JPH0720666A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain excellent image quality even when a transfer material on which an image is formed by using decolorizing toner, is repetitively used several times. CONSTITUTION:The adhered amount of the decolorized decolorizing toner on both sides of the transfer paper supplied to an image forming part is detected by photosensors 12 and 13. When an upper surface in a paper supply cassette 6 is decided as a copying surface having the less adhered amount of toner based on output voltage alpha and beta from the photosensors, the transfer paper is fed to the image forming part from the cassette 6 as it is. When the lower surface in the cassette 6 is decided as the copying surface, the transfer paper is fed to the image forming part after the surface of the transfer paper is reversed by a reverse unit 14. In the case the output voltage is smaller than a reference value, it is good to house the transfer paper in a discarded cassette 16 or to perform development with ordinary toner, after inhibiting the copying operation. It is acceptable to change a transfer current in accordance with the output voltage. It is also acceptable to house the transfer paper in an intermediate cassette 17 in advance so that the copying surface may be the upper surface.

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 such as a copying machine, a facsimile or a printer, and more specifically, it contains a transfer material having decolorizable toner decolorized by a predetermined method. The present invention relates to an image forming apparatus including a transfer material storage unit for performing the image formation and an image forming unit that forms an image on the transfer material.

[0002]

2. Description of the Related Art Recently, it has been pointed out that the amount of paper dust from offices and the like is remarkably increasing, as ecology is being called for.
On the other hand, although the use of recycled paper is increasing for the purpose of resource saving, using recycled paper cannot reduce the amount of paper dust. Therefore, in recent years, an image is formed on a transfer paper as a transfer material by using a decolorizable toner, and after use, for example, light having a specific decolorizing wavelength is irradiated to decolor the decolorizable toner, and the transfer is performed. A method has been proposed in which paper is reused many times, and this method is being used to reduce the amount of paper dust.

[0003]

By repeating the transfer of the toner image onto the transfer material by the decolorizable toner and the decolorization of the decolorizable toner many times, the decoloration on the transfer material becomes possible. Since the total amount of adhered toner increases, transfer defects and fixing defects are likely to occur, and the image quality may significantly deteriorate. The occurrence of this transfer failure and fixing failure is
This can also be determined by knowing the number of times the toner image is transferred to the transfer material by the decolorizable toner and the decolorable toner is erased. However, when the transfer material is repeatedly used, it has been difficult to determine which surface has been used and how many times it has been used after both surfaces are used. Further, the guaranteed number of times of use by the manufacturer is also the number of times of single-sided use, which is stricter than it actually is. Also on the user side, after the transfer material is used on both sides, the amount of toner that can be erased is large,
That is, it is often used in terms of poor image quality.

The present invention has been made in view of the above problems, and it is an object of the present invention to use a transfer material on which an image is formed using a color erasable toner, which is repeatedly used. An object of the present invention is to provide an image forming apparatus capable of obtaining good image quality.

[0005]

In order to achieve the above object, the invention of claim 1 is a transfer for accommodating a transfer material to which a decolorizable toner decolorized by a predetermined method is attached. An image forming apparatus including a material storage portion and an image forming portion for forming an image on the transfer material is provided with a toner adhesion amount detection means for detecting the adhesion amount of the decolorizable toner on the transfer material. It is characterized by. Here, the decolorizable toner can be decolored by, for example, a method of irradiating light, a method of heating, or the like.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the toner adhesion amount detecting means is configured to detect the adhesion amount of the decolorizable toner on both surfaces of the transfer material, It is characterized in that a transfer surface setting means for setting a transfer surface on which an image is transferred is provided based on the detection result of the toner adhesion amount detecting means.

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, a transfer material conveying means for conveying the transfer material to the transfer material accommodating portion is provided so that the transfer surface is aligned in a predetermined direction. It is characterized by that.

According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, there is provided control means for prohibiting the image forming operation when the amount of toner adhering detected by the toner adhering amount detecting means is larger than a predetermined amount. It is characterized by that.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, the transfer material container different from the transfer material container, and the amount of adhesion detected by the toner adhesion amount detecting means is a predetermined amount. In the case where the number of the transfer materials is larger, the transfer material transfer means for transferring the transfer material, the amount of which has been detected, to the other transfer material storage portion is provided.

According to a sixth aspect of the present invention, any one of the first developing device using the decolorizable toner, the second developing device using the toner of a color different from the decolorizable toner, and the developing device is provided. When the developing device setting means for setting one to be used and the adhesion amount detected by the toner adhesion amount detecting means are larger than a predetermined amount, the second device is set regardless of the setting of the developing device by the developing device setting means. And a control means for controlling to perform development using the developing device. Here, the developing device setting means may be configured, for example, so that the user can select and set it, or the device main body automatically selects and sets the first developing device. You can

According to a seventh aspect of the invention, in the image forming apparatus according to the first aspect, there is provided control means for changing the image forming process condition based on the detection result of the toner adhesion amount detecting means. To do.

[0012]

According to the present invention, the toner adhesion amount detecting means detects the adhesion amount of the decolorizable toner on the transfer material to which the decolorizable toner decolorized by a predetermined method is attached. From this detection result, it is possible to know the surface of the transfer material to which the decolorizable toner is less attached.

Further, in the invention of claim 2, the toner adhesion amount detecting means detects the adhesion amount of the decolorizable toner on both surfaces of the transfer material, and the transfer surface setting means detects the toner adhesion amount. By setting the transfer surface on which the image is transferred based on the detection result of the means, it becomes possible to automatically set the surface having a small amount of the decolorizable toner attached as the transfer surface.

According to the third aspect of the present invention, the transfer material conveying means conveys and stores the transfer material in the transfer material accommodating portion so that the transfer surfaces are aligned in a predetermined direction.
The transfer material can be stored in advance in the transfer material storage unit so that the surface of the transfer material having a small amount of decolorizable toner attached thereto becomes the transfer surface.

Further, in the invention of claim 4, the control means controls the image forming operation to be prohibited when the adhesion amount detected by the toner adhesion amount detecting means is larger than a predetermined amount. It is possible to prevent the toner image of the erasable toner from being transferred to the surface of the transfer material on which the amount of the erasable toner that exceeds the predetermined amount adheres.

Further, in the invention of claim 5, the transfer material is separated from the transfer material accommodating portion when the amount of adhesion detected by the toner adhesion amount detecting means by the transfer material conveying means is larger than a predetermined amount. By transporting and storing the transfer material in the transfer material storage portion, the transfer material in which the decolorizable toner in an amount exceeding the predetermined amount adheres to the transfer surface on which the image is transferred is used by the user. The transfer material can be accommodated in another transfer material accommodating portion that can be operated from outside the apparatus.

According to a sixth aspect of the invention, in the developing device setting means, the first developing device uses a decolorizable toner, and the second developing device uses a toner of a color different from the decolorizable toner. Set to use either one of. Then, when the adhesion amount detected by the toner adhesion amount detection unit by the control unit is larger than a predetermined amount, the development is performed using the second developing device regardless of the setting of the developing device by the developing device setting unit. By performing control so that the toner image having a color different from that of the color erasable toner can be transferred onto the surface of the transfer material on which the amount of color erasable toner exceeding the predetermined amount adheres.

Further, in the invention of claim 7, the control means controls so as to change the image forming process condition based on the detection result of the toner adhesion amount detection means, thereby erasing on the transfer material. It becomes possible to change the image forming process conditions such as the transfer condition and the fixing condition according to the amount of adhered colored erasable toner, and set the image forming process condition suitable for the transfer surface of the transfer material. .

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter referred to as a copying machine) which is an image forming apparatus will be described below. FIG. 1 is a front view showing a schematic configuration of a copying machine according to this embodiment. The image forming unit of the copying machine includes a photoconductor drum 1 having a photoconductor, which is an image carrier, on the surface thereof.
The charging charger 2, an exposure device (not shown), a developing unit 4 which is a developing device using decolorizable toner, a transfer / separation device 5, and the like. Here, as the decolorizable toner, for example, a toner that can be decolorized by a method of irradiating light, a method of heating, or the like can be used. The photoconductor drum 1 is uniformly charged by the charging charger 2 while rotating in the arrow direction. An optical image 3 corresponding to image information is exposed by the exposure device on the uniformly charged photosensitive drum 1 to form an electrostatic latent image. This electrostatic latent image is developed by the developing unit 4 and becomes a toner image with decolorizable toner. This toner image is transferred
A sheet feeding cassette 6 serving as a transfer material storage unit by the separating device 5.
The image is transferred to a transfer paper (not shown) as a transfer material supplied from. The transfer paper on which the toner image is transferred is separated from the surface of the photosensitive drum 1, fixed by the fixing roller 7 and the pressure roller 8 of the fixing device, and discharged onto the paper discharge tray 9. The toner remaining on the photosensitive drum 1 without being transferred is cleaned by the cleaning device 10, and the residual charge is removed by the charge removing device (not shown) to prepare for the next copying operation.

By repeating the transfer of the toner image onto the transfer paper with the erasable toner and the erasing of the erasable toner many times, the total amount of the erasable toner deposited on the transfer paper increases. As a result, defective transfer or defective fixing is likely to occur, and the image quality may be significantly deteriorated.

Therefore, in this embodiment, the toner adhesion amount detecting means detects the adhesion amount of the erasable toner on the transfer paper, and controls the image forming process based on the detection result. As the toner adhesion amount detecting means, the surface on the transfer paper on the paper feed cassette 6 (hereinafter, this surface is referred to as surface A)
Photosensor 1 for detecting the amount of toner that can be erased
2, and the photosensor 13 that detects the amount of decolorizable toner attached to the other surface of the transfer paper, that is, the lower surface of the paper feed cassette 6 (hereinafter, this surface is referred to as the B surface). It is provided on the road 11. This photo sensor 12, 13
Irradiates the transfer paper with light and detects the intensity of the reflected light. When the decolorizable toner that has been decolorized adheres to the transfer paper, the thickness of the decolorizable toner layer increases, and the intensity of reflected light decreases. Therefore, when the amount of toner that can be erased increases, the output voltage of the photosensors 12 and 13 decreases.

Further, in this embodiment, the transfer surface setting means for setting the transfer surface for transferring an image, that is, the copy surface, requires the reversing unit 14 for switching back the transfer paper and reversing the copy surface, and the transfer paper. The transport path switching unit 15 for loading / unloading the reversing unit 14 in accordance with the above, a control unit 20 described later, and the like. This transport path switching unit 1
5 is also configured so that it can be used as a part of a transfer material transporting means for transporting an unusable transfer paper to a waste cassette 16 which is a transfer material storage portion different from the paper feed cassette 6.

FIG. 2 is a schematic configuration diagram of a specific example of the transport path switching unit 15. In a specific example of the transport path switching unit 15, a guide member 15 that is long in the width direction of the transfer sheet and has a triangular prism shape in section.
1, 152, the slopes of the reversing unit 14 side and the discard cassette 16 side are, for example, arcuate concave surfaces so that the transfer paper can be smoothly transported. Also,
The guide members 151 and 152 are configured to be movable left and right and up and down, and are driven by a drive unit such as a solenoid. Then, when the side A is set as the copy side and the transfer paper from the paper feed cassette 6 is directly conveyed to the image forming section, the transfer paper passes between both guide members and is indicated by an arrow C. Be transported. When the transfer paper from the paper feed cassette 6 is conveyed to the reversing unit 14 with the above-mentioned side B set as the copy surface, the transfer path switching unit 15 is moved to the upper right, so that the transfer paper is indicated by the arrow. It is conveyed in the D direction. When the transfer paper from the reversing unit 14 is conveyed to the image forming unit, the transfer paper is conveyed in the direction of arrow E by moving the conveyance path switching unit 15 to the lower right. When the transfer paper from the paper feed cassette 6 is conveyed to the discard cassette 16, the transfer paper is conveyed in the direction of arrow F by moving the conveyance path switching unit 15 to the left.

FIG. 3 is a block diagram of a control system of the image forming process according to this embodiment. The control unit 20 can be configured by a microcomputer or the like, and for example, as shown in the figure, a CPU
21, a ROM 22, a RAM 23, an I / O unit 24, and the like, and the CPU 21 via the I / O unit 24, the photosensors 12 and 13, the drive unit of the transport path switching unit 15, the drive unit of the developing unit 4, and the like. It is connected to the.

FIG. 4 is an example of a part of a flow chart of the control of the image forming process using the decolorizable toner according to this embodiment. First, when the decolorizable toner is used, the developing unit 4 having the decolorizable toner is selected (step 1). It should be noted that the paper cassette 6 is set with transfer paper that has been used several times. Next, when the copy start button is pressed, the adhered amount of the decolorizable toner on the A and B sides of the transfer paper supplied from the paper feed cassette 6 to the conveyance path 11 is detected by the photo sensor 12, The output voltage is detected at 13, and the output voltage is input to the control unit 20 as an α value and a β value, respectively (steps 2 to 4). Next, the control unit 20 calculates the ratio α / β between the α value and the β value, and determines whether or not the ratio α / β is greater than 1 (step 5). When the value of the ratio α / β is larger than 1, that is, when the toner adhesion amount on the A side is small, the A side is set as the copy surface and the transfer sheet is directly supplied to the image forming unit. On the other hand, when the value of the ratio α / β is 1 or less, the B side is set as the copy side, the transfer sheet is conveyed to the reversing unit 14, is reversed by the switchback, and is supplied to the image forming unit (step. 5-8).

The case where the side A is set as the copy side will be described below. Here, when the B side is set as the copy side, the value of β is used instead of α. When the value of α is smaller than the reference value K _1, it is determined that the decolorizable toner adheres to the A side of the transfer paper as the image quality deteriorates, and the copying machine is set to the copy prohibited state. The transfer paper is conveyed to the waste cassette 16 and accommodated (steps 9 to 11).
On the other hand, when the value of α is equal to or greater than the reference value K ₁ , the image process condition, for example, the transfer current of the transfer / separation device 5 is changed according to the value of α (steps 12 to 18). For example, α
When the value of is in the range of K ₂ or more and less than K ₃ , the transfer current is set to L3.

As described above, according to this embodiment, the photo sensor 1
2 and 13 detect the amount of decolorized toner that can be erased on both sides of the transfer paper supplied to the image forming unit, and the output voltages α and β of the photosensors 12 and 13 erase the transfer paper. It is possible to know the surface with a small amount of colorable toner attached. Therefore, it becomes possible to repeatedly use the transfer paper on the surface in which there is no image quality deterioration such as transfer failure or fixing failure.
When the control means 20 determines the copy surface by the ratio α / β of the output voltage, and when the A surface is determined as the copy surface, the transfer paper is directly transferred from the paper feed cassette 6 to the transfer position of the image forming unit. When the surface B is determined to be the copy surface, the surface of the transfer paper from the paper feed cassette 6 is reversed by the reversing unit 14, and then the paper is switched to the transfer position of the image forming unit. Since the unit 15 and the conveyance rollers are controlled, it is not necessary for the user to confirm the surface of the transfer paper on which the amount of decolorizable toner is attached and set it as the transfer surface.

Further, according to this embodiment, when the detection result of the amount of adhered decolorizable toner on the surface set as the copy surface is larger than a predetermined reference value, that is, the value of α or β is the reference value K. _When it is less than ₁ , the copy operation is controlled to be prohibited, so that the toner image of the erasable toner is not transferred to the transfer paper surface on which the amount of the erasable toner that exceeds the predetermined amount adheres. can do. Therefore,
It is possible to prevent a copy operation that causes image quality deterioration such as transfer failure or fixing failure.

Further, according to the present embodiment, when the detection result of the adhered amount of the erasable toner on the surface set as the copy surface is larger than a predetermined reference value, that is, the value of α or β is the reference value K. _When it is smaller than ₁ , the transfer paper is conveyed to the disposal cassette 16 which can be operated by the user from the outside of the apparatus without using the transfer paper for copying. Therefore, it is possible to prevent the copy operation that causes the image quality deterioration such as the transfer failure or the fixing failure, and the user can easily take out the transfer-prohibited transfer paper from the disposal cassette 16 and discard it.

Further, according to the present embodiment, the transfer / separation device 5 according to the detection result of the adhered amount of the erasable toner on the surface set as the copy surface, that is, the value of α or β,
Since the transfer current is changed, it is possible to prevent transfer defects on the copy surface of the transfer paper, and to reuse the transfer paper many times while maintaining high image quality.

In the above embodiment, after the copy surface of the transfer paper is determined, the copy paper is used as it is or after being reversed by the reversing unit 14 and conveyed to the image forming section for copying. An intermediate cassette 17 may be provided as a storage unit, and after the copy surface of the transfer paper is determined, a transfer material transporting unit that transports and stores the intermediate surface of the intermediate cassette 17 with the copy surface facing upward may be provided. For example, as shown in FIG. 1, the transfer material transporting means includes a transport path switching section 18 similar to the transport path switching section 15, the reversing unit 14, and the control section 2.
0, etc., and when the B side of the transfer paper (the lower surface on the paper feed cassette 6) is determined to be the copy surface, the transfer paper is directly fed from the paper feed cassette 6 via the conveyance path switching unit 18. The intermediate sheet 17 is conveyed and accommodated in the intermediate cassette 17, while the transfer sheet A
When the surface (upper surface on the paper feed cassette 6) is determined to be the copy surface, the controller 20 controls so that the surface is reversed by the reversing unit 14 and then conveyed to the intermediate cassette 17 and accommodated therein. In the case of such a configuration, the transfer paper can be stored in the intermediate cassette 17 in advance so that the copy surface faces up. Therefore, it is necessary to detect the toner adhesion amount on the transfer paper during copying. Is eliminated, and only the normal copy time is needed. Here, the transfer paper whose copy surface has been determined may be conveyed to the intermediate cassette 17 and stored therein as described above, but may be configured to be returned to the paper feed cassette 6. Particularly, in the case of a paper feed cassette that supplies the transfer paper from the lower side of the cassette, the transfer paper may be returned to the upper side of the paper feed cassette.

In the above embodiment, when the detection result of the amount of the decolorizable toner attached on the copy surface is larger than the predetermined amount, that is, the value of α or β is the reference value K.
_{When the value is} smaller than _1, copy prohibition control is performed to prohibit the copy operation. However, as shown in FIG. 1, a color erasable toner (for example, blue) and a normal toner (for example, black) having a different color are used. The developing unit 19 to be used may be provided, and the control unit 20 may control the development by the developing unit 19 in addition to or instead of the copy inhibition control. For example, by the developing device setting means configured by the control unit 20 or the like, the priority mode is set so that the developing unit 4 for the decolorizable toner develops, or the developing unit 4 for the decolorable toner is selected by the user.
If the detection result of the amount of adhered decolorizable toner on the copy surface is larger than a predetermined amount, that is, the value of α or β is the reference value K.
_When it is smaller than ₁ , the control unit 20 controls the development unit 19 to perform the development. According to this, from the color of the toner on the transfer paper after copying, it is known that the amount of the erasable toner that exceeds a predetermined amount adheres to the transfer paper or that the use of the erasable toner is prohibited. be able to.

Further, in the control example of FIG. 4 of the above embodiment, the transfer current is changed as the image forming process condition, but instead of this, other transfer conditions, fixing conditions, charging conditions, developing conditions, etc. Other image forming process conditions may be changed.

In the above embodiment, the photosensor 1 utilizing light reflection is used as the toner adhesion amount detecting means.
However, the present invention is not limited to this, and other sensors that electrically or magnetically detect the amount of the decolorizable toner attached to the transfer paper may be used.
Further, the positions where the photosensors 12 and 13 are arranged are as shown in FIG.
Is not limited to the position of, for example, the transport path 11
It may be provided at another position above or in the paper feed cassette 6 or the like.

[0035]

According to the present invention, the decolorizable toner on the transfer material to which the decolorizable toner decolored by the predetermined method by the toner adhesion amount detecting means is attached. The amount of adhesion is detected, and the result of this detection makes it possible to know the surface of the transfer material where the decolorizable toner has a small amount of adhesion. The effect is that transfer paper can be used.

In particular, according to the invention of claim 2, the toner adhesion amount detecting means detects the adhesion amount of the decolorizable toner on both surfaces of the transfer material, and the transfer surface setting means detects the toner adhesion amount. By setting the transfer surface on which the image is transferred based on the detection result of the detection means, it becomes possible to automatically set the surface having a small amount of the decolorizable toner attached as the transfer surface. There is an effect that it is not necessary to confirm a surface having a small amount of decolorizable toner attached and set it as a transfer surface.

According to the third aspect of the present invention, the transfer material conveying means conveys and stores the transfer material in the transfer material accommodating portion so that the transfer surfaces are aligned in a predetermined direction. Since the transfer material can be stored in advance in the transfer material storage portion so that the surface of the material on which the amount of decolorizable toner adheres is the transfer surface, the transfer material on the transfer material can be formed during image formation. There is an effect that it is not necessary to detect the amount of the decolorizable toner attached and only the normal image forming time is required.

Further, according to the invention of claim 4, the control means controls the image forming operation to be prohibited when the adhesion amount detected by the toner adhesion amount detecting means is larger than a predetermined amount. Since it is possible to prevent the toner image of the erasable toner from being transferred to the surface of the transfer material on which the amount of the erasable toner that exceeds the predetermined amount is adhered, image quality deterioration such as transfer failure and fixing failure may occur. There is an effect that it is possible to prevent the image forming operation that occurs.

According to the fifth aspect of the present invention, when the amount of toner adhering detected by the toner adhering amount detecting means by the transfer material conveying means is larger than a predetermined amount, the transfer material is regarded as the transfer material accommodating portion. The transfer material having the decolorizable toner in excess of the predetermined amount adheres to the transfer surface on which the image is transferred by transporting the transfer material to another transfer material storage portion and without using the transfer material for image formation. Can be stored in another transfer material storage unit that can be operated from the outside of the apparatus, so that it is possible to prevent an image forming operation that causes image quality deterioration such as transfer failure or fixing failure, and to erase the image by the user. There is an effect that the transfer paper in which the image formation with the possible toner is prohibited can be easily taken out from the other transfer material storage portion and discarded.

Further, according to the invention of claim 6, in the case where the amount of adhesion detected by the toner adhesion amount detecting means by the control means is larger than a predetermined amount, regardless of the setting of the developing device by the developing device setting means. Instead, by controlling the development using the second developing device, the color of the erasable toner and the color of the erasable toner are adhered to the surface of the transfer material on which the amount of the erasable toner exceeding the predetermined amount is attached. Since it becomes possible to transfer toner images with different toners, it is possible to erase more than the specified amount from the color of the toner on the transfer material after image formation to the transfer surface of the transfer material supplied to the image forming section. There is an effect that the user can know that the toner is attached.

Further, according to the invention of claim 7, the control means controls the image forming process condition to be changed based on the detection result of the toner adhesion amount detecting means. The image forming process conditions such as the transfer condition and the fixing condition can be changed according to the amount of the erased erasable toner adhered, and the image forming process condition suitable for the transfer surface of the transfer material can be set. Therefore, it is possible to prevent image quality deterioration such as transfer failure and fixing failure on the transfer surface of the transfer material, and it is possible to reuse the transfer material many times while maintaining high image quality.

[Brief description of drawings]

FIG. 1 is a front view showing a schematic configuration of a copying machine according to an embodiment.

FIG. 2 is a front view showing a schematic configuration of a transport path switching unit 15 of the copying machine.

FIG. 3 is a block diagram of a control system of an image forming operation using decolorizable toner of the copying machine.

FIG. 4 is a flowchart of control of an image forming operation using the decolorizable toner.

[Explanation of symbols]

 4 Developing Unit (Decolorizable Toner) 5 Transfer / Separation Device 6 Paper Feed Cassette 11 Transfer Paper Conveying Path 12, 13 Photo Sensor 14 Reversing Unit 15, 18 Conveying Path Switching Section 16 Discarding Cassette 17 Intermediate Cassette 19 Developing Unit (Normal Toner) ) 20 control unit

Claims (7)

[Claims] 1. A transfer material accommodating portion for accommodating a transfer material to which decolorizable toner decolorized by a predetermined method is attached,
An image forming apparatus having an image forming unit for forming an image on the transfer material, characterized in that a toner adhesion amount detecting means for detecting an adhesion amount of decolorizable toner on the transfer material is provided. Forming equipment. 2. The toner adhesion amount detection means is configured to detect the adhesion amount of decolorizable toner on both surfaces of the transfer material, and the image is transferred based on the detection result of the toner adhesion amount detection means. The image forming apparatus according to claim 1, further comprising transfer surface setting means for setting a transfer surface to be set. 3. The image forming apparatus according to claim 2, further comprising a transfer material conveying means for conveying the transfer material to a transfer material accommodating portion so that the transfer surface is aligned in a predetermined direction. 4. The image forming apparatus according to claim 1, further comprising control means for prohibiting an image forming operation when the toner adhesion amount detected by the toner adhesion amount detecting means is larger than a predetermined amount. 5. A transfer material accommodating portion different from the transfer material accommodating portion, and when the adhering amount detected by the toner adhering amount detecting means is larger than a predetermined amount, the transfer material having the adhering amount detected is separated from the transfer material accommodating portion. The image forming apparatus according to claim 1, further comprising a transfer material transporting unit that transports the transfer material to a transfer material container. 6. A first developing device using a color erasable toner, a second developing device using a toner of a color different from the color erasable toner, and a setting for using one of the developing devices. And a developing device setting means for controlling the developing device setting means, and when the amount of adhesion detected by the toner adhesion amount detecting means is larger than a predetermined amount, the second developing device is used to develop regardless of the setting of the developing device by the developing device setting means. 2. The image forming apparatus according to claim 1, further comprising: a control unit that controls so as to perform. 7. The image forming apparatus according to claim 1, further comprising control means for changing an image forming process condition based on a detection result of the toner adhesion amount detecting means.