Display Driver Gamma Line Defect Detection Using Complementary Transistors
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Solution Overview
Problem
Gamma lines in display driver integrated circuits (DDIs) can experience resistance variations due to manufacturing defects or short-circuits, leading to inaccurate data voltage delivery and poor image quality.
Innovation Solution
Incorporating first and second transistors of different types at the ends of gamma lines to measure resistance and current, using complementary signals to determine defects by comparing measured values against reference ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gamma lines are used to transmit gamma voltages from the gamma voltage generator to the source driver, then data voltage can be delivered to pixels, but resistance variations due to manufacturing defects or short-circuits cause inaccurate voltage delivery and poor image quality
Solution Approach 1:
The patent applies preliminary action by performing defect detection on gamma lines before final product shipment. A test mode is activated that applies test voltages to gamma lines and measures current values to identify resistance variations caused by manufacturing defects. This allows defective products to be screened out before reaching customers, ensuring reliable voltage delivery in normal operation mode.
Solution Approach 2:
The patent replaces physical inspection methods with electrical measurement. Instead of mechanical or visual inspection of gamma lines, the invention uses electrical current measurement to detect resistance variations. By applying test voltages and measuring current values through transistors connected to gamma lines, the system automatically identifies manufacturing defects without physical contact or complex mechanical testing equipment.
2Measurement precision
If traditional testing methods are used to screen defective gamma lines, then defect detection can be performed, but testing time is excessive and productivity is low
Solution Approach 1:
The patent merges the test transistor and drive transistor into a single integrated circuit structure. The test transistor shares the same physical substrate and connection pathways as the drive transistor, allowing defect detection to be performed using the existing display panel infrastructure. This integration eliminates the need for separate external testing equipment and reduces testing time while maintaining detection accuracy.
Solution Approach 2:
The patent implements self-service by enabling the display panel's own transistors and circuitry to perform the testing function. The test mode utilizes the existing gamma voltage generator, source driver, and transistor structures to conduct self-diagnosis. By activating test signals through the same hardware used for normal operation, the system performs automatic defect detection without requiring external testing apparatus, thereby improving productivity while maintaining measurement precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively identifies and screens out gamma lines with defects, ensuring accurate voltage delivery and high-quality image output.
Implementation Method 1
Gamma lines in display driver integrated circuits (DDIs) can experience resistance variations due to manufacturing defects or short-circuits
Implementation Method 2
applying a first test voltage to the first transistor, and applying a second test voltage to the second transistor; obtaining a current value of a current flowing to the gamma line
Data Source
AI summary
An example display driving integrated circuit includes a gamma voltage generator, a source driver, gamma lines, a first transistor, and a second transistor. The gamma voltage generator generates gamma voltages. The source driver generates data signals based on the gamma voltages. The gamma lines connect the gamma voltage generator with the source driver, and transmit the gamma voltages. The first transistor and the second transistor connect to a first end and a second end of a first gamma line of the gamma lines. The first transistor includes a first gate for receiving a first signal. The second transistor includes a second gate for receiving a second signal. The first signal and the second signal are complementary to each other.