JP2011042079A - Paper feeder and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent, in a paper feeder for feeding a continuous printing paper having feed holes at an end portion thereof, the disadvantage that the paper feed holes slip off tractor pins, without imposing load on the continuous paper. <P>SOLUTION: A paper feed mechanism feeds the continuous printing paper having the feed holes at the end portion thereof by allowing the pins 11 engaged into the feed holes to rotate in a direction to feed the continuous paper (paper conveyance direction B) by a spline shaft 2. A shaft holder 4 for holding the spline shaft 2 is movable in a vertical direction with respect to the paper conveyance direction B. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a paper feeding device and an image forming apparatus, and more particularly to a continuous paper feeding mechanism in an electrophotographic image forming apparatus such as a laser printer.

  In an image forming apparatus using electrophotographic continuous paper, a tractor pin for conveyance is fitted into a feed hole provided at an end of the paper and is fed to a predetermined position. On the other hand, when the uniformly charged photosensitive member is irradiated with laser light, an electrostatic latent image is formed on the surface of the photosensitive member, and toner is adsorbed to the photosensitive member. The toner on the photoconductor is transferred to the surface of the continuous paper by the transfer unit. At this time, the continuous paper is in close contact with the photoconductor and is attracted to the photoconductor by an electrostatic force. It becomes easy to come off from the pin.

  For this reason, as described in Patent Document 1 and Patent Document 3, as described in Patent Document 2 or a method of reducing the attracting force on the photosensitive member side by applying a load to continuous paper. A method of attaching a pressing member for pressing the continuous paper to the tractor portion is employed. In addition, as described in Patent Document 4, a configuration in which the entire tractor portion is tilted, or as described in Patent Document 5, a method of indirectly detecting the floating of the continuous paper is employed.

  In an electrophotographic continuous paper printing device, the continuous paper is attracted to the photoconductor, so that the continuous paper feed hole is easily detached from the pin of the tractor, and the feed hole is deformed (hole galling) even if it does not come off the pin. May occur. In view of this, a suction device is provided as in Patent Document 1 to apply a load to the continuous paper, or a mechanism to apply a load in the direction opposite to the transport direction of the continuous paper as in Patent Document 3 so that the continuous paper is I try not to come off the pin. Further, as in Patent Document 2, the continuous paper is pressed against the tractor side so that the continuous paper does not come off the pin of the tractor.

  As described above, there are methods for pressing continuous paper against the tractor and means for giving continuous paper a load that surpasses the attractive force with the photoreceptor, but there is a risk that it may directly damage the continuous paper. May increase the deformation of the feed hole. Further, as disclosed in Patent Document 4, there is a configuration in which the tractor unit and the entire transfer unit are tilted to change the posture of the sheet, but this is intended to separate the transfer roller from the sheet in the transfer unit. However, this does not prevent the sheet from being detached from the pin of the tractor.

  Further, a method for detecting the floating state of the continuous paper is proposed as in Patent Document 5, but the floating state of the paper is detected by detecting the position of the flap placed on the continuous paper. However, in this case, there is a possibility that the continuous paper is moving even if the flap does not move, or a possibility that the flap is moved even if the continuous paper is not moved.

  The present invention has been made in view of the above circumstances, and in a paper feeding device that feeds paper for continuous printing having a feed hole at an end portion, the paper feed hole is formed from the pin of the tractor without imposing a burden on the continuous paper. The purpose is to prevent problems that come off.

  In order to achieve the above object, as a first aspect of the present invention, a sheet for continuous printing having a feed hole at an end is rotated in a direction in which a pin fitted into the feed hole feeds the continuous sheet by a drive shaft. Thus, a paper feeding device is provided, wherein a holder for holding the drive shaft is structured to be movable in a direction perpendicular to the paper conveyance direction.

  In order to achieve the above object, the present invention provides, as a second aspect, an image forming apparatus comprising the paper feeding device according to the first aspect.

  According to the present invention, in a paper feeding device that feeds paper for continuous printing having a feed hole at the end, it is possible to prevent a problem that the paper feed hole is detached from the pin of the tractor without imposing a burden on the continuous paper. It becomes.

It is a block diagram which shows the paper feed mechanism of the 1st form for implementing this invention. It is the block diagram which looked at the principal part of FIG. 1 from the upper part. FIG. 2 is a diagram illustrating an example of a positional relationship between a paper feed mechanism unit and a photosensitive member in FIG. 1 and an operation during printing. It is a figure which shows the structure around the tractor 1 of FIG. FIG. 2 is a diagram illustrating a state in which a continuous sheet 15 is adsorbed to a photoconductor 14 in the paper feeding mechanism of FIG. 1. It is a block diagram which shows the paper feed mechanism of the 2nd form for implementing this invention. It is a figure which shows an example of a structure of the paper feed mechanism part of FIG. 6, and a movement operation | movement.

(First embodiment)
FIG. 1 shows an embodiment of a paper feed mechanism having a mechanism in which the entire paper feed mechanism section is inclined at an arbitrary angle.

  The spline shaft 2 and the tractor shaft 3 attached to the tractor 1 are attached to the transport frame 6 by a shaft holder 4 having a built-in bearing and a fixing tractor shaft holder 5, respectively. The shaft holder 4 is always pressed downward by a spring 7 attached to the transport frame 6. On the other hand, a cam 8 is arranged at the lower part of the shaft holder 4, and the lower part of the shaft holder 4 is always in contact with the cam 8. When the cam 8 rotates, the shaft holder 4 is pushed upward. However, since the tractor 1 is configured to be rotatable around the tractor shaft 3, the tractor 1 is inclined.

  FIG. 2 shows a configuration of the paper feeding mechanism of this embodiment as viewed from above.

  As shown in FIG. 2, the tractor 1 is provided in the paper width direction, and the pulley 9 attached to the spline shaft 2 is driven by the timing belt 10, thereby driving the pin 11 of the tractor 1. The left and right tractors 1 provided in the sheet width direction can slide on the spline shaft 2 and the tractor shaft 3 in accordance with the sheet width to be used, and can be fixed at a predetermined position by the latch 12.

  FIG. 3 shows an example of the positional relationship between the paper feed mechanism and the photosensitive member, and an operation during printing.

  The transport frame 6 has a structure that opens in the direction A away from the photoreceptor 14 around the rotation shaft 13, and has a structure in which the continuous paper 15 is set on the tractor 1 with the transport frame 6 open when the paper is switched. Yes. When printing, the laser beam 17 strikes the photoreceptor 14 uniformly charged by the charger 16, thereby forming an electrostatic latent image on the surface of the photoreceptor 14, and the toner 19 is attracted to the photoreceptor 14 by the developing machine 18. To do. The continuous paper 15 is guided by the tractor cover 20 and is conveyed in the B direction in a state where the feed hole of the continuous paper 15 is fitted to the pin 11 of the tractor 1. The continuous paper 15 is pressed against the photosensitive member 14 by the retractor 21, and the toner 19 developed on the photosensitive member 14 is transferred to the continuous paper 15 by the transfer device 22.

  Normally, as shown in FIG. 4, the continuous paper 15 conveyed by the pin 11 of the tractor 1 is in a state of being guided by the tractor cover 20 and the paper guide 24 so that the feed hole does not come off from the pin 11.

  As described above, the paper feeding mechanism has a structure in which the tractor 1 can rotate around one of the two shafts that support the tractor 1, and the holder that holds the other shaft serves as the continuous paper 15. By adopting a structure that can move in a direction orthogonal to the transport direction (substantially perpendicular to the paper surface), the paper feed mechanism can be tilted. Therefore, in the present embodiment, it is possible to prevent a problem that the paper feed hole is detached from the pin 11 of the tractor 1 without imposing a burden on the continuous paper 15.

(Second Embodiment)
FIG. 5 shows a state in which the continuous paper 15 is attracted to the photosensitive member 14. The continuous paper 15 pressed against the photoconductor 14 side on the transfer device 22 by the retractor 21 normally travels on the paper guide 24 at the position of the two-dot chain line. However, when the amount of toner 19 formed on the photoconductor 14 is small, the continuous paper 15 is easily attracted to the photoconductor 14 by an electrostatic force. For this reason, the continuous paper 15 is attracted to the photoreceptor 14 rotating in the P direction and is lifted from the paper guide 24. As a result, the continuous paper 15 is guided by the tractor cover 20, but depending on circumstances. In some cases, the feed hole of the continuous paper 15 may come off the pin 11.

  Therefore, when the sensor 23 for detecting the state of the continuous paper 15 is attached to the paper guide 24 of the tractor 1 and the feed hole of the continuous paper 15 moves in the direction away from the pin 11, as shown in FIG. Thus, the movement of the continuous paper 15 is detected, and when the cam 8 rotates, the tractor 1 moves in a direction approaching the continuous paper 15, thereby preventing the feed hole of the continuous paper 15 from coming off the pin 11. ing.

  FIG. 7 shows an example of the configuration of the paper feed mechanism unit and the movement operation.

  The spline shaft 2 that rotates the pin 11 of the tractor 1 is held by shaft holders 4 a and 4 b with built-in bearings attached to the conveyance frame 6. The shaft holders 4a and 4b are provided with grooves that fit into the transport frame 6, and are configured to be movable in the vertical direction of the paper surface of FIG. The shaft holders 4a and 4b are always pressed downward by a spring 7 attached to the transport frame 6, and the lower portions of the shaft holders 4a and 4b are in contact with the cams 8a and 8b. The cams 8a and 8b are attached to the camshafts 25a and 25b, and both ends of the camshafts 25a and 25b are fixed to the transport frame 6 by a camshaft holder A26 and a camshaft holder B32 incorporating a bearing. For this reason, the camshaft holders 25a and 25b can be independently rotated.

  Gears 27a and 27b are attached to the camshafts 25a and 25b and mesh with the motor gears 29a and 29b of the motors 28a and 28b. When the motors 28a and 28b rotate, the camshafts 25a and 25b rotate. The cams 8a and 8b attached to both ends rotate. Encoders 30a and 30b are attached to the camshafts 25a and 25b, respectively, and the rotational positions of the camshafts 25a and 25b are detected by the encoder sensors 31a and 31b.

  The positions of the left and right cams 8a and 8b are adjusted so that the distances L1 and L2 from the base of the pin 11 to the photosensitive member 14 are the same within an arbitrary tolerance so that there is no difference in the height direction between the left and right tractors 1. The height of the shaft holders 4a and 4b is adjusted.

  Immediately before printing starts, the encoder sensors 31a and 31b detect the states of the encoders 30a and 30b, and the cams 25a and 25b rotate so that the left and right cams 8a and 8b are at the reference position by the action of the motors 28a and 28b. For this reason, the height of the shaft holders 4a, 4b is always kept constant immediately before the start of printing.

  When the continuous paper 15 is attracted to the photosensitive member 14 by printing and moves away from the paper guides 24a and 24b, and the feed hole of the continuous paper 15 is released from the pin 11 as shown in FIG. The sensors 23a and 23b attached to 24b detect that the continuous paper 15 has moved in the direction away from the pin 11. Then, the motors 28a and 28b are operated, and the cams 8a and 8b are rotated to move the shaft holders 4a and 4b in a direction approaching the photosensitive member 14, whereby the feed holes of the continuous paper 15 are formed as shown in FIG. The continuous paper 15 is always conveyed in a state in which the pin 11 of the tractor 1 is normally fitted normally. When the continuous paper 15 moves away from the paper guide 24a only, the movement of the continuous paper 15 is detected by the sensor 23a, and the cam 8a rotates by operating only the motor 28a, and only the holder 4a is photosensitive. Move in a direction approaching the body 14.

  The shaft holders 4a and 4b are operated by the movement of the continuous paper 15 at the time of printing. However, if the print density is known to be extremely low from the print data, the positions of the shaft holders 4a and 4b are set in advance on the photoconductor 14. It is also possible to make the state close to. Specifically, for example, the position of one or both of the shaft holders 4 according to the printing density in a certain region in the paper conveyance direction and divided into two in the width direction (left-right direction) with respect to the paper conveyance direction Adjust. On the other hand, when the printing density is high and the electrostatic attraction force with respect to the photoconductor 14 is very weak, the continuous paper 15 is retracted in FIG. 3 when the position of the shaft holders 4a and 4b approaches the photoconductor 14 more than necessary. 21 is lifted from 21 and the contact area with the photosensitive member 14 is increased, so that the print quality may be deteriorated. Further, even when thick paper is used, if the shaft holder 4 moves too far in the direction approaching the photoreceptor 14, the continuous paper 15 is wound around the paper guide 24, which may increase the load. is there. Thus, as shown in FIG. 5, when the continuous paper 15 does not move in the direction away from the pin 11, the shaft holder 4 moves in the direction returning to the reference position (the direction in which the tractor 1 moves away from the photosensitive member 14). In this process, when the sensor 23 detects that the continuous paper 15 is moving in the direction away from the pin 11, the shaft holder 4 is moved in the direction approaching the photoconductor 14. Thus, by moving the tractor 1 closer to or away from the photoconductor 14 depending on the state of the paper, the print density, and the thickness of the paper, it is possible to ensure stable paper conveyance and print quality. Become.

  As described above, the paper feeding mechanism of the present embodiment can move the movable holder within an arbitrary range by using a mechanism such as a cam. Further, the paper feed mechanism of this embodiment can tilt the paper feed mechanism unit by moving the holder in advance when the print density is extremely low due to the data to be printed.

  Further, the paper feed mechanism of the present embodiment can finely adjust the movement amount of the holder by grasping the fitting state of the paper feed pin and the continuous paper feed hole by a sensor attached to the paper feed mechanism section. Can do. That is, by changing the posture of the tractor in contact with the continuous paper and detecting the movement of the continuous paper directly with the sensor, it is possible to accurately grasp the floating state of the continuous paper.

  Further, the paper feeding mechanism of the present embodiment can move the left and right holders by the same amount of movement in the same direction by matching the drive timings of the left and right motors that move the holders. Further, the paper feeding mechanism of the present embodiment can move the left and right holders separately by independently driving left and right motors that move the holders.

  In the image forming apparatus including the paper feeding mechanism according to the first or second embodiment, the same effect as that obtained by the configuration of each of the above embodiments can be obtained.

DESCRIPTION OF SYMBOLS 1 Tractor 2 Spline shaft 3 Tractor shaft 4 Shaft holder 5 Tractor shaft holder 6 Conveying frame 7 Spring 8 Cam 9 Pulley 10 Timing belt 11 Pin 12 Latch 13 Rotating shaft 14 Photoconductor 15 Continuous paper 16 Charger 17 Laser light 18 Developer 19 Toner 20 Tractor cover 21 Retractor 22 Transfer device 23 Sensor 24 Paper guide 25 Camshaft 26 Camshaft holder A
27 Gear 28 Motor 29 Motor Gear 30 Encoder 31 Encoder Sensor 32 Camshaft Holder B
L1, L2 Distance from the base of the pin 11 to the photoreceptor 14

Japanese Patent Laid-Open No. 2007-022760 JP 2001-088996 A JP 07-215551 A JP 2003-076153 A JP-A-2005-015132

Claims (5)

A paper feeding device for feeding a paper for continuous printing having a feed hole at an end thereof by rotating a pin fitted into the feed hole in a direction of feeding the continuous paper by a drive shaft,
A paper feeding device characterized in that a holder for holding the drive shaft is movable in a direction perpendicular to the paper conveyance direction.   The paper feeding device according to claim 1, wherein the holder includes a left holder and a right holder at the left end and the right end of the drive shaft, respectively, and the left and right holders can move independently from each other on the left and right. .   The paper feeding device according to claim 1 or 2, wherein the moving amount and moving direction of the left and right holders are finely adjusted based on image data of an image to be formed on the continuous paper.   A sensor for detecting a movement of the feed hole of the continuous paper from the pin is provided, and a movement amount and a movement direction of the left and right holders are finely adjusted based on a detection result of the sensor. Item 4. The paper feeding device according to any one of Items 1 to 3.   An image forming apparatus comprising the paper feeding device according to claim 1.

Images