Trimmed Corner Optical Sheets for Backlight Detection
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Solution Overview
Problem
Conventional illumination apparatuses for liquid crystal display devices face challenges in detecting inverted optical sheets and maintaining a compact size without reducing the active area, as they rely on protruding ear portions that increase the apparatus' size.
Innovation Solution
The design incorporates optical sheets with trimmed corner portions that correspond to the housing's surface, allowing for easy detection of upside-down orientation and missing sheets, while maintaining a small size by using a housing with a wall portion that surrounds the sheets and opposing surfaces to guide the trimmed tips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If ear portions protrude from optical sheets to detect inverted placement, then detection of inverted orientation is improved, but the housing size and overall apparatus size increase
Solution Approach 1:
The patent applies asymmetry by trimming only specific corner portions of the optical sheets rather than adding protruding elements. Each optical sheet has asymmetric corner trimming patterns (e.g., first corner trimmed by line segment L1, second corner by L2, third corner by L3) that create unique positional relationships. When sheets are stacked in correct order, the trimmed corners align with corresponding opposing surfaces in the housing. If sheets are inverted or misplaced, the asymmetric trimming patterns cause visible misalignment, enabling detection without increasing housing volume.
2Difficulty of detecting and measuring
If ear portions protrude from optical sheets to detect inverted placement, then detection of inverted orientation is improved, but the active area of optical sheets decreases
Solution Approach 1:
The asymmetric corner trimming removes minimal material from each sheet while creating sufficient geometric variation for detection. The trimming line segments (L1, L2, L3, L4) are designed to be just enough to create detectable positional differences when sheets are stacked, preserving maximum active area. This contrasts with protruding ear portions that would require significant material addition or separate detection components.
3Volume of stationary object
If optical sheets are laminated without detection features, then the apparatus size is reduced, but the ability to detect inverted placement is lost
Solution Approach 1:
The patent implements preliminary action by pre-trimming the corner portions of optical sheets during manufacturing with specific asymmetric patterns. These trimming features are built into the sheets before assembly, so that when sheets are stacked in the housing, the trimmed corners automatically align with corresponding opposing surfaces. This pre-configured geometric feature enables automatic visual detection of inverted or misplaced sheets without requiring additional detection mechanisms or increasing apparatus complexity.
Data Source
AI summary
In a backlight apparatus, laminated optical sheets are housed in a tray such that a wall portion thereof surrounds their circumferences so that the optical sheets receive light from fluorescent lights. Tips of one corner portion A of optical sheets preferably have a shape in which the tips are trimmed by line segments extending between two edges defining the corner portions. At the wall portion of the tray, an opposing surface is formed along the line segments of the corner portions so as to correspond to the shape of the corner portions having tips trimmed off. The opposing surface restrains the line segments.