Stretchable Display Pixel Circuit with Threshold Voltage Compensation
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Solution Overview
Problem
Existing pixel circuits in stretchable display devices face challenges in maintaining stable operation and reliable performance when the display panel is deformed, particularly due to issues with threshold voltage deviation and power source voltage drop, which can lead to short-circuiting and reduced elongation capabilities.
Innovation Solution
A pixel circuit design that includes a compensation circuit connected to data and gate lines, with switch elements and a driving element, allowing for stable current generation and initialization without short-circuiting, even under deformation, by using a series connection of a light-emitting element, driving element, and switch element, and employing a compensation circuit to alternately receive voltages through the data line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional pixel circuit is used in a stretchable display device, then the display can be deformed, but the circuit operation becomes unstable due to threshold voltage deviation and power source voltage drop
Solution Approach 1:
The compensation circuit performs preliminary action by storing the threshold voltage of the driving transistor in a capacitor before the light-emitting element is driven. This preliminary storage of voltage information allows the circuit to compensate for threshold voltage deviations that occur during deformation, maintaining stable operation without requiring complex real-time sensing mechanisms.
Solution Approach 2:
The compensation circuit implements feedback by continuously monitoring and storing the actual threshold voltage of the driving transistor, then using this stored information to adjust and compensate for voltage drops and threshold deviations during operation. This feedback mechanism ensures reliable circuit operation even when the display is stretched or deformed.
2Reliability
If more wires and circuit components are added to compensate for deformation, then circuit stability improves, but device complexity increases
Solution Approach 1:
The compensation circuit serves multiple functions using the same hardware components: it stores threshold voltage, compensates for power source voltage drops, and maintains proper operation during deformation. By making the compensation circuit multi-functional, the patent avoids adding separate dedicated circuits for each compensation need, thereby reducing overall device complexity while maintaining reliability.
Solution Approach 2:
The patent merges the compensation functionality into the existing pixel circuit structure, combining the compensation circuit with the driving element and light-emitting element in an integrated manner. This merging approach eliminates the need for separate standalone compensation circuits, reducing wire count and overall device complexity while achieving the desired stability.
3Adaptability or versatility
If the pixel circuit is simplified to reduce wire count, then elongation capability improves, but threshold voltage compensation becomes insufficient
Solution Approach 1:
The driving transistor itself serves the dual purpose of both driving the light-emitting element and providing the threshold voltage information for compensation. The compensation circuit utilizes the inherent electrical characteristics of the driving transistor without requiring separate sensing transistors or additional measurement components, thereby maintaining compensation accuracy while minimizing circuit complexity and preserving elongation capability.
Data Source
AI summary
A pixel circuit includes: a compensation circuit connected to a data line, a first gate line, and a second gate line, and configured to receive first and second voltages alternately through the data line, a first gate signal through the first gate line, and a second gate signal through the second gate line; a light-emitting element; a driving element including a gate electrode configured to receive the second voltage via the compensation circuit, the driving element being configured to generate a current to drive the light-emitting element; and a switch element including a gate electrode configured to receive the second gate signal via the compensation circuit, and configured to switch a path of the current between the driving element and the light-emitting element. The light-emitting element, the driving element, and the switch element may be connected in series between a first power line and a second power line.