Photometer for use in a camera
AssigneeRicoh Company, Ltd.
InventorsTouru Sakaguchi, Akira Takahashi, Akira Ueno
Life of this patent
Estimating the term…
Abstract
A photometer in a camera having a plurality of light receiving portions on an identical substrate for conducting photo-metering for portions each corresponding to a marginal area and a central area of a picture plane in the camera.
Claims4
A photometer in a camera having a plurality of light receiving portions on an identical substrate for conducting photo-metering for portions each corresponding to a marginal area and a central area of a picture plane in the camera, comprising:
- a first light receiving portion comprising a narrow zigzag stripe-like photoconductive material disposed to cover most of a marginal portion of the substrate corresponding to the marginal area of the picture plane;
- a first electrode in contact with an outer circumference of the first light receiving portion;
- a second light receiving portion comprising a narrow zigzag stripe-like photoconductive material about as a central portion of the substrate corresponding to the central area of the picture plane;
- a second electrode in contact with an outer circumference of the second light receiving portion and in contact with an inner circumference of the first light receiving portion;
- a third electrode in contact with an inner circumference of the second light receiving portion;
- and
- switching means for making a short-circuit between the second and first electrodes when a voltage is applied between the first and third electrodes, wherein a signal indicative of brightness of an object is produced from the third electrode if the short-circuit is made by the switching means, and a back-light signal indicative of extent of back-light of the object is produced from the second electrode if the short-circuit is not made by the switching means.
A photometer in a camera having a plurality of light receiving portions on an identical substrate for conducting photo-metering for portions each corresponding to a marginal area and a central area of a picture plane in the camera, comprising:
- a first light receiving portion comprising a narrow stripe-like photoconductive material disposed to cover most of a marginal portion of the substrate corresponding to the marginal area of the picture plane;
- a first electrode in contact with an outer circumference of the first light receiving portion;
- a second light receiving portion comprising a narrow stripe-like receiving portion and about at a central portion of the substrate corresponding to the central area of the picture plane;
- a second electrode in contact with an outer circumference of the second light receiving portion and in contact with an inner circumference of the first light receiving portion;
- a third electrode in contact with an inner circumference of the second light receiving portion;
- a power source for applying a reference voltage between the first and third electrodes;
- switching means for making a short-circuit between the second and first electrodes, wherein a signal indicative of brightness of an object is produced from the third electrode if the short-circuit is made by the switching means, and a back-light signal indicative of extent of back-light of the object is produced from the second electrode if the short-circuit is not made by the switching means;
- a brightness difference calculating means for calculating a brightness difference between the marginal portion and the central portion of the substrate on the basis of the back-light signal produced from the second electrode;
- and
- a compensating signal producing means for producing a compensating signal on the basis of the brightness difference calculated by the brightness difference calculating means, said compensating signal being added to the signal indicative of brightness of the object produced from the third electrode.
Dependencies are inferred from the claim text.