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AssigneeHitachi Displays, Ltd.
InventorsHiroki Awakura, Yasuyuki Kudo, Norio Mamba
Estimating the term…
A display device includes a display panel having pixels arranged in a matrix form, a driving circuit for outputting an analog voltage according to a video signal to the pixels through signal lines, a plurality of measuring circuits each for detecting the amount of transmitted light, a single totalizing circuit for totalizing the results of measurements made by the measuring circuits, and a control circuit for adjusting a potential on a common electrode of the display panel in accordance with the result of the totalization from the totalizing circuit. The results of measurements made by the plurality of measuring circuits are totalized by the single totalizing circuit.
A display device comprising:
A method of adjusting a voltage applied to a common electrode of a display device, said method comprising the steps of:
Dependencies are inferred from the claim text.
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Using an active matrix: details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors
Circuit arrangements or driving methods for the control of single liquid crystal cells: circuits comprising a photodetector
Control of matrices with row and column drivers: control of polarity reversal in general
Improving the quality of display appearance: compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g.…
About 2 years 4 months of term left · ends 9 Mar 2029 (estimated)
The present application claims priority from Japanese patent application serial No. 2005-271798 filed on Sep. 20, 2005, the content of which is hereby incorporated by reference into this application.
The present invention relates to a display device for displaying an image on a display panel illuminated by a back light source, and more particularly, to a display device which can adjust a voltage applied to a common electrode.
In a liquid crystal element used for a display device, a continuously applied DC voltage results in a degradation in image quality similar to burn-in. For this reason, in a liquid crystal display, a liquid crystal element is applied with signal voltages which include a positive voltage (Vsig+) and a negative voltage (Vsig−) alternately applied in each frame period. Also, when a voltage (VCOM) is applied to a common electrode of the liquid crystal element, the display luminance is determined in accordance with (Vsig+)−(VCOM) when the positive voltage is applied and with (VCOM)−(Vsig−) when the negative voltage is applied.
FIG. 1 is a block diagram illustrating the configuration of a display device which has a function of automatically adjusting a voltage applied to a common electrode according to the present invention;
FIG. 2 is a schematic diagram of a dummy pixel 21;
FIG. 3 is a schematic diagram of the dummy pixel 21 in a reverse mount;
A first embodiment will be described.
FIG. 1 is a schematic diagram illustrating an exemplary configuration of a display device having a function of automatically adjusting a common electrode voltage according to the present invention. The display device comprises a TFT array substrate 1; a precharge capacitance (Cp) 2; an analog buffer amplifier 3; a precharge voltage source (Vprc) 4; a precharge switch 5; a sample/hold circuit 6 for use when a positive signal is applied; a sample/hold circuit 7 for use when a negative signal is applied; a comparator 8 which outputs a comparison result 9; a controller 10; a sampling signal 11 for use when the positive signal is applied; a sampling signal 12 for use when the negative signal is applied; a common electrode power supply 13; a display area 14; dummy pixels 21; photodiodes 31; a liquid crystal element (Clcd) 32; TFT elements 33; a signal line driving circuit 51; a vertical scanning circuit 52; a first signal line 61; a second signal line 62; a first scanning line 71; a second scanning line 72; a third scanning line 73; and a fourth scanning line 74.
The TFT array substrate 1 is one of glass substrates of a liquid crystal panel, generally made up of two glass substrates, on which TFT elements are formed. The present invention may be applied to a direct-view type liquid crystal display device or to a projection type liquid crystal display device.