Exposure amount control device for a copying machine
US4527093A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 27, 1983 |
| Grant date | Jul 2, 1985 |
| Priority date | — |
| Expiry date | Oct 27, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B27/72
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Disclosed is an exposure amount control device for a copying machine comprising an exposure amount control circuit for controlling an exposure amount by controlling light of the exposure lamp for illuminating an original document to be copied and a digital light control signal generator for supplying a digital light control signal of a variable duty factor to the exposure amount control circuit. The digital light control signal generator includes a light intensity increase/decrease setting circuit and an oscillator for generating an oscillation output of a variable oscillation period in accordance with a light intensity signal from the light intensity increase/decrease setting circuit. The oscillation output of the oscillator is converted to an on-off light signal, which is supplied to the exposure amount control circuit as the digital light control signal. Thus, the digital light control signal generator is perfectly electrically isolated from a primary power supply circuit of the exposure amount control circuit and a highly safe exposure amount control device with a stable control ability due to an on-off light signal is provided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.