Apparatus for performing exposure control pertaining to the luminance level of an object

• US 5,559,555 A
• Filed: 05/16/1995
• Issued: 09/24/1996
• Est. Priority Date: 06/17/1993
• Status: Expired due to Term

• Current Assignee: SGS-Thomson Microelectronics (STMicroelectronics NV)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Kuroda, Osamu, Takahashi, Yoshikazu, Ito, Yasutaka, Shimizu, Shuji
• Primary Examiner(s): Garber, Wendy
• Assistant Examiner(s): Ho, Tuan V.
• Application Number:
  US08/442,495
• Time in Patent Office: 497 Days
• Field of Search: 348/207, 348/362, 348/363, 348/364, 348/229, 348/234, 348/235, 354/410, 354/412
• US Class Current: 348/364
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 23/6812 based on additional sensors, e.g. acceleration sensors
• CPC Class Codes: H04N 23/684 performed by controlling the image sensor readout, e.g. by controlling the integration time
• CPC Class Codes: H04N 23/6842 by controlling the scanning position, e.g. windowing
• CPC Class Codes: H04N 23/72 Combination of two or more compensation controls

Abstract

An exposing apparatus comprises: a lens group to fetch a light from an object; an iris to adjust a light amount from the lens group; an image pickup device to convert the light which passed through the iris into the electric signal; a detecting circuit to detect a luminance signal level from an output signal from the image pickup device; a reference level signal setting circuit to set an exposure control reference value to control the iris; an exposure control reference value modulating circuit to modulate the exposure control reference value when the iris is controlled; and a control circuit to set the exposure control reference value in correspondence to the luminance signal level when an output level of the detecting circuit is larger than a set value.

Claims

1. An exposing apparatus in a video camera, comprising:

a lens group for fetching a light from an object;

an iris for adjusting an amount of light from said lens group;

an image pickup device for converting the light which passed through said iris into an electric signal;

an AGC circuit for setting a signal level of an output signal from said image pickup device into a predetermined level;

a detecting circuit for detecting a luminance signal level from an output signal from said AGC circuit;

a reference level signal setting circuit for supplying an exposure control reference value;

an exposure control reference value modulating circuit for modulating said exposure control reference value, said exposure control reference value modulating circuit comprising

a luminance level operating circuit to which a gain of said iris and a gain amount of said AGC circuit are supplied; and

an ROM having a reference level modulation coefficient according to a luminance level, and wherein an output signal from said ROM and an output signal from said reference level signal setting circuit are multiplied so as to form a modulation signal; and

control means for receiving said modulation signal and said luminance signal level and for producing a plurality of control signals therefrom, said control signals being respectively utilized to control said iris, said image pickup device and said AGC circuit.

2. A video camera having an exposing apparatus, comprising:

a lens group for fetching a light from an object;

an iris for adjusting an amount of light from said lens group;

an image pickup device for converting the light which passed through said iris into an electric signal;

an AGC circuit for setting a signal level of an output signal from said image pickup device into a predetermined level;

a detecting circuit for detecting a luminance signal level from an output signal from said AGC circuit;

a reference level signal setting circuit for supplying an exposure control reference value;

an exposure control reference value modulating circuit for modulating said exposure control reference value, said exposure control reference value modulating circuit comprising;

a luminance level operating circuit to which a gain of said iris and a gain amount of said AGC circuit are supplied; and

an ROM having a reference level modulation coefficient according to a luminance level, and wherein an output signal of said ROM and an output signal from said reference level signal setting circuit are multiplied so as to form a modulation signal; and

control means for receiving said modulation signal and said luminance signal level and for producing a plurality of control signals therefrom, said control signals being respectively utilized to control said iris, said image pickup device and said AGC circuit.

3. A video camera having an exposing apparatus, comprising:

a lens group for fetching a light from an object;

an iris for adjusting an amount of light from said lens group;

an image pickup device for converting the light which passed through said iris into an electric signal;

an AGC circuit for setting a signal level of an output signal from said image pickup device into a predetermined level;

a detecting circuit for detecting a luminance signal level from an output signal from said AGC circuit;

a reference level signal setting circuit for setting an exposure control reference value to control the iris;

an exposure control reference value modulating circuit for modulating said exposure control reference value when the iris is controlled, said exposure control reference value modulating circuit comprising;

a luminance level operating circuit to which a gain of said iris and a gain amount of said AGC circuit are supplied;

a high luminance judging circuit to which an output signal of said luminance level operating circuit is input and into which a start luminance level and an end luminance level of the reference level modulation are set;

a modulation start/end setting circuit for setting the start luminance level and end luminance level of the modulation of said luminance signal;

a modulation coefficient calculating circuit to which a modulation coefficient calculation level is input on the basis of the set values of said start and end luminance levels; and

a modulation degree setting circuit for setting the maximum modulation degree of said modulation coefficient calculating circuit; and

a control circuit for receiving said luminance signal level and an output signal from said exposure control reference value modulating circuit and for producing control signals therefrom.

4. A video camera according to claim 3, further having a shutter driving circuit for controlling an image pickup timing of said image pickup device,

and wherein said control circuit controls said shutter driving circuit.

5. A video camera according to claim 4, wherein said control circuit controls each of said iris, said shutter driving circuit, and said AGC circuit.