AHn have an inverted potential relationship with respect to the intermediate potential. The first reflecting surface 22 is driven in response to the potential difference between the horizontal drive signals AHp and AHn, and the deflection angle corresponds to the amplitude of the horizontal drive signals AHp and AHn.

[0066] Returning to Fig. 4, one ends of the second drive beams 130a and 130b are connected to the outside of the movable frame 122 via movable frame connecting parts 131a and 131b. The second drive beams 130a and 130b are provided in pairs 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.

[0067] The other end of the second actuation beam 130a is connected to the inside of the fixed frame 133 via a fixed frame connecting portion 132a. The other end of the second actuation beam 130b is connected to the inside of the fixed frame 133 via a fixed frame connecting portion 132b.

[0068] As shown in FIG. 4, the second drive beam 130a includes a plurality of rectangular vertical beams extending in a direction along the first oscillation axis A and folded portions connecting the ends of adjacent vertical beams, and has an overall zigzag shape.

[0069] For example, counting from the first actuation beam 126a side, the end of the first vertical beam and the end of the second vertical beam are connected by a folded portion. Also, the end of the second vertical beam and the end of the third vertical beam are connected by a folded portion. Also, the end of the third vertical beam and the end of the fourth vertical beam are connected by a folded portion. Also, the end of the fourth vertical beam and the end of the fifth vertical beam are connected by a folded portion. Also, the end of the fifth vertical beam and the end of the sixth vertical beam are connected by a folded portion.

[0070] Similarly, the second drive beam 130b also includes a plurality of rectangular vertical beams extending in the direction along the first oscillation axis A and folded portions connecting the ends of adjacent vertical beams, and has an overall zigzag shape.

[0071] For example, counting from the first actuation beam 126b side, the end of the first vertical beam and the end of the second vertical beam are connected by a folded portion. Also, the end of the second vertical beam and the end of the third vertical beam are connected by a folded portion. Also, the end of the third vertical beam and the end of the fourth vertical beam are connected by a folded portion. Also, the end of the fourth vertical beam and the end of the fifth vertical beam are connected by a folded portion. Also, the end of the fifth vertical beam and the end of the sixth vertical beam are connected by a folded portion.

[0072] On the upper surface of the second actuation beam 130a, a drive source 134a is formed for each vertical beam, which is a rectangular unit that does not include a curved portion. On the upper surface of the second actuation beam 130b, a drive source 134b is formed for each vertical beam, which is a rectangular unit that does not include a curved portion.

[0073] The driving source 134a includes an upper electrode formed on the piezoelectric thin film on the upper surface of the second driving beam 130a and a lower electrode formed on the lower surface of the piezoelectric thin film. The driving source 134b includes an upper electrode formed on the piezoelectric thin film on the upper surface of the second driving beam 130b and a lower electrode formed on the lower surface of the piezoelectric thin film.

[0074] The second actuation beams 130a and 130b bend all the vertical beams upward by applying a drive voltage between adjacent actuation sources 134a and 134b for each vertical beam, and transmit the accumulated up and down movement of each vertical beam to the movable frame 122.

[0075] By this operation, the second actuation beams 130a and 130b oscillate the reflecting surface 121 around the second oscillation axis B. For example, non-resonant vibration can be used for the oscillation caused by the second actuation beams 130a and 130b.

[0076] For example, the driving source 134a includes driving sources 134a1, 134a2, 134a3, 134a4, 134a5, and 134a6 arranged from the movable frame 122 side toward the right side. The driving source 134b includes driving sources 134b1, 134b2, 134b3, 134b4, 134b5, and 134b6 arranged from the movable frame 122 side toward the left side. In this case, the reflecting surface 121 can be oscillated around the second oscillation axis B by driving the driving sources 134a1, 134b1, 134a3, 134b3, 134a5, and 134b5 with the same waveform and driving sources 134a2, 134b2, 134a4, 134b4, 134a6, and 134b6 with the same waveform obtained by inverting the former in time series.

[0077] Driving wiring for applying a driving voltage to the upper electrode and the lower electrode of driving source 127a is connected to a predetermined terminal included in terminal group 135a provided on fixed frame 133. Driving wiring for applying a driving voltage to the upper electrode and the lower electrode of driving source 127b is connected to a predetermined terminal included in terminal group 135b provided on fixed frame 133.

[0078] Moreover, the driving wiring for applying a driving voltage to the upper electrode and the lower electrode of the driving source 134a is connected to a predetermined terminal included in the terminal group 135a provided on the fixed frame 133. Moreover, the driving wiring for applying a driving voltage to the upper electrode and the lower electrode of the driving source 134b is connected to a predetermined terminal included in the terminal group 135b provided on the fixed frame 133.

[0079] The light deflection unit 12 also has horizontal piezoelectric sensors 137a and 137b, which are horizontal oscillation angle sensors that detect the degree of horizontal inclination (horizontal oscillation angle) when the reflecting surface 121 is oscillating horizontally and are vibration sensors that detect the timing of launching the laser light. The horizontal piezoelectric sensors 137a and 137b are provided on the connecting beams 125a and 125b.

[0080] Furthermore, the optical deflection unit 12 has vertical piezoelectric sensors 136a and 136b, which are vertical oscillation angle sensors that detect the degree of inclination in the vertical direction (vertical oscillation angle) when the reflecting surface 121 is oscillating in the vertical direction, and which are vibration sensors that detect unnecessary vibration of the vertical beam to remove unnecessary vibration components from the drive signal. The vertical piezoelectric sensors 136a and 136b are provided on one of the vertical beams constituting the second drive beams 130a and 130b.

[0081] Such an optical deflection unit 12 can be manufactured by a semiconductor process using, for example, an SOI (Silicon On Insulator) substrate having a support layer, a buried oxide (BOX) layer, and an active layer.

[0082] In this embodiment, the first maximum swing angle α 1 is the second maximum swing angle α around the second swing axis B 2 For example, the first maximum deflection angle α 1 is ±12.0[deg], and the second maximum deflection angle α 2 is ±7.0[degrees]. Note that the first maximum deflection angle α 1 corresponds to the maximum swing angle α.

[0083] <Function of the inclination of the light-transmitting plate 3> Here, as described above, in a light deflection device equipped with a light-transmitting plate, a part of the light deflected by the light deflection unit may be reflected back to the light deflection unit without passing through the light-transmitting plate, and may be deflected again by the light deflection unit and included in the projected image. Also, a part of the light incident on the light deflection device may be reflected by the light-transmitting plate and included in the projected image. Hereinafter, the effect of the inclination of the light-transmitting plate 3 on the reflected light at such a light-transmitting plate 3 will be described.

[0084] 6 is a diagram for explaining an example of the incidence of laser light into the optical deflection device 20 and the emission of laser light from the optical deflection device 20. The incident laser light passes through the light-transmitting plate 3 and enters the optical deflection device 20. The emitted laser light passes through the light-transmitting plate 3 and exits from the optical deflection device 20.

[0085] In the example shown in FIG. 6, an incident laser beam enters the optical deflection device 20 and an outgoing laser beam exits the optical deflection device 20 along a plane including a first oscillation axis A along the Y axis.

[0086] 7 is a diagram for explaining an example of the effect of the inclination of the light transmitting plate 3 of the light deflection device 20. FIG 7 is a cross-sectional view of the light deflection device 20 taken along the cutting line SS in FIG.

[0087] 7, incident laser light L1 passes through the light-transmitting plate 3 and is incident on the reflecting surface 121 of the light deflection unit 12. After the incident laser light L1 is reflected by the reflecting surface 121, the outgoing laser light L2 passes through the light-transmitting plate 3 and is emitted.

[0088] The height h of the area where the incident laser light L1 incident on the reflecting surface 121 of the light deflecting unit 12 passes through the light transmitting plate 3 with respect to the mounting surface 111 1 is the height h of the area where the emitted laser light L2 deflected by the light deflection unit 12 passes through the light transmitting plate 3 with respect to the placement surface 111. 2 It is getting higher.

[0089] The primary reflected laser light R1 indicates the laser light obtained by reflecting the incident laser light L1 on the first surface 31 on the +Z direction side of the light-transmitting plate 3. The secondary reflected laser light R2 indicates the laser light obtained by reflecting the incident laser light L1 on the second surface 32 on the -Z direction side of the light-transmitting plate 3.

[0090] The tertiary reflected laser light R3 indicates a laser light that is emitted after the emitted laser light L2 is reflected by the second surface 32 of the light-transmitting plate 3, reflected again by the reflecting surface 121, and then transmitted through the light-transmitting plate 3. The fourth reflected laser light R4 indicates a laser light that is emitted after the emitted laser light L2 is reflected by the first surface 31 of the light-transmitting plate 3, reflected again by the reflecting surface 121, and then transmitted through the light-transmitting plate 3.

[0091] Here, the influence of reflected light, including that reflected by the light-transmitting plate 3 in the image projection device 100, will be described in detail.

[0092] The light intensity of the incident laser light L1 entering the optical deflection device 20 is set to 100% and the transmittance of the anti-reflection coatings applied to the first surface 31 and the second surface 32 of the light-transmitting plate 3 is set to 98%.

[0093] In this case, when the incident laser light L1 is transmitted through the first surface 31 and the second surface 32, and the outgoing laser light L2 is transmitted through the first surface 31 and the second surface 32, the difference is 0.98 4 =0.92, and the light intensity of the emitted laser light L2 becomes 92[%].

[0094] For example, when the emitted laser light L2 scans the surface 200 to draw an image 201 on the surface 200 with a resolution of 720P (1280×720 pixels), the light intensity of the emitted laser light L2 for drawing one pixel in one frame is 0.0001% (92 / (1280×720)). In other words, one pixel is drawn with a light intensity of 0.0001% of the light intensity of the incident laser light L1.

[0095] On the other hand, in the image projection device 100, when the primary reflected laser light R1 is in a state where it is included in the image 201 on the scanned surface 200, the primary reflected laser light R1 having 2[%] of the light intensity of the incident laser light L1 is included in the image 201. This primary reflected laser light R1 has a light intensity 20000 times that of the emitted laser light L2 which draws the image 201, and irradiates a predetermined location in the image 201 without moving.

[0096] In addition, when the secondary reflected laser light R2 is included in the image 201 on the scanned surface 200, the 2 × 0.02, secondary reflected laser light R2 with a light intensity of 0.019[%] of the incident laser light L1 is included in the image 201. This secondary reflected laser light R2 has a light intensity 190 times that of the emitted laser light L2 that renders the image 201, and irradiates a predetermined location in the image 201 without moving.

[0097] In addition, when the third reflected laser light R3 is included in the image 201 on the scanned surface 200, the 4Because of ×0.02, tertiary reflected laser light R3 having a light intensity of 0.018[%] of the incident laser light L1 is included in the image 201. This tertiary reflected laser light R3 has a light intensity 180 times that of the emitted laser light L2 that draws the image 201, and draws the same image as the image 201 at a position shifted from the image 201 on the scanned surface 200.

[0098] In addition, when the fourth reflected laser light R4 is included in the image 201 on the scanned surface 200, the 5 Because of ×0.02, the fourth reflected laser light R4 having a light intensity of 0.018[%] of the incident laser light L1 is included in the image 201. This fourth reflected laser light R4 has a light intensity 180 times that of the emitted laser light L2 that draws the image 201, and draws the same image as the image 201 at a position shifted from the image 201 on the scanned surface 200.

[0099] In this embodiment, the light-transmitting plate 3 is tilted with respect to the placement surface 111 so that the laser light reflected by the light-transmitting plate 3, such as the first reflected laser light R1 to the fourth reflected laser light R4, is not included in the image 201.

[0100] 7 indicates the inclination angle of the light-transmitting plate 3 with respect to the placement surface 111. The light-transmitting plate 3 is inclined at the inclination angle θ with respect to the placement surface 111 around an axis along the second oscillation axis B. Also, the second maximum deflection angle α 2 indicates the maximum swing angle around the second swing axis B corresponding to the axis along the X-axis.

[0101] In this embodiment, the inclination angle θ is determined so as to satisfy the condition expressed by the following formula. |θ|=2×α 2 +β 2 0<β 2 ≦90-2×α 2 However, β 1 and β 2 Each of the angles represents a selection angle that means an angle that can be appropriately selected. || represents an absolute value. The second maximum deflection angle α 2 and the inclination angle θ and the selection angle β 1 and β2 The unit is [degrees].

[0102] The inclination angle θ is the second maximum deflection angle α 2 If the inclination angle θ is set to be larger than the second maximum deflection angle α 2 If the reflected light R3 and the reflected light R4 are set to twice or more, the third reflected light R3 and the fourth reflected light R4 will not reach the scanned surface 200 and will not be included in the image 201.

[0103] Therefore, by determining the tilt angle θ so as to satisfy the above formula, it is possible to make the first reflected laser beam R1 to the fourth reflected laser beam R4 not be included in the image 201. In the example shown in FIG. 2 is 7.0[deg], and the selected angle β 2 is 4.0[deg]. The inclination angle θ is set to 18.0[deg] according to the above formula.

[0104] Next, Fig. 8 is a diagram for explaining the effect of the inclination of the light-transmitting plate 3a of the light deflection device 20a according to the comparative example. For ease of comparison with the light deflection device 20 according to the embodiment, the light deflection device 20a shown in Fig. 8 has the same configuration as the light deflection device 20, and differs from the light deflection device 20 only in the inclination angle of the light-transmitting plate 3a with respect to the placement surface 111 (reference surface).

[0105] Fig. 8 is a cross-sectional view of the optical deflection device 20a taken along a line corresponding to the line SS in Fig. 6. In Fig. 8, the same part numbers as those in the optical deflection device 20 are used for the components of the optical deflection device 20a.

[0106] 8 indicates the inclination angle of the light transmitting plate 3a with respect to the placement surface 111. 2 ' indicates the maximum swing angle around the second swing axis B.

[0107] The tilt angle θ' is 11.0 degrees, and the maximum swing angle is 7.0 degrees. The tilt angle θ' is the second maximum swing angle α 2Since the reflected light R1 and the reflected light R2 are larger than the reflected light R1, the primary reflected light R1 and the secondary reflected light R2 are not included in the image 201.

[0108] However, the tilt angle θ' is smaller than the second maximum deflection angle α 2 Since the angle is smaller than 14 degrees, which is twice the angle of the reflected light, the third reflected light R3 and the fourth reflected light R4 are emitted in a direction close to the emitted laser light L2 and are included in the image 201. As a result, an image identical to the image 201 is projected on the scanned surface 200 at a position slightly shifted from the image 201, resulting in multiple images or moire fringes, in which multiple images are visually overlapped.

[0109] <Effects of the optical deflection device 20> As described above, the optical deflection device 20 of this embodiment has an optical deflection unit 12 that deflects laser light incident on the reflecting surface 121 by oscillating the reflecting surface 121 around a first oscillation axis A (first axis) and around a second oscillation axis B (second axis), and a light transmitting plate 3 that transmits the laser light deflected by the optical deflection unit 12.

[0110] In this embodiment, the inclination angle of the light transmitting plate 3 with respect to the placement surface 111 (reference surface) is set to the second maximum deflection angle α 2 This makes it possible for the primary reflected light R1, secondary reflected light R2, tertiary reflected light R3, and quaternary reflected light R4 resulting from reflection at the light-transmitting plate 3 to not reach the scanned surface 200. As a result, it is possible to prevent the reflected light at the light-transmitting plate 3 from being included in the projected image. This makes it possible to ensure high quality of the image projected onto the scanned surface 200.

[0111] In the above-described embodiment, the light emitting unit 10 causes the laser light to enter the inside of the light deflection device 20 from the outside of the light-transmitting plate 3, but the present invention is not limited to this. This embodiment is also applicable to a configuration in which the light emitting unit 10 is provided inside the light deflection device 20 and the laser light is incident on the reflection surface 121 without passing through the light-transmitting plate 3.

[0112] In this embodiment, the light deflection unit 12 deflects the laser light incident on the reflecting surface 121 in two intersecting directions by swinging the reflecting surface 121 around both the first swing axis A and the second swing axis B intersecting the first swing axis A. Then, a first maximum deflection angle α of the reflecting surface 121 around the first swing axis A with respect to the mounting surface 111 is 1 is the second maximum swing angle α of the reflecting surface 121 relative to the mounting surface 111 around the second swing axis B. 2 More significantly, the light-transmitting plate 3 is tilted around an axis along the second oscillation axis B.

[0113] For example, when the light transmitting plate 3 is tilted around the first oscillation axis A, the first maximum oscillation angle α 1 is 12.0 degrees, so the light-transmitting plate 3 is set to 28.0 degrees (β 1 In contrast, when tilting around the second oscillation axis B, the inclination angle of the light-transmitting plate 3 can be 18.0 degrees. Since the inclination angle of the light-transmitting plate 3 is smaller, at least one of the package 11 and the lid 2 can be made smaller. As a result, the light deflection device 20 can be made smaller.

[0114] In this embodiment, a configuration in which the first oscillation axis A is aligned along the Y direction has been exemplified, but the present invention is not limited to this, and any configuration may be used as long as the light-transmitting plate 3 is tilted around an axis that provides a smaller maximum deflection angle of the reflecting surface 121. In other words, the first oscillation axis A may face in any direction. For example, the first oscillation axis A may be configured to be aligned along the X direction. Even with this configuration, at least one of the package 11 or the lid 2 can be made smaller in size since the tilt angle of the light-transmitting plate 3 is smaller, and the light deflection device 20 can be made smaller in size.

[0115] However, the first maximum swing angle α of the reflecting surface 121 with respect to the mounting surface 111 around the first swing axis A 1 The second maximum swing angle α of the reflecting surface 121 with respect to the mounting surface 111 about the second swing axis B is 2 In the case where the light-transmitting plate 3 is larger than the first oscillation axis B, the light-transmitting plate 3 is not limited to being tilted around an axis along the second oscillation axis B. For example, the light-transmitting plate 3 may be tilted around an axis along the first oscillation axis A.

[0116] In this embodiment, the height h of the region through which the laser light incident on the reflecting surface 121 passes through the light transmitting plate 3 with respect to the mounting surface 111 is 1 is the height h of the area through which the laser light deflected by the light deflection unit 12 passes through the light transmitting plate 3 with respect to the mounting surface 111. 2 With this configuration, at least one of the package 11 and the lid 2 can be made compact, and the optical deflection device 20 can be made compact.

[0117] <Modifications of the optical deflection device 20> Here, since the optical deflection device 20 can be modified in various ways, the modified examples will be described below.

[0118] (Modification of the light deflection unit) First, a modified example of the optical deflection unit will be described. In the above-mentioned embodiment, the configuration of the optical deflection unit 12 that deflects the laser light in two intersecting directions is exemplified, but the present invention is not limited to this. For example, the optical deflection device 20 may include an optical deflection unit that deflects the light incident on the reflecting surface in one direction by swinging the reflecting surface around one swing axis.

[0119] 9 is a perspective view for explaining another first example of the light deflection unit. The light deflection unit 12a includes a reflecting surface 121a, and deflects the laser light reflected by the reflecting surface 121a around the second oscillation axis B by oscillating the reflecting surface 121a around the second oscillation axis B. The light deflection unit 12a is, for example, a MEMS mirror that drives the reflecting surface 121a by a piezoelectric element.

[0120] As shown in FIG. 9, the optical deflection unit 12a has a reflecting surface 121a, a supporting unit 123a, connecting units 131aa and 131ba, second actuation beams 130aa and 130ba, actuation sources 134aa and 134ba, fixed frame connecting units 132aa and 132ba, and a fixed frame 133a.

[0121] The optical deflection unit 12a is provided with a support unit 123a including a reflecting surface 121a instead of the movable frame 122 of the optical deflection unit 12, and the function of each component is the same as the function of the corresponding component in the optical deflection unit 12. Therefore, a duplicated description will be omitted here.

[0122] 10 is a perspective view illustrating another second example of the light deflection unit. The light deflection unit 12b includes a reflecting surface 121b, and deflects the laser light incident on the reflecting surface 121b about the first oscillation axis A by oscillating the reflecting surface 121b about the first oscillation axis A. The light deflection unit 12b is, for example, a MEMS mirror that drives the reflecting surface 121b by a piezoelectric element.

[0123] As shown in FIG. 10, the optical deflection unit 12b has a reflecting surface 121b, a movable frame 122b, a support unit 123b, torsion beams 124ab and 124bb, connecting beams 125ab and 125bb, first actuation beams 126ab and 126bb, and actuation sources 127ab and 127bb.

[0124] The optical deflection unit 12b is obtained by removing components such as the second actuation beams 130a and 130b connected to the movable frame 122 of the optical deflection unit 12, and the function of each component is the same as the function of the corresponding component in the optical deflection unit 12. Therefore, a duplicated description will be omitted here.

[0125] The optical deflection device 20 may also include an optical deflection unit that swings the reflecting surface around one swing axis as shown in Figures 9 and 10. In this case, too, by setting the inclination angle of the light-transmitting plate 3 with respect to the mounting surface 111 to be at least twice the maximum swing angle of the reflecting surface 121 with respect to the mounting surface 111, it is possible to obtain the same effect as the optical deflection device 20 described above.

[0126] (Modification of the direction in which the light-transmitting plate 3 is tilted) Next, modified examples of the direction in which the light-transmitting plate 3 is tilted will be described. In the above-described embodiment, the light-transmitting plate 3 is tilted around the axis along the second oscillation axis B, but the present invention is not limited to this. For example, when the first maximum deflection angle α 1The light transmitting plate 3 may be tilted around an axis along the first oscillation axis A at an angle of inclination that is twice or more of the above.

[0127] Furthermore, the light-transmitting plate 3 may be tilted around an axis other than the axis along each of the first oscillation axis A and the second oscillation axis B. In other words, the light-transmitting plate 3 may be tilted around an axis included in a plane parallel to the placement surface 111 and non-parallel to the first oscillation axis A and the second oscillation axis B.

[0128] Here, Fig. 11 is a diagram for explaining another example of the inclination of the light-transmitting plate 3. In Fig. 11, a plane 111A represents a plane including the first oscillation axis A and the second oscillation axis B, and a plane 111B represents a plane corresponding to the placement surface 111 as a reference surface. A plane 111C represents a plane parallel to the placement surface 111.

[0129] The tilt axis is an axis included in the plane 111C (a plane parallel to the reference plane) and is an axis non-parallel to the first oscillation axis A and the second oscillation axis B. The light transmitting plate 3 may be tilted around this tilt axis .

[0130] Incidentally, the tilt axis 35 may be an axis facing in any direction among 360 degrees around an orthogonal axis D that is perpendicular to each of the planes 111A, 111B, and 111C. In addition, the tilt axis 35 does not necessarily have to be an axis passing through the orthogonal axis D.

[0131] When the light-transmitting plate 3 is tilted around the tilt axis 35, the tilt angle of the light-transmitting plate 3 around the first oscillation axis A is set to θ 1 The inclination angle of the light transmitting plate 3 about the second oscillation axis B is θ 2 In this case, it is preferable to satisfy the condition expressed by the following formula: |θ 1 |=2×α 1 +β 1 |θ 2 |=2×α 2 +β 2 0<β 1 ≦90-2×α 1 0<β 2 ≦90-2×α2 In addition, β 1 and β 2 respectively represent the selected angles, and α 1 , α 2 , θ 1 , θ 2 , β 1 , β 2 The unit of is [degrees]. By satisfying this condition, it is possible to obtain the same effect as the optical deflection device 20 described above.

[0132] Furthermore, when the optical deflection device 20 has the optical deflection unit 12 that swings the reflecting surface 121 around one swing axis, it is preferable to tilt the light-transmitting plate 3 around a tilt axis 35 that is included in a plane 111C parallel to the mounting surface 111 and is an axis that is not parallel to the swing axis. This allows at least one of the package 11 and the lid 2 to be made smaller.

[0133] (Modification of the Incident Height of the Laser Light L1 to the Light-Transmitting Plate 3) In the above-described embodiment, the height h of the area through which the incident laser light L1 passes through the light transmitting plate 3 with respect to the placement surface 111 is 1 The height h of the area through which the emitted laser light L2 passes through the light transmitting plate 3 with respect to the mounting surface 111 2 Although a taller configuration is illustrated, this is not limiting.

[0134] For example, the height of the transmitting region of the light transmitting plate 3 relative to the placement surface 111 may be higher for the outgoing laser light L2 than for the incoming laser light L1, or may be equal for the incoming laser light L1 and the outgoing laser light L2.

[0135] (Examples of combinations of incident height and inclination of incident laser light L1 on light-transmitting plate 3) Next, various combinations of the incidence height of the laser light L1 incident on the light transmitting plate 3 and the inclination of the light transmitting plate 3 will be described with reference to FIGS.

[0136] First, Fig. 12 shows a first example, where Fig. 12(a) is a perspective view of the optical deflection device 20, and Fig. 12(b) is a cross-sectional view along the line TT in Fig. 12(a). In Fig. 12, an incident laser beam L1 enters the optical deflection device 20 along a plane including a second oscillation axis B along the X-axis, and an outgoing laser beam exits the optical deflection device 20. The light-transmitting plate 3 is tilted around the second oscillation axis B along the X-axis.

[0137] In this case, the inclination angle θ of the light transmitting plate 3 is set to the second maximum deflection angle α of the reflecting surface 121. 2 The inclination angle θ of the light transmitting plate 3 is preferably equal to or greater than the second maximum deflection angle α 2 Select angle β twice 2 It is particularly preferable that the value be equal to the value obtained by adding 2.0 [degrees] as the angle.

[0138] Next, Fig. 13 shows a second example, where Fig. 13(a) is a perspective view of the optical deflection device 20, and Fig. 13(b) is a cross-sectional view along the UU line in Fig. 13(a). In Fig. 13, an incident laser beam L1 enters the optical deflection device 20 along a plane including a first oscillation axis A along the X-axis, and an outgoing laser beam exits the optical deflection device 20. Also, the light transmitting plate 3 is tilted around the first oscillation axis A along the Y-axis.

[0139] In this case, the inclination angle θ of the light transmitting plate 3 is set to the first maximum deflection angle α 1 The inclination angle θ of the light transmitting plate 3 is preferably equal to or greater than the first maximum deflection angle α 1 Select angle β twice 2 It is particularly preferable that the value be equal to the value obtained by adding 2.0 [degrees] as the angle.

[0140] Next, Fig. 14 shows a third example, where Fig. 14(a) is a perspective view of the optical deflection device 20, and Fig. 14(b) is a cross-sectional view along the VV cutting line in Fig. 14(a). In Fig. 14, an incident laser beam L1 enters the optical deflection device 20 along a plane including a first oscillation axis A along the Y axis, and an outgoing laser beam exits the optical deflection device 20. The light transmitting plate 3 is tilted around the first oscillation axis A along the Y axis.

[0141] In this case, the inclination angle θ of the light transmitting plate 3 is set to the first maximum deflection angle α 1 The inclination angle θ of the light transmitting plate 3 is preferably equal to or greater than the first maximum deflection angle α 1 Select angle β twice 2 It is particularly preferable that the value be equal to the value obtained by adding 2.0 [degrees] as the angle.

[0142] Although the embodiments have been described above, the present invention is not limited to the above specifically disclosed embodiments, and various modifications and changes are possible without departing from the scope of the claims.

[0143] In addition, all numbers such as ordinal numbers and quantities used in the description of the embodiments are provided as examples to specifically explain the technology of the present invention, and the present invention is not limited to the exemplified numbers. In addition, the connection relationships between the components are provided as examples to specifically explain the technology of the present invention, and the connection relationships that realize the functions of the present invention are not limited to these. [Explanation of symbols]

[0144] 1...optical deflection unit, 11...package, 111...mounting surface (an example of a reference surface), 111A, 111B, 111C...flat surface, 12...optical deflection section, 121...reflecting surface, 122...movable frame, 123...support section, 124a, 124b...torsion beams, 125a, 125b...connecting beams, 126a, 126b...first drive beams, 127a, 127b...drive source, 128...slits, 130a, 130b...second drive beams, 131a, 131b...movable frame connection sections, 132a, 132b...fixed frame connection sections, 133...fixed frame, 134a, 134b...fixed frame connection sections, 134a, 134b...fixed frame connection sections, 134b, 134c ... b...driving source, 135a, 135b...terminal group, 136a, 136b...vertical piezoelectric sensor, 137a, 137b...horizontal piezoelectric sensor, 2...lid, 3...light-transmitting plate, 31...first surface, 32...second surface, 35...tilt axis, 10...light-emitting unit, 20...light deflection device, 30...control unit, 200...scanned surface, 201...image, A...first oscillation axis (an example of an oscillation axis, an example of a first axis), B...second oscillation axis (an example of a second axis), L1...incident laser light, L2...outgoing laser light, R3...third reflected laser light, R4...fourth reflected laser light, h 1 , h 2 Height, α Maximum deflection angle, α 1 ...1st maximum deflection angle, α 2 ...Second maximum deflection angle, β 1 , β 2 ...Selected angle, θ 1 , θ 2 Tilt angle

Claims

1. a light deflection unit that deflects light incident on the reflecting surface by swinging the reflecting surface around a swing axis; a light-transmitting plate that transmits the light deflected by the light deflection unit and projects an image onto a surface to be scanned, the light deflection unit oscillates the reflection surface around both a first axis and a second axis intersecting the first axis, thereby deflecting light incident on the reflection surface in two intersecting directions; a first maximum deflection angle of the reflecting surface about the first axis with respect to a reference surface is greater than a second maximum deflection angle of the reflecting surface about the second axis with respect to the reference surface; an inclination angle of the light-transmitting plate with respect to the reference surface that is greater than or equal to twice the second maximum deflection angle of the reflecting surface with respect to the reference surface, and is determined so as to prevent light that is reflected by the surface of the light-transmitting plate, returns to the light deflection unit, and is reflected by the reflecting surface to pass through the light-transmitting plate from reaching a surface to be scanned.

2. 2. The optical deflection device according to claim 1, wherein the light transmitting plate is tilted about an axis that is included in a plane parallel to the reference plane and is non-parallel to the first axis and the second axis.

3. The optical deflection device according to claim 1 , wherein the light-transmitting plate is tilted about an axis along the second axis.

4. The optical deflection device according to claim 1 , wherein the light transmitting plate is tilted about an axis along the first axis.

5. the light is incident on the reflecting surface after passing through the light-transmitting plate, 5. The optical deflection device according to claim 1, wherein a height of an area where the light incident on the reflecting surface passes through the light-transmitting plate relative to the reference plane is greater than a height of an area where the light deflected by the optical deflection unit passes through the light-transmitting plate relative to the reference plane.

6. A light emitting unit that emits light; The optical deflection device according to any one of claims 1 to 5, An image projection device that projects an image on a surface to be scanned by scanning the light with the light deflection device.

Images