Electrooptical Device Precharge Thinning Drive Noise Control
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Solution Overview
Problem
Existing electrooptical devices face challenges in efficiently performing precharge thinning drive without causing noise and simplifying control, especially with increased scanning lines and data lines, leading to potential rotation noise and complex control requirements.
Innovation Solution
An electrooptical device with a scanning line drive unit, data line drive unit, data line selection unit, and control unit that alternately selects and distributes precharge voltage to data lines in a manner that disperses the voltage distribution across pixels, allowing for shortened horizontal scanning periods without changing the duty of signal selection, thus simplifying control and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If precharge thinning drive is performed every predetermined horizontal scanning period, then the horizontal scanning period can be shortened, but rotation noise appears in display and control becomes complicated
Solution Approach 1:
The patent applies periodic action by alternating the precharge signal supply pattern between different horizontal scanning periods. In odd horizontal scanning periods, precharge signals are supplied to all data lines, while in even horizontal scanning periods, precharge signals are supplied to only half of the data lines. This periodic alternation prevents the accumulation of phase differences that cause rotation noise while still achieving the benefit of shortened horizontal scanning periods.
2Loss of time
If precharge thinning drive is performed every predetermined horizontal scanning period, then the horizontal scanning period can be shortened, but control becomes complicated
Solution Approach 1:
The control complexity is reduced by using a periodic alternation pattern between odd and even horizontal scanning periods. The control unit simply needs to track whether the current period is odd or even and adjust the precharge signal supply accordingly, rather than implementing complex control logic for arbitrary predetermined periods. This periodic approach maintains simplicity while achieving the time-saving benefit.
3Reliability
If precharge signal is supplied to all data lines, then writing support is improved, but the horizontal scanning period becomes longer
Solution Approach 1:
The patent applies segmentation by dividing the data lines into two groups and supplying precharge signals to only one group at a time during even horizontal scanning periods. This segmentation allows the precharge operation to be completed more quickly for half the data lines, thereby shortening the horizontal scanning period while still providing adequate writing support through the alternating pattern.
Solution Approach 2:
By periodically alternating between supplying precharge signals to all data lines (odd periods) and half the data lines (even periods), the system achieves an average reduction in horizontal scanning period length while maintaining overall writing support quality. The periodic nature ensures that all data lines receive precharge signals regularly, just with reduced frequency during even periods.
Data Source
AI summary
Precharge thinning drive is performed without causing rotation noise and without requiring complicated control. A signal generation circuit that supplies an image signal with a magnitude in accordance with a tone to be displayed to pixels via data lines in a tone display period and supplies a precharge voltage to the data lines in a precharge period before the tone display period in one horizontal scanning period, a signal distribution circuit that is provided between the signal generation circuit and the data lines and selects the data lines, and a control circuit that controls the signal distribution circuit such that a predetermined number of data lines are alternately not selected in the precharge period are provided, and the control circuit controls the signal distribution circuit such that non-selection of the data line is different every predetermined horizontal scanning period.