N-Type PWM Pixel Circuit With Threshold Compensation
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Solution Overview
Problem
Conventional pixel circuits driven in pulse width modulation with internal threshold voltage compensation require nineteen or more transistors and three or more capacitors, limiting their application to ultra-high resolution display apparatus and suffering from afterimage, response time, and luminance-changing-rate degradation due to P-type transistors.
Innovation Solution
A pixel circuit design utilizing fewer transistors, specifically ten transistors and two capacitors, including only N-type transistors, which enables internal threshold voltage compensation and supports ultra-high resolution displays by enhancing afterimage, response time, and luminance-changing-rate characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pixel circuits with nineteen or more transistors and three or more capacitors are used for internal threshold voltage compensation in pulse width modulation, then threshold voltage compensation is achieved, but device complexity and integration difficulty increase
Solution Approach 1:
The patent extracts and eliminates redundant components from the conventional pixel circuit. By removing unnecessary transistors and capacitors while retaining the essential threshold voltage compensation function through a streamlined circuit architecture, the design achieves the same reliability with significantly reduced complexity (10 transistors and 2 capacitors).
Solution Approach 2:
The patent merges multiple functions into fewer components. The simplified circuit structure combines threshold voltage compensation, pixel driving, and signal control functions into a more integrated architecture, reducing the total component count while maintaining functional completeness.
2Ease of operation
If P-type transistors are used in pulse width modulation pixel circuits, then circuit operation is achieved, but afterimage characteristic, response time, and luminance-changing-rate performance deteriorate
Solution Approach 1:
The patent changes the fundamental parameter of transistor type from P-type to N-type. This parameter change fundamentally alters the electrical characteristics of the pixel circuit, improving afterimage elimination, response time, and luminance changing rate while maintaining proper circuit operation through adjusted voltage levels and driving schemes.
3Manufacturing precision
If pixel circuits with high transistor count are used for ultra-high resolution display, then display resolution is achieved, but manufacturing integration becomes limited
Solution Approach 1:
The patent extracts and removes excess components from the pixel circuit design. By eliminating redundant transistors and capacitors, the circuit occupies less area and is easier to manufacture at high resolutions, while still achieving ultra-high display resolution through the optimized circuit architecture.
Solution Approach 2:
The patent designs universal circuit blocks that can be scaled for ultra-high resolution displays. The simplified pixel circuit structure with 10 transistors and 2 capacitors serves as a universal building block that maintains manufacturing feasibility even when densely packed for high-resolution applications.
Data Source
AI summary
A pixel circuit includes a first transistor including a control electrode connected to a first node, a first electrode connected to a second node, and a second electrode connected to a third node, a second transistor connected to the first node and the second node, a third transistor configured to apply a data voltage to the first transistor, a seventh transistor connected to a fourth node, and configured to apply a driving current to a light-emitting element, a ninth transistor configured to apply a constant-current voltage to the fourth node, and the light-emitting element configured to emit a light based on the data voltage and the constant-current voltage, wherein the first transistor, the second transistor, the third transistor, the seventh transistor, and the ninth transistor include N-type transistors.