JP2008185646A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that can prevent a sheet material from curling by an inexpensive configuration. <P>SOLUTION: A sheet material P dried by the heat of a fixing device 38 is fed in a direction of an arrow (A) tilted in the opposite side with respect to a discharge roll 40, turned along the guide face 50A of a guide member 50 and fed in a horizontal direction (an arrow B direction) by rotary driving force of a water absorbing conveyance roll 56. A water vapor retention space 54 formed by a paper discharge passage 48 retains water vapor vaporized from the sheet material P by the heat of a heating roll 38A and is absorbed by the sheet material P fed in the horizontal direction by the guide member 50. By making the sheet material P dried by the fixing device 38 absorb the water vapor, the sheet material P is prevented from curling. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus provided with a fixing device.

  In the image forming apparatus, the toner image on the photosensitive drum provided in the image forming unit is transferred to a sheet material (recording medium), and then heat-pressed to the sheet material by a fixing device, and is discharged to a discharge tray by a discharge roll. The

  Here, when the sheet material is heat-pressed by the fixing device, moisture contained in the sheet material is released as water vapor. As a result, the sheet material is deprived of moisture and the sheet material is curled.

Therefore, two plate-like guide plates are provided on the front side and the back side of the sheet material along the conveyance path between the fixing unit and the discharge roll, and water vapor released by the fixing unit is provided between the two guide plates. An image forming apparatus has been proposed in which water vapor is absorbed into a sheet material from which moisture has been removed to prevent curling. (Patent Document 1)
JP 2001-26352 A

  However, according to this image forming apparatus, a plate-shaped guide plate has to be provided along the conveyance path between the fixing device and the discharge roll, so that the configuration is expensive.

  In view of the above facts, it is an object of the present invention to provide an image forming apparatus capable of preventing curling of a sheet material with an inexpensive configuration.

  An image forming apparatus according to a first aspect of the present invention fixes an image forming unit that forms a toner image on a sheet material and the toner image received from the image forming unit to the sheet material by thermocompression bonding. A fixing device that sends the sheet material in a first direction, and a guide member that folds the sheet material sent in the first direction by the fixing device in a second direction and passes above the fixing device. It is characterized by having.

  According to the above configuration, a toner image is formed on the sheet material in the image forming unit, and the fixing device fixes the toner image to the sheet material by heat-pressing and feeding the sheet material in the first direction.

  In this manner, the fixing device heat-presses the toner image, whereby moisture contained in the sheet material is discharged as water vapor to the upper side of the fixing device, and the sheet material is dried because moisture is taken away.

  Further, the dried sheet material fed in the first direction is folded back in the second direction by the guide member and passes above the fixing device.

  In this way, by allowing the sheet material to pass over the fixing device, the water vapor rising from the fixing device is blocked by the sheet material, and a water vapor retention space in which the water vapor stays is formed.

  That is, when the sheet material passes above the fixing device, the water vapor remaining in the water vapor retention space can be absorbed, thereby preventing the sheet material from curling.

  Thus, curling of the sheet material can be prevented with an inexpensive configuration.

  An image forming apparatus according to a second aspect of the present invention is the image forming apparatus according to the first aspect, wherein a water-absorbing conveyance roll having a surface formed of a water-absorbing member is disposed in a paper discharge path from the fixing device to the discharge port of the sheet material. It is provided.

  According to the above configuration, since the water absorption transport roll whose surface is formed of the water absorption member is provided in the paper discharge path from the fixing device to the sheet material discharge port, the amount of water vapor in the water vapor retention space is large. In this case, the water absorption transport roll absorbs excess water vapor. For this reason, it is possible to prevent water vapor from condensing.

  An image forming apparatus according to a third aspect of the present invention is the image forming apparatus according to the first or second aspect, wherein the second direction is a horizontal direction.

  According to the above configuration, the second direction in which the sheet material is folded by the guide member is the horizontal direction. That is, since the sheet material absorbs the rising water vapor while being conveyed in the horizontal direction, the sheet material can absorb the water vapor more efficiently than the case of absorbing the rising water vapor while being conveyed while being inclined.

  An image forming apparatus according to a fourth aspect of the present invention is the image forming apparatus according to any one of the first to third aspects, wherein the guide member is provided with a gap through which water vapor and heat pass.

  According to the above configuration, the guide member is provided with a gap through which water vapor and heat pass. For this reason, since water vapor | steam passes through this clearance gap and it rises, it can prevent that water vapor | steam condenses on a guide member.

  Furthermore, since condensation can be prevented, paper jam, sheet material contamination, and sheet material deformation caused by water droplets adhering to the sheet material can be prevented.

  According to the image forming apparatus of the present invention, curling of the sheet material can be prevented with an inexpensive configuration.

  An image forming apparatus 10 according to an embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 5, the image forming apparatus 10 includes a housing 12 as a casing, and a developing device 24Y that forms a yellow toner image in the housing 12, a developing device 24M that forms a magenta toner image, and cyan. A developing device 24C for forming the toner image and a developing device 24K for forming the black toner image are arranged in the vertical direction in order from the top. In addition, when it is necessary to distinguish YMCK, it demonstrates by attaching | subjecting any one of Y, M, C, and K after a code | symbol, and when it is not necessary to distinguish YMCK, YMCK is abbreviate | omitted.

  On the other hand, the photosensitive member cartridge 18 includes a drum-shaped photosensitive member 22 and a charging roll 26 that charges the surface of the photosensitive member 22. An optical scanning device 14 corresponding to each color for exposing the surface of the photoconductor 22 to form an electrostatic latent image is disposed adjacent to the photoconductor cartridge 18.

  The developing rolls 20 provided in the developing units 24Y, 24M, 24C, and 24K respectively transfer the electrostatic latent image on the photosensitive member 22 with yellow (Y), magenta (M), cyan (C), and black (K) toners. develop.

  Further, a transfer roll 30 for transferring the toner image on the photosensitive member 22 to a sheet material P as a recording medium is disposed so as to face the photosensitive member 22 and constitutes an image forming unit 31.

  On the other hand, a sheet feeding cassette 16 that accommodates the sheet material P is provided in a lower portion in the housing 12. The paper feed cassette 16 is provided with a feed roll 32 that feeds the sheet material P at a predetermined timing. A registration path 28 is provided between the feed roll 32 and the developing unit 24K. A roll 34 is provided, and an optical sheet material passage sensor 36 is disposed downstream of the registration roll 34 in the sheet material P conveyance direction.

  The sheet material passage sensor 36 detects the leading edge of the sheet material P, and the electrostatic latent image writing timing of each optical scanning device 14 is controlled based on the detection timing. Further, a fixing path 38 for fixing the toner image to the sheet material P by heat-pressing the toner image is provided in the transport path 28 located on the downstream side in the sheet material transport direction of the developing device 24Y. A heating roll 38A and a pressure roll 38B with a built-in heater are provided.

  The sheet material P is discharged from the fixing device 38 to the discharge furnace example 42 on the upper surface of the housing 12 by the discharge roll 40 disposed at the discharge port 39, and the sheet along the discharge path 48. Details of the guide member 50 for guiding the material P will be described later.

  In the image forming apparatus 10 configured as described above, an image is formed as follows.

  First, the charging roll 26 to which a voltage is applied uniformly charges the surface of the photoconductor 22 at a predetermined potential.

  Subsequently, exposure is performed by the optical scanning device 14 so that an image portion on the charged photosensitive member 22 has a predetermined exposure portion potential, and an electrostatic latent image is formed on the photosensitive member 22.

  That is, a latent image corresponding to an image is formed on the photosensitive member 22 by turning on and off the optical scanning device 14 based on image data supplied from a control device (not shown).

  Further, a developing bias set in advance for each color is applied to the developing roll 20 of the developing device 24, and the latent image is developed with toner when passing through the position of the developing roll 20, and is visualized as a toner image.

  Therefore, the sheet material P passes through the image forming unit 31 between the photoreceptor 22 and the transfer roll 30, and the toner image is transferred to the sheet material P. The sheet material P to which the toner image has been transferred is guided by the guide member 44 and the guide member 46 and sent to the fixing device 38. Then, the sheet material P passes between the heating roll 38 </ b> A and the pressure roll 38 </ b> B provided in the fixing device 38, so that the toner image is fixed on the sheet material P.

  The sheet material P sent out from the fixing device 38 is guided by a guide member 50 which will be described later, and is discharged to a discharge tray 42 formed on the upper portion of the housing 12 by a discharge roll 40.

  Next, the sheet discharge path 48 for the sheet material P sent out by the fixing device 38, the guide member 50 for guiding the sheet material P along the sheet discharge path 48, and the like will be described in detail.

  As shown in FIG. 1, the fixing device 38 for fixing the toner image to the sheet material P includes the heating roll 38A having a built-in heater and the pressure roll 38B in pressure contact with the heating roll 38A, as described above. Yes.

  When the sheet material P passes through the fixing device 38, the moisture contained in the sheet material P is released upward as water vapor by the heat of the heating roll 38A, and the sheet material P is deprived of moisture and dried.

  Further, by inclining the fixing device 38, the heating roll 38 </ b> A is disposed obliquely above the pressure roll 38 </ b> B, and the sheet material P is the first inclined to the opposite side with respect to the discharge roll 40. It is sent out in the diagonally upward direction (arrow A direction).

  Further, the sheet material P sent out from the fixing device 38 in the direction of arrow A is guided in the horizontal direction (arrow) by a guide member 50 (resin in this embodiment) having a curved guide surface 50A. B direction), passes over the fixing device 38 and is conveyed along the upper surface of the sheet material conveyance chute 52 (made of resin in this embodiment) having a rectangular cross section, and is discharged to the discharge tray 42 by the discharge roll 40. It is configured to be discharged.

  Thus, by passing the sheet material P over the fixing device 38, the water vapor rising from the fixing device 38 is blocked by the sheet material P, and a water vapor retention space 54 in which the water vapor stays is formed.

  Further, as shown in FIG. 3, the guide member 50 has a comb shape and is provided with a gap 50 </ b> B through which water vapor or heat passes.

  As shown in FIG. 1, at a position facing the guide member 50, a water absorption conveyance roll 56 whose surface is formed of a water absorption member (for example, a sponge material) is rotationally driven to discharge the sheet material P to the paper discharge path 48. It is designed to be transported along.

  Further, the top plate 12A of the housing 12 disposed above the fixing device 38 is provided with a plurality of rectangular openings 60 through which heat and water vapor are discharged.

  Further, a door 62 that can be opened and closed is provided on the side surface of the housing 12 for maintenance of the image forming apparatus 10. A guide member 50 is attached to the door 62. As shown in FIG. 2, the door 62 opens an upper portion of the housing 12 with a hinge (not shown) provided below the door 62 as a rotation center. It has a configuration. With this configuration, when the sheet material P is jammed in the vicinity of the fixing device 38, the door 62 is opened so that the jammed sheet material P can be removed.

  Further, as shown in FIG. 4, the discharge roll 40 that discharges the sheet material P to the discharge tray 42 is a skewer roll, and water vapor and heat are released from the gap between the adjacent discharge rolls 40. ing.

  With the above configuration, as shown in FIG. 1, the moisture contained in the sheet material P is released as water vapor by the fixing device 38 above the fixing device 38 (in the direction of arrow C), and the sheet material P is deprived of moisture. And dry.

  Further, the dried sheet material P is fed in the direction of arrow A inclined to the opposite side with respect to the discharge roll 40, and is rotated along the guide surface 50 </ b> A of the guide member 50, while the rotational driving force of the water absorbing and conveying roll 56. Then, it is sent in the horizontal direction (arrow B direction).

  Here, in the water vapor staying space 54 formed by the paper discharge path 48, the water vapor evaporated from the sheet material P due to the heat of the heating roll 38 </ b> A stays, and the sheet material sent out in the horizontal direction by the guide member 50. P absorbs moisture.

  In this way, the sheet material P dried by the fixing device 38 absorbs water vapor to prevent the sheet material P from curling. Further, the sheet material P can be cooled.

  Further, the sheet material P is folded back from the guide member 50 in the horizontal direction, and the sheet material P absorbs the rising water vapor while being conveyed in the horizontal direction. Then, water vapor can be absorbed efficiently.

  Further, since the water discharge / conveying roll 56 whose surface is formed of a water absorbing member is provided in the paper discharge path 48, when the amount of water vapor in the water vapor retention space 54 is large, the water absorbing / conveying roll 56 absorbs excess water vapor. Therefore, it is possible to prevent water vapor from condensing.

  The guide member 50 has a comb shape and is provided with a gap 50B (see FIG. 3) through which water vapor and heat pass. For this reason, since water vapor | steam passes through this clearance gap 50B and rises, it can prevent adhering to the guide member 50 and dew condensation.

  Furthermore, since dew condensation is prevented, it is possible to prevent paper jam, sheet material contamination, and sheet material deformation caused by water droplets adhering to the sheet material P.

  The top plate 12A of the housing 12 disposed above the fixing device 38 is provided with a plurality of rectangular openings 60 through which heat and water vapor are discharged. For this reason, the excess water vapor | steam which rose from between the sheet | seat material P and the subsequent sheet | seat material P conveyed can be discharged | emitted through the opening part 60. Thus, since excess water vapor can be discharged, there is no need to provide an opening in the vicinity of the fixing device 38, and the driving sound of the fixing device 38 and the conveying sound of the sheet material P are prevented from leaking outside. Can do.

  Further, as shown in FIG. 4, since the discharge roll 40 is a skewer roll, surplus water vapor and heat can be released from the gap between adjacent discharge rolls 40.

  In addition, a corrugation roller (not shown) forcibly generates a wave in a direction orthogonal to the sheet material conveyance direction, takes a curl from the sheet material P, and smoothly discharges the sheet material P to the discharge tray 42. However, when the wave is forcibly generated in the curled sheet material P, noise generated by forcibly folding the sheet material P is generated. However, as described above, the sheet material P absorbs water vapor and prevents curling, so that noise caused by the corrugation roller can be suppressed.

  Further, the image forming apparatus 10 is provided with a curl correction device (not shown) that removes curl generated in the sheet material P, and noise generated by forcibly folding the sheet material P when forcing the curl. Will occur. However, as described above, since the sheet material P absorbs water vapor and prevents curling, noise caused by the curl correction device can also be suppressed.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It is clear to the contractor. For example, in the above-described embodiment, the fixing device 38 is inclined to adjust the feeding direction of the sheet material P from the fixing device 38. However, the present invention is not limited to this, and the heating roll 38A provided in the fixing device 38 and the pressurizing force are provided. The feeding direction of the sheet material P from the fixing device 38 may be adjusted by adjusting the positional relationship of the roll 38B.

  Moreover, in the said embodiment, although the material of the guide member 50 and the sheet material conveyance chute 52 was resin, the material (for example, hard sponge) which has water absorption is employ | adopted for the id member 50 and the sheet material conveyance chute 52, Excess water vapor existing in the water vapor retention space 54 may be absorbed.

FIG. 2 is a cross-sectional view illustrating an image forming apparatus according to an exemplary embodiment of the present invention and illustrating a fixing device 38, a paper discharge path 48, and the like. FIG. 3 is a cross-sectional view of the image forming apparatus according to the embodiment of the present invention, when the door 62 disposed on the side of the fixing device 38 is opened. FIG. 3 is a perspective view showing a guide member 50 of the image forming apparatus according to the embodiment of the invention. FIG. 3 is a perspective view showing the vicinity of a discharge roll 40 of the image forming apparatus according to the embodiment of the present invention. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 31 Image forming part 38 Fixing device 39 Discharge port 48 Discharge path 50 Guide member 50B Gap 54 Water vapor retention space 56 Water absorption conveyance roll

Claims (4)

An image forming unit for forming a toner image on a sheet material;
Fixing the toner image received from the image forming unit to the sheet material by thermocompression bonding, and sending out the sheet material in a first direction;
A guide member that folds the sheet material fed in the first direction by the fixing device in a second direction and passes above the fixing device;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein a water absorption conveyance roll having a surface formed of a water absorption member is provided in a paper discharge path from the fixing device to the discharge port of the sheet material.   The image forming apparatus according to claim 1, wherein the second direction is a horizontal direction.   The image forming apparatus according to claim 1, wherein the guide member is provided with a gap through which water vapor and heat pass.

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