Optical unit, image pickup apparatus, endoscope, and method for moving lens of optical unit

An image pickup apparatus mounted on a distal end portion of an insertion portion of an endoscope, the image pickup apparatus comprising:

• an optical unit comprising:
• a moving barrel made of a magnetic body and configured to hold an optical element that constitutes a lens unit to form an object image;
• a fixed barrel made of a nonmagnetic body and configured to accommodate the moving barrel so as to freely move back and forth in a direction along an optical axis of the lens unit;
• a bias member configured to bias the moving barrel in a first direction along the optical axis;
• a magnet disposed on an outer circumferential surface of the fixed barrel and configured to attract the moving barrel in a second direction opposite to the first direction along the optical axis by a magnetic force;
• and
• a coil wound around the outer circumferential surface of the fixed barrel and configured to make variable the magnetic force given to the moving barrel by a magnetic field generated through current application;
• and
• an image pickup device configured to receive and photoelectrically convert light focused by the optical element.

An endoscope comprising:

• an insertion portion;
• and
• an image pickup apparatus mounted on a distal end portion of the insertion portion, the image pickup apparatus including an optical unit,
• the optical unit including:
• a moving barrel made of a magnetic body and configured to hold an optical element that constitutes a lens unit to form an object image,
• a fixed barrel made of a nonmagnetic body and configured to accommodate the moving barrel so as to freely move back and forth in a direction along an optical axis of the lens unit,
• a bias member configured to bias the moving barrel in a first direction along the optical axis,
• a magnet disposed on an outer circumferential surface of the fixed barrel and configured to attract the moving barrel in a second direction opposite to the first direction along the optical axis by a magnetic force, and
• a coil wound around the outer circumferential surface of the fixed barrel and configured to make variable the magnetic force given to the moving barrel by a magnetic field generated through current application;
• and
• an image pickup device configured to receive and photoelectrically convert light focused by the optical element.

A method for moving a lens of an optical unit mounted on a distal end portion of an insertion portion of an endoscope, the optical unit including

• a moving barrel made of a magnetic body and configured to hold an optical element that constitutes a lens unit to form an object image;
• a fixed barrel made of a nonmagnetic body and configured to accommodate the moving barrel so as to freely move back and forth in a direction along an optical axis of the lens unit;
• a bias member configured to bias the moving barrel in a first direction along the optical axis;
• a magnet disposed on an outer circumferential surface of the fixed barrel and configured to attract the moving barrel in a second direction opposite to the first direction along the optical axis by a magnetic force;
• and
• a coil wound around the outer circumferential surface of the fixed barrel and configured to make variable the magnetic force given to the moving barrel by a magnetic field generated through current application,
• the method comprising:
• moving the moving barrel in the first direction by the bias member and moving the moving barrel in the second direction by current application to the coil.