JP2005231854A - Sheet conveyance device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet conveyance device having a suction conveyance mechanism capable of conveying a sheet by preventing unreasonable force from acting on the sheet even if a large clearance is formed between the first sheet and the second sheet and after. <P>SOLUTION: This sheet conveyance device 1 has a tray 2, a suction conveyance unit 3, a clearance forming means 4, and a conveyance prevention member 5. The suction conveyance unit 3 has a suction box 15 having a plurality of suction holes 15b on a face opposing to a sheet on the tray 2 and in a plane part 15a corresponding to a travel path of each endless belt 14 and a negative pressure generating means 16 for making pressure inside the suction box 15 negative pressure. A step part which is recessed in the direction in which it leaves the sheet 6 on the tray 2 more than each plane part 15a is provided in a section corresponding to a section between each endless belt 14 on the opposing face of the suction box 15, and a plurality of suction holes 15d are provided in the step part 15c. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sheet conveying apparatus having a suction conveying mechanism applicable to an image forming apparatus such as a stencil printing apparatus, an offset printing apparatus, an electrophotographic copying machine, and a printer.

  A pair of rollers disposed above a tray for stacking a large number of sheets, a belt having a plurality of air suction holes spanned between the rollers, and a space formed by the rollers and the belt. A housing having an air suction hole on the lower surface, and a pair of convex surfaces provided on the lower surface of the housing on the outer sides of both side edges of the belt and projecting downward from the belt conveying surface in the same direction as the belt running direction Projecting guides, a suction device that communicates with the casing and creates a negative pressure inside the casing, and a recess provided downstream of the downstream end of the sheet conveying direction in the conveying direction and inside each protruding guide. And a paper stopper that has a shape. The belt is moved by rotating each roller and the suction device is operated to suck the sheet on the tray to the belt. For example, Japanese Patent Application Laid-Open No. 2004-228867 discloses a sheet conveying apparatus having a suction conveying mechanism that stops a second and subsequent sheets that do not have a suction force when they are sucked by a paper stopper and conveys them while preventing double feeding. It is disclosed.

Japanese Patent No. 2827429

  In the above-described technique, when a plurality of sheets are sucked onto the belt, the second and subsequent sheets that do not have a suction force are difficult to follow the shape of the protruding guide due to the rigidity of the first sheet. The first sheet and the second and subsequent sheets are separated using a gap with the sheet, but if the protruding amount of the protruding guide is reduced, the first sheet and the second and subsequent sheets are separated. A sufficient gap cannot be formed between them, and the second and subsequent sheets are fed over the sheet stopper. In addition, when the upward curl is applied to the sheet and this degree is strong, the second and subsequent sheets are also fed over the sheet stopper.

  For this reason, if the protrusion amount of the protrusion guide is increased, the gap between the first sheet and the second and subsequent sheets is increased, and double feeding is eliminated. However, when the sheet is adsorbed to the belt, On the other hand, a large wave is likely to occur, and an unreasonable force is generated when the sheet conveyed downstream due to this wave enters a conveying member such as a conveying roller pair, which causes a conveyance jam or a wrinkle. .

  The present invention solves the above-described problems, and even if a large gap is formed between the first sheet and the second and subsequent sheets, the sheet is conveyed without excessive force acting on the sheet. This is possible, and even when it is difficult to form a gap between the first sheet and the second and subsequent sheets such as cardboard and envelopes, it is possible to prevent occurrence of double feeding and perform good conveyance. An object of the present invention is to provide a sheet conveying apparatus having a possible suction conveying mechanism.

  The invention according to claim 1 is a tray on which a large number of sheets are stacked, a suction conveyance unit that is provided above the tray and sucks and conveys one sheet from the sheet group on the tray, and a conveyance direction of the sheet group A gap forming means for forming a gap between the uppermost sheet and its lower sheet by blowing air to the downstream end surface, and the suction conveyance unit prevents the sheets other than the uppermost sheet from being conveyed. In the sheet conveying apparatus having a conveying blocking member, the suction conveying unit includes a pair of rotatable rollers, a plurality of endless belts spanned between the rollers at a predetermined interval, the rollers, A portion corresponding to a moving path of each of the endless belts is a facing surface provided in a space formed by each of the endless belts and facing a sheet on the tray. A suction box having a planar shape substantially parallel to the endless belt and having a plurality of suction holes in the flat portion, and negative pressure generating means for making the inside of the suction box negative, the facing surface of the suction box A portion corresponding to between the endless belts is formed in a concave shape so as to be farther from the sheet on the tray than the flat portions, and a plurality of suction holes are provided in the stepped portion.

  According to a second aspect of the present invention, in the sheet conveying apparatus according to the first aspect, the stepped portion is formed so as to be inclined in a direction away from the sheet on the tray as it goes from the upstream side to the downstream side in the sheet conveying direction. It is characterized by.

  According to a third aspect of the present invention, in the sheet conveying apparatus according to the first or second aspect, the plurality of suction holes provided in the stepped portion further increase from the upstream side to the downstream side in the sheet conveying direction. It is characterized in that the opening area is reduced.

  According to a fourth aspect of the present invention, in the sheet conveying apparatus according to any one of the first to third aspects, the gap forming means further includes a gap between the uppermost sheet and a lower sheet. It is characterized by moving from the lower side to the upper side while blowing out air to form.

  According to a fifth aspect of the present invention, in the sheet conveying apparatus according to any one of the first to fourth aspects, the conveyance blocking member is further in contact with and separated from the downstream end surface in the conveyance direction of the sheet group. The uppermost sheet and the lower sheet are separated when contacting the end face.

  According to a sixth aspect of the present invention, in the sheet conveying apparatus according to the fifth aspect, the conveyance preventing member further includes a contact portion that contacts the end face, and a separation portion that enters a gap between the uppermost sheet and a lower sheet thereof. It is characterized by having.

  A seventh aspect of the present invention is the sheet conveying apparatus according to the sixth aspect, wherein the separating portion is further inclined by 90 degrees or more from the contact portion toward the upstream side in the sheet conveying direction.

  According to an eighth aspect of the present invention, in the sheet conveying apparatus according to any one of the first to seventh aspects, the stepped portion further includes a plurality of steps substantially parallel to the sheet conveying direction around the suction hole. It has a ridge.

  According to the present invention, the gap forming means reliably forms a gap between the uppermost sheet and its lower sheet, and the conveyance blocking member is inserted into the formed gap, so that the uppermost sheet from the tray is Separation is ensured. Further, since the step portion is provided, the uppermost sheet adsorbed in the adsorption box has a natural wave shape, and a large gap can be formed between the uppermost sheet and the lower sheet.

  FIG. 1 shows a sheet conveying apparatus employing an embodiment of the present invention. This sheet conveying apparatus can be applied to a printing apparatus such as a stencil printing apparatus or an offset printing apparatus, and an image forming apparatus such as an electrophotographic copying machine or a printer.

  In FIG. 1, a sheet conveying apparatus 1 includes a tray 2, an adsorption conveying unit 3, a gap forming unit 4, a conveyance preventing member 5, and the like. On the downstream side of the sheet conveying apparatus 1 in the sheet conveying direction, a pair of guide plates 7 and 8 for guiding the conveyance of the sheet 6 fed by the sheet conveying apparatus 1 and the sheet 6 are printed at a predetermined timing or image formation. A registration roller pair 9 for feeding to the section is disposed. Reference numeral 10 denotes a jam detection sensor that detects whether or not the sheet 6 has been normally conveyed.

  A tray 2 on which a large number of sheets 6 are stacked is supported by an apparatus main body (not shown) so as to be movable up and down, and is raised and lowered by an elevator means (not shown). Above the sheets 6 stacked on the tray 2, a sheet position detection sensor 11 for detecting whether or not the uppermost sheet 6a positioned at the uppermost position on the tray 2 has risen to a predetermined position is disposed. When the sheet position detection sensor 11 detects the uppermost sheet 6a and outputs a signal, the operation of the lifting means (not shown) is stopped and the raising of the tray 2 is stopped. Note that the tray 2 is also raised by a predetermined amount when the sheet 6 is reduced during the image forming operation and the position of the uppermost sheet 6a is lowered.

  At the upper side of the tray 2 and on the downstream side in the conveyance direction of the sheets 6 stacked on the tray 2, an adsorption that conveys the uppermost sheet 6 a toward the registration roller pair 9 while adsorbing only one uppermost sheet 6 a from the tray 2. A transport unit 3 is provided. As shown in FIGS. 2 and 3, the suction conveyance unit 3 includes a driving roller 12, a driven roller 13, a plurality (two in this embodiment) endless belts 14 wound around the rollers 12, 13, A suction box 15 provided in a space formed by each of the rollers 12 and 13 and each endless belt 14, a suction fan 16 as a negative pressure generating means provided above the suction box 15, and the like.

  Two drive rollers 12 are attached to a drive shaft 12a rotatably supported by a bracket 17 provided in the suction box 15, and the drive shaft 12a is rotationally driven by a drive means (not shown), so that in FIG. It is driven to rotate in the clockwise direction. A one-way clutch (not shown) is incorporated between the drive shaft 12a and each drive roller 12, and the rotational force from the drive means (not shown) is transmitted to each drive roller 12, and the rotational force from each drive roller 12 is driven. The shaft 12a is configured not to be transmitted.

  Two driven rollers 13 are attached to a driven shaft 13 a that is rotatably supported by a bracket 18 provided in the suction box 15. An endless belt 14 having a plurality of holes 14a is wound between the rollers 12 and 13, respectively. With this configuration, the drive shaft 12a is driven to rotate so that the rollers 12 and 13 are respectively shown in FIG. By rotating in the clockwise direction, each endless belt 14 is moved in the direction indicated by the arrow in FIG.

  A suction box 15 having a casing shape is attached to the apparatus main body, and a suction fan 16 is attached to the upper part thereof. A bottom surface of the suction box 15, that is, a surface facing the sheet 6 on the tray 2 and corresponding to the moving path of each endless belt 14, forms a plane substantially parallel to each endless belt 14 stretched. Two flat portions 15a are formed, and a plurality of suction holes 15b are formed in each flat portion 15a.

  A stepped portion 15c that is recessed toward the upper side of the sheet 6 on the tray 2 rather than each flat portion 15a, that is, at a portion corresponding to the endless belt 14 on the bottom surface of the suction box 15, is provided. It has been. As shown well in FIG. 3, the step portion 15 c is formed so as to be inclined upward as it is away from the sheet 6 on the tray 2 toward the downstream side in the sheet conveying direction.

  A plurality of suction holes 15d are formed in the step portion 15c, and each suction hole 15d is formed such that the opening area thereof decreases from the upstream side to the downstream side in the sheet conveying direction. With this configuration, the suction hole 15d is formed over a wide range in the width direction of the sheet 6 as shown in FIG. 4 in the upstream portion in the sheet conveying direction, so that the uppermost sheet 6a has a high degree of adhesion to the step portion 15c. As shown in FIG. 5, the suction holes 15d are formed only sparsely in the downstream portion in the sheet conveyance direction, and the portion that is not sucked into the suction holes 15d of the uppermost sheet 6a has a gentle and natural wave shape. It is possible to form a large gap between the uppermost sheet 6a and its lower sheet 6 on the downstream side in the sheet conveying direction with a small suction force, and since the suction force is small, the uppermost sheet from the suction conveyance unit 3 can be formed. The sheet 6a can be easily separated.

  Beneath the suction conveyance unit 3 and in the vicinity of the downstream end of the sheet 6 group stacked on the tray 2 in the conveyance direction, air is blown toward the downstream end of the sheet 6 group in the conveyance direction. A gap forming means 4 for forming a gap between the sheet 6a and the sheet 6 positioned below the sheet 6a is disposed. As shown in FIGS. 6 and 7, the gap forming unit 4 includes a blower fan 19, an elbow member 20, and a swing nozzle 21.

  The blower fan 19 is attached to a mounting bracket 22 provided in the apparatus main body by a mounting screw 23, and an elbow member 20 is attached to the blower opening 19a. The elbow member 20 has a substantially fan shape so that the air blown from the air blowing port 19a is directed slightly downward. A locking piece 20a is integrally formed on the arcuate upper surface, and both outer side surfaces thereof. Each is provided with a protrusion 20b.

  A swing nozzle 21 is swingably attached to each protrusion 20b. The oscillating nozzle 21 having a cylindrical shape integrally includes an engaging portion 21a having an arcuate surface at a lower portion thereof, and an upper portion of the oscillating nozzle 21 has one end attached to the guide plate 7 (FIG. 9). The other end is attached.

  In this embodiment, as shown in FIG. 8, the gap forming means 4 is provided at three locations so that the air blowing ports 21 b of the swing nozzle 21 are located between the endless belts 14 and outside the endless belts 14, respectively. ing. Note that the gap forming means positioned on both outer sides of each endless belt 14 may be provided so as to be adjustable in the left-right direction in FIG. 8 according to the size in the width direction of the sheet 6 to be used. In each gap forming means 4, each swing nozzle 21 is integrally connected by a bracket (not shown), and is configured to be swingable integrally.

  A conveyance blocking member 5 is disposed between the downstream end portion in the conveyance direction of the group of sheets 6 stacked on the tray 2 and the gap forming unit 4 and substantially at the center in the width direction of the sheet 6. As shown in FIG. 9, the conveyance blocking member 5 having one end bent into a bowl shape to form two separation portions 5 a (see FIG. 8) is slightly closer to the other end than the end of the tray 2. The plate 2a is swingably supported. Near the one end of the conveyance blocking member 5, the other end of the tension spring 25 having one end fixed to the apparatus main body is attached, and the conveyance blocking member 5 is rotated in such a direction as to contact the other end with the end plate 2a. Energizing power is given. The bending angle θ of the separation unit 5a is set to about 90 to 110 degrees, and a contact unit 5b that is in contact with the downstream end surface in the conveyance direction of the group of sheets 6 is closer to the other end than the separation unit 5a. And is formed continuously.

  A swing arm 26 is disposed below the gap forming means 4 and the conveyance blocking member 5. The rod-like or plate-like swing arm 26 having one end 26a bent is supported by a bracket 27 attached to the end plate 2a so as to be swingable in the middle, and a cam follower 26b is rotatable at the other end. Is attached. In the vicinity of the cam follower 26b, a cam 28 having a large diameter portion 28a and a small diameter portion 28b, which is rotationally driven by a driving means (not shown) in synchronization with the paper feeding operation, is disposed. In addition, the other end of a tension spring 29 having one end fixed to the apparatus main body is attached in the vicinity of the other end of the swing arm 26, and the swing arm 26 is rotated in a direction in which the cam follower 26 b is brought into contact with the cam 28. A dynamic force is applied.

  The swing arm 26 is disposed at a substantially central portion in the width direction of the sheet 6, the tip of one end 26 a can contact the back surface of the conveyance blocking member 5, and the bent portion has a swing disposed at the center. A cylindrical or roller-like engaging member 26c that can be engaged with an engaging portion 21a provided only on the moving nozzle 21 is provided.

  Based on the above-described configuration, the operation of the sheet conveying apparatus 1 will be described below. When a start switch (not shown) is pressed, the raising / lowering means (not shown) is activated and the tray 2 starts to rise. Then, when the gap between the suction conveyance unit 3 and the uppermost sheet 6a reaches a predetermined interval, the sheet position detection sensor 11 detects the uppermost sheet 6a, the operation of the lifting means (not shown) is stopped, and the tray 2 is raised. Stops. When the raising of the tray 2 is stopped, the suction fan 16 and the blower fan 19 are operated at a predetermined timing, and the driving means (not shown) is operated to rotate the cam 28 in the clockwise direction in FIG.

  In the separated state in which the conveyance blocking member 5 is separated from the downstream end face in the conveyance direction of the group of sheets 6 on the tray 2 as shown in FIG. The air is gradually blown between the uppermost sheet 6a and the lower sheet 6 as shown in FIG.

  As the cam 28 rotates, as the contact position of the cam follower 26b with the cam 28 moves from the large-diameter portion 28a to the small-diameter portion 28b, the oscillating arm 26 moves clockwise in FIG. Start swinging. The engaging member 26c and the engaging portion 21a are kept engaged in the state before the swinging, and the swinging nozzle 21 has its blower port 21b at the uppermost seat 6a against the urging force of the tension spring 24. Located in the vicinity.

  When the swing arm 26 swings, the swing nozzle 21 having the engaging portion 21a engaged with the engaging member 26c swings counterclockwise around the protrusion 20b in FIG. 9 by the urging force of the tension spring 24. Then, the position of the air blowing port 21b moves from the lower side to the upper side. The air flow blown from the air blowing port 21b is also moved by the movement of the air blowing port 21b, and the number of sheets 6 remaining above the center line of the air flow blown to the end surface of the sheet 6 group gradually decreases. The gap formed by the air flow gradually increases from a portion far from the suction conveyance unit 3 (downward) to a portion near the top (upper), and the uppermost sheet 6a can be satisfactorily separated from the lower sheet 6. . Further, since the sheet 6 positioned on the lower side (tray 2 side) across the center line of the air flow is sequentially returned to the tray 2 side, the separation of the sheet 6 by the air flow is promoted.

  When the swinging of the swinging arm 26 advances and the engaging member 26c is separated from the engaging part 21a as shown in FIG. 10, the swinging nozzle 21 is swung by bringing its end into contact with the locking piece 20a. To stop. The swing stop position of the swing nozzle 21 is set to a position where the sheet 6 can be separated satisfactorily, and the swing angle of the swing nozzle 21 is set to about 5 to 10 degrees, for example.

  The separated uppermost sheet 6a receives the action of the suction fan 16 when the hole portion 14a and the suction hole 15b overlap with each other, and is adsorbed to each endless belt 14. In the step portion 15c, the sheet 6 is attracted upward by the action of the suction fan 16 through the suction hole 15d. At this time, as shown in FIG. 4 on the upstream side in the sheet conveyance direction, the uppermost sheet 6a is adsorbed to the step portion 15c as shown in FIG. 5 on the downstream side in the sheet conveyance direction, and the above-described good effects are exerted.

  When the swinging arm 26 further swings and the transport blocking member 5 is swung by pushing the transport blocking member 5 by the one end 26a as shown in FIG. 11, the separating portion 5a is separated from the uppermost sheet 6a. The contact portion 5b comes into contact with the end surface of the group of sheets 6 while entering between the lower sheets 6. At this time, at the boundary between the separation portion 5a and the contact portion 5b, the sheet 6 that floats upward is returned downward, and the contact portion 5b contacts the end surface of the sheet 6, so that the sheet 6 can be separated in an orderly manner. it can.

  The separated uppermost sheet 6a is conveyed to the registration roller pair 9 by the suction conveyance unit 3, and is used for image formation when the registration roller pair 9 operates at a predetermined timing.

  With the above-described configuration, the gap forming unit 4 reliably forms a gap between the uppermost sheet 6a and the lower sheet 6 and the conveyance blocking member 5 is inserted into the formed gap. 2 is surely separated from the uppermost sheet 6a from above. Further, since the step portion 15c is provided, the uppermost sheet 6a adsorbed to the adsorption box 15 has a natural wave shape, and a large gap is formed between the uppermost sheet 6a and the lower sheet 6. be able to.

  As a modification of the above embodiment, a conveyance blocking member 30 shown in FIG. 12 may be used instead of the conveyance blocking member 5. The conveyance blocking member 30 includes a first member 30A in which a contact portion 30b is formed, and a second member 30B in which two separation portions 30a and two contact portions 30c are formed. Long holes 30d are formed in the first member 30A at two locations, and the second member 30B is attached to the first member 30A so that the position of the second member 30B can be adjusted in the vertical direction by a set screw 31 that engages with the long holes 30c.

  By using this conveyance blocking member 30, the relative position between the first member 30A and the second member 30B is adjusted when the gap formed between the uppermost sheet 6a and the lower sheet 6 is small. Thus, the separation part 30a can be made to correspond to the gap. In addition, when adjusting the relative position of the first member 30A and the second member 30B, the contact portions 30b and 30c are provided so that the positions in the height direction surely wrap. Thereby, the front-end | tip of the sheet | seat 6 can be made to contact any one of contact parts 30b and 30c reliably, and the consistency of the sheet | seat 6 can be hold | maintained.

  In the embodiment and the modification, a plurality of circular suction holes 15d are provided in the step portion 15c, and the suction holes 15d are arranged so that the opening area decreases from the upstream side to the downstream side in the sheet conveyance direction. However, instead of each suction hole 15d, as shown in FIG. 13, a plurality of elongated suction holes 15e having different opening areas are formed, and the suction holes 15e are opened from the upstream side to the downstream side in the sheet conveying direction. It is good also as a structure arrange | positioned so that a hole area may reduce. With this configuration, the same effects as those of the above embodiment can be obtained.

  As another modification of the above embodiment and modification, as shown in FIGS. 14 and 15, a plurality of protrusions 32 formed in the same direction as the sheet conveying direction are provided in the vicinity of the suction holes 15d and 15e. It is good. With this configuration, it is possible to reduce the frictional resistance against the step portion 15c of the sheet 6 during conveyance, and it is possible to perform good sheet conveyance. The height of each protrusion 32 has been experimentally determined from the magnitude of the negative pressure generated by the suction fan 16 and the physical property values (for example, the coefficient of friction) relating to the sheet conveyance of each endless belt 14, and is 0.2 in this embodiment. If it is about -0.7 mm, the sheet can be conveyed in a state where there is almost no slip between each endless belt 14 and the sheet 6 while minimizing the loss of suction. Of course, the height of each protrusion 32 differs depending on the magnitude of the negative pressure and the physical property value.

  Further, as can be seen from FIG. 1, the positions of the driving roller 12, the tray 2, the registration roller pair 9 and the like can be configured in the same manner as a conventional sheet conveying apparatus having a sheet feeding roller and a separation pad. It is also possible to divert the drive unit to a suction conveyance type sheet conveying apparatus relatively easily with a minimum design change compared to the conventional machine.

1 is a schematic front view of a sheet conveying apparatus adopting an embodiment of the present invention. It is a schematic bottom view of the adsorption conveyance unit used for one Embodiment of this invention. It is a partial front view of the adsorption conveyance unit used for one Embodiment of this invention. FIG. 5 is a schematic diagram for explaining the behavior of a sheet with respect to a step portion on the upstream side in the sheet conveying direction according to an embodiment of the present invention. FIG. 6 is a schematic diagram for explaining the behavior of a sheet with respect to a step portion on the downstream side in the sheet conveyance direction in an embodiment of the present invention. It is a schematic front view of the clearance gap formation means used for one Embodiment of this invention. It is a schematic plan view of the clearance gap formation means used for one Embodiment of this invention. It is the schematic which shows the positional relationship of the adsorption conveyance unit used for one Embodiment of this invention, each clearance gap formation means, and a conveyance prevention member. It is the schematic for demonstrating the clearance gap formation means and conveyance prevention member in the conveyance initial stage in one Embodiment of this invention. It is the schematic for demonstrating the clearance gap formation means and conveyance prevention member in the conveyance middle stage in one Embodiment of this invention. It is the schematic for demonstrating the clearance gap formation means and conveyance prevention member in the conveyance latter stage in one Embodiment of this invention. It is the schematic which shows the conveyance prevention member used for the modification of one Embodiment of this invention. It is the schematic which shows the suction hole used for the other modification of one Embodiment of this invention. It is the schematic which shows the protrusion used for the other modification of one Embodiment of this invention. It is the schematic which shows the protrusion used for the other modification of one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sheet conveyance apparatus 2 Tray 3 Adsorption conveyance unit 4 Gap formation means 5,30 Conveyance prevention member 5a, 30a Separation part 5b, 30b, 30c Contact part 6 Sheet 6a Topmost sheet 12 Drive roller 13 Driven roller 14 Endless belt 15 Adsorption box 15a Plane portion 15b Suction hole 15c Stepped portion 15d Suction hole 16 Negative pressure generating means (suction fan)
32 ridges

Claims (8)

A tray on which a large number of sheets are stacked, a suction conveyance unit that is provided above the tray and sucks and conveys one sheet from the sheet group on the tray, and air is blown to the downstream end surface in the conveyance direction of the sheet group Sheet conveying means having a gap forming means for forming a gap between the uppermost sheet and its lower sheet, and a conveyance blocking member for inhibiting conveyance of a sheet other than the uppermost sheet by the suction conveyance unit. In the device
The suction conveyance unit includes a pair of rotatable rollers, a plurality of endless belts spanned between the rollers at a predetermined interval, and a space formed by the rollers and the endless belts. A suction surface that is provided and faces the sheet on the tray and that corresponds to the moving path of each endless belt is substantially parallel to each endless belt and has a plurality of suction holes in the flat portion. A negative pressure generating means for making a negative pressure inside the box and the suction box,
A portion corresponding to the endless belts on the facing surface of the suction box is recessed in a direction away from the sheet on the tray rather than the flat portions, and a plurality of suction holes are provided in the stepped portion. A sheet conveying apparatus. The sheet conveying apparatus according to claim 1,
The sheet conveying apparatus, wherein the stepped portion is formed to be inclined in a direction away from the sheet on the tray as it goes from the upstream side to the downstream side in the sheet conveying direction. In the sheet conveying apparatus according to claim 1 or 2,
The plurality of suction holes provided in the stepped portion are formed so that the aperture area decreases from the upstream side to the downstream side in the sheet conveying direction. In the sheet conveying apparatus according to any one of claims 1 to 3,
The sheet conveying device, wherein the gap forming means moves from below to above while blowing air to form a gap between the uppermost sheet and a lower sheet. In the sheet conveying apparatus according to any one of claims 1 to 4,
The sheet is characterized in that the conveyance blocking member is freely contactable and separable with respect to the downstream end surface in the conveyance direction of the sheet group, and separates the uppermost sheet and its lower sheet when abutting against the end surface. Conveying device. In the sheet conveying apparatus according to claim 5,
The sheet conveyance device, wherein the conveyance blocking member includes a contact portion that contacts the end surface and a separation portion that enters a gap between the uppermost sheet and a lower sheet. The sheet conveying apparatus according to claim 6,
The sheet conveying apparatus, wherein the separation unit is inclined by 90 degrees or more from the contact portion toward the upstream side in the sheet conveying direction. In the sheet conveying apparatus according to any one of claims 1 to 7,
The sheet conveying apparatus according to claim 1, wherein the step portion has a plurality of protrusions substantially parallel to the sheet conveying direction around the suction hole.

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