US3704947A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Micro-film camera
Assignee: Pentacon GmbH Foto und Feinwerktechnik
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Filing: 1971-01-04
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Granted: 1972-12-05
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Expires: 1991-01-04
Abstract
Abstract A microfilm camera for reproducing documents is provided with a photo receiver mounted on its housing. An optical system mounted on the housing directs light reflected by a punctiform area near the edge of the document to be photographed onto the photo receiver. A wedge prism is rotatably mounted on the housing in the light path between the photo receiver and the document to enable the puntiform portion scanned by the photo-receiver to be varied over the document and its border during a rotation of the wedge prism. Mounted on the housing is a drive means which rotates the wedge at a constant speed. Provision is made for reducing the output from the photo-electric device to a zero illumination level once during each revolution of the wedge prism. Mounted on the housing is a measuring circuit which includes a rectifier connected with an output of the photoreceiver and a storage device having a time constant long compared with the time for one rotation of the wedge prism and effective to store a voltage indicative of the brightness of the document. A control device is influenced by the output of the storage device provides a controlled voltage which influences the illumination of the lamp in dependence on the brightness of the document border.
Inventors
- 👤 Hubertus Reimann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 13:37
CPC Classifications
G; G03; G03B; G03B27/00; G03B27/72; G03B27/80
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
221 words
In a microfilm camera for reproducing documents the provision or a photo-receiver mounted on the camera housing, an optical system mounted on the camera housing for directing light reflected by a punctiform area near to the edge of the document to be photographed onto the photo-receiver, a wedge prism rotatably mounted on the housing in the light path between the photo-receiver and the document to enable different punctiform portions of the document and its border to be scanned by the photo-receiver during a rotation of the wedge prism, drive means mounted on the housing for rotating the wedge at constant speed, means for reducing the output of the photo-electric device to a zero illumination level once during each revolution of the wedge prism, a measuring circuit mounted on the camera housing including a rectifier circuit connected with an output of the photo-receiver and a storage deVice having a time constant long compared with the time for one rotation of the wedge prism effective to store a voltage indicative of the brightness of the document, a control device having an input connected with the output of the storage device and an output connected with a lamp arranged to illuminate the document whereby the illumination of the document in controlled by the control device in dependence on the brightness of the document border.
Claim 2
Dependent Claim
221 words
In a microfilm camera for reproducing documents the provision or a photo-receiver mounted on the camera housing, an optical system mounted on the camera housing for directing light reflected by a punctiform area near to the edge of the document to be photographed onto the photo-receiver, a wedge prism rotatably mounted on the housing in the light path between the photo-receiver and the document to enable different punctiform portions of the document and its border to be scanned by the photo-receiver during a rotation of the wedge prism, drive means mounted on the housing for rotating the wedge at constant speed, means for reducing the output of the photo-electric device to a zero illumination level once during each revolution of the wedge prism, a measuring circuit mounted on the camera housing including a rectifier circuit connected with an output of the photo-receiver and a storage deVice having a time constant long compared with the time for one rotation of the wedge prism effective to store a voltage indicative of the brightness of the document, a control device having an input connected with the output of the storage device and an output connected with a lamp arranged to illuminate the document whereby the illumination of the document in controlled by the control device in dependence on the brightness of the document border.
Claim 3
Dependent Claim
52 words
A microfilm camera according to claim 1 wherein the means for reducing the output of the photo-electric device to zero illumination level comprises a switch adapted to short circuit the photo-electric device and a switch cam mounted on the housing and driven by the drive means to effect closure of the switch.
Claim 4
Dependent Claim
46 words
A microfilm camera according to claim 1 wherein the reduction of the output of the photo-electric device to zero illumination level is effected by the wedge prism which is adapted so that the variable portion scanned overlaps the edge of the document whereby no reflection occurs.
Claim 5
Dependent Claim
217 words
In a microfilm camera for reproducing documents of the type having a sector diaphragm driven by a drive means and effective to block light passage to a photo-receiver during each exposure, the provision of an optical system mounted on the camera housing for directing light reflected by a punctiform area near to the edge of the document to be photographed onto the photo-receiver, a wedge prism rotatably mounted on the housing and coupled to the drive means, which prism is positioned in the light path between the photo-receiver and the document to enable different punctiform portions of the document and its border to be scanned by the photo-receiver during a rotation of the wedge prism by the drive means, a measuring circuit mounted on the camera housing including a rectifier circuit connected with an output of the photo-receiver and a storage device having a time constant long compared with the time for one rotation of the wedge prism effective to store a voltage indicative of the brightness of the document, a control device having an input connected with the output of the storage device and an output connected with a lamp arranged to illuminate the document whereby the illumination of the document is controlled by the control device in dependence on the brightness of the document border.
Claim 6
Dependent Claim
217 words
In a microfilm camera for reproducing documents of the type having a sector diaphragm driven by a drive means and effective to block light passage to a photo-receiver during each exposure, the provision of an optical system mounted on the camera housing for directing light reflected by a punctiform area near to the edge of the document to be photographed onto the photo-receiver, a wedge prism rotatably mounted on the housing and coupled to the drive means, which prism is positioned in the light path between the photo-receiver and the document to enable different punctiform portions of the document and its border to be scanned by the photo-receiver during a rotation of the wedge prism by the drive means, a measuring circuit mounted on the camera housing including a rectifier circuit connected with an output of the photo-receiver and a storage device having a time constant long compared with the time for one rotation of the wedge prism effective to store a voltage indicative of the brightness of the document, a control device having an input connected with the output of the storage device and an output connected with a lamp arranged to illuminate the document whereby the illumination of the document is controlled by the control device in dependence on the brightness of the document border.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-12-05 | 1976-06-05 | 1976-12-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-05 | 1980-06-05 | 1980-12-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-05 | 1984-06-05 | 1984-12-05 | $7700.00 | Window Closed / Lapsed |