JP5846770B2 - Electrode structure of liquid crystal display panel and hologram recording apparatus - Google Patents

Description

  The present invention relates to an electrode structure of a liquid crystal display panel and a hologram recording apparatus using the same, and more particularly to a structure of a pixel electrode arranged for each pixel in order to apply a voltage to liquid crystal in the hologram recording apparatus. The present invention relates to an improvement in the electrode structure of a liquid crystal display panel in which signal information is carried by irradiation light in order to generate signal light for hologram recording.

  As a spatial light modulator for modulating data, a liquid crystal display panel used for a liquid crystal display or a projector is known. In these display liquid crystal display panels, one electrode is a common solid electrode, but the other electrode is independent for each pixel, so that a sufficient voltage can be applied to each pixel. The size is close to the contour.

  Further, as an electrode structure for improving the viewing angle of the display, a ring-shaped electrode structure as shown in Patent Document 1 is used. In this electrode structure, in order to apply a voltage in the horizontal direction, two electrodes, a common electrode and a pixel electrode, are combined in the same plane.

JP 2005-173541 A

  By the way, in hologram recording, the reproduction light on which the page data is superimposed is sampled and imaged by a CCD or the like.

  If the reproduction from the hologram is ideal, the luminance distribution of the imaged page data is the same as the luminance distribution of the light transmitted or reflected by the liquid crystal display panel, but the luminance distribution is the pixel structure of the liquid crystal display panel. Therefore, when a liquid crystal display panel for display is used, a rectangular wave shape that is continuous in both the vertical direction and the horizontal direction is obtained.

  FIG. 7 shows an example when the page data is modulated by the liquid crystal display panel. The highest spatial frequency is when light (132 in FIG. 7) and dark (131 in FIG. 7) alternate for each adjacent pixel. FIG. 8 shows the light intensity distribution and frequency characteristics on a horizontal line (X direction) in this case (broken line in FIG. 7). Since the light intensity distribution has a rectangular wave shape, harmonics are generated in the frequency component.

  In this case, if the repetition frequency of the page data is about half the sampling frequency at the time of imaging, harmonics exist near this sampling frequency, and the reproduced image becomes aliasing noise due to sampling. Appear in This lowers the SNR of the reproduction data, and is a big problem particularly in hologram recording where high-quality reproduction is expected.

The present invention has been made in view of such circumstances, and an electrode structure of a liquid crystal display panel for signal data modulation, and a hologram using the same, which can reduce aliasing noise caused by sampling of an image sensor during hologram reproduction An object is to provide a recording apparatus.

The electrode structure of another liquid crystal display panel of the present invention is
In a transmissive or reflective liquid crystal display panel, an electrode provided for each pixel, which is arranged on at least one of the electrodes for applying a voltage to the liquid crystal, is a circle centering on the center position of each pixel. A circular electrode portion having a shape, and a concentric electrode portion provided concentrically on the outer peripheral side of the circular electrode portion,
The concentric electrode part is composed of a plurality of concentric electrodes, and the distance between the circular electrode part and the concentric electrode part and the distance between the concentric electrodes become wider as the distance from the center of the pixel increases. It is characterized by being.

The hologram recording apparatus of the present invention is
Of the electrodes for applying a voltage to the liquid crystal, the electrode provided for each pixel disposed on at least one surface side is composed of a circular electrode having a circular shape centering on the center position of each pixel. Or a reflective LCD panel,
The liquid crystal display panel functions as a spatial light modulation element that carries image information in signal light when performing hologram recording.

In addition, another hologram recording apparatus of the present invention,
Of the electrodes for applying a voltage to the liquid crystal, the electrode provided for each pixel disposed on at least one surface side has a circular electrode portion having a circular shape with the center position for each pixel as a center, and this circle A transmissive or reflective liquid crystal display panel comprising a concentric electrode portion provided concentrically on the outer peripheral side of the shape electrode portion,
The liquid crystal display panel functions as a spatial light modulation element that carries image information in signal light when performing hologram recording.

Still another hologram recording apparatus of the present invention is
A liquid crystal display panel having the electrode structure of any of the liquid crystal display panels described above is provided,
The liquid crystal display panel, when performing hologram recording, and is characterized in that functions as a spatial light modulator allowed to carrying image information in the signal light.

  According to the electrode structure of the liquid crystal display panel according to the present invention, an electrode provided for each pixel that applies a voltage to the liquid crystal of the liquid crystal display panel is disposed at least on one surface side of the liquid crystal display panel. The area ratio occupied by the electrodes is configured so as to decrease as the distance from the center of each pixel increases. For each pixel, a sufficient voltage is applied to the center, but as it moves toward the periphery. Since voltage application becomes insufficient, the light intensity at the center is the highest for each pixel, and decreases toward the periphery.

  As a result, the light intensity distribution on the virtual line (horizontal or vertical straight line) of the liquid crystal display panel is not a continuous rectangular wave shape, but rather a sinusoidal, gently changing curve shape. It will be a thing.

  When the light intensity distribution of the page data is sinusoidal, the frequency component is a single component and no harmonics are generated. Therefore, no harmonics exist near the sampling frequency when the image is taken, and no aliasing noise occurs.

It is a figure which shows the light intensity distribution (B) of the page structure modulated by the electrode structure (A) of the liquid crystal display panel which concerns on Example 1 of this invention, and the liquid crystal display panel which concerns on Example 1. FIG. 3 shows page data modulated by a liquid crystal display panel used in the embodiment. FIG. 3 is a graph (A) showing a light intensity distribution in a pixel column on a broken line in FIG. 2 and a graph (B) showing a frequency characteristic in FIG. It is a figure which shows the light intensity distribution (B) of the page structure modulated by the electrode structure (A) of the liquid crystal display panel which concerns on Example 2 of this invention, and the liquid crystal display panel which concerns on Example 2. FIG. It is a figure which shows the light intensity distribution (B) of the page structure modulated with the electrode structure (A) of the liquid crystal display panel which concerns on Example 3 of this invention, and the liquid crystal display panel which concerns on Example 3. FIG. FIG. 2 is a schematic diagram (A) showing a configuration of an optical system of a hologram recording apparatus and a schematic diagram (B) showing a laminated structure of a liquid crystal display panel according to this example. This shows page data modulated by a liquid crystal display panel used in the prior art. 8 is a graph (A) showing the light intensity distribution in the pixel column on the broken line in FIG. 7 and a graph (B) showing the frequency characteristics in FIG. 8A.

In the embodiment of the present invention, the ratio of the area occupied by the transparent electrode on one side of the liquid crystal display panel in each pixel is configured to decrease from the center to the periphery of each pixel.
Hereinafter, this configuration will be described using three examples.

<Example 1>
FIG. 1A shows the shape of each pixel 41 and the shape of the transparent electrode 42 in the first embodiment. That is, each pixel 41 has a rectangular shape, and the transparent electrode 42 has a circular shape centered on the approximate center point of each pixel 41.

  In this embodiment, the electrode facing the transparent electrode 42 (common electrode 81A in FIG. 6B) has a flat plate shape that covers all pixels as a common electrode. Specifically, it will be described later with reference to FIG.

  In the present embodiment, a method is employed in which each pixel 41 is driven by a TFT, and is driven via a bus line 43A from the X driver 61 and a bus line 43B from the Y driver 62.

  The transparent electrode 42 (and the common electrode when the common electrode is also transparent) is formed of a transparent electrode using a material such as ITO. The bus lines 43A and 43B are preferably made of a highly conductive metal such as gold.

  FIG. 1A shows the shape (rectangular shape) of each pixel 41 and the shape (circular shape) of the transparent electrode 42, and is arranged on one side of the liquid crystal display panel (the front electrode in this embodiment). The area ratio of the arranged transparent electrode 42 in each pixel 41 is configured to decrease from the center of the pixel 41 toward the periphery.

  That is, the transparent electrode 42 in the present embodiment has a circular shape with the center position of each pixel 41 as the center, and is not disposed on the periphery of each pixel 41. Therefore, according to the electrode structure according to the first embodiment, the ratio of the electrodes disposed is large at the central portion and small at the outer peripheral portion.

  In the case of such an electrode structure, if a voltage is applied to the electrode of the pixel 41 so that the light intensity distribution of the page data is alternately bright and dark for each pixel, each of the X direction (horizontal direction; the same applies hereinafter) The light intensity distribution on the straight line passing through the pixel 41 is close to a sine wave as indicated by the solid curve in FIG. 1B (the broken line is an ideal sine wave curve for comparison). This is because, in the electrode structure, the area ratio of one transparent electrode 42 is set to be large at the center of each pixel 41 and to be small at the periphery, and a voltage is applied to the liquid crystal at the center of each pixel 41. Is sufficiently applied, but a voltage is not sufficiently applied to the liquid crystal in the peripheral portion of each pixel 41. In addition, in the intermediate portion of each pixel 41, the peripheral portion of the transparent electrode 42 according to the characteristics of the liquid crystal. Since the light intensity distribution does not rise or fall steeply in the vicinity but changes with a slight inclination, it has a shape close to a sine wave.

FIG. 2 shows the state of the two-dimensional light intensity distribution when predetermined page data is modulated by the liquid crystal display panel (the liquid crystal display panel 8 in FIG. 6A) when the electrode structure of this embodiment is used. It is shown.
On the broken line extending in the X direction shown in FIG. 2, the light intensity distribution is alternated between light and dark. In this case, the frequency is maximum, but the frequency is about half of the sampling frequency at the time of imaging. If it becomes the following value, aliasing noise does not occur and the SNR of the reproduced image does not deteriorate.

  On the other hand, for example, as shown in FIG. 7, when the page data is modulated by the liquid crystal display panel according to the prior art (the pixel electrode of the liquid crystal display panel is approximately equal to the rectangular outline of each pixel), Assuming that the black level pixels 131 and the white level pixels 132 are alternately arranged on the broken line extending in the X direction and the light intensity distribution is an alternating light intensity distribution, the light intensity distribution is a rectangular wave as shown in FIG. Since it has a shape and harmonics are generated, for example, as shown in FIG. 8B, harmonics are generated in the vicinity of the sampling frequency. For this reason, in the prior art, aliasing noise occurs and the SNR of the reproduced image is greatly degraded.

  In the present embodiment, the area ratio of each pixel electrode of the liquid crystal display panel is set so that the peripheral portion is smaller than the central portion. Therefore, by making the light intensity distribution a shape close to a sine wave, the frequency component is A substantially single frequency component can be obtained, and harmonics can be reduced.

  In each of the above embodiments, the other electrode (common electrode) has a common plate-like electrode structure. However, the common electrode is also configured in a circle corresponding to the transparent electrode 42 in FIG. Each may be connected by a bus line made of a conductive material such as gold.

  Hereinafter, a main optical system of a hologram recording apparatus (including a hologram recording / reproducing apparatus) according to an embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 6A, a coherent laser beam (for example, wavelength 532 nm) emitted from a laser light source (DPSS (Diode Pumping Solid State) laser light source) 1 is used as a beam expander and a spatial filter. After passing through the functioning spatial filter 2, passing through the half-wave plate 4 and reflected by the reflection mirror 5, it is branched into two light beams by the polarizing beam splitter 6, and each of the signal lights (object light: actually liquid crystal) The display panel 8 functions as signal light) and reference light. As described above, the point of this embodiment relates to the electrode structure of the liquid crystal display panel 8.

  The reference light passes through the shutter 20 for appropriately passing / blocking the light flux, is reflected by the reflection mirror 21, and is applied to a predetermined area on the hologram recording medium 101. The reflection mirror 21 is installed on a mounting table of a rotator 22 that is rotatable about a substantially central position of the mounting table as a rotation axis. Specifically, it is composed of a galvanometer mirror or the like.

On the other hand, the signal light is applied to the liquid crystal display panel 8 through the polarization beam splitter 7.
As the liquid crystal display panel 8, for example, a 0.7-type reflective liquid crystal display panel is suitable, but a transmissive liquid crystal display panel may be used. Each pixel on the liquid crystal display panel 8 spatially modulates light by changing the deflection direction of light according to binary digital information on page data. Signal light carrying page data information is generated by this modulation processing. The light intensity distribution of the signal light shown in FIG. 2 is such that page data information is represented by the modulation distribution for each pixel 41, and by devising the electrode shape of each pixel 41 as described above. The light intensity corresponding to the center of each pixel 41 is high, and the light intensity decreases toward the periphery, that is, close to a sine wave shape.

  The polarization direction of the signal light emitted from the liquid crystal display panel 8 changes from the incident state, is reflected by the polarization beam splitter 7, passes through the shutter 9, and is optically Fourier transformed by the first lens 10. Then, the hologram recording medium 101 is irradiated. At this time, since the reference light is simultaneously irradiated from another angle to the area irradiated with the signal light in the hologram recording medium 101, interference fringes are generated in the volume inside the hologram recording medium 101, and this fringe distribution is refracted. Hologram recording is performed by recording in a recording area of the hologram recording medium 101 in a form such as a rate distribution.

  Here, as the hologram recording medium 101, for example, a medium in which a photopolymer material having a thickness of 1 mm is sandwiched between two glass disks is used.

  Note that lenses 23 and 24 are disposed between the reflection mirror 21 and the hologram recording medium 101.

  Further, different page data is modulated in the hologram recording medium 101 by changing the incident angle of the reference light to the hologram recording medium 101 little by little using the rotator 22 while modulating the different page data on the liquid crystal display panel 8. Can be recorded in the same area, and information can be stored at higher density. It is to be noted that a rotation movement instruction for the rotator 22 and a straight line for a carriage means (not shown) for linearly moving the hologram recording medium 101 in the inner and outer peripheral directions, which is made to shift the recording area of the hologram recording medium 101. The movement instruction is performed using a control signal from the control unit 110.

  When information is reproduced from the hologram recording medium 101 after the information recording described above is performed, the reference light that has passed through the shutter 20 is set so as to satisfy a predetermined reference light incident condition. The predetermined area of the hologram recording medium 101 is irradiated. The shutter 9 is in a closed state.

  That is, when reproducing the desired page data, in principle, the reference light is made incident on the hologram recording medium 101 at the same incident angle and position as the information recording in which the desired page data is recorded. Reproduction light (diffracted light) carrying the page data information is output from the hologram recording medium 101, and this reproduction light is incident on the image sensor of the CCD camera 14 via the second lens 12 and imaged.

  Here, the reflective liquid crystal light modulator (liquid crystal display panel) 80 according to the present embodiment will be briefly described with reference to FIG.

  This liquid crystal light modulator 80 has a structure in which a liquid crystal layer 82 is sandwiched between transparent substrates 86 with transparent electrodes (common electrodes 81A, pixel electrodes 81B) provided with an alignment film 84. A reflecting plate 85 is provided to reflect the incident light 87.

  When the voltage from the power source 90 is applied between the common electrode 81A and the pixel electrode 81B via the wiring 89, the light modulation operation can be performed while the liquid crystal layer 82 is held between the two transparent substrates 86. . That is, the reflected light 88 is output in a state where the signal light information is carried with respect to the incident light 87.

  The initial alignment of the liquid crystal can be realized by selecting the alignment film 84 in various alignment states such as parallel alignment, vertical alignment, and twist alignment.

<Example 2>
An electrode structure according to Example 2 that can be used in place of the electrode structure according to Example 1 described above will be described with reference to FIG.

  The electrode structure according to the second embodiment includes a circular electrode portion 71A having a circular shape centering on the center position of each pixel 41, and a concentric electrode portion concentrically provided on the outer peripheral side of the circular electrode portion 71A. 72A. The concentric electrode portion 72A has a triple structure (not limited to triple, and may be single, double, or quadruple or more), and the interval between the concentric electrode portions 72A and the circular electrode portion 71A. And the concentric electrode portion 72A are set to be substantially equal to each other. In addition, the outer peripheral portion of the concentric electrode portion 72A is a region where no electrode is disposed. According to the electrode structure according to the second embodiment, the ratio of the electrodes arranged is large, medium, and small in the order of the central portion, the intermediate portion, and the outer peripheral portion, and according to this, the liquid crystal layer The voltage applied to is also decreased in the order of the central portion, the intermediate portion, and the outer peripheral portion. As a result, as shown in FIG. 4B, the light intensity distribution of the signal light modulated by each pixel 41 can be made closer to a sinusoidal waveform than in the case of the first embodiment, and the frequency component is substantially single. It can be a frequency component, and harmonics can be greatly reduced.

  The circular electrode portion 71A and each concentric electrode portion 72A are electrically connected to each other through a conductor pattern.

<Example 3>
Next, an electrode structure according to Example 3 that can be used in place of the electrode structures according to Example 1 and Example 2 described above will be described with reference to FIG.

  The electrode structure according to the third embodiment includes a circular electrode portion 71B having a circular shape centering on the center position of each pixel 41, and a concentric electrode portion concentrically provided on the outer peripheral side of the circular electrode portion 71B. 72B. As shown in FIG. 5A, the concentric electrode portions 72B have a triple structure (not limited to triple, and may be single, double, or quadruple or more), and each concentric electrode portion 72B. The width in the radial direction is set to become smaller toward the outer peripheral side than the inner peripheral side. In addition, although it is possible to set the space | interval of the radial direction of each concentric-shaped electrode part 72B to the thing of various magnitude | sizes, the ratio for which the electrode part 72B occupies decreased in the outer peripheral part compared with the center part. It is necessary to set.

  According to the electrode structure according to Example 3, the ratio of the electrodes disposed is large, medium, and small in the order of the central portion, the intermediate portion, and the outer peripheral portion. The width of the electrode is reduced as it goes from the peripheral side to the outer peripheral side, and the ratio of the electrodes is set so as to decrease as it goes toward the outer peripheral side. Accordingly, the applied voltage applied to the liquid crystal phase is also centered. It is set so that it decreases in order of the part, the intermediate part, and the outer peripheral part, and also decreases in the intermediate part as it approaches the outer peripheral part. As a result, as shown in FIG. 5B, the light intensity distribution of the signal light modulated by each pixel 41 can be made closer to a sinusoidal shape than in the case of the second embodiment, and the frequency component is substantially single. It can be a frequency component, and harmonics can be reduced more greatly. Further, the control accuracy of the liquid crystal display can be improved by adjusting the electrode width of the concentric electrode portion 72B.

  As in the second embodiment, the circular electrode portion 71B and each concentric electrode portion 72B are electrically connected to each other through a conductor pattern.

  In the technique described in Patent Document 1 described above, in order to widen the viewing angle of the display, two independent electrodes are developed in the same plane in a shape close to a concentric circle, and different voltages are applied. However, when this method is used, it is necessary to dispose the electrodes so as not to contact each other, and the difficulty of creation becomes extremely high as the liquid crystal display panel becomes high definition.

  On the other hand, since it is not required to widen the viewing angle in the hologram recording, it is not necessary to apply different voltages to a plurality of electrodes arranged in the same plane. There is no requirement to use technology.

  Note that the electrode structure of the liquid crystal display panel and the hologram recording apparatus according to the present invention are not limited to those of the above-described embodiments, and other various modifications can be made.

  For example, in Example 3 described above, the width of each concentric electrode constituting the concentric electrode portion 72B is arranged so as to decrease from the inner peripheral side toward the outer peripheral side. The distance between the electrodes may be arranged so as to increase from the inner peripheral side toward the outer peripheral side. The point is that the area ratio occupied by the electrodes in the concentric electrode portion 72B may be arranged so as to decrease from the central portion toward the outer peripheral portion of each pixel. You may make it combine both of change.

  Moreover, in each said Example, although the shape is devised about the electrode distribute | arranged to the one surface side among the electrodes which oppose, also about the electrode arrange | positioned to the other surface side, said one surface side It is good also as the shape similar to or the shape made to respond | correspond.

  In the above embodiment, a circular electrode is disposed at the center of each pixel, and if the electrode is circular, the manufacturability is improved, but this electrode shape is triangular, rectangular or pentagonal. It is also possible to use the above polygon.

  Moreover, it is possible to change each electrode shape of the concentric electrode part mentioned above according to the electrode shape of this center part.

  Furthermore, in the hologram recording apparatus of the present invention, the laser light source is not limited to the one exemplified in the above embodiment, and can be changed to one that outputs other wavelength light, for example, wavelength 405 nm That emit blue laser light can be used.

DESCRIPTION OF SYMBOLS 1 Laser light source 2 Spatial filter 4 Half wave plate 5,21 Mirror 6,7 Polarizing beam splitter 8 Liquid crystal display panel 9,20 Shutter 10,12,23,24 Lens 12 Rectangular opening 13 CCD camera 22 Rotator 31 Black level Pixel 32 White level pixel 41, 41A, 41B Pixel 42, 42A, 42B Transparent electrode 43, 43A, 43B Bus line 51 TFT
61 X driver 62 Y driver 71A, 71B Circular electrode portion 72A, 72B Concentric electrode portion 80 Liquid crystal light modulator 81A Common electrode 81B Pixel electrode 82 Liquid crystal layer 84 Alignment film 85 Reflector plate 86 Transparent substrate 87 Incident light 88 Reflected light 89 Wiring 90 Power supply 101 Hologram recording medium 110 Control means

Claims (4)

In a transmissive or reflective liquid crystal display panel, an electrode provided for each pixel, which is arranged on at least one of the electrodes for applying a voltage to the liquid crystal, is a circle centering on the center position of each pixel. A circular electrode portion having a shape, and a concentric electrode portion provided concentrically on the outer peripheral side of the circular electrode portion,
The concentric electrode part is composed of a plurality of concentric electrodes, and the distance between the circular electrode part and the concentric electrode part and the distance between the concentric electrodes become wider as the distance from the center of the pixel increases. An electrode structure of a liquid crystal display panel, wherein Of the electrodes for applying a voltage to the liquid crystal, the electrode provided for each pixel disposed on at least one surface side is composed of a circular electrode having a circular shape centering on the center position of each pixel. Or a reflective LCD panel,
The liquid crystal display panel functions as a spatial light modulation element that carries image information in signal light when performing hologram recording. Of the electrodes for applying a voltage to the liquid crystal, the electrode provided for each pixel disposed on at least one surface side has a circular electrode portion having a circular shape with the center position for each pixel as a center, and this circle A transmissive or reflective liquid crystal display panel comprising a concentric electrode portion provided concentrically on the outer peripheral side of the shape electrode portion,
The liquid crystal display panel functions as a spatial light modulation element that carries image information in signal light when performing hologram recording. A liquid crystal display panel having the electrode structure of the liquid crystal display panel according to claim 1 ,
A hologram recording apparatus, wherein the liquid crystal display panel functions as a spatial light modulation element that carries image information in signal light when performing hologram recording.