IP Library Granted Patent US 12687806
Granted Patent B2
US 12687806 · App. 18/836,609 · Granted Jul 21, 2026

Fixing device and image forming apparatus incorporating same

Inventors: Daisuke Hirano (Kanagawa, JP); Yuusuke Furuichi (Kanagawa, JP); Naohiro Kumagai (Kanagawa, JP)
Assignee: Ricoh Company, Ltd.
G03G15/2053G03G15/2064
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Quick Facts
Patent No.
US 12687806
App. No.
18/836,609
Granted
Jul 21, 2026
Kind
B2
Abstract

A fixing device includes a rotator, a pressure rotator, a heater, a conductor, and a resistor. The rotator includes a conductive layer. The pressure rotator presses the rotator to form a fixing nip between the rotator and the pressure rotator. The heater is in contact with an inner surface of the rotator to heat the rotator. The conductor is in contact with the conductive layer of the rotator and has a resistance value larger than 100 kΩ. The resistor has one end electrically coupled in series to the conductor and another end grounded via an image forming apparatus.

Claims (58)

1 . A fixing device comprising:

a rotator including a conductive layer;

a pressure rotator configured to press the rotator to form a fixing nip between the rotator and the pressure rotator;

a heater in contact with an inner surface of the rotator, the heater configured to heat the rotator;

a conductor in contact with the conductive layer of the rotator, the conductor having a resistance value larger than 100 kΩ; and

a resistor having one end electrically coupled in series to the conductor and another end configured to be grounded via an image forming apparatus, wherein a resistance value of the resistor is larger than 100 kΩ.

2 . The fixing device according to claim 1 , wherein a sum of the resistance values of the conductor and the resistor is 4 MΩ or less.

3 . The fixing device according to claim 1 , wherein the resistance value of the conductor is 2 MΩ or more.

4 . The fixing device according to claim 1 , wherein the conductive layer is a base layer of the rotator, the conductive layer being the inner surface of the rotator.

5 . An image forming apparatus comprising:

at least one image forming device configured to form an image on a recording medium; and

the fixing device according to claim 1 .

6 . The fixing device according to claim 1 , wherein

the conductor has a shape of a sheet.

7 . The fixing device according to claim 1 , further comprising:

a stay; and

a guide portion, wherein

the conductor is between the stay and the guide portion, and the conductor is affixed to the stay.

8 . The fixing device according to claim 1 , further comprising:

a stay; and

a heater holder configured to hold the heater, wherein

the conductor is between the stay and the heater holder, and

the pressure rotator is further configured to apply a pressure which causes the stay and the conductor to come into contact.

9 . A fixing device comprising:

a rotator including a conductive layer;

a pressure rotator configured to press the rotator to form a fixing nip between the rotator and the pressure rotator;

a heater in contact with an inner surface of the rotator, the heater configured to heat the rotator;

a conductor in contact with the conductive layer of the rotator, the conductor having a resistance value larger than 100 kΩ; and

a resistor having one end electrically coupled in series to the conductor and another end configured to be grounded via an image forming apparatus, wherein the resistance value of the conductor is larger than a resistance value of the conductive layer.

10 . An image forming apparatus comprising:

at least one image forming device configured to form an image on a recording medium; and

the fixing device according to claim 9 .

11 . The fixing device according to claim 9 , wherein a sum of the resistance values of the conductor and the resistor is 4 MΩ or less.

12 . The fixing device according to claim 9 , wherein the resistance value of the conductor is 2 MΩ or more.

13 . The fixing device according to claim 9 , wherein

the conductive layer is a base layer of the rotator, the conductive layer being the inner surface of the rotator.

14 . The fixing device according to claim 9 , further comprising:

a stay; and

a guide portion, wherein

the conductor is between the stay and the guide portion, and the conductor is affixed to the stay.

15 . The fixing device according to claim 9 , further comprising:

a stay; and

a heater holder configured to hold the heater, wherein

the conductor is between the stay and the heater holder, and

the pressure rotator is further configured to apply a pressure which causes the stay and the conductor to come into contact.

16 . A fixing device comprising:

a rotator including a conductive layer;

a pressure rotator configured to press the rotator to form a fixing nip between the rotator and the pressure rotator;

a heater in contact with an inner surface of the rotator, the heater configured to heat the rotator;

a conductor in contact with the conductive layer of the rotator, the conductor having a resistance value larger than 100 kΩ; and

a resistor having one end electrically coupled in series to the conductor and another end configured to be grounded via an image forming apparatus, wherein the resistance value of the conductor is within a range of ±10% of a resistance value of the resistor.

17 . An image forming apparatus comprising:

at least one image forming device configured to form an image on a recording medium; and

the fixing device according to claim 16 .

18 . The fixing device according to claim 16 , wherein a sum of the resistance values of the conductor and the resistor is 4 MΩ or less.

19 . The fixing device according to claim 16 , wherein the resistance value of the conductor is 2 MΩ or more.

20 . The fixing device according to claim 16 , wherein

the conductive layer is a base layer of the rotator, the conductive layer being the inner surface of the rotator.