COMBINED BATTERY TEST AND LIGHT METER FOR A PHOTOGRAPHIC CAMERA

• US 3,699,857 A
• Filed: 07/08/1970
• Issued: 10/24/1972
• Est. Priority Date: 07/12/1969
• Status: Expired due to Term

• Current Assignee: Bernhard Von Fischern, Karl Wagner
• Original Assignee: Bernhard Von Fischern, Karl Wagner
• Inventors: Wagner, Karl, VON Fischern, Bernhard
• Primary Examiner(s): Matthews, Samuel S.
• Assistant Examiner(s): Gellner, Michael L.
• Application Number:
  US05/053,249
• Time in Patent Office: 839 Days
• Field of Search: 95/1CE,1CT
• US Class Current: 396/279
• CPC Class Codes: G03B 7/083 for control of exposure time

Abstract

Indicator lamps for indicating sufficient and insufficient light for exposure are used for battery testing by connecting them in the emitter circuit of a switching transistor whose base voltage is controlled by a voltage divider in parallel with the battery. The voltage divider is adjusted to allow the lamp to light if the battery voltage exceeds the proper operating voltage or if the battery voltage is between a minimum acceptable voltage and the operating voltage. Otherwise the indicator lamps do not light regardless of the light available for exposure.

Claims

1. In a camera, a combined battery and available light test arrangement, comprising, in combination, indicator means, furnishing, only when energized, a first output in the presence of sufficient light for an exposure and a second output in the absence of sufficient light for an exposure;

battery means having a battery output voltage; and

threshold circuit means responsive only to a threshold voltage corresponding to said battery output voltage independent of available light, or connecting said battery means to said indicator means thereby energizing the latter only when said battery output voltage exceeds a predetermined battery output voltage, whereby the presence of said first or said second output of said indicator means indicates the battery output voltage exceeding said predetermined battery output voltage.

2. A camera as set forth in claim 1, wherein said indicator means comprise at least one indicator lamp.

3. A camera as set forth in claim 2, wherein said indicator means comprise a first and second indicator lamp, respectively indicative of sufficient and insufficient light for an exposure when lit.

4. A camera as set forth in claim 3, wherein each of said lamps has a different color.

5. A camera as set forth in claim 3, further comprising a light sensitive element connected to said battery, the current through said light sensitive element varying in dependence upon the light impinging thereon;

moving coil means connected to said light sensitive element; and

means for energizing said first or said second indicator lamp in dependence upon the position of said moving coil means.

6. A camera as set forth in claim 5, wherein said means for energizing said first or said second indicator lamp comprise a conducting arm connected to said moving coil means;

a first contact segment connected to said first indicator lamp;

a second contact segment connected to said second indicator lamp, said conducting arm contacting said first or said second contact segment in dependence upon the current through said moving coil means.

7. A camera as set forth in claim 6, wherein said moving arm contacts said first contact segment when insufficient light is present for exposure and said second contact segment when sufficient light is present for exposure.

8. A camera as set forth in claim 2, further comprising moving coil means having a conducting arm deflecting in dependence upon the light available for exposure;

transluscent window means having a first and second color, connected to said conducting arm for movement therewith, and positioned relative to said indicator lamp to cover said indicator lamp with said first or second color depending upon the movement of said conducting arm, whereby an illuminated first transluscent window color constitutes said first output and illuminated second transluscent window color constitutes said second output.

9. A camera as set forth in claim 1, wherein said threshold circuit means comprise a switching transistor having an emitter, a base, and a collector;

first voltage divider means connected in parallel with said battery and having a voltage divider tap connected with the base of said switching transistor; and

means connecting said indicator lamp to the emitter of said switching transistor.

10. A camera as set forth in claim 9, wherein said first voltage divider means comprise a variable resistance, thereby permitting adjustment of said predetermined threshold voltage.

11. A camera as set forth in claim 10, further comprising an automatic exposure control circuit having an output transistor and a shutter control relay;

and indicator switching means selectively connecting either said shutter control relay or said first indicator lamp with said output transistor.

12. A camera as set forth in claim 11, further comprising an inverter transistor connected with said output transistor;

and wherein said indicator switching means further comprise additional switching means selectively connecting or disconnecting said second indicator lamp from said inverter transistor.

13. A camera as set forth in claim 12, wherein said output transistor has a collector;

wherein said inverter transistor has a base, said base of said inverter transistor being connected to said collector of said output transistor.

14. A camera as set forth in claim 9, wherein said first voltage divider means comprise a first, second and third resistance;

and a battery test switch for selectively connecting said first or said third resistance in series with said second resistance, thereby permitting adjustment of said threshold voltage to an operating threshold voltage and a minimum threshold voltage, corresponding, respectively, to a desired operating battery output voltage and a minimum battery output voltage permitting only a limited number of subsequent camera operations.

15. A camera as set forth in claim 14 further comprising a battery test button for operating said battery test switch.

16. A camera as set forth in claim 14, further comprising moving coil means having a conducting arm deflected in dependence upon the light available for exposure;

translucent window means connected to said conducting arm for movement therewith and positioned relative to said indicator lamp to cover said indicator lamp with one of said colors depending upon the movement of said conducting arm; and

wherein said battery test switch comprises a first contact segment connected to said first resistance, a second contact segment connected to said third resistance, and means connecting said conducting arm with said second resistance.

17. A camera as set forth in claim 9, wherein said first voltage divider means comprise variable resistance means.