Feeding device and image forming apparatus

Abstract

To provide a feeding device suppressed in a failure that a blowing air amount to a sheet cannot be adjusted to the optimum amount for some sheets set in a sheet loading part, and an image forming device.SOLUTION: A feeding device has a sheet loading part such as a sheet loading bed for loading the sheet, and air blowing means such as a side air blowing device 14 having blowing means like a side blower 14a and a duct 14b blowing air blown from the blowing means and blowing air like side air to the sheet. The feeding device has first air volume adjusting means adjusting the air volume of the blowing means by controlling the blowing means and second air volume adjusting means 140 having an air releasing port 141 at the duct 14b and adjusting the air volume blown to the air releasing port 141.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a feeding device and an image forming apparatus. [Background technology]

[0002] Conventionally, a sheet feeding device is known that includes a sheet stacking section for stacking sheets, an air blowing device having an air blowing device and a duct for directing air blown from the air blowing device toward the sheets, and that blows air onto the sheets.

[0003] Patent document 1 describes a feeding device that uses PWM control to adjust the rotation speed of a blower fan, which serves as an air blowing means, based on sheet information set in the sheet stacking section, to adjust the air volume to correspond to the set sheets. Summary of the Invention [Problem to be solved by the invention]

[0004] However, depending on the sheets set in the sheet stacking section, there is a risk that the amount of air blown onto the sheets cannot be adjusted to an optimal amount. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, the present invention provides a sheet feeding device including a sheet stacking section for stacking sheets, a blowing means and a duct for directing air blown from the blowing means toward the sheets, and an air blowing means for blowing air toward the sheets, the sheet feeding device further including a first air volume adjustment means for controlling the blowing means to adjust the volume of air from the blowing means, and a second air volume adjustment means for providing an air escape port in the duct and adjusting the volume of air to be flowed into the air escape port, When the basis weight of the sheets loaded on the sheet stacking section is equal to or greater than a specified value, the volume of air blown onto the sheets is adjusted by a first air volume adjustment means, and when the basis weight of the sheets is less than the specified value, the volume of air blown onto the sheets is adjusted by the first air volume adjustment means and the second air volume adjustment means, and the first air volume adjustment means sets the volume of air blown by the blowing means to a control lower limit value. It is characterized by the above. Effect of the Invention

[0006] According to the present invention, it is possible to suppress the problem that the amount of air blown onto the sheets cannot be adjusted to an optimal amount depending on the sheets set in the sheet stacking section. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic diagram of an image forming apparatus including a feeding device according to an embodiment of the present invention; [Diagram 2] FIG. [Diagram 3] FIG. 2 is a perspective view showing a schematic configuration of one storage tray of the feeding device. [Figure 4] A graph showing the relationship between the rotation speed of the side blower and the duty ratio of the PWM control. [Diagram 5] A graph showing the relationship between the side air volume and the duty ratio of PWM control. [Figure 6] FIG. 13 is a diagram for explaining a conventional air volume adjustment. [Figure 7] FIG. 4 is a schematic diagram of a side blower device equipped with a second air volume adjustment means of the present feeding device. [Figure 8] 6A and 6B are diagrams illustrating air volume adjustment by a second air volume adjustment unit. [Figure 9] FIG. 11 is a schematic diagram showing a second air volume adjustment means according to a modified example. [Figure 10] 10A and 10B are diagrams illustrating air volume adjustment in a modified example. [Figure 11] Graph showing the air volume at each stage when the duty ratio of the side blower's PWM control is set to 20%. [Figure 12] FIG. 4 is a control block diagram of air volume control of the blower based on sheet information. [Figure 13] FIG. 11 is a flow diagram for adjusting the side air volume based on seat information. [Figure 14] 11 is a table showing an example of the shutter rotation stage in the modification example and the basis weight. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An embodiment of a feeding device to which the present invention is applied will be described below. FIG. 1 is a schematic diagram of an image forming apparatus 1 including a feeding device according to this embodiment. 1, the image forming apparatus 1 includes an image forming apparatus main body 100 as an image forming means for forming an image on a sheet, and a feeding device 200 for feeding a sheet to the image forming apparatus main body 100. The feeding device 200 is provided on a side surface of the image forming apparatus main body 100.

[0009] There is no particular limitation on the recording method of the image forming apparatus main body 100, and any method such as electrophotographic method or inkjet method can be adopted. A sheet carrying-in section from the feeding device 200 is provided on the right side surface of the image forming apparatus main body 100 in Fig. 1. This sheet carrying-in section is provided with an opening for receiving a sheet and a conveying means for conveying the sheet.

[0010] FIG. 2 is a schematic diagram of the feeding device 200. As shown in FIG. 2, the feeding device 200 includes upper and lower storage trays 10. Each storage tray 10 includes a sheet placement table 11 as a sheet placement section for placing a sheet stack P. Each storage tray 10 can store, for example, up to about 2500 sheets.

[0011] Examples of the sheet include paper, coated paper, label paper, OHP sheet, film, prepreg, etc. Prepreg is mainly used as a material for laminates and multilayer printed wiring boards. Prepreg is a sheet material processed by continuously impregnating a long substrate such as glass cloth, paper, nonwoven fabric, aramid cloth, etc. with a resin varnish mainly made of a thermosetting resin such as epoxy resin or polyimide resin, heating and drying it, and then cutting it.

[0012] A feeding unit 20 serving as a feeding means for separating and feeding the sheets stacked on the storage tray 10 is disposed above each storage tray 10. The feeding unit 20 includes an adsorption belt 21 and a suction device 23 serving as a conveying means.

[0013] The sheets stacked on the lower storage tray 10 are conveyed to the image forming apparatus main body 100 by the exit roller pair 80 through the lower conveying path 82. The sheets stacked on the upper storage tray 10 are conveyed to the image forming apparatus main body 100 by the exit roller pair 80 through the upper conveying path 81.

[0014] Fig. 3 is a perspective view showing a schematic configuration of one of the storage trays 10 of the feeding device 200. For ease of understanding, Fig. 3 shows the feeding unit 20 shifted in the direction of the arrow A from its original location. The suction belt 21 of the feeding unit 20, which serves as a feeding means, is stretched by two tension rollers 22a and 22b. The suction belt 21 is provided with suction holes that penetrate from the front side to the back side over the entire circumferential area. A suction device 23 is provided inside the suction belt 21.

[0015] The suction device 23 is connected to a suction fan that sucks in air through an air duct, which is an air flow path, and generates a negative pressure downward by the suction device 23, thereby acting to suck the sheet onto the lower surface of the suction belt 21. The air sucked into the suction device 23 is called suction air.

[0016] The storage tray 10 also includes an air blower 17, which is an air blowing means for blowing air onto the upper sheets of the sheet stack P. The air blower 17 includes a front air blower 12 and a side air blower .

[0017] The front blower 12 blows air to the tip of the upper part of the sheet stack P (the end on the downstream side in the feeding direction). The front blower 12 includes a floating outlet that blows air in a direction to float the sheet stack P, a separation outlet that blows air between the uppermost floating sheet and the second floating sheet to separate them, and a floating blower 15 that sends air to the floating nozzle. The front blower 12 also includes a separation blower 16 that sends air to the separation outlet. The front blower 12 also includes a floating shutter that can block air sent to the floating outlet, and a separation shutter that can block air sent to the separation outlet.

[0018] Of the air outlets, the air blown from the floating air outlet is called floating air, and the air blown from the separation air outlet is called separation air. The floating air is blown in the direction of arrow a1 in FIG. 3 from a position facing the leading edge of the upper part of the sheet stack P (end on the downstream side in the feeding direction) and is blown onto the leading edge of the upper part of the sheet stack P (end on the downstream side in the feeding direction). The separation air is blown in the direction of arrow a2 in FIG. 3 from a position facing the leading edge of the upper part of the sheet stack P (end on the downstream side in the feeding direction) and is blown onto the gap between the top sheet adsorbed to the suction belt 21 and the second sheet that has floated up. By blowing separation air between the top sheet and the second sheet that has floated up, the separation air flows toward the upstream side in the sheet conveying direction, separating the top sheet from the second sheet.

[0019] The side blower 14, which is a blowing means, is provided on the side fences 13, which are a pair of sheet regulating members that regulate the widthwise position of the sheet stack, and blows air in the direction indicated by the arrow b in the figure toward the side of the upper part of the sheet stack P. The air blown in the direction indicated by the arrow b in the figure is called side air.

[0020] The side air is blown out from side air outlets 13a, which are outlets for blowing the sheets, provided at the positions of each side fence 13 facing the upper part of the sheet stack P, and is blown onto the side surface of the upper part of the sheet stack P. A side blower 14a, which is a blowing means for sending the side air to the side air outlet 13a, is provided inside the side fence 13. In addition, the side wall of the side fence 13 opposite the side facing the sheets has an air intake 13b. The side blower 14a takes in air from the air intake 13b and sends the side air to the side air outlet 13a.

[0021] In addition, a relief outlet 13c is provided on the side wall opposite to the side facing the seat of the side fence 13. As described later, when adjusting the air volume by the second air volume adjustment mechanism, a part of the air taken in from the intake port 13b is blown out from the relief outlet 13c in the direction shown by the arrow c in the figure to adjust the air volume.

[0022] The air blown from the front blower 12 and the side air outlets 13a of the pair of side fences 13 causes the upper sheets of the sheet stack to float.

[0023] The storage tray 10 also includes an end fence 25 that aligns the rear ends of the sheet stack P stacked on the sheet placement table 11 serving as a sheet placement section. The sheet placement table 11 is configured to be movable up and down in the direction of arrow B in the figure by a lifting device 19 serving as placement section moving means.

[0024] Next, the feeding operation will be described. When a command to start feeding is received from a host controller of the image forming apparatus 100 main body, the lifting device 19 is driven to lift the sheet placement table 11. Then, when the sheet detection sensor detects the top surface of the sheet stack, the lifting device 19 is stopped. Next, with the suction belt 21 stopped, the blowing device 17 starts blowing air, and blowing control is started. Also, the suction device 23 starts suction, and suction control is started. By starting blowing air from the blowing device 17, floating air, separation air, and side air are blown onto the front end of the upper part of the sheet stack from the floating air outlet, separation air outlet, and side air outlet 13a.

[0025] The blowing of the floating air and side air causes the leading edges of multiple sheets at the top of the sheet stack to float, and the suction of the suction device 23 generates negative pressure below the suction belt 21, causing the floated top sheet to be adhered to the suction belt 21. When the top sheet is adhered to the suction belt 21, separation air is blown between the top sheet and the second sheet, and the adhered top sheet is separated from the second and subsequent sheets.

[0026] Next, the suction belt 21 is rotated to feed the top sheet. At this time, if the second or subsequent sheets excessively float or behave erratically and come into contact with the top sheet, they may be transported together with the top sheet. Therefore, the present feeding device 200 stops blowing the front floating air and separation air when starting to feed the top sheet (when rotating the suction belt 21).

[0027] When a predetermined time has elapsed since the start of feeding (when the leading edge of the uppermost sheet is fed to a predetermined next process downstream of the suction belt (for example, a pair of conveying rollers)), suction by the suction device 23 is stopped, and the first sheet adsorbed to the suction belt 21 is released. In addition, the drive of the feeding motor is stopped, and the rotation of the suction belt 21 is stopped.

[0028] When there is a sheet to be fed next, the blowing of the front floating air and the separation air is resumed. Next, the suction device 23 resumes suction of the sheet to the suction belt 21. After that, the same feeding process as described above is performed.

[0029] The appropriate volume of the side air blown onto the sheets varies depending on the basis weight of the sheets, etc. Therefore, the present feeding device 200 controls the rotation speed of the side blower 14a by PWM control based on the sheet information set in the storage tray 10, and adjusts the air volume to an appropriate volume for the sheets. However, the side blower 14a has a rotation speed range in which it can rotate stably.

[0030] Fig. 4 is a graph showing the relationship between the rotation speed of the side blower 14a and the duty ratio of the PWM control. As shown in Fig. 4, the duty ratio of the PWM control and the rotation speed of the side blower 14a have an exponential relationship. In addition, in a low rotation speed region where the duty ratio of the PWM control is less than 20%, the rotation speed of the side blower 14a is not stable with respect to the duty ratio of the PWM control, and the air volume of the side air is not stable. If the air volume of the side air is not stable, the sheets cannot be stably separated, and there is a risk of double feeding or non-feeding.

[0031] FIG. 5 is a graph showing the relationship between the side air volume and the duty ratio of the PWM control. As shown in FIG. 5, the flow rate of the side air at the minimum duty ratio (20% in this embodiment) at which the side blower 14a can be stably rotated is 0.06 [m 3 / min]. In recent years, the need to print on very thin sheets has increased. In order to handle such very thin sheets well, the side air should be set to 0.06 [m 3 / min] is required. Therefore, when controlling the rotation speed of the side blower 14a by PWM control as described above, the air volume is adjusted at a duty ratio of less than 20%, which is not sufficient to rotate the side blower 14a stably. Therefore, the side air volume is not stable for very thin sheets, and there is a risk of double feeding or non-feeding.

[0032] Therefore, it is conceivable to provide a second air volume adjustment means separate from the air volume adjustment by PWM control of side blower 14a, and to use this second air volume adjustment means to adjust the air volume below the side air volume at the minimum duty ratio at which side blower 14a can rotate stably.

[0033] As an example of air volume adjustment different from the air volume adjustment by PWM control of the side blower 14a, there is a configuration as in JP2020-050481A. As shown in Fig. 6, JP2020-050481A has a shutter 242 in a duct 241. As shown in Fig. 6(b), the opening angle of this shutter 242 is adjusted to adjust the degree of narrowing of the flow path in the duct by the shutter 242, thereby adjusting the air volume blown onto the sheet. However, in the configuration shown in FIG. 6, the amount of air flowing from the blower fan to duct 241 does not change, so theoretically the amount of air blown out from duct 241 does not change and the amount of air cannot be adjusted.

[0034] However, in reality, it is believed that the pressure in the duct increases due to the narrowing of the flow path by the shutter 242, and the blower fan is unable to push the air into the duct 241, resulting in a drop in the air volume blown out of the duct 241. Therefore, in the air volume adjustment of JP2020-050481A, since the opening angle θ of the shutter 242 and the air volume blown out of the duct 241 are not proportional to each other, it is necessary to adjust the air volume based on an experimental formula, and the air volume adjustment is not easy. In addition, the drop in the air volume pushed into the duct 241 by the blower fan causes the load on the blower fan to fluctuate, causing the rotation speed of the blower fan to become unstable, which may result in the air being blown onto the sheet to become unstable.

[0035] Therefore, in the present feeding device 200, as a second air volume adjustment means, an escape port for releasing air is provided in the duct, and the amount of air released to this escape port is adjusted by a shutter, thereby making it possible to adjust the air volume.

[0036] Fig. 7 is a schematic diagram of the side blower 14 equipped with the second air volume adjustment means of the sheet feeding device 200. Fig. 7(a) is a schematic diagram of the side blower 14 seen from the outer side in the width direction, and Fig. 7(b) is a schematic diagram of the side blower 14 seen from the downstream side in the sheet conveying direction. The side blower 14 of this embodiment includes a side blower 14a, a duct 14b, and a nozzle 14c. The air intake of the side blower 14a is provided opposite the air intake 13b of the side fence 13. The air outlet of the side blower 14a is opposite the air inlet of the duct 14b.

[0037] Duct 14b is provided with second air volume adjustment means 140 composed of a shutter 142 and an air escape port 141. Shutter 142 opens and closes air escape port 141 provided in duct 14b. Air escape port 141 faces escape outlet 13c of side fence 13. Nozzle 14c is connected to the air outlet of duct 14b, and the nozzle port of the nozzle faces side air outlet 13a of the side fence.

[0038] FIG. 8 is a diagram illustrating air volume adjustment by the second air volume adjustment means 140. As shown in FIG. As shown in FIG. 8, the shutter 142 is supported so as to be freely rotatable at its downstream end in the air flow direction inside the duct, and opens the air escape port 141 by rotating inside the duct as shown in the figure.

[0039] 8, by rotating shutter 142 inwardly of the duct to open it, this shutter 142 acts as an air guide that guides the air inside the duct to air escape port 141. Therefore, the air that hits the shutter inside the duct is guided by the shutter and discharged from air escape port 141. This reduces the amount of side air blown out from side air outlet 13a compared to when shutter 142 is closed. And, the amount of air that hits shutter 142 and is discharged from air escape port 141 changes depending on the opening angle θ of the shutter, making it possible to adjust the amount of side air.

[0040] Moreover, since the air that hits the shutter 142 is almost entirely guided by the shutter 142 and discharged from the air escape port 141, the volume of the side air is almost proportional to the cross-sectional area of ​​the duct 14b narrowed by the shutter 142. This makes it easy to adjust the volume of the side air. Furthermore, since the volume of the air is adjusted by releasing the air in the duct from the air escape port 141, the volume of the air pushed into the duct 14b by the side blower 14a does not decrease due to the adjustment of the volume of the air by the second air volume adjustment means 140. Therefore, the load on the side blower 14a does not fluctuate, and the side blower 14a can be rotated stably, and the volume of the air from the side blower 14a can be stabilized.

[0041] Moreover, the air discharged from the air escape port 141 is discharged from an escape outlet 13c provided on the side wall surface of the side fence 13 opposite to the side wall surface facing the sheets of the sheet placing table 11. Therefore, the air discharged from the air escape port 141 by adjusting the air volume is discharged in a direction that does not affect the sheets on the sheet placing table 11. This makes it possible to prevent the air discharged from the air escape port 141 by adjusting the air volume from affecting sheet handling.

[0042] In this way, the feeding device 200 has the second air volume adjustment means 140 that adjusts the volume of the side air by releasing the air in the duct from the air release port 141 by the shutter. Therefore, when it is difficult to adjust the volume of the air by PWM control of the side blower 14a as the first air volume adjustment means, the air volume can be adjusted by this second air volume adjustment means 140. As a result, when it is not possible to adjust the air volume to the optimum level by adjusting the air volume by PWM control of the side blower 14a, for example, when very thin sheets are set in the storage tray 10, it is possible to adjust the air volume to the optimum level by combining the second air volume adjustment means 140 and adjusting the air volume.

[0043] Next, a modified example of the second air volume adjustment means 140 will be described. FIG. 9 is a schematic diagram showing a modified second air volume adjustment means 140. As shown in FIG. 8. Note that this is a view seen from the upstream side in the sheet conveying direction, and is a view seen from the opposite direction to that of FIG. As shown in Fig. 9, the modified example is provided with a plurality of straightening plates 143a to 143d that divide the duct 14b. As a result, the inside of the duct 14b is branched into five flow paths A to E by these straightening plates. The straightening plates are disposed at equal intervals, and the cross-sectional areas of the five flow paths A to E formed by division by the plurality of straightening plates are equal. The downstream end of each straightening plate in the air flow direction is located on the rotation locus of the tip of the shutter when the shutter 142 rotates, as shown by the dashed line in the figure.

[0044] FIG. 10 is a diagram illustrating air volume adjustment in the modified example. As described above, the downstream end of each straightening vane in the air flow direction is located on the rotation trajectory of the tip of the shutter when the shutter 142 rotates, as shown by the dashed line in the figure. Therefore, when the shutter 142 is rotated, the tip of the shutter 142 comes into contact with the downstream end of each straightening vane in the air flow direction.

[0045] As shown in FIG. 10(a), when the tip of the shutter 142 abuts against the downstream end in the air flow direction of the first straightening plate 143a arranged closest to the air release port 141, almost all of the air flowing through the flow path A is discharged from the air release port 141. As described above, the cross-sectional areas of the five flow paths A to E are equal, so 1 / 5 of the air volume flowing into the duct 14b is discharged from the air release port 141. Therefore, if the air volume flowing into the duct 14b by the side blower 14a is α, the air volume of the side air is adjusted to 4 / 5α. In the case of FIG. 10(b), almost all of the air in the flow paths A and B is discharged from the air release port 141, so that the air volume of the side air is adjusted to 3 / 5α. In the case of FIG. 10(c), almost all of the air in the flow paths A to D is discharged from the air release port 141, so that the air volume of the side air is adjusted to 1 / 5α. In this way, with this modified example, the volume of side air can be adjusted in four stages. By increasing the number of baffles, it is possible to adjust the volume of air more finely.

[0046] FIG. 11 is a graph showing the air volume at each stage when the duty ratio of the PWM control of the side blower 14a is set to 20%. 11, in the modified example, the amount of air blown out from the side air can be proportional to the rotation of the shutter 142, and the amount of air blown out can be easily adjusted. In addition, when the duty ratio of the PWM control of the side blower 14a is set to 20%, the amount of air blown out is 0.06 [m 3 This allows for precise airflow adjustment in the airflow range below [1 / min].

[0047] FIG. 12 is a control block diagram of the air volume control of the blower 17 based on the sheet information. The control unit 30, which serves as a control means for the feeding device 200, is connected to the side blower 14a of the blowing device 17, the floating blower 15, and the separation blower 16. In addition, the control unit 30 is connected to a shutter drive unit 145 that rotates the shutter 142.

[0048] The control unit 30 is configured to receive, for example, sheet information (such as basis weight information) regarding the sheets placed in the storage tray 10, which is input by a user operating an operation panel of the image forming apparatus body, from the image forming apparatus body. This sheet information is stored in a non-volatile memory of the control unit 30. The control unit 30 sets the volume of the side air, floating air, and separation air based on the sheet information such as basis weight stored in the non-volatile memory when feeding the sheets.

[0049] FIG. 13 is a flow diagram of the adjustment of the amount of side air based on the seat information. The control unit 30 checks whether the basis weight of the sheet set in the storage tray 10 is equal to or less than a specified value based on the acquired sheet information set in the storage tray 10 (S2). In this embodiment, the specified value is 42 [g / m 2 When the basis weight exceeds the specified value (No in S2), the air volume can be adjusted by PWM control of the side blower 14a, so the control unit 30 sets the duty ratio of the PWM control based on the basis weight of the sheet (S3).

[0050] On the other hand, if the basis weight is less than the specified value (Yes in S2), the PWM control of the side blower 14a cannot rotate the side blower 14a stably. Therefore, in this case, the control unit 30 sets the duty ratio of the PWM control to 20%, which is the lower limit of the control that allows the side blower 14a to rotate stably (S4). Also, the angle of the shutter 142 is set based on the basis weight (S5).

[0051] FIG. 14 is a table showing an example of the basis weight and the rotation stage of the shutter 142 in the modified example. As shown in FIG. 14, the basis weight is 42 [g / m 2 Even for very thin sheets of less than 1 / 4" thick, the amount of side air can be adjusted to an optimal amount for the sheets by the shutter 142 of the second air volume adjustment means 140. This allows good separation even for very thin sheets, and prevents double feeding and non-feeding from occurring.

[0052] Also, in continuous sheet feeding, when the top sheet of a sheet stack is attracted to the suction belt 21 and feeding of the top sheet is started, the shutter 142 may be rotated to reduce the volume of the side air. This makes it possible to prevent the second and subsequent sheets from excessively floating up or becoming distorted by the side air and coming into contact with the top sheet, thereby preventing double feeding. Also, in continuous sheet feeding, the start-up time until the side air reaches a predetermined volume in the feeding operation for the next sheet can be shortened compared to when the rotation speed of the side blower is reduced by PWM control to reduce the volume of the side air. This makes it possible to quickly float the next sheet, thereby improving the productivity of continuous sheet feeding.

[0053] Although the above has described the adjustment of the side air volume, it is preferable to provide a second air volume adjustment means similar to that for the side air for the floating air and separation air. As a result, when the basis weight of the sheet set in the storage tray 10 is less than the specified value, the duty ratio of the PWM control of the floating blower 15 and separation blower 16 is set to 20% of the lower limit control value, and the air volume is adjusted by the second air volume adjustment means. As a result, the floating air and separation air can also be adjusted to the optimal air volume for very thin sheets.

[0054] The above description is merely an example, and each of the following aspects provides unique effects. (Aspect 1) The feeding device 200 has a sheet stacking section such as a sheet placing table 11 for stacking sheets, air blowing means such as a side blower 14a, and a duct 14b for directing air blown from the air blowing means toward the sheets, and is equipped with air blowing means such as a side air blower 14 for blowing air such as side air toward the sheets.The feeding device 200 has a first air volume adjustment means for controlling the air blowing means to adjust the volume of air from the air blowing means, and a second air volume adjustment means 140 for providing an air escape port 141 in the duct 14b and adjusting the volume of air flowing into the air escape port 141. There is a control range in which the blowing means such as the side blower 14a can rotate stably. When very light sheets are loaded on a sheet stacking section such as the sheet placement table 11, the rotation speed of the blowing means that provides the optimum air volume for the sheets may fall below the lower limit of the control range in which the sheets can rotate stably. As a result, it may not be possible to handle light sheets such as thin paper with the optimum air volume. In the first aspect, when it is difficult to adjust the volume of air blown onto the sheets using the first air volume adjustment means that controls the blowing means to adjust the volume of air from the blowing means, it is possible to adjust the volume of air blown onto the sheets to an optimal volume by combining the second air volume adjustment means. As a result, even when very thin sheets are loaded on the sheet stacking section, the first air volume adjustment means and the second air volume adjustment means can adjust the volume of air blown onto the sheets to an optimal volume.

[0055] (Aspect 2) In aspect 1, based on information about sheets loaded on a sheet stacking section such as a sheet loading table 11, it is set whether the volume of air such as side air blown onto the sheets is adjusted by the first air volume adjustment means or by using the first air volume adjustment means and the second air volume adjustment means 140. According to this, as described in the embodiment, it is possible to blow an optimum amount of air depending on the sheets stacked on the sheet stacking unit such as the sheet placement table 11.

[0056] (Aspect 3) In aspect 2, the sheet information is the basis weight of the sheet, and when the basis weight of the sheet is equal to or greater than a specified value, the volume of air such as side air blown onto the sheet is adjusted by a first air volume adjustment means, and when the basis weight of the sheet is less than the specified value, adjustment is made using the first air volume adjustment means and the second air volume adjustment means. According to this, as described in the embodiment, it is possible to blow an optimal amount of air onto a very thin sheet whose basis weight is less than a specified value.

[0057] (Aspect 4) In the third aspect, when the basis weight of the sheet is less than a specified value, the first air volume adjustment means sets the air volume of the air blowing means such as the side blower 14a to the lower control limit value (in this embodiment, the duty ratio is 20%). This allows the rotation speed of the blowing means to be stably controlled, and the air volume can be adjusted to be equal to or lower than the air volume at the above-mentioned lower control limit value by the second air volume adjustment means 140. This makes it possible to blow an optimal volume of air onto a very thin sheet whose basis weight is less than a specified value.

[0058] (Aspect 5) In any of the first to fourth aspects, the air escape port 141 is provided between an inlet into which air flows in from a blowing means such as the side blower 14a of the duct 14b, and the blowing nozzle 14c which blows the air toward the sheet. According to this, by releasing the air from the air release port 141, the amount of air blown from the nozzle 14c to the sheet is reduced, and the amount of air blown to the sheet can be adjusted. (Aspect 6) In any of aspects 1 to 5, the second air volume adjustment means 140 has a shutter 142 that opens and closes the air release port 141, and the shutter 142 is configured to open the air release port 141 by rotating from a closed position that closes the air release port 141 toward the inside of the duct, and the air volume is adjusted by the opening angle of the shutter 142 relative to the air release port 141. According to this, as described in the embodiment, by rotating the shutter 142 from the closed position where the air escape port 141 is closed toward the inside of the duct, the air inside the duct is guided by the shutter 142 to the air escape port 141, and the air inside the duct can be discharged from the air escape port 141. Then, by changing the opening angle of the shutter 142, the amount of air guided by the shutter 142 to the air escape port 141 changes, and it is possible to adjust the amount of air, such as side air, blown onto the seat.

[0059] (Aspect 7) In the sixth aspect, a plurality of flow straightening plates that divide the inside of the duct to form a plurality of flow paths are provided upstream of air release port 141 in the duct in the air flow direction. According to this, as described in the modified example, it is possible to form a flow path in the duct by the shutter 142 and the straightening plate for causing air to flow to the air escape port 141. This makes it possible to adjust the air volume with high precision.

[0060] (Aspect 8) In aspect 7, the tip of the shutter 142 is configured to contact the downstream end of the straightening vane in the air flow direction, and the second air volume adjustment means adjusts the air volume by selectively switching the straightening vane with which the tip of the shutter 142 contacts. According to this, as explained in the modified example, a flow path for flowing air to air release port 141 can be formed in the duct by shutter 142 and the straightening plate, and the air volume can be adjusted with high precision.

[0061] (Aspect 9) In any one of the first to eighth aspects, the amount of air such as side air blown onto the sheets is temporarily changed by using the second air amount adjustment means 140 during continuous feeding. This, as described in the embodiment, makes it possible to reduce the start-up time until the air blown onto the sheet reaches a predetermined volume during the feeding operation of the next sheet in continuous sheet feeding, compared to when the air volume is changed by the first air volume adjustment device. This makes it possible to quickly lift the next sheet, thereby improving the productivity of continuous sheet feeding.

[0062] (Aspect 10) In any one of the aspects 1 to 9, the air escape port 141 is configured to blow out air in a direction that does not affect the sheets stacked on the sheet stacking unit such as the sheet placement table 11. According to this, as described in the embodiment, it is possible to suppress the air blown out from the air escape port 141 from affecting the floating, separation and feeding of the sheet.

[0063] (Aspect 11) In an image forming apparatus for forming an image on a sheet fed by a feeding device, the feeding device according to any one of the embodiments 1 to 10 was used as the feeding device. This can prevent the occurrence of feeding failures. [Explanation of symbols]

[0064] 1: Image forming device 10: Storage tray 11: Sheet placement table 12: Front air blower 13: Side fence 13a: Side air outlet 13b: Air intake 13c: Vent for relief 14: Side blower 14a: Side blower 14b: Duct 14c: Nozzle 15: Floating Blower 16: Separation blower 17: Blower 19: Lifting device 20: Feeding unit 21: Suction belt 23:Suction device 25: End fence 30: Control section 100: Image forming apparatus body 140:Second air volume adjustment means 141: Air release port 142: Shutter 143: Rectifier plate 145: Sitter drive unit 200:Feeding device [Prior art documents] [Patent documents]

[0065] [Patent Document 1] JP 2016-79013 A

Claims

1. a sheet stacking section for stacking sheets; A feeding device including a blowing means and an air blowing means having a duct for blowing air from the blowing means toward the sheet, the air blowing means blowing air onto the sheet, a first air volume adjustment means for controlling the blowing means to adjust the volume of air from the blowing means; an air release port is provided in the duct, and a second air volume adjustment means is provided for adjusting the volume of air flowing through the air release port; When the basis weight of the sheets stacked on the sheet stacking section is equal to or greater than a specified value, a first air volume adjustment means adjusts the volume of air blown onto the sheets, A feeding device characterized in that, when the basis weight of the sheet is less than a specified value, adjustment is made using a first air volume adjustment means and a second air volume adjustment means, and the first air volume adjustment means sets the air volume of the blowing means to a control lower limit value.

2. A sheet stacking section for stacking sheets; A feeding device including a blowing means and an air blowing means having a duct for blowing air from the blowing means toward the sheet, the air blowing means blowing air onto the sheet, a first air volume adjustment means for controlling the blowing means to adjust the volume of air from the blowing means; an air release port is provided in the duct, and a second air volume adjustment means is provided for adjusting the volume of air flowing through the air release port; The second air flow rate adjusting means has a shutter that opens and closes the air release port, a plurality of straightening plates are provided in the duct on the upstream side of the air release port in the air flow direction, the straightening plates dividing the duct to form a plurality of flow paths; the shutter is configured to open the air release port by rotating from a closed position where the air release port is closed toward an inner side of the duct, The feeding device is characterized in that the amount of airflow is adjusted by changing the opening angle of the shutter relative to the air escape port.

3. In the feeding device according to claim 2, The tip of the shutter is configured to contact the downstream end of each straightening plate in the air flow direction, The second air flow rate adjusting means adjusts the air flow rate by selectively switching a straightening plate with which the tip of the shutter comes into contact.

4. A sheet stacking section for stacking sheets; A feeding device including a blowing means and an air blowing means having a duct for blowing air from the blowing means toward the sheet, the air blowing means blowing air onto the sheet, a first air volume adjustment means for controlling the blowing means to adjust the volume of air from the blowing means; an air release port is provided in the duct, and a second air volume adjustment means is provided for adjusting the volume of air flowing through the air release port; A sheet feeding device, comprising: a second air volume adjusting means for temporarily changing the volume of air blown onto the sheet during continuous feeding.

5. The feeding device according to any one of claims 1 to 4, The feeding device, wherein the air escape port is provided between an inlet of the duct through which air flows in from the blowing means and a blowing nozzle that blows air toward the sheet.

6. In the feeding device according to any one of claims 1 to 5, The sheet feeding device according to claim 1, wherein the air escape port is configured to blow out the air in a direction that does not affect the sheets stacked on the sheet stacking portion.

7. An image forming apparatus for forming an image on a sheet fed by a feeding device, 7. An image forming apparatus, comprising: a feeding device according to claim 1;

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