JP2007199330A - Image forming apparatus and method for removing dew condensation from image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively remove dew condensation in a simple manner on the downstream side of a fixing device in a system equipped with the fixing device for fixing an unfixed toner image on a sheet at least by heating. <P>SOLUTION: An image forming apparatus includes: an image forming means 2 for forming a toner image on the sheet 1; a fixing means 3 for fixing the unfixed toner image on the sheet 1 at least by heating; a guide chute 4 disposed at least just behind the downstream side of the fixing means 3 and conveying and guiding the sheet 1; and a dew condensation removing means 5 for making the image non-formed sheet 1 which has not passed through the fixing means 3 move to the guide chute 4 while being rubbed in an image non-forming process. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus for forming a toner image such as a copying machine or a printer using an electrophotographic system, an electrostatic recording system, or the like, and more particularly, an improvement of an image forming apparatus using a fixing device for heating a toner image. The present invention also relates to an improvement in a method for removing condensation in an image forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying machine or a printer, a heating type fixing device is mainly used for fixing a toner image formed on a sheet. In such a heating type fixing device, when the sheet is heated by the fixing device, moisture contained in the sheet evaporates from the sheet after fixing, and in particular, a sheet conveying guide (conveying guide) adjacent to the downstream side of the fixing device. As a result, a large amount of evaporated water adheres to the surface of the conveyance guide and the like, and condensation occurs on the surface of the conveyance guide or the like. Further, when the sheet heated by the fixing device passes through the conveyance guide, the conveyance guide itself is heated, and the conveyance guide causes dew condensation.

  On the other hand, when water droplets generated by such condensation adhere to the sheet passing through the conveyance guide, particularly in the case of double-sided printing in which image formation is performed on both sides of the sheet, the charge is not sufficient during image formation on the back side. Image defects such as missing prints (white spots) occur. In addition, a wet sheet due to adhesion of water droplets to the sheet may stick to the conveyance guide and cause jamming, or the visibility of the discharged sheet may be impaired.

In order to solve such a problem, a method of directly removing condensation on the photosensitive member with a sheet is known (for example, see Patent Document 1). In this patent document, when the dew condensation removal mode of the photoconductor is selected, the dew condensation on the photoconductor is directly removed using the sheet conveyed from the paper feeding unit without developing the photoconductor. A removal scheme is presented.
Therefore, it is assumed that the condensation removal on the downstream side of the fixing device is performed by applying such a condensation removing method to an image forming apparatus having a fixing device.

JP-A-8-234649 (Example, FIG. 3)

  However, if the sheet supplied from the upstream side of the fixing device is used to remove condensation on the downstream side of the fixing device, the sheet passes through the fixing device and the moisture from the sheet evaporates due to heating by the fixing device. On the other hand, condensation tends to occur on the downstream side of the fixing device. In addition, in the case where the nip fixing with the roll member is performed as the fixing device, since the oil component such as silicone oil is usually applied to the roll member in order to suppress the adhesion of the toner to the roll member, When the oil component adheres to the passing sheet, the sheet surface becomes hydrophobic, the water removal performance (water absorption performance) by the sheet is lowered, and the condensation cannot be removed effectively.

  The present invention has been made to solve the above technical problem, and in a system including a fixing device that fixes an unfixed toner image on a sheet by at least heating, condensation on the downstream side of the fixing device. It is possible to provide an image forming apparatus and a dew condensation removing method that can remove water easily and effectively.

  That is, as shown in FIG. 1, the present invention includes an image forming means 2 for forming a toner image on a sheet 1, a fixing means 3 for fixing an unfixed toner image on the sheet 1 by at least heating, and at least a fixing means. A guide chute 4 disposed immediately after the downstream side of 3 and conveying and guiding the sheet 1 and a non-imaged sheet 1 that has not passed through the fixing means 3 during the non-image forming process are slid relative to the guide chute 4. Condensation removing means 5 is provided.

  In such technical means, the image forming means 2 is not particularly limited as long as it forms a toner image on a sheet, and examples thereof include an electrophotographic method and an electrostatic recording method. The fixing unit 3 may be of a type that at least heats the sheet 1 during fixing. For example, the fixing unit 3 may be a type that forms a fixing nip with a heating roll and a pressure roll, or a lamp that uses near infrared rays or the like. A method using a heater, an IH method using induction heating, or the like may be used.

The “guide chute 4 disposed at least immediately after the downstream side of the fixing unit 3” in the present invention is, for example, the guide chute 4 disposed in the entire downstream side including a position far from the fixing unit 3. The guide chute 4 is likely to cause dew condensation, and is intended to indicate that at least an area where dew condensation is likely to occur is targeted.
Further, the sheet 1 used in the dew condensation removing means 5 may be an image forming sheet 1 or a dedicated sheet 1 having good water absorption, and preferably a surface treatment including a toner image. From the viewpoint of water absorption, it is preferable that the above is not performed. Note that “unformed image sheet 1” is intended to include the case where a sheet that has been printed on one side of the sheet 1 is used.

  The dew condensation removing unit 5 in the present invention has a detour path that bypasses the fixing unit 3, and the sheet 1 is conveyed from the upstream side to the downstream side of the fixing unit 3 through the detour path to perform dew condensation removal. It is preferable that the fixing unit 3 is bypassed to prevent excessive moisture evaporation from the sheet 1 by the fixing unit 3 and adhesion of oil to the surface of the sheet 1, thereby effectively removing condensation on the sheet 1. Will be able to do.

Further, the dew condensation removing means 5 preferably includes a removal sheet supply means for supplying a dedicated sheet 1 used for dew condensation removal on the downstream side of the fixing means 3. According to this, for example, a sheet unsuitable for image formation Even if it is 1, the sheet 1 having good water absorption can be used exclusively for condensation removal, and the condensation removal can be performed more effectively.
Further, as the removal sheet supply means, it is preferable to also serve as an accommodating portion for accommodating the sheet 1 after condensation removal, and furthermore, the removal sheet supply means is provided with a heating means for reducing the amount of water in the sheet 1. Preferably, according to these, the sheet 1 used for condensation removal can be used again, and the water absorption performance of the sheet 1 can be maintained by the heating means, and effective condensation removal is maintained. Will be able to.

Further, in the present invention, it is preferable that an image forming mode for operating the image forming means 2 and a condensation removal mode for operating the condensation removing means 5 are provided, and the image forming means 2 is stopped when the condensation removal mode is selected. According to this, dew condensation is effectively removed. At this time, the switching selection between the image forming mode and the dew condensation removal mode may be performed manually or automatically. Furthermore, as a mode to be automatically performed, at the stage when it is determined that condensation removal is necessary based on various information such as sensor information of temperature / humidity sensors and condensation sensors inside and outside the device, elapsed time since power ON, number of continuous runnings, etc. You just have to do it.
Note that when the condensation removal mode is selected, the fixing unit 3 may be stopped, or may be maintained in a state where the fixing unit 3 is operated. It becomes possible to reduce the humidity in the apparatus even slightly by heating by means of, or to shorten the warm-up time of the apparatus after removing condensation.

The present invention is intended not only for the above-described image forming apparatus but also for the dew condensation removing method. In this case, as shown in FIG. 1, image forming means 2 for forming a toner image on the sheet 1. And at least a fixing chute 3 for fixing an unfixed toner image on the sheet 1 by heating. At least a guide chute 4 disposed immediately after the fixing means 3 and conveying and guiding the sheet 1. On the other hand, the non-image forming sheet 1 that does not pass through the fixing means 3 is rubbed and removed in the non-image forming process to remove condensation.
According to such a condensation removal method, the water absorption of the sheet 1 used for condensation removal can be stably maintained, and effective condensation removal is possible.

According to the present invention, an image forming means for forming a toner image, a fixing means for fixing an unfixed toner image, a guide chute disposed at least immediately downstream of the fixing means and for conveying and guiding the sheet, Condensation removing means for sliding and moving the unformed image sheet that has not passed through the fixing means with respect to the guide chute during the image forming process can stably maintain the water absorption of the sheet for performing condensation removal. This makes it possible to remove condensation easily and effectively. Therefore, it is possible to provide an image forming apparatus that prevents the occurrence of image defects, jams, and the like caused by the influence of condensation.
Further, in an image forming apparatus including an image forming unit and at least a fixing unit that fixes an unfixed toner image by heating, at least a guide chute disposed immediately downstream of the fixing unit and conveying and guiding the sheet, Since non-image forming sheet that has not passed through the fixing means is rubbed and removed in the non-image forming process, condensation is removed, so it is easy and effective to prevent the occurrence of image defects and jams caused by the effect of condensation. Condensation removal method becomes possible.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
Embodiment 1
FIG. 2 shows a schematic diagram of Embodiment 1 of the image forming apparatus to which the present invention is applied. In the figure, the image forming apparatus according to the present embodiment employs, for example, an electrophotographic system, and includes an image forming unit 10 that forms a toner image, and a multi-stage that supplies sheets as sheets to the image forming unit 10. The sheet feeding cassettes 11 to 13 are accommodated so as to be drawable, and the fixing device 20 is disposed downstream of the image forming unit 10 in the sheet conveying direction.
Here, the image forming unit 10 is schematically shown, and the color and image forming method of the toner image are not particularly limited, and may form a monochrome toner image, or a color toner image may be formed. It can be formed. Further, when forming a color toner image, for example, a so-called rotary method in which the intermediate transfer belt is rotated when the toner image on the photosensitive member is multiplexed on the intermediate transfer belt, for example, the photosensitive member is exposed on the intermediate transfer belt. A so-called tandem system in which the bodies are arranged in parallel to perform multiplexing may be used.

In the present embodiment, a discharge tray 19 is provided on the downstream side of the fixing device 20 and on the side of the apparatus for discharging and storing paper.
The fixing device 20 includes, for example, a fixing roll 21 having a heating source such as a halogen heater inside, and a pressure roll 22 that is disposed opposite to the fixing roll 21 and nip-conveys a sheet to be fixed. The unfixed toner image formed on the paper is fixed by the image forming unit 10 by heating. Although the fixing device 20 of the present embodiment has shown a method of conveying a sheet by nip, it is not limited to this, and for example, a fixing method of heating a sheet in a non-contact manner may be adopted.

  Further, in the paper feed cassettes 11 to 13 of the present embodiment, feed rolls 31 to 33 corresponding to the respective paper feed cassettes 11 to 13 are arranged, and the feed rolls 31 to 33 are used to feed the respective paper feed cassettes. Only the top sheet of 11 to 13 is rolled out and sent out.

Next, a description will be given centering on the paper transport system in the image forming apparatus of the present embodiment.
The sheets fed from the sheet feeding cassettes 11 to 13 are guided to the first merging and conveying unit 14 through the respective sheet conveying paths R1 to R3. The toner image from the image forming unit 10 is transferred to the paper sheet that has been guided from the first merging and conveying unit 14 to the main conveying path R4 via the second merging and conveying unit 15 and the resist roll 16. At this time, the registration roll 16 sends out the paper at a predetermined timing after positioning the paper so that the toner image from the image forming unit 10 is transferred to the predetermined position of the paper.
The main transport path R4 passes through the fixing device 20 for fixing the unfixed toner image transferred onto the paper, and then passes through the junction portion 17, the transport rollers 34 and 37, and the discharge roller 18 to the discharge tray 19. Constitutes a route led to

  In particular, in this embodiment, a detour conveyance path R5 that bypasses the fixing device 20 from the middle of the main conveyance path R4 is provided around the fixing device 20, and in this example, this detour conveyance path R5 is downstream of the image forming unit 10. On the side, it bypasses the main transport path R4 and joins with the main transport path R4 at the junction 17 on the downstream side of the fixing device 20.

Further, in the present embodiment, a reverse conveyance path R6 for reversing and discharging the paper discharged to the discharge tray 19 extends substantially vertically downward from the conveyance roll 34 on the downstream side of the junction 17 of the main conveyance path R4. It is provided as follows. Therefore, for example, the sheet conveyed to the reverse conveyance path R6 is reversed by the conveyance rolls 35 and 36 in a state where the sheet is nipped by the conveyance rolls 35 and 36 in the reverse conveyance path R6. From 37, the sheet is reversely discharged to the discharge tray 19 through the discharge roll 18.
Furthermore, in the present embodiment, a return conveyance path R7 that is connected in the middle of the reverse conveyance path R6 and guides the sheet to the second merging conveyance section 15 in the main conveyance path R4 in a reversed state is provided.
These paper transport paths R1 to R7 are provided with an appropriate number of paper transport members (such as guide chutes and transport rolls) and switching members so as to ensure stable transport of paper.

In such a paper transport system, when a toner image from the image forming unit 10 is transferred onto the paper and fixed by the fixing device 20, a new image is formed on the back surface of the paper. It is necessary to guide the sheet that has exited 20 from the reverse conveyance path R6 to the return conveyance path R7.
On the other hand, the paper that has passed through the fixing device 20 tends to evaporate moisture contained in the paper due to heating by the fixing device 20, and in particular, the atmospheric humidity on the downstream side of the fixing device 20 increases. For this reason, dew condensation is likely to occur on the sheet conveying member (guide chute, conveying roll, etc.) installed in such an area. At this time, the transport roll is unlikely to cause dew condensation, so dew condensation on the guide chute is particularly problematic.

While such dew condensation depends on the material of the paper conveying member, it also depends on the temperature and humidity conditions inside and outside the image forming apparatus, the operating time of the apparatus, the number of sheets running, etc. To change.
If such dew condensation is left, especially when double-sided printing, moisture that has condensed on the paper that has been printed on one side has been deposited, and a sufficient transfer electric field is generated when the toner image is transferred from the image forming unit 10 onto the paper. Image defects such as white spots occur without acting. Therefore, in particular, the condensation removal of the guide chute disposed immediately after the downstream side of the fixing device 20 (in this embodiment, at least the guide chute installed in the main conveyance path R4 and the reverse conveyance path R6) is effectively removed. There is a need to do.

For this reason, in the present embodiment, the control device 40 provided in the image forming apparatus performs the process shown in FIG. 3 to remove condensation.
In the figure, the control device 40 counts temperature / humidity sensor information 41 from temperature / humidity sensors installed inside and outside the image forming apparatus, a power ON signal 42 generated when the power of the image forming apparatus is ON, and the number of prints. The control unit 40 compares the input information with various threshold values stored in the control unit 40. As a result, the image forming unit 10 operates as the image forming apparatus. The normal print mode 46 (corresponding to the image forming mode) and the dew condensation removing mode 47 for stopping the image forming unit 10 and removing the dew condensation in the apparatus are switched.
For example, when the temperature / humidity sensor information 41 exceeds a threshold, when the integration time of the power ON signal 42 exceeds the threshold, or when the paper passage signal 43 exceeds a predetermined count, the normal print mode 46 Is selected to switch to the condensation removal mode 47.

Here, an outline of sheet conveyance in the normal print mode 46 and the dew condensation removal mode 47 will be described with reference to FIG.
In the normal print mode 46, for example, a sheet fed from the sheet feeding cassette 11 is guided from the sheet transport path R1 to the main transport path R4. Then, after the toner image is transferred onto the sheet by the image forming unit 10, it is fixed by the fixing device 20 as it is through the main transport path R4. The sheet that has been fixed is discharged to the discharge tray 19 via the main conveyance path R4 as it is. When performing duplex printing, the sheet after fixing is reversed and returned from the main transport path R4 to the main transport path R4 via the reverse transport path R6 and the return transport path R7. After a new toner image is transferred to the back surface, the toner image is discharged to the discharge tray 19 through the fixing device 20.

On the other hand, when the condensation removal mode 47 is selected, for example, a sheet is sent out from the paper feed cassette 11, and the sent-out sheet is guided from the sheet transport path R1 to the main transport path R4. Then, the image forming unit 10 does not perform image formation, and the sheet is guided as it is downstream of the image forming unit 10 to the detour conveyance path R5, and then returned to the main conveyance path R4 and discharged from the discharge roll 18. It is discharged to the tray 19. At this time, in order to distinguish between the paper in the normal print mode 46 and the paper in the dew condensation removal mode 47 in the discharge tray 19, offset discharge is performed by moving the discharge roll 18 in a direction crossing the paper conveyance direction, Visibility is improved.
Further, in the condensation removal mode 47 of the present embodiment, the sheet is further fed out from the sheet feeding cassette 11, and the sheet is guided from the main conveyance path R4 and the detour conveyance path R5 to the reverse conveyance path R6. Then, the sheet guided to the reverse conveyance path R6 reverses the reverse conveyance path R6 by a reverse operation of a predetermined conveyance roll (in this example, the conveyance rolls 35 and 36) and is discharged from the discharge roll 18 to the discharge tray 19. The Needless to say, offset discharge is also performed at this time.

4A and 4B show the behavior of dew condensation on a guide chute (not shown in FIG. 2) disposed on the downstream side of the fixing device 20 in the present embodiment. FIG. 6 is a view showing that a paper (paper without an unfixed toner image) is allowed to pass through a guide chute with water droplets due to condensation without passing through the fixing device 20, and (b) shows a toner image being formed. It is shown that the sheet is guided to the guide chute through the fixing device 20.
That is, by allowing the paper to pass through the guide chute to which water droplets due to condensation have adhered, the water droplets on the guide chute are wiped off, and the water droplets can be prevented from adhering to the paper in the guide chute during the subsequent image forming process. For this reason, a uniform transfer electric field is applied even when an image is formed on the back side during double-sided printing, and image defects can be prevented from occurring. Such a guide chute may be used not only immediately after the fixing device 20 but also to allow other sheets of paper to pass through the guide chute in advance to remove condensation.

  As described above, in the condensation removal mode 47 of the present embodiment, the sheet is passed through the main conveyance path R4 portion and the reverse conveyance path R6 on the downstream side of the fixing device 20, so that the sheet conveyance paths R4 and R6 pass through these sheets. Condensation such as generated guide chutes can be wiped off by rubbing the paper, and the condensation can be removed easily and effectively. Therefore, it becomes possible to prevent the occurrence of image defects or the like in the subsequent normal print mode 46. At this time, since the paper used for condensation removal does not pass through the fixing device 20, the condensation removal is more effectively performed while the water absorption of the paper is sufficiently ensured.

In the present embodiment, a method is used in which two sheets are used in the condensation removal mode 47 and are passed through the main conveyance path R4 and the reverse conveyance path R6 on the downstream side of the fixing device 20, but the present invention is not limited to this. You may make it use the number of sheets suitably. Further, for example, only one sheet may be passed through the reverse conveyance path R6. Furthermore, as long as transportability is ensured as a paper to be used, a special paper (paper with high water absorption) may be used.
In addition, when switching to the dew condensation removal mode 47, dew condensation is performed by prompting the user to change the paper or input the paper cassette number containing the paper to be used, or by determining the paper cassette to be used in advance. You may make it designate the paper used for removal.

Further, in the present embodiment, as shown in FIG. 3, a method of switching to the dew condensation removal mode 47 by each of the temperature / humidity sensor information 41, the power ON signal 42, and the paper passage signal 43 is shown. However, the condensation removal mode 47 may be switched by any combination of these.
In the present embodiment, the paper used in the dew condensation removal mode 47 is differentiated from the normal print mode 46 by offset discharge on the discharge tray 19. It is also possible to provide an external purge tray and discharge the paper used for condensation removal to the purge tray.

Embodiment 2
FIG. 5 shows an outline of the second embodiment of the image forming apparatus to which the present invention is applied. The image forming apparatus according to the present embodiment is configured in substantially the same manner as in the first embodiment, except that sheets used for condensation removal are supplied from a sheet feeding cassette 51 provided on the downstream side of the fixing device 20. Different from the first embodiment. For this reason, unlike in the first embodiment, no detour path for detouring the fixing device 20 is provided. Components similar to those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted here.

  In the present embodiment, a paper feed cassette 51 for supplying paper for removing condensation is provided on the downstream side of the fixing device 20. The paper feed cassette 51 is provided with a delivery roll 52, and one sheet fed from the paper feed cassette 51 by the delivery roll 52 passes through a dedicated paper transport path R8 and is fixed in the main transport path R4. The merging section 17 on the downstream side of the merging section is joined to the main transport path R4.

Therefore, when the dew condensation removal mode is selected in the present embodiment, the sheet fed from the sheet feeding cassette 51 is guided from the sheet transport path R8 to the main transport path R4 and discharged to the discharge tray 19 by the discharge roll 18. Is done. Further, the next sheet is guided from the sheet conveyance path R8 to the reverse conveyance path R6, and is reversely discharged at a predetermined timing, and is discharged from the discharge roll 18 to the discharge tray 19.
As described above, in the present embodiment, dew condensation can be removed on the sheet transport paths R4 and R6 on the downstream side of the fixing device 20 by using a dedicated sheet stored in the sheet feeding cassette 51. Effective dew condensation can be removed, and occurrence of defects such as image defects during normal printing can be prevented.

  In the present embodiment, as in the first embodiment, the paper discharged to the discharge tray 19 may be offset discharge, or a purge tray (not shown) may be used. Further, the condensation removal of only the reverse conveyance path R6 may be performed on the sheet fed from the sheet feeding cassette 51, and the number of sheets to be used is not particularly limited. Furthermore, in the present embodiment, it becomes easy to make the paper to be used a dedicated paper with high water absorption, and it becomes easier to remove condensation more effectively.

Embodiment 3
FIG. 6 shows an outline of Embodiment 3 of the image forming apparatus to which the present invention is applied. The image forming apparatus according to the present embodiment is configured in substantially the same manner as in the second embodiment, except that sheets used for condensation removal are supplied from a sheet feeding cassette 53 provided on the downstream side of the fixing device 20. The same as in the second embodiment, but differs from the second embodiment in that the paper used for condensation removal is accommodated again in the paper feed cassette 53. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 2, and the detailed description is abbreviate | omitted here.

In the present embodiment, the paper feed cassette 53 for supplying paper for removing condensation is attached below the discharge tray 19. In addition to the feed roll 54, the paper feed cassette 53 is provided with a heater 55 for drying the paper.
Further, in the present embodiment, the paper transport path is a paper transport path R9 (partially configured by the reverse transport path R6) connected from the paper feed cassette 53 to the reverse transport path R6, and the reverse transport from the paper feed cassette 53. A feature is that a paper transport path R10 that extends in a direction different from the path R6 and is connected to the main transport path R4 and a paper transport path R11 that is provided substantially in parallel with the reverse transport path R6 are provided.

  In the present embodiment, since the sheet conveyance path is provided, when the condensation removal mode is selected, the sheet fed from the sheet feeding cassette 53 is guided to the reverse conveyance path R6 through the sheet conveyance path R9. As a result, the sheet is returned to the sheet feeding cassette 53 via the sheet conveying path R10. Alternatively, the sheet may be returned from the sheet conveyance path R9 to the sheet conveyance path R9 via the reverse conveyance path R6 and the sheet conveyance path R11 and accommodated in the paper feed cassette 53. As described above, by circulating the paper from the paper feed cassette 53, the condensation removal on the downstream side of the fixing device 20 can be effectively performed, and the occurrence of image defects in the normal mode can be prevented. become able to. Needless to say, a predetermined switch is provided in each paper transport path to switch the paper transport direction. Needless to say, the feed roll 54 of the paper feed cassette 53 also performs the reverse operation.

Furthermore, in the present embodiment, the paper used for condensation removal and absorbed is returned to the paper feed cassette 53. By providing the heater 55 in the paper feed cassette 53, the returned paper is fed into the paper feed cassette. The paper is dried in the paper 53, and the water absorption of the paper is ensured again. Therefore, even if reuse is performed, the condensation removal performance is sufficiently maintained.
In the present embodiment, the above-described configuration is shown as the paper transport path. However, the present invention is not limited to this, and it is only necessary to provide a paper transport path so as to return the paper used for condensation removal.

In the present embodiment, a method of repeatedly using one sheet is shown. However, for example, if a sheet feeding cassette 61 as shown in FIG. 7 is used as the sheet feeding cassette 53, a plurality of sheets are used. It is also possible to remove the dew and store it in the paper feed cassette 61.
In FIG. 7, a paper feed cassette 61 includes a feed roll 62 that feeds paper, a transport roll 63 that stores paper, a switch 64 that switches a path for transporting paper between the feed roll 62 and the transport roll 63, and a heater. 65 is provided.

In such a paper feed cassette 61, in the dew condensation removal mode, one sheet on the lower side is sent out by the feed roll 62, and when the paper after the condensation removal is returned to the paper feed cassette 61, the returned paper is switched. It is guided to the transport roll 63 side by the container 64. And it comes to be accommodated on the top of the paper in the paper feed cassette 61. In the paper feed cassette 61, the paper from which condensation has been removed by the heater 65 can be preferentially dried among the stored paper.
By using such a configuration as the paper feed cassette 61, it becomes easy to use a plurality of sheets on which condensation is removed, and condensation can be removed effectively.

1 is an explanatory diagram showing an outline of an image forming apparatus according to the present invention. 1 is an explanatory diagram showing an overview of an image forming apparatus according to Embodiment 1. FIG. 2 is an explanatory diagram illustrating a control device according to Embodiment 1. FIG. It is explanatory drawing which shows the effect | action of Embodiment 1, (a) is at the time of dew condensation removal, (b) shows the time of image formation. FIG. 6 is an explanatory diagram illustrating an overview of an image forming apparatus according to a second embodiment. FIG. 10 is an explanatory diagram illustrating an overview of an image forming apparatus according to a third embodiment. FIG. 10 is an explanatory diagram showing a modification of the third embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Sheet | seat, 2 ... Image forming means, 3 ... Fixing means, 4 ... Guide chute, 5 ... Condensation removal means

Claims (7)

An image forming means for forming a toner image on the sheet;
Fixing means for fixing an unfixed toner image on the sheet by at least heating;
A guide chute disposed at least immediately downstream of the fixing unit and for conveying and guiding the sheet;
An image forming apparatus comprising: a condensation removing unit that slides an unimaged sheet that has not passed through a fixing unit during a non-image forming process. The image forming apparatus according to claim 1.
The dew condensation removing means has a detour path that bypasses the fixing means, and the dew condensation is removed by conveying the sheet from the upstream side to the downstream side of the fixing means via this detour path. Image forming apparatus. The image forming apparatus according to claim 1.
An image forming apparatus, wherein the dew condensation removing means comprises a removal sheet supply means for supplying a dedicated sheet used for dew condensation removal on the downstream side of the fixing means. The image forming apparatus according to claim 3.
The image forming apparatus according to claim 1, wherein the removal sheet supply unit also serves as a storage unit that stores the sheet after condensation removal. The image forming apparatus according to claim 4.
The image forming apparatus, wherein the removal sheet supply unit includes a heating unit that reduces a moisture content in the sheet. The image forming apparatus according to claim 1.
An image forming apparatus comprising: an image forming mode for operating an image forming unit; and a dew condensation removing mode for operating a dew condensation removing unit, wherein the image forming unit is stopped when the dew condensation removing mode is selected. An image forming means for forming a toner image on the sheet;
In an image forming apparatus comprising at least fixing means for fixing an unfixed toner image on a sheet by heating,
At least at the downstream side of the fixing unit, the guide chute for conveying and guiding the sheet is rubbed with the non-formed sheet that has not passed through the fixing unit during the non-image forming process to remove condensation. A method for removing condensation.

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