Projection device

Abstract

The present invention provides a projection device. The outgoing light of a laser light source (101) is divided by a prism (102) into two light beams (130) corresponding to the outgoing light from an inclined surface (104) and an inclined surface (105), and a light beam (131). The light beam (130) and the light beam (131) are diffused by a diffusion plate (106) and a diffusion plate (111), thereby becoming a light beam (132) and a light beam (133). By overlapping the light beam (132) and the light beam (133), a radiation distribution with a large angle and high light intensity can be obtained.

Description

Technical Field

[0001] The present invention relates to a projection device for distance measurement. Background Art

[0002] Conventionally, as distance measurement methods, a phase difference detection method of amplitude-modulating light from a light source and measuring the phase difference between the reflected light from the object to be measured and the light source, and a TOF (Time Of Flight) method of measuring the distance by irradiating light of an extremely short pulse and measuring the arrival time of the reflected light from the object to be measured are known.

[0003] Here, if it is desired to extend the measurable distance and improve the measurement accuracy, in order to obtain small-sized, high-output, and high-frequency modulation or a very short pulse waveform, it is necessary to use a semiconductor laser as the light source.

[0004] Regarding the use of a laser light source, from the viewpoint of safety for the human body and eyes, it is regulated by JIS-C6802 in Japan. In particular, when there is a possibility that light enters a person's eyes, generally, it is necessary to satisfy the conditions of Class 1.

[0005] Here, in order to satisfy the conditions of Class 1 and increase the output of the laser light source, it is necessary to increase the beam diameter of the laser in a diffuser plate disposed on the exit surface of the projection device.

[0006] Specifically, when the beam diameter on the exit surface of the projection device is small, when a person observes the projection device, the light source image formed on the retina of the eye also becomes small, and the light concentration becomes high, which easily causes damage to the eyes. To prevent this, by increasing the beam diameter of the exit surface of the projection device, the light source image formed on the retina can be increased. As a result, the eyes are not damaged, and the maximum value of the light output of the laser light source can be increased.

[0007] However, as a conventional laser projection device, there is a laser projection device having a structure in which a diffuser plate is disposed on a window of an exit portion of a semiconductor laser (for example, refer to Patent Document 1).

[0008] In the invention of Patent Document 1, the emitted light from the laser light source is diffused and magnified by a concave lens, and the light is projected onto the diffuser plate. In the diffuser plate, the light is diffused isotropically. By using a concave lens, the beam diameter in the diffuser plate is made larger.

[0009] Here, the beam diameter of the laser light source is very small, on the order of several μm, but by using a concave lens and a diffuser plate, a beam diameter much larger than the beam diameter on the exit surface of the laser light source is formed on the diffuser plate.

[0010] Accordingly, when a person observes a laser, the image of the light source formed on the retina of the eye becomes larger, so that the eye is not damaged and the upper limit of the laser output can be increased.

[0011] Prior art documents

[0012] Patent documents

[0013] Patent Document 1: Japanese Patent Laid-Open No. 9-307174 Summary of the Invention

[0014] A projection device according to one aspect of the present invention includes: a triangular prism having a first surface, a second surface, and a third surface; a light source that emits light to the first surface of the prism; and two diffusion plates disposed opposite to the second surface and the third surface of the prism, respectively, and an apex angle formed by the second surface and the third surface of the prism is 5° or more and 90° or less. Brief Description of the Drawings

[0015] Figure 1 It is a schematic diagram showing the structure of the laser projection device according to the present embodiment.

[0016] Figure 2 It is a cross-sectional view showing a partial enlargement of the structure of the diffusion plate.

[0017] Figure 3 It is a diagram showing the light rays of the laser projection device.

[0018] Figure 4 It is a diagram showing the light diffusion caused by refraction in the diffusion plate.

[0019] Figure 5A It is a diagram showing the radiation angle distribution of the light emitted from the inclined surface of the prism.

[0020] Figure 5B It is a diagram showing the radiation angle distribution of the light emitted from the diffusion plate.

[0021] Figure 5C It is a diagram showing the radiation angle distribution as a laser projection device when the light beams of the diffusion plates are overlapped.

[0022] Description of the Reference Numerals

[0023] 100 Laser projection device

[0024] 101 Laser light source

[0025] 102 Prism

[0026] 103 Bottom surface (first surface)

[0027] 104 Inclined surface (second surface)

[0028] 105 Inclined surface (the third surface)

[0029] 106 Diffusion plate

[0030] 108 Groove portion

[0031] 109 Concave portion

[0032] 110 Convex portion

[0033] 111 Diffusion plate

[0034] 112 Transparent housing Detailed implementation mode

[0035] In the prior invention, since the outgoing light of the laser light source is expanded by a concave lens and irradiated onto the diffusion plate, in order to increase the apparent beam diameter of the laser light source, it is necessary to make the diffusivity of the diffusion plate very high.

[0036] Specifically, in the central portion of the diffusion plate, light is incident on the incident surface of the diffusion plate substantially perpendicularly, but in the peripheral portion, it is incident on the incident surface of the diffusion plate obliquely. Therefore, in order to emit the same diffused light in the central portion and the peripheral portion of the diffusion plate, it is necessary to enhance the diffusivity to the extent that it does not depend on the angle of the incident light.

[0037] In addition, if the apparent beam diameter of the laser light source on the diffusion plate is small, the brightness of the light source will be high, and when a person observes the projection device, it will cause damage to the eyes. Therefore, in order to ensure the laser safety of the projection device, it is necessary to use a diffusion plate with very high diffusivity to increase the apparent beam diameter on the surface of the diffusion plate.

[0038] However, in a general frosted glass-like diffusion plate, light diffusion is performed by multiple reflections of light in the frosted glass portion. Therefore, if the light diffusivity is increased, the proportion of the light returning from the diffusion surface to the laser light source side will become large, and the light utilization efficiency will be greatly reduced.

[0039] In addition, the diffusion characteristics of a diffusion plate with high diffusivity are generally Lambert diffusion, and the light in the inclined direction becomes weak. Furthermore, since it is a flat diffusion surface, there is a problem that light diffusion of more than 180° cannot be performed.

[0040] The present invention has been completed in view of the above aspects, and its object is to provide a projection device in which light loss in the diffusion plate is small and light with a uniform and large emission angle can be emitted.

[0041] Hereinafter, embodiments of the present invention will be described based on the drawings. In addition, the description of the following preferred embodiments is essentially only illustrative, and the intention is not to limit the present invention, its application object, or its use.

[0042] Figure 1 is a schematic diagram of the laser projection device according to this embodiment. In Figure 1 , the right direction of the paper surface is set as the X-axis, the upward direction is set as the Y-axis, and the depth direction of the paper surface is set as the Z-axis.

[0043] As Figure 1 shown, the laser projection device 100 includes a laser light source 101, a prism 102, a diffusion plate 106 and a diffusion plate 111, and a transparent housing 112.

[0044] The laser light source 101 emits light in the positive X-axis direction. The distribution of the emitted light has a center of the radial distribution parallel to the X-axis and a radial distribution close to the Gaussian distribution. The divergence angle of the laser light source 101 is preferably 5° or more and 40° or less in terms of the full angle at half maximum. If possible, it is preferably 30° or less.

[0045] The wavelength of the laser light source 101 is a near-infrared monochromatic wavelength and is not perceived by the human eye when emitting light. The laser light source 101 has a plurality of laser light-emitting elements (not shown) arranged closely in the YZ plane. By arranging and configuring a plurality of laser light-emitting elements, the spatial interference can be reduced and the speckle noise can be lowered.

[0046] In addition, by using a laser as the light source, the responsiveness can be improved compared with an LED, and a pulsed light with a short emission time can be formed. Thus, even if the average energy is the same, by increasing the peak light intensity, in distance measurement or the like, it is possible to irradiate a distant object for measurement.

[0047] The prism 102 has a triangular cross-section in the XY plane and is an extruded shape with a fixed cross-sectional shape in the Z-axis direction. That is, the side of the prism 102 including the vertex of the triangle is parallel to the Z-axis direction of any apex portion.

[0048] The bottom surface 103 of the prism 102 is arranged to face the laser light source 101 and is parallel to the YZ plane. The apex angle θ formed by the inclined surfaces 104 and 105 of the prism 102 is 90° or less and is set according to the angle of total reflection of the light from the laser light source 101. In addition, if the apex angle θ is too small, the intensity is insufficient and it is easily damaged, so it is preferably 5° or more.

[0049] The prism 102 is transparent at the wavelength of the laser light source 101, and the material can be, for example, a resin such as polycarbonate or propylene, or glass.

[0050] The line connecting the center position of the bottom surface of the prism 102 and the vertex 113 of the prism 102 is arranged with a slight deviation from the light-emitting center of the laser light source 101.

[0051] The diffuser plate 106 is composed of a thin flat member. The diffuser plate 106 is arranged to face the inclined surface 104 of the prism 102. The groove portion 108 of the diffuser plate 106 is located on the side of the prism 102, and the opposite surface of the groove portion 108 is the flat portion 107.

[0052] The diffuser plate 111 is the same diffuser plate as the diffuser plate 106, and is arranged to face the inclined surface 105 of the prism 102. The groove portion of the diffuser plate 111 is located on the side of the prism 102.

[0053] The diffuser plate 106 and the diffuser plate 111 are transparent at the wavelength of the laser light source 101. The material can be, for example, a resin such as polycarbonate or propylene, or glass.

[0054] The diffuser plate 106 and the diffuser plate 111 are arranged with a specified gap d therebetween. The interval of the gap d is at least 0.05 mm or more. By providing the gap d, the generation of debris and the risk of breakage due to the contact between the diffuser plate 106 and the diffuser plate 111 can be reduced.

[0055] The optical quantity center line 140 indicates the direction in which the light quantity of the light emitted from the prism 102 has the maximum radiation distribution. The surface normal line 141 of the diffuser plate 106 is arranged to deviate clockwise by an angle φ around the Z axis with respect to the optical quantity center line 140. The angle φ is set to be about 1 / 2 of the divergence angle of the laser light source 101.

[0056] The cross-sectional shape of the transparent housing 112 in the XY plane is formed in a triangular shape. The surfaces of the transparent housing 112 facing the diffuser plate 106 and the surfaces of the transparent housing 112 facing the diffuser plate 111 are substantially parallel.

[0057] Figure 2 is a magnified view of the portion enclosed by the imaginary circle A shown in Figure 1 . As shown in Figure 2 , the concave portion 109 and the convex portion 110 of the groove portion 108 of the diffuser plate 106 are arranged adjacent to each other, and the combination of the concave portion 109 and the convex portion 110 forms a shape that repeats with a period p.

[0058] The groove portion 108 is an extrusion shape with a fixed cross-sectional shape in the Z-axis direction. That is, the side including the vertex of the triangular shape is parallel to the groove direction of the groove portion 108 of any apex portion.

[0059] The concave portion 109 and the convex portion 110 are aspherical shapes, the inclination angles of the portions where the concave portion 109 and the convex portion 110 are in contact are the same, and the concave portion 109 and the convex portion 110 are smoothly joined. The shape after rotating the concave portion 109 by 180 degrees around the Z-axis center is a shape similar to the convex portion 110. In the XY plane, the line 145 passing through the connecting portion of the concave portion 109 and the convex portion 110 is perpendicular to the normal direction of the groove portion 108. In addition, the groove shape of the diffuser plate 111 is the same as that of the diffuser plate 106.

[0060] Hereinafter, the operation of the laser projection device 100 will be described. As Figure 3 shown, the emitted light 120 of the laser light source 101 enters and is refracted from the bottom surface 103 of the prism 102, becoming the light beam 121. The apex angle θ of the prism 102 is set to be less than 90° and total reflection occurs on the inclined surface 105. Therefore, most of the light of the light beam 121 is totally reflected by the inclined surface 105 and enters the inclined surface 104 opposite to the inclined surface 105.

[0061] The light beam 121 enters at an angle close to the normal direction of the inclined surface 104. Therefore, most of the light passes through the inclined surface 104 and exits from the prism 102. The light beam 121 exiting from the inclined surface 104 of the prism 102 enters the groove portion 108 of the diffusion plate 106.

[0062] Figure 4 is a magnified view of the portion enclosed by the imaginary circle B shown in Figure 3 As shown, the groove portion 108 is composed of a concave portion 109 and a convex portion 110. The light beam 122 entering the concave portion 109 is diffused by the concave lens effect. The light beam 123 entering the convex portion 110 is temporarily condensed and then diffused. Figure 4 As shown, the groove portion 108 is composed of a concave portion 109 and a convex portion 110. The light beam 122 entering the concave portion 109 is diffused by the concave lens effect. The light beam 123 entering the convex portion 110 is temporarily condensed and then diffused.

[0063] The light diffused in the groove portion 108 of the diffusion plate 106 is refracted and exits from the flat surface portion 107 of the diffusion plate 106. The refractive index of the diffusion plate 106 is larger than that of air. Therefore, the divergence angle of the light exiting from the diffusion plate 106 further increases. Thus, the light beam 121 entering the groove portion 108 provided with the concave portion 109 and the convex portion 110 is optically diffused by the refraction effect. Similarly, the light that is totally reflected by the inclined surface 104 of the prism 102, passes through the inclined surface 105, and is diffused by the diffusion plate 111.

[0064] Figures 5A to 5C is a diagram showing the emission angle distribution of the emitted light from the laser projection device 100 on the Figure 1 XY plane. Regarding the angle, the X-axis passing through the vertex 113 of the prism 102 is set to 0 degrees, and with respect to the Z-axis when observing from the negative direction to the positive direction of the Z-axis, the clockwise direction is set as positive and the counterclockwise direction is set as negative.

[0065] Figure 5A is a diagram showing the emission angle distribution of the emitted light from the inclined surface 104 and the inclined surface 105 of the prism 102. As Figure 5A shown, the emitted light of the laser light source 101 is split into two light beams 130 and 131 corresponding to the emitted light from the inclined surface 104 and the inclined surface 105 through the prism 102.

[0066] Figure 5BIt is a diagram showing the emission angle distribution of the emitted light of the diffusion plates 106 and 111. The light emitted from the inclined surfaces 104 and 105 of the prism 102 is diffused by the diffusion plates 106 and 111, thereby becoming the light beams 132 and 133.

[0067] The light beam 132, which is the light diffused by the diffusion plate 106, has an expansion in the negative direction of the emission angle distribution, but the expansion angle of the diffusion plate 106 is set so as to slightly cross over to the positive direction. Similarly, the light beam 133, which is the light diffused by the diffusion plate 111, has an expansion in the positive direction of the emission angle distribution, but the expansion angle of the diffusion plate 111 is set so as to slightly cross over to the negative direction.

[0068] The light intensity on the negative direction side of the emission angle distribution of the light beam 134 of the emitted light from the diffusion plate 106 becomes higher, and the light intensity in the direction of the angle 0° becomes lower (refer to Figure 5C ). This is caused by the following situation, that is, in Figure 2 , the light quantity center line 140 of the emitted light of the prism 102 is incident on the surface normal line 141 of the groove portion 108 of the diffusion plate 106 at an angle φ in the XY plane.

[0069] By making the light quantity center line 140 of the emitted light of the prism 102 incident on the groove portion 108 at an angle φ, the incident angle with respect to the inclined surface 146 of the groove portion 108 becomes smaller, and thus the change in the light ray angle due to refraction becomes smaller. That is, the diffusion in the diffusion plate 106 becomes smaller. The refracted light at the inclined surface 146 of the groove portion 108 is the light diffused in the negative direction of the emission angle distribution, so the expansion of the angle in the negative direction becomes smaller (refer to the reference numeral 150 in Figure 5B ).

[0070] On the other hand, with respect to the inclined surface 147, the incident angle becomes larger, and thus the change in the light ray angle due to refraction becomes larger. That is, the diffusion in the diffusion plate 106 becomes larger. The refracted light at the inclined surface 147 of the groove portion 108 is the light diffused in the positive direction side of the emission angle distribution, so the expansion of the angle in the positive direction side becomes larger (refer to the reference numeral 151 in Figure 5B ).

[0071] If the light quantity center line 140 is inclined at an angle φ with respect to the surface normal line 141, the light quantity toward the inclined surface 146 is more than that toward the inclined surface 147, and the light diffusion becomes smaller. Therefore, in the emission angle distribution, the light intensity in the negative direction becomes larger. Therefore, the light intensity in the negative direction of the emission angle distribution of the emitted light of the diffusion plate 106 becomes stronger. In addition, in the emitted light from the diffusion plate 111, the light intensity on the positive direction side becomes stronger as well.

[0072] Figure 5CThis is the emission angle distribution of the laser projection device 100 when the light beam 132 of the diffusion plate 106 overlaps with the light beam 133 of the diffusion plate 111. The light beam 132 diffused from the diffusion plate 106 is set to expand not only in the negative angle direction but also, in part, in the positive angle direction (see Figure 5B ). Similarly, the diffused light beam 133 from the diffusion plate 111 is set to expand not only in the positive angle direction but also, in part, in the negative angle direction (see Figure 5B ).

[0073] Therefore, as shown in Figure 5C , by overlapping the light beam 132 and the light beam 133, a radiation distribution such as the light beam 134 can be obtained, with a slightly lower light quantity near 0° and high light intensities in the positive and negative directions.

[0074] With such a radiation distribution, it is advantageous when observing the positive and negative directions, i.e., the peripheral portions, from the 0° direction, which is the front direction of the laser projection device 100. By setting the expansion angles generated by the diffusion of the diffusion plate 106 and the diffusion plate 111 to 90° or more respectively, the combined expansion angle can be set to 180° or more.

[0075] On the other hand, the emission distribution in the XZ plane maintains the expansion angle of the laser light source 101 unchanged. In the case where the laser projection device 100 is mounted on a motor vehicle or the like, by setting the XZ plane to the vertical direction and the XY plane to the horizontal direction, light is not expanded much in the vertical direction but is expanded in the horizontal plane, thereby enabling efficient light irradiation.

[0076] However, when calculating the laser class of the laser light source 101, the beam diameter in the diffusion plate of the projection optical system interferes with the laser class calculation. In the present embodiment, the light is split into two by the prism 102 and each is diffused, so, apparently, the laser light source 101 is divided into two, and the upper limit of the laser light source output that becomes laser class 1 can be increased in the laser class calculation.

[0077] The diffusion plate 106 and the diffusion plate 111 can be manufactured by injection molding using a mold. In the present embodiment, the groove portions 108 of the diffusion plate 106 and the diffusion plate 111 are formed in a smooth curve shape as an extrusion shape. Therefore, for example, a mold can be easily fabricated by short-time machining through forming, and the diffusion plates can be inexpensively manufactured by injection molding. In addition, they are not easily affected by wear in the manufacturing process of the diffusion plate 106 and the diffusion plate 111 and deformation caused by poor transfer during forming.

[0078] In addition, the groove portions 108 of the diffusion plate 106 and the diffusion plate 111 are formed as smooth curves. Therefore, for example, the tilt angle does not increase locally at the edges or the like, and unwanted reflections and stray light near the edges are not generated. In addition, unexpected diffusion expansion due to wear of the edge portion is not formed, and the light efficiency of the diffusion plate is not easily reduced.

[0079] The diffusion plate 106 and the diffusion plate 111 are arranged with a gap d therebetween. However, the light from the laser light source 101 is split into two by the prism 102 and becomes light with an angle. Therefore, almost no light in the 0° direction is generated from the light emitted from the prism 102 (refer to Figure 5A ). Therefore, almost no leakage light is generated from the gap d between the diffusion plate 106 and the diffusion plate 111.

[0080] However, generally speaking, if an error occurs during assembly, it is difficult to align the radiation distribution center of the laser light source 101 with the axis of symmetry of the prism 102.

[0081] In contrast, in the present embodiment, the radiation distribution of the laser light source 101 is a Gaussian distribution and has an expansion of at least 5° or more in terms of the full angle at half maximum, and the radiation distributions of the diffusion plate 106 and the diffusion plate 111 overlap at an angle of 0°.

[0082] Therefore, even if the radiation distribution center of the laser light source 101 deviates from the axis of symmetry of the prism 102, it is difficult for the light intensity in the 0° direction to become 0. Here, the larger the expansion angle of the radiation distribution of the laser light source 101, the larger the allowable value of the deviation between the radiation distribution center of the laser light source 101 and the axis of symmetry of the prism 102.

[0083] According to such a structure, the light emitted from the laser light source 101 is split into two by the prism 102, diffused by the two refracting diffusion plates 106 and the diffusion plate 111, and the diffused light is overlapped. Thus, the light loss in the diffusion plate 106 and the diffusion plate 111 is small, and light with an expansion angle of 180° or more can be emitted.

[0084] In addition, by splitting the light source image of the laser light source 101 into two, the apparent light source emission size can be increased, and the laser output reaching laser class 1 can be improved. Therefore, a laser projection device capable of providing bright illumination can be provided.

[0085] 《Other Embodiments》

[0086] In the above-described embodiment, the following structure may also be adopted.

[0087] In this embodiment, the laser light source 101 uses a laser light source in which a plurality of laser light emitting elements are arranged to reduce spatial interference, but a laser light source with low spatial interference such as a multimode type semiconductor laser can also be used. In addition, a light emitting diode or a light emitting diode with a small emission diameter (SLD) can also be used.

[0088] In addition, if the speckle noise increases, it doesn't matter, and a single-mode type semiconductor laser can also be used. Moreover, if the device can be made larger, a HeNe, argon gas laser, etc. can also be used.

[0089] In addition, in this embodiment, the wavelength of the laser light source 101 is near infrared, but visible light can also be used when it doesn't matter that the measurement light is visible. Or, ultraviolet light can also be used. Additionally, setting the light source as the laser light source 101 results in poor response characteristics, but an LED can also be used.

[0090] In addition, in this embodiment, an antireflection film can also be formed on the planar portions 107 of the diffusion plate 106 and the diffusion plate 111 to reduce surface reflection.

[0091] In addition, in this embodiment, the diffusion plate 106 and the diffusion plate 111 can have the same divergence angle, or the shapes of the concave portion 109 and the convex portion 110 of the groove portion 108 can be changed to have different divergence angles.

[0092] In addition, in this embodiment, the cross-sectional shape of the prism 102 can be an isosceles triangle or a scalene triangle.

[0093] In addition, in this embodiment, the cross-section of the transparent housing 112 is set to a triangular shape, but it is not limited to this method. For example, due to the lens effect, the radiation angle distribution changes slightly, but it can also be a cylindrical shape that becomes a semicircle in the Figure 1 XY plane.

[0094] In addition, in this embodiment, in order to expand the light in the XZ plane direction, a diffusion plate that diffuses the light in the XZ plane can also be directly arranged after the laser light source 101.

[0095] The projection device according to the first aspect includes: a triangular prism having a first surface, a second surface, and a third surface; a light source that emits light to the first surface of the prism; and two diffusion plates that are respectively disposed opposite to the second surface and the third surface of the prism, and the apex angle formed by the second surface and the third surface of the prism is 5° or more and 90° or less.

[0096] The projection device according to the second mode may also be that, in the first mode, the diffusion surface of the diffusion plate is provided on the side facing the prism, and the surface on the opposite side of the diffusion surface of the diffusion plate is formed in a planar shape.

[0097] The projection device according to the third mode may also be that, in the second mode, the diffusion surface of the diffusion plate is formed in a groove shape in which a plurality of concave portions and convex portions are arranged adjacent to each other.

[0098] The projection device according to the fourth mode may also be that, in the third mode, the prism is formed in an extrusion shape with a fixed cross-sectional shape, and the groove portion of the diffusion surface of the diffusion plate extends substantially parallel to the extrusion direction of the prism.

[0099] The projection device according to the fifth mode may also be that, in the third or fourth mode, the light diffusion angle in the direction substantially parallel to the groove direction of the diffusion plate is smaller than the light diffusion angle in the direction substantially perpendicular to the groove direction of the diffusion plate.

[0100] The projection device according to the sixth mode may also be that, in any one of the first to fifth modes, the two diffusion plates are arranged with a predetermined gap therebetween.

[0101] The projection device according to the seventh mode may also be that, in any one of the first to sixth modes, the light expansion angles of the two diffusion plates are each 90° or more.

[0102] The projection device according to the eighth mode, in any one of the first to seventh modes, includes a transparent cover disposed outside the light source, the prism, and the two diffusion plates, and the transparent cover may have a surface substantially parallel to the diffusion plate for the incident light emitted from the diffusion plate and facing the diffusion plate.

[0103] The projection device according to the ninth mode, in any one of the first to eighth modes, the light source may also be a laser light source.

[0104] According to the present invention, the light loss in the diffusion plate is small, and light with a uniform and large emission angle can be emitted.

[0105] Industrial applicability

[0106] In the projection device of the present invention, the light loss in the diffusion plate is small and light with a large emission angle can be emitted, the apparent light beams in the emission surface of the projection device can be separated, and the output of the laser light source can be increased within the range of laser class 1. Therefore, it can also be applied to light sources for distance sensors of outdoor vehicle-mounted sensors, anti-theft sensors, indoor air conditioners, lighting, and other household appliances.

Claims

1. A projection device, characterized in that, it includes: A triangular prism having a first surface, a second surface, and a third surface; A light source that emits light to the first surface of the prism; and Two flat diffuser plates that are respectively disposed opposite to the second surface and the third surface of the prism, The apex angle formed by the second surface and the third surface of the prism is 5° or more and 90° or less, The light that is totally reflected on the second surface is incident on the third surface, and the light that is totally reflected on the third surface is incident on the second surface, whereby the light from the light source is divided into two, The light is incident on the two diffuser plates and diffused and transmitted in such a way that the light quantity center lines of the two divided lights deviate from the surface normals of the two diffuser plates respectively opposed to the second surface and the third surface by a specified angle, and the two diffused lights are overlapped. The light quantity center line represents the direction in which the light quantity of the radiation distribution is the largest.

2. The projection device according to claim 1, wherein, The diffusing surface of the diffuser plate is provided on the side opposite to the prism, The surface on the opposite side of the diffusing surface of the diffuser plate is formed in a planar shape.

3. The projection device according to claim 2, wherein, The diffusing surface of the diffuser plate is formed in a groove shape in which a plurality of concave portions and convex portions are arranged adjacent to each other.

4. The projection device according to claim 3, wherein, The prism is formed in an extrusion shape with a fixed cross-sectional shape, The groove portion of the diffusing surface of the diffuser plate extends substantially parallel to the extrusion direction of the prism.

5. The projection device according to claim 3 or 4, wherein, The light diffusion angle in the direction substantially parallel to the groove direction of the diffuser plate is smaller than the light diffusion angle in the direction substantially perpendicular to the groove direction of the diffuser plate.

6. The projection device according to any one of claims 1 to 4, wherein, The two diffuser plates are arranged with a specified gap therebetween.

7. The projection device according to any one of claims 1 to 4, wherein, The light expansion angles of the two diffuser plates are each 90° or more.

8. The projection device according to any one of claims 1 to 4, wherein, The projection device includes a transparent cover disposed outside the light source, the prism, and the two diffuser plates, The transparent cover has a surface that is substantially parallel to the diffuser plate and on which the light emitted from the diffuser plate is incident.

9. The projection device according to any one of claims 1 to 4, wherein, The light source is a laser light source.

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