Thermal fixing device that avoids overheating and image forming device having the thermal fixing device

Claim 2

A thermal fixing device, comprising: a roller; a heater that heats the roller; a temperature sensor to sense a temperature of the roller; and a thermal cutoff device to interrupt power supply to the heater based on the temperature of the roller, wherein the heater has a temperature distribution that is symmetrical in an axial direction of the roller with respect to a temperature distribution center, and the temperature sensor and the thermal cutoff device are disposed facing a surface of the roller in alignment with symmetrical positions spaced by a predetermined distance, in the axial direction of the roller from the temperature distribution center.

Claim 3

The thermal fixing device according to claim 1 , wherein a plurality of thermal cutoff devices are provided as the thermal cutoff device.

Claim 4

The thermal fixing device according to claim 1 , wherein at least one of the temperature sensor and the thermal cutoff device is disposed on a plane including an axis of the roller.

Claim 5

The thermal fixing device according to claim 1 , wherein the thermal cutoff device has a temperature sensing element that senses a temperature, and the temperature sensing element is disposed facing the surface of the roller in alignment with a position spaced by a predetermined distance, in the axial direction of the roller from the temperature distribution center.

Claim 6

The thermal fixing device according to claim 1 , wherein different types of thermal cutoff devices are provided as the thermal cutoff device.

Claim 7

The thermal fixing device according to claim 1 , wherein the temperature sensor is adjacent to a thermostat.

Claim 8

The thermal fixing device according to claim 1 , wherein the temperature sensor is provided proximate the roller.

Claim 9

The thermal fixing device according to claim 1 , wherein the thermal cutoff device is provided proximate the roller.

Claim 10

The thermal fixing device according to claim 2 , wherein the plurality of thermal cutoff devices are disposed on a circumference about an axis of the roller in alignment with positions identical in temperature in the temperature distribution.

Claim 11

The thermal fixing device according to claim 2 , wherein the temperature sensor and at least one of the plurality of thermal cutoff devices are disposed on the same plane including an axis of the roller.

Claim 12

The thermal fixing device according to claim 2 , wherein each of the plurality of thermal cutoff devices has a temperature sensing element that senses a temperature, and each temperature sensing element is disposed facing the surface of the roller in alignment with a position spaced by a predetermined distance, in the axial direction of the roller from the temperature distribution center.

Claim 13

The thermal fixing device according to claim 2 , wherein different types of thermal cutoff devices are provided as the thermal cutoff device.

Claim 14

The thermal fixing device according to claim 9 , wherein the temperature sensor and at least one of the plurality of thermal cutoff devices are disposed on the same plane including the axis of the roller.

Claim 15

The thermal fixing device according to claim 9 , wherein each of the plurality of thermal cutoff devices has a temperature sensing element that senses a temperature, and each temperature sensing element is disposed facing the surface of the roller in alignment with a position spaced by a predetermined distance, in the axial direction of the roller from the temperature distribution center.

Claim 16

The thermal fixing device according to claim 9 , wherein different types of thermal cutoff devices are provided as the thermal cutoff device.

Claim 17

The thermal fixing device according to claim 13 , wherein each of the plurality of thermal cutoff devices has a temperature sensing element that senses a temperature, and each temperature sensing element is disposed facing the surface of the roller in alignment with a position spaced by a predetermined distance, in the axial direction of the roller from the temperature distribution center.

Claim 18

The thermal fixing device according to claim 13 , wherein different types of thermal cutoff devices are provided as the thermal cutoff device.

Claim 19

The thermal fixing device according to claim 16 , wherein different types of thermal cutoff devices are provided as the thermal cutoff device.

Claim 20

A thermal fixing device, comprising: a roller; a heater that heats the roller; a temperature sensor provided proximate the roller to sense a temperature of the roller; and a thermal cutoff device provided proximate the roller to interrupt power supply to the heater, wherein the temperature sensor and the thermal cutoff device are disposed symmetrically with respect to an axial center of the roller, and are coplanar with the axial center of the roller.

Claim 21

A thermal fixing device, comprising: a roller; a heater that heats the roller; a temperature sensor provided proximate the roller to sense a temperature of the roller; and a thermal cutoff device provided proximate the roller to interrupt power supply to the heater, wherein the temperature sensor and the thermal cutoff device are disposed symmetrically with respect to an axial center of the roller, and are coplanar with the axial center of the roller.

Claim 22

A thermal fixing device, comprising: a roller; a heater that heats the roller; a temperature sensor provided proximate the roller to sense a temperature of the roller; and a plurality of thermal cutoff devices proximate the roller to interrupt power supply to the heater, wherein the plurality of thermal cutoff devices are disposed on the same circumference about an axis of the roller.

Claim 23

A thermal fixing device, comprising: a roller; a heater that heats the roller; a temperature sensor provided proximate the roller to sense a temperature of the roller; and a plurality of thermal cutoff devices proximate the roller to interrupt power supply to the heater, wherein the plurality of thermal cutoff devices are disposed on the same circumference about an axis of the roller.

Claim 24

The thermal fixing device according to claim 20 , wherein the heater is provided inside the roller in the axial direction of the roller.

Claim 25

An image forming device that forms a toner image on a recording medium, comprising: a thermal fixing device that heats and presses the recording medium having the toner image to fix the toner image onto the recording medium, the thermal fixing device comprising: a roller; a heater that heats the roller; a temperature sensor provided proximate the roller to sense a temperature of the roller; and a thermal cutoff device provided proximate the roller to interrupt power supply to the heater, wherein the heater has a temperature distribution that is symmetrical in an axial direction of the roller with respect to a temperature distribution center, and the temperature sensor and the thermal cutoff device are disposed facing a surface of the roller in alignment with symmetrical positions spaced by a predetermined distance, in the axial direction of the roller from the temperature distribution center.

Claim 26

An image forming device that forms a toner image on a recording medium, comprising: a thermal fixing device that heats and presses the recording medium having the toner image to fix the toner image onto the recording medium, the thermal fixing device comprising: a roller; a heater that heats the roller; a temperature sensor provided proximate the roller to sense a temperature of the roller; and a thermal cutoff device provided proximate the roller to interrupt power supply to the heater, wherein the heater has a temperature distribution that is symmetrical in an axial direction of the roller with respect to a temperature distribution center, and the temperature sensor and the thermal cutoff device are disposed facing a surface of the roller in alignment with symmetrical positions spaced by a predetermined distance, in the axial direction of the roller from the temperature distribution center.

Claim 27

An image forming device that forms a toner image on a recording medium, comprising: a thermal fixing device that heats and presses the recording medium having the toner image to fix the toner image onto the recording medium, the thermal fixing device comprising: a roller; a heater that heats the roller; a temperature sensor provided proximate the roller to sense a temperature of the roller; and a thermal cutoff device provided proximate the roller to interrupt power supply to the heater, wherein the temperature sensor and the thermal cutoff device are disposed symmetrically with respect to an axial center of the roller, and are coplanar with the axial center of the roller.

Claim 28

An image forming device that forms a toner image on a recording medium, comprising: a thermal fixing device that heats and presses the recording medium having the toner image to fix the toner image onto the recording medium, the thermal fixing device comprising: a roller; a heater that heats the roller; a temperature sensor provided proximate the roller to sense a temperature of the roller; and a thermal cutoff device provided proximate the roller to interrupt power supply to the heater, wherein the temperature sensor and the thermal cutoff device are disposed symmetrically with respect to an axial center of the roller, and are coplanar with the axial center of the roller.

Claim 29

An image forming device that forms a toner image on a recording medium, comprising: a thermal fixing device that heats and presses the recording medium having the toner image to fix the toner image onto the recording medium, the thermal fixing device comprising: a roller; a heater that heats the roller; a temperature sensor provided proximate the roller to sense a temperature of the roller; and a plurality of thermal cutoff devices provided proximate the roller to interrupt power supply to the heater, wherein the plurality of thermal cutoff devices are disposed on the same circumference about an axis of the roller.

Claim 30

An image forming device that forms a toner image on a recording medium, comprising: a thermal fixing device that heats and presses the recording medium having the toner image to fix the toner image onto the recording medium, the thermal fixing device comprising: a roller; a heater that heats the roller; a temperature sensor provided proximate the roller to sense a temperature of the roller; and a plurality of thermal cutoff devices provided proximate the roller to interrupt power supply to the heater, wherein the plurality of thermal cutoff devices are disposed on the same circumference about an axis of the roller.

Claim 31

A thermal fixing device, comprising: a roller; a heater that heats the roller; a temperature sensor provided proximate the roller to sense a temperature of the roller; and a thermal cutoff device provided proximate the roller to interrupt power supply to the heater, wherein the heater has a temperature distribution that is symmetrical in an axial direction of the roller with respect to a temperature distribution center, and at least one of the temperature sensor and the thermal cutoff device is disposed facing a surface of the roller in alignment with one of symmetrical positions spaced by a predetermined distance, in the axial direction of the roller from the temperature distribution center.

Claim 32

A thermal fixing device, comprising: a roller; a heater that heats the roller; a temperature sensor provided proximate the roller to sense a temperature of the roller; and a thermal cutoff device provided proximate the roller to interrupt power supply to the heater, wherein the heater has a temperature distribution that is symmetrical in an axial direction of the roller with respect to a temperature distribution center, and at least one of the temperature sensor and the thermal cutoff device is disposed facing a surface of the roller in alignment with one of symmetrical positions spaced by a predetermined distance, in the axial direction of the roller from the temperature distribution center.

Claim 33

The thermal fixing device according to claim 25 , wherein the predetermined distance is a distance, in the axial direction of the roller, between the temperature distribution centers and an intersection between temperature distribution curves obtained when heating by the heater is started and when heating by the heater is stabilized.