Display Pixel Circuit Threshold Voltage Correction
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Solution Overview
Problem
Current active matrix type flat panel emissive display devices face challenges in achieving high precision due to variations in threshold voltages and mobilities of transistors, affecting emission luminance and image quality, and require complex pixel circuits for correction.
Innovation Solution
A display device and driving method that simplify the pixel circuit by using switching pulses as power supply voltage, reducing the number of constituent elements and wirings, and incorporating threshold voltage and mobility correction functions, allowing for reliable threshold voltage correction without being affected by wiring capacitance and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If correction functions are added to control emission luminance uniformly, then luminance uniformity is improved, but pixel circuit complexity increases
Solution Approach 1:
The patent combines the correction function with the existing pixel circuit components by integrating correction transistors and capacitors into the standard pixel structure. The correction circuit shares wiring and transistors with the driving circuit, merging multiple functions into a unified circuit design that achieves luminance uniformity without proportionally increasing complexity
Solution Approach 2:
The pixel circuit is designed to perform multiple functions: normal display driving, threshold voltage correction, and luminance compensation. By making the circuit multi-functional through shared components and multi-purpose transistors, the patent achieves correction capabilities without adding completely separate correction circuits, thus improving luminance uniformity while controlling circuit complexity
2Device complexity
If switching pulses are used as power supply voltage, then pixel circuit complexity is reduced, but threshold voltage correction stability is improved
Solution Approach 1:
The patent applies preliminary action by performing threshold voltage correction before the actual display operation. The correction is executed in advance during initialization phases, ensuring that threshold voltage variations are compensated before they affect display quality. This timing strategy allows the simplified circuit to achieve stable correction results without requiring complex real-time correction mechanisms
3Measurement precision
If wiring capacitance and resistance are reduced, then correction function accuracy is improved, but pixel circuit elements are reduced
Solution Approach 1:
The patent extracts and eliminates unnecessary wiring and circuit elements from the pixel circuit design. By carefully analyzing the correction function requirements, the invention removes redundant connections and components that contribute to capacitance and resistance, keeping only the essential elements needed for accurate threshold voltage correction. This extraction process reduces wiring capacitance and resistance while maintaining correction accuracy with fewer circuit elements
Data Source
AI summary
A display device comprises a pixel array unit including a plurality of pixels, and power supply lines and a power supply scanner for supplying a power supply voltage switching between first and second potentials to each of the power supply lines, wherein each of the pixels includes a light emitting element, a sampling transistor, a driver transistor, and a holding capacitor. The sampling transistor samples a signal potential to be held in the holding capacitor, the driver transistor receives a supply of a current from the power supply scanner through the power supply line at a first potential and flows a drive current to the light emitting element in accordance with the held signal potential, and the power supply scanner changes the power supply line from the first potential to the second potential before the sampling transistors samples the signal potential.