Display Driving Device Gamma Voltage Adjustment for Waterfall Defect
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Solution Overview
Problem
The existing backlight systems in display devices, which use Pulse Width Modulation (PWM) to control brightness, often result in a 'waterfall defect' due to differences in resistance-capacitance delay when the backlight transitions between bright and dark states, affecting the display panel's image quality.
Innovation Solution
A display driving device and method that includes a PWM signal generating circuit, a PWM signal acquisition circuit, a gamma voltage debugging circuit, and a gamma voltage switching circuit to dynamically adjust gamma voltage reference data based on PWM signal levels, ensuring equal pixel voltage values in both bright and dark states, thereby eliminating the RC delay difference and preventing the waterfall defect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If PWM signal is used to control backlight brightness, then brightness control is achieved, but waterfall defect occurs due to RC delay difference between bright and dark states
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the gamma voltage based on the PWM signal state. When the PWM signal is at high level (backlight bright), one set of gamma voltage parameters is used; when at low level (backlight dark), another set of gamma voltage parameters is used. This parameter adjustment compensates for the RC delay difference between bright and dark states, eliminating the waterfall defect while maintaining brightness control functionality.
Solution Approach 2:
The patent implements dynamics by making the gamma voltage adaptive and changeable according to the backlight state. The gamma voltage debugging circuit dynamically selects different gamma voltage reference data based on whether the PWM signal is at high or low level, allowing the system to adapt to varying backlight conditions and eliminate the static RC delay issue that causes waterfall defect.
2Manufacturing precision
If gamma voltage is adjusted to eliminate waterfall defect, then image quality is improved, but device complexity increases due to additional circuits
Solution Approach 1:
The patent merges the gamma voltage debugging function with the existing backlight PWM control system. The gamma voltage debugging circuit is integrated into the display driving device, sharing the same control architecture and signal pathways where possible. This merging approach allows the system to eliminate waterfall defect through gamma voltage adjustment while minimizing the increase in device complexity by reusing existing circuit resources.
Solution Approach 2:
The patent introduces a gamma voltage debugging circuit as an intermediary component between the PWM signal generating circuit and the display panel. This intermediary circuit receives the PWM signal, determines its state (high or low level), and accordingly selects appropriate gamma voltage reference data to compensate for RC delay differences. By positioning this debugging circuit as an intermediary, the patent achieves image quality improvement while keeping the overall system architecture relatively simple and modular.
Data Source
AI summary
A display driving device, a display driving method, a display module and a display device are provided. The display driving device includes: a PWM signal generating circuit configured to generate a PWM signal; a PWM signal acquisition circuit, configured to identify whether the PWM signal output by the PWM signal generating circuit is at a high level or a low level; a gamma voltage debugging circuit, configured to debug a gamma voltage to obtain a first group of gamma voltage reference data corresponding to the PWM signal at the high level and a second group of gamma voltage reference data corresponding to the PWM signal at the low level in each gray-scale image; and a gamma voltage switching circuit.