Pixel Circuit Leakage Current Reduction via Reset Isolation
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Solution Overview
Problem
Certain pixel circuits experience leakage current during reset operations, leading to high power consumption and potential image quality issues due to incomplete reset.
Innovation Solution
The pixel circuit design includes a driving transistor, storage capacitor, and multiple transistors that electrically isolate the path between the system high voltage terminal and the reference voltage terminal during the reset period, preventing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reset operation is performed in the pixel circuit, then the voltage at the control end of the driving transistor is reset, but leakage current flows from the high voltage terminal to the reference voltage terminal causing high power consumption
Solution Approach 1:
The pixel circuit is divided into distinct operational phases: a reset period where the reset transistor is turned on to reset the driving transistor, and an emission period where the reset transistor is turned off. This temporal segmentation allows the circuit to achieve complete reset while preventing leakage current during the emission phase, thus resolving the contradiction between reset completeness and power consumption.
Solution Approach 2:
The reset transistor is controlled to operate periodically - turned on during the reset period to reset the driving transistor, and turned off during the emission period to block leakage current. This periodic switching action enables the circuit to achieve both complete reset functionality and low power consumption by ensuring the reset transistor is off during periods when leakage would occur.
2Loss of energy
If the reset operation is performed with minimum brightness adjustment, then power consumption is reduced, but leakage current still occurs causing incomplete reset and affecting image quality
Solution Approach 1:
The reset operation is performed as a preliminary action before the emission period. The reset transistor is turned on during the reset period to completely reset the driving transistor's control end voltage before any emission occurs. This preliminary reset action ensures complete reset functionality is achieved before the circuit enters the low-power emission state, preventing image quality issues while maintaining low power consumption.
3Loss of energy
If the path between high voltage terminal and reference voltage terminal is isolated during reset period, then leakage current is prevented, but circuit complexity increases due to additional control mechanisms
Solution Approach 1:
The reset transistor serves multiple functions: it acts as a switch to isolate the path between high voltage and reference voltage terminals during the reset period, and simultaneously functions as a control element that can be turned off during the emission period to prevent leakage current. This multi-functionality allows the circuit to achieve low power consumption without significantly increasing circuit complexity, as the same transistor handles both reset and leakage prevention tasks.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively reduces power consumption by preventing leakage current during reset operations and ensures complete reset, thereby maintaining image quality.
Implementation Method 1
When the first transistor is turned on according to a first control signal, the storage capacitor resets the voltage at the control end of the driving transistor by capacitive coupling effect according to a voltage variation of the data signal
Data Source
AI summary
A pixel circuit includes a driving transistor, a storage capacitor, a first transistor, a second transistor, a third transistor and a fourth transistor. A first end of the driving transistor is electrically coupled to a system high voltage terminal. The driving transistor is configured to control a driving current supplied to a light emitting element. A first end of the storage capacitor is electrically coupled to a control end of the driving transistor. A first end of the first transistor is electrically coupled to a second end of the storage capacitor, and a second end of the first transistor is configured to receive a data signal. When the first transistor is turned on according to the first control signal, the storage capacitor resets a voltage at the control end of the driving transistor, by a capacitive coupling effect, according to a change in voltage of the data signal.