JP5097371B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device used for a liquid crystal projector and the like, and more particularly to a liquid crystal display device capable of preventing a reduction in contrast ratio.

  In general, a liquid crystal panel used in a liquid crystal projector has a very small pixel size compared to a normal personal computer or television monitor. For this reason, a phenomenon occurs in which the diffraction angle when the projected light is diffracted at the edge of the light transmitting portion and the non-transmitting portion of each pixel is large and the amount of diffraction is large.

  Here, the contrast ratio (CR: Contrast Ratio) of the displayed image is defined by the luminance ratio of white display and black display. In white display, since the amount of transmitted light is large, the light is hardly affected by diffraction at the edge of the light transmission part and non-transmission part of the pixel, but in black display, it is arranged in front of the light traveling direction. Light is diffracted between the polarizing element and the polarizing element disposed at the rear at the edge of the light transmitting portion and the non-transmitting portion of the pixel. Then, the light traveling direction and the polarization direction change between the two polarizing elements, and as a result, light leakage occurs and the luminance increases. For this reason, there is a drawback that the CR of the displayed image is lowered.

  In addition, the liquid crystal panel adjusts the amount of transmitted light by controlling the alignment direction of the liquid crystal molecules by voltage. However, since the alignment speed of the liquid crystal molecules is slow, the operation speed is faster than other types of displays (CRT, etc.). Slow and generally inferior in performance to display moving images.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid crystal display device capable of preventing a decrease in CR by eliminating light diffraction and capable of high-speed operation. is there.

The above object of the present invention is achieved by the following configurations.
(1) an image display member that diffracts incident light;
An imaging member that condenses the diffracted light diffracted by the image display member;
An optical element that synthesizes the light collected by the imaging member, and a liquid crystal display device comprising:
The image display member is a liquid crystal panel having a predetermined pixel arrangement, and the optical element is a pixel structure filter having a light-transmissive substrate and a pixel layer corresponding to the image display member, and the pixel layer Has a pixel array that is point-symmetric with respect to the pixel array of the liquid crystal panel .
(2) The liquid crystal display device as described in (1) above, wherein the imaging member is a lens or a mirror.
( 3 ) The liquid crystal display device as described in 1 or 2 above, wherein polarizing elements are respectively provided on the light incident side and the light emitting side of the optical element with respect to the image display member.
(4) the image display member, a liquid crystal display device according to any one of the above 1 to 3, characterized in that it comprises a liquid crystal layer formed on the substrate.
(5) the coupling member is a pair of lenses, one lens into parallel light diffracted light, from the 1 other lens is characterized by condensing the parallel light to the optical element 4 The liquid crystal display device according to any one of the above.
( 6 ) a first image display member that diffracts incident light;
An imaging member that collects the diffracted light diffracted by the first image display member;
A second image display member that synthesizes the light collected by the imaging member, and a liquid crystal display device comprising:
The first image display member and the second image display member each have a predetermined pixel arrangement, and the liquid crystal panel includes a light transmissive panel substrate and a liquid crystal layer formed on the panel substrate. When, and a pixel layer, the pixel layer of said second image display member, have a pixel array which is point symmetrical with respect to the pixel arrangement of the pixel layer of the first image display member, the incident A liquid crystal display device characterized in that each of the liquid crystal panels has a half phase difference applied to light .
(7) The liquid crystal display device according to the 6, wherein the imaging member is a lens or mirror.
( 8 ) The liquid crystal as described in 6 or 7 above, wherein polarizing elements are respectively provided on the light incident side and the light emitting side of the second image display member with respect to the first image display member. Display device.
(9) The liquid crystal display according to any one of the 6 8, characterized in that said liquid crystal layer of the first image display member is formed on the light incident side of the pixel layer in the panel substrate apparatus.
(10) The liquid crystal display according to any one of the 6 9, characterized in that said liquid crystal layer of the second image display member is formed on the light emitting side of the pixel layer in the panel substrate apparatus.
(11) the coupling member is a pair of lenses, one lens into parallel light diffracted light, from the 6 to the other lens is characterized by condensing the parallel light to the optical element 10 of the The liquid crystal display device according to any one of the above.

The liquid crystal display device according to the present invention has a configuration in which light is diffracted by an image display member and then combined with an optical element by an imaging member, and the optical element is positioned optically conjugate with the pixel arrangement of the image display member. However, the pixel array of the image display member is configured to be symmetric with respect to the pixel array. In this way, the incident light can be once diffracted by the image display member and synthesized again with the optical element by the image forming member, thereby preventing diffraction. For this reason, since the advancing direction and polarization direction of incident light and outgoing light do not change, it is possible to prevent light from leaking and increasing luminance. Therefore, it is possible to prevent the CR of the displayed image from being lowered.
Further, by using each of the first image display member and the second image display member as a liquid crystal panel, the load per liquid crystal panel can be reduced to half and the operation speed can be increased. As a result, it is possible to operate twice as fast with simple calculation. Specifically, the phase difference given to the incident light only needs to be halved for each liquid crystal panel, and accordingly, the alignment control amount of the liquid crystal molecules can be halved, resulting in high-speed operation. .

  According to the present invention, it is possible to provide a liquid crystal display device capable of preventing a decrease in CR by eliminating light diffraction and capable of high-speed operation.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1A is a diagram for explaining a first embodiment of a liquid crystal display device according to the present invention, and FIG. 1B is a diagram showing a pixel arrangement structure of an image display member, and FIG. ) Is a diagram showing a pixel arrangement structure of optical elements. 1B shows a state in which the pixel display member is viewed in plan from the imaging member side, and FIG. 1C shows a state in which the optical element is viewed in plan from the side opposite to the imaging member side. ing.

  The liquid crystal display device 10 of this embodiment is used for a liquid crystal projector, for example. As shown in FIG. 1A, the liquid crystal display device 10 includes an image display member 11 that diffracts incident light Lin, imaging members 13a and 13b that collect diffracted light diffracted by the image display member 11, And an optical element 12 that synthesizes the light condensed by the imaging members 13a and 13b.

  In the present embodiment, the coupling members 13a and 13b are a pair of lenses, one lens 13a makes the diffracted light parallel light, and the other lens 13b condenses the parallel light on the optical element 12. When the distance between the image display member 11 and the one lens 13a and the distance between the other lens 13b and the optical element 12 are f, the distance between the lenses 13a and 13b is 2f. By doing so, the diffracted light can be appropriately condensed on the optical element 12.

  In the liquid crystal display device 10, the polarizing element 14 may be formed on the light incident side with respect to the image display member 11. Further, the polarizing element 15 may be formed on the light emitting side of the optical element 12.

  In the present embodiment, a liquid crystal panel is used as the image display member 11. As shown in FIG. 1B, the image display member 11 includes a panel substrate 11a having light transmittance, and a pixel layer 21 is formed on the panel substrate 11a. The pixel layer 21 has a predetermined pixel arrangement.

  FIG. 2 is a diagram illustrating a configuration of the image display member. As shown in FIG. 2, a liquid crystal layer 23 is formed on the panel substrate 11 a of the image display member 11 together with the pixel layer 21. Here, the liquid crystal layer 23 is formed on the light incident side from the pixel layer 21. By doing so, it is possible to avoid that light is not properly combined in the optical element 12 due to a change in the phase of light when the incident light Lin is diffracted and then passed through the liquid crystal layer 23.

  The imaging members 13a and 13b are diffracted lights (in FIG. 1, primary lights L1 and 2 in FIG. 1) of each wavelength of incident light Lin diffracted from light (0th order light L0 in FIG. 1) that travels straight by the image display member 11. It has the function of condensing the next light L2) onto the optical element 12. Lenses or mirrors can be used as the imaging members 13a and 13b.

  FIG. 3 is a diagram showing a configuration of the optical element. As shown in FIGS. 1C and 3, the optical element 12 has a function of again synthesizing the diffracted lights (L1 to L3) collected by the imaging member 13b. In the case of a liquid crystal projector, the light Lout synthesized by the optical element 12 is guided to a projector lens and projected onto a screen.

As the optical element 12, a pixel structure filter having a light-transmitting substrate 12 a and a pixel layer 22 having a predetermined pixel arrangement is used. The optical element 12 has a pixel array that is point-symmetric with respect to the pixel array of the image display member 11. Specifically, as shown in FIGS. 1B and 1C, the coordinates of one pixel in the pixel array in a state where the optical element 12 is viewed from the opposite side to the imaging members 13a and 13b side, This corresponds to the coordinates on the pixel array in a state in which the image display member 11 is viewed from the imaging members 13a and 13b in a state where the image display member 11 is rotated 180 ° from the center coordinates of the pixel array. In other words, the x1-axis direction of the pixel array of the pixel display member 11 shown in FIG. 1B corresponds to the x2-axis direction of the pixel array of the optical element 12 shown in FIG. The y1-axis direction of the pixel array corresponds to the y2-axis direction of the pixel array of the optical element 12 shown in FIG.

  In the present embodiment, the positional relationship between the distance between the image display member 11 and the imaging member 13 a and the distance between the imaging member 13 b and the optical element 12 synthesizes the diffracted light of the image display member 11 with the optical element 12. Are arranged so as to have an optically conjugate relationship.

  The liquid crystal display device 10 according to the present invention has a configuration in which light is diffracted by the image display member 11 and then combined with the optical element 12 by the imaging members 13 a and 13 b, and the optical element 12 is a pixel of the image display member 11. The position is optically conjugate with the arrangement, and the pixel arrangement is point-symmetric with the pixel arrangement of the image display member 11. In this manner, the incident light is once diffracted by the image display member 11 and again synthesized with the optical element 12 by the imaging members 13a and 13b, whereby diffraction can be prevented. For this reason, since the traveling direction and the polarization direction of the incident light Lin and the outgoing light Lout do not change, it is possible to prevent the light from leaking and increasing the luminance. Therefore, it is possible to prevent the CR of the displayed image from being lowered.

Next, examples of the liquid crystal display device according to the present embodiment will be described.
In the liquid crystal display device of this embodiment, a liquid crystal panel having a pixel pitch d of 25 μm is used as an image display member, the ± first-order diffraction angle of wavelength λ = 550 nm is ± 1.26 °, and the rotation to the ± 3rd-order. The folding angle was ± 3.78 °. As an imaging member, a lens with a focal length f = 50 mm covering a range of ± 14 ° (a diameter of 50 mm or more is desirable in consideration of the spread of the light incident angle to the liquid crystal panel (about ± 10 °). But you can use it.) The distance between the liquid crystal panel and the lens was 100 mm, and the distance between the lens and the pixel structure filter was 100 mm. Then, the light diffracted by the liquid crystal panel was condensed by a lens onto a pixel structure filter, which is an optical element, and synthesized by the reverse process of diffraction. According to this example, it was possible to prevent a decrease in CR.

The diffraction angle θ can be expressed as θ = sin ⁻¹ (mλ / d). Here, dsinθ = mλ, m is the diffraction order, d is the pixel interval, and λ is the wavelength.

    Next, a second embodiment of the liquid crystal display device according to the present invention will be described. In the embodiments described below, members having the same configuration / action as those already described are denoted by the same or corresponding reference numerals in the drawings, and description thereof is simplified or omitted.

  FIG. 4A is a diagram for explaining a second embodiment of the liquid crystal display device according to the present invention, and FIG. 4B is a diagram showing a pixel arrangement structure of the first image display member. FIG. 4C is a diagram illustrating a pixel arrangement structure of the second image display member. 4B shows a state in which the first pixel display member is viewed in plan from the imaging member side, and FIG. 4C is a plan view in which the second image display member is viewed from the imaging member side. Indicates the state.

  The liquid crystal display device 20 of this embodiment is used for a liquid crystal projector, for example. As shown in FIG. 4A, the liquid crystal display device 20 includes a first image display member 11 that diffracts incident light Lin, and an image that condenses the diffracted light diffracted by the first image display member 11. The members 13a and 13b and the second image display member 32 that synthesizes the light collected by the imaging members 13a and 13b are provided.

  The liquid crystal display device 20 may form the polarizing element 14 on the light incident side with respect to the first image display member 11. Further, the polarizing element 15 may be formed on the light emitting side of the second image display member 32.

  In the present embodiment, a liquid crystal panel is used as the first image display member 11. As shown in FIG. 4B, the first image display member 11 includes a panel substrate 11a having optical transparency, and a pixel layer 21 is formed on the panel substrate 11a. The pixel layer 21 has a predetermined pixel arrangement.

  FIG. 5 is a diagram illustrating a configuration of the first image display member. As shown in FIG. 5, a liquid crystal layer 23 is formed on the panel substrate 11 a of the first image display member 11 together with the pixel layer 21. Here, the liquid crystal layer 23 is formed on the light incident side from the pixel layer 21. By doing so, it is avoided that the light is not properly combined in the second image display member 32 due to a change in the phase of the light when passing through the liquid crystal layer 23 after the incident light Lin is diffracted. be able to.

  The imaging members 13a and 13b are diffracted lights (in FIG. 4, primary light in FIG. 4) of incident light Lin diffracted from light (0th order light L0 in FIG. 4) that travels straight by the first image display member 11. L1, secondary light L2) has a function of condensing on the optical element 32. Lenses or mirrors can be used as the imaging members 13a and 13b.

  FIG. 6 is a diagram illustrating a configuration of the second image display member. As shown in FIGS. 4C and 6, the second image display member 32 has a function of synthesizing again the diffracted lights (L1 to L2) collected by the imaging member 13b. In the case of a liquid crystal projector, the light Lout synthesized by the second image display member 32 is guided to a projector lens and projected onto a screen.

  As the second image display member 32, a liquid crystal panel having the same configuration as the first image display member 11 can be used. The second image display member 32 includes a pixel layer 42 disposed on the panel substrate 32a on the coupling member 13b side, and a liquid crystal layer 45 disposed on the side from which the synthesized light Lout is emitted. The second image display member 32 has a pixel array that is point-symmetric with respect to the pixel array of the first image display member 11. Specifically, as shown in FIGS. 4B and 4C, the coordinates of one pixel in the pixel array in a state where the second image display member 32 is viewed in plan from the imaging members 13a and 13b side, This corresponds to the coordinates on the pixel array in a state where the first image display member 11 is viewed from the imaging members 13a and 13b in a state where the first image display member 11 is rotated 180 ° from the center coordinates of the pixel array. In other words, the x1 axis direction of the pixel array of the first pixel display member 11 shown in FIG. 4B is in the x2 axis direction of the pixel array of the second image display member 32 shown in FIG. The y1 axis direction of the pixel array of the first pixel display member 11 corresponds to the y2 axis direction of the pixel array of the second image display member 32 shown in FIG.

  In the present embodiment, the positional relationship between the distance f between the first image display member 11 and the imaging member 13a and the distance f between the imaging member 13b and the second image display member 32 is the first image display member. 11 diffracted lights are arranged so as to have an optically conjugate relationship so that the second image display member 32 can synthesize them.

The liquid crystal display device 20 according to the present invention has a configuration in which light is diffracted by the first image display member 11 and then combined with the second image display member 32 by the imaging members 13a and 13b. The display member 32 is configured so as to be a pixel array that is optically conjugate with the pixel array of the first image display member 11 and is point-symmetric with the pixel array of the first image display member 11. Yes. In this way, the incident light is once diffracted by the first image display member 11 and synthesized again with the second image display member 32 by the imaging members 13a and 13b, whereby diffraction can be prevented. For this reason, since the traveling direction and the polarization direction of the incident light Lin and the outgoing light Lout do not change, it is possible to prevent the light from leaking and increasing the luminance. Therefore, it is possible to prevent the CR of the displayed image from being lowered.
Further, by making each of the first image display member 11 and the second image display member 32 a liquid crystal panel, the burden per liquid crystal panel can be reduced by half, and the operation speed can be increased. As a result, it is possible to operate twice as fast with simple calculation. Specifically, the phase difference given to the incident light only needs to be halved for each liquid crystal panel, and accordingly, the alignment control amount of the liquid crystal molecules can be halved, resulting in high-speed operation. .

Next, examples of the liquid crystal display device according to the present embodiment will be described.
In the liquid crystal display device of this embodiment, a liquid crystal panel having a pixel pitch d of 25 μm is used as the first image display member and the second image display member, respectively, and ± 1st order diffraction angle of wavelength λ = 550 nm is ± 1. The diffraction angle up to ± 3rd order was ± 3.78 °. As an imaging member, a lens with a focal length f = 50 mm covering a range of ± 14 ° (a diameter of 50 mm or more is desirable in consideration of the spread of the light incident angle to the liquid crystal panel (about ± 10 °). But you can use it.) The distance between the liquid crystal panel and the lens was 100 mm, and the distance between the lens and the pixel structure filter was 100 mm. Then, the light diffracted by the liquid crystal panel was condensed by a lens onto a pixel structure filter, which is an optical element, and synthesized by the reverse process of diffraction. According to this example, it was possible to prevent a decrease in CR.

The diffraction angle θ can be expressed as θ = sin ⁻¹ (mλ / d). Here, dsinθ = mλ, m is the diffraction order, d is the pixel interval, and λ is the wavelength.

In addition, as an example of moving image display in the present embodiment, a process when converting from black display to white display will be described.
FIG. 7 is a graph showing the relationship between the voltage (V) applied for controlling the alignment of liquid crystal molecules and the phase difference (retardation Re) applied to light in moving image display. As shown in FIG. 7, during black display, the phase difference given to the light by the liquid crystal layer is 0, but during white display, a predetermined voltage V ₁ is applied to set the phase difference to λ / 2. become. In this method, it is sufficient to control the voltage to a predetermined voltage V ₂ to give a phase difference of λ / 4 per liquid crystal layer. Since the amount of orientation is also halved, it can be operated faster.

In addition, this invention is not limited to embodiment mentioned above, A suitable deformation | transformation, improvement, etc. are possible.
As the optical element, the same member as the image display member, for example, a liquid crystal panel having the same pixel arrangement can be used. However, the cost of components can be reduced by using a pixel structure filter as the optical element.
In the first embodiment, the arrangement of the image display member and the optical element may be interchanged.

(A) is a figure explaining the liquid crystal display device of 1st Embodiment, (b) is a figure which shows the pixel arrangement structure of an image display member, (c) is a figure which shows the pixel arrangement structure of an optical element. It is. It is a figure which shows the structure of an image display member. It is a figure which shows the structure of an optical element. (A) is a figure explaining the liquid crystal display device of 2nd Embodiment, (b) is a figure which shows the pixel arrangement | sequence structure of a 1st image display member, (c) is a 2nd image display member. It is a figure which shows these pixel arrangement | sequence structures. It is a figure which shows the structure of a 1st image display member. It is a figure which shows the structure of a 2nd image display member. It is a graph which shows the relationship between voltage (V) and the phase difference (retardation Re) given to light.

Explanation of symbols

10, 20 Liquid crystal display device 11 Image display member (first image display member)
12 Optical elements 13a, 13b Imaging members 14, 15 Polarizing element 32 Second image display member

Claims (6)

A first image display member that diffracts incident light;
An imaging member that collects the diffracted light diffracted by the first image display member;
A second image display member that synthesizes the light collected by the imaging member, and a liquid crystal display device comprising:
The first image display member and the second image display member are luminance modulation liquid crystal panels each having a predetermined pixel arrangement, and the liquid crystal panel is formed on the light transmissive panel substrate and the panel substrate. A pixel arrangement having a liquid crystal layer and a pixel layer, wherein the pixel layer of the second image display member is point-symmetric with respect to the pixel arrangement of the pixel layer of the first image display member has,
A liquid crystal display device characterized in that each of the liquid crystal panels has a phase difference that is half of the phase difference given to incident light. The liquid crystal display device according to claim 1 , wherein the imaging member is a lens or a mirror. On the light emitting side of the first to the image display member and the light-incident side and the second image display member, the liquid crystal display device according to claim 1 or 2, characterized in that each provided a polarizing element . The liquid crystal display device according to any one of claims 1-3, wherein the liquid crystal layer of the first image display member is formed on the light incident side of the pixel layer in the panel board. The liquid crystal display device according to any one of the four claims 1, wherein the liquid crystal layer of the second image display member is formed on the light emitting side of the pixel layer in the panel board. A said coupling member is a pair of lenses, one lens into parallel light diffracted light, any one of claims 1 to 5 in which the other lens is characterized by condensing the parallel light to the optical element The liquid crystal display device according to one.

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