Shared-Circuit Shift Register for Uniform OLED Brightness
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Solution Overview
Problem
The non-uniformity of threshold voltages in driving transistors of organic light emitting diode (OLED) pixels leads to uneven brightness, and existing shift registers are complex, hindering the development of narrow-bezel display devices.
Innovation Solution
A simplified shift register design with shared output and pull-down control circuits, allowing for superposition of signals and alternating operation of input and reset circuits, which reduces the circuit complexity and enables narrow bezel displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a compensation circuit is added to correct threshold voltage non-uniformity, then brightness uniformity is improved, but device complexity increases
Solution Approach 1:
The patent combines the compensation circuit and shift register into a single integrated structure. The compensation circuit shares transistors (Q1, Q2, Q3, Q4) and capacitors (C1, C2) with the shift register functionality, eliminating the need for separate compensation circuits in each pixel. This merging approach provides threshold voltage compensation while maintaining simple circuit structure.
Solution Approach 2:
The transistors and capacitors in the proposed circuit serve multiple functions. For example, transistor Q1 acts as both a compensation transistor and a switching element in the shift register. The capacitor C1 serves both as a compensation capacitor and a storage element. This multi-functionality reduces the total number of components while achieving both compensation and shift register operations.
2Ease of manufacture
If the shift register structure is simplified to enable narrow-bezel displays, then ease of manufacture is improved, but functionality may be compromised
Solution Approach 1:
The patent merges the compensation circuit and shift register into a single integrated structure. The compensation circuit shares transistors (Q1, Q2, Q3, Q4) and capacitors (C1, C2) with the shift register functionality, eliminating the need for separate compensation circuits in each pixel. This merging approach provides threshold voltage compensation while maintaining simple circuit structure.
Solution Approach 2:
The transistors and capacitors in the proposed circuit serve multiple functions. For example, transistor Q1 acts as both a compensation transistor and a switching element in the shift register. The capacitor C1 serves both as a compensation capacitor and a storage element. This multi-functionality reduces the total number of components while achieving both compensation and shift register operations.
Data Source
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AI summary
Provided is shift register including signal input circuits, reset circuits and control and output circuit. Operation cycle of shift register is divided into phases non-overlapping in time, each phase includes at least first and second sub-phases. Signal input circuits are each configured to apply signal provided by respective signal input terminal to pull-up control terminal in first sub-phase of respective phase in response to signal of respective input control terminal. The reset circuits are each configured to apply first power supply signal provided by first power supply terminal to the pull-up control terminal in second sub-phase of respective phase in response to signal of respective reset control terminal. The input circuits and the reset circuits share the control and output circuit outputting a signal based on signal of the pull-up control terminal, the waveform of the signal being superposition of waveforms corresponding to signals provided by the signal input circuits.