Fixing device and image forming apparatus

• US 20090238596A1
• Filed: 05/22/2009
• Published: 09/24/2009
• Est. Priority Date: 01/28/2004
• Status: Active Grant

• Current Assignee: Oki Data Corporation (OKI Electric Industry Company Limited)
• Original Assignee: Oki Data Corporation (OKI Electric Industry Company Limited)
• Inventors: Shiobara, Toshimasa, Aida, Koji
• Granted Patent: US 8,032,047 B2
• Time in Patent Office: Days
• US Class Current: 399/69
• CPC Class Codes: G03G 15/2039 with means for controlling the fixing temperature

Abstract

A fixing device includes a non-contacting thermistor (54) disposed in the vicinity of the surface of a heat roller (21) and an upper cover temperature thermistor (60) for detecting the temperature of a pressure roller (22). The calculated surface temperature (T) of the heat roller 21 is calculated based on the detected temperature (T1) detected by the non-contacting thermistor (54), the detected temperature (T2) detected by the upper cover temperature thermistor (60), the distance (L1) from the non-contacting thermistor (54) to the surface of the heat roller (21) and the distance (L2) from the non-contacting thermistor (54) to the upper cover (51).

Claims

1. A fixing device for fixing a developer image to a recording medium, said fixing device comprising:

a heat source;

a heating member heated by said heat source so as to heat said recording medium;

a pressing member disposed in contact with said heating member, said pressing member having no heat source;

a first temperature detecting unit that detects a temperature of said heating member, and is remote from said heating member;

a third temperature detecting unit disposed in contact with said pressing member, said third temperature detecting unit detecting a temperature transmitted from said heating member; and

a control unit that compensates a detected temperature detected by said first temperature detecting unit based on a detected temperature detected by said third temperature detecting unit, and controls said heat source based on a compensated detected temperature.

2. The fixing device according to claim 1, further comprising a pressure member urged against said heating member so as to nip said recording medium therebetween,

wherein said third temperature detecting unit detects a temperature of said pressure member.

3. An image forming apparatus having said fixing device according to claim 1, said image forming apparatus further comprising:

a medium feeding unit that feeds said recording medium; and

an image forming unit that forms a developer image on said recording medium,

wherein said fixing device fixes said developer image on said recording medium.

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

a cover provided so as to cover said heating member, said cover having a partition wall so that a substantially closed space is formed by said partition wall and a surface of said heating member, and

wherein said first temperature detecting unit is disposed in said substantially closed space.

5. The fixing device according to claim 1, wherein temperature detections by said first temperature detecting unit and said third temperature detecting unit are performed after said heating member and said pressing member start rotating.

6. The fixing device according to claim 5, wherein said control unit controls said heating member based on a calculated surface temperature T of said heating member based on the following equation:

T=T1+(a*T_x3)+b

where T1 indicates a detected temperature detected by said first temperature detecting unit, T_x3 indicates a detected temperature detected by said third temperature detecting unit, and a and b are constants.

7. The fixing device according to claim 6, wherein:

said control unit determines an accumulated temperature index Q according to the following equation;

Q={c*T1(start)+τ

*T3(start)+∫

(κ

(T1+T3)}dt

where T1(start) and T3(start) respectively indicate temperatures detected by said first temperature detecting unit and said third temperature detecting unit when said heating source is turned on, c, τ and

κ

are constants, and

wherein, when said accumulated temperature index Q is less than a predetermined value Qs, said control unit determines said calculated surface temperature T of said heating member based on the above equation and

wherein, when said accumulated temperature index Q is greater than or equal to said predetermined value Qs, said control unit determines said calculated surface temperature T of said heating member based on the following additional equation;

T=T1+d

where d is a constant that has been experimentally determined.