FIXING APPARATUS, IMAGE FORMING APPARATUS INCLUDING SAME FIXING APPARATUS, METHOD FOR CONTROLLING FIXING APPARATUS, PROGRAM FOR CONTROLLING FIXING APPARATUS, COMPUTER-READABLE RECORDING MEDIUM

Abstract

An image forming apparatus includes a control circuit for controlling amounts of heat transfer of a fixing roller and a pressure roller such that (Q1−Q0)/Hc≦11 (more preferably, ≦0) is satisfied where Q0 represents total amounts (J) of heat that the fixing roller and the pressure roller have during standby or just after completion of warm-up, Q1 represents total amounts (J) of heat that the fixing roller and the pressure roller have and that are saturated as a result of continuously fixing unfixed images onto recording materials and the heat amounts that the fixing roller and the pressure roller have are saturated, and Hc represents a heat capacity (J/° C.) of the fixing roller and the pressure roller.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically illustrating a structure of a fixing apparatus according to one embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating a fixing apparatus according to another embodiment of the present invention.

FIG. 3 is a diagram schematically illustrating a fixing apparatus according to one comparative example to the present invention.

FIG. 4 is a diagram illustrating changes of electric power consumptions of the fixing apparatuses shown in FIG. 1, FIG. 2, and FIG. 3, respectively.

FIG. 5( a) is a diagram illustrating changes of temperatures of component members of the fixing apparatuses shown in FIG. 1.

FIG. 5( b) is a diagram illustrating changes of temperatures of component members of the fixing apparatuses shown in FIG. 2.

FIG. 5( c) is a diagram illustrating changes of temperatures of component members of the fixing apparatuses shown in FIG. 3.

FIG. 6( a) is a diagram illustrating (i) temperature distributions that the components of the fixing apparatus shown in FIG. 1 have in the circumferential direction of the pressure roller just before passage of sheets and (ii) temperature distributions that the components thereof have in the circumferential direction just after the passage of sheets.

FIG. 6( b) is a diagram illustrating (i) temperature distributions that the components of the fixing apparatus shown in FIG. 2 have in the circumferential direction of the pressure roller just before passage of sheets and (ii) temperature distributions that the components thereof have in the circumferential direction just after the passage of sheets.

FIG. 6( c) is a diagram illustrating (i) temperature distributions that the components of the fixing apparatus shown in FIG. 3 have in the circumferential direction of the pressure roller just before passage of sheets and (ii) temperature distributions that the components thereof have in the circumferential direction just after the passage of sheets.

FIG. 7 is a diagram illustrating an amount of heat accumulated in each fixing member per unit of time during operation of each of the fixing apparatuses shown in FIG. 1, FIG. 2, and FIG. 3.

FIG. 8 is a diagram illustrating (i) a relation between an average increased temperature and the maximum electric power consumption in cases where controlled temperature of the pressure roller shown in FIG. 1 is changed during standby, and (ii) a relation between (a) the average increased temperature and (b) a difference between a temperature of the pressure roller at the beginning of the operation and a temperature of the pressure roller after the end of the operation.

FIG. 9 is a diagram schematically illustrating a fixing apparatus according to still another embodiment of the present invention.

FIG. 10 is a diagram schematically illustrating a fixing apparatus according to yet another embodiment of the present invention.

FIG. 11 is a diagram schematically illustrating a fixing apparatus according to another comparative example to the present invention.

FIG. 12( a) is a diagram illustrating changes of electric power consumption of each of the fixing apparatuses shown in FIGS. 9 and 11.

FIG. 12( b) is a diagram illustrating changes of electric power consumption of each of the fixing apparatuses shown in FIGS. 10 and 11.

FIG. 13( a) is a diagram illustrating changes of temperatures of component members of the fixing apparatus shown in FIG. 9.

FIG. 13( b) is a diagram illustrating changes of temperatures of component members of the fixing apparatus shown in FIG. 10.

FIG. 13( c) is a diagram illustrating changes of temperatures of component members of the fixing apparatus shown in FIG. 11.

FIG. 14( a) is a diagram illustrating an amount of heat accumulated in each fixing member per unit of time during operation of each of the fixing apparatuses shown in FIG. 9 and FIG. 11.

FIG. 14( b) is a diagram illustrating an amount of heat accumulated in each fixing member per unit of time during operation of each of the fixing apparatuses shown in FIG. 10 and FIG. 11.

FIG. 15 is a diagram illustrating (i) a relation between an average increased temperature and the maximum electric power consumption in cases where controlled temperature of the pressure roller of the fixing apparatus shown in FIG. 9 is changed during standby, and (ii) a relation between (a) the average increased temperature and (b) a difference between a temperature of the pressure roller at the beginning of the operation and a temperature of the pressure roller after the end of the operation.

FIG. 16 is a diagram schematically illustrating an image forming apparatus according to one embodiment of the present invention.

FIG. 17 is a diagram schematically illustrating an image forming apparatus according to another embodiment of the present invention.

Claims

1. A fixing apparatus, comprising: a plurality of fixing members for heating and pressing an unfixed image, formed on a recording material, by sandwiching and transporting the recording material; andcontrol means for controlling amounts of heat transfer of the fixing members such that Formula (1), (Q1−Q0)/Hc≦11, is satisfied where Q0 represents total amounts (J) of heat that the fixing members have during standby or just after completion of warm-up, Q1 represents total amounts (J) of heat that the fixing members have and that are saturated as a result of continuously fixing unfixed images onto recording materials, and Hc represents a heat capacity (J/° C.) of the fixing members.

2. A fixing apparatus, comprising: a plurality of fixing members for heating and pressing an unfixed image, formed on a recording material, by sandwiching and transporting the recording material; andcontrol means for controlling amounts of heat transfer of the fixing members such that Formula (2), (Q1−Q0)/Hc≦0 is satisfied where Q0 represents total amounts (J) of heat that the fixing members have during standby or just after completion of warm-up, Q1 represents total amounts (J) of heat that the fixing members have and that are saturated as a result of continuously fixing unfixed images onto recording materials, and Hc represents a heat capacity (J/° C.) of the fixing members.

3. The fixing apparatus as set forth in claim 1, further comprising: a plurality of heating means for heating the fixing members,wherein:said control means includes at least one of (a) a temperature control section for controlling set temperatures that the fixing members have during the standby and set temperatures that the fixing members have during the fixing of the unfixed images onto the recording materials; (b) a rotation control section for controlling rotation timing of each of the fixing members; and (c) an electric power supply section for controlling a ratio of electric power to be supplied to the plurality of heating means for heating the fixing members.

4. The fixing apparatus as set forth in claim 1, wherein: said control means controls the amounts of the heat transfer of the fixing members such that Formula (3), (Q1−Q0)/Hc≦−13, is satisfied.

5. The fixing apparatus as set forth in claim 3, wherein: as one of the heating means, a heating source is provided in a fixing member, making contact with each recording material so as to meet a surface on which no image is formed, of the fixing members.

6. The fixing apparatus as set forth in claim 5, wherein: said control means carries out control such that the heating source provided in the fixing member making contact with each recording material so as to meet a surface on which no image is formed supplies heat only during either the standby or the warm-up.

7. The fixing apparatus as set forth in claim 3, wherein: as one of the heating means, a heating source is provided outside at least any one of the fixing members so as to heat the fixing member.

8. The fixing apparatus as set forth in claim 7, wherein: the fixing member heated by the heating source provided outside the fixing member is provided with a metal core and an elastic layer having a thermal conductivity smaller than a thermal conductivity of the metal core.

9. The fixing apparatus as set forth in claim 7, wherein: as one of the heating means, a heating source is provided in the fixing member heated by the heating source provided outside the fixing member.

10. The fixing apparatus as set forth in claim 9, wherein: said control means carries out control such that the heating source provided in the fixing member heated by the heating source provided outside the fixing member radiates heat during the standby, and such that the heating source provided outside the fixing member radiates heat while the fixing apparatus carries out the operation of fixing the unfixed images onto the recording materials.

11. The fixing apparatus as set forth in claim 1, wherein: the operation of fixing the unfixed images onto the recording materials is carried out at a processing speed of 300 mm/sec or faster.

12. The fixing apparatus as set forth in claim 3, wherein: the fixing members consist of a fixing roller and a pressure roller, the fixing roller and the pressure roller each having the heating means therein, andtemperature detecting means for detecting respective temperatures of the fixing roller and the pressure roller is provided.

13. A image forming apparatus, comprising a fixing apparatus, said fixing apparatus including:a plurality of fixing members for heating and pressing an unfixed image, formed on a recording material, by sandwiching and transporting the recording material; andcontrol means for controlling amounts of heat transfer of the fixing members such that Formula (1), (Q1−Q0)/Hc≦11, is satisfied where Q0 represents total amounts (J) of heat that the fixing members have during standby or just after completion of warm-up, Q1 represents total amounts (J) of heat that the fixing members have and that are saturated as a result of continuously fixing unfixed images onto recording materials, and Hc represents a heat capacity (J/° C.) of the fixing members.

14. A method for controlling a fixing apparatus including a plurality of fixing members for heating and pressing an unfixed image, formed on a recording material, by sandwiching and transporting the recording material, said method, comprising the step of:controlling amounts of heat transfer of the fixing members such that Formula (1), (Q1−Q0)/Hc≦11 is satisfied where Q0 represents total amounts (J) of heat that the fixing members have during standby or just after completion of warm-up, Q1 represents total amounts (J) of heat that the fixing members have and that are saturated as a result of continuously fixing unfixed images onto recording materials, and Hc represents a heat capacity (J/° C.) of the fixing members.

15. A method for controlling a fixing apparatus including a plurality of fixing members for heating and pressing an unfixed image, formed on a recording material, by sandwiching and transporting the recording material, said method, comprising the step of:controlling amounts of heat transfer of the fixing members such that Formula (2), (Q1−Q0)/Hc≦0 is satisfied where Q0 represents total amounts (J) of heat that the fixing members have during standby or just after completion of warm-up, Q1 represents total amounts (J) of heat that the fixing members have and that are saturated as a result of continuously fixing unfixed images onto recording materials, and Hc represents a heat capacity (J/° C.) of the fixing members.

16. A control program for realizing, in a computer, a method for controlling a fixing apparatus including a plurality of fixing members for heating and pressing an unfixed image, formed on a recording material, by sandwiching and transporting the recording material, said control program causing the computer to control amounts of heat transfer of the fixing members such that Formula (1), (Q1−Q0)/Hc≦11, is satisfied where Q0 represents total amounts (J) of heat that the fixing members have during standby or just after completion of warm-up, Q1 represents total amounts (J) of heat that the fixing members have and that are saturated as a result of continuously fixing unfixed images onto recording materials, and Hc represents a heat capacity (J/° C.) of the fixing members.

17. A computer-readable recording medium storing a control program for realizing, in a computer, a method for controlling a fixing apparatus including a plurality of fixing members for heating and pressing an unfixed image, formed on a recording material, by sandwiching and transporting the recording material, said control program causing the computer to control amounts of heat transfer of the fixing members such that Formula (1), (Q1−Q0)/Hc≦11, is satisfied where Q0 represents total amounts (J) of heat that the fixing members have during standby or just after completion of warm-up, Q1 represents total amounts (J) of heat that the fixing members have and that are saturated as a result of continuously fixing unfixed images onto recording materials, and Hc represents a heat capacity (J/° C.) of the fixing members.