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Liquid crystal display and its light source driving method

A technology of liquid crystal display device and light source driving, which can be used in static indicators, instruments, etc., and can solve the problems of narrow space, malfunction of inverter, and inability to light up.

Inactive Publication Date: 2007-06-13
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the extremely narrow duty of this whisker-like pulse (the time ratio is below 1%), it is not only impossible to perform lighting corresponding to the duty, but may even induce misoperation of the inverter

Method used

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  • Liquid crystal display and its light source driving method
  • Liquid crystal display and its light source driving method
  • Liquid crystal display and its light source driving method

Examples

Experimental program
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Effect test

no. 1 Embodiment

[0082] First, a liquid crystal display device according to a first embodiment of the present invention will be described. FIG. 1 is a block diagram showing the structure of a liquid crystal display device according to a first embodiment of the present invention. The liquid crystal display device shown in FIG. 1 includes a liquid crystal module 1 , a video processing unit 2 , a PWM dimming driving circuit unit 3 and a backlight unit 4 .

[0083] The video processing unit 2 includes a video signal processing circuit 21 , a system control circuit 22 and a delay circuit (delay circuit) 23 . The video signal processing circuit 21 converts an input video signal such as a video signal of a television signal into a signal suitable for processing in the liquid crystal module 1 . Specifically, the video signal processing circuit 21 outputs video signals VR, VG, VB divided into three primary colors (RGB), vertical synchronous signal Vsyn, horizontal synchronous signal Hsyn, and pixel cl...

no. 2 Embodiment

[0104] Next, a liquid crystal display device according to a second embodiment of the present invention will be described. 5 is a block diagram showing the structure of a liquid crystal display device according to a second embodiment of the present invention. The difference between the liquid crystal display device shown in FIG. 5 and the liquid crystal display device shown in FIG. 1 is that the backlight unit 4 is changed to a backlight unit 4a, and three 1 / 4 vertical period delay circuits 5a-5c are added, and the other parts Since it is the same as the liquid crystal display device shown in FIG. 1 , the same parts are given the same symbols and their descriptions are omitted, and the different parts will be described in detail below.

[0105] The 1 / 4 vertical period delay circuit 5a receives the inverter drive signal Vout1 from the PWM dimming drive circuit section 3, and outputs the inverter drive signal Vout2 delayed by 1 / 4 of the vertical period from the inverter drive sig...

no. 3 Embodiment

[0122] Next, a liquid crystal display device according to a third embodiment of the present invention will be described. Fig. 13 is a block diagram showing the structure of a liquid crystal display device according to a third embodiment of the present invention. The difference between the liquid crystal display device shown in FIG. 13 and the liquid crystal display device shown in FIG. 1 is that the system control circuit 22 is changed to a system control circuit 22a that also outputs whisker pulse (whisker pluse) limiting duty data PD, and The PWM generation unit 32 for black insertion dimming is changed to a PWM generation unit 32a for black insertion dimming that also includes a pulse width limiting circuit 39, and the others are the same as those of the liquid crystal display device shown in FIG. 1 , so the same parts are marked The same symbols are used and their explanations are omitted, and the different parts will be described in detail below.

[0123] The system cont...

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Abstract

A PWM generating section (32) for black insertion lighting control outputs a black insertion PWM pulse VBL for driving a fluorescent lamp (43) such that a black insertion period for unlighting the fluorescent lamp (43) and a period for lighting the fluorescent lamp (43) are provided in one vertical period, a PWM generating section (31) for luminance lighting control outputs a lighting control PWM pulse Vpwm1 for PWM driving the fluorescent lamp (43) so as to repeat lighting and unlighting in the lighting period, an AND circuit (33) outputs an inverter drive signal Vout1 where the lighting control PWM pulse Vpwm1 and the black insertion PWM pulse VBL are superposed, and an inverter (42) drives the fluorescent lamp (43) by applying a voltage corresponding to the inverter drive signal Vout1 to the fluorescent lamp (43).

Description

technical field [0001] The present invention relates to a liquid crystal display device provided with a light source provided on the back of a liquid crystal panel and a method for driving the light source thereof, in particular to a method for changing the lighting period ( A liquid crystal display device that performs dimming according to the time ratio (time ratio) between the lights-on period and the lights-out period. Background technique [0002] A liquid crystal display device includes a liquid crystal panel and a backlight unit having a light source provided on the back of the liquid crystal panel. In each pixel of the liquid crystal panel, the liquid crystal is driven according to a video signal, light emitted from the backlight is transmitted, and an image is displayed on the liquid crystal panel. [0003] Generally, fluorescent tubes (fluorescent lamps) are often used as light sources in the backlight. Fluorescent tube, the hollow glass tube is filled with disch...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G09G3/36G02F1/133G09G3/20G09G3/34
Inventor 熊本泰浩
Owner PANASONIC CORP
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