Display Device Gamma Voltage Adjustment for Luminance Uniformity
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Solution Overview
Problem
In organic light emitting display devices, variations in pixel driving voltage due to position and image patterns cause uneven luminance across the display panel, leading to inconsistent image reproduction.
Innovation Solution
A display device with a data driving circuit, gate driving circuit, power supply unit, and gamma reference voltage adjusting unit that measures pixel driving voltage in real time and adjusts the gamma compensation voltage range to ensure consistent luminance across the panel, using a sensing line and sensing switch transistor to synchronize with scan signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common pixel driving voltage is supplied to all pixels through a power line, then the device structure is simple, but the voltage drop varies by position causing luminance inconsistency
Solution Approach 1:
The patent applies local quality by adjusting the gamma reference voltage according to the position of pixels on the display panel. Different regions (top, bottom, left, right) receive different gamma reference voltage values to compensate for position-dependent voltage drops. This ensures that pixels at different locations achieve consistent luminance despite the common power supply structure.
2Ease of operation
If the pixel driving voltage is maintained at a constant level, then the power supply control is simple, but the voltage drop varies with image pattern causing luminance inconsistency
Solution Approach 1:
The patent implements feedback by measuring the actual pixel driving voltage at different positions and using these measurements to adjust the gamma reference voltage. The gamma reference voltage adjusting unit receives voltage measurement values and dynamically adjusts the gamma reference voltage range to compensate for voltage drops that occur under different image patterns (dark screen vs. bright screen).
Solution Approach 2:
The patent changes the gamma reference voltage parameter based on measured pixel driving voltage values. The gamma reference voltage adjusting unit modifies the gamma reference voltage range according to the actual voltage conditions, allowing the system to adapt to varying voltage drops caused by different image patterns while maintaining simple power supply control.
3Manufacturing precision
If real-time voltage measurement is implemented at multiple positions, then luminance consistency is achieved, but the device complexity increases
Solution Approach 1:
The patent applies universality by using the same sensing line and sensing switch transistor structure across multiple positions on the display panel. The sensing line is extended to different regions (top, bottom, left, right) but uses the same basic measurement mechanism, reducing overall system complexity while achieving comprehensive voltage monitoring.
Solution Approach 2:
The patent introduces a sensing line as an intermediary element that connects the power line to the measurement system. The sensing line, controlled by sensing switch transistors, allows voltage measurement at multiple positions without requiring direct access to each pixel's power supply node, thereby simplifying the measurement system architecture.
Data Source
AI summary
A display device is proposed, the display device including a display panel having a plurality of pixels; a data driving circuit converting pixel data to a data voltage based on a gamma compensation voltage to supply the same to the plurality of pixels through a plurality of data lines; a gate driving circuit supplying a scan signal through a gate line connected to pixels of each horizontal line of the display panel; a power supply unit supplying a pixel driving voltage to the plurality of pixels through a power line; and a gamma reference voltage adjusting unit adjusting a range of the gamma compensation voltage based on a pixel driving voltage measurement value measured in synchronization with the scan signal at a plurality of positions on the display panel.