Flattened External Electrodes for EEFL Contact Reliability
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Solution Overview
Problem
The existing external-electrode fluorescent lamps (EEFLs) experience unsatisfactory electrical contact due to the cylindrical shape of their electrodes and the corresponding curved sections of the conductive strips, leading to inefficient power supply in back-lighting panels for transmissive or transflective liquid-crystal displays.
Innovation Solution
The EEFLs are designed with extended portions of external electrodes that are flattened to form two substantially flat circumferential areas, allowing for improved electrical contact with conductive strips, which have curved sections that fit snugly around these areas, ensuring a tight and secure connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the external electrode is made cylindrical to match the fluorescent tube shape, then the manufacturing simplicity and structural integrity are improved, but the electrical contact with the conductive strip deteriorates
Solution Approach 1:
The external electrode is designed with different geometries at different locations: the main body remains cylindrical to maintain structural integrity and ease of manufacture, while the extended portion is flattened to create flat circumferential areas that provide improved electrical contact with the conductive strip. This local modification resolves the contradiction by applying different geometric qualities to different parts of the same component.
Solution Approach 2:
The external electrode is divided into two distinct portions: a cylindrical main body portion that maintains the traditional shape for ease of manufacture, and a flattened extended portion that provides improved electrical contact. This segmentation allows each portion to optimize its geometry for its specific function, resolving the contradiction between manufacturing simplicity and electrical contact reliability.
2Ease of operation
If the conductive strip has curved sections to fit the cylindrical electrode, then the ease of mounting is improved, but the electrical contact quality deteriorates due to point contact
Solution Approach 1:
The conductive strip is designed with curved sections that locally adapt to the flattened extended portion of the external electrode. The curved sections have sidewalls that contact the flat circumferential areas, transforming the point contact into line or surface contact. This local geometric adaptation resolves the contradiction by providing both ease of mounting through the curved fit and improved electrical contact through increased contact area.
3Reliability
If the curved section width is made slightly smaller than the extended portion width, then the tight fit and electrical contact are improved, but the manufacturing precision requirement increases
Solution Approach 1:
The curved section of the conductive strip is designed with a width slightly smaller than the extended portion of the external electrode, creating an interference fit. This deliberate dimensional mismatch generates elastic deformation and contact pressure that ensures reliable electrical contact. The design anticipates and compensates for the precision requirement by using the elastic properties of the materials to accommodate minor dimensional variations, thus resolving the contradiction between contact reliability and manufacturing precision.
Data Source
AI summary
An external-electrode fluorescent lamp has two external electrodes disposed on its ends, wherein each external electrode has an extended portion flattened to form two substantially flat circumferential areas. With such flattened circumferential areas, the electric contact made to the conductive strip can be improved. For mounting a row of external-electrode fluorescent lamps, a mounting base with two electrically conductive strips are used. Each electrically conductive strip has a plurality of curved sections to fit the extended portion of the external electrode. The curved section has two substantially sidewalls to make contact with the flat circumferential areas of the extended portion of the external electrode. The extended portion can also be slightly tapered.