Display Panel Test Lead Layout for Accurate Contact Resistance
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Solution Overview
Problem
Existing display device inspection methods fail to accurately measure contact resistance between pads and leads, leading to inaccurate determination of voltage values applied to pixels, which can cause pixel defects due to the inclusion of the display panel's resistance in the measurement.
Innovation Solution
The display device incorporates a design with panel test pads and test leads connected through test lines, allowing for precise measurement of contact resistance by isolating the display panel's resistance, using a resistance measuring device to calculate contact resistances between pads and leads, and removing the panel's resistance factor from the measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact resistance is measured using existing inspection methods, then measurement can be performed, but the measurement precision is poor due to inclusion of display panel resistance
Solution Approach 1:
The measurement system is segmented into separate test lead lines (first test lead line, second test lead line) that are electrically connected to the display panel through dedicated test pads. This segmentation allows the measurement path to be separated from the pixel circuit paths, enabling independent measurement of contact resistance without interference from display panel resistance.
Solution Approach 2:
Test pads (first panel test pad, second panel test pad) serve as intermediary elements between the test leads and the display panel circuitry. These intermediaries provide dedicated contact points that facilitate accurate contact resistance measurement while isolating the measurement process from the main pixel circuits, thereby preventing measurement errors that would otherwise lead to pixel defects.
2Ease of manufacture
If display panel resistance is included in the measurement, then measurement can be performed with simpler setup, but the measurement precision deteriorates
Solution Approach 1:
The test lead lines are segmented from the main pixel circuit lines and connected through dedicated test pads. This segmentation creates an independent measurement path that can be established during the manufacturing process without adding significant complexity, while accurately excluding display panel resistance from the contact resistance measurement.
3Productivity
If contact resistance measurement is not accurate, then inspection process remains simple, but pixel defects occur due to incorrect voltage application
Solution Approach 1:
The test pads and test lead lines are incorporated into the display panel structure during manufacturing, enabling contact resistance measurement to be performed as a preliminary inspection step before final assembly. This preliminary measurement ensures accurate voltage application parameters are established, preventing pixel defects while maintaining efficient inspection processes.
Data Source
AI summary
A display device including: a display panel; a first substrate attached to a side of the display panel; and a second substrate attached to a side of the first substrate, wherein the display panel includes a first panel test pad and a second panel test pad, the first substrate includes a 1-1 circuit test lead overlapping and connected to the first panel test pad, a 1-2 circuit test lead overlapping and connected to the second panel test pad, a 2-1 circuit test lead overlapping and connected to the second substrate, a 1-1 test lead line connected to the 1-1 circuit test lead, a 1-2 test lead line connected to the 1-2 circuit test lead, and a first test lead line connected to the 2-1 circuit test lead, and the 1-1 test lead line and the 1-2 test lead line are connected to the first test lead line.