Driving Transistor Reset in Pixel Circuits for Stable Luminance
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Solution Overview
Problem
The AMOLED display screen experiences hysteresis phenomena in pixel circuits, leading to issues such as short-term residual images and slow responses due to characteristic shifts in driving transistors when operating at certain bias voltages.
Innovation Solution
A pixel circuit with a driving circuit, data writing circuit, reset circuit, and additional components like compensation control and initialization circuits, which utilize specific scanning signals to control connections and apply opposite bias voltages during compensation phases to counteract characteristic shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the driving transistor operates at a certain bias voltage for a certain time period, then the display can maintain stable operation, but the characteristic of the transistor shifts causing hysteresis phenomenon
Solution Approach 1:
The patent applies preliminary action by introducing a reset circuit that performs a reset operation before the driving transistor operates at the certain bias voltage. This preliminary reset action eliminates the hysteresis phenomenon and characteristic shifts that would otherwise occur during operation, allowing the transistor to start from a known state and maintain stable characteristics throughout the operation period.
2Duration of action of stationary object
If the driving transistor operates continuously, then the display can maintain image quality, but short-term residual images and slow responses occur due to characteristic shifts
Solution Approach 1:
The reset circuit performs a preliminary reset operation before the driving transistor begins continuous operation at the certain bias voltage. This preliminary action prevents the generation of short-term residual images and slow responses by eliminating hysteresis effects at the start of operation, allowing continuous operation to proceed without these harmful artifacts.
Solution Approach 2:
The patent converts the harmful hysteresis phenomenon and characteristic shifts into a beneficial controlled process by using the reset circuit to deliberately reset the transistor state before operation. This transforms the potentially harmful continuous characteristic drift into a controlled, predictable behavior that can be managed through the reset mechanism.
3Reliability
If a reset circuit is added to compensate for characteristic shifts, then hysteresis phenomenon is reduced, but device complexity increases
Solution Approach 1:
The patent merges the reset circuit with the existing pixel circuit structure, integrating the reset functionality into the overall circuit architecture rather than adding it as a completely separate system. This merging approach reduces the increase in device complexity by sharing components and integrating the reset operation into the existing timing and control framework.
Solution Approach 2:
The reset circuit is designed to automatically reset the driving transistor based on the operation timing and control signals already present in the pixel circuit. This self-service mechanism eliminates the need for external complex control systems, as the reset operation is triggered naturally by the existing circuit's timing signals and operational state.
Data Source
AI summary
A pixel circuit and a driving method thereof, a display substrate, and a display device are provided. In the pixel circuit, a data writing circuit is configured to control a connection between a data line and a second terminal of a driving circuit under control of a first scanning signal provided by a first scanning line; a reset circuit is configured to control a connection between a reset voltage line and the second terminal of the driving circuit under control of a third scanning signal provided by a third scanning line; or the reset circuit is coupled to the third scanning line, the reset voltage line and a first terminal of the driving circuit, and is configured to control a connection between the reset voltage line and the first terminal of the driving circuit under control of the third scanning signal.