Source Driver Charge-Share Circuit for Power-Off Flicker Control
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Solution Overview
Problem
The increase in pixel capacitance due to larger TFT liquid crystal display panels results in slow removal of electric charge when power is off, leading to screen flickering.
Innovation Solution
A source driver with a charge share line and power off detection circuit that short-circuits source lines to a common voltage line and ground line, allowing quick removal of common voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the display panel size is increased, then the display area is improved, but the pixel capacitance increases causing slow charge removal and screen flickering
Solution Approach 1:
The patent applies preliminary action by preparing discharge paths (charge share lines and switches) in advance before power-off occurs. When power is turned off, the detection circuit immediately activates pre-configured discharge paths to rapidly remove accumulated charge from source lines, preventing screen flickering without waiting for natural charge dissipation.
Solution Approach 2:
The patent introduces charge share lines and detection circuits as intermediary elements between the source lines and ground. These intermediaries provide dedicated charge removal pathways that bypass the slow natural discharge process, enabling rapid charge evacuation from the increased pixel capacitance in larger display panels.
2Ease of manufacture
If the common voltage is removed sequentially through the printed circuit board, then the basic power-off procedure is followed, but the falling speed of the common voltage is not sufficiently short causing display artifacts
Solution Approach 1:
The patent segments the charge removal function by separating it from the main power-off sequence. Instead of relying on the single slow path through the printed circuit board, the source driver is divided into multiple independent output amplifiers, each with its own charge share line and detection circuit, enabling parallel and rapid charge removal from multiple source lines simultaneously.
Solution Approach 2:
The patent implements dynamic charge removal by using detection circuits that monitor voltage levels in real-time and activate discharge paths only when needed. The charge share switches dynamically connect source lines to ground based on detected voltage thresholds, creating an adaptive power-off sequence that optimizes charge removal speed while maintaining ease of manufacture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Quickly suppresses screen flickering by efficiently discharging accumulated charge when power is turned off, improving display quality without increasing costs.
Implementation Method 1
a charge share line, having a charge share switch provided to be able to connect output lines outputting the pixel drive voltages of the plurality of output amplifiers
Implementation Method 2
efficiently discharging accumulated charge when power is turned off
Data Source
AI summary
A source driver includes: output amplifiers, supplying pixel drive voltages to source lines of a display device based on a video signal; a charge share line, having a charge share switch able to connect output lines outputting the pixel drive voltages; a common voltage line, connected to a common voltage electrode of the display device; a first power supply line, supplying a first voltage; a switch part, able to connect the charge share line and the common voltage line with the first power supply line; and a control part, including a power off detection circuit that detects stoppage of supply of the first voltage. When it is detected that the first power supply line is off, the control part short-circuits the source lines by the charge share line and connects the charge share line and the common voltage line with the first power supply line by the switch part.