Over-driving Device for LCD Response Time
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Solution Overview
Problem
Liquid crystal display panels face a long response time due to slow rotational speed of liquid crystal molecules, which prevents the brightness of pixels from reaching the desired level within a frame, especially in large-sized displays.
Innovation Solution
An over-driving device comprising a compression circuit, buffer, comparison circuit, and over-driving unit that compares and processes image signals across frames to determine when to over-drive the display, utilizing a decompression circuit to generate enable signals for adjusting gray values and brightness, potentially with a delay circuit to synchronize signal timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the rotational speed of liquid crystal molecules is increased to shorten response time, then the brightness change speed is improved, but the stability of liquid crystal molecule orientation may deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing over-drive voltage values in a lookup table during system initialization or idle periods. When a gray level change is detected, the system immediately queries the pre-computed table for the appropriate over-drive voltage, eliminating the need for real-time complex calculations and thus shortening response time without affecting molecule orientation stability.
Solution Approach 2:
The patent changes the voltage parameter by applying an over-drive voltage that is higher than the normal drive voltage for a predetermined period after the liquid crystal molecules have completed their reorientation. This parameter change accelerates the brightness response without requiring continuous high voltage that would destabilize molecule orientation, as the over-drive is applied only temporarily after the molecules have already rotated to their target position.
2Loss of time
If over-driving method is applied to shorten response time, then the brightness change duration is reduced, but the complexity of signal processing increases
Solution Approach 1:
The patent performs preliminary action by pre-computing and storing over-drive voltage values in a lookup table during system initialization or idle periods. When a gray level change is detected, the system immediately queries the pre-computed table for the appropriate over-drive voltage, eliminating the need for real-time complex calculations and thus shortening response time without significantly increasing processing complexity.
Solution Approach 2:
The patent uses a lookup table that copies and stores pre-computed over-drive voltage values for different gray level transitions. Instead of calculating the optimal over-drive voltage in real-time, the system copies the appropriate pre-computed value from the table, significantly simplifying the signal processing complexity while maintaining the response time benefit.
3Speed
If over-drive voltage is applied to accelerate brightness change, then the response time is shortened, but the energy consumption increases
Solution Approach 1:
The patent applies periodic action by implementing a timing control mechanism that applies over-drive voltage only for a predetermined period after the liquid crystal molecules have completed their reorientation. The over-drive voltage is not applied continuously but rather in a controlled time window, which accelerates the brightness change during the critical period while limiting total energy consumption compared to continuous over-drive application.
Solution Approach 2:
The patent changes the voltage parameter dynamically by applying over-drive voltage only when and where needed. The system determines the appropriate over-drive voltage magnitude and duration based on the specific gray level transition and molecular reorientation state, optimizing the balance between response time improvement and energy consumption by avoiding unnecessary voltage application.
Data Source
AI summary
An over-driving device is provided. In a first frame, a compression circuit compresses a first image signal to generate a first compression image signal, and a buffer temporarily stores the first compression image signal. In a following second frame, the compression circuit compresses a second image signal to generate a second compression image signal, and the buffer outputs the first compression image signal to serve as a first buffer image signal. A comparison circuit compares the second compression image signal and the first buffer image signal and generates an enable signal according comparison result. A decompression circuit decompresses the first buffer image signal to generate a previous image signal. An over-driving unit receives the second image signal to serve to a current image signal and receives the previous image signal and the enable signal. The over-driving unit over drives the display device or not according to the enable signal.