JP2000351462A - Sheet feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a sheet conveying failure caused by the advance of a sheet floated by air blow during standby as well as to eliminate tight fixing of the sheet by flowing air when the sheet is not fed, for example, during standby. SOLUTION: This sheet feeding device is provided with a sheet housing means 1 for housing sheets P, a sheet drawing-in means 2 to be operated toward the sheets P when feeding the sheets P from the sheet housing means 1 and for drawing in the sheets P while being in contact with the upper surface of the sheet P, an air blowing means 3 for blowing air to the end surface of the sheets P housed in the sheet housing means 1 during standby in which the sheet P is not fed from the sheet housing means 1 by the sheet drawing-in means 2, and an advance regulating means 4 for regulating the advance of the sheet P while air is blown by the air blowing means 3 during standby.

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 image forming apparatuses such as printers and copiers, cut sheets that enable continuous paper feeding are generally used as a medium on which an image is formed. , Plain paper and high-quality paper specified by the copier manufacturer were used. Since these sheets have low surface smoothness, the sheet-to-sheet adhesion is low, and even when the sheets are fed one by one from a sheet stacking unit such as a sheet feed tray, a multi-feed in which a plurality of sheets are fed in close contact with each other. Was relatively easy to prevent. 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 addition to OHP sheets, cardboard, tracing paper, etc., particularly With the development of color technology, there has been an increasing demand for using a coated paper having a coating color applied to the surface of a paper in order to increase whiteness, increase gloss, and reduce printing unevenness.

[0003] In this coated paper, as the amount of coating decreases, the influence of irregularities on the surface of the base paper becomes more pronounced, causing unevenness in the surface structure leading to uneven printing.
The higher the quality, the higher the coating amount, the higher the white gloss, which is an optical property, and the higher the quality, the higher the surface smoothness. On the other hand, when the surface smoothness increases, the gap between the papers when they come into contact with each other becomes narrower, and the negative pressure generated due to a state in which air does not pass through the gap is maintained.
(Between papers) becomes stronger. In particular, when a smooth sheet having a smooth surface such as a coated paper is stacked under a high humidity environment, the sheets are attracted to each other and the degree of adhesion becomes higher.

When a smooth sheet such as a coated paper having a strong adhesion between papers is fed out one by one from a paper feed tray on which the sheets are stacked, an ordinary apparatus for feeding plain paper is used. In such a case, it is very difficult to separate and transport each sheet. 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 in
Japanese Patent Application Publication No. 5643/1999 proposes a technique for blowing air from the side of a sheet. According to such a technique, a great effect can be achieved in eliminating the close contact of the smooth sheet.

[0005]

As described above, it is possible to remarkably improve the transport performance of the smooth sheet by the technique of blowing the air from the side of the sheet to release the close contact, and then feeding the sheet. In order to solve the problem, it is necessary to continuously perform air blowing for a predetermined time from the start of air blowing. At this time, when the sheet feeding operation is not performed, the pull-in roll 2 separates from the sheet surface and presses the sheet surface during sheet feeding.
When 01 is adopted, as shown in FIG. 8, by blowing before the sheet feeding operation from the air blowing means 202,
The loading posture of the stored sheets P is disturbed. In particular,
If air is blown for a long time before the paper feeding operation in order to properly separate the strongly adhered smooth sheets, the resistance between the sheets will be extremely reduced, and the stacking posture of the sheets will be greatly disturbed. They are conveyed collectively to the downstream part, and so-called double feed is induced.

Therefore, the object of the present invention is to
An object of the present invention is to eliminate the adhesion of sheets by blowing air during standby, for example, when a sheet is not supplied, and to prevent sheet conveyance failure due to advancing of a floating sheet caused by blowing air during standby.

[0007]

That is, as shown in FIG. 1, a sheet feeding device according to the present invention comprises a sheet storing device 1 for storing a sheet P, and a sheet feeding device for supplying the sheet P from the sheet storing device 1. Sometimes it works towards seat P,
A sheet retraction unit 2 that contacts the upper surface of the sheet P and retracts the sheet P; and a sheet P stored in the sheet storage unit 1 during standby when the sheet P is not supplied from the sheet storage unit 1 by the sheet retraction unit 2. It is characterized by comprising air blowing means 3 for blowing air to the end face, and advance regulating means 4 for regulating the advance of the sheet P while air is being blown by the air blowing means 3 during standby.

In such technical means, the air blowing timing by the air blowing means 3 is as follows.
It is preferable that air be blown for a predetermined time after the sheet storage unit 1 is set in the apparatus main body, since the close contact of the sheet P can be released before the actual sheet feeding operation. In particular, when the sheet retraction unit 2 that separates from the sheet P when the sheet P is not supplied is adopted,
When air is blown before the actual sheet feeding operation, the sheet P is completely in a free state. Therefore, the significance of the problem solving means in the present invention is great.

Further, as the advance restricting means 4, if the sheet advance can be prevented before the actual sheet feeding operation by the sheet retracting means 2, for example, a method of opening and closing a gate, a method of pressing a trailing end of the sheet, and the like. The sheet P accommodated in the sheet accommodating means 1 can be arbitrarily adopted.
Is characterized in that the forward movement of the sheet P is restricted by pressing the sheet P from the upper surface, which is advantageous in that the disturbance at the leading end of the sheet P can be reliably prevented. As a driving method for pressing from the upper surface, a solenoid 6, a motor (not shown), or the like can be arbitrarily selected.

Further, if the advance regulating means 4 is disposed so as to be in contact with the vicinity of the end of the sheet P, it is possible to prevent the sheet stacking posture from being disturbed without adversely affecting the action of the air blowing means 3 for eliminating the close contact. It is preferable because it can be done. The vicinity of this end can be selected near the four corners of the sheet P, near the ends of the four sides, and the like, and the pressing location can be selected arbitrarily at one or a plurality of locations. When the air blowing means for blowing is adopted, it is preferable to use several places at the leading end or the trailing end in the sheet feeding direction of the sheet P from the viewpoint that the contact releasing action can be effectively utilized.
It should be noted that the sheet pull-in means 2 may be used as the advance restricting means by acting in accordance with the timing of air blowing by the air blowing means 3 irrespective of the sheet supply.

Here, the standby state in which the sheet is not supplied means that the air is periodically blown to the sheet P, and that the operator loads the sheet P in the sheet storage means 1 and sets the sheet P in the apparatus main body. This includes the predetermined timing after the replenishment of the sheets, the predetermined timing after the power of the apparatus body is turned on, and the like. Particularly, at the predetermined timing after the replenishment of the sheets, it is expected that the degree of adhesion between the stacked sheets is high. Therefore, it is particularly effective for eliminating adhesion by blowing air. Further, in the present invention, it is sufficient that air is blown at least at the standby time when the sheet P is not supplied.

Further, the sheet feeding apparatus of the present invention includes a sheet storing means 1 for storing a sheet P, a sheet P which is brought into contact with the upper surface of the sheet P when the sheet is supplied from the sheet storing means 1, Sheet supply means 2 which is separated from the upper surface of the sheet when the sheet P is not supplied, and the sheet P
Air blowing means 3 for blowing air to the end face of the sheet P stored in the sheet storing means 1 at the time of standby when no air is supplied, and sheet pull-in while air is blown by the air blowing means 3 at the time of standby. A control means 5 for controlling the means 2 to contact the upper surface of the sheet so as to restrict the advance of the sheet P is provided.

It is preferable that the control means 5 in this technical means press the sheet drawing means 2 against the upper surface of the sheet P at the timing when the air blowing means 3 blows air. That is, irrespective of the sheet supply, if the sheet P is controlled so as to press the upper surface of the sheet P without rotating the sheet retraction unit 2, the sheet P can be regulated without restricting the advance of the sheet P without providing a special mechanism. In that it is possible to prevent the loading posture from being disturbed.

Next, the operation of the above technical means will be described. After an operator (user) stores the sheet P in the sheet storing unit 1 and sets the sheet storing unit 1 in the apparatus main body, for a predetermined time, that is, in one mode at the time of standby, the air blowing unit 3 operates the sheet storing unit 1. Is blown from the side of the sheet P (the side in the conveyance direction) of the sheet P stacked on the sheet. The sheet retraction unit 2 that contacts the upper surface of the sheet P and conveys the sheet P is in contact with the upper surface of the sheet P when the sheet P is actually conveyed, and rotates for a predetermined time to thereby rotate the sheet P at a downstream portion thereof. 7, the sheet P is conveyed. Therefore, in the standby state, the sheet P is not pressed, and the sheet P to which the air is blown by the air blowing means 3 floats freely. The sheet that has been in close contact is separated by this floating state, but the sheet P is greatly disturbed toward the downstream side in the sheet conveying direction. Therefore, at the timing of blowing air by the air blowing means 3,
For example, the solenoid 6 is driven to operate the advance restricting means 4 so as to press the upper surface of the sheet P. Due to the pressing by the advance regulating means 4, the sheet P is loosened without disturbing the stacking posture, and the sheet P is released.

As another method for restricting the advance of the sheet P, the control means 5 presses the sheet retraction means 2 against the upper surface of the sheet P at the timing when air is blown by the air blowing means 3. Since this pressed state is not for the purpose of transporting the sheet P, the sheet retraction unit 2 does not rotate but has a function of pressing the sheet P and restricting the forward movement due to the disturbance of the loading posture.
That is, the sheet retraction unit 2 provided for the purpose of retrieving and conveying the sheet P is controlled by the control unit 5 so as to press the upper surface of the sheet P in synchronization with the timing of the air blowing for the purpose of preventing a forward disturbance. You.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1 Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings. FIG. 2 shows an embodiment of an image forming apparatus to which the present invention is applied. In the figure,
The image forming apparatus 21 as a sheet feeding apparatus includes an image reading apparatus (IIT) 23 for reading a document image and a receiving unit 29 connected to an external device 25 such as a personal computer (PC) via a communication line 27. , The image writing device 31 based on the image information from the receiving unit 29.
Is provided with an image recording control section 33 for controlling the image recording. The image recording control unit 33 controls the image writing device 31,
The control of the sheet supply unit 60 described later and the control of another sheet conveyance system are also executed. The image forming apparatus 21 has an image carrier 35 on which an electrostatic latent image is written by the image writing device 31, and is 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 using toner, and transfers the toner image on the image carrier 35 to the sheet conveyed by the transfer roller 43. ing. Furthermore,
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 cleaner 41 for collecting the remaining toner not used for the transfer are provided.

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 sheets 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 raised 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 section 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. In the present embodiment, the pull-in roll 61, the transport roll 62, and the separation roll 63 are formed of a specific material described later, and are formed of rolls having the same shape and the same size as each other. By doing the sheet P
Is configured to perform the transport operation of

The transport roll 62 is driven by receiving power from a feed motor (not shown) via a drive gear and a feed clutch (not shown). On the other hand, the draw-in roll 61 is configured to rotate around an axis 62 a of the transport roll 62 via an arm 81, and is rotated by gears 82 in conjunction with driving of the transport roll 62. Further, the pull-in roll 61 falls on the upper surface of the sheet P via the link 84 by the operation of the solenoid 83 which operates in response to a drive signal from the image recording control unit 33, and rotates with a predetermined pressing force. By driving, the sheet P can be fed out. Also, the arm 81
Is detected by the photo sensor 85, and when a predetermined number of sheets P are conveyed and the upper surface of the sheets P is lowered, the bottom plate in the sheet supply tray 59 is raised, and The height is configured to be within a certain range.

The draw-in roll 61 in the present embodiment is
The sheet P is transported to the downstream transport roll 62 and the separation roll 63.
The sheet P is conveyed to the nip portion of
It is comprised so that it may be separated from. If the sheet P is pressed against the sheet P even after the pull-in operation is completed, the sheet P rotates with the pressure even when the rotation is turned off, and a conveying force is applied to the second and subsequent sheets P, resulting in excessive supply. Causes double feed. Therefore, when the sheet P is not supplied and the sheet is not fed, the pull-in roll 61 is once pulled up and separated from the upper surface of the sheet.

Further, the separating roll 63 is brought into contact with the transporting roll 62 with a small pressure by a spring 89 via a support 88 having a pivot 87 as a center of rotation. Further, the separating roll 63 is connected to a first gear 91 and a fixed second gear 92 via a torque limiter 90. Here, when the separating roll 63 rotates with the transport roll 62, the sliding torque of the torque limiter 90 is transmitted to the first gear 91 via the retard shaft 63a, and the first gear 91 tries to rotate clockwise. Since the second gear 92 is fixed, the first gear 91 operates to ride on the second gear 92, and as a result, the retard pressure, which is the pressure on the transport roll 62, is increased.

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.

If it is attempted to convey the coated paper or the like as the sheet P in such a setting state, a plurality of coated papers are conveyed together because the adhesion between the coated papers is extremely high. As a result, they are transported downstream as double feeds. Here, the coated paper is a composite sheet in which Western paper is used as a base paper, and a coating color, which is a kind of paint, is applied to both sides or one side thereof for the purpose of improving printability. This coated paper has a very high surface smoothness, the gap between the coated papers when they are in contact with each other is in a very narrow state, the air pressure does not pass through the gap, and the negative pressure generated is maintained, As a result, the adhesion between the sheets is increased, and the coated paper cannot be separated by the contact pressure with respect to ordinary plain paper or copy paper. At this time, the experiment by the inventor found that simply increasing the contact pressure to separate coated paper would require a contact pressure approximately 30 times that of ordinary plain paper or copy paper. Clarified. On the other hand, in order to maintain the coefficient of friction on coated paper, each roll is formed using a material with low abrasion resistance. It became clear that it would be shorter.

Therefore, in this embodiment, an air blowing device 71 is provided as one of the means for eliminating adhesion to a sheet P having high adhesion such as coated paper, and high-pressure air is blown onto the sheet P, so that the sheet P is blown. The contact of the sheet P is eliminated, and the supply of the sheet P is enabled without increasing the contact pressure of each roll. Here, the air outlet 73 of the air blowing device 71 shown in FIG. 4 has its lower opening lower than the uppermost sheet P on which it is stacked, and the upper opening upper than the uppermost sheet P. It is configured.
For example, by intermittently blowing air from the air outlet 73, a lift as shown 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 substantially one by one, and even when a plurality of sheets are fed out collectively, the sheet P is separated and conveyed by the conveying roll 62 and the separating roll 63 one by one. You.

In the present embodiment, the close contact of the sheet P by blowing air is performed before the draw-in roll 61 draws the sheet P by rotational driving, that is, during a so-called standby state. The standby state is when the operator (user) using the image forming apparatus 21 sets the sheet supply tray 59 with respect to the apparatus main body, or temporarily turns off.
When the power supply is turned on, when the energy saving mode is cancelled, there is a certain time before the actual image formation is performed, and the like. When set, air blowing, which is a means for eliminating adhesion, is effective. In the present embodiment, at least the sheet supply tray 59
When the air blowing device 7 is set for about 30 seconds,
1 is controlled to blow high-pressure air. The spraying time and frequency can be changed depending on the expected difference in the degree of adhesion of the sheet P. For example, the type of sheet having different surface smoothness or thickness (for example, designated by an operator), the influence on the degree of adhesion, etc. Can be controlled to change based on environmental conditions (detection by a sensor) such as high humidity.

In this way, by blowing air from the air blowing device 71, it is possible to eliminate the close contact of the sheet P, but on the other hand, the stacking posture of the levitated sheet P is disturbed, which causes heavy load. Problems have been pointed out in that transport failures such as transport occur. That is, as described above, the sheet P
In the state where the retraction operation is not performed, the retraction roll 61 is separated from the sheet P and the sheet P is in a free floating state. Here, as shown in FIG. An end guide 65 is provided at the rear end,
Side fixed guide 6 on the side surface in the direction perpendicular to the paper feeding direction
7 and a movable side guide 69 are provided, so that there is no significant disturbance to the rear end in the sheet feeding direction and both side surfaces orthogonal to the sheet feeding direction. However, there is no restriction on the front in the sheet feeding direction, so that the levitated sheet is greatly disturbed in the sheet feeding direction, and the second and subsequent sheets P to be supplied later precede the first sheet. There is a case where the paper is supplied, and as a result, a double feed trouble occurs.

Therefore, in this embodiment, based on the instruction of the image recording control unit 33, the state shown in FIG.
The pull-in roll 61 is dropped on the upper surface of the sheet P by operating the solenoid 83 shown in FIG. That is, the pull-in roll 61, which is originally a roll for pulling in the stacked sheets P, is operated so as to press the upper surface of the sheet P at a timing not necessarily coincident with the supply of the sheet P, thereby feeding the sheet P. Air was blown while the front end in the direction was pressed. At this time, no driving force is applied to the draw-in roll 61. With such a configuration, in a state where the advance of the sheet P is regulated, the close contact of the sheet P is eliminated by the levitation operation by air blowing, and at the same time, the disturbance of the front end of the sheet P in the sheet feeding direction is suppressed. For this reason, conveyance troubles such as double feeding and paper feeding failure can be prevented beforehand, and extremely stable sheet supply can be realized. It is sufficient that the drawing roll 61 is pressed when air is blown from the air blowing device 71, and the image recording control unit 33 can control the drawing roll 61 so that the pressing state of the drawing roll 61 is continued before and after that. It is possible.

As described above, according to the present embodiment, when the air is blown from the air blowing device 71, which is the close-contact elimination means, the sheet P is pressed down from the upper surface of the sheet P by the draw-in roll 61, whereby the air blowing is performed. At the same time, the roll used for sheet supply can be used as it is,
It is not necessary to newly provide another mechanism only by the control operation of the image recording control unit 33, and an excellent function can be obtained while suppressing an increase in cost.

Second Embodiment In the first embodiment, the advance of the sheet is regulated by pressing the draw-in roll 61 when blowing air from the air blowing device 71. In the present embodiment, the sheet is separately provided. This is to prevent the stacking posture of the sheets P from being disturbed by using the stopper. The same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the detailed description thereof will be omitted.

FIG. 6 is a schematic explanatory view showing the sheet supply tray 59 in the second embodiment from the side. In the present embodiment, a stopper 101 for pressing the front end of the sheet P in the sheet feeding direction is newly provided, and the front end of the sheet P is pressed at the time of air blowing by the air blowing device 71.
This controls the advance of the sheet P. That is, a stopper 101 that rotates via a fulcrum 103 is provided on the downstream side of the draw-in roll 61, and one end of the stopper 101 is provided at the front end of the sheet P in the conveying direction in the sheet stacked on the sheet supply tray 59. It is located so that it can contact the upper surface of P. The sheet pressing operation of the stopper 101 is performed by using the linear motion of the solenoid 102 and the fulcrum 103.
, And the movement of the solenoid 102 is controlled based on a signal from the image recording control unit 33 in synchronization with the air blowing timing by the air blowing device 71. This stopper 10
1 is controlled so as to be separated from the upper surface of the sheet P when the draw-in roll 61 drops onto the upper surface of the sheet P and supplies the sheet P, so that there is no trouble in sheet supply. .

According to the present embodiment, a mechanism that is independent of the sheet supply operation of each roll in the sheet supply unit 60 is used to prevent the sheet P from being disturbed during air blowing. The control operation in the sheet supply unit 60 including the independent mechanism unit can also be simplified. Further, the position where the sheet is pressed is the stopper 101
The stopper 10 can be set arbitrarily by changing the mounting position of the stopper 10 at an optimum position in consideration of the air blowing structure by the air blowing device 71 and the air flow.
1 can press the sheet P. As a result, it is possible to prevent the sheet P from being disturbed while maximizing the function of separating the sheet P by blowing air.

Third Embodiment In the second embodiment, the separately provided forward regulating means includes:
Although the stopper 101 operated by the solenoid 102 is employed, in the present embodiment, a stopper having no special driving source is disposed at the front end of the sheet P.
The same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the detailed description thereof will be omitted.

FIG. 7 is a schematic explanatory view showing the sheet supply tray 59 in Embodiment 3 from the side. In the present embodiment, as shown in FIG.
A coil spring stopper 110 is provided at the front end in the sheet feeding direction of the sheets P stacked on the sheet P. The coil spring stopper 110 is a linear member having a spring structure configured to rotate via a fulcrum 111.
Is fixed to the apparatus body. Coil spring stopper 1
When the sheet P is not conveyed, it is located at the solid line position in FIG. 7 and is in contact with the front end of the sheet P. When the sheet P rotates in the direction of the arrow in FIG. It is designed to hold the force. That is, when the sheet P is disturbed by air blowing by the air blowing device 71 and is weak enough to move forward, the front end of the sheet P is aligned by the spring force of the coil spring stopper 110, and the drawing roll 6
With respect to the conveying force given to the sheet P by 1, the sheet P is pushed and rotated in the arrow direction to open the sheet conveying path so that there is no trouble in sheet supply. In the present embodiment, the coil spring stopper 110 is provided at the center of the front end in the direction perpendicular to the sheet conveyance direction. However, a plurality of coil spring stoppers are provided at both ends at the front end in the direction perpendicular to the sheet conveyance direction. Stopper 110
It is also possible to arrange.

According to the present embodiment, there is no need to provide a drive source such as a solenoid for preventing the sheet from being disturbed when air is blown, and high performance can be obtained with an inexpensive configuration. Further, this embodiment is excellent in that the alignment and conveyance of the sheet can be performed by utilizing the force of the sheet P, and a complicated control operation is not required. In the present embodiment, a stopper made of a coil spring is used. However, the stopper is not limited to this as long as a similar function can be obtained.
The same function can be obtained by installing a mylar sheet having a shape.

In the first to third embodiments, the operation at the time of releasing contact by so-called air blowing at the time of standby is described. However, air blowing by the air blowing device 71 is performed at the time of sheet supply other than at the time of standby, for example. May also be performed.

[0037]

As described above, according to the present invention,
Disturbance in the stacking posture of the sheets caused by air blowing before the sheet feeding operation can be reduced, and advance of the sheets can be prevented, so that occurrence of double feed or the like during sheet supply can be prevented.

[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 a schematic explanatory view showing a sheet supply tray according to the second embodiment from the side.

FIG. 7 is a schematic explanatory view showing a sheet supply tray according to a third embodiment from the side.

FIG. 8 is an explanatory diagram for explaining a problem of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sheet accommodation means, 2 ... Sheet retraction means, 3 ... Air blowing means, 4 ... Progress control means, 5 ... Control means, 6 ...
Solenoid, 7: sheet separating means, 21: image forming device, 31: image writing device, 33: image recording control unit, 35
.., Image carrier, 37 charger, 39 developing device, 43 transfer roller, 45 fixing device, 59 sheet supply tray,
Reference numeral 60: sheet supply unit, 61: pull-in roll, 62: transport roll, 63: separating roll, 65: end guide, 67:
Side fixed guide, 69 movable side guide, 71 air blowing device, 73 air outlet, 101 stopper, 102 solenoid, 103 fulcrum, 110 coil spring stopper, 111 fulcrum, 201 roll-in roll, 202: Air blowing means, P: Sheet.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3F343 FA02 FB02 FB04 FC01 GA01 GB01 GC01 GD01 HA12 HB04 HC30 HD16 JA01 JD03 JD09 JD28 JD33 KA06 KA13 KA14 LA04 LA15 LC17 LC19 LD11

Claims (4)

[Claims] A sheet storage unit configured to store a sheet, a sheet retraction unit configured to operate toward the sheet when the sheet is supplied from the sheet storage unit and to contact the upper surface of the sheet to draw the sheet; An air blowing unit that blows air against an end face of a sheet stored in the sheet storing unit during standby when the sheet is not supplied from the sheet storing unit by the sheet drawing unit; and the air blowing unit during standby. A sheet feeding device comprising: a sheet feeder for stopping sheet advance while blowing air. 2. The sheet feeding device according to claim 1, wherein the air blowing unit blows air for a predetermined time after setting the sheet storage unit in the apparatus main body. 3. The sheet feeding apparatus according to claim 1, wherein the advance regulating unit regulates the advance of the sheet by pressing a sheet stored in the sheet storing unit from above. 4. A sheet accommodating means for accommodating a sheet, and a sheet retracting means which contacts the upper surface of the sheet when the sheet is supplied from the sheet accommodating means and retracts the sheet, and separates from the upper surface of the sheet when no sheet is supplied. An air blowing unit that blows air against an end face of a sheet stored in the sheet storage unit during standby when the sheet is not supplied from the sheet storage unit by the sheet pull-in unit; A sheet feeding device, comprising: a control unit that controls the sheet retraction unit to contact the upper surface of the sheet while the air is being blown by the blowing unit so as to regulate the advance of the sheet.