JP3135356B2 - 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 paper feeder, and more particularly to a paper feeder characterized by a double feed prevention mechanism suitable for a printing press.

[0002]

2. Description of the Related Art Conventionally, there have been proposed many types of paper feeders having a double feed prevention mechanism.

For example, a paper feeder in which a friction member such as a friction pad or a rubber roller is brought into pressure contact with a paper feed roller to separate double feeds at a nip portion thereof is disclosed in Japanese Patent Application Laid-Open Nos. This is well known in, for example, Japanese Patent Publication No.

[0004] Some of the devices using the friction pad have a concave shape, that is, a shape along the outer shape of the sheet feeding roller, and attempt to perform separation in a longer range. However, it is not always possible to overcome the momentum of a plurality of paper bundles that have entered at a time, and there is a case in which multiple paper feeds are performed.

[0005] The above-mentioned paper double feed prevention mechanism is logically 2nd.
The separation condition is satisfied only when two sheets enter between the paper feed roller and the friction member, and it is impossible to separate only one sheet when three or more sheets enter. .

[0006] The friction member is not simply pressed against the paper feed roller as described above, but when necessary, that is, when a plurality of sheets are fed between the paper feed roller and the friction member (in this case, the reverse roller), that is, the separation portion. There is also widely known a system in which the reverse roller is continuously reversed only when the vehicle enters the vehicle.

In this method, since the reverse roller is continuously rotated in reverse, even if a plurality of sheets enter the separation section, the lower sheets are pushed back one after another in the direction opposite to the sheet feeding direction, and the remaining sheet is moved by one. When the sheets are stacked, the reverse roller is prevented from rotating in the reverse direction by the sheet, and can be turned forward to feed only the sheet.

[0008]

However, in general, this mechanism is effective only for medium-to-low-speed paper feeding, and can return multi-fed paper to high-speed paper feeding such as a printing press. Could be double-fed.

As described above, in the conventional double feed prevention apparatus, when a plurality of sheets (three or more sheets) simultaneously enter the separation section in any of the mechanisms, it is difficult to surely separate the sheets one by one.

[0010] In the first place, a double feed means that a plurality of sheets are sent out by a sheet feed roller at a time from a state in which they are stacked on a sheet feed table, with a slight or no shift therebetween, and the sheets are completely separated by a separation unit. This is a state in which the paper cannot be separated into several pieces, and depending on the paper, more than ten sheets may be displaced.

A possible cause of the shift is that the coefficient of friction between the sheets of the sheet bundle stacked on the sheet feeding table becomes extremely small depending on the location. It is often seen at the boundary when stacking paper or adding paper to the paper feed tray.

[0012] In addition, papers that have been printed once for multicolor printing or the like are aligned and stacked on a paper feed table several times,
Even when different types of papers are mixed, the overlapping surface becomes slippery. Look for a slippery surface and move it up and down
It was known that removing the sheets one by one could prevent the sheet from shifting, but the operator was forced to do so each time.

In other words, it is not an exaggeration to say that it is inevitable to avoid this paper misalignment when using the printing press.

The present invention provides a sheet feeder which can prevent the above-mentioned misalignment of sheets causing double feed with an extremely simple and inexpensive mechanism, and can perform a sufficient separating operation with a conventional separating mechanism. It is intended to be.

[0015]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a paper feed tray on which paper is loaded, a guide member for regulating the position of the leading end of the paper loaded on the paper feed tray, and a paper stack loaded on the paper feed tray. A paper feed roller that rotates in a predetermined direction by an external driving force while applying a predetermined pressure to the paper in order to send out the paper, and a friction member pressed against the paper feed roller. A paper feed device that separates and feeds the paper loaded on the paper feed table one by one by a difference in friction coefficient between the paper feed roller and the paper, the friction member and the paper, and between the papers. Just below the rotation center of the paper feed roller
Upstream of the sheet feeding direction, and on both sides of the sheet feeding roller.
A pair of protrusions provided at an upper end of the guide member;
Before the paper separating operation by the friction member
The stop position of the paper is aligned by contacting the pair of protrusions.
This is achieved by means of:

[0016]

[Function] Upward in the paper feed direction from directly below the rotation center of the paper feed roller
The flow side, and a pair of projections provided at the upper end of both sides of the guide member of the sheet feeding roller is movable in a direction perpendicular to the axial direction of the paper feed roller, also, the projections paper feed roller side guides It slopes down towards the height of the corners of the plate.

If there is a slippery surface in the sheet bundle, the sheets above the sheet bundle are likely to be shifted in the sheet feeding direction. Then, only the uppermost sheet of the sheet bundle or only a few upper sheets are conveyed to the separation unit.

[0018]

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

FIG. 1 is a schematic configuration diagram of a sheet feeding device according to a first embodiment, FIG. 2 is an enlarged view of a main part thereof, and FIG. 3 is a front view of a sheet feeding roller portion.

In FIG. 1, reference numeral 1 denotes a paper feed roller, which is driven to rotate in a direction indicated by an arrow in FIG. Below, a friction pad 2 is fixed to a holder 3, and is elastically urged toward a paper feed roller 1 by a separation pressure spring 4 to form a paper separation portion. Also,
Instead of the friction pad 2, a friction member such as a rubber roller may be used. The other end of the separation pressure spring 4 is set in a part of the engagement portion 5 a of the guide plate 5. Also,
A window is provided in a part of the guide plate 5, and the holder 3 is slidably supported along a part 5b of a rib provided on the back side. The paper feed table 8 is supported so as to be rotatable around a shaft 10, and is urged clockwise by a paper feed pressure spring 9.

A pair of protrusions 6 are provided at the corners 5c of the guide plate 5.
Are provided with a predetermined gap from the outer peripheral surface of the paper feed roller 1. The protrusions 6 are located on both sides of the paper feed roller 1, and the side facing the paper feed roller 1 is inclined downward toward the height of the corner 5c (see FIG. 3). Reference numeral 5d denotes a rib provided in a band shape on the surface of the guide plate 5 at a predetermined interval to guide and hold the leading end of the paper 7.

Next, the double feed prevention operation of the sheet feeding device will be described.

When the sheet feeding operation is started, the sheet feeding roller 1 is rotated at a predetermined timing by a driving device (not shown) in a direction indicated by an arrow in FIG. Accordingly, the uppermost sheet of the sheets 7 stacked on the sheet feeding table 8 starts to be fed, passes through the separation unit, and is sent to a registration roller (not shown).
The driving of the paper feed roller 1 stops. Since the paper feed roller 1 has a one-way clutch, even if the paper is started to be fed by the registration roller, the paper feed roller 1 is pulled by the paper 7 and rotates.

Here, assuming that there is a slippery surface 11 in the stacked sheets 7 as shown in FIG. 4, the sheets 7 tend to shift in the sheet feeding direction as the sheets are fed. However, the bundle of sheets that have been gathered is
As shown in FIG. 5, the protrusion 6 provided on the portion 5c abuts on the front edge portion 6a, and is prevented from entering the separating portion temporarily, and only the uppermost sheet of the sheet bundle is conveyed to the separating portion. According be fed, heavy since starting at the time that the number of sheets bundle also has decreased gradually decreases its use paper stack but will enter the separation section, has decreased to the number that can be separated in previously conventional separation mechanism There is no need to worry about sending.

Of course, the gap between the sheet feeding roller 1 and the projection 6 is usually small enough not to hinder sheet feeding. Also,
The protrusion 6 is fixed in the embodiment, but may be movable in a direction in which the gap between the paper feed roller 1 and the paper feed roller 1 can be changed by the paper as shown in FIG. That is, a pair of long holes 17a in the vertical direction may be formed in the fixing plate 17 on which the projections 6 are formed, so that the fixing plate 17 can be moved up and down.

FIG. 7 is a schematic configuration diagram of a sheet feeding device according to the second embodiment.

Basically, it is the same as the apparatus of the first embodiment. The sheet 7 is lifted from below to press the sheet 7 against the sheet feeding roller 1 to generate the sheet feeding pressure.
In the case of this embodiment, the sheet separating section and the sheet feeding pressure acting section are divided, and the pick-up roller 12 is supported by an arm 15 so as to be swingable around the sheet feeding roller 1, and the pick-up roller is 12 parts own weight and spring 13
The force difference acts as a sheet feeding pressure on the sheet 7. The feed roller 1 and the pickup roller 12 are connected to the timing belt 1.
When the paper feed roller 1 receives a driving force from the outside, the pick-up roller 12 starts rotating at the same time.

When a predetermined number of sheets have been fed, the pick-up roller 12 rotates counterclockwise around the sheet feeding roller 1 accordingly. When this is detected by the detecting means (not shown), the sheet feeding table 8 is raised by the driving means (not shown), and when the pickup roller 12 is returned to the original position, the detecting means operates and the ascending operation is terminated.
The paper feeding operation is continued.

Although the present invention has been described with reference to specific embodiments, it is to be understood that the invention is not limited thereto.
It will be apparent to those skilled in the art that various embodiments are possible within the scope of the present invention.

[0030]

According to the first and third aspects of the present invention, paper feeding
On the upstream side in the paper feed direction from immediately below the roller rotation center, and
A pair of protrusions are provided on the upper end of the guide member on both sides of the feed roller.
Before the paper separation operation by the paper feed roller and the friction member,
The leading edge of the paper abuts on the pair of protrusions to set the paper stop position.
Because the paper is fed,
If you try to shift the paper in the paper feeding direction,
The bundle hits the protrusion and temporarily blocks entry into the separation section
Only the top sheet of the stack is transported to the separation unit.
In other words, the feed roller and friction member
Stop the paper in advance and align the paper in front of the paper separation section.
Therefore, it is possible to prevent a shift of the sheet bundle that causes double feeding in the sheet separating unit . Further, the operator does not need to search for a slippery surface and remove the upper and lower surfaces one by one, so that the operator can concentrate on the operation with ease. Furthermore, since the mechanism is very simple, it is highly reliable and can be realized at low cost.

According to the second aspect of the present invention, the gap between the projection and the paper feed roller is made variable .
The shift amount of the paper to be dealt with can be set freely.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a sheet feeding device according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the sheet feeding device according to the first embodiment of the present invention.

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

FIG. 4 is an explanatory diagram of a double feed prevention operation of the sheet feeding device according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a double feed prevention operation of the sheet feeding device according to the first embodiment of the present invention.

FIG. 6 is a front view showing a projection moving mechanism.

FIG. 7 is a schematic configuration diagram of a sheet feeding device according to a second embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 paper feed roller 2 friction pad 3 holder 4 separation pressure spring 5 guide plate 5 a engaging part 5 b part of rib 5 c corner 5 d rib 6 protrusion 6 a front edge of protrusion 7 paper 8 paper feed table 9 paper feed pressure Spring 10 Shaft 11 Paper sliding surface 12 Pick-up roller 13 Spring 14 Timing belt 15 Arm 16 Eccentric cam

Claims (3)

(57) [Claims] A sheet feeder on which sheets are stacked, a guide member for regulating the position of the leading end of the sheets stacked on the sheeter,
A sheet feeding roller that rotates in a predetermined direction by an external driving force while applying a predetermined pressure to the sheet to send out the sheet stacked on the sheet feeding table; A friction member pressed against the paper feed roller, and the paper loaded on the paper feed table is separated one by one by a difference in friction coefficient between the paper feed roller and the paper, the friction member and the paper, and between the papers. In the paper feeding device, the upstream side in the paper feeding direction from immediately below the rotation center of the paper feeding roller.
At the upper ends of the guide members on both sides of the paper feed roller.
Before the paper separation operation by the paper feed roller and the friction member , comprising a pair of protrusions
The leading edge of the sheet abuts on the pair of protrusions to stop the sheet.
A paper feeder characterized in that the paper feeders are aligned . 2. The device according to claim 1, wherein the protrusion is provided so as to be movable in a direction orthogonal to an axial direction of the paper feed roller,
A sheet feeding device characterized in that a gap between the two can be changed. 3. The method of claim 1, wherein the projection includes a sheet
Sheet feeding apparatus characterized by downstream side in the sheet direction is inclined obliquely downward.