Cylindrical Lens Asymmetry for Weft Yarn Detection
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Solution Overview
Problem
Existing weft-yarn detection apparatuses in looms face detection failures due to the narrow detection range caused by high curvature lenses, which either exclude part of the weft yarn path or include warp yarns and cut-off selvages, leading to insecure detection of weft yarn arrival.
Innovation Solution
A weft-yarn detection apparatus using a cylindrical lens with a convex surface curvature greater in the weft-inserting direction than in the short-length direction of the reed, ensuring a wider detection range vertically and narrower range horizontally to exclude warp yarns and cut-off selvages, thereby securely detecting the weft yarn.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the curvature of the plano-convex spherical lens is set small to include the whole path in the reed, then the detection range includes the whole path vertically, but the detection range also includes warp yarns and cut-off selvages causing detection failure
Solution Approach 1:
The patent applies asymmetry by using a cylindrical lens instead of a spherical lens, creating different curvature radii in different directions. Specifically, the curvature radius in the weft-inserting direction (first direction) is smaller than the curvature radius in the direction perpendicular to the weft-inserting direction (second direction). This asymmetric design allows the detection range to be narrow in the horizontal direction (excluding warp yarns and selvages) while being wide in the vertical direction (including the whole path in the reed), thereby resolving the contradiction between detection range and detection accuracy
Solution Approach 2:
The patent applies local quality by making different regions of the lens have different optical properties. The cylindrical lens has a smaller curvature radius in the weft-inserting direction to narrow the detection range horizontally and exclude interfering elements, while having a larger curvature radius in the perpendicular direction to widen the detection range vertically and include the entire path. This directional differentiation of optical properties allows simultaneous achievement of both narrow and wide detection ranges in different directions
2Reliability
If the curvature of the lens is set great to reduce detection failure of weft yarn, then the detection range is narrowed, but the detection range may exclude part of the path formed in the reed
Solution Approach 1:
The patent resolves this contradiction by implementing asymmetric curvature in the cylindrical lens. The lens has a smaller curvature radius in the weft-inserting direction (first direction) which narrows the detection range horizontally to exclude warp yarns and selvages, improving detection accuracy. Simultaneously, the lens has a larger curvature radius in the direction perpendicular to the weft-inserting direction (second direction) which widens the detection range vertically to include the whole path in the reed, preventing exclusion of the detection target
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
The apparatus effectively reduces detection failures by ensuring the whole weft yarn path is included while excluding warp yarns and cut-off selvages, enhancing the reliability of weft yarn detection with increased light reception and signal strength.
Implementation Method 1
If the weft-yarn detection apparatus is a reflection type, the light-receiving element may receive the light reflected off some of the warp yarns and the cut-off selvages
Implementation Method 2
the light emitted from the light-emitting element converges through the lens identically in both the horizontal and vertical directions
Implementation Method 3
the projected light is received by the light-receiving element. When a leading end of the weft yarn traveling through the path formed in the reed passes through a detection position (a light-projected position) of the weft-yarn detection apparatus, an amount of the light received by the light-receiving element changes
Data Source
Figure 1
Figure 2
AI summary
A weft-yarn detection apparatus (11) of a loom for detecting an arrival of a weft yarn inserted includes a lens (23) disposed to face the weft yarn inserted along a weft-inserting direction (Y), a light-emitting element (21) emitting light to be projected on the weft yarn through the lens (23), and a light-receiving element (22) receiving the light emitted from the light-emitting element (21). The lens (23) is a cylindrical lens. A lens surface (25) of the lens (23) on a side facing the weft yarn is a convex surface and has a curvature that is greater in the weft-inserting direction (Y) than in a short-length direction (Z) of a reed (12).