Projector

Abstract

Provided is a projector. The number of components in a projector is reduced, and enlargement is suppressed. A projector is provided with: a first light source that emits first light; a second light source that emits second light having a wavelength band different from that of the first light; a first light guide element that has a first incident end to which the first light is incident and a first exit end to which the first light is emitted, the first light guide element having a first incident end to which the first light is incident and a first exit end to which the first light is emitted; a second light guide element having a second incident end to which the second light is incident, and a second exit end to which the second light is emitted, the second light guide element having a second incident end to which the second light is incident and a second exit end to which the second light is emitted; a first light modulation element that modulates the first light from the first light guide element; a second light modulation element that modulates the second light from the second light guide element; a light synthesis element that synthesizes the first light from the first light modulation element and the second light from the second light modulation element and emits the synthesized light; and a projection optical system that projects the light emitted from the light synthesis element. The spectral reflectance of the second light guide element is the same as that of the first light guide element.

Description

Technical Field

[0001] This utility model relates to a projector. Background Technology

[0002] Conventionally, as a light modulation device for generating image light of the three primary colors, a projector with three liquid crystal panels, i.e., a three-panel projector, is known. For example, Patent Document 1 discloses a projector comprising: a light source device having a light source section and a color separation and synthesis element; an illumination optical system; a color separation and synthesis optical system; and a projection optical system. The light source section emits excitation light from a phosphor. The color separation and synthesis element directs a portion of the light emitted from the light source section onto the phosphor and another portion of the light emitted from the light source section onto a diffuser for reflection. The illumination optical system illuminates the light emitted from the light source device. The color separation and synthesis optical system performs color separation and color synthesis on the light emitted from the illumination optical system. The projection optical system magnifies and projects the color-synthesized image light onto an image display surface such as a screen.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-079820

[0004] In the three-panel projector disclosed in Patent Document 1, after white light is generated using a light source device, a color separation and synthesis optical system, positioned after the light source device, separates the white light into each color. Therefore, the projector disclosed in Patent Document 1 requires not only a light source device but also a color separation and synthesis optical system. As a result, the number of components increases, potentially leading to a larger projector size. In other words, in a three-panel projector, measures to reduce the number of components and prevent excessive size are desired. Utility Model Content

[0005] One embodiment of the present invention provides a projector comprising: a first light source emitting first light of a first wavelength band; a second light source emitting second light of a second wavelength band different from the first wavelength band; a first light guide element having a first incident end and a first exit end, wherein the first light emitted from the first light source is incident on the first incident end and the first exit end emits the first light; a second light guide element having a second incident end and a second exit end, wherein the second light emitted from the second light source is incident on the second incident end and the second exit end emits the second light; a first light modulation element modulating the first light emitted from the first light guide element based on image information; a second light modulation element modulating the second light emitted from the second light guide element based on image information; a light combining element combining the first light emitted from the first light modulation element and the second light emitted from the second light modulation element to emit the combined light; and a projection optical system projecting the light emitted from the light combining element. The spectral reflectivity of the second reflective film is the same as that of the first reflective film. Attached Figure Description

[0006] Figure 1 This is a schematic diagram illustrating the structure of a projector according to one embodiment.

[0007] Figure 2 yes Figure 1 A three-dimensional diagram of the light guide element of the blue light emission section of the projector.

[0008] Figure 3 Is with Figure 2 A schematic diagram relating to the plate-shaped component of the light guide element and the reflective film.

[0009] Figure 4 yes Figure 1 A schematic diagram of the green light emitting section of a projector.

[0010] Figure 5 yes Figure 1 A schematic diagram of the green light emitting section and the incident side polarizing element of the projector.

[0011] Label Explanation

[0012] 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. Detailed Implementation

[0013] The embodiments of this utility model will now be described with reference to the accompanying drawings. In the drawings, the scale of the dimensions has sometimes been changed to facilitate observation of the structural elements.

[0014] First, refer to Figures 1 to 5 One embodiment of this utility model will be described. Figure 1 This is a schematic diagram illustrating the structure of a projector 301 according to one embodiment of the present invention. The projector 301 is an image display device equipped with three liquid crystal panels as light modulation devices; it is a so-called three-panel projector. Figure 1 As shown, the projector 301 includes a blue light emitting section 101, a green light emitting section 102, a red light emitting section 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.

[0015] Blue light LB is emitted from the blue light emitting unit 101. In the following description, the axial direction parallel to the optical axis of the blue light LB emitted from the blue light emitting unit 101 is defined as the D1 direction. One side of the D1 direction is defined as the -D1 side, and the side of the D1 direction opposite to the -D1 side is defined as the +D1 side. The direction perpendicular to the D1 direction within the plane containing the optical axis of the blue light LB is defined as the D2 direction. One side of the D2 direction is defined as the -D2 side, and the side of the D2 direction opposite to the -D2 side is defined as the +D2 side. The direction perpendicular to both the D1 and D2 directions is defined as the D3 direction. The blue light LB emitted from the blue light emitting unit 101 travels along the D1 direction toward the +D1 side.

[0016] The blue light emitting section 101 includes a light source 121, a light guide element 141, and a parallelizing element 161. The light source 121 is supported by a substrate 111. The light source 121 is disposed on the +D1 side of a plate surface in the substrate 111 that is parallel to a surface including directions D2 and D3. The emitting surface of the light source 121 is arranged substantially parallel to the surface including directions D2 and D3, and is located on the opposite side of the surface of the light source 121 that is in contact with the +D1 side of the substrate 111 in the D1 direction. The light source 121 is equivalent to a first light source, emitting blue light LB in the blue band of the visible spectrum. The blue band is equivalent to the first band. The blue light LB is equivalent to the first light. The blue light LB is emitted from the emitting surface of the light source 121 towards the +D1 side, centered on an axis passing through the center of the emitting surface of the light source 121 and parallel to the D1 direction, according to a predetermined radiation angle. The blue band is, for example, the 430nm to 500nm band, preferably including 467nm.

[0017] The light source 121 is, for example, a light-emitting diode (LED) that emits blue light LB. The LED emitting blue light LB uses a gallium nitride (GaN)-based semiconductor material as the light emitter, which has excellent light extraction efficiency. Furthermore, the light source 121 can be composed of a single LED or multiple LEDs as a whole. When the light source 121 is composed of multiple LEDs, the multiple LEDs are arranged in the area occupied by the light source 121 within a plane including the D2 and D3 directions.

[0018] The light source 121 can also be constructed from a laser diode (LD) containing GaN-based semiconductor materials. When an LED is used for the light source 121, the cost of the light source 121 can be reduced, and the speckle noise of the blue light LB in the image light IM projected onto the screen SCR can be decreased. On the other hand, when an LD is used for the light source 121, high output and high efficiency of the blue light LB emitted from the light source 121 can be achieved.

[0019] The substrate 111, for example, is made of metal and also functions as a heat dissipation component that receives heat from the light source 121 that emits blue light LB and releases that heat to the outside space.

[0020] A light guide element 141 is disposed in the optical path of the blue light LB emitted from the light source 121, and is positioned on the +D1 side of the light source 121 and overlapping the light source 121 in the D2 and D3 directions. The light guide element 141 is equivalent to a first light guide element, having an incident end 141a on the -D1 side in the D1 direction, an emission end 141b on the +D1 side, and a side surface 141s and a reflective surface 141r extending in the D1 direction between the incident end 141a and the emission end 141b.

[0021] The incident end 141a corresponds to the first incident end and extends parallel to the surface encompassing directions D2 and D3. The shape of the incident end 141a when viewed from direction D1 is the same as the shape of the emitting surface of the light source 121 when viewed from the same direction, for example, it is rectangular, specifically a rectangle. The dimensions of the emitting surface of the light source 121 in directions D2 and D3 are, for example, 0.25 mm or more and 10 mm or less. The area of ​​the emitting surface of the light source 121 when viewed along direction D1 is, for example, 0.25 mm × 0.25 mm to 10 mm × 10 mm.

[0022] The size of the incident end 141a in the plane encompassing both directions D2 and D3 can be the same as the size of the emitting surface of the light source 121 in the plane encompassing both directions D2 and D3, but is preferably moderately larger than the size of the emitting surface of the light source 121 in the plane encompassing both directions D2 and D3. At the incident end 141a, the dimension of the long side of the opening API 141 for the incidence of blue light LB, parallel to the D2 direction, is, for example, 1 mm or more and 3 mm or less, preferably around 2 mm.

[0023] The emitting end 141b corresponds to the first emitting end, extends parallel to the plane encompassing directions D2 and D3, and is larger than the incident end 141a. The shape of the emitting end 141b when viewed from direction D1 is the same as the modulation surface of the light modulation element 181 when viewed from the same direction, for example, it is rectangular. The size of the emitting end 141b within the plane encompassing directions D2 and D3 is equal to the size of the modulation surface of the light modulation element 181 within the plane encompassing directions D2 and D3. At the emitting end 141b, the dimension of the long side of the opening APE 141 emitting blue light LB, parallel to direction D2, is 14 mm or more and 16 mm or less, preferably about 15 mm. The size of the long side direction of the modulation surface of the light modulation element 181, i.e., direction D2, is, for example, 15 mm. Furthermore, the size of the modulation surface of the optical modulation element 181 can be appropriately selected, for example, from 6.48mm × 11.52mm for the 0.52-inch type to 19.44mm × 34.56mm for the 1.5-inch type.

[0024] The side surface 141s and the reflecting surface 141r connect the periphery of the incident end 141a and the periphery of the emission end 141b in the D1 direction.

[0025] Blue light LB emitted from light source 121 enters light guide element 141 from incident end 141a. Within light guide element 141, the internal space SP141, surrounded by incident end 141a, emission end 141b, and reflecting surface 141r, is the region where blue light LB propagates. The size of internal space SP141 within the plane encompassing directions D2 and D3 increases as it moves from the -D1 side towards the +D1 side in direction D1. As it moves from the -D1 side towards the +D1 side, the shape of internal space SP141 on the plane encompassing directions D2 and D3 changes from the shape of the emitting surface of light source 121 as viewed from direction D1 to the shape of the modulation surface of light modulation element 181.

[0026] The side surface 141s of the light guide element 141 and the reflecting surface 141r provided on the side surface 141s, as described later, form a predetermined angle with respect to the imaginary line perpendicular to the incident end 141a and the optical axis. As the light guide element moves from the -D1 side to the +D1 side, it moves away from the imaginary line in the plane including the D2 and D3 directions. The blue light LB incident on the light guide element 141 propagates from the -D1 side to the +D1 side in the internal space SP141 surrounded by the incident end 141a, the emission end 141b, and the reflecting surface 141r.

[0027] The modulation surface of the light modulation element 181, when viewed along the D1 direction, is rectangular, and the emitting surface of the light source 121, when viewed along the D1 direction, is also rectangular. The angle α (cone angle) formed by the rectangular side 141s (parallel to the D3 direction) and the reflecting surface 141r with respect to the aforementioned imaginary line and optical axis is within the range of 7° to 22°. The angle β (cone angle) formed by the rectangular side 141s (parallel to the D2 direction) and the reflecting surface 141r with respect to the aforementioned imaginary line and optical axis is within the range of 14° to 36°. The preferred ranges of angles α and β are appropriately set through numerical simulations based on the structure of the blue light emitting section 101 and ray tracing, in a manner that ensures the reflective film 251 of the light guide element 141 has the desired spectral reflectivity, as described later.

[0028] A portion of the blue light LB incident on the light guide element 141 forms an angle smaller than a predetermined angle relative to the aforementioned imaginary line and optical axis, and does not incident on 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 greater than a predetermined angle relative to the aforementioned imaginary line and optical axis, and is incident on the reflecting surface 141r more than once from the incident end 141a, is reflected by the reflecting surface 141r, and reaches the exit end 141b. The path of the blue light LB in the internal space SP141 varies depending on the incident angle towards the incident end 141a, involving multiple paths with different numbers of reflections at the reflecting surface 141r.

[0029] The illuminance distribution of the blue light LB propagating towards the +D1 side within the internal space SP141 is homogenized within the plane encompassing both the D2 and D3 directions. That is, the light guide element 141 homogenizes the illuminance distribution of the incident blue light LB within the plane encompassing both the D2 and D3 directions. The blue light LB with its homogenized illuminance distribution is emitted from the emission end 141b towards the +D1 side.

[0030] The light guide element 141 is, for example, a reflector, and is formed as a hollow component. Figure 2 This is a 3D view of the light guide element 141. (See diagram below.) Figure 2 As shown, when viewed along the D1 direction, the light guide element 141 is, for example, formed as a rectangle, narrowing from the emission end 141b to the incident end 141a. When viewed along the D1 direction, the -D1 side end of the reflector frame has the same shape and size as the incident end 141a and the light-emitting surface of the light source 121, while the +D1 side end of the reflector frame has the same shape and size as the emission end 141b and the modulation surface of the light modulation element 181, for example, formed as a rectangle of a different size than the -D1 side end.

[0031] The light guide element 141 is, for example, composed of a plate-shaped component 241 and a reflective film 251. The plate-shaped component 241 corresponds to the first substrate. The reflective film 251 corresponds to the first reflective film. If the shape of the incident end 141a and the emitting end 141b when viewed from the D1 direction is rectangular, as described above, then the reflector is composed of four trapezoidal plate-shaped components 241A, 241B, 241C, and 241D and the reflective film 251. The end edges of the upper bases of the plate-shaped components 241A and 241C, corresponding to the trapezoids, are parallel to the D2 direction and extend along the long side of the incident end 141a. The end edges of the lower bases of the plate-shaped components 241A and 241C, corresponding to the trapezoids, are parallel to the D2 direction and extend along the long side of the emitting end 141b. The end edges of the upper bases of the plate-shaped components 241B and 241D, corresponding to the trapezoids, are parallel to the D3 direction and extend along the short side of the incident end 141a. The lower edge of the trapezoidal base of the plate-shaped components 241B and 241D is parallel to the D3 direction and extends along the short side of the injection end 141b.

[0032] The width, i.e., the dimension, of the side of the plate-shaped components 241A, 241B, 241C, and 241D corresponding to the upper base (-D1 side) parallel to the D2 or D3 direction is set according to the size of the incident end 141a and the emitting surface of the light source 121 in the D2 or D3 direction. The width, i.e., the dimension, of the side of the plate-shaped components 241A, 241B, 241C, and 241D corresponding to the lower base (+D1 side) parallel to the D2 or D3 direction is set according to the size of the emitting end 141b and the modulation surface of the light modulation element 181 in the D2 or D3 direction.

[0033] Taking into account the size of the light source 121, the width d1 of the end 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, preferably 2 mm. The width d2 of the end 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, preferably 15 mm. The length h1 of the plate-shaped members 241A, 241B, 241C, and 241D in the D1 direction from the incident end 141a to the emission end 141b is 5 mm or more and 25 mm or less.

[0034] Figure 3This is a schematic diagram of a substrate having plate-shaped components 241 and a reflective film 251. Plate-shaped components 241A, 241B, 241C, and 241D are cut out in a trapezoidal shape from a base material 248. The reflective film 251 is formed on one surface of a plate-shaped substrate 245 made of the same material as the plate-shaped components 241. Of the four plate-shaped components 241A, 241B, 241C, and 241D cut out as described above, the edge of one leg of plate-shaped component 241A is connected to the edge of one leg of plate-shaped component 241B. The edge of the other leg of plate-shaped component 241B is connected to the edge of one leg of plate-shaped component 241C. The edge of the other leg of plate-shaped component 241C is connected to the edge of one leg of plate-shaped component 241D. The edge of the leg corresponding to the other side of the plate-shaped member 241D is connected to the edge of the leg corresponding to the other side of the plate-shaped member 241A.

[0035] The materials of the plate-shaped component 241 and the plate-shaped substrate 245 include at least one of aluminum (Al) and silver (Ag) as metals, and glass, i.e., silicon dioxide (SiO2), as a transparent material.

[0036] In the light guide element 141, in order to improve the reflectivity of blue light LB incident from the incident end 141a to the light guide element 141 near the side 141s, a reflective film 251, composed of a dielectric multilayer film or the like, is provided on the plate surfaces of the plate-shaped members 241A, 241B, 241C, and 241D that constitute the reflector and face the internal space SP141. A portion of the blue light LB incident from the incident end 141a to the internal space of the reflector of the light guide element 141 is reflected by the reflective film 251 and travels towards the +D1 side.

[0037] The intensity of the blue light LB emitted from the reflective film 251 after being reflected by the reflective film 251 sometimes depends on the angle of incidence of the blue light LB incident on the reflective film 251. When the reflective film 251 is composed of a dielectric multilayer film, the angle-of-incidence dependence of the intensity of the blue light LB emitted from the reflective film 251 varies, for example, depending on 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. When the reflective film 251 is composed of a metal film, for example, the angle-of-incidence dependence of the intensity of the blue light LB emitted from the reflective film 251 varies, for example, depending on parameters such as the density of metal particles.

[0038] The wavelength with the highest reflectivity in the visible band of the reflective film 251 is a wavelength in the green band, preferably within the range of 500 nm to 560 nm, and more preferably 555 nm. The wavelength with the highest reflectivity in the reflective film 251 is also the wavelength to which human vision is most sensitive, thereby improving the visibility of the image projected by the projector 301. The reflectivity in the visible band of the reflective film 251 is 80% to 100%, preferably 85% to 100%, and more preferably 90% to 100%. By adjusting the parameters of the dielectric multilayer film and the metal film constituting the reflective film 251, the reflectivity of the reflective film 251 and the wavelength at which the reflectivity is highest can be effectively controlled.

[0039] As described above, for example, when the angle α is in the range of 7° to 22° and the angle β is in the range of 14° to 36°, the reflective film 251 is designed such that the incident angle of the blue light LB with the highest intensity emitted from the reflective surface 141r is in the range of 60° to 90°. Parameters such as the total number of low-refractive-index layers and high-refractive-index layers constituting the dielectric multilayer film, and the refractive index difference between the low-refractive-index layers and high-refractive-index layers are appropriately determined. The relationship between the incident angle of the blue light LB incident on the reflective surface 141r and the reflective film 251 and the intensity of the blue light LB emitted from the reflective surface 141r and the reflective film 251 is obtained through numerical simulation based on the structure of the blue light emitting section 101 and ray tracing.

[0040] like Figure 1 As shown, the parallelizing element 161 is disposed in the optical path of the blue light LB emitted from the light guide element 141, and is positioned closer to the +D1 side than the light guide element 141 and overlapping with the light guide element 141 in the D2 and D3 directions. The parallelizing element 161 parallelizes the blue light LB emitted from the light guide element 141 along the D1 direction.

[0041] The parallelizing element 161 is, for example, a plano-convex lens, having: an incident surface consisting of a flat surface perpendicular to the D1 direction; and an exit surface 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 parallelizing element 161 is located at least on the -D1 side of the parallelizing element 161, and on the opposite side to the +D1 side from which the blue light LB is emitted from the parallelizing element 161, and further on the -D1 side of the light guide element 141. The incident surface of the plano-convex lens of the parallelizing element 161 is in contact with the exit end 141b of the light guide element 141. By connecting the parallelizing element 161 to the exit end 141b, the blue light LB emitted from the exit end 141b of the light guide element 141 is captured by the parallelizing element 161 to the maximum extent, and the loss of blue light LB can be suppressed. However, the parallelizing element 161 can also be an optical lens other than a plano-convex lens that can parallelize the incident blue light LB, and can also be configured at an appropriate distance from the light guide element 141 in the D1 direction.

[0042] An incident-side polarizing element 171 is disposed in the optical path of the blue light LB emitted from the parallelizing element 161, and is positioned closer to the +D1 side than the parallelizing element 161, overlapping the parallelizing element 161 in both the D2 and D3 directions. The incident-side polarizing element 171 is connected to the optical modulation element 181, for example, from the -D1 side, but it can also be disposed at an appropriate distance from the optical modulation element 181 in the D1 direction. The incident-side polarizing element 171 causes a predetermined polarized light in the blue light LB emitted from the parallelizing element 161 to be emitted along the D1 direction towards the +D1 side. The predetermined polarized light is, for example, S-polarized light.

[0043] The incident-side polarizing element 171 is, for example, a reflective or absorptive polarizing plate having a plate surface parallel to the plane containing the D2 and D3 directions. The incident-side polarizing element 171 allows a portion of the incident blue light LB containing a predetermined polarization to pass through to the +D1 side, and reflects or absorbs another portion of the blue light LB to the -D1 side. Furthermore, when it is desirable to suppress return light and stray light toward the light source 121, the incident-side polarizing element 171 is preferably an absorptive polarizing plate.

[0044] The blue light LB emitted from light source 121 contains at least P-polarized light and S-polarized light, such as randomly polarized light. The S-polarized component of the blue light LB emitted from light source 121 passes sequentially through light guide element 141 and parallelization element 161 as described above, then through incident-side polarization element 171, and exits at a position closer to the +D1 side of incident-side polarization element 171. The P-polarized component of the blue light LB passes sequentially through light guide element 141 and parallelization element 161 in the same manner as the S-polarized component, but is reflected at the incident surface of incident-side polarization element 171 and exits at a position closer to the -D1 side of incident-side polarization element 171, or is absorbed by incident-side polarization element 171.

[0045] An optical modulation element 181 is disposed in the optical path of the blue light LB emitted from the incident-side polarizing element 171, and is positioned closer to the +D1 side than the incident-side polarizing element 171, overlapping with the incident-side polarizing element 171 in the D2 and D3 directions. The optical modulation element 181, equivalent to a first optical modulation element, modulates the blue light LB emitted from the incident-side polarizing element 171 based on image information transmitted by an image forming apparatus such as a computer (not shown). This image forming apparatus is externally connected to the optical modulation element 181.

[0046] The light modulation element 181 is, for example, a transmissive liquid crystal panel. The liquid crystal panel constituting the light modulation element 181 has multiple pixels (not shown). Each pixel has a switching element. The switching element is, for example, a thin-film transistor (TFT). An electrical signal is supplied to the switching element of each pixel, and this electrical signal corresponds to the brightness of the blue light at the relative position of each pixel in the modulation surface of the light modulation element 181 in the image projected by the projector 301. Each pixel modulates the vibration direction of the blue light LB incident from the incident-side polarizing element 171 according to the operation of the switching element corresponding to the aforementioned electrical signal, generating a blue image light IB. The image light IB corresponds to the first light. The light modulation element 181 causes the image light IB generated by the liquid crystal panel to be emitted along the D1 direction towards the +D1 side.

[0047] An emission-side polarizing element 175 is disposed in the optical path of the image light IB emitted from the optical modulation element 181, and is positioned closer to the +D1 side than the optical modulation element 181, overlapping the optical modulation element 181 in the D2 and D3 directions. The emission-side polarizing element 175 is connected to the optical modulation element 181, for example, from the +D1 side, but it can also be disposed with a suitable distance between it and the optical modulation element 181 in the D1 direction. The emission-side polarizing element 175 causes a predetermined polarized light in the image light IB emitted from the optical modulation element 181 to be emitted towards the +D1 side along the D1 direction. The predetermined polarized light is, for example, P-polarized light.

[0048] The exit-side polarizing element 175 is, for example, a reflective or absorptive polarizing plate having a plate surface parallel to the plane containing the D2 and D3 directions. The exit-side polarizing element 175 allows a portion of the incident image light IB containing a predetermined polarization to pass through to the +D1 side, and causes another portion of the image light IB to be reflected or absorbed to the -D1 side. Furthermore, when it is desirable to suppress the return light and stray light to the light modulation element 181, an absorptive polarizing plate is preferably used as the exit-side polarizing element 175.

[0049] The green light emitting section 102 is positioned closer to the blue light emitting section 101 on the +D1 side and on the -D2 side, and is located in the region overlapping with the blue light emitting section 101 in the D3 direction. The green light emitting section 102 emits green light LG. The green light LG emitted from the green light emitting section 102 travels along the D2 direction toward the +D2 side.

[0050] The green light emitting section 102 includes a light source 122, a light guide element 142, and a parallelizing element 162. Figure 4 This is a schematic diagram of the green light emitting section 102, and it is a diagram of the green light emitting section 102 when viewed along the D3 direction. Figure 5 This is a schematic diagram of the green light emitting section 102 and the incident-side polarizing element 172, viewed along the D3 direction. The light source 122 is supported by a substrate 112. The light source 122 is disposed on the +D2 side of a plate surface in the substrate 112 that is parallel to the surface including both the D1 and D3 directions. The emitting surface 122a of the light source 122 is arranged substantially parallel to the surface including both the D1 and D3 directions, and is located on the opposite side of the surface of the light source 122 that is in contact with the +D2 side of the substrate 112 in the D2 direction. The light source 122 is equivalent to a second light source, emitting green light LG in the green band of the visible spectrum. The green band is, for example, the 500nm to 590nm band, preferably including 532nm.

[0051] The light source 122 is, for example, an LED that emits green light LG. In the green light emitting section 102, in order to optimize the green wavelength and intensity of the green light LG relative to the blue wavelength and intensity of the blue light LB emitted by the blue light emitting section 101 and the red wavelength and intensity of the red light LR emitted by the red light emitting section 103, the light source 122 is an LED with a built-in phosphor and has an LED body 125 and a phosphor 124 made of semiconductor.

[0052] The LED body 125 is disposed on the +D2 side 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 contains a GaN-based semiconductor material with excellent light extraction efficiency.

[0053] Furthermore, the light source 122 can also replace the LED body 125 by having an LD containing a GaN-based semiconductor material that emits blue light LB as excitation light. When the light source 122 has an LED body 125, the cost of the light source 122 can be reduced. On the other hand, when the light source 122 has an LD instead of an LED body 125, it is possible to achieve high output and high efficiency of the excitation light, as well as an increase in the amount of green light LG emitted from the light source 122.

[0054] A phosphor 124 is stacked on the emission surface 125a of the LED body 125 on the +D2 side. The phosphor 124 is excited by the light emitted from the LED body 125 as excitation light, and emits green light LG from the emission surface 124a as fluorescence. By appropriately selecting the type and material of the LED body 125 and the phosphor 124, the phosphor 124 excited by the light emitted from the LED body 125 emits green light LG in the green band. In the case where the LED body 125 emits blue light LB as described above, the phosphor 124 may, for example, comprise cerium-doped yttrium aluminum garnet (YAG:Ce) as a transparent ceramic. 3+ ).

[0055] Furthermore, the light source 122 can be composed of a single LED, just like the light source 121, or it can be composed of multiple LEDs as a whole. When the light source 122 is composed of multiple LEDs, multiple LEDs are arranged in the area occupied by the light source 122 within the plane including the D1 and D3 directions.

[0056] The substrate 112, for example, is made of metal and also functions as a heat dissipation component that receives heat from the light source 122 that emits green light LG and releases that heat to the outside space.

[0057] The light guide element 142 is disposed in the optical path of the green light LG emitted from the light source 122, and is positioned on the +D2 side of the light source 122 and overlaps with the light source 122 in the D1 and D3 directions. The light guide element 142 is equivalent to a second light guide element, having an incident end 142a on the -D2 side in the D2 direction, an emission end 142b on the +D2 side, and a side surface 142s and a reflective surface 142r extending in the D2 direction between the incident end 142a and the emission end 142b.

[0058] The incident end 142a corresponds to the second incident end and extends parallel to the surface encompassing directions D1 and D3. The shape of the incident end 142a when viewed from direction D2 is the same as the shape of the emitting surface 122a of the light source 122 when viewed from the same direction; for example, it is rectangular, specifically a rectangle. The size of the emitting surface 122a of the light source 122 in directions D1 and D3 is, for example, 0.25 mm or more and 10 mm or less. The area of ​​the emitting surface of the light source 121 when viewed along direction D2 is, for example, 0.25 mm × 0.25 mm to 10 mm × 10 mm. The size of the long side direction of the modulation surface of the light modulation element 182, i.e., direction D1, is, for example, 15 mm. Furthermore, the size of the modulation surface of the optical modulation element 182 is similar to that of the optical modulation element 181, and can be appropriately selected within the range of 6.48mm × 11.52mm for the 0.52-inch type to 19.44mm × 34.56mm for the 1.5-inch type.

[0059] The size of the incident end 142a in the plane including directions D1 and D3 can be the same as the size of the emitting surface 122a of the light source 122 in the plane including directions D1 and D3, but is preferably moderately larger than the size of the emitting surface 122a in the plane including directions D1 and D3. At the incident end 142a, the dimension of the opening API 142 for the green light LG incident along the long side parallel to the D1 direction is, for example, 1 mm or more and 3 mm or less, preferably about 2 mm.

[0060] The emitting end 142b corresponds to the second emitting end, extends parallel to the plane encompassing directions D1 and D3, and is larger than the incident end 142a. The shape of the emitting end 142b when viewed from direction D2 is the same as the modulation surface of the light modulation element 182 when viewed from the same direction, for example, it is rectangular. The size of the emitting end 142b within the plane encompassing directions D1 and D3 is equal to the size of the modulation surface of the light modulation element 182 within the plane encompassing directions D1 and D3. At the emitting end 142b, the dimension of the long side of the opening APE 142 emitting green light LG, parallel to direction D1, is 14 mm or more and 16 mm or less, preferably around 15 mm.

[0061] The side surface 142s and the reflecting surface 142r connect the periphery of the incident end 142a and the periphery of the emission end 142b in the D2 direction.

[0062] Green light LG emitted from light source 122 enters light guide element 142 from incident end 142a. Within light guide element 142, the internal space SP142, surrounded by incident end 142a, emission end 142b, and reflecting surface 142r, is the region where green light LG propagates. The size of internal space SP142 within the plane encompassing directions D1 and D3 increases as it moves from the -D2 side towards the +D2 side in direction D2. Furthermore, as it moves from the -D2 side towards the +D2 side, the shape of internal space SP142 on the plane encompassing directions D1 and D3 changes from the shape of the emitting surface 122a of light source 122 when viewed from direction D2 to the shape of the modulation surface of light modulation element 182.

[0063] The side surface 142s of the light guide element 142 and the reflective surface 142r provided on the side surface 142s as described later form a predetermined angle with respect to the imaginary line VX perpendicular to the incident end 142a and the optical axis. As it moves from the -D2 side to the +D2 side, it moves away from the imaginary line VX in the plane including the D1 and D3 directions. The green light LG incident on the light guide element 142 propagates from the -D2 side to the +D2 side in the internal space SP142.

[0064] The modulation surface of the light modulation element 182, when viewed along the D2 direction, is rectangular, and the emitting surface 122a of the light source 122, when viewed along the D2 direction, is also rectangular. The angle α formed by the rectangular side 142s (parallel to the D3 direction) and the reflecting surface 142r with respect to the imaginary line VX and the optical axis is between 7° and 22°. The angle β formed by the rectangular side 142s (parallel to the D1 direction) and the reflecting surface 142r with respect to the aforementioned imaginary line and the optical axis is between 14° and 36°. The preferred ranges of angles α and β are appropriately set through numerical simulations based on the structure of the green light emitting section 102 and ray tracing, so that the reflective film 252 of the light guide element 142 has the desired spectral reflectivity, as described later.

[0065] A portion of the green light LG incident on the light guide element 142, Lg1, forms an angle smaller than angle α or angle β with respect to the imaginary line VX and the optical axis. It does not incident on the reflecting surface 142r even once, but propagates directly from the incident end 142a to the exit end 142b. The remaining portion of the green light LG incident on the light guide element 142, Lg2, forms an angle greater than angle α or angle β with respect to the imaginary line VX and the optical axis. It is incident once from the incident end 142a to the reflecting surface 142r, reflected by the reflecting surface 142r, and reaches the exit end 142b. The remaining portion of the green light LG incident on the light guide element 142, excluding Lg2, is incident more than twice from the incident end 142a to the reflecting surface 142r, repeatedly reflected by the reflecting surface 142r, and finally reaches the exit end 142b.

[0066] The path of the green light LG in the internal space SP142 varies depending on the incident angle at the incident end 142a, involving multiple paths with different numbers of reflections at the reflecting surface 142r. Therefore, the illuminance distribution of the green light LG propagating in the internal space SP142 is homogenized within the plane encompassing both directions D1 and D3. That is, the light guide element 142 homogenizes the illuminance distribution of the incident green light LG within the plane encompassing both directions D1 and D3. The green light LG with homogenized illuminance distribution is emitted from the exit end 142b towards the +D2 side.

[0067] Like light guide element 141, light guide element 142 is a hollow reflector composed of a plate-like component. When viewed along the D2 direction, the -D2 side end of the reflector frame has the same shape and size as the incident end 142a and the light-emitting surface 122a of the light source 122, for example, it is formed as a rectangle. The +D2 side end of the reflector frame has the same shape and size as the emitting end 142b and the modulation surface of the light modulation element 182, for example, it is formed as a rectangle of a different size than the -D2 side end.

[0068] The light guide element 142 is composed of a plate-shaped component 242 and a reflective film 252. The plate-shaped component 242 corresponds to the second substrate. The light guide element 142 is constructed by connecting the legs-like sides of four plate-shaped components 242, each having a trapezoidal shape, to each other. The width, i.e., the dimension, of the side of the four plate-shaped components 242 corresponding to the upper base (-D2 side) parallel to the D1 or D3 direction is set according to the size of the incident end 142a and the emitting surface 122a in the D1 or D3 direction. The width, i.e., the dimension, of the side of the four plate-shaped components 242 corresponding to the lower base (+D2 side) parallel to the D1 or D3 direction is set according to the size of the emitting end 142b and the modulation surface of the light modulation element 182 in the D1 or D3 direction.

[0069] Taking into account the size of the light source 122, the width of the end edge parallel to the D1 direction on the -D2 side of the two plate-shaped members facing each other in the plane including the D1 and D3 directions is 1 mm or more and 3 mm or less, preferably 2 mm. The width of the end edge parallel to the D1 direction on the +D2 side of the two plate-shaped members facing each other is 14 mm or more and 16 mm or less, preferably 15 mm. The length of the plate-shaped member in the D2 direction from the incident end 142a to the emission end 142b is 5 mm or more and 25 mm or less. The shape of the light guide element 142 is the same as the shape of the light guide element 141.

[0070] The material of plate-shaped component 242 includes at least one of Al, Ag, and glass, i.e., SiO2, and is preferably the same as the material of plate-shaped component 241.

[0071] Regarding the four plate-shaped components 242, a trapezoidal shape is cut from a base material on which a reflective film 252 is formed on one plate surface of a plate-shaped substrate made of the same material as the plate-shaped components 242. If, as described above, the material of the plate-shaped component 242 is the same as that of the plate-shaped component 241, and the structure of the reflective film 252 is the same as that of the reflective film 251, then the plate-shaped component 242 is cut from a base material 248 shared with the plate-shaped component 241. The edge of one leg of the first plate-shaped component 242, cut as described above, is connected to the edge of one leg of the second plate-shaped component 242. The edge of the other leg of the second plate-shaped component 242 is connected to the edge of one leg of the third plate-shaped component 242. The edge of the other leg of the third plate-shaped component 242 is connected to the edge of one leg of the fourth plate-shaped component 242. The edge of the fourth plate-shaped member 242, corresponding to the other side of the leg, is connected to the edge of the first plate-shaped member 242, corresponding to the other side of the leg.

[0072] Similarly, in the reflector of the light guide element 142, in order to improve the reflectivity of the green light LG incident from the incident end 142a to the light guide element 142 near the side 142s, a reflective film 252, such as a dielectric multilayer film, is provided on the plate surface of the plate component constituting the reflector on the side opposite to the side 142s, i.e., the plate surface facing the internal space SP142. A portion of the green light LG containing the light ray Lg2 incident from the incident end 142a to the internal space SP142 of the light guide element 142 is reflected by the reflective film 252 and travels towards the +D2 side.

[0073] The intensity of green light LG emitted from reflective film 252 after being reflected by reflective film 252 sometimes depends on the angle of incidence of the green light LG incident on reflective film 252. When reflective film 252 is composed of a dielectric multilayer film, the angle of incidence dependence of the intensity of green light LG emitted from reflective film 252 varies, for example, depending on 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 layer, the refractive index of the high-refractive-index layer, and the refractive index difference between the low-refractive-index layer and the high-refractive-index layer. When reflective film 252 is composed of a metal film, for example, the angle of incidence dependence of the intensity of green light LG emitted from reflective film 252 varies, for example, depending on parameters such as the density of metal particles.

[0074] The reflective film 252 of the light guide element 142 has the same spectral reflectivity as the reflective film 251 of the light guide element 141. Specifically, similar to the reflective film 251, the wavelength with the highest reflectivity in the visible band of the reflective film 252 is a wavelength in the green band, preferably in the range of 500 nm or more and 560 nm or less, more preferably 555 nm. The spectral reflectivity of the reflective film 252 in the visible band is 80% or more and 100% or less, preferably 85% or more and 100% or less, more preferably 90% or more and 100% or less.

[0075] During the manufacturing process of reflective films 251 and 252, manufacturing errors such as those affecting the parameters of the dielectric multilayer film sometimes occur. For example, if thickness errors occur on the surfaces of the low-refractive-index and high-refractive-index layers constituting the reflective films 251 and 252, the spectral reflectance of the manufactured dielectric multilayer film may have the same distribution as the intended spectral reflectance, but sometimes it may deviate from the intended spectral reflectance distribution by several nm. Furthermore, even if the thicknesses of the low-refractive-index and high-refractive-index layers constituting the reflective films 251 and 252 are accurate and uniform, the spectral reflectance of the manufactured dielectric multilayer film may sometimes deviate from the intended spectral reflectance by a few percent due to the inclusion or amount of impurities. Even with such manufacturing errors in the dielectric multilayer films 251 and 252, the wavelength difference between the wavelength of maximum reflectance in the spectral reflectance of reflective film 251 and the wavelength of maximum reflectance in the spectral reflectance of reflective film 252 is at least 5 nm or less, and preferably 3 nm or less. The difference between the maximum reflectance of the reflective film 251 and the maximum reflectance of the reflective film 252 is at least 3%. Within this range, it can be said that the reflective reflectance of the reflective film 252 is the same as that of the reflective film 251.

[0076] In the spectral reflectivity of the reflective film 252, the wavelength with the highest reflectivity is also the wavelength with the highest human visual sensitivity, thereby improving the visibility of the image projected by the projector 301. By adjusting the parameters of the dielectric multilayer film and the metal film constituting the reflective film 252, the spectral reflectivity of the reflective film 252 and the wavelength with the highest reflectivity can be effectively controlled.

[0077] As described above, for example, when the angle α is in the range of 7° to 22° and the angle β is in the range of 14° to 36°, the reflective film 252 is designed such that the incident angle of the green light LG, which has the highest intensity emitted from the reflective surface 142r and the reflective film 252, is in the range of 60° to 90°, and the parameters of the dielectric multilayer film are appropriately determined. The relationship between the incident angle of the green light LG incident on the reflective film 252 and the intensity of the green light LG emitted from the reflective film 252 is also obtained through numerical simulation based on the structure of the green light emitting part 102 and ray tracing.

[0078] The parallelizing element 162 is disposed in the optical path of the green light LG emitted from the light guide element 142, and is positioned closer to the +D2 side of the light guide element 142 and overlaps with the light guide element 142 in the D1 and D3 directions. The parallelizing element 162 parallelizes the green light LG emitted from the light guide element 142 along the D2 direction.

[0079] The parallelizing element 162 is, for example, a plano-convex lens, having: an incident surface 162a, which is composed of a flat surface perpendicular to the D2 direction; and an exit surface 162b, which is composed 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 parallelizing element 162 is located at least on the -D2 side of the parallelizing element 162, and on the opposite side from the +D2 side of the green light LG emitted from the parallelizing element 162, and further on the -D2 side of the light guide element 142. The incident surface 162a of the parallelizing element 162 is in contact with the exit end 142b of the light guide element 142. By connecting the parallelizing element 162 to the exit end 142b, the green light LG emitted from the exit end 142b of the light guide element 142 is maximized by the parallelizing element 162, and the loss of green light LG can be suppressed. However, the parallelizing element 162 can also be an optical lens other than a plano-convex lens that can parallelize the incident green light LG, and can also be configured at an appropriate distance from the light guide element 142 in the D2 direction.

[0080] like Figure 4As shown, a portion of the green light LG incident on the light guide element 142, specifically ray Lg1, never strikes the reflecting surface 142r, but instead propagates directly from the incident end 142a to the exit end 142b. The remaining portion of the green light LG incident on the light guide element 142, specifically ray Lg2, strikes the reflecting surface 142r once from the incident end 142a, is reflected by the reflecting surface 142r, and then reaches the exit end 142b. As explained above, the paths of the green light LG propagating inside the light guide element 142 are generated in numerous ways besides the paths of rays Lg1 and Lg2.

[0081] like Figure 1 and Figure 5 As shown, the incident-side polarizing element 172 is disposed in the optical path of the green light LG emitted from the parallelizing element 162, and is positioned closer to the +D2 side than the parallelizing element 162 and overlapping with the parallelizing element 162 in both the D1 and D3 directions. The incident-side polarizing element 172 is connected to the optical modulation element 182, for example, from the -D2 side, but it can also be disposed at a suitable distance from the optical modulation element 182 in the D2 direction.

[0082] The incident-side polarizing element 172 causes a predetermined polarized light in the green light LG emitted from the parallelizing element 162 to exit along the D2 direction toward the +D2 side. The predetermined polarized light is, for example, S-polarized light. The incident-side polarizing element 172 is, for example, a reflective or absorptive polarizing plate having a plate surface parallel to a plane containing both the D1 and D3 directions. The incident-side polarizing element 172 causes a portion of the incident green light LG containing the predetermined polarized light to pass through toward the +D2 side, and causes another portion of the green light LG to be reflected or absorbed toward the -D2 side.

[0083] Furthermore, when it is desirable to suppress reflected and stray light toward the light source 122, the incident-side polarizing element 172 is preferably an absorptive polarizing plate. However, when the light source 122 has a phosphor 124, such as the green light emitting section 102, the light reflected from the reflective polarizing plate can be flexibly used to excite the phosphor 124. Therefore, the incident-side polarizing element 172 can also be a reflective polarizing plate.

[0084] like Figure 5As shown, the green light LG emitted from light source 122 is randomly polarized light containing at least P-polarized and S-polarized light. The S-polarized component of the green light LG emitted from light source 122, i.e., green light LGS, and the P-polarized component of the green light LG, i.e., green light LGP, pass through light guide element 142, and the light guide element 142 is used to homogenize the in-plane illuminance distribution in the D1 and D3 directions, and the light LG is emitted towards a position closer to the +D2 side than light guide element 142. Green light LGS and LGP pass through parallelization element 162 and are parallelized by parallelization element 162. The parallelized green light LGS and LGP are incident on the incident side polarization element 172 from the -D2 side. Green light LGS passes through the incident side polarization element 172 and is emitted towards a position closer to the +D2 side than the incident side polarization element 172. The green light LGP is reflected at the incident surface 172a of the incident polarization element 172 and emitted to a position closer to the -D2 side than the incident polarization element 172, or it is absorbed by the incident polarization element 172.

[0085] The green light LGP reflected from the incident-side polarizing element 172 towards the -D2 side passes sequentially through the parallelizing element 162 and the light guiding element 142, traveling along the D2 direction towards the -D2 side. It is focused within a plane encompassing both the D1 and D3 directions and incident on 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 towards the -D2 side, and green light LG, containing green light LGS and LGP, is emitted again from the emission surface 124a towards the +D2 side. The incident-side polarizing element 172 is composed of a reflective polarizing plate, thus allowing the polarized light LG that does not pass through the incident-side polarizing element 172 to re-enter the phosphor 124 of the light source 122, facilitating the excitation and emission of the phosphor 124.

[0086] like Figure 1 As shown, the optical modulation element 182 is disposed in the optical path of the green light LG emitted from the incident-side polarizing element 172, and is positioned closer to the +D2 side than the incident-side polarizing element 172, overlapping with the incident-side polarizing element 172 in the D1 and D3 directions. The optical modulation element 182 is equivalent to a second optical modulation element, which modulates the green light LG emitted from the incident-side polarizing element 172 based on image information transmitted by an image forming apparatus such as a computer (not shown). This image forming apparatus is externally connected to the optical modulation element 182.

[0087] The light modulation element 182 is, for example, a transmissive liquid crystal panel. The liquid crystal panel constituting the light modulation element 182 has multiple pixels (not shown). Each pixel has a switching element. The switching element is, for example, a TFT. An electrical signal is supplied to the switching element of each pixel, and this electrical signal corresponds to the brightness of the green light at the relative position of each pixel in the modulation surface of the light modulation element 182 in the image projected by the projector 301. Each pixel modulates the vibration direction of the green light LG incident from the incident-side polarizing element 172 according to the operation of the switching element corresponding to the aforementioned electrical signal, generating green image light IG. The image light IG corresponds to the second light. The light modulation element 182 causes the image light IG generated by the liquid crystal panel to be emitted along the D2 direction towards the +D2 side.

[0088] An emission-side polarizing element 176 is disposed in the optical path of the image light IG emitted from the optical modulation element 182, and is positioned closer to the +D2 side of the optical modulation element 182, overlapping the optical modulation element 182 in both the D1 and D3 directions. The emission-side polarizing element 176 is connected to the optical modulation element 182, for example, from the +D2 side, but it can also be disposed with a suitable distance between it and the optical modulation element 182 in the D2 direction. The emission-side polarizing element 176 causes a predetermined polarized light in the image light IG emitted from the optical modulation element 182 to be emitted along the D2 direction towards the +D2 side. The predetermined polarized light is, for example, P-polarized light.

[0089] The exit-side polarizing element 176 is, for example, a reflective or absorptive polarizing plate having a plate surface parallel to the plane containing both directions D1 and D3. The exit-side polarizing element 176 allows a portion of the incident image light IG containing a predetermined polarization to pass through to the +D2 side, and causes another portion of the image light IG to be reflected or absorbed to the -D2 side. Furthermore, when it is desirable to suppress the return light and stray light to the light modulation element 182, an absorptive polarizing plate is preferred as the exit-side polarizing element 176.

[0090] The red light emitting section 103 is positioned at a +D1 side closer to the green light emitting section 102, and is located in the region overlapping with the blue light emitting section 101 in the D2 and D3 directions. The red light emitting section 103 emits red light LR. The red light LR emitted from the red light emitting section 103 travels along the D1 direction towards the -D1 side.

[0091] The red light emitting section 103 includes a light source 123, a light guide element 143, and a parallelizing element 163. The light source 123 is supported by a substrate 113. The light source 123 is disposed on the -D1 side of a plate surface of the substrate 113 that is parallel to the surface including the D2 and D3 directions. The emitting surface of the light source 123 is arranged substantially parallel to the surface including the D2 and D3 directions, and is located on the opposite side of the surface of the light source 123 that is in contact with the -D1 side of the substrate 113 in the D1 direction. The light source 123 acts as a third light source, emitting red light (LR) in the red band of the visible spectrum. The red band is, for example, the 590 nm to 700 nm band, preferably including 630 nm.

[0092] The light source 123 is, for example, composed of an LED that emits red light (LR). The LED emitting red light (LR) contains aluminum gallium indium phosphide (AlGaInP) as the light emitter, which has excellent light extraction efficiency. Furthermore, the light source 123 can be composed of a single LED or multiple LEDs as a whole. When the light source 123 is composed of multiple LEDs, multiple LEDs are arranged in the area occupied by the light source 123 within a plane including the D2 and D3 directions.

[0093] The light source 123 can also be constructed using an LD containing AlGaInP. When an LED is used for the light source 123, the cost of the light source 123 can be reduced, and the speckle noise of the red light LR in the image light IM projected onto the screen SCR can be decreased. On the other hand, when an LD is used for the light source 123, high output and high efficiency of the red light LR emitted from the light source 123 can be achieved.

[0094] The substrate 113, for example, is made of metal and also functions as a heat dissipation component that receives heat from the light source 123 that emits red light LR and releases that heat to the outside space.

[0095] The light guide element 143 is disposed in the optical path of the red light LR emitted from the light source 123, and is positioned on the -D1 side closer to the light source 123 and overlapping with the light source 123 in the D2 and D3 directions. The light guide element 143 is equivalent to the third light guide element, and has an incident end 143a on the +D1 side in the D1 direction, an emission end 143b on the -D1 side, and a side surface 143s and a reflective surface 143r extending in the D1 direction between the incident end 143a and the emission end 143b.

[0096] The incident end 143a corresponds to the third incident end and extends parallel to the surface encompassing directions D2 and D3. The shape of the incident end 143a when viewed from direction D1 is the same as the shape of the emitting surface of the light source 123 when viewed from the same direction, for example, it is rectangular, specifically a rectangle. The dimensions of the emitting surface of the light source 123 in directions D2 and D3 are, for example, 0.25 mm or more and 10 mm or less. The area of ​​the emitting surface of the light source 123 when viewed along direction D1 is, for example, 0.25 mm × 0.25 mm to 10 mm × 10 mm.

[0097] The size of the incident end 143a in the plane encompassing both directions D2 and D3 can be the same as the size of the emitting surface of the light source 123 in the plane encompassing both directions D2 and D3, but is preferably moderately larger than the size of the emitting surface of the light source 123 in the plane encompassing both directions D2 and D3. At the incident end 143a, the dimension of the opening for the red light LR incident along the long side parallel to the D2 direction is 1 mm or more and 3 mm or less, preferably about 2 mm.

[0098] The emitting end 143b corresponds to the third emitting end, extends parallel to the plane encompassing directions D2 and D3, and is larger than the incident end 143a. The shape of the emitting end 143b when viewed from direction D1 is the same as the modulation surface of the light modulation element 183 when viewed from the same direction, for example, it is rectangular. The size of the emitting end 143b within the plane encompassing directions D2 and D3 is equal to the size of the modulation surface of the light modulation element 183 within the plane encompassing directions D2 and D3. At the emitting end 143b, the size of the opening for emitting red light LR along the long side parallel to direction D2 is 14 mm or more and 16 mm or less, preferably about 15 mm. The size of the long side direction of the modulation surface of the light modulation element 183, i.e., the direction D2, is, for example, 15 mm. Furthermore, the size of the modulation surface of the optical modulation element 183 can be appropriately selected, for example, from 6.48mm × 11.52mm for the 0.52-inch type to 19.44mm × 34.56mm for the 1.5-inch type.

[0099] The side surface 143s and the reflecting surface 143r connect the periphery of the incident end 143a and the periphery of the emission end 143b in the D1 direction.

[0100] Red light LR emitted from light source 123 enters light guide element 143 from incident end 143a. Within light guide element 143, the internal space enclosed by incident end 143a, emission end 143b, and reflecting surface 143r is the region where red light LR propagates. The size of the internal space enclosed by incident end 143a, emission end 143b, and reflecting surface 143r within the plane encompassing directions D2 and D3 increases as the light travels from the +D1 side to the -D1 side in direction D1. Furthermore, as the light travels from the +D1 side to the -D1 side, the shape of the internal space enclosed by incident end 143a, emission end 143b, and reflecting surface 143r within the plane encompassing directions D2 and D3 changes from the shape of the emitting surface of light source 123 when viewed from direction D1 to the shape of the modulation surface of light modulation element 183.

[0101] The side surface 143s of the light guide element 143 and the reflecting surface 143r provided on the side surface 143s, as described later, form a predetermined angle with respect to the imaginary line perpendicular to the incident end 143a and the optical axis. As it moves from the +D1 side to the -D1 side, it moves away from the imaginary line in the plane including the D2 and D3 directions. The red light LR incident on the light guide element 143 propagates from the +D1 side to the -D1 side in the internal space surrounded by the incident end 143a, the exit end 143b, and the reflecting surface 143r.

[0102] The modulation surface of the light modulation element 183, when viewed along the D1 direction, is rectangular, and the emitting surface of the light source 123, when viewed along the D1 direction, is also rectangular. The angle α formed by the rectangular side 143s (parallel to the D3 direction) and the reflecting surface 143r with respect to the aforementioned imaginary line and optical axis is preferably in the range of 7° or more and 22° or less. The angle β formed by the rectangular side 143s (parallel to the D2 direction) and the reflecting surface 143r with respect to the aforementioned imaginary line and optical axis is preferably in the range of 14° or more and 36° or less. The preferred ranges of angles α and β are appropriately set through numerical simulations based on the structure of the red light emitting section 103 and ray tracing, in a manner that the reflective film 253 of the light guide element 143 has a desired spectral reflectivity, as described later.

[0103] A portion of the red light LR incident on the light guide element 143 forms an angle smaller than a predetermined angle with respect to the imaginary line and the optical axis, and does not incident on the reflecting surface 143r even once, but propagates directly from the incident end 143a to the exit end 143b. The remaining portion of the red light LR incident on the light guide element 143 forms an angle greater than a predetermined angle with respect to the imaginary line and the optical axis, and is incident on the reflecting surface 143r more than once from the incident end 143a, is reflected by the reflecting surface 143r, and reaches the exit end 143b. The path of the red light LR within the internal space surrounded by the incident end 143a, the exit end 143b, and the reflecting surface 143r varies depending on the incident angle towards the incident end 143a, resulting in multiple paths involving different numbers of reflections at the reflecting surface 143r.

[0104] The illuminance distribution of the red light LR propagating in the internal space surrounded by the incident end 143a, the emission end 143b, and the reflecting surface 143r is homogenized within the plane encompassing both the D2 and D3 directions. That is, the light guide element 143 homogenizes the illuminance distribution of the incident red light LR within the plane encompassing both the D2 and D3 directions. The red light LR with its illuminance distribution homogenized is emitted from the emission end 143b towards the -D1 side.

[0105] Light guide element 143, like light guide elements 141 and 142, is a reflector and is formed as a hollow component. When viewed along the D1 direction, the +D1 side end of 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, for example, it is formed as a rectangle. The -D1 side end of light guide element 143 has the same shape and size as the emitting end 143b and the modulation surface of the light modulation element 183, for example, it is formed as a rectangle of a different size than the +D1 side end.

[0106] The reflector of the light guide element 143 is composed of four plate-shaped components 243 and a reflective film 253. The four plate-shaped components 243 correspond to the third substrate. They are formed by connecting the legs of the four trapezoidal plate-shaped components 243 to each other. The width, i.e., the dimension, of the side of the four plate-shaped components 243 corresponding to the upper base (+D1 side) parallel to the D2 or D3 direction is set according to the size of the incident end 143a and the emitting surface of the light source 123 in the D2 or D3 direction. The width, i.e., the dimension, of the side of the four plate-shaped components 243 corresponding to the lower base (-D1 side) parallel to the D2 or D3 direction is set according to the size of the emitting end 143b and the modulation surface of the light modulation element 183 in the D2 or D3 direction.

[0107] Taking into account the size of the light source 123, the width of the end 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, preferably 2 mm. The width of the end 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, preferably 15 mm. The length of the plate-shaped member 243 in the D1 direction from the incident end 143a to the emission end 143b is 5 mm or more and 25 mm or less. The shape of the light guide element 143 is the same as the shape of the light guide elements 141 and 142.

[0108] The material of plate-shaped component 243 includes at least one of Al, Ag, and glass, i.e., SiO2, and is preferably the same as the material of plate-shaped components 241 and 242.

[0109] Four plate-shaped components 243 are cut from a base material in a trapezoidal shape. A reflective film 253 is formed on one surface of a plate-shaped substrate made of the same material as the plate-shaped components 243. If, as described above, the material of the plate-shaped components 243 is the same as that of the plate-shaped components 241, and the structure of the reflective film 253 is the same as that of the reflective film 251, then the plate-shaped components 243 are cut from the base material 248 shared with the plate-shaped components 241. The edge of one leg of the first plate-shaped component 243 is connected to the edge of one leg of the second plate-shaped component 243. The edge of the other leg of the second plate-shaped component 243 is connected to the edge of one leg of the third plate-shaped component 243. The edge of the other leg of the third plate-shaped component 243 is connected to the edge of one leg of the fourth plate-shaped component 243. The edge of the fourth plate-shaped member 243, corresponding to the other side of the leg, is connected to the edge of the first plate-shaped member 243, corresponding to the other side of the leg.

[0110] Similarly, in the reflector of the light guide element 143, in order to improve the reflectivity of the red light LR incident from the incident end 143a to the light guide element 143 near the side 143s, a reflective film 253, made of a dielectric multilayer film or the like, is provided on the plate surface of the plate-shaped member constituting the reflector opposite to the side 143s, that is, on the plate surface facing the internal space of the reflector. A portion of the red light LR incident from the incident end 143a to the internal space of the reflector of the light guide element 143 is reflected by the reflective film 253 and travels towards the -D1 side.

[0111] The intensity of the red light LR emitted from the reflective film 253 after being reflected by the reflective film 253 sometimes depends on the incident angle of the red light LR incident on the reflective film 253. When the reflective film 253 is composed of a dielectric multilayer film, the incident angle dependence of the intensity of the red light LR emitted from the reflective film 253 varies, for example, depending on 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. When the reflective film 253 is composed of a metal film, for example, the incident angle dependence of the intensity of the red light LR emitted from the reflective film 253 varies, for example, depending on parameters such as the density of metal particles.

[0112] The reflective film 253 of the light guide element 143 has the same spectral reflectivity as the reflective film 251 of the light guide element 141 and the reflective film 252 of the light guide element 142. Specifically, similar to reflective films 251 and 252, the wavelength with the highest reflectivity in the visible band of the reflective film 253 is a wavelength in the green band, preferably in the range of 500 nm or more and 560 nm or less, more preferably 555 nm. The spectral reflectivity of the reflective film 253 in the visible band is 80% or more and 100% or less, preferably 85% or more and 100% or less, more preferably 90% or more and 100% or less.

[0113] During the manufacturing process of the reflective film 253, manufacturing errors such as those affecting the parameters of the dielectric multilayer film sometimes occur. For example, if thickness errors occur on the surfaces of the low-refractive-index and high-refractive-index layers constituting the reflective film 253, the spectral reflectance of the manufactured dielectric multilayer film may have the same distribution as the intended spectral reflectance, but sometimes it may deviate from the intended spectral reflectance distribution by several nm. Furthermore, even if the thicknesses of the low-refractive-index and high-refractive-index layers constituting the reflective film 253 are accurate and uniform, the spectral reflectance of the manufactured dielectric multilayer film may sometimes deviate from the intended spectral reflectance by a few percent due to the inclusion or amount of impurities. Even if manufacturing errors occur in the dielectric multilayer film of the reflective film 253, the wavelength difference between the wavelength of maximum reflectance in the spectral reflectance of the reflective film 253 and the wavelength of maximum reflectance in the spectral reflectance of the reflective films 251 and 252 is at least 5 nm or less, and preferably 3 nm or less. The difference between the maximum reflectance of the reflective film 253 and the maximum reflectance of the reflective films 251 and 252 is at least 3%. Within this range, it can be said that the reflective film 253 has the same reflective reflectance as the reflective films 251 and 252.

[0114] In the spectral reflectivity of the reflective film 253, the wavelength with the highest reflectivity is also the wavelength with the highest human visual sensitivity, thereby improving the visibility of the image projected by the projector 301. By adjusting the parameters of the dielectric multilayer film and the metal film constituting the reflective film 253, the spectral reflectivity of the reflective film 253 and the wavelength with the highest reflectivity can be effectively controlled.

[0115] As described above, for example, when the angle α is in the range of 7° to 22° and the angle β is in the range of 14° to 36°, the reflective film 253 is designed such that the incident angle of the red light LR, which has the highest intensity emitted from the reflective surface 143r and the reflective film 253, is in the range of 60° to 90°, and the parameters of the dielectric multilayer film are appropriately determined. The relationship between the incident angle of the red light LR incident on the reflective film 253 and the intensity of the red light LR emitted from the reflective film 253 is also obtained through numerical simulation based on the structure of the red light emitting section 103 and ray tracing.

[0116] The parallelizing element 163 is disposed in the optical path of the red light LR emitted from the light guide element 143, and is positioned closer to the -D1 side than the light guide element 143 and overlapping with the light guide element 143 in the D2 and D3 directions. The parallelizing element 163 parallelizes the red light LR emitted from the light guide element 143 along the D1 direction.

[0117] The parallelizing element 163 is, for example, a plano-convex lens, having: an incident surface composed of a flat surface perpendicular to the D1 direction; and an exit surface composed 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 parallelizing element 163 is located at least on the +D1 side of the parallelizing element 163, and on the opposite side to the -D1 side from which the red light LR is emitted from the parallelizing element 163, and further on the +D1 side of the light guide element 143. The incident surface of the parallelizing element 163 is in contact with the exit end 143b of the light guide element 143. By connecting the parallelizing element 163 to the exit end 143b, the red light LR emitted from the exit end 143b of the light guide element 143 is captured by the parallelizing element 163 to the maximum extent, and the loss of the red light LR can be suppressed. However, the parallelizing element 163 can also be an optical lens other than a plano-convex lens that can parallelize the incident red light LR, and can also be configured at an appropriate distance from the light guide element 143 in the D1 direction.

[0118] The incident-side polarizing element 173 is disposed in the optical path of the red light LR emitted from the parallelizing element 163, and is positioned closer to the -D1 side than the parallelizing element 163 and overlaps with the parallelizing element 163 in the D2 and D3 directions. The incident-side polarizing element 173 is connected to the optical modulation element 183, for example, from the +D1 side, but it can also be disposed at a suitable distance from the optical modulation element 183 in the D1 direction.

[0119] The incident-side polarizing element 173 causes a predetermined polarized light in the red light LR emitted from the parallelizing element 163 to exit along the D1 direction toward the -D1 side. The predetermined polarized light is, for example, S-polarized light. The incident-side polarizing element 173 is, for example, a reflective or absorptive polarizing plate having a plate surface parallel to a plane containing both the D2 and D3 directions. The incident-side polarizing element 173 causes a portion of the incident red light LR containing the predetermined polarized light to pass through toward the -D1 side, and causes another portion of the red light LR to be reflected or absorbed toward the +D1 side. Furthermore, when it is desirable to suppress return light and stray light toward the light source 123, the incident-side polarizing element 173 is preferably an absorptive polarizing plate.

[0120] The red light LR emitted from light source 123 contains at least P-polarized light and S-polarized light, such as randomly polarized light. The S-polarized component of the red light LR emitted from light source 123 passes sequentially through light guide element 143 and parallelization element 163 as described above, passes through incident-side polarization element 173, and exits at a position closer to the -D1 side than incident-side polarization element 173. The P-polarized component of the red light LR passes sequentially through light guide element 143 and parallelization element 163 in the same manner as the S-polarized component, but is reflected at the incident surface of incident-side polarization element 173 and exits at a position closer to the +D1 side than incident-side polarization element 173, or is absorbed by incident-side polarization element 173.

[0121] An optical modulation element 183 is disposed in the optical path of the red light LR emitted from the incident-side polarizing element 173, and is positioned closer to the incident-side polarizing element 173 on the -D1 side and overlapping with the incident-side polarizing element 173 in the D2 and D3 directions. The optical modulation element 183 is equivalent to a third optical modulation element, which modulates the red light LR emitted from the incident-side polarizing element 173 based on image information transmitted by an image forming apparatus such as a computer (not shown). This image forming apparatus is externally connected to the optical modulation element 183.

[0122] The light modulation element 183 is, for example, a transmissive liquid crystal panel. The liquid crystal panel constituting the light modulation element 183 has multiple pixels (not shown). Each pixel has a switching element. The switching element is, for example, a TFT. An electrical signal is supplied to the switching element of each pixel, and this electrical signal corresponds to the brightness of red light at the relative position of each pixel in the modulation surface of the light modulation element 183 in the image projected by the projector 301. Each pixel modulates the vibration direction of the red light LR incident from the incident-side polarizing element 173 according to the operation of the switching element corresponding to the aforementioned electrical signal, 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 along the D1 direction toward the -D1 side.

[0123] An emission-side polarizing element 177 is disposed in the optical path of the image light IR emitted from the optical modulation element 183, and is positioned closer to the -D1 side than the optical modulation element 183, overlapping the optical modulation element 183 in the D2 and D3 directions. The emission-side polarizing element 177 is connected to the optical modulation element 183, for example, from the -D1 side, but it can also be disposed with a suitable distance between it and the optical modulation element 183 in the D1 direction. The emission-side polarizing element 177 causes a predetermined polarized light in the image light IR emitted from the optical modulation element 183 to be emitted towards the -D1 side along the D1 direction. The predetermined polarized light is, for example, P-polarized light.

[0124] The exit-side polarizing element 177 is, for example, a reflective or absorptive polarizing plate having a plate surface parallel to the plane containing the D2 and D3 directions. The exit-side polarizing element 177 allows a portion of the incident image light IR containing a predetermined polarization to pass through to the -D1 side, and reflects or absorbs another portion of the image light IR towards the +D1 side. Furthermore, when it is desirable to suppress return light and stray light from the light modulation element 183, the exit-side polarizing element 177 is preferably an absorptive polarizing plate.

[0125] The light combining element 200 is disposed in the region where the optical paths of the blue image light IB emitted from the emission-side polarizing element 175, the green image light IG emitted from the emission-side polarizing element 176, and the red image light IR emitted from the emission-side polarizing element 177 intersect. The light combining element 200 combines the image lights IB, IG, and IR emitted from the emission-side polarizing elements 175, 176, and 177 and emits them along the D2 direction toward the +D2 side.

[0126] The light-combining element 200 is, for example, a cross-shaped dichroic prism 210. The cross-shaped 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 the surfaces encompassing directions D2 and D3, and overlap with each other in directions D2 and D3. The incident surface 210d and the exit surface 210b are parallel to the surfaces encompassing directions D1 and D3, and overlap with each other in directions D1 and D3.

[0127] When viewed along the D3 direction, reflective film 211 is configured to move from the +D2 side to the -D2 side as it moves from the -D1 side to the +D1 side. When viewed along the D3 direction, reflective film 212 is configured to move from the -D2 side to the +D2 side as it moves from the -D1 side to the +D1 side. Reflective films 211 and 212 overlap with incident surfaces 210c and 210e in the D2 direction and with exit surface 210b and incident surface 210d in the D3 direction. Reflective film 212 reflects blue light and transmits green and red light. Reflective film 211 reflects red light and transmits blue and green light.

[0128] When viewed from the D3 direction, the dichroic cross prism 210 is constructed by attaching four right-angled prisms together at right-angled structural surfaces, aligning their right-angled vertices with the center of the light-combining element 200. The four right-angled prisms of the dichroic cross prism 210 are formed of a transparent material that allows visible light to pass through. The reflective film 211 is disposed on the right-angled structural surfaces of the four right-angled prisms, and as described above, moves from the +D2 side to the -D2 side as it moves from the -D1 side to the +D1 side; it is, for example, made of a dielectric multilayer film. The reflective film 212 is disposed on the right-angled structural surfaces of the four right-angled prisms, and as described above, moves from the -D2 side to the +D2 side as it moves from the -D1 side to the +D1 side.

[0129] The p-polarized blue image light IB emitted from the exiting polarizing element 175 enters the interior of the cross dichroic prism 210 along the D1 direction from the incident surface 210c towards the +D1 side. It passes through the reflective film 211, is reflected by the reflective film 212, and travels towards the +D2 side. The p-polarized green image light IG emitted from the exiting polarizing element 176 enters the interior of the cross dichroic prism 210 along the D2 direction from the incident surface 210d towards the +D2 side. It passes through the reflective films 211 and 212 and travels straight towards the +D2 side. The p-polarized red image light IR emitted from the exiting polarizing element 177 enters the interior of the cross dichroic prism 210 along the D1 direction from the incident surface 210e towards the -D1 side. It passes through the reflective film 212, is reflected by the reflective film 211, and travels towards the +D2 side. The image light IB, IG, and IR emitted from the reflective films 211 and 212 of the dichroic prism 210 toward the +D2 side are combined to generate a full-color image light IM. The full-color image light IM is emitted from the exit surface 210b along the D2 direction toward the +D2 side from the dichroic prism 210.

[0130] The projection optical system 250 is positioned in 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 the screen SCR located on the +D2 side, and magnifies and displays the image sent from the image forming apparatus to the light modulation elements 181, 182, and 183 on the screen SCR.

[0131] The projection optical system 250 is, for example, composed of one or more optical lenses arranged along the D2 direction. The optical lenses include, for example, plano-convex lenses, plano-concave lenses, biconvex lenses, biconcave lenses, concave-convex lenses, aspherical lenses, freeform lenses, etc.

[0132] The projector 301 of this 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 guide element (second light guide element) 142, a light modulation element (first light modulation element) 181, a light modulation element (second light modulation element) 182, a light combining element 200, and a projection optical system 250. The light source 121 emits blue light (first light) LB in the blue band (first band). The light source 122 emits green light (second light) LG in the green band (second band), which is different from the blue band. The light guide element 141 has an incident end (first incident end) 141a, to which the blue light LB emitted from the light source 121 is incident; and an exit end (first exit end) 141b, which emits blue light LB. The light guide element 141 homogenizes the illuminance of the blue light LB within a plane encompassing directions D2 and D3. The light guide element 142 has an incident end (second incident end) 142a, to which green light LG emitted from the light source 122 is incident; and an exit end (second exit end) 142b, which emits green light LG. The light guide element 142 homogenizes the illuminance of the green light LG within a plane encompassing directions D1 and D3. The light modulation element 181 modulates the blue light LB emitted from the light guide element 141 based on image information. The light modulation element 182 modulates the green light LG emitted from the light guide element 142 based on image information. The light combining element 200 combines the image light (first light) IB emitted from the light modulation element 181 and the image light (second light) IG emitted from the light modulation element 182 and emits them. The projection optical system 250 projects image light (light) IM emitted from the light combining element 200. In the projector 301 of this embodiment, the spectral reflectivity of the light guide element 142 is the same as that of the light guide element 141.

[0133] In the projector 301 of this embodiment, two colors of light emitted from light sources 121 and 122, namely blue light LB and green light LG, are directly converted into image light IB and IG by light modulation elements 181 and 182. The image light IB and IG are then combined by light combining element 200 and projected onto the screen SCR. In conventional projectors, white light is generated, and the white light is separated into blue light, green light, etc., by a color separating element or a color separating optical system. Each color light is converted into image light by a light modulation element, and the image light is combined by a light combining element and projected. In contrast, in the projector 301 of this embodiment, the color combining element, color combining optical system, color separating element, and color separating optical system for separating the light into each color may not be provided in the front stage of the light modulation element corresponding to each color light. Therefore, compared with conventional projectors, the projector 301 of this embodiment can reduce the number of components and devices and achieve a larger size. According to the projector 301 of this embodiment, compared with conventional projectors, miniaturization can be achieved.

[0134] The spectral reflectivity of the light guide element 141 includes both of the following: spectral reflectivity that is substantially independent of the spectral reflectivity of the plate member 241 and is solely caused by the spectral reflectivity of the reflective film 251, as in this embodiment; and spectral reflectivity caused by the spectral reflectivity of both the plate member 241 and the reflective film 251, where the transmittance of blue light LB in the reflective film 251 is adjusted. In the latter case, where the transmittance of blue light LB in the reflective film 251 is adjusted, for example, the parameters of the dielectric multilayer film constituting the reflective film 251 are adjusted, and the spectral reflectivity of the plate member 241 is corrected using the spectral reflectivity of the reflective film 251 according to the amount of parameter adjustment. Similarly, the spectral reflectivity of the light guide element 142 includes both of the following: spectral reflectivity that is substantially independent of the spectral reflectivity of the plate member 242 and is solely caused by the spectral reflectivity of the reflective film 252, as in this embodiment; and spectral reflectivity caused by the spectral reflectivity of the plate member 242 and the reflective film 252, with the transmittance of green light LG in the reflective film 252 adjusted. The fact that the spectral reflectivity of the light guide element 142 is the same as that of the light guide element 141 means that, even considering manufacturing errors of the reflective films 251 and 252, the wavelength difference between the wavelength of maximum reflectivity in the spectral reflectivity of the light guide element 141 and the wavelength of maximum reflectivity in the spectral reflectivity of the light guide element 142 is 5 nm or less, and the difference between the maximum reflectivity in the spectral reflectivity of the light guide element 141 and the maximum reflectivity in the spectral reflectivity of the light guide element 142 is 3% or less.

[0135] In the projector 301 of this embodiment, if the spectral reflectivity of the reflective film 251 of the light guide element 141 and the spectral reflectivity of the reflective film 252 of the light guide element 142 are the same, then a common reflective film can be disposed on the plate surface of the plate member 241 of the light guide element 141 facing the internal space SP141 and on the plate surface of the plate member 242 of the light guide element 142 facing the internal space SP142. According to the projector 301 of this embodiment, the utilization efficiency of blue light LB and green light LG emitted from the light guide elements 141 and 142, the illuminance ratio in the screen SCR, and other optical characteristics can be optimized, and the manufacturing time, labor, and manufacturing cost of the reflective films 251 and 252 can be reduced.

[0136] The projector 301 of this embodiment further includes a light source (third light source) 123, a light guide element (third light guide element) 143, and a light modulation element (first light modulation element) 181. The light source 123 emits red light (third light) LR in a red band (third band) that is different from the blue and green bands. The light guide element 143 has an incident end (third incident end) 143a, into which the red light LR emitted from the light source 123 is incident; and an exit end (third exit end) 143b, into which the red light LR is emitted. The light guide element 143 homogenizes the illuminance of the red light LR in a plane including the D1 and D3 directions. The light modulation element 183 modulates the red light LR emitted from the light guide element 143 based on image information. The light combining element 200 further combines the image light (third light) IR emitted from the light modulation element 183 with the image light IB and IG and emits them. In the projector 301 of this embodiment, the spectral reflectivity of the light guide element 143 is the same as that of the light guide element 141 and the light guide element 142.

[0137] In the projector 301 of this embodiment, the blue light LB, green light LG, and red light LR emitted from the light sources 121, 122, and 123 are directly converted into image light IB, IG, and IR by the light modulation elements 181, 182, and 183. The image light IB, IG, and IR are then combined by the light combining element 200 to project a full-color image light IM. In the projector 301 of this embodiment, the color combining element, color combining optical system, color separating element, and color separating optical system for separating the light into its respective colors may not be provided in the pre-stage of the light modulation element corresponding to the three colors. Therefore, compared with conventional projectors, the projector 301 of this embodiment can further reduce the number of components and devices and achieve a larger size. The three-panel projector 301 of this embodiment can achieve miniaturization compared with conventional projectors.

[0138] The spectral reflectivity of the light guide element 143 includes both of the following: spectral reflectivity that is substantially independent of the spectral reflectivity of the plate member 243 and is solely caused by the spectral reflectivity of the reflective film 253, as in this embodiment; and spectral reflectivity caused by the spectral reflectivity of the plate member 243 and the reflective film 253, with the transmittance of red light LR in the reflective film 253 adjusted. The fact that the spectral reflectivity of the light guide element 143 is the same as that of the light guide elements 141 and 142 means that, even considering manufacturing errors of the reflective film 253, the wavelength difference between the wavelength of maximum reflectivity in the spectral reflectivity of the light guide element 143 and the wavelength of maximum reflectivity in the spectral reflectivity of the light guide elements 141 and 142 is less than 5 nm, and the difference between the maximum reflectivity in the spectral reflectivity of the light guide element 143 and the maximum reflectivity in the spectral reflectivity of the light guide elements 141 and 142 is less than 3%.

[0139] In the projector 301 of this embodiment, if the spectral reflectivity of the reflective film 253 of the light guide element 143 is the same as that of the reflective films 251 and 252, then a reflective film common to the plate surface of the plate-shaped member 243 of the light guide element 143 facing the internal space, and the plate surface of the plate-shaped member 241 of the light guide element 141 facing the internal space SP141, and the plate surface of the plate-shaped member 242 of the light guide element 142 facing the internal space SP142, can be arranged. According to the projector 301 of this embodiment, the utilization efficiency of blue light LB, green light LG, and red light LR emitted from the light guide elements 141, 142, and 143, the illuminance ratio in the screen SCR, and other optical characteristics can be optimized, and the manufacturing time, labor, and manufacturing cost of the reflective films 251, 252, and 253 can be further reduced.

[0140] In the projector 301 of this embodiment, the first light is blue light LB. The second light is green light LG. The third light is red light LR. The projector 301 of this embodiment can generate and project image light IM with high color reproducibility.

[0141] In the projector 301 of this embodiment, the first band contains 467 nm. The second band contains 532 nm. The third band contains 630 nm. In the projector 301 of this embodiment, the first, second, and third bands contain 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 color standard compliance.

[0142] In the projector 301 of this embodiment, the wavelength (band) with the highest reflectivity among the light guide elements 141, 142, and 143 includes 555nm.

[0143] In the projector 301 of this embodiment, the wavelength with the highest reflectivity among the light guide elements 141, 142, 143 and the reflective films 251, 252, 253 is consistent with the wavelength with the highest human visual sensitivity, thus improving the visibility of the projected image.

[0144] In the projector 301 of this embodiment, the light guide element 141 includes multiple plate-shaped members (first substrates) 241 having a reflective film (first reflective film) 251 that reflects blue light LB, for example, consisting of four plate-shaped members 241A, 241B, 241C, and 241D. The light guide element 142 includes multiple plate-shaped members (second substrates) 242 having a reflective film (second reflective film) 252 that reflects green light LG, for example, consisting of four plate-shaped members 242. The light guide element 143 includes multiple plate-shaped members (third substrates) 243 having a reflective film (third reflective film) 253 that reflects red light LR, for example, consisting of four plate-shaped members 243. The spectral reflectivity of the reflective film 251 of the light guide element 141, the spectral reflectivity of the reflective film 252 of the light guide element 142, and the spectral reflectivity of the reflective film 253 of the light guide element 143 are the same.

[0145] In the projector 301 of this embodiment, the reflective films 251, 252, and 253 are formed with a common reflective structure such as a dielectric multilayer film. Preferably, components made of a common material are used as elements constituting the light guide elements 141, 142, and 143, namely, plate-shaped components 241, 242, and 243. According to the projector 301 of this embodiment, the manufacturing time, labor, and manufacturing cost of the light guide elements 141, 142, and 143 can be reduced.

[0146] In the projector 301 of this embodiment, the light guide elements 141, 142, and 143 include at least one of Al, Ag, and glass.

[0147] Al and Ag have high reflectivity of approximately 90% or more in the visible band, exhibiting excellent spectral reflectivity as plate-shaped components of light guide elements 141, 142, and 143. In the projector 301 of this embodiment, if Al or Ag is used as the material for the plate-shaped components 241, 242, and 243, the spectral reflectivity of the light guide elements 141, 142, and 143 can be corrected based on the spectral reflectivity of Al or Ag, thereby easily achieving a common spectral reflectivity in the visible band among the light guide elements 141, 142, and 143. Furthermore, Al and Ag have excellent heat dissipation and heat resistance, thus enabling the construction of light guide elements 141, 142, and 143 possessing these superior properties. Glass is easy to form and has high surface precision. In the projector 301 of this embodiment, if glass is used as the material for the plate-shaped components 241, 242, and 243, the shape accuracy of the light guide elements 141, 142, and 143 is improved, ensuring the characteristics of the reflective films 251, 252, and 253. According to the projector 301 of this embodiment, the light guide elements 141, 142, and 143 are constructed with excellent heat dissipation and heat resistance, making the design of the reflective films 251, 252, and 253 easier and ensuring optical characteristics, including spectral reflectivity.

[0148] In the projector 301 of this embodiment, the light guide elements 141, 142, and 143 have the same shape.

[0149] If the light guide elements 141, 142, and 143 have the same shape, the plate-shaped components 241, 242, and 243 are made of the same material, and the reflective films 251, 252, and 253 are made of the same material and have the same structure, then the light guide elements 141, 142, and 143 can be constructed from the same materials and components. According to the projector 301 of this embodiment, the manufacturing time, labor, and manufacturing cost of the light guide elements 141, 142, and 143 can be reduced.

[0150] In the projector 301 of this embodiment, the cross-sectional shape of the light guide elements 141 and 143 perpendicular to the optical axis and the D1 direction is rectangular, and the cross-sectional shape of the light guide element 142 perpendicular to the optical axis and the D2 direction is rectangular.

[0151] In the projector 301 of this embodiment, blue light LB, green light LG, and red light LR, which are rectangular in shape and have uniform illumination in a plane perpendicular to the optical axis of the colored light, can be easily generated by the light guide elements 141, 142, and 143. According to the projector 301 of this embodiment, rectangular colored light corresponding to the modulation surfaces of the light modulation elements 181, 182, and 183 can be easily generated.

[0152] In the projector 301 of this embodiment, the cross-sectional area of ​​the emission end 141b of the light guide element 141, including directions D2 and D3, is larger than the cross-sectional area of ​​the incident end 141a of the light guide element 141, including directions of the same. The cross-sectional area of ​​the emission end 142b of the light guide element 142, including directions D1 and D3, is larger than the cross-sectional area of ​​the incident end 142a of the light guide element 142, including directions of the same. The cross-sectional area of ​​the emission end 143b of the light guide element 143, including directions D2 and D3, is larger than the cross-sectional area of ​​the incident end 143a of the light guide element 143, including directions of the same.

[0153] In the projector 301 of this embodiment, before light enters from the incident ends 141a, 142a, and 143a of the light guide elements 141, 142, and 143 and exits from the emission ends 141b, 142b, and 143b, the illuminance distribution of blue light LB, green light LG, and red light LR is homogenized, and the illumination area of ​​each color light is expanded. According to the projector 301 of this embodiment, the illuminance distribution of each of the blue light LB, green light LG, and red light LR emitted from the light sources 121, 122, and 123 can be homogenized on a plane perpendicular to the optical axis, and the size of the blue light LB, green light LG, and red light LR on the plane perpendicular to the optical axis can be easily expanded corresponding to the modulation surfaces of the light modulation elements 181, 182, and 183.

[0154] In the projector 301 of this embodiment, the distance in the D1 direction from the incident end 141a to the emission 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 emission 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 emission end 143b of the light guide element 143 is 5 mm or more and 25 mm or less.

[0155] In the projector 301 of this embodiment, the lengths of the light guide elements 141, 142, and 143 along the optical axis of the colored light are appropriately set. Therefore, the illuminance distribution on the planes perpendicular to the optical axis of the blue light LB, green light LG, and red light LR guided by the light guide elements 141, 142, and 143 can be made more uniform, and the illuminance distribution on the planes perpendicular to the optical axis of the blue light LB, green light LG, and red light LR can be expanded.

[0156] In the projector 301 of this embodiment, the incident end 141a of the light guide element 141 has a width (size) d1 in the D2 direction along the long side of the opening API 141 for incident blue light LB. The width d1 of the incident end 141a is 1 mm or more and 3 mm or less. The emitting end 141b of the light guide element 141 has a width (size) d2 in the D2 direction along the long side of the opening APE 141 for emitting blue light LB. The width d2 of the emitting 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 (size) in the D1 direction along the long side of the opening API 142 for incident green light LG. The width of the incident end 142a in the D1 direction is 1 mm or more and 3 mm or less. The emitting end 142b of the light guide element 142 has a width (size) in the D1 direction along the long side of the opening APE 142 for emitting green light LG. The width of the emitting end 142b in the D1 direction is 14 mm or more and 16 mm or less. The incident end 143a of the light guide element 143 has a width (dimension) in the D2 direction along the long side of the opening for incident red light LR. The width of the incident end 143a in the D2 direction is 1 mm or more and 3 mm or less. The emitting end 143b of the light guide element 143 has a width (dimension) in the D2 direction along the long side of the opening for emitting red light LR. The width of the emitting end 143b in the D2 direction is 14 mm or more and 16 mm or less.

[0157] In the projector 301 of this embodiment, the widths of the incident end 141a and the emission end 141b of the light guide element 141 are appropriately set. Similarly, the widths of the incident end 142a and the emission end 142b of the light guide element 142 are appropriately set, and the widths of the incident end 143a and the emission end 143b of the light guide element 143 are appropriately set. According to the projector 301 of this embodiment, the extraction efficiency of blue light LB in the light guide element 141 and the efficiency of illuminance distribution uniformity can be improved. Furthermore, according to the projector 301 of this embodiment, the extraction efficiency of green light LG in the light guide element 142 and the efficiency of illuminance distribution uniformity can be improved, and the extraction efficiency of red light LR in the light guide element 143 and the efficiency of illuminance distribution uniformity can be improved.

[0158] In the projector 301 of this embodiment, the tilt angle of the sides 141s, 142s, and 143s of the light guide elements 141, 142, and 143, including the short side, i.e., the angle α relative to the optical axis, is 7° or more and 22° or less. The tilt angle of the sides 141s, 142s, and 143s of the light guide elements 141, 142, and 143, including the long side, i.e., the angle β relative to the optical axis, is 14° or more and 36° or less.

[0159] In the projector 301 of this embodiment, blue light LB, green light LG, and red light LR are emitted from light sources 121, 122, and 123, and are incident radially into the interiors of light guide elements 141, 142, and 143 from incident ends 141a, 142a, and 143a at predetermined angles relative to the optical axis. According to the projector 301 of this embodiment, the loss of blue light LB, green light LG, and red light LR in the light guide elements 141, 142, and 143 can be minimized, and the utilization efficiency of blue light LB, green light LG, and red light LR can be improved. According to the projector 301 of this embodiment, the efficiency of homogenizing the illuminance distribution of blue light LB, green light LG, and red light LR in the light guide elements 141, 142, and 143 can be improved.

[0160] Furthermore, in the projector 301 of this embodiment, light sources 121 and 122 contain GaN-based semiconductor materials as light emitters. Light source 123 contains AlGaInP as a light emitter. Light source 122 has a phosphor 124 that emits green light LG. Light source 121, which emits blue light LB, and light source 123, which emits red light LR, do not have phosphors but instead have LEDs or LDs. Therefore, the luminous efficiency of the green light LG emitted from light source 122 is more likely to be lower than the luminous efficiency of the blue light LB emitted from light source 121 and the luminous efficiency of the red light LR emitted from light source 123. If the green band has the highest reflectivity among the spectral reflectivities of reflective films 251, 252, and 253, then even if the luminous efficiency of light source 122 is lower than that of light sources 121 and 123, the difference in reflectivity of the colored light in light guide elements 141, 142, and 143 can be used to correct the difference in luminous efficiency between the light sources, thus projecting an image light IM with high color reproducibility and good color balance and brightness.

[0161] However, due to material properties, the amount of red light LR emitted from the light source 123 containing AlGaInP is sometimes relatively less than the amount of blue light LB emitted from the light source 121 containing GaN-based semiconductor materials and the amount of green light LG emitted from the light source 122 containing GaN-based semiconductor materials. As a design modification example of the projector 301 in this embodiment, the band with the highest reflectivity among the spectral reflectivities of the light guide elements 141, 142, 143 and the reflective films 251, 252, 253 can also be the red band. According to the design modification example of the projector 301 in this embodiment, even if the luminous efficiency of red light LR in the light source 123 is lower than that of blue light LB in the light source 121 and green light LG in the light source 122, the difference in reflectivity of the colored light in the light guide elements 141, 142, 143 can be used to correct the difference in luminous efficiency between the light sources, and project an image light IM with high color reproducibility and good color balance and brightness.

[0162] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to these specific embodiments. Various modifications and alterations can be made within the scope of the spirit of the present invention as described in the claims.

[0163] For example, similar to the green light emitting section 102, the LEDs constituting the light sources 121 and 123 in the blue light emitting section 101 and the red light emitting section 103 may also have phosphors. These phosphors are excited by light from the LED body to emit blue light LB and red light LR, respectively. Conversely, the LEDs of the light source 122 in the green light emitting section 102 may not have phosphors 124, and the light source 122 may be composed of LEDs that directly emit green light LG. Furthermore, the polarization components transmitted by the incident-side polarizers arranged in the light paths of each color of light may be common components or may not be common components.

[0164] This is a summary of the disclosure.

[0165] The following is a summary published in this note.

[0166] Postscript 1

[0167] A projector comprising: a first light source emitting first light of a first wavelength band; a second light source emitting second light of a second wavelength band different from the first wavelength band; a first light guide element having a first incident end and a first exiting end, wherein the first light emitted from the first light source is incident on the first incident end, and the first exiting end emits the first light, the first light guide element homogenizing the in-plane illuminance of the first light; and a second light guide element having a second incident end and a second exiting end, wherein the second light emitted from the second light source is incident on the second incident end, and the second exiting end emits the second light, the first light guide element homogenizing the in-plane illuminance of the first light; and a second light guide element having a second incident end and a second exiting end, wherein the second light emitted from the second light source is incident on the second incident end, and the second exiting end emits the second light, the first light guide element homogenizing the in-plane illuminance of the first light; and a second light guide element having a first incident end and a second exiting end, wherein the first light emitted from the first light source is incident on the first ... source emitting first light of a first wavelength band different from the first wavelength band; a first light guide element having a first incident end and a second exiting end, wherein the first light emitted from the first light source is incident on the first incident end, and the second exiting end emits the second light, the first light source emitting first light of a first wavelength band different from the first wavelength band; a first light guide element having a first incident end and a second exiting end, wherein the first light emitted from the first light source is incident on the first incident end, and the second exiting end emits the second light, the first light source emitting first light of a first wavelength band different from The system comprises: 2 light guiding elements that homogenize the in-plane illuminance of the second light; a first light modulation element that modulates the first light emitted from the first light guiding element based on image information; a second light modulation element that modulates the second light emitted from the second light guiding element based on image information; a light combining element that combines the first light emitted from the first light modulation element and the second light emitted from the second light modulation element for emission; and a projection optical system that projects the light emitted from the light combining element, wherein the spectral reflectivity of the second light guiding element is the same as that of the first light guiding element.

[0168] According to the structure in Appendix 1, there is no need for optical components used to generate white light or optical components used to separate light according to each color. Therefore, the number of components is reduced, which can suppress the enlargement of 3-panel projectors and realize a small projector. According to the structure in Appendix 1, the manufacturing time, labor and manufacturing cost of the first light guide element and the second light guide element can be reduced.

[0169] Appendix 2

[0170] According to the projector described in Appendix 1, the projector further comprises: a third light source that emits third light of a third band different from the first and second bands; a third light guide element having a third incident end and a third exiting end, wherein the third light emitted from the third light source is incident on the third incident end and the third exiting end emits the third light, and the third light guide element homogenizes the in-plane illuminance of the third light; and a third light modulation element that modulates the third light emitted from the third light guide element based on image information, wherein the light combining element further combines the third light emitted from the third light modulation element and emits it, wherein the spectral reflectivity of the third light guide element is the same as that of the first and second light guide elements.

[0171] According to the structure in Appendix 2, the number of components is reduced, which can prevent the large size of 3-panel projectors and realize small projectors. According to the structure in Appendix 2, the manufacturing time, labor and manufacturing cost of the first light guide element, the second light guide element and the third light guide element can be reduced.

[0172] Appendix 3

[0173] According to the projector described in Appendix 2, the first light is blue light, the second light is green light, and the third light is red light.

[0174] Based on the structure in Appendix 3, it is possible to generate image light with high color reproducibility.

[0175] Appendix 4

[0176] According to the projector described in Appendix 3, the first band contains 467 nm, the second band contains 532 nm, and the third band contains 630 nm.

[0177] According to the structure in Appendix 4, since the first, second, and third bands contain the primary color wavelengths of BT.2020, which serve as representative color standards, they are able to meet color reproduction standards.

[0178] Appendix 5

[0179] According to the projector described in Appendix 4, the wavelength band with the highest reflectivity in the spectral reflectivity of the first light guide element includes 555 nm.

[0180] According to the structure in Appendix 5, the wavelength with the highest reflectivity in the spectral reflectivity of the first light guide element is consistent with the wavelength with the highest human visual sensitivity, which can improve the visibility of the projected image.

[0181] Appendix 6

[0182] The projector according to any one of Appendices 3 to 5, wherein the first light source and the second light source comprise gallium nitride-based semiconductor materials, the third light source comprises aluminum gallium indium phosphide, the red band is the wavelength with the highest reflectivity in the spectral reflectivity of the first light guide element, the red band is the wavelength with the highest reflectivity in the spectral reflectivity of the second light guide element, and the red band is the wavelength with the highest reflectivity in the spectral reflectivity of the third light guide element.

[0183] According to the structure in Appendix 6, even when the luminous efficiency of the third light in the third light source is lower than that of the first light in the first light source and the second light in the second light source, the color balance and brightness of the projected image light can still be improved.

[0184] Appendix 7

[0185] According to any one of Appendices 2 to 6, the projector comprises a first light guide element having a plurality of first substrates having a first reflective film that reflects the first light, a second light guide element having a plurality of second substrates having a second reflective film that reflects the second light, and a third light guide element having a plurality of third substrates having a third reflective film that reflects the third light, wherein the first reflective film, the second reflective film, and the third reflective film have the same spectral reflectivity.

[0186] According to the structure in Appendix 7, the components constituting the first light guide element, the second light guide element, and the third light guide element can be shared, thus making it easy to manufacture these light guide elements and reducing manufacturing costs.

[0187] Postscript 8

[0188] The projector according to any one of Appendices 1 to 7, wherein the first light guide element and the second light guide element comprise at least one of aluminum, silver, and glass.

[0189] According to the structure in Appendix 8, a first light guide element and a second light guide element with excellent heat dissipation and heat resistance are constructed, which makes the design of the first reflective film and the second reflective film easier and ensures optical properties including spectral reflectivity.

[0190] Postscript 9

[0191] The projector according to any one of Appendices 1 to 8, wherein the first light guide element and the second light guide element have the same shape.

[0192] According to the structure in Appendix 9, the first and second light guide elements are made of common materials and components, which can reduce manufacturing time, labor and manufacturing costs.

[0193] Postscript 10

[0194] According to the projector described in Appendix 9, the first light guide element has a rectangular cross-sectional shape, and the second light guide element has a rectangular cross-sectional shape.

[0195] According to the structure in Appendix 10, it is easy to generate a first light and a second light with a uniform illuminance distribution in a rectangular shape as illumination light.

[0196] Postscript 11

[0197] According to the projector described in Appendix 9 or 10, the cross-sectional area of ​​the first emission end is larger than the cross-sectional area of ​​the first incident end, and the cross-sectional area of ​​the second emission end is larger than the cross-sectional area of ​​the second incident end.

[0198] According to the structure in Appendix 11, the size of the irradiation area of ​​the first light emitted from the first light source is made to match the size of the modulation surface of the first light modulation element, which makes 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 is made to match the size of the modulation surface of the second light modulation element, which makes it easy to uniformize the illuminance distribution of the second light.

[0199] Postscript 12

[0200] The projector according to any one of Appendices 9 to 11, wherein the length from the first incident end to the first exit end is 5 mm or more and 25 mm or less.

[0201] According to the structure in Appendix 12, the illuminance distribution of the first light emitted from the first light source can be efficiently homogenized, the illuminance distribution of the second light emitted from the second light source can be efficiently homogenized, and the first and second lights can be expanded towards the emission side.

[0202] Postscript 13

[0203] According to the projector described in Appendix 12, the first incident end has a dimension along the long side of the opening through which the first light is incident, the dimension of the first incident end being 1 mm or more and 3 mm or less, and the first emitting end has a dimension along the long side of the opening through which the first light is emitted, the dimension of the first emitting end being 14 mm or more and 16 mm or less.

[0204] According to the structure in Appendix 13, the efficiency of taking in the first light into the first light guide element and the efficiency of homogenizing the first light can be improved, and the efficiency of taking in the second light into the second light guide element and the efficiency of homogenizing the second light can be improved.

[0205] Postscript 14

[0206] According to the projector described in Appendix 9, the tilt angle of the side including the short side of the first light guide element is 7° or more and 22° or less.

[0207] The tilt angle of the side including the long side of the first light guide element is more than 14° and less than 36°.

[0208] According to the structure in Appendix 14, the efficiency of taking in the first light into the first light guide element and the efficiency of homogenizing the first light can be improved, and the efficiency of taking in the second light into the second light guide element and the efficiency of homogenizing the second light can be improved.

Claims

1. A projector characterized by comprising: The projector comprises: a first light source that emits first light of a first wavelength band; a second light source that emits second light of a second wavelength band different from the first wavelength band; a first light guide element that has a first incident end to which the first light emitted from the first light source is incident and a first emission end that emits the first light; a second light guide element that has a second incident end to which the second light emitted from the second light source is incident and a second emission end that emits the second light; a first light modulation element that modulates the first light emitted from the first light guide element based on image information; a second light modulation element that modulates the second light emitted from the second light guide element based on the image information; a light synthesizing element that synthesizes the first light emitted from the first light modulation element and the second light emitted from the second light modulation element and emits the synthesized light; and a projection optical system that projects the light emitted from the light synthesizing element, the light reflectance of the second light guide element is the same as the light reflectance of the first light guide element.

2. The projector according to claim 1, further comprising: a third light source that emits third light of a third wavelength band different from the first wavelength band and the second wavelength band; a third light guide element that has a third incident end to which the third light emitted from the third light source is incident and a third emission end that emits the third light; and a third light modulation element that modulates the third light emitted from the third light guide element based on the image information, the light synthesizing element further synthesizes the third light emitted from the third light modulation element and emits the synthesized light, the light reflectance of the third light guide element is the same as the light reflectance of the first light guide element and the light reflectance of the second light guide element.

3. The projector according to claim 2, wherein the first light is blue light, the second light is green light, the third light is red light.

4. The projector according to claim 3, wherein the first wavelength band includes 467 nm, the second wavelength band includes 532 nm, the third wavelength band includes 630 nm.

5. The projector according to claim 4, wherein a wavelength band having the highest reflectance in the light reflectance of the first light guide element includes 555 nm.

6. The projector according to claim 3 or 4, wherein the first light source and the second light source include a gallium nitride-based semiconductor material, the third light source includes an aluminum gallium indium phosphide, a wavelength band having the highest reflectance in the light reflectance of the first light guide element is a red wavelength band, a wavelength band having the highest reflectance in the light reflectance of the second light guide element is a red wavelength band, a wavelength band having the highest reflectance in the light reflectance of the third light guide element is a red wavelength band.

7. The projector according to any one of claims 2 to 5, wherein ​ ​ The first light guide element has a plurality of first substrates having a first reflecting film that reflects the first light, The second light guide element has a plurality of second substrates having a second reflecting film that reflects the second light, The third light guide element has a plurality of third substrates having a third reflecting film that reflects the third light, The first reflecting film, the second reflecting film, and the third reflecting film have the same spectral reflectance.

8. The projector according to any one of claims 1 to 5, wherein The first light guide element and the second light guide element include at least any one of aluminum, silver, and glass.

9. The projector according to any one of claims 1 to 5, wherein The first light guide element and the second light guide element have the same shape.

10. The projector according to claim 9, wherein The first light guide element has a rectangular cross-sectional shape, The second light guide element has a rectangular cross-sectional shape.

11. The projector according to claim 9, wherein The first exit end has a larger cross-sectional area than the first entrance end, The second exit end has a larger cross-sectional area than the second entrance end.

12. The projector according to claim 9, wherein A length from the first entrance end to the first exit end is 5 mm or more and 25 mm or less.

13. The projector according to claim 12, wherein The first entrance end has a dimension along a long side of an opening through which the first light is incident, The dimension of the first entrance 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 exit end is 14 mm or more and 16 mm or less.

14. The projector according to claim 9, wherein An inclination angle of a side surface of the first light guide element including a short side is 7° or more and 22° or less, and an inclination angle of a side surface of the first light guide element including a long side is 14° or more and 36° or less.

Images