Shutter control device for a camera having a shutter release lock device

• US 4,362,373 A
• Filed: 04/10/1981
• Issued: 12/07/1982
• Est. Priority Date: 04/30/1980
• Status: Expired due to Term

• Current Assignee: Nikon Corporation
• Original Assignee: Nippon Kotsu Kabushiki Kaisha (Nikon Corporation)
• Inventors: Kazami, Kazuyuki, Ohtsubo, Yoshiaki
• Primary Examiner(s): ADAMS JR, RUSSELL E
• Application Number:
  US06/252,995
• Time in Patent Office: 606 Days
• Field of Search: 354/60 R, 354/60 L, 354/234, 354/242, 354/267, 354/289
• US Class Current: 396/221
• CPC Class Codes: G03B 7/0807 Control circuits G03B7/10 takes precedence
• CPC Class Codes: G03B 7/083 for control of exposure time
• CPC Class Codes: G03B 7/087 for control of both exposure time and aperture
• CPC Class Codes: G03B 9/08 Shutters

Abstract

A shutter control device for a camera having an automatic exposure time control device provided with a comparator circuit for comparing a time output corresponding to the lapse of time from the opening operation of a shutter with a proper shutter speed output representing a proper shutter speed and for generating a comparison output when the two outputs are in a predetermined relation and a magnet for blocking the closing operation of the shutter by energization, the magnet being adapted to be deenergized in response to the comparison output to close the shutter, and a shutter release lock device provided with voltage detecting means for detecting a power source voltage and for deenergizing and magnet before the opening operation of the shutter when the power source voltage is below a reference value and blocking means for blocking the opening operation of the shutter by the deenergization of the magnet before the opening operation of the shutter includes means for forcibly energizing the magnet until the start of the opening operation of the shutter in response to shutter release operation. The means for forcibly energizing the magnet becomes operative in response to the output of the voltage detecting means when the power source voltage is greater than the reference value.

Claims

1. A shutter control device for a camera having (a) an automatic exposure time control device provided with a comparator circuit for comparing a time output corresponding to the lapse of time from the opening operation of a shutter with a proper shutter speed output representing a proper shutter speed and for generating a comparison output when said two outputs are in a predetermined relation and a magnet for blocking the closing operation of the shutter by energization, said magnet being adapted to be deenergized in response to said comparison output to close the shutter, and (b) a shutter release lock device provided with voltage detecting means for detecting a power source voltage and for deenergizing said magnet before the opening operation of the shutter when the power source voltage is below a reference value and blocking means for blocking the opening operation of the shutter by the deenergization of said magnet before the opening operation of the shutter, said shutter control device including means for forcibly energizing said magnet until the start of the opening operation of the shutter in response to shutter release operation, said means being operative in response to the output of said voltage detecting means when said power source voltage is greater than said reference value.

2. A shutter control device according to claim 1, wherein said means for forcibly energizing said magnet includes a pulse generating circuit for generating a pulse during the period of time from the shutter release operation until the start of opening operation of said shutter, and a switch adapted to permit a power supply to be fed to said magnet upon generation of a pulse by said pulse generator.

3. A shutter control device according to claim 1 or 2, further including display means for displaying said proper shutter speed output when said proper shutter speed output corresponds to a shutter speed higher than the controllable highest shutter speed.