公开(公告)号：US3698301A

公开(公告)日：1972-10-17

申请号：US3698301D

申请日：1969-07-18

Applicant: PENTACON DRESDEN VEB

Inventor： REIMANN HUBERTUS ,  LINDNER FRITZ

IPC: G01J1/44 ,  G03B17/20 ,  G01J1/10

CPC classification number: G01J1/44 ,  G03B17/20

Abstract: An exposure measuring apparatus has a lighting element which can be connected to and influenced by a source of supply potential. Means are provided for presetting the light emission of the lighting element. A photo-sensitive receiver influenced by prevailing light conditions is connectable with the source of supply potential and influences the light emission of a second lighting element which is connected in circuit with the photosensitive receiver and at least one resistance attenuation element. The resistance attenuation element or elements are adapted to adjust the light emission of the second lighting element in accordance with required exposure factors when the supply potential is connected. The lighting elements are formed as light source pillars the color of which are influenced by their supply frequency, e.g. electro luminescent plates. The source of supply potential is an alternating current source and the second lighting element is connected therewith via a variable frequency generator the frequency of which is influenced by the setting of the resistance attenuation elements. The first and second lighting elements are arranged to illuminate respective surfaces positioned immediately adjacent one another whereby when the color and brightness of each of the surfaces is equal, the exposure factors are set to values required for accurate exposure.