Pixel Circuit Threshold Compensation Beyond 1H Data Timing
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Solution Overview
Problem
Existing display apparatuses face challenges in compensating for electrical characteristic deviations between pixels due to process variations, with compensation time typically restricted to 1H (horizontal period), leading to potential errors and reduced image quality.
Innovation Solution
A pixel circuit design that includes a compensation capacitor and separate compensation and data program periods, using a voltage unrelated to the data voltage to diode-connect the driving transistor, allowing for extended threshold voltage compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If compensation is performed using data voltage through data line within 1H time, then compensation can be completed within horizontal period, but compensation time is insufficient leading to compensation errors
Solution Approach 1:
The patent divides the pixel circuit operation into separate compensation period and data program period. The compensation period is dedicated solely to threshold voltage compensation using a compensation capacitor, while the data program period handles data voltage sampling. This temporal segmentation allows sufficient compensation time without restricting compensation to the limited 1H data line window, thereby improving compensation accuracy while maintaining adequate time allocation.
Solution Approach 2:
The patent performs threshold voltage compensation in advance during a dedicated compensation period before the data program period. By using a compensation capacitor to store the threshold voltage information beforehand, the circuit ensures that compensation is completed with sufficient time, eliminating the rush to complete compensation within the constrained 1H data line availability and reducing compensation errors.
2Device complexity
If compensation and data program are performed simultaneously within 1H time, then circuit operation is simplified, but compensation errors increase due to insufficient compensation time
Solution Approach 1:
The patent separates compensation and data program operations into distinct time periods. The compensation period handles threshold voltage compensation using the compensation capacitor, while the data program period handles data voltage sampling. This temporal segmentation improves compensation accuracy by providing dedicated time for each function, while the overall circuit structure remains relatively simple through systematic phase separation.
3Adaptability or versatility
If data line is used for compensation, then data voltage can be utilized for compensation, but compensation is restricted to 1H time causing compensation errors
Solution Approach 1:
The patent creates a dedicated compensation period separate from data program period. During the compensation period, the compensation capacitor is used to store threshold voltage information, independent of data line timing constraints. This segmentation allows the circuit to maintain voltage utilization flexibility while achieving accurate compensation by decoupling compensation operations from the restricted 1H data line window.
Solution Approach 2:
The patent introduces a compensation capacitor as an intermediary element to store threshold voltage information. This compensation capacitor acts as a mediator between the driving transistor and the data holding circuitry, allowing compensation to be performed with sufficient time using a voltage unrelated to data voltage, thereby improving compensation accuracy while maintaining overall circuit versatility.
Data Source
AI summary
A display apparatus comprises a display panel including pixels. A pixel circuit of each pixel includes: a driving transistor having a first electrode corresponding to a first node, a gate electrode corresponding to a second node, and a second electrode corresponding to a third node; a light-emitting element having connected to the first node and a low-potential voltage; a storage capacitor connected to the second and first nodes; a compensation capacitor having one electrode connected to a fifth node and another electrode connected to a first voltage; a first transistor connected to the second and fifth nodes; a second transistor connected to the first node and a data voltage; a third transistor connected to a high-potential voltage and the fifth node; a fourth transistor connected to the fifth and third nodes; and a fifth transistor connected to the first node and a second voltage.