Built-in Light Sensor Test Unit for Display Panel Reliability
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Solution Overview
Problem
Built-in light sensors in display panels are difficult to test, leading to reliability issues in display panels, as existing techniques for testing these sensors do not exist, and omitting the test process decreases the reliability of the display panel.
Innovation Solution
A light sensor test unit comprising a test circuit, test pixel part, brightness measurer, and controller that applies a driving signal to selected pixels in the display panel to display a gray-scale corresponding to the external light intensity, allowing the brightness to be measured and compared to a predetermined reference to determine if the light sensor is operating correctly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an external type light sensor is used, then it is easier to test the light sensor operation, but the LCD size increases and the assembling process becomes complicated
Solution Approach 1:
The light sensor is merged with the display panel by forming it through a thin film process on the display panel during the same manufacturing process. This integration allows the light sensor to be tested easily while avoiding increased LCD size and complicated assembling processes, as the sensor becomes an inherent part of the panel structure.
Solution Approach 2:
The display panel structure is designed to serve multiple functions: it acts as both the display element and the substrate for the light sensor. The thin film process enables the light sensor to be formed on the display panel, making the panel itself a universal component that integrates both display and sensing functions.
2Device complexity
If a built-in type light sensor is used, then the LCD size is reduced and assembling is simplified, but it becomes difficult to test the light sensor operation
Solution Approach 1:
A test pixel part is provided in advance within the display panel structure, specifically designed for testing the light sensor. This preliminary arrangement of test components allows the built-in light sensor to be tested easily after integration, without requiring disassembly or complex external testing equipment.
Solution Approach 2:
The test pixel part acts as an intermediary element between the built-in light sensor and the testing process. By providing this intermediate test structure, the patent enables easy testing of the integrated light sensor without compromising the simplified assembling process or increasing device complexity.
3Ease of manufacture
If the test process of the built-in type light sensor is omitted, then the manufacturing process is simplified, but the reliability of the display panel decreases
Solution Approach 1:
The display panel includes self-testing capabilities through the integrated test pixel part and light sensor. This self-service feature allows the panel to verify its own functionality during or after manufacturing, ensuring reliability without requiring complex external testing procedures that would complicate the manufacturing process.
Solution Approach 2:
The test pixel part provides feedback functionality by allowing the light sensor to be tested in situ. This feedback mechanism ensures that the light sensor is functioning correctly, maintaining display panel reliability while keeping the manufacturing process relatively simple through integrated self-verification.
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 effective testing of built-in light sensors, ensuring their normal operation and enhancing the reliability of display panels by measuring the brightness of the test pixels and comparing it to a reference, thereby validating the sensor's functionality.
Implementation Method 1
a light sensor which is built in a display panel to sense an external light
Implementation Method 2
The LCD is classified into two types according to the light used to display the image. That is, the LCD is classified into a transmissive LCD which uses an internal light generated from an inner light source to display the image
Data Source
AI summary
In a light sensor test unit, a test circuit is built in a display panel and connected to an output node of a light sensor which senses an intensity of an external light. When external light having a predetermined intensity is provided to the light sensor, the test circuit outputs a driving signal in response to a sensing signal output from the output node. A test pixel part includes pixels selected from a plurality of pixels arranged in the display panel and receives the driving signal from the test circuit to display a gray-scale corresponding to the driving signal. A brightness measurer measures a brightness corresponding to the gray-scale displayed in the test pixel part to compare the measured brightness with a predetermined brightness, thereby testing whether the light sensor built in the display panel is normally operated.