JPH0825611A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To provide an electrophtographic device capable of printing to a booklet having a larger thickness than that of recording paper. CONSTITUTION:A toner image formed on a photosensitive drum 22 is transferred on a transfer-fixing film 27 having heat resistance and conductivity, and the transfer-fixing film 27 Is interposed between a heating body 6 and a booklet 21 and then the transfer fixing film 27 and heating body G are pressed, so that a toner image is transfer-fixed on the booklet 21 through heat of the heating body 6. The heating body 6 is formed either to be movable in contact or non-contact relation with respect to the recording surface of the booklet 21, or to change compressing forces of the heating body 6 according to the printing position of the booklet 21. with line result that printing can be finely effected to a booklet whose thickness changes with the page to be recorded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine and a laser printer, and more particularly to a copying machine and a laser printer capable of printing on a booklet.

[0002]

2. Description of the Related Art Conventionally, when forming an image in a copying machine, a laser printer or the like, for example, US Pat. No. 2,297,691 or the Electrophotographic Society, "Basics and Applications of Electrophotographic Technology"
The electrophotographic recording method by the Carlson method as described in (Corona Publishing, June 15, 1988: P.47) is used.

As an example of this method, a conceptual diagram of a conventional image forming process configuration is shown in FIG.

In this method, the image on the original read by the optical means is exposed by the exposure device 52 on the surface of the photosensitive drum 56 charged by the corona discharge of the corona discharger 53 to form an electrostatic latent image. It is formed. The electrostatic latent image is formed on the photosensitive drum 56, for example, in a state of being charged with a positive charge. Next, the electrostatic latent image having the positive charge is supplied with the toner having the negative charge by the developing device 51 and developed as a toner image.

The toner image on the photosensitive drum 56 is transferred to the recording paper 57 which is in contact with the photosensitive drum 56. In this method, a charge having a polarity opposite to the charging polarity of the toner 60a, that is, a positive charge is applied to the recording paper 57 from the back side of the recording paper 57 by the transfer device 50, and the toner image is transferred to the recording paper by electrostatic force. is there. The transferred toner image is subjected to heat or pressure by a fixing device including a heating roller 58 and a pressure roller 59, and is fused to the recording paper 57 to form an image 60b.

Since the photosensitive drum 56 is repeatedly used as it rotates, a static eliminator 55 and a cleaning device 54 are provided for cleaning the residual toner after transfer.

[0007]

As is apparent from the above image forming process, in this method, the recording paper is held between the photosensitive drum and the transfer device. This transfer device applies an electric potential opposite to that of the photosensitive drum from the back side of the toner transfer surface of the recording paper in order to apply an electrostatic force that attracts the charged carrier on the photosensitive drum or the charged toner to the recording paper. ing. Therefore, in a medium such as a thick recording paper or a thick booklet, even if an electric potential is applied from the back side of the recording paper or the booklet, the surface potential does not rise and a sufficient electrostatic force cannot be applied. Therefore, it is impossible to print on thick paper, booklets, etc. by the above method.

An object of the present invention is to provide an electrophotographic apparatus capable of recording print information on a thick recording medium such as a booklet, and a transfer fixing method thereof.

[0009]

As means for achieving the above object, there are the following modes for electrophotographic apparatuses.

(1) In an electrophotographic apparatus comprising a transfer body for adhering and holding a toner image based on print information, and a fixing means for transferring and fixing the toner image of the transfer body onto a recording medium, The changing recording media can be handled.

(2) In (1), the recording medium of which the thickness changes is a booklet.

(3) An electrophotographic apparatus comprising: a transfer member that adheres and holds a toner image based on print information; and a fixing unit that transfers and fixes the toner image of the transfer member onto a recording medium, wherein the recording medium Is a booklet, and the fixing means is movably provided in accordance with a change in the thickness of the booklet that is conveyed so that the stitch portion of the booklet is perpendicular to the conveying direction.

(4) In an electrophotographic apparatus comprising a transfer body for adhering and holding a toner image based on print information, and a fixing means for transferring and fixing the toner image of the transfer body onto a recording medium, the transfer body Is movable so as to come into contact with and separate from the printing surface of the recording medium.

(5). In (4), the recording medium is a booklet.

(6) An electrophotographic apparatus comprising a transfer member for adhering and holding a toner image based on print information, and a fixing unit for transferring and fixing the toner image of the transfer member onto a recording medium, wherein the recording medium Is a booklet, and the fixing means is provided with a heating element forming a part thereof so as to be able to come into contact with and separate from the booklet.

(7). In an electrophotographic apparatus comprising a transfer body that adheres and holds a toner image based on print information, and a fixing unit that transfers and fixes the toner image of the transfer body onto a recording medium, the transfer body In order to transfer and fix the above toner image onto the recording medium, the pressing force of the heating element provided in the fixing means against the recording medium is changed.

In (8) and (7), the recording medium is a booklet, and the pressing force is changed according to the thickness and step of the booklet.

(9). In any one of (1) to (8), the fixing means includes a heating element, a spring that supports the heating element, and a drive source that moves the heating element.

In (10) and (9), a PTC thermistor is used as the heating element.

(11). In (10), a plurality of PTC thermistors are used.

In (12) and (10), a plurality of the PTC thermistors are used, and the plurality of PTC thermistors are provided so as to control their respective heat generation.

(13). In any one of (1), (3), (4), (6), and (7), the transfer member has an endless belt shape.

(14). In any one of (1), (3), (4), (6), and (7), the transfer member is in the form of an endless belt, and a heating element and a heating element are provided inside thereof. The fixing means including the spring for supporting and the driving source for moving the heating element is arranged.

In (15). (12) or (13), the endless belt-shaped transfer member is a polyimide film having a tetrafluoroethylene layer on the surface on which the toner image is transferred.

(16). In (12) or (13), the endless belt-shaped transfer member has a polyimide film as a core material, an ethylene tetrafluoride layer on the surface on which the toner image is transferred, and the other surface. Has a metal coating layer.

(17). In (14) or (15), carbon is mixed in the polyimide film.

In any one of (18). (2), (3), (5), (6), and (8), a storage unit for storing the format to be written in the booklet is provided.

(19). A photosensitive drum that forms a toner image based on print information, a charging unit that charges the photosensitive drum, and an exposure unit that forms an electrostatic latent image based on the print information on the photosensitive drum. Developing means for forming a toner image by attaching toner to the electrostatic latent image, transfer means for transferring the toner image onto a transfer body, and fixing means for transferring and fixing the toner image on the transfer body onto a recording medium. An electrophotographic apparatus including a conveying roller for conveying a recording medium, the photosensitive drum, the charging unit, the exposing unit, and the photosensitive drum based on the print information, the recording medium information, and the information from the recording medium position detecting unit.
The developing means, the transfer means, the fixing means, and the control means for controlling the driving of the conveying roller are provided, and the fixing means is configured to be movable in the print surface direction of the recording medium, and is moved by a signal from the control means.

Further, as a means for achieving the above object, there are the following aspects regarding the transfer fixing method of the electrophotographic apparatus.

(20). A photosensitive drum for forming a toner image based on print information, a transfer means for transferring the toner image onto a transfer body, and a fixing means for transferring and fixing the toner image on the transfer body onto a recording medium. In a transfer fixing method of an electrophotographic apparatus, comprising: a conveyance roller configured to convey a recording medium, and transferring and fixing a toner image based on print information to the recording medium, a recording medium from a sensor arranged on a front side in a conveying direction of the fixing unit. The position of the recording medium is calculated from the passing signal and the rotation angle of the conveying roller arranged on the front side of the sensor in the conveying direction, and the fixing unit is configured so as to come into contact with and separate from the printing surface of the recording medium via the transfer body. The heating element that operates in the above step is brought into contact with or separated from the recording medium according to the calculated position of the recording medium.

(21). A photosensitive drum for forming a toner image based on print information, a transfer means for transferring the toner image onto a transfer body, and a fixing means for transferring and fixing the toner image on the transfer body onto a recording medium. In a transfer fixing method of an electrophotographic apparatus, comprising: a conveyance roller configured to convey a recording medium, and transferring and fixing a toner image based on print information to the recording medium, a recording medium from a sensor arranged on a front side in a conveying direction of the fixing unit. A heating element that calculates the position of the recording medium from the passing signal and the rotation angle of the conveying roller arranged on the front side in the conveying direction of the sensor, constitutes the fixing means, and presses the printing surface of the recording medium via the transfer body. The pressing force of is changed according to the calculated position of the recording medium.

(22). A photosensitive drum for forming a toner image based on print information, a transfer means for transferring the toner image onto a transfer body, and a fixing means for transferring and fixing the toner image on the transfer body onto a recording medium. In a transfer fixing method of an electrophotographic apparatus, comprising: a conveying roller that conveys a recording medium, and transferring and fixing a toner image based on print information to the recording medium, the fixing unit constitutes the fixing unit, and the transfer body is provided on a printing surface of the recording medium. A backup roller that faces the heating element that transfers heat via the transfer medium and holds the recording medium between the transfer element and the movable roller in a direction away from the heating element. Move to.

(23). In any one of (20) to (22),
The recording medium is a booklet, and includes a storage unit that stores a format to be written in the booklet, and prints the format and the print information stored in the storage unit on the booklet in an overlapping manner as necessary. .

(24). In (21), the recording medium is a booklet, and when the booklet is conveyed in a direction perpendicular to the conveying direction of the recording medium, the pressing force is applied in the vicinity of the booklet portion. Higher and lower on both sides.

[0035]

According to the present invention, in the developing step, a toner image is formed by adhering toner onto the transfer body which is moved in contact with the photosensitive drum, and in the fixing step the toner on the transfer body is formed. An image constitutes PTC (Positi
ve Temperature Coefficient) A toner image is recorded because it is pressed against the recording medium by a heating element such as a thermistor and a backup roller arranged to face the heating element and is melted by the heating of the heating element and transferred and fixed to the recording medium. The transfer and fixing onto the medium can be performed only in one direction of the recording medium, that is, from the recording surface side. Further, since the fixing means can move in the contacting and separating directions with respect to the recording surface, printing can be easily performed even on a recording medium such as a booklet which has a thickness and the thickness of which changes depending on the location. At this time, when printing on the spread part of the booklet and also on the vicinity of the binding part, in order to cope with the thickness change near the binding part, the pressing force in the vicinity of the binding part should be higher than other parts. When printing is performed, it is possible to suppress local changes in curvature and bulge and to improve printing position accuracy.

Further, when printing on a booklet or the like having a binding portion, the heating element can be separated from the booklet when printing in the vicinity of the binding portion is unnecessary. Is formed on the transfer body and only the booklet is conveyed to the unprinted portion, the use frequency of the transfer body can be reduced and the life of the film forming the transfer body can be increased.

By forming the film in the shape of an endless belt, the shape of the heating element that comes into contact with the recording medium through the film is not limited, and the contact portion can be made flat so that transfer and fixing can be stably performed. Further, when polyimide is used as the film, it has heat resistance, so that it is hardly stretched or deformed by heat, and high transfer accuracy is maintained. The ethylene tetrafluoride layer arranged on the toner image transfer surface of the film has good releasability, so that the toner is surely transferred to the recording medium side at the time of transfer. The metal film layer provided on the surface of the film opposite to the toner image transfer surface is connected to the ground to prevent electric charges from remaining on the polyimide layer. It is further effective to mix carbon that enhances conductivity into the polyimide layer.

Even if the surface of the recording medium cannot be heated, a plurality of PTC thermistors constituting the heating element can be separately current-controlled to perform partial heating. For example, PET (polyethylene terephthalate) or Even if there is a heat-sensitive material such as a seal, printing can be performed without affecting them. Further, the heat-sensitive portion may be moved in the direction in which the heating element or the backup roller is separated from the recording medium.

A required format such as a recording frame and characters to be recorded on the recording medium is stored in advance, and for example, when the page is first printed, the content of the format is printed together with the print content, so that a blank sheet can be used as a recording medium. It is possible to use those in the state of.

[0040]

EXAMPLES An example of the present invention will be described below.

FIG. 1 is a block diagram of the printing mechanism section of the electrophotographic apparatus of the present invention. The first guide, paper pan 1
The second guide, which is composed of the paper guide 11 and the paper guide 19, which are opposed to the first guide and the second guide at a distance, forms a conveyance path for conveying the booklet 21. The distance between the first guide and the second guide is determined to be wider than the maximum thickness of the booklet or the like to be conveyed. In this transport path, transport drive rollers 10,
20 and transport driven rollers 9 and 1 that face the drive roller
8 are provided. The driven rollers 9 and 18 are supported by elastic members 8 and 17, respectively.
7 is a driven roller 9 supported by drive sources 7 and 16;
18 controls the force pushing the booklet 21. If the booklet 21 to be handled is thin or has low conveyance resistance,
Since the driven rollers 9 and 18 can be conveyed without moving up and down, the drive sources 7 and 16 may be omitted.

Further, in order to have a stronger carrying force,
The driven rollers 9 and 18 may be drive rollers.
The sensors 13 and 15 are provided to detect the entry of the booklet into the printing section and to position the booklet 21.

The heating element 6 uses a PTC thermistor, and is supported by the drive source 4 and the elastic member 5, and the backup roller 14 is opposed to it via the paper pan 12.
Further, the heating element 6 has a rounded shape on both sides in the booklet transport direction on the side in contact with the booklet, and can easily follow the portion where the thickness changes.

A thick film heater may be used instead of the PTC thermistor. In this case, the PTC thermistor did not require temperature control, but the thick film heater requires a temperature control circuit and a temperature sensor.

The elastic members 8, 17 and 5 are preferably springs, particularly compression springs.

Solenoids may be used as the drive sources 4, 7 and 16.

The transfer / fixing film 27, which is a transfer member to which the toner is transferred from the photosensitive drum, is formed in the shape of an endless belt, and is wound around rollers 1, 2, and 3 to rotate. In this embodiment, the roller 2 is the driving roller, but any of the rollers 1, 2 and 3 may be the driving roller. The endless belt-shaped transfer / fixing film 27, which does not extend in the length direction and is easily deformed, allows the heating element 6 to make the portion in contact with the booklet 21 flat, and thus the transfer / fixing to the booklet. Is stable.

A charging device 23, an exposing device 24, and a developing device 25 are close to the photosensitive drum 22, and the toner 26 is electrostatically transferred from the developing device 25 to the photosensitive drum 22 to form a toner image. The photosensitive drum 22 and the transfer / fixing film 27 are provided with toner removing means 28B and 28a for removing residual toner, respectively. It should be noted that the transfer fixing film 27 is configured so as not to separate from the transfer fixing film 27 in conjunction with the movement of the roller 1.

The distance L between the transport rollers 10 and 20 is L.
0 may be set to be at least shorter than the length in the transport direction when the booklet 21 is closed. By setting in this way, it is possible to print on the cover.

In the present embodiment, the booklet is conveyed in the direction perpendicular to the binding portion of the booklet. However, when it is conveyed in the direction parallel to the binding portion of the booklet, it is set shorter than the length in the binding portion of the booklet. Good.

The operation will be described with reference to FIGS.

When the booklet 21 is conveyed on the paper pan 12 in the direction A by the conveying rollers 18 and 20, the sensor 1
5 detects the booklet 21.

Further, the booklet 21 is conveyed and stopped at a predetermined position sandwiched by the heat-generating body 6 which is the transfer and fixing section, the transfer and fixing film 27 and the backup roller 14. The photosensitive drum 22 receives a rotational force from the roller 2 that is in contact with the transfer fixing film 27 and rotates in the B direction, and the surface thereof has a charging process by the charger 23 and an electrostatic latent image forming process by the exposure device 24. Then, a series of toner image forming processes by the developing device 25 are performed (FIG. 2).

Next, the toner image on the photosensitive drum 22 is transferred onto the transfer fixing film 27 moving in the C direction while rotating the photosensitive drum 22. At this time, the transfer roller is
A voltage is applied by the power supply 210 to generate an electrostatic force.

In order to fix the toner image on the transfer / fixing film 27 to the booklet 21, the roller 1 moves in the D direction, and in synchronization with this, the driving source 4 is kept keeping the tension of the transfer / fixing film 27 almost constant. This moves the heating element 6 and the spring 5 in the E direction. In order to keep this tension constant, the roller 3
Is elastically supported by an elastic member such as a spring, or a tension sensor for measuring the tension of the transfer fixing film 27 is provided,
The displacement amount of the transport roller 1 and the drive source 4 is controlled by this sensor signal.

As a result, the transfix film 27 comes into contact with the booklet 21. The toner 26 of the toner image on the contact surface is heated from the back surface of the transfer fixing film 27 by the heating element 6 and is pressed against the booklet 21 by the drive source 4 and the spring 5 at an arbitrary pressure. Therefore, the booklet 21 is held between the transfer fixing film 27 and the backup roller 14. As a result, the toner image on the transfer / fixing film 27 is melted by heat and transferred and fixed on the paper surface of the booklet 21 by the pressure when held.

Booklet 2 from the moment this booklet 21 is held
1 is again conveyed in the A direction. The speed at which the booklet 21 moves in the A direction and the speed at which the transfix film 27 moves in the C direction are the same (FIG. 3). In this state,
The toner is transferred and fixed on a predetermined portion of the booklet 21, and printing is performed.

When the heating element 6 approaches the binding portion 21a of the booklet 21, the drive source 4 moves the heating element 6 and the spring 5 in the E'direction, and the roller 1 also moves in the D'direction, so that the booklet 21 is moved. And the transfer fixing film 27 are brought into a non-contact state.
(Figure 4).

At this time, if the toner image to be transferred to the transfer-fixing film is preliminarily set only on the printing portion, the transfer-fixing film is stopped from being conveyed, and only the booklet is conveyed, the heat load on the heat-transfer film is reduced. The life of the transfix film is extended.

The approaching state of the heating element 6 to the binding portion 21a of the booklet 21 depends on the size of the booklet 21 measured separately and the sensor 1
Judgment is made based on the movement amount of the booklet from 5. The size of the booklet is calculated from, for example, a sensor arranged at the booklet insertion port and the like, and the conveyance speed of the booklet.

When it is also necessary to print near the binding portion 21a of the booklet 21, the transfer fixing film 27 is conveyed in the printing state shown in FIG. 3 without moving the heating element 6 and the roller 1. In the vicinity of the binding part, the pressing force is larger than the pressing force when printing on the flat part. The reason is that in the vicinity of the binding portion 21a of the booklet 21, a bulge is often present,
This is for printing by suppressing this bulge.

When the binding portion 21a of the booklet 21 has passed, the heat source 6 again moves in the E direction by the drive source 4, and the roller 1 moves in the D direction, so that the transfer fixing film 27 is applied to the booklet. Contact and start printing. At this time, both of them are moved so that the tension of the transfix film 27 is kept substantially constant.
(Figure 5).

When the toner image on the transfer / fixing belt 27 disappears or a command to finish printing is issued, the drive source 4 moves the spring 5 and the heating element 6 in the E'direction, and the roller 1 moves in the D'direction. Moving. Then, the booklet 21 is transported in the A direction on the paper pan 12 by the transport rollers 9 and 10 in order to perform the following processing (FIG. 6).

Printing on the booklet is performed by such a procedure.

When the transfer fixing film 27 is thermally deformed, the toner image is disturbed. Therefore, at least the glass transition temperature Tf of the transfix film 27 must be higher than the glass transition temperature Tf of the toner, which is a thermoplastic polymer. Since the glass transition temperature of toner is generally around 100 ° C., a thermosetting polyimide having no glass transition temperature or a thermoplastic polyimide having a glass transition temperature of 200 ° C. or higher is preferable as a material for the transfix film.

7 to 9 show examples of passbooks used in financial institutions such as banks as an example of printed booklets.

FIG. 7 shows a schematic perspective view of a passbook. Passbook 3
On the surface of 0, a magnetic stripe 32 and a protective film 31 such as PET (polyethylene terephthalate) for protecting the magnetic stripe 32 are attached. Generally, PET has a glass transition temperature of 100 ° C. or lower. PTC
If a heating element such as a thermistor contacts in a heated state, PE
T may be heated to about 150 to 200 ° C., and the adhesive surface between the PET and the magnetic stripe is displaced due to thermal deformation. After shrinkage, wrinkles are likely to occur.

Therefore, at the time of transferring and fixing the toner onto the surface of the booklet, it is necessary to heat except the portion where the protective film 31 is attached.

In the electrophotographic apparatus of this embodiment, the passbook 30
Is conveyed in the A direction and contacts the transfix film at a strip-shaped contact portion perpendicular to the A direction, for example, the contact surface 33.
As shown in the figure, the heatable region is a region having a length Wh from the end of the passbook 30, and the heat exclusion region is a region having a length Wn from the end of the passbook 30.

FIG. 8 is a schematic sectional view including the protective film portion of the passbook shown in FIG. The passbook 30 includes a cover 30a and a middle paper 3 which are made of cotton cloth and paper, which are generally called cloth materials.
0b, magnetic stripe 32, and protective film 3 such as PET
It consists of 1.

FIG. 9 shows a passbook 35 having specifications different from those of the passbook 30 shown in FIG.

As shown in the figure, the magnetic stripe 36 is
In a strip shape in a direction orthogonal to the transport direction (direction A) of the passbook 35,
In addition, it is stuck to the end of the passbook in the transport direction.
When printing on the surface of this passbook, since the range of the length Lh from the end of the passbook 35 is a heatable region, the transfer fixing film 27 comes into contact with the passbook 35, but the length Ln after that is the same. Since the range is a heating exclusion area, heating to the protective film can be prevented by making it non-contact. Although heating can be prevented by not heating the heating element while the transfer / fixing film 27 is in contact, the non-contact is more effective.

Next, the structure of the transfer fixing film and the outline of the transfer process will be described with reference to FIGS. 10 and 11.

FIG. 10 is a schematic sectional view showing an example of the structure of the transfer / fixing film 27. In consideration of the releasability of the toner, an ethylene tetrafluoride layer 40 disposed on the surface to which the toner is transferred, It is composed of a carbon mixed polyimide layer 41 in consideration of conductivity and heat resistance.

As shown in the figure, the toner 26a on the photosensitive drum 22 moves onto the ethylene tetrafluoride layer 40 by the electrostatic force between the photosensitive drum 22 and the conductive transfer and fixing film 27, and the toner 26b. Adhere like. The carbon mixed in the polyimide layer 41 imparts conductivity to the originally non-conductive polyimide, and grounding of the polyimide layer prevents the transfer fixing film from being charged up. .

FIG. 11 is a schematic sectional view of a transfix film according to an embodiment of the present invention. This transfer fixing film has a structure in which, in addition to the tetrafluoroethylene layer 42 and the polyimide layer 43 shown in FIG. 10, a metal coating layer 44 is arranged on the surface of the polyimide layer 43 opposite to the tetrafluoroethylene layer.

Since the metal coating layer 44 is disposed so as to be in close contact with the polyimide layer 43, there is no gap between the two layers, and the grounding of the polyimide layer 43 can be surely taken by the metal coating layer 44.

13 to 15 show the structure of the heating element 6. As the heating element 6, a heating element chip composed of a PTC thermistor (hereinafter referred to as PTC heating element chip) is used. FIG. 13 shows a perspective view of the PTC heating element chip 70. The PTC heating element chip 70 has a rectangular parallelepiped shape, and electrodes are provided on the upper and lower surfaces thereof. The electrodes are provided with two divided electrodes 71a and 71b with a predetermined width from both ends in the lateral direction on the upper surface, and an electrode 72 is provided on the entire lower surface.

FIG. 14 shows a schematic diagram of wiring to the PTC heating element chip 70. A power source 90 is connected to the divided electrodes 71a and 71b.
The electric wire 81 is bonded or pressure-bonded to be electrically connected.

The surface of the whole surface electrode 72 is adhered to the heat dissipation surface of the heat dissipation plate.

FIG. 15 is a perspective view showing the structure of the heating element 6. The heating element 6 can be divided into three parts: a heating element 74, a holder 75, and an elastic element 77. The general manufacturing method is
The heating body 74, the elastic body 77, and the holder 75 are connected in this order with an adhesive so that the heating body 74 and the elastic body 77 are fitted into the recesses of the holder 75 in this order. The adhesive is preferably an adhesive having elasticity and heat insulation and electric insulation. In this embodiment, a silicone adhesive is used, but a polyimide adhesive may be used. Aluminum was used for the holder 75.

The elastic body 77 is provided so that the heating body 74 can stably contact the transfer and fixing belt 27 even if the holder 75 is thermally deformed. In this embodiment, a silicon rubber plate is used. Any material that has elasticity and good heat resistance may be used.
Alternatively, a metal leaf spring or a coiled spring may be used.

In the heating element 74, the heat radiating plate 80 is adhered to the entire surface of the electrode of the PTC exothermic element chip 70 by using an adhesive having excellent thermal conductivity and electrical insulation. In addition, the split electrode 7
The electric wire 81 described with reference to FIG. 14 was adhered to the surface forming the 1a and 71b. Note that the electric connection of the electric wires may be performed by pressure bonding instead of adhesion. The side surfaces other than the heat dissipation plate are covered with a frame 76 made of a concave heat insulating material to prevent heat transfer to the holder 75.

As shown in FIG. 15, a plurality of PTC heating element chips 70 are arranged in series in the longitudinal direction. Therefore, each PTC heating element chip 70 can be independently heated. Further, by combining PTC heating element chips having different Curie points, the heating temperature distribution of the heating element can be set arbitrarily.

According to the present embodiment, it is possible to perform printing from the printing surface side even on a recording medium having a thickness, and it is possible to easily perform printing on a recording medium whose thickness changes. Further, since the heating element can be moved away from the recording medium at the time of recording, if there is a portion where recording is unnecessary, the life of the transfix film can be extended by pressing only the recording medium without pressing the heating element. .

The structure and operation of the electrophotographic apparatus of another embodiment of the present invention will be described with reference to FIGS. 16 to 21.

As shown in FIG. 16, in the electrophotographic apparatus of this embodiment, a backup roller opposed to the heating element 6 is movably provided in contrast to the above-mentioned embodiment so that the transfer fixing film side is not moved. The difference is that the above embodiment is different. The first guide, the paper pan 12, and the second guides, the paper guide 11 and the paper guide 19,
By these, the conveyance path which conveys the booklet 21 is formed.
In the transport path, transport drive rollers 10, 2 are used as transport means.
0 and the driven rollers 9 and 18 that are in contact with the driving roller are provided. The driven rollers 9 and 18 are supported by springs 8 and 17, respectively. The springs 8 and 17 are supported by the driving sources 7 and 16 and are driven by the driven rollers 9 and 1.
8 controls the force pushing the booklet 21.

If the booklet 21 is thin, the drive sources 7 and 16 may be omitted. Further, in order to give a stronger carrying force, it is preferable to change the driven rollers 9 and 18 to drive rollers.

The sensors 13 and 15 are arranged to detect the state of entry of the booklet into the printing section and to position the booklet 21. The heating element 6 is supported by the spring 5 so as to apply a predetermined pressing force to the booklet, and the paper pan 12
It is opposed to the backup roller 81 via the.

In this embodiment, a PTC thermistor is used as the heating element. Further, the spring is preferably a compression coil spring, and other elastic body such as rubber may be used.

The backup roller 81 is supported by a drive source 84 for displacing a solenoid or the like for pressing the surface of the booklet 21 against the belt-shaped transfer and fixing film 27 and a spring 83 for controlling the pressing force. The paper guide 11 is arranged in the vicinity of the heating element 6 so that the booklet 21 pressed against the transfer fixing film 27 can be properly returned to the transport path.

The transfer / fixing belt 27 includes rollers 1, 2, 3
Further, it is wound around by the heating element 6 and the driving force is obtained by the driving roller 2.

The charging device 23, the exposing device 24, and the developing device 25 are close to the photosensitive drum 22, and the toner 26 is electrostatically transferred from the developing device 25 to the photosensitive drum 22 to form a toner image. The interval L0 between the central axes of the transport rollers 10 and 20 is at least shorter than the length in the transport direction when the booklet 21 is open. Further, when the front cover is printed, the interval L0 must be shorter than the length in the transport direction when the booklet is closed.

The booklet 21 is conveyed in the direction A on the paper pan 12 by the conveying rollers 18 and 20, and the sensor 15
However, it stops when the booklet 21 is detected.

The photosensitive drum 22 rotates in the rotation direction B as the driving roller 2 rotates, and the charger 2 onto the photosensitive drum 2 rotates.
The charging process by 3 and the electrostatic latent image forming process by the exposing device 24, and the toner image forming process on the photosensitive drum 22 by the developing device 25 are performed (FIG. 17).

Further, the toner image on the photosensitive drum 22 is transferred onto the transfer / fixing film 27 moving in the C direction. The conveyance of the booklet is started so that the transferred toner image is printed at the position where the booklet should be printed. When the booklet approaches the transfer fixing unit sandwiched between the heating element 6 and the backup roller 81, in order to fix the toner image on the transfer fixing film 27 to the booklet 21, the drive source 84 moves the backup roller in the F direction. Move to. As a result, the transfix film 27 comes into contact with the booklet 21. The toner 26 of the toner image on the transfer / fixing film 27 is heated by the heating element 6 from the back surface of the transfer / fixing film 27, and is pressed against the booklet 21 by the drive source 84 and the spring 83 at an arbitrary pressure. Therefore, the booklet 21 is held between the transfer-fixing film 27 and the backup roller 81, and the toner image on the transfer-fixing film 27 is transferred and fixed on the paper surface of the booklet 21. Match the speed at which the booklet 21 moves in the A direction with the speed at which the transfix film 27 moves in the C direction (see FIG. 1).
8).

Then, the booklet 21 is conveyed in the A direction,
When the binding portion 21 a of the booklet 21 approaches the vicinity of the heating element 6, the drive source 84 causes the backup roller 81 and the spring 83 to move.
Moves in the F'direction to move the booklet 21 and the transfix film 27.
Becomes a non-contact state (FIG. 19). If it is necessary to print near the binding portion 21a of the booklet 21, the transfix film 27 is pressed with a force larger than the pressing force at the time of printing. This is because the binding portion 21a of the booklet 21 is dented at the binding portion and the front and rear sides of the binding portion 21a are raised in a curved shape. This is because it is necessary to correct the curved surface into a flat surface by pressing force. This pressing force depends on the rigidity of the booklet, the binding method, and the number of pages of the booklet.

After passing the vicinity of the binding portion 21a of the booklet 21, the backup roller 81 is again moved in the F direction to press the booklet against the heating element. At this time, the pressing force of the backup roller 81 is controlled by the drive source 84 (FIG. 20).

When the toner image on the transfer / fixing belt 27 is exhausted or a command to finish printing is issued, the drive source 84 returns the backup roller 81 to the F'direction.

The booklet 21 is conveyed in the A direction on the paper pan 12 by the conveying rollers 9 and 10 in order to perform the following processing (FIG. 21).

According to the present embodiment, it is not necessary to move the transfer / fixing film and the heating element, only the backup roller needs to be moved, and there is an effect that the structure is simpler than that of the above embodiment.

As another embodiment of the present invention, a booklet printer will be described with reference to FIG. In the present embodiment, a case will be described in which the binding portion of the booklet is inserted into the printer in a direction orthogonal to the transport direction of the booklet.

The booklet printer 200 has at least an insertion port 100 for inserting a booklet and a pair of conveying rollers 1 for conveying the booklet inserted from the insertion port 100.
02 and 103, 127 and 124, 106 and 10
7, a transport path that passes through three pairs of transport rollers from the insertion port 100,
The magnetic information reading unit 104 for reading the magnetic information recorded in the booklet, the magnetic information recognition unit 130 that recognizes the magnetic information read by the magnetic information reading unit 104 and sends the information to the data interface, The image information reading unit 105 for reading an image, the image information recognition unit 131 for recognizing the image information read by the image information reading unit 105 and sending the information to the data interface, the conveying rollers 102, 127 and 1
06 and 116 and the drive motor 108 that rotationally drives the backup roller 109 that faces the heating element 111, the photosensitive drum 121 described in the above embodiment, and the charger 12.
0, exposure device 119 composed of laser or LED, developing device 1
18, transfer fixing film 136, transfer fixing film 13
Rollers 115, 122, 116 for conveying 6 and heating element 1
11, a spring 112, a drive source 113 for driving the heating element 111 in a direction to press it against the booklet, paper guides 128, 12
6, sensors 101, 12 for detecting the position of the booklet
3, 110, a magnetic information recognition unit 130, an image information recognition unit 131, and a data interface 132 for receiving signals from each sensor, a data interface 13
The driving source 11 based on the calculation result from the calculation unit 134 and the calculation unit for calculating the information of No. 2 and transmitting the result to the control unit.
3, roller 115, photosensitive drum 121, developing device 118,
The exposure unit 119 and a control unit 134 that sends a control signal to the drive motor 108 to control their operation are provided.

The calculation unit 134 sends the booklet information from the data interface to a computer (not shown), the computer receives print data calculated based on the information separately input by the customer, and sends the data to the control unit. You may do it. Booklet 1 inserted in the direction A with the page to be printed opened from the insertion slot 100
When 37 is detected by the sensor 101, the conveyance roller is rotated by a signal from the control unit 134 to convey the booklet inside. The transport rollers may be rotated at the same time, or only those that contribute to the transport of the booklet may be operated.

The transported booklet has a magnetic information reading unit 10
4 reads the information written on the magnetic stripe attached to the cover of the booklet, the information is recognized by the magnetic information recognition unit 130, and then the image information reading unit 105.
Page information of the page to be printed with, that is, how many pages to print,
The print information such as the number of lines up to which printing has been completed is read, and the image information recognition unit 131 recognizes the image information.

Based on the information of the magnetic information recognizing unit 130 and the image information reading unit 105, the computing unit determines whether printing is possible. When printing, a working signal to each working unit is sent according to a predetermined procedure based on print data sent from a computer (not shown) to the arithmetic unit, and print data is sent to the exposure unit, and a laser or LED is placed on the photosensitive drum.
The print data is written by the exposure device using the (Light-emitting diode), and the data is printed on the booklet according to the procedure described in the above embodiment. The sensor 11 prints on the booklet.
The amount of booklet movement is calculated from the output of 0 and the rotation angle of the drive motor 108 to calculate the position of the booklet. Further, the pressing force is changed based on the amount of movement of the booklet according to the position of the booklet before the binding portion, the vicinity of the binding portion, and the position after the binding portion. When it is not necessary to print near the binding portion, the heating element is retracted as described above.

When the arithmetic unit determines that it is necessary to print the format including the predetermined frames and columns and the necessary characters and numbers on the booklet 137, the arithmetic unit determines the format printing information and the information to be written in the format. Thirteen
Overlap at 3 and print. This format print information is stored in the ROM or the like.

The print data is subjected to font development in the arithmetic unit 133, and the photosensitive drum 121 charged by the charger 120 is exposed by an exposing device such as a laser or an LED, and the developing device 118 exposes a toner image. Is formed.

This toner image is transferred onto a transfer fixing film having conductivity and toner releasability, which is made of a polyimide film having tetrafluoroethylene arranged on the surface. The transferred toner images are transferred to the transport rollers 115, 116, 12
It is fixed on the booklet by the heat-generating body 111 which is moved by the transfer fixing film which is kept at a constant tension by 2 and is conveyed, and which is pressed against the backup roller 109 by the drive source 113 and the spring 112.

The calculation unit 133 calculates the thickness of the booklet from the magnetic information and the image information, and as described above, the sensor 1
The position of the booklet is calculated from the rotation angles of 23 and the drive motor 108.

The calculation unit 133 sends a pressing force control command to the driving source 113 based on the thickness, shape, printing position, etc. of the booklet 137. By this instruction, control such as increasing the pressing force in the vicinity of the binding portion of the booklet 137 or changing the pressing force according to the thickness when printing on the booklet 137 is performed. Booklet 137
As shown in FIG. 24, the binding portion is in a direction orthogonal to the transport direction A direction. As a result, the binding portion swells, which causes a difference in thickness at each value in the transport direction.

FIG. 23 shows the pressing force required for printing on a booklet having 10 pages to be printed, depending on the printing position.
Is displayed when the number of pages on the side to be inserted is one, that is, when there are nine remaining pages after the binding portion. "1
In the case of `` sheets '', set the pressing force low at least to the binding part,
The vicinity of the binding portion is set to be high, and the pressing force beyond the binding portion is set to be slightly higher. Also, in the case of “10 sheets”, “1
Contrary to the case of "sheets", the beginning is made slightly higher, and the binding part is made higher and then lower. Further, the pressing force may be made different between the portion far from the binding portion and the portion near the binding portion. By performing such pressing force control, it becomes possible to accurately print lines, figures, characters, etc. within each page having different thicknesses. The pressing force control pattern is stored in the control unit in advance, and a predetermined pattern is used according to the number of pages of the booklet to be handled. The number of pages of the booklet is put in the cover of the booklet as magnetic information,
Read at the time of insertion or use a booklet with a fixed number of pages.

The toner that has not contributed to printing on the photosensitive drum 121 is removed by the cleaner 117b. Further, the toner not transferred and fixed on the transfer / fixing film 136 is removed by the cleaner 117a.

The booklet 201 shown in FIG. 24 is format-printed by the booklet printer 200 shown in FIG. Format printing is to print columns 202 for date, symbol, amount A, amount B, balance, etc. on a blank booklet as shown in FIG. 24, for example.

In the booklet 201, the thickness of the booklet with the binding portion 203 as a boundary differs depending on the page. Further, in the vicinity of the binding portion 203, the booklet is likely to have a bulge. Therefore, by controlling the pressing force at the time of fixing as described above, the toner image on the film can be fixed on the booklet without being deformed.

According to the present embodiment, when printing on the spread portion of a booklet or the like, even if the thickness changes depending on the printing position, it is possible to change the pressing force and perform printing accurately under conditions suitable for the printing position. Information on a booklet and the format of the booklet can be printed at the same time, and it is possible to appropriately respond to a change in the booklet format.

[0117]

As described above, according to the present invention, since printing on the recording medium can be performed from the printing surface side, it is possible to provide an electrophotographic apparatus capable of printing regardless of the thickness of the recording medium. In addition, even for booklets such as passbooks that require printing on double-page spreads that have a change in thickness, the heating element can be moved so as to move toward and away from the recording medium, or the thickness of the printed portion Since the pressing force can be changed depending on the size, it is possible to provide an electrophotographic apparatus that can perform accurate printing.

[Brief description of drawings]

FIG. 1 is a side view illustrating a mechanical portion of an electrophotographic apparatus showing an embodiment of the present invention.

FIG. 2 is a side view explaining the operation of the electrophotographic apparatus shown in FIG.

FIG. 3 is a side view illustrating the operation of the electrophotographic apparatus shown in FIG.

FIG. 4 is a side view illustrating the operation of the electrophotographic apparatus shown in FIG.

5 is a side view illustrating the operation of the electrophotographic apparatus shown in FIG.

6 is a side view for explaining the operation of the electrophotographic apparatus shown in FIG.

FIG. 7 is a perspective view showing an example of a booklet used in the electrophotographic apparatus of the present invention.

FIG. 8 is a side view showing an example of a booklet used in the electrophotographic apparatus of the present invention.

FIG. 9 is a perspective view showing an example of a booklet used in the electrophotographic apparatus of the present invention.

FIG. 10 is a diagram illustrating a transfer process and a structure of a transfer fixing film according to the present invention.

FIG. 11 is a diagram illustrating the structure of a transfer process and a transfer fixing film according to the present invention.

FIG. 12 is a configuration diagram illustrating a conventional image forming process.

FIG. 13 is a perspective view of a PTC heating element chip used in the present invention.

FIG. 14 is a schematic view illustrating wiring of a PTC heating element chip used in the present invention.

FIG. 15 is a configuration diagram of a heating element used in the present invention.

FIG. 16 is a side view illustrating a mechanical portion of an electrophotographic apparatus showing an embodiment of the present invention.

FIG. 17 is a side view explaining the operation of the electrophotographic apparatus shown in FIG.

FIG. 18 is a side view explaining the operation of the electrophotographic apparatus shown in FIG.

FIG. 19 is a side view illustrating the operation of the electrophotographic apparatus shown in FIG.

20 is a side view for explaining the operation of the electrophotographic apparatus shown in FIG.

21 is a side view for explaining the operation of the electrophotographic apparatus shown in FIG.

FIG. 22 is a configuration diagram of a booklet printer showing an embodiment of the present invention.

FIG. 23 is a diagram illustrating a control amount of pressing force in the device of the present invention.

FIG. 24 is a perspective view showing an example of a booklet that is format-printed by the apparatus of the present invention.

[Explanation of symbols]

6 ... Heating element, 11 ... Paper guide, 12 ... Paper pan,
13 ... Sensor, 14 ... Backup roller, 15 ... Sensor, 19 ... Paper guide, 21 ... Booklet, 22 ... Photosensitive drum, 23 ... Charging device, 24 ... Exposure device, 25 ... Developing device,
26 ... Toner, 27 ... Transfer fixing film, 100 ... Insertion port, 101, 110, 123 ... Sensor, 102, 10
3, 106, 107, 127, 124 ... Conveying rollers, 1
04 ... Magnetic information reading / writing device, 105 ... Image information reading device, 108 ... Motor, 109 ... Backup roller, 111 ... Heating element, 112 ... Spring, 113 ... Drive source, 115, 116, 117, 122 ... Film transport roller, 117 ... Developer, 119 ... Laser / LED, 12
0 ... Charger, 121 ... Photosensitive drum, 128 ... Paper guide, 130 ... Magnetic information recognition unit, 131 ... Image information recognition unit, 132 ... Interface unit, 133 ... Computing unit,
134 ... Operation unit, 135 ... Conveyance path, 136 ... Transfer fixing film, booklet ... 137, 200 ... Booklet printer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Riki Hiraoka 502 Jinritsu-cho, Tsuchiura-shi, Ibaraki Prefecture Hiritsu Seisakusho Co., Ltd. (72) Inventor Masaru Nakano 502 Jinre-cho, Tsuchiura-shi, Ibaraki Hiritsu Seisakusho Co., Ltd. Mechanical Research Laboratory (72) Inventor Takao Terayama 502 Jinritsucho, Tsuchiura-shi, Ibaraki Hiritsu Manufacturing Co., Ltd. Mechanical Research Laboratory (72) Minoru Murakoshi Ikegami, Haruoka-cho, Owariasahi-shi, Aichi Hitachi, Ltd. Office Systems Business In-house (72) Inventor Shigeki Numata 1 Ikegami, Haruoka-cho, Owariasahi-shi, Aichi Prefecture Hitachi Ltd. Office Systems Division

Claims (24)

[Claims] 1. An electrophotographic apparatus, comprising: a transfer member that adheres and holds a toner image based on print information; and a fixing unit that transfers and fixes the toner image of the transfer member onto a recording medium.
An electrophotographic apparatus capable of handling a recording medium having a variable thickness. 2. The electrophotographic apparatus according to claim 1, wherein the recording medium whose thickness changes is a booklet. 3. An electrophotographic apparatus, comprising: a transfer member that adheres and holds a toner image based on print information; and a fixing unit that transfers and fixes the toner image of the transfer member onto a recording medium.
The electrophotographic apparatus is characterized in that the recording medium is a booklet, and the fixing means is movably provided in accordance with a change in thickness of a booklet conveyed such that a stitch portion of the booklet is perpendicular to the conveying direction. .. 4. An electrophotographic apparatus, comprising: a transfer member that adheres and holds a toner image based on print information; and a fixing unit that transfers and fixes the toner image of the transfer member onto a recording medium.
The electrophotographic apparatus, wherein the transfer member is movable so as to come into contact with and separate from a printing surface of the recording medium. 5. The electrophotographic apparatus according to claim 4, wherein the recording medium is a booklet. 6. An electrophotographic apparatus, comprising: a transfer member that adheres and holds a toner image based on print information; and a fixing unit that transfers and fixes the toner image of the transfer member onto a recording medium.
The electrophotographic apparatus, wherein the recording medium is a booklet, and the fixing means is provided with a heating element forming a part thereof so as to be capable of coming into contact with and separating from the booklet. 7. An electrophotographic apparatus, comprising: a transfer member that adheres and holds a toner image based on print information; and a fixing unit that transfers and fixes the toner image of the transfer member onto a recording medium.
An electrophotographic apparatus characterized in that a pressing force of a heating element provided in a fixing means for transferring and fixing the toner image on the transfer medium to a recording medium is changed to the recording medium. 8. The electrophotographic apparatus according to claim 7, wherein the recording medium is a booklet, and the pressing force is changed according to a thickness and a step of the booklet. 9. The electrophotographic apparatus according to claim 1, wherein the fixing unit includes a heating element, a spring that supports the heating element, and a drive source that moves the heating element. 10. The heating element according to claim 9, wherein the heating element is PTC.
An electrophotographic apparatus using a thermistor. 11. The electrophotographic apparatus according to claim 10, wherein a plurality of PTC thermistors are used. 12. An electrophotographic apparatus according to claim 10, wherein a plurality of the PTC thermistors are used, and the plurality of PTC thermistors are provided so that heat generation of each of them can be controlled. 13. The electrophotographic apparatus according to claim 1, wherein the transfer member has an endless belt shape. 14. The transfer member according to claim 1, wherein the transfer member has an endless belt shape, and a heating element, a spring supporting the heating element, and a heating element are moved inside thereof. An electrophotographic apparatus, wherein a fixing unit having a driving source is arranged. 15. The electrophotographic apparatus according to claim 13 or 14, wherein the endless belt-shaped transfer member is a polyimide film having a tetrafluoroethylene layer on a surface on which a toner image is transferred. 16. The endless belt-shaped transfer member according to claim 13 or 14, wherein the polyimide film is a core material,
An electrophotographic apparatus comprising an ethylene tetrafluoride layer on a surface to which a toner image is transferred and a metal film layer on the other surface. 17. The electrophotographic apparatus according to claim 15, wherein carbon is mixed in the polyimide film. 18. An electrophotographic apparatus according to any one of claims 2, 3, 5, 6 and 8, further comprising a storage section in which a format written in the booklet is stored. 19. A photosensitive drum for forming a toner image based on print information, a charging unit for charging the photosensitive drum, an exposing unit for forming an electrostatic latent image on the photosensitive drum based on the print information, Developing means for forming a toner image by attaching toner to the electrostatic latent image, transfer means for transferring the toner image onto a transfer body, fixing means for transferring and fixing the toner image on the transfer body onto a recording medium, and recording In an electrophotographic apparatus including a conveyance roller that conveys a medium, the print information,
The fixing means is provided with a control means for controlling the drive of the photosensitive drum, the charging means, the exposing means, the developing means, the transfer means, the fixing means and the conveying roller according to the information of the recording medium and the information from the position detecting means of the recording medium. Is configured to be movable in the printing surface direction of the recording medium, and is moved by a signal from the control means. 20. A photosensitive drum for forming a toner image based on print information, transfer means for transferring the toner image onto a transfer body, fixing means for transferring and fixing the toner image on the transfer body onto a recording medium, and recording. In a transfer fixing method of an electrophotographic apparatus for transferring and fixing a toner image based on print information to a recording medium, the recording medium passing signal from a sensor arranged on the front side in the conveying direction of the fixing means. Then, the position of the recording medium is calculated from the rotation angle of the conveying roller arranged on the front side of the sensor in the conveying direction, and the fixing unit is configured to operate so as to come into contact with and separate from the printing surface of the recording medium via the transfer body. A transfer fixing method for an electrophotographic apparatus, characterized in that the heating element is brought into contact with or separated from the recording medium according to the calculated position of the recording medium. 21. A photosensitive drum for forming a toner image based on print information, a transfer means for transferring the toner image onto a transfer body, a fixing means for transferring and fixing the toner image on the transfer body onto a recording medium, and recording. In a transfer fixing method of an electrophotographic apparatus, which comprises a carrying roller for carrying a medium, and transfers and fixes a toner image based on print information to a recording medium, a recording medium passing signal from a sensor arranged on the front side in the carrying direction of the fixing means. And the position of the recording medium is calculated from the rotation angle of the conveying roller arranged on the front side of the sensor in the conveying direction, and constitutes the fixing means and presses the heating element which presses against the printing surface of the recording medium via the transfer body. A transfer fixing method for an electrophotographic apparatus, wherein the pressure is changed according to the calculated position of the recording medium. 22. A photosensitive drum for forming a toner image based on print information, a transfer means for transferring the toner image onto a transfer body, a fixing means for transferring and fixing the toner image on the transfer body onto a recording medium, and recording. A transfer fixing method for an electrophotographic apparatus, comprising: a transfer roller configured to transfer a medium, and transferring and fixing a toner image based on print information to a recording medium. A backup roller that faces the heating element that transfers heat and that holds the recording medium between it and the transfer element and that can move in the direction away from the heating element is moved in the direction away from the heating element during recording on the recording medium. A method of transferring and fixing an electrophotographic apparatus, which comprises: 23. The recording medium according to any one of claims 20 to 22, wherein the recording medium is a booklet, and a storage unit for storing a format to be written in the booklet is provided. A transfer-fixing method for an electrophotographic apparatus, characterized in that a stored format and print information are superimposed and printed. 24. The recording medium according to claim 21, wherein the recording medium is a booklet, and when the booklet is conveyed in a direction perpendicular to the conveyance direction of the recording medium, the pressing force is increased near the binding portion. A transfer fixing method for an electrophotographic apparatus, characterized in that the height is lowered on both sides.