JP2015107847A - Paper transportation device and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability of an endless belt, in a paper transportation device and an image formation device that uses the paper transportation device, which transports paper by sucking it on the endless belt by air suction.SOLUTION: A paper transportation device includes an endless belt made from fabric, a rotational member on which the endless belt is wound and circulated by rotation, and a wind tunnel member which is arranged inside the endless belt to contact to the inside surface of the endless belt, and in which, an air sucking opening is formed at a portion facing an outward path side of the endless belt, for sucking air, so that the paper to be transported is sucked on an outside surface of the endless belt outward path.

Description

  The present invention relates to a sheet conveying device and an image forming apparatus.

  2. Description of the Related Art Conventionally, there is known an apparatus that adsorbs and conveys a sheet on an endless belt by air suction.

  Here, Patent Document 1 discloses an endless belt made of a woven fabric in which fibers are woven in a mesh shape and using the woven fabric so that the weaving direction is oblique to the belt running direction.

  Patent Document 2 discloses an endless belt made of a woven fabric as in Patent Document 1, the weaving direction being slanted with respect to the belt traveling direction, and an endless belt having a surface treated on one surface thereof. A belt is disclosed.

  Further, Patent Document 3 discloses an endless belt formed of a polyurethane nonwoven fabric.

JP 2011-116543 A JP 2011-121684 A JP 2010-168203 A

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet conveying apparatus that adsorbs and conveys a sheet onto an endless belt by suction of air, and an image forming apparatus using the sheet conveying apparatus.

Claim 1
An endless belt made of knitted fabric,
A rotating member around which the endless belt is wound and rotated to rotate the endless belt;
An air suction port is formed in a portion of the endless belt that is in contact with the inner surface of the endless belt and faces the forward path side of the endless belt, and sucks air so that the paper to be conveyed is transported to the outer surface of the endless belt forward path side. A paper conveying device comprising a wind tunnel member to be adsorbed.

  According to a second aspect of the present invention, the endless belt includes at least a first type of fibers having a relatively high coefficient of friction with the paper and exposed relatively abundantly on an outer surface in contact with the paper, and the wind tunnel member. A friction coefficient between them is relatively low, and is composed of a knitted fabric using a plurality of types of fibers including a second type of fibers exposed relatively abundantly on the inner surface in contact with the wind tunnel member. The sheet conveying device according to claim 1.

  According to a third aspect of the present invention, in the paper conveying apparatus according to the second aspect, the endless belt is formed of a knitted fabric knitted by plating knitting.

  The paper conveying apparatus according to any one of claims 1 to 3, wherein the first type of fiber is a urethane fiber and the second type of fiber is a nylon fiber. It is.

Claim 5
A toner image forming unit that forms a toner image on paper;
A fixing unit for fixing the toner image on the paper on which the toner image is formed on the paper;
A first conveying unit that conveys a sheet on which a toner image is formed in the toner image forming unit to the fixing unit;
A second transport unit that further transports the paper on which the toner image is fixed in the fixing unit,
At least one of the first transport unit and the second transport unit transports a sheet using the sheet transport apparatus according to any one of claims 1 to 4. The image forming apparatus.

  According to the paper conveying device of the first aspect and the image forming device of the fifth aspect, the durability is superior to the endless belt made of a woven fabric.

  According to the paper transport device of the second aspect, the high performance is maintained for a long time as compared with the endless belt subjected to the surface treatment.

  According to the paper conveying device of the third aspect, it is easy to form a high-performance endless belt as compared with other knitting methods.

  According to the paper conveying apparatus of the fourth aspect, an endless belt having higher performance and higher durability than the combination of other types of fibers can be configured.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. FIG. 6 is a schematic configuration diagram illustrating one of six image forming units. FIG. 4 is a schematic side view of a first paper transport unit, a fixing unit, and a second paper transport unit. FIG. 6 is a perspective view showing an upper surface side of the first paper transport unit. FIG. 5 is a perspective view showing the back side of the first paper transport unit turned upside down. FIG. 6 is a perspective view showing an upper surface side of a second paper transport unit. FIG. 6 is a perspective view illustrating a lower surface side of a second paper transport unit. It is an expansion schematic diagram of an endless belt.

  Embodiments of the present invention will be described below.

  FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. In this image forming apparatus, a sheet conveying apparatus according to an embodiment of the present invention is incorporated.

  The image forming apparatus 10 shown in FIG. 1 includes a first housing 10A disposed on the left side of FIG. 1 and a second housing 10B disposed on the left side thereof.

  An image signal processing unit 13 is provided in the upper part of the second housing 10B. The image signal processing unit 13 receives image data transmitted from an external device (not shown) such as a computer, and performs image processing on the received image data. The image forming apparatus 10 is an apparatus that forms an image on a sheet based on image data received by the image signal processing unit 13 and subjected to image processing. Toner cartridges 14V, 14W, 14Y, 14M, 14C, and 14K are arranged in the horizontal direction in the upper part of first housing 10A. These toner cartridges 14V, 14W, 14Y, 14M, 14C, and 14K have a first special job (V), a second special color (W), yellow (Y), magenta (M), and cyan (C), respectively. , Black (K) toners are accommodated. The first special job (V) and the second special color (W) are colors (including transparency) that are appropriately selected according to the use of the user of the image forming apparatus 10. These toner cartridges 14V, 14W, 14Y, 14M, 14C, and 14K are all detachable, and a new toner cartridge 14V is used when the toner contained therein is used and empty as will be described later. , 14W, 14Y, 14M, 14C, 14K.

  In the following description, when it is not necessary to distinguish the constituent elements for each color, the subscripts V, W, Y, M, C, and K representing the colors are omitted, for example, as in the toner cartridge 14. In the title.

  Under the toner cartridge 14, six image forming units 16 are arranged in a horizontal direction. These six image forming units 16 are units for forming toner images composed of toners of the colors V, W, Y, M, C, and K, respectively.

  FIG. 2 is a schematic configuration diagram showing one of the six image forming units. In FIG. 2, each component is shown with a reference numeral in which a subscript representing a color is omitted.

  Each image forming unit 16 includes an optical scanning device 40. The optical scanning device 40 receives input of image data subjected to image processing in the image signal processing unit 13 described above, and generates a light beam L modulated according to the input image data. The optical scanning device 40 scans the image carrier 18 with the generated light beam L.

  The image carrier 18 rotates in the direction of arrow A, and while rotating, an electrostatic latent image is formed on the surface thereof, and the electrostatic latent image is developed with toner to hold the toner image as described below. .

  Around the image carrier 18, a scorotron charger 20, a developing device 22, a cleaning blade 24, and a static elimination lamp 26 are provided. A primary transfer roll 36 is disposed at a position facing the image carrier 18 with an intermediate transfer belt 34 described later interposed therebetween.

  The scorotron charger 20 is a corona charging type charger, and charges the surface of the image carrier 18 to a uniform potential in a non-contact manner.

  The above-described optical scanning device 40 scans the uniformly charged region of the image carrier 18 with the light beam L modulated in accordance with the image data. An electrostatic latent image representing an image corresponding to the image data is formed.

  The developing device 22 includes a developer storage chamber 22A and a developing roll 22B. The developer storage chamber 22 </ b> A is a chamber for storing the developer G containing toner supplied from the corresponding toner cartridge 14. Further, the developing roll 22B rotates in the direction of arrow B, and carries the developer G accommodated in the developer accommodating chamber 22A to the developing area S facing the image carrier 18. The toner in the developer G carried in the development area S by the developing roll 22B adheres to the image holding body 18 in accordance with the potential of each point of the electrostatic latent image on the image holding body 18, thereby the image holding body. A toner image is formed on 18.

  The toner image formed on the image carrier 18 is transferred onto the intermediate transfer belt 34 running in the direction of arrow C by the action of the primary transfer roll 36. The toner remaining on the surface of the image carrier 18 after the transfer of the toner image is removed by the cleaning blade 24. Further, the image carrier 18 is erased from the remaining electrostatic latent image by being irradiated with light from a static elimination lamp 26 that performs static elimination by light irradiation, and is prepared for the formation of the next electrostatic latent image.

  Returning to FIG. 1, the description will be continued.

  A transfer unit 32 including an intermediate transfer belt 34 and a primary transfer roll 36 is provided below the six image-type units 16 arranged side by side.

  The intermediate transfer belt 34 is an annular belt and is wound around a drive roll 38, a tension applying roll 41, a backing roll 42, and a plurality of winding rolls 44. The drive roll 38 is a roll that rotates the intermediate transfer belt 34 by rotation. The tension applying roll 41 is a roll that applies tension to the intermediate transfer belt 34. Further, the backing roll 42 is placed at a position where the intermediate transfer belt 34 is sandwiched between the backing transfer roll 62 and the inner side of the intermediate transfer belt 34 to press the secondary transfer roll 62 against the intermediate transfer belt 34. It is a roll that supports from.

  The intermediate transfer belt 34 rotates around the path including the path facing the image carrier 18 of each of the six image forming units 16 by the rotation of the drive roll 38. During the circular movement, each toner image formed on the image carrier 18 of each image forming unit 16 is transferred so as to be sequentially stacked on the intermediate transfer belt 34 by the action of each primary transfer roll 36. Is done. The toner image transferred onto the intermediate transfer belt 34 is conveyed by the intermediate transfer belt 34 to the secondary transfer position T where the secondary transfer roll 62 is disposed. As will be described later, the sheet P is conveyed to the secondary transfer position T at a timing that matches the timing at which the toner image is conveyed to the secondary transfer position T, and the toner image on the intermediate transfer belt 34 is transferred to the sheet. Transferred onto P.

  In the lower part of the first housing 10A, two paper storage units 48 in which the paper P is stored are provided horizontally. Each paper storage unit 48 can be pulled out from the first housing 10A for replenishment of paper P and the like. At the upper right side of FIG. 1 of each paper storage unit 48, a feed roll 52 is provided for sending the paper P stored in the paper storage unit 48 toward the transport path 60.

  In each sheet storage unit 48, a bottom plate 50 on which the sheet P is placed is provided. The bottom plate 50 is lowered when the paper storage unit 48 is pulled out from the first housing 10A, and a space in which the paper P is replenished is formed. When the paper storage unit 48 is mounted in the first housing 10 </ b> A, the bottom plate 50 rises to a height at which the uppermost paper P hits the feed roll 52. On the downstream side in the paper conveyance direction of the delivery roll 52 (hereinafter, the downstream side in the paper conveyance direction is simply referred to as “downstream side”. Similarly, the upstream side in the paper conveyance direction is simply referred to as “upstream side”). A separation roll 56 is provided. A transport path 60 on the downstream side of the separation roll 56 is provided between the sheet storage unit 48 and the transfer unit 32, and a plurality of transport rolls 54 and a timing adjustment roll 64 are provided on the transport path 60. ing.

  The separation roll 56 is a roll that reliably separates the sheet P into one sheet and sends out only one sheet when the plurality of sheets P are fed out while being overlapped by the feeding roll 52. The paper P sent out from the separation roll 56 is transported by the transport roll 54 and folded back in the direction of the arrow D by the first folding section 60A, and then folded back in the direction of the arrow E by the second folding section 60B. Up to 64. The timing adjustment roll 64 adjusts the feed timing so that the paper P reaches the secondary transfer position at the same timing as the timing at which the toner image on the intermediate transfer belt 34 reaches the secondary transfer position T. It is a roll which sends out P.

  Here, a spare path 66 extending from the side surface is provided in the first housing 10A. The preliminary path 66 is used for joining the sheet P sent to the first casing 10A from the sheet storage device (not shown) arranged adjacent to the first casing 10A on the left side of FIG. This is the transport route.

  The sheet P fed from the timing adjustment roll 64 is sandwiched between the intermediate transfer belt 34 and the secondary transfer roll 62 at the secondary transfer position T, and the toner image on the intermediate transfer belt 34 is obtained by the action of the secondary transfer roll 62. Is transferred onto the paper P. The toner remaining on the intermediate transfer belt 34 after the transfer to the paper P is removed from the intermediate transfer belt 34 by the belt cleaner 46.

  A plurality of conveyor belts 70 are provided on the downstream side of the secondary transfer position T in the first housing 10A. Each of the conveyor belts 70 is formed in an annular shape, and is wound around a pair of winding rolls 72. These conveyor belts 70 rotate in the direction in which the upper surface side moves downstream as the winding roll 72 rotates.

  The paper P that has received the transfer of the toner image at the secondary transfer position T is placed on the transport belt 70 and transported downstream, sent out from the first housing 10A, and delivered to the second housing 10B. .

  In the second housing 10B, a first paper transport unit 80, a fixing unit 82, and a second paper transport unit 108 are arranged from the upstream side toward the downstream side. The paper P delivered to the second housing 10 </ b> B is transported further downstream by the first paper transport unit 80 and passes through the fixing unit 82.

  FIG. 3 is a schematic side view of the first paper transport unit, the fixing unit, and the second paper transport unit.

  First, the fixing unit will be described. The first paper transport unit and the second paper transport unit will be described later with reference to FIG. 3 and the subsequent drawings.

  The fixing unit 82 includes a fixing belt 84 and a pressure roll 88. The pressure roll 88 is disposed at a position in contact with the fixing belt 84 from below. The conveyed paper P passes through the fixing position N sandwiched between the fixing belt 84 and the pressure roll 88.

  The fixing belt 84 is formed in an annular shape and is wound around a driving roll 89 and two driven rolls 90 and 91. The drive roll 89 is disposed at a position facing the pressure roll 88 with the fixing belt 84 interposed therebetween. A pressing roll 92 is pressed against the outer surface of the fixing belt 84. The drive roll 89 rotates in the direction of arrow F and moves the fixing belt 84 in the same direction. The driving roll 89 and the driven roll 90 each have a built-in heating unit such as a halogen heater, whereby the fixing belt 84 is heated.

  The paper P transported by the first paper transport unit 80 is sandwiched between the fixing belt 84 and the pressure roll 88 at the fixing position N and is heated and pressurized, and the toner on the paper P is heated and pressurized. The image is fixed on the paper P. As a result, an image composed of a fixed toner image is formed on the paper P.

  The sheet P on which the toner image has been fixed by the fixing unit 82 is conveyed further downstream by the second sheet conveying unit 108. Although details will be described later, each of the first paper transport unit 80 and the second paper transport unit 108 corresponds to an example of the paper transport device of the present invention.

  Returning to FIG. 1, the description will be continued.

  A cooling unit 110 is disposed further downstream of the second paper transport unit 108 in the second housing 10B. The cooling unit 110 serves to cool the paper P heated by the fixing unit 82 while the paper P after fixing passes through the cooling unit 110.

  The cooling unit 110 includes a heat absorption device 112 and a pressing device 114. The heat absorbing device 112 is a device that serves to absorb the heat of the paper P. The pressing device 114 is a device that presses the paper P against the heat absorbing device 112.

  The endothermic device 112 includes an endothermic belt 116. The endothermic belt 116 is formed in an annular shape, is a belt that is wound around the drive roll 120 and a plurality of winding rolls 118 and moves around by the rotation of the drive roll 120. A heat sink 122 is provided inside the endothermic belt 116. The heat absorbing belt 116 absorbs heat from the paper P and transfers it to the heat sink 122, and the heat sink 122 releases the heat into the air. A fan (not shown) is provided on the back side of the second housing 10B (the back side of the sheet of FIG. 1). The fan creates a flow of air through the heat sink 122 by its rotation, transfers heat from the heat sink 122 to the air, and discharges the heated air to the outside of the second housing 10B.

  The pressing device 114 includes an annular pressing belt 130 wound around a plurality of winding rolls 132. The pressing belt 130 rotates while pressing the paper P against the heat absorbing belt 116, and in cooperation with the heat absorbing belt 116, conveys the paper P downstream.

  On the further downstream side of the cooling unit 110, a correction device 140 for correcting the curvature (curl) of the paper P passing therethrough is provided, and on the further downstream side, a defect detection device 180 is provided. The defect detection device 180 illuminates the paper P passing therethrough and detects the image defect or image position defect of the image formed on the paper P by detecting the reflected light with a CCD image sensor. It is.

  A paper discharge roll 198 is provided in the vicinity of the paper discharge port of the second housing 10 </ b> B on the downstream side of the defect detection device 180. The paper discharge roll 198 is a roll that discharges the paper P onto a paper discharge tray 196 attached to the outside of the wall surface of the second housing 10B.

  In the mode in which images are formed on both sides of one sheet, the sheet P on which the image is formed only on one side proceeds to the reverse path 202 before reaching the sheet discharge roll 198. The inversion path 202 has an inversion path 202A. The sheet P conveyed on the reverse path 202 in the direction of arrow H proceeds on the reverse path 202A in the direction of arrow I, then reverses its traveling direction, proceeds in the direction of arrow J, and joins the transport path 60. Thus, when the paper P is taken out from the paper storage unit 48, the front and back of the paper P are in an inverted posture. In the same way as described above, an image is formed on the back side of the paper P with the front and back sides reversed. In this way, the paper P on which images are formed on both the front and back sides is discharged onto the paper discharge tray 196.

  This is the end of the description of the overall configuration of the image forming apparatus 10. Next, the first paper transport unit 80 and the second paper transport unit 108 disposed before and after the fixing unit 82 will be described.

  FIG. 4 is a perspective view showing the upper surface side of the first paper transport unit.

  FIG. 5 is a perspective view showing the back side of the first paper transport unit upside down.

  Here, the first paper transport unit will be described with reference to FIGS. 4 and 5 and FIG. 3 described above.

  The first paper transport unit 80 includes a drive roll 302, a driven roll 304, four endless belts 306, and a wind tunnel member 308. The four endless belts 306 are wound around the drive roll 302 and the driven roll 304 in parallel with each other. The first paper transport unit 80 includes a motor 310, a gear 312 fixed to the shaft of the motor 310, a gear 314 fixed to the drive roll, and a gear 313 that connects the gears 312 and 314. (See FIG. 5). When the motor 310 rotates, the rotational driving force is transmitted to the driving roll 302 via the gears 312 to 314 to rotate the driving roll 302, and thereby the endless belt 306 moves around. This circumferential movement direction is a direction in which the upper surface of the endless belt 306 coincides with the conveyance direction of the paper P (the arrow X direction shown in FIG. 4). The endless belt 306, which will be described in detail later, is a belt knitted in a net shape, and an infinite number of holes penetrating the front and back are formed. The endless belt 306 is formed in an annular shape by heat sealing.

  The wind tunnel member 308 is disposed inside the endless belt 306, and the inside thereof is formed into a cavity. A number of holes (not shown) penetrating into and out of the cavity of the wind tunnel member 308 are formed in a portion of the upper surface of the wind tunnel member 308 covered with the endless belt 306, and one end of the wind member 308 is further formed. Is formed with an opening 308A connected to the internal cavity. An air suction port (not shown) of a fan 326 (see FIG. 4) attached to the second housing 10B (see FIG. 1) is connected to the opening 308A, and when the fan 326 rotates. Air is drawn through countless holes in endless belt 306 and numerous holes in the top surface of wind tunnel member 308.

  Therefore, the first paper transport unit 80 attracts the paper P to the upper surface of the endless belt 306 when the paper P is transported in the arrow X direction shown in FIG. Then, the sheet P is conveyed downstream while the sheet P is adsorbed.

  As shown in FIG. 5, the first paper transport device 80 is further provided with a regulating member 324, a cleaning roll 322, a plate-shaped guide member 318, and a static elimination brush 320.

  The regulating member 324 is a member that is fixed to the wind tunnel member 308 and protrudes from the lower surface of the wind tunnel member 308, is in contact with the end surface of the endless belt 306, and regulates the travel position of the endless belt 306.

  The cleaning roll 322 is a roll that contacts the outer surface of the endless belt 306 and removes paper dust and the like attached to the outer peripheral surface thereof.

  Further, the guide member 318 is a member that guides the paper P transported by the first paper transport unit 80 to the fixing position N of the fixing unit 82.

  Further, the static elimination brush 320 is provided at the tip of the guide member 318 and plays a role of neutralizing the paper P in contact with the paper P passing therethrough.

  The detailed description of the endless belt 306 will be described later, and next, the structure of the second paper transport unit 108 disposed on the downstream side (see FIG. 3) of the fixing unit 82 will be described.

  FIG. 6 is a perspective view showing the upper surface side of the second paper transport unit.

  FIG. 7 is a perspective view showing the lower surface side of the second paper transport unit.

  Here, the second paper transport unit will be described with reference to FIGS. 6 and 7 and FIG. 3 described above.

  The second paper transport unit 108 includes a driving roll 330, a driven roll 332, and two endless belts 334 wound around the driving roll 330 and the driven roll 332. Furthermore, another driven roll 336 is provided between the drive roll 330 and the driven roll 332. The driven roll 336 has a function of lifting the upper surface of the endless belt 334, thereby forming an inclined entry region 334 </ b> C in the endless belt 334. By forming the entry area 334C, the paper P that has passed through the fixing unit 82 and is conveyed in the direction of the arrow X is smoothly transferred onto the endless belt 334.

  In addition, between the two endless belts 334, a driven roll 336 that lifts the upper surface of the two endless belts 334, a drive roll 330, and another driven roll 396 (see FIG. 3) are wound. Another endless belt 338 is provided which is hung across. A sensor 398 for detecting the presence or absence of the paper P is provided between the entry regions 334C of the two wide endless belts 334.

  A total of three endless belts 334 and 338 constituting the second paper transport unit 108 are belts knitted in a net shape like the endless belt 306 of the first paper transport unit 80 described above, and penetrate through the front and back surfaces thereof. Innumerable holes are formed. Each of these endless belts 334 and 338 is formed in an annular shape by heat fusion.

  As shown in FIG. 7, in the second paper transport unit 108, the rotational driving force of the motor 344 supported by the support member 380 is applied to the torque limiter 342 via the gear train 346 and the driving force transmission belt 348. It is transmitted to the attached puller 350, and is transmitted to the drive roll 330 via the torque limiter 342. Further, a tension applying roll 352 that applies tension to the driving force transmission belt 348 is also provided here. The drive roll 330 rotates in response to the rotational driving force from the motor 344 and moves the endless belts 334 and 338 in a circular motion. Here, the motor 344 rotates at a rotational speed that causes the endless belts 334 and 338 to travel slightly faster (about 0.5%) than the prescribed transport speed of the paper P. This is because a slight tension is applied to the paper P entering here, and wrinkles are prevented from occurring on the paper P.

  The torque limiter 342 plays a role of preventing excessive tension on the paper P.

  Inside the endless belts 334 and 338, a wind tunnel member 340 is provided. The wind tunnel member 340 includes an upstream wind tunnel member 354 and a downstream wind tunnel member 356. However, description of the detailed structure of the wind tunnel member 340 is abbreviate | omitted here. The wind tunnel member 340 has a hollow interior in both the upstream side wind tunnel member 354 and the downstream side wind tunnel member 356, and the portion covered by the endless belts 334 and 338 on the upper surface thereof A large number of holes (not shown) communicating with the inside and outside of the cavity are formed. Further, the inside of the support member 380 shown in FIG. 7 is also formed as a cavity, and the cavity is connected to the cavities of both the upstream side wind tunnel member 354 and the downstream side wind tunnel member 356. Then, two openings (not shown) opened inside and outside the support member 380 are formed on the lower surface of the support member 380, and a fan 390 is attached to each of the two openings. These fans 390 have their air inlets facing the opening side. Therefore, when the fan 390 rotates, air is sucked through countless holes of the endless belts 334 and 338, and thereby the endless belts 334 and 338. The sheet P placed on the sheet is attracted to the endless belts 334 and 338 and conveyed.

  Note that a regulating member that regulates the lateral displacement of the endless belts 334 and 338 (a regulating member corresponding to the regulating member 324 shown in FIG. 5 in the above-described first paper transport unit 80) is the same as the first paper transport unit 80. Similarly, it is provided on the lower surface of the wind tunnel member 340 of the second paper transport unit 108. However, the regulating member in the second paper transport unit 108 is not shown because it is located between the support members 380.

  When the paper P is transported toward the second paper transport unit 108 in the X direction shown in FIG. 6, the paper P first comes into contact with the entry region 334 </ b> C of the endless belt 334, and then the endless belt 334. The cooling unit 110 provided on the downstream side of the second paper transport unit 108 is guided by a guide member 400 provided on the downstream side of the endless belts 334 and 338. Proceed to (see FIG. 1).

  In this embodiment, the endless belts 306, 334, 338 and the paper P are evenly in contact with each other by forming the endless belts 306, 334, 338 with a band of fibers made of mesh. At the same time, the heat capacity of the endless belts 306, 334, 338 is reduced. As a result, temperature unevenness that occurs in the paper P conveyed by the endless belts 306, 334, and 338 is suppressed.

  In addition, by suppressing temperature unevenness occurring in the conveyed paper P, image defects are suppressed.

  Specifically, in the first paper transport unit 80 that transports the paper P to the fixing unit 82, the temperature of the endless belt 306 becomes higher than the temperature of the paper P due to the radiant heat of the fixing unit 82. Thereby, in the rubber belt, it is considered that a temperature difference (unevenness) is generated around the hole portion, and the temperature of the paper P conveyed by the sheet material conveying device 80 is locally increased. Since the endless belts 306, 334, and 338, the temperature unevenness generated in the paper P is suppressed. For this reason, image defects are suppressed.

  In the second paper transport unit 108 that transports the paper P discharged from the fixing unit 82 further downstream, the temperatures of the endless belts 334 and 338 are lower than the temperature of the paper P heated by the fixing unit 82. Thereby, in the rubber belt, it is considered that a temperature difference (unevenness) occurs around the hole and the temperature of the paper P conveyed by the second paper conveyance unit 108 is locally lowered. Because of the mesh-like endless belts 306, 334, and 338, temperature unevenness generated on the paper P is suppressed. For this reason, image defects are suppressed.

  Next, the endless belt 306 of the first paper transport unit 80 and the endless belts 334 and 338 of the second paper transport unit 108 will be described. The following description is common to the endless belts 306, 334, and 338. Here, the endless belt 306 will be described.

  FIG. 8 is an enlarged schematic view of an endless belt. Here, FIGS. 8A and 8B are diagrams showing the structures of the outer surface and the inner surface of the endless belt, respectively.

  The endless belt 306 is composed of a knitted fabric made of two types of fibers, urethane fibers 306A and nylon fibers 306B. The urethane fiber 306A has a large coefficient of friction with the paper P, and is used to suppress slippage of the paper P. The urethane fiber 306A corresponds to an example of the first type of fiber referred to in the present invention. The nylon fiber 306B is used to maintain the strength of the endless belt 80. This nylon fiber 306B has a property that the friction coefficient between the wind tunnel member 308 (the wind tunnel member 340 in the case of the second paper transport unit 108) is smaller than the friction coefficient between the urethane fiber 306A and the wind tunnel member 308. I also have. In the present embodiment, as the endless belt 306, a knitted fabric produced by plating knitting, which is one kind of knitting method, using the urethane fiber 306A and the nylon fiber 306B is used. This plating knitting is a knitting method in which two types (or two colors) of fibers are used, and different types (colors) of fibers appear on the front surface and the back surface. The plating knitting itself is a well-known method for knitting a knitted fabric, and further description thereof is omitted here.

  By this plating knitting, urethane fibers 306A are exposed more abundantly than nylon fibers 306B on the outer surface of endless belt 306 shown in FIG. 8A. For this reason, the friction coefficient with the paper P in contact with the outer surface is large, and the slip of the paper P is suppressed.

  On the other hand, nylon fiber 306B is exposed more abundantly than urethane fiber 306A on the inner surface of endless belt 306 shown in FIG. 8B. Therefore, the endless belt 306 (344, 348) easily slides with respect to the wind tunnel member 308 (340) and smoothly moves around.

  Here, a technique is known in which an endless belt is composed of one type of fiber and the coefficient of friction is changed between the outer surface and the inner surface by coating the outer surface or the inner surface. The application of the coefficient of friction has the disadvantage of poor durability over a long period of time. On the other hand, in the case of this embodiment, since two types of fibers having different friction coefficients are used and the friction coefficients of the front and back surfaces are changed by the fibers themselves, the durability is improved.

  Further, in an endless belt provided with a suction port in a rubber belt, the friction coefficient decreases due to accumulation of toner, paper, and dirt on the rubber belt surface over time. In contrast, the endless belt of the present embodiment is a knitted belt made of fibers and is sucked from the back surface, so even if toner or paper dust adheres to the belt surface, it is sucked from the belt surface. The toner is attracted to the inside, and therefore, the accumulation of toner or the like on the surface is suppressed, whereby the reduction of the friction coefficient with time can be suppressed.

  Further, the knitted fabric by the plating knitting is one kind of knitted fabric unlike the woven fabric. For this reason, for example, it is elastically extendable in the horizontal direction of FIG. For the endless belt 106 of the present embodiment, a knitted fabric whose stretchable direction is adjusted to coincide with the traveling direction is used. The endless belt 106 is determined in length so that the endless belt 106 falls within a stretchable range of the knitted fabric when the endless belt 106 is wound around a driving roll or a driven roll. An appropriate tension is applied to 106. In this way, although tension is applied to the endless belt 106 made of this knitted fabric, excessive application of tension to the fiber itself is avoided.

  Here, an endless belt is known which uses not a knitted fabric but a woven fabric in which resin fibers are woven in a cloth shape so that the extending direction of the fibers is oblique to the running direction. In the case of this endless belt, even if it is a woven fabric, elongation can be expected by using it diagonally. However, in this case, after all, an excessive tension is applied to the fiber itself, and the fiber is plastically deformed and stretched over a long period of time, resulting in the loss of the tension of the endless belt. In this embodiment, the endless belt 106 is a knitted fabric whose stretch direction matches the running direction, so that less stress is applied to the fiber itself, and the tension of the endless belt 106 is maintained over a long period of time. The

  In this embodiment, a combination of urethane fiber and nylon fiber is used. However, a combination of other types of fibers considering the friction coefficient and durability may be used.

  Here, although the plating knitting is illustrated, the plating knitting is not necessarily employed. What is necessary is just a knitted fabric in order to make it elastic. In addition, as a method of exposing different types of fibers on the outer surface and the inner surface, for example, two types of fibers may be separately knitted and bonded to the front and back.

  In addition, here, the knitted belt composed of two kinds of fibers is exemplified, but in the present invention, the first fiber for adjusting the friction coefficient of the front surface, the second fiber as the base material, and the friction coefficient of the back surface are adjusted. A knitted belt made of three or more kinds of fibers, such as a knitted belt made of the third fiber, may be used.

  Further, here, the image forming apparatus of the type shown in FIG. 1 has been described as an example of the image forming apparatus of the present invention, but the image forming apparatus of the present invention is limited to the type of image forming apparatus shown in FIG. The image forming apparatus may be of any type that forms a toner image on a sheet using toner and fixes the toner image on the sheet.

  Here, an example is shown in which the paper conveying apparatus of the present invention is applied to the type of image forming apparatus shown in FIG. 1, but the paper conveying apparatus of the present invention can be applied to any type of image forming apparatus. Good. Furthermore, the sheet conveying apparatus of the present invention is not only applied to the image forming apparatus, but can be widely applied to applications for conveying sheets.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 80 1st paper conveyance unit 82 Fixing unit 108 2nd paper conveyance unit 302,330 Drive roll 304,332,336,396 Followed roll 306,334,338 Endless belt 306A Urethane fiber 306B Nylon fiber 308, 340 Wind tunnel member

Claims (5)

An endless belt made of knitted fabric,
A rotating member around which the endless belt is wound and rotated to rotate the endless belt;
An air suction port is formed in a portion of the endless belt that is in contact with the inner surface of the endless belt and faces the forward path side of the endless belt, and sucks air so that the paper to be conveyed is transported to the outer surface of the endless belt forward path side. A paper conveyance device comprising a wind tunnel member to be adsorbed.   The endless belt has a friction coefficient between the wind tunnel member and at least the first type of fiber having a relatively high friction coefficient with the paper and relatively abundantly exposed on the outer surface in contact with the paper. 2. A knitted fabric using a plurality of types of fibers, including a second type of fibers exposed relatively abundantly on an inner surface that is relatively low and in contact with the wind tunnel member. Paper transport device.   3. The paper conveying apparatus according to claim 2, wherein the endless belt is constituted by a knitted fabric knitted by plating knitting.   4. The sheet conveying device according to claim 1, wherein the first type of fiber is a urethane fiber, and the second type of fiber is a nylon fiber. 5. A toner image forming unit that forms a toner image on paper;
A fixing unit for fixing the toner image on the paper on which the toner image is formed on the paper;
A first conveying unit that conveys a sheet on which a toner image is formed in the toner image forming unit to the fixing unit;
A second transport unit that further transports the paper on which the toner image is fixed in the fixing unit,
At least one of the first transport unit and the second transport unit transports a sheet using the sheet transport apparatus according to any one of claims 1 to 4. Image forming apparatus.

Images