Display Panel Test Pad Layout for Accurate Contact Resistance
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Solution Overview
Problem
Existing display devices face challenges in accurately measuring contact resistance between pads and leads, leading to potential pixel defects due to inaccurate voltage application, as the resistance of the display panel itself is not accurately accounted for in current measurement methods.
Innovation Solution
The design includes a system with dummy electrodes and specific test pads and lines that allow for precise measurement of contact resistance by isolating the panel's resistance factor, ensuring accurate voltage application and preventing pixel defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact resistance is measured using conventional methods without isolating panel resistance, then measurement process is simple, but measurement precision deteriorates due to inaccurate contact resistance values
Solution Approach 1:
The inspection circuit is segmented into multiple independent test pads (first test pad, second test pad, third test pad) that can measure different resistance components separately. This allows the panel resistance to be measured independently from the contact resistance, enabling accurate calculation of contact resistance by subtracting the panel resistance component from the total measured resistance.
Solution Approach 2:
Dummy electrodes are introduced as intermediary elements that provide additional measurement paths. The dummy electrodes connect to the inspection leads and enable the construction of multiple measurement equations, which are then solved simultaneously to isolate and calculate the contact resistance value accurately.
2Reliability
If voltage is applied without accurate contact resistance measurement, then device operation is simple, but reliability deteriorates due to pixel defects from inaccurate voltage application
Solution Approach 1:
The contact resistance and panel resistance are measured and calculated before the actual display operation. This preliminary measurement allows the system to determine accurate voltage values that will be applied to the display panel, preventing pixel defects caused by voltage errors due to contact resistance variations.
Solution Approach 2:
The measured resistance values are used to provide feedback for adjusting the voltage application parameters. By continuously monitoring and calculating the actual contact resistance, the system can compensate for variations and maintain reliable operation, preventing pixel defects through adaptive voltage control.
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
This approach enables precise measurement of contact resistance between pads and leads, preventing pixel defects by accurately determining the voltage values applied from the driving integrated circuit to the panel pads and lead lines, thus enhancing display performance.
Implementation Method 1
a contact resistance between the pad and the lead may be measured by measuring a contact resistance between an inspection pad located on the same layer as the pads and an inspection lead located on the same layer as the leads
Data Source
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AI summary
An inspection method of a display device which includes first through fourth panel test pads and a first substrate including 1-1, 1-2, 1-3 and 1-4 circuit test leads is disclosed. The method involves bringing jigs into contact with the first and second test points to obtain a first measured value; bringing the jigs into contact with the second and third test points to obtain a second measured value; bringing the jigs into contact with the first test point and third test points to obtain a third measured value; and determining each of the contact resistance between the panel test pads and the circuit test leads from these measurements.