Fixing device and image forming apparatus in which movement of sensor holding member relative to heater holding member is restricted by sensor holding member being engaged with heater holding member

1 . A fixing device comprising:

a tubular and rotatable fixing belt;

a heating device that includes a heater configured to heat the fixing belt and faces an inner peripheral surface of the fixing belt; and

a pressurizing member that sandwiches the fixing belt with the heater, forms a fixing nip portion, in which a recording medium is sandwiched and transported, between the pressurizing member and the fixing belt, and causes the fixing belt to be driven and rotated,

wherein the heating device includes

a heater holding member that holds the heater,

a temperature sensor that faces the heater and is disposed in the heater holding member, and

a sensor holding member that is assembled with the heater holding member in which the temperature sensor is disposed in a direction in which the sensor holding member faces the temperature sensor,

the sensor holding member includes a biasing member that faces the heater holding member via the temperature sensor and biases the temperature sensor in a first direction directed from the temperature sensor to the heater, and

the heater holding member includes:

a locking portion that includes a pair of projecting members whose end portions on a side in the second direction opposite to the first direction are bent in directions toward each other to form an opening; and

an engaged portion having a recess that is open to the first direction and provided at a position different from that of the locking portion in a longitudinal direction of the heater holding member,

a width of the one end portion of the sensor holding member in the longitudinal direction is formed to be smaller than the opening,

a convex portion projecting toward the second direction is formed on a side of the other end of the sensor holding member in the longitudinal direction,

the one end portion of the sensor holding member is locked by being inserted into the opening, and

in a state in which the one end portion of the sensor holding member is locked to the locking portion, the sensor holding member is loaded in the first direction against a biasing force of the biasing member and is moved in the longitudinal direction until the convex portion of the sensor holding member is positioned on a first direction side of the recess of the heater holding member, and upon release of the load, the convex portion and the recess become engaged by the biasing force of the biasing member.

2 . The fixing device according to claim 1 ,

wherein the biasing member is a compression spring, and

a groove that receives one end of the compression spring is formed in a surface of the temperature sensor facing the sensor holding member in a state where the temperature sensor is disposed in the heater holding member.

3 . The fixing device according to claim 1 ,

wherein the heating device further includes a reinforcing member that abuts on the sensor holding member and is fixed to the sensor holding member with the reinforcing member facing the heater holding member via the sensor holding member.

4 . An image forming apparatus comprising:

the fixing device according to claim 1 ; and

an image forming device that forms an image on a recording medium,

wherein the fixing device causes the image formed on the recording medium by the image forming device to be fixed.