projector

Abstract

We provide projectors that can improve light utilization efficiency. [Solution] The projector of the present invention comprises a light source device that emits first light, second light, and third light in a time-division manner; a polarization separation element that separates each of the first light, second light, and third light into a first polarization and a second polarization; a first light modulation panel that modulates the first polarization of the first light, second light, and third light; a second light modulation panel that modulates the second polarization of the first light, second light, and third light; an image photosynthesis element that synthesizes the first modulated and second modulated light emitted from the first light modulation panel and the second light modulation panel; a light receiving element that receives light emitted from a third surface of the image photosynthesis element that is different from the first and second surfaces facing the first and second light modulation panels; and a projection optical device that projects light emitted from the fourth surface of the image photosynthesis element, wherein the light receiving element receives the other part of the first modulated light and the other part of the second modulated light emitted from the third surface.

Description

Technical Field

[0001] The present invention relates to a projector.

Background Art

[0002] A projector, which is an image display device, modulates light of different colors emitted from a light source according to image information by a light modulation device, synthesizes the modulated image light of a plurality of colors, projects it onto a screen by a projection optical device, and displays an image or video on the screen.

[0003] For example, Patent Document 1 discloses a projector that divides white light into colored lights, modulates them into image lights, and then synthesizes and projects them onto each other. In this projector, white light emitted from a light source lamp or the like passes through various optical systems including a polarization conversion element and is separated into green light, red light, and blue light by a color separation optical system including a dichroic mirror. The green light is converted into green image light by a first light modulation device. The red light and the blue light are rotated by 90° in the polarization direction at an appropriate timing by a polarization switching element arranged in front of a second light modulation device in the optical path of the colored lights. Therefore, the blue image light and the red image light are switched in time division and emitted from the second light modulation device. The blue image light or the red image light emitted from the first light modulation device and the green image light emitted from the second light modulation device are synthesized by a dichroic prism and are enlarged and projected through a projection optical device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The projector disclosed in the aforementioned Patent Document 1 has a problem in that, in the two light modulation devices, components not used to generate image light are blocked by a polarizing filter provided on the emission side of the liquid crystal panel. As a result, the blocked light is not utilized, and the utilization efficiency of the light emitted from the light source is reduced. [Means for solving the problem]

[0006] To solve the above problems, according to one aspect of the present invention, a light source device that time-division emits first light in a first wavelength band, second light in a second wavelength band different from the first wavelength band, and third light in a third wavelength band different from the first and second wavelength bands; a polarization separation element that separates each of the first light, second light, and third light emitted from the light source device into a first polarization and a second polarization having a polarization direction different from the first polarization; a first light modulation panel that modulates the first polarization of the first light, second light, and third light incident from the polarization separation element; and a second light modulation panel that modulates the second polarization of the first light, second light, and third light incident from the polarization separation element. A projector is provided, comprising: a panel; an image photosynthesis element that generates image light by combining a portion of first modulated light emitted from the first light modulation panel and a portion of second modulated light emitted from the second light modulation panel; a light receiving element of the image photosynthesis element that receives light emitted from a third surface different from the first surface facing the first light modulation panel and the second surface facing the second light modulation panel; and a projection optical device that projects image light emitted from a fourth surface of the image photosynthesis element different from the first, second, and third surfaces, wherein the third surface of the image photosynthesis element emits the remaining portion of the first modulated light and the remaining portion of the second modulated light toward the light receiving element. [Brief explanation of the drawing]

[0007] [Figure 1] This is a plan view showing the schematic configuration of the projector according to the first embodiment. [Figure 2] This figure shows the behavior of light emitted from the first and second optical modulation panels. [Figure 3] This is an illustrative diagram showing the correspondence between the detected light and the image light. [Figure 4] This is the main part of the projector according to the second embodiment. [Figure 5] This is a plan view showing the configuration of the polarization conversion unit. [Figure 6A] This figure shows the behavior of light in the second state of the polarization conversion section. [Figure 6B] This figure shows the behavior of light in the third state of the polarization conversion section. [Figure 7A] This figure shows the non-rotating state of the polarization conversion unit of the third embodiment. [Figure 7B] This figure shows the first rotation state of the polarization conversion unit of the third embodiment. [Figure 7C] This figure shows the second rotation state of the polarization conversion unit of the third embodiment. [Figure 8A] This diagram shows the main components of the first modified example. [Figure 8B] This diagram shows the main components of the second modified example. [Figure 8C] This diagram shows the main components of the third modified example. [Figure 8D] This diagram shows the main components of the fourth modified example. [Modes for carrying out the invention]

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

[0009] (First Embodiment) Figure 1 is a plan view showing the schematic configuration of the projector according to this embodiment. As shown in Figure 1, the projector 100 of this embodiment includes a light source device 10, a polarization separation element 20, a first light modulation panel 30, a second light modulation panel 40, an image photosynthesis element 50, a light receiving element 60, a projection optical device 70, a first reflective mirror 81, a second reflective mirror 82, and a control device CONT.

[0010] The light source device 10 includes a first light source 11B, a second light source 11G, and a third light source 11R. The light source device 10 sequentially drives the first light source 11B, the second light source 11G, and the third light source 11R to emit blue light BL, green light GL, and red light RL in a time - division manner toward the +Z side.

[0011] In the following description, an axis parallel to the optical axis of each color light BL, GL, RL emitted from the light source device 10 in a time - division manner is defined as the X - axis. One side along the X - axis is defined as the - X side, and the side opposite to the - X side along the X - axis is defined as the +X side. Also, an axis parallel to the optical axis of the light emitted from the image light - synthesizing element 50 toward the light - receiving element 60 is defined as the Y - axis. One side along the Y - axis is defined as the - Y side, and the side opposite to the - Y side along the Y - axis is defined as the +Y side. An axis perpendicular to the X - axis and the Y - axis is defined as the Z - axis. One side on the Z - axis is defined as the - Z side, and the side opposite to the - Z side on the Z - axis is defined as the +Z side.

[0012] The first light source 11B emits blue light BL in a blue wavelength band within the visible wavelength range. The blue light BL is at least non - polarized and includes S - polarized light and P - polarized light, and for example, is random polarized light. BL[S + P] in FIG. 1 represents the blue light BL including S - polarized light and P - polarized light. The blue light BL corresponds to the first light. The blue wavelength band corresponds to the first wavelength band and is, for example, a wavelength band of 420 nm to 500 nm.

[0013] The first light source 11B is a laser diode (LD) or a light - emitting diode (LED) capable of emitting non - polarized blue light BL. When an LD that emits only S - polarized or P - polarized blue light BL is used as the first light source 11B, a plurality of LDs with different directions of the light emission ports may be used, or a phase - difference plate or a wavelength plate (not shown) may be combined.

[0014] The second light source 11G emits green light GL in a green wavelength band different from the blue wavelength band in the visible wavelength band. The green light GL is at least non-polarized, includes S-polarized light and P-polarized light, and is, for example, randomly polarized. GL[S+P] in FIG. 1 represents the green light GL including S-polarized light and P-polarized light. The green light GL corresponds to the second light. The green wavelength band corresponds to the second wavelength band and is, for example, a wavelength band of 520 nm to 600 nm. The second light source 11G is a LD or LED capable of emitting non-polarized green light GL. When a LD that emits only S-polarized or P-polarized green light GL is used as the second light source 11G, a plurality of LDs with different directions of light emission ports may be used, or a phase difference plate or wavelength plate not shown may be combined.

[0015] The third light source 11R emits red light RL in a red wavelength band different from the blue wavelength band and the green wavelength band in the visible wavelength band. The red light RL is at least non-polarized, includes S-polarized light and P-polarized light, and is, for example, randomly polarized. RL[S+P] in FIG. 1 represents the red light RL including S-polarized light and P-polarized light. The red light RL corresponds to the third light. The red wavelength band corresponds to the third wavelength band and is, for example, a wavelength band of 650 nm to 780 nm. The third light source 11R is a LD or LED capable of emitting non-polarized red light RL. When a LD that emits only S-polarized or P-polarized red light RL is used as the third light source 11R, a plurality of LDs with different directions of light emission ports may be used, or a phase difference plate or wavelength plate not shown may be combined.

[0016] The polarization separation element 20 is disposed on the +X side of the light source device 10. The polarization separation element 20 separates the S-polarized light and P-polarized light included in each of the incident blue light BL, green light GL, and red light RL, and emits the S-polarized light and P-polarized light of each color light in different directions. One of the S-polarized light and P-polarized light, the S-polarized light, corresponds to the first polarization and is represented by "S" in FIG. 1. The other of the S-polarized light and P-polarized light, the P-polarized light, corresponds to the second polarization and is represented by "P" in FIG. 1. Note that the P-polarized light may correspond to the first polarization, the S-polarized light may correspond to the second polarization, and the following-described configuration may be appropriately arranged accordingly.

[0017] The polarization separation element 20 is, for example, a cube-shaped polarization beam splitter and has a first polarization separation film 21. The first polarization separation film 21 is positioned to move from the -X side to the +X side as the beam moves from the +Y side to the -Y side, and transmits the P-polarized light of the incident blue light BL, green light GL, and red light RL, and reflects the S-polarized light of the incident blue light BL, green light GL, and red light RL. The polarization separation element 20 transmits the P-polarized light of the blue light BL, green light GL, and red light RL incident from the -X side and emits it to the +X side, and as described above, reflects the S-polarized light of the incident blue light BL, green light GL, and red light RL, and emits it to the -Y side.

[0018] The first reflective mirror 81 is positioned on the optical paths of the S-polarized blue light BL, green light GL, and red light RL emitted from the polarization separation element 20. The first reflective mirror 81 is positioned on the -X side of the polarization separation element 20. The reflective surface of the first reflective mirror 81 is positioned so that it moves from the -X side to the +X side as the movement from the +Y side to the -Y side occurs, and reflects the S-polarized blue light BL, green light GL, and red light RL. The first reflective mirror 81 reflects the S-polarized blue light BL, green light GL, and red light RL incident from the +Y side toward the first optical modulation panel 30 and emits them toward the +X side.

[0019] The second reflective mirror 82 is positioned on the optical paths of the P-polarized blue light BL, green light GL, and red light RL emitted from the polarization separation element 20. The second reflective mirror 82 is positioned on the +X side of the polarization separation element 20. The reflective surface of the second reflective mirror 82 is positioned so that it moves from the -X side to the +X side as the direction moves from the +Y side to the -Y side, and reflects the P-polarized blue light BL, green light GL, and red light RL. The second reflective mirror 82 reflects the P-polarized blue light BL, green light GL, and red light RL incident from the -X side toward the second optical modulation panel 40 and emits them toward the -Y side.

[0020] The first optical modulation panel 30 is positioned on the optical paths of the S-polarized blue light BL, green light GL, and red light RL emitted from the first reflective mirror 81. The first optical modulation panel 30 modulates the S-polarized blue light BL, green light GL, and red light RL, which are incident in a time-resolved manner, based on image information, and converts them into blue image light, green image light, and red image light.

[0021] The first optical modulation panel 30 is, for example, a transmissive liquid crystal panel. The liquid crystal panel constituting the first optical modulation panel 30 has an optical modulation surface parallel to the YZ plane. The optical modulation surface of the liquid crystal panel constituting the first optical modulation panel 30 has a rectangular shape when viewed along the X direction, and has a plurality of pixels (not shown) arranged therein. Each pixel modulates the blue light BL, green light GL, and red light RL incident from the first reflection mirror 81 based on image information, and generates the first blue image light, the first green image light, and the first red image light in a time-division manner. The first blue image light, the first green image light, and the first red image light emitted by the first optical modulation panel 30 in a time-division manner each correspond to the first modulated light.

[0022] The second optical modulation panel 40 is positioned on the optical paths of the P-polarized blue light BL, green light GL, and red light RL emitted from the second reflective mirror 82. The second optical modulation panel 40 modulates the P-polarized blue light BL, green light GL, and red light RL, which are incident in a time-resolved manner, based on image information, and converts them into blue image light, green image light, and red image light.

[0023] The second optical modulation panel 40 is, for example, a transmissive liquid crystal panel. The liquid crystal panel constituting the second optical modulation panel 40 has an optical modulation surface parallel to the XZ plane. The optical modulation surface of the liquid crystal panel constituting the second optical modulation panel 40 has a rectangular shape when viewed along the Y direction, and has a plurality of pixels (not shown) arranged therein. Each pixel modulates the blue light BL, green light GL, and red light RL incident from the second reflection mirror 82 based on image information, and generates the second blue image light, the second green image light, and the second red image light in a time-division manner. The second blue image light, the second green image light, and the second red image light emitted by the second optical modulation panel 40 in a time-division manner each correspond to the second modulated light.

[0024] The image photosynthesis element 50 is positioned in the region where the optical path of the first modulated light L1 emitted in time-resolved manner from the first optical modulation panel 30 and the optical path of the second modulated light L2 emitted in time-resolved manner from the second optical modulation panel 40 intersect.

[0025] The image photosynthesis element 50 is, for example, a cube-shaped beam splitter and has a second polarization separation membrane 51. The second polarization separation membrane 51 is positioned to move from the -X side to the +X side as the beam moves from the +Y side to the -Y side. The image photosynthesis element 50 has a first side surface (first surface) 50a, a second side surface (second surface) 50b, a third side surface (third surface) 50c, and a fourth side surface (fourth surface) 50d. The first side surface 50a is a surface that aligns with the YZ plane, and the first optical modulation panel 30 faces it, and the first modulated light L1 is incident on it. The second side surface 50b is a surface that aligns with the XZ plane, and the second optical modulation panel 40 faces it, and the second modulated light L2 is incident on it. The third side surface 50c is a surface different from the first side surface 50a and the second side surface 50b, and it intersects with the first side surface 50a and is parallel to the second side surface 50b and faces the opposite side (-Y side). The fourth side surface 50d is a surface different from all of the first to third sides surface 50a to 50c, intersects with the second side surface 50b and the third side surface 50c, and is parallel to the first side surface 50a and faces the opposite side (+X side).

[0026] Figure 2 shows the behavior of light emitted from the first optical modulation panel 30 and the second optical modulation panel 40. As shown in Figure 2, the first modulated light L1 emitted from the first optical modulation panel 30 includes first image generation light L11 used for image generation and first non-image generation light L12 not used for image generation. In other words, the first image generation light L11 corresponds to the light that constitutes the pixels for the bright tones of the image, and the first non-image generation light L12 included in the first modulated light L1 corresponds to the light that constitutes the pixels for the dark tones of the image.

[0027] Furthermore, the second modulated light L2 emitted from the second light modulation panel 40 includes a second image generation light L21 used for image generation and a second non-image generation light L22 not used for image generation. In other words, the second image generation light L21 corresponds to the light that constitutes the pixels for the bright tones of the image, and the second non-image generation light L22 included in the second modulated light L2 corresponds to the light that constitutes the pixels for the dark tones of the image.

[0028] In conventional liquid crystal panels, the image-non-generating light that constitutes the dark-tone pixels is blocked by a polarizing plate on the light-emitting side, while the image-generating light that constitutes the bright-tone pixels is transmitted, thereby projecting the desired image onto a projection surface such as a screen. Therefore, conventional liquid crystal panels have the problem of reduced utilization efficiency of the light emitted from the light source device because they do not utilize the image-non-generating light that is blocked by the polarizing plate on the emission side.

[0029] In contrast, the projector 100 of this embodiment, as described later, improves the utilization efficiency of the light emitted from the light source device 10 by receiving the first non-image generating light L12, which is not used for image generation in the first light modulation panel 30, and the second non-image generating light L22, which is not used for image generation in the second light modulation panel 40, with the light receiving element 60.

[0030] The behavior of light when the first image non-generating light L12 and the second image non-generating light L22 are incident on the photodetector 60 will be described below. The second polarization separation film 51 of the image photosynthesis element 50 separates the first modulated light L1 and the second modulated light L2 into image-generating light and non-image-generating light, respectively. The second polarization separation film 51 transmits the P-polarized light of the first modulated light L1 and the second modulated light L2, respectively, and reflects the S-polarized light of the first modulated light L1 and the second modulated light L2, respectively.

[0031] Of the first modulated light L1, the first image-generating light L11 corresponds to P-polarization for the second polarization separator 51, and of the first modulated light L1, the first non-image-generating light L12 corresponds to S-polarization for the second polarization separator 51. Furthermore, of the second modulated light L2, the second image-generating light L21 corresponds to S-polarization for the second polarization separator 51, and of the second modulated light L2, the second non-image-generating light L22 corresponds to P-polarization for the second polarization separator 51.

[0032] The image photosynthesis element 50 transmits the first image generation light L11, which is P-polarized from the first modulated light L1 incident from the first side surface 50a, toward the fourth side surface 50d, and reflects the second image generation light L21, which is S-polarized from the second modulated light L2 incident from the second side surface 50b, toward the fourth side surface 50d. As a result, the image photosynthesis element 50 can emit image light GP, which is a composite of the first image generation light L11 and the second image generation light L21, from the fourth side surface 50d. In this embodiment, the first image generation light L11 corresponds to a part of the first modulated light, and the second image generation light L21 corresponds to a part of the second modulated light.

[0033] Image light GP emitted from the fourth side surface 50d of the image photosynthesis element 50 enters the projection optical device 70. The projection optical device 70 magnifies and projects the image light GP entering from the image photosynthesis element 50 toward the screen, which is the projection surface. The projection optical device 70 is composed of, for example, one or more optical lenses. Optical lenses include, for example, plano-convex lenses, biconvex lenses, meniscus lenses, aspherical lenses, rod lenses, and free-form surface lenses.

[0034] On the other hand, the image photosynthesis element 50 reflects the first non-image generating light L12, which is S-polarized from the first modulated light L1 incident from the first side surface 50a, toward the third side surface 50c, and also reflects the second non-image generating light L22, which is P-polarized from the second modulated light L2 incident from the second side surface 50b, toward the third side surface 50c. As a result, the image photosynthesis element 50 can emit the first non-image generating light L12 and the second non-image generating light L22 from the third side surface 50c.

[0035] The light-receiving element 60 is positioned opposite the third side surface 50c of the image photosynthesis element 50. The light-receiving element 60 receives the first non-image generating light L12 and the second non-image generating light L22 emitted from the third side surface 50c of the image photosynthesis element 50 as the light to be detected PL. The light-receiving element 60 is composed of, for example, a photodetection sensor such as a photodiode.

[0036] The light-receiving element 60 is electrically connected to the control device CONT. The light-receiving element 60 transmits the detection result of the image light GP to the control device CONT. Based on the light-receiving result of the detected light PL by the light-receiving element 60, the control device CONT acquires the color balance (white balance) of the image light GP.

[0037] Here, the first non-image generating light L12 and the second non-image generating light L22, each included in the detected light PL received by the light-receiving element 60, are black and white inverted images of the first image generating light L11 and the second image generating light L21, respectively, which generate the image light GP.

[0038] Figure 3 is an illustrative diagram showing the correspondence between the detected light PL and the image light GP. As shown in Figure 3, for example, if the image light GP corresponds to an image with white "EPSON" text on a black background, the detected light PL will be a black and white inverted image with black "EPSON" text on a white background.

[0039] Since the detected light PL is a black-and-white inverted image of the image light GP, the black areas of the image light GP have the maximum received light intensity, the white areas have the minimum received light intensity, and the intermediate grayscale areas also have inverted received light intensity. Therefore, the control device CONT can calculate the actual color balance (white balance) of the image light GP by calculating the inverted intensity of the detected light PL. The control device CONT adjusts the color balance (white balance) of the image light GP to the desired balance by controlling at least one of the light source device 10, the first light modulation panel 30, and the second light modulation panel 40.

[0040] In this embodiment, the control device CONT can easily and accurately adjust the white balance of the image light GP to a desired value by individually controlling, for example, the outputs of the first light source 11B, the second light source 11G, and the third light source 11R in the light source device 10.

[0041] As described above, the projector 100 of this embodiment includes a light source device 10 that time-divisionally emits blue light BL in the blue wavelength band, green light GL in the green wavelength band, and red light RL in the red wavelength band; a polarization separation element 20 that separates the blue light BL, green light GL, and red light RL emitted from the light source device 10 into S-polarized and P-polarized light; a first light modulation panel 30 that modulates the S-polarized light of the blue light BL, green light GL, and red light RL incident from the polarization separation element 20; and a first light modulation panel 30 that modulates the P-polarized light of the blue light BL, green light GL, and red light RL incident from the polarization separation element 20. The system comprises a second optical modulation panel 40, an image photosynthesis element 50 that generates image light GP by combining a portion of the first modulation light L1 emitted from the first optical modulation panel 30 and a portion of the second modulation light L2 emitted from the second optical modulation panel 40, a light receiving element 60 that receives light emitted from a third side surface 50c of the image photosynthesis element 50, which is different from the first side surface 50a facing the first optical modulation panel 30 and the second side surface 50b facing the second optical modulation panel 40, and a projection optical device 70 that projects the image light GP emitted from the fourth side surface 50d of the image photosynthesis element 50. The third side surface 50c of the image photosynthesis element 50 emits the first non-image generating light L12 of the first modulation light L1 and the second non-image generating light L22 of the second modulation light L2 toward the light receiving element 60.

[0042] In the projector 100 of this embodiment, the light source device 10 emits three primary colored light in a time-division manner. For each colored light, the polarization separation element 20, which is located downstream of the light source device 10 and upstream of the first optical modulation panel 30 and the second optical modulation panel 40 in the optical path of the colored light, separates the colored light into two different polarizations, namely S-polarization and P-polarization. Each polarization is incident on the first optical modulation panel 30 and the second optical modulation panel 40, respectively, and the generated first image generation light L11 and second image generation light L21 of each color are combined with each other by the image photosynthesis element 50 and projected. With these configurations, instead of separating the colored light emitted from the light source device by color, as is often seen in conventional so-called three-panel and two-panel projectors, the colored light emitted from the light source device 10 is separated into two optical paths by polarization separation, and each optical path is incident on the first optical modulation panel 30 and the second optical modulation panel 40. Therefore, in the projector 100 of this embodiment, unlike conventional projectors, it is not necessary to place an incident polarizing element immediately before the optical modulation device in the optical path of the colored light, thereby reducing the halving of the brightness of the image light caused by the placement of an incident polarizing element, and suppressing the generation of colored light that is blocked as unwanted light before it is incident on the optical modulation device. Furthermore, according to the projector 100 of this embodiment, the loss of colored light in the optical path before the first optical modulation panel 30 and the second optical modulation panel 40 is suppressed, improving the light utilization efficiency, and the number of components such as the incident polarizing element that have been used in conventional projects is reduced, thus preventing an increase in size.

[0043] Furthermore, in the projector 100 of this embodiment, the first non-image generating light L12 and the second non-image generating light L22, which are included in the modulated light L1 and P2 of the first and second optical modulation panels 30 and 40, respectively and are not used for image generation, can be used as the detected light PL of the light receiving element 60. Therefore, the output-side polarizing element, which was placed downstream of the optical modulation device in conventional projectors to block light components not used for image generation, can be omitted. Thus, the projector 100 of this embodiment can significantly improve the light utilization efficiency of the light source device 10.

[0044] (Second Embodiment) A second embodiment of the projector of the present invention will be described below. The difference between this embodiment and the first embodiment lies in the peripheral configuration of the photodetector; all other configurations are common. Therefore, the following description will mainly focus on the peripheral configuration of the photodetector, with the same reference numerals used for common components, and detailed explanations will be omitted.

[0045] Figure 4 shows the peripheral configuration of the light-receiving element, which is a key part of the projector in the second embodiment. As shown in Figure 4, the projector 101 of this embodiment includes a polarization conversion unit 90 provided between the image photosynthesis element 50 and the light receiving element 60.

[0046] The polarization conversion unit 90 changes the polarization state of the detected light PL emitted from the third side surface 50c of the image photosynthesis element 50. The polarization conversion unit 90 includes a first polarizing plate 91, a second polarizing plate 92, a glass plate 93, a frame 94, and a sliding mechanism 95.

[0047] The first polarizer 91 transmits S-polarized light and reflects or absorbs P-polarized light. Therefore, the first polarizer 91 transmits the first image-non-generating light L12, which is S-polarized light from the detected light PL, and reflects or absorbs the second image-non-generating light L22, which is P-polarized light from the detected light PL.

[0048] The second polarizer 92 transmits P-polarized light and reflects or absorbs S-polarized light. Therefore, the second polarizer 92 reflects or absorbs the first image-non-generating light L12, which is S-polarized light from the detected light PL, and transmits the second image-non-generating light L22, which is P-polarized light from the detected light PL.

[0049] The glass plate 93 has the same external shape as the first polarizing plate 91 and the second polarizing plate 92. The glass plate 93 transmits incident light regardless of the polarization direction.

[0050] Figure 5 is a plan view showing the configuration of the polarization conversion unit 90. Figure 5 is a plan view of the polarization conversion unit 90 as seen from the +Y side. As shown in Figure 5, the frame 94 holds the outer surfaces of the first polarizing plate 91, the second polarizing plate 92, and the glass plate 93. Therefore, the first polarizing plate 91, the second polarizing plate 92, and the glass plate 93 held by the frame 94 are capable of transmitting light.

[0051] The slide mechanism 95 includes a rail-shaped rack gear section 95a provided on the frame 94, a pinion gear section 95b that meshes with the rack gear section 95a, and a motor device 95c that rotates the pinion gear section 95b. Based on this configuration, the slide mechanism 95 can switch between a first state in which the glass plate 93 is facing the third side surface 50c of the image photosynthesis element 50, a second state in which the first polarizing plate 91 is facing the third side surface 50c of the image photosynthesis element 50, and a third state in which the second polarizing plate 92 is facing the third side surface 50c of the image photosynthesis element 50 by moving the frame 94 along the X direction.

[0052] In the first state, the detected light PL passes through the glass plate 93, so the light-receiving element 60 detects the first non-image generating light L12 and the second non-image generating light L22 contained in the detected light PL. Therefore, in the first state, the control device CONT can detect the white balance of the image light GP, similar to the first embodiment.

[0053] Figure 6A shows the behavior of light in the second state, and Figure 6B shows the behavior of light in the third state. In the second state shown in Figure 6A, the detected light PL is incident on the first polarizer 91. As a result, the photodetector 60 receives only the first image non-generating light L12 from the detected light PL. In this way, the polarization conversion unit 90 can change the polarization state of the detected light PL received by the photodetector 60 from the first state by moving the frame 94 to the position of the second state using the slide mechanism 95. In the second state, the control device CONT can acquire information on the first image non-generating light L12, which is another part of the first modulated light L1 emitted from the first optical modulation panel 30. Therefore, the control device CONT can individually detect the white balance in the image light of the first optical modulation panel 30. Thus, by appropriately adjusting the driving conditions of the first optical modulation panel 30, white balance disturbances caused by the first optical modulation panel 30 can be well corrected.

[0054] In the third state shown in Figure 6B, the detected light PL is incident on the second polarizer 92. As a result, the photodetector 60 receives only the second image non-generating light L22 from the detected light PL. The polarization conversion unit 90 can change the polarization state of the detected light PL received by the photodetector 60 from the first and second states by moving the frame 94 to the position of the third state using the slide mechanism 95. In the third state, the control device CONT can acquire information on the second image non-generating light L22, which is the other part of the second modulated light L2 emitted from the second light modulation panel 40. Therefore, the control device CONT can individually detect the white balance in the image light of the second light modulation panel 40. Thus, by appropriately adjusting the driving conditions of the second light modulation panel 40, white balance disturbances caused by the second light modulation panel 40 can be well corrected.

[0055] According to the projector 101 of this embodiment, the polarization conversion unit 90 changes the polarization state of the light received by the light-receiving element 60, thereby allowing the information received by the light-receiving element 60 to be switched. Therefore, a projector 101 can be realized that can adjust the white balance of the image light GP with higher precision and efficiency.

[0056] (Third embodiment) A third embodiment of the projector of the present invention will be described below. The difference between this embodiment and the second embodiment lies in the configuration of the polarization conversion unit; all other components are common. Therefore, the following description will mainly focus on the configuration of the polarization conversion unit, using the same reference numerals for common components, and omitting detailed explanations.

[0057] Figures 7A to 7C show the peripheral configuration of the polarization conversion unit of the third embodiment. Figure 7A shows the non-rotating state in which the phase difference plate 191, described later, is not rotated, Figure 7B shows the configuration of the first rotating state in which the phase difference plate 191, described later, is rotated by a predetermined angle, and Figure 7C shows the configuration of the second rotating state in which the phase difference plate 191, described later, is rotated by a predetermined angle.

[0058] As shown in Figures 7A to 7C, the projector 102 of this embodiment includes a polarization conversion unit 190 provided between the image photosynthesis element 50 and the light receiving element 60. The polarization conversion unit 190 of this embodiment includes a phase difference plate 191 that is rotatably mounted at a position facing the third side surface 50c of the image photosynthesis element 50, and a third polarizing plate 192 into which light emitted from the phase difference plate 191 is incident.

[0059] The phase difference plate 191 is a rotatable half-wave plate. The third polarizer plate 192 transmits S-polarized light and reflects or absorbs P-polarized light. In the non-rotating state shown in Figure 7A, the lagging axis angle of the phase difference plate 191 is 0 degrees or 90 degrees. At this time, the detected light PL passes through the phase difference plate 191 and is incident on the third polarizer plate 192, but the phase difference plate 191 does not change the polarization state of the detected light PL. Therefore, the first image non-generating light L12 of the detected light PL passes through the third polarizer plate 192 and is incident on the photodetector 60.

[0060] In this non-rotating state, the control device CONT can individually detect the white balance in the image light of the first optical modulation panel 30 by acquiring information on the first non-image generating light L12, which is another part of the first modulated light L1 emitted from the first optical modulation panel 30. Therefore, by appropriately adjusting the driving conditions of the first optical modulation panel 30, white balance disturbances caused by the first optical modulation panel 30 can be effectively corrected.

[0061] In the first rotation state shown in Figure 7B, the lagging axis angle of the phase difference plate 191 is 45 degrees or 135 degrees. At this time, as the detected light PL passes through the phase difference plate 191, the polarization directions of the first image non-generating light L12 and the second image non-generating light L22 are rotated by 90 degrees. As a result, the first image non-generating light L12 is converted from S-polarized to P-polarized, and the second image non-generating light L22 is converted from P-polarized to S-polarized. Therefore, the second image non-generating light L22 of the detected light PL passes through the third polarizer plate 192 and is incident on the photodetector 60.

[0062] In this first rotation state, the control device CONT can individually detect the white balance in the image light of the second optical modulation panel 40 by acquiring information on the second non-image generating light L22, which is another part of the second modulated light L2 emitted from the second optical modulation panel 40. Therefore, by appropriately adjusting the driving conditions of the second optical modulation panel 40, white balance disturbances caused by the second optical modulation panel 40 can be effectively corrected.

[0063] In the second rotation state shown in Figure 7C, the lagging axis angle of the phase difference plate 191 is 22.5 degrees or 67.5 degrees. At this time, the detected light PL passes through the phase difference plate 191, and the first image non-generated light L12 and the second image non-generated light L22 are converted into circularly polarized light containing half S-polarization and half P-polarization. As a result, the S-polarized light contained in the first image non-generated light L12 and the second image non-generated light L22 passes through the third polarizer plate 192 and is incident on the photodetector 60 as the detected light PL.

[0064] In this second rotation state, the control device CONT can detect the white balance of the image light GP, similar to the first embodiment, by acquiring information on the first image non-generating light L12 and the second image non-generating light L22.

[0065] According to the projector 102 of this embodiment, the polarization state of the light received by the photodetector 60 can be changed by adjusting the rotation angle of the phase difference plate 191 in the polarization conversion unit 190, thereby easily switching the information received by the photodetector 60. Therefore, a projector 102 can be realized that can adjust the white balance of the image light GP with higher precision and efficiency.

[0066] In this embodiment, the polarization conversion unit 190 rotates the phase difference plate 191 at a position facing the third side surface 50c. However, instead of the phase difference plate 191, a polarizing plate may be rotated to selectively cause the first image non-generated light L12 or the second image non-generated light L22 to be incident on the photodetector 60. Alternatively, instead of the phase difference plate 191, a liquid crystal panel without pixels may be rotated to change the polarization direction of the first image non-generating light L12 and the second image non-generating light L22, thereby selectively transmitting the first image non-generating light L12 or the second image non-generating light L22 through the third polarizing plate 162 and causing it to incident on the photodetector 60.

[0067] (First variation) The following describes a first modified example of the projector of the present invention. Components common to this modified example and the first embodiment are denoted by the same reference numerals, and their details are omitted from further explanation. Figure 8A shows the main components of this modified example. As shown in Figure 8A, the projector 100A of this modified example includes a focusing optical system 97 provided between the image photosynthesis element 50 and the light-receiving element 60. The focusing optical system 97 is composed of, for example, a single convex lens 97a. The focusing optical system 97 focuses the detected light PL emitted from the third side surface 50c of the image photosynthesis element 50 toward the light-receiving surface of the light-receiving element 60. According to the modified projector 100A, the size of the light-receiving element 60 can be reduced by focusing the light to be detected PL with the light-collecting optical system 97. Furthermore, the configurations of the second and third embodiments may be combined with the light-gathering optical system 97 of this modified example.

[0068] (Second variation) Next, a second modified example of the projector of the present invention will be described. Components common to this modified example and the first embodiment are denoted by the same reference numerals, and detailed explanations will be omitted.

[0069] Figure 8B shows the main components of this modified example. As shown in Figure 8B, the projector 100B of this modified example includes a focusing optical system 98 provided between the image photosynthesis element 50 and the light-receiving element 60. The focusing optical system 98 of this modified example is composed of a concave mirror 98a. The focusing optical system 98 focuses the light to be detected PL emitted from the third side surface 50c of the image photosynthesis element 50 toward the light-receiving surface of the light-receiving element 60, while bending the optical path of the light to be detected PL toward the -X side.

[0070] In this modified projector 100B, since the focusing optical system 98 is composed of a concave mirror 98a, chromatic aberration does not occur compared to the first modified example, and the size of the focusing spot of the detected light PL on the light-receiving surface of the light-receiving element 60 can be made smaller. Therefore, further miniaturization of the light-receiving element 60 can be achieved. In addition, by bending the optical path of the detected light PL with the focusing optical system 98, the degree of freedom in the installation position of the light-receiving element 60 can be improved. Furthermore, the condensing optical system 98 of this modified example may be combined with the configurations of the second and third embodiments.

[0071] (Third variation) Next, a third modified example of the projector of the present invention will be described. Components common to this modified example and the first embodiment are denoted by the same reference numerals, and detailed explanations will be omitted.

[0072] Figure 8C shows the main components of this modified example. As shown in Figure 8C, the light-receiving element 61 in the projector 100C of this modified example is an image sensor 61a. The image sensor 61a is composed of, for example, a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), and acquires the detected light PL, which is imaged by the focusing lens 62, as an image.

[0073] In this modified version of projector 100C, a light-receiving element 61 consisting of an image sensor 61a is provided, enabling high-precision detection of color unevenness within the plane of the detected light PL. This allows for adjustment of the white balance considering color unevenness within the plane of the image light GP. Thus, projector 100C that projects high-quality image light GP without color unevenness can be realized. Furthermore, the light-receiving element 61 can also detect the shift in the focusing position of the light incident from the first light modulation panel 30 and the second light modulation panel 40. Therefore, in this modified version of projector 100C, alignment misalignment of the first light modulation panel 30 and the second light modulation panel 40 can also be detected. Furthermore, the light-receiving element 61 of this modified example may be combined with the configurations of the second and third embodiments.

[0074] (Fourth variation) Next, a fourth modified example of the projector of the present invention will be described. Components common to this modified example and the first embodiment are denoted by the same reference numerals, and their details will not be described further.

[0075] Figure 8D shows the main components of this modified example. As shown in Figure 8D, the light-receiving element 63 in the projector 100D of this modified example is a photoelectric conversion element 63a. The photoelectric conversion element 63a receives the detected light PL incident from the third side surface 50c of the image photosynthesis element 50 and converts it into electricity.

[0076] In this modified version, projector 100D supplies power converted by the photoelectric conversion element 63a to at least one of the light source device 10, the first optical modulation panel 30, and the second optical modulation panel 40. Therefore, according to this modified version, projector 100D improves light utilization efficiency and realizes a projector with excellent energy-saving performance by reusing the component of light emitted from the light source device that is not used for image generation as driving power.

[0077] 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, and materials of each component of the projector are not limited to the above embodiment and can be modified as appropriate. For example, in the above embodiment and modified example, the light-receiving element 60 is positioned opposite the third side surface 50c of the image photosynthesis element 50, and the projection optical device 70 projects the image light GP emitted from the fourth side surface 50d of the image photosynthesis element 50. However, the light-receiving element 60 may be positioned opposite the fourth side surface 50d of the image photosynthesis element 50, and the projection optical device 70 may be positioned opposite the third side surface 50c of the image photosynthesis element 50. In this case, the polarization directions of the first image-generating light L11 and the second image-generating light L21 are reversed, and the polarization directions of the first non-image-generating light L12 and the second non-image-generating light L22 are reversed.

[0078] Furthermore, in the above embodiments and modifications, a glass plate that oscillates in a plane perpendicular to the optical axis may be placed between the fourth side surface 50d of the image photosynthesis element 50 and the projection optical device 70 to perform pixel enhancement, which simulates increasing the number of pixels in the projected image.

[0079] A summary of this disclosure is provided below.

[0080] (Note 1) A light source device that emits, in a time-division manner, a first light in a first wavelength band, a second light in a second wavelength band different from the first wavelength band, and a third light in a third wavelength band different from the first and second wavelength bands. A polarization separation element that separates each of the first light, second light, and third light emitted from the light source device into a first polarization and a second polarization having a different polarization direction from the first polarization, A first light modulation panel that modulates the first polarization of the first light, the second light, and the third light incident from the polarization separation element, A second optical modulation panel modulates the second polarization of the first light, the second light, and the third light incident from the polarization separation element, An image photosynthesis element that generates image light by combining a portion of the first modulated light emitted from the first optical modulation panel and a portion of the second modulated light emitted from the second optical modulation panel, The image photosynthesis element includes a light-receiving element that receives light emitted from a third surface different from the first surface facing the first light modulation panel and the second surface facing the second light modulation panel, The image photosynthesis element comprises a projection optical device that projects image light emitted from a fourth surface different from the first, second, and third surfaces, The third surface of the image photosynthesis element emits the other part of the first modulated light and the other part of the second modulated light toward the light receiving element. projector.

[0081] With this projector configuration, components of the modulated light from the first and second optical modulation panels that are not used for image generation can be utilized as detected light for the photodetector. Therefore, the output polarizing element, which was placed downstream of the optical modulation device to block out the light components not used for image generation in conventional projectors, can be omitted. Thus, a projector with significantly improved light utilization efficiency of the light source device can be provided.

[0082] (Note 2) The polarization separation element includes a first polarization separation film that transmits the first polarization and reflects the second polarization. The image photosynthesis element includes a second polarization separation film that transmits the first polarization of the first modulated light and the second modulated light, and reflects the second polarization of the first modulated light and the second modulated light. The projector described in Appendix 1.

[0083] This configuration allows the polarization separation element to separate the colored light emitted from the light source into two optical paths by polarization separation, and to direct each optical path into the first and second optical modulation panels. Furthermore, in the image photosynthesis element, it is possible to separate the polarizations contained in the modulated light of the first and second optical modulation panels that are not used for image generation.

[0084] (Note 3) The second polarization separation film of the image photosynthesis element reflects the second polarization of the first modulated light and emits it from the third surface toward the photodetector, and transmits the first polarization of the second modulated light and emits it from the third surface toward the photodetector. The projector described in Appendix 2.

[0085] This configuration allows for the separation of polarizations not used for image generation from the modulated light of the first and second optical modulation panels and to be incident on the photodetector.

[0086] (Note 4) In the image photosynthesis element, the first and fourth surfaces face opposite each other, and the second and third surfaces face opposite each other. The projector described in Appendix 3.

[0087] With this configuration, the image photosynthesis element can be made up of a cube-shaped beam splitter. This allows the modulation light incident from the first and second surfaces to be polarized and separated by the second polarization separation film, one of the polarized components to be emitted as image light from the fourth surface toward the projection optical device, and the other polarized component to be emitted as detected light from the third surface toward the photodetector.

[0088] (Note 5) The system further comprises a first reflective mirror that reflects the first polarized light emitted from the polarization separation element toward the first optical modulation panel, and a second reflective mirror that reflects the second polarized light emitted from the polarization separation element toward the second optical modulation panel. A projector listed in any one of the appendices 1 through 4.

[0089] With this configuration, two polarized signals separated by a polarization separation element can be incident on the first and second optical modulation panels, respectively.

[0090] (Note 6) The light received by the light-receiving element from the image photosynthesis element is a black-and-white inverted image of the image light. A projector listed in any one of the appendices 1 through 5.

[0091] With this configuration, by receiving a black-and-white inverted image of the image light, it is possible to obtain a good color balance of the image light.

[0092] (Note 7) The system further includes a control device that controls at least one of the light source device, the first optical modulation panel, and the second optical modulation panel to adjust the color balance of the image light based on the light reception result of the light receiving element. A projector listed in any one of the appendices 1 through 6.

[0093] This configuration allows for adjustment of the image light's white balance based on the light-receiving result of the photodetector. Therefore, it is possible to provide a projector that projects high-quality images with an optimally adjusted white balance.

[0094] (Note 8) The light source device comprises a first light source that emits the first light, a second light source that emits the second light, and a third light source that emits the third light. The projector described in Appendix 7.

[0095] This configuration allows for simple and highly accurate control of the image light's white balance by controlling the output of three light sources corresponding to the three primary colors of light.

[0096] (Note 9) The system further comprises a polarization conversion unit provided between the image photosynthesis element and the light receiving element, which changes the polarization state of the light emitted from the third surface of the image photosynthesis element and received by the light receiving element. A projector listed in any one of the appendices 1 through 8.

[0097] With this configuration, the polarization state of the light received by the photodetector changes due to the polarization conversion unit, allowing the information received by the photodetector to be switched. Therefore, the white balance of the image light can be adjusted with higher precision and efficiency.

[0098] (Note 10) The polarization conversion unit includes a glass plate that transmits the other part of the first modulated light and the other part of the second modulated light, a first polarizing plate that transmits the other part of the first modulated light, and a second polarizing plate that transmits the other part of the second modulated light, and is switchable between a first state in which the glass plate is facing the third surface, a second state in which the first polarizing plate is facing the third surface, and a third state in which the second polarizing plate is facing the third surface. The projector described in Appendix 9.

[0099] This configuration allows for a simple switching of the information received by the photodetector by switching between the first, second, and third states.

[0100] (Note 11) The polarization conversion unit includes a phase difference plate rotatably mounted at a position facing the third surface of the image photosynthesis element, and a third polarizing plate into which light emitted from the phase difference plate is incident. The projector described in Appendix 9.

[0101] With this configuration, the polarization state of the light received by the photodetector can be changed by adjusting the rotation angle of the phase difference plate, making it easy to switch the information received by the photodetector.

[0102] (Note 12) The system further comprises a focusing optical system provided between the image photosynthesis element and the light receiving element, which focuses the light emitted from the third surface of the image photosynthesis element toward the light receiving element. A projector listed in any one of the appendices 1 through 11.

[0103] With this configuration, the light to be detected can be focused by the focusing optical system, allowing for a reduction in the size of the light-receiving element.

[0104] (Note 13) The light-receiving element is an image sensor that captures light emitted from the third surface of the image photosynthesis element. A projector listed in any one of the appendices 1 through 12.

[0105] This configuration allows for high-precision detection of color unevenness within the surface of the detected light using the photodetector. Therefore, it becomes possible to adjust the color balance while considering color unevenness within the image light. Thus, a projector that projects high-quality image light without color unevenness can be realized. Furthermore, the photodetector can also detect alignment misalignment between the first and second optical modulation panels.

[0106] (Note 14) The light-receiving element is a photoelectric conversion element that converts light emitted from the third surface of the image photosynthesis element into electrical energy. The projector described in Appendix 1.

[0107] This configuration allows for improved light utilization efficiency and the realization of an energy-saving projector by reusing the components of the light emitted from the light source that are not used for image generation as driving power. [Explanation of symbols]

[0108] 10...Light source device, 11B...First light source, 11G...Second light source, 11R...Third light source, 20...Polarization separation element, 21...First polarization separation film, 30...First optical modulation panel, 40...Second optical modulation panel, 50...Image photosynthesis element, 51...Second polarization separation film, 60, 61, 63...Photodetector, 61a...Image sensor, 63a...Photoelectric conversion element, 70...Projection optics device, 81...First reflective mirror, 8 2...Second reflective mirror, 90,190...Polarization conversion unit, 91...First polarizer, 92...Second polarizer, 93...Glass plate, 97,98...Focusing optical system, 100,100A,100B,100C,100D,101,102...Projector, 162,192...Third polarizer, 191...Phase difference plate, CONT...Control device, GP...Image light, P1...First modulated light, P2...Second modulated light.

Claims

1. A light source device that emits, in a time-division manner, a first light in a first wavelength band, a second light in a second wavelength band different from the first wavelength band, and a third light in a third wavelength band different from the first and second wavelength bands. A polarization separation element separates each of the first light, second light, and third light emitted from the light source device into a first polarization and a second polarization having a different polarization direction from the first polarization. A first light modulation panel modulates the first polarization of the first light, the second light, and the third light incident from the polarization separation element, A second light modulation panel modulates the second polarization of the first light, the second light, and the third light incident from the polarization separation element, An image photosynthesis element that generates image light by combining a portion of the first modulated light emitted from the first optical modulation panel and a portion of the second modulated light emitted from the second optical modulation panel, The image photosynthesis element includes a light-receiving element that receives light emitted from a third surface different from the first surface facing the first light modulation panel and the second surface facing the second light modulation panel, The image photosynthesis element comprises a projection optical device that projects image light emitted from a fourth surface different from the first, second, and third surfaces, The third surface of the image photosynthesis element emits the other part of the first modulated light and the other part of the second modulated light toward the light receiving element. projector.

2. The polarization separation element includes a first polarization separation film that transmits the first polarization and reflects the second polarization. The image photosynthesis element includes a second polarization separation film that transmits the first polarization of the first modulated light and the second modulated light, and reflects the second polarization of the first modulated light and the second modulated light. The projector according to claim 1.

3. The second polarization separation film of the image photosynthesis element reflects the second polarization of the first modulated light and emits it from the third surface toward the photodetector, and transmits the first polarization of the second modulated light and emits it from the third surface toward the photodetector. The projector according to claim 2.

4. In the image photosynthesis element, the first and fourth surfaces face opposite each other, and the second and third surfaces face opposite each other. The projector according to claim 3.

5. The system further comprises a first reflective mirror that reflects the first polarized light emitted from the polarization separation element toward the first optical modulation panel, and a second reflective mirror that reflects the second polarized light emitted from the polarization separation element toward the second optical modulation panel. The projector according to claim 1 or claim 2.

6. The light received by the light-receiving element from the image photosynthesis element is a black-and-white inverted image of the image light. The projector according to claim 1 or claim 2.

7. The system further includes a control device that controls at least one of the light source device, the first optical modulation panel, and the second optical modulation panel to adjust the color balance of the image light based on the light reception result of the light receiving element. The projector according to claim 1 or claim 2.

8. The light source device comprises a first light source that emits the first light, a second light source that emits the second light, and a third light source that emits the third light. The projector according to claim 7.

9. The system further comprises a polarization conversion unit provided between the image photosynthesis element and the light receiving element, which changes the polarization state of the light emitted from the third surface of the image photosynthesis element and received by the light receiving element. The projector according to claim 1 or claim 2.

10. The polarization conversion unit includes a glass plate that transmits the other part of the first modulated light and the other part of the second modulated light, a first polarizing plate that transmits the other part of the first modulated light, and a second polarizing plate that transmits the other part of the second modulated light, and is switchable between a first state in which the glass plate is facing the third surface, a second state in which the first polarizing plate is facing the third surface, and a third state in which the second polarizing plate is facing the third surface. The projector according to claim 9.

11. The polarization conversion unit includes a phase difference plate rotatably mounted at a position facing the third surface of the image photosynthesis element, and a third polarizing plate into which light emitted from the phase difference plate is incident. The projector according to claim 9.

12. The system further comprises a focusing optical system provided between the image photosynthesis element and the light receiving element, which focuses the light emitted from the third surface of the image photosynthesis element toward the light receiving element. The projector according to claim 1 or claim 2.

13. The light-receiving element is an image sensor that captures light emitted from the third surface of the image photosynthesis element. The projector according to claim 1 or claim 2.

14. The light-receiving element is a photoelectric conversion element that converts light emitted from the third surface of the image photosynthesis element into electrical energy. The projector according to claim 1 or claim 2.

Images