JP3927343B2 - Automatic document feeder and image reading device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image reading apparatus such as a scanner, a copying machine, and a facsimile, and an automatic document feeder mounted thereon.
[0002]
[Prior art]
FIG. 9 is an overall configuration diagram of a conventional automatic document feeder, and FIG. 10 is an enlarged configuration diagram in the vicinity of the document reading position.
The automatic document feeder shown in FIG. 9 is known and includes a document table 2, a paper feed guide plate 3, a bottom plate 4, a separation mechanism unit, a paper discharge roller 12, a paper discharge unit 15, and the like. Since it is publicly known, its configuration will be briefly described together with the operation.
[0003]
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 a main body (not shown). The leading edge of the document 1 is positioned by abutting against the paper feed guide plate 3.
[0004]
The bottom plate 4 is raised in the direction of arrow A by a solenoid (not shown) in response to a paper feed start signal from the main body, and presses the document 1 against the calling member 5 from below. The pressed document 1 is conveyed by a calling member 5 to a separation unit including a sheet feeding member 6 and a separation member 7 and separated one by one from the top.
[0005]
The raised bottom plate 4 is lowered after a certain time from the start of paper feeding or after detecting the leading edge of the document by a registration sensor 9 described later. When the bottom plate 4 is lowered, the pressure between the bottom plate 4 and the calling member 5 applied to the document is released, and the time during which the second image surface of the document being conveyed is rubbed against the first image surface of the next document can be shortened. When the bottom plate 4 is lowered after a certain time from the start of feeding, it is desirable to set the time as short as possible.
[0006]
When the document 1 is only a single-sided image (first image surface), there is no second image surface, so the bottom plate 4 does not have to be lowered. The user can set whether single-sided scanning or double-sided scanning. The separated document 1 is transported to a first transport path 21 having a transport roller 8 and a transport driven roller 8a as first transport means. The registration sensor 9 detects the leading edge of the document, and matches the timing of passing the leading edge of the document to the reading unit 10 of the main body and the start of image reading.
[0007]
In the case of reading only the first image surface (single-sided mode), the document 1 is read by the reading unit 10 and then the intermediate conveyance roller 11, the intermediate conveyance driven roller 11a, which is the second conveyance means, The paper passes through a second conveyance path 22 having a paper roller 12 and a driven roller 12a under discharge, and is discharged to the paper discharge unit 15.
[0008]
A paper discharge sensor 13 is judged to be jammed when the leading edge of the document does not reach the paper discharge sensor 13 even after a lapse of a certain time, or when the trailing edge of the document does not pass the paper discharge sensor 13 even after a lapse of a certain time. . Reference numeral 14 denotes a switching claw, which is normally held at the B position.
[0009]
In the case of reading the first image plane and the second image plane (double-sided mode), after reading the first image plane, it is detected that the leading edge of the document has reached the paper discharge sensor 13 through the second conveyance path 22. Alternatively, at the timing from the detection of the registration sensor 9, the switching claw 14 is lowered to the position B 'by a solenoid (not shown), passes through the third conveyance path 23 having the reverse roller 16 and the reverse driven roller 16a, and intermediate It is conveyed onto the tray 17.
[0010]
The switching claw 14 is not shown after the document trailing edge has passed through the paper discharge sensor 13 and a predetermined time has elapsed (time until the document trailing edge passes through the paper discharge roller 12 and reaches the switching claw 14). When the solenoid is released, it returns to the position B. After the switching claw 14 returns, the reverse roller 16 rotates in the reverse direction, and the leading edge of the document enters the nip portion between the paper discharge roller 12 and the paper discharge upper driven roller 12b.
[0011]
At this time, the paper discharge roller 12 is stopped, and so-called skew correction (document bending) is corrected. After completion of the abutting correction, the document 1 passes through the fourth conveyance path 24 and the first conveyance path 21 and the image information on the second image plane is read by the reading unit 10.
[0012]
When the second image surface is read and then discharged through the second conveyance path 22 to the paper discharge unit 15 as it is, the second image surface is stacked downward, and the page order of the document is out of order. The original 1 passes through the second transport path 22 and the switching claw 14 descends to the position B ′ so that the first image surface is stacked downward, and further passes through the third transport path 23 and on the intermediate tray 17. Then, the switching claw 14 returns to the position B, and is discharged to the paper discharge unit 15 through the fourth transport path 24, the first transport path 21, and the second transport path 22.
[0013]
As shown in FIG. 10, the lower side of the conveying path is in contact with the tangent line between the reading guide member 102 facing the contact glass 101 on the image forming apparatus main body side and the intermediate conveying roller 11 as the second conveying means on the downstream side. The front end of the main body reading unit guide 100 provided on the image forming apparatus main body side is located. The document conveyed by the conveying roller 8 passes the reading position C along the reading guide member 102, hits the main body reading unit guide 100, is guided upward, and is inserted into the conveying roller 11.
[0014]
[Problems to be solved by the invention]
In the conventional automatic document feeder, as shown in FIG. 10, it is necessary to provide a gap necessary for the passage of the document between the reading guide member 102 and the contact glass 101, and when the scanned document moves up and down in the gap ( For example, at the moment when the leading edge of the document hits the main body reading unit guide 100 and the moment when the trailing edge of the document passes through the transport roller 8, the document is conveyed while being stuck to the reading guide member 102 in a normal state. The original image is instantaneously in a state as shown by the broken line in FIG. 10), and the read image information is not stored accurately, and the image is stretched or contracted.
[0015]
On the basis of such background, for example, in Japanese Patent Laid-Open No. 8-254762, the driving of the belt driving roller is stopped until the leading edge reaches the reading position after the leading edge of the document is detected by the registration sensor. The belt roller conveys the document at a slower speed than the paper feed drive roller when a predetermined time has elapsed after reaching or has reached a predetermined number of pulses, and the read image is not stretched or contracted with high accuracy. The technology that makes it read in is proposed. However, the control becomes complicated.
[0016]
Japanese Patent Laid-Open No. 8-254765 discloses a driven roller provided on the downstream side in the document transport direction of an endless belt that sucks a document fed to a reading position and discharges the document toward a discharge roller. A technique has been proposed in which the above-described effect is obtained by separating the contactless glass upward from the contact glass so that the endless belt is inclined at a predetermined angle with respect to the contact glass. However, since the endless belt is provided, the size is increased, and the control mechanism is complicated.
[0017]
By the way, it has been widely known that a paper feeding roller is hollow and a suction hole is formed around the entire circumference to adsorb paper (for example, Japanese Patent Laid-Open No. 5-286597, Japanese Utility Model Laid-Open No. 5-6893). Issue gazette).
[0018]
The present invention has been made in view of the above circumstances, and an object thereof is to provide an automatic document feeder and an image reading apparatus capable of performing accurate and highly accurate reading on the image forming apparatus main body side.
[0019]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, in the automatic document feeder for reading image information while conveying a document, the conveyance roller disposed above the reading unit is hollow and has a large number of holes around it. It is formed and is configured to have a negative pressure inside.
[0020]
In order to achieve the above object, in the automatic document feeder of the present invention, when the document is read using the pressure plate, the conveyance roller is positioned inside the reference scale that regulates the document edge. It is mounted on a reading device.
[0021]
In order to achieve the above object, in the automatic document feeder of the present invention , an openable / closable lid is provided between the conveying roller and the contact glass.
[0022]
In order to achieve the above object, in the automatic document feeder of the present invention , the lid is configured to open at the same time as the document is set.
[0023]
According to a second aspect of the present invention, in the automatic document feeder according to the first aspect of the present invention, the conveying roller has a concave portion formed at an arbitrary position in the axial direction, and a peeling claw is brought into contact with the concave portion. It is characterized by having made it.
[0024]
Also, in the automatic document feeder for reading image information while conveying the originals, the paper discharge direction tip of the sheet discharge unit for discharging the original, the leading edge of the sheet discharge document discharge portion and the pressure plate sheet and the It is good also as what provided the opening part for conveyance guidance in between.
[0025]
According to a third aspect of the present invention, an automatic document feeder according to the first aspect is mounted, and the image reading apparatus reads an image from below the contact glass facing the conveying roller.
[0026]
In the present invention, since the read original is sucked and conveyed by the conveyance roller, it is caused by a change in speed that occurs when the leading edge of the original hits a guide or the like, or by a shock when the trailing edge of the original comes off the conveyance roller. There is no change in speed, and more accurate image information is read. In addition, by sucking the document onto the transport roller, abnormal images (streaks in the transport direction) generated by dust between the document and the contact glass can be eliminated, and the image information of the document can be read more accurately. Is called.
[0027]
In the present invention, the entire apparatus is reduced in size by disposing the conveying roller inside the reference scale. Further, the contact glass is made common when the pressure plate is used and when the automatic document feeder is used.
[0028]
In the present invention, by providing an openable / closable lid between the conveyance roller and the contact glass, the original is accurately pressed by the lid when the pressure plate needs to be pressed against the reference scale, and is attached to the conveyance roller. Dirt is prevented.
[0029]
In the present invention, the lid is opened simultaneously with the setting of the document, thereby eliminating the user's erroneous operation and troublesomeness.
[0030]
In the second aspect of the present invention, the conveyance roller is provided with a concave portion, and the peeling claw is brought into contact with the concave portion, whereby the sucked original is reliably guided to the next conveyance roller direction.
[0031]
In addition, an opening is provided at the front end of the paper discharge section for discharging the original, and the front end of the discharged paper is guided between the paper discharge section and the platen to automatically feed even long documents. It is stored without protruding outside the device.
[0032]
According to a third aspect of the present invention, the automatic document feeder according to the first aspect is provided, and there is no change in speed when the read original is sucked by the conveyance roller and conveyed, and is generated due to dust between the original and the contact glass. There is provided an image reading apparatus that can read image information more accurately without abnormal images.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram in the vicinity of a reading position in the automatic document feeder of the first embodiment, FIG. 2 is a perspective view of the reading and conveying roller, and FIG. 3 is a sectional view of the reading and conveying roller and the vicinity thereof.
[0034]
At the reading position C, a pipe-shaped reading and conveying roller 50 having a large number of holes 50a formed in the outer peripheral portion is provided on the upper part of the contact glass of the image forming apparatus. As shown in FIG. 3 to be described later, the inside of the reading conveyance roller 50 has a negative pressure.
[0035]
The document transported from the transport roller 8 is guided to the reading position along the guide 70, and is read and transported in the direction of the arrow 51 (counterclockwise direction) through the suction hole 50a provided in the read transport roller 50. Adsorbed to the roller 50 and conveyed. The sucked document is peeled off from the reading and conveying roller 50 by the provided mylar 52 so as to come into contact with the reading and conveying roller 50 and is conveyed toward the intermediate conveying roller 11.
[0036]
In this embodiment, the contact glass 74 for reading a document using the pressure plate 72 is provided separately from the contact glass 101 for the automatic document feeder, and is outside the reference scale 71 that regulates the edge of the document. There is a reading position for an automatic document feeder. Reference numeral 73 denotes a sheet on the lower surface of the pressure plate 72.
[0037]
As shown in FIG. 3, the reading / conveying roller 50 is formed of a pipe having a plurality of holes 50 a, one end of which is sealed by press-fitting the shaft 50 b or the like, and is supported by a bearing 53 a serving as a rotation center by a side plate 55. It has been. The other end of the reading / conveying roller 50 is constituted by a hollow shaft 50c and supported by the side plate 54 via a bearing 53b.
[0038]
The gear 58 is a gear for transmitting driving for rotating the reading and conveying roller 50. The hollow shaft 50c is supported at one end by a bearing 53c and connected to a pipe 56 connected to a suction machine (not shown). By the air pulled by the suction machine, the air inside the reading conveyance roller 50 is sucked in the direction of the arrow 57 from the hole 50a.
[0039]
FIG. 4 is a configuration diagram in the vicinity of a reading position in the automatic document feeder according to the second embodiment.
In this embodiment, a contact glass for reading an original using an automatic document feeder and a contact glass for reading an original using the pressure plate 72 (a common contact glass 75) are used in common. The reading and conveying roller 50 is disposed so as to be located on the inner side of the 60 (on the pressure plate 72 side) and above the sheet 70.
[0040]
Thus, in the example of FIG. 1, the distance from the end of the image forming apparatus main body to the inside of the reference scale 71 is L1, whereas in the example of FIG. 4, the distance from the end of the image forming apparatus main body to the reference. The distance to the inside of the scale 60 is L2, which is shorter than L1, and the apparatus can be miniaturized.
[0041]
FIG. 5 is a configuration diagram in the vicinity of a reading position in the automatic document feeder according to the third embodiment.
The third embodiment is a modification of the second embodiment, and an openable / closable lid 61 is provided so as to hide the lower surface of the reading conveyance roller 50. The openable / closable lid 61 is rotated and held at the position 61a or 61b in an open state when the automatic document feeder is used. This opening and closing is performed by a drive source (not shown) at the same time when the document is set in the automatic document feeder, and is held in the state of 61a and 61b from the position of the solid line shown by 61, and the last document is discharged. At the same time, the original state is restored.
[0042]
FIG. 6 is a configuration diagram in the vicinity of a reading position in the automatic document feeder according to the fourth embodiment, and FIG. 7 is a perspective view of the reading conveyance roller.
The fourth embodiment is also a modification of the second embodiment, and the reading conveyance roller 50 is disposed inside the reference scale 60. In this example, a concave portion 50e is provided in a part of the reading and conveying roller 50, and a separation claw 65 for separating the original adsorbed in the concave portion 50e is provided. Note that the hole 50a is not formed in the inner surface of the recess 50e.
[0043]
FIG. 8 is a view showing a guide structure of the discharged document edge.
As described above with reference to FIG. 9, the document discharged from the paper discharge roller 12 is sent to the paper discharge unit 15. In this example, an opening 15a is provided at the front end of the paper discharge unit 15 in the paper discharge direction, and a regulation piece 80 for guiding the document end to the opening 15a is provided. When the document to be discharged is long, the leading edge of the document is guided from the discharging section 15 to the opening portion 15 a and is guided to the sheet 73.
[0044]
【The invention's effect】
According to the present invention, since the read document is sucked and transported to the transport roller, the speed change that occurs when the leading edge of the document hits the guide or the like, or when the rear end of the document is separated from the transport roller. There is no speed change due to shock, and more accurate image information can be read. In addition, by sucking the document onto the transport roller, it is possible to eliminate abnormal images (streaks in the transport direction) caused by dust between the document and the contact glass, and to read the image information of the document more accurately. it can.
[0045]
According to the present invention, the entire apparatus can be reduced in size by disposing the transport roller inside the reference scale. Further, the contact glass can be made common when the pressure plate is used and when the automatic document feeder is used.
[0046]
According to the present invention, by providing an openable / closable lid between the transport roller and the contact glass, the original can be accurately pressed by the lid when the pressure plate needs to be pressed against the reference scale. Dirt adhering to the conveying roller can be prevented.
[0047]
According to the present invention, by opening the lid at the same time as setting the document, it is possible to eliminate the user's erroneous operation and troublesomeness (the effect of the present invention is sufficient even manually, but by interlocking with the document set, Easier to use).
[0048]
According to the second aspect of the present invention, it is possible to reliably guide the sucked original in the direction of the next conveyance roller by providing the conveyance roller with the concave portion and bringing the peeling claw into contact with the concave portion.
[0049]
Further, an opening is provided in the paper discharge direction leading end of the sheet discharge unit for discharging the originals, by conveying guiding the leading end of the sheet discharge document between the sheet discharge portion and the platen, automatic document even in a long document It can be stored without protruding outside the feeder.
[0050]
According to a third aspect of the present invention, the automatic document feeder according to the first aspect is provided, and there is no change in speed when the read original is sucked by the conveying roller and conveyed, and dust or the like between the original and the contact glass is used. It is possible to provide an image reading apparatus that does not generate an abnormal image or the like and can read image information more accurately.
[Brief description of the drawings]
FIG. 1 is a configuration diagram in the vicinity of a reading position in an automatic document feeder according to a first embodiment.
FIG. 2 is a perspective view of a reading conveyance roller shown in FIG.
FIG. 3 is a cross-sectional view of the reading conveyance roller shown in FIG. 1 and the vicinity thereof.
FIG. 4 is a configuration diagram in the vicinity of a reading position in an automatic document feeder according to a second embodiment.
FIG. 5 is a configuration diagram in the vicinity of a reading position in an automatic document feeder according to a third embodiment.
FIG. 6 is a configuration diagram in the vicinity of a reading position in an automatic document feeder according to a fourth embodiment.
7 is a perspective view of the reading conveyance roller shown in FIG. 6. FIG.
FIG. 8 is a diagram illustrating a guide structure of a discharged document edge.
FIG. 9 is an overall configuration diagram of a conventional automatic document feeder.
10 is an enlarged configuration diagram in the vicinity of a document reading position of the automatic document feeder shown in FIG. 9;
[Explanation of symbols]
C Reading position 50 Reading conveyance roller 50a Hole

Claims (3)

In an automatic document feeder that reads image information while conveying a document,
Conveying rollers arranged in the reading unit upward, a large number of holes are formed around a hollow, and is configured such that the internal negative pressure occurs
It is mounted on the reading device so that the transport roller is positioned inside a reference scale that regulates the edge of the document when the document is read using the pressure plate ,
An openable / closable lid is provided between the conveying roller and the contact glass .
2. The automatic document feeder according to claim 1, wherein the lid is configured to open at the same time as the document is set . The automatic document feeder according to claim 1, wherein
2. An automatic document feeder according to claim 1, wherein the conveying roller is formed with a concave portion over the entire circumference at an arbitrary position in the axial direction, and a peeling claw is brought into contact with the concave portion.   2. An image reading apparatus, wherein the automatic document feeder according to claim 1 is mounted and an image is read from below a contact glass facing the conveying roller.

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