projector

Abstract

We provide projectors that offer high light utilization efficiency, are compact, and are low-cost. [Solution] The projector of the present invention comprises a light source that emits illumination light, a photosynthetic element to which the illumination light is incident, a light modulation unit that modulates the light incident from the photosynthetic element to generate image-modulated light, a light separation unit that separates the image-modulated light into image-generating light used for image generation and image-non-generating light not used for image generation, a projection optical device that projects the image-generating light, a light guide optical system that guides the image-non-generating light incident from the light separation unit to the photosynthetic element, and a polarization conversion element arranged on the optical path between the photosynthetic element and the light modulation unit to align the polarization direction of the light incident from the photosynthetic element. The illumination light is light with a first polarization direction relative to the photosynthetic element, and the image-non-generating light incident on the photosynthetic element is light with a second polarization direction relative to the photosynthetic element, which is combined with the illumination light incident from the light source in the photosynthetic element and then incident on the light modulation unit.

Description

Technical Field

[0001] The present invention relates to a projector.

Background Art

[0002] Conventionally, there has been a projection system that adjusts the intensity of illumination light for illuminating a display element by using a diffraction pattern such as a computer-generated hologram displayed on a spatial light modulator according to the intensity of an input video (see, for example, Patent Document 1 below). In this projection system, the light incident on the pixels for dark tones constituting the image is reduced, and the light incident on the pixels for bright tones constituting the image is increased.

Prior Art Documents

Patent Documents

[0003] [[ID=X]] [[ID=X]]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since the spatial light modulator used in the above projection system utilizes light diffraction, it needs to have a pixel size on the order of the wavelength of light and a number of pixels corresponding to the resolution of the illumination pattern, and a huge amount of calculation is required to create a computer-generated hologram. Therefore, there are problems such as an increase in the size of the device and an increase in cost. In addition, there is a problem that the light utilization efficiency is reduced due to diffraction losses caused by zero-order light, higher-order diffraction images, and the like.

Means for Solving the Problems

[0005] Note: Some tags (such as ,

[0003] , , ) seem to be placeholder tags without specific content in the original Japanese text, and they are left unchanged in the translation as per the instruction. If there is any specific information or correction needed for these tags, please provide additional context.To solve the above problems, according to a first aspect of the present invention, a light source that emits illumination light, a photosynthetic element into which the illumination light emitted from the light source is incident, a light modulation unit that modulates the light incident from the photosynthetic element to generate image-modulated light, a light separation unit that separates the image-modulated light incident from the light modulation unit into image-generating light used for image generation and image-non-generating light not used for image generation, a projection optical device that projects the image-generating light incident from the light separation unit, and guides the image-non-generating light incident from the light separation unit to the photosynthetic element. A projector is provided, comprising a light guide optical system and a polarization conversion element disposed in the optical path between the photosynthetic element and the light modulation unit, which aligns the polarization direction of the light incident from the photosynthetic element, wherein the illumination light emitted from the light source is light with a first polarization direction relative to the photosynthetic element, and the non-image generating light incident on the photosynthetic element by the light guide optical system is light with a second polarization direction perpendicular to the first polarization direction relative to the photosynthetic element, and is combined with the illumination light incident from the light source in the photosynthetic element and incident on the light modulation unit. [Brief explanation of the drawing]

[0006] [Figure 1] This figure shows the main components of the projector according to the first embodiment. [Figure 2] This diagram shows the main components of the projector in the first modified example. [Figure 3] This figure shows the main components of the projector according to the second embodiment. [Figure 4] This figure shows the main components of the projector according to the third embodiment. [Figure 5] This diagram shows the main components of a projector in the second modified example. [Figure 6] This is a schematic diagram showing the configuration of the projector 5 according to the fourth embodiment. [Figure 7] This is a schematic diagram showing the configuration of the projector according to the fifth embodiment. [Figure 8] This diagram shows the main components of a projector in the third modified example. [Modes for carrying out the invention]

[0007] Embodiments of the present invention will be described below with reference to the drawings. In each drawing, the dimensional scale may be changed depending on the component in order to make each component easier to see.

[0008] (First Embodiment) First, the projector according to the first embodiment of the present invention will be described with reference to Figure 1. Figure 1 is a schematic diagram showing the configuration of the projector 1 according to the first embodiment. In the following explanation of the arrangement of each component, the XYZ coordinate system may be used. In this specification, the axis along the optical axis of the illumination light LW emitted from the light source 10 is defined as the X-axis, the axis along the image projection direction of the projector 1 is defined as the Y-axis, and the axis perpendicular to the X-axis and Y-axis is defined as the Z-axis.

[0009] As shown in Figure 1, the projector 1 comprises a light source 10, a photosynthesis element 20, a deflection element 25, a light modulation unit 30, a light separation unit 40, a light guide optical system 50, a first optical system 60, a diffusion element 62, a second optical system 63, a first lens array 64, a second lens array 65, a polarization conversion element 66, a superimposed lens 67, and a projection optical device 70.

[0010] The projector 1 of this embodiment has an illumination optical axis AX, a first optical axis AX1, a second optical axis AX2, and a third optical axis AX3. The light source 10, the photosynthesis element 20, and the deflection element 25 are arranged on the first optical axis AX1. The deflection element 25, the first optical system 60, the diffusion element 62, the second optical system 63, the first lens array 64, the second lens array 65, the polarization conversion element 66, the superimposed lens 67, the light modulation unit 30, the light separation unit 40, and the projection optical device 70 are arranged on the illumination optical axis AX. In other words, the deflection element 25, the first optical system 60, the diffusion element 62, the second optical system 63, the first lens array 64, and the second lens array 65 are arranged on the optical path between the photosynthesis element 20 and the polarization conversion element 66. The light separation unit 40 and a portion of the light guide optical system 50 are positioned on the second optical axis AX2. The light guide optical system 50 and the photosynthesis element 20 are positioned on the third optical axis AX3.

[0011] The light source 10 includes a first light-emitting element 11R, a second light-emitting element 11G, a third light-emitting element 11B, a first parallelizing element 12R, a second parallelizing element 12G, and a third parallelizing element 12B.

[0012] The first light-emitting element 11R is, for example, a laser diode (LD) that emits red light LR in the red wavelength band of 650 nm to 780 nm. Red light LR is linearly polarized light. The first parallelizing element 12R parallelizes the red light LR emitted radially from the first light-emitting element 11R.

[0013] The second light-emitting element 11G is a laser diode (LD) that emits green light LG in the green wavelength band of 520 nm to 600 nm, for example. Green light LG is linearly polarized light. The second parallelizing element 12G parallelizes the green light LG emitted radially from the second light-emitting element 11G.

[0014] The third light-emitting element 11B is, for example, a laser diode (LD) that emits blue light LB in the blue wavelength band of 420 nm to 500 nm. The blue light LB is linearly polarized light. The third parallelizing element 12B parallelizes the blue light LB emitted radially from the third light-emitting element 11B.

[0015] In this embodiment, the projector 1 employs a configuration that does not utilize diffracted light, so multimode oscillating laser light-emitting elements can be used as the light-emitting elements 11R, 11G, and 11B of the light source 10. With this configuration, it is possible to obtain a higher output while suppressing the generation of speckle noise compared to single-mode oscillating laser light-emitting elements.

[0016] Based on such a configuration, the light source 10 is adapted to emit red light LR, green light LG, and blue light LB composed of parallel light as illumination light LW in chronological order. Note that the number of each light-emitting element 11R, 11G, 11B in the light source 10 is appropriately set according to the amount of light required for each color light LR, LG, LB from the light source 10. Each color light LR, LG, LB emitted from the light source 10 as illumination light LW corresponds to P-polarized light with respect to the photosynthesis element 20. That is, the illumination light LW emitted from the light source 10 corresponds to an example of "light in the first polarization direction with respect to the photosynthesis element" of the present invention.

[0017] The illumination light LW emitted from the light source 10 enters the photosynthesis element 20. The photosynthesis element 20 is a polarization separation element having the characteristic of transmitting P-polarized light of the incident light and reflecting S-polarized light of the incident light. In the present embodiment, since the illumination light LW emitted from the light source 10 is P-polarized light with respect to the photosynthesis element 20, the illumination light LW passes through the photosynthesis element 20.

[0018] The illumination light LW that has passed through the photosynthesis element 20 is reflected by the deflection element 25 and the traveling direction changes by 90 degrees. The deflection element 25 is composed of, for example, a mirror. The illumination light LW reflected by the deflection element 25 enters the first optical system 60. The first optical system 60 condenses the light incident from the photosynthesis element 20.

[0019] The first optical system 60 includes, for example, a first lens 60a and a second lens 60b. In the present embodiment, the first lens 60a and the second lens 60b are each composed of a convex lens. The first optical system 60 condenses the illumination light LW and makes it enter the diffusion element 62.

[0020] The diffusion element 62 transmits the illumination light LW incident from the -Y side in the Y-axis direction and emits it to the +Y side in a diffused state on the diffusion surface. The diffusion element 62 is, for example, a known diffusion plate or diffusion element corresponding to color light in the visible wavelength band. Since the illumination light LW emitted from the light source 10 is coherent light, it may cause speckle in the projected image. In this embodiment, however, the illumination light LW is diffused by the diffusion element 62 to reduce speckle noise.

[0021] The second optical system 63 includes, for example, a first collimating lens 63a and a second collimating lens 63b. The second optical system 63 is a parallelizing optical system that substantially parallelizes the illumination light LW diffused by the diffusion element 62. The first collimating lens 63a and the second collimating lens 63b are each made of convex lenses. The light parallelized by the second optical system 63 is incident on the first lens array 64.

[0022] The first lens array 64 has a plurality of first small lenses 64a for dividing the illumination light LW from the second optical system 63 into a plurality of partial light beams. The plurality of first small lenses 64a are arranged in a matrix in a plane perpendicular to the illumination optical axis AX.

[0023] The second lens array 65 has a plurality of second small lenses 65b corresponding to a plurality of first small lenses 64a of the first lens array 64. The plurality of second small lenses 65b are arranged in a matrix in a plane perpendicular to the illumination optical axis AX. The superimposing lens 67 is a lens that superimposes the light emitted from the second lens array 65 onto the light modulation unit 30. Based on this configuration, the second lens array 65, together with the superimposing lens 67, superimposes the images of each first small lens 64a of the first lens array 64 near the image forming area of ​​the light modulation unit 30.

[0024] The polarization conversion element 66 is an element that aligns the polarization direction of light incident from the photosynthesis element 20. Specifically, the polarization conversion element 66 converts the polarization direction of light emitted from the second lens array 65 to the polarization direction that passes through the incident polarizer 32 of the light modulation unit 30, which will be described later. The polarization direction that passes through the incident polarizer 32 corresponds to S polarization for the liquid crystal panel 31.

[0025] In this embodiment, a field lens 68 is positioned in the optical path of the illumination light LW between the superimposed lens 67 and the incident polarizer 32. The field lens 68 parallelizes the illumination light LW incident on the light modulation unit 30. As a result, the illumination light LW can be efficiently incident on the incident polarizer 32 of the light modulation unit 30.

[0026] In this way, by aligning the polarization direction of the illumination light LW with the transmission axis direction of the incident polarizer 32 using the polarization conversion element 66, the loss of illumination light LW due to the incident polarizer 32 can be reduced, and the light utilization efficiency of the illumination light LW can be increased.

[0027] The light modulation unit 30 of this embodiment includes a transmissive liquid crystal panel 31 and an incident polarizing plate 32 provided on the light incident side of the liquid crystal panel 31. The liquid crystal panel 31 modulates the various colored lights LR, LG, and LB that are incident in time sequentially as illumination light LW, based on image information input from, for example, an image input device (not shown) such as a personal computer or a portable terminal device.

[0028] Based on this configuration, the liquid crystal panel 31 of this embodiment emits blue, green, or red image-modulated light IL in a time-division manner. Here, the image-modulated light IL emitted from the liquid crystal panel 31 includes image-generating light IL1, which is used to generate an image, and non-image-generating light IL2, which is not used to generate an image. In other words, the image-generating light IL1 corresponds to the light that constitutes the pixels for the brightness gradation of the image, and the non-image-generating light IL2 included in the image-modulated light IL corresponds to the light that constitutes the pixels for the dark gradation of the image.

[0029] In conventional liquid crystal panels, the image-non-generating light constituting the dark-tone pixels is blocked by a polarizing plate on the light-emitting side, while the image-generating light constituting the bright-tone pixels is transmitted, thereby projecting the desired image onto the screen SCR. Therefore, in conventional liquid crystal panels, the image-non-generating light IL2, which is blocked by the polarizing plate on the emission side, cannot be used as illumination light LW, resulting in a problem of reduced utilization efficiency of the illumination light LW emitted from the light source 10.

[0030] In contrast, the projector 1 of this embodiment, as described later, improves the utilization efficiency of the illumination light LW emitted from the light source 10 by recycling the non-image generating light IL2 that is not used for image generation in the light modulation unit 30.

[0031] The following describes in detail the configuration for recycling non-image-generating light IL2. Image-modulated light IL emitted from the liquid crystal panel 31 is incident on the light separation unit 40. The light separation unit 40 separates the image-modulated light IL incident on from the liquid crystal panel 31 into image-generating light IL1 and image-non-generating light IL2. In this embodiment, the light separation unit 40 is composed of a polarizing beam splitter that transmits P-polarized light and reflects S-polarized light.

[0032] The light incident surface 40a of the light separation unit 40 is not parallel to, but intersects with, the optical axis of the image-modulated light IL emitted from the light modulation unit 30. Specifically, the light separation unit 40 is positioned at a 45-degree angle with respect to the illumination optical axis AX.

[0033] Image generation light IL1 corresponds to P-polarization for the light separation unit 40, and non-image generation light IL2 corresponds to S-polarization for the light separation unit 40. In this embodiment, the liquid crystal panel 31 generates image-modulated light IL by adjusting the modulation degree of the illumination light LW, that is, the ratio of P-polarization and S-polarization, according to the brightness of the image generation light IL1 which is used as image light by passing through the light separation unit 40.

[0034] Based on this configuration, the light separation unit 40 transmits the P-polarized light IL from the image-modulated light IL as image-generating light IL1, and reflects the S-polarized light IL from the image-modulated light IL as non-image-generating light IL2 in a direction along the second optical axis AX2, thereby allowing the image-generating light IL1 and non-image-generating light IL2 to travel in different directions. Therefore, the image-generating light IL1 and non-image-generating light IL2 can be effectively separated from the image-modulated light IL.

[0035] The image-generating light IL1, separated by passing through the light separation unit 40, is incident on the projection optical device 70. The projection optical device 70 magnifies and projects the image-generating light IL1 incident from the light separation unit 40 toward the screen SCR, which is the projection surface. An absorbing polarizer that transmits the polarization corresponding to the image-generating light IL1 and absorbs other changes may be provided on the light incident surface of the projection optical device 70.

[0036] The projection optical device 70 is composed of, for example, one or more optical lenses. The optical lenses include various types of lenses such as plano-convex lenses, biconvex lenses, meniscus lenses, aspherical lenses, rod lenses, and free-form surface lenses.

[0037] Meanwhile, the non-image generating light IL2, which is reflected and separated by the light separation unit 40, enters the light guide optical system 50. The light guide optical system 50 guides the non-image generating light IL2 entering from the light separation unit 40 to the photosynthesis element 20. The configuration of the light guide optical system 50 will be described later.

[0038] In this embodiment, the non-image generating light IL2 incident on the photosynthetic element 20 by the light guide optical system 50 is S-polarized with respect to the photosynthetic element 20. In other words, the non-image generating light IL2 corresponds to an example of the "light with a second polarization direction orthogonal to the first polarization direction with respect to the photosynthetic element" in the present invention.

[0039] Since the non-image generating light IL2 is S-polarized for the photosynthesis element 20, the non-image generating light IL2 is reflected by the photosynthesis element 20. The photosynthesis element 20 is positioned at a 45-degree angle to the third optical axis AX3, which is aligned with the optical axis of the non-image generating light IL2. Therefore, the non-image generating light IL2 is reflected to the +X side by the photosynthesis element 20 and combined with the illumination light LW incident from the light source 10. Hereinafter, the light obtained by combining the non-image generating light IL2 and the illumination light LW may be referred to as the combined illumination light LW1.

[0040] The light guide optical system 50 of this embodiment includes a relay optical system 51 having a plurality of relay lenses 51a, and a first mirror 52. The first mirror 52 reflects the non-image generating light IL2 incident from the light separation unit 40 toward the relay optical system 51. The relay optical system 51 images the light emitted from the image forming region that generates the image modulated light IL in the light modulation unit 30 onto the light incident surface of the first optical system 60. The light incident surface of the first optical system 60 corresponds to the light incident surface 60b1 of the second lens 60b.

[0041] In other words, in this embodiment, the relay optical system 51 is configured such that the light emission surface of the image forming region of the light modulation unit 30 and the light incident surface 60b1 of the second lens 60b are optically conjugate. Figure 1 shows an example where the relay optical system 51 has four relay lenses 51a, but the number and arrangement of the relay lenses 51a can be changed as appropriate according to the optical characteristics required of the relay optical system 51.

[0042] By using the light guide optical system 50 consisting of the relay optical system 51 in this way, the non-image generating light IL2 emitted from the image forming region of the light modulation unit 30 and passing through the light separation unit 40 and the photosynthesis element 20 can be efficiently incident onto the first optical system 60.

[0043] In the composite illumination light LW1, the luminous beam width W1 of the non-image generating light IL2 incident from the light modulation unit 30 is larger than the luminous beam width W2 of the illumination light LW emitted from the light source 10. As a result, the composite illumination light LW1 has an illuminance unevenness in which the brightness of the central part is relatively higher than the brightness of the peripheral part.

[0044] The combined illumination light LW1 is focused by the first optical system 60 and incident on the diffusion element 62, while the image-non-generating light IL2 and illumination light LW are emitted in a similar divergent state from the diffusion element 62. As a result, the beam width of the combined illumination light LW1 diffused from the diffusion element 62 is approximately constant, resulting in light with a uniform illuminance distribution.

[0045] The composite illumination light LW1, like the illumination light LW described above, is incident on the light modulation unit 30 via the first lens array 64, the second lens array 65, the polarization conversion element 66, the superimposed lens 67, and the field lens 68. The image-non-generating light IL2 and the illumination light LW contained in the composite illumination light LW1 have different polarization directions, but the polarization directions of the image-non-generating light IL2 and the illumination light LW are aligned with the transmission axis direction of the incident polarizer 32 by the composite illumination light LW1 passing through the polarization conversion element 66. As a result, the composite illumination light LW1 passes through the incident polarizer 32 and is incident on the liquid crystal panel 31 effectively. Furthermore, since the composite illumination light LW1 has a uniform illuminance distribution as described above, it is possible to generate high-quality image modulation light IL without illuminance unevenness in the liquid crystal panel 31 of the light modulation unit 30.

[0046] A portion of the synthesized illumination light LW1 is separated as non-image generating light IL2 in the light separation unit 40, and is combined with the illumination light LW emitted from the light source 10 in the photosynthesis element 20. This cycle of combined illumination light being incident on the light modulation unit 30 is repeated.

[0047] As described above, the projector 1 of this embodiment comprises a light source 10 that emits illumination light LW, a photosynthesis element 20 into which the illumination light LW emitted from the light source 10 is incident, a light modulation unit 30 that modulates the light incident from the photosynthesis element 20 to generate image modulation light IL, a light separation unit 40 that separates the image modulation light IL incident from the light modulation unit 30 into image generation light IL1 used for image generation and image non-generation light IL2 not used for image generation, a projection optical device 70 that projects the image generation light IL1 incident from the light separation unit 40, a light guide optical system 50 that guides the image non-generation light IL2 incident from the light separation unit 40 to the photosynthesis element 20, and a polarization conversion element 66 arranged on the optical path between the photosynthesis element 20 and the light modulation unit 30 to align the polarization direction of the light incident from the photosynthesis element 20. The illumination light LW emitted from the light source 10 is P-polarized for the photosynthetic element 20, and the non-image generating light IL2 incident on the photosynthetic element 20 by the light guide optical system 50 is S-polarized for the photosynthetic element 20. This light is combined with the illumination light LW incident on the light source 10 and then incident on the light modulation unit 30.

[0048] According to the projector 1 of this embodiment, the non-image generating light IL2 that is not used for image generation in the light modulation unit 30 can be recycled as illumination light LW. Therefore, the light utilization efficiency of the illumination light LW emitted from the light source 10 can be increased.

[0049] In this embodiment, instead of using light diffraction, a configuration is adopted that separates the image-modulated light IL2 from the image-non-generating light IL by utilizing the difference in polarization direction. Therefore, compared to using a conventional spatial light modulator, it is possible to miniaturize the device configuration and reduce costs. Furthermore, by not utilizing the diffraction of light, diffraction losses due to zero-order light and higher-order diffraction patterns are avoided, thus significantly increasing the efficiency of light utilization.

[0050] (First variation) Next, an alternative configuration relating to the first embodiment will be described as the first modified example. In this modified example, the configuration of the light separation unit differs from that of the first embodiment. Therefore, the following description will mainly focus on the peripheral configuration of the light separation unit, and components common to the drawings used in the above embodiment will be denoted by the same reference numerals, and their descriptions will be omitted.

[0051] Figure 2 shows the main components of projector 1A of this modified example. As shown in Figure 2, the light separation section 40A of the projector 1A in this modified example includes a polarization separation element 41, a phase difference element 42, and a reflecting element 43. The polarization separation element 41 is composed of a polarization beam splitter that transmits P-polarized image-generating light IL1 and reflects S-polarized non-image-generating light IL2. The image-generating light IL1 that has passed through the polarization separation element 41 is incident on the projection optical device 70 and projected onto the screen SCR as an image.

[0052] The polarization separation element 41 reflects the non-image-generating light IL2 from the image-modulating light IL incident from the optical modulation unit 30 toward the +X side and directs it toward the phase difference element 42. The phase difference element 42 is composed of a quarter-wave plate placed in the optical path between the polarization separation element 41 and the reflecting element 43. Therefore, the S-polarized non-image-generating light IL2 reflected by the polarization separation element 41 is incident toward the phase difference element 42. The S-polarized non-image-generating light IL2 is converted by the phase difference element 42 to, for example, right-handed circularly polarized non-image-generating light Lc1, and then incident toward the reflecting element 43. The reflecting element 43 reflects the non-image-generating light Lc1 that has passed through the phase difference element 42 toward the phase difference element 42. The right-handed circularly polarized non-image-generating light Lc1 is reflected by the reflecting element 43 as left-handed circularly polarized non-image-generating light Lc2.

[0053] Left-handed circularly polarized non-image generating light Lc2 is converted to P-polarized non-image generating light IL3 by the phase difference element 42. The P-polarized non-image generating light IL3 passes through the polarization separation element 41 and travels along the second optical axis AX2 before entering the optical guide optics 50. In this way, the non-image generating light IL3 that has been reflected by the reflecting element 43 and passed through the phase difference element 42 is separated from the image generating light IL1 by passing through the polarization separation element 41.

[0054] In this embodiment, since the non-image generating light IL3 is incident on the optical guide optical system 50 as P-polarized light, a 1 / 2 phase difference plate 44 placed in the optical path of the optical guide optical system 50 converts the non-image generating light IL3 into S-polarized light for the photosynthesis element 20. As a result, the non-image generating light IL3 can be combined with the illumination light LW emitted from the light source 10 in the photosynthesis element 20.

[0055] Even when using the light separation unit 40A of this modified example, similar to the first embodiment, the light utilization efficiency of the illumination light LW emitted from the light source 10 can be increased by recycling the non-image generating light that is not used for image generation as illumination light LW.

[0056] (Second Embodiment) Next, a projector according to a second embodiment of the present invention will be described. The basic configuration of the projector according to the second embodiment is the same as that of the first embodiment, but the configuration of the optical modulation unit and the optical separation unit differs from that of the first embodiment. Therefore, the following description will mainly focus on the configuration of the optical modulation unit and the optical separation unit, and components common to the drawings used in the above embodiment will be denoted by the same reference numerals and their descriptions will be omitted.

[0057] Figure 3 is a schematic diagram showing the configuration of the projector 2 in the second embodiment. As shown in Figure 3, the projector 2 comprises a light source 10, a photosynthetic element 20, a deflection element 25, a light modulation unit 35, a light separation unit 45, a light guide optical system 50, a second mirror 53, a first optical system 60, a diffusion element 62, a second optical system 63, a first lens array 64, a second lens array 65, a polarization conversion element 66, a superimposed lens 67, and a projection optical device 70.

[0058] The projector 2 of this embodiment has an illumination optical axis AX, a first optical axis AX1, a second optical axis AX2, a third optical axis AX3, a fourth optical axis AX4, and a fifth optical axis AX5. The light source 10, the photosynthesis element 20, and the deflection element 25 are arranged on the first optical axis AX1. The deflection element 25, the first optical system 60, the diffusion element 62, the second optical system 63, the first lens array 64, the second lens array 65, the polarization conversion element 66, the superimposed lens 67, and the light separation unit 40 are arranged on the fourth optical axis AX4. The light modulation unit 35, the light separation unit 40, and the projection optical device 70 are arranged on the illumination optical axis AX. The illumination optical axis AX is an axis that intersects the fourth optical axis AX4 at an oblique angle. The light separation unit 40 and the second mirror 53 are arranged on the fifth optical axis AX5. The second mirror 53 and a part of the light guide optical system 150 are arranged on the second optical axis AX2. The light guide optical system 50 and the photosynthetic element 20 are arranged on the third optical axis AX3.

[0059] The light separation unit 45 in this embodiment is composed of a prism group 46 consisting of two prisms arranged opposite each other with an air layer of a certain thickness in between, and has a reflective surface 46r. The angle of the reflective surface 46r is set so as to totally reflect the illumination light LW emitted from the superimposed lens 67 toward the light modulation unit 35.

[0060] The optical modulation unit 35 of this embodiment is composed of a micromirror type optical modulation element 36. The optical modulation unit 35 of this embodiment is composed of, for example, a digital micromirror device (DMD) and has a plurality of micromirrors 36a arranged in a matrix. The DMD generates image modulation light IL according to the orientation of the plurality of micromirrors 36a. Specifically, the DMD generates image modulation light IL including image generating light IL1 and image non-generating light IL2 by switching the tilt direction of each of the plurality of micromirrors 36a. In this embodiment, the DMD is configured to generate image modulation light IL of a color corresponding to illumination light LW incident from the light source 10 in a time-division manner. The DMD reflects image generating light IL1 in a direction that transmits through the reflective surface 46r of the prism group 46 in a predetermined direction, and reflects image non-generating light IL2 in a direction that transmits through the reflective surface 46r of the prism group 46 in a direction different from that of image generating light IL1.

[0061] The light separation unit 45 transmits the image-generating light IL1 from the image-modulated light IL incident from the light modulation unit 35 in a direction along the illumination optical axis AX, thereby emitting the image-generating light IL1 along the illumination optical axis AX, and transmits the non-image-generating light IL2 from the image-modulated light IL incident from the light modulation unit 35 in a direction different from the illumination optical axis AX, thereby emitting it along the fifth optical axis AX5. Thus, the light separation unit 45 of this embodiment can separate the image-modulated light IL into image-generating light IL1 and image-non-generating light IL2 by changing the emission direction of the image-modulated light IL incident from the light modulation unit 35.

[0062] The image generating light IL1, separated by being emitted from the light separation unit 45 along the illumination optical axis AX, is incident on the projection optical device 70 and projected onto the screen SCR. Furthermore, the image-non-generating light IL2, which is separated by being emitted from the light separation unit 45 along the fifth optical axis AX5, is incident on the second mirror 53. The second mirror 53 reflects the image-non-generating light IL2 incident from the light separation unit 45 toward the light guide optical system 50.

[0063] In this embodiment, the relay optical system 51 of the light guide optical system 50 is configured such that the surfaces of the multiple micromirrors 36a, which are the image forming regions of the light modulation section 35, and the light incident surface 60b1 of the second lens 60b are optically conjugate.

[0064] Thus, even in the projector 2 of this embodiment, when using the light modulation unit 35 composed of a DMD, the non-image generating light IL2 that is not used for image generation can be recycled as illumination light LW. Therefore, the light utilization efficiency of the illumination light LW emitted from the light source 10 can be increased. Furthermore, in the projector 2 of this embodiment, instead of using light diffraction, a configuration is adopted to separate the image-modulated light IL from the image-non-generating light IL2 by utilizing the difference in the direction of light emission from the light separation unit 45. Therefore, compared to the case where a conventional spatial light modulator is used, the device configuration can be made smaller and costs can be reduced. In addition, since diffraction loss due to zero-order light and higher-order diffraction patterns does not occur because light diffraction is not used, the light utilization efficiency can be greatly increased.

[0065] (Third embodiment) Next, a projector according to a third embodiment of the present invention will be described. The difference between the third embodiment and the first embodiment is that the light modulation unit has three liquid crystal panels, while the other basic configurations are the same. Therefore, the following will mainly describe the configuration of the light modulation unit and its surrounding configurations, and components common to the drawings used in the above embodiments will be denoted by the same reference numerals and their descriptions will be omitted.

[0066] Figure 4 is a schematic diagram showing the configuration of the projector 3 in the third embodiment. As shown in Figure 4, the projector 3 comprises a light source 10, a photosynthesis element 20, a light modulation unit, a light separation unit 47, a light guide optical system 150, a first optical system 60, a diffusion element 62, a second optical system 63, a first lens array 64, a second lens array 65, a polarization conversion element 66, a superimposed lens 67, a projection optical device 70, a color separation optical system 15, and a synthesis optical system 6.

[0067] In the projector 3 of this embodiment, the light source 10 simultaneously emits red light LR, green light LG, and blue light LB. In other words, the light source 10 emits white light including blue light, green light, and red light as illumination light LW.

[0068] The optical modulation unit of this embodiment includes a first optical modulation unit 30R, a second optical modulation unit 30G, and a third optical modulation unit 30B. The first optical modulation unit 30R modulates the red light R of the illumination light LW to generate a first image modulation light IR corresponding to the red light R. The second optical modulation unit 30G modulates the green light G of the illumination light LW to generate a second image modulation light IG corresponding to the green light G. The third optical modulation unit 30B modulates the blue light B of the illumination light LW to generate a third image modulation light IB corresponding to the blue light B. In this embodiment, red light R corresponds to the "first color light" of the present invention, green light G corresponds to the "second color light" of the present invention, and blue light B corresponds to the "third color light" of the present invention.

[0069] The color separation optical system 15 separates the white illumination light LW emitted from the light source 10 into red light R, green light G, and blue light B. The color separation optical system 15 includes a first dichroic mirror 7a and a second dichroic mirror 7b, a first reflective mirror 8a, a second reflective mirror 8b, and a third reflective mirror 8c, and a first relay lens 9a and a second relay lens 9b.

[0070] The first dichroic mirror 7a separates the illumination light LW from the light source 10 into red light R and other light (green light G and blue light B). The first dichroic mirror 7a transmits the red light R and reflects the other light (green light G and blue light B). On the other hand, the second dichroic mirror 7b separates the other light (green light G and blue light B) into green light G and blue light B by reflecting the green light G and transmitting the blue light B.

[0071] The first reflective mirror 8a is positioned in the optical path of red light R and reflects the red light R that has passed through the first dichroic mirror 7a toward the first light modulation unit 30R. Meanwhile, the second reflective mirror 8b and the third reflective mirror 8c are positioned in the optical path of blue light B and guide the blue light B that has passed through the second dichroic mirror 7b toward the third light modulation unit 30B. The green light G is reflected from the second dichroic mirror 7b toward the second light modulation unit 30G.

[0072] The first relay lens 9a and the second relay lens 9b are positioned on the light-emitting side of the second reflective mirror 8b in the optical path of the blue light B. The first relay lens 9a and the second relay lens 9b have the function of compensating for the light loss of blue light B caused by the optical path length of blue light B being longer than the optical path lengths of red light R and green light G.

[0073] The first light modulation unit 30R includes a transmissive liquid crystal panel 31R and an incident polarizing plate 32R provided on the light incident side of the liquid crystal panel 31R. The second light modulation unit 30G includes a transmissive liquid crystal panel 31G and an incident polarizing plate 32G provided on the light incident side of the liquid crystal panel 31G. The third light modulation unit 30B includes a transmissive liquid crystal panel 31B and an incident polarizing plate 32B provided on the light incident side of the liquid crystal panel 31B.

[0074] Furthermore, field lenses 68R, 68G, and 68B are positioned on the incident side of the first light modulation section 30R, the second light modulation section 30G, and the third light modulation section 30B, respectively. The field lenses 68R, 68G, and 68B parallelize the red light R, green light G, and blue light B incident on the first light modulation section 30R, the second light modulation section 30G, and the third light modulation section 30B, respectively.

[0075] The optical separation unit 47 includes a first optical separation element 47a that separates the first image modulation light IR incident from the first optical modulation unit 30R into a first image generating light IR1 and a first image non-generating light IR2; a second optical separation element 47b that separates the second image modulation light IG incident from the second optical modulation unit 30G into a second image generating light IG1 and a second image non-generating light IG2; and a third optical separation element 47c that separates the third image modulation light IB incident from the third optical modulation unit 30B into a third image generating light IB1 and a third image non-generating light IB2.

[0076] In the optical separation unit 47 of this embodiment, each optical separation element 47a, 47b, and 47c is composed of a polarizing beam splitter that transmits P-polarized light and reflects S-polarized light. Each image-generating light IR1, IG1, and IB1 corresponds to P-polarized light for each optical separation element, and each non-image-generating light IR2, IG2, and IB2 corresponds to S-polarized light for each optical separation element.

[0077] Based on this configuration, the light separation unit 47 transmits the P-polarized light of each image modulating light IR, IG, and IB as image generating light IR1, IG1, and IB1, and reflects the S-polarized light as image non-generating light IR2, IG2, and IB2, thereby separating each image modulating light IR, IG, and IB into image generating light and image non-generating light, respectively.

[0078] The light guide optical system 150 of this embodiment includes a relay optical system 51, a first combining element 55, a second combining element 56, and a third mirror 54. The first combining element 55 combines the first non-image generating light IR2 incident from the first light separation element 47a and the second non-image generating light IG2 incident from the second light separation element 47b, and guides them to the second combining element 56. The first combining element 55 is composed of a dichroic mirror that transmits the first non-image generating light IR2 and reflects the second non-image generating light IG2. The third mirror 54 reflects the third image non-generating light IB2, which has been reflected by the third light separation element 47c, toward the second synthesis element 56. The second synthesis element 56 synthesizes the first non-image generating light IR2 and the second non-image generating light IG2 incident from the first synthesis element 55, and the third non-image generating light IB2 incident from the third light separation element 47c, and guides them to the photosynthesis element 20. The second synthesis element 56 is composed of a dichroic mirror that transmits the third non-image generating light IB2 and reflects the first non-image generating light IR2 and the second non-image generating light IG2.

[0079] The non-generating light IR2 for the first image, the non-generating light IG2 for the second image, and the non-generating light IB2 for the third image are incident on the photosynthetic element 20 by the light guide optical system 150 and are combined with the illumination light LW emitted from the light source 10.

[0080] The first image generating light IR1, the second image generating light IG1, and the third image generating light IB1 from the first light modulation unit 30R, the second light modulation unit 30G, and the third light modulation unit 30B are incident on the composite optical system 6. The composite optical system 6 emits the combined image light, which is the first image generating light IR1, the second image generating light IG1, and the third image generating light IB1, toward the projection optical device 70. For example, a cross dichroic prism is used in the composite optical system 6.

[0081] In this embodiment, a phase difference plate 6a is provided on the incident planes of the first image generating light IR1 and the third image generating light IB1 in the composite optical system 6. The phase difference plate 6a is a half-wavelength phase difference plate that imparts a half-wavelength phase difference to the first image generating light IR1 and the third image generating light IB1. As a result, the first image generating light IR1 and the third image generating light IB1 are converted to S-polarization for the cross dichroic prism by passing through the phase difference plate 6a, while the second image generating light IG1 remains P-polarization for the cross dichroic prism. Therefore, the first image generating light IR1, the second image generating light IG1, and the third image generating light IB1 are well combined in the composite optical system 6 and projected onto the screen SCR by the projection optical device 70.

[0082] Thus, according to the projector 3 of this embodiment, even when a three-panel structure using three liquid crystal panels 31R, 31G, and 31B as the light modulation unit is adopted, the non-image generating light that is not used for image generation can be recycled as illumination light LW. Therefore, the light utilization efficiency of the illumination light LW emitted from the light source 10 can be increased.

[0083] Furthermore, in the projector 3 of this embodiment, instead of using light diffraction, the difference in the direction of light emission from the light separation unit 47 is used to separate the image-modulated light from the non-image-generating light. Therefore, compared to the case where a conventional spatial light modulator is used, the device configuration can be made smaller and costs can be reduced. In addition, since diffraction loss due to zero-order light and higher-order diffraction patterns does not occur because light diffraction is not used, the light utilization efficiency can be greatly increased.

[0084] (Second variation) Next, a different configuration relating to the third embodiment will be described as a second modification. In this modification, the configuration of the light guide optical system differs from that of the third embodiment. Therefore, the peripheral configuration of the light guide optical system will be mainly described below, and the same reference numerals will be used for components common to the drawings used in the above embodiments, and their descriptions will be omitted.

[0085] Figure 5 shows the main components of projector 3A in this modified example. As shown in Figure 5, the light guide optical system 150A of the projector 3A in this modified example includes a relay optical system 51, a third combining element 57, a fourth combining element 58, a third mirror 54, and a fourth mirror 59.

[0086] In this modified example, the first non-image generating light IR2 separated by the first light separation element 47a is incident on the third combining element 57. The second non-image generating light IG2 separated by the second light separation element 47b is incident on the fourth mirror 59. The fourth mirror 59 reflects the second non-image generating light IG2 toward the fourth combining element 58. The third mirror 54 reflects the third image non-generating light IB2, which was reflected by the third light separation element 47c, toward the third combining element 57. The third combining element 57 combines the first image non-generating light IR2 and the third image non-generating light IB2 and guides them toward the fourth combining element 58. The third combining element 57 is composed of a dichroic mirror that reflects the first image non-generating light IR2 and transmits the third image non-generating light IB2. The fourth synthesis element 58 synthesizes the first non-image generating light IR2 and the third non-image generating light IB2 incident from the third synthesis element 57, and the second non-image generating light IG2 incident from the fourth mirror 59, and guides them to the photosynthesis element 20. The fourth synthesis element 58 is composed of a dichroic mirror that transmits the first non-image generating light IR2 and the third non-image generating light IB2 and reflects the second non-image generating light IG2.

[0087] Thus, in the modified optical system 150A, instead of combining the third image non-generating light IB2 with the combined light obtained by combining the first image non-generating light IR2 and the second image non-generating light IG2, as in the optical system 150 of the third embodiment, the second image non-generating light IG2 is combined with the combined light obtained by combining the first image non-generating light IR2 and the third image non-generating light IB2.

[0088] Even when using the light guide optical system 150A of this modified example, similar to the third embodiment, the light utilization efficiency of the illumination light LW emitted from the light source 10 can be increased by recycling the non-image generating light that is not used for image generation as illumination light LW.

[0089] (Fourth embodiment) Next, a projector according to a fourth embodiment of the present invention will be described. The basic configuration of the projector according to the fourth embodiment is the same as that of the first embodiment, but the configuration of the light modulation unit differs from that of the first embodiment. Therefore, the configuration of the light modulation unit will be mainly described below, and the same reference numerals will be used for components that are common with the drawings used in the above embodiments, and their descriptions will be omitted.

[0090] Figure 6 is a schematic diagram showing the configuration of the projector 4 in the fourth embodiment. As shown in Figure 6, the projector 4 comprises a light source 10, a photosynthesis element 20, a deflection element 25, a light modulation unit 130, a light separation unit 40, a light guide optical system 50, a first optical system 60, a diffusion element 62, a second optical system 63, a first lens array 64, a second lens array 65, a polarization conversion element 66, a superimposed lens 67, a projection optical device 70, and a relay system 140.

[0091] The light modulation unit 130 of this embodiment includes a pre-liquid crystal panel 131, a post-liquid crystal panel 132, an incident polarizer 133, and an exit polarizer 134. The pre-liquid crystal panel 131 is located on the light incident side of the light separation unit 40. The post-liquid crystal panel 132 is located on the light exit side of the light separation unit 40. In this embodiment, the pre-liquid crystal panel 131 corresponds to the "first liquid crystal panel" of the present invention, and the post-liquid crystal panel 132 corresponds to the "second liquid crystal panel" of the present invention.

[0092] The relay system 140 includes multiple relay lenses 141. The relay system 140 is configured such that the light emission surface of the image forming region of the front liquid crystal panel 131 and the light incident surface of the image forming region of the rear liquid crystal panel 132 are optically conjugate.

[0093] The front-stage liquid crystal panel 131 modulates the illumination light LW incident through the superimposed lens 67 based on image information to generate image-modulated light IL. The image-modulated light IL emitted from the front-stage liquid crystal panel 131 includes image-generating light IL1 and image-non-generating light IL2.

[0094] The image-modulated light IL emitted from the preceding liquid crystal panel 131 is incident on the light separation unit 40. The non-image generating light IL2, separated from the image modulated light IL by reflection in the light separation unit 40, enters the light guide optical system 50 and is combined with the illumination light LW emitted from the light source 10 in the photosynthesis element 20.

[0095] Meanwhile, the image generation light IL1, separated from the image modulation light IL by passing through the light separation unit 40, is incident on the incident polarizer 133 via the relay system 140. The polarization direction of the image generation light IL1 that has passed through the light separation unit 40 coincides with the direction along the light transmission axis of the incident polarizer 133. Therefore, the image generation light IL1 passes through the incident polarizer 133 and is efficiently incident on the subsequent liquid crystal panel 132. The exit polarizer 134 is positioned on the light exit side of the subsequent liquid crystal panel 132, and the light transmission axis of the exit polarizer 134 is perpendicular to the light transmission axis of the incident polarizer 133.

[0096] The image generation light IL1, separated from the image modulation light IL in the light separation unit 40, is incident on the downstream liquid crystal panel 132. The downstream liquid crystal panel 132 modulates the image generation light IL1 based on image information to generate image light. The image light modulated by the downstream liquid crystal panel 132 is incident on the projection optical device 70 via the output polarizer 134 and is magnified and projected toward the screen SCR. In this embodiment, it is preferable that the downstream liquid crystal panel 132 has a number of pixels equal to or greater than that of the upstream liquid crystal panel 131. With this configuration, it is possible to increase the light utilization efficiency of the illumination light LW while keeping costs down compared to using two high-resolution liquid crystal panels.

[0097] Thus, in this embodiment, the projector 4 recycles the non-image generating light IL2, which is not used for image generation, as illumination light LW in the light modulation unit 130 using two liquid crystal panels, thereby increasing the light utilization efficiency of the illumination light LW emitted from the light source 10. Furthermore, in the projector 4 of this embodiment, since the image-non-generating light IL2 is separated from the image-modulating light IL without light diffraction, the device configuration can be made smaller and costs reduced compared to when a conventional spatial light modulator is used. In addition, since diffraction loss due to zero-order light and higher-order diffraction patterns does not occur because light diffraction is not utilized, the light utilization efficiency can be greatly increased.

[0098] (Fifth embodiment) Next, a projector according to the fifth embodiment of the present invention will be described. The basic configuration of the projector according to the fifth embodiment is the same as that of the fourth embodiment. The difference between the fifth embodiment and the fourth embodiment is that the light modulation unit has three liquid crystal panels, and the configuration of the light separation unit is the first modified example shown in Figure 2, but the other basic configurations are the same. Therefore, the following will mainly describe the light modulation unit, the light separation unit and their peripheral configurations, and components common to the drawings used in the above embodiments will be denoted by the same reference numerals and their descriptions will be omitted.

[0099] Figure 7 is a schematic diagram showing the configuration of the projector 5 in the fifth embodiment. As shown in Figure 7, the projector 5 comprises a light source 10, a photosynthesis element 220, a light modulation unit, a light separation unit 240, a light guide optical system 250, a first optical system 60, a diffusion element 62, a second optical system 63, a first lens array 64, a second lens array 65, a polarization conversion element 66, a superimposed lens 67, a projection optical device 70, a color separation optical system 115, a synthesis optical system 6, and folding mirrors 16, 17.

[0100] In the projector 5 of this embodiment, the light source 10 simultaneously emits red light LR, green light LG, and blue light LB. In other words, the light source 10 emits white light as illumination light LW.

[0101] The photosynthetic element 220 includes a first synthesis element 221 and a second synthesis element 222. The first combining element 221 is a polarized beam splitter that transmits illumination light LW emitted from the light source 10, reflects the third image non-generating light IB2 which is separated from the third image modulated light IB by the third light separation unit 240B (described later) and guided by the light guide optical system 250, and combines the illumination light LW and the third image non-generating light IB2. The second combining element 222 is a polarizing beam splitter that combines the first non-image generating light IR2 and the second non-image generating light IG2 guided by the light guiding optical system 250, and the illumination light LW and the third non-image generating light IB2 incident from the first combining element 221, and emits them toward the light modulation section. In this embodiment, a polarization conversion element 223 is positioned between the first combining element 221 and the second combining element 222 to align the polarization direction of the light incident from the first combining element 221 with the S polarization for the second combining element 222.

[0102] The optical modulation unit of this embodiment includes a first optical modulation unit 230R, a second optical modulation unit 230G, and a third optical modulation unit 230B. The first optical modulation unit 230R modulates the red light R of the illumination light LW to generate a first image modulation light IR corresponding to the red light R. The second optical modulation unit 230G modulates the green light G of the illumination light LW to generate a second image modulation light IG corresponding to the green light G. The third optical modulation unit 230B modulates the blue light B of the illumination light LW to generate a third image modulation light IB corresponding to the blue light B.

[0103] The color separation optical system 115 separates the white illumination light LW emitted from the light source 10 into red light R, green light G, and blue light B. The color separation optical system 115 includes a first dichroic mirror 151 and a second dichroic mirror 152.

[0104] The first dichroic mirror 151 separates the illumination light LW from the light source 10 into red light R, green light G, and blue light B. The first dichroic mirror 151 transmits the red light R and reflects the green light G and blue light B. On the other hand, the second dichroic mirror 152 separates the green light G and blue light B by reflecting the green light G and transmitting the blue light B.

[0105] The first optical modulation unit 230R includes a pre-stage liquid crystal panel 231R, a post-stage liquid crystal panel 232R, an incident polarizer 233R, and an exit polarizer 234R. The second optical modulation unit 230G includes a pre-liquid crystal panel 231G, a post-liquid crystal panel 232G, an incident polarizer 233G, and an exit polarizer 234G. The third optical modulation unit 230B includes a pre-liquid crystal panel 231B, a post-liquid crystal panel 232B, an incident polarizer 233B, and an exit polarizer 234B.

[0106] The front-stage liquid crystal panel 231R modulates the red light R incident on it through the superimposed lens 67 based on image information to generate image-modulated light IR. The image-modulated light IR emitted from the front-stage liquid crystal panel 231R includes a first image-generating light IR1 and a first image-non-generating light IR2. The second optical modulation unit 230G and the third optical modulation unit 230B have the same configuration as the first optical modulation unit 230R, so their description is omitted.

[0107] The light separation unit 240 includes a first light separation unit 240R, a second light separation unit 240G, and a third light separation unit 240B. The first light separation unit 240R separates the first image modulation light IR incident from the preceding liquid crystal panel 231R of the first light modulation unit 230R into the first image generation light IR1 and the first image non-generation light IR2. The second light separation unit 240G separates the second image modulation light IG incident from the preceding liquid crystal panel 231G of the second light modulation unit 230G into the second image generation light IG1 and the second image non-generation light IG2. The third light separation unit 240B separates the third image modulation light IB, which is incident from the liquid crystal panel 231B preceding the third light modulation unit 230B, into the third image generation light IB1 and the third image non-generation light IB2.

[0108] The first light separation unit 240R includes a polarization separation element 241R, a phase difference element 242R, and a reflecting element 243R. The polarization separation element 241R is composed of a polarization beam splitter that reflects the first image generation light IR1 incident as S-polarized light and transmits the first image non-generation light IR2 incident as P-polarized light.

[0109] The first non-image generating light IR2 that has passed through the polarization separation element 241R is incident on the phase difference element 242R. The phase difference element 242R is composed of a quarter-wave plate. Therefore, the P-polarized non-image generating light IR2 that passes through the polarization separation element 241R is converted, for example, to right-handed circularly polarized non-image generating light before being incident on the reflecting element 243R. The right-handed circularly polarized non-image generating light is reflected by the reflecting element 243R as left-handed circularly polarized light.

[0110] Left-handed circularly polarized non-image generating light is converted to S-polarized non-image generating light IR2 by the phase difference element 242R. The S-polarized non-image generating light IR2 is reflected by the polarization separation element 241R and incident on the optical guide optical system 250.

[0111] The light guide optical system 250 includes a first light guide mirror 251, a second light guide mirror 252, a third light guide mirror 253, and a fourth light guide mirror 254. The first light guide mirror 251 is a mirror that reflects the first non-image generating light IR2 separated in the first light separation unit 240R toward the second light guide mirror 252. The second light guide mirror 252 is a dichroic mirror that transmits the first non-image generating light IR2 incident from the first light guide mirror 251 and reflects the second non-image generating light IG2 separated in the second light separation unit 240G toward the third light guide mirror 253, thereby synthesizing the first non-image generating light IR2 and the second non-image generating light IG2. The third light guide mirror 253 is a mirror that reflects the first non-image generating light IR2 and the second non-image generating light IG2 incident from the second light guide mirror 252 toward the second synthesis element 222 of the photosynthesis element 220. The fourth light guide mirror 254 is a mirror that reflects the third non-image generating light IB2, which has been separated in the third light separation unit 240B, toward the first synthesis element 221.

[0112] In this embodiment, a phase difference plate 224 is arranged between the second light guide mirror 252 and the third light guide mirror 253, the phase difference plate 224 being a 1 / 2 phase difference element that converts the first non-image generating light IR2 and the second non-image generating light IG2 into P-polarized light for the second combining element 222. In this embodiment, the relay optical system 51 shown in Figure 1 may be placed between the fourth light guide mirror 254 and the first combining element 221.

[0113] The second light separation unit 240G includes a polarization separation element 241G, a phase difference element 242G, and a reflecting element 243G, while the third light separation unit 240B includes a polarization separation element 241B, a phase difference element 242B, and a reflecting element 243B. Since the second light separation unit 240G and the third light separation unit 240B have the same configuration as the first light separation unit 240R, a detailed explanation is omitted.

[0114] In this way, the non-generating light IR2 of the first image is incident on the photosynthetic element 220 by the light guide optical system 250 and is combined with the illumination light LW emitted from the light source 10. Similarly, the non-generating light IG2 of the second image and the non-generating light IB2 of the third image are incident on the photosynthetic element 220 by the light guide optical system 250 and are combined with the illumination light LW emitted from the light source 10.

[0115] The first image generation light IR1, separated from the first image modulation light IR by reflection from the polarization separation element 241R, enters the incident polarizer 233R via the field lens 68R. The polarization direction of the image generation light IR1 that has passed through the polarization separation element 241R of the first light separation unit 240R coincides with the direction along the light transmission axis of the incident polarizer 233R. Therefore, the image generation light IR1 passes through the incident polarizer 233R and enters the subsequent liquid crystal panel 232R efficiently. The exit polarizer 234R is positioned on the light exit side of the subsequent liquid crystal panel 232R, and the light transmission axis of the exit polarizer 234R is perpendicular to the light transmission axis of the incident polarizer 133.

[0116] The subsequent liquid crystal panel 232R modulates the image generation light IR1 based on image information to generate red image light. In this embodiment, the second image generation light IG1 is guided to the downstream liquid crystal panel 232G of the second optical modulation unit 230G with its optical path bent by the folding mirror 16. The downstream liquid crystal panel 232G modulates the second image generation light IG1 based on image information to generate green image light. The third image generation light IB1 is guided to the downstream liquid crystal panel 232B of the third optical modulation unit 230B with its optical path bent by the folding mirror 17. The downstream liquid crystal panel 232B modulates the third image generation light IB1 based on image information to generate blue image light.

[0117] The red image light modulated by the downstream liquid crystal panel 232R is incident on the composite optical system 6 via the output polarizer 234R. Similarly, the second image generation light IG1 and the third image generation light IB1 from the second light modulation unit 230G and the third light modulation unit 230B are incident on the composite optical system 6, respectively. The composite optical system 6 emits the image light, which is a composite of the first image generation light IR1, the second image generation light IG1, and the third image generation light IB1, toward the projection optical device 70.

[0118] Thus, according to the projector 5 of this embodiment, even when a structure is adopted in which each light modulation section corresponding to the three colors uses two liquid crystal panels, the non-image generating light that is not used for image generation can be recycled as illumination light LW. Therefore, the light utilization efficiency of the illumination light LW emitted from the light source 10 can be increased. Furthermore, in the projector 5 of this embodiment, since the non-image generating light is separated from the image modulation light of each color without light diffraction, the device configuration can be made smaller and costs can be reduced compared to when a conventional spatial light modulator is used. In addition, since diffraction loss due to zero-order light and higher-order diffraction patterns does not occur because light diffraction is not utilized, the light utilization efficiency can be sufficiently increased.

[0119] (Third variation) Next, a different configuration relating to the fifth embodiment will be described as the third modification. In this modification, the layout of the light source and photosynthesis element and the configuration of the light guide optical system differ from those of the fifth embodiment. Therefore, the following description will mainly focus on the configuration of the photosynthesis element and the light guide optical system, and components common to the drawings used in the above embodiments will be denoted by the same reference numerals and their descriptions will be omitted.

[0120] Figure 8 shows the main components of the modified projector 5A. As shown in Figure 8, in the projector 5A of this modified example, the light source 10 and the photosynthetic element 220 are arranged side by side along the Y-axis. The light guide optical system 250A of this modified example also includes a first light guide mirror 251, a second light guide mirror 252, a fourth light guide mirror 254, and a fifth light guide mirror 255.

[0121] In this modified example, the fourth light guide mirror 254 reflects the third non-image generating light IB2 separated in the third light separation unit 240B toward the fifth light guide mirror 255. The fifth light guide mirror 255 is positioned on the -X side of the first synthesis element 221 of the photosynthesis element 220 and is a mirror that reflects the third non-image generating light IB2 incident from the fourth light guide mirror 254 toward the first synthesis element 221.

[0122] In this modified example, the second light guide mirror 252 is positioned on the +X side of the first combining element 221, causing the first image non-generating light IR2 and the second image non-generating light IG2 to be incident on the first combining element 221.

[0123] Thus, in this modified projector 5A, the light utilization efficiency of the illumination light LW emitted from the light source 10 can be increased by recycling the non-image generating light that is not used for image generation as illumination light LW.

[0124] It should be noted that the technical scope of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. Furthermore, the specific details regarding the shape, number, arrangement, materials, etc., of each component of the light source device and projector are not limited to the above embodiment and can be modified as appropriate.

[0125] In the above embodiments and modifications, a transmissive diffuser was given as an example for the diffuser element 62, but a reflective diffuser may also be used. Furthermore, in the above embodiments and modifications, the case in which the illumination light LW emitted from the light source 10 is P-polarized to the photosynthetic element 20 was given as an example, but the illumination light LW emitted from the light source 10 may also be S-polarized to the photosynthetic element 20. In this case, the non-image generating light separated from the image modulated light in the light separation unit will be incident on the photosynthetic element 20 as P-polarized light.

[0126] In the first embodiment, the case in which the light guide optical system 50 includes a relay optical system 51 was given as an example, but instead of the relay optical system 51, a rod lens 500 shown by the dashed line in Figure 1 may be used. The rod lens 500 may be composed of either a solid structure that utilizes total internal reflection or a hollow structure that includes a space partitioned by mirrors. When such a rod lens 500 is used, the light propagates while repeatedly reflecting inside the rod lens 500, so that non-image generating light with a uniform in-plane intensity distribution can be emitted from the emission surface of the rod lens 500.

[0127] A summary of this disclosure is provided below.

[0128] (Note 1) A light source that emits illumination light, A photosynthetic element into which the illumination light emitted from the light source is incident, A light modulation unit that modulates the light incident from the photosynthetic element to generate image-modulated light, A light separation unit separates the image-modulated light incident from the light modulation unit into image-generating light used for image generation and image-non-generating light not used for image generation. A projection optical device that projects the image generation light incident from the light separation unit, A light guide optical system that guides the non-image generating light incident from the light separation unit to the photosynthetic element, A polarization conversion element is disposed in the optical path between the photosynthetic element and the light modulation unit, and aligns the polarization direction of the light incident from the photosynthetic element. Equipped with, The illumination light emitted from the light source is light with a first polarization direction relative to the photosynthetic element, The non-image generating light incident on the photosynthetic element by the light guide optical system is light with a second polarization direction perpendicular to the first polarization direction with respect to the photosynthetic element, and is combined with the illumination light incident on the photosynthetic element from the light source and then incident on the light modulation section. projector.

[0129] With this projector configuration, the non-image generating light that is not used for image generation in the light modulation section can be recycled as illumination light, thereby increasing the light utilization efficiency of the illumination light emitted from the light source. In this configuration, since non-image-generating light is separated from image-modulated light without utilizing light diffraction, the device configuration can be made smaller and costs reduced compared to using conventional spatial light modulators. Furthermore, since diffraction losses due to zero-order light and higher-order diffraction patterns do not occur, the light utilization efficiency can be significantly increased.

[0130] (Note 2) The light incident surface of the light separation unit intersects with the optical axis of the image modulated light emitted from the light modulation unit. The projector described in Appendix 1.

[0131] With this configuration, for example, by transmitting image-generating light and reflecting non-image-generating light, image-generating light and non-image-generating light can be extracted in different directions. Therefore, non-image-generating light can be effectively separated from image-modulated light.

[0132] (Note 3) The system further comprises: a first optical system disposed in the optical path between the photosynthetic element and the polarization conversion element, which collects light incident from the photosynthetic element; a diffusion element to which the light collected by the first optical system is incident; and a second optical system that parallelizes the light diffused by the diffusion element. The projector specified in Appendix 1 or Appendix 2.

[0133] With this configuration, even when coherent light is used as illumination light, the speckle noise of the illumination light can be reduced by diffusing it with a diffusion element.

[0134] (Note 4) The system further comprises a first lens array and a second lens array into which light parallelized by the second optical system is incident, and a superposition lens that superimposes the light emitted from the second lens array onto the light modulation section. The projector described in Appendix 3.

[0135] This configuration makes it possible to improve the uniformity of the illuminance distribution of the illumination light incident on the light modulation section.

[0136] (Note 5) The aforementioned light guide optical system includes a relay optical system having a plurality of relay lenses, The relay optical system causes the light emitted from the image forming region that generates the image modulated light in the light modulation section to be imaged onto the light incident surface of the first optical system. The projector described in Appendix 3 or Appendix 4.

[0137] This configuration allows non-image-generating light, emitted from the image-forming region of the light modulation unit and passing through the light separation unit and photosynthesis element, to be efficiently incident onto the first optical system.

[0138] (Note 6) The aforementioned light guide optical system includes a rod lens, A projector listed in any one of the appendices 1 through 4.

[0139] With this configuration, image-non-image-generating light with a uniform in-plane intensity distribution can be emitted from the exit surface of the rod lens by propagating while repeatedly reflecting within the rod lens.

[0140] (Note 7) The light source includes a multimode oscillating laser light-emitting element, A projector listed in any one of the appendices 1 through 6.

[0141] This configuration allows for higher output power while suppressing speckle noise compared to single-mode oscillating laser light-emitting devices.

[0142] (Note 8) The light modulation unit includes a first light modulation unit that modulates a first color of light from the illumination light incident from the photosynthetic element to generate a first image modulated light, and a second light modulation unit that modulates a second color of light in a different wavelength band from the first color of light from the illumination light incident from the photosynthetic element to generate a second image modulated light. The light separation unit includes a first light separation element that separates the first image-modulated light incident from the first light modulation unit into first image-generating light and first image-non-generating light, and a second light separation element that separates the second image-modulated light incident from the second light modulation unit into second image-generating light and second image-non-generating light. The first non-image generating light and the second non-image generating light are incident on the photosynthetic element by the light guide optical system. A projector listed in any one of the appendices 1 through 7.

[0143] This configuration allows for the recycling of non-image-generating light separated from each image-modulating light as illumination light when using two optical modulation units corresponding to the first and second color light.

[0144] (Note 9) The optical modulation unit further includes a third optical modulation unit that modulates a third color light in a different wavelength band from the first color light and the second color light among the illumination light incident from the photosynthetic element to generate a third image modulated light. The light separation unit further includes a third light separation element that separates the third image modulated light incident from the third light modulation unit into third image generating light and third image non-generating light. The aforementioned light guide optical system includes a first combining element and a second combining element, The first combining element combines the first non-image generating light incident from the first light separation element and the second non-image generating light incident from the second light separation element and guides them to the second combining element. The second synthesis element synthesizes the first non-image generating light and the second non-image generating light incident from the first synthesis element and the third non-image generating light incident from the third light separation element and guides them to the photosynthesis element. The projector described in Appendix 8.

[0145] This configuration allows for the recycling of non-image-generating light separated from each image-modulating light as illumination light, even when using three light modulation units corresponding to the first, second, and third color light, respectively.

[0146] (Note 10) The optical modulation unit is composed of a micromirror type optical modulation element that generates the image-modulated light according to the orientation of a plurality of micromirrors. The light separation unit separates the image-modulated light into image-generating light and image-non-generating light by altering the emission direction of the image-modulated light incident from the light modulation unit. A projector listed in any one of the appendices 1 through 7.

[0147] This configuration makes it possible to recycle non-image generating light, which is not used for image generation, as illumination light, even when using a micromirror-type optical modulation element.

[0148] (Note 11) The light modulation unit includes a first liquid crystal panel located on the light incidence side of the light separation unit and a second liquid crystal panel located on the light emission side of the light separation unit. The first liquid crystal panel generates the image-modulated light by modulating the light incident from the photosynthetic element. The image generation light separated from the image modulation light in the light separation unit is incident on the second liquid crystal panel. A projector listed in any one of the appendices 1 through 7.

[0149] This configuration allows for increased light utilization efficiency of the illumination light emitted from the light source by recycling non-image generating light, which is not used for image generation, as illumination light in the light modulation section using two liquid crystal panels.

[0150] (Note 12) The aforementioned light separation unit is A polarization separation element that reflects one of the image-generating light and the non-image-generating light, and transmits the other, A phase difference element into which the non-image generating light is incident from the polarization separation element, The system includes a reflecting element that reflects the non-image generating light that has passed through the phase difference element toward the phase difference element, The non-image generating light, which is reflected by the reflective element and passes through the phase difference element, is separated from the image generating light by passing through the polarization separation element. A projector listed in any one of the appendices 1 through 9.

[0151] With this configuration, the polarization direction of the non-image-generating light separated by the polarization separation element can be changed by passing it through the phase difference element twice. Therefore, a configuration can be realized in the polarization separation element that separates non-image-generating light from image-generating light. [Explanation of Symbols]

[0152] 1,1A,2,3,3A,4,5,5A…Projector, 10…Light source, 20,220…Photosynthesis element, 30,35,37,130,230…Light modulation unit, 30R,230R…First light modulation unit, 30G,230G…Second light modulation unit, 30B,230B…Third light modulation unit, 31,31B,31G,31R…Liquid crystal panel, 36…Micromirror type light modulation element, 36a…Microphone Lomirror, 40, 40A, 45, 47, 147, 240… Light separation section, 40a… Light incident surface (of the light separation section), 60b1… Light incident surface (of the first optical system), 41, 241B, 241G, 241R… Polarization separation element, 42, 242B, 242G, 242R… Phase difference element, 43, 243B, 243G, 243R… Reflecting element, 47a… First light separation element, 47b… Second light separation element, 47c...Third light separation element, 50, 150, 150A, 250, 250A...Light guide optical system, 51...Relay optical system, 51a...Relay lens, 55, 221...First composite element, 56, 222...Second composite element, 60...First optical system, 62...Diffusion element, 63...Second optical system, 64...First lens array, 65...Second lens array, 66...Polarization conversion element, 67...Superimposed lens, 70...Projection Irradiation optical device, 500... rod lens, IL... image modulated light, IL1... image generating light, IL2... non-image generating light, IR... first image modulated light, IR1... first image generating light, IR2... first non-image generating light, IG... second image modulated light, IG1... second image generating light, IG2... second non-image generating light, IB... third image modulated light, IB1... third image generating light, IB2... third non-image generating light, LW... illumination light.

Claims

1. A light source that emits illumination light, A photosynthetic element into which the illumination light emitted from the light source is incident, A light modulation unit that modulates the light incident from the photosynthetic element to generate image-modulated light, A light separation unit separates the image-modulated light incident from the light modulation unit into image-generating light used for image generation and image-non-generating light not used for image generation. A projection optical device that projects the image generation light incident from the light separation unit, A light guide optical system that guides the non-image generating light incident from the light separation unit to the photosynthetic element, A polarization conversion element is disposed in the optical path between the photosynthetic element and the light modulation unit, and aligns the polarization direction of the light incident from the photosynthetic element. Equipped with, The illumination light emitted from the light source is light with a first polarization direction relative to the photosynthetic element. The non-image generating light incident on the photosynthetic element by the light guide optical system is light with a second polarization direction perpendicular to the first polarization direction for the photosynthetic element, and is combined with the illumination light incident on the photosynthetic element from the light source and then incident on the light modulation section. projector.

2. The light incident surface of the light separation unit intersects with the optical axis of the image modulated light emitted from the light modulation unit. The projector according to claim 1.

3. The system further comprises: a first optical system disposed in the optical path between the photosynthetic element and the polarization conversion element, which collects light incident from the photosynthetic element; a diffusion element to which the light collected by the first optical system is incident; and a second optical system that parallelizes the light diffused by the diffusion element. The projector according to claim 1.

4. The system further comprises a first lens array and a second lens array into which light parallelized by the second optical system is incident, and a superposition lens that superimposes the light emitted from the second lens array onto the light modulation section. The projector according to claim 3.

5. The aforementioned light guide optical system includes a relay optical system having a plurality of relay lenses, The relay optical system causes the light emitted from the image forming region that generates the image modulated light in the light modulation section to be imaged onto the light incident surface of the first optical system. The projector according to claim 3.

6. The aforementioned light guide optical system includes a rod lens, The projector according to claim 1.

7. The light source includes a multimode oscillating laser light-emitting element, The projector according to claim 1.

8. The light modulation unit includes a first light modulation unit that modulates a first color of light from the illumination light incident from the photosynthetic element to generate a first image modulated light, and a second light modulation unit that modulates a second color of light in a different wavelength band from the first color of light from the illumination light incident from the photosynthetic element to generate a second image modulated light. The light separation unit includes a first light separation element that separates the first image modulated light incident from the first light modulation unit into first image generating light and first image non-generating light, and a second light separation element that separates the second image modulated light incident from the second light modulation unit into second image generating light and second image non-generating light. The first non-image generating light and the second non-image generating light are incident on the photosynthetic element by the light guide optical system. The projector according to claim 1.

9. The optical modulation unit further includes a third optical modulation unit that modulates a third color light in a different wavelength band from the first color light and the second color light of the illumination light incident from the photosynthetic element to generate a third image modulated light. The light separation unit further includes a third light separation element that separates the third image modulated light incident from the third light modulation unit into third image generating light and third image non-generating light. The aforementioned light guide optical system includes a first combining element and a second combining element, The first combining element combines the first non-image generating light incident from the first light separation element and the second non-image generating light incident from the second light separation element and guides them to the second combining element. The second synthesis element synthesizes the first non-image generating light and the second non-image generating light incident from the first synthesis element and the third non-image generating light incident from the third light separation element and guides them to the photosynthesis element. The projector according to claim 8.

10. The optical modulation unit is composed of a micromirror type optical modulation element that generates the image-modulated light according to the orientation of a plurality of micromirrors. The light separation unit separates the image-modulated light into image-generating light and image-non-generating light by changing the emission direction of the image-modulated light incident from the light modulation unit. The projector according to claim 1.

11. The light modulation unit includes a first liquid crystal panel located on the light incidence side of the light separation unit and a second liquid crystal panel located on the light emission side of the light separation unit. The first liquid crystal panel generates the image-modulated light by modulating the light incident from the photosynthetic element. The image generation light separated from the image modulation light in the light separation unit is incident on the second liquid crystal panel. The projector according to claim 1.

12. The aforementioned light separation unit is A polarization separation element that reflects one of the image-generating light and the non-image-generating light, and transmits the other, A phase difference element into which the non-image generating light is incident from the polarization separation element, The system includes a reflecting element that reflects the non-image generating light that has passed through the phase difference element toward the phase difference element, The non-image generating light, which is reflected by the reflective element and passes through the phase difference element, is separated from the image generating light by passing through the polarization separation element. The projector according to claim 1.

Images