Electric camera shutter with voltage checking circuit

• US 3,886,443 A
• Filed: 05/29/1973
• Issued: 05/27/1975
• 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): Smith, Alfred E.
• Assistant Examiner(s): Hille, Rolf
• Application Number:
  US05/364,741
• Time in Patent Office: 728 Days
• Field of Search: 324/29.5 340/249 356/226 95/1C 317/52
• US Class Current: 324/426
• 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 in which a circuit for automatically determining the extent to which film is exposed has a voltage source and a checking circuit for checking the condition of the voltage source. The checking circuit includes a meter to indicate the condition of the voltage source, a resistor and a diode connected in series in a forward direction between the resistor and the meter, and a normally open switch between the resistor and the voltage source to be closed for connecting the resistor and diode to the meter so that the latter will give a reading indicating the condition of the voltage source. In this way the diode prevents the checking circuit from influencing the meter when the checking switch is not closed.

Claims

1. In a camera, circuitry for automatically determining the extent to which film in the camera is exposed, a voltage source, a main switch connected between said voltage source and said circuitry for transmitting voltage from said voltage source to said circuitry when said main switch is closed, meter means electrically connected with said circuitry for providing information with respect thereto, checking circuit means for checking the condition of said voltage source, said checking circuit means consisting of components which are entirely separate from said circuitry so that none of the components of said checking circuit means are in common with components of said circuitry, and including electronic thermal compensating means for thermally compensating the checking circuit means, said checking circuit means being operatively connected with said meter means for indicating at said meter means the condition of said voltage source, and a normally open switch electrically connected between said checking circuit means and said voltage source to be closed, when said main switch is open, for connecting said checking circuit means between said voltage source and said meter means so that the latter will give a reading indicating the condition of said voltage source.

2. In a camera, circuitry for automatically determining the extent to which film in the camera is exposed, a voltage source, a main switch connected between said voltage source and said circuitry for transmitting voltage from said voltage source to said circuitry when said main switch is closed, meter means electrically connected with said circuitry for providing information with respect thereto, checking circuit means for checking the condition of said voltage source, said checking circuit means consisting of components which are entirely separate from said circuitry so that none of the components of said checking circuit means are in common with components of said circuitry and said checking circuit means being operatively connected with said meter means for indicating at said meter means the condition of said voltage source, and a normally open switch electrically connected between said checking circuit means and said voltage source to be closed, when said main switch is open, for connecting said checking circuit means between said voltage source and said meter means so that the latter will give a reading indicating the condition of said voltage source, and wherein said checking circuit means includes resistor means and a diode connected in series in a forward direction between said resistor means and said meter means, and a grounded thermal compensating circuit means connected in parallel with the series connected resistor means and diode for preventing thermal influences from giving inaccuracies of the checking of the condition of said voltage source, so that said diode prevents said checking circuit means from influencing said meter means when said normally open switch is in said open position thereof.

3. The combination of claim 2 and wherein said circuitry includes a voltage supply means electrically connected with said meter means for operating the latter when said main switch is closed and said normally open switch is in said open position thereof, so that said meter means is connected to said voltage source only through said checking circuit means and otherwise is supplied from said voltage supply means.

4. The combination of claim 3 and wherein said voltage supply means is a voltage regulator providing a constant supply source for said meter means.