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US3821768A Expired / Lapsed US ⏱️ 0.0 years remaining

Viewfinder shield in a single lens reflex camera adopting a ttl lightmeasuring method

Assignee: Asahi Chemical Co Ltd
•
Filing: 1972-08-09
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Granted: 1974-06-28
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Expires: 1992-08-09
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Abstract

Abstract A LIGHT-BLOCKING PLATE RELEASED BY A SHUTTER BUTTON IS INSERTED IN THE FINDER LIGHT PATH WITHIN A SINGLE LENS REFLEX CAME RA INLCUDING AN ELECTRIC SHUTTER DEVICE OF TTL LIGHT MEASURING TYPE FOR BLOCKING ONLY THE INVERSE INCIDENT LIGHT COMING THROUGH THE FINDER EYEPIECE. A LIGHT MEASUREMENT IS COMPLETED AFTER TERMINATION OF BLOCKING MOVEMENT OF THE LIGHT-BLOCKING PLATE AND DURING THE TIME PERIOD OF SUCH ASSOCIATING MOVEMENTS AS TEH SWINGING-UP MOVEMENT OF THE REFLECTING MIRROR AND THE DIAPHRAGM VALUE ADJUSTING OPERATION. AFTER COMPLETING THE SHUTTER CLOSING OPERATION THE LIGHTBLOCKING PLATE IS RETRACTED OUT OF THE FINDER LIGHT PATH BY MEANS OF A MECHANICAL LEVER AND SPRING ARRANGEMENT.

Inventors

  • 👤 F Urano
  • 👤 N Uno
  • 👤 T Sakazaki
  • 👤 K Miyata
  • 👤 K Nomura
  • 👤 K Watanabe

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-27 08:35
CPC Classifications
G; G03; G03B; G03B19/00; G03B19/02; G03B19/12

Claims Analysis

Total Claims: 0
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References Cited (Backward Citations)

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USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1977-06-27 1977-12-27 1978-06-28 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1981-06-27 1981-12-27 1982-06-28 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1985-06-27 1985-12-27 1986-06-28 $7700.00 Window Closed / Lapsed

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