JP2009237514A - Cooling device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling device working well for cooling of transfer paper S in a high speed machine fusing toner on the transfer paper by a heat fixing device, and especially, effectively functioning for double-sided image formation. <P>SOLUTION: The cooling device has: a first liquid cooling means disposed on the downstream side of a fixing means heating and fixing a toner image on a transfer medium in an image forming process, for cooling the transfer medium; and a second liquid cooling means on a carriage route for newly leading the transfer medium to the imaging forming process so as to form the toner image on a second face. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cooling device (cooling structure) and an image forming apparatus for transfer paper that has passed through a heat fixing device that fixes a toner image on the transfer paper by heat, such as a copying machine or a printer.

2. Description of the Related Art Conventionally, an image forming apparatus that forms a toner image on a latent image carrier and transfers the toner image onto a transfer sheet to form an image is well known. In this image forming apparatus, the speed has been increased according to the user's request, and in particular, there are some which perform high-speed copying of 40 sheets or more per minute in a copying machine or the like.
In a high-speed copying machine having a copy speed of 40 sheets per minute or more, fixing means for fusing and fusing toner to transfer paper with heat, the temperature of the transfer paper rises to about 120 ° C. by heat during fixing. For this reason, when copying is repeated one after another in a short time, when double-sided images are formed such as when copying on both sides, or when the output transfer paper overlaps or when copying is repeated again on the back side, The toner is not cooled sufficiently, so the transfer paper may stick to each other due to the viscosity of the toner, or the transfer paper may curl due to heat and cause jamming. It was a problem.
In general, in the image forming apparatus, the fixing unit heats the toner to melt and fix it on the transfer paper, but the temperature of the transfer paper after fixing reaches about 120 ° C., which causes the temperature in the apparatus to rise. In particular, in the double-sided copy mode, the transfer paper is transported one more time, and thus a temperature rise due to heat becomes a problem in various places. In view of this, measures are taken to rapidly lower the temperature by providing means for cooling the transfer paper after fixing. As a highly efficient cooling technique, a cooling device to which a liquid cooling method using a liquid is applied is also used.
In order to solve the above problem, it is necessary to cool the transfer paper immediately after fixing the toner. Therefore, Patent Document 1 discloses a method for cooling transfer paper using a heat pipe having excellent thermal conductivity. In Patent Document 1, the transfer paper is cooled using a pair of upper and lower heat pipes. In this method, the heat of the transfer paper is transported by a heat pipe, and the heat radiation fin provided at the end of the heat pipe is cooled by a fan. In this method, it is important to efficiently cool the heat-dissipating fins, and therefore, the fan is forcibly cooled by a fan. However, a large sirocco fan is required for that purpose, and naturally, side effects such as an increase in noise occur.

In addition to this, in Patent Document 2, the hollow material constituting the heat pipe heat dissipating part is devised to increase the heat dissipating efficiency by reducing only the thickness of the hollow material, and the air intake and exhaust of the cooling fan is contrived. I am doing. However, sufficient performance cannot be obtained in the transfer paper cooling application of the image forming apparatus as a premise of the present invention. This heat pipe method is a cooling means that also serves as transfer paper transfer. However, in a high-speed machine with a copy speed exceeding 100 cpm, the transfer paper transfer speed is 500 mm / s, and the rotation speed of the heat pipe of φ30 mm is also high. It will exceed 300 rpm. Then, the liquid transport function due to the evaporation of the liquid in the heat pipe and the capillary phenomenon is lowered, and as a result, the thermal resistance becomes very large, and there is a possibility that it cannot be applied essentially.
As described above, if the cooling is insufficient, the image is deteriorated as a result of re-entering the image forming process while the temperature of the transfer paper is about 90 ° C. at the time of double-sided copying or the like. Due to heat dissipation, etc., it will increase the temperature inside the machine. Therefore, there is a demand for a technique for cooling the transfer paper after fixing more efficiently.
Patent Document 3 discloses a method of circulating and cooling a liquid, referred to as a liquid cooling method, but the temperature cannot be lowered sufficiently by passing the transfer paper through the liquid cooling roller only once. Also, Patent Document 4 discloses a technique in which liquid cooling rollers and heat pipes are arranged one above the other and the transfer paper is passed between them to cool, but as a result of the small contact area, a sufficient cooling effect cannot be obtained. In some cases, more efficient ones are desired.
JP-A-10-207155 JP-A-11-007218 2006-3819 2006-225115

  SUMMARY OF THE INVENTION Accordingly, the present invention provides a new cooling device that is effective for cooling transfer paper such as a high-speed copying machine or printer that fuses toner to transfer paper with a thermal fixing device, and particularly functions effectively during double-sided image formation. It was created for the purpose.

In order to solve the above problems, the cooling device of the present invention is a cooling device for an electrophotographic image forming apparatus having a double-sided image forming function as claimed in claim 1, wherein the image forming step And a first liquid cooling means disposed on the downstream side of the fixing means for fusing and fixing the toner image on the first surface of the transfer medium with heat to cool the heated transfer medium, and subsequently When a toner image is formed on the second surface of the transfer medium, a second liquid is provided on the transport path for guiding the transfer medium to the image forming process again to further cool the transfer medium. A cooling means is provided.
According to a second aspect of the present invention, in the cooling device of the first aspect, the first liquid cooling means and / or the second liquid cooling means includes a liquid cooling type liquid cooling roller that cools a heat source by liquid circulation, and The transfer pressure roller or the transfer pressure belt presses the transfer medium against the liquid cooling roller.
According to a third aspect of the present invention, in the cooling device according to the second aspect, a plurality of the liquid cooling rollers are installed in at least one of the cooling devices, and each of the plurality of liquid cooling rollers It is characterized in that the pressure applied by the conveying pressure roller, which is brought into pressure contact with the liquid cooling roller, is individually variable.

According to a fourth aspect of the present invention, in the cooling device according to the second aspect, the conveyance pressure belt is provided with a liquid cooling roller for cooling the belt in contact with the surface in contact with the transfer medium. It is characterized by that.
According to a fifth aspect of the present invention, in the liquid cooling apparatus according to any one of the first to fourth aspects, the second liquid cooling means is configured to liquidate a transport path cover of a reversing double-sided unit for double-sided image formation. A fixed side cooling means for cooling the transfer medium that is cooled and temporarily stopped on the transport path cover; and a transfer medium stationary position on the transport path cover so as to be movable to the upper surface side of the transfer medium, A liquid-cooled upper surface cover that moves and contacts the upper surface of the transfer medium in a stationary state, and liquid-cooled moving-side cooling means for cooling the liquid-cooled upper surface cover, and the upper surface of the transport path cover And the liquid-cooled upper surface cover are configured to contact and cool the stationary transfer medium sandwiched from both sides.
According to a sixth aspect of the present invention, there is provided an image forming apparatus comprising the cooling device according to any one of the first to fifth aspects.

According to the present invention, in an image forming apparatus having a double-sided image forming function, it is possible to cool the heated transfer paper with high efficiency, so that it functions particularly effectively during double-sided image formation.
In other words, with the conventional air-cooling method and heat pipe, the transfer paper temperature, which was about 120 ° C after fixing, can only be lowered to about 90 ° C, and during continuous copying, the internal temperature rose and reliability was impaired. However, by disposing the cooling devices using the liquid cooling method in two places as in the present invention, the temperature of the transfer paper after passing through both cooling devices can be lowered to about 50 ° C., and the image quality is improved. It can be improved. In addition, fan noise can be reduced, which is effective in improving the office environment.
According to the second aspect of the present invention, the liquid cooling roller or the conveyance pressure belt that presses the liquid cooling roller and the transfer medium of the conveyance system against the liquid cooling roller is configured to be a pressure type. The cooling efficiency of the cold roller can also be improved and the temperature of the transfer paper can be further lowered. The installation space required for cooling can also be reduced, and downsizing and improved reliability can be achieved.
According to the third aspect of the present invention, when the transfer paper is insufficiently cooled and the temperature of the transfer paper remains high as in the prior art, the hot transfer paper increases the internal temperature of the apparatus during double-sided copying. However, it is possible to further improve the performance of the copying machine by preventing the temperature of the transfer paper from increasing by using a plurality of liquid cooling rollers as in the present invention. became. Copy productivity can be increased by developing ultra-high speed machines.
In the case of the belt conveyance, a large contact area with the liquid cooling roller can be obtained, but conventionally, the temperature of the conveyance belt rises and the cooling efficiency is gradually lowered during continuous use. This can be solved by the invention according to claim 4. This improves image quality and device reliability.
According to the invention described in claim 5, until now, the transfer medium such as transfer paper can be conveyed to the reversing duplex unit while the temperature is high, and sent again to the paper feed for the back side copy. If the frequency becomes frequent, the temperature of the reversing duplex unit gradually rises and raises the temperature inside the machine. However, the temperature of the device can also be suppressed by cooling the reversing duplex unit with liquid cooling. This is also effective in reducing the image quality, and this also leads to image quality and device reliability.

  As described above, generally, in the fixing process in the image forming apparatus, the toner is heated and melted and fixed on the transfer paper, but the temperature of the transfer paper after fixing reaches about 120 ° C. In particular, in the double-sided copy mode, since the transfer paper is conveyed once more, temperature rise due to heat becomes a problem in various places. Therefore, in the present invention, as a means for cooling the transfer paper after fixing, a cooling device using a liquid cooling method using a liquid known as a highly efficient cooling technique is adopted, and not only in one place but also in duplex copying. A second liquid cooling device is installed in the route for transferring the transfer paper to lower the temperature. Furthermore, a third liquid cooling device is further provided for the purpose of preventing the transfer paper that has been copied from being transferred to a paper discharge tray or a paper discharge port while being hot and becoming uncomfortable for a person who holds it.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a cross-sectional view of an image forming apparatus (copier) to which the present invention is applied. In the figure, reference numerals are assigned to the respective components. However, since the operation of the entire image forming apparatus is well known, in this specification, the fixing device and the transfer, which are mainly relevant to the electrophotographic process and the invention, are transferred. Only the paper cooling device will be described in detail, and description of other parts will be simplified or omitted. Incidentally, for example, Japanese Patent Application Laid-Open No. 2006-259212 by the applicant of the present application details the detailed configuration of an image forming apparatus substantially equivalent to the present embodiment.
The basic configuration of the image forming apparatus will be described first. The copying machine of FIG. 1 includes an image forming processing unit 120, a fixing device 25, and a transfer paper reversing unit 28 inside an image forming apparatus main body 150. A document scanning unit 300 is provided on the upper surface of the image forming apparatus main body 150 and functions as a copying machine. The document scanning unit 300 shown in FIG. 1 can use an automatic document feeder (ADF) 400 that can automatically feed a document such as a document toward the scanning unit. Below the image forming apparatus main body 150 is a paper feed table 200.

The image forming processing unit 120 located at the upper part of the image forming apparatus main body 150 is formed on a photoconductor used as an image carrier, similarly to known image forming apparatuses such as a printer, a copying machine, a facsimile machine, and a printing machine. The electrostatic latent image is subjected to visible image processing using toner.
Although the illustrated image forming processing unit 120 has a well-known configuration, in brief description, four sets of image forming means 18 and an intermediate transfer belt (intermediate transfer member) 50 are provided for each color, and the lower surface side of the intermediate transfer belt 50 is provided. Is provided with a secondary transfer device 22. In each image forming unit 18, a drum-shaped photoconductor 10 is rotatably provided as an image carrier. Around each photoconductor 10, a charging device, an exposure device, a developing device, a transfer device, and a cleaning device for performing image forming processing along the rotation direction of the photoconductor 10 set in the counterclockwise direction are arranged. ing.
In each image forming unit 18, when the photosensitive member 10 is uniformly charged by the charging device, writing according to image information is executed by scanning with laser light to form an electrostatic latent image, and the electrostatic latent image is formed. The image is subjected to visible image processing with toner supplied from the developing device.
Each image on the photoreceptor 10 that has been subjected to the visible image processing is transferred onto the intermediate transfer belt 50 in an overlapping manner. This image is electrostatically transferred using a secondary transfer device 22 to a transfer sheet S (recording sheet) as a recording medium. The transfer paper S is fed out from a paper feed cassette denoted by reference numeral 144 in FIG. 1, registered at a registration timing by a registration roller 147, and fed toward the secondary transfer device 22 (transfer area). Thus, after the toner image is transferred to a transfer medium such as the transfer paper S, it is conveyed by the secondary transfer belt 24 and fixed by the fixing device 25 using a heat roller fixing method.

Here, as a main part deeply related to the present invention, a first cooling device having a characteristic configuration for cooling the fixing device 25 and the transfer sheet S passing through the fixing device 25 with high efficiency will be described in detail.
In FIG. 2, the transfer paper S as a transfer medium is introduced from the fixing device to the downstream side and further into the double-sided copying path, conveyed, reversed, and then retransmitted (joined) to the reprocessing path (fixing). The unit schematic diagram of the apparatus, the reversing duplex unit, the first and second liquid cooling devices, etc.) is shown. In the image forming apparatus of this embodiment, a first cooling device 81 and a second cooling device 91 are incorporated as a unit.
In FIG. 2, reference numeral 25 denotes a fixing device, and the transfer paper S in a state where a full color toner image is transferred from the transfer paper entrance 25 ′ and toner is electrostatically attached is conveyed and moved. The fixing device 25 includes a fixing belt 26 ′ that is an endless belt stretched around the heating roller 26, and a pressure roller 27 that is pressed against the fixing belt 26 ′. The transfer sheet S and the toner are welded by heat while being pressed at the nip portion formed by the above. When the transfer sheet S passes through the fixing device 25, a transfer image (full color toner image) carried on the surface by heat and pressure is heated and fixed on the transfer sheet S. On the downstream side of the fixing device 25, a first cooling device 81 as a first liquid cooling means described later is disposed, and the heated transfer sheet S after fixing is transferred to the first cooling device 81. Transported and cooled. Thereafter, in the case of single-sided processing, the transfer sheet S is switched by the switching claw 55 and discharged by the discharge roller 56 and is stacked on the discharge tray 57.

The first cooling device 81 will be described. FIG. 3A is a perspective view clearly showing the arrangement and configuration of the fixing device 25 and the first cooling device 81 as the first cooling means in the present embodiment, and FIG. 3B is the first cooling device. It is an expanded sectional view which shows the structure of 81 part. FIG. 4 is an enlarged cross-sectional view for explaining the configuration of the urging means in the first cooling device 81. In each figure, a cooling roller 81a of the first cooling device 81 provided close to the downstream of the fixing device 25, and two conveying rollers (conveying pressure rollers) 81b in pressure contact with the cooling roller 81a, A state is shown in which two transfer sheets S clearly indicated by hatching are conveyed sequentially between the gaps (nip portion).
After the toner is fixed on the downstream side of the fixing device 25, the liquid is allowed to flow in an internal sealed space in the cooling roller 81 a (having an inflow port and an outflow port that are not shown and forming a part of the flow path). It functions as a (liquid type) cooling device that immediately lowers the temperature of the transfer paper S.
The cooling roller 81a (also referred to as a liquid cooling roller or a heat pipe roller) has a structure that can be rotated at both ends, called a rotary joint, and does not leak even when refrigerant flows in and out. The roller surface is finished relatively smoothly with stainless steel, nickel, chrome plating or the like. Although the diameter of the cooling roller 81a can be arbitrarily selected, a diameter of about 20 mm to 50 mm is generally used. On the other hand, the conveyance roller 81b may be a normal metal bar.

In this type of liquid cooling apparatus, it is necessary to bring the transfer paper to be conveyed into contact with a liquid cooling heat exchanger, in this case, a liquid cooling roller, for heat transfer. Stronger is better. Therefore, a roller (or a belt as exemplified later) is used as the pressing means, and a mechanism capable of pressing the transfer paper against the liquid cooling roller is attached.
Although not shown, the transport roller 81b is pivotally supported by a long hole so as to be movable in the vertical direction. The upper and lower rollers are pressed against each other by an urging means including a pressure spring, and the transfer sheet S is surely pressed against the cooling roller 81a to move the heat. Of course, the conveyance roller 81b may also be configured to function as a cooling roller.
As shown in FIG. 4, the urging means for pressing the conveying roller 81b against the cooling roller 81a is provided by supporting the shaft end portion of the conveying roller 81b as appropriate by a shaft hole 81d. The plate-shaped spring metal fitting 81c and the pressure spring (coil spring) 81f, and the pressure spring which is hung between the engagement portions 81g through the engagement hole 81e provided at the free end of the spring metal attachment 81c. The conveying roller shaft end that is urged by 81f and abuts against the locking tongue piece 81h at the intermediate portion of the spring fitting 81c is pressed toward the cooling roller 81a.
In single-sided copying, the fixed transfer sheet S is cooled by the first cooling device 81 and immediately discharged from the inside of the apparatus by the switching claw 55 and stacked on the discharge tray 57. However, when performing double-sided image formation processing. The transfer sheet S that has been fixed and cooled by the first cooling device 81 is sent to the transfer sheet reversing unit 28 by switching the switching claw 55.

As shown in FIG. 2, in the present image forming apparatus, transfer for inverting the transfer paper S in order to form an image on both sides of the transfer paper S in the vicinity of the secondary transfer device 22 and the fixing device 25. A paper reversing unit (reversing duplex unit) 28 is arranged in a state in which a second cooling device 91 as a second cooling means is incorporated. Then, the transfer sheet S having the first surface fixed and cooled by the first cooling device 81 is further passed through the switching claw 55 to the transfer sheet reversing unit 28 by the roller 93 and the roller 94 further downstream. Here, it reaches a second cooling device 91 which will be described later in detail.
That is, in the case of double-sided printing, the transfer sheet S undergoes initial fixing and cooling, and then the conveyance direction is changed downward, and the transfer sheet reversing unit 28 is configured to include a conveyance path cover and a liquid-cooled upper surface cover. It is conveyed to. The transfer sheet S that has reached the transfer sheet reversing unit 28 is reversed in the transport direction and exits the transfer sheet reversing unit 28 from the rear end of the sheet (switchback operation). By this operation, the front and back of the transfer paper S can be reversed. At this time, the transfer sheet S is cooled again by the second cooling device 91 (second liquid cooling means).

Here, the 2nd cooling device 91 characterizing this embodiment is explained.
FIG. 5 is a perspective view showing the transfer sheet reversing unit 28 including the mounted second cooling device 91. FIG. 6 is an enlarged sectional view showing a second cooling device (liquid cooling device) 91 as the second cooling means of the present embodiment. The second cooling device 91 has a structure in which the transfer paper S is sandwiched and cooled between the transport path cover 91a and the movable transport upper surface guide 91b.
As clearly shown in FIG. 6, the second cooling device 91 is a bed-like A3 transfer serving as a lower mounting surface of a portion (static position) where the transfer paper S stays in the upper portion of the transfer paper reversing unit 28. A liquid cooling section formed by a paper-sized transport path cover 91a and a movable transport upper surface guide 91b disposed so as to cover it is provided as a main part. The transport path cover is cooled by a liquid-cooled fixed side cooling means. Further, the liquid-cooled upper surface cover is cooled by a liquid-cooled moving side cooling means.
That is, the liquid cooling section is a hollow flat metal box, and the inside is a conveyance path cover 91a having a flow path structure in which a refrigerant cooled by a well-known refrigerant cooling heat exchange device (not shown) and a movable type cover. The transfer upper surface guide 91b is placed above and below the transfer path, and the transfer sheet S is cooled by flowing a liquid through the flow path structure. The hollow portion may be a single space, but an appropriate support wall (partition wall) may be provided along the direction in which the refrigerant flows. Further, as another form, a structure in which a metal pipe serving as a flow path is meandered in a planar manner and arranged and joined to substantially the entire region between two parallel metal plates may be used. In addition, about the structure which moves the conveyance upper surface guide 91b, it is sufficient to use an existing technique suitably, and it does not touch here.

In this liquid cooling section, the transfer sheet S is retained between the transport path cover 91a and the transport upper surface guide 91b retracted upward by a device control section (not described in detail). The transfer sheet S is efficiently cooled by being lowered by being driven and pressed against the transport path cover 91a. As described above, both the transport path cover 91a and the transport upper surface guide 91b are metal boxes that are filled with refrigerant and pass through, and function efficiently as a liquid cooling device. In this way, the transfer paper S is reversed by the transfer paper reversing unit 28 and further sufficiently cooled by the second cooling means (second cooling device 91).
The transfer sheet S that has been turned upside down does not return to the fixing device direction, and is further conveyed by the discharge roller 95 and rollers 96 to 99, and is fed again from the duplex retransmission port 28a for duplex copying. To join the original paper feed path. Thereafter, the paper is guided again to the secondary transfer device 22 for the back surface copy processing process on the back surface of the transfer sheet S, and after the toner image is transferred to the back surface in the same manner as the front surface printing, the fixing device 25 is again connected. After passing through the first cooling device 81, the transfer sheet S is switched by the switching claw 55 and discharged by the discharge roller 56 and stacked on the discharge tray 57 in the same manner as in the case of single-side processing. The above is the double-sided printing operation.

As described above, according to the apparatus of the present embodiment, immediately after the image is fixed, the fixing toner image after fixing and the carrying transfer paper are efficiently cooled by the cooling roller 81a as the first cooling unit of the liquid cooling method. ing. Further, in the case of duplex copying, the second cooling is performed in the transfer sheet reversing unit 28 disposed in the transport path during the process of transporting the image-carrying transfer sheet for image formation on the second surface. Thus, it is possible to maintain the image quality by devising to sufficiently lower the temperature of the transfer paper carrying the toner image on one side.
Further, as a secondary effect, at the time of duplex copying, as a result of further cooling by the second cooling device 91 during the second surface processing process and passing through the first cooling device 81 after fixing, The transfer paper toward the paper discharge port is hot and no longer feels uncomfortable when held in a hand, unlike conventional devices. Moreover, the cooling in the reversing unit part also leads to suppression of temperature rise in the machine.

[Second Embodiment]
The cooling device in the present invention is not limited to the configuration described above. FIG. 7 shows another embodiment of the first cooling means that can be used in the above-described embodiment apparatus, in a layout diagram of the cooling roller and the conveyance pressure roller. The first cooling device 81 of the second embodiment is simplified by using only one conveying roller 81b as compared with that of the first embodiment, and the individual elements themselves are the first embodiment. The form is the same. Although not shown, the same biasing means as that described in FIG. 4 is provided, the cooling roller 81a, the only conveying roller 81b disposed opposite thereto, the spring fitting 81c, and the pressure spring 81f. The cooling device is configured.
As in the previous example, the cooling roller 81a has a structure that can be rotated at both ends, called a rotary joint, and does not leak even when refrigerant flows in and out. Then, the upper cooling roller 81a and the lower conveying roller 81b are pressed against each other by a pressing spring fitting 81f, and the transfer sheet S can be pressed against the cooling roller 81a to move heat.

[Third Embodiment]
Furthermore, another embodiment of the first cooling means that can be used in the above-described embodiment apparatus is shown in the layout diagram of the cooling roller, the conveyance pressure roller, and the like in FIG. In the third embodiment, two sets of first cooling devices 81 (here, referred to as cooling roller pairs 81b ′ for convenience) corresponding to the second embodiment are arranged close to each other. Accordingly, the individual elements themselves are the same as those in the first and second embodiments, and description thereof will not be repeated. In the figure, only the cooling roller pair on the downstream side is also illustrated with the biasing means. Each cooling roller pair 81b 'includes a cooling roller 81a, a conveying roller 81b disposed to face the cooling roller 81a, a spring fitting 81c, and a pressing spring 81f. The cooling efficiency as the first cooling device 81 is increased by passing the cooling section (cooling roller pair 81b ′) twice continuously.

[Fourth Embodiment]
In the apparatus described in the first embodiment, the second cooling apparatus having the structure shown in FIGS. 5 and 6 is used, but the second cooling apparatus is not limited to this. Any of the apparatuses using the cooling roller described as the first cooling apparatus may be used. As an example, FIG. 9 shows an example in which a cooling device equivalent to that shown in FIG. 7 is used as the second cooling means. FIG. 9 is an enlarged cross-sectional view in the case where a cooling roller type cooling device is mounted as the second cooling device in the transfer paper reversing unit 28 in the image forming apparatus of FIG.
Since all the parts in the figure have already been individually described, the description here will not be repeated, but when performing double-sided copying, after cooling with the first cooling means of the liquid cooling method, In the process of transporting the image-carrying transfer paper for image formation on the second surface, the transfer paper reversing unit 28 disposed in the transport path performs the second cooling by the second cooling device, and the toner image is formed on one surface. Since the temperature of the transfer paper carrying the toner can be lowered sufficiently, the object of maintaining the image quality can be achieved.

[Fifth Embodiment]
As the first cooling device, in each of the embodiments described so far, all have a configuration in which the conveyance roller 81b is opposed to the cooling roller 81a, but an endless belt is used instead of the conveyance roller. It is also conceivable to use the configuration as a first or second cooling device.
FIG. 10 shows an example of the configuration of the first cooling device for the belt on the conveying side (other parts of the device are the same as those in the above-described embodiments, and the description thereof is omitted). In FIG. 10, the reference numeral 81a indicates a cooling roller equivalent to the above-described embodiment, and the reference numeral 82a indicates a conveyance pressure belt. A tension is applied between the driving support roller 82b and the support roller 82c. A nip is formed with the cooling roller 81a. The transfer sheet S is transported from the direction of the arrow, rides on the belt, is cooled by the liquid cooling type cooling roller 81a, and is discharged to the support roller 82c side.

[Sixth Embodiment]
The number of cooling rollers is not limited to one, and a cooling device can be configured by using a plurality of cooling rollers 81a. As an example in the case of using a plurality of cooling rollers 81a, FIG. 11 shows a configuration example in which the cooling rollers 81a are doubled in the first cooling device. This is a configuration in which the cooling roller 81a is connected in series by being brought into contact with the upper surface of the surface of the conveying pressure belt 82a. In FIG. 8, the conveyance side is a pressure roller, but the conveyance side may be a belt. The cooling function is further enhanced, which is preferable. In addition, in FIG. 11, you may make it provide the tension roller which served also as the conveyance function between the cooling rollers 81a. A cooling roller may be used for the tension roller.
[Seventh Embodiment]
Furthermore, as shown in FIG. 12, in order to cool the surface of the conveyance pressure belt 82a in FIG. 10, an additional cooling roller 83a is provided in contact with the lower surface of the surface of the conveyance pressure belt 82a. However, it is also preferable because the cooling function is further strengthened. In FIG. 12, the cooling roller 83a is installed below the conveying pressure belt. However, the present invention is not limited to this configuration example, and the surface may be cooled, and the position thereof may be any place that can be installed spatially. It does n’t matter where you are.

Although the present invention has been described with the embodiment, the present invention is not limited to the above-described embodiments. In the embodiment described above, the second cooling unit incorporated in the transfer sheet reversing unit is shown, but the configuration is not necessarily limited to this. In short, after passing through the first cooling means, the transfer paper S is cooled again before the fixing process, preferably before the transfer process, in the transfer paper S conveyance path for image formation on the second surface. Just do it. Therefore, a cooling device having the same configuration as each configuration described as the first cooling device 81 in the embodiment can be provided at an appropriate position and used as the second cooling device.
In addition, a third cooling device may be further arranged in the conveyance path from the switching claw 55 to the paper discharge tray 57. According to this configuration, the transfer sheet S (recording medium) is sufficiently cooled after passing through the fixing device in either case of single-sided or double-sided image formation. Can more reliably prevent discomfort.

1 is a schematic view of an image forming apparatus equipped with a cooling device according to the present invention. FIG. 5 is a schematic unit diagram of each related part until the transfer sheet S is transported downstream from the fixing device to the duplex copy path in the embodiment apparatus. (A) is the perspective view which clarified arrangement | positioning / structure of the 1st cooling device as a fixing device and 1st cooling means in embodiment, (b) is an expanded sectional view of a cooling device part. It is an expanded sectional view explaining the example of a structure of the urging means of the 1st cooling device in embodiment. It is the perspective view which showed the structure of the transfer paper inversion unit and 2nd cooling device in embodiment. It is the expanded sectional view which showed the structure of the liquid cooling part of the 2nd cooling device in embodiment. FIG. 6 is an arrangement diagram of a cooling roller and a conveyance pressure roller, explaining a second embodiment of the first cooling means. FIG. 6 is an arrangement diagram of a cooling roller and a conveyance pressure roller, explaining a third embodiment of the first cooling means. FIG. 10 is a layout diagram of rollers in a fourth embodiment in which a cooling roller type liquid cooling unit is mounted as a second cooling means. FIG. 3 is a layout diagram illustrating an embodiment of a cooling roller type liquid cooling unit that employs a conveyance pressure belt on the conveyance side as a first cooling means. It is a layout view showing the configuration of another sixth embodiment of the first cooling means. It is an arrangement drawing showing the composition of a different 7th embodiment of the 1st cooling means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Photoconductor, 18 Image formation means, 22 Secondary transfer apparatus (transfer area), 24 Secondary transfer belt, 25 Fixing apparatus, 25 'Transfer paper entrance, 26 Heating roller, 26' Fixing belt, 27 Pressure roller, 28 Transfer sheet reversing unit, 28a double-sided retransmission port, 50 intermediate transfer belt, 55 switching claw, 56 discharge roller, 57 discharge tray, 81 first cooling device (first cooling means), 81a cooling roller (liquid cooling roller) , 81b Conveying roller (conveying pressure roller), 82a Conveying pressure belt, 82b, 82c Support roller, 83a Cooling roller, 91 Second cooling device (second cooling means), 91a Conveying path cover, 91b Conveying upper surface guide , 95 discharge rollers, 96-99 rollers, 120 image forming processing unit, 150 image forming apparatus main body, 144 paper feed cassette, 147 Jisutorora, 200 feed table, 300 original scanning unit, 400 an automatic document feeder (ADF), S transfer sheet

Claims (6)

A cooling device for an electrophotographic image forming apparatus having a double-sided image forming function,
A first liquid cooling means disposed on the downstream side of the fixing means for fusing and fixing the toner image on the first surface of the transfer medium with heat in the image forming process, and for cooling the heated transfer medium; ,
When a toner image is formed on the second surface of the transfer medium in succession, the toner image is disposed on a transport path for guiding the transfer medium to the image forming process again to further cool the transfer medium. A cooling device comprising two liquid cooling means.   The first liquid cooling unit and / or the second liquid cooling unit include a liquid cooling type liquid cooling roller that cools the heat source by liquid circulation, and a conveyance pressure roller or conveyance pressure that presses the transfer medium against the liquid cooling roller. The cooling device according to claim 1, wherein the cooling device comprises a belt.   At least one of the liquid cooling means is provided with a plurality of the liquid cooling rollers, and each of the plurality of liquid cooling rollers is pressed against the liquid pressure roller corresponding to the liquid cooling roller. The cooling device according to claim 2, wherein the pressure is individually variable.   3. The cooling device according to claim 2, wherein a liquid cooling roller is provided separately on the conveying pressure belt for cooling the belt in contact with a surface that contacts the transfer medium. The second liquid cooling means liquid-cools the conveyance path cover of the reversing duplex unit for double-sided image formation, and thereby cools the transfer medium temporarily stopped on the conveyance path cover; and
A liquid-cooled upper surface cover that is provided at a transfer medium stationary position on the transport path cover so as to be movable toward the upper surface side of the transfer medium, and moves and contacts the upper surface of the transfer medium in a stationary state;
A liquid cooling type moving side cooling means for cooling the liquid cooling upper surface cover,
5. The cooling according to claim 1, wherein the upper surface of the transport path cover and the liquid-cooled upper surface cover contact and cool the stationary transfer medium from both sides. apparatus.   An image forming apparatus comprising the cooling device according to claim 1.

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