Cathode and Anode Pad Placement for Display Inspection
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Solution Overview
Problem
In the manufacturing of display devices using multi-piece substrates, the narrowing peripheral region limits the space for test pads, leading to inaccurate inspections and potential heat generation issues due to long wiring or thinned wiring at cutting lines, especially in organic electroluminescence display devices.
Innovation Solution
The method involves disposing cathode and anode pads within the product regions for inspecting light-emitting elements, while second test pads in the blank regions focus on power supply and control signals, allowing efficient use of space and reducing wiring length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If test pads are disposed in the peripheral region outside the product region, then inspection can be performed, but the wiring becomes long causing voltage drop and heat generation
Solution Approach 1:
The patent changes the spatial arrangement by disposing cathode and anode pads within the product region itself rather than in the peripheral region. This dimensional repositioning allows the current path to be shortened significantly, reducing voltage drop and heat generation while maintaining inspection functionality.
Solution Approach 2:
The patent applies different functional qualities to different regions: the cathode and anode pads are specifically positioned within the product region to minimize wiring length for current supply, while other test pads can be located in the peripheral region. This local optimization ensures that the critical current path is as short as possible.
2Measurement precision
If test pads are disposed in the peripheral region outside the product region, then inspection can be performed, but the wiring may be thinned at cutting line portions
Solution Approach 1:
By repositioning the cathode and anode pads within the product region, the wiring path is completely redesigned to avoid the cutting line portions. This eliminates the need to thin the wiring at cutting lines, maintaining full wiring integrity and reliability.
Solution Approach 2:
The critical current-supplying pads (cathode and anode) are extracted from the peripheral region and placed within the product region, separating their function from the other test pads. This extraction allows the current path to be optimized independently from the cutting line requirements.
3Area of stationary object
If the peripheral region is narrowed to enlarge the display area, then the display area is increased, but there is no space to dispose test pads in the peripheral region
Solution Approach 1:
The patent resolves the space constraint by moving the critical test pads (cathode and anode) from the peripheral region into the product region. This repositioning allows the peripheral region to be narrowed for larger display area while still providing space for other test pads, and ensures current supply pads are optimally positioned.
Solution Approach 2:
The product region serves multiple functions: it contains the display elements and also accommodates the cathode and anode pads for inspection. This multi-functionality allows efficient use of the limited space while maintaining both display area and inspection capabilities.
4Ease of manufacture
If wiring is thinned at cutting line portions to enable easy cutting, then cutting is facilitated, but accurate inspection cannot be performed due to voltage drop
Solution Approach 1:
The current-supplying pads are extracted from the peripheral region and placed within the product region, creating a separate optimized current path that does not intersect with cutting lines. This allows cutting lines to be positioned without affecting the current path, enabling both easy cutting and accurate inspection.
Solution Approach 2:
The patent segments the pad functions: cathode and anode pads are positioned within the product region for current supply, while other test pads remain in the peripheral region. This segmentation allows the current path to be optimized separately from the cutting line locations.
Data Source
AI summary
A multi-piece substrate integrally having a plurality of product regions each provided with a light-emitting element driven by a current and a blank region adjacent to each of the plurality of product regions is prepared. The current is passed through a cathode pad and an anode pad to inspect the light-emitting element. A plurality of display panels are cut out from the multi-piece substrate so as to respectively correspond to the plurality of product regions. The multi-piece substrate includes a plurality of first test pads disposed in each of the plurality of product regions for inspecting the light-emitting element, and a plurality of second test pads disposed in the blank region for inspecting the light-emitting element. The cathode pad and the anode pad are included in the plurality of first test pads and are not included in the plurality of second test pads.