1986-09-16
1988-10-18
Perkey, W. B.
354477, G03B 7099
Patent
active
047791160
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention concerns an exposure measuring element and an exposure device having such an element.
From Swiss Pat. No. 440,747 an exposure-measuring device is known which has a bar-shaped housing, one end portion of which is provided with front and rear window openings and with a photoelectric transducer which is movable into active position in front of the rear window opening while its other end portion is arranged for manipulating the device. The device can have means for swinging itself into the surface of a frosted glass plate.
Upon use, the end portion of the housing having the window openings is brought directly in front of or behind the frosted glass plate.
In the case of measurement in front of the frosted glass plate, the plane of the frosted glass plate is defocused as in the case of the known measurement cassette, so that refocusing is necessary upon each measurement. In the case of measurement behind the frosted glass plate, the measurement, which is dependent on the scattering angle of the frosted glass plate, is falsified.
The present invention is directed at remedying this. The invention, as characterized in the claims, solves the problem of creating an exposure-measuring device in which the measurement of the light takes place in the film plane and in which the handling of separate devices is unnecessary.
The advantages which can be obtained by the invention reside in the fact that a selective point-measurement or a differentiated integral measurement can be effected in the film plane, that a selective multi-point measurement can be carried out instead of a wide-field measurement, and that the average brightness range of the photograph can result from a single measurement.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages will become evident from the following description of one embodiment of the invention, with reference to the accompanying drawing, in which:
FIG. 1 is a front view of an exposure-measuring element;
FIG. 2 shows, on a larger scale, a detail of the area of the device shown in FIG. 1 enclosed by a circle II, but with a photoelectric transducer removed; and
FIG. 3 is a section along the line III--III of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows an exposure measuring element which contains a known frosted glass plate 1, four photoelectric transducers 2 and a conductor arrangement. Transducers 2 are each localized in shape, as opposed to elongated. The conductor arrangement comprises contact elements 3 which are formed near the edge of one narrow side of the frosted glass plate. Connection regions 4 and 5, shown in FIGS. 2 and 3, are provided for the photoelectric transducers. Conductive paths 6 and 7 connect the connection regions 4 and 5 to the corresponding contact elements 3. The conductor arrangement consists of electrically conductive layers which are applied to the frosted side of glass plate 1.
As shown in FIG. 2, the connection regions 4, 5 for the photoelectric transducers 2 are of different dimensions. The connection regions 4, which has the larger surface, is developed as a contact surface on which a photoelectric transducer 2 is so fastened that it is connected in electrically conductive manner to it. A bond wire 8 is welded at one end to transducer 2, and at another end to the other connecting region 5 beneath. As indicated in FIG. 1, the contact surfaces 4 the individual photoelectric transducers 2 (see FIG. 3) 2 are together connected by conductive paths 6 to one contact element 3 while the connection regions 5 of smaller area are connected individually via separate conductive paths 7 to respective elements 3. Formation of the connecting regions 4, 5 and of the conductive paths 6, 7 is known. The connecting regions 4, 5 and the conductive paths 6, 7 for instance could consist of a first layer of copper, a second layer of nickel and a third layer of bonded gold without brightener.
The exposure measuring element can be inserted into a camera, with the contact elements 3 engagi
REFERENCES:
patent: 856618 (1907-06-01), Brownell
patent: 3471704 (1969-10-01), Koch
patent: 3620147 (1971-11-01), Ataka et al.
patent: 4047187 (1977-09-01), Mashimo et al.
patent: 4104651 (1978-08-01), Matsumoto et al.
patent: 4130355 (1978-12-01), Ohtaki et al.
L. Andrew Mannbeim, "Look What's Happening to Large-Format Cameras!", Canadian Photography, June 1979, pp. 27 and 29-32.
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