JP2000047521A - Fixing device and image forming apparatus provided with the fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device which quickly sets a target fixing- temperature for a recording medium with different fixing conditions so that the recording medium is fixed under the optimum fixing conditions and which prevents the recording medium from being wrapped around a fixing body, and an image forming device equipped with the fixing device. SOLUTION: For an OHP sheet which is different in fixing conditions from plain paper, a power control circuit and a temperature-adjustment control circuit switch a fixing roller 101 to an optimum target fixing-temperature and, according to a temperature detected by a thermister 203, adjust the supply of power to a heater H from a power source and also the drive of a fan 10 so that the fixing roller 101 maintains the target fixing-temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device and an image forming apparatus provided with the fixing device.

[0002]

2. Description of the Related Art Conventionally, in a fixing device, a separating means which comes into contact with the fixing roller so that a transfer sheet as a recording medium is not wound around a fixing roller as a fixing member after a fixing process is performed. A fixing device in which the separation claw is separated from the fixing roller by the provision of the separation claw so that the transfer paper subjected to the fixing process is separated from the fixing roller and discharged outside the fixing device is known, and is practically used. I have.

In such a fixing device, the surface of the fixing roller is usually coated with Teflon (registered trademark),
Oil is applied to the surface of the Teflon coating.

Accordingly, when the separating claw provided in such a fixing device is in contact with the fixing roller with an appropriate contact force, the fixing roller is damaged by the separating claw because the friction coefficient between the fixing roller and the separating claw is small. It is becoming less.

However, in such a fixing device, when an OHP (overhead projector) sheet (hereinafter, referred to as an OHP sheet) is fixed, the fixing device is liable to be wound more easily than a normal sheet. Stagnant).

In the fixing nail jam, since the base material of the OHP sheet is usually made of PET (polyethylene terephthalate), the rigidity of the OHP sheet decreases and the viscoelasticity increases due to heat during the fixing process. This occurs when the force of winding the OHP sheet around the fixing roller is greater than the force of the separation claw separating the OHP sheet.

Therefore, in such a conventional fixing device, in order to prevent the jam of the fixing claw, the amount of oil applied to the surface of the fixing roller is increased, and the force for peeling the OHP sheet is increased.

[0008]

However, when the amount of oil applied to the surface of the fixing roller is increased, not only does the oil adhere to the surface of the OHP sheet so that the user can recognize it, but also the fixing process is performed on normal paper. At this time, the oil is absorbed by the paper, and there is a possibility that the adverse effect of oil contamination may occur.

In a general color copying machine, as disclosed in Japanese Patent Application Laid-Open No. 7-295440, the fixing temperature and the temperature are adjusted so that an optimal fixing process is performed when an image is formed on plain paper. The fixing speed has been set. However, when fixing an image formed on an OHP sheet, the heat capacity of the OHP sheet needs to be higher than that of plain paper, and the fixing temperature needs to be higher or the fixing speed must be lower. In particular, when multiple transfer of toner images of different colors is performed on an OHP sheet as in a color copying machine, it is necessary to apply a sufficient amount of heat to mix the multiple toners. For this reason,
When an image is formed on an OHP sheet, the copy mode is changed from “plain paper mode” to “OHP mode” on the operation panel.
, The fixing conditions are switched so that the optimum fixing conditions can be obtained for each recording sheet.

[0010] Here, in many cases, a copy of the conference manuscript is required in addition to the OHP sheet from the conference manuscript for the number of participants. Consider the operation when such a material is created using a copying machine.

In this case, in the conventional copying machine, first, the first document is placed on the platen glass of the copying machine, and then the "OHP mode" is selected to increase the fixing temperature, thereby reducing the number of copies. After setting one sheet, press the copy start button. As a result, after the image of the first document is formed on the first OHP sheet, fixing is performed under conditions suitable for the OHP sheet, that is, at the time of color copying, at a temperature higher than that of plain paper, An image corresponding to the image of the first document is recorded on the first OHP sheet.

On the other hand, in black-and-white copying, fixing can be performed at a lower temperature than in the case of plain paper. This is because the black-and-white OHP sheet coats the base PET film with the PP resin to improve the fixability of the toner. Incidentally, since the PP resin is 70 to 80 ° C. lower than PET, it can be fixed at around 170 ° C. with a toner (resin) having low physical properties.

On the other hand, when a fixing process is performed on plain paper, the plain paper requires a fixing temperature of about 200 ° C. in order to melt and fix the toner between the paper fibers.

Japanese Patent Application Laid-Open No. 7-295440 discloses an OHP sheet and a plain paper for copying a plurality of OHP sheets and a plurality of plain papers corresponding to a plurality of originals, in order to reduce the waiting time and the overall copy time. Has been proposed for a copying procedure for continuously copying.

However, there is no disclosure of a method for quickly changing the fixing condition normally set in the "plain paper mode" to the "OHP mode" to shorten the waiting time.

Therefore, according to the present invention, a target fixing temperature is quickly set so that the recording medium is subjected to fixing processing under optimum fixing conditions for recording media having different fixing conditions, and the recording medium is wound around the fixing member. It is an object of the present invention to provide a fixing device that does not require the fixing and an image forming apparatus including the fixing device.

[0017]

According to the present invention, the object is to apply heat to a recording medium while pressing a fixing body and a pressing body through a recording medium carrying an unfixed image. A fixing unit for fixing the unfixed image to the recording medium by heating, a heating unit that generates heat by supplying power from a power supply, a rotatable fixing body that conducts heat from the heating unit, and the recording medium. A pressurizing member which rotates while being in pressure contact with the fixing member via the fixing member; a detecting means for detecting a temperature of the fixing member; And a control unit for adjusting the supply of electric power to the fixing device, the control unit having a cooling unit for cooling the fixing body, and the control unit can switch the respective target fixing temperatures for recording media having different fixing conditions. And the fixing body is So as to maintain the target fixing temperature is achieved by the fact that it is possible to adjust the driving of the cooling means.

Further, according to the present application, the above object is achieved in the first aspect in that, when the target fixing temperature of the fixing member is switched from a high temperature to a low temperature, the control means controls the power supply until the target fixing temperature is reached. From the power to the heating means,
The present invention is also achieved by the second invention in which the cooling means is driven from a power supply.

Further, according to the present application, the above object is achieved in the second aspect, wherein the fixing member and the pressure member are rotated until the target fixing temperature reaches the target fixing temperature when the target fixing temperature is switched from a high temperature to a low temperature. This is also achieved by the third invention which is possible.

Further, according to the present application, the object is to provide a rotatable fixing member, a pressurizing member which rotates while pressing against the fixing member via the recording medium, and a recording member which contacts the fixing member and records from the fixing member. A fixing member having a separating member for separating the medium, the converting device having a pressure changing means for applying and changing the contact pressure of the separating member to the fixing member; The present invention is also achieved by the fourth invention in which the contact pressure can be switched.

Further, according to the present application, the above-mentioned object is achieved by applying heat to the recording medium while pressing the fixing body and the pressing body through the recording medium carrying the unfixed image, thereby applying the heat to the recording medium. A fixing device for fixing an image on the recording medium, wherein a heating unit that generates heat by supplying power from a power supply,
A rotatable fixing body that conducts heat from a heating unit, a pressurizing body that rotates by pressing against the fixing body via the recording medium, a detecting unit that detects the temperature of the fixing body, and a detection temperature of the detecting unit. A fixing unit that adjusts the supply of power from the power supply to the heating unit so that the fixing body maintains the target fixing temperature, and a separation member that contacts the fixing body and separates the recording medium from the fixing body. The apparatus includes a cooling unit that cools the fixing member, and a transforming unit that applies pressure to the fixing member to apply pressure to the fixing member. The contact pressure can be switched, and the control means can switch respective target fixing temperatures for recording media having different fixing conditions,
The invention is also achieved by the fifth invention in which the driving of the cooling unit can be adjusted according to the switching of the target fixing temperature.

According to the present application, the above object is achieved in the fifth aspect of the present invention in that, when the target fixing temperature of the fixing member is switched from a high temperature to a low temperature, the control means controls the power supply until the target fixing temperature is reached. From the power to the heating means,
In addition, this is also achieved by the sixth invention in which the cooling means is driven from a power supply.

Further, according to the present application, the above object is achieved in the sixth aspect, wherein the fixing member and the pressure member are rotated until the target fixing temperature reaches the target fixing temperature when the target fixing temperature is switched from a high temperature to a low temperature. This is also achieved by the seventh invention which is possible.

According to the present application, an object of the present invention is to provide an image forming apparatus for recording an image formed by a series of image forming processes on a recording medium, the image forming apparatus including a first invention fixing device. It is also achieved by the invention.

Further, according to the present application, the above object is achieved according to the eighth invention in that, when the target fixing temperature of the fixing member is switched from a high temperature to a low temperature, the control means controls the power supply until the target fixing temperature is reached. The present invention is also achieved by shutting off the electric power from the power supply to the heating means and driving the cooling means from the power supply.

According to the present application, the above object is achieved in the ninth aspect in that the fixing member and the pressing member are rotated until the target fixing temperature reaches the target fixing temperature when the target fixing temperature is switched from a high temperature to a low temperature. This is also achieved by the tenth invention that is possible.

Further, according to the present application, the object is to provide an image forming apparatus for recording an image formed by a series of image forming processes on a recording medium, the tenth aspect including the fixing device of the fourth invention. This is also achieved by one invention.

Further, according to the present application, the object is to provide an image forming apparatus for recording an image formed by a series of image forming processes on a recording medium, which is provided with a fixing device according to the fifth invention. This is also achieved by the second invention.

Further, according to the present application, the above object is achieved in the twelfth aspect, wherein the control means reaches the target fixing temperature when the target fixing temperature of the fixing member is switched from a high temperature to a low temperature. This is also achieved by the thirteenth invention in which the power supply to the heating means is cut off from the power supply and the cooling means is driven from the power supply.

Further, according to the present application, the above object is achieved in the thirteenth aspect, in which the fixing member and the pressure member are connected until the target fixing temperature reaches the target fixing temperature when the target fixing temperature is switched from a high temperature to a low temperature. The invention is also achieved by a fourteenth invention that is rotatable.

That is, in the first invention according to the present application, the control means switches to the respective target fixing temperatures for the recording media having different fixing conditions, and performs the fixing in accordance with the detected temperature of the detecting means. The power supply from the power supply to the heating means is adjusted and the driving of the cooling means is adjusted so that the body is maintained at the target fixing temperature.

In the second invention according to the present application, when the control unit switches the target fixing temperature of the fixing member from a high temperature to a low temperature, the control unit controls the detection unit until the target temperature reaches the target temperature. In accordance with the detected temperature, the power supply from the power supply to the heating unit is cut off and the cooling unit is driven so that the fixing body maintains the target fixing temperature.

Further, according to the third aspect of the present invention, when the target fixing temperature of the fixing member is switched from a high temperature to a low temperature, the fixing member and the pressure member are kept until the target temperature is reached. Rotate, and the control unit controls the fixing body to maintain the target fixing temperature according to the detection temperature of the detection unit,
While cutting off the supply of power from the power supply to the heating means,
The cooling means is driven.

According to the fourth aspect of the present invention, the variable means switches the contact pressure of the separating means to the fixing member for recording media having different fixing conditions.

Further, in the fifth invention according to the present application, the variable means switches the contact pressure of the separating means to the fixing member for recording media having different fixing conditions, and the control means comprises:
Switching to the respective target fixing temperatures for the recording media having different fixing conditions, and supplying the power from the power supply to the heating means so that the fixing body maintains the target fixing temperature according to the temperature detected by the detecting means. The adjustment and the driving of the cooling means are adjusted.

According to the sixth aspect of the present invention, the variable means switches the contact pressure of the separating means to the fixing member with respect to the recording medium having different fixing conditions, thereby achieving the target fixing of the fixing member. When the temperature is switched from high to low,
Until the target temperature is reached, the control means cuts off the supply of power from the power supply to the heating means so as to maintain the fixing body at the target fixing temperature in accordance with the detected temperature of the detection means, and controls the cooling means. Drive.

In the seventh invention according to the present application, the variable means switches the contact pressure of the separation means to the fixing member for the recording medium having different fixing conditions, thereby changing the target fixing of the fixing member. When the temperature is switched from high to low,
The fixing body and the pressure body rotate until the target temperature is reached, and the control means controls the power from the power supply to the heating means so that the fixing body is maintained at the target fixing temperature in accordance with the temperature detected by the detection means. And the cooling means is driven.

Further, in the eighth invention according to the present application, the control means switches to the respective target fixing temperatures for the recording media having different fixing conditions, and performs the fixing in accordance with the detected temperature of the detecting means. The power supply from the power supply to the heating means is adjusted and the driving of the cooling means is adjusted so that the body is maintained at the target fixing temperature.

According to the ninth aspect of the present invention, when the control unit switches the target fixing temperature of the fixing member from a high temperature to a low temperature, the control unit controls the detection unit until the target fixing temperature is reached. In accordance with the detected temperature, the power supply from the power supply to the heating unit is cut off and the cooling unit is driven so that the fixing body maintains the target fixing temperature.

Further, according to the tenth aspect of the present invention, when the target fixing temperature of the fixing member is switched from a high temperature to a low temperature, the fixing member and the pressure member are kept until the target temperature is reached. Rotate, and the control unit controls the fixing body to maintain the target fixing temperature according to the detection temperature of the detection unit,
While cutting off the supply of power from the power supply to the heating means,
The cooling means is driven.

In the eleventh invention according to the present application, the variable means switches the contact pressure of the separating means to the fixing member for recording media having different fixing conditions.

Further, in the twelfth invention according to the present application, the variable means switches the contact pressure of the separating means to the fixing member for recording media having different fixing conditions, and the control means comprises: Switching to the respective target fixing temperatures for the recording media having different fixing conditions, and according to the detected temperature of the detecting means,
The supply of power from the power supply to the heating unit is adjusted and the driving of the cooling unit is adjusted so that the fixing body is maintained at the target fixing temperature.

According to the thirteenth aspect of the present invention, the variable means switches the contact pressure of the separating means to the fixing member with respect to the recording medium having different fixing conditions, and sets the target of the fixing member. When the fixing temperature is switched from high to low,
Until the target temperature is reached, the control means cuts off the supply of power from the power supply to the heating means so as to maintain the fixing body at the target fixing temperature in accordance with the detected temperature of the detection means, and controls the cooling means. Drive.

Further, in the fourteenth invention according to the present application, the variable means switches the contact pressure of the separating means to the fixing member for recording media having different fixing conditions, and sets the target of the fixing member. When the fixing temperature is switched from a high temperature to a low temperature, the fixing body and the pressure body rotate until the target temperature is reached, and the control unit causes the fixing body to move to the target fixing state according to the detection temperature of the detection unit. In order to maintain the temperature, the supply of power from the power supply to the heating means is cut off, and the cooling means is driven.

[0045]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

(First Embodiment) First, an electrophotographic copying machine 100 (hereinafter, referred to as a copying machine 100) as an example of an image forming apparatus according to a first embodiment of the present invention will be described with reference to FIGS. explain.

As shown in FIG. 1, the copying machine 100 includes a drum-shaped rotatable photosensitive member 2 serving as a latent image carrier, a developing device 5, and an exposure process corresponding to image information from a document. A laser scanner unit 4 (hereinafter, abbreviated as a scanner 4) for forming an electrostatic latent image corresponding to the image information on the outer peripheral surface of the recording medium 2, and a transfer processing step for a transfer material P as a recording medium. A roll-shaped rotatable transfer body 6,
And a fixing device 1 for applying a fixing process to the transferred transfer material P by applying heat and pressure.

Around the photosensitive member 2 provided in the copying machine 100, a rotatable primary charging roller 3 for charging the outer peripheral surface of the photosensitive member 2 to a prescribed potential distribution before exposure processing by the scanner 4 is provided. The primary charging roller 3 is configured to be charged to a specified potential distribution from a commercial power supply or the like before exposure processing by the scanner 4.

The scanner 4 provided in the copying machine 100
By scanning and exposing a charged portion of the outer peripheral surface of the photoconductor 2 with a laser La corresponding to a time-series electric digital pixel signal of image information from a document, an electrostatic latent image corresponding to the image information is formed. It is formed on the outer peripheral surface.

Next, a series of image forming processes in the copying machine 100 will be described.

First, when a start button or the like (not shown) provided on the main body of the copying machine 100 is pressed to instruct the copying machine 100 to start a series of image forming processes, the photosensitive member 2 is moved by an arrow K1. In this direction, the rotating drive is started at a specified peripheral speed, and the outer peripheral surface of the photoconductor 2 is charged to a specified potential distribution by the charging roller 3 and the photosensitive member 2 to which a specified bias is applied, slidingly contacting each other. Can be

Next, the charged portion of the outer peripheral surface of the photoreceptor 2 is scanned and exposed by the scanner 4 according to the image information from the image information providing device, so that the electrostatic latent image corresponding to the image information is obtained. Is formed in the above-described portion, the electrostatic latent image is visualized into a visible image by the developer of the developing device 5, and a predetermined number of transfer materials P can be stored and the main body of the copying machine 100 Cassette 8 detachably supported
The visible image is transferred by the transfer member 6 onto the transfer material P which is conveyed at a predetermined timing or the like to a space formed between the photosensitive member 2 and the transfer member 6 by a paper feed roller 8a or the like that is rotatable. Is done.

Then, the transfer material P after transfer processing (hereinafter, referred to as transfer material P)
The transfer material P carrying the unfixed image is subjected to a fixing process by the fixing device 1 and then discharged outside the apparatus by a discharge roller 20a rotatably supported by the main body of the copying machine 100. By stacking on the tray 20 attached to one side surface of the main body, a series of image forming processes is completed.

Next, the fixing device 1 provided in the copying machine 100 according to the present embodiment will be described with reference to FIG.

FIG. 2 is a schematic sectional view showing a schematic configuration of the fixing device 1 provided in the copying machine 100 of FIG.

As shown in FIG. 2, the fixing device 1 includes a fixing roller 101 as a fixing member, a heater H as a heating unit, a pressure roller 102 as a pressing unit, a thermistor 203 as a detecting unit, and a cooling unit. The copying machine 100 includes a fan 10 and a separating claw 103 serving as a separating unit. The control unit 7 includes a power control circuit and a temperature control circuit (both not shown) serving as control units inside the copying machine 100.

The fixing roller 101 has a heater H for supplying electric power from a power supply such as a commercial power supply and generating heat. The heater H is covered with a non-adhesive resin or rubber on a core metal such as aluminum. Is rotated in the direction indicated by.

A thermistor 203 is disposed in contact with the outer peripheral surface of the fixing roller 101, and sends a detection signal to a temperature control circuit to maintain the temperature of the outer peripheral surface of the fixing roller 101 at a toner melting temperature which is a target fixing temperature. It has become.

The pressure roller 102 has a coating of a relatively thick layer of an elastic material such as silicone rubber on its surface, and presses the fixing roller 101 to transfer the transfer material P carrying the unfixed image T. Has become.

An entrance guide 13 is provided in front of the fixing roller 101 and the pressure roller 102, and a transfer material P on which a toner image T is formed by a known electrophotographic process.
Along the upper surface of the entrance guide 13 to the nip of the fixing roller 101 and the pressure roller 102.

As a result, the unfixed image on the transfer material P passing through the nip is fixed to the fixing roller 101 and the pressure roller 10.
2 and is fixed on the transfer material P by heating and pressing.

A transfer path 14 is provided ahead of the nip in the transfer direction of the transfer material P, and the transfer material P is discharged onto an external tray 20.

Further, in order to remove the offset toner on the surface of the fixing roller 101, the web cleaning device 20 is used.
5 are arranged around the fixing roller 101.

The web cleaning device 205 includes a cleaning web 206 that moves while being pressed against the surface of the fixing roller 101, a supply roller 207 that supplies the web 206, and a winding roller 2 that winds the web 206.
08 and the cleaning web 206 are fixed to the fixing roller 101.
And a pressing roller 209 that presses against the surface.

The separation claw 103 separates the transfer material P, which is attached to the surface of the fixing roller 101 and is to be wound around the fixing roller 101, from the fixing roller 101.

In the present invention, the separating claw 103 is formed by coating a polyimide or polybenzimidazole with a fluororesin such as PFA. By using such a heat-resistant and abrasion-resistant resin as the base material of the separation claw, it is possible to complete the sintering of the coated fluororesin, and it is possible to reduce the toxicity of the fluororesin to the base material. Improvements and wear resistance have been made. In addition, since the lower separation claw 210 is in contact with the pressure row 102 at a lower temperature than the fixing roller 101, a low-cost, low-cost PPS or polyamide resin is used.

FIGS. 2 and 3 show an embodiment of the present invention in which a drive system for reciprocating (hereinafter, referred to as reciprocating) of the separation claw 3 is taken from the shaft of the paper discharge roller 20a. 4 shows a configuration around the roller 101, FIG. 4 shows a reciprocating mechanism, and FIG. 5 shows an arrangement of a drive system.

The separation claw 103 is rotatable about a rotation shaft 104 with respect to a holder 105 fixed to a mounting plate 106, and is urged by a tension spring 120 to apply a predetermined pressure in the direction A in FIG. It is in contact with the fixing roller 101.

The mounting plate 106 is rotatable about a rotation shaft 108, and is extended by a tension spring 109 as shown in FIG.
Is applied to the fixing roller 101 and is positioned at a predetermined position of the fixing roller 101. The position in the reciprocating direction is given a biasing force in the direction C in FIG. 4 by a tension spring 110, and the reciprocating shaft 111 fixed to the mounting plate 106 abuts against the reciprocating cam gear 113 and is fixed. Further, a reciprocating shaft 116 fixed to a reciprocating base 115 to which the reciprocating cam gear 113 and the motor 114 are fixed abuts on the reciprocating cam gear 117 and is positioned. The shape of each of the reciprocating cam gears 113 and 117 is obtained by diagonally cutting a cylinder and is shown in FIG.

First, referring to FIG.
Rotates very little by little with the rotation of the fixing roller 101 to rotate the reciprocating cam gear 113. Then, the reciprocating shaft 111 moves on the slope of the cam portion, and causes the mounting plate 106 to reciprocate in the axial direction of the fixing roller 101. FIG. 5 (A)
Indicates that the reciprocating shaft 116 is in contact with the apex of the cam portion of the reciprocating cam gear 117, that is, the mounting plate 106
Is located at the farthest side.

When the fixing roller 101 is stopped, an indentation is formed in the contact area between the fixing roller 101 and the separation claw 3, so that the rotation of the copying machine 100 when the copy is turned on or the main switch is turned on. Later, or when the fixing roller 101 starts to rotate from a stopped state as in a pre-rotation after the paper jam processing, the separation claw 103 may bite into the fixing roller 101. Therefore, in this embodiment, before the fixing roller 101 is rotated, the motor 118 is driven to rotate the reciprocating cam gear 117 by 180 ° so that the reciprocating shaft 116 abuts the most valley portion of the reciprocating cam gear 117 as shown in FIG. Rotate. In the present invention, this is the height difference between the cams of the reciprocating cam gear 117 and the amount of movement y by the separation claw 103.
Is set to be larger than the claw width x of the separation claw 103, so that the indented portion formed by the separation claw 103 and the separation claw 103 are separated.
Thereafter, even when the fixing roller 101 is rotated, the separation claw 3 does not bite into the fixing roller. Further, when the rotation of the fixing roller 101 is once stopped and then rotated again, similarly to the above-described operation, the state shown in FIG.
Since it is rotated after being moved to the state (A), it does not bite into the fixing roller 101. After that Figure 5
The transition between the state shown in FIG. 5A and the state shown in FIG. 5B is repeated after stopping the rotation of the fixing roller 101 and before rotating the fixing roller 101 again, thereby preventing biting into the fixing roller 101. I have.

In this embodiment, the motor 118
The reciprocating cam base 115 is moved via the reciprocating cam gear 117 by using the rotation of the reciprocating cam, but may be moved by a mechanical, physical or electric mechanism such as a solenoid.

FIG. 9 is a schematic top view of the fixing device 1 according to the present embodiment.

In the vicinity of the fixing roller 101, a cooling fan 10 for rapidly cooling the fixing roller 101 is provided in communication with the duct 11.

In the OHP mode, the cooling fan 10 is operated to rotate the fixing roller 101, thereby promoting the cooling of the surface of the fixing roller 101.

When the surface temperature of the fixing roller 101 reaches 170 ° C., the OHP sheet is fixed. When the user does not select the OHP mode, that is, when the fixing process is performed on plain paper, Fixing roller 101
Is fixed at 200 ° C. in the standby state, and plain paper is fixed.

FIG. 7 shows a fixing roller 1 according to this embodiment.
FIG. 8 is a block diagram schematically illustrating the temperature control of the fixing roller 101, and FIG. 8 is a flowchart illustrating the temperature control of the fixing roller 101.

As shown in FIG. 7, when the power of the copying machine 100 is turned on, the power is supplied to the heater H from the power supply, and the temperature on the surface of the fixing roller 101 rises. Then, the thermistor 203 is
The temperature on the surface is detected.

As shown in FIG. 8, the power of the copying machine 100 is turned on in the copying machine 100 (S10).
1) The power control circuit and the temperature control circuit adjust the power to the heater H, and control the fixing roller 101 to reach 200 ° C., which is the optimum temperature of plain paper (S102).

When the temperature of the fixing roller 102 reaches 200 ° C., the wait-up is completed (S103), and the apparatus enters a standby state (S104).

The user inputs the copy mode (S10
5) When the start key is pressed (S106), the target fixing temperature is set and controlled so that the surface temperature of the fixing roller 101 is different depending on whether the copy mode is OHP or not (S107).

That is, when the OHP mode is selected,
The OHP compatible fan 11 near the fixing device 1 is operated (S
108), the target fixing temperature on the surface of the fixing roller 102 is set to 170 ° C., which is 30 ° C. lower than in the plain paper mode, and control is performed (S109).

On the other hand, when the OHP mode is not selected (in the case of plain paper), control is performed by setting the target fixing temperature on the surface of the fixing roller 101 to 200 ° C. in the plain paper mode (S11).
1).

Thus, according to the present embodiment, the power control circuit and the temperature adjustment control circuit use different OHs having different fixing conditions from those of plain paper.
The power is switched from the power supply to the heater H so that the fixing roller 101 is maintained at the target fixing temperature according to the temperature detected by the thermistor 203 by switching to the optimum target fixing temperature for the P sheet.
The fixing roller 101 can quickly reach the optimum target fixing temperature for the OHP sheet because the power supply to the OHP sheet is adjusted and the driving of the fan 10 is adjusted. Can be prevented from being wound around.

Further, according to the present embodiment, when the power control circuit and the temperature adjustment control circuit switch the target fixing temperature of the fixing roller 101 from a high temperature to a low temperature (the fixing condition is changed from plain paper to OHP sheet). Until the target temperature is reached, the supply of electric power from the power supply to the heater H is cut off and the fan is stopped so that the fixing roller 101 maintains the target fixing temperature in accordance with the temperature detected by the thermistor 203. Since the setting is made so that the OHP sheet 10 is driven, the fixing roller 101 can quickly reach the optimum target fixing temperature for the OHP sheet, and the OHP sheet can be prevented from winding around the fixing roller 101.

Further, according to the present embodiment, the fixing roller 1
When the target fixing temperature No. 01 is switched from a high temperature to a low temperature (when the fixing condition is switched from plain paper to an OHP sheet), the fixing roller 101 and the pressure roller 102 rotate until the target temperature is reached. The power control circuit and the temperature adjustment control circuit cut off the supply of electric power from the power supply to the heater H so as to maintain the fixing roller 101 at the target fixing temperature in accordance with the temperature detected by the thermistor 203. , The fixing roller 101 can quickly reach the optimum target fixing temperature for each of the OHP sheets having different fixing conditions, thereby preventing the OHP sheet from winding around the fixing roller 101.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. In addition, about the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

In the fixing device of the present embodiment, FIG.
As shown in FIG. 11, the fixing roller 1 of the separation claw 103
It has a solenoid SL as a variable means for making the contact force against 01 a variable pressure.

FIG. 12 shows the fixing claw 103 and the solenoid SL.
3 is a flowchart for explaining the control of FIG.

In this embodiment, as shown in FIG. 12, when the image forming apparatus main body is turned on (S20).
1) The power control circuit and the temperature control circuit as control means adjust the power to the heater H to control the surface temperature of the fixing roller 101 to 200 ° C. (S202).

The user inputs a copy mode (S20).
5) When the start key is pressed (S206), control is performed such that the contact pressure of the fixing claw 103, which is a separating unit, with the fixing roller 101 differs depending on whether the copy mode is the OHP mode or not (S207).

When the OHP mode is not selected, as shown in FIG. 11, the solenoid SL is in the OFF state (S210), the contact pressure of the fixing claw 103 at this time is about 20 gr, and the plain paper is Is completely separated from the fixing roller 101 so that the fixing roller 101 is not damaged.

On the other hand, when the OHP mode is selected, FIG.
As shown in FIG. 0, the solenoid SL is in the ON state (S208), the contact pressure of the fixing claw 103 at this time is about 60 gr, and in this embodiment, the rigidity of the OHP sheet is increased by the fixing heat. Fixing roller 1 with lower viscoelasticity
Even when the OHP sheet is wound around the fixing roller 101, the OHP sheet can be reliably separated from the fixing roller 101.

In order to prevent the fixing claw 103 from damaging the fixing claw 103, the solenoid SL is normally turned off except that an OHP sheet is used so that the contact pressure of the fixing claw 103 is about 20 gr. Set to.

Therefore, according to the present embodiment, the solenoid SL switches the contact pressure of the separation claw 103 to the fixing roller 101 for the OHP sheet having the fixing condition different from that of the plain paper, and the power control circuit and the temperature adjustment. The control circuit switches to the target fixing temperature corresponding to the OHP sheet, and thermistor 2
Since the supply of power from the power supply to the heater H is adjusted and the driving of the fan 10 is adjusted so that the fixing roller 101 maintains the target fixing temperature in accordance with the detected temperature of 03, the setting is made. Fixing roller 1 of separation claw 103
01 is set optimally, the OHP sheet is reliably separated from the fixing roller 101, and the fixing roller 101 can quickly reach the optimum target fixing temperature for the OHP sheet. 1
01 can be prevented.

[0096]

As described above, according to the first aspect of the present invention, the control means switches to the respective target fixing temperatures for the recording media having different fixing conditions, and the control means controls the detection means. In accordance with the detected temperature, the supply of power from the power supply to the heating unit is adjusted so that the fixing body is maintained at the target fixing temperature, and the driving of the cooling unit is set. Optimal target fixing temperatures can be quickly reached for recording media having different fixing conditions, respectively, and the recording medium can be prevented from winding around the fixing member.

According to the second invention of the present application,
When the control unit switches the target fixing temperature of the fixing body from a high temperature to a low temperature, until the target temperature is reached,
Since the supply of power from the power supply to the heating unit is cut off and the cooling unit is driven so that the fixing body maintains the target fixing temperature in accordance with the detection temperature of the detection unit, the fixing unit is set. The body can quickly reach the optimum target fixing temperature for each of the recording media having different fixing conditions, and the recording medium can be prevented from winding around the fixing body.

Further, according to the third aspect of the present invention, when the target fixing temperature of the fixing member is switched from a high temperature to a low temperature, the fixing member and the pressure member rotate until the target temperature is reached. The control unit controls the fixing unit to maintain the target fixing temperature according to the temperature detected by the detection unit.
While cutting off the supply of power from the power supply to the heating means,
Since the cooling means is set to be driven, the fixing body can quickly reach the optimum target fixing temperature for each of the recording media having different fixing conditions, and the recording medium can be prevented from winding around the fixing body.

According to the fourth invention of the present application,
Since the variable unit is set to switch the contact pressure of the separation unit to the fixing body with respect to the recording medium having different fixing conditions, the contact pressure of the separation unit to the fixing body with respect to the recording medium having different fixing conditions is changed. The recording medium is set optimally, and the recording medium can be reliably separated from the fixing body, and the recording medium can be prevented from winding around the fixing body.

Further, according to the fifth aspect of the present invention, the variable means switches the contact pressure of the separation means to the fixing member for recording media having different fixing conditions, and the control means comprises:
Switching to the respective target fixing temperatures for the recording media having different fixing conditions, and supplying the power from the power supply to the heating means so that the fixing body maintains the target fixing temperature according to the temperature detected by the detecting means. In addition to the adjustment, the driving of the cooling unit is set to be adjusted. Therefore, the contact pressure of the separation unit to the fixing body is set optimally for the recording medium having different fixing conditions, and the recording medium is reliably removed from the fixing body. In addition to the separation, the fixing body can quickly reach the optimum target fixing temperature for each of the recording media having different fixing conditions, thereby preventing the recording medium from being wound around the fixing body.

According to the sixth invention of the present application,
The variable unit switches the contact pressure of the separation unit to the fixing body for recording media having different fixing conditions, and reaches the target temperature when the target fixing temperature of the fixing unit is switched from a high temperature to a low temperature. Up to this point, the control unit is set to cut off the supply of power from the power supply to the heating unit and to drive the cooling unit so that the fixing body is maintained at the target fixing temperature according to the temperature detected by the detection unit. Therefore, the contact pressure of the separating unit with the fixing member for the recording medium having different fixing conditions is optimally set, and the recording medium can be reliably separated from the fixing member. It is possible to quickly reach the optimum target fixing temperature for each recording medium, and to prevent the recording medium from winding around the fixing member.

Further, according to the seventh invention of the present application,
The variable unit switches the contact pressure of the separation unit to the fixing body for recording media having different fixing conditions, and reaches the target temperature when the target fixing temperature of the fixing unit is switched from a high temperature to a low temperature. Until the fixing member and the pressure member rotate, and the control unit cuts off the supply of power from the power supply to the heating unit so that the fixing unit maintains the target fixing temperature according to the temperature detected by the detection unit. At the same time, since the cooling unit is set to be driven, the contact pressure of the separating unit to the fixing body is set optimally for the recording medium having different fixing conditions, so that the recording medium can be surely separated from the fixing body. And the fixing body can quickly reach the optimum target fixing temperature for recording media having different fixing conditions, respectively.
It is possible to prevent the recording medium from being wound around the fixing member.

Further, according to the eighth aspect of the present invention, the control means switches to the respective target fixing temperatures for the recording media having different fixing conditions, and according to the detected temperature of the detecting means, the fixing means. Is set so as to adjust the supply of power from the power supply to the heating means and to adjust the driving of the cooling means so as to maintain the target fixing temperature. The respective optimum target fixing temperatures can be quickly reached, and the recording medium can be prevented from winding around the fixing member.

Further, according to the ninth invention of the present application,
When the control unit switches the target fixing temperature of the fixing body from a high temperature to a low temperature, until the target temperature is reached,
Since the supply of power from the power supply to the heating unit is cut off and the cooling unit is driven so that the fixing body maintains the target fixing temperature in accordance with the detection temperature of the detection unit, the fixing unit is set. The body can quickly reach the optimum target fixing temperature for each of the recording media having different fixing conditions, and the recording medium can be prevented from winding around the fixing body.

Further, according to the tenth aspect of the present invention, when the target fixing temperature of the fixing member is switched from a high temperature to a low temperature, the fixing member and the pressure member rotate until the target temperature is reached. The control unit controls the fixing unit to maintain the target fixing temperature according to the temperature detected by the detection unit.
While cutting off the supply of power from the power supply to the heating means,
Since the cooling means is set to be driven, the fixing body can quickly reach the optimum target fixing temperature for each of the recording media having different fixing conditions, and the recording medium can be prevented from winding around the fixing body.

Further, according to the eleventh aspect of the present invention, since the variable means is set so as to switch the contact pressure of the separation means to the fixing member for recording media having different fixing conditions, The contact pressure of the separating unit to the fixing member is optimally set for recording media having different conditions, and the recording medium can be reliably separated from the fixing member, and the recording medium can be prevented from winding around the fixing member. .

Further, according to the twelfth invention of the present application, the variable means switches the contact pressure of the separation means to the fixing member for recording media having different fixing conditions, and the control means comprises:
Switching to the respective target fixing temperatures for the recording media having different fixing conditions, and supplying the power from the power supply to the heating means so that the fixing body maintains the target fixing temperature according to the temperature detected by the detecting means. In addition to the adjustment, the driving of the cooling unit is set to be adjusted. Therefore, the contact pressure of the separation unit to the fixing body is set optimally for the recording medium having different fixing conditions, and the recording medium is reliably removed from the fixing body. In addition to the separation, the fixing body can quickly reach the optimum target fixing temperature for each of the recording media having different fixing conditions, thereby preventing the recording medium from being wound around the fixing body.

Further, according to the thirteenth aspect of the present invention, the variable means switches the contact pressure of the separating means to the fixing member for the recording medium having different fixing conditions, thereby achieving the target fixing of the fixing member. When the temperature is switched from high to low,
Until the target temperature is reached, the control means cuts off the supply of power from the power supply to the heating means so as to maintain the fixing body at the target fixing temperature in accordance with the detected temperature of the detection means, and controls the cooling means. Since it is set to be driven, the contact pressure of the separating unit with the fixing member for the recording medium having different fixing conditions can be set optimally, and the recording medium can be reliably separated from the fixing member. Can quickly reach the optimum target fixing temperatures for recording media having different fixing conditions, respectively, and can prevent the recording medium from winding around the fixing body.

Further, according to the fourteenth aspect of the present invention, the variable means switches the contact pressure of the separating means to the fixing member for the recording medium having different fixing conditions, thereby achieving the target fixing of the fixing member. When the temperature is switched from high to low,
The fixing body and the pressure body rotate until the target temperature is reached, and the control means controls the power from the power supply to the heating means so that the fixing body is maintained at the target fixing temperature in accordance with the temperature detected by the detection means. And the cooling unit is driven so that the contact pressure of the separating unit to the fixing member is optimally set for the recording medium having different fixing conditions, so that the recording medium is reliably transferred from the fixing member. Can be separated, and the fixing body can quickly reach the optimum target fixing temperature for each of the recording media having different fixing conditions, thereby preventing the recording medium from winding around the fixing body.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view illustrating a schematic configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view illustrating a schematic configuration of a fixing device provided in the image forming apparatus of FIG. 1 when fixing normal paper.

FIG. 3 is a schematic sectional view showing a schematic configuration of the fixing device of FIG. 2 at the time of fixing an OHP sheet.

FIG. 4 is a schematic top view illustrating a schematic configuration of a separating unit provided in the fixing device of FIG. 2;

5A is a schematic diagram illustrating a state in which the separation unit in FIG. 4 is in pressure contact with a fixing member, and FIG. 5B is a schematic diagram illustrating a state in which the separation unit is apart from the fixing member.

FIG. 6 is a perspective view showing a shape of a cam provided in the separating means of FIG.

FIG. 7 is a block diagram illustrating temperature control of a fixing member according to the first embodiment of the present invention.

FIG. 8 is a flowchart illustrating temperature control of a fixing member according to the first embodiment of the present invention.

FIG. 9 is a top view showing a schematic configuration of a cooling unit provided in the fixing device of FIG. 2;

FIG. 10 is a schematic cross-sectional view illustrating a schematic configuration of a fixing device according to a second embodiment of the present invention when an OHP sheet is fixed.

FIG. 11 is a schematic cross-sectional view showing a schematic configuration of the fixing device of FIG. 3 when fixing plain paper.

FIG. 12 is a flowchart illustrating control of a contact force of a separating unit to a fixing member according to a second embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fixing device 10 fan (cooling means) 100 copying machine (image forming apparatus) 101 fixing roller (fixing body) 102 pressure roller (pressing body) 103 separation claw (separating means) 203 thermistor (detecting means) SL solenoid (variable) Means) P transfer material (recording medium) H heater (heating means)

Claims (14)

[Claims] A fixing device for fixing the unfixed image to the recording medium by applying heat to the recording medium while pressing the fixing body and the pressing body through the recording medium carrying the unfixed image; A heating unit that generates heat by the supply of power from a power supply, a rotatable fixing body that conducts heat from the heating unit, and a pressurizing body that rotates by pressing against the fixing body via the recording medium. A fixing unit that detects a temperature of the fixing body, and a control unit that adjusts power supply from a power supply to a heating unit in accordance with the detected temperature of the fixing unit so as to maintain the fixing body at a target fixing temperature. In the apparatus, a cooling unit for cooling the fixing body is provided, and the control unit can switch the respective target fixing temperatures for recording media having different fixing conditions so that the fixing body is maintained at the target fixing temperature. Drive of cooling means The fixing device is adjustable. 2. The control device according to claim 1, wherein when the target fixing temperature of the fixing member is switched from a high temperature to a low temperature, the control unit cuts off power from the power supply to the heating unit until the target fixing temperature is reached.
The fixing device according to claim 1, wherein the cooling unit is driven from a power supply. 3. The fixing device according to claim 2, wherein the fixing body and the pressure body are rotatable until the target fixing temperature reaches the target fixing temperature when the target fixing temperature is switched from a high temperature to a low temperature. 4. A fixing device comprising: a rotatable fixing member; a pressurizing member that rotates while being pressed against the fixing member via the recording medium; and a separation member that contacts the fixing member and separates the recording medium from the fixing member. The apparatus has a pressure changing means for applying and changing the contact pressure of the separation member to the fixing member, and the pressure changing means can switch the contact pressure of the separation member for recording media having different fixing conditions. A fixing device characterized by the above-mentioned. 5. A fixing device for fixing the unfixed image to the recording medium by applying heat to the recording medium while pressing the fixing body and the pressing body through the recording medium carrying the unfixed image. A heating unit that generates heat by the supply of power from a power supply, a rotatable fixing body that conducts heat from the heating unit, and a pressurizing body that rotates by pressing against the fixing body via the recording medium. Detecting means for detecting the temperature of the fixing member, control means for adjusting power supply from a power supply to the heating means so as to maintain the fixing member at a target fixing temperature in accordance with the temperature detected by the detecting means, A fixing member that separates the recording medium from the fixing member by contacting the fixing member with the fixing member, comprising: a cooling unit that cools the fixing member; The transformer is a recording medium with different fixing conditions. The contact pressure of the separation member can be switched with respect to each of the members, and the control means can switch the respective target fixing temperatures for the recording media having different fixing conditions, and can respond to the switching of the target fixing temperature. Wherein the driving of the cooling means is adjustable. 6. When the target fixing temperature of the fixing member is switched from a high temperature to a low temperature, the control unit cuts off power from a power supply to the heating unit until the target fixing temperature is reached.
6. The fixing device according to claim 5, wherein the cooling unit is driven from a power supply. 7. The fixing device according to claim 6, wherein when the target fixing temperature is switched from a high temperature to a low temperature, the fixing member and the pressure member are rotatable until reaching the target fixing temperature. 8. An image forming apparatus for recording an image formed by a series of image forming processes on a recording medium,
An image forming apparatus comprising the fixing device according to claim 1. 9. When the target fixing temperature of the fixing member is switched from a high temperature to a low temperature, the control unit cuts off power from a power supply to the heating unit until the target fixing temperature is reached,
The image forming apparatus according to claim 8, wherein the cooling unit is driven from a power supply. 10. The image forming apparatus according to claim 9, wherein when the target fixing temperature is switched from a high temperature to a low temperature, the fixing member and the pressure member can rotate until the target fixing temperature is reached. 11. An image forming apparatus for recording an image formed by a series of image forming processes on a recording medium, wherein the image forming apparatus includes the fixing device according to claim 4. 12. An image forming apparatus for recording an image formed by a series of image forming processes on a recording medium, comprising the fixing device according to claim 5. 13. The control means, when the target fixing temperature of the fixing member is switched from a high temperature to a low temperature, shuts off power from a power supply to the heating means until the target fixing temperature is reached, The image forming apparatus according to claim 12, wherein the image forming apparatus is driven. 14. The image forming apparatus according to claim 13, wherein when the target fixing temperature is switched from a high temperature to a low temperature, the fixing member and the pressure member can rotate until reaching the target fixing temperature.