Projector

Abstract

To suppress a thermal load applied to an optical element and a component arranged at a stage subsequent to a light guide element in a projector.SOLUTION: A projector includes: a first light source that emits first light in a first wavelength band; a first light guide element having a first incident end on which the first light emitted from the first light source is incident and a first emission end from which the first light is emitted; a first light modulation element that modulates a first polarization component of the first light emitted from the first light guide element on the basis of image information; and a projection optical system that projects the light emitted from the first light modulation element. The first light guide element has a first base material and a first reflective film which is arranged on a first surface forming an inner surface of the first light guide element in the first base material, the first reflective film reflects the first polarization component and transmits a second polarization component of the first light, and the first polarization component reflected by the first reflective film is emitted from the first emission end.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a projector. [Background technology]

[0002] Conventionally, there has been known a projector that includes a light source that emits colored light, a light modulation element that generates image light from the colored light emitted from the light source, and a projection optical system that projects the image light emitted from the light modulation element. There are various types of projectors, such as single-panel types and three-panel types, depending on the number of light sources and light modulation elements.

[0003] For example, Patent Document 1 discloses a projector that uses multiple light-emitting diodes (LEDs) as light-emitting elements of the light source. In the projector disclosed in Patent Document 1, colored light emitted from each LED passes through a block, is superimposed on a path in the same direction, is modulated into image light by a light modulation element, and is projected by a projection lens. The brightness of the colored light emitted from the exit end of each block is uniform within a plane intersecting the optical axis. The colored light emitted from the multiple blocks is incident on a dichroic prism that combines the light from the multiple LEDs. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Application No. 10-361256 Summary of the Invention [Problem to be solved by the invention]

[0005] In the three-plate projector disclosed in Patent Document 1, all polarized components of light emitted from the light source are reflected by the side wall surface of the block, which acts as a reflector, and all polarized components are guided to the exit end of the block and emitted toward the light modulation element. Since all polarized components of light emitted from the light source include polarized components that do not contribute to image formation, these polarized components of light that do not contribute to image formation are incident on optical elements and components downstream of the block, including the light modulation element. In the projector disclosed in Patent Document 1, there is a possibility that the thermal load on the optical elements and components located downstream of the block will be large. [Means for solving the problem]

[0006] The projector of this embodiment includes a first light source that emits first light of a first wavelength band, a first light guide element having a first incident end into which the first light emitted from the first light source is incident and a first exit end from which the first light is emitted, a first light modulation element that modulates a first polarization component of the first light emitted from the first light guide element based on image information, and a projection optical system that projects the light emitted from the first light modulation element. The first light guide element has a first base material and a first reflective film arranged on a first surface of the first base material that forms the inner surface of the first light guide element, the first reflective film reflecting the first polarization component and transmitting a second polarization component of the first light, and the first polarization component reflected by the first reflective film being emitted from the first exit end. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram illustrating a configuration of a projector according to an embodiment. [Figure 2] 2 is a perspective view of a light guide element of a blue light emitting section of the projector in FIG. 1. FIG. [Figure 3] 2 is a cross-sectional view of a light source, a light guide element, a collimating element, an incident-side polarizing element, and a light modulation element of a blue light emitting unit of the projector of FIG. 1. [Figure 4] 2 is a cross-sectional view of a light source, a light guide element, a collimating element, an incident-side polarizing element, and a light modulation element of a green light emitting unit of the projector of FIG. 1. [Figure 5]2 is a cross-sectional view of a light source, a light guide element, a collimating element, an incident-side polarizing element, and a light modulation element of a red light emitting unit of the projector of FIG. 1. [Figure 6] 1. FIG. 4 is a cross-sectional view of a light source and a light guide element of a blue light emitting unit of a second modified example of the projector of FIG. [Figure 7] 1. FIG. 9 is a cross-sectional view of a light source and a light guide element of a blue light emitting unit of a third modified example of the projector of FIG. [Figure 8] 1. FIG. 10 is a cross-sectional view of a light source and a light guide element of a blue light emitting unit of a fourth modified example of the projector of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each drawing, the scale of the dimensions of some components may be changed to make the components easier to see.

[0009] First, an embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG. 1 is a schematic diagram showing the configuration of a projector 301 according to an embodiment of the present invention. The projector 301 is an image display device equipped with three liquid crystal panels as light modulation devices, and is a so-called three-panel projector. As shown in FIG. 1, the projector 301 includes a blue light output unit 101, a green light output unit 102, a red light output unit 103, incident-side polarizing elements 171, 172, and 173, light modulation elements 181, 182, and 183, exit-side polarizing elements 175, 176, and 177, a light combining element 200, and a projection optical system 250.

[0010] The blue light output unit 101 outputs blue light LB. In the following description, the direction of an axis parallel to the optical axis of the blue light LB output from the blue light output unit 101 is referred to as the D1 direction. One side of the D1 direction is referred to as the -D1 side, and the side opposite the -D1 side of the D1 direction is referred to as the +D1 side. The direction perpendicular to the D1 direction in a plane including the optical axis of the blue light LB is referred to as the D2 direction. One side of the D2 direction is referred to as the -D2 side, and the side opposite the -D2 side of the D2 direction is referred to as the +D2 side. The direction perpendicular to the D1 direction and the D2 direction is referred to as the D3 direction. The blue light LB output from the blue light output unit 101 travels toward the +D1 side along the D1 direction.

[0011] The blue light output unit 101 includes a light source 121, a light guide element 141, and a collimating element 161. The light source 121 is supported by a substrate 111. The light source 121 is provided on a +D1-side surface of the substrate 111 that is parallel to a plane including the D2 and D3 directions. The light emitting surface of the light source 121 is disposed substantially parallel to the plane including the D2 and D3 directions, and is a surface of the light source 121 opposite in the D1 direction from a surface of the light source 121 that is in contact with the +D1-side surface of the substrate 111. The light source 121 corresponds to a first light source and outputs blue light LB in a blue wavelength band within the visible wavelength band. The blue light LB diverges from the light emitting surface of the light source 121 at a predetermined radiation angle around an axis that passes through the center of the light emitting surface of the light source 121 and is parallel to the D1 direction, and is output to the +D1 side.

[0012] The light source 121 is configured, for example, by an LED that emits blue light LB. If the light source 121 is configured by an LED, the blue wavelength band is wider than when it is configured by an LD. The blue light LB in the blue wavelength band includes blue light LB1 in a first blue wavelength band and blue light LB2 in a second blue wavelength band. The blue wavelength band corresponds to the first wavelength band, for example, a wavelength band of 400 nm to 500 nm. The first blue wavelength band corresponds to the fourth wavelength band, for example, 440 nm to 500 nm. The second blue wavelength band is a wavelength band different from the first blue wavelength band, for example, 400 nm to 440 nm. The second wavelength band is closer to the ultraviolet wavelength band than the first wavelength band. The blue light LB1 corresponds to the first light.

[0013] In the blue light LB, the amount of blue light LB1 and the amount of blue light LB2 are approximately the same. The blue light LB emitted from the light source 121 is unpolarized, for example, randomly polarized, and includes multiple polarization components. The multiple polarization components include blue light LB with different polarization directions, for example, blue light LBS, which is S-polarized blue light LB, and blue light LBP, which is P-polarized blue light LB. In a description common to both blue light LB1 and LB2, blue light LB1 and LB2 may be collectively referred to as blue light LB. In a description common to both blue light LBS and LBP, blue light LBP and LBS may be collectively referred to as blue light LB.

[0014] The light source 121 may be composed of one LED or a plurality of LEDs. When the light source 121 is composed of a plurality of LEDs, the plurality of LEDs are arranged in an area occupied by the light source 121 in a plane including the D2 direction and the D3 direction.

[0015] The substrate 111 is made of, for example, metal, and also functions as a heat dissipation member that receives heat from the light source 121 that emits the blue light LB and dissipates the heat into the external space.

[0016] The light guide element 141 is provided on the optical path of the blue light LB emitted from the light source 121, and is disposed on the +D1 side of the light source 121 at a position overlapping with the light source 121 in the D2 and D3 directions. The light guide element 141 corresponds to a first light guide element, and has an incident end 141a on the −D1 side in the D1 direction, an exit end 141b on the +D1 side, and a side surface 141s and a reflecting surface 141r extending between the incident end 141a and the exit end 141b in the D1 direction.

[0017] The incident end 141a corresponds to a first incident end and extends parallel to a plane including the D2 and D3 directions. The shape of the incident end 141a when viewed from the D1 direction is the same as the shape of the light emitting surface of the light source 121 when viewed from the same direction, and is, for example, rectangular, specifically, oblong.

[0018] The size of the incident end 141a in the plane including the D2 and D3 directions may be equal to the size of the light emitting surface of the light source 121 in the plane including the D2 and D3 directions, but is preferably moderately larger than the size of the light emitting surface of the light source 121 in the plane including the D2 and D3 directions.

[0019] The exit end 141b corresponds to a first exit end, extends parallel to a plane including the D2 and D3 directions, and is larger than the entrance end 141a. The shape of the exit end 141b when viewed from the D1 direction is the same as the modulation surface of the light modulation element 181 when viewed from the same direction, and is, for example, rectangular. The size of the exit end 141b in the plane including the D2 and D3 directions is equal to the size of the modulation surface of the light modulation element 181 in the plane including the D2 and D3 directions.

[0020] The side surface 141s and the reflecting surface 141r connect the periphery of the entrance end 141a to the periphery of the exit end 141b in the direction D1.

[0021] Blue light LB emitted from the light source 121 enters the light guide element 141 from the incident end 141a. In the light guide element 141, an internal space SP141 surrounded by the incident end 141a, the exit end 141b, and the reflecting surface 141r is a region through which the blue light LB propagates. The size of the internal space SP141 in a plane including the D2 and D3 directions increases as one progresses from the −D1 side to the +D1 side in the D1 direction. The shape of the internal space SP141 in a plane including the D2 and D3 directions changes from the shape of the light-emitting surface of the light source 121 as viewed from the D1 direction to the shape of the modulation surface of the light modulation element 181 as one progresses from the −D1 side to the +D1 side.

[0022] A side surface 141s of the light guide element 141 and a reflecting surface 141r provided on the side surface 141s as described below form a predetermined angle with respect to a virtual line VX perpendicular to the incident end 141a and the optical axis, and move away from the virtual line VX within a plane including the D2 and D3 directions as they move from the -D1 side to the +D1 side. The blue light LB incident on the light guide element 141 propagates from the -D1 side to the +D1 side through an internal space SP141 surrounded by the incident end 141a, the exit end 141b, and the reflecting surface 141r.

[0023] The modulation surface of the light modulator 181 has a rectangular shape when viewed along the D1 direction, and the light emitting surface of the light source 121 has a rectangular shape when viewed along the D1 direction. The predetermined angle α, i.e., the taper angle, formed by the side surface 141s and the reflecting surface 141r, including the short side of the rectangular shape parallel to the D3 direction, with respect to the virtual line VX and the optical axis, is within a range of, for example, 7° to 22°. The predetermined angle β, i.e., the taper angle, formed by the side surface 141s and the reflecting surface 141r, including the long side of the rectangular shape parallel to the D2 direction, with respect to the virtual line VX and the optical axis, is within a range of, for example, 14° to 36°. The preferred ranges of the angles α and β are appropriately set by a numerical simulation based on the configuration of the blue light output unit 101 and ray tracing so that the reflective film 251 of the light guide element 141 has desired optical characteristics, including polarization characteristics, as will be described later.

[0024] A portion of the blue light LB incident on the light guide element 141 forms an angle with respect to the virtual line VX and the optical axis that is smaller than a predetermined angle, and does not enter the reflecting surface 141r even once, but propagates directly from the incident end 141a to the exit end 141b. The remaining portion of the blue light LB incident on the light guide element 141 forms an angle with respect to the virtual line VX and the optical axis that is equal to or larger than a predetermined angle, and enters the reflecting surface 141r from the incident end 141a one or more times, is reflected by the reflecting surface 141r, and then reaches the exit end 141b. The path of the blue light LB in the internal space SP141 varies depending on the angle of incidence on the incident end 141a, and follows multiple paths that are reflected by the reflecting surface 141r a different number of times.

[0025] The illuminance distribution of the blue light LB propagating through the internal space SP141 toward the +D1 side is uniform within a plane including the D2 and D3 directions. That is, the light-guiding element 141 uniforms the illuminance distribution of the incident blue light LB within a plane including the D2 and D3 directions. The blue light LB with its uniform illuminance distribution is emitted toward the +D1 side from the emission end 141b.

[0026] The light guide element 141 is, for example, a reflector, and is formed as a hollow member. FIG. 2 is a perspective view of the light guide element 141. As shown in FIG. 2, the light guide element 141 is formed, for example, in a rectangular shape when viewed along the D1 direction, and narrows from the exit end 141b toward the entrance end 141a. When viewed along the D1 direction, the end on the -D1 side of the frame of the reflector has the same shape and size as the entrance end 141a and the light-emitting surface of the light source 121. The end on the +D1 side of the frame of the reflector has the same shape and size as the exit end 141b and the modulation surface of the light modulation element 181, and is formed, for example, in a rectangular shape of a different size from the end on the -D1 side.

[0027] The light-guiding element 141 is composed of, for example, a plate-shaped member 241 and a reflective film 251. The plate-shaped member 241 corresponds to a first substrate. The reflective film 251 corresponds to a first reflective film. As described above, if the shapes of the incident end 141a and the exit end 141b when viewed from the D1 direction are rectangular, the reflector is composed of four trapezoidal plate-shaped members 241A, 241B, 241C, and 241D and the reflective film 251. The edges of the plate-shaped members 241A and 241C corresponding to the upper bases of the trapezoids are parallel to the D2 direction and aligned along the long sides of the incident end 141a. The edges of the plate-shaped members 241A and 241C corresponding to the lower bases of the trapezoids are parallel to the D2 direction and aligned along the long sides of the exit end 141b. The edges corresponding to the upper bases of the trapezoidal shapes of the plate-shaped members 241B and 241D are parallel to the D3 direction and are aligned along the short sides of the incident end 141a. The edges corresponding to the lower bases of the trapezoidal shapes of the plate-shaped members 241B and 241D are parallel to the D3 direction and are aligned along the short sides of the exit end 141b.

[0028] The width, i.e., dimension, of the side parallel to the D2 or D3 direction on the -D1 side corresponding to the upper base of the plate-like members 241A, 241B, 241C, and 241D is set in accordance with the size, in the D2 or D3 direction, of the incident end 141a and the light-emitting surface of the light source 121. The width, i.e., dimension, of the side parallel to the D2 or D3 direction on the +D1 side corresponding to the lower base of the plate-like members 241A, 241B, 241C, and 241D is set in accordance with the size, in the D2 or D3 direction, of the exit end 141b and the modulation surface of the light modulation element 181.

[0029] Considering the size of the light source 121, the length h1 in the D1 direction of each of the plate-like members 241A, 241B, 241C, and 241D from the incident end 141a to the exit end 141b is, for example, 5 mm to 25 mm, and preferably 8 mm to 25 mm. If the length h1 is longer than 25 mm, the reflection loss of the blue light LB in the light guide element 141 may increase excessively.

[0030] Of the four plate-shaped members 241A, 241B, 241C, and 241D, the side portion corresponding to the leg on one side of plate-shaped member 241A is connected to the side portion corresponding to the leg on one side of plate-shaped member 241B. The side portion corresponding to the leg on the other side of plate-shaped member 241B is connected to the side portion corresponding to the leg on one side of plate-shaped member 241C. The side portion corresponding to the leg on the other side of plate-shaped member 241C is connected to the side portion corresponding to the leg on one side of plate-shaped member 241D. The side portion corresponding to the leg on the other side of plate-shaped member 241D is connected to the side portion corresponding to the leg on the other side of plate-shaped member 241A.

[0031] The material of the plate-shaped member 241 does not exhibit polarization characteristics for the blue light LB, but has similar optical characteristics for the blue lights LBS and LBP, and also has similar optical characteristics for the blue lights LB1 and LB2. The material of the plate-shaped member 241 includes, for example, metals such as aluminum (Al) and silver (Ag), or glass, i.e., silicon oxide (SiO2), which is an insulating and transparent material.

[0032] When the plate-shaped member 241 is made of Al or Ag, which is a metal material, the plate-shaped member 241 increases the heat dissipation of the light guide element 141 and increases the reflectance of the blue light LB that propagates in the internal space SP141 and transmits through the reflective film 251. When the plate-shaped member 241 is made of glass, which is an insulating material and a light-transmitting material, the plate-shaped member 241 increases the heat resistance of the light guide element 141, reduces the weight of the light guide element 141, and makes it easier to process the light guide element 141. In this embodiment, it is assumed that the plate-shaped member 241 is made of glass that is light-transmitting to the blue light LB.

[0033] In the light guide element 141, a reflective film 251 is provided on a plate surface 241p facing the internal space SP141 of each of the plate-like members 241A, 241B, 241C, and 241D constituting the reflector to increase the reflectance of a predetermined polarization component of the blue light LB incident on the light guide element 141 from the incident end 141a near the side surface 141s. Of the blue light LB incident on the internal space SP141 of the light guide element 141 from the incident end 141a, S-polarized blue light LBS is reflected by the reflective film 251 and travels toward the +D1 side. In this embodiment, blue light LBS1 in a first blue wavelength band is reflected by the reflective film 251 and travels toward the +D1 side. The blue light LBS and LBS1 correspond to the first polarization component of the first light.

[0034] The intensity of the blue light LBS1 reflected by the reflective film 251 and emitted from the reflective film 251 depends on the angle of incidence of the blue light LB incident on the reflective film 251, etc. When the reflective film 251 is configured as a dichroic film, the incidence angle dependency of the intensity of the blue light LBS1 emitted from the reflective film 251 changes depending on parameters such as the thickness of each of the low refractive index layers and high refractive index layers that make up the dielectric multilayer film of the dichroic film, the number of each of the low refractive index layers and high refractive index layers, the refractive index of each of the low refractive index layers and high refractive index layers, and the difference in refractive index between the low refractive index layers and the high refractive index layers.

[0035] As described above, for example, when the angle α is within the range of 7° or more and 22° or less and the angle β is within the range of 14° or more and 36° or less, the reflective film 251 is designed and the parameters of the reflective film 251 are appropriately determined so that the incident angle of the blue light LB at which the intensity of the blue light LBS1 emitted from the reflective surface 141r and the reflective film 251 is the highest is within the range of 60° to 90°.

[0036] The reflective film 251 is, for example, a dichroic film. The dichroic film forming the reflective film 251 is composed of low refractive index layers and high refractive index layers alternately stacked along a direction perpendicular to the plate surface 241p of the plate-shaped member 241. The low refractive index layers and high refractive index layers have different refractive indices for the blue light LB. The high refractive index layers are made of, for example, titanium oxide (TiO2) or tantalum pentoxide (Ta2O5). The low refractive index layers are made of, for example, SiO2.

[0037] 3 is a cross-sectional view of light source 121, light-guiding element 141, collimating element 161, and incident-side polarizing element 171, taken along a plane including the D1 direction and the D2 direction. As shown in Fig. 3, light-guiding element 141 reflects blue light LB emitted from the light-emitting surface of light source 121 within a range of angles up to a large angle with respect to an optical axis parallel to the D1 direction, i.e., blue light LBS1 of blue light LB emitted at a wide angle, by means of reflective film 251 and propagates the blue light LBS1 in internal space SP141, thereby adjusting the beam area of ​​blue light LBS1 to the size of emission end 141b and collecting it.

[0038] The incident angle θ of the blue light LB emitted from the light source 121 and incident on the plate surface 241p of the plate-shaped member 241 and the reflective film 251 in increases from the incident end 141a to the exit end 141b in the D1 direction, that is, from the -D1 side to the +D1 side. in is the incident angle θ of the blue light LB that is incident most at the position PT1 on the -D1 side relative to the position PT2. in At least, unlike the above, the incident angle θ of the blue light LB that is most incident on the position PT1 in is greater than.

[0039] The dichroic film forming the reflective film 251 reflects at least the blue light LBS of the blue light LB emitted from the light source 121 and incident through the internal space SP141 of the light-guiding element 141. In this embodiment, the dichroic film reflects the blue light LBS1 most strongly. The blue light LBS1 reflected by the reflective film 251 reaches the exit end 141b directly or reaches the exit end 141b after being further reflected by the reflective film 251 on the +D1 side. The reflective film 251 transmits S-polarized blue light LBS2 in a second blue wavelength band and P-polarized blue light LBP of the blue light LB incident from the internal space SP141. The blue light LBS2 and LBP transmitted through the reflective film 251 are transmitted through the plate-like member 241, refracted, and emitted to the outside of the light-guiding element 141 in a plane including the D2 and D3 directions. The blue light LBP corresponds to the second polarization component of the first light.

[0040] In the blue light output unit 101 of this embodiment, the reflectance of the reflective film 251 for the blue light LBS is different from the reflectance of the reflective film 251 for the blue light LBP and is higher than the reflectance of the reflective film 251 for the blue light LBP. Furthermore, the reflectance of the reflective film 251 for the blue light LBS1 is different from the reflectance of the reflective film 251 for the blue light LBS2 and is higher than the reflectance of the reflective film 251 for the blue light LBS2. As a result, as described above, of the blue light LB entering the light-guiding element 141 from the incident end 141a, the S-polarized blue light LBS1 in the first blue wavelength band is most strongly output from the output end 141b.

[0041] When the transmittance of the reflective film 251 and the plate-like member 241 for the blue light LBS2, LBP is higher than the absorptance, the amount of the blue light LBS2, LBP absorbed by the reflective film 251 and the plate-like member 241 is reduced, and heat is less likely to accumulate in the light-guiding element 141. This prevents the light-guiding element 141 from changing shape or being distorted due to heat, and suppresses deterioration of the light-guiding element 141 over time.

[0042] Incident angle θ of the reflective film 251 inThe reflectance and transmittance for each of the incident blue light beams LBS1, LBS2, and LBP are adjusted by parameters such as the thickness of each of the low refractive index layers and high refractive index layers of the dielectric multilayer film that constitutes the dichroic film, the number of each of the low refractive index layers and high refractive index layers, the refractive index of each of the low refractive index layers and high refractive index layers, and the refractive index difference between the low refractive index layers and the high refractive index layers, and are appropriately set so that the blue light beam LBS1 is guided to the exit end 141b with high efficiency.

[0043] The incident angle θ of the blue light LB on the reflecting surface 141r and the reflecting film 251 in and the intensity of the blue light LB emitted from the reflecting surface 141r and the reflecting film 251 can be obtained by a numerical simulation based on the configuration and ray tracing of the blue light emitting unit 101. The parameters of the dielectric multilayer film constituting the dichroic film of the reflecting film 251 are set as the incident angle θ of the blue light LB from the internal space SP141. in For example, as mentioned above, the incident angle θ of the blue light LB that is most incident on the +D1 side is in is the incident angle θ of the blue light LB that is most incident on the -D1 side in Therefore, in the light-guiding element 141, the film thickness of the reflective film 251 on the side of the exit end 141b, i.e., the +D1 side, of the center position PTC in the D1 direction in the direction along the optical axis of the blue light LB is greater than the film thickness of the reflective film 251 on the side of the entrance end 141a, i.e., the -D1 side, of the position PTC in the D1 direction.

[0044] As described above, the reflectance, transmittance, and absorptance of the light-guiding element 141 for the blue light LB, and the parameters of the dielectric multilayer film of the dichroic film that forms the reflective film 251 are set, so the amount of blue light LBS2, LBP emitted from the emission end 141b of the light-guiding element 141 is less than the amount of blue light LBS1 emitted from the emission end 141b of the light-guiding element 141.

[0045] 1 and 3, the collimating element 161 is provided on the optical path of the blue light LBS1 emitted from the light-guiding element 141, and is disposed on the +D1 side of the light-guiding element 141 and at a position overlapping with the light-guiding element 141 in the D2 and D3 directions. The collimating element 161 collimates the blue light LBS1 emitted from the light-guiding element 141 along the D1 direction.

[0046] The collimating element 161 is, for example, a plano-convex lens, and has an incident surface formed of a flat surface perpendicular to the D1 direction and an exit surface formed of a convex curved surface protruding toward the exit side of the blue light LBS1. The focal point of the plano-convex lens constituting the collimating element 161 is at least on the -D1 side of the collimating element 161, is opposite the +D1 side from which the blue light LBS1 is exited from the collimating element 161, and is further on the -D1 side of the light-guiding element 141. The incident surface of the plano-convex lens of the collimating element 161 is in contact with the exit end 141b of the light-guiding element 141. By having the collimating element 161 in contact with the exit end 141b, the blue light LBS1 exited from the exit end 141b of the light-guiding element 141 is taken in by the collimating element 161 to the maximum extent, thereby minimizing loss of the blue light LBS1. However, the collimating element 161 may be an optical lens other than a plano-convex lens that can collimate the incident blue light LBS1, and may be disposed at an appropriate distance from the light guide element 141 in the D1 direction.

[0047] The incident-side polarizing element 171 is provided on the optical path of the blue light LBS1 emitted from the collimating element 161, and is disposed on the +D1 side of the collimating element 161 and at a position overlapping with the collimating element 161 in the D2 and D3 directions. The incident-side polarizing element 171 is in contact with the light modulation element 181 from the -D1 side, for example, but may be disposed at an appropriate distance from the light modulation element 181 in the D1 direction. The incident-side polarizing element 171 emits a predetermined polarized light of the blue light LB emitted from the collimating element 161 toward the +D1 side along the D1 direction. The predetermined polarized light is, for example, S-polarized light.

[0048] The incident-side polarizing element 171 is, for example, a reflective polarizing plate or an absorptive polarizing plate having a plate surface parallel to a plane including the D2 and D3 directions. The incident-side polarizing element 171 transmits a portion of the incident blue light LB having a predetermined polarization to the +D1 side, and reflects or absorbs the other portion of the blue light LB to the -D1 side. Note that, if it is desired to suppress return light and stray light to the light source 121, it is desirable that the incident-side polarizing element 171 be an absorptive polarizing plate.

[0049] In the blue light LB emitted from the exit end 141b of the light-guiding element 141, the amount of blue light LBP is significantly smaller than the amount of blue light LBS. Therefore, the less change or disturbance in polarization of the blue light LB in the D1 direction after it is emitted from the exit end 141b of the light-guiding element 141 and passes through the collimating element 161 before it is incident on the entrance surface of the entrance-side polarizing element 171, the more the amount of blue light LBP reflected to the -D1 side by the entrance-side polarizing element 171 or absorbed by the entrance-side polarizing element 171 is minimized. This reduces the load on the entrance-side polarizing element 171 and suppresses thermal degradation of the entrance-side polarizing element 171.

[0050] Light modulation element 181 is provided on the optical path of blue light LB emitted from incident-side polarizing element 171, and is disposed on the +D1 side of incident-side polarizing element 171 at a position overlapping with incident-side polarizing element 171 in the D2 and D3 directions. Light modulation element 181 corresponds to a first light modulation element, and modulates blue light LB1 in a first blue wavelength band of blue light LB based on image information transmitted from an image forming device, such as a computer (not shown), connected to light modulation element 181 from the outside. Blue light LB2 in a second blue wavelength band of blue light LB is color light that is not to be converted into image light by light modulation element 181, and does not contribute to the predetermined color balance of the image projected by projector 301.

[0051] The light modulation element 181 is, for example, a transmissive liquid crystal panel. The liquid crystal panel constituting the light modulation element 181 has a plurality of pixels (not shown). Each pixel has a switching element. The switching element is, for example, a polysilicon thin film transistor (TFT). An electrical signal corresponding to the brightness of blue light at the relative position of each pixel on the modulation surface of the light modulation element 181 in the image projected by the projector 301 is supplied to the switching element of each pixel. Each pixel modulates the vibration direction of blue light LBS1 incident from the incident-side polarizing element 171 by the operation of the switching element in response to the electrical signal, thereby generating blue image light IB. The image light IB corresponds to the light emitted from the first light modulation element. The light modulation element 181 emits the image light IB generated by the liquid crystal panel toward the +D1 side along the D1 direction.

[0052] 1, the exit-side polarizing element 175 is provided on the optical path of the image light IB exiting from the light modulation element 181, and is disposed on the +D1 side of the light modulation element 181 and at a position overlapping with the light modulation element 181 in the D2 and D3 directions. The exit-side polarizing element 175 is in contact with the light modulation element 181 from the +D1 side, for example, but may be disposed at an appropriate distance from the light modulation element 181 in the D1 direction. The exit-side polarizing element 175 exits a predetermined polarized light of the image light IB exiting from the light modulation element 181 along the D1 direction to the +D1 side. The predetermined polarized light is, for example, P-polarized light.

[0053] The exit-side polarizing element 175 is, for example, a reflective polarizing plate or an absorptive polarizing plate having a plate surface parallel to a plane including the D2 direction and the D3 direction. The exit-side polarizing element 175 transmits a portion of the incident image light IB containing a predetermined polarization to the +D1 side, and reflects or absorbs another portion of the image light IB to the -D1 side. Note that, when it is desired to suppress return light and stray light to the light modulation element 181, it is desirable to employ an absorptive polarizing plate as the exit-side polarizing element 175.

[0054] The green light emitting portion 102 is disposed on the +D1 side and the -D2 side of the blue light emitting portion 101, and is disposed in a region overlapping with the blue light emitting portion 101 in the D3 direction. The green light emitting portion 102 emits green light LG. The green light LG emitted from the green light emitting portion 102 travels toward the +D2 side along the D2 direction.

[0055] The green light emitting unit 102 includes a light source 122 , a light guide element 142 , and a collimating element 162 .

[0056] The light source 122 is supported by the substrate 112. The light source 122 is provided on the +D2 side of the surface of the substrate 112 that is parallel to a plane including the D1 and D3 directions. The light emitting surface 122a of the light source 122 is disposed approximately parallel to the plane including the D1 and D3 directions, and is the surface of the light source 122 on the opposite side in the D2 direction from the surface of the light source 122 that is in contact with the +D2 side of the substrate 112. The light source 122 corresponds to a second light source, and emits green light LG in the green wavelength band in the visible wavelength band.

[0057] 4 is a cross-sectional view of light source 122, light-guiding element 142, collimating element 162, and incident-side polarizing element 172, and corresponds to a view when cut along a plane including the D1 direction and the D2 direction. As shown in FIG. 4, in green light emitting unit 102, in order to optimize the blue wavelength band and intensity of blue light LB emitted by blue light emitting unit 101 and the green wavelength band and intensity of green light LG relative to the red wavelength band and intensity of red light LR emitted by red light emitting unit 103, light source 122 is composed of an LED with a built-in phosphor, and has LED body 125 made of a semiconductor and phosphor 124.

[0058] The LED body 125 is provided on the +D2 side surface of the substrate 112. The LED body 125 may be, for example, an LED that emits blue light LB3 in a blue wavelength band. The blue wavelength band of the blue light LB3 emitted from the LED body 125 is included in the blue wavelength band of the blue light LB emitted from the light source 121.

[0059] The phosphor 124 is laminated on the light-emitting surface 125a on the +D2 side of the LED body 125. The phosphor 124 is excited by at least a portion of the light emitted from the LED body 125 as excitation light, and emits green light LG as fluorescence from the emission surface 124a. The type and material of the LED body 125 and the type and material of the phosphor 124 are appropriately selected so that the phosphor 124 excited by the light emitted from the LED body 125 emits green light LG in the green wavelength band.

[0060] The green light LG in the green wavelength band, which is fluorescence emitted from the phosphor 124, corresponds to the second light. The green wavelength band corresponds to the second wavelength band. The green wavelength band of the green light LG emitted from the phosphor 124 is wider than the green wavelength band of the green light emitted from the LD. The green wavelength band is, for example, a wavelength band of 500 nm to 590 nm.

[0061] Another portion of the excitation light that is emitted from the LED body 125 and not converted into fluorescence by the phosphor 124 is emitted from the emission surface 124a to the +D2 side together with the green light LG. The other portion of the excitation light is, for example, blue light LB3 in the blue wavelength band. The blue wavelength band of the blue light LB3 is a wavelength band different from the green wavelength band of the green light LG and corresponds to a fourth wavelength band, for example, 450 nm to 490 nm. The amount of the blue light LB3 is approximately the same as or less than the amount of the green light LG.

[0062] The green light LG and blue light LB3 emitted from the light source 122 are unpolarized, for example, randomly polarized, and include multiple polarization components. The multiple polarization components of the green light LG include green light LG with different polarization directions, for example, green light LGS, which is S-polarized, and green light LGP, which is P-polarized. The multiple polarization components of the blue light LB3 include blue light LB3 with different polarization directions, for example, blue light LBS3, which is S-polarized, and blue light LBP3, which is P-polarized.

[0063] As described above, when the LED body 125 emits blue light LB, the phosphor 124 is, for example, a light-transmitting ceramic material such as cerium-doped yttrium aluminum garnet (YAG:Ce 3+ ) may also be included.

[0064] In the light source 122, the LED body 125 may be configured with one LED or may be configured with a plurality of LEDs as a whole, similar to the light source 121. When the LED body 125 is configured with a plurality of LEDs, the plurality of LEDs are arranged in an area occupied by the LED body 125 in a plane including the D1 direction and the D3 direction.

[0065] The substrate 112 is made of, for example, metal, and also functions as a heat dissipation member that receives heat from the light source 122 that emits the green light LG and the blue light LB3 and dissipates the heat to the external space.

[0066] The light guide element 142 is provided on the optical path of the green light LG and the blue light LB3 emitted from the light source 122, and is disposed on the +D2 side of the light source 122 at a position overlapping with the light source 122 in the D1 and D3 directions. The light guide element 142 corresponds to a second light guide element, and has an incident end 142a on the −D2 side in the D2 direction, an exit end 142b on the +D2 side, and a side surface 142s and a reflecting surface 142r extending between the incident end 142a and the exit end 142b in the D2 direction.

[0067] The incident end 142a corresponds to a second incident end and extends parallel to a plane including the D1 and D3 directions. The shape of the incident end 142a when viewed from the D2 direction is the same as the shape of the light emitting surface 122a of the light source 122 when viewed from the same direction, and is, for example, rectangular, specifically, oblong.

[0068] The size of the incident end 142a in the plane including the D1 and D3 directions may be equal to the size of the light-emitting surface 122a of the light source 122 in the plane including the D1 and D3 directions, but is preferably suitably larger than the size of the light-emitting surface 122a in the plane including the D1 and D3 directions.

[0069] The exit end 142b corresponds to a second exit end, extends parallel to a plane including the D1 and D3 directions, and is larger than the entrance end 142a. The shape of the exit end 142b when viewed from the D2 direction is the same as the modulation surface of the light modulation element 182 when viewed from the same direction, and is, for example, rectangular. The size of the exit end 142b in the plane including the D1 and D3 directions is equal to the size of the modulation surface of the light modulation element 182 in the plane including the D1 and D3 directions.

[0070] The side surface 142s and the reflecting surface 142r connect the periphery of the entrance end 142a to the periphery of the exit end 142b in the direction D2.

[0071] The green light LG and blue light LB3 emitted from the light source 122 enter the light-guiding element 142 from the incident end 142a. In the light-guiding element 142, an internal space SP142 surrounded by the incident end 142a, the exit end 142b, and the reflecting surface 142r is a region through which at least a portion of the green light LG and the blue light LB3 propagate. The size of the internal space SP142 in a plane including the D1 and D3 directions increases as one progresses from the −D2 side to the +D2 side in the D2 direction. Furthermore, the shape of the internal space SP142 in a plane including the D1 and D3 directions changes from the shape of the light-emitting surface 122a of the light source 122 as viewed from the D2 direction to the shape of the modulation surface of the light modulation element 182 as one progresses from the −D2 side to the +D2 side.

[0072] A side surface 142s of the light-guiding element 142 and a reflecting surface 142r provided on the side surface 142s as described below form a predetermined angle with respect to the optical axis and a virtual line VX perpendicular to the incident end 142a, and move away from the virtual line VX within a plane including the D2 and D3 directions as the light moves from the -D2 side to the +D2 side. The green light LG incident on the light-guiding element 142 propagates through the internal space SP142 from the -D2 side to the +D2 side.

[0073] The modulation surface of the light modulation element 182 has a rectangular shape when viewed along the D2 direction, and the light-emitting surface 122a of the light source 122 has a rectangular shape when viewed along the D2 direction. The predetermined angle α formed by the side surface 142s and the reflecting surface 142r of the rectangular shape, including the short side parallel to the D3 direction, with respect to the virtual line VX and the optical axis, is, for example, within a range of 7° to 22°. The predetermined angle β formed by the side surface 141s and the reflecting surface 141r of the rectangular shape, including the long side parallel to the D2 direction, with respect to the virtual line and the optical axis, is, for example, within a range of 14° to 36°. The preferred ranges of the angles α and β are appropriately set by a numerical simulation based on the configuration of the green light output unit 102 and ray tracing so that the reflective film 252 of the light guide element 142 has optical characteristics including desired polarization characteristics, as will be described later.

[0074] A portion of the green light LG and a portion of the blue light LB3 that enter the light-guiding element 142 form an angle with respect to the virtual line VX and the optical axis that is smaller than angle α or angle β, and do not enter the reflecting surface 142r even once, but propagate directly from the incident end 142a to the exit end 142b. The remaining portions of the green light LG and the remaining portions of the blue light LB3 that enter the light-guiding element 142 form an angle with respect to the virtual line VX and the optical axis that is equal to or larger than angle α or angle β, and enter the reflecting surface 142r from the incident end 142a one or more times, are reflected by the reflecting surface 142r, and then reach the exit end 142b. The paths of the green light LG and the blue light LB3 in the internal space SP142 vary depending on the angle of incidence on the incident end 142a, and follow multiple paths that are reflected by the reflecting surface 142r a different number of times.

[0075] The illuminance distribution of the green light LG and the blue light LB3 propagating through the internal space SP142 is uniformed within a plane including the D1 and D3 directions. That is, the light-guiding element 142 uniforms the illuminance distribution of the incident green light LG within a plane including the D1 and D3 directions. The green light LG and the blue light LB3 with uniform illuminance distribution are emitted from the exit end 142b toward the +D2 side.

[0076] The light guide element 142 is a hollow reflector made of a plate-like member, similar to the light guide element 141. When viewed along the D2 direction, the end on the -D2 side of the frame of the reflector has the same shape and size as the incident end 142a and the light emitting surface 122a of the light source 122, and is formed, for example, in a rectangular shape. The end on the +D2 side of the frame of the reflector has the same shape and size as the exit end 142b and the modulation surface of the light modulation element 182, and is formed, for example, in a rectangular shape with a different size from the end on the -D2 side.

[0077] The light guide element 142 is composed of a plate-shaped member 242 and a reflective film 252. The plate-shaped member 242 corresponds to a second base material. The reflective film 252 corresponds to a second reflective film. Like the light guide element 141, the light guide element 142 is composed of four trapezoidal plate-shaped members 242, each with its legs connected to one another. The widths, i.e., dimensions, of the sides parallel to the D1 or D3 direction on the -D2 side, which correspond to the upper bases of the four plate-shaped members 242, are set according to the size of the incident end 142a and the light-emitting surface 122a in the D1 or D3 direction. The widths, i.e., dimensions, of the sides parallel to the D1 or D3 direction on the +D2 side, which correspond to the lower bases of the four plate-shaped members 242, are set according to the size of the exit end 142b and the modulation surface of the light modulation element 182 in the D1 or D3 direction.

[0078] Considering the size of the light source 122, the length of the plate-shaped member 242 in the direction D2 from the incident end 142a to the exit end 142b is 5 mm to 25 mm, and preferably 8 mm to 25 mm. If the length of the plate-shaped member 242 in the direction D2 is longer than 25 mm, the reflection loss of the green light LG and the blue light LB3 in the light-guiding element 142 may increase excessively.

[0079] Of the four plate-shaped members 242, a side portion corresponding to a leg on one side of a first plate-shaped member 242 is connected to a side portion corresponding to a leg on one side of a second plate-shaped member 242. A side portion corresponding to a leg on the other side of the second plate-shaped member 242 is connected to a side portion corresponding to a leg on one side of a third plate-shaped member 242. A side portion corresponding to a leg on the other side of the third plate-shaped member 242 is connected to a side portion corresponding to a leg on one side of a fourth plate-shaped member 242. A side portion corresponding to a leg on the other side of the fourth plate-shaped member 242 is connected to a side portion corresponding to a leg on the other side of the first plate-shaped member 242.

[0080] The material of the plate-shaped member 242 does not exhibit polarization characteristics for the green light LG and the blue light LB3, and has similar optical characteristics for the green light LGS, LGP and the blue light LBS3, LBP3. The material of the plate-shaped member 242 includes, for example, Al, Ag, or glass, and is, for example, the same as the material of the plate-shaped member 241.

[0081] When the plate-shaped member 242 is made of Al or Ag, the plate-shaped member 242 improves the heat dissipation of the light-guiding element 142 and also improves the reflectance of the green light LG and the blue light LB3 that propagate in the internal space SP142 and transmit through the reflective film 251. When the plate-shaped member 242 is made of glass, the plate-shaped member 242 improves the heat resistance of the light-guiding element 142, reduces the weight of the light-guiding element 142, and facilitates processing of the light-guiding element 142. In this embodiment, it is assumed that the plate-shaped member 242 is made of glass that is translucent to the green light LG and the blue light LB3.

[0082] In the reflector of the light-guiding element 142, a reflective film 252 is provided on the plate surface opposite the side surface 142s of the plate-shaped member 242 constituting the reflector, i.e., on the plate surface 242p facing the internal space SP142, in order to increase the reflectance of predetermined polarization components of the green light LG and blue light LB3 incident on the light-guiding element 142 from the incident end 142a. The S-polarized green light LGS of the green light LG and the S-polarized blue light LBS3 of the blue light LB3 incident on the internal space SP142 of the light-guiding element 142 from the incident end 142a are reflected by the reflective film 252 and travel toward the +D2 side. In this embodiment, the green light LGS of the green light LGS and the blue light LBS3 is reflected by the reflective film 252 and travels toward the +D2 side. The green light LGS corresponds to the first polarization component of the second light.

[0083] The intensities of the green light LGS and the blue light LBS3 reflected by and emitted from the reflective film 252 depend on the angles of incidence of the green light LG and the blue light LB3 incident on the reflective film 252. When the reflective film 252 is configured as a dichroic film, the incidence angle dependence of the intensities of the green light LGS and the blue light LBS3 emitted from the reflective film 252 changes depending on parameters such as the thickness of each of the low refractive index layers and the high refractive index layers that make up the dielectric multilayer film of the dichroic film, the number of each of the low refractive index layers and the high refractive index layers, the refractive index of each of the low refractive index layers and the high refractive index layers, and the difference in refractive index between the low refractive index layers and the high refractive index layers.

[0084] As described above, for example, when the angle α is within the range of 7° or more and 22° or less and the angle β is within the range of 14° or more and 36° or less, the reflective film 252 is designed and the parameters of the reflective film 252 are appropriately determined so that the incident angle of the green light LG and the blue light LB3 at which the intensities of the green light LGS and the blue light LBS3 emitted from the reflective surface 142r and the reflective film 252 are highest is within the range of 60° to 90°.

[0085] The reflective film 252 is, for example, a dichroic film. The dichroic film forming the reflective film 252 is composed of low-refractive index layers and high-refractive index layers alternately stacked along a direction perpendicular to the plate surface 242p of the plate-shaped member 242. The low-refractive index layers and high-refractive index layers have different refractive indices for the green light LG and different refractive indices for the blue light LB3. The high-refractive index layers are made of, for example, TiO2 or Ta2O5. The low-refractive index layers are made of, for example, SiO2.

[0086] The light-guiding element 142 reflects the green light LG and blue light LB3 emitted from the light-emitting surface of the light source 122 within a large angle range relative to the optical axis, i.e., the green light LGS of the green light LG and blue light LB3 emitted at a wide angle, by the reflective film 252, and propagates the light in the internal space SP142, thereby adjusting and collecting the beam area of ​​the green light LGS to the size of the emission end 141b.

[0087] The angle of incidence θ of the green light LG and the blue light LB3 incident on the plate surface 242p of the plate-shaped member 242 and the reflective film 252 from the light source 122 in increases in the D2 direction from the entrance end 142a to the exit end 142b, that is, from the −D2 side to the +D2 side.

[0088] The dichroic film forming the reflective film 252 reflects at least the green light LGS of the green light LG emitted from the light source 122 and incident from the internal space SP142 of the light-guiding element 142, and at least the blue light LBS3 of the blue light LB3. In this embodiment, the dichroic film reflects the green light LGS most strongly. The green light LGS reflected by the reflective film 252 reaches the exit end 142b directly or reaches the exit end 142b after being further reflected by the reflective film 252 on the +D2 side. The reflective film 252 transmits S-polarized blue light LBS3 in the third blue wavelength band of the green light LG and blue light LB3 incident from the internal space SP142, and P-polarized green light LGP. The blue light LBS3 and green light LGP transmitted through the reflective film 252 are transmitted through the plate-like member 242, refracted, and emitted to the outside of the light-guiding element 142 in a plane including the D1 and D3 directions. The green light LGP corresponds to the second polarization component of the second light.

[0089] In the green light output unit 102 of the present embodiment, the reflectance of the reflective film 252 for the green light LGS is different from the reflectance of the reflective film 252 for the green light LGP and is higher than the reflectance of the reflective film 252 for the green light LGP. Furthermore, the reflectance of the reflective film 252 for the green light LGS is different from the reflectance of the reflective film 252 for the blue light LBS3 and is higher than the reflectance of the reflective film 252 for the blue light LBS3. As a result, as described above, of the green light LG and blue light LB3 incident on the light-guiding element 142 from the incident end 142a, the S-polarized green light LGS is most strongly output from the output end 142b.

[0090] When the transmittance of the reflective film 252 and the plate-shaped member 242 for the blue light LBS3 and the green light LGP is higher than the absorptance, the blue light LBS3 and the green light LGP absorbed by the reflective film 252 and the plate-shaped member 242 is reduced, and heat is less likely to accumulate in the light-guiding element 142. This prevents the light-guiding element 142 from changing shape or being distorted due to heat, and suppresses deterioration of the light-guiding element 142 over time.

[0091] Incident angle θ of the reflective film 252 inThe reflectance and transmittance for each of the blue light LBS3 and green light LGP incident at the end 142b are adjusted by parameters such as the thickness of each of the low refractive index layers and high refractive index layers of the dielectric multilayer film that constitutes the dichroic film, the number of each of the low refractive index layers and high refractive index layers, the refractive index of each of the low refractive index layers and high refractive index layers, and the refractive index difference between the low refractive index layers and the high refractive index layers, and are appropriately set so that the green light LGS1 is guided to the exit end 142b with high efficiency.

[0092] The angle of incidence θ of the green light LG and the blue light LB3 on the reflecting surface 142r and the reflecting film 252 in and the intensities of the green light LG and blue light LB3 emitted from the reflecting surface 142r and the reflecting film 252 are also obtained by a numerical simulation based on the configuration and ray tracing of the green light emitting unit 102. The parameters of the dielectric multilayer film constituting the dichroic film of the reflecting film 252 are determined by the incident angle θ in For example, as mentioned above, the incident angle θ of the green light LG and blue light LB3 that are most frequently incident on the +D2 side is in is the incident angle θ of the green light LG and blue light LB3 that are most incident on the -D2 side. in Therefore, in the light-guiding element 142, the film thickness of the reflective film 252 on the side of the exit end 142b, i.e., the +D2 side, of the center position PTC in the direction along the optical axis of the green light LG, i.e., the D2 direction, is greater than the film thickness of the reflective film 252 on the side of the entrance end 142a, i.e., the -D2 side, of the center position PTC in the D2 direction.

[0093] As described above, the reflectance, transmittance, and absorptance of the light-guiding element 142 for the green light LG and the blue light LB3, and the parameters of the dielectric multilayer film of the dichroic film that forms the reflective film 252 are set, so the amount of blue light LB3 and the amount of green light LGP emitted from the emission end 142b of the light-guiding element 142 are less than the amount of green light LGS emitted from the emission end 142b of the light-guiding element 142.

[0094] 1 and 4, the collimating element 162 is provided on the optical path of the green light LGS emitted from the light guide element 142, and is disposed on the +D2 side of the light guide element 142 and at a position overlapping with the light guide element 142 in the D1 and D3 directions. The collimating element 162 collimates the green light LGS emitted from the light guide element 142 along the D2 direction.

[0095] The collimating element 162 is, for example, a plano-convex lens, and has an incident surface formed of a flat surface perpendicular to the D2 direction and an exit surface formed of a convex curved surface protruding toward the exit side of the green light LGS. The focal point of the plano-convex lens constituting the collimating element 162 is at least on the -D2 side of the collimating element 162, is opposite to the +D2 side from which the green light LGS is exited from the collimating element 162, and is further on the -D2 side of the light-guiding element 142. The incident surface of the collimating element 162 is in contact with the exit end 142b of the light-guiding element 142. By having the collimating element 162 in contact with the exit end 142b, the green light LGS exited from the exit end 142b of the light-guiding element 142 is taken in by the collimating element 162 to the maximum extent, thereby minimizing loss of the green light LGS. However, the parallelizing element 162 may be an optical lens other than a plano-convex lens that can parallelize the incident green light LGS, and may be disposed at an appropriate distance from the light-guiding element 142 in the D2 direction.

[0096] The incident-side polarizing element 172 is provided on the optical path of the green light LGS emitted from the collimating element 162, and is disposed on the +D2 side of the collimating element 162, and at a position overlapping with the collimating element 162 in the D1 and D3 directions. The incident-side polarizing element 172 is in contact with the light modulation element 182 from the +D2 side, for example, but may be disposed with an appropriate gap between it and the light modulation element 182 in the D2 direction. The incident-side polarizing element 172 emits a predetermined polarized light of the green light LG emitted from the collimating element 162 toward the +D2 side along the D2 direction. The predetermined polarized light is, for example, S-polarized light.

[0097] The incident-side polarizing element 172 is, for example, a reflective polarizing plate or an absorptive polarizing plate having a plate surface parallel to a plane including the D1 and D3 directions. The incident-side polarizing element 172 transmits a portion of the incident green light LG that has a predetermined polarization to the +D2 side, and reflects or absorbs the other portion of the green light LG to the -D2 side.

[0098] Incidentally, if it is desired to suppress stray light and return light to light source 122, it is desirable that incident-side polarizing element 172 be an absorptive polarizing plate. However, if light source 122 has phosphor 124, as in green light emitting unit 102, incident-side polarizing element 172 may be a reflective polarizing plate because light reflected from the reflective polarizing plate can be utilized to excite phosphor 124.

[0099] Of the green light LG and blue light LB3 emitted from the exit end 142b of the light-guiding element 142, the amount of P-polarized green light LGP and blue light LBP3 is significantly reduced compared to the amount of S-polarized green light LGS and blue light LBS3. Therefore, the less change or disturbance in polarization of the green light LG and blue light LB3 in the D2 direction after they are emitted from the exit end 142b of the light-guiding element 142, pass through the collimating element 162, and enter the incident surface of the incident-side polarizing element 172, the more effectively the amount of green light LGP and blue light LBP3 reflected to the -D2 side by the incident-side polarizing element 172 or absorbed by the incident-side polarizing element 172 is reduced. This reduces the load on the incident-side polarizing element 172, and suppresses thermal degradation of the incident-side polarizing element 172.

[0100] The green light LGP reflected from the incident-side polarizing element 172 toward the -D2 side passes sequentially through the collimating element 162 and the light-guiding element 142, travels along the D2 direction toward the -D2 side, is collected within a plane including the D1 and D3 directions, and enters the phosphor 124 of the light source 122 from the +D2 side. The phosphor 124 is re-excited by the green light LGP emitted from the incident-side polarizing element 172 toward the -D2 side, and emits green light LG containing the green light LGS and LGP again toward the +D2 side from the emission surface 124a. Because the incident-side polarizing element 172 is configured as a reflective polarizing plate, the polarized light of the green light LG that does not pass through the incident-side polarizing element 172 re-enters the phosphor 124 of the light source 122 and contributes to the excitation and light emission of the phosphor 124.

[0101] Light modulation element 182 is provided on the optical path of green light LG emitted from incident-side polarizing element 172, and is disposed on the +D2 side of incident-side polarizing element 172 at a position overlapping with incident-side polarizing element 172 in the D1 and D3 directions. Light modulation element 182 corresponds to a second light modulation element, and modulates green light LG in the green wavelength band out of green light LG and blue light LB3, based on image information transmitted from an external image forming device such as a computer (not shown) connected to light modulation element 182. Blue light LB3 is a color light that is not to be converted into image light by light modulation element 182, and does not contribute to the predetermined color balance of the image projected by projector 301.

[0102] The light modulation element 182 is, for example, a transmissive liquid crystal panel. The liquid crystal panel constituting the light modulation element 182 has a plurality of pixels (not shown). Each pixel is equipped with a switching element. The switching element is, for example, a TFT. An electrical signal corresponding to the brightness of green light at the relative position of each pixel on the modulation surface of the light modulation element 182 in the image projected by the projector 301 is supplied to the switching element of each pixel. Each pixel modulates the vibration direction of green light LGS incident from the incident-side polarizing element 172 by the operation of the switching element in response to the electrical signal, thereby generating green image light IG. The image light IG corresponds to the light emitted from the second light modulation element. The light modulation element 182 emits the image light IG generated by the liquid crystal panel toward the +D2 side along the D2 direction.

[0103] 1, the exit-side polarizing element 176 is provided on the optical path of the image light IG exiting from the light modulation element 182, and is disposed on the +D2 side of the light modulation element 182 and at a position overlapping with the light modulation element 182 in the D1 direction and the D3 direction. The exit-side polarizing element 176 is in contact with the light modulation element 182 from the +D2 side, for example, but may be disposed with an appropriate gap between it and the light modulation element 182 in the D2 direction. The exit-side polarizing element 176 exits a predetermined polarized light of the image light IG exiting from the light modulation element 182 toward the +D2 side along the D2 direction. The predetermined polarized light is, for example, P-polarized light.

[0104] The exit-side polarizing element 176 is, for example, a reflective polarizing plate or an absorptive polarizing plate having a plate surface parallel to a plane including the D1 direction and the D3 direction. The exit-side polarizing element 176 transmits a portion of the incident image light IG that contains a predetermined polarization to the +D2 side, and reflects or absorbs the other portion of the image light IG to the -D2 side. Note that, if it is desired to suppress return light and stray light to the light modulation element 182, it is desirable to employ an absorptive polarizing plate as the exit-side polarizing element 176.

[0105] The red light emitting portion 103 is disposed on the +D1 side of the green light emitting portion 102, and is disposed in a region overlapping with the blue light emitting portion 101 in the D2 and D3 directions. The red light emitting portion 103 emits red light LR. The red light LR emitted from the red light emitting portion 103 travels toward the -D1 side along the D1 direction.

[0106] The red light emitting unit 103 has a light source 123, a light-guiding element 143, and a collimating element 163. The light source 123 is supported by the substrate 113. The light source 123 is provided on a plate surface on the -D1 side of the plate surface of the substrate 113 that is parallel to a plane including the D2 and D3 directions. The light emitting surface of the light source 123 is disposed approximately parallel to the plane including the D2 and D3 directions, and is a surface of the light source 123 on the opposite side in the D1 direction from a surface of the light source 123 that is in contact with the plate surface on the +D2 side of the substrate 113. The light source 123 corresponds to a third light source, and emits red light LR in the red wavelength band in the visible wavelength band.

[0107] The light source 123 is configured, for example, by an LED that emits red light LR. If the light source 123 is configured by an LED, the red wavelength band is wider than when it is configured by an LD. The red wavelength band is, for example, a wavelength band of 590 nm to 700 nm. The red light LR corresponds to the third light.

[0108] The red light LR emitted from the light source 123 is unpolarized, for example, randomly polarized, and includes multiple polarization components. The multiple polarization components include red light LR with mutually different polarization directions, for example, red light LRS which is S-polarized light of the red light LR, and red light LRP which is P-polarized light. In the description common to the red light LRS and LRP, the red light LRP and LRS may also be collectively referred to as red light LR.

[0109] The light source 123 may be composed of one LED or a plurality of LEDs. When the light source 123 is composed of a plurality of LEDs, the plurality of LEDs are arranged in an area occupied by the light source 123 in a plane including the D2 direction and the D3 direction.

[0110] The substrate 113 is made of, for example, metal, and also functions as a heat dissipation member that receives heat from the light source 123 that emits the red light LR and dissipates the heat into the external space.

[0111] 5 is a cross-sectional view of the light source 123, the light guide element 143, the collimating element 163, and the incident-side polarizing element 173, taken along a plane including the D1 and D2 directions. As shown in FIG. 5, the light guide element 143 is provided on the optical path of the red light LR emitted from the light source 123, and is disposed on the -D1 side of the light source 123 and at a position overlapping with the light source 123 in the D2 and D3 directions. The light guide element 143 corresponds to a third light guide element and has an incident end 143a on the +D1 side in the D1 direction, an exit end 143b on the -D1 side, and a side surface 143s and a reflecting surface 143r extending between the incident end 143a and the exit end 143b in the D1 direction.

[0112] Incident end 143a corresponds to a third incident end and extends parallel to a plane including directions D2 and D3. The shape of incident end 143a when viewed from direction D1 is the same as the shape of the light emitting surface of light source 123 when viewed from the same direction, and is, for example, rectangular, specifically, oblong.

[0113] The size of the incident end 143a in the plane including the D2 and D3 directions may be equal to the size of the light-emitting surface of the light source 123 in the plane including the D2 and D3 directions, but is preferably suitably larger than the size of the light-emitting surface of the light source 123 in the plane including the D2 and D3 directions.

[0114] The exit end 143b corresponds to a third exit end, extends parallel to a plane including the D2 and D3 directions, and is larger than the entrance end 143a. The shape of the exit end 143b when viewed from the D1 direction is the same as the modulation surface of the light modulation element 183 when viewed from the same direction, and is, for example, rectangular. The size of the exit end 143b in the plane including the D2 and D3 directions is equal to the size of the modulation surface of the light modulation element 183 in the plane including the D2 and D3 directions.

[0115] The side surface 143s and the reflecting surface 143r connect the periphery of the entrance end 143a to the periphery of the exit end 143b in the direction D1.

[0116] The red light LR emitted from the light source 123 enters the light-guiding element 143 from the incident end 143a. In the light-guiding element 143, an internal space SP143 surrounded by the incident end 143a, the exit end 143b, and the reflecting surface 143r is a region through which the red light LR propagates. The size of the internal space SP143 in a plane including the D2 and D3 directions increases as one progresses from the +D1 side to the -D1 side in the D1 direction. The shape of the internal space SP143 in a plane including the D2 and D3 directions changes from the shape of the light-emitting surface of the light source 123 as viewed from the D1 direction to the shape of the modulation surface of the light modulation element 183 as one progresses from the +D1 side to the -D1 side.

[0117] A side surface 143s of the light-guiding element 143 and a reflecting surface 143r provided on the side surface 143s as described below form a predetermined angle with respect to a virtual line VX perpendicular to the incident end 143a and the optical axis, and move away from the virtual line within a plane including the D2 and D3 directions as one moves from the -D2 side to the +D2 side. The red light LR incident on the light-guiding element 143 propagates from the +D1 side to the -D1 side through an internal space surrounded by the incident end 143a, the exit end 143b, and the reflecting surface 143r.

[0118] The shape of the modulation surface of the light modulator 183 when viewed along the D1 direction is rectangular, and the shape of the light source 123 when viewed along the D1 direction is rectangular. The predetermined angle α formed by the side surface 143s and the reflecting surface 143r, including the short side of the rectangular shape parallel to the D3 direction, with respect to the virtual line and the optical axis, is preferably, for example, within a range of 7° to 22°. The predetermined angle β formed by the side surface 143s and the reflecting surface 143r, including the long side of the rectangular shape parallel to the D2 direction, with respect to the virtual line and the optical axis, is preferably, for example, within a range of 14° to 36°. The preferable ranges of the angles α and β are appropriately set by a numerical simulation based on the configuration of the red light output unit 103 and ray tracing so that the reflective film 253 of the light guide element 143 has optical characteristics including desired polarization characteristics, as will be described later.

[0119] A portion of the red light LR incident on the light-guiding element 143 forms an angle with respect to the virtual line VX and the optical axis that is smaller than a predetermined angle, and does not enter the reflecting surface 143r even once, but propagates directly from the incident end 143a to the exit end 143b. The remaining portion of the red light LR incident on the light-guiding element 143 forms an angle with respect to the virtual line VX and the optical axis that is equal to or larger than a predetermined angle, and enters the reflecting surface 143r from the incident end 143a one or more times, is reflected by the reflecting surface 143r, and then reaches the exit end 143b. The path of the red light LR in the internal space SP143 varies depending on the angle of incidence on the incident end 143a, and follows multiple paths that are reflected by the reflecting surface 143r a different number of times.

[0120] The illuminance distribution of the red light LR propagating through the internal space SP143 toward the -D1 side is uniformed within a plane including the D2 and D3 directions. That is, the light-guiding element 143 uniforms the illuminance distribution of the incident red light LR within a plane including the D2 and D3 directions. The red light LR with its uniform illuminance distribution is emitted toward the -D1 side from the emission end 143b.

[0121] The light guide element 143 is a reflector, similar to the light guide elements 141 and 142, and is formed as a hollow member. When viewed along the D1 direction, the end on the +D1 side of the light guide element 143 has the same shape and size as the incident end 143a and the light emitting surface of the light source 123, and is formed, for example, in a rectangular shape. The end on the -D1 side of the light guide element 143 has the same shape and size as the exit end 143b and the modulation surface of the light modulation element 183, and is formed, for example, in a rectangular shape with a different size from the end on the +D1 side.

[0122] The reflector of the light guide element 143 is composed of four plate-like members 243 and a reflective film 253. The four plate-like members 243 correspond to a third base material. The reflective film 253 corresponds to a third reflective film. The reflector is formed by connecting the sides corresponding to the legs of the four trapezoidal plate-like members 243. The width, i.e., dimensions, of the sides parallel to the D2 or D3 direction on the +D1 side corresponding to the upper base of each of the four plate-like members 243 are set according to the size of the incident end 143a and the light-emitting surface of the light source 123 in the D2 or D3 direction. The width, i.e., dimensions, of the sides parallel to the D2 or D3 direction on the -D1 side corresponding to the lower base of each of the four plate-like members 243 are set according to the size of the exit end 143b and the modulation surface of the light modulation element 183 in the D2 or D3 direction.

[0123] Considering the size of the light source 123, the length of the plate-shaped member 243 in the D1 direction from the incident end 143a to the exit end 143b is 5 mm to 25 mm, and preferably 8 mm to 25 mm. If the length of the plate-shaped member 243 in the D1 direction is longer than 25 mm, the reflection loss of the red light LR in the light-guiding element 143 may increase excessively.

[0124] Of the four plate-shaped members 243, a side portion corresponding to a leg on one side of a first plate-shaped member 243 is connected to a side portion corresponding to a leg on one side of a second plate-shaped member 243. A side portion corresponding to a leg on the other side of the second plate-shaped member 243 is connected to a side portion corresponding to a leg on one side of a third plate-shaped member 243. A side portion corresponding to a leg on the other side of the third plate-shaped member 243 is connected to a side portion corresponding to a leg on one side of a fourth plate-shaped member 243. A side portion corresponding to a leg on the other side of the fourth plate-shaped member 243 is connected to a side portion corresponding to a leg on the other side of the first plate-shaped member 243.

[0125] The material of the plate-shaped member 243 does not exhibit polarization properties for the red light LR. The material of the plate-shaped member 242 includes, for example, Al, Ag, or glass, and is the same as the material of the plate-shaped members 241 and 242, for example.

[0126] When the plate-shaped member 243 is made of Al or Ag, the plate-shaped member 243 increases the heat dissipation property of the light guide element 143 and increases the reflectance of the red light LR that propagates in the internal space SP143 and transmits through the reflective film 253. When the plate-shaped member 243 is made of glass, the plate-shaped member 243 increases the heat resistance of the light guide element 143, reduces the weight of the light guide element 143, and facilitates processing of the light guide element 143. In this embodiment, it is assumed that the plate-shaped member 243 is made of glass that is translucent to the red light LR.

[0127] In the reflector of the light guide element 143, in order to increase the reflectance of the red light LR incident from the incident end 143a into the light guide element 143 near the side surface 143s, a reflective film 253 made of a dielectric multilayer film or the like is provided on the plate surface of a plate-like member 243 constituting the reflector opposite to the side surface 143s, i.e., on the plate surface 243p facing the internal space SP143 of the light guide element 143. Of the red light LR incident from the incident end 143a into the internal space SP143 of the light guide element 143, S-polarized red light LRS is reflected by the reflective film 253 and travels toward the -D1 side. The red light LRS corresponds to the first polarization component of the third light.

[0128] The intensity of the red light LRS reflected by the reflective film 253 and emitted from the reflective film 253 depends on the angle of incidence of the red light LR incident on the reflective film 253, etc. When the reflective film 253 is configured as a dichroic film, the incidence angle dependency of the intensity of the red light LRS emitted from the reflective film 253 changes depending on parameters such as the thickness of each of the low refractive index layers and high refractive index layers that constitute the dielectric multilayer film of the dichroic film, the number of each of the low refractive index layers and high refractive index layers, the refractive index of each of the low refractive index layers and high refractive index layers, and the refractive index difference between the low refractive index layers and the high refractive index layers.

[0129] As described above, for example, when the angle α is within the range of 7° or more and 22° or less and the angle β is within the range of 14° or more and 36° or less, the reflective film 253 is designed and the parameters of the reflective film 253 are appropriately determined so that the incident angle of the red light LR at which the intensity of the red light LRS emitted from the reflective surface 143r and the reflective film 253 is the highest is within the range of 60° to 90°.

[0130] The reflective film 253 is, for example, a dichroic film. The dichroic film forming the reflective film 253 is composed of low-refractive index layers and high-refractive index layers alternately stacked along a direction perpendicular to the plate surface 243p of the plate-shaped member 243. The low-refractive index layers and high-refractive index layers have different refractive indices for the red light LR. The high-refractive index layers are made of, for example, TiO2 or Ta2O5. The low-refractive index layers are made of, for example, SiO2.

[0131] The light-guiding element 143 reflects the red light LR emitted from the light-emitting surface of the light source 123 within a range of large angles relative to the optical axis, i.e., the red light LRS of the red light LR emitted at a wide angle, by the reflective film 253 and propagates the red light LRS in the internal space SP143, thereby adjusting and collecting the beam area of ​​the red light LRS to the size of the emission end 143b.

[0132] The incident angle θ of the red light LR emitted from the light source 123 and incident on the plate surface 243p of the plate-shaped member 243 and the reflective film 253 in increases in the D1 direction from the entrance end 143a to the exit end 143b, that is, from the +D1 side to the −D1 side.

[0133] The dichroic film forming the reflective film 253 reflects at least the red light LRS of the red light LR emitted from the light source 123 and incident from the internal space SP143 of the light-guiding element 143, and reflects the red light LRS most strongly. The red light LRS reflected by the reflective film 253 reaches the exit end 143b directly, or reaches the exit end 143b after being further reflected by the reflective film 253 on the -D1 side. The reflective film 253 transmits P-polarized red light LRP of the red light LR incident from the internal space SP143. The red light LRP transmitted through the reflective film 253 is transmitted through the plate-shaped member 243, refracted, and emitted to the outside of the light-guiding element 143 in a plane including the D2 direction and the D3 direction. The red light LRP corresponds to the second polarization component of the third light.

[0134] In the red light output unit 103 of this embodiment, the reflectance of the reflective film 253 for the red light LRS is different from the reflectance of the reflective film 253 for the red light LRP and is higher than the reflectance of the reflective film 253 for the red light LRP. As a result, as described above, the S-polarized red light LRS of the red light LR incident on the light-guiding element 143 from the incident end 143a is most strongly output from the output end 143b.

[0135] When the transmittance of the reflective film 253 and the plate-shaped member 243 for the red light LRP is higher than the absorptance, the red light LRP absorbed by the reflective film 253 and the plate-shaped member 243 is reduced, and heat is less likely to accumulate in the light-guiding element 143. This prevents the light-guiding element 143 from being deformed or distorted due to heat, and suppresses deterioration of the light-guiding element 143 over time.

[0136] Incident angle θ of the reflective film 253 in The reflectance and transmittance for each of the red light LRS and LRP incident at the end 143b are adjusted by parameters such as the thickness of each of the low refractive index layers and high refractive index layers of the dielectric multilayer film that constitutes the dichroic film, the number of each of the low refractive index layers and high refractive index layers, the refractive index of each of the low refractive index layers and high refractive index layers, and the refractive index difference between the low refractive index layers and the high refractive index layers, and are appropriately set so that the red light LRS is guided to the exit end 143b with high efficiency.

[0137] The incident angle θ of the red light LR on the reflecting surface 143r and the reflecting film 253 in and the intensity of the red light LR emitted from the reflecting surface 143r and the reflecting film 253 can be obtained by a numerical simulation based on the configuration and ray tracing of the red light emitting unit 103. The parameters of the dielectric multilayer film constituting the dichroic film of the reflecting film 253 are set as the incident angle θ of the red light LR from the internal space SP143. in For example, as mentioned above, the incident angle θ of the red light LR that is most incident on the -D1 side is in is the incident angle θ of the red light LR that is most incident on the +D1 side in Therefore, in the light-guiding element 143, the film thickness of the reflective film 253 on the side of the exit end 143b, i.e., the -D1 side, of the center position PTC in the direction along the optical axis of the red light LR, is greater than the film thickness of the reflective film 253 on the side of the entrance end 143a, i.e., the +D1 side, of the position PTC in the D1 direction.

[0138] As described above, the reflectance, transmittance, and absorptance of the light-guiding element 143 for the red light LR, and the dielectric multilayer film of the dichroic film that forms the reflective film 253 are set, so the amount of red light LRP emitted from the emission end 143b of the light-guiding element 143 is less than the amount of red light LRS emitted from the emission end 143b of the light-guiding element 143.

[0139] The collimating element 163 is provided on the optical path of the red light LRS emitted from the light guide element 143, and is disposed on the -D1 side of the light guide element 143 and at a position overlapping with the light guide element 143 in the D2 and D3 directions. The collimating element 163 collimates the red light LRS emitted from the light guide element 143 along the D1 direction.

[0140] The collimating element 163 is, for example, a plano-convex lens, and has an incident surface formed of a flat surface perpendicular to the D1 direction and an exit surface formed of a convex curved surface protruding toward the exit side of the red light LRS. The focal point of the plano-convex lens constituting the collimating element 163 is at least on the +D1 side of the collimating element 163, is opposite to the -D1 side from which the red light LR is exited from the collimating element 163, and is further on the +D1 side of the light-guiding element 143. The incident surface of the collimating element 163 is in contact with the exit end 143b of the light-guiding element 143. By having the collimating element 163 in contact with the exit end 143b, the red light LRS exited from the exit end 143b of the light-guiding element 143 is taken in by the collimating element 163 to the maximum extent, thereby suppressing loss of the red light LRS. However, the collimating element 163 may be an optical lens other than a plano-convex lens that can collimate the incident red light LRS, and may be disposed at an appropriate distance from the light guide element 143 in the D1 direction.

[0141] The incident-side polarizing element 173 is provided on the optical path of the red light LRS emitted from the collimating element 163, and is disposed on the -D1 side of the collimating element 163 and at a position overlapping with the collimating element 163 in the D2 and D3 directions. The incident-side polarizing element 173 is in contact with the light modulation element 183 from the +D1 side, for example, but may be disposed at an appropriate distance from the light modulation element 183 in the D1 direction. The incident-side polarizing element 173 emits a predetermined polarized light of the red light LRS emitted from the collimating element 163 toward the -D1 side along the D1 direction. The predetermined polarized light is, for example, S-polarized light.

[0142] The incident-side polarizing element 173 is, for example, a reflective polarizing plate or an absorptive polarizing plate having a plate surface parallel to a plane including the D2 and D3 directions. The incident-side polarizing element 173 transmits a portion of the incident red light LR containing a predetermined polarization to the -D1 side, and reflects or absorbs the other portion of the red light LR to the +D1 side. Note that, if it is desired to suppress return light and stray light to the light source 123, it is desirable that the incident-side polarizing element 173 be an absorptive polarizing plate.

[0143] In the red light LR emitted from the exit end 143b of the light-guiding element 143, the amount of P-polarized red light LRP is significantly reduced compared to the amount of S-polarized red light LRS. Therefore, the less change or disturbance in polarization of the red light LR in the D1 direction after it is emitted from the exit end 143b of the light-guiding element 143 and passes through the collimating element 163 before it is incident on the incident surface of the incident-side polarizing element 173, the more the amount of red light LRP reflected to the +D1 side by the incident-side polarizing element 173 or absorbed by the incident-side polarizing element 173 is reduced as much as possible. This reduces the load on the incident-side polarizing element 173 and suppresses thermal degradation of the incident-side polarizing element 173.

[0144] The light modulation element 183 is provided on the optical path of the red light LR emitted from the incident-side polarizing element 173, and is disposed on the -D1 side of the incident-side polarizing element 173 and at a position overlapping with the incident-side polarizing element 173 in the D2 and D3 directions. The light modulation element 183 corresponds to a third light modulation element, and modulates the red light LRS of the red light LR based on image information transmitted from an external image forming device such as a computer (not shown) connected to the light modulation element 183. The red light LRP of the red light LR does not significantly contribute to the predetermined color balance of the image projected by the projector 301.

[0145] The light modulation element 183 is, for example, a transmissive liquid crystal panel. The liquid crystal panel constituting the light modulation element 183 has a plurality of pixels (not shown). Each pixel is equipped with a switching element. The switching element is, for example, a TFT. An electrical signal corresponding to the brightness of red light at the relative position of each pixel on the modulation surface of the light modulation element 183 in the image projected by the projector 301 is supplied to the switching element of each pixel. Each pixel modulates the vibration direction of the red light LRS incident from the incident-side polarizing element 173 by the operation of the switching element in response to the electrical signal, thereby generating red image light IR. The image light IR corresponds to the light emitted from the third light modulation element. The light modulation element 183 emits the image light IR generated by the liquid crystal panel toward the -D1 side along the D1 direction.

[0146] 1, the exit-side polarizing element 177 is provided on the optical path of the image light IR exiting from the light modulation element 183, and is disposed on the -D1 side of the light modulation element 183 and at a position overlapping with the light modulation element 183 in the D2 and D3 directions. The exit-side polarizing element 177 is in contact with the light modulation element 183 from the -D1 side, for example, but may be disposed at an appropriate distance from the light modulation element 183 in the D1 direction. The exit-side polarizing element 177 exits predetermined polarized light of the image light IR exiting from the light modulation element 183 toward the -D1 side along the D1 direction. The predetermined polarized light is, for example, P-polarized light.

[0147] The exit-side polarizing element 177 is, for example, a reflective polarizing plate or an absorptive polarizing plate having a plate surface parallel to a plane including the D2 direction and the D3 direction. The exit-side polarizing element 177 transmits a portion of the incident image light IR containing a predetermined polarization to the +D2 side, and reflects or absorbs the other portion of the green light LG to the -D2 side. Note that, if it is desired to suppress return light and stray light to the light modulation element 183, it is desirable that the exit-side polarizing element 177 be an absorptive polarizing plate.

[0148] Light combining element 200 is disposed in a region where the optical path of red image light IR emitted from emission-side polarizing element 175, the optical path of green image light IG emitted from emission-side polarizing element 176, and the optical path of red image light IR emitted from emission-side polarizing element 177 intersect. Light combining element 200 combines image light IB, IG, and IR emitted from emission-side polarizing elements 175, 176, and 177, and emits the combined light to the +D2 side along the D2 direction.

[0149] The light combining element 200 is, for example, a cross dichroic prism 210. The cross dichroic prism 210 has an incident surface 210c facing the exit surface of the exit-side polarizing element 175, an incident surface 210d facing the exit surface of the exit-side polarizing element 176, an incident surface 210e facing the exit surface of the exit-side polarizing element 177, an exit surface 210b, and two reflective films 211 and 212. The incident surfaces 210c and 210e are parallel to a plane including the D2 and D3 directions and overlap each other in the D2 and D3 directions. The incident surface 210d and the exit surface 210b are parallel to a plane including the D1 and D3 directions and overlap each other in the D1 and D3 directions.

[0150] The reflective film 211 is arranged such that, when viewed along the D3 direction, the reflective film 211 changes from +D2 side to -D2 side as it moves from -D1 side to +D1 side. The reflective film 212 is arranged such that, when viewed along the D3 direction, the reflective film 212 changes from -D2 side to +D2 side as it moves from -D1 side to +D1 side. The reflective films 211 and 212 overlap with the incident surfaces 210c and 210e in the D2 direction, and overlap with the exit surface 210b and the incident surface 210d in the D3 direction. The reflective film 211 reflects light in the blue wavelength band and transmits light in the green and red wavelength bands. The reflective film 212 reflects light in the red wavelength band and transmits light in the blue and green wavelength bands.

[0151] When viewed from the D3 direction, the cross dichroic prism 210 is configured by four right-angle prisms bonded together at their right-angle surfaces, with their right-angle vertices aligned at the center of the light combining element 200. The four right-angle prisms of the cross dichroic prism 210 are formed of a transparent material that transmits light in the visible wavelength range. The reflective film 211 is disposed on one of the right-angle surfaces of the four right-angle prisms, which moves from the +D2 side to the -D2 side as one moves from the -D1 side to the +D1 side, as described above, and is formed of, for example, a dielectric multilayer film. The reflective film 212 is disposed on one of the right-angle surfaces of the four right-angle prisms, which moves from the -D2 side to the +D2 side as one moves from the -D1 side to the +D1 side, as described above.

[0152] The P-polarized light of blue image light IB emitted from the emission-side polarizing element 175 enters the inside of the cross dichroic prism 210 from the entrance surface 210c toward the +D1 side along the D1 direction, passes through the reflective film 211, is reflected by the reflective film 212, and travels toward the +D2 side. The P-polarized light of green image light IG emitted from the emission-side polarizing element 176 enters the inside of the cross dichroic prism 210 from the entrance surface 210d toward the +D2 side along the D2 direction, passes through the reflective films 211 and 212, and travels straight toward the +D2 side.

[0153] The P-polarized red image light IR emitted from the emission-side polarizing element 177 enters the inside of the cross dichroic prism 210 from the entrance surface 210e toward the -D1 side along the D1 direction, passes through the reflective film 212, is reflected by the reflective film 211, and travels toward the +D2 side. The image light IB, IG, and IR emitted toward the +D2 side from the reflective films 211 and 212 of the cross dichroic prism 210 are combined with each other to generate full-color image light IM. The cross dichroic prism 210 emits the full-color image light IM from the exit surface 210b toward the +D2 side along the D2 direction.

[0154] The projection optical system 250 is disposed on the optical path of the image light IM emitted from the light combining element 200. The projection optical system 250 projects the image light IM emitted from the projection optical system 250 onto a screen SCR disposed on the +D2 side, and enlarges and displays the image transmitted from the image forming device to the light modulation elements 181, 182, and 183 on the screen SCR.

[0155] The projection optical system 250 is configured, for example, by one or more optical lenses arranged along the direction D2. The optical lenses include, for example, a plano-convex lens, a plano-concave lens, a biconvex lens, a biconcave lens, a meniscus lens, an aspherical lens, a free-form lens, and the like.

[0156] The projector 301 of the present embodiment described above includes a light source (first light source) 121, a light guide element (first light guide element) 141, a light modulation element (first light modulation element) 181, and a projection optical system 250. The light source 121 emits blue light (first light) LB in a blue wavelength band (first wavelength band). The light guide element 141 has an incident end (first incident end) 141a into which the blue light LB emitted from the light source 121 is incident, and an exit end (first exit end) 141b from which the blue light LB is emitted. The light modulation element 181 modulates S-polarized blue light (first polarization component) LBS of the blue light LB emitted from the light guide element 141 based on image information. The projection optical system 250 projects image light (light) IM emitted from the light modulation element 181. The light guide element 141 has a plate-like member (first base material) 241 and a reflective film (first reflective film) 251. The reflective film 251 is disposed on a plate surface (first surface) 241p that forms the surface (inner surface) of the plate-like member 241 that faces the internal space SP141 of the light guide element 141. In the projector 301 of this embodiment, the reflective film 251 reflects the incident blue light LBS and transmits P-polarized blue light (second polarization component) LBP of the blue light LB. The blue light LBS reflected by the reflective film 251 is emitted from the emission end 141b of the light guide element 141 to the -D1 side.

[0157] In projector 301 of the present embodiment, P-polarized blue light LBP in the blue wavelength band, which is not subject to modulation into image light IB by light modulation element 181 and is unnecessary for forming a projected image, is not reflected by reflective film 251 of light guide element 141, hardly propagates toward the -D1 side in internal space SP141, and is not emitted from exit end 141b toward incident-side polarizing element 171 and light modulation element 181. According to projector 301 of the present embodiment, it is possible to reduce the thermal load on optical elements and components, including incident-side polarizing element 171 and light modulation element 181, that are arranged downstream of light guide element 141 on the optical paths of blue light LB and image light IB.

[0158] The projector 301 of this embodiment further includes a light source (second light source) 122, a light source (third light source) 123, a light guide element (second light guide element) 142, a light guide element (third light guide element) 143, a light modulation element (second light modulation element) 182, a light modulation element (third light modulation element) 183, and a light combining element 200. The light source 122 emits green light (second light) LG in a green wavelength band (second wavelength band). The light source 123 emits red light (third light) LR in a red wavelength band (third wavelength band). The light guide element 142 has an incident end (second incident end) 142a into which the green light LG emitted from the light source 122 is incident, and an exit end (second exit end) 142b from which the green light LG is emitted. The light guide element 143 has an incident end (third incident end) 143a into which the red light LR emitted from the light source 123 enters, and an exit end (third exit end) 143b from which the red light LR exits. The light modulation element 182 modulates S-polarized green light (second light) LGS of the green light LG emitted from the light guide element 142 based on image information. The light modulation element 183 modulates S-polarized red light (third light) LRS of the red light LR emitted from the light guide element 143 based on image information. The light combining element 200 combines the image light (light) IB emitted from the light modulation element 181, the image light (light) IG emitted from the light modulation element 182, and the image light (light) IR emitted from the light modulation element 183.

[0159] In projector 301 of the present embodiment, P-polarized green light LGP in the green wavelength band and blue light LB3 in the blue wavelength band, which are not subject to modulation into image light IG by light modulation element 182 and are unnecessary for forming the projected image, are not reflected by reflective film 252 of light guide element 142, hardly propagate toward the +D2 side in internal space SP142, and are not emitted from exit end 142b toward incident-side polarizing element 172 and light modulation element 182. Projector 301 of the present embodiment can reduce the thermal load on optical elements and components, including incident-side polarizing element 171 and light modulation element 181, that are arranged downstream of light guide element 142 on the optical paths of green light LG and image light IG. Furthermore, in the projector 301 of this embodiment, P-polarized red light LRP in the red wavelength band, which is not subject to modulation into image light IR by the light modulation element 183 and is unnecessary for forming a projected image, is not reflected by the reflective film 253 of the light guide element 143, hardly propagates toward the -D1 side in the internal space SP143, and is not emitted from the exit end 143b toward the incident-side polarizing element 173 and the light modulation element 183. The projector 301 of this embodiment can reduce the thermal load on optical elements and components, including the incident-side polarizing element 172 and the light modulation element 182, that are arranged downstream of the light guide element 143 on the optical paths of the red light LR and the image light IR. The projector 301 of this embodiment can facilitate the design of reflective films that reduce unnecessary colored light emitted downstream of the light guide element on different optical paths for the three colored lights of blue light, green light, and red light.

[0160] In the projector 301 of this embodiment, the cross-sectional shapes of the light guide elements 141 and 143 perpendicular to the optical axis and the D1 direction are rectangular, and the cross-sectional shape of the light guide element 142 perpendicular to the optical axis and the D2 direction is rectangular.

[0161] The projector 301 of this embodiment can easily generate rectangular blue light LBS, green light LGS, and red light LRS with uniform illuminance in a plane perpendicular to the optical axis of the colored light by the light guide elements 141, 142, and 143. The projector 301 of this embodiment can easily generate rectangular colored light that matches the modulation surfaces of the light modulation elements 181, 182, and 183.

[0162] In the projector 301 of this embodiment, the reflective film 251 of the light guide element 141 is a dichroic film. The dichroic film forming the reflective film 251 reflects blue light LB1 in a first blue wavelength band (light in a fourth wavelength band) included in the blue wavelength band of the blue light LB emitted from the light source 121, and as a result, reflects blue light LBS1. The dichroic film forming the reflective film 251 transmits blue light LB2 in a second blue wavelength band.

[0163] In the projector 301 of this embodiment, blue light LB2 in the second blue wavelength band, which is not subject to modulation into image light IB by the light modulation element 181 and is unnecessary for forming a projected image, is not reflected by the reflective film 251 of the light guide element 141, hardly propagates toward the -D1 side in the internal space SP141, and is not emitted from the exit end 141b toward the incident-side polarizing element 171 and the light modulation element 181. According to the projector 301 of this embodiment, it is possible to further reduce the thermal load on optical elements and components arranged downstream of the light guide element 141 on the optical paths of the blue light LB and the image light IB, thereby improving the color reproducibility of the projected image. In particular, because the blue light LB2 in the second blue wavelength band, which is close to the ultraviolet wavelength band within the visible wavelength band and which can be irradiated onto the incident-side polarizing element 171 and the light modulation element 181, is minimized, deterioration of the incident-side polarizing element 171 and the light modulation element 181 is suppressed.

[0164] In the projector 301 of this embodiment, the reflective film 252 of the light guide element 142 is a dichroic film. The dichroic film forming the reflective film 252 reflects the green light LG of the green light LG and the blue light LB3 emitted from the light source 122, and as a result, reflects the green light LGS. The dichroic film forming the reflective film 252 transmits the blue light LB3 in the third blue wavelength band.

[0165] In the projector 301 of the present embodiment, blue light LB3 in the third blue wavelength band, which is not subject to modulation into image light IG by the light modulation element 183 and is unnecessary for forming the projected image, is not reflected by the reflective film 252 of the light guide element 142, hardly propagates toward the +D2 side in the internal space SP142, and is not emitted from the emission end 142b toward the incident-side polarizing element 172 and the light modulation element 182. According to the projector 301 of the present embodiment, it is possible to further reduce the thermal load on optical elements and components that are arranged downstream of the light guide element 142 on the optical paths of the blue light LB3 and the image light IG, and it is possible to further improve the color reproducibility of the projected image.

[0166] In the projector 301 of this embodiment, the cross-sectional area including the D2 and D3 directions of the exit end 141b of the light guide element 141 is larger than the cross-sectional area including the same directions of the incident end 141a of the light guide element 141. The cross-sectional area including the D1 and D3 directions of the exit end 142b of the light guide element 142 is larger than the cross-sectional area including the same directions of the incident end 142a of the light guide element 142. The cross-sectional area including the D2 and D3 directions of the exit end 143b of the light guide element 143 is larger than the cross-sectional area including the same directions of the incident end 143a of the light guide element 143.

[0167] In the projector 301 of this embodiment, the illuminance distributions of the blue light LBS, green light LGS, and red light LRS are uniformized and the irradiation area of ​​each color light is expanded from the time when they enter the light guide elements 141 a, 142 a, and 143 a through the incident ends 141 b, 142 b, and 143 b and exit through the exit ends 141 b, 142 b, and 143 b. According to the projector 301 of this embodiment, the illuminance distributions of the blue light LB, green light LG, and red light LR emitted from the light sources 121, 122, and 123 can be uniformized in a plane perpendicular to the optical axis, and the sizes of the blue light LBS, green light LGS, and red light LRS in the plane perpendicular to the optical axis, i.e., the irradiation areas, can be easily expanded to match the modulation surfaces of the light modulation elements 181, 182, and 183.

[0168] In the projector 301 of this embodiment, the film thickness of the reflective film 251 on the side of the incident end 141a from the position (center) PTC in the direction D1 along the optical axis of the blue light LB of the light-guiding element 141 is smaller than the film thickness of the reflective film 251 on the side of the exit end 141b from the position PTC.

[0169] According to the projector 301 of this embodiment, the incident angle θ of the blue light LB with respect to the reflective film 251 on the +D1 side of the position PTC from the internal space SP141 of the light guide element 141 is in is the incident angle θ of the blue light LB to the reflective film 251 on the −D1 side of the position PTC. in Even if the reflectance is larger than 1 / 2, the optical characteristics including the reflection characteristics of the reflective film 251 in the D1 direction can be made uniform.

[0170] Specifically, in the direction D1 along the optical axis of the blue light LB of the light guide element 141, the incident angle θ in is the incident angle θ of the blue light LB incident on the reflective film 251 on the incident end 141a side. in is greater than.

[0171] According to the projector 301 of this embodiment, the incident angle θ of the blue light LB from the internal space SP141 of the light guide element 141 to the reflective film 251 is in Even if changes along the D1 direction and increases from the −D1 side to the +D1 side, the optical characteristics of the reflective film 251 in the D1 direction can be made uniform.

[0172] Similarly, the film thickness of the reflective film 252 on the incident end 142a side of the position (center) PTC in the direction D2 along the optical axis of the green light LG of the light-guiding element 142 is smaller than the film thickness of the reflective film 252 on the exit end 142b side of the position PTC. The film thickness of the reflective film 253 on the incident end 143a side of the position (center) PTC in the direction D1 along the optical axis of the red light LR of the light-guiding element 143 is smaller than the film thickness of the reflective film 253 on the exit end 143b side of the position PTC.

[0173] According to the projector 301 of this embodiment, the incident angle θ of the green light LG with respect to the reflective film 252 on the +D2 side of the position PTC from the internal space SP142 of the light guide element 142 is in is the incident angle θ of the green light LG to the reflective film 252 on the −D2 side of the position PTC. in Even if the incident angle θ of the green light LG to the reflective film 253 on the −D1 side of the position PTC from the internal space SP143 of the light guide element 143 is larger than θ, the optical characteristics including the reflection characteristics in the D2 direction of the reflective film 252 can be made uniform. in is the incident angle θ of the red light LR to the reflective film 253 on the +D1 side of the position PTC. in Even if the reflectance is larger than 1 / 2, the optical characteristics including the reflection characteristics of the reflective film 253 in the D1 direction can be made uniform.

[0174] Specifically, in the direction D2 along the optical axis of the green light LG of the light guide element 142, the incident angle θ in is the angle of incidence θ of the green light LG incident on the reflective film 252 on the incident end 142a side. in In the direction D1 along the optical axis of the red light LR of the light guide element 143, the incident angle θ of the red light LR incident on the reflective film 253 on the side of the exit end 143b is larger than in is the incident angle θ of the red light LR incident on the reflective film 253 on the incident end 143a side. in is greater than.

[0175] According to the projector 301 of this embodiment, the incident angle θ of the green light LG from the internal space SP142 of the light guide element 142 to the reflective film 252 in Even if the incident angle θ of the red light LR from the internal space SP143 of the light guide element 143 to the reflective film 253 changes and increases along the D2 direction, the optical characteristics of the reflective film 252 can be made uniform in the D2 direction. in Even if the optical characteristic of the reflective film 253 changes and increases along the D1 direction, it is possible to make the optical characteristic of the reflective film 253 uniform in the D1 direction.

[0176] The projector 301 of this embodiment further includes an incident-side polarizing element (incident-side polarizing plate) 171 between the light guide element 141 and the light modulation element 181. In addition, an incident-side polarizing element (incident-side polarizing plate) 172 is further included between the light guide element 142 and the light modulation element 182. An incident-side polarizing element (incident-side polarizing plate) 173 is further included between the light guide element 143 and the light modulation element 183.

[0177] According to projector 301 of this embodiment, the light guide element 141 can reduce the amount of blue light LBP emitted from the emission end 141b, thereby reducing the thermal load on the incident-side polarizing element 171 and increasing the contrast of blue in the projected image. Similarly, the light guide element 142 can reduce the amount of green light LGP emitted from the emission end 142b, thereby reducing the thermal load on the incident-side polarizing element 172 and increasing the contrast of green in the projected image. Furthermore, the light guide element 143 can reduce the amount of red light LRP emitted from the emission end 143b, thereby reducing the thermal load on the incident-side polarizing element 173 and increasing the contrast of red in the projected image.

[0178] In the projector 301 of this embodiment, the plate-like members 241, 242, and 243 of the light guide elements 141, 142, and 143 are made of glass.

[0179] According to the projector 301 of this embodiment, it is possible to improve the heat resistance of the light guide elements 141, 142, and 143. Furthermore, according to the projector 301 of this embodiment, it is possible to reduce the weight of the light guide elements 141, 142, and 143, and it is also possible to easily manufacture the light guide elements 141, 142, and 143.

[0180] Furthermore, in the projector 301 of this embodiment, glass, which can easily ensure surface precision, is used as the material for the plate-like members 241, 242, and 243, and reflective films 251, 252, and 253 are formed on the plate surfaces 241p, 242p, and 243p of the glass plate-like members 241, 242, and 243, which have high surface precision. According to the projector 301 of this embodiment, it is possible to adjust the optical characteristics of the light guide element 141 with respect to the blue light LBS with high precision and reduce the weight of the light guide element 141. It is possible to adjust the optical characteristics of the light guide element 142 with respect to the green light LGS with high precision and reduce the weight of the light guide element 142. It is possible to adjust the optical characteristics of the light guide element 143 with respect to the red light LRS with high precision and reduce the weight of the light guide element 143.

[0181] In the projector 301 of this embodiment, the distance in the D1 direction from the incident end 141a to the exit end 141b of the light guide element 141 is 8 mm or more and 25 mm or less. The distance in the D2 direction from the incident end 142a to the exit end 142b of the light guide element 142 is 8 mm or more and 25 mm or less. The distance in the D1 direction from the incident end 143a to the exit end 143b of the light guide element 143 is 8 mm or more and 25 mm or less.

[0182] In the projector 301 of this embodiment, the lengths of the light-guiding elements 141, 142, and 143 in the direction along the optical axis of the colored light are appropriately set, so that the illuminance distribution in the plane perpendicular to the optical axis of each of the blue light LB, green light LG, and red light LR guided by the light-guiding elements 141, 142, and 143 can be efficiently uniformed, and the blue light LB, green light LG, and red light LR can be expanded.

[0183] [First Modification] In the projector 301 of this embodiment, it is assumed that the plate-shaped members 241, 242, and 243 are made of glass as described above, but the plate-shaped members 241, 242, and 243 may be made of a metal such as Al or Ag. According to the projector having the configuration of this first modified example, it is possible to improve the heat dissipation properties of the light guide elements 141, 142, and 143 and the plate-shaped members 241, 242, and 243, and to easily increase the reflectance for color light in the visible wavelength band including blue light LB1, green light LG, and red light LR1.

[0184] In the projector according to the first modification of this embodiment, the plate-like members 241, 242, and 243 of the light guide elements 141, 142, and 143 are made of metal. According to the projector according to the first modification of this embodiment, the thermal conductivity of the plate-like members 241, 242, and 243 is increased, and even if the blue light LBP is not absorbed by the reflective film 251, the green light LGP is not absorbed by the reflective film 252, and the red light LRP is not absorbed by the reflective film 253, the plate-like members 241, 242, and 243 can efficiently exhaust or dissipate heat. This prevents deformation and distortion of the light guide elements 141, 142, and 143, and suppresses deterioration of the light guide elements 141, 142, and 143 over time.

[0185] [Second Modification] FIG. 6 is a cross-sectional view of the light guide element 141 of the blue light output unit 101 of a projector according to a second modified example of this embodiment, taken along a plane including the D1 and D2 directions. As shown in FIG. 6, the light guide element 141 further includes an absorption layer 271. The absorption layer 271 is provided on the plate surface 241q of the plate-shaped member 241. The absorption layer 271 absorbs the blue light LBP transmitted through the reflective film 251 and further absorbs the blue light LBS2. The absorption layer 271 is made of, for example, black paint, a polarizing filter capable of absorbing the blue light LBP, a polarizing film, or an anisotropic thin film. To ensure that the absorption layer 271 absorbs the blue light LBS2, it is preferable that the absorption layer 271 be made of black paint.

[0186] As described above, in the projector according to the second modification of this embodiment, the light guide element 141 has an absorption layer (first absorption layer) 271 arranged on the plate surface (second surface) 241q opposite the plate surface 241p of the plate-shaped member 241. The absorption layer 271 absorbs P-polarized blue light LBP of the blue light LB transmitted through the reflective film 251. According to the projector according to the second modification of this embodiment, propagation of the blue light LBP emitted outside the light guide element 141 in a plane including the D2 and D3 directions orthogonal to the optical axis of the blue light LB can be suppressed, thereby suppressing the generation of stray light. The projector according to the second modification of this embodiment can be made more compact than when an absorption member that absorbs blue light LBP is arranged separately from the light guide element 141.

[0187] Although not shown, in the projector according to the second modified example of this embodiment, in the green light output unit 102, similar to the blue light output unit 101, the light guide element 142 may include an absorption layer that absorbs the green light LGP that transmits through the reflective film 252. It is more preferable that this reflective film absorbs the blue light LB3. Furthermore, in the projector according to the second modified example of this embodiment, in the red light output unit 103, the light guide element 143 may include an absorption layer that absorbs the red light LRP that transmits through the reflective film 253. Like the absorption layer 271, the absorption layer is made of black paint, or a polarizing filter, polarizing film, anisotropic thin film, or the like that can absorb the green light LGP or the red light LRP.

[0188] According to the projector of the second modified example of this embodiment, it is possible to further suppress the generation of stray light by suppressing the propagation of the green light LGP and the red light LRP emitted to the outside of the light guide elements 142 and 143. Furthermore, the projector of the second modified example of this embodiment can be made smaller than when an absorbing member that absorbs the green light LGP and that is formed separately from the light guide element 142 and an absorbing member that absorbs the red light LRP and that is formed separately from the light guide element 143 are disposed.

[0189] [Third Modification] 7 is a cross-sectional view of the light guide element 141 of the blue light output unit 101 of the projector according to the third modified example of this embodiment, taken along a plane including the D1 and D2 directions. As shown in FIG. 7, the plate-like member 241 of the light guide element 141 absorbs the blue light LBP transmitted through the reflective film 251, and may also absorb the blue light LBS2.

[0190] As described above, in the projector of the third modified example of this embodiment, the plate-like member 241 absorbs the P-polarized blue light LBP that is transmitted through the reflective film 251. According to the projector of the third modified example of this embodiment, it is possible to suppress the propagation of the blue light LBP that is emitted outside the light guide element 141 in a plane that includes the D2 direction and the D3 direction that are orthogonal to the optical axis of the blue light LB, and therefore it is possible to suppress the generation of stray light. The projector of the third modified example of this embodiment can also be made smaller than when an absorption member that absorbs the blue light LBP is provided separately from the light guide element 141.

[0191] Although not shown, in the projector according to the third modification of this embodiment, in the green light output unit 102, the plate-like member 242 of the light guide element 142 may absorb the green light LGP transmitted through the reflective film 252, similar to the blue light output unit 101. Furthermore, in the projector according to the third modification of this embodiment, in the red light output unit 103, the plate-like member 243 of the light guide element 143 may absorb the red light LRP transmitted through the reflective film 253. According to the projector according to the third modification of this embodiment, the propagation of the green light LGP and the red light LRP output to the outside of the light guide elements 142 and 143 can be suppressed, thereby further reducing the occurrence of stray light. Furthermore, the projector according to the third modification of this embodiment can be made more compact than when an absorbing member that absorbs the green light LGP and that is formed separately from the light guide element 142 and an absorbing member that absorbs the red light LRP and that is formed separately from the light guide element 143 are provided.

[0192] [Fourth Modification] 8 is a cross-sectional view of the light guide element 141 of the blue light output unit 101 of the projector according to the third modified example of this embodiment, taken along a plane including the D1 and D2 directions. As shown in FIG. 8, the blue light output unit 101 of the projector according to the third modified example of this embodiment may include a light absorbing member 275.

[0193] The light absorbing member 275 is disposed on the optical path of the blue light LBP, LBS2 that passes through the reflective film 251 and the plate-shaped member 241 and is emitted to the outside of the light guide element 141 on a plane including the D2 direction and the D3 direction, and is disposed apart from the light guide element 141. The light absorbing member 275 is preferably a member that further absorbs the blue light LBS2 that passes through the reflective film 251 and the plate-shaped member 241. The light absorbing member 275 is a member configured separately from the light guide element 141, and is formed, for example, of a black member or a polarizing plate that absorbs at least the blue light LBP. The light absorbing member 275 absorbs the blue light LBP, LBS2 that passes through the reflective film 251 and the plate-shaped member 241 and is emitted to the outside of the light guide element 141.

[0194] As described above, the projector according to the fourth modification of this embodiment further includes the light absorbing member 275 that absorbs the blue light LBP that passes through the light guide element 141. The light absorbing member 275 is disposed away from the light guide element 141. According to the projector according to the fourth modification of this embodiment, it is possible to suppress the blue light LBP that is emitted outside the light guide element 141 from propagating over a wide area, thereby suppressing the occurrence of stray light. Furthermore, according to the projector according to the fourth modification of this embodiment, the amount of blue light LBP absorbed by the light guide element 141 is reduced, and the thermal load on the light guide element 141 can be reduced.

[0195] Although not shown, in the projector of the fourth modified example of this embodiment, similarly to the blue light output unit 101, in the green light output unit 102, a light absorbing member that absorbs the green light LGP may be arranged, away from the light guide element 142, on the optical path of the green light LGP that passes through the reflective film 252 of the light guide element 142 and the plate-shaped member 242. Also, in the projector of the fourth modified example of this embodiment, in the red light output unit 103, a light absorbing member that absorbs the red light LRP that passes through the reflective film 253 of the light guide element 143 and the plate-shaped member 243 may be arranged, away from the light guide element 143. According to the projector of the fourth modified example of this embodiment, it is possible to suppress propagation of the green light LGP and the red light LRP that are output to the outside of the light guide elements 142 and 143, and therefore it is possible to further suppress the occurrence of stray light. Furthermore, according to the projector of the fourth variant of this embodiment, the green light LGP absorbed by the light guide element 142 is reduced, and the red light LRP absorbed by the light guide element 143 is reduced, thereby reducing the thermal load on the light guide elements 142 and 143.

[0196] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims.

[0197] For example, in the blue light emitting unit 101 and the red light emitting unit 103, the LEDs constituting the light sources 121 and 123 may include a phosphor that is excited by light from the LED body and emits blue light LB and red light LR, similar to the green light emitting unit 102. Conversely, the LED of the light source 122 of the green light emitting unit 102 may not include the phosphor 124, and the light source 122 may be constituted by an LED that directly emits green light LG.

[0198] Furthermore, the projector of this embodiment may be a single-panel projector including: a first light source having an LED that emits white light; a first light guide element that uniforms the in-plane illuminance of the white light emitted from the light source; a first light modulation element that modulates the colored light emitted from the first light guide element based on image information; and a projection optical system that projects the image light emitted from the first light modulation element. According to the single-panel projector to which this embodiment is applied, even when the first light source emits blue light LB2 in a wavelength band close to the ultraviolet wavelength band, the first light guide element reduces the amount of blue light LBP that enters the first light modulation element, thereby suppressing deterioration of optical elements and components including the incident-side polarizing plate and the light modulation element, and improving the color reproducibility of the projected image.

[0199] Summary of this disclosure A summary of this disclosure is provided below. (Supplementary Note 1) A projector comprising: a first light source that emits first light of a first wavelength band; a first light guide element having a first entrance end into which the first light emitted from the first light source enters and a first exit end that emits the first light; a first light modulation element that modulates a first polarization component of the first light emitted from the first light guide element based on image information; and a projection optical system that projects the light emitted from the first light modulation element, wherein the first light guide element has a first base material and a first reflective film disposed on a first surface of the first base material that forms an inner surface of the first light guide element, the first reflective film reflecting the first polarization component and transmitting a second polarization component of the first light, the first polarization component reflected by the first reflective film being emitted from the first exit end.

[0200] The configuration of Appendix 1 reduces the second polarization component of the first light that is unnecessary for forming image light in the first light modulation element emitted from the first light-guiding element arranged in front of the first light modulation element, reduces the thermal load on the first light modulation element, suppresses deterioration of the first light modulation element, and improves the color reproducibility of the image projected by the projector.

[0201] (Supplementary Note 2) The projector of Supplementary Note 1 further includes: a second light source that emits second light in a second wavelength band; a third light source that emits third light in a third wavelength band; a second light guide element having a second incident end into which the second light emitted from the second light source is incident and a second exit end from which the second light is emitted; a third light guide element having a third incident end into which the third light emitted from the third light source is incident and a third exit end from which the third light is emitted; a second light modulation element that modulates the second light emitted from the second light guide element based on image information; a third light modulation element that modulates the third light emitted from the third light guide element based on image information; and a light combining element that combines the light emitted from the first light modulation element, the light emitted from the second light modulation element, and the light emitted from the third light modulation element.

[0202] In the configuration of Supplementary Note 2, the second polarization component of the second light that is unnecessary for forming image light in the second light modulation element and that is output from the second light guide element arranged in the preceding stage of the second light modulation element is reduced, and the second polarization component of the third light that is unnecessary for forming image light in the third light modulation element and that is output from the third light guide element arranged in the preceding stage of the third light modulation element is reduced. The configuration of Supplementary Note 2 reduces the thermal load on the second light modulation element and the third light modulation element, suppresses deterioration of the second light modulation element and the third light modulation element, and further improves the color reproducibility of the image projected by the projector.

[0203] (Supplementary Note 3) The projector according to Supplementary Note 1 or Supplementary Note 2, wherein the cross-sectional shape of the first light guide element is rectangular.

[0204] The configuration of Supplementary Note 3 makes it possible to easily generate a rectangular first light with a uniform illuminance distribution as illumination light.

[0205] (Appendix 4) The projector according to any one of appendices 1 to 3, wherein the first reflective film is a dichroic film, and the dichroic film reflects light in a fourth wavelength band included in the first wavelength band.

[0206] The configuration of Appendix 4 reduces the first light of wavelength bands other than the fourth wavelength band within the first wavelength band that is unnecessary for forming image light in the first light modulation element and is emitted from the first light-guiding element, thereby reducing the thermal load on the first light modulation element, suppressing deterioration of the first light modulation element, and further improving the color reproducibility of the image projected by the projector.

[0207] (Supplementary Note 5) The projector according to any one of Supplementary Notes 1 to 4, wherein a cross-sectional area of ​​the first exit end is larger than a cross-sectional area of ​​the first entrance end.

[0208] With the configuration of Supplementary Note 5, the size of the irradiation area of ​​the first light emitted from the first light source can be matched to the size of the modulation surface of the first light modulation element, and the illuminance distribution of the first light can be easily made uniform.

[0209] (Appendix 6) A projector according to Appendix 5, wherein the thickness of the first reflective film on the first incident end side of the first light guide element relative to the center in the direction along the optical axis of the first light is smaller than the thickness of the first reflective film on the first exit end side of the first light guide element relative to the center.

[0210] The configuration of Supplementary Note 6 makes it possible to make the reflection characteristics of the first reflection film uniform when the angle of incidence of the first light onto the first reflection film on the first entrance end side from the center in the direction along the optical axis of the first light in the first light-guiding element is smaller than the angle of incidence of the first light onto the first reflection film on the first exit side from the center.

[0211] (Appendix 7) A projector according to Appendix 6, wherein, in a direction along the optical axis of the first light of the first light guide element, an incident angle of the first light incident on the first reflective film on the first exit end side is larger than an incident angle of the first light incident on the first reflective film on the first entrance end side.

[0212] With the configuration of Supplementary Note 7, the thickness of the first reflective film increases from the first incident end to the first exit end in the direction along the optical axis of the first light in the first light guide element, and the reflection characteristics of the first reflective film can be made uniform.

[0213] (Supplementary Note 8) The projector according to any one of Supplementary Note 1 to Supplementary Note 7, further comprising an incident-side polarizing plate disposed between the first light guide element and the first light modulation element.

[0214] The configuration of Supplementary Note 8 can reduce the thermal load on the incident-side polarizing plate and increase the contrast of the projected image.

[0215] (Appendix 9) A projector according to any one of Appendices 1 to 8, wherein the first light guide element further has a first absorption layer, the first absorption layer being disposed on a second surface of the first substrate opposite the first surface, and absorbing the second polarization component that passes through the first reflection film.

[0216] The configuration of Supplementary Note 9 can suppress the generation of stray light and can also achieve a smaller size compared to a case where an absorption member formed separately from the light-guiding element and absorbing the second polarized component of the first light is disposed.

[0217] (Supplementary Note 10) The projector according to any one of Supplementary Note 1 to Supplementary Note 8, wherein the first base material absorbs the second polarized light component transmitted through the first reflective film.

[0218] The configuration of Supplementary Note 10 can suppress the generation of stray light and can also achieve a smaller size compared to a case where an absorption member formed separately from the light-guiding element is arranged to absorb the second polarization component of the first light.

[0219] (Appendix 11) The projector according to any one of appendices 1 to 8, further comprising a light absorbing member that absorbs the second polarized light component that passes through the first light guide element, the light absorbing member being positioned away from the first light guide element.

[0220] The configuration of Supplementary Note 11 can suppress the generation of stray light and reduce the thermal load on the light guide element.

[0221] (Appendix 12) The projector of Appendix 2, wherein the length from the first entrance end to the first exit end is 8 mm or more and 25 mm or less, the length from the second entrance end to the second exit end is 8 mm or more and 25 mm or less, and the length from the third entrance end to the third exit end is 8 mm or more and 25 mm or less.

[0222] The configuration of Appendix 12 makes it possible to efficiently uniformize the illuminance distribution of the first light emitted from the first light source, efficiently uniformize the illuminance distribution of the second light emitted from the second light source, efficiently uniformize the illuminance distribution of the third light emitted from the third light source, and expand the first light, second light, and third light toward the emission side. [Explanation of symbols]

[0223] 121...light source (first light source), 122...light source (second light source), 123...light source (third light source), 141...light guide element (first light guide element), 142...light guide element (second light guide element), 143...light guide element (third light guide element), 181...light modulation element (first light modulation element), 182...light modulation element (second light modulation element), 183...light modulation element (third light modulation element), 200...light combining element, 251...reflective film (first reflective film), 252...reflective film (second reflective film), 253...reflective film (third reflective film), 301...projector.

Claims

1. a first light source that emits first light in a first wavelength band; a first light guide element having a first incident end into which the first light emitted from the first light source is incident and a first emitting end from which the first light is emitted; a first light modulation element that modulates a first polarization component of the first light emitted from the first light guide element based on image information; a projection optical system that projects the light emitted from the first light modulation element; Equipped with The first light guide element is A first substrate; a first reflective film disposed on a first surface of the first substrate that forms an inner surface of the first light guide element; and the first reflective film reflects the first polarization component and transmits the second polarization component of the first light; the first polarized light component reflected by the first reflective film is emitted from the first exit end; projector.

2. a second light source that emits second light in a second wavelength band; a third light source that emits third light in a third wavelength band; a second light guide element having a second incident end into which the second light emitted from the second light source is incident and a second emitting end from which the second light is emitted; a third light guide element having a third incident end into which the third light emitted from the third light source is incident and a third exit end from which the third light is emitted; a second light modulation element that modulates the second light emitted from the second light guide element based on image information; a third light modulation element that modulates the third light emitted from the third light guide element based on image information; a light combining element that combines the light emitted from the first light modulation element, the light emitted from the second light modulation element, and the light emitted from the third light modulation element; Further provided with The projector according to claim 1 .

3. The cross-sectional shape of the first light guide element perpendicular to the optical axis of the first light is rectangular. The projector according to claim 1 or 2.

4. the first reflective film is a dichroic film, the dichroic film reflects light in a fourth wavelength band included in the first wavelength band; The projector according to claim 1 or 2.

5. The cross-sectional area of ​​the first exit end is larger than the cross-sectional area of ​​the first entrance end; The projector according to claim 1 or 2.

6. a thickness of the first reflective film on the first incident end side from a center of the first light guide element in a direction along the optical axis of the first light is smaller than a thickness of the first reflective film on the first exit end side from the center; The projector according to claim 5 .

7. an incident angle of the first light incident on the first reflective film on the first exit end side in a direction along the optical axis of the first light of the first light guide element is larger than an incident angle of the first light incident on the first reflective film on the first entrance end side; The projector according to claim 6 .

8. further comprising an incident-side polarizing plate disposed between the first light guide element and the first light modulation element; The projector according to claim 1 or 2.

9. the first light guide element further comprises a first absorption layer; the first absorption layer is disposed on a second surface of the first substrate opposite to the first surface, and absorbs the second polarized light component transmitted through the first reflection film; The projector according to claim 1 or 2.

10. the first substrate absorbs the second polarized light component transmitted through the first reflective film; The projector according to claim 1 or 2.

11. a light absorbing member that absorbs the second polarized light component that is transmitted through the first light guide element; The light absorbing member is disposed apart from the first light guide element. The projector according to claim 1 or 2.

12. The first substrate is made of metal or glass. The projector according to claim 1 or 2.

13. a length from the first incident end to the first exit end of the optical fiber is 8 mm or more and 25 mm or less; a length from the second entrance end to the second exit end that is equal to or greater than 8 mm and equal to or less than 25 mm; a length from the third input end to the third output end of the optical fiber is 8 mm or more and 25 mm or less; The projector according to claim 2 .

Images