LCD projector

Abstract

In a liquid crystal projector equipped with a polarizing beam splitter and a reflective liquid crystal panel having a color filter, the visibility of line-shaped areas of light and dark in the projected image is suppressed. [Solution] The liquid crystal projector comprises a light source, a polarizing beam splitter, and first and second reflective liquid crystal panels having a color filter layer and a plurality of pixels. Each pixel contains a plurality of subpixels. When two subpixels corresponding to the same subpixel in the projected image are called a subpixel set, there are multiple types of subpixel sets with different color combinations of the two subpixels. When the subpixel set that maximizes the sum of the luminance index values ​​of the two subpixels is called the first type, the color combinations of each subpixel set are set such that the sum of the luminance index values ​​of the first type subpixel set is smaller than when it is assumed that the two subpixels are the same color for each subpixel set.

Description

[Technical Field]

[0001] This invention relates to a liquid crystal projector. [Background technology]

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

[0003] The liquid crystal projector disclosed in Patent Document 1 comprises 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 separated into S-polarized and P-polarized light by the polarizing beam splitter. The reflective liquid crystal panel has a color filter and is arranged to receive the P-polarized light that has passed 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 to form a projected image.

[0004] Furthermore, Patent Document 2 discloses a liquid crystal projector comprising a first reflective liquid crystal panel for modulating P-polarized light transmitted through a polarizing beam splitter, and a second reflective liquid crystal panel for 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 can achieve high-brightness color display by comprising a first reflective liquid crystal panel corresponding to P-polarized light and a second reflective liquid crystal panel corresponding to S-polarized light. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2008-268639 [Patent Document 2] Japanese Patent Publication No. 2007-25598 [Overview of the project] [Problems that the invention aims to solve]

[0006] The inventors of the present invention have found a problem in liquid crystal projectors, such as the liquid crystal projectors described in Patent Documents 1 and 2, which are equipped with a reflective liquid crystal panel having a polarizing beam splitter and a color filter, in which line-shaped areas of light and dark (swirl marks) may be visible in the projected image.

[0007] Embodiments of the present invention have been made in view of the above problems, and their purpose is to suppress the visibility of line-shaped brightness and darkness in the projected image in a liquid crystal projector equipped with a polarizing beam splitter and a reflective liquid crystal panel having a color filter. [Means for solving the problem]

[0008] This specification discloses liquid crystal projectors as described in the following sections.

[0009] [Item 1] A light source that emits white light, A polarization beam splitter that separates the white light emitted from the light source into S-polarized and P-polarized light, A first reflective liquid crystal panel arranged to receive the aforementioned S-polarized light, A second reflective liquid crystal panel arranged to receive the P-polarized light, Equipped with, Each of the first reflective liquid crystal panel and the second reflective liquid crystal panel has a color filter layer and a plurality of pixels. Each of the aforementioned plurality of pixels includes a plurality of subpixels of different colors, A liquid crystal projector in which 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, When each sub-pixel of the first reflective liquid crystal panel is referred to as a first sub-pixel, each sub-pixel of the second reflective liquid crystal panel is referred to as a second sub-pixel, and a 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 set, a plurality of types of sub-pixel sets having different color combinations of the first sub-pixel and the second sub-pixel exist, among the plurality of types of sub-pixel sets, when a sub-pixel set in which the sum of the luminance index values of the colors of the first sub-pixel and the second sub-pixel is maximum is referred to as a first type of sub-pixel set, the color combination of the first sub-pixel and the second sub-pixel in each of the plurality of types of sub-pixel sets is set such that the total value of the first type of sub-pixel set is smaller than that in a case where it is assumed that the colors of the first sub-pixel and the second sub-pixel are the same for each of the plurality of types of sub-pixel sets, the liquid crystal projector.

[0010] [Item 2] among the plurality of types of sub-pixel sets, when a sub-pixel set in which the total value is minimum is referred to as a second type of sub-pixel set, the color combination of the first sub-pixel and the second sub-pixel in each of the plurality of types of sub-pixel sets is set such that a difference between the total value of the first type of sub-pixel set and the total value of the second type of sub-pixel set is smaller than that in a case where it is assumed that the colors of the first sub-pixel and the second sub-pixel are the same for each of the plurality of types of sub-pixel sets, the liquid crystal projector according to Item 1.

[0011] [Item 3] the first type of sub-pixel set is a combination of a sub-pixel of a first color having the maximum luminance index value among the plurality of sub-pixels and a sub-pixel of a second color having the minimum luminance index value, the liquid crystal projector according to Item 1 or 2.

[0012] [Item 4] The plurality of subpixels include a subpixel of the first color, a subpixel of the second color, and a subpixel of the third color. The liquid crystal projector described in item 3, wherein the second type of subpixel set is a combination of the third color subpixels.

[0013] [Item 5] The liquid crystal projector according to any one of items 1 to 4, wherein the first type of subpixel set is a combination of the subpixel of the color with the largest Y value in the XYZ color system and the subpixel of the color with the smallest Y value among the plurality of subpixels.

[0014] [Item 6] Each of the aforementioned plurality of pixels includes a red subpixel, a green subpixel, and a blue subpixel. The liquid crystal projector according to any one of items 1 to 5, wherein the multiple types of subpixel sets include a subpixel set which is a combination of the red subpixels and a subpixel set which is a combination of the green subpixels and the blue subpixels.

[0015] [Item 7] In each pixel of the first reflective liquid crystal panel, the red subpixel, the green subpixel, and the blue subpixel are arranged in this order from the side corresponding to one end of the projected image to the side corresponding to the other end, and in each pixel of the second reflective liquid crystal panel, the red subpixel, the blue subpixel, and the green subpixel are arranged in this order from the side corresponding to one end of the projected image to the side corresponding to the other end, or The liquid crystal projector according to item 6, wherein in each pixel of the first reflective liquid crystal panel, the green subpixel, the red subpixel, and the blue subpixel are arranged in this order from the side corresponding to one end of the projected image to the side corresponding to the other end, and in each pixel of the second reflective liquid crystal panel, the blue subpixel, the red subpixel, and the green subpixel are arranged in this order from the side corresponding to one end of the projected image to the side corresponding to the other end.

[0016] [Item 8] A liquid crystal projector according to any one of items 1 to 7, further comprising a projection optical system for magnifying and projecting reflected light from the first reflective liquid crystal panel and reflected light from the second reflective liquid crystal panel.

[0017] [Item 9] The liquid crystal projector according to any one of items 1 to 8, wherein the light source has emission spectral peaks in wavelength ranges corresponding to red, green, and blue, respectively.

[0018] [Item 10] Each of the first reflective liquid crystal panel and the second reflective liquid crystal panel has a liquid crystal layer, The liquid crystal molecules contained in the liquid crystal layer are homogeneously oriented in the absence of applied voltage. The orientation of the homogeneously oriented liquid crystal molecules is substantially parallel to the vibration direction of the S-polarized or P-polarized light. A liquid crystal projector according to any one of items 1 to 9, wherein the phase difference Δn·d of the liquid crystal layer is approximately λ / 4 under a predetermined voltage application condition. [Effects of the Invention]

[0019] According to embodiments 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, the visibility of line-shaped areas of brightness and darkness in the projected image can be suppressed. [Brief explanation of the drawing]

[0020] [Figure 1] This figure schematically shows a liquid crystal projector 100 according to an embodiment of the present invention. [Figure 2A] This is a schematic cross-sectional view showing the first reflective liquid crystal panel 10 of the liquid crystal projector 100. [Figure 2B] This is a schematic cross-sectional view showing the second reflective liquid crystal panel 20 of the liquid crystal projector 100. [Figure 3A]This diagram illustrates the principle of display using S-polarized LS, and shows the black display state. [Figure 3B] This diagram illustrates the principle of display using S-polarized LS, and shows the white display state. [Figure 4A] This diagram illustrates the principle of display using P-polarized LP (Photovoltaic Print), and shows the black display state. [Figure 4B] This diagram illustrates the principle of display using P-polarized LP (Photovoltaic Printing), showing the white display state. [Figure 5] This figure shows the subpixel arrangement in the first liquid crystal panel 10 and the subpixel arrangement in the second liquid crystal panel 20 side by side. [Figure 6] This figure shows the arrangement of the first subpixel SA10 and the arrangement of the second subpixel SA20 in the projected image side by side. [Figure 7] This diagram schematically shows the comparative example liquid crystal projector 900. [Figure 8] This figure shows the subpixel arrangement in the first liquid crystal panel 10 and the subpixel arrangement in the second liquid crystal panel 20 of the comparative example liquid crystal projector 900 side by side. [Figure 9] This figure shows the arrangement of the first subpixel SA10 and the arrangement of the second subpixel SA920 in the projected image of the comparative example liquid crystal projector 900. [Figure 10] This diagram shows the arrangement of the first subpixel SA10 and the arrangement of the second subpixel SA20 in the projected image side by side, and also shows the relative magnitudes of the Y values ​​of red, green, and blue, as well as the brightness when a white display is projected by the first liquid crystal panel 10 and the brightness when a white display is projected by the second liquid crystal panel 20. [Figure 11] This figure shows other examples of subpixel arrangements in the first liquid crystal panel 10 and the second liquid crystal panel 20. [Modes for carrying out the invention]

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

[0022] First, the configuration of the liquid crystal projector 100 according to an embodiment of the present invention will be described with reference to Figure 1. Figure 1 is a schematic diagram showing the liquid crystal projector 100.

[0023] As shown in Figure 1, the liquid crystal projector 100 comprises a light source 1, a polarizing beam splitter 6, a first reflective liquid crystal panel 10, and a second reflective liquid crystal 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 may be, for example, a pseudo-white LED including an LED that emits blue light and a yellow phosphor that emits yellow light when excited by blue light. Alternatively, light source 1 may include an LED that emits red light, an LED that emits green light, and an LED that emits blue light.

[0025] The polarizing beam splitter (hereinafter referred to as "PBS") 6 converts the white light L emitted from the light source 1 into S-polarized L S and P polarization L P It separates into two. Of the white light L incident on PBS6, S-polarized L S This is the polarization component whose vibration direction is parallel to the z-axis in the figure, and is reflected at the polarization separation plane 6a of PBS6. In contrast, the P-polarized L of the white light L incident on PBS6 P This is a polarization component whose vibration direction is perpendicular to the z-axis (parallel to the y-axis) in the figure, and it is transmitted through the polarization separation plane 6a. PBS6 is S-polarized L in as wide a wavelength range as possible within the visible light range. S and P polarization L P It is preferable that the two can be separated. PBS6 may be, for example, cube-shaped, plate-shaped, or wire grid-shaped.

[0026] The first reflective liquid crystal panel (hereinafter referred to as the "first liquid crystal panel") 10 receives S-polarized light emitted from PBS6. Sis arranged to receive the light. The first liquid crystal panel 10 modulates the S-polarized light L in accordance with an image signal S can be modulated.

[0027] The second reflective liquid crystal panel (hereinafter referred to as "second liquid crystal panel") 20 is arranged to receive the P-polarized light L emitted from the PBS 6 P is arranged to receive the light. The second liquid crystal panel 20 modulates the P-polarized light L in accordance with an image signal P can be modulated.

[0028] The liquid crystal projector 100 further includes an illumination optical system disposed between the light source 1 and the PBS 6, and a projection optical system disposed between the PBS 6 and the screen SC.

[0029] The illumination optical system guides the white light L emitted from the light source 1 to the PBS 6. Although FIG. 1 illustrates one convex lens 31 that expands the white light L emitted from the light source 1 as the illumination optical system, the illumination optical system is not limited to this example. The illumination optical system may include, for example, at least one convex lens and / or at least one concave lens. Of course, the illumination optical system may include optical members other than lenses.

[0030] The projection optical 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. Although FIG. 1 illustrates one convex lens 32 as the projection optical system, the projection optical system is not limited to this example. The projection optical system may include, for example, at least one convex lens and / or at least one concave lens. Of course, the projection optical system may include optical members other than lenses.

[0031] In the liquid crystal projector 100, a projected image is formed on the screen SC by projection of the reflected light from the first liquid crystal panel 10 and the reflected light from the second liquid crystal panel 20. It can also be said that the projected image formed on the screen SC is a composite of the projected image of the reflected light from the first liquid crystal panel 10 and the projected image of the reflected light from the second liquid crystal panel 20.

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

[0033] As shown in Figure 2A, the first liquid crystal panel 10 includes an active matrix substrate 11, a counter substrate 12 facing the active matrix substrate 11, and a liquid crystal layer 13 provided between the active matrix substrate 11 and the counter substrate 12. The first liquid crystal panel 10 also has a plurality of pixels arranged in a matrix. Each of the plurality of pixels contains a plurality of subpixels of different colors. Here, each pixel contains a red subpixel (hereinafter referred to as "red subpixel"), a green subpixel (hereinafter referred to as "green subpixel"), and a blue subpixel (hereinafter referred to as "blue subpixel").

[0034] The active matrix substrate 11 has pixel electrodes 14 provided for each subpixel and a first alignment film 15 provided in contact with the liquid crystal layer 13. Although not shown here, the active matrix substrate 11 further includes thin-film transistors (TFTs) electrically connected to the pixel electrodes 14 and wiring for supplying signals to the TFTs. The aforementioned pixel electrodes 14, etc., are supported by an insulating substrate 11a. The pixel electrodes 14 may be formed from a highly reflective metallic material and function as a reflective layer. Alternatively, the pixel electrodes 14 may be formed from a transparent conductive material, and a reflective layer may be provided separately from the pixel electrodes 14.

[0035] The opposing substrate 12 has a color filter layer 16 and a second alignment film 17 provided 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 arrangement of the red color filter 16R, green color filter 16G, and blue color filter 16B is, for example, a stripe arrangement. The above-described color filter layer 16, etc., is supported by a transparent and insulating substrate 12a.

[0036] The display mode of the first liquid crystal panel 10 may 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 (i.e., oriented approximately parallel to the substrate surfaces of the active matrix substrate 11 and the opposing substrate 12) when no voltage is applied. In the vertical alignment mode, the liquid crystal molecules contained in the liquid crystal layer 13 are oriented approximately perpendicular to the substrate surfaces of the active matrix substrate 11 and the opposing substrate 12 when no voltage is applied.

[0037] Although not shown in the diagram, the first liquid crystal panel 10 further includes a common electrode for applying voltage to the liquid crystal layer 13, along with the pixel electrodes 14. In the display mode utilizing the vertical electric field, the common electrode is located on the opposing substrate 12 side. In the display mode utilizing the horizontal electric field, the common electrode is located on the active matrix substrate 11 side.

[0038] As shown in Figure 2B, the second liquid crystal panel 20 includes an active matrix substrate 21, a counter substrate 22 facing the active matrix substrate 21, and a liquid crystal layer 23 provided between the active matrix substrate 21 and the counter substrate 22. The second liquid crystal panel 20 also has a plurality of pixels arranged in a matrix. Each of the plurality of pixels includes a plurality of subpixels of different colors. Here, each pixel includes a red subpixel, a green subpixel, and a blue subpixel.

[0039] The active matrix substrate 21 has pixel electrodes 24 provided for each subpixel and a first alignment film 25 provided in contact with the liquid crystal layer 23. Although not shown here, the active matrix substrate 21 further includes TFTs electrically connected to the pixel electrodes 24 and wiring for supplying signals to the TFTs. The aforementioned pixel electrodes 24, etc., are supported by an insulating substrate 21a. The pixel electrodes 24 may be formed from a highly reflective metallic material and function as a reflective layer. Alternatively, the pixel electrodes 24 may be formed from a transparent conductive material, and a reflective layer may be provided separately from the pixel electrodes 24.

[0040] The opposing substrate 22 has a color filter layer 26 and a second alignment film 27 provided 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 arrangement of the red color filter 26R, green color filter 26G, and blue color filter 26B is, for example, a stripe arrangement. The above-described color filter layer 26, etc., is supported by a transparent and insulating substrate 22a.

[0041] The display mode of the second liquid crystal panel 20 may 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 homogeneously aligned (i.e., oriented approximately parallel to the substrate surfaces of the active matrix substrate 21 and the opposing substrate 22) when no voltage is applied. In the vertical alignment mode, the liquid crystal molecules contained in the liquid crystal layer 23 are oriented approximately perpendicular to the substrate surfaces of the active matrix substrate 21 and the opposing substrate 22 when no voltage is applied.

[0042] Although not shown in the diagram, the second liquid crystal panel 20 further includes a common electrode for applying voltage to the liquid crystal layer 23, along with the pixel electrodes 24. In the display mode utilizing the vertical electric field, the common electrode is located on the opposing substrate 22 side. In the display mode utilizing the horizontal electric field, the common electrode is located on the active matrix substrate 21 side.

[0043] The first liquid crystal panel 10 and the second liquid crystal panel 20 are positioned so that the projected images of the reflected light from each panel coincide on the screen SC.

[0044] Here, we will explain the display principle of the LCD projector 100.

[0045] First, referring to Figures 3A and 3B, S-polarized L S This section explains the display using this method. Figures 3A and 3B show the black display state and the white display state, respectively.

[0046] As already explained, S-polarized L of the white light L emitted from light source 1 S However, it is reflected by the polarization separation surface 6a of PBS6 and directed toward the first liquid crystal panel 10. When displaying black, no voltage is applied to the liquid crystal layer 13 of the first liquid crystal panel 10, and the orientation of the liquid crystal molecules contained in the liquid crystal layer 13 is S-polarized L S The vibration direction is approximately parallel or perpendicular to it. Therefore, as shown in Figure 3A, the S-polarized light L incident on the first liquid crystal panel 10 S S polarized L S It is reflected as is and heads towards PBS6. S-polarized light is reflected from the first liquid crystal panel 10. S Since it is reflected by the polarization separation surface 6a of PBS6, it is not projected onto the screen SC and appears as black.

[0047] In contrast, when displaying white, a predetermined voltage is applied to the liquid crystal layer 13 of the first liquid crystal panel 10, and the orientation of the liquid crystal molecules is S-polarized L S It forms a predetermined angle (for example, 45°) with respect to the vibration direction. In this state, the phase difference Δn·d of the liquid crystal layer 13 is set to approximately λ / 4, so as shown in Figure 3B, S-polarized light L incident on the first liquid crystal panel 10 S P-polarized L P It is converted and sent to PBS6. P-polarized light L is reflected from the first liquid crystal panel 10. P Since it passes through the polarization separation surface 6a of PBS6, it is projected onto the screen SC and appears as white.

[0048] Next, referring to Figures 4A and 4B, P-polarized L P This section explains the display using this method. Figures 4A and 4B show the black display state and the white display state, respectively.

[0049] As already explained, P-polarized L of the white light L emitted from light source 1 P However, it passes through the polarization separation surface 6a of PBS6 and heads toward the second liquid crystal panel 20. When displaying black, no voltage is applied to the liquid crystal layer 23 of the second liquid crystal panel 20, and the orientation of the liquid crystal molecules contained in the liquid crystal layer 23 is P-polarized L PThe direction of vibration is approximately parallel or perpendicular to it. Therefore, as shown in Figure 4A, the P-polarized light L incident on the second liquid crystal panel 20 P P-polarized L P It is reflected as is and heads towards PBS6. P-polarized light is reflected from the second liquid crystal panel 20. P Since it passes through the polarization separation surface 6a of PBS6, it is not projected onto the screen SC and appears as black.

[0050] In contrast, when displaying white, a predetermined voltage is applied to the liquid crystal layer 23 of the second liquid crystal panel 20, and the orientation of the liquid crystal molecules is P-polarized L P It forms a predetermined angle (e.g., 45°) with respect to the vibration direction. In this state, the phase difference Δn·d of the liquid crystal layer 23 is set to approximately λ / 4, so as shown in Figure 4B, P-polarized light L incident on the second liquid crystal panel 20 P S polarized L S It is converted and sent to PBS6. S-polarized light is reflected from the second liquid crystal panel 20. S This is reflected by the polarization separation surface 6a of PBS6, projected onto the screen SC, and displayed as white.

[0051] Next, the arrangement of subpixels in the liquid crystal projector 100 of this embodiment will be described.

[0052] Figure 5 shows the subpixel arrangement in the first liquid crystal panel 10 and the subpixel arrangement in the second liquid crystal panel 20 side by side. As shown in Figure 5, each pixel P in the first liquid crystal panel 10 and the second liquid crystal panel 20 is composed of a red subpixel R, a green subpixel G, and a blue subpixel B.

[0053] In the first liquid crystal panel 10, the pixels P are arranged in this order from the side corresponding to one end of the projected image to the side corresponding to the other end (along the +x axis in the figure). In contrast, in the second liquid crystal panel 20, the pixels P are arranged in this order from the side corresponding to one end of the projected image to the side corresponding to the other end (along the +y axis in the figure). In other words, the subpixel arrangement of the second liquid crystal panel 20 is the same as the subpixel arrangement of the first liquid crystal panel 10, but with the green subpixel G and blue subpixel B swapped.

[0054] For the sake of explanation, each subpixel of the first liquid crystal panel 10 will be referred to as a "first subpixel," and each subpixel of the second liquid crystal panel 20 will be referred to as a "second subpixel." Figure 6 shows the arrangement of the first subpixels SA10 and the arrangement of the second subpixels SA20 side by side in the projected image.

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

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

[0057] In this specification, among multiple types of subpixel sets, the subpixel set that yields the highest sum of the "luminance index values" of the colors of the first and second subpixels is referred to as the "first type of subpixel set," and the subpixel set that yields the lowest sum is referred to as the "second type of subpixel set." The "luminance index value" is a value that represents the luminance (brightness) of the color displayed by the subpixel, and is, for example, the Y value in the XYZ color system, but is not limited to this. Furthermore, the luminance index value may be an absolute value obtained by optical measurement, or it may be a relative value with respect to a certain reference value. Hereafter, the sum of the luminance index values ​​may also be referred to as the "luminance sum."

[0058] When a pixel P is composed of a red subpixel R, a green subpixel G, and a blue subpixel B, generally the luminance index value of the green subpixel G is the largest, and the luminance index value of the blue subpixel is the smallest (i.e., the luminance index value of the red subpixel R is between the luminance index value of the green subpixel G and the luminance index value of the blue subpixel). If the luminance index value is the Y value described above, and the Y value of white displayed by pixel P is 1, then the Y value of red displayed by the red subpixel R is, for example, about 0.25, the Y value of green displayed by the green subpixel G is, for example, about 0.63, and the Y value of blue displayed by the blue subpixel B is, for example, about 0.12. Therefore, in the liquid crystal projector 100 of this embodiment, the "first type of subpixel set" is a subpixel set that is a combination of the green subpixel G and the blue subpixel B, and the "second type of subpixel set" is a subpixel set that is a combination of two red subpixels R.

[0059] The liquid crystal projector 100 of this embodiment, having the configuration described above, can suppress the visibility of line-shaped light and dark areas in the projected image. The reason for this will be explained below in comparison with the comparative example liquid crystal projector 900 shown in Figure 7.

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

[0061] Referring to Figure 8, the arrangement of subpixels in the comparative example liquid crystal projector 900 will be explained. Figure 8 is a diagram showing the subpixel arrangement in the first liquid crystal panel 10 and the subpixel arrangement in the second liquid crystal panel 920 of the comparative example liquid crystal projector 900 side by side.

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

[0063] Figure 9 shows the arrangement of the first subpixel SA10 and the arrangement of the second subpixel SA920 in the projected image of the comparative example liquid crystal projector 900.

[0064] As can be seen from Figure 9, each pixel in the projected image (a composite of the projected image of the first liquid crystal panel 10 and the projected image of the second liquid crystal panel 920) is composed of: [4] a subpixel defined by the red subpixel R of the first liquid crystal panel 10 and the red subpixel R of the second liquid crystal panel 920; [5] a subpixel defined by the green subpixel G of the first liquid crystal panel 10 and the green subpixel G of the second liquid crystal panel 920; and [6] a subpixel defined by the blue subpixel B of the first liquid crystal panel 10 and the blue subpixel B of the second liquid crystal panel 20.

[0065] In the comparative example liquid crystal projector 900, there are multiple types of subpixel sets in which the color combinations of the first subpixel and the second subpixel differ from each other. Specifically, there are subpixel sets consisting of combinations of red subpixels R (subpixel sets that define the subpixels in [4] above in the projected image), subpixel sets consisting of combinations of green subpixels G (subpixel sets that define the subpixels in [5] above in the projected image), and subpixel sets consisting of combinations of blue subpixels B (subpixel sets that define the subpixels in [6] above in the projected image).

[0066] In the comparative example LCD projector 900, the "Type 1 subpixel set" is a subpixel set consisting of combinations of green subpixels G, and the "Type 2 subpixel set" is a subpixel set consisting of combinations of blue subpixels B.

[0067] In the comparative example liquid crystal projector 900 having the configuration described above, there is a concern that line-shaped areas of light and dark (sujimura) may be visible in the projected image. This is due to the large sum of luminance of the first type of subpixel set, and furthermore, the large difference between the sum of luminance of the first type of subpixel set and the sum of luminance of the second type of subpixel set. In direct-view liquid crystal display devices, the pixel size is set so that sujimura is not visible to humans, but in liquid crystal projectors, the image displayed on the liquid crystal panel is enlarged and projected, resulting in a pixel size that allows humans to see sujimura.

[0068] In contrast, the liquid crystal projector 100 of this embodiment has a smaller sum of luminance of the first type of subpixel set compared to the liquid crystal projector 900 of the comparative example. In terms of the exemplified Y value, the sum of luminance of the first type of subpixel set is approximately 1.26 for the liquid crystal projector 900 of the comparative example, while it is approximately 0.75 for the liquid crystal projector 100 of this embodiment. Therefore, the visibility of line-like brightness and darkness in the projected image is suppressed. Furthermore, the liquid crystal projector 100 of this embodiment has a smaller difference between the sum of luminance of the first type of subpixel set and the sum of luminance of the second type of subpixel set compared to the liquid crystal projector 900 of the comparative example. In terms of the exemplified Y value, the difference between the sum of luminance of the first type of subpixel set and the sum of luminance of the second type of subpixel set is approximately 1.02 for the liquid crystal projector 900 of the comparative example, while it is approximately 0.25 for the liquid crystal projector 100 of this embodiment. This also suppresses the visibility of line-like brightness and darkness in the projected image.

[0069] Thus, in the liquid crystal projector 100 of this embodiment, the color combinations of the first and second subpixels of each of the multiple types of subpixel sets are set such that the sum of the luminances of the first type of subpixel set is smaller than when it is assumed that the colors of the first and second subpixels are the same for each of the multiple types of subpixel sets (corresponding to the configuration of the comparative example liquid crystal projector 900). Furthermore, in the liquid crystal projector 100 of this embodiment, the color combinations of the first and second subpixels of each of the multiple types of subpixel sets are set such that the difference between the sum of the luminances of the first type of subpixel set and the sum of the luminances of the second type of subpixel set is smaller than when it is assumed that the colors of the first and second subpixels are the same for each of the multiple types of subpixel sets (corresponding to the configuration of the comparative example liquid crystal projector 900).

[0070] Here, we describe the results of verifying whether or not linear light and dark patterns (sujimura) were visible, using the comparative example liquid crystal projector 900 and the liquid crystal projector 100 of this embodiment (the prototype liquid crystal projector 100 will be referred to as the "example" below).

[0071] For the prototype, a ROHM LED (product name: MSL0402RGBU) was used as light source 1, and an Edmund polarizing beam splitter (product name: broadband cube-type polarizing B / S VIS) was used as PBS6. In addition, 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-type liquid crystal material, and the orientation in the voltage-free state was set to S-polarizing L S or P polarized L P The direction of vibration was set to be approximately parallel to the direction of vibration. Furthermore, the cell thickness was set so that the phase difference Δn·d of the liquid crystal layer when a white display voltage is applied is 140 nm.

[0072] The in-plane uniformity of the projected image formed on the screen SC was visually compared and evaluated for both the comparative example and the example. As a result, unevenness was visible in the comparative example, but no unevenness was visible in the example, indicating higher in-plane uniformity. Thus, it was confirmed that the visibility of line-like light and dark areas in the projected image was suppressed in the example.

[0073] Figure 10, like Figure 6, shows the arrangement of the first subpixel SA10 and the arrangement of the second subpixel SA20 in the projected image side by side, but it also shows the relative magnitudes of the Y values ​​of red, green, and blue, as well as the brightness and darkness when a white display is projected by the first liquid crystal panel 10 and when a white display is projected by the second liquid crystal panel 20.

[0074] As can be seen from Figure 10, the linear brightness and darkness in the image projected from the display of the first liquid crystal panel 10 and the linear brightness and darkness in the image projected from the display of the second liquid crystal panel 20 are inversely related. Therefore, the combined image of the two (the final projected image) exhibits high in-plane uniformity.

[0075] Thus, in the liquid crystal projector 100 of this embodiment, the visibility of line-shaped areas of light and dark in the projected image is suppressed.

[0076] Note that the arrangement of subpixels in each pixel P is not limited to the example shown in Figure 5. In the example shown in Figure 5, in each pixel of the first liquid crystal panel 10, the red subpixel R, green subpixel G, and blue subpixel B are arranged in this order from the side corresponding to one end of the projected image to the side corresponding to the other end, and in each pixel P of the second liquid crystal panel 10, the red subpixel R, blue subpixel B, and green subpixel G are arranged in this order from the side corresponding to one end of the projected image to the side corresponding to the other end.

[0077] In contrast, for example, the subpixel arrangement shown in Figure 11 may be adopted. In the example shown in Figure 11, in each pixel P of the first liquid crystal panel 10, the green subpixel G, red subpixel R, and blue subpixel B are arranged in this order from the side corresponding to one end of the projected image to the side corresponding to the other end, and in each pixel P of the second liquid crystal panel 20, the blue subpixel B, red subpixel R, and green subpixel G are arranged in this order from the side corresponding to one end of the projected image to the side corresponding to the other end. Even when the subpixel arrangement shown in Figure 11 is adopted, the same effect as when the subpixel arrangement shown in Figure 5 is adopted can be obtained.

[0078] Furthermore, while the explanation above has shown an example where each pixel P is composed of three subpixels—a red subpixel R, a green subpixel G, and a blue subpixel B—the number of subpixels and the color combinations that make up pixel P are not limited to this example.

[0079] A first type of subpixel set may be, for example, a combination of a subpixel of a first color with the highest luminance index value among multiple subpixels, and a subpixel of a second color with the lowest luminance index value. A second type of subpixel set may be a combination of subpixels of a third color that is different from the first and second colors.

[0080] Furthermore, a first type of subpixel set could be, for example, a combination of the subpixel with the largest Y value and the subpixel with the smallest Y value among a group of subpixels.

[0081] From the viewpoint of improving light utilization efficiency and color reproduction, it is preferable that the light source 1 has emission spectral peaks in the wavelength ranges corresponding to red, green, and blue, respectively.

[0082] From the viewpoint of reducing costs by omitting the phase difference plate, the display mode of the first liquid crystal panel 10 and the second liquid crystal panel 20 is preferably the horizontal orientation mode. In the horizontal orientation mode, the orientation of the homogeneously oriented liquid crystal molecules in the no-voltage state is S-polarized L S or P polarized L PA configuration can be suitably adopted in which the vibration direction is approximately parallel to the direction of vibration and the phase difference Δn·d of the liquid crystal layers 13 and 23 is approximately λ / 4 when a predetermined voltage (specifically, the white display voltage) is applied. Here, "the phase difference Δn·d is approximately λ / 4" means that the λ / 4 condition is substantially satisfied for visible light with a wavelength of 550 nm (for example, Δn·d is within the range of 137.5 ± 10 nm). [Industrial applicability]

[0083] According to embodiments 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, the visibility of line-shaped areas of brightness and darkness in the projected image can be suppressed. [Explanation of Symbols]

[0084] 1 light source 6. Polarizing Beam Splitter (PBS) 6a Polarization separation plane 10. First reflective liquid crystal panel (first liquid crystal panel) 11, 21 Active matrix substrate 11a, 21a, 12a, 22a substrates 12, 22 Opposing substrate 13, 23 Liquid crystal layer 14, 24 pixel electrodes 15, 25 First orientation film 16, 26 color filter layers 16R, 26R Red Color Filters 16G, 26G Green Color Filter 16B, 26B blue color filter 20. Second type of reflective liquid crystal panel (second liquid crystal panel) 31, 32 Convex lenses 100 LCD Projectors L white light L S S-polarized light L P P polarized light SC Screen P pixels R (Red subpixel) G Green subpixel B Blue subpixel

Claims

1. A light source that emits white light, A polarization beam splitter that separates the white light emitted from the light source into S-polarized and P-polarized light, A first reflective liquid crystal panel arranged to receive the aforementioned S-polarized light, A second reflective liquid crystal panel arranged to receive the P-polarized light, Equipped with, Each of the first reflective liquid crystal panel and the second reflective liquid crystal panel has a color filter layer and a plurality of pixels. Each of the aforementioned plurality of pixels includes a plurality of subpixels of different colors, A liquid crystal projector in which 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, When each subpixel of the first reflective liquid crystal panel is called a first subpixel, and each subpixel of the second reflective liquid crystal panel is called a second subpixel, and when a combination of the first subpixel and the second subpixel corresponding to the same subpixel in the projected image is called a subpixel set, There are multiple types of subpixel sets in which the color combinations of the first subpixel and the second subpixel are different from each other. When, among the multiple types of subpixel sets, the subpixel set whose sum of the luminance index values ​​of the first subpixel and the second subpixel is maximized is called the first type of subpixel set, A liquid crystal projector in which the color combinations of the first subpixel and the second subpixel of each of the multiple types of subpixel sets are set such that the total value of the first type of subpixel set is smaller than the value when it is assumed that the colors of the first subpixel and the second subpixel are the same for each of the multiple types of subpixel sets.

2. When, among the multiple types of subpixel sets mentioned above, the subpixel set that has the smallest total value is called the second type of subpixel set, The liquid crystal projector according to claim 1, wherein the color combinations of the first subpixel and the second subpixel of each of the multiple types of subpixel sets are set such that the difference between the total value of the first type of subpixel set and the total value of the second type of subpixel set is smaller than the difference when it is assumed that the colors of the first subpixel and the second subpixel are the same for each of the multiple types of subpixel sets.

3. The liquid crystal projector according to claim 1 or 2, wherein the first subpixel set is a combination of a subpixel of a first color having the maximum luminance index value and a subpixel of a second color having the minimum luminance index value among the plurality of subpixels.

4. The plurality of subpixels include a subpixel of the first color, a subpixel of the second color, and a subpixel of the third color. The liquid crystal projector according to claim 3, wherein the second type of subpixel set is a combination of the subpixels of the third color.

5. The liquid crystal projector according to claim 1 or 2, wherein the first subpixel set is a combination of the subpixel of the color with the largest Y value in the XYZ color system and the subpixel of the color with the smallest Y value among the plurality of subpixels.

6. Each of the aforementioned plurality of pixels includes a red subpixel, a green subpixel, and a blue subpixel. The liquid crystal projector according to claim 1 or 2, wherein the plurality of subpixel sets include a subpixel set which is a combination of the red subpixels and a subpixel set which is a combination of the green subpixels and the blue subpixels.

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

8. The liquid crystal projector according to claim 1 or 2, further comprising a projection optical system for magnifying and projecting 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 emission spectrum peaks in wavelength ranges corresponding to red, green, and blue, respectively.

10. Each of the first reflective liquid crystal panel and the second reflective liquid crystal panel has a liquid crystal layer, The liquid crystal molecules contained in the liquid crystal layer are homogeneously oriented in the absence of applied voltage. The orientation of the homogeneously oriented liquid crystal molecules is substantially parallel to the vibration direction of the S-polarized or P-polarized light. The liquid crystal projector according to claim 1 or 2, wherein the phase difference Δn・d of the liquid crystal layer is approximately λ / 4 when a predetermined voltage is applied.

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