JPH1111718A - Paper feeder and image forming apparatus - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable stable sheet feeding while suppressing fluttering of sheets. SOLUTION: A control device determines whether or not a document 1 is fluttering based on signals input from a leading edge fluttering detecting sensor 28 and a trailing edge fluttering detecting sensor 32,
If it is determined that the document 1 is fluttering, the valve 23 is controlled to adjust the amount of air blown from the separating device 6 onto the document 1 so as to reduce the fluttering of the document 1 and perform stable paper feeding. be able to.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeder and an image forming apparatus for blowing the air to separate the lowermost or uppermost sheet of a sheet such as a document and conveying the separated sheet.

[0002]

2. Description of the Related Art As a paper feeder which is provided above an image forming apparatus such as a copying machine and conveys a document on a platen glass,
For example, there is a sheet feeding device that blows air from the leading end side of a document bundle to separate the lowermost or uppermost document of the document bundle, and sucks and transports one separated document.

FIG. 10 is a schematic sectional view showing an example of the above-mentioned conventional paper feeder.

In this paper feeder 100, a notch (not shown) is provided at the center of a front portion of a document tray 2 on which a plurality of documents 1 are stacked, and a number of holes (not shown) are formed in the notch. The provided rubber belt 3 is stretched and installed by a driving roller 4a and a driven roller 4b. A vacuum box 5 is provided inside the rubber belt 3.
When the air (air) is sucked from a hole provided in the rubber belt 3 by a blower (not shown) connected to the camera, the lowermost document 1 is sucked, and the rotation of the rubber belt 3 by the driving of the driving roller 4a causes the suction. The lowermost document 1 is sent out in the transport direction.

[0005] A separating device 6 is provided above the tip of the rubber belt 3. A large number of outlets 6a for blowing air obliquely downward are provided in the separating device 6, and between the lowermost original taken out by the rubber belt 3 from these outlets 6a and the original thereon. By blowing air, only the lowermost document is separated and sent out.

The lowermost document separated by one sheet in this manner is conveyed to a predetermined position on a document table glass 9 by conveyance rollers 7 and a document belt 8. Then, after the image of the document is read by the exposure device 11 of the image forming apparatus main body (copier main body) 10, the document is discharged by the transport rollers 12 and 13 and the discharge roller 14.
The discharged document abuts against a document abutting plate 15 which is an elastic member such as rubber and falls, and is stacked again on the document 1 stacked on the document tray 2.

In FIG. 10, reference numeral 16 denotes a regulating plate which is stacked on the original tray 2 and regulates the width of the original 1;
Reference numeral denotes a trailing edge regulating plate that regulates the trailing edge of the document 1.

[0008]

By the way, in the above-mentioned conventional paper feeding apparatus 100, regardless of whether the number of the originals 1 stacked on the original tray 2 is small or large, the originals 1 are discharged from the outlet 6a of the separation device 6. Since the volume of the blown air (hereinafter, referred to as separation air) is constant, there are the following problems.

(A) Original document 1 of maximum size is placed on original tray 2
When a large number of sheets are stacked on the upper side, the above-described separation air is set to the maximum air volume capable of feeding the lowermost document 1,
When the number of the originals 1 was small, the originals 1 fluttered on the original tray 2, and stable feeding could not be performed.

(B) It is difficult to prevent the original 1 from fluttering according to the paper condition of the original 1, for example, the thickness of the paper and the degree of moisture absorption.

(C) Japanese Patent No. 2502394 proposes detecting the floating amount of the document 1 floating above the document tray 2 by the separating air and adjusting the air flow of the separating air so as to keep the floating amount at a predetermined amount. However, in this proposal, in order to control the floating amount of the document 1 to a predetermined amount, it is determined that the sheet can be fed even when the document 1 flies due to the separation air. Therefore, there was a case where stable paper feeding could not be performed.

Accordingly, the present invention provides a sheet feeding apparatus and an image forming apparatus capable of preventing a sheet from fluttering and performing stable sheet feeding regardless of the state, size, and stacking amount of sheets such as originals. The purpose is to:

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has a structure in which a plurality of sheets can be stacked and a sheet stacked in the stacking means is provided. In a paper feeder, comprising: a separating unit that separates from another sheet by blowing air from a leading end side; and a conveying unit that conveys the sheets separated by the separating unit one by one. Air flow rate adjusting means for adjusting the air flow rate of the air, sheet fluttering detecting means for detecting fluttering of the sheet caused by blowing the air to the leading end side of the sheet stacked on the stacking means, A signal output according to the sheet flutter is input from the sheet flutter detection means, and the air flow rate adjusting means is controlled based on the input signal to control the air flow rate. It is characterized by comprising a control means for adjusting the air volume of A, the.

The control means determines whether or not the sheet is fluttering based on the input signal, and if the sheet is determined to flutter, controls the air flow rate adjusting means. And adjusting the amount of air blown from the separation unit to the sheet so as to be reduced.

[0015] The sheet fluttering detecting means may include a swinging member supported so as to be swingable and having a leading end abutting on the sheet loaded on the stacking means, and a swinging member of the sheet swinging due to the sheet fluttering. Detecting means for detecting a flutter cycle of the sheet from movement.

The control means compares the fluttering cycle of the sheet input from the sheet fluttering detecting means with a preset fluttering cycle, and determines whether the input fluttering cycle of the sheet is equal to the set fluttering cycle. If it is less than the cycle, it is determined that the sheet is fluttering, and the sheet flapping cycle is determined from the maximum air volume of the air capable of separating the maximum number of sheets in the maximum size of the sheets stacked on the stacking unit. Is characterized by controlling the air flow rate adjusting means so as to gradually reduce the flow rate of the air until the fluttering cycle becomes equal to or longer than the set flutter cycle.

Further, the sheet fluttering detecting means detects fluttering of the sheet leading end and / or the sheet trailing end.

In the image forming apparatus according to the present invention, a sheet having image information is fed to a reading unit.
5. A sheet feeding device according to claim 1, further comprising: an image forming unit configured to form image information of the sheet read by the reading unit on a transfer material.

(Operation) According to the structure of the present invention, the control means inputs a signal output according to the fluttering of the sheet from the fluttering detecting means, and determines whether or not the sheet is fluttering. If it is determined that the sheet is fluttering, the air flow amount adjusting means is controlled to adjust the air flow from the separating means so as to reduce the amount of air blown onto the sheet. it can.

[0020]

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

FIG. 1 shows an image forming apparatus (copier) provided with a sheet feeding device according to the present embodiment. Note that members having the same functions as those of the above-described conventional example are denoted by the same reference numerals, and redundant description will be omitted.

In the sheet feeding device 20 shown in FIG. 1, a valve 23 for adjusting the air supply amount is provided in a flow path 22 between the separation device 6 and a blower 21 for supplying air to the separation device 6. I have. The valve 23 changes the angle according to the rotation angle of a stepping motor (see FIG. 4) 25 connected to the shaft 24 and adjusts the opening area, thereby reducing the amount of air blown out from the outlet 6 a of the separation device 6. It can be controlled (details will be described later).

As shown in FIGS. 2 and 3, the rubber belt 3 is provided with a suction sensor 26, a sensor flag 27, and a fluttering sensor 28. FIG. 2 shows a state before the lowermost original of the originals 1 stacked on the original tray 2 is adsorbed on the rubber belt 3.
Indicates a state in which the lowermost original 1 a of the original 1 is adsorbed on the rubber belt 3.

The suction detection sensor 26 is composed of a pair of photocouplers. When the sensor flag 27 blocks light between the pair of suction detection sensors (photocouplers) 26, as shown in FIG. Equipment (CP
U) 29, and the control device 29 detects, based on the input signal, that the lowermost original 1a of the originals 1 stacked on the original tray 2 is attracted to the rubber belt 3.

As shown in FIG. 5, the sensor flag 27 is urged by an urging means (not shown), and its tip protrudes from between the rubber belts 3, and the original 1 is stacked on the original tray 2. At this time, when the lowermost document 1a separated on the rubber belt 3 is sucked by the vacuum box 5, it is pushed down and shields the space between the pair of suction detection sensors (photocouplers) 26 from light.

One end of the sensor flag 27 is rotatably supported by a shaft 30. A light pressure torsion coil spring 31 for applying a clockwise rotational urging force to the sensor flag 27 is wound around the shaft 30. It is attached. The sensor flag 27 is provided with a stopper (not shown). When the document 1 is not stacked on the document tray 2 by the stopper, the sensor flag 27
Stop above the levitation position.

The tip flapping detection sensor 28 is a pair of photocouplers configured to be shielded from light by the sensor flag 27 at an appropriate flying height or less and pass at a height higher than the appropriate flying height. When the sensor flag 27 blocks light between the photocouplers 28, as shown in FIG.
U) 29, and the control device 29 detects the fluttering of the front end side of the original 1 placed on the original tray 2 by the air blown out from the outlet 6a of the separation device 6 based on the input signal. .

As shown in FIGS. 6 and 7, a rear end of the document tray 2 is provided with a pair of photocouplers for detecting fluttering of the rear end of the document 1 as shown in FIGS. A fluttering detection sensor 32 is provided, and the trailing edge regulating plate 17 and the trailing edge fluttering detection sensor 32 are connected to the document tray 2 according to the size of the document 1 stacked on the document tray 2.
In the front-rear direction (arrow a direction).

A disc-shaped detection plate 34 rotatably supported by a shaft 33 is provided between a pair of rear end fluttering detection sensors (a pair of photocouplers) 32.
Is connected to a stepping motor 36 for rotating the lever 35 and the detection plate 34. A protruding light shielding portion 34a is formed on the outer peripheral surface of the detection plate 34, and a number of holes 34b are formed on the circumference of the detection plate 34. When the trailing edge of the original 1 flaps, the trailing
5 swings, and the hole 34 of the detection plate 34 swings with the swing.
As shown in FIG. 4, by the passage and blocking of light by b,
The ON / OFF signal due to the passage and blocking of light is transmitted to the control unit (C
PU) 29, and the control device 29 detects the fluttering of the rear end of the document 1 based on the input signal.

On both sides of the detection plate 34, a lever position sensor 37 composed of a pair of photocouplers is provided.

FIGS. 8 and 9 show a state in which the original 1 is not placed on the original tray 2 (this state is the home position). The light-shielding portion 34a of the plate 34 shields the pair of lever position sensors 37 from light. A light-shielding portion 34 of a detection plate 34 is provided between a pair of lever position sensors (photocouplers) 37.
When a is shielded, as shown in FIG. 4, a signal at the time of shielding is input to the control device (CPU) 29, and the control device 29 detects the position of the lever 35 based on the input signal.

In FIG. 1, an image forming apparatus main body (copier main body) 10 provided with a paper feeding device 20 at an upper portion includes an exposure device 11, an image forming unit 12, and the like.

Next, the operation of the above-described paper feeding device 20 will be described.

First, the original 1 is stacked on the original tray 2,
When a start button (not shown) on the side of the image forming apparatus (copier body) 11 is pressed, air is supplied from the blower 21 to the separation apparatus 6 through the flow path 22, and the air is supplied from the outlet 6 a of the separation apparatus 6 onto the document tray 2. Separation air is blown to the leading edge of the document 1 to float the document 1.

At this time, as shown in FIG. 4, a signal is output from the control device (CPU) 29 to the driver 39, the stepping motor 25 is driven to open the valve 23 to the maximum, and the air volume of the separation air is maximized. Set it to appear.
At this time, the air volume of the separation air is set to an air volume capable of separating the maximum size of the document 1 and the maximum number of stacked sheets.

At the maximum air volume of the separation air, it is determined whether the leading edge and the trailing edge of the document 1 are fluttering.
To detect.

That is, as shown in FIGS. 2 and 3, the fluttering detection sensor 28 repeats ON / OFF by swinging of the sensor flag 27 which comes into contact with the lowermost document 1a due to the fluttering of the leading edge of the document 1. (CPU)
Reference numeral 29 inputs the signal of the repetition cycle and measures the repetition cycle to detect the fluttering of the leading edge of the document 1 (floating more than appropriate) (the fluttering cycle of the leading edge).

When the originals 1 are stacked on the original tray 2 from the home position shown in FIGS. 8 and 9, as shown in FIG.
PU) 29, and a signal is inputted to the control device (CPU) 29.
Outputs a signal to the driver 38 to drive the stepping motor 36 to move the lever 35 from the home position by about 1 degree.
Rotate counterclockwise by 80 degrees. And then, FIG.
As shown in FIG. 7, the lever 35 moves the detection plate 34 by its own weight.
And the leading end of the lever 35 contacts the upper surface of the rear end of the document 1.

When the trailing edge of the original 1 flaps, the lever 35 swings, and the detection plate 34 swings at the same time. The rear end fluttering detection sensor 32 repeats ON / OFF by a large number of holes 34a formed in the circumferential direction of the detection plate 34, and the control device (CPU) 29 inputs a signal of this repetition cycle and By measuring the period, the fluttering of the rear end of the document 1 is detected (rear fluttering period).

When the control unit (CPU) 29 determines that the measured leading edge fluttering cycle or trailing edge fluttering cycle is equal to or less than a preset fluttering cycle, it determines that the document 1 is fluttering. I do. On this occasion,
If it is determined that the document 1 is fluttering, the control device (CPU) 29 outputs a signal to the driver 39 and drives the stepping motor 25 to change the angle of the valve 23, thereby reducing the air volume of the separation air. Lower by a predetermined amount (for example, one step).

In this state, the leading and trailing flutter cycles are measured again in the same manner as described above, and it is determined whether or not the flutter cycle is equal to or less than the set flutter cycle. This sequence is repeated, and when the control device (CPU) 29 determines that the leading edge fluttering cycle and the trailing edge fluttering cycle of the document 1 have become equal to or longer than the set fluttering cycle, it is determined that the fluttering of the document 1 has fallen below the set fluttering cycle. Then, the separation air having the air volume at this time is blown to the front end of the document 1.

At this time, air is sucked from a hole (not shown) provided in the rubber belt 3 by a blower (not shown) connected to the vacuum box 5, and the lowermost original 1 a is sucked onto the rubber belt 3 to be finally sucked. Lower original 1a is replaced with other original 1
The document is conveyed by the rubber belt 3 and conveyed to a predetermined position on the document table glass 9 by the conveyance roller 7 and the document belt 8. Then, the image forming apparatus main body (copier main body) 1
The image of the document is read by the exposure device 11 of 0, and a copy image is formed by the image forming unit 12.

As described above, in the present embodiment, the fluttering of the leading edge and the trailing edge of the original 1 is detected by the leading edge fluttering detecting sensor 28 and the trailing edge fluttering detecting sensor 32, and the air (separation) blown to the leading edge side of the original 1 is detected. The amount of air (air) can be controlled by the control unit (CPU) 29 so that the leading edge and the trailing edge of the document 1 do not flutter, so that the size and number of documents 1 loaded on the document tray 2 and the number of documents The original 1 can be stably fed regardless of the state of the original 1 (for example, curl, moisture absorption, etc.).

Also, since the fluttering of the original 1 can be suppressed, the lowermost original 1
a to the rubber belt 3 (vacuum box 5
Is reduced to a negative pressure, and the variation in the time from when suction of the floating document 1 is started to when a suction signal is input from the suction detection sensor 26 to the control device (CPU) 29) can be suppressed. The time required for paper feeding can be stabilized.

Further, since the fluttering of the original 1 can be suppressed, the original 1 is transported onto the original
The original 1 discharged above can be stably stacked again without causing a shift, and can be stably fed even when the original 1 is circulated again and fed.

Further, the amount of separation air blown out from the outlet 6a of the separation device 6 can be adjusted according to the size of the document 1 and the number of sheets to be placed, so that the separation air does not become excessive. In addition, it is possible to reduce the noise of the blower 21 and to save power, and it is possible to reduce the sound of the original 1 that rattles on the original tray 2 due to the rattling of the original 1.

In the above embodiment, the opening and closing of the valve 23 is adjusted stepwise by the stepping motor 25. However, the valve 23 is driven by a solenoid or the like to adjust the flow rate of the separation air. It may be. At this time, the number of switching stages of the air volume of the separation air is at least three, and it is preferable that the number of switching stages is large.

In the above embodiment, the opening and closing of the valve 23 is adjusted stepwise by the stepping motor 25. However, the valve 23 is driven by driving the stepping motor 25 in accordance with the above-mentioned tip variation cycle. May be opened and closed steplessly to adjust the flow rate of the separation air.

[0049]

As described above, according to the present invention, when the sheet is fluttering, the air flow amount adjusting means is controlled so as to reduce the amount of air blown from the separating means onto the sheet. Since the fluttering of the sheets can be suppressed, the deviation of the sheet bundle due to the fluttering of the sheets can be prevented, and the accompanying double feed and skew feed can be eliminated, thereby enabling stable feeding.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an image forming apparatus provided with a sheet feeding device according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing the vicinity of a leading end of a document of the sheet feeding device according to the embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view showing the vicinity of a leading end of a document of the sheet feeding device according to the embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a control system of the sheet feeding device according to the embodiment of the present invention.

FIG. 5 is a perspective view showing a leading end side of the sheet feeding device according to the embodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view showing the vicinity of the rear end of a document in the sheet feeding device according to the embodiment of the present invention.

FIG. 7 is a plan view of FIG. 6;

FIG. 8 is an enlarged cross-sectional view showing the vicinity of a rear end of a document in the sheet feeding device according to the embodiment of the present invention.

FIG. 9 is a plan view of FIG. 8;

FIG. 10 is a schematic cross-sectional view showing a sheet feeding device according to a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Original 1a Lowermost original 2 Original tray 3 Rubber belt (conveying means) 5 Vacuum box 6 Separating device (separating means) 6a Blow-out port 9 Platen glass 10 Image forming apparatus main body 20 Paper feeder 21 Blower 23 Valve (air flow rate adjustment) Means) 25, 36 Stepping motor 26 Suction detection sensor 27 Sensor flag (oscillating member) 28 Tip fluttering detection sensor (Sheet fluttering detecting means) 29 Controller (Control means) 32 Rear end fluttering detecting sensor (Sheet fluttering detecting means) 34 Detection plate 35 Lever (swinging member) 37 Lever position sensor

Claims (6)

[Claims] A stacking unit capable of stacking a plurality of sheets, a separating unit configured to separate the sheets stacked on the stacking unit from other sheets by blowing air from a leading end side of the sheets; A sheet feeding device comprising: a conveying unit configured to convey the sheets separated by the separating unit one by one; an air flow adjusting unit configured to adjust an air flow of the air ejected from the separating unit; Sheet flutter detecting means for detecting flutter of the sheet caused by spraying on the leading end side of the sheets stacked on the stacking means; and inputting a signal output from the sheet flutter detecting means in accordance with the flutter of the sheet. Control means for controlling the air flow rate adjusting means based on the input signal to adjust the air flow rate of the air. Paper equipment. 2. The control unit determines whether the sheet is fluttering based on the input signal,
2. The supply according to claim 1, wherein, when it is determined that the sheet is fluttering, the air flow amount adjusting means is controlled to reduce the air flow rate of the air blown from the separation means onto the sheet. Paper equipment. 3. The sheet fluttering detecting means includes a swinging member which is swingably supported and whose leading end is in contact with the sheet loaded on the stacking means, and a swinging member which swings due to the sheet fluttering. The sheet feeding device according to claim 1, further comprising: a detection unit configured to detect a flutter cycle of the sheet from movement. 4. The control means compares a fluttering cycle of the sheet input from the sheet fluttering detecting means with a preset fluttering cycle, and sets the fluttering cycle of the input sheet to the set fluttering cycle. If it is less than the cycle, it is determined that the sheet is fluttering, and the sheet flapping cycle is determined from the maximum air volume of the air capable of separating the maximum number of sheets in the maximum size of the sheets stacked on the stacking unit. 4. The paper feeding device according to claim 3, wherein the air flow amount adjusting means is controlled so that the air flow amount of the air is gradually reduced until the air flow exceeds the set fluttering cycle. 5. The sheet feeding device according to claim 1, wherein the sheet fluttering detecting unit detects fluttering of the sheet leading edge and / or the sheet trailing edge. 6. The sheet feeding device according to claim 1, wherein a sheet having image information is fed to a reading unit.
An image forming apparatus, comprising: an image forming unit configured to form an image on a transfer material using the image information of the sheet read by the reading unit.