Flat Panel Display Driving Circuit Double-Pulse Scan Signal
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Solution Overview
Problem
Conventional active pixel driving circuits for flat panel displays face challenges in fully charging pixels quickly enough as resolution increases, requiring additional pre-charge circuits and control signals, which complicate the architecture and increase the number of thin film transistors needed.
Innovation Solution
A driving circuit with a horizontal scan shift register that includes a bidirectional circuit capable of generating a double-pulse scan signal, where the first pulse enables pre-charge and the second pulse allows for actual pixel voltage input, eliminating the need for an additional pre-charge circuit block and using only three additional thin film transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If an additional pre-charge circuit is utilized to pre-charge a pixel, then pixel charging time is reduced, but the architecture becomes more complicated and more thin film transistors are required
Solution Approach 1:
The patent merges the pre-charge function with the existing horizontal scan shift register by utilizing the bidirectional circuit to generate a double-pulse scan signal. The first pulse serves as the pre-charge signal and the second pulse as the actual pixel voltage input signal, eliminating the need for separate pre-charge circuitry while maintaining both functions within the existing architecture.
Solution Approach 2:
The bidirectional circuit in the horizontal scan shift register is made multi-functional by configuring it to generate a double-pulse scan signal. This single circuit component now performs both the pre-charge function (first pulse) and the pixel voltage input function (second pulse), replacing what would traditionally require separate dedicated pre-charge circuits.
2Loss of time
If an additional pre-charge circuit is utilized to pre-charge a pixel, then pixel charging time is reduced, but the number of thin film transistors increases
Solution Approach 1:
The patent merges the pre-charge function with the existing horizontal scan shift register by utilizing the bidirectional circuit to generate a double-pulse scan signal. The first pulse serves as the pre-charge signal and the second pulse as the actual pixel voltage input signal, eliminating the need for separate pre-charge circuitry while maintaining both functions within the existing architecture.
3Device complexity
If a conventional shift register is used without pre-charge capability, then the architecture remains simple, but pixel charging is incomplete as resolution increases
Solution Approach 1:
The patent implements preliminary action by generating a double-pulse scan signal where the first pulse pre-charges the pixel before the second pulse delivers the actual pixel voltage. This preliminary pre-charge action ensures that the pixel is ready to receive the full voltage signal, guaranteeing complete charging even as display resolution increases and charging time decreases.
Data Source
AI summary
A driving circuit. The driving circuit includes a plurality of scan shift register cells, a pair of complementary clock signal lines, and a horizontal start signal generator. Each scan shift register cell comprises a bidirectional circuit, a shift register coupled to the bidirectional circuit, a transmission gate coupled to the shift register, and a data line coupled to the transmission gate. The complementary clock signal lines are coupled to the shift registers. The horizontal start signal generator provides a horizontal start signal to the bidirectional circuits in the first and a subsequent scan shift register cells. The shift register in each scan shift register cell provides an output signal to the bidirectional circuit in the next scan shift register cell. The bidirectional circuit in each scan shift register cell also receives the output signal from the shift register in the next scan shift register cell.