JP2000255805A - Paper feeding device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To feed sheets of paper at small intervals by maintaining the paper intervals at constant values and hence correcting the duplicated feed when continuously feeding sheets of paper by a pneumatic paper feeding device. SOLUTION: This paper feeding device has an absorbing sensor 18 for detecting a sheet material being absorbed on a transferring belt 106, and a transfer controlling section 32 for controlling movably-driving of the transferring belt 106. The transfer controlling section 32 allows the transferring belt 106 for transferring the sheet materials to start its movably-driving, based on a sheet material absorption detecting signal from the absorbing sensor 18.

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 an electrophotographic copying machine, and more particularly, to an image forming apparatus using a suction force of air to convert a sheet bundle stacked on a sheet tray.
The present invention relates to a sheet feeding device that separates and conveys sheets one by one and an image forming apparatus including the same.

[0002]

2. Description of the Related Art Conventionally, a sheet feeding device in an image forming apparatus such as an electrophotographic copying machine is generally a roller sheet feeding device which feeds sheets stacked on a sheet tray to a downstream side by rotation of a feeding roller. It is a target. In this conventional roller sheet feeding device, the roller surface is made of an elastic material such as rubber, and the sheet feeding performance largely depends on the friction coefficient of the roller surface. Therefore, if the friction coefficient of the roller surface changes due to the change of the material of the roller with time, the adhesion of paper dust, or the like, the paper feeding performance may become unstable. Further, there are various types of sheets having different surface properties, but there is a drawback that they cannot sufficiently cope with all of them.

[0003] As a solution to such a disadvantage of the roller sheet feeding device, a sheet is attracted by utilizing the suction force of air.
2. Description of the Related Art There has been proposed an air feeding device for conveying. An outline of such an air feeding device will be described with reference to FIGS. FIG. 9 is a cross-sectional view of a conventional paper feeding device.
FIG. 10 is a top view of a conventional paper feeding apparatus.

[0004] The air supplied from the fan 110 is blown out from the nozzle 108, so that the sheet tray 101 is discharged.
Float the upper sheet several sheets. Then, the fan 107
And the suction valve 122 is opened. Then, the uppermost sheet S1 is attracted to the transport belt 106 by the suction force of the fan 107. At this time, by blowing air from the separation nozzle 109 toward the leading end of the sheet, the second and subsequent floating sheets S from the top are pushed back (separation effect).

In this state, the sheet S1 is transported to the transport roller pair 112 by operating the transport belt 106. When the leading end of the sheet S1 reaches the transport roller pair 112, the transport belt 106 stops. Also, the suction valve 1
22 is also closed.

When the sheet S1 is conveyed by a predetermined distance by the conveying roller pair 112, the conveying belt 106 is operated again, and the suction valve 122 is operated.
Is opened, the sheet S2 is sucked, and the sheet S2 is conveyed. That is, every time one sheet is transported, the transport belt 106 and the suction valve 122 are operated / stopped (open / closed).

[0007]

However, in the air feeding apparatus described in the above-mentioned conventional example, the sheet S1 shown in FIG.
The time from when the suction valve 122 is opened to when the sheet S1 is attracted to the transport belt 106 (hereinafter, the attracting time) differs depending on the type and shape of the sheet. For example, 200 g / m
Cardboard such as two sheets, or the tip is downward (sheet tray 10
In the case of a sheet curled in the direction (1), the suction time becomes longer. Conversely, in the case of thin paper such as 52 g / m2 paper or a sheet whose tip is curled upward, the suction time is short.

As described above, since the suction time varies depending on the type and shape of the sheet S1, the time from when the suction valve 122 is opened to when the conveyor belt 106 is operated (hereinafter, referred to as the time).
Paper interval) had to be set longer.

In the air feeding apparatus for low-speed machines, there is no problem because the space between sheets can be sufficiently ensured. However, in the air feeding apparatus for high-speed machines, the time between sheets becomes short. as a result,
When the transport belt 106 is operated, the sheet is not adsorbed to the transport belt 106 or the sheet is insufficiently adsorbed.

Further, in order to increase the productivity of the image forming apparatus, it is necessary to reduce the sheet interval, and it is difficult to implement the air sheet feeding apparatus described in the conventional example.

In addition, in the case of high-speed machines and small inter-sheet feed, since the time for which the separation effect by the separation nozzle 109 described in the above conventional example is exerted when the sheet S1 is sucked is short,
Double feed occurs.

In view of the circumstances described above, the present invention provides a method of feeding a small sheet by continuously maintaining a constant sheet interval and correcting a double feed when a sheet is continuously fed and conveyed by an air sheet feeding apparatus. An object of the present invention is to provide a paper feeder that realizes paper and an image forming apparatus including the same.

[0013]

According to the first aspect of the present invention, which achieves the above object, there is provided a sheet material loading means capable of loading a plurality of sheet materials, and a sheet loaded on the sheet material loading means. A suction means capable of sequentially sucking the material, and a suction conveyance means having a movable movement-movable suction conveyance body to which the sheet material sucked by the suction means can be suctioned;
A sheet material transporting unit that receives the sheet material sucked and conveyed by the suction conveyance unit and conveys the sheet material in a predetermined sheet feeding direction. Providing suction detection means for detecting that the suction has been performed, and providing a conveyance control unit for controlling the movement drive of the suction conveyance body, wherein the conveyance control unit is configured to perform the operation based on a suction detection signal for the sheet material by the suction detection means. And a control unit for controlling the start of movement of the suction conveyance body for conveying the sheet material.

[0014] The invention according to claim 2 of the present invention provides:
2. The sheet feeding device according to claim 1, further comprising a conveyance speed measurement unit configured to measure a conveyance speed of the sheet material between the suction conveyance body and the sheet material conveyance unit, wherein a suction detection signal for the sheet material by the suction detection unit is provided. A suction time calculation unit for calculating a suction time from when the suction of the sheet material is started by the suction means to when the sheet material is sucked by the suction conveyance body, wherein the suction conveyance body and the suction conveyance body are provided. A time calculating unit for calculating a time at which the sheet material conveyed between the sheet material conveying means has passed a predetermined position; a conveying speed measured by the conveying speed measuring means; and a time calculated by the suction time calculating unit. A suction start timing calculation unit that calculates a suction start timing of the suction unit for the sheet material to be conveyed next based on the suction time and the time calculated by the time calculation unit. Provided, based on the suction start timing computed by the suction start timing calculation unit, provided with a suction control section that controls the suction by the suction means.

[0015] The invention according to claim 3 of the present invention provides:
2. The sheet feeding device according to claim 1, wherein the sheet material conveying unit includes first and second pairs of conveying rollers capable of conveying and driving the sheet material arranged in a predetermined conveying direction. And the transport drive speed of the second transport roller pair is individually adjustable.

The invention according to claim 4 of the present invention is characterized in that:
In the paper feeder according to the third aspect, an arrangement interval between the first and second transport roller pairs is changeable.

[0017] The invention according to claim 5 of the present invention provides:
2. The paper feeding device according to claim 1, wherein the suction unit performs suction by an air suction force.

The invention according to claim 6 of the present invention provides
6. An image forming means, comprising: the sheet feeding device according to claim 1; and an image forming unit that forms an image on a sheet material conveyed and fed by the sheet feeding device. An image forming apparatus is characterized in that:

[Operation] With the above configuration, the present invention operates as follows.

1 (Claim 2). At the time of continuous paper feeding, the suction start timing for suctioning the sheet material to the suction conveyance body by the suction means is controlled in accordance with the suction time of the preceding sheet and the conveyance time (conveyance speed and the position and time of the sheet material). As a result, the trailing edge of the preceding sheet material and the leading edge of the next sheet material can be matched, and the sheet can be fed at a constant sheet interval.

2 (Claim 3). When the sheet material is conveyed by the suction conveyance body and the sheet material conveyance means, it is detected by the sheet detection means and the measurement means whether or not the sheet interval is at a predetermined value. The above 1. Does not work well, the sheet interval of the sheet material is not maintained at a predetermined value, and when the sheet material is wide or narrow, the first and second members constituting the sheet material conveying means are not provided.
The control means causes a difference in the conveying speed between the pair of conveying rollers to correct the sheet interval between the sheets.

In the case where the double feeding occurs without the separation effect being exerted at the time of feeding the sheet material. The double feed in this case is not a complete double feed in which the leading ends of the sheet materials coincide, but a double feed in which the leading ends of the preceding sheet and the second sheet material are shifted by a predetermined amount. The length of the sheet material to be conveyed is detected by the sheet detecting means and the measuring means. If this is longer than the transport length of the sheet material, the control means determines that the sheet material overlaps and that double feed has occurred. in this case,
The driving means and the transport drive at a position where the leading edge of the preceding paper is sandwiched between the transport roller pair at the most upstream side of the transport of the two or more transport rollers described above and the second transport roller pair at the downstream side of the transport of the multiple paper feed rollers By stopping part of the means,
Stop the second sheet material. At this time, the trailing end of the preceding sheet of the multi-feed is not sandwiched by the pair of transport rollers on the uppermost stream side of the transport. Further, the rear end of the second sheet of the multi-feed is sandwiched by the pair of transport rollers on the most upstream side of the transport, but the leading end is not sandwiched by the second transport roller pair on the downstream side of the transport. The arrangement of the conveying roller pair and the arrangement of the sheet detecting means configured to be in the state of the sheet material when the multi-feeding is stopped are determined in advance. The leading paper of the double feed is the downstream 2
Since the second conveying roller pair is driven, the sheet is further conveyed to the downstream side of the conveyance, and when the double feeding is corrected, the conveyance of the second sheet of the multi-sheet feeding is started. With the above operation, the double feed generated at the time of feeding the sheet material is corrected.

[0023]

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of the sheet feeding device according to the first embodiment.

FIG. 2 is a top view of the sheet feeding device according to the first embodiment.

FIG. 3 is a front view of the sheet feeding device according to the first embodiment, and is a view as viewed from an arrow A in FIG.

FIGS. 4 to 6 are cross-sectional views of the sheet feeding device according to the first embodiment, and are explanatory diagrams of the sheet feeding operation.

FIGS. 7 (a) and 7 (b) show a sheet feeding device according to the first embodiment, and are simplified cross-sectional views of the transport section 5 shown in FIG.

Parts having the same role as in the conventional example are denoted by the same reference numerals, and description thereof is omitted. In the first embodiment, the sheets are sequentially separated from the top sheet by an air separation method.
This is a paper feeding device of a feeding type.

As shown in FIGS. 1, 2, and 3, the sheet feeding device 1 includes a sheet storage unit 2 for stacking sheets, a separation unit 3 for separating sheets, a suction and conveyance unit 4 for sucking and conveying sheets, The apparatus includes a transport unit 5 that transports the separated sheet and a control unit 6 that controls electrical components of the sheet feeding device 1.

The sheet storage unit 2 includes a sheet feeding tray 101, a sheet guide frame 125, a sensor 115, and a sensor lever 114.
Etc. are provided. The paper feed tray 101 is for stacking sheets. The paper feed tray 101 is configured so that its vertical position can be adjusted so that the upper surface of the stacked sheets S is maintained at a predetermined height position. The position adjustment is performed by the control unit 6 controlling the rotation of a lifting tray motor (not shown) for raising and lowering the sheet feeding tray 101 in accordance with the detection results of the sensor 115 and the sensor lever 114 described later.

The sheet guide frame 125 is used to position the sheet S by abutting the end of the sheet S placed on the tray.

The sensor 115 and the sensor lever 114 are
This is for detecting the height of the upper surface of the sheet S placed on the sheet feed tray 101. The sensor lever 114 operates according to the height position of the upper surface of the sheet S, and the sensor 115 detects the operating state (the position of the sensor lever 114), so that the upper surface of the sheet S reaches a predetermined height position. Is detected. This sensor 11
The detection result (ON / OFF) of No. 5 is output to the control unit 6 and is used for adjusting the height position of the sheet feeding tray 101 described above.

The sheet sucking / conveying section 4 is for feeding the sheets stacked on the sheet feeding tray 101. The sheet suction / conveyance unit 4 includes a suction duct 7, a drive unit 8, a conveyance belt 106, and the like.

The transport belt 106 is disposed above the paper feed tray with the paper feed direction side slightly upward. The transport belt 106 is wound around a driving roller 130 and a driven roller 131, and is rotated in the direction of arrow B shown in FIG. Further, a suction hole 105 for sucking and sucking the sheet is formed on the surface.

The drive section 8 rotates the drive roller 130, and transmits the rotation of the DC motor 9 via the electromagnetic clutch 10 to operate the transport belt 106.

The DC motor 9 and the electromagnetic clutch 10 are controlled and controlled by the control unit 6. Suction duct 7
Is for sucking air through the suction holes 105 of the conveyor belt 106, and is arranged in the track of the conveyor belt 106. The relay duct 1 is drawn by the suction fan 11.
2. By suctioning the air through the suction duct 7, a negative pressure can be generated in the vicinity of the suction hole 105.

The relay duct 12 is provided with a suction valve 13 so that the air flow in the relay duct 12 around the shaft 14 can be controlled to be openable and closable.
A wire 15 is wound around the shaft 14 and a solenoid 16
The suction valve 13 is opened by applying a predetermined voltage to the suction valve 13. When the voltage applied to the solenoid 16 is turned off, the suction valve 13
Thereby, the relay duct 12 is closed. The suction fan 11 and the solenoid 16 are controlled by the control unit 6.

A suction sensor 18 as a photo sensor is provided in the suction duct 7, and detects that the uppermost sheet S 1 of the sheet S has been sucked to the transport belt 106 by a sensor lever 19. The sensor lever 19 can rotate about a shaft 19-a, and normally, as shown in FIG.
06 and below the transport belt 106 by its own weight,
It is protruding. When the uppermost sheet S1 is sucked, the sensor lever 19 is rotated into the suction duct 7, and by detecting this by the suction sensor 18, sheet suction is detected. When the uppermost sheet S1 is transported, the sensor lever 19 projects again below the transport belt 106. Note that the sensor lever 19 is preferably disposed between about 10 mm and 20 mm downstream from the leading end position of the sheet S1 shown in FIG. The suction sensor 18 is controlled by the control unit 6.

The separating section 3 blows air to the leading end of the sheet S to lift and separate the sheet S. The separating section 3 assists suction and conveyance of the sheet S and prevents double feeding.

The ejection duct 20 is arranged on the downstream side of the sheet feeding tray 101 in the sheet feeding direction and below the driving roller 130. The ejection duct 20 is provided with a separation nozzle 20a for ejecting air in the direction of arrow C in FIG. 1 and a separation nozzle 20b for ejecting air in the direction of arrow E in FIG.

The separation fan 21 is a fan that supplies air to the ejection duct 20 via the relay duct 22, and is controlled by the control unit 6.

The transport section 5 is for transporting the sheet fed by the sheet suction transport section 4 further downstream. Further, when two fed sheets are fed in a stack, a mechanism for separating the sheets one by one is included (details will be described later).

The transport section 5 comprises a movable path 23 movable in the direction of arrow D according to the sheet size, and transport rollers 24 provided downstream of the path. The movable path 23 includes a pull-out roller 25, a pull-out roller motor 26 which is a DC motor that rotationally drives the pull-out roller 25, an electromagnetic clutch 27 that couples a driving force, a movable transport path 28, a transport sensor 29, and a sensor lever 30. Have been. The transport roller 24 is fixed, and is driven by a transport roller motor 31 which is a DC motor. The transport sensor 29, the pull-out roller motor 26, the electromagnetic clutch 27, and the transport roller motor 31 are connected to and controlled by the control unit 6, respectively. Movable path 2
Numeral 3 is configured to be movable in the direction of arrow D by a motor (not shown) and drive transmission means, and the position of the movable path 23 can be controlled by the control unit 6.

The arrangement of the transport sensor 29, the pull-out roller 25, and the transport roller 24 in the sheet transport direction will be described later.

The control 6 comprises a CPU 32, a memory 33, a timer 34, an I / O port 35, a driver 36 and the like. The CPU 32 is connected to the electric components of the sheet feeding device 1 via the I / 0 port 35 and controls the sheet feeding operation. The transport roller motor 31, the pull-out roller motor 26, the DC motor 9, the suction fan 11, and the separation fan 21 are connected to the CPU 32 via the driver 36, and control the number of rotations of each motor according to the command of the CPU 32. it can.

The time from when the voltage is applied to the solenoid 16 until the suction signal of the sheet S1 is input to the suction sensor 18 (hereinafter, the suction time) and the time when the drive connection signal is input to the electromagnetic clutch 10 and the sheet S1 Is the transport sensor 2
A configuration is such that the time until the detection is performed by 9 (hereinafter referred to as “transport time”) is measured by the timer 34 and the data can be stored in the memory 33.

Next, the sheet feeding operation will be described step by step (FIGS. 4 to 6).

The control section 6 raises the sheet feeding tray 101 in accordance with the detection results of the sensor lever 114 and the sensor 115, thereby keeping the interval between the sheet suction and transport section 4 and the top sheet S1 of the sheet S constant. To feed the sheet, first, the suction fan 11, the separation fan 21, the DC motor 9,
The pull-out roller motor 26 and the transport roller motor 31 are operated. At this time, the electromagnetic clutches 10 and 27 do not receive the drive connection signal, and the transport belt 106 and the pull-out roller 25 do not operate. Further, the solenoid 16 does not receive an open signal of the suction valve 13, and the suction fan 11 does not make the inside of the suction duct 7 a negative pressure. The air supplied from the separation fan 21 passes through the ejection duct 20 and is ejected to the outside from the separation nozzle 20-a and the separation nozzle 20-b. By opening the suction valve 13, the uppermost sheet S <b> 1 of the sheet S floated by the separation nozzle 20-a has a negative pressure in the suction duct 7 and is attracted to the transport belt 106. The suction time at this time is stored in the memory 33 shown in FIG. When a suction signal is input to the suction sensor 18, a drive connection signal is input to the electromagnetic clutches 10 and 27, and the uppermost sheet S1 is transported. When the leading edge of the top sheet S1 reaches the transport sensor 29, the transport time required for the transport is measured and stored in the memory 33. At the timing when the leading end of the uppermost sheet S1 enters the pull-out roller 25, the voltage to the solenoid 16 is released, and the uppermost sheet S1 is released from suction by closing the suction valve 13.
The connection signal of 0 is turned off, and the transport belt 106 is stopped.

The uppermost sheet S1 is then removed from the drawing roller 2
5. It is transported downstream by the transport rollers 24. When the second sheet S2 (FIG. 5) of the sheets S is sucked, the time for the rear end of the uppermost sheet S1 to reach the leading end of the sheet S2 is determined by the CPU 32 based on the transport time of the uppermost sheet S1 stored in the memory 33. To predict. Then, the suction time of the uppermost sheet S1 stored in the memory 33 is subtracted from the predicted time, and the solenoid 16 is moved to the solenoid 16 so that the rear end of the uppermost sheet S1 and the front end of the second sheet S2 coincide. Input the release signal. And the sheet S2
Is attracted to the conveyor belt 106, when the rear end of the uppermost sheet S1 and the front end of the sheet S2 become, for example, about 5 mm,
The drive connection signal is input to the electromagnetic clutch 10 and the seat S
Convey 2.

In the same manner, on the third and subsequent sheets, the suction time and the transport time of the preceding sheet are measured, and the sheet feeding sequence for keeping the sheet interval small and constant is repeated.

The above-described paper feeding sequence assumes that the suction time of the preceding paper is the same as the suction time of the suction paper.
The paper feeding sequence for making the paper interval small and constant will be described next when the suction time of the suction paper is different from the suction time of the preceding paper (see FIG. 6).

1. When the suction time of the suction paper S2 is longer than the suction time of the preceding paper S1 (FIG. 6).

As described above, since the control is performed so that the rear end of the front paper S1 and the front end of the suction paper S2 are adjusted according to the suction time and the transport time of the front paper S1, the distance between the front paper S1 and the suction paper S2 is reduced. Will spread. In this case, in the CPU 32,
The difference between the suction time of the front paper S1 and the suction time of the suction paper S2 is measured, and D is set so that the space between the front paper S1 and the suction paper S2 is reduced.
The speed of the C motor 9 is increased for a predetermined time.

2. When the suction time of the suction paper S2 is shorter than the suction time of the preceding paper S1.

In this case, since the rear end of the front sheet S1 and the front end of the suction paper S2 are overlapped, the suction S2 is not fed immediately, and the rear end of the front paper S1 is suctioned due to the transport time of the front paper S1. A connection signal is input to the electromagnetic clutch 10 when the leading end of the sheet S2 is reached. At this time, the DC motor 9 does not need to increase or decrease.

Next, the sheet S1 is attracted to the transport belt 106, and the sheet S1 is not separated properly during transport.
A sequence in a case where the sheet S2 stacked under the sheet S1 is also fed (double feed) will be described.

The double feed described here is a case where the sheet S2 is fed by being dragged by the sheet S1 as shown in FIG. 7A, and the sensor of the sheet S2 and the leading end of the sheet S2 are shifted by a distance a. Assume the case of double feed.

While the sheet S is being conveyed, the interval between the sheets S1 and S2 is detected by the conveyance sensor 29, and whether or not the predetermined interval is always maintained is measured by the timer 34 and managed by the CPU 32. If the sheet interval is different from the predetermined value, when the leading edge of the sheet S1 enters the transport roller 24 and the trailing edge of the sheet S1 comes out of the pull-out roller 25, the transport roller 24 is increased / decreased to a predetermined paper. Control to be between. The transport sensor 29 detects the length of the sheet in addition to the interval between the sheets. If the length of the sheet S1 is longer than the sheet length of the sheet S1 set in advance, it is determined that the double feed as shown in FIG. 7A has occurred.

As shown in FIG. 7A, when the trailing edge of the sheet S2 reaches the transport sensor 29, the double feed is determined, and the leading edge of the sheet S1 is transferred to the transport roller 24 from the transport time of the sheet S1. When the rear end of the electromagnetic clutch 10
7, the driving connection signal of the sheet S2 and the sheet S2
Next, the next sheet (not shown) is stopped (FIG. 7B).
At this time, the overlap amount b between the sheet S1 and the sheet S2 is calculated based on the length L2 and the sheet length L1 obtained by the transport sensor 29 and recorded in the memory 33.

The sheet S1 is further conveyed to the downstream side by the conveying rollers 24, and when the overlap amount b stored in the memory is exhausted, a driving signal is applied to the electromagnetic clutches 27 and 10. Thereafter, the flow returns to the above-described sheet feeding and conveying operations. Next, the positional relationship among the transport roller 24, the pull-out roller 25, and the transport sensor 29 of the transport unit 5 will be described.

The distance c between the rollers is preferably, for example, about 10 mm shorter than the length L1 of the conveyed paper. If the roller-to-roller length c is further reduced, the rear end of the sheet S1 is pinched by the pull-out roller 25 when the sheet S2 shown in FIG.
The leading end of the sheet S2 is pinched by the transport roller 24, and the double feed correction cannot be performed. As described above, the movable path 23 operates before the start of sheet feeding, and the distance c between the rollers is L1-10 mm.
It is controlled to be in the position.

The distance d between the pull-out roller 25 and the conveyance sensor 29 is such that the sheet S2 is stopped after the conveyance sensor 29 detects the rear end of the sheet S2. Will be sandwiched between.

Accordingly, the distance d is set to a time, and is secured to be equal to or more than (connection time of the electromagnetic clutch 27) + (response time of the control unit 6) + (time required to convey the sheet by 10 mm (that is, L1-c)). There is a need to. (Electromagnetic clutch 27
Connection time) + (response time of the control unit 6) is about 30 ms, so that the transport speed is 100 mm / s to 1000 mm.
/ S is 3 mm to 30 mm in distance. Therefore,
The distance d is 40 by adding 10 mm (L1-c) to 30 mm.
mm or more.

The above is the description of the sheet feeding operation in the first embodiment.

In the first embodiment, the sheet feeder of the upper separation type in which the sheets are sequentially separated and fed from the uppermost sheet by the air separation type has been described. Needless to say, it can be implemented.

(Embodiment 2) Embodiment 2 is an image forming apparatus provided with the sheet feeding device of Embodiment 1. This will be described below with reference to FIG.

Image forming apparatus main body (hereinafter simply referred to as “apparatus main body”)
As shown in FIG. 8, an original mounting table (platen glass) 906, a light source 907, a lens system 908,
A paper feed unit 909, an image forming unit (image forming unit) 902, and the like are provided. Also, a document table (platen glass)
On 906, an automatic document feeder is installed.

A paper feeding unit 909 is provided with a cassette 91 in which recording sheets S are stored and which can be detachably attached to the apparatus main body 900.
0, 911, and a deck 913 arranged on the pedestal 912. Further, a feeding mechanism for feeding sheets (sheets) S stored in the cassette 910 or the like is provided. In the second embodiment, the sheet feeding device 1 in the first embodiment described above is employed as the sheet feeding mechanism.

The image forming section 902 includes a cylindrical photosensitive drum 914, a developing device 915, a transfer charger 916, a separation charger 917, a cleaner 918, a primary charger 919, and the like. Further, on the downstream side of the image forming unit 902, a transport device 920, a fixing device 904, a discharge roller pair 905, and the like are provided. The control device 930 controls and controls the entire image forming apparatus. In the second embodiment, the control device 930 also controls the sheet feeding operation by the sheet feeding unit 909.

The operation of the image forming apparatus will be described.

When an image formation start signal is output from control device 930, the automatic document feeder conveys the document through a predetermined conveyance path, and a document table (platen glass) 906.
This is placed on the upper predetermined position.

Thereafter, the image forming section 902 and the sheet feeding section 909 are driven at a predetermined timing.

The paper supply unit 909 includes cassettes 910 and 911
Alternatively, the image forming unit 902 can be
The sheet S is fed toward. The details of the feeding are as described in the first embodiment. Paper feed unit 90
The sheet S fed from 9 is corrected in skew by a registration roller 901, and is sent to the image forming unit 902 in timing with image formation described later.

On the other hand, the image forming unit 902 irradiates the light emitted from the light source 907 to the original D placed on the original placing table (platen glass) 906, and reflects the reflected light to the photosensitive drum 914 via the lens system 908. Irradiate. Photoconductor drum 91
4 is charged by the primary charger 919 in advance, so that the reflected light is incident thereon to form an electrostatic latent image on its surface. Next, the developing device 915 develops the electrostatic latent image to form a toner image.

The transfer charger 916 is connected to the photosensitive drum 91
4 is transferred to the sheet S sent. The separation charger 917 separates the sheet S on which the toner image has been transferred from the photosensitive drum 914 by charging the sheet S to a polarity opposite to that of the transfer charger 916.

The transport device 920 transports the separated sheet S to the fixing device 904. The fixing device 904 permanently fixes the transferred image on the sheet S. Finally, the discharge roller pair 905 transfers the sheet S on which the image is fixed to
It is discharged from the apparatus main body 900.

In the image forming apparatus of the second embodiment described above, it is possible to increase the speed of image formation without causing double feeding of sheets.

[0079]

As described above, the present invention (claim 1)
According to this configuration, the suction detection unit detects that the sheet material is sucked by the suction conveyance body, and based on the suction detection signal, starts moving the suction conveyance body for conveying the sheet material. Since the control is performed, the time (inter-paper time) from the time when the suction unit is operated to the time when the suction conveyance body is operated can be minimized. Thereby, when the sheet material is continuously fed and conveyed, inter-sheet feed can be realized without causing double feeding. That is, the frequency of jams is reduced by reducing the feeding delay or the double feeding, thereby improving the reliability of the sheet feeding device or the image forming apparatus equipped with the sheet feeding device. As a result, a good impression can be given to the user.

Further, a conveying speed measuring means for measuring a conveying speed of the sheet material between the suction conveying body and the sheet material conveying means is provided, and based on a suction detecting signal for the sheet material by the suction detecting means, A suction time calculating unit for calculating a suction time from when the suction of the sheet material is started by the suction means to when the sheet material is suctioned by the suction conveyance body, wherein the suction conveyance body and the sheet material conveyance means are provided; A time calculating unit for calculating a time at which the sheet material conveyed between the two passes through a predetermined position, a conveying speed measured by the conveying speed measuring unit, and a suction time calculated by the suction time calculating unit. A suction start timing calculation unit for calculating a suction start timing of the suction unit for the sheet material to be conveyed next based on the time calculated by the time calculation unit; In the case where a suction control unit for controlling suction by the suction unit is provided based on the suction start timing calculated by the suction start timing calculation unit (claim 2), a desired sheet interval with respect to the preceding sheet material is provided. Then, the next sheet material can be conveyed, so that the speed of sheet feeding is further promoted. Since the sheet feeding is performed while controlling the sheet material suction time and the transport time, stable paper feeding can be performed regardless of the type of paper used, the size, the folding, and the curl. Further, it is possible to stably feed paper that has been left under any environment. Further, since it has a sheet feeding sequence for maintaining a constant sheet interval and a function of correcting a double feed at the time of separation failure, it is possible to cope with an increase in the speed of the sheet feeding apparatus and the image forming apparatus.

Further, the sheet material conveying means has first and second pairs of conveying rollers capable of conveying and driving the sheet material arranged in a predetermined conveying direction. In the case where the transport drive speeds of the transport roller pairs are individually adjustable (claim 3), the transport drive speeds are individually adjusted even when the sheet material is double-fed to the sheet material transport means. This is advantageous because double feed can be eliminated by the adjusted first and second conveying roller pairs, and the sheet materials can be conveyed one by one. Furthermore, the arrangement interval of the first and second conveyance roller pairs can be changed freely (Claim 4), so that the first and second conveyance roller pairs can be arranged at an optimal arrangement interval according to the size of the sheet material. Is set, and the double feeding of the sheet material can be suitably eliminated.

In the case where the suction means is configured to perform suction by an air suction force (claim 5), the present invention is applied to an air feeding apparatus, and does not cause double feeding and causes a gap between small sheets. An excellent air feeding device capable of feeding paper is provided.

The image forming apparatus includes the sheet feeding device according to any one of claims 1 to 5, and includes image forming means for forming an image on a sheet material conveyed and fed by the sheet feeding device. The image forming apparatus according to the sixth aspect of the present invention exhibits each of the above-described effects and can minimize the sheet interval, thereby improving the productivity of the image forming apparatus. As a result, the effect of reducing the power consumption of the image forming apparatus and the time required for copying can be expected.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a sheet feeding device according to a first embodiment.

FIG. 2 is a top view of the sheet feeding device according to the first embodiment.

FIG. 3 is a front view of the sheet feeding device according to the first embodiment.

FIG. 4 is a cross-sectional view of the sheet feeding device according to the first embodiment and is an explanatory diagram of a sheet feeding operation.

FIG. 5 is a cross-sectional view of the sheet feeding device according to the first embodiment, illustrating the sheet feeding operation.

FIG. 6 is a sectional view of the sheet feeding device according to the first embodiment and is an explanatory diagram of a sheet feeding operation.

FIG. 7 is a cross-sectional view of the sheet feeding device according to the first embodiment, and is a simplified cross-sectional view of a transport unit.

FIG. 8 is a cross-sectional view of an image forming apparatus including the sheet feeding device according to the first embodiment.

FIG. 9 is a cross-sectional view of a sheet feeding device according to the related art.

FIG. 10 is a top view of a conventional paper feeding apparatus.

[Explanation of symbols]

 4 Suction / Conveying Unit 5 Conveying Unit 8 Drive Unit 18 Suction Sensor 29 Conveying Sensor 32 CPU 34 Timer 101 Paper Tray 106 Conveying Belt

Claims (6)

[Claims] 1. A sheet material stacking means capable of stacking a plurality of sheet materials, a suction means capable of sequentially sucking the sheet materials stacked on the sheet material stacking means, and a sheet material sucked by the suction means. A suction conveyance unit having a freely movable suction conveyance body that can be adsorbed, and a sheet material capable of receiving the sheet material sucked and conveyed by the suction conveyance unit and conveying the sheet material in a predetermined sheet feeding direction. A sheet feeding device comprising: a conveyance unit; a suction control unit configured to detect suction of a sheet material by the suction conveyance unit; a conveyance control unit configured to control a movement driving of the suction conveyance unit; A conveyance control unit that controls, based on a suction detection signal for the sheet material by the suction detection unit, to start moving and driving the suction conveyance body for conveying the sheet material; Sheet feeding apparatus according to claim. 2. A device according to claim 1, further comprising: a conveying speed measuring unit configured to measure a conveying speed of the sheet material between the suction conveying body and the sheet material conveying unit. A suction time calculating unit for calculating a suction time from when suction of the sheet material is started by the suction means to when the sheet material is sucked by the suction conveyance body, wherein the suction conveyance body and the sheet material conveyance means are provided; Providing a time calculation unit that calculates the time when the sheet material conveyed between has passed a predetermined position, the conveyance speed measured by the conveyance speed measurement unit, and the suction time calculated by the suction time calculation unit A suction start timing calculation unit that calculates a suction start timing of the suction unit with respect to a sheet material to be conveyed next based on the time calculated by the time calculation unit; Based on the suction start timing calculated by the pull start timing computing unit, wherein is provided a suction control section that controls the suction by the suction means, the sheet feeding apparatus according to claim 1, wherein a. 3. The sheet material transporting means has a first and a second transport roller pair capable of transporting and driving a sheet material arranged in a predetermined transport direction. The paper feed device according to claim 1, wherein the transport drive speed of the transport roller pair is individually adjustable. 4. The paper feeder according to claim 3, wherein the arrangement interval between the first and second transport roller pairs is changeable. 5. The paper feeding apparatus according to claim 1, wherein said suction means performs suction by an air suction force. 6. An image forming means, comprising: the sheet feeding device according to claim 1; and forming an image on a sheet material conveyed and fed by the sheet feeding device. An image forming apparatus comprising: