Active matrix display device
First Claim
Patent Images
1. An active matrix display device comprising:
- a pixel element;
a pixel element electrode disposed for the pixel element;
a plurality of sub-pixel element electrodes disposed for the pixel element electrode, each of the sub-pixel element electrodes having a different surface area, receiving an equal voltage according to an image signal in a moving picture display mode and receiving a respective bit signal of a digital image signal in a still picture display mode; and
a plurality of retaining circuits disposed for the pixel element electrode, each of the retaining circuits corresponding to one of the sub-pixel element electrodes, retaining a voltage, and supplying the voltage to the corresponding sub-pixel element electrode,wherein the sub-pixel element electrodes are symmetrically disposed with respect to a first line of symmetry passing substantially through a center of the pixel element, with respect to a second line of symmetry passing substantially through the center of the pixel element, or with respect to both the first line and the second line, the first line and the second line being substantially orthogonal to each other.
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Abstract
In the active matrix display device with a DRAM as the retaining circuit, the voltage retained in the retaining circuit is set in the brightness saturation region, which is outside the region of the voltage used in the moving picture display mode. With the voltage in this region, the difference in the brightness will not be recognized even if the voltage decreases before the refreshing operation. This prevents flickering and improves the display quality.
19 Citations
23 Claims
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1. An active matrix display device comprising:
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a pixel element; a pixel element electrode disposed for the pixel element; a plurality of sub-pixel element electrodes disposed for the pixel element electrode, each of the sub-pixel element electrodes having a different surface area, receiving an equal voltage according to an image signal in a moving picture display mode and receiving a respective bit signal of a digital image signal in a still picture display mode; and a plurality of retaining circuits disposed for the pixel element electrode, each of the retaining circuits corresponding to one of the sub-pixel element electrodes, retaining a voltage, and supplying the voltage to the corresponding sub-pixel element electrode, wherein the sub-pixel element electrodes are symmetrically disposed with respect to a first line of symmetry passing substantially through a center of the pixel element, with respect to a second line of symmetry passing substantially through the center of the pixel element, or with respect to both the first line and the second line, the first line and the second line being substantially orthogonal to each other. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An active matrix display device comprising:
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a first substrate and a second substrate; a liquid crystal disposed between the first substrate and the second substrate; a plurality of pixel element electrodes disposed on the first substrate; a plurality of retaining circuits disposed on the first substrate, the retaining circuits corresponding to the pixel element electrodes, each of the retaining circuits retaining a voltage, the voltages retained by the retaining circuits being supplied to the corresponding pixel element electrodes to form an image; a plurality of sub-pixel element electrodes provided for each of the pixel element electrodes, each of the plurality of the sub-pixel element electrodes having a different surface area, and all of the sub-pixel element electrodes of one of the pixel element electrodes receiving an equal voltage according to an image signal in a moving picture display mode and receiving respective bit signals of a digital image signal in a still picture display mode; and a common electrode disposed on the second substrate, the common electrode facing the pixel element electrodes, wherein the display device is configured to perform a refreshing operation for refreshing the voltages retained by the retaining circuits with a first cycle, and an inverting operation for inverting the voltages retained by the retaining circuits, so that a direction of an electric field applied to the liquid crystal is inverted, with a second cycle, the inverting operation coinciding with one of the refreshing operations. - View Dependent Claims (8, 9, 10, 11)
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12. An active matrix display device comprising:
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a first substrate and a second substrate; a liquid crystal disposed between the first substrate and the second substrate; a plurality of pixel element electrodes disposed on the first substrate; a plurality of sub-pixel element electrodes disposed for each of the pixel element electrodes and having different surface areas, each of the sub-pixel element electrodes of one of the pixel element electrodes receiving an equal voltage according to an image signal in a moving picture display mode and receiving a respective bit signal of a digital image signal in a still picture display mode; a plurality of retaining circuits disposed on the first substrate, each of the retaining circuits corresponding to one of the sub-pixel element electrodes and comprising a capacitance element retaining a voltage; and a common electrode disposed on the second substrate, the common electrode facing the pixel element electrodes, wherein each of the sub-pixel element electrodes corresponding to one of the pixel element electrodes possesses an equal capacitance, the capacitance being a sum of a capacitance of the corresponding capacitance element and a liquid crystal capacitance formed between the corresponding sub-pixel element electrode and the common electrode through the liquid crystal. - View Dependent Claims (13, 14)
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15. An active matrix display device comprising:
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a first substrate and a second substrate; a liquid crystal disposed between the first substrate and the second substrate; a plurality of pixel element electrodes disposed on the first substrate; a plurality of sub-pixel element electrodes disposed for each of the pixel element electrodes and having different surface areas, each of the sub-pixel element electrodes of one of the pixel element electrodes receiving an equal voltage according to an image signal in a moving picture display mode and receiving a respective bit signal of a digital image signal in a still picture display mode; a plurality of retaining circuits disposed on the first substrate, each of the retaining circuits corresponding to one of the sub-pixel element electrodes and comprising a capacitance element retaining a voltage; and a common electrode disposed on the second substrate, the common electrode facing the pixel element electrodes, wherein a smaller sub-pixel element electrode among the sub-pixel element electrodes of one of the pixel element electrodes corresponds to a retaining circuit with larger capacitance among the retaining circuits of said one of the pixel element electrodes. - View Dependent Claims (16, 17)
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18. An active matrix display device comprising:
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a first substrate and a second substrate; a liquid crystal disposed between the first substrate and the second substrate; a plurality of pixel element electrodes disposed on the first substrate; a plurality of sub-pixel element electrodes disposed for each of the pixel element electrodes and having different surface areas, each of the sub-pixel element electrodes of one of the pixel element electrodes receiving an equal voltage according to an image signal in a moving picture display mode and receiving a respective bit signal of a digital image signal in a still picture display mode; a plurality of retaining circuits disposed on the first substrate, each of the retaining circuits corresponding to one of the sub-pixel element electrodes and comprising a capacitance element retaining a voltage; and a common electrode disposed on the second substrate, the common electrode facing the pixel element electrodes, wherein a capacitance of one of the capacitance elements is larger than a liquid crystal capacitance formed between the common electrode and the corresponding sub-pixel element electrode through the liquid crystal. - View Dependent Claims (19, 20)
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21. An active matrix display device comprising:
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a first substrate and a second substrate; a liquid crystal disposed between the first substrate and the second substrate; a plurality of pixel element electrodes disposed on the first substrate; a plurality of sub-pixel element electrodes disposed for each of the pixel element electrodes and having different surface areas, each of the sub-pixel element electrodes of one of the pixel element electrodes receiving an equal voltage according to an image signal in a moving picture display mode and receiving a respective bit signal of a digital image signal in a still picture display mode; a plurality of pixel element selection transistors, each of the pixel element selection transistors corresponding to one of the sub-pixel element electrodes and selecting the corresponding sub-pixel element electrode; a plurality of retaining circuits disposed on the first substrate, each of the retaining circuits corresponding to one of the sub-pixel element electrodes and comprising a capacitance element retaining a voltage; and a common electrode disposed on the second substrate, the common electrode facing the pixel element electrodes, wherein the surface area of one of the sub-pixel element electrodes determines a capacitance of the corresponding capacitance element and a channel width of the corresponding pixel element selection transistor. - View Dependent Claims (22)
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23. An active matrix display device comprising:
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a pixel element; a pixel element electrode disposed for the pixel element; a plurality of sub-pixel element electrodes disposed for the pixel element electrode, each of the sub-pixel element electrodes having a different surface area, receiving an equal voltage according to an image signal in a moving picture display mode and receiving a respective bit signal of a digital image signal in a still picture display mode; and a plurality of retaining circuits disposed for the pixel element electrode, each of the retaining circuits corresponding to one of the sub-pixel element electrodes, retaining a voltage, and supplying the voltage to the corresponding sub-pixel element electrode.
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Specification