Display Pixel Circuit Saturation Driving for Luminance Uniformity
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Solution Overview
Problem
Conventional analog-type driving methods for display devices increase the number of circuit elements in pixels, making them unsuitable for large-sized or high-resolution panels, and digital driving methods suffer from luminance uniformity issues due to operating transistors in a linear area, leading to display quality deterioration.
Innovation Solution
A digital driving method that operates the driving transistor in a saturation area, using a pixel circuit with reduced elements, including a compensation transistor and capacitor, to maintain luminance uniformity and simplify layout design, while applying a bias voltage to ensure high integration and high resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a digital driving method is used to reduce the number of circuit elements in a pixel, then high integration and high resolution can be realized, but luminance uniformity deteriorates because the driving transistor operates in a linear area
Solution Approach 1:
The patent changes the operating region parameter of the driving transistor from linear area to saturation area by adjusting the gate voltage through the compensation transistor. This parameter change enables the transistor to operate in a region where drain current is primarily controlled by gate voltage rather than drain voltage, achieving both high integration and luminance uniformity.
Solution Approach 2:
The compensation transistor acts as an intermediary component between the data line and the driving transistor's gate electrode. It introduces an additional voltage control path that compensates for the linear region operation effects, allowing the driving transistor to achieve saturation region operation while maintaining luminance uniformity across the display panel.
2Productivity
If the driving transistor operates in a linear area to enable digital driving, then circuit integration is improved, but display quality deteriorates due to luminance non-uniformity
Solution Approach 1:
The patent changes the operating region parameter of the driving transistor from linear area to saturation area by adjusting the gate voltage through the compensation transistor. This parameter change enables the transistor to operate in a region where drain current is primarily controlled by gate voltage rather than drain voltage, achieving both high integration and luminance uniformity.
Solution Approach 2:
The compensation transistor provides a feedback mechanism by monitoring and adjusting the gate voltage of the driving transistor based on the data signal level. This feedback control ensures that the driving transistor operates in the saturation region while maintaining uniform luminance output, thereby improving display quality without sacrificing circuit integration.
3Ease of operation
If a conventional pixel circuit with 7-8 transistors and 2-3 capacitors is used, then analog driving is achieved, but layout design and manufacturing become difficult for large-sized panels
Solution Approach 1:
The patent extracts and removes unnecessary circuit elements from the conventional pixel circuit structure. By eliminating redundant transistors and capacitors that are not needed for digital driving functionality, the circuit is simplified to 2-3 transistors and 1 capacitor, making it suitable for large-sized panel manufacturing while maintaining driving capability.
Solution Approach 2:
The simplified pixel circuit structure performs multiple functions: the switching transistor controls signal input, the compensation transistor enables saturation region operation and luminance uniformity, and the storage capacitor maintains data voltage. This multi-functional design achieves analog-like performance with digital driving simplicity, facilitating ease of manufacture for large panels.
Data Source
AI summary
A pixel, a display device including the same, and a driving method thereof. The display device includes: a data driver transmitting data signals; a scan driver generating and transmitting scan signals; a display panel including pixels, each emitting light with a driving current according to the data signals; a compensation signal unit generating and transmitting a compensation control signal for controlling simultaneous transmission of a predetermined bias voltage to each of the pixels before a data voltage according to the data signals is applied to each of the pixels; a power controller controlling voltage levels of the first power source voltage and the second power source voltage and supplying the level-controlled first and second power source voltages; and a timing controller generating the data signals by processing an external image signal and generating a plurality of driving control signals.