Testable Data Driver with Switching Circuit for Display Devices
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Solution Overview
Problem
Display devices may fail to display desired images if the data driver has defects, necessitating effective testing and monitoring of output signals.
Innovation Solution
A display device configuration that includes a display panel, a gate driver, a data driver, and a driving control unit, with a digital-to-analog converter and a switching circuit that allows for normal and test modes, enabling the connection of pads to output terminals and buffers for signal testing, and a test control unit to manage selection signals and clock synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a data driver is designed with all pads connected to output terminals simultaneously during normal mode, then the display operation is efficient and simple, but testing the data driver becomes complex and requires more testable pads
Solution Approach 1:
The switching circuit dynamically reconfigures the connection between output terminals and pads based on operating mode. During normal mode, all output terminals are connected to corresponding pads simultaneously for efficient display operation. During test mode, the switching circuit reconfigures to connect only specific groups of output terminals to pads in sequential time periods, enabling simplified testing while maintaining normal operation efficiency
Solution Approach 2:
The switching circuit operates periodically, switching between normal mode and test mode based on control signals. In test mode, it sequentially connects different groups of output terminals to pads in different time periods (first time period, second time period), allowing systematic testing of the data driver without requiring all pads to be testable simultaneously
2Reliability
If the switching circuit connects all output terminals to pads simultaneously, then all data lines can be tested at once, but the number of required testable pads increases
Solution Approach 1:
The switching circuit divides testing into periodic phases where different groups of output terminals are connected to pads in sequential time periods. During the first time period, a first group of output terminals connects to pads; during the second time period, a second group connects. This temporal multiplexing ensures complete testing coverage while using a limited number of physical pads
Solution Approach 2:
The same set of pads serves multiple functions: they act as data input terminals during normal display operation and as test output terminals during different testing phases. The switching circuit enables pads to be universally used for both driving display pixels and receiving test signals, eliminating the need for dedicated test pads
3Area of stationary object
If the data driver IC size is minimized, then the overall display device size is reduced, but the number of testable pads is limited
Solution Approach 1:
By implementing time-sequential switching of pad connections, the data driver IC can provide comprehensive testing capability with a reduced number of physical pads. The switching circuit multiplexes the limited pads across different output terminals at different time periods, maintaining full testing coverage while minimizing the IC area required for pad structures
Solution Approach 2:
The pads are designed to serve dual purposes: normal data transmission during display operation and test signal reception during testing modes. This multi-functionality reduces the need for separate dedicated test pads, thereby minimizing the overall IC size while preserving complete testing capability
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
Enables efficient testing of data drivers by switching between normal and test modes, allowing for the identification of defects and ensuring proper image display, while minimizing the size of the data driver ICs and reducing the number of testable pads.
Implementation Method 1
The digital-to-analog converter is configured to convert the data signal into a plurality of analog signals corresponding to each of the plurality of data lines
Data Source
AI summary
A display device includes a display panel, a gate driver, a data driver, and a driving control unit. The display panel includes pixels connected to a corresponding one of gate lines and a corresponding one of data lines. The gate driver drives the gate lines. The data driver includes first pads and second pads. The first pads are connected to each of first data lines of the data lines, and the second pads are connected to each of second data lines of the data lines. The driving control unit provides control signals and a data signal to the data driver, and to control the gate driver. The data driver includes a digital-to-analog converter and a switching circuit. The digital-to-analog converter converts the data signal into analog signals. The switching circuit sequentially outputs the analog signals to the first pads during a test mode.