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 including first-color light and second-color light, a photosynthesis element, a light modulation unit that modulates the light incident from the photosynthesis element to generate image-modulated light, a light separation unit that separates the image-modulated light into image-generating light and non-image-generating light, an image forming unit that modulates the image-generating light to generate image light, a projection optical device that projects the image light, a light guide optical system that guides the non-image-generating light to the photosynthesis element, and a polarization conversion element arranged on the optical path between the photosynthesis element and the light modulation unit to align the polarization direction of the light incident from the photosynthesis element. The illumination light emitted from the light source is light with a first polarization direction relative to the photosynthesis element, and the non-image-generating light incident on the photosynthesis element by the light guide optical system is light with a second polarization direction perpendicular to the first polarization direction relative to the photosynthesis element, and is combined with the illumination light in the photosynthesis element and 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 input video (for example, see 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]

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, since diffraction losses occur due to zero-order light, higher-order diffraction images, etc., there is a problem that the light utilization efficiency is reduced.

Means for Solving the Problems

[0005] Note: In the translation of the patent number in , "XX" is used to replace the last two digits of the patent number as the original text does not provide specific information for those two digits. You can replace it with the actual digits according to the specific patent number.To solve the above problems, according to a first aspect of the present invention, a light source that emits illumination light including a first color light in a first wavelength band and a second color light in a second wavelength band different from the first wavelength band; a photosynthetic element to 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; an image forming unit that modulates the image-generating light incident from the light separation unit to generate image light; and a projection unit that projects the image light incident from the image forming unit. A projector is provided, comprising an optical device, 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 disposed on 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, the image-non-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 then incident on the light modulation unit. [Brief explanation of the drawing]

[0006] [Figure 1] This is a schematic diagram showing the configuration 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 is a schematic diagram showing the configuration of the projector according to the second embodiment. [Figure 4] This diagram shows the main components of a projector in the second modified example. [Figure 5] This is a schematic diagram showing the configuration of the projector according to the third embodiment. [Figure 6] This diagram shows the main components of a projector in the third modified example. [Figure 7] This is a schematic diagram showing the configuration of the projector according to the fourth embodiment. [Figure 8] This diagram shows the main components of the projector in the fourth 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, an image forming unit 130, 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 image forming unit 130 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. Note that in Figure 1, for illustrative purposes, the image forming unit 130 is shown shifted to the -X side relative to the light separation unit 40. The light separation unit 40 and the mirror 52, which is part of the light guide optical system 50, are arranged on the second optical axis AX2. The light guide optical system 50 and the photosynthesis element 20 are arranged 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 (first color light) LR in the red wavelength band (first 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 (second color light) LG in the green wavelength band (second wavelength band) of 520 nm to 600 nm. The 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 (third color light) LB in a blue wavelength band (third wavelength band) of 420 nm to 500 nm. The blue light LB is linearly polarized light. The third collimating element 12B collimates the blue light LB emitted in a state of diverging radially from the third light-emitting element 11B.

[0015] In the projector 1 of this embodiment, since a configuration that does not use diffracted light is adopted, laser light-emitting elements with multi-mode oscillation can be used as the light-emitting elements 11R, 11G, and 11B of the light source 10. According to this configuration, compared with a laser light-emitting element with single-mode oscillation, generation of speckle noise can be suppressed while obtaining high output.

[0016] Based on such a configuration, the light source 10 is configured to emit white illumination light LW including red light LR, green light LG, and blue light LB that are composed of parallel light. The number of each of the light-emitting elements 11R, 11G, and 11B in the light source 10 is appropriately set according to the color balance required in the illumination light LW. Each color light LR, LG, and LB included in the illumination light LW emitted from the light source 10 corresponds to P-polarized light with respect to the photosynthetic element 20. That is, each color light LR, LG, and LB corresponds to an example of light in the first polarization direction with respect to the photosynthetic element 20.

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

[0018] The illumination light LW that passes through the photosynthetic element 20 is reflected by the deflection element 25, changing its direction of travel 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 focuses the light entering from the photosynthetic element 20.

[0019] The first optical system 60 includes, for example, a first lens 60a and a second lens 60b. In this embodiment, the first lens 60a and the second lens 60b are each made of convex lenses. The first optical system 60 focuses the illumination light LW and directs it onto the diffusion element 62.

[0020] The diffusion element 62 transmits 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 its diffusion surface. The diffusion element 62 is, for example, a known diffusion plate or diffusion element corresponding to colored 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] In this embodiment, the light modulation unit 30 is positioned at the location where an intermediate image is formed by the illumination light LW emitted from the light source 10. With this configuration, the illumination light LW can be efficiently incident onto the light incidence region of the light modulation unit 30.

[0028] 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 illumination light LW based on image information input from an image input device (not shown), such as a personal computer or a portable terminal device.

[0029] Based on this configuration, the liquid crystal panel 31 of this embodiment emits white image-modulated light IL. 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.

[0030] 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, and only 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.

[0031] In contrast, the projector 1 of this embodiment, as described later, recycles the non-image generating light IL2 that is not used for image generation in the light modulation unit 30 and returns it to the light modulation unit 30, thereby improving the utilization efficiency of the illumination light LW emitted from the light source 10.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] The image generating light IL1, separated by passing through the light separation unit 40, is incident on the image forming unit 130. Details of the configuration of the image forming unit 130 will be described later. The image forming unit 130 modulates the image generation light IL1 incident from the light separation unit 40 to generate color image light. The projection optical device 70 magnifies and projects the color image light incident from the image forming unit 130 toward the screen SCR, which is the projection surface. An absorbing polarizer that transmits the polarization corresponding to the image light and absorbs other changes may be provided on the light incident surface of the projection optical device 70.

[0037] 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.

[0038] 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.

[0039] 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 relative to the photosynthetic element 20. In other words, the non-image generating light IL2 corresponds to an example of light with a second polarization direction perpendicular to the first polarization direction relative to the photosynthetic element 20.

[0040] 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.

[0041] The light guide optical system 50 of this embodiment includes a relay optical system 51 having a plurality of relay lenses 51a, and a mirror 52. The 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.

[0042] 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.

[0043] 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. Alternatively, 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 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, allowing non-image generating light with a uniform in-plane intensity distribution to be emitted from the emission surface of the rod lens 500.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] A portion of the composite 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 combining the light with the illumination light and injecting it into the light modulation unit 30 is repeated. This increases the brightness of the image generating light IL1, which corresponds to the brightness gradation component included in the image modulation light IL. Therefore, as described later, the contrast ratio of the image generated by modulating the image generating light IL1 in the image forming unit 130 can be further increased.

[0048] Next, the configuration of the image forming unit 130 will be described. The image forming unit 130 includes a color separation optical system 15, a first image light modulation unit 30R, a second image light modulation unit 30G, a third image light modulation unit 30B, and a synthesis optical system 6.

[0049] The color separation optical system 15 separates the white image generating light IL1 incident from the light separation unit 40 into red image generating light (first image generating light) IL1r, green image generating light (second image generating light) IL1g, and blue image generating light (third image generating light) IL1b. 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, a third reflective mirror 8c, and a fourth reflective mirror 8d, and a first relay lens 9a, a second relay lens 9b, a third relay lens 9c, and a fourth relay lens 9d.

[0050] The first dichroic mirror 7a separates the white image-generating light IL1 into blue image-generating light IL1b and the other light, which are red image-generating light IL1r and green image-generating light IL1g. The first dichroic mirror 7a transmits the blue image-generating light IL1b and reflects the other light, which are red image-generating light IL1r and green image-generating light IL1g. On the other hand, the second dichroic mirror (color separation element) 7b reflects the green image-generating light IL1g and transmits the red image-generating light IL1r, thereby separating the other light, which are red image-generating light IL1r and green image-generating light IL1g, into red image-generating light IL1r and green image-generating light IL1g.

[0051] The first reflective mirror 8a is positioned in the optical path of the red image generating light IL1r and reflects the red image generating light IL1r that has passed through the second dichroic mirror 7b toward the first image light modulation unit 30R. The second reflective mirror 8b is positioned in the optical path of the green image generating light IL1g and reflects the green image generating light IL1g that has been reflected by the second dichroic mirror 7b toward the second image light modulation unit 30G. The third reflective mirror 8c and the fourth reflective mirror 8d are positioned in the optical path of the blue image generating light IL1b and guide the blue image generating light IL1b that has passed through the first dichroic mirror 7a toward the third image light modulation unit 30B.

[0052] The first relay lens 9a is located on the light-ingress side of the color separation optical system 15 and is positioned in the optical path of the illumination light LW. The second relay lens 9b is positioned on the light-ingress side of the second dichroic mirror 7b in the optical paths of the red image-generating light IL1r and the green image-generating light IL1g. The third relay lens 9c is positioned on the light-emission side of the first dichroic mirror 7a in the optical path of the blue image-generating light IL1b. The fourth relay lens 9d is positioned between the third reflective mirror 8c and the fourth reflective mirror 8d in the optical path of the blue image-generating light IL1b and has the function of compensating for the light loss of the blue image-generating light IL1b caused by the optical path length of the blue image-generating light IL1b being longer than the optical path lengths of the red image-generating light IL1r and the green image-generating light IL1g.

[0053] The first relay lens 9a and the second relay lens 9b are configured such that the light incident surface of the image formation region that generates image modulation light IL in the light modulation unit 30 is optically conjugate to the light incident surfaces of the first image light modulation unit 30R and the second image light modulation unit 30G. With this configuration, the color separation optical system 15 can efficiently incident the red image generation light IL1r and green image generation light IL1g, separated from the image generation light IL1, onto the light incident surfaces of the first image light modulation unit 30R and the second image light modulation unit 30G. Furthermore, the first relay lens 9a and the third relay lens 9c are configured such that the light incident surface of the image formation region that generates image modulation light IL in the light modulation unit 30 and the light incident surface of the third image light modulation unit 30B are optically conjugate. With this configuration, the color separation optical system 15 can efficiently incident the blue image generation light IL1b separated from the image generation light IL1 onto the light incident surface of the third image light modulation unit 30B.

[0054] The first image light modulation unit 30R modulates the red image generation light IL1r of the image generation light IL1 to generate image light corresponding to the red image generation light IL1r. The second image light modulation unit 30G modulates the green image generation light IL1g of the image generation light IL1 to generate image light corresponding to the green image generation light IL1g. The third image light modulation unit 30B modulates the blue image generation light IL1b of the image generation light IL1 to generate image light corresponding to the blue image generation light IL1b.

[0055] The first image light modulation unit 30R includes a red liquid crystal panel 31R, an incident polarizer 32R, and an exit polarizer 33R. The second image light modulation unit 30G includes a green liquid crystal panel 31G, an incident polarizer 32G, and an exit polarizer 33G. The third image light modulation unit 30B includes a blue liquid crystal panel 31B, an incident polarizer 32B, and an exit polarizer 33B.

[0056] Furthermore, field lenses 68R, 68G, and 68B are positioned on the incident side of the first image light modulation unit 30R, the second image light modulation unit 30G, and the third image light modulation unit 30B, respectively. The field lenses 68R, 68G, and 68B parallelize the red image generating light IL1r, green image generating light IL1g, and blue image generating light IL1b incident on the first image light modulation unit 30R, the second image light modulation unit 30G, and the third image light modulation unit 30B, respectively.

[0057] The polarization direction of the P-polarized image generating light IL1 that has passed through the polarization separation element 41 coincides with the direction along the light transmission axis of the incident polarizers 32R, 32G, and 32B. Therefore, the red image generating light IL1r, green image generating light IL1g, and blue image generating light IL1b pass through the incident polarizers 32R, 32G, and 32B, respectively, and are efficiently incident on the red liquid crystal panels 31R, 31G, and 31B. The exit polarizers 33R, 33G, and 33B are positioned on the light exit side of the red liquid crystal panels 31R, 31G, and 31B, and the light transmission axes of the exit polarizers 33R, 33G, and 33B are perpendicular to the light transmission axes of the incident polarizers 32R, 32G, and 32B, respectively.

[0058] The red liquid crystal panel 31R modulates the red image generating light IL1r incident through the field lens 68R based on image information to generate red image light (first image light) GR. The green liquid crystal panel 31G modulates the green image generating light IL1g incident through the field lens 68G based on image information to generate green image light (second image light) GG. The blue liquid crystal panel 31B modulates the blue image generating light IL1b incident through the field lens 68B based on image information to generate blue image light GB.

[0059] The red image light modulated by the first image light modulation unit 30R enters the composite optical system 6 via the exit polarizer 33R. Similarly, the green image light modulated by the second image light modulation unit 30G and the blue image light modulated by the third image light modulation unit 30B enter the composite optical system 6. The composite optical system 6 emits a color image light, which is a combination of the red, green, and blue image lights, toward the projection optical device 70. For example, a cross dichroic prism is used in the composite optical system 6.

[0060] In this embodiment, a phase difference plate 6a is provided on the incident surface of the green image light GG 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 green image light GG. As a result, the green image light GG is converted to P-polarization for the cross dichroic prism by passing through the phase difference plate 6a, while the red image light GR and blue image light GB remain S-polarization for the cross dichroic prism. Therefore, the image lights of each color, GR, GG, and GB, are well combined in the composite optical system 6 and projected onto the screen SCR by the projection optical device 70.

[0061] As described above, the projector 1 of this embodiment includes a light source 10 that emits white illumination light LW including red light LR, green light LG, and blue light LB; 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; and the image modulation light IL incident from the light modulation unit 30 is used as image generation light IL1 for image generation and as non-image generation light IL2 not for image generation. The system comprises a light separation unit 40 that separates light into two, an image forming unit 130 that modulates the image generating light IL1 incident from the light separation unit 40 to generate color image light, a projection optical device 70 that projects the image light incident from the image forming unit 130, a light guide optical system 50 that guides the non-image generating 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 with respect to the photosynthesis element 20, and the non-image generating light IL2 incident on the photosynthesis element 20 by the light guide optical system 50 is S-polarized with respect to the photosynthesis element 20, and is combined with the illumination light LW incident from the light source 10 and incident on the light modulation unit 30.

[0062] In this embodiment, the projector 1 allows the image forming unit 130 to separate the dark tone component, which is not used to generate image light, from the non-image generating light IL2 in the preceding light separation unit 40 and recycle it as illumination light LW. This improves the light utilization efficiency of the illumination light LW emitted from the light source 10. Furthermore, in this embodiment, the light modulation unit 30 modulates each of the color lights LR, LG, and LB included in the illumination light LW together, thus simplifying and miniaturizing the device configuration compared to the case where each of the color lights LR, LG, and LB is individually modulated. Therefore, the projector 1 of this embodiment enables the realization of a compact projector that projects high-quality images with high light utilization efficiency and a high contrast ratio.

[0063] In the projector 1 of this embodiment, instead of using the diffraction of light, a light separation unit 40 is employed that separates the image-modulating light IL from the image-non-generating light IL2 by utilizing the difference in polarization direction. 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. 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.

[0064] (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.

[0065] 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 image forming unit 130, modulated into image light by the image forming unit 130, and projected onto the screen SCR by the projection optical device 70.

[0066] 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.

[0067] 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.

[0068] In this modified example, since the non-image generating light IL3 is incident on the optical guide optics 50 as P-polarized light, a 1 / 2 phase difference plate 44 placed in the optical path of the optical guide optics 50 converts the non-image generating light IL3 into S-polarized light for the photosynthesis element 20. This makes it possible for the non-image generating light IL3 to be combined with the illumination light LW emitted from the light source 10 in the photosynthesis element 20.

[0069] According to the projector 1A of this modified example, even when using an optical separation unit 40A with a different configuration from the first embodiment, the image-non-generating light IL3 corresponding to the dark tone component not used for image generation is recycled as illumination light LW, similar to the first embodiment. This improves the light utilization efficiency of the illumination light LW emitted from the light source 10. Therefore, the projector 1A of this modified example makes it possible to realize a compact projector that projects high-quality images with high light utilization efficiency and a high contrast ratio.

[0070] (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 image forming unit differs from that of the first embodiment. Therefore, the following description will mainly focus on the configuration of the image forming 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.

[0071] 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 of this embodiment includes a light source 10, a photosynthesis element 20, a deflection element 25, a light modulation unit 30, a light separation unit 40, an image forming unit 230, 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.

[0072] 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, and a fourth optical axis AX4. The light source 10, photosynthesis element 20, and deflection element 25 are arranged on the first optical axis AX1. The deflection element 25, first optical system 60, diffusion element 62, second optical system 63, first lens array 64, second lens array 65, polarization conversion element 66, superimposed lens 67, light separation unit 40, and image forming unit 230 are arranged on the fourth optical axis AX4. The image forming unit 230 and 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.

[0073] The light source 10 of this embodiment emits parallel light, consisting of red light LR, green light LG, and blue light LB, as illumination light LW in time sequence. Therefore, the light modulation unit 30 of this embodiment modulates the respective colored lights LR, LG, and LB that are incident sequentially as illumination light LW, and emits blue, green, or red image-modulated light IL in a time-division manner.

[0074] The image forming unit 230 of this embodiment includes a total reflection prism unit 231, a light modulation element 232, and a relay lens 233. The total internal reflection prism section 231 is composed of a prism group consisting of two prisms arranged opposite each other with a layer of air of a certain thickness in between, and has a reflective surface 231r. The angle of the reflective surface 231r is set so as to totally reflect the image generating light IL1 incident from the light separation section 40 via the relay lens 233 toward the light modulation element 232.

[0075] The optical modulation element 232 of this embodiment is composed of a micromirror type optical modulation element. The optical modulation element 232 of this embodiment is composed of, for example, a digital micromirror device (DMD) and has a plurality of micromirrors 232a arranged in a matrix. The DMD generates image light according to the orientation of the plurality of micromirrors 232a. Specifically, the DMD generates image light by switching the tilt direction of each of the plurality of micromirrors 232a. In this embodiment, the DMD is configured to generate image light of a color corresponding to the image generation light IL1 incident from the optical separation unit 40 in a time-division manner. The DMD reflects the image light in a direction along the illumination optical axis AX that passes through the reflective surface 231r of the total reflection prism unit 231.

[0076] The relay lens 233 is configured such that the light incident surface of the image forming region that generates image modulation light IL in the light modulation unit 30 is optically conjugate to each mirror surface of the light modulation element 232, which is the light incident surface of the image forming unit 230. With this configuration, the image forming unit 230 can efficiently incident the image generation light IL1 onto each mirror surface of the light modulation element 232.

[0077] The image light G emitted from the total internal reflection prism section 231 along the illumination optical axis AX enters the projection optical device 70 and is magnified and projected toward the screen SCR.

[0078] Thus, according to the projector 2 of this embodiment, even when an optical modulation element 232 composed of a DMD is used as the image forming unit 230, the non-image generating light IL2 corresponding to the dark tone component 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. Accordingly, according to the projector 2 of this embodiment, a compact projector that projects high-quality images with high light utilization efficiency and a high contrast ratio can be realized.

[0079] Furthermore, in the projector 2 of this embodiment, instead of using light diffraction, a configuration is adopted that separates 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 40. 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.

[0080] (Second variation) Next, a different configuration relating to the second embodiment will be described as a second modification. In this modification, the configuration of the light separation unit differs from that of the second embodiment. Therefore, the peripheral configuration of the light separation unit will be mainly described below, and the same reference numerals will be used for components common to the drawings used in the above embodiment, and their descriptions will be omitted.

[0081] Figure 4 shows the main components of projector 2A in this modified example. As shown in Figure 4, the optical separation unit of the projector 2A in this modified example has the optical separation unit 40A shown in Figure 2.

[0082] According to the projector 2A of this modified example, even when using an optical separation unit 40A with a different configuration from that of the second embodiment, the non-image generating light IL3, which corresponds to the dark tone component not used for image generation, is recycled as illumination light LW, similar to the case of the second embodiment. This improves the light utilization efficiency of the illumination light LW emitted from the light source 10. Therefore, the projector 2A of this modified example makes it possible to realize a compact projector that projects high-quality images with high light utilization efficiency and a high contrast ratio.

[0083] (Third embodiment) Next, a projector according to a third embodiment of the present invention will be described. The basic configuration of the projector according to the third embodiment is the same as that of the first embodiment, but the configuration of the image forming unit differs from that of the other embodiments described above. Therefore, the following description will mainly focus on the configuration of the image forming unit, 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.

[0084] Figure 5 is a schematic diagram showing the configuration of the projector 3 in the third embodiment. As shown in Figure 5, the projector 3 of this embodiment includes a light source 10, a photosynthesis element 20, a deflection element 25, a light modulation unit 30, a light separation unit 40, an image forming unit 330, 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.

[0085] The projector 3 of this embodiment has an illumination optical axis AX, a first optical axis AX1, a second optical axis AX2, a third optical axis AX3, and a fourth optical axis AX4. 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 separation unit 40, and the image forming unit 330 are arranged on the fourth optical axis AX4. The image forming unit 330 and the projection optical device 70 are arranged on the illumination optical axis AX, which intersects the fourth optical axis AX4 at an oblique angle.

[0086] The image forming unit 330 of this embodiment includes a composite prism 340, a first optical modulation element 331, a second optical modulation element 332, a third optical modulation element 333, and a relay lens 334.

[0087] The first optical modulator 331 is a micromirror type optical modulator, and is composed of, for example, a digital micromirror device (DMD). The first optical modulator 331 has a plurality of micromirrors 331a arranged in a matrix. The first optical modulator 331 generates image light according to the orientation of the plurality of micromirrors 331a. As described later, the first optical modulator 331 modulates the color-separated red image generating light (first image generating light) IL1r by the composite prism 340 according to the orientation of the plurality of micromirrors 331a to generate red image light GR.

[0088] The second optical modulator 332 is a micromirror type optical modulator, and is composed of, for example, a digital micromirror device (DMD). The second optical modulator 332 has a plurality of micromirrors 332a arranged in a matrix. The second optical modulator 332 generates image light according to the orientation of the plurality of micromirrors 232a. As described later, the second optical modulator 332 modulates the green image generating light (second image generating light) IL1g, which is color-separated by the composite prism 340, according to the orientation of the plurality of micromirrors 332a, and generates green image light GG.

[0089] The third optical modulator 333 is a micromirror type optical modulator, and is composed of, for example, a digital micromirror device (DMD). The third optical modulator 333 has a plurality of micromirrors 333a arranged in a matrix. The third optical modulator 333 generates image light according to the orientation of the plurality of micromirrors 333a. As described later, the third optical modulator 333 modulates the color-separated red image generating light IL1r by the composite prism 340 according to the orientation of the plurality of micromirrors 333a to generate red image light GR.

[0090] The relay lens 334 is configured such that the light incident surface of the image forming region that generates image modulation light IL in the light modulation unit 30 is optically conjugate to the mirror surfaces of each light modulation element 331, 332, and 333, which are the light incident surfaces of the image forming unit 330. With this configuration, the image forming unit 330 can efficiently incident the image generation light IL1 onto each mirror surface of the light modulation element 232.

[0091] The composite prism 340 has a color separation function that distributes the image generation light IL1 incident from the light separation unit 40 to the first light modulation element 331, the second light modulation element 332, and the third light modulation element 333 described above, and a photosynthesis function that combines the image lights GR, GG, and GB of each color emitted from the first light modulation element 331, the second light modulation element 332, and the third light modulation element 333 and emits them toward the projection optical device 70.

[0092] The composite prism 340 is composed of a first prism 341, a second prism 342, a third prism 343, a fourth prism 344, and a fifth prism 345. The composite prism 340 has a first reflective surface 351, a second reflective surface 352, a third reflective surface 353, and a fourth reflective surface 354.

[0093] The first prism 341, the second prism 342, the third prism 343, and the fourth prism 344 are triangular prisms with a triangular cross-section. The fifth prism 345 is a square prism with a square cross-section.

[0094] The first reflective surface 351 is composed of an air layer of a certain thickness provided at the interface between the first prism 341 and the second prism 342. The second reflective surface 352 is composed of an air layer of a certain thickness provided at the interface between the first prism 341 and the third prism 343. The third reflective surface 353 is composed of a dichroic mirror provided at the interface between the third prism 343 and the fourth prism 344. The dichroic mirror constituting the third reflective surface 353 has optical properties that reflect light in the blue wavelength band and transmit light in the green wavelength band. Furthermore, the dichroic mirror constituting the third reflective surface 353 has an incident angle dependence with respect to light in the red wavelength band, and has optical properties that transmit light in the red wavelength band incident at an incident angle smaller than a predetermined angle and reflect light in the red wavelength band incident at an incident angle larger than a predetermined angle. The fourth reflective surface 354 is composed of a dichroic mirror provided at the interface between the fourth prism 344 and the fifth prism 345. The dichroic mirror constituting the fourth reflective surface 354 has optical properties that transmit light in the green wavelength band and reflect light in the red wavelength band.

[0095] The first prism 341 has an incident light surface 341a into which the image generating light IL1 is incident. The image-generating light IL1, which enters the interior of the first prism 341 from the light incident surface 341a, is totally reflected by the first reflecting surface 351 and enters the second reflecting surface 352. In this embodiment, the image-generating light IL1 is incident on the second reflecting surface 352 at an angle smaller than the critical angle. Therefore, the image-generating light IL1 passes through the second reflecting surface 352 and enters the third prism 343, and enters the third reflecting surface 353.

[0096] In this embodiment, since the light source 10 emits white illumination light LW, the image generation light IL1 contains red, green, and blue components. Therefore, the third reflective surface 353 reflects the blue image generation light IL1b of the image generation light IL1 and transmits the other color components of the image generation light IL1, namely the green image generation light IL1g and the red image generation light IL1r.

[0097] The blue image generating light IL1b reflected by the third reflective surface 353 is totally reflected by the second reflective surface 352 and incident on the third optical modulator 333. The third optical modulator 333 modulates the blue image generating light IL1b based on image information to generate blue image light GB. The image light GB is incident on the interior of the third prism 343 from the light incident surface 343a of the third prism 343, totally reflected by the second reflective surface 352, and incident on the third reflective surface 353. The third reflective surface 353 reflects the image light GB and travels along the illumination optical axis AX. As a result, the image light GB reflected by the third reflective surface 353 passes through the third prism 343, the second reflective surface 352, the first prism 341, the first reflective surface 351, and the second prism 342, and is emitted from the composite prism 340.

[0098] The green image generating light IL1g and red image generating light IL1r that have passed through the third reflective surface 353 pass through the inside of the fourth prism 344 and are incident on the fourth reflective surface 354. The fourth reflective surface 354 transmits the green image generating light IL1g and reflects the red image generating light IL1r.

[0099] The green image generating light IL1g that has passed through the fourth reflective surface 354 passes through the fifth prism 345 and is incident on the second optical modulator 332. The second optical modulator 332 modulates the green image generating light IL1g based on the image information and generates green image light GG. The image light GG is incident on the interior of the fifth prism 345 from the light incident surface 345a of the fifth prism 345 and travels along the illumination optical axis AX. As a result, the image light GG passes through the fifth prism 345, the fourth reflective surface 354, the fourth prism 344, the third reflective surface 353, the third prism 343, the second reflective surface 352, the first prism 341, the first reflective surface 351, and the second prism 342, and is emitted from the composite prism 340.

[0100] The red image generating light IL1r reflected by the fourth reflective surface 354 travels through the inside of the fourth prism 344 and is incident on the third reflective surface 353. In this embodiment, the red image generating light IL1r reflected by the fourth reflective surface 354 is incident on the third reflective surface 353 at an incident angle greater than a predetermined angle. Therefore, the third reflective surface 353 reflects the red image generating light IL1r. The red image generating light IL1r reflected by the third reflective surface 353 passes through the fourth prism 344 and is incident on the first optical modulation element 331.

[0101] The first optical modulation element 331 modulates the red image generation light IL1r based on image information to generate the red image light GR. The image light GR travels through the interior of the fourth prism 344 from the light incident surface 344a of the fourth prism 344 and is incident on the third reflection surface 353 again. In this embodiment, the image light GR is incident on the third reflection surface 353 at an incident angle greater than a predetermined angle. Therefore, the image light GR is reflected by the third reflection surface 353, travels through the interior of the fourth prism 344, and is incident on the fourth reflection surface 354. The image light GR is reflected by the fourth reflection surface 354, travels through the interior of the fourth prism 344, and is incident on the third reflection surface 353 at an incident angle smaller than a predetermined angle. The image light GR passes through the third reflection surface 353 and travels along the illumination optical axis AX. As a result, the image light GR passes through the third prism 343, the second reflective surface 352, the first prism 341, the first reflective surface 351, and the second prism 342, and is emitted from the composite prism 340.

[0102] In this way, the image lights GR, GG, and GB of each color are combined and incident on the projection optical device 70, and projected onto the screen SCR as a color image.

[0103] Thus, according to the projector 3 of this embodiment, even when using three optical modulation elements 331, 332, and 333 composed of a DMD as the image forming unit 330, the non-image generating light IL2 corresponding to the dark tone component 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. Accordingly, according to the projector 3 of this embodiment, a compact projector that projects high-quality images with high light utilization efficiency and a high contrast ratio can be realized.

[0104] Furthermore, in the projector 3 of this embodiment, instead of using light diffraction, a configuration is adopted that separates the image-modulating light IL from the image-non-generating light IL2 by utilizing the difference in the direction of light emission from the light separation unit 40. 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.

[0105] (Third variation) Next, a different configuration relating to the third embodiment will be described as a third modification. In this modification, the configuration of the light separation unit differs from that of the third embodiment. Therefore, the peripheral configuration of the light separation unit 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.

[0106] Figure 6 shows the main components of projector 3A in this modified example. As shown in Figure 6, the optical separation unit of the projector 3A in this modified example has the optical separation unit 40A shown in Figure 2.

[0107] According to the projector 3A of this modified example, even when using an optical separation unit 40A with a different configuration from that of the third embodiment, the non-image generating light IL3, which corresponds to the dark tone component not used for image generation, is recycled as illumination light LW, similar to the third embodiment. This improves the light utilization efficiency of the illumination light LW emitted from the light source 10. Therefore, the projector 3A of this modified example makes it possible to realize a compact projector that projects high-quality images with high light utilization efficiency and a high contrast ratio.

[0108] (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 image forming unit differs from that of the other embodiments described above. Therefore, the following description will mainly focus on the configuration of the image forming unit, 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.

[0109] Figure 7 is a schematic diagram showing the configuration of the projector 4 in the fourth embodiment. As shown in Figure 7, the projector 4 of this embodiment includes a light source 10, a photosynthesis element 20, a deflection element 25, a light modulation unit 30, a light separation unit 40, an image forming unit 430, 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.

[0110] The projector 4 of this embodiment has an illumination optical axis AX, a first optical axis AX1, a second optical axis AX2, a third optical axis AX3, and a fourth optical axis AX4. The light source 10, photosynthesis element 20, and deflection element 25 are arranged on the first optical axis AX1. The deflection element 25, first optical system 60, diffusion element 62, second optical system 63, first lens array 64, second lens array 65, polarization conversion element 66, superimposed lens 67, light separation unit 40, and image forming unit 430 are arranged on the fourth optical axis AX4. Part of the image forming unit 430 and the projection optical device 70 are arranged on the illumination optical axis AX. The illumination optical axis AX is parallel to the fourth optical axis AX4 and spaced apart on the -Y side.

[0111] In this embodiment, the light source 10 emits red light LR and green light LG sequentially over time as illumination light LW, and also continuously emits blue light LB. Therefore, the light modulation unit 30 in this embodiment modulates the illumination light LW, which is incident with various colored lights sequentially over time, and emits image modulation light IL of different colors sequentially over time. Therefore, the light separation unit 40 in this embodiment emits image generation light IL1 corresponding to the color of the illumination light LW in a time-division manner. In this embodiment, the light separation unit 40 emits red image generation light IL1r and green image generation light IL1g in a time-division manner as image generation light IL1, and also continuously emits blue image generation light IL1b.

[0112] The image forming unit 430 of this embodiment includes a color separation element 431, a relay lens 432, a first liquid crystal panel 441, a first light-emitting polarizing plate 441a, a second liquid crystal panel 442, a second light-emitting polarizing plate 442a, an image photosynthesis element 450, a first reflective mirror 451, a second reflective mirror 452, and a phase difference plate 453.

[0113] The relay lens 432 is configured such that the light incident surface of the image forming region that generates image modulation light IL in the light modulation unit 30 is optically conjugate to the image forming regions of the first liquid crystal panel 441 and the second liquid crystal panel 442, which are the light incident surfaces of the image forming unit 430. With this configuration, the image forming unit 430 can efficiently incident the image generating light IL1 onto the image forming regions of each liquid crystal panel 441 and 442.

[0114] The color separation element 431 is composed of a dichroic mirror that separates the optical paths of the red image generation light IL1r and green image generation light IL1g from the optical path of the blue image generation light IL1b, which are incident from the light separation unit 40.

[0115] The red image generating light IL1r and the green image generating light IL1g are reflected by the color separation element 431 and head towards the first reflection mirror 451. The first reflection mirror 451 is located on the -Y side of the color separation element 431. The first reflection mirror 451 reflects the red image generating light IL1r and the green image generating light IL1g, which are incident from the +Y side in a time-division manner, toward the first liquid crystal panel 441.

[0116] The image generation light IL1 incident from the light separation unit 40 is P-polarized for the first liquid crystal panel 441. In this embodiment, the red image generation light IL1r and the green image generation light IL1g are converted to S-polarized for the first liquid crystal panel 441 by passing them through a phase difference plate 453, which is a half-wave plate placed between the color separation element 431 and the first reflection mirror 451.

[0117] The first liquid crystal panel 441 generates red image light (first image light) GR or green image light (second image light) GG in a time-division manner by modulating the red image generating light IL1r or green image generating light IL1g that is incident on it in a time-division manner based on the image information of the corresponding color. The image light GR and image light GG are transmitted through the first light-emitting polarizing plate 441a and incident on the image photosynthesis element 450.

[0118] Meanwhile, the blue image generating light IL1b passes through the color separation element 431 and heads towards the second reflection mirror 452. The second reflection mirror 452 reflects the blue image generating light IL1b incident from the -X side toward the second liquid crystal panel 442.

[0119] The second liquid crystal panel 442 generates blue image light (third image light) GB by modulating the blue image generation light IL1b, which is incident in a time-division manner, based on blue image information. The image light GB passes through the second light emission polarizer 442a and is incident on the image photosynthesis element 450.

[0120] The image photosynthesis element 450 is positioned in the region where the optical paths of the red image generating light IL1r and green image generating light IL1g emitted in time-division from the first liquid crystal panel 441 intersect with the optical path of the blue image generating light IL1b emitted from the second liquid crystal panel 442.

[0121] The image photosynthesis element 450 is, for example, a cube-shaped beam splitter and has a polarization separation film 451. The red image generating light IL1r and the green image generating light IL1g are S-polarized relative to the polarization separation film 451, and the blue image generating light IL1b is P-polarized relative to the polarization separation film 451.

[0122] Therefore, the image photosynthesis element 450 transmits the red image generating light IL1r and green image generating light IL1g, which are incident from the first liquid crystal panel 441 as P-polarized light, to the +X side, and reflects the blue image generating light IL1b, which is incident from the second liquid crystal panel 442 as S-polarized light, toward the +X side. As a result, the image photosynthesis element 450 can emit image light, which is a composite of the red image generating light IL1r and green image generating light IL1g and the blue image generating light IL1b, toward the projection optical device 70. The projection optical device 70 magnifies the image light incident from the image photosynthesis element 450 and projects it onto the screen SCR.

[0123] Thus, according to the projector 4 of this embodiment, even when using an image forming unit 430 that projects a full-color image including each of the RGB colors using two liquid crystal panels, the image-non-generating light IL2 corresponding to the dark tone component 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. Accordingly, according to the projector 4 of this embodiment, a compact projector that projects high-quality images with high light utilization efficiency and a high contrast ratio can be realized.

[0124] Furthermore, in the projector 4 of this embodiment, instead of using light diffraction, a configuration is adopted that separates the image-modulating light IL from the image-non-generating light IL2 by utilizing the difference in the direction of light emission from the light separation unit 40. 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.

[0125] (Fourth variation) Next, a different configuration relating to the fourth embodiment will be described as the fourth modified example. In this modified example, the configuration of the light separation unit differs from that of the fourth 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 embodiments will be denoted by the same reference numerals, and their descriptions will be omitted.

[0126] Figure 8 shows the main components of projector 4A in this modified example. As shown in Figure 8, the optical separation unit of the projector 4A in this modified example has the optical separation unit 40A shown in Figure 2.

[0127] According to the projector 4A of this modified example, even when using an optical separation unit 40A with a different configuration from that of the fourth embodiment, the non-image generating light IL3, which corresponds to the dark tone component not used for image generation, is recycled as illumination light LW, similar to the case of the fourth embodiment. This makes it possible to increase the light utilization efficiency of the illumination light LW emitted from the light source 10.

[0128] 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.

[0129] For example, in the above embodiments and modifications, a transmissive diffuser was given as an example of the diffuser element 62, but a reflective diffuser may also be used. Also, 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 photosynthesis 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 photosynthesis 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 photosynthesis element 20 as P-polarized light.

[0130] A summary of this disclosure is provided below.

[0131] (Note 1) A light source that emits illumination light including a first color of light in a first wavelength band and a second color of light in a second wavelength band different from the first wavelength band, 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. An image forming unit generates image light by modulating the image generation light incident from the light separation unit, A projection optical device that projects the image light incident from the image forming 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.

[0132] With this projector configuration, the dark tone component, which is not used to generate image light in the image forming section, can be separated in the light separation section preceding the image forming section and recycled as illumination light. This increases the light utilization efficiency of the illumination light emitted from the light source. Furthermore, since the light modulation section modulates each color of light contained in the illumination light together, the device configuration can be simplified and miniaturized compared to cases where a separate light modulation section is provided for each color of light. In addition, since this configuration separates non-image-generating light from the image-modulated light without using light diffraction, the device configuration can be miniaturized and costs reduced compared to cases using conventional spatial light modulators. Moreover, since diffraction losses due to zero-order light and higher-order diffraction patterns do not occur, the light utilization efficiency can be sufficiently increased.

[0133] (Note 2) The image forming unit is A color separation element separates the image generation light incident from the light separation unit into a first image generation light in the first wavelength band and a second image generation light in the second wavelength band. A first liquid crystal panel that modulates the first image generation light incident from the color separation element to generate a first image light, A second liquid crystal panel that modulates the second image generation light incident from the color separation element to generate a second image light, A combining optical system for combining the first image light and the second image light, The projector described in Appendix 1.

[0134] This configuration enables the recycling of non-image generating light, which is not used to generate image light, as illumination light in an image forming unit that includes two liquid crystal panels corresponding to the first and second color light.

[0135] (Note 3) The image forming unit includes a micromirror-type optical modulation element that generates the image modulated light according to the orientation of a plurality of micromirrors. The projector described in Appendix 1.

[0136] This configuration enables the recycling of non-image generating light, which is not used to generate image light, as illumination light in an image forming unit that includes a micromirror-type optical modulation element.

[0137] (Note 4) The image forming unit is A micromirror-type first optical modulation element generates first image light by modulating the first image generation light in the first wavelength band of the image generation light incident from the optical separation unit, A micromirror-type second optical modulation element generates a second image light by modulating the second image generation light in the second wavelength band of the image generation light incident from the optical separation unit, A combining prism that combines the first image light and the second image light, The projector described in Appendix 1.

[0138] This configuration enables the recycling of non-image-generating light, which is not used for image generation, as illumination light in an image forming unit that includes two micromirror-type optical modulation elements corresponding to the first and second color light.

[0139] (Note 5) The light source emits the first color light and the second color light in a time-division manner as illumination light, and also emits a third color light in a third wavelength band different from the first wavelength band and the second wavelength band. The light separation unit emits the first image generation light in the first wavelength band and the second image generation light in the second wavelength band in a time-resolved manner, and also emits the third image generation light in the third wavelength band. The image forming unit is A color separation element that separates the optical path of the first image generation light or the second image generation light incident from the light separation unit from the optical path of the third image generation light, A first liquid crystal panel generates first image light and second image light by modulating the first image generation light and the second image generation light that are incident on the color separation element in a time-division manner, respectively. A second liquid crystal panel that modulates the third image generation light incident from the color separation element to generate a third image light, Includes an image photosynthesis element that synthesizes light emitted from the first liquid crystal panel and the second liquid crystal panel, The projector described in Appendix 1.

[0140] This configuration enables the image forming unit, which generates full-color image light including each of the RGB colors using two liquid crystal panels, to recycle non-image generating light, which is not used for image generation, as illumination light.

[0141] (Note 6) The aforementioned light separation unit is A polarization separation element that reflects the non-image generating light and transmits the image generating light, 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, reflected by the reflective element and passing 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 2 through 5.

[0142] 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.

[0143] (Note 7) The light incident surface of the light modulation unit and the light incident surface of the image forming unit are optically conjugate. A projector listed in any one of the appendices 1 through 6.

[0144] This configuration allows the image generation light modulated in the optical modulation unit to be efficiently incident on the light incident surface of the image formation unit.

[0145] (Note 8) 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. A projector listed in any one of the appendices 1 through 7.

[0146] 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.

[0147] (Note 9) 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. A projector listed in any one of the appendices 1 through 8.

[0148] 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.

[0149] (Note 10) 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 9.

[0150] This configuration makes it possible to improve the uniformity of the illuminance distribution of the illumination light incident on the light modulation section.

[0151] (Note 11) 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 9 or Appendix 10.

[0152] 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.

[0153] (Note 12) The aforementioned light guide optical system includes a rod lens, A projector listed in any one of the appendices 1 through 11.

[0154] 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.

[0155] (Note 13) The light source includes a multimode oscillating laser light-emitting element, A projector listed in any one of the appendices 1 through 12.

[0156] This configuration allows for higher output power while suppressing speckle noise compared to single-mode oscillating laser light-emitting devices. [Explanation of symbols]

[0157] 1,1A,2,2A,3,3A,4,4A…Projector, 6…Synthetic optical system, 7b…Second dichroic mirror (color separation element), 10…Light source, 20…Photosynthesis element, 30…Light modulation unit, 31…Liquid crystal panel, 40,40A…Light separation unit, 41…Polarization separation element, 42…Phase difference element, 43…Reflective element, 50…Light guide optical system, 51…Relay optical system, 51a…Relay lens, 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 optical device, 450…Image photosynthesis element, 130,230,330,4 30...Image forming unit, 232...Optical modulation element, 331...First optical modulation element, 332...Second optical modulation element, 340...Combination prism, 431...Color separation element, 441...First liquid crystal panel, 442...Second liquid crystal panel, 500...Rod lens, GR...Image light (first image light), GG...Image light (second image light), GB...Image light (third image light), IL...Image modulation light, IL1...Image generation light, IL1r...Red image generation light (first image generation light), IL1g...Green image generation light (second image generation light), IL2,IL3...Non-image generation light, LR...Red light (first color light), LG...Green light (second color light), LB...Blue light (third color light), LW...Illumination light.

Claims

1. A light source that emits illumination light including a first color of light in a first wavelength band and a second color of light in a second wavelength band different from the first wavelength band, 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. An image forming unit generates image light by modulating the image generation light incident from the light separation unit, A projection optical device that projects the image light incident from the image forming 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 image forming unit is A color separation element separates the image generation light incident from the light separation unit into a first image generation light in the first wavelength band and a second image generation light in the second wavelength band. A first liquid crystal panel that modulates the first image generation light incident from the color separation element to generate a first image light, A second liquid crystal panel that modulates the second image generation light incident from the color separation element to generate a second image light, A combining optical system for combining the first image light and the second image light, The projector according to claim 1.

3. The image forming unit includes a micromirror-type optical modulation element that generates the image modulated light according to the orientation of a plurality of micromirrors. The projector according to claim 1.

4. The image forming unit is A micromirror-type first optical modulation element generates first image light by modulating the first image generation light in the first wavelength band of the image generation light incident from the optical separation unit, A micromirror-type second optical modulation element generates a second image light by modulating the second image generation light in the second wavelength band of the image generation light incident from the optical separation unit, A combining prism that combines the first image light and the second image light, The projector according to claim 1.

5. The light source emits the first color light and the second color light in a time-division manner as illumination light, and also emits a third color light in a third wavelength band different from the first wavelength band and the second wavelength band. The light separation unit emits the first image generation light in the first wavelength band and the second image generation light in the second wavelength band in a time-resolved manner, and also emits the third image generation light in the third wavelength band. The image forming unit is A color separation element that separates the optical path of the first image generation light or the second image generation light incident from the light separation unit from the optical path of the third image generation light, A first liquid crystal panel generates first image light and second image light by modulating the first image generation light and the second image generation light that are incident on the color separation element in a time-division manner, respectively. A second liquid crystal panel that modulates the third image generation light incident from the color separation element to generate a third image light, Includes an image photosynthesis element that synthesizes light emitted from the first liquid crystal panel and the second liquid crystal panel, The projector according to claim 1.

6. The aforementioned light separation unit is A polarization separation element that reflects the non-image generating light and transmits the image generating light, 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, reflected by the reflective element and passing through the phase difference element, is separated from the image generating light by passing through the polarization separation element. A projector according to any one of claims 2 to 5.

7. The light incident surface of the light modulation unit and the light incident surface of the image forming unit are optically conjugate. The projector according to claim 1.

8. 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.

9. 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.

10. 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 9.

11. 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 9 or claim 10.

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

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

Images