Optical modules and projectors

Abstract

This device suppresses uneven illumination and color in projected images from image display devices such as projectors. [Solution] The optical module of the embodiment is applied to an image display device and comprises a first light source, a second light source, a third light source, a first light guide element, a second light guide element, a third light guide element, a first parallelizing element, a second parallelizing element, a third parallelizing element, a first light modulation element, a second light modulation element, a third light modulation element, and a photosynthesis element. The photosynthesis element has a first reflective film that transmits first light and reflects second light. The beam width of the first light emitted from the first light modulation element expands as it moves from the incident side of the first light to the exit side of the first light into the photosynthesis element. The thickness of the first reflective film changes according to the incident angle of the first light.

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. Projectors are classified into, for example, single-panel type and three-panel type according to the number of light sources and light modulation elements.

[0003] <00利用光学系の光軸に対して傾斜した状態で配置される。 For example, Patent Document 1 discloses a projector in which a plurality of light emitting diodes (LEDs) are used 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 is then overlapped on the same path in the same direction, modulated into image light by a light modulation element, and 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 the plurality of blocks enters a cross dichroic prism for synthesizing the lights from the 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, if a light source that emits colored light with a wider wavelength band than monochromatic light emitted from a laser, such as an LED, is used, some of the colored light incident on the cross dichroic prism may be emitted outside the optical path where it should be emitted due to the incident angle dependence of the transmittance in the dichroic mirror of the cross dichroic prism and the wavelength dependence corresponding to the incident angle dependence, potentially causing uneven illumination and color in the projected image. Therefore, there has been a need for an optical module that can suppress the occurrence of uneven illumination and color in the projected image when applied to image display devices such as projectors. [Means for solving the problem]

[0006] An optical module according to one aspect of the present invention includes: a first light source that emits first light in a first wavelength band; 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 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 into which the first light is emitted, and which equalizes the in-plane illuminance of the first light; 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; and 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. The device comprises a light guide element, a first parallelizing element that parallelizes a first light emitted from a first light guide element, a second parallelizing element that parallelizes a second light emitted from a second light guide element, a third parallelizing element that parallelizes a third light emitted from a third light guide element, a first light modulation element that modulates the first light emitted from the first parallelizing element based on image information, a second light modulation element that modulates the second light emitted from the second parallelizing element based on image information, a third light modulation element that modulates the third light emitted from the third parallelizing element based on image information, and a photosynthesis element that synthesizes and emits the first light emitted from the first light modulation element, the second light emitted from the second light modulation element, and the third light emitted from the third light modulation element. The photosynthesis element has a first reflective film that transmits the first light and reflects the second light. The beam width of the first light emitted from the first light modulation element expands as it moves from the incident side of the first light to the exit side of the first light into the photosynthetic element. The thickness of the first reflective film changes according to the incident angle of the first light. [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 main components of the projector. [Figure 3] This graph shows an example of the emission spectrum of the light source emitting green light from the projector shown in Figure 1. [Figure 4]This graph shows an example of the wavelength dependence of the transmittance of the reflective film of the color synthesis element in the projector shown in Figure 1. [Figure 5] This is a schematic diagram of the main parts of a modified version of the projector shown in Figure 1. [Figure 6] This graph shows an example of the wavelength dependence of the transmittance of the cut filter and the transmittance of the reflective film of the color synthesis element in a modified example of the projector shown in Figure 1. [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 4. 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 Figure 1, the projector 350 comprises an optical module 310 and a projection optical system 320. The optical module 310 comprises a red light emitter 101, a green light emitter 102, a blue light emitter 103, incident polarizing elements 171, 172, 173, light modulation elements 181, 182, 183, exit polarizing elements 175, 176, 177, and a photosynthesis element 200.

[0011] The red light emitter 101 emits red light LR. In the following description, the direction parallel to the optical axis of the red light LR emitted from the red light emitter 101 is referred to as the D1 direction. One side in the D1 direction is referred to as the -D1 side, and the side opposite to the -D1 side in the D1 direction is referred to as the +D1 side. The direction perpendicular to the D1 direction within the plane containing the optical axis of the red light LR is referred to as the D2 direction. One side in the D2 direction is referred to as the -D2 side, and the side opposite to the -D2 side in the D2 direction is referred to as the +D2 side. The direction perpendicular to both the D1 and D2 directions is referred to as the D3 direction. The red light LR emitted from the red light emitter 101 travels along the D1 direction towards the +D1 side.

[0012] The red light emitting section 101 includes a light source 121, a light guide element 141, and a parallelizing element 161. The light source 121 is supported by the substrate 111. The light source 121 is provided on the +D1 side surface of the substrate 111, which is parallel to the surface including the D2 and D3 directions. The light-emitting surface of the light source 121 is arranged substantially parallel to the surface including the D2 and D3 directions, and is the surface opposite in the D1 direction to the surface of the light source 121 that is in contact with the +D1 side surface of the substrate 111.

[0013] Light source 121 corresponds to the second light source and emits red light LR in the red wavelength band of the visible wavelength band. The red wavelength band corresponds to the second wavelength band. Red light LR corresponds to the second light. The red light LR diverges from the light source 121's light-emitting surface at a predetermined radiation angle, around an axis parallel to the D1 direction passing through the center of the light-emitting surface of light source 121, and is emitted towards the +D1 side. The red wavelength band is, for example, the wavelength band from 590 nm to 700 nm, and includes, for example, 630 nm.

[0014] The light source 121 is composed of, for example, LEDs that emit red light (LR). The LEDs that emit red light (LR) contain, for example, aluminum gallium indium phosphide (AlGaInP), which has excellent light extraction efficiency, as the light-emitting material. The light source 121 may consist of a single LED or of multiple LEDs. When the light source 121 consists of multiple LEDs, the multiple LEDs are arranged in the region occupied by the light source 121 in a plane including the D2 and D3 directions.

[0015] By using an LED for the light source 121, the cost of the light source 121 can be 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, receives heat from the light source 121 that emits the red light LR, and also acts as a heat radiating member that 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 second light guide element, and has an incident end 141a on the -D1 side in the D 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 second 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, and 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 direction and the D3 direction may be equivalent to the size of the light emitting surface of the light source 121 in the plane including the D2 direction and the D3 direction, but is preferably moderately larger than the size of the light emitting surface of the light source 121 in the plane including the D2 direction and the D3 direction. The dimension along the long side parallel to the D2 direction of the opening through which the red light LR is incident on the incident end 141a is 1 mm or more and 3 mm or less, and is, for example, about 2 mm.

[0020] The exit end 141b corresponds to the second 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 optical modulation element 181 when viewed along the D1 direction of the modulation surface 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 light 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 light 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 light 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 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 second 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 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, for example, in contact with the optical modulation element 181 from the -D1 side, but may be positioned with an appropriate distance from the optical modulation element 181 in the D1 direction. 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.

[0043] The incident polarizing element 171 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 incident polarizing element 171 transmits a portion of the incident red light LR, including a predetermined polarization, to the +D1 side, and reflects or absorbs the other portion of the red light LR to the -D1 side. If it is desired to suppress the generation of reflected light and stray light to the light source 121, it is desirable that the incident polarizing element 171 be an absorbing polarizer.

[0044] 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 emitted on the -D1 side of the incident polarizing element 171, or is absorbed by the incident polarizing element 171.

[0045] 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 corresponds to the first optical modulation element and modulates the red light LR emitted from the incident polarizing element 171 based on image information transmitted from an image forming apparatus such as a computer (not shown) connected to the optical modulation element 181 from an external source.

[0046] 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.

[0047] The ejection-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. For example, the ejection-side polarizing element 175 is in contact with the optical modulation element 181 from the +D1 side, but may also be positioned with an appropriate gap between it and the optical modulation element 181 in the D1 direction. The ejection-side polarizing element 175 emits a predetermined polarization of the image light IR emitted from the optical modulation element 181 along the D1 direction toward the +D1 side. The predetermined polarization is, for example, S polarization.

[0048] 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.

[0049] 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.

[0050] 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 is supported by the substrate 112. The light source 122 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 source 122 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 source 122 that is in contact with the +D2 side surface of the substrate 112.

[0051] Light source 122 corresponds to the first light source and emits green light LG in the green wavelength band of the visible wavelength band. The green wavelength band corresponds to the first wavelength band. Green light LG corresponds to the first light. The green wavelength band is, for example, the wavelength band from 500 nm to 590 nm, and includes, for example, 532 nm.

[0052] The light source 122 is composed of, 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 from the red light emission unit 101 and the blue wavelength band and intensity of the blue light LB emitted from the blue light emission unit 103, the light source 122 is composed of an LED with a built-in phosphor, and for example, an LED body made of semiconductor and a phosphor.

[0053] The LED body is provided on the +D2 side of the substrate 112. The LED body may be, for example, an LED that emits blue light having the same blue wavelength band as the light source 121. The LED body contains a GaN-based semiconductor material that has excellent light extraction efficiency. By having the light source 122 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.

[0054] The phosphor of the light source 122 is laminated on the +D2 side emission surface of the LED body. The phosphor is excited by the light emitted from the LED body as excitation light and emits green light LG as fluorescence from the emission surface. The type and material of the LED body, and the type and material of the phosphor are appropriately selected so that the phosphor excited by the light emitted from the LED body emits green light LG in the green wavelength band. 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+ ) may be included.

[0055] The light source 122 may consist of a single LED, similar to the light source 121, or it may consist of multiple LEDs. If the light source 122 consists of multiple LEDs, the multiple LEDs are arranged in the region occupied by the light source 122 within the plane including the D1 and D3 directions.

[0056] The substrate 112 is made of, for example, metal and also acts as a heat dissipation member that receives heat from the light source 122 emitting green light LG and releases that heat into the surrounding space.

[0057] 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 first 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.

[0058] The incident end 142a corresponds to the first 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 mm². 2 ~10mm x 10mm 2 That is the case.

[0059] 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.

[0060] The exit end 142b corresponds to the first 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] The shape of the optical modulation element 182 when viewed along the D2 direction of the modulation surface 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 D1 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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, for example, in contact with the optical modulation element 182 from the +D2 side, but may be positioned with an appropriate gap between it and the optical modulation element 182 in the D2 direction. 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.

[0082] The incident polarizing element 172 is, for example, a reflective polarizer or an absorptive polarizer 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 or absorbs the other portion of the green light LG to the -D2 side.

[0083] Furthermore, if it is desirable to suppress the generation of reflected light and stray light to the light source 122, the incident polarizing element 172 is preferably an absorbing polarizer. However, if the light source 122 has a phosphor, as in the green light emission unit 102, the light reflected from the reflective polarizer can be used to excite the phosphor, so the incident polarizing element 172 may be a reflective polarizer.

[0084] 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.

[0085] 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, or absorbed by the incident polarizing element 172.

[0086] 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.

[0087] 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.

[0088] The optical modulation element 182 is located on the optical path of the green light LG emitted from the incident polarizing element 172, positioned +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 corresponds to a second optical modulation element and modulates the green light LG emitted from the incident polarizing element 172 based on image information transmitted from an image forming apparatus such as a computer (not shown) connected to the optical modulation element 182 from an external source.

[0089] 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 first 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.

[0090] The ejection-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. For example, the ejection-side polarizing element 176 is in contact with the optical modulation element 182 from the +D2 side, but may also be positioned with an appropriate gap between it and the optical modulation element 182 in the D2 direction. The ejection-side polarizing element 176 emits a predetermined polarization of the image light IG emitted from the optical modulation element 182 along the D2 direction towards the +D2 side. The predetermined polarization is, for example, P polarization.

[0091] 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.

[0092] 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.

[0093] 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 is supported by the substrate 113. The light source 123 is provided on the -D1 side surface of the substrate 113, which is parallel to the surface including the D2 and D3 directions. The light-emitting surface of the light source 123 is arranged substantially parallel to the surface including the D2 and D3 directions, and is the surface opposite in the D1 direction to the surface of the light source 123 that is in contact with the +D2 side surface of the substrate 113. The light source 123 corresponds to a third light source and emits blue light LB in the blue wavelength band in the visible wavelength band. The blue wavelength band is, for example, the wavelength band of 430 nm to 500 nm, and includes, for example, 467 nm.

[0094] The light source 123 is composed of, for example, an LED that emits blue light LB. The LED that emits blue light LB contains a gallium nitride (GaN) semiconductor material as the light-emitting element, which has excellent light extraction efficiency. The light source 123 may consist of a single LED or of multiple LEDs. When the light source 123 consists of multiple LEDs, the multiple LEDs are arranged in the region occupied by the light source 123 in a plane including the D2 and D3 directions.

[0095] By using LEDs as the light source 123, the cost of the light source 123 is reduced, and the speckle noise of the blue light IM projected onto the screen SCR is reduced.

[0096] The substrate 113 is made of, for example, metal and also acts as a heat dissipation member that receives heat from the light source 123 emitting blue light LB and releases that heat into the surrounding space.

[0097] 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 third light guide element and has an incident end 143a on the +D1 side in the D1 direction, an exit end 143b on the -D1 side, and a side surface 143s and a reflective surface 143r extending between the incident end 143a and the exit end 143b in the D1 direction.

[0098] The incident end 143a corresponds to the third 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.

[0099] 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.

[0100] The exit end 143b corresponds to the third 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] The shape of the optical modulation element 183 when viewed along the D1 direction of the modulation surface 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.

[0108] 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 enter the reflective surface 143r even once, propagating directly from the entry 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, enters the reflective surface 143r one or more times from the entry 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 enclosed by the entry end 143a, the exit end 143b, and the reflective surface 143r differs depending on the angle of incidence to the entry end 143a, and extends to multiple paths with different numbers of reflections at the reflective surface 143r.

[0109] 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.

[0110] 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 143b towards the incident end 143a. 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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 third parallelizing element.

[0119] 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 blue light LB emission side. 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 blue light LB is emitted from the parallelizing element 163, and further on the +D1 side of the light guide element 143.

[0120] 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.

[0121] 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, for example, in contact with the optical modulation element 183 from the +D1 side, but may also be positioned with an appropriate gap between it and the optical modulation element 183 in the D1 direction.

[0122] 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 or an absorbing polarizer having a plate surface parallel to the plane 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 or absorbs the other portion of the blue light LB to the +D1 side. If it is desired to suppress the generation of reflected light and stray light to the light source 123, it is desirable that the incident polarizing element 173 be an absorbing polarizer.

[0123] 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 emitted on the +D1 side of the incident polarizing element 173, or is absorbed by the incident polarizing element 173.

[0124] The optical modulation element 183 is located on the optical path of the blue light LB emitted from the incident polarizing element 173, and is positioned -D1 side of the incident polarizing element 173, and overlaps with the incident polarizing element 173 in the D2 and D3 directions. The optical modulation element 183 corresponds to a third optical modulation element and modulates the blue light LB emitted from the incident polarizing element 173 based on image information transmitted from an image forming apparatus such as a computer (not shown) connected to the optical modulation element 183 from an external source.

[0125] 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. Each pixel's switching element 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, thereby generating blue image light IB. Image light IB corresponds to the third light. The optical modulation element 183 emits the image light IB generated by the liquid crystal panel along the D1 direction towards the -D1 side.

[0126] The ejection-side polarizing element 177 is provided 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. For example, the ejection-side polarizing element 177 is in contact with the optical modulation element 183 from the -D1 side, but may also be positioned with an appropriate gap between it and the optical modulation element 183 in the D1 direction. The ejection-side polarizing element 177 emits a predetermined polarization of the image light IB emitted from the optical modulation element 183 along the D1 direction towards the -D1 side. The predetermined polarization is, for example, S polarization.

[0127] 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.

[0128] 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.

[0129] The photosynthetic element 200 is, for example, a cross dichroic prism 210. The cross dichroic prism 210 has an incident surface 210c facing the exit surface of the exit 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 a plane including the D2 and D3 directions and overlap each other in the D2 and D3 directions. The incident surface 210d and the exit surface 210b are parallel to a plane including the D1 and D3 directions and overlap each other in the D1 and D3 directions.

[0130] 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.

[0131] 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 corresponds to the first reflective film and 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.

[0132] 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.

[0133] The reflective film 211 is positioned on the right-angle configuration surface of the four right-angle prisms, moving 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 positioned on the right-angle configuration surface of the four right-angle prisms, moving from the -D2 side to the +D2 side as you move from the -D1 side to the +D1 side as described above.

[0134] 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.

[0135] 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.

[0136] The projection optical system 320 is positioned on the optical path of the image light IM emitted from the photosynthetic element 200. The projection optical system 320 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 manner.

[0137] The projection optical system 320 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.

[0138] Figure 2 is a schematic diagram of the main parts of the optical module 310 of the first embodiment, specifically a schematic diagram of the optical system including incident polarizing elements 171, 172, 173, optical modulation elements 181, 182, 183, exit polarizing elements 175, 176, 177, and photosynthesis element 200. Figure 2 is a top view of the main parts of the optical module 310 as seen along the D3 direction.

[0139] As shown in Figure 2, the beam width of the green light LG incident on the optical modulation element 182 in the plane including the D1 and D3 directions is approximately constant in the D2 direction because the green light LG is parallelized by the parallelization element 162. The beam width of the green light LG emitted from the optical modulation element 182 in the plane including the D1 and D3 directions expands as it moves towards the +D2 side. The plane including the D1 and D3 directions intersects, specifically orthogonally, with the optical axis AXG of the green light LG incident on the optical modulation element 182, the optical axis of the green image light IG incident on the photosynthesis element 200, and the optical axis of the image light IM emitted from the photosynthesis element 200. The green light LG incident on the photosynthesis element 200 is divergent with respect to the optical axis AXG. Although not shown, the image lights IB and IR incident on the photosynthesis element 200 are also divergent with respect to the optical axis of each image light.

[0140] As described above, the green light LG incident on the photosynthetic element 200 is divergent light, and the reflective film 212 of the cross dichroic prism 210 constituting the photosynthetic element 200 is arranged so that it moves from the -D2 side to the +D2 side as it moves from the -D1 side to the +D1 side. Therefore, the incident angle of the image light IG incident on the reflective film 212 changes as it moves from the -D1 side to the +D1 side. When viewed from above along the D3 direction, the length of the reflective film 211 in the direction parallel to the surface of the reflective film 211 corresponding to the incident surface of the image light IG incident on the reflective film 211 is, for example, 31 mm. Similarly, the length of the reflective film 212 in the direction parallel to the surface 212a of the reflective film 212 corresponding to the incident surface of the image light IG incident on the reflective film 212 is, for example, 31 mm.

[0141] The surface 212a of the reflective film 212 on the incident side of the image light IG is positioned such that as the incident image light IG moves from the -D1 side to the +D1 side along the D1 direction perpendicular to the optical axis AXG of the image light IG, it moves from the -D2 side to the +D2 side. In other words, the surface 212a of the reflective film 212 is inclined with respect to the optical axis AXG.

[0142] The angle of incidence of the image light IG incident on the reflective film 212 is the angle that the image light IG makes with respect to the perpendicular between the surface 212a on the -D2 side of the reflective film 212 and the intersection surface 210k of the prism on which the reflective film 212 is provided. The angle of incidence θh of the image light IGh located at the -D1 end of the image light IG incident on the reflective film 212 is smaller than the angle of incidence of the image light IGc located approximately at the center in the D1 direction of the image light IG incident on the reflective film 212 and approximately overlapping with the optical axis AXG. The angle of incidence of the image light IGc into the reflective film 212 is approximately 45°. The angle of incidence θr of the image light IGr located at the +D1 end of the image light IG incident on the reflective film 212 is larger than the angle of incidence of the image light IGc.

[0143] Microscopically, there is a certain amount of variation in the direction of incidence of the image light IGh onto the reflective film 212, so the incident angle θh has a certain range relative to the aforementioned amount of variation. Here, the incident angle θh of the principal ray of the image light IGh, where the image light IGh has the greatest amount of light, represents the centroid of the incident angle θh, which is, for example, 40°. Similarly, there is a certain amount of variation in the direction of incidence of the image light IGh onto the reflective film 212, so the incident angle θh has a certain range relative to the aforementioned amount of variation. Here, the incident angle θh of the principal ray of the image light IGh, where the image light IGh has the greatest amount of light, represents the centroid of the incident angle θh, which is, for example, 40°.

[0144] Similar to the image light IGh, there is a certain degree of variation in the direction of incidence of the image light IGr onto the reflective film 212, so the incident angle θr has a certain range relative to the aforementioned variation. The incident angle θr of the principal ray of the image light IGr, where the incident angle θr of the image light IGr with the greatest amount of light is the centroid of the incident angle θr, which is, for example, 50°.

[0145] Figure 3 is a schematic graph showing an example of the emission spectrum of the light source 122 of the green light emitter 102, with the horizontal axis representing wavelength and the vertical axis representing emission intensity for each wavelength. In the example shown in Figure 3, the peak wavelength of the green light LG emitted from the light source 122 is approximately 540 nm. The full width at half maximum (FMAX) of the main peak of the green light LG is approximately 180 nm, which is wider than the FMAX of the spectrum of a typical green laser light. The spectrum of the green light LG is reflected in the spectrum of the image light IG.

[0146] Figure 4 is a schematic graph showing an example of the wavelength dependence of the transmittance of image light IGh, IGc, and IGr in the reflective film 212 when the thickness of the reflective film 212, i.e., the film thickness, is constant. As shown in Figure 4, the increasing and decreasing trends of the transmittance of image light IGh, IGc, and IGr in the reflective film 212 are the same for all of them in the visible wavelength band from 400 nm to 700 nm. However, as will be described later, the transmittances of image light IGh, IGc, and IGr in the increasing and decreasing ranges are different for all of them, and the transmittances of image light IGh, IGc, and IGr change depending on the centroid of the angle of incidence to the reflective film 212. The transmittances of image light IGh, IGc, and IGr in the reflective film 212 are equal and constant for all of them, between 90% and 100%, in the wavelength band from 500 nm to 560 nm.

[0147] The transmittance of image light IGh in the reflective film 212 decreases to about 20% when the wavelength becomes longer than 400 nm, similar to the transmittance of image light IGc, before increasing towards a maximum value of 90% to less than 100%. However, it increases at a higher rate than the transmittance of image light IGc, reaching its peak at a wavelength shorter than the transmittance of image light IGc, i.e., around 480 nm. The transmittance of image light IGh in the reflective film 212 decreases to about 650 nm when the wavelength becomes longer than 560 nm, similar to the transmittance of image light IGc, but decreases at a slightly higher rate than the transmittance of image light IGc, reaching about 30% at a wavelength shorter than the transmittance of image light IGc, i.e., around 645 nm. The transmittance of image light IGh in the reflective film 212 increases at a higher rate than the transmittance of image light IGc when the wavelength becomes longer than 650 nm.

[0148] The transmittance of image light IGr in the reflective film 212 decreases at a higher rate than the transmittance of image light IGc when the wavelength becomes longer than 400 nm, reaching about 10% at a wavelength of about 415 nm. The transmittance of image light IGr in the reflective film 212 decreases at a higher rate than the transmittance of image light IGc when the wavelength becomes longer than 415 nm, reaching a maximum value at a wavelength of about 500 nm, similar to the transmittance of image light IGc. The transmittance of image light IGr in the reflective film 212 decreases at a rate slightly higher than the transmittance of image light IGc and close to the transmittance of image light IGh up to 650 nm, reaching about 20% at a wavelength slightly longer than 650 nm. The transmittance of image light IGr in the reflective film 212 increases at a rate close to the transmittance of image light IGh when the wavelength becomes even longer than the aforementioned wavelengths exceeding 650 nm.

[0149] As shown in Figures 3 and 4, when the thickness of the reflective film 212 is constant, if the maximum transmittance Ta of each of the image light IGh, IGc, and IGr of the reflective film 212 is determined to be 98%, then the half-value Tf in the profile representing the wavelength dependence of the transmittance of each of the image light IGh, IGc, and IGr of the reflective film 212 is 49%. The profile representing the wavelength dependence of the transmittance of each of the image light IGh, IGc, and IGr of the reflective film 212 corresponds to the reflective film profile.

[0150] The shorter wavelength λah of the two wavelengths that satisfy the half-value Tf of the profile representing the wavelength dependence of the transmittance of the image light IGh of the reflective film 212 is longer than wavelength λac, unlike the shorter wavelength λac of the two wavelengths that satisfy the half-value Tf of the profile representing the wavelength dependence of the transmittance of the image light IGc of the reflective film 212. On the other hand, the shorter wavelength λar of the two wavelengths that satisfy the half-value Tf of the profile representing the wavelength dependence of the transmittance of the image light IGr of the reflective film 212 is shorter than wavelength λac, unlike wavelength λac.

[0151] Using image light IGc as a reference, at wavelength λac, the transmittance of image light IGh in the reflective film 212 is higher than that of image light IGc, while the transmittance of image light IGr in the reflective film 212 is lower than that of image light IGc. Therefore, in order to equalize the transmittances of image light IGh, IGc, and IGr in the color light included in image light IG and having wavelengths below λac, the thickness th of the reflective film 212 to which image light IGh is incident should be greater than the thickness of the reflective film 212 to which image light IGc is incident, and even greater than the thickness tr of the reflective film 212 to which image light IGr is incident.

[0152] In other words, when the wavelengths λah, λac, and λar become progressively shorter, that is, when the transmittance of the image light IGh, IGc, and IGr at wavelength λac increases progressively, it is sufficient for the thickness of the reflective film 212 to decrease from thickness th to thickness tr. This reduces the difference in transmittance of colored light having wavelengths below wavelength λac in the image light IGh, IGc, and IGr, and suppresses illuminance and color unevenness in the image light IGh, IGc, and IGr emitted from the reflective film 212.

[0153] The longer wavelength λbh of the two wavelengths that satisfy the half-value Tf of the profile representing the wavelength dependence of the transmittance of the image light IGh of the reflective film 212 is slightly shorter than the longer wavelength λbc of the two wavelengths that satisfy the half-value Tf of the profile representing the wavelength dependence of the transmittance of the image light IGc of the reflective film 212.

[0154] At wavelength λbc, the transmittance of image light IGh and IGr through the reflective film 212 is lower than the transmittance of image light IGc. At a wavelength of 650 nm, which is longer than λbc, the transmittance of image light IGh through the reflective film 212 is slightly higher than the transmittance of image light IGc, and the transmittance of image light IGr through the reflective film 212 is lower than the transmittance of image light IGc. Therefore, in order to equalize the transmittances of image light IGh, IGc, and IGr in the color light included in the image light IG that has a wavelength range of λbc or longer, the thickness th of the reflective film 212 to which image light IGh is incident should be greater than the thickness of the reflective film 212 to which image light IGc is incident, and even greater than the thickness tr of the reflective film 212 to which image light IGr is incident.

[0155] At wavelength λbc, wavelengths λbh, λbc, and λbr are not sequentially shorter. However, at wavelengths longer than λbc, such as 650 nm near the bottom of the long-wavelength peak in the reflective film profile, if the transmittance of image light IGh, IGc, and IGr decreases sequentially, then it is sufficient for the thickness of the reflective film 212 to decrease from thickness th to thickness tr. This reduces the difference in transmittance of the reflective film 212 for image light IGh, IGc, and IGr with wavelengths longer than λbc, thereby suppressing illuminance and color unevenness in the image light IGh, IGc, and IGr emitted from the reflective film 212.

[0156] The transmittance difference between image light IGh and IGr differs at wavelengths λac, λbc, and 650 nm. In the example above, the transmittance difference between image light IGh and IGr at wavelength λac is greater than that at wavelength λbc, and smaller than that at 650 nm. However, as can be seen by referring to the spectrum of green light LG in the example above, the intensity of green light LG at wavelength λac is smaller than that of green light LG at wavelengths λbc and 650 nm, and is close to zero. Therefore, the rate of change of the thickness th,tr of the reflective film 212 is set mainly according to the rate of change of transmittance of image light IGh and IGr in the wavelength band above wavelength λac, including the wavelength of 650 nm.

[0157] As described above, the thickness of the reflective film 212 decreases, for example, as you move from the -D1 side to the +D1 side and as you move from the -D2 side to the +D2 side, in order to minimize illuminance and color unevenness in the image light IGh, IGc, and IGr emitted from the reflective film 212, according to a profile representing the wavelength dependence of the transmittance of the reflective film 212 to the image light IG, which is calculated in advance by the spectrum of the image light IG and numerical calculations. The -D2 side in the D2 direction corresponds to the incident side of the image light IG. The +D2 side in the D2 direction corresponds to the exit side of the image light IG.

[0158] In the optical module 310 of this embodiment, including the example configuration described above, the centroid of the incident angles θh and θr of the image light IGh and IGr incident on the reflective film 212 is, for example, within the range of 35° to 55°. Within this range, in order to match the transmittance of the image light IGh and IGr of the reflective film 212 in the wavelength band from 630 nm to 700 nm according to the incident angles θh and θr, it is preferable that the change in thickness per unit length of the reflective film 212 is greater than 0 nm / mm and 1.0 nm / mm or less. The aforementioned unit length refers to the unit length in the direction parallel to the surface 212a of the reflective film 212.

[0159] The difference between the thickness th of the reflective film 212 on the incident side of the image light IG of the photosynthetic element 200, i.e., the -D1 side, and the thickness tr of the reflective film 212 on the exit side of the image light IG, i.e., the +D1 side, is, for example, 31 nm.

[0160] As described above, the thickness of the reflective film 212 decreases as it moves from the -D2 side to the +D2 side. Therefore, the illuminance and color unevenness in the image light IM emitted from the photosynthesis element 200 is reduced compared to the conventional case where the thickness of the reflective film 212 remains constant as it moves from the -D2 side to the +D2 side. As a result, the illuminance and color unevenness in the projected image displayed on the screen SCR by the image light IM emitted from the projection optical system 320 of the projector 350 shown in Figure 1 is reduced compared to the conventional case.

[0161] When the reflective film 211 is positioned facing upward along the D3 direction, it is symmetrically arranged with respect to the reflective film 212 with reference to a virtual central axis (not shown) parallel to the D2 direction and passing through the center of the cross dichroic prism 210 of the photosynthetic element 200. The incident surface of the reflective film 212 on the -D2 side moves from the exit side (+D2 side) of the image light IG to the incident side (-D2 side) of the image light IG as it moves from the -D1 side to the +D1 side along the D1 direction, which is perpendicular to the optical axis AXG of the incident image light IG. For the optimal thickness of the reflective film 211, refer to the above explanation regarding the thickness of the reflective film 212, replacing the red light LR and image light IR with the blue light LB and image light IB.

[0162] The optical module 310 of this embodiment, as described above, comprises a light source (first light source) 122, a light source (second light source) 121, a light source (third light source) 123, a light guide element (first light guide element) 142, a light guide element (second light guide element) 141, a light guide element (third light guide element) 143, a parallelization element (first parallelization element) 162, a parallelization element (second parallelization element) 161, a parallelization element (third parallelization element) 163, a light modulation element (first light modulation element) 182, a light modulation element (second light modulation element) 181, a light modulation element (third light modulation element) 183, and a photosynthesis element 200. The light source 122 emits green light (first light) LG in a wavelength band including the green wavelength band (first wavelength band). Light source 121 emits red light (second light) LR in a wavelength band that includes a red wavelength band (second wavelength band) different from the green wavelength band. Light source 123 emits blue light (third light) LB in a wavelength band that includes a blue wavelength band (third wavelength band) different from the green wavelength band and the red wavelength band. The light guide element 142 has an incident end (first incident end) 142a into which the green light LG emitted from light source 122 is incident, and an exit end (first exit end) 142b that emits the green light LG, and it equalizes the in-plane illuminance (in-plane illuminance) including the D1 direction and D3 direction of the green light LG. The light guide element 141 has an incident end (first incident end) 141a into which red light LR emitted from the light source 121 is incident, and an exit end (first exit end) 141b from which red light LR is emitted, and it equalizes the in-plane illuminance (in-plane illumination) including the D2 and D3 directions of the red light LR. The light guide element 143 has an incident end (first incident end) 143a into which blue light LB emitted from the light source 123 is incident, and an exit end (first exit end) 143b from which 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 light modulation element 182 modulates the green light LG emitted from the light guide element 142 based on image information. The light modulation element 181 modulates the red light LR emitted from the light guide element 141 based on image information. The light modulation element 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) IG emitted from the light modulation element 182, the image light (second light) IB emitted from the light modulation element 181, and the image light (third light) IB emitted from the light modulation element 183.

[0163] In the optical module 310 of this embodiment, the photosynthesis element 200 has a reflective film (first reflective film) 212. The reflective film 212 transmits the incident image light (first light) IG and reflects the incident image light IR. In the optical module 310 of this embodiment, the beam width of the image light IG emitted from the optical modulation element 182 in a plane including the D1 and D3 directions expands as the image light IG moves from the incident side to the photosynthesis element 200, i.e., the -D2 side, to the exit side from the photosynthesis element 200, i.e., the +D2 side. In the optical module 310 of this embodiment, the thickness of the reflective film 212 changes according to the incident angle of the image light IG incident on the reflective film 212.

[0164] In the optical module 310 of this embodiment, the incident angle of the image light IG changes and expands as it moves from the -D2 side to the +D2 side. The amount of light emitted from the reflective film 212 changes as it moves from the -D2 side to the +D2 side, depending on the transmittance of the image light IG in the reflective film 212. The transmittance of the image light IG in the reflective film 212 changes depending on the incident angle of the image light IG. The thickness of the reflective film 212 of the cross dichroic prism 210 of the photosynthesis element 200 is relatively small at positions where the transmittance of the image light IG in the reflective film 212 is relatively low, and relatively large at positions where the transmittance of the image light IG in the reflective film 212 is relatively high, depending on the incident angle of the image light IG.

[0165] In the optical module 310 of this embodiment, the image light IG incident on the cross dichroic prism 210, which is the photosynthesis element 200, is divergent light. Even if some of the image light IG is emitted out of the optical path of the same width along the D2 direction from which it should originally be emitted, the thickness of the reflective film 212 of the cross dichroic prism 210 of the photosynthesis element 200 changes as described above. Therefore, the difference in light intensity of colored light having the same wavelength among the image lights IGh, IGc, and IGr emitted from the photosynthesis element 200 is reduced, and the illuminance unevenness and color unevenness of the image lights IGh and IGr emitted from the photosynthesis element 200 are reduced. According to the optical module 310 of this embodiment, the occurrence of illuminance unevenness and color unevenness in the plane including the D1 and D3 directions of the image light IM emitted from the optical module 310 can be suppressed.

[0166] In the optical module 310 of this embodiment, when the full width at half maximum (FWHM) of the spectra of the green light LG and the image light IG is relatively wide compared to the FWHM of the laser light spectrum, such as when the FWHM of the spectra of the green light LG and the image light IG is 150 nm or more, a significant effect is obtained in suppressing the occurrence of illuminance unevenness and color unevenness in the image light IM emitted from the photosynthesis element 200.

[0167] In the optical module 310 of this embodiment, the thickness (film thickness) th of the reflective film 212 on the incident side of the image light (first light) IG, i.e., the -D2 side, is greater than the thickness (film thickness) tr of the reflective film 212 on the emission side of the image light IG, i.e., the +D2 side.

[0168] In the optical module 310 of this embodiment, for example, the centroid of the incident angle θh of the image light IGh incident on the -D2 side reflective film 212 in a plane including the D1 and D3 directions is smaller than the centroid of the incident angle θr of the image light IGr incident on the +D2 side reflective film 212 in the same plane. For example, at 650 nm, which is a wavelength longer than the peak wavelength of the spectrum of the image light IG, the transmittance of the image light IGh incident on the reflective film 212 at an incident angle θh is higher than the transmittance of the image light IGr incident on the reflective film 212 at an incident angle θr. According to the optical module 310 of this embodiment, since the thickness th of the reflective film 212 is greater than the thickness tr, illuminance unevenness and color unevenness in the image light IG emitted from the reflective film 212 are reduced, and the occurrence of illuminance unevenness and color unevenness in the image light IM emitted from the optical module 310 can be suppressed.

[0169] In the optical module 310 of this embodiment, if the transmittance of image light IGh incident on the reflective film 212 at an incident angle θh is lower than the transmittance of image light IGr incident on the reflective film 212 at an incident angle θr, then the thickness th of the reflective film 212 is smaller than the thickness tr. That is, in the optical module 310 of this embodiment, the thicknesses th and tr of the reflective film 212 are appropriately set based on the thickness of one reflective film 212 to which image light IGc is incident, according to the transmittance of image light IG at a predetermined wavelength included in the spectrum of the reflective film 212 corresponding to the centroid of the incident angle θh of image light IGh and the centroid of the incident angle θr of image light IGr.

[0170] In the optical module 310 of this embodiment, the centroid of the incident angle of the image light IG incident on the reflective film 212 is within the range of 35° to 55°. The change in thickness per unit length of the reflective film 212 is greater than 0 nm / mm and less than or equal to 1.0 nm / mm.

[0171] In the optical module 310 of this embodiment, the thickness of the reflective film 212 is set to be suitable for the transmittance of the image light IGh and IGr of the reflective film 212 according to the incident angles θh and θr of the image light IGh and IGr. According to the optical module 310 of this embodiment, illuminance unevenness and color unevenness in the image light IG emitted from the reflective film 212 can be reduced, and the occurrence of illuminance unevenness and color unevenness in the image light IM emitted from the optical module 310 can be effectively suppressed.

[0172] In the optical module 310 of this embodiment, when viewed from above along the D3 direction, the length of the reflective film 212 is 31 mm. The surface 212a, which is the incident surface of the reflective film 212, is positioned such that as it moves from the -D1 side to the +D1 side along the D1 direction, which is perpendicular to the optical axis AXG of the incident image light IG, it moves from the incident side of the image light IG to the exit side of the image light IG. That is, the surface 212a of the reflective film 212 is inclined with respect to the optical axis AXG. The difference between the thickness of the reflective film 212 on the incident side of the image light IG, i.e., the -D1 side, and the thickness of the reflective film 212 on the exit side of the image light IG, i.e., the +D1 side, of the photosynthesis element 200 is 31 nm.

[0173] In the optical module 310 of this embodiment, the size and thickness of the reflective film 212 are set to be suitable for the transmittance of the image light IGh and IGr of the reflective film 212 according to the incident angles θh and θr of the image light IGh and IGr. According to the optical module 310 of this embodiment, illuminance unevenness and color unevenness in the image light IG emitted from the reflective film 212 can be reduced, and the occurrence of illuminance unevenness and color unevenness in the image light IM emitted from the optical module 310 can be effectively suppressed.

[0174] In the optical module 310 of this embodiment, the cross-sectional shape of the light guide element 142 perpendicular to the optical axis and the D2 direction is rectangular.

[0175] In the optical module 310 of this embodiment, the light guide element 142 can easily generate green light LG 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 182 can be easily generated.

[0176] In the optical module 310 of this embodiment, the cross-sectional area of ​​the exit end 142b of the light guide element 142 is larger than the cross-sectional area of ​​the incident end 142a of the light guide element 142.

[0177] In the optical module 310 of this embodiment, the illuminance distribution of the green light LG is made uniform from the time it enters the light guide element 142a through to the time it is emitted from the exit end 142b, thereby expanding the irradiation area of ​​the green light LG. According to the optical module 310 of this embodiment, the illuminance distribution of the green light LG emitted from the light source 122 can be made uniform on a plane perpendicular to the optical axis AXG, and the size of the green light LG on a plane perpendicular to the optical axis AXG, i.e., the irradiation area, can be easily expanded to match the modulation plane of the optical modulation element 182.

[0178] The projector 350 of this embodiment comprises the optical module 310 described above and a projection optical system 320. The projection optical system 320 projects image light (light) IM emitted from the photosynthetic element 200 of the optical module 310 onto a projection surface such as a screen SCR.

[0179] According to the projector 350 of this embodiment, the illuminance and color unevenness of the image light IM emitted from the photosynthetic element 200 of the optical module 310 are well reduced, so the occurrence of illuminance and color unevenness in the projected image caused by the image light IM projected from the projection optical system 320 can be suppressed.

[0180] (modified version) Next, a modified version of the optical module 310 described above will be explained with reference to Figures 5 and 6. Figure 5 is a schematic diagram of the main part of a modified version of the optical module 310 of this embodiment, and corresponds to Figure 2. As shown in Figure 5, in the modified version of the optical module 310, the cut filter 260 is placed on the optical path of the green light LG on the -D2 side of the optical modulation element 182, that is, on the optical path of the green light LG between the parallelizing element 162 (not shown in Figure 5) and the optical modulation element 182.

[0181] The cut filter 260 is positioned, for example, on the optical path of the green light LG between the parallelizing element 162 and the incident polarizing element 172. The beam width of the green light LG incident on the cut filter 260 in a plane including the D1 and D3 directions is approximately constant in the D2 direction because the green light LG is parallelized by the parallelizing element 162.

[0182] Figure 6 is a schematic graph showing an example of the wavelength dependence of the transmittance of green light LG in the cut filter 260, and the wavelength dependence of the transmittance of image light IGc in the reflective film 212 when the thickness of the reflective film 212 is constant. In Figure 6, the CF profile represents the profile that represents the wavelength dependence of the transmittance of green light LG in the cut filter 260.

[0183] As shown in Figure 6, the profile representing the wavelength dependence of the transmittance of green light LG in the cut filter 260 corresponds to the filter profile, and, similar to the profile representing the wavelength dependence of the transmittance of image light IGc in the reflective film 212, it has a peak wavelength of approximately 540 nm and a constant maximum value in the wavelength band of approximately 520 nm to 575 nm.

[0184] The full width at half maximum (FWHM) of the profile representing the wavelength dependence of the transmittance of green light LG in the cut filter 260 is, for example, approximately 180 nm, similar to the profile representing the wavelength dependence of the transmittance of image light IGc in the reflective film 212. When the maximum transmittance of green light LG in the cut filter 260 is 98%, equivalent to the maximum transmittance Ta of image light IGc in the reflective film 212, the FWHM Tf in the profile representing the wavelength dependence of the transmittance of green light LG in the cut filter 260 is 49%.

[0185] The shorter wavelength λai of the two wavelengths that satisfy the half-value Tf of the profile representing the wavelength dependence of the transmittance of green light LG in the cut filter 260 is equivalent to the wavelength λah of the reflective film 212. Specifically, the difference between wavelength λai and wavelength λah is 5 nm or less, preferably 3 nm or less. The longer wavelength λbi of the two wavelengths that satisfy the half-value Tf of the profile representing the wavelength dependence of the transmittance of green light LG in the cut filter 260 is equivalent to the wavelength λbh of the reflective film 212. Specifically, the difference between wavelength λbi and wavelength λbh is 5 nm or less, preferably 3 nm or less.

[0186] By ensuring that wavelengths λah and λai are equivalent and the difference between them is 5 nm or less, and that wavelengths λbh and λbi are equivalent and the difference between them is 5 nm or less, the peak of the spectrum of the image light IG incident on the reflective film 212 of the photosynthetic element 200 can be matched to the peak of the profile representing the wavelength dependence of the transmittance of the image light IGc in the reflective film 212. This brings the peak shape of the spectrum of the image light IG before it is incident on the reflective film 212 closer to the peak shape of the profile representing the wavelength dependence of the transmittance of the image light IGc in the reflective film 212, and by adjusting the thickness of the reflective film 212 within the expected range, illuminance unevenness and color unevenness of the image light IG emitted from the reflective film 212 can be reduced.

[0187] For example, the placement of the cut filter 260 is suitable when the difference between the wavelength λac and the wavelengths λah and λai with respect to the reflective film 212 is 10 nm or more, when the difference between the wavelength λbc and the wavelengths λbh and λbi is 10 nm or more, or when, in cases other than those mentioned above, it is difficult to reduce the difference in light intensity of the same wavelength color light IGh, IGc, and IGr emitted from the reflective film 212 to a desired value or less by adjusting the thickness of the reflective film 212 alone.

[0188] In the modified optical module 310 of this embodiment described above, a cut filter 260 is further provided, which is placed on the optical path of the green light LG between the parallelizing element 162 and the optical modulation element 182. The wavelength λaf on the short wavelength side that satisfies the half-value Tf of the profile representing the wavelength dependence of the transmittance of the image light IGc in the reflective film 212 (reflective film profile) and the wavelength λai on the short wavelength side that satisfies the half-value Tf of the profile representing the wavelength dependence of the transmittance of the green light LG of the cut filter 260 (filter profile) are equivalent to each other. The wavelength λbf on the short wavelength side that satisfies the half-value Tf of the profile representing the wavelength dependence of the transmittance of the image light IGc in the reflective film 212 and the wavelength λbi on the short wavelength side that satisfies the half-value Tf of the profile representing the wavelength dependence of the transmittance of the green light LG of the cut filter 260 are equivalent to each other.

[0189] According to a modified version of the optical module 310 of this embodiment, a cut filter 260 is provided, which allows the main peak shape of the spectrum of the image light IG incident on the reflective film 212 to be matched to the main peak shape of the reflective film profile of the reflective film 212, thereby adjusting the thickness of the reflective film 212 within a reasonable range and reducing illuminance and color unevenness of the image light IG emitted from the reflective film 212 and the image light IM emitted from the photosynthesis element 200.

[0190] Although not shown, in a projector equipped with an optical module which is a modified version of the optical module 310 of this embodiment, the illuminance unevenness and color unevenness of the image light IM emitted from the photosynthesis element 200 are also well reduced, thus suppressing the occurrence of illuminance unevenness and color unevenness in the projected image caused by the image light IM projected from the projection optical system 320.

[0191] 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.

[0192] 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 emit red light LR and blue light LB when the LEDs constituting the light sources 121 and 123 are excited by light from the LED body. Furthermore, the polarization components transmitted by the incident polarizers placed in the optical paths of each color of light may or may not be common components.

[0193] 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.

[0194] [Summary of this disclosure] A summary of this disclosure is provided below. (Note 1) A first light source that emits first light in a first wavelength band, 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 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 into which the first light is emitted, and which makes the in-plane illuminance of the first light uniform, and a second incident end into which the second light emitted from the second light source is incident A second light guide element having an emitting end and a second emitting end for emitting the second light, which equalizes the in-plane illuminance of the second light; a third light guide element having a third emitting end into which the third light emitted from the third light source is incident, and a third emitting end for emitting the third light, which equalizes the in-plane illuminance of the third light; a first parallelizing element for parallelizing the first light emitted from the first light guide element; a second parallelizing element for parallelizing the second light emitted from the second light guide element; and the third light guide element An optical module comprising: a third parallelizing element that parallelizes the third light emitted from the first parallelizing element; a first optical modulation element that modulates the first light emitted from the first parallelizing element based on image information; a second optical modulation element that modulates the second light emitted from the second parallelizing element based on image information; a third optical modulation element that modulates the third light emitted from the third parallelizing element based on image information; and a photosynthesis element that synthesizes and emits the first light emitted from the first optical modulation element, the second light emitted from the second optical modulation element, and the third light emitted from the third optical modulation element, wherein the photosynthesis element has a first reflective film that transmits the first light and reflects the second light, the beam width of the first light emitted from the first optical modulation element expands as it moves from the incident side of the first light to the exit side of the first light to the photosynthesis element, and the thickness of the first reflective film changes according to the incident angle of the first light.

[0195] As a result of the configuration described in Appendix 1, the thickness of the first reflective film changes appropriately in accordance with the relative relationship between the transmittance and the incident position and angle of the first light. This reduces illuminance and color unevenness in the first light emitted from the photosynthetic element, and suppresses the occurrence of illuminance and color unevenness in the image light emitted from the optical module.

[0196] (Note 2) The optical module of Note 1, wherein the film thickness of the first reflective film on the incident side of the first light is greater than the film thickness on the exit side of the first light.

[0197] With the configuration described in Appendix 2, even if the transmittance of colored light with a predetermined wavelength included in the first light in the first reflective film on the emission side is lower than the transmittance of colored light with a predetermined wavelength on the incident side of the first light, the illuminance unevenness and color unevenness of the first light emitted from the first reflective film can be reduced.

[0198] (Note 3) The optical module according to Note 1 or Note 2, further comprising a cut filter disposed on the optical path of the first light between the first parallelizing element and the first optical modulation element, wherein the wavelength on the short-wavelength side of the half value of the reflective film profile representing the wavelength dependence of the transmittance of the first reflective film and the wavelength on the short-wavelength side of the half value of the filter profile representing the wavelength dependence of the transmittance of the cut filter are equivalent to each other, and the wavelength on the long-wavelength side of the half value of the reflective film profile and the wavelength on the long-wavelength side of the half value of the filter profile are equivalent to each other.

[0199] With the configuration described in Appendix 3, even if it is difficult to reduce the illuminance and color unevenness of the first light emitted from the first reflective film by adjusting only the film thickness of the first reflective film, the presence of a cut filter allows the spectrum of the first light incident on the first reflective film to be modified to an extent that reduces the illuminance and color unevenness of the first light emitted from the first reflective film to an acceptable range by adjusting the film thickness of the first reflective film within the expected range. As a result, the illuminance and color unevenness of the first light emitted from the first reflective film and the photosynthetic element can be reduced.

[0200] (Note 4) The centroid of the angle of incidence of the first light incident on the first reflective film is 35° to 55°. An optical module according to any of the specifications in Appendix 1 to Appendix 3, wherein the change in thickness per unit length of the first reflective film is greater than 0 nm / mm and less than or equal to 1.0 nm / mm.

[0201] As described in Appendix 4, the thickness of the first reflective film is appropriately set to match the transmittance of the first light, which changes according to the centroid of the angle of incidence of the first light onto the first reflective film, thereby reducing uneven illumination and color of the first light emitted from the first reflective film and the photosynthetic element.

[0202] (Note 5) In a top view, the length of the first reflective film is 31 mm, and the first reflective film is arranged to move from the incident side of the first light to the exit side of the first light as it moves along a direction perpendicular to the optical axis of the incident first light, and the difference between the thickness of the first reflective film on the incident side of the photosynthetic element and the thickness of the first reflective film on the exit side of the photosynthetic element is 31 nm, any optical module of Notes 1 to 4.

[0203] The configuration described in Appendix 5 allows the thickness of the first reflective film to be appropriately set based on the length of the first reflective film and the angle of incidence of the first light onto the first reflective film, thereby reducing illuminance and color unevenness of the first light emitted from the first reflective film and the photosynthetic element.

[0204] (Note 6) The cross-sectional shape of the first light guide element is rectangular, any of the optical modules specified in Notes 1 to 5.

[0205] With the configuration described in Appendix 6, a rectangular first light beam having a uniform illuminance distribution in a plane perpendicular to the central axis of the first light guide element can be easily generated using the first light guide element.

[0206] (Note 7) An optical module of any of Notes 1 to 6, wherein the cross-sectional area of ​​the first exit end is greater than the cross-sectional area of ​​the first entrance end.

[0207] With the configuration described in Appendix 7, the size of the irradiation area of ​​the first light emitted from the first light source can be matched to the size of the modulation surface of the first light modulation element, making it easy to uniformize the illuminance distribution of the first light.

[0208] (Note 8) A projector comprising an optical module of any of Notes 1 to 7 and a projection optical system for projecting light emitted from the photosynthetic element.

[0209] As a result of the configuration described in Appendix 8, the uneven illumination and color unevenness of the image light emitted from the photosynthetic element of the optical module are reduced, thereby reducing the uneven illumination and color unevenness of the image projected from the projection optical system onto a projection surface such as a screen. [Explanation of Symbols]

[0210] 121...Light source (second light source), 122...Light source (first light source), 141...Light guide element (second light guide element), 142...Light guide element (first light guide element), 181...Light modulation element (second light modulation element), 182...Light modulation element (first light modulation element), 200...Photosynthesis element, 310...Optical module, 320...Projection optical system, 350...Projector.

Claims

1. A first light source that emits first light in the first wavelength band, 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 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 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 first parallelizing element that parallelizes the first light emitted from the first light guide element, 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 first optical modulation element modulates the first light emitted from the first parallelizing element based on image information, A second optical modulation element modulates the second light emitted from the second parallelizing element based on image information, A third optical modulation element modulates the third light emitted from the third parallelizing element based on image information, A photosynthetic element that synthesizes and emits the first light emitted from the first light modulation element, the second light emitted from the second light modulation element, and the third light emitted from the third light modulation element, Equipped with, The photosynthetic element has a first reflective film that transmits the first light and reflects the second light, The beam width of the first light emitted from the first light modulation element expands as it moves from the incident side of the first light to the emission side of the first light into the photosynthetic element. The thickness of the first reflective film changes according to the angle of incidence of the first light. Optical module.

2. The film thickness of the first reflective film on the incident side of the first light is greater than the film thickness on the exit side of the first light. The optical module according to claim 1.

3. The system further comprises a cut filter disposed on the optical path of the first light between the first parallelizing element and the first optical modulation element, The wavelength on the short-wavelength side of the half-value of the reflective film profile, which represents the wavelength dependence of the transmittance of the first reflective film, and the wavelength on the short-wavelength side of the half-value of the filter profile, which represents the wavelength dependence of the transmittance of the cut filter, are equivalent to each other. The wavelength on the long-wavelength side of the half-value of the reflective film profile and the wavelength on the long-wavelength side of the half-value of the filter profile are equivalent to each other. The optical module according to claim 1 or claim 2.

4. The centroid of the incident angle of the first light incident on the first reflective film is 35° to 55°. The change in thickness per unit length of the first reflective film is greater than 0 nm / mm and less than or equal to 1.0 nm / mm. The optical module according to claim 1 or claim 2.

5. In a top view, the length of the first reflective film is 31 mm, and the first reflective film is arranged to move from the incident side of the first light to the emission side of the first light as it moves along a direction perpendicular to the optical axis of the incident first light. The difference between the thickness of the first reflective film on the incident side of the photosynthetic element and the thickness of the first reflective film on the emission side of the photosynthetic element is 31 nm. The optical module according to claim 1 or claim 2.

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

7. 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.

8. The optical module according to claim 1 or claim 2, A projection optical system that projects light emitted from the photosynthetic element, Equipped with, projector.

Images