Reference Voltage Switch Matrix for Reliable LCD Gamma Correction
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Solution Overview
Problem
Existing reference voltage selection circuits for LCD panels face challenges in achieving accurate gamma correction, particularly with increased resolution and diversification of LCD panels, as they tend to increase circuit scale and reliability issues.
Innovation Solution
A reference voltage selection circuit that employs a switch matrix configuration with first to fourth switch elements, where the first switch element outputs a selection voltage as a reference voltage based on gamma correction data, and subsequent switch elements output the same selection voltage as different reference voltages, with a bypass circuit and transistor configurations to enhance reliability and reduce current density, thereby simplifying the circuit configuration and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If switch elements are configured to selectively output reference voltages based on gamma correction data, then gamma correction accuracy is improved, but the risk of switch element destruction increases due to high current density
Solution Approach 1:
The patent applies different current density characteristics to different switch elements based on their position in the circuit. Specifically, the first switch element (connected to ground power supply voltage) is designed with lower current density in its channel region compared to other switch elements. This localized differentiation in electrical characteristics allows the circuit to maintain high gamma correction accuracy while protecting the ground-referenced switch element from destruction due to excessive current density.
2Measurement precision
If the number of reference voltages is increased to achieve accurate gamma correction, then gamma correction accuracy is improved, but circuit complexity increases
Solution Approach 1:
The patent segments the reference voltage selection function across multiple switch elements arranged in a structured configuration. Each switch element is responsible for selecting specific reference voltages based on gamma correction data bits. This segmentation allows the circuit to handle multiple reference voltage levels (improving gamma correction accuracy) while maintaining organized, manageable circuit complexity through systematic division of selection functions.
Solution Approach 2:
The patent implements dynamic voltage selection where switch elements are selectively enabled or disabled based on the state of gamma correction data bits. This dynamic operation allows the circuit to adaptively select from multiple reference voltages (improving gamma correction accuracy) without requiring all switch elements to be permanently active, thereby managing circuit complexity through conditional activation rather than static full-configuration deployment.
Data Source
AI summary
A reference voltage selection circuit includes a first switch element SW1 that outputs a first selection voltage among first to third selection voltages as a first reference voltage among first and second reference voltages, a second switch element SW2 that outputs the second selection voltage as the first reference voltage, a third switch element SW3 that outputs the second selection voltage as the second reference voltage, and a fourth switch element SW4 that outputs the third selection voltage as the second reference voltage. The first to fourth switch elements SW1 to SW4 are ON/OFF-controlled using gamma correction data that contains at least three bits. When the first selection voltage is a ground power supply voltage, reliability can be improved by protecting the first switch element.