JP2004136998A - Sheet feeding device, and image reading apparatus and image forming apparatus having it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet feeding device capable of preventing increase of driving load of the sheet feeding device without damaging sheet feeding performance, and an image reading apparatus and an image forming apparatus having it. <P>SOLUTION: A position corresponding to a pickup roller 10 of a lower guide frame 21 is provided with an evacuating section 26 for inserting the pickup roller 10 so that the pickup roller 10 does not abut on the lower guide frame 21 when no sheet exists in the lower guide frame 21. A holding member 16 for holding the pickup roller 10 is provided with a regulating section 25 for abutting on the lower guide frame 21 to regulate the movement of the holding member 16 when no sheet exists in the lower guide frame 21. When no sheet exists and when the pickup roller 10 goes into the evacuating section 26, the regulating section 25 is butted on the lower guide frame 21 to regulate the movement of the holding member 16, and the pickup roller 10 is held in a floating state in the evacuating section. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sheet feeding apparatus, an image reading apparatus including the same, and an image forming apparatus, and more particularly to a configuration provided in the sheet feeding apparatus to prevent a driving load of a sheet feeding unit for feeding a sheet from increasing.
[0002]
[Prior art]
2. Description of the Related Art In a conventional image forming apparatus such as a copying machine or a facsimile, or an image reading apparatus such as a scanner, sheets supported by a sheet supporting unit are sequentially transferred one by one from a top one by a pickup roller as a sheet feeding unit. After the sheet is fed, a sheet feeding device for separating the sheet one by one by a separating unit and feeding the separated sheet to the image forming unit or the image reading unit is provided.
[0003]
Here, for example, in a document feeder which is provided in an image reading device and is an example of a sheet feeder for feeding a document as a sheet, a pickup roller is provided with a pickup arm which is rotatably provided in a vertical direction. It is rotatably held at the rotation end, and when sending out the original, the original is rotated by a downward rotation of the pickup arm and abuts at a predetermined pressure while rotating against the original placed and supported on the original placing table. Is sent out.
[0004]
By the way, in such a document feeder, when the last document has been sent out, the pickup roller 100 comes into direct contact with the document table 101 as shown in FIG. When the pickup roller 100 rotates, the frictional load between the pickup roller 100 and the document table 101 increases the driving load of a motor (not shown) that drives the pickup roller 100.
[0005]
For this reason, conventionally, a low friction member 102 such as Mylar (registered trademark of DuPont) is provided on the document table 101, and the pickup roller 100 is brought into contact with the low friction member 102 after the last document is discharged. By doing so, an increase in the driving load of the motor is prevented.
[0006]
[Problems to be solved by the invention]
However, in a document feeder (sheet feeder) provided with such a pickup roller, in order to improve the document feed performance in terms of the configuration or function of the device, for example, when the pressing force of the pickup roller is increased, Alternatively, if the direction of the pressing force of the pickup roller is further in the direction of biting the document table, the driving load increases, and as a result, the pickup roller may be brought into contact with the low friction member. The motor may lose synchronism.
[0007]
Therefore, in such a case, it is necessary to change the motor or the like, and in this case, there is a problem that the cost is increased.
[0008]
Accordingly, the present invention has been made in view of such a situation, and a sheet feeding apparatus capable of preventing an increase in driving load of a pickup roller (sheet feeding unit) without impairing document (sheet) feeding performance. It is an object of the present invention to provide a feeding device, an image reading device including the same, and an image forming device.
[0009]
[Means for Solving the Problems]
The present invention relates to a sheet feeding device for feeding a sheet supported by a sheet supporting portion, wherein the sheet feeding device is provided so as to be able to contact and separate from the sheet supported by the sheet supporting portion, and feeds the sheet; A movable holding member for holding the sheet feeding means so as to be able to contact and separate from the sheet; and a sheet supporting part provided at a position corresponding to the sheet feeding means. An evacuation section for inserting the sheet feeding means so that the sheet feeding means does not contact the section, and a sheet feeding means provided on the holding member, wherein the sheet feeding means is provided when the sheet feeding means enters the evacuation section. And a restricting portion for restricting the movement of the holding member by contacting the sheet supporting portion so as to hold the floating member in the retracting portion.
[0010]
Further, the present invention is characterized in that the regulating portion of the holding member is provided in a direction perpendicular to a sheet conveying direction of the sheet feeding means and at a central portion of the sheet supporting portion.
[0011]
Further, the present invention is characterized in that an elastic member which bends while abutting on the sheet feeding means when the sheet feeding means enters the retreating section is provided in the retracting section.
[0012]
According to another aspect of the present invention, there is provided an image reading apparatus comprising: an image reading unit that reads an image of a sheet; and the sheet feeding device according to any one of the above, which feeds a sheet to the image reading unit. Things.
[0013]
According to another aspect of the invention, an image forming apparatus includes: an image forming unit that forms an image on a sheet; and the sheet feeding device according to any one of the above, which feeds a sheet to the image forming unit. Is what you do.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0015]
FIG. 2 is a perspective view of an image reading apparatus provided with a document feeding apparatus which is an example of a sheet feeding apparatus according to an embodiment of the present invention. In FIG. This is a document feeder attached to the upper part of the device 50. Reference numeral 2 denotes a document table, reference numeral 3 denotes a document discharge table, and reference numeral 4 denotes a document table. The document table 2 moves in a width direction orthogonal to the document conveyance direction to align both sides of the document placed on the document table 4. It is a slider.
[0016]
Reference numeral 1A denotes an apparatus main body of the document feeding apparatus 1. Inside the apparatus main body 1A, a substantially U-shaped document conveying path (hereinafter, referred to as a U-turn path) 14 is provided as shown in FIG. Have been. A lower guide frame 21 that forms a sheet support together with the document placing table 2 is provided so as to be connected to the upstream end side of the U-turn path 14, and the document discharge table 3 is connected to the downstream end side of the U-turn path 14. Is provided.
[0017]
An upstream portion of the U-turn path 14 is provided with a pickup roller 10 serving as a sheet feeding unit that comes into contact with and sends out the uppermost original S1 of the originals S stacked on the original placing table 2 and a pickup roller 10. A separation pad 15 that constitutes a separation unit that separates the fed document S1 one by one, a separation roller 5 that presses against the separation pad 15, and a document that regulates the leading end position of the document S stacked on the document mounting table 2. A stopper 9 and a document presence / absence sensor 6 for detecting the presence / absence of the document S on the document table are provided.
[0018]
Further, a document discharge roller pair 11 for discharging the document S to the document discharge table 3 and a document edge sensor 8 for detecting a leading end and a trailing end of the document S are provided at a downstream end side of the U-turn path 14. Have been.
[0019]
In FIG. 1, reference numeral 7 denotes a transport roller for transporting the document S while pinching the document S together with the transport rollers 17 to 20, and 16 a pickup arm rotatably provided coaxially with the shaft 5a of the separation roller 5. The pickup roller 10 is rotatably held at a rotating end of the pickup arm 16.
[0020]
The pickup roller 16 disposed above the lower guide frame 21 is held by the pickup arm 16 serving as the holding means so as to be able to approach and separate from the document S. It comes into contact with the document S while rotating with the downward rotation.
[0021]
Here, when the operator places the document S on the document table 2 and sets it, the document S is moved from right to left in the left-right direction of the document feeder 1, and The original is set so that the image surface is on the upper side. When the original is set, the position of the leading end of the original S is regulated by the original stopper 9, and the presence of the original is detected by the original presence / absence sensor 6. Has become. The document stopper 9 is pushed down by the pickup arm 16 when the pickup arm 16 rotates downward as described later.
[0022]
Reference numeral 1B denotes an image reading unit for reading the document S conveyed by the pickup roller 10 and the conveyance roller 7. The image reading unit 1B includes a reading glass 12 and a contact image sensor 13 provided below the reading glass 12. And
[0023]
Here, the contact image sensor 13 irradiates the image information surface of the document S with light from an LED array (not shown) as a light source, and reflects the reflected light from the image information surface with a sensor element using a selfoc lens (trademark). And image information is read.
[0024]
In such an image reading apparatus 1, when the operator instructs the start of reading from an operation unit (not shown), the motor (not shown) first rotates and the pickup arm 16 rotates downward. Depressed. Thereafter, the pickup roller 10 abuts on the uppermost original S1 of the originals S stacked on the original placing table 2, and sends out the uppermost original S1.
[0025]
Next, the uppermost document S1 passes through the upper end surface of the pressed document stopper 9, is separated from other documents by the separation roller 5 and the separation pad 15, and is fed into the U-turn path. Further, the document S1 sent into the U-turn path 14 in this manner is conveyed by rollers 17 to 19 facing the conveying roller 7 toward a reading position where image information is read by the contact image sensor 13. .
[0026]
Next, when the leading edge of the document S1 is detected by the document edge sensor 8, reading of image information by the contact image sensor 13 is started when the document S1 is conveyed by a predetermined amount from that position. When the trailing edge of the document S1 is detected by the document edge sensor 8, the reading of the image information by the contact image sensor 13 is terminated when the document is conveyed by a predetermined amount from that position.
[0027]
Next, the document S <b> 1 is discharged to the document discharge table 3 by the discharge rollers 11. In this manner, the image reading device 50 repeats the above-described reading operation until the document presence sensor 6 detects that there is no document.
[0028]
FIG. 1 is a diagram showing a state when the reading operation is repeated in this manner and the final document is sent out. Here, as shown in the figure, a concave portion 26 which is a retracting portion is formed at a position corresponding to the pickup roller 10 of the lower guide frame 21. Then, when the final document is sent out, there is no longer a document that has covered the concave portion 26 so that the pickup roller 10 enters the concave portion 26.
[0029]
Reference numeral 25 denotes an abutting portion which is a restricting portion formed at the rotating end of the pick-up arm 16, and when the final document is sent out and the pickup roller 10 enters the concave portion 26, the abutting portion 25 is As shown in FIG. When the abutting portion 25 abuts on the lower guide frame 21 in this manner, the downward rotation of the pickup arm 16 is restricted, and the pickup roller 10 that has entered the recess 26 does not hit the bottom surface of the recess 26. It can be held.
[0030]
That is, in the present embodiment, when the final document passes through the pickup roller 10, the pickup roller 10 enters the recess 26 while rotating the pickup arm 16 downward, and the abutting portion of the pickup arm 16 that has rotated downward. The rotation of the pickup arm 16 is restricted by the contact of the lower arm 25 with the lower guide frame 21, whereby the pickup roller 10 that has entered the recess 26 is held in a floating state in the recess.
[0031]
By holding the pickup roller 10 in a floating state in the recess as described above, the pickup roller 10 does not come into contact with the lower guide frame 21. As a result, even if the pickup roller 10 rotates, extra driving is performed. Since no load is received, the drive load does not increase and a stable drive load can be obtained. The abutting portion 25 is provided at the center in the width direction of the pickup roller 10 so that the document does not skew even when the document abuts on the document.
[0032]
When the last original is sent out, the original is sandwiched between the abutting portion 25 and the lower guide frame 21. By picking up the pickup roller 10 into the concave portion 26, the original conveyance force is utilized by utilizing the rigidity of the original. Therefore, the last document can be sent out without fail.
[0033]
In order to more reliably convey the document, an elastic member 27 such as a mylar is provided on the lower guide frame 21 so as to cover at least a part of the concave portion 26 as shown in FIGS. 5 and 6, for example. When the pickup roller 10 enters the concave portion 26, the elastic member 27 is brought into contact with the pickup roller 10 so that the elastic member 27 is caused to enter the concave portion 26 while being bent. With this configuration, the document conveying force can be increased by utilizing the bending rigidity of the elastic member 27.
[0034]
In the above, the shape of the evacuation portion into which the pickup roller 10 enters is a concave portion, but the present invention is not limited to this, and the shape of the evacuation portion may be a hole shape opened in the up-down direction.
[0035]
Also, although an image reading apparatus using the original feeding apparatus of the present invention has been described above, the present invention is not limited to this, and a sheet is applied to the image forming section in an image forming apparatus having an image forming section. The sheet feeding device of the present invention may be used as a sheet feeding device for feeding.
[0036]
The image forming apparatus further includes an image reading unit, a document feeding device that feeds a document to the image reading unit, and an image forming unit that forms an image based on document information read by the image reading unit. The sheet feeding device of the present invention may be used as a sheet feeding device for feeding a sheet to the reading unit.
[0037]
【The invention's effect】
As described above, when the sheet does not exist in the sheet supporting portion as in the present invention, the sheet feeding means is inserted into the evacuation portion provided at a position corresponding to the sheet feeding means of the sheet supporting portion, and is held. By contacting the regulating portion provided on the member with the sheet supporting portion, when the sheet feeding means enters the retreating portion, the sheet feeding means can be held in a state of being floated in the retreating portion. An increase in the driving load of the sheet feeding means can be prevented without impairing the sheet feeding performance.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a state when a final document is fed out of a document feeding device which is an example of a sheet feeding device according to a first embodiment of the present invention.
FIG. 2 is a perspective view of an image reading apparatus provided with the document feeding device.
FIG. 3 is a diagram showing a schematic configuration of the document feeder.
FIG. 4 is an essential part perspective view showing a state where the last document is sent out by the document feeding apparatus.
FIG. 5 is a diagram illustrating a state when a final document is fed out of a document feeding device which is an example of a sheet feeding device according to a second embodiment of the present invention.
FIG. 6 is an essential part perspective view showing a state when the last original is sent out by the original feeding device.
FIG. 7 is a diagram showing a state when a final document is sent out of the conventional document feeding apparatus.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 document feeding device 1A device main body 1B image reading unit 2 document mounting table 10 pickup roller 16 pickup arm 21 lower guide frame 25 butting portion 26 recess 27 elastic member 50 image reading device S document

Claims (5)

In a sheet feeding device that feeds a sheet supported by a sheet supporting unit,
A sheet feeding unit that is provided so as to be able to contact and separate from the sheet supported by the sheet supporting unit, and feeds the sheet.
A movable holding member that holds the sheet feeding means so as to be able to contact and separate from the sheet,
The sheet supporting unit is provided at a position corresponding to the sheet feeding unit, and when there is no sheet in the sheet supporting unit, the sheet feeding unit is inserted so that the sheet feeding unit does not contact the sheet supporting unit. Evacuation unit,
The holding member is provided on the holding member, and when the sheet feeding means enters the retreat portion, the sheet feeding means abuts on the sheet support portion so as to be held in a floating state in the retreat portion, and the holding member moves. A regulatory department that regulates
A sheet feeding device comprising: 2. The sheet feeding device according to claim 1, wherein the regulating portion of the holding member is provided in a direction perpendicular to a sheet conveying direction of the sheet feeding means and at a central portion of the sheet supporting portion. 3. The sheet feeding device according to claim 1, wherein an elastic member that bends while contacting the sheet feeding means when the sheet feeding means enters the retreating section is provided in the retracting section. . An image reading apparatus comprising: an image reading unit that reads an image of a sheet; and the sheet feeding device according to claim 1 that feeds the sheet to the image reading unit. An image forming apparatus comprising: an image forming unit that forms an image on a sheet; and the sheet feeding device according to claim 1 that feeds the sheet to the image forming unit. .

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