Pixel Circuit Compensation for Display Contrast and Leakage
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Solution Overview
Problem
Display apparatuses using electroluminescent diodes face issues with achieving sufficient darkness in gray scale representation, leading to reduced contrast due to data voltage exceeding the output range of driver integrated circuits.
Innovation Solution
A pixel circuit design incorporating a data writing transistor, compensation circuit, and light emitting control circuit, where the compensation circuit compensates for the voltage of the drive transistor, and the light emitting control circuit controls the light emitting device to emit light, using low temperature poly-silicon and metal oxide semiconductor materials to enhance stability and reduce leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If data voltage is increased to display gray scale, then the display range is improved, but the dark state is not sufficiently dark resulting in reduced contrast
Solution Approach 1:
The patent introduces a compensation circuit as an intermediary component between the data writing transistor and the drive transistor. This compensation circuit includes a compensation capacitor connected in parallel with the threshold voltage generation circuitry, which mediates the voltage fluctuations and stabilizes the gate voltage of the drive transistor, thereby maintaining proper dark state while enabling extended gray scale display range.
Solution Approach 2:
The patent changes the electrical parameters of the pixel circuit by introducing additional capacitive elements and modifying the voltage generation circuitry. The compensation capacitor alters the voltage-time characteristics and impedance levels, enabling the circuit to handle higher data voltages while maintaining stable operation and proper contrast ratios.
2Adaptability or versatility
If driver IC output range is extended to accommodate higher data voltage, then the display gray scale range is improved, but the device complexity increases
Solution Approach 1:
The patent segments the voltage generation and compensation functions into separate circuit modules within the pixel circuit. The data writing transistor handles data voltage input, while the compensation circuit independently manages voltage stabilization. This segmentation allows the driver IC to operate within its original output range while the pixel circuit internally compensates for voltage variations, avoiding the need to redesign the entire driver IC.
Solution Approach 2:
The compensation circuit acts as an intermediary between the data writing transistor and the drive transistor, absorbing the complexity of voltage range extension. By placing the compensation functionality at the pixel circuit level rather than the driver IC level, the patent extends the data voltage range without proportionally increasing driver IC complexity.
3Ease of manufacture
If conventional transistor materials are used, then the manufacturing process is simpler, but leakage current is higher reducing display uniformity
Solution Approach 1:
The patent employs composite material strategies by combining low temperature poly-silicon (LTPS) materials with conventional semiconductor structures. The LTPS active layer in the data writing transistor is integrated with conventional driver transistor structures, creating a hybrid device that benefits from both the low leakage characteristics of LTPS and the manufacturing simplicity of conventional processes. The compensation circuit also utilizes material composition optimization to reduce leakage while maintaining manufacturability.
Data Source
AI summary
The present disclosure provides a pixel circuit, a display panel and a display apparatus. A gate of a data writing transistor is electrically connected with a first scan line, a first electrode of the data writing transistor is electrically connected with a data line, and a second electrode of the data writing transistor is electrically connected with a first electrode of a drive transistor; a compensation circuit is electrically connected with the gate of the drive transistor; and a light emitting control circuit is electrically connected with a first power signal line, the first electrode and the second electrode of the drive transistor, and a first electrode of a light emitting device, respectively; an orthographic projection of the compensation circuit on a base substrate partially overlaps with an orthographic projection of the first power signal line on the base substrate.