JP3717465B2 - Sheet separating and feeding apparatus, and image reading apparatus and image forming apparatus provided with the apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet separating and feeding apparatus that separates sheets so as not to be double-fed, and an image reading apparatus that includes the sheet separating and feeding apparatus and reads an image of a sheet fed by the sheet separating and feeding apparatus. And an image forming apparatus that includes the image reading apparatus and forms an image on a sheet fed by a sheet separating and feeding apparatus.
[0002]
[Prior art]
2. Description of the Related Art In recent years, image forming apparatuses such as printers, copiers, facsimile machines, and multi-function machines have a sheet separation and feeding device that separates sheets from a sheet bundle one by one and feeds them to an image forming unit. Further, the document reading apparatus, which is an image reading apparatus, also includes a sheet separating and feeding apparatus that separates sheets one by one from the sheet bundle and feeds them to the image reading unit. As such a sheet separating and feeding apparatus, a device that employs a separation roller system capable of separating a sheet with high reliability from a low speed to a high speed is widely used.
[0003]
The separation roller type sheet separating and feeding device includes a feeding roller that is a feeding rotating body that rotates in the sheet feeding direction, and presses the feeding roller with a predetermined pressure, and in a direction opposite to the sheet feeding direction, in other words, Sheets are separated and fed one by one by a roller pair which is a pair of rotating bodies with a separating roller (retarding roller) which is a separating rotating body that rotates in the direction to return the sheets.
[0004]
Usually, the separation roller is rotated by transmitting the rotational force of a motor driving another transport system through a rotational force transmission path such as a gear or a belt. A torque limiter that generates slip at a specified load or higher is provided in the drive transmission path of the separation roller. This torque limiter is normally operated by a load composed of a frictional force between the feed roller and the sheet. The separation roller is configured to rotate (follow) the sheet by a torque limiter and convey one sheet.
[0005]
On the other hand, when a plurality of overlapped sheets enter the nip between the feed roller and the separation roller that are in pressure-contact with each other, the sheet that contacts the feed roller is conveyed in the feed direction by sliding between the sheets, and contacts the separation roller side. The sheet is returned by the reverse rotation of the separation roller.
[0006]
In order to satisfy the sheet conveyance and sheet separation conditions in the sheet separating and feeding apparatus having the above-described configuration, it is necessary to satisfy the following theoretical formula.
[0007]
F1> F3> F4> F2 (1)
F5> F4 (2)
here,
F1 = μ1 × N: force that the feed roller advances the sheet
F2 = μ2 × N: force with which the sheets are brought together
F3 = μ3 × N: force by which the separation roller stops the sheet
F4 = T ÷ r: force that the separation roller rotates
F5 = μ4 × N: force by which the feed roller turns the separation roller
μ1: Friction coefficient between feed roller and sheet
μ2: Friction coefficient between sheets
μ3: Friction coefficient between separation roller and sheet
μ4: Friction coefficient between feed roller and separation roller
N: Pressure applied to the separation roller
r: radius of separation roller
T: idling torque of torque limiter
And
[0008]
[Problems to be solved by the invention]
However, in the conventional sheet separating and feeding apparatus, the sheet is affected by static electricity or the frictional force between the sheets is large, so that F2 (the force with which the sheets are brought together) increases and F4 (with the separation roller). If the force exceeds the turning force), the limit value of the torque limiter is constant, so that the separation roller may be rotated along the sheet bundle, and the rotated sheets may not be completely separated and may be double fed.
[0009]
If the limit value of the torque limiter is set to a high value, the sheets will not be sent in an overlapping manner. If only one sheet is sent, the separation roller will not follow the one sheet and follow it. There was a risk of rubbing and scratching the sheet. In particular, when the sheet is thin, the thin sheet may be torn.
[0010]
The present invention makes it possible to vary the rotational torque of the separation rotator by driving the separation rotator with a drive motor that is different from the drive motor that drives the feed rotator. By setting the upper limit so that it is weaker than the rotational torque of the body, even if it is a sheet with a high friction coefficient, it is possible to reliably separate the multi-feed sheet, and even a thin sheet can be conveyed without being damaged The object is to provide a separating and feeding apparatus.
[0011]
SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading apparatus that includes a sheet separating and feeding device in an apparatus main body and reliably reads an image of a sheet that is reliably fed one by one from the sheet separating and feeding device.
[0012]
SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that includes a sheet separating and feeding apparatus in an apparatus main body and that reliably forms an image on a recording medium that is reliably fed sheet by sheet from the sheet separating and feeding apparatus. It is said.
[0013]
[Means for Solving the Problems]
  In order to achieve the above object, the sheet separating and feeding apparatus of the present invention includes:
  Sheet placing means for placing a plurality of sheets; and
  Sheet feeding means for feeding a sheet placed on the sheet placing means;
  A feed rotator for feeding the sheet in the sheet feeding direction of the sheet feeding means;
  A separation rotator that is disposed so as to be in pressure-contact with the feed rotator and is capable of reverse-feed rotation to return a sheet in a direction opposite to the sheet feeding direction;
  First driving means for driving the feed rotating body;
  Second driving means for driving the separation rotating body;
  Control means for controlling the second drive means;
  Sheet thickness detecting means for detecting the thickness of the conveyed sheet;With
  The first drive means and the second drive means are different drive means, and a rotational torque of the reverse rotation of the separation rotator is set smaller than a rotation torque of the feed rotator, and the separation When the rotating body is in contact with the feeding rotating body directly or with one sheet interposed, the rotating body rotates with the feeding rotating body.And
  The control means controls the second drive means such that the greater the thickness of the sheet detected by the sheet thickness detection means, the greater the rotational torque of the separation rotating body.
[0016]
  The sheet separating and feeding apparatus according to the present invention includes storage means for storing the thickness of one sheet detected by the sheet thickness detection means, and the control means is configured to store the current sheet detected by the sheet thickness detection means. When the thickness exceeds the thickness of the sheet stored in the storage means, the second torque is increased so that the rotational torque of the separation rotating body is increased.DriveControl means.
[0017]
  To achieve the above objective,The sheet separating and feeding apparatus of the present invention is
  Sheet placing means for placing a plurality of sheets; and
  Sheet feeding means for feeding a sheet placed on the sheet placing means;
  A feed rotator for feeding the sheet in the sheet feeding direction of the sheet feeding means;
  Arranged so as to come into pressure contact with the feed rotator and opposite to the sheet feeding direction
A separation rotating body capable of reverse rotation and returning the sheet in the direction,
  First driving means for driving the feed rotating body;
  Second driving means for driving the separation rotating body;
  Control means for controlling the second drive means;
  Sheet size detection means for detecting the sheet sizeWhen,With
  The first drive means and the second drive means are different drive means, and a rotational torque of the reverse rotation of the separation rotator is set smaller than a rotation torque of the feed rotator, and the separation When the rotating body is in contact with the feeding rotating body directly or with one sheet interposed, the rotating body rotates with the feeding rotating body,
  The control means controls the second drive means such that the larger the sheet size detected by the sheet size detection means, the greater the rotational torque of the separation rotator.
[0018]
  In order to achieve the above object, the sheet separating and feeding apparatus of the present invention includes:
  Sheet placing means for placing a plurality of sheets; and
  Sheet feeding means for feeding a sheet placed on the sheet placing means;
  A feed rotator for feeding the sheet in the sheet feeding direction of the sheet feeding means;
  A separation rotator that is disposed so as to be in pressure-contact with the feed rotator and is capable of reverse-feed rotation to return a sheet in a direction opposite to the sheet feeding direction;
  First driving means for driving the feed rotating body;
  Second driving means for driving the separation rotating body;
  Control means for controlling the second driving means to change the reverse feed rotational speed of the separation rotating body;
  Sheet thickness detecting means for detecting the thickness of the conveyed sheet;With
  The first driving means and the second driving means are different driving means, and when the separation rotating body is in contact with the feeding rotating body directly or with one sheet interposed therebetween, Rotate with the feed rotating bodyAnd
  The control means controls the second drive means so that the reverse rotation speed of the separation rotating body increases as the thickness of the sheet detected by the sheet thickness detection means increases.It is supposed to be.
[0020]
The sheet separating and feeding apparatus according to the present invention includes storage means for storing the thickness of one sheet detected by the sheet thickness detection means, and the control means is configured to store the current sheet detected by the sheet thickness detection means. When the thickness exceeds the thickness of the sheet stored in the storage unit, the second driving unit is controlled so that the reverse rotation speed of the separation rotating body is increased.
[0021]
  To achieve the above objective,The sheet separating and feeding apparatus of the present invention is
  Sheet placing means for placing a plurality of sheets; and
  Sheet feeding means for feeding a sheet placed on the sheet placing means;
  A feed rotator for feeding the sheet in the sheet feeding direction of the sheet feeding means;
  A separation rotator that is disposed so as to be in pressure-contact with the feed rotator and is capable of reverse-feed rotation to return a sheet in a direction opposite to the sheet feeding direction;
  First driving means for driving the feed rotating body;
  Second driving means for driving the separation rotating body;
  Control means for controlling the second driving means to change the reverse feed rotational speed of the separation rotating body;
  Sheet size detection means for detecting the sheet sizeWhen,With
  The first driving means and the second driving means are different driving means, and when the separation rotating body is in contact with the feeding rotating body directly or with one sheet interposed therebetween, Rotate around the feed rotating body,
  The control means controls the second driving means so that the reverse rotation speed of the separation rotator increases as the sheet size detected by the sheet size detection means increases.
[0025]
  In order to achieve the above object, an image reading apparatus of the present invention includes:
  A sheet placing means for placing a plurality of sheets on which images are formed; and
  Sheet feeding means for feeding a sheet placed on the sheet placing means;
  A feed rotator for feeding the sheet in the sheet feeding direction of the sheet feeding means;
  A separation rotator that is disposed so as to be in pressure-contact with the feed rotator and is capable of reverse-feed rotation to return a sheet in a direction opposite to the sheet feeding direction;
  First driving means for driving the feed rotating body;
  Second driving means for driving the separation rotating body;
  An image reading means for reading an image of the sheet fed by the feed rotator and the separation rotator;
  Control means for controlling the second drive means;
  Sheet thickness detecting means for detecting the thickness of the conveyed sheet;With
  The first driving means and the second driving means are different driving means, and a rotational torque of the reverse rotation of the separation rotator is set smaller than a rotation torque of the feed rotator, and the separation When the rotating body is in contact with the feeding rotating body directly or with one sheet interposed, the rotating body rotates with the feeding rotating body.And
  The control means controls the second driving means so that the greater the thickness of the sheet detected by the sheet thickness detection means, the greater the rotational torque of the separation rotating body.It is supposed to be.
[0028]
  The image reading apparatus of the present invention includes storage means for storing the thickness of one sheet detected by the sheet thickness detection means, and the control means is the current sheet thickness detected by the sheet thickness detection means. However, when the thickness of the sheet stored in the storage means is exceeded, the second torque is increased so that the rotational torque of the separation rotating body is increased.DriveControl means.
[0029]
  To achieve the above objective,The image reading apparatus of the present invention includes:
  A sheet placing means for placing a plurality of sheets on which images are formed; and
  Sheet feeding means for feeding a sheet placed on the sheet placing means;
  A feed rotator for feeding the sheet in the sheet feeding direction of the sheet feeding means;
  A separation rotator that is disposed so as to be in pressure-contact with the feed rotator and is capable of reverse-feed rotation to return a sheet in a direction opposite to the sheet feeding direction;
  First driving means for driving the feed rotating body;
  Second driving means for driving the separation rotating body;
  An image reading means for reading an image of the sheet fed by the feed rotator and the separation rotator;
  Control means for controlling the second drive means;
  Sheet size detection means for detecting the sheet sizeWhen,With
  The first drive means and the second drive means are different drive means, and a rotational torque of the reverse rotation of the separation rotator is set smaller than a rotation torque of the feed rotator, and the separation When the rotating body is in contact with the feeding rotating body directly or with one sheet interposed, the rotating body rotates with the feeding rotating body,
  The control means controls the second drive means such that the larger the sheet size detected by the sheet size detection means, the greater the rotational torque of the separation rotator.
[0033]
In order to achieve the above object, an image forming apparatus according to the present invention includes a sheet separating and feeding apparatus that separates and feeds sheets, and an image forming that forms an image on a sheet fed by the sheet separating and feeding apparatus. And the sheet separating and feeding device is any one of the above sheet separating and feeding devices.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
A sheet separating and feeding apparatus according to an embodiment of the present invention, and an image reading apparatus and an image forming apparatus including the apparatus will be described with reference to the drawings.
[0035]
Examples of the sheet separating and feeding apparatus include a document separating and feeding apparatus that separates and feeds documents one by one, a recording medium separating and feeding apparatus that separates and feeds recording materials one by one. is there.
[0036]
An example of the image reading apparatus is a document reading apparatus. The original reading apparatus has the original separating / feeding apparatus as one of the components in the apparatus main body, and reads an original sent from the original separating / feeding apparatus.
[0037]
Examples of the image forming apparatus include a printer, a copier, a facsimile machine, and a multifunction machine of these. The image forming apparatus has the recording material separating and feeding apparatus as one of the components in the apparatus main body, and forms an image on the recording material sent from the recording material separating and feeding apparatus. ing. Image information formed on the recording material by the image forming apparatus includes image information sent from the outside and image information from a document reading apparatus provided in the apparatus main body of the image forming apparatus.
[0038]
(Image reading device)
A document through type (sheet through type) document reading apparatus which is an example of an image reading apparatus will be described with reference to the drawings. In this document reading device, a document separation and feeding device, which is an example of a sheet separation and feeding device, is mounted on the device body of the document reading device as one of the components of the document reading device, and is supplied from the document reading device. The original is read.
[0039]
FIG. 1 is a cross-sectional view of a document reading apparatus, which is an example of the image reading apparatus of the present invention, along a document transport direction.
[0040]
For example, the document table 2 that is a sheet placing unit is configured such that a bundle of documents, for example, a document P is set by the user. The document table 2 is configured such that the downstream end in the document conveyance direction can move up and down around the rotation fulcrum 2a. The rotating cam 10 moves the document table 2 up and down. The document table motor 3 rotates the rotation cam 10 to move the document table 2 up and down.
[0041]
For example, a pickup roller 4 serving as a sheet feeding unit feeds the document P from the uppermost document in the bundle of documents P on the document table 2 into the document reader main body 101. The electromagnetic solenoid 5 is configured to bring the pickup roller 4 into and out of contact with the uppermost document. The sensor lever 6 detects the presence or absence of a document.
[0042]
For example, a feed roller 7 which is a feed rotating body is configured to further convey the document supplied by the pickup roller 4 to the inside of the apparatus main body 101. In FIG. 1, the feed roller 7 has a shape with a part cut away. However, this is a shape with a cutout for easy understanding of other structures. ing. For example, the separation roller 9 which is a separation rotating body is applied with a rotational force so as to convey the document in the direction opposite to the conveyance direction. The feed roller 7 and the separation roller 9 constitute a rotating body pair.
[0043]
The pre-registration sensor 11 detects passage of a document. The registration roller 12 and the registration driven roller 13 are pressed against each other to correct the skew of the sheet and to feed the original to the reading units 23 and 24.
[0044]
The document thickness detection lever 14 detects the thickness of the document that has been conveyed. The document thickness detection lever 14 in the document reading apparatus 100 according to the present embodiment is installed immediately after the downstream side of the feed roller 7, but may be installed upstream of the feed roller 7. The registration electromagnetic clutch 16 turns on / off the driving of the registration roller 12. The post-registration sensor 17 detects the passage of the document.
[0045]
The conveyance roller pairs 19, 20, 21, and 22 are configured to convey the document. For example, the main motor 18 serving as the first driving means transmits its rotational force to the pickup roller 4, the feed roller 7, the registration roller 12, and the conveyance roller pairs 19, 20, 21, and 22 by a gear or belt (not shown). It is like that.
[0046]
For example, the reading units 23 and 24 as image reading means respectively read image information on the front and back sides of the conveyed document. The document discharge sensor 25 detects that the sent document is discharged from the apparatus main body 101. The static elimination unit 26 is configured to remove static electricity charged on the original. The stacking unit 27 is configured to stack the originals discharged from the conveyance path H.
[0047]
The document stacking tray 30 is configured to receive a large document that does not fit on the document table 2. For example, the separation motor 31 that is the second driving means is a motor that normally rotates the separation roller 9 via a gear or a belt (not shown). In this embodiment, a DC brushless motor that is easy to perform rotation control is used. Yes.
[0048]
The rotational torque of the separation motor 31 is set to be smaller than the rotational torque of the feed roller 7 when the separation roller 9 is in contact with the feed roller 7 installed so as to be in pressure contact with the separation roller 9. For this reason, the separation roller 9 rotates with the rotation of the feed roller 7 when it is in direct contact with the feed roller 7.
[0049]
FIG. 3 is a schematic perspective view of, for example, a document thickness detection unit 202 which is a sheet thickness detection unit that detects the thickness of the document. The document thickness detection unit 202 includes a document thickness detection lever 14 rotatably provided on the document thickness detection lever shaft 303 and a document thickness detection sensor 300. The document thickness detection unit 202 detects the thickness of the document when the document thickness detection sensor 300 detects a rotation amount by which the document thickness detection lever 14 is rotated about the document thickness detection lever shaft 303 according to the thickness of the document. It is to discriminate.
[0050]
The document thickness detection sensor 300 is a photointerrupter, emits light such as infrared rays from the slit 301, receives light passing through the slit 302 by a light receiving element (not shown), and outputs an electric signal according to the amount of light received. Output to the outside.
[0051]
On the other hand, the document thickness detection lever 14 is mounted so as to rotate about the lever shaft 303 as a rotation axis. Therefore, when the document is conveyed, the document hits the side h of the document thickness detection lever 14 and pushes up the side h. Then, it rotates around the document thickness detection lever shaft 303. Along with this operation, the upper portion of the document thickness detection lever 14 rotates in the direction of arrow g in FIG. 3 and blocks the light emitted from the slit 301. If the amount of light entering from the slit 302 is reduced, the amount of light received by the light receiving element is also reduced, so that the electric signal level output from the document thickness detection sensor 300 is reduced.
[0052]
Since the amount of the side h that is pushed up increases as the thickness of the document increases, the amount of rotation of the upper portion of the document thickness detection lever 14 in the direction of the arrow g increases, and the amount of the document thickness detection lever 14 blocking the slit 301 also increases. To do. The light receiving element installed on the slit 302 side lowers the electric signal level correspondingly if the amount of light applied decreases. Therefore, the CPU 207 including an A / D converter, which will be described later, inputs the electrical signal from the document thickness detection unit 202 to the A / D converter, so that the CPU 207 determines the thickness of the document based on the difference in the electrical signal level. can do.
[0053]
The document thickness detection lever 14 operates in the same manner as described above to increase the thickness even when the document is fed double.
[0054]
FIG. 2 is a control block diagram of the document through type document reading apparatus according to the present embodiment.
[0055]
The CPU 207 controls the overall operation of the document through type image reading apparatus 100. The reading units 23 and 24 are configured to perform an original image reading operation in accordance with an instruction from the CPU 207. The document thickness detection unit 202 is configured as shown in FIG. 3 and detects the thickness of the document. The document thickness information detected by the document thickness detection unit 202 is transmitted to the CPU 207 as an electrical signal.
[0056]
The separation motor control unit 203 is configured to control the rotation direction, the rotation speed, and the torque of the separation motor 31 according to a command from the CPU 207. As a motor torque control method, the torque of the separation motor 31 is freely changed by current control and voltage control. Further, the separation motor 31 has a hall element for three phases inside. Since the output of the Hall element of each phase changes in order by the rotation of the separation motor 31, the separation motor control unit 203 can detect this and detect the rotation direction of the separation motor 31. . Information on the rotation direction of the separation motor 31 is transmitted to the CPU 207 by the separation motor control unit 203. Further, since the separation motor 31 is a DC brushless motor, the rotation speed can be changed by pulse control.
[0057]
The separation motor control unit 203 controls the rotation direction of the separation motor 31 so that the separation roller 9 rotates in the direction opposite to the conveyance direction. However, when there is only one document between the separation roller 9 and the feed roller 7, or when there is no document and the separation roller 9 and the feed roller 7 are in direct contact, the rotational torque of the separation roller 9 is increased. 7 is set so as to be smaller than the rotational torque 7, so that when the rotational force of the feed roller 7 is transmitted to the separation roller 9, the separation roller 9 rotates with the feed roller 7.
[0058]
When the rotation direction of the separation roller 9 is changed, the separation motor 31 connected via a gear or a belt (not shown) is also driven and rotated in the reverse direction.
[0059]
When the rotation direction of the separation motor 31 changes, the output order of the Hall elements of each phase installed inside changes, so that the separation motor control unit 203 can know that the rotation direction of the separation motor 31 has changed. Thus, it can be detected that the separation roller 9 is rotating.
[0060]
The main motor control unit 205 controls the driving of the main motor 18. In the document reading apparatus 100 of the present embodiment, an electrical signal of document thickness information output from the document thickness detection unit 202 is also analyzed by the CPU 207 to determine the thickness of the document. The image processing unit 208 performs image processing such as A / D conversion processing and shading processing on the image information read by the reading units 23 and 24.
[0061]
The buffer memory 209 temporarily stores image data that has undergone image processing. The communication unit 210 reads image data from the buffer memory 209 and transfers it to the host computer 211.
[0062]
The host computer 211 is connected to the document-through-type document reading device 100 of the present embodiment, and instructs the document reading device 100 to read an image and the like. The host computer 211 stores image data read by the document reading apparatus 100.
[0063]
The document table motor control unit 212 controls the document table motor 3 that moves the document table 2 up and down so that the uppermost document in the document bundle always comes into contact with the pickup roller 4.
[0064]
For example, a sheet size detection unit 214 serving as a sheet size detection unit detects the size of a document placed on the document table 2. By arranging sensors such as a photo reflector (not shown) installed on the document table 2, the size of the document in the lateral direction (direction intersecting the conveyance direction) is detected.
[0065]
In the above-described configuration, a pair of rotating bodies, for example, a document table 2 that is a sheet placing means, a pickup roller 4 that is a sheet feeding means, a feeding roller 7 that is a feeding rotating body, and a separating roller 9 that is a separating rotating body, for example. The first driving means such as the main motor 18, the second driving means such as the separation motor 31, the CPU 207, the separation motor control unit 203, the document thickness detection unit 202, and the like are a document separation and feeding apparatus. A feeding device 102 is configured. The CPU 207, the separation motor control unit 203, and the document thickness detection unit 202 are parts that control the rotation of the separation motor 31 and are examples of control units. Both the separation motor control unit 203 and the document thickness detection unit 202 are included. Neither or one of them is not necessarily required. The document separating and feeding apparatus 102 is controlled by a CPU 207 that controls the entire document reading apparatus 100, but may be controlled by a CPU (not shown) dedicated to the document separating and feeding apparatus 102. Good.
[0066]
Next, the operation of the document reading apparatus 100 provided with the document separating / feeding apparatus 102 as one of the components in the apparatus main body 101 will be described.
[0067]
When an image reading command is issued from the host computer 211, the document table motor control unit 212 drives the document table motor 3 to press the uppermost document on the document stack loaded on the document table 2 against the pickup roller 4. . At the same time, the main motor 18 and the separation motor 31 also start to rotate. At this time, the rotation speed of the separation motor 31 may be freely changed with respect to the rotation speed of the main motor 18, or may follow the change in the conveyance speed of the main motor 18. It may be changed.
[0068]
When the main motor 18 and the separation motor 31 start to rotate, each roller connected by a gear or a belt (not shown) starts to rotate. Since the pickup roller 4 contacts and separates from the original when the electromagnetic solenoid 5 is turned on / off, when the electromagnetic solenoid 5 is turned on, the pickup roller 4 comes into contact with the uppermost original and starts feeding the original. At this time, due to the friction and static electricity of the uppermost document, the lower document is sent to the uppermost document being conveyed from the document table 2 and enters the nip between the feed roller 7 and the separation roller 9. is there. It is the separation roller 9 that pushes back the document that has been taken in.
[0069]
Here, the operation of the separation roller 9 will be described with reference to FIG. FIG. 4A is a diagram when the lower document P2 enters the nip between the feed roller 7 and the separation roller 9 on the upper document P1. An arrow A in the figure indicates the document transport direction. At this time, the feed roller 7 rotates in the direction of arrow B, and the separation roller 9 rotates in the direction of arrow C. Therefore, in FIG. 4A, the upper document P1 is conveyed in the conveyance direction by the feed roller 7, and the lower document P2 is pushed back in the direction of arrow D by the separation roller 9. Accordingly, the feed roller 7 and the separation roller 9 can separate and convey the originals one by one.
[0070]
FIG. 4B is a diagram illustrating a state when only one document P enters the nip between the feed roller 7 and the separation roller 9. FIG. 4B is also a diagram showing a state when the lower document is pushed back from the state of FIG. 4A to become one upper document. In this state, since the separation motor control unit 203 controls the separation motor 31 so that the rotation torque of the separation roller 9 becomes weaker than the rotation torque of the feed roller 7, the rotation force of the feed roller 7 is separated. The separation roller 9 is transferred to the roller 9 and rotates with the feed roller 7. In other words, the separation roller 9 rotates following the feed roller 7. Even when there is no document and the feed roller 7 and the separation roller 9 are in contact, the separation roller 9 rotates following the feed roller 7.
[0071]
When the original is conveyed and approaches the reading units 23 and 24, the reading units 23 and 24 start an image reading operation. The read image information is subjected to image processing by the image processing unit 208 and sent to the host computer 211 via the buffer memory 209 and the communication unit 210.
[0072]
On the other hand, the read original is discharged from the conveyance path H and stacked on the discharge stacking unit 27.
[0073]
As described above, in the document separating and feeding apparatus 102 according to the present embodiment, the separation motor 31 that rotates the separation roller 9 is separated from the main motor 18 that rotates the feed roller 7. If there is an overlap, the separation roller 9 is reliably rotated in the direction to separate the originals. If there is no original to be separated, the separation roller 9 is rotated along with the feed roller 7, so that the conveyance of the originals is obstructed. The original document can be reliably separated and fed without being damaged, scratching the original document, scratching or tearing a thin original document.
[0074]
As the size of the original increases, the contact area between the originals increases and the frictional force increases. For this reason, it is necessary to increase the force for pushing back the brought-in document, and it is necessary to increase the rotational torque of the separation roller. The document size may be determined by the sheet size detection unit 214 and the CPU 207, or the connected host computer 211 may be provided with a document size setting unit (not shown) to set the size.
[0075]
When the document size is determined, the separation motor control unit 203 changes the rotational torque of the separation motor 31 according to the document size. The document separating and feeding apparatus 102 according to the present embodiment can control the rotational torque of the separation roller 9 by the separation motor control unit 203, so that the rotational torque can be increased as the document size increases. However, the upper limit value of the rotational torque of the separation motor 31 must be limited to a value that the separation roller 9 rotates with the feed roller 7.
[0076]
As described above, the document separating and feeding apparatus 102 according to the present embodiment can adjust the rotational torque of the separation roller 9 according to the difference in document size. The separation failure caused by the difference in size can be improved, and the document can be reliably separated and fed.
[0077]
Furthermore, the document separating and feeding apparatus 102 according to the present embodiment can detect the thickness of the document and adjust the rotational torque of the separation roller 9 according to the thickness. The thickness of the originals may be different when the originals are overlapped with each other, or the thickness of one original may be different from the thickness of the other originals. It can be adapted to the case.
[0078]
FIG. 6A is a diagram showing a double feed state when the lower document P2 overlaps the upper document P1 and enters the nip between the feed roller 7 and the separation roller 9. FIG. In this double feed state, when the frictional force on the document surface is strong or when static electricity is accumulated, the documents are brought into close contact with each other, and the separation roller 9 cannot separate the lower document P2 from the upper document P1. This occurs when the lower document P2 is rotated following the movement of the document P2. That is, it occurs when the rotational torque of the separation roller 9 loses the adhesion between the originals.
[0079]
In view of this, the document separating and feeding apparatus 102 according to the present embodiment detects the thickness of the document during the document separation operation, and gradually increases the rotational torque of the separation motor 31 when there is a possibility of document double feeding. As a result, even a manuscript that is difficult to separate can be reliably separated.
[0080]
The operation of preventing document double feeding in the document separating and feeding apparatus 102 of the present embodiment is described in the document reading apparatus 100 shown in FIG. 1, the control block of the document reading apparatus 100 shown in FIG. 2, the flowchart shown in FIG. This will be explained based on.
[0081]
When the host computer 211 connected to the apparatus main body 101 gives an instruction to start scanning, the CPU 207 and the document table motor control unit 212 start the document table motor 3 to tilt the document table 2 upward. The uppermost document is fed by the pickup roller 4 (S501). The conveyance of the document is started, and the leading edge of the document is conveyed to the feed roller 7 and the separation roller 9 and passes through both rollers (S502).
[0082]
At this time, if the force of the separation roller 9 that pushes back the brought-in document is lost to the adhesion force between the documents, the separation roller 9 can not push back the brought-in document and rotates with the feed roller 7. End up. For this reason, the feed roller 7 and the separation roller 9 convey the document in a double-feed state, and cannot prevent double-feed.
[0083]
Therefore, when the leading end of the document passes through the feed roller 7 and the separation roller 9 and pushes up the document thickness detection lever 14 installed immediately after the downstream side of the feed roller 7, the document thickness detection unit 202 is as shown in FIG. Then, the thickness of the document is detected based on the amount by which the document thickness detection lever 14 is pushed up (S503). When the document is fed double, the thickness detected by the document thickness detection unit 202 also increases. Next, an electrical signal of document thickness information is sent from the document thickness detection unit 202 to the CPU 207. The CPU 207 determines whether or not the original thickness is within a specified value (S504). This specified value may be set in advance, or thickness information detected when one document is used may be used. This set value or thickness information is stored in, for example, the RAM 207a which is a storage unit in the CPU 207.
[0084]
Here, if the detected thickness is within the specified value, the CPU 207 determines that the document is not double-fed and leaves the rotational torque of the separation motor as it is. On the other hand, if the specified value is exceeded, the rotational torque of the separation roller 9 is insufficient and it is determined that the document being fed is not separated, and the separation motor control unit 203 rotates the separation motor 31. Increase the torque. As a result, the force to push back the document on the separation roller 9 is increased (S506). However, the rotational torque of the separation motor 31 must be limited to such an extent that the separation roller 9 loses the rotational force of the feed roller 7 and rotates (S505). Here, when the brought-in original is pushed back by the separation roller 9, the original detected by the original thickness detecting unit 202 becomes thin (S507), and it can be seen that the original can be separated (see FIG. 6B). . The document separating and feeding apparatus 102 can separate and supply the document more reliably by repeating the above operation.
[0085]
Even if a thick original is transported from the beginning without double feeding, the rotational torque of the separation motor 31 increases as described above. However, since the upper limit value of the rotational torque of the separation motor 31 is limited to a value that the separation roller 9 rotates with the feed roller 7, the separation roller 9 can convey a thick original document without any problem.
[0086]
As described above, the document separating / feeding apparatus according to the present embodiment can reliably separate documents in close contact with each other by adjusting the torque of the separation roller 9 according to the thickness of the document and changing the separation force. . Furthermore, a thin original can be conveyed without being damaged.
[0087]
In the document feeder of the above embodiment, the document is separated by changing the rotational torque of the separation roller 9, but the document is separated by changing the reverse rotation speed at which the separation roller 9 reversely feeds the document. May be.
[0088]
That is, the CPU 207 controls the separation motor control unit 203 to increase the reverse rotation speed of the separation roller 9 as the thickness of the document detected by the document thickness detection unit 202 is thicker, thereby reliably It may be separated.
[0089]
In this case, the thickness of one original detected by the original thickness detection unit 202 is stored in the RAM 207a, and the CPU 207 stores the current sheet thickness detected by the original thickness detection unit 202 in the RAM 207a. If the thickness exceeds the thickness of the sheet, the separation motor control unit 203 may be controlled so as to increase the reverse rotation speed of the separation roller 9 to reliably separate the document. If the reverse rotation speed of the separation roller 9 is changed in consideration of the thickness, the thin document is not damaged or torn.
[0090]
Further, the CPU 207 controls the separation motor control unit 203 to increase the reverse rotation speed of the separation roller 9 as the document size detected by the sheet size detection unit 214 is larger, thereby reliably separating the document. May be.
[0091]
(Image forming device)
1 is provided with, for example, an image forming unit which is an image forming unit such as a photosensitive drum instead of the reading units 23 and 24, and a fixing device is provided on the downstream side of the image forming unit. For example, a printer is a device. The original separating / feeding apparatus 102 is configured to supply an original, but if a recording medium is supplied, it can be used as a recording medium separating / feeding apparatus.
[0092]
Accordingly, the printer forms a toner image carried on the photosensitive drum based on the electronic data on the recording medium supplied from the recording medium supply device, and heats and presses the recording medium with a fixing device. An image can be formed on a recording medium. As described above, the sheet separating and feeding apparatus can also be provided in the printer. It can also be provided in a copying machine, a fax machine, and a multifunction machine of these.
[0093]
【The invention's effect】
In the sheet separating and feeding device of the present invention, the separation rotating body is driven by driving means different from the driving means for driving the feeding rotating body, so that the rotational torque of the separating rotating body is weaker than the rotational torque of the feeding rotating body. By setting the upper limit in such a manner, even if the sheet has a high friction coefficient, the multi-feed sheet can be reliably separated, and even a thin sheet can be supplied without being damaged.
[0094]
The image reading apparatus of the present invention includes a sheet separating and feeding device that reliably separates the multi-feed sheets and supplies the sheets without damaging the sheets, so that one sheet is provided from the sheet separating and feeding device. Each sheet is reliably sent, and the sheet image can be read reliably.
[0095]
The image forming apparatus according to the present invention includes a sheet separating and feeding device that reliably separates the multi-feed sheets and supplies the sheets without damaging the sheets. The recording medium is surely sent one by one, and an image can be reliably formed on the recording medium.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of, for example, a document reading device which is a document through type image reading device according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of a control block of the document reading apparatus of FIG.
FIG. 3 is a diagram illustrating an example of a configuration of a document thickness detection unit.
FIG. 4 is a diagram for explaining an operation of, for example, a document separating and feeding apparatus which is a sheet separating and feeding apparatus according to an embodiment of the present invention.
(A) It is a figure when the lower original comes in the nip between the feed roller and the separation roller in the upper original.
FIG. 5B is a diagram illustrating a state when only one document enters the nip between the feed roller and the separation roller.
FIG. 5 is a flowchart illustrating an example of a separation operation of the document reading apparatus.
FIG. 6 is a diagram for explaining a document separating operation based on document thickness detection in the document separating and feeding apparatus according to the embodiment of the present invention.
(A) It is a figure when the lower original comes in the nip between the feed roller and the separation roller in the upper original.
FIG. 5B is a diagram illustrating a state when only one document enters the nip between the feed roller and the separation roller.
[Explanation of symbols]
D Arrow
H Transport path
P Original (sheet)
g Arrow
h Document thickness detection lever side
2 Document table (sheet placement means)
4 Pickup roller (sheet feeding means)
7 Feed roller (feed rotating body)
9 Separation roller (separation rotating body)
14 Document thickness detection lever
18 Main motor (first drive means)
23 Reading unit (image reading means)
24 Reading unit (image reading means)
30 Document stacking tray
31 Separation motor (second drive means)
100 Document reading device (image reading device)
101 Document reader main body
102 Document separation / feed apparatus (sheet separation / feed apparatus)
202 Document thickness detector (sheet thickness detector)
203 Separation motor controller (control means)
205 Main motor controller
207 CPU (control means)
207a RAM (storage means)
208 Image processing unit
214 Sheet size detection unit (sheet size detection means)
300 Document thickness detection sensor
301 slit
302 slit
303 Document thickness detection lever shaft

Claims (10)

Sheet placing means for placing a plurality of sheets; and
Sheet feeding means for feeding a sheet placed on the sheet placing means;
A feed rotator for feeding the sheet in the sheet feeding direction of the sheet feeding means;
A separation rotator that is disposed so as to be in pressure-contact with the feed rotator and is capable of reverse-feed rotation to return a sheet in a direction opposite to the sheet feeding direction;
First driving means for driving the feed rotating body;
Second driving means for driving the separation rotating body;
Control means for controlling the second drive means;
Sheet thickness detecting means for detecting the thickness of the conveyed sheet , and
The first drive means and the second drive means are different drive means, and a rotational torque of the reverse rotation of the separation rotator is set smaller than a rotation torque of the feed rotator, and the separation When the rotating body is in contact with the feeding rotating body directly or with one sheet interposed, the rotating body rotates with the feeding rotating body ,
The control means controls the second drive means so that the rotational torque of the separation rotating body increases as the thickness of the sheet detected by the sheet thickness detection means increases. Feeding device. Storage means for storing the thickness of one sheet detected by the sheet thickness detection means;
The control unit is configured to increase the rotational torque of the separation rotating body when the current sheet thickness detected by the sheet thickness detection unit exceeds the sheet thickness stored in the storage unit. The sheet separating and feeding apparatus according to claim 1 , wherein the second driving unit is controlled. Sheet placing means for placing a plurality of sheets; and
Sheet feeding means for feeding a sheet placed on the sheet placing means;
A feed rotator for feeding the sheet in the sheet feeding direction of the sheet feeding means;
Arranged so as to come into pressure contact with the feed rotator and opposite to the sheet feeding direction
A separation rotating body capable of reverse rotation and returning the sheet in the direction,
First driving means for driving the feed rotating body;
Second driving means for driving the separation rotating body;
Control means for controlling the second drive means;
Comprising a sheet size detection means for detecting the size of the sheet, and
The first drive means and the second drive means are different drive means, and a rotational torque of the reverse rotation of the separation rotator is set smaller than a rotation torque of the feed rotator, and the separation When the rotating body is in contact with the feeding rotating body directly or with one sheet interposed, the rotating body rotates with the feeding rotating body,
The control means controls the second drive means so that the larger the sheet size detected by the sheet size detection means, the larger the rotational torque of the separation rotating body becomes. apparatus. Sheet placing means for placing a plurality of sheets; and
Sheet feeding means for feeding a sheet placed on the sheet placing means;
A feed rotator for feeding the sheet in the sheet feeding direction of the sheet feeding means;
A separation rotator that is disposed so as to be in pressure-contact with the feed rotator and is capable of reverse-feed rotation to return a sheet in a direction opposite to the sheet feeding direction;
First driving means for driving the feed rotating body;
Second driving means for driving the separation rotating body;
Control means for controlling the second driving means to change the reverse feed rotational speed of the separation rotating body;
Sheet thickness detecting means for detecting the thickness of the conveyed sheet , and
The first driving means and the second driving means are different driving means, and when the separation rotating body is in contact with the feeding rotating body directly or with one sheet interposed therebetween, Rotate around the feed rotating body ,
The control means controls the second driving means so that the reverse rotation speed of the separation rotating body increases as the thickness of the sheet detected by the sheet thickness detection means increases. Sheet separation and feeding device. Storage means for storing the thickness of one sheet detected by the sheet thickness detection means;
When the current sheet thickness detected by the sheet thickness detection means exceeds the sheet thickness stored in the storage means, the control means increases the reverse rotation speed of the separation rotating body. The sheet separating and feeding apparatus according to claim 4 , wherein the second driving unit is controlled as described above. Sheet placing means for placing a plurality of sheets; and
Sheet feeding means for feeding a sheet placed on the sheet placing means;
A feed rotator for feeding the sheet in the sheet feeding direction of the sheet feeding means;
A separation rotator that is disposed so as to be in pressure-contact with the feed rotator and is capable of reverse-feed rotation to return a sheet in a direction opposite to the sheet feeding direction;
First driving means for driving the feed rotating body;
Second driving means for driving the separation rotating body;
Control means for controlling the second driving means to change the reverse feed rotational speed of the separation rotating body;
Comprising a sheet size detection means for detecting the size of the sheet, and
The first driving means and the second driving means are different driving means, and when the separation rotating body is in contact with the feeding rotating body directly or with one sheet interposed therebetween, Rotate around the feed rotating body,
The control means controls the second drive means so that the reverse rotation speed of the separation rotating body increases as the sheet size detected by the sheet size detection means increases. Feeding device. A sheet placing means for placing a plurality of sheets on which images are formed; and
Sheet feeding means for feeding a sheet placed on the sheet placing means;
A feed rotator for feeding the sheet in the sheet feeding direction of the sheet feeding means;
A separation rotator that is disposed so as to be in pressure-contact with the feed rotator and is capable of reverse-feed rotation to return a sheet in a direction opposite to the sheet feeding direction;
First driving means for driving the feed rotating body;
Second driving means for driving the separation rotating body;
An image reading means for reading an image of the sheet fed by the feed rotator and the separation rotator;
Control means for controlling the second drive means;
Sheet thickness detecting means for detecting the thickness of the conveyed sheet , and
The first drive means and the second drive means are different drive means, and a rotational torque of the reverse rotation of the separation rotator is set smaller than a rotation torque of the feed rotator, and the separation When the rotating body is in contact with the feeding rotating body directly or with one sheet interposed, the rotating body rotates with the feeding rotating body ,
The image reading device characterized in that the control means controls the second driving means so that the rotational torque of the separation rotating body increases as the thickness of the sheet detected by the sheet thickness detection means increases. apparatus. Storage means for storing the thickness of one sheet detected by the sheet thickness detection means;
The control unit is configured to increase the rotational torque of the separation rotating body when the current sheet thickness detected by the sheet thickness detection unit exceeds the sheet thickness stored in the storage unit. The image reading apparatus according to claim 7 , wherein the second driving unit is controlled. A sheet placing means for placing a plurality of sheets on which images are formed; and
Sheet feeding means for feeding a sheet placed on the sheet placing means;
A feed rotator for feeding the sheet in the sheet feeding direction of the sheet feeding means;
A separation rotator that is disposed so as to be in pressure-contact with the feed rotator and is capable of reverse-feed rotation to return a sheet in a direction opposite to the sheet feeding direction;
First driving means for driving the feed rotating body;
Second driving means for driving the separation rotating body;
An image reading means for reading an image of the sheet fed by the feed rotator and the separation rotator;
Control means for controlling the second drive means;
Comprising a sheet size detection means for detecting the size of the sheet, and
The first drive means and the second drive means are different drive means, and a rotational torque of the reverse rotation of the separation rotator is set smaller than a rotation torque of the feed rotator, and the separation When the rotating body is in contact with the feeding rotating body directly or with one sheet interposed, the rotating body rotates with the feeding rotating body,
The image reading apparatus according to claim 1, wherein the control unit controls the second driving unit such that the larger the sheet size detected by the sheet size detection unit, the larger the rotation torque of the separation rotating body. A sheet separating and feeding device for separating and feeding sheets;
Image forming apparatus for forming an image on a sheet fed by the sheet separating and feeding device,
Said sheet separating and feeding apparatus, an image forming apparatus which is a sheet separating and feeding apparatus according to any one of claims 1 to 6.

Images