Abstract: An image forming apparatus includes first and second rotatable members forming a nip therebetween, a heater disposed in inside of the second rotatable member, a first temperature sensor provided on a center of the heater, a second temperature sensor provided on an end side of the heater. A controller controls a feeding interval in which a trailing edge of a preceding sheet passes through the nip until a leading edge of a subsequent sheet reaches the nip. The controller controls the feeding interval to be a first interval in a case which a feeding speed of the sheet is a first speed and a detected temperature by the second sensor is a first temperature, and to be a second interval shorter than the first interval in a case which the feeding speed is a second speed lower than the first speed and the detected temperature is the first temperature.

Abstract: An image forming apparatus includes a fixing device having a heater, a first temperature detection unit, a pair of second temperature detection units, a pair of first sheet-width detection units, a pair of second sheet-width detection units, and a control unit. The heater includes a first heat generating element, a second heat generating element having a length smaller than a length of the first heat generating element in a longitudinal direction, and a third heat generating element having a length smaller than the length of the second heat generating element in the longitudinal direction. The control unit controls a temperature of the heater based on a detection result of the pair of first sheet-width detection units, a detection result of the pair of second sheet-width detection units, and a detection result of the pair of second temperature detection units.

Abstract: The heater including a substrate, a first heat generation member, a second heat generation member having a length substantially a same in a longitudinal direction as a length of the first heat generation member, a third heat generation member having a length shorter than lengths of the first heat generation member and the second heat generation member in the longitudinal direction, and a fourth heat generation member having a length shorter than length of the third heat generation member in the longitudinal direction, wherein the first heat generation member, the second heat generation member, the third heat generation member and the fourth heat generation member are arranged on the substrate.

Abstract: An image forming apparatus is operable in a first small-sheet printing in which power is supplied to the first heat generating element and the second heat generating element and in a second small-sheet printing in which power is supplied to the first heat generating element and the third heat generating element. A first power ratio, which is a proportion of power supplied to the first heat generating element to power supplied to the second heat generating element in the first small-sheet printing, is higher than a second power ratio, which is a proportion of power supplied to the first heat generating element to power supplied to the third heat generating element in the second small-sheet printing.

Abstract: A fixing unit includes a tubular film, a pressure roller, a heater including a first heating element and a second heating element, a detector configured to detect a temperature of the heater, a switcher configured to switch which of the first heating element and the second heating element is supplied power from a power supply, and a controller configured to control the switcher. The controller is configured to execute a first control of determining a first electric energy and a second electric energy based on the temperature of the heater detected by the detector and a target temperature of the heater, and a second control of causing the switcher to switch between a state in which power is supplied to the first heating element by the first electric energy and a state in which power is supplied to the second heating element by the second electric energy.

Abstract: An image forming apparatus includes a fixing unit including a tubular film, a pressure roller, and a heater including a heating element. The apparatus further includes a control unit configured to calculate an accumulated electrical energy supplied to a portion of the heating element. The portion of the heating element is located in an area corresponding to a second area of the nip portion. The second area is an area of the nip portion through which the recording material conveyed to the nip portion is not passed. The control unit is configured to determine an operation of heat leveling, which is performed for leveling a heat distribution in the nip portion after the recording material had passed the nip portion, based on the calculated accumulated electrical energy.

Abstract: The heater including a substrate, a first heat generation member, a second heat generation member having a length substantially a same in a longitudinal direction as a length of the first heat generation member, a third heat generation member having a length shorter than lengths of the first heat generation member and the second heat generation member in the longitudinal direction, and a fourth heat generation member having a length shorter than length of the third heat generation member in the longitudinal direction, wherein the first heat generation member, the second heat generation member, the third heat generation member and the fourth heat generation member are arranged on the substrate.

Abstract: A fixing apparatus including a heat generating element having a first area, a second area, and a third area, the first area being located on an end portion side in an orthogonal direction orthogonal to a conveyance direction of a recording material and having a first heat generation amount per unit length in the orthogonal direction, the second area being located on an inner side than the first area in the orthogonal direction and having a second heat generation amount per unit length in the orthogonal direction, the third area being located on the inner side than the second area in the orthogonal direction and having a third heat generation amount per unit length in the orthogonal direction. The second heat generation amount is larger than the third heat generation amount, and the third heat generation amount is larger than the first heat generation amount.

Abstract: A fixing apparatus including a heat generating element having a first area, a second area, and a third area, the first area being located on an end portion side in an orthogonal direction orthogonal to a conveyance direction of a recording material and having a first heat generation amount per unit length in the orthogonal direction, the second area being located on an inner side than the first area in the orthogonal direction and having a second heat generation amount per unit length in the orthogonal direction, the third area being located on the inner side than the second area in the orthogonal direction and having a third heat generation amount per unit length in the orthogonal direction. The second heat generation amount is larger than the third heat generation amount, and the third heat generation amount is larger than the first heat generation amount.

Abstract: In a case where fixing processing is performed continuously on sheets having a width that is shorter than a length of a heat generation member in a longitudinal direction and longer than a length of another heat generation member in the longitudinal directions, the CPU determines a timing to switch between the heat generation member and the another heat generation member by a heat generation member switching device based on information relating to a size of the sheet.

Abstract: An image forming apparatus includes a fixing device having a heater that includes a first heating element, a second heating element having a length smaller than the first heating element length, and a third heating element having a length smaller than the second heating element length. The image forming apparatus further includes a first temperature detection unit, a control unit, second temperature detection units, first and second sheet-width detection units, and a determination unit. The control unit controls a heater temperature based on the first temperature detection unit detection result. The determination unit determines a width of the recording material based on a detection result of the first sheet-width detection units, a detection result of the second sheet-width detection units, and a detection result of the second temperature detection units.

Abstract: A fixing apparatus including: a first rotary member; a second rotary member; a nip forming member; and a heater. The nip forming member includes: a first projection portion inside a nip area; and a second projection portion located outside the nip area. The first and second projection portion abut against the inner circumferential surface of the first rotary member. In a direction orthogonal to a nip tangent, a distance between a tip of the second projection portion and the nip tangent is larger than a distance between a tip of the first projection portion and the nip tangent. The second projection portion extends toward the second rotary member without exceeding the nip tangent. A radius of curvature at a tip portion of the second projection portion is smaller than a radius of an inner circumferential circle of the first rotary member.

Abstract: An image forming apparatus includes a fixing device having a heater that includes a first heating element, a second heating element having a length smaller than the first heating element length, and a third heating element having a length smaller than the second heating element length. The image forming apparatus further includes a first temperature detection unit, a control unit, second temperature detection units, first and second sheet-width detection units, and a determination unit. The control unit controls a heater temperature based on the first temperature detection unit detection result. The determination unit determines a width of the recording material based on a detection result of the first sheet-width detection units, a detection result of the second sheet-width detection units, and a detection result of the second temperature detection units.

Abstract: A heating apparatus to heat an image borne on a recording material includes a heater having a heater portion with first and second heating elements, where the heating elements have different lengths and resistance values. The heating apparatus also includes a power source, a switching unit, a control unit, and a voltage detection unit. The power source supplies power to the heating elements. The control unit controls the switching unit two switch a connection between the power source and the first heating element and the second heating element. The voltage detection unit detects an input voltage input from the power source to the heating elements. The control unit switches a power ratio, which is a ratio between an electric energy supplied from the power source to the first heating element and an electric energy supplied from the power source to the second heating element, depending on the detected input voltage.

Abstract: A fixing apparatus including: a first rotary member; a second rotary member; a nip forming member; and a heater. The nip forming member includes: a first projection portion inside a nip area; and a second projection portion located outside the nip area. The first and second projection portion abut against the inner circumferential surface of the first rotary member. In a direction orthogonal to a nip tangent, a distance between a tip of the second projection portion and the nip tangent is larger than a distance between a tip of the first projection portion and the nip tangent. The second projection portion extends toward the second rotary member without exceeding the nip tangent. A radius of curvature at a tip portion of the second projection portion is smaller than a radius of an inner circumferential circle of the first rotary member.

Abstract: An image forming apparatus is operable in a first small-sheet printing in which power is supplied to the first heat generating element and the second heat generating element and in a second small-sheet printing in which power is supplied to the first heat generating element and the third heat generating element. A first power ratio, which is a proportion of power supplied to the first heat generating element to power supplied to the second heat generating element in the first small-sheet printing, is higher than a second power ratio, which is a proportion of power supplied to the first heat generating element to power supplied to the third heat generating element in the second small-sheet printing.

Abstract: The heater including a substrate, a first heat generation member, a second heat generation member having a length substantially a same in a longitudinal direction as a length of the first heat generation member, a third heat generation member having a length shorter than lengths of the first heat generation member and the second heat generation member in the longitudinal direction, and a fourth heat generation member having a length shorter than length of the third heat generation member in the longitudinal direction, wherein the first heat generation member, the second heat generation member, the third heat generation member and the fourth heat generation member are arranged on the substrate.

Abstract: An image forming apparatus is operable in a first small-sheet printing mode in which power is supplied to a first heat generating element and a second heat generating element and in a second small-sheet printing mode in which power is supplied to the first heat generating element and a third heat generating element. A first power ratio, which is a proportion of power supplied to the first heat generating element to power supplied to the second heat generating element in the first small-sheet printing mode, is higher than a second power ratio, which is a proportion of power supplied to the first heat generating element to power supplied to the third heat generating element in the second small-sheet printing mode.

Abstract: The heater including a substrate, a first heat generation member, a second heat generation member having a length substantially a same in a longitudinal direction as a length of the first heat generation member, a third heat generation member having a length shorter than lengths of the first heat generation member and the second heat generation member in the longitudinal direction, and a fourth heat generation member having a length shorter than length of the third heat generation member in the longitudinal direction, wherein the first heat generation member, the second heat generation member, the third heat generation member and the fourth heat generation member are arranged on the substrate.

Abstract: An image forming apparatus comprises a plurality of sheet detection units, provided at different positions along a sheet width direction, configured to detect the sheet conveyed on a conveyance path. A controller determines, by using the plurality of sheet detection units, a presence or absence of a sheet being conveyed in each of a plurality of regions sectioned in the sheet width direction, and determines, based on input image data, a presence or absence of an image to be formed in each of the plurality of regions. The controller further determines, based on the above determination results, whether or not the image to be formed on the sheet being conveyed is to be formed with a deviation from the sheet, and controls an image forming operation in accordance with this determination result.