JP3021461B2 - Refeeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an image forming apparatus, such as a copying machine or a printer, which prints an image on one side and stacks it on a re-feed tray once by air. The present invention relates to a sheet re-feeding device which floats the sheet by spraying the sheet, presses the lowermost sheet against the conveying means by a suction force, and re-feeds the sheet to the image forming section.

[Conventional technology]

As described in, for example, Japanese Patent Application Laid-Open No. 56-56442, a sheet feeding device floats sheets stacked on a tray by blowing air from an air knife, and conveys the lowest sheet by suction. The paper feeder using air, which separates the paper on top of the paper by pressing it against the paper and feeds the paper in order from the lowest, feeds the paper using a pick-up roller that repeats ascending and descending each time paper is fed. Attention has been paid to the fact that the paper feeding speed can be increased as compared with a paper device.

In general, such a paper feeder using air has the highest wind speed of air blown from an air knife when the number of sheets on a tray is large, and is slower in several stages as the number of sheets is reduced. The wind speed is switched so that even when the number of sheets becomes a small number, the wind speed that can float and separate the lowermost sheet from the lowermost sheet on the tray is always given to the end of the sheet.

[Problems to be solved by the invention]

However, such a paper feeding device using air is used for a re-feeding device used for performing double-sided copying or composite copying of a copying machine, for example, and the entire number of sheets to be copied on the re-feeding tray is used. If re-feeding is started after stacking paper (transfer paper), even when the number of sheets on the re-feed tray gradually decreases and reaches a small number, Is constantly blown at a wind speed just enough to levitate it, so it vibrates up and down (dancing fluttering) due to the air blown
However, it takes time for the lowermost sheet to be pressed against the conveying means by the suction force.

Therefore, if the transport speed of the transport unit is too short by shortening the paper transport interval of the transport unit, the transport unit may start transporting before the paper is pressed against the transport unit by the suction force. As a result, there is a disadvantage that the conveying speed cannot be increased much, even though the sheet feeding device uses the air with a bent angle.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and even if the number of sheets on the re-feeding tray is a small number, the sheet is promptly transferred to the conveying means by suction without vibrating up and down. An object of the present invention is to enable a sheet to be reliably conveyed at a high speed without being pressed and causing non-feeding.

[Means for solving the problem]

In order to achieve the above object, the present invention conveys a sheet on which an image is formed on one side and discharges the sheet onto a re-feeding tray, and the sheet discharging roller on the re-feeding tray. Air blowing means for blowing air to the end to float at least the lowermost sheet to the sheet above it; conveying means for re-feeding the sheet on the re-feeding tray to the image forming section; A re-feeding device provided with a suction means for pressing the lowermost sheet on the re-feeding tray by a suction force, wherein a reverse roller and a feed roller pressed against each other are provided on the downstream side of the transporting means. When only one sheet is conveyed from the re-feeding tray by the conveying means, a reverse roller rotates with the feed roller rotating in the re-feeding direction, and the conveyed sheet is multi-fed. When the reverse roller rotates in the opposite direction to the rotation direction, a separating / transporting unit is provided for returning the multi-fed sheet from the reverse roller side and separating and transporting the sheet into one sheet. When the stack number of sheets discharged onto the re-feed tray reaches a preset small number,
There is provided a wind speed switching means for switching the air speed of the air blowing means for blowing the edge of the paper to zero wind speed at which the paper does not float.

(Operation)

When the number of sheets discharged onto the re-feeding tray reaches a predetermined small number, the wind speed switching means blows the end of the sheet by the air blowing means. Since the air velocity is switched to zero, where the paper does not float, the paper on the re-feeding tray is quickly pressed against the transport means by the suction force of the suction means without vibrating up and down even if it becomes a small number of sheets. Is transported without causing non-feeding.

Then, when the conveying means multi-feeds the sheets, the separating / conveying means including a reverse roller and a feed roller provided on the downstream side of the conveyance separates and conveys the sheets into one sheet, so that the sheets are multi-fed. It can be transported without any trouble.

〔Example〕

Hereinafter, a specific description will be given based on an embodiment of the present invention.

FIG. 1 is a schematic configuration diagram showing an example in which a refeeding device according to the present invention is applied to a copying machine, and FIG. 2 is an overall configuration diagram showing an entire copying machine provided with the refeeding device.

As shown in FIG. 1, the refeeding device 10 conveys a sheet P, which is a transfer sheet having an image formed on one side (upper side), and discharges the sheet P onto the refeeding tray 1. The air is blown to the paper discharge roller 3 rotating at a time and the end portion Pa which is the leading end when the paper P discharged to the paper re-feed tray 1 is re-fed, so that at least the lowermost paper is printed on the paper above it. Air knives 5 as air blowing means for floating the paper P, conveying means 6 for re-feeding the paper P on the re-feeding tray 1 to an image forming section described later in FIG. A suction means 7 for pressing the lowest sheet on the paper feed tray 1 by a suction force;

The re-feeding device 10 includes a separating / transporting unit that separates and transports the sheet P transported from the re-feed tray 1 by the transporting unit 6 downstream of the transporting unit 6.
50, and when the number of stacks of paper P discharged onto the re-feeding tray 1 reaches a preset small number, for example, 10 (preferably set to about 5 to 15), At the end Pa of P, there is provided a wind speed switching means 60 for switching the wind speed of the air from the air knife 5 to be blown in the direction of arrow I in FIG.

The paper re-feeding device 10 contacts the upper surface of the paper P discharged from the paper discharge roller 3 and always rotates the paper feed roller 8b provided in the paper discharge path 28 when the paper feed roller 8b is rotating. A feed roller 9 that rotates by being brought into contact with the roller and conveys the sheet P so as to abut against the end fence 4.
Is provided above the re-feeding tray 1 so as to be rotatable in the direction of arrow A in FIG.
And protrudes downward from the lower surface of the paper guide plate 12 mounted above the paper guide plate.

Further, the re-feeding device 10 is arranged such that the rear end of the paper P discharged onto the re-feed tray 1 by the discharge rollers 3 (the rear end side at the time of re-feeding after completion of the stacking in FIG. 1). Right part) Pb
Trailing edge guide member 11 that guides while holding the paper from above
1 is swingably attached to the left side of a horizontal portion 4a extending substantially in parallel with a predetermined interval above the refeed tray 1 of the end fence 4 and is attached together with the end fence 4 in the arrow of FIG. It is possible to move in the direction C shown.

The paper trailing end guide member 11 is formed, for example, by slightly bending a stainless steel round bar substantially at the center to form a C-shape. A pair of them is provided at predetermined intervals in the paper width direction perpendicular to the direction of arrow B, so that the vicinity of both ends of the paper is lightly reduced by its own weight.

The separating / transporting means 50 comprises a reverse roller 13 and a feed roller 32 (see also FIG. 3) which are pressed against each other in the vertical direction, and the reverse roller 13 constantly rotates in a direction indicated by an arrow D in FIG. The rotational urging force from the shaft is constantly applied in the direction of arrow D via the known torque limiter 20, and one sheet P is re-fed in the direction of arrow E from above the refeed tray 1. Occasionally, the sheet P is rotated in the direction opposite to the arrow D following the feed roller 32 rotating in the direction indicated by the arrow F. Return the paper from top to bottom.

The reverse roller 13 is provided substantially at the center of the sheet P on the re-feeding tray 1 in the sheet width direction, and the feed roller 32 is correspondingly fixed to the shaft 14 to which the roller 26 on the left side of the conveying means 6 is fixed. It is attached to the approximate center of one via a one-way clutch.

In FIG. 1, reference numeral 37 denotes a sensor (for example, a transmission type photo sensor) which detects a sheet P re-fed in the direction of arrow E from above the re-feeding tray 1.

In FIG. 1, reference numeral 27 denotes a branching claw, which is used to move the transport path of the sheet P transported from the left through a fixing device, which will be described later, to a discharge path.
28 and a re-feeding conveyance path 35 for guiding to the re-feeding tray 1 used in the double-sided copy mode. When it is at the position shown in the figure, the conveyance path is set to the discharge path 28 side, and each is in the direction of the arrow. The paper P is transported rightward by the rotating transport rollers 29a, 29b and 8a, 8b.

Next, an entire copying machine provided with the re-feeding device 10 will be described with reference to FIG.

The copying machine includes a copying machine main body 30 and an automatic document feeder (hereinafter, abbreviated as "ADF") 40. A refeeding device 10 is provided at the upper right portion inside the copying machine main body 30. Is arranged.

The copying operation of the copying machine is started by setting necessary copying conditions from an operation unit provided in the copying machine main body 30 and pressing a print button.

Here, the ADF 40 is provided with a document tray 201,
The document placed on the document tray 201 is fed by a document feed belt, and is conveyed onto a contact glass 101 through a document conveyance path 203.

After the original is conveyed onto the contact glass 101, the flash lamp 102 emits light at a predetermined timing, and the entire surface of the original is illuminated at one time. The power supply 103 of the flash lamp 102 is provided with a capacitor for charging the electric charge.

The reflected light from the original is transmitted through the first mirror 104 and the through lens 10.
5. The belt photoreceptor 107 serving as an image forming unit is exposed through the second mirror 106.

The belt photoreceptor 107 is uniformly charged by a charger 108, and forms an electrostatic latent image by exposure. The electrostatic latent image on the belt photoreceptor 107 is developed by the developing unit 110 after the unnecessary portion of the charge is removed by the eraser 109. The developed document image is transferred to the transfer section by a transfer charger.
The image is transferred to the sheet P by 111.

The paper P is fed from one of the paper feed trays 112, 113, 114 or the re-feeding device 10, and
The sheet is fed to the conveyance path 115 through a sensor 121 for detecting a sheet to be fed, which is provided immediately after the separation roller disposed in each of the stages 3,114, and is sent to the transfer section by the registration roller 116 in synchronization with the original image. Conveyed.

Then, the sheet P on which the image is formed is transferred to the transport belt 117.
When the duplex copy mode is selected after the fixation (if the combined copy is possible, the same is true), the sheet is guided by the branch claw 27 and re-fixed. The sheet is temporarily stacked on the re-feed tray 1 of the sheet feeding device 10, and is transported to the output tray 119 when the normal one-sided copy is selected or to the output port 120 when the collating device is installed. It is.

The document on the contact glass 101 is sent out after light irradiation (exposure) is completed by the document conveying belt 204, and is returned to the document tray 201 again by the document discharge roller 205.

Next, the structure of the sheet re-feed tray 1 and its peripheral components will be described.

The refeed tray 1 is formed with a paper stack portion surrounded by three sides by an end fence 4 and a pair of side fences (not shown), and a discharge roller 3 (FIG. 1).
Edges and the leading edge (which is the trailing edge at the time of re-papering) of the paper P discharged from the paper tray are guided by the side fences and the end fences 4, respectively, to a predetermined position suitable for re-feeding the paper stack. Position the paper P.

On the opposite side of the end stack of the paper stack (first
(Left side in the figure), a large opening is formed, and a conveying means 6 is provided therein.

The transport means 6 includes rollers 33 and
26 (see FIG. 1) are fixed to the shafts 34 and 14 at intervals of four (which can be increased or decreased as necessary), and four endless belts 44 are stretched between them. A number of small holes are formed in each endless belt 44, and a vacuum tank 45 is mounted in the endless belt 44.

Then, as shown in FIG. 1, the upper surface 44b serving as the conveying surface of the endless belt 44 is set to a height substantially matching the upper surface (stack surface) of the re-feed tray 1, and
A number of small holes 45a are formed at positions corresponding to the endless belts 44 on the upper surface of the backing 45, and the backing tank 45 is connected via a duct 46 as shown in FIG. (Not shown) when driving the tank
The lowermost sheet P in the sheet stacking section of the re-feed tray 1 is pressed against the endless belt 44 by the suction force generated in the inside 45.

The vacuum fan generates a suction force acting in the direction of arrow G in FIG. 1 in the vacuum tank 45 when a drive motor (not shown) is rotated.

In this embodiment, the bakyumu tank 45 and the duct 46
And a drive motor (not shown) for rotating the fan, which is not shown,
It corresponds to the suction means 7 for pressing the lowermost sheet by the suction force. The air knife 5 is provided in front of the sheet re-feed tray 1 as shown in FIG. 1, and the air discharged from an air knife fan (not shown) is sent there.

The fan for air knife and the fan for vacuum of the suction means 7 are driven by different drive motors.

As shown in FIG. 1, the air knife 5 is disposed close to an end Pa which is the leading end when the sheets P stacked on the sheet re-feeding tray 1 are re-supplied. The air discharged from the discharge port 5a formed by the air knife fan is blown toward the space between the sheet P and the upper surface of the re-feeding tray 1 to be sucked by the suction means 7 to the endless belt 44. The paper on the lowermost paper is levitated.

FIG. 4 is a longitudinal sectional view showing the detailed shape of the feed roller 9.

The feed roller 9 has roller portions 9a and 9b at both ends and a narrow portion 9c having a reduced diameter at a center portion. A hollow inner tube 53 is fitted into a hole 9d formed in the axial direction. It is united by gluing. Then, bearings 54, 54 are integrally fitted into both ends of the inner tube 53, a shaft 55 is fitted into the bearings 54, 54, and E-rings 57, 57 for retaining are attached to both ends, respectively. , The feed roller 9 is rotatably supported.

Then, both ends of the shaft 55 are fitted into bearing grooves 56a of a bracket 56 fixed to a device fixing portion above the re-feeding tray 1 as shown in FIG. And the shaft 55 is moved by the leaf spring 58 to the conveying roller 8b.
Side, and the small-diameter portion 9c of the feed roller 9 is
, So that the feed roller 9 rotates in the direction of arrow A following the rotation of the transport roller 8b in the direction of arrow.

As the material of the feed roller 9 suitable rubber material (e.g., foamed chloroprene rubber, EPDM, etc.), a fourth that each roller portion 9a as shown in FIG., Each corner portion R ₁ to R ₄ are rounded 9b (chamfering ) Is preferably applied so as not to damage the paper P.

The transport speed (linear speed) of the feed roller 9 is set slightly higher than the transport speed of the paper discharge rollers 3.

FIG. 5 shows a mechanism for moving the end fence 4 in the paper discharging direction. Two guide rods 61 are arranged in parallel at a predetermined interval along the paper discharging direction indicated by arrow B. The ends thereof are fixed by supporting plates 62 and 63, respectively, and guide blocks 59 and 59 (most clearly shown in FIG. 1) fixed to the bottom surface of the end fence 4 are passed through the respective guide rods 61 and 61. Therefore, they are engaged and can be moved in the direction indicated by the arrow B and in the opposite direction.

Further, pulleys 64 and 65 are rotatably provided at a position passing through the approximate center of the end fence 4 in the paper width direction at intervals in the left-right direction, and an endless timing belt 71 is stretched between the pulleys 64 and 65. Then, one portion of the timing belt 71 is fixed to the bottom of the end fence 4 by a fixing bracket 66.

Then, a drive gear 69 fixed to the rotating shaft of a stepping motor 68 is engaged with a gear 64a integral with the drive-side pulley 64 via an idle gear 67, and the stepping motor
By rotating 68 in both the forward and reverse directions with the number of pulses corresponding to the paper size, the end fluence 4 is moved in the left-right direction in FIG. 5 so that it can be moved to the optimum position suitable for each paper size.

In FIG. 5, reference numeral 72 denotes a home position sensor which is, for example, a transmission type photo sensor.
Is located at the home position (the left side in the figure), the light shielding plate 73 fixed at the lower part is detected.

In this refeeding device, when the refeeding tray 1 shown in FIG. 1 is stacked, air having a wind speed corresponding to the number of stacks is blown from the discharge port 5a of the air knife 5 to the end Pa of the paper P. The paper P is stacked at a predetermined stack position.

Then, when, for example, all 100 sheets P instructed to perform double-sided copying have an image formed on one side and are stacked on the re-feeding tray 1, re-feeding is started by the re-feeding device 10. You.

That is, air is blown from the discharge port 5a of the air knife 5 at a high speed to the end portion Pa of the paper P, and at the same time, the re-feeding tray 1 is moved by the suction force acting in the direction of arrow G in FIG.
The lowermost sheet on the upper side is pressed against the upper surface 44b of the endless belt 44, and the sheet thereon is levitated and separated.

In this state, the roller 26 of the endless belt 44 is driven at a predetermined paper feed timing in the direction indicated by the arrow F in FIG. 1, and only the lowermost sheet P is sent to the left by the endless belt 44. By the feed roller 32, the transport path 115 (second
(Fig.).

In this way, the sheets P stacked on the re-feeding tray 11 are re-supplied sequentially from the lowest sheet.
Each time the paper P is fed, it is detected by the sensor 37 and counted.

When the count value reaches 90 (the number of sheets on the re-feed tray 1 is 10), the wind speed of the air knife 5 becomes zero.

When the number of sheets becomes 10 or less, the sheets are not floated and are frequently fed. In this case, the reverse roller 13 is moved in the direction of arrow D in FIG. The paper is rotated to return to the re-feed tray 1 from the upper sheet and is separated into one sheet. Therefore, even if the number of sheets becomes a small number, the separation is surely performed.

Therefore, even if the number of sheets on the re-feed tray becomes a small number of about 10 sheets as in the past, if the wind velocity is sufficient to float the sheets, the sheets are By vibrating vertically (dancing fluttering) due to the air, it takes time for the lowest-order paper to be pressed against the conveyance means by the suction force, and the conveyance interval of the paper by the conveyance means is shortened. When speeding up is attempted, the conveyance means starts conveyance before the paper is sucked, which causes a disadvantage that non-feeding occurs.
The refeeder 10 does not have such a case.

By the way, as shown in FIG. 1, the paper P having an image formed on one side and passing through the fixing device 118 is liable to have a back curl in which both ends are curled toward the back side where no image is formed.

Accordingly, when the sheets are stacked on the re-feed tray 1 in a state where the central portion of the sheets P is swollen upward as described above, the sheets P which are subsequently discharged at a stage equal to or less than the original number of stacks. ′ Is pressed against the paper guide plate 12 by the previous paper P already stacked in a curled state,
Since the sheet is lifted to the side where it is further pressed by the air blown from the air knife 5, the sheet cannot be smoothly transported to a predetermined position because it cannot be discharged smoothly, and the sheet buckles to deteriorate the stacking property. When the sheet is re-fed, non-feeding or double feeding of the sheet is likely to occur.

However, in the re-feeding device 10 according to this embodiment, the first
As shown in the figure, the paper P 'discharged by the paper discharge roller 3 and guided by the lower surface of the paper guide plate 12 is partially protruded downward from the paper guide plate 12 in the direction of arrow A. The paper P 'is conveyed by the rotational conveying force of the feed roller 9 rotating until the end abuts on the end fence 4, so that the paper P' is not buckled at the time of stacking and the paper P ' The sheet is reliably conveyed to a predetermined upper position and stacked.

Further, in the re-feeding device 10, the sheet P discharged onto the re-feeding tray 1 by the sheet discharging roller 3 has a rear end Pb which is the rear end side at the time of re-feeding after stacking. While being guided by the paper trailing end guide member 11, the paper P is held down while being held down toward the re-feeding tray 1 side, so that the discharged paper P does not get caught in the rear end Pb by curling or the like. Since the position is securely stacked, no non-feed occurs.

Further, since the end fence 4 is movable in the direction of arrow C in FIG. 1, if a paper size is selected in advance by an operation unit provided in the copying machine main body 30, it is suitable for the selected paper size. Move to the new position each time.

Although the embodiment in which the present invention is applied to the refeeding device of the copying machine has been described above, the present invention can be similarly applied to other image forming apparatuses such as a printer.

〔The invention's effect〕

As described above, according to the present invention, even if the number of sheets on the re-feeding tray is a small number, the sheet is quickly pressed against the conveying means by the suction force without vibrating up and down. Even if the paper is transported at a high speed, it can be transported reliably without any non-feed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example in which a re-feeding device according to the present invention is applied to a copying machine, FIG. 2 is an overall configuration diagram showing an entire copying machine provided with the re-feeding device of FIG. FIG. 4 is a side view showing the structure of the re-feed tray 1 and its peripheral parts. FIG. 4 is a longitudinal sectional view showing the detailed shape of the feed roller 9, and FIG. It is a top view which shows the mechanism which moves. DESCRIPTION OF SYMBOLS 1 ... Re-feed tray, 3 ... Discharge roller 5 ... Air knife (air blowing means) 6 ... Transport means 7, 7 ... Suction means 10 ... Re-feeding device, 11 ... Paper rear end guide Member 30 Copy machine body 40 Automatic document feeder (ADF) 50 Separation / conveyance means 60 Wind speed switching means 107 Belt photoconductor (image forming unit) P Paper (transfer paper) , Pa …… end

Claims (1)

(57) [Claims] A sheet discharge roller for conveying a sheet having an image formed on one side thereof and discharging the sheet onto a re-feeding tray, and blowing at least air onto an end of the sheet discharged onto the re-feeding tray. Air blowing means for floating the sheet on the lowermost sheet, conveying means for re-feeding the sheet on the re-feeding tray to the image forming section, and A re-feeding device having suction means for pressing the lowest sheet of paper by suction force, comprising a reverse roller and a feed roller pressed against each other on the downstream side of the conveyance means. When only one sheet is conveyed from the re-feeding tray, the reverse roller follows the feed roller rotating in the re-feeding direction, and when the conveyed sheet is multi-fed, the reverse And a separating / transporting means for rotating the roller in a direction opposite to the co-rotating direction, returning the multi-fed sheet from the reverse roller side to separate and convey it into one sheet, and When the number of sheets of paper discharged onto the tray reaches a preset small number, a wind speed switching means is provided for switching the air velocity of the air blowing means for blowing the end of the paper to a wind velocity at which the paper does not float to zero. A sheet re-feeding device, characterized in that: