JP2000177907A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove a curl to an optimum level by controlling the operating condition of a curl removing means based on the moisture content information detected by a moisture content detecting means. SOLUTION: A moisture detecting means 1140 detects the moisture content of a recording material fed and conveyed from paper feed cassettes 1110, 1111. When the moisture content of the recording material is small, the curl quantity after fixing is small, thus a step angle (the shift quantity of a pressing roller 2) is reduced, and the pressure of the pressing roller 1 is weakened. As the moisture content of the recording material is increased, the curl quantity becomes larger, thus the step angle is increased in sequence, and the pressure of the pressing roller 1 is strengthened to increase curl correcting force. The pressing roller 1 is set to a proper pressing condition suitable for the moisture content of the recording material. After the operating condition of a curl removing means is set, a normal copy operation is started. When this curl removing control is applied, it is effective to minimize the curl quantity after fixing.

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, and more particularly, to an image forming apparatus provided with a recording material decurling unit.

[0002]

2. Description of the Related Art A conventional image forming apparatus of this type is shown in FIG.
It is configured as shown in FIG. FIG. 2 is a main cross section of a copying machine using an electrophotographic method.

[0003] The image formation of the copying machine 1100 is performed as follows.

An original set on a platen 1101 is read by an optical unit 1102 and scanned, and a lens 110 is scanned.
At 3, an image is formed on the CCD 1104. The optical information on the CCD 1104 is converted into an electric signal and converted into an electric signal.
5 and is converted into a laser beam, and the photosensitive drum 1106
Imaged on top.

A developing unit 1107, a cleaner unit 1108, and the like are provided around the photosensitive drum 1106. The latent image on the photosensitive drum 1106 is developed with toner, and a recording material is brought into contact with and transferred to the photosensitive drum 1106. Thus, an image is formed. As described above, the image forming unit is configured by the polygon scanner 1105, the photosensitive drum 1106, the developing unit 1107, the cleaner unit 1108 and the like disposed around the photosensitive drum 1106.

On the other hand, recording materials are cassettes 1110 and 1111.
Is fed by a pickup roller 1112 and is fed to a registration roller 1115 by a conveyance roller 1114. Next, after being shifted by a predetermined timing by the registration roller 1115, the image is transferred toward the drum 1106 to transfer the image.

Then, the sheet is conveyed to the fixing device 1121 by the conveying belt 1120, and the image is fixed. Thereafter, the sheet is discharged onto the sheet discharge tray 1122. Image formation is performed in this manner.

This type of image forming apparatus is used in a relatively wide range of environmental conditions from high temperature and high humidity, eg, (30 ° C., 95%) to low temperature, low humidity, eg, (10 ° C., 10%). However, the curl state of the sheet material, which is the recording material discharged under each environmental condition, is different, the discharge stackability and consistency of the sheet material are not constant, and in the worst environment, the curl or curl due to the curl , Such as dropping from the tray, pushing out, and jamming.

That is, normal temperature and normal humidity, for example (20 ° C., 60
%), Even when both the stacking property and the matching property are good, in a high-temperature and high-humidity environment, the discharged sheet material may curl greatly concavely upward, and the above-described problem may occur.

On the other hand, Japanese Unexamined Patent Publication No. Hei 5-309997 proposes to have a curl removing means 1130 for removing the curl and a control means for controlling the operating condition of the curl removing means 1130 according to the environmental conditions. I have.

FIG. 3 is a main cross section of a typical structure of the curl removing means 15 of the conventional example.
It is located downstream of the fixing device 1121 (FIG. 2).

The upper pressing roller 1 made of a material having a relatively low hardness such as urethane foam is used for the chloroprene rubber 70.
The nip 11 is formed by pressing and deforming the pressure lower roller 2 made of a material having a higher hardness than the roller 1 such as °, and the curl is removed by allowing the sheet material to pass therethrough. In this case, since the sheet is bent downward (concave downward), upward curl (concave upward) is corrected.

The pressure lower roller 2 is rotatably attached to a side plate (not shown), and is rotated in a sheet conveying direction (arrow C direction) by a driving means (not shown). The pressure upper roller 1 is driven to rotate by being pressed against the pressure lower roller 2, and is rotatably supported by the auxiliary side plate 4. On the other hand, the auxiliary side plate 4 is swingable about the fulcrum 3 with respect to the side plate, and a fan-shaped gear portion 4a is provided on the side opposite to the fulcrum 3. Sector gear 4a
Gears 5, 6, and 7 are engaged with each other.
Is transmitted to the auxiliary side plate 4. That is, when the pressing motor 8 rotates in the A direction, the auxiliary side plate 4 rotates in the A direction, and therefore, the upper pressing roller 1 moves in the pressing direction.

On the other hand, when the pressing motor 8 rotates in the B direction, the auxiliary side plate 4 rotates in the B direction.
Moves in the direction in which the pressure is weakened.

Sensors 9, 10, and 13 are provided near the upper and lower end surfaces of the auxiliary side plate 4, and are provided with a first pressing position (shown by a solid line), a second pressing position (shown by a two-dot broken line) and their positions. An intermediate third pressure position is detected.

The detection signals from the sensors 9, 10, and 13 are sent to the control unit 12 of the image forming apparatus. The control of pressurization of the pressurizing upper roller 1 is performed by the control unit 1 as curl control means.
2 is performed.

FIG. 3B is a block diagram of the curl removing means. A mode input means 14 such as an operation unit and a sensor and sensors 9, 10, and 13 are connected to the input side. On the other hand, the pressurizing motor 8 is connected to the output side,
Controls the rotation direction and rotation angle.

By the above operation, even when the amount of curl after fixing is different such as high temperature and high humidity and low body temperature and low humidity, the curl is removed according to each environment, and the paper discharge stackability is improved.

[0019]

However, the actual amount of curl depends not only on the printing environment but also on the amount of moisture contained in the recording material at that time. As a specific example, when printing in a high-temperature, high-humidity environment, paper having a large amount of water before printing tends to have a larger curl amount after printing than paper having a small amount of water before printing.

In a conventional apparatus, a temporal change in physical properties of a recording material due to a temporal change in an environment in which the recording material is stored is overlooked. For example, in a case where the atmosphere environment in which the recording material is accommodated suddenly changes from high humidity to low humidity, the apparatus body side determines that the humidity is low, and curl removal control is performed according to the low humidity. .

On the other hand, in the case of the recording material, the water content does not change abruptly, that is, the water does not evaporate more rapidly than the recording material. Even if it changes suddenly, the recording material will
It shows the same physical properties as on the high humidity side. In addition, the change in the water content is different between the upper end, the middle, and the lower end of the contained recording material. Has a gradual change in water content.

Further, even when a recording material that has just been opened from a packaging material or a recording material brought in from a different atmosphere environment is used immediately, the atmosphere environment detected by the apparatus main body and the state of the recording material are not changed. It can happen to be different.

As described above, in the case where the curl removing conditions are set based on the atmosphere environment in which the main body is placed, the curl may be unnecessarily curled or the curl removing amount may be increased. Is too little,
There have been problems such as the occurrence of a paper jam and a poor discharge stackability.

Accordingly, an object of the present invention is to set an amount of curl while monitoring the moisture content of a recording material, thereby performing an optimal curl even in a sudden change in the atmospheric environment, and improving the discharge stackability. It is to provide a good image forming apparatus.

[0025]

According to the present invention, there is provided a curl removing means for removing curl of a recording material and a curl removing control means for controlling operating conditions of the curl removing means. An image forming apparatus comprising: a water amount detecting unit configured to detect a water amount included in the recording material; wherein the curl removing control unit detects the curl removing unit based on the moisture amount information detected by the moisture amount detecting unit. Is characterized by controlling the operating conditions of

In this way, even if the atmosphere environment fluctuates rapidly, the change in the water content of the recording material used can be detected in a timely manner, and the operating conditions of the curl removing means can be set. Paper loading can be realized.

Preferably, the water content detecting means is a detecting means for detecting a water content by measuring absorption of infrared rays or microwaves by water contained in the recording material. The curl removing means presses the recording material against a curved surface curved in a direction opposite to the curl of the recording material, and the operating condition of the curl removing means is a pressing force of the curl removing means on the recording material. Is also good.

The curl removing means cools or heats the recording material to generate a temperature change. The operating condition of the curl removing means is the amount of heat deprived from the recording material or given to the recording material. There may be.

Further, the curl removing means may switch which direction of the curl of the recording material is to be removed, and the operating condition of the curl removing means may be the direction of curl of the recording material.

The apparatus further comprises a thickness detecting means for detecting the thickness of the recording material, wherein the curl removing control means includes information on the moisture content detected by the moisture detecting means and the thickness information detected by the thickness detecting means. The operating condition of the curl removing means may be controlled based on the condition.

As described above, the curl of the recording material can be more optimally suppressed by setting the operating conditions of the curl removing means based on the thickness of the recording material and the information on the amount of water.

The apparatus further comprises an environmental condition detecting means for detecting an environmental condition, wherein the curl removing control means performs the above-mentioned curling based on the water content information detected by the water content detecting means and the environmental condition detected by the environmental condition detecting means. The operating conditions of the curl removing means may be controlled.

As described above, by setting the operating conditions of the curl removing means based on the environmental conditions and the information on the moisture content of the recording material, the curling of the recording material can be more optimally suppressed.

Further, there are provided a thickness detecting means for detecting the thickness of the recording material, and an environmental condition detecting means for detecting an environmental condition.
The curl removal control means is configured to perform the curl removal based on the moisture content information detected by the moisture content detection means, the thickness information detected by the thickness detection means, and the environmental condition detected by the environmental condition detection means. The operating conditions of the means may be controlled.

As described above, by setting the operating conditions of the curl removing means based on the recording material thickness, the environmental conditions, and the information on the moisture content of the recording material, the curling of the recording material can be more optimally suppressed.

The environmental condition may be temperature.

The environmental condition may be humidity.

An image forming means for forming an image on a recording material is provided, wherein the curl removing control means controls the water content information detected by the water content detecting means and an image condition for an image formed by the image forming means. The operating conditions of the curl removing means may be controlled based on the above.

As described above, by setting the operating conditions of the curl removing means by combining the image conditions and the information on the moisture content of the recording material, the curling of the recording material can be suppressed more optimally.

The image forming apparatus further includes an image forming means for forming an image on the recording material, and a thickness detecting means for detecting the thickness of the recording material, wherein the curl removing control means is provided for detecting the moisture detected by the moisture amount detecting means. The operating condition of the curl removing unit may be controlled based on the amount information, the image condition of the image formed by the image forming unit, and the thickness information detected by the thickness detecting unit.

As described above, by setting the operating conditions of the curl removing means based on the image conditions, the thickness of the recording material, and the moisture content information, the curling of the recording material can be more optimally suppressed.

An image forming means for forming an image on a recording material, and an environmental condition detecting means for detecting an environmental condition, wherein the curl removing control means includes the moisture information detected by the moisture detecting means and the image information. The operating condition of the curl removing means may be controlled based on an image condition of an image formed by the forming means and an environmental condition detected by the environmental condition detecting means.

As described above, by setting the operating conditions of the curl removing means based on the image conditions, the environmental conditions, and the information on the moisture content of the recording material, the curling of the recording material can be more optimally suppressed.

The image forming apparatus further comprises an image forming means for forming an image on the recording material, a thickness detecting means for detecting the thickness of the recording material, and an environmental condition detecting means for detecting an environmental condition. Is detected by the moisture information detected by the moisture detecting means, the image condition of the image formed by the image forming means, the thickness information detected by the thickness detecting means, and detected by the environmental condition detecting means. The operating condition of the curl removing means may be controlled based on the environmental condition.

As described above, by setting the operating conditions of the curl removing means based on the image conditions, the environmental conditions, the thickness of the recording material, and the moisture content information, the curling of the recording material can be more optimally suppressed.

The environmental condition may be a temperature.

The environmental condition may be humidity.

The image condition may be an image density.

The image condition may be an image density.

The image condition may be the number of developed colors.

Also, a single-sided image forming mode for forming an image on one side of a recording material through a predetermined image forming process, and a double-sided image forming mode for forming an image on the back side of the recording material through the image forming process And at least one of multiple image forming modes of a multiple image forming mode for forming multiple images on one side of the recording material by repeating the image forming process on the same surface, and the curl removing control unit includes The curl removing means may be controlled according to the image forming mode.

In this way, it is possible to perform the curl removal suitable for each image forming mode in accordance with the change in the curl amount caused by the difference between the image forming modes.

[0053]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

(First Embodiment) This embodiment will be described below with reference to FIGS. Curl removing roller (curling removing means) including upper pressing roller 1 and lower pressing roller 2
The basic operation is the same as that of the conventional example shown in FIG. 3, and therefore detailed description is omitted. Here, the detection of the water content of the recording material and the control of the curl removing means will be described in detail.

FIG. 1 is a main cross section of an electrophotographic copying machine showing the structure of the image forming apparatus of the present invention.

In this apparatus, in addition to the conventional structure, a water amount detecting means 1140 is arranged to detect the water amount of the recording material fed and conveyed from the paper feed cassettes 1110 and 1111 containing the recording material. This information is stored in storage means or memory 114.
1 is stored.

FIG. 4A is a flowchart, and FIG.
Is a table for determining the step angle n of the pressurizing motor 8 in FIG. 3 from the output of the memory 1141 in which the moisture content information is stored, and is stored in the memory of the control unit 12 as the curl removing control means.

The operation is started by pressing a copy start button (not shown). In step 1, an operation of returning the pressure upper roller 1 to the home position (two-dot chain line) is performed. Sensor 10
Is checked, and if it is ON, the process proceeds to the next step. If it is not ON, the pressurizing stepping motor 8 is rotated in the direction B, and when the auxiliary side plate 4 crosses the sensor 10, it stops. Thus, the movement of the pressure upper roller 1 to the home position is completed (step 1).

Next, in step 2, the step angle of the pressure motor 8 (movement amount of the pressure roller 2) is determined. FIG. 4B shows the relationship between the amount of water and the step angle of the pressurizing motor 8. Then, it is determined that the step angle is n1 when the water content of the recording material is m1%, and is n2 when the water content of the recording material is m2%. FIG. 4 (b)
As shown in the table, the table has an upward-sloping shape, and when the moisture content of the recording material is small, the curl amount after fixing is small. Therefore, the step angle is reduced and the pressure on the pressure roller 1 is reduced. Since the curl amount increases as the water content of the recording material increases, the step angle is gradually increased to increase the pressure of the upper pressing roller 1 and increase the curl correcting force.

As described above, when the step angle of the pressure motor 8 is determined from the output of the memory 1141 in which the water content information is stored in step 2, the upper roller 1 is moved in step 3. Then, the pressure motor 8 is rotated in the direction A until the step angle n determined in step 2 is reached, and stopped.
Thereby, the upper pressing roller 1 is set to an appropriate pressing condition suitable for the water content of the recording material. When the condition setting of the curl removing means is completed, a normal copying operation is started.

The water content detecting means 1140 as a means for detecting the water content of the recording material can be one which can be detected in a short time.
That is, a material that detects absorption of infrared rays, microwaves, and the like by moisture contained in the recording material is desirable.

The position of the water content detecting means 1140 is
In the present embodiment, the recording material is installed in the sheet feeding and transporting portion, and the amount of moisture of the recording material passing therethrough is measured. The moisture content of the recording material in the loaded state may be measured.

The position of the curl removing roller is as follows.
It is not limited to the downstream of the fixing device, and may be immediately after paper feeding or immediately before transfer.

Further, in a configuration in which the recording material is carried on the recording material holding means by electrostatic attraction or the like and the visible image is transferred onto the recording material, the recording material is carried on the recording material holding means. There is an optimal amount of curl.

For example, in a configuration in which the recording material carrying means is cylindrical, and the recording material is wound around the circumference to perform the transfer, it is necessary that the curvature of the recording material carrying means and the curvature of the recording medium be substantially the same. It is most advantageous to carry a recording medium. Even when curling is performed before the recording material is carried on the recording material carrying means, the curl removal control of the present invention is effective in minimizing the curl amount after fixing.

(Second Embodiment) In the present embodiment, the first
An image forming apparatus including a thickness detecting unit for detecting the thickness of a recording material in addition to the configuration of the embodiment will be described.

In the first embodiment, the curl removal amount is set based on the moisture content information of the recording material. However, the curl amount after fixing of the recording material is large not only in the moisture content of the recording material but also in the thickness of the recording material. Have a correlation. The amount of curl given to the recording material by the curl removing roller differs depending on the thickness of the recording material.

Therefore, in order to perform curl removal more accurately and to realize a reliable discharge stackability, information on the thickness of the recording material is also taken in at the same time, and the information on the thickness of the recording material is integrated with the information on the water content of the recording material. It is desirable to control the decurling rollers.

Further, the value indicated by the water content detecting means for detecting the water content of the recording material by the absorption of light by the water contained in the recording material is influenced by the thickness of the recording material. In order to achieve this, it is desirable that the information on the paper thickness is fed back to the water content detection means so that the water content can be accurately detected for various types of recording materials.

FIG. 5 is a main cross section of an electrophotographic copying machine showing the structure of the image forming apparatus of the present invention.

In this apparatus, a paper thickness detecting means 1150 as a thickness detecting means is arranged in addition to the structure of the first embodiment.
The thickness of the recording material fed and conveyed from the sheet cassettes 1110 and 1111 containing the recording material is detected.

The recording material thickness detecting means 1150 is provided in FIG.
As shown in FIG. 7, a registration roller 319 is supported by a shaft, and a registration roller 320 that can be moved up and down is held by the registration roller 319 by a spring 321 from above. When recording materials having different thicknesses pass between the two registration rollers 319 and 320, the registration rollers 320
Is transmitted to the potentiometer 323 by the clutch 322 and the thickness of the recording material is detected.

In general, the stiffness of a recording material is stronger for a recording material having a larger thickness. Curling is caused by the difference in front and back of fiber expansion and contraction due to toner cohesion and moisture absorption of the recording material, but when the thickness of the recording material is large, the stiffness of the recording material is stronger even if these forces are large. , No curling. Therefore, by detecting the thickness of the recording material, particularly in the case of a recording material having a small thickness, the curl removing roller is controlled so as to increase the curl removing amount already determined by the moisture content detection. In the case of a thick recording material, the curl removing roller is controlled so as to weaken the curl removing. By performing such control, even in the case of recording materials having different thicknesses, the recording material becomes straight on the paper discharge tray 1122, and it becomes possible to stably discharge paper.

As a method of detecting the paper thickness, if the type of paper to be passed can be determined based on the type of the paper feed cassette of the selected paper feeder, such as a cassette for thick paper, this signal is detected. It is also possible to substitute it as a means.

Of course, the paper thickness detecting means is not limited to the detecting means having the above-described structure, and any suitable means can be selected.

In the case where the accurate judgment is insufficient or impossible by the detecting means having the above-described structure, the detecting means may be replaced by the detecting means having the above-described structure or may be replaced by the operator. Can manually input such a signal to the control device of each device.

(Third Embodiment) In the present embodiment, the first
An image forming apparatus including an environment detecting unit that detects the temperature and humidity of a printing environment in addition to the configuration of the embodiment will be described.

In the first embodiment, the curl removal amount is set based on the moisture content information of the recording material. However, the curl amount after fixing of the recording material depends not only on the moisture content of the recording material but also on the temperature and humidity of the printing environment. Is also affected.

Therefore, in order to perform the curl removal more accurately and to realize a reliable discharge stacking property, the information of the printing environment is also taken in at the same time, and the curl removal amount is integrated with the information of the water content of the recording material. And it is desirable to control the decurling roller.

FIG. 7 is a sectional view of the present embodiment, in which an environmental condition detecting means 1160 for detecting the use environment of the image forming apparatus is installed at a required position in the main body. Here, the environmental condition detecting means 1160 is a temperature detecting means. Environmental condition detecting means 11
The temperature detected by 60 is output as a voltage and sent to the controller 12 of the curl removing roller.

FIG. 8A shows the relationship between the output voltage of the environmental condition detecting means 1160 and the temperature. For example, when the output voltage of the environmental condition detecting means 1160 is V1, the temperature is t1 ° C., and when the output voltage is V2, the temperature is t2 ° C. FIG. 8B shows the relationship between the temperature and the step angle of the pressurizing motor 8 when a curl is removed after printing when a recording material having a certain water content is printed. That is, it is determined that the step angle is n1 when the temperature is t1 ° C. and n2 when the temperature is t2 ° C. FIG. 8B
As shown in (1), since the table has a concave shape and the curl amount is small near normal temperature, the step angle is reduced to weaken the pressure of the pressure roller 2, and the curl amount increases as the temperature becomes low and high. Therefore, the step angle is gradually increased to increase the pressure of the pressure roller 2 to increase the curl correcting force.

As described above, several tables such as those described above are provided for each water content level of the recording material, and these are stored in the control unit 12 of the decurling roller. By determining and controlling the curl removal amount from both of the above conditions, more optimal curl removal can be performed.

Here, an example in which a sensor is used to detect the environmental condition has been described. However, an input may be made from the operation unit of the image forming apparatus.

Alternatively, both the temperature and the humidity may be detected, and based on the information, the absolute humidity or the like may be calculated to control the curl removing means.

As described above, by reflecting the environmental data in addition to the moisture content of the recording material in the control of the curl removal, a more stable discharge stacking becomes possible.

(Fourth Embodiment) In the present embodiment, the first
In addition to the configuration of the embodiment, an image forming apparatus that controls operating conditions of a curl removing unit based on image conditions transferred to a recording material will be described.

In the first embodiment, the curl removal amount is set based on the moisture content information of the recording material. However, the curl amount after fixing of the recording material is transferred not only to the moisture content of the recording material but also to the recording material. It is greatly affected by image conditions.

Therefore, in order to perform curl removal more accurately and to realize a reliable discharge stacking property, information on image conditions to be transferred to the recording material is also taken in, and this and information on the moisture content of the recording material are taken into account. It is desirable to define the curl removal amount in total and control the curl removal roller.

FIG. 9 is a block diagram. On the input side, a memory 1141 storing moisture content information and image density data from a reader unit (not shown) are connected.

Generally, the curl after printing of a recording material increases as the image density increases. Since the curl is caused by the difference in front and back of the expansion and contraction of the fiber due to the cohesive force of the toner and the moisture absorption of the recording material, the concave curl increases when the amount of toner is large. Therefore, even when the moisture content of the recording material is the same, when the image density is high, the curl removing roller is controlled so as to enhance the curl removal, and when the image density is low, the curl removing roller is controlled. Is controlled so as to reduce curling.

As described above, by controlling to reflect the information on the print image density in addition to the information on the water content of the recording material, stable discharge stacking is possible even in the case of printing at all image densities.

The image conditions for forming an image are not limited to the set image density, but may be the image density or the number of developed colors.

[0093] These image conditions can also be configured so that the operator can manually input such a signal to the control device of each device.

In the above embodiment, the operating condition of the curl removing means is not limited to the pressing force of the pressure roller, but may be the amount of heat for cooling or heating the sheet material.

The configuration in the above embodiment may be used in an image forming apparatus having a duplex copy mode or a multiple copy mode. That is, when the curl amount of the recording material is small as in the single-sided mode or the double-sided mode, the pressing force of the curl removing unit is reduced. By controlling so as to increase the pressing force, it is possible to perform decurling suitable for the mode.

Further, in the above embodiment, the home position of the pressure upper roller of the curl removing means is in a state of contact with the pressure lower roller with a small force, but the curl removing means is separated by separating the pressure upper roller. The driving load may be reduced as non-operation.

[0097]

As described above, the image forming apparatus according to the present invention comprises a curl removing means for removing curl of a recording material, a curl removing control means for controlling operating conditions of the curl removing means, and a recording apparatus. Since a moisture detecting means for detecting the amount of moisture contained in the material is provided, and the curl removing control means controls the operating condition of the curl removing means based on the moisture amount information detected by the moisture detecting means, the atmosphere Even if the environment fluctuates rapidly, it is possible to set the operating conditions of the curl removing means by detecting a change in the amount of water in the recording material to be used in a timely manner, and to always realize a stable paper discharge stackability.

Further, the apparatus is provided with a thickness detecting means for detecting the thickness of the recording material, an environmental condition detecting means for detecting environmental conditions such as the temperature and humidity of the environment, and the like. By setting the operating conditions of the curl removing means in combination with the above, the curl after printing can be more optimally suppressed.

Further, by controlling the curl removing means according to the image forming mode, it is possible to perform the curl removing suitable for the image forming mode.

[Brief description of the drawings]

FIG. 1 is a main cross-sectional view of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a main cross-sectional view of one embodiment of a conventional image forming apparatus.

FIG. 3A is a main cross-sectional view of a conventional curl removing device, and FIG. 3B is a block diagram of the same device.

FIG. 4A is a flowchart illustrating the operation of the curl removing roller according to the first embodiment of the present invention, and FIG. 4B is a graph illustrating a control table of the apparatus.

FIG. 5 is a main cross-sectional view of an image forming apparatus according to a second embodiment of the present invention.

FIG. 6 is a perspective view of a sheet thickness detecting unit according to a second embodiment of the present invention.

FIG. 7 is a main sectional view of an image forming apparatus according to a third embodiment of the present invention.

FIG. 8 is a graph showing a control table of a decurling roller according to a third embodiment of the present invention.

FIG. 9 is a block diagram of an image forming apparatus according to a fourth embodiment of the present invention.

[Explanation of symbols]

 1106 Image carrier (photosensitive drum) 1107 Developing device 1130 Curl removing unit 1 Upper press roller 2 Lower press roller 1140 Moisture amount detecting unit 1150 Paper thickness detecting unit 1160 Environmental condition detecting unit

Claims (20)

[Claims] 1. An image forming apparatus comprising: a curl removing unit for removing a curl of a recording material; and a curl removing control unit for controlling an operation condition of the curl removing unit. An image forming apparatus, wherein the curl removal control means controls operating conditions of the curl removal means based on the moisture content information detected by the moisture content detection means. 2. The image forming apparatus according to claim 1, wherein said water amount detecting means is a detecting means for detecting an amount of water by measuring absorption of infrared rays or microwaves by water contained in the recording material. apparatus. 3. The curl removing means presses the recording material against a curved surface curved in a direction opposite to the curl of the recording material. The operating condition of the curl removing means is a pressing force of the curl removing means on the recording material. 2. The method according to claim 1, wherein
Or the image forming apparatus according to 2. 4. The curl removing means cools or heats the recording material to generate a temperature change. The operating condition of the curl removing means is the amount of heat deprived from the recording material or given to the recording material. The image forming apparatus according to claim 1, wherein: 5. The method according to claim 1, wherein the curl removing unit is capable of switching which direction of the curl of the recording material is to be removed, and the operating condition of the curl removing unit is a direction of curl of the recording material. Item 3. The image forming apparatus according to Item 1 or 2. 6. A thickness detecting means for detecting a thickness of a recording material, wherein the curl removing control means includes information on a moisture content detected by the moisture detecting means and a thickness detected by the thickness detecting means. The image forming apparatus according to claim 1, wherein an operation condition of the curl removing unit is controlled based on the information. 7. An environment condition detecting means for detecting an environmental condition, wherein the curl removal control means is based on the moisture content information detected by the moisture content detecting means and the environmental condition detected by the environmental condition detecting means. The image forming apparatus according to claim 1, wherein operating conditions of the curl removing unit are controlled. 8. A device according to claim 1, further comprising: a thickness detecting unit configured to detect a thickness of the recording material; and an environmental condition detecting unit configured to detect an environmental condition. The operating condition of the curl removing means is controlled on the basis of the thickness information detected by the thickness detecting means and the environmental condition detected by the environmental condition detecting means. An image forming apparatus according to any one of the above. 9. The image forming apparatus according to claim 7, wherein the environmental condition is temperature. 10. The image forming apparatus according to claim 7, wherein the environmental condition is humidity. 11. An image forming means for forming an image on a recording material, wherein the curl removing control means controls the information on the water content detected by the water content detecting means and the image formed by the image forming means. The image forming apparatus according to claim 1, wherein an operation condition of the curl removing unit is controlled based on an image condition. 12. An image forming means for forming an image on a recording material, and a thickness detecting means for detecting a thickness of the recording material, wherein the curl removing control means is configured to detect the moisture detected by the moisture amount detecting means. The operating condition of the curl removing unit is controlled based on the amount information, the image condition of the image formed by the image forming unit, and the thickness information detected by the thickness detecting unit. Item 6. The image forming apparatus according to any one of Items 1 to 5. 13. An image forming means for forming an image on a recording material, and an environmental condition detecting means for detecting an environmental condition, wherein the curl removing control means includes information on the moisture content detected by the moisture content detecting means. 6. The operating condition of the curl removing unit is controlled based on an image condition of an image formed by the image forming unit and an environmental condition detected by the environmental condition detecting unit. The image forming apparatus according to any one of the above. 14. A curl removing control unit comprising: an image forming unit for forming an image on a recording material; a thickness detecting unit for detecting a thickness of the recording material; and an environmental condition detecting unit for detecting an environmental condition. Are detected by the moisture condition information detected by the moisture condition detecting device, the image condition of the image formed by the image forming device, the thickness information detected by the thickness detecting device, and the environmental condition detecting device. The image forming apparatus according to claim 1, wherein an operation condition of the curl removing unit is controlled based on the environmental condition. 15. The image forming apparatus according to claim 13, wherein the environmental condition is temperature. 16. The image forming apparatus according to claim 13, wherein the environmental condition is humidity. 17. The image forming apparatus according to claim 11, wherein the image condition is an image density. 18. The image forming apparatus according to claim 11, wherein the image condition is an image density. 19. The image forming apparatus according to claim 11, wherein the image condition is the number of developed colors. 20. A single-sided image forming mode for forming an image on one side of a recording material through a predetermined image forming process, and a double-sided image forming mode for forming an image on the back side of the recording material through the image forming process. And at least one image forming mode of a multiplex image forming mode for forming multiple images on one side of the recording material by repeating the image forming process on the same surface. 20. The image forming apparatus according to claim 1, wherein the curl removing unit is controlled according to an image forming mode.