Light quantity control device
US4417179A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 7, 1982 |
| Grant date | Nov 22, 1983 |
| Priority date | — |
| Expiry date | May 7, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B41/3922
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A light quantity control device for controlling the quantity of light emitted from a light source supplied with a.c. power through a bidirectional switching element is disclosed which comprises an integrating circuit for integrating an electric signal corresponding to the quantity of emitted light to produce a light quantity signal varying in accordance with a change in quantity of emitted light and another integrating circuit for integrating the light quantity signal with a predetermined period to produce an exponentially rising signal for every predetermined period, and in which the output of the latter integrating circuit is compared with a reference value to obtain a control signal having a duration time corresponding to the results of comparison, and the switching element is controlled by the control signal to perform a phase control for the a.c. power.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.