Projector

Abstract

To suppress irradiation of a light modulation element with unnecessary light and enhance the color reproducibility of an image to be projected, in a projector.SOLUTION: A projector includes: a first light source that emits first light in a first wavelength band and second light in a second wavelength band; a first light guide element that has a first base material and a first reflective film which is arranged on the first base material, a first incident end on which the first light and the second light emitted from the first light source are incident, and a first emission end from which the first light is emitted; a first light modulation element that modulates the light in the first wavelength band 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 reflectance of the first light guide element with respect to the second light is lower than the reflectance with respect to the first light.SELECTED DRAWING: Figure 1

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. Projectors are classified into various types, such as single-panel and three-panel types, depending on the number of light sources and light modulation elements. For example, Patent Document 1 discloses a three-panel projector that includes light-emitting diodes (LEDs) that emit colored light, a block that emits the colored light from an exit end so that the brightness of the colored light incident from the LED is uniform, a condenser lens that forms an image of the light source of the colored light emitted from the block on the entrance pupil of a projection lens, a light modulation element that modulates the colored light into image light, and a projection lens. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-180962 Summary of the Invention [Problem to be solved by the invention]

[0004] In general, the wavelength band of color light emitted from an LED is wider than the wavelength band of laser light emitted from a laser diode (LD). The three-panel projector disclosed in Patent Document 1 uses an LED as the light source, so in addition to the color light necessary for image formation, color light in a wavelength band unnecessary for image formation may be incident on the light modulation element, which may affect the life of the light modulation element and reduce the color reproducibility of the projected image. [Means for solving the problem]

[0005] A projector according to one aspect of the present invention includes: a first light source that emits first light in a first wavelength band and second light in a second wavelength band; a first light guide element that has a first substrate and a first reflective film disposed on the first substrate, the first light guide element having a first incident end to which the first light and the second light emitted from the first light source are incident and a first exit end from which the first light is emitted; a first light modulation element that modulates the light in the first wavelength band 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 reflectance of the first light guide element for the second light is lower than the reflectance for the first light. [Brief explanation of the drawings]

[0006] [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] 3 is a side view of a light source and a light guide element of the blue light emitting unit of FIG. 2. [Figure 4] 2 is a schematic diagram of a green light emitting section of the projector in FIG. 1. [Figure 5] 2 is a side view of a green light output section and an incident-side polarizing element of the projector in FIG. 1. FIG. [Figure 6] FIG. 11 is a perspective view of a light guide element of a blue light emitting unit of a projector according to a second modified example of an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] 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.

[0008] 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.

[0009] 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.

[0010] 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.

[0011] The light source 121 is configured, for example, by an LED that emits blue light LB. The LED that emits blue light LB contains, for example, a gallium nitride (GaN)-based semiconductor material as a light emitter. The blue light LB in the blue wavelength band includes blue light LB1 in a first wavelength band and blue light LB2 in a second wavelength band. If the light source 121 is configured by an LED, the blue wavelength band is wider than if it is configured by an LD. The blue wavelength band is, for example, a wavelength band of 400 nm to 500 nm. The first wavelength band is, for example, 440 nm to 500 nm, and preferably includes 467 nm. The second wavelength band is a wavelength band different from the first wavelength band, for example, 400 nm to 440 nm. The second wavelength band is a wavelength band shorter than the first wavelength band and closer to the ultraviolet wavelength band than the first wavelength band. The blue light LB1 corresponds to the first light. The blue light LB2 corresponds to the second light.

[0012] In the blue light LB, the light intensity of blue light LB1 is approximately the same as that of blue light LB2. 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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. The size of the light emitting surface of the light source 121 in the D2 and D3 directions is, for example, 0.25 mm or more and 10 mm or less. The area of ​​the light emitting surface of the light source 121 when viewed along the D1 direction is, for example, 0.25 mm 2 ~10mm x 10mm 2 is.

[0017] The size of incident end 141a in the plane including the D2 and D3 directions may be equal to the size of the light-emitting surface of light source 121 in the plane including the D2 and D3 directions, but is preferably appropriately larger than the size of the light-emitting surface of light source 121 in the plane including the D2 and D3 directions. The dimension along the long side parallel to the D2 direction of opening API 141, through which blue light LB enters at incident end 141a, is, for example, not less than 1 mm and not more than 3 mm, and preferably about 2 mm.

[0018] The exit end 141b corresponds to the 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, e.g., 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. The dimension along the long side parallel to the D2 direction of the opening APE141 through which the blue light LB1 is emitted at the exit end 141b is 14 mm or more and 16 mm or less, preferably about 15 mm. The size of the modulation surface of the light modulation element 181 in the long side direction, i.e., the D2 direction, is, for example, 15 mm. The size of the modulation surface of the light modulation element 181 may be selected appropriately within a range from 6.48 mm×11.52 mm for a 0.52 inch type to 19.44 mm×34.56 mm for a 1.5 inch type, for example.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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 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 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 a desired spectral reflectance, as will be described later.

[0023] 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.

[0024] 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.

[0025] 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 -D1 side end 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, and the +D1 side end 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 -D1 side end.

[0026] 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.

[0027] 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.

[0028] Considering the size of the light source 121, the width d1 of the edge parallel to the D2 direction on the -D1 side of the plate-shaped members 241A and 241C is 1 mm or more and 3 mm or less, and preferably 2 mm. The width d2 of the edge parallel to the D2 direction on the +D1 side of the plate-shaped members 241A and 241C is 14 mm or more and 16 mm or less, and preferably 15 mm. The length h1 in the D1 direction of the plate-shaped members 241A, 241B, 241C, and 241D from the incident end 141a to the exit end 141b is 5 mm or more and 25 mm or less.

[0029] 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.

[0030] The material of the plate-shaped member 241 includes at least one of aluminum (Al) and silver (Ag), which are metals, and glass, i.e., silicon dioxide (SiO2), which is an insulating and transparent material. When the material of the plate-shaped member 241 includes Al or Ag, the plate-shaped member 241 increases the heat dissipation property of the light guide element 141 and increases the reflectance of the blue light LB propagating in the internal space SP141. When the material of the plate-shaped member 241 includes glass, the plate-shaped member 241 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.

[0031] In the light guide element 141, in order to increase the reflectance of the blue light LB incident from the incident end 141a in the vicinity of the side surface 141s, 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. A part of the blue light LB incident from the incident end 141a into the internal space SP141 of the light guide element 141 is reflected by the reflective film 251 and travels toward the +D1 side.

[0032] The intensities of the blue light LB1 and LB2 reflected by and emitted from the reflective film 251 differ from each other and depend on the angle of incidence of the blue light LB incident on the reflective film 251. When the reflective film 251 is made of a metal film, the incidence angle dependency of the intensity of the blue light LB emitted from the reflective film 251 changes depending on parameters such as the conditions for vapor deposition of metal particles, for example.

[0033] As described above, for example, when angle α is within a range of 7° to 22° and angle β is within a range of 14° to 36°, reflective film 251 is designed and parameters of reflective film 251 are appropriately determined so that the angle of incidence of blue light LB at which the intensity of blue light LB emitted from reflective surface 141r and reflective film 251 is highest is within a range of 60° to 90°. The relationship between the angle of incidence of blue light LB on reflective surface 141r and reflective film 251 and the intensity of blue light LB emitted from reflective surface 141r and reflective film 251 is obtained by a numerical simulation based on the configuration of blue light emission unit 101 and ray tracing.

[0034] The reflective film 251 is, for example, a metal film that reflects blue light LB1, and is formed by depositing metal particles that form the metal film on the plate surface 241p of the plate-shaped member 241. The metal that forms the metal film includes at least one of Al and Ag. A protective film (not shown) may be provided on the surface of the reflective film 251 opposite to the side of the metal film that contacts the plate-shaped member 241.

[0035] 3 is a side view of the light source 121 and the light guide element 141. The light guide element 141 reflects the blue light LB emitted from the light source 121 within a range of angles up to a large angle with respect to the optical axis, i.e., the blue light LB emitted at a wide angle, by the reflective film 251 and propagates the blue light LB in the internal space SP141, thereby adjusting the beam area of ​​the blue light LB to the size of the emission end 141b and collecting the blue light LB.

[0036] The reflectance, absorptance, and transmittance of the reflective film 251 for the blue light LB are adjusted by the conditions for depositing the metal particles on the plate surface 241p, i.e., the deposition time, the concentration of the metal particles, the thickness of the metal film formed on the plate surface 241p, etc. In the blue light emitting unit 101 of this embodiment, the reflectance of the reflective film 251 for the blue light LB2 is different from the reflectance of the reflective film 251 for the blue light LB1 and is lower than the reflectance of the reflective film 251 for the blue light LB1.

[0037] As shown in FIG. 3, the incident angle θ of the blue light LB incident on the plate surface 241p of the plate-shaped member 241 and the reflective film 251 is 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 The reflectance of the reflective film 251 at each position in the D1 direction for the blue light LB, the density of the metal particles, etc. are set so that the reflectance for the blue light LB2 incident at each position is at least lower than the reflectance for the blue light LB1 incident at the same position.

[0038] Because the reflectance of the reflective film 251 for blue light LB2 is lower than the reflectance for blue light LB1, the light intensity of the blue light LB1 emitted from the emission end 141b of the light guide element 141 is higher than the light intensity of the blue light LB2 emitted from the emission end 141b. The amount of blue light LB1 emitted from the emission end 141b is greater than the amount of blue light LB2 emitted from the emission end 141b. The difference in light amount between the amount of blue light LB2 emitted from the light source 121 and the amount of blue light LB2 emitted from the emission end 141b is greater than the amount of blue light LB2 emitted from the emission end 141b.

[0039] Specifically, the reflectance 251 of the light guide element 141 for the blue light LB2 is lower than the transmittance of the light guide element 141 for the blue light LB2 and the absorptance of the light guide element 141 for the blue light LB2. The reflectance of the reflective film 251 for the blue light LB2 at each position in the D1 direction, the density of the metal particles, and the like are appropriately set so that the reflectance for the blue light LB2 incident at each position is lower than the transmittance and absorptance.

[0040] The reflectance 251 of the light-guiding element 141 for the blue light LB2 is lower than the sum of the transmittance and absorptance of the reflective film 251 of the light-guiding element 141 for the blue light LB2. The sum of the reflectance, transmittance, and absorptance of the reflectance 251 for the blue light LB2 is approximately 100%. That is, the reflectance of the reflective film 251 for the blue light LB2 is at least 50% or more, and preferably 70% or more. The reflectance of the reflective film 251 for the blue light LB2 at each position in the D1 direction and the density of the metal particles are appropriately set so that the reflectance for the blue light LB2 incident at each position is lower than the sum of the transmittance and absorptance.

[0041] Of the blue light LB incident on the reflective film 251, the blue light LB that passes through the reflective film 251 is incident on the plate-shaped member 241, which is a transparent member with respect to the blue light LB, and is emitted to the outside of the light-guiding element 141 from a plate surface 241q opposite to the plate surface 241p of the plate-shaped member 241. When the transmittance of the reflective film 251 of the light-guiding element 141 for the blue light LB is higher than the absorptance, the amount of blue light LB absorbed by the reflective film 251 and the plate-shaped member 241 of the light-guiding element 141 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 becoming distorted due to heat, and suppresses deterioration of the light-guiding element 141 over time.

[0042] As described above, the reflectance, transmittance, and absorptance of the light-guiding element 141 for the blue light LB, and the density of the metal particles with reflectance 251 are set, so the amount of blue light LB2 emitted from the emission end 141b of the light-guiding element 141 is less than the amount of blue light LB1 emitted from the emission end 141b of the light-guiding element 141.

[0043] 1, the collimating element 161 is provided on the optical path of the blue light LB emitted from the light guide element 141, and is disposed on the +D1 side of the light guide element 141 and at a position overlapping with the light guide element 141 in the D2 and D3 directions. The collimating element 161 collimates the blue light LB emitted from the light guide element 141 along the D1 direction.

[0044] 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 LB. 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 to the +D1 side from which the blue light LB 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. Since the collimating element 161 is in contact with the exit end 141b, the blue light LB 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 LB. However, the collimating element 161 may be an optical lens other than a plano-convex lens that can collimate the incident blue light LB, and may be disposed at an appropriate distance from the light guide element 141 in the D1 direction.

[0045] The incident-side polarizing element 171 is provided on the optical path of the blue light LB emitted from the collimating element 161, and is disposed on the +D1 side of the collimating element 161 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.

[0046] 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.

[0047] The blue light LB emitted from the light source 121 includes at least P-polarized light and S-polarized light, and is, for example, randomly polarized. The P-polarized component of the blue light LB emitted from the light source 121 passes sequentially through the light-guiding element 141 and the collimating element 161 as described above, is transmitted through the incident-side polarizing element 171, and is emitted on the +D1 side of the incident-side polarizing element 171. The S-polarized component of the blue light LB, like the P-polarized component, passes sequentially through the light-guiding element 141 and the collimating element 161, but is reflected by the incident surface of the incident-side polarizing element 171 and is emitted on the −D1 side of the incident-side polarizing element 171, or is absorbed by the incident-side polarizing element 171.

[0048] 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 of a first 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 of a second 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.

[0049] 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 LB1 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 first light. The light modulation element 181 emits the image light IB generated by the liquid crystal panel toward the +D1 side along the D1 direction.

[0050] 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 to the +D1 side along the D1 direction. The predetermined polarized light is, for example, P-polarized light.

[0051] 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.

[0052] 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.

[0053] The green light output unit 102 has a light source 122, a light-guiding element 142, and a collimating element 162. Fig. 4 is a schematic diagram of the green light output unit 102, when viewed along the D3 direction. Fig. 5 is a schematic diagram of the green light output unit 102 and the incident-side polarizing element 172, when viewed along the D3 direction.

[0054] 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.

[0055] The light source 122 is composed of, for example, an LED that emits green light LG. In the green light emitting unit 102, in order to optimize the blue wavelength band and intensity of the blue light LB emitted by the blue light emitting unit 101 and the green wavelength band and intensity of the green light LG relative to the red wavelength band and intensity of the red light LR emitted by the red light emitting unit 103, the light source 122 is composed of an LED with a built-in phosphor, and has an LED body 125 made of a semiconductor and a phosphor 124.

[0056] 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 LB, similar to the light source 121. The LED body 125 includes, for example, a GaN-based semiconductor material.

[0057] The phosphor 124 is laminated on an emission 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 fluorescent light 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.

[0058] The green light LG in the green wavelength band, which is fluorescence emitted from the phosphor 124, corresponds to the third light. The green wavelength band corresponds to the third 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, and preferably includes 532 nm.

[0059] 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 light LB3 corresponds to the fourth light. The blue wavelength band of the blue light LB3 corresponds to the fourth wavelength band. The fourth wavelength band is a wavelength band different from the third wavelength band, and is, for example, 450 nm to 490 nm. The amount of blue light LB3 is approximately the same as or less than the amount of green light LG.

[0060] 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.

[0061] The light source 122 may be configured with one LED or a plurality of LEDs as a whole, similar to the light source 121. When the light source 122 is configured with a plurality of LEDs, the plurality of LEDs are arranged in an area occupied by the light source 122 in a plane including the D1 direction and the D3 direction.

[0062] 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.

[0063] 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.

[0064] 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. The size of the light emitting surface 122a of the light source 122 in the D1 and D3 directions is, for example, 0.25 mm or more and 10 mm or less. The area of ​​the light emitting surface of the light source 121 when viewed along the D2 direction is, for example, 0.25 mm 2 ~10mm x 10mm 2 The size of the modulation surface of the light modulation element 182 in the long side direction, i.e., in the D1 direction, is, for example, 15 mm. The size of the modulation surface of the light modulation element 182 is approximately the same as the size of the modulation surface of the light modulation element 181, and may be selected appropriately within a range from, for example, 6.48 mm × 11.52 mm for a 0.52-inch type to 19.44 mm × 34.56 mm for a 1.5-inch type.

[0065] The size of incident end 142a in the plane including the D1 and D3 directions may be equal to the size of light-emitting surface 122a of light source 122 in the plane including the D1 and D3 directions, but is preferably appropriately larger than the size of light-emitting surface 122a in the plane including the D1 and D3 directions. The dimension along the long side parallel to the D1 direction of opening API 142, through which green light LG and blue light LB3 enter at incident end 142a, is 1 mm or more and 3 mm or less, and preferably about 2 mm.

[0066] 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. The dimension along the long side parallel to the D1 direction of the opening APE142 through which the green light LG is emitted at the exit end 142b is 14 mm or more and 16 mm or less, and preferably about 15 mm.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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 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 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 a desired spectral reflectance, as will be described later.

[0071] A ray Lg1, which is a portion of the green light LG incident on the light-guiding element 142, forms an angle with respect to the virtual line VX and the optical axis that is smaller than the angle α or the angle β, and propagates directly from the incident end 142a to the exit end 142b without being incident on the reflecting surface 142r even once. A ray Lg2, which is the remaining portion of the green light LG incident on the light-guiding element 142, forms an angle with respect to the virtual line VX and the optical axis that is equal to or larger than the angle α or the angle β, and propagates from the incident end 142a to the reflecting surface 142r once, is reflected by the reflecting surface 142r, and then reaches the exit end 142b. The remaining rays of the green light LG incident on the light-guiding element 142, other than the ray Lg2, are incident from the incident end 142a to the reflecting surface 142r two or more times, are repeatedly reflected by the reflecting surface 142r, and then reach the exit end 142b.

[0072] The paths of the green light LG and blue light LB3 in the internal space SP142 vary depending on the angle of incidence at the incident end 142a, and extend over multiple paths with different numbers of reflections at the reflecting surface 142r. As a result, the illuminance distribution of the green light LG and blue light LB3 propagating through the internal space SP142 is homogenized within a plane including the D1 and D3 directions. That is, the light-guiding element 142 homogenizes the illuminance distribution of the incident green light LG within a plane including the D1 and D3 directions. The green light LG and blue light LB3 with homogenized illuminance distribution are emitted from the exit end 142b toward the +D2 side.

[0073] 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.

[0074] 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 light guide element 142 is composed of four trapezoidal plate-shaped members 242, each with its legs connected to one another. The width, i.e., dimensions, of the sides parallel to the D1 or D3 direction on the -D2 side, which corresponds to the upper base of each 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 width, i.e., dimensions, of the sides parallel to the D1 or D3 direction on the +D2 side, which corresponds to the lower base of each 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.

[0075] Considering the size of the light source 122, the width, i.e., dimension, of the edge parallel to the D1 direction on the -D2 side of two opposing plate-like members 242A, 242C in a plane including the D1 and D3 directions is 1 mm or more and 3 mm or less, preferably 2 mm. The width, i.e., dimension, of the edge parallel to the D1 direction on the +D2 side of two opposing plate-like members 242A, 242C is 14 mm or more and 16 mm or less, preferably 15 mm. The length in the D2 direction of each of the plate-like members 242A, 242B, 242C, and 242D from the incident end 142a to the exit end 142b is 5 mm or more and 25 mm or less. The shape of the light guide element 142 is the same as that of the light guide element 141.

[0076] 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.

[0077] The material of the plate-shaped member 242 contains at least one of Al, Ag, and glass, i.e., SiO2, and is preferably the same as the material of the plate-shaped member 241. When the material of the plate-shaped member 242 contains Al or Ag, the plate-shaped member 242 increases the heat dissipation of the light guide element 142 and increases the reflectance of the green light LG and the blue light LB3 propagating in the internal space SP142. When the material of the plate-shaped member 242 contains glass, the plate-shaped member 242 reduces the weight of the light guide element 142 and makes it easier to process the light guide element 142. In this embodiment, it is assumed that the plate-shaped member 242 is made of glass.

[0078] In the reflector of the light-guiding element 142, in order to increase the reflectance of the green light LG incident from the incident end 142a into the light-guiding element 142 near the side surface 142s, a reflective film 252 is provided on the plate surface of the plate-like member constituting the reflector opposite to the side surface 142s, i.e., on the plate surface 242p facing the internal space SP142. A part of the green light LG including the light ray Lg2 incident from the incident end 142a into the internal space SP142 of the light-guiding element 142 and the light ray of the blue light LB3 are reflected by the reflective film 252 and travel toward the +D2 side.

[0079] The intensities of the green light LG and the blue light LB3 reflected by the reflective film 252 and emitted from the reflective film 252 differ from each other and 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 made of a metal film, the incidence angle dependency of the intensities of the green light LG and the blue light LB3 emitted from the reflective film 252 changes depending on parameters such as the conditions for vapor deposition of metal particles, for example.

[0080] As described above, for example, when angle α is within a range of 7° to 22° and angle β is within a range of 14° to 36°, reflective film 252 is designed and parameters of reflective film 252 are appropriately determined so that the angle of incidence of green light LG and blue light LB3 at which the intensities of green light LG and blue light LB3 emitted from reflective surface 142r and reflective film 252 are highest is within a range of 60° to 90°. The relationship between the angle of incidence of green light LG and blue light LB3 on reflective surface 141r and reflective film 252 and the intensities of green light LG and blue light LB3 emitted from reflective surface 141r and reflective film 252 is also obtained by a numerical simulation based on the configuration of green light emission unit 102 and ray tracing.

[0081] The reflective film 252 is, for example, a metal film that reflects green light LG, and is formed by depositing metal particles that form the metal film on the plate surface 242p of the plate-shaped member 242. The metal that forms the metal film includes at least one of Al and Ag. A protective film (not shown) may be provided on the surface of the reflective film 252 opposite to the side of the metal film that contacts the plate-shaped member 242.

[0082] The light-guiding element 142 reflects the green light LG emitted from the light source 122 within a large angle range relative to the optical axis, i.e., the green light LG emitted at a wide angle, by the reflective film 251 and propagates the light in the internal space SP142, thereby adjusting the beam area of ​​the green light LG to the size of the emission end 141b and collecting the light.

[0083] The reflectance, absorptance, and transmittance of the reflective film 252 for the green light LG are adjusted by the conditions for depositing the metal particles on the plate surface 241p, i.e., the deposition time, the concentration of the metal particles, the thickness of the metal film formed on the plate surface 241p, etc. In the green light emitting unit 102 of this embodiment, the reflectance of the reflective film 252 for the green light and blue light LB3 is different from the reflectance of the reflective film 252 for the green light LG and is lower than the reflectance of the reflective film 252 for the green light LG.

[0084] 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 in increases in the D2 direction from the incident end 142a to the exit end 142b, that is, from the -D2 side to the +D2 side. The reflectance of the reflective film 252 at each position in the D2 direction for the green light LG and the density of the metal particles are set so that the reflectance for the blue light LB3 incident at each position is at least lower than the reflectance for the green light LG incident at the same position.

[0085] Because the reflectance of the reflective film 252 for blue light LB3 is lower than the reflectance for green light LG, the light intensity of the green light LG emitted from the emission end 142b of the light-guiding element 142 is higher than the light intensity of the blue light LB3 emitted from the emission end 142b. The amount of green light LG emitted from the emission end 142b is greater than the amount of blue light LB3 emitted from the emission end 142b. The difference in light amount between the amount of blue light LB3 emitted from the light source 122 and the amount of blue light LB3 emitted from the emission end 142b is greater than the amount of blue light LB3 emitted from the emission end 142b.

[0086] Specifically, the reflectance 252 of the light guide element 142 for the blue light LB3 is lower than the transmittance of the light guide element 142 for the blue light LB3 and the absorptance of the light guide element 142 for the blue light LB3. The reflectance of the reflective film 252 for the blue light LB3 at each position in the D2 direction, the density of the metal particles, and the like are appropriately set so that the reflectance for the blue light LB3 incident at each position is lower than the transmittance and absorptance.

[0087] The reflectance 252 of the light-guiding element 142 for the blue light LB3 is lower than the sum of the transmittance and absorptance of the reflective film 252 of the light-guiding element 142 for the blue light LB3. The sum of the reflectance, transmittance, and absorptance of the reflectance 252 for the blue light LB3 is approximately 100%. That is, the reflectance of the reflective film 252 for the blue light LB3 is at least 50% or more, and preferably 70% or more. The reflectance of the reflective film 252 for the blue light LB3 at each position in the D2 direction and the density of the metal particles are appropriately set so that the reflectance for the blue light LB3 incident at each position is lower than the sum of the transmittance and absorptance.

[0088] Of the green light LG and blue light LB3 incident on the reflective film 252, the green light LG and blue light LB3 that pass through the reflective film 252 enter the plate-shaped member 242, which is transparent to the green light LG and blue light LB3, and are emitted to the outside of the light-guiding element 142 from plate surface 242q opposite to plate surface 242p of the plate-shaped member 242. When the transmittance of the reflective film 252 of the light-guiding element 142 for the green light LG and blue light LB3 is higher than the absorptance, the green light LG and blue light LB3 absorbed by the reflective film 252 and plate-shaped member 242 of the light-guiding element 142 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 warping due to heat, and suppresses deterioration of the light-guiding element 142 over time.

[0089] 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 density of the metal particles having a reflectance of 252 are set, so that the amount of blue light LB3 emitted from the emission end 142b of the light-guiding element 142 is less than the amount of green light LG emitted from the emission end 142b of the light-guiding element 142.

[0090] The collimating element 162 is provided on the optical path of the green light LG 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 LG emitted from the light guide element 142 along the D2 direction.

[0091] The collimating element 162 is, for example, a plano-convex lens, and has an incident surface 162a consisting of a flat surface perpendicular to the D2 direction, and an exit surface 162b consisting of a convex curved surface protruding toward the exit side of the blue light LB. 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 LG is exited from the collimating element 162, and is further on the -D2 side of the light-guiding element 142. The incident surface 162a 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 LG exiting 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 LG. However, the collimating element 162 may be an optical lens other than a plano-convex lens that can collimate the incident green light LG, and may be disposed at an appropriate distance from the light-guiding element 142 in the D2 direction.

[0092] 5, a light ray Lg1, which is a part of the green light LG incident on the light-guiding element 142, propagates directly from the incident end 142a to the exit end 142b without ever hitting the reflecting surface 142r. A light ray Lg2, which is the remaining part of the green light LG incident on the light-guiding element 142, propagates from the incident end 142a to the reflecting surface 142r once, is reflected by the reflecting surface 142r, and then reaches the exit end 142b. As described above, there are many other paths of the green light LG propagating inside the light-guiding element 142 in addition to the paths of the light rays Lg1 and Lg2.

[0093] 1 and 5, the incident-side polarizing element 172 is provided on the optical path of the green light LG 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.

[0094] The incident-side polarizing element 172 emits a predetermined polarized light of the green light LG emitted from the parallelizing element 162 toward the +D2 side along the D2 direction. The predetermined polarized light is, for example, S-polarized light. 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 includes the predetermined polarized light toward the +D2 side, and reflects or absorbs the other portion of the green light LG toward the -D2 side.

[0095] 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.

[0096] As shown in FIG. 5, the green light LG emitted from the light source 122 is randomly polarized light including at least P-polarized light and S-polarized light. The green light LGS, which is the S-polarized component of the green light LG emitted from the light source 122, and the green light LGP, which is the P-polarized component of the green light LG, pass through the light-guiding element 142, where the illuminance distribution is homogenized by the light-guiding element 142 in a plane including the D1 direction and the D3 direction, and the green light LGS and LGP are emitted toward the +D2 side of the light-guiding element 142. The green light LGS and LGP pass through the collimating element 162 and are collimated by the collimating element 162. The collimated green light LGS and LGP enter the incident-side polarizing element 172 from the -D2 side. The green light LGS passes through the incident-side polarizing element 172 and is emitted toward the +D2 side of the incident-side polarizing element 172. The green light LGP is reflected by the incident surface 172 a of the incident-side polarizing element 172 and is emitted to the −D 2 side of the incident-side polarizing element 172 , or is absorbed by the incident-side polarizing element 172 .

[0097] 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.

[0098] 1, 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 and at a position overlapping 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 a third 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 in a fourth wavelength band is color light that is not subject to conversion into image light by light modulation element 182 and does not contribute to the predetermined color balance of the image projected by projector 301.

[0099] 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 LG incident from the incident-side polarizing element 172 by operation of the switching element in response to the electrical signal, thereby generating green image light IG. The image light IG corresponds to the second light. The light modulation element 182 emits the image light IG generated by the liquid crystal panel toward the +D2 side along the D2 direction.

[0100] 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 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] The light source 123 is configured, for example, by an LED that emits red light LR. The LED that emits the red light LR contains, for example, aluminum gallium indium phosphide (AlGaInP) as a light emitter. The red light LR in the red wavelength band includes red light LR1 in a fifth wavelength band and red light LR2 in a sixth wavelength band. If the light source 123 is configured by an LED, the red wavelength band is wider than if it is configured by an LD. The red wavelength band is, for example, a wavelength band of 590 nm to 700 nm. The fifth wavelength band is, for example, 590 nm to 650 nm, and preferably includes 630 nm. The sixth wavelength band is a wavelength band different from the fifth wavelength band, for example, 650 nm to 700 nm. The sixth wavelength band is a wavelength band longer than the fifth wavelength band and closer to the infrared wavelength band than the fifth wavelength band. The red light LR1 corresponds to the fifth light. The red light LR2 corresponds to the sixth light.

[0105] In the red light LR, the light intensity of the red light LR1 is approximately the same as that of the red light LR2. In a description common to the red light LR1 and LR2, the red light LR1 and LR2 may be collectively referred to as the red light LR.

[0106] 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.

[0107] 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.

[0108] 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 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.

[0109] The incident end 143a corresponds to a third incident end and extends parallel to a plane including the D2 and D3 directions. The shape of the incident end 143a when viewed from the D1 direction is the same as the shape of the light emitting surface of the light source 123 when viewed from the same direction, and is, for example, rectangular, specifically, oblong. The size of the light emitting surface of the light source 123 in the D2 and D3 directions is, for example, 0.25 mm or more and 10 mm or less. The area of ​​the light emitting surface of the light source 123 when viewed along the D1 direction is, for example, 0.25 mm 2 ~10mm x 10mm 2 is.

[0110] The size of incident end 143a in the plane including the D2 and D3 directions may be equal to the size of the light-emitting surface of light source 123 in the plane including the D2 and D3 directions, but is preferably appropriately larger than the size of the light-emitting surface of light source 123 in the plane including the D2 and D3 directions. The dimension along the long side parallel to the D2 direction of the opening into which red light LR is incident at incident end 143a is 1 mm or more and 3 mm or less, and preferably about 2 mm.

[0111] The exit end 143b corresponds to the 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 similar to the modulation surface of the light modulation element 183 when viewed from the same direction, e.g., rectangular. The size of the exit end 143b in the plane including the D2 and D3 directions is equivalent to the size of the modulation surface of the light modulation element 183 in the plane including the D2 and D3 directions. The dimension along the long side parallel to the D2 direction of the opening from which the red light LR1 is emitted at the exit end 143b is 14 mm or more and 16 mm or less, preferably approximately 15 mm. The size of the modulation surface of the light modulation element 183 in the long side direction, i.e., the D2 direction, is, for example, 15 mm. The size of the modulation surface of the light modulation element 183 may be appropriately selected within a range from 6.48 mm×11.52 mm for a 0.52 inch type to 19.44 mm×34.56 mm for a 1.5 inch type.

[0112] 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.

[0113] 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, the internal space surrounded by the incident end 143a, the exit end 143b, and the reflecting surface 143r is the region through which the red light LR propagates. The size of the internal space surrounded by the incident end 143a, the exit end 143b, and the reflecting surface 143r in a plane including the D2 and D3 directions increases as the distance from the +D1 side to the -D1 side in the D1 direction increases. Furthermore, the shape of the internal space surrounded by the incident end 143a, the exit end 143b, and the reflecting surface 143r 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 the distance from the +D1 side to the -D1 side increases.

[0114] 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 an imaginary line (not shown) perpendicular to the incident end 143a and the optical axis, and move away from the imaginary line within a plane including the D2 and D3 directions as the light 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.

[0115] 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 of the rectangular shape, including the short side parallel to the D3 direction, with respect to the virtual line and the optical axis, is preferably within a range of 7° to 22°. The predetermined angle β formed by the side surface 143s and the reflecting surface 143r of the rectangular shape, including the long side parallel to the D2 direction, with respect to the virtual line and the optical axis, is preferably 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 a desired spectral reflectance, as will be described later.

[0116] A portion of the red light LR incident on the light-guiding element 143 forms an angle with respect to the virtual line and the optical axis that is smaller than a predetermined angle, and propagates directly from the incident end 143a to the exit end 143b without being incident on the reflecting surface 143r even once. The remaining portion of the red light LR incident on the light-guiding element 143 forms an angle with respect to the virtual line and the optical axis that is equal to or larger than a predetermined angle, and is incident on the reflecting surface 143r from the incident end 143a one or more times, and reaches the exit end 143b after being reflected by the reflecting surface 143r. The path of the red light LR in the internal space surrounded by the incident end 143a, the exit end 143b, and the reflecting surface 143r 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.

[0117] The illuminance distribution of the red light LR propagating through the internal space surrounded by the incident end 143a, the exit end 143b, and the reflecting surface 143r is uniformized 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 from the exit end 143b to the -D1 side.

[0118] 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.

[0119] 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 reflector is composed of four trapezoidal plate-like members 243, each with its legs connected to one another. The width, i.e., dimensions, of the sides parallel to the D2 or D3 direction on the +D1 side, which corresponds to the upper base of each of the four plate-like members 243, are set according to the incident end 143a and the size of 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, which corresponds to the lower base of each of the four plate-like members 243, are set according to the exit end 143b and the size of the modulation surface of the light modulation element 183 in the D2 or D3 direction.

[0120] Considering the size of the light source 123, the width, i.e., dimension, of the edge of the plate-shaped member 243 on the +D1 side parallel to the D2 direction is 1 mm or more and 3 mm or less, and preferably 2 mm. The width, i.e., dimension, of the edge of the plate-shaped member 243 on the -D1 side parallel to the D2 direction is 14 mm or more and 16 mm or less, and preferably 15 mm. 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 or more and 25 mm or less. The shape of the light-guiding element 143 is the same as the shapes of the light-guiding elements 141 and 142.

[0121] The material of the plate-shaped member 243 contains at least one of Al, Ag, and glass, i.e., SiO2, and is preferably the same as the material of the plate-shaped members 241 and 242. When the material of the plate-shaped member 243 contains Al or Ag, the plate-shaped member 243 increases the heat dissipation of the light guide element 143 and increases the reflectance of the blue light LB propagating in the internal space. When the material of the plate-shaped member 243 contains glass, the plate-shaped member 243 reduces the weight of the light guide element 143 and makes it easier to process the light guide element 143. In this embodiment, it is assumed that the plate-shaped member 243 is made of glass.

[0122] The four plate-shaped members 243 are cut into trapezoidal shapes from a base material in which a reflective film 253 is formed on one plate surface of a plate-shaped substrate made of the same material as the plate-shaped member 243. As described above, if the material of the plate-shaped member 243 is the same as the material of the plate-shaped member 241 and the configuration of the reflective film 253 is the same as the configuration of the reflective film 251, the plate-shaped member 243 is cut out from the same base material 248 as the plate-shaped member 241. As described above, of the four plate-shaped members 243 cut out, a side portion corresponding to one leg of a first plate-shaped member 243 is connected to a side portion corresponding to one leg of a second plate-shaped member 243. A side portion corresponding to the other leg of the second plate-shaped member 243 is connected to a side portion corresponding to one leg of a third plate-shaped member 243. A side portion corresponding to the other leg of the third plate-shaped member 243 is connected to a side portion corresponding to one leg of a fourth plate-shaped member 243. The side portion of the fourth plate-shaped member 243 corresponding to the leg on the other side is connected to the side portion of the first plate-shaped member 243 corresponding to the leg on the other side.

[0123] In the reflector of the light-guiding element 143, in order to increase the reflectance of the red light LR incident from the incident end 143a into the light-guiding 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 opposite the side surface 143s of the plate-like member constituting the reflector, i.e., the plate surface facing the internal space of the reflector. Part of the red light LR incident from the incident end 143a into the internal space of the reflector of the light-guiding element 143 is reflected by the reflective film 253 and travels toward the -D1 side.

[0124] The intensity of the red light LR reflected by the reflective film 253 and emitted from the reflective film 253 may depend on the angle of incidence of the red light LR incident on the reflective film 253. When the reflective film 253 is made of a dielectric multilayer metal film, the incidence angle dependency of the intensity of the red light LR emitted from the reflective film 253 changes depending on, for example, parameters at the time of vapor deposition of metal particles, etc.

[0125] As described above, for example, when the angle α is within a range of 7° to 22° and the angle β is within a range of 14° to 36°, the reflective film 253 is designed, and the parameters of the reflective film 253 are appropriately determined, so that the angle of incidence of the red light LR at which the intensity of the red light LR emitted from the reflective surface 143r and the reflective film 253 is highest is within a range of 60° to 90°. The relationship between the angle of incidence of the red light LR on the reflective surface 143r and the reflective film 253 and the intensity of the red light LR emitted from the reflective surface 143r and the reflective film 253 is also obtained by a numerical simulation based on the configuration of the red light emitting unit 103 and ray tracing.

[0126] The reflective film 253 is, for example, a metal film that reflects red light LR1, and is formed by depositing metal particles or metal particles that form the metal film on the plate surface 243p of the plate-shaped member 243. The metal that forms the metal film includes at least one of Al and Ag. A protective film (not shown) may be provided on the surface of the reflective film 253 opposite to the side of the metal film that contacts the plate-shaped member 243.

[0127] The light-guiding element 143 reflects the red light LR emitted from the light source 123 within a range of angles up to a large angle relative to the optical axis, i.e., the red light LR emitted at a wide angle, by the reflective film 253, and propagates the red light LR in the internal space surrounded by the incident end 143a, the exit end 143b, and the reflecting surface 143r, thereby adjusting the beam area of ​​the red light LR to the size of the exit end 143b and collecting the red light LR.

[0128] The reflectance, absorptance, and transmittance of the reflective film 253 for the red light LR are adjusted by the conditions for depositing the metal particles on the plate surface 243p, i.e., the deposition time, the concentration of the metal particles, the thickness of the metal film formed on the plate surface 243p, etc. In the red light emitting unit 103 of this embodiment, the reflectance of the reflective film 253 for the red light LR2 is different from the reflectance of the reflective film 253 for the red light LR1 and is lower than the reflectance of the reflective film 253 for the red light LR1.

[0129] As shown in FIG. 3, the incident angle θ of the red light LB incident on the plate surface 241p of the plate-shaped member 241 and the reflective film 251 is 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 The reflectance of the reflective film 251 at each position in the D1 direction for the red light LR, the density of the metal particles, etc. are set so that the reflectance for the blue light LB2 incident at each position is at least lower than the reflectance for the blue light LB1 incident at the same position.

[0130] Because the reflectance of the reflective film 253 for the red light LR2 is lower than the reflectance for the red light LR1, the light intensity of the red light LR1 emitted from the emission end 143b of the light-guiding element 143 is higher than the light intensity of the red light LR2 emitted from the emission end 143b. The amount of red light LR1 emitted from the emission end 141b is greater than the amount of red light LR2 emitted from the emission end 141b. The difference in light amount between the amount of red light LR2 emitted from the light source 123 and the amount of red light LR2 emitted from the emission end 141b is greater than the amount of red light LR2 emitted from the emission end 141b.

[0131] Specifically, the reflectance of the reflective film 253 of the light-guiding element 143 for the red light LR2 is lower than the transmittance of the reflective film 253 of the light-guiding element 143 for the red light LR2 and the absorptance of the reflective film 253 of the light-guiding element 143 for the red light LR2. The reflectance of the reflective film 253 for the red light LR2 at each position in the D1 direction, the density of the metal particles, and the like are appropriately set so that the reflectance for the red light LR2 incident at each position is lower than the transmittance and absorptance.

[0132] The reflectance of the reflective film 253 of the light-guiding element 143 for the red light LR2 is lower than the sum of the transmittance and absorptance of the reflective film 251 of the light-guiding element 141 for the red light LR2. The sum of the reflectance, transmittance, and absorptance of the reflective film 253 for the red light LR2 is approximately 100%. That is, the reflectance of the reflective film 253 for the red light LR2 is at least 50% or more, and preferably 70% or more. The reflectance of the reflective film 253 for the red light LR2 at each position in the D1 direction and the density of the metal particles are appropriately set so that the reflectance for the red light LR2 incident at each position is lower than the sum of the transmittance and absorptance.

[0133] Of the red light LR incident on the reflective film 253, the red light LR that transmits through the reflective film 253 enters the plate-shaped member 243, which is a transparent member with respect to the red light LR, and is emitted to the outside of the light-guiding element 141 from the plate surface of the plate-shaped member 243 opposite the plate surface 241p and facing the outside. If the transmittance of the reflective film 253 of the light-guiding element 143 for the red light LR is higher than the absorptance, the blue light LB absorbed by the reflective film 251 and the plate-shaped member 241 of the light-guiding element 143 is suppressed, and heat is less likely to accumulate in the light-guiding element 143. This prevents the light-guiding element 143 from changing shape or becoming distorted due to heat, and suppresses deterioration of the light-guiding element 143 over time.

[0134] As described above, the reflectance, transmittance, and absorptance of the light-guiding element 143 for the red light LR, and the density of the metal particles of the reflective film 253 are set, so the amount of red light LR2 emitted from the emission end 143b of the light-guiding element 143 is less than the amount of red light LR1 emitted from the emission end 141b of the light-guiding element 141.

[0135] The collimating element 163 is provided on the optical path of the red light LR 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 LR emitted from the light guide element 143 along the D1 direction.

[0136] 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 LR. 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 LR 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 LR. However, the parallelizing element 163 may be an optical lens other than a plano-convex lens that can parallelize the incident red light LR, and may be disposed at an appropriate distance from the light-guiding element 143 in the D1 direction.

[0137] The incident-side polarizing element 173 is provided on the optical path of the red light LR 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 interval from the light modulation element 183 in the D1 direction.

[0138] The incident-side polarizing element 173 emits a predetermined polarized light of the red light LR emitted from the parallelizing element 163 toward the -D1 side along the D1 direction. The predetermined polarized light is, for example, S-polarized light. 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 that contains the predetermined polarized light toward the -D1 side, and reflects or absorbs the other portion of the red light LR toward 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.

[0139] The red light LR emitted from the light source 123 includes at least P-polarized light and S-polarized light, and is, for example, randomly polarized light. The P-polarized component of the red light LR emitted from the light source 123 passes sequentially through the light-guiding element 143 and the collimating element 163 as described above, is transmitted through the incident-side polarizing element 173, and is emitted on the -D1 side of the incident-side polarizing element 173. The S-polarized component of the red light LR, like the P-polarized component, passes sequentially through the light-guiding element 143 and the collimating element 163, but is reflected by the incident surface of the incident-side polarizing element 173 and is emitted on the +D1 side of the incident-side polarizing element 173, or is absorbed by the incident-side polarizing element 173.

[0140] 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 red light LR1 in a fifth wavelength band of the red light LR based on image information transmitted from an image forming device, such as a computer (not shown), connected to the light modulation element 183 from an external device. Red light LR2 in a sixth wavelength band of the red light LR is color light that is not to be converted into image light by the light modulation element 183, and does not contribute to the predetermined color balance of the image projected by the projector 301.

[0141] 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 LR1 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 third light. The light modulation element 183 emits the image light IR generated by the liquid crystal panel toward the -D1 side along the D1 direction.

[0142] 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 direction and the D3 direction. 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 to the -D1 side along the D1 direction. The predetermined polarized light is, for example, P-polarized light.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] 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.

[0148] 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 incident surface 210c along the D1 direction toward the +D1 side, 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 incident surface 210d along the D2 direction toward the +D2 side, passes through the reflective films 211 and 212, and travels straight toward the +D2 side. The P-polarized light of red image light IR emitted from the emission-side polarizing element 177 enters the inside of the cross dichroic prism 210 from the incident surface 210e along the D1 direction toward the −D1 side, passes through the reflective film 212, is reflected by the reflective film 211, and travels toward the +D2 side. The image light beams IB, IG, and IR emitted from the reflective films 211 and 212 of the cross dichroic prism 210 to the +D2 side are combined to generate full-color image light IM. The cross dichroic prism 210 emits the full-color image light IM from the emission surface 210b to the +D2 side along the D2 direction.

[0149] 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.

[0150] 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.

[0151] The projector 301 of the present embodiment described above includes a light source (first light source) 121, a light source (second light source) 122, 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) LB1 of a first wavelength band and blue light (second light) LB2 of a second wavelength band. The light guide element 141 has a plate-shaped member (first base material) 241 and a reflective film (first reflective film) 251 arranged on the plate-shaped member 241. The light guide element 141 has an incident end (first incident end) 141a into which the blue light beams LB1 and LB2 emitted from the light source 121 are incident, and an exit end (first exit end) 141b from which the blue light beam LB1 is emitted. The light modulation element 181 modulates the blue light LB1 of the first wavelength band emitted from the light guide element 141 based on image information. The projection optical system 250 projects the image light (light) IM emitted from the light modulation element 181. In the projector 301 of this embodiment, the reflectance of the light guide element 141 for the blue light LB2 is lower than the reflectance for the blue light LB1.

[0152] The reflectance of the light guide element 141 includes both the reflectance resulting solely from the reflectance of the reflective film 251, as in the embodiment, and a combined reflectance resulting from the reflectance of the plate-like member 241 and the reflectance of the reflective film 251, which is obtained by adjusting the transmittance of blue light LB in the reflective film 251. In the projector 301 of this embodiment, the reflectance of the light guide element 141 for blue light LB2 in the second wavelength band, which is not used to form a projection image in a subsequent stage, is lower than the reflectance of blue light LB1 in the first wavelength band, which is used to form a projection image. This suppresses unnecessary light when forming a projection image in the light guide element 141, thereby reducing the amount of colored light that is not to be converted into image light among the colored light incident on the light modulation element 181. The projector 301 of this embodiment can suppress the impact on the lifespan of the light modulation element 181 and the degradation of color reproducibility of the projected image. In other words, the projector 301 of this embodiment enables the light modulation element 181 to be used for a long period of time and can improve the color reproducibility of the projected image.

[0153] 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, and a light modulation element (third light modulation element) 183. The light source 122 emits green light (third light) LG of a third wavelength band and blue light (fourth light) LB3 of a fourth wavelength band. The light source 123 emits red light (fifth light) LR1 of a fifth wavelength band and red light (sixth light) LR2 of a sixth wavelength band. The light guide element 142 includes a plate-shaped member (second base material) 242 and a reflective film (second reflective film) 252 arranged on the plate-shaped member 242. The light guide element 142 has an incident end (second incident end) 142a into which the green light LG and blue light LB3 emitted from the light source 122 are incident, and an exit end (second exit end) 142b from which the green light LG is emitted. The light guide element 143 has a plate-shaped member (third base material) 243 and a reflective film (third reflective film) 253 disposed on the plate-shaped member 243. The light guide element 143 has an incident end (third incident end) 143a into which the red light LR1 and LR2 emitted from the light source 123 are incident, and an exit end (third exit end) 143b from which the red light LR1 is emitted. The light modulation element 182 modulates the green light LG of the third wavelength band emitted from the light guide element 142 based on image information. The light modulation element 183 modulates the red light LR1 of the fifth wavelength band emitted from the light guide element 143 based on image information. The projection optical system 250 combines image light IB emitted from the light modulation element 181 with image light IG and IR emitted from the light modulation elements 182 and 183, and projects the generated image light (light) IM. In the projector 301 of this embodiment, the reflectance of the light guide element 142 for blue light LB3 is lower than the reflectance for green light LG. The reflectance of the light guide element 143 for red light LR2 is lower than the reflectance for red light LR1.

[0154] The reflectance of the light guide element 142 includes both the reflectance resulting solely from the reflectance of the reflective film 252 as in the embodiment, and a composite reflectance resulting from the reflectance of the plate-shaped member 242 and the reflectance of the reflective film 252, which is obtained by adjusting the transmittance of green light LG in the reflective film 252, etc. The reflectance of the light guide element 143 also includes both the reflectance resulting solely from the reflectance of the reflective film 253, and a composite reflectance resulting from the reflectance of the plate-shaped member 243 and the reflectance of the reflective film 253, which is obtained by adjusting the transmittance of red light LR in the reflective film 253, etc. In the projector 301 of the embodiment, the reflectance of the light guide element 142 for blue light LB3 in the fourth wavelength band that is not used in forming a projection image in a subsequent stage is lower than the reflectance for green light LG in the third wavelength band that is used in forming a projection image. Therefore, the light guide element 142 suppresses unnecessary light when forming a projection image, and the amount of colored light that is not to be converted into image light among the colored light incident on the light modulation element 182 can be reduced. Since the reflectance of the light guide element 143 for the red light LR2 in the sixth wavelength band that is not used in forming a projection image in a subsequent stage is lower than the reflectance for the red light LR1 in the fifth wavelength band that is used in forming a projection image, the light guide element 143 can suppress unnecessary light when forming a projection image, and the amount of color light that is not to be converted into image light among the color light that enters the light modulation element 183 can be reduced. According to the projector 301 of this embodiment, it is possible to suppress the impact on the life of the light modulation element 181 and the deterioration of the color reproducibility of the projected image. Furthermore, according to the projector 301 of this embodiment, it is possible to combine three colors and expand the color gamut that can be represented in the projected image while suppressing an increase in manufacturing costs.

[0155] In the projector 301 of this embodiment, the first light is blue light LB1 in the blue wavelength band, and the second light is blue light LB2 in a wavelength band on the shorter wavelength side than the first light in the blue wavelength band.

[0156] In the projector 301 of this embodiment, among the colored light of the projected image light, the energy of blue light LB2 in a second wavelength band on the short wavelength side of the blue wavelength band is higher than the energy of blue light LB1 in a first wavelength band on the long wavelength side of the second wavelength band, and the energy of green light LG and red light LR, so that the liquid crystal layer of the light modulation element, etc., that is irradiated with the light deteriorates. According to the projector 301 of this embodiment, the blue light LB2 is absorbed by the light guide element 141, and deterioration of the optical elements and components arranged subsequent to the light guide element 141, including the light modulation element 181, can be suppressed, and the reliability of the optical elements and components arranged subsequent to the light guide element 141 can be improved.

[0157] In the projector 301 of this embodiment, the light source (first light source) 122 converts blue excitation light into fluorescence by irradiating it on the phosphor (fluorescent layer) 124, and emits green light LG. The first light is the green light LG, which is fluorescence converted from part of the excitation light. The second light is blue light LB3, which is another part of the excitation light.

[0158] In projector 301 of this embodiment, when light source 122 having phosphor 124 is considered to be a first light source, blue light LB3 that is not converted by phosphor 124 is unnecessary for generating image light to be projected in a subsequent stage. According to projector 301 of this embodiment, unnecessary light when forming a projection image is suppressed by light guide element 142, and color reproducibility can be improved while preventing the entire device from becoming larger.

[0159] In the projector 301 of this embodiment, the first light is blue light LB. The third light is green light LG. The fifth light is red light LR. The projector 301 of this embodiment can generate and project image light IM with high color reproducibility.

[0160] In the projector 301 of this embodiment, the first wavelength band includes 467 nm. The second wavelength band includes 532 nm. The third wavelength band includes 630 nm. In the projector 301 of this embodiment, the first wavelength band, the second wavelength band, and the third wavelength band include the primary color wavelengths of ITU-R Recommendation BT.2020 or Rec.2020, which are representative color standards. The projector 301 of this embodiment excels in color reproduction and compliance with color standards.

[0161] In the projector 301 of this embodiment, the difference in light quantity between the blue light LB2 emitted from the light source 121 and the blue light LB2 emitted from the emission end 141b of the light-guiding element 141 is greater than the blue light LB2 emitted from the emission end 141b.

[0162] In the projector 301 of this embodiment, it is possible to suppress loss of the blue light LB1 in the light guide element 141, reduce the amount of the blue light LB2, and improve the light utilization efficiency.

[0163] In the projector 301 of this embodiment, the reflectance of the light guide element 141 and the reflective film 251 for the blue light LB2 is lower than the transmittance of the light guide element 141 and the reflective film 251 for the blue light LB2.

[0164] In the projector 301 of this embodiment, the amount of blue light LB2 reflected by the light guide element 141 and the reflective film 251 is less than the amount of blue light LB2 that passes through the light guide element 141 and the reflective film 251. The projector 301 of this embodiment can efficiently suppress unnecessary light, i.e., blue light LB2, that is guided to the exit end 141b by the light guide element 141 when forming a projection image, and can emit the blue light LB2 toward the outside of the light guide element 141 and out of the optical path of the green light LG. Furthermore, if the plate-like member 241 is translucent, heat is less likely to accumulate in the light guide element 141. The projector 301 of this embodiment can prevent deformation or distortion of the light guide element 141 due to heat, and suppress deterioration of the light guide element 141 over time.

[0165] In the projector 301 of this embodiment, the reflectance of the light guide element 141 and the reflective film 251 for the blue light LB2 is lower than the absorptance of the light guide element 141 and the reflective film 251 for the blue light LB2.

[0166] In the projector 301 of this embodiment, the amount of blue light LB2 reflected by the light guide element 141 and the reflective film 251 is less than the amount of blue light LB2 absorbed by the light guide element 141, i.e., the reflective film 251. The projector 301 of this embodiment can prevent stray light from being generated by the blue light LB2. Furthermore, the projector 301 of this embodiment efficiently dissipates heat using the plate-like member 241, and does not require the provision of a member separate from the light guide element 141 for absorbing the blue light LB2, thereby preventing the overall device from becoming larger.

[0167] In the projector 301 of this embodiment, the reflectance of the light guide element 141 for the blue light LB2 is lower than the sum of the transmittance and absorptance of the light guide element 141 for the blue light LB2.

[0168] In the projector 301 of this embodiment, the amount of blue light LB2 guided to the exit end 141b is reduced by the transmission and absorption of the blue light LB2 by the reflective film 251 and the plate-like member 241 of the light guide element 141. The projector 301 of this embodiment makes it possible to easily reduce the amount of blue light LB2 guided to the exit end 141b, and to increase the degree of freedom in designing the light guide element 141, including the conditions and various parameters for vapor deposition of metal particles on the reflective film 251, and the selection of the material for the plate-like member 241.

[0169] In the projector 301 of this embodiment, the plate-like member 241 of the light guide element 141 is made of glass. According to the projector 301 of this embodiment, the light guide element 141 can be made lighter, and the light guide element 141 can be easily manufactured and processed appropriately.

[0170] In the projector 301 of this embodiment, the material of the plate-like member 241 of the light guide element 141 is glass. The reflective film 251 of the light guide element 141 is made of metal and reflects the blue light LB1.

[0171] In the projector 301 of this embodiment, glass, which can easily ensure surface precision, is used as the material for the plate-shaped member 241, and the reflective film 251 is formed on the plate surface 241p, which has high surface precision, of the glass plate-shaped member 241. According to the projector 301 of this embodiment, the optical characteristics of the light guide element 141 for the blue light LB2 can be adjusted with high precision, and the weight of the light guide element 141 can be reduced.

[0172] 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.

[0173] The projector 301 of this embodiment can easily generate rectangular blue light LB1, green light LG, and red light LR1 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.

[0174] 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.

[0175] In the projector 301 of this embodiment, the illuminance distributions of the blue light LB1, the green light LG, and the red light LR1 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 LB1, the green light LG, and the red light LR1 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 LB1, the green light LG, and the red light LR1 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.

[0176] 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 5 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 5 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 5 mm or more and 25 mm or less.

[0177] 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.

[0178] In the projector 301 of this embodiment, the incident end 141a of the light guide element 141 has a width (dimension) d1 in the direction D2 along the long side of the opening API 141 through which the blue light LB enters. The width d1 of the incident end 141a is 1 mm or more and 3 mm or less. The exit end 141b of the light guide element 141 has a width (dimension) d2 in the direction D2 along the long side of the opening APE 141 through which the blue light LB exits. The width d2 of the exit end 141b is 14 mm or more and 16 mm or less. The incident end 142a of the light guide element 142 has a width (dimension) in the direction D1 along the long side of the opening API 142 through which the green light LG enters. The width of the incident end 142a in the direction D1 is 1 mm or more and 3 mm or less. The exit end 142b of the light-guiding element 142 has a width (dimension) in the D1 direction along the long side of the opening APE142 through which the green light LG is emitted. The width of the exit end 142b in the D1 direction is 14 mm or more and 16 mm or less. The incident end 143a of the light-guiding element 143 has a width (dimension) in the D2 direction along the long side of the opening through which the red light LR is incident. The width of the incident end 143a in the D2 direction is 1 mm or more and 3 mm or less. The exit end 143b of the light-guiding element 143 has a width (dimension) in the D2 direction along the long side of the opening through which the red light LR is emitted. The width of the exit end 143b in the D2 direction is 14 mm or more and 16 mm or less.

[0179] In the projector 301 of this embodiment, the widths of the incident end 141a and the exit end 141b of the light guide element 141 are appropriately set. Similarly, the widths of the incident end 142a and the exit end 142b of the light guide element 142 are appropriately set, and the widths of the incident end 143a and the exit end 143b of the light guide element 143 are appropriately set. According to the projector 301 of this embodiment, it is possible to increase the extraction efficiency of the blue light LB and the efficiency of uniforming the illuminance distribution in the light guide element 141. Furthermore, according to the projector 301 of this embodiment, it is possible to increase the extraction efficiency of the green light LG and the efficiency of uniforming the illuminance distribution in the light guide element 142, and it is possible to increase the extraction efficiency of the red light LR and the efficiency of uniforming the illuminance distribution in the light guide element 143.

[0180] [Variations] In the projector 301 of this embodiment, it is assumed that the plate-shaped member 241 is made of glass as described above, but the plate-shaped member 241 may contain Al, Ag, or other metals. 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 element 141 and the plate-shaped member 241, and easily increase the reflectance for color light in the visible wavelength band including blue light LB1, green light LG, and red light LR1.

[0181] Furthermore, in the projector according to the first modified example of this embodiment, the plate-like member 241 of the light guide element 141 is made of metal. The reflective film 251 is a metal film that reflects the blue light LB1. According to the projector according to the first modified example of this embodiment, the thermal conductivity of the plate-like member 241 is increased, and even if the reflective film 251 is unable to absorb all of the blue light LB2 due to the relationship between the thickness of the reflective film 251, which is a metal film, and the amount of incident blue light LB2, the plate-like member 241 efficiently exhausts or dissipates heat, preventing deformation and distortion of the light guide element 141 and suppressing deterioration of the light guide element 141 over time.

[0182] 6 is a perspective view of the light guide element 141 of the blue light output unit 101 of the projector according to a second modification of the present embodiment. As shown in FIG. 6, in the light guide element 141, the reflective film 251 may be disposed on the plate surface 241q facing the outside of the light guide element 141, rather than on the plate surface 241p, of each of the plate-shaped members 241A, 241B, 241C, and 241D. In such a configuration of the second modification, of the blue light LB incident on the reflective surface 141r from the incident end 141a of the light guide element 141 into the internal space SP141, the blue light LB is refracted by the plate-shaped members 241A, 241B, 241C, and 241D made of glass and then enters the reflective film 251. The blue light LB reflected by the reflective film 251 is refracted again by the plate-shaped members 241A, 241B, 241C, and 241D and propagates into the internal space SP141. The blue light LB2 that is incident on and transmitted through the reflective film 251 is emitted to the outside of the light guide element 141. The blue light LB2 that is transmitted through the reflective film 251 and the blue light LB2 that is absorbed by the reflective film 251 do not enter the light modulation element 181.

[0183] In the projector of the second modified example of this embodiment, the plate-shaped member 241 is made of glass. The plate-shaped member 241 has a plate surface (first surface) 241p facing the internal space SP141 of the light guide element 141, and a plate surface (second surface) 241q on the opposite side to the plate surface 241p facing the outside of the light guide element 141. The reflective film 251 is disposed on the plate surface 241q of the plate-shaped member 241, and reflects the blue light LB1.

[0184] In the projector of the second modified example of this embodiment, the reflective film 251 is formed on the plate surface 241q of the plate member 241 made of glass and having high surface accuracy, similar to the case where the reflective film 251 is disposed on the plate surface 241p of the plate member 241. According to the projector of the second modified example of this embodiment, the optical characteristics of the light guide element 141 for the blue light LB2 can be adjusted with high precision, and the weight of the light guide element 141 can be reduced.

[0185] As another modification, in the projector 301 of the present embodiment, when the reflective film 251 is formed of a dielectric multilayer film, parameters such as the number of low-refractive-index layers and high-refractive-index layers constituting the dielectric multilayer film, the refractive index of the low-refractive-index layers, the refractive index of the high-refractive-index layers, and the difference in refractive index between the low-refractive-index layers and the high-refractive-index layers are appropriately set so that the reflectance for blue light LB2 is lower than the reflectance for blue light LB1. Similarly, when the reflective film 252 is formed of a dielectric multilayer film, parameters such as the number of low-refractive-index layers and high-refractive-index layers constituting the dielectric multilayer film, the refractive index of the low-refractive-index layers, the refractive index of the high-refractive-index layers, and the difference in refractive index between the low-refractive-index layers and the high-refractive-index layers are appropriately set so that the reflectance for blue light LB3 is lower than the reflectance for green light LG. When the reflective film 253 is composed of a dielectric multilayer film, parameters such as the number of low-refractive index layers and high-refractive index layers constituting the dielectric multilayer film, the refractive index of the low-refractive index layers, the refractive index of the high-refractive index layers, and the refractive index difference between the low-refractive index layers and the high-refractive index layers are appropriately set so that the reflectance for red light LR2 is lower than the reflectance for red light LR1.

[0186] 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.

[0187] 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 configured by an LED that directly emits green light LG. Furthermore, the polarization components transmitted by the incident-side polarizing plates arranged in the optical paths of the color lights may or may not be common components.

[0188] 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 LB2 that enters the first light modulation element, thereby suppressing deterioration of optical elements and components including the light modulation element and improving the color reproducibility of the projected image.

[0189] 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 in a first wavelength band and second light in a second wavelength band; a first base material and a first reflective film arranged on the first base material, a first light guide element having a first entrance end into which the first light and the second light emitted from the first light source are incident and a first exit end from which the first light is emitted; a first light modulation element that modulates the light in the first wavelength band that is 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 reflectivity of the first light guide element for the second light is lower than the reflectivity for the first light.

[0190] In the configuration of Supplementary Note 1, the reflectance of the first light guide element to the second light in the second wavelength band that is unnecessary for the formation of image light in the light modulation element is lower than the reflectance of the first light in the first wavelength band that is necessary for the formation of image light. With the configuration of Supplementary Note 1, the second light is reduced by the first light guide element that is arranged in a stage preceding the first light modulation element, thereby suppressing deterioration of the light modulation element and improving the color reproducibility of the image projected by the projector.

[0191] (Supplementary Note 2) A second light source that emits third light in a third wavelength band and fourth light in a fourth wavelength band, a third light source that emits fifth light in a fifth wavelength band and sixth light in a sixth wavelength band, a second base material and a second reflective film disposed on the second base material, the second light source having a second incident end into which the third light and the fourth light emitted from the second light source are incident and a second emitting end from which the fourth light is emitted, the second light source having a third base material and a third reflective film disposed on the third base material, the third incident end into which the fifth light and the sixth light emitted from the third light source are incident, and 10. The projector of claim 1, further comprising: a third light guide element having a third exit end that emits the first light; a second light modulation element that modulates the light of the third wavelength band emitted from the second light guide element based on image information; and a third light modulation element that modulates the light of the fifth wavelength band emitted from the third light guide element based on image information, wherein the reflectance of the second light guide element for the fourth light is lower than the reflectance of the third light, and the reflectance of the third light guide element for the sixth light is lower than the reflectance of the fifth light.

[0192] The configuration of Supplementary Note 2 makes it possible to combine the three colors of light, the first light, the second light, and the third light, and to widen the color gamut of the image projected by the projector, while suppressing increases in manufacturing costs.

[0193] (Supplementary Note 3) The projector according to Supplementary Note 1 or Supplementary Note 2, wherein the first light is blue light, and the second light is blue light having a wavelength band shorter than that of the first light.

[0194] The configuration of Supplementary Note 3 enables the first light-guiding element to reduce blue light in the short wavelength band, which may cause deterioration of optical elements and components, and improves the reliability of the light modulation element and other optical elements and components arranged downstream of the first light-guiding element.

[0195] (Appendix 4) The projector according to any one of Appendices 1 to 3, wherein the first light source converts excitation light into fluorescence by irradiating a fluorescent layer with the excitation light and emits the fluorescence, the first light being the fluorescence converted from a part of the excitation light, and the second light being another part of the excitation light.

[0196] In the configuration of Supplementary Note 4, the first light source has a fluorescent layer, and when excitation light from the LED body is irradiated onto the fluorescent layer, the fluorescent layer emits fluorescent light and emits colored light. With the configuration of Supplementary Note 4, unnecessary light is suppressed by the first light guide element, the size of the entire projector device is prevented from increasing, and the color reproducibility of the image projected by the projector can be improved.

[0197] (Appendix 5) The projector of Appendix 2, wherein the first light is blue light, the second light is green light, and the third light is red light.

[0198] The configuration of Supplementary Note 5 makes it possible to generate image light with high color reproducibility.

[0199] (Appendix 6) The projector of Appendix 3, wherein the first wavelength band includes 467 nm, the third wavelength band includes 532 nm, and the fifth wavelength band includes 630 nm.

[0200] With the configuration of Supplementary Note 6, the first, third, and fifth wavebands include the primary color wavelengths of BT.2020, a representative color standard, and therefore color reproduction can be compliant with the standard.

[0201] (Appendix 7) A projector according to any one of appendices 1 to 6, wherein the difference in light intensity between the amount of the second light emitted from the first light source and the amount of the second light emitted from the first emission end is greater than the amount of the second light emitted from the first emission end.

[0202] The configuration of Supplementary Note 7 can reduce the loss of colored light and improve the light utilization efficiency of the projector.

[0203] (Supplementary Note 8) The projector according to any one of Supplementary Notes 1 to 7, wherein the reflectance of the first light guide element for the second light is lower than the transmittance of the first light guide element for the second light.

[0204] The configuration of Supplementary Note 8 makes it difficult for heat to accumulate in the first light guide element, thereby preventing deformation or distortion of the first light guide element and suppressing deterioration of the first light guide element over time.

[0205] (Supplementary Note 9) The projector according to any one of Supplementary Note 1 to Supplementary Note 7, wherein the reflectance of the first light guide element with respect to the second light is lower than the absorptance of the first light guide element with respect to the second light.

[0206] The configuration of Appendix 9 suppresses stray light and eliminates the need to provide a separate optical element or component for absorbing the second light, thereby preventing the projector device from becoming larger overall and enabling efficient heat dissipation at the first base material of the first light guide element.

[0207] (Supplementary Note 10) The projector according to any one of Supplementary Note 1 to Supplementary Note 7, wherein the reflectance of the first light guide element for the second light is lower than the sum of the transmittance and absorptance of the first light guide element for the second light.

[0208] The configuration of Supplementary Note 10 makes it possible to easily suppress the second light guided to the first exit end in accordance with the transmission and absorption of the second light in the first light guide element, thereby increasing the degree of freedom in designing the first light guide element.

[0209] (Appendix 11) The projector of Appendix 8, wherein the material of the first substrate is glass.

[0210] The configuration of Supplementary Note 11 makes it possible to reduce the weight of the first light guide element, and to easily manufacture and process the first light guide element.

[0211] (Appendix 12) The projector of Appendix 9, wherein the material of the first substrate includes aluminum or silver.

[0212] The configuration of Supplementary Note 12 can improve the heat dissipation of the first light guide element, and can easily increase the reflectance of the first reflective film of the first light guide element with respect to the first light.

[0213] (Appendix 13) The projector of Appendix 12, wherein the first reflective film is a metal film that reflects the first light.

[0214] With the configuration of Supplementary Note 13, even if the second light cannot be completely absorbed by the first reflective film due to the relationship between the design values ​​of the thickness of the first reflective film and the amount of incident second light, the heat dissipation and heat dissipation properties of the first light guide element can be obtained.

[0215] (Appendix 14) The projector of Appendix 11, wherein the first reflective film is a metal film that reflects the first light.

[0216] With the configuration of Supplementary Note 14, the first reflective film is formed on the plate surface of the plate-shaped member made of glass with high surface precision, and the optical characteristics of the first reflective film are easily ensured, and the weight of the first light guide element is reduced.

[0217] (Appendix 15) The projector of Appendix 11, wherein the first substrate has a first surface facing the internal space of the first light-guiding element and a second surface facing the outside of the first light-guiding element and opposite the first surface, and the first reflective film is disposed on the second surface, and the first reflective film is a metal film that reflects the first light.

[0218] According to the configuration of Supplementary Note 15, the first reflective film is formed on the plate surface of the plate-shaped member made of glass with high surface precision, and the optical properties of the first reflective film are easily ensured, the weight of the first light-guiding element is reduced, and the degree of freedom in designing the first reflective film is increased.

[0219] (Supplementary Note 16) The projector according to any one of Supplementary Note 1 to Supplementary Note 15, wherein the first light guide element has a rectangular cross-sectional shape, and the second light guide element has a rectangular cross-sectional shape.

[0220] The configuration of Supplementary Note 16 makes it possible to easily generate rectangular first and second lights with uniform illuminance distribution as illumination light.

[0221] (Supplementary Note 17) The projector of any one of Supplementary Notes 1 to 16, wherein a cross-sectional area of ​​the first exit end is larger than a cross-sectional area of ​​the first entrance end, and a cross-sectional area of ​​the second exit end is larger than a cross-sectional area of ​​the second entrance end.

[0222] The configuration of Appendix 17 allows the size of the irradiation area of ​​the first light emitted from the first light source to be matched to the size of the modulation surface of the first light modulation element, making it easy to uniformize the illuminance distribution of the first light, and the size of the irradiation area of ​​the second light emitted from the second light source to be matched to the size of the modulation surface of the second light modulation element, making it easy to uniformize the illuminance distribution of the second light.

[0223] (Supplementary Note 18) The projector according to any one of Supplementary Notes 1 to 4, wherein the length from the first entrance end to the first exit end is 5 mm or more and 25 mm or less.

[0224] The configuration of Appendix 18 makes it possible to efficiently uniformize the illuminance distribution of the first light emitted from the first light source, to efficiently uniformize the illuminance distribution of the second light emitted from the second light source, and to expand the first light and the second light toward the emission side.

[0225] (Appendix 19) The projector of Appendix 11, wherein the first incident end has a dimension along the long side of the opening through which the first light enters, the dimension of the first incident end being 1 mm or more and 3 mm or less, and the first exit end has a dimension along the long side of the opening through which the first light exits, the dimension of the first exit end being 14 mm or more and 16 mm or less.

[0226] The configuration of Supplementary Note 19 can improve the efficiency of taking in the first light into the first light guide element and the efficiency of uniforming the first light, and can improve the efficiency of taking in the second light into the second light guide element and the efficiency of uniforming the second light. [Explanation of symbols]

[0227] 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, 301...projector.

Claims

1. a first light source that emits first light in a first wavelength band and second light in a second wavelength band; a first light guide element including a first base material and a first reflective film disposed on the first base material, the first light guide element having a first incident end into which the first light and the second light emitted from the first light source are incident and a first exit end from which the first light is emitted; a first light modulation element that modulates the light of the first wavelength band 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 reflectance of the first light guide element for the second light is lower than the reflectance for the first light; projector.

2. a second light source that emits third light in a third wavelength band and fourth light in a fourth wavelength band; a third light source that emits fifth light in a fifth wavelength band and sixth light in a sixth wavelength band; a second light guide element including a second base material and a second reflective film disposed on the second base material, the second light guide element having a second incident end into which the third light and the fourth light emitted from the second light source are incident and a second exit end from which the fourth light is emitted; a third light guide element including a third base material and a third reflective film disposed on the third base material, the third light guide element having a third incident end into which the fifth light and the sixth light emitted from the third light source are incident and a third exit end from which the first light is emitted; a second light modulation element that modulates the light of the third wavelength band emitted from the second light guide element based on image information; a third light modulation element that modulates the light of the fifth wavelength band emitted from the third light guide element based on image information; Furthermore, the reflectance of the second light guide element for the fourth light is lower than the reflectance of the second light guide element for the third light, the reflectance of the third light guide element for the sixth light is lower than the reflectance for the fifth light; The projector according to claim 1 .

3. the first light is blue light; the second light is blue light in a wavelength band shorter than that of the first light, The projector according to claim 1 or 2.

4. the first light source irradiates the fluorescent layer with excitation light, converts the excitation light into fluorescence, and emits the fluorescence; the first light is the fluorescent light converted from a part of the excitation light, the second light is another part of the excitation light; The projector according to claim 1 or 2.

5. the first light is blue light; the third light is green light, the fifth light is red light; The projector according to claim 2 .

6. the first wavelength band includes 467 nm; the second wavelength band includes 532 nm; the third wavelength band includes 630 nm; The projector according to claim 2 .

7. a difference in light amount between the second light emitted from the first light source and the second light emitted from the first exit end is greater than the light amount of the second light emitted from the first exit end; The projector according to claim 1 or 2.

8. The reflectance of the first light guide element for the second light is lower than the transmittance of the first light guide element for the second light. The projector according to claim 1 or 2.

9. The reflectance of the first light guide element for the second light is lower than the absorptance of the first light guide element for the second light. The projector according to claim 1 or 2.

10. a reflectance of the first light guide element for the second light being lower than a sum of a transmittance and an absorptance of the first light guide element for the second light; The projector according to claim 1 or 2.

11. The material of the first substrate is glass. The projector according to claim 8 .

12. the material of the first substrate comprises aluminum or silver; The projector according to claim 9.

13. the first reflective film is a metal film that reflects the first light; The projector according to claim 12.

14. the first reflective film is a metal film that reflects the first light; The projector according to claim 11.

15. The first substrate is a first surface facing an internal space of the first light guide element; a second surface facing the outside of the first light guide element and opposite to the first surface; and the first reflective film is disposed on the second surface; the first reflective film is a metal film that reflects the first light; The projector according to claim 11.

16. The first light guide element has a rectangular cross-sectional shape, The cross-sectional shape of the second light guide element is rectangular. The projector according to claim 2 .

17. a cross-sectional area of ​​the first exit end is larger than a cross-sectional area of ​​the first entrance end; The cross-sectional area of ​​the second exit end is larger than the cross-sectional area of ​​the second entrance end. The projector according to claim 2 .

18. a length from the first incident end to the first exit end of the optical fiber is 5 mm or more and 25 mm or less; The projector according to claim 1 or 2.

19. the first incident end has a dimension along a long side of an opening into which the first light is incident, the dimension of the first incident end is 1 mm or more and 3 mm or less; the first exit end has a dimension along a long side of an opening through which the first light is emitted, the dimension of the first emission end is equal to or greater than 14 mm and equal to or less than 16 mm; The projector according to claim 1 or 2.

Images