Ready-to-flash condition indicating device for a camera

• US 4,370,042 A
• Filed: 05/04/1981
• Issued: 01/25/1983
• Est. Priority Date: 06/03/1980
• Status: Expired due to Term

• Current Assignee: Nikon Corporation
• Original Assignee: Nippon Kotsu Kabushiki Kaisha (Nikon Corporation)
• Inventors: Ohkubo, Yuji
• Primary Examiner(s): Perkey, William B.
• Application Number:
  US06/260,382
• Time in Patent Office: 631 Days
• Field of Search: 354/27, 354/32-35, 354/53, 354/60 R, 354/60 E, 354/60 L, 354/60 F, 354/127, 354/128, 354/139, 354/145, 354/149, 354/289, 315/241 P, 315/129, 315/136
• US Class Current: 396/203
• CPC Class Codes: G03B 17/18 Signals indicating condition of a camera member or suitability of light indicating depth of field G03B13/30
• CPC Class Codes: G03B 7/16 in accordance with both the intensity of the flash source and the distance of the flash source from the object, e.g. in accordance with the "guide number" of the flash bulb and the focusing of the camera

Abstract

A device in a camera is provided with a light-emitting element driven by a signal current from an electronic flash device to emit light and indicate the ready-to-flash condition of the electronic flash device, a current control circuit series-connected to the light-emitting element to control a current flowing to the light-emitting element, an integrated circuit operative in response to the signal current from the electronic flash device, and a limiting circuit for detecting a voltage related to the combined voltage of the light-emitting element and the current control circuit and limiting an applied voltage applied to the integrated circuit so as to be below a predetermined value when said voltage exceeds a predetermined value.

Claims

1. A device for use with an electronic flash device in a camera, comprising;

a light-emitting element driven by a signal current from said electronic flash device for indicating the ready-to flash condition of said electronic flash device;

a current control circuit series-connected to said light-emitting element to control a current flowing to said light-emitting element, an integrated circuit operative in response to said signal current from said electronic flash device; and

a limiting circuit for detecting a voltage related to the combined voltage of said light-emitting element and said current control circuit and limiting said combined voltage to below a predetermined value when said detected voltage exceeds a predetermined value.

2. A device according to claim 1, wherein said current control circuit is a constant current circuit which controls to a predetermined value the current flowing to said light-emitting element, and further comprising a power source voltage detecting circuit (55, 56, 63, 64) for detecting the power source voltage of said camera and producing a detection output when said power source voltage is below a predetermined value, and means (51, 52, 53) for forcibly turning off said light-emitting element in response to said detection output.

3. A device according to claim 1, wherein said limiting circuit is constituted by a Zener diode.

4. A device according to claim 1, wherein said limiting circuit is constituted by a detecting circuit (54) for detecting the combined voltage, and a shunt circuit (62) for shunting the current flowing to said light-emitting element in response to the output of said detecting circuit.