JP2001031273A - Sheet supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply a sheet in a stable state regardless of a kind of sheet by arranging an air blowing means for blowing air against the sheet housed in a sheet housing means, and controlling the air blowing means on the basis of a designating result by a sheet kind designating means. SOLUTION: This sheet supply device is provided with a sheet housing means 1 for housing a sheet P, a sheet supply means 2 for supplying the sheet P from the sheet housing means 1 and an air blowing means 3 for blowing air against the sheet P housed in the sheet housing means 1. The air blowing means 3 controls ON/OFF of, for example, air blowing by a control means 5. A sheet kind designating means 4 is arranged in the sheet supply device to practice control by the control means 5 on the basis of the designating information. The sheet kind designating means 4 is provided with a paper kind selecting switch 6 for designating a kind of sheet P to designate glossy paper such as coating paper and plain paper by switching the paper kind selecting switch 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus for feeding stacked sheets, and more particularly to a sheet feeding apparatus for separating and feeding sheets having high adhesion between sheets.

[0002]

2. Description of the Related Art In an image forming apparatus such as a printer or a copying machine, a cut sheet that enables continuous paper feeding is generally used as a medium on which an image is formed. Conventionally, plain paper or high-quality paper designated by a copier maker has been used. Since these sheets have low surface smoothness, the adhesion between the sheets is low, and even when the sheets are fed out one by one from a sheet stacking unit such as a paper feed tray,
It was relatively easy to prevent double feeding in which a plurality of sheets were supplied in close contact. However, in recent years, with the diversification of recording media, transport of various types of sheets, including those with high surface smoothness, has been required, and in particular, whiteness has increased with the development of color technology. There is a growing demand for the same model to transport glossy paper such as coated paper, film sheets, tracing paper, etc., which have been made glossy. Such coated paper, glossy paper such as film sheet, tracing paper, etc., has a strong adhesion between the sheets, so it is difficult to prevent double feeding, and special measures are required for sheet supply.

For example, the coated paper will be described as an example. As the quality of the coated paper increases, the amount of coating increases and the white gloss, which is an optical property, increases. The degree increases. On the other hand, when the surface smoothness increases, the gap between the papers when they come into contact with each other becomes narrower, the air pressure does not pass through the gap, and the generated negative pressure is maintained, and the adhesion between the sheets (between the papers) is reduced. Become stronger. In particular, when a smooth sheet such as a coated paper is stacked in a high humidity environment, the sheets adhere to each other and the degree of adhesion is further increased. Film sheets and tracing paper also have high surface smoothness and high sheet-to-sheet adhesion.

[0004] When feeding out such smooth sheets having strong adhesion between sheets one by one from a sheet feeding tray on which the sheets are stacked, the sheets are separated one by one using a normal plain paper feeding apparatus. It becomes very difficult to transport. In particular, a sheet feeding device using a draw-in roll that rotates by contacting the surface of the sheet with a predetermined pressing force to draw the sheet, and a method in which a supply roll and a separation roll are pressed and separated at a constant pressure when the sheet is separated. In this case, when the smooth sheet is separated and conveyed, the pressing force is required to be about 30 times as large as that of the ordinary plain paper. As a method of eliminating such close contact with a smooth sheet in advance, the present applicant has disclosed Japanese Patent Application Laid-Open No. H11-5643.
Discloses a technique for blowing air from the side of a stacked sheet. According to such a technique, a great effect can be achieved in eliminating the adhesion force in the smooth sheet.

[0005]

The technique of feeding air after blowing air from the side of the paper to release the adhesion can significantly improve the smooth sheet conveyance performance, as described in Japanese Patent Application Laid-Open No. H11-5643. According to the technology disclosed in the publication, air is blown regardless of the type of sheet. Therefore, when feeding plain paper that does not require air blowing, wasteful energy is consumed, which is not preferable.

On the other hand, glossy paper such as coated paper has a coefficient of friction between sheets of about 0.3, whereas plain paper has a high coefficient of friction between sheets and a coefficient of friction of 0.5 to 0.8. Becomes Therefore, when air is blown against plain paper, the resistance between the sheets is eliminated in the gap between the sheets.For example, when the sheet is supplied by a friction roll such as a draw-in roll (pickup roll), the sheet is not supplied. Paper speed increases rapidly. As a result, a plurality of sheets rush into the downstream sheet separating section at a high speed, and the sheets are not sufficiently separated and conveyed as a double feed.

[0007]

In order to solve the above-mentioned technical problems, a sheet feeding apparatus according to the present invention comprises a sheet storing means 1 for storing a sheet P, as shown in FIG. A sheet supply unit 2 for supplying the sheet P from 1; an air blowing unit 3 for blowing air to the sheet P stored in the sheet storage unit 1; a sheet type specifying unit 4 for specifying the type of the sheet P; A control unit 5 for controlling air blowing by the air blowing unit 3 based on the specification result by the sheet type specifying unit 4 is provided.

The sheet type designation means 4 designates whether or not the sheet stored in the sheet storage means 1 is glossy paper, and the air blowing means 3 designates glossy paper by the sheet type designation means 4. Therefore, air blowing can be performed on sheets P such as plain paper that do not require air blowing, and air can be stopped on sheets P that do not require air blowing. Is preferable because a secondary obstacle caused by spraying can be prevented beforehand. here,
The glossy paper designated by the sheet type designation means 4 includes a coated paper, a film sheet, a tracing paper, etc.
It is distinguished from plain paper.

The sheet type designating means 4 is characterized in that the user designates the sheet type using the paper type selection switch 6, so that the sheet supply device can control the air blowing according to the type of the sheet P. The sheet P can be supplied in a stable state. As the type of the sheet P, in addition to paper types such as coated paper, film, and plain paper, the surface state of the sheet (slippery or rough), the basis weight of the sheet, thickness information such as thick paper or thin paper, etc. It is possible to configure so that selection can be made with arbitrary contents. Also,
If a switch based on a touch sensor provided on the liquid crystal display panel is employed as the paper type selection switch 6 in addition to a switch using a button or the like, the paper type can be selected by switching the display, and the space for the control panel can be reduced. It is preferable because it can be reduced.

Further, when the sheet feeding apparatus is a printer, for example, an image forming apparatus, the sheet type specifying means 4 specifies the type of the sheet P by a user from a personal computer or the like connected by a cable such as a net. , The type of the sheet P can be designated. In such a case, the sheet type designating means 4 of the sheet feeding apparatus in the present invention is not necessarily limited to a hardware configuration such as a switch, but corresponds to a configuration for recognizing instruction information from a personal computer or the like.

Furthermore, if the control of the air blowing means 3 by the control means 5 controls ON / OFF of the air blowing based on the designation by the sheet type designating means 4, the control of the air blowing means 3 can be performed for a necessary type of sheet. This is preferable because air can be blown only when the air is blown. If the air blowing means 3 uses a fan driven by the rotation of a motor, the ON / OFF control of the air blowing is provided in the air blowing means 3 in addition to the ON / OFF control of the motor. It is also possible to switch on / off the spraying by switching the shutter of the duct. The control of the air blowing means 3 by the control means 5 is not limited to ON / OFF of the air blowing,
This includes various controls related to air blowing, such as controlling the amount of air, controlling the blowing angle and direction, controlling the temperature and humidity conditions of the air flow, and controlling the time interval of intermittent blowing. Can be.

The sheet supply device of the present invention includes a sheet storage unit 1 for storing a sheet P, a sheet supply unit 2 for supplying the sheet P from the sheet storage unit 1, and a sheet storage unit 1 for storing the sheet P. Air blowing means 3 for blowing air to the sheet P, wherein the air blowing means 3 performs air blowing on the sheet P having a low coefficient of friction between sheets, and performs air blowing on the sheet P having a high coefficient of friction between sheets. In addition, if air blowing is not performed, the close contact of the sheet P can be eliminated by air blowing, and the trouble of increasing the sheet supply speed due to air blowing for the sheet P having a high coefficient of friction between sheets can be prevented. It is possible to do.

Next, the operation of the above technical means will be described. An air blowing unit 3 for blowing air to the sheets P stacked on the sheet storage unit 1 is provided. The air blowing unit 3 is controlled by a control unit 5.
For example, ON / OFF of air blowing is controlled. Further, the sheet feeding apparatus is provided with a sheet type specifying means 4 on a control panel or the like on the outer wall of the apparatus, for example, and control by the control means 5 is executed based on the specification information of the sheet type specifying means 4. The sheet type specifying means 4 is provided with a paper type selection switch 6 for specifying the type of the sheet P, and the user of the sheet feeding apparatus switches the paper type selection switch 6 to perform, for example, a coating operation. It is possible to specify glossy paper such as paper and plain paper.

For example, when the coated paper is selected by the paper type selection switch 6, the control means 5 receives the information and starts the operation of the air blowing means 3 to load the paper loaded on the sheet storage means 1. For example, air is blown from the side of the sheet P. On the other hand, when plain paper is selected by the paper type selection switch 6, the control means 5 receives this information and prohibits the operation of the air blowing means 3;
Do not spray air. By such a switching operation by the control means 5, air can be blown only to the sheet P having a high degree of closeness between sheets, and optimal sheet supply according to the type of the sheet P can be performed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings. FIG.
1 shows an embodiment of an image forming apparatus to which the present invention is applied. In FIG. 1, an image forming apparatus 21 serving as a sheet feeding apparatus includes an image reading apparatus (I
A receiving unit 29 connected to an external device 25 such as an IT) 23 and a personal computer (PC) via a communication line 27, and controls the image writing device 31 based on image information from the receiving unit 29. Image recording control unit 33
Is provided. The image recording controller 33 controls the sheet supply unit 60, the air blower 71, and other sheet conveyance systems, which will be described later, in addition to the control of the image writing device 31. Further, the image forming device 21 includes an image carrier 3 on which an electrostatic latent image is written by the image writing device 31.
5, a charger 37 disposed along the circumferential direction of the image carrier 35 to charge the image carrier 35, and a developing device 39 for developing the charged image carrier 35 with toner. The toner image on the image carrier 35 is transferred to the sheet conveyed by the transfer roller 43. Further, a fixing device 45 for fixing the image transferred to the sheet, a discharge roller 47 for discharging the fixed sheet, a discharge tray 49 for stacking the sheet discharged by the discharge roller 47, and a discharge tray 49 not used for transfer. And a cleaner 41 for collecting surplus toner. Further, a control panel (operation panel) 100 that enables various operations by the user of the image forming apparatus 21 is provided on an outer wall of the image forming apparatus 21 according to the present embodiment.

Further, the image forming apparatus 21 is provided with a plurality (four in the present embodiment) of sheet supply trays 59 for storing sheets by size or sheet feeding direction, and these are provided in upper and lower stages. The sheet supply tray 59 is configured such that a bottom plate (not shown) provided therein is moved up and down by driving a motor (not shown). A sheet supply unit 60 is provided above the sheet supply tray 59, and separates and conveys the sheet by contacting the upper surface of the sheet lifted by the bottom plate. The sheet is conveyed to an image forming unit including the carrier 35 and the like. Further, each sheet supply tray 59 is provided with an air blowing device 71 for blowing air so as to face the side surface of the sheet.

FIG. 3 is a perspective view showing the sheet supply unit 60. The sheet supply unit 60 has a draw-in roll that frictionally contacts the upper surface of the stacked sheets P and sequentially feeds out the sheets P.
(Pickup roll) 61, a conveying roll (feed roll) 62 that separates the sheet P fed from the drawing roll 61 and conveys the sheet P toward the downstream portion, and separates the sheets P one by one while being pressed by the conveying roll 62. A separating roll (retard roll) 63 is provided. Here, the pull-in roll 61, the transport roll 62, and the separating roll 63 are
It is composed of rolls of the same shape and size,
The sheet P is transported by frictional contact with the sheet P. This transport roll 6
2 is driven by receiving power from a not-shown feed motor via a not-shown drive gear and a feed clutch. On the other hand, the draw-in roll 61 is
The rotation of the transport roller 62 is performed by gears 82 in association with the drive of the transport roll 62. Further, the pull-in roll 61 operates the solenoid 83 that operates in response to a drive signal from the image recording control unit 33 to operate the sheet P via the link 84.
The sheet P can be fed out by dropping onto the upper surface of the sheet P and rotating and driving the sheet P with a predetermined pressing force. The movement of the arm 81 is detected by the photo sensor 85, and is controlled so that the height of the sheet P falls within a certain range. Further, the separating roll 63 is brought into contact with the transport roll 62 with a weak pressure by a spring 89 via a support 88 about a pivot 87 as a rotation center. Further, the separating roll 63 is connected to a rotating first gear 91 and a fixed second gear 92 via a torque limiter 90 provided on a shaft 63a.

FIG. 4 is a plan view of the sheet supply tray 59. An end guide 65 for regulating the rear end face of the sheet P in the sheet feeding direction is provided upstream of the sheet supply tray 59 in the sheet feeding direction.
Is provided, and a side fixed guide 67 is provided on a side surface in a direction perpendicular to the sheet feeding direction, and a movable side guide 6 configured to be movable depending on the size of the sheet P is provided at a position facing the fixed guide 67.
9 are provided. An air blowing device 71 is provided in the vicinity of the fixed side guide 67, and air is blown to the sheet P through an air outlet 73 provided in the fixed side guide 67. The air blowing device 71 is provided with a FAN that rotates in the direction of the arrow in the drawing, and is configured to supply high-pressure air.

FIG. 5 is a schematic explanatory view showing the sheet supply tray 59 from the side. As described above, the drawing roll 61 in the sheet supply unit 60 is connected to the sheet supply tray 59.
In contact with the upper surface of the sheets P stacked on the sheet P, and acts to sequentially feed out the sheets P. Further, the sheet P fed out from the pull-in roll 61 passes through a separating section constituted by the transport roll 62 and the separating roll 63, and the sheet P
Even if more than one sheet is fed out, they are conveyed to the downstream side in a state where they are separated one by one. In the case of transporting ordinary plain paper or copy paper, the contact pressure of the draw-in roll 61 on the upper surface of the paper is set to about 100 gf, and the retard pressure between the transport roll 62 and the separating roll 63 is set to 4 g during transport.
It is set to be about 00 gf.

Coated paper having a high adhesion between sheets in such a setting state (a composite sheet in which a coating color which is a kind of paint is applied to both sides or one side of the sheet P for the purpose of improving printability) or When trying to convey a film sheet or the like, a plurality of sheets P are conveyed collectively and conveyed to the downstream side as a double feed. At this time, if the coated paper or film sheet is simply handled by simply increasing the contact pressure, an extremely high contact pressure is required with respect to the contact pressure with general plain paper or copy paper. Clarified in the experiment. Therefore, in the present embodiment, an air blowing device 71 is provided as one of the adhesion canceling means for the sheet P having high adhesion such as coated paper, and the high-pressure air is blown on the sheet P to thereby make the sheet P close to the sheet P. , And the sheet P can be supplied without increasing the contact pressure of each roll. More specifically, the lower end of the opening of the air outlet 73 of the air blowing device 71 shown in FIG. 4 is lower than the uppermost sheet P loaded, and the upper end of the opening is higher than the uppermost sheet P. It is configured as follows. For example, by intermittently blowing air from the air outlet 73, a lift as shown by an arrow in FIG. 5 acts on the sheets P, and the sheets P are separated one by one. By driving the draw-in roll 61 in this state, the sheet P is fed out almost every sheet, and is conveyed downstream in a stable state.

Next, the configuration of the control panel (operation panel) 100 in the present embodiment will be described with reference to FIGS.
This will be described with reference to FIG. As shown in FIG. 6, the control panel 100 includes a lamp 101, a display 102, and keys 103. The lamp 101 turns on and off the state of the image forming apparatus 21 which is, for example, a printer.
Flashing and off. The display 102
Is a liquid crystal display (LCD), which displays the contents specified by the key 103. The key 103 is
A mode key for designating a mode such as ART or 201H;
A menu key for specifying paper size, magnification setting, font, etc., and a pause key for instructing a pause state such as canceling / discharging all jobs in the printer are provided.
It has up, down, left, and right keys for moving menu items.

By operating the menu key of the key 103, the sheet supply tray 59 of the image forming apparatus 21 is operated.
When the display 102 enters a state in which the type of sheet supplied is designated, as shown in FIG. 6, the display 102 is configured to display a sheet type name composed of coated paper, film, tracing paper, and plain paper. Is done. Since the sheet type name is used relatively frequently as a sheet supply in the image forming apparatus 21 and has a relatively large influence of the air ON / OFF at the time of air blowing, this sheet type name is used in the present embodiment. In the form, it is configured such that it can be displayed on behalf of other types. The user selects the type of the sheet P from the sheet type names displayed on the display 102 by pressing the up / down / left / right keys of the key 103, and further presses the ejection / setting key of the key 103. , The type of the sheet P can be designated.

When the key 103 is pressed by the user, the image recording control unit 33 recognizes the type of the sheet P supplied from the sheet supply tray 59. When the sheet P is recognized to be glossy paper such as coated paper, film paper, tracing paper, etc., the image recording control unit 33 blows out the air before a predetermined time before the supply of the sheet P from the sheet supply unit 60 is started. It controls to drive the motor of the device 71. The air blowing device 71 driven by the motor in response to the instruction from the image recording control unit 33 blows air from the air blowing port 73 toward the side surface of the sheet P.
Since the upper end of the air outlet 73 is higher than the upper surface of the stacked sheets P and the lower end of the air outlet 73 is lower than the upper surface of the stacked sheets P, as shown in FIG. Is pulled up by the draw-in roll 61 in a state where the glossy paper has a high adhesiveness and is separated one by one, and is conveyed further downstream in a stable state.

On the other hand, when plain paper is selected on the control panel 100 of FIG.
It is determined that the air blowing from the air blowing device 71 is not required, and the air blowing operation on the sheet P is prohibited. As a result, the sheet P made of plain paper is drawn in by the draw-in roll 61 based on a feed signal from the image recording control unit 33 and is conveyed downstream without air blowing. That is, when the sheet P is plain paper, the plain paper has a relatively low coefficient of friction due to a relatively high coefficient of friction between sheets, does not require separation by air blowing, and is stable without air blowing. Paper can be fed. On the other hand, when air is blown on the plain paper, the resistance between the papers is lost, and the paper feeding speed from the draw-in roll 61 rapidly increases. In this state, when a plurality of sheets P enter the nip portion between the transport roll 62 and the separation roll 63, the sheet P passes through the sheet supply unit 60 without being sufficiently separated because the sheet feeding speed is high. As a result, it is transported to the downstream side as a double feed.
According to the present embodiment, when plain paper having a relatively high coefficient of friction between sheets is conveyed, control is performed so that air blowing is not performed on the stacked sheets P. This can be prevented beforehand, and stable sheet supply can be realized.

FIGS. 7A and 7B show the control panel 1.
13 shows another display mode at 00. The paper type switch 105 in FIG. 7A can select between slippery paper and rough paper by a lever type changeover switch 106. Such a lever type changeover switch can also be used when selecting a paper type such as coated paper shown in FIG. This switch 10
When the smooth paper is selected in step 6, the sheet P whose surface is smooth has a high degree of close contact between the sheets.
The control unit 3 controls the air blowing device 71 to drive the motor a predetermined time before the supply of the sheet P from the sheet supply unit 60 is started. On the other hand, when the rough paper is selected by the switch 106, it is determined that air blowing is not necessary because the rough surface of the sheet P has a low degree of close contact between the sheets, and the air blowing device is determined by the image recording control unit 33. No signal to drive 71 is issued.

The paper type switch 10 shown in FIG.
Reference numeral 7 allows the user to select the basis weight, which is the unit weight of the sheet P, using the button type switch 108. This button-type switch can also be used when selecting the paper type such as the coated paper shown in FIG. 6 or when specifying the surface state of the sheet P as shown in FIG. This switch 1
Based on the basis weight selected in step 08, the image recording control unit 33 controls the air blowing device 71. For example, if the air volume can be adjusted by the air blowing device 71, the air volume is reduced when the basis weight of 120 gsm or less as thin paper is specified, and the air volume is reduced when the basis weight of 200 gsm or more as thick paper is specified. And so on. When the air outlet 73 has a plurality of nozzles having different shapes, it is possible to perform control so that the nozzle shape is changed between thin paper and thick paper. More specifically, because thick paper is difficult to levitate with air, it is configured to increase the air volume by narrowing the nozzle shape, and in view of the fact that two or more sheets of thin paper often float together, In such a state, the upper end of the nozzle is widely opened so as to continue the air blowing. As described above, in the present embodiment, in addition to the mode in which the air blowing from the air blowing device 71 is simply turned ON / OFF, it is possible to adjust the air volume, switch the nozzle shape, and the like.

As described above, according to the present embodiment, coated paper is provided by a touch sensor for a liquid crystal display panel or the like provided on the control panel 100, a lever type switch, a button type switch, or the like. It is possible to input various types of information such as paper type, sheet surface condition, sheet basis weight, etc., and various types of information such as ON / OFF of the air blowing device 71, air volume, nozzle shape switching, etc. based on the input. Control can be performed. As a result, air can be blown in an optimal state according to different types of sheets P, so that stable supply can be realized regardless of the types of sheets P.

In this embodiment, the image forming apparatus 21
In the above, the configuration in which the type information of the sheet P is input from the control panel 100 provided on the outer wall of the apparatus body has been mainly described, but the present embodiment is not limited to this mode. For example, when the image forming apparatus 21 is used as a printer, as shown in FIG.
It is also possible to input the type of various sheets P from an external device 25 such as a connected personal computer (PC), and the input information is received by the receiving unit 29 via the communication line 27 together with the image information, and The recording control unit 33 can also control the air blowing device 71 based on the input information. In this case, the external device 25 will have designation software (a printer driver or the like) equivalent to a mode for designating the type of the sheet P provided on the control panel 100 described above.

[0029]

As described above, according to the present invention,
Air blowing can be controlled based on sheet information specified by the user, and sheets can be supplied in a stable state regardless of the type of sheet.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an outline of an apparatus according to the present invention.

FIG. 2 is an explanatory diagram illustrating an outline of an image forming apparatus according to an embodiment.

FIG. 3 is a perspective view illustrating a sheet supply unit according to the embodiment.

FIG. 4 is a plan view of a sheet supply tray according to the embodiment.

FIG. 5 is a schematic explanatory view showing a sheet supply tray in the present embodiment from the side.

FIG. 6 is an explanatory diagram illustrating a control panel according to the present embodiment.

FIGS. 7A and 7B are explanatory views illustrating another display mode of the control panel according to the present embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sheet accommodation means, 2 ... Sheet supply means, 3 ... Air blowing means, 4 ... Sheet type designation means, 5 ... Control means, 6 ... Paper type selection switch, 21 ... Image forming apparatus, 25
... External equipment, 27 ... Communication line, 29 ... Receiving unit, 31 ... Image writing device, 33 ... Image recording control unit, 35 ... Image carrier
37: charger, 39: developing device, 43: transfer roller, 4
5: fixing device, 59: sheet supply tray, 60: sheet supply section, 61: pull-in roll, 62: transport roll, 63 ...
Separating roll, 65: End guide, 67: Side fixed guide, 69: Side movable guide, 71: Air blowing device, 73: Air outlet, 100: Control panel, 101: Lamp, 102: Display, 103 ...
Key, 105: paper type switch, 106: switch, 10
7: paper type switch, 108: switch, P: sheet (paper).

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masahiro Oizumi 2274 Hongo, Fuji Xerox Co., Ltd., Ebina City, Kanagawa Prefecture Reference) 3F343 FA02 FB02 FC01 GA01 GB01 GC01 GD01 HA12 HB01 JD03 JD28 MB03 MB09 MC13 MC21

Claims (4)

[Claims] A sheet accommodating means for accommodating a sheet; a sheet supply means for supplying a sheet from the sheet accommodating means; an air blowing means for blowing air to the sheet accommodated in the sheet accommodating means; A sheet feeding apparatus comprising: sheet type specifying means for specifying a type; and control means for controlling air blowing by the air blowing means based on a specification result by the sheet type specifying means. 2. The method according to claim 1, wherein the sheet type designation unit designates whether or not the sheet accommodated in the sheet accommodation unit is glossy paper, and the air blowing unit designates glossy paper by the sheet type designation unit. 2. The sheet feeding apparatus according to claim 1, wherein the air is blown by the apparatus. 3. A sheet feeding apparatus according to claim 1, wherein said sheet type designation means is designated by a user using a paper type selection switch. 4. A sheet storing means for storing a sheet, a sheet supplying means for supplying a sheet from the sheet storing means, and an air blowing means for blowing air to the sheet stored in the sheet storing means, The sheet feeding device according to claim 1, wherein the air blowing means performs air blowing on a sheet having a low coefficient of friction between sheets, and does not perform air blowing on a sheet having a high coefficient of friction between sheets.