JP2014032262A - Sheet cooling device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate non-uniformity in surface temperature of a sheet having passed through a fixing device and prevent a sheet in a stack from being curled or corrugated due to a difference in water absorption between a center part and an end part of the sheet.SOLUTION: A cooling device 101 includes: a cooling belt 203 having a width larger than a width orthogonal to a conveyance direction of a sheet P, and conveying the sheet P having passed through a fixing device 100, in contact with at least one surface thereof; a heat sink 205 having a contact surface in contact with the cooling belt 203 to perform heat exchange; a water-cooling pipe 401 in contact with the heat sink 205 to allow liquid to flow therein; a cooling-water circulation device 404 for circulating cooling water in the water-cooling pipe 401; and a heat radiation part 402 for cooling the liquid circulated in the water-cooling pipe 401. A liquid passage of the water-cooling pipe 401 is formed so that the cooling water flows from a lateral center part to an end part of the heat sink 205.

Description

  The present invention relates to a sheet cooling apparatus for cooling a sheet and an image forming apparatus having the sheet cooling apparatus.

  In a conventional image forming apparatus using an electrophotographic system, first, a latent image formed on a photoconductor as an image carrier is developed to form a visible image, and the visible image (toner image) is electrostatically applied to a sheet. Use to transfer. Next, the transferred image is heated and pressed to fix it, thereby forming an image on the sheet.

  Conventionally, a roller fixing method has been adopted as a fixing device that performs such a fixing operation. In a roller fixing type fixing device, a pressure nip portion (fixing nip portion) is composed of a fixing roller heated by a built-in heat source such as a halogen heater and maintained at a predetermined temperature, and a pressure roller having elasticity pressed against the fixing roller. Form. An unfixed toner image on the surface of the sheet is thermally fixed by introducing the sheet into the pressure nip and nipping and conveying the sheet.

  In the fixing step by heating and pressing, heat is applied to the toner and the sheet, so that moisture inside the sheet evaporates after the pressure nip and the pressure nip.

  Here, a sheet-like paper that is most commonly used as a sheet is viewed at the fiber level. Paper is composed of short fibers entangled with each other, and moisture is contained inside or between the fibers, and the fibers and water form hydrogen bonds.

  However, as described above, when moisture inside the sheet evaporates, the hydrogen bond between the fiber and water is removed, and the hydrogen bond occurs between the fibers, so that deformation occurs inside the sheet. On the other hand, if the sheet is left unattended, it absorbs moisture from the surrounding environment, so that the hydrogen bonds between the fibers are separated again. However, there is no moisture between some of the fibers, which keeps the deformation. There are two types of deformation patterns, one that deforms due to the difference in expansion / contraction between the front and back of the sheet, and the other that occurs due to the difference in expansion / contraction between the center and the edge of the sheet.

  As described above, a phenomenon called “curl” in which the sheet is bent and a phenomenon called “waving” in which the sheet is wavy occur due to the change in the moisture content inside the sheet and the stress applied to the sheet.

  As a method for reducing deformation of the sheet due to heat and pressure in the fixing process, a configuration in which the sheet is cooled after the fixing process has been proposed (see Patent Document 1). In this patent document 1, a sheet cooling configuration using a belt pair having a heat sink inside a belt on one side is proposed.

JP 2009-181055 A

  However, the cooling mechanism that cools the sheet after the conventional fixing process can reduce deformation generated in the sheet due to cooling, but the cooling method causes temperature unevenness in the surface of the sheet. was there.

  For example, in the cooling configuration of Patent Document, a heat sink is provided in the heat exchange part inside the belt, and air is flowed in one direction by a fan from one side to cool the heat sink. The air feeding side has a high cooling effect on the heat sink because the temperature of the air is low, and conversely, the cooling effect on the heat sink is low on the side from which the air is discharged because the temperature of the air is high. As a result, a difference in the cooling effect on the belt sheet cooled by the heat sink occurs. Therefore, unevenness occurs in the surface temperature of the sheet due to the difference in cooling effect (see FIG. 6A).

  When temperature unevenness occurs on the surface of the sheet, the amount of water evaporated from the sheet becomes uneven within the surface of the sheet. The occurrence of unevenness in the amount of water causes a difference in the expansion / contraction rate within the surface of the sheet, which is a factor such as curling and undulation of the sheet. Further, when a large amount of sheets on which toner is fixed is stacked, the edge of the sheet that is in contact with the air absorbs moisture in the air, and the evaporated moisture can be immediately recovered. On the other hand, since it takes time to recover the moisture at the center of the sheet that is not in contact with air, there is a problem in that the amount of moisture is uneven in the surface of the sheet after passing.

  FIG. 3 shows a stack of 20 sheets discharged from the fixing device. The difference in water content between the edge of the top sheet and the center of the top sheet and the edge and top of the top sheet. The result of having measured the difference of the moisture content of the center part of the 10th sheet | seat from 1st is shown. 10 minutes after being discharged from the fixing device, the water content at the center of the top sheet and the water content at the center of the 10th sheet from the top are both at the end of the top sheet. It can be seen that it is less than the amount of water. This indicates that the end portion of the sheet is generally easier to cool than the center portion, and it can be said that the amount of water is reduced more in the center portion than in the end portion of the sheet.

  From the graph of FIG. 3, the center portion of the uppermost sheet in contact with the atmosphere recovers moisture in a short time, whereas the center portion of the tenth sheet from the top indicates the amount of water. It can be seen that it takes a long time to recover. Further, when 1000 sheets discharged from the fixing device are stacked, the water content at the end can be recovered, but the water content at the center is not recovered.

  As described above, in the conventional cooling method, since the sheet discharged from the fixing device has a large influence on the deformation of the sheet due to the change in the moisture content at the end and the center, there is a difference in the expansion / contraction ratio in the sheet surface. As a result, curling and undulation of the sheet could not be completely solved.

  SUMMARY OF THE INVENTION An object of the present invention is to improve sheet curling and undulation caused by unevenness in the surface temperature of a sheet after passing through a fixing device and a difference in moisture absorption between the central part and the edge part of the sheet when the sheets are stacked. That is.

  In order to achieve the above object, the present invention has a width in the width direction that is greater than the length in the width direction orthogonal to the sheet conveyance direction of the heated sheet, and conveys the sheet in contact with at least one surface of the sheet to be conveyed. A belt-like conveying means, a heat exchanging part having a contact surface that contacts the conveying means for heat exchange, a water cooling member that contacts the heat exchanging part and allows a liquid to flow inside, and an interior of the water cooling member In the sheet cooling device having a liquid circulation mechanism that circulates the liquid and a heat radiating unit that cools the liquid circulated inside the water cooling member, the liquid flows through the liquid cooling channel of the water cooling member. It forms so that it may flow from a width direction center part to an edge part.

  According to the present invention, the cooling effect on the sheet that has passed through the fixing device can be made larger at the center than at the end of the sheet. Thereby, the center part of the sheet | seat which is hard to cool compared with an edge part can be positively cooled, and the nonuniformity of the surface temperature of the sheet | seat after cooling can be reduced. Furthermore, the reduction in the amount of moisture at the center of the sheet, which takes time to recover the amount of moisture when stacked, can be made smaller than the reduction in the amount of moisture at the end of the sheet where the amount of moisture can be easily recovered. As a result, it is possible to improve sheet curling and undulation caused by unevenness in the surface temperature of the sheet after passing through the fixing device and the difference in moisture absorption between the central portion and the end portion of the sheet when the sheets are stacked. .

The fragmentary perspective sectional view showing the sheet cooling device concerning this embodiment. The cross-sectional view which shows the sheet | seat cooling device which concerns on this Embodiment. FIG. 6 is a diagram illustrating a difference in surface temperature of a sheet discharged from a fixing device. The fragmentary perspective sectional view which shows another sheet | seat cooling device which concerns on this Embodiment. Sectional drawing which shows the conventional cooling structure. The figure which showed the temperature change of the sheet | seat of the structure of the past and the structure of this invention. The figure which showed the temperature change of the sheet | seat of the structure of the past and the structure of this invention. The flowchart which shows operation | movement of a sheet | seat cooling device. The block diagram which shows the control structure of a sheet | seat cooling device. Sectional drawing which shows an electrophotographic printer.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in the following embodiments should be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions. Therefore, unless specifically stated otherwise, the scope of the present invention is not intended to be limited thereto.

  FIG. 10 is a cross-sectional view of the color electrophotographic printer 500, which is an example of an image forming apparatus including the sheet cooling apparatus according to the present embodiment, along the sheet conveyance direction. In this embodiment, the color electrophotographic printer is simply referred to as “printer”. Examples of the sheet include a paper sheet on which a toner image is formed, a plastic sheet, and a cloth. Specific examples of the sheet include plain paper, a resin sheet that is a substitute for plain paper, cardboard, and overhead projector.

  The printer 500 shown in FIG. 10 includes an image forming unit 510 for each color of Y (yellow), M (magenta), C (cyan), and Bk (black). Each image forming unit forms a toner image for each color to be formed on a sheet. In each image forming unit, a photosensitive drum 511 as an image carrier is charged in advance by a charging roller 512. Thereafter, a latent image is formed on the photosensitive drum 511 by the laser scanner 513. The latent image becomes a toner image by the developing device 514. The toner image on the photosensitive drum 511 is transferred to the intermediate transfer belt 531 serving as an intermediate transfer member in an overlapping manner.

  On the other hand, sheets P as recording materials are sent one by one from the feeding cassette 520 and fed to the registration roller pair 523. The registration roller pair 523 temporarily receives the sheet P, and when the sheet is skewed, corrects the skew and straightens it. The registration roller pair 523 sends the sheet P between the intermediate transfer belt 531 and the secondary transfer roller 535 in synchronization with the toner image on the intermediate transfer belt 531. The color toner images on the intermediate transfer belt 531 are collectively transferred onto the sheet P by a secondary transfer roller 535 as a transfer unit.

  Thereafter, the toner image T of the sheet P is fixed to the sheet P by being heated and pressed by the fixing device 100. After passing through the fixing device 100, the sheet P is cooled in a cooling device 101 as a sheet cooling device, and discharged to a discharge tray 565 face up (toner image is on the upper side).

  Next, a cooling device 101 as a sheet cooling device will be described with reference to FIGS. 1 and 2.

  The cooling device 101 includes receiving guide portions 201 and 202 that guide the sheet P that has passed through the fixing device. The sheet P is fed between the cooling belts 203 and 204 facing the front and back surfaces of the sheet P by the receiving guide portions 201 and 202, respectively.

  Each of the cooling belts 203 and 204 has a length in the width direction that is greater than the length in the width direction orthogonal to the sheet conveyance direction of the sheet P to be conveyed, and is a belt-like shape that conveys the sheet P in surface contact with the front and back surfaces. It is a conveying means. The center of the cooling belts 203 and 204 in the width direction coincides with the conveyance center of the sheet P in the width direction. Here, the configuration in which the belt-shaped conveying means is in surface contact with both surfaces of the sheet P is illustrated, but the configuration is not limited thereto, and a configuration in which the belt is conveyed in contact with at least one surface of the sheet may be used. .

  The cooling belts 203 and 204 may be made of a material having excellent heat conductivity, and may be any material that can form a thin plate such as a polyimide film, a nickel electroformed film, or a polyethylene film.

  The cooling device 101 includes a driving roller 206 that drives and circulates endless cooling belts 203 and 204, a tension roller 207 that stretches the belt, and a heat exchange unit that is disposed in an inner space of the cooling belt 203. A heat sink 205 is provided. Here, the cooling belt 203 on one surface side of the sheet is a belt that is driven to rotate, and includes a driving roller 206, a tension roller 207, and a heat sink 205. On the other hand, the cooling belt 204 on the other side of the sheet is a belt that rotates following the cooling belt 203 and includes a tension roller 207 and a backup roller 410 described later.

  When the sheet P is conveyed to the cooling device 101, the sheet P is nipped and conveyed between the cooling belts 203 and 204. As a result, the heat of the sheet P heated by the fixing device is transmitted to the cooling belt 203 and radiated through the heat sink 205.

  A plurality of backup rollers 410 for maintaining close contact between the cooling belt 203 and the cooling belt 204 are arranged inside the cooling belt 204. The heat sink 205 is a heat exchanging unit that performs heat exchange by contacting the inner surface of the cooling belt 203 with a contact surface having a width direction length substantially equal to the width direction length of the cooling belt 203. The heat sink 205 is formed of aluminum having a high heat dissipation effect. A water cooling pipe 401 is embedded inside the heat sink 205. The water-cooled pipe 401 is a water-cooled member that contacts the heat sink 205 and allows a liquid to flow from the center in the width direction to the end of the heat sink 205. Cooling water W as a liquid circulates inside the water cooling pipe 401, and the heat recovered from the heat sink 205 is exhausted by the heat radiating unit 402 outside the cooling device 101 to dissipate heat to the outside of the cooling device 101. I do.

As the cooling water W, water (H ₂ O) containing 20% of ethylene glycol is used. The heat radiating section 402 is cooled by sending air to the meandering water cooling pipe 401 by a fan 403. The heat dissipating unit 402 may be configured to be able to cool the cooling water W circulated through the water-cooled pipe 401, and is not limited to the configuration exemplified in this embodiment.

  A cooling water circulation device 404 as a liquid circulation mechanism for circulating the cooling water W inside the water cooling pipe 401 is disposed at the end of the water cooling pipe 401. In the cooling water circulation device 404, the supply path 405 and the circulation path 406 of the cooling water W are connected to a tank 408 provided with a water pump 407. The cooling water W is supplied to the cooling device 101 through the supply path 405 by the water pump 407, and the liquid cooled by the heat radiating unit 402 is circulated to the tank 408 through the circulation path 406. Cycle W. Here, the tank 408 can be attached to and detached from the main body of the cooling water circulation device 404, and water (liquid) can be replenished from a water supply port 408a opened at the upper part thereof.

  The cooling water W supplied from the supply path 405 to the inside of the cooling device 101 circulates in the direction of the arrow in the water cooling pipe 401 of the heat sink 205 in contact with the inner surface of the cooling belt 203. The water cooling pipe 401 forms a first water cooling unit 401A on one side in the width direction and a second water cooling unit 401B on the other side in the width direction so that the cooling water W flows from the center in the width direction to the end of the heat sink 205. Are unitized. Two water cooling units 401 A and 401 B formed by the water cooling pipe 401 are provided side by side in the width direction of the heat sink 205. The water cooling pipe 401 forming the two water cooling units 401A and 401B is embedded in the heat sink 205 from the center in the width direction perpendicular to the sheet conveying direction of the heat sink 205. The water cooling pipes 401 of the embedded water cooling units 401A and 401B each form a flow path from the center to the end in the sheet width direction, and then exit from the end of the heat sink 205 to the outside of the heat sink 205. Is arranged. At this time, heat is exchanged with the cooling water W inside the heat sink 205 in contact with the inner surface of the cooling belt 203.

  In this way, the liquid flow path of the water cooling pipe 401 is formed by the heat sink 205 so that the liquid flows from the center portion to the end portion in the width direction orthogonal to the sheet conveying direction of the heat sink 205. Therefore, the temperature Ta in the water-cooled pipe interior 401a at the center of the heat sink 205 is lower than the temperature Tb in the water-cooled pipe interior 401b at the end of the heat sink 205. Therefore, the temperature of the heat sink 205 is lower at the center than at the end. For this reason, the center part of the sheet P cooled via the cooling belt 203 is also cooled more than the end part.

  That is, the cooling effect on the sheet P that has passed through the fixing device 100 can be made larger at the center than at the end of the sheet P. Thereby, the center part of the sheet | seat P which is hard to cool compared with an edge part can be positively cooled, and the nonuniformity of the surface temperature of the sheet | seat P after cooling can be reduced.

  Further, the water-cooled pipe 401 coming out from the end of the heat sink 205 is spirally arranged inside the cooling belt 203 and is buried again in the heat sink 205 downstream in the sheet conveying direction. The spiral arrangement of the water cooling pipe 401 with respect to the heat sink 205 is repeatedly embedded from the upstream side to the downstream side in the sheet conveying direction. That is, the liquid flow path of the water cooling pipe 401 is formed by the heat sink 205 so that the liquid flows from the upstream portion to the downstream portion in the sheet conveying direction of the heat sink 205.

  Thereby, the cooling water W heat-exchanged with the heat sink 205 by the water cooling pipe inside 401b is supplied from the water cooling pipe inside 401a to the water cooling pipe inside 401c. For this reason, the temperature Tc of the water-cooled pipe interior 401c is higher than the temperature Ta of the water-cooled pipe interior 401a upstream in the sheet conveying direction. Therefore, by embedding the water cooling pipe 401 spirally arranged from the upstream in the sheet conveying direction to the downstream, it is possible to supply the cooling water W having a lower temperature upstream than in the downstream of the sheet conveying direction. become.

  Since the sheet P that has passed through the fixing device 100 and is sent to the cooling device 101 is cooled by the cooling device 101 and the temperature is lowered, the efficiency of heat exchange with the cooling belt 203 is gradually lowered. However, as described above, by forming the cooling water flow path (water cooling pipe 401) in a spiral shape, the temperature of the heat sink 205 on the upstream side in the sheet conveying direction can be made lower than that on the downstream side. Thereby, the sheet P can be cooled in a state where the temperature difference between the sheet P and the cooling belt 203 is the largest, that is, in a state where the efficiency of heat exchange is high.

  In addition, although this embodiment demonstrated the structure which circulates the cooling water W with the water cooling pipe which is a pipe-shaped member, it is not limited to this, The cooling water W can be supplied toward an edge part from a center part. Any configuration is acceptable. For example, the structure which forms a flow path as shown in FIG. 4 may be sufficient. The water-cooling member is provided by arranging two plate members whose ends are joined to each other in the width direction of the heat sink 205, and each of them as a first water-cooling unit 409A on one side in the width direction and a second water-cooling unit 409B on the other side in the width direction. It has become. Each plate member constituting the two water-cooling units 409A and 409B is embedded in the heat sink 205, and a flow path is formed from the center portion in the width direction toward the end portion. The cooling water W is circulated by 405 and the circulation path 406. For example, the cooling water W supplied to the central portion in the width direction in the supply path 405 flows from the flow path branched in the central part of the plate member toward the end, and is circulated through the circulation path 406. Like that. In addition, the joining to each plate member joins the supply path 405 to the upstream side in the sheet conveyance direction of each plate member, and joins the circulation path 406 to the downstream side in the sheet conveyance direction of each plate member. The water cooling member is a member that exchanges heat by contacting the heat sink 205. Further, the flow path of the cooling water W is formed in an 8-shaped shape including two circulation paths, and the two circulation paths are respectively formed in the heat sink 205 so that the cooling water W flows from the center portion to the end of the heat sink 205. You may make it circulate by contacting.

  Next, the effect of this embodiment will be described with reference to FIGS. FIG. 5 is a cross-sectional view of a conventional cooling device, and FIG. 6 is a diagram showing the measurement results of the surface temperature of the sheet immediately after passing through the cooling mechanism and 30 seconds after being discharged outside the apparatus when the conventional cooling mechanism is used. is there. FIG. 7 is a diagram showing measurement results of the sheet surface temperature immediately after passing through the cooling mechanism and 30 seconds after being discharged outside the apparatus when cooled using the cooling mechanism of the present embodiment.

  In the conventional cooling mechanism, the heat sink 205 is cooled by a fan 214 as shown in FIG. Since the air is cold on the blowing side of the fan 214, the cooling effect on the heat sink 205 is large. However, when the air passes through the narrow groove of the heat sink 205, the air gradually warms. The cooling effect is weak compared to the blowing side. That is, the cooling effect is large on one side in the sheet width direction, but the cooling effect is weaker on the other side than the one side described above. For this reason, a similar temperature distribution is reflected on the cooling belt cooled in contact with the heat sink 205, and further, the same is reflected on the surface temperature of the sheet. As a result, as shown in FIG. 6, the surface temperature of the sheet immediately after passing through the cooling mechanism rises from the fan blowing side to the fan blowing side.

  Further, when the sheet has been discharged out of the machine and the time has passed, the central portion is less likely to be cooled than the end portion of the sheet as described above. Will result in large variations. For this reason, the moisture evaporation amount of the sheet also varies in the plane, and thus deformation such as corrugation of the sheet occurs.

  In contrast, in the present embodiment, the heat sink 205 is cooled from the center toward the end, so the surface temperature of the sheet immediately after being cooled by the cooling belt is lower in the center than at the end. Become. In this way, the temperature at the center of the sheet surface immediately after discharge is actively lowered compared to the edges, thereby suppressing variations in temperature within the sheet surface due to the fact that the temperature at the center of the sheet is less likely to be cooled than the edges. can do. As a result, as shown in FIG. 7, the surface temperature of the sheet 30 seconds after discharge can be made more uniform than in the case of using a conventional cooling device. This also allows the sheet surface to expand and contract in the same way at the center and end portions, so that it is possible to further reduce sheet curling and undulation.

  Next, the sheet cooling operation after fixing of the electrophotographic printer 500 will be described using the flowchart shown in FIG. 8 and the apparatus block shown in FIG.

  When the standby operation starts, the main motor M starts rotating at a speed about half the normal speed (half speed) in response to a command from the CPU (control means) 420 via the motor driver 421 (S2) (S2). ), Conveyance and circulation of the cooling belt 203 are started. At this time, the cooling belt 204 starts driven rotation due to sliding friction between the cooling belt 203 and the heat sink 205.

  The heater 110a and the pressure heater 111a for heating the heating roller 110 and the pressure roller 111 of the fixing device 100 are energized through a heater driver 422 in response to a command from the CPU 420, and temperature adjustment of each roller is started. (S3). When the image forming job of the electrophotographic printer 500 is started (S4), the main motor M rotates at full speed to convey and circulate the cooling belts 203 and 204 at a predetermined speed (for example, 600 mm / s) (S5).

  The sheet P is sandwiched between the cooling belts 203 and 204 that are in planar contact, and the front and back surfaces of the sheet P are conveyed in surface contact with the cooling belts 203 and 204. Due to this surface contact, the heat of the sheet P is transmitted to the cooling belt 203, and is transferred to the heat sink 205 at the contact portion between the cooling belt 203 and the heat sink 205. Liquid (cooling water W) is circulated through the heat sink 205 by a water pump 407 driven by a pump driver 423. The heat sink 205 exchanges heat with the water-cooled pipe 401 to finally exhaust heat from the heat radiating unit 402. After passing through the fixing device 100 and passing through the cooling device 101, the sheet P that has risen in temperature is discharged in a state where the central portion is cooled compared to the end portion in the sheet width direction (the central portion is about 35 ° C.). ).

  When the image forming job ends (S6), the rotation of the main motor M is stopped (S7), and then all the image forming jobs of the electrophotographic printer 500 are stopped.

  As described above, according to the present embodiment, the cooling effect on the sheet that has passed through the fixing device can be made larger at the center than at the end of the sheet. Thereby, the unevenness of the surface temperature of the sheet after cooling can be reduced by positively cooling the central part of the sheet that is harder to cool than the end part. Furthermore, the reduction in the amount of moisture at the center of the sheet, which takes time to recover the amount of moisture when stacked, can be made smaller than the reduction in the amount of moisture at the end of the sheet where the amount of moisture can be easily recovered. As a result, it is possible to improve sheet curling and undulation caused by unevenness in the surface temperature of the sheet after passing through the fixing device and the difference in moisture absorption between the central portion and the end portion of the sheet when the sheets are stacked. .

  In the above-described embodiment, four single-color image forming units having different colors are used to form a color image. However, the number used is not limited, and may be set as necessary. It ’s fine.

  In the above-described embodiment, the printer is exemplified as the image forming apparatus, but the present invention is not limited to this. For example, the image forming apparatus may be another image forming apparatus such as a copying machine or a facsimile machine, or another image forming apparatus such as a multi-function machine combining these functions. The image forming apparatus is not limited to an image forming apparatus using an intermediate transfer member, and uses a sheet carrier and sequentially transfers toner images of respective colors onto a sheet carried on the sheet carrier. Also good. The same effect can be obtained by applying the present invention to these image forming apparatuses.

P ... Sheet 100 ... Fixing device 101 ... Cooling device 110 ... Heating roller 110a ... Heating heater 111 ... Pressure roller 111a ... Pressure heater 203, 204 ... Cooling belt 205 ... Heat sink 206 ... Drive roller 207 ... Tension roller 401 ... Water cooling pipe 401a, 401b, 401c ... Inside water-cooled pipe 402 ... Radiator 403 ... Fan 404 ... Cooling water circulation device 405 ... Supply path 406 ... Circulation path 407 ... Water pump 408 ... Tank 409A, 409B ... Water-cooling unit 410 ... Backup roller 420 ... CPU
421 ... Motor driver 422 ... Heater driver 423 ... Pump driver 500 ... Electrophotographic printer 510 ... Image forming unit

Claims (5)

A belt-like conveying means that has a width in the width direction that is greater than the length in the width direction orthogonal to the sheet conveying direction of the heated sheet, and conveys the sheet in contact with at least one surface of the conveyed sheet;
A heat exchanging part having a contact surface that contacts the conveying means and exchanges heat;
A water-cooling member that contacts the heat exchanging part and allows a liquid to flow inside;
A liquid circulation mechanism for circulating a liquid inside the water cooling member;
A heat dissipating part for cooling the liquid circulated through the water cooling member;
In a sheet cooling apparatus having
The sheet cooling apparatus according to claim 1, wherein the liquid flow path of the water cooling member is formed so that the liquid flows from a central portion in the width direction of the heat exchange portion to an end portion.   2. The sheet cooling according to claim 1, wherein the liquid flow path of the water cooling member is formed in the heat exchange unit so that liquid flows from an upstream part to a downstream part in a sheet conveyance direction of the heat exchange part. apparatus.   The sheet cooling apparatus according to claim 1, wherein the water cooling member is a pipe-shaped member.   The water cooling member forms a first water cooling unit on one side in the width direction and a second water cooling unit on the other side in the width direction so that the liquid flows from the center in the width direction to the end of the heat exchange unit. The sheet cooling device according to any one of claims 1 to 3, wherein the two water cooling units are provided side by side in a width direction of the heat exchange unit.   5. The image forming unit that forms a toner image on the sheet, a fixing device that fixes the toner image formed on the sheet by heating, and the sheet that has passed through the fixing device is cooled. An image forming apparatus comprising: the sheet cooling device according to claim 1.

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