Pixel Circuit Threshold Voltage Correction Without Transistor Increase
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Solution Overview
Problem
Increasing the number of transistors in a pixel circuit to reduce threshold voltage correction time leads to an increase in pixel circuit size, hindering miniaturization and speeding up the driving of the pixel circuit.
Innovation Solution
A pixel circuit configuration including a drive transistor, light-emission control transistor, reset transistors, and capacitive elements, with a specific driving method that involves setting and correcting the threshold voltage of the drive transistor without increasing the number of transistors, utilizing P-channel transistors and capacitive elements to manage signal voltages and potentials efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the number of transistors in a pixel circuit is increased to reduce threshold voltage correction time, then the correction speed is improved, but the pixel circuit size increases
Solution Approach 1:
The patent applies preliminary action by performing threshold voltage correction in advance during the initialization period before the light emission period. The correction is executed by controlling the second reset transistor to connect the drain node to the gate node during a predetermined period, preparing the drive transistor's threshold voltage before actual display operation begins. This allows the correction to be completed beforehand without extending the light emission time or requiring additional transistors.
Solution Approach 2:
The patent makes the second reset transistor perform multiple functions: it serves as both a reset transistor for initializing the gate node potential and as a threshold voltage correction transistor by controlling the connection between drain node and gate node. This multi-functionality eliminates the need for separate correction transistors, maintaining the pixel circuit size while enabling threshold voltage correction capability.
2Area of stationary object
If the pixel circuit size is reduced for miniaturization, then the definition is improved, but the threshold voltage correction capability may be compromised
Solution Approach 1:
The second reset transistor is designed to perform dual functions: resetting the gate node potential to a reference level and correcting the threshold voltage by controlling the connection between drain node and gate node. This multi-functional design maintains full threshold voltage correction capability within the existing transistor count, enabling pixel circuit miniaturization without sacrificing correction reliability.
Solution Approach 2:
The patent changes the operational parameters of the second reset transistor by controlling its on/off timing and the potential levels applied to its terminals. By adjusting these parameters during different periods (initialization period vs. light emission period), the transistor achieves both reset and threshold voltage correction functions, maintaining reliability while reducing circuit size.
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 configuration allows for the rapid correction of the threshold voltage of the drive transistor, speeding up the pixel circuit's driving process without enlarging the pixel circuit, thus enabling miniaturization and higher definition in display devices.
Implementation Method 1
a capacitive element provided between a signal line to which the signal voltage is applied and a source node of the write transistor
Data Source
AI summary
A pixel circuit is provided including a light-emitting element, a drive transistor that supplies a current to the light-emitting element, a light-emission control transistor that controls connection between a drain node of the drive transistor and an anode of the light-emitting element, and a first reset transistor that sets a potential of the anode of the light-emitting element to a predetermined potential. The pixel circuit further includes a second reset transistor that controls connection between a drain node of the drive transistor and a gate node of the drive transistor, a write transistor that controls writing of a signal voltage at the gate node of the drive transistor, and a capacitive element provided between a signal line to which the signal voltage is applied and a source node of the write transistor.