Gamma Voltage Generator Offset Compensation for Display Yield
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Solution Overview
Problem
Display devices manufactured using the same process can have variations in luminance and color coordinate characteristics, leading to some devices not meeting target quality levels, resulting in excessive tact time for multi-time programming (MTP) operations and potential discarding of defective products.
Innovation Solution
A gamma voltage generator that includes a gamma reference voltage storage block, an additional offset storage block, an additional offset setting block, and a gamma reference voltage calculation block, which selectively adds additional offset values to gamma reference voltage values based on gamma select information to generate final gamma reference voltages, allowing defective products to be upgraded to fair quality products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MTP operation is performed only at reference luminance level to reduce tact time, then productivity is improved, but manufacturing precision deteriorates at other luminance levels
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing additional offset values in an additional offset storage block before the MTP operation. These offset values are prepared in advance to compensate for luminance level variations, allowing the system to quickly adjust gamma reference voltages for different luminance levels without performing time-consuming MTP operations at each level. This resolves the contradiction by maintaining high productivity while ensuring manufacturing precision across all luminance levels.
Solution Approach 2:
The patent changes the parameter of gamma reference voltage by adding pre-calculated offset values to the base gamma reference voltage. This parameter adjustment allows the system to compensate for manufacturing variations at different luminance levels without reperforming the entire MTP operation. The gamma reference voltage calculation block dynamically adjusts the voltage parameters based on stored offset values, thereby maintaining image quality precision while preserving fast MTP operation speed.
2Manufacturing precision
If additional offset values are applied to defective display devices, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the additional offset storage functionality into the existing gamma voltage generator structure. The additional offset storage block is integrated with the gamma reference voltage storage block and the calculation block, forming a unified system. This merging approach allows the application of additional offset values to improve manufacturing precision while minimizing the increase in device complexity by reusing existing structural components rather than adding entirely separate systems.
3Manufacturing precision
If MTP operation is performed at multiple luminance levels to ensure image quality, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The patent performs preliminary calculations and stores additional offset values for multiple luminance levels before the actual MTP operation. This preliminary preparation eliminates the need to perform time-consuming MTP operations at each luminance level during production. The stored offset values are readily available for quick application, thereby maintaining manufacturing precision across multiple luminance levels while preserving high productivity during the MTP operation.
Solution Approach 2:
The patent applies partial action by performing MTP operation only at the reference luminance level rather than at all luminance levels. The additional offset values for other luminance levels are calculated and stored in advance. This partial MTP operation approach reduces the overall operation time significantly while still ensuring image quality precision through the pre-prepared offset compensation mechanism.
Data Source
AI summary
A gamma voltage generator included in a display device includes a gamma reference voltage storage block configured to store gamma reference voltage values at reference gray levels, an additional offset storage block configured to store additional offset values for the gamma reference voltage values at the reference gray levels, an additional offset setting block configured to store gamma select information representing whether the additional offset values are to be applied or not, a gamma reference voltage calculation block configured to generate final gamma reference voltage values by selectively adding the additional offset values to the gamma reference voltage values depending on the gamma select information, and a gamma reference voltage generation block configured to generate gamma reference voltages corresponding to the final gamma reference voltage values.