JP2009078903A - Automatic document feeder, image reading device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive automatic document feeder wherein even thin paper can easily go into a nip of an inversion roller and an inversion driven roller member by releasing the inversion driven roller member when a front end and a rear end of a document are overlapped on the inversion roller, and limit on paper thickness with respect to a user can be eliminated, an image reading device with the same, and an image forming device with the image reading device. <P>SOLUTION: The automatic document feeder is equipped with the inversion roller 13 and the confronting inversion driven roller member 13a for separating and conveying the set document one by one from the above and conveying the double-side document, and the inversion roller 13 has a built-in torque limiter. When the front end 1a and the rear end 1b of the document 1 are overlapped on the inversion roller 13, pressure of the inversion driven roller member 13a is released. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an automatic document feeder in an image forming apparatus such as a scanner, a copying machine, and a facsimile, an image reading apparatus to which the automatic document feeder is attached, and an image forming apparatus having the image reading apparatus. .

In a conventional automatic document feeder (ADF) attached to an image reading device of an image forming apparatus, the ADF is large and the documents do not overlap in the conveyance path even at the maximum document size. Actually, thin paper with low stiffness is bounced well at the moment of entering the reversing roller nip and cannot be conveyed.
In order to solve such inconveniences, conventionally, during normal rotation in the normal paper discharge state, the back roller of the paper discharge device is fixed to the conveyance roller and rotates integrally to convey the original and reverse In some cases, a technique for unlocking the transport roller has been proposed (see, for example, Patent Document 1).
In the above-mentioned Patent Document 1, the seating roller of the paper discharge device is fixed to the transport roller and rotates integrally during normal rotation in the normal paper discharge state, and transports the original, and when reversed, A technique is disclosed in which the lock is released and the document is rotated by a conveyed document.
JP 2006-151617 A

However, during normal rotation in the normal paper discharge state, the document is fixed and rotated integrally with the roller to convey the document, and when reversed, the lock to the roller is released and the document to be conveyed is driven to rotate. However, this is not taken into consideration until the leading edge and trailing edge of the document overlap on the roller, and there is a possibility that a conveyance failure may occur.
Therefore, in view of the above-described circumstances, the object of the present invention is to release the reverse driven roller member when the leading end and the rear end of the document overlap on the reverse roller, so that the nip between the reverse roller and the reverse driven roller member can be used even for thin paper. Provided are an automatic document feeder that can easily enter the printer, can eliminate the restriction on the paper thickness for the user, and is inexpensive, an image reading device having the automatic document conveying device, and an image forming apparatus including the image reading device There is to do.

In order to solve the above problems, the invention according to claim 1 is a reverse driven roller member facing a reverse roller for separating and transporting a set original from top to bottom and transporting a double-sided original. And the reverse roller has a built-in torque limiter, and automatically releases the pressure applied to the reverse driven roller member when the leading edge and the trailing edge of the document overlap on the reverse roller. A document conveying device is featured.
The invention according to claim 2 is characterized in that the release timing for releasing the reverse driven roller member is when the leading edge of the document is detected by a sensor disposed upstream of the reverse roller.
The invention described in claim 3 is characterized in that the motor for driving the reverse roller is stopped in the middle of conveyance at the time of reverse switchback.
According to a fourth aspect of the invention, there is provided the automatic document feeder according to any one of the first to third aspects, wherein the reverse driven roller member that has been released is switched to a holding direction during the reverse switchback. To do.
According to a fifth aspect of the present invention, in the image reading apparatus for reading image information while conveying a document, the automatic document conveying device according to any one of the first to fourth aspects is mounted for conveying the document. It features an image reading device.
The invention described in claim 6 is an image forming apparatus that reads image information from a document and transfers an image formed by the image forming unit onto a recording medium from a paper feeding device. An image forming apparatus including a reading device is characterized.

  According to the present invention, when the leading edge and the trailing edge of the document overlap on the reversing roller, the driven roller member is released. Can be eliminated.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing the overall configuration of an automatic document feeder according to the present invention. FIG. 2 is a schematic diagram showing the movement of the document when the automatic document feeder of FIG. 1 is in the duplex mode. FIG. 3 is a schematic diagram showing the movement of the document after reading the second image plane of the automatic document feeder of FIG.
1 to 3, the originals 1 stacked on the original table 2 with the first image surface facing upward are sequentially supplied one by one from the topmost original in response to a signal from an image forming apparatus main body (not shown). The same parts in FIGS. 1 to 3 are denoted by the same reference numerals, and explanations other than necessary for each figure are omitted.
In this embodiment, the automatic document feeder is intended for use in a small (A4 compatible) copying machine. The operation procedure of the automatic document feeder will be described below.
The supplied document 1 front end 1 a is positioned by abutting against the separating member 5. The original document 1 abutted against the separating member 5 is conveyed by the calling member 3 to a separating unit including the sheet feeding member 4 and the separating member 5 and separated one by one from the top. The user can set whether single-sided scanning or double-sided scanning.
The separated document 1 is transported to a transport path having a first transport roller 6 and a first roller driven roller 6a, and then transported to a first transport path having a pre-reading roller 7 and a pre-reading driven roller 7a.

The registration sensor 8 is disposed to detect the leading edge 1a of the document 1, and matches the timing of the passage of the leading edge 1a of the document 1 to the reading unit 9 of the main body and the start of image reading. If the leading edge 1a of the document 1 does not reach the registration sensor 8 even after a predetermined time has passed after feeding the document 1, it is determined that a jam has occurred.
In the case of reading only the first image surface (single-sided mode), the document 1 is read through the second conveyance path having the post-reading roller 11 and the post-reading driven roller 11a after the image information is read by the reading unit 9. The paper is discharged to the paper section 15 (FIGS. 6A and 6B described later).
The paper discharge sensor 10 is arranged upstream of the post-reading roller 11 and the post-reading driven roller 11a in the second transport path. If the leading edge 1a of the document 1 does not reach the discharge sensor 10 even if a certain time has passed, or if the trailing edge 1b of the document 1 does not pass the discharging sensor 10 even if a certain time has elapsed, It has a function for judging a jam. The switching claw 12 is normally held at the position A in the single-sided mode.

In the case of reading the first image surface and the second image surface (double-sided mode) (FIGS. 2 and 3), after reading the first image surface, the leading edge 1a of the document 1 passes through the second conveyance path. The switching claw 12 is shown, for example, in accordance with the timing at which the discharge sensor 10 detects the leading edge 1a of the document 1 reaching the discharge sensor 10 or the timing from when the registration sensor 8 detects the leading edge 1a of the document 1. It is lowered to the position A 'in the figure by a solenoid which is not driving means.
The leading edge 1a of the document 1 passes through the switching claw 12 at the position A 'and is passed through a third conveyance path having the reverse roller 13 and the reverse driven roller 13a (FIG. 6 (c) described later).
The switching claw 12 passes through the paper discharge sensor 10 after the document 1 rear end 1b passes until the document 1 rear end 1b passes the post-read roller (paper discharge roller) 11 and reaches the switching claw 12. After the elapse of time, the solenoid, which is a driving means (not shown), is released to return to the position A.
In this case, the document 1 is in a state in which it has passed the post-reading roller (paper discharge roller) 11, that is, in a state in which the rear end 1 b of the document 1 is sandwiched by the nip between the reverse roller 13 and the reverse driven roller 13 a (described later). (D) of FIG.
From this state, as shown in FIG. 2, after the switching claw 12 is returned, the reversing roller 13 rotates reversely, and the rear end 1b of the original 1 is a post-reading roller (discharge roller) 11 for reading the second original surface. After reading, the ink enters a nip formed by a driven roller (driven roller on discharged paper) 11b (FIG. 6E described later).

A paper discharge sensor 10 is disposed in the second conveyance path downstream of the image reading unit 9. When a certain pulse has elapsed after the discharge sensor 10 detects the leading edge 1b of the document 1, the solenoid is turned on, and the leading edge 1b of the document 1 reaches the nip between the reverse roller 13 and the reverse driven roller 13a.
At this time, the leading edge 1a of the document 1 has not yet passed through the nip between the reverse roller 13 and the reverse driven roller 13a. Therefore, the both-end reversing driven roller 13a-2 in FIGS. 4 and 5 described later is released (FIGS. 6F, 6G, and 6H described later).
The release timing of the reverse driven roller 13a is detected by the paper discharge sensor 10 disposed upstream of the reverse roller 13, and is managed in pulses. As described above, since the paper discharge sensor 10 disposed upstream of the reverse roller 13 detects the leading edge 1a and the trailing edge 1b of the document 1 and performs pulse management, it is possible to prevent conveyance failure.
In this case, the document 1 passes through the fourth conveyance path and the first conveyance path, and the reading unit 9 reads the image information on the second image surface. At the time of reverse switchback, driving of a motor (not shown) applied to the reverse roller 13 is stopped from the middle of conveyance, so that the temperature of the motor and machine can be prevented from rising.

After reading the second image surface, when the document 1 is discharged to the discharge unit 15 through the second conveyance path as it is, the second image surface is stacked downward, and the page order of the document is out of order (described later). As shown in FIG. 6 (i), the front end 1a of the original 1 and the rear end 1b of the original 1 are opposite to the original 1 on the original table 2.
Therefore, the document 1 passes through the second transport path so that the first image surface is stacked downward, and the switching claw 12 is lowered to the position A ′ and transported through the third transport path (described later). As shown in FIGS. 6 (g) and 6 (h), the switching claw 12 returns to the position A, and passes through the fourth transport path, the first transport path, and the second transport path, and the paper discharge section 15 Is discharged ((j) in FIG. 6 to be described later).
After a predetermined pulse after the reverse sensor 14 of the fourth conveyance path shown in FIG. 3 detects the trailing edge 1b of the document 1, the solenoid is turned off, and both-end inverted driven rollers 13a-2 (FIGS. 4 and 5 to be described later) are turned on. Apply pressure. For this reason, conveyance failure can be prevented.
As shown in FIG. 3, the reverse sensor 14 disposed immediately after the discharge upper driven roller 11b in the fourth transport path transmits the drive to the reverse roller 13 after detecting the leading edge 1a of the document 1 during the reverse switchback. Since the motor (not shown) is stopped and the motor is started after the paper discharge sensor 10 arranged in the second transport path after detecting the leading edge 1b of the document 1 after reading, it is possible to prevent the motor and the machine from rising in temperature. it can.

FIG. 4 is a schematic plan view showing a reversing roller and a reversing driven roller according to the present invention. FIG. 5 is a schematic perspective view showing the reverse driven roller. As shown in FIG. 4, the reverse roller 13 and the reverse driven roller 13a are divided.
That is, the reversing roller 13 is composed of a central reversing roller 13-1 and both end reversing rollers 13-2, and the reversing driven roller 13a is composed of a center reversing driven roller 13a-1 and both end reversing driven rollers 13a-2. Has been.
In this case, the reverse driven roller 13a is in a pressurized state only at the center reverse driven roller 13a-1, and the both end reverse driven rollers 13a-2 are released. The roller release configuration is as follows.

As shown in FIG. 5, the both-end inverted driven roller 13 a-2 is attached to a guide 17, and this guide 17 is attached to a guide lever 18. The movement of the guide lever 18 is transmitted to the solenoid plunger portion 20 via the link 19. The both-side reversing driven roller 13a-2 is pressed by the torsion spring 21.
By canceling the both-end reversing driven roller 13a-2, the applied pressure is reduced and the load applied to the torque limiter is reduced, so that the torque limiter is not acted on and is instantaneously switched to the driving direction, and the document is reversed. It is conveyed to. Accordingly, even thin paper can easily enter the nip between the reversing roller 13 and the both-end reversing driven roller 13a-2, and the restriction on the paper thickness can be eliminated for the user.

As shown in FIG. 5, since the pulling force of the entire reversing roller 13 is increased by switching the both-end reversing driven roller 13a-2 in the pressurizing direction, the motor applied to the reversing roller 13 from the middle of conveyance can be driven. Even if it is stopped, the torque limiter built in the reversing roller 13 is activated and the reversing roller 13 is rotated along with the document conveyance, so that no slip noise is generated between the roller rubber and the paper document, and noise can be prevented. .
In this way, at the time of reverse switchback, the reverse driven roller 13a that has been released is switched in the holding direction, so that the original can be conveyed without slipping and noise can be prevented.

FIG. 6 is a schematic diagram for explaining the movement of the document in the automatic document feeder of FIG. 6A shows the document 1 on the document table 2 in the single-sided mode, and FIG. 6A shows the document 1 leading edge 1a and the document 1 trailing edge 1b. FIG. 6B shows the original 1 discharged to the paper discharge unit 15, and FIG. 6B shows the front end 1a of the original 1 and the rear end 1b of the original 1.
FIG. 6C shows the document 1 leading edge 1a and document 1 trailing edge 1b in the first image plane reading in the duplex mode. As shown in FIG. 2, the document 1 passes through the first conveying path and passes through the reading unit 9, and the document 1 passes through the switching claw 12 moving to the position of A ′, and is connected between the reversing roller 13 and the reversing driven roller 13 a. The nip is being conveyed.
FIG. 6D shows the document 1 being conveyed through the nip between the reverse roller 13 and the reverse driven roller 13a after reading the first image surface in the duplex mode, as shown in FIG. In this case, the relationship between the leading edge 1a of the document 1 and the trailing edge 1b of the document 1 is as shown in FIG.
FIG. 6F shows a state in which the rear end 1b of the document 1 is fed back to the reversing sensor 14 immediately after the discharge upper driven roller 11b in the fourth transport path, as shown in FIG.

In FIG. 6G, the reverse roller 13 passes through the switching claw 12 which has passed through the reading unit 9 through the first conveyance path and moved to the position A ′, with the trailing edge 1b of the document 1 leading. And the reverse driven roller 13a are conveyed through the nip.
When the document 1 is conveyed from the state shown in FIG. 6F to the state shown in FIG. 6G, the size of the document 1 is large, so that the leading edge 1a of the document 1 comes out of the nip between the reverse roller 13 and the reverse driven roller 13a. The document 1 trailing edge 1b enters the nip at a timing that cannot be reached.
In the present invention, after the switching claw 12 returns, the reversing roller 13 reverses, and the rear end 1b of the original 1 is a post-reading roller (paper discharge roller) 11 and a post-reading driven roller (on paper discharge) for reading the second original surface. It enters the fourth transport path having a nip with the driven roller 11b, and enters the first transport path.
Thereafter, when a certain pulse has elapsed after the sensor 10 on the second transport path downstream of the image reading unit 9 detects the leading edge 1a of the document 1, the solenoid is turned on, and the leading edge 1a of the document 1 enters the nip between the reverse roller 13 and the reverse driven roller 13a. When it reaches, the reverse driven roller 13a (both ends reverse driven roller 13a-2 (FIGS. 4 and 5 described later)) is to be released.

FIG. 6I shows the state of the document 1 after reading the second document surface in the duplex mode. 6 (j) shows the state of the original discharged from the state shown in FIG. 6 (i) through the state shown in FIG. 6 (f) and the state shown in FIG. 6 (g). Indicates the state. This is to eliminate the occurrence of the page order error of the document as described above.
In FIG. 6, the document 1 shown in FIGS. 1 to 3, its leading edge 1 a, trailing edge 1 b, document table 2, pre-reading roller 7, registration sensor 8, reading unit 9, paper discharge sensor 10, 2 a post-reading roller 11 on the transport path, a post-read driven roller (paper discharge upper roller) 11a, a post-read driven roller (paper discharge upper driven roller) 11b, a switching claw 12, a reverse roller 13, a reverse driven roller 13a, a reverse sensor 14, and A paper discharge unit 15 is schematically shown.
FIG. 7 is a schematic view showing the appearance of an image forming apparatus equipped with an automatic document feeder according to the present invention. In FIG. 6, the image forming apparatus A includes an automatic document feeder 20, an image forming unit 21 for writing, developing, transferring and fixing an image, and a paper feeding unit 22 for supplying a recording medium for image transfer. .

1 is a schematic diagram showing an overall configuration of an automatic document feeder according to the present invention. FIG. 2 is a schematic view showing the movement of a document in the duplex mode of the automatic document feeder of FIG. 1. FIG. 2 is a schematic diagram illustrating the movement of a document after reading a second image surface of the automatic document feeder of FIG. 1. It is a schematic plan view which shows the inversion roller and inversion driven roller by this invention. It is a schematic perspective view which shows a reverse driven roller. FIG. 2 is a schematic diagram for explaining the movement of a document in the automatic document feeder of FIG. 1. 1 is a schematic view showing an external appearance of an image forming apparatus equipped with an automatic document feeder according to the present invention.

Explanation of symbols

A Image forming apparatus, 1 document, 1a document leading edge, 1b document trailing edge, 5 separation member, 6 first conveying roller, 9 reading unit, 10 paper discharge sensor, 11 reading roller, 13 reversing roller, 13a reversing driven roller member (Reversed driven roller), 13a-2 Both-end reversed driven roller, 14 Reverse sensor, 20 Automatic document feeder, 21 Image forming unit, 22 Paper feeding unit

Claims (6)

  An automatic document having a reverse driven roller member facing a reversing roller for separating and transporting a set original document from the top and conveying a double-sided original document, and the reversing roller has a built-in torque limiter In the conveying apparatus, when the leading edge and the trailing edge of the document overlap on the reversing roller, the pressure applied to the reverse driven roller member is released.   2. The automatic document feeder according to claim 1, wherein the release timing for releasing the reverse driven roller member is when the leading edge of the document is detected by a sensor arranged upstream of the reverse roller or after it is detected.   3. The automatic document conveying device according to claim 1, wherein the motor for driving the reverse roller is stopped from the middle of conveyance at the time of reverse switchback.   4. The automatic document feeder according to claim 1, wherein the reverse driven roller member that has been released is switched in a holding direction during the reverse switchback. 5.   An image reading apparatus for reading image information while conveying an original, wherein the automatic original conveying apparatus according to any one of claims 1 to 4 is mounted for conveying the original.   6. An image forming apparatus comprising: the image reading apparatus according to claim 5, wherein the image forming apparatus reads image information from a document and transfers an image formed by an image forming unit onto a recording medium from a sheet feeding device. apparatus.

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