JPH06308861A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device provided with a color vanishing means capable of surely vanishing color even when a color vanishing speed is made to coincide with the carrying speed of an image forming side. CONSTITUTION:In the image forming device having the toner color vanishing means for a paper sheet 14 on which an image is formed with color vanishing toner 15, the color vanishing means is composed of heating members 8 and 13 provided on a paper carrying path and light irradiation members 1 and 2, as a characteristic. Therefore, as the color vanishing means, the heating means and the light irradiation means are provided so that toner is heated by the heating means, to activate the activity of the molecule of a color vanishing colorant and then, irradiation with prescribed light is executed by the light irradiation means, to vanish the color. Thus, the color vanishing properties of the color vanishing toner 15 are improved (the improvement of the color vanishing speed) and even when the color vanishing speed is made to coincide with the carrying speed of the image forming part side, the color can be surely vanished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus provided with an erasing means (erasing device) for erasing the toner of a sheet on which an image is formed with an erasing toner.

[0002]

2. Description of the Related Art In recent years, paper wastes discharged from offices have been attracting attention from the viewpoint of resource conservation in the problem of wastes becoming serious. The recycling of paper, so-called OA paper, is being called for. Recycling of OA paper, which is currently being carried out, means that the OA paper used for copying or printers is sorted and collected, and then it is reused as recycled paper after being subjected to dissolution, deinking, and papermaking at paper mills and the like. is there. However, at present, it is said that only about 5% of the OA paper consumed in offices of 2.5 million tons per year is collected.

On the other hand, OA in an office is such that OA paper is printed with a recording material such as toner or ink using a decolorizable colorant, and is erased and printed again when it is no longer needed.
Paper recycling is proposed. The outline of this decolorizable colorant is a recording material using a colorant composed of a cyanine dye and an ammonium salt of organic boron, for example, in an electrophotographic image forming apparatus, the above-mentioned colorant is used instead of carbon black as a colorant. When using a toner with a colorant,
Under general illumination, blue printing is possible, and the same visibility as in normal recording can be obtained. In this print recording method, the colorant can be made colorless by irradiating light near 820 nm, so that the recording can be erased. Therefore, by using such a decolorizable colorant recording material,
It is said that recycled paper can be reused relatively easily, which is effective for resource conservation, environmental conservation, and reduction of municipal solid waste.

[0004]

Regarding a concrete system for reusing OA paper using decoloring toner, the technology disclosed heretofore is dedicated to decoloring the image of the decoloring toner formed on the paper. Erasing device was required. In this case, since the image forming apparatus and the erasing apparatus are installed in the operating environment, the installation space is large, and there are many work procedures in which the sheets erased by the erasing apparatus are set again in the image forming apparatus. Therefore, it is conceivable that the image forming apparatus and the erasing apparatus are integrated. In this case, in order to immediately reuse the sheet that has been subjected to the erasing processing by the erasing apparatus in the image forming section, the conveyance speed of the image forming apparatus and The erasing speed of the erasing device must be the same. However, in order to erase the color-erasable toner, it is necessary to irradiate light having a wavelength of around 820 nm for a predetermined time as described above, and therefore the color-erasing is not sufficiently performed because the normal conveying speed of the image forming apparatus is too fast. The problem occurs.

The present invention has been made in view of the above circumstances, and an image provided with an erasing means capable of surely erasing even if the erasing processing speed is matched with the conveying speed on the image forming section side. An object is to provide a forming device.

[0006]

In order to achieve the above object, the invention of claim 1 is an image forming apparatus having a toner erasing means for a sheet on which an image is formed with a erasing toner. It is characterized by being constituted by a heating member provided in the sheet conveyance path and a light irradiation member.

According to a second aspect of the present invention, in an image forming apparatus having a toner erasing means for a sheet on which an image is formed with a erasing toner, the erasing means includes a heating member having a built-in heat generating member, and a pressurizing member which is pressed against the heating member. It is characterized in that it is composed of a member and a lamp for irradiating a predetermined light on the conveying surface downstream of the conveying path of these heating means.

According to a third aspect of the present invention, in an image forming apparatus having a toner erasing means for a sheet on which an image is formed with a erasing toner, the erasing means heats and heats a light-transmissive material containing a light emitting member. And a light irradiating member and a pressure member that is in pressure contact with the light irradiating member, and the heat generating and light emitting members are surrounded by a reflecting plate that collects light after the pressure contacting portion or the transportation route thereof. .

According to a fourth aspect of the present invention, in an image forming apparatus having a toner erasing means for a sheet on which an image is formed with a erasing toner, the erasing means includes a fixing roller having a heat generating member and a pressure roller in pressure contact with the fixing roller. The fixing roller of the fixing device is composed of a color erasing roller made of a light-transmitting material and having a light emitting member built-in, which is pressed against the pressure roller at the downstream side of the conveying path.

According to a fifth aspect of the present invention, in the image forming apparatus having the toner erasing means for the sheet on which the image is formed with the erasing toner, the erasing means is located upstream of the image forming unit of the image forming apparatus in the conveying path. In addition, the paper passes through the erasing means at least twice before the paper reaches the image forming means.

According to a sixth aspect of the invention, in the image forming apparatus according to the fifth aspect, the heating member and the light irradiating member pass through the first erasing means, and the light irradiating member passes through the second and subsequent times. Characterized by passing only through.

[0012]

In the image forming apparatus according to the first to fourth aspects, the decoloring means is provided with a heating means and a light irradiating means, and the toner is heated by the heating means to activate the molecular activity of the decolorizable colorant. After that, the light irradiating means can irradiate a predetermined light for erasing, so that the erasing property of the erasing toner can be improved and the erasing speed can be improved. Further, in the image forming apparatus according to the fifth and sixth aspects, the light irradiation time can be secured by transporting the erasing device a plurality of times, and the erasing speed can be improved.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the illustrated embodiments. (1) Configuration of Image Forming Apparatus FIG. 1 is a diagram showing an embodiment of the present invention, which is an erasing apparatus integrally provided with an image forming section (laser printer section) using a laser and an erasing section. It is a schematic structure figure showing the composition of a built-in printer. In FIG. 1, the printer unit includes a laser generator 17, an optical system 18 that focuses the laser light from the laser generator 17 to a predetermined position, and a reflecting mirror 19 that reflects the output light of the optical system 18. The photosensitive drum 20 to which the beam from the reflecting mirror 19 is exposed, the charger 21 that uniformly charges the photosensitive body 20 before the exposure, and the electrostatic latent image formed on the photosensitive drum by the exposure A developing device 22a for developing with black toner and a developing device 22b for developing with decolorizing toner, a resist roller 23 for feeding the transfer paper to the transfer position at a timing, and a cassette 24 for setting a large number of transfer papers, Cassettes 25 for trial printing in which a large number of sheets of paper that have been copied or printed with decoloring toner are set, and a paper feed roller 26 that feeds out only one sheet from each cassette. 27, the photosensitive drum 20 to the transfer sheet fed from the registration rollers 23
A transfer charger 28 for transferring the upper toner image, a separation charger 29 for removing the portion of the paper after transfer is completed and peeling it from the photoconductor drum 20, a conveyor belt 30 for conveying the peeled transferred paper, and this conveyor belt. A fixing device 31 for fixing the unfixed toner image adhering to the transferred sheet conveyed by 30 and a cleaning device 3 for removing the residual toner adhering to the surface of the photosensitive drum 20.
2 and a discharge tray 33 that stores the transferred paper from the fixing device 31. Further, the erasing unit erases the image of the paper that has been copied or printed with the erasing toner, the erasing device 34 that conveys the paper that has passed through the erasing device 34, and the erasing paper. An intermediate tray 37 that is temporarily stacked and a switching claw 36 that switches the transport path from the intermediate tray 37 to the registration roller 23. The configuration of the erasing device 34 will be described later.

(2) Operation of the printer unit In FIG. 1, in the printer unit, the laser generator 17 is modulated and driven according to the image information, and the laser light is transmitted to the optical system 18,
The latent image is formed by reaching the photosensitive drum 20 which is charged in advance by the charging charger 21 through the reflecting mirror 19. This latent image reaches the position where the developing devices 22a and 22b face each other in response to the rotation of the photosensitive drum 20, and toner development is performed on the latent image with either black toner or decoloring toner. The transfer sheet sent out from the cassette 24 or the sheet sent out from the trial printing cassette 25 and passed through the erasing device 34 is registered at the registration roller 23 at a timing when the visible image by toner development reaches the transfer position. The toner image on the photoconductor drum 20 is attracted to the paper surface by the transfer charger 28 at the transfer position. The transfer-completed paper is separated from the leading edge of the paper by the separation charger 29, and the transfer belt 3
Sent to 0. The paper on the conveyor belt 30 is carried into the fixing device 31, and heat and pressure are applied by a pair of fixing rollers (a heat fixing roller and a pressure roller) of the fixing device 31 to fix the toner image on the paper surface. . The sheet on which the fixing is completed is sent to the discharge tray 33.

(3) Decoloring speed of decoloring toner image By the way, an image formed by decoloring toner is 820n
The color can be erased by irradiating light (infrared light) near m. Since this light is also included in natural light and room light, if an image copied or printed with decoloring toner is left as it is, the image density gradually decreases and the visibility deteriorates. Therefore, the erasing property is sacrificed to some extent, and the erasing speed by the erasing device becomes longer than the image forming speed. Here, FIG.
Heating element and 600W halogen lamp (decoloring lamp)
2 shows the decoloring speed of toner (conveying speed of the decoloring device) by the decoloring device using and. In the case of one-time paper passing, when there is no heating by the heating member, the erasing speed is 5 mm / s or less,
The printer shown in FIG. 1 cannot be mounted when the transport speed is 60 mm / s. However, it has been found that by heating the decoloring toner by a heating member (heating roller or the like), a chemical change of the decoloring toner is promoted, and as a result, the decoloring speed can be increased. Furthermore, by passing the erasing device twice, the erasing speed doubles and the erasing speed of 60 m
It has been found that m / s is possible. Therefore, in the present invention, the erasing device incorporated in the image forming apparatus as shown in FIG. 1 is configured with a heating member and a light irradiating member to improve the erasing speed. This is to ensure that the color is erased by using paper. Hereinafter, a specific configuration example of the erasing device will be described.

(4) Configuration and Operation I of Decoloring Device (Claims 1 and 3) FIG. 2 is a schematic configuration diagram showing an example of the decoloring device. This decoloring device includes a decoloring lamp 1 for decoloring toner, a reflector 2 for concentrating the light of the decoloring lamp 1 on a decolored toner image 15 on a sheet 14, and a sheet 14 for conveying and erasing the sheet 14. Color lamp 1
The light-transmissive roller 3 that applies the second light to the paper 14, the pressure roller 4 that press-contacts the light-transmissive roller 3 and is driven to rotate to convey the paper 14, and the paper 14 is separated from the light-transmissive roller 3. It is composed of a separating claw 5. In FIG. 2, the erasing lamp 1 is a halogen lamp, and also has a function as a heat source for heating the light transmitting roller 3. Further, it is of course possible to provide a decoloring lamp and a heat generating lamp other than this configuration. Further, each lamp may be provided around the light transmissive roller 3. Since the light of the erasing lamp 1 is focused on the paper, the reflector 2 has a focal point on the roller pressure contact portion where the paper is sufficiently heated to enhance the erasing effect or on the downstream side of the transport path. The light-transmitting roller 3 is made of a heat-resistant and infrared-transmitting material (for example, glass), and the surface layer is covered with a fluororesin (colorless and transparent) so that the toner melted by heat does not easily adhere. Since the pressure roller 4 is in pressure contact with the light-transmitting roller 3, heat resistance and elasticity are required. Therefore, the configuration is such that the silicone rubber is wound around the metal core (same configuration as the pressure roller of the heat roller fixing device). The separating claws 5 are made of heat-resistant resin (the same structure as the separating claws of the heat roller fixing device), and a plurality of separating claws 5 are arranged in the roller axial direction.

Next, the erasing operation by the erasing device shown in FIG. 2 will be described. When the decoloring device is on standby, the temperature is detected by a thermistor or the like (not shown) in contact with the surface of the light-transmitting roller 3, and the decoloring lamp 1 is turned on and off by a temperature adjusting circuit (not shown). Controlled to 120 ° C. When the sheet 14 is carried into the erasing device, the erasing lamp 1 interrupts the ON-OFF control and is turned on. Therefore, the sheet is irradiated with predetermined light while being heated by the light-transmitting roller 3, and the decolorized toner image 15
Is erased.

(5) Configuration and Operation of Decoloring Device II (Claims 1 and 2) Next, FIG. 3 is a schematic configuration diagram showing another configuration example of the decoloring device. This erasing device includes a heating roller 13 for applying heat and pressure, a halogen lamp heater 8 for heating the heating roller 13 to a predetermined temperature, and a heating roller 1 upstream of a conveyance path.
Pressure roller 10 that is pressed against 3 and rotates following the heating roller.
A cleaning roller 7 for cleaning the toner adhering to the surface layer of the heating roller 13 and a separation claw 12 for separating the heating roller 13 and the paper 14, and a decoloring lamp for decoloring the toner downstream of the conveying path. 1 and a reflector 2 for concentrating the light of the erasing lamp 1 on the paper. The heating roller 13 is made of an aluminum material, and its surface layer is covered with a fluororesin so that the toner melted by heat does not easily adhere thereto.

Next, the erasing operation by the erasing device shown in FIG. 3 will be described. When the decoloring device is on standby, the temperature is detected by a thermistor or the like (not shown) contacting the surface of the heating roller 13, and the halogen lamp 8 is turned on and off by a temperature adjusting circuit (not shown).
Controlled by. At this time, the erasing lamp 1 is off
Has become. When the paper 14 is carried into the erasing device, the erasing lamp 1 is turned on, the paper 14 is heated by the heating roller 13 and conveyed in the erasing lamp direction, and the erasing lamp 1 emits a predetermined light to erase the paper. The color toner image 15 is erased.

(6) Structure and Operation of Decoloring Device III (Claims 1 and 4) Next, FIG. 4 is a schematic structural diagram showing a structural example of a heat fixing device which also functions as a heat roller fixing device and a erasing device. Is. This heat fixing device includes a fixing roller 9 for applying heat and pressure to the unfixed image surface of the sheet on which the toner image is transferred, a halogen lamp heater 8 for heating the fixing roller 9 to a predetermined temperature, and a fixing roller 9. A pressure roller 10 that is pressed against the fixing roller 9 and is driven to rotate, an oil application roller 11 that applies a small amount of silicone oil to the surface layer of the fixing roller 9 and cleans the toner adhering to the surface layer, and a separation that separates the fixing roller and the sheet. As shown in the drawing, the claw 12 is further provided, and as shown in the figure, the light-transmitting roller 3 having the decoloring lamp 1 and the reflecting plate 2 built therein and the separating claw 5 are provided. The fixing roller 9 is pressed against the fixing roller 9.

According to this structure, when the paper is set in the cassette of the image forming apparatus so that the back surface (white paper surface) of the paper 14 already image-formed with the decoloring toner becomes the image forming surface, the image forming apparatus operates. Unfixed image 16 transferred onto paper 14
The color-erased toner image 15 on the back side is erased at the time of fixing. That is, as shown in FIG. 4, the paper 14 having the unfixed image 16 formed by the image forming device on the front surface and the fixed decoloring toner image 15 on the back surface is the fixing roller 9 and the pressure roller 1 of the fixing device.
When it is carried into the 0 pressure contact part (nip part), the unfixed image 16
Is heated and pressed to fix it on the paper. Then, the heated paper 14 having the fixed image on the front surface and the fixed image 15 of the decoloring toner on the back surface is carried into the pressure contact portion (nip portion) between the fixing roller 9 and the light transmitting roller 3. At this time, the back surface of the sufficiently heated sheet 14 is irradiated with a predetermined light by the color erasing lamp 1, and the image 15 of the color erasing toner is erased.

(7) Decoloring Operation of Printer Equipped with Decoloring Device (Claims 5 and 6) Now, the printer shown in FIG. 1 is an example equipped with the decoloring device having the configuration shown in FIG. The following is a description of the operation in the case where the erasing apparatus passes the sheet twice by the conveying mechanism and then conveys it to the printer section to form an image. 1 and 2,
The sheet 14 is fed to the erasing device 34 by the sheet feeding roller 27 from the trial printing cassette 25 in which the sheet is set with the decoloring toner image side facing up. When it is detected that the paper 14 has entered the erasing device 34, the erasing lamp 1 starts lighting. While being conveyed through the erasing device 34, the paper is heated by the light-transmitting roller 3 and is irradiated with a predetermined light by the erasing lamp 1. Then, the sheets that have completed the first erasing operation are stacked on the intermediate tray 37 by the transport rollers 35,
The erasing device returns to the temporary standby state.

Next, the conveying roller 35 is rotated in the reverse direction so that the sheet is carried into the erasing device 34 again. At this time, since the paper is in a heated state, when the pressure contact of the pressure roller 4 is released by the cam as shown in FIG. 5, the heating stress on the paper is reduced and the occurrence of paper wrinkles can be prevented. Further, as an advantage of releasing the pressure contact, since the paper and the roller do not come into contact with each other, it is not necessary to provide a separation claw on the right side of the roller in FIG. 2, and the apparatus can be downsized. At this time, the erasing lamp 1 continues to be lit, and the second erasing operation is completed, and the image on the paper is sufficiently erased. If the pressure contact is not released, the conveying quality will be slightly deteriorated, but the decoloring effect will be increased.
After the sheet has passed the erasing device 34, the erasing device 34 is in a standby state. The sheet that has passed through the erasing device 34 twice is inverted by the switching claw 36 and is reversed by the registration roller 23 of the printer section.
Be delivered to. Then, the photosensitive drum 20 of the printer unit
The toner image formed above is transferred to the paper by the transfer unit, a new unfixed image is formed on the back surface of the erased surface of the paper, and the unfixed image is fixed by the fixing device 31, and the discharge tray 3
3 is ejected on top. As described above, in the image forming apparatus shown in FIG. 1, since the erasing device having the heating means and the light irradiating means passes the paper twice to perform the erasing process, the image is conveyed to the printer section. Even if the color speed (conveying speed of the erasing device) is set to be about the same as the conveying speed on the printer side, the erasing can be surely performed.

The example of the operation described above is the erasing device 34.
2 is an example of the configuration shown in FIG. 2, but the same operation is performed when the erasing device 34 has the configuration shown in FIG.
Further, when the fixing device also serving as the erasing device shown in FIG. 4 is used, fixing and erasing can be performed at the same time as described above, so that the erasing device 34, the intermediate tray 37, etc. of FIG. It is not necessary, the size of the device can be reduced, and the operation becomes simple.

[0025]

As described above, in the image forming apparatus according to the first and second aspects, since the erasing means is provided with the heating means and the light irradiating means, the erasing property of the erasing toner is improved. Improved (improvement of erasing speed), and erasing can be surely performed even if the erasing speed is adjusted to the conveyance speed of the image forming section side.
An image forming apparatus integrated with a decoloring device can be easily realized.

In the image forming apparatus according to the third aspect of the present invention, since the member which integrates the heating unit and the light irradiating unit is used as the erasing unit, the erasing unit can be downsized and the erasing unit is built in. The size of the image forming apparatus can be reduced.

In the image forming apparatus of the fourth aspect, since the heating means of the erasing device is common to the fixing device of the image forming device, only the light irradiating means may be added as the erasing device. Further miniaturization becomes possible. Further, fixing and erasing can be performed at the same time, and the processing speed can be improved.

In the image forming apparatus of the fifth aspect, since the sheet is conveyed to the image forming section after passing through the erasing means a plurality of times, the erasing speed is improved and the erasing can be performed more reliably. An image forming apparatus integrated with a decoloring device can be easily realized.

In the image forming apparatus of claim 6, the erasing means performs heating and light irradiation in the first erasing operation,
Since only light irradiation is performed in the second and subsequent color erasing operations, the heating stress on the paper is minimized, so curling is reduced and paper wrinkling can be prevented. Further, as an advantage of releasing the pressure contact, the sheet and the roller do not come into contact with each other at the time of erasing the color after the second time, so that it is not necessary to provide a separation claw on the downstream side of the transport path after the second time, and the apparatus can be downsized. .

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, and is a schematic configuration diagram of an image forming apparatus integrally provided with an image forming unit (laser printer) using a laser and an erasing unit.

FIG. 2 is a schematic configuration diagram of an erasing device showing one embodiment of claims 1 and 3.

FIG. 3 is a schematic configuration diagram of an erasing device showing an embodiment of claims 1 and 2.

FIG. 4 is a diagram showing one embodiment of claims 1 and 4, and is a schematic configuration diagram showing a configuration example of a heat fixing device which also serves as a heat roller fixing device and a erasing device.

FIG. 5 is an explanatory view of a roller pressure contact releasing mechanism showing an embodiment of claims 5 and 6;

FIG. 6 is a diagram showing a toner erasing speed (erasing device carrying speed) in an erasing device using a heating member and a 600 W halogen lamp (erasing lamp).

[Explanation of symbols]

1: Decoloring lamp 2: Reflector 3: Light-transmitting roller 4: Pressure roller 5: Separation claw 7: Cleaning roller 8: Halogen lamp heater 9: Fixing roller 10: Pressure roller 11: Oil application roller 12: Separation Nail 13: Heating roller 14: Paper 15: Decolored toner image 16: Unfixed image 17: Laser generator 18: Optical system 19: Reflector 20: Photosensitive drum 21: Charger charger 22: Developing device (22a: Black toner) , 22b: For decoloring toner) 23: Registration roller 24: Paper feeding cassette 25: Cassette for trial printing 26: Paper feeding roller 27: Paper feeding roller 28: Transfer charger 29: Separation charger 30: Conveyor belt 31: Fixing device 32: Cleaning device 33: Ejection tray 34: Decoloring device 35: Conveying roller 36: Switching claw 37: Intermediate tray

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location G03G 15/22 103 Z 6830-2H (72) Inventor Yasuhisa Kato 1-3, Nakamagome, Ota-ku, Tokyo No. 6 in Ricoh Company Ltd. (72) Inventor Keizo Yasuda 1-33 Nakamagome, Ota-ku, Tokyo No. 6 In-Ricoh Company Ltd. (72) Eiji Sawamura 1-33 Nakamagome, Ota-ku, Tokyo No./Ricoh Company (72) Inventor Yoshiyuki Kimura 1-3-6 Nakamagome, Ota-ku, Tokyo ・ Ricoh Company (72) Inventor Genichi Yasui 1-3-6 Nakamagome, Ota-ku, Tokyo・ In Ricoh Co., Ltd. (72) Inventor Masahiko Sato 1-3-6 Nakamagome, Ota-ku, Tokyo ・ In Ricoh Co., Ltd. (72) Inventor Yuzo Kono 1-chome, Nakamagome, Ota-ku, Tokyo No. 3-6 in Ricoh Co., Ltd. (72) Inventor Masami Okamoto 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 in-Ricoh Co., Ltd. (72) Masataka Ehara 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 in Ricoh Co., Ltd.

Claims (6)

[Claims] 1. An image forming apparatus having a toner erasing unit for a sheet on which an image is formed with a erasing toner, wherein the erasing unit comprises a heating member provided in a sheet conveying path and a light irradiating member. An image forming apparatus characterized by the above. 2. An image forming apparatus having a toner erasing means for a sheet on which an image is formed with a erasing toner, wherein the erasing means comprises a heating member containing a heating member, a pressing member in pressure contact with the heating member, and a heating member for heating these members. An image forming apparatus, comprising: a lamp for irradiating a predetermined light onto a conveying surface downstream of a conveying path of the means. 3. An image forming apparatus having a toner erasing means for a paper on which an image is formed with a erasing toner, wherein the erasing means is a heating and light irradiating member which is made of a light transmissive material containing heat generation and a light emitting member. The image forming apparatus is characterized in that the heat-generating and light-emitting members are surrounded by a reflection plate that collects light after the pressure-contacting portion or the conveying path thereof. 4. An image forming apparatus having a toner erasing unit for a sheet on which an image is formed with a erasing toner, wherein the erasing unit comprises a fixing roller having a heat generating member and a pressure roller in pressure contact with the fixing roller. An image forming apparatus comprising: a fixing roller, and a color erasing roller made of a light-transmissive material having a light-emitting member built-in, in pressure contact with the pressure roller at a downstream side of a conveying path. 5. An image forming apparatus having a toner erasing means for a sheet on which an image is formed with an erasing toner, wherein the erasing means is located upstream of a conveying path from an image forming section of the image forming apparatus, and the sheet is An image forming apparatus, which passes through the erasing means at least twice or more before reaching the image forming means. 6. The image forming apparatus according to claim 5, wherein when passing through the erasing means for the first time, the heating member and the light irradiating member are passed, and during passing for the second time and thereafter, only the light irradiating member is passed. An image forming apparatus characterized by.