JP2006084914A - Fixing device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce flicker generation even when a fixing roll is equipped with a plurality of heaters and selective driving among them is carried out. <P>SOLUTION: In the fixing device 1 equipped with the fixing roll 2, a plurality of heating means 4 and 5 of heating it, a plurality of temperature detecting means 4 and 5 of detecting the temperature of the fixing roll 2, and a control means 8 of performing drive control over the plurality of heating means 4 and 5 according to detection results of the plurality of temperature detecting means 6 and 7, the control means 8 compares the difference between the detection results of the plurality of temperature detecting means 6 and 7 with previously set hysteresis temperature and performs selective drive switching between the plurality of heating means 4 and 5 according to the comparison result. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing device and a fixing method used in an electrophotographic copying machine, a printer device, a facsimile device, and the like.

Electrophotographic copying machines, printers, facsimile machines, etc. are equipped with a fixing device that heat-fixes the toner image formed on the recording paper with a fixing roll, but in order to maintain the high quality of the formed image It is necessary to keep the surface temperature of the fixing roll substantially constant. For this reason, the fixing device usually has a function of performing ON / OFF control of a heater for heating the fixing roll in accordance with the surface temperature of the fixing roll.
For example, as a fixing device, the surface temperature of the fixing roll is detected by a sensor, and on the basis of the detection result, ON / OFF control of a heater for heating the fixing roll is performed, so that the fixing roller has a predetermined fixing temperature. In general, a variation range from temperature can be reduced (see, for example, Patent Document 1).
In addition to reducing the fluctuation range of the surface temperature of the fixing roll, the fixing device includes a plurality of heaters in order to make the surface temperature uniform over the entire area of the fixing roll. In addition, there is also a control that performs ON / OFF control in common (for example, see Patent Document 2).

JP-A-9-54520 JP 2001-142544 A

  Incidentally, it is known that the fixing device has a problem of reducing the occurrence of flicker. If the voltage fluctuates frequently due to repeated ON / OFF of the heater, flicker ("brightness flickering feeling that humans feel") occurs in the lighting equipment in the environment room connected to the same power supply system as the heater Therefore, this is to suppress this as much as possible. For this reason, for example, in the fixing device disclosed in Patent Document 2, each of the plurality of heaters is turned on when the temperature of the fixing roll is equal to or lower than the first control temperature lower than the reference temperature, and is higher than the reference temperature. It has been proposed to reduce the degree of flicker that occurs by performing so-called hysteresis control, which is turned off when the temperature exceeds 2 control temperatures.

  However, in a fixing device having a plurality of heaters, when trying to make the surface temperature of the fixing roll uniform, ON / OFF is controlled independently for each heater and selectively turned ON / OFF between them. It is essential to switch between the two. Therefore, the uniform hysteresis control based on the first control temperature and the second control temperature as described above cannot perform selective ON / OFF switching with excellent responsiveness, and does not necessarily make the surface temperature of the fixing roll uniform. Is not always possible. On the other hand, if selective ON / OFF switching for each heater is frequently performed, the surface temperature of the fixing roll can be easily made uniform due to excellent responsiveness. However, the frequent switching control causes flicker. There is a risk of it.

  Therefore, the present invention is provided with a plurality of heaters, making it possible to realize flexible temperature management for the fixing roll such as uniform surface temperature and the like, and even in such a case, flicker generation can be reduced. It is an object of the present invention to provide a fixing device and a fixing method.

  The present invention is a fixing device devised to achieve the above object, and includes a fixing roll, a plurality of heating means for heating the fixing roll, and a temperature of the fixing roll heated by the heating means. A plurality of temperature detecting means for detecting, and a control means for performing drive control on the plurality of heating means based on detection results by the plurality of temperature detecting means, wherein the control means includes the plurality of temperature detecting means. The difference between the detection results is compared with a preset hysteresis temperature, and selective drive switching for the plurality of heating means is performed based on the comparison result.

  Further, the present invention provides a fixing method devised to achieve the above object, a fixing roll, a plurality of heating means for heating the fixing roll, and the fixing roll heated by the heating means. A fixing method used in a fixing device, comprising: a plurality of temperature detecting means for detecting temperature; and a control means for performing drive control on the plurality of heating means based on detection results by the plurality of temperature detecting means. In the selective drive switching for the plurality of heating means, the control means compares the difference between the detection results by the plurality of temperature detection means with a preset hysteresis temperature, and the comparison result The selective drive switching is performed based on the above.

  In the fixing device having the above-described configuration and the fixing method according to the above-described procedure, when performing selective driving switching with respect to the plurality of heating units, the difference between the detection results of the plurality of temperature detection units is compared with the hysteresis temperature. Yes. “Hysteresis temperature” is a temperature that is set to reduce drive switching between multiple heating means, and allows for drive switching based on the difference between the detection results of multiple temperature detection means while maintaining a predetermined condition. This is set to give a grace to the drive switching timing (for example, a condition specified by how the difference in detection results occurs). Therefore, according to the fixing device having the above-described configuration and the fixing method according to the above-described procedure, if a difference occurs in each detection result, the selective driving switching for each heating unit is not immediately performed to correct the difference, Comparison with the hysteresis temperature is performed, and if necessary, a delay specified from the hysteresis temperature is given, and then selective drive switching for each heating means is performed. That is, by giving a grace to the drive switching timing, it is possible to prevent the drive switching from being repeated frequently. In addition, after the grace period, selective drive switching for each heating means is performed, so that the difference in detection results between the temperature detection means is corrected through the drive switching.

  As described above, in the fixing device and the fixing method of the present invention, when a difference occurs between the detection results of the plurality of temperature detection means, the selective drive switching for each heating means is not performed immediately, but the difference and hysteresis are detected. By performing the drive switching based on the comparison result with the temperature, a delay can be given to the drive switching timing as necessary. Accordingly, even when a plurality of heaters are provided and selective drive switching is performed between them, frequent switching of the drive can be suppressed, and as a result, occurrence of flicker can be reduced. In addition, by selectively switching the drive between each heating means, the difference in the detection results at each temperature detection means is corrected, so flexible temperature management such as uniformizing the surface temperature of the fixing roll is realized. While being possible, the surface temperature can be maintained appropriately.

  Hereinafter, a fixing device and a fixing method according to the present invention will be described with reference to the drawings. First, the configuration of the fixing device according to the present invention will be described. FIG. 1 is a schematic diagram illustrating an example of a schematic configuration of a fixing device according to the present invention.

  As shown in the figure, the fixing device 1 described here includes a fixing roll 2 and a pressure roll 3 opposite to the fixing roll 2, and the recording paper is nipped and conveyed by these to form on the recording paper. The formed toner image is heat-fixed.

  For this purpose, the fixing roll 2 includes two heaters 4 and 5 as heating means for heating the fixing roll 2. Each of these heaters 4 and 5 has a different heating area. For example, each of the heaters 4 and 5 is arranged so as to extend along the axial direction of the fixing roll 2, but one heater (hereinafter referred to as “first heater”) 4 has a heating region in the fixing roll. 2, while the other heater (hereinafter referred to as “second heater”) 5 is arranged so that its heating region remains only in the vicinity of the central portion of the fixing roll 2. It is such a state. The vicinity of the central portion of the fixing roll 2, which is a heating area by the second heater 5, corresponds to an area through which all the recording papers of various sizes supported by the fixing device 1 pass. That is, the second heater 5 heats an area through which recording papers of various sizes pass in common. Note that the heaters 4 and 5 themselves may be heated by energization, as in the conventional case, and thus the description thereof is omitted here. In this example, the fixing roll 2 includes two heaters 4 and 5 as an example, but the number of built-in heaters may be three or more. Further, here, a case where recording sheets of various sizes pass between the fixing roll 2 and the pressure roll 3 with the central portion of the fixing roll 2 as a reference position is described as an example. Of course, the end may be a reference position. In that case, the second heater 5 is arranged near the end of the fixing roll 2.

  The fixing roll 2 is provided with two temperature sensors 6 and 7 as temperature detecting means for detecting the surface temperature of the fixing roll 2. Each of these temperature sensors 6 and 7 is disposed at a location corresponding to a heating area by each of the heaters 4 and 5. For example, one temperature sensor (hereinafter referred to as “center temperature sensor”) 6 is arranged near the center of the fixing roll 2 corresponding to the heating area by the second heater 5, while the other temperature is The sensor (hereinafter referred to as “end temperature sensor”) 7 is arranged on the end side of the fixing roll 2 so as not to correspond to the heating area by the second heater 5 but only to the heating area by the first heater 4. It has been, and so on. Note that the temperature sensors 6 and 7 themselves are the same as those in the prior art, and the description thereof is omitted here. In addition, here, the case where the number of the temperature sensors 6 and 7 is two corresponding to the number of the heaters 4 and 5 is given as an example, but there are three or more built-in heaters, and the heating area by each is also If it can be classified into three or more, three or more temperature sensors are provided corresponding to each heating region.

  Each of the heaters 4 and 5 and the temperature sensors 6 and 7 are electrically connected to the control means 8. The control means 8 comprises a combination of a CPU (Central Processing Unit) for executing a predetermined program, a ROM (Read Only Memory) for storing the predetermined program, a RAM (Random Access Memory) used as a work area for the CPU, and the like. Thus, by electrically connecting the heaters 4 and 5 and the temperature sensors 6 and 7, the temperature detection results of the temperature sensors 6 and 7 are received, and on the basis of the temperature detection results, the heaters 4 and 5 are received. 5, that is, heating ON / OFF control is performed.

However, in the control means 8, in addition to a temperature suitable for heat fixing of the toner image by the fixing roll 2 (hereinafter referred to as “heating target temperature”), a “hysteresis temperature” is preset and registered. When the temperature detection results of 6 and 7 are received, as will be described in detail later, the difference between these temperature detection results and the hysteresis temperature are compared, and selective drive switching for each heater 4 and 5 is performed based on the comparison result. Is supposed to do.
“Hysteresis temperature” is a temperature set to reduce the drive switching between the heaters 4 and 5, while enabling the drive switching based on the difference between the temperature detection results by the temperature sensors 6 and 7. , One set in order to give a grace to the drive switching timing under a predetermined condition (for example, a condition specified by the difference in detection result). Such a hysteresis temperature may be specified empirically through experiments, simulations, or the like in accordance with the specifications of a system (such as a copying machine) in which the fixing device 1 is mounted, and an interface panel electrically connected to the control means 8 ( However, setting registration to the control means 8 may be performed by operating (not shown).
“Selective drive switching” for the heaters 4 and 5 refers to heating when the heaters 4 and 5 are selectively driven to heat the fixing roll 2. This refers to switching the selection state of the heaters 4 and 5. Therefore, the case of starting and ending heating of the fixing roll 2 by all the heaters 4 and 5 does not correspond to the selective drive switching referred to here.

  Next, an example of a control operation in the fixing device 1 configured as described above, that is, a fixing method according to the present invention will be described. FIG. 2 is a flowchart illustrating an example of a control operation example in the fixing device according to the present invention.

  In the fixing device 1, the control unit 8 gives a drive instruction to the heaters 4 and 5 in response to a start instruction from a system in which the fixing device 1 is mounted, and starts heating the fixing roll 2. At this time, in principle, the control means 8 drives only the first heater 4 to turn it on, and heats the entire area of the fixing roll 2. And after a heating start, the control means 8 always monitors the temperature detection result by each temperature sensor 6 and 7. FIG.

As a result of the monitoring, if the temperature of the area through which all the recording papers of various sizes pass, that is, the temperature detection result by the central temperature sensor 6 becomes equal to or higher than the preset heating target temperature (step 11- YES, the following step is abbreviated as “S”), and since the control means 8 does not require any further heating, both the first heater 4 and the second heater 5 are turned off. Drive instruction.
On the other hand, when the temperature detection result by the central temperature sensor 6 is less than the heating target temperature (S11-NO), since further heating is necessary, the control means 8 drives the heaters 4 and 5 at that time. The subsequent drive pattern is determined according to the pattern, and either the first heater 4 or the second heater 5 is selectively turned on with the determined drive pattern, and heating of the fixing roll 2 is continued.

  Therefore, the control means 8 first determines whether or not the first heater 4 is in an ON state (S12). If the first heater 4 is in the ON state (S12-YES), the temperature detection result by the central temperature sensor 6 and the temperature detection result by the end temperature sensor 7 are subsequently compared (S13). As a result of this comparison, if the vicinity of the center of the fixing roll 2 is lower than the vicinity of the end (S13-YES), the temperature near the center of the fixing roll 2 has decreased due to the passage of recording paper or the like. Therefore, in order to compensate for the temperature drop, the control means 8 drives the second heater 5 having only the vicinity of the central portion of the fixing roll 2 as a heating region to be in the ON state, and the first heater 4 Is turned OFF, and a drive instruction of “Pattern 2” in the figure is given. On the other hand, if the temperature near the center of the fixing roll 2 is equal to or higher than the temperature near the end (S13—NO), the heating of the entire area of the fixing roll 2 is insufficient. Is driven to turn on, and the entire area of the fixing roll 2 is heated.

  If the first heater 4 is in the OFF state (S12-NO), then the control means 8 presets the temperature detection result by the central temperature sensor 6 to the temperature detection result by the end temperature sensor 7. The hysteresis temperatures are added and compared (S14). That is, instead of directly comparing the temperature near the center of the fixing roll 2 and the temperature near the end, the difference between them is compared with the hysteresis temperature. If the first heater 4 is in the OFF state, the previous state is out of the basic heating state, so that the fixing roll 2 is not immediately reheated but given a grace period specified by the hysteresis temperature. After that, the fixing roll 2 is reheated, that is, selective drive switching for the heaters 4 and 5 is performed.

  As a result of this comparison, if the temperature near the center of the fixing roll 2 does not satisfy the added value of the temperature near the end and the hysteresis temperature (S14-NO), the center of the fixing roll 2 is caused by the passage of the recording paper or the like. Since it is conceivable that the temperature in the vicinity has decreased, the control means 8 drives the second heater 5 having only the vicinity of the central portion of the fixing roll 2 as a heating region to make up for the decrease in temperature. A drive instruction of “Pattern 2” in the figure is given to turn the first heater 4 off while turning the state on. On the other hand, if the temperature near the center of the fixing roll 2 is equal to or higher than the sum of the temperature near the end and the hysteresis temperature (YES in S14), the entire heating area of the fixing roll 2 is insufficiently heated. The control means 8 drives only the first heater 4 to be in the ON state, and gives a driving instruction of “Pattern 3” in the drawing to heat the entire area of the fixing roll 2.

Next, a specific example of temperature control by the control operation of the above procedure will be described with reference to FIG. 3A shows a specific example of the temperature change in the fixing roll 2, and FIG. 3B shows a specific example of selective drive switching for the heaters 4 and 5 corresponding to the temperature change. c) show specific examples of conventional drive switching as comparative examples.
Here, the case where the heating target temperature is set to 195 ° C. and the hysteresis temperature is set to 1 ° C. is taken as an example.

  As shown in FIGS. 3A and 3B, when the temperature detection results by the temperature sensors 6 and 7 are both 191 ° C. and less than the heating target temperature (S21), the control means 8 Only the first heater 4 is driven to be in the ON state, and a “pattern 3” driving instruction for heating the entire area of the fixing roll 2 is given.

  Thereafter, when the temperature detection result at the end temperature sensor 7 becomes higher than the temperature detection result at the center temperature sensor 6 (S22), the temperature near the center of the fixing roll 2 becomes lower than the temperature near the end. Therefore, the control means 8 drives the “pattern 2” to drive the second heater 5 having only the vicinity of the center portion of the fixing roll 2 as a heating region to turn on and turn off the first heater 4. Give instructions and switch drive. As a result, the temperature detection results by the temperature sensors 6 and 7 once become the same (S23), both rise, and the temperature near the center of the fixing roll 2 is higher than the temperature near the end. (S24).

  At this time, the control means 8 compares the difference between the temperature detection results of the temperature sensors 6 and 7 with the hysteresis temperature, and the temperature detection result of the central temperature sensor 6 is more than the temperature detection result of the end temperature sensor 7. When the hysteresis temperature becomes higher than 1 ° C. set as the hysteresis temperature, the control means 8 gives a drive instruction of “Pattern 3” to drive only the first heater 4 and turn it on to heat the entire area of the fixing roll 2 and drive it. Switch. That is, the drive switching is not performed when the temperature detection results by the temperature sensors 6 and 7 become the same (see FIG. 3C), but the drive switching is performed after giving a margin specified by the hysteresis temperature. It is. Even when the temperature detection result of the end temperature sensor 7 becomes higher than the temperature detection result of the central temperature sensor 6 due to this heating (S25, S26), the control means 8 is similar to the above-described case. The drive is switched from “Pattern 3” to “Pattern 2”.

  And when the temperature detection result in the center temperature sensor 6 reaches heating target temperature (S27), since the control means 8 does not need the further heating, both the 1st heater 4 and the 2nd heater 5 are used. A drive instruction of “Pattern 1” to be turned off is given to perform drive switching. Thereby, the temperature detection results by the temperature sensors 6 and 7 are lowered from the heating target temperature because the heaters 4 and 5 are not heating (S28). In that case, the control means 8 performs drive switching from “Pattern 1” to “Pattern 3” in order to heat the entire area of the fixing roll 2 again.

  As described above, in the fixing device 1 described in the present embodiment, when the control unit 8 selectively switches the driving of the heaters 4 and 5, the control unit 8 detects the detection results of the temperature sensors 6 and 7. And the hysteresis temperature are compared. That is, when a difference occurs in each detection result, instead of immediately performing selective drive switching for each heater 4 and 5 to correct the difference, the difference is compared with the hysteresis temperature, and if necessary, the hysteresis is detected. After giving the time specified from the temperature, selective drive switching for the heaters 4 and 5 is performed. Therefore, even when a plurality of heaters 4 and 5 are provided and selective drive switching is performed between them, frequent switching of the drive can be suppressed. This is also clear from a comparison between the specific example of FIG. 3B and the specific example of FIG. In addition, after the grace period, selective drive switching for the heaters 4 and 5 is performed, so that the difference in detection results between the temperature sensors 6 and 7 is corrected through the drive switching.

  Therefore, according to the fixing device 1 of the present embodiment, by providing the fixing roll 2 with the plurality of heaters 4 and 5, flexible temperature management such as uniform surface temperature of the fixing roll 2 can be realized. The surface temperature can be appropriately maintained, and even in this case, selective ON / OFF drive switching for each heater 4 and 5 can be suppressed, and as a result, the occurrence of flicker can be reduced. Can do.

  In addition, as in the fixing device 1 of the present embodiment, the heating regions of the heaters 4 and 5 are different from each other, and the temperature sensors 6 and 7 are disposed at respective locations corresponding to the heating regions. If the distribution of the surface temperature of the fixing roll 2 varies along the axial direction, the variation can be corrected by selectively switching the driving of the heaters 4 and 5. It will be able to plan. Therefore, it is possible to form a good image on any size recording sheet while ensuring versatility as a fixing device, for example, corresponding to various size recording sheets.

  In addition, although this embodiment demonstrated the suitable Example of this invention, this invention is not limited to the content. In particular, the number and arrangement of the heaters 4 and 5 and the temperature sensors 6 and 7 are not limited to the contents given as examples in the present embodiment, and are appropriately changed without departing from the scope of the invention. It is possible.

FIG. 2 is a schematic diagram illustrating an example of a schematic configuration of a fixing device according to the present invention. 6 is a flowchart illustrating an example of a control operation example in the fixing device according to the present invention. It is explanatory drawing which shows the specific example of the temperature control in the fixing device which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fixing device, 2 ... Fixing roll, 3 ... Pressure roll, 4 ... 1st heater, 5 ... 2nd heater, 6 ... Center temperature sensor, 7 ... End part temperature sensor, 8 ... Control means

Claims (3)

A fixing roll;
A plurality of heating means for heating the fixing roll;
A plurality of temperature detecting means for detecting the temperature of the fixing roll heated by the heating means;
And a control means for performing drive control on the plurality of heating means based on detection results by the plurality of temperature detection means,
The control means compares the difference between the detection results of the plurality of temperature detection means with a preset hysteresis temperature, and performs selective drive switching for the plurality of heating means based on the comparison result. A fixing device characterized by that. The plurality of heating means have different heating areas,
The fixing device according to claim 1, wherein the plurality of temperature detection units are disposed at respective locations corresponding to heating regions by the plurality of heating units. A fixing roll;
A plurality of heating means for heating the fixing roll;
A plurality of temperature detecting means for detecting the temperature of the fixing roll heated by the heating means;
A fixing method used in a fixing device including a control unit that performs drive control on the plurality of heating units based on detection results of the plurality of temperature detection units,
In performing selective drive switching for the plurality of heating means, the control means compares the difference between the detection results of the plurality of temperature detection means with a preset hysteresis temperature, and determines the comparison result. A fixing method characterized in that the selective drive switching is performed based on this.

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