JP2007112528A - Branching device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a branching device in which a branch claw is not rotated even if a pressure of a return spring is reduced, and an image forming device. <P>SOLUTION: The branching device is provided with the branch claw 9 provided so as to switch a conveying direction of paper to a first conveying passage 22 and a second conveying passage 23; an urging member (18) for urging the branch claw such that the first conveying passage is released and the second conveying passage is closed; an operation member for operating the branch claw in resistant to urging force of the urging means such that the first conveying passage is closed and the second conveying passage is released; and guide members 19, 21 for guiding the paper passed through the branch claw to the first conveying passage or the second conveying passage. The branch claw 9 is pivotally supported normally/reversely rotatably and the rotation fulcrum position is positioned at the same position as a portion 9b abutted with the conveyed paper or in a downstream in a conveying direction than the portion in the branch claw 9 in the first conveying passage is released and the second conveying passage is closed by receiving urging of the urging member. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a branch device used in an image forming apparatus such as a copying machine, a printer, and a facsimile, and the image forming apparatus.

  Conventionally, for example, a paper discharge method of an image forming apparatus such as a copying machine or a printer includes a face-down method of discharging paper with the image surface side facing down and a face-up method of discharging paper with the image surface facing up. Are known. Further, the image forming apparatus as described above is provided with double-sided conveying means for printing images on both sides of the paper, and the paper discharge direction after the image formation can be switched to a desired direction according to the application. A branching device has already been proposed by the present applicant (see, for example, Patent Document 1).

  The branching device in the conventional image forming apparatus disclosed in Patent Document 1 has a branching claw, a return spring that urges the branching claw so that, for example, a transporting path for discharged paper is opened, and a double-sided transporting path is opened. The branching claw is switched once at a time between the sheets. Since the solenoid rises in temperature with operation and the solenoid itself becomes large in order to produce a large suction force, the pressure of the return spring should be as small as possible. However, if the pressure of the return spring is low during normal duplex printing, when the transported paper comes into contact with the branch claw, the branch claw rotates against the force of the paper and closes the transport path for the discharged paper. There is a problem that.

Japanese Patent Laid-Open No. 10-181978

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a branching device and an image forming apparatus in which the branching claw does not rotate even if the pressure of the return spring is reduced, solving the problems of the conventional one.

  In order to solve the above-mentioned problem, the invention according to claim 1 is provided with a branching claw provided so as to be able to switch the paper transport direction between the first transporting path and the second transporting path, An urging member that urges the conveying path to open and the second conveying path to close, and the first conveying path closes and the second conveying path opens against the urging force of the urging means. A branching device comprising an actuating member that operates the branching claw and a guide member that guides the paper that has passed through the branching claw to the first transport path or the second transport path. Is supported by the branching claw in a state where the first conveyance path is opened and the second conveyance path is closed with the rotation fulcrum position being biased by the biasing member. It is characterized in that it is at the same position as the part where the sheet abuts or at a position downstream of the part in the transport direction. According to a second aspect of the present invention, in the first aspect, the actuating member is a solenoid. According to a third aspect of the present invention, in the first aspect, the actuating member is a stepping motor.

  According to a fourth aspect of the present invention, there is provided an image forming apparatus comprising the branching device according to any one of the first to third aspects. According to a fifth aspect of the present invention, in the fourth aspect, the image forming apparatus is any one of a copying machine, a printer, and a facsimile.

  The present invention is as described above, and the branching claw is pivotally supported so as to be able to rotate in the forward and reverse directions, and the rotation fulcrum position is urged by the urging member so that the first conveyance path is opened and the second conveyance is performed. Since the branching claw with the path closed is at the same position as the part where the conveyed paper abuts or at a position downstream of the conveyance direction, the branching claw does not move even if the pressure of the biasing member (return spring) is reduced. In other words, when the transported paper comes into contact with the branching claw, the branching claw rotates against the force of the paper when it is in contact with the branching claw. It is possible to solve the problem of closing the paper conveyance path.

  An embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic view of an image forming apparatus with a duplex conveying device. In the illustrated image forming apparatus, the paper 3 loaded on the paper feed tray 2 in the apparatus main body 1 is conveyed by the paper feed roller 4, the image and the paper are aligned by the resist roller pair 5, and transferred to the photoreceptor 6. An image is formed on one side of the paper by the belt 7, and then the toner image on the surface of the paper is melt-fixed on the paper by the fixing roller pair 8. Thereafter, when printing is not performed on both sides of the paper, the paper is conveyed to the paper discharge roller pair 10 by the branching claws 9 and discharged to the paper discharge tray 11. However, when printing is performed on both sides of the paper, the branching claws 9 and the second branching claws are performed. 12, the sheet conveyance path is switched, and the sheet is guided to the switchback conveyance path 15 via the conveyance roller 13 and forward / reverse rotation roller 14. When the trailing edge of the paper entering the switchback conveyance path 15 exceeds the leading end of the second branch claw 12, the forward / reverse rotation roller 14 is reversed and the second branch claw 12 is operated to guide the paper to the re-conveyance path 16. Then, printing is performed on the reverse side of the sheet through the registration roller pair 5.

  Double-sided printing is possible by using the above-described conveyance path. However, when the conveyance process is performed for each sheet, productivity of double-sided printing is extremely deteriorated. Therefore, the productivity of double-sided printing is improved by adopting a non-stack interleaf system that alternately performs the back surface printing operation from the re-transport path 16 and the front surface printing operation from the paper feed tray 2. When this interleaf system is adopted, the branching claw 9 switches the conveyance path for each sheet. However, in order to secure higher productivity, even if the paper interval between the papers is shortened, the short paper interval is reduced. A branching device that can branch the paper with high accuracy is required.

  FIG. 2 is a sectional view of the branching device. Reference numeral 17 denotes a rotating shaft of the branching claw 9, 18 denotes a return spring, 19 denotes a pair of guide plates, 20 denotes a stopper of the branching claw 9, and the stopper 20 is fixed to the upper guide plate 19. Reference numeral 21 denotes a pair of second guide plates. The branch claw 9 is always rotated in the direction of the arrow c by the tensile force b of the return spring 18, and the abutting portion 9 a abuts against the stopper 20 and is stationary. The rotation shaft 17 is provided such that its rotation fulcrum position is at the same position as the portion 9b (paper delivery section) where the paper conveyed by the branching claw 9 abuts or at the downstream of the conveyance direction. A pair of guide plates 19 forms a sheet transport path 22 for paper discharge, and a pair of second guide plates 21 forms a sheet transport path 23 for duplex printing. The conveyance path 23 is connected to the switchback conveyance path 15. As shown in the figure, the branch claw 9 opens the conveyance path 22 and closes the conveyance path 23 in a normal state where double-sided printing is not performed, and needs to close the conveyance path 22 and open the conveyance path 23 when performing double-sided printing. However, in such a case, a solenoid (not shown) is operated. This solenoid rotates the branch claw 9 with a force larger than the pulling force b of the return spring 18 to close the transport path 22 and open the transport path 23 as described above.

  Since it is as described above, the branching claw 9 is normally urged and positioned by the pulling force b of the return spring 18 as shown in FIG. 2 to open the conveying path 22 and close the conveying path 23. Therefore, the sheet discharged after fixing is conveyed as shown by arrow a and collides with the portion 9b of the branch claw 9, and the direction is changed in the direction of the conveyance path 22 by this collision, and the sheet is directly moved to the same conveyance path. Sent. At this time, when the sheet enters from the arrow a and collides with the portion 9b of the branch claw 9, if it is considered that there is no resistance between the sheet and the branch claw 9, a force F that causes the sheet to collide with the branch claw 9 as shown in FIG. Is divided into component forces F ′ and F ″, and the force applied by the paper to the branch claw 9 becomes the component force F ′, and the force for rotating the branch claw 9 does not work. The pressure of the spring 18 can be reduced, thereby reducing the size, cost and temperature of the solenoid.

  When the solenoid is operated during double-sided conveyance, the branching claw 9 rotates in the direction opposite to the arrow c against the pulling force b of the return spring 18 and is positioned as shown by the chain line in FIG. Then, the conveyance path 23 is opened. Therefore, the sheet discharged after being fixed collides with a portion of the branching claw 9 on the side opposite to the portion 9b and then is conveyed in the direction of the conveying path 23. Thereafter, when the solenoid is deactivated, the branching claw 9 is urged by the tensile force b of the return spring 18 and returns to the position indicated by the original solid line. As described above, when the rotation fulcrum position of the branching claw 9 is set to the same position as the portion 9b where the paper to be conveyed abuts on the branching claw, or the position downstream of the conveyance direction, the pressure of the return spring 18 can be reduced.

  In the above description, the solenoid is shown as the member that operates the switching of the rotation direction of the branching claw 9 against the tensile force b of the return spring 18, but a stepping motor that rotates forward and backward may be used instead of the solenoid. Even in the case of such a stepping motor, the pressure of the return spring 18 urging the branch claw 9 can be reduced. In addition, the torque of the motor can thereby be reduced, and the motor can be reduced in size, cost can be reduced, and temperature rise can be reduced.

  Note that the shape and structure of the branching claw 9 shown in the embodiment is merely a preferable example, and is not limited to the shape and structure shown in the figure, and any shape and structure can be adopted. The return spring 18 may be other than the above as long as it has a function as a return spring. In the embodiment, an example in which the conveyance path of an image-formed sheet is switched has been described. Further, the switching transport path can be applied not only to switching between a transport path for discharged paper and a transport path for paper to be printed on both sides, but also to switching other transport paths. In addition, the detailed design can be arbitrarily changed and modified during implementation within the scope of the claims.

  Next, a characteristic effect of the invention described in claim 2 and the following claims will be described. According to the second aspect of the present invention, by reducing the pressure of the return spring, it is possible to reduce the size of the solenoid, reduce the cost, and lower the temperature rise.

  According to the third aspect of the present invention, the holding torque can be reduced, and the motor can be reduced in size, cost can be reduced, and temperature rise can be reduced.

  According to the fourth and fifth aspects of the present invention, an image forming apparatus equipped with a branching device can be provided.

1 is a schematic view of an image forming apparatus with a duplex conveying device according to an embodiment of the present invention. It is an enlarged view of a part with a branch nail | claw same as the above. It is an operation explanatory view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Paper feed tray 3 Paper 4 Paper feed roller 5 Registration roller pair 6 Photoconductor 7 Transfer belt 8 Fixing roller pair 9 Branch claw 10 Paper discharge roller pair 11 Paper discharge tray 12 Second branch claw 13 Transport roller 14 Forward / reverse rotation Roller 15 Switchback transport path 16 Re-transport path 17 Rotating shaft 18 Return spring (biasing member)
19, 21 Guide plate 20 Stopper 22 Transport path (first transport path) 23 Transport path (second transport path)

Claims (5)

  A branching claw provided so that the paper transport direction can be switched between the first transporting path and the second transporting path, and the branching claw is attached so that the first transporting path is opened and the second transporting path is closed. An urging member that urges, an actuating member that operates the branching claw so that the first conveyance path is closed and the second conveyance path is opened against the urging force of the urging means; A branching device comprising a guide member for guiding the passed paper to the first transporting path or the second transporting path, wherein the branching claw is pivotally supported so as to be able to rotate forward and reverse, and the rotation fulcrum position thereof is The same position as the portion where the sheet to be conveyed abuts on the branching claw in a state where the first conveyance path is opened and the second conveyance path is closed under the urging force of the urging member, or a position downstream in the conveyance direction from the portion. A branching device characterized by that.   The branching device according to claim 1, wherein the operating member is a solenoid.   The branching device according to claim 1, wherein the operating member is a stepping motor.   An image forming apparatus comprising the branching device according to claim 1.   The image forming apparatus according to claim 4, wherein the image forming apparatus is any one of a copying machine, a printer, and a facsimile.

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