JP3482267B2 - Corner claw separation paper feeder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding means for coming into contact with the uppermost sheet of stacked sheets and feeding it, and a sheet of the sheet brought into contact with the front edge of the fed sheet. The present invention relates to a corner claw separating / feeding device having a separating claw for separating into two.

[0002]

2. Description of the Related Art For example, a sheet feeding device of an image forming apparatus such as a copying machine is provided with a sheet feeding roller which comes into contact with the uppermost sheet stacked in a sheet feeding cassette to feed the sheet. 2. Description of the Related Art There is a corner claw separation type sheet feeding device including a separation claw for separating sheets, which is disposed at at least one corner of a front edge of a stacked sheet in a sheet feeding direction.

[0003]

Such a corner claw separation type sheet feeder is a roller separation device in which, for example, another pair of rollers are brought into pressure contact with each other and one roller is given a reverse rotational force with a predetermined torque. The number of parts is smaller than that of the system and the cost can be reduced, but since the mechanism for separating the paper causes the paper itself to buckle, the buckling is sufficiently performed in the case of a high-speed machine with a high transport speed. Since the paper is fed before being fed, there is a problem that the portion of the paper that is caught by the separation claw is damaged. Therefore, the corner claw separating / feeding device using such a separating claw has been mainly used so far mainly for low-speed machines.

On the other hand, in the sheet feeding device of the image forming apparatus, as described in, for example, Japanese Unexamined Patent Publication No. 5-278880, the conveying speed by the half-moon-shaped sheet feeding roller is set to a low value at the start of feeding the sheet. And then there is one that is made to become gradually faster. In this paper feeding device, a pulley is eccentrically fixed to a shaft that supports a paper feeding roller, and a belt is also provided between the pulley and the pulley that is also eccentrically fixed to the support shaft in correspondence with the pulley. As described above, the feeding roller is wound around and the belt is rotated, so that the feeding roller is set at a low speed at the start of feeding the paper according to the amount of eccentricity of the pulley, and then the speed is gradually increased.

It is also described that the conveyance speed of the paper feed roller can be changed by using a set of gears which are eccentric with respect to the support shaft, instead of the pulley. By using this paper feeding device, even in the case of a high speed machine having a high carrying speed, the paper can be slowed until the buckling of the paper is completed. However, in the case of this paper feeding device, a pair of pulleys eccentric to the support shaft, a belt stretched between the pulleys, a pair of gears, and the like are required, so that the number of parts is increased. There was a problem that became complicated.

The present invention has been made in view of the above problems, and even if a corner claw separating / feeding device which is low in cost is adopted, the leading edge of the sheet in the feeding direction is damaged. The purpose is to be able to handle even high-speed machines. It is another object of the present invention to provide the corner claw separating / feeding device with a simple structure having a small number of parts.

[0007]

In order to achieve the above object, the present invention is directed to a corner claw separating / feeding device as described above, in which the separation claw separates the sheets fed by the sheet feeding means. Until that time, the conveyance speed changing means is provided to make the conveyance speed of the paper by the paper feeding means slower than the paper conveyance speed at the time of transferring the image onto the paper, and
The speed changing unit controls the amount of paper fed by the paper feeding unit.
After the separation with the release claw is completed,
After making it faster than the paper transport speed when transferring an image to paper
In addition, a means for adjusting the sheet conveying speed is provided.

[0008] In addition, in the above-mentioned corner claw separation feeder
Then, the sheet feeding means may have a sheet feeding roller eccentrically attached to the drive shaft, and the drive shaft may rotate at a constant speed.

[0009]

According to the corner claw separating / feeding device thus configured, even if the corner claw separating / feeding method using the separating claw is adopted in a high speed machine having a high conveying speed, the sheet is conveyed by the paper feeding means. The speed is slower than the sheet conveying speed when the image is transferred onto the sheet until the sheet fed by the sheet feeding means is separated into one sheet by the separating claw, so that the sheet is sufficiently seated by the separating claw. Since the paper can be fed after being bent and securely separated, there is no possibility of damaging the portion of the paper that is caught by the separation claw.

Further, after the separation of the sheet fed by the sheet feeding means by the separating claw is completed, the conveying speed of the sheet is made faster than the sheet conveying speed at the time of transferring an image on the sheet, and then the sheet conveying speed. By doing so, the number of image formations that can be processed per unit time, which has been reduced due to the delay at the start of paper feeding, is set to the conveyance speed when the image is transferred onto the paper at the conveyance speed after the completion of separation of the paper. You can increase it again by making it faster than speed,
High-speed processing can be maintained.

Further, in the corner pawl separating / feeding device having the paper feeding means and the separating pawl, the paper feeding means has a paper feeding roller mounted eccentrically with respect to the drive shaft, and the drive shaft is equidistant. If it is rotated at a high speed, the conveyance speed of the paper by the paper feed roller is kept constant until the fed paper is separated by simply rotating the drive shaft at a constant speed without providing a special speed changing mechanism. It is possible to make the transfer speed slower than the transfer speed at which the image is transferred onto the paper, and then increase the transfer speed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 3 is a schematic configuration diagram of a laser printer equipped with a corner claw separation sheet feeder according to an embodiment of the present invention. In this laser printer, a photoconductor drum 22 is provided substantially in the center of the apparatus main body 1 so as to be rotatable in the direction of arrow E,
A charging charger 23, a developing unit 25, a transfer charger 26, a separation charger 27, a cleaning unit 29 and the like are arranged around it.

The photoconductor drum 22 is irradiated with laser light output from the laser writing device 3, and the surface thereof uniformly charged by the charging charger 23 is exposed to correspond to a recorded image. An electrostatic latent image is formed.
Then, by rotating the photosensitive drum 22 in the direction of the arrow E, the portion on which the electrostatic latent image is formed is the developing unit 25.
After passing through, the toner is attached to form a toner image (visualized image).

On the other hand, the sheets P are fed one by one from the inside of the sheet feeding cassette 33 of the corner claw separation sheet feeding device 10 by the sheet feeding rollers 14 and 15, which is a pair of registration rollers 37.
It is temporarily stopped in the state of contacting with, and is conveyed toward the transfer portion provided with the transfer charger 26 at a timing synchronized with the toner image on the photosensitive drum 22.

Then, on the paper P, the photosensitive drum 22
The upper toner image is transferred by the transfer charger 26,
It is separated from the photoconductor drum 22 by the separation charger 27, and is conveyed by the conveyance belt 31 to the fixing unit 32 having a built-in heater, where the toner image is heated and pressure-fixed. After that, the paper P is discharged onto the paper discharge tray 2 provided in the upper part of the apparatus main body 1.

Corner claw separating / feeding device 1 for feeding paper
0 is the bottom plate 13 in the paper feed cassette 33 as shown in FIG.
Is provided so as to be rotatable around the support pin 35 in the direction of arrow A. Then, the front end side of the paper P in the paper feeding direction is placed on the bottom plate 13. Above the leading edge of the paper P,
Paper feed rollers 14 and 1 which are paper feed means that come into contact with the uppermost portion of the paper P stacked on the bottom plate 13 and feed the paper P.
5 are fixed to the shaft 16 at intervals along the axial direction as shown in FIG.

On both sides of the paper feed cassette 33, a pair of side guides 1 for controlling the positions of both side edges of the paper P stacked on the bottom plate 13 in the paper width direction orthogonal to the paper feed direction.
7, 18 are arranged so that they can approach and separate from each other. Further, in the rear center of the paper feed cassette 33, the paper P
A back fence 19 that regulates the position of the rear end portion of the sheet in the paper feeding direction is provided so as to be movable and adjustable in the arrow B direction.

At the tip ends of the pair of side guides 17 and 18, as shown in FIG.
Separation claws 41 and 42 are swingably attached by attachment pins 43 so as to be respectively located at corners on both sides of the front edge of the sheet P stacked above in the transport direction.
As shown in FIG. 4, triangular paper-sheet pressing portions 41a and 42a are formed at one ends of the separating claws 41 and 42, respectively, and the paper-sheet pressing portions 41a and 42a are
It is adapted to hang on the corner of the leading edge side of the paper P.

The paper feed rollers 14 and 15 each have a half-moon shape in which a part of the peripheral surface is linearly cut, and the shaft 16 has a shaft 16 shown in FIG.
By rotating in the direction of arrow C, it rotates in the same direction. A spring 45 is interposed between the bottom plate 13 and the bottom surface of the paper feed cassette 33, and the bottom plate 13 is pushed up by the urging force of the spring 45, so that the bottom plate 1
The uppermost sheet P stacked on the sheet 3 is the peripheral surface 14a, 15a of the sheet feeding roller 14, 15 (see also FIG. 4).
In addition, it is possible to press-contact with a pressure suitable for paper feeding. As shown in FIG. 2, when the linear cutouts 14b and 15b of the paper feed rollers 14 and 15 face the paper surface of the paper P on the bottom plate 13, the paper P is prevented from further rising. Therefore, the paper feed rollers 14 and 15 are separated from the paper P.

The corner claw separating / feeding device 10 separates the sheets fed by the feed rollers 14 and 15 into separating claws 41 and 4.
The conveyance speed V1 of the paper until it is separated into one by 2
As shown in FIG. 5, it is set lower than the sheet conveying speed V2 when the image is transferred onto the sheet. The control is performed by the control device 50 shown in FIG. That is, in this embodiment, the control device 50 determines the conveyance speed of the paper until the paper fed by the paper feeding means is separated into one sheet by the separation claw from the paper conveyance speed at the time of transferring the image to the paper. It functions as a conveyance speed changing means for slowing down.

The control unit 50 has a central processing unit (CPU) having various judgment and processing functions and a sheet conveying speed V1 until the fed sheets are separated into one sheet by the separating claws 41 and 42. Paper transport speed V when transferring an image
2 A ROM that stores each processing program including programs necessary for slowing down and fixed data, a RAM that is a data memory that stores the processing data, and an input / output circuit
(I / O).

The control device 50 inputs various signals from various sensors provided in each part of the laser printer to perform a predetermined image forming operation, and is set by an operator. Various signals that specify various image forming conditions are input. Then, various signals for driving them at predetermined timing are output to various drive systems and loads provided in this laser printer, and at the same time, the paper feed roller 1
For the motor 5 that rotates the shaft 16 that fixes 4, 15,
A signal for rotating it at a predetermined rotation speed is output.

When a print start key (not shown) for starting printing is pressed, the controller 50 starts the routine shown in FIG. First, the conveyance speed of the paper feed rollers 14 and 15 is changed to that paper for a predetermined time Ts1 (see FIG. 5) at which the separation claws 41 and 42 complete the separation of the paper fed by the paper feed rollers 14 and 15. The motor 5 is rotated so that the conveyance speed V1 is lower than the paper conveyance speed V2 at the time of transferring an image.

Therefore, as shown in FIG. 6, the paper feed roller 1 is placed on the top of the sheets P stacked on the bottom plate 13.
Since the peripheral surfaces 14a and 15a of the sheet Nos. 4 and 15 come into contact with each other, the sheet feeding rollers 14 and 15 that rotate in the directions of the arrows
Thus, the paper P is fed to the right in the figure. At that time, the leading edge corners of the uppermost sheet P in the sheet feeding direction are separated by the claws 41, 42.
Since the conveyance of the sheet P is hindered by the sheet conveyance, the sheet P is bent at the corners on both sides of the portion contacting the sheet feed rollers 14 and 15 as shown in the figure, and the degree of the deflection is not less than a certain value. By the way, when the sheet buckles, it is disengaged from the separation claws 41 and 42, and the sheet is separated and fed into one sheet.

Then, in the next step shown in FIG. 7, it is judged whether or not a predetermined time Ts1 has passed, and if it has passed, the fed sheets have been separated, and this time, Increases the transport speed of the paper feed rollers 14 and 15 to the transport speed V3 (see FIG. 5) for a predetermined time Ts2. That is, in the above-described step, since the delayed portion is recovered by feeding the paper for the predetermined time Ts1 at the transport speed V1 slower than the paper transport speed V2, the paper transport speed is faster than the paper transport speed V2 for the predetermined time Ts2. The transport speed is V3.

Then, in the next step, it is judged whether or not a predetermined time Ts2 has passed, and if it has passed, the sheet is delayed and the sheet is fed at the sheet transport speed V2 from the beginning. Since the same conveyance position has been reached, in the next step, the conveyance speed of the paper feed rollers 14 and 15 is set to the predetermined time T.
The transport speed is set to V2 only for s3, and then stopped. That is, as shown in FIG. 2, the paper feed rollers 14 and 15 are rotated and stopped until the cutouts 14b and 15b reach the positions shown in the figure facing the paper surface of the paper P on the bottom plate 13.

Then, in the next step, it is judged whether or not there is the next sheet feeding, and if not, the processing of this routine is ended, but if there is, the processing returns to the first step and the above-mentioned processing and judgment are repeatedly executed. To do. Thus, in this embodiment, the conveyance speed of the paper feed rollers 14 and 15 is changed by variably controlling the rotation speed of the motor 5 (driving source) in FIG. Then, the paper feed rollers 14 and 1 that are slower than the paper transport speed (system speed) V2 when the image is transferred onto the paper.
The conveyance speed V1 of 5 is continued until at least the leading edge of the fed paper is buckled and comes off the separating claws 41 and 42, and thereafter, the conveyance speed V3 is made higher than the paper conveyance speed V2, and then the paper conveyance is performed. The paper is conveyed at the speed V2.

Therefore, the separating claws 41 and 42 are thus formed.
Even if the corner claw separating and feeding device using is used in a high-speed machine with a high conveying speed, the sheet feeding rollers 14 and 1 are used at the start of sheet feeding.
Since the sheet conveying speed V1 by 5 becomes slower than the sheet conveying speed V2, the sheet can be sufficiently buckled to be reliably separated before being fed. Therefore, the sheet separating claws 41 and 42 can be fed.
There is no possibility of damaging the part that is hanging over. After the separation of the sheets by the separating claws 41 and 42, the conveyance speed is increased to the conveyance speed V3 to recover the delayed portion, so that the high speed sheet feeding is not impaired.

The conveyance speeds of the paper feed rollers 14 and 15 are controlled by setting the conveyance speed V1 at the start of paper feeding and the paper conveyance speed V2 thereafter. Even if the position is controlled to the position shown in (4), it is possible to prevent damage to the part of the sheet that is caught by the separation claws 41 and 42. In this case, as compared with the case of the embodiment described with reference to FIG. 7, the number of image forming sheets (performance) that can be processed per unit time is slightly reduced by the amount that the conveyance speed V3 is not increased.

FIG. 8 is a schematic view showing another embodiment of the corner claw separating / feeding device according to the present invention, and the portions corresponding to those in FIG. 1 are designated by the same reference numerals. In this embodiment, the paper feed means is provided with paper feed rollers 14 'and 15' mounted eccentrically with respect to the shaft (driving shaft) 16 (similarly to the embodiment of FIG. The shaft 16 rotates at a constant speed.

Therefore, although the shaft 16 rotates at a constant speed, since the paper feed rollers 14 'and 15' are eccentrically attached to the shaft 16, the feeding speed by the paper feed rollers 14 'and 15' is increased. At least from the start of paper to the time when the fed paper buckles and comes off the separation claws 41 and 42,
The transfer speed becomes lower than the paper transfer speed (system speed) at the time of transferring an image on the paper, and thereafter, the transfer speed becomes the same as or higher than the transfer speed of the paper.

Therefore, control for changing the rotation speed of the motor for driving the paper feed rollers 14 and 15 is performed,
Just by rotating the shaft 16 at a constant speed without providing a special speed changing mechanism, the paper conveyance speed of the paper feed rollers 14 and 15 is the same as in the case of the embodiment described with reference to FIGS. 1 to 7. Until the fed paper is separated, it can be made slower than the paper carrying speed at the time of transferring an image on the paper, and then the carrying speed can be increased.

[0033]

As described above, according to the corner claw separating / feeding device of the present invention, the portion of the sheet that is caught by the separating claw is damaged from the start of sheet feeding until the sheet buckles and comes off the separating claw. Since the paper is transported at a transport speed that is slower than the paper transport speed when transferring images, the corner claw separation feeding method, which was not applicable to high-speed machines in the past, should be applied. You can Moreover, the device can be realized with a simple configuration having a small number of parts.

Further, after the separation of the sheet fed by the sheet feeding means by the separating claw is completed, the conveying speed of the sheet is made faster than the sheet conveying speed at the time of transferring an image to the sheet, and then the sheet conveying speed is set to the sheet conveying speed. Therefore , even if the conveying speed is slowed from the start of feeding to the time when the sheet buckles and comes off the separating claw, the delay can be recovered thereafter . Therefore,
It is possible to prevent a decrease in the number of image forming sheets (performance) that can be processed per unit time.

Further, if the paper feeding means has a paper feeding roller eccentrically attached to the drive shaft and the drive shaft is rotated at a constant speed, a special speed changing mechanism is provided or the drive mechanism is driven. By simply rotating the drive shaft at a constant speed without controlling the rotation speed of the shaft, the paper feed speed becomes slower than when the image is transferred to the paper until the fed paper is separated, After that, the transport speed can be increased. Therefore, it is not necessary to control the drive system for varying the rotation speed of the paper feed roller independently of the other drive systems, and the cost can be reduced accordingly.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a corner claw separating / feeding device according to the present invention together with its control system.

FIG. 2 is a schematic view showing a state in which a sheet feeding roller provided in the corner claw separation sheet feeding device also stops after feeding.

FIG. 3 is a schematic configuration diagram showing a laser printer equipped with the same corner claw separation sheet feeding device.

FIG. 4 is a perspective view showing the entire corner claw separating / feeding device of FIG.

5 is a diagram for explaining control of a sheet conveyance speed by a sheet feed roller performed by the control device 50 of FIG.

6 is a perspective view showing a state in which a sheet fed by a sheet feeding roller of the corner claw separation sheet feeding device of FIG. 4 is bent by a separation claw.

FIG. 7 is a flowchart showing a routine relating to control of a sheet conveyance speed by a sheet feed roller, which is performed by the control device 50 of FIG.

FIG. 8 is a schematic view showing another embodiment of the corner claw separating / feeding device according to the present invention.

[Explanation of symbols]

10: Corner claw separation paper feeder 14, 15: Paper feed rollers (paper feed means) 16: Shaft 41, 42: Separation claw 50: Control device P: Paper

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B65H 3/06 350 B65H 3/06 330 B65H 3/56 310 G03G 15/00 514

Claims (2)

(57) [Claims] 1. A paper feed means for coming into contact with an uppermost portion of the stacked paper sheets to feed the paper sheets, and a separation unit provided at at least one corner of a front edge of the stacked paper sheets in a paper feeding direction. In a corner pawl separating / feeding device having a pawl, the separating pawl is configured to transfer the paper fed by the paper feeding means to one.
A conveying speed changing unit is provided to make the conveying speed of the sheet by the sheet feeding unit slower than the sheet conveying speed at the time of transferring an image to the sheet until the sheet is separated.
Means for separating the paper fed by the paper feeding means.
After the separation with the release claw is completed,
After making it faster than the paper transport speed when transferring an image to paper
A corner claw separation sheet feeding device, characterized in that it has means for adjusting the sheet conveying speed . 2. The corner claw separating / feeding device according to claim 1.
In the feeding means, is decentered with respect to the drive shaft has a feed roller mounted in said drive shaft corner pawl separation sheet feeding apparatus which is characterized in that so as to uniform rotation.