Endoscope head, endoscope and albarran lever holding member

1. A housing sheath attachable to and detachable from an endoscope head body, which is provided on a distal side of an insertion portion of an endoscope, the housing sheath comprising:

a sheath that is a hollow cylinder open at an attachment opening provided along a longitudinal direction of the hollow cylinder, and is provided with a tool opening cut out in a U-shape at a location facing the attachment opening, the sheath comprising two hinges that are connected to both edges of the attachment opening and include engagement members configured to engage with each other, the hinges configured to detachably engage with the endoscope head body at an edge of the attachment opening; and

an Albarran lever that is rotatably supported inside the sheath.

2. The housing sheath according to claim 1 , wherein

the Albarran lever detachably engages with a pivot lever rotatably provided on the endoscope head body.

3. The housing sheath according claim 1 , further comprising

a housing sheath flat portion on an inner surface of the housing sheath at the location facing the attachment opening.

4. The housing sheath according to claim 3 , wherein

the housing sheath has a protrusion protruding from the housing sheath flat portion toward the attachment opening,

the Albarran lever has, at a proximal portion, an Albarran lever shaft rotatably supported by the protrusion, and

a tool pushing surface provided at an end portion of the Albarran lever moves toward the tool opening as the Albarran lever rotates about the Albarran lever shaft as an axis.

5. The housing sheath according to claim 1 , wherein

the endoscope includes a convex-shaped ultrasonic head that is disposed at an end portion of the endoscope head body and capable of transmitting and receiving ultrasonic signals in a lateral viewing direction, and

when attached to the endoscope head body, the Albarran lever is disposed inside an Albarran lever chamber, which is open continuously at the end portion and a side surface of the endoscope head body, and is rotatable with respect to the ultrasonic head.

6. The housing sheath according to claim 1 , wherein

the sheath forms a common assembly with the Albarran lever, wherein the common assembly of the housing sheath and the Albarran lever can be attached to and removed from the endoscope head body as one single unit.

7. The housing sheath according to claim 1 , wherein

the sheath is formed as a laterally open cylinder whose open side can be attached to the endoscope head body,

the Albarran lever pivotally supported in the sheath has an opening adapted to be able to engage in an operating element supported on the endoscope head body.

8. An ultrasonic endoscope comprising:

an endoscope head body that is disposed on a distal side of an insertion portion of the endoscope and is provided with an Albarran lever chamber which is open continuously at an end portion and a side surface of the endoscope head body;

a convex-shaped ultrasonic head that is disposed at the end portion of the endoscope head body and capable of transmitting and receiving ultrasonic signals in a lateral viewing direction corresponding to the side surface of the endoscope head body; and

a housing sheath including a hollow cylinder open at an attachment opening provided along a longitudinal direction of the hollow cylinder and rotatably supporting an Albarran lever inside, the housing sheath comprising two hinges that are connected to both edges of the attachment opening and include engagement members configured to engage with each other, the hinges being attachable to and detachable from the endoscope head body at an edge of the attachment opening, wherein

the Albarran lever chamber accommodates the Albarran lever when the housing sheath is attached.

9. The ultrasonic endoscope according to claim 8 , wherein

the endoscope head body has a flat portion that surrounds three sides of the Albarran lever chamber and extends along a longitudinal direction of the insertion portion.

10. The ultrasonic endoscope according to claim 9 , wherein

the endoscope head body has a wall extending from the flat portion on a proximal side of the Albarran lever chamber, said wall forming the proximal side of the Albarran lever chamber.

11. The ultrasonic endoscope according to claim 9 , wherein

when the housing sheath is attached, the flat portion abuts on a housing sheath flat portion provided on an inner surface of the housing sheath at a location facing the attachment opening.

12. The ultrasonic endoscope according to claim 8 , further comprising

a pin inside the Albarran lever chamber and rotatable with respect to the ultrasonic head, the pin having a rotating shaft,

wherein the pin detachably engages with the Albarran lever.

13. The ultrasonic endoscope according to claim 12 , wherein

the pin is fixed to a pivot lever that forms the rotating shaft and is rotatably supported by the endoscope head body, and

the pivot lever rotates in conjunction with an operation of an operation unit of the endoscope.