JP2007230682A - Paper carrying device and image forming device having the device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper carrying device and an image forming device having the device, capable of further surely preventing paper clogging and paper damage in the middle of carrying caused by oblique paper feeding more than a conventional one. <P>SOLUTION: Oblique paper feeding detecting sensors 22a and 22b are arranged in a direction orthogonal to the paper feeding direction between a paper feeding roller 14 for delivering a paper set in a tray and a cassette and a register roller 16 for adjusting timing when sending out the delivered paper to a processing part for performing various processing of a rear stage. A controller 36 calculates a time difference Δt in the detection timing of the paper by these respective detecting sensors 22a and 22b as an oblique paper feeding detecting value, and corrects oblique paper feeding by increasing and reducing a time up to the stopping operation of the paper feeding roller 14 after the paper abuts on the register roller 16 according to the size of this calculated oblique paper feeding detecting value Δt. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet conveying apparatus that conveys various sheets such as original sheets and printing sheets set in a tray or a cassette to a predetermined position, and an image forming apparatus including the sheet conveying apparatus.

  2. Description of the Related Art Generally, some copying machines, multifunction machines, and the like are provided with an automatic document conveying device for conveying document paper to an image reading unit having a scanner optical system. Further, in these copying machines, multifunction machines, and printers, a printing paper transport device is provided to sequentially transport printing paper to a copying unit and a printing unit. In such a paper transport device such as an automatic document transport device or a printing paper transport device, it is necessary to feed the paper one by one to the transport path by a paper feed roller.

  However, if the paper loaded in the cassette is bent, the paper is wrinkled, or the paper guide is not adjusted to match the paper width and is too wide, The paper cannot be smoothly fed out, and a phenomenon occurs in which the paper is fed obliquely with respect to the paper feeding direction (hereinafter referred to as oblique paper feeding). When such oblique feeding is caused, a problem such as paper jamming in the middle of the conveyance path due to poor paper feeding or damage of the paper occurs.

Therefore, conventionally, in order to eliminate such oblique feeding, timing adjustment is performed when the paper fed by the paper feeding roller is sent to a processing unit that performs various processes such as image reading, transfer, and printing in the subsequent stage. The paper tip is temporarily brought into contact with the registration roller to temporarily stop the feeding, thereby forming a deflection at the paper tip and correcting the skew (skew) of the paper fed obliquely. There is a technique in which a registration roller is driven later to eliminate adverse effects on various processing units on the subsequent stage (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 11-322135

  By the way, the skew of the leading edge of the sheet fed obliquely varies depending on the degree of bending of the sheet, the level of wrinkles attached to the sheet, and the degree of adjustment of the sheet guide. However, in the prior art, this point is not fully taken into account, and the driving of the paper feed roller is always stopped after a certain time after the leading edge of the paper comes into contact with the registration roller.

  For this reason, when the skew of the front end of the sheet is large, the oblique feeding is not sufficiently corrected and divided, and as a result, the oblique feeding state continues to various processing units such as image reading, transfer, printing, etc. In some cases, the sheet is transported, the sheet is jammed and damaged in the transport path, and various processes such as image reading, copying, and printing cannot be performed properly.

  The present invention has been made to solve the above problems, and can more reliably prevent the occurrence of problems such as paper jamming in the middle of conveyance or paper damage due to oblique paper feeding. It is an object of the present invention to provide a possible paper transport device and an image forming apparatus using the paper transport device.

  The paper transport device of the present invention includes a paper feed roller that sequentially feeds paper set in a tray or a cassette, and a processing unit that performs various processes such as image reading, transfer, and printing of the paper fed by the paper feed roller. And an oblique sheet feeding detection sensor disposed between the sheet feeding roller and the registration roller and disposed along a direction orthogonal to the sheet feeding direction, and each of the oblique sheet feeding sensors. A calculation unit that calculates a time difference between detection timings of the paper by the paper feed detection sensor as an oblique paper feed detection value, and the paper abuts the registration roller according to the magnitude of the diagonal paper feed detection value calculated by the calculation unit. And an oblique paper feed correcting means for correcting the oblique paper feed by increasing / decreasing the time until the operation of the paper feed roller is stopped.

  Further, the sheet conveying apparatus of the present invention does not perform the oblique paper feeding correction by the oblique paper feeding correcting means when the oblique paper feeding detection value calculated by the calculating means is greater than or equal to a preset upper limit value. An emergency stop means for immediately stopping the paper feeding operation by the paper feed roller is provided.

  In the paper transport device of the present invention, when the oblique paper feed detection value calculated by the calculating means is equal to or lower than a preset lower limit value, the rotational speed of the paper feed roller is controlled by the oblique paper feed detection sensor. It is characterized by comprising a sheet feed speed control means for increasing the period until the period until is detected.

  An image forming apparatus according to the present invention includes the above-described sheet conveying device.

  According to the present invention, the calculation means calculates the time difference between the detection timings of the sheets by the oblique feed detection sensor as the oblique feed detection value, and the oblique feed correction means calculates the oblique feed detection value calculated by the calculation means. Depending on the size of the sheet, the sheet feeding roller is corrected by increasing or decreasing the time from when the sheet comes into contact with the registration roller until the operation of the sheet feeding roller is stopped.

  For this reason, even if the degree of oblique feeding differs depending on the degree of bending of the paper, the degree of wrinkles attached to the paper, and the degree of adjustment of the paper guide, this can be reliably corrected. . As a result, it is possible to eliminate the adverse effects on the various processing units on the downstream side of the registration roller, and various processing such as paper jams in the middle of the conveyance path, paper breakage, image reading, copying, and printing. It is possible to more reliably prevent the occurrence of problems such as the inability to properly perform the operation.

  Further, according to the present invention, when the above-described oblique paper feed detection value is equal to or greater than a preset upper limit value, it is highly possible that the paper is fed while being bound with a staple, a clip, or the like. The emergency stop means immediately stops the sheet feeding operation by the sheet feeding roller without performing the oblique sheet feeding correction. As a result, the paper is not forcibly fed out by the paper feed roller, so that the paper can be more reliably prevented from being damaged.

  Further, according to the present invention, the paper feed speed control means feeds paper when the oblique paper feed detection value calculated by the calculation means by the paper detection by the oblique paper feed detection sensor is equal to or less than a preset lower limit value. Since the rotation speed of the roller is increased more than the period until the sheet is detected by the oblique paper feed detection sensor, it is possible to avoid the inconvenience that the paper transport speed is constantly reduced due to the oblique paper feed detection process.

  Since the image forming apparatus of the present invention is configured to include the above-described sheet conveying apparatus, it is possible to prevent sheet breakage or apparatus damage due to feeding failure due to oblique sheet feeding, and the image forming processing operation is always performed smoothly. It becomes possible to do.

  FIG. 1 is a perspective view showing an overall configuration of a copying machine as an example of an image forming apparatus according to an embodiment of the present invention, FIG. 2 is a configuration diagram of an automatic document feeder and a document reading device provided in the copying machine, and FIG. FIG. 3 is a configuration diagram illustrating an enlarged main part of an automatic document feeder.

  The copying machine 1 according to this embodiment includes a main body housing 2, a document table 3 is provided on the upper portion of the main body housing 2, and an automatic document conveyance device 4 as a paper conveyance device of the present invention is provided above the document table 3. Is provided. An image reading unit 5 that reads an image of a document sheet is provided in the main body housing 2 below the document table 3. Further, an operation panel 7 is provided on the upper front side of the main body housing 2, and a paper receiving tray 8 for discharging printed paper is provided on the outer side of the main body housing 2.

  On the other hand, a lower part of the main body housing 2 is provided with a paper feeding cassette for stocking printing paper (not shown), and a printing paper transport device for taking out the printing paper from the paper feeding cassette and sequentially transporting it to the image forming unit. It has been. The image forming unit exposes an image of a document read by the image reading unit 5 to a photosensitive drum, a developing unit for forming a toner image on the photosensitive drum, and transfers the toner image to printing paper. It has a transfer section.

  The automatic document feeder 4 also serves as a document cover that opens and closes the document table 3, and includes a document tray 9 on which document sheets are set and a sheet discharge tray that stores document sheets P discharged after image reading processing. 10 is provided. The document tray 9 is provided with a pair of left and right paper guides 12 for slidably holding the document paper in the width direction.

  In the middle of the original paper conveyance path 13 from the original tray 9 to the paper discharge tray 10, a paper feed roller 14, a registration roller 16, a conveyance roller 17, and a discharge roller including a pickup roller 14 a and a paper separation roller 14 b from the upstream side. Each roller of the paper roller 18 is sequentially arranged. An area where the image reading unit 5 faces the conveyance path 13 is an image reading position 21.

  The pickup roller 14a feeds the original paper set on the original tray 9 toward the conveyance path 13, and the paper separation roller 14b separates the original paper fed by the pickup roller 14a one by one. It plays the role of sending it out to the transport path 13. The registration roller 16 is for adjusting timing at the time of reading by the document reading unit 5 by bringing the document sheet fed by the rollers 14 and 15 upstream thereof into contact with and temporarily stopping the document sheet.

  In addition, a plurality (two in this example) of oblique paper feed detection sensors 22a and 22b are arranged along a direction orthogonal to the paper feed direction of the original paper at a downstream position close to the paper separation roller 14b. Yes. Further, a paper feed detection sensor 23 is provided at a downstream position close to the oblique paper feed detection sensors 22a and 22b, and a registration sensor 24 is provided at an upstream position close to the registration roller 16. Yes. A document pressing plate 26 that presses the document sheet in the direction of the document table 3 is provided at a position near the image reading position 21 on the transport path 13.

  In the present example, each of the oblique feed detection sensors 22a and 22b is a diffuse reflection sensor that detects that there is a sheet when the amount of reflected light from the document sheet exceeds a threshold value. It is also possible to use it. In this example, a pair is provided on the left and right, but three or more can be arranged.

  The paper feed detection sensor 23 is used to determine the timing for restarting a paper feed motor 38 to be described later when the end of the original paper sent by the registration roller 16 is detected. The registration sensor 24 is used to determine the timing at which the paper feed motor 38 is stopped when the leading edge of the original paper comes into contact with the registration roller 16.

  On the other hand, the image reading unit 5 includes a light source 28 that irradiates light on the original paper, mirrors 30 to 32 that guide reflected light from the original paper to the CCD 29, and a lens 33 that focuses the reflected light on the CCD 29. .

  FIG. 5 is a block diagram showing a main part of a control system for controlling the operation of the automatic document feeder 4 in the copying machine 1 of this embodiment.

  This control system has a controller 36 composed of a microcomputer or the like. To this controller 36, the oblique paper feed detection sensors 22a and 22b for detecting the oblique paper feed, the paper feed detection sensor 23, and the registration sensor 24 are provided. Each detection output and a signal from an operation button disposed on the operation panel 7 are taken in, and a display 37 including an LCD disposed on the operation panel 7 is connected.

  The controller 36 is connected to a paper feed motor 38 and a registration motor 39, and the operation of the paper feed roller 14 is controlled by the control of the paper feed motor 38, and the operation of the registration roller 16 is controlled by the registration motor 39. The controller 36 also controls the operations of the conveyance roller 17 and the paper discharge roller 18 that constitute the automatic document conveyance device 4. Furthermore, the controller 36 stores information input from the operation panel 7 and the sensors 22a, 22b, 23, and 24, a program for controlling the operation of the automatic document feeder 4, and an oblique feed determination. A memory 40 in which numerical values are stored is connected.

  The controller 36 corresponds to the calculation means, the oblique paper feed correction means, the emergency stop means, and the paper feed speed control means in the claims.

Next, the operation of the copying machine 1 configured as described above, particularly the operation of the automatic document feeder 4 here, will be mainly described as to when the paper feeding is normal and when the oblique paper feeding occurs.
(1) When paper feeding is performed normally When the operator sets the original paper P on the original tray 9 and inputs the number of copies, paper size, etc. through the operation panel 7, the operator operates the start key on the operation panel 7. The controller 36 drives the paper feed motor 38 to synchronously drive the pickup roller 14a and the paper separation roller 14b.

  At that time, the original paper P set on the original tray 9 is not bent or has a large wrinkle, and the paper guide 12 is correctly adjusted to match the width of the paper. 4, the original paper P is normally fed out toward the conveyance path 13 by the pickup roller 14a, and is further prevented from being overlaid by the paper separation roller 14b. One by one is sent to the transport path 13.

  In this way, when paper feeding is performed normally, the leading edge of the original paper P is detected almost simultaneously by the oblique paper feed detection sensors 22a and 22b, so that both oblique paper feed detection is performed as shown in FIG. The time difference Δt hardly occurs in the detection outputs of the sensors 22a and 22b. For this reason, since the time difference Δt is equal to or smaller than a preset lower limit value Δtmin (Δt <Δtmin), the controller 36 determines that there is no oblique paper feeding, and increases the rotation speed of the paper feeding motor 38 to increase the original document. The conveyance time of the paper P is shortened.

  Next, the controller 36 stops the feeding of the original paper P by stopping the paper feed motor 38 after a predetermined time T0 has elapsed from the time when the leading edge of the original paper P is detected by the registration sensor 24. In the meantime, the leading edge of the original paper P abuts against the registration roller 16 to cause deflection.

  In this state, when a predetermined time has elapsed and the image reading unit 5 can read the image of the original paper P, the controller 36 activates the registration motor 39. As a result, the document sheet P is conveyed by the registration rollers 16 and passes through the image reading position 21 while being pressed in the direction of the document table 3 by the document pressing plate 26. At this time, the image of the document sheet P is transferred by the image reading unit 5. Read.

The original paper P on which the image has been read by the image reading unit 5 is further conveyed by the conveyance roller 17 and the paper discharge roller 18 and is discharged to the paper discharge tray 10. When the paper feed detection sensor 23 detects the passage of the trailing edge of the original paper P, the controller 36 sets the paper supply motor 38 so that the next original paper P set on the original tray 9 is fed out. restart.
(2) When oblique feeding occurs: A part of the original paper P set on the original tray 9 is bent, the original paper P has a large wrinkle, or the paper guide 12 matches the width of the paper. In the case where the adjustment has not been made correctly as described above, as shown by the solid line in FIG. 4, oblique paper feeding occurs on the original paper P fed out by the paper feeding roller 14.

  When such oblique feeding occurs, the timing at which the leading edge of the sheet is detected by the left and right oblique feeding detection sensors 22a and 22b is different. Therefore, as shown in FIG. A time difference Δt is generated in the detection outputs 22a and 22b. The time difference Δ corresponds to the degree of skew (skew) at the front end of the sheet fed obliquely.

  Therefore, the controller 36 calculates the time difference Δt as an oblique feed detection value, and when the time difference Δt is between a preset lower limit value Δtmin and an upper limit value Δtmax (Δtmin <Δt <Δtmax), the oblique feed is performed. It is determined that paper has occurred.

  Then, the controller 36 does not change the rotation speed of the paper feed motor 38, but stops the paper feed motor 38 from the time (time t1 in FIG. 7) when the registration sensor 24 detects the leading edge of the original paper P (FIG. 7). 7 until time t2) is set to T0 + α. Here, T0 is the above-mentioned fixed time, and α is a correction time set in proportion to the time difference Δt that becomes the above-described oblique paper feed detection value. Therefore, when the time difference Δt is large, the correction time α is also large. The correction time α may be set and registered in the memory 40 as a proportional function of the time difference Δt, or the correction time α is set and registered in the memory 40 step by step according to the magnitude of the time difference Δt. You can also keep it.

Then, within the time T0 + α, the leading edge of the sheet comes into contact with the registration roller 16 and its feeding is temporarily stopped to form a deflection at the leading edge of the sheet. ) Will be corrected. Moreover, since the correction time α is increased / decreased according to the skew of the leading edge of the paper, even if the degree of oblique feeding differs depending on the degree of bending of the original paper P, the degree of wrinkles on the paper, etc. This can be corrected reliably. As a result, the original paper P is jammed in the middle of the conveyance path 13 on the rear side of the registration roller 16, the paper is damaged, or the image reading position 21 cannot be properly read. It can be surely prevented. Then, after the correction of the oblique feeding, when the predetermined time passes and the time when the image reading unit 5 can read the image of the original paper P is reached (time t3 in FIG. 7), the controller 36 activates the registration motor 39. Further, when the time difference Δt is equal to or larger than a preset upper limit value Δtmax (Δtmax ≦ Δt), the controller 36 keeps the original paper P bound with a staple or a clip and causes oblique feeding. The paper feed motor 38 is immediately stopped and the paper feed operation of the original paper P by the paper feed roller 14 is stopped. At the same time, the controller 36 displays a message indicating that a paper feed failure has occurred, for example, a message “please check the original” on the display 37 disposed on the operation panel 7. For this reason, the operator can quickly take action by checking whether or not the original paper P is still bound by a staple or a clip according to this message.

  In this embodiment, the oblique paper feed detection sensors 22 a and 22 b and the paper feed detection sensor 23 are provided separately, but the oblique paper feed detection sensors 22 a and 22 b may be used as the paper feed detection sensor 23. Is possible.

  In the above embodiment, the automatic document feeder 4 has been described as an example of the paper feeder. However, the present invention is not limited to such an automatic document feeder 4 and, for example, print paper can be copied to a copying unit. The present invention can be similarly applied to a printing paper transport device for sequentially transporting to a printing unit.

  Furthermore, in this embodiment, the copying machine 1 has been described as an example of the image forming apparatus. However, the present invention is not limited to such a copying machine 1, and various types of images such as a printer, a multifunction machine, and a facsimile machine. The present invention can be widely applied to a forming apparatus.

1 is a perspective view showing an overall configuration of a copying machine as an example of an image forming apparatus in an embodiment of the present invention. 2 is a configuration diagram of an automatic document feeder and a document reading device provided in the copier. FIG. FIG. 2 is a configuration diagram illustrating an enlarged main part of an automatic document feeder provided in the copier. FIG. 2 is a plan view schematically showing a main part of an automatic document feeder provided in the copier. FIG. 3 is a block configuration diagram showing a main part of a control system that controls the operation of the automatic document feeder in the copier. 5 is a timing chart for explaining an operation when detecting oblique feeding by an oblique feeding detection sensor provided in the automatic document feeder. 6 is a timing chart for explaining an operation when correcting oblique feeding.

Explanation of symbols

1 Copying machine (image forming device)
4 Automatic document feeder (paper feeder)
5 Image Reading Unit 13 Conveying Path 14 Paper Feeding Roller 16 Registration Rollers 22a and 22b Oblique Feeding Detection Sensor 36 Controller (Calculation Means, Oblique Feeding Correction Means, Emergency Stop Means, Feeding Speed Control Means)
38 Paper feed motor 39 Registration motor

Claims (4)

Adjusting timing when feeding paper set in a tray or cassette sequentially and feeding the paper fed by this paper feed roller to a processing unit that performs various processes such as image reading, transfer, printing, etc. In a paper conveyance device provided with a registration roller to perform,
An oblique sheet feeding detection sensor disposed between the sheet feeding roller and the registration roller and disposed along a direction perpendicular to the sheet feeding direction;
Calculating means for calculating a time difference between detection timings of the sheets by the respective oblique paper feed detection sensors as an oblique paper feed detection value;
In accordance with the magnitude of the detected skew feeding value calculated by the calculating means, the skew feeding correction is performed by increasing / decreasing the time from when the sheet comes into contact with the registration roller until the operation of the feeding roller is stopped. Paper feed correction means;
A sheet conveying apparatus comprising:   When the skew feeding detection value calculated by the calculating means is equal to or greater than a preset upper limit value, the sheet feeding operation by the feeding roller is immediately performed without performing the skew feeding correction by the skew feeding correction means. The paper conveying apparatus according to claim 1, further comprising an emergency stop unit that stops the paper.   When the skew feeding detection value calculated by the calculating means is equal to or less than a preset lower limit value, the rotation speed of the feeding roller is set to be shorter than the period until the sheet is detected by the skew feeding detection sensor. The sheet conveying apparatus according to claim 1, further comprising a sheet feeding speed control unit that increases the sheet feeding speed. An image forming apparatus comprising the sheet conveying device according to claim 1.

Images