ELECTRIC CAMERA SHUTTER WITH ENERGY CONTROLS

• US 3,776,116 A
• Filed: 05/09/1972
• Issued: 12/04/1973
• Est. Priority Date: 05/13/1971
• Status: Expired due to Term

• Current Assignee: Mitsuhiko Shimoda, Seinan Miyakawa
• Original Assignee: Mitsuhiko Shimoda, Seinan Miyakawa
• Inventors: Miyakawa, Seinan, Shimoda, Mitsuhiko
• Primary Examiner(s): Peters, Jr., Joseph F.
• Application Number:
  US05/251,764
• Time in Patent Office: 574 Days
• Field of Search: 95/1CT,53EB 317/123,148.5,157
• US Class Current: 396/465
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G03B 7/26 Power supplies; Circuitry or arrangement to switch on the power source; Circuitry to check the power source voltage
• CPC Class Codes: G03B 9/58 Means for varying duration of "open" period of shutter

Abstract

A camera which is capable of automatically determining the extent to which film in the camera is exposed. In order to terminate an exposure an electromagnet is deenergized in order to release a trailing shutter curtain. The circuitry provides for the electromagnet when it is deenergized an operation which will prevent any delay due to counter electromotive force generated when the electromagnet is deenergized. Also the circuitry has a voltage source which is capable of being checked. This checking of the condition of the voltage source takes place by way of a checking circuit which includes a resistor and series-connected diode connected to a meter which indicates the condition of the voltage source. A switch is capable of connecting the voltage source to this circuit when the voltage source is to be checked. The diode is connected between the meter and the remainder of the checking circuit in a forward direction so that the meter will not be influenced in any way by the checking circuit when the latter is not operated. Furthermore, the circuitry includes a light-responsive circuit and a signal-transmitting circuit for participating in the determination of the extent of exposure, and a constant voltage is supplied by the circuitry to both of these latter circuits for controlling them with compensation also for any thermal variations which may occur.

Claims

1. In a camera having circuitry for automatically determining the extent to which film in the camera is exposed, said circuitry including an electromagnetic means for terminating exposure when said electromagnetic means becomes unenergized, switching circuit means electrically connected to said electromagnetic means for controlling the latter, signal-transmission means electrically connected to said switching circuit means for transmitting to the latter signals for determining when said switching circuit means deenergizes said electromagnetic means, said switching circuit means including a means electrically connected with said eelectromagnetic means for supplying a rippled direct current thereto for preventing delay due to counter electromotive force generated when said electromagnetic means becomes deenergized.

2. The combination of claim 1 and wherein said switching circuit means includes a transistor electrically connected to said electromagnetic means for maintaining the latter energized while said transistor is conductive, said switching circuit means including a switching element which assumes a conductive condition when said electromagnetic means is to be deenergized, and a Zener diode electrically connected between said switching element and said transistor for remaining conductive while said switching element is in a non-conductive state and for instantly assuming a non-conductive state transferring said transistor to a non-conductive state and deenergizing said electromagnetic means when said switching element assumes a conductive condition, said Zener diode forming said means for preventing a delay due to said counter electromotive force.

3. The combination of claim 2 and wherein said circuitry includes a voltage regulator electrically connected to said Zener diode for applying thereto a voltage higher than its Zener voltage.

4. The combination of claim 3 and wherein said switching element is a thyristor having an anode to which said Zener diode is electrically connected.