Light source means for endoscope employing solid state imaging device

• US 4,625,236 A
• Filed: 07/17/1985
• Issued: 11/25/1986
• Est. Priority Date: 07/31/1984
• Status: Expired due to Term

• Current Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Original Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Inventors: Kato, Tadashi, Sasaki, Masahiko, Nagasaki, Tatsuo, Fujimori, Hiroyoshi
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US06/755,763
• Time in Patent Office: 496 Days
• Field of Search: 358/98, 358/42, 128/6
• US Class Current: 348/69
• CPC Class Codes: A61B 1/0638 providing two or more wavelengths
• CPC Class Codes: A61B 1/0646 with illumination filters
• CPC Class Codes: A61B 1/0669 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 source for an endoscope is disclosed for illuminating a subject, the image from the subject being received through a leading end of the endoscope, and being projected by an objective lens onto a solid state imaging device. Light from a light source lamp is projected onto the subject sequentially with the light transmitted through three color transmitting filters. A reflector is provided to reflect light from the light source lamp in a parallel light beam. A convex lens system for converging the parallel light from the reflector. Light from said source lamp is transmitted through a light guide to the subject. A first and second lens systems are positioned between the input end of the light guide and the convex lens system for converging the light onto the input end of the light guide. The light guide is disposed within an insert member of said endoscope. The lens systems reduce the sectional area of the light beam and restrict the included angle of the light beam. A rotary color filter is provided in said light beam and includes interference filters having high heat resistance for passing light of only a specific wavelength, to provide different colors of illuminating light to the subject.

Claims

1. An endoscope comprising:

an inserting member;

a focusing objective lens positioned at a leading end of said inserting member, said objective lens receiving light from a subject to be examined;

a solid state imaging device disposed in said inserting member such that an image plane of said imaging device is positioned at the focal plane of said objective lens;

a video process means receiving an output from said solid state imaging device for recording in a memory electrical signals from said imaging device corresponding to an image focussed on the image plane of said imaging device and outputting color signals therefrom;

display means connected to said video process means for displaying said color signals;

a light guide disposed within said inserting members for transmitting light therethrough, said light guide having an input end and an output end thereof, said output end positioned proximal to said objective lens for illuminating said subject;

a light source means for projecting light onto the input end of said light guide, said light source means providing sequential color illumination of three different colors to said light guide, including,

an illuminating source lamp,

a reflector, reflecting light from said source lamp in a parallel beam,

a convex lens system disposed in said parallel light path for converging said parallel light, to project said converging light onto said input end of said light guide,

a first lens system and a second lens system disposed in the optical path between said convex lens system and the input end of said light guide, said first lens system being positioned between said second lens system and said convex lens system, such that the cross sectional area of the light beam between said first and second lens systems is less than the cross sectional area of the parallel light beam between said reflector and said convex lens system, and such that said light beam between said first and second lens systems has a smaller angle with respect to the optical axis of said lens systems than the light between said convex lens system and said first lens system,

a rotary intereference color filter rotatably disposed in the light path between said first and second lens systems, said interference color filter having three different color filters therein such that each of the different color filters are sequentially positioned in the light path during rotation for passing light having specific wavelengths therethrough, and

driving means for rotating said rotary intereference color filter to sequentially illuminate the input end of the light guide, and in turn the subject with three colors of illuminating light.

2. The endoscope of claim 1, wherein said first lens system is concave and said second lens system is convex.

3. The endoscope of claim 1, wherein both said first and second lens system are convex.

4. The endoscope of claims 2 or 3, wherein an iris is disposed proximal to the focus point of the converging light to provide a small opening through which the focussed light may pass and to screen out unwanted light.

5. The endoscope of claim 1, further comprising an automatic light intensity conroller, including

an adder means connected to said video process means for generating a brightness signal by adding the input color signals from said video process means;

integrating means connected to said adder means for integrating said brightness signal for a predetermined time constant of approximately one frame period, and

a light source driver means for receiving said integrated brightness signal and producing a controlling signal and outputting same to said source lamp for controlling the intensity of illumination thereof.