Linear exposure control system
US4113378A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 2, 1977 |
| Grant date | Sep 12, 1978 |
| Priority date | — |
| Expiry date | Mar 2, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B27/722
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A magnification signal of 64 - 100% is applied as an input parameter to a specially designed relaxation oscillator which produces a pulse train wherein the pulses thereof have a duration which vary in linear fashion with respect to the magnification input signal, the relaxation oscillator employing a constant current source in series relationship with an integrating capacitor which produces a saw tooth signal having a slope which is constant regardless of variations in the amplitude of the magnification input signal. The output pulses from the relaxation oscillator are counted to define an exposure control interval which changes linearly with respect to the input magnification signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.