Electronic rheostat method and apparatus
US4935641A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 2, 1988 |
| Grant date | Jun 19, 1990 |
| Priority date | — |
| Expiry date | Aug 2, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02B20/00
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An electronic reostat circuit having a pulse width modulated output for controlling energization of a device such as a vehicle dashboard illumination lamp. A comparator circuit compares a reference signal adjusted by a user with an alternating signal, preferably a saw tooth waveform, and generates a pulse width modulated output whose duty cycle varies directly with the size of the reference signal. The reference signal is generated by a tapped resistor array wherein contacts on the array are coupled to ground by a rotary switch contact which can be adjusted by the user. By raising and lowering the reference signal, the duty cycle can be changed from a minimum to maximum and thereby produce a minimum and maximum lamp illumination signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.