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Pulsewidth regulating device for adjusting liquid crystal display brightness contrast

A technology of pulse width modulation and liquid crystal display, which is applied in the direction of static indicators, instruments, color TV parts, etc., and can solve the problem of inability to make fine adjustments, the complexity of voltage adjustment circuits, large power consumption, and difficulty in fine adjustments And other issues

Inactive Publication Date: 2004-10-06
ELAN MICROELECTRONICS CORPORATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] 1. Excessive power consumption - due to the existence of a DC path in the voltage adjustment circuit, and due to the power supply, it is impossible to design the DC resistance too small, so the power consumption is very considerable, about 10μA series of power consumption, very Not good for standby use
[0006] 2. Circuit difficulty and circuit area are too large
[0007] 3. Unable to make fine adjustments - it is difficult to make fine adjustments due to the complexity of the voltage adjustment circuit

Method used

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  • Pulsewidth regulating device for adjusting liquid crystal display brightness contrast
  • Pulsewidth regulating device for adjusting liquid crystal display brightness contrast
  • Pulsewidth regulating device for adjusting liquid crystal display brightness contrast

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Embodiment Construction

[0042] Generally speaking, the waveform output by the LCD driver is as follows figure 1 As shown, it is divided into two categories - static type and scanning type (or multiplexing type). The static output is a relatively simple single-point control, and its Vrms value is as follows:

[0043] Vrms - on = 1 / 2 Vop Vrms-off=0 (Vop is the maximum output voltage)

[0044] The scanning Vrms value is related to the number of bias voltages and the number of cycles. The scanning method is that the commonpin (com) outputs a scanning waveform, and performs time-sharing scanning on the segment (seg) output signal. As for the voltage sensed by the LCD panel (panel), it is actually the voltage difference of seg-com, so as long as the voltage difference of seg-com can be made large enough within the common scan time, the LCD panel can be reversed immediately, resulting in Light ...

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Abstract

The on-off period of the scanning waveform for the liquid crystal display is utilized to adjust the contrast of brightness. The circuit includes the counter, the comparator, the T trigger, the multiple inverter and the multiple 'and' gates. The compact circuit occupies a small area and uses small power consumption since it is composed of the digital circuits.

Description

technical field [0001] The present invention relates to a liquid crystal display (LCD), and in particular to an adjustment circuit for adjusting the brightness contrast (Constrast) of the liquid crystal display by means of pulse width modulation, which utilizes a digital control circuit to adjust the on-off of LCD scanning On-Off duty, to achieve bright contrast adjustment, has the advantages of low power consumption, small area and high adjustment rate. Background technique [0002] In the current electrical system, there are many LCD liquid crystal displays as the interface between man and machine, and due to the needs of use, there is a trend of more and more LCD points. However, the LCD has characteristics related to viewing angle and high voltage, so that the brightness of the LCD cannot be kept constant for users. Therefore, it becomes an important issue for all LCD drivers to adjust the brightness contrast of LCD by the user. [0003] In orde...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G02F1/133G09G3/36H04N5/57
Inventor 王开怀
Owner ELAN MICROELECTRONICS CORPORATION