Display device and driving method thereof
AssigneeHitachi, Ltd.
InventorsYoshiro Mikami, Yoshiharu Nagae, Toshihiro Sato, Yoshiyuki Kaneko, Shosaku Tanaka
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Abstract
In an active matrix display device utilizing electro-optical elements such as organic EL elements capable of obtaining a high image quality with a low power, each pixel circuit is provided with: a sampling circuit for sampling a signal voltage on a signal wiring line synchronously with a scan pulse; a reference voltage; and a comparator circuit. In the pixel circuit, the sampled signal voltage is compared with the reference voltage and the display time of each EL device is controlled by the period until the relation between the signal voltage and reference voltage is inverted, to thereby control the light emission time in one frame period.
Claims21
A display device including a pixel surrounded by wiring lines, said pixel being applied with a reference voltage supplied from a reference voltage line which is one of said wiring lines, wherein:
- said pixel is provided with a sampling circuit, a voltage converter circuit, a voltage comparator circuit and an organic EL driver circuit;
- said sampling circuit fetches a signal voltage on a signal line which is one of said wiring lines as a sampled voltage controlled by a voltage on a scan line which is one of said wiring lines;
- said voltage converter circuit converts the sampled voltage into a voltage waveform varying with time;
- said voltage comparator circuit compares the voltage waveform converted from the sampled voltage with the reference voltage to generate a control voltage output changing when a sign of subtraction between the compared voltages is inverted;
- and
- said organic EL driver circuit controls turn-on/turn-off of an organic EL element in said pixel in accordance with the control voltage output.
A display device including a pixel surrounded by wiring lines crossing each other, said pixel being applied with a reference voltage supplied from a reference voltage line which is one of said wiring lines, wherein:
- said pixel is provided with a sampling circuit, a voltage comparator circuit, and an organic EL driver circuit;
- said sampling circuit fetches a signal voltage on a signal line which is one of said wiring lines as a sampled voltage controlled by a voltage on a scan line which is one of said wiring lines, the sampled voltage being processed to vary with time and provided in said pixel;
- said voltage comparator circuit compares the sampled voltage with the reference voltage to generates a control voltage output changing when a sign of subtraction between the compared voltages is inverted;
- and
- said organic EL driver circuit controls turn-on/turn-off of an organic EL element in said pixel in accordance with the control voltage output.
A display device including a pixel surrounded by wiring lines crossing each other, said pixel being applied with a reference voltage supplied on a reference voltage line from said wiring lines, wherein:
- said pixel is provided with a sampling circuit, a voltage comparator circuit, and an organic EL driver circuit;
- said sampling circuit fetches a signal voltage on a signal line from said wiring lines as a sampled voltage controlled by a voltage on a scan line from said wiring lines, and said sampling circuit includes a sampled voltage processing circuit for changing the sampled voltage toward a reference voltage on the reference voltage line from said wiring lines with time;
- said voltage comparator circuit compares the reference voltage on the reference voltage line with the sampled voltage to generate a control voltage output changing with an inversion of a sign of subtraction between the reference voltage and the sampled voltage;
- and
- said organic EL driver circuit controls switching of an organic EL element in said pixel in accordance with the control voltage output.
A display device including a pixel surrounded by wiring lines crossing each other, said pixel being applied with a reference voltage supplied on a reference voltage line from said wiring lines, wherein:
- said pixel is provided with a signal voltage sampling circuit, a reference voltage sampling circuit, a voltage comparator circuit, and an organic EL driver circuit;
- said signal voltage sampling circuit fetches a signal voltage on a signal line from said wiring lines as a sampled signal voltage controlled by a voltage on a scan line from said wiring lines, the sampled signal voltage being processed to vary with time and provided in said pixel;
- said reference voltage sampling circuit samples the reference voltage on the reference voltage line as a sampled reference voltage which is converted into a pixel reference voltage;
- said voltage comparator circuit compares the pixel reference voltage with the sampled reference voltage to generate a control voltage output changing when a sign of subtraction between the compared voltages is inverted;
- and
- said organic EL driver circuit controls turn-on/turn-off of an organic EL element in said pixel in accordance with the control voltage output.
A display device including a pixel surrounded by wiring lines crossing each other, said pixel being applied with a reference voltage supplied on a reference voltage line from said wiring lines, wherein:
- said pixel is provided with a signal voltgage sampling circuit, a reference voltage sampling circuit, a voltage comparator circuit, and an organic EL driver circuit;
- said signal voltage sampling circuit fetches a signal voltage on a signal line from said wiring lines as a sampled signal voltage controlled by a voltage on a scan line from said wiring lines;
- said reference voltage sampling circuit samples the reference voltage on the reference voltage line as a sampled reference voltage which is converted into a pixel reference voltage;
- said voltage comparator circuit compares the sampled reference voltage with the pixel reference voltage to generate a control voltage output changing when a sign of subtraction between the sampled reference voltage and the pixel reference voltage is inverted;
- and
- said organic EL driver circuit controls switching of an organic EL element in said pixel in accordance with the control voltage output.
Dependencies are inferred from the claim text.