Liquid Crystal Display Dummy Scan Circuit for Stripe Uniformity
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Solution Overview
Problem
The block inversion driving method for liquid crystal display devices experiences unevenness in display quality due to varying loads on the scanning signal line drive circuit during different scanning periods, leading to horizontal stripe unevenness.
Innovation Solution
The introduction of a dummy scanning period after polarity reversal in the block inversion driving method, where scanning signal lines are grouped and sequentially scanned with identical polarity signal electric potentials, and at least one scanning signal line is subjected to a dummy scan during the dummy scanning period to equalize loads on the scanning signal line drive circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If block inversion driving is used to reduce power consumption and improve charging rate, then power consumption is suppressed and charging rate is improved, but display unevenness in the form of horizontal stripes occurs
Solution Approach 1:
A dummy scanning period is inserted immediately after polarity reversal to preliminarily activate scanning signal lines before actual data scanning. This preliminary action equalizes the load conditions for all scanning lines, preventing the display unevenness that would otherwise occur due to varying load states when scanning lines are activated at different times after polarity reversal.
Solution Approach 2:
The dummy scanning period acts as an intermediary mechanism between polarity reversal and actual data scanning. It mediates the load distribution across scanning signal lines by ensuring all lines are activated under identical load conditions before real data is written, thereby eliminating horizontal stripe artifacts while maintaining the power consumption benefits of block inversion driving.
2Productivity
If scanning signal lines are activated at different times after polarity reversal, then scanning efficiency is improved, but load variation causes electric potential supplied to pixels to vary
Solution Approach 1:
The dummy scanning period serves as a preliminary activation phase where all scanning signal lines are brought to the same load state before actual data scanning begins. This ensures that when different scanning lines are activated at different times, they all start from an equalized load condition, preventing variations in electric potential supplied to pixels.
3Manufacturing precision
If dummy scanning period is inserted after polarity reversal, then display uniformity is improved, but scanning time is increased
Solution Approach 1:
The dummy scanning period implements a partial scanning action that is sufficient to equalize load conditions but not so extensive as to significantly impact overall scanning time. By activating scanning lines for a brief dummy period just long enough to equalize loads, the solution achieves display uniformity while minimizing the time penalty.
Data Source
AI summary
At least one embodiment of a liquid crystal display device including a display unit having scan signal lines divided into a plurality of groups which are successively selected. While the scan signal lines belonging to the selected group are successively scanned horizontally, signal potentials of the same polarity are successively supplied to a data signal line. The polarity of the signal potential is reversed between a preceding group and a subsequent group which are selected continuously. A plurality of dummy scan periods are inserted between the horizontal scan period corresponding to the last horizontal scan in the preceding group and the horizontal scan period corresponding to the first horizontal scan in the subsequent group. In each of the dummy scan periods, one of the scan signal lines which belong to the group selected after the preceding group is subjected to a dummy scan so that the scan signal line is maintained in an active state for a predetermined period and then deactivated so as to align the load state of a scan signal line drive circuit. This can reduce irregularities of the horizontal stripes when the data signal line is subjected to the block reverse drive.