Auto exposure control device for reader-printer
US4591264A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 29, 1985 |
| Grant date | May 27, 1986 |
| Priority date | — |
| Expiry date | Jan 29, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B27/72
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
There is disclosed an automatic exposure control device for use in a reader-printer which controls the amount of exposure in accordance with outputs of photodetectors arranged in an optical path. Each photodetector is connected to a comparator which is supplied with comparison voltage through changes of the comparison voltage stepwise. The control device changes the amount of variation per step of comparison voltage in accordance with a change of the type of film to the positive or to the negative, and limits the photodetectors to be used for controlling only to the photodetectors being capable of receiving the light of micro film image.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.