JP2006225098A - Feeding device and image forming device provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely feed a paper sheet for preventing false detection of presence/absence of a paper sheet on a manual paper feeding tray even if a turn-back phenomenon of the paper sheet occurs in the feeding device, and surely feeding the paper sheet if there is a paper sheet on the manual paper feeding tray. <P>SOLUTION: When a sensor 41 detects that there is no paper sheet on the manual paper feeding tray 21 in the middle of the feeding, a paper feeding roller 25 is turned around for a predetermined time. When the sensor 41 detects that there is no paper sheet on the manual paper feeding tray 21 again, it is determined that there is no paper sheet on the manual paper feeding tray 21 to stop the paper feeding roller 25 and stop feeding the paper sheet. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sheet feeding device and an image forming apparatus using the same, and more particularly to a sheet feeding device including a so-called manual feed tray and an image forming apparatus using the sheet feeding device.

  In recent years, from the viewpoint of reducing the occupation area of an image forming apparatus in the workplace or home, a so-called in-cylinder discharge type apparatus in which the sheet conveyance direction is set to the vertical direction and the sheet discharge unit is provided at the center in the vertical direction of the apparatus has been widely used. It's getting on. The sheet feeding from the manual feed tray in the in-body discharge type apparatus is performed as follows, for example. As shown in FIG. 6, the paper P is placed on the manual feed tray 21 so that the front end portion is hung on the lifting plate 22. A sensor 41 for detecting the presence / absence of paper is disposed on the paper placement portion of the elevating plate 22. When paper feed from the manual feed tray 21 is detected by the sensor 41, it is displayed on the display unit (not shown) of the image forming apparatus that there is no paper in the manual feed tray 21, Paper feeding operation is not performed.

  When the image forming operation is started, the paper feed roller 24 rotates, and the elevating plate 22 is pushed upward by the push spring 23 in synchronization with the rotation of the paper feed roller 24. When the elevating plate 22 is pushed upward, a number of sheets are pulled out from the upper side of the elevating plate 22 in the transport direction by the rotating paper feed roller 24. Then, at the pressure contact portion between the sheet feeding roller 24 and the separation pad 25, only the uppermost one of the sheets is conveyed to the registration roller pair 80.

  Here, as shown in FIG. 7, the elevating plate 22 is moved to a position where it is separated from the paper feed roller 24 and a position where it is pressed by a cam 60 and a push spring 23 mounted on the rotation shaft 241 of the paper feed roller 24. . When the paper feed roller 24 is stopped, the protrusion 611 of the cam 60 abuts on the lift plate 22, and the lift plate 22 is located away from the paper feed roller 24. When the paper feed roller 24 rotates, the protrusion 611 of the cam 60 is disengaged from the lift plate 22, and the lift plate 22 moves in a direction in which it presses against the paper feed roller 24 by the push spring 23. And keep this state for a while. That is, as shown in FIG. 6, the paper P on the elevating plate 22 is pulled out in contact with the paper feed roller 24, and the uppermost paper is conveyed to the registration roller pair 80 at the pressure contact portion between the paper feed roller 24 and the separation roller 25. The elevating plate 22 is urged in the direction in which it is pressed against the paper feed roller 24 until the leading edge of the conveyed paper is nipped by the registration roller pair 80. Then, in synchronization with the leading edge of the conveyed paper being nipped by the registration roller pair 80, as shown in FIG. 7, the protrusion 611 of the cam 60 comes into contact with the elevating plate 22 again, and the elevating plate 22 feeds the paper. The position is separated from the roller 24. The paper feed roller 24 is temporarily stopped in this state. When the sensor 42 (shown in FIG. 6) detects that the trailing edge of the sheet nipped by the registration roller pair 80 has passed through the registration roller pair 80, the paper feed roller 24 starts rotating again and continues to the next. Feed paper. This series of operations is repeated to feed paper.

  By the way, when the above-described elevating plate 22 is moved away from the pressure contact position, the paper that is sandwiched between the paper feed roller 24 and the separation pad 25 and not conveyed to the registration roller pair 80 is repelled by its own weight and bending. A phenomenon (return phenomenon) that deviates in the direction opposite to the paper conveyance direction occurs due to a complex force such as the above. In particular, such a phenomenon frequently occurs when the last sheet on the lifting plate 22 is thick paper such as an envelope or a postcard.

If the leading edge of the paper P is positioned downstream of the detection position of the sensor 41 that detects the presence or absence of the paper due to the paper return phenomenon, the paper P is present on the manual feed tray 21. A message indicating that there is no paper in the manual feed tray 21 is displayed on the device display unit (not shown), and the paper feeding operation is not performed.
Japanese Patent Laid-Open No. 10-45269 (Claims)

  Therefore, as shown in FIG. 8, the attachment position of the sensor 41 for detecting the presence or absence of paper is set upstream of the vertical line (broken line in the figure) drawn from the central axis of the paper feed roller 24 in the paper transport direction. The sensor 41 can detect the presence of paper even if a return phenomenon occurs.

  However, by setting the sensor 41 to such an attachment position, it is possible to prevent erroneous detection of the presence or absence of paper, but when the paper P is placed on the manual feed tray 21, the front end of the paper is directed to the direction of the lifting plate 22. Since the sensor 41 detects the presence of the paper P even if the paper P is not fully inserted, the paper P on the lift plate 22 does not come into contact with the paper feed roller 24 even when the lift plate 22 is raised. A new problem has arisen that the drawer cannot be transported.

  The present invention has been made in view of such a conventional problem, and the object of the present invention is to detect the presence / absence of paper on the manual feed tray even if a paper return phenomenon occurs, and An object of the present invention is to provide a paper feeding device and an image forming apparatus capable of reliably feeding paper when there is paper on a manual feed tray.

  According to the present invention, a paper tray for placing paper, a paper feed roller that pulls out and transports paper on the paper tray, and a position that is in pressure contact with the paper feed roller in synchronization with the rotation of the paper feed roller. And a control unit that controls the rotation of the paper feed roller. The paper feed device includes a lift plate that moves to a position where the paper feed is performed, a detection unit that detects the presence or absence of paper on the paper tray, and a control unit that controls rotation of the paper feed roller. The paper detection position is located downstream of the vertical line descending from the central axis of the paper feed roller in the paper transport direction, and the control means detects the absence of paper on the paper tray during the paper feed. In this case, the paper feed roller is rotated for a predetermined time, and when the detection unit detects again that there is no paper on the paper tray, it is determined that there is no paper on the paper tray, and the paper feed roller is stopped. Paper feeding device It is.

  According to the present invention, there is provided an image forming apparatus comprising the paper feeding device described above.

  In the paper feeding device and the image forming apparatus of the present invention, the control unit rotates the paper feeding roller for a predetermined time when the detecting unit detects that there is no paper on the paper tray during paper feeding. Even if the phenomenon occurs, if there is paper on the manual feed tray, the paper is pulled out by the rotation of the paper feed roller and the presence of the paper is detected by the detection means, and the absence of paper is detected erroneously. There is no longer to do. In addition, since the paper detection position of the detection means is located downstream of the vertical line drawn from the central axis of the paper feed roller in the paper transport direction, if the presence of paper is detected by the detection means, the paper feed roller When the elevating plate moves to a position where it is pressed against the sheet, the sheet comes into contact with the sheet feed roller, and the sheet is reliably pulled out and conveyed from the manual feed tray.

  Hereinafter, the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.

  FIG. 1 is a vertical sectional view showing an embodiment of a sheet feeding device and an image forming apparatus according to the present invention. The image forming apparatus in this figure is a so-called in-body discharge type image forming apparatus. A paper discharge space 3 having an opening on the front side is formed at a substantially central portion in the vertical direction of the apparatus main body 1. On the bottom surface of the paper discharge space 3, a tray 87 for placing paper to be discharged is integrally formed with the casing. On the other hand, a reading mechanism 91 for reading a document is built in the upper side of the paper discharge space 3, and an image forming mechanism is built in the lower side of the paper discharge space 3.

  The image forming mechanism will be described. The surface of the photosensitive drum 70 is uniformly charged positively or negatively by the charging device 71. On the other hand, a document (not shown) is placed on the document placing table 90, and the image data is read by the reading device 91. The read image data is written on the surface of the photosensitive drum 70 by a laser scanner (exposure device) 72, and an electrostatic latent image is formed on the surface of the photosensitive drum 70. Specifically, in the case of the reverse development method, the charge corresponding to the image is removed, and in the case of the regular development method, the charge corresponding to the background is removed to form an electrostatic latent image. Next, the electrostatic latent image on the photosensitive drum 70 is visualized with toner by the developing device 73. At this time, the charging polarity of the toner is the same as the charging polarity of the photosensitive drum 70 in the case of the reversal development method, and is opposite to the charging polarity of the photosensitive drum 70 in the case of regular development.

  On the other hand, the paper P stored in the paper feed cassette 81 is pulled out by the pickup roller 82, sandwiched between the paper feed roller 83 and the separating roller 84, and sent to the conveyance path. Then, the registration roller pair 80 feeds the paper P to the transfer unit at the timing when the toner image on the photosensitive drum 70 reaches the transfer unit. In the transfer portion, the sheet P is sandwiched between the photosensitive drum 70 and the transfer roller 74, and a charge having a polarity opposite to the toner charging polarity is applied to the transfer roller 74. Toner image moves onto the paper P. The toner remaining on the photosensitive drum 70 without moving onto the paper P is removed and collected by the cleaning roller 75. On the other hand, the paper P on which the toner image is placed is conveyed to the fixing roller pair 85. Here, the toner image is heated and pressurized by the fixing roller pair 85 and fixed on the paper P. Then, the paper P is sent to the discharge roller pair 86 and discharged to the tray 87.

  On the other hand, the paper P placed on the manual feed tray 21 is sandwiched between the paper feed roller 24 and the separation pad 25 and sent to the registration roller pair 80. After that, it passes the same route as the above-mentioned transport route. FIG. 2 shows an enlarged cross-sectional view of a paper feeding portion using the manual feed tray 21. As shown in FIG.

  2 includes a manual feed tray 21 attached to the apparatus main body 1 (shown in FIG. 1) so as to be openable and closable around a shaft 20, a paper feed roller 24 that draws and conveys the paper P to the transport path, The separation pad 25 that separates and conveys the paper by being brought into pressure contact with the paper feed roller 24, the elevating plate 22 biased in the direction of the paper feed roller 24 by the push spring 23, and the presence or absence of paper on the manual feed tray 21 are detected. Sensor (detection means) 41. As shown in FIG. 7, the elevating plate 22 is moved to a position where it is pressed against the paper feed roller 24 and a position where it is separated by the action of the cam 60 mounted on the rotation shaft 241 of the paper feed roller 24 and the push spring 23. To do. The detection position of the sensor 41 is located downstream of the vertical line (broken line in the figure) drawn from the rotation axis of the paper feed roller 24 in the paper transport direction. In this device 2, a mechanical sensor is used as the sensor 41, but an optical sensor may of course be used. Moreover, although the combination of the push spring 23 and the cam 60 (illustrated in FIG. 7) is used as the moving mechanism of the elevating plate 22, for example, a solenoid or a motor may be used.

  A control block of the sheet feeding device 2 is shown in FIG. A CPU (control means) 50 that controls the drive of the apparatus including the paper feed roller 24 is connected to a ROM 51 that stores a program for controlling the image forming apparatus and a RAM 52 that is a program execution area. The CPU 50 is connected to a motor (not shown) for driving the paper feed roller 24, and a sensor 41 and a sensor 42. An on / off signal is sent from the sensor 41 and the sensor 42 to the CPU 50, and the CPU 50 is based on this signal. Performs rotation control of a motor (not shown) that rotates the paper feed roller 24.

  As shown in FIG. 4, when paper P is fed from the paper feeder 2 having such a structure, the manual feed tray 21 is opened from the apparatus main body 1 (shown in FIG. 1) and is placed on the manual feed tray 21. The paper P is placed. At this time, the paper P is pushed deeply into the lifting plate 22 so that the front end of the paper P pushes down the sensor 41. Next, when an image formation start signal is input from a panel (not shown) of the apparatus main body 1 (shown in FIG. 1), the paper feed roller 24 starts to rotate. Then, as described above, the lift plate 22 is pushed upward by the push spring 23 (FIG. 4A). Then, several sheets of paper are pulled out from the upper and lower plates 22 by the paper feed roller 24, separated by the separation pad 25, and only the uppermost paper is conveyed to the registration roller pair 80.

  As shown in FIG. 4B, the lifting plate 22 moves away from the paper feed roller 24 in synchronization with the leading edge of the sheet conveyed to the registration roller pair 80 being sandwiched between the registration roller pair 80. Moving. As a result, a phenomenon of returning to the sheet which is not conveyed to the registration roller pair 80 and is sandwiched between the sheet feeding roller 24 and the separation pad 25 occurs. In the conventional apparatus, if the presence of the sheet P is not detected by the sensor 41, the sheet feeding roller 24 is stopped because there is no sheet on the manual feed tray 21. However, in the paper feeding device of the present invention, even when the presence of the paper P is not detected by the sensor 41, the paper feeding roller 24 is further rotated for a predetermined time. As a result, as shown in FIG. 5C, the sheet P is pulled out by contacting the sheet feeding roller 24 by the raising of the elevating plate 22, the sensor 41 is turned on, and the sheet is fed without stopping. . On the other hand, when the paper on the manual feed tray 21 is really exhausted, the sensor 41 remains off even after the paper feed roller 24 continues to rotate for a predetermined time. Is stopped, and a display indicating that there is no paper is displayed on the display unit (not shown).

  There is no particular limitation on the time for which the paper feed roller 24 is continuously rotated after the sensor 41 no longer detects the presence of the paper, and the leading edge of the paper when the paper returns in the direction opposite to the paper transport direction due to the return phenomenon. Although it may be determined as appropriate from the distance between the position and the sensor 41, the peripheral speed of the paper feed roller 24, etc., about several tens to several hundreds msec is generally sufficient.

  FIG. 5 shows a flowchart of the operation of the sheet feeding device described above. When image formation is started, it is first determined whether or not the sensor is on, that is, whether or not there is paper on the manual feed tray (step S101). If the sensor is off, a message indicating that there is no paper in the manual feed tray is displayed on the display unit (step S102). On the other hand, when the sensor is on (step S101), the paper feed roller starts to rotate (step S103).

  Then, it is determined whether or not a predetermined number of images have been formed (step S104). If a predetermined number of images have been formed, the paper feed roller is stopped (step S111), and the paper feed operation ends. On the other hand, if a predetermined number of images have not been formed (step S104), it is determined whether the sensor is on (step S105). If the sensor is on, this loop is repeated until the predetermined number of images have been formed. It is.

  When the sensor is off (step S105), the timer starts and the rotation of the paper feed roller is continued until the timer exceeds Xmsec (steps S106 and S107). When Xmsec has elapsed, the timer is reset (step S108), and it is determined whether the sensor is on (step S109). When the sensor is turned on, the paper is returned from the paper return phenomenon to the detection position, and the paper feeding operation is continued until the formation of a predetermined number of images is completed (step S104). On the other hand, if the sensor is off even after rotating the paper feed roller for Xmsec (step S109), a message indicating that there is no paper in the manual feed tray is displayed (step S110), and the paper feed roller is stopped ( Step S111), the paper feeding operation is terminated.

  As described above, the manual feed tray is exemplified as the paper tray in the embodiment described above, but there is no particular limitation as long as the paper tray is configured such that the paper is placed in a substantially horizontal state and the paper is conveyed in a substantially vertical direction.

1 is a schematic configuration diagram illustrating an example of a sheet feeding device and an image forming apparatus according to the present invention. FIG. 2 is an enlarged schematic configuration diagram of a paper feeding portion in FIG. 1. It is a control block diagram of the apparatus of FIG. It is a figure explaining the paper feeding operation | movement of the paper feeding apparatus of FIG. 3 is a flowchart of a sheet feeding operation of the sheet feeding device in FIG. 2. FIG. 6 is a diagram illustrating a paper return phenomenon in a paper feeding device. It is a figure explaining the movement of the raising / lowering board by a cam and a press spring. It is a figure which shows an example of the conventional paper feeder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Apparatus body 2 Paper feeder 21 Manual feed tray (paper tray)
22 Lifting Plate 23 Push Spring 24 Paper Feed Roller 25 Separation Pad 41 Sensor (Detection Means)
42 sensor 60 cam 80 registration roller pair

Claims (2)

The paper tray for loading paper, the paper feed roller that pulls out and transports the paper on the paper tray, and the position that presses the paper feed roller and the position that moves away are synchronized with the rotation of the paper feed roller. A sheet feeding device comprising an elevating plate, a detection unit for detecting the presence or absence of a sheet on a sheet tray, and a control unit for controlling rotation of the sheet feeding roller,
The paper detection position by the detection means is located downstream of the vertical line drawn from the central axis of the paper feed roller in the paper transport direction,
The control means rotates the paper feed roller for a predetermined time when the detection means detects the absence of paper on the paper tray during paper feeding, and when the detection means detects the absence of paper on the paper tray again. A paper feeding device that judges that there is no paper on the paper tray and stops the paper feeding roller.   An image forming apparatus comprising the sheet feeding device according to claim 1.

Images