Optical modules and projectors

Abstract

To suppress the decrease in light utilization efficiency in optical modules. [Solution] The optical module of the embodiment includes a first light source that emits first light in a first wavelength band, a first light guide element that has 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, and which makes the in-plane illuminance of the first light uniform, a first parallelizing element that parallelizes the first light emitted from the first light guide element, and a first light modulation device that modulates the first light emitted from the first parallelizing element based on image information. The first light modulation device includes a first polarization conversion unit that changes the polarization state of the first light emitted from the first parallelizing element, and a first polarization separation unit that transmits at least a portion of the first polarization component of the first light passing through the first polarization conversion unit and reflects the other portion. The first polarization conversion unit changes the polarization state of the other portion of the first light reflected from the first polarization separation unit.

Description

Technical Field

[0001] The present invention relates to an optical module and a projector.

Background Art

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

[0003] For example, Patent Document 1 discloses a projector including a plurality of light emitting diodes (LEDs) as light emitting elements of a light source. In the projector disclosed in Patent Document 1, the colored light emitted from each LED passes through a block and then overlaps on the same path in the same direction, is modulated into image light by a light modulation element, and is projected by a projection lens. The brightness of the colored light emitted from the emission end of each block is uniformized in a plane intersecting the optical axis. The colored light emitted from a plurality of blocks enters a cross dichroic prism for synthesizing light from a plurality of LEDs with each other.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the projector disclosed in Patent Document 1, when a light source is used that emits colored light containing all polarization components, rather than colored light containing only a specific polarization component like an LED, only the colored light of the specific polarization component is used to form the image, and the colored light of other polarization components is unnecessary, resulting in a decrease in light utilization efficiency. Therefore, there has been a need for measures to improve light utilization efficiency by utilizing the colored light of other polarization components emitted from the light source in addition to the specific polarization component. [Means for solving the problem]

[0006] An optical module according to one aspect of the present invention comprises: a first light source that emits first light in a first wavelength band; a first light guide element having a first incident end into which the first light emitted from the first light source is incident and a first exit end that emits the first light, and which homogenizes the in-plane illuminance of the first light; a first parallelizing element that parallelizes the first light emitted from the first light guide element; and a first light modulation device that modulates the first light emitted from the first parallelizing element based on image information. The first light modulation device comprises a first polarization conversion unit that changes the polarization state of the first light emitted from the first parallelizing element; and a first polarization separation unit that transmits at least a portion of the first polarization component of the first light passing through the first polarization conversion unit and reflects the other portion. The first polarization conversion unit changes the polarization state of the other portion of the first light reflected from the first polarization separation unit. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram showing the configuration of a projector in one embodiment. [Figure 2] Figure 1 is a schematic diagram of the red light emission section of the projector and the optical modulation device that modulates the red light. [Figure 3] Figure 2 is a schematic diagram of the phase difference plate of the incident polarizing element of the optical modulator in the red light emission section. [Figure 4] Figure 2 is a schematic diagram showing the relationship between the crystal axis of the quartz substrate forming the phase difference plate of the incident polarizing element of the optical modulator that modulates red light, and the transmission axis of the reflective polarizing layer. [Figure 5]Figure 2 is a graph showing an example of the wavelength dependence of the phase modulation amount of a single quartz substrate forming the phase difference plate of the incident polarizing element in an optical modulator that modulates red light, and the numerical calculation results of the red light spectrum. [Figure 6] Figure 2 is a graph showing an example of the wavelength dependence of the phase modulation amount of the two bonded quartz substrates used as the incident polarizing element in an optical modulator that modulates red light, and the numerical calculation results of the red light spectrum. [Figure 7] Figure 1 is a schematic diagram of the green light emission section of the projector and the optical modulation device that modulates the green light. [Figure 8] Figure 1 is a schematic diagram of the blue light emission section of the projector and the optical modulation device that modulates the blue light. [Figure 9] Figure 8 is a graph showing an example of the wavelength dependence of the phase modulation amount of a single-plate and two-plate bonded quartz substrates forming the phase difference plate of the incident polarizing element of a light modulator that modulates blue light, and the numerical calculation results of the blue light spectrum. [Figure 10] Figure 2 is a schematic graph showing the ratio of S-polarized and P-polarized red light incident on the reflected polarization layer of the incident polarizing element of the optical modulator that modulates red light. [Figure 11] This is a schematic graph showing the ratio of S-polarized and P-polarized red light incident on the reflective polarization layer of the incident polarizing element in an optical modulator that modulates red light in a conventional projector. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to the drawings. In each drawing, the scale of the dimensions of the components may have been changed to make them easier to see.

[0009] First, one embodiment of the present invention will be described with reference to Figures 1 to 10. Figure 1 is a schematic diagram showing the configuration of a projector 350 according to one embodiment of the present invention. The projector 350 is an image display device equipped with three liquid crystal panels as an optical modulation device, and is a so-called three-panel projector.

[0010] As shown in FIG. 1, the projector 350 includes an optical module 310 and a projection optical system 390. The optical module 310 includes a red light emitting unit 101, a green light emitting unit 102, a blue light emitting unit 103, light modulation devices 481, 482, 483, and a light combining element 200.

[0011] The red light emitting unit 101 emits red light LR. In the following description, the axis parallel to the optical axis of the red light LR emitted from the red light emitting unit 101 is defined as the D1 direction. One side in the D1 direction is the -D1 side, and the side opposite to the -D1 side in the D1 direction is the +D1 side. The direction orthogonal to the D1 direction within the plane including the optical axis of the red light LR is defined as the D2 direction. One side in the D2 direction is the -D2 side, and the side opposite to the -D2 side in the D2 direction is the +D2 side. The direction orthogonal to both the D1 direction and the D2 direction is defined as the D3 direction. The red light LR emitted from the red light emitting unit 101 travels along the D1 direction toward the +D1 side.

[0012] The red light emitting unit 101 includes a light source 121, a light guide element 141, and a collimating element 161. The light source 121 includes a substrate 111 and a light emitting element 421. The light emitting element 421 is provided on the +D1 side plate surface among the plate surfaces parallel to the plane including the D2 direction and the D3 direction on the substrate 111. The light emitting surface of the light emitting element 421 is arranged substantially parallel to the plane including the D2 direction and the D3 direction, and is the surface on the opposite side of the D1 direction from the surface that contacts the +D1 side plate surface of the substrate 111 in the light emitting element 421.

[0013] The light source 121 corresponds to the first light source and emits red light LR in the red wavelength band in the visible wavelength band. The red wavelength band corresponds to the first wavelength band. The red light LR corresponds to the first light. The red light LR diverges from the light emitting surface of the light source 121 according to a predetermined emission angle around the axis parallel to the D1 direction passing through the center of the light emitting surface of the light source 121, and is emitted toward the +D1 side. The red wavelength band is, for example, a wavelength band of 590 nm to 700 nm and includes, for example, 630 nm.

[0014] The light-emitting element 421 corresponds to the first light-emitting element and is composed of, for example, an LED that emits red light LR. The LED that emits red light LR contains, as a light-emitting body, for example, aluminum gallium indium phosphide (AlGaInP) having excellent light extraction efficiency. Note that the light-emitting element 421 may be composed of one LED or may be composed of a plurality of LEDs in total. When the light-emitting element 421 is composed of a plurality of LEDs, the plurality of LEDs are arranged in the region occupied by the light-emitting element 421 within the plane including the D2 direction and the D3 direction.

[0015] By using an LED for the light source 121, the cost of the light source 121 is suppressed, and the speckle noise of the red light included in the image light IM projected onto the screen SCR is reduced.

[0016] The substrate 111 is made of, for example, metal and also acts as a heat dissipation member that receives heat from the light-emitting element 421 that emits red light LR and releases the heat to the external space.

[0017] The light guide element 141 is provided on the optical path of the red light LR emitted from the light source 121 and is arranged on the +D1 side of the light source 121 and at a position overlapping the light source 121 in the D2 direction and the D3 direction. The light guide element 141 corresponds to the first light guide element and has 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 reflection surface 141r extending between the incident end 141a and the emission end 141b in the D1 direction.

[0018] The incident end 141a corresponds to the first incident end and extends parallel to the plane including the D2 direction and the D3 direction. The shape of the incident end 141a when viewed from the D1 direction is the same as the shape of the light-emitting surface of the light source 121 when viewed from the same direction, and is, for example, rectangular, specifically, rectangular. The sizes of the light-emitting surface of the light source 121 in the D2 direction and the D3 direction are, for example, 0.25 mm or more and 10 mm or less. The area of the light-emitting surface of the light source 121 when viewed along the D1 direction is, for example, 0.25 mm 2 ~10 mm × 10 mm 2 is.

[0019] The size of the incident end 141a in the plane including the D2 and D3 directions may be equivalent to the size of the light-emitting surface of the light source 121 in the plane including the D2 and D3 directions, but preferably it is moderately larger than the size of the light-emitting surface of the light source 121 in the plane including the D2 and D3 directions. The dimension along the long side parallel to the D2 direction of the aperture into which the red light LR enters at the incident end 141a is 1 mm or more and 3 mm or less, for example, about 2 mm.

[0020] The exit end 141b corresponds to the first exit end, extends parallel to the plane including the D2 and D3 directions, and is larger than the incident end 141a. The shape of the exit end 141b when viewed from the D1 direction is the same as the modulation plane of the optical modulation element 181 when viewed from the same direction, for example, it is rectangular. The size of the exit end 141b in the plane including the D2 and D3 directions is equivalent to the size of the modulation plane of the optical modulation element 181 in the plane including the D2 and D3 directions.

[0021] The dimension along the long side parallel to the D2 direction of the aperture from which red light LR is emitted at the emission end 141b is 14 mm or more and 16 mm or less, for example, about 15 mm. The size of the modulation surface of the optical modulation element 181 in the long side direction, i.e., in the D2 direction, is for example 15 mm. The size of the modulation surface of the optical modulation element 181 may be appropriately selected within a range from, for example, 6.48 mm × 11.52 mm for a 0.52-inch type to 19.44 mm × 34.56 nm for a 1.5-inch type.

[0022] The side surface 141s and the reflective surface 141r connect the peripheral edge of the incident end 141a and the peripheral edge of the ejection end 141b in the D1 direction.

[0023] The red light LR emitted from the light source 121 enters the light guide element 141 from the incident end 141a. In the light guide element 141, the internal space enclosed by the incident end 141a, the exit end 141b, and the reflective surface 141r is the region through which the red light LR propagates. The size of the internal space of the light guide element 141 in the plane including the D2 and D3 directions increases as it progresses from the -D1 side to the +D1 side in the D1 direction.

[0024] The cross-sectional area of ​​the exit end 141b of the light guide element 141, including the D2 and D3 directions, that is, the area occupied by the cross-section of the exit end 141b parallel to the plane perpendicular to the central axis parallel to the D1 direction of the light guide element 141, is larger than the cross-sectional area of ​​the incident end 141a of the light guide element 141, including the same directions, that is, the area occupied by the cross-section of the incident end 141a parallel to the plane perpendicular to the central axis of the light guide element 141. The area occupied by the cross-section perpendicular to the central axis of the light guide element 141 expands as you move from the incident end 141a to the exit end 141b.

[0025] The shape of the internal space of the light guide element 141, including the D2 and D3 directions, changes from the shape of the light-emitting surface of the light source 121 as viewed from the D1 direction to the shape of the modulation surface of the light modulation element 181 as you move from the -D1 side to the +D1 side.

[0026] The side surface 141s of the light guide element 141, and the reflective surface 141r provided on the side surface 141s as described later, form a predetermined angle with respect to a virtual line perpendicular to the incident end 141a and the central axis of the light guide element 141, and move away from the virtual line in a plane including the D2 and D3 directions as moving from the -D1 side to the +D1 side. The red light LR incident on the light guide element 141 propagates through the internal space of the light guide element 141 from the -D1 side to the +D1 side.

[0027] The shape of the modulation surface of the optical modulation element 181, when viewed along the D1 direction, is rectangular, and the shape of the light-emitting surface of the light source 121, when viewed along the D1 direction, is rectangular. The predetermined angle, i.e., taper angle, that the side surface 141s and reflective surface 141r, which include the short side parallel to the D3 direction of the rectangle, make with respect to the aforementioned imaginary line and the central axis of the optical guide element 141 is, for example, in the range of 7° to 22°. The predetermined angle, i.e., taper angle, that the side surface 141s and reflective surface 141r, which include the long side parallel to the D2 direction of the rectangle, make with respect to the aforementioned imaginary line and the central axis of the optical guide element 141 is, for example, in the range of 14° to 36°. The preferred range of the taper angle is appropriately set by numerical simulation based on the configuration of the red light emission section 101 and ray tracing, so that the reflective film 251 of the optical guide element 141 has a desired reflectivity.

[0028] A portion of the red light LR incident on the light guide element 141 forms an angle smaller than a predetermined taper angle with respect to the aforementioned virtual axis and the central axis of the light guide element 141, and does not occur on the reflective surface 141r even once, propagating directly from the incident end 141a to the exit end 141b. The remaining portion of the red light LR incident on the light guide element 141 forms an angle greater than or equal to the predetermined taper angle with respect to the aforementioned virtual axis and the central axis of the light guide element 141, and occurs on the reflective surface 141r one or more times from the incident end 141a, is reflected by the reflective surface 141r, and then reaches the exit end 141b. The path of the red light LR rays in the internal space of the light guide element 141 differs depending on the angle of incidence to the incident end 141a, and extends to multiple paths with different numbers of reflections at the reflective surface 141r.

[0029] The illuminance distribution of the red light LR propagating through the internal space of the light guide element 141 towards the +D1 side is made uniform in a plane that includes the D2 and D3 directions. In other words, the light guide element 141 makes the illuminance distribution of the incident blue light LB uniform in a plane that includes the D2 and D3 directions. The red light LR having a uniform illuminance distribution is emitted from the emission end 141b towards the +D1 side.

[0030] The light guide element 141 is, for example, a reflector and is formed as a hollow member. When viewed along the D1 direction, the light guide element 141 is formed in a rectangular shape, for example, and tapers from the exit end 141b towards 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, and the +D1 side end of the reflector frame has the same shape and size as the exit end 141b and the modulation surface of the light modulation element 181, and is formed in a rectangular shape of a different size from the -D1 side end.

[0031] The light guide element 141 is composed of, for example, a plate-shaped member and a reflective film 251. If the shape when viewed from the D1 direction of the incident end 141a and the exit end 141b is rectangular, the reflector is composed of, for example, four trapezoidal plate-shaped members and a reflective film 251. The light guide element 141 is composed of, for example, four trapezoidal plate-shaped members with sides corresponding to their legs connected to each other.

[0032] The width, or dimension, 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 of the light guide element 141, is set according to the size of the incident end 141a and the light-emitting surface of the light source 121 in the D2 or D3 direction. The width, or dimension, 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 of the light guide element 141, is set according to the size of the emission end 141b and the modulation surface of the light modulation element 181 in the D2 or D3 direction.

[0033] Considering the size of the light source 121, the width of the edges parallel to the D2 direction on the -D1 side of two of the four plate-shaped members is between 1 mm and 3 mm, for example, about 2 mm. Similarly, the width of the edges parallel to the D2 direction on the +D1 side of the same two plate-shaped members is between 14 mm and 16 mm, for example, about 15 mm. The length in the D1 direction of the four plate-shaped members from the incident end 141a to the injection end 141b is between 5 mm and 25 mm.

[0034] The material of the four plate-shaped members of the light guide element 141 includes at least one of the following: the metals aluminum (Al), silver (Ag), and the transparent material glass, i.e., silicon dioxide (SiO2).

[0035] In the light guide element 141, a reflective film 251 made of a dielectric multilayer film or the like is provided on the plate surface of each of the four plate-shaped members constituting the reflector that faces the internal space, in order to increase the reflectivity of the red light LR incident on the light guide element 141 from the incident end 141a near the side surface 141s. A portion of the red light LR incident on the internal space of the light guide element 141 from the incident end 141a is reflected by the reflective film 251 and propagates toward the +D1 side.

[0036] The intensity of the red light LR reflected by the reflective film 251 and emitted from the reflective film 251 may depend on the angle of incidence of the red light LR incident on the reflective film 251. When the reflective film 251 is composed of a dielectric multilayer film, the dependence of the intensity of the red light LR emitted from the reflective film 251 on the angle of incidence changes depending on parameters such as the number of low-refractive-index layers and high-refractive-index layers constituting the dielectric multilayer film, the refractive index of the low-refractive-index layer, the refractive index of the high-refractive-index layer, and the refractive index difference between the low-refractive-index layer and the high-refractive-index layer. When the reflective film 251 is composed of a metal film, the dependence of the intensity of the red light LR emitted from the reflective film 251 on the angle of incidence changes depending on parameters such as the density of metal particles.

[0037] For example, the spectral reflectance of the reflective film 251 is maximized at a wavelength of approximately 555 nm, which is the wavelength at which human visual sensitivity is highest. This enhances the visibility of the image projected by the projector 350. By adjusting the parameters of the dielectric multilayer film and metal film that constitute the reflective film 251, the wavelength at which the reflectance of the reflective film 251 is maximized can be effectively controlled.

[0038] As described above, for example, when the taper angle of the light guide element 141 is within the range of 7° to 22° or 14° to 36°, the reflective film 251 is designed such that the incident angle of red light LR at which the intensity of red light LR emitted from the reflective surface 141r is highest is within a predetermined angle range, and parameters such as the total number of low-refractive-index layers and high-refractive-index layers constituting the dielectric multilayer film, and the refractive index difference between the low-refractive-index layers and the high-refractive-index layers are appropriately determined. The predetermined angle range is, for example, 60° to 90°. The relationship between the incident angle of red light LR on the reflective surface 141r and the reflective film 251 and the intensity of red light LR emitted from the reflective surface 141r and the reflective film 251 is obtained by numerical simulation based on the configuration of the red light emission unit 101 and ray tracing.

[0039] The parallelizing element 161 is provided on the optical path of the red light LR emitted from the light guide element 141, positioned +D1 side of 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 red light LR emitted from the light guide element 141 along the D1 direction. The parallelizing element 161 corresponds to the first parallelizing element.

[0040] The parallelizing element 161 is, for example, a plano-convex lens, and has an incident surface consisting of a flat surface perpendicular to the D1 direction and an exit surface consisting of a convex curved surface projecting toward the exit side of the red light LR. The focal point of the plano-convex lens constituting the parallelizing element 161 is at least on the -D1 side of the parallelizing element 161, and on the opposite side from 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.

[0041] 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 having the parallelizing element 161 in contact with the exit end 141b, the red light LR emitted from the exit end 141b of the light guide element 141 is captured to the maximum extent by the parallelizing element 161, and the loss of red light LR is suppressed. However, the parallelizing element 161 may be an optical lens other than a plano-convex lens capable of parallelizing the incident red light LR, and may be arranged at an appropriate distance from the light guide element 141 in the D1 direction.

[0042] The optical modulator 481 includes an incident polarizing element 171, an optical modulator 181, and an exit polarizing element 175. The optical modulator 481 corresponds to the first optical modulator and modulates the incident red light LR based on image information transmitted from an externally located image forming apparatus such as a computer (not shown).

[0043] The incident polarizing element 171 is positioned on the optical path of the red light LR emitted from the parallelizing element 161, on the +D1 side of the parallelizing element 161, and overlapping with the parallelizing element 161 in the D2 and D3 directions. The incident polarizing element 171 is positioned, for example, at an appropriate distance from the optical modulation element 181 in the D1 direction, but may also be in contact with the optical modulation element 181 from the -D1 side. The incident polarizing element 171 emits a predetermined polarization of the red light LR emitted from the parallelizing element 161 along the D1 direction towards the +D1 side. The predetermined polarization is, for example, S polarization.

[0044] The incident polarizing element 171 includes, for example, a reflective polarizing layer having a plate surface parallel to the planes including the D2 and D3 directions. The incident polarizing element 171 transmits a portion of the incident red light LR, including a predetermined polarization, to the +D1 side, and reflects the other portion of the red light LR to the -D1 side.

[0045] The red light LR emitted from the light source 121 includes at least P-polarized and S-polarized light, and is, for example, randomly polarized. The P-polarized component of the red light LR emitted from the light source 121 passes sequentially through the light guide element 141 and the parallelizing element 161 as described above, passes through the incident polarizing element 171, and is emitted on the +D1 side of the incident polarizing element 171. The S-polarized component of the red light LR passes sequentially through the light guide element 141 and the parallelizing element 161, similar to the P-polarized component, but is reflected at the incident plane of the incident polarizing element 171 and is emitted on the -D1 side of the incident polarizing element 171.

[0046] The optical modulation element 181 is positioned on the optical path of the red light LR emitted from the incident polarizing element 171, on the +D1 side of the incident polarizing element 171, and overlapping with the incident polarizing element 171 in the D2 and D3 directions. The optical modulation element 181 modulates the red light LR emitted from the incident polarizing element 171 based on image information transmitted from an externally connected image forming apparatus (not shown) to the optical modulation element 181.

[0047] The optical modulation element 181 is, for example, a transmissive liquid crystal panel. The liquid crystal panel constituting the optical modulation element 181 has a plurality of pixels (not shown). Each pixel is equipped with a switching element. The switching element is, for example, a polysilicon thin-film transistor (TFT). The switching element of each pixel is supplied with an electrical signal corresponding to the brightness of red light at the relative position of each pixel on the modulation plane of the optical modulation element 181 in the image projected by the projector 350. Each pixel modulates the vibration direction of the red light LR incident from the incident polarizing element 171 by the operation of the switching element in accordance with the aforementioned electrical signal, and generates red image light IR. Image light IR corresponds to the second light. The optical modulation element 181 emits the image light IR generated by the liquid crystal panel along the D1 direction towards the +D1 side.

[0048] The exit-side polarizing element 175 is provided on the optical path of the image light IR emitted from the optical modulation element 181, positioned +D1 side of the optical modulation element 181, and overlapping with the optical modulation element 181 in the D2 and D3 directions. The exit-side polarizing element 175 is, for example, in contact with the incident surface of the image light IR in the photosynthesis element 200, i.e., the incident surface 210c of the cross dichroic prism 210 described later, from the -D1 side, but may be positioned with an appropriate distance from the optical modulation element 181 and the photosynthesis element 200 in the D1 direction. The exit-side polarizing element 175 converts the image light IR emitted from the optical modulation element 181 into circularly polarized image light IR and emits the circularly polarized image light IR along the D1 direction towards the +D1 side.

[0049] The exit-side polarizing element 175 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 exit-side polarizing element 175 transmits a portion of the incident image light IR, including a predetermined polarization, to the +D1 side, and reflects or absorbs the other portion of the image light IR to the -D1 side. If it is desired to suppress the generation of reflected light and stray light to the optical modulation element 181, it is desirable to use an absorbing polarizer as the exit-side polarizing element 175.

[0050] The detailed configurations of the incident polarizing element 171, the optical modulation element 181, and the exit polarizing element 175 of the optical modulation device 481 will be described later.

[0051] The green light emitter 102 is positioned on the +D1 and -D2 sides of the red light emitter 101, and is located in a region that overlaps with the red light emitter 101 in the D3 direction. The green light emitter 102 emits green light LG. The green light LG emitted from the green light emitter 102 travels along the D2 direction towards the +D2 side.

[0052] The green light emitting section 102 includes a light source 122, a light guide element 142, and a parallelizing element 162. The light source 122 includes a substrate 112 and a light-emitting element 422. The light-emitting element 422 is provided on the +D2 side surface of the substrate 112, which is parallel to the plane including the D1 and D3 directions. The light-emitting surface of the light-emitting element 422 is arranged substantially parallel to the plane including the D1 and D3 directions, and is the surface opposite in the D2 direction to the surface of the light-emitting element 422 that is in contact with the +D2 side surface of the substrate 112.

[0053] Light source 122 corresponds to the third light source and emits green light LG in the green wavelength band of the visible wavelength band. The green wavelength band corresponds to the third wavelength band. Green light LG corresponds to the third light. The green wavelength band is different from the red wavelength band, for example, the wavelength band of 500 nm to 590 nm, and for example, includes 532 nm.

[0054] The light-emitting element 422 has, for example, an LED that emits green light LG. In the green light emission unit 102, in order to optimize the green wavelength band and intensity of the green light LG relative to the red wavelength band and intensity of the red light LR emitted in the red light emission unit 101 and the blue wavelength band and intensity of the blue light LB emitted in the blue light emission unit 103, the light-emitting element 422 is composed of, for example, an LED with a built-in phosphor.

[0055] The light-emitting element 422 is provided on the +D2 side of the substrate 112. The light-emitting element 422 may be, for example, an LED that emits blue light having the same blue wavelength band as the light source 121. By having the light-emitting element 422 have an LED body, the cost of the light source 122 is reduced, and the speckle noise of the green light included in the image light IM is reduced.

[0056] The light-emitting element 422 may be composed of a single LED, or it may be composed of multiple LEDs, similar to the light-emitting element 421. If the light-emitting element 422 is composed of multiple LEDs, the multiple LEDs are arranged in the region occupied by the light source 122 in a plane including the D1 and D3 directions.

[0057] The substrate 112 is made of, for example, metal and also acts as a heat dissipation member that receives heat from the light-emitting element 422 that emits green light LG and releases that heat into the external space.

[0058] The light guide element 142 is provided on the optical path of the green light LG emitted from the light source 122, positioned on the +D2 side of the light source 122, and overlapping with the light source 122 in the D1 and D3 directions. The light guide element 142 corresponds to the third light guide element and has an incident end 142a on the -D2 side in the D2 direction, an exit end 142b on the +D2 side, and a side surface 142s and a reflective surface 142r extending between the incident end 142a and the exit end 142b in the D2 direction.

[0059] The incident end 142a corresponds to the third incident end and extends parallel to the plane including the D1 and D3 directions. The shape of the incident end 142a when viewed from the D2 direction is the same as the shape of the light-emitting surface of the light source 122 when viewed from the same direction, for example, it is rectangular, specifically rectangular. The size of the light-emitting surface of the light source 122 in the D1 and D3 directions is, for example, 0.25 mm or more and 10 mm or less. The area of ​​the light-emitting surface of the light source 121 when viewed along the D2 direction is, for example, 0.25 mm. 2 ~10mm x 10mm 2 That is the case.

[0060] The size of the incident end 142a in the plane including the D1 and D3 directions may be equivalent to the size of the light-emitting surface of the light source 122 in the plane including the D1 and D3 directions, but preferably it is moderately larger than the size of the light-emitting surface of the light source 122 in the plane including the D1 and D3 directions. The dimension along the long side parallel to the D1 direction of the aperture into which the green light LG enters at the incident end 142a is 1 mm or more and 3 mm or less, preferably about 2 mm.

[0061] The exit end 142b corresponds to the third exit end, extends parallel to the plane including the D1 and D3 directions, and is larger than the incident end 142a. The shape of the exit end 142b when viewed from the D2 direction is the same as the modulation plane of the optical modulation element 182 when viewed from the same direction, for example, it is rectangular. The size of the exit end 142b in the plane including the D1 and D3 directions is equivalent to the size of the modulation plane of the optical modulation element 182 in the plane including the D1 and D3 directions.

[0062] The dimension along the longer side parallel to the D1 direction of the aperture from which the green light LG is emitted at the emission end 142b is 14 mm or more and 16 mm or less, for example, about 15 mm. The size of the modulation surface of the optical modulation element 182 may be appropriately selected within a range from, for example, 6.48 mm × 11.52 mm for a 0.52-inch type to 19.44 mm × 34.56 nm for a 1.5-inch type.

[0063] The side surface 142s and the reflective surface 142r connect the peripheral edge of the incident end 142a and the peripheral edge of the ejection end 142b in the D2 direction.

[0064] The green light LG emitted from the light source 122 enters the light guide element 142 from the incident end 142a. In the light guide element 142, the internal space enclosed by the incident end 142a, the exit end 142b, and the reflective surface 142r is the region through which the green light LG propagates. The size of the internal space of the light guide element 142 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.

[0065] The cross-sectional area of ​​the exit end 142b of the light guide element 142, including the D1 and D3 directions, that is, the area occupied by the cross-section of the exit end 142b parallel to the plane perpendicular to the central axis parallel to the D2 direction of the light guide element 142, is larger than the cross-sectional area of ​​the incident end 142a of the light guide element 142, including the same directions, that is, the area occupied by the cross-section of the incident end 142a parallel to the plane perpendicular to the central axis of the light guide element 142. The area occupied by the cross-section perpendicular to the central axis of the light guide element 142 expands as you move from the incident end 142a to the exit end 142b.

[0066] The shape of the internal space of the light guide element 142, including the D1 and D3 directions, changes from the shape of the light-emitting surface of the light source 122 as viewed from the D2 direction to the shape of the modulation surface of the light modulation element 182 as you move from the -D2 side to the +D2 side.

[0067] 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 a virtual line perpendicular to the incident end 142a and the central axis of the light guide element 142, and move away from the virtual line in a plane including the D1 and D3 directions as it moves from the -D2 side to the +D2 side. The green light LG incident on the light guide element 142 propagates through the internal space of the light guide element 142 from the -D2 side to the +D2 side.

[0068] The shape of the modulation surface of the optical modulation element 182, when viewed along the D2 direction, is rectangular, and the shape of the light-emitting surface of the light source 122, when viewed along the D2 direction, is rectangular. The predetermined angle, i.e., taper angle, that the side surface 142s and reflective surface 142r, which include the short side parallel to the D3 direction of the rectangle, make with respect to the virtual line and the central axis of the light guide element 142 is, for example, in the range of 7° to 22°. The predetermined angle, i.e., taper angle, that the side surface 141s and reflective surface 141r, which include the long side parallel to the D2 direction of the rectangle, make with respect to the virtual line and the central axis of the light guide element 142 is, for example, in the range of 14° to 36°. The preferred range of the taper angle is appropriately set by numerical simulation based on the configuration of the green light emission section 102 and ray tracing, so that the reflective film 252 of the light guide element 142 has a desired reflectivity.

[0069] Some of the light rays of the green light LG incident on the light guide element 142 form an angle smaller than a predetermined taper angle with respect to the virtual line and the central axis of the light guide element 142, and do not occur on the reflective surface 142r even once, propagating directly from the incident end 142a to the exit end 142b. The remaining portion of the light rays of the green light LG incident on the light guide element 142 forms an angle greater than or equal to the predetermined taper angle with respect to the virtual line and the central axis of the light guide element 142, occur once on the reflective surface 142r from the incident end 142a, are reflected by the reflective surface 142r, and then reach the exit end 142b. The light rays of the green light LG incident on the light guide element 142, other than the remaining portion of the light rays, occur on the reflective surface 142r two or more times from the incident end 142a, are repeatedly reflected by the reflective surface 142r, and then reach the exit end 142b.

[0070] The path of the green light LG within the internal space of the light guide element 142 differs depending on the angle of incidence to the incident end 142a, and extends to multiple paths with different numbers of reflections at the reflective surface 142r. As a result, the illuminance distribution of the green light LG propagating within the internal space of the light guide element 142 is made uniform in a plane including the D1 and D3 directions. In other words, the light guide element 142 makes the illuminance distribution of the incident green light LG uniform in a plane including the D1 and D3 directions. The green light LG with a uniform illuminance distribution is emitted from the emission end 142b towards the +D2 side.

[0071] The light guide element 142, like the light guide element 141, is a hollow reflector composed of, for example, a plate-shaped member. When viewed along the D2 direction, the light guide element 142 is formed in a rectangular shape, for example, and tapers from the ejection end 142b towards the incident end 142a. 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 of the light source 122, and is formed in a rectangular shape, for example. The +D2 side end of the reflector frame has the same shape and size as the ejection end 142b and the modulation surface of the light modulation element 182, and is formed in a rectangular shape of a different size from the -D2 side end, for example.

[0072] The light guide element 142 is composed of a plate-shaped member and a reflective film 252. The light guide element 142 is constructed, for example, by connecting the edges corresponding to the legs of four trapezoidal plate-shaped members. The width, or dimension, of the edge on the -D2 side, which corresponds to the upper base of the four plate-shaped members and is parallel to the D1 or D3 direction, is set according to the size of the incident end 142a and the light-emitting surface of the light source 122 in the D1 or D3 direction. The width, or dimension, of the edge on the +D2 side, which corresponds to the lower base of the four plate-shaped members of the light guide element 142 and is parallel to the D1 or D3 direction, is set according to the size of the emission end 142b and the modulation surface of the light modulation element 182 in the D1 or D3 direction.

[0073] Considering the size of the light source 122, the width, or dimension, of the edges parallel to the D1 direction on the -D2 side of two of the four plate-shaped members that are opposite each other is between 1 mm and 3 mm, for example, about 2 mm. The width, or dimension, of the edges parallel to the D1 direction on the +D2 side of the two aforementioned plate-shaped members is between 14 mm and 16 mm, for example, about 15 mm. The length in the D2 direction of the four plate-shaped members from the incident end 142a to the exit end 142b is, for example, between 5 mm and 25 mm. The shape of the light guide element 142 is the same as the shape of the light guide element 141.

[0074] The material of the four plate-shaped members of the light guide element 142 includes at least one of Al, Ag, and glass, i.e., SiO2, and is the same as, for example, the material of the plate-shaped members of the light guide element 141.

[0075] In the reflector of the light guide element 142, in order to increase the reflectivity of the green light LG incident on the light guide element 142 from the incident end 142a near the side surface 142s, a reflective film 252 such as a dielectric multilayer film is provided on the plate-shaped member constituting the reflector, on the plate surface opposite to the side surface 142s, that is, the plate surface facing the internal space of the light guide element 142. Some of the light rays of the green light LG, including the light rays incident on the internal space of the light guide element 142 from the incident end 142a, are reflected by the reflective film 252 and propagate toward the +D2 side.

[0076] The intensity of the green light LG reflected by the reflective film 252 and emitted from the reflective film 252 may depend on the angle of incidence of the green light LG incident on the reflective film 252. When the reflective film 252 is composed of a dielectric multilayer film, the dependence of the intensity of the green light LG emitted from the reflective film 252 on the angle of incidence changes depending on parameters such as the number of low-refractive-index layers and high-refractive-index layers constituting the dielectric multilayer film, the refractive index of the low-refractive-index layer, the refractive index of the high-refractive-index layer, and the refractive index difference between the low-refractive-index layer and the high-refractive-index layer. When the reflective film 252 is composed of a metal film, the dependence of the intensity of the green light LG emitted from the reflective film 252 on the angle of incidence changes depending on parameters such as the density of metal particles.

[0077] For example, the spectral reflectance of the reflective film 252 is maximized at the wavelength at which human visual sensitivity is highest, thereby improving the visibility of the image projected by the projector 350. By adjusting the parameters of the dielectric multilayer film and metal film that constitute the reflective film 252, the wavelength at which the reflectance of the reflective film 252 is maximized can be effectively controlled.

[0078] In the light guide element 142, for example, when the taper angle of the light guide element 142 is within the range of 7° to 22° or 14° to 36°, the reflective film 252 is designed such that the incident angle of green light LG at which the intensity of green light LG emitted from the reflective surface 142r and the reflective film 252 is within a predetermined angle range, and the parameters of the dielectric multilayer film are appropriately determined. The predetermined angle range is, for example, 60° to 90°. The relationship between the incident angle of green light LG to the reflective film 252 and the intensity of green light LG emitted from the reflective film 252 is also obtained by numerical simulation based on the configuration of the green light emission unit 102 and ray tracing.

[0079] The parallelizing element 162 is provided on the optical path of the green light LG emitted from the light guide element 142, positioned +D2 side of the light guide element 142, and overlapping 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. The parallelizing element 162 corresponds to the first parallelizing element.

[0080] The parallelizing element 162 is, for example, a plano-convex lens, and has an incident surface consisting of a flat surface perpendicular to the D2 direction and an exit surface consisting of a convex curved surface projecting toward the exit side of the green light LG. The focal point of the plano-convex lens constituting the parallelizing element 162 is at least on the -D2 side of the parallelizing element 162, and on the opposite side from the +D2 side from which the green light LG is emitted from the parallelizing element 162, and further on the -D2 side of the light guide element 142.

[0081] The incident surface of the parallelizing element 162 is in contact with the exit end 142b of the light guide element 142. By having the parallelizing element 162 in contact with the exit end 142b, the green light LG emitted from the exit end 142b of the light guide element 142 is captured to the maximum extent by the parallelizing element 162, and the loss of green light LG is suppressed. However, the parallelizing element 162 may be an optical lens other than a plano-convex lens capable of parallelizing the incident green light LG, and may be arranged at an appropriate distance from the light guide element 142 in the D2 direction.

[0082] The optical modulator 482 includes an incident polarizing element 172, an optical modulator 182, and an exit polarizing element 176. The optical modulator 482 corresponds to a third optical modulator and modulates the incident green light LG based on image information transmitted from an externally located image forming apparatus such as a computer (not shown).

[0083] The incident polarizing element 172 is positioned on the optical path of the green light LG emitted from the parallelizing element 162, on the +D2 side of the parallelizing element 162, and overlapping with the parallelizing element 162 in the D1 and D3 directions. The incident polarizing element 172 is positioned, for example, at an appropriate distance from the optical modulation element 182 in the D2 direction, but may also be in contact with the optical modulation element 182 from the -D2 side. The incident polarizing element 172 emits a predetermined polarization of the green light LG emitted from the parallelizing element 162 along the D2 direction towards the +D2 side. The predetermined polarization is, for example, P polarization.

[0084] The incident polarizing element 172 is, for example, a reflective polarizing plate having a plate surface parallel to the planes including the D1 and D3 directions. The incident polarizing element 172 transmits a portion of the incident green light LG, including a predetermined polarization, to the +D2 side, and reflects the other portion of the green light LG to the -D2 side. When the light source 122 has a phosphor, as in the green light emission unit 102, it is desirable that the incident polarizing element 172 be a reflective polarizing plate, since the light reflected from the reflective polarizing plate can be used to excite the phosphor.

[0085] The green light LG emitted from the light source 122 is randomly polarized, containing at least P-polarized and S-polarized light. The green light LG emitted from the light source 122, containing S-polarized and P-polarized components, passes through the light guide element 142, where the illuminance distribution is made uniform in a plane including the D1 and D3 directions, and is emitted towards the +D2 side of the light guide element 142. The green light LG passes through the parallelization element 162 and is parallelized by the parallelization element 162.

[0086] The parallelized green light LG is incident on the incident polarizing element 172 from the -D2 side. The P-polarized component of the green light LG is transmitted through the incident polarizing element 172 and emitted on the +D2 side of the incident polarizing element 172. The S-polarized component of the green light LG is reflected at the incident plane of the incident polarizing element 172 and emitted on the -D2 side of the incident polarizing element 172.

[0087] The green light LG reflected from the incident polarizing element 172 to the -D2 side passes sequentially through the parallelizing element 162 and the light guide element 142, travels along the D2 direction to the -D2 side, is focused in a plane including the D1 and D3 directions, and is incident on the phosphor of the light source 122 from the +D2 side. The phosphor is re-excited by the S-polarized component of the green light LG emitted from the incident polarizing element 172 to the -D2 side, and green light LG containing both S-polarized and P-polarized components is emitted again to the +D2 side from the emission surface of the phosphor.

[0088] Since the incident polarizing element 172 is composed of a reflective polarizer, the polarization of the green light LG that does not pass through the incident polarizing element 172 is re-incident to the phosphor of the light source 122, contributing to the excitation and emission of light from the phosphor.

[0089] The optical modulation element 182 is positioned on the optical path of the green light LG emitted from the incident polarizing element 172, on the +D2 side of the incident polarizing element 172, and overlapping with the incident polarizing element 172 in the D1 and D3 directions. The optical modulation element 182 modulates the green light LG emitted from the incident polarizing element 172 based on image information transmitted from an externally connected image forming apparatus (not shown) to the optical modulation element 182.

[0090] The optical modulation element 182 is, for example, a transmissive liquid crystal panel. The liquid crystal panel constituting the optical modulation element 182 has a plurality of pixels (not shown). Each pixel is equipped with a switching element. The switching element is, for example, a TFT. The switching element of each pixel is supplied with an electrical signal corresponding to the brightness of green light at the relative position of each pixel on the modulation plane of the optical modulation element 182 in the image projected by the projector 350. Each pixel modulates the vibration direction of the green light LG incident from the incident polarizing element 172 by the operation of the switching element in accordance with the aforementioned electrical signal, and generates green image light IG. Image light IG corresponds to the third light. The optical modulation element 182 emits the image light IG generated by the liquid crystal panel along the D2 direction towards the +D2 side.

[0091] The exit-side polarizing element 176 is provided on the optical path of the image light IG emitted from the optical modulation element 182, positioned +D2 side of the optical modulation element 182, and overlapping with the optical modulation element 182 in the D1 and D3 directions. The exit-side polarizing element 176 is in contact with the incident surface of the image light IG in the photosynthesis element 200, i.e., the incident surface 210d of the cross dichroic prism 210 described later, from the -D2 side, but may be positioned with an appropriate distance from the optical modulation element 182 and the photosynthesis element 200 in the D2 direction. The exit-side polarizing element 176 converts the image light IG emitted from the optical modulation element 182 into circularly polarized image light IG and emits the circularly polarized image light IG along the D2 direction towards the +D2 side. The predetermined polarization is, for example, P polarization.

[0092] The exit-side polarizing element 176 is, for example, a reflective polarizer or an absorbing polarizer having a plate surface parallel to the planes including the D1 and D3 directions. The exit-side polarizing element 176 transmits a portion of the incident image light IG, including a predetermined polarization, to the +D2 side, and reflects or absorbs the other portion of the image light IG to the -D2 side. If it is desirable to suppress the generation of reflected light and stray light to the optical modulation element 182, it is preferable to use an absorbing polarizer as the exit-side polarizing element 176.

[0093] The blue light emitter 103 is positioned on the +D1 side of the green light emitter 102 and is located in a region that overlaps with the red light emitter 101 in the D2 and D3 directions. The blue light emitter 103 emits blue light LB. The blue light LB emitted from the blue light emitter 103 travels along the D1 direction toward the -D1 side.

[0094] The blue light emitting section 103 includes a light source 123, a light guide element 143, and a parallelizing element 163. The light source 123 includes a substrate 113 and a light-emitting element 423. The light-emitting element 423 is provided on the -D1 side of the substrate 113, which is a plate surface parallel to the plane including the D2 and D3 directions. The light-emitting surface of the light-emitting element 423 is arranged substantially parallel to the plane including the D2 and D3 directions, and is the surface opposite in the D2 direction to the surface of the light-emitting element 423 that is in contact with the +D2 side plate surface of the substrate 113.

[0095] Light source 123 corresponds to the second light source and emits blue light LB in the blue wavelength band of the visible wavelength range. The blue wavelength band is different from the red wavelength band and the green wavelength band, and is, for example, the wavelength band from 430 nm to 500 nm, including, for example, 467 nm.

[0096] The light-emitting element 423 corresponds to the second light-emitting element and is composed of, for example, an LED that emits blue light LB. The LED that emits blue light LB contains, for example, a gallium nitride (GaN) semiconductor material that has excellent light extraction efficiency as its light-emitting material. The light-emitting element 423 may consist of a single LED or of multiple LEDs. When the light-emitting element 423 is composed of multiple LEDs, the multiple LEDs are arranged in the region occupied by the light-emitting element 423 in a plane including the D2 and D3 directions.

[0097] By using LEDs as the light source 123, the cost of the light source 123 is reduced, and the speckle noise of blue light contained in the image light IM projected onto the screen SCR is reduced.

[0098] The substrate 113 is made of, for example, metal and also acts as a heat dissipation member that receives heat from the light-emitting element 423 that emits blue light LB and releases that heat into the surrounding space.

[0099] The light guide element 143 is provided on the optical path of the blue light LB emitted from the light source 123, and is positioned -D1 side of the light source 123, and overlaps with the light source 123 in the D2 and D3 directions. The light guide element 143 corresponds to the second light guide element and has an incident end 143a on the +D1 side in the D1 direction, an exit end 143b on the -D1 side, and a side surface 143s and a reflective surface 143r extending between the incident end 143a and the exit end 143b in the D1 direction.

[0100] The incident end 143a corresponds to the second incident end and extends parallel to the plane including the D2 and D3 directions. The shape of the incident end 143a when viewed from the D1 direction is the same as the shape of the light-emitting surface of the light source 123 when viewed from the same direction, for example, it is rectangular, specifically rectangular. The size of the light-emitting surface of the light source 123 in the D2 and D3 directions is, for example, 0.25 mm or more and 10 mm or less. The area of ​​the light-emitting surface of the light source 123 when viewed along the D1 direction is, for example, 0.25 mm². 2 ~10mm x 10mm 2 That is the case.

[0101] The size of the incident end 143a in the plane including the D2 and D3 directions may be equivalent to the size of the light-emitting surface of the light source 123 in the plane including the D2 and D3 directions, but preferably it is moderately larger than the size of the light-emitting surface of the light source 123 in the plane including the D2 and D3 directions. The dimension along the long side parallel to the D2 direction of the aperture into which the blue light LB enters at the incident end 143a is 1 mm or more and 3 mm or less, for example, about 2 mm.

[0102] The exit end 143b corresponds to the second exit end, extends parallel to the plane including the D2 and D3 directions, and is larger than the incident end 143a. The shape of the exit end 143b when viewed from the D1 direction is the same as the modulation plane of the optical modulation element 183 when viewed from the same direction, for example, it is rectangular. The size of the exit end 143b in the plane including the D2 and D3 directions is equivalent to the size of the modulation plane of the optical modulation element 183 in the plane including the D2 and D3 directions.

[0103] The dimension along the long side parallel to the D2 direction of the aperture from which the blue light LB is emitted at the emission end 143b is 14 mm or more and 16 mm or less, for example, about 15 mm. The size of the modulation surface of the optical modulation element 183 in the long side direction, i.e., in the D2 direction, is for example 15 mm. The size of the modulation surface of the optical modulation element 183 may be appropriately selected within a range from, for example, 6.48 mm × 11.52 mm for a 0.52-inch type to 19.44 mm × 34.56 nm for a 1.5-inch type.

[0104] The side surface 143s and the reflective surface 143r connect the peripheral edge of the incident end 143a and the peripheral edge of the ejection end 143b in the D1 direction.

[0105] The blue light LB emitted from the light source 123 enters the light guide element 143 from the incident end 143a. In the light guide element 143, the internal space enclosed by the incident end 143a, the exit end 143b, and the reflective surface 143r is the region through which the blue light LB propagates. The size of the internal space enclosed by the incident end 143a, the exit end 143b, and the reflective surface 143r 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.

[0106] The cross-sectional area of ​​the exit end 143b of the light guide element 143, including the D2 and D3 directions, that is, the area occupied by the cross-section of the exit end 143b parallel to the plane perpendicular to the central axis parallel to the D1 direction of the light guide element 143, is larger than the cross-sectional area of ​​the incident end 143a of the light guide element 143, including the same direction, that is, the area occupied by the cross-section of the incident end 143a parallel to the plane perpendicular to the central axis of the light guide element 143. The area occupied by the cross-section perpendicular to the central axis of the light guide element 143 expands as you move from the incident end 143a to the exit end 143b.

[0107] The shape of the internal space of the light guide element 143, including the D2 and D3 directions, changes from the shape of the light-emitting surface of the light source 123 as viewed from the D1 direction to the shape of the modulation surface of the light modulation element 183 as you move from the +D1 side to the -D1 side.

[0108] The side surface 143s of the light guide element 143, and the reflective surface 143r provided on the side surface 143s as described later, form a predetermined angle with respect to a virtual line perpendicular to the incident end 143a and the central axis of the light guide element 143, and move away from the virtual line in a plane including the D2 and D3 directions as it moves from the +D1 side to the -D1 side. The blue light LB incident on the light guide element 143 propagates from the +D1 side to the -D1 side in the internal space enclosed by the incident end 143a, the exit end 143b, and the reflective surface 143r.

[0109] The shape of the modulation surface of the optical modulation element 183, when viewed along the D1 direction, is rectangular, and the shape of the light-emitting surface of the light source 123, when viewed along the D1 direction, is rectangular. The predetermined angle, i.e., taper angle, that the side surface 143s and reflective surface 143r, which include the short side parallel to the D3 direction of the rectangle, make with respect to the aforementioned imaginary line and the central axis of the light guide element 143 is, for example, in the range of 7° to 22°. The predetermined angle, i.e., taper angle, that the side surface 143s and reflective surface 143r, which include the long side parallel to the D2 direction of the rectangle, make with respect to the aforementioned imaginary line and the central axis of the light guide element 143 is in the range of 14° to 36°. The preferred range of the taper angle is appropriately set, as described later, by numerical simulation based on the configuration of the blue light emission section 103 and ray tracing, so that the reflective film 253 of the light guide element 143 has a desired spectral reflectance.

[0110] A portion of the blue light LB incident on the light guide element 143 forms an angle smaller than a predetermined taper angle with respect to the virtual axis and the central axis of the light guide element 143, and does not occur on the reflective surface 143r even once, propagating directly from the incident end 143a to the exit end 143b. The remaining portion of the blue light LB incident on the light guide element 143 forms an angle greater than or equal to a predetermined taper angle with respect to the virtual axis and the central axis of the light guide element 143, and occurs on the reflective surface 143r one or more times from the incident end 143a, is reflected by the reflective surface 143r, and then reaches the exit end 143b. The path of the blue light LB rays in the internal space of the light guide element 143 differs depending on the angle of incidence to the incident end 143a, and extends to multiple paths with different numbers of reflections at the reflective surface 143r.

[0111] The illuminance distribution of the blue light LB propagating through the internal space of the light guide element 143 is made uniform in a plane that includes the D2 and D3 directions. In other words, the light guide element 143 makes the illuminance distribution of the incident blue light LB uniform in a plane that includes the D2 and D3 directions. The blue light LB with a uniform illuminance distribution is emitted from the emission end 143b toward the -D1 side.

[0112] The light guide element 143, like the light guide elements 141 and 142, is a hollow reflector composed of, for example, a plate-shaped member. When viewed along the D1 direction, the light guide element 143 is formed in a rectangular shape, for example, and tapers from the exit end 141b towards the incident end 141a. When viewed along the D1 direction, the +D1 side end of the light guide element 143 has the same shape and size as the incident end 143a and the light-emitting surface of the light source 123, and is formed in a rectangular shape, for example. The -D1 side end of the light guide element 143 has the same shape and size as the exit end 143b and the modulation surface of the light modulation element 183, and is formed in a rectangular shape of a different size from the +D1 side end, for example.

[0113] The reflector of the light guide element 143 is composed of four plate-shaped members and a reflective film 253. The light guide element 143 is constructed by connecting the edges corresponding to the legs of four trapezoidal plate-shaped members. The width, or dimension, of the edge on the +D1 side, which corresponds to the upper base of the four plate-shaped members and is parallel to the D2 or D3 direction, is set according to the size of the incident end 143a and the light-emitting surface of the light source 123 in the D2 or D3 direction. The width, or dimension, of the edge on the -D1 side, which corresponds to the lower base of the four plate-shaped members and is parallel to the D2 or D3 direction, is set according to the size of the emission end 143b and the modulation surface of the light modulation element 183 in the D2 or D3 direction.

[0114] Considering the size of the light source 123, the width of the edge parallel to the D2 direction on the +D1 side of the plate-shaped member of the light guide element 143 is between 1 mm and 3 mm, for example, about 2 mm. The width of the edge parallel to the D2 direction on the -D1 side of the plate-shaped member of the light guide element 143 is between 14 mm and 16 mm, for example, about 15 mm. The length in the D1 direction of the plate-shaped member of the light guide element 143 from the incident end 143a to the exit end 143b is, for example, between 5 mm and 25 mm. The shape of the light guide element 143 is the same as the shape of the light guide elements 141 and 142.

[0115] The material of the four plate-shaped members of the light guide element 143 includes at least one of Al, Ag, and glass, i.e., SiO2, and is the same as the material of the plate-shaped members of the light guide elements 141 and 142, for example.

[0116] In the reflector of the light guide element 143, in order to increase the reflectivity of the blue light LB incident on the light guide element 143 from the incident end 143a near the side surface 143s, a reflective film 253 made of a dielectric multilayer film or the like is provided on the plate-shaped member constituting the reflector, on the plate surface opposite to the side surface 143s, that is, the plate surface facing the internal space of the light guide element 143. A portion of the blue light LB incident on the internal space of the light guide element 143 from the incident end 143a is reflected by the reflective film 253 and propagates toward the -D1 side.

[0117] The intensity of the blue light LB reflected by the reflective film 253 and emitted from the reflective film 253 may depend on the angle of incidence of the blue light LB incident on the reflective film 253. When the reflective film 253 is composed of a dielectric multilayer film, the dependence of the intensity of the blue light LB emitted from the reflective film 253 on the angle of incidence changes depending on parameters such as the number of low-refractive-index layers and high-refractive-index layers constituting the dielectric multilayer film, the refractive index of the low-refractive-index layer, the refractive index of the high-refractive-index layer, and the refractive index difference between the low-refractive-index layer and the high-refractive-index layer. When the reflective film 253 is composed of a metal film, the dependence of the intensity of the blue light LB emitted from the reflective film 253 on the angle of incidence changes depending on parameters such as the density of metal particles.

[0118] The spectral reflectance of the reflective film 253 is maximized at the wavelength at which human visual sensitivity is highest, thereby improving the visibility of the image projected by the projector 350. By adjusting the parameters of the dielectric multilayer film and metal film that constitute the reflective film 253, the wavelength at which the reflectance of the reflective film 253 is maximized can be effectively controlled.

[0119] As described above, for example, when the taper angle of the light guide element 143 is within the range of 7° to 22° or 14° to 36°, the reflective film 253 is designed such that the incident angle of blue light LB that results in the highest intensity of blue light LB emitted from the reflective surface 143r and the reflective film 253 is within a predetermined angle range, and the parameters of the dielectric multilayer film are appropriately determined. The predetermined angle range is, for example, 60° to 90°. The relationship between the incident angle of blue light LB to the reflective film 253 and the intensity of blue light LB emitted from the reflective film 253 can also be obtained by numerical simulation based on the configuration of the blue light emission unit 103 and ray tracing.

[0120] The parallelizing element 163 is provided on the optical path of the blue light LB emitted from the light guide element 143, positioned -D1 side of 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 blue light LB emitted from the light guide element 143 along the D1 direction. The parallelizing element 163 corresponds to the second parallelizing element.

[0121] The parallelizing element 163 is, for example, a plano-convex lens, and has an incident surface consisting of a flat surface perpendicular to the D1 direction and an exit surface consisting of a convex curved surface projecting toward the exit side of the red light LR. The focal point of the plano-convex lens constituting the parallelizing element 163 is at least on the +D1 side of the parallelizing element 163, and on the opposite side from 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.

[0122] The incident surface of the parallelizing element 163 is in contact with the exit end 143b of the light guide element 143. By having the parallelizing element 163 in contact with the exit end 143b, the blue light LB emitted from the exit end 143b of the light guide element 143 is captured to the maximum extent by the parallelizing element 163, and the loss of blue light LB is suppressed. However, the parallelizing element 163 may be an optical lens other than a plano-convex lens capable of parallelizing the incident blue light LB, and may be arranged at an appropriate distance from the light guide element 143 in the D1 direction.

[0123] The optical modulator 483 includes an incident polarizing element 173, an optical modulator 183, and an exit polarizing element 177. The optical modulator 483 corresponds to a second optical modulator and modulates the incident blue light LB based on image information transmitted from an externally located image forming apparatus such as a computer (not shown).

[0124] The incident polarizing element 173 is located on the optical path of the blue light LB emitted from the parallelizing element 163, and is positioned -D1 side of the parallelizing element 163, and overlapping with the parallelizing element 163 in the D2 and D3 directions. The incident polarizing element 173 is positioned, for example, with an appropriate gap between it and the optical modulation element 183 in the D1 direction, but it may also be in contact with the optical modulation element 183 from the +D1 side.

[0125] The incident polarizing element 173 emits a predetermined polarization of the blue light LB emitted from the parallelizing element 163 along the D1 direction towards the -D1 side. The predetermined polarization is, for example, S polarization. The incident polarizing element 173 is, for example, a reflective polarizer having a plate surface parallel to the planes including the D2 and D3 directions. The incident polarizing element 173 transmits a portion of the incident blue light LB, including the predetermined polarization, to the -D1 side and reflects the other portion of the blue light LB to the +D1 side.

[0126] The blue light LB emitted from the light source 123 contains at least P-polarized and S-polarized light, and is, for example, randomly polarized. The S-polarized component of the blue light LB emitted from the light source 123 passes sequentially through the light guide element 143 and the parallelizing element 163 as described above, passes through the incident polarizing element 173, and is emitted on the -D1 side of the incident polarizing element 173. The P-polarized component of the blue light LB passes sequentially through the light guide element 143 and the parallelizing element 163, similar to the S-polarized component, but is reflected at the incident plane of the incident polarizing element 173 and is emitted on the +D1 side of the incident polarizing element 173.

[0127] The optical modulation element 183 is positioned on the optical path of the blue light LB emitted from the incident polarizing element 173, -D1 side of the incident polarizing element 173, and overlapping with the incident polarizing element 173 in the D2 and D3 directions. The optical modulation element 183 modulates the blue light LB emitted from the incident polarizing element 173 based on image information transmitted from an externally connected image forming apparatus (not shown) to the optical modulation element 183.

[0128] The optical modulation element 183 is, for example, a transmissive liquid crystal panel. The liquid crystal panel constituting the optical modulation element 183 has a plurality of pixels (not shown). Each pixel is equipped with a switching element. The switching element is, for example, a TFT. The switching element of each pixel is supplied with an electrical signal corresponding to the brightness of blue light at the relative position of each pixel on the modulation plane of the optical modulation element 183 in the image projected by the projector 350. Each pixel modulates the vibration direction of the blue light LB incident from the incident polarizing element 173 by the operation of the switching element in accordance with the aforementioned electrical signal, and generates blue image light IB. Image light IB corresponds to the second light. The optical modulation element 183 emits the image light IB generated by the liquid crystal panel along the D1 direction toward the -D1 side.

[0129] The emission-side polarizing element 177 is located on the optical path of the image light IR emitted from the optical modulation element 183, and is positioned -D1 side of the optical modulation element 183, and overlaps with the optical modulation element 183 in the D2 and D3 directions.

[0130] A portion of the exit-side polarizing element 177 is positioned, for example, at an appropriate distance from the light modulation element 183 and the photosynthesis element 200 in the D1 direction. The remaining portion of the exit-side polarizing element 177 is in contact with the incident surface of the image light IB in the photosynthesis element 200, i.e., the incident surface 210e of the cross dichroic prism 210 (described later), from the +D1 side. Note that in Figure 1, a portion of the exit-side polarizing element 177 is omitted, and only the remaining portion of the exit-side polarizing element 177 is shown.

[0131] The output polarizing element 177 outputs a predetermined polarization of the image light IB emitted from the optical modulation element 183 along the D1 direction toward the -D1 side. The predetermined polarization is, for example, S polarization.

[0132] The exit-side polarizing element 177 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 exit-side polarizing element 177 transmits a portion of the incident image light IB, including a predetermined polarization, to the +D2 side, and reflects or absorbs the other portion of the image light IB to the -D2 side. If it is desired to suppress the generation of reflected light and stray light to the optical modulation element 183, it is desirable that the exit-side polarizing element 177 be an absorbing polarizer.

[0133] The photosynthetic element 200 is positioned in the region where the optical paths of the red image light IR emitted from the exit-side polarizing element 175, the green image light IG emitted from the exit-side polarizing element 176, and the blue image light IB emitted from the exit-side polarizing element 177 intersect. The photosynthetic element 200 synthesizes the image light IR, IG, and IB emitted from the exit-side polarizing elements 175, 176, and 177, and emits them towards the +D2 side along the D2 direction.

[0134] The photosynthetic element 200 is, for example, a so-called unpolarized cross dichroic prism 210 that does not have polarization dependence. The cross dichroic prism 210 has an incident surface 210c facing the exit surface of the exit polarizing element 175, an incident surface 210d facing the exit surface of the exit polarizing element 176, an incident surface 210e facing the exit surface of the exit polarizing element 177, an exit surface 210b, and two reflective films 211 and 212. The incident surfaces 210c and 210e are parallel to the plane including the D2 and D3 directions and overlap each other in the D2 and D3 directions. The incident surface 210d and the exit surface 210b are parallel to the plane including the D1 and D3 directions and overlap each other in the D1 and D3 directions.

[0135] The reflective film 211 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 212 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 films 211 and 212 overlap with the incident surfaces 210c and 210e in the D2 direction, and overlap with the ejection surface 210b and the incident surface 210d in the D3 direction.

[0136] The reflective film 211 reflects light in the blue wavelength band and transmits light in the green and red wavelength bands. The reflective film 212 reflects light in the red wavelength band and transmits light in the blue and green wavelength bands. The reflective films 211 and 212 are composed of, for example, dielectric multilayer films.

[0137] The cross dichroic prism 210 is constructed by aligning the right-angle vertices of four right-angle prisms with the center of the photosynthetic element 200 and bonding the right-angle surfaces together when viewed from the D3 direction. The four right-angle prisms of the cross dichroic prism 210 are made of a transparent material that transmits visible wavelength light.

[0138] The reflective film 211 is located on one of the intersecting surfaces of the four right-angle prisms, specifically the surface that moves from the +D2 side to the -D2 side as you move from the -D1 side to the +D1 side, as described above, and is composed of, for example, a dielectric multilayer film. The reflective film 212 is located on the other intersecting surface of the four right-angle prisms, specifically the surface that moves from the -D2 side to the +D2 side as you move from the -D1 side to the +D1 side, as described above.

[0139] The S-polarized red image light IR emitted from the exit polarizing element 175 enters the interior of the cross dichroic prism 210 from the incident surface 210c along the D1 direction toward the +D1 side, passes through the reflective film 211, is reflected by the reflective film 212, and propagates toward the +D2 side. The P-polarized green image light IG emitted from the exit polarizing element 176 enters the interior of the cross dichroic prism 210 from the incident surface 210d along the D2 direction toward the +D2 side, passes through the reflective films 211 and 212, and propagates straight toward the +D2 side. The S-polarized blue image light IB emitted from the exit polarizing element 177 enters the interior of the cross dichroic prism 210 from the incident surface 210e along the D1 direction toward the -D1 side, passes through the reflective film 212, is reflected by the reflective film 211, and propagates toward the +D2 side.

[0140] The image light IB, IG, and IR emitted from the reflective films 211 and 212 of the cross dichroic prism 210 toward the +D2 side are combined to generate full-color image light IM. The cross dichroic prism 210 emits full-color image light IM toward the +D2 side along the D2 direction from the emission surface 210b. An anti-reflective film 220 is provided on the emission surface 210b. The anti-reflective film 220 prevents reflection of the image light IM emitted from the emission surface 210b of the cross dichroic prism 210 toward the -D2 side, and emits almost all of the image light IM emitted from the emission surface 210b toward the +D2 side.

[0141] The projection optical system 390 is positioned on the optical path of the image light IM emitted from the photosynthetic element 200 of the optical module 310. The projection optical system 390 projects the image light IM emitted from the photosynthetic element 200 onto the screen SCR located on the +D2 side, and displays the image transmitted from the image forming apparatus to the optical modulation elements 181, 182, and 183 on the screen SCR in an enlarged view.

[0142] The projection optical system 390 is composed of, for example, one or more optical lenses arranged along the D2 direction. 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.

[0143] Figure 2 is a schematic diagram of the red light emission unit 101 and the optical modulation device 481 of the optical module 310 in this embodiment.

[0144] As shown in Figure 2, the incident polarizing element 171 of the optical modulator 481 has an anti-reflective coating 311, a phase difference plate 312, a reflective polarizing layer 313, an absorbing polarizing layer 314, and an anti-reflective coating 315. The anti-reflective coating 311, the phase difference plate 312, the reflective polarizing layer 313, the absorbing polarizing layer 314, and the anti-reflective coating 315 are arranged sequentially from the -D1 side to the +D1 side and are integrally formed with each other.

[0145] The anti-reflective coating 311 is provided on the incident surface of the red light LR on the phase difference plate 312 and is in contact with the -D1 side surface of the surface of the phase difference plate 312 that is parallel to the plane including the D2 and D3 directions. The anti-reflective coating 311 prevents reflection of the red light LR incident on the incident polarizing element 171 toward the -D1 side, and emits almost all of the incident red light LR toward the +D1 side and incident on the phase difference plate 312. As described later, the anti-reflective coating 311 also emits almost all of the red light LR incident from the +D1 side toward the -D1 side, and emits the red light LR from the incident polarizing element 171 toward the -D1 side.

[0146] The phase difference plate 312 corresponds to the first polarization conversion section and changes the polarization state of the red light LR incident on the incident polarizing element 171 and emitted from the anti-reflective coating 311. The phase difference plate 312 functions similarly to a λ / 4 wave plate, changing the polarization state of the incident red light LR, for example, converting linearly polarized light to circularly polarized light, or circularly polarized light to linearly polarized light.

[0147] The phase difference plate 312 is made of a quartz substrate 401. Because the phase difference plate 312 is made of a quartz substrate 401, the heat dissipation of the phase difference plate 312 is enhanced, and the direction of the crystal axis and the polarization separation characteristics can be easily set according to the thickness in the D1 direction. The thickness of the quartz substrate 401 in the D1 direction is, for example, 0.250 mm to 0.650 mm. This allows the polarization state of most of the red light LR incident on the quartz substrate 401 to be changed. The phase difference plate 312 may be formed from an anisotropic material having a crystal axis along a predetermined direction, and may be made from a substrate other than quartz, such as a sapphire single crystal.

[0148] The reflective polarizing layer 313 is provided on the red light LR emission surface of the phase difference plate 312 and is in contact with the +D1 side surface of the surface parallel to the plane including the D2 and D3 directions of the phase difference plate 312. The reflective polarizing layer 313 corresponds to the first polarization separation section and transmits the longitudinally polarized red light LRT of the red light LR that passes through the phase difference plate 312 and is emitted from the phase difference plate 312, and reflects the transversely polarized red light LRH of the red light LR that passes through the phase difference plate 312 and is emitted from the phase difference plate 312.

[0149] The red light LRT transmitted through the reflective polarization layer 313 corresponds to at least a portion of the first polarization component of the first light passing through the first polarization conversion section. The red light LRH reflected by the reflective polarization layer 313 corresponds to the other portion of the first polarization component of the first light passing through the first polarization conversion section. The vertically polarized red light LRT is, for example, S-polarized. The transversely polarized red light LRH is, for example, P-polarized.

[0150] The absorption polarization layer 314 is provided on the emission surface of the reflection polarization layer 313 and is in contact with the +D1 side surface of the surface of the reflection polarization layer 313 that includes the D2 and D3 directions. The absorption polarization layer 314 transmits the red light LRT that passes through the reflection polarization layer 313 and is emitted from the reflection polarization layer 313, and absorbs the red light LRH (not shown) that passes through the phase difference plate 312 and is emitted in small amounts from the phase difference plate 312. If the precision of the reflection polarization layer 313 is high and the amount of red light LRH emitted from the reflection polarization layer 313 on the +D1 side is sufficiently small, the absorption polarization layer 314 may be omitted.

[0151] The anti-reflective coating 315 is provided on the ejection surface of the absorption polarizing layer 314 and is in contact with the +D1 side surface of the surface along the plane including the D2 and D3 directions of the absorption polarizing layer 314. The anti-reflective coating 315 prevents reflection of red light LRT ejected from the absorption polarizing layer 314 and incident from the -D1 side toward the -D1 side, and ejects almost all incident red light LRT toward the +D1 side.

[0152] As described above, the optical modulation element 181 is composed of a transmissive liquid crystal panel and includes a counter substrate 322, a liquid crystal layer 324, a sealing material 325, and an element substrate 326. The counter substrate 322, the liquid crystal layer 324, the sealing material 325, and the element substrate 326 are integrally formed with each other.

[0153] The opposing substrate 322 and the element substrate 326 are arranged to face each other in the D1 direction via a frame-shaped sealing material 325. The liquid crystal layer 324 is positioned between the opposing substrate 322 and the element substrate 326 in the D1 direction and is surrounded by the sealing material 325 in the plane including the D2 and D3 directions.

[0154] A counter electrode is provided on the +D1 side surface of the opposing substrate 322, which is parallel to the plane including the D2 and D3 directions. Multiple pixel electrodes corresponding to multiple pixels and a switching element are provided on the -D1 side surface of the element substrate 326, which is parallel to the plane including the D2 and D3 directions. The multiple pixel electrodes face the counter electrode in the D1 direction via the liquid crystal layer 324.

[0155] The exit-side polarizing element 175 of the optical modulator 481 has an anti-reflective coating 331, an absorption polarizing layer 332, and a phase difference plate 333. The anti-reflective coating 331, the absorption polarizing layer 332, and the phase difference plate 333 are arranged sequentially from the -D1 side to the +D1 side and are integrally formed with each other. The +D1 side surface of the phase difference plate 333, which is parallel to the planes including the D2 and D3 directions, is in contact with the incident surface 210c of the cross dichroic prism 210 of the photosynthesis element 200 from the -D1 side.

[0156] The anti-reflective coating 331 prevents the reflection of red image light IR emitted from the optical modulation element 181 toward the -D1 side, and emits almost all incident image light IR toward the +D1 side. The absorption polarizing layer 332 is provided on the emission surface of the anti-reflective coating 331 and is in contact with the +D1 side surface of the anti-reflective coating 331 which is parallel to the plane including the D2 and D3 directions.

[0157] The absorbing polarizing layer 332 transmits image light IR with a predetermined polarization direction that passes through the anti-reflective film 331 and is emitted from the anti-reflective film 331, and absorbs image light IR with polarization directions other than the predetermined polarization direction that passes through the anti-reflective film 331 and is emitted in small amounts from the anti-reflective film 331. If the amount of image light IR with polarization directions other than the predetermined polarization direction emitted from the anti-reflective film 331 to the +D1 side is sufficiently small, the absorbing polarizing layer 332 may be omitted.

[0158] The phase difference plate 333 changes the polarization state of the image light IR emitted from the absorption polarizing layer 332. The phase difference plate 333 functions similarly to a λ / 4 wave plate, changing the polarization state of the incident image light IR, for example, converting linearly polarized light to circularly polarized light. The phase difference plate 333 is made of, for example, a quartz substrate.

[0159] Figure 2 shows an example of the principal ray of the red light LR emitted from the light-emitting element 421 of the light source 121, which enters the light guide element 141 from the incident end 141a and propagates directly to the exit end 141b without ever entering the reflective surface 141r.

[0160] The red light LR emitted from a position PR1 on the light-emitting surface of the light-emitting element 421 toward the +D1 side is unpolarized red light LRN, which includes S-polarized and P-polarized light. It enters the light guide element 141 from the incident end 141a, is guided toward the +D1 side by the light guide element 141, and is emitted from the exit end 141b. The red light LRN emitted from the light guide element 141 is parallelized along the D1 direction by the parallelizing element 161, enters the incident polarizing element 171, and passes through the anti-reflective coating 311 of the incident polarizing element 171.

[0161] Red light LRN passing through the anti-reflective coating 311 is incident on the phase difference plate 312 from the -D1 side and passes through the phase difference plate 312 from the -D1 side to the +D1 side. The polarization state of the red light LRN changes as it passes through the phase difference plate 312, for example, the ratio of S-polarized and P-polarized light contained in the red light LRN changes. However, the polarization conversion by the phase difference plate 312 acts on the red light LR that returns to the phase difference plate 312 by the reflective polarization layer 313. Of the red light LRN emitted from the phase difference plate 312 and incident on the reflective polarization layer 313, the vertically polarized red light LRT sequentially passes through the reflective polarization layer 313, the absorbing polarization layer 314, and the anti-reflective coating 315, and is emitted from the incident polarizing element 171 to the +D1 side.

[0162] Of the red light LRN emitted from the phase difference plate 312 and incident on the reflection polarization layer 313, the transversely polarized red light LRH is reflected by the reflection polarization layer 313, incident on the phase difference plate 312 again from the +D1 side, and is converted into circularly polarized red light LRC by passing through the phase difference plate 312. The red light LRC contains S-polarized and P-polarized light in approximately a 1:1 ratio. The red light LRC emitted from the phase difference plate 312 toward the -D1 side passes through the anti-reflective film 311 and is emitted toward the -D1 side from the incident polarizing element 171.

[0163] The red light LRC emitted from the incident polarizing element 171 to the -D1 side passes through the parallelizing element 161, enters the light guide element 141 from the exit end 141b, is guided to the -D1 side by the light guide element 141, and is emitted from the incident end 141a. At least a portion of the red light LRC emitted from the light guide element 141 to the -D1 side is reflected to the +D1 side at a position PR2 different from position PR1 on the light-emitting surface of the light-emitting element 421 of the light source 121. When reflected from the light-emitting surface of the light-emitting element 421, the polarization state of the red light LRC does not change and remains circularly polarized.

[0164] The red light LRC reflected from the light-emitting surface of the light-emitting element 421 of the light source 121 toward the +D1 side enters the light guide element 141 from the incident end 141a, is guided toward the +D1 side by the light guide element 141, and is emitted from the exit end 141b. The red light LRC emitted from the light guide element 141 is parallelized along the D1 direction by the parallelizing element 161, enters the incident polarizing element 171, and passes through the anti-reflective coating 311 of the incident polarizing element 171.

[0165] Red light LRC transmitted through the anti-reflective coating 311 is incident on the phase difference plate 312 from the -D1 side and passes through the phase difference plate 312 from the -D1 side to the +D1 side. The polarization state of the red light LRC changes as it passes through the phase difference plate 312 and is converted into vertically polarized red light LRT. The red light LRT emitted from the phase difference plate 312 and incident on the reflective polarization layer 313 sequentially passes through the reflective polarization layer 313, the absorption polarization layer 314, and the anti-reflective coating 315, and is emitted from the incident polarizing element 171 to the +D1 side. The direction of vibration of the red light LRT emitted from the incident polarizing element 171 to the +D1 side is, for example, parallel to the D2 direction.

[0166] The red light LRT emitted from the incident polarizing element 171 towards +D1 is converted into image light IR by the optical modulation element 181. The vibration direction of the image light IR emitted from the optical modulation element 181 towards +D1 is, for example, parallel to the D1 direction. As described above, the vibration direction of the image light IR emitted from the exit polarizing element 175 towards +D1 includes, for example, multiple directions.

[0167] Image light IR with a predetermined polarization direction, emitted from the optical modulation element 181 and incident on the emission-side polarizing element 175 from the -D1 side, passes through the anti-reflective film 331 and the absorption polarizing layer 332 and is incident on the phase difference plate 333. Image light IR with a predetermined polarization direction incident on the phase difference plate 333 from the -D1 side is converted to circular polarization. Image light IR emitted from the emission-side polarizing element 175 to the +D1 side is incident on the cross dichroic prism 210 of the photosynthesis element 200 from the incident surface 210c, as described above.

[0168] Figure 3 is a schematic diagram of the phase difference plate 312 of the incident polarizing element 171 of the optical modulation device 481. As shown in Figure 3, the quartz substrate 401 forming the phase difference plate 312 includes, for example, a first quartz substrate 411 and a second quartz substrate 412. The first quartz substrate 411 is located on the -D1 side of the quartz substrate 401. The thickness of the first quartz substrate 411 in the D1 direction is, for example, 0.300 mm to 0.400 mm.

[0169] The second crystal substrate 412 is provided on the +D1 side of the plate surface of the first crystal substrate 411, which is parallel to the plane including the D2 and D3 directions, and is in contact with the first crystal substrate 411 in the D1 direction and is integrally formed with the first crystal substrate 411. The thickness of the second crystal substrate 412 in the D1 direction is, for example, 0.100 mm to 0.200 mm. However, the thickness of the first crystal substrate 411 in the D1 direction and the thickness of the second crystal substrate 412 in the D1 direction are not limited to the above values. For example, the thickness of the first crystal substrate 411 in the D1 direction can be 0.200 mm to 0.400 mm, and the thickness of the second crystal substrate 412 in the D1 direction can be 0.200 mm to 0.400 mm.

[0170] Figure 4 is a schematic diagram of the phase difference plate 312 and the reflective polarizing layer 313 as viewed from the -D1 side along the D1 direction. In Figure 4, the reflective polarizing layer 313 is shown larger than the phase difference plate 312 when viewed along the D1 direction in order to clearly show the positional relationship between the phase difference plate 312 and the reflective polarizing layer 313.

[0171] The first quartz substrate 411 has a first crystal axis J11. The transmission axis J1 of the reflective polarizing layer 313 is, for example, parallel to the D2 direction. When viewed along the D1 direction, the first crystal axis J11 is inclined with respect to the D2 and D3 directions and forms a predetermined angle θ11 with respect to the transmission axis J1 of the reflective polarizing layer 313. The angle θ11 is, for example, 15°. Since the thickness of the first quartz substrate 411 is set to 0.3 mm to 0.4 mm as described above, the angle that the first crystal axis J11 makes with respect to the transmission axis J1 can be easily set to a predetermined angle such as 15°.

[0172] The second quartz substrate 412 has a second crystal axis J12. The second crystal axis J12 is inclined with respect to the D2 and D3 directions when viewed along the D1 direction, and forms a predetermined angle θ12 with respect to the transmission axis J1 of the reflective polarizing layer 313. The angle θ12 is, for example, 75°. Since the thickness of the second quartz substrate 412 is set to 0.1 mm to 0.2 mm as described above, the angle that the second crystal axis J12 makes with respect to the transmission axis J1 can be easily set to a predetermined angle such as 75°. However, the angle that the first crystal axis J11 makes with respect to the transmission axis J1, and the angle that the second crystal axis J12 makes with respect to the transmission axis J1 are not limited to those described above. For example, if the thickness of the first quartz substrate 411 in the D1 direction is 0.300 mm to 0.400 mm, and the thickness of the second quartz substrate 412 in the D1 direction is 0.300 mm to 0.400 mm, the angle that the first crystal axis J11 makes with respect to the transmission axis J1 can be set to 45°, and the angle that the second crystal axis J12 makes with respect to the transmission axis J1 can be set to 135°.

[0173] The crystal axis J2 of the quartz substrate 401 forms an angle of approximately 45° with respect to the transmission axis J1 of the reflective polarization layer 313, due to the combination of the angle that the first crystal axis J11 makes with respect to the transmission axis J1 and the angle that the second crystal axis J12 makes with respect to the transmission axis J1. The angle θ1 that the crystal axis J2 makes with respect to the transmission axis J1 is preferably 45°, which is used to effectively change the polarization state of the red light LRN and LRC incident on the quartz substrate 401, and is appropriately set so that the ratio of vertically polarized light to transversely polarized light in the red light LR emitted from the quartz substrate 401, which is the phase difference plate 312, to the reflective polarization layer 313 is a predetermined ratio such as 1:1.

[0174] The angles that the first crystal axis J11, the second crystal axis J12, and the crystal axis of the quartz substrate 401 make with respect to the transmission axis J1 of the reflective polarizing layer 313 represent the narrow angles that each crystal axis makes counterclockwise with respect to an unillustrated imaginary line that extends from the optical axis AXR of the red light LR incident on the reflective polarizing layer 313 of the incident polarizing element 171, overlapping with the transmission axis J1 and extending towards the +D2 side, when viewed from the -D1 side along the D1 direction.

[0175] The angles θ11 and θ12 are set appropriately according to angle θ1, taking into account the spectrum of red light LR emitted from the light source 121 and incident on the phase difference plate 312 of the incident polarizing element 171 of the optical modulator 481. The thickness of the first quartz substrate 411 is set appropriately according to angle θ11. The thickness of the second quartz substrate 412 is set appropriately according to angle θ12.

[0176] Figure 5 is a graph showing an example of numerical calculation results for the phase modulation amount of a single-layer quartz substrate 401 forming a phase difference plate 312, and how this phase modulation amount changes with respect to red light LR with respect to the thickness of the quartz substrate 401 in the D1 direction, as well as the spectral results of the red light LR incident on the quartz substrate 401. In this numerical calculation, the thickness of the quartz substrate 401 in the D1 direction was varied to 0.296 mm, 0.470 mm, and 0.609 mm.

[0177] In Figure 5, the phase modulation amount at the quartz substrate 401 represents the relative value when the phase modulation amount that adds a phase difference of λ / 4, i.e., a phase difference of π / 2, to the red light LR incident on the quartz substrate 401 is defined as 100%. In the same figure, the spectrum of the red light LR incident on the quartz substrate 401 is schematically shown as the relative values ​​of the light intensity of the red light LR for each wavelength on the horizontal axis, which is common to the phase modulation amount of the quartz substrate 401, in order to clearly show the relative relationship with the phase modulation amount of the quartz substrate 401.

[0178] As shown in Figure 5, the red light LR incident on the quartz substrate 401 has its main emission peak in the red wavelength band, for example, 600 nm to 650 nm. The peak wavelength of the red light LR is, for example, approximately 630 nm. The wavelength band that satisfies the half-value of the red light LR spectrum is approximately 618 nm to 638 nm.

[0179] As the thickness of the quartz substrate 401 is successively increased from 0.296 mm to 0.470 mm and 0.609 mm, the peak wavelength of the phase modulation profile of the quartz substrate 401 remains almost unchanged, at approximately 630 nm, which is close to the peak wavelength of the red light LR spectrum. However, as the thickness of the quartz substrate 401 is successively increased from 0.296 mm to 0.470 mm and 0.609 mm, the wavelength band that satisfies half of the phase modulation profile of the quartz substrate 401 decreases successively.

[0180] When the thickness of the quartz substrate 401 is 0.296 mm and 0.470 mm, almost the entire wavelength band that satisfies the half-value of the red light LR spectrum is included in the wavelength band that satisfies the half-value of the phase modulation profile of the quartz substrate 401. Therefore, considering the spectrum of red light LR, and assuming that the angle θ1 that the crystal axis J2 of the quartz substrate 401 makes with the transmission axis J1 of the reflection polarization layer 313 is 45°, when the thickness of the quartz substrate 401 is 0.296 mm and 0.470 mm, the polarization state of almost the entire amount of red light LR incident on the quartz substrate 401 changes as expected, and the amount of longitudinally polarized red light LR emitted from the reflection polarization layer 313 is relatively large.

[0181] When the thickness of the quartz substrate 401 is 0.609 mm, only a portion of the wavelength band that satisfies the half-value of the red light LR spectrum is included in the wavelength band that satisfies the half-value of the phase modulation profile of the quartz substrate 401. Therefore, considering and assuming the same as above, when the thickness of the quartz substrate 401 is 0.609 mm, the polarization state of only a portion of the red light LR incident on the quartz substrate 401 changes as expected, but the amount of longitudinally polarized red light LR emitted from the reflective polarization layer 313 is relatively small.

[0182] Figure 6 is a graph showing an example of numerical calculation results for the phase modulation amount of the crystal substrate 401 and the spectrum of red light LR incident on the crystal substrate 401, where the thickness of the first crystal substrate 411 in the D1 direction is 0.313 mm, the thickness of the second crystal substrate 412 in the D1 direction is 0.157 mm, and the total thickness of the crystal substrate 401 in the D1 direction is 0.470 mm, and the internal temperature of the projector 350 casing is 25°C.

[0183] For reference, this numerical calculation also shows the numerical calculation results for the amount of phase modulation when the thickness of the crystal substrate 401 in the D1 direction is increased by approximately +1.5 μm, and when the thickness of the crystal substrate 401 is 0.470 mm and the internal temperature of the projector 350's casing is 85°C.

[0184] As shown in Figures 5 and 6, when the thickness of the quartz substrate 401 is a common 0.470 mm, the full width at half maximum of the phase modulation profile of the quartz substrate 401 is expanded to approximately 83 nm when it is composed of two laminated quartz substrates, the first quartz substrate 411 and the second quartz substrate 412, compared to approximately 20 nm when the quartz substrate 401 is composed of a single sheet.

[0185] If the thickness of the crystal substrate 401 is 0.470 mm, then if the crystal substrate 401 is made of a single sheet, as described above, the polarization state of the main red light LR in the wavelength band that satisfies at least half value to the maximum value of the red light LR spectral profile can be changed by the crystal substrate 401 of the phase difference plate 312. By making the crystal substrate 401 of a single sheet, the cost of the crystal substrate 401 and the projector 350 can be reduced.

[0186] If the thickness of the quartz substrate 401 is 0.470 mm, and the quartz substrate 401 is constructed by bonding two sheets together as described above, the polarization state of the red light LR across the entire wavelength band that satisfies the minimum value of the red light LR light intensity, i.e., between zero and the maximum value, can be changed by the quartz substrate 401 of the phase difference plate 312. This improves the polarization conversion capability of the quartz substrate 401 compared to when the quartz substrate 401 is constructed as a single sheet.

[0187] As shown in Figure 6, when the quartz substrate 401 is constructed by bonding two sheets together as described above, even if the thickness of the quartz substrate 401 increases by +1.5 μm, or if the ambient temperature around the quartz substrate 401 in the projector 350 changes from 25°C to 85°C, the full width at half maximum of the phase modulation profile of the quartz substrate 401 does not change significantly, and the polarization state of the red light LR across the entire wavelength band that satisfies the minimum and maximum values ​​of the red light LR light intensity can be changed by the quartz substrate 401.

[0188] Whether the quartz substrate 401 is constructed as a single sheet or as a laminated structure of a first quartz substrate 411 and a second quartz substrate 412 can be determined based on the wavelength dependence of the phase modulation amount of the quartz substrate 401, taking into account each configuration, and the numerical calculation results of the spectrum of the red light LR emitted from the light source 121 and incident on the quartz substrate 401, as in the example described above. Furthermore, the angle θ1 that the crystal axis of the quartz substrate 401 makes with respect to the transmission axis of the reflective polarization layer 313, and the thickness of the quartz substrate 401 in the D1 direction can also be appropriately set based on the numerical calculation results. Note that the phase difference plate 312 may have two or more quartz substrates, and two or more quartz substrates may be laminated in the D1 direction.

[0189] Figure 7 is a schematic diagram of the green light emission unit 102 and the optical modulation device 482 of the optical module 310 in this embodiment.

[0190] As shown in Figure 7, the light-emitting element 422 of the light source 122 includes, for example, an LED body 124 made of a semiconductor and a phosphor 125. The LED body 124 includes, for example, a GaN-based semiconductor material having excellent light extraction efficiency and emits blue light. The blue light emitted from the LED body 124 corresponds to the fourth light. The type and material of the LED body, and the type and material of the phosphor 125 are appropriately selected so that the phosphor excited by the light emitted from the LED body 124 emits green light LG in the green wavelength band.

[0191] The phosphor 125 is laminated on the +D2 side emission surface of the LED body 124. The phosphor 125 corresponds to a wavelength conversion element and is excited by the light emitted from the LED body as excitation light, and emits green light LG as fluorescence from the emission surface. As mentioned above, when the LED body emits blue light, the phosphor is, for example, a translucent ceramic, such as cerium-doped yttrium aluminum garnet (YAG:Ce 3+ ) includes.

[0192] The incident polarizing element 172 of the optical modulation device 482 includes a phase difference plate 342, a reflective polarizing layer 343, an absorbing polarizing layer 344, and an anti-reflective film 345. The phase difference plate 342, the reflective polarizing layer 343, the absorbing polarizing layer 344, and the anti-reflective film 345 are arranged sequentially from the -D2 side to the +D2 side and are integrally formed with each other.

[0193] The phase difference plate 342 acts as a polarization conversion unit, changing the polarization state of the green light LG incident on the incident polarizing element 172. The phase difference plate 342 functions similarly to a λ / 4 wave plate, changing the polarization state of the incident green light LG, for example, converting linearly polarized light to circularly polarized light, or circularly polarized light to linearly polarized light.

[0194] The phase difference plate 342 is made of a quartz substrate 402. Because the phase difference plate 342 is made of a quartz substrate 402, the heat dissipation of the phase difference plate 342 is enhanced, and the direction of the crystal axis and the polarization separation characteristics can be easily set according to the thickness in the D2 direction. The phase difference plate 342 may be formed from an anisotropic material having a crystal axis along a predetermined direction, and may be made from a substrate other than quartz, such as a sapphire single crystal.

[0195] The reflective polarizing layer 343 is provided on the green light LG emission surface 342b of the phase difference plate 342 and is in contact with the +D2 side surface of the surface parallel to the plane including the D1 and D3 directions of the phase difference plate 342. The reflective polarizing layer 343 acts as a polarization separation section, transmitting the vertically polarized green light LGT of the green light LG that passes through the phase difference plate 312 and is emitted from the phase difference plate 342, and reflecting the transversely polarized green light LGH of the green light LG that passes through the phase difference plate 342 and is emitted from the phase difference plate 342. The vertically polarized green light LRT is, for example, P-polarized. The transversely polarized green light LGH is, for example, S-polarized.

[0196] The absorbing polarizing layer 344 is provided on the emission surface of the reflective polarizing layer 343 and is in contact with the +D2 side surface of the surface of the reflective polarizing layer 343 that includes the D1 and D3 directions. The absorbing polarizing layer 344 transmits the green light LGT that passes through the reflective polarizing layer 343 and is emitted from the reflective polarizing layer 343, and absorbs the green light LGH (not shown) that passes through the phase difference plate 342 and is emitted in small amounts from the phase difference plate 342. If the precision of the reflective polarizing layer 343 is high and the amount of green light LGH emitted from the reflective polarizing layer 343 on the +D2 side is sufficiently small, the absorbing polarizing layer 344 may be omitted.

[0197] The anti-reflective coating 345 is provided on the ejection surface of the absorption polarizing layer 344 and is in contact with the +D2 side surface of the surface along the plane including the D1 and D3 directions of the absorption polarizing layer 344. The anti-reflective coating 345 prevents reflection of green light LGT ejected from the absorption polarizing layer 344 and incident from the -D2 side toward the -D2 side, and ejects almost all incident green light LGT toward the +D2 side.

[0198] As described above, the optical modulation element 182 is composed of a transmissive liquid crystal panel and includes a counter substrate 352, a liquid crystal layer 354, a sealing material 355, and an element substrate 356. The counter substrate 352, the liquid crystal layer 354, the sealing material 355, and the element substrate 356 are integrally formed with each other.

[0199] The opposing substrate 352 and the element substrate 356 are arranged to face each other in the D2 direction via a frame-shaped sealing material 355. The liquid crystal layer 354 is positioned between the opposing substrate 352 and the element substrate 356 in the D2 direction and is surrounded by the sealing material 355 in a plane including the D1 and D3 directions.

[0200] A counter electrode is provided on the +D2 side surface of the opposing substrate 352, which is parallel to the plane including the D1 and D3 directions. Multiple pixel electrodes corresponding to multiple pixels and a switching element are provided on the -D2 side surface of the element substrate 356, which is parallel to the plane including the D1 and D3 directions. The multiple pixel electrodes face the counter electrode in the D2 direction via the liquid crystal layer 324.

[0201] The exit-side polarizing element 176 of the optical modulator 482 has an anti-reflective coating 361, an absorption polarizing layer 362, and a phase difference plate 363. The anti-reflective coating 361, the absorption polarizing layer 362, and the phase difference plate 363 are arranged sequentially from the -D2 side to the +D2 side and are integrally formed with each other. The +D2 side surface of the phase difference plate 363, which is parallel to the planes including the D1 and D3 directions, is in contact with the incident surface 210d of the cross dichroic prism 210 of the photosynthesis element 200 from the -D2 side.

[0202] The anti-reflective coating 361 prevents the reflection of the green image light IG emitted from the optical modulation element 182 toward the -D2 side, and emits almost all of the incident image light IG toward the +D2 side. The absorption polarization layer 362 is provided on the emission surface of the anti-reflective coating 361 and is in contact with the +D2 side surface of the anti-reflective coating 361 which is parallel to the plane including the D1 and D3 directions.

[0203] The absorbing polarizing layer 362 transmits image light IG with a predetermined polarization direction that passes through the anti-reflective film 361 and is emitted from the anti-reflective film 361, and absorbs image light IG with a polarization direction other than the predetermined polarization direction that passes through the anti-reflective film 361 and is emitted in small amounts from the anti-reflective film 361. If the amount of image light IG with a polarization direction other than the predetermined polarization direction emitted from the anti-reflective film 361 to the +D2 side is sufficiently small, the absorbing polarizing layer 362 may be omitted.

[0204] The phase difference plate 363 changes the polarization state of the image light IG emitted from the absorption polarizing layer 362. The phase difference plate 363 functions similarly to a λ / 4 wave plate, changing the polarization state of the incident image light IG, for example, converting linearly polarized light to circularly polarized light. The phase difference plate 363 is made of, for example, a quartz substrate.

[0205] Figure 7 shows an example of the principal ray of the green light LG emitted from the emission surface 125a of the phosphor 125 in the light-emitting element 422 of the light source 122, which enters the light guide element 142 from the incident end 142a and propagates directly to the emission end 142b without ever entering the reflective surface 142r.

[0206] The green light LG emitted from position PG1 on the emission surface 125a of the phosphor 125 toward the +D2 side is unpolarized green light LGN, which includes S-polarized and P-polarized light, incident on the light guide element 142 from the incident end 142a, guided toward the +D2 side by the light guide element 142, and emitted from the emission end 142b. The green light LGN emitted from the light guide element 142 is parallelized along the D2 direction by the parallelizing element 162 and incident on the phase difference plate 342 of the incident polarizing element 172.

[0207] Green light LGN incident on the phase difference plate 342 from the -D2 side passes through the phase difference plate 312 from the -D1 side to the +D1 side. The polarization state of the green light LGN changes as it passes through the phase difference plate 342, and the ratio of S-polarized to P-polarized light contained in the green light LGN changes. The vertically polarized green light LGT of the green light LGN emitted from the phase difference plate 342 and incident on the reflective polarization layer 343 sequentially passes through the reflective polarization layer 343, the absorbing polarization layer 344, and the anti-reflective film 345, and is emitted from the incident polarizing element 172 to the +D2 side.

[0208] Of the green light LGN emitted from the phase difference plate 342 and incident on the reflection polarization layer 343, the transversely polarized green light LGH is reflected by the reflection polarization layer 343, incident on the phase difference plate 342 again from the +D2 side, and is converted into circularly polarized green light LGC by passing through the phase difference plate 342. The green light LGC contains S-polarized and P-polarized light in approximately a 1:1 ratio. The green light LGC emitted from the phase difference plate 342 to the -D2 side is emitted from the incident polarizing element 172 to the -D2 side.

[0209] The green light LGC emitted from the incident polarizing element 172 to the -D2 side passes through the parallelizing element 162, enters the light guide element 142 from the exit end 142b, is guided to the -D2 side by the light guide element 142, and is emitted from the incident end 142a. The green light LGC emitted from the light guide element 142 to the -D2 side enters a position PG2 that is different from position PG1 on the exit surface 125a of the phosphor 125 in the light-emitting element 422 of the light source 122.

[0210] The phosphor 125 is excited by green light LGC incident from the +D2 side, and emits unpolarized green light LGN from position PG2 on the emission surface 125a towards the +D2 side.

[0211] The green light LGN emitted from position PG2 on the emission surface 125a of the phosphor 125 toward the +D2 side is guided from the -D2 side to the +D1 side by the light guide element 142, similar to the green light LGN emitted from position PG1 toward the +D2 side, and is emitted from the emission end 142b. The green light LGN emitted from the light guide element 142 is parallelized along the D2 direction by the parallelization element 162 and incident on the phase difference plate 342 of the incident polarizing element 172.

[0212] Green light LGN incident from the -D2 side on the -D2 side incident surface 342a, which is parallel to the plane including the D1 and D3 directions in the phase difference plate 342, passes through the phase difference plate 342 from the -D2 side to the +D2 side. The polarization state of green light LGN changes as it passes through the phase difference plate 342, and it is converted into vertically polarized green light LRT and transversely polarized green light LGH. Green light LGT emitted from the phase difference plate 342 and incident on the reflective polarizing layer 343 sequentially passes through the reflective polarizing layer 343, the absorbing polarizing layer 344, and the anti-reflective film 345, and is emitted from the incident polarizing element 172 to the +D2 side. The vibration direction of green light LGT emitted from the incident polarizing element 172 to the +D2 side is, for example, parallel to the D2 direction.

[0213] The green light LGH emitted from the phase difference plate 342 and reflected by the reflective polarizing layer 343, as described above, is again incident on the phase difference plate 342 from the +D2 side, passes through the phase difference plate 342 and is converted into circularly polarized green light LGC, which is then emitted from the incident polarizing element 172 to the -D2 side. The green light LGC emitted from the incident polarizing element 172 to the -D2 side, as described above, passes through the parallelizing element 162 and is guided from the +D2 side to the -D2 side by the light guide element 142, and is incident on the phosphor 125 of the light source 122 from the +D2 side.

[0214] Green light LGC incident on the phosphor 125 from the +D2 side contributes to the re-excitation of the phosphor 125, and green light LGN is emitted from the emission surface 125a of the phosphor 125 towards the +D2 side. In the green light emission section 102, the above-described behavior of green light LGC, LGH, LGN, and LGT repeatedly occurs.

[0215] The green light LGT emitted from the incident polarizing element 172 to the +D2 side is converted into image light IG by the optical modulator 182. The direction of vibration of the image light IG emitted from the optical modulator 182 to the +D2 side is, for example, parallel to the D1 direction. As described above, the direction of vibration of the image light IG emitted from the exit polarizing element 176 to the +D2 side includes, for example, multiple directions.

[0216] Image light IG with a predetermined polarization direction, emitted from the optical modulation element 182 and incident on the emission-side polarizing element 176 from the -D2 side, passes through the anti-reflective film 361 and the absorption polarizing layer 362 and is incident on the phase difference plate 363. Image light IG with a predetermined polarization direction incident on the phase difference plate 363 from the -D2 side is converted to circular polarization. As described above, the circularly polarized image light IG emitted from the emission-side polarizing element 176 to the +D2 side is incident on the cross dichroic prism 210 of the photosynthesis element 200 from the incident surface 210d.

[0217] Furthermore, the angle between the crystal axis of the quartz substrate 402 forming the phase difference plate 342 of the incident polarizing element 172 and the transmission axis of the reflective polarizing layer 343, the thickness of the quartz substrate 402 in the D2 direction, and whether the quartz substrate 402 is made of a single sheet or two sheets bonded together can be determined based on the wavelength dependence of the phase modulation amount of the quartz substrate 402 considering each configuration, and the numerical calculation results of the spectrum of the green light LG emitted from the light source 122 and incident on the quartz substrate 402. The phase difference plate 342 may have two or more quartz substrates, and two or more quartz substrates may be laminated in the D2 direction.

[0218] Figure 8 is a schematic diagram of the blue light emission unit 103 and the optical modulation device 483 of the optical module 310 in this embodiment.

[0219] As shown in Figure 8, the incident polarizing element 173 of the optical modulator 483 has an anti-reflective coating 371, a phase difference plate 372, an absorption polarizing layer 374, and an anti-reflective coating 375. The anti-reflective coating 371, the phase difference plate 372, the absorption polarizing layer 374, and the anti-reflective coating 375 are arranged sequentially from the +D1 side to the -D1 side and are integrally formed with each other.

[0220] The anti-reflective coating 371 is provided on the incident surface of the blue light LB on the phase difference plate 372 and is in contact with the +D1 side surface of the phase difference plate 372, which is parallel to the plane including the D2 and D3 directions. The anti-reflective coating 371 prevents reflection of the blue light LB incident on the incident polarizing element 173 toward the +D1 side, and directs almost all of the incident blue light LB toward the -D1 side and incident on the phase difference plate 372. The anti-reflective coating 371 also directs almost all of the blue light LB incident from the -D1 side toward the +D1 side, causing the incident polarizing element 173 to direct the blue light LB toward the +D1 side.

[0221] The phase difference plate 372 corresponds to the second polarization conversion section and changes the polarization state of the blue light LB that is incident on the incident polarizing element 173 and emitted from the anti-reflective coating 371. The phase difference plate 372 functions similarly to a λ / 4 wave plate, changing the polarization state of the incident blue light LB, for example, converting linearly polarized light to circularly polarized light, or circularly polarized light to linearly polarized light.

[0222] The phase difference plate 372 is made of a quartz substrate 403. Because the phase difference plate 372 is made of a quartz substrate 403, the heat dissipation of the phase difference plate 372 is enhanced, and the direction of the crystal axis and the polarization separation characteristics can be easily set according to the thickness in the D1 direction. The phase difference plate 372 may be formed from an anisotropic material having a crystal axis along a predetermined direction, and may be made from a substrate other than quartz, such as a sapphire single crystal.

[0223] Although not shown in the diagram, the phase difference plate 372 may be composed of two crystal substrates stacked on top of each other in the D1 direction. When the phase difference plate 372 is composed of two substrates bonded together as described above, the first crystal substrate located on the +D1 side corresponds to the third crystal substrate. In the same case, the second crystal substrate located on the -D1 side corresponds to the fourth crystal substrate.

[0224] Furthermore, as will be described later, when a reflective polarizing layer (not shown) is provided on the incident polarizing element 173, the crystal axis of the phase difference plate 372 forms a predetermined angle with respect to the transmission axis of the reflective polarizing layer when viewed along the D1 direction. The predetermined angle is, for example, 75°. When the phase difference plate 372 is composed of two plates bonded together as described above, the crystal axis of the quartz substrate placed on the +D1 side corresponds to the third crystal axis and forms an angle of, for example, 45° with respect to the transmission axis of the reflective polarizing layer. The crystal axis of the quartz substrate placed on the -D1 side corresponds to the fourth crystal axis and forms an angle of, for example, 135° with respect to the transmission axis of the reflective polarizing layer. However, the angle between the crystal axis of the quartz substrate placed on the +D1 side and the transmission axis of the reflective polarizing layer, and the angle between the crystal axis of the quartz substrate placed on the -D1 side and the transmission axis of the reflective polarizing layer are not limited to those described above. For example, the angle between the crystal axis of the quartz substrate placed on the +D1 side and the transmission axis of the reflective polarizing layer can be set to 15°, and the angle between the crystal axis of the quartz substrate placed on the -D1 side and the transmission axis of the reflective polarizing layer can be set to 75°.

[0225] A reflective polarizing layer (not shown) is provided on the red light LR emission surface of the phase difference plate 372 and is in contact with the -D1 side surface of the surface parallel to the plane including the D2 and D3 directions of the phase difference plate 372. For example, in the D1 direction, the reflective polarizing layer (not shown) is positioned between the phase difference plate 372 and the absorbing polarizing layer 374. The reflective polarizing layer (not shown) corresponds to the second polarization separation section and transmits the longitudinally polarized blue light LBT of the blue light LB that passes through the phase difference plate 372 and is emitted from the phase difference plate 372, and reflects the transversely polarized blue light LBH of the blue light LB that passes through the phase difference plate 372 and is emitted from the phase difference plate 372.

[0226] In more detail, if the reliability of the light-emitting element 423 of the light source 123 is high and the amount of blue light LB emitted from the light source 123 is sufficiently greater than the amount of blue light LB emitted from the light source 121 and the amount of green light LG emitted from the light source 122, the reflective polarization layer between the phase difference plate 372 and the absorption polarization layer 374 may be omitted, as shown in Figure 8. If the amount of blue light LB is about the same as the amount of red light LR, it is desirable to include a reflective polarization layer (not shown).

[0227] The blue light LBT transmitted through the reflective polarization layer (not shown) corresponds to at least a portion of the second polarization component of the second light passing through the second polarization conversion section. The blue light LBH reflected by the reflective polarization layer (not shown) corresponds to the other portion of the second polarization component of the second light passing through the second polarization conversion section. Longitudinally polarized blue light LBT is, for example, S-polarized. Transversely polarized blue light LBH is, for example, P-polarized.

[0228] The absorbing polarizing layer 374 is provided on the exit surface of the phase difference plate 372 and is in contact with the -D1 side surface of the surface of the reflective polarizing layer 313 that includes the D2 and D3 directions. The absorbing polarizing layer 374 transmits the blue light LBT emitted from the phase difference plate 372 and absorbs the blue light LBH (not shown) that is slightly emitted from the phase difference plate 372.

[0229] The anti-reflective coating 375 is provided on the ejection surface of the absorption polarizing layer 374 and is in contact with the -D1 side surface of the surface along the plane including the D2 and D3 directions of the absorption polarizing layer 374. The anti-reflective coating 375 prevents the reflection of blue light LBT ejected from the absorption polarizing layer 374 and incident from the -D1 side to the +D1 side, and ejects almost all incident blue light LBT to the -D1 side.

[0230] As described above, the optical modulation element 183 is composed of a transmissive liquid crystal panel and includes a counter substrate 382, ​​a liquid crystal layer 384, a sealing material 385, and an element substrate 386. The counter substrate 382, ​​the liquid crystal layer 384, the sealing material 385, and the element substrate 386 are integrally formed with each other.

[0231] The opposing substrate 382 and the element substrate 386 are arranged to face each other in the D1 direction via a frame-shaped sealing material 385. The liquid crystal layer 384 is positioned between the opposing substrate 382 and the element substrate 386 in the D1 direction and is surrounded by the sealing material 385 in a plane including the D2 and D3 directions.

[0232] A counter electrode is provided on the -D1 side surface of the opposing substrate 382, ​​which is parallel to the plane including the D2 and D3 directions. Multiple pixel electrodes corresponding to multiple pixels and a switching element are provided on the -D1 side surface of the element substrate 326, which is parallel to the plane including the D2 and D3 directions. The multiple pixel electrodes face the counter electrode in the D1 direction via the liquid crystal layer 384.

[0233] The exit-side polarizing element 177 of the optical modulation device 483 includes an anti-reflective coating 391, a phase difference plate 393, an absorption polarizing layer 394, anti-reflective coatings 395 and 397, and a phase difference plate 398. The anti-reflective coating 391, the phase difference plate 393, the absorption polarizing layer 394, and the phase difference plate 333 are arranged sequentially from the +D1 side to the -D1 side, are integrally formed with each other, constitute a part of the exit-side polarizing element 177, and are positioned between the optical modulation element 183 and the photosynthesis element 200 in the D1 direction. The anti-reflective coating 397 and the phase difference plate 398 are arranged sequentially from the +D1 side to the -D1 side, are integrally formed with each other, constitute the remainder of the exit-side polarizing element 177, and are positioned on the incident surface 210e of the cross dichroic prism 210 which forms the photosynthesis element 200.

[0234] The anti-reflective coating 391 prevents the reflection of the blue image light IB emitted from the optical modulation element 183 to the +D1 side, and directs almost all of the incident image light IB to the -D1 side. The phase difference plate 393 is provided on the emission surface of the anti-reflective coating 391 and changes the polarization state of the image light IB that passes through the anti-reflective coating 391.

[0235] The absorption polarization layer 394 is provided on the exit surface of the phase difference plate 393 and transmits image light IB with a predetermined polarization direction emitted from the phase difference plate 393, while absorbing image light IB with polarization directions other than the predetermined polarization direction emitted from the phase difference plate 393. Note that if the amount of image light IB with polarization directions other than the predetermined polarization direction emitted from the phase difference plate 393 to the -D1 side is sufficiently small, the absorption polarization layer 394 may be omitted. The anti-reflective film 395 is provided on the exit surface of the absorption polarization layer 394 and prevents reflection of the blue image light IB emitted from the optical modulation element 183 to the +D1 side, and emits almost all incident image light IB to the -D1 side.

[0236] The anti-reflective coating 397 is positioned on the -D1 side of the anti-reflective coating 395, preventing reflection of the image light IB emitted from the anti-reflective coating 395 toward the +D1 side, and directing almost all of the incident image light IB toward the -D1 side. The phase difference plate 398 changes the polarization state of the image light IB emitted from the absorption polarizing layer 332. The phase difference plate 398 functions similarly to a λ / 4 wave plate, changing the polarization state of the incident image light IB, for example, converting linearly polarized light to circularly polarized light. The phase difference plate 398 is composed of, for example, a known phase difference plate.

[0237] Figure 8 shows an example of the principal ray of the blue light LB emitted from the light-emitting element 423 of the light source 123, which is incident on the light guide element 143 from the incident end 143a and propagates directly to the exit end 143b without ever being incident on the reflective surface 143r.

[0238] The blue light LB emitted from a position PB1 on the light-emitting surface of the light-emitting element 423 toward the -D1 side is unpolarized blue light LBN, which includes S-polarized and P-polarized light. It enters the light guide element 143 from the incident end 143a, is guided toward the -D1 side by the light guide element 143, and is emitted from the exit end 143b. The blue light LBN emitted from the light guide element 143 is parallelized along the D1 direction by the parallelizing element 163, enters the incident polarizing element 173, and passes through the anti-reflective coating 371 of the incident polarizing element 173.

[0239] Blue light LBN transmitted through the anti-reflective coating 371 is incident on the phase difference plate 372 from the +D1 side and passes through the phase difference plate 372 from the +D1 side to the -D1 side. The polarization state of the blue light LBN changes as it passes through the phase difference plate 372. However, the polarization conversion by the phase difference plate 372 acts on blue light LB that can be returned to the phase difference plate 372 by the absorption polarization layer 374 and blue light LB that is returned to the phase difference plate 312 by the reflection polarization layer, etc. Of the blue light LBN emitted from the phase difference plate 372, for example, vertically polarized blue light LBT is sequentially transmitted through the absorption polarization layer 374 and the anti-reflective coating 375 and emitted from the incident polarizing element 173 to the -D1 side. Of the blue light LBN emitted from the phase difference plate 372, for example, transversely polarized blue light LBH is absorbed by the absorption polarization layer 374.

[0240] The blue light LBT emitted from the incident polarizing element 173 is converted into blue image light IB by the optical modulation element 183. The image light IB emitted from the optical modulation element 183 passes sequentially from the -D1 side to the +D1 side through the anti-reflective coating 391, phase difference plate 393, absorption polarizing layer 394, and anti-reflective coating 395 of the exit polarizing element 177. The image light IB emitted from the absorption polarizing layer 394 to the -D1 side has a polarization with a predetermined polarization direction.

[0241] The image light IB emitted from the anti-reflective coating 397 passes sequentially through the anti-reflective coating 397 and the phase difference plate 398 of the output polarizing element 177 from the -D1 side to the +D1 side. The image light IB emitted from the phase difference plate 398 to the -D1 side includes S-polarized and P-polarized light.

[0242] Furthermore, as mentioned above, in the case where a reflective polarization layer (not shown) is provided between the phase difference plate 372 and the absorption polarization layer 374 in the incident polarizing element 173 shown in Figure 8, the transversely polarized blue light LBH of the blue light LBN emitted from the phase difference plate 372 and incident on the reflective polarization layer is reflected by the reflective polarization layer, incident on the phase difference plate 372 again from the -D1 side, and is converted into circularly polarized blue light LBC by passing through the phase difference plate 372. The blue light LBC includes S-polarization and P-polarization. The blue light LBC emitted from the phase difference plate 372 to the +D1 side passes through the anti-reflective film 371 and is emitted from the incident polarizing element 173 to the +D1 side.

[0243] The blue light LBC emitted from the incident polarizing element 173 to the +D1 side passes through the parallelizing element 163, enters the light guide element 143 from the exit end 143b, is guided to the -D1 side by the light guide element 143, and is emitted from the incident end 143a. At least a portion of the blue light LBC emitted from the light guide element 143 to the +D1 side is reflected to the -D1 side at a position PB2 different from position PB1 on the light-emitting surface of the light-emitting element 423 of the light source 123. When reflected from the light-emitting surface of the light-emitting element 423, the polarization state of the blue light LBC does not change and remains circularly polarized.

[0244] The blue light LBC reflected from the light-emitting surface of the light-emitting element 423 of the light source 123 toward the -D1 side is guided toward the -D1 side by the light guide element 141 and emitted from the emission end 143b. The blue light LBC emitted from the light guide element 143 passes through the parallelizing element 163, enters the incident polarizing element 173, and passes through the anti-reflective coating 371 of the incident polarizing element 173.

[0245] Blue light LBC transmitted through the anti-reflective coating 371 is incident on the phase difference plate 372 from the +D1 side and passes through the phase difference plate 372. The polarization state of the blue light LBC changes as it passes through the phase difference plate 372 and is converted into vertically polarized blue light LBT. The blue light LBT emitted from the phase difference plate 372 and incident on the absorption polarizing layer 374 is sequentially transmitted through the anti-reflective coating 375 and emitted from the incident polarizing element 173 to the -D1 side. The direction of vibration of the blue light LBT emitted from the incident polarizing element 173 to the -D1 side is, for example, parallel to the D1 direction.

[0246] The blue light LBT emitted from the incident polarizing element 173 toward the +D1 side is converted into image light IB by the optical modulator 183. The direction of vibration of the image light IB emitted from the optical modulator 183 toward the -D1 side is, for example, parallel to the D2 direction. As described above, the direction of vibration of the image light IB emitted from the phase difference plate 398 of the exit polarizing element 177 toward the -D1 side includes, for example, multiple directions.

[0247] Image light IB with a predetermined polarization direction, emitted from the optical modulation element 183 and incident on the emission-side polarizing element 177 from the -D1 side, passes through the anti-reflective coating 391, the phase difference plate 393, the absorption polarizing layer 394, and the anti-reflective coating 395, and is converted back into image light IB with a predetermined polarization direction. Image light IB with a predetermined polarization direction, emitted from the anti-reflective coating 395 and incident on the anti-reflective coating 397 from the +D1 side, is converted, for example, into circularly polarized light by the phase difference plate 398. Image light IB emitted from the emission-side polarizing element 177 to the -D1 side is incident on the cross dichroic prism 210 of the photosynthesis element 200 from the incident surface 210e, as described above.

[0248] Figure 9 is a graph showing an example of numerical calculation results for the thickness dependence of the phase modulation amount of a single-layer quartz substrate 403 forming a phase difference plate 372 with respect to blue light LB, and the spectrum of blue light LB incident on the quartz substrate 403. In this numerical calculation, the thickness in the D1 direction of a single-layer quartz substrate 403, composed of one quartz substrate, was varied to 0.327 mm and 0.643 mm. The thickness in the D1 direction of a two-layer bonded quartz substrate 403, composed of two quartz substrates, was set to 0.600 mm. The angle between the crystal axis of the single-layer quartz substrate 403 and the transmission axis of a reflective polarizing plate (not shown) was set to 45°. For the two-layer bonded quartz substrate 403, it was assumed that the crystal axis of the +D1 side quartz substrate was at an angle of 45° with respect to the transmission axis of a reflective polarizing layer (not shown), and the crystal axis of the -D1 side quartz substrate was at an angle of 135° with respect to the transmission axis of a reflective polarizing layer (not shown).

[0249] As shown in Figure 9, the full width at half maximum (FWHM) of the phase modulation profile of a single-layer quartz substrate 403 is considerably narrower than that of a two-layer quartz substrate 403, regardless of whether the thickness of the quartz substrate 403 is 0.327 mm or 0.643 mm, and is shorter than the FWHM of the blue light LB spectrum, which is about 20 nm.

[0250] When the thickness of the quartz substrate 403 is 0.327 mm and 0.643 mm, if the quartz substrate 403 is made of a single sheet, it is possible to change the polarization state of some of the incident blue light LB, but it is difficult to change the polarization state of the main blue light LB in the wavelength band that satisfies at least half value to the maximum value of the spectral profile of the blue light LB using the quartz substrate 403 of the phase difference plate 372. By making the quartz substrate 403 a single sheet, the cost of the quartz substrate 403 and the projector 350 can be reduced.

[0251] If the thickness of the quartz substrate 401 is 0.600 mm, then if the quartz substrate 403 is constructed by bonding two sheets together as described above, the polarization state of the blue light LB across the entire wavelength band that satisfies the minimum value of the incident blue light LB's light intensity, i.e., between zero and the maximum value, can be changed by the quartz substrate 403 of the phase difference plate 372. This improves the polarization conversion capability of the quartz substrate 403 compared to when the quartz substrate 403 is constructed as a single sheet.

[0252] The angle between the crystal axis of the quartz substrate 403 and the transmission axis of the reflective polarizing layer (not shown), the thickness of the quartz substrate 403 in the D1 direction, and whether the quartz substrate 403 is made of a single sheet or two sheets bonded together can be determined, as in the example above, based on the wavelength dependence of the phase modulation amount of the quartz substrate 403 considering each configuration, and the numerical calculation results of the spectrum of the blue light LB emitted from the light source 123 and incident on the quartz substrate 403. The phase difference plate 372 may have two or more quartz substrates, and two or more quartz substrates may be laminated in the D1 direction.

[0253] The optical module 310 of this embodiment, as described above, comprises a light source (first light source) 121, a light guide element (first light guide element) 141, a parallelizing element (first parallelizing element) 161, and a light modulator (first light modulator) 481. The light source 121 emits red light (first light) LR in a wavelength band including the red wavelength band (first wavelength band). The light guide element 141 has an incident end (first incident end) 141a into which the red light LR emitted from the light source 121 is incident, and an exit end (first exit end) 141b that emits the red light LR, and homogenizes the in-plane illuminance (in-plane illuminance) including the D2 and D3 directions of the red light LR. The parallelizing element 161 parallelizes the red light LR emitted from the light guide element 141. The light modulator 181 modulates the red light LR emitted from the parallelizing element 161 based on image information. The incident polarizing element 171 of the optical modulator 481 includes a phase difference plate (first polarization conversion section) 312 and a reflective polarizing layer (first polarization separation section) 313. The phase difference plate 312 changes the polarization state of the red light LR emitted from the parallelizing element 161 and incident on the incident polarizing element 171. The reflective polarizing layer 313 transmits the vertically polarized red light (at least a portion of the first polarization component) LRT of the red light LR passing through the phase difference plate 312 and reflects the transversely polarized red light (another portion) LRH of the red light LR passing through the phase difference plate 312. In the optical module 310 of this embodiment, the phase difference plate 312 changes the polarization state of the red light (another portion of the first light) LRH reflected from the reflective polarizing layer 313.

[0254] In the optical module 310 of this embodiment, the light-emitting element 421 of the light source 121 is an LED that emits color light containing all polarization components, rather than color light containing only a specific polarization component, such as unpolarized light including random polarization. Of the red light LR emitted from the light source 121, only the color light of a specific polarization component corresponding to the first polarization component, i.e., longitudinally polarized red light LRT, is converted into red image light IR by the optical modulation element 181 and used to form an image with the image light emitted from the optical module 310.

[0255] Figure 10 is a schematic graph showing the polarization ratio of red light LR of each order incident on the reflective polarization layer 313 from the -D1 side in the incident polarizing element 171 of the optical modulator 481 of the optical module 310 of this embodiment. As shown in Figure 10, the first-order red light LR that is initially emitted from the position PR1 of the light-emitting surface of the light-emitting element 421 of the light source 121 and incident on the reflective polarization layer 313 from the -D1 side contains approximately 50% P-polarization corresponding to transverse polarization and approximately 50% S-polarization corresponding to longitudinal polarization.

[0256] The polarization state of the second-order red light LR, which is reflected by the reflective polarization layer 313 and emitted from the position PR2 of the light-emitting surface PR2 of the light-emitting element 421 of the light source 121 towards the +D1 side and incident on the reflective polarization layer 313 from the -D1 side, is changed by the phase difference plate 312. Therefore, the proportion of second-order longitudinally polarized red light LRT, i.e., S polarization, and the proportion of second-order transversely polarized red light LRH, i.e., P polarization, is approximately 10% to 20%. Because the phase difference plate 312 is positioned on the -D1 side of the reflective polarization layer 313, the polarization state of the red light LR that returns from the +D1 side to the light-emitting element 421 of the light source 121 and is reflected back to the -D1 side changes. As the order of the red light LR increases, the proportion of red light LRT and LRH decreases, and higher-order red light LRH contributes to the generation of image light IR.

[0257] Figure 11 is a schematic graph showing the polarization ratios of red light of each order incident on a reflective or absorptive polarizer in the incident polarizing element of the optical modulator of a conventional optical module without a phase difference plate 312. As shown in Figure 11, in conventional optical modules, since a configuration equivalent to the phase difference plate 312 is not provided, the proportion of S-polarized light transmitted through the polarizer in the second-order red light is approximately 0%, and the proportion of P-polarized light shielded by the polarizer in the second-order red light is approximately 25%. In conventional optical modules, the P-polarized light of higher-order red light remains between the light source device and the polarizer in the incident polarizing element of the optical modulator, or becomes stray light inside the projector's casing, and does not contribute to the generation of image light (IR). As a result, conventional optical modules without a phase difference plate 312 suffer from reduced light utilization efficiency.

[0258] According to the optical module 310 of this embodiment, the phase difference plate 312 is positioned on the -D1 side of the reflective polarization layer 313, and the polarization conversion of the red light LR is promoted by the phase difference plate 312. As a result, at least both S-polarized and P-polarized color light of the red light LR emitted from the light source 121 is used to form the image, and the decrease in light utilization efficiency can be suppressed compared to conventional optical modules.

[0259] In addition, in the optical module 310 of this embodiment, if the incident polarizing element 173 of the optical modulator 483 has a reflective polarizing layer (not shown), the polarization ratio of the blue light LB of each order changes in the same way as the polarization ratio of the red light LR of each order illustrated in Figure 10, and the utilization efficiency of the blue light LB increases.

[0260] The optical module 310 of this embodiment further comprises a light source (second light source) 123, a light source (third light source) 122, a light guide element (second light guide element) 143, a light guide element (third light guide element) 142, a parallelizing element (second parallelizing element) 163, a parallelizing element (third parallelizing element) 162, a light modulator (second light modulator) 483, a light modulator (third light modulator) 482, and a photosynthesis element 200. The light source 123 emits blue light (second light) LB in a wavelength band that includes a blue wavelength band (second wavelength band) different from the red wavelength band. The light source 122 emits green light (third light) LG in a wavelength band that includes a green wavelength band (third wavelength band) different from the red wavelength band and the blue wavelength band. The light guide element 142 has an incident end (third incident end) 142a into which the green light LG emitted from the light source 122 is incident, and an exit end (third exit end) 142b from which the green light LG is emitted, and it equalizes the in-plane illuminance (in-plane illumination) including the D1 and D3 directions of the green light LG. The light guide element 143 has an incident end (second incident end) 143a into which the blue light LB emitted from the light source 123 is incident, and an exit end (second exit end) 143b from which the blue light LB is emitted, and it equalizes the in-plane illuminance (in-plane illumination) including the D2 and D3 directions of the blue light LB. The parallelizing element 162 parallelizes the green light LG emitted from the light guide element 142. The parallelizing element 163 parallelizes the blue light LB emitted from the light guide element 143. The light modulator 182 modulates the green light LG emitted from the light guide element 142 based on image information. The light modulator 183 modulates the blue light LB emitted from the light guide element 143 based on image information. The photosynthesis element 200 combines and emits the image light (first light) IR emitted from the light modulator 181, the image light (second light) IB emitted from the light modulator 183, and the image light (third light) IG emitted from the light modulator 182.

[0261] According to the optical module 310 of this embodiment, due to its three-chip configuration, it is possible to form a bright color image light generated by, for example, red, blue, and green image light.

[0262] In the optical module 310 of this embodiment, the phase difference plate 312 is made of a quartz substrate 401.

[0263] According to the optical module 310 of this embodiment, the first polarization conversion unit can be easily realized at low cost, and the heat dissipation of the incident polarizing element 171 can be improved.

[0264] In the optical module 310 of this embodiment, the quartz substrate 401 has a crystal axis J2, and the reflective polarizing layer 313 has a transmission axis J1 for transmitting red light LRT. When viewed along the optical axis AXR of the red light LR incident on the incident polarizing element 171 of the optical modulator 481, the angle θ1 between the crystal axis J2 and the transmission axis J1 is greater than 0° and less than 90°.

[0265] According to the optical module 310 of this embodiment, the crystal axis J2 is offset from the transmission axis J1 in the circumferential direction centered on the optical axis AXR, and the angle θ1 is appropriately set to achieve the desired polarization conversion characteristics in the phase difference plate 312.

[0266] In the optical module 310 of this embodiment, the angle θ1 is 45°, so the thickness of the quartz substrate 401 can be appropriately set, and the desired polarization conversion characteristics in the phase difference plate 312 can be easily achieved.

[0267] In the optical module 310 of this embodiment, the first light is red light LR.

[0268] In the optical module 310 of this embodiment, even if the amount of red light LR emitted from the light-emitting element 421 of the light source 121 is less than the desired amount, or if it is less than the amount of green light LG emitted from the light-emitting element 422 of the light source 122 and the amount of blue light LB emitted from the light-emitting element 423 of the light source 123, the utilization efficiency of red light LR can be increased. As a result, the color balance of the color light and image light IM emitted from the optical module 310 of this embodiment can also be improved.

[0269] In the optical module 310 of this embodiment, the thickness of the crystal substrate 401 is 0.250 mm to 0.650 mm.

[0270] The optical module 310 of this embodiment can effectively change the polarization state of most of the red light LR incident on the quartz substrate 401.

[0271] In the optical module 310 of this embodiment, the quartz substrate 401 is composed of a first quartz substrate 411 and a second quartz substrate 412. The first quartz substrate has a first crystal axis J11. The second crystal axis J12 has a second crystal axis J12. The reflective polarizing layer 313 has a transmission axis J1. When viewed along the optical axis AXR of the red light LR incident on the incident polarizing element 171 of the optical modulator 481, the angle θ11 between the first crystal axis J11 and the transmission axis J1 is 15°, and the angle θ12 between the second crystal axis J12 and the transmission axis J1 is 75°.

[0272] In the optical module 310 of this embodiment, the amount of phase modulation in the quartz substrate 401 is increased, and a relatively long wavelength band with a high amount of phase modulation is secured, allowing the polarization state of most of the red light LR incident on the quartz substrate 401 to be changed effectively and efficiently.

[0273] In the optical module 310 of this embodiment, the thickness of the first crystal substrate 411 is 0.300 mm to 0.400 mm, and the thickness of the second crystal substrate 412 is 0.100 mm to 0.200 mm.

[0274] According to the optical module 310 of this embodiment, the polarization conversion characteristics of the quartz substrate 401 can be easily adjusted, and the polarization state of most of the red light LR incident on the quartz substrate 401 can be efficiently changed.

[0275] In the optical module 310 of this embodiment, the incident surface on the -D1 side of the red light LR in the reflective polarization layer 313 is in contact with the exit surface on the +D1 side of the red light LR in the phase difference plate 312, and the phase difference plate 312 and the reflective polarization layer 313 are configured as an integral part of each other.

[0276] In the optical module 310 of this embodiment, the polarization conversion efficiency of the incident polarizing element 171 can be increased, and the incident polarizing element 171 can be miniaturized in the D1 direction.

[0277] In the optical module 310 of this embodiment, the cross-sectional shape of the light guide element 141 perpendicular to the optical axis and the D1 direction is rectangular.

[0278] In the optical module 310 of this embodiment, the light guide element 141 can easily generate red light LR having a rectangular shape and uniform illuminance in a plane perpendicular to the optical axis of the color light. According to the optical module 310 of this embodiment, rectangular color light matching the shape of the modulation surface of the light modulation element 181 can be easily generated.

[0279] In the optical module 310 of this embodiment, the cross-sectional area of ​​the exit end 141b of the light guide element 141 is larger than the cross-sectional area of ​​the incident end 141a of the light guide element 141.

[0280] In the optical module 310 of this embodiment, the illuminance distribution of the red light LR is made uniform from the time it enters the light guide element 141a through the incident end 141a until it is emitted from the exit end 141b, thereby expanding the irradiation area of ​​the red light LR. According to the optical module 310 of this embodiment, the illuminance distribution of the red light LR emitted from the light source 121 can be made uniform on a plane perpendicular to the optical axis, and the size of the plane perpendicular to the optical axis of the red light LR, i.e., the irradiation area, can be easily expanded to match the modulation plane of the optical modulation element 183.

[0281] In the optical module 310 of this embodiment, when viewed along the optical axis of the red light LR incident on the optical modulator 481, the modulation surface of the optical modulator 181 is rectangular, and the incident surfaces of the phase difference plate 312 and the reflective polarization layer 313 are rectangular.

[0282] In the optical module 310 of this embodiment, since the shapes of the incident surfaces of the phase difference plate 312 and the reflective polarization layer 313 are rectangular, similar to the modulation surface of the optical modulation element 181, red light LR having a beam shape that matches the modulation surface of the optical modulation element 181 can be easily emitted from the reflective polarization layer 313 of the incident polarization element 171, and the red light LR emitted from the incident polarization element 171 is incident on the optical modulation element 181, thereby suppressing a decrease in the utilization efficiency of the red light LR.

[0283] The projector 350 of the present embodiment includes the above-described optical module 310 of the present embodiment and a projection optical system 390 that projects image light (light) IM emitted from the optical module 310. The light source 121 has a light-emitting element (first light-emitting element) 421 that emits red light LR. The light source 123 has a light-emitting element (second light-emitting element) 423 that emits blue light LB. The light-emitting element 422 of the light source 122 has an LED body (third light-emitting element) 124 and a phosphor (wavelength conversion element) 125. The LED body 124 emits, for example, blue light (fourth light) as excitation light. The phosphor 125 converts the blue light emitted from the LED body 124 into green light LG.

[0284] In the projector 350 of the present embodiment, the incident-side polarizing element 171 of the optical modulation device 481 that modulates, for example, red light LR as the first light from the light source 121 having no phosphor has a retardation plate 312 and a reflective polarizing layer 313. The incident-side polarizing element 173 of the optical modulation device 483 that modulates, for example, blue light LB as the second light from the highly reliable light source 123 having no phosphor may not have a retardation plate and a reflective polarizing layer. The incident-side polarizing element 172 of the optical modulation device 482 that modulates green light LG from the light source 122 having the phosphor 125 may not have a retardation plate and a reflective polarizing layer. In the projector 350 of the present embodiment, it is possible to improve the utilization efficiency of color light that is relatively likely to have insufficient light quantity, such as the light source 121 that emits at least red light LR.

[0285] Note that in the projector 350 of the present embodiment, the incident-side polarizing element 172 of the optical modulation device 482 has a retardation plate 342 and a reflective polarizing layer 343, and the green light LG reflected to the -D2 side by the reflective polarizing layer 343 contributes to the re-excitation of the phosphor 125. In the projector 350 of the present embodiment, although it may not have an effect of improving the utilization efficiency of red light LR, it is possible to improve the utilization efficiency of green light LG.

[0286] In the projector 350 of the present embodiment, the optical modulation device 483 may include a retardation plate 372 and a reflection polarizing layer (not shown). The retardation plate 372 changes the polarization state of the blue light LB emitted from the parallelizing element 163. The reflection polarizing layer (not shown) transmits the vertically polarized blue light (at least a part of the second polarization component) LBT among the blue light LB that passes through the retardation plate 372, and reflects the horizontally polarized blue light (another part) LBH among the blue light LB that passes through the retardation plate 372. In the projector 350 of the present embodiment, the retardation plate 372 changes the polarization state of the blue light (another part of the second light) LBH reflected from the reflection polarizing layer (not shown).

[0287] In the projector 350 of the present embodiment, similar to the light emitting element 421 of the light source 121, as the light emitting element 423 of the light source 123, for example, an LED that emits colored light including all polarization components instead of colored light with only specific polarization components such as non-polarized light including random polarization is adopted. Only the colored light of the specific polarization component corresponding to the second polarization component among the blue light LB emitted from the light source 123, that is, only the vertically polarized blue light LBT is converted into blue image light IB by the optical modulation element 183 and is used for forming an image by the image light IM emitted from the optical module 310. According to the projector 350 of the present embodiment, in addition to the utilization efficiency of the red light LR, the utilization efficiency of the blue light LB can be increased.

[0288] In the projector 350 of the present embodiment, the first light is the red light LR, and the incident-side polarizing element 171 of the optical modulation device 481 has a retardation plate 312 and a reflection polarizing layer 313. The incident-side polarizing element 173 of the optical modulation device 483 does not have a polarization conversion unit, a retardation plate, etc. that change the polarization state of the blue light LB emitted from the parallelizing element 163. The incident-side polarizing element 172 of the optical modulation device 482 does not have a polarization conversion unit, a retardation plate, etc. that change the polarization state of the green light LG emitted from the parallelizing element 162.

[0289] In the projector 350 of this embodiment, if only the incident polarizing element 171 of the optical modulator 481 has a phase difference plate 312 among the incident polarizing elements 171, 172, and 173 of the optical modulators 481, 482, and 483, the utilization efficiency of color light, which tends to be relatively insufficient in terms of light intensity, such as the light source 121 that emits red light LR, can be reliably increased.

[0290] In the projector 350 of this embodiment, the quartz substrate 403 is composed of a quartz substrate (third quartz substrate) positioned on the -D1 side in the bonding of two substrates and a quartz substrate (fourth quartz substrate) positioned on the +D1 side in the bonding of two substrates. The third quartz substrate has a third crystal axis. The fourth quartz substrate has a fourth crystal axis. A reflective polarizing layer (not shown) has a transmission axis. When viewed along the optical axis of the blue light LB incident on the incident polarizing element 173 of the optical modulator 483, the angle between the third crystal axis and the transmission axis of the reflective polarizing layer (not shown) is 45°, and the angle between the fourth crystal axis and the transmission axis of the reflective polarizing layer (not shown) is 135°.

[0291] In the projector 350 of this embodiment, the amount of phase modulation in the quartz substrate 403 is increased, and a relatively long wavelength band with high phase modulation is secured, allowing the polarization state of most of the blue light LB incident on the quartz substrate 403 to be changed effectively and efficiently.

[0292] Although preferred embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the invention as described in the claims.

[0293] For example, similar to the green light emission unit 102, the red light emission unit 101 and the blue light emission unit 103 may also include phosphors that are excited by light from the LED body to emit red light LR and blue light LB, respectively, in the LEDs constituting the light sources 121 and 123. Alternatively, in the green light emission unit 102, the light-emitting element 422 of the light source 122 may consist only of an LED body that emits green light LG without a phosphor. In the optical module of this embodiment, it is desirable that the optical modulator corresponding to the light source of colored light having a light-emitting element without a phosphor is equipped with an incident polarizing element similar to the incident polarizing element 171 having a phase difference plate 312 and a reflective polarizing layer 313, similar to the optical modulator 481 of the optical module 310.

[0294] For example, each of the light guide elements 141, 142, and 143 may be a reflector made of a transparent material having a higher refractive index than air, such as optical glass or quartz, or it may be formed as a solid member. If the light guide elements 141, 142, and 143 are solid members made of the aforementioned transparent material, the reflective surfaces 141r, 142r, and 143r are composed of the sides facing outward from the solid member. The majority of the red light LR, green light LG, and blue light LB incident on the light guide elements 141, 142, and 143 from the incident ends 141a, 142a, and 143a are totally reflected by the reflective surfaces 141r, 142r, and 143r toward the exit ends 141b, 142b, and 143b.

[0295] For example, the exit-side polarizing element 175 of the optical modulator 481 may be configured without a phase difference plate 333. Also, the exit-side polarizing element 177 of the optical modulator 483 may be configured without either or both of the phase difference plates 393 and 398.

[0296] [Summary of this disclosure] A summary of this disclosure is provided below. (Note 1) An optical module comprising: a first light source that emits first light in a first wavelength band; a first light guide element having a first incident end into which the first light emitted from the first light source is incident and a first exit end that emits the first light, and which makes the in-plane illuminance of the first light uniform; a first parallelizing element that parallelizes the first light emitted from the first light guide element; and a first light modulation device that modulates the first light emitted from the first parallelizing element based on image information, wherein the first light modulation device has a first polarization conversion unit that changes the polarization state of the first light emitted from the first parallelizing element, and a first polarization separation unit that transmits at least a portion of the first polarization component of the first light passing through the first polarization conversion unit and reflects the other portion, and the first polarization conversion unit changes the polarization state of the other portion of the first light reflected from the first polarization separation unit.

[0297] With the configuration described in Appendix 1, the first polarization conversion unit is positioned on the incident side of the first light than the first polarization separation unit, and the polarization conversion of the first light is promoted by the first polarization conversion unit. As a result, at least both S-polarized and P-polarized colored light of the first light emitted from the first light source can be used to form an image, and the decrease in light utilization efficiency in the optical module can be suppressed compared to conventional methods.

[0298] (Note 2) 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 and second wavelength bands; 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 into which the second light is emitted, and which equalizes the in-plane illuminance of 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 into which the third light is emitted, and which equalizes the in-plane illuminance of the third light; and before the light emitted from the second light guide element An optical module as described in Appendix 1, comprising: a second parallelizing element for parallelizing the second light; a third parallelizing element for parallelizing the third light emitted from the third light guide element; a second light modulator for modulating the second light emitted from the second parallelizing element based on image information; a third light modulator for modulating the third light emitted from the third parallelizing element based on image information; and a photosynthesis element for synthesizing and emitting the first light emitted from the first light modulator, the second light emitted from the second light modulator, and the third light emitted from the third light modulator.

[0299] The configuration described in Appendix 2 constitutes a three-chip optical module, which can, for example, form bright color image light generated by red, blue, and green image light.

[0300] (Note 3) The optical module according to Note 1 or Note 2, wherein the first polarization conversion unit is made of a quartz substrate.

[0301] The configuration described in Appendix 3 allows for the easy and low-cost implementation of the first polarization conversion unit and improves heat dissipation in the incident polarizing element of the first optical modulator.

[0302] (Note 4) An optical module according to any of Notes 1 to 3, wherein the quartz substrate has a crystal axis, the first polarization separation unit has a transmission axis, and when viewed along the optical axis of the first light incident on the first light modulator, the angle between the crystal axis and the transmission axis is greater than 0° and less than 90°.

[0303] With the configuration of Supplementary Note 4, the crystal axis is shifted from the transmission axis in the circumferential direction centered on the optical axis of the first light incident on the incident-side polarizing element of the first optical modulation device, and the angle formed by the crystal axis and the transmission axis is appropriately set, so that the desired polarization conversion characteristics in the first polarization conversion unit can be realized.

[0304] (Supplementary Note 5) The optical module of Supplementary Note 4, wherein the angle is 45°.

[0305] With the configuration of Supplementary Note 5, the thickness of the crystal substrate of the first polarization conversion unit is appropriately set, so that the desired polarization conversion characteristics in the first polarization conversion unit can be easily realized.

[0306] (Supplementary Note 6) The optical module of Supplementary Note 5, wherein the first light is red light.

[0307] With the configuration of Supplementary Note 6, for example, even when the light quantity of the red light emitted from the first light source is less than that of other color lights, the utilization efficiency of the red light can be increased, and the color balance of the color light and the image light emitted from the optical module can be improved.

[0308] (Supplementary Note 7) The optical module of Supplementary Note 5 or Supplementary Note 6, wherein the thickness of the crystal substrate is 0.250 mm to 0.650 mm.

[0309] With the configuration of Supplementary Note 7, the polarization state of most of the first light incident on the crystal substrate of the first polarization conversion unit can be favorably changed and adjusted.

[0310] (Supplementary Note 8) The optical module of Supplementary Note 3, wherein the crystal substrate is composed of a first crystal substrate and a second crystal substrate integrated with each other, the first crystal substrate has a first crystal axis, the second crystal substrate has a second crystal axis, the first polarization separation unit has a transmission axis, and when viewed along the optical axis of the first light incident on the first optical modulation device, the angle formed by the first crystal axis and the transmission axis is 15°, and the angle formed by the second crystal axis and the transmission axis is 75°.

[0311] The configuration described in Appendix 8 increases the amount of phase modulation in the quartz substrate of the first polarization conversion unit, secures a relatively long wavelength band with high phase modulation, and allows for efficient and effective modification of the polarization state of most of the first light incident on the quartz substrate.

[0312] (Note 9) The optical module of Note 3, wherein the thickness of the first quartz substrate is 0.300 mm to 0.400 mm, and the thickness of the second quartz substrate is 0.100 mm to 0.200 mm.

[0313] The configuration described in Appendix 9 allows for easy adjustment of the polarization conversion characteristics of the quartz substrate in the first polarization conversion unit, and efficiently changes the polarization state of most of the first light incident on the quartz substrate.

[0314] (Note 10) An optical module according to any of Notes 1 to 9, wherein the incident surface of the first light in the first polarization separation unit is in contact with the emission surface of the first light in the first polarization conversion unit, and the first polarization separation unit and the first polarization conversion unit are configured as an integral part of each other.

[0315] The configuration described in Appendix 10 makes it possible to increase the polarization conversion efficiency of the incident polarizing element of the first optical modulator and to miniaturize the incident polarizing element of the first optical modulator.

[0316] (Note 11) The cross-sectional shape of the first light guide element is rectangular, any of the optical modules specified in Notes 1 to 10.

[0317] With the configuration described in Appendix 11, the first light guide element can easily generate a first light having a rectangular shape and uniform illuminance in a plane perpendicular to the optical axis of the color light, and can easily generate a rectangular color light that matches the shape of the modulation surface of the first light modulation element.

[0318] (Note 12) Any optical module specified in Notes 1 to 10, wherein the cross-sectional area of ​​the first exit end is greater than the cross-sectional area of ​​the first entrance end.

[0319] With the configuration described in Appendix 12, the illuminance distribution of the first light can be made uniform on a plane perpendicular to the optical axis, and the size of the plane perpendicular to the optical axis of the first light, i.e., the irradiation area, can be easily enlarged to match the modulation plane of the optical modulation element of the first light modulator.

[0320] (Note 13) The optical module of Note 11, wherein, when viewed along the optical axis of the first light incident on the first optical modulator, the shape of the modulation plane is rectangular, and the shape of the incident plane of the first polarization separator is rectangular.

[0321] The configuration described in Appendix 13 allows for the easy emission of first light having a beam shape matched to the modulation plane of the optical modulation element from the first polarization separation section of the incident polarizing element of the first optical modulation device, thereby reducing the decrease in the utilization efficiency of the first light.

[0322] (Note 14) A projector comprising an optical module as described in any of Notes 2 to 13, and a projection optical system for projecting light emitted from the optical module, wherein the first light source has a first light-emitting element that emits the first light, the second light source has a second light-emitting element that emits the second light, and the third light source has a third light-emitting element that emits the fourth light and a wavelength conversion element that converts the fourth light emitted from the third light-emitting element into the third light.

[0323] The configuration described in Appendix 14 makes it possible to improve the utilization efficiency of colored light, which tends to be relatively insufficient in terms of light intensity, such as the first light source that emits first light.

[0324] (Note 15) The projector according to Note 14, wherein the second optical modulation device includes a second polarization conversion unit that changes the polarization state of the second light emitted from the second parallelizing element, and a second polarization separation unit that transmits at least a portion of the second polarization component of the second light passing through the second polarization conversion unit and reflects the other portion, and the second polarization conversion unit changes the polarization state of the other portion of the second light reflected from the second polarization separation unit.

[0325] With the configuration described in Appendix 15, the second polarization component of the second light is converted into image light by the second light modulator and used to form an image with the image light emitted from the optical module. Therefore, in addition to the utilization efficiency of the first light, the utilization efficiency of the second light can be increased.

[0326] (Note 16) The projector according to Note 14, wherein the first light is red light, the first light modulator has the first polarization conversion unit, the second light modulator does not have a polarization conversion unit for changing the polarization state of the second light emitted from the second parallelizing element, and the third light modulator does not have a polarization conversion unit for changing the polarization state of the third light emitted from the third parallelizing element.

[0327] The configuration described in Appendix 16 makes it possible to reliably improve the utilization efficiency of colored light, which tends to be relatively insufficient in terms of light intensity, such as the first light source that emits the first light.

[0328] (Note 17) The projector as described in Note 15, wherein the second polarization conversion unit is made of a quartz substrate, the quartz substrate is made of a third quartz substrate and a fourth quartz substrate, the third quartz substrate has a third crystal axis, the fourth quartz substrate has a fourth crystal axis, the second polarization conversion unit has a transmission axis, and when viewed along the optical axis of the second light incident on the second light modulator, the angle between the third crystal axis and the transmission axis is 45°, and the angle between the fourth crystal axis and the transmission axis is 135°.

[0329] The configuration described in Appendix 17 increases the amount of phase modulation in the quartz substrate of the second polarization conversion unit, secures a relatively long wavelength band with high phase modulation, and allows for efficient and effective modification of the polarization state of most of the second light incident on the quartz substrate of the second polarization conversion unit. [Explanation of Symbols]

[0330] 121...Light source (first light source), 123...Light source (second light source), 141...Light guide element (first light guide element), 143...Light guide element (second light guide element), 312...Phase difference plate (first polarization conversion unit), 313...Reflective polarization layer (first polarization separation unit), 481...Optical modulator (first optical modulator), 483...Optical modulator (second optical modulator), 200...Photosynthesis element, 310...Optical module, 350...Projector, 390...Projection optical system.

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, and which makes the in-plane illuminance of the first light uniform, A first parallelizing element that parallelizes the first light emitted from the first light guide element, A first optical modulation device that modulates the first light emitted from the first parallelizing element based on image information, Equipped with, The first optical modulation device is A first polarization conversion unit that changes the polarization state of the first light emitted from the first parallelizing element, A first polarization separation unit that transmits at least a portion of the first polarization component of the first light passing through the first polarization conversion unit and reflects the other portion, It has, The first polarization conversion unit changes the polarization state of the other portion of the first light reflected from the first polarization separation unit. Optical module.

2. 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, and which makes the in-plane illuminance of the second light uniform, 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 for emitting the third light, and which makes the in-plane illuminance of the third light uniform, A second parallelizing element that parallelizes the second light emitted from the second light guide element, A third parallelizing element that parallelizes the third light emitted from the third light guide element, A second optical modulation device that modulates the second light emitted from the second parallelizing element based on image information, A third optical modulator that modulates the third light emitted from the third parallelizing element based on image information, A photosynthetic element that combines and emits the first light emitted from the first light modulator, the second light emitted from the second light modulator, and the third light emitted from the third light modulator, Equipped with, The optical module according to claim 1.

3. The first polarization conversion unit is made of a quartz substrate. The optical module according to claim 1 or claim 2.

4. The quartz substrate has a crystal axis, The first polarization separation unit has a transmission axis, When viewed along the optical axis of the first light incident on the first light modulator, the angle between the crystal axis and the transmission axis is greater than 0° and less than 90°. The optical module according to claim 3.

5. The aforementioned angle is 45°. The optical module according to claim 4.

6. The first light is red light. The optical module according to claim 5.

7. The thickness of the aforementioned quartz substrate is 0.250 mm to 0.650 mm. The optical module according to claim 5.

8. The aforementioned crystal substrate is composed of a first crystal substrate and a second crystal substrate that are integrated with each other. The first quartz substrate has a first crystal axis, The second quartz substrate has a second crystal axis, The first polarization separation unit has a transmission axis, When viewed along the optical axis of the first light incident on the first light modulator, the angle between the first crystal axis and the transmission axis is 15°, and the angle between the second crystal axis and the transmission axis is 75°. The optical module according to claim 3.

9. The thickness of the first quartz substrate is 0.300 mm to 0.400 mm. The thickness of the second quartz substrate is 0.100 mm to 0.200 mm. The optical module according to claim 8.

10. The incident surface of the first light in the first polarization separation unit is in contact with the emission surface of the first light in the first polarization conversion unit, and the first polarization separation unit and the first polarization conversion unit are configured as an integral part of each other. The optical module according to claim 1 or claim 2.

11. The cross-sectional shape of the first light guide element is rectangular. The optical module according to claim 1 or claim 2.

12. The cross-sectional area of ​​the first injection end is larger than the cross-sectional area of ​​the first injection end. The optical module according to claim 1 or claim 2.

13. When viewed along the optical axis of the first light incident on the first optical modulator, the shape of the modulation plane is rectangular, and the shape of the incident plane of the first polarization separation unit is rectangular. The optical module according to claim 11.

14. The optical module according to claim 2, A projection optical system that projects light emitted from the optical module, Equipped with, The first light source has a first light-emitting element that emits the first light, The second light source has a second light-emitting element that emits the second light, The third light source is, A third light-emitting element that emits a fourth light, A wavelength conversion element that converts the fourth light emitted from the third light-emitting element into the third light, Having, projector.

15. The second optical modulation device is A second polarization conversion unit that changes the polarization state of the second light emitted from the second parallelizing element, A second polarization separation unit that transmits at least a portion of the second polarization component of the second light passing through the second polarization conversion unit and reflects the other portion, It has, The second polarization conversion unit changes the polarization state of the other portion of the second light reflected from the second polarization separation unit. The projector according to claim 14.

16. The first light is red light, The first optical modulation device has the first polarization conversion unit, The second optical modulation device does not have a polarization conversion unit that changes the polarization state of the second light emitted from the second parallelizing element, The third optical modulation device does not have a polarization conversion unit that changes the polarization state of the third light emitted from the third parallelizing element. The projector according to claim 14.

17. The second polarization conversion unit is composed of a quartz substrate. The aforementioned crystal substrate is composed of a third crystal substrate and a fourth crystal substrate. The third quartz substrate has a third crystal axis, The fourth quartz substrate has a fourth crystal axis, The second polarization conversion unit has a transmission axis, When viewed along the optical axis of the second light incident on the second light modulator, the angle between the third crystal axis and the transmission axis is 45°, and the angle between the fourth crystal axis and the transmission axis is 135°. The projector according to claim 15.

Images