Video endoscope system

• US 6,663,561 B2
• Filed: 10/03/2001
• Issued: 12/16/2003
• Est. Priority Date: 10/05/2000
• Status: Expired due to Fees

• Current Assignee: Pentax Corporation (Hoya Corporation)
• Original Assignee: Pentax Corporation (Hoya Corporation)
• Inventors: Sugimoto, Hideo, Enomoto, Takayuki, Ozawa, Ryo
• Primary Examiner(s): ROANE, AARON F
• Application Number:
  US09/968,917
• Publication Number:
  US 20020042556A1
• Time in Patent Office: 804 Days
• Field of Search: 600/160, 600/178, 600/181, 600/476, 600/478
• US Class Current: 600/160
• CPC Class Codes: A61B 1/043 for fluorescence imaging
• CPC Class Codes: A61B 1/0638 providing two or more wavelengths
• CPC Class Codes: A61B 1/0646 with illumination filters
• CPC Class Codes: A61B 1/0655 Control therefor
• CPC Class Codes: A61B 1/0669 at proximal end of an endoscope
• 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 23/74 by influencing the scene brightness using illuminating means

Abstract

A light transmitting part is formed on a second rotary shutter to intermittently transmit excitation light emitted from an excitation light source, which has a circumferential length substantially equal to a half of the entire periphery of the second rotary shutter in order to extend the period during which excitation light is emitted through a light distribution lens. As a living tissue is irradiated with excitation light, it generates autofluorescence. Although the autofluorescence is weak, a CCD can convert the image of the object under examination formed from the autofluorescence into a fluorescence video signal of a sufficient intensity level because excitation light is irradiated for an extended period of time. The obtained fluorescence video signal does not need to be amplified to an undesirable extent and hence can be processed with a high S/N to provide an appropriate diagnostic video signal that is free from noise.

Claims

1. A video endoscope system comprising:

an illuminating optical system that guides light to an object under examination;

a light source unit that emits visible light and excitation light for exciting a living tissue of the object to cause fluorescence, and that alternately transmits the visible light and the excitation light to said illuminating optical system so that a period during which the excitation light is transmitted to the illuminating optical system is longer than a period during which the visible light is transmitted to the illuminating optical system;

an objective optical system that converges optical components of light coming from a surface of the object, other than the excitation light, to form an image of the object;

an image pickup device that picks up the image of the object formed by said objective optical system and converts the image into a video signal; and

a processor that generates a reference video signal based on the video signal obtained by said image pickup device during the period when the visible light is transmitted to said illuminating optical system, and that generates a fluorescence video signal based on the video signal obtained by the image pickup device during the period when the excitation light is transmitted to said illuminating optical system, said processor generating a video signal to be used for diagnosis by subtracting the fluorescence video signal from the reference video signal.

2. The video endoscope system according to claim 1, wherein

said light source unit includes

a visible light source for emitting the visible light;

an excitation light source for emitting the excitation light; and

a light source switching device which alternately selects the visible light emitted from said visible light source and the excitation light emitted from said excitation light source to transmit to said illuminating optical system.

3. The video endoscope system according to claim 2, wherein

said light source switching device includes

a first shutter for intermittently blocking the visible light emitted from said visible light source in an optical path of the visible light;

a second shutter for intermittently blocking the excitation light emitted from said excitation light source in an optical path of the excitation light; and

a shutter drive mechanism which makes the second shutter block the excitation light while the first shutter transmits the visible light, and which makes the first shutter block the visible light while the second shutter transmits the excitation light.

4. The video endoscope system according to claim 3, wherein

said first shutter is a rotary shutter which is a disk blocking the visible light, formed with a visible light transmitting part for transmitting the visible light in an area along its circumference;

said second shutter is a rotary shutter which is a disk blocking the excitation light, formed with an excitation light transmitting part for transmitting the excitation light in an area along its circumference;

said shutter drive mechanism causes the first and second shutters to rotate so as to put the excitation light transmitting part of said second shutter into the optical path of the excitation light while said first shutter blocks the visible light, and to put the visible light transmitting part of said first shutter into the optical path of the visible light while said second shutter blocks the excitation light.

5. The video endoscope system according to claim 4, wherein

a central angle of said excitation light transmitting part relative to a center of rotation of said second shutter is greater than a central angle of said visible light transmitting part relative to a center of rotation of said first shutter;

and wherein said shutter drive mechanism rotates said first and second shutters at same angular velocity as each other.

6. The video endoscope system according to claim 1, further comprising

a monitor for displaying an image based on the video signal output from said processor.

7. A video endoscope system, comprising:

an illuminating optical system that guides light to an object under examination;

a light source unit that emits visible light and excitation light for exciting a living tissue of the object to cause fluorescence, said light source unit alternately transmitting the visible light and the excitation light to said illuminating optical system, a period during which said light source unit transmits the visible light to the illuminating optical system and a period during which said light source unit transmits the excitation light to the illuminating optical system being adjustable;

an objective optical system that converges optical components of light coming from a surface of the object, other than the excitation light, to form an image of the object;

an image pickup device that picks up the image of the object formed by said objective optical system and converts the image into a video signal; and

a processor that generates a reference video signal based on the video signal obtained by said image pickup device during the period when the visible light is transmitted to said illuminating optical system, and a fluorescence video signal based on the video signal obtained by the image pickup device during the period when the excitation light is transmitted to said illuminating optical system, said processor generating a video signal to be used for diagnosis by subtracting the fluorescence video signal from the reference video signal.

8. The video endoscope system according to claim 7, wherein the period during which the excitation light is transmitted to said illuminating optical system and the period during which the visible is transmitted to said illuminating optical are adjusted so that a ratio of an intensity of the reference video image signal, obtained during a period when a predetermined object is irradiated with the visible light, to an intensity of the fluorescence video signal, obtained during a period when the predetermined object is irradiated with the excitation light, is a predetermined value, the predetermined object reflecting the visible light with a predetermined reflectance when illuminated with the visible light and causing fluorescence when irradiated with the excitation light with an intensity in proportion to an intensity of the excitation light.

9. The video endoscope system according to claim 8, wherein

said light source unit includes

a visible light source for emitting the visible light;

an excitation light source for emitting the excitation light; and

a light source switching device which alternately selects the visible light emitted from said visible light source and the excitation light emitted from said excitation light source to transmit to said illuminating optical system and which can vary the period when the excitation light is transmitted to the illuminating optical system and the period when the visible light is transmitted to the illuminating optical system.

10. The video endoscope system according to claim 9, wherein

said processor has a controller which controls said light source switching device so as to adjust the period when the excitation light is transmitted to the illuminating optical system and the period when the visible light is transmitted to the illuminating optical system in those way.

11. The video endoscope system according to claim 10, wherein

said light source switching device includes

a first shutter for intermittently blocking the visible light emitted from said visible light source in an optical path of the visible light;

a second shutter for intermittently blocking the excitation light emitted from said excitation light source in an optical path of the excitation light; and

a shutter drive mechanism which makes the second shutter block the excitation light while the first shutter transmits the visible light, and which makes the first shutter block the visible light while the second shutter transmits the excitation light.

12. The video endoscope system according to claim 11, wherein

said first shutter includes a first rotary shutter and a second rotary shutter, each of the first and second rotary shutters comprising a disk for blocking the visible light and a visible light transmitting part for transmitting the visible light in an area along a circumference of the disk, said first and second rotary shutters rotating coaxially and together with each other;

said second shutter includes a third rotary shutter and a fourth rotary shutter, each of the third and fourth rotary shutters comprising a disk for blocking the excitation light and an excitation light transmitting part for transmitting the excitation light in an area along a circumference of the disk, said third and fourth rotary shutters rotating coaxially and together with each other; and

said shutter drive mechanism adjusts a peripheral length of a visible light transmitting area, which is an overlapping area of the visible light transmitting part of each of said first rotary shutter and said second rotary shutter, by changing relative phases of rotation between the first and second rotary shutters, and adjusts a peripheral length of an excitation light transmitting area, which is an overlapping area of the excitation light transmitting part of each of said third rotary shutter and said fourth rotary shutter, by changing relative phases of rotation between the third and fourth rotary shutters, said shutter drive mechanism rotating the respective rotary shutters such that the excitation light transmitting area of said third rotary shutter and said fourth rotary shutter is inserted into the optical path of the excitation light when said first rotary shutter and said second rotary shutter block the visible light, and that the visible light transmitting area of said first rotary shutter and said second rotary shutter is inserted into the optical path of the visible light when said third rotary shutter and said fourth rotary shutter block the excitation light.

13. The video endoscope system according to claim 7, further including

a monitor for displaying an image based on the video signal output from said processor.

14. A video endoscope system comprising:

an illuminating optical system that guides light to an object under examination;

a light source unit that emits visible light and excitation light for exciting a living tissue of the object to cause fluorescence, and that alternately transmits the visible light and the excitation light to said illuminating optical system so that a period during which the excitation light is transmitted to the illuminating optical system is longer than a period during which the visible light is transmitted to said illuminating optical system;

an objective optical system that converges optical components of light coming from a surface of the object, other than the excitation light, to form an image of the object;

an image pickup device that picks up the image of the object formed by said objective optical system and converts the image into a video signal; and

a processor that generates a reference video signal based on the video signal obtained by said image pickup device during the period when the visible light is transmitted to said illuminating optical system, and that generates a fluorescence video signal based on the video signal obtained by the image pickup device during the period when the excitation light is transmitted to said illuminating optical system;

said light source unit comprising;

a wheel that rotates around an axis parallel to a light path of the visible light, the wheel comprising a plurality of color filters positioned along a circumference of the wheel, the filters including a blue filter for transmitting only blue light, a green filter for transmitting only green light and a red filter for transmitting only red light; and

a wheel moving mechanism that moves the wheel between a first position, in which the plurality of color filters are sequentially inserted into the light path of the visible light between a light source switching device and said illuminating optical system as the wheel rotates, and a second position, in which the wheel is located out of the light path of the visible light,

said processor comprising a controller for controlling the light source switching device and the wheel moving mechanism;

said processor generating a diagnostic video signal by subtracting the fluorescence video signal from the reference video signal in a fluorescent observation mode, in which the controller controls the light source switching device to alternately select the visible light and the excitation light to transmit to said illuminating optical system, and controls the wheel moving mechanism to move the wheel to the second position; and

wherein said processor generates a plurality of color video signals, corresponding to the plurality of color filters, based on video signals obtained by said image pickup device during periods when the corresponding color filters are inserted into the light path of the visible light, and further generates an ordinary video signal representing a color image of the object under examination based on each of the color video signals in an ordinary observation mode, in which the controller controls the light source switching device to select only the visible light to transmit to said illuminating optical system and controls the wheel moving mechanism to move the wheel to the first position.

15. A video endoscope system comprising:

an illuminating optical system that guides light to an object under examination;

a light source unit that emits visible light and excitation light for exciting a living tissue of the object to cause fluorescence, and that alternately transmits the visible light and the excitation light to said illuminating optical system, a period during which the excitation light is transmitted to the illuminating optical system and a period during which the visible light is transmitted to said illuminating optical system being adjustable;

an objective optical system that converges optical components of light coming from a surface of the object, other than the excitation light, to form an image of the object;

an image pickup device that picks up the image of the object formed by said objective optical system and converts the image into a video signal; and

a processor that generates a reference video signal based on the video signal obtained by said image pickup device during the period when the visible light is transmitted to said illuminating optical system, and that generates a fluorescence video signal based on the video signal obtained by the image pickup device during the period when the excitation light is transmitted to said illuminating optical system;

said light source unit comprising;

a wheel comprising a plurality of color filters positioned along a circumference of the wheel, the filters including a blue filter for transmitting only blue light, a green filter for transmitting only green light and a red filter for transmitting only red light; and

a wheel driver that rotates the wheel and that moves the wheel between a first position, in which the plurality of color filters are sequentially and repeatedly inserted into an optical path of the visible light, and a second position, in which the wheel is retracted from the optical path of the visible light;

said processor setting said light source unit in one of a fluorescence observation state, in which the visible light and the excitation light are alternately transmitted to said illuminating optical system, and an ordinary observation state, in which only the visible light is transmitted to said illuminating optical system; and

wherein, when said light source unit is set in the fluorescence observation state, said processor controls the wheel driver to move the wheel to the second position and generates a video signal to be used for diagnosis by subtracting the fluorescence video signal from the reference video signal, and when said light source unit is set in the ordinary observation state, said processor controls the wheel driver to rotate the wheel and to move the wheel to the first position and generates a plurality of color video signals respectively based on signals obtained by said image pickup device during periods when the corresponding one of the plurality of color filters are inserted into the optical path of the visible light, said processor generating an ordinary video signal representing a color image of the object under examination based on the plurality of color video signals.