Display Driver Fault Evaluation via Connected and Disconnected State Testing
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Solution Overview
Problem
As the number of channels and interconnection pitches in liquid crystal display devices increase, independent testing of display devices becomes difficult, making it challenging to identify defective components during pre-shipping testing, leading to the need for testing after the display driver and panel are connected.
Innovation Solution
A display driver with a test control unit, voltage converter, and fault evaluator that generates and supplies test data to identify faults by comparing pixel drive voltages in both connected and disconnected states, allowing for separate evaluation of driver and panel faults without disconnecting them.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If independent testing of display device is performed, then fault identification accuracy is improved, but device complexity increases due to additional testing equipment and processes
Solution Approach 1:
The patent combines the display driver and display panel into a single integrated testing unit. The driver outputs test signals that are fed back through the panel and returned to the driver for evaluation, eliminating the need for separate independent testing equipment while maintaining fault identification accuracy.
Solution Approach 2:
The display driver serves multiple functions: it acts as both the normal operating controller and the test signal generator/evaluator. The same driver circuitry used for driving the display during normal operation is also used to generate test signals and evaluate fault conditions, reducing the need for dedicated testing equipment.
2Device complexity
If testing is performed after connecting display driver and panel, then device complexity is reduced, but fault localization capability deteriorates
Solution Approach 1:
The patent segments the testing process into distinct phases: connected-state testing for panel fault detection and disconnected-state testing for driver fault detection. By controlling the connection state between driver and panel, the system can isolate and identify faults in each component separately despite being integrated.
Solution Approach 2:
The system dynamically changes the connection state between the driver and panel during testing. The driver can switch between connected-state (for panel testing) and disconnected-state (for driver testing), allowing flexible fault localization without requiring separate fixed testing configurations.
3Productivity
If multiple channels are used with finer interconnection pitches, then productivity is improved, but testing difficulty increases
Solution Approach 1:
The display driver performs self-testing by generating test signals and evaluating its own output and the panel response. This self-service capability eliminates the need for complex external testing equipment, making testing as easy as the normal driving operation regardless of the number of channels or interconnection pitch.
Data Source
AI summary
A display driver for driving a display panel includes a test control unit that generates n test data each designating a brightness gradation for each pixel of the panel, and controls a connected-state test for testing the display panel in a connected-state where the display panel and the display driver are electrically connected and a disconnected-state test for testing the display driver in a disconnected-state where the display panel and the display driver are electrically disconnected, a voltage converter that generates n pixel drive voltages from the n test data, an output unit that supplies each of the n pixel drive voltages to a corresponding data line in the connected-state, and a fault evaluator that outputs a test result signal including a fault or a no-fault in the connected-state and the disconnected-state by checking if each of the n pixel drive voltages is within an acceptable gradation voltage range.