JPH11106071A - Sheet feeding device and image reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet feeding device and an image reading device whereby it is possible to make sheet feed control without using a level sensing lever and to enhance the sheet feeding performance. SOLUTION: A vacuum suction sheet feeding means 2 is installed over an accommodating member 12 which accommodates sheets in a stack and is arranged capable of elevating and sinking, and by this means 2, each sheet accommodated by the accommodating member 12 coming up is sucked by vacuum and transported in the sheet feed direction. A suction static pressure sensing means 9 is furnished to sense the suction static pressure of the sheet feeding means 2, and on the basis of the static pressure information given by the pressure sensing means 9, a control means judges that the sheet is attracted to the means 2, when the sensed pressure has exceeded the specified level, and starts the sheet transporting operation through controlling of the means 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus which is arranged in an image reading apparatus such as a copying machine or a facsimile and feeds a sheet to a main body of the image reading apparatus. About what you do.

[0002]

2. Description of the Related Art Conventionally, in an image reading apparatus such as a copier or a facsimile, when a bundle of originals stacked for image formation is quickly fed to a platen to read an image, the risk of damaging the originals is eliminated. In addition, in order to minimize the stoppage of the apparatus due to a jam or a double feed of originals, a malfunction must be prevented. The greatest problem arises when separating a document bundle on which individual documents are stacked.

Heretofore, the separation of the original bundle has conventionally been performed by friction using a roller or a belt, for example. In the friction separation using such a separation roller or a belt, reliable separation and feeding are performed. The image surface of the original was rubbed and soiled, and the edge of the original became dirty due to friction separation by a belt, causing damage to the original.

Therefore, in order to surely separate the originals without causing any damage in the original feeding operation, for example, as shown in FIG. In this case, the upper document is fed separately by injecting air and feeding the document by gas injection means 14 for separating the uppermost document 1a.

In such a sheet feeding apparatus, the rear end regulating portion 10 of the upstream end of the original 1 in the transport direction is used.
And a document storage tray 12 serving as a storage member for loading and storing documents (sheets) based on the rotation angle of the height detection lever 11.
Is moved up and down so that the original surface is positioned at an appropriate height with respect to the vacuum suction feeding means 2.

[0006]

However, in such a conventional sheet feeding apparatus, the weight of the height detecting lever 11 causes the uppermost original 1a to move between the uppermost original 1a and the second and subsequent originals. The frictional force increases, and the top document 1
a cannot be separated when paper is fed, and the second sheet 1b below the uppermost document 1a is also fed, which causes a problem of double feeding.

Further, when the upper document is fed, the next document is taken out and the leading edge position of the document fluctuates, and this fluctuates the feeding timing, which hinders the control of the interval between small sheets.

Further, in the paper feeding by the vacuum suction paper feeding means 2, the time required for the static suction pressure to rise differs depending on the type of the document, or it takes 100 ms until the suction is started and the pressure reaches the pressure at which the document can be reliably attracted. The control must be performed in consideration of the above-mentioned time lag, and the interval between paper sheets cannot be reduced.

Therefore, the present invention has been made to solve such a conventional problem, and it is possible to perform paper feed control without using a height detection lever and to improve paper feed performance. It is an object of the present invention to provide a sheet feeding apparatus capable of performing the above-described operations and an image reading apparatus including the same.

[0010]

SUMMARY OF THE INVENTION The present invention is directed to a storage member capable of loading and storing sheets and moving up and down, and a sheet stored in the storage member which is disposed above or below the storage member and which has been raised or lowered. Suction paper feeding means for sucking and transporting the paper in the paper feeding direction by vacuum suction, static suction pressure detecting means for detecting the static suction pressure of the vacuum suction paper feeding means, and static pressure from the static suction pressure detecting means. And control means for setting the paper feed timing of the vacuum suction paper feed means based on the pressure information.

Further, according to the present invention, the control means determines that the sheet has been attracted to the vacuum suction sheet feeding means when the static pressure becomes equal to or higher than a predetermined pressure based on the static pressure information, and performs a sheet conveying operation. The vacuum suction sheet feeding means is controlled so as to start.

Further, the present invention is characterized in that the control means controls the vacuum suction paper feeding means so as to start sheet conveyance after a predetermined time has elapsed since the static pressure became equal to or higher than a predetermined pressure. Is what you do.

[0013] The present invention may further comprise a lifting means for raising and lowering the storage member, wherein the control means determines that the predetermined static pressure is lower than the predetermined pressure before the static suction pressure detecting means detects the predetermined pressure. When the detection is made, the drive of the lifting / lowering means is controlled so that the rising speed of the storage member is lower than the speed before the other predetermined pressure is reached.

Further, according to the present invention, the control means determines that the sheet has been attracted to the vacuum suction sheet feeding means when the static pressure rise amount in a predetermined time exceeds a predetermined amount based on the static pressure information. Then, the vacuum suction sheet feeding means is controlled so as to start the sheet conveying operation.

Further, according to the present invention, there is provided an image reading apparatus provided with a sheet feeding device and an image reading section, wherein the sheet feeding device is one according to any one of claims 1 to 5. Is what you do.

Further, as in the present invention, the sheets stored in the ascending storage member are supplied by vacuum suction by means of a vacuum suction paper feeding means disposed above the storage member capable of stacking and storing the sheets and moving up and down. Convey in the paper direction. Further, the control means is configured to, based on the static pressure information from the static suction pressure detecting means for detecting the static suction pressure of the vacuum suction paper feeding means, cause the sheet to be attracted to the vacuum suction paper feeding means when the static pressure exceeds a predetermined amount. It is determined that the sheet feeding operation has been performed, and the sheet feeding operation is started by controlling the vacuum suction sheet feeding means.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of an image reading apparatus provided with a sheet feeding device according to an embodiment of the present invention. In addition,
8, the same reference numerals as those in FIG. 8 indicate the same or corresponding parts.

In FIG. 1, reference numeral 1A denotes an image reading apparatus, and 1B
Reference numeral 1 denotes a sheet feeding device, which is a sheet-like document (hereinafter, referred to as a document) 1 which is loaded on a storage tray 12 of the sheet feeding device 1B and records image information such as paper or synthetic resin.
Is transported by the vacuum suction paper feeding means 2 and the transport roller 30, and thereafter, the image reading apparatus main body (hereinafter referred to as the main body) 1
It passes through a fixed exposure unit 4 through a transport path 3 provided inside A1.

At this time, the image of the original 1 is read by the optical system of the fixed scanner 5 which is an image reading section, and the original 1 after the reading is carried by the roller 31 in the direction shown by the arrow. The document is discharged to the document discharge tray 7.

The document flow indicated by the arrow in FIG. 1 indicates a case where image information recorded on one side of the document 1 is read. FIG. 2 shows a case in which image information recorded on both sides of the original 1 is read.
It shows the flow. Here, when reading the double-sided image of the original 1, as described above, the original 1 whose first surface has passed through the exposure unit 4 is inverted inside the main body 21a by the switching means 6 for switching between double-sided inversion and discharge. Then, the image information on the front and back surfaces of the original 1 is read by passing the second surface again through the exposure unit 4, and thereafter, the original 1 is discharged onto the original discharge tray 7.

FIG. 3 shows reading in the book mode. Reading in the book mode is performed by moving the optical system 5 on a document fixed on the pressure plate section 8.

As shown in FIG. 4, the vacuum suction feeding means 2 has a plurality of suction openings 21 for sucking the original 1.
a and a suction duct 21 having a suction means (not shown);
An endless belt 23, which is stretched over a pair of pulleys 22 provided on both sides of the suction duct 21 and has a number of holes (not shown) for adsorbing a document, and the pulley 22 is driven to rotate. Driving means 27 shown in FIG. 5 described below for driving the endless belt 23 is provided.

Further, the vacuum suction paper feeding means 2 is provided with a static pressure detecting means 9 for detecting a static suction pressure inside the suction duct. When the suction is started, the static pressure detecting means 9 moves the document surface along with the suction opening 21 as the storage tray 12 rises.
a, and the suction static pressure inside the suction duct approaches the first predetermined pressure,
In the present embodiment, when it is detected that 18 mmAq has been reached, a first detection signal is output, and a second predetermined pressure, which is a pressure indicating that the suction static pressure has attracted the original, is 21.3 mmAq in the present embodiment. Is detected, the second detection signal is input to a control device shown in FIG. 5 to be described later.

In FIG. 1, reference numeral 17 denotes a conveyed document detecting sensor which is a conveyed sheet detecting means provided between the vacuum suction sheet feeding means 2 and the convey roller 30. Also,
Reference numeral 18 denotes a tray document detecting unit 18 that is provided on the document storage tray 12 and detects that the document 1 is set on the document storage tray 12.

On the other hand, at a predetermined position of the sheet feeding device 1B, a control device 25 as control means shown in FIG. 5 is provided. In the figure, reference numeral 19 denotes, for example, an electromagnetic suction valve which is provided in the suction duct 21 of the vacuum suction paper feeding means 2 and whose opening and closing are controlled by the control device 25.
When the suction valve 19 is opened, the suction operation of the vacuum suction sheet feeding means 2 is started.

Here, the control device 25 controls a document detection signal from the tray document detection means 18 and an operation unit (not shown).
An image reading start signal is input from a switch SW provided in the storage unit 12. Based on these signals, the storage tray 12 is moved up and down so that the storage tray 12 approaches the vacuum suction feeding unit 2. The tray motor 13 (see FIG. 4) as a means is rotated forward.

Further, based on these signals, the control device 25 opens the suction valve 19 of the vacuum suction sheet feeding means 2 to start the suction operation, and separates air from the separation nozzle 14 (see FIG. 4). The operation is started.

When the first detection signal is input from the static pressure detecting means 9 which detects that the suction static pressure inside the suction duct has reached 18 mmAq, as described above, the control device 25 controls the storage tray. The rotation speed of the tray motor 13 is reduced so that the ascending speed (lift-up speed) of the tray motor 12 is slightly reduced from a predetermined first speed to a second speed.

Further, the static suction pressure inside the suction duct is 2
1.3 mmAq, and when the second detection signal indicating that the document is attracted to the endless belt 23 is input from the static pressure detecting means 9, the tray motor 13 is rotated in the reverse direction to lower the storage tray 12. I have. As described above, by lowering the ascending speed of the storage tray 12 from the first speed to the second speed before the second detection signal is input, the time required for stopping the storage tray 12 is increased. It is possible to prevent problems such as the original being pressed against the endless belt 23.

The control device 25 drives the endless belt 23 holding the original 1 by the driving means 27 in accordance with the second detection signal so that the original is conveyed toward the conveying roller 30. I have.

Further, thereafter, the fed document approaches the transport roller 30, and the transported document is detected by the transport document detection sensor 17.
, The suction valve 19 is closed to stop the suction of the vacuum suction sheet feeding means 2 and the driving of the endless belt 23 to be stopped, whereby the document is transported by the transport roller 30. Become like

On the other hand, the storage tray 12 is
When the predetermined amount, for example, the suction static pressure inside the suction duct becomes 0 by the reverse rotation of 3, and the signal drops from the static pressure detection sensor 9 to a position where a signal indicating that the pressure is detected is input, the tray motor 13 is stopped. To As a result, the document 1 other than the uppermost document 1a being sucked is surely separated by the separation effect of the separation nozzle 14. After that, when the document is fed again, the storage tray 12 moves up and down at the second speed.

Next, the document feeding operation of the sheet feeding apparatus thus configured will be described.

When the document 1 is set on the document storage tray 12, a detection signal is input from a document detection sensor 17 provided on the document storage tray 12, whereby the control device 2
Reference numeral 5 detects a document set. At the same time, the rear end regulating plate 1
0 is adjusted to the rear end of the original 1,
Identifies the length of the document 1 in the transport direction.

Next, when the switch SW is operated, the image reading of the original 1 is started, and at the same time, the tray motor 13 is rotated forward to bring the storage tray 12 close to the vacuum suction feeding means 2 at the first speed. Then, the suction valve 19 is opened to start suction by the vacuum suction paper feeding means 2. Separating nozzle 14 causes separation air to be blown out, and the uppermost document 1a of document 1 approaching the sheet feeding position is separated by the separation air and sucked by vacuum suction feeding means 2.

Next, when the document surface approaches the suction opening 21a with the rise of the storage tray 12, the suction static pressure inside the suction duct rises to 18 mmAq. The first detection signal is output, and the rotation speed of the tray motor 13 is reduced based on the first detection signal so that the ascending speed of the storage tray 12 becomes the second speed.

Thereafter, the storage tray 12 is further raised,
Eventually, the uppermost document 1a is attracted to the endless belt 23 of the vacuum suction / feeding means 2 as shown in FIG. 6, and due to this suction, the static suction pressure inside the suction duct becomes 21.3 mmAq,
When the second detection signal is input from the static pressure detecting means 9 detecting this, the tray motor 13 is rotated in the reverse direction to lower the storage tray 12, and the driving means 27 is driven to drive the endless belt 23, Feeding is started in the direction of arrow A.

Next, after the conveyed original detection sensor 17 detects the leading edge of the original and a detection signal is input from the conveyed original detection sensor 17, a predetermined time has elapsed and the original 1 a has hit the pull-out roller 15. Suction valve 19
Is closed to stop the suction operation of the vacuum suction paper feeding means 2 and the driving of the driving means 27, whereby the original 1a is conveyed only by the pull-out roller 15.

Thereafter, the next sheet feeding is performed. The timing of the next sheet feeding is set according to the document length, and the previous document 1a
The suction valve 19 of the vacuum suction paper feeding means 2 is opened at the timing when the rear end passes through the suction opening 21a of the vacuum suction paper feeding means 2.

At the same time, the document storage tray 12 is
When the static suction pressure reaches 21.3 mmAq, the document storage tray 12 is lowered and the endless belt 23 is driven. Thus, the operation of feeding the second original from the top is performed.

Then, with this configuration,
In the transport path 3 in which the preceding original 1a is additionally fed and acceleration control is performed, it is not necessary to gain a margin up to suction, and it is possible to provide a margin in the acceleration margin, and it is possible to realize small sheet interval control.

As described above, based on the static pressure information from the suction static pressure detecting means 17, the static pressure is set to the predetermined amount (21.3 mmAq).
At this time, it is determined that the sheet is sucked by the vacuum suction sheet feeding means 2 and the endless belt 23 is driven to start the sheet conveying operation, so that the sheet can be fed without using the height detecting lever. The control can be performed, and the paper feeding performance is improved.

On the other hand, after the original is conveyed in this manner, if the original 1 is exhausted and the tray original detecting means 18 detects that there is no original in the original storage tray 12, the original feeding is terminated and the original storage tray 12 is stopped. The tray motor 13
, And waits for the next document to be placed on the document storage tray 12. FIG. 7 is a timing chart of the document feeding operation of such a sheet feeding apparatus.

In the above description, the case has been described in which the control device 25 controls to start suction paper feeding when the suction static pressure inside the suction duct reaches a predetermined pressure. The static pressure rise amount detecting means for detecting the static pressure rise amount during a predetermined period of time is provided, and the static pressure rise amount detecting means detects when the static pressure rise amount becomes equal to or more than a predetermined amount. It may be configured to control to start feeding.

In the above description, a sheet feeding apparatus having a structure for sucking a document upward has been described. However, the present invention is not limited to this, and is applicable to a sheet feeding apparatus having a structure for sucking a document downward. It goes without saying that you can do it.

[0047]

As described above, according to the present invention, it is possible to determine that a sheet has been sucked by the vacuum suction sheet feeding means based on the static pressure information from the suction static pressure detecting means.
Paper feed control can be performed without using a height detection lever, and paper feed performance can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image reading apparatus including a sheet feeding device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a case where image information recorded on both sides of a document is read by the image reading apparatus.

FIG. 3 is a diagram showing reading in a book mode in the image reading apparatus.

FIG. 4 is a diagram illustrating a configuration of the sheet feeding device.

FIG. 5 is a block diagram of a control device of the sheet feeding device.

FIG. 6 is a view showing a state in which a top document is sucked by vacuum suction sheet feeding means of the sheet feeding apparatus.

FIG. 7 is a timing chart of a sheet feeding operation of the sheet feeding apparatus.

FIG. 8 is a diagram illustrating a configuration of a feeding unit of a conventional sheet feeding apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 document 1a top document 1A image reading device 1B sheet feeding device 2 vacuum suction feeding device 9 static pressure detection device 12 storage tray 13 tray motor 17 transport document detection sensor 19 suction valve 25 control device

Claims (6)

[Claims] A storage member capable of stacking and storing sheets and moving up and down; and a vacuum storage member disposed above or below the storage member and sucking the sheets stored in the storage member that has risen or lowered. A vacuum suction paper feeding means for conveying in the paper feeding direction; a static suction pressure detecting means for detecting a static suction pressure of the vacuum suction paper feeding means; and a vacuum suction based on static pressure information from the static suction pressure detecting means. A sheet feeding device, comprising: a control unit for setting a sheet feeding timing of the sheet feeding unit. 2. The control device according to claim 1, wherein the control unit determines that the sheet is attracted to the vacuum suction feeding unit when the static pressure becomes equal to or higher than a predetermined pressure based on the static pressure information, and starts a sheet conveying operation. 2. The sheet feeding apparatus according to claim 1, wherein said vacuum suction sheet feeding means is controlled. 3. The apparatus according to claim 2, wherein said control means controls said vacuum suction sheet feeding means so as to start sheet conveyance after a predetermined time has elapsed since said static pressure became equal to or higher than a predetermined pressure. 2. The sheet feeding device according to 2. 4. A lift unit for raising and lowering the storage member, wherein the control unit detects another predetermined pressure lower than the predetermined pressure before the suction static pressure detection unit detects the predetermined pressure. 3. The sheet feeding apparatus according to claim 2, wherein the driving of the lifting / lowering means is controlled so that the speed of raising the storage member is lower than the speed before the other predetermined pressure is reached. 5. The control means determines that the sheet has been attracted to the vacuum suction sheet feeding means when the static pressure rise amount in a predetermined time period is equal to or more than a predetermined amount based on the static pressure information, and 2. A sheet feeding apparatus according to claim 1, wherein said vacuum suction sheet feeding means is controlled so as to start a conveying operation. 6. An image reading apparatus comprising a sheet feeding device and an image reading section, wherein the sheet feeding device is the one according to any one of claims 1 to 5. apparatus.