Synchronizing speed warning apparatus for camera

• US 4,199,236 A
• Filed: 07/06/1978
• Issued: 04/22/1980
• Est. Priority Date: 08/15/1977
• Status: Expired due to Term

• Current Assignee: Nikon Corporation
• Original Assignee: Nippon Kotsu Kabushiki Kaisha (Nikon Corporation)
• Inventors: Hasegawa, Hiroshi, Goto, Tetsuro
• Primary Examiner(s): Gellner, Michael L.
• Application Number:
  US05/922,444
• Time in Patent Office: 656 Days
• Field of Search: 354/53, 354/60 L, 354/127, 354/128, 354/139, 354/149, 354/289, 354/5 D, 354/60 E
• US Class Current: 396/167
• CPC Class Codes: G03B 15/05 Combinations of cameras with electronic flash apparatus; Electronic flash units
• CPC Class Codes: G03B 2215/05 Combinations of cameras with electronic flash units

Abstract

A photographic camera for use in conjunction with a flash device is provided with a warning apparatus which provides a warning signal when a selected shutter speed is beyond a shutter speed range synchronizable with the light emission from the flash device. The warning apparatus comprises a circuit for providing a signal indicating that the selected shutter speed is faster than a limit shutter speed, beyond which the shutter cannot be synchronized with the flash. A charge detection circuit detects the completion of charging of the flash device. A warning indication that the selected shutter speed is faster than the limit shutter speed is provided only upon completion of charging of the flash device, thereby conserving battery power.

Claims

1. A warning apparatus for use in a photographic camera for providing a warning that a selected shutter speed is faster than a limit shutter speed beyond which the shutter is not synchronizable with the light emission from a flash device, comprising:

means for generating a standard voltage corresponding to the limit shutter speed;

means for generating an output voltage corresponding to the selected shutter speed;

comparator means for comparing said standard voltage and said output voltage and for generating a signal representative of the result of said comparison;

a charge completion detection circuit adapted for connection to the flash device for generating a charge completion signal upon completion of charging of the flash device; and

control means connected to said comparator means and said detection circuit and adapted for controlling a warning indicator to provide a warning indication upon receipt of both said charge completion signal and a signal from said comparator means indicating that the selected shutter speed is faster than the limit shutter speed.

2. A warning apparatus according to claim 1, wherein said means for generating an output voltage is adapted to generate an output voltage equal to said standard voltage when said selected shutter speed is equal to said limit shutter speed.

3. A warning apparatus according to claim 1, which further comprises:

means for measuring the quantity of light received from an object to be photographed; and

means for automatically selecting the shutter speed required for obtaining the proper exposure corresponding to the quantity of light measured.

4. A warning apparatus according to claim 1, wherein said means for generating an output voltage comprises:

a voltage dividing circuit having a plurality of series connected resistors;

a first output terminal connected to said voltage dividing circuit in such a manner as to provide an output voltage higher than said standard voltage;

a second output terminal connected to said voltage dividing circuit in such a manner as to provide an output voltage lower than said standard voltage; and

means for selectively deriving said output voltage from either one of said output terminals.

5. A warning apparatus according to claim 1, which further comprises:

means connected to said control means for inhibiting the operation of a shutter release mechanism of the camera upon the receipt by said control means of both said charge completion signal and said signal from said comparator means indicating that the selected shutter speed is faster than the limit shutter speed.