Abstract: A heater includes a substrate, a first electrical contact, a plurality of second electrical contacts, a plurality of electrode portions including first electrode portions electrically connected with the first electrical contact and second electrode portions electrically connected with the second electrical contacts, the first electrode portions and the second electrode portions being arranged alternately with predetermined gaps in a longitudinal direction of the substrate, and a plurality of heat generating portions provided between adjacent ones of the electrode portions so as to electrically connect between adjacent electrode portions, the heat generating portions being capable of generating heat by the electric power supply between adjacent electrode portions. A part of the second electrical contacts is selectably electrically connectable with the second terminal.

Abstract: In an image heating apparatus including heat generating members arranged along a longitudinal direction of a belt, when an image heating operation is performed on a recording material having a width which is smaller than a maximum width of the recording material usable in the image heating apparatus, the heat generating member positioned within an area corresponding to a non passing portion of the recording material is actuated together with the heat generating member positioned within an area corresponding to a non passing portion of the recording material.

Abstract: A heater includes: a substrate; a first electrical contact; second electrical contacts; first electrode portions and second electrode portions; heat generating portions; a first electroconductive line portion electrically connecting the first electrical contact and the first electrode portions; and a second electroconductive line portion electrically connecting one of the second electrical contacts and a part of the second electrode portions. A cross-sectional area of a portion, of the first electroconductive line portion, into which all of currents flowing through the first electrode portions merge when the currents flow from the first electrode portions toward the first electrical contact is larger than a cross-sectional area of a portion, of the second electroconductive line portion, into which all of currents flowing through the part of the second electrode portions merge when the currents flow from the part of the second electrode portions toward the one of second electrical contacts.

Abstract: A heater includes a substrate; a first electrical contact a plurality of second electrical contacts an electroconductive line portion electrically connected with the first electrical contact; a plurality of electrode portions including first electrode portions electrically connected with the first electrical contact through the electroconductive line portion and second electrode portions electrically connected with the second electrical contacts; and a plurality of heat generating portions provided between adjacent ones of the electrode portions. A cross-section of the electroconductive line portion in a side closer to the first electrical contact than the plurality of heat generating portions are with respect to the longitudinal direction is larger than a cross-section of a predetermined electrode portion, between adjacent heat generating portions, of the plurality of electrode portions.

Abstract: A fixing device includes a rotatable heating member and a rotatable pressing member which are configured to fix a toner image on a recording material in a nip therebetween; and a heating mechanism configured to selectively heat regions of the rotatable heating member depending on sizes of the recording material when the sizes are predetermined ones of all sizes usable in the fixing device. The rotatable pressing member includes a base layer and a porous elastic layer provided on the base layer and containing a needle-like filler. The elastic layer having a thermal conductivity, with respect to a longitudinal direction thereof, which is 6 times to 900 times a thermal conductivity with respect to a thickness direction thereof.

Abstract: An image heating apparatus includes an endless belt configured to heat an image on a sheet at a nip potion, a heat generation device configured to cause the belt to generate heat, a nip forming member configured to form the nip portion between the nip forming member and the belt, and a pressing roller configured to press an inner surface of the belt toward the nip forming member, the pressing roller including an elastic porous layer containing a plurality of filler particles, wherein a thermal conductivity of the elastic porous layer in an axial direction of the pressing roller is in a range of 6 times to 900 times a thermal conductivity of the elastic porous layer in a radial direction of the pressing roller.

Abstract: An image heating apparatus includes an endless belt configured to heat an image on a sheet at a nip potion, a heat generation device configured to cause the belt to generate heat, a nip forming member configured to form the nip portion between the nip forming member and the belt, and a pressing roller configured to press an inner surface of the belt toward the nip forming member, the pressing roller including an elastic porous layer containing a plurality of filler particles, wherein a thermal conductivity of the elastic porous layer in an axial direction of the pressing roller is in a range of 6 times to 900 times a thermal conductivity of the elastic porous layer in a radial direction of the pressing roller.

Abstract: In an image heating apparatus including heat generating members arranged along a longitudinal direction of a belt, when an image heating operation is performed on a recording material having a width which is smaller than a maximum width of the recording material usable in the image heating apparatus, the heat generating member positioned within an area corresponding to a non passing portion of the recording material is actuated together with the heat generating member positioned within an area corresponding to a non passing portion of the recording material.