JP2004004332A - Method for controlling temperature of fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain excellent fixing performance for a long time and to make the power consumption for preheating a 1st roller 1 less when a fixing device that comprises a 1st roller 1 whose surface is heated by a heat roller 5 and which is relatively thin and small in heat accumulation amount and a 2nd roller 2 which is heated by an internal heat source 3, relatively thick and large in heat accumulation amount and also has its power consumption suppressed in a standby mode is brought under electrification control. <P>SOLUTION: Although the temperature of the 1st roller 1 which comes into contact with a toner is set higher than the temperature of the 2nd roller 2 which heats the reverse side of a paper sheet before, the temperature of the 2nd roller 2 is set as usual and the temperature of the 1st roller 1 is set lower than before. The 1st roller 1 which is small in heat accumulation amount is therefore speedily heated by the heat roller 5 to reach a sufficiently high temperature before the paper sheet is fed and also speedily recovers even when heat is absorbed by the fed paper sheet. Thus, the power consumption in a standby mode can be made less. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fixing device suitably implemented in an electrophotographic image forming apparatus.
[0002]
[Prior art]
In the electrophotographic image forming apparatus, the unfixed toner image is transferred between a pair of rollers, a heating roller and a pressure roller, so that the unfixed toner is melted. The fixing process is performed by fixing. The fixing device is a portion of the image forming apparatus which consumes the largest amount of power, and it is effective to suppress the power consumption of the fixing device in response to recent demand for power saving.
[0003]
Therefore, in recent years, in a fixing device, a “thin fixing device” has been developed. Thin fixation means that even if the thickness of the conventional heating roller is reduced and the temperature of the roller during standby is set low for power saving, the heat storage amount due to the thinning is small, and the fixing time is short. It is designed to be able to rise to a specified fixing temperature. However, in the thin-wall fixing, as described above, since the heating roller is too thin, the amount of heat stored in the roller itself is small, and during the fixing process of one sheet of printing paper or during continuous printing, the surface temperature of the heating roller is reduced. There is a problem that "insufficient fixing" (so-called low-temperature offset) is caused by the shortage.
[0004]
In order to solve such a problem, for example, in Japanese Patent Application Laid-Open No. Hei 9-31575, a heat capacity complementer is arranged in contact with the back surface of a heating roller in accordance with a heat source for heating, and the amount of heat taken by a passing sheet is determined. Is proposed. However, such a heat capacity complement is given a necessary amount of heat by the heat source in advance, and radiates heat when the device is not operating. In other words, even though the amount of heat can be replenished when fixing the paper, the increase in the amount of heat stored by the heat capacity complementer impairs the power saving effect that is the original purpose of thin fixing. .
[0005]
Therefore, in order to solve such a problem, another conventional technology proposes a fixing device as shown in FIG. This fixing device has first and second rollers 1 and 2, and a heat source 3 realized by a heater lamp or the like is disposed inside a second roller 2 for heating the back side of a sheet. Although it is the same as the fixing device, the first roller 1 is different from the conventional one in that the first roller 1 has the thin-walled structure and the heat source 4 employs an external heating method arranged outside the first roller 1. Is a point. The heat source 4 is provided inside the heating roller 5, and when the heating roller 5 rotates in close contact with the first roller 1, heat from the heat source 4 propagates to the surface of the first roller 1. Then, the surface is heated.
[0006]
As shown in FIG. 1, a part of the first roller 1 is such that the thin heat storage section 1a is attached to a core section 1c via a heat insulation section 1b. The portion 1c does not contribute to the accumulation of heat for fixing. In other words, when the heat storage section 1a is heated by the heating roller 5, the heat propagates to the heat insulating section 1b and the core section 1c, so that heat storage and heat dissipation are rare, and the heat storage section 1a rises instantaneously. Warm up. In this way, by heating the first roller 1 that heats the front side of the sheet in contact with the unfixed toner from the front side, the amount of heat necessary for continuous processing can be continuously supplied even with a small amount of heat storage. It is supposed to be.
[0007]
[Problems to be solved by the invention]
However, in the above-described prior art, similarly to the prior art in which the heat source 4 is provided in the first roller 1, the temperature of the preheating during standby is such that the first surface of the paper that contacts the unfixed toner is heated. The roller 1 is controlled to be higher than the second roller 2 that heats the back surface of the sheet, and the fact is that the effect of power saving by the thinning is not fully utilized.
[0008]
FIG. 6 shows a general temperature control method for printing. Hereinafter, a case where this temperature control is applied to the first roller 1 will be described. FIG. 6A is a graph showing a change in the surface temperature of the first roller 1 with time, and FIG. 6B is a waveform diagram showing a control state of the heat source 4 with time. When the power is turned on at time t0, the power supply to the heat source 4 is started. When the surface temperature reaches a predetermined set temperature T1, the power supply is temporarily stopped at the time t1, and the warm-up is completed. However, even when the energization is stopped, the surface temperature rises, though more slowly, than at the time of the warm-up due to the residual heat of the heat source 4 or the like.
[0009]
In this state, at time t2, the actual printing process in response to the print request is started, and when the sheet passing is started at time t3, the surface temperature starts to decrease. When the temperature falls below the set temperature T1 at time t4, the power supply to the heat source 4 is restarted. Thereafter, even when the energization is continued, the surface temperature gradually decreases while repeating the temperature decrease due to the passage of the sheet indicated by reference numeral W1 and the temperature increase due to the sheet interval indicated by the reference numeral W2. During this time, if the surface temperature does not exceed the set temperature T1, the heat source 4 is continuously energized as shown in FIG. Then, when the temperature falls below the lower limit value T2 at time t5, a low-temperature offset at which the toner peels off from the sheet occurs, resulting in poor fixing.
[0010]
As described above, when the general temperature control method is applied to the first roller 1 having a small heat storage amount, there is a problem that uniform fixing properties cannot be obtained from the first page to the last page. In particular, for the sheet immediately after the warm-up (the third sheet in FIG. 6), the fixing lower limit value T2 cannot be maintained until the rear end of the sheet passes.
[0011]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a temperature control method of a fixing device that can obtain good fixing performance over a long period of time and can reduce power consumption for preheating the first roller during standby. It is to be.
[0012]
[Means for Solving the Problems]
The temperature control method for a fixing device according to the present invention includes a first roller having a surface heated from an outer peripheral portion by a heating unit, and a second roller having a heating unit therein. In the temperature control method of the fixing device, in which the unfixed toner image is transferred and the unfixed toner image is transferred to melt the unfixed toner and fix the toner image on the sheet, the surface of the sheet that comes into contact with the toner is set to a standby state. The temperature of the first roller to be heated is lower than the temperature of the second roller to heat the back side of the sheet.
[0013]
According to the above configuration, the surface is heated from the outer peripheral portion by the heating means, the first roller is relatively thin and has a small heat storage amount, and the first roller is heated by the internal heating means and is relatively thick and has a large heat storage amount. In performing the energization control of the fixing device including the second roller, the temperature of the first roller in contact with the toner in the conventional fixing device during standby is controlled by the temperature of the first roller that heats the back side of the sheet. In the present invention, the second roller is set to be the same as the conventional one, and the first roller is set to be lower than the conventional one.
[0014]
Therefore, even when continuous paper passing is performed, the temperature of the second roller having a large heat storage amount does not readily drop to the fixing lower limit value, and the first roller having a small heat storage amount is quickly heated by the heating means, and the temperature of the first roller before the paper passing is increased. The temperature rises to a sufficiently high level, and it recovers quickly even if heat is removed by paper passing. Thus, good fixing performance can be obtained over a long period of time, and power consumption for preheating the first roller during standby can be reduced.
[0015]
In the temperature control method for a fixing device according to the aspect of the invention, the temperature of the second roller may be determined based on an amount of heat for warming the sheet for the fixing when the sheet is passed, and a rotation amount in close contact with the first roller when the sheet is not passed. Thus, the first roller is controlled based on the amount of heat that warms the surface of the first roller.
[0016]
According to the above configuration, as described above, in the conventional fixing device, the temperature of the first roller that contacts the toner is set to be equal to or higher than the temperature of the second roller that heats the back side of the sheet. In this case, the temperature of the second roller is set higher, so that the two rollers rotate in close contact with each other, so that heat is transmitted from the second roller to the first roller. Therefore, by controlling not only the amount of heat for warming the sheet when the second roller passes the paper but also the amount of heat for heating the first roller when the second roller is not passing the paper, the temperature of the second roller during the standby state can be further increased. It can be controlled appropriately.
[0017]
Therefore, good fixing performance can be obtained with a necessary minimum amount of preheating.
[0018]
Still further, the temperature control method for a fixing device of the present invention includes a first roller having a surface heated from the outer peripheral portion by a heating unit, and a second roller having a heating unit therein, and forming a pair. The unfixed toner image is transferred between the rollers, so that the unfixed toner is melted and fixed on the sheet. The disposed heating means is a heat source roller having a heat source therein and rotating in close contact with the first roller. When a print request is made, the heat source roller is energized continuously up to a preset number of prints. After the set number of sheets, the temperature is controlled based on the detection result of the temperature sensor arranged facing the surface of the first roller.
[0019]
According to the above configuration, when the heating means of the first roller is constituted by a heat source roller, the heat source roller also stores heat. Therefore, when a printing request is first made, the detection result of the temperature sensor at that time is set. Regardless of whether or not the temperature is exceeded, the process proceeds to continuous energization, and prepares for a subsequent temperature drop due to heat absorption of the sheet.
[0020]
However, if continuous energization is continued, the temperature of the first roller may significantly exceed the set temperature between sheets, depending on the sheet size, the ambient temperature, and the like. For this reason, after the predetermined number of printed sheets has elapsed, the normal temperature control is performed in response to the sensor output, whereby uniform fixing properties can be obtained from the first page to the last page.
[0021]
Further, the temperature control method of the fixing device of the present invention includes a first roller having a surface heated from the outer peripheral portion by a heating unit, and a second roller having a heating unit inside, and forming a pair of these rollers. In the temperature control method of the fixing device, in which the unfixed toner image is transferred between the rollers to melt the unfixed toner and fix the unfixed toner on the sheet, the sheet may face the surface of the first roller. In performing the temperature control based on the detection result of the disposed temperature sensor, each operation mode of the printing mode, the standby mode and the energy saving mode is set, and the set temperature in each operation mode is set as the printing mode> the standby mode> the energy saving mode. It has a mode relationship.
[0022]
According to the above configuration, in performing the temperature control based on the detection result of the temperature sensor, conventionally, the operation mode is a printing mode and an energy saving mode during a long standby time. , A new standby mode is added.
[0023]
Therefore, in the printing mode and the energy saving mode alone, since the time has not passed much since the previous printing process, and when the above-described temperature control is started in the printing mode in which the roller temperature is high, the set temperature is set by the paper passing. When the energization is started after the temperature drops below, the continuous energization time is shortened and the fixability is not stable.On the other hand, if the standby mode is added and continuous energization is started from the standby mode where the roller temperature is low at the start of printing Since the continuous energizing time can be secured long, the fixability can be stabilized.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
One embodiment of the present invention will be described below with reference to FIGS.
[0025]
A fixing device to which the present invention can be applied is configured as shown in FIG. 1 described above, and has a first roller 1 whose surface is heated from an outer peripheral portion by a heating roller 5 having a heat source 4 therein, A second roller 2 having a heat source 3, and the unfixed toner is melted by passing the paper 6 on which the unfixed toner image is transferred between the pair of rollers 1 and 2, The fixing device is fixed on the paper 6. Further, the first roller 1 is configured such that the thin heat storage section 1a is attached to the core section 1c via the heat insulating section 1b. Temperature sensors 7 and 8 for controlling the temperature, which will be described later, face the surfaces of the rollers 1 and 2.
[0026]
It should be noted that, in the present invention, during standby, the temperature of the second roller 2 having a relatively large heat storage amount is the same as the conventional one, and the temperature of the first roller 1 whose heat storage amount is relatively small and instantaneously rises. Is lower than the temperature of the second roller 2.
[0027]
Therefore, even if continuous paper passing is performed, the temperature of the second roller 2 having a large heat storage amount does not readily drop to the fixing lower limit value, and the first roller 1 having a small heat storage amount is quickly heated by the heating roller 5, It rises to a sufficient temperature before paper passing, and recovers quickly even if heat is taken away by paper passing. Thus, good fixing performance can be obtained over a long period of time, and power consumption for preheating the first roller 1 during standby can be reduced.
[0028]
Specifically, in consideration of the fact that the heat source is turned on in the sheet passing state, the heat storage amount of the conventionally used thick fixing roller is set to the number of sheets that can be input to the operation panel, for example, 99 sheets in A4 format. It has become. On the other hand, in the first roller 1 of the present invention, although it depends on the thickness of the heating roller 5 (usually 1 mm or less), it is about 2 to 3 sheets in terms of A4, and It can be understood that the power consumption for the above can be significantly reduced.
[0029]
In addition, as described above, in response to the temperature of the second roller 2 during standby being higher than the temperature of the first roller 1, the temperature of the second roller 2 is changed as shown in FIG. As shown in FIG. 2, the amount of heat Q1 for warming the paper 6 for the fixing when the paper is passed and the rotation of the first roller 1 in close contact with the first roller 1 when the paper is not passed as shown in FIG. The control is based on the heat quantity Q2 for warming the surface of the first roller 1. 2A, the amount of heat by which the first roller 1 warms the toner and the paper 6 for fixing is Q3.
[0030]
Therefore, the temperature of the second roller 2 during standby can be more appropriately controlled, and good fixing performance can be obtained with a necessary minimum preheating amount. Specifically, as described above, when the actual heat storage amount of the first roller 1 is about 2 to 3 sheets in terms of A4, the propagation from the second roller 2 causes It can be increased to about 10 to about 10 sheets, and good fixing performance can be obtained for a long time.
[0031]
FIG. 3 is a diagram showing a method of controlling the temperature of the first roller 1 at the time of printing according to an embodiment of the present invention. FIG. 3A is a graph showing a change in the surface temperature of the first roller 1 with time, and FIG. 3B is a waveform diagram showing a control state of the heat source 4 with time. When the power is turned on at time t0, the power supply to the heat source 4 is started, and when the surface temperature detected by the temperature sensor 7 reaches a predetermined set temperature T1, the power supply is temporarily stopped at the time t1, Warm-up is completed. However, even when the energization is stopped, the surface temperature rises, though more slowly, than at the time of the warm-up due to the residual heat of the heat source 4 or the like.
[0032]
In this state, when the actual printing process according to the print request is started at time t2, in the present embodiment, regardless of whether the detection result of the temperature sensor 7 at that time t2 exceeds the set temperature T1. Instead, the operation is shifted to continuous energization, and preparation is made for a subsequent temperature drop due to heat absorption of the paper 6. Therefore, even if the continuous energization is started from the time t2 and the sheet temperature is started from the time t3 and the surface temperature starts decreasing, the temperature rise before the sheet feeding does not easily lower the fixing lower limit temperature T2.
[0033]
However, if continuous energization is continued, the temperature of the first roller 1 may greatly exceed the set temperature in the space W2 between the paper W1 and the paper W1 depending on the paper size and the ambient temperature. There is. For this reason, after the preset number of prints has elapsed, the process proceeds to normal temperature control based on the detection result of the temperature sensor 7 and the set temperature T1 (in FIG. 3, due to space limitations, the set number of prints is used). Are shown only within
[0034]
On the other hand, when the temperature control of the first roller 1 is performed based on only the set temperature T1 as in the related art, the time of the continuous energization becomes short, and the fixing property becomes unstable. The control result in FIG. 6 is indicated by a broken line in FIG. In this way, uniform fixability can be obtained from the first page to the last page.
[0035]
FIG. 4 is a longitudinal sectional view showing an example of an image forming apparatus to which the present invention is applied. The image forming apparatus generally includes a scanner unit 11 and a printer unit 12. The scanner section 11 has a document table 13 made of transparent glass or the like on the upper surface, and a scanner optical system 14 is arranged below the document table 13. The scanner optical system 14 includes an exposure light source 15 for irradiating light on a document placed on the document table 13, a plurality of mirrors 16, 17, 18 for guiding reflected light from the document, and the mirrors 16 to 18. An imaging lens 19 for condensing the reflected light guided by 18 and a photoelectric conversion element (CCD) 20 for photoelectrically converting the light passing through the imaging lens 19 are provided.
[0036]
The document image data read by the CCD 20 is given to the printer unit 12 and subjected to image processing. Then, the laser image is irradiated from a laser scanning unit (LSU) 21 as laser light onto the surface of the photoreceptor 22, and an electrostatic latent image is formed. An image is formed. The photoconductor 22 has a drum shape that is driven to rotate in the direction of an arrow 23. Around the photoconductor 22, from the irradiation point of the laser light, along the rotation direction of the photoconductor 22, A developing device 24 for developing the electrostatic latent image into a visible image with toner, a transfer charger 25 for transferring the toner image on the photoreceptor 22 to paper, a static eliminator 26 for removing the charge of the photoreceptor 22 after the transfer, and A cleaning unit (not shown), a main charger 27 for charging the photoconductor 22 to a predetermined potential, the LSU 21 and the like are arranged in this order.
[0037]
A paper tray 28 is provided below the printer unit 12, and paper is fed from the paper tray 28 and an external manual feed tray 29, and is electrostatically applied to the paper at a nip between the photoconductor 22 and the transfer charger 25. The latent image is transferred, and the sheet after the transfer is fixed by a fixing device including the rollers 1 and 2, and is discharged from a discharge roller 30 onto a discharge tray 31.
[0038]
Another embodiment of the present invention will be described below with reference to FIG.
[0039]
FIG. 5 is a diagram showing a temperature control method for the first roller 1 according to another embodiment of the present invention. The fixing device to which this temperature control is applied can also be realized with the configuration as shown in FIG. FIG. 5A is a graph showing a change in the surface temperature of the first roller 1 with the lapse of time, similarly to FIG. 3A described above, and FIG. FIG. 3 is a waveform diagram showing a control state of the heat source 4 with time similarly. In FIG. 5, the same portions as those in FIG. 3 described above are denoted by the same reference numerals, and description thereof will be omitted.
[0040]
It should be noted that for the temperature control, a standby mode is newly provided in addition to the conventional print mode and the energy saving mode during a long standby. And the set temperature in each operation mode,
Printing mode> Standby mode> Energy saving mode
Are set to have the following relationship.
[0041]
That is, although not shown in FIG. 5, the set temperature of the energy saving mode and the set temperature of the print mode corresponding to the set temperature T1 are set in the same manner as in the related art, and in the present embodiment, the fixing lower limit value T2 Is newly set as the set temperature of the standby mode. Note that the set temperature in the standby mode does not have to match the fixing lower limit value T2, as long as the relationship between the set temperatures satisfies the above equation. Reference T3 is a fixing upper limit value.
[0042]
When the power is turned on at time t0, the power supply to the heat source 4 is started. When the surface temperature detected by the temperature sensor 7 reaches the fixing lower limit value T2, the power supply is temporarily stopped at the time t1. Warm-up is completed. However, even when the energization is stopped, the surface temperature is gradually increased due to the residual heat of the heat source 4 or the like at the time of the warm-up (in FIG. 5, the time until the subsequent print request is long, Further, since the temperature is lower than the set temperature T1 in the print mode, the temperature is easily cooled, and thereafter, the temperature starts decreasing.)
[0043]
In this state, when the actual printing process is started at time t2, the target of the temperature control is switched to the set temperature T1 in the print mode, and the temperature control is set in advance in the same manner as the temperature control in FIG. After continuous energization until the number of printed sheets elapses, the process proceeds to normal temperature control based on the detection result of the temperature sensor 7 and the set temperature T1 (FIG. 5 shows only the set number of sheets within the set number of sheets due to space limitations). Absent). When a predetermined time elapses after the printing process ends, the target of the temperature control is switched to the set temperature of the energy saving mode lower than the fixing lower limit value T2.
[0044]
Accordingly, in the printing mode and the energy saving mode alone, when the time has not passed much since the previous printing process, and when the above-described temperature control is started in the printing mode in which the roller temperature is high, the time shown in FIG. As indicated by t4, the energization is started after the temperature has fallen below the set temperature due to the paper passing, and the continuous energization time is shortened to stabilize the fixing property. By starting continuous energization from the standby mode where the power is low, a long time for the continuous energization can be secured, and the fixing property can be stabilized.
[0045]
【The invention's effect】
As described above, according to the temperature control method of the fixing device of the present invention, the surface is heated from the outer peripheral portion by the heating means, and the first roller is relatively thin and has a small heat storage amount, and is heated by the internal heating means. In controlling the energization of the fixing device including the second roller having a large thickness and a large amount of heat storage, the temperature at the time of standby and the temperature of the first roller in contact with the toner in the conventional fixing device are set to the back surface of the sheet. The temperature of the second roller for heating the side is set to be equal to or higher than the temperature of the second roller. However, the second roller is changed to the conventional one, and the first roller is set to be lower than the conventional one.
[0046]
Therefore, even when continuous paper passing is performed, the temperature of the second roller having a large heat storage amount does not readily drop to the fixing lower limit value, and the first roller having a small heat storage amount is quickly heated by the heating means, and It rises to a sufficient temperature before, and recovers quickly even if heat is removed by passing paper. Thus, good fixing performance can be obtained over a long period of time, and power consumption for preheating the first roller during standby can be reduced.
[0047]
Further, as described above, the temperature control method of the fixing device according to the present invention is such that the temperature of the roller during standby is such that the temperature of the first roller that heats the front surface of the paper is the temperature of the second roller that heats the rear surface of the paper. In response to the temperature being set lower than the temperature, the temperature of the second roller is adjusted not only by the amount of heat for the second roller to heat the sheet for fixing when the sheet is passed, but also by the first roller when the sheet is not passed. Is controlled based on the amount of heat that warms the surface of the first roller by rotating in close contact with the first roller.
[0048]
Therefore, the temperature of the second roller during standby can be more appropriately controlled, and good fixing performance can be obtained with a necessary minimum amount of preheating.
[0049]
Furthermore, as described above, the temperature control method of the fixing device according to the present invention is characterized in that the surface is heated from the outer peripheral portion by the heating means, the first roller is relatively thin and has a small heat storage amount, and the heating is performed by the internal heating means. When controlling the energization of the fixing device constituted by the second roller having a relatively large thickness and a large amount of heat storage, if the heating means of the first roller is constituted by a heat source roller, the heat source roller also has a heat storage roller. Therefore, when a print request is first made, regardless of whether the detection result of the temperature sensor at that time exceeds the set temperature, the process proceeds to continuous energization, and thereafter, when a preset number of printed sheets elapses, Hereinafter, normal temperature control is performed in response to the sensor output.
[0050]
Therefore, uniform fixability can be obtained from the first page to the last page.
[0051]
Further, as described above, in the temperature control method of the fixing device of the present invention, the surface is heated from the outer peripheral portion by the heating means, and the first roller is relatively thin and has a small heat storage amount, and is heated by the internal heating means. Conventionally, in controlling the energization of a fixing device including a relatively thick second roller having a large heat storage amount, the operation modes are a printing mode and an energy saving mode during a long standby time. A new standby mode is newly added, and the set temperature in each operation mode is set to the relation of print mode> standby mode> energy saving mode.
[0052]
Therefore, in the print mode and the energy saving mode alone, if the time has not passed much since the previous print processing and the temperature control described above is started in the print mode in which the temperature of the roller is high, the setting by paper passing is performed. The energization starts after the temperature falls, and the continuous energization time is shortened and the fixability is unstable.On the other hand, a standby mode has been added, and continuous energization starts from the standby mode where the roller temperature is low at the start of printing By doing so, it is possible to secure a long time for the continuous energization and to stabilize the fixing property.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a fixing device to which the present invention can be applied.
FIG. 2 is a diagram for explaining how heat is transmitted between two rollers during printing.
FIG. 3 is a diagram showing a method of temperature control during printing according to an embodiment of the present invention.
FIG. 4 is a longitudinal sectional view illustrating an example of an image forming apparatus to which the present invention is applied.
FIG. 5 is a diagram showing a temperature control method according to another embodiment of the present invention.
FIG. 6 is a diagram showing a conventional temperature control method.
[Explanation of symbols]
1 First roller
1a Heat storage unit
1b Insulation section
1c Core part
2 Second roller
3, 4 heat source (heating means)
5. Heating roller (heating means)
6 paper
7,8 Temperature sensor
11 Scanner section
12 Printer section
13 Platen
14 Scanner optical system
21 LSU
22 Photoconductor
24 Developing device
25 Transfer Charger
26 Static eliminator
27 Main charger

Claims (4)

A sheet having an unfixed toner image transferred between a pair of rollers, having a first roller whose surface is heated from the outer peripheral portion by a heating unit, and a second roller having a heating unit therein. In the temperature control method of the fixing device, the unfixed toner is melted by passing the toner, and the toner is fixed on the sheet.
A temperature control method for a fixing device, comprising: setting a temperature of a first roller for heating a front surface of a sheet in contact with the toner to be lower than a temperature of a second roller for heating a rear surface of the sheet during standby. The temperature of the second roller is determined by the amount of heat for warming the sheet for the fixing when the sheet is passed, and the amount of heat for heating the surface of the first roller by rotating in close contact with the first roller when the sheet is not passed. The method according to claim 1, wherein the control is performed based on the following. A sheet having an unfixed toner image transferred between a pair of rollers, having a first roller whose surface is heated from the outer peripheral portion by a heating unit, and a second roller having a heating unit therein. In the temperature control method of the fixing device, the unfixed toner is melted by passing the toner, and the toner is fixed on the sheet.
The heating means disposed on the outer periphery of the first roller is a heat source roller having a heat source therein and rotating in close contact with the first roller. The heat source roller is set in advance when a printing request is made. The temperature of the fixing device is controlled based on a detection result of a temperature sensor arranged facing the surface of the first roller after the set number of sheets. Control method. A sheet having an unfixed toner image transferred between a pair of rollers, having a first roller whose surface is heated from the outer peripheral portion by a heating unit, and a second roller having a heating unit therein. In the temperature control method of the fixing device, the unfixed toner is melted by passing the toner, and the toner is fixed on the sheet.
In performing the temperature control based on the detection result of the temperature sensor disposed facing the surface of the first roller, each operation mode of a printing mode, a standby mode, and an energy saving mode is set, and the setting in each operation mode is performed. temperature,
A temperature control method for a fixing device, characterized by having a relationship of printing mode> standby mode> energy saving mode.

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