JP2020050481A - Sheet feeding device and image forming system - Google Patents

Abstract

To provide a sheet feeding device and an image forming system, capable of preventing an excessive decrease in water content of sheets stacked on sheet stacking means and improving the quality of a product.SOLUTION: A feeding deck includes: a lift plate capable of loading a plurality of sheets; a pickup roller for feeding the sheets; and air blowing means having a shutter 615a for adjusting a height of a flow path at an adjustment position, and for separating a plurality of sheets including the upperamost sheet of the sheets stacked on the lift plate. When a length of the sheets stacked on the lift plate in a sheet feeding direction is a first length, the shutter 615a operates in a first mode in which the maximum height of the flow path at the adjustment position is adjusted to be a first height h1. When the length of the sheets stacked on the lift plate in the sheet feeding direction is a second length longer than the first length, the shutter operates in a second mode in which the maximum height of the flow path at the adjustment position is adjusted to be a second height h2 smaller than the first height h1.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a sheet feeding device for feeding a sheet and an image forming system including the same.

  In recent years, in image forming apparatuses such as copying machines and printers, recording media used for image formation have been diversified. Coated paper, such as an OHT (Overhead Transparency) sheet, tracing paper, art paper, or coated paper, which is an example of a recording medium, has a property that the surface is smooth and gas does not easily pass through. When such a sheet having a smooth surface and a property of preventing gas from passing therethrough is stacked in a paper feed unit under a high humidity environment, the sheets are easily attracted to each other, so that the sheets are conveyed in an overlapping state. Double feed is likely to occur. In view of this, a technique has been proposed in which air is blown onto paper stacked in a paper feeding unit by a blowing means to separate the paper and eliminate the attraction between the papers (see Patent Document 1).

JP 2014-16386 A

  However, when the paper is separated by blowing hot air as in the blowing means described in Patent Literature 1, if the blowing time of the hot air on the paper to be fed is too long, the water content of the paper is excessively reduced. Sometimes. In particular, when the paper loaded on the paper feeding unit is long paper, the wiping time of warm air tends to be long. An excessive decrease in the amount of water in the paper causes deterioration in image quality such as toner image omission, and also causes wrinkles on the paper when the toner image is fixed on the paper in the fixing unit. It causes a decline.

  In view of the above, an object of the present invention is to provide a sheet feeding apparatus that solves the above-described problem and suppresses an excessive decrease in the moisture content of sheets stacked on a sheet stacking unit, and an image forming system including the sheet feeding apparatus. I do.

  According to the present invention, in a sheet feeding apparatus, a sheet stacking unit capable of stacking a plurality of sheets, a sheet feeding unit configured to feed a sheet stacked on the sheet stacking unit in a sheet feeding direction, and rotating. A blower that blows air, an opening that blows out the air blown by the blower, a duct that forms a flow path through which air flows between the blower and the opening, and an upper surface facing the duct. And an adjustment unit that adjusts the height of the flow path at the adjustment position by changing the distance between the sheet stacking unit and the sheet stacking unit by air blown out from the opening. Air blowing means for separating a plurality of sheets including the top sheet from among the sheets from the top sheet to the bottom sheet to be processed, and the adjustment section is loaded on the sheet loading section. Operating in a first mode in which the maximum height of the flow path at the adjustment position is adjusted to the first height when the length of the sheet in the sheet feeding direction is the first length. When the length of the sheets stacked on the sheet stacking unit in the sheet feeding direction is a second length longer than the first length, the maximum height of the flow path at the adjustment position is The device operates in a second mode adjusted to have a second height smaller than the first height.

  According to the present invention, it is possible to prevent the water content of the sheet from excessively decreasing and improve the quality of the product.

1 is an overall schematic diagram illustrating a configuration of an image forming system according to a first embodiment. Sectional drawing which shows the internal structure of a feeding deck. FIG. 3 is a perspective view showing a feeding deck. FIG. 4 is a plan view showing a feeding deck in a state where a storage is opened. (A) is a front view showing an opening, and (b) is a side view showing an opening. FIG. 3 is a block diagram showing a control unit. 9 is a graph illustrating a relationship between a sheet position and a sheet moisture content in a sheet feeding direction. 4 is a graph showing a relationship between a hot air blowing time and a sheet moisture content Wp for each heater temperature. The graph which showed the relationship between the hot air blowing time and the sheet moisture content Wp for every wind speed. FIG. 7A is an explanatory diagram illustrating an operation of a shutter when feeding a normal sheet, and FIG. 7B is an explanatory diagram illustrating an operation of the shutter when feeding a long sheet. (A) is a graph showing the relationship between the number of fed sheets and the sheet moisture content Wp, and (b) is a graph showing the relationship between the elapsed time from the start of feeding and the sheet moisture content Wp. 9 is a flowchart illustrating sheet feeding control. 5 is a flowchart illustrating each process of an initial loosening process according to the first embodiment. FIG. 4 is an explanatory diagram illustrating an example of a setting screen displayed on the display operation unit. Explanatory drawing which shows an example of the table for setting a heater temperature. Explanatory drawing which shows an example of the table for setting of a fan output. FIG. 4 is an explanatory diagram illustrating an example of a setting screen displayed on the display operation unit. 9 is a flowchart illustrating each process of an initial loosening process according to the second embodiment.

<First embodiment>
〔overall structure〕
A first embodiment of the present invention will be described. In the following description, the directions of up, down, left, right, back, and front are represented with reference to a state in which the printer 100 as an image forming apparatus is viewed from substantially the front (the viewpoint in FIG. 1). As shown in FIG. 1, the image forming system 800 according to the first embodiment includes a printer 100 and a feed deck 250 that feeds sheets to the printer 100. The feeding deck 250 is an external device of the printer 100, and is configured to be connectable to the printer 100. The feeding deck 250 serving as a sheet feeding device can feed sheets P stacked and stored in the feeding deck 250 into the printer 100 by connecting to the printer 100.

  The printer 100 is an electrophotographic laser beam printer. As illustrated in FIG. 1, the printer 100 controls a sheet feeding unit 240 that feeds the stacked sheets P, an image forming unit 120 that forms an image on the fed sheet P, and an image forming operation. And a control unit 700 that performs the operation. Further, the printer 100 includes a fixing device 170 for fixing the image transferred to the sheet P, and a pair of discharge rollers 13 and 12 for discharging the sheet P after image fixing to the discharge trays 27 and 200. The discharge tray 27 is disposed on the upper part of the apparatus main body 110, and the discharge tray 200 is disposed on the left side of the apparatus main body 110.

  The image forming unit 120 constitutes a so-called four-drum full-color image forming unit including a laser scanner 122, four process cartridges 123, and an intermediate transfer unit 130. The process cartridge 123 forms a toner image of each color of yellow (Y), magenta (M), cyan (C), and black (K). Each process cartridge 123 has a photosensitive drum 5, a developing device 6, a charging device 7, a cleaner 8, and the like. Above the image forming unit 120, a toner cartridge 121 containing toner of each color is detachably mounted to the apparatus main body 110.

  The intermediate transfer unit 130 includes an intermediate transfer belt 9d, which is an intermediate transfer member, primary transfer rollers 10Y, 10M, 10C, and 10K, a driving roller 9a, a tension roller 9b, and a secondary transfer inner roller 9c. doing. The intermediate transfer belt 9d is supported by being wound around rollers such as a drive roller 9a, a tension roller 9b, and a secondary transfer inner roller 9c, and is rotated in the direction of arrow D1 shown in FIG. I do. Further, the intermediate transfer belt 9d is arranged below the four process cartridges 123 so as to contact the photosensitive drum 5 of each process cartridge 123.

  The primary transfer rollers 10Y, 10M, 10C, and 10K are arranged so as to abut on the inner peripheral surface of the intermediate transfer belt 9d at positions facing the photosensitive drums 5 of the respective colors. A primary transfer portion is formed by the photosensitive drum 5 of each color and the intermediate transfer belt 9d. Further, an outer secondary transfer roller 11 is provided at a position facing the inner secondary transfer roller 9c with the intermediate transfer belt 9d interposed therebetween. The secondary transfer outer roller 11 is in contact with the outer peripheral surface of the intermediate transfer belt 9d. A secondary transfer portion is formed by the intermediate transfer belt 9d and the secondary transfer outer roller 11.

  The sheet feeding unit 240 includes cassettes 150 and 220 for stacking the sheets P and a manual feed tray 210. The cassettes 150 and 220 are disposed, for example, below the apparatus main body 110 and are configured to be insertable into and removable from the apparatus main body 110. The manual feed tray 210 is disposed on the right side of the apparatus main body 110.

  When the printer 100 receives an instruction to start an image forming operation, the photosensitive drum 5 rotates, and the surface of the photosensitive drum 5 is uniformly charged by the charger 7. Then, the laser scanner 122 modulates and outputs the laser light based on image data input from the input interface or an external computer. The laser scanner 122 outputs a laser beam and scans the surface of each photosensitive drum 5 to form an electrostatic latent image on the surface of each photosensitive drum 5 based on image data. That is, electrostatic latent images of yellow (Y), magenta (M), cyan (C), and black (K) are sequentially formed on the photosensitive drum 5 of each process cartridge 123, respectively. The formed electrostatic latent images of yellow, magenta, cyan and black are visualized by the toner supplied from the developing device 6 to become toner images of yellow, magenta, cyan and black, respectively. The yellow, magenta, cyan, and black toner images formed on each photosensitive drum 5 are sequentially applied to the intermediate transfer belt 9d by applying a transfer voltage to the primary transfer rollers 10Y, 10M, 10C, and 10K. Transcribed and superimposed. Thus, a full-color toner image is formed on the intermediate transfer belt 9d. The toner remaining on each photosensitive drum 5 after the transfer of the toner image is collected by the cleaner 8.

  On the other hand, in the printer 100, in parallel with such an image forming operation, the sheet feeding unit 240 picks up the sheet P from the storage location of the selected sheet P and feeds the sheet P to the image forming unit 120. . In the case of the printer 100 illustrated in FIG. 1, one place for storing the sheet P is selected from any one of the cassette 150, the cassette 220, the manual feed tray 210, and the feeding deck 250. Here, a case where the cassette 150 is selected will be described as an example of the storage location of the sheet P.

  When the cassette 150 is selected as a storage location for the sheets P, the sheets P stacked on the cassette 150 are sent out by the pickup roller 151 and separated one by one by the feed roller 22 and the separation roller 21. The sheets P separated one by one are conveyed to a registration roller pair (hereinafter, referred to as a “register roller pair”) 161 by conveyance roller pairs 153, 154, and 155 arranged in the conveyance path 20. The skew of the sheet P conveyed to the registration roller pair 161 is corrected by the front end abutting on the nip of the registration roller pair 161. Thereafter, the sheet P is conveyed to the secondary transfer unit in time with the toner image carried on the intermediate transfer belt 9d. The toner image carried on the intermediate transfer belt 9d is collectively transferred onto the sheet P by a secondary transfer bias applied to the outer secondary transfer roller 11. The sheet P to which the toner image has been transferred is conveyed to the fixing device 170, and heat and pressure are applied by the fixing roller 171 and the pressure roller 172. Thus, the toner image on the sheet P is fixed on the sheet P.

  When the image formation on the sheet P on which the toner image is fixed has been completed, the transport destination is switched to the transport path 231 by the switching member 173 and transported to the transport path 231. The sheet P conveyed to the conveyance path 231 is guided from the conveyance path 231 to the discharge path 180 by the switching member 174 provided in the conveyance path 231 when the discharge tray 200 is selected as the discharge destination. The sheet P guided to the discharge path 180 is discharged to the discharge tray 200 by the discharge roller pair 12 disposed in the discharge path 180. When the discharge tray 27 is selected as the discharge destination, the sheet P conveyed to the conveyance path 231 is guided from the conveyance path 231 to the discharge path 181 by the switching member 174. The sheet P guided to the discharge path 181 is discharged to the discharge tray 27 by the discharge roller pair 13 disposed in the discharge path 181.

  On the other hand, when an image is formed on both sides of the sheet P, the sheet P on which the image is formed on the first surface is guided to the reverse conveyance path 17 by the switching member 173. The sheet P guided to the reverse transport path 17 is once transported to the reverse transport path 16 by the transport roller pairs 14 and 15. After the sheet P is transported to the reverse transport path 16, the transport roller pair 15 is reversed, and is transported to the double-side transport path 18 by the reverse transport roller pair 15 and the switching member 175. The sheet P conveyed to the double-sided conveyance path 18 is conveyed from the double-sided conveyance path 18 to the conveyance path 20 by the conveyance roller pair 19, and conveyed to the registration roller pair 161. After that, an image is formed on the second surface of the sheet P in the same manner as when forming the image on the first surface.

[Feeding deck]
Next, the feeding deck 250 will be described in detail. As shown in FIGS. 1 to 3, the feeding deck 250 includes a lift plate 507 as a sheet stacking unit capable of stacking a plurality of sheets P, a storage 506 for storing the lift plate 507, and a lift plate 507. And a lifting mechanism 530 for lifting and lowering. The storage 506 can be opened and closed with respect to the deck main body by pressing a storage opening / closing button 510.

  The storage 506 is a long sheet in which the length of the sheet P in the sheet feeding direction indicated by the arrow D2 (see FIG. 2) (hereinafter, simply referred to as “sheet length”) is longer than a generally used sheet. Can be stored. In this embodiment, the long sheet refers to a sheet having a sheet length exceeding 19 inches (about 482.6 mm). A sheet having a sheet length of 19 inches or less, that is, a sheet having a shorter sheet length than a long sheet is referred to as a normal sheet.

  The feed deck 250 includes a pickup roller 501 that feeds the uppermost sheet P stacked on the lift plate 507, a feed roller 502 that separates and feeds the fed sheet P one by one, and And a roller 503. The sheets P separated one by one by the feed roller 502 and the separation roller 503 are drawn into the printer 100 by the drawing rollers 504 and 505 provided in the printer 100. The outer peripheral surfaces of the pickup roller 501, the feed roller 502, the separation roller 503, and the pull-in rollers 504 and 505, which come into contact with the sheet P, are formed of members having a high coefficient of friction. Examples of the member having a high friction coefficient include rubber.

  As shown in FIG. 2, the lifting mechanism 530 includes two driven pulleys 530b, and a lifter motor 500 that hoists and lowers a wire 530a that is wound around the two driven pulleys 530b. One end of the wire 530a is connected to the lift plate 507, and the other end is connected to the lifter motor 500. The lift plate 507 is raised by the lifter motor 500 winding up the wire 530a, and is lowered by the lifter motor 500 winding down the wire 530a. The wires 530a are connected to both ends of the lift plate 507 in the width direction, respectively, so that the lift plate 507 can be moved up and down stably.

  Further, inside the feed deck 250, a sheet presence / absence detection sensor 601, a sheet height detection sensor 602, a feed sensor 603, a bottom position detection sensor 604, and a supply position detection sensor 605 are provided. Further, the storage 50 is provided with a storage opening / closing detection sensor 608 for detecting opening and closing of the storage 506, and an environment sensor 614 (see FIG. 6) not shown in FIG.

  Here, the sheet presence / absence detection sensor 601 is a sensor that detects the presence / absence of a sheet P stacked on the lift plate 507, and is disposed, for example, near the pickup roller 501 as a sheet feeding unit. The sheet height detection sensor 602 is a sensor that detects whether the uppermost surface of the sheets P stacked on the lift plate 507 is located at a feeding position where feeding by the pickup roller 501 can be performed. It is arranged near 501. The feed sensor 603 detects that the sheet P stacked on the lift plate 507, that is, the sheet P stored in the feed deck 250, is an outlet (hereinafter, “feed port”) where the sheet P is fed from the feed deck 250. ") Is detected. The feed sensor 603 is disposed, for example, near the feed port, and can detect that the leading end and the trailing end of the sheet P in the sheet feeding direction have passed through the feed port.

  The bottom position detection sensor 604 and the replenishment position detection sensor 605 detect the position of the lift plate 507 in the loading direction. The bottom surface position detection sensor 604 is a sensor that is disposed below the storage 506 and detects that the lift plate 507 is at the lowest position in the storage 506. The replenishment position detection sensor 605 is disposed below the separation roller 503, and detects that the remaining amount of the sheets P stacked on the lift plate 507 is low based on the position of the lift plate 507 in the stacking direction. It is. The environment sensor 614 is a sensor that detects an environment state including the temperature (air temperature) and humidity of the atmosphere inside the storage 506, that is, around the sheet P stacked on the lift plate 507.

  Further, as shown in FIGS. 2 to 4, the feed deck 250 includes a rear end regulating plate 2 that regulates a rear end position of the sheets P stacked on the lift plate 507 in the sheet feeding direction, and both ends in the width direction. And the side regulating plates 610a and 610b for regulating the position of. In FIG. 3, the width direction indicated by arrow D4 is a direction orthogonal to the sheet feeding direction indicated by arrow D2.

[Air blowing means]
As shown in FIG. 4, the side regulating plate 610 a has a separating air for separating sheets into a plurality of sheets including the highest sheet among the sheets from the highest sheet to the lowest sheet stacked and stored in the storage 506. Air blowing means 620 for blowing air. The air blowing means 620 discharges a warm air blowing part 620a that discharges a wind (hereinafter, referred to as “hot air”) 24a whose temperature is equal to or higher than the temperature of the atmosphere in the storage 506, and discharges the atmosphere as the cool air 24b. Cold air blowing part 620b.

  The hot-air blowing unit 620a has a fan 611a as a blower, an air heater 613 as a heater, a shutter 615a as an adjusting unit and a swinging member, and an opening 612a through which the hot air 24a as separating air blows. ing. An intake duct 618 and an exhaust duct 617a are connected to the intake side and the exhaust side of the fan 611a, respectively. The air heater 613 is provided inside the intake duct 618. The shutter 615a as an adjusting unit is disposed near the opening 612a, which is the outlet of the exhaust duct 617a, and adjusts the height of the flow path FP formed in the exhaust duct 617a to the height of the exhaust duct 617a. It is configured to be adjustable within the range.

  More specifically, as shown in FIGS. 5A and 5B, the shutter 615a is disposed so as to face the upper surface 619 of the exhaust duct 617a and swings at the lower end of the exhaust duct 617a. The upper end is configured to be swingable about the shaft 616a. The swing shaft 616a is connected to the shutter motor M1, and the shutter 615a can swing in the air blowing direction by the drive transmission from the shutter motor M1. The shutter 615a adjusts the height of the flow path FP at the adjustment position, that is, the flow path height h, by changing the distance from the upper surface 619 of the exhaust duct 617a. The shutter 615a is controlled by a control unit 700 (see FIG. 6) described later so that the pickup roller 501 swings continuously during a feeding job for feeding sheets from the viewpoint of enhancing the effect of sheet separation. Is done.

  As shown in FIG. 4, the cool air blowing unit 620b includes a fan 611b as a blower, a shutter 615b as an adjusting unit and a swinging member, an exhaust duct 617b as a duct, and an opening through which the cool air 24b as loose air blows. 612b. The fan 611b, the shutter 615b, the exhaust duct 617b, and the opening 612b are configured similarly to the fan 611a (see FIG. 4), the shutter 615a (see FIG. 5A), the exhaust duct 617a, and the opening 612a, respectively.

  Further, as shown in FIG. 3, the opening 612a in the hot air blowing section 620a and the opening 612b in the cold air blowing section 620b are at the height of the pickup roller 501 (see FIG. 2) in the height direction indicated by the arrow D3. It is arranged correspondingly. Further, the opening 612a is disposed so as to overlap with the contact portion where the pickup roller 501 at the feeding position and the uppermost sheet stored in the storage 506 contact each other when viewed in the width direction indicated by the arrow D4. .

  In the feeding deck 250 configured as described above, a long sheet can be stored in the storage 506, and the rear end of the sheet P stored in the storage 506 in the sheet feeding direction is the rear end regulating plate 2. It is positioned by moving it. Further, both ends in the width direction of the sheet P are positioned by moving the side regulating plates 610a and 610b. Note that the exhaust duct 617a shown in FIGS. 5A and 5B is a representative example of one of the exhaust ducts 617a and 617b. That is, the exhaust duct 617b, which is the other of the exhaust ducts 617a and 617b, has the same configuration as the exhaust duct 617a.

(Control unit)
Control unit 700 controls an image forming operation in image forming system 800 (see FIG. 1). As shown in FIG. 6, the control unit 700 has a CPU 301, a memory 302, an I / O port 303, and a communication interface 304. Further, the control unit 700 can electrically communicate with each of the display operation unit 310, which is a user interface (hereinafter, referred to as “UI”), the host device 600, the image forming unit 120, the fixing device 170, and the storage control unit 320. It is connected to the.

  The storage control unit 320 is communicably connected to each of components including an interface for receiving a command input, a timer, various sensors, devices to be controlled, and the like. The interface includes a storage opening / closing button 510 that receives an input of a command to open and close the storage 506 (see FIG. 1) from the user. The timer includes, for example, a timer 26 that measures an elapsed time from a designated timing, such as a time from the start of blowing the loose air onto the sheet P. Various sensors include a storage opening / closing detection sensor 608, a bottom position detection sensor 604, a replenishment position detection sensor 605, an environment sensor 614, a sheet presence / absence detection sensor 601, a sheet height detection sensor 602, a size detection sensor 4, and a feeding sensor. 603 are included. The devices to be controlled by the storage controller 320 include the storage opening / closing solenoid 23, the lifter motor 500, the air heater 613, the shutter motor M1, and the fans 611a and 611b. The storage opening / closing solenoid 23 is a solenoid incorporated in a latch member (not shown) of the storage 506, and receives a command to open and close the storage 506 by a storage opening / closing button 510, and locks the storage 506. Open and close.

[Relationship between sheet moisture content and double feed and paper wrinkles]
Next, the moisture content of the sheet P (hereinafter, referred to as “sheet moisture content”) and the wrinkles of the sheet P (hereinafter, referred to as “sheet moisture content”) generated when the toner image is fixed in the double feeding and fixing device 170 (see FIG. The relationship with “paper wrinkles”) will be described. In the present description, the time for blowing the hot air 24a (see FIG. 4) onto the sheet P (hereinafter, referred to as “hot air blowing time”), the set temperature of the air heater 613 (hereinafter, referred to as “heater temperature”), and the temperature of the fan 611a We focused on three parameters of wind speed.

  First, the relationship between the sheet moisture content and the hot air blowing time will be described. The graph shown in FIG. 7 shows that the type, the basis weight and the size of the sheet P stored in the storage 506 (see FIG. 1), the heater temperature and the blowing position are not changed, and the hot air blowing time is changed in six ways. 4 shows a relationship between a sheet position and a sheet moisture content in a sheet feeding direction when wind is applied. Specifically, curves C1 to C6 shown in FIG. 7 represent sheet moisture amounts when the warm air blowing time is 10 seconds, 50 seconds, 100 seconds, 180 seconds, 240 seconds, and 360 seconds, respectively. I have.

7, the type, basis weight, and size of the sheet P used to obtain the results shown in FIG. 7 are coated paper, 80 [g / m ² ] and A3 size (297 [mm] × 420 [mm]). Further, the position [mm] of the sheet feeding direction on the horizontal axis is defined as 0 [mm] at the tip located at the most upstream position in the sheet feeding direction of the sheet P stored in the storage 506 (see FIG. 1). I have. Further, the position where the sheet feeding direction position is x [mm] is the center position in the sheet feeding direction of the opening 612a for blowing the hot air 24a (see FIG. 5B) onto the sheet P, and is shown in FIG. In the example, x = 70 [mm]. The sheet water content Wp is the water content at the position where the position of the sheet feeding direction is x [mm] where the water content is the lowest. Further, the sheet moisture content W is an average moisture content of the sheet P in a portion other than the portion where the hot air 24a is blown.

  As shown in FIG. 7, the sheet moisture amount Wp decreases as the hot air blowing time increases to 10 seconds, 50 seconds, 100 seconds, 180 seconds, 240 seconds, and 360 seconds. Further, the sheet moisture content W was hardly affected by the difference in the hot air blowing time.

  Next, with reference to FIG. 8, how the sheet moisture amount Wp changes with respect to the hot air blowing time when the heater temperature is changed will be described. The sheet P used to obtain the result shown in FIG. 8 is the same as the sheet P used to obtain the result shown in FIG. Curves C7, C8, and C9 shown in FIG. 8 show changes in the sheet moisture amount Wp with respect to the hot air blowing time when the heater temperature is 60 ° C., 90 ° C., and 110 ° C., respectively. . Comparing the slopes of the water content decrease in the curves C7, C8, and C9 when the hot air blowing time is 0 to 50 seconds, the higher the heater temperature, the larger the slope of the water content decrease, and the faster the water content decrease per unit time. I understand. Further, it was found that the sheet moisture amount Wp indicated by the curves C7, C8, and C9 hardly changed when the hot air blowing time was 300 seconds or more. Furthermore, it was found that the higher the heater temperature, the lower the amount of water finally converging, and the faster the time until the water converges to this amount of water. When the heater temperature is 90 ° C. and 110 ° C., the finally converged sheet moisture amount Wp falls within the range R2, that is, as described later, paper wrinkles occur at the time of fixing the toner image. It turns out that it decreases so that it is made.

Next, the results of an experiment performed by the inventor on the relationship between the sheet moisture content Wp of the sheet P and the occurrence of double feeding and paper wrinkling will be described. This experiment was performed in a room where the temperature was 30 [° C.] and the humidity was 80 [%], and the type, the basis weight [g / m ² ], and the size of the sheet P used obtained the results shown in FIG. 7, respectively. It is the same as the type, basis weight [g / m ² ] and size of the sheet P used for this purpose. The sheet moisture content Wp of the sheet P at the start of the experiment was set to 8.0 [%].

  As a result of this experiment, the present inventor has found that in order to reduce the adsorption between the sheets and feed the sheets P without causing double feeding, the sheet moisture amount Wp becomes 7.4% or less. It was found that it was necessary to lower it. The range of the sheet moisture amount Wp (Wp ≦ 7.4 [%]) for preventing double feeding of the sheet P is a range R1 shown in FIG. 8 and FIG. 9 described later. More specifically, in order to feed the sheet P without causing double feeding, in relation to the heater temperature shown in FIG. 8, the heater temperature is 60 [° C.], 90 [° C.], and 110 [° C.]. ° C] requires about 40 seconds, about 15 seconds and about 8 seconds of hot air blowing time, respectively.

  Also, if the sheet moisture amount Wp is reduced to 4.2 [%] or less, the present inventor will cause paper wrinkles on the sheet P when fixing the toner image in the fixing device 170 (see FIG. 1). It was found that the quality of the product was reduced. The range of the sheet water amount Wp (Wp ≦ 4.2 [%]) that causes the paper wrinkles of the sheet P is a range R2 shown in FIG. 8 and FIG. 9 described later. More specifically, in the relationship with the heater temperature shown in FIG. 8, when the heater temperature is 60 [° C.], even when the hot air blowing time is longer than 300 seconds, the toner image is fixed at the time of fixing the toner image. No paper wrinkles occur on the sheet P. On the other hand, when the heater temperature is 90 [° C.] and 110 [° C.], when the hot air blowing time is about 170 seconds or more and about 80 seconds or more, paper wrinkles on the sheet P at the time of toner image fixing. Will occur. From this result, when the heater temperature is 60 [° C.], in order to prevent the sheet P from being double-fed and to prevent the quality of the product from deteriorating, the hot air blowing time may be about 40 seconds or more. Further, when the heater temperature is 90 [° C.], in order to prevent the sheet P from being double-fed and to prevent the quality of the product from deteriorating, the hot air blowing time may be about 15 seconds or more and less than 170 seconds. . Further, when the heater temperature is 110 [° C.], the temperature may be about 8 seconds to less than 80 seconds.

  Subsequently, referring to FIG. 9, when the wind speed is changed by changing the rotation speed of fans 611a and 611b (see FIG. 4), how the sheet moisture amount Wp changes with respect to the hot air blowing time. Is explained. Curves C10, C11, and C12 shown in FIG. 9 show transitions of the sheet moisture amount Wp with respect to the hot air blowing time when the wind speed is the slowest, the slowest, and the fastest among the three wind speeds, respectively. ing. It was found that the sheet moisture content Wp eventually converges to the same sheet moisture content in any of the low-speed curve C10, the medium-speed curve C11, and the high-speed curve C12. It was also found that the time required for the sheet moisture content Wp to converge becomes shorter as the wind speed increases.

  However, when the wind speed increases, the behavior of the sheet P becomes unstable, and the contact between the sheet P and the pickup roller 501 (see FIG. 1) is not stable, so that the sheet P is likely to be not fed. Therefore, there is an upper limit of the wind speed at which the non-feed of the sheet P does not occur. The upper limit of the wind speed at which the non-feed of the sheet P does not occur is determined by the type and basis weight of the sheet P. For example, as the basis weight of the sheet P is smaller, the behavior of the sheet P is more likely to be unstable due to the influence of the wind, so it is necessary to reduce the wind speed.

[Relationship between sheet length and hot air blowing time]
In the description, the following (1) to (3) are premised. (1) When a job for feeding k (k is a natural number) sheets is given, immediately before the first highest sheet P is fed from the storage 506 (see FIG. 1). Until the last k-th sheet P is fed, the warm air 24a (see FIG. 4) blows out. (2) The sheet separating ability of the sheets P stacked and stored in the storage 506 is, for example, 20 sheets in a state where the shutter 615a (see FIG. 5A) is fully opened. (3) The speed at which the sheet P is fed and the sheet interval are not changed by the difference in the sheet length of the sheet P.

  First, pay attention to the stacking direction of the fed sheets P. When the above assumptions (1) to (3) are satisfied, the job for feeding the sheets P is received, and all the sheets P from the highest sheet to the lowest sheet stacked and stored in the storage 506 are received. The first to twentieth sheets P are separated by the warm air 24a. Each time one sheet P is fed, the number of sheets from the top is reduced by one, and the sheet P moves to the top. Therefore, when k represents the number of sheets equal to or less than 20, the longest blow of the warm air 24a before the sheet P is fed is the k-th sheet from the top. Further, the sheet P, which was the 21st sheet or later at the start of feeding of the sheet P, is not blown by the warm air 24a at the start of feeding of the sheet P, but is fed after the sheet P itself becomes the 20th sheet. Until then, the air is blown by the warm air 24a. Therefore, when k is 21 or more, the time from the 20th sheet to the kth sheet is the same as the warm air blowing time of the sheet P positioned at the 20th sheet at the start of feeding.

[Shutter operation control]
Next, the operation control of the shutters 615a and 615b will be described. Since the operation of the shutters 615a and 615b is similarly controlled, only the operation control of the shutter 615a will be described below. The shutter 615a is operable in a first mode shown in FIG. 10A and a second mode shown in FIG. 10B. In the first mode, as shown in FIG. 10A, the shutter 615a moves between a closed position A that closes the flow path FP formed by the exhaust duct 617a and an open position B that opens the flow path FP most. To rock. More specifically, the shutter 615a continuously swings in a range from the closed position A to the open position B during the feeding job. Thus, the air coming out of the opening 612a fluctuates, and the sheet P can be efficiently handled. Swing angle of the open position B in the case of the closed position A as a reference (0 °) is an angle theta _1.

That is, the shutter 615a is in the first mode for feeding a common continuous sheet which is a sheet of a first length, swings the angle theta ₁ as the maximum swing angle. Then, at the open position B, the maximum height of the flow path at the adjustment position where the shutter 615a is located is the first height h1.

The shutter 615a swings between the closed position A and the intermediate position C in the two modes, as shown in FIG. The intermediate position C is a position between the closed position A and the open position B. More specifically, the shutter 615a continuously swings in the range from the closed position A to the intermediate position C during the feeding job. Thus, the air coming out of the opening 612a fluctuates, and the sheet P can be efficiently handled. Swing angle of the intermediate position C in the case of the closed position A as a reference (0 °) is an angle theta _2.

That is, the shutter 615a is in the second mode for feeding a long sheet which is longer second length of the sheet than the first length, swings the angle theta ₂ as the maximum swing angle. Then, at the intermediate position C, the maximum height of the flow path at the adjustment position where the shutter 615a is located is a second height h2 smaller than the first height h1 (h2 <h1). As described above, by operating the shutter 615a in the first mode and the second mode, the height of the flow path can be changed, and the height of the air blown to the sheet P stacked on the lift plate 507 can be changed. Can be. For example, in the first mode, among the sheets P stacked on the lift plate 507, air can be blown to the top 20 sheets including the top sheet. In the second mode, among the sheets P stacked on the lift plate 507, air can be blown against the top ten sheets including the top sheet.

[Relationship between hot air blowing time and sheet moisture content]
FIG. 11A is a graph showing a change in the water content of the sheet P along with the progress of the number of sheets fed, and FIG. 11B is a graph showing the water content of the sheet P along the feeding time from the start of feeding. It is a graph showing the amount transition. Note that the sheet moisture content described here is the sheet moisture content Wp at a location where the moisture content is reduced most by blowing hot air.

  Curves C13 and C16 in FIGS. 11A and 11B show the case where the shutters 615a and 615b are operating in the first mode, and the sheet length of the fed sheet P is 30 inches, that is, a long sheet. Is the case. Curves C14 and C17 are obtained when the shutters 615a and 615b are operating in the first mode and the sheet length of the fed sheet P is 19 inches, that is, when the sheet P is a normal length sheet. Curves C15 and C18 are obtained when the shutters 615a and 615b are operating in the second mode and the fed sheet P is a long sheet. All sheets fed along the curves C13 to C18 differ only in size, and have the same sheet type and basis weight.

  Comparing the curves C13 and C14 in FIG. 11A, it can be seen from the degree of progress of the number of sheets fed that the long sheet has a lower rate of water content reduction than the normal sheet. Comparing the curves C16 and C17 in FIG. 11B, it can be seen that if the elapsed time from the start of feeding is the same, the pace of water content reduction does not change so much regardless of the sheet length.

  When the above assumptions (1) to (3) are satisfied, the feeding time of one sheet P is proportional to the sheet length, and thus varies according to the length of the sheet. In addition, the longer the sheet P feeding time, the longer the warm air blowing time for one sheet P. In other words, the warm air blowing time for one sheet P is longer when the fed sheet P is a long sheet than when the fed sheet P is a normal sheet. Referring to the curves C13 and C14 in FIG. 11A, the moisture content of the long sheet is reduced to around 4%, whereas the moisture content of the ordinary sheet is reduced to around 5%. I have. This is because the long blowing time of the warm air 24a received from the time when the lift plate 507 is lifted up and enters the 20 sheets from the top of the sheet bundle to the time when the long sheet is fed is fed. Conceivable.

  Therefore, when a long sheet is fed, an excessive decrease in the sheet water content is more likely to occur than in a case where a normal length sheet is fed, and a product resulting from the excessive decrease in the sheet water amount is obtained. Quality tends to deteriorate. Therefore, in the present embodiment, as described later, the sheet feeding control is performed, and the time for blowing hot air to the sheet P is determined depending on whether the long sheet is fed or the normal sheet is fed. The operation modes of the shutters 615a and 615b are controlled so as to be substantially the same.

  That is, when feeding a normal-size sheet, the shutters 615a and 615b operate in the first mode. In the first mode, since the flow path height at the adjustment position is relatively high, the number of sheets to which the warm air 24a is blown is large, and the sheets can be satisfactorily loosened. On the other hand, when feeding a long sheet, the shutters 615a and 615b operate in the second mode. In the second mode, since the flow path height at the adjustment position is relatively low, the number of sheets to which the hot air 24a is blown is small. As a result, even if the sheet length is long, the total time during which the fed sheet is blown by the warm air 24a can be suppressed, and as shown by curves C15 and C18 in FIGS. An excessive decrease in the amount of water can be prevented. Also, if the number of sheets to which the hot air 24a is blown is small, the sheet separating performance is reduced, but there is no problem in the case of long sheets because the feeding time per sheet is long.

[Sheet feeding control]
Next, the sheet feeding control when the sheet P is fed from the feeding deck 250 will be described with reference to the flowcharts of FIGS. Note that the flowchart shown in FIG. 12 is sheet feeding control when a copy job is input in step S7. As shown in FIG. 12, first, the user operates the display operation unit 310 to select the storage position, type, basis weight, and size of a sheet to be fed (step S1). FIG. 14 illustrates an example of the setting screen 25 displayed on the display operation unit 310. The user selects one of a plurality of sheet attributes displayed on the setting screen 25.

  Next, based on the sheet attribute information selected by the user in step S1, the control unit 700 determines whether the storage position of the fed sheet is the feeding deck 250 (step S2). If the storage position of the fed sheet is not at the feeding deck 250 (step S2: NO), the process ends.

  When the storage position of the fed sheet is the feeding deck 250 (step S2: YES), the control unit 700 uses the environment sensor 614 disposed in the storage 506 to control the temperature and humidity in the storage 506. Is acquired (step S3). Then, the control section 700 determines whether or not the initial loosening process of the sheet bundle by the warm air 24 is necessary based on the acquired environment information and sheet attribute information (step S4).

  When it is determined that the initial loosening process is necessary (Step S4: YES), the initial loosening process is performed (Step S5). Detailed processing in the initial separating process is shown in the flowchart of FIG. As shown in FIG. 13, the control unit 700 determines the heater temperature of the air heater 613 and the outputs of the fans 611a and 611b based on the acquired environment information and sheet attribute information (step S501).

FIG. 15 is a table for setting the heater temperature, and FIG. 16 is a table for setting the fan output. The tables shown in FIGS. 15 and 16 show the heater temperature and the fan output when the type of the sheet P is coated paper and the basis weight is 80 to 150 [g / m ² ], for example. A plurality of tables corresponding to the information may be prepared. These tables are stored in the memory 302.

  In the heater temperature setting table illustrated in FIG. 15, the temperature and the humidity detected by the environment sensor 614 are set in three stages. The air temperature is set in three stages from the lowest one, that is, less than 20 ° C., 20 ° C. or more and less than 30 ° C., and 30 ° C. or more. In addition, the humidity is set in three stages of less than 40 [%], less than 40 [%] and less than 60 [%], and more than 60 [%], respectively, from the lowest.

  The heater temperature of the air heater 613 is set to a higher temperature as the temperature detected by the environment sensor 614 increases and as the humidity increases. When the heater temperature is set to “OFF”, power is not supplied to the air heater 613, so that the temperature of the air heater 613 is approximately equal to the outside air temperature. For example, when the temperature detected by the environment sensor 614 is 20 ° C. or more and less than 30 ° C. as the first temperature, and the humidity is 40% or more and less than 60% as the first humidity, The air heater 613 is set to 60 [° C.] as the first heater temperature. When the air temperature detected by the environment sensor 614 is 30 ° C. or more as the second temperature and the humidity is 60% or more as the second humidity, the air heater 613 is higher than the first heater temperature. The second heater temperature is set to 90 [° C.].

  Similarly, in the fan output setting table illustrated in FIG. 16, the temperature and the humidity detected by the environment sensor 614 are set in three stages. The air temperature is set in three stages from the lowest one, that is, less than 20 ° C., 20 ° C. or more and less than 30 ° C., and 30 ° C. or more. In addition, the humidity is set in three stages of less than 40 [%], less than 40 [%] and less than 60 [%], and more than 60 [%], respectively, from the lowest.

  The fan outputs of the fans 611a and 611b are set to be higher as the temperature detected by the environment sensor 614 becomes higher and the humidity becomes higher. The output of the fans 611a and 611b is changed, for example, by changing the rotation speed of the fans 611a and 611b, that is, the number of rotations per unit time.

  For example, when the temperature detected by the environment sensor 614 is 20 ° C. or more and less than 30 ° C. as a third temperature, and the humidity is 40% or more and less than 60% as a third humidity, The fan output is set to 40 [%] as the first rotation speed. When the temperature detected by the environment sensor 614 is 30 ° C. or more as the fourth temperature and the humidity is 60% or more as the fourth humidity, the fan output is faster than the first rotation speed. The second rotation speed is set to 60 [%].

  After the heater temperature and the fan output are determined in this way, the control section 700 starts blowing the loose air to the sheets P stacked on the lift plate 507 by the air blowing means 620 (step S502). Then, the controller 700 stops blowing the loose air from the air blowing means 620 after waiting for a predetermined time set from the start of blowing the loose air (steps S503 and S504). At this time, the shutters 615a and 615b operate in the first mode. In this way, by blowing the separating air onto the sheet P before feeding the sheet, the suction of the sheets stacked on the lift plate 507 can be eliminated, and the double feeding by the pickup roller 501 can be reduced.

  Next, the control section 700 determines whether or not the fed sheet P is a long sheet (step S505). If the fed sheet P is not a long sheet (step S505: NO), the initial loosening process ends. If the fed sheet P is a long sheet (step S505: YES), the setting screen 125 is displayed on the display operation unit 310 as shown in FIG. 17 (step S506). The setting screen 125 has a “change shutter operation control” button 311 for changing the operation control of the shutters 615a and 615b.

  Then, the control unit 700 receives a change in the shutter operation control from the user (step S507). When the user presses the “change shutter operation control” button 311 (step S507: YES), the control unit 700 changes the shutters 615a and 615b from the first mode to the second mode (step S508), and executes the initial release process. finish. If the user presses the “OK” button 312 without pressing the “change shutter operation control” button 311 (step S507: NO), the control unit 700 does not change the shutters 615a and 615b from the first mode, and performs initial release. End the process.

  When the initial loosening process is completed, as shown in FIG. 12, the control unit 700 permits the start of the job (step S6). When the user sets a sheet on the feeding deck 250 and presses a copy start button to input a copy job (step S7), the control section 700 starts blowing of loose air by the air blowing means 620 (step S8). . Thereafter, the sheet P is fed by the pickup roller 501 after waiting for a predetermined time to elapse as a time until the loosening state is stabilized (steps S9 and S10).

  When the feed sensor 603 detects the trailing end of the last sheet of the job, the control unit 700 determines that it is no longer necessary to loosen the sheet P, and stops the loosening air from the air blowing unit 620 (steps S11 and S12). . Thus, the job and sheet feeding control ends (step S13). The blowing of the loose air by the air blowing means 620 is performed at least before starting the feeding of the first sheet of the job until the feeding of the last sheet of the job is started.

  In the above description of the sheet feeding control, the change of the shutter operation control is received by pressing the “change shutter operation control” button 311 displayed on the display operation unit 310, but is not limited thereto. For example, the control unit 700 acquires sheet attribute information of the sheet P to be fed (see FIG. 1), and automatically receives a change in shutter operation control when the sheet P to be fed is determined to be a long sheet. It may be.

  As described above, when feeding a long sheet, by changing the operation mode of the shutters 615a and 615b to the second mode, the height of the flow path at the adjustment position is reduced, and the sheet to which the hot air 24a is blown is used. Can be reduced. Thereby, even if the sheet length is long, the total time during which the fed sheet is blown with the warm air 24a can be suppressed, and the excessive decrease in the sheet moisture content can be prevented. Therefore, paper wrinkles and transfer omissions can be reduced, and the quality of the product can be improved.

<Second embodiment>
Next, a second embodiment of the present invention will be described. The second embodiment differs from the first embodiment in the content of the initial separating step, but does not substantially differ in points other than the initial separating step. Therefore, in the present embodiment, configurations and processing steps that are not different from those of the first embodiment are omitted from the drawings, or the same reference numerals are given to the drawings, and a description that overlaps with the first embodiment is omitted.

  In the present embodiment, when the operation mode of the shutters 615a and 615b is changed, the influence of the fluctuation of the pressure loss occurring in the flow path is taken into account. For example, when the operation mode of the shutters 615a and 615b is changed from the first mode (see FIG. 10A) to the second mode (see FIG. 10B), the operation mode at the adjustment position in the exhaust ducts 617a and 617b is changed. The channel height becomes smaller. That is, the cross-sectional area of the flow path FP at the adjustment position in the exhaust ducts 617a and 617b is reduced. When the cross-sectional area of the flow path FP at the adjustment position is significantly reduced, the pressure loss of the flow path may increase so as not to be ignored. In this case, the wind speed of the loose air ejected from the openings 612a and 612b is different between the first mode and the second mode, and the performance of loosening the sheet by the loose air may be changed.

  Therefore, as shown in FIG. 18, the initial loosening step in the present embodiment is different from the initial loosening step in the first embodiment in that step S509 is added. In step S509, the control unit 700 changes the output of the fans 611a and 611b according to the operation mode of the shutters 615a and 615b set in step S508. Specifically, when the operation mode of the shutters 615a and 615b is changed from the first mode to the second mode, the outputs of the fans 611a and 611b are larger than before the change. That is, the rotation speed of the fans 611a and 611b is higher when the shutters 615a and 615b operate in the second mode than when the shutters 615a and 615b operate in the first mode. Conversely, when the operation mode of the shutters 615a, 615b is changed from the second mode to the first mode, the outputs of the fans 611a, 611b are smaller than before the change. The rotation speed of the fans 611a and 611b is changed by changing the output of the fans 611a and 611b.

  As described above, before and after the operation mode of the shutters 615a and 615b is changed, it is possible to suppress the fluctuation of the sheet separating performance due to the separating air. Therefore, regardless of the operation mode of the shutters 615a and 615b, the sheet can be satisfactorily released.

  It should be noted that the present invention is not limited to the above-described embodiments as they are, can be implemented in various forms other than the above-described examples, and various omissions and modifications can be made without departing from the gist of the invention. Replacements and changes can be made. For example, the present invention can be applied by appropriately changing the dimensions, materials, shapes, relative arrangements, and the like of the components according to the configuration of the apparatus and various conditions.

  In any of the above-described embodiments, the sheet P stacked on the lift plate 507 is fed by the pickup roller 501, but is not limited to this. For example, the sheet may be suctioned by negative pressure or electrostatic force and fed from the lift plate 507.

  In any of the above-described embodiments, the shutter 615a (see FIG. 5B) swings in the ventilation direction of the warm air 24a to adjust the flow path height h at the adjustment position (see FIG. 5A). Although the example which performs is explained, it is not limited to this. For example, the exhaust ducts 617a and 617b may be configured such that a gate member that can move up and down is attached between the lower end and the upper end of the exhaust ducts 617a and 617b, and the height of the flow path at the position where the gate member is attached can be adjusted. Good. Further, in the above-described embodiment, the example in which the shutters 615a and 615b swing continuously during the job has been described. However, the shutters 615a and 615b do not necessarily need to swing continuously during the job and stop at a predetermined angle. It may be.

  In any of the embodiments described above, an example in which the printer 100 (see FIG. 1) includes the control unit 700 has been described, but the present invention is not limited to this. The control unit 700 may be provided in the image forming system 800, and may be provided in the feeding deck 250, for example.

  In each of the embodiments described above, the example in which the openings 612a and 612b (see FIGS. 3 and 4) are provided in the side regulating plate 610a has been described, but the present invention is not limited to this. The openings 612a and 612b may be provided on the other side regulating plate 610b (see FIG. 4), or may be provided on both of the side regulating plates 610a and 610b. Further, the openings 612a, 612b may be formed in the deck body without providing the side regulating plates 610a, 610b.

  In any of the embodiments described above, an electrophotographic printer 100 has been described as an example of an image forming apparatus. However, an ink jet image forming apparatus that forms an image on a sheet by discharging ink liquid from nozzles is used. Also, the present invention can be applied.

  100: image forming apparatus (printer) / 250: sheet feeding apparatus (feeding deck) / 501: sheet feeding means, roller (pickup roller) / 507: sheet stacking means (lift plate) / 611a, 611b: blower ( Fans / 612a, 612b: Opening / 613: Heater (air heater) / 614: Environmental sensor / 615a, 615b: Adjusting unit, swing member (shutter) / 616a: Swing shaft / 617a, 617b: Duct (exhaust duct) ) / 619: upper surface / 620: air blowing means / 800: image forming system / FP: flow path / h1: first height / h2: second height

Claims (10)

Sheet loading means capable of loading a plurality of sheets,
Sheet feeding means for feeding sheets stacked on the sheet stacking means in a sheet feeding direction,
A blower that blows air by rotating, an opening that blows out the air blown by the blower, a duct that forms a flow path through which air flows between the blower and the opening, and an upper surface of the duct And an adjustment unit that adjusts the height of the flow path at an adjustment position by changing a distance between the sheet stacking unit and the sheet stacking device. Air blowing means for separating a plurality of sheets, including the top sheet, from the top sheet to the bottom sheet loaded on the means,
When the length of the sheets stacked on the sheet stacking unit in the sheet feeding direction is the first length, the adjustment unit may adjust the maximum height of the flow path at the adjustment position to a first height. Operating in a first mode that is adjusted so that the length in the sheet feeding direction of the sheets stacked on the sheet stacking means is a second length longer than the first length. Operating in a second mode in which the maximum height of the flow path at the adjustment position is adjusted to a second height smaller than the first height;
A sheet feeding device, characterized in that: The blower has a higher rotation speed when the adjusting unit operates in the second mode than when the adjusting unit operates in the first mode.
The sheet feeding device according to claim 1, wherein: The adjusting section is disposed in the flow path, and has a swinging member that adjusts the height of the flow path at the adjustment position by swinging the upper end side about a swing axis on the lower end side,
The sheet feeding device according to claim 1, wherein The swing member continuously swings during a feeding job in which the sheet feeding unit feeds a sheet,
The maximum swing angle of the swing member is an angle at which the height of the flow path at the adjustment position becomes the first height when operating in the first mode, and operates in the second mode. In this case, an angle at which the height of the flow path at the adjustment position becomes the second height,
The sheet feeding device according to claim 3, wherein: The sheet feeding unit is a roller that contacts the top sheet stacked on the sheet stacking unit and feeds the top sheet by rotating,
The opening is disposed so as to overlap with a contact portion where the roller and the uppermost sheet abut on each other when viewed in a width direction orthogonal to the sheet feeding direction.
The sheet feeding device according to any one of claims 1 to 4, wherein: A heater for raising the temperature of air blown out from the opening,
The sheet feeding device according to any one of claims 1 to 5, wherein: An environmental sensor that detects an environmental state including a temperature and a humidity of an atmosphere around a sheet stacked on the sheet stacking unit,
When the temperature and the humidity detected by the environment sensor are the first temperature and the first humidity, respectively, the heater is set to the first heater temperature, and the temperature and the humidity detected by the environment sensor are the same. If the second temperature is higher than the first temperature and the second humidity is higher than the first humidity, the second heater temperature is set to be higher than the first heater temperature.
The sheet feeding device according to claim 6, wherein: An environmental sensor that detects an environmental state including a temperature and a humidity of an atmosphere around a sheet stacked on the sheet stacking unit,
When the temperature and the humidity detected by the environment sensor are a third temperature and a third humidity, respectively, the blower rotates at a first rotation speed, and the temperature and the humidity detected by the environment sensor are respectively the same. When the fourth temperature is higher than the third temperature and the fourth humidity is higher than the third humidity, the motor rotates at a second rotation speed higher than the first rotation speed.
The sheet feeding device according to any one of claims 1 to 7, wherein: When the sheet feeding unit feeds a sheet according to a feeding job, the air blowing unit starts feeding the last sheet of the feeding job before starting feeding of the sheets stacked on the sheet stacking unit. Until feeding is started, continue blowing air from the opening,
The sheet feeding device according to any one of claims 1 to 8, wherein: A sheet feeding device according to any one of claims 1 to 9,
And an image forming apparatus that forms an image on a sheet fed from the sheet feeding apparatus.
An image forming system, characterized in that:

Images