CAMERA WITH ELECTRICAL CONTROLS FOR DIFFERENT TYPES OF OBJECTIVES

• US 3,839,722 A
• Filed: 04/23/1973
• Issued: 10/01/1974
• Est. Priority Date: 05/14/1971
• Status: Expired due to Term

• Current Assignee: Mitsuhiko Shimoda, Nobuhiro Noda, Seinan Miyakawa
• Original Assignee: Mitsuhiko Shimoda, Nobuhiro Noda, Seinan Miyakawa
• Inventors: Noda, Nobuhiro, Shimoda, Mitsuhiko, Miyakawa, Seinan
• Primary Examiner(s): Matthews, Samuel S.
• Assistant Examiner(s): Adams, Jr., Russell E.
• Application Number:
  US05/353,886
• Time in Patent Office: 526 Days
• Field of Search: 95/1C
• US Class Current: 396/228
• CPC Class Codes: G03B 7/083 for control of exposure time

Abstract

A camera capable of automatically determining the exposure time and having interchangeable objectives. One of the factors which determines the extent of exposure is the magnitude of the aperture through which light enters the camera. This factor is introduced either by way of one variable resistor which coacts with an objective which remains wide open and which is automatically stopped down to a preselected aperture just prior to exposure, or by way of a second variable resistor adapted to be used in the situation where the objective is not automatically stopped down just prior to exposure and instead has its diaphragm in a stopped down condition restricting travel of light passing through the objective with this light being measured after passing through the stopped down diaphragm. These variable resistors are connected in parallel and a selecting switch is provided for utilizing one or the other of the variable resistors depending upon the type of objective which is used.

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 introducing a signal according to a preselected diaphragm setting when using an objective which has a wide open aperture which is automatically stopped down to the preselected aperture just prior to exposure, second variable resistor means for introducing a signal according to the magnitude of the exposure aperture when using an objective which is not automatically stopped down to a preselected aperture, so that with the latter objective light measured after passing therethrough is restricted by the stopped down aperture, a bypass switch means connected across said first variable resistor means for introducing from said first variable resistor means a signal equal to that introduced by said second variable resistor means when said bypass switch means is in a closed state, said first and second variable resistor means being connected in parallel with each other and at least one of said variable resistor means including an electrically conductive adjustable component for determining the setting of said one variable resistor means, and switch means operatively connected with said component for selectively connecting the latter to said circuitry.

2. The combination of claim 1 and wherein a third variable resistor means having at least one adjustable component for determining the setting thereof is connected in parallel with said first and second variable resistor means for introducing a signal according to a predetermined exposure-determining factor.

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 in accordance with the lighting conditions, said change over switch means being electrically connected with 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 for responding thereto to provide an electrical quantity in accordance with the intensity of the light at the object to be photographed, a diode connected in series with said photosensitive element, and said switch means being electrically connected to a junction between said photosensitive element and said diode.

5. The combination of claim 1 and wherein both said first and said second variable resistor means include electrically conductive adjustable components for determining the settings of said first and second variable resistor means, said change over switch means being electrically connected with said components for selectively connecting one or the other of said components to said circuitry.

6. The combination of claim 2 and wherein said exposure-determining factor is the speed of the film which is exposed.

7. The combination of claim 5 and wherein said circuitry includes a light-responsive means for responding to light at the object to be photographed for introducing a signal in accordance with the lighting conditions, said change over switch means being electrically connected with said light-responsive means.

8. The combination of claim 7 and wherein said light-responsive means includes a photosensitive element for receiving light from the object to be photographed and for responding thereto to provide an electrical quantity in accordance with the intensity of the light at the object to be photographed, a diode connected in series with said photosensitive element, and said change over switch means being electrically connected to a junction between said photosensitive element and said diode.

9. The combination of claim 1 and wherein said bypass switch means is a normally open switch means which is automatically closed when using an objective which is not automatically stopped down.