Multi-gray scale driving circuit for cholesteric liquid crystal panel, driving method, and display device
A cholesteric liquid crystal and drive circuit technology, applied in static indicators, nonlinear optics, instruments, etc., can solve the problems of unsmoothed load current in the power supply unit and low conversion efficiency of the booster circuit, etc.
Inactive Publication Date: 2012-11-28
FUJITSU LTD
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Problems solved by technology
On the other hand, since the charging and discharging cycle of a cholesteric liquid crystal panel displaying a still image is long, which is about milliseconds, there is a problem that the load current of the power supply unit is hardly smoothed, and the booster circuit only Low conversion efficiency can be obtained
Method used
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[0067] Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0068] First, refer to Image 6 The principle of the driving method of the cholesteric liquid crystal panel of the embodiment will be described. In this driving method, the circuit upper limit value of the booster circuit of the power supply unit is limited to a predetermined value calculated from the charge and discharge cycle in a plurality of charges and discharges with different cycles. like Image 6 As shown, the average current when the cycle is 3.5 ms is very small (for example, about 1 / 7) compared with the average current when the cycle is 0.5 ms. The ratio of the current upper limit value when the period is 3.5ms to the current upper limit value when the period is 0.5ms is equal to the ratio of the average current when the period is 3.5ms to the average circuit when the period is 0.5ms. Thereby, irrespective of the charge and discharge cycle, the transient c...
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Disclosed is a multi-gray scale driving circuit for a cholesteric liquid crystal panel which can effectively suppress a variation in load current (a ratio of a peak current to an average current) even in the case where a charging / discharging period is largely changed. This circuit is a multi-gray scale driving circuit for driving the cholesteric liquid crystal display panel using a plurality of driving phases different in driving period. The multi-gray scale driving circuit comprises a current upper limit control circuit which calculates the upper limit of the supply current of a liquid crystal driving power source and outputs an upper limit control signal and a supply current restriction circuit which restricts the supply current of the liquid crystal driving power source to be equal to or less than an upper limit value indicated by the upper limit control signal. The current upper limit control circuit switches the upper limit control signal according to the driving period of each driving phase.
Description
technical field [0001] The present invention relates to a cholesteric liquid crystal (cholesteric LCD) display device, its multi-grayscale driving circuit and driving method, and particularly relates to reducing the multi-grayscale performance of a cholesteric liquid crystal panel with multiple driving phases (drive phases) with different driving cycles. Power consumption technology when driving. Background technique [0002] Electronic paper using cholesteric liquid crystals is attracting attention as the only electronic paper capable of "bright color display, full color (full color) display, and powerless display". Cholesteric liquid crystals are sometimes also called chiral nematic liquid crystals (chiral nematic LCD), which are added to nematic liquid crystals by adding a relatively large amount (tens of percent) of chiral additives (chiral (chiral) materials) to the nematic liquid crystals. Molecules of nematic liquid crystals form helical cholesteric liquid crystals. ...
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IPC IPC(8): G02F1/133G09G3/20G09G3/36
CPCG09G2300/0486G02F2203/30G09G2330/025G02F1/13718G09G3/3651
Inventor 新海知久
Owner FUJITSU LTD