JP2021181351A - Document feeder, image reader, image forming apparatus, and document conveyance method - Google Patents

Abstract

To provide a document feeder that can increase a continuous conveyance speed of a document while ensuring stackability of documents to a document discharge tray.SOLUTION: A document feeder 56 includes a plurality of conveyance rollers 66 provided in a document conveyance path L3 and a control unit that controls them. The control unit controls the operation of the plurality of conveyance rollers so that a rear end of a leading document and a front end of a trailing document overlap at a position in front of a paper discharge roller 66 g. At the same time, the control unit controls the separation/contact operation of the paper discharge roller so that another conveyance roller and the paper discharge roller do not simultaneously hold the same document.SELECTED DRAWING: Figure 2

Description

The present invention relates to a document feeder, an image reader, an image forming apparatus, and a document transport method. In particular, for example, a document can be continuously transported from a document loading tray on which a document is loaded to a document ejection tray via an image scanning position. The present invention relates to a document feeder, an image reader, an image forming apparatus, and a document transporting method.

An example of a conventional document feeder is disclosed in Patent Document 1. The document feeder of Patent Document 1 includes a document transfer path, a plurality of optical sensors arranged along the document transfer direction and receiving detection light on the detection surface to detect the presence or absence of a document on the document transfer path, a transfer roller, and the like. It is provided with a control unit that controls the document transport operation. Further, this document feeder includes an endless belt made of a transmission member arranged between the document transfer path and the optical sensor along the document transfer path, an endless belt driving means for transporting and driving the endless belt, and an endless belt. It is provided with a cleaning means for removing stains on the surface of the belt.

Japanese Unexamined Patent Publication No. 2009-96568

In such a document feeder, it is desired to increase the continuous transfer speed (and thus the continuous reading speed) of documents. However, as the transmission speed of the originals by the conveying roller is increased, the originals are ejected from the originals conveying path and are scattered on the original paper ejection tray, that is, the stacking property of the originals is deteriorated.

In order to ensure the stackability of the originals with respect to the original paper ejection tray, for example, the originals conveying speed of the paper ejection roller provided at the downstream end of the originals conveying path is slowed down only when the rear end of the originals passes. By doing so, it is conceivable to apply a brake to the document ejected to the document ejection tray. However, if the document transport speed of the paper ejection roller is lowered, this portion becomes a bottleneck, and the speeding up of the continuous document transport speed is limited.

Therefore, a main object of the present invention is to provide a novel document feeder, image reader, image forming apparatus and document transport method.

Another object of the present invention is to provide a document feeder, an image reader, an image forming apparatus, and a document transport method capable of increasing the continuous transport speed of documents while ensuring stackability of documents with respect to a document ejection tray. It is to be.

The first invention is a document feeding device capable of continuously transporting a document from a document loading tray on which a document is loaded to a document ejection tray via an image reading position, and is a plurality of transporting devices provided in a document transport path. It includes a roller and a control unit that controls the transfer operation of a document by a plurality of transfer rollers. The plurality of transport rollers include a paper discharge roller provided at the downstream end of the document transport path and set to have a slower document transport speed than the other transport rollers. In the paper discharge roller, one roller is the other roller. Includes a pair of rollers provided so that they can be detached from each other. Then, in the control unit, the rear end portion of the preceding document and the front end portion of the succeeding document are arranged on the upstream side of one of the other transport rollers, the paper discharge roller and the paper discharge roller. The document transfer operation of the plurality of transfer rollers is controlled so that they overlap each other at the position between the and. Further, the control unit controls the disengagement operation of the paper ejection rollers so that the other conveying rollers and the paper ejection rollers do not hold the same original document at the same time when the originals are conveyed by the plurality of conveying rollers.

According to the first invention, since the document transport speed of the paper ejection roller is set to a speed slower than the document transport speed of the other transport rollers, it is possible to prevent the document from popping out to the document ejection tray. In addition, the rear end of the preceding document and the front end of the succeeding document are overlapped and conveyed at a position in front of the paper ejection roller, and the paper ejection roller holds the same document at the same time as other conveying rollers. Therefore, even if the paper feed timing is shortened while ensuring the original transfer speed, the original can be appropriately conveyed. Therefore, it is possible to appropriately increase the continuous transport speed and the continuous reading speed of the originals while ensuring the stackability of the originals with respect to the original paper ejection tray.

The second invention is subordinate to the first invention. Immediately after passing through, the paper ejection roller is brought into contact with the paper ejection roller.

According to the second invention, it is possible to appropriately prevent the paper ejection roller from holding the same document at the same time as the other transport rollers.

The third invention is dependent on the first or second invention, and includes an upper transport guide provided at a position between the pre-discharge transport roller and the paper discharge roller. The upper transport guide is provided so as to extend diagonally downward toward the downstream side.

According to the third invention, the front end portion of the succeeding manuscript can be appropriately superposed on the rear end portion of the preceding manuscript.

The fourth invention is dependent on any one of the first to third inventions, and the paper ejection roller is arranged at a position shifted downward with respect to the direction of transporting the original by the paper ejection pre-delivery roller.

According to the fourth invention, the front end portion of the succeeding manuscript can be appropriately superposed on the rear end portion of the preceding manuscript.

The fifth invention is dependent on any one of the first to fourth inventions, and the paper ejection roller includes a plurality of roller pairs arranged at predetermined intervals in the document transport direction, and is at least the most upstream of the plurality of roller pairs. A pair of rollers on the side is provided so as to be detachable.

According to the fifth invention, since the originals can be stably ejected to the original paper ejection tray, the stackability of the originals with respect to the original paper ejection tray can be further improved.

The sixth invention is an image reading device including the document feeding device according to any one of the first to fifth aspects.

The seventh invention is an image forming apparatus including the image reading apparatus according to the sixth invention.

The eighth invention is a document feeding device provided with a plurality of transport rollers provided in a document transport path, capable of continuously transporting documents from a document loading tray on which documents are loaded to a document ejection tray via an image reading position. (A) Of the plurality of transport rollers, the document transport speed of the paper ejection roller provided at the downstream end of the document transport path is set to a speed slower than the document transport speed of the other transport rollers. By setting, the rear end of the preceding document and the front end of the succeeding document are the paper ejection roller and the paper ejection roller arranged on the upstream side of one of the paper ejection rollers. In the step of transporting documents by a plurality of transport rollers so that they overlap each other at the positions between them, and (b) when transporting a document by a plurality of transport rollers, the other transport rollers and the paper ejection roller simultaneously transfer the same original. This is a document transporting method including a step of separating and contacting a paper ejection roller so as not to be in a pinched state.

According to the sixth to eighth inventions, the same function and effect as those of the first invention are obtained, and the continuous transfer speed of the originals, and thus the continuous reading speed, is increased while ensuring the stacking property of the originals with respect to the original paper ejection tray. Can be raised appropriately.

According to the present invention, since the document transport speed of the paper ejection roller is set to a speed slower than the document transport speed of other transport rollers, it is possible to prevent the document from popping out to the document ejection tray. In addition, the rear end of the preceding document and the front end of the succeeding document are overlapped and conveyed at a position in front of the paper ejection roller, and the paper ejection roller holds the same document at the same time as other conveying rollers. Therefore, even if the paper feed timing is shortened while ensuring the original transfer speed, the original can be appropriately conveyed. Therefore, it is possible to appropriately increase the continuous transport speed and the continuous reading speed of the originals while ensuring the stackability of the originals with respect to the original paper ejection tray.

The above-mentioned object, other object, feature and advantage of the present invention will be further clarified from the detailed description of the examples described below with reference to the drawings.

It is sectional drawing which shows the internal structure of the image forming apparatus which comprises the image reading apparatus which has the document feeding apparatus of 1st Embodiment of this invention. It is sectional drawing which shows the internal structure of the image reading apparatus of FIG. FIG. 3 is an illustrated diagram schematically showing a portion around a paper ejection roller of the document feeder of FIG. 1. It is a schematic diagram which shows typically the document transport operation in the document feeder of FIG. 1. It is a block diagram which shows the electric structure of the image forming apparatus of FIG. It is a schematic diagram which shows an example of the memory map of the RAM shown in FIG. It is a flow diagram which shows an example of the document transfer process executed by the CPU shown in FIG. It is sectional drawing which shows the internal structure of the image reading apparatus which has the document feeding apparatus of 2nd Embodiment of this invention. FIG. 5 is an illustrated diagram schematically showing a document transport operation in the document feeder of FIG. 8. It is a schematic diagram which shows the modification of the document feed device schematically. It is a schematic diagram which shows the other modification of the document feeder schematically.

[First Example]
With reference to FIG. 1, the document feeder 56, which is an embodiment of the present invention, transmits a document loaded on a document placing tray 60 via image reading positions P1 and P2 (see FIG. 2) to eject the document. An automatic document feeder (ADF: Auto Document Feeder) capable of automatically continuously transporting sheets one by one to the tray 62, which is provided in the image reading device 14.

As will be described in detail later, in this first embodiment, the image reading device 14 includes a first image reading unit 50 and a second image reading unit 54, and both sides of the document conveyed by the document feeding device 56. Can be read at the same time. Further, the image reading device 14 having the document feeding device 56 is applied to the image forming device 10 that forms an image on paper by an electrophotographic method.

First, the basic configuration of the image forming apparatus 10 will be schematically described. In this first embodiment, the image forming apparatus 10 is a multifunction device (MFP: Multifunction Peripheral) having a copying function, a printer function, a scanner function, a facsimile function, and the like.

As shown in FIG. 1, the image forming apparatus 10 includes an image forming apparatus main body 12 and an image reading apparatus 14 arranged above the image forming apparatus main body 12.

The image forming apparatus main body 12 includes a control unit 16 including a CPU 80 (see FIG. 5) and the like, an image forming unit 18, and the like. The control unit 16 transmits a control signal to each part of the image forming apparatus 10 including the document feeding apparatus 56 and the image reading apparatus 14 in response to an input operation to the operation panel 88 (see FIG. 5), and causes the image forming apparatus. 10 is made to perform various operations. That is, the control unit 16 is also a control unit of the document feeding device 56 and the image reading device 14.

The image forming unit 18 includes an exposure unit 20, a developer 22, a photoconductor drum 24, a cleaner unit 26, a charger 28, an intermediate transfer belt unit 30, a transfer roller 32, a fixing unit 34, and the like, and is provided from a paper feed tray 36 and the like. An image is formed on the conveyed paper, and the image-formed paper is ejected to the output tray 38. As the image data for forming an image on the paper, image data read by the first image reading unit 50 and the second image reading unit 54, which will be described later, image data transmitted from an external computer, or the like is used.

The image data handled by the image forming apparatus 10 corresponds to four color images of black (K), cyan (C), magenta (M), and yellow (Y). For this reason, the developer 22, the photoconductor drum 24, the cleaner unit 26, and the charger 28 are each provided with four so as to form four types of latent images corresponding to each color, whereby four image stations are provided. It is composed.

Further, in the housing of the image forming apparatus main body 12, a first paper transport path for sending paper from the paper feed tray 36 or the like to the paper output tray 38 via the resist roller 40, the transfer roller 32, and the fixing unit 34. L1 is formed. Further, when double-sided printing is performed on paper, the paper after single-sided printing is completed and has passed through the fixing unit 34 is returned to the first paper transport path L1 on the upstream side of the transfer roller 32 in the paper transport direction. The second paper transport path L2 is formed. A plurality of transport rollers for additionally applying a propulsive force to the paper are appropriately provided in the first paper transport path L1 and the second paper transport path L2.

With reference to FIG. 1 and FIG. 2, the image reading device 14 includes a first housing 52 provided with a first image reading unit 50, and a second housing provided with a second image reading unit 54 and a document feeder 56. It is equipped with 58. The second housing 58 is attached to the upper surface of the first housing 52 so as to be openable and closable via a hinge, and is also used as a document holding cover. Further, on the front side of the first housing 52, an operation panel 88 for receiving an input operation such as a print instruction by the user is provided. The operation panel 88 is appropriately provided with a display with a touch panel, operation buttons, and the like.

The first housing 52 has a document mounting table 52a formed of a transparent material on the upper surface, and a first image reading unit 50 for reading a surface image of the document is provided in the first housing 52. The first image reading unit 50 includes a light source, a plurality of mirrors, an imaging lens, a line sensor, and the like. The light source, a plurality of mirrors, and the like constitute a scanning unit. The first image reading unit 50 exposes the surface of the document with a light source, and guides the reflected light reflected from the surface of the document to the imaging lens by a plurality of mirrors. Then, the reflected light is imaged on the light receiving element of the line sensor by the imaging lens. The line sensor detects the luminance and chromaticity of the reflected light imaged on the light receiving element, and generates image data based on the image on the surface of the document. As the line sensor, a CCD (Charge Coupled Device), a CMOS image sensor, or the like may be used. Further, a CIS (Contact Image Sensor) that integrates a light source, an image pickup lens, a line sensor, and the like may be used.

Such a first image reading unit 50 corresponds to a fixed reading that reads an image of a document placed on a document mounting table 52a and a scanning reading that reads an image of a document conveyed by the document feeding device 56. There is. That is, in the case of fixed reading, a scanning unit such as a light source and a plurality of mirrors reciprocates below the document mounting table 52a in the sub-scanning direction to read an image on the document mounting table 52a side of the document. On the other hand, in the case of scanning, the scanning unit stands by below the first image reading position P1 which is the home position. Then, the first image reading unit 50 reads the image on the front surface side (first image reading unit 50 side) of the document when the document conveyed by the document feeding device 56 passes through the first image reading position P1.

On the other hand, in the second housing 58, a second image reading unit 54 for reading an image on the back surface side of the document is provided. Like the first image reading unit 50, the second image reading unit 54 includes a light source, a plurality of mirrors, an imaging lens, a line sensor, and the like, and these are arranged in the second housing 58 in a unitized state. Will be done. The second image reading unit 54 corresponds to scanning for reading an image of a document conveyed by the document feeding device 56. That is, when the user requests double-sided scanning of the original, the second image reading unit 54 receives the back side of the original when the original conveyed by the document feeder 56 passes through the second image reading position P2. The image of the second image reading unit 54 side) is read.

A paper feed port 58a is formed in the upper part of the second housing 58, and a document loading tray 60 is provided so as to extend diagonally to the upper right from the paper feed port 58a. A paper ejection port 58b is formed in the lower portion of the second housing 58, and a document ejection tray 62 is provided so as to extend diagonally to the upper right from the paper ejection port 58b.

As described above, the document feeder 56 loads the documents loaded on the document loading tray 60 into the first image reading position P1 of the first image reading unit 50 and the second image reading position P2 of the second image reading unit 54. It is a device capable of continuously transporting one sheet at a time to the document ejection tray 62 after passing through the above.

Hereinafter, the configuration of the document feeder 56 will be specifically described with reference to FIGS. 2 and 3. Unless otherwise specified, the term "upstream" or "downstream" in the present invention means "upstream" or "downstream" in the document transport direction.

As shown in FIG. 2, the document feeder 56 is provided on the outer peripheral surface of the second image reading unit 54 from the paper feed port 58a to the paper ejection port 58b in addition to the document loading tray 60 and the document ejection tray 62 described above. A document transport path L3 extending in a U shape along the line is provided. Further, the document feeder 56 includes a pickup roller 64 for feeding the documents loaded on the document loading tray 60 one by one into the document transport path L3, and a plurality of transfer rollers for transporting the documents fed to the document transfer path L3. 66 is provided.

In this first embodiment, seven transport rollers (66a, 66b, 66c, 66d, 66e, 66f, 66g in order from the upstream side) are provided as the plurality of transport rollers 66. The plurality of transport rollers 66 include a paper feed roller 66a provided at the upstream end of the document transport path L3, a resist roller 66d provided on the upstream side of the first image reading position P1 to adjust the paper feed timing, and the like. (2) Includes a paper ejection front transport roller 66f provided on the downstream side of the image reading position P2 and one upstream side of the paper ejection roller 66g, a paper ejection roller 66g provided on the downstream end of the document transport path L3, and the like. Is done.

Further, a document position detection sensor 68 for detecting the position or presence / absence of the document transported on the document transport path L3 is provided at a position near the upstream side of the paper ejection transport roller 66f. Further, in addition to the document position detection sensor 68, the document transfer path L3 is appropriately provided with a document position detection sensor 70 for detecting the position or presence / absence of the document transported on the document transfer path L3.

In this first embodiment, a reflection type optical sensor is used as the document position detection sensors 68 and 70. The control unit 16 determines the presence or absence of a document according to the output from the document position detection sensors 68 and 70 (whether or not the reflected light from the document is detected). Further, the control unit 16 determines that the tip of the document has reached the detection position of the sensor when the state without the document (off state) is switched to the state with the document (on state), and the control unit 16 switches from the on state to the off state. When switching, it is determined that the rear end of the document has reached the detection position of the sensor. However, as the document position detection sensors 68 and 70, other sensors such as a transmission type optical sensor and a contact type sensor can also be used.

Further, on the lower side of the document placing tray 60, there is a document presence / absence detection sensor 72 for detecting the presence / absence of a document placed on the document placing tray 60, and a document placed on the document placing tray 60. Document size detection sensors 74a and 74b for detecting the size are provided. For example, the document presence / absence detection sensor 72 is provided at the upstream end of the document loading tray 60. Further, for example, one document size detection sensor 74a is arranged at a position corresponding to the downstream end portion of an A4 size document, and the other document size detection sensor 74b corresponds to the downstream end portion of an A3 size document. It is placed in the position where it is. In this first embodiment, a reflection type optical sensor is used as the document presence / absence detection sensor 72 and the document size detection sensors 74a and 74b. However, as the document presence / absence detection sensor 72 and the document size detection sensors 74a and 74b, other sensors such as a contact type sensor can also be used.

In such a document feeder 56, the paper feed timing (document spacing) by the pickup roller 64 and the resist roller 66d, the document transfer speed (peripheral speed) of each transfer roller 66, and the like are determined according to the scanning resolution, the document size, and the like. Document transport conditions are determined. Then, based on the control signal from the control unit 16, the roller drive unit 90 (see FIG. 5) for driving each of the rollers 64, 66 is driven and controlled.

Here, the continuous transfer speed of documents by the document feeder 56 (and the continuous reading speed by the image reading device 14) can be increased, that is, the total time required for continuous transfer (continuous reading) of a plurality of documents can be shortened. desired. However, simply increasing the document transport speed by the plurality of transport rollers 66 causes a problem that the stackability of the documents with respect to the document ejection tray 62 deteriorates.

Therefore, in this first embodiment, the document transport speed of the paper ejection roller 66g is set to a speed slower than the document transport speed of the other transport rollers 66a to 66f, so that the paper ejection port 58b is connected to the document ejection tray 62. The momentum of the ejected originals was reduced to ensure the stackability of the originals with respect to the original paper ejection tray 62. The document transport speed of the paper ejection roller 66g is preferably set to a size of 1/4 or more and 1/2 or less of the document transport speed of the other transport rollers 66a to 66f, and 3 minutes in this first embodiment. It is set to a size of about 1.

Further, in the first embodiment, in order to increase the continuous transport speed (continuous reading speed) of the originals while ensuring the stackability of the originals with respect to the original paper ejection tray 62, when the originals are continuously conveyed, the pre-paper ejection transfer rollers are used. At a position between the 66f and the paper ejection roller 66g (that is, a position downstream of the paper ejection roller 66f and upstream of the paper ejection roller 66g), the front end of the succeeding document is behind the preceding document. The document transfer operation (rotational operation) of the plurality of transfer rollers 66 is controlled so that the rear end of the preceding document and the front end of the succeeding document overlap each other by overtaking the edges. That is, by stacking and transporting a part of the originals at a position in front of the paper ejection roller 66 g, it is possible to shorten the paper feed timing (spacing between originals) while ensuring the original transport speed, and the continuous transfer speed of the originals is increased. I made it possible to raise it.

When stacking the edges of the original documents, it is preferable to stack the edges of the subsequent documents so that the front edges of the documents are placed on the rear edges of the preceding documents. This is because the preceding original is loaded on the original paper ejection tray 62 on the lower side.

Further, in the first embodiment, even if the rear end portion of the preceding original document and the front end portion of the succeeding original document are overlapped and conveyed, the original document can be appropriately conveyed without causing a problem such as jamming of the original document. The following configuration was adopted.

As shown in FIG. 3, the paper ejection roller 66g of the first embodiment is composed of a roller pair having a drive roller 66g1 arranged on the lower side and a driven roller 66g2 arranged on the upper side. Further, the driven roller 66g2 is provided so as to be vertically detachable from the driving roller 66g1 by a detaching mechanism (not shown). That is, the paper ejection roller 66g is in a separated state in which the driven roller 66g2 is separated from the driving roller 66g1 and in a contact state in which the driven roller 66g2 is in contact with the driving roller 66g1 at a predetermined pressure (that is, the original is sandwiched and conveyed). It is possible to displace it.

When the original is conveyed, the control unit 16 controls the detaching operation of the paper ejection roller 66g so that the other conveying rollers 66a to 66f and the paper ejection roller 66g do not simultaneously hold the same original document. That is, if one transfer roller 66a to 66f and the paper ejection roller 66g, which have significantly different document transfer speeds (peripheral speeds), simultaneously transfer one document, jam may occur. Therefore, the other transfer rollers When the document conveyed by 66a to 66f passes through the paper ejection roller 66g, the paper ejection roller 66g is separated. On the other hand, when the originals are not conveyed by the other conveying rollers 66a to 66f, the paper ejection rollers 66g are brought into contact with each other, and the originals are decelerated by the paper ejection rollers 66g to the original paper ejection tray 62. Discharge. Then, when the next document is conveyed by the other transfer rollers 66a to 66f, the paper ejection rollers 66 g are separated from each other, and the document transfer operation is repeated thereafter. As a result, the occurrence of jam can be appropriately prevented.

Furthermore, in the first embodiment, the front end of the succeeding manuscript is appropriately overlapped so as to be placed on the rear end of the preceding manuscript without colliding with the rear end of the preceding manuscript. In order to match, the following configuration is adopted. That is, in the first embodiment, the upper transport guide 76 extending diagonally downward toward the downstream side is provided at a position between the paper ejection roller 66f and the paper ejection roller 66g. The upper transport guide 76 pushes down the rear end portion of the preceding document so that the front end portion of the succeeding document is placed on the rear end portion of the preceding document. Further, the paper ejection roller 66g is arranged at a position shifted downward with respect to the document transporting direction Df by the paper ejection pre-delivery roller 66f. By shifting the paper ejection roller 66g downward, the rear end portion of the preceding document moves below the front edge portion of the succeeding document after passing through the paper ejection pre-delivery roller 66f, so that the front end portion of the succeeding document is moved. The section will be placed on the rear edge of the preceding manuscript.

Subsequently, with reference to FIG. 4, an example of the continuous transfer operation of the document in the document feeder 56 as described above will be specifically described. When starting continuous transfer of documents, first, depending on the scanning resolution, the document size, etc., the rear end of the preceding document and the front end of the succeeding document are the pre-paper ejection transfer roller 66f and the paper ejection roller 66g. Document transfer conditions such as paper feed timing and document transfer speed are determined so that they overlap each other at the position between and. Then, the transfer roller 66 and the like are driven under the determined document transfer conditions, so that the documents are continuously conveyed.

As shown in FIG. 4A, after the continuous transfer of the original is started, the tip of the first original G1 passes through the first image reading position P1 and the second image reading position P2 and immediately before the paper ejection roller 66g. When the position P4 (for example, a position at a distance of 0.5 cm or more and 2.0 cm or less from the nip region of the paper ejection roller 66g) is reached, the driven roller 66g2 is moved upward and the paper ejection roller 66g. Is put into a separated state. The reason why the paper ejection roller 66g is separated is to prevent the paper ejection roller 66f and the like from being in a state where the same original document is sandwiched (conveyed) at the same time.

It should be noted that the arrival of the tip of the document at the immediately preceding position P4 is determined by, for example, whether or not the first predetermined time has elapsed from the time when the tip of the document reaches the detection position P3 of the document position detection sensor 68. The first predetermined time [s] is the value obtained by dividing the transport path length [m] from the detection position P3 to the immediately preceding position P4 by the document transport speed (peripheral speed) [m / s] of the pre-paper ejection transport roller 66f. Set.

After that, as shown in FIG. 4 (B), when the first original document G1 is conveyed by the pre-paper ejection transfer roller 66f, the paper ejection roller 66g is left in a separated state. Then, as shown in FIG. 4C, the rear end of the first document G1 is at a position P5 immediately after the pre-paper ejection transfer roller 66f (for example, 0.1 cm or more downstream from the nip region of the pre-emission paper transfer roller 66f). When it reaches a position (with a space of 1.0 cm or less), that is, when it comes out of the paper ejection front transport roller 66f, the driven roller 66g2 is moved downward and the paper ejection roller 66g is brought into contact with the paper ejection roller 66g. As a result, the first document G1 is brought into a state of being conveyed by the paper ejection roller 66 g and is decelerated. Further, when the rear end of the first document G1 passes through the paper ejection front transport roller 66f, the upper transport guide 76 pushes down the first document G1 and the paper ejection roller 66g is arranged at a position shifted downward. Therefore, the rear end portion of the first document G1 moves below the transport direction Df by the pre-paper ejection transport roller 66f.

The fact that the rear end of the document reaches the position P5 immediately after the document is determined by, for example, whether or not a second predetermined time has elapsed from the time when the tip of the document reaches the detection position P3 of the document position detection sensor 68. The second predetermined time [s] is set to a value obtained by dividing the transport path length [m] from the detection position P3 to the immediately after position P5 by the document transport speed [m / s] of the pre-paper ejection transport roller 66f.

After that, as shown in FIG. 4D, while the preceding first document G1 is being conveyed by the paper ejection roller 66g, the front end of the succeeding second document G2 takes the rear end of the preceding first document G1. Overtaking, the rear end portion of the preceding first manuscript G1 and the front end portion of the succeeding second manuscript G2 overlap each other. At this time, since the rear end portion of the first document G1 moves below the transport direction Df by the pre-discharge transfer roller 66f, the front end of the second document G2 conveyed by the pre-discharge transfer roller 66f. The portions are appropriately superimposed on the rear end portion of the first document G1.

Then, as shown in FIG. 4E, when the front end of the subsequent second document G2 reaches the immediately preceding position P4, the driven roller 66g2 is moved upward and the paper ejection roller 66g is separated. After that, as shown in FIG. 4F, the overlapped portion of the first document G1 and the second document G2 passes through the separated paper ejection roller 66 g, and the first document G1 inertially moves. It is ejected to the original paper ejection tray 62 in a decelerated state. Even if the first original document G1 is not ejected by inertial movement and remains in the paper ejection roller 66g portion, the subsequent second original document G2 is simultaneously overlapped and conveyed when it is conveyed by the paper ejection roller 66g. The document G1 is appropriately ejected to the document ejection tray 62.

After that, as shown in FIG. 4 (G), when the rear end of the second document G2 reaches the position P5 immediately after the pre-paper ejection transfer roller 66f, the paper ejection roller 66g is brought into contact with the second document. G2 is decelerated. Then, the same continuous transfer operation is repeated for the preceding second manuscript and the succeeding third manuscript, and also when there is a succeeding manuscript.

By performing the document transfer operation as described above, the paper feed timing (document spacing) can be shortened while ensuring the document transfer speed, so the continuous document transfer speed (continuous reading speed) should be increased. Can be done.

FIG. 5 is a block diagram showing an example of the electrical configuration of the image forming apparatus 10. However, some components that are not directly related to the present invention are omitted.

As shown in FIG. 5, the image forming apparatus 10 includes a control unit 16 including a CPU 80, a RAM 82, an HDD 84, and the like. The image forming unit 18, the first image reading unit 50, the second image reading unit 54, the operation panel 88, and the like described above are connected to the CPU 80 via the bus 86. Further, the CPU 80 has a roller drive unit 90 of the document feeder 56, a detachment mechanism drive unit 92, and an optical sensor (manuscript position detection sensors 68, 70, document presence / absence detection sensor 72, and document size detection) via the bus 86. Sensors 74a, 74b) and the like are connected.

The CPU 80 controls the overall control of the image forming apparatus 10 according to the program stored in the HDD 84. Further, the CPU 80 executes the document transfer process of the first embodiment. The RAM 82 is used as a working area and a buffer area of the CPU 80. The HDD 84 appropriately stores a control program for the CPU 80 to control the operation of each part of the image forming apparatus 10, necessary data, and the like. However, other non-volatile memory such as SSD, flash memory, EEPROM may be used instead of the HDD or together with the HDD. Since the image forming unit 18, the first image reading unit 50, and the second image reading unit 54 are as described above, duplicate description will be omitted.

The operation panel 88 includes a display with a touch panel, operation buttons, and the like. The display is a general-purpose monitor such as an LCD, and is connected to the CPU 80 via a display control circuit (not shown). The display control circuit includes GPU, VRAM and the like. Under the instruction of the CPU 80, the GPU uses the image generation data stored in the RAM 82 to generate display image data for displaying various screens on the display in the VRAM, and outputs the generated display image data to the display. .. The touch panel detects a touch operation within the effective touch range and outputs touch coordinate data indicating the position of the touch operation to the CPU 80. The operation buttons are hardware keys and include various keys or buttons such as a home button, a power saving key and a power button.

The roller drive unit 90 includes a motor for driving the pickup roller 64 and a motor for driving a plurality of transfer rollers 66. As the motor, a general-purpose rotary motor is used. The roller driving unit 90 applies a rotational driving force to the pickup roller 64 and each transport roller 66 according to the instructions of the CPU 80. The disengagement mechanism driving unit 92 is a motor for driving the disengagement mechanism of the paper ejection roller 66g, and disengages the paper ejection roller 66g, that is, moves the driven roller 66g2 up and down according to the instruction of the CPU 80. As described above, the optical sensor such as the document position detection sensor 68 outputs a signal according to the presence or absence of the document to the CPU 80, and the CPU 80 determines whether or not the document exists at each detection position according to the output of the optical sensor. do.

The operation of the image forming apparatus 10 including the document feeding apparatus 56 and the image reading apparatus 14 as described above is realized by the CPU 80 executing the control program stored in the RAM 82.

FIG. 6 is an illustrated diagram showing an example of the memory map 200 of the RAM 82. As shown in FIG. 6, the RAM 82 includes a program storage area 202 and a data storage area 204. The control program of the image forming apparatus 10 is stored in the program storage area 202 of the RAM 82. However, since the image forming apparatus 10 includes the document feeding device 56 and the image reading device 14, the control program stored in the program storage area 202 includes the control program of the document feeding device 56 and the image reading device 14. For example, the document detection program 202a, the document transfer program 202b, the image reading program 202c, and the image forming program 202d are stored in the program storage area 202.

The document detection program 202a is a program for acquiring the output of an optical sensor such as the document position detection sensor 68 and detecting whether or not a document exists at each detection position. The document detection program 202a includes a program for detecting the presence / absence of a document on the document mounting tray 60 based on the output from the document presence / absence detection sensor 72, and the size of the document based on the output from the document size detection sensors 74a and 74b. A program for detecting the position of the document, a program for detecting the position of the document based on the output from the document position detection sensors 68, 70, and the like are included.

The document transport program 202b controls the roller drive unit 90 and the disconnection mechanism drive unit 92 of the document feeder 56 to eject the documents loaded on the document loading tray 60 via the image reading positions P1 and P2. This is a program for automatically continuously transporting sheets one by one to the paper tray 62.

The image reading program 202c is a program for controlling the first image reading unit 50 and the second image reading unit 54 to read the image of the original and output the image signal (scanned image data) corresponding to the read image. be.

The image forming program 202d is a program for controlling the image forming unit 18 to print a multicolored or monochromatic printed image on paper according to the printed image when copying or printing is executed.

Although not shown, the program storage area 202 also stores other programs for selecting and executing various functions of the image forming apparatus 10.

Further, the document flag 204a, the document transfer data 204b, the print data 204c, and the like are stored in the data storage area 204 of the RAM 82.

The document flag 204a is a flag for determining whether or not a document exists at each detection position of an optical sensor such as the document position detection sensor 68. The document flag 204a is provided in association with each detection position and is turned on (1 is set) when the document is present at the corresponding detection position and turned off when the document is not present at each detection position. (0 is set).

The document transport data 204b is data such as the paper feed timing by the pickup roller 64 and the resist roller 66d, and the peripheral speed of each transport roller 66, which are preset according to the reading resolution, the document size, and the like.

The print data 204c is image data read by the first image reading unit 50 and the second image reading unit 54, and image data received from an external device.

Although not shown, the data storage area 204 is provided with a timer (counter) and a register necessary for executing the control program, and other data is stored.

FIG. 7 is a flow chart showing an example of a document transfer process executed by the CPU 80. This document transport process is started when the document is placed on the document loading tray 60 by the user and the copy or scan start button is operated.

As shown in FIG. 7, when the document transport process is started, the CPU 80 acquires the outputs of the document size detection sensors 74a and 74b in step S1 to detect the size of the document placed on the document mounting tray 60. do. As for the reading resolution, a preset default value is used unless otherwise specified by the user.

In the next step S3, the document transport conditions are determined based on the size and reading resolution of the document acquired in step S1. Then, in the following step S5, the transfer of the original document is started. That is, the CPU 80 determines the paper feed timing by the pickup roller 64 and the resist roller 66d, the peripheral speed of each transfer roller 66, and the like based on the size of the document, and the roller drive unit based on the determined document transfer conditions. It controls 90 and the disconnection mechanism drive unit 92.

In the following step S7, it is determined whether or not the tip of the original has reached the position P4 immediately before the paper ejection roller 66 g. For example, it is determined whether or not the tip of the document has reached the immediately preceding position P4 based on whether or not the first predetermined time has elapsed from the time when the tip of the document reaches the detection position P3 of the document position detection sensor 68. If "NO" in step S7, the process returns to step S7. On the other hand, if "YES" in step S7, that is, when the tip of the document reaches the immediately preceding position P4, the process proceeds to step S9.

In step S9, the paper ejection roller 66 g is separated. That is, the CPU 80 controls the disengagement mechanism driving unit 92 to move the driven roller 66g2 upward to put the paper ejection roller 66g in a separated state. As a result, it is possible to prevent the paper ejection roller 66f and the like and the paper ejection roller 66g from simultaneously sandwiching (conveying) the same original document.

In the following step S11, it is determined whether or not the rear end of the document has reached the position P5 immediately after the pre-paper ejection transport roller 66f. For example, it is determined whether or not the rear end of the document has reached the immediately preceding position P5 based on whether or not the second predetermined time has elapsed from the time when the rear edge of the document reaches the detection position P3 of the document position detection sensor 68. If "NO" in step S11, the process returns to step S11. On the other hand, if "YES" in step S11, that is, when the rear end of the document reaches the position P5 immediately after, the process proceeds to step S13.

In step S13, the paper ejection roller 66 g is brought into contact with each other. That is, the CPU 80 controls the disengagement mechanism driving unit 92 to move the driven roller 66g2 downward to bring the paper ejection roller 66g into a contact state. As a result, the original is conveyed by the paper ejection roller 66 g and is decelerated.

In the following step S15, it is determined whether or not there is a subsequent manuscript. For example, it may be determined whether or not there is a subsequent document based on the outputs from the document presence / absence detection sensor 72 and the document position detection sensor 70. If "YES" in step S15, that is, if there is a subsequent manuscript, the process returns to step S7. On the other hand, if it is "NO" in step S15, that is, if there is no subsequent document, this document transfer process is terminated.

As described above, according to the first embodiment, the document transport speed of the paper ejection roller 66g is set to a speed slower than the document transport speed of the other transport rollers 66a to 66f, so that the document is a document ejection tray 62. It is possible to prevent it from popping out. Further, the rear end portion of the preceding document and the front end portion of the succeeding document are overlapped and conveyed at a position in front of the paper ejection roller 66g, and the paper ejection roller 66g is transferred by the paper ejection roller 66f (another conveying roller). ) At the same time, the same document is not pinched, so the paper feed timing can be shortened while ensuring the document transport speed. Therefore, it is possible to appropriately increase the continuous transport speed and the continuous reading speed of the originals while ensuring the stackability of the originals with respect to the original paper ejection tray 62.

[Second Example]
Next, the document feeder 56, which is the second embodiment of the present invention, will be described with reference to FIGS. 8 and 9. In this second embodiment, the configuration of the paper ejection roller is different from that of the first embodiment described above. Since the other parts are the same, the description overlapping with the first embodiment described above will be omitted or simplified.

As shown in FIG. 8, in the second embodiment, the paper ejection roller includes a plurality of roller pairs arranged at predetermined intervals in the document transport direction. Specifically, in this second embodiment, nine transfer rollers (66a, 66b, 66c, 66d, 66e, 66f, 66g, 66h, 66i in order from the upstream side) are provided as the plurality of transfer rollers 66. Of these plurality of transport rollers 66, the three transport rollers (66 g, 66h, 66i) provided at the downstream end of the document transport path L3 have a slower document transport speed than the other transport rollers 66a to 66f. Used as a set paper ejection roller. That is, in this second embodiment, as the paper ejection rollers, a first paper ejection roller 66g, a second paper ejection roller 66h, and a third paper ejection roller 66i arranged at predetermined intervals in the document transport direction are provided.

Each of the first paper ejection roller 66g, the second paper ejection roller 66h, and the third paper ejection roller 66i is composed of a roller pair having a drive roller arranged on the lower side and a driven roller arranged on the upper side. Further, each of the driven rollers is provided so as to be vertically detachable from each driving roller by a detaching mechanism (not shown). That is, in each of the first paper ejection roller 66g, the second paper ejection roller 66h, and the third paper ejection roller 66i, the driven roller is separated from the drive roller and the driven roller has a predetermined pressure with respect to the drive roller. It can be displaced to the contact state where it contacts with. Further, each of the first paper ejection roller 66g, the second paper ejection roller 66h, and the third paper ejection roller 66i is displaced downward with respect to the document transporting direction Df (see FIG. 3) by the pre-paper ejection transport roller 66f. It is placed in the same position. Further, at a position between the pre-paper ejection transport roller 66f and the first paper ejection roller 66g, an upper transport guide 76 extending diagonally downward toward the downstream side is provided.

Then, at the time of document transport, the control unit 16 (CPU80) controls the paper ejection rollers 66g to 66i so that the other transport rollers 66a to 66f and the paper ejection rollers 66g to 66i do not simultaneously hold the same original document. The disconnection operation is controlled.

Subsequently, with reference to FIG. 9, an example of the continuous transfer operation of the document in the document feeder 56 of the second embodiment will be specifically described. When starting continuous transfer of documents, document transfer conditions such as paper feed timing and document transfer speed are determined, and the transfer rollers 66 and the like are driven under the determined document transfer conditions to continuously convey the documents. ..

First, as shown in FIG. 9A, when the tip of the first document G1 passes through the first image reading position P1 and the second image reading position P2 and reaches the position P4 immediately before the first paper ejection roller 66g. In addition, the driven roller 66g2 of the first paper ejection roller 66g is moved upward, and the first paper ejection roller 66g is put into a separated state. As a result, it is possible to avoid a state in which the pre-discharge transport roller 66f and the like and the first paper discharge roller 66 g simultaneously hold (convey) the same original. Further, as shown in FIG. 9B, when the tip of the first document G1 reaches the position P6 immediately before the second paper ejection roller 66h, the driven roller 66h2 of the second paper ejection roller 66h is moved upward. The second paper ejection roller 66h is separated. As a result, it is possible to avoid a state in which the pre-paper ejection transport roller 66f and the like and the second paper ejection roller 66h simultaneously hold the same original. After that, when the first document G1 is conveyed by the pre-paper ejection transfer roller 66f, the first paper ejection roller 66g and the second paper ejection roller 66h are left in a separated state.

Next, as shown in FIG. 9C, when the rear end of the first document G1 reaches the position P5 immediately after the paper ejection front transfer roller 66f, the driven roller 66g2 and the driven roller 66h2 are moved downward. The first paper ejection roller 66g and the second paper ejection roller 66h are brought into contact with each other. As a result, the first document G1 is brought into a state of being conveyed by the first paper ejection roller 66g and the second paper ejection roller 66h, and is decelerated.

After that, as shown in FIG. 9D, while the preceding first manuscript G1 is being conveyed by the first paper ejection roller 66g and the second paper ejection roller 66h, the front end of the succeeding second manuscript G2 precedes. Overtaking the rear end of the first manuscript G1 and overlapping the rear end of the preceding first manuscript G1 and the front end of the succeeding second manuscript G2.

Subsequently, as shown in FIG. 9E, when the front end of the subsequent second document G2 reaches the immediately preceding position P4, the driven roller 66g2 is moved upward and the first paper ejection roller 66g is in a separated state. Will be done. After that, as shown in FIG. 9 (F), the portion where the first document G1 and the second document G2 overlap each other passes through the separated first paper ejection roller 66 g, but the first document G1 is the second. By being conveyed by the paper ejection roller 66h and the third paper ejection roller 66i, it is stably conveyed.

After that, as shown in FIG. 9 (G), when the rear end of the second document G2 reaches the position P5 immediately after the paper ejection front transport roller 66f, the first paper ejection roller 66g and the second paper ejection roller 66h The second document G2 is decelerated in the contact state. Then, as shown in FIG. 9H, the same continuous transfer operation is repeated for the preceding second document and the succeeding third document. Further, since the first original document G1 (the same applies to the subsequent original documents) is ejected to the original paper ejection tray 62 while being conveyed by the third paper ejection roller 66i, it is stably conveyed and ejected.

In this second embodiment as well, as in the first embodiment, the continuous transport speed of the originals, and thus the continuous reading speed, can be appropriately increased while ensuring the stacking property of the originals with respect to the original paper ejection tray 62. ..

Further, according to the second embodiment, since the originals can be stably ejected to the original paper ejection tray 62, the stackability of the originals with respect to the original paper ejection tray 62 can be further improved.

In the second embodiment described above, the paper ejection roller is configured by three roller pairs, but the paper ejection roller may be configured by two roller pairs. Further, when a plurality of roller pairs are provided as the paper ejection rollers, the paper ejection rollers may be configured by four or more roller pairs, but from the viewpoint of increasing the continuous transport speed of the original, two or three rollers. It is preferable to configure the paper ejection roller by a pair. Further, if it is possible to avoid a state in which the other transport rollers and each paper ejection roller simultaneously hold the same document during document transport, at least the most upstream roller pair among the plurality of roller pairs can be separated from each other. It suffices if it is provided in.

Further, in each of the above-described embodiments, the upper transport guide 76 is provided and the paper ejection roller 66 g is ejected as a configuration for appropriately superimposing the front end portion of the succeeding document on the rear end portion of the preceding document. Although the originals are arranged at a position shifted below the original transport direction Df by the front transfer roller 66f, the following configurations can be adopted in addition to or in place of these configurations. ..

For example, as shown in FIG. 10, a lower transport guide 94 extending diagonally upward toward the downstream side may be provided at a position near the downstream side of the paper ejection front transport roller 66f. As a result, the rear end portion of the preceding document moves downward after passing through the lower transport guide 94, and the front end portion of the succeeding document is lifted by the lower transport guide 94, so that the front end portion of the succeeding document is preceded. It can be properly overlaid on the rear edge of the original.

Further, for example, as shown in FIG. 11, when the paper ejection roller is composed of a plurality of roller pairs, the paper ejection roller is located on the most upstream side of the paper ejection rollers with respect to the document conveying direction Df by the paper ejection front transport roller 66f. It is also possible to arrange each roller so that the upward tilt angle with respect to the horizontal direction is larger in the document transport direction (Dg) by the arranged paper ejection roller (first paper ejection roller 66 g). This also allows the front end of the succeeding document to be appropriately overlaid on the rear edge of the preceding document.

Further, in each of the above-described embodiments, in the paper ejection roller, the lower roller is a drive roller and the upper roller is a driven roller, but the lower roller is a driven roller and the upper roller is a drive roller. You can also do it. In this case, the driven roller on the lower side may be displaced in the vertical direction.

The specific configurations of the image forming apparatus mentioned in the present specification are merely examples, and can be appropriately changed according to the specifications of the actual product. That is, the image forming apparatus to which the document feeding apparatus according to the present invention is applied does not necessarily have to be a multifunction device, and any of the above other functions can be arbitrarily adopted as long as it has at least an image reading function. .. Further, the image forming apparatus may be a monochrome machine that forms a monochromatic image on a recording medium, and the image forming unit may be configured by an inkjet printer or the like instead of a laser printer.

Further, the document feeder according to the present invention can also be applied to a single image scanning device (scanner). Further, the image reading device to which the document feeding device is applied does not necessarily have to include two image reading units, but includes at least one image reading unit (one of the first image reading unit and the second image reading unit). Just do it.

In addition, the specific numerical values and member shapes mentioned above are merely examples, and can be appropriately changed as needed, such as product specifications.

10 ... Image forming device 12 ... Image forming device main body 14 ... Image reading device 16 ... Control unit 18 ... Image forming unit 50 ... First image reading unit 54 ... Second image reading unit 56 ... Document feeding device 60 ... Document loading tray 62 ... Original paper ejection tray 66 ... Conveying roller 66f ... Pre-discharging transport roller (other transport rollers)
66g, 66h, 66i ... Paper ejection roller 68 ... Document position detection sensor 76 ... Upper transfer guide 80 ... CPU

Claims (8)

A document feeder capable of continuously transporting originals from the original loading tray on which the originals are loaded to the original paper ejection tray via the image reading position.
It is provided with a plurality of transport rollers provided in the document transport path and a control unit for controlling the transport operation of the document by the plurality of transport rollers.
The plurality of transfer rollers include a paper ejection roller provided at a downstream end of the document transfer path and set to have a slower document transfer speed than other transfer rollers.
The paper ejection roller includes a roller pair provided so that one roller can be detached from the other roller.
In the control unit, the rear end portion of the preceding document and the front end portion of the succeeding document are arranged on the upstream side of one of the other transport rollers, the paper discharge roller, and the paper discharge before paper discharge roller and the paper discharge. The document transport operation of the plurality of transport rollers is controlled so as to overlap each other at the positions between the paper rollers, and the other transport rollers and the paper discharge roller are used during document transport by the plurality of transport rollers. A document feeder that controls the detachment operation of the paper ejection roller so that the same document is not sandwiched at the same time. The control unit separates the paper ejection roller immediately before the tip of the document reaches the paper ejection roller, and hits the paper ejection roller immediately after the rear end of the document passes through the paper ejection pre-conveying roller. The document feeder according to claim 1, which is in a contact state. The document feeder according to claim 1 or 2, further comprising an upper transport guide provided at a position between the pre-paper ejection transport roller and the paper ejection roller and extending diagonally downward toward the downstream side. The document feeding device according to any one of claims 1 to 3, wherein the paper ejection roller is arranged at a position shifted downward with respect to the document transporting direction by the pre-paper ejection transport roller. The paper ejection roller includes a plurality of roller pairs arranged at predetermined intervals in the document transport direction.
The document feeding device according to any one of claims 1 to 4, wherein at least the most upstream roller pair is provided so as to be detachable from the plurality of roller pairs. An image reading device comprising the document feeding device according to any one of claims 1 to 5. An image forming apparatus comprising the image reading apparatus according to claim 6. This is a document transport method in a document feeder that is equipped with a plurality of transport rollers provided in the document transport path and can continuously transport documents from the document loading tray on which the documents are loaded to the document ejection tray via the image reading position. hand,
(A) Of the plurality of transport rollers, the document transport speed of the paper ejection roller provided at the downstream end of the document transport path is set to be slower than the document transport speed of the other transport rollers, and the paper is preceded. The position between the rear end of the document and the front end of the subsequent document between the pre-discharge transfer roller and the output roller arranged on the upstream side of one of the other transfer rollers. In the step of transporting documents by the plurality of transport rollers and (b) when the documents are transported by the plurality of transport rollers, the other transport rollers and the paper ejection roller are simultaneously the same document. A method for transporting a document, which comprises a step of separating and contacting the paper ejection roller so as not to be in a state of sandwiching the paper.

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