Exposure control circuit for a camera having a load circuit

• US 4,607,931 A
• Filed: 11/30/1984
• Issued: 08/26/1986
• Est. Priority Date: 12/02/1983
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Aihara, Yoshihiko
• Primary Examiner(s): Adams, Russell E.
• Application Number:
  US06/676,545
• Time in Patent Office: 634 Days
• Field of Search: 354/400, 354/402, 354/406, 354/407, 354/408, 354/484, 354/173.1, 354/173.11, 354/412, 354/458, 354/460
• US Class Current: 396/133
• CPC Class Codes: G03B 7/0807 Control circuits G03B7/10 takes precedence
• CPC Class Codes: G03B 7/083 for control of exposure time
• CPC Class Codes: G03B 7/093 for control of exposure time

Abstract

A camera having a common electrical power source for the light metering circuit and either the range finding circuit or the lens drive motor. The output of the light metering circuit which occurs when the range finding circuit or the lens drive motor transits from unenergization to energization is prohibited from being used for automatically controlling exposure.

Claims

1. A camera system having an electric motor for driving a load member, comprising:

(a) a light metering circuit;

(b) an exposure control circuit for controlling exposure in accordance with the output of said light metering circuit;

(c) an electrical power supply circuit for supplying electrical power to said light metering circuit and said motor from a common battery; and

(d) prohibiting means for stopping the transfer of the output of said light metering circuit to said exposure control circuit for a prescribed time when current is supplied to said motor.

2. A camera system having an electric motor for driving a load member, comprising:

(a) a light metering circuit for producing an output proportional to the brightness level of an object to be photographed;

(b) a hold circuit having an input connected to the output of said light metering circuit and responsive to prohibition of the transfer of the output of said light metering circuit thereto for holding that output of said light metering circuit which has been transferred thereto before that prohibition until the output of said light metering circuit is allowed again to transfer;

(c) an exposure control circuit for controlling an exposure in accordance with the output of said hold circuit;

(d) an electrical power supply circuit for supplying electrical power to said light metering circuit and said motor from a common battery; and

(e) prohibiting means for stopping the transfer of the output of said light meeting circuit to said hold circuit for a prescribed time when said motor is supplied with electrical power.

3. A camera system having an electric motor for driving a photographic lens, comprising:

(a) a light metering circuit for producing a output proportional to the brightness level of an object to be photographed;

(b) a hold circuit having an input connected to the output of said light metering circuit and responsive to prohibition of the transfer of the output of said light metering circuit thereto for holding that output of said light metering circuit which has been transferred thereto before that prohibition until the output of said light metering circuit is allowed again to transfer;

(c) an exposure control circuit for controlling an exposure in accordance with the output of said hold circuit, said circuit being responsive to actuation of a camera release for initiating an exposure operation;

(d) an electrical power supply circuit for supplying electrical power to said light metering circuit and said motor from a common battery; and

(e) prohibiting means for stopping the transfer of the output of said light metering circuit to said hold circuit for a prescribed time when said motor is supplied with electrical power.

4. A camera system having a light metering circuit and a load circuit, comprising:

(a) a light metering circuit;

(b) an exposure control circuit for controlling exposure in accordance with the output of said light metering circuit;

(c) a power supply circuit for supplying electrical power to said light metering circuit and said load circuit from a common battery; and

(d) prohibiting means for stopping the transfer of the output of said light metering circuit to said exposure control circuit for a prescribed time when said load circuit is supplied with electrical power.

7. A camera system as in claim 4, 5 or 6 wherein said load circuit is a focus detecting circuit for detecting focus.

5. A camera system having a light metering circuit and a load circuit, comprising:

(a) a light metering circuit for producing an output proportional to the brightness level of an object to be photographed;

(b) a hold circuit having an input connected to the output of said light metering circuit and responsive to prohibition of the transfer of the output of said light metering circuit thereto for holding that output of said light metering circuit which has been transferred thereto before that prohibition until the output of said light metering circuit is allowed again to transfer;

(c) an exposure control circuit for controlling an exposure in accordance with the output of said hold circuit;

(d) a power supply circuit for supplying electrical power to said light metering circuit and said load circuit from a common battery; and

(e) prohibiting means for stopping the transfer of the output of said light metering circuit to said hold circuit for a prescribed time when said load circuit is supplied with electrical power.

6. A camera system having a light metering circuit and a load circuit, comprising:

(a) a light metering circuit for producing an output proportional to the brightness level of an object to be photographed;

(b) a hold circuit having an input connected to the output of said light metering circuit and responsive to prohibition of the transfer of the output of said light metering circuit thereto for holding that output of said light metering circuit which has been transferred thereto before that prohibition until the output of said light metering circuit is allowed again to transfer;

(c) an exposure control circuit for controlling an exposure in accordance with the output of said hold circuit, said circuit being responsive to actuation of a camera release for initiating an exposure operation;

(d) a power supply circuit for supplying electrical power to said light metering circuit and said load circuit from a common battery; and

(e) prohibiting means for stopping the transfer of the output of said light metering circuit to said hold circuit for a prescribed time when said load circuit is supplied with electrical power.

8. A camera system having a light metering circuit and a load circuit, comprising:

(a) a light metering circuit for producing an output proportional to the brightness level of an object to be photographed;

(b) an A/D converting circuit for converting the output of said light metering circuit by a prescribed period to renew the A/D converted value;

(c) an exposure control circuit for controlling an exposure in accordance with the output of said A/D converting circuit;

(d) a power supply circuit for supplying electrical power to said light metering circuit and said load circuit from a common battery; and

(e) a prohibiting circuit for prohibiting the renewing of the A/D converted value to be applied to said exposure control circuit for a prescribed time when said load is supplied with electrical power.

10. A camera system as in claim 8 or 9 wherein said load circuit is an electric motor for driving a photographic lens.

11. A camera system as in claim 8 or 9 wherein said load circuit is a focus detecting circuit for performing focus detection.

9. A camera system having a light metering circuit and a load circuit, comprising:

(a) a light metering circuit for producing an output proportional to the brightness level of an object to be photographed;

(b) an A/D converting circuit for converting the output of said light metering circuit by a prescribed period to renew the A/D converted value;

(c) a hold circuit receptive of a signal representing an A/D converted value by said A/D converting circuit for holding said received A/D converted value until another signal representing the next A/D converted value is applied thereto;

(d) an exposure control circuit for controlling an exposure in accordance with the A/D converted value held in said hold circuit, said circuit being responsive to actuation of a camera release for initiating an exposure operation;

(e) a power supply circuit for supplying electrical power to said light metering circuit and said load circuit from a common battery; and

(f) prohibiting means for stopping the transfer of the A/D converted value to said hold circuit for a prescribed time when said load circuit is supplied with electrical power.