PHOTOGRAPHIC APPARATUS WITH LIQUID CRYSTAL VOLTAGE INDICATOR

• US 3,727,527 A
• Filed: 06/08/1972
• Issued: 04/17/1973
• Est. Priority Date: 06/11/1971
• Status: Expired due to Term

• Current Assignee: Alfred Kubitzek, Kurt Borowski
• Original Assignee: Alfred Kubitzek, Kurt Borowski
• Inventors: Borowski, Kurt, Kubitzek, Alfred
• Primary Examiner(s): Matthews, Samuel S.
• Assistant Examiner(s): Gellner, Michael L.
• Application Number:
  US05/261,038
• Time in Patent Office: 313 Days
• Field of Search: 350/16R 356/227 95/1R,1B,1CE
• US Class Current: 396/290
• CPC Class Codes: G01R 19/155 Indicating the presence of voltage
• 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 17/20 visible in viewfinder

Abstract

A still camera or motion picture camera wherein the exposure control circuit has an output at which the voltage is indicative of the prevailing scene brightness, of the selected aperture size, the selected exposure time and/or the sensitivity of film with which the camera is loaded. The output is connected with one electrode of a liquid crystal cell which is associated with a suitable scale to indicate the voltage at the output. If the voltage at the output is indicative of the aperture size, film speed and/or scene brightness, a reading of the scale (which is preferably observable by looking into the view finder) enables the user of the camera to properly select the exposure time. If the voltage at the output is indicative of the selected exposure time, film speed and/or scene brightness, the user can read the scale to properly adjust the aperture size. One of the two transparent electrodes in the liquid crystal cell may be of sinusoidal shape to further facilitate the determination of boundary between the transparent and non-transparent or differently colored portions of the liquid layer between the electrodes; such boundary travels in dependency on changes of voltage at the output.

Claims

1. In a photographic apparatus, a combination comprising an exposure control including an electric circuit having an output at which the voltage varies as a function of changes in at least one of a plurality of parameters including the exposure time, aperture size, scene brightness and film speed;

and indicating means for indicating the voltage at said output, including a liquid crystal cell having a layer of liquid crystal and two electrodes flanking said layer, one of said electrodes being connected with said output so that the difference of potential between said electrodes varies as a function of changes in voltage at said output with attendant changes in light transmissivity of different portions of said layer.

2. A combination as defined in claim 1, wherein said electrodes are transparent and further comprising scale means associated with said layer and calibrated to indicate different voltages at said output as a function of changes in the ratio of transparent and non-transparent or differently colored portions of said layer.

3. A combination as defined in claim 2, further comprising view finder means, said scale being observable by looking into said view finder means.

4. A combination as defined in claim 2, wherein said scale registers with said layer.

5. A combination as defined in claim 4, wherein said scale is outwardly adjacent to one of said electrodes and is observable through said layer.

6. A combination as defined in claim 2, wherein said scale is adjacent to one edge portion of said layer.

7. A combination as defined in claim 2, wherein said cell further comprises a transparent plate-like carrier for at least one of said electrodes and said scale forms part of said carrier.

8. A combination as defined in claim 1, wherein one of said electrodes is of meandering shape.

9. A combination as defined in claim 1, wherein said output is the intermediate tap of a voltage divider which forms part of said circuit and includes a pair of resistors one of which is variable as a function of changes in scene brightness.

10. A combination as defined in claim 9, wherein said circuit further comprises an energy source and said voltage divider comprises two additional taps connected with different poles of said energy source, one of said poles being further connected with said electrodes and the point of connection between said one pole and said one electrode being remote from the point of connection between said one electrode and said outpUt.