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Driving voltage output circuit

A driving voltage and output circuit technology, which is applied in the field of driving voltage output circuit, can solve problems such as display unevenness, fluctuation, and image quality degradation, and achieve the effect of reducing circuit scale and improving precision

Inactive Publication Date: 2008-04-23
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] However, in the above-mentioned drive voltage output circuit, since the positive drive voltage and the negative drive voltage are applied by mutually different output amplifiers, the difference (amplitude) between the positive and negative drive voltages due to the offset (offset) of the output amplifiers ) will change
Therefore, when used in a liquid crystal display device or the like, display unevenness occurs and image quality deteriorates.

Method used

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  • Driving voltage output circuit

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Experimental program
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Effect test

Embodiment approach 1

[0026] FIG. 1 is a block diagram showing a configuration of a driving voltage output circuit that applies a driving voltage to, for example, a predetermined number of source lines of a liquid crystal panel. In this drive voltage output circuit, there are: D / A converters 101·102 that output positive or negative image signal voltages according to the image data of each pixel; Amplifier 103; Gain, for example, amplifier 104·105 of 1; Output selector 106 selectively switching the output of amplifier 104·105; Distribution circuit 107 sequentially connecting the output of 106 to each source line; And, to the above-mentioned amplifier 104·105 supply the power supply circuit 110 with the power supply voltage of 2 power supplies.

[0027] The input selector 103 has switches 103a to 103f for switching the image signal voltage from the D / A converter 101·102 to the amplifier 104·105 or to the amplifier 105·104. Also, when the polarity of the image signal voltage input to the amplifier 10...

Embodiment approach 2

[0077] As the amplifiers 104 and 105, various amplifiers that operate with two power supplies, such as operational amplifiers, can be used. However, as described above, as long as they are in the operating state of selectively outputting positive and negative driving voltages, they are selectively switched. The state of the current source (current source) and the state of the current sink (current sink) can also easily simplify the structure and reduce the scale of the circuit.

[0078] Specifically, the amplifier 104 includes, for example, as shown in FIG. 5 , a differential unit 201 , an active load unit 202 , and an output unit 203 similar to those of a normal operational amplifier. The output unit 203 has a P-channel transistor 203a, switches 203b and 203c, constant current sources 203d and 203e, switches 203f and 203g, and an N-channel transistor 203h. The output unit 204 of the amplifier 105 has the same structure as the output unit 203 of the above-mentioned amplifier 1...

Embodiment approach 3

[0082] In addition, the amplifiers 104·105 may be configured as shown in FIG. 7 . In the example of the figure, compared with the above-mentioned output unit 203·204, the output unit 205·206 is provided with a transistor 205i· which forcibly turns on / off the transistor 203a·203h by controlling the gate potential of the transistor 203a·203h. 205j, instead of switches 203b·203g. In such a configuration, although the switching speed tends to be slower than that of Embodiment 2, the influence of the on-resistance of the switches 203b and 203g can be avoided.

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Abstract

A driving voltage output circuit is provided for selectively outputting a positive driving voltage and a negative driving voltage. The driving voltage includes: an amplifier which amplifies and outputs, as a driving voltage, a selectively input positive or negative input signal; and a power supply voltage switching circuit which switches a power supply voltage to be supplied to the amplifier according to a polarity of the input signal. In the above circuit, both the positive and negative driving voltages are output from the single amplifier, so that the difference (amplitude) between the positive and negative driving voltages is free from offset influence even if the offset of the amplifier varies. Further, the range of the actual operation voltage is reduced to approximately one half of the amplitude. This means that the elements composing the circuit can have a breakdown voltage that is one half of that of the conventional one, thereby leading to reduction in area of the elements occupying the semiconductor substrate and an increase in operation speed of the circuit. The present invention has its object of increasing the accuracy of output driving voltages and reduce the circuit scale of the driving voltage output circuit.

Description

technical field [0001] The present invention relates to a driving voltage output circuit for driving a source line of a liquid crystal display device or an electroluminescent display device. Background technique [0002] A source line of a liquid crystal display device or an electroluminescent display device is generally driven by alternately applying positive and negative driving voltages. As a drive voltage output circuit that outputs such a drive voltage, there is known a circuit-scale circuit that outputs a drive voltage by selectively switching between an output amplifier for positive drive voltage output and an output amplifier for negative drive voltage. Lowered technology. [0003] Patent Document 1: Japanese Unexamined Patent Publication No. 9-26765 [0004] However, in the above-mentioned drive voltage output circuit, since the positive drive voltage and the negative drive voltage are applied by mutually different output amplifiers, the difference (amplitude) bet...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G09G3/20G09G3/36G09G3/18G02F1/133
CPCG09G2310/027G09G3/20G09G2310/0254H03F3/45G09G3/36G09G3/30
Inventor 小岛友和三宅健二大森哲郎
Owner PANASONIC CORP