Patent application number | Description | Published |
20090175644 | IMAGE FORMING APPARATUS - An image forming apparatus has an image forming station and a fixing unit. The fixing unit includes a coil for generating a magnetic field for induction heating the heating member. A first core made of a magnetic material is arranged fixedly around the coil. A second core made of a magnetic material is between the first core and the heating member in a generation direction of the magnetic field to form a magnetic path in cooperation with the first core and capable of changing a posture thereof. A shield made of a nonmagnetic metal is arranged along the outer surface of the second core to shield magnetism in the magnetic field and a magnetic shielding portion for changing the posture of the second core between a first posture where the shield shields the magnetism and a second posture where the shield does not shield the magnetism. | 07-09-2009 |
20090175664 | IMAGE FORMING APPARATUS - A fixing unit ( | 07-09-2009 |
20090245898 | IMAGE FORMING APPARATUS - An image forming apparatus includes a fixing unit fixing a toner image onto a sheet. The fixing unit includes a heating member having a sheet conveyed region that is set in accordance with the size of the sheet. The fixing unit further includes a coil generating magnetic field, a fixed core forming a magnetic path, movable cores forming a magnetic path together with the fixed core and arranged along the sheet conveyed region, a shielding member arranged on at least one movable core and shielding magnetism, and a magnetism adjustment unit rotating at least one movable core to switch the position of the shielding member between a shielding position where the shielding member is positioned inside the sheet conveyed region to shield the magnetism and a retracted position where the shielding member is positioned outside the sheet conveyed region to permit pass of the magnetism. | 10-01-2009 |
20090245902 | IMAGE FORMING APPARATUS - An image forming apparatus is provided with an image forming station and a fixing unit including a heating member. The fixing unit includes a coil for generating a magnetic field for induction heating the heating member; a first core arranged to face the heating member with the coil located therebetween; a bar-shaped second core including a cut-off portion and arranged in a magnetic path between the first core and the heating member, when seen in a magnetic field generation direction by the coil, to form the magnetic path together with the first core; and a magnetic adjusting mechanism for changing the posture of the second core between a first posture for guiding a magnetic field by retracting the cut-off portion from the magnetic path and a second posture for increasing magnetic resistance by locating the cut-off portion in the magnetic path by rotating the second core about an axis thereof. | 10-01-2009 |
20090269109 | IMAGE FORMING APPARATUS - An image forming apparatus includes an image forming unit and a fixing unit. The fixing unit includes a heating member; a coil arranged along an outer surface of the heating member for generating a magnetic field for induction heating the heating member; a core arranged to face the heating member with the coil located therebetween in order to form a magnetic path around the coil and made of a magnetic material; a shielding member arranged near the magnetic path generated by the coil, including a closed frame portion and made of a nonmagnetic metal; and a magnetic shielding portion for displacing the shielding member between a retracted position for permitting a magnetic flux to pass along a frame surface virtually formed inside the closed frame portion and a shielding position for shielding magnetism by the penetration of a magnetic flux inside the frame surface. | 10-29-2009 |
20100014900 | IMAGE FORMING APPARATUS - A fixing unit of an image forming apparatus includes a magnetism adjusting unit switching the position of a shielding member between a shielding position where the shielding member is positioned inside the sheet-conveyed region to shield the pass of the magnetism and a retracted position where the shielding member is positioned outside the sheet-conveyed region to permit the pass of the magnetism. The shielding member is provided in a plural number in the axial direction of the movable core. The shielding members have a different length in the axial direction and a different width in a circumferential direction of the movable core, the length and the width corresponding to a plurality of sizes of the sheet in the width direction of the sheet. The magnetism adjusting unit switches each of the shielding members between the shielding position and the retracted position in accordance with the width-direction size of the sheet. | 01-21-2010 |
20100046996 | FIXING UNIT AND IMAGE FORMING APPARATUS COMPRISING FIXING UNIT - A fixing unit for fixing a toner image onto paper has a member to be heated and a pressurizing member configured to press against the member to be heated and fix the toner image to the paper. At least one coil surface is disposed along one surface of the member to be heated and includes a coil to generate a magnetic field for inductively heating the member. A magnetism shielding member is disposed near the coil surface. A switch includes a first member to allow passage of the magnetic field and a second member to prevent passage of the magnetic field. The amount of heat for the member when the switch is in a first position where the second member is close to the magnetism shielding member is smaller than when the switch is in a second position where the second member is distanced from the magnetism shielding member. | 02-25-2010 |
20110052281 | FIXING UNIT AND IMAGE FORMING APPARATUS WITH THE SAME - A fixing unit for fixing a toner image onto a sheet passing between a first element and a second element pressed against the first element includes a looped coil surface formed with a coil so that the coil surface generates a magnetic field for induction-heating the first element, the coil surface including an inner edge defining an opening region; an upright wall disposed inside the opening region, an opening being formed in the upright wall; a center core disposed along the opening region, the center core including a conductive shaft and a magnetic tube configured to at least partially cover the conductive shaft; and a nonconductive cap inserted into the opening, the nonconductive cap partially covering the conductive shaft to electrically insulate the coil from the conductive shaft. | 03-03-2011 |
20120057909 | ELECTROMAGNETIC INDUCTION HEATING FIXING APPARATUS AND IMAGE FORMING APPARATUS HAVING THE SAME - A fixing apparatus includes: a magnetic flux generating source which generates a magnetic flux; an endless belt which inductively generates heat by the magnetic flux while rotating in a prescribed direction; a rotating body which rotates in a prescribed direction and, together with the belt, forms a nip section through which a recording medium carrying a toner image passes; a core which is made of a magnetic material, and directs the magnetic flux to the belt; a heat value adjustment member for adjusting an amount of heat generated in the belt; and a gripping piece which is a non-rotating member, is disposed in a position corresponding to the nip section, and contacts an inner surface of the belt to rotatably grip the belt against the rotating body. The belt is wrapped between the heat value adjustment member and the gripping piece. | 03-08-2012 |