JP2022067524A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can prevent a situation in which: when synthetic paper is wound around a fixing member and causes paper jam, high temperature of an external heating member causes excessive heating, which deforms and tears the synthetic paper.SOLUTION: When synthetic paper passes through a fixing nip of a fixing member, an external heating member is not used which is in contact with the fixing member to auxiliarily heats a surface layer.SELECTED DRAWING: Figure 12

Description

The present invention has an image forming means for forming an unfixed toner image on a recording material by a transfer method or a direct method by using an electrophotographic process or the like, and a fixing device for thermally fixing the unfixed toner image on the recording material. However, it relates to an image forming apparatus such as a copier, a facsimile, and a printer for obtaining a hard copy.

In recent years, the types of media that can be passed through for electronic photography have diversified to meet the needs of various customers. Among them, the use of synthetic paper using synthetic resin as the main raw material without using plant fiber has begun to spread. The electrophotographic process, especially the image forming means for forming the above-mentioned unfixed toner on the paper and heat-fixing it, requires various ingenuity in equipment and control in order to enable smooth use of this synthetic paper. be.

In Patent Document 1, when OHT (film paper) is used, the fixing speed is adjusted to enable operation with the optimum amount of heat for the film paper.

On the other hand, there is a demand for high-speed output of paper having a large basis weight. In order to make this request possible, in a large image forming apparatus, an additional heating means from the outside of the member for fixing the unfixed toner to the paper is often used.

In Patent Document 2, the amount of heat supplied to the fixing member is adjusted by determining the attachment / detachment of the heating means from the outside to the fixing member by the basis weight of the paper.

Japanese Unexamined Patent Publication No. 2005-99334 Japanese Unexamined Patent Publication No. 09-197887

Consider the case where synthetic paper is used, and in particular, paper whose rigidity is reduced or deformed due to overheating is used, and a transport failure JAM that wraps around the fixing member occurs due to an external factor. At this time, when there is an external heating member in contact with the fixing member, the synthetic paper wrapped around the fixing member stays between the nips formed by the fixing member of the external heating member or moves to the surface layer of the external heating member. It is possible. Since the externally applied member is set at a higher temperature than the fixing member, the heat-sensitive synthetic paper must avoid contact with the external heating member.

An object of the present invention is to provide an image forming apparatus capable of smooth recovery without applying heat higher than the heat resistant temperature of paper even when wrapping around a fixing member occurs when synthetic paper is used. It is in.

In order to achieve the above object, the image forming apparatus according to claim 1 includes an image forming means for forming an unfixed toner image on paper, a fixing device for heating and fixing the unfixed toner on paper, and the fixing device. , The fixing member pressurizes and heats the unfixed image surface, and it is possible to distinguish between an external heating member that heats the surface layer of the fixing member from the outside and synthetic paper that uses synthetic resin as the main raw material. The feature is that the heating operation from external heating is not performed during the fixing operation when the synthetic paper is selected by the paper type determining unit.

According to the present invention, when synthetic paper is used, even if wrapping around the fixing member occurs due to operation mistakes or variations in paper production, smooth recovery can be performed without applying heat above the heat resistant temperature of the paper. It will be possible.

It is a schematic block diagram of the image forming apparatus which concerns on Example 1. FIG. It is a control block diagram of the image forming apparatus which concerns on this invention. It is a schematic block diagram of the fixing device which concerns on this invention. It is sectional drawing of the standby state of the fixing device which concerns on this invention. It is sectional drawing at the time of fixing operation of the fixing device which concerns on this invention. It is sectional drawing at the time of fixing operation of the fixing device which concerns on this invention. It is sectional drawing at the time of the conventional operation of the fixing device which concerns on this invention. It is sectional drawing at the time of the conventional operation of the fixing device which concerns on this invention. It is sectional drawing at the time of fixing operation of the fixing device which concerns on this invention. It is a fixing paper JAM determination flow which concerns on this invention. It is a fixing paper JAM determination flow which concerns on this invention. It is a flow explaining the feature of the determination which concerns on this invention.

FIG. 1 is an image forming system according to an embodiment of the present invention.

In this embodiment, a solution to the above problems will be described using an electrophotographic laser beam printer. Here, as an example, an electrophotographic method is adopted as an image forming method.

First, the schematic configuration of the image forming apparatus of this embodiment will be described with reference to FIG. The image forming apparatus of the present embodiment can be applied to a copying machine, a printer, a facsimile, a multifunction device having a plurality of these functions, and the like.

[Image forming device]
The image forming apparatus 100 shown in FIG. 1 is a full-color image forming apparatus using an electrophotographic method, and has four image forming units Y (yellow) and M (magenta) that form toner images of four different colors. ), C (cyan), and Bk (black) are arranged. Further, adjacent to these image forming units, an endless intermediate transfer belt 10 as an intermediate transfer body on which the toner images of each color formed by each image forming unit are transferred is arranged. These four image forming units Y, M, C, and Bk have the same configuration, and the configuration of the yellow image forming unit Y will be described below as a representative. For other image forming units, members having the same configuration and operation as the image forming unit Y are given the same number, and the subscripts indicating each unit are changed.

As the image carrier, for example, a cylindrical electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”) 1Y whose surface layer is made of an organic optical semiconductor is rotationally driven in the direction of an arrow. 2Y is a charging roller as a charging means for uniformly and uniformly charging the surface of the photosensitive drum 1Y. The charging roller 2Y to which a predetermined bias is applied is contact-driven and rotated with the photosensitive drum 1Y to charge the surface of the photosensitive drum 1Y to a predetermined potential. The charged photosensitive drum 1Y is exposed to exposure light (laser light, etc.) by the exposure device 3Y to form an electrostatic latent image corresponding to a color-separated image of image data input from a scanner or an external terminal. To. The developing apparatus 4Y develops an electrostatic latent image using the toner carried on the developing sleeve, and forms a toner image corresponding to the electrostatic latent image on the surface of the photosensitive drum 1Y. The toner image on the photosensitive drum 1Y is formed on the intermediate transfer belt 10 by applying the primary transfer bias to the primary transfer roller 5Y in the primary transfer nip portion T1Y between the photosensitive drum 1Y and the intermediate transfer belt 10. Primary transcription.

The primary transfer residual toner on the photosensitive drum 1Y after the primary transfer is removed and recovered by the photosensitive drum cleaning device 6Y in which a blade, a brush, or the like is arranged. Then, the photosensitive drum 1Y from which the primary transfer residual toner has been removed is uniformly and uniformly charged by the charging roller 2Y again and is repeatedly subjected to image formation. The intermediate transfer belt 10 is stretched on the drive roller 11, the support roller 12, and the backup roller 13. Then, the drive roller 11 is rotationally driven by rotation in the arrow direction while contacting the photosensitive drums 1Y, 1M, 1C, and 1Bk of the four image forming units Y, M, C, and Bk.

When the full color mode (full color image formation) is selected, the above image forming operation is executed in each of the four image forming units Y, M, C, and Bk. Then, the yellow toner image, the magenta toner image, the cyan toner image, and the black toner image formed on the photosensitive drums 1Y, 1M, 1C, and 1Bk are sequentially multiple-transferred onto the intermediate transfer belt 10. The color order is not limited to the above, and is arbitrary depending on the image forming apparatus.

Then, the four-color toner image multiplex-transferred on the intermediate transfer belt 10 is conveyed to the secondary transfer unit T2 in which the backup roller 13 and the secondary transfer roller 14 are arranged to face each other via the intermediate transfer belt 10. .. Then, by applying the secondary transfer bias to the secondary transfer roller 4 in the secondary transfer unit T2, the secondary transfer is collectively transferred to the recording material P. The recording material P is, for example, a sheet material such as paper or an OHP sheet, and is housed in a plurality of paper cassettes 40, respectively. Then, the recording material P separated and fed from any one of the plurality of paper cassettes 10 is sent to the secondary transfer unit T2 by the feeding device having the resist roller pair 12, and the multiple transfer toner on the intermediate transfer belt 10 is used. It is supplied at a predetermined control timing according to the image. Here, the image forming apparatus 100 is a recording stored in any one of a plurality of paper cassettes 10 selected by the CPU 81 (see FIG. 3) as a control unit, for example, based on printing conditions (image forming conditions). The material P is conveyed by the feeding device. Further, the image forming apparatus 100 may be configured so that the user selects any one of the plurality of paper cassettes 10. The printing condition is a setting composed of various information such as color number information such as whether the image formed on the recording material P is color or monochrome, and the paper type of the recording material P.

In the present embodiment, the image forming portion that forms an image on the recording material is configured as described above. Then, the image (toner image) formed on the recording material by such an image forming unit, that is, the toner image transferred to the recording material by the secondary transfer unit T2 is conveyed to the fixing device 9 and the recording material P. The unfixed toner image above is pressurized and heated to be fixed on the recording material P. The operation contents of the fixing device at this time will be described later.

The secondary transfer residual toner on the intermediate transfer belt 130 after the secondary transfer is removed and recovered by the intermediate transfer cleaning device 15 in which a blade, a brush, a web (nonwoven fabric), or the like is arranged. Then, the intermediate transfer belt 130 from which the secondary transfer residual toner has been removed is repeatedly subjected to image formation.

The recording material P is discharged to the discharge tray after passing through the transport path. Alternatively, when forming an image on the back surface side, the recording material in which the toner image is fixed on one side is inverted by an inversion path, and then transferred to the secondary transfer section again via the double-sided transfer path, as described above. The toner image is fixed on the back surface side by the process of.

[Fixing device]
FIG. 3 is a diagram showing a schematic cross-sectional configuration of the fixing device 9 according to the present embodiment. Further, the image forming apparatus 100 employs a so-called oilless fixing apparatus by using an image forming apparatus containing a mold release agent in the toner image.

The fixing device 9 has a fixing roller 40 as a rotatable heating rotating body that contacts the surface on which the toner image of the recording material P is formed and heats the image on the recording material P. Further, it has a fixing roller 40 and a pressure roller 41 as a rotatable nip forming member for forming a nip. The fixing device 9 heats the fixing roller 40 with a heating source 40a as a first heat source provided inside the fixing roller 40, and sandwiches and conveys the recording material P carrying the toner image at the nip to transfer the recording material P. It is heated and pressurized to melt the toner image and fix it on the recording material P. The heat source 40a is composed of, for example, a halogen heater, and is controlled by the CPU 81 (see FIG. 2) as a heat source control unit by the temperature of the surface of the fixing roller 40 detected by the temperature sensor 42a as the first temperature detection means. .. For example, the heating source 40a is ON / OFF controlled by the CPU 81, and the surface temperature of the fixing roller 40 is adjusted to a predetermined temperature.

In the present embodiment, the heating source 40a heats the fixing roller 40 so that the surface of the fixing roller 40 maintains, for example, about 160 to 190 ° C. as a predetermined temperature at which the toner image can be fixed on the recording material P. Specifically, the CPU 81 heats the fixing roller 40 by the heating source 40a so that the surface temperature of the fixing roller 40 changes depending on the type of the recording material P or the like.

The fixing roller 40 is formed by providing an elastic layer 40c made of a rubber layer on a hollow metal core shaft 40b as a base layer, and further covering the elastic layer 40c as a surface layer with a release layer 40d. The core shaft 40b is composed of, for example, an aluminum member formed in a cylindrical shape having an outer diameter of 100 mm, and a heating source 40a is arranged inside. The elastic layer 40c is made of, for example, a silicone rubber having a JIS-A hardness of 20 degrees and molded to a thickness of 1.0 mm. The release layer 40d is made of a material having excellent mold release property and softening with increasing temperature, such as a fluororesin formed to a thickness of 50 μm, and covers the elastic layer 40c. As the fluororesin, for example, PFA resin (copolymer of tetrafluoroethylene resin and perfluoroalkoxyethylene resin), PTFE (tetrafluoroethylene resin) and the like are used for the release layer 40d. In this example, a PFA resin tube was used as the release layer 40d. The thickness of the release layer 40d, which is the surface layer of the fixing roller 40, is preferably configured to be, for example, 30 μm to 100 μm. Here, the release layer 40d is not limited to the tube shape, and may be coated with the elastic layer 40c, for example, by coating the elastic layer 40c.

The fixing roller 40 (see FIG. 3) is rotatably supported by support members (not shown) provided at both ends in the longitudinal direction (rotational axis direction) of the core shaft 40b, and is shown by a motor 92 (not shown). It is driven to rotate in the direction of the middle arrow. By being driven by the motor 92, the fixing roller 40 is rotationally driven at a surface movement speed of, for example, 500 mm / sec. In the following description, the surface moving speed of each rotating body is also described as the peripheral speed.

The pressure roller 41 is formed by providing an elastic layer 41b made of a rubber layer on a hollow metal core shaft 41a as a base layer, and further covering the elastic layer 41b as a surface layer with a release layer 41c. The core shaft 41a is composed of, for example, an aluminum member formed in a cylindrical shape having an outer diameter of 70 mm. The elastic layer 41b is made of, for example, a silicone rubber having a JIS-A hardness of 20 degrees and molded to a thickness of 2.0 mm. The release layer 41c is made of a material having excellent mold release properties, such as a fluororesin formed to a thickness of 50 μm, and covers the elastic layer 41b. Here, the release layer 41c is not limited to the structure according to the present embodiment as in the case of the release layer 40d of the fixing roller 40 in terms of the structure for covering the material and the elastic layer 40c. Further, a heating source 41d such as a halogen heater is also arranged inside the pressurizing roller 41, and is controlled by the CPU 81 as a heat source control unit by the temperature of the surface of the pressurizing roller 41 detected by the temperature sensor 42b.

The pressure roller 41 is rotatably supported by support members (not shown) provided at both ends in the longitudinal direction (rotational axis direction) of the core shaft 41a. Further, the support members at both ends of the pressure roller 41 in the longitudinal direction are urged by pressure springs (not shown) as urging means, so that the pressure roller 41 is the fixing roller 40 and the recording material P. A nip having a predetermined width is formed in the transport direction. Further, the pressure roller 41 is driven by the fixing roller 40 to rotate by coming into contact with the fixing roller 40 in this way. In the present embodiment, the pressurizing roller 41 pressurizes the fixing roller 40 with, for example, a total pressure of 1000N. Further, the above-mentioned pressing force may be changed depending on the fixing conditions.

The pressure roller 41 is temperature-controlled at a temperature of about 100 ° C. in a normal standby state. At this time, the fixing roller 40 is separated from the fixing roller 40 while maintaining a constant distance (FIG. 4). When the image information is input and the printing operation is started, the preparation for the fixing operation is started, and about 1 second before the paper reaches the fixing portion, the fixing roller 41 is pressed against the paper. Then, it can be transported and heated (Fig. 3).

Further, in the embodiment of the present invention, an external heating roller unit 38 for directly heating the surface layer of the fixing roller 40 is provided. The external heating unit is controlled by the temperature sensor 42c so that the surface temperature becomes about 210 ° C., and is separated from the fixing roller 40 in the standby state like the pressurizing roller 41. Similarly, when ordinary paper is fixed, it adheres to the fixing roller 40 at almost the same time as the pressing operation of the pressing roller, pressurizes the paper, and is driven to rotate with respect to the surface of the fixing roller 40. Heat is supplied to (Fig. 3).

In particular, when performing a stable printing operation during continuous printing, a heating source such as an external heating roller 42 is required to recover the amount of heat when the surface temperature of the fixing roller 40 drops.

For accurate paper transfer to the fixing device 9, a sensor for detecting the paper position is provided in the paper transfer path. This is an optical reflection type sensor, in which the inlet sensor 65 is arranged on the upstream side of the transfer device and the outlet sensor 66 is arranged on the downstream side of the transfer of the fixing device. When the paper comes to the position of the sensor on the transport path, the reflective sensor detects the reflected light and turns it on. Further, when there is no paper, the irradiating light is strongly reflected and is turned off.

[Control unit]
FIG. 2 is a schematic block diagram showing a control unit provided in the image forming apparatus 100 according to the present embodiment. As shown in FIG. 2, the CPU 81 is electrically connected to a control unit (temperature detection unit 89, heater control unit 90, motor control unit 91) written by the fixing device 9. By being controlled by the CPU 81, the fixing device 9 controls the transport speed of the recording material P, the surface temperature of the fixing roller 40, the pressure roller 41, and the like, and can fix the toner image on the recording material P.

Further, the CPU 81 is also electrically connected to the paper feed cassette 10 and the operation unit 95. When any one of the plurality of paper feed cassettes 10 provided by the CPU 81 is selected based on the printing conditions and the like, the image forming apparatus 100 uses the recording material P stored in the paper feed cassette 10 selected by the CPU 81. Images can be formed. Further, the operation unit 95 accepts operations by the user, and is configured by, for example, a liquid crystal touch panel or the like. The operation unit 95 may be an external terminal such as a personal computer connected to the image forming apparatus 100.

[Paper type settings]
Not limited to the configuration example of the image forming apparatus of this patent. Generally, the equipment that handles paper requires the setting of the paper type.

This is because there are various thicknesses and surface properties of paper, and by optimizing the device settings according to the characteristics of the paper, the optimum settings are supported. For example, untoner can be stably fixed to thick paper or paper having a coat layer by applying a higher temperature with a fixing device.

In the image forming apparatus described in the embodiment, the paper type and the basis weight to be used can be registered in advance from the UI panel unit 200. The paper type displayed on the display unit 102 is selected by the input unit 101. At that time, the characteristics of the paper type can also be selected, and for low melting point paper, the classification of low melting point paper can be selected in the detailed settings even if it is not synthetic paper.

For a long time, as transparent film paper (OHT), paper made of non-pulp raw material mainly made of polyethylene (PET) or polypropylene (PP) has been used.

In recent years, non-transparent synthetic paper made mainly of synthetic resin has become widespread in order to reduce the use of wood pulp and to improve added value such as waterproofing and texture improvement.

The characteristics of these synthetic papers are that they are excellent in weather resistance and water resistance, are not easily torn, and have a glossy feeling, which are advantages that conventional papers do not have. On the other hand, the heat resistance is relatively poor, and when the temperature rises above 160 ° C, it may become soft and deformed, or melt and tear.

[JAM judgment operation]
The operation of the fixing device during the printing operation, which is a prerequisite for using this patent, will be described.

There is no problem if the paper is normally conveyed through the fixing device, but in some cases, transfer failure (JAM) may occur on the way. In particular, when the rigidity of the paper is low, the paper may be wrapped around the fixing member to cause a transport defect, or the tip of the paper may be caught in the transport path, and the paper in the middle may not be transported and may be clogged in the transport path. In particular, JAM in the fixing device requires a quick judgment and a stop operation because the member is heated to a high temperature and is driven under pressure.

The procedure for determining the transfer defect JAM in the area of these fixing devices will be described with reference to the flowchart of FIG.

This is a flow for determining (1) that the tip end portion of the nth sheet of paper is normally conveyed. When there are multiple sheets of paper, the determination flow is performed individually for each sheet. First, the inlet sensor 65, which is an optical sensor, determines that the front end portion of the paper reaches (2). When the tip of the paper reaches the inlet sensor 65, the sensor is shielded from light, so that the time Tn from that point is counted (3). Here, the distance from the inlet sensor 65 to the exit sensor 66 is set to 300 mm. Since the paper transport speed is 400 mm / s, the paper should be fed in 0.75 sec by simple calculation. Here, it is calculated that the transport time does not take 0.80 sec or more even if the fluttering of the paper tip and the detection timing error are taken into consideration.

Therefore, if Tn is within 0.80 sec until the tip of the paper reaches the fixing outlet sensor 66 (4), it is determined that the paper has been normally conveyed, and the determination is completed (5, 6). However, if it exceeds 0.80 sec, it is determined to be JAM at the fixing portion (7). At this time, in order to immediately prevent damage to the member, the energization of all the heaters is turned off (8), the drive of the fixing roller is stopped (9), and the pressure roller 40 and the external heating roller 53 are separated from the fixing roller. (10).

The flow for the determination (11) that the rear end portion of the nth sheet is normally conveyed is also the same determination. This will be described with reference to the flowchart of FIG. Since the light blocking of the sensor is lost at the timing when the rear end is pulled out from the state where the paper is in the sensor portion, the inlet sensor 65 is turned off (12). The time Un from that point is counted (13). Similar to the transport time at the tip, if the Un is within 0.80 sec (14) until the trailing edge of the paper reaches the fixing outlet sensor 66, it is determined that the paper has been normally transported, and the determination is completed (15, 16). ). However, if it exceeds 0.80 sec, it is determined to be JAM at the fixing portion (17). Similarly, the energization of all the heaters is turned off (18), the drive of the fixing roller is stopped (19), and the pressure roller 40 and the external heating roller 53 are separated from the fixing roller (20).

[Explanation of purpose of the embodiment]
Suppose that JAM around the paper fixing roller 40 occurs and the above-mentioned JAM determination is normally performed.

It is assumed that the distance from the fixing pressure nip to the outlet sensor is about 150 mm. Similarly, the distance from the pressure nip of the fixing to the pressure nip of the external heating roller is about 180 mm. If the wound paper is rotated around with the fixing roller as it is, the CPU 81 determines that it is JAM and stops the driving motor 92 of the fixing roller at about 10 mm (0.03 s), or if the deoperation of the external heating roller is not completed, the external heating is performed. The paper will reach the pressurizing nip of the roller (Fig. 7).

If it is a normal paper, it is possible to continuously restart the printing operation only by cleaning the toner stains on the member by appropriately removing the JAM paper. However, in the case of synthetic paper that is sensitive to heat, if the timing of JAM processing is delayed or the paper to be processed is torn off, the paper will be deformed and the members will be damaged, or the paper fragments will be broken. There is a risk that it will remain in the fuser.

In particular, in the case of synthetic paper, the risk of JAM is high on average because the paper tends to soften and deform due to heat and easily wind around the fixing roller 40. Further, when the pressure nip of the external heating member is reached, there is a risk of being exposed to a high temperature by wrapping around the external heating roller having a higher temperature (FIG. 8).

[Operation description of this patent]
In this case, in order to reduce the risk of overheating of these synthetic papers, it was decided to control the external heating so as not to pressurize during the fixing operation.

This will be described according to the determination flow of FIG. First, a flow (21) for determining the type of paper scheduled to reach the fixing device is provided. When the paper type is set to synthetic paper (22), or even if the paper type is set to low melting point paper due to the characteristics of the paper type, external heating is applied to the fixing roller when the paper passes through the fixing nip. On the other hand, it is not pressurized (de-stated) (25) (FIG. 5).

As a supplement to the contents of this patent, since the amount of heat required for external heating is insufficient at that time, it is necessary to take measures to keep the fixing temperature control above a certain level, such as widening the space between papers during continuous printing (26). There is. Also at this time, if the synthetic paper does not reach the fixing nip, for example, external heating may be applied at the timing between the papers to raise the temperature of the fixing roller, or the pressure roller may be temporarily removed. If possible, demoving the fixing roller will speed up the temperature recovery of the fixing roller.

That is, the external heating roller 53 pressurizes the fixing roller 40 before the above-mentioned paper reaches the fixing nip (FIG. 3), but does not perform the pressurizing operation (FIG. 5), thereby temporarily fixing the paper. Even if the paper is wrapped around the roller, the influence on the fixing member 40 and the surrounding members can be minimized without being affected by the external heating roller that becomes hot.

[Supplementary explanation of the operation of this patent]
If it is normal paper, there is no problem even if an external heating member is used, so the operation of attaching the external heating roller in advance is returned (24).

In addition, even when multiple types of paper are mixed, by repeatedly attaching and detaching the external heating roller, it is possible to eliminate the greatest risk of synthetic paper during JAM while minimizing the decrease in productivity. It is possible.

In the above explanation, a simple example is described in which the external heating roller is not attached when the synthetic paper is passed. In the actual control, in addition to the contents of this explanation, for example, when the external heating member is configured to be pressurized against the fixing roller, the surface temperature of the external heating member is set to be equal to or lower than the surface temperature of the fixing member. By doing so (that is, the heating operation from the external heating member to the fixing member is not performed), the risk at the time of winding can be reduced.

Further, if the arrangement of the paper sensor is devised, the fixing member may be stopped at the timing when the JAM is detected, so that the paper tip may be stopped before reaching the external heating member. However, considering the time lag from when the motor is stopped until the motor drive operation actually stops, and when the motor becomes faster, the arrangement of the sensor members and the brake configuration of the drive motor become complicated. Can be considered.

P Recording paper T Toner 1 Developer 3 Photosensitive drum 8 Upstream fuser 9 Downstream fuser 10 Paper deck 11 Secondary transfer roller 24 Temporary transfer roller 38 External heating unit 40 Fixing roller 41 Pressurizing roller 53 External heating roller 65 Inlet Sensor 66 Outlet sensor 92 Fixing roller drive motor 93 Pressurizing roller attachment / detachment motor 94 External heating unit attachment / detachment motor 100 Image forming device 200 Operation unit

Claims (6)

An image forming means for forming an unfixed toner image on paper,
A fixing device that heats and fixes the unfixed toner to paper,
The fixing device has a configuration in which a fixing member pressurizes and heats an unfixed image surface.
An external heating member that heats the surface layer of the fixing member from the outside,
Equipped with a paper type discriminator that can discriminate synthetic paper that uses synthetic resin as the main raw material.
An image forming apparatus characterized in that a heating operation from external heating is not performed during a fixing operation when synthetic paper is selected by the paper type determining unit. The image forming apparatus according to claim 1, wherein the external heating member is not brought into contact with the fixing member as a configuration that does not perform the heating operation from the external heating. The image forming apparatus according to claim 1, wherein the surface temperature of the external heating member is set to be equal to or lower than the surface temperature of the fixing member so as not to perform the heating operation from the external heating. The image forming apparatus according to claim 1, wherein the paper type determining unit is a paper type setting set in the device. The image forming apparatus according to claim 1, wherein the paper type determining unit is an item of paper type characteristics for individually setting paper characteristics. The image forming apparatus according to claim 1, wherein the paper type determining unit is an item of a paper type database prepared in advance.

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