Automatic exposure control device

• US 4,657,368 A
• Filed: 02/10/1986
• Issued: 04/14/1987
• Est. Priority Date: 12/24/1981
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kawamura, Masaharu
• Primary Examiner(s): PERKEY, WILLIAM B
• Application Number:
  US06/828,578
• Time in Patent Office: 428 Days
• Field of Search: 354/446, 354/412, 354/451-453, 354/455, 354/271.1, 354/270, 354/272, 352/121, 352/141
• US Class Current: 396/262
• CPC Class Codes: G03B 7/095 for control of aperture

Abstract

An automatic exposure control device for a continuous photographing in a single lens reflex camera with an automatic exposure control system in which exposure control is effected by sensing a light beam passing through a phototaking lens and continuous photographing can be made. A device for discriminating a continuous photographing mode is provided and, when the continuous photographing mode is selected, a first photographing action to carry out an automatic exposure control by a full-open photometry is performed after a release action, and, then, for a photographing action thereafter, the light beam passing through a diaphragm aperture regulated by a preceding photographing action is sensed. A diaphragm mechanism is thereby regulated for carrying out the next photographing action.

Claims

1. In a camera having means for adjusting an aperture opening, by using an electro-driven means and a light metering circuit receptive of light passing through said aperture opening, whereby after a light metering operation has been carried out, an exposure operation is executed, said camera including:

(a) an aperture signal forming circuit for producing an aperture control signal;

(b) means for detecting an aperture opening condition controlled by said aperture adjusting means, said detecting means determining whether or not the aperture opening condition is suited for the light metering operation and producing an output when the aperture opening is not in the condition suited for the light metering operation;

(c) a diaphragm drive circuit responsive to the output of said detecting means for driving said aperture adjusting means in a direction to the aperture opening condition for light metering during the light metering operation before said exposure operation;

(d) inhibiting means for inhibiting the response to the output of the detecting means of the diaphragm drive circuit by a shutter release operation, the camera being shifted from said light metering operation to said exposure operation by the shutter release operation; and

(e) a control circuit for transferring the aperture control signal from said aperture signal forming circuit to said drive circuit when in the exposure operation, thereby the aperture opening is changed to a condition corresponding to said aperture control signal.

2. A camera according to claim 1, wherein said electro-driven means is an electromagnetically operated motor.

3. A camera according to claim 1, wherein said diaphragm drive circuit has a pulse forming circuit and said electro-driven means is driven by pulses from said pulse forming circuit and transfers the pulses to the electro-driven means in response to the outputs of said detecting means while said outputs are being formed.

4. A camera capable of performing successive photography by continuously repeating photographic operation, comprising:

(a) diaphragm means for electromagnetically controlling an aperture opening;

(b) a light metering circuit for metering the light coming through said aperture opening; and

(c) a diaphragm control circuit for controlling said diaphragm means according to an output of said light metering circuit before the taking of each photograph, said diaphragm means holding the aperture controlled before the taking of a photograph even after completion of the taking of a prior photograph, whereby the aperture state after completion of the taking of a photograph is transferred to an aperture opening for the taking of a next photograph according to the metering output of the light coming through said aperture opening.

5. A camera according to claim 4, wherein said diaphragm control circuit controls an aperture opening of a subsequent photography in accordance with a difference between the light metering output through an aperture opening representing the diaphragm value of a preceding photography and the diaphragm value of the preceding photography.

6. A camera according to claim 4, wherein said diaphragm control circuit has a pulse forming circuit and a signal path for transferring to said diaphragm means a number of pulses corresponding to the light metering output at the time of a subsequent photography.

7. A camera having a first mode in which photography is carried out at every operation of a release operation member and a second mode in which photography is continuously repeated while the release operation member is being operated, comprising:

(a) diaphragm means for electromagnetically controlling an aperture opening;

(b) a light metering circuit for metering the light coming through said aperture opening; and

(c) an aperture control circuit for transforming the diaphragm means after completion of the taking of a photograph to a fully opened state in the first mode and for controlling the aperture opening by controlling the diaphragm means according to a light metering output on the basis of the light coming through the aperture opening the fully opened state at the time of the next photograph taking by operation of the release operation member, said circuit transferring the aperture state after completion of the taking of a photograph to the aperture for the taking of the next photograph according to the metering output of the light coming through the aperture opening while the aperture opening after completion of the taking of a photograph is maintained in the second mode.

8. A camera according to claim 7, wherein said aperture control circuit has a pulse forming circuit and a signal path for transferring the pulse from the pulse forming circuit to the diaphragm means after completion of photography in a direction to open the aperture in the first mode, said signal path being prohibited in the second mode.

9. A camera capable of performing successive photography by continuously repeating photographic operation, comprising:

(a) diaphragm means for defining an aperture opening;

(b) a light metering circuit for metering the light coming through said aperture opening; and

(c) a diaphragm control circuit for controlling said diaphragm means according to an output of said light metering circuit before the taking of each photograph, said diaphragm means holding the aperture controlled before the taking of a photograph even after completion of the taking of a prior photograph, whereby the aperture state after completion of the taking of a photograph is transferred to an aperture opening for the taking of a next photograph according to the metering output of the light coming through said aperture opening.

10. A camera having a first mode in which photography is carried out at every operation of a release operation member and a second mode in which photography is continuously repeated while the release operation member is being operated, comprising:

(a) diaphragm means for defining an aperture opening;

(b) a light metering circuit for metering the light coming through said aperture opening; and

(c) an aperture control circuit for transforming the diaphragm means after completion of the taking of a photograph to a fully opened state in the first mode and for controlling the aperture opening by controlling the diaphragm means according to a light metering output on the basis of the light coming through the aperture opening in the fully opened state at the time of the next photograph taking by operation of the release operation member, said circuit transferring the aperture state after completion of the taking of a photograph to the aperture for the taking of the next photograph according to the metering output of the light coming through the aperture opening while the aperture opening after completion of the taking of a photograph is maintained in the second mode.

11. A camera according to claim 9 or 10, wherein said diaphragm means controls the aperture opening electro-optically.

12. A camera transferrable from a light metering mode into an exposure mode by the operation of a shutter release operation member comprising:

(a) diaphragm means;

(b) a light metering circuit for metering the light coming through an opening formed by the diaphragm means;

(c) an opening control circuit for detecting whether the diaphragm means is in a fully opened state or not in a light metering mode before the operation of the shutter release operation member and for producing an output when the diaphragm is not in the fully opened state so as to transfer the diaphragm means to the fully opened state, said circuit being made inoperative by the operation of the shutter release operation member; and

(d) an aperture control circuit for generating a signal for shifting the opening of the diaphragm means to a preset aperture value.

16. A camera according to claim 12, 13, 14 or 15, wherein said diaphragm means is driven by the electro-driven means.

17. A camera according to claim 12, 13, 14 or 15, wherein said diaphragm means is driven by the electro-motor.

18. A camera according to claim 12, 13, 14 or 15, wherein said aperture control circuit transfers the shifting signal to the diaphragm means by the operation of the shutter release operation member.

13. A camera transferrable from a light metering mode into an exposure mode by the operation of a shutter release operation member comprising:

(a) diaphragm means;

(b) a light metering circuit for metering the light coming through an opening formed by the diaphragm means;

(c) an opening control circuit for generating a signal for transferring the diaphragm means into a fully opened state in the light metering mode before the operation of the shutter release operation member so as to transfer the diaphragm means into the fully opened state, said circuit being made inoperative by the operation of the release operation member; and

(d) an aperture control circuit for generating a signal for shifting the opening of the diaphragm means to a preset aperture value.

14. A camera transferable from a light metering mode into an exposure mode by the operation of a shutter release operation member comprising:

(a) diaphragm means;

(b) a light metering circuit for metering the light coming through an opening formed by the diaphragm means;

(c) an opening control circuit for detecting whether the diaphragm means is in a fully opened state or not in a light metering mode before the operation of the shutter release operation member and for producing an output when the diaphragm is not in the fully opened state so as to transfer the diaphragm means to the fully opened state, said circuit being made inoperative by the operation of the shutter release operation member; and

(d) an aperture control circuit for generating a signal for shifting the opening of the diaphragm means to an aperture value according to the metering output of the light.

15. A camera transferable from a light metering mode into an exposure mode by the operation of a shutter release operation member, comprising:

(a) diaphragm means;

(b) a light metering circuit for metering the light coming through an opening formed by the diaphragm means;

(c) an opening control circuit for generating a signal for transferring the diaphragm means into a fully opened state in the light metering mode before the operation of the shutter release operation member so as to transfer the diaphragm means into the fully opened state, said circuit being made inoperative by the operation of the release operation member; and

(d) an aperture control circuit for generating a signal for shifting the opening of the diaphragm means to an aperture value according to the metering output of the light.