OLED Pixel Circuit with Shared Compensation and Touch Units
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Solution Overview
Problem
Traditional OLED display pixel circuits face challenges in achieving uniform image display due to inconsistent threshold voltages of driving transistors, which affect current flow and hinder fine pixel resolution, especially when integrating touch functions like capacitive and photosensitive touch, leading to increased pixel pitch and higher costs.
Innovation Solution
A pixel circuit design that includes a drive unit, compensation unit, and light-emitting unit, where adjacent pixel structures share a compensation unit and touch units, allowing for shared data lines and read lines to adjust drive voltages and generate touch signals, thereby reducing the impact of threshold voltages and integrating touch functions efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transmittance compensation circuit is added to compensate for liquid crystal transmittance variations, then display quality is improved, but pixel circuit complexity and area increase
Solution Approach 1:
The compensation circuit is merged with the existing pixel circuit by sharing the emission control line EL between the drive transistor and compensation transistor. This integration allows transmittance compensation functionality to be added without requiring completely separate circuit components, thereby improving display quality while limiting the increase in circuit complexity.
Solution Approach 2:
The emission control line EL serves multiple functions: it controls both the drive transistor for normal pixel operation and the compensation transistor for transmittance compensation. This multi-functionality reduces the need for additional dedicated control lines and simplifies the overall circuit structure despite adding compensation capability.
2Illumination intensity
If compensation transistors are added to each pixel, then transmittance compensation is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The compensation transistor is configured to turn on before the drive transistor during the emission period, allowing the compensation capacitor to be charged to the compensation voltage Vc in advance. This preliminary action ensures that when the drive transistor turns on, the compensation voltage is already established, reducing the impact of threshold voltage variations and relaxing manufacturing precision requirements.
Solution Approach 2:
The compensation method changes the voltage parameter Vc stored in the compensation capacitor based on the actual transmittance characteristics. By adjusting this voltage parameter dynamically rather than relying on fixed physical parameters, the system can compensate for manufacturing variations without requiring extremely precise fabrication.
3Device complexity
If the emission control line EL is shared between drive and compensation transistors, then circuit complexity is reduced, but control timing becomes more difficult
Solution Approach 1:
The compensation transistor is designed to operate in a preliminary phase before the drive transistor during the emission period. This temporal sequencing allows both transistors to share the emission control line EL without conflict, as the compensation transistor completes its charging function before the drive transistor begins its pixel driving function, simplifying the control line structure while maintaining manageable timing requirements.
Data Source
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AI summary
The present invention provides a pixel circuit comprising a plurality of pixel structures, each pixel structure comprising a drive unit, a compensation unit and a light-emitting unit, wherein in the adjace nt first pixel structure and second pixel structure, the first pixel structure further comprises a capacitive touch unit, and the second pixel structure further comprises a photosensitive touch unit; the compensation unit in the first pixel structure, the compensation unit in the second pixel structure, the capacitive touch unit and the photosensitive touch unit share a data line, and the capacitive touch unit and the photosensitive touch unit share a read line.