projector

Abstract

We provide a projector that can improve the light utilization efficiency of the light source. [Solution] The projector of the present invention comprises a first light source that emits first light, a first light guide element having a first incident end and a first exit end, a first reflective polarizing element that transmits a first polarization component of the first light and reflects a second polarization component, a first light modulation element that modulates the first polarization component according to image information, and a projection optical system that projects the light emitted from the first light modulation element. The first reflective polarizing element has a first polarization transmission axis that transmits the first polarization component and a first polarization reflection axis that reflects the second polarization component. The cross-sectional shape of the first exit end is a rectangle having a pair of first long sides that face each other and a pair of first short sides that are perpendicular to the pair of first long sides and face each other. When viewed from above, the first polarization reflection axis is inclined with respect to the first long sides and the first short sides, respectively, and the first reflected light reflected by the first reflective polarizing element is incident on the first exit end of the first light guide element.

Description

Technical Field

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[0003]

[0001] The present invention relates to a projector.

Background Art

[0002] Conventionally, a projector including a light source that emits colored light, a light modulation device that modulates the colored light emitted from the light source according to image information to generate image light, and a projection optical system that enlarges and projects the image light emitted from the light modulation device onto a projection surface such as a screen is known. For example, the projector includes a light source device having a blue light source that emits blue light, an excitation light source that is provided separately from the blue light source and emits blue light, and a phosphor that is excited by the blue light emitted from the excitation light source and emits yellow light. In such a projector, white light including blue light and yellow light is emitted from the light source device, and each colored light included in the white light is converted into image light by a common light modulation device or light modulation devices arranged for each colored light.

[0003] ​​​​​​​​​​​​​​​​​​​​​​​​​​In the above-mentioned projector, the polarization component of the light incident from the light source that is not used for image generation in the optical modulation element becomes unwanted light, which leads to a problem in that the light utilization efficiency of the light source is reduced. [Means for solving the problem]

[0006] To solve the above problems, according to one aspect of the present invention, a first light guide element has a first light source that emits first light in a first wavelength band, a first incident end into which the first light emitted from the first light source is incident, and a first exit end that emits the first light, a first reflective polarizing element that transmits a first polarization component of the first light emitted from the first light guide element and reflects a second polarization component having a polarization direction different from that of the first polarization component, a first light modulation element that modulates the first polarization component of the first light emitted from the first reflective polarizing element according to image information, and a projection optical system that projects the light emitted from the first light modulation element, wherein the first reflective polarizing element is A projector is provided, having a first polarization transmission axis for transmitting a first polarization component and a first polarization reflection axis for reflecting a second polarization component, wherein the cross-sectional shape of the first exit end in a plane perpendicular to a first optical axis passing through the center of the first incident end and the center of the first exit end is a rectangle having a pair of opposing first long sides and a pair of opposing first short sides perpendicular to the pair of first long sides, and when viewed in plan along the first optical axis, the first polarization reflection axis is inclined with respect to the first long sides and the first short sides, respectively, and the first reflected light reflected by the first reflection polarizing element is incident on the first exit end of the first light guide element. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram showing the configuration of a projector in one embodiment. [Figure 2] This diagram shows the positions of the first light guide element and the first incident polarizing element. [Figure 3] This figure shows how the polarization direction of the reflected light from the first incident polarizing element changes. [Figure 4]This figure shows the positions of the first light guide element and the first incident polarizing element in the comparative example. [Figure 5] This figure shows how the polarization direction of the blue reflected light changes in the comparative example. [Figure 6] This diagram shows the positional relationship between the second light guide element and the second incident polarizing element. [Modes for carrying out the invention]

[0008] One embodiment of the present invention will be described below with reference to the drawings. In the following drawings, the dimensions of each component may be shown on a different scale to make them easier to see.

[0009] Figure 1 is a schematic diagram showing the configuration of a projector 100 according to one embodiment of the present invention. The projector 100 is an image display device equipped with three liquid crystal panels as an optical modulation device, and is a so-called three-panel projector. As shown in Figure 1, the projector 100 comprises an image forming module 10 and a projection optical system 20.

[0010] The image forming module 10 includes a blue light source (first light source) 11, a red light source (second light source) 12, a green light source (third light source) 13, a blue illumination optical system 16, a red illumination optical system 17, a green illumination optical system 18, a blue light modulator 21, a red light modulator 22, a green light modulator 23, and a photosynthesis element 30.

[0011] The blue light source 11 emits blue light (first light) LB. In the following description, the direction parallel to the optical axis of the blue light LB emitted from the blue light source 11 is referred to as the D1 direction. One side in the D1 direction is referred to as the -D1 side, and the side opposite to the -D1 side in the D1 direction is referred to as the +D1 side. The direction perpendicular to the D1 direction within the plane containing the optical axis of the blue light LB is referred to as the D2 direction. One side in the D2 direction is referred to as the -D2 side, and the side opposite to the -D2 side in the D2 direction is referred to as the +D2 side. The direction perpendicular to both the D1 and D2 directions is referred to as the D3 direction. The blue light LB emitted from the blue light source 11 travels along the D1 direction towards the +D1 side.

[0012] The blue light source 11 comprises a substrate 11a and a blue light-emitting element 11b supported on the substrate 11a. The substrate 11a is made of, for example, metal and also acts as a heat dissipation member, receiving heat from the blue light-emitting element 11b that emits blue light LB and releasing that heat into the external space. The blue light-emitting element 11b is provided on the +D1 side of the substrate 11a, which is a plate surface parallel to the plane including the D2 and D3 directions. The blue light-emitting element 11b emits blue light LB in the blue wavelength band of the visible wavelength band. The blue wavelength band corresponds to the first wavelength band. The blue light LB corresponds to the first light. The light-emitting surface of the blue light-emitting element 11b is arranged substantially parallel to the plane including the D2 and D3 directions, and is the surface on the blue light-emitting element 11b opposite in the D1 direction to the surface of the substrate 11a that faces the +D1 side. The blue light LB diverges from the light-emitting surface of the blue light-emitting element 11b, passing through the center of the light-emitting surface of the blue light-emitting element 11b and around an axis parallel to the D1 direction, according to a predetermined radiation angle, and is emitted towards the +D1 side. The blue wavelength band is, for example, the wavelength band of 420 nm to 500 nm.

[0013] The blue light-emitting element 11b is composed of, for example, an LED that emits blue light LB. The blue light-emitting element 11b may consist of a single LED or of multiple LEDs. When the blue light-emitting element 11b is composed of multiple LEDs, the multiple LEDs are arranged in the region occupied by the blue light-emitting element 11b in a plane including the D2 and D3 directions.

[0014] The blue illumination optical system 16 generates blue illumination light B from blue light LB emitted from the blue light source 11. The blue illumination optical system 16 includes a first light guide element 161 and a first parallelizing element 162. The first light guide element 161 has a first incident end 161a into which blue light LB emitted from the blue light source 11 is incident, a first exit end 161b that emits blue light LB from the +D1 side, and a first side surface 161s and a first reflective surface 161r that extend between the first incident end 161a and the first exit end 161b in the D1 direction. The first light guide element 161 has a first optical axis 160 that passes through the center of the first incident end 161a and the center of the first exit end 161b.

[0015] The first incident end 161a extends parallel to the plane including the D2 and D3 directions. The shape of the first incident end 161a when viewed from the D1 direction is similar to the shape of the light-emitting surface of the blue light-emitting element 11b when viewed from the same direction, and is, for example, rectangular.

[0016] The first exit end 161b extends parallel to the plane including the D2 and D3 directions and is larger than the first entrance end 161a. The shape of the first exit end 161b when viewed from the D1 direction is similar to the shape of the modulation surface of the first optical modulation element 210 of the blue light modulation device 21 when viewed from the same direction, and is similar to the modulation surface of the first optical modulation element 210, for example, being rectangular. The size of the first exit end 161b in the plane including the D2 and D3 directions is equivalent to the size of the modulation surface of the first optical modulation element 210 in the plane including the D2 and D3 directions. The first side surface 161s and the first reflective surface 161r connect the periphery of the first entrance end 161a and the periphery of the first exit end 161b in the D1 direction.

[0017] The blue light LB emitted from the blue light source 11 enters the first light guide element 161 from the first incident end 161a. The first light guide element 161 equalizes the in-plane illuminance of the blue light LB as will be described later. In the first light guide element 161, the region surrounded by the first incident end 161a, the first emission end 161b, and the first reflection surface 161r is the region through which the blue light LB propagates. The size in the plane including the D2 direction and the D3 direction of the region surrounded by the first incident end 161a, the first emission end 161b, and the first reflection surface 161r increases as it progresses from the -D1 side to the +D1 side in the D1 direction. Further, the shape of the region surrounded by the first incident end 1,61a, the first emission end 161b, and the first reflection surface 161r in the plane including the D2 direction and the D3 direction changes from the shape of the light emitting surface of the blue light emitting element 11b as viewed in the D1 direction to the shape of the modulation surface of the first light modulation element 210 as it progresses from the -D1 side to the +D1 side.

[0018] The first side surface 161s of the first light guide element 161 and the first reflection surface 161r provided on the first side surface 161s as will be described later form a predetermined angle with respect to the first optical axis 160 and move away from the virtual line in the plane including the D2 direction and the D3 direction as it moves from the -D1 side to the +D1 side. The blue light LB incident on the first light guide element 161 propagates from the -D1 side to the +D1 side within the region surrounded by the first incident end 161a, the first emission end 161b, and the first reflection surface 161r.

[0019] In the case of the present embodiment, the shape of the modulation surface of the first light modulation element 210 as viewed along the D1 direction is rectangular, and the shape of the light emitting surface of the blue light emitting element 11b as viewed along the D1 direction is substantially similar to the modulation surface of the first light modulation element 210 and is rectangular.

[0020] A part of the blue light LB incident on the first light guide element 161 propagates directly from the first incident end 161a to the first emission end 161b along a direction forming an angle smaller than a predetermined angle with respect to the first optical axis 160 without being incident on the first reflection surface 161r even once. The remaining part of the blue light LB incident on the first light guide element 161 forms an angle greater than or equal to a predetermined angle with respect to the first optical axis 160, is incident on the first reflection surface 161r one or more times from the first incident end 161a, and reaches the first emission end 161b after being reflected by the first reflection surface 161r. The path of the light rays of the blue light LB within the region surrounded by the first incident end 161a, the first emission end 161b, and the first reflection surface 161r varies according to the incident angle on the first incident end 161a and extends to a plurality of paths with different numbers of reflections on the first reflection surface 161r. From this, the illuminance distribution of the blue light LB propagating through the region surrounded by the first incident end 161a, the first emission end 161b, and the first reflection surface 161r is uniformized within the plane including the D2 direction and the D3 direction. That is, the first light guide element 161 uniformizes the illuminance distribution of the incident blue light LB within the plane including the D2 direction and the D3 direction. The blue light LB with the uniformized illuminance distribution is emitted from the first emission end 161b to the +D1 side.

[0021] In the first light guide element 161 of the present embodiment, the reflectivity of the first reflection surface 161r with respect to the blue light LB is constant regardless of the polarization direction. For example, the reflectivity of the first reflection surface 161r with respect to the first polarization component LBp of the blue light LB, which will be described later, is 80% or more, and the reflectivity of the first reflection surface 161r with respect to the second polarization component LBs of the blue light LB, which will be described later, is 80% or more. According to this configuration, since the first reflection surface 161r efficiently reflects the blue light LB regardless of the polarization direction, the effect of improving the light utilization efficiency of the blue light LB, which will be described later, can be enhanced.

[0022] The first light guide element 161 is a reflector made of a transparent material such as optical glass. The reflector has a frame and is formed as a hollow member. When viewed along the D1 direction, the -D1 end of the reflector frame has the same shape as the first incident end 161a and the light-emitting surface of the blue light-emitting element 11b, and is formed to the same size as the light-emitting surface of the blue light-emitting element 11b, for example, in the shape of a rectangular frame. The +D1 end of the reflector frame has the same shape and size as the first exit end 161b and the modulation surface of the first light modulation element 210, and is formed to the same size as, for example, a rectangular frame with a different size from the -D1 end.

[0023] The reflector is composed of plate-shaped members made of, for example, a transparent material. As described above, the shape of the first incident end 161a and the first exit end 161b when viewed from the D1 direction is rectangular, so the reflector is composed of four trapezoidal plate-shaped members. The length of the side parallel to the D2 or D3 direction on the -D1 side, which corresponds to the upper base of the four plate-shaped members, is set according to the size of the first incident end 161a and the light-emitting surface of the blue light-emitting element 11b in the D2 or D3 direction. The length of the side parallel to the D2 or D3 direction on the +D1 side, which corresponds to the lower base of the four plate-shaped members, is set according to the size of the first exit end 161b and the modulation surface of the first light modulation element 210 in the D2 or D3 direction. Of the four plate-shaped members, one side of one of the two plate-shaped members, which corresponds to one leg, is connected to the side of the other plate-shaped member, which corresponds to the other leg.

[0024] As described above, if the reflector of the first light guide element 161 is made of a plate-shaped member made of a transparent material, the first side surface 161s, that is, the plate surface of the plate-shaped member facing the external space of the reflector, acts as a reflective surface. In the reflector of the first light guide element 161, in order to increase the reflectivity of the blue light LB incident on the first light guide element 161 from the first incident end 161a near the first side surface 161s, a reflective film 151 made of a dielectric multilayer film or the like is provided on the plate surface of the plate-shaped member constituting the reflector that is opposite to the first side surface 161s, that is, on the inner surface of the plate-shaped member. In this case, the plate surface constituting the inner surface of the reflector in the plate-shaped member acts as the first reflective surface 161r. A portion of the blue light LB incident on the inside of the reflector of the first light guide element 161 from the first incident end 161a is reflected by the reflective film 151 and propagates toward the +D1 side. In addition, in the first light guide element 161, a reflective film 151 may be formed on the plate-shaped member constituting the reflector that faces the external space of the reflector, thereby causing it to act as the first reflective surface 161r.

[0025] The first parallelizing element 162 is, for example, a plano-convex lens and is positioned on the optical path of the blue light LB emitted from the first light guide element 161. The first parallelizing element 162 parallelizes the blue light LB emitted from the first light guide element 161 along the D1 direction. The first parallelizing element 162 is in contact with the first exit end 161b of the first light guide element 161. By the first parallelizing element 162 being in contact with the first exit end 161b, the blue light LB emitted from the first exit end 161b of the first light guide element 161 is efficiently captured by the first parallelizing element 162, and the loss of blue light LB is suppressed. However, the first parallelizing element 162 may be an optical lens other than a plano-convex lens capable of parallelizing the incident blue light LB. Also, the first parallelizing element 162 may be arranged at an appropriate distance from the first light guide element 161 in the D1 direction.

[0026] The blue light modulator 21 modulates the blue illumination light B emitted from the first parallelizing element 162 of the blue illumination optical system 16 according to image information. The blue light modulator 21 includes a first light modulator 210, a first incident polarizer 211, and a first exit polarizer 212.

[0027] The first incident polarizing element (first reflective polarizing element) 211 is provided on the optical path of the blue light LB emitted from the first parallelizing element 162 and is positioned on the +D1 side of the first parallelizing element 162. In this embodiment, the first incident polarizing element 211 is in contact with the first optical modulation element 210 from the -D1 side, but it may be positioned at an appropriate distance from the first optical modulation element 210 in the D1 direction.

[0028] The first incident polarizing element 211 corresponds to an example of the first reflective polarizing element of the present invention, and is, for example, a reflective polarizing plate having a plate surface parallel to the plane including the D2 direction and D3 direction. The first incident polarizing element 211 transmits the first polarization component LBp of the blue light LB emitted from the first parallelizing element 162 and emits it towards the +D1 side along the D1 direction. The first incident polarizing element 211 also reflects the second polarization component LBs of the blue light LB emitted from the first parallelizing element 162 and emits it towards the -D1 side along the D1 direction. The first polarization component LBp corresponds to P polarization, and the second polarization component LBs corresponds to S polarization.

[0029] The first optical modulation element 210 is positioned on the optical path of the first polarization component LBp of the blue light LB emitted from the first incident polarizing element 211. The first optical modulation element 210 modulates the first polarization component LBp of the blue light LB emitted from the first incident polarizing element 211 based on image information input from an image forming apparatus such as a computer (not shown) connected to the first optical modulation element 210 from the outside. The first optical modulation element 210 is, for example, a transmissive liquid crystal panel. The liquid crystal panel constituting the first optical modulation element 210 has a plurality of pixels (not shown). Each pixel is equipped with a switching element. Each pixel modulates the vibration direction of the blue light LB incident from the first incident polarizing element 211 by the operation of the switching element in accordance with the electrical signal that generates the blue image, thereby generating blue image light IB. The first optical modulation element 210 emits the image light IB generated by the liquid crystal panel along the D1 direction toward the +D1 side.

[0030] The first emission-side polarizing element 212 is provided on the optical path of the image light IB emitted from the first optical modulation element 210 and is positioned on the +D1 side of the first optical modulation element 210. In this embodiment, the first emission-side polarizing element 212 is in contact with the first optical modulation element 210 from the +D1 side, but it may also be positioned at an appropriate distance from the first optical modulation element 210 in the D1 direction. The first emission-side polarizing element 212 emits a predetermined polarization of the image light IB emitted from the first optical modulation element 210 along the D1 direction toward the +D1 side. The predetermined polarization is, for example, S polarization.

[0031] The first exit-side polarizing element 212 is, for example, a reflective polarizer or an absorbing polarizer having a plate surface parallel to the planes including the D2 and D3 directions. The first exit-side polarizing element 212 transmits a predetermined polarization of the incident image light IB to the +D1 side and reflects or absorbs other polarizations of the image light IB. By employing an absorbing polarizer as the first exit-side polarizing element 212, reflected light and stray light to the first optical modulation element 210 can be suppressed.

[0032] The red light source 12 emits red light (secondary light) LR. The red light LR emitted from the red light source 12 travels along the D1 direction toward the -D1 side. The red light source 12 has the same configuration as the blue light source 11, except that the color of the light it emits is different. For this reason, the explanation of the configuration of the red light source 12 will be omitted or simplified.

[0033] The red light source 12 comprises a substrate 12a and a red light-emitting element 12b supported on the substrate 12a. The red light-emitting element 12b is provided on the -D1 side surface of the substrate 12a, which is parallel to the plane including the D2 and D3 directions. The red light-emitting element 12b corresponds to an example of the second light-emitting element of the present invention and emits red light LR in the red wavelength band of the visible wavelength band. The red wavelength band corresponds to the second wavelength band. The red light LR corresponds to the second light. The light-emitting surface of the red light-emitting element 12b is arranged substantially parallel to the plane including the D2 and D3 directions, and is the surface opposite in the D1 direction to the surface of the substrate 12a facing the -D1 side surface of the red light-emitting element 12b. The red light LR diverges from the light-emitting surface of the red light-emitting element 12b, passing through the center of the light-emitting surface of the red light-emitting element 12b and around an axis parallel to the D1 direction, according to a predetermined radiation angle, and is emitted towards the -D1 side. The red wavelength band is, for example, the wavelength band of 610 nm to 700 nm.

[0034] The red light-emitting element 12b is composed of, for example, an LED that emits red light (LR). The red light-emitting element 12b may consist of a single LED or of multiple LEDs combined.

[0035] The red illumination optical system 17 generates red illumination light R from red light LR emitted from the red light source 12. The red illumination optical system 17 includes a second light guide element 171 and a second parallelizing element 172. The second light guide element 171 has a second incident end 171a into which red light LR emitted from the red light source 12 is incident, a second exit end 171b that emits red light LR from the -D1 side, and a second side surface 171s and a second reflective surface 171r that extend between the second incident end 171a and the second exit end 171b in the D1 direction. The second light guide element 171 has a second optical axis 170 that passes through the center of the second incident end 171a and the center of the second exit end 171b. The shape of the second incident end 171a is a rectangle, similar to the shape of the light-emitting surface of the red light-emitting element 12b when viewed from the D1 direction. The shape of the second exit end 171b is a rectangle, similar to the modulation surface of the second optical modulation element 220.

[0036] The red light LR emitted from the red light source 12 enters the second light guide element 171 from the second incident end 171a. The size of the propagation region of the red light LR enclosed by the second incident end 171a, the second exit end 171b, and the second reflective surface 171r in the plane including the D2 and D3 directions increases as the light progresses from the +D1 side to the -D1 side in the D1 direction.

[0037] The second side surface 171s of the second light guide element 171, and the second reflective surface 171r provided on the second side surface 171s, form a predetermined angle with respect to the second optical axis 170, and move away from the imaginary line in a plane including the D2 and D3 directions as the light moves from the +D1 side to the -D1 side. The second light guide element 171 equalizes the illuminance distribution of the incident red light LR in a plane including the D2 and D3 directions. The red light LR with the equalized illuminance distribution is emitted from the second emission end 171b towards the -D1 side.

[0038] The second light guide element 171, like the first light guide element 161, is a hollow reflector composed of a plate-shaped member made of a transparent material such as optical glass. The reflector of the second light guide element 171 acts as a second reflective surface 171r by providing a reflective film 152 made of a dielectric multilayer film or the like on the inner surface of the plate-shaped member. In addition, in the second light guide element 171, the reflective film 152 may be formed on the plate-shaped member constituting the reflector that faces the external space of the reflector, thereby making it act as a second reflective surface 171r.

[0039] The second parallelizing element 172 is, for example, a plano-convex lens, and parallelizes the red light LR emitted from the second light guide element 171 along the D1 direction. By contacting the second emission end 171b of the second light guide element 171, the second parallelizing element 172 efficiently captures the red light LR and suppresses the loss of red light LR. Note that the second parallelizing element 172 may be an optical lens other than a plano-convex lens, as long as it can parallelize the red light LR. Also, the second parallelizing element 172 may be positioned at an appropriate distance from the second light guide element 171 in the D1 direction.

[0040] The red light modulator 22 modulates the red illumination light R emitted from the second parallelizing element 172 of the red illumination optical system 17 according to image information. The red light modulator 22 includes a second light modulator 220, a second incident polarizing element (second reflective polarizing element) 221, and a second exit polarizing element 222, all of which are arranged in contact with each other.

[0041] The second incident polarizing element 221 corresponds to an example of the second reflective polarizing element of the present invention, and is, for example, a reflective polarizing plate having a plate surface parallel to the plane including the D2 direction and D3 direction. The second incident polarizing element 221 transmits the third polarization component LRp of the red light LR emitted from the second parallelizing element 172 and emits it to the -D1 side along the D1 direction. The second incident polarizing element 221 also reflects the fourth polarization component LRs of the red light LR emitted from the second parallelizing element 172 and emits it to the +D side along the D1 direction. The third polarization component LRp corresponds to P polarization, and the fourth polarization component LRs corresponds to S polarization.

[0042] The second optical modulator 220 is positioned on the optical path of the third polarization component LRp of the red light LR emitted from the second incident polarizing element 221. The second optical modulator 220 modulates the third polarization component LRp of the red light LR emitted from the second incident polarizing element 221 based on image information input from an image forming apparatus, such as a computer (not shown), which is connected to the second optical modulator 220 from the outside. The second optical modulation element 220 is, for example, a transmissive liquid crystal panel. The liquid crystal panel constituting the second optical modulation element 220 has a plurality of pixels (not shown). Each pixel is equipped with a switching element. Each pixel modulates the third polarization component LRp incident from the second incident polarizing element 221 by the operation of the switching element in accordance with the electrical signal that generates the red image, thereby generating red image light IR. The second optical modulation element 220 emits the image light IR generated by the liquid crystal panel along the D1 direction toward the -D1 side.

[0043] The second emission polarizing element 222 is positioned on the optical path of the image light IR emitted from the second optical modulation element 220. The second emission polarizing element 222 emits a predetermined polarization component of the image light IR emitted from the second optical modulation element 220 along the D1 direction toward the -D1 side. The predetermined polarization component is, for example, S polarization.

[0044] The second exit-side polarizing element 222 is, for example, a reflective polarizer or an absorbing polarizer having a plate surface parallel to the planes including the D2 and D3 directions. The second exit-side polarizing element 222 transmits a predetermined polarization of the incident image light IR to the -D1 side and reflects or absorbs other polarizations of the image light IR. By employing an absorbing polarizer as the second exit-side polarizing element 222, reflected light and stray light to the second optical modulation element 220 can be suppressed.

[0045] The green light source 13 emits green light (third light) LG along the D2 direction towards the +D2 side. The green light source 13, like the blue light source 11 and the red light source 12, has a substrate 13a and a green light-emitting element 13b. The green light-emitting element 13b is provided on the +D2 side surface of the substrate 13a, which is parallel to the plane including the D1 and D3 directions. The green light-emitting element 13b emits green light LG in the green wavelength band of the visible wavelength band. The light-emitting surface of the green light-emitting element 13b is arranged substantially parallel to the plane including the D1 and D3 directions, and is the surface on the green light-emitting element 13b opposite in the D2 direction to the surface in contact with the +D2 side surface of the substrate 13a. The green light LG diverges from the light-emitting surface of the green light-emitting element 13b around an axis parallel to the D2 direction passing through the center of the light-emitting surface of the green light-emitting element 13b, according to a predetermined radiation angle, and is emitted towards the +D2 side. The green wavelength band is, for example, the wavelength range of 500 nm to 600 nm. The green light-emitting element 13b is composed of, for example, an LED that emits green light LG. The green light-emitting element 13b may consist of a single LED or of multiple LEDs combined.

[0046] In this embodiment, the green light-emitting element 13b generates green light LG through fluorescence generated by a green phosphor. On the other hand, the blue light-emitting element 11b and the red light-emitting element 12b both generate blue light LB and red light LR without using fluorescence. In other words, the green light source 13 has a phosphor, while the blue light source 11 and the red light source 12 do not. The differences that arise from the presence or absence of phosphors in each light source 11, 12, and 13 will be described later.

[0047] The green illumination optical system 18 generates green illumination light G from green light LG emitted from the green light source 13. The green illumination optical system 18 includes a third light guide element 181 and a third parallelizing element 182. The third light guide element 181 has a third incident end 181a, a third exit end 181b, a third side surface 181s, and a third reflective surface 181r. The third light guide element 181 has a third optical axis 180 passing through the center of the third incident end 181a and the center of the third exit end 181b. The shape of the third incident end 181a is a rectangle similar to the shape of the light-emitting surface of the green light-emitting element 13b when viewed from the D2 direction. The shape of the third exit end 181b is a rectangle similar to the modulation surface of the third light modulation element 230.

[0048] The size of the propagation region of the green light LG, enclosed by the third incident end 181a, the third exit end 181b, and the third reflecting surface 181r, in the plane including the D1 and D3 directions, increases as it progresses from the -D2 side to the +D2 side in the D2 direction.

[0049] The third side surface 181s of the third light guide element 181, and the third reflective surface 181r provided on the third side surface 181s, form a predetermined angle with respect to the third optical axis 180, and move away from the imaginary line in the plane including the D1 and D2 directions as moving from the -D2 side to the +D2 side. The third light guide element 181 equalizes the illuminance distribution of the incident green light LG in the plane including the D1 and D2 directions. The green light LG with the equalized illuminance distribution is emitted from the third emission end 181b towards the +D2 side.

[0050] The third light guide element 181, like the first light guide element 161 and the second light guide element 171, is a hollow reflector composed of a plate-shaped member made of a transparent material such as optical glass. The reflector of the third light guide element 181 acts as a third reflective surface 181r by providing a reflective film 153 made of a dielectric multilayer film or the like on the inner surface of the plate-shaped member. In addition, in the third light guide element 181, the reflective film 153 may be formed on the plate surface of the plate-shaped member constituting the reflector that faces the external space of the reflector, thereby making it act as a third reflective surface 181r.

[0051] The third parallelizing element 182 is, for example, a plano-convex lens, and parallelizes the green light LG emitted from the third light guide element 181 along the D2 direction. The third parallelizing element 182 efficiently captures the green light LG by contacting the third emission end 181b of the third light guide element 181, thereby suppressing the loss of green light LG. The third parallelizing element 182 may be an optical lens other than a plano-convex lens, as long as it can parallelize the green light LG. Also, the third parallelizing element 182 may be positioned at an appropriate distance from the third light guide element 181 in the D2 direction.

[0052] The green light modulator 23 modulates the green illumination light G emitted from the third parallelizing element 182 of the green illumination optical system 18 according to image information. The green light modulator 23 includes a third light modulator 230, a third incident polarizing element (third reflective polarizing element) 231, and a third emission polarizing element 232, all arranged in contact with each other. A predetermined polarization component of the green light LG emitted from the third parallelizing element 182 is emitted along the D2 direction towards the +D2 side. The predetermined polarization component is, for example, S polarization.

[0053] The third incident polarizing element 231 corresponds to an example of the third reflective polarizing element of the present invention, and is, for example, a reflective polarizing plate having a plate surface parallel to the plane including the D1 direction and the D3 direction. The third incident polarizing element 231 transmits the fifth polarization component LGp of the incident green light LG and emits it to the +D2 side along the D2 direction. The third incident polarizing element 231 also reflects the sixth polarization component LGs of the incident green light LG and emits it to the -D2 side along the D2 direction. The fifth polarization component LGp corresponds to P polarization, and the sixth polarization component LGs corresponds to S polarization.

[0054] The third optical modulation element 230 modulates the fifth polarization component LGp of the blue light LB emitted from the third incident polarizing element 231 based on image information input from an external source. The third optical modulation element 230 is, for example, a transmissive liquid crystal panel. The liquid crystal panel constituting the third optical modulation element 230 has multiple pixels, and each pixel is equipped with a switching element. Each pixel modulates the vibration direction of the green light LG incident from the third incident polarizing element 231 by the operation of the switching element in accordance with the electrical signal that generates the green image, thereby generating green image light IG. The third optical modulation element 230 emits the image light IG generated by the liquid crystal panel along the D2 direction towards the +D1 side.

[0055] The third output polarizing element 232 outputs a predetermined polarization component of the image light IG emitted from the third optical modulation element 230 along the D2 direction to the +D2 side. The predetermined polarization component is, for example, P polarization. The third output polarizing element 232 is, for example, a reflective polarizer or an absorbing polarizer, which transmits the predetermined polarization component of the incident image light IG to the +D2 side and reflects or absorbs other polarization components of the image light IG. By using an absorbing polarizer as the third output polarizing element 232, it is possible to suppress reflected light and stray light to the third optical modulation element 230.

[0056] The photosynthesis element 30 is positioned in the region where the optical paths of the image light IB, IR, and IG emitted from the blue light modulator 21, the red light modulator 22, and the green light modulator 23 intersect. The photosynthesis element 30 synthesizes the image light IB, IR, and IG and emits the resulting image light IM along the D2 direction towards the +D2 side.

[0057] The photosynthetic element 30 is, for example, a cross dichroic prism 31. The cross dichroic prism 31 is constructed by aligning the right-angle vertices of four right-angle prisms at the center of the photosynthetic element 30 and bonding the right-angle surfaces together when viewed from the D3 direction, and includes two reflective films 32 and 33.

[0058] The reflective film 32 is positioned such that, when viewed along the D3 direction, it moves from the +D2 side to the -D2 side as it moves from the -D1 side to the +D1 side. The reflective film 33 is positioned such that, when viewed along the D3 direction, it moves from the -D2 side to the +D2 side as it moves from the -D1 side to the +D1 side. The reflective film 32 has optical properties that reflect light in the red wavelength band and transmit light in the blue wavelength band and the green wavelength band. The reflective film 33 has optical properties that reflect light in the blue wavelength band and transmit light in the green wavelength band and the red wavelength band.

[0059] The S-polarized blue image light IB emitted from the first exit polarizing element 212 enters the cross dichroic prism 31, passes through the reflective film 32, is reflected by the reflective film 33, and travels to the +D2 side. The P-polarized green image light IG emitted from the third exit polarizing element 232 enters the cross dichroic prism 31, passes through the reflective films 32 and 33, and travels straight to the +D2 side. The S-polarized red image light IR emitted from the second exit polarizing element 222 enters the cross dichroic prism 31, passes through the reflective film 33, is reflected by the reflective film 32, and travels to the +D2 side. The image lights IB, IG, and IR emitted from the reflective films 32 and 33 of the cross dichroic prism 31 to the +D2 side are combined to generate a full-color image light IM. The cross dichroic prism 31 emits full-color image light IM along the D2 direction towards the +D2 side.

[0060] The projection optical system 20 is positioned on the optical path of the image light IM emitted from the photosynthetic element 30 of the image forming module 10. The projection optical system 20 projects the image light IM onto a screen SCR located +D2 side of the projection optical system 20, and displays the image light IM on the screen SCR in an enlarged view.

[0061] The projection optical system 20 is composed of, for example, 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, meniscus lenses, aspherical lenses, free-form lenses, and the like.

[0062] Incidentally, to make the projected image of the projector brighter, it is effective to increase the utilization efficiency of the light emitted from each light source 11, 12, and 13. In this embodiment, the projector 100 increases the utilization efficiency of each color light LB, LG, and LR by efficiently directing the respective color lights LB, LG, and LR emitted from each light source 11, 12, and 13 onto the light modulation elements 210, 220, and 230.

[0063] As described above, the blue light LB emitted from the blue light source 11 passes through the first incident polarizing element 211 and is incident on the first optical modulation element 210, so a portion of the blue light LB is reflected by the first incident polarizing element 211. The component reflected by the first incident polarizing element 211 is incident on the first optical guide element 161 via the first parallelizing element 162.

[0064] In the projector 100 of this embodiment, the blue light LB reflected by the first incident polarizing element 211 is returned to the first incident polarizing element 211 with a changed polarization direction, so that a portion of the re-incident blue light LB is recycled as image light IB generated by the first optical modulation element 210 after passing through the first incident polarizing element 211. The structure for recycling the blue light LB reflected by the first incident polarizing element 211 as image light IB will be described below.

[0065] Figure 2 shows the positional relationship between the first light guide element 161 and the first incident polarizing element 211. Figure 2 is a plan view of the first exit end 161b of the first light guide element 161 toward the -D1 side, with the first incident polarizing element 211 superimposed on it. For clarity, the first parallelizing element 162 is omitted from the illustration.

[0066] As shown in Figure 2, the first incident polarizing element 211 has a first polarization transmission axis TX that transmits the first polarization component LBp of the blue light LB, and a first polarization reflection axis RX that reflects the second polarization component LBs of the blue light LB. The first polarization transmission axis TX and the first polarization reflection axis RX are orthogonal to each other.

[0067] The blue light LB emitted from the blue light source 11 is unpolarized light containing a mixture of a first polarization component LBp and a second polarization component LBs. Therefore, the first incident polarizing element 211 reflects half of the blue light LB incident from the blue light source 11 as the second polarization component LBs.

[0068] The first incident polarizing element 211 is designed to have a reflectance of 80% or more for the second polarization component LBs of the blue light LB. With this configuration, the second polarization component LBs is efficiently reflected by the first incident polarizing element 211, so that the second polarization component LBs can be efficiently reused as image light IB.

[0069] In the first light guide element 161 of this embodiment, the first exit end 161b corresponds to the region enclosed by the first reflective surface 161r. Therefore, the cross-sectional shape of the first exit end 161b in the plane including the D2 and D3 directions perpendicular to the first optical axis 160 is rectangular. The first exit end 161b has a pair of first long sides 61a that face each other, and a pair of first short sides 61b that are perpendicular to the pair of first long sides 61a and face each other. The pair of first long sides 61a are sides along the D2 direction and are arranged with a gap in the D3 direction. The pair of first short sides 61b are sides along the D3 direction and are arranged with a gap in the D2 direction.

[0070] In the projector 100 of this embodiment, the first incident polarizing element 211 is positioned relative to the first light guide element 161 such that the first polarization transmission axis TX and the first polarization reflection axis RX and the first long side portion 61a and the first short side portion 61b satisfy predetermined conditions. Specifically, as shown in Figure 2, when viewed in plan along the first optical axis 160, the first polarization reflection axis RX is tilted with respect to the first long side portion 61a and the first short side portion 61b, respectively. It can also be said that the first polarization transmission axis TX is tilted with respect to the first long side portion 61a and the first short side portion 61b, respectively.

[0071] The angle θ between the first polarization reflection axis RX and the direction D3 along the first long side portion 61a is set to 15° to 75°. In the case of the projector 100 of this embodiment, the angle θ was set to 45°. Setting the angle within this range makes it possible to effectively change the polarization direction of the blue light LB when the blue light LB reflected by the first incident polarizing element 211 enters the first light guide element 161 and is reflected by the first reflective surface 161r, as described later.

[0072] Figure 3 shows how the polarization direction of the reflected blue light LB reflected by the first incident polarizing element 211 changes. Hereinafter, the second polarization component LBs of the blue light LB reflected by the first incident polarizing element 211 will be referred to as the blue reflected light (first reflected light) LB1.

[0073] As shown in Figure 3, the polarization direction of the blue reflected light LB1 in the first state J1 after reflection by the first incident polarizing element 211 coincides with the first polarization reflection axis RX. In other words, the first polarization direction H1 of the blue reflected light LB1 in the first state J1 is the direction indicated by the double arrow, which moves from the -D3 side to the +D3 side as it moves from the -D2 side to the +D2 side in a plane including the D2 and D3 directions.

[0074] The blue reflected light LB1 reflected by the first incident polarizing element 211 is incident on the first exit end 161b of the first light guide element 161. Therefore, the blue reflected light LB1 in the first state J1 moves toward the -D1 side and is reflected by the first reflective surface 161r of the first light guide element 161. For the sake of simplicity, let's assume that the blue reflected light LB1 is incident on the first reflective surface 161r at a 45° angle. Reflected by the first reflective surface 161r, it moves toward the -D2 side. In the second state J2 after reflection by the first reflective surface 161r, the second polarization direction H2 of the blue reflected light LB1 changes in the direction indicated by the double arrow, moving from the -D3 side toward the +D3 side as it moves from the -D1 side toward the +D1 side in a plane including the D1 and D3 directions.

[0075] In the second state J2, the blue reflected light LB1 moves toward the -D2 side and is incident on the first reflective surface 161r of the first light guide element 161 at a 45° angle. As a result, the third polarization direction H3 of the blue reflected light LB1 in the third state J3, after being reflected again by the first reflective surface 161r, changes in the direction indicated by the double arrow, moving from the +D3 side toward the -D3 side as it moves from the -D2 side toward the +D2 side within the plane including the D2 and D3 directions.

[0076] Here, the third polarization direction H3 of the blue reflected light LB1 in the third state J3 is perpendicular to the first polarization direction H1 of the blue reflected light LB1 in the first state J1. Since the third polarization direction H3 is perpendicular to the first polarization reflection axis RX, it is in the same direction as the first polarization transmission axis TX. In this way, the blue reflected light LB1 that is guided through the inside of the first light guide element 161 and then emitted from the first exit end 161b contains a first polarization component LBp that is transmitted through the first incident polarizing element 211.

[0077] Therefore, as shown in Figure 3, in the projector 100 of this embodiment, the blue reflected light LB1 reflected by the first incident polarizing element 211 is converted into a polarized component that passes through the first incident polarizing element 211 during the process of guiding it through the inside of the first light guide element 161.

[0078] Here, we will describe a comparative example with respect to the projector 100 of this embodiment. Figure 4 shows the positional relationship between the first light guide element 161 and the first incident polarizing element 1211 in the comparative example projector. Figure 4 corresponds to Figure 2. As shown in Figure 4, in the case of the comparative example's first incident polarizing element 1211, when viewed in plan along the first optical axis 160, the first polarization reflection axis RX0 is not tilted with respect to the first long side portion 61a and the first short side portion 61b. Also, the first polarization transmission axis TX0 is not tilted with respect to the first long side portion 61a and the first short side portion 61b. More specifically, the first polarization reflection axis RX0 is aligned with the first short side portion 61b and is perpendicular to each of the pair of first long side portions 61a. Also, the first polarization transmission axis TX0 is aligned with the first long side portion 61a and is perpendicular to each of the pair of first short side portions 61b.

[0079] In the comparative example, the second polarization component LBs of the blue light LB reflected by the first incident polarizing element 1211 is referred to as the blue reflected light LB2. Figure 5 shows how the polarization direction of the blue reflected light LB2 reflected by the first incident polarizing element 1211 of the comparative example changes. Figure 5 corresponds to Figure 3. As shown in Figure 5, the polarization direction of the blue reflected light LB2 in the first state J1 after reflection by the first incident polarizing element 1211 coincides with the first polarization reflection axis RX0. In other words, the first polarization direction H1 of the blue reflected light LB2 in the first state J1 is the direction indicated by the double arrow along the D3 direction.

[0080] The blue reflected light LB2 reflected by the first incident polarizing element 1211 is incident on the first exit end 161b of the first light guide element 161 and is reflected by the first reflective surface 161r. The second polarization direction H2 of the blue reflected light LB2 in the second state J2 after reflection by the first reflective surface 161r is the direction indicated by the double arrow along the D3 direction in a plane that includes the D1 and D3 directions.

[0081] In the second state J2, the blue reflected light LB2 travels toward the -D2 side and is reflected by the first reflective surface 161r of the first light guide element 161. In the third state J3, after being reflected again by the first reflective surface 161r, the third polarization direction H3 of the blue reflected light LB2 is the direction indicated by the double arrow along the D3 direction in a plane that includes the D2 and D3 directions.

[0082] Here, the third polarization direction H3 of the blue reflected light LB2 in the third state J3 is the same direction as the first polarization direction H1 of the blue reflected light LB2 in the first state J1. In other words, in the comparative example configuration, the blue reflected light LB2 emitted from the first exit end 161b after being guided through the first light guide element 161 remains as the second polarization component LBs and does not contain the first polarization component LBp that passes through the first incident polarizing element 211. Therefore, the blue reflected light LB2 reflected by the first incident polarizing element 1211 in the comparative example does not change its polarization direction even during the process of being guided through the first light guide element 161, and is therefore reflected again when it is incident on the first incident polarizing element 1211. Thus, the blue reflected light LB2 reflected by the first incident polarizing element 1211 in the comparative example cannot be recycled as image light IB generated by the first optical modulation element 210. Consequently, in the comparative example configuration, the light utilization efficiency of the blue light LB emitted from the blue light source 11 cannot be increased.

[0083] In contrast, in the case of the projector 100 of this embodiment, the blue reflected light LB1 reflected by the first incident polarizing element 211 can be converted into a first polarization component LBp that passes through the first incident polarizing element 211 during the process of guiding the light through the inside of the first light guide element 161.

[0084] In Figure 3, for the sake of simplicity, an example is given in which the blue reflected light LB1 changes from the second polarization component to the first polarization component by being reflected twice by the first reflective surface 161r of the first light guide element 161. The number of reflections by the first reflective surface 161r until the blue reflected light LB1 changes to the first polarization component varies depending on the angle of incidence to the first reflective surface 161r. However, it can be said that the component incident at an angle of 45° to the first reflective surface 161r is converted to the first polarization component by being reflected twice, as shown in Figure 3.

[0085] In the above description, a structure was given as an example in which the blue reflected light LB1 reflected by the first incident polarizing element 211 is recycled as image light IB. However, in the projector 100 of this embodiment, the red light LR reflected by the second incident polarizing element 221 is returned to the second incident polarizing element 221 with its polarization direction changed, so that a portion of the re-incident red light LR passes through the second incident polarizing element 221 and is recycled as image light IR generated by the second optical modulation element 220.

[0086] Figure 6 shows the positional relationship between the second light guide element 171 and the second incident polarizing element 221. Figure 6 is a plan view of the second exit end 171b of the second light guide element 171 toward the +D1 side, with the second incident polarizing element 221 superimposed on it. For clarity, the second parallelizing element 172 is omitted from the illustration.

[0087] As shown in Figure 6, the second incident polarizing element 221 has a second polarization transmission axis TX1 that transmits the third polarization component LRp of the red light LR, and a second polarization reflection axis RX1 that reflects the fourth polarization component LRs of the red light LR. The second polarization transmission axis TX1 and the second polarization reflection axis RX1 are orthogonal to each other. The second incident polarizing element 221 is designed to have a reflectance of 80% or more for the fourth polarization component LRs of the red light LR.

[0088] The cross-sectional shape of the second exit end 171b in the plane including the D2 and D3 directions perpendicular to the second optical axis 170 is rectangular. The second exit end 171b has a pair of opposing second long sides 71a and a pair of opposing second short sides 71b that are perpendicular to the pair of second long sides 71a. The pair of second long sides 71a are sides along the D2 direction and are spaced apart in the D3 direction. The pair of second short sides 71b are sides along the D3 direction and are spaced apart in the D2 direction.

[0089] As shown in Figure 6, when viewed in plan along the second optical axis 170, the second polarization reflection axis RX1 is tilted with respect to the second long side portion 71a and the second short side portion 71b, respectively. It can also be said that the second polarization transmission axis TX1 is tilted with respect to the second long side portion 71a and the second short side portion 71b, respectively. The angle between the second polarization reflection axis RX1 and the D3 direction along the second long side portion 71a is set to 15° to 75°, and in the case of the projector 100 of this embodiment, it is set to 45°.

[0090] In the projector 100 of this embodiment, the red reflected light (second reflected light) of the red light LR reflected by the second incident polarizing element 221 is converted into a polarized component that passes through the second incident polarizing element 221 during the process of guiding it through the inside of the second light guide element 171.

[0091] In the projector 100 of this embodiment, the green light LG reflected by the third incident polarizing element 231 is incident on the green light-emitting element 13b of the green light source 13. As described above, the green light-emitting element 13b has a phosphor, so the reflected green light LG is scattered by the phosphor and reflected again, and then incident on the third incident polarizing element 231. The green light LG reflected by the green light-emitting element 13b has a disordered polarization direction and therefore contains a fifth polarization component LGp that passes through the third incident polarizing element 231. For this reason, the green light LG reflected by the third incident polarizing element 231 can be recycled as image light IG generated by the third light modulation element 230 without employing a structure that sets the orientation of the polarization reflection axis in a predetermined direction relative to the exit end face of the light guide element, as is done with the first incident polarizing element 211 and the second incident polarizing element 221.

[0092] As described above, the projector 100 of this embodiment includes a blue light source 11 that emits blue light LB, a first light guide element 161 having a first incident end 161a into which the blue light LB emitted from the blue light source 11 is incident, and a first exit end 161b that emits blue light LB, a first incident polarizing element 211 that transmits a first polarization component LBp of the blue light LB emitted from the first light guide element 161 and reflects a second polarization component LBs that is different from the first polarization component LBp, a first optical modulation element 210 that modulates the first polarization component LBp of the blue light LB emitted from the first incident polarizing element 211 according to image information, and a projection optical system 20 that projects image light IB emitted from the first optical modulation element 210. The first incident polarizing element 211 has a first polarization transmission axis TX that transmits the first polarization component LBp and a first polarization reflection axis RX that reflects the second polarization component LBs. The cross-sectional shape of the first exit end 161b in a plane perpendicular to the first optical axis 160, which passes through the center of the first incident end 161a and the center of the first exit end 161b, is a rectangle having a pair of opposing first long sides 61a and a pair of opposing first short sides 61b that are perpendicular to the pair of first long sides 61a. When viewed in plan along the first optical axis 160, the first polarization reflection axis RX is inclined with respect to the first long sides 61a and the first short sides 61b, respectively. The blue reflected light LB1 reflected by the first incident polarizing element 211 is incident on the first exit end 161b of the first light guide element 161.

[0093] Furthermore, the projector 100 of this embodiment includes a red light source 12 that emits red light LR, a green light source 13 that emits green light LG, a second light guide element 171 having a second incident end 171a into which the red light LR emitted from the red light source 12 is incident, and a second exit end 171b that emits red light LR, a third light guide element 181 having a third incident end 181a into which the green light LG emitted from the green light source 13 is incident, and a third exit end 181b that emits green light LG, and a second incident polarizing element 221 that transmits the third polarization component LRp of the red light LR emitted from the second light guide element 171 and reflects the fourth polarization component LRs. The system further comprises: a third incident polarizing element 231 that transmits the fifth polarization component LGp of the green light LG emitted from the third light guide element 181 and reflects the sixth polarization component LGs; a second optical modulation element 220 that modulates the third polarization component LRp of the red light LR emitted from the second incident polarizing element 221 according to image information; a third optical modulation element 230 that modulates the fifth polarization component LGp of the green light LG emitted from the third incident polarizing element 231 according to image information; and a photosynthesis element 30 that combines the light emitted from the first optical modulation element 210, the light emitted from the second optical modulation element 220, and the light emitted from the third optical modulation element 230. The second incident polarizing element 221 has a second polarization transmission axis TX1 that transmits the third polarization component LRp and a second polarization reflection axis RX1 that reflects the fourth polarization component LRs. The cross-sectional shape of the second exit end 171b in a plane perpendicular to the second optical axis 170, which passes through the center of the second incident end 171a and the center of the second exit end 171b, is a rectangle having a pair of opposing second long sides 71a and a pair of opposing second short sides 71b that are perpendicular to the pair of second long sides 71a. When viewed in plan along the second optical axis 170, the second polarization reflection axis RX1 is inclined with respect to the second long sides 71a and the second short sides 71b, respectively. The red reflected light reflected by the second incident polarizing element 221 is incident on the second exit end 171b of the second light guide element 171.

[0094] According to the projector 100 of this embodiment, at least a portion of the blue reflected light LB1 reflected by the first incident polarizing element 211 can be converted into light containing a first polarization component LBp during the process of guiding it through the inside of the first light guide element 161. In addition, at least a portion of the red light LR reflected by the second incident polarizing element 221 can be converted into light containing a third polarization component LRp during the process of guiding it through the inside of the second light guide element 171. Therefore, according to the projector 100 of this embodiment, the blue reflected light LB1 reflected by the first incident polarizing element 211 is recycled as image light IB generated by the first optical modulation element 210, and the red reflected light reflected by the second incident polarizing element 221 is recycled as image light IR generated by the second optical modulation element 220, thereby increasing the light utilization efficiency of the blue light LB and red light LR emitted from the blue light source 11 and red light source 12. In addition, the green light LG reflected by the third incident polarizing element 231 can also be recycled as image light IG generated by the third optical modulation element 230. Therefore, the projector 100 of this embodiment can increase the light utilization efficiency of each light source 11, 12, and 13. Thus, by increasing the light utilization efficiency of the three colors of light—blue light, red light, and green light—a projector 100 that projects bright color images can be provided.

[0095] The technical scope of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. For example, in the above embodiment, the first light guide element 161, the second light guide element 171, and the third light guide element 181 are all described as being composed of hollow reflectors. However, each of the light guide elements 161, 171, and 181 may be composed as a solid reflector made of a transparent material such as optical glass, and a reflective film made of a dielectric multilayer film or the like may be provided on the outer surface to act as a reflective surface.

[0096] Furthermore, the specific details regarding the shape, number, arrangement, and materials of each component of the projector are not limited to the above embodiment and can be modified as appropriate.

[0097] A summary of this disclosure is provided below.

[0098] (Note 1) A first light source that emits first light in the first wavelength band, A first light guide element having a first input end into which the first light emitted from the first light source is incident, and a first output end that emits the first light, A first reflective polarizing element that transmits a first polarization component of the first light emitted from the first light guide element and reflects a second polarization component having a different polarization direction from the first polarization component, A first optical modulation element modulates the first polarization component of the first light emitted from the first reflective polarizing element according to image information, The system comprises a projection optical system that projects light emitted from the first optical modulation element, The first reflective polarizing element has a first polarization transmission axis that transmits the first polarization component and a first polarization reflection axis that reflects the second polarization component. The cross-sectional shape of the first exit end in a plane perpendicular to the first optical axis passing through the center of the first entrance end and the center of the first exit end is a rectangle having a pair of first long sides facing each other and a pair of first short sides perpendicular to the pair of first long sides and facing each other. When viewed in plan along the first optical axis, the first polarization reflection axis is inclined with respect to the first long side and the first short side, respectively. The first reflected light reflected by the first reflective polarizing element is incident on the first exit end of the first light guide element. A projector characterized by the following features.

[0099] In this projector configuration, at least a portion of the first reflected light reflected by the first reflective polarizing element can be converted into light containing a first polarization component during the process of guiding it through the first light guide element. Therefore, the first reflected light reflected by the first reflective polarizing element can be recycled as image light generated by the first light modulation element. Consequently, the light utilization efficiency of the first light emitted from the first light source can be increased.

[0100] (Note 2) The first reflected light is guided through the interior of the first light guide element and then emitted from the first emission end. The first reflected light emitted from the first ejection end contains the first polarization component and is incident on the first reflective polarizing element. The projector described in Appendix 1, characterized by the features described herein.

[0101] With this configuration, when the first reflected light is incident on the first reflecting polarizing element, the first polarization component contained in the first reflected light can be transmitted through the first reflecting polarizing element. Therefore, at least a portion of the first reflected light can be used to generate image light.

[0102] (Note 3) A second light source that emits second light in a second wavelength band different from the first wavelength band, A third light source that emits third light in a third wavelength band different from the first wavelength band and the second wavelength band, A second light guide element having a second incident end into which the second light emitted from the second light source is incident, and a second exit end that emits the second light, A third light guide element having a third incident end into which the third light emitted from the third light source is incident, and a third exit end that emits the third light, A second reflective polarizing element that transmits the third polarization component of the second light emitted from the second light guide element and reflects the fourth polarization component having a different polarization direction from the third polarization component, A third reflective polarizing element that transmits the fifth polarization component of the third light emitted from the third light guide element and reflects the sixth polarization component having a different polarization direction from the fifth polarization component, A second optical modulation element modulates the third polarization component of the second light emitted from the second reflective polarizing element according to image information, A third optical modulation element modulates the fifth polarization component of the third light emitted from the third reflective polarizing element according to image information, The present invention further comprises a photosynthesis element that synthesizes light emitted from the first optical modulation element, light emitted from the second optical modulation element, and light emitted from the third optical modulation element, The second reflective polarizing element has a second polarizing transmission axis that transmits the third polarizing component and a second polarizing reflection axis that reflects the fourth polarizing component, The cross-sectional shape of the second exit end in a plane perpendicular to the second optical axis passing through the center of the second incident end and the center of the second exit end is a rectangle having a pair of opposing second long sides and a pair of opposing second short sides perpendicular to the pair of second long sides. When viewed in plan along the second optical axis, the second polarization reflection axis is inclined with respect to the second long side and the second short side, respectively. The second reflected light reflected by the second reflective polarizing element is incident on the second exit end of the second light guide element. A projector as described in Appendix 1 or Appendix 2, characterized by the above.

[0103] With this configuration, at least a portion of the second reflected light reflected by the second reflective polarizing element can be converted into light containing a third polarization component during the process of guiding it through the inside of the second light guide element. Therefore, the second reflected light reflected by the second reflective polarizing element can be recycled as image light generated by the second light modulation element. Consequently, the light utilization efficiency of the second light emitted from the second light source can be increased.

[0104] (Note 4) When viewed in a plan view along the first optical axis, the angle between the first polarization reflection axis and the direction along the first long side is between 15° and 75°. A projector characterized by any one of the appendices 1 to 3.

[0105] With this configuration, when the first reflected light reflected by the first reflecting polarizing element is reflected by the first light guiding element, the polarization direction of the first reflected light can be effectively changed. Therefore, the light utilization efficiency of the first light can be effectively increased.

[0106] (Note 5) The first reflective polarizing element has a reflectance of 80% or more for the second polarization component. A projector characterized by any one of the appendices 1 to 4.

[0107] With this configuration, the second polarization component is efficiently reflected by the first reflective polarizing element, allowing the second polarization component to be efficiently reused as image light.

[0108] (Note 6) The first light guide element has a reflective surface that reflects the first light, The reflectance of the reflective surface with respect to the first polarization component is 80% or more. The reflectivity of the reflective surface with respect to the second polarization component is 80% or more. The projector described in Appendix 1, characterized by the features described herein.

[0109] With this configuration, the reflective surface efficiently reflects the first light regardless of the polarization direction, thereby enhancing the effect of improving the light utilization efficiency of the first light.

[0110] (Note 7) The third light source has a phosphor, The first light source and the second light source do not have the phosphor. The projector described in Appendix 3, characterized by the features described herein.

[0111] In this configuration, the third light reflected by the third reflective polarizing element is scattered by the phosphor of the third light source and reflected again, then incident on the third incident polarizing element. At this time, the third light reflected by the phosphor of the third light source has a disordered polarization direction and contains a fifth polarization component that passes through the third incident polarizing element. Therefore, the third light reflected by the third incident polarizing element can be recycled as image light generated by the third light modulation element without employing a structure that sets the orientation of the polarization reflection axis in a predetermined direction relative to the exit end face of the light guide element, as is done with the first and second incident polarizing elements. Thus, the light utilization efficiency of the third light emitted from the third light source can be increased.

[0112] (Note 8) The aforementioned first light is blue light, The aforementioned second light is red light, The third light is green light. The projector described in Appendix 7, characterized by the features described herein.

[0113] This configuration allows for the creation of a projector that projects bright color images by increasing the efficiency of utilizing three colors of light: blue, red, and green. [Explanation of Symbols]

[0114] 11...Blue light source (first light source), 12...Red light source (second light source), 13...Green light source (third light source), 20...Projection optical system, 30...Photosynthesis element, 61a...First long side, 61b...First short side, 71a...Second long side, 71b...Second short side, 100...Projector, 160...First optical axis, 161...First light guide element, 161a...First incident end, 161b...First exit end, 170...Second optical axis, 171...Second light guide element, 171a...Second incident end, 171b...Second exit end, 181...Third light guide element, 181a...Third incident end, 181b...Third exit end, 210...First light modulation element, 211...First incident side deflection Optical element (first reflection polarizer), 220... Second optical modulation element, 221... Second incident polarizer (second reflection polarizer), 230... Third optical modulation element, 231... Third incident polarizer (third reflection polarizer), LB... Blue light (first light), LB1... Blue reflected light (first reflected light), LBp... First polarization component, LBs... Second polarization component, LG... Green light (third light), LGp... Fifth polarization component, LGs... Sixth polarization component, LR... Red light (second light), LRp... Third polarization component, LRs... Fourth polarization component, RX... First polarization reflection axis, RX1... Second polarization reflection axis, TX... First polarization transmission axis, TX1... Second polarization transmission axis.

Claims

1. A first light source that emits first light in the first wavelength band, A first light guide element having a first incident end into which the first light emitted from the first light source is incident, and a first exit end that emits the first light, A first reflective polarizing element that transmits a first polarization component of the first light emitted from the first light guide element and reflects a second polarization component having a different polarization direction from the first polarization component, A first optical modulation element modulates the first polarization component of the first light emitted from the first reflective polarizing element according to image information, The system comprises a projection optical system that projects light emitted from the first optical modulation element, The first reflective polarizing element has a first polarizing transmission axis that transmits the first polarizing component and a first polarizing reflection axis that reflects the second polarizing component. The cross-sectional shape of the first exit end in a plane perpendicular to the first optical axis passing through the center of the first incident end and the center of the first exit end is a rectangle having a pair of first long sides facing each other and a pair of first short sides perpendicular to the pair of first long sides and facing each other. When viewed in plan along the first optical axis, the first polarization reflection axis is inclined with respect to the first long side and the first short side, respectively. The first reflected light reflected by the first reflective polarizing element is incident on the first exit end of the first light guide element. A projector characterized by the following features.

2. The first reflected light is guided through the interior of the first light guide element and then emitted from the first emission end. The first reflected light emitted from the first ejection end contains a first polarization component and is incident on the first reflective polarizing element. The projector according to claim 1.

3. A second light source that emits second light in a second wavelength band different from the first wavelength band, A third light source that emits a third light in a third wavelength band different from the first wavelength band and the second wavelength band, A second light guide element having a second incident end into which the second light emitted from the second light source is incident, and a second exit end that emits the second light, A third light guide element having a third incident end into which the third light emitted from the third light source is incident, and a third exit end that emits the third light, A second reflective polarizing element that transmits the third polarization component of the second light emitted from the second light guide element and reflects the fourth polarization component having a different polarization direction from the third polarization component, A third reflective polarizing element that transmits the fifth polarization component of the third light emitted from the third light guide element and reflects the sixth polarization component having a different polarization direction from the fifth polarization component, A second optical modulation element modulates the third polarization component of the second light emitted from the second reflective polarizing element according to image information, A third optical modulation element modulates the fifth polarization component of the third light emitted from the third reflective polarizing element according to image information, The present invention further comprises a photosynthesis element that synthesizes light emitted from the first optical modulation element, light emitted from the second optical modulation element, and light emitted from the third optical modulation element, The second reflective polarizing element has a second polarizing transmission axis that transmits the third polarizing component and a second polarizing reflection axis that reflects the fourth polarizing component, The cross-sectional shape of the second exit end in a plane perpendicular to the second optical axis passing through the center of the second incident end and the center of the second exit end is a rectangle having a pair of opposing second long sides and a pair of opposing second short sides perpendicular to the pair of second long sides. When viewed in plan along the second optical axis, the second polarization reflection axis is inclined with respect to the second long side and the second short side, respectively. The second reflected light reflected by the second reflective polarizing element is incident on the second exit end of the second light guide element. The projector according to claim 1.

4. When viewed in a plan view along the first optical axis, the angle between the first polarization reflection axis and the direction along the first long side is between 15° and 75°. The projector according to claim 1.

5. The first reflective polarizing element has a reflectance of 80% or more for the second polarization component. The projector according to claim 1.

6. The first light guide element has a reflective surface that reflects the first light, The reflectance of the reflective surface with respect to the first polarization component is 80% or more. The reflectivity of the reflective surface with respect to the second polarization component is 80% or more. The projector according to claim 1.

7. The third light source has a phosphor, The first light source and the second light source do not have the phosphor. The projector according to claim 3.

8. The first light is blue light, The aforementioned second light is red light, The third light is green light. The projector according to feature 7.

Images