Source: http://www.google.com/patents/US7308216?dq=7,433,694
Timestamp: 2014-03-08 09:21:06
Document Index: 346188898

Matched Legal Cases: ['Application No. 2004', 'art 1', 'art 1', 'art 1', 'art 1', 'art 1', 'art 1', 'art 1', 'art 1', 'art 1']

Patent US7308216 - Image forming apparatus and method to supply power to a fixing device - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA fixing device for fixing an image formed on a recording material in an image forming apparatus includes a fixing member configured to fix an image formed on the recording material, a heating part that heats the fixing member, a storage unit that is charged by an external power source to supply power...http://www.google.com/patents/US7308216?utm_source=gb-gplus-sharePatent US7308216 - Image forming apparatus and method to supply power to a fixing deviceAdvanced Patent SearchPublication numberUS7308216 B2Publication typeGrantApplication numberUS 11/208,753Publication dateDec 11, 2007Filing dateAug 23, 2005Priority dateAug 23, 2004Fee statusPaidAlso published asUS20060127118Publication number11208753, 208753, US 7308216 B2, US 7308216B2, US-B2-7308216, US7308216 B2, US7308216B2InventorsKazuhito Kishi, Susumu Matsusaka, Yasuhisa Kato, Akiyasu Amita, Masami Okamoto, Yasutada Tsukioka, Hiromasa Takagi, Ryuichi KikegawaOriginal AssigneeRicoh Company, Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (23), Non-Patent Citations (6), Referenced by (8), Classifications (6), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetImage forming apparatus and method to supply power to a fixing deviceUS 7308216 B2Abstract A fixing device for fixing an image formed on a recording material in an image forming apparatus includes a fixing member configured to fix an image formed on the recording material, a heating part that heats the fixing member, a storage unit that is charged by an external power source to supply power to the heating part, and a control unit that controls the storage unit so as not to supply power to the heating part during a warming-up period from when a power switch of the image forming apparatus switches on to when the image forming apparatus becomes ready to start an image forming operation and that controls the external power source and the storage unit to supply power to the heating part during a returning period from when an off-mode is completed to when the image forming apparatus becomes ready to start the image forming operation.
CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Japanese Patent Application No. 2004-242052 filed in the Japanese Patent Office on Aug. 23, 2004, the entire contents of each of which is herein incorporated by reference.
SUMMARY OF THE INVENTION According to an aspect of the present invention, a fixing device fixes an image formed on a recording material in an image forming apparatus. The fixing device includes a fixing member disposed on a recording material conveyance path and configured to fix by heat an image formed on the recording material, a heating part configured to heat the fixing member and a storage unit configured to be charged by an external power source and to supply power to the heating part.
As shown by a line �a1� (both the main power supply unit and the auxiliary power supply unit) of FIG. 7, when the temperature T of the fixing roller 14 is a room temperature, for example, about 23 degrees centigrade, the temperature of the fixing roller 14 rises to a target temperature �T0�, for example, about 180 degrees centigrade, by supplying power to the heating part 1 from both the main power supply unit 2 and the storage unit 3 in a target time �t0�, for example, about 10 seconds.
As shown by a line �b� (the main power supply unit only) and a line �a2� (both the main power supply unit and the auxiliary power supply unit) of FIG. 7, when heating the fixing roller 14 shortly after not a long time has elapsed since the stop of the preceding heating operation, the temperature T of the fixing roller 14 may be higher than a predetermined high threshold temperature �T1�, for example, about 140 degrees centigrade. In this high temperature condition, if the fixing roller 14 is heated by supplying power to the heating part 1 from both the main power supply unit 2 and the storage unit 3, the temperature of the fixing roller 14 rises to the target temperature �T0� in less than the target time �t0�, as shown by the line �a2�. If the fixing roller 14 is heated by supplying power to the heating part 1 from only the main power supply unit 2, the temperature of the fixing roller 14 can be raised to the target temperature �T0� within the target time �t0� as shown by the line �b�. If the temperature T of the fixing roller 14, which is detected by the fixing temperature detecting unit 8, is higher than the high threshold temperature �T1�, the supply of power from the storage unit 3 is stopped. By preventing unnecessary reduction of the warm-up time for raising the temperature of the fixing roller 14 to the target temperature �T0�, an excess power consumption can be controlled and an overshoot caused by rapid temperature rise can be minimized or avoided.
In contrast, when the fixing roller 14 is heated in a colder environment, the temperature T of the fixing roller 14 may be lower than a predetermined low threshold temperature �T2�, for example, about 15 degrees centigrade. In this low temperature condition, as shown by a line �c� of FIG. 7, it takes longer than the target time �t0� to raise the temperature of the fixing roller 14 to the target temperature �T0�. In this case, the power supplying time of the storage unit 3 becomes longer and an amount of the consumed power of the storage unit 3 increases, so that the remaining amount of the stored power of the storage unit 3 to be used for supplying to the heating part 1 of the fixing roller 14 during the sheet passing operation decreases. In such a low temperature condition, the temperature of the recording material P is low as well, and power is supplied to the heating part 1 during the sheet passing operation. However, the voltage of the storage unit 3 is lower than usual and the power supplied from the storage unit 3 becomes smaller. Consequently, a fixing failure typically occurs due to insufficient heating of the fixing roller 14. If the temperature T of the fixing roller 14 is lower than the low threshold temperature T2 at the start of warming-up the fixing roller 14, the fixing roller 14 may be warmed-up by using only the main power supply unit 2 without using the storage unit 3. By lowering power consumption at the time of warming-up the fixing roller 14 and by using the saved power of the storage unit 3 during the sheet passing operation, a fixing failure can be prevented even in a low temperature condition.
FIG. 8 is a flowchart of AC power supply control operation steps of the control unit 60 at the time of warming-up the fixing roller 14, according to an embodiment of the present invention. First, the fixing temperature detecting unit 8 detects the temperature T of the fixing roller 14 before warming-up the fixing roller 14 in step S1. Then, the control unit 60 determines whether the detected temperature T of the fixing roller 14 is less than or equal to the target temperature �T0� (T≦T0) in step S2.
If the answer is NO in step S2, the control operation proceeds to step S6. In step S6, the control unit 60 switches OFF the power supply from the main power supply unit 2 to the main heating member 1 a. If the answer is YES in step S2, the control unit 60 switches ON the power supply from the main power supply unit 2 to the main heating member 1 a in step S3. Subsequently, the fixing temperature detecting unit 8 detects the temperature T of the fixing roller 14 during warming-up the fixing roller 14 in step S4. Then, the control unit 60 determines whether the temperature T of the fixing roller 14 is greater than or equal to the target temperature �T0� (T≧T0) in step S5. If the answer is NO in step S5, the control operation returns to reexecute step S4. If the answer is YES in step S5, the control unit 60 switches OFF the power supply from the main power supply unit 2 to the main heating member 1 a in step S6.
FIG. 9 is a flowchart of DC power supply control operation steps of the control unit 60 at the time of warming-up the fixing roller 14, according to an embodiment of the present invention. First, the fixing temperature detecting unit 8 detects the temperature T of the fixing roller 14 before warming-up the fixing roller 14 in step S11. Then, the control unit 60 determines whether the detected temperature T of the fixing roller 14 is less than or equal to the high threshold temperature �T1� (T≦T1) in step S12. If the answer is NO in step S12, the control operation proceeds to step S17. In step S17, the control unit 60 switches OFF the power supply from the storage unit 3 to the auxiliary heating members 1 b. In this condition, as the initial temperature of the fixing roller 14 is high, the fixing roller 14 can be rapidly warmed-up without using the storage unit 3. The line �b� of FIG. 7 indicates this high temperature condition.
If the answer is YES in step S12, the control unit 60 determines whether the detected temperature T of the fixing roller 14 is greater than or equal to the low threshold temperature �T2� (T≧T2) in step S13. If the answer is NO in step S13, the control operation proceeds to step S17, and the control unit 60 switches OFF the power supply from the storage unit 3 to the auxiliary heating members 1 b. In this condition, as the initial temperature of the fixing roller 14 is low, the fixing roller 14 cannot be as rapidly warmed-up, even if the storage unit 3 is used. The line �c� of FIG. 7 indicates this low temperature condition.
If the answer is YES in step S13, the control unit 60 switches ON the power supply from the storage unit 3 to the auxiliary heating members 1 b at the time of warming-up the fixing roller 14 in step S14. Then, the fixing temperature detecting unit 8 detects the temperature T of the fixing roller 14 at the time of warming-up the fixing roller 14 in step S15. Subsequently, the control unit 60 determines whether the temperature T of the fixing roller 14 is greater than or equal to the target temperature �T0� (T≧T0) in step S16.
If the answer is NO in step S16, the control operation returns to reexecute step S15. By supplying power from the storage unit 3 to the heating part 1, in addition to the power supplied from the main power supply unit 2 to the heating part 1, the temperature T of the fixing roller 14 can be raised to the target temperature �T0� within the target time �t0�. The line �a1� of FIG. 7 indicates this condition. If the answer is YES in step S16, the control unit 60 switches OFF the power supply from the storage unit 3 to the auxiliary heating members 1 b in step S17.
After the completion of the sheet passing operation, the supply of the both AC power and DC power is stopped. Specifically, the fixing temperature detecting unit 8 detects the temperature T of the fixing roller 14 at the time of the sheet passing operation in step S21. Subsequently, the control unit 60 determines whether the temperature T of the fixing roller 14 is less than or equal to the target temperature �T0� (T≦T0) in step S22.
FIG. 11 is a time chart for explaining a power supply operation of the fixing device 10 according to another embodiment of the present invention. The time chart of FIG. 11 is similar to the time chart of FIG. 5 except that the storage unit 3 is charged by the main power supply unit 2 during a period from when the power supply from the storage unit 3 to the auxiliary heating members 1 b is completed at the time of warming-up the fixing roller 14 (indicated by a reference character �t1� in FIG. 11) to when the power supply from the storage unit 3 to the auxiliary heating members 1 b is started at the time of the sheet passing operation (indicated by a reference character �t2� in FIG. 11). Immediately after the temperature of the fixing roller 14 is raised to the target temperature �T0� in the warming-up operation, the remaining power of the storage unit 3 is reduced, so that the voltage of the storage unit 3 is lowered. In this condition, even if a halogen heater rated at the same power is used, the output of the power of the halogen heater decreases.
So, in this embodiment, the storage unit 3 is charged by the main power supply unit 2 in a period between the �t1� and �t2� in which the power supplied from the main power supply unit 2 to the main heating member 1 a is small. In the period between the �t1� and �t2�, the small amount of power is supplied to the main heating member 1 a from the main power supply unit 2 to maintain the fixing roller 14 at the target temperature. By charging the storage unit 3 in this period, the power supplied from the storage unit 3 to the heating part 1 of the fixing roller 14 can be increased at the time of a sheet passing operation.
FIG. 12 is a flowchart of DC power supply control operation steps of the control unit 60 at the time of warming-up the fixing roller 14, according to another embodiment of the present invention. First, the fixing temperature detecting unit 8 detects the temperature T of the fixing roller 14 before warming-up the fixing roller 14 in step S31. Then, the control unit 60 determines whether the detected temperature T of the fixing roller 14 is greater than or equal to the target temperature T0 (T≧T0) in step S32. If the answer is NO in step S32, the control unit 60 switches ON the power supply from the storage unit 3 to the auxiliary heating members 1 b at the time of warming-up the fixing roller 14 in step S33. By supplying power to the heating part 1 of the fixing roller 14 from the storage unit 3 at the warming-up time, the temperature of the fixing roller 14 can be raised to the target temperature �T0� in the target time �t0� as indicated by the graph �a1� of FIG. 7. Then, the control operation returns to reexecute step S31.
If the answer is YES in step S32, the control unit 60 switches OFF the power supply from the storage unit 3 to the auxiliary heating members 1 b in step S34. In this condition, as the initial temperature of the fixing roller 14 is high, the fixing roller 14 can be rapidly warmed-up without using the storage unit 3. The line �b� of FIG. 7 indicates this high temperature condition. Then, in step S35, the storage unit 3 starts to be charged from the main power supply unit 2 (from the commercial power source) through the charger 4 in a period between the time �t1� and �t2� in FIG. 11. When the voltage of the storage unit 3 reaches a predetermined value, charging of the storage unit 3 is stopped in step S36.
Subsequently, in step S37, the fixing temperature detecting unit 8 detects the temperature T of the fixing roller 14 at the time of sheet passage. Then, the control unit 60 determines whether the temperature T of the fixing roller 14 is greater than or equal to the target temperature �T0� (T≧T0) in step S38. If the answer is NO in step S38, the control unit 60 switches ON the power supply from the storage unit 3 to the auxiliary heating members 1 b in step S39. Then, the control operation returns to reexecute step S37. If the answer is YES in step S38, the control unit 60 switches OFF the power supply from the storage unit 3 to the auxiliary heating members 1 b in step S40.
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