Projector Synchronization Timing Adjustment for Flicker and Brightness
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Solution Overview
Problem
Projectors that synchronize the drive frequency of the light source lamp and the liquid crystal light valve for extended operation periods suffer from brightness ununiformity and flicker issues.
Innovation Solution
The synchronization timing of the current drive signal and the vertical synchronizing signal for the light source and liquid crystal light valve is dynamically adjusted based on accumulated operating time, using a timing control part to shift the selection timing of the scan line and the intensity fluctuation of the light source, thereby reducing brightness ununiformity and flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive frequency of the light source lamp and the drive frequency of the liquid crystal light valve are synchronized for extended operation, then flicker is suppressed, but brightness ununiformity occurs in specific positions of the projected image
Solution Approach 1:
The patent applies the dynamics principle by making the synchronization timing adjustable rather than fixed. The synchronization timing between the light source drive signal and liquid crystal light valve drive signal can be dynamically changed to different timing based on accumulated operating time. This dynamic adjustment prevents brightness ununiformity that occurs with fixed synchronization timing during extended operation, while still maintaining flicker suppression benefits.
Solution Approach 2:
The patent applies parameter changes by modifying the synchronization timing parameter. The timing relationship between the light source drive signal and the vertical synchronizing signal of the liquid crystal light valve is changed from a fixed state to a variable state that can be adjusted based on operating conditions. This parameter change resolves the contradiction by allowing the system to adapt to extended operation conditions while maintaining flicker suppression.
2Illumination intensity
If the synchronization timing is changed frequently, then brightness ununiformity is reduced, but flicker may occur due to timing changes
Solution Approach 1:
The patent applies periodic action by changing the synchronization timing at predetermined intervals based on accumulated operating time rather than continuously or frequently. This periodic adjustment approach allows the system to maintain stable operation for extended periods without frequent timing changes that could cause flicker, while still preventing brightness ununiformity by periodically resetting the timing relationship.
Data Source
AI summary
A projector includes an alternately-current-driven light source and a liquid crystal light valve that modulates light output from the light source. The light source and the liquid crystal light valve are driven under a condition that a current drive signal of the light source and a vertical synchronizing signal of the liquid crystal light valve are synchronized, and a synchronization timing of the current drive signal and the vertical synchronizing signal is changed to a different synchronization timing based on accumulated operating time at intervals of each time or a plural times of activation or with the same synchronization timing.