Source voltage monitor for a photographic camera

• US 5,500,710 A
• Filed: 12/15/1994
• Issued: 03/19/1996
• Est. Priority Date: 06/25/1992
• Status: Expired due to Fees

• Current Assignee: Fuji Photo Optical Co. Ltd (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Optical Co. Ltd (Fujifilm Holdings Corporation)
• Inventors: Onozuka, Haruo, Saito, Tatsuo
• Primary Examiner(s): Gellner, Michael L.
• Assistant Examiner(s): TUCCILLO, NICHOLAS
• Application Number:
  US08/357,091
• Time in Patent Office: 460 Days
• Field of Search: 354/484, 354/127.1, 354/418, 354/468, 354/473, 354/464, 354/127.12
• US Class Current: 396/277
• CPC Class Codes: G03B 7/093 for control of exposure time
• CPC Class Codes: G03B 7/26 Power supplies; Circuitry or arrangement to switch on the power source; Circuitry to check the power source voltage

Abstract

A source voltage monitor for a photographic camera is adapted to determine, prior to release, whether the source voltage is at a level sufficiently high for effective release for exposure. The monitor uses a predetermined reference voltage for the comparison, which voltage is selected independently of the selected mode of photographing. According to the invention, the source voltage is checked prior to release with a lens barrel driving circuit and/or a shutter blade driving circuit energized, depending on the selected mode of photographing. In the preflash mode, for example, both the lens barrel driving circuit and the shutter blade driving circuit are energized during the source voltage check. In low luminance automatic strobe discharge mode, only the lens barrel driving circuit is energized during the source voltage check.

Claims

1. A camera, comprising:

a film transporting circuit having a film transporting motor;

a lens barrel driving circuit having a lens barrel driving motor used to move the lens barrel, which holds an objective therein, selectively forward or backward to change a focal distance of the objective;

a shutter blade driving circuit having a shutter blade driving motor used to open and close shutter blades for every exposure;

a built-in strobe circuit;

a common power source;

a photographing mode selector for selecting one of a plurality of different photographing modes, the selected photographing mode requiring a particular power source voltage level during exposure;

a controller coupled to said mode selector and to said circuits for selectively enabling one or more particular ones of said circuits according to the mode of photographing selected by said selector in order to apply a load to the power source that will result in a power draw that is related to the selected photographing mode; and

a monitor coupled to said common power source, said monitor determining, prior to exposure, whether the source voltage is at a level sufficiently high for a selected mode of photographing, wherein said determination is performed by said monitor with said controller enabling said one or more particular ones of said circuits according to the selected mode of photographing, whereby the power drawn from said common power source is varied during testing according to the mode of photographing selected and wherein said monitor circuit determines whether the source voltage level is greater than a fixed reference voltage predetermined independently of the selected mode of photographing to check said source voltage.

2. The photographic camera as defined in claim 1, wherein said monitor circuit samples an output of said voltage source to generate a sampled voltage, and compares said sampled voltage to said fixed reference voltage which is predetermined independently of the selected mode of photographing to check said source voltage.

3. The photographic camera as defined in claim 1, wherein the mode of photographing is selected from a low luminance automatic strobe discharge mode, a preflash mode and a forcible strobe discharge mode.

4. The photographic camera as defined in claim 2, wherein said determination is performed with the lens barrel driving circuit energized and the shutter blade driving circuit disabled in the low luminance automatic strobe discharge mode.

5. The source voltage monitor for a photographic camera as defined in claim 3, wherein said determination is performed with the lens barrel driving circuit and the shutter blade driving circuit energized in the preflash mode.

6. The photographic camera as defined in claim 2, wherein said determination is performed with the lens barrel driving circuit energized and the shutter blade driving circuit disabled in the forcible strobe discharge mode.

7. The photographic camera as defined in claim 3, wherein said monitor circuit samples an output of said voltage source to generate a sampled voltage and compares the sampled voltage to said fixed reference voltage which is predetermined independently of the selected mode of photographing to check said source voltage.

8. The photographic camera as defined in claim 1, wherein the mode of photographing is selected from a low luminance automatic strobe discharge mode, a preflash mode, a forcible strobe discharge mode and a forcible strobe disable mode.

9. The photographic camera as defined in claim 8, wherein said determination is performed with the shutter blade driving circuit energized and the shutter blade driving circuit disabled in the forcible strobe disable mode.

10. The photographic camera as defined in claim 8, wherein said determination is made with the lens barrel driving circuit being energized and the shutter blade driving circuit disabled in the low luminance automatic strobe discharge mode.

11. The photographic camera as defined in claim 3, wherein said determination is made with said lens barrel driving circuit and the shutter blade driving circuit energized in the preflash mode.

12. The photographic camera as defined in claim 8, wherein the determination is made with the lens barrel driving circuit being energized and the shutter driving circuit disabled in the forcible strobe discharge mode.

13. The photographic camera as defined in claim 8, wherein said monitor circuit samples an output of said voltage source to generate a sampled voltage and compares the sampled voltage to the fixed voltage which is predetermined independently of the selected mode of photographing.

14. A photographic camera comprising:

a film transporting circuit having a film transporting motor;

a lens barrel driving circuit including a lens barrel driving motor used to move the lens barrel which holds the objective therein selectively forward or backward to change a focal distance of the objective;

a shutter blade driving circuit including a shutter blade driving motor used to open and close shutter blades for every exposure;

a built-in circuit strobe;

a common power source coupled to said circuits and providing energizing power to said circuits;

a mode selector for selecting one of a plurality of different operating modes of photographing, the selected mode of photographing requiring a particular power source voltage level during exposure;

a controller selectively energizing said circuits;

a fixed reference signal generator outputting a fixed reference signal; and

a source voltage monitor including a monitor circuit coupled to said fixed reference generator and said voltage generator, said monitor determining prior to exposure, whether said source voltage is at a level greater than said fixed reference signal such that it has a sufficient power to energize said shutter blade driving motor for the selected mode of photographing;

wherein said controller selectively enables one or more of said circuits depending on the mode selected concurrently with said source voltage monitor determining whether the source voltage is at a level greater than the fixed reference signal, wherein the power drawn from said power source is varied as a function of the selected mode of photographing, and wherein a process of shutter control is run resulting in exposure when the source voltage has been determined to be higher than said fixed reference level signal and a process of release disabling is run inhibiting exposure when the source voltage is detected to be lower than said fixed reference level signal.

15. A photographic camera comprising:

a lens barrel driving circuit including a lens barrel driving motor used to move the lens barrel holding an objective therein forward and backward to change a focal distance of the objective;

a shutter blade driving circuit having a shutter blade driving motor used to open and close shutter blades for every exposure;

a built-in strobe;

a common power source coupled to said circuits and having an output power;

a photographing mode selector selecting one of an automatic strobe discharge mode, a preflash mode, a forcible strobe discharge mode and a forcible strobe disable mode;

a fixed reference signal;

a monitor circuit coupled to said fixed reference signal and to said common power source, said monitor comparing said output power of said power source to said reference signal, and disabling said shutter release motor if said power output is less than said reference signal; and

a control circuit coupled to said mode selector, said film transporting circuit, said lens barrel driving circuit, said shutter blade driving circuit, and said strobe driving circuit for selectively controlling energization of said circuits during said comparing, wherein particular one or ones of said circuits are energized depending upon the photographing mode selected by said mode selector, whereby the power drawn from said power source is varied during testing according to the photographing mode selected, such that the power source must output more power in some of said photographing modes than in other ones of said photographing modes for said power source to exceed said fixed reference signal level and said shutter is released for photographing.

16. The photographic camera as defined in claim 15, wherein said determination is performed with the lens barrel driving circuit energized and the shutter blade driving circuit disabled in the low luminance automatic strobe discharge mode.

17. The photographic camera as defined in claim 15, wherein said determination is performed with the lens barrel driving circuit energized and the shutter blade driving circuit disabled in the forcible strobe discharge mode.

18. The photographic camera as defined in claim 15 wherein said determination is performed with the shutter blade driving circuit energized in the forcible strobe disable mode.