Patent · US Expired

Automatic diaphragm assembly

US4113359A · kind A · utility

24Cited by
4References
15Claims
0Family size

Inventors

Key dates

Filing dateMar 16, 1977
Grant dateSep 12, 1978
Priority date—
Expiry dateMar 16, 1997

Classification

  • Technology area (CPC G)Physics
  • CPC primaryG03B9/06
  • WIPO fieldOptics
  • WIPO sectorInstruments

Abstract

An automatic diaphragm assembly for use in an optical or optoelectronic image pick-up device having lens systems, comprising diaphragm blades forming a variable aperture, at least one neutral-density filter element movable with one of the diaphragm blades, and an electromagnetic drive unit including a ring-shaped permanent magnet having locally magnetized pole portions alternately disposed circumferentially of the magnet and a ferromagnetic ring forming a circular air gap between the permanent magnet and the ferromagnetic ring.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.