Capsule endoscope and observation system that uses it

• US 20030158503A1
• Filed: 02/10/2003
• Published: 08/21/2003
• Est. Priority Date: 01/18/2002
• Status: Abandoned Application

• Current Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Original Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Inventors: Matsumoto, Shinya
• Application Number:
  US10/360,633
• Publication Number:
  US 20030158503A1
• Time in Patent Office: Days
• US Class Current: 600/593
• CPC Class Codes: A61B 1/00096 Optical elements
• CPC Class Codes: A61B 1/00181 for multiple fixed viewing angles A61B1/00193 takes precedence
• CPC Class Codes: A61B 1/041 Capsule endoscopes for imaging
• CPC Class Codes: A61B 1/0607 for annular illumination
• CPC Class Codes: A61B 1/273 for the upper alimentary canal, e.g. oesophagoscopes, gastroscopes
• CPC Class Codes: A61B 5/0031 Implanted circuitry

Abstract

A capsule endoscope body is provided with a spatial frequency characteristic converter which causes the optical transfer function of the imaging system of the capsule endoscope to remain essentially constant within some range of in-focus position. The depth of field of images obtained from the capsule endoscope body is increased by signal processing in order to undue the effects of the spatial frequency characteristic converter. Also, signal processing to reduce variations in image quality due to manufacturing tolerances can be provided within the capsule endoscope body. It is preferred, however, that the signal processing be performed within a receiver which is separate from the capsule endoscope body or, ideally, within a personal computer that receives image data signals from the receiver via cable or wireless communications, processes these image signals, and outputs corrected image signals to a display device.

Claims

1. A capsule endoscope body comprising the following components that are sealed within the capsule endoscope body:

an illumination system for illuminating an interior part of a living body;

an imaging system for imaging the interior part that is illuminated by the illumination system, said imaging system including

an objective optical system,

a spatial frequency characteristic converter which causes the optical transfer function of the imaging system to remain essentially constant within some range of in-focus position, and

an image sensor which scans the images so as to convert the images into electrical output signals; and

a transmitter for transmitting the signals output by the image sensor.

2. The capsule endoscope body according to claim 1, wherein the objective optical system consists of a single aspherical lens of positive refractive power.

3. The capsule endoscope body according to claim 1, wherein the objective optical system is formed of only two lens groups, each of positive refractive power.

4. The capsule endoscope body according to claim 1, wherein the objective optical system is formed of, in order from the object side, a first lens group having an overall negative refractive power, and a second lens group having an overall positive refractive power.

5. The capsule endoscope body according to claim 1, wherein the spatial frequency characteristic converter has an aperture which is shaped the same as the light receiving part of the image sensor.

6. The capsule endoscope body according to claim 1, wherein the image sensor is an MOS-type image sensor.

7. The capsule endoscope body according to claim 1, wherein power for operating the capsule endoscope body is provided by at least one battery located within the sealed capsule endoscope body.

8. The capsule endoscope body according to claim 1, wherein power for operating the capsule endoscope body is provided at least in part by the capsule endoscope body receiving electromagnetic energy from an energy source which is located outside the sealed capsule endoscope body.

9. The capsule endoscope body according to claim 1, wherein the objective optical system is formed of plastic lenses.

10. A capsule endoscope body according to claim 1, and further including within said capsule endoscope body a signal processing circuit for adjusting for manufacturing variations of the imaging system.

12. In combination:

a capsule endoscope body according to claim 1 and a capsule endoscope receiver for receiving image data transmitted from the capsule endoscope body, said image data having been modified by a spatial frequency characteristic converter which causes the optical transfer function of the imaging system to remain essentially constant within some range of in-focus position, said capsule endoscope receiver including a signal processor for restoring the spatial frequency content of the modified image data.

13. In combination:

a capsule endoscope body according to claim 10 and a capsule endoscope receiver for receiving image data transmitted from the capsule endoscope body.

14. The capsule endoscope body according to claim 1, wherein the sealed capsule has a transparent, substantially oval-shaped, tip portion cover that covers the front of the objective optical system and the illumination system.

15. The capsule endoscope body according to claim 1, wherein:

the sealed capsule has a transparent tip portion cover that covers the front of the objective optical system and the illumination system, with the shape of the tip portion cover at a part that covers the front of the objective optical system being different from the shape of the tip portion cover at a part that covers the front of the illumination system.

16. The capsule endoscope body according to claim 1, wherein the spatial frequency characteristic converter is positioned substantially at a pupil of the objective optical system.

17. The capsule endoscope body according to claim 1, wherein a frame for housing the objective optical system has an opening on the object side of the objective optical system which serves as a brightness stop, and the spatial frequency characteristic converter is positioned substantially at the brightness stop.

18. The capsule endoscope body according to claim 2, wherein a frame for housing the objective optical system has an opening on the object side of the objective optical system which serves as a brightness stop, and the spatial frequency characteristic converter is positioned substantially at the brightness stop.

19. The capsule endoscope body according to claim 3, wherein a frame for housing the objective optical system has an opening on the object side of the objective optical system which serves as a brightness stop, and the spatial frequency characteristic converter is positioned substantially at the brightness stop.

20. The capsule endoscope body according to claim 1, wherein said spatial frequency characteristic converter has a circular aperture.

21. The capsule endoscope body according to claim 1, wherein the imaging system further includes an additional objective optical system.

22. The capsule endoscope body according to claim 1, wherein said image sensor is a CCD.

23. In combination:

a capsule endoscope body according to claim 1, a capsule endoscope receiver for receiving image data transmitted from the capsule endoscope body, and an image data processing apparatus for processing the image data and displaying the image on a monitor, the image having been modified by a spatial frequency converter which causes the optical transfer function of the imaging system to remain essentially constant within some range of in-focus position, the image data processing apparatus including a signal processor for restoring the spatial frequency content of the modified image data.

11. A capsule endoscope receiver for receiving image data transmitted from a capsule endoscope body, said image data having been modified by a spatial frequency characteristic converter which causes the optical transfer function of an imaging system to remain essentially constant within some range of in-focus position, said capsule endoscope receiver including a signal processor for restoring the spatial frequency content of the modified image data.