JP2007331905A - Paper feeder, its control method, and printer using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an improved air-picking type paper feeder capable of handling various paper sheets by enhancing separation performance of the paper sheet without damaging the advantages of the air-picking type paper feeder. <P>SOLUTION: A double feeding prevention means made of a friction member for separating double-fed paper sheets and an elastic body for pushing the double feeding prevention means against the paper sheet are installed on paper feeding passages on both sides of a suction belt. The double feeding prevention means vertically moves to the suction belt and a sucked paper sheet, and can be evacuated and fixed to an optional position. While printing is stopped, the suction belt is reversely rotated to prevent the paper sheet from remaining in the double feed prevention means portion. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a paper feeding device used in a printing apparatus such as an electrophotographic apparatus, and more particularly to a paper feeding device using an air flow suitable for high-speed printing, a control method thereof, and a printing apparatus using the same. .

  FIG. 1 shows an air pick type paper feeding apparatus using air flow and negative pressure in a conventional electrophotographic apparatus. In FIG. 1, the upper surface of the paper 2 stacked on the paper storage table 1 that can be raised and lowered is always relative to the reference surface by the control means 4 that controls the drive of the paper storage table 1 based on information from the paper upper surface detection sensor 3. It is controlled to be located at a certain height. Above the sheet 2, a suction belt 6 having a plurality of holes communicating with the suction chamber 5 and a driving device 7 for driving the suction belt 6 are installed. In addition, an air nozzle 8 is provided in front of the sheet conveyance direction to blow air to the end of the stacked sheet and lift it up. The uppermost sheet 2 floating by the air nozzle 8 is sucked by the suction belt 6. Transport and feed paper. A transport roller 21 that receives the transported paper 2 and transports it to an image forming unit (not shown) is provided downstream in the paper transport direction. A part of the sheet conveyance path is formed by the lower surface of the suction belt 8 and the conveyance roller 21. In such a sheet feeding device, various devices have been conventionally used in order to reliably prevent double feeding with a sufficient sheet separating effect by air blowing.

  For example, as shown in FIG. 2, the air nozzle 8 is positioned at the substantially central portion of the suction belt and is adsorbed by the first jet port 9 for ejecting air disposed at both ends with the substantially central portion of the suction belt 6 in between. Divided into a second jet 10 for jetting air toward the belt 6, the paper is mainly levitated at the first jet 9, and air is sent between the suction belt 6 and the uppermost paper at the second jet 10. A configuration is disclosed in which a sufficient double feed prevention effect is obtained by separating the uppermost sheet and the next sheet (see, for example, Patent Document 1 and Patent Document 2).

Patent No. 2934442 Japanese Laid-Open Patent Publication No. 2005-1855

  In recent years, due to the diversification of printed materials and the increase in printing speed and the accompanying increase in the amount of printing, higher performance has been demanded for paper feeding devices using airflow.

  One of the advantages of the air pick type paper feeder is that the paper is separated, adsorbed, and transported by the air flow. Compared to the roll pick method in which the friction material is brought into contact with the paper and separated, the friction material, the adsorption belt, etc. It is possible to obtain high reliability without worrying about wear. However, depending on the type of paper and the state of the paper, there are cases where a sufficient multi-feed preventing effect cannot be obtained even if a device such as the function of the air jet is divided.

  In view of the above situation, the object of the present invention is to add a multifeed prevention means for improving the separation performance to the conventional configuration, and enhance the sheet separation effect while retaining the high reliability that is an advantage of the air pick type sheet feeding device. It is another object of the present invention to provide a paper feeding device that can handle various types of paper.

  To achieve the above object, the invention according to claim 1 is provided with a sheet storage table for stacking and storing a plurality of sheets, a suction belt for sucking and transporting the stacked sheets one by one, and an upper portion of the sheet storage table. In a paper feeding apparatus having a first jet nozzle for use and an air nozzle having a second jet nozzle for separating suction paper, double feed prevention is provided at a position on the paper transport path that contacts the paper sucked by the suction belt. Means is provided.

  The invention according to claim 2 is characterized in that a friction member is used as the double feed preventing means.

  The invention according to claim 3 is characterized in that the double feed preventing means is provided with an elastic member for urging the friction member to the paper adsorbed on the adsorption belt.

  The invention according to claim 4 is characterized in that the double feed preventing means is provided on both sides of the suction belt on the paper conveyance path.

  The invention according to claim 5 is characterized in that the double feed preventing means is provided so as to be able to contact and retract with respect to the suction sheet.

  A sixth aspect of the invention is characterized by a printing apparatus including the paper feeding device according to the first to fifth aspects.

  A seventh aspect of the present invention is the paper feeding device according to the first, second, third, fourth or fifth aspect, wherein the suction belt is rotated in a direction opposite to a paper transport direction during a printing operation when printing is stopped. .

  In the sheet feeding device configured as described above, when the air flow from the first jet port of the air nozzle enters between the sheets and scoops the sheet, the uppermost sheet is adsorbed by the adsorption belt. The air flow ejected from the ejection port separates the uppermost sheet from the next sheet. Next, the multi-feed paper conveyed without being separated by the air flow from the second jet nozzle is separated by the multi-feed prevention means installed on both sides of the air nozzle and on the paper conveyance path with the suction belt interposed therebetween. The At this time, since the double feed preventing means is installed at a position where it does not contact the suction belt, the suction belt is not worn.

  Furthermore, when handling paper of a type that can obtain a sufficient separation effect only by the air flow from the air nozzle described above, the multifeed prevention means is retracted to a position not in contact with the paper, and the life of the double feed prevention means is extended. It is also possible to improve the reliability.

  Furthermore, when printing is stopped, the suction belt rotates in the direction opposite to the direction in which the paper is transported, and when printing is completed with the paper remaining between the suction belt and the double feed prevention means, the paper is oriented in the direction of the paper storage table. Therefore, no trouble occurs at the start of the next printing.

  Double feed prevention means comprising friction pads that come into contact with the paper and elastic members that press the double feed prevention means against the paper are installed on both sides of the suction belt and on the paper transport path of the paper. The prevention means and the elastic member are configured to be movable and retractable up and down with respect to the transport direction of the paper, and are configured to be fixed at an arbitrary position. Further, when the printing is stopped, the suction belt is rotated in the direction opposite to the paper conveyance direction during the printing operation, and the adverse effect of the paper remaining due to the attachment of the friction pad is prevented.

  Embodiments of the present invention will be described below with reference to the drawings. FIGS. 3 and 4 are diagrams showing the positional relationship of each part, and FIGS. 5 and 6 show a state in which the sheet is rolled up and floated by the air flow ejected from the air nozzle.

  In these figures, 2 is a sheet, 6 is an adsorption belt, 8 is a first ejection port 9 that ejects air toward the upper layer of the sheet, and a second ejection port 10 that ejects air toward the adsorption belt 6. The air nozzle 8 is supplied with air through a duct 19 from a blower (not shown). The suction belt 6 is stretched between two rollers so as to rotate in contact with the opening of the suction chamber 5 through which air is sucked through the duct 20, and a hole formed in the surface of the suction belt 6 is formed. The sheet 2 is sucked through.

  An operation of feeding the paper 2 in the paper feeding device will be described with reference to schematic diagrams 7 to 10. First, as shown in FIG. 7, both ends of the sheet 2 float while being separated by the air ejected from the first ejection port 9. On the other hand, the central portion of the paper has a shape that is pushed downward by the air from the second ejection port 10, and the pocket 14 is formed in the central portion of the suction belt. In this state, when the hole of the suction belt 6 is located at the opening of the suction chamber 5 and the suction starts, the uppermost sheet, that is, the first sheet 11 starts to rise as shown in FIG. The sheets after the first sheet 11 that does not exist also start to rise. In the process in which the first sheet 11 approaches the suction belt 6, as shown in FIG. 9, the air from the second ejection port 10 enters between the first sheet 11 and the second sheet 12, The first sheet 11 and the second sheet 12 are separated.

  Thereafter, as shown in FIG. 10, the first sheet 11 arriving at the suction belt 6 is conveyed by the rotation of the suction belt 6. At this time, since the leading edge of the second sheet 12 and subsequent sheets is pressed downward by the air from the second ejection port 10, the sheet weight that is dragged out by the first sheet and is transported together. No sending occurs.

  However, in the case of the state of the paper, for example, when the paper has a deformation such as curling or wavy due to moisture absorption, or when the paper has a rough cut surface, the air flow from the air nozzle 8 described above in the step shown in FIG. In some cases, separation is not sufficient and double feeding may occur. Also, when the paper surface is subjected to any treatment, such as coated paper, crimped postcard paper, or non-carbon paper, the paper is not flexible enough to be separated by airflow alone. Is likely to occur.

  Therefore, in the embodiment of the present invention, as shown in FIGS. 3 and 4, double feed preventing means comprising friction pads 13 at positions on the paper conveyance path on both ends with the suction belt 6 in contact with the front edge in the paper conveyance direction. A spring 15 for pushing up the friction pad 13 in the direction of the suction belt and the suction paper is attached, and a resistance is received from the friction pad 13 when the paper 2 is conveyed by the suction belt 6. By appropriately setting the friction coefficient of the friction pad 13 and the pressing force by the spring 15, the double fed sheets are separated as shown in FIG. 11. If the friction pad 13 is installed in this way, it does not come into contact with the suction belt 6, so there is no concern about the wear of the suction belt. A portion of the friction pad 13 facing the front end of the sheet is provided with an inclined surface to realize smooth sheet pickup. The friction pad 13 may be made of metal, plastic, cork, or other material that provides optimum resistance for multi-feed separation according to the friction resistance of the paper. Further, if the friction pad itself is formed of an elastic material such as sponge, the elastic body can be integrated with the pad.

  Further, the friction pad 13 and the spring 14 are held by a holder 16, and the holder 16 is fitted in a groove portion 17 formed in the air nozzle 8 to move up and down and can be fixed by a screw 18 at an arbitrary position. As a result, the friction pad 13 is retracted to a position where it does not come into contact with the paper 2 for the type of paper for which a sufficient double feed prevention effect can be expected only by the air flow from the air nozzle 8, and the friction pad 13 and the suction belt 6 are retracted. It is possible to improve the reliability of the apparatus by extending the service life of the parts.

  Further, when the printing is finished while the paper whose double feeding is prevented is sandwiched between the friction pad 13 and the suction belt 6, or printing is stopped due to a paper jam or the like, the paper is stopped by the friction pad 13 and the suction belt 6. 12 or the like, as shown in FIG. 12, the suction belt 6 is reversed when the printing is stopped, and the paper is returned to the paper storage table. Therefore, no trouble occurs at the start of the next printing.

  As described above, according to the embodiments of the present invention, it is possible to provide a paper feeding device that can handle a wider variety of papers without increasing the width of paper that can be handled and the high reliability that is an advantage of the air pick type paper feeding device. .

  In this embodiment, a good separation performance was obtained by setting the friction coefficient of the friction pad 13 to the sheet to about 1.3 and the pressing force by the spring 15 to about 50 (gf). The friction coefficient 13 and the pressing force by the spring 15 are appropriately determined according to the relationship between the conveying force of the suction belt 6, the air jet pressure from the air nozzle 8, the acceleration of the paper, and the like.

It is a perspective view which shows the paper feeder using the conventional air flow. It is a front view which shows the paper feeder using the conventional airflow. It is a front view which shows the Example of this invention. It is a side view which shows the Example of this invention. It is a front view which shows the Example of this invention. It is a longitudinal cross-sectional view which shows the Example of this invention. FIG. 2 is a schematic diagram illustrating the principle of a sheet feeding device according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating the principle of a sheet feeding device according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating the principle of a sheet feeding device according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating the principle of a sheet feeding device according to an embodiment of the present invention. It is a side view which shows the Example of this invention. It is a side view which shows the Example of this invention.

Explanation of symbols

1 is a sheet storage table, 2 is a sheet, 3 is a sheet upper surface detection sensor, 4 is a control means, 5 is a suction chamber, 6 is a suction belt, 7 is a driving device, 8 is an air nozzle, 9 is a first outlet, Second ejection port, 11 is the first sheet, 12 is the second sheet, 13 is the friction pad, 14 is the pocket, 15 is the spring, 16 is the holder, 17 is the groove, 18 is the screw, 19 is the duct, 20 is a duct, and 21 is a transport roller.

Claims (7)

A sheet storage table for stacking and storing a plurality of sheets, a suction belt provided at the top of the sheet storage table for sucking the stacked sheets one by one and transporting them to a sheet transport path, and an air nozzle provided at the top of the sheet storage table In a paper feeding device comprising a first jet port for spreading a plurality of stacked paper sheets and an air nozzle having a second jet port for separating the paper adsorbed to the suction belt from the next stacked paper,
A sheet feeding device, comprising: a multifeed prevention unit provided at a position on the sheet conveyance path in contact with the sheet sucked by the suction belt.   The sheet feeding device according to claim 1, wherein the double feed preventing unit includes a friction member.   3. The paper feeding device according to claim 1, wherein the double feeding prevention means is provided with an elastic member that urges the double feeding prevention means to the paper sucked by the suction belt.   4. The paper feeding device according to claim 1, wherein the double feeding preventing means is provided on both sides of the suction belt on the paper conveyance path.   5. The sheet feeding device according to claim 1, wherein the double feed preventing means is provided so as to be able to contact and retract with respect to the sheet adsorbed by the adsorption belt.   A printing apparatus comprising the paper feeding device according to claim 1, 2, 3, 4 or 5. 6. The paper feeding device control method according to claim 1, wherein when the printing is stopped, the suction belt is rotated in a direction opposite to a paper transport direction during a printing operation.

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