OLED Pixel Circuit Sensing With Static Protection for Uniform Brightness
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Solution Overview
Problem
Existing semiconductor substrates face issues with brightness uniformity due to differences in threshold voltage and mobility of drive transistors, leading to deviations in pixel brightness and potential damage from static electricity generated by sensing circuits.
Innovation Solution
A semiconductor substrate design incorporating a driving circuit, data writing circuit, storage circuit, sensing circuit, and protecting circuit, with transistors configured to control and protect the light-emitting element, and a method to detect and compensate for brightness deviations while preventing static electricity from damaging the OLED device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensing circuit is added to detect pixel brightness, then measurement precision is improved, but static electricity is generated that may damage the light emitting element
Solution Approach 1:
The patent introduces a protecting circuit as an intermediary component between the sensing circuit and the light emitting element. This protecting circuit includes a controlling transistor that is turned off during sensing operations, thereby blocking the path of static electricity generated by the sensing circuit from reaching and damaging the light emitting element, while still allowing the sensing circuit to perform its measurement function.
2Device complexity
If transistors with different threshold voltages and mobility are used, then device complexity is reduced, but brightness uniformity deteriorates
Solution Approach 1:
The patent implements a sensing circuit that measures the actual brightness of the light emitting element and feeds this information back to the driving circuit. The driving circuit then compensates for brightness deviations caused by transistor parameter variations by adjusting the drive current, thereby maintaining brightness uniformity across pixels despite using transistors with different threshold voltages and mobility.
3Reliability
If the protecting circuit is always on to prevent static electricity, then reliability is improved, but power consumption increases due to continuous current supply
Solution Approach 1:
The patent makes the protecting circuit dynamic by controlling the switching state of its transistor based on operational phases. During normal display operations, the protecting circuit transistor is turned on to provide protection and current supply. During sensing operations, the transistor is turned off to prevent static electricity while minimizing power consumption, thus adapting the circuit's behavior to different operational requirements.
Data Source
AI summary
A semiconductor substrate, a driving method therefor, and a semiconductor display apparatus are provided. Each pixel unit includes a pixel circuit and a light emitting element. The pixel circuit includes a driving circuit, a data writing circuit, a storage circuit, a sensing circuit, and a protecting circuit. The driving circuit controls a drive current that drives the light emitting element. The data writing circuit writes a data signal into the driving circuit. The storage circuit stores the data signal. The sensing circuit is configured to connect the driving circuit with a sensing signal line. The protecting circuit is configured to prevent static electricity generated by the sensing circuit from flowing to the light emitting element and supply the drive current jointly with the driving circuit. The light emitting element is configured to emit light according to the drive current.