JPH07277541A - Paper feeder and image formation device - Google Patents

Abstract

PURPOSE:To provide a paper feeder which does not generate defective paper feeding both in the case of a small-sized sheet and in the case of a large-sized sheet delivered lengthwise and in addition whose constitution is simple. CONSTITUTION:Air is jetted toward the tip of a sheet on a tray 100 by means of an air blowing nozzle 106, and at the same time air is also jetted toward the sheet side ends by means of nozzles 124, 125 fixed at side regulating slabs 120, 121. In this constitution, it becomes possible to blow air in to the rear end of a large-sized sheet placed lengthwise on the tray 100. As a result, large- sized sheets can be surely separated from each other one by one and can be fed (delivered lengthwise). Also, by controlling by means of a valve air jetting to the sheet side ends that is by means of the nozzles 124, 125 and conducting this air jetting only at the time of large-sized sheet feed, the flapping of small- sized sheets and defective paper feeding caused by it can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, which separates and feeds stacked sheets of original documents or recording sheets.

[0002]

2. Description of the Related Art A stack of single-cut originals are sequentially fed one by one from the top or bottom, and the fed originals are returned to the bottom or top of the stacking position after being read. In an image forming apparatus such as a copying machine equipped with an automatic automatic document feeder (RDH) or various printing devices and printing devices, sheets of stacked single-cut originals and recording sheets are separated and fed one by one. A sheet feeding device is provided.

In such a sheet feeding device, one sheet is fed.
As the means for separating the sheets one by one, there are a separation method by air injection, a separation method by a separation claw, a separation method by a roller which rotates in the opposite direction to the sheet feeding direction, and the like.

Among these, as a conventional example of a sheet feeding device provided with a separation system by air injection, there is the "sheet feeding device" of Japanese Patent Laid-Open No. 58-8932. 3,198,524 (Japanese Patent Publication No. 55-19857).

FIG. 6 is a side sectional view showing the structure of the sheet feeding device in the above conventional example, FIG. 7 is a plan view thereof, and FIG. 8 is a supporting tray 3 on which recording sheets 2 are stacked in this sheet feeding device.
FIG.

As shown in the figure, in this paper feeding device, a notch 4 is formed at the center of the end of the supporting tray 3 on the downstream side in the paper feeding direction G, and a pair of rotating rollers 5 and 6 below the supporting tray 3 is provided. The paper feed belt 7 having a large number of stretched through holes is exposed at the notch 4. An air intake duct 8 facing the notch 4 via a paper feed belt 7 between the pair of rotating rollers 5 and 6.
Is arranged, the lowermost one of the recording papers 2 on the support tray 3 is vacuum-sucked to the paper feeding belt 7, and the paper is fed by the traveling drive of the paper feeding belt 7.

On the other hand, a plurality of recording papers 2 on the support tray 3 may be adsorbed to the paper feed belt 7 at the same time to be fed, so that the recording papers 2 on the support tray 3 are air-flowed upward in the paper feed direction G from the support tray 3. An injection duct 9 is provided, and the duct 9 has a sheet feeding direction G.
The nozzles 10b to 10e that are parallel to the nozzles 10a and 10f and the plurality of nozzles 10a and 10f that face the center of the support tray 3 concentrate and blow air on the leading edge of the recording paper 2 so that only the bottommost sheet is separated. ing. The distribution of the air flow on the recording paper 2 by the air injection duct 9 is as shown by the hatched lines in the explanatory view of FIG.

Further, in order to make the recording paper 2 easier to separate, the support tray 3 has a base portion 14 which is widened from the downstream side to the upstream side in the sheet feeding direction G, and the base portion 14
Side wings 15 and 16 are formed obliquely upward from both widthwise side portions of the.

[0009]

In the paper feeding apparatus having the above-described structure, large size recording paper such as A3 or B4 is placed on the support tray 3 so that its long side is perpendicular to the paper feeding direction. In the case of so-called large-size transverse feeding, the recording sheets are well separated. However, if the large size lateral feed is performed, the depth of the paper feeding device becomes very large, and the photosensitive drum and the fixing roller for forming an image on the recording paper also need to be large.

Therefore, when the large-sized recording paper is vertically placed on the support tray 3 and vertically fed by the above-mentioned conventional paper feeding device, this time, it is sprayed from the nozzle 10 toward the front end of the recording paper. It is difficult for air to reach the trailing edge of the recording paper, so that no air gap is formed between the lowermost recording paper and the above-mentioned bundle of recording paper. As a result, double feeding occurs due to the frictional force in the contact area at the rear of the recording paper.

In this case, it is conceivable to increase the pressure and flow rate of the air flow from the nozzle 10 of the air injection duct 9 so that the air flow reaches the rear end of the large size recording paper. As the pressure and the flow rate rise, the shape of the blade of the blower for generating the air flow and the number of rotations also increase, which causes a problem that noise increases.

In addition, since the pressure and flow rate of the air flow that allows the air flow to reach the rear end of the large size recording paper are excessive for the small size recording paper, the stacking state is It may be disturbed and, on the contrary, may lead to a paper feed failure.

When the number of recording sheets on the support tray 3 is gradually reduced to a small number, the disorder of the stacked state of recording sheets becomes particularly remarkable. This becomes a more serious problem in thin paper and small size paper having a small basis weight among the recording papers used. As a measure to avoid this, it has already been proposed to adjust the air flow by a valve provided in the air injection duct 9 according to the size and basis weight of the recording paper, or the number of sheets loaded, but in this case, ,
Since the flow rate and the pressure are set so that the air flow reaches the trailing edge of the large-sized recording paper placed vertically, the flow rate and the pressure of the air flow are considerably increased.

For this reason, even if the air flow is adjusted by the valve, the flow rate and pressure of the delicate air flow can be adjusted so as to cope with even the most problematic case such as stacking a small number of thin thin papers. It is impossible to make adjustments. Even if such a delicate adjustment is possible, the configuration for achieving it must be complicated, and on the contrary, it may lead to a decrease in the reliability of the entire sheet feeding device. Absent.

The present invention has been proposed in order to solve the above-mentioned problems, and it is possible to cause a paper feed failure regardless of whether it is a small size sheet or a large size sheet to be fed vertically. It is an object of the present invention to provide a paper feeding device that does not have a simple structure.

[0016]

A sheet feeding device (101) according to the present invention comprises a tray (10) on which a plurality of sheets are stacked.
0), a sheet feeding unit (102 to 105) for vacuum-sucking and feeding the sheet on the tray, and a first air jetting unit (1) for jetting air toward the leading end of the sheet on the tray.
06), and second air injection means for injecting air toward the side edge of the sheet on the tray (124, 125, 12).
8), and a control means (129) for controlling the air injection by the second air injection means.

[0017]

In the sheet feeding device (101) having the above structure, the first air ejecting means (106) ejects air toward the leading edge of the sheet on the tray (100) and the second air ejecting means (124, Since air is jetted toward the sheet side edge by means of 125, 128), it is possible to blow the air even to the rear edge of the large size sheet vertically arranged on the tray (100). As a result, it is possible to reliably separate and feed the large size sheets one by one (vertical feed).

The second air injection means (124, 12)
5, 128) is controlled by the control means (129) to inject the air to the side edge of the sheet, and is performed only at the time of feeding the large size sheet. It is possible to prevent defects.

The reference numerals in the above parentheses are for comparison with the drawings and do not limit the structure of the present invention.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a sheet feeding device in the embodiment,
FIG. 2 is a side sectional view thereof. In addition, FIG. 3 shows EE of FIG.
FIG. 4 is a diagram showing a state when a small size sheet is stacked in a line sectional view, and FIG. 4 is a diagram showing a state when a large size sheet is stacked in a sectional view taken along the line EE of FIG.

The sheet feeding device 101 is provided with a sheet tray 100 on which sheets S are stacked, and a sheet adsorbing unit disposed below the sheet tray 100 on the upstream side in the sheet feeding direction to adsorb the lowermost sheet S1. Conveying means for conveying the lowermost sheet S1 adsorbed by the sheet adsorbing means, and an air blowing nozzle (first air ejecting means) for ejecting air toward the tip of the sheets S stacked on the sheet tray 100. 106 and a guide plate 108 that regulates the leading edge of the sheet S.

The sheet suction means has a first suction chamber 102 having a suction opening 102a in the upper portion and a second suction chamber 103 having a suction opening 103a in the upper portion.
And a blower 105 connecting both suction chambers 102 and 103. First located upstream
Of the suction chamber 102 is arranged so that the suction opening 102a is inclined downward as it goes to the upstream side, and the second suction chamber 103 located on the downstream side is arranged so that the suction opening 103a is substantially horizontal. Has been done.

The transfer means is provided with the suction openings 10 of the first and second suction chambers 102 and 103, respectively.
Conveyor belt 10 arranged to cover 2a and 103a
4 and constitutes a sheet feeding means together with the sheet suction means. The conveyor belt 104 has a plurality of suction holes 104a.
And a conveyance surface for adsorbing a sheet has an inflection point 10 between the first suction chamber 102 and the second suction chamber 103.
7, a plurality of rollers 104b appropriately arranged so as to be bent at a predetermined angle θ. Also,
The conveyor belt 104 is adapted to rotate by being transmitted with a driving force of a motor (not shown).

The first suction chamber 102 and the portion of the conveyor belt 104 corresponding to the first suction chamber A constitute the first suction portion A, and the second suction chamber 103 and the portion of the conveyor belt 104 corresponding to the first suction chamber A. 2 to form the adsorption portion B.
The suction surface of the first suction portion A is inclined at a predetermined angle θ, and the suction surface of the second suction portion B is arranged substantially horizontally.

The sheet tray 100 has a cutout 10
0a is formed, and the sheet suction means and the conveyance means are arranged in this cutout portion 100a. The sheet tray 100 also has a base portion 100b at the center in the width direction and both side portions 100c formed so that both sides in the width direction form an angle upward from the base portion 100b. The base portion 100b is substantially parallel to the transport surface on the first suction chamber 102 side and is arranged so as to uniformly contact the sheet S.

The air blowing nozzle 106 is arranged so as to inject air from above the downstream side of the sheet tray 100 toward the upper surface of the second suction portion B. Further, this air blowing nozzle 106, as shown in FIG.
A plurality of sheets are provided at positions corresponding to the suction area of the conveyor belt 104 in the width direction of the sheet S, and an air flow from a blower (not shown) is applied to the leading edge of the sheet.

The guide plate 108 is the conveyor belt 104.
The sheet S is vertically provided at a position corresponding to the downstream end of the sheet S, and the leading edge of the sheet S on the sheet tray 100 is brought into contact with the sheet tray 100 to regulate the sheet. The guide plate 108 and the conveyor belt 1
A passage for sending out the separated sheet S is formed between the sheet S and the sheet 04.

In the above structure, the suction force of the blower 105 allows the suction openings 102a, 1a from the first suction chamber 102 and the second suction chamber 103, respectively.
03a and the suction holes 104a of the transport belt 104, the sheet S is attracted to the transport belt 104. that time,
Since the suction surface of the conveyor belt 104 is bent at a predetermined angle θ, only the lowermost sheet S1 is sucked, and the other sheets S are straightened by the strength of their strains (rigidities). Only the lower sheet S1 is separated. At the same time, by blowing air from the air blowing nozzle 106 between the lowermost sheet S1 and the uppermost sheet S, the upper sheet S is floated, and only the lowermost sheet S1 is surely secured. Separate and feed.

The sheet feeding device 101 of the present embodiment is used for copying on both sides of a sheet or multiplex copying on one side of a sheet, as in an image forming apparatus (copier) described later.
It is used as a device for temporarily stocking sheets once copied on one side and re-feeding them.

Therefore, in the sheet feeding device 101, when a sheet of which one side is copied through a process described later is stored in the sheet tray 100, a pair of side regulating plates 120 and 121 provided on the sheet tray 100 are The position is automatically adjusted according to the sheet size to regulate the side edge of the sheet S on the tray 100 and adjust the position of the sheet in the width direction.

The side regulating plates 120 and 121 are provided with notches 122a and 122 provided in the sheet tray 100.
b, 123a, 123b, and is formed so as to project from above onto the sheet tray 100.
A rack and a pinion gear etc. move along 2a, 122b, 123a, 123b. It should be noted that the side regulating plates 120 and 121 may be arranged to abut on the side edge of the sheet after storing the sheet and adjust the position thereof as described above, or may be set to be slightly wider than the sheet size in advance. The sheet position may be adjusted by receiving the sheet discharged to the intermediate tray after being moved to the width and then corrugated.

As shown in FIGS. 3 and 4, the side regulating plates 120 and 121 face nozzles (second air ejecting means) 124, respectively, which face the openings provided in the side regulating plates 120 and 121.
125 is fixed, and each nozzle 124, 125 is
Flexible tubes 127 and 132 and duct 131
An air flow from a separately provided blower (second air ejecting means) 128 is ejected toward the side edge of the sheet S via.

That is, in this paper feeding device 101, in addition to the above air blowing nozzle 106, each of the above nozzles 12
Nos. 4 and 125 are provided, and air is blown between the sheets S also from the side edges thereof, so that even when a large size sheet is vertically fed, the sheets are reliably separated and fed.

The positions and orientations of the nozzles 124 and 125 should be set so as to complement the above-mentioned sheet separating action of the air blowing nozzle 106 on the sheet front end side, as shown by arrows C and D in FIG. In addition, it is preferable to set the air flow to be ejected toward the rear end of the sheet S, that is, toward the sheet rear end regulating plates 126a and 126b movable in the sheet feeding direction. In addition, each of the nozzles 124, 125
The position in the sheet feeding direction is preferably a position corresponding to the boundary between the floating portion and the non-floating portion when the leading edge side of the sheet of the maximum large size is floated by the air blowing nozzle 106. According to this, the position corresponding to approximately 1/2 of the length in the sheet feeding direction (long side length) of the maximum large size is optimal.

Further, regarding the vertical direction of each of the nozzles 124 and 125, both side portions 1 of the sheet tray 100 are
00c parallel to the sheet mounting surface, or slightly upward from the sheet mounting surface (angle α in FIG. 4),
Allow air to enter efficiently between the seats.

Then, the side regulating plates 120 and 121
The injection of the air flow from the nozzles 124 and 125 provided in the
A3, B4, LDR, L controlled by a valve (control means) 129 driven by a solenoid (not shown)
This is performed only when a large size sheet such as GL that is appropriately selected is fed. As a result, the air separation of the large size sheet is effectively performed, and at the same time, the flapping of the small size sheet and the paper feeding failure due to the flapping are prevented. The blower 128 is provided with a regulating valve 130 to allow air to escape from the blower 128 when the valve 129 is closed.

Further, the nozzles 124 on the sheet side end side,
The ejection timing of the air flow from 125 is assumed to be after the ejection of the air flow from the air blowing nozzle 106 on the leading edge side of the sheet has started and the front side of the sheet S has floated. This timing prevents unnecessary flapping of the seat.

As described above, in this paper feeding device 101,
An air blowing nozzle 106 that injects air toward the front end of the sheet, and a nozzle 1 that injects air toward the end on the sheet side.
With 24 and 125, the air can be blown even to the rear end of the large size sheet vertically placed on the sheet tray 100, so that the large size sheets are reliably separated one by one and fed (vertical direction). It is possible to prevent the double feed.

Further, the side regulating plates 120, 12 are provided with nozzles 124, 125 for injecting air toward the sheet side ends.
Since it is fixed to No. 1, air can be efficiently blown into any size sheet on the sheet tray 100 in a state of being close to the side edge thereof.

The flow rate of the air flow from each of the nozzles 124 and 125 may be adjusted by valve means according to the number of stacked sheets and the basis weight.

Furthermore, the nozzles 124 and 125 are
A plurality of side regulating plates 120 and 121 may be provided, and the cross-sectional shape of the nozzles 124 and 125 can be appropriately selected by combining with the blower 128.

As for the blower 128, instead of this, the exhaust air from the blower 105 for suction is supplied to the duct 1
It may be configured to lead to 31. In this case, the number of blowers can be reduced, resulting in a cost advantage, and the reduction of blowers as electric parts leads to improvement in reliability of the sheet feeding device. Moreover, since the air can be efficiently acted upon separating the sheets, the size and the rotation speed of the blower do not become unnecessarily large, and there are great advantages in terms of noise and cost.

Next, an image forming apparatus (copying machine) equipped with the above-described paper feeding device 101 will be described with reference to the sectional view of FIG.

As shown in the figure, the image forming apparatus main body 200 includes a document placing table 206, a light source 207, a lens system 208,
A sheet feeding unit 209, an image forming unit 202, and the like are provided.
The paper feed unit 209 includes a paper feed tray 210, a cassette 211, and a paper deck 213. Image forming unit 20
2, a cylindrical photosensitive member 214, a developing device 215 containing a toner, a transfer charging device 216, a separation charging device 217, a cleaner 218, a primary charging device 219, etc. are arranged. At the downstream side of the image forming unit 202, the transport device 22
0, a fixing device 204, a discharge roller 205, and the like.

In this image forming apparatus, when a sheet feeding signal is output from a controller (not shown) provided in the apparatus main body 200, the sheet S is fed from the sheet feeding tray 210, the cassette 211 or the paper deck 213. It On the other hand, the light emitted from the light source 207 and reflected on the original placed on the original placing table 206 is condensed on the photoconductor 214 via the lens system 208. The photoconductor 214 is previously charged by the primary charger 219, an electrostatic latent image is formed by the reflected light from the document, and then a toner image is formed by the developing device 215.

The sheet S fed from the paper feeding unit 209 is
The skew feeding is corrected by the registration roller 201, and the timing is adjusted to send the image to the image forming unit 202. In the image forming unit 202, the transfer charger 216 transfers the toner image on the photoconductor 214 to the sheet S that has been sent,
The transferred sheet S is charged with a polarity opposite to that of the transfer charger 216 by the separation charger 217, and the photosensitive member 214 is charged.
Separated from.

Then, the separated sheet S is conveyed to the fixing device 204 by the conveying device 220, and the unfixed transferred image is permanently fixed by the fixing device 204. The sheet S on which the image is fixed is discharged to the outside of the apparatus main body 200 by the discharge roller 205.

On the other hand, in the case of double-sided copying or multiplex copying, the sheet copied on one side is discharged to the sheet tray 100 of the sheet feeding device 101 in the direction of arrow F. Then, as described above, the sheets stacked on the sheet tray 100 are reliably separated one by one from the lowermost part and re-fed, and sent from the registration roller 201 to the image forming unit 202 to be copied again. . As a result, first, the paper feeding unit 2
The sheet S fed from 09 is subjected to double-sided copying or multiple copying and is discharged to the outside of the apparatus main body 200.

The present invention is not limited to the above embodiment, but may be applied to, for example, an automatic document feeder (ADF) for automatically feeding a document.

As this automatic document feeder, for example,
A document tray 300 on which a document is placed, as shown in FIG.
A sheet feeding device 301 to which the present invention is applied, a conveying belt 302 that sandwiches and conveys a document sent from the document tray 300 by the sheet feeding device 301 with a document placing table 206, a light source 207, and a lens system. There is one that is roughly configured by a discharge tray 303 on which a document whose image is read by a document reading unit configured by 208 and the like is stacked.

It is also possible to separate the stacked sheets one by one from the top and feed them.

[0053]

As described above, according to the paper feeding apparatus of the present invention, both small size sheets and large size sheets to be fed vertically can be reliably separated and fed one by one. Paper can be used, and double feeding and paper feeding failure do not occur. Moreover, since the structure is simple and the control of air injection is simple, it can be easily realized.

Further, since the air can be efficiently blown to the stacked sheets from the sheet front end and the sheet side end, the size and the rotational speed of the blower for generating the air flow do not become unnecessarily large. Therefore, great advantages can be obtained in terms of cost and noise.

Further, since a large size sheet can be reliably fed in the vertical direction, the size of the entire sheet feeding device can be made compact and the image forming apparatus in which this sheet feeding device is arranged is also small. Can be converted.

By disposing the sheet feeding device having no sheet feeding defect in the image forming apparatus, the reliability of the image forming apparatus can be improved.

[Brief description of drawings]

FIG. 1 is a plan view of a sheet feeding device according to an embodiment of the present invention.

FIG. 2 is a side sectional view thereof.

FIG. 3 is a cross-sectional view taken along the line EE in FIG. 1, showing a state in which small size sheets are stacked.

FIG. 4 is a cross-sectional view taken along the line EE in FIG. 1, showing a state when a large size sheet is stacked.

FIG. 5 is a cross-sectional view of an image forming apparatus (copier) including a paper feeding device according to the present invention.

FIG. 6 is a side sectional view of a sheet feeding device in a conventional example.

FIG. 7 is a plan view thereof.

FIG. 8 is a perspective view of a support tray of a sheet feeding device in a conventional example.

FIG. 9 is an explanatory diagram of an air flow distribution of a sheet feeding device in a conventional example.

[Explanation of symbols]

100 Sheet Tray 101 Paper Feeding Device 102, 103 Suction Chamber (Paper Feeding Unit) 104 Conveyor Belt (Paper Feeding Unit) 105 Blower (Paper Feeding Unit) 106 Air Blowing Nozzle (First Air Injecting Means) 120, 121 Side Regulation Plates 124, 125 nozzles (second air injection means) 128 blower (second air injection means) 129 valves (control means) 200 image forming apparatus main body 202 image forming unit

Claims (6)

[Claims] 1. A sheet feeding device for separating and feeding the stacked sheets one by one, and a tray on which a plurality of sheets are stacked, and a sheet feeding means for vacuum suctioning and feeding the sheets on the tray. A first air ejecting unit that ejects air toward the front end of the sheet on the tray; a second air ejecting unit that ejects air toward the side end of the sheet on the tray; And a control unit for controlling the air injection by the air injection unit. 2. A side regulating plate that regulates a side end of a sheet stacked on the tray, and the second air ejecting means is fixed to the side regulating plate. The paper feeder described in. 3. The sheet feeding device according to claim 2, wherein the side regulating plate is automatically adjusted in position according to the size of sheets stacked on the tray. 4. The feeding device according to claim 1, wherein the second air ejecting unit injects air from a side end of the sheet on the tray toward a rear end thereof. Paper equipment. 5. A sheet feeding device having the structure according to claim 1, and an image forming unit for forming an image on a sheet fed by the sheet feeding device. A characteristic image forming apparatus. 6. A sheet feeding device having the configuration according to any one of claims 1 to 4, and an image reading unit for reading an image of a sheet fed by the sheet feeding device. Automatic document feeder.