LED Display Pixel Internal Test Circuit Design
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Solution Overview
Problem
Existing light-emitting diode (LED) display pixels require complex signal transmission for testing, which can be challenging due to the need for adapting signals to the specific configuration of the driving circuit.
Innovation Solution
A display pixel design that includes a dual-module electronic driving circuit, where a first module activates or deactivates a second module based on supply voltage and signal inputs, allowing for internal test operations without external signal adaptation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex external signal transmission is used for testing display pixels, then test operations can be performed, but the device complexity and difficulty of operation increase
Solution Approach 1:
The display pixel performs self-testing through internal test circuits that generate test signals locally. The pixel activates its own test mode by detecting specific voltage conditions on its conductive pads, eliminating the need for external test equipment to generate and transmit complex test signals. This self-service approach simplifies the testing process while maintaining reliable test capability.
Solution Approach 2:
The same conductive pads used for normal display operation are also used for test operations. The electronic driving circuit is designed to function in both normal display mode and test mode, with the ability to detect test conditions and switch between modes. This multi-functionality reduces the need for separate test interfaces and simplifies the overall system.
2Ease of manufacture
If display pixels are designed with embedded driving circuits (smart pixels), then manufacturing is simplified, but test operations become more complex due to circuit configuration dependencies
Solution Approach 1:
The smart pixel's embedded driving circuit includes self-testing capability. The circuit automatically detects when it is in test mode by monitoring the voltage conditions on its conductive pads and activates internal test signal generation. This eliminates the need for external equipment to understand or adapt to the specific circuit configuration, making testing as easy as manufacturing.
Solution Approach 2:
Instead of having external test equipment adapt to the pixel's circuit configuration, the pixel's driving circuit is designed to generate and respond to test signals internally. The circuit inverts the traditional testing approach by making the device under test the source of test signals rather than the recipient, thereby simplifying the operation for the user.
3Device complexity
If the number of conductive pads is reduced in display pixels, then device size and complexity are reduced, but test operation capability may be limited
Solution Approach 1:
The conductive pads are designed to serve multiple functions: they carry power and data signals during normal operation and simultaneously serve as test signal inputs and outputs when test mode is activated. The driving circuit detects test mode through voltage conditions on these same pads and switches to internal test signal generation, maintaining full test capability with fewer physical pads.
Solution Approach 2:
The patent combines the normal operation interfaces and test interfaces into a single set of conductive pads. The same physical pads that receive power and data during display operation are also used for test signal transmission. The driving circuit merges the control logic for both modes, allowing the system to switch between normal and test operations without requiring separate physical interfaces.
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
Simplifies the test operation process by allowing the display pixel to perform internal testing without the need for complex external signal transmission, reducing the number of conductive pads and enhancing operational efficiency.
Implementation Method 1
at least one light-emitting diode and one electronic circuit for driving said light-emitting diode
Data Source
AI summary
A display pixel comprising at least one light-emitting diode, an electronic circuit for driving the light-emitting diode, and first and second conductive pads, the first pad being coupled to the light-emitting diode, the driving circuit being configured in normal operation to drive the light-emitting diode on the basis of first signals received on the second pad, the driving circuit comprising first and second modules, the first module being coupled to the first and second pads, and being configured to activate or deactivate the second module on the basis of the supply voltage received on the first pad and first signals received on the second pad, the second module being configured, when activated, to deliver second signals for driving the light-emitting diode for a test operation.