ELECTRIC CAMERA SHUTTER WITH LIGHT RESPONSIVE CONTROLS

• US 3,768,391 A
• Filed: 05/09/1972
• Issued: 10/30/1973
• Est. Priority Date: 05/12/1971
• Status: Expired due to Term

• Current Assignee: Nobuhiro Noda, Seinan Miyakawa
• Original Assignee: Nobuhiro Noda, Seinan Miyakawa
• Inventors: Miyakawa, Seinan, Noda, Nobuhiro
• Primary Examiner(s): Matthews, Samuel S.
• Assistant Examiner(s): Gellner, Michael L.
• Application Number:
  US05/251,761
• Time in Patent Office: 539 Days
• Field of Search: 95/1CT,53EB
• US Class Current: 396/228
• CPC Class Codes: G03B 7/083 for control of exposure time

Abstract

A camera capable of automatically determining the extent to which the film is exposed either when using automatic objectives which are stopped down to a preselected aperture automatically just prior to exposure or objectives which are manually stopped down, with light which is measured passing through the latter type of objective with its stopped down diaphragm. In order to introduce into the circuitry the factor of the size of the exposure aperture, a pair of variable resistors are provided to be used with the above different types of objectives, respectively, and when the variable resistor to be used with the non-automatic objective operates, a bypass switch, which bypasses the other variable resistor, is closed, so as to provide a proper signal according to the type of objective which is used. In addition, when making an exposure of extremely short duration, controls are provided to deenergize an electromagnet which releases a trailing curtain in an extremely short time which does not require the interval usually required for the response of the circuitry to the various exposure-determining factors. Also, the camera includes an indicator which is available for indicating the exposure time to the operator in such a way that this indication does not in any way interfere with the functioning of the circuitry which automatically determines the exposure.

Claims

1. In a camera having circuitry for automatically determining the extent to which film in the camera is exposed, said circuitry including a circuit for providing a signal according to the magnitude of the exposure aperture, the latter circuit comprising a first variable resistor means for providing said aperture signal when using an objective which has a wide open diaphragm for providing a preselected aperture automatically just prior to exposure, bypass switch means electrically connected with said first variable resistor means for bypassing the latter when using an objective having a diaphragm which is not automatically stopped down just prior to exposure so that when using the latter objective with measurement of light passing therethrough the light measurement is influenced by the diaphragm which is in a stopped down condition, second variable resistor means connected in parallel with said first variable resistor means for providing a signal corresponding to that of said first varaible resistor means when using an objective having a diaphragm which is not automatically stopped down just prior to exposure, said first and second variable resistor means respectively having adjustable components for adjusting the settings of said first and second variable resistor means, and change-over switch means electrically connected with said adjustable components for electrically connecting one or the other of said components to said circuitry, said bypass switch means by-passing said first variable resistor means to prevent erroneous operation when said adjustable component of said second variable resistor means should be but is not connected to said circuitry by said changeover switch means.

2. The coMbination of claim 1 and wherein said circuitry includes a third variable resistor means connected in parallel with said first and second variable resistor means for introducing a signal according to the speed of the film which is exposed.

3. The combination of claim 1 and wherein said circuitry includes a light-responsive means for responding to light at the object to be photographed for introducing a signal according to the latter light, said change-over switch means being electrically connected to said light-responsive means.

4. The combination of claim 3 and wherein said light-responsive means includes a photosensitive element for receiving light from the object to be photographed and a logarithmic compression diode electrically connected in series with said photosensitive element, said changeover switch means being electrically connected to a junction between said photosensitive element and said diode.

5. The combination of claim 1 and wherein said bypass switch means is electrically connected between said first variable resistor means and said adjustable component thereof.