LCD Luminance Correction via Vertical Blank Detection
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Solution Overview
Problem
Liquid crystal display devices experience luminance deviations due to variations in the vertical blank period, leading to screen tearing, stuttering, and flickering issues, which affect display quality.
Innovation Solution
A liquid crystal display device with a luminance correction value calculator circuit that adjusts light source driving signals based on the vertical blank period, using reference counting values to correct luminance levels for each light-emitting block, and determines the display mode as adaptive or normal synchronous to maintain consistent image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive synchronization technique is used to match image frame rate by adjusting vertical blank interval, then screen tearing and stuttering are eliminated, but average luminance changes for each frame causing flickering
Solution Approach 1:
The patent changes the luminance parameter of the light source based on the vertical blank interval duration. By detecting the actual vertical blank interval and adjusting the light source luminance accordingly, the system compensates for luminance variations caused by adaptive synchronization, thereby eliminating flickering while maintaining screen tearing elimination
Solution Approach 2:
The patent implements a feedback mechanism where the system detects the actual vertical blank interval duration and uses this information to adjust the light source driving signals. This closed-loop control ensures that luminance remains stable even when the vertical blank interval varies to match different image frame rates
2Reliability
If vertical synchronization mode is used to eliminate screen tearing, then screen tearing is reduced, but picture delay occurs causing screen stuttering
Solution Approach 1:
The patent makes the light source driving signals dynamic by adjusting them according to the actual vertical blank interval duration. This dynamic adjustment allows the system to adapt to varying frame rates without fixed picture delay, thereby reducing screen stuttering while maintaining screen tearing elimination
Data Source
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AI summary
A liquid crystal display device includes a liquid crystal display panel, a light source configured to provide the liquid crystal display panel with a light, a vertical blank detector circuit configured to calculate a counting value of a vertical blank period of a frame by counting a synchronization signal, a luminance correction value calculator circuit configured to calculate a luminance correction value by comparing the counting value of the vertical blank period with a plurality of reference counting values, and a light source driver configured to generate a light source driving signal and provide the light source driving signal to the light source. The light source driving signal has a normal level corresponding to a normal luminance value in an active period of the frame and has a correction level corresponding to the luminance correction value in the vertical blank period of the frame.