JP2006151633A - Document feed device, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a document feed device, provided with a carrying means rotation-driven by a stepping motor, and provided with a shading correction white reference function, and an image reading part, in which it is restored without becoming uncontrolled in a case where rotation of the stepping motor is stopped. <P>SOLUTION: As illustrated in Fig.3, this document feed device 21 comprises a CIS 23 where image information recorded on a document is readable. A carrying roller 25 carries the document toward the CIS 23, and it also has the shading correction white reference function to the image information read by the CIS 23. The stepping motor 27 is for driving the carrying roller 25. A motor driver 29 is capable of controlling action of the stepping motor 27. While the carrying roller 25 is carrying out shading correction, rotation control is conducted to the stepping motor 27 in a self-start range A. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

    The present invention relates to a document feeder and an image forming apparatus having the same.

  An image forming apparatus having a copying function and a scanner function, and having an automatic document feeder (Auto document feeder, hereinafter also referred to as ADF) for transporting a document toward a document table provided at the upper part of the main body There is. In this type of image forming apparatus, the ADF is disposed opposite to the document table, and the document is conveyed to a predetermined document reading position on the document table and serves as an image reading unit provided inside the document table. Read by the scanner.

  In this type of conventional image forming apparatus, an ADF provided with an image reading unit separate from the scanner is already known. This image reading unit is generally composed of a contact image sensor (hereinafter referred to as CIS) and is arranged so as to read the surface opposite to the surface of the document read by the scanner. Thus, both sides of the image can be read without performing the document reversing operation.

  The ADF also includes a transport roller for transporting a document during a reading operation, and the transport roller is usually configured to be driven to rotate by a stepping motor.

  By the way, in recent image forming apparatuses, the one that performs shading correction in order to average the reading variation by the reading element of the image forming unit has become the mainstream. In this type of device, specifically, a white shading plate is used for reading by the scanner. However, for reading by the CIS, a white transport roller is used instead of the shading plate due to the limitation of the ADF design space. In many cases, this has a function of shading correction white reference. Such a transport roller may be contaminated on the surface by contacting the document when the document is transported, but even if the surface is soiled, it can be appropriately driven by a stepping motor to perform shading correction appropriately. .

  In addition, ADF generally includes a cover that is part of the casing and that can be freely opened and closed. If the user opens the cover for some reason, the stepping motor rotates for safety reasons. It comes to stop. That is, the conveyance roller may stop even during shading correction.

In addition, as a technique relevant to this, what is shown by patent document 1 and 2 is already proposed, for example.
Japanese Patent Laid-Open No. 10-323088 JP-A-5-155503

  However, in the above-described conventional ADF, when the cover is closed, the signal of the number of pulses of the rotation speed before the stop is supplied to the stepping motor as it is, and there is a possibility that the step-out occurs. When the stepping motor steps out, the shading correction ends incompletely, image reproducibility deteriorates, and inconveniences such as severe abnormal noise occur due to motor rotation failure.

  Therefore, it is conceivable to perform slow-up control on the stepping motor to gradually increase the rotational speed, but it is meaningless to rotate the stepping motor at the same rotational speed as during document conveyance until shading.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a document feeding device that includes a conveying unit that is rotationally driven by a stepping motor and has a function of shading correction white reference and an image reading unit, and performs step-out when the rotation of the stepping motor is stopped. There is to return without.

  According to another aspect of the present invention, the document feeder includes an image reading unit, a conveying unit, a stepping motor, and a motor control unit. The image reading unit can read image information recorded on a document. The conveying unit conveys the document toward the image reading unit and has a function of a shading correction white reference for image information read by the image reading unit. The stepping motor is for driving the conveying means. The motor control unit can control the operation of the stepping motor, and performs rotation control on the stepping motor in the self-starting area while the conveying unit performs shading correction.

  In this device, even if the rotation of the stepping motor is stopped while the shading is being performed, for example, the rotation of the stepping motor is stopped within the self-starting region, the stepping motor can be completely synchronized with the input pulse. Therefore, rotation can be resumed without causing step-out. Therefore, sufficient shading correction can be performed here, and image reproducibility can be improved. In addition, the stepping motor does not require a higher rotation speed than when the document is conveyed, and the rotation speed within the self-starting area is sufficient.

  In the present invention, the self-starting region of the stepping motor is a region unique to the stepping motor and satisfies a torque and frequency that can be started and stopped completely in synchronization with the input pulse. . Further, the self-starting region includes a region that satisfies so-called pulling torque.

  According to a second aspect of the present invention, in the apparatus of the first aspect, the motor control unit controls the rotation of the stepping motor in the through region while the conveying unit conveys the original.

  In this apparatus, when resuming the rotation of the stepping motor that has been stopped at the time of document conveyance, step-out can be avoided by gradually increasing the number of rotations by performing rotation control in the through region.

  Note that the through region refers to a region that satisfies the torque and frequency at which the stepping motor can be controlled at a higher rotational speed than when performing rotational control in the self-starting region. Slow down control is performed.

  According to a third aspect of the present invention, there is provided the document feeding device according to the first or second aspect, further comprising a cover that constitutes a part of the housing and is provided so as to be opened and closed. The stepping motor stops when the cover is opened.

  In general ADF, for safety reasons, when the cover is opened, the rotation of the stepping motor is stopped. However, this configuration tries to restart the rotation of the stepping motor once stopped. In some cases, there is a problem that step-out easily occurs.

  However, in this apparatus, since the stepping motor is controlled to rotate in the self-starting area during shading and in the through area during document conveyance, the stepping motor does not cause a step-out in any case. The rotation can be resumed.

  According to a fourth aspect of the present invention, an image forming apparatus includes a main body unit and a document feeder. The main body has a document table at the upper end. 3. The document feeding device according to claim 1, wherein the document feeding device is attached to the upper end of the main body so as to be freely opened and closed. The main body unit has another document reading unit different from the document reading unit of the document feeding device in a region facing the document feeding device.

  In this apparatus, both sides of a document can be read by image reading units provided on the document feeding device side and the main body side, respectively, and shading correction is performed by a conveying unit for conveying a document. Yes.

  In this apparatus, when the shading correction is being performed, it is sufficient if the stepping motor can be rotated to such an extent that unevenness due to dirt or the like adhering to the surface can be avoided even if the number of rotations is not as high as during document conveyance. For this reason, rotation is resumed in the self-starting region to avoid step-out.

  According to the present invention, even if the rotation of the stepping motor stops during shading correction, such as when the cover is opened, the stepping motor is controlled to rotate within the self-starting region and can be completely synchronized with the input pulse. Rotation can be resumed without stepping out. Therefore, here, sufficient shading correction can be performed to improve image reproducibility. In addition, the stepping motor does not require a higher rotation speed than when the document is conveyed, and the rotation speed within the self-starting area is sufficient.

<Configuration of image forming apparatus>
1 and 2 show an image forming apparatus 1 in which an embodiment of the present invention is adopted.

  The image forming apparatus 1 is a multifunction machine having functions as a copying machine, a printer, a facsimile machine, and a scanner, and includes a main body 3 and an ADF 21.

  The main body 3 is provided with a document table 2 made of contact glass on the upper surface, and has an image reading unit 5, an image forming unit 9, a control unit 11, and other input / output units. . A document reading position R (see FIG. 3) for reading a document fed from the ADF 21 exists on the document table 2.

  The image reading unit 5 is for reading image information of a document on the document table 2, and is arranged inside the document table 2. The image reading unit 5 includes an optical system (not shown), a CCD, and the like.

  The image forming unit 9 forms an image based on image information read by the image reading unit 5, print data sent from the outside, and facsimile reception data. The image forming unit 9 is disposed around the photosensitive drum. The apparatus includes a charging device, an exposure device, a developing device, a transfer device, and the like, and a fixing device disposed downstream thereof.

  The control unit 11 is for performing control of operations of input / output units such as the ADF 21 and the image reading unit 5, image processing, and the like, and includes a microcomputer having a CPU and a memory (not shown). The memory stores various control programs to be executed by the CPU. Further, when the control unit 11 detects that a later-described cover 29 of the ADF 21 is opened, the control unit 11 stops the rotation of the stepping motor 27 via the motor driver 28.

  The image forming apparatus 1 includes an operation panel 31, a communication unit (not shown), a paper feed unit, a paper discharge unit, and the like as other input / output units.

  The operation panel 31 includes a plurality of operation keys 31a and a display unit 31b configured with a touch panel type liquid crystal display. The operation keys include a start key for instructing copying and image reading, a setting key for setting printing conditions, and the like.

  The paper feed unit is for feeding paper from the paper feed cassette 6 or the manual feed tray 8 toward the image forming unit 9.

<ADF>
2 and 3 schematically show the ADF 21.

  The ADF 21 is for feeding documents one by one toward the document reading position R on the document table 2, and is attached to the upper end of the main body 3 so as to be opened and closed. The ADF 21 includes a CIS 23 serving as an image reading unit, a conveyance roller 25, a stepping motor 27, a motor driver 28, and a cover 29.

  The CIS 23 is for reading the image information of the document. Here, the CIS 23 is arranged on the conveyance path P so as to read the image information of the back side of the document read by the image reading unit 5.

  The transport roller 25 is a member for transporting the document transported from the document placing tray 22 toward the paper discharge tray 24, and is disposed to face the CIS 23 via the transport path P. Further, the surface of the conveying roller 25 is made of a white material like the shading plate 33, and while rotating, the image information read by the CIS 23 is used as white reference data to perform shading correction. The shading plate 33 is disposed on the bottom surface of the ADF 21 so as to face the document table 2 and is formed of a white sheet-like member.

  The rotation axis of the stepping motor 27 is connected to the transport roller 25 and receives the input pulse from the motor driver 28 to rotate the transport roller 25.

  The motor driver 28 is an IC (Integrated Circuit) for controlling the operation of the stepping motor 27. Here, the motor driver 28 controls the rotation by outputting an input pulse of the self-starting area to the stepping motor 27 while the shading correction is performed, and to the stepping motor 27 while the document is being conveyed. Rotation is controlled by outputting an input pulse in the through area.

  These self-starting region and through region are portions indicated by A and B in FIG. FIG. 4 is a graph showing the correlation between the torque and frequency inherent in the stepping motor 27, and the boundary line C between the self-starting region A and the through region B is the starting torque (starting characteristic) inherent in the stepping motor 27. Indicates.

  The cover 29 constitutes a part of the housing of the ADF 21 and is provided so as to be freely opened and closed. The user can open the cover and deal with a paper jam or the like.

<Operation of Image Forming Apparatus>
Next, an example of the operation of the image forming apparatus 1 will be described with reference to FIG.

  In the image forming apparatus 1, when a document is supplied from the ADF 21 to perform copying, first, the document is set on the document placing tray 22, printing conditions are set on the operation panel 31 as necessary, and then a start button is pressed. Press to instruct copy (S1). Then, an input pulse in the self-starting area is output from the motor driver 28 to the stepping motor 27 (S2), and the stepping motor 27 starts to rotate (S3), whereby the transport roller 25 rotates and shading correction is performed. (S4).

  At this time, if the cover 29 is opened for some reason (S5), the stepping motor 27 stops rotating (S6). When the cover 29 is closed (S7), the motor driver 28 again supplies the input pulse of the self-activation area to the stepping motor 27 (S2). Then, the stepping motor 27 starts in complete synchronization with the input pulse, starts rotating without being stepped out (S3), and subsequently performs shading correction (S4).

  When the shading correction is completed (S8), the motor driver 28 now outputs an input pulse in the through region (S9), the stepping motor 27 starts rotating (S10), and the rotational speed gradually increases by the slow-up control. When the predetermined number of rotations is reached, the documents are fed one by one from the document placing tray 22 (S11). Here, for the document being fed, first, image information on the front side is read by the image reading unit 5 at the image reading position R, and then image information on the back side is read by the CIS 23 on the downstream side. Image information is read together.

  If the cover 29 is opened for some reason during document feeding (S12), the stepping motor 27 stops rotating (S13). When the cover 29 is closed (S14), an input pulse in the through region is output again from the motor driver 28 to the stepping motor 27 (S9). Then, the stepping motor 27 is subjected to slow-up control according to the input pulse in the through region, starts rotating without being stepped out (S10), and continues to feed the document (S11).

  When the feeding of all the originals is completed (S15), the read image information is subjected to necessary image processing in the control unit 11 (S16), and is output to the image forming unit 9, and the paper cassette 6 or An image is formed on the sheet from the manual feed tray 8, and printing is performed (S17).

  According to the image forming apparatus 1 described above, even if the rotation of the stepping motor is stopped during shading correction, for example, when the rotation of the stepping motor is stopped, the rotation of the stepping motor is controlled within the self-starting area, and the input pulse is completely output. Since it can be synchronized, rotation can be resumed without causing a step-out. Therefore, here, sufficient shading correction can be performed to improve image reproducibility. In addition, the stepping motor does not require a higher rotation speed than when the document is conveyed, and the rotation speed within the self-starting area is sufficient.

<Other embodiments>
(A) A conveyance means is not limited to the conveyance roller of the said embodiment, The roller etc. on which the white conveyance belt was spanned may be sufficient.

  (B) The motor driver may be configured such that the control unit on the main body side performs its function or a part thereof.

  (C) The stepping motor may be configured to stop not only when the cover is opened but also due to other predetermined factors.

  (D) In the above embodiment, instead of performing printing after reading image information of all originals, printing may be performed as soon as image processing of the read image information is completed.

1 is a diagram illustrating an image forming apparatus in which an embodiment of the present invention is employed. FIG. 2 is a block diagram illustrating a configuration of the image forming apparatus. FIG. 2 is a longitudinal sectional view schematically showing a document feeder of the image forming apparatus. 6 is a graph showing frequency and torque characteristics of a stepping motor of the document feeder. 6 is a flowchart for explaining the operation of the image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Document stand 3 Main-body part 5 Image reading part 21 ADF (original document feeder)
25 Stepping motor 27 Motor driver 29 Cover

Claims (4)

An image reading unit capable of reading image information recorded on a document;
Conveying means for conveying a document toward the image reading unit and having a function of a shading correction white reference for image information read by the image reading unit;
A stepping motor for driving the conveying means;
Motor control means capable of controlling the operation of the stepping motor and performing rotation control in a self-starting area for the stepping motor while the conveying means is performing shading correction;
Document feeder with   2. The document feeder according to claim 1, wherein the motor control unit controls rotation of the stepping motor in a through region while the transport unit transports the document. It further comprises a cover that forms part of the housing and that can be opened and closed.
The stepping motor stops when the cover is opened,
The document feeder according to claim 1 or 2. A main body having a document table at the upper end;
The document feeder according to any one of claims 1 to 3, wherein the document feeder is attached to an upper end of the main body so as to be freely opened and closed.
The main body has another image reading unit different from the image reading unit of the document feeder in a region facing the document feeder.
Image forming apparatus.

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