Display Device Auxiliary Transistor Kickback Voltage Compensation
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Solution Overview
Problem
Display devices with self-light emitting elements face issues with kickback voltage affecting gate voltage, leading to inefficient image display due to the use of PMOS transistors, and there is a need to prevent gate voltage drops without significant layout modifications.
Innovation Solution
A display device design incorporating a combination of PMOS and NMOS transistors, where an auxiliary PMOS transistor is used to compensate for kickback voltage effects, preventing gate voltage drops by using a series connection of PMOS and NMOS transistors between the second electrode and the gate electrode of a driving transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PMOS transistors are used in display devices, then the device can operate with existing layouts, but kickback voltage causes gate voltage drops leading to inefficient image display
Solution Approach 1:
An auxiliary transistor is introduced as an intermediary component between the driving transistor and the light emitting element. This auxiliary transistor compensates for the kickback voltage effect by providing an additional current path, thereby preventing gate voltage drops and improving image display efficiency without requiring layout modifications
Solution Approach 2:
The invention changes the electrical parameters of the pixel circuit by adding the auxiliary transistor, which alters the current-voltage characteristics and compensates for the harmful kickback voltage effect. This parameter change enables the circuit to maintain stable gate voltage despite the presence of kickback voltage
2Reliability
If NMOS transistors are used instead of PMOS transistors, then kickback voltage characteristics may improve, but the transistor type change requires significant layout modifications
Solution Approach 1:
The pixel circuit is segmented into multiple functional blocks: driving transistor, auxiliary transistor, and light emitting element. This segmentation allows the auxiliary transistor to be added as a separate functional unit without requiring redesign of the entire circuit layout, thus improving kickback voltage characteristics while maintaining manufacturing ease
Solution Approach 2:
The auxiliary transistor serves multiple functions: it compensates for kickback voltage, provides an additional current path, and maintains compatibility with existing PMOS-based layouts. This multi-functionality allows the circuit to achieve improved kickback voltage characteristics without requiring conversion to NMOS transistors or significant layout changes
Data Source
AI summary
A display device includes a light emitting element. A first transistor transmits a driving current to the light emitting element. A second transistor is connected to a first electrode of the first transistor to transmit a data signal. A third transistor has a first electrode connected to a second electrode of the first transistor. An auxiliary transistor is connected between a second electrode of the third transistor and a gate electrode of the first transistor to transmit the data signal to the gate electrode of the first transistor. Each of the first transistor, the second transistor and the auxiliary transistor is a first-type transistor, and the third transistor is a second-type transistor different from the first-type transistor.