Reflective Display Pixel Circuit Voltage Segmentation
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Solution Overview
Problem
Reflective displays with high visibility and low power consumption face issues with oxide film degradation and leakage current when high driving voltages are applied, which degrades thin film transistors (TFTs).
Innovation Solution
The solution involves a pixel array with a data driver and a scan driver that transmit target voltages to pixels in specific voltage level ranges, using switching transistors and storage capacitors to manage voltage levels and reduce voltage differences across TFTs, thereby minimizing degradation and leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high driving voltage is applied to obtain high reflexibility, then display visibility is improved, but oxide films of TFTs are degraded and leakage current is generated
Solution Approach 1:
The voltage transmission process is divided into two distinct time periods: a first time period for transmitting target voltage when voltage levels are between first and second voltage levels, and a second time period for transmitting target voltage when voltage levels are between second and third voltage levels. This temporal segmentation allows different voltage transmission strategies to be applied at different times, preventing continuous high voltage stress on TFT oxide films while maintaining display visibility.
Solution Approach 2:
The pixel circuit dynamically switches between different voltage transmission modes based on the target voltage level. The switching transistor and buffer transistor are controlled to transmit voltage only during appropriate time periods, creating a dynamic voltage management system that adapts to different display requirements while protecting TFT components from degradation.
2Power
If high driving voltage is applied to obtain high reflexibility, then display performance is improved, but leakage current is generated in TFTs
Solution Approach 1:
The pixel circuit is configured to receive and store the target voltage in advance during the first time period before it is actually needed for display. The storage capacitor holds the voltage, allowing the high voltage to be applied briefly and then removed, preventing continuous voltage stress that would generate leakage current while still achieving the required display performance.
Solution Approach 2:
The voltage transmission operates in periodic cycles with distinct phases: a first time period for voltage transmission when appropriate, and a second time period when voltage transmission is avoided. This periodic operation pattern allows the display to achieve high reflexibility during active periods while preventing leakage current during inactive periods.
Data Source
AI summary
A reflective display device includes a pixel array including a plurality of pixels; a data driver connected to each of the plurality of pixels and configured to transmit a target voltage to each of the plurality of pixels; and a scan driver connected to each of the plurality of pixels and configured to transmit a switching signal for determining whether the data driver transmits the target voltage to some of the plurality of pixels, wherein each of the plurality of pixels is configured to receive the target voltage for single data information, receive the target voltage in a first time period when the target voltage transmitted to each of the plurality of pixels is between a first voltage level and a second voltage level, and receive the target voltage in a second time period when the target voltage is between the second voltage level and a third voltage level.