PHOTOGRAPHING APPARATUS

• US 20100214439A1
• Filed: 07/25/2008
• Published: 08/26/2010
• Est. Priority Date: 07/26/2007
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Fuchigami, Ikuo, Toma, Tadamasa, Tezuka, Tadanori, Oshima, Mitsuaki
• Granted Patent: US 8,451,372 B2
• Time in Patent Office: Days
• US Class Current: 348/229.100
• CPC Class Codes: G03B 7/087 for control of both exposure time and aperture
• CPC Class Codes: H04N 2101/00 Still video cameras
• CPC Class Codes: H04N 23/633 for displaying additional information relating to control or operation of the camera
• CPC Class Codes: H04N 23/667 Camera operation mode switching, e.g. between still and video, sport and normal or high- and low-resolution modes
• CPC Class Codes: H04N 23/75 by influencing optical camera components

Abstract

When shooting an image at a normal frame rate, and continuing to shoot the image by changing the frame rate to a high-speed frame rate, the image shooting apparatus of the present invention, before the frame rate is actually changed, causes the aperture to transit to a value which ensure that the amount of exposure before the change of the frame rate is ensured after the change, in correspondence with the exposure time that can be ensured during the high-speed shooting, and causes the exposure time to transit to the exposure time that can be ensured during the high-speed shooting, so that the frame rate is changed quickly and the image is reproduced smoothly when a portion corresponding to the frame rate change is reproduced.

Claims

1. An image shooting apparatus comprising:

an imaging unit operable to read out signals from an image sensor and output image frames in sequence at a predetermined frame rate, the image sensor collecting charges through a photoelectric conversion of incident light;

a frame rate changing unit operable to change a frame rate while the imaging unit outputs the image frames in sequence;

an aperture adjusting unit operable to adjust a level of aperture that determines an amount of the incident light;

an exposure time adjusting unit operable to adjust an exposure time that is a time taken for collecting the charges through the photoelectric conversion of the incident light;

a determining unit operable to determine a post-change aperture level so that a post-change amount is substantially equal to a pre-change amount, the post-change amount being an amount of collected charges corresponding to each frame of image shot at a post-change frame rate, the pre-change amount being an amount of collected charges corresponding to each frame of image shot at a pre-change frame rate, where the frame rate changing unit changes the frame rate from the pre-change frame rate to the post-change frame rate; and

a control unit operable, before the change of the frame rate, to control the aperture adjusting unit to adjust the level of aperture to transit to the post-change aperture level determined by the determining unit, and to control the exposure time adjusting unit to adjust the exposure time in accordance with the level of aperture in transition so that the post-change amount of collected charges is, substantially equal to the pre-change amount of collected charges.

2. The image shooting apparatus of claim 1 further comprising

an instruction obtaining unit operable to obtain from outside an instruction for changing the frame rate while the image frames are output by the imaging unit in sequence,

the determining unit determines the post-change aperture level when the instruction obtaining unit obtains the instruction for changing the frame rate, and

when the instruction obtaining unit obtains the instruction, the control unit, before the change of the frame rate, controls the aperture adjusting unit and the exposure time adjusting unit to start adjusting respectively the level of aperture and the exposure time.

3. The image shooting apparatus of claim 1, wherein

the determining unit further determines a post-change exposure time in accordance with the post-change frame rate, and when having determined the post-change exposure time to be “

1/a”

times the exposure time, before the change, determines the post-change aperture level so that an area of opening of an aperture becomes substantially “

a”

times thereof, and

the control unit controls the exposure time adjusting unit to adjust the exposure time to transit to the post-change exposure time determined by the determining unit.

4. The image shooting apparatus of claim 1, wherein

after the frame rate changing unit returns the frame rate from the post-change frame rate to the pre-change frame rate, the control unit controls the aperture adjusting unit to adjust the level of aperture to transit from the post-change aperture level to an aperture level before the change, and controls the exposure time adjusting unit to adjust the exposure time in accordance with the level of aperture in transition so that an amount of collected charges for each image frame after the return of the frame rate is substantially equal to an amount of collected charges for each image frame before the return.

5. The image shooting apparatus of claim 1, wherein

the post-change frame rate is higher than the pre-change frame rate,

the image shooting apparatus further comprises:

a recording instruction obtaining unit operable to obtain an instruction for recording;

a conversion unit operable to convert from an image frame output at the post-change frame rate to an image frame output at the pre-change frame rate;

a storage unit storing the image frames output from the imaging unit, wherein, when the recording instruction obtaining unit obtain the instruction for recording after the frame rate changing unit changes the frame rate, the storage unit stores a predetermined number of images frames before and after the receiving of the recording instruction, and images frames other than the images frames before and after the receiving of the recording instruction are converted by the conversion unit and results of the conversion are stored in the storage unit.

6. An image shooting apparatus comprising:

an imaging unit operable to read out signals from an image sensor and output image frames in sequence at a predetermined frame rate, the image sensor collecting charges through a photoelectric conversion of incident light;

a frame rate changing unit operable to change a frame rate while the imaging unit outputs the image frames in sequence;

an aperture adjusting unit operable to adjust a level of aperture that determines an amount of the incident light;

an exposure time adjusting unit operable to adjust an exposure time that is a time taken for collecting the charges through the photoelectric conversion of the incident light;

a determining unit operable to determine a post-change aperture level so that a post-change amount is substantially equal to a pre-change amount, the post-change amount being an amount of collected charges per frame of image shot at a post-change frame rate, the pre-change amount being an amount of collected charges corresponding to each frame of image shot at a pre-change frame rate, where the frame rate changing unit changes the frame rate from the pre-change frame rate to the post-change frame rate; and

a control unit operable, after the change of the frame rate, to control the aperture adjusting unit to adjust the level of aperture to transit to the post-change aperture level determined by the determining unit.

7. An integrated circuit for use in an image shooting apparatus, the integrated circuit comprising:

an imaging unit operable to read out signals from an image sensor and output image frames in sequence at a predetermined frame rate, the image sensor collecting charges through a photoelectric conversion of incident light;

a frame rate changing unit operable to change a frame rate while the imaging unit outputs the image frames in sequence;

an aperture adjusting unit operable to adjust a level of aperture that determines an amount of the incident light;

an exposure time adjusting unit operable to adjust an exposure time that is a time taken for collecting the charges through the photoelectric conversion of the incident light;

a determining unit operable to determine a post-change aperture level so that a post-change amount is substantially equal to a pre-change amount, the post-change amount being an amount of collected charges corresponding to each frame of image shot at a post-change frame rate, the pre-change amount being an amount of collected charges corresponding to each frame of image shot at a pre-change frame rate, where the frame rate changing unit changes the frame rate from the pre-change frame rate to the post-change frame rate; and

a control unit operable, before the change of the frame rate, to control the aperture adjusting unit to adjust the level of aperture to transit to the post-change aperture level determined by the determining unit, and to control the exposure time adjusting unit to adjust the exposure time in accordance with the level of aperture in transition so that the post-change amount of collected charges is substantially equal to the pre-change amount of collected charges.

8. An image shooting method f or use in an image shooting apparatus, the image shooting method comprising the steps of:

reading out signals from an image sensor and outputting image frames in sequence at a predetermined frame rate, the image sensor collecting charges through a photoelectric conversion of incident light;

changing a frame rate while the image frame outputting step outputs the image frames in sequence;

adjusting a level of aperture that determines an amount of the incident light;

adjusting an exposure time that is a time taken for collecting the charges through the photoelectric conversion of the incident light;

determining a post-change aperture level so that a post-change amount is substantially equal to a pre-change amount, the post-change amount being an amount of collected charges corresponding to each frame of image shot at a post-change frame rate, the pre-change amount being an amount of collected charges corresponding to each frame of image shot at a pre-change frame rate, where the frame rate changing step changes the frame rate from the pre-change frame rate to the post-change frame rate; and

before the change of the frame rate, controlling the aperture adjusting step to adjust the level of aperture to transit to the post-change aperture level determined by the determining step, and controlling the exposure time adjusting step to adjust the exposure time in accordance with the level of aperture in transition so that the post-change amount of collected charges is substantially equal to the pre-change amount of collected charges.