Sewing machine bobbin thread run-out alarm using reflected light
US4163158A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 25, 1978 |
| Grant date | Jul 31, 1979 |
| Priority date | — |
| Expiry date | Apr 25, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V8/16
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A mechanism for detecting the depletion of bobbin thread in a sewing machine. A bobbin is formed with a polygonal core having a plurality of light reflecting surfaces contained thereon. A light source transmits a beam of light toward the polygonal core of the bobbin and the light reflected therefrom is intercepted by a photodetector. The polygonal reflecting surfaces contained on the bobbin core do not begin to reflect light until a sufficient quantity of bobbin thread has been consumed in the sewing process to expose a part of the reflective surface portion of the bobbin core. The rotation of the bobbin thereafter results in flashes of light being received by the photodetector. An electronic circuit analyzes the output of the photodetector and distinguishes between the flashes and steady ambient light to signal the impending depletion of bobbin thread.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.