Projector

Abstract

Provided is a projector. In a projector, irradiation of useless light to a light modulation element is suppressed, and color reproducibility of a projected image is improved. A projector according to an embodiment includes: a first light source that emits first light of a first wavelength band and second light of a second wavelength band; a first light guide element that has a first substrate and a first reflective film disposed on the first substrate, and that has a first incident end to which the first light and the second light emitted from the first light source are incident, and a first emission end that emits the first light; a first light modulation element that modulates the light of the first wavelength band emitted from the first light guide element on the basis of image information; and a projection optical system that projects the light emitted from the first light modulation element. The reflectance of the first light guide element to the second light is lower than the reflectance of the first light.

Description

Technical Field

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

[0002] Previously, projectors were known to include: a light source that emits colored light; a light modulation element that generates image light based on the colored light emitted from the light source; and a projection optical system that projects the image light emitted from the light modulation element. Projectors are categorized by the number of light sources and light modulation elements, for example, single-panel or three-panel projectors. For example, Patent Document 1 discloses a three-panel projector comprising: a light-emitting diode (LED) that emits colored light; a block that emits colored light from its output end in a manner that uniformly distributes the brightness of the colored light incident from the LED; a condenser lens that images the light source image of the colored light emitted from the block onto the entrance pupil of the projection lens; a light modulation element that modulates the colored light into image light; and a projection lens.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2000-180962

[0004] Typically, the wavelength of colored light emitted from an LED is wider than that emitted from a laser diode (LD). In the three-panel projector disclosed in Patent Document 1, since an LED is used as the light source, in addition to the colored light required for image formation, colored light of wavelengths not required for image formation may also be incident on the light modulation element, affecting the lifespan of the light modulation element and potentially reducing the color reproducibility of the projected image. Utility Model Content

[0005] One embodiment of the projector of this invention comprises: a first light source emitting first light of a first wavelength and second light of a second wavelength; a first light guide element having a first substrate and a first reflective film disposed on the first substrate, and having a first incident end and a first exiting end, wherein the first light and second light emitted from the first light source are incident on the first incident end, and the first exiting end emits the first light; a first light modulation element modulating the first wavelength light emitted from the first light guide element based on image information; and a projection optical system projecting the light emitted from the first light modulation element. The first light guide element has a lower reflectivity for the second light than for the first light. 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 yes Figure 2 A side view of the light source and light guide element of the blue light emitting section.

[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 side view of the green light emitting section and the incident side polarizing element of the projector.

[0011] Figure 6 This is a perspective view of the light guide element of the blue light emitting section of a projector according to a second modification of an embodiment.

[0012] Label Explanation

[0013] 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

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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 of the substrate 111 that is parallel to a surface including the D2 and D3 directions. The emitting surface of the light source 121 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 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 light LB is emitted from the emitting surface of the light source 121 toward the +D1 side with a predetermined radiation angle centered on an axis passing through the center of the emitting surface of the light source 121 and parallel to the D1 direction.

[0018] Light source 121 is, for example, composed of an LED emitting blue light LB. The LED emitting blue light LB contains, for example, a gallium nitride (GaN) based semiconductor material as the light emitter. The blue light LB in the blue band includes blue light LB1 in the first band and blue light LB2 in the second band. If light source 121 is composed of an LED, the blue band is wider compared to the case where it is composed of an LD. The blue band is, for example, the band of 400nm to 500nm. The first band is, for example, 440nm to 500nm, preferably including 467nm. The second band is a different band from the first band, for example, 400nm to 440nm. The second band is shorter than the first band and closer to the ultraviolet band. Blue light LB1 corresponds to the first light. Blue light LB2 corresponds to the second light.

[0019] In the blue light LB, the light intensity of blue light LB1 is the same as that of blue light LB2. In addition, in the common description of blue light LB1 and LB2, blue light LB1 and LB2 are sometimes referred to as blue light LB.

[0020] 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, multiple LEDs are arranged in the area occupied by the light source 121 within the plane including the D2 and D3 directions.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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 APE141 emitting blue light LB1, 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.

[0026] 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.

[0027] 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.

[0028] 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 VX perpendicular to the incident end 141a and the optical axis. As it moves from the -D1 side to the +D1 side, it moves away from the imaginary line VX 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 exit end 141b, and the reflecting surface 141r.

[0029] 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 imaginary line VX and the 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 imaginary line VX and the 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 the reflective film 251 of the light guide element 141 has the desired spectral reflectivity, as described later.

[0030] A portion of the blue light LB incident on the light guide element 141 forms an angle smaller than a predetermined angle with respect to the imaginary line VX and the 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 with respect to the imaginary line VX and the 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] Of the four plate-shaped components 241A, 241B, 241C, and 241D, 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 other leg of plate-shaped component 241D is connected to the edge of the other leg of plate-shaped component 241A.

[0037] The plate-shaped component 241 is made of at least one of aluminum (Al) and silver (Ag) as metals, and glass, i.e., silicon dioxide (SiO2), as an insulator and transparent material. When the plate-shaped component 241 is made of Al or Ag, the heat dissipation of the light guide element 141 is improved, and the reflectivity of the blue light LB propagating in the internal space SP141 is increased. When the plate-shaped component 241 is made of glass, the light guide element 141 is lightweight and easy to manufacture. In this embodiment, it is envisioned that the plate-shaped component 241 is made of glass.

[0038] In the light guide element 141, in order to improve the reflectivity of the blue light LB incident from the incident end 141a to the light guide element 141 near the side 141s, a reflective film 251 is provided on the plate surface 241p of the plate-shaped members 241A, 241B, 241C, and 241D that constitute the reflector, facing the internal space SP141. A portion of the blue light LB incident from the incident end 141a to the internal space SP141 of the light guide element 141 is reflected by the reflective film 251 and travels towards the +D1 side.

[0039] The intensities of the blue light LB1 and LB2 emitted from the reflective film 251 after being reflected by the reflective film 251 are different and depend on the incident angle of the blue light LB incident on the reflective film 251. When the reflective film 251 is made of a metal film, for example, the incident angle dependence of the intensity of the blue light LB emitted from the reflective film 251 changes depending on parameters such as the conditions during the evaporation of the metal particles.

[0040] 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 and the reflective film 251 is in the range of 60° to 90°, and the parameters of the reflective film 251 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 part 101 and ray tracing.

[0041] The reflective film 251 is, for example, a metal film that reflects blue light LB1, and is formed by vapor-depositing metal particles constituting the metal film onto the plate surface 241p of the plate member 241. The metal constituting the metal film includes at least one of Al and Ag. In the reflective film 251, a protective film (not shown) may also be provided on the surface of the metal film opposite to the side in contact with the plate member 241.

[0042] Figure 3 This is a side view of the light source 121 and the light guide element 141. The light guide element 141 causes the blue light LB emitted from the light source 121 at a large angle relative to the optical axis, i.e., the blue light LB emitted at a wide angle, to be reflected by the reflective film 251 and propagate in the internal space SP141, thereby adjusting the beam area of ​​the blue light LB to the size of the emission end 141b and focusing it.

[0043] The reflectivity, absorptivity, and transmittance of the reflective film 251 for blue light LB are adjusted according to the conditions during the deposition of metal particles onto the plate surface 241p, namely, the deposition time, the concentration of the metal particles, and the thickness of the metal film formed on the plate surface 241p. In the blue light emitting section 101 of this embodiment, the reflectivity of the reflective film 251 for blue light LB2 is different from that for blue light LB1, and is lower than that for blue light LB1.

[0044] like Figure 3 As shown, the incident angle θ of the blue light LB incident on the plate surface 241p of the plate-shaped component 241 and the reflective film 251 is... in The angle of incidence θ of the blue light LB incident most frequently on the plate surface 241p of the plate member 241 and the position PT2 of the reflective film 251 increases in the D1 direction from the incident end 141a to the emission end 141b, that is, from the -D1 side to the +D1 side. in The angle of incidence θ of the blue light LB incident at position PT1, which is located on the -D1 side relative to position PT2. in At least different, the angle of incidence θ of the blue light LB incident most towards position PT1 is different. in Large. The reflectivity of blue light LB and the density of metal particles at each position in the D1 direction of the reflective film 251 are set such that the reflectivity of blue light LB2 incident at each position is at least lower than the reflectivity of blue light LB1 incident at the same position.

[0045] The reflective film 251 has a lower reflectivity for blue light LB2 than for blue light LB1. Therefore, the intensity of blue light LB1 emitted from the emission end 141b of the light guide element 141 is higher than the intensity of blue light LB2 emitted from the emission end 141b. The amount of blue light LB1 emitted from the emission end 141b is greater than the amount of blue light LB2 emitted from the emission end 141b. The difference in amount between the amount of blue light LB2 emitted from the light source 121 and the amount of blue light LB2 emitted from the emission end 141b is greater than the amount of blue light LB2 emitted from the emission end 141b.

[0046] In detail, the reflectivity of the reflective film 251 of the light guide element 141 for blue light LB2 is lower than the transmittance and absorptance of the reflective film 251 of the light guide element 141 for blue light LB2. The reflectivity and metal particle density of each position along the D1 direction of the reflective film 251 are appropriately set so that the reflectivity of the blue light LB2 incident at each position is lower than the transmittance and absorptance.

[0047] The reflectivity of the reflective film 251 of the light guide element 141 for blue light LB2 is lower than the sum of the transmittance and absorptance of the reflective film 251 for blue light LB2. The sum of the reflectivity, transmittance, and absorptance of the reflective film 251 for blue light LB2 is approximately 100%. That is, the sum of the transmittance and absorptance of the reflective film 251 for blue light LB2 is at least 50%, preferably at least 70%. The reflectivity and density of metal particles at each position in the D1 direction of the reflective film 251 are appropriately set so that the reflectivity of the blue light LB2 incident at each position is lower than the sum of the transmittance and absorptance.

[0048] Blue light LB incident on the reflective film 251 is transmitted through the reflective film 251 and then incident on the plate-shaped member 241, which is transparent relative to the blue light LB. The light then exits from the plate surface 241q on the side of the plate-shaped member 241 opposite to the plate surface 241p to the outside of the light guide element 141. When the transmittance of the reflective film 251 of the light guide element 141 to the blue light LB is higher than its absorptivity, the blue light LB absorbed by the reflective film 251 and the plate-shaped member 241 of the light guide element 141 is suppressed, making it difficult for heat to accumulate in the light guide element 141. This prevents heat-induced shape changes and strain at the light guide element 141, and suppresses the long-term deterioration of the light guide element 141.

[0049] Since the reflectivity, transmittance, absorptivity of the light guide element 141 for blue light LB and the density of metal particles in the reflective film 251 are set as described above, the amount of blue light LB2 emitted from the emission end 141b of the light guide element 141 is less than the amount of blue light LB1 emitted from the emission end 141b of the light guide element 141.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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 is equivalent to a first optical modulation element, which modulates the first band of blue light LB1 in the blue light LB based on image information transmitted by an image forming apparatus such as a computer (not shown), which is externally connected to the optical modulation element 181. The second band of blue light LB2 in the blue light LB is converted by the optical modulation element 181 into a color other than the image light, and does not contribute to the prescribed color balance of the image projected by the projector 301.

[0056] 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 LB1 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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, and is a view of the green light emitting section 102 and the incident side polarizing element 172 when viewed along the D3 direction.

[0061] Light source 122 is supported by substrate 112. Light source 122 is disposed on the +D2 side of a plate surface of substrate 112 that is parallel to the plane including directions D1 and D3. The emitting surface 122a of light source 122 is arranged substantially parallel to the plane including directions D1 and D3, and is located on the opposite side of the plate surface of light source 122 that is in contact with the +D2 side of substrate 112 in the D2 direction. Light source 122 is equivalent to a second light source, emitting green light LG in the green band of the visible spectrum.

[0062] 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.

[0063] 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 may contain, for example, a GaN-based semiconductor material.

[0064] A phosphor 124 is stacked on the emission surface 125a of the +D2 side of the LED body 125. The phosphor 124 is excited by at least a portion of the light emitted from the LED body 125 as excitation light, and emits green light LG from the emission surface 124a as fluorescence. By appropriately selecting the type and material of the LED body 125 and the type and material of the phosphor 124, the phosphor 124 excited by the light emitted from the LED body 125 emits green light LG in the green band.

[0065] The green light LG emitted from phosphor 124, specifically the green band, corresponds to the third light. The green band of the green light LG emitted from phosphor 124 is wider than the green band of the green light emitted from LD. The green band is, for example, the 500nm to 590nm band, preferably including 532nm.

[0066] Another portion of the excitation light emitted from the LED body 125 that is not converted into fluorescence by the phosphor 124 is emitted from the emission surface 124a towards the +D2 side along with the green light LG. This other portion of the excitation light is, for example, blue light LB3 in the blue band. Blue light LB3 corresponds to the fourth light. The blue band of blue light LB3 corresponds to the fourth band. The fourth band is a band different from the third band, for example, 450nm to 490nm. The amount of blue light LB3 is the same as, or less than, the amount of green light LG.

[0067] 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+ ).

[0068] 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.

[0069] The substrate 112 is made of metal, for example, and also functions as a heat dissipation component that receives heat from the light source 122 that emits green light LG and blue light LB3 and releases that heat to the outside space.

[0070] The light guide element 142 is disposed in the optical path of the green light LG and the blue light LB3 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.

[0071] 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.

[0072] The size of the incident end 142a in the plane encompassing both directions D1 and D3 can be the same as the size of the emitting surface 122a of the light source 122 in the plane encompassing both directions D1 and D3, but is preferably moderately larger than the size of the emitting surface 122a in the plane encompassing both directions D1 and D3. At the incident end 142a, the dimension of the opening API 142 through which the green light LG and blue light LB3 are incident, along the long side parallel to the D1 direction, is 1 mm or more and 3 mm or less, preferably about 2 mm.

[0073] 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.

[0074] 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.

[0075] Green light LG and blue light LB3 emitted from light source 122 are incident on light guide element 142 from incident end 142a. In light guide element 142, the internal space SP142, surrounded by incident end 142a, emission end 142b, and reflecting surface 142r, is the region where at least a portion of green light LG and blue light LB3 propagate. The size of internal space SP142 within the plane encompassing directions D1 and D3 increases as it moves from the -D2 side to the +D2 side in direction D2. Furthermore, as it moves from the -D2 side to 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] The paths of the green light LG and blue light LB3 in the internal space SP142 vary depending on the incident angle towards 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 and blue light LB3 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 and blue light LB3, with their illuminance distribution homogenized, are emitted from the exit end 142b towards the +D2 side.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] The edge of one leg of the first plate-shaped member 242 is connected to the edge of one leg of the second plate-shaped member 242. The edge of the other leg of the second plate-shaped member 242 is connected to the edge of one leg of the third plate-shaped member 242. The edge of the other leg of the third plate-shaped member 242 is connected to the edge of one leg of the fourth plate-shaped member 242. The edge of the other leg of the fourth plate-shaped member 242 is connected to the edge of the other leg of the first plate-shaped member 242.

[0084] The plate-shaped component 242 is made of at least one of Al, Ag, and glass (SiO2), preferably the same material as the plate-shaped component 241. When the plate-shaped component 242 is made of Al or Ag, the heat dissipation of the light guide element 142 is improved, and the reflectivity for the green light LG and blue light LB3 propagating in the internal space SP142 is increased. When the plate-shaped component 242 is made of glass, the light guide element 142 is lightweight and easier to manufacture. In this embodiment, it is envisioned that the plate-shaped component 242 is made of glass.

[0085] 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 onto the light guide element 142 near the side 142s, a reflective film 252 is provided on the plate surface opposite to the side 142s, i.e., the plate surface 242p facing the internal space SP142, of the plate-shaped member constituting the reflector. A portion of the green light LG containing light ray Lg2 and the blue light LB3 incident from the incident end 142a onto the internal space SP142 of the light guide element 142 are reflected by the reflective film 252 and travel towards the +D2 side.

[0086] The green light LG and blue light LB3 reflected by the reflective film 252 and emitted from the reflective film 252 have different intensities, depending on the incident angles of the green light LG and blue light LB3 incident on the reflective film 252. When the reflective film 252 is made of a metal film, for example, the incident angle dependence of the intensity of the green light LG and blue light LB3 emitted from the reflective film 252 changes depending on parameters such as the conditions during the deposition of metal particles.

[0087] 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 angles of the green light LG and blue light LB3, which have the highest intensity emitted from the reflective surface 142r and the reflective film 252, are in the range of 60° to 90°, and the parameters of the reflective film 252 are appropriately determined. The relationship between the incident angles of the green light LG and blue light LB3 incident on the reflective surface 142r and the reflective film 252 and the intensity of the green light LG and blue light LB3 emitted from the reflective surface 142r and the reflective film 252 is obtained through numerical simulation based on the structure of the green light emitting part 102 and ray tracing.

[0088] The reflective film 252 is, for example, a metal film that reflects green light LG, and is formed by depositing metal particles constituting the metal film onto the plate surface 242p of the plate member 242. The metal constituting the metal film includes at least one of Al and Ag. In the reflective film 252, a protective film (not shown) may also be provided on the surface of the metal film opposite to the side that is in contact with the plate member 242.

[0089] The light guide element 142 causes the green light LG emitted from the light source 122 at a large angle relative to the optical axis, i.e., the green light LG emitted at a wide angle, to be reflected by the reflective film 252 and propagate in the internal space SP142, thereby adjusting the beam area of ​​the green light LG to the size of the emission end 142b and focusing it.

[0090] The reflectivity, absorptivity, and transmittance of the reflective film 252 for green light LG are adjusted according to the conditions during the deposition of metal particles onto the plate surface 242p, namely, the deposition time, the concentration of the metal particles, and the thickness of the metal film formed on the plate surface 242p. In the green light emitting section 102 of this embodiment, the reflectivity of the reflective film 252 for blue light LB3 is different from the reflectivity of the reflective film 252 for green light LG, and is lower than the reflectivity of the reflective film 252 for green light LG.

[0091] The incident angle θ of green light LG and blue light LB3 incident on the plate surface 242p of the plate member 242 and the reflective film 252 in The reflectivity of the reflective film 252 at each position in the D2 direction increases from the incident end 142a to the emission end 142b, i.e. from the -D2 side to the +D2 side. The reflectivity of the green light LG and the density of the metal particles at each position in the D2 direction are set such that the reflectivity of the blue light LB3 incident at each position is at least lower than the reflectivity of the green light LG incident at the same position.

[0092] The reflective film 252 has a lower reflectivity for blue light LB3 than for green light LG. Therefore, the light intensity of green light LG emitted from the emission end 142b of the light guide element 142 is higher than the light intensity of blue light LB3 emitted from the emission end 142b. The amount of green light LG emitted from the emission end 142b is greater than the amount of blue light LB3 emitted from the emission end 142b. The difference in light intensity between the amount of blue light LB3 emitted from the light source 122 and the amount of blue light LB3 emitted from the emission end 142b is greater than the amount of blue light LB3 emitted from the emission end 142b.

[0093] In detail, the reflectivity of the reflective film 252 of the light guide element 142 for blue light LB3 is lower than the transmittance and absorptance of the reflective film 252 of the light guide element 142 for blue light LB3. By appropriately setting the reflectivity and metal particle density of each position along the D2 direction of the reflective film 252 for blue light LB3, the reflectivity of the blue light LB3 incident at each position is lower than the transmittance and absorptance.

[0094] The reflectivity of the reflective film 252 of the light guide element 142 for blue light LB3 is lower than the sum of the transmittance and absorptance of the reflective film 252 for blue light LB3. The sum of the reflectivity, transmittance, and absorptance of the reflective film 252 for blue light LB3 is approximately 100%. That is, the sum of the transmittance and absorptance of the reflective film 252 for blue light LB3 is at least 50%, preferably at least 70%. The reflectivity of the reflective film 252 for blue light LB3 and the density of metal particles at each position in the D2 direction are appropriately set so that the reflectivity of the blue light LB3 incident at each position is lower than the sum of the transmittance and absorptance.

[0095] The green light LG and blue light LB3 incident on the reflective film 252 are transmitted through the reflective film 252 and then incident on the plate-shaped member 242, which is transparent relative to the green light LG and blue light LB3. The light then exits from the plate surface 242q on the side of the plate-shaped member 242 opposite to the plate surface 242p, towards the outside of the light guide element 142. When the transmittance of the reflective film 252 of the light guide element 142 for the green light LG and blue light LB3 is higher than its absorptivity, the green light LG and blue light LB3 absorbed by the reflective film 252 and the plate-shaped member 242 of the light guide element 142 are suppressed, making it difficult for heat to accumulate in the light guide element 142. This prevents heat-induced shape changes and strain at the light guide element 142, and suppresses the long-term degradation of the light guide element 142.

[0096] Since the reflectivity, transmittance, absorptivity of the light guide element 142 for green light LG and blue light LB3, as well as the density of metal particles in the reflective film 252, are set as described above, the amount of blue light LB3 emitted from the emission end 142b of the light guide element 142 is less than the amount of green light LG emitted from the emission end 142b of the light guide element 142.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] like Figure 1 As shown, the light 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 both the D1 and D3 directions. The light modulation element 182 is equivalent to a second light modulation element, which modulates the third band of the green light LG and the blue light LB3 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 light modulation element 182. The fourth band of blue light LB3 is converted by the light modulation element 182 into a color other than the image light, and does not contribute to the prescribed color balance of the image projected by the projector 301.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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 toward the -D1 side.

[0110] 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 surface of the substrate 113 that is parallel to a surface including both the D2 and D3 directions. The emitting surface of the light source 123 is arranged substantially parallel to the surface including both 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 is equivalent to a third light source, emitting red light (LR) in the red band of the visible spectrum.

[0111] Light source 123 is, for example, composed of an LED emitting red light LR. The LED emitting red light LR contains, for example, aluminum gallium indium phosphide (AlGaInP) as the light emitter. The red light LR in the red band includes red light LR1 in the 5th band and red light LR2 in the 6th band. If light source 123 is composed of an LED, the red band is wider compared to the case where it is composed of an LD. The red band is, for example, the band from 590 nm to 700 nm. The 5th band is, for example, from 590 nm to 650 nm, preferably including 630 nm. The 6th band is a different band from the 5th band, for example, from 650 nm to 700 nm. The 6th band is a longer band than the 5th band and is closer to the infrared band than the 5th band. Red light LR1 corresponds to the 5th light. Red light LR2 corresponds to the 6th light.

[0112] In the red light LR, the light intensity of red light LR1 is the same as that of red light LR2. In addition, in the common description of red light LR1 and LR2, red light LR1 and LR2 are sometimes uniformly recorded as red light LR.

[0113] 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 the plane including the D2 and D3 directions.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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 emitting the red light LR1 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.

[0119] 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.

[0120] 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.

[0121] 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 an imaginary line (not shown) perpendicular to the incident end 143a 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 within 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.

[0122] 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.

[0123] 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.

[0124] 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 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 the D2 and D3 directions. The red light LR with homogenized illuminance distribution is emitted from the emission end 143b towards the -D1 side.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] The plate-shaped component 243 is made of at least one of Al, Ag, and glass (SiO2), preferably the same material as the plate-shaped components 241 and 242. When the plate-shaped component 243 is made of Al or Ag, the heat dissipation of the light guide element 143 is improved, and the reflectivity of the blue light LB propagating in the internal space is increased. When the plate-shaped component 243 is made of glass, the light guide element 143 is lightweight and easier to manufacture. In this embodiment, it is envisioned that the plate-shaped component 243 is made of glass.

[0129] Four plate-shaped components 243 are cut out in a trapezoidal shape from the base material. A reflective film 253 is formed on one surface of the base material, which is 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 out from the base material 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.

[0130] 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.

[0131] The intensity of the red light LR reflected by the reflective film 253 and emitted from 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 metal film, the incident angle dependence of the intensity of the red light LR emitted from the reflective film 253 changes, for example, depending on parameters such as the deposition of metal particles.

[0132] 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 reflective film 253 are appropriately determined. The relationship between the incident angle of the red light LR incident on the reflective surface 143r and the reflective film 253 and the intensity of the red light LR emitted from the reflective surface 143r and the reflective film 253 is also obtained through numerical simulation based on the structure of the red light emitting part 103 and ray tracing.

[0133] The reflective film 253 is, for example, a metal film that reflects red light LR1, and is formed by depositing metal particles constituting the metal film onto the plate surface 243p of the plate member 243. The metal constituting the metal film includes at least one of Al and Ag. In the reflective film 253, a protective film (not shown) may also be provided on the surface of the metal film opposite to the side in contact with the plate member 243.

[0134] The light guide element 143 causes the red light LR emitted from the light source 123 within a range up to a large angle relative to the optical axis, i.e., the red light LR emitted at a wide angle, to be reflected by the reflective film 253 and propagate in the internal space surrounded by the incident end 143a, the emitting end 143b, and the reflective surface 143r, thereby adjusting the beam area of ​​the red light LR to the size of the emitting end 143b and focusing it.

[0135] The reflectivity, absorptivity, and transmittance of the reflective film 253 for red light LR are adjusted according to the conditions during the deposition of metal particles onto the plate surface 243p, namely, the deposition time, the concentration of metal particles, and the thickness of the metal film formed on the plate surface 243p. In the red light emitting section 103 of this embodiment, the reflectivity of the reflective film 253 for red light LR2 is different from that for red light LR1, and is lower than that for red light LR1.

[0136] like Figure 3 As shown, the incident angle θ of the red light LR incident on the plate surface 243p of the plate-shaped component 243 and the reflective film 253 is... inThe angle of incidence θ of the red light LR incident most frequently on the plate surface 243p of the plate member 243 and the position PT2 of the reflective film 253 increases in the D1 direction from the incident end 143a to the emission end 143b, that is, from the +D1 side to the -D1 side. in The incident angle θ of the most red light LR incident at position PT1, which is located on the +D1 side relative to position PT2. in At least they are different, compared to the incident angle θ of the red light LR that is most incident on position PT1. in The reflectivity of the red light LR and the density of the metal particles at each position in the D1 direction of the reflective film 253 are set such that the reflectivity of the red light LR2 incident at each position is at least lower than the reflectivity of the red light LR1 incident at the same position.

[0137] The reflective film 253 has a lower reflectivity for red light LR2 than for red light LR1. Therefore, the intensity of red light LR1 emitted from the emission end 143b of the light guide element 143 is higher than the intensity of red light LR2 emitted from the emission end 143b. The amount of red light LR1 emitted from the emission end 143b is greater than the amount of red light LR2 emitted from the emission end 143b. The difference in amount between the red light LR2 emitted from the light source 123 and the red light LR2 emitted from the emission end 143b is greater than the amount of red light LR2 emitted from the emission end 143b.

[0138] In detail, the reflectivity of the reflective film 253 of the light guide element 143 for red light LR2 is lower than the transmittance and absorptance of the reflective film 253 of the light guide element 143 for red light LR2. By appropriately setting the reflectivity and metal particle density of each position of the reflective film 253 in the D1 direction for red light LR2, the reflectivity of red light LR2 incident at each position is lower than the transmittance and absorptance.

[0139] The reflectivity of the reflective film 253 of the light guide element 143 for red light LR2 is lower than the sum of the transmittance and absorptance of the reflective film 253 for red light LR2. The sum of the reflectivity, transmittance, and absorptance of the reflective film 253 for red light LR2 is approximately 100%. That is, the sum of the transmittance and absorptance of the reflective film 253 for red light LR2 is at least 50%, preferably at least 70%. The reflectivity of the reflective film 253 for red light LR2 and the density of metal particles at each position in the D1 direction are appropriately set so that the reflectivity of the red light LR2 incident at each position is lower than the sum of the transmittance and absorptance.

[0140] The red light LR incident on the reflective film 253 is transmitted through the reflective film 253 and then passes through the plate-shaped member 243, which is transparent relative to the red light LR. The light is then emitted from the side of the plate-shaped member 243 opposite to the plate surface 241p and facing outwards, towards the outside of the light guide element 143. When the transmittance of the reflective film 253 of the light guide element 143 to the red light LR is higher than its absorptivity, the red light LR absorbed by the reflective film 253 and the plate-shaped member 243 of the light guide element 143 is suppressed, making it difficult for heat to accumulate in the light guide element 143. This prevents heat-induced shape changes and strain at the light guide element 143, and suppresses the long-term degradation of the light guide element 143.

[0141] Since the reflectivity, transmittance, absorptivity of the light guide element 143 for the red light LR and the density of the metal particles in the reflective film 253 are set as described above, the amount of red light LR2 emitted from the emission end 143b of the light guide element 143 is less than the amount of red light LR1 emitted from the emission end 143b of the light guide element 143.

[0142] 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.

[0143] 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.

[0144] 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 overlapping 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 with a suitable distance between it and the optical modulation element 183 in the D1 direction.

[0145] 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.

[0146] 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.

[0147] An optical modulation element 183 is disposed on 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 fifth band of red light LR1 in the red light LR based on image information transmitted by an image forming apparatus such as a computer (not shown), which is externally connected to the optical modulation element 183. The sixth band of red light LR2 in the red light LR is converted by the optical modulation element 183 into a color light other than the object of the image light, and does not contribute to the prescribed color balance of the image projected by the projector 301.

[0148] 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 LR1 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.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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 dichroic prism 210 emits the full-color image light IM from the emission surface 210b along the D2 direction toward the +D2 side.

[0156] 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.

[0157] 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.

[0158] 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 modulation element (first light modulation element) 181, and a projection optical system 250. The light source 121 emits blue light (first light) LB1 in a first wavelength band and blue light (second light) LB2 in a second wavelength band. The light guide element 141 has a plate-shaped member (first substrate) 241 and a reflective film (first reflective film) 251 disposed on the plate-shaped member 241. The light guide element 141 has an incident end (first incident end) 141a, into which blue light LB1 and LB2 emitted from the light source 121 are incident; and an emitting end (first emitting end) 141b, which emits blue light LB1. The light modulation element 181 modulates the first-band blue light LB1 emitted from the light guide element 141 based on image information. The projection optical system 250 projects the image light (light) IM emitted from the light modulation element 181. In the projector 301 of this embodiment, the reflectivity of the light guide element 141 for blue light LB2 is lower than that for blue light LB1.

[0159] The reflectivity of the light guide element 141 includes both: the reflectivity caused solely by the reflectivity of the reflective film 251, as in this embodiment; and the combined reflectivity caused by the reflectivity of the plate-shaped member 241 and the reflectivity of the reflective film 251, which is adjusted by the transmittance of blue light LB in the reflective film 251. In the projector 301 of this embodiment, the reflectivity of the blue light LB2 in the light guide element 141 for the second band not used in the subsequent stage to form the projected image is lower than the reflectivity of the blue light LB1 in the first band used to form the projected image. Therefore, unwanted light during the formation of the projected image can be suppressed by using the light guide element 141, reducing the amount of colored light other than the conversion target for image light conversion in the colored light incident on the light modulation element 181. According to the projector 301 of this embodiment, the impact on the lifespan of the light modulation element 181 and the reduction in the color reproducibility of the projected image can be suppressed. In other words, the projector 301 according to this embodiment can achieve long-term use of the light modulation element 181 and can improve the color reproduction of the projected image.

[0160] The projector 301 of this embodiment further includes a light source (second light source) 122, a light source (third light source) 123, a light guide element (second light guide element) 142, a light guide element (third light guide element) 143, a light modulation element (second light modulation element) 182, and a light modulation element (third light modulation element) 183. The light source 122 emits green light (third light) LG in the third band and blue light (fourth light) LB3 in the fourth band. The light source 123 emits red light (fifth light) LR1 in the fifth band and red light (sixth light) LR2 in the sixth band. The light guide element 142 has a plate-shaped member (second substrate) 242 and a reflective film (second reflective film) 252 disposed on the plate-shaped member 242. The light guide element 142 has an incident end (second incident end) 142a, to which green light LG and blue light LB3 emitted from the light source 122 are incident; and an exit end (second exit end) 142b, which emits green light LG. The light guide element 143 has a plate-shaped member (third substrate) 243 and a reflective film (third reflective film) 253 disposed on the plate-shaped member 243. The light guide element 143 has an incident end (third incident end) 143a, to which red light LR1 and LR2 emitted from the light source 123 are incident; and an exit end (first exit end) 143b, which emits red light LR1. The light modulation element 182 modulates the third-band green light LG emitted from the light guide element 142 based on image information. The light modulation element 183 modulates the red light LR1 of the fifth band emitted from the light guide element 143 based on image information. The projection optical system 250 combines the image light IG and IR emitted from the light modulation elements 182 and 183 with the image light IB emitted from the light modulation element 181, and projects the generated image light (light) IM. In the projector 301 of this embodiment, the reflectivity of the light guide element 142 for blue light LB3 is lower than that for green light LG. The reflectivity of the light guide element 143 for red light LR2 is lower than that for red light LR1.

[0161] The reflectivity of the light guide element 142 includes both of the following: the reflectivity caused solely by the reflectivity of the reflective film 252, as in this embodiment; and the combined reflectivity caused by the reflectivity of the plate member 242 and the reflectivity of the reflective film 252, where the transmittance of green light LG in the reflective film 252 is adjusted. Regarding the reflectivity of the light guide element 143, it also includes both of the following: the reflectivity caused solely by the reflectivity of the reflective film 253; and the combined reflectivity caused by the reflectivity of the plate member 243 and the reflectivity of the reflective film 253, where the transmittance of red light LR in the reflective film 253 is adjusted. In the projector 301 of this embodiment, the reflectivity of the blue light LB3 (band 4, not used in the subsequent stage to form the projected image) in the light guide element 142 is lower than that of the green light LG (band 3, used in the subsequent stage to form the projected image). Therefore, the light guide element 142 can suppress unwanted light during the formation of the projected image, reducing the amount of non-conversion-target light in the incident light on the light modulation element 182. Similarly, the reflectivity of the red light LR2 (band 6, not used in the subsequent stage to form the projected image) in the light guide element 143 is lower than that of the red light LR1 (band 5, used in the subsequent stage to form the projected image). Therefore, the light guide element 143 can suppress unwanted light during the formation of the projected image, reducing the amount of non-conversion-target light in the incident light on the light modulation element 183. According to the projector 301 of this embodiment, the impact on the lifespan of the light modulation element 181 and the reduction in the color reproducibility of the projected image can be suppressed. Furthermore, the projector 301 according to this embodiment can suppress the increase in manufacturing costs and synthesize three colors to expand the color gamut that can be represented by the projected image.

[0162] In the projector 301 of this embodiment, the first light is blue light LB1 in the blue band, and the second light is blue light LB2 in the blue band that is shorter in wavelength than the first light.

[0163] In the projector 301 of this embodiment, among the colored light of the projected image light, the energy of the blue light LB2 in the second band (short wavelength side of the blue band) is higher than that of the blue light LB1 in the first band (long wavelength side of the second band), as well as the energy of the green light LG and the red light LR. Therefore, the liquid crystal layer of the light modulation element of the illuminated light deteriorates. According to the projector 301 of this embodiment, the blue light LB2 can be absorbed by the light guide element 141, which can suppress the deterioration of optical elements and components, including the light modulation element 181, located after the light guide element 141, and improve the reliability of optical elements and components located after the light guide element 141.

[0164] In the projector 301 of this embodiment, the light source (first light source) 122 converts the excitation light, which is blue light, into fluorescence by incidenting it onto the phosphor (fluorescent layer) 124, and emits green light LG. The first light is green light LG, which is fluorescence converted from a part of the excitation light. The second light is blue light LB3, which is another part of the excitation light.

[0165] In the projector 301 of this embodiment, when the light source 122 having the phosphor 124 is regarded as the first light source, the blue light LB3 that is not converted by the phosphor 124 does not need to be used in the subsequent stage to generate the projected image light. According to the projector 301 of this embodiment, unwanted light during the formation of the projected image can be suppressed by using the light guide element 142, thus reducing the overall size of the device and improving color reproduction.

[0166] In the projector 301 of this embodiment, the first light is blue light LB. The third light is green light LG. The fifth light is red light LR. The projector 301 of this embodiment can generate and project image light IM with high color reproducibility.

[0167] In the projector 301 of this embodiment, the first band contains 467 nm. The third band contains 532 nm. The fifth band contains 630 nm. In the projector 301 of this embodiment, the first, third, and fifth 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.

[0168] In the projector 301 of this embodiment, the difference between the amount of blue light LB2 emitted from the light source 121 and the amount of blue light LB2 emitted from the emission end 141b of the light guide element 141 is greater than the amount of blue light LB2 emitted from the emission end 141b.

[0169] In the projector 301 of this embodiment, the loss of blue light LB1 can be suppressed in the light guide element 141, and the amount of blue light LB2 can be reduced, thereby improving the light utilization efficiency.

[0170] In the projector 301 of this embodiment, the reflectivity of the light guide element 141 and the reflective film 251 to the blue light LB2 is lower than the transmittance of the light guide element 141 and the reflective film 251 to the blue light LB2.

[0171] In the projector 301 of this embodiment, the amount of blue light LB2 reflected by the light guide element 141 and the reflective film 251 is less than the amount of blue light LB2 transmitted through the light guide element 141 and the reflective film 251. According to the projector 301 of this embodiment, useless blue light LB2 during the formation of the projected image guided by the light guide element 141 to the emission end 141b can be efficiently suppressed, and blue light LB2 can be emitted outside the optical path of green light LG outside the light guide element 141. Furthermore, if the plate-shaped member 241 is translucent, heat is less likely to accumulate in the light guide element 141. According to the projector 301 of this embodiment, heat-induced deformation and strain of the light guide element 141 can be prevented, and the deterioration of the light guide element 141 over time can be suppressed.

[0172] In the projector 301 of this embodiment, the reflectivity of the light guide element 141 and the reflective film 251 to the blue light LB2 is lower than the absorption rate of the light guide element 141 and the reflective film 251 to the blue light LB2.

[0173] In the projector 301 of this embodiment, the amount of blue light LB2 reflected by the light guide element 141 and the reflective film 251 is less than the amount of blue light LB2 absorbed by the light guide element 141, i.e., the reflective film 251. According to the projector 301 of this embodiment, the generation of stray light caused by blue light LB2 can be prevented. Furthermore, according to the projector 301 of this embodiment, heat dissipation is efficiently achieved using the plate-shaped component 241, eliminating the need for a separate component for absorbing blue light LB2 from the light guide element 141, thus reducing the overall size of the device.

[0174] In the projector 301 of this embodiment, the reflectivity of the light guide element 141 to the blue light LB2 is lower than the sum of the transmittance and absorptivity of the light guide element 141 to the blue light LB2.

[0175] In the projector 301 of this embodiment, the amount of blue light LB2 guided to the emission end 141b can be suppressed by the transmission and absorption of blue light LB2 through the reflective film 251 and the plate-shaped member 241 of the light guide element 141. According to the projector 301 of this embodiment, the amount of blue light LB2 guided to the emission end 141b can be easily suppressed, and the design freedom of the light guide element 141, including the conditions, various parameters, and material selection of the plate-shaped member 241 during the evaporation of the metal particles including the reflective film 251, can be improved.

[0176] In the projector 301 of this embodiment, the plate-shaped component 241 of the light guide element 141 is made of glass. According to the projector 301 of this embodiment, the light guide element 141 can be made lightweight, and the light guide element 141 can be easily manufactured and properly processed.

[0177] In the projector 301 of this embodiment, the plate-shaped component 241 of the light guide element 141 is made of glass. The reflective film 251 of the light guide element 141 is made of metal and reflects blue light LB1.

[0178] In the projector 301 of this embodiment, glass, which is easy to ensure surface accuracy, is used as the material for the plate-shaped member 241, and a reflective film 251 is formed on the plate surface 241p of the glass plate-shaped member 241 with high surface accuracy. According to the projector 301 of this embodiment, the optical characteristics for blue light LB2 at the light guide element 141 can be adjusted with high precision, and the light guide element 141 can be made lightweight.

[0179] 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.

[0180] In the projector 301 of this embodiment, blue light LB1, green light LG, and red light LR1, 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.

[0181] 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.

[0182] 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 LB1, green light LG, and red light LR1 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 LB1, green light LG, and red light LR1 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 LB1, green light LG, and red light LR1 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.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] 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.

[0187] Variations

[0188] Furthermore, in the projector 301 of this embodiment, as described above, the plate-shaped component 241 is envisioned to be made of glass, but the plate-shaped component 241 may also contain Al, Ag, or other metals. The projector with this first modified structure can improve the heat dissipation of the light guide element 141 and the plate-shaped component 241, and easily improve the reflectivity of visible light including blue light LB1, green light LG, and red light LR1.

[0189] Furthermore, in the projector of the first modification of this embodiment, the plate-shaped member 241 of the light guide element 141 is made of metal. The reflective film 251 is a metal film that reflects blue light LB1. According to the projector of the first modification of this embodiment, the thermal conductivity of the plate-shaped member 241 is improved. Even if the blue light LB2 is not completely absorbed by the reflective film 251 due to the relationship between the thickness of the reflective film 251 (which is a metal film) and the amount of incident blue light LB2, the plate-shaped member 241 can efficiently dissipate heat or cool the light, preventing deformation and strain of the light guide element 141 and suppressing its deterioration over time.

[0190] Figure 6 This is a perspective view of the light guide element 141 of the blue light emitting section 101 of the projector in the second modification of this embodiment. Figure 6 As shown, in the light guide element 141, the reflective film 251 may not be disposed on the plate surface 241p in each of the plate-shaped members 241A, 241B, 241C, 241D, but on the plate surface 241q facing the outside of the light guide element 141. In this second variation, the blue light LB incident from the incident end 141a of the light guide element 141 into the internal space SP141, and the blue light LB incident on the reflective surface 141r, is refracted at the plate-shaped members 241A, 241B, 241C, 241D made of glass, and then incident on the reflective film 251. The blue light LB reflected by the reflective film 251 is again refracted at the plate-shaped members 241A, 241B, 241C, 241D and propagates into the internal space SP141. The blue light LB2 incident on the reflective film 251 and transmitted through it is emitted out of the light guide element 141. Blue light LB2 passing through the reflective film 251 and blue light LB2 absorbed by the reflective film 251 do not incident on the light modulation element 181.

[0191] In the projector of the second variation of this embodiment, the plate-shaped member 241 is made of glass. The plate-shaped member 241 has a plate surface (first surface) 241p facing the internal space SP141 of the light guide element 141, and a plate surface (second surface) 241q facing the outside of the light guide element 141 and located on the opposite side of the plate surface 241p. A reflective film 251 is disposed on the plate surface 241q of the plate-shaped member 241 and reflects blue light LB1.

[0192] In the projector of the second variation of this embodiment, similarly to the case where the reflective film 251 is disposed on the plate surface 241p of the plate member 241, the reflective film 251 is formed on the plate surface 241q of the plate member 241, which is made of glass and has a high surface accuracy. According to the projector of the second variation of this embodiment, the optical characteristics for blue light LB2 at the light guide element 141 can be adjusted with high precision, and the light guide element 141 can be made lightweight.

[0193] Furthermore, as another variation, in the projector 301 of this embodiment, when the reflective film 251 is composed of a dielectric multilayer film, parameters such as the number of low-refractive-index layers and high-refractive-index layers constituting the dielectric multilayer film, the refractive index of the low-refractive-index 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 are appropriately set to make the reflectivity of blue light LB2 lower than that of blue light LB1. Similarly, when the reflective film 252 is composed of a dielectric multilayer film, parameters such as the number of low-refractive-index layers and high-refractive-index layers constituting the dielectric multilayer film, the refractive index of the low-refractive-index 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 are appropriately set to make the reflectivity of blue light LB3 lower than that of green light LG. When the reflective film 253 is composed of a dielectric multilayer film, for example, 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 are appropriately set so that the reflectivity of red light LR2 is lower than that of red light LR1.

[0194] 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.

[0195] 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.

[0196] Alternatively, the projector in this embodiment can also be a single-panel projector, which includes: a first light source having an LED emitting white light; a first light guide element that homogenizes the in-plane illuminance of the white light emitted from the light source; a first light modulation element that modulates the colored light emitted from the first light guide element based on image information; and a projection optical system that projects image light emitted from the first light modulation element. According to the single-panel projector of this embodiment, even when the first light source emits blue light LB2 in a band close to the ultraviolet range, the amount of blue light LB2 incident on the first light modulation element can be suppressed by the first light guide element, thereby suppressing the degradation of optical elements and components, including the light modulation element, and improving the color reproduction of the projected image.

[0197] This is a summary of the disclosure.

[0198] The following is a summary published in this note.

[0199] Postscript 1

[0200] A projector comprising: a first light source emitting first light of a first wavelength and second light of a second wavelength; a first light guide element having a first substrate and a first reflective film disposed on the first substrate, and having a first incident end and a first exiting end, wherein the first light and the second light emitted from the first light source are incident on the first incident end, and the first exiting end emits the first light; a first light modulation element modulating the first wavelength light emitted from the first light guide element based on image information; and a projection optical system projecting the light emitted from the first light modulation element, wherein the first light guide element has a lower reflectivity for the second light than for the first light.

[0201] In the structure described in Appendix 1, the reflectivity of the second light in the second band, which is not required for the formation of image light in the light modulation element, is lower than the reflectivity of the first light in the first band, which is required for the formation of image light. According to the structure described in Appendix 1, the second light can be reduced by utilizing the first light guide element disposed in front of the first light modulation element, thus suppressing the degradation of the light modulation element and improving the color reproduction of the image projected by the projector.

[0202] Appendix 2

[0203] According to the projector described in Appendix 1, the projector further comprises: a second light source emitting a third light of a third wavelength band and a fourth light of a fourth wavelength band; a third light source emitting a fifth light of a fifth wavelength band and a sixth light of a sixth wavelength band; a second light guide element having a second substrate and a second reflective film disposed on the second substrate, and having a second incident end and a second emission end, wherein the third light and the fourth light emitted from the second light source are incident on the second incident end, and the third light is emitted from the second emission end; and a third light guide element having a third substrate and a third reflective film disposed on the third substrate, and having a second incident end and a second emission end. The light source comprises a third incident end and a third exiting end, wherein the fifth light and the sixth light emitted from the third light source are incident on the third incident end, and the fifth light is emitted from the third exiting end; a second light modulation element modulates the third band light emitted from the second light guide element based on image information; and a third light modulation element modulates the fifth band light emitted from the third light guide element based on image information, wherein the second light guide element has a lower reflectivity for the fourth light than for the third light, and the third light guide element has a lower reflectivity for the sixth light than for the fifth light.

[0204] According to the structure in Appendix 2, it is possible to suppress the increase in manufacturing costs and synthesize the three colors of light, namely the first light, the third light and the fifth light, thereby expanding the color gamut of the image projected by the projector.

[0205] Appendix 3

[0206] According to the projector described in Appendix 1 or Appendix 2, the first light is blue light and the second light is blue light in a wavelength band shorter than that of the first light.

[0207] According to the structure in Appendix 3, the blue light in the short wavelength band that may cause the degradation of optical elements and components can be reduced by using the first light guide element, thereby improving the reliability of the optical modulation element, other optical elements and components arranged in the subsequent stage of the first light guide element.

[0208] Appendix 4

[0209] The projector according to any one of Annexes 1 to 3, wherein the first light source converts the excitation light into fluorescence by irradiating the fluorescent layer with excitation light and emits the fluorescence, the first light being the fluorescence converted from a portion of the excitation light, and the second light being another portion of the excitation light.

[0210] In the structure described in Appendix 4, the first light source has a fluorescent layer. By irradiating the fluorescent layer with excitation light from the LED body, fluorescent light is emitted from the fluorescent layer as fluorescence. According to the structure described in Appendix 4, unwanted light can be suppressed using the first light guide element, thus reducing the overall size of the projector device and improving the color reproduction of the image projected by the projector.

[0211] Appendix 5

[0212] According to the projector described in Appendix 2, the first light is blue light, the third light is green light, and the fifth light is red light.

[0213] According to the structure in Appendix 5, it is possible to generate image light with high color reproducibility.

[0214] Appendix 6

[0215] According to the projector described in Appendix 3, the first band contains 467 nm, the third band contains 532 nm, and the fifth band contains 630 nm.

[0216] According to the structure in Appendix 6, since bands 1, 3 and 5 contain the primary color wavelengths of BT.2020, which serve as representative color standards, they are able to meet color reproduction standards.

[0217] Appendix 7

[0218] The projector according to any one of Annexes 1 to 6, wherein the difference between the amount of light emitted from the first light source and the amount of light emitted from the first emission end is greater than the amount of light emitted from the first emission end.

[0219] According to the structure in Appendix 7, it is possible to suppress the loss of colored light and improve the light utilization efficiency in the projector.

[0220] Postscript 8

[0221] The projector according to any one of Annexes 1 to 7, wherein the reflectivity of the first light guide element to the second light is lower than the transmittance of the first light guide element to the second light.

[0222] According to the structure in Appendix 8, heat is difficult to accumulate in the first light guide element, which can prevent deformation and strain of the first light guide element and suppress the deterioration of the first light guide element over the years.

[0223] Postscript 9

[0224] The projector according to any one of Annexes 1 to 7, wherein the reflectivity of the first light guide element to the second light is lower than the absorptivity of the first light guide element to the second light.

[0225] According to the structure in Appendix 9, stray light is suppressed, and there is no need to set up additional optical elements or components for absorbing the second light. Therefore, it is possible to suppress the overall size of the projector device and to efficiently dissipate heat using the first substrate of the first light guide element.

[0226] Postscript 10

[0227] The projector according to any one of Annexes 1 to 7, wherein the reflectivity of the first light guide element to the second light is less than the sum of the transmittance and absorptivity of the first light guide element to the second light.

[0228] According to the structure in Appendix 10, the second light guided to the first emission end can be easily suppressed in accordance with the transmission and absorption of the second light at the first light guide element, thereby increasing the design freedom of the first light guide element.

[0229] Postscript 11

[0230] According to the projector described in Appendix 8, the material of the first substrate is glass.

[0231] According to the structure in Appendix 11, the first light guide element can be made lightweight, and the first light guide element can be easily manufactured and processed.

[0232] Postscript 12

[0233] According to Appendix 9, the projector is made of aluminum or silver.

[0234] According to the structure in Appendix 12, the heat dissipation of the first light guide element can be improved, and the reflectivity of the first reflective film of the first light guide element to the first light can be easily improved.

[0235] Postscript 13

[0236] According to the projector described in Appendix 12, the first reflective film is a metal film that reflects the first light.

[0237] According to the structure in Appendix 13, even if a second light that is not completely absorbed by the first reflective film is generated based on the relationship between the design value such as the thickness of the first reflective film and the amount of incident second light, the heat dissipation and heat dissipation properties of the first light guide element can still be obtained.

[0238] Postscript 14

[0239] According to the projector described in Appendix 11, the first reflective film is a metal film that reflects the first light.

[0240] According to the structure in Appendix 14, the first reflective film is formed on the surface of a plate-shaped component made of high-precision glass, which easily ensures the optical properties of the first reflective film and achieves the weight reduction of the first light guide element.

[0241] Postscript 15

[0242] According to the projector described in Appendix 11, the first substrate has: a first surface facing the interior space of the first light guide element; and a second surface facing the exterior of the first light guide element and opposite to the first surface, wherein the first reflective film is disposed on the second surface, and the first reflective film is a metal film that reflects the first light.

[0243] According to the structure in Appendix 15, the first reflective film is formed on the surface of a plate-shaped component made of high-precision glass, which easily ensures the optical properties of the first reflective film, and achieves the weight reduction of the first light guide element, thereby increasing the design freedom of the first reflective film.

[0244] Postscript 16

[0245] The projector according to any one of Annexes 1 to 15, wherein the first light guide element has a rectangular cross-sectional shape and the second light guide element has a rectangular cross-sectional shape.

[0246] According to the structure in Appendix 16, it is easy to generate a first light and a second light with a uniform illuminance distribution in a rectangular shape as illumination light.

[0247] Postscript 17

[0248] The projector according to any one of Annexes 1 to 16, wherein the cross-sectional area of ​​the first emitting end is greater than the cross-sectional area of ​​the first incident end, and the cross-sectional area of ​​the second emitting end is greater than the cross-sectional area of ​​the second incident end.

[0249] According to the structure in Appendix 17, 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.

[0250] Postscript 18

[0251] The projector according to any one of Appendix 1 to Appendix 4, wherein the length from the first incident end to the first exit end is 5 mm or more and 25 mm or less.

[0252] According to the structure in Appendix 18, 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.

[0253] Postscript 19

[0254] According to the projector described in Appendix 11, 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.

[0255] According to the structure in Appendix 19, 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: This projector features: The first light source emits the first light in the first wavelength band and the second light in the second wavelength band; The first light guide element has a first substrate and a first reflective film disposed on the first substrate, and has a first incident end and a first emission end. The first light and the second light emitted from the first light source are incident on the first incident end, and the first emission end emits the first light. The first optical modulation element modulates the light of the first band emitted from the first light guide element based on image information; as well as The projection optical system projects light emitted from the first optical modulation element. The first light guide element has a lower reflectivity for the second light than for the first light.

2. The projector according to claim 1, characterized in that, The projector also features: The second light source emits the third light in the third band and the fourth light in the fourth band; The third light source emits the fifth light in the fifth band and the sixth light in the sixth band; The second light guide element has a second substrate and a second reflective film disposed on the second substrate, and has a second incident end and a second emission end. The third light and the fourth light emitted from the second light source are incident on the second incident end, and the third light is emitted from the second emission end. The third light guide element has a third substrate and a third reflective film disposed on the third substrate, and has a third incident end and a third emission end. The fifth light and the sixth light emitted from the third light source are incident on the third incident end, and the fifth light is emitted from the third emission end. The second optical modulation element modulates the light of the third band emitted from the second light guide element based on image information; as well as The third optical modulation element modulates the fifth band of light emitted from the third light guide element based on image information. The second light guide element has a lower reflectivity for the fourth light than for the third light. The third light guide element has a lower reflectivity for the sixth light than for the fifth light.

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

4. The projector according to claim 1 or 2, characterized in that, The first light source converts the excitation light into fluorescence by irradiating the fluorescent layer, and then emits the fluorescence. The first light is the fluorescence converted from a portion of the excitation light. The second light is another part of the excitation light.

5. The projector according to claim 2, characterized in that, The first light is blue light. The third light is green light. The fifth light is red light.

6. The projector according to claim 2, characterized in that, The first band contains 467nm. The third band includes 532nm. The fifth band contains 630 nm.

7. The projector according to claim 1 or 2, characterized in that, The difference between the amount of light emitted from the first light source and the amount of light emitted from the first emission end is greater than the amount of light emitted from the first emission end.

8. The projector according to claim 1 or 2, characterized in that, The reflectivity of the first light guide element to the second light is lower than the transmittance of the first light guide element to the second light.

9. The projector according to claim 1 or 2, characterized in that, The reflectivity of the first light guide element to the second light is lower than the absorption rate of the first light guide element to the second light.

10. The projector according to claim 1 or 2, characterized in that, The reflectivity of the first light guide element to the second light is lower than the sum of the transmittance and absorptivity of the first light guide element to the second light.

11. The projector according to claim 8, characterized in that, The material of the first substrate is glass.

12. The projector according to claim 9, characterized in that, The first substrate is made of metal.

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

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

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

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

17. The projector according to claim 2, characterized in that, The cross-sectional area of ​​the first ejection end is larger than the cross-sectional area of ​​the first incident end. The cross-sectional area of ​​the second ejection end is larger than the cross-sectional area of ​​the second incident end.

18. The projector according to claim 1 or 2, characterized in that, The length from the first incident end to the first exit end is 5 mm or more and 25 mm or less.

19. The projector according to claim 1 or 2, characterized in that, The first incident end has a dimension along the long side of the opening through which the first light is incident. The size of the first incident end is 1 mm or more and 3 mm or less. The first emitting end has a dimension along the long side of the opening from which the first light is emitted. The size of the first ejection end is 14 mm or more and 16 mm or less.

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