Image pickup apparatus having auto-centering function

• US 6,933,977 B2
• Filed: 09/05/2001
• Issued: 08/23/2005
• Est. Priority Date: 05/25/2001
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Egashira, Yoshihiro
• Primary Examiner(s): Ho, Tuan
• Assistant Examiner(s): Ye, Lin
• Application Number:
  US09/945,660
• Publication Number:
  US 20040218060A1
• Time in Patent Office: 1,448 Days
• Field of Search: 348/335, 348/349, 348/333.12, 348/333.01, 348/222.1, 348/172, 348/65, 348/169, 348/170, 348/171, 348/208.99, 348/208.1, 348/219.1, 348/218.1, 348/74, 348/77, 600/117, 600/173, 600/118
• US Class Current: 348/333.12
• CPC Class Codes: H04N 23/555 for picking-up images in sites, inaccessible due to their dimensions or hazardous conditions, e.g. endoscopes or borescopes
• CPC Class Codes: H04N 5/2628 Alteration of picture size, shape, position or orientation, e.g. zooming, rotation, rolling, perspective, translation

Abstract

An address detector detects the position of boundary between an object image signal and other signal in an image output signal from an imaging device according to the difference in magnitude therebetween. A shift amount computation unit computes the shift amounts required to display the object at the center of a display screen according to the boundary position. A shift circuit shifts the phases of horizontal and vertical sync signals generated by a sync signal generator according to the shift amounts. A driving pulse generator generates driving pulses to drive the imaging device in response to the shifted horizontal and vertical sync signals. A sync adder adds the sync signals to the output signal of the imaging device and provides the resulting signal as a video output signal.

Claims

1. An image pickup apparatus which uses an imaging device for producing an imaging device output signal containing an object image signal representing an object image focused on its photosensitive surface which is larger than the object image and provides a video output signal corresponding to the object image, comprising:

a detector configured to detect the position of boundary between the object image signal and the other signal in the imaging device output signal in accordance with their difference in magnitude;

a shift amount computing unit configured to compute shift amounts that are required to display the object image on a display screen such that a center of an object image display area coincides with a center of the display screen, based on the boundary position detected by the detector;

a sync signal generator that generates horizontal and vertical sync signals to be added to the video output signal;

a shift circuit configured to shift phases of the horizontal and vertical sync signals generated by the sync signal generator based on the shift amounts computed by the shift amount computing unit;

a driving pulse generator that generates driving pulses to drive the imagine device, based on the horizontal and vertical sync signals shifted by the shift circuit; and

a sync adder configured to add the horizontal and vertical sync signals generated by the sync signal generator to the imaging device output signal to provide the video output signal.

2. The apparatus according to claim 1, wherein the image pickup apparatus is an endoscope.

3. The apparatus according to claim 1, wherein the shift amount computing unit:

(i) detects horizontal-direction minimum address HMIN of the object image signal, horizontal-direction maximum address HMAX of the object image signal, vertical-direction minimum address VMIN of the object image signal, and vertical-direction maximum address VMAX of the object image signal, and

(ii) computes a horizontal-direction shift amount Δ

tH and a vertical-direction shift amount Δ

tV according to formulas below;

Δ

tH=(H/2)−

(HMAX+HMIN)/2

Δ

tV=(V/2)−

(VMAX+VMIN)/2

where H is a horizontal-direction image size of the screen and V is a vertical-direction image size of the screen.

4. An image pickup apparatus which uses an imaging device for producing an imaging device output signal containing an object image signal representing an object image focused on its photosensitive surface which is larger than the object image and provides a video output signal corresponding to the object image, comprising

a detector configured to detect the position of boundary between the object image signal and the other signal in the imaging device output signal in accordance with their difference in magnitude;

a shift amount computing unit configured to compute shift amounts required to display the object image on a display screen such that a center of an object image display area coincides with a center of the display screen, based on the boundary position detected by the detector;

a sync signal generator that generates sync signals to be added to the video output signal;

a driving pulse generator that generates driving pulses to drive the imaging device, based on the sync signals generated by the sync signal generator;

a memory configured to store image data corresponding to the imaging device output signal from the imaging device;

a reading unit configured to read the image data from the memory while shifting the addresses of the memory in which one frame of image data has been written according to the shift amounts computed by the shift amount computation unit; and

a sync adder configured to add the sync signals generated by the sync signal generator to an image signal corresponding to the image data read out from the memory to provide the resulting signal as the video output signal.

5. An image pickup apparatus comprising:

an imaging device configured to produce an imaging device output signal containing an object image signal representing an image of an object focused on its photosensitive surface which is larger than the object image;

the a detector configured to detect the position of boundary between the object image signal and the other signal in the imaging device output signal in accordance with their difference in magnitude;

a shift amount computing unit responsive to the boundary position detected by the detector which computes shift amounts required to display the object image such that a center of an object image display area coincides with a center of the display screen;

a sync signal generator that generates horizontal and vertical sync signals to be added to the video output signal;

a shift circuit configured to shift the phases of horizontal and vertical sync signals generated by the sync signal generator based on the shift amounts computed by the shift amount computing unit;

a driving pulse generator that generates driving pulses to drive the imaging device, based on the horizontal and vertical sync signals shifted by the shift circuit; and

a sync adder adding the horizontal and vertical sync signals generated by the sync signal generator to the imaging device output signal to provide the video output signal.

6. The apparatus according to claim 5, further comprising a masking circuit masking noise in the blanking portions of the imaging device output signal.

7. An image pickup apparatus which uses an imaging device for producing an imaging device output signal containing an object image signal representing an object image focused on its photosensitive surface which is larger than the object image and provides a video output signal corresponding to the object image, comprising:

detecting means for detecting the position of boundary between the object image signal and the other signal in the imaging device output signal in accordance with their difference in magnitude;

shift amount computing means responsive to the boundary position detected by the detecting means for computing shift amounts required to display the object image on a display screen such that a center of an object image display area coincides with a center of the display screen;

sync signal generating means for generating sync signals to be added to the video output signal;

a shift circuit for shifting the phases of horizontal and vertical sync signals generated by the sync signal generating means in accordance with the shift amounts computed by the shift amount computing means;

driving pulse generating means for generating driving pulses to drive the imaging device, based on the horizontal and vertical sync signals shifted by the shift circuit; and

sync adding means for adding the sync signals generated by the sync signal generating means to the imaging device output signal to provide the video output signal.

8. The apparatus according to claim 7, further comprising masking circuit means for masking noise in the blanking portions of the imaging device output signal.

9. An image pickup apparatus which uses an imaging device for producing an imaging device output signal containing an object image signal representing an object image focused on its photosensitive surface which is larger than the object image and provides a video output signal corresponding to the object image comprising:

detecting means for detecting the position of boundary between the object image signal and the other signal in the imaging device output signal in accordance with their difference in magnitude;

shift amount computing means which computes shift amounts required to display the object image on a display screen such that a center of an object image display area coincides with a center of the display screen;

sync signal generating means for generating sync signals to be added to the video output signal;

driving pulse generating means for generating driving pulses to drive the imaging device, based on horizontal and vertical sync signals generated by the sync signal generating means; and

storage means for storing image data corresponding to the imaging device output signal from the imaging device;

read means for reading the image data from the storage means while shifting the addresses of the storage means in which one frame of image data has been written according to the shift amounts computed by the shift amount computation means; and

sync adding means for adding the sync signals generated by the sync signal generating means to an image signal corresponding to the image data read out from the storage means and providing the resulting signal as the video output signal.

10. The apparatus according to claim 9, further comprising a masking circuit masking noise in the blanking portions of the imaging device output signal.

11. A method for providing a video output signal corresponding to an image of an object using an imaging device for producing an imaging device output signal containing an object image signal representing the object image focused on its photosensitive surface which is larger than the object image comprising:

detecting the position of boundary between the object image signal and the other signal in the imaging device output signal in accordance with their difference in magnitude;

computing shift amounts required to display the object image on a display screen such that a center of an object image display area coincides with a center of the display screen according to the boundary position detected; and

generating horizontal and vertical sync signals for the video output signal;

shifting the phases of the horizontal and vertical sync signals in accordance with the shift amounts;

generating driving pulses to drive the imaging device, based on the shifted horizontal and vertical sync signals; and

adding the generated sync signals to the imaging device output signal to provide the video output signal.

12. The method according to claim 11, wherein said computing shift amounts comprises:

(i) detecting horizontal-direction minimum address HMIN of the object image signal, horizontal-direction maximum address HMAX of the object image signal, vertical-direction minimum address VMIN of the object image signal, and vertical-direction maximum address VMAX of the object image signal; and

(ii) computing a horizontal-direction shift amount Δ

tH and a vertical-direction shift amount Δ

tV according to formulas below;

Δ

tH=(H/2)−

(HMAX+HMIN)/2

Δ

tV=(V/2)−

(VMAX+VMIN)/2

where H is a horizontal-direction image size of the screen and V is a vertical-direction image size of the screen.

13. A method for providing a video output signal corresponding to an image of an object using an imaging device for producing an imaging device output signal containing an object image signal representing the object image focused on its photosensitive surface which is larger than the object image comprising:

detecting the position of boundary between the object image signal and the other signal in the imaging device output signal in accordance with their difference in magnitude;

computing shift amounts required to display the object image on a display screen such that a center of an object image display area coincides with a center of the display screen according to the boundary position detected;

generating horizontal and vertical sync signals for the video output signal;

generating driving pulses to drive the imaging device, based on the horizontal and vertical sync signals;

storing image data corresponding to the imaging device output signal from the imaging device in a memory;

reading the image data from the memory while shifting the addresses of the memory in which one frame of image data has been written according to the shift amounts computed; and

adding the horizontal and vertical sync signals to an image signal corresponding to the image data read out from the memory and providing the resulting signal as the video output signal.