Image pickup device

• US 6,630,960 B2
• Filed: 05/13/1998
• Issued: 10/07/2003
• Est. Priority Date: 08/21/1991
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Tsuda, Yuji, Takahashi, Koji, Kyuma, Kenji, Tamura, Kyoji
• Primary Examiner(s): Vu, Ngoc-Yen, VU, NGOC YEN T
• Application Number:
  US09/078,077
• Publication Number:
  US 20020080247A1
• Time in Patent Office: 1,973 Days
• Field of Search: H04/N.5235, H04/N.5238, 348/207, 348/222, 348/229, 348/296, 348/234-238, 348/362-366, 348/221.1, 348/222.1, 348/224.1, 348/229.1, 348/230.1, 348/254, 348/255, 396/96, 396/213, 396/233, 396/234
• US Class Current: 348/364
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation
• CPC Class Codes: H04N 23/72 Combination of two or more compensation controls
• CPC Class Codes: H04N 23/745 Detection of flicker frequency or suppression of flicker wherein the flicker is caused by illumination, e.g. due to fluorescent tube illumination or pulsed LED illumination

Abstract

An image pickup device capable of exposure control utilizing the iris aperture, shutter speed and gain as three control parameters, comprising means for setting a photometry area in the image frame; means for setting an input parameter as a reference for evaluation, based on the luminance information in an image signal obtained from the photometry means; means for determining the values of the three control parameters for exposure control, according to the value of the input parameter; switch means for switching, according to the phototaking mode, a program setting the control caharacteristics of each control parameter as a function of the input parameter; and photometry area switch means for switching the set state of the photometry area in the image frame, in linkage with the switching operation of the switch means, wherein the phototaking mode is switched according to the phototaking conditions, thereby controlling the parameters and the light metering area according to a program matching the phototaking mode, and enabling to constantly effect the optimum phototaking operation under any phototaking situation or conditions.

Claims

1. An image pickup device apparatus comprising:

exposure control means for controlling exposure by operating an input brightness level obtained by weighing brightness levels of a plurality of blocks divided into an image pickup plane, and comparing the operated input brightness level with a predetermined evaluation reference value; and

photographing mode selection means for selecting one of a plurality of photographing modes which are preset in said image pickup apparatus,

wherein said exposure control means is adapted to change the evaluation reference value according to the photographing mode selected by said photographing mode selection means, and said exposure control means is adapted to select a predetermined number of blocks whose brightness levels are larger than the evaluation reference value, in order of a magnitude of the brightness level from a maximum level, by weighting the plurality of blocks in case that an object is a high brightness object.

2. An apparatus according to claim 1, wherein said photographing modes include a photographing mode suitable for photographing a high brightness and high contrast object.

3. An apparatus according to claim 1, wherein said exposure control means adjusts at least one of an accumulation time of an image sensor, an aperture of an iris and a gain of AGC.

4. An apparatus according to claim 1, wherein each of control parameters for controlling an accumulation time of an image sensor, an aperture of an iris and a gain of AGC is divided into plural variable ranges according to the value of said input brightness level.

5. An image pickup device apparatus comprising:

exposure control means for controlling an exposure by operating input brightness levels in a plurality of blocks divided into an image pickup plane, and comparing the operated input brightness levels with an evaluation reference value; and

mode selection means for selecting one of a plurality of photographing modes which are preset in said image pickup apparatus and presetting an exposure control mode corresponding to the selected photographing mode,

wherein said exposure control means is adapted to change the evaluation reference value according to the exposure control mode corresponding to the photographing mode selected by said mode selection means and is adapted to select blocks whose brightness levels are larger than the evaluation reference value and position in a predetermined high brightness range from a maximum level, by weighting the plurality of blocks in case that an object is a high brightness object.

6. An apparatus according to claim 5, wherein said exposure control modes include an exposure control mode suitable for photographing a high brightness and high contrast object in a field.

7. An apparatus according to claim 5, wherein said exposure control means adjusts at least one of an accumulation time of an image sensor, an aperture of an iris and a gain of AGC, and control parameters are stored as a function of an input brightness level in a memory.

8. An apparatus according to claim 5, wherein each of control parameters for controlling an accumulation time of an image sensor, an aperture of an iris and a gain of AGC is divided into plurality variable ranges according to the value of an input brightness level.

9. An exposure control method comprising:

an exposure control step controlling an exposure state by operating input brightness levels in a plurality of blocks divided into an image pickup plane, and comparing the operated input brightness levels with an evaluation reference value; and

a mode selection step of selecting one of a plurality of photographing modes and presetting an exposure control mode corresponding to the selected photographing mode,

wherein said exposure control step is adapted to change the evaluation reference value according to the exposure control mode corresponding to the photographing mode selected in said mode selection step and is adapted to select blocks whose brightness levels are larger than the evaluation reference value and position in a predetermined high brightness range from a maximum level, by weighting the plurality of blocks in case that an object is a high brightness object.

10. A method according to claim 9, wherein said exposure control modes include an exposure control mode suitable for photographing a high brightness and high contrast object in a field.

11. A method according to claim 9, wherein said exposure control step adjusts at least one of an accumulation time of an image sensor, an aperture of an iris and a gain of AGC, and control parameters are stored as a function of an input brightness level in a memory.

12. A method according to claim 9, wherein each of control parameters for controlling an accumulation time of an image sensor, an aperture of an iris and a gain of AGC is divided into plural variable ranges according to the value of an input brightness level.