JPH0776431A - Paper feeder - Google Patents

Abstract

(57) [Abstract] [Purpose] Even if it is possible to feed several different sizes of paper, it is cheap because it requires only two paper feed rollers, and there is no risk of being adversely affected by vibration during setting. A paper feeding device is provided. [Structure] A roller portion 5 of a sheet feeding roller 2 is formed in a half-moon shape, and a spiral projection 7 is formed on a large diameter portion thereof. Further, in the paper feeding device, a central separating claw 8 set to a height higher than a predetermined height level by the roller 6 is fixedly arranged on the downstream side of the paper feeding roller 2 in the paper feeding direction indicated by the arrow A. The topmost paper sheet 1-1 is bent upward by the spiral projection 7 in the approximate center in the paper width direction, and is fed beyond the central separation claw 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a means for holding the uppermost sheet of paper stacked on a bottom plate at a predetermined height level, and preventing the double feeding of the sheets to prevent the double feeding of the sheets sequentially. The present invention relates to a sheet feeding device such as a copying machine, a facsimile machine, a printer, and a printing machine, which has a sheet feeding unit.

[0002]

2. Description of the Related Art A sheet feeding device of the above type is well known, and as a double feed preventing sheet feeding means of this sheet feeding device, a device using a corner claw is widely used. In this corner claw type sheet feeding device, when the sheet feeding roller is driven to rotate, the corner claw bends the uppermost sheet of the stacked sheets, and the uppermost sheet is fed only by passing over the corner claw.

In the paper feeding device having such a structure, the distance between the corner claw and the paper feeding roller is determined by the relationship of the buckling resistance of the paper, and there are three paper feeding devices for paper of several different sizes. The above-mentioned paper feed rollers are provided. For example, in an apparatus that feeds B-series and A-series paper, FIGS.
As shown in FIG.
Many are equipped with.

[0004]

However, since the half-moon-shaped sheet feeding roller 50 has a relatively high component cost, there is a problem that the cost increases as the number of the sheet feeding rollers 50 increases. Further, in the case of a paper feed tray of an image forming apparatus or the like, when the paper feed tray is returned to the image forming apparatus or the like after paper replenishment, vibration or the like may be applied to the paper feed tray. If a paper feed device of the corner claw type is adopted for this paper feed tray, the corner claw may come off the paper due to vibrations, etc., and if one of the corner claws also comes off, good paper feeding cannot be obtained. There was also a problem. Furthermore, the corner claw type paper feeder must be temporarily retracted so that the corner claws do not get in the way when the paper is replenished and locked after the paper is replenished, and the workability is also poor.

The present invention solves the above-mentioned problems of the conventional paper feeding device, and even if it is possible to feed several kinds of paper of different sizes, only two paper feeding rollers are required, so that it is inexpensive and set. It is an object of the present invention to provide a sheet feeding device that is not likely to be adversely affected by vibration or the like at the time.

[0006]

In order to achieve the above object, the present invention provides a means for holding the uppermost sheet of sheets stacked on a bottom plate at a predetermined height level, and preventing double feeding of the sheets to prevent the uppermost sheet. In a paper feeding device having a double feed prevention paper feeding means for sequentially feeding paper, the double feed prevention paper feeding means is provided on the downstream side of the stacked papers in the paper feeding direction and in the approximate center of the paper width direction. A center protruding member whose upper end is set higher than the predetermined height level, and a paper feeding member which is arranged on both left and right sides in the paper width direction with respect to the central protruding member and has spiral protrusions formed on its peripheral surface. The twisting direction of the spiral protrusion of the sheet feeding member is a direction in which biasing forces that oppose each other with respect to the sheet are urged so that the center of the sheet in the sheet width direction is bent upward.

Further, in order to achieve the above object, according to the present invention, the sheet feeding member is a roller, and a spiral projection region is provided on a peripheral surface of the roller and a feeding action is performed on the sheet in a sheet feeding direction. A region is provided, and a notch portion is formed between the region of the spiral protrusion and the region that gives a feeding action.

Furthermore, in order to achieve the above object, the present invention is characterized in that the central projecting member is elastically displaceable.

[0009]

According to the above structure, the paper feed member causes the uppermost paper of the stacked papers to be bent upward substantially at the center in the paper width direction by the spiral protrusion, so that only the uppermost paper has the upper end higher than the predetermined height level. It is possible to separate and feed by passing over the set central protruding member. Therefore, it suffices to provide only two paper feed members on the left and right sides of the central projection member in the paper width direction.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view showing an outline of a sheet feeding device according to the present invention, and FIG. 2 is an explanatory diagram of a main part of the sheet feeding device during standby. 1 and 2, reference numeral 1 is a sheet, and 2 is a sheet feeding roller. The sheets 1 are stacked on the bottom plate 3 and are lifted by a pressing means (not shown). The paper feed roller 2 is
It comprises a roller shaft 4 rotatably driven by a driving unit (not shown) and a roller unit 5 fixed to the shaft, and the roller unit 5 is formed in a half moon shape. In this embodiment, a roller 6 rotatably mounted on the roller shaft 4 is provided as a means for holding the uppermost paper sheet 1-1 of the paper sheet 1 at a predetermined height level, and the roller 6 which is lifted by the pressing means is used. Top paper 1-
The uppermost paper sheet 1-1 is held at a predetermined height level when the roller 1 is pressed against the roller 6. As is clear from FIG. 2, the roller 6 has a larger diameter than the small diameter portion of the roller portion 5,
The diameter is set smaller than the large diameter portion, for example, 2 to 3 mm smaller.

At least the large diameter portion of the roller portion 5 of the paper feed roller 2 is made of a material having a high friction coefficient, and as is apparent from FIG. 1, the spiral protrusion 7 is formed in the large diameter portion. Further, a central separating claw 8 as a central projecting member which is set higher than a predetermined height level by the roller 6 is fixedly arranged on the downstream side of the paper feeding roller 2 in the paper feeding direction indicated by the arrow A in the paper feeding device. Two roller units 5 of the paper feed roller 2 are provided in the width direction of the paper, one on the left and right with the same distance from the central separating claw 8 in total.
The spiral projection 7 formed on the roller portion 5 has a twisting direction in which biasing forces that oppose each other with respect to the sheet 1 are biased so that substantially the center of the sheet 1 in the sheet width direction is bent upward. ing. That is, the left roller portion 5 and the right roller portion 5 of FIG.

In the sheet feeding device having the above structure, the small diameter portion of the roller portion 5 of the sheet feeding roller 2 shown in FIG.
The sheet feeding roller 2 is stopped at a position opposite to, and when a sheet feeding command is issued here, the sheet feeding roller 2 is rotationally driven in the arrow direction. When the paper feed roller 2 rotates, the spiral protrusion 7 formed on the roller portion 5 comes into pressure contact with the uppermost paper 1-1,
A feed force in the direction of arrow A and a pulling force toward the substantially central side in the sheet width direction due to the twist of the spiral protrusion 7 are applied to the uppermost sheet 1-1. At this time, the top sheet 1-1 is shown in FIG.
As shown in (a) and (b), even if the feeding force is urged, the tip is in contact with the central separation claw 8, so it stops at that position, but due to the urging force of the shifting force, the approximately center in the paper width direction is moved upward. It begins to bend. Then, as shown in FIG. 4, when the flexure of the uppermost paper sheet 1-1 exceeds the central separation claw 8, the uppermost paper sheet 1-1 of FIG.
As shown in (a) and (b), it is fed in the direction of arrow A by the biased feeding force. At this time, the second separation sheet 1-2 and thereafter are prevented from being conveyed by the central separation claw 8. After that, the uppermost paper sheet 1-1 is conveyed into the machine by a conveying roller or the like (not shown).

Thus, the paper feeding device can feed only the uppermost paper 1-1 by the cooperation of the paper feeding roller 2 and the central separating claw 8, and the paper feeding roller 2 is composed of two rollers having the spiral protrusions 7. Since it has a simple structure in which the part 5 is provided, it is inexpensive. Moreover, the sheet feeding device can feed sheets without difficulty because the distance between the two roller portions 5 and the central separation claw 8 is constant even if there are several types of sheets to be fed. Further, since the center separation claw 8 does not need to be locked to the paper like the corner claw, it does not come off due to vibration or the like like the corner claw and does not interfere with the paper supply.

By the way, the spiral projection 7 formed on the roller portion 5 exerts a feeding force in the direction of arrow A and a centering force on the uppermost sheet 1-1.
If the tip of the is beyond the central separating claw 8, the force to the center side is unnecessary, and if there is an unnecessary force, the bending becomes too large, and there is a risk that it will be caught or skewed in the next conveyance route. Can be. Therefore, it is advantageous to eliminate the pulling force and increase the feeding force in the arrow A direction when the tip of the uppermost paper sheet 1-1 passes over the central separating claw 8.

Therefore, in the paper feeding device according to the present invention, the roller portion 5 is constructed as follows. In FIGS. 6A, 6B, and 7, the large diameter portion of the roller unit 5 has a sheet feeding roller 2
In the rotation direction of, the region of the protrusion 9 parallel to the roller shaft 4 is formed following the region of the spiral protrusion 7, and the notch 10 is provided between the regions of the spiral protrusion 7 and the protrusion 9. In this case, the area of the spiral protrusion 7 is set to a peripheral length that gives a pulling force capable of surpassing the central separation claw 8 so that the amount of bending formed on the sheet 1 is large, and the notch 10 and the protrusion are formed in the remaining large diameter portion. 9 is provided.

According to this structure, when the tip of the uppermost sheet 1-1 crosses the central separating claw 8 by the spiral protrusion 7, the protrusion 9 contacts the uppermost sheet 1-1 and urges the feed force in the direction of arrow A. , The top paper 1-1 is quickly conveyed. At this time, since the notch 10 is provided between the spiral protrusion 7 and the protrusion 9, when the tip of the uppermost paper 1-1 passes over the central separation claw 8, the notch 10 faces the uppermost paper 1-1, The topmost paper sheet 1-1 is temporarily released from the paper feed roller 2 so that the flexure formed by the spiral protrusions 7 disappears. Therefore, the top paper 1-1
Is fed to the next conveying section without being bent, so that good feeding and conveying can be obtained without the risk of being caught or skewed in the next conveying section.

By the way, when a relatively thin paper is used as the paper 1 to be fed, since the central separation claw 8 is made of a material having rigidity, even if the thin paper tries to overcome this, the central portion of the paper is unnecessarily exceeded. It may be bent, and the original state may not be restored by the restoring force of the sheet 1. Since the paper that has not returned to the original state has a fold left in the center, there is a risk that the quality will deteriorate when an image or the like is transferred to the paper.

Therefore, in the present invention, as shown in FIG. 8, the central separating claw 8 is configured to be elastically displaceable. In this example, the central separating claw 8 is made of an elastic material such as elastic plastic or film. It consists of.

In the sheet feeding device having the above structure, when the uppermost sheet 1-1 sent out by the sheet feeding roller 2 hits the central separating claw 8, as shown in FIGS. 9 (a) and 9 (b), the central separating claw is formed. 8 bends and can overcome this. Therefore, the central portion of the paper can be fed separately without being bent excessively. In addition, after the paper has passed over the bent center separation claw 8,
It returns to its original state due to elastic force.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and various modifications can be made. For example, in the above-described embodiment, the roller 6 mounted between the roller portions 5 is used as the means for holding the roller 6 at a predetermined height level, but the rollers 6 may be provided on both sides of the roller portion 5. Further, the means for holding at a predetermined height level can be provided on a side fence such as a tray instead of the roller 6 of the paper.

Further, in order to elastically displace the central separating claw 8, the central separating claw 8 may be provided via an elastic body.

[0022]

According to the first aspect of the invention, only the uppermost sheet can be fed by the cooperation of the sheet feeding roller and the central separation claw, and it is inexpensive because only two expensive roller portions are required. Moreover, even if there are several paper sizes,
Since the distance between the two roller parts and the central separating claw is constant, paper can be fed without any trouble. Furthermore, since the center separation claw does not hang on the paper, it does not come off due to vibration like a corner claw,
It does not interfere with paper supply.

According to the second aspect of the invention, since the uppermost sheet can be fed without the bending of the uppermost sheet due to the notch, it is possible to obtain good sheet feeding and conveyance without fear of being caught or skewed.

According to the third aspect of the invention, since the central separation claw is elastically displaceable, the paper can be fed without bending the central portion of the paper more than necessary.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing a paper feeding device according to the present invention.

FIG. 2 is a side sectional view showing a main part of the paper feeding device in a standby state.

3 (a) and 3 (b) are a side sectional view and a front view showing the main part immediately after the start of sheet feeding.

FIG. 4 is a perspective view showing the outline after the start of paper feeding.

5 (a) and 5 (b) are a side sectional view and a front view showing the main part after the start of sheet feeding.

6 (a) and 6 (b) are a side view and a bottom view of a roller portion showing another embodiment of the present invention.

FIG. 7 is a bottom view of a paper feed roller including the roller unit.

FIG. 8 is a side sectional view showing still another embodiment of the present invention.

FIG. 9 is a side sectional view showing a state after the start of feeding.

FIG. 10 is a front view schematically showing a conventional paper feeding device.

FIG. 11 is a side sectional view of the sheet feeding device.

[Explanation of symbols]

 1 Paper 1-1 Topmost Paper 2 Paper Feed Roller 3 Bottom Plate 5 Roller Part 6 Roller 7 Spiral Protrusion 8 Center Separation Claw 9 Protrusion 10 Notch

Claims (3)

[Claims] 1. A means for holding the uppermost paper of the sheets stacked on the bottom plate at a predetermined height level, and a double feed preventing paper feeding means for preventing the double feeding of the paper and sequentially feeding the paper from the uppermost paper. In the paper feeding device, the double feed prevention paper feeding means is provided on the downstream side of the stacked papers in the paper feeding direction, and substantially at the center in the paper width direction,
A center projecting member whose upper end is set higher than the predetermined height level; and a sheet feeding member disposed on both left and right sides in the paper width direction with respect to the center projecting member, and having spiral protrusions formed on its peripheral surface, A sheet feeding device, characterized in that a spiral direction of a spiral protrusion of a sheet feeding member is a direction in which biasing forces that oppose each other with respect to a sheet are biased so that a substantially center of a sheet in a sheet width direction is bent upward. 2. The sheet feeding device according to claim 1, wherein the sheet feeding member is a roller, and a spiral protrusion region is provided on a peripheral surface of the roller, and a feeding action in a sheet feeding direction is given to the sheet. A sheet feeding device, wherein a region is provided, and a cutout portion is formed between the region of the spiral protrusion and the region to which the feeding action is applied. 3. The paper feeding device according to claim 1, wherein the central projecting member is elastically displaceable.