Fixing device and image forming apparatus
A fixing device includes a belt member, a heater, a base layer, and an opposed layer. The heater is provided on an inner circumferential surface of the belt member. The base layer includes a first surface on a heater side and a second surface on an opposite side to the first surface. The opposed layer covers the second surface and is opposed to the inner circumferential surface of the belt member. The base layer and the opposed layer satisfy the following conditional expression (1), 0<( Tb×Da )/( Ta×Db )≤1.17 (1) where Ta is a thickness of the base layer in millimeters, Tb is a thickness of the opposed layer in millimeters, Da is a thermal diffusivity of the base layer in square millimeters per second, and Db is a thermal diffusivity of the opposed layer in square millimeters per second.
1. A fixing device comprising:
a belt member;
a heater provided on an inner circumferential surface of the belt member;
a base layer that includes a first surface on a heater side and a second surface on an opposite side to the first surface; and
an opposed layer that covers the second surface and is opposed to the inner circumferential surface of the belt member;
the base layer and the opposed layer satisfying the following conditional expression (1),
0<( Tb×Da )/( Ta×Db )≤1.17 (1)
where Ta is a thickness of the base layer in millimeters,
Tb is a thickness of the opposed layer in millimeters,
Da is a thermal diffusivity of the base layer in square millimeters per second, and
Db is a thermal diffusivity of the opposed layer in square millimeters per second.
2. The fixing device according to claim 1 , wherein
the thickness of the opposed layer is equal to or greater than 0.005 millimeters and equal to or less than 0.03 millimeters, and
the base layer and the opposed layer further satisfy the following conditional expression (2),
0.27≤( Tb×Da )/( Ta×Db ) (2).
3. The fixing device according to claim 1 , further comprising a lubricant that is provided between the opposed layer and the belt member.
4. The fixing device according to claim 1 , wherein
the base layer includes aluminum as a major component, and
the thickness of the opposed layer is equal to or less than 0.015 millimeters.
5. The fixing device according to claim 1 , wherein the opposed layer includes resin as a major component.
6. The fixing device according to claim 1 , wherein the thermal diffusivity of the base layer is greater than the thermal diffusivity of the opposed layer.
7. The fixing device according to claim 1 , wherein the thickness of the base layer is greater than the thickness of the opposed layer.
8. The fixing device according to claim 1 , wherein the belt member includes resin as a major component.
9. The fixing device according to claim 1 , wherein the base layer and the opposed layer transmit heat generated by the heater to the belt member.
10. The fixing device according to claim 1 , further comprising a pressure-applying member that is provided in a state of being able to come into contact with a surface of the belt member.
11. An image forming apparatus comprising
a fixing device including:
a belt member;
a heater provided on an inner circumferential surface of the belt member;
a base layer that includes a first surface on a heater side and a second surface on an opposite side to the first surface; and
an opposed layer that covers the second surface and is opposed to the inner circumferential surface of the belt member;
the base layer and the opposed layer satisfying the following conditional expression (1),
0<( Tb×Da )/( Ta×Db )≤1.17 (1)
where Ta is a thickness of the base layer in millimeters,
Tb is a thickness of the opposed layer in millimeters,
Da is a thermal diffusivity of the base layer in square millimeters per second, and
Db is a thermal diffusivity of the opposed layer in square millimeters per second.