Liquid crystal projector

Abstract

In a liquid crystal projector having a polarization beam splitter and a reflective liquid crystal panel having a color filter, a line-shaped bright-dark is suppressed from being visually recognized in a projected image. A liquid crystal projector has a light source, a polarization beam splitter, and a first reflective liquid crystal panel and a second reflective liquid crystal panel each having a color filter layer and a plurality of pixels. Each pixel includes a plurality of sub-pixels. When two sub-pixels corresponding to the same sub-pixel in a projected image are referred to as a sub-pixel group, there are a plurality of sub-pixel groups in which the combination of colors of the two sub-pixels is different. When a sub-pixel group in which the total value of the luminance index values of the colors of the two sub-pixels is the largest is referred to as a first type, the combination of colors of each sub-pixel group is set such that the total value of the luminance index values of the colors of the first type of sub-pixel group is smaller than in a case where the colors of the two sub-pixels are assumed to be the same for each sub-pixel group.

Description

Technical Field

[0001] This invention relates to liquid crystal projectors. Background Technology

[0002] LCD projectors are broadly classified into three-panel and single-panel types based on the number of LCD panels used. Compared to three-panel projectors, single-panel projectors are superior in terms of miniaturization, weight reduction, and lower cost. A single-panel LCD projector is disclosed, for example, in Patent Document 1.

[0003] The liquid crystal projector disclosed in Patent Document 1 includes a light source, a polarizing beam splitter, a reflective liquid crystal panel, and a projection lens. In the liquid crystal projector of Patent Document 1, light emitted from the light source is split into S-polarized light and P-polarized light by the polarizing beam splitter. The reflective liquid crystal panel has a color filter and is configured to receive P-polarized light transmitted through the polarizing beam splitter. The reflected light from the reflective liquid crystal panel, that is, the light modulated by the reflective liquid crystal panel, is projected onto the screen by the projection lens, thereby forming a projected image.

[0004] Furthermore, Patent Document 2 discloses a liquid crystal projector comprising a first reflective liquid crystal panel for receiving and modulating P-polarized light transmitted through a polarizing beam splitter, and a second reflective liquid crystal panel for receiving and modulating S-polarized light reflected by the polarizing beam splitter. Both the first and second reflective liquid crystal panels have color filters. The liquid crystal projector of Patent Document 2, by having a first reflective liquid crystal panel corresponding to P-polarized light and a second reflective liquid crystal panel corresponding to S-polarized light, can achieve high-brightness color display. Existing technical documents Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2008-268639 Patent Document 2: Japanese Patent Application Publication No. 2007-25598 Summary of the Invention The problem the invention aims to solve

[0006] The inventors of this application discovered a problem in liquid crystal projectors, such as those described in Patent Documents 1 and 2, which are reflective liquid crystal panels equipped with polarizing beam splitters and color filters, where linear brightness and darkness (uneven stripes) are sometimes visually perceptible in the projected image.

[0007] The embodiments of the present invention were made in view of the above-mentioned problems, and their object is to suppress the visually recognizable linear brightness and darkness in the projected image in a liquid crystal projector equipped with a polarizing beam splitter and a reflective liquid crystal panel with a color filter. Solution for solving the problem

[0008] This manual discloses the liquid crystal projector described in the following items.

[0009] [Project 1] A liquid crystal projector, comprising: A light source that emits white light; A polarization beam splitter that separates the white light emitted from the light source into S-polarized light and P-polarized light; A first reflective liquid crystal panel, configured to receive the S-polarized light; and The second reflective liquid crystal panel is configured to receive the P-polarized light. Each of the first and second reflective liquid crystal panels has a color filter layer and multiple pixels. Each of the plurality of pixels comprises a plurality of sub-pixels of mutually distinct colors. A projected image is formed by projecting reflected light from the first reflective liquid crystal panel and reflected light from the second reflective liquid crystal panel. In the liquid crystal projector, When each sub-pixel of the first reflective liquid crystal panel is referred to as a first sub-pixel, and each sub-pixel of the second reflective liquid crystal panel is referred to as a second sub-pixel, and the combination of the first sub-pixel and the second sub-pixel corresponding to the same sub-pixel in the projected image is referred to as a sub-pixel group, There exist multiple sub-pixel groups where the color combinations of the first sub-pixel and the second sub-pixel are different from each other. When the sub-pixel group whose sum of the brightness index values ​​of the first sub-pixel and the second sub-pixel in the multiple sub-pixel groups is the largest is called the first seed pixel group, The combination of the colors of the first sub-pixel and the second sub-pixel in each of the plurality of sub-pixel groups is set such that the total value of the first sub-pixel group is smaller than the case where the first sub-pixel and the second sub-pixel are assumed to be the same color for each of the plurality of sub-pixel groups.

[0010] [Project 2] According to the LCD projector described in Project 1, wherein... When the sub-pixel group with the smallest total value among the various sub-pixel groups is called the second seed pixel group... The combination of the colors of the first sub-pixel and the second sub-pixel in each of the plurality of sub-pixel groups is set such that the difference between the total value of the first seed pixel group and the total value of the second seed pixel group is smaller than the case where the first sub-pixel and the second sub-pixel are assumed to have the same color for each of the plurality of sub-pixel groups.

[0011] [Project 3] According to the liquid crystal projector described in Project 1 or 2, wherein, The first seed pixel group is a combination of the first color sub-pixel with the largest brightness index value and the second color sub-pixel with the smallest brightness index value among the plurality of sub-pixels.

[0012] [Project 4] According to the LCD projector described in Project 3, wherein... The plurality of sub-pixels includes sub-pixels of the first color, sub-pixels of the second color, and sub-pixels of the third color. The second seed pixel group is a combination of the sub-pixels of the third color.

[0013] [Project 5] According to any one of Projects 1 to 4, the liquid crystal projector described herein, wherein... The first seed pixel group is a combination of the sub-pixel of the color with the largest Y value in the XYZ color system and the sub-pixel of the color with the smallest Y value in the XYZ color system.

[0014] [Project 6] According to any one of Projects 1 to 5, the liquid crystal projector described herein, wherein... Each of the plurality of pixels comprises a red sub-pixel, a green sub-pixel, and a blue sub-pixel. The multiple sub-pixel groups include sub-pixel groups that are combinations of the red sub-pixels with each other, and sub-pixel groups that are combinations of the green sub-pixels and the blue sub-pixels.

[0015] [Project 7] According to the LCD projector described in Project 6, wherein... In each pixel of the first reflective liquid crystal panel, the red sub-pixel, the green sub-pixel, and the blue sub-pixel are arranged sequentially from one end of the projected image toward the other end of the projected image. Similarly, in each pixel of the second reflective liquid crystal panel, the red sub-pixel, the blue sub-pixel, and the green sub-pixel are arranged sequentially from the side corresponding to one end of the projected image toward the side corresponding to the other end of the projected image. or In each pixel of the first reflective liquid crystal panel, the green sub-pixel, the red sub-pixel, and the blue sub-pixel are arranged sequentially from one end of the projected image toward the other end of the projected image. In each pixel of the second reflective liquid crystal panel, the blue sub-pixel, the red sub-pixel, and the green sub-pixel are arranged sequentially from one end of the projected image toward the other end of the projected image.

[0016] [Project 8] The LCD projector described in any one of items 1 to 7, wherein... It also includes a projection optics system, which is used to magnify and project the reflected light from the first reflective liquid crystal panel and the reflected light from the second reflective liquid crystal panel.

[0017] [Project 9] The LCD projector described in any one of projects 1 to 8, wherein... The light source has peaks in its emission spectrum in the wavelength regions corresponding to each of the colors red, green, and blue.

[0018] [Project 10] The LCD projector described in any one of items 1 to 9, wherein... Each of the first and second reflective liquid crystal panels has a liquid crystal layer. The liquid crystal molecules contained in the liquid crystal layer are oriented along the surface when no voltage is applied. The orientation of the liquid crystal molecules, which have undergone planar alignment, is approximately parallel to the vibration direction of the S-polarized light or the P-polarized light. The phase difference Δn•d of the liquid crystal layer is approximately λ / 4 under a specified voltage application state. Invention Effects

[0019] According to an embodiment of the present invention, in a liquid crystal projector equipped with a polarizing beam splitter and a reflective liquid crystal panel having a color filter, it is possible to suppress the visually perceptible linear brightness and darkness in the projected image. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating a liquid crystal projector 100 according to an embodiment of the present invention. Figure 2A This is a schematic cross-sectional view of the first reflective liquid crystal panel 10 of the liquid crystal projector 100. Figure 2B This is a schematic cross-sectional view of the second reflective liquid crystal panel 20 of the liquid crystal projector 100. Figure 3A It is used to illustrate the use of S-polarized light L S The diagram illustrates the principle of the display, showing the black display state. Figure 3B It is used to illustrate the use of S-polarized light L S The diagram illustrates the principle of the display, showing the white display state. Figure 4A It is used to illustrate the use of P-polarized light L P A diagram illustrating the principle of the display, showing the black display state. Figure 4B It is used to illustrate the use of P-polarized light L P The diagram illustrates the principle of the display, showing the white display state. Figure 5 This is a diagram showing the sub-pixel configurations in the first liquid crystal panel 10 and the second liquid crystal panel 20 side by side. Figure 6 It is a diagram showing the configuration SA10 of the first sub-pixel and the configuration SA20 of the second sub-pixel in the projected image side by side. Figure 7 This is a schematic diagram illustrating a comparative example, the LCD projector 900. Figure 8 This is a diagram showing the sub-pixel configurations in the first LCD panel 10 and the second LCD panel 20 side-by-side in relation to the comparative example LCD projector 900. Figure 9 This is a diagram showing the configuration of the first sub-pixel SA10 and the configuration of the second sub-pixel SA920 in the projected image side by side in relation to the LCD projector 900 of the comparative example. Figure 10 It is a diagram showing the configuration of the first sub-pixel SA10 and the configuration of the second sub-pixel SA20 in the projected image side by side, showing the relationship between the magnitudes of the Y values ​​of red, green and blue, as well as the brightness when a white display is projected from the first liquid crystal panel 10 and the brightness when a white display is projected from the second liquid crystal panel 20. Figure 11 The diagram shows other examples of subpixel configurations in the first liquid crystal panel 10 and the second liquid crystal panel 20. Explanation of reference numerals in the attached figures 1. Light source 6. Polarizing Beam Splitter (PBS) 6a Polarization separation surface 10. First reflective LCD panel (first LCD panel) 11, 21 Active matrix substrates 11a, 21a, 12a, 22a substrate 12, 22 relative to the substrate 13, 23 Liquid Crystal Layers 14- and 24-pixel electrodes 15, 25 First Orientation Film 16, 26 color filter layers 16R and 26R red color filters 16G and 26G green color filters 16B and 26B blue color filters 20 Second reflective LCD panel (Second LCD panel) 31, 32 Convex lenses 100 LCD Projector L White light L S S-polarized light L P P-polarized light SC screen P pixel R Red Subpixel G Green Subpixel B Blue sub-pixel. Detailed Implementation

[0021] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments illustrated below.

[0022] First, refer to Figure 1 The configuration of the liquid crystal projector 100 according to an embodiment of the present invention will be explained. Figure 1 This is a schematic diagram of an LCD projector 100.

[0023] like Figure 1 As shown, the LCD projector 100 includes a light source 1, a polarizing beam splitter 6, a first reflective LCD panel 10, and a second reflective LCD panel 20.

[0024] Light source 1 emits white light L. Various light sources capable of emitting white light L can be used as light source 1. Light source 1 can be, for example, a pseudo-white LED comprising an LED emitting blue light and a yellow phosphor that emits yellow light when excited by blue light. Alternatively, light source 1 may also comprise an LED emitting red light, an LED emitting green light, and an LED emitting blue light.

[0025] The polarization beam splitter (hereinafter referred to as "PBS") 6 separates the white light L emitted from the light source 1 into S-polarized light L S and P-polarized light L P The S-polarized light L incident on PBS6 S The polarization component whose vibration direction is parallel to the z-axis in the figure is reflected in the polarization separation surface 6a of PBS6. In contrast, the P-polarized light L in the white light L incident on PBS6... P The polarization component whose vibration direction is orthogonal to the z-axis (parallel to the y-axis) in the figure is transmitted through the polarization separation surface 6a. PBS6 preferably enables the polarization of S-polarized light L over the widest possible wavelength range in the visible light region. S and P-polarized light L P Separation. PBS6 can be in various forms, such as cubic, plate, or grid.

[0026] The first reflective liquid crystal panel (hereinafter referred to as "the first liquid crystal panel") 10 is configured to receive S-polarized light L emitted from the PBS6. S The first liquid crystal panel 10 can modulate S-polarized light L according to the image signal. S .

[0027] The second reflective liquid crystal panel (hereinafter referred to as the "second liquid crystal panel") 20 is configured to receive P-polarized light L emitted from the PBS6. P The second LCD panel 20 can modulate P-polarized light L according to the image signal. P .

[0028] The LCD projector 100 also includes an illumination optical system configured between the light source 1 and the PBS6 and a projection optical system configured between the PBS6 and the screen SC.

[0029] The illumination optics system guides the white light L emitted from light source 1 to PBS6. Figure 1 In this example, a convex lens 31 is shown as an illumination optical system to amplify the white light L emitted from the light source 1, but the illumination optical system is not limited to this example. For example, the illumination optical system may also include at least one convex lens and / or at least one concave lens. Of course, the illumination optical system may also include optical components other than lenses.

[0030] The projection optics system magnifies and projects the reflected light from the first liquid crystal panel 10 and the reflected light from the second liquid crystal panel 20 onto the screen SC. Figure 1 In the example shown, a convex lens 32 is illustrated as a projection optical system, but the projection optical system is not limited to this example. For example, a projection optical system may also include at least one convex lens and / or at least one concave lens. Of course, a projection optical system may also include optical components other than lenses.

[0031] In the LCD projector 100, a projected image is formed on the screen SC by projecting reflected light from the first LCD panel 10 and reflected light from the second LCD panel 20. The projected image formed on the screen SC can also be described as a composite image obtained by combining the projected image of the reflected light from the first LCD panel 10 and the projected image of the reflected light from the second LCD panel 20.

[0032] Figure 2A and Figure 2B These are schematic cross-sectional views of the first liquid crystal panel 10 and the second liquid crystal panel 20, respectively.

[0033] like Figure 2A As shown, the first liquid crystal panel 10 includes: an active matrix substrate 11; a counter substrate 12 opposite to the active matrix substrate 11; and a liquid crystal layer 13 disposed between the active matrix substrate 11 and the counter substrate 12. Furthermore, the first liquid crystal panel 10 has a plurality of pixels arranged in a matrix. Each pixel contains a plurality of sub-pixels of different colors. Here, each pixel includes a red sub-pixel (hereinafter referred to as a "red sub-pixel"), a green sub-pixel (hereinafter referred to as a "green sub-pixel"), and a blue sub-pixel (hereinafter referred to as a "blue sub-pixel").

[0034] The active matrix substrate 11 has pixel electrodes 14 disposed at each sub-pixel and a first alignment film 15 disposed in connection with the liquid crystal layer 13. Although not shown here, the active matrix substrate 11 also has thin-film transistors (TFTs) electrically connected to the pixel electrodes 14, wiring for supplying signals to the TFTs, etc. The aforementioned pixel electrodes 14 are supported by an insulating substrate 11a. The pixel electrodes 14 may be formed of a highly reflective metal material, functioning as a reflective layer. Alternatively, the pixel electrodes 14 may be formed of a transparent conductive material, with a reflective layer disposed independently of the pixel electrodes 14.

[0035] The substrate 12 has a color filter layer 16 and a second alignment film 17 disposed in contact with the liquid crystal layer 13. The color filter layer 16 includes a red color filter 16R, a green color filter 16G, and a blue color filter 16B. The red color filter 16R, the green color filter 16G, and the blue color filter 16B are arranged, for example, in a strip arrangement. The aforementioned color filter layer 16 is supported by a transparent and insulating substrate 12a.

[0036] The display mode of the first liquid crystal panel 10 can be, for example, a horizontal alignment mode or a vertical alignment mode. In the horizontal alignment mode, the liquid crystal molecules contained in the liquid crystal layer 13 are homogeneously aligned (that is, they are aligned approximately parallel to the substrate surfaces of the active matrix substrate 11 and the opposing substrate 12) in a voltage-free state. In the vertical alignment mode, the liquid crystal molecules contained in the liquid crystal layer 13 are aligned approximately perpendicular to the substrate surfaces of the active matrix substrate 11 and the opposing substrate 12 in a voltage-free state.

[0037] Although not shown here, the first liquid crystal panel 10 also has a common electrode for applying voltage to the liquid crystal layer 13 together with the pixel electrode 14. In a display mode utilizing a vertical electric field, the common electrode is disposed on the side opposite to the substrate 12. In a display mode utilizing a horizontal electric field, the common electrode is disposed on the side of the active matrix substrate 11.

[0038] like Figure 2B As shown, the second liquid crystal panel 20 includes: an active matrix substrate 21; a counter substrate 22 opposite to the active matrix substrate 21; and a liquid crystal layer 23 disposed between the active matrix substrate 21 and the counter substrate 22. Furthermore, the second liquid crystal panel 20 has a plurality of pixels arranged in a matrix. Each pixel contains a plurality of sub-pixels of different colors. Here, each pixel includes red sub-pixels, green sub-pixels, and blue sub-pixels.

[0039] The active matrix substrate 21 has pixel electrodes 24 disposed on each sub-pixel and a first alignment film 25 disposed in connection with the liquid crystal layer 23. Although not shown here, the active matrix substrate 21 also has TFTs electrically connected to the pixel electrodes 24, wiring for supplying signals to the TFTs, etc. The aforementioned pixel electrodes 24, etc., are supported by an insulating substrate 21a. The pixel electrodes 24 may be formed of a highly reflective metal material, functioning as a reflective layer. Alternatively, the pixel electrodes 24 may be formed of a transparent conductive material, with a reflective layer disposed independently of the pixel electrodes 24.

[0040] The substrate 22 has a color filter layer 26 and a second alignment film 27 disposed in contact with the liquid crystal layer 23. The color filter layer 26 includes a red color filter 26R, a green color filter 26G, and a blue color filter 26B. The red color filter 26R, the green color filter 26G, and the blue color filter 26B are arranged, for example, in a strip arrangement. The aforementioned color filter layer 26 is supported by a transparent and insulating substrate 22a.

[0041] The display mode of the second liquid crystal panel 20 can be, for example, a horizontal alignment mode or a vertical alignment mode. In the horizontal alignment mode, the liquid crystal molecules contained in the liquid crystal layer 23 are aligned along the surface (that is, aligned approximately parallel to the substrate surfaces of the active matrix substrate 21 and the opposing substrate 22) in a voltage-free state. In the vertical alignment mode, the liquid crystal molecules contained in the liquid crystal layer 23 are aligned approximately perpendicular to the substrate surfaces of the active matrix substrate 21 and the opposing substrate 22 in a voltage-free state.

[0042] Although not shown here, the second liquid crystal panel 20 also has a common electrode for applying voltage to the liquid crystal layer 23 together with the pixel electrode 24. In a display mode utilizing a vertical electric field, the common electrode is disposed on the side opposite to the substrate 22. In a display mode utilizing a horizontal electric field, the common electrode is disposed on the side of the active matrix substrate 21.

[0043] The first liquid crystal panel 10 and the second liquid crystal panel 20 are positioned in such a way that the projected images from their respective reflected light are aligned on the screen SC.

[0044] Here, the display principle of the LCD projector 100 will be explained.

[0045] First, refer to Figure 3A and Figure 3B For utilizing S-polarized light L S The display will be explained. Figure 3A and Figure 3B The images show the black and white display states, respectively.

[0046] As already explained, the S-polarized light L in the white light L emitted from light source 1 S The light is reflected by the polarization separation surface 6a of the PBS6 and goes to the first liquid crystal panel 10. In the case of black display, the liquid crystal layer 13 of the first liquid crystal panel 10 is not subjected to voltage, and the orientation of the liquid crystal molecules contained in the liquid crystal layer 13 is relative to the S-polarized light L. S The vibration directions are roughly parallel or roughly orthogonal. Therefore, as... Figure 3A As shown, the S-polarized light L incident on the first liquid crystal panel 10 S While maintaining S-polarized light L S The light is reflected in its original state and goes to PBS6. The S-polarized light L, as reflected light from the first liquid crystal panel 10, is... S Because it is reflected by the polarization separation surface 6a of PBS6, it will not be projected onto the screen SC and will appear as a black display.

[0047] In contrast, when displaying white, the liquid crystal layer 13 of the first liquid crystal panel 10 is subjected to a predetermined voltage, and the orientation of the liquid crystal molecules is relative to the S-polarized light L.S The vibration direction is at a specified angle (e.g., 45°). The phase difference Δn•d of the liquid crystal layer 13 in this state is set to approximately λ / 4, therefore... Figure 3B As shown, the S-polarized light L incident on the first liquid crystal panel 10 S Converted into P-polarized light L P And then to PBS6. The P-polarized light L, as reflected light from the first liquid crystal panel 10. P Because it passes through the polarization separation surface 6a of PBS6, it is projected onto the screen SC and becomes a white display.

[0048] Next, refer to Figure 4A and Figure 4B For utilizing P-polarized light L P The display will be explained. Figure 4A and Figure 4B The images show the black and white display states, respectively.

[0049] As already explained, the P-polarized light L in the white light L emitted from light source 1 P The light passes through the polarization separation surface 6a of the PBS6 and proceeds to the second liquid crystal panel 20. In the case of black display, the liquid crystal layer 23 of the second liquid crystal panel 20 is not subjected to voltage, and the orientation of the liquid crystal molecules contained in the liquid crystal layer 23 is relative to the P-polarized light L. P The vibration directions are roughly parallel or roughly orthogonal. Therefore, as... Figure 4A As shown, P-polarized light L incident on the second liquid crystal panel 20 P While maintaining P-polarized light L P The light is reflected in its original state and goes to PBS6. The P-polarized light L, as reflected light from the second liquid crystal panel 20, is... P Because the polarization separation surface 6a of PBS6 is transmitted through it, it will not be projected onto the screen SC and will appear as a black display.

[0050] In contrast, when displaying white, the liquid crystal layer 23 of the second liquid crystal panel 20 is subjected to a predetermined voltage, and the orientation of the liquid crystal molecules is relative to the P-polarized light L. P The vibration direction is at a specified angle (e.g., 45°). The phase difference Δn•d of the liquid crystal layer 23 in this state is set to approximately λ / 4, therefore... Figure 4B As shown, P-polarized light L incident on the second liquid crystal panel 20 P Converted into S-polarized light L S And then to PBS6. The S-polarized light L, as reflected light from the second liquid crystal panel 20. S Because it is reflected by the polarization separation surface 6a of PBS6, it is projected onto the screen SC and displayed as white.

[0051] Next, the configuration of sub-pixels in the liquid crystal projector 100 of this embodiment will be described.

[0052] Figure 5 This diagram shows the sub-pixel configurations of the first liquid crystal panel 10 and the second liquid crystal panel 20 side-by-side. (See diagram for example.) Figure 5 As shown, each pixel P of the first liquid crystal panel 10 and the second liquid crystal panel 20 is composed of a red sub-pixel R, a green sub-pixel G, and a blue sub-pixel B.

[0053] In the pixels P of the first liquid crystal panel 10, red sub-pixels R, green sub-pixels G, and blue sub-pixels B are arranged sequentially from one end of the projected image toward the other end (along the +x axis in the figure). Conversely, in the pixels P of the second liquid crystal panel 20, red sub-pixels R, blue sub-pixels B, and green sub-pixels G are arranged sequentially from one end of the projected image toward the other end (along the +y axis in the figure). In other words, the sub-pixel configuration of the second liquid crystal panel 20 can be considered as simply swapping the green sub-pixels G and blue sub-pixels B in the sub-pixel configuration of the first liquid crystal panel 10.

[0054] For ease of explanation, each sub-pixel of the first liquid crystal panel 10 is referred to as "first sub-pixel", and each sub-pixel of the second liquid crystal panel 20 is referred to as "second sub-pixel". Figure 6 It is a diagram showing the configuration SA10 of the first sub-pixel and the configuration SA20 of the second sub-pixel in the projected image side by side.

[0055] As from Figure 6 As can be understood, each pixel in the projected image (the projected image obtained by combining the projected image of the first liquid crystal panel 10 and the projected image of the second liquid crystal panel 20) is composed of the following sub-pixels: [1] a sub-pixel defined by the red sub-pixel R of the first liquid crystal panel 10 and the red sub-pixel R of the second liquid crystal panel 20; [2] a sub-pixel defined by the green sub-pixel G of the first liquid crystal panel 10 and the blue sub-pixel B of the second liquid crystal panel 20; and [3] a sub-pixel defined by the blue sub-pixel B of the first liquid crystal panel 10 and the green sub-pixel G of the second liquid crystal panel 20.

[0056] When the combination of the first subpixel and the second subpixel corresponding to the same subpixel in the projected image is called a "subpixel group", in the liquid crystal projector 100, there are multiple subpixel groups in which the color combination of the first subpixel and the second subpixel is different from each other. Specifically, there are subpixel groups that are combinations of red subpixels R (subpixel groups that define the subpixels of the above [1] in the projected image) and subpixel groups that are combinations of green subpixels G and blue subpixels B (subpixel groups that define the subpixels of the above [2] in the projected image and subpixel groups that define the subpixels of the above [3] in the projected image).

[0057] In this application specification, the subpixel group whose sum of the "luminance index values" of the colors of the first and second subpixels in a plurality of subpixel groups is the largest is called the "first seed pixel group," and the subpixel group whose sum of the colors of the first and second subpixels in a plurality of subpixel groups is the smallest is called the "second seed pixel group." The "luminance index value" is a value representing the brightness (brightness) of the color displayed by the subpixel, such as the Y value in the XYZ color system, but not limited to this. Furthermore, the luminance index value can be an absolute value obtained through optical measurement, or a relative value relative to a certain reference value. Hereinafter, the sum of the luminance index values ​​is sometimes referred to as the "luminance sum."

[0058] When pixel P is composed of red sub-pixels R, green sub-pixels G, and blue sub-pixels B, generally, the brightness index value of green sub-pixels G is the largest, and the brightness index value of blue sub-pixels is the smallest (that is, the brightness index value of red sub-pixels R is between the brightness index values ​​of green sub-pixels G and blue sub-pixels). When the brightness index value is the aforementioned Y value, when the Y value of white displayed by pixel P is set to 1, the Y value of red displayed by red sub-pixels R is, for example, approximately 0.25, the Y value of green displayed by green sub-pixels G is, for example, approximately 0.63, and the Y value of blue displayed by blue sub-pixels B is, for example, approximately 0.12. Therefore, in the liquid crystal projector 100 of this embodiment, the "first seed pixel group" is a sub-pixel group consisting of a combination of green sub-pixels G and blue sub-pixels B, and the "second seed pixel group" is a sub-pixel group consisting of combinations of red sub-pixels R.

[0059] The liquid crystal projector 100 of this embodiment, by having the above-described configuration, can suppress the visual recognition of linear brightness and darkness in the projected image. Hereinafter, with... Figure 7 The reason is explained by comparing it with the LCD projector 900 shown in the comparative example.

[0060] Figure 7This diagram shows a comparative example of a liquid crystal projector 900. The comparative example liquid crystal projector 900 has a configuration that is substantially the same as that of the liquid crystal projector 100 of this embodiment. However, the comparative example liquid crystal projector 900 includes a second liquid crystal panel 920 with a configuration that is different from that of the second liquid crystal panel 20 of the liquid crystal projector 100 of this embodiment.

[0061] Reference Figure 8 To illustrate the subpixel configuration in the comparative example LCD projector 900. Figure 8 This is a diagram showing the sub-pixel configurations in the first LCD panel 10 and the second LCD panel 920 side-by-side in relation to the comparative example LCD projector 900.

[0062] like Figure 8 As shown, in pixel P of the first liquid crystal panel 10, red sub-pixels R, green sub-pixels G, and blue sub-pixels B are arranged sequentially from the side corresponding to one end of the projected image to the side corresponding to the other end of the projected image (along the +x axis direction in the figure). Similarly, in pixel P of the second liquid crystal panel 920, red sub-pixels R, green sub-pixels G, and blue sub-pixels B are also arranged sequentially from the side corresponding to one end of the projected image to the side corresponding to the other end of the projected image (along the +y axis direction in the figure). In other words, the sub-pixel configuration of the second liquid crystal panel 920 is the same as that of the first liquid crystal panel 10.

[0063] Figure 9 This is a diagram showing the configuration of the first sub-pixel SA10 and the configuration of the second sub-pixel SA920 in the projected image side by side in relation to the LCD projector 900 of the comparative example.

[0064] As from Figure 9 As can be understood, each pixel in the projected image (the projected image obtained by combining the projected image of the first liquid crystal panel 10 and the projected image of the second liquid crystal panel 920) is composed of the following sub-pixels: [4] a sub-pixel defined by the red sub-pixel R of the first liquid crystal panel 10 and the red sub-pixel R of the second liquid crystal panel 920; [5] a sub-pixel defined by the green sub-pixel G of the first liquid crystal panel 10 and the green sub-pixel G of the second liquid crystal panel 920; and [6] a sub-pixel defined by the blue sub-pixel B of the first liquid crystal panel 10 and the blue sub-pixel B of the second liquid crystal panel 920.

[0065] In the comparative example liquid crystal projector 900, there are also multiple sub-pixel groups where the color combinations of the first sub-pixel and the second sub-pixel are different from each other. Specifically, there are sub-pixel groups that are combinations of red sub-pixels R (sub-pixel groups that define the sub-pixels of the above [4] in the projected image), sub-pixel groups that are combinations of green sub-pixels G (sub-pixel groups that define the sub-pixels of the above [5] in the projected image), and sub-pixel groups that are combinations of blue sub-pixels B (sub-pixel groups that define the sub-pixels of the above [6] in the projected image).

[0066] In the comparative example LCD projector 900, the "first seed pixel group" is a subpixel group consisting of green subpixels G combined with each other, and the "second seed pixel group" is a subpixel group consisting of blue subpixels B combined with each other.

[0067] In the comparative example of the liquid crystal projector 900 with the above-described configuration, it is possible to visually perceive linear brightness and darkness (uneven stripes) in the projected image. This is because the sum of the brightness of the first seed pixel group is large, and the difference between the sum of the brightness of the first seed pixel group and the sum of the brightness of the second seed pixel group is large. In a direct-viewing liquid crystal display device, the pixel size is set so that uneven stripes are not visually perceptible to the human eye. However, in the liquid crystal projector, since the image displayed by the liquid crystal panel is magnified and projected, it becomes a pixel size that allows the human eye to visually perceive uneven stripes.

[0068] In contrast, in the liquid crystal projector 100 of this embodiment, the sum of brightness of the first seed pixel group is smaller compared to the liquid crystal projector 900 of the comparative example. Taking the illustrated Y value as an example, the sum of brightness of the first seed pixel group is approximately 1.26 in the liquid crystal projector 900 of the comparative example, while it is approximately 0.75 in the liquid crystal projector 100 of this embodiment. Therefore, the visual perception of linear brightness and darkness in the projected image can be suppressed. Furthermore, in the liquid crystal projector 100 of this embodiment, the difference between the sum of brightness of the first seed pixel group and the sum of brightness of the second seed pixel group is smaller compared to the liquid crystal projector 900 of the comparative example. Taking the illustrated Y value as an example, the difference between the sum of brightness of the first seed pixel group and the sum of brightness of the second seed pixel group is approximately 1.02 in the liquid crystal projector 900 of the comparative example, while it is approximately 0.25 in the liquid crystal projector 100 of this embodiment. Therefore, the visual perception of linear brightness and darkness in the projected image can also be suppressed.

[0069] Thus, in the liquid crystal projector 100 of this embodiment, the color combination of the first sub-pixel and the second sub-pixel of each of the multiple sub-pixel groups is set such that the sum of the brightness of the first sub-pixel group is smaller than the case where the colors of the first sub-pixel and the second sub-pixel are assumed to be the same for each of the multiple sub-pixel groups (corresponding to the configuration of the liquid crystal projector 900 in the comparative example). Furthermore, in the liquid crystal projector 100 of this embodiment, the color combination of the first sub-pixel and the second sub-pixel of each of the multiple sub-pixel groups is set such that the difference between the sum of the brightness of the first sub-pixel group and the sum of the brightness of the second sub-pixel group is smaller than the case where the colors of the first sub-pixel and the second sub-pixel are assumed to be the same for each of the multiple sub-pixel groups (corresponding to the configuration of the liquid crystal projector 900 in the comparative example).

[0070] Here, we will describe the results of actual prototypes of the comparative example liquid crystal projector 900 and the liquid crystal projector 100 of this embodiment (hereinafter, the prototype liquid crystal projector 100 is referred to as the "Example") and the verification of whether linear brightness and darkness (uneven stripes) can be visually identified.

[0071] During the prototype manufacturing, an LED manufactured by ROHM (product name: MSL0402RGBU) was used as the light source 1, and a polarizing beam splitter manufactured by Edmund (product name: Broadband Stereo Polarizing B / S VIS) was used as the PBS6. Furthermore, the liquid crystal layers 13 and 23 of the first liquid crystal panel 10 and the second liquid crystal panel 20 (920) were formed using negative liquid crystal material, and their orientation in the voltage-free state was set to be aligned with the S-polarized light L. S or P-polarized light L P The vibration directions are roughly parallel. Furthermore, the cell thickness was set in such a way that the phase difference Δn•d of the liquid crystal layer when a white display voltage is applied is 140 nm.

[0072] Regarding the comparative examples and the embodiments, the in-plane uniformity of the projected image formed on the screen SC was visually evaluated. The results showed that stripe unevenness was visually identifiable in the comparative examples, but not in the embodiments, indicating high in-plane uniformity. This confirms that the embodiments effectively suppressed the visually identifiable linear brightness and darkness in the projected image.

[0073] Figure 10 Although it is with Figure 6 Similarly, the diagram shows the configurations SA10 of the first sub-pixel and SA20 of the second sub-pixel in the projected image side by side, but also shows the relationship between the Y values ​​of red, green and blue, the brightness when a white display is projected from the first liquid crystal panel 10, and the brightness when a white display is projected from the second liquid crystal panel 20.

[0074] from Figure 10 It can be seen that the line-like brightness and darkness in the image projected onto the first liquid crystal panel 10 are exactly reversed with the line-like brightness and darkness in the image projected onto the second liquid crystal panel 20. Therefore, in the image obtained by combining the two images (the final projected image), the in-plane uniformity is higher.

[0075] Thus, in the liquid crystal projector 100 of this embodiment, the visual recognition of linear brightness and darkness in the projected image is suppressed.

[0076] Furthermore, the configuration of subpixels in each pixel P is not limited to Figure 5 The example shown. In Figure 5 In the example shown, in each pixel P of the first liquid crystal panel 10, red sub-pixel R, green sub-pixel G, and blue sub-pixel B are arranged in sequence from the side corresponding to one end of the projected image to the side corresponding to the other end of the projected image, and in each pixel P of the second liquid crystal panel 20, red sub-pixel R, blue sub-pixel B, and green sub-pixel G are arranged in sequence from the side corresponding to one end of the projected image to the side corresponding to the other end of the projected image.

[0077] In contrast, for example, one could also use... Figure 11 The subpixel configuration shown. Figure 11 In the example shown, in each pixel P of the first liquid crystal panel 10, a green sub-pixel G, a red sub-pixel R, and a blue sub-pixel B are arranged sequentially from one end of the projected image toward the other end of the projected image. Similarly, in each pixel P of the second liquid crystal panel 20, a blue sub-pixel B, a red sub-pixel R, and a green pixel G are arranged sequentially from one end of the projected image toward the other end of the projected image. (The last sentence appears to be incomplete and possibly refers to a specific example or feature.) Figure 11 Even with the sub-pixel configuration shown, it is still possible to obtain the same result as when using... Figure 5 The same effect is achieved with the configuration of the sub-pixels shown.

[0078] Furthermore, in the explanations so far, an example has been shown where each pixel P is composed of three sub-pixels: red sub-pixel R, green sub-pixel G, and blue sub-pixel B. However, the number of sub-pixels constituting pixel P and the combination of colors are not limited to this example.

[0079] The first seed pixel group can be, for example, a combination of a sub-pixel of the first color with the largest luminance index value and a sub-pixel of the second color with the smallest luminance index value. The second seed pixel group can be a combination of sub-pixels of a third color that are different from the first and second colors.

[0080] Alternatively, the first seed pixel group can be, for example, a combination of the sub-pixel with the color having the largest Y value and the sub-pixel with the color having the smallest Y value among multiple sub-pixels.

[0081] From the perspective of improving light utilization efficiency or color reproduction, the preferred light source 1 has a peak in the emission spectrum in the wavelength region corresponding to each of the colors red, green and blue.

[0082] From the viewpoint of reducing costs by omitting the phase retardation plate, the display mode of the first liquid crystal panel 10 and the second liquid crystal panel 20 is preferably a horizontal alignment mode. In the case of the horizontal alignment mode, it is suitable to adopt the following configuration: the orientation of the liquid crystal molecules that have undergone planar alignment in the absence of applied voltage is aligned with the S-polarized light L. S or P-polarized light L P The vibration directions are roughly parallel, and the phase difference Δn•d between liquid crystal layers 13 and 23 is approximately λ / 4 under the specified voltage (specifically, the white display voltage). Here, "the phase difference Δn•d is approximately λ / 4" means that it substantially satisfies the λ / 4 condition relative to visible light with a wavelength of 550 nm (for example, Δn•d is in the range of 137.5 ± 10 nm). Industrial availability

[0083] According to an embodiment of the present invention, in a liquid crystal projector equipped with a polarizing beam splitter and a reflective liquid crystal panel having a color filter, it is possible to suppress the visually perceptible linear brightness and darkness in the projected image.

Claims

1. A liquid crystal projector, comprising: A light source that emits white light; A polarization beam splitter that separates the white light emitted from the light source into S-polarized light and P-polarized light; A first reflective liquid crystal panel, configured to receive the S-polarized light; and The second reflective liquid crystal panel is configured to receive the P-polarized light. Each of the first and second reflective liquid crystal panels has a color filter layer and multiple pixels. Each of the plurality of pixels comprises a plurality of sub-pixels of mutually distinct colors. A projected image is formed by projecting reflected light from the first reflective liquid crystal panel and reflected light from the second reflective liquid crystal panel. The liquid crystal projector is characterized in that... When each sub-pixel of the first reflective liquid crystal panel is referred to as a first sub-pixel, and each sub-pixel of the second reflective liquid crystal panel is referred to as a second sub-pixel, and the combination of the first sub-pixel and the second sub-pixel corresponding to the same sub-pixel in the projected image is referred to as a sub-pixel group, There exist multiple sub-pixel groups where the color combinations of the first sub-pixel and the second sub-pixel are different from each other. When the sub-pixel group whose sum of the brightness index values ​​of the first sub-pixel and the second sub-pixel in the multiple sub-pixel groups is the largest is called the first seed pixel group, The combination of the colors of the first sub-pixel and the second sub-pixel in each of the plurality of sub-pixel groups is set such that the total value of the first sub-pixel group is smaller than the case where the first sub-pixel and the second sub-pixel are assumed to be the same color for each of the plurality of sub-pixel groups.

2. The liquid crystal projector according to claim 1, wherein, When the sub-pixel group with the smallest total value among the various sub-pixel groups is called the second seed pixel group... The combination of the colors of the first sub-pixel and the second sub-pixel in each of the plurality of sub-pixel groups is set such that the difference between the total value of the first seed pixel group and the total value of the second seed pixel group is smaller than the case where the first sub-pixel and the second sub-pixel are assumed to have the same color for each of the plurality of sub-pixel groups.

3. The liquid crystal projector according to claim 1 or 2, wherein, The first seed pixel group is a combination of the first color sub-pixel with the largest brightness index value and the second color sub-pixel with the smallest brightness index value among the plurality of sub-pixels.

4. The liquid crystal projector according to claim 3, wherein, The plurality of sub-pixels includes sub-pixels of the first color, sub-pixels of the second color, and sub-pixels of the third color. When the sub-pixel group with the smallest total value among the various sub-pixel groups is called the second seed pixel group... The second seed pixel group is a combination of the sub-pixels of the third color.

5. The liquid crystal projector according to claim 1 or 2, wherein, The first seed pixel group is a combination of the sub-pixel of the color with the largest Y value in the XYZ color system and the sub-pixel of the color with the smallest Y value in the XYZ color system.

6. The liquid crystal projector according to claim 1 or 2, wherein, Each of the plurality of pixels comprises a red sub-pixel, a green sub-pixel, and a blue sub-pixel. The multiple sub-pixel groups include sub-pixel groups that are combinations of the red sub-pixels with each other, and sub-pixel groups that are combinations of the green sub-pixels and the blue sub-pixels.

7. The liquid crystal projector according to claim 6, wherein, In each pixel of the first reflective liquid crystal panel, the red sub-pixel, the green sub-pixel, and the blue sub-pixel are arranged sequentially from one end of the projected image toward the other end of the projected image. Similarly, in each pixel of the second reflective liquid crystal panel, the red sub-pixel, the blue sub-pixel, and the green sub-pixel are arranged sequentially from the side corresponding to one end of the projected image toward the side corresponding to the other end of the projected image. or In each pixel of the first reflective liquid crystal panel, the green sub-pixel, the red sub-pixel, and the blue sub-pixel are arranged sequentially from one end of the projected image toward the other end of the projected image. In each pixel of the second reflective liquid crystal panel, the blue sub-pixel, the red sub-pixel, and the green sub-pixel are arranged sequentially from one end of the projected image toward the other end of the projected image.

8. The liquid crystal projector according to claim 1 or 2, wherein, It also includes a projection optics system, which is used to magnify and project the reflected light from the first reflective liquid crystal panel and the reflected light from the second reflective liquid crystal panel.

9. The liquid crystal projector according to claim 1 or 2, wherein, The light source has peaks in its emission spectrum in the wavelength regions corresponding to each of the colors red, green, and blue.

10. The liquid crystal projector according to claim 1 or 2, wherein, Each of the first and second reflective liquid crystal panels has a liquid crystal layer. The liquid crystal molecules contained in the liquid crystal layer are oriented along the surface when no voltage is applied. The orientation of the liquid crystal molecules, which have undergone planar alignment, is approximately parallel to the vibration direction of the S-polarized light or the P-polarized light. The phase difference Δn•d of the liquid crystal layer is approximately λ / 4 under a specified voltage application state.

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