Camera

• US 5,257,056 A
• Filed: 07/30/1992
• Issued: 10/26/1993
• Est. Priority Date: 08/02/1991
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kazumi, Jiro
• Primary Examiner(s): Gellner, Michael L.
• Assistant Examiner(s): BLANKENSHIP, HOWARD BENNETT
• Application Number:
  US07/921,762
• Time in Patent Office: 453 Days
• Field of Search: 354/146, 354/226, 354/227.1, 354/234.1, 354/235.1, 354/237, 354/238.1, 354/241, 354/242, 354/243, 354/245, 354/246
• US Class Current: 396/263
• CPC Class Codes: G03B 17/20 visible in viewfinder
• CPC Class Codes: G03B 9/18 More than two members
• CPC Class Codes: G03B 9/34 with adjustable slot; with mechanism controlling relative movement of blinds to form slot

Abstract

A camera having a shutter device including leading and trailing curtains includes a first switch arranged to detect the ready-to-travel state and the travel-completed state of the leading curtain, a second switch arranged to detect the ready-to-travel state and the travel-completed state of the trailing curtain, and a decision circuit arranged to determine that the shutter device is abnormal, either when the ready-to-travel state of the leading curtain is not detected by the first switch or when that of the trailing curtain is not detected by the second switch, before an operation of the shutter device. The decision circuit also determines that the shutter device is abnormal, after completion of control over the travels of the leading and trailing curtains by the shutter device, if the travel-completed state of the leading curtain is not detected by the first switch within a predetermined period of time after the travel-completed state of the trailing curtain is detected by the second switch.

Claims

1. A camera having a shutter device including a leading curtain and a trailing curtain, comprising:

a) first switch means for detecting a ready-to-travel state and a travel-completed state of said leading curtain;

b) second switch means for detecting a ready-to-travel state and a travel-completed state of said trailing curtain; and

c) decision means arranged to determine before an operation of said shutter device that said shutter device is abnormal, when at least one of the ready-to-travel state of said leading curtain is not detected by said first switch means and the ready-to-travel state of said trailing curtain is not detected by said second switch means, and said decision means determining that said shutter device is abnormal after completion of control over the traveling states of said leading and trailing curtains by said shutter device, when the travel-completed state of said leading curtain is not detected by said first switch means within a predetermined period of time after the travel-completed state of said trailing curtain is detected by said second switch means.

2. A camera according to claim 1, further comprising indicating means for indicating a determination by said decision means that the shutter device is abnormal.

3. A camera according to claim 2, wherein said indicating means includes an optical display.

4. A camera according to claim 2, wherein said indicating means is arranged to indicate the abnormality of said shutter device by stopping a motion of a camera acting member.

5. A camera according to claim 1, wherein said decision means is arranged to determine that said shutter device is abnormal when the travel-completed state of said leading curtain is not detected by said first switch means within a period of time that allows shutter curtain chattering to dissipate, after the travel-completed state of said trailing curtain is detected by said second switch means.

6. A camera according to claim 1, wherein said decision means is arranged to accept a result of detection made by said first switch means after completion of control by said shutter device over the traveling states of said leading and trailing curtains, only in a case where a set shutter speed of the camera is lower than a predetermined shutter speed value.