Blowing device and sheet conveying system
By using an air blowing device in the sheet conveying system to blow air into the overlapping areas between sheets, the problems of wear, scratches, contamination and static electricity caused by sliding friction during high-speed conveying are solved, improving system stability and product quality. .
Patent Information
- Application Number
- CN202421097243.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-20
- Publication Date
- 2025-01-21
- Estimated Expiration
- 2034-05-20
AI Technical Summary
In the sheet conveying system, partially overlapping sheets are prone to sliding friction during high-speed conveying, resulting in wear, scratches, pollution and static problems, increasing waste rate and system instability.
Design an air blowing device that senses the movement of the pickup component through a sensor, controls the valve device to open and close the gas channel, and uses the air blowing pipe to blow air into the overlapping area between the sheets to form an air cushion layer to avoid sliding friction.
It effectively avoids sliding friction between sheets, reduces wear, scratches, contamination and static electricity problems, and improves the stability and product quality of the sheet conveying system.
Smart Images
Figure CN222373898U_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to an air blowing device and a sheet material conveying system including the air blowing device. Background Art
[0002] In a conveying system for conveying sheets such as offset paper, coated paper, and white cardboard, a plurality of sheets are generally fed stacked together, and problems easily occur when the stacked plurality of sheets are separated one by one and conveyed at high speed.
[0003] Refer to the following Figure 6 and Figure 7 The general configuration of a sheet material conveying system of the related art is described.
[0004] The sheet conveying system of the prior art includes a sheet feeding device 20, a sheet conveying platform 30, and a sheet conveying device 40. The sheet feeding device 20 feeds a plurality of sheets to the sheet conveying platform 30. The fed plurality of sheets are conveyed on the sheet conveying platform 30 in a partially overlapping manner along a conveying direction X. A suction device (not shown) that generates a certain negative pressure is provided below the sheet conveying platform 30, so that the sheets are kept on the sheet conveying platform 30 while being conveyed and do not fall off, thereby making the conveyance of the sheets on the sheet conveying platform 30 stable.
[0005] exist Figure 7 Schematically shows three consecutive sheets S1, S2, S3. Figure 7 As shown, in the conveying direction X, the rear end S1b of the sheet S1 at the front is located above the following sheet S2, and the front end S2a of the sheet S2 is located below the sheet S1, so that there is an overlapping area SO between the front end S2a of the sheet S2 and the rear end S1b of the sheet S1. Similarly, the rear end S2b of the sheet S2 is located above the following sheet S3, and the front end S3a of the sheet S3 is located below the sheet S2, so that there is an overlapping area between the front end S3a of the sheet S3 and the rear end S2b of the sheet S2.
[0006] The sheet conveying device 40 is used to convey the multiple sheets stacked on the sheet conveying platform 30 one by one to the downstream post-processing device. The sheet conveying device 40 includes a picking member 41 and a conveying roller 42. The picking member 41 can quickly pick up a sheet to the conveying roller 42, and the picked sheet is conveyed downstream by the conveying roller 42. Generally, the picking member 41 is in the form of a swinging tooth. Figure 7 The central axis 44 swings back and forth along the R direction. Figure 7 When swinging counterclockwise, the pickup member 41 swings from the pickup position to the conveying position to pick up the sheet S1 to the conveying roller 42. After the sheet S1 reaches the conveying roller 42 and is conveyed by the conveying roller 42, the pickup member 41 swings clockwise and returns to the pickup position to prepare to pick up the next sheet S2.
[0007] The following describes the conveying process of the sheets in the sheet conveying system by taking the sheets S1 and S2 as examples.
[0008] Sheets S1 and S2 are fed by the sheet feeding device 20 and are conveyed on the sheet conveying platform 30 at a speed V1 in a partially overlapping manner along the conveying direction X until the sheet S1 reaches the sheet alignment device (not shown) of the sheet conveying device 40. The speed of the sheet S1 is reduced to a speed V2 close to zero at the sheet alignment device, and the deflection is corrected by the sheet alignment device to ensure that the front end of the sheet S1 is perpendicular to the conveying direction X on the plane of the sheet conveying platform 30. Then the sheet S1 is picked up by the picking member 41 and conveyed to the conveying roller 42 by the picking member 41 at a speed V3, V3>V1. At this time, the latter sheet S2 is still conveyed on the sheet conveying platform 30 at a speed V1. Due to the speed difference between V3 and V1, sliding friction is easily generated at the overlapping area S0 between the sheet S1 and the sheet S2, resulting in wear, scratches and contamination of the sheets S1 and S2, which increases the scrap rate of the product. In addition, sliding friction easily generates static electricity during the conveying process, causing the sheets to be adsorbed to each other or to the sheet conveying platform 30, thereby causing the sheets to wrinkle or become blocked. Utility Model Content
[0009] In order to overcome at least one of the above defects, according to a first aspect of the present disclosure, a blowing device is provided, in a sheet conveying system for conveying sheets, the sheet conveying system comprising a sheet feeding device, a sheet conveying platform for conveying sheets along a sheet conveying direction, and a sheet conveying device, the sheet conveying device comprising a picking member and a conveying roller configured to pick up the sheet, the picking member being able to move back and forth between a first position for picking up the sheet and a second position for conveying the sheet to the conveying roller, characterized in that the blowing device comprises: a bracket, the bracket being provided with a gas passage inside; a valve device, the valve device being mounted on the bracket and being provided with a gas passage inside, the valve device being configured to open the gas passage of the valve device when turned on a gas passage of the support, the gas passage of the valve device and closing the gas passage of the valve device when disconnected; an air blowing pipe, the air blowing pipe comprising an air inlet end and an air outlet end, and being provided with a gas passage inside, wherein when the valve device is connected, the gas passage of the support, the gas passage of the valve device and the gas passage of the air blowing pipe are connected to each other; a processor, wherein the processor is configured to control the connection and disconnection of the valve device; a sensor, wherein the sensor is installed in the sheet conveying device and is configured to sense the movement of the picking member, wherein when the picking member is in the first position, the sensor sends a signal to the processor to connect the valve device, and when the picking member is in the second position, the sensor sends a signal to the processor to disconnect the valve device.
[0010] Preferably, the bracket is a first bracket, the air blowing device further comprises a second bracket, the second bracket is fixed to the sheet conveying device, and the first bracket is configured to be able to slide back and forth on the second bracket in a sheet conveying direction.
[0011] Preferably, the valve device comprises a regulating valve, and the regulating valve is capable of adjusting the cross-sectional size of the gas channel of the valve device.
[0012] Preferably, the valve device is provided with a sliding structure, and can slide back and forth on the bracket in a direction perpendicular to the sheet conveying direction through the sliding structure.
[0013] Preferably, the blowing pipe is configured to be able to change shape and stabilize, thereby changing the position of the air outlet end of the blowing pipe and the angle of the blowing relative to the surface of the sheet.
[0014] Preferably, the valve device and the air blowing pipe are both provided in plurality, and each air blowing pipe is connected to a corresponding valve device at the air inlet end.
[0015] Preferably, only one valve device is provided, and a plurality of air blowing pipes are provided.
[0016] Preferably, the blowing device is also provided with a connecting pipe and a joint, the connecting pipe connects the joint and the valve device, the joint is installed on the bracket, the connecting pipe and the joint are both provided with gas channels inside, and when the valve device is connected, the gas channel of the bracket, the gas channel of the connecting pipe, the gas channel of the joint, the gas channel of the valve device and the gas channel of the blowing pipe are interconnected.
[0017] Preferably, the sensor is a proximity switch.
[0018] According to another aspect of the present disclosure, a sheet conveying system is also provided, which includes: a sheet feeding device; a sheet conveying platform for conveying sheets along a sheet conveying direction, the sheet feeding device conveys the sheets to the sheet conveying platform; a sheet conveying device, the sheet conveying device including a picking member and a conveying roller configured to pick up the sheets, the picking member being able to move back and forth between a first position for picking up the sheets and a second position for conveying the sheets to the conveying roller; and an air blowing device according to the first aspect of the present disclosure, the air blowing device being arranged upstream of the sheet conveying device in the sheet conveying direction. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Aspects of the present disclosure will be better understood after reading the following detailed description in conjunction with the accompanying drawings, in which:
[0020] Figure 1 is a diagram schematically showing a sheet conveying system according to an embodiment of the present disclosure;
[0021] Figure 2 is a perspective view schematically showing a sheet conveying system according to an embodiment of the present disclosure;
[0022] Figure 3 is a partial cross-sectional view schematically showing a sheet conveying system according to an embodiment of the present disclosure, wherein an air blowing device is omitted;
[0023] Figure 4 is a top view schematically showing an air blowing device according to an embodiment of the present disclosure;
[0024] Figure 5A and 5B is a diagram schematically showing a pickup member and a sensor of a sheet conveying system according to an embodiment of the present disclosure;
[0025] Figure 6 is a diagram schematically showing a sheet conveying system of the prior art;
[0026] Figure 7 is a partial cross-sectional view schematically showing a sheet conveying system of the related art. DETAILED DESCRIPTION
[0027] The present disclosure will be described below with reference to the accompanying drawings, wherein the accompanying drawings illustrate several embodiments of the present disclosure. However, it should be understood that the present disclosure can be presented in a variety of different ways and is not limited to the embodiments described below; in fact, the embodiments described below are intended to make the disclosure of the present disclosure more complete and fully illustrate the scope of protection of the present disclosure to those skilled in the art. It should also be understood that the embodiments disclosed herein can be combined in various ways to provide more additional embodiments. In addition, the drawings only schematically illustrate the embodiments and are not necessarily drawn to scale.
[0028] It should be understood that in all the drawings, the same reference numerals represent the same elements. The terms in the specification are only used to describe specific embodiments and are not intended to limit the present disclosure. All terms (including technical terms and scientific terms) used in the specification have the meanings commonly understood by those skilled in the art unless otherwise defined. For the sake of simplicity and / or clarity, well-known functions or structures may not be described in detail.
[0029] Refer to the following Figures 1 to 4 A sheet conveying system and an air blowing device according to an embodiment of the present disclosure are described.
[0030] The sheet conveying system according to the embodiment of the present disclosure includes an air blowing device 100, a sheet feeding device 200, a sheet conveying platform 300, and a sheet conveying device 400. The sheet feeding device 200 feeds a plurality of sheets to the sheet conveying platform 300. The fed plurality of sheets are conveyed on the sheet conveying platform 300 in a partially overlapping manner along a conveying direction X. A suction device (not shown) that generates a certain negative pressure is provided below the sheet conveying platform 300, so that the sheets are kept on the sheet conveying platform 300 while being conveyed and do not fall off, thereby making the conveying of the sheets on the sheet conveying platform 300 stable.
[0031] The sheet conveying device 400 is used to convey the multiple sheets stacked on the sheet conveying platform 300 one by one to the downstream post-processing device. The sheet conveying device 400 includes a picking member 401 and a conveying roller 402. The picking member 401 can quickly pick up a sheet to the conveying roller 402, and the picked sheet is conveyed downstream by the conveying roller 402. Usually, the picking member 401 is in the form of a swinging tooth. Figure 3 The arm 403 integrated with the pickup member 401 also swings back and forth in the R direction around the axis 404. Figure 3 When swinging counterclockwise, the pickup member 401 swings from the pickup position to the conveying position to pick up the sheet S1 to the conveying roller 402. After the sheet S1 reaches the conveying roller 42 and is conveyed by the conveying roller 402, the pickup member 401 swings clockwise and returns to the pickup position to prepare to pick up the next sheet S2.
[0032] The air blowing device 100 includes an air blowing device body 101, a sensor 102, and a processor (not shown). Figure 2 As shown, the air blowing device body 101 is disposed upstream of the sheet conveying device 400 in the sheet conveying direction X, and is close to the sheet conveying device 400. Figure 3 As shown, the sensor 102 is fixedly disposed in the sheet conveying device 400 .
[0033] like Figure 2 and Figure 4 As shown, the blowing device body 101 includes a first bracket 1, a second bracket 2, a third bracket 3, a valve device 4, a blowing pipe 5, a connecting pipe 6 and a joint 7. The first bracket 1 is hollow and connected to an air source AS, so that air can flow from the air source AS into the first bracket 1. The first bracket 1 is fixed to the second bracket 2 or is integrated with the first bracket 2, and the second bracket 2 has a concave groove, is mounted on the third bracket 3 and can slide back and forth along the third bracket 3 in the conveying direction X. The third bracket 3 is fixed to the sheet conveying device 400, extends in a direction opposite to the conveying direction X, and is separated from the sheet conveying platform 300 by a certain distance in the height direction so as not to interfere with the sheet being conveyed. Figure 2 and Figure 4 In the embodiment, the second bracket 2 and the third bracket 3 are arranged in pairs, but there is no specific limitation on their number.
[0034] The valve device 4 and the joint 7 are mounted on the first bracket 1. One end of the connecting pipe 6 is connected to the joint 7, and the other end is connected to the valve device 4. One end (the air inlet end) of the air blowing pipe 5 is connected to the valve device 4, and the other end (the air outlet end) can move freely. The valve device 4, the air blowing pipe 5, the connecting pipe 6 and the joint 7 are all provided with gas channels inside, so that the gas can flow from the gas source AS to the air blowing pipe 5 via the first bracket 1, the joint 7, the connecting pipe 6, the valve device 4, and be blown out from the air blowing pipe 5.
[0035] exist Figure 2 and Figure 4 In the figure, two and three groups of valve devices 4, air blowing pipes 5, connecting pipes 6 and joints 7 are respectively shown. However, it should be understood that the number of groups of valve devices 4, air blowing pipes 5, connecting pipes 6 and joints 7 is not limited to those shown in the figure, but more or less groups can be provided according to actual needs.
[0036] The valve device 4 can receive a signal from the controller and be turned on or off, thereby controlling the opening and closing of the gas channel in the valve device 4. The valve device 4 may include a solenoid valve, for example. Optionally, the valve device 4 may also include a regulating valve to adjust the cross-sectional size of the gas channel, thereby changing the gas volume and pressure passing through the gas channel as required (for example, according to the type and thickness of the sheet material, etc.).
[0037] Optionally, the valve device 4 may be provided with a sliding structure that cooperates with the first bracket 1, so that the valve device 4 can be moved on the first bracket 1 along a direction perpendicular to the conveying direction X ( Figure 4 The air inlet end of the air pipe 5 can be adjusted to the desired position by sliding back and forth in the left and right directions.
[0038] Optionally, the air blowing pipe 5 is an adjustable pipe. The operator can change the shape of the air blowing pipe 5 and the position of the air outlet end and stabilize it as needed, thereby adjusting the angle and position of the air blowing relative to the sheet surface. Preferably, the angle of the air blowing relative to the sheet surface is 15 to 30 degrees. The air blowing pipe 5 with a stable shape will not change its shape due to its internal air pressure, and maintains its shape stable and unchanged without the action of external force, so that the position of the air outlet end is stable and unchanged. Preferably, the air blowing pipe 5 has a universal structure.
[0039] The sensor 102 is fixedly arranged near the arm 403 and can sense the movement of the arm 403. Figure 5B When the pick-up member 401 is in the conveying position ( Figure 5AWhen the arm 403 is in position P1 in the middle, the arm 403 is in a position away from the sensor 102, and the sensor 102 sends a signal to the controller for disconnecting the valve device 4. Preferably, the sensor is a proximity switch.
[0040] After receiving the corresponding signal from the sensor 102, the controller (not shown) sends an on or off instruction to the valve device 4, thereby opening or closing the air passage.
[0041] The working process of the sheet conveying system and the air blowing device of this embodiment will be described below by taking sheets S1 and S2 as examples.
[0042] The sheets S1 and S2 are fed by the sheet feeding device 200 and are conveyed on the sheet conveying platform 300 at a speed V1 in a partially overlapping manner along the conveying direction X until the sheet S1 reaches the sheet alignment device (not shown) of the sheet conveying device 400. The speed of the sheet S1 is reduced to a speed V2 close to zero at the sheet alignment device, and the sheet alignment device corrects the deflection to ensure that the front end of the sheet S1 is perpendicular to the conveying direction X on the plane of the sheet conveying platform 300. Then the sheet S1 is picked up by the picking member 401 and conveyed by the picking member 401 at a speed V3, V3>V1. When the picking member 401 is in the picking position ( Figure 5B When the sheet S1 is in position P2), the arm 403 is in a position close to the sensor 102, and the sensor 102 sends a signal to the controller for connecting the valve device 4. The controller controls the valve device 4 to be in the connected state, and the gas channel is opened. The air flows from the gas source AS to the blowing pipe 5 via the first bracket 1, the joint 7, the connecting pipe 6, and the valve device 4, and is blown out from the blowing pipe 5 to the overlapping area SO between the sheets S1 and S2, so that the rear part of the sheet S1 is separated from the front part of the sheet S2 and an air cushion layer is formed therebetween, so that when the sheet S1 is picked up by the picking member 401 and conveyed to the conveying roller 402, no sliding friction occurs between the sheet S1 and the sheet S2, thereby avoiding the occurrence of wear, scratches, pollution and static electricity.
[0043] When the picking member 401 swings from the picking position to the conveying position ( Figure 5A When the sheet S1 is in position P1 in the drawing, the arm 403 is in a position away from the sensor 102, and the sensor 102 sends a signal to the controller for disconnecting the valve device 4, and the controller controls the valve device 4 to be in a disconnected state, and the gas passage is closed. Therefore, in the time period from when the sheet S1 is conveyed to the conveying roller 402 to when the picking member 401 returns to the picking position, the blowing device 100 does not blow air to the sheet until the moment when the picking member 401 is in the picking position (at this time, the sheet S2 is synchronously waiting to be picked up by the picking member 401 after being corrected for deflection by the sheet alignment device), the sensor 102 sends a signal to the controller for connecting the valve device 4, and then the controller opens the valve device 4 again, so that the blowing device 100 blows air to the overlapping area between the sheet S2 and the sheet S3.
[0044] By using the air blowing device 100 of the present disclosure, air is blown toward the overlapping area between the sheets during the conveyance of a plurality of partially overlapped sheets, thereby avoiding sliding friction between the sheets and further avoiding various defects caused by the sliding friction.
[0045] In addition, the blowing device 100 of the present disclosure senses the movement of the picking member or the member integrated with the picking member by setting a sensor, so that the blowing device intermittently blows air to the sheet. It is conceivable that the blowing device can blow air to the sheet continuously, but this is easy to blow the sheet crooked, and the continuously blown gas may press the upper sheet onto the rear sheet and it is not easy to separate the overlapping area of the sheet. The blowing device of the present disclosure adopts intermittent blowing, and only blows air when the front sheet is picked up by the picking member, which can avoid the above problems caused by continuous blowing.
[0046] Furthermore, the air blowing device 100 of the present disclosure can be conveniently installed on an existing sheet material conveying system and is easy to use.
[0047] An embodiment of the present disclosure is described above, but it should be understood that the present disclosure is not limited thereto. A person skilled in the art may conceive of various modifications without departing from the scope of the present disclosure.
[0048] For example, in the above-described embodiment, two or three groups of valve devices 4, air blowing pipes 5, connecting pipes 6 and joints 7 are provided, and each valve device 4 controls the corresponding air blowing pipe 5. However, it is conceivable that only one valve device 4 is provided to control all the air blowing pipes 5. This saves the number of valve devices 4 and reduces the cost. In the embodiment of the present disclosure, a valve device 4 is provided for each air blowing pipe 5, so that each air blowing pipe 5 can be flexibly and independently controlled to blow air. One advantage of this is that the moisture content of different parts of the sheet can be adjusted.
[0049] For example, in the above-described embodiment, the connecting pipe 6 and the joint 7 are provided, but they are not essential. It is conceivable that the connecting pipe 6 and the joint 7 are omitted, and the gas passage in the valve device 4 is connected to the gas passage of the first bracket 1 so that the gas flows from the first bracket 1 to the blowing pipe 5.
[0050] For example, in the above-described embodiment, a first bracket 1, a second bracket 2, and a third bracket 3 are provided, however, this is not necessary. It is conceivable that only one fixed bracket is provided to mount the valve device 4 and the vent pipe 5. In the embodiment of the present disclosure, a plurality of brackets are provided, so that the first bracket 1 on which the valve device 4 and the vent pipe 5 are mounted can move forward and backward, thereby improving the flexibility of the arrangement and the adjustability of the blowing position.
[0051] For example, in the above-described embodiment, the sensor 102 is disposed downstream of the pickup member 401 in the sheet conveying direction ( Figure 5A , 5B The sensor 102 may be positioned upstream of the pick-up member 401 (i.e., to the left of the pick-up member 401) to sense the movement of the arm 403, however this is not required. Figure 5A , 5B The position of the right side of the picking member 401 in the middle is used to sense the movement of the picking member 401. In this case, when the picking member 401 is in the picking position ( Figure 5B When the picking member 401 is in the conveying position ( Figure 5A When the pick-up member 401 is at position P1), the pick-up member 401 is at a position away from the sensor, and the sensor sends a signal to the controller for disconnecting the valve device 4. Therefore, the position of the sensor 102 is not specifically limited as long as it can sense the movement of the pick-up member or its integral member.
[0052] For example, in the embodiment described above, the sensor 102 is a proximity switch, however this is not required. It is contemplated that the sensor may be an optical sensor, a magnetic sensor, or the like.
[0053] It should be understood by those skilled in the art that various changes and modifications can be made to the exemplary embodiments of the present disclosure without departing from the spirit and scope of the present disclosure in essence. Therefore, all changes and modifications are included in the scope of protection of the present disclosure as defined by the claims. The present disclosure is defined by the attached claims, and the equivalents of these claims are also included.
Claims
1. An air blowing device, used in a sheet conveying system for conveying sheets, the sheet conveying system comprising a sheet feeding device, a sheet conveying platform for conveying sheets along a sheet conveying direction, and a sheet conveying device, the sheet conveying device comprising a picking member and a conveying roller configured to pick up the sheet, the picking member being able to move back and forth between a first position for picking up the sheet and a second position for conveying the sheet to the conveying roller, characterized in that The blowing device comprises: A support having a gas passage therein; a valve device, the valve device being mounted on the bracket and having a gas passage therein, the valve device being configured to open the gas passage of the valve device when connected and to close the gas passage of the valve device when disconnected; An air blowing pipe, the air blowing pipe comprises an air inlet end and an air outlet end, and is provided with an air passage inside, and when the valve device is connected, the air passage of the bracket, the air passage of the valve device and the air passage of the air blowing pipe are interconnected; A processor, the processor being configured to control the switching on and off of the valve device; A sensor is installed in the sheet conveying device and is configured to sense the movement of the picking member. When the picking member is in the first position, the sensor sends a signal to the processor to connect the valve device, and when the picking member is in the second position, the sensor sends a signal to the processor to disconnect the valve device.
2. The blowing device according to claim 1, characterized in that: The bracket is a first bracket, the air blowing device further includes a second bracket, the second bracket is fixed to the sheet conveying device, and the first bracket is configured to be able to slide back and forth on the second bracket in a sheet conveying direction.
3. The blowing device according to claim 1, characterized in that: The valve device comprises a regulating valve, which is capable of adjusting the cross-sectional size of a gas passage of the valve device.
4. The blowing device according to claim 1, characterized in that: The valve device is provided with a sliding structure, and can slide back and forth on the bracket in a direction perpendicular to the sheet conveying direction by the sliding structure.
5. The blowing device according to claim 1, characterized in that: The air blowing pipe is configured to be able to change shape and stabilize, thereby changing the position of the air outlet end of the air blowing pipe and the angle and position of the air blowing relative to the surface of the sheet.
6. The blowing device according to claim 1, characterized in that: The valve device and the air blowing pipe are both provided in plurality, and each air blowing pipe is connected to a corresponding valve device at the air inlet end.
7. The blowing device according to claim 1, characterized in that: The valve device is only provided with one, while the air blowing pipe is provided with a plurality.
8. The blowing device according to claim 1, characterized in that: A connecting pipe and a joint are also provided, wherein the connecting pipe connects the joint and the valve device, and the joint is installed on the bracket. The connecting pipe and the joint are both provided with gas channels inside. When the valve device is connected, the gas channel of the bracket, the gas channel of the connecting pipe, the gas channel of the joint, the gas channel of the valve device and the gas channel of the blowing pipe are interconnected.
9. The blowing device according to claim 1, characterized in that: The sensor includes a proximity switch.
10. A sheet material conveying system, comprising: Sheet feeding device; a sheet conveying platform for conveying sheets along a sheet conveying direction, wherein the sheet feeding device conveys the sheets to the sheet conveying platform; a sheet conveying device including a pick-up member configured to pick up a sheet and a conveying roller, the pick-up member being movable back and forth between a first position for picking up the sheet and a second position for conveying the sheet to the conveying roller; The air blowing device according to any one of claims 1 to 9, wherein the air blowing device is arranged upstream of the sheet conveying device in the sheet conveying direction.