Variable focus camera for borescope or endoscope

• US 5,191,879 A
• Filed: 07/24/1991
• Issued: 03/09/1993
• Est. Priority Date: 07/24/1991
• Status: Expired due to Term

• Current Assignee: GE Inspection Technologies LP (General Electric Company)
• Original Assignee: Welch Allyn Incorporated
• Inventors: Krauter, Allan I.
• Primary Examiner(s): Millin, Vincent
• Assistant Examiner(s): Doyle, J.
• Application Number:
  US07/735,269
• Time in Patent Office: 594 Days
• Field of Search: 128/4, 359/823, 359/824, 359/826, 92/92, 138/120
• US Class Current: 600/109
• CPC Class Codes: A61B 1/00188 with focusing or zooming features
• CPC Class Codes: G02B 23/2484 Arrangements in relation to a camera or imaging device processing or control of video signals generated by an endoscope H04N23/60, H04N23/70

Abstract

A variable focus camera system for a borescope or endoscope has a camera or imager disposed within an imager sleeve and a braid and bladder assembly attached between the distal end of the imager sleeve and a lens assembly. A controlled pressure is applied through a pressure conduit into a confined volume defined by the imager sleeve, the braid and bladder assembly, and the lens assembly. The braid and bladder assembly expands axially but not radially, when pressure is applied, and changes the relative position of the imager and lens between a far focus and a near focus position.

Claims

1. A remotely focusing camera assembly for a borescope or endoscope of the type wherein an elongated insertion tube has a distal head which contains an imager, the insertion tube having an image-carrying cable extending proximally from the image within the insertion tube to a viewing device for displaying an image of an object in the field of view of the imager, the camera assembly comprising:

a tubular head sleeve at the distal head of said insertion tube,

a lens assembly including a focusing lens set and a tubular lens holder mounting same disposed at a distal end of the head sleeve;

an imager sleeve within the head sleeve, the imager sleeve containing the imager fixedly mounted therewithin;

with one of said lens assembly and said imager sleeve being fixedly mounted within the head sleeve, and the other thereof being axially slidable within said head sleeve;

means sealing the proximal end of said imager sleeve;

an elongatable braid and bladder assembly mounted onto a portion of said imager sleeve and said lens assembly such that the lens assembly, the braid and bladder assembly, the imager, the imager sleeve, and said sealing means define a confined volume, said bladder assembly including an elastomeric tube affixed at its one end over the imager sleeve and at its other end over said tubular lens holder of the lens assembly, and a braid disposed over said elastomeric tube and having substantially inelastic filaments oriented at an angle relative to the axis of the tube that substantially exceeds 54.7 degrees; and

means for applying a controlled pressure into said confined volume for controllably elongating said bladder assembly to move said imager sleeve relative to said lens assembly between a far-focus positioned and a near-focused position.

2. The camera assembly according to claim 1 wherein said imager sleeve is slidable within said head sleeve and includes an annular land for slidably contacting an inner wall of said head sleeve, and a sleeve relief of lesser outer diameter than said land projects distally therefrom.

3. The camera assembly according to claim 2 wherein said braid and bladder assembly further includes a proximal winding of a filament wrap binding said bladder assembly onto a proximal end of said sleeve relief.

4. The camera assembly according to claim 3 wherein said braid assembly further includes a distal winding of a filament wrap binding said bladder assembly onto said lens assembly.

5. The camera assembly according to claim 1 further comprising resilient biasing means disposed in said head sleeve between a proximal end of said imager sleeve and anchor means in the head sleeve to urge the imager sleeve distally towards its far-focus position.

6. The camera assembly according to claim 1 wherein said imager sleeve is fixedly mounted within said head sleeve and said lens assembly is slidably disposed within said head sleeve.

7. The camera assembly according to claim 6 wherein the head sleeve contains a distal optical window and a proximal wall that together form a confined volume containing said imager, said imager sleeve, said lens assembly, and said elongatable braid and bladder assembly.

8. The camera assembly according to claim 1 further comprising resilient means disposed in said head sleeve and coupled between said imager sleeve and said lens assembly for urging said lens assembly and said imager sleeve to the far-focus position when said controlled pressure is relieved.

9. The camera assembly according to claim 8 wherein said resilient means includes a compression spring for pushing said imager sleeve and said lens assembly to said far focus position.

10. A remotely focusing camera assembly for a borescope or endoscope which includes an insertion tube having a distal head that contains an imager, and an image-carrying cable extending proximally from the imager within the insertion tube to a viewing device for displaying an image of an object in the field of view of the imager, comprising:

a tubular head sleeve at the distal head of said insertion tube;

a lens assembly disposed at a distal end of the head sleeve;

an imager sleeve within the head sleeve, the imager sleeve containing the imager fixedly mounted therewithin;

with one of said lens assembly and said imager sleeve being fixedly mounted within the head sleeve, and the other thereof being axially slidable within said head sleeve;

means sealing the proximal end of said imager sleeve;

an elongatable braid and bladder assembly mounted onto a portion of said imager sleeve and said lens assembly such that the lens assembly, the braid and bladder assembly, the imager, the imager sleeve, and said sealing means define a confined volume, said bladder assembly including an elastomeric tube affixed at its ends to the imager sleeve and to the lens assembly, and a braid disposed over said elastomeric tube and having substantially inelastic filaments oriented at an angle relative to the axis of the tube that substantially exceeds 54.7 degrees; and

means for applying a controlled pressure into said confined volume for controllably elongating said bladder assembly to move said imager sleeve relative to said lens assembly between a far-focus position and a near-focus position;

wherein said imager sleeve is fixedly mounted within said head sleeve and said lens assembly is slidably disposed within said head sleeve, wherein the head sleeve contains a distal optical window and a proximal wall that together form a confined volume containing said imager, said imager sleeve, and said lens assembly, and said elongatable braid and bladder assembly, and wherein said image-carrying cable includes a sheathed image conduit extending from said imager proximally out of said imager sleeve and said head sleeve, and said conduit is provided with a vent in the region between the imager sleeve and the head sleeve.