JPH05116810A - Automatic sheet feeder - Google Patents

Abstract

(57) [Abstract] [Purpose] The feeding force is changed depending on the first sheet of the stacked sheets and other sheets to prevent double feeding due to an excessive feeding force, and to automatically feed sheets in a stable feeding state. Provide the device. [Configuration] A guide on which a sheet is placed, a sensor that detects that the sheet is set on the guide, a sheet feeding roller that abuts the sheet set on the guide and conveys the sheet to a predetermined position, An automatic sheet feeding device having a sheet feeding roller for feeding out a sheet and a separation roller for separating the sheet is provided with a means for detecting that the sheet is set in the guide, and determines the presence or absence of the sheet on the guide. However, a means for varying the rotation speed of the paper feed roller is provided, and the rotation speed of the paper feed roller at the time of feeding the first sheet after setting the sheet is set to be smaller than the rotation speed at the time of feeding the second and subsequent sheets. Also reduce.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic sheet feeding apparatus applied to an image forming apparatus or an image reading apparatus such as a laser printer, a copying machine and a facsimile.

[0002]

2. Description of the Related Art For example, in a sheet feeding apparatus that conveys sheets to a main body of an image forming apparatus, conventionally, as shown in FIG. 6, a sheet feeding roller 6 provided in contact with a back surface of sheets in a stacked state is provided. By rotating, the sheet is conveyed to the nip portion between the separation roller 7a and the sheet feeding roller 7b.

The conveying force to the nip portion is given by the point A which is the first contact point between the paper feed roller 6 and the sheet 23 and the outer circumference of the roller 6 shown in FIG. That is, as the peripheral speed at the point A becomes faster or the loop height h from the bottom plate 22 to the point A becomes larger, the carrying force becomes larger. When the conveying force exceeds a certain level, the lower sheet is conveyed to the nip portion against the friction between the stacked sheets.

[0004]

However, when the conveying force is further increased, the collision force to the nip portion is increased, and a plurality of sheets are stuck in the nip portion without being separated, and double feeding occurs, and a sheet feeding failure occurs. It can cause jams and jams.

As shown in FIG. 8, there is a case where the shape of the pick roller is changed from the D shape to an oval shape, but if the dimension of h is the same, the conveyance force is less deteriorated and the occurrence of double feeding is reduced. The effect is poor.

In order to prevent the occurrence of double feed, Japanese Patent Laid-Open No. 1-22
Japanese Patent No. 20649 proposes that an outer circumference of a sheet feeding rotary member that comes into contact with a sheet that is a recording sheet and feeds the sheet is composed of two arc portions having different diameters.

The present inventor has found that the occurrence of double feeding as described above is
Focusing on the fact that the first sheet is often set after the sheet is set, a structure different from that of the above publication realizes the reduction of double feed. At the time of sheet setting, as shown in FIG. 9, the top of the sheet 23 is protruded forward as shown in FIG. 9, or as shown in FIG. However, if a large carrying force is applied, separation failure may occur and double feeding may occur. On the other hand, after feeding one sheet, as shown in FIG. 11, the leading edge of the sheet is adjusted along the outer periphery of the separation roller 7a, so that it is considered that the subsequent separation is facilitated.

Therefore, according to the present invention, the conveying force is changed depending on the first and first sheets of the stacked sheets,
An object of the present invention is to provide a sheet automatic feeding device that prevents a double feed due to an excessive conveyance force and stabilizes the conveyance state.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a guide on which a sheet is placed, a sensor for detecting that the sheet is set on the guide, and a sheet set on the guide by abutting the sheet are predetermined. In a sheet automatic feeding device having a sheet feeding roller for conveying to a position, a sheet feeding roller for feeding the sheet, and a separation roller for separating the sheet, a means for detecting that the sheet is set in the guide is provided. It is provided with a means for determining the presence or absence of the sheet on the guide and varying the rotation speed of the paper feed roller. The rotation speed of the paper feed roller at the time of feeding the first sheet after setting the sheet is set to the second sheet. The above problem was solved by reducing the rotation speed during the subsequent feeding.

It is preferable to provide a non-feed detecting unit at the time of feeding the sheet, and when the non-feed of the sheet is detected by the unit, the rotation speed of the paper feed roller is increased to restart the roller. Is.

A guide for placing the sheet, a plurality of sheet feeding rollers for abutting the sheet set on the guide to convey the sheet to a predetermined position, a sheet feeding roller for feeding the sheet, and a sheet for separating the sheet. In the automatic sheet feeding device having the separation roller of the above, a means for detecting that the sheet is set in the guide is provided, the presence or absence of the sheet on the guide is determined, and a plurality of sheet feeding rollers can be separately driven. Even if only a part of the sheet feeding roller is driven at the time of feeding the first sheet after the sheet is set, the above problem can be solved.

A sheet size detection unit is provided, and when the sheet size detected by the unit is larger than a predetermined size, or according to the sheet size detected by the unit, the sheet feeding speed of the first sheet after the sheet setting. Is preferably reduced.

Further, a set sheet amount detecting means is provided, and when the sheet amount detected by the means exceeds a predetermined amount, or in accordance with the sheet amount detected by the means, 1 after the sheet setting is performed. It is more preferable to reduce the feeding speed of the first sheet.

In order to separate the guide on which the sheet is placed, a plurality of paper feed rollers for abutting the sheet set on the guide to convey the sheet to a predetermined position, a paper feed roller for feeding the sheet, and the sheet. In an automatic sheet feeding device having a separation roller, the feeding roller is formed into a cam shape so that the peripheral speed at the contact position with the sheet during one rotation of the feeding roller is gradually increased. However, the above problem is solved.

It is preferable that the rotational speed of the first sheet feeding roller after the sheet is set is gradually accelerated from low speed to high speed.

If the sheet to be fed is a document,
It is also convenient to drive the paper feed roller for a minute time while waiting for reading the first sheet after setting the original.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described based on the embodiments shown in the drawings.

1 and 2 show an example of the configuration of an image reading apparatus to which the present invention is applied.

In FIG. 1, an automatic document feeder (hereinafter referred to as "ADF") 2 is placed on the upper part of the main body 1 of the image reading apparatus, and the document set on the ADF 2 is pressed by a pressure plate. There is. Reference numeral 3 is a paper discharge tray.

As shown in FIG. 2, the ADF 2 includes a semi-circular sheet feeding roller 6 provided on the document placing table 5, and the roller 6 concerned.
Separation roller 7a for separating and feeding the stacked originals conveyed one by one, paper feed roller 7b, conveyance roller pair 8, 9 for guiding the separated originals, guide roller 10, guide roller 10 and conveyance roller A press plate 12 provided between the pair 9 and the contact glass 11 for pressing the original against the contact glass 11 without a gap, and a discharge roller 1
It is basically composed of 3.

The main body 1 of the image reading apparatus includes a light source 1
4, a reading unit 20 including a reflecting mirror 15, 16, 17, a lens 18, a reading unit 19 including a charge coupled device (hereinafter referred to as “CCD”), and the like.

As shown in FIG. 4, the presence / absence of a document on the mounting table is determined by detecting that the document has been set by the detection sensor S1.

In FIG. 2, the ADF 2 is in a state where the surface of the contact glass 11 of the main body 1 is closed. ADF2
After the set is detected by the detection sensor, the document loaded on the document placing table 5 is conveyed by the semicircular roller 6 to the separation roller 7a, separated and fed, and guided by the conveyance roller pair 8. It is fed between the contact glass 11 and the pressing plate 12 by the roller 10. This holding plate 1
At the reading position at 2, the reading operation of the image data by the reading unit 20 is performed on the original in a known manner.
After this reading operation, the document is conveyed by roller pair 9 and discharge roller 1.
3, the sheet is discharged to the sheet discharge tray 3 shown in FIG.

The paper feed roller 6, the separation roller 7a, and the paper feed roller 7b are driven by the same drive motor (not shown), and the paper feed roller 6 is driven by a solenoid (not shown).
Is given rotation. When the paper feed roller 6 is rotated, one rotation of the original separates the document 7a and the paper feed roller 7.
It is extended between b.

The control of the image reading device will be described.
In FIG. 3, the data read by the CCD is
It is output to an external device via an amplifier, an A / D converter, an image correction unit, and a binarization unit. A central processing unit (CPU) that controls the apparatus controls a drive motor, a solenoid, and the like based on input information from the document detection sensor S2, the document set detection sensor S1, and the like, and sequentially performs document conveyance control and reading control. To run.

As can be seen from the flowchart of FIG. 12, when a document is set on the ADF, the document set detection sensor S1 detects the set and the set document is loaded from the empty state of the document table. It is determined whether or not the state has changed, in other words, whether or not the document placing table has changed from the state without the document to the state with the document. When it is determined that there is a change from the absence of the original to the presence of the original, the flag is set in order to hold the information that the first original to be fed is the first original after the original is set. Then, when a sheet feeding command is received, the flag setting is checked, and if set, the rotation speed of the sheet feeding roller is reduced and then sheet feeding is started. If the flag is not set, it is determined that the document to be fed after the sheet feed command is the second or subsequent sheet, and the rotation speed of the sheet feed roller is set to high to perform sheet feeding.

Thus, the feeding force of the first sheet, which is likely to cause double feeding, is weakened without reducing the speed during continuous reading, and double feeding is prevented.

Further, as shown in FIG. 4, an original detection sensor S2 is provided between the pair of conveying rollers 8 and the guide rollers to check the non-feeding of the original which has been fed. That is, if the document to be fed does not reach the sensor S2 within a predetermined time after the start of feeding, it is determined that the document has not been fed. In this case, in the conventional technique, the paper feed roller 6 is restarted at the same rotation speed, and if the document still does not reach the sensor S2, control is performed to prompt the operator to reset the document. However, in the present embodiment, if the document does not reach the sensor even after the predetermined time has passed, if this is the first non-feed,
The paper feed roller is restarted after making the rotation speed faster than at the beginning. At this time, since the flag is released, unlike the first time, the sheet is fed at a high rotation speed.
As a result, the carrying force is made stronger than that of the first time, and the non-feeding due to the insufficient carrying force in the first time is prevented. If the non-feed is not the first time, control is performed to prompt the operator to reset the original.

In FIG. 12, the rotation speed of the paper feed roller is set to two stages, and the restart of the paper feed roller in the case of non-feed is performed at the same rotation speed as the original document feeding for the second and subsequent sheets. Although shown, the present invention is not limited to such an aspect, and the rotation speed can be changed in multiple stages so that when the feed failure occurs, the rotation speed can be sequentially increased.

By doing so, for a document that is likely to be double-fed, the document feeding force is weakened to prevent double feeding, and when the document feeding is difficult and the feed force is weakened, a document feeding is likely to occur. Enhances the carrying force and makes it less likely to cause non-feeding. Therefore, it is possible to more stably feed the original according to the original.

When a plurality of paper feed rollers configured to be separately driven are provided, as understood from the flowchart of FIG. 13, it is determined that the original set detection sensor S1 has changed from a state without a document to a state with a document. When the determination is made, the flag is set in order to hold the information that the first document to be fed thereafter is the first sheet after the document is set. Next, when a sheet feeding command is received, the flag setting is checked, and if set, only a part of the plurality of sheet feeding rollers is driven to start sheet feeding. If the flag is not set, it is determined that the second and subsequent sheets are fed, and all the sheet feeding rollers are driven to feed the sheets. In case of non-feed,
As can be seen in 3, all the paper feed rollers may be driven, but the number of driven paper feed rollers can be increased.

When the document size detecting means is provided, as will be understood from the flowchart of FIG. 14, when the document is set, the paper size is checked. As the method, for example, an operation panel or the like may be provided to input a size, or a position of the side fence may be read by a sensor for determination.

Further, when the original set detection sensor S1 determines that the original has changed from the state without the original to the state with the original, the information that the first original to be fed is the first original after the original is set is held. Then, the flag is set. Next, when the paper feed command is received, the flag set is checked, and if it is set, the rotation speed of the paper feed roller is selected according to the checked document size. Original size s
Is larger than the predetermined size S, the rotation speed of the paper feed roller is reduced to start feeding. When the flag is not set or when the original is smaller than or equal to the predetermined size S, the rotation speed is set to a high speed and the paper is fed.

FIG. 14 shows that the rotation speed of the paper feed roller is set in two stages, and the rotation speed of the paper feed roller is selected by comparison with only one predetermined size. However, the rotation speed of the first sheet feeding roller after the document is set can be changed in multiple stages, and the rotation speed can be selected according to the sheet size detected by the document size detection means. It is possible that In addition, multiple feeding rollers can be driven separately,
The number of paper feed rollers to be driven may be adjusted.

When the set original amount detecting means is provided, as understood from the flow chart of FIG. 15, when the original is set, the original amount is checked. As the method, for example, as shown in FIG. 4, a method in which a plurality of document set detection sensors S1 are provided and the amount of the document is determined can be considered.

Further, when the sensor S1 determines that the original has changed from the state without the original to the state with the original, the flag is held in order to hold the information that the first original to be fed is the first sheet after the original is set. Is set. Next, when the paper feed command is received, the flag set is checked, and if it is set, the rotation speed of the paper feed roller is selected according to the checked original amount. When the original amount h is larger than the predetermined amount H, the rotation speed of the paper feed roller is set to a low speed to start feeding. When the flag is not set, or when the original is less than or equal to the predetermined amount H, the rotation speed is set high and the paper is fed.

FIG. 15 shows that the rotation speed of the paper feed roller is set in two stages, and the rotation speed of the paper feed roller is selected by comparison with only one predetermined amount. However, the rotation speed of the first sheet feeding roller after the document is set can be changed in multiple stages, and the rotation speed can be selected according to the document amount detected by the document amount detection means. It is possible that It is also possible to separately drive a plurality of paper feed rollers and adjust the number of paper feed rollers to be driven.

By doing so, it is possible to cope with a situation in which the larger the amount of documents is, the more the frictional force between the documents is increased, and the double feeding is likely to occur.

The paper feed roller may be shaped, for example, according to the cam diagram shown in FIG. When the amount of the paper feed roller protruding from the lower guide plate is set to be gradually increased in one rotation, the peripheral speed of the roller at the contact position with the document is gradually increased, and the document conveyance force is increased. It is possible to avoid sudden growth. The gradient of the diameter increase with respect to the rotation angle of the paper feed roller should be as small as possible.

In the case of the first sheet after setting the original, the rotation speed of the paper feed roller may be gradually increased from low speed to high speed during one rotation. In this case, as understood from the flowchart of FIG. 16, the document set detection sensor S1
However, if it is determined that there is a change from the absence of the original to the presence of the original, the flag is set in order to hold the information that the original to be fed first is the first original after the original is set. Then, when a sheet feeding command is received, the flag setting is checked, and if set, the rotation speed of the sheet feeding roller is gradually increased to start sheet feeding. If the flag is not set, it is determined that the second and subsequent sheets have been fed, and the sheet is fed at a high rotation speed.

As a result, the feeding force of the first sheet, which is apt to cause the double feeding, is weakened without lowering the continuous feeding speed, and the double feeding is prevented.

The paper feed roller may be driven for a very short time during the standby for reading the first sheet after setting the original. In this case, as can be understood from the flowchart of FIG. 17, when the document set detection sensor S1 determines that the document has changed from the state without a document to the state with a document, the paper feed roller is driven at a low speed for a minute time. When it receives a paper feed command, it feeds paper.

[0043]

In the automatic sheet feeding device according to the first aspect of the present invention, since the rotation speed of the sheet feeding roller is reduced only for the first sheet of the sheet set, the double feeding of sheets is performed without changing the continuous feeding time of a plurality of sheets. Can be prevented.

In the automatic sheet feeding device of the second aspect, when the sheet feeding failure occurs, the rotation speed of the sheet feeding roller is increased when the sheet feeding roller is rotated again. Can be prevented.

In the automatic sheet feeder according to the third aspect, since only a part of the sheet feeding rollers is driven for the first sheet of the sheet set, the sheet conveying force is reduced and the plural sheets are continuously fed. Double feeding of sheets can be prevented without changing the time.

Double feeding during sheet feeding is more likely to occur because the frictional force between the sheets increases as the sheet size increases. However, in the automatic sheet feeding apparatus according to the fourth aspect, depending on the sheet size. Since the rotation speed of the paper feed roller is variable, the carrying force can be adjusted more accurately, double feeding and non-feeding can be prevented, and stable feeding can be performed.

In the automatic sheet feeder according to the fifth aspect, when the number of sheets is large, the rotation speed of the sheet feeding roller of the first sheet of the sheet set can be decreased and the conveying force can be adjusted more accurately. Also, non-feeding can be prevented, and stable feeding is performed.

In the automatic sheet feeder according to the sixth aspect, since the diameter of the sheet feed roller gradually increases, the sheet conveying force does not suddenly increase, and the double feeding of sheets can be prevented.

In the sheet automatic feeding device of the seventh aspect, since the rotation speed of the sheet feeding roller gradually increases, the sheet conveying force does not suddenly increase and the double feeding of sheets can be prevented.

In the automatic sheet feeder according to the eighth aspect of the invention, since the sheet feeding roller is driven for a minute time when the document is inserted, the leading edge of the sheet is along the surface of the separating roller as shown in FIG. Even if you rotate the paper roller at high speed,
The occurrence of double feeding can be suppressed.

[Brief description of drawings]

FIG. 1 is a perspective view of an image reading apparatus to which the present invention is applied.

FIG. 2 is a schematic end view of the image reading apparatus in FIG.

FIG. 3 is a control block diagram of an image reading apparatus including a feeding device according to an embodiment of the present invention.

FIG. 4 is a schematic end view of the feeding device according to the embodiment of the present invention.

FIG. 5 is a cam diagram showing the shape of a paper feed roller according to another embodiment of the present invention.

FIG. 6 is a schematic sectional view of a known sheet feeding device.

7 is an enlarged schematic view of a paper feed roller area of the apparatus of FIG.

FIG. 8 is a schematic view of a paper feed roller having a shape different from that of FIG.

FIG. 9 is a schematic cross-sectional view of the feeding device with sheets stacked.

FIG. 10 is a schematic cross-sectional view of a sheet feeding device in which sheets are stacked in a state different from that in FIG.

FIG. 11 is a conceptual diagram showing a state of stacked sheets after one sheet is fed.

FIG. 12 is an operation flowchart of the feeding device according to the embodiment of the present invention.

FIG. 13 is an operation flowchart of a feeding device according to another embodiment of the present invention.

FIG. 14 is an operation flowchart of a feeding device improved from that of FIG. 12;

FIG. 15 is an operation flowchart of the feeding device improved from that of FIG. 12;

16 is an operational flowchart of a feeding device improved from that of FIG. 12;

FIG. 17 is an operation flowchart of the feeding device improved from that of FIG. 12;

[Explanation of symbols]

 6 Paper feed roller 7a Separation roller S1 Original set detection sensor S2 Original detection sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location G03G 15/00 107 8530-2H 110 7369-2H H04N 1/00 108 L 4226-5C

Claims (8)

[Claims] 1. A guide for placing a sheet, a sheet feeding roller for abutting the sheet set on the guide and conveying the sheet to a predetermined position, a sheet feeding roller for feeding the sheet, and a sheet for separating the sheet. In the sheet automatic feeding device having the separation roller of the above, a means for detecting that the sheet is set in the guide is provided, the presence or absence of the sheet on the guide is determined, and the rotation speed of the paper feeding roller is made variable. Means for automatically feeding the sheet after the sheet is set to reduce the rotational speed of the sheet feeding roller at the time of feeding the second sheet and thereafter. apparatus. 2. A non-feed detecting unit at the time of sheet feeding,
2. The automatic sheet feeding device according to claim 1, wherein when the feeding failure of the sheet is detected by the means, the rotation speed of the paper feed roller is increased and the roller is restarted. 3. A guide on which a sheet is placed, a plurality of paper feed rollers that contact the sheet set on the guide and convey the sheet to a predetermined position, a paper feed roller that feeds the sheet, and a sheet that separates the sheet. In a sheet automatic feeding device having a separation roller for carrying out, a means for detecting that a sheet is set in the guide is provided, the presence or absence of the sheet on the guide is determined, and the plurality of sheet feeding rollers are individually separated. An automatic sheet feeding device, which is configured to be drivable and drives only a part of the sheet feeding roller at the time of feeding the first sheet after setting a sheet. 4. A sheet size detecting means is provided, and when the sheet size detected by the means is larger than a predetermined size, or according to the sheet size detected by the means, the first sheet after the sheet setting is fed. The automatic sheet feeder according to claim 1 or 3, wherein the sheet speed is reduced. 5. A set sheet amount detecting means is provided,
When the sheet amount detected by the means exceeds a predetermined amount, or in accordance with the sheet amount detected by the means, the feeding speed of the first sheet after the sheet setting is reduced. The automatic sheet feeder according to claim 1 or 3. 6. A guide on which a sheet is placed, a plurality of sheet feeding rollers that abut the sheet set on the guide and convey the sheet to a predetermined position, a sheet feeding roller that feeds the sheet, and a sheet that separates the sheet. In a sheet automatic feeding device having a separation roller for performing the above, the peripheral shape of the sheet feeding roller is gradually increased at a contact position with the sheet during one rotation of the sheet feeding roller. An automatic sheet feeding device characterized by the above. 7. The method according to claim 1, wherein the rotational speed of the first sheet feeding roller after the sheet is set is gradually accelerated from low speed to high speed. Sheet automatic feeding device. 8. The sheet feeding roller according to claim 1, wherein the sheet feeding roller is driven for a minute time while waiting for reading the first sheet after the sheet is set. Automatic sheet feeding device.