Speed control device for a sewing machine
US4172989A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 3, 1977 |
| Grant date | Oct 30, 1979 |
| Priority date | — |
| Expiry date | Jun 3, 1997 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S388/919
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A speed control device for a sewing machine includes at least means for providing a speed reference voltage signal, means for producing a motor speed voltage signal responsive to an actual speed of the driving motor, and means for comparing the speed reference voltage signal with the motor speed voltage signal to provide a speed difference signal. The speed difference signal is utilized to determine triggering angle of a thyristor means for controlling the motor speed and to maintain the predetermined motor speed irrespective of any variation in the driving torque of the motor, the voltage of the power source and the frequency of the A.C. power source.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.