Prism block and projection type image display device

Abstract

To provide a prism block capable of reducing stray light to an imaging element.SOLUTION: A prism block includes: a first prism that has a first surface, a second surface inclined with respect to the first surface, and a third surface connecting the first surface and the second surface; a second prism that is arranged on a side of the second surface of the first prism, and has a fourth surface parallel to the first surface, a fifth surface that is located on the side of the second surface with respect to the fourth surface, and is inclined in a direction different from an inclined direction of the second surface with respect to the first surface, and a sixth surface connecting the fourth surface and the fifth surface; a third prism that has a seventh surface facing the second surface via a gap and an eighth surface facing the fifth surface, and is arranged between the first prism and the second prism; and an optical path separation film that is arranged between the fifth surface of the second prism and the eighth surface of the third prism. A projection axis plane including optical paths of illumination light and projection light, and an imaging axis plane including an optical path of imaging light intersect each other.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a prism block and a projection-type image display device. [Background technology]

[0002] There is known a projection type image display device that projects an image onto a projection target such as a screen or a building. In a conventional projection type image display device, in order to check the positional relationship (distortion) between the projection target and the projected image, it has been considered to photograph the image projected onto the projection target and adjust the projection position based on the photographed image.

[0003] Therefore, a projection type image display device with a built-in imaging element has been considered. For example, Patent Document 1 discloses a projector equipped with a TIP prism that reflects light from a light source and guides it to a light modulation element, and transmits the light reflected by the light modulation element and outputs it to a projection optical system. In the projector described in Patent Document 1, the light incident on the TIR prism from the projection optical system is imaged by an imaging element arranged in the reflection direction of the TIR prism. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-218262 A Summary of the Invention [Problem to be solved by the invention]

[0005] The projector described in Patent Document 1 still has room for improvement in terms of reducing stray light to the imaging element.

[0006] The present disclosure provides a prism block and a projection-type image display device that can reduce stray light to an imaging element. [Means for solving the problem]

[0007] A prism block according to the present disclosure includes a first prism having a first surface, a second surface inclined with respect to the first surface, and a third surface connecting the first surface and the second surface and receiving incident illumination light; a second prism arranged on the second surface side of the first prism and having a fourth surface parallel to the first surface, a fifth surface located closer to the second surface side than the fourth surface and inclined with respect to the first surface in a direction different from that of the second surface, and a sixth surface connecting the fourth surface and the fifth surface; a third prism arranged between the first and second prisms and having a seventh surface facing the second surface via a gap and an eighth surface facing the fifth surface; and and an optical path separation film arranged between the fifth surface and the eighth surface of the third prism, wherein illumination light enters the first prism from the third surface and exits from the second surface, projection light enters the first prism from the first surface and passes through the third prism to exit from the fourth surface of the second prism, and imaging light enters the second prism from the fourth surface, is reflected by the optical path separation film, and exits from the sixth surface, and a projection axial plane including the optical paths of the illumination light and projection light from entering the first prism to exiting the second prism intersects with an imaging axial plane including the optical path of the imaging light from entering the fourth surface of the second prism to exiting from the sixth surface.

[0008] The projection type image display device according to the present disclosure comprises the above-mentioned prism block, a light source arranged on the third surface side of the first prism and irradiating illumination light, an image forming element arranged on the first surface side of the first prism and generating an image, a projection lens unit arranged on the fourth surface side of the second prism, and an imaging element arranged on the sixth surface side of the second prism and capturing imaging light. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a prism block and a projection-type image display device that can reduce stray light to an imaging element. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing a configuration of a projection type image display device according to a first embodiment; [Diagram 2]FIG. 2 is a view of the prism block included in the projection type image display device of FIG. 1 from a different angle. [Diagram 3] FIG. 1 is a perspective view showing a prism block according to a first embodiment; [Figure 4] FIG. 4 is an exploded perspective view of the prism block of FIG. [Diagram 5] FIG. 4 is a cross-sectional view showing the projection axis plane of the prism block of FIG. [Figure 6] FIG. 4 is a cross-sectional view showing the imaging axis plane of the prism block of FIG. [Figure 7] FIG. 13 is a perspective view showing a prism block according to the second embodiment; [Figure 8] FIG. 8 is a cross-sectional view showing the projection axis plane of the prism block of FIG. [Figure 9] FIG. 8 is a cross-sectional view showing the imaging axis plane of the prism block of FIG. [Figure 10] FIG. 13 is a schematic diagram showing a projection type image display device according to a third embodiment. [Figure 11] FIG. 11 is a view of the prism block included in the projection type image display device of FIG. 10, seen from another direction. [Figure 12] FIG. 11 is a perspective view showing the prism block and the color separation / combining prism of FIG. 10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (Background to this disclosure) In a projection type image display device, the use of a projection lens is being considered not only for projecting image light onto a projection target, but also for capturing an image of light from a projection target such as a screen. For example, in the projector described in Patent Document 1, a TIR prism that separates illumination light and projection light is also used to separate projection light and imaging light.

[0012] However, in the projector described in Patent Document 1, since the optical path of the video light and the optical path of the imaging light are shared, there is a problem that stray light in the optical path branching element enters the imaging element. If stray light enters the imaging element, it may affect the captured image.

[0013] Therefore, the present inventor(s) have investigated a projection type image display device that prevents stray light in an optical path branching element from entering an imaging element, and have arrived at the following invention.

[0014] Hereinafter, the embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters and duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

[0015] It should be noted that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0016] (Embodiment 1) [1-1. Configuration of projection type image display device] A projection-type image display device 300 according to the first embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a diagram showing the configuration of the projection-type image display device 300 according to the first embodiment. Fig. 2 is a diagram showing the prism block 1 included in the projection-type image display device 300 of Fig. 1 as viewed from another direction.

[0017] 1 and 2, the projection type image display device 300 is a device that includes a prism block 1, a light source 100, an image forming element 50, a projection lens unit 60, and an imaging element 70, and projects an image onto a screen 200 and captures the image projected onto the screen (projection target) 200. In the projection type image display device 300, light from the light source 100 enters the prism block 1, is reflected by the image forming element 50, passes through the prism block 1, exits from the projection lens unit 60, and is projected onto the screen 200.

[0018] In the light source 100, light is emitted from a semiconductor laser 201. The semiconductor laser 201 emits, for example, blue light with a wavelength centered at 456 nm. The polarization state of the light emitted from the semiconductor laser 201 is aligned so as to be S-polarized light.

[0019] Blue light emitted from semiconductor laser 201 passes through convex lens 202 and concave lens 203, and then through diffuser plate 204. Convex lens 202 and concave lens 203 are afocal lenses that re-parallelize the light emitted from semiconductor laser 201. The light that passed through diffuser plate 204 passes through convex lens 202 and concave lens 203 to be shaped into parallel light with a desired beam width, and then passes through diffuser plate 204 to reach dichroic mirror 209.

[0020] Dichroic mirror 209 has the property of reflecting S-polarized blue light. Therefore, the S-polarized blue light emitted from semiconductor laser 201 is reflected by dichroic mirror 209 and passes through ¼ wavelength plate 205. The light that passes through ¼ wavelength plate 205 is converted into circularly polarized light, passes through condenser lenses 206 and 207, and gradually converges to form an approximate image on phosphor wheel 208.

[0021] The phosphor wheel 208 is configured, for example, by providing a phosphor layer with a notch formed on the surface of a circular aluminum substrate. A rotary motor is disposed in the center of the aluminum substrate, and can rotate the phosphor wheel 208. The phosphor layer is formed, for example, by coating a YAG phosphor that is excited by blue light and emits yellow light containing green and red wavelength components. The notch portion of the phosphor layer is configured to reflect blue light. Light approximately focused on the phosphor layer of the phosphor wheel 208 is reflected as yellow light, and light focused on the notch portion is reflected as blue light. As the phosphor wheel 208 rotates, yellow light and blue light are emitted from the phosphor wheel 208 in a time-division manner.

[0022] The light reflected by phosphor wheel 208 passes through condenser lenses 206 and 207. Because the blue light is circularly polarized, it is converted to P-polarized light by quarter-wave plate 205, while the yellow light is unpolarized and therefore passes through dichroic mirror 209 in the same state even after passing through the quarter-wave plate, passing through condenser lens 210 and then through color wheel 211.

[0023] The color wheel 211 is, for example, a disk-shaped glass plate on the surface of which a plurality of color filters are formed in segments. The color filters are, for example, a dielectric multilayer film, and are divided into transparent, red, and green segments.

[0024] Of the light incident on color wheel 211, yellow light passes through all segments of the color filter, and blue light passes only through the transparent segments. Of the yellow light from phosphor wheel 208, light that passes through the transparent segments of the color filter is emitted from color wheel 211 as yellow light, light that passes through the red segments is emitted as red light, and light that passes through the green segments is emitted as green light. Blue light from phosphor wheel 208 passes through the transparent segments of the color filter and is emitted from color wheel 211 as blue light.

[0025] A rotary motor is disposed in the center of the disk-shaped glass plate, and is capable of rotating the color wheel 211. As the color wheel 211 rotates, blue, yellow, red, and green light are emitted from the color wheel 211 in a time-division manner.

[0026] The light transmitted through color wheel 211 enters rod integrator 212, passes through relay optical systems 213, 214, and 215, and enters prism block 1 as illumination light Ln1. Details of prism block 1 will be described later.

[0027] The illumination light Ln1 incident on the prism block 1 reaches the image forming element 50. In this embodiment, the image forming element 50 includes a single DMD (Digital Micromirror Device). Hereinafter, the image forming element 50 will be referred to as the DMD 50.

[0028] In the projection type image display device 300, the DMD 50 is modulated based on a control signal such as a video signal to generate projection light Pn1 with different light intensities. The DMD 50 has multiple movable micro mirrors. Each micro mirror corresponds to one pixel of an image. The DMD 50 changes the angle of the micro mirror based on the control signal to separate the projection light Pn1 (DMD-ON light) toward the projection lens unit 60 and illumination light Ln2 (DMD-OFF light) that does not enter the projection lens unit 60.

[0029] The projection light Pn1 (DMD-ON light) that is projected as an image is reflected by the DMD 50, enters the prism block 1 again, enters the projection lens unit 60, and is then projected onto the screen 200. The illumination light Ln2 (DMD-OFF light) that is not projected as an image does not enter the projection lens unit 60, but passes through the prism block 1.

[0030] The projection lens unit 60 includes a plurality of lenses, and magnifies the projection light Pn1 emitted from the prism block 1 and projects it onto the screen 200. Illumination light Ln1 from the light source 100 is reflected by the DMD 50 as DMD-ON light (projection light Pn1), reaches the screen 200 via the projection lens unit 60, and is perceived as a full-color image Im1. Note that the image includes both still images and moving images.

[0031] The imaging light Sn1, which includes the projection light Pn1 reflected by the screen 200, enters the prism block 1, and is reflected inside the prism block 1 and received by the imaging element 70, as shown in FIG.

[0032] [1-2. Prism block configuration] Fig. 3 is a perspective view showing the prism block 1 according to the first embodiment. Fig. 4 is an exploded perspective view of the prism block 1 of Fig. 3.

[0033] 3 and 4, the prism block 1 includes a first prism 10, a second prism 20, a third prism 30, and an optical path separation film 40. The prism block 1 serves to totally internally reflect illumination light Ln1 from a light source 100 and emit the light to a DMD 50, and to separate the optical path of projection light Pn1 from the DMD 50 and the optical path of imaging light Sn1 from a screen 200.

[0034] The first prism 10 has a first surface 11, a second surface 12 inclined with respect to the first surface 11, and a third surface 13 that connects the first surface 11 and the second surface 12 and on which the illumination light Ln1 is incident. In this embodiment, the first prism 10 is a prism having a triangular pole shape. The first surface 11 is disposed perpendicular to the optical axis of the projection light Pn1 from the DMD 50.

[0035] The second prism 20 is disposed on the second surface 12 side of the first prism 10 and has a fourth surface 21 parallel to the first surface 11, a fifth surface 22 located closer to the second surface 12 than the fourth surface and inclined in a different direction from the second surface 12 with respect to the first surface 11, and a sixth surface 23 connecting the fourth surface 21 and the fifth surface 22. In this embodiment, the second prism 20 is a prism having a triangular pole shape.

[0036] The third prism 30 is disposed between the first prism 10 and the second prism 20. The third prism 30 has a seventh surface 31 facing the second surface 12 via a gap Sp, and an eighth surface 32 facing the fifth surface 22. The gap Sp between the second surface 12 and the seventh surface 31 is formed to have a size of, for example, 3 μm or more and 10 μm or less.

[0037] We will now explain the arrangement of the first surface 11 and the second surface 12 of the first prism 10, the arrangement of the fourth surface 21 and the fifth surface 22 of the second prism 20, and the arrangement of the seventh surface 31 and the eighth surface 32 of the third prism 30, when the three mutually perpendicular directions are the X direction, the Y direction, and the Z direction.

[0038] The first surface 11 of the first prism 10 is located on an XY plane extending in the +X and +Y directions. The second surface 12 is inclined in the +Z direction with respect to the first surface 11 and is located on an inclined plane extending between the +X and +Z directions. The second surface 12 is inclined at an inclination angle θ1 with respect to the first surface 11. The inclination angle θ1 is the angle between the first surface 11 and the second surface 12, and is preferably 28 degrees or more and 35 degrees or less. The third surface 13 is preferably disposed so that the incident angle of the illumination light Ln1 is vertical.

[0039] The fourth surface 21 of the second prism is located in the +Z direction from the first surface 11 of the first prism 10, and is located on a plane parallel to the first surface 11. The fifth surface 22 is inclined in the -Z direction from the fourth surface 21, and is located on an inclined plane extending between the -Y direction and the -Z direction. The fifth surface 22 is inclined at an inclination angle θ2 with respect to the fourth surface 21. The inclination angle θ2 is the angle between the fourth surface 21 and the fifth surface 22, and is preferably 25 degrees or more and 32 degrees or less.

[0040] Since the first surface 11 of the first prism 10 and the fourth surface 21 of the second prism 20 are arranged parallel to each other, the fifth surface 22 of the second prism 20 is also inclined with respect to the first surface 11 of the first prism 10. The fifth surface 22 of the second prism 20 is inclined with respect to the first surface 11 in a direction different from that of the second surface 12.

[0041] The seventh surface 31 of the third prism 30 is located in the +Z direction from the second surface 12 of the first prism 10. A gap Sp is formed between the second surface 12 and the seventh surface 31. The seventh surface 31 is located on an inclined plane facing the second surface 12, i.e., an inclined plane extending between the +X direction and the +Z direction. The eighth surface 32 of the third prism 30 is located in the -Z direction from the fifth surface 22 of the second prism 20. The fifth surface 22 and the eighth surface 32 are bonded together via the optical path separation film 40. The eighth surface 32 is located on an inclined plane facing the fifth surface 22, i.e., an inclined plane extending between the -Y direction and the -Z direction.

[0042] The optical path separation film 40 is disposed between the fifth surface 22 of the second prism 20 and the eighth surface 32 of the third prism 30. The optical path separation film 40 is composed of, for example, a partial reflection mirror such as a half mirror that reflects a part of the light incident on the prism block 1 and transmits the remaining part.

[0043] Fig. 5 is a cross-sectional view showing the projection axial plane PA1 of the prism block 1 of Fig. 3. With reference to Fig. 5, the optical paths of the illumination light Ln1 and the projection light Pn1 within the prism block 1 will be described.

[0044] Illumination light Ln1 from the light source 100 enters the third surface 13 of the first prism 10, is reflected by the second surface 12, exits from the first surface 11, and reaches the DMD 50. Projection light Pn1 (DMD-ON light) reflected by the DMD 50 enters the first prism 10 from the first surface 11 and exits from the second prism 20 via the third prism 30. More specifically, illumination light Ln1 from the light source 100 enters the first prism 10 from the third surface 13, is reflected by the second surface 12, exits from the first surface 11, is reflected by the image forming element (DMD) 50, and enters the first prism 10 again as projection light Pn1. Since a gap Sp is formed between the second surface 12 of the first prism 10 and the seventh surface 31 of the third prism 30 facing the second surface 12, the illumination light Ln1 is totally internally reflected at the second surface 12 of the first prism 10. Total internal reflection means that the illumination light Ln1 incident on the first prism 10 is totally reflected at the second surface 12 without being transmitted to the outside from the second surface 12 of the first prism 10.

[0045] The projection light Pn1 (DMD-ON light) reflected by the DMD 50 enters the first prism 10 again from the first surface 11, passes through the third prism 30, exits from the fourth surface 21 of the second prism 20, and is projected onto the screen 200 via the projection lens unit 60. The illumination light Ln2 (DMD-OFF light) reflected by the DMD 50 and not projected as an image does not enter the projection lens unit 60, but is output from the prism block 1 to the outside.

[0046] 5, the optical paths of the illumination light Ln1, the projection light Pn1 (DMD-ON light), and the illumination light Ln2 (DMD-OFF light) are included in the projection axial plane PA1. The optical path of the illumination light Ln1 is the path of light from the light source 100 entering the first prism 10 from the third surface 13 until it reaches the DMD 50. The optical path of the projection light Pn1 is the path of light reflected by the DMD 50, entering the first prism 10, passing through the third prism 30, and exiting from the fourth surface 21 of the second prism 20. The optical path of the illumination light Ln2 (DMD-OFF light) reflected by the DMD 50 is also included in the projection axial plane PA1.

[0047] Fig. 6 is a cross-sectional view showing an imaging axial plane IA1 of the prism block 1 of Fig. 3. With reference to Fig. 6, the optical path of the imaging light Sn1 within the prism block 1 will be described.

[0048] The imaging light Sn1 is light including the projection light Pn1 reflected by the screen 200. The imaging light Sn1 enters the second prism 20 from the fourth surface 21 via the projection lens unit 60, is reflected by the optical path separation film 40, and is further totally internally reflected by the fourth surface 21 to exit from the sixth surface 23 and is received by the imaging element 70 arranged on the sixth surface 23 side.

[0049] 6, the optical path of the imaging light Sn1 is included in the imaging axial plane IA1. The optical path of the imaging light Sn1 is the path of the imaging light Sn1 reflected by the screen 200 from the fourth surface 21 of the second prism 20 to the sixth surface 23.

[0050] As shown in Fig. 3, the projection axial plane PA1 and the imaging axial plane IA1 intersect. By intersecting the projection axial plane PA1 and the imaging axial plane IA1, stray light due to the projection light Pn1 (DMD-ON light) and the illumination light Ln2 (DMD-OFF light) is less likely to enter the imaging axial plane IA1. Therefore, the stray light incident on the imaging element 70 can be reduced.

[0051] The greater the intersection angle between the projection axial plane PA1 and the imaging axial plane IA1, i.e., the intersection angle θ3 (see FIG. 3) between the projection axial plane PA1 and the imaging axial plane IA1, the more the stray light entering the imaging element 70 is attenuated. The intersection angle θ3 is the angle between the projection axial plane PA1 and the imaging axial plane IA1 when viewed from the Z direction. For this reason, the intersection angle θ3 between the projection axial plane PA1 and the imaging axial plane IA1 is preferably 45 degrees or more and 135 degrees or less. More preferably, the projection axial plane PA1 and the imaging axial plane IA1 are orthogonal to each other. In this embodiment, the projection axial plane PA1 is located on the XZ plane, the imaging axial plane IA1 is located on the YZ plane, and the projection axial plane PA1 and the imaging axial plane IA1 are orthogonal to each other.

[0052] In this embodiment, the prism block 1 serves as a TIR prism (total internal reflection prism) that internally reflects the illumination light Ln1 and outputs it toward the DMD 50, and as an optical path separation prism that separates the optical path of the imaging light Sn1 from the optical path of the projection light Pn1. By configuring the TIR prism and the optical path separation prism in one prism block 1, it is possible to make the prism block 1 thinner. This contributes to the miniaturization of the projection type image display device 300.

[0053] [1-3. Effects, etc.] According to the embodiment described above, the projection axial plane PA1 and the imaging axial plane IA1 intersect. Therefore, it is possible to prevent the illumination light Ln2 (DMD-OFF light) that is not projected as an image reflected by the DMD 50 from being reflected inside the prism block 1 from entering the imaging element 70. Therefore, it is possible to reduce stray light to the imaging element 70.

[0054] In addition, the prism block 1 is configured by combining the TIR prism and the optical path separation prism into one prism block. Therefore, the prism block 1 can be made thinner than when the TIR prism and the optical path separation prism are provided separately. This contributes to making the projection type image display device 300 more compact.

[0055] By providing the optical path separation film 40 between the second prism 20 and the third prism 30, the optical path of the projection light Pn1 and the optical path of the imaging light Sn1 are separated. Therefore, it is possible to reduce attenuation of the illumination light Ln1 when it enters the DMD 50, and it is possible to increase the amount of the projection light Pn1 projected onto the screen 200.

[0056] The imaging light Sn1 incident on the prism block 1 is reflected by the optical path separation film 40, and is further totally internally reflected by the fourth surface 21 inside the second prism 20, and then enters the imaging element 70. Therefore, stray light incident on the imaging element 70 can be reduced.

[0057] In the above-described embodiment, the light path separation film 40 is a partially reflective mirror, but the present invention is not limited to this. The light path separation film 40 may be, for example, a polarization separation film. The polarization separation film is a film that transmits light in a first polarization state, either P polarization or S polarization, and reflects light in the other second polarization state, either P polarization or S polarization. In this case, the projection light Pn1 has a first polarization state or a second polarization state.

[0058] (Embodiment 2) A second embodiment will be described with reference to Figures 7 to 9. In the second embodiment, the same or equivalent configurations as those in the first embodiment will be denoted by the same reference numerals. In the second embodiment, descriptions that overlap with those in the first embodiment will be omitted.

[0059] Fig. 7 is a perspective view showing a prism block 1A according to the second embodiment. Fig. 8 is a cross-sectional view showing a projection axial plane PA2 of the prism block 1A of Fig. 7. Fig. 9 is a cross-sectional view showing an imaging axial plane IA2 of the prism block 1A of Fig. 7.

[0060] In the second embodiment, as shown in Fig. 7, the shape of the second prism 120 is different from that of the first embodiment, and accordingly, the shape of the third prism 130 is also different from that of the first embodiment. Specifically, the second prism 120 is formed so that the inclination angle θ4 between the fourth surface 121 and the fifth surface 122 is larger than that of the first embodiment. In the present embodiment, the inclination angle θ4 is 45 degrees. Therefore, after the imaging light Sn2 is reflected by the optical path separation film 40, it is received by the imaging element 70 without being totally internally reflected by the second prism 120.

[0061] 8, illumination light Ln3 from light source 100 is incident on the third surface 113 of first prism 110, is totally internally reflected on the second surface 112, and is emitted from the first surface 111 towards DMD 50. Furthermore, projection light Pn2 (DMD-ON light) reflected on DMD 50 is incident on first prism 110 again from the first surface 111, passes through third prism 130, exits second prism 120 from fourth surface 121, and is incident on projection lens unit 60.

[0062] Illumination light Ln4 (DMD-OFF light) that is reflected by the DMD 50 and is not projected as an image does not enter the projection lens unit 60 but is output to the outside from the prism block 1A.

[0063] 9, imaging light Sn2 is incident on the fourth surface 121 of the second prism 120, reflected by the optical path separation film 140, exits from the sixth surface 123, and is received by the imaging element 70. Unlike the first embodiment, the inclination angle θ4 between the fourth surface 121 and the fifth surface 122 is 45 degrees, so that after being incident on the second prism 120, the imaging light Sn2 exits from the sixth surface 123 after being reflected once by the optical path separation film 140.

[0064] According to the above-described embodiment, even if the optical path of the imaging light Sn2 inside the second prism 120 is different, the intrusion of stray light into the imaging element 70 can be reduced because the projection axial plane PA2 and the imaging axial plane IA2 intersect.

[0065] (Embodiment 3) A third embodiment will be described with reference to Fig. 10 to Fig. 12. In the third embodiment, the same or equivalent configurations as those in the first embodiment will be denoted by the same reference numerals. In the third embodiment, descriptions that overlap with those in the first embodiment will be omitted.

[0066] Fig. 10 is a schematic diagram showing a projection type image display device 300A according to the third embodiment. Fig. 11 is a diagram showing the prism block 1 included in the projection type image display device 300A of Fig. 10 from another direction. Fig. 12 is a perspective view showing the prism block 1 and a color separation / combining prism 54 of Fig. 10.

[0067] The third embodiment differs from the first embodiment in that the image forming element includes three DMDs (Digital Micromirror Devices) that modulate red, green, and blue light. As shown in Fig. 10, the image forming element includes a DMD 51 that modulates blue light, a DMD 52 that modulates green light, and a DMD 53 that modulates red light. Also, the third embodiment differs from the first embodiment in the configuration of the light source 100A.

[0068] As shown in Figs. 10 to 12, the projection type image display device 300A includes a prism block 1, a color separation / synthesis prism 54, a light source 100A, image forming elements 51, 52, and 53, a projection lens unit 60, and an image sensor 70. The projection type image display device 300A projects an image onto a screen 200 and captures an image of the image projected onto the screen 200. In the projection type image display device 300A, white illumination light Ln5 from the light source 100A is incident on a first prism 10 and then separated into red, green, and blue light by the color separation / synthesis prism 54. The red light is reflected by the DMD 53, the green light is reflected by the DMD 52, and the blue light is reflected by the DMD 51. The projection light Pn3 reflected by the DMDs 51 to 53 enters the first prism 10 of the prism block 1 again via the color separation / combining prism 54, and is emitted to the projection lens unit 60 from the fourth surface 21 of the second prism 20 via the third prism 30.

[0069] In the light source 100A, light is emitted from semiconductor lasers 201A and 201B. The semiconductor lasers 201A and 201B emit, for example, blue light with a wavelength centered at 456 nm. The polarization state of the light emitted from the semiconductor lasers 201A and 201B is aligned to be P-polarized light.

[0070] The blue light emitted from semiconductor laser 201A passes through convex lens 202A and concave lens 203A, and then through diffuser plate 204A. Convex lens 202A and concave lens 203A are afocal lenses that re-parallelize the light emitted from semiconductor laser 201A. The light that passed through diffuser plate 204A passes through convex lens 202A and concave lens 203A to be shaped into parallel light with a desired beam width, and then passes through diffuser plate 204A to reach dichroic mirror 209A.

[0071] Dichroic mirror 209A has the property of transmitting P-polarized blue light. Therefore, the P-polarized blue light emitted from semiconductor laser 201A is transmitted by dichroic mirror 209A, transmitted through condenser lenses 206 and 207, and gradually condensed to form an approximate image on phosphor wheel 208A.

[0072] The phosphor wheel 208A is configured, for example, by providing a phosphor layer on the surface of a circular aluminum substrate. A rotary motor is disposed in the center of the aluminum substrate, and can rotate the phosphor wheel 208A. The phosphor layer is formed, for example, by coating a YAG phosphor that is excited by blue light and emits yellow light containing green and red wavelength components. The light approximately focused on the phosphor layer of the phosphor wheel 208A is reflected as yellow light. As the phosphor wheel 208A rotates, yellow light is continuously emitted from the phosphor wheel 208A.

[0073] The yellow light reflected by phosphor wheel 208 A passes through condenser lenses 206 and 207 , is reflected by dichroic mirror 209 A, passes through condenser lens 210 , and enters rod integrator 212 .

[0074] On the other hand, the blue light emitted from semiconductor laser 201B passes through convex lens 202B and concave lens 203B, and then passes through diffuser plate 204B. Convex lens 202B and concave lens 203B are afocal lenses that re-parallelize the light emitted from semiconductor laser 201B. The blue light that passed through diffuser plate 204B passes through convex lens 202B and concave lens 203B to be shaped into parallel light with a desired beam width, passes through diffuser plate 204B, and is reflected by mirror 216 to reach dichroic mirror 209A.

[0075] P-polarized blue light emitted from semiconductor laser 201B passes through dichroic mirror 209A, is combined with yellow light reflected by dichroic mirror 209A, passes through condenser lens 210, and enters rod integrator 212.

[0076] The light incident on rod integrator 212 passes through relay optical systems 213, 214, and 215 and enters prism block 1 as illumination light Ln5.

[0077] As shown in FIG. 10, illumination light Ln6 (DMD-OFF light) that is not projected as an image does not enter the projection lens unit 60, but passes through the prism block 1.

[0078] In the present embodiment, the prism optical path length of the projection light Pn3 from the DMD 51, DMD 52, and DMD 53 to the projection lens unit 60 is longer than the optical path length of the projection light Pn1 (see FIG. 1) in the first embodiment. For this reason, as shown in FIG. 10, optical systems 71 and 72 are disposed between the second prism 20 and the imaging element 70 to adjust the optical path length of the imaging light Sn3 until it reaches the imaging element 70.

[0079] In this embodiment, similarly to the first embodiment, the projection axial plane PA3 and the imaging axial plane IA3 intersect (see FIG. 12).

[0080] The imaging light Sn3 is disposed closer to the projection lens unit 60 than the color separation / synthesis prism 54. Therefore, white light can be taken into the imaging element 70.

[0081] (Other embodiments) As described above, the above embodiment has been described as an example of the technology disclosed in this application. However, the technology in this disclosure is not limited to this, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made. In addition, it is also possible to combine the components described in the above embodiment to create a new embodiment.

[0082] In the above-described embodiment, the first prism 10 and the second prism 20 have a triangular prism shape, but the shape of the first prism 10 and the second prism 20 is not limited to a triangular prism shape.

[0083] As described above, the embodiment has been described as an example of the technology in the present disclosure. For this purpose, the attached drawings and detailed description have been provided. Therefore, among the components described in the attached drawings and detailed description, not only components essential for solving the problem but also components that are not essential for solving the problem in order to exemplify the above technology may be included. Therefore, the fact that these non-essential components are described in the attached drawings or detailed description should not be used to immediately determine that these non-essential components are essential.

[0084] Furthermore, since the above-described embodiments are intended to illustrate the technology in the present disclosure, various modifications, substitutions, additions, omissions, and the like can be made within the scope of the claims or their equivalents.

[0085] (Outline of the embodiment) (1) A prism block of the present disclosure includes a first prism having a first surface, a second surface inclined with respect to the first surface, and a third surface connecting the first surface and the second surface and receiving incident illumination light; a second prism arranged on the second surface side of the first prism and having a fourth surface parallel to the first surface, a fifth surface located closer to the second surface side than the fourth surface and inclined with respect to the first surface in a direction different from that of the second surface, and a sixth surface connecting the fourth surface and the fifth surface; a third prism arranged between the first prism and the second prism, having a seventh surface facing the second surface via a gap and an eighth surface facing the fifth surface; and and an optical path separation film arranged between the fifth surface and the eighth surface of the third prism, wherein illumination light enters the first prism from the third surface and exits from the second surface, projection light enters the first prism from the first surface and passes through the third prism to exit from the fourth surface of the second prism, and imaging light enters the second prism from the fourth surface, is reflected by the optical path separation film, and exits from the sixth surface, and a projection axial plane including the optical paths of the illumination light and projection light from entering the first prism to exiting the second prism intersects with an imaging axial plane including the optical path of the imaging light from entering the fourth surface of the second prism to exiting from the sixth surface.

[0086] With this configuration, the optical path of the illumination light and the optical path of the imaging light can be separated, so that stray light to the imaging element can be reduced.

[0087] (2) In the prism block (1), the projection axis plane and the imaging axis plane are perpendicular to each other.

[0088] With this configuration, the effect of attenuating stray light can be improved.

[0089] (3) In the prism block of (1) or (2), the illumination light enters the first prism from the third surface, is reflected by the second surface, exits from the first surface, and reaches the image forming element that generates an image, the projection light is reflected by the image forming element, enters the first prism from the first surface, passes through the third prism, exits from the fourth surface of the second prism, and is projected onto the projection target (screen) via the projection lens unit, and the imaging light includes the projection light reflected from the projection target, enters the second prism from the fourth surface via the projection lens unit, is reflected by the optical path separation film, exits from the sixth surface, and is received by the imaging element located on the sixth surface side.

[0090] With this configuration, the optical paths of the illumination light and projection light and the optical path of the imaging light can be separated, thereby increasing the amount of illumination light projected onto the projection target without attenuating the illumination light with the optical path separation film.

[0091] (4) In any one of the prism blocks (1) to (3), when the three mutually perpendicular directions are the X direction, the Y direction, and the Z direction, the first surface is located on an XY plane extending in the +X direction and the +Y direction, the second surface is inclined in the +Z direction relative to the first surface and is located on an inclined plane extending between the +X direction and the +Z direction, the fourth surface is located in the +Z direction from the first surface and is located on a plane parallel to the first surface, and the fifth surface is inclined in the -Z direction from the fourth surface and is located on an inclined plane extending between the -Y direction and the -Z direction.

[0092] With this configuration, the optical path of the illumination light and the optical path of the imaging light can be separated, so that stray light to the imaging element can be reduced.

[0093] (5) In any one of the prism blocks (1) to (4), the gap between the second surface and the seventh surface is set to be equal to or greater than 3 μm and equal to or less than 10 μm.

[0094] With this configuration, the probability that illumination light incident on the first prism from the third surface will be totally reflected by the second surface increases, making it possible to reduce stray light incident on the imaging element.

[0095] (6) In any one of the prism blocks (1) to (5), the optical path separation film transmits light of a first polarization state, either P polarization or S polarization, and reflects light of a second polarization state, either P polarization or S polarization, the other.

[0096] With this configuration, the polarization states of the illumination light and the imaging light can be changed, so that stray light entering the imaging element can be reduced.

[0097] (7) In any one of the prism blocks (1) to (5), the light path separation film is a partial reflection mirror that reflects a part of the light.

[0098] With this configuration, the projection light can be transmitted through the light path separation film without attenuating the illumination light, and the imaging light can be reflected by the light path separation film, so that the optical paths of the illumination light and the imaging light can be separated.

[0099] (8) The projection type image display device of the present disclosure comprises a prism block selected from any one of (1) to (7), a light source arranged on the third surface side of the first prism and irradiating illumination light, an image forming element arranged on the first surface side of the first prism and generating an image, a projection lens unit arranged on the fourth surface side of the second prism, and an imaging element arranged on the sixth surface side of the second prism and capturing imaging light.

[0100] With this configuration, the functions of a TIR prism and an optical path separation prism can be realized in a single prism block, which contributes to the miniaturization of projection-type image display devices.

[0101] (9) In the projection type image display device of (8), the image forming element includes a single DMD (Digital Micromirror Device).

[0102] With this configuration, it is possible to provide a small projection type image display device that prevents stray light from entering the imaging element.

[0103] (10) In the projection type image display device of (8), the image forming element includes three DMDs (Digital Micromirror Devices) that modulate red, green, and blue light.

[0104] With this configuration, it is possible to provide a small projection type image display device that prevents stray light from entering the imaging element. [Industrial Applicability]

[0105] The present disclosure can be used in a projection-type image display device that projects an image. [Explanation of symbols]

[0106] 1, 1A Prism block 10, 110 First prism 11, 111 1st page 12, 112 2nd page 13, 113 3rd page 20, 120 Second prism 21, 121 4th page 22, 122 Page 5 23, 123 Page 6 30, 130 Third Prism 31 Page 7 32 Page 8 40, 140 Optical path separation membrane 50 Image forming element 60 Projection lens unit 70 Image sensor 100 light sources 200 screens (projection targets) 300, 300A Projection type image display device IA1, IA2, IA3 Imaging axial plane Ln1, Ln3, Ln5 Illumination Ln2, Ln4, Ln6 Illumination light (DMD-OFF light) Pn1, Pn2, Pn3 (projection light) Sn1, Sn2, Sn3 Imaging light PA1, PA2, PA3 Projection axis plane Sp void

Claims

1. a first prism having a first surface, a second surface that intersects with the first surface at a first intersection line and is inclined with respect to the first surface, and a third surface that connects the first surface and the second surface and on which illumination light is incident; a second prism having a fourth surface disposed on the second surface side of the first prism and parallel to the first surface, a fifth surface located closer to the second surface than the fourth surface, intersecting with the first surface at a second intersection line that intersects with the first intersection line and inclined with respect to the first surface, and a sixth surface connecting the fourth surface and the fifth surface; a third prism having a seventh surface facing the second surface with a gap therebetween and an eighth surface facing the fifth surface, the third prism being disposed between the first prism and the second prism; an optical path separation film disposed between the fifth surface of the second prism and the eighth surface of the third prism; Equipped with the illumination light is incident on the first prism from the third surface and exits from the first surface, the projection light is incident on the first prism from the first surface, passes through the third prism, and exits from the fourth surface of the second prism; imaging light is incident on the second prism from the fourth surface, reflected by the optical path separation film, and exits from the sixth surface; a projection axial plane including optical paths of the illumination light and the projection light from entering the first prism to exiting the second prism and an imaging axial plane including an optical path of the imaging light from entering the fourth surface of the second prism to exiting the sixth surface intersect with each other; Prism block.

2. A first prism having a first surface, a second surface inclined relative to the first surface, and a third surface connecting the first surface and the second surface and onto which illumination light is incident; a second prism having a fourth surface disposed on the second surface side of the first prism and parallel to the first surface, a fifth surface located closer to the second surface than the fourth surface and inclined relative to the first surface in a direction different from that of the second surface, and a sixth surface connecting the fourth surface and the fifth surface; a third prism having a seventh surface facing the second surface with a gap therebetween and an eighth surface facing the fifth surface, the third prism being disposed between the first prism and the second prism; an optical path separation film disposed between the fifth surface of the second prism and the eighth surface of the third prism; Equipped with When the three mutually orthogonal directions are defined as the X direction, the Y direction, and the Z direction, the first surface is located in an XY plane extending in a +X direction and a +Y direction; the second surface is inclined in the +Z direction with respect to the first surface and is located on an inclined plane extending between the +X direction and the +Z direction; the fourth surface is located in a +Z direction from the first surface and is located on a plane parallel to the first surface, the fifth surface is inclined in the −Z direction from the fourth surface and is located on an inclined plane extending between the −Y direction and the −Z direction; the illumination light is incident on the first prism from the third surface and exits from the first surface, the projection light is incident on the first prism from the first surface, passes through the third prism, and exits from the fourth surface of the second prism; imaging light is incident on the second prism from the fourth surface, reflected by the optical path separation film, and exits from the sixth surface; a projection axial plane including optical paths of the illumination light and the projection light from entering the first prism to exiting the second prism and an imaging axial plane including an optical path of the imaging light from entering the fourth surface of the second prism to exiting the sixth surface intersect with each other; Prism block.

3. The projection axis plane and the imaging axis plane are perpendicular to each other. The prism block according to claim 1 or 2.

4. the illumination light is incident on the first prism from the third surface, reflected by the second surface, and exits from the first surface to reach an image forming element that generates an image; the projection light is reflected by the image forming element, enters the first prism from the first surface, passes through the third prism, exits from the fourth surface of the second prism, and is projected onto a projection target via a projection lens unit; the imaging light includes the projection light reflected by the projection target, is incident on the second prism from the fourth surface via the projection lens unit, is reflected by the optical path separation film, is emitted from the sixth surface, and is received by an imaging element disposed on the sixth surface side. The prism block according to claim 1 .

5. The gap between the second surface and the seventh surface is provided to have a size of 3 μm or more and 10 μm or less. The prism block according to claim 1 .

6. the optical path separation film transmits light in a first polarization state, which is either P polarized light or S polarized light, and reflects light in the other second polarization state, which is either P polarized light or S polarized light; The prism block according to claim 1 .

7. The optical path separation film is a partial reflection mirror that reflects a part of the light. The prism block according to claim 1 .

8. A prism block according to any one of claims 1 to 7, a light source disposed on the third surface side of the first prism and configured to emit the illumination light; an image forming element disposed on the first surface side of the first prism and generating an image; a projection lens unit disposed on the fourth surface side of the second prism; an imaging element disposed on the sixth surface side of the second prism and configured to capture the imaging light; Equipped with Projection type image display device.

9. The image forming element includes a single DMD (Digital Micromirror Device), 9. The projection type image display device according to claim 8.

10. The image forming element includes three DMDs (Digital Micromirror Devices) that modulate red, green, and blue light; 9. The projection type image display device according to claim 8.

Images