JP2012082043A - Sheet reversing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress temperature rise within a reversing carrying passage and prevent an image abnormality of paper caused by temperature rise.SOLUTION: An ADU reversing unit 201 reversing and outputting paper received from a predetermined paper carrying direction includes: a device body part 21 having a U-turn guide part 24 in a direction approximately orthogonal to the paper carrying direction and reversing the paper; a carrying drive part 23 drawing the paper into the device body part 21 and sending out the paper after it has been reversed in the U-turn guide part 24; and a partition plate 22 provided between the U-turn guide part 24 and the carrying drive part 23 and partitioning inside of the device body part 21. The structure of the partition plate 22 can block transmission of heat generated in the carrying drive part 23 to the U-turn guide part 24.

Description

  The present invention relates to a monochrome or color printer for forming an image on both sides of a predetermined sheet based on a duplex printing mode, a sheet reversing apparatus and an image forming apparatus applicable to these copying machines, multifunction machines, printing apparatuses, and the like. It relates to the device.

  In recent years, monochrome printers and color printers, copiers, multifunction peripherals, printing apparatuses and the like (hereinafter referred to as image forming apparatuses) are often used. Among image forming apparatuses, a paper reversing device is provided, and an image is formed on one side of a predetermined paper based on the duplex printing mode, and then the front and back sides of the paper are reversed by the paper reversing device to form an image on the other side. A device equipped with is used.

  A monochrome image forming apparatus having a duplex printing function includes a paper feed tray, an image forming unit, a fixing unit, and an automatic paper reversing / conveying unit (hereinafter referred to as an ADU reversing unit). The ADU reversing unit has a function of automatically reversing the paper after image formation in a paper conveyance direction different from the paper conveyance direction during image formation.

  For example, when the double-sided printing mode is set in the image forming apparatus, the image forming unit forms a black toner image on one side of the paper fed from the paper feed tray based on the image data. In the image forming unit, an electrostatic latent image based on monochrome image data is formed on a photosensitive drum uniformly charged by a charger by a scanning exposure unit using a polygon mirror or the like.

  The electrostatic latent image on the photosensitive drum is developed by a developing device. Such charging, exposure, and development are performed, and the toner image formed on the photosensitive drum is transferred onto a desired sheet by the transfer unit. The toner image transferred onto a predetermined sheet is fixed by the fixing unit. The sheet after fixing is turned upside down by the ADU inversion unit, and the sheet after turning upside down is fed again to the image forming unit. In the image forming unit, a black toner image is formed on the other side of the re-fed paper based on the image data. The sheet on which the toner image is formed on the other side is fixed by the fixing unit. The fixed sheet is discharged. As a result, black and white images based on the image data can be formed on the front and back of a predetermined sheet. Here, an example of the internal configuration of the ADU inversion unit will be described.

  FIG. 12 is a schematic side view showing an example of the internal configuration of the ADU reversing unit 200 according to the conventional example. An ADU reversing unit 200 shown in FIG. 12 includes an apparatus main body unit 21, a conveyance driving unit 23, and a U-turn guide unit 24. The U-turn guide part 24 has a sheet conveying structure having an arc cross section, for example, a duct structure. The apparatus main body 21 has a box shape (box shape) including an arc side surface portion (hereinafter referred to as a side frame 21a) along the sheet conveying structure of the U-turn guide portion 24. The conveyance drive unit 23 includes pull-in rollers 13 and 14, pull-out rollers 15 and 16, a feed-out roller 31, a reception roller 32, a motor 33, and a spur gear mechanism 305.

  According to the function of the ADU reversing unit 200, when the motor 33 rotates in a predetermined direction when the duplex printing mode is executed, the rotational force of the motor 33 rotates the drawing rollers 13 and 14 via the spur gear mechanism 305. As a result, the drawing rollers 13 and 14 are driven in a predetermined direction, and the drawing rollers 13 and 14 draw the fixed sheet P received from a circulation refeed path (not shown) into the apparatus main body 21.

  In the apparatus main body 21, the feed roller 31 is driven by rotating a motor (not shown) so as to send the paper P through the U-turn guide 24 in a paper transport direction substantially orthogonal to the paper transport direction. The paper P that is turned upside down from the U-turn guide portion 24 is received by the receiving roller 32 as a motor (not shown) rotates.

  The drawing rollers 15 and 16 are driven by the rotational force of the motor 33 and the like being transmitted through the spur gear mechanism 305. By driving the drawing rollers 15 and 16, the sheet P that has been turned upside down is sent out from the inside of the apparatus main body 21 to a refeeding path (not shown). As a result, the front and back of the paper P are converted by reversing the left and right sides of the paper P with respect to the paper transport direction before the paper P after image formation is fed again.

  In relation to an image forming apparatus having this type of paper reversing function, Patent Document 1 discloses an image forming apparatus. The image forming apparatus includes a paper feeding unit, a paper discharge unit, a main conveyance path, an image forming unit, a refeed conveyance path, and a front / back conversion unit. The main transport path transports the paper fed from the paper feed unit to the paper discharge unit. The image forming unit is provided in the middle of the main conveyance path and forms an image on one side of the sheet. The re-feed conveyance path re-feeds the paper on which the image is formed on one side by the image forming unit to the image forming unit again. On the premise of this, the front / back conversion means is provided on the refeed conveyance path, and the front / back conversion means converts the front and back of the paper by reversing the left and right sides of the paper with respect to the paper transport direction. I made it. If the image forming apparatus is configured in this way, the configuration of the front / back conversion means can be simplified and the space can be saved.

Japanese Patent Application Laid-Open No. Sho 61-111244 (Page 4 FIG. 2)

Incidentally, the image forming apparatus provided with the ADU reversing unit 200 according to the conventional example as found in Patent Document 1 has the following problems.
i. In general, when an image is formed on one side of the paper P by the image forming unit when the double-sided printing mode is executed, the paper P becomes heated due to the heat treatment received during the fixing. The paper P is turned upside down by the ADU reversing unit 200 while being heated. Accordingly, the sheet P that is still heated passes through the U-turn guide portion 24, so that the heat is easily trapped inside the sheet conveying structure. The problem is that as the large number of double-sided printing modes are executed, the thermal fog phenomenon inside the U-turn guide unit 24 becomes more significant.

  ii. Further, according to the ADU reversing unit 200 shown in FIG. 12, a method of reversing the paper P one by one without taking an integration (stacking) function inside the apparatus main body 21 is adopted. By not having an accumulation (stacking) function, it is possible to configure a sheet reversing device having a relatively thin box shape.

  However, from the viewpoint of effective use of space, a motor for driving the delivery roller 31, a motor for driving the reception roller 32, and a motor for driving the drawing rollers 15 and 16 are provided inside the thin box-shaped device body 21. There is a problem that heat generated by the motor 33 and the like is transmitted to the U-turn guide portion 24.

  iii. There is a concern that the heat generated by the motor 33 or the like described above is added to the heat trapped inside the U-turn guide portion 24, and the temperature inside the U-turn guide portion 24 further increases. When the paper P after image formation passes through the U-turn guide portion 24 that has been heated in this manner and curved in an arc shape, the paper P rubs against the inner wall of the U-turn guide portion 24 (hereinafter also referred to as a reverse conveyance path). Therefore, there is a concern that the toner agent melts and image abnormality such as streaks occurs in the image.

  SUMMARY OF THE INVENTION Accordingly, the present invention solves the above-described problem, and is capable of suppressing a temperature increase in the reversing conveyance path and preventing a sheet image abnormality caused by the temperature increase. An object of the present invention is to provide an image forming apparatus.

  In order to solve the above-described problem, a sheet reversing device according to claim 1 is provided with a sheet conveying structure having an arcuate cross section in the sheet reversing device that outputs the sheet member received from a predetermined sheet conveying direction by reversing the front and back. An apparatus main body having a reversal conveyance path and having a horizontal conveyance section for conveying the sheet member in the horizontal direction to reverse the sheet member; a sheet conveyance structure of the apparatus main body; and the horizontal conveyance section; And a partition member for partitioning the inside of the apparatus main body.

  According to the sheet reversing device of the first aspect, when the sheet member received from the predetermined sheet conveying direction is reversed and output, the apparatus main body portion sets the reversing conveying path in a direction substantially orthogonal to the sheet conveying direction. Hold the sheet member upside down. The conveyance drive unit pulls the sheet member into the apparatus main body and sends out the sheet member after being reversed on the reverse conveyance path. On the premise of this, a partition member is provided between the reverse conveyance path and the conveyance drive unit, and is configured to partition the inside of the apparatus main body. With this configuration of the partition plate, it is possible to block the heat generated in the transport driving unit from propagating to the reverse transport path.

  A sheet reversing device according to a second aspect of the present invention is the sheet reversing device according to the first aspect, wherein the reversing conveyance path has a sheet conveying structure having a circular arc cross section, and the apparatus main body is an arc side surface along the sheet conveying structure of the reversing conveying path The device main body is formed with a space region surrounded by the reversal conveyance path, the partition member, and a circular arc side surface of the device main body. is there.

  According to a third aspect of the present invention, the sheet inverting apparatus according to the second aspect is characterized in that an opening for air circulation is provided in a circular arc side surface portion of the apparatus main body.

  According to a fourth aspect of the present invention, there is provided the sheet inverting apparatus according to the third aspect, wherein the opening is provided on each of the sides facing each other at the arc side surface portion of the apparatus main body.

  According to a fifth aspect of the present invention, in the fourth aspect, the sheet inverting device includes a cooling fan attached to the opening on one side or the opening on both sides.

  A sheet reversing device according to a sixth aspect of the present invention includes the conveyance driving unit according to the first aspect, wherein the sheet reversing device includes a conveyance driving unit that pulls the sheet member into the apparatus main body and sends the sheet member that is reversed upside down in the reversal conveyance path. A first sheet conveying unit that pulls the sheet member received from the sheet conveying direction into the apparatus main body and sends the sheet member in a direction substantially orthogonal to the sheet conveying direction and conveys the sheet member into the reverse conveying path; A second sheet conveying unit that pulls out the sheet member from the reversing conveyance path and sends out the sheet member that has been turned upside down from the inside of the apparatus main body to convey the sheet member in a predetermined sheet conveying direction; And a driving unit for driving the motor.

  A sheet reversing device according to a seventh aspect of the present invention is the sheet reversing device according to the first aspect, wherein a cooling pleat member is provided on the partition member side of the reverse conveying path having the sheet conveying structure having an arcuate cross section. Is.

  The image forming apparatus according to claim 8, comprising: an image forming unit that forms an image on a predetermined sheet member; and a sheet reversing unit that reverses the sheet member formed by the image forming unit. The unit is configured by any one of the sheet reversing devices according to claims 1 to 7, or a combination of these sheet reversing devices.

  According to the image forming apparatus of the eighth aspect, since any one of the sheet reversing devices according to the present invention is provided, an increase in temperature at the sheet reversing portion can be suppressed. Therefore, it is possible to prevent an image abnormality of the sheet member due to the temperature rise.

  According to the sheet reversing device according to claim 1, the reversing conveying path provided with the sheet conveying structure having an arcuate cross section and the horizontal conveying unit that conveys the sheet member in the horizontal direction, and the device for reversing the sheet member A main body is provided, and a partition member is provided between the sheet transport structure and the horizontal transport unit, and the partition member is configured to partition the apparatus main body.

  With this configuration, the partition member can block the heat generated in the conveyance driving unit from propagating to the sheet conveyance structure having an arcuate cross section. Thereby, since the temperature rise in the said sheet conveyance structure can be suppressed, it becomes possible to prevent the image abnormality of the sheet member caused by the temperature rise.

  According to the sheet reversing device according to the second aspect, the space region forms an air heat insulating region between the reversing conveyance path and the conveyance driving unit.

  According to the sheet reversing device according to claim 3, air can be naturally circulated through the opening in the space region surrounded by the reversing conveyance path, the partition member, and the arc side surface portion of the device main body, and the space The cooling effect of the area can be enhanced.

  According to the sheet reversing device of the fourth aspect, air can be naturally circulated to the space region through the mutual opening, and the cooling effect of the space region can be further enhanced.

  According to the sheet reversing device according to claim 5, when a cooling fan is attached to the opening on one side, external air is forcibly blown into the space region through the one opening, and the other opening is opened. By forcibly discharging the warm air from the space area through the section, the warm air in the space area can be exchanged with the external air, and the space area can be forcibly cooled.

  According to the sheet reversing apparatus of the sixth aspect, the first sheet conveying unit that draws the sheet member into the apparatus main body and the second sheet conveying unit that sends out the sheet member that has been reversed in the reverse conveying path are driven. The partition member can block the heat generated in the drive unit from propagating to the reverse conveyance path. Thereby, since the temperature rise in the reverse conveyance path can be suppressed, it is possible to prevent the image abnormality of the sheet member due to the temperature rise.

  According to the sheet reversing device of the seventh aspect, the heat hidden in the reversing conveyance path is diffused by the cooling pleat member into the space region surrounded by the reversing conveyance path, the partition member, and the arc side surface portion of the apparatus main body. become able to.

  According to the image forming apparatus of the eighth aspect, the sheet inverting unit that reverses the image-formed sheet member is provided, and the sheet inverting unit includes any one of the sheet inverting apparatuses according to the present invention, or these These sheet reversing devices are combined.

  With this configuration, the temperature rise at the sheet reversing portion can be suppressed, so that it is possible to prevent image abnormality of the sheet member due to the temperature rise. As a result, it is possible to provide a highly reliable color image forming apparatus equipped with a duplex printing mode.

1 is a schematic diagram illustrating a configuration example of an image forming apparatus 100 as an embodiment according to the present invention. It is the schematic on the side surface which shows the example of an internal structure of the ADU inversion unit 201 as a 1st Example. FIG. 6 is a schematic side view illustrating a configuration example (No. 1) of the transport driving unit. FIG. 6 is a schematic diagram on the front side showing a configuration example (No. 2) of the transport driving unit; FIG. 5 is a perspective view showing an example of attaching the partition plate 22 of the ADU reversing unit 201. FIG. 6 is a schematic view seen from the bottom showing an operation example (No. 1) of the ADU reversing unit. (A) And (B) is the schematic seen from the side surface which shows the operation example (the 2) of the ADU inversion unit 201. FIG. FIG. 6 is a schematic view seen from the upper surface showing an operation example (No. 3) of the ADU reversing unit. It is the schematic on the side surface which shows the example of an internal structure of the ADU inversion unit 202 as a 2nd Example. It is the schematic of the side surface which shows the example of an internal structure of the ADU inversion unit 203 as a 3rd Example. It is the schematic of the side surface which shows the example of an internal structure of the ADU inversion unit 204 as a 4th Example. It is the schematic on the side surface which shows the example of an internal structure of the ADU inversion unit 200 concerning a prior art example.

  Hereinafter, a sheet inverting device and an image forming apparatus according to embodiments of the present invention will be described with reference to the drawings. An image forming apparatus 100 shown in FIG. 1 includes a sheet reversing device according to the present invention, and is a monochrome or color printer that forms images on both sides of a predetermined sheet member (hereinafter referred to as paper) based on a duplex printing mode. The present invention can be applied to these copying machines and multifunction machines. The sheet member includes plain paper, cardboard, thin resin sheets, sealed letters, labels, postcards, and the like (hereinafter simply referred to as paper). The image forming apparatus 100 includes an apparatus housing 101. Nearly the center of the apparatus housing 101 is provided with an automatic paper reversing / conveying unit (Auto Duplex Unit: hereinafter referred to as an ADU reversing unit 20) that constitutes an example of a sheet reversing unit so as to reverse the paper P after image formation. Operate. The ADU reversing unit 20 uses the sheet reversing device according to the present invention.

  Around the ADU reversing unit 20, a paper feed unit 1, a paper feed path 10, an image forming unit 6, a fixing unit 8, a paper discharge path 18, a circulation refeed path 26 and a refeed path 27 are provided. The sheet feeding unit 1 has sheet feeding trays 1 a and 1 b and is disposed below the ADU reversing unit 20. The paper feed tray 1a has a feeding roller 2a for storing paper P of a predetermined size. The paper feed tray 1b has a feeding roller 2b, and stores paper P of a predetermined size. For example, when the paper feed tray 1 a is selected, the feeding roller 2 a rotates and operates to feed the paper P from the paper feed tray 1 a to the paper feed path 10.

  In this example, the paper feed path 10 is disposed on the upstream side of the image forming unit 6 and along the right wall surface inside the apparatus housing 101. The paper feed path 10 includes transport rollers 3 a and 3 b, a transport roller 4, and a registration roller 5. The paper P fed out to the paper feed path 10 is conveyed by the conveyance rollers 3 a and 3 b and the conveyance roller 4 and reaches the registration roller 5. The sheet P waits at the position of the registration roller 5 and is fed to the image forming unit 6 at a predetermined timing.

  The image forming unit 6 is disposed between the registration roller 5 and the fixing unit 8. The image forming unit 6 forms an image on the paper P at a predetermined timing. Although not shown, the image forming unit 6 includes a photosensitive drum, a developing device, a transfer device, a writing unit, a cleaning unit, and the like. For example, when the image forming apparatus 100 forms a color printer, a tandem electrophotographic color printer engine is used for the image forming unit 6. When configuring a monochrome printer, an electrophotographic monochrome printer engine is used.

  The paper discharge path 18 includes the conveyance belt 7 and the paper discharge roller 9, and is disposed on the downstream side of the image forming unit 6. The conveyance belt 7 is disposed on the downstream side of the image forming unit 6 and conveys the paper P after image formation from the image forming unit to the fixing unit 8. The fixing unit 8 is disposed between the conveyance belt 7 and the paper discharge roller 9 and fixes the paper P after image formation. The fixing unit 8 is provided with a heating roller, and heats and fixes the toner image transferred to the paper P after image formation. The sheet P after the fixing process is heated. The paper discharge roller 9 is disposed on the downstream side of the fixing unit 8 and discharges the fixed paper P to the outside.

  The circulation refeed path 26 is branched from the paper discharge path 18 and is disposed at a position along the left wall surface inside the apparatus housing 101. The circulation refeeding path 26 has transport rollers 11 and 12 and is connected to the ADU reversing unit 20. When the double-sided printing mode is set in the circulation refeed path 26, the fixed sheet P branched from the paper discharge path 18 is guided to the ADU reversing unit 20 via the transport rollers 11 and 12. To work.

  The ADU reversing unit 20 operates to reverse the paper P after image formation (fixing) received from the circulation refeed path 26 (predetermined paper transport direction). The ADU reversing unit 20 has an apparatus main body 21 and a conveyance driving unit 23. A conveyance driving unit 23 is provided inside the apparatus main body 21. The transport driving unit 23 includes pull-in rollers 13 and 14 that constitute an example of a horizontal transport unit, pull-out rollers 15 and 16, a feed roller 31, a receiving roller 32, and the like, and transports paper in the horizontal direction. To work. The conveyance drive unit 23 operates to draw the paper P into the apparatus main body 21 and to send out the paper P that has been turned upside down by the U-turn guide unit 24. In the figure, Y and Z are the sheet conveying directions.

  A refeed path 27 having a loop roller 17 is connected to the ADU reversing unit 20. The refeed path 27 is connected to the feed path 10 in a time-sharing manner so that the paper P that has been turned upside down by the ADU reversing unit 20 is fed again to the image forming unit 6 via the loop roller 17. Operate. These constitute the image forming apparatus 100.

  Next, an example of the internal configuration of the ADU inverting unit 201 as the first embodiment will be described with reference to FIG. The ADU reversing unit 201 shown in FIG. 2 reverses the paper P after image formation received from the circulation refeed path 26 (sheet transport direction; hereinafter referred to as paper transport direction Y) shown in FIG. It operates to output to 6. X and Z in the figure are the sheet conveyance direction (hereinafter referred to as the sheet conveyance direction).

  The ADU reversing unit 201 includes an apparatus main body 21, a partition plate 22, a conveyance driving unit 23, and a U-turn guide unit 24. The U-turn guide portion 24 has a sheet conveying structure having an arc cross section. The apparatus main body 21 has a housing shape (box shape) including an arc side surface portion along the sheet conveyance structure of the U-turn guide portion 24. The apparatus main body 21 has a U-turn guide 24 in the paper transport direction X that is substantially orthogonal to the paper transport direction Y, and reverses the paper P.

  In this example, a partition plate 22 that constitutes an example of a partition member is provided between the U-turn guide portion 24 and the conveyance drive portion 23, and is configured to partition the inside of the apparatus main body portion 21. The partition plate 22 is disposed between the side frames 21a and 21b in the apparatus main body 21 (see FIG. 4). For the partition plate 22, for example, a metal plate having a length L, a height H, and a thickness t is used. The partition plate 22 is attached and fixed inside the apparatus main body 21 by electric welding, screwing, or the like. In addition to the metal plate, a composite plate having a heat insulating structure may be used as the partition member.

  A space region surrounded by the U-turn guide portion 24, the partition plate 22, and the arc side surface portion of the device main body 21 is formed inside the device main body 21. This space region forms an air insulation region between the U-turn guide part 24 and the transport driving unit 23. By forming the air insulation region, the temperature rise of the U-turn guide portion 24 can be prevented.

  The partition plate 22 may be anywhere between the apparatus main body portion 21 where the motor or the like serving as a heating element is disposed and the U-turn guide portion 24 as long as the U-turn guide portion 24 is difficult to be heated. In this way, the partition plate 22 provided between the U-turn guide portion 24 and the straight portion of the apparatus main body portion 21 conveys the U-turn guide portion 24 and the like bent in a U-shape that causes image abnormality. Since the temperature rise in the path portion can be prevented, image abnormality can be prevented.

  Subsequently, a configuration example of the transport driving unit 23 will be described with reference to FIGS. 3 and 4. In addition to the pull-in rollers 13 and 14 and the pull-out rollers 15 and 16 constituting the conveyance drive unit 23, the apparatus main body unit 21 shown in FIG. 3 includes a motor 33 and a spur gear mechanism 305 having a predetermined reduction ratio. ing.

  In this example, the drawing roller 13 includes a driving roller 13 a and a driven roller 13 b for drawing the paper P received from the circulation refeeding path 26 into the apparatus main body 21. The driving roller 13 a is provided with a rotating shaft 301, and a driving gear 302 is attached to the rotating shaft 301. The motor 33 is attached to the side opposite to the U-turn guide part 24 side. For example, a DC motor is used as the motor 33.

  The motor 33 has a rotating shaft 303, and a motor gear 304 is attached to the rotating shaft 303. The motor gear 304 is engaged with the spur gear mechanism 305. The spur gear mechanism 305 is engaged with the drive gear 302 of the drive roller 13a. When the motor 33 rotates in a predetermined direction, the rotational force of the motor 33 rotates the drive roller 13a via the spur gear mechanism 305. Thereby, the drawing roller 13 can be driven in a predetermined direction. The drawing roller 14 is configured in the same manner as the drawing roller 13.

  The drawing roller 15 is composed of a driving roller 15a and a driven roller 15b for sending out the paper P that has been turned upside down from the inside of the apparatus main body 21 and transporting it to the refeed path 27. Since the mechanism and method for transmitting to the drive roller 15a are configured in the same manner as the pull-in roller 13, the description thereof is omitted. The drawing roller 16 is configured in the same manner as the drawing roller 15.

  When the drawing rollers 13 and 14 and the drawing rollers 15 and 16 are independently driven, three other motors corresponding to the motor 33 are provided inside the apparatus main body 21. When the two drawing rollers 13 and 14 are simultaneously driven and the two drawing rollers 15 and 16 are simultaneously driven, two motors are reduced. When driving the drawing rollers 13 and 14 and the drawing rollers 15 and 16 simultaneously, the number of motors is reduced to one.

  The apparatus main body 21 shown in FIG. 4 is provided with arcuate side surface portions (hereinafter referred to as side frames 21a and 21b) on both sides of the U-turn guide portion 24, and is transported to an internal region defined by the side frames 21a and 21b. A drive unit 23 is provided, and motors 34 and 35 are disposed in addition to the feed roller 31 and the reception roller 32 constituting the transport drive unit 23.

  In this example, the feed roller 31 includes a driving roller 31a and a driven roller 31b, and feeds the paper P in the paper transport direction X substantially orthogonal to the paper transport direction Y and transports it into the U-turn guide portion 24. The The driving roller 31 a is provided with a rotating shaft 311, and a driving gear 312 is attached to the rotating shaft 311. The motor 34 is attached inside the apparatus main body 21 along the U-turn guide 24. For example, a DC motor is used as the motor 34.

  The motor 34 has a rotation shaft 313, and a motor gear 314 is attached to the rotation shaft 313. The motor gear 314 is engaged with the drive gear 312. When the motor 34 rotates in a predetermined direction, the rotational force of the motor 34 is transmitted to the drive gear 312 to rotate the drive roller 13a. The motor 34 can drive the feed roller 31 in a predetermined direction.

  The receiving roller 32 includes a driving roller 32a and a driven roller 32b in order to receive the paper P that is turned upside down from the U-turn guide 24. The receiving roller 32 transmits the motor rotational force of the motor 35 to the driving roller 32a. Since the mechanism and the method thereof are configured in the same manner as the feeding roller 31, the description thereof is omitted. The drawing rollers 13 and 14 and the delivery roller 31 described above constitute a first sheet conveying unit, and the receiving roller 32 and the drawing rollers 15 and 16 constitute a second sheet conveying unit. Thus, a conveyance driving unit 23 that drives the first and second sheet conveying units is configured.

  Next, an example of attaching the partition plate 22 of the ADU reversing unit 201 will be described with reference to FIG. The partition plate 22 illustrated in FIG. 5 is disposed between the U-turn guide unit 24 and the transport driving unit 23. The partition plate 22 is configured to partition the inside of the apparatus main body 21 with good airtightness. For the partition plate 22, for example, a metal plate having a length L, a height H, and a thickness t is prepared. The partition plate 22 is attached so as to divide the conveyance driving unit 23 provided with the drawing rollers 13 and 14, the drawing rollers 15 and 16, and the motors 33 to 35, and the sheet conveyance inner side of the U-turn guide unit 24 having an arc-shaped cross section. It is done.

  For example, in a state where the partition plate 22 is erected from the bottom of the device main body 21, the upper part of the partition plate 22 is the top plate of the device main body 21, the lower part is the bottom of the device main body 21, and the right side thereof Are fixed to one side wall of the apparatus main body 21 and the left side is fixed to the other side wall of the apparatus main body 21. The partition plate 22 is attached to the inside of the apparatus main body 21 by electric welding, screwing, or the like. In addition to the metal plate, a composite plate having a heat insulating structure may be used as the partition member.

  In addition, regarding the attachment of the partition plate 22, when a welding method cannot be taken, the partition plate 22 may be attached to the apparatus main body 21 after attaching an endless rubber packing around the partition plate 22. . In that case, L-shaped parts that are supported from both sides of the partition plate 22 may be applied to the left and right, and fixed with screws so as to be pressed from both sides.

  Next, with reference to FIGS. 6 to 8, operation examples (Nos. 1 to 3) of the ADU inversion unit 201 will be described. In this example, after the image is formed on the surface of the paper P by the image forming unit 6, the fixing process is performed, and the fixed paper P is conveyed to the circulation refeed path 26, and is sent from the circulation refeed path 26 to the ADU reversing unit. It is assumed that the paper P is drawn into 201 and the paper P after being turned upside down by the U-turn guide unit 24 is sent out to the refeed path 27 and the image forming unit 6 forms an image on the paper P after being turned upside down. To explain. In the figure, the white arrow is the conveyance direction of the paper P.

  Under these operating conditions, in the ADU reversing unit 201 viewed from the bottom surface side of the apparatus main body 21 shown in FIG. 6, the paper P conveyed from the circulation refeed path 26 (paper conveyance direction Y) It is taken into the ADU reversing unit 201 from the bottom side of the unit 21. At this time, in the ADU reversing unit 201, the nip between the driving roller 31a and the driven roller 31b constituting the feeding roller 31 is released. The nip is formed, for example, by pressing the driven roller 31b against the driving roller 31a by a lift mechanism (not shown) and coming into contact with the driving roller 31a. The nip is released by, for example, pushing up the driven roller 31b by a motor-driven lift mechanism.

  In this state, a nip between the driving roller 13a and the driven roller 13b constituting the pulling roller 13 is formed, and similarly, a nip of the pulling roller 14 is formed and driven and conveyed from the circulation refeed path 26. The sheet P in the face-down state after image formation (fixing) is taken into the bottom side of the apparatus main body 21.

  Thereafter, in the ADU reversing unit 201 viewed from the side surface side of the apparatus main body portion 21 shown in FIG. 7A, the paper P taken into the bottom surface side of the apparatus main body portion 21 is sent to the U-turn guide portion 24. At this time, the nip between the driving roller 13a and the driven roller 13b constituting the drawing roller 13 is released, and similarly, the driving of the drawing roller 14 is released and the feeding roller 31 is driven, so that the conveyance direction of the paper P Is switched from the paper transport direction Y to the paper transport direction X.

  At this time, the feed roller 31 forms a nip between the driving roller 31a and the driven roller 31b, and the motor 34 rotates to feed the paper P in the paper transport direction X substantially perpendicular to the paper transport direction Y, thereby providing a U-turn guide. It is made to convey in the part 24 (refer FIG. 7A).

  In the U-turn guide unit 24, the conveyance direction of the paper P is gradually changed from the paper conveyance direction X to the paper conveyance direction Z, and after passing through the intermediate point, the conveyance direction of the paper P is gradually changed from the paper conveyance direction Z. The transport direction is changed to X.

  Then, in the ADU reversing unit 201 viewed from the side surface side of the apparatus main body 21 shown in FIG. At this time, in the ADU reversing unit 201, the nip between the driving roller 15a and the driven roller 15b constituting the drawing roller 15 is released, and similarly, the driving of the drawing roller 15 is also released.

  At this time, the receiving roller 32 forms a nip between the driving roller 32a and the driven roller 32b, and the motor 35 rotates, so that the paper P moves from the paper transport direction Z to the paper transport direction X at the exit of the U-turn guide portion 24. Although the direction is returned, the state is reversed (face-up state).

  Thereafter, in the ADU reversing unit 201 as viewed from the top plate surface side of the apparatus main body 21 shown in FIG. 8, the paper P moves in the paper transport direction Y, that is, from the top plate surface side of the apparatus main body 21 to the refeed path 27. Discharged. At this time, in the ADU reversing unit 201, the nip of the receiving roller 32 is released, the nip of the driving roller 15a and the driven roller 15b constituting the pulling roller 15 is formed, and similarly, the nip of the pulling roller 16 is formed. The face-up paper P that is driven and turned upside down is conveyed from the ADU inversion unit 201 to the refeed path 27.

  The paper P in the face-up state after the front and back is reversed is fed again to the paper feed path 10 via the loop roller 17 shown in FIG. At this time, the face-up paper P is transported from the paper transport direction Y in the paper transport direction Z, and is transported again in the paper transport direction Y, so that the back surface of the image P is below the image forming unit 6. The paper P is set in the image forming unit 6 in the face-down state. In the image forming unit 6, an image is formed on the paper P in the face-down state. As a result, images can be formed on both sides of the paper P.

  As described above, according to the ADU reversing unit 201 as the first embodiment, when the paper P received from the paper transport direction Y is reversed and output, the U-turn guide unit 24 and the motors 33, 34, and 35 are output. A partition plate 22 is provided between the apparatus and the transport driving unit 23, and is configured to partition the inside of the apparatus main body 21.

  Due to the structure of the partition plate 22, heat generated by the motor 33 that drives the delivery roller 31, the motor 34 that drives the reception roller 32, and the motor 35 that drives the drawing rollers 15 and 16 propagates to the U-turn guide portion 24. Can be blocked. Thereby, since the temperature rise in the U-turn guide part 24 can be suppressed, the image abnormality of the paper P caused by the temperature rise can be prevented.

  Next, an example of the internal configuration of the ADU inverting unit 202 as the second embodiment will be described with reference to FIG. The ADU reversing unit 202 shown in FIG. 9 is provided with an opening 29 for air circulation in one side frame 21 a of the apparatus main body 21. The size of the opening diameter of the opening 29 and the number of the openings 29 may be arbitrarily determined depending on the diameter D of the arc portion of the U-turn guide portion 24. The diameter D is equal to the height from the bottom of the apparatus main body 21 to the top plate. For example, the opening 29 is configured by arranging a plurality of opening portions 29 a having an opening diameter d of about 10% of the diameter D of the arc portion of the U-turn guide portion 24. Of course, the opening diameter d and the number of the openings 29a are arbitrary.

  If such an opening 29 is installed in the side frame 21a of the apparatus body 21, the fresh air easily passes between the U-turn guide 24 and the partition plate 22, and the air is less likely to stagnate in that region. In addition, since the thing with the same code | symbol and the same name as a 1st Example has the same structure and the same function, the description is abbreviate | omitted.

  As described above, according to the ADU reversing unit 202 as the second embodiment, a plurality of apertures are formed in the space region surrounded by the U-turn guide 24, the partition plate 22, and the side frame 21a of the apparatus main body 21. Air can be naturally circulated through the opening 29 constituted by 29a, and the cooling effect of the space region can be enhanced. Air hardly stayed in the U-turn guide portion 24.

  In the ADU reversing unit 202, the opening 29 may be provided on each side of the apparatus main body 21 that faces each other on the side frame 21 a. If the ADU reversing unit 202 is configured in this manner, air can be naturally circulated to the space region through the mutual opening 29, and the cooling effect of the space region can be further enhanced. By improving the cooling effect in this space region, it is possible to prevent the occurrence of image abnormality.

  Next, an example of the internal configuration of the ADU inversion unit 203 as the third embodiment will be described with reference to FIG. The ADU reversing unit 203 shown in FIG. 10 includes a cooling fan 39 on the side frame 21 a of the apparatus main body 21, and is surrounded by the U-turn guide 24, the partition plate 22, and the side frame 21 a of the apparatus main body 21. Cooling air was forcibly blown into the space area. As a result, the U-turn guide portion 24 can be forcibly cooled.

  The fan 39 has one air circulation opening 39a having an opening diameter d of about 30% of the diameter D of the arc portion of the U-turn guide portion 24 described in the second embodiment of the apparatus main body 21. The fan 39 is attached to the opening 39a provided on the side frame 21a on one side.

  The other side may be the opening 29 having the plurality of apertures 29a described in the second embodiment, or may be provided with a similar fan 39. It is only necessary to obtain air circulation. As the fan 39, for example, a fan driven by a DC motor is used. In addition, since the thing with the same code | symbol and the same name as a 1st Example has the same structure and the same function, the description is abbreviate | omitted.

  As described above, according to the ADU reversing unit 203 as the third embodiment, when the cooling fan 39 is attached to the opening 39a on one side, the outside air is evacuated through the one opening 39a. By forcibly blowing into the area and forcibly discharging the warm air from the space area through the other opening 29, the warm air in the space area and the outside air can be exchanged, and the space area The inside can be forcibly cooled.

  When an intake fan 39 is attached to the opening 39a on one side and another exhaust fan is attached to the opening on the other side (not shown), the intake fan 39 is connected via the one opening 39a. Can forcibly blow air into the space area, and air can be forcibly discharged from the space area by the exhaust fan through the other opening, so that warm air in the space area and external air Can be forcibly replaced, and the cooling effect in the space region can be further enhanced. By improving the cooling effect in this space region, it is possible to prevent the occurrence of image abnormality.

  The fan 39 is not limited to the method of directly attaching to the opening 39a, the ventilation duct is attached to the opening 39a, the ventilation duct is led to the back side of the apparatus housing 101, and the fan 39 is attached to the end of the ventilation duct. You may make it attach. The outside air can be forcibly sucked into the space area through the ventilation duct and the fan 39.

  Next, with reference to FIG. 11, it is a schematic front view showing an internal configuration example of an ADU reversing unit 204 as a fourth embodiment. In the ADU reversing unit 204 shown in FIG. 11, a cooling sink portion 49 that constitutes an example of a pleat member is provided on the partition plate 22 side of the U-turn guide portion 24 having a sheet conveying structure having an arcuate cross section. The sink part 49 is composed of a plurality of fin members 49a, and increases the surface area on the inner diameter side of the U-turn guide part 24. In the figure, the case of 17 fin members 49a is taken as an example.

  The reason why the surface area is increased is that the cooling effect can be enhanced by increasing the area where fresh air touches the fin member 49a. For the fin member 49a, an aluminum plate or the like having a good heat transfer property is used. The fin members 49a are arranged so as to converge toward a center point that bisects the diameter D of the arc portion of the U-turn guide portion 24. In addition, since the thing with the same code | symbol and the same name as a 1st Example has the same structure and the same function, the description is abbreviate | omitted.

  As described above, according to the ADU reversing unit 204 as the fourth embodiment, the heat hidden in the U-turn guide portion 24 is transferred to the U-turn guide portion 24, the partition plate 22, and the apparatus main body portion 21 by the cooling sink portion 49. It becomes possible to diverge within the space region surrounded by the arc side surface portion of the arc.

  Of course, the opening 39a shown in the second embodiment and the structure of the fan 39 shown in the third embodiment may be combined. The cooling effect in the space region can be further enhanced. By improving the cooling effect in this space region, it is possible to prevent the occurrence of image abnormality.

  The shape of the opening 29 described above is not limited to a circular shape, and as shown by a two-dot chain line in FIG. 11, a part of the side frame 21a or the like is opened in a fan shape to form an opening 59. May be. The apparatus main body portion 21 holds the U-turn guide portion 24 in the spoke shape of the portion remaining after opening in the fan shape. Providing the fan-shaped opening 59 leads to weight reduction of the ADU reversing unit 204.

  According to the image forming apparatus 100 as the above-described embodiment, the first example of the ADU reversing unit 20 that reverses the paper P on which the image is formed by the image forming unit 6 and re-feeds the paper P to the image forming unit 6. Since any one of the ADU inversion units 201 to 204 according to the fourth embodiment is provided, or because these ADU inversion units 201 to 204 are combined, the ADU inversion unit 20 shown in FIG. Temperature rise can be suppressed. Accordingly, it is possible to prevent the image abnormality of the paper P caused by the temperature rise. As a result, it is possible to provide a highly reliable color image forming apparatus equipped with a duplex printing mode.

  The present invention is very suitable when applied to a monochrome printer or a color printer that forms images on both sides of a predetermined sheet based on a duplex printing mode, a copying machine, a multifunction machine, or the like.

1 Paper feeding unit 2a, 2b Feeding roller
3a, 3b, 4, 11, 12 Conveying roller 5 Registration roller 6 Image forming unit 7 Conveying belt 8 Fixing unit 9 Discharge roller 10 Paper feed path 13, 14 Pull-in roller 15, 16 Pull-out roller 17 Loop roller 20, 201-204 ADU reversing unit (sheet reversing device)
21 Device body 22 Partition plate (partition member)
23 Transport Drive Unit 24 U-Turn Guide Unit (Reverse Transport Path)
26 Circulating Refeed Path 27 Refeed Path 31 Feeding Roller (First Sheet Conveying Section)
32 Receiving roller (second sheet conveying unit)
33, 34, 35 Motor 39 Fan 49 Sink part (fold member)
49a Fin member 100 Image forming apparatus

Claims (8)

In the sheet reversing device that outputs the sheet member received from the predetermined sheet conveying direction by reversing the front and back,
The sheet member includes a reversal conveyance path provided with a sheet conveyance structure having an arc-shaped cross section in a direction substantially orthogonal to the sheet conveyance direction, and a horizontal conveyance unit that conveys the sheet member in a horizontal direction. A device main body to be reversed;
A sheet reversing apparatus comprising: a partition member provided between the sheet conveying structure of the apparatus main body and the horizontal conveying section to partition the apparatus main body. The apparatus main body has a box shape including an arc side surface portion along a sheet conveyance structure of the reverse conveyance path,
In the apparatus main body,
The sheet reversing apparatus according to claim 1, wherein a space region surrounded by the reversing conveyance path, the partition member, and a circular arc side surface portion of the apparatus main body is formed.   The sheet reversing device according to claim 2, wherein an opening for air circulation is provided in a circular arc side surface portion of the device main body. The opening is
The sheet reversing device according to claim 3, wherein the sheet reversing device is provided on each of sides facing each other at a circular arc side surface portion of the apparatus main body.   The sheet reversing device according to claim 4, further comprising a cooling fan attached to the opening on one side or the opening on both sides. A conveyance drive unit that pulls out the sheet member into the apparatus main body and sends out the sheet member after being reversed in the reverse conveyance path;
The transport driving unit is
A first sheet conveying unit that pulls the sheet member received from the sheet conveying direction into the apparatus main body and sends the sheet member in a direction substantially orthogonal to the sheet conveying direction and conveys the sheet member into the reverse conveying path;
A second sheet conveying unit that pulls out the sheet member from the reversing conveyance path and sends out the sheet member after reversing the front and back from the inside of the apparatus main body and conveys the sheet member in a predetermined sheet conveying direction;
The sheet reversing apparatus according to claim 1, further comprising a driving unit that drives the first and second sheet conveying units.   The sheet reversing device according to claim 1, wherein a cooling pleat member is provided on a side of the partition member of the reversing conveyance path having the sheet conveying structure having an arcuate cross section. An image forming unit that forms an image on a predetermined sheet member;
A sheet reversing unit for reversing the sheet member imaged by the image forming unit,
The sheet reversing part is
An image forming apparatus comprising the sheet inverting device according to claim 1, or a combination of these sheet inverting devices.

Images