JP2016183053A - Sheet transport device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet transport device capable of eliminating wrinkle and twist of a sheet being transported while transporting the sheet.SOLUTION: A sheet transport device comprises: a sheet storage portion 11 for storing a sheet bundle 1; sheet ascending and descending member driving means 18 for vertically ascending and descending the sheet bundle 1; and two electrostatic attraction belt units 131 and 132 located above the sheet bundle 1 and including an endless electrostatic attraction belt 13A for electrostatically attracting the sheets as an electrostatic attraction belt device 13. The electrostatic attraction belt units 131 and 132 are individually spaced from each other and arranged to form a space K, and the two adjoining electrostatic attraction belts 13A and 13A are arranged such that the space at a downstream transportation side end of the sheets is made larger than the spacing at an upstream transportation side end of the sheets. An uppermost sheet 1A is widened in a width direction while being transported by the electrostatic attraction belts 13A and 13A so that wrinkle and twist are eliminated.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a sheet conveying apparatus used for an image forming apparatus such as a facsimile, a printer, a copying machine, a multifunction machine having at least two of these functions using an electrophotographic system, an electrostatic recording system, and the like, and an image provided with the same. The present invention relates to a forming apparatus.

  As a sheet conveying apparatus used in an image forming apparatus such as a copying machine or a printer, an air suction type sheet conveying apparatus shown in FIG. 16 is widely known (see Patent Document 1).

  A sheet conveying apparatus 101 shown in FIG. 16 includes a sheet suction conveying unit 112 including a sheet feeding belt 112C above the sheet storage unit 111, and includes a plurality of sheets stacked on the sheet storage unit 111. The sheet 102A at the top of the sheet bundle 102 in the vertical direction (hereinafter referred to as “uppermost sheet 102A”) is attracted to the sheet feeding belt 112C one by one by the air suction unit 113, and the uppermost sheet 102A is moved to a predetermined position. It is comprised so that it may convey. An air blowing unit 114 is provided on the downstream side of the sheet storage unit 111, and the stacked sheet bundle 102 is separated by blowing air to one end of the sheet bundle 102.

  A downstream end uppermost sheet detecting unit 115 is provided on the downstream side of the sheet conveyance, and an upstream uppermost sheet detecting unit 116 is not affected by the sheet blowing upstream by the air blowing unit 114. Is provided. The upstream uppermost sheet detection means 116 includes a position detection unit 116A and a position detection lever 116B. The sheet storage unit 111 is connected to the sheet lifting / lowering means 118 and can be lifted / lowered. When the uppermost sheet 102A comes into contact with the position detection lever 116B, the position detection lever 116B is configured to be pushed vertically upward. A large number of suction holes (not shown) are formed on the entire surface of the paper feed belt 112C. The uppermost sheet 102A is adsorbed to the paper feed belt 112C via the suction holes and the air suction unit 113, and Transport.

  The sheet conveying operation with the above configuration is as follows. First, before the sheet conveying operation starts, the sheet elevating member 111A is raised by the sheet elevating unit 118, and the downstream end of the uppermost sheet 102A of the stacked sheets 102 is detected by the uppermost sheet detecting unit 115 at the downstream end. . The detection position of the uppermost sheet 102A is stored in the upstream uppermost sheet detection means 116 as a reference position.

  Next, as shown in FIG. 17, separation air A is blown to the sheets 102 stacked by the air blowing unit 114 to separate the stacked sheet bundles 102. The uppermost sheet 102A is attracted to the sheet feeding belt 112C by the air suction unit 113, the sheet feeding belt 112C is rotated, and the attracted sheet is conveyed to a predetermined position. When the sheet 102 in the sheet storage unit 111 is reduced by sheet conveyance, the vertical position of the uppermost sheet 102A is lowered, and the upstream uppermost sheet detection unit 116 is out of the reference position stored, the sheet lifting unit 118 raises the sheet. Let When the vertical position of the uppermost sheet 102A is not lowered so much and the upstream uppermost sheet detecting means 116 is detecting the reference position, the sheet conveying operation is continued.

  There are many known air suction type sheet conveying apparatuses as described above. However, in the example shown in FIGS. 16 and 17, all of them are negative pressure by sucking the air suction portion 113 to make it vacuum. Is generated, and the uppermost sheet 102A is adsorbed to the sheet feeding belt 112C. Therefore, it is considered that the sheet surface is damaged by an excessive negative pressure. May be transferred.

  That is, in the case of air adsorption, the adsorption power is strong, so even if the separation air A is blown toward the belt from the downstream side, there is no problem that the topmost paper is peeled off, and the second and subsequent papers are pushed down reliably. However, since a recess is formed in the sheet when the sheet is adsorbed in an adsorption hole formed on the belt surface by air adsorption, the electrostatic adsorption belt can be electrostatically adsorbed with a weaker adsorbing force. A method of using is proposed.

  Since the sheet conveying apparatus using the electrostatic adsorption belt uses an electrostatic adsorption force (Coulomb force) for adsorbing the uppermost sheet, there is no occurrence of a concave portion on the sheet surface unlike the air suction type adsorption system.

  However, in the conventional electrostatic attraction type sheet conveying device, when the sheet is bent and stacked in the sheet storage unit, or when the sheet absorbs moisture and the sheet is bent in a natural stacking state, When the sheet is adsorbed, deformation such as wrinkles or twists may occur. Such wrinkles, twists, etc. also occur due to the fact that the uppermost sheet is fluttered by the flow of air when the uppermost sheet is air-separated and the contact state with the electrostatic adsorption belt becomes poor. In this case, there is a problem that the sheet is conveyed to the image forming unit while the deformation of the uppermost sheet is maintained.

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet conveying apparatus and an image forming apparatus that can eliminate wrinkles and deviations of a conveyed sheet during conveyance.

  A sheet conveying apparatus according to the present invention includes a sheet storage unit that stores a sheet bundle, a sheet elevating unit that vertically moves the sheet bundle, and an endless unit that is positioned above the sheet bundle and electrostatically attracts the uppermost sheet. An adsorption belt device including a plurality of electrostatic adsorption belts, and a gap is provided between the electrostatic adsorption belts of the adsorption belt device so that at least two adjacent electrostatic adsorption belts are It is characterized in that the interval on the downstream side of conveyance of the uppermost sheet is larger than the interval on the upstream side of conveyance of the sheet.

  According to the present invention, the electrostatic attraction belt spreads the sheet in the width direction while the sheet is conveyed by the electrostatic attraction belt, and the wrinkles and twists of the sheet can be eliminated.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus that can be equipped with a sheet conveying apparatus according to the present invention. 1 is a side view illustrating a sheet conveying apparatus according to a first embodiment of a sheet conveying apparatus according to the present invention. It is a top view which shows the same sheet conveying apparatus. It is a schematic diagram which shows the arrangement | positioning state of the electrostatic adsorption belt of the sheet conveying apparatus. The sheet conveying state in the sheet conveying apparatus is shown. (A) is a schematic diagram showing a case where no air reflecting plate is provided, and (b) and (c) are conveying states when an air reflecting plate is provided. It is a schematic diagram shown sequentially. The sheet conveyance state in the sheet conveying apparatus is shown, and (a) and (b) are schematic views sequentially illustrating the conveyance state. FIG. 1 shows an electrode-embedded electrostatic chucking belt of a sheet conveying apparatus, (a) is a schematic diagram showing the configuration, and (b) is a position of an exhaust hole provided on the chucking surface of the electrostatic chucking belt with respect to the uppermost sheet. It is a schematic diagram which shows. The figure which shows the table which showed the combination of the distance and the air quantity according to sheet basis weight and sheet size with respect to different kinds of sheets of non-coated paper represented by high-quality paper and coated paper represented by coated paper It is. The figure which shows the table which showed the combination of the distance and the air quantity according to sheet basis weight and sheet size with respect to different kinds of sheets of non-coated paper represented by high-quality paper and coated paper represented by coated paper It is. FIG. 3 shows an arrangement state of an electrostatic attraction belt of a sheet conveying apparatus according to Embodiment 2 of a sheet conveying apparatus according to the present invention, (a) is a schematic diagram showing a first state, and (b) is a second figure. The schematic diagram which shows a state, (c) is a schematic diagram which shows a driving force transmission mechanism. FIG. 7 shows positions of a driving roller and a driven roller of a sheet conveying apparatus according to Embodiment 3 of the sheet conveying apparatus according to the present invention, (a) is a schematic diagram showing an adsorption position, and (b) is a schematic showing a conveying position. FIG. FIG. 9 shows positions of a driving roller and a driven roller of a sheet conveying apparatus according to a fourth embodiment of the sheet conveying apparatus according to the present invention, where (a) is a schematic diagram showing an adsorption position, and (b) is a schematic showing a conveying position. FIG. It is a side view which shows the sheet conveying apparatus which concerns on Embodiment 5 of the sheet conveying apparatus which concerns on this invention. It shows the action of the conveyance guide plate of the sheet conveying apparatus, (a) is a view showing the state of adsorbing and conveying the uppermost sheet from the right side of FIG. 13, (b) is a view from the pushed-down air blower FIG. 6 is an enlarged view showing a state in which a part of air acts as pushed-down air that is reflected downward from the lower surface of the sheet in the conveyance guide plate and flows downward. It shows another example of the conveyance guide plate of the sheet conveyance device, (a) is a diagram showing an example of forming a vent hole of the conveyance guide plate, (b) is a diagram showing the shape and position of the conveyance guide plate. is there. It is a schematic diagram which shows an example of the conventional air suction type sheet conveying apparatus. FIG. 17 is a schematic diagram illustrating an operation state of the sheet conveying apparatus illustrated in FIG. 16.

  A sheet conveying apparatus and an image forming apparatus according to an embodiment for carrying out the present invention will be described.

  FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus that can be equipped with a sheet conveying apparatus according to the present invention. Note that the image forming apparatus to be implemented in the present invention is not limited to the one shown in the figure, and the image forming apparatus such as a copying machine, a facsimile apparatus, an apparatus having a function of a multifunction machine having a copying function and a facsimile function, etc. Various devices that perform the above are targeted.

  In FIG. 1, a copying machine 100 as an example of an image forming apparatus separates a document from a bundle of documents placed on a document tray 110a and automatically feeds the document to a contact glass on a document reading unit 120. 110, a document reading unit 120 that reads a document conveyed on the contact glass by the automatic document conveyance device 110, and an image read by the document reading unit 120 is formed on a sheet material fed from the sheet feeding unit 130. An image forming unit (image forming unit) 140 and a sheet bundle 1 in which a plurality of sheet materials are laminated. Further, the copying machine 100 includes a paper feeding unit 130 that feeds the uppermost sheet 1A positioned from the sheet bundle 1 to the image forming unit 140. In this embodiment, the image forming unit 140 and the paper feeding unit 130 can be divided, but a configuration other than that may be used.

  The sheet feeding unit 130 includes a sheet feeding cassette 150 that stacks a sheet bundle 1 composed of a plurality of sheets, and a sheet separation sheet feeding device 160 that separates and conveys the uppermost sheet 1A from the sheet bundle 1 on the sheet feeding cassette 150. Is included.

  The sheet separated and fed by the sheet separating / feeding device 160 is transported on the transport path 170, and the sheet transported on the transport path 170 is transported by the transport roller pair 180 to be transferred to the transfer roller. The toner image formed by the image forming unit 140 is transferred by 190, this toner image is thermally transferred by the fixing device 200, and discharged to the discharge tray 220 by the discharge roller pair 210.

  The image forming unit 140 includes four image forming units 230 (230Y (yellow), 230C (cyan), 230M (magenta), 230BK (black)), an intermediate transfer belt 240 that is a transfer belt, and an exposure device 250. It is configured.

  The exposure apparatus 250 converts color-separated image data input from a personal computer, a word processor, or the like, or image data of an original read by the original reading unit 120 into a signal for driving a light source, and accordingly, each laser light source unit. A semiconductor laser is driven to emit a light beam.

  The image forming units 230Y, 230C, 230M, and 230BK form images of different colors (toner images), and the image forming units 230Y, 230C, 230M, and 230BK are rotated in the clockwise direction. The image forming apparatus includes a photosensitive member 260 (260Y, 260C, 260M, and 260BK) that is an image carrier, a charging unit 270, a developing unit 280, a cleaning unit 290, and the like disposed around the photosensitive member 260.

  The photoreceptor 260 is formed in a cylindrical shape and is driven to rotate by a drive source (not shown). A photosensitive layer is provided on the outer peripheral surface portion of the photoconductor 260, and a light beam indicated by a broken line emitted from the exposure apparatus 250 is spot-irradiated on the outer peripheral surface of the photoconductor 260, whereby the outer peripheral surface of the photoconductor 260 is exposed. The electrostatic latent image corresponding to the image information is written.

  The charging unit 270 uniformly charges the outer peripheral surface of the photoconductor 260, and a contact type is used for the photoconductor 260. The developing unit 280 supplies toner to the photosensitive member 260, and the supplied toner adheres to the electrostatic latent image written on the outer peripheral surface of the photosensitive member 260, whereby the electrostatic latent image on the photosensitive member 260 is changed. A toner image is visualized, and a non-contact type is used for the photoreceptor 260.

The cleaning unit 290 cleans residual toner adhering to the outer peripheral surface of the photoconductor 260 and employs a brush contact type in which a brush contacts the outer peripheral surface of the photoconductor 260.

  The intermediate transfer belt 240 is composed of an endless belt formed using a resin film or rubber as a base, and the toner image formed on the photosensitive member 260 is transferred to the intermediate transfer belt 240. The toner image is transferred onto the sheet by the transfer roller 190.

<Embodiment 1>
Next, the sheet conveying apparatus 10 will be described. 2 is a side view showing the sheet conveying apparatus according to the first embodiment of the sheet conveying apparatus according to the present invention, FIG. 3 is a plan view showing the sheet conveying apparatus, and FIG. It is a schematic diagram which shows a state.

  As shown in FIG. 2, the sheet conveying apparatus 10 includes a sheet storage unit 11, a sheet elevating member 12, an electrostatic adsorption belt device 13, a protruding member 13F, an air blowing unit 14, and an electrostatic adsorption belt driving unit 13E. A sheet elevating / lowering member driving means 18, conveying direction side end regulating members 15 </ b> A and 15 </ b> B of the sheet bundle 1 shown in FIG. 6, a control means 19, and an air reflecting plate 20.

  The sheet elevating member 12 includes a bottom surface portion 12A disposed horizontally, and a sheet bundle 1 composed of a plurality of sheets stacked on the bottom surface portion 12A can be stacked. In the sheet storage unit 11, the drive is controlled by the control unit 19, and the sheet lifting member driving unit 18 drives the sheet lifting member 12 up and down. By driving the sheet elevating member driving means 18, the sheet elevating member 12 is raised and lowered, and the sheet bundle 1 in the sheet storage unit 11 can be raised and lowered.

  As shown in FIG. 3, the electrostatic adsorption belt device 13 includes a plurality of electrostatic adsorption belt units 131 and 132 in this example. Each of the electrostatic attraction belt units 131 and 132 is configured by winding the electrostatic attraction belt 13A around the driving roller 13B and the driven roller 13C. The driving rollers 13B and 13B of the electrostatic attraction belt units 131 and 132 are connected by a driving force transmission mechanism 24A such as a universal joint, and the driven rollers 13C and 13C are connected by a driving force transmission mechanism 24B such as a universal joint. The electrostatic attraction belt driving means 13E connected to one of the drive rollers 13B and 13B is driven and controlled by the control means 19, so that the electrostatic attraction belt 13A of the electrostatic attraction belt units 131 and 132 is rotationally driven.

  The electrostatic adsorption belt units 131 and 132 are arranged so that the electrostatic adsorption belts 13A and 13A spread toward the upstream side of sheet conveyance. That is, as shown in FIG. 4, the electrostatic attraction belt unit 131 and the electrostatic attraction belt unit 132 have a gap K2 at the downstream end of the sheet conveyance larger than an interval K1 at the upstream end of the conveyance. It arrange | positions on both sides of the clearance gap K. The electrostatic attraction belt unit 131 and the electrostatic attraction belt unit 132 are arranged symmetrically with respect to the sheet conveyance center line 23, and the installation axes 131A and 312A of the electrostatic attraction belt units 131 and 132 form an angle α. Note that the angle α cannot be changed in the sheet conveying apparatus 10. In the sheet conveying apparatus 10, the electrostatic attraction belt units 131 and 132 are fixedly arranged in the vertical direction with respect to the sheet bundle 1.

  In the sheet conveying apparatus 10 according to the present embodiment, the uppermost sheet 1A that has floated advances so that the left and right suction locations of the sheet move away from the sheet conveyance center line 23 as it proceeds to the conveyance downstream side, as shown in FIG. The uppermost sheet 1A receives a force extending in the width direction from the electrostatic adsorption belts 13A and 13A, and stretches wrinkles, twists and the like generated in the uppermost sheet 1A. Further, since the electrostatic attraction belt units 131 and 132 are arranged symmetrically with respect to the conveyance center line 23, the right and left conveyance speed of the uppermost sheet 1A becomes asymmetric during conveyance and the sheet rotates within the conveyance plane. It is possible to prevent the malfunction of the sheet behavior such as.

  The configuration of the electrostatic adsorption belt will be described. FIGS. 7A and 7B show an electrode-embedded electrostatic adsorption belt of a sheet conveying apparatus. FIG. 7A is a schematic diagram showing the configuration, and FIG. 7B is an exhaust provided on the adsorption surface of the electrostatic adsorption belt with respect to the uppermost sheet. It is a schematic diagram which shows the position of a hole. The electrostatic adsorption belt 13A is a belt made of a sheet-like medium in which a plurality of electrodes 21 as shown in FIG. In the plurality of electrodes 21, positive electrodes 21A and negative electrodes 21B are alternately arranged. When a voltage is applied to these electrodes 21 by the electrostatic attraction belt power supply device 13D, dielectric polarization occurs, and the attraction surface of the uppermost sheet 1A is polarized. Therefore, an electrostatic attraction force (Coulomb force) between the electrodes 21 and the electrostatic attraction belt 13A. Will occur.

  The uppermost sheet 1A attracted to the electrostatic attraction belt 13A by the electrostatic attraction force is driven by the electrostatic attraction belt driving means 13E in the state of being attracted to the electrostatic attraction belt 13A as shown in FIGS. 5B and 5C. When the electrostatic attraction belt 13A rotates, the uppermost sheet 1A is conveyed to a position where image forming means (not shown) is disposed.

  Further, in this configuration, the electrostatic attraction belt 13A in which the electrode 21 is covered with the insulating layer 22 is used. However, an electrostatic attraction force may be generated by applying an electric charge on the electrostatic attraction belt. You may provide the provision means.

  As shown in FIG. 3, the air blower 14 is located near the side 1B of the uppermost sheet 1A, and the blower opening is provided at a position facing the side 1B. For example, as shown in FIG. 6, it is provided immediately below the gap K between the electrostatic attraction belt units 131 and 132. The direction and position are determined so that the air blown from the air blower 14 is directed to the gap K. At this time, as will be described later, the air reflector 20 reflects the air from the air blowing section 14 and improves the air separation efficiency.

  By blowing air by the air blowing unit 14, the uppermost sheet 1A and the sheet in the vicinity of the side 1B of the uppermost sheet 1A are levitated so as to approach or come into contact with the electrostatic adsorption belt 13A. Air flows and a plurality of sheets can be separated from each other.

  As shown in FIG. 5B and FIG. 6A, the air passing through the vicinity of the suction surface passes through the gap K between the electrostatic suction belts 13A and 13A before the uppermost sheet is sucked. The uppermost sheet 1A can be favorably adsorbed to the belt 13A.

  After adsorbing the top sheet 1A, as shown in FIG. 5C, the gap K between the electrostatic attraction belts 13A and 13A is blocked by the top sheet 1A, so this air enters between the top sheet 1A and the next sheet. , Separation between sheets can be performed satisfactorily. At this time, as shown in FIG. 6B, a protrusion member 13F, which will be described later, forms a gap between the uppermost sheet 1A and the next sheet, and helps to separate them.

  In addition, in this structure, although the air ventilation part 14 was arrange | positioned only in the position facing the edge | side 1B, it can arrange | position to the position where the edge | side 1D and the edge | side 1E oppose in one place or multiple places.

  The air reflector 20 is disposed on the 14 side of the gap K. As shown in FIG. 5, the air reflector 20 receives a part of the air blown from the air blower 14 and efficiently separates the uppermost sheet 1 </ b> A.

  Here, the operation of the air reflector 20 will be described. In the configuration in which air from the air blowing unit 14 is blown into the gap K of the electrostatic adsorption belt 13A and the uppermost sheet 1A is adsorbed by the electrostatic adsorption belts 13A and 13A, the adsorbed uppermost sheet closes the gap K of the electrostatic adsorption belt. It will be. At this time, the air blower 14 blown toward the gap K between the electrostatic adsorption belts 13A and 13A is installed at a position where the adsorbed uppermost sheet 1A is pushed up from below. As shown to (a), since the sheet | seat under levitation lower than the top sheet | seat 1A is also pushed up, the floatation effect | action of a sheet | seat will increase.

  The thinner the sheet, the stronger this tendency. The air separation between the uppermost sheet 1A and the sheet lower than the uppermost sheet 1A after the adsorption of the uppermost sheet 1A is inferior to this levitation action, and the separation can be performed well. There is a problem that it leads to double feeding.

  In order to solve this, it is necessary to install the air blower 14 in a position as far as possible from the sheet bundle 1 in this state to reduce the influence on the sheet bundle that is being lifted. For this reason, in the sheet conveying apparatus 10 according to the present embodiment, the air blower 14 is disposed at a position away from the air blowing unit 14 and the air reflecting plate 20 is provided in a part of the gap K between the electrostatic adsorption belts 13A and 13A. A part of the air blown by the air blowing unit 14 is applied.

  With this configuration, before adsorption of the uppermost sheet 1A, as shown in FIG. 5 (b), a part of the air blown from the air blowing section 14 hits the air reflecting plate 20, but the air flowing upward between the belts Along the flow, air escapes to the gap K between the electrostatic adsorption belts 13A and 13A.

  Further, after the adsorption of the uppermost sheet 1A, as shown in FIG. 5 (c), the air flow path that has escaped into the gap K is blocked by the uppermost sheet, so that the air hitting the air reflector 20 is the uppermost sheet 1A. And air enters between lower sheets than the uppermost sheet 1A.

  By arranging the air blowing unit 14 and the air reflecting plate 20 in this way, the position of the air blowing unit 14 can be installed at a position further away from the sheet bundle, and the sheet of the sheet is blown by air as in the previous problem. The levitation action is no longer greater than the separation action. In addition, when the air blowing section 14 is moved away from the sheet bundle 1 and the levitation action is insufficient, one or more additional air blowing sections for levitation are added at positions facing the sides 1B, 1D, and 1E. May be arranged.

  The air reflecting plate 20 is a position having a gap of 0.5 mm or more from the suction surface in the opposite direction to the sheet, and the leading end of the air reflecting plate 20 is a position 1 mm or more upstream from the leading end of the uppermost sheet, and has a flat length in the conveying direction. Shall. As the material, a resin having good slidability is used. However, the material is not limited as long as the material does not place a burden on the sheet even if the sheet is in contact with the sheet during conveyance.

  As shown in FIGS. 2 and 3, the sheet bundle 1 includes a pair of sides composed of a first side 1B and a second side 1C, and a pair of sides composed of a third side 1D and a fourth side 1E. A rectangular shape defined by the sides. The side 1D and the side 1E are directed in a direction connecting the driving roller 13B and the driven roller 13C, the side 1B is located on the downstream side of the right sheet conveyance in FIG. 3, and the side 1C is the left side sheet conveyance in FIG. Located upstream.

  The protruding member 13F is disposed between the electrostatic attraction belt units 131 and 132 so as to protrude downward from the attraction surface of the electrostatic attraction belt 13A. The protruding member 13F includes a rotating member that rotates with the conveyance of the sheet in order to contact the uppermost sheet 1A when the uppermost sheet 1A is conveyed. For this reason, the resistance at the time of conveyance can be minimized, and the conveyance can be performed without damaging the uppermost sheet 1A.

  When the uppermost sheet 1A floats with air as shown in FIG. 6A and the uppermost sheet 1A covers the gap K of the electrostatic adsorption belt as shown in FIG. 1A comes into contact with the protruding member 13F and deforms. Thereby, a space is formed between the uppermost sheet 1A and the next sheet, and air enters the space, so that the uppermost sheet 1A and the next sheet can be more reliably separated.

  In addition, the protruding amount of the protruding member 13F can be changed by the protruding amount changing means 13G from the electrostatic attraction belt 13A. For example, for a sheet having a large basis weight, such as a sheet that is difficult to be deformed and attracted, the deformation of the sheet is reduced by making the protruding amount smaller than other sheet types. For this reason, the uppermost sheet 1A can be satisfactorily separated without hindering the uppermost sheet 1A from being attracted to the electrostatic attraction belt 13A.

  This protrusion member 13F can change the protrusion amount from −5 mm to 5 mm according to the sheet basis weight and size by the protrusion amount changing means 13G. For example, for a sheet having a large basis weight, the sheet is difficult to be deformed and difficult to be adsorbed, and the deformation of the sheet can be reduced by making the amount of protrusion smaller than the other sheet types, thereby preventing the adsorption to the electrostatic attraction belt 13A. In addition, separation between sheets can be performed well.

  The control unit (not shown) of the projection amount changing unit 13G is configured to adjust the electrostatic adsorption belt 13A adsorption surface at the time of adsorption of the uppermost sheet 1A according to the sheet basis weight, the sheet type, and the sheet size stacked in the sheet storage unit 11. A table for changing the distance d of the uppermost sheet 1A, the air amount e blown from the air blowing unit 14 that separates the uppermost sheet, and the air amount e blown from the air blowing unit 14 that pushes down the contact sheet is accumulated. ing.

  8 and 9 show different combinations of the sheet basis weight, the sheet size, and the amount of air and the amount of air for different types of non-coated paper (typically fine paper) and coated paper (typically coated paper). It is a figure which shows the shown table. 8 (a) and 8 (b) show the uppermost sheet according to the sheet basis weight and the sheet size for different types of sheets of non-coated paper typified by fine paper and coated paper typified by coated paper. It is the table which showed the combination of the space | interval d of 1A and the electrostatic adsorption belt 13A, and the air quantity e ventilated from the air ventilation part 14. FIG. FIGS. 9A and 9B are tables showing the protruding amount f of the protruding member 13F corresponding to the sheet type. In the operation of adsorbing the uppermost sheet 1A to the electrostatic attraction belt 13A in a state where the uppermost sheet 1A is floated by the air blower 14, even when the sheet basis weight, the sheet type, and the sheet size are changed, the most appropriate combination of the distance d and the air amount e By selecting the protruding amount f of the protruding member from the table, the sheet conveying operation can be performed satisfactorily.

8 and 9 may have different values or the same values depending on the sheet basis weight, the sheet type, and the sheet size. For example, if it is a sheet conveying apparatus 10 capable of exhibiting sufficient performance at a boundary between a sheet size of less than A3 and A3 or more,
d1ax = d1bx,
d1ay = d1by,
d1az = d1bz,
e1ax = e1bx,
e1ay = e1by,
e1az = e1bz
Etc.

  In the sheet conveying apparatus 10 of the present embodiment, the uppermost sheet 1A is separated and conveyed from the sheet bundle 1 as follows.

  (1) The sheet bundle 1 stacked in the sheet storage unit 11 is raised by the sheet lifting member driving means 18. At this time, the electrostatic attraction belt 13A adsorption surface and the uppermost sheet 1A are controlled so as to have a set interval d.

  (2) The air blowing unit 14 is operated, and at the same time, the electrostatic attraction belt power supply device 13D is operated to electrostatically adsorb the uppermost sheet 1A to the electrostatic attraction belt 13A. At this time, the air from the air blowing section 14 floats the upstream side of the transport of the uppermost sheet 1A and separates it from the sheet bundle until it can be attracted by the electrostatic attraction belt 13A (FIG. 5B, FIG. 6). (A)). A part of the air blown from the air blower 14 hits the air reflection plate 20, but the air escapes into the gap K between the electrostatic adsorption belts 13A and 13A along the upward air flow between the belts.

  (3) The electrostatic chucking belt driving unit 13E is operated to rotate the electrostatic chucking belts 13A of the electrostatic chucking belt units 131 and 132 to convey the uppermost sheet 1A (FIG. 6B). At this time, since the uppermost sheet 1A is expanded in the width direction, wrinkles and twists are eliminated. Even when the uppermost sheet 1A being conveyed covers the gap K between the two electrostatic adsorption belts 13A and 13A, a gap is formed between the uppermost sheet 1A and the second sheet by the protruding member 13F. Air flows into the gap and the two sheets are separated (FIG. 6B). Further, the air from the air blowing unit 14 is reflected by the air reflecting plate 20, and the air enters between the uppermost sheet 1A and the lower sheet than the uppermost sheet 1A. Thereby, the uppermost sheet 1A and the lower sheet than the uppermost sheet 1A are well separated.

  (4) The electrostatic attraction belt power supply device 13D and the electrostatic attraction belt driving means 13E are stopped at the same time as the leading edge reaches the next transport roller.

  (5) The control unit controls the sheet elevating member driving means 18 so that the electrostatic attraction belt 13A adsorption surface and the uppermost sheet 1A have the set distance d.

  (6) Thereafter, the operation (2) to the operation (5) are continuously repeated until all the sheets in the sheet storage unit 11 are conveyed or a signal indicating completion of the sheet conveying operation is received.

  As described above, according to the sheet conveying apparatus 10 according to the present embodiment, the left and right sides of the sheet move away from the sheet conveyance center line 23 as the levitated uppermost sheet advances toward the conveyance downstream side. The left and right sides of the sheet are widened, and the distortion generated on the floating uppermost sheet can be extended to eliminate deformations such as wrinkles and twists.

<Embodiment 2>
Next, a sheet conveying apparatus according to Embodiment 2 of the sheet conveying apparatus according to the present invention will be described. 10A and 10B show an arrangement state of the electrostatic attraction belt of the sheet conveying apparatus according to the second embodiment of the sheet conveying apparatus according to the present invention. FIG. 10A is a schematic diagram showing a first state, and FIG. The schematic diagram which shows a 2nd state, (c) is a schematic diagram which shows a driving force transmission mechanism. The sheet conveying apparatus 30 according to the second embodiment can change an angle between which the conveyance center line 23 of the electrostatic attraction belt units 131 and 132 is sandwiched.

  In the sheet conveying apparatus 30, the two electrostatic attraction belt units 131 and 132 are arranged so that the installation axes 131A and 312A of the electrostatic attraction belts 13A and 13A are symmetrical with respect to the sheet conveyance center line 23, for example, an angle α ( Belt position changing means for changing from FIG. 10 (a) to angle β (FIG. 10 (b)) is provided. As the belt position changing means, a device having a screw mechanism and capable of changing the angle formed by the electrostatic adsorption belt units 131 and 132 or a device that can be changed electrically can be adopted.

  In the sheet conveying device 30, the driving rollers 13B and 13B of the two adjacent electrostatic adsorption belt units 131 and 132 are connected by the driving force transmission mechanism 24A and the driven rollers 13C and 13C are connected by the driving force transmission mechanism 24B. These driving force transmission mechanisms 24A and 24B are constant velocity universal joints. Thereby, the electrostatic attraction belts 13A and 13A of the electrostatic attraction belt units 131 and 132 are driven at the same speed.

  The driving force transmission mechanisms 24A and 24B can employ the following configurations. For example, as shown in FIG. 10 (c), the spline joint 25 is composed of a female spline 25A and a male spline 25B, and is provided on the free end side of the female spline 25A and the female spline 25A. The constant velocity joints 27A and 27B connected to the roller 13B and the drive gear 28A disposed on the male spline 25B of the spline joint 25 are configured.

  The drive gear 28 is connected to the electrostatic attraction belt drive means 13E by a rotation conduction device 28B such as a gear train, and the drive rollers 13B and 13B are driven to rotate. Thereby, even if the angle of the electrostatic attraction belt units 131 and 132 is changed, the electrostatic attraction belts 13A and 13A can be driven at the same rotational speed.

  According to the sheet conveying apparatus 30 according to the present embodiment, when conveying a sheet 1F having a smaller width size W2 as illustrated in FIG. 10B, the sheet 1G having a larger width size W1 than the sheet 1F is conveyed. It is assumed that the angle β is larger than the angle α (β <α). Thereby, the ratio of the area which the sheet | seat 1F and the electrostatic adsorption belt 13A contact | abut can be enlarged, and the stable conveyance can be performed. The change of the angle of the electrostatic attraction belt units 131 and 132 can be changed by the sheet friction coefficient as well as the size of the sheet. Further, the angle type of the electrostatic attraction belt units 131 and 132 can be changed by automatically detecting the sheet size type.

<Embodiment 3>
Next, a sheet conveying apparatus according to Embodiment 3 of the sheet conveying apparatus according to the present invention will be described. 11A and 11B show the positions of the driving roller and the driven roller of the sheet conveying apparatus according to Embodiment 3 of the sheet conveying apparatus according to the present invention. FIG. 11A is a schematic diagram showing the suction position, and FIG. 11B is the conveying position. It is a schematic diagram which shows. In the sheet conveying apparatuses according to Embodiments 1 and 2 described above, the positions of the driving roller 13B and the driven roller 13C are fixed at the same position in the vertical direction. In the sheet conveying apparatus 40 according to the third embodiment, both the driving roller 13B and the driven roller 13C are configured to reciprocate the suction position shown in FIG. 11 (1) and the conveying position shown in FIG. 11 (2) in the vertical direction. did. Other configurations are the same as those of the sheet conveying apparatus according to the first or second embodiment.

<Embodiment 4>
Next, a sheet conveying apparatus according to Embodiment 4 of the sheet conveying apparatus according to the present invention will be described. 12A and 12B show the positions of the driving roller and the driven roller of the sheet conveying apparatus according to the fourth embodiment of the sheet conveying apparatus according to the present invention. FIG. 12A is a schematic diagram showing the suction position, and FIG. 12B is the conveying position. It is a schematic diagram which shows. In the sheet conveying apparatus 50 according to the fourth embodiment, the position of the driving roller 13B, the driven roller 13C, and the driven roller 13C is set to the suction position illustrated in FIG. 12A and the conveying position illustrated in FIG. As much as possible, it was configured to reciprocate in the vertical direction. Other configurations are the same as those of the sheet conveying apparatus according to the first or second embodiment.

<Embodiment 5>
Next, a sheet conveying apparatus according to Embodiment 5 of the sheet conveying apparatus according to the present invention will be described. FIG. 13 is a side view showing a sheet conveying apparatus according to Embodiment 5 of the sheet conveying apparatus according to the present invention, FIG. 14 shows the operation of the conveying guide plate of the sheet conveying apparatus, and (a) shows the uppermost sheet. FIG. 13B is a diagram showing the state of being sucked and transported as viewed from the right side of FIG. 13. FIG. 13B is a diagram illustrating the pressed air that flows downward from a part of the air that is reflected from the lower surface of the sheet within the transport guide plate. It is an enlarged view which shows the state which acts.

  A sheet conveying device 60 according to the fifth embodiment replaces the air reflecting plate 20 having the configuration of the sheet conveying device according to the first or second embodiment, and a pair of vertically arranged spaces as shown in FIG. Conveyance guide plates 61 and 61 (hereinafter simply referred to as “conveyance guide plate 61”) are provided. The conveyance guide plate 61 is a plate-like member provided on both side plate materials with a ventilation portion for air passage.

  As shown in FIG. 14, it is assumed that not only the uppermost sheet 1A but also the second and subsequent sheets are attracted to the electrostatic attraction belt 13A and conveyed in close contact without being separated from the air blowing section 14 with air A. In addition, a part of the air A from the air blowing unit 14 provided in the downstream conveyance unit of the electrostatic attraction belt 13A is reflected by the sheet (the lower surface of the uppermost sheet 1A in the illustrated example) and flows downward. As a result, only the uppermost sheet 1A is separated and conveyed.

  That is, as shown in FIG. 14B, before the sheet reaches the portion where the ventilation hole of the conveyance guide plate 61 is provided, the pushed-down air Ax passes through the ventilation hole of the conveyance guide plate 61, and the sheet is conveyed to the conveyance guide plate 61. When the sheet 61 enters between the plates 61 and reaches even a part of the vent hole, the sheet is deformed by air, and therefore, as shown in the figure, between the uppermost sheet 1A and a sheet (for example, the second sheet) in close contact therewith. Air enters, and this air is pushed down and air Ax enters, whereby the uppermost sheet 1A is separated from the two or more sheets that are in close contact with each other, and only the uppermost sheet 1A can be conveyed.

  Although the illustration of the air holes of the conveyance guide plate 61 is omitted, when the sheet does not reach the conveyance guide plate 61, the air A is allowed to pass through the air holes, and the air A is By acting as the push-down air Ax for the sheet reflected and adhered to the sheet, stable sheet conveyance and separation can be performed. As shown in FIG. 15A, the air hole 61a is configured to be a home base type slit shape (width 3 mm to 5 mm) closed on the downstream side of the sheet conveyance so that the sheet is not caught. Has been.

  Further, as shown in FIG. 15B, by providing a protrusion 61 b at a position where the sheet is in contact with the sheet of the conveyance guide plate 61, the sheet conveyed in close contact is deformed, and the sheet is in close contact with the uppermost sheet. By making the pushed-down air Ax easily enter between the two, stable sheet separation can be performed. The protrusion shape is a semicircular shape (R1 to R5), and does not damage the sheet. In this configuration, the protrusion shape is provided at one central upper portion, but the protrusion shape may be provided not only at the upper portion but also at the lower portion or at a plurality of locations.

  The sheet conveying apparatus according to the embodiment of the present invention described above can be used for improving sheet conveying operation in an image forming apparatus such as a digital copying machine, a printer, a facsimile machine, and an offset printing machine. It can be used by being mounted on a device or other similar devices.

  The present invention is not limited to the embodiments described above, and many modifications can be made by those having ordinary knowledge in the art within the technical idea of the present invention.

1: Sheet bundle 1A: Top sheet 10: Sheet conveying device 11: Sheet storage unit 12: Sheet lifting member 13: Electrostatic adsorption belt device 13A: Electrostatic adsorption belt 13B: Driving roller 13C: Driven roller 13D: Electrostatic adsorption belt Power supply device 13E: Electrostatic adsorption belt drive means 13F: Projection member 13G: Projection amount change means 14: Air blower 15A: Conveyance direction side edge regulating member 18: Sheet lifting member drive means 19: Control means 20: Reflector 21 : Electrode 21A: plus electrode 21B: minus electrode 22: insulating layer 23: transport center line 24A: driving force transmission mechanism 24B: driving force transmission mechanism 25: spline joint 25A: female spline 25B: male spline 27A, 27B: constant velocity joint 28: Drive gear 28A: Drive gear 28B: Rotation conduction device 61, 61: Transport guide plate 61a: Ventilation 61b: protrusion 100: copying machine (image forming apparatus)
110: Automatic document conveying device 120: Document reading unit 130: Paper feeding unit 131, 132: Electrostatic adsorption belt unit 140: Image forming unit 150: Paper feeding cassette 160: Sheet separation paper feeding device 170: Conveying path 180: Conveying roller Pair 190: Transfer roller 200: Fixing device 210: Paper discharge roller pair 220: Paper discharge tray 230: Image forming section (image forming section)
230Y, 230C, 230M, 230BK: image forming unit 240: intermediate transfer belt 250: exposure device 260: photoconductor 270: charging unit 280: developing unit 290: cleaning unit

JP 2007-45630 A

Claims (9)

A sheet storage section for storing the sheet bundle;
Sheet elevating means for elevating the sheet bundle vertically;
An adsorption belt device provided with a plurality of endless electrostatic adsorption belts that are positioned above the sheet bundle and electrostatically adsorb the uppermost sheet;
With
A gap is provided between the electrostatic adsorption belts of the adsorption belt device, and at least two adjacent electrostatic adsorption belts are arranged on the downstream side of the conveyance of the uppermost sheet from the interval on the upstream side of conveyance of the uppermost sheet. The sheet conveying apparatus is characterized by being arranged so as to have a large interval. At one end of the sheet bundle stored in the sheet storage unit,
Air is blown between at least two adjacent electrostatic adsorption belts of the plurality of electrostatic adsorption belts to float at least one end side of the uppermost sheet of the sheet bundle. The sheet conveying apparatus according to claim 1, further comprising an air blowing unit that separates the sheet bundle from the sheet bundle to a suckable state.   The sheet conveying apparatus according to claim 1, wherein the plurality of electrostatic adsorption belts are arranged symmetrically with respect to a conveyance center line of the conveyed sheet.   The arrangement positions of the plurality of electrostatic attraction belts are changed while maintaining the relationship in which the interval between the two adjacent electrostatic attraction belts is greater at the conveyance downstream end of the uppermost sheet than at the conveyance upstream end of the uppermost sheet. The sheet conveying apparatus according to any one of claims 1 to 3, further comprising a belt position changing unit that performs the operation.   A region where the air from the air blower can pass through the gap between the electrostatic adsorption belts in a state where the uppermost sheet is not lifted in the gap between the plurality of electrostatic adsorption belts Further, when the uppermost sheet levitated and floated from the adsorption surface of the electrostatic adsorption belt covers a gap between the electrostatic adsorption belts, the uppermost sheet is deformed, and the uppermost sheet and the uppermost sheet are next to the uppermost sheet. 5. The sheet conveying apparatus according to claim 2, further comprising at least one projecting member that forms a space in which air enters between the sheet and the sheet.   The sheet conveying apparatus according to claim 5, wherein the protruding member includes a rotating member that rotates as the uppermost sheet moves.   The sheet conveying apparatus according to claim 5, further comprising: a protruding amount changing unit that changes a protruding amount of the protruding member from the adsorption surface of the electrostatic adsorption belt.   The sheet conveying apparatus according to claim 2, further comprising an air amount changing device that changes an amount of air blown from the air blowing unit.   An image forming apparatus comprising: the sheet conveying apparatus according to claim 1; and an image forming unit that forms an image on a sheet from the sheet conveying apparatus.