Overdrive Unit Placement for Display Signal Processing
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Solution Overview
Problem
Existing image display devices face issues with moving image characteristics, power consumption, contrast, and the occurrence of fake contours or blurs when using both frame frequency conversion and overdrive methods, as the overdrive processing overloads the device and affects the emphasis of image signals.
Innovation Solution
An image display device is designed with an overdrive unit placed subsequent to an area control unit, featuring a liquid crystal panel, a segmented backlight, a delay unit, an interpolation image signal generator, a frame frequency converter, a gain calculator, and a multiplier to optimize image signal processing and backlight control, ensuring proper emphasis and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frame frequency conversion and overdrive are combined to improve moving image characteristics, then moving image quality is improved, but the overdrive processing overloads the image display device and increases memory access speed requirements
Solution Approach 1:
The patent applies preliminary action by performing overdrive processing on the input image signal before frame frequency conversion. The overdrive unit processes the original frame-rate signal (e.g., 60Hz) to generate overdriven image signals, which are then subjected to frame frequency conversion to generate high frame-rate display signals (e.g., 120Hz). This reverses the conventional order and reduces processing load during high frame-rate operation.
2Use of energy by stationary object
If area control is applied subsequent to frame frequency conversion to improve power consumption and contrast, then power efficiency and contrast are improved, but the emphasis by overdrive is weakened causing excessive or deficient emphasis
Solution Approach 1:
The patent performs overdrive processing as a preliminary action before area control and frame frequency conversion. The overdrive unit processes the input image signal to emphasize motion information, and then subsequent processing stages (frame frequency conversion and area control) operate on this pre-emphasized signal. This ensures that the overdrive emphasis is preserved and not weakened by later processing stages.
Solution Approach 2:
The patent applies area control with different gain values to different regions of the display. The area control unit divides the display into multiple regions and applies region-specific gain adjustment to the overdriven image signals. This local quality approach allows optimized power consumption and contrast for each region while preserving the overall overdrive effect through the use of region-independent gain calculation based on maximum gradation values.
3Reliability
If overdrive processing is performed after frame frequency conversion, then moving image characteristics are improved, but the speed of accessing memory increases which overloads the device
Solution Approach 1:
The patent performs overdrive processing as a preliminary action on the input image signal at the original frame rate before frame frequency conversion. This avoids the need to perform overdrive processing on high frame-rate signals, thereby reducing memory access speed requirements and preventing device overload while still achieving improved moving image characteristics in the final high frame-rate display output.
Data Source
AI summary
An image display device includes a gain calculator, a multiplier and an overdrive unit. The gain calculator calculates a ratio “Gmax0/Gmax1” as gain, with respect to each segmented region of liquid crystal panel. The symbol “Gmax1” represents a maximum gradation in one frame period of an image signal to be supplied to each segmented region. The symbol “Gmax0” represents a maximum gradation to be determined depending on the number of bits in the image signal. The multiplier multiplies an image signal subjected to frame frequency conversion in a frame frequency conversion unit by the gain to generate an image signal subjected to the area control processing, with respect to each segmented region. The overdrive unit emphasizes the image signal subjected to the area control processing, using an image signal generated by delaying the image signal subjected to the area control processing for one frame period.