ELECTRONIC ENDOSCOPE

• US 20120253121A1
• Filed: 02/28/2012
• Published: 10/04/2012
• Est. Priority Date: 03/31/2011
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: KITANO, Ryou
• Granted Patent: US 8,602,979 B2
• Time in Patent Office: Days
• US Class Current: 600/109
• CPC Class Codes: A61B 1/00096 Optical elements
• CPC Class Codes: A61B 1/00177 for 90 degrees side-viewing
• CPC Class Codes: A61B 1/00181 for multiple fixed viewing angles A61B1/00193 takes precedence
• CPC Class Codes: A61B 1/00188 with focusing or zooming features
• CPC Class Codes: A61B 1/0623 for off-axis illumination

Abstract

A distal portion of an electronic endoscope is formed with a cutaway portion and a distal end surface. The distal portion is provided with side-viewing and front-viewing capturing optical systems. The side-viewing capturing optical system has a side-viewing objective lens, a prism with a half mirror surface, and a varifocal lens. Light incident on the half-mirror surface from the side-viewing objective lens is reflected to be incident on a CCD through the varifocal lens. Moving the varifocal lens allows the side-viewing capturing optical system to switch from normal observation to magnifying observation and vice versa. In the magnifying observation, a best focus position resides on an extension, of an outer circumferential surface of the distal portion, facing the cutaway portion.

Claims

1. An electronic endoscope having an insert section to be inserted into a subject, comprising:

a cutaway portion included in a distal portion of the insert section, the cutaway portion having a part of an outer circumferential surface of the distal portion cut away;

a side-viewing capturing optical system for forming an image of a target in a side-viewing direction through an image capture window provided to the cutaway portion, the side-viewing direction being orthogonal to an insertion direction of the insert section;

a side lighting optical system for applying illumination light to the target through a lighting window provided to the cutaway portion;

a focal length changer for changing a focal length of the side-viewing capturing optical system between a focal length for normal observation and a focal length for magnifying observation, a best focus position of the side-viewing capturing optical system in the magnifying observation resides on an extension of the outer circumferential surface, the extension facing the cutaway portion in the side-viewing direction; and

an image sensor for capturing the image formed by the side-viewing capturing optical system.

2. The electronic endoscope of claim 1, wherein the cutaway portion is formed with a first surface orthogonal to the side-viewing direction and a second surface surrounded by the outer circumferential surface and the first surface, and the second surface is inclined toward a front end side of the second surface.

3. The electronic endoscope of claim 2, wherein, the image capture window is formed on the first surface, and the lighting window is formed on the second surface.

4. The electronic endoscope of claim 3, wherein the side-viewing capturing optical system includes a side-viewing objective lens attached to the image capture window and an optical path changer for reflecting light from the side-viewing objective lens to the insertion direction so that the light is incident on the image sensor.

5. The electronic endoscope of claim 4, further including:

a distal end surface of the distal portion, the distal end surface being orthogonal to the insertion direction;

a front-viewing capturing optical system for forming an image of a target in a front-viewing direction, the front-viewing capturing optical system having a front-viewing objective lens provided on the distal end surface; and

a half mirror surface disposed at an intersection of an optical axis of the side-viewing objective lens and an optical axis of the front-viewing objective lens, the half mirror surface being the optical path changer, light from the front-viewing objective lens passing through the half mirror surface to be incident on the image sensor.

6. The electronic endoscope of claim 5, further including a front lighting optical system provided on the distal end surface, for illuminating the target observed with the front-viewing capturing optical system.

7. The electronic endoscope of claim 6, further including a switcher for passing light from one of the front-viewing capturing optical system and the side-viewing capturing optical system and blocking light from the other of the front-viewing capturing optical system and the side-viewing capturing optical system.

8. The electronic endoscope of claim 7, wherein the switcher is an LCD panel provided to each of the front-viewing capturing optical system and the side-viewing capturing optical system, and the LCD panel is switchable between a blocking state and a passing state, and the LCD panel blocks the light in the blocking state and passes the light in the passing state.

9. The electronic endoscope of claim 4, wherein the focal length changer is composed of a varifocal lens and a varifocal lens moving section for moving the varifocal lens along an optical axis direction.

10. The electronic endoscope of claim 9, wherein the varifocal lens is disposed between the optical path changer and the image sensor.

11. The electronic endoscope of claim 1, wherein the extension of the outer circumferential surface resides within a depth of field of the side-viewing capturing optical system in the normal observation.