JPH0973245A - Heating device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability-reliability of a device, to save an electric power, and to improve a heating performance (fixing performance) and a accuracy of the temp. control, by preventing non-paper passing part heat-up phenomena, in respect to a heating device of a magnetic guide heating type. SOLUTION: This heating device is constituted that a magnetic metal member 117 is made magnetic induction heating by imparting high frequency field onto the magnetic metal member, by the heat of which a material to be heated S is heated. In the case the material to be heated is not present on the material to be heated heating position N of the device, the time for stopping or reducing is provided, and this time is made variable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic (electromagnetic) induction heating type heating device and an image forming apparatus including the heating device as an image heating device.

[0002]

2. Description of the Related Art Conventionally, for example, in an image heating apparatus in an image forming apparatus, that is, in an image forming apparatus such as a copying machine, a laser beam printer, a facsimile, a microfilm reader printer, an image display (display) device, a recording machine, etc. The recording medium (transfer material sheet, transfer material sheet,
An unfixed developer image corresponding to the target image information formed by the indirect (transfer) method or the direct method on the surface of the electro-fax sheet, electrostatic recording sheet, printing sheet, printing paper, etc. is recorded on the surface of the recording medium. As a device for performing heat fixing processing as a permanently fixed image, a heat roller type device using a heat roller or a film heating type device is often used.

(A) A heat roller type apparatus is composed of a metal heat roller having a heating element such as a halogen heater therein and a pressure roller having elasticity for pressure contact with the metal heat roller. An image is heated and pressure-fixed by passing a recording medium, which is a material to be heated, through a fixing nip portion which is a portion.

However, in such a heat roller system, since the heat capacity of the roller is large, it takes a very long time to raise the temperature of the roller surface to a predetermined fixing temperature.
Therefore, in order to quickly execute the image output operation, the roller surface must be controlled to a certain standby temperature even during non-image output.

(B) A film heating type apparatus is disclosed in JP-A-63 / 1988
-313182 / JP 2-157878 / JP 4-
It is proposed in Japanese Patent Laid-Open No. 44075, Japanese Patent Laid-Open No. 4-204980, and the like. That is, it has a heating body (generally referred to as a ceramic heater, hereinafter referred to as a heater) and a heat resistant film that moves in close contact with the heater, and a material to be heated is brought into close contact with the heater via this film to form a heater together with the film. It is a heating device that moves the position and applies the heat energy of the heater to the material to be heated through the film. It has a pressurizing member that brings the film and the object to be heated into close contact with the heater.

The image fixing operation is performed by introducing and passing a recording medium as a material to be heated between the film and the pressing member in the fixing nip portion formed by pressing the heater and the pressing member with the film interposed therebetween. This is performed by heating the surface of the recording medium on which the visible image is carried with a heater through the film.

In such a film heating type apparatus,
Since a heater having a low heat capacity can be used, the wait time can be shortened (quick start) as compared with the heat roller method. Further, since the quick start is possible, it is not necessary to raise the temperature of the heater in advance, so that it is possible to reduce the power consumption and prevent the temperature rise inside the machine.

(C) Further, the present applicant has previously proposed a magnetic induction heating type heating apparatus (Japanese Patent Application Nos. 6-163284 and 16328).
5, 165898, 168773, 168774, 180962, 188331, 199064, 19906
5, 205960, 225876, 232038, 239385, 292117, 292118, 303027
No.).

This heating device is a heating device for applying a high-frequency magnetic field to a magnetic metal member to cause the magnetic metal member to generate heat by magnetic induction and heat the material to be heated by the heat. More specifically, a member forming the nip portion and a magnetic metal member (magnetic induction heating member, conductive member, induction magnetic material, magnetic field absorption conductive member) that generates heat by high-frequency magnetic field action on at least one of the members forming the nip portion. (Also referred to as a material) and a high-frequency magnetic field generating means for applying a high-frequency magnetic field to the magnetic metal member, and the nipped portion is set as a heating position for the heated material, and the heated material is nipped and conveyed to be heated. It is an apparatus for heat-treating a material by heat generation of a magnetic metal member. That is, an eddy current is generated in the magnetic metal member by utilizing magnetic induction, and heat (Joule heat) is generated by the electric resistance of the magnetic metal member to heat the material to be heated in the nip portion. It has the advantage of being more excellent in thermal efficiency than the film heating type heating device of).

[0010]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
One of the problems common to both film heating type and magnetic induction heating type heating devices is that when a small-sized material to be heated is continuously fed and heat-treated, The so-called "non-sheet-passing portion temperature rise phenomenon" (partial heating state of the heating portion) occurs in which the temperature is higher than the sheet-passing area portion, which causes heat loss in the device and impairs the durability of the device. This is one of the causes of poor fixing and high temperature offset in the heating device.

The present invention particularly aims to improve the durability and reliability of the heating apparatus of the magnetic induction heating system of the above (c) by suppressing the temperature rise phenomenon of the non-sheet passing portion, Power saving, improvement of heating performance (fixing performance),
The purpose is to improve the accuracy of temperature control.

[0012]

The present invention is a heating device and an image forming apparatus characterized by the following configurations.

(1) A heating device for applying a high-frequency magnetic field to a magnetic metal member to cause the magnetic metal member to generate heat by magnetic induction and heat the material to be heated by the heat. A heating device, wherein a time for stopping or reducing the heat generation of the magnetic metal member is provided in the absence of the above, and this time is variable.

(2) When the material to be heated is continuously conveyed to the apparatus, the time for stopping or reducing the heat generation of the magnetic metal member is variable between the material to be heated and the material to be heated. The heating device according to (1).

(3) As a means for determining the time for stopping or reducing the heat generation of the magnetic metal member, the time for stopping or reducing the heat generation of the magnetic metal member is provided in accordance with the predetermined number of consecutively conveyed materials to be heated. (2) The heating device according to (2).

(4) As a means for determining the time for stopping or reducing the heat generation of the magnetic metal member, the heat generation of the magnetic metal member is determined according to the temperature decrease rate when the heat generation of the magnetic metal member is stopped or reduced. The heating device according to (1) or (2), characterized in that a time for stopping or reducing is provided.

(5) Means for detecting the electric power applied to the high frequency magnetic field generating field coil for maintaining the magnetic metal member at a predetermined temperature as means for determining the time for stopping or reducing the heat generation of the magnetic metal member. And at least one reference power is provided, and a time for stopping or reducing heat generation of the magnetic metal member is provided depending on whether the detection power is higher or lower than the reference power (1) or ( The heating device according to 2).

(6) As a means for determining the time for stopping or reducing the heat generation of the magnetic metal member, the size of the material to be heated to be conveyed is provided, and the heat generation of the magnetic metal member is stopped according to the size of the material to be heated. Alternatively, the heating device according to (1) is characterized in that a time for reducing the heating time is provided.

(7) As a means for determining the time for stopping or reducing the heat generation of the magnetic metal member, the heat generation amount of the magnetic metal member is temporarily increased when the material to be heated does not exist at the heating position. The heating device according to (1), characterized in that the time for stopping or reducing the subsequent heat generation is determined based on the amount of temperature rise of the magnetic metal member during that time.

(8) As a means for determining the time for stopping or reducing the heat generation of the magnetic metal member, the next step is determined according to the temperature rising rate when the heat generation of the magnetic metal member is stopped or reduced and then reheated. The fixing device according to (1), characterized in that a time for stopping or reducing heat generation for the material to be heated is determined.

(9) A heating device for applying a high-frequency magnetic field to a magnetic metal member to cause the magnetic metal member to generate heat by magnetic induction and heat the material to be heated by the heat, and has a temperature detecting means for the magnetic metal member, The means for applying a high-frequency current to the high-frequency magnetic field generating field coil operates so that the temperature detected by the temperature detecting means is maintained at a constant temperature, and when there is no heated material at the heated material heating position of the apparatus, A magnetic metal member temperature control means is provided for stopping the operation of the means for applying a high frequency current to the field coil and changing the control temperature of the magnetic metal member in accordance with the temperature change of the magnetic metal member at that time. A heating device, wherein the time during which the operation of the means for applying a high-frequency current to the coil is stopped is longer than the time during which the temperature change of the magnetic metal member is detected.

(10) A heating device for applying a high-frequency magnetic field to a magnetic metal member to cause the magnetic metal member to generate heat by magnetic induction and heat the material to be heated by the heat, and has a temperature detecting means for the magnetic metal member, The means for applying a high-frequency current to the high-frequency magnetic field generating field coil operates so that the temperature detected by the temperature detecting means is maintained at a constant temperature. The high frequency magnetic field generating field coil has magnetic metal member temperature control means for supplying constant power to the magnetic field generating field coil and changing the control temperature of the magnetic metal member in accordance with the temperature change of the magnetic metal member at that time. A heating device characterized in that the time during which the operation of the means for applying a high-frequency current is stopped is longer than the time during which the temperature change of the magnetic metal member is detected at that time.

(11) A heating device for applying a high-frequency magnetic field to a magnetic metal member to cause the magnetic metal member to generate heat by magnetic induction and heat the material to be heated by the heat, and has a temperature detecting means for the magnetic metal member, The means for applying a high frequency current to the high frequency magnetic field generating field coil operates so that the temperature detected by the temperature detecting means is maintained at a constant temperature T ₁ , and when there is no material to be heated in the heated material heating position of the apparatus. 'controls the magnetic metal member to, from temperatures T ₁ the temperature T' lower temperature T than the temperature T ₁ of the next object when it has reached the temperature T 'within a predetermined time after when switching control to The control temperature of the magnetic metal member with respect to the heating material is T _1, and when the temperature does not reach within a predetermined time, the control temperature of the magnetic metal member with respect to the next material to be heated is T ₂ lower than T _1. Heating device.

(12) Apply a high frequency magnetic field to the magnetic metal member
The magnetic metal member to generate heat by magnetic induction,
A heating device for heating a heating material, which is the temperature of the magnetic metal member.
Frequency detection means, high frequency magnetic field generation field coil
The means for applying the current has a constant temperature detected by the temperature detecting means.
Temperature T₁ To maintain the temperature of
When there is no material to be heated at the heat position, the temperature T₁ Than
Control and control the magnetic metal member to a low temperature T '
A certain control temperature that is preset from the time when the temperature reaches T '
Time t until the time reaches
If it is longer than the fixed time, the magnetic gold for the next heated material
The control temperature of the metal member is T ₁ Lower temperature T₂ And time t
Is less than the specified time, the magnetism to the next heated material
The control temperature of the metal member is T₁ Heating characterized by
apparatus.

(13) A heating device for applying a high-frequency magnetic field to a magnetic metal member to cause the magnetic metal member to generate heat by magnetic induction and heat the material to be heated by the heat. The electric power supplied to the high frequency magnetic field generating field coil is controlled by High and Low2 values when the magnetic material does not pass through, and based on the temperature ripple of the magnetic metal member at that time, the material to be heated next enters the position to be heated. A heating device for determining a control temperature of a magnetic metal member with respect to.

(14) A heating device for applying a high-frequency magnetic field to a magnetic metal member to cause the magnetic metal member to generate heat by magnetic induction and heat the material to be heated by the heat. Control the power supplied to the high-frequency magnetic field generating field coil by High and Low2 values when not passing through, and based on the temperature change rate at High or Low, the heating target enters the heating target material heating position next. A heating device for determining a control temperature of a magnetic metal member with respect to a material.

(15) A heating device for applying a high-frequency magnetic field to a magnetic metal member to cause the magnetic metal member to generate heat by magnetic induction and heat the material to be heated by the heat. Control the electric power supplied to the high frequency magnetic field generating field coil when it is not passing through, by the High and Low2 values, and the temperature to be heated next enters the heating position based on the peak or bottom of the temperature ripple of the magnetic metal member at this time. A heating device for determining a control temperature of a magnetic metal member with respect to a material.

(16) Of the roller pairs pressed against each other,
At least one of the rollers is a magnetic metal roller, and inside the magnetic metal roller, a high frequency magnetic field generating field coil and an induction magnetic material that couples to a main magnetic flux generated in the field coil are provided. A means for applying a high-frequency current is connected to the field coil, and by applying a high-frequency magnetic field to the metal surface of the magnetic metal roller facing the field coil, magnetic induction heat is generated in the magnetic metal roller, (1) to (15) characterized in that the nip portion of the pressure contact roller pair is set as a heating position for the material to be heated and the material to be heated is nipped and conveyed to the nip portion to heat the material to be heated by heat generated by the magnetic metal roller. ) The heating device according to any one of 1).

(17) A member that forms a nip portion, a magnetic metal member that magnetically generates heat by the action of a high frequency magnetic field on at least one member side of the nip portion forming member, and a high frequency magnetic field applied to the magnetic metal member at the nip portion. A high-frequency magnetic field generating means for operating the heating target material, the nip portion is set as a heating position for the heating target material, and the heating target material is sandwiched and conveyed in the nip portion to heat the heating target material by heat generated by the magnetic metal member. The heating device according to any one of (1) to (15).

(18) The material to be heated is a recording medium carrying an image to be heat-treated, and the apparatus is an image heating device for heat-processing the image on the recording medium (1).
The heating apparatus according to any one of (17) to (17).

(19) The image heating process is a heat fixing process of an unfixed image on the recording medium (1)
The heating device according to 8).

(20) A means for forming an image on a recording medium, and an image heating device for heating the image on the recording medium from the side of the image forming means by the heating device according to any one of (1) to (19). An image forming apparatus comprising:

(21) The image forming apparatus according to (20), wherein the means for forming an image on the recording medium is an electrophotographic process.

(22) The image heating process is a heat fixing process of an unfixed image on the recording medium (2)
The image forming apparatus according to 0).

<Operation> As described above, the heating apparatus of the magnetic induction heating system uses the magnetic metal member as a heating body to generate an eddy current in the magnetic metal member by using the magnetic induction to generate an electric resistance of the magnetic metal member. Generate heat (Joule heat),
This is a method for heating a material to be heated by the heat of the magnetic metal member (hereinafter referred to as a heating body) as a heating body at a heating position, which is obtained by quickly raising the heating body to a target predetermined temperature and then performing a quick start. Excellent (reduction of wait time).

According to the present invention, in such a heating apparatus of the magnetic induction heating system, when the material to be heated does not exist at the heating target material heating position of the apparatus or when the material to be heated is continuously conveyed to the apparatus. Between the heating material and the material to be heated (paper interval) (when paper is not passing, when image fixing device is not fixing), allow time to stop or reduce heat generation of the magnetic metal member as the heating element. The temperature control corresponding to the heating state of the heating element, that is, the low temperature control is performed, whereby the optimum power control can be always realized for the high-frequency magnetic field generating means, and the following effects can be obtained.

.. By means of controlling the heat generation of the heating element, a non-heating state is created to stop the heat generation of the heating element when there is no paper passing, such as between the sheets of continuous feeding of the material to be heated. By changing the input power required to maintain the temperature control, the temperature decrease rate of the heating element after the heating of the heating element is stopped, and the signal of the size of the material to be heated When the heating material is continuously fed, the temperature rise in the non-sheet passing area of the heating element can be suppressed, and in the image heating and fixing device, it is possible to secure the fixability of the toner image even when the device is cold. Can construct a high-performance fixing system.

.. The heating temperature of the heating body surface when the next material to be heated comes is determined by forcibly stopping the heat generation of the heating body and watching the descending speed of the heating body surface, or by supplying a constant power and watching the rising speed. The temperature control method is adopted, and by making the time to stop the heat generation of the heating element or to supply constant power longer than the time to detect the descending speed or the rising speed of the heating element surface, it is possible to eliminate false detection of control. Even if the device is used in such a mode, the temperature of the heating element can be kept constant, and in the image heating and fixing device, fixing failure or
High temperature offset can be prevented.

.. The control temperature of the heating element between the sheets is made lower than the temperature that the heated material controls while passing through the heating position,
When the control temperature between the sheets falls within a predetermined time, a Flag is set in the control sequence and this Flag is set.
If is standing, the entire device such as the heating body is cold, so the control temperature for the next heated material is the same as the previous heated material, and if Flag is not standing, lower the control temperature of the heating body. Thus, in the image heating and fixing device, it is possible to prevent the occurrence of offset and fixing failure.

.. By changing the temperature of the heating element based on the temperature change detected when the heating element generates heat or the temperature change detected when the heating element does not generate heat, the temperature of the heating element is kept constant no matter what timing the device is used. In the image heating and fixing device, defective fixing and high temperature offset can be prevented.

.. When the heating rate is raised to a predetermined temperature with the amount of electric power controlled by the wave number control, the heating rate is detected, and if the subsequent various control values are determined according to that rate, the heating rate detection time is set. By equalizing the time required for one cycle of the fundamental wave number of the wave number control, the error in speed detection can be reduced and the control after rising can be performed more accurately.

[0042] By changing to low temperature control between the sheets, the power consumption is reduced and the temperature inside the machine is lowered.

. Since the time for energizing the high frequency magnetic field generating means is reduced, the life of the device is extended and the reliability is improved.

[0044] As compared with a conventional heating device such as a heat roller system, a special means structure for extending the life of the device is not required, so that an increase in product cost can be prevented.

[0045]

BEST MODE FOR CARRYING OUT THE INVENTION

<First Embodiment> (FIGS. 1 to 9) (1) Example of image forming apparatus (FIG. 1) FIG. 1 is a schematic configuration diagram of an example of the image forming apparatus. The image forming apparatus of this example is a laser beam printer using an electrophotographic process.

Reference numeral 102 denotes an engine section (hardware mechanism section) of the printer. 100 is a video controller unit,
The engine contra 105 of the engine unit 102 is controlled.

In the engine section 102, 112 is a rotary drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum).
It is.

The photosensitive drum 112 is rotationally driven in the clockwise direction indicated by the arrow at a predetermined peripheral speed (process speed), and the drum peripheral surface is covered by the primary charger 11 during the rotating process.
1 uniformly charges the particles to a predetermined polarity and potential.

The laser scanner unit 10 is provided on the charging surface.
6 to 109, laser scanning exposure 110 corresponding to the target image information is performed, and an electrostatic latent image corresponding to the target image information is formed on the peripheral surface of the photosensitive drum. In the laser scanner units 106 to 109, 106 is a laser driver,
107 is a laser diode, 108 is a polygon mirror,
Reference numeral 109 is a laser beam reflecting mirror.

The electrostatic latent image formed on the peripheral surface of the rotating photosensitive drum 112 is reversely developed as a toner image by the developing device 113.

On the other hand, one sheet of printing paper (transfer material) S as a recording medium is fed from the paper feed cassette 120 by the paper feed roller 121, and includes a conveyance roller, a registration roller, etc., which are not shown in the drawing. Photosensitive drum 1 through path P1
The toner image formed on the surface of the rotary photosensitive drum 112 is sequentially transferred to the surface of the recording medium S by being conveyed at a predetermined timing to the transfer portion T which is a pressure contact nip portion between the roller 12 and the transfer roller 114 brought into contact therewith. It will be (printed). A transfer device cleaner 128 removes stains from the peripheral surface of the transfer roller 114.

The recording medium P that has passed the transfer portion T is separated from the surface of the rotary photosensitive drum 112, is introduced into the image heating and fixing device 116 through the sheet path P2, and is subjected to the heating and fixing process of the transferred unfixed toner image. The sheet is received and is discharged as a print out of the printer through the sheet path P3. The image heating and fixing device 116 is a magnetic induction heating type heating device. This will be described in detail in section (2) below.

The surface of the rotating photosensitive drum 112 after the transfer of the toner image onto the recording medium S at the transfer portion T is cleaned by a cleaning device 115 to remove residual contaminants such as residual toner after transfer and is repeatedly used for image formation. To be done.

In the printer of this example, the photosensitive drum 1
A process cartridge PC is composed of four process devices including a primary charger 111, a developing device 113, and a cleaning device 115, which can be collectively attached to and detached from the printer body.

In the video controller section 100, 1
Reference numeral 03 is a video controller, 101 is a host I / F circuit, and 104 is a display / operation panel unit. The video controller section 100 will be described in detail in section (3) below.

(2) Image heating and fixing device 116 (FIGS. 2 to 5) FIG. 2 is an enlarged cross-sectional model diagram of a main part of the image heating and fixing device 116 as a magnetic induction heating type heating device in this embodiment. 3 is a structural model diagram of the fixing roller and a field coil drive circuit diagram.

The image heating and fixing device 116 in this embodiment.
Is a high-frequency magnetic field generating means 1101-1
Magnetic metal fixing roller 117 and pressure roller 1 as a heating body that is magnetically induction-heated to a predetermined fixing temperature by 104.
A pair of rotary rollers pressed against each other with 18 is a basic structure.

The pressure contact nip portion N between the rollers 117 and 118 is used as a heating position of the fixing nip portion, that is, the recording medium S which is a material to be heated, and the recording medium S on which the unfixed toner image t is carried. Is introduced and nipped and conveyed, the image is heated and fixed by the heat of the fixing roller 117 which is magnetically heated.

The fixing roller 117 has a cylindrical shape (cylindrical shape).
Magnetic magnetic roller, field coils 1101 to 1103 as magnetic field generating means provided therein, and an induction magnetic material (core material) 11 coupled to the main magnetic flux generated in the field coil.
It consists of 04.

The pressure roller 118 is a heat-resistant elastic roller such as a silicone rubber roller and is pressed against the fixing roller 117 with a predetermined pressing force to form a fixing nip portion N having a predetermined width as a heating medium heating position.

1030 is the field coils 1100 to 11
03 is a high frequency converter for supplying a high frequency current. The field coils 1100 to 1103 may have various configurations, but in this example, four sets of coils 1100 to 1103 are used.
Are connected in series.

With this configuration, the high frequency converter 1030
When a high frequency current is applied from the field coils 1100 to 1103, the field coils 1100 to 1103 give a high frequency magnetic field to the metal on the opposite surface, that is, the inner surface of the cylindrical magnetic metal roller which is the fixing roller 117, by the high frequency current. . When the high frequency magnetic field is applied to the cylindrical magnetic metal roller 117, its magnetic flux forms a loop loop starting from the central portion of the coil that gives the super magnetic force and returning to the central portion of the coil with the route of minimum magnetic resistance. To do. That is, a system is formed that follows a path that minimizes the space (μ0) and the nonmagnetic metal portion.

Therefore, in the inside of the field coils 1100 to 1103, a magnetic circuit, that is, a member having a high magnetic permeability (core material, induction magnetic material) so that the magnetic flux is efficiently coupled to and penetrates the cylindrical magnetic metal roller. ) 1104 forms a magnetic path.

FIG. 4 shows how the high frequency converter 1030 supplies the switching power to the model having such a configuration.

In FIG. 4, a commercial AC input from a line is rectified by a double-wave rectifier 1200, and a field coil 1100 is passed through a switching semiconductor (FET) 1201.
To 1103 of the switching semiconductor 1
High frequency switching is performed by 201. 12
Reference numeral 02 is a diode and 1205 is a control IC.

Further, since the fixing roller 117 is formed with the magnetic coupling as described above, it can be represented by the same equivalent circuit as the switching transformer of the power supply.

Thus, an eddy current is generated in the cylindrical magnetic metal roller which is the fixing roller 117 by magnetic induction, and heat (Joule heat) is generated by the electric resistance of the magnetic metal, so that the fixing roller 117 itself is a heating member. It becomes a fever state. Since the heating element is the fixing roller 117 itself, the heat transfer model from the heat source can be realized with an extremely monotonous structure, and a stable fixing temperature can be obtained.

FIGS. 5A and 5B are schematic configuration diagrams of a magnetic induction heating type heating device having another configuration.

In the case of (a), a heat resistant film 117A containing a magnetic metal layer between the pressure plate 1300 and the pressure roller 118 (cylindrical film, endless belt film, endless web film, etc.). To form a pressure contact nip portion N, and the film 117A is pressed against the pressure plate 1300.
And the slide conveyance in the direction of arrow a (rotation conveyance.
Rotation conveyance / running conveyance). Further, the high frequency magnetic field generating means 110 is provided on the side opposite to the film sliding surface side of the pressure plate 1300.
1, 1104 (field coil and induction magnetic core material) are arranged. The high frequency magnetic field of the high frequency magnetic field generation means 1101 and 1104 is applied to the heat resistant film 117 at the nip portion N.
By acting on the magnetic metal layer A, the magnetic metal layer is heated by magnetic induction. That is, the heat-resistant film 117A substantially functions as a heating body.

When the heat-resistant film 117A is conveyed a and the magnetic metal layer of the heat-resistant film 117A is heated in the nip portion N by the action of the high-frequency magnetic field of the high-frequency magnetic field generators 1101 and 1104, the heat-resistant film of the nip portion N is heated. When a recording medium S carrying an unfixed toner image t as a material to be heated is introduced between the heat-sensitive film 117A and the pressure roller 118, the recording medium S becomes the film 117A.
The image is heated and fixed by the heat of the magnetic metal layer of the film 117A in the process of being conveyed in the nip portion N together with the film 117A. The recording medium passing through the nip portion N is separated from the surface of the film 117A and conveyed.
The entire film 117A may be a magnetic metal film.

In the case of (b), the pressure plate 1300 is a magnetic metal member, and the heat resistant film 117B is an ordinary heat resistant film without a magnetic metal layer. In the case of this device, the pressure plate 1300, which is a magnetic metal member of the nip portion N, is formed by the action of the high frequency magnetic field of the high frequency magnetic field generating means 1101 and 1104.
Generates heat by magnetic induction and functions as a heating element. Nip part N
The recording medium S introduced into the pressurizing plate 1 is the pressure plate 1 as the heating body.
The heat of 300 is received through the film 117 to heat and fix the image. The recording medium passing through the nip portion N is separated from the surface of the film 117B and conveyed.

(3) Control System of Image Forming Apparatus (FIG. 6) FIG. 6 is a block diagram of an electric circuit of the image forming apparatus (printer) control system.

A power switch 1 is used to turn on / off the power of the image forming apparatus. Numeral 2 denotes a noise filter for reducing noise generated by the image forming apparatus so as not to propagate to the AC line. 3
Is a magnetic induction heating and fixing control unit, and is a fixing roller 117 which is heated by magnetic induction as a heating body of the magnetic induction heating and fixing device 116 (in the case of the apparatus of FIG. 5A, the heat resistant film 117A, ( In the case of the device of b), the pressure plate 13
00) temperature is detected by the temperature sensor 5, and the engine controller 105 is turned on so that the temperature becomes constant.
Used to perform / OFF control.

A low voltage power supply unit 4 generates a voltage necessary for operating the image forming apparatus.

Reference numeral 21 is a host I / F circuit, which is used to control the reception of code data from the host computer and input the code data to the video controller 103.

The video controller 103 includes the CPU 10
3a, RAM 103b, ROM 103c, buffer 10
3d, composed of a video I / F circuit 21, develops code data from a host computer into a dot image,
The dot image is stored in the buffer 103d and is transferred to the engine controller 105 through the video I / F circuit to control the display / input of the display / operation panel 104.

103f is a nonvolatile storage medium (NVRA
M, EEPROM, etc.) and stores initial information necessary for controlling the image forming apparatus. The power supply transmits various information set by the user using the display / operation panel 104 and information set by the control program of the image forming apparatus to the OF
It is for storing even after F, so that the setting state is restored at the time of restarting.

Reference numeral 102 denotes an engine unit, which is composed of elements necessary for the image forming apparatus to output an image on the recording medium S by the electrophotographic process.

Reference numeral 13 is a main motor, and the engine controller 105 outputs a signal from the main motor driver 14 to the O level.
N / OFF control is performed to control the photosensitive drum 112, the developing device 113,
The transfer roller 114, the transfer device cleaner 128, the fixing roller 117, the pressure roller 118, and the rollers such as the conveyance roller and the registration roller (not shown) in the sheet paths P1 to P3 are controlled to rotate, and the conveyance of the recording medium S is controlled. I do.

A scanner motor 11 reflects the laser light 110 generated by the laser diode 107 in the horizontal direction (main scanning direction) and hits the photosensitive drum 112 in the longitudinal direction to form a latent image. To rotate. The scanner motor driver 12 that controls the rotation of the polygon mirror 108 controls the rotation of the scanner motor 11 to be constant.

The video I / F circuit 2 converts the dot image created by the video controller 103 into a video signal.
1 is transferred to the engine controller 105 through
The laser driver 106 controls the laser diode 107 to adjust the intensity of the laser light 110 and perform modulation with a video signal.

The light receiving element 8 receives the laser beam reflected by the polygon mirror 108, converts it into an electric signal, and transmits it to the BD circuit 9. The BD circuit 9 shapes this signal and sends it to the video controller 103 as a horizontal synchronizing signal. Therefore, the light receiving element 8 is arranged in the horizontal direction (main scanning direction).
It is placed outside the photosensitive drum of and generates a signal for each horizontal scanning.

The temperature sensor 5 detects the temperature of the fixing roller 117, which serves as a heating body and is heated by magnetic induction, and outputs a signal to the engine controller 105. The engine controller 105 controls the magnetic induction heating fixing controller 3 based on this temperature signal.

The high-voltage power supply 10 transfers a primary charging voltage for primary charging the photosensitive drum 112, a developing voltage for developing the latent image formed on the photosensitive drum 112 with toner, and a transfer from the photosensitive drum 112 to the recording medium S. A transfer bias for separating the recording medium S from the photosensitive drum 112, a cleaning bias for separating unnecessary toner from the transfer roller 114, and the like. These voltages are applied to the primary charger 111, the developing device 113 (developing cylinder, etc.), the transfer roller 114, the transfer device cleaner 128, and the separator (not shown). The engine controller 105 controls the timing at which these voltages are generated.

The pickup solenoid 22 supplies the recording medium S one by one to feed the recording medium S one by one.
5 controls.

The fan motor 6 is used for the fixing device 11 after printing.
The fan motor driver 7 controls the rotation of the fan motor driver 7 by lowering the temperature of the heater 6 and controlling the temperature rise of each element forming the image forming apparatus.

The engine controller 105 is the CPU 1
05a, RAM105b, ROM105c, video I /
A series of control sequences configured by the F circuit 21 for feeding the recording medium S and performing print control using the electrophotographic process, communication control with the video controller, control of each component of the engine unit, electrophotographic process Performs sequence exception handling control.

Reference numerals 15, 16, 17, 18, 19, and 20 denote a paper size sensor, a paper presence sensor, a door sensor, a paper feed sensor, a paper discharge sensor, and a cartridge sensor, which are connected to the engine controller 105.

The video controller section 100 develops the code data from the host computer into bitmap information which is image information. The bitmap data is the image memory (buffer) 103f of the video controller 103.
Is stored once. The video controller 103 in which the image of one page is stored requests the engine unit 102 to prepare for image output.

The engine controller 105 starts control so that the printer is ready for printing, and activates each element constituting the engine section 102. The rotation control of the main motor 28 and the scanner motor 11 is started. The control is started so that the temperature of the fixing roller 117 becomes the fixable temperature. The laser light amount is controlled to control and adjust the laser driver 106 so as to obtain a predetermined light amount. Scanner motor 11
When the adjustment of the laser light amount is completed, the BD signal obtained by shaping the signal detected by the light receiving element 8 by the BD circuit 9 is monitored to determine that there is no abnormality. It is judged that there is no abnormality in the control of each of these elements, and the pickup solenoid 22 is turned on.
Then, the recording medium S is fed.

The timing at which the fed recording medium S passes the paper feed sensor 18 is detected, and the leading edge synchronizing signal (vertical synchronizing signal) of the recording medium and the horizontal synchronizing signal ( BD signal).

The video controller 103 uses the buffer 1
The dot image of 03f is sent to the engine unit 102 as a video signal for each row in the horizontal direction in synchronization with the synchronizing signals in the vertical and horizontal directions.

The engine controller 105 masks the video signal so that the laser diode 107 does not emit light except when the image forming area (image printable area) on the recording medium S and the timing at which the light receiving element 8 detects the laser light. . The masked video signal is the laser driver 106.
And modulating the laser light with the laser diode 107,
The laser light 110 is reflected by the polygon mirror 108 and exposes the photosensitive drum 112.

On the other hand, the engine controller 105 controls the high voltage power source 10 to generate the primary charging voltage VPr for primary charging the photosensitive drum 112 so that an image can be formed from the front end of the recording medium S. The photosensitive drum 112 is negatively charged by the primary charging voltage. At the same time, application of the transfer device cleaning bias VTc to the transfer device cleaner is started to start cleaning of the transfer device.

Next, the potential of the surface of the photosensitive drum 112 exposed with the laser beam 110 is neutralized (indicated by plus in the figure). A latent image is formed on the portion exposed by the laser beam, and the latent image is developed with toner. The developing voltage VDP is applied to the developing device 113 to negatively charge the toner. Since the dark portion of the photosensitive drum 112 has a negative potential and the bright portion is higher than this potential, the negatively charged toner develops the bright portion of the photosensitive drum 112.

The developed toner on the photosensitive drum 112 is transferred to the recording medium S. The transfer bias VTr is a positive voltage and attracts the negatively charged toner to the recording medium S. Since the transferred recording medium S is charged, it is discharged by the discharging needle. After the charge is removed, the recording medium S is guided to the fixing device 116 of the magnetic induction heating system to fix the image.

The video controller 103 expands the image information of the next page.

A command is issued to the engine unit 102 whose data has been expanded into a bitmap so as to re-feed it.

The bitmap data is output to the recording medium of the next page. The recording medium on which the image is fixed by the fixing device 116 is discharged by the sheet path P3.

An image is formed on the recording medium through such a process.

(4) Temperature Control Operation of Fixing Device 116 (FIGS. 7 to 9) This example is an example of the device configuration according to claims 1 to 8 of the claims, and a small size recording The fixing roller 117 of the fixing device 116 when the medium S is continuously fed.
This is to suppress the temperature rise of the non-sheet passing portion (hereinafter referred to as a heating element) and to secure good image fixability even when the apparatus is cold.

.. Example 1 In this example, the process speed of the printer of FIG. 1 is set to 24 so that the recording medium A4 size can output four sheets per minute.
mm / sec, the distance between sheets during continuous sheet feeding was 57 mm, and the interval was about 2.4 sec. At this time, as a method of changing the ratio of the non-heating time of the heating body (fixing roller) 117 of the fixing device 116 between the sheets, in this example, the number of continuously passed sheets, that is, the sheet passing time is stored in the CPU. .

Specifically, as shown in FIG. 6, the heat generation of the heating element 117 was turned off for 0.5 seconds until the first fifth sheet of paper was passed, and then the temperature was raised to 180 ° C. in 1.9 seconds. At this time, the heating element 117 (to be precise, the field coils 1100 to 1 for magnetically heating the fixing roller 117 as the heating element).
Power applied to 103) (more accurately, field coil 110 that magnetically heats fixing roller 117 as a heating body)
The electric power to be given to 0 to 1103, the same hereinafter) is measured by measuring the electric power necessary for controlling the temperature of the heating element 117 to 180 ° C. at the rear end portion of the sheet immediately before the sheet is passed, and adding the electric power again to 180 degrees. ℃
I tried to become.

In this state, unless the optimum electric power is input to maintain the temperature of the heating element 117 at 180 ° C.,
If the power is higher than this, the overshoot becomes large and a high temperature offset occurs. Below this, the heating element 117
This is because the image does not rise up to 180 ° C., resulting in a defective fixing image.

For the next 5 to 10 sheets, the heating element 117 is turned off for 1.2 seconds, and the heating element 117 is turned off for 1.2 seconds.
Was raised to 180 ° C. Also at this time, the electric power to be applied to the heating element 117 is the electric power required to control the temperature to 180 ° C. at the rear end of the sheet one sheet before the heating element 117.
Was heated to 180 ° C.

After the 10th sheet was passed, the power was turned off for 2.0 sec, and the heating element 117 was raised to 180 ° C. in 0.4 sec.

An envelope-sized paper (recording medium) was continuously fed while comparing with the conventional control by using such a control method. As in the conventional method, the heating element 117 is heated to 180 ° C
In the case where the temperature is controlled to, the surface temperature of the non-sheet passing portion area of the heating element 117 changes with time as shown in FIG.
The temperature of the 0th sheet reaches 250 ° C., and when A4 paper is passed in this state, a step due to the difference in thermal expansion occurs in the pressure roller portion corresponding to the boundary between the sheet passing portion area and the non-sheet passing portion area of the heating element 117. Paper wrinkles have occurred due to the occurrence of.

Although a silicone rubber roller having excellent heat resistance is used as the pressure roller 118, the temperature that can be continuously used is 230 ° C. or lower, and if this state is continued for a long time, the silicone rubber will be thermally deteriorated. Raised and damaged.

In the control method of this example, the temperature of the non-sheet passing portion area of the heating element 117 is as shown in FIG. 8 (the temperature during sheet feeding is plotted), and the heating element surface temperature is 210 ° C. even with the seventh sheet of sheet passing. Subsided This is because the non-heating state is provided as described above, and when parts such as the pressure roller are warmed up, the non-heating time is lengthened to cool the heating element 117 between the sheets as much as possible.

In other words, as in the present example, the second sheet after the 10th sheet is passed for 2 seconds.
When the non-heated state of ec is provided, the temperature of the non-sheet passing portion area of the heating element 117 has a temperature drop of about 20 to 30 deg on the surface during this, and the temperature rise and fall are repeated between the sheet passing and the sheet non-passing. As a result, the effect of suppressing the temperature rise of the non-sheet passing portion area of the heating element 117 is produced.

By doing so, the paper wrinkles and the heat deterioration of the pressure roller 118, which have occurred conventionally, are eliminated, and a new fixing system having excellent durability can be constructed.

In this example, the heating of the heating element 117 is turned on / off between the recording media, but the heating may be turned off at the rear end of the toner image area of the recording medium S, for example.
Needless to say, if the temperature of the heating element 117 rises quickly, heating may be performed from the front end of the recording medium S to the image area.

Further, when the heating rate of the heating element 117 is low and the heat radiation is fast, if the heat generation of the heating element 117 is stopped, the temperature drop becomes too large until the next recording medium S reaches the fixing nip portion N. In some cases, the heating element 117 cannot be heated to the fixing temperature. In such a case, the heating element 117
It is possible to use a method in which the heating voltage is not completely turned off, but the energization voltage is reduced or the duty of pulse energization is reduced to reduce the heat generation amount.

[0114] Example 2 In the above example, the number of sheets of the recording medium S passed is counted as information for changing the non-heating time of the heating element 117 between sheets, and switching is performed for each number of sheets. In this example, the recording medium S is fixed. Immediately after passing through the nip portion N, the heating element 11
The heat generation of No. 7 is stopped, the rate of decrease of the temperature of the surface of the heating element is detected, and the time to start the next heat generation of the heating element 117 is determined according to the speed.

In other words, if the descending speed is high, the pressure roller 118 of the apparatus is still cold and heat is likely to be dissipated. In this state, the heating of the heating element 117 is restarted quickly. On the other hand, in the case where the descending speed is slow, the heat is not easily transferred to other members and the device has already been heated. Therefore, in this state, the non-heating time of the heating element 117 is set to be as long as possible, and This is to prevent the temperature rise in the area.

As a concrete method, in this example, the controlled temperature is 1
Detect the time for the temperature of the heating element to fall from 80 ° C to 175 ° C. If this time is 100 msec or less, the non-heating time is 0.4 sec, 100-300 msec is the non-heating time 1.2 sec, and 300 msec or more is the non-heating time. 2se
It was divided into 3 parts. Next, the method of raising the heating element 117 to 180 ° C. is the same as in the above example.

By doing so, the temperature rise in the non-sheet passing portion area of the heating element 117 can be suppressed as shown in FIG. 8 as in the above example.

Further, in the above example, the number of sheets of the recording medium is uniquely changed, but in this example, since the change is reflected in consideration of the warming state of the apparatus, the control has higher environmental adaptability.

In the above, immediately after the recording medium S has passed through the fixing nip portion N, the power supply to the heating body 117 is reduced and the warming condition of the apparatus is measured. However, conversely, it is possible to measure the degree of warming of the apparatus by heating for a fixed time, for example, about 0.3 sec and measuring the temperature rising rate.
Alternatively, the non-heating time between the sheets may be changed by determining the warming condition of the apparatus based on the temperature rising rate from the non-heating time between the previous sheets.

Further, since the calorific value is insufficient in the initial stage of continuous printing, the sheet interval is determined by the temperature rising rate while heating the heating element 117 between sheets, and the sheet is cooled in the non-energized or low power state from the middle. However, it is also possible to combine them so that the interval between sheets is determined by the temperature decrease rate.

. Example 3 This example was carried out by detecting the electric power required to maintain the heating element 117 at 180 ° C. as information for changing the non-heating time of the heating element 117 when the sheet is not passed.

This is similar to the above example and the heating element 11
In order to maintain the temperature of 7 at 180 ° C., the pressure roller material 118
If they are cold, the heat taken up by them is large, so about 2
Power of about 00W is required. However, when the paper is continuously fed and the pressure roller and the like are warmed up, the amount of heat taken by these is reduced, and in order to maintain the temperature of the heating body at 180 ° C., an electric power of about 100 W is sufficient.

In this example, paying attention to this fact, 18
A means for detecting electric power required to maintain the temperature of the heating body at 0 ° C. was provided, and the non-heating time between paper sheets, which is the next non-paper feeding time, was determined according to the input power during paper feeding.

Specifically, when 180 W or more is required to maintain the heating body temperature at 180 ° C., the non-heating time is 0.4
sec, 180-130W, the non-heating time is 1.2
sec, 2 sec when 130 W or less. Next, the method for raising the heating element 117 to 180 ° C. is the same as in the above example.

By doing so, the temperature rise of the heating element 117 could be suppressed to about 210 ° C. even when seven envelopes were continuously fed, as in the above example.

.. Example 4 In the above examples 1 to 4, the non-heating time of the heating body 117 when the paper is not passed is changed irrespective of the size of the recording medium S, but this may be limited to the small size paper. For example, in the laser beam printer used in the description of the present embodiment, the maximum paper passing size of the recording medium S is the LTR size, and therefore the above examples are limited to those smaller than this size, such as B5 paper and envelopes. Apply. As a method for detecting the paper size, a. In case of cassette feeding, the paper size signal from the cassette is detected and performed. B. It is possible to provide a sensor in the paper feeding section, detect the length of the paper by this sensor, and predict the paper size based on this information. However, any method may be used if the paper size is known.

When it is determined that the small-size paper is continuously fed in this way, for example, the space between the sheets is set to 2 se from the letter size.
c The length is set to 2 to 4 seconds for the letter size paper and 4.4 seconds for the small size paper.
It is possible to change the non-heating time of 17. This makes it possible to lengthen the cooling time of the heating element 117 between the sheets of small size paper, and further reduce the temperature rise in the non-sheet passing portion.

By doing so, the throughput does not drop when the maximum paper size is passed, and the throughput drops only when the small size paper is passed, but the temperature rise of the non-paper-passing portion can be further prevented. it can.

In this example, as described above, the small size of the recording medium S is detected by the sensor provided at the paper feeding position, and when the small size paper is passed, the distance between the papers is about 106 m.
The non-heating time was changed to m and 4.4 sec. Specifically, the energization was turned off for 1 to 5 sheets of paper for 1.0 sec, and the heating element 117 was raised to 180 ° C. for the remaining 3.4 sec. 1.7 sec off for 5 to 10 sheets of paper passed.
7 sec on, 3.8 sec off after 10 sheets,
The heating of the heating element 117 was controlled by turning on for 0.6 sec.

In this way, the temperature rise of the non-sheet passing portion of the heating element 117 is further suppressed, and after passing 70 sheets, the temperature of the heating element surface is lowered by 10 deg more than in the above examples, and more stable sheet feeding is possible. Became.

As the information for changing the non-heating time of the heating element 117 between the sheets, the same result can be obtained by detecting the descending speed when the energization is off and the electric power for maintaining 180 ° C. as in the above example. The effect is obtained.

As in the above examples (1) to (5), when small size paper such as B5 paper or envelope is continuously passed as the recording medium,
By controlling the non-heating state of the heating element 117 between the sheets and changing the non-heating time depending on the state of the apparatus, the temperature rise in the non-sheet passing portion area of the heating element 117 at the time of passing small size paper is suppressed. Therefore, it is possible to eliminate the adverse effect of the excessive temperature rise in the non-sheet passing portion area of the heating element 117.

<Second Embodiment> (FIGS. 10 to 19) This embodiment is an example of the device configuration according to claims 9 and 10 of the claims, and is useful for changing the temperature of the heating element 117. This eliminates erroneous detection of control, and makes it possible to keep the temperature of the heating body constant regardless of the mode in which the device is used, preventing defective fixing and high-temperature offset.

.. Example 1 In this example, first, when the temperature of the heating element 117 is raised,
The heating body 117 is started up by a constant power of 500W. This is because the power is controlled to be constant power by the power control means by pulse width modulation such as phase control and wave number control based on information from an AC voltage detection circuit (not shown).

In this example, the fundamental wave number for wave number control was 20 waves at f to 50 Hz and V _{ac to} 100 V, and the heating element 117 was started up under the conditions of 14 waves-ON and 6 waves-OFF. This time,
If the entire apparatus is cold, the rising speed of the heating element 117 will be slow, and conversely, if the entire apparatus such as the pressure roller 118 is warm, the rising speed will be fast. Therefore, by detecting this speed, the state of the apparatus can be estimated, and by setting the set temperature of the heating body 117 for the first sheet of paper passing in accordance with these, the temperature of the heating body of the first sheet of paper passing can be determined to be due to poor fixing and high It can be set in the area without offset.

Next, the case where the recording medium S is continuously placed will be described. This sets the temperature of the heating element 117 according to an algorithm as shown in FIG. That is, a. The heating element 117 is forcibly turned off for 0.6 sec at the same time when the recording medium S leaves the fixing nip portion N. b. Next, when the heating element 117 is turned off, 0 to 0.5
Measure how much the temperature of the heating element falls in sec. c. From this measurement, the temperature control temperature of the heating element 117 at the time of the next sheet passing is determined according to Table 1.

[0137]

[Table 1] d. The temperature control of the heating element 117 for the next recording medium S is started.

This is because the descending speed is detected during the heating body OFF time, and it is erroneously detected if the two are kept the same as in the conventional case, and as shown in FIG. 11, the heating body temperature is still 210 °.
C It was necessary to switch to 200 ° C, and a defective fixing image was sometimes ejected. However, as shown in Fig. 12, the temperature of the surface of the heating element can be reliably measured according to Table 1 without erroneous detection. Will be set.

By doing so, the temperature lowering speed of the heating element 117 can be reliably detected, and the state of the entire apparatus such as the pressure roller 118 can be estimated from these information,
Fig. 13 shows the heating element temperature by changing the heating element setting temperature.
As described above, it is possible to prevent the fixing failure and the high temperature offset.

.. Example 2 In the above example, the temperature lowering speed of the heating element 117 is detected, but the same effect can be obtained by changing the heating element temperature control temperature according to the reached temperature of the heating element 117 after a certain time as in this example.

Specifically, the heating body temperature is set by the algorithm shown in FIG.

A. The heating element 117 is turned off for 1.7 seconds at the same time when the recording medium S leaves the fixing nip portion N. b. Next, measure the temperature reached by the heating element 117 after 1.5 seconds c. From this value, the heating temperature control temperature at the time of the next paper passing is shown in Table 2.
To decide according to

[0143]

[Table 2] d. The temperature control of the heating element 117 for the next recording medium S is started.

By doing so, the heating element temperature can be controlled without erroneous detection as in the above example, and as a result, the heating element temperature becomes constant, and high temperature offset and fixing failure can be prevented. it can.

.. Example 3 In the above example, the energization of the heating element 117 was stopped, and at the same time, the temperature lowering rate was started to be detected. is there. That is, the temperature control temperature of the next heating element 117 is determined by the algorithm as shown in FIG.

A. The heating element 117 is forcibly turned off for 0.7 sec when the recording medium S passes through the fixing nip portion N. b. Next, 0.1 to 0.1 while the heating element 117 is turned off.
Measure how much the temperature of the heating element drops in 0.6 sec. C. From this measured value, the temperature control temperature of the surface of the heating element at the time of the next sheet passing is determined according to Table 3.

[0147]

[Table 3] d. The temperature control of the heating element 117 is started.

This is to eliminate the post-detection at the start of measurement as shown in FIG. 16 in observing the temperature lowering speed of the heating element 117.

By doing so, as shown in FIG. 17, even if the temperature lowering speed of the heating element 117 varies in the conveying speed of the recording medium S and the timing when the trailing edge passes through the fixing nip portion N varies, accurate measurement can be performed. A good fixed image can be obtained by changing the next heating member set temperature based on these information.

. Example 4 In this example, a method will be described in which a temperature control mode is provided between the sheets and the temperature is lowered to a predetermined 0.5 sec time.

This is because the temperature is detected and judged only by the temperature even though the temperature control mode between the sheets has been entered by 0.5 sec as described above. For this reason, it is determined that the device is warming up when the temperature is higher than the temperature control temperature after 0.5 sec, and the heating element 11
The controlled temperature of 7 is lowered.

In this example, in order to eliminate such erroneous detection, the temperature control temperature of the heating element 117 is determined by an algorithm as shown in FIG.

A. When the recording medium S passes through the fixing nip portion N, the heating element 117 is forcibly turned off for 1.7 seconds. B. Measure the temperature reached 1.5 seconds after the heating element 117 is turned off. C. Based on this measurement value, the next controlled temperature is determined according to Table 4.

[0154]

[Table 4] d. When the paper interval is long, the paper interval temperature control mode is provided at a position 15 deg lower than this temperature control temperature. E. When the recording medium S arrives at the fixing nip portion N, the temperature control mode at the time of passing the paper is entered.

By doing so, the temperature of the surface of the heating element becomes as shown in FIG. 19, and even if the second temperature adjustment mode is provided between the sheets, the surface temperature adjustment temperature of the heating element 117 does not erroneously detect. Can be changed.

.. Example 5 In the above-mentioned examples (1) to (5), the heating element 117 was forcibly turned off between the sheets and the temperature drop was observed. Even by observing the temperature rise of the heating element 117 in a short time, the state of the apparatus can be understood and the temperature control temperature of the heating element 117 at the time of the next sheet passing can be reliably determined.

As in the above examples (1) to (7), the heating element 117 is
By supplying a certain amount of power to the device or forcibly stopping the energization for a longer time than when the temperature change of the heating body 117 is observed, erroneous detection for changing the temperature of the heating body 117 is eliminated. The effect is that you can.

<Third Embodiment> (FIGS. 20 to 23) This embodiment is an example of the device configuration according to claims 11 and 12 of the claims, and is the same as the second embodiment. Similarly, the erroneous detection of the control for the temperature change of the heating element 117 can be eliminated, the heating element temperature can be kept constant regardless of the mode in which the apparatus is used, and fixing failure and high temperature offset are prevented.

[0159] Example 1 Similar to the example of the second embodiment, the heating element 117 is 5
It is started by a constant power of 00W. In this example, f to 5
The heating element 11 has a fundamental wave number of 20 waves at a frequency control of 0 Hz and V _{ac to} 100 V, and 14 waves-ON and 6 waves-OFF.
The temperature of 7 was raised.

At this time, if the entire apparatus is cold, the heating element 1
The ascending speed of 17 becomes gentle, and conversely, the pressure roller 11
If the entire device such as 8 is warm, the rising speed becomes faster. Therefore, the state of the apparatus can be estimated by detecting this speed, and the temperature of the heating body 117 for the first sheet of paper passing can be determined by determining the set temperature of the heating body for the first sheet of paper passing according to these conditions. As in the second embodiment, the area can be set in the area where there is no.

Next, the case where the recording medium S is continuously placed will be described. This sets the heating body temperature by an algorithm as shown in FIG.

In a step, the heating element 117 switches from the control temperature T ₁ to T'at the same time when the recording medium S leaves the fixing nip portion N.

The timer is started in step.

In the step, the temperature T of the heating element 117 becomes T '.
If it is higher, go to step NO.

If the timer does not reach the sampling time in step, the process returns to step.

If YES in the step, Flag is set in the step.

Then, in step, the temperature control between the sheets is started and T '
To control.

If the timer exceeds the sampling time in the step, the flag is not set and the heating element 117 is controlled by T ′ without setting the flag.

For the next recording medium S, if Flag is set in the step, the heating element 117 is controlled at the same temperature T ₁ as the recording medium S before the step.

If the Flag is not raised in the step, the control temperature is changed to T ₂ in the step and the next recording medium S is changed.
To fix.

Heating body 11 when controlled in this way
The temperature change of No. 7 is shown in FIG.

In this way, when the Flag is set as a guide, it is determined that the apparatus is cold, and the control temperature during sheet feeding is not changed. When there is no Flag, the control temperature is lowered to lower the temperature of the heating element 117. Can be controlled within a temperature range where neither fixing failure nor high-temperature offset occurs.

(Experimental Example) As shown in Table 5 below, the control temperature of the heating element 117 during sheet feeding was sequentially switched. That is, Fla
When g did not rise, the control temperature of the heating element 117 during paper passing was changed to 180 ° C. → 170 ° C., 170 ° C. → 163 ° C., 163 ° C. → 155. The sampling time was t _{0 =} 0.3 sec.

[0174]

[Table 5] As a result, as shown in FIG. 22, the temperature of the heating element 117 could be controlled within a range in which neither high temperature offset nor fixing failure occurred.

[0175]. Example 2 In the above example, the following control temperature was determined using the flag as a guide. In this example, it is determined whether or not the timing of adjusting the sheet temperature is early. That is, the time t from the time when the control temperature between the sheets is reached to a predetermined time t ₀ ′ (this time may be a fixed time after the control of the paper interval is started) is measured.

This time t is short when the pressure roller 118 and the like are warm and long when it is cold.

Therefore, when this time t is short as t ₁ as shown in FIG. 23A, the heating body control temperature for the next recording medium S is lowered to T ₂ . On the other hand, when t is as long as t ₂ as in (b), the heating body control temperature for the next recording medium S remains T ₁ .

The heating body control temperature during the sheet passing and between the sheets is the same as that of the embodiment, and when t ₀ ′ is 0.3 sec, t ≦
In 0.2 sec, the heating body control temperature for the next recording medium is the same as the heating body control temperature for the previous recording medium, and when 0.3 ≧ t> 0.2 sec, the heating medium control temperature is changed to the next recording medium. By lowering the heating body control temperature by one step (that is, when the temperature of the previous recording medium is controlled to 180 ° C., the temperature is lowered to 170 ° C. of the next recording medium), the temperature shown in FIG.
The same result was obtained.

As in the above example, it is possible to obtain the quick-start fixing device 116 in which neither high temperature offset nor defective fixing occurs.

<Fourth Embodiment> (FIGS. 24 to 27) This embodiment is an example of the apparatus configuration according to claims 13 to 15 of the claims, and is the same as the second embodiment. The temperature of the heating element 117 can be kept constant no matter what mode the device is used, by eliminating erroneous detection of control with respect to the temperature change of the heating element 117, and preventing fixing failure and high temperature offset. is there.

[0181] Example 1 FIG. 24 shows the heating element temperature during continuous printing in this example,
It is a time change figure of a pressure roller temperature.

First, when the heating element 117 is started up, the heating element temperature is set according to the algorithm of FIG. 25 and Table 6.

[0183]

[Table 6] The heating element 117 is started up by energizing 700 W constant power. When the temperature of the heating element 117 reaches 165 ° C, the energizing power is changed to 500W.

That is, based on information such as the detection of the AC power supply voltage, the power control means by pulse width modulation such as phase control and wave number control supplies power so that constant power is obtained. In this example, AC voltage 100% of f to 50 Hz and V _{ac to} 100 V
AC voltage 100msec-
ON and 40 msec-OFF were repeated and a constant power of 500 W was applied.

At this time, if the entire apparatus is cold, the heating element 1
The ascending rate of 17 becomes gentle, and conversely, the ascending speed becomes faster if the entire apparatus is warm. Therefore, the temperature of the pressure roller can be estimated by observing the rising speed of the heating element 117. By changing the set temperature of the heating element for the first sheet of the recording medium, the temperature of the pressure roller can be changed. Even if it is distorted, it is possible to prevent the fixing failure and the high temperature offset by keeping the heating member temperature constant by a simple operation.

In the paper passing state, for example, 200
If the temperature is controlled to ° C, the temperature ripple is controlled to be small by alternately switching the slightly higher power and the slightly lower power required.

For example, if the electric power required to maintain 200 ° C. is 180 W, then High-190 W and Low-1
Control to switch 70 W appropriately.

This is because it is difficult to accurately match the required power for both phase control and wave number control, and variations in the heat capacity of the device and how it warms up are as described above.
This is because it is better to switch and control at two levels of w.

In the space between sheets, the high level is set to 190 W and the low level is greatly reduced, for example, 0 W.

Then, a large temperature ripple is generated as shown in FIG. This temperature ripple becomes large as shown in (a) because the heat of the heating body 117 is rapidly transmitted to the pressure roller 118 and the like when the apparatus is cold. On the other hand, the ripple after printing about 50 sheets of paper continuously is small as shown in (b) because the apparatus is warm.

Therefore, by measuring the magnitude of this ripple T _p -T _b , it is possible to judge the degree of warming of the pressure roller. Therefore, based on this T _p -T _b , the control temperature at the time of sheet feeding is controlled. It is possible to continue printing without any offset or fixing failure by switching the above.

In FIG. 24, the control temperature is switched according to the magnitude of ripple according to Table 7.

[0193]

[Table 7] In this way, the heating element temperature is controlled based on the degree of warming of the apparatus, and is gradually lowered during continuous printing, whereby fixing failure and offset can be prevented.

The control of High and Low between the sheets may be performed not in the entire sheet interval but in a part thereof, and an appropriate control temperature can be reached before the next recording medium S enters the fixing nip portion N. The control may be switched to the control when the recording medium is present at the timing.

[0195] Example 2 Although the above example was controlled based on T _p -T _b, it may be controlled based on T _b or T _p.

When Table 8 was used as the control at T _b and Table 9 was used as the control at T _p , in both cases, it was possible to continue the continuous printing without the occurrence of the fixing failure in the offset.

[0197]

[Table 8]

[0198]

[Table 9] . Example 3 In the above-mentioned example, the heating element 1 is used at the same temperature between sheets as during sheet passing.
However, in this example, the heating body control temperature between the sheets is also lowered by 15 deg or more than that during sheet feeding.

As a result, the temperature rise of the apparatus during continuous printing is suppressed, and the heating element 1 for continuous printing of small size paper
It is possible to reduce the temperature rise in the non-sheet passing portion area 17 and to prevent unnecessary power consumption.

Further, it is possible to increase the ripple and the like, and thereby it is possible to improve the detection accuracy.
This ripple comparison is shown in FIG. (A) is the case of the above example, and (b) is the case of this example. T is a control temperature during sheet passing, and T'is a control temperature between sheets.

As in the above examples, the temperature ripple is generated by controlling the electric power supplied to the heating element 117 between the paper and the High level and the greatly reduced Low, and the next recording is performed with the magnitude of this ripple. The heating element control temperature for the medium S is switched to enable continuous printing without causing an offset and a fixing failure.

<Fifth Embodiment> (FIGS. 28 to 35) In this embodiment, when the heating element 117 is raised to a predetermined temperature by the electric energy controlled by the wave number control, its temperature rising rate is detected. In a heating device that determines various control values thereafter according to the speed, an error at the time of detecting the speed is reduced and the control after rising is performed more accurately.

[0203] Example 1 In this example, a laser beam printer as an image forming apparatus has a recording medium feeding speed (process speed) 56.
The printer outputs 6 sheets of A4 size paper per minute at mm / sec.

The heating element 117 is started up with a constant power of 500W. At this time, wave number control is applied to the energization of the heating element 117 based on information from an AC voltage detection circuit (not shown) so that the power supplied to the heating element 117 will be 500 W regardless of how many volts the input voltage is. ing.

In this example, f to 50 Hz, V _{ac to} 115 V
The basic wave number of the wave number control was set to 20 waves with the AC voltage of 10 and the heating element 117 was started under the conditions of 10 waves-ON and 10 waves-OFF.

Therefore, the time t _W required for the fundamental wave number to repeat one cycle is t _W = 1.0 (sec) × [20 (wave) ÷ {50 (Hz) × 2}] = 0.2 (sec ) = 200 (msec).

Here, the reason why it becomes 50 (Hz) × 2 is that the AC half wave is counted as one wave in the wave number control of this example. That is, there are 100 waves per second.

By the wave number control, the temperature of the heating element 117 continues to rise while drawing a minute temperature ripple, and when the thermistor detection temperature reaches 120 ° C, the CPU raises the temperature for a certain time t _base from that point. Detect speed.

[0209] More specifically, the heating element 117 is 120 °.
When the temperature reaches C, the CPU starts a timer and measures how many degrees the temperature has risen after a certain time t _base .

That is, the temperature rising rate here is t _base
An average heating rate of between a temperature between t _base is Tde
When the temperature rises by g, the heating rate v becomes v = dT / d (t _base ).

At this time, if the entire apparatus is cold, the heating element 1
The rate of temperature rise of 17 becomes gentle, and conversely becomes faster if it is warm. Therefore, the temperature of the pressure roller or the like can be estimated by looking at the temperature increase rate v, and the control values of the heating body temperature control temperature of the first sheet of the recording medium and the power supply and the like are determined according to them.
In this example, the temperature control temperature is determined by the control table shown in Table 10.

[0212]

[Table 10] Under the conditions of this example, the temperature of the heating element 117 is 100 ° C to 16 ° C.
Between 0 ° C, the heating rate of the heating element 117 is O in the fundamental wave number.
The present inventors confirmed that it was about 150 deg / sec at N hours. It should be noted that this is the maximum value of the heating body temperature raising rate in the apparatus of this example.

FIG. 28 shows wave number ripples when the temperature of the heating element 117 of the apparatus of this example rises. The average rate of temperature rise of the heating element 117 in units of the fundamental wave number is represented by the slope ξ of the line Q.

This speed coincides with the temperature rising speed detected when the heating element 117 of this example is started up at full energization without inputting wave number control at 500 W input.

That is, the constant power control using the wave number control also has the meaning of always trying to obtain the average rising rate of ξ under the condition that the temperature rise is ξ.

Therefore, the output value detected when the temperature increase rate is detected must be one that draws a line with a slope ξ, or one that is higher than that.

In this example, the temperature increase rate measurement time t
_{The base is set} to 200 nsec and is equal to the time t _W required for one cycle of the fundamental wave number. That is, t _base = t _w .

FIG. 29 shows the timing of temperature rise rate detection when this embodiment is applied. The temperature at which the heating element 117 rises in one cycle t _w of the fundamental wave number is always constant regardless of the timing of the fundamental wave number.

Therefore, if the measurement time t _base of the heating rate is made equal to one cycle t _w of the fundamental wave number, the measurement starts (12
Counting from 0 ° C), always for one cycle of the basic wave number is performed the measurement of the temperature at the stage of completion, t heating rate in the _{base v = dT / d (t} base) course of the Figure 28 tilt It will have the same value as ξ.

That is, no matter what position in the fundamental wave number the measurement is started, the error (dispersion of the measured value), which has been a problem in the past, does not occur at all.

In this example, the case in which the fundamental wave number is 20 waves is described, but it goes without saying that the value of the time t _base is changed if the fundamental wave number is changed. For example, in 10 wave-wave number control, 100 msec, In 15-wave number control, it is 150 msec.

Further, in the basic wave number, the wave number for turning on the heating element 117 is not limited to 10 waves, and can be changed from 0 wave to 20 waves by 20 wave control.

Of course, the constant power control value is variable depending on the device and is not limited to 500 W in this example.

The same applies to the following examples.

As described above, by making the temperature rising rate measurement time equal to the time required for one cycle of the fundamental wave number, the temperature rising rate can be accurately increased no matter where the measurement of the temperature rising rate is started. Can detect speed.

[0226]. Example 2 In the above example, the measurement time t _base of the heating rate is set to the same time as one cycle t _w of the fundamental wave number, but the measurement time t _base may be an integral multiple of the fundamental wave number cycle t _w . That is, t _base = nt _w (n = 1, 2, 3, ...) May be used.

As described above, the temperature rise in the fundamental wave number cycle does not change from any timing. This is the same no matter how many times the fundamental wave number is output. Therefore, even if the temperature rise is measured for a time of an integral multiple of the fundamental wave number period, the temperature rise can be detected without variation as in the above example. That is, an accurate temperature rising rate can be obtained.

For example, in the case of 20-wave control, the equal magnification is 200 m
sec, 2 times 400 msec, 3 times 600 msec
It becomes ‥‥.

FIG. 30 shows this, and it can be seen that all the temperature rising straight lines have the same slope if they are integral multiples.

Therefore, as shown in the above example, the variation of the detection speed is zero at the same magnification of the fundamental wave number cycle. Therefore, if the measurement time is an integral multiple of the fundamental wave number cycle, the variation is likewise zero. .

As described above, when the measurement time is doubled or tripled, even a minute timing shift when the CPU measures can be absorbed within the measurement time. The temperature rising rate can be detected more accurately.

The temperature sensor 5 (FIG. 6, thermistor)
If an A / D converter with a low bit number is used for A / D conversion of the output of, the temperature resolution that can be detected by the CPU will be low, and it will not be possible to detect the temperature accurately, but the measurement time Is taken longer, the low resolution of the A / D converter can be absorbed.

.. Example 3 In the above example, the measurement time of the heating rate is defined as t _base = nt _w (n = 1,2,3 ...) That is an integral multiple of the fundamental wave number period, but t _base is an integer of t _w It may be twice as close.

FIG. 31 shows two temperature rise curves on one graph for two types of measurement timings.

Normally, when the temperature rising rate is measured over time, the variation in the detected value (difference between the maximum detectable value and the minimum detectable value) is minimum at the position K where the measurement time is an integral multiple.
It becomes zero, and then increases again as the time increases, and becomes maximum at the position J where ON / OFF is switched in the fundamental wave number of the ascending curve a.

Ideally, the measurement is most accurate at the position K (FIG. 31) as in the above example, but even in the vicinity of the position K, variations in the measured values are a practical problem. Fits in the range without.

More specifically, in the case of the control table of Table 10, the measurement time can be set to the range of an integral multiple of the fundamental wave number period plus 10% of the fundamental wave number period and minus 10% of the fundamental wave number period. is there.

In this case, the control value may be shifted up or down by one on the table due to the variation in the measured value. However, in reality, it is ideal because of the performance of the A / D converter that was touched before. Even if the measurement is performed at the position, variations may occur, and one shift like this does not pose a problem in practical use.

Therefore, if the measurement time and the control table are decided so that the control values do not shift up and down by two or more on the table, and there is no practical problem with the control table, the measurement time is an integer of the fundamental wave number. It may be in the vicinity thereof instead of double.

[0240] Example 4 It was mentioned earlier that the longer the measurement time, the more the variation in the measurement value can be absorbed. However, this is not only the case when the measurement time is an integer multiple of the fundamental wave number period, but rather when the measurement time is a non-integer multiple. The effect is greater.

Therefore, when the measurement time is set to be long to some extent, the measurement time settable range (that is,
As in the example of (1), the range in which the control value shifts only one on the table) can be made wider.

FIG. 32 shows the settable range of the measurement time which is the allowable range when the table of Table 10 is used for the two types of measurement timings of FIG. In FIG. 32, the shaded area is a non-settable area.

That is, the straight line O in the figure shows 60 deg / sec with respect to the straight line Q having an average heating rate of 70 deg / sec, and the intersection of this straight line O and the two kinds of heating body temperature rise curves is shown in the figure. The area surrounded by the straight line drawn at right angles to the time axis and the heating temperature rise curve is the range where the variation in the detected value is 10 deg / sec or more, and it is not possible to set the measurement time in this range. Appropriate.

Therefore, the measurement time may be set in any manner other than the shaded area. That is, if the measurement time is set within this range, even if the average temperature rise rate may shift by one level on the table, it does not shift by two levels or more, and the control temperature can be limited to a shift of 4 deg or less.

Further, FIG. 33 shows the variation of the detection speed depending on the measurement time. As the measurement time becomes longer, the detection speed at the variation maximum position J approaches the average temperature increase rate ξ. . This is the reason why the settable range expands as the measurement time increases.

[0246] Further, although a natural consequence from the above, if the intersection of the no longer exists any more measurement time than in FIG. 32, the measured time t _base is very any value without regard to the basic wave number cycle Good.

In the case of the table of Table 10, the above condition is satisfied from the position P of FIG. As can be seen from the above, in this example, the settable range of the measurement time is determined by the table.

That is, the control may be roughly rough to a certain extent,
If the number of table switching steps is small, the measurement time may be short.

More specifically, in the table of Table 10, the variation of the detected value is allowed up to 10 deg / sec,
In the table as shown in Table 11, the deviation is up to 20 deg / sec and the settable range is wide.

If the control value correction mechanism is provided for the shift of the control value before the temperature control temperature is reached or even after the temperature control temperature is reached, the measurement time can be set. It is also possible to take a wider range.

[0251]

[Table 11] . Example 5 In the above-mentioned examples, the timing of measuring the temperature rising rate is simply defined by the measurement time, but it may be defined by the temperature range in which the measurement is performed. In this case, the temperature range may be set so that the required short passage time during heating of the heating body in the temperature range in which the measurement is performed is equal to or longer than the measurement time within which the variation in the measurement value falls within the allowable range.

That is, the temperature range may be wide in an apparatus having a high maximum temperature rising rate, and may be narrow in a system having a low maximum temperature rising rate.

At this time, this temperature range is defined as T _{base
Assuming that the} time required for passing between bases is t, the heating rate v can be expressed by v = d (T _base ) / dt.

In this example, the heat fixing device and the control table having the same basic structure as the above examples are used, and the measurement temperature range is set to 100 ° C to 160 ° C. FIG. 34 shows the timing of measurement in this example.

When the heating element 117 is energized and the heating element temperature rises, the heating rate is detected when the heating element temperature sensor 5 (FIG. 6) detects the heating element temperature between 100 ° C and 160 ° C. To be done.

More specifically, the heating element detection temperature is 100
The time from when the temperature reaches ° C to when 160 ° C is detected is measured.

The conditions here are the same as in the above example, but unlike the case where the measurement timing is defined by the measurement time, when it is defined by the temperature range, the minimum required time for measurement is slightly longer. . FIG. 35 shows this.

When the timing of measurement is specified in the temperature range as shown in FIG. 35, the measurement time is determined by the time from the last detection of the measurement start temperature to the first detection of the measurement end temperature. At this time, the heating element O in the fundamental wave number
It is obvious that the measurement end point is never reached at FF.

Therefore, in the above example, the minimum required time was 716 msec when the heating element was off,
When measuring in the temperature range as in this example, 716 mse is obtained by controlling 10 waves-ON and 10 waves-OFF by controlling 20 waves.
800 msec, which is an integer multiple of the fundamental wave number period exceeding c
Is the minimum time required.

In this example, the required transit time between 100 ° C. and 160 ° C. is 830 msec, and four fundamental wave numbers are included. That is, this required transit time exceeds the minimum required measurement time of 800 msec, and the variation in the measured values falls within the allowable range.

As described above, the variation can be suppressed within the allowable range by setting the measurement temperature range so that the minimum necessary measurement time can be obtained at any time.

As in the above examples, when the heating element is raised to the predetermined temperature with the electric power controlled by the wave number control, the heating rate is detected, and various control values thereafter are detected according to the rate. In the heating device that determines, by setting the temperature rise speed detection time at least equal to the time required for one cycle of the fundamental wave number of the wave number control, the error in speed detection is reduced and the control after rising is performed. You can do it more accurately.

<Others> In each of the above embodiments, the magnetic induction heating type heating device used as the image heating and fixing device 116 is a roller pair type (FIGS. 2 to 4). It goes without saying that the present invention can be applied to a magnetic induction heating type heating device having the configuration as shown in FIG.

The magnetic induction heating type heating apparatus of the present invention is
Not only as an image heating and fixing device, but also for example, a device that heats a recording medium carrying an image to modify the surface properties (such as polishing), a hypothetical fixing device, and heating, drying, and laminating while conveying sheet-like materials. It can be widely used as a heating device for materials to be heated such as a processing device.

[0265]

As described above, according to the present invention, in the heating device of the magnetic induction heating system, it is possible to suppress the temperature rise phenomenon in the non-sheet passing portion, improve the durability and reliability of the device, and save power. , The heating performance (fixing performance) can be improved, and the temperature control accuracy can be improved.

Therefore, for example, in the image heating and fixing device of the magnetic induction heating system, the excessive temperature rise phenomenon in the non-sheet passing portion area of the magnetic metal member as a heating body during continuous sheet passing of a small-sized recording medium. In addition, the temperature of the magnetic metal member can be kept constant regardless of the mode in which the device is used by eliminating erroneous detection of control when the temperature of the magnetic metal member is changed. Can be prevented and good image fixability can be secured. Therefore, it is possible to reduce the power consumption of the device, prolong its life, and improve its reliability.

Further, when the magnetic metal member as the heating body is raised to a predetermined temperature with the electric power controlled by the wave number control, its temperature rising rate is detected, and the error at the time of detecting the speed is reduced to rise. The later control can be performed more accurately.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus.

FIG. 2 is a schematic cross-sectional view of a roller pair type magnetic induction heating type image heating fixing device.

FIG. 3 is a structural explanatory view of a magnetic induction heating fixing roller (heating body).

FIG. 4 Field coil drive circuit diagram

5A and 5B are schematic configuration diagrams of a magnetic induction heating type heating device having another configuration.

FIG. 6 is a block diagram of an electric circuit of an image forming apparatus control system.

FIG. 7 is a schematic graph of a method of energizing a field coil.

FIG. 8 is a temperature change graph of a paper-passing portion and a non-paper-passing portion of the heating body when the paper is passed by the conventional control method.

FIG. 9 is a temperature change graph of the sheet passing portion and the sheet non-passing portion of the heating body during sheet passing according to the control method according to the present invention.

FIG. 10 is a heating body control algorithm of the heating apparatus according to the second embodiment.

FIG. 11 is a heating body temperature change graph showing erroneous detection in the conventional control method.

FIG. 12 is a graph of heating body temperature change in the control method according to the present invention.

FIG. 13 is a graph showing the temperature change of the heating element for each number of sheets passed.

FIG. 14: Heating body control algorithm

FIG. 15: Heated body control algorithm

FIG. 16 is a heating body temperature change graph showing erroneous detection in the conventional control method.

FIG. 17 is a graph showing a temperature change of a heating body in the control system according to the present invention.

FIG. 18: Heated body control algorithm

[Fig. 19] Graph of temperature change of heating element

FIG. 20 is a heating body control flowchart of the heating device according to the third embodiment.

FIG. 21: Heating body temperature change diagram

FIG. 22 is a temperature change diagram of a heating element.

FIG. 23: Temperature chart of heating element

FIG. 24 is a temperature change diagram of a heating body and a pressure roller of the heating device according to the fourth embodiment.

FIG. 25: Heated body control algorithm

FIG. 26 is a diagram showing a paper-to-paper ripple.

FIG. 27 is a diagram showing a paper-to-paper ripple.

FIG. 28 is a diagram showing a temperature change of a heating body during wave number control of the heating device of the fifth embodiment.

FIG. 29 is a diagram illustrating detection timing.

FIG. 30 is a diagram showing a temperature rising rate for each fundamental wave number.

FIG. 31 is a diagram showing a measurement error within the fundamental wave number.

FIG. 32 is a graph showing undetectable time.

FIG. 33 is a diagram showing that the measurement error decreases with time.

FIG. 34 is a diagram for explaining measurement of a heating rate.

FIG. 35 is a diagram for explaining measurement of a heating rate.

[Explanation of symbols]

1 power supply SW 2 noise filter 3 magnetic induction heating fixing control unit 4 low voltage power supply unit 5 temperature sensor 6 fan 7 fan motor driver 8 light receiving element 9 BD circuit 10 high voltage power supply 11 scanner motor 12 scanner motor driver 13 main motor 14 main motor Driver 15 Paper size sensor 16 Paper presence sensor 17 Door sensor 18 Paper feed sensor 21 Video I / F circuit 22 Paper feed solenoid 23 Refeed solenoid 24 Forward / reverse motor driver 25 Forward / reverse motor 28 Refeed sensor 100 Video controller section 101 Host I / F Circuit 103 Video Controller 103a CPU 103b RAM 103c ROM 103d Buffer 103f Nonvolatile Storage Medium 104 Operation Panel 105 Engine Controller 105a CPU 105b RAM 105c ROM 106 Laser driver 107 Radar diode 108 Polygon mirror 109 Mirror 110 Laser light 111 Primary charger 112 Photosensitive drum 113 Developer 114 Transfer charger 115 Cleaning device 116 Magnetic induction heating fixing device 117 Fixing roller (heating body, magnetic metal) Roller 118 118 Pressure roller 120 Paper feed cassette 121 Paper feed roller 1030 High frequency converter (means for applying current to field coil) 1100 to 1103 Field coil 1104 Core material (induction magnetic material) 1205 Control IC (field coil) Means for applying current to the

Claims (22)

[Claims] 1. A heating device for applying a high-frequency magnetic field to a magnetic metal member to cause the magnetic metal member to generate heat by magnetic induction and heat the material to be heated by the heat, wherein the material to be heated is heated at a position to be heated by the material to be heated. When not present, a heating device characterized in that a time for stopping or reducing heat generation of the magnetic metal member is provided, and this time is variable. 2. The time for stopping or reducing the heat generation of the magnetic metal member is variable between the materials to be heated when the materials to be heated are continuously conveyed to the apparatus. The heating device according to claim 1. 3. As a means for determining the time for stopping or reducing the heat generation of the magnetic metal member, the time for stopping or reducing the heat generation of the magnetic metal member is provided in accordance with a predetermined number of continuously conveyed materials to be heated. The heating device according to claim 2, wherein the heating device is a heating device. 4. The heat generation of the magnetic metal member is stopped according to the temperature lowering speed when the heat generation of the magnetic metal member is stopped or reduced as a means for determining the time of stopping or reducing the heat generation of the magnetic metal member. Alternatively, the heating device according to claim 1 or 2, wherein a time for reducing the heating time is provided. 5. A means for detecting an electric power applied to a high frequency magnetic field generating field coil for maintaining the magnetic metal member at a predetermined temperature as a means for determining a time for stopping or reducing heat generation of the magnetic metal member. 3. The method according to claim 1, wherein at least one reference power is provided, and a time period for stopping or reducing heat generation of the magnetic metal member is provided depending on whether the detection power is higher or lower than the reference power. The heating device according to 2. 6. A means for determining the size of the heated material to be conveyed is provided as means for determining the time for stopping or reducing the heat generation of the magnetic metal member, and stopping the heating of the magnetic metal member according to the size of the heated material. The heating device according to claim 1, wherein a time period for reducing the heating time is provided. 7. As a means for determining the time for stopping or reducing the heat generation of the magnetic metal member, the heat generation amount of the magnetic metal member is temporarily increased when the material to be heated does not exist at the position to heat the material to be heated. The heating device according to claim 1, wherein the time for stopping or reducing the subsequent heat generation is determined based on the amount of temperature rise of the magnetic metal member. 8. As a means for determining the time for stopping or reducing the heat generation of the magnetic metal member, the next target is determined according to the rate of temperature rise when the heat generation of the magnetic metal member is stopped or reduced and then reheated. The fixing device according to claim 1, wherein a time for stopping or reducing heat generation due to the heating material is determined. 9. A heating device for applying a high-frequency magnetic field to a magnetic metal member to cause the magnetic metal member to generate heat by magnetic induction and heat the material to be heated by the heat, the device having a temperature detecting means for the magnetic metal member, The means for applying a high frequency current to the magnetic field generating field coil operates so that the temperature detected by the temperature detecting means is maintained at a constant temperature, and when there is no heated material in the heated material heating position of the device, A magnetic metal member temperature control means for stopping the operation of the means for applying a high frequency current to the magnetic coil and changing the control temperature of the magnetic metal member according to the temperature change of the magnetic metal member at that time is provided. A heating device characterized in that the time during which the operation of the means for applying a high-frequency current is stopped is longer than the time during which the temperature change of the magnetic metal member is detected at that time. 10. A heating device for applying a high-frequency magnetic field to a magnetic metal member to cause the magnetic metal member to generate heat by magnetic induction, and heat the material to be heated by the heat. The heating device has a temperature detecting means for the magnetic metal member, The means for applying the high frequency current to the magnetic field generating field coil operates so that the temperature detected by the temperature detecting means is maintained at a constant temperature, and the high frequency magnetic field is generated when the heated material does not exist at the heated position of the heated material of the apparatus. The high frequency magnetic field generating field coil has a magnetic metal member temperature control means for supplying constant power to the generating field coil and changing the control temperature of the magnetic metal member according to the temperature change of the magnetic metal member at that time. A heating device characterized in that the time during which the operation of the means for applying a high-frequency current is stopped is longer than the time during which the temperature change of the magnetic metal member is detected. 11. A heating device for applying a high-frequency magnetic field to a magnetic metal member to cause the magnetic metal member to generate heat by magnetic induction, and heat the material to be heated by the heat, having a temperature detecting means for the magnetic metal member, The means for applying a high-frequency current to the magnetic field generating field coil operates so that the temperature detected by the temperature detecting means is maintained at a constant temperature T ₁ , and when there is no heated material at the heated position for heating the heated material of the apparatus. 'controls the magnetic metal member to, from temperatures T ₁ the temperature T' lower temperature T than the temperature T ₁ of the next object to be heated when it reaches the temperature T 'within a predetermined time after when switching control to The control temperature of the magnetic metal member with respect to the material is T ₁ ,
A heating device characterized in that if the temperature does not reach within a predetermined time, the control temperature of the magnetic metal member for the next material to be heated is set to a temperature T ₂ lower than T ₁ . 12. A heating device for applying a high-frequency magnetic field to a magnetic metal member to cause the magnetic metal member to generate heat by magnetic induction, and to heat a material to be heated by the heat, having a temperature detecting means for the magnetic metal member, The means for applying a high-frequency current to the magnetic field generating field coil operates so that the temperature detected by the temperature detecting means is maintained at a constant temperature T ₁ , and when there is no heated material at the heated position for heating the heated material of the apparatus. the 'controls the magnetic metal member, the control temperature T' temperatures T ₁ lower than the temperature T by measuring the time t until the time that always reaches the control temperature predetermined from the time of reaching, said time t Is longer than a predetermined time, the control temperature of the magnetic metal member for the next material to be heated is T ₂ lower than T _1, and when the time t is less than the predetermined time, the magnetic metal for the next material to be heated is set. The control temperature of the member is T ₁ A heating device characterized by: 13. A heating device for applying a high-frequency magnetic field to a magnetic metal member to cause the magnetic metal member to generate heat by magnetic induction and heat the material to be heated by the heat. The power supplied to the high frequency magnetic field generating field coil when not passing
A heating device which is controlled by h and Low2 values, and determines the control temperature of the magnetic metal member with respect to the material to be heated next entering the heating target material heating position based on the temperature ripple of the magnetic metal member at this time. 14. A heating device for applying a high-frequency magnetic field to a magnetic metal member to cause the magnetic metal member to generate heat by magnetic induction, and heat the material to be heated by the heat. The power supplied to the high frequency magnetic field generating field coil when not passing
Controlled by h and Low2 values, at this High time or Low
A heating device for determining a control temperature of a magnetic metal member with respect to a material to be heated, which enters a heating position of the material to be heated, based on a rate of temperature change. 15. A heating device for applying a high-frequency magnetic field to a magnetic metal member to cause the magnetic metal member to generate heat by magnetic induction and heat the material to be heated by the heat. The power supplied to the high frequency magnetic field generating field coil when not passing
A heating device characterized by controlling with h and Low2 values, and determining the control temperature of the magnetic metal member for the material to be heated next to the heating position based on the peak or bottom of the temperature ripple of the magnetic metal member at this time. . 16. At least one roller of the roller pair pressed against each other is a magnetic metal roller, and a high frequency magnetic field generating field coil and a main coil generated in the field coil are provided inside the magnetic metal roller. An induction magnetic material that is coupled to magnetic flux is provided, and a means for applying a high frequency current is connected to the field coil to apply a high frequency magnetic field to the metal surface of the magnetic metal roller facing the field coil. Causes the magnetic metal roller to generate heat by magnetic induction, and the nip portion of the pressure contact roller pair is positioned as a heating position for the material to be heated, and the material to be heated is nipped and conveyed to the nip portion to heat the material to be heated by heat generated by the magnetic metal roller The heating device according to any one of claims 1 to 15, which is treated. 17. A member forming a nip portion, a magnetic metal member magnetically inducing heat generation by the action of a high frequency magnetic field on at least one of the members forming the nip portion, and a high frequency magnetic field applied to the magnetic metal member at the nip portion. A high-frequency magnetic field generating means for acting is provided, and the material to be heated is nipped and conveyed to the nip portion with the nip portion being a heating position for the material to be heated, and the material to be heated is heat-treated by heat generated by the magnetic metal member. The heating device according to any one of claims 1 to 15. 18. The apparatus according to claim 1, wherein the material to be heated is a recording medium carrying an image to be heat-treated, and the apparatus is an image heating apparatus for heat-processing the image on the recording medium. The heating device according to any one of 17. 19. The image heating process is a heat fixing process for an unfixed image on a recording medium.
The heating device according to 8. 20. A means for forming an image on a recording medium, and the heating device according to claim 1 as an image heating device for heating the image on the recording medium from the image forming means side. An image forming apparatus comprising: 21. The image forming apparatus according to claim 20, wherein the means for forming an image on the recording medium is an electrophotographic process. 22. The image heating process is a heat fixing process of an unfixed image on a recording medium.
The image forming apparatus according to item 0.