Source Driver Interpolation Method for Display Brightness Reversal
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Solution Overview
Problem
As scan rates of display panels increase, the brightness reversal phenomenon occurs due to differences in slew rates of gamma voltages input to unit buffers, which is not effectively addressed by increasing gamma line thickness or using a full-decoder scheme that increases the number of gamma lines.
Innovation Solution
A source driver with a buffer unit and decoder unit that inputs two or more gamma voltages with different magnitudes to unit buffers, using an interpolation method to output gradation voltages within a predetermined range, reducing the difference in slew rates and preventing brightness reversal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of gamma lines is increased to prevent brightness reversal, then the brightness reversal phenomenon is reduced, but the device complexity and chip size increase
Solution Approach 1:
The patent divides the gamma voltage input into multiple segments by providing different gamma voltages (first gamma voltage and second gamma voltage) to different input terminals of the unit buffer. This segmentation allows the system to prevent brightness reversal without requiring a full increase in the number of gamma lines, as the interpolation between segmented voltages achieves the desired effect with fewer physical lines.
Solution Approach 2:
The patent introduces a new dimension of control by applying multiple gamma voltages simultaneously to different input terminals of the same unit buffer. Instead of using more gamma lines (one-dimensional increase), the invention utilizes the multi-terminal input structure of the unit buffer (adding another dimension of voltage input) to achieve brightness reversal prevention while maintaining a compact gamma line configuration.
2Reliability
If gamma line thickness is increased to reduce brightness reversal, then the brightness reversal phenomenon is reduced, but the manufacturing complexity and device area increase
Solution Approach 1:
The patent changes the electrical parameters (voltage magnitudes and combinations) rather than physical parameters (line thickness). By adjusting which gamma voltages are applied to which input terminals and how the unit buffer interpolates them, the system prevents brightness reversal through electrical parameter optimization instead of increasing physical gamma line dimensions.
3Reliability
If a full-decoder scheme is used to address brightness reversal, then the brightness reversal phenomenon is reduced, but the device complexity and number of components increase
Solution Approach 1:
The patent applies partial action by using a simplified decoder configuration that provides only the necessary gamma voltages for interpolation, rather than a complete full-decoder scheme. The unit buffer's inherent interpolation capability performs the remaining function, allowing the system to achieve brightness reversal prevention with a partial decoder structure, thereby reducing overall device complexity.
4Reliability
If multiple gamma voltages are input to unit buffers to reduce slew rate differences, then the brightness reversal phenomenon is reduced, but the decoder unit complexity increases
Solution Approach 1:
The patent makes the unit buffer multi-functional by enabling it to accept multiple gamma voltages and perform both voltage selection and interpolation functions. This universality allows the decoder unit to be simplified, as the unit buffer itself becomes a versatile component that can handle multiple voltage inputs and generate the appropriate output, thereby reducing overall decoder complexity while achieving slew rate matching.
Data Source
AI summary
A source driver includes a buffer unit including a plurality of unit buffers corresponding to a plurality of source lines, where each of the plurality of unit buffers includes a plurality of input terminals and an output terminal connected to at least one of the plurality of source lines, and a decoder unit configured to receive image data and a plurality of gamma voltages, and input at least one of the plurality of gamma voltages to the plurality of input terminals of each of the plurality of unit buffers, using the image data. The decoder unit inputs two or more of the gamma voltages, having different magnitudes, to the plurality of input terminals of each of first unit buffers among the plurality of unit buffers, and the first unit buffers output a gradation voltage higher than a first voltage and lower than a second voltage.