JPH07129012A - Heat fixing device - Google Patents

Abstract

(57) [Summary] [Object] To provide a thermal fixing device capable of removing residual toner on a heating roller without wasting electric power. [Structure] The solenoid 87 is turned on to press the cleaning pad 81 against the heating roller 30 (step 12).
At the same time, the heating roller 30 is rotated once to rotate the heating roller 3
The residual toner is removed over the entire circumference of 0 (step 1
3, determination step 14 is Yes). Then, the solenoid 87 is turned off to attach the cleaning pad 81 to the heating roller 3
0 (step 15), the cleaning pad 81 is pressure-bonded to the heating roller 30 so that the electrode layer 33 and the resistance layer 35 of the heating roller 30 do not come into contact with each other and the electric power is not wasted. Power is supplied to 30 (step 16), and fixing of the sheet is started.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal fixing device for thermally fixing toner used in electrophotographic printers, copying machines and the like onto paper.

[0002]

2. Description of the Related Art Conventionally, a heat roller using a halogen heater has been mainly used in a heat fixing device for fixing toner onto a sheet. The heat roller is composed of a hollow cylindrical roller made of a material having good heat conductivity such as aluminum or stainless steel. The heat roller is configured to rotate along the outer circumference of the halogen heater fixed in the hollow portion. Thus, the heat and adhesion required for fixing the paper and the toner are obtained. In addition, a pressure roller composed of heat-resistant silicone rubber is used, and the nip area necessary to obtain an appropriate pressure contact force and adhesiveness is sandwiched between the heat roller and the paper on which the toner image is transferred. To form.

Further, in such a heat fixing device,
A temperature sensor is provided in contact with the heat roller,
By adjusting the electric power applied to the halogen heater according to the detection result, the amount of heat supplied from the halogen heater is controlled to keep the surface temperature of the heat roller constant. In addition, a thermal fuse is provided near the heat roller to prevent fires by shutting off the power applied to the halogen heater when it becomes difficult to control the amount of heat emitted from the halogen heater due to some trouble in the heat fixing device. It is supposed to do. Further, in this type of heat fixing device, a cleaning device is provided in order to remove the residual toner slightly adhering to the surface of the heat roller during fixing. In this cleaning device, a cleaning pad made of felt or the like impregnated with silicon oil is pressed against the surface of the heat roller to remove the toner residue attached to the heat roller.

[0004]

However, in the thermal fixing device having such a configuration, the heating roller portion and the heating roller portion other than the portion in contact with the paper or the toner are heated by the halogen heater at the time of fixing and before and after fixing. The bearings, and even the air around the halogen heater are heated and exposed to high temperature. Therefore, there are various problems as described below. First, there is a problem in that members such as the heat roller, the pressure roller, the temperature sensor, and the bearing that supports the temperature fuse must be made of resin or metal having high heat resistance. In particular, there has been a problem that high heat resistance is required for bearings and the like of the rotating part of the heat roller. In addition, since the above-mentioned heating keeps almost the entire heat fixing device at a high temperature,
When a paper jam occurs during fixing, if the user tries to remove the paper near the heat fixing device or the user accidentally touches the heat fixing device, thermal protection is provided to prevent injury such as burns. It was necessary to completely cover the outer periphery of the heat fixing device with the cover made of a member. Otherwise, the heat fixing device must be installed in a place that cannot be touched by the user's hand, which has a drawback that the structure of the heat fixing device becomes complicated and the device itself becomes large. .

Secondly, in order to prevent each constituent member located on the outer periphery of the thermal fixing device from being affected by heat from the same thermal fixing device, each constituent member is installed separately from the thermal fixing device. Alternatively, it is necessary to provide a heat insulating member, an exhaust fan, or the like with another device (photoreceptor, developing device, scanner, toner, etc.). Therefore, there is a drawback that the structure of the printer or the copying machine becomes complicated and the size becomes large. Third, after the power is turned on from the initial state and before the surface temperature of the heat roller reaches the actual fixing temperature, the heat of the halogen heater is transmitted to the inner circumferential surface of the heat roller after the halogen heater is turned on. It was necessary to raise the temperature. For this reason, a certain amount of rising time is required between turning on the power and starting the fixing, which is inconvenient for the user. Fourth, as described above, the heat generated from the heat roller as a whole includes unnecessary heat generated for purposes other than the original purpose. Therefore, there is a disadvantage in that the power consumed is very large.

Fifth, in order to shorten the rise time of the heat fixing device as much as possible, it is necessary to keep the temperature of the heat roller at a certain temperature during the time after the power is turned on and before the actual start of fixing. Heat treatment is required. As a result, there is a serious drawback that a large amount of electric power is consumed even though the actual fixing by the heat fixing device is not performed. Sixth, in such a fixing device, the heat capacity of each component is designed to be small in order to improve efficiency and shorten the rise time. In this case, there is a tendency that the temperature of the portion of the heat roller where the paper does not pass (non-sheet passing portion) rises excessively, that is, so-called non-sheet passing portion temperature rise is likely to occur. It is considered that this is because if the cross-sectional area of the heat roller is reduced to reduce the heat capacity, apparent heat conduction in the longitudinal direction deteriorates, and it becomes difficult for partially retained heat to escape in the longitudinal direction. To be Therefore, in order to deal with the above, the present invention consumes less power, has a good response to the rise of heat generation, and does not have a thermal adverse effect on components and various components in the vicinity of the heat fixing unit. A heating roller with a simple structure that can properly perform heat fixing was adopted. This adopted heating roller is
Since the pressure roller is configured to generate heat in the pressed portion, in this configuration, not only the above-mentioned portion where the pressure roller for fixing is pressed but also the cleaning pad for cleaning the heating roller is pressed. It was predicted that the problem would occur in the part where the heat is generated and consumes unnecessary power.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a thermal fixing device capable of removing the residual toner on the heating roller without wasting electric power.

[0008]

In order to solve the above-mentioned problems, in the present invention, a stationary member is rotatably supported by a shaft, and a plurality of through-holes are formed on the rotary shaft so as to be substantially concentric therewith. A cylindrical insulating elastic layer, a cylindrical electrode layer having concentric fitting into the insulating elastic layer and having respective electrode portions inserted into the through holes, respectively, and the electrode layer having the insulating elastic layer interposed therebetween. A heating roller formed of a cylindrical resistance layer fitted substantially concentrically with the insulating elastic layer so as to face each other, and a nip portion for holding a sheet under contact with the heating roller. As described above, the pressure roller is rotatably supported by the stationary member, and power supply means for supplying power between the electrode layer and the resistance layer of the heating roller. Caused by contact with the roller With the elastic deformation of the portion corresponding to the nip portion, the portions of the electrode layer and the resistance layer corresponding to the nip portion are electrically connected to each other at the electrode portions corresponding thereto, thereby The thermal fixing device for generating heat necessary for fixing in the section is characterized by further including the following means. That is, in the first aspect of the present invention, a removing unit that is pressure-bonded to the outer periphery of the heating roller to remove dirt on the outer periphery, an attaching / detaching unit that presses and separates the removing unit from the heating roller, and the electric power. And a control unit that separates the removal unit from the heating roller by the attachment / detachment unit while power is being supplied to the heating roller by the supply unit. In the second aspect of the present invention,
A removing unit that is pressure-bonded to the outer periphery of the heating roller to remove dirt on the outer periphery, an attaching / detaching unit that presses and separates the removing unit from the heating roller, and a heating-roller driving unit that rotates the heating roller. A sheet conveying means for conveying a sheet to the heating roller, and a state in which the removing / attaching means is controlled and the removing means is pressed against the heating roller.
The heating roller driving means is controlled to rotate the heating roller to remove the dirt on the heating roller, and the feeding / separating means is controlled to remove the removing means while the electric power is being supplied to the heating roller. Control means for separating from the heating roller, wherein at the time of fixing the next paper after fixing one paper, at least one rotation of the heating roller is performed in a state where the removing means is pressure-bonded, and then the heating is performed. And a control unit that controls the sheet conveying unit so that the sheet reaches the roller.

[0009]

With the above-described configuration of the present invention, the first
In the above aspect, while the control means controls the power supply means to supply electric power to the heating roller to thermally fix the sheet by the heating roller, the attaching / detaching means is controlled to remove the removing means from the heating roller. Separate. Therefore, when the removing means is pressure-bonded to the heating roller which is supplied with power, the electrode layer and the resistance layer of the heating roller come into contact with each other at the pressure-bonding portion, and a current flows between the electrode layer and the resistance layer. It is possible to prevent waste of power. Further, by configuring the present invention in this way, in the second aspect, the control means controls the heating roller driving means in a state in which the removing means is pressed against the heating roller by controlling the attaching / detaching means. Then, the heating roller is rotated to remove the stain on the heating roller. On the other hand, while the electric power supply unit is controlled to supply electric power to the heating roller to thermally fix the sheet by the heating roller, the attaching / detaching unit is controlled to separate the removing unit from the heating roller. Then, when the paper is continuously fixed, after the fixing of the first paper is completed, at least the heating roller is rotated once while the removing means is pressed to remove the stain on the heating roller. Then, the sheet conveying means is controlled so that the sheet reaches the heating roller and the fixing of the next sheet is started. Therefore, it is possible to prevent the electric power from being wasted due to the electrode layer and the resistance layer of the heating roller coming into contact with each other due to the removal means being pressure-bonded to the heating roller which is supplied with the electric power. Further, even when the fixing is continuously performed, the fixing of the next sheet is started after removing the stains at least for one rotation of the heating roller, that is, the entire circumference of the heating roller. Therefore, the fixing quality is deteriorated by the residual toner. Does not occur.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross section of an example of a heat fixing device to which the present invention is applied, and FIG. 2 shows an appearance of the heat fixing device. ing. This heat fixing device has upper and lower covers 1 having a substantially U-shaped cross section.
0, 20 and each of these covers 10, 20
The respective openings are arranged so as to face each other. Further, the heat fixing device includes a heating roller 30 assembled in the cover 10 and a pressure roller 40 assembled in the cover 20, and the heating roller 30 is mounted on the inner wall of the cover 10 at the center shaft 31 with both bearings ( (Not shown) is rotatably supported coaxially.

The pressure roller 40 is constructed by forming an elastic roller portion 42 made of a heat-resistant elastic material such as silicon rubber on the outer periphery of a central shaft 41. The pressure roller 40 is rotatably attached to the cover 20. The outer peripheral surface of the elastic roller portion 42 is abutted against the outer peripheral surface of the heating roller 30. Further, since the outer peripheral surface of the elastic roller portion 42 is arranged so as to be pressed against the outer peripheral surface of the heating roller 30, both the contact portions of the pressure roller 40 and the heating roller 30 have a nip portion A (described later). 6) is formed.

In this heat fixing device, however, the toner 51 placed on the paper 50 is melted by the heat generated by the heating roller 30 as described later, so that the paper 5 is melted.
It is heat-fixed to 0. In this heat fixing, the heating roller 30 and the pressure roller 40 are rotated in the direction of the arrow shown in FIG. 1 so that the paper 50 is sequentially conveyed in the direction of the arrow shown. Therefore, the thermal fixing device described in this embodiment generally has two functions: a function of transporting the sheet 50 and a function of melting the toner 51 by heat and fixing the toner on the sheet 50. In such cases,
The pressure roller 40 has a central shaft 41 rotatably connected to a central shaft 31 of the heating roller 30 via a gear (not shown). In FIG. 1, reference numerals 60a and 60b respectively denote paper guides that guide the paper 50 to a predetermined position, and reference numerals 70a and 70b.
Reference numerals 0b respectively denote sheet discharge rollers that discharge the sheet 50 to the outside of the apparatus. Reference numeral 120 denotes a paper discharge detection sensor that detects that the paper has been fixed and discharged.

On the other hand, as shown in FIG.
A cleaning device 80 is arranged above. The cleaning device 80 includes a cleaning pad 81 made of felt or the like impregnated with silicon oil, a holder 82 for holding the cleaning pad 81, and an arm 83 for holding the holder 82. The cleaning pad 81 is pressed against the heating roller 30 to remove the toner remaining on the heating roller 30. The arm 83 is rotatably supported by a pin 85 of a support member 84 attached to the upper cover 10. In the substantially central portion of the arm 83,
A wing portion 83a is formed, and a compression spring 86 is arranged below the wing portion 83a to move the arm 83 into a pin 85.
Is applied in the counterclockwise direction, that is, in the direction of separating the cleaning pad 81 from the heating roller 30 in FIG. On the other hand, a tip portion 83b of the arm 83 is connected to a push-pull solenoid 87 via a spring 88, and a lower end portion of the solenoid 87 is fixed to the upper cover 10. This spring 88 is a force for rotating the arm 83 clockwise about the pin 85,
That is, a force is applied in the direction in which the cleaning pad 81 is pressed against the heating roller 30 side. As shown in FIG. 2, a pair of arms 83 is provided on the heat fixing device, and is configured to position the cleaning pad 81 having a length substantially equal to the length of the heating roller 30 in the longitudinal direction. The cleaning pad 81 has the above-mentioned length and thus cleans the entire fixing area of the heating roller 30. When the solenoid 87 is turned on by a signal from a control unit which will be described later, a plunger (not shown) is pulled in, and the arm 8 is opposed to the compression force of the compression spring 86 described above.
The cleaning pad 81 is pressed against the heating roller 30 side by rotating 3 in the clockwise direction. On the contrary, when the solenoid 87 is turned off, the plunger is pushed out and the arm 83 is rotated counterclockwise to move the cleaning pad 81 away from the heating roller 30. At this time, the compression spring 86 is adjusted so as to cooperate with the operation of the solenoid 87.

Next, the structure of the heating roller 30 is shown in FIG.
It will be described in detail with reference to FIGS. This heating roller 3
0 has two functions of conveying the sheet 50 and generating two heats in the nip portion A to melt the toner 51 and fix it on the sheet 50. The heating roller 30 is
As shown in FIG. 3, a central body 31 made of a metallic material is provided with a cylindrical base portion 32 concentrically supported on the outer periphery thereof. The base portion 32 is made of a slightly elastic insulating material such as rubber or resin. Has been formed. The heating roller 30 is
The cylindrical electrode layer 33 is provided, and the electrode layer 33 is mainly made of a metal conductive material such as aluminum and has a base portion 32.
Is concentrically fitted around the outer periphery of the. On the outer peripheral surface of the electrode layer 33, as shown in FIG.
Are discretely provided in a predetermined array. In such cases,
The electrode layer 33 and each electrode portion 33a can be electrically connected to each other. In this embodiment, each electrode portion 33a is formed of a heat-resistant metal material such as tungsten, which has excellent heat resistance and wear resistance, because its tip is exposed to high temperature and high pressure conditions. The respective electrode portions 33a are not limited to the columnar shape, and may be formed in various shapes such as a cubic columnar shape or a hemispherical shape, and each electrode portion 33a may be formed of the same material as the electrode layer 33. Alternatively, it may be formed integrally with the electrode layer 33.

The elastic layer 34 is formed of an insulating elastic material into a cylindrical shape, and the elastic layer 34 is concentrically fitted on the outer peripheral surface of the electrode layer 33 as shown in FIG. In this elastic layer 34, each cylindrical through hole 34a is formed so as to face each electrode portion 33a as shown in FIG. 4, and each electrode portion 33a is substantially concentric with each through hole 34a. Has been inserted. In such a case, each through hole 3
The depth of 4a is deeper than the height of each electrode portion 33a, and when the elastic layer 34 and the electrode layer 33 are adhered, the outer end surface of each electrode portion 33a and the outer surface of the elastic layer 34, that is, each penetration A gap is formed between the hole 34a and the outer end opening surface. The inner diameter of each through hole 34a is larger than the outer diameter of each electrode portion 33a.

The resistance layer 35 is made of a material in which carbon is dispersed in a polycarbonate film and is formed into a cylindrical shape having a film thickness of about 20 micrometers so as to have a predetermined volume resistance value. Are concentrically fitted to the outer peripheral surface of the elastic layer 34, as shown in FIG. The common electrode layer 36 is vacuum-deposited in a cylindrical shape with a thickness of 1000 angstrom to 0.2 mm from a material such as aluminum, and the common electrode layer 36 is concentric with the outer peripheral surface of the resistance layer 35. Is fitted to. The anti-fusing layer 37 is formed of a material such as tetrafluoroethylene into a cylindrical shape, and the anti-fusing layer 37 is concentrically fitted on the outer peripheral surface of the common electrode layer 36. The outer peripheral surface of the heating roller 30 is configured to prevent the toner 51 from being fused to the outer peripheral surface of the heating roller 30 during heat fixing. However, the fusion preventing layer 37 has a right end portion 37a shown in FIG. 5 so that each right end portion of the elastic layer 34, the resistance layer 35, and the common electrode layer 36 is exposed so that the right end portion 33b of the electrode layer 33 is exposed. The positive electrode 38a is in contact with the right end 33b of the electrode layer 33 at its tip. Further, the fusion preventing layer 37 is short so as to expose the left end portion 36a of the common electrode layer 36 at the left end portion 37b shown in FIG. The negative electrode 38b is in contact with its tip. Both electrodes 38a and 38b are fixed in place at their bases.

In the heating roller 30 constructed as described above, since the heating roller 30 is pressed by the pressure roller 40 at the contact portion with the outer peripheral portion of the pressure roller 40, the elastic layer 34 is the same. Upon receiving a pressing force, the contact portion is elastically deformed and crushed. Similarly, the elastic roller portion 42 of the pressure roller 40 is
It is elastically deformed by being pressed and is crushed at the contact portion with the heating roller 30. As a result, a nip portion A is formed in the contact portion between the heating roller 30 and the pressure roller 40 as shown in FIG. 6 so as to secure the area and pressure required for heat fixing.

In such a case, since the elastic deformation of the elastic layer 34 does not occur at the non-contact portion between the heating roller 30 and the pressure roller 40, each electrode portion 33 of the electrode layer 33.
The a and the resistance layer 35 are maintained in a non-contact state with each other (see FIG. 7A). Therefore, a direct current does not flow between the electrode layer 33 and the resistance layer 35. On the other hand, in the nip portion A, since the elastic layer 34 is crushed by its elastic deformation at the contact portion between the heating roller 30 and the pressure roller 40, each electrode portion 33a of the electrode layer 33 and the resistance layer 35 are Maintaining mutual contact (Fig. 7 (B))
reference). Therefore, the respective electrode portions 33a of the electrode layer 33 and the resistance layer 35 are in a state capable of mutually conducting electricity in the region corresponding to the nip portion A. The central axis 31 and the base portion 3 described above
The opposing surfaces of the electrode layer 33, the elastic layer 34, the resistance layer 35, the common electrode layer 36, and the fusion preventing layer 37 are uniformly adhered by an appropriate adhesive or vapor deposition force.

Next, the structure of the electric circuit of the device of the present invention will be described with reference to FIG. Solenoid drive circuit 150
Performs the operation of turning on and off the solenoid 87 in response to a control signal from the control unit 100 including a microcomputer. As shown in FIG. 1, the paper discharge detection sensor is placed in the vicinity of the paper discharge rollers 70a and 70b of the thermal fixing device, detects that the fixed paper is discharged, and outputs a detection signal to the controller 100. It is configured to output to. The heating roller drive circuit 130 generates a signal for driving the heating roller 30 shown in FIG. 1 based on a control signal from the control unit 100. Further, the paper feed roller drive circuit 160 is
Paper to which toner was attached in the pre-fixing stage, that is,
The control unit outputs a signal for driving a paper feed roller (not shown) that conveys the paper, to which the toner image has been transferred in a transfer device (not shown), to the thermal fixing device shown in FIG. 1 for fixing the toner. It is generated based on a control signal from 100.

The timer 140, in the control unit 100,
As will be described later, it is provided to give an instruction to the heating roller drive circuit 130 and measure the time from the start of rotation of the heating roller 30 to one rotation. The power supply circuit 110 has its positive terminal connected to the positive electrode 38a and its negative terminal connected to the negative electrode 38b. Under the control of the control unit 100, the power supply circuit 110 controls the current between the exposed end portion 33b of the electrode layer 33 and the exposed end portion 36a of the common electrode layer 36 of the heating roller 30 via both electrodes 38a and 38b. To do.

The control unit 100 executes a computer program according to the flow chart shown in FIG. 9 to perform arithmetic processing required for controlling the power supply circuit 110 and the solenoid drive circuit 150. The computer program described above is stored in advance in a ROM (not shown) of the control unit 100.

In the present embodiment configured as described above,
A case in which heat fixing and cleaning of the heat fixing device are actually performed by the device of the present invention will be described. When the device of the present invention is put into operation, the control unit 100 starts executing the computer program according to the flowchart of FIG. First, in step 11, the control unit 100 sends a control signal to the paper feed roller drive circuit 160 to start the conveyance of the paper to the thermal fixing device side. Next, at step 12, a signal is sent to the solenoid drive circuit 150 to turn on the solenoid 87. As a result, as shown in FIG.
Is the arm 8 against the compression force of the compression spring 86 described above.
By rotating 3 in the clockwise direction, the cleaning pad 81 is pressed against the heating roller 30 side. In this state, in step 13, a signal is output to the heating roller drive circuit 130 to rotate the heating roller 30, and the heating roller 30 is rotated.
The removal of the above residual toner is started. At the same time, the timer 140 is reset and the time from the start of rotation of the heating roller 30 is measured. Then, in the judgment step 14, it is judged whether or not the heating roller 30 has rotated once, by referring to the timer 140, based on whether one rotation time has elapsed from the start of the rotation, and if it has rotated once (the judgment step). 14 is Ye
In step s), the process proceeds to step 15. This heating roller 30 is 1
By rotating, the surface of the heating roller 30 is cleaned over the entire circumference. In step 15, the control unit 10
0 sends a signal to the solenoid drive circuit 150 to turn off the solenoid 87. As a result, the solenoid 87 shown in FIG. 1 rotates the arm 83 counterclockwise to separate the cleaning pad 81 from the heating roller 30. The cleaning of the heating roller 30 is completed by the above processing, and subsequently, the processing for fixing is started from step 16. It should be noted that in the present embodiment, the paper feed roller is set so that the time from the start of the conveyance of the paper in step 11 to the arrival of the paper at the heat fixing device is longer than the time for one rotation of the heating roller 30. Since the conveyance path between the heat fixing device and the heat fixing device is set, the sheet reaches the heat fixing device after the energization of the heating roller 30 is started in step 16 described later, that is, after the preparation for the heat fixing is completed.

First, in step 16, the control unit 10
0 outputs an application command signal required to apply the DC voltage to the power supply circuit 110. At this time, in step 13 described above, the heating roller 30 is driven by the heating roller drive circuit 130 to rotate together with the pressure roller 40, and in the heating roller 30, the nip portion A is formed by the heating roller 30 and the pressure roller 40. Has been done. In such a case, in the nip portion A, as shown in FIG. 7B, each electrode portion 33a of the electrode layer 33 is connected to each corresponding portion of the resistance layer 35 through each through hole 34a of the elastically deformed elastic layer 34. Are in contact. Therefore, in step 16 described above, the power supply circuit 110 corresponds to the nip portion A between the right exposed end portion 33b of the electrode layer 33 of the heating roller 30 and the left exposed end portion 36a of the common electrode layer 36 through the electrodes 38a and 38b. When a DC voltage is applied in the area, the power supply circuit 110, the positive electrode 38a, the electrode layer 33 of the heating roller 30, each electrode portion 33a (the electrode portion corresponding to the nip portion A), the resistance layer 35.
Also, a direct current flows through a closed circuit composed of the negative electrode 38b. In such a case, in the area corresponding to the nip portion A, the direct current as described above flows into the resistance layer 35, and the resistance layer 35 generates heat according to the resistance value.

After that, the paper 50 conveyed by the paper feed roller reaches the heat fixing device, and the paper 50 is heated by the heating roller 3.
0 and the nip portion A according to each rotation of the pressure roller 40.
The thermal energy generated by the heating roller 30 is conveyed between the resistance layer 35 and the common electrode layer 36 and the fusion preventing layer 37 through a region corresponding to the nip portion A while being conveyed in a state of being sandwiched between the sheet 50. Be transmitted to. Therefore, the transferred heat energy is used for melting the toner 51 on the sheet 50 at the nip portion A, and the heat fixing is performed.

In such a case, since the common electrode layer 36 and the fusion preventing layer 37 are both formed of extremely thin layers, the thermal resistance of the common electrode layer 36 and the fusion preventing layer 37 is extremely small. Therefore, the thermal energy generated in the resistance layer 35 can be very efficiently transferred to the outer surface of the heating roller 30.
As a result, the heat-fixable state described above is quickly achieved, and the waiting time for starting heat-fixing can be shortened to the minimum. Further, since the heat generated by the heating roller 30 and its transmission are limited to the nip portion A, it is of course possible to extremely reduce the thermal adverse effect on the other components of the heat fixing device, and of course, the power consumption. The amount can be extremely reduced, and this type of heat fixing device can be made compact.

Next, in a judgment step 17, it is judged based on the output from the paper discharge detection sensor 120 whether or not the fixing is completed. When the fixing is completed and there is an output from the paper discharge detection sensor 120, the determination step 17 becomes Yes and the process proceeds to step 18, and the control unit 100 causes the heating roller 30
The drive stop command signal required to stop the drive is output to the heating roller drive circuit 130, and the application stop command signal required to stop the DC voltage application by the power supply circuit 110 is output to the power supply circuit 110 (step 19). Therefore, the heating roller 30 stops rotating together with the pressure roller 40,
Further, the power supply circuit 110 stops the application of the DC voltage to the heating roller 30. Then, in a determination step 20, it is determined whether continuous fixing is performed, that is, whether fixing is performed on the next sheet. Here, when fixing the next sheet, the determination step 20 becomes Yes and the process returns to step 11 to send a control signal to the sheet feed roller drive circuit 160 to be the next subject to be fixed to the heat fixing device side. Start feeding the paper. Next, in step 12, the solenoid drive circuit 1
A signal is sent to 50 to turn on the solenoid 87, and the cleaning pad 81 is pressed against the heating roller 30 side. In this state, in step 13, the heating roller 30 is rotated to start removing the residual toner on the heating roller 30. Then, in the judgment step 14, the heating roller 30 is set to 1
It is judged whether or not it has been rotated, and if it has rotated once (Yes in the judgment step 14), the routine proceeds to step 15. Step 1
At 5, the solenoid 87 is turned off and the arm 83 is rotated counterclockwise to separate the cleaning pad 81 from the heating roller 30. As a result, the cleaning of the entire circumference (one circumference) of the heating roller 30 is completed, and the fixing operation after step 16 is subsequently performed. As described above, in this embodiment, even when the fixing is continuously performed, the fixing of the next sheet is started after the stain is removed at least for one rotation of the heating roller, that is, the entire circumference of the heating roller is removed. The fixing quality does not deteriorate due to the residual toner.

Further, in this embodiment, the cleaning pad 81 is separated from the heating roller 30 while the electric power is supplied to the heating roller and the sheet is thermally fixed by the heating roller. Therefore, when the cleaning pad 81 is pressure-bonded to the heating roller 30 which is supplied with electric power, the electrode layer 33 and the resistance layer 35 of the heating roller 30 are brought into contact with each other at the pressure-bonded portion, and the electrode layer 33 and the resistance layer 35 are connected. It is possible to prevent current from flowing to and from the layer 35 and wasting power. Further, by separating the cleaning pad 81 while the heating roller 30 is being heated, deterioration of the cleaning pad 81 due to heat can be avoided.

In the embodiment described above, the time from when the paper feed roller starts conveying the paper to when the paper reaches the heat fixing device is longer than the time for one rotation of the heating roller 30. Since the conveyance path between the sheet feeding roller and the thermal fixing device is set in step 11, the heating roller 30 is driven and the cleaning of the heating roller 30 is started in step 13 after the conveyance of the sheet in step 11 is started. . However, if the time required to convey to the heat fixing device is shorter than the time required for one rotation of the heating roller 30, the heating roller 30 is driven to start cleaning, and then the conveyance of the sheet is controlled to start. Need to do. Also,
In the above-described embodiment, the cleaning pad 81 is brought into contact with and separated from the heating roller 30 by the arm 83 and the solenoid 87, but it goes without saying that various mechanisms can be used to bring the cleaning pad 81 into contact with and separate from the heating roller 30.

[0029]

As a result of the above-described structure and operation of the present invention, the thermal energy generated in the portion of the resistance layer corresponding to the nip portion is transferred to the sheet through the area corresponding to the nip portion. . Therefore, the transferred heat energy is used for melting the toner on the paper at the nip portion, and the heat fixing is possible. As a result, as the above-mentioned sheet is conveyed, the heat fixing of the toner on the sheet is smoothly performed with high quality. In such a case, the thermal energy generated in the resistance layer is transferred to the paper through the nip portion,
A very efficient heat transfer is possible. As a result, the heat-fixable state described above is quickly achieved, and the waiting time for starting heat-fixing can be shortened to the minimum. Further, as described above, since the heat generation and the transmission thereof are limited to the nip portion, it is needless to say that the thermal adverse effect given to other constituent members of the heat fixing device can be made extremely small.
The power consumption can be extremely reduced, and this type of heat fixing device can be provided as a reliable heat fixing device with a compact structure. Further, according to the present invention, even when the fixing is continuously performed, the fixing of the next sheet is started after the stain is removed at least for one rotation of the heating roller, that is, after the entire circumference of the heating roller is removed. No deterioration of quality occurs. Further, according to the present invention, the cleaning pad is configured to be separated from the heating roller while the electric power is supplied to the heating roller and the heat fixing of the sheet is performed. When the cleaning pad is pressure-bonded, it is possible to prevent the electrode layer and the resistance layer of the heating roller from coming into contact with each other, thereby preventing a current from flowing between the electrode layer and the resistance layer and wasting power.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view of the heat fixing device shown in FIG.

FIG. 3 is an enlarged cross-sectional view of the heating roller of FIG.

FIG. 4 is an enlarged perspective view of an essential part showing a configuration of an electrode layer and an elastic layer of the heating roller of FIG.

FIG. 5 is a perspective view showing the appearance of a heating roller.

FIG. 6 is an enlarged cross-sectional view of an essential part for showing a nip portion formed by a heating roller and a pressure roller of FIG.

7 is an enlarged cross-sectional view of an essential part showing a state of an electrode layer, an elastic layer and a resistance layer in a non-nip portion taken along line 8A-8A in FIG. 6 and an electrode in a nip portion taken along line 8B-8B in FIG. FIG. 3 is an enlarged cross-sectional view of a main part showing the states of a layer, an elastic layer and a resistance layer.

FIG. 8 is an electric circuit diagram for cleaning and heat fixing the heating roller.

9 is a flowchart showing the operation of the control unit of FIG.

[Explanation of symbols]

 30 heating roller 31 central axis 33 electrode layer 34 elastic layer 35 resistance layer 40 pressure roller 50 paper 51 toner 81 cleaning pad 87 solenoid 100 controller 110 power circuit 130 heating roller drive circuit A nip section.

Claims (2)

[Claims] 1. A cylindrical insulating elastic layer, which is rotatably supported by a stationary member and is provided substantially concentrically with the rotating shaft to form a plurality of through holes, and the insulating elastic layer. A cylindrical electrode layer having concentrically fitted electrode portions inserted into the through holes, respectively, and substantially concentric with the insulating elastic layer so as to face the electrode layer through the insulating elastic layer. And a pressure roller rotatably supported by the stationary member so as to form a nip portion for sandwiching a sheet under the contact with the heating roller. And a power supply unit that supplies power between the electrode layer and the resistance layer of the heating roller, and a portion of the portion corresponding to the nip portion generated by the contact between the heating roller and the pressure roller. With elastic deformation,
Thermal fixing for generating heat necessary for fixing in the nip portion by electrically connecting respective portions of the electrode layer and the resistance layer corresponding to the nip portion to each other in corresponding electrode portions. A device for removing the dirt on the outer circumference of the heating roller by pressing the outer circumference of the heating roller, a detaching means for pressing and removing the removing means from the heating roller, and the heating by the power supply means. While powering the rollers,
And a control unit that separates the removal unit from the heating roller by the attachment / detachment unit. 2. A cylindrical insulating elastic layer, which is rotatably supported by a stationary member and is provided substantially concentrically with the rotating shaft to form a plurality of through holes, and the insulating elastic layer. A cylindrical electrode layer having concentrically fitted electrode portions inserted into the through holes, respectively, and substantially concentric with the insulating elastic layer so as to face the electrode layer through the insulating elastic layer. And a pressure roller rotatably supported by the stationary member so as to form a nip portion for sandwiching a sheet under the contact with the heating roller. And a power supply unit that supplies power between the electrode layer and the resistance layer of the heating roller, and a portion of the portion corresponding to the nip portion generated by the contact between the heating roller and the pressure roller. With elastic deformation,
Thermal fixing for generating heat necessary for fixing in the nip portion by electrically connecting respective portions of the electrode layer and the resistance layer corresponding to the nip portion to each other in corresponding electrode portions. An apparatus for removing the dirt on the outer circumference of the heating roller by pressing the outer circumference of the heating roller, a detaching means for pressing and separating the removing means from the heating roller, and rotating the heating roller. Heating roller driving means, a sheet conveying means for conveying a sheet to the heating roller, and the heating roller driving means in a state where the removing means is pressed to the heating roller by controlling the attaching / detaching means. The heating roller is controlled to rotate to remove dirt on the heating roller, and while the power supply means is supplying power to the heating roller, the attaching / detaching means is controlled to move the removing means to the heating roller. When fixing the next sheet of paper after fixing the first sheet of paper, at least the heating roller is rotated once with the removing means in pressure contact, and then the sheet of paper is transferred to the heating roller. And a control unit that controls the sheet conveying unit so that the sheet arrives at the heat fixing device.