JP3652483B2 - Automatic document feeder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic document feeder that is provided in an image forming apparatus such as a copying machine and feeds a set document one by one toward a document reading position.
[0002]
[Prior art]
Conventionally, as a method of separating a plurality of set originals one by one and transporting them to a reading position, the originals are separated one by one by a separation roller having a predetermined separation load means and a paper feeding roller and fed. A method (FRR method) is widely adopted.
[0003]
The separation roller and paper supply roller have their friction coefficient lowered with time or due to dirt on the document. However, if the friction coefficient falls below a certain level, double feeding or non-feeding will occur, resulting in accurate separation and feeding. Cannot be performed. Therefore, conventionally, such a problem is prevented from occurring by periodically cleaning and replacing the separation roller and the paper feeding roller.
[0004]
[Problems to be solved by the present invention]
However, the degree of decrease in the coefficient of friction of the separation roller and paper feed roller varies greatly depending on the type of document being transported and the usage environment, so it is not possible to prevent document feed defects by simply performing periodic cleaning or replacement. Have difficulty.
[0005]
The present invention has been made paying attention to the above circumstances, and the object of the present invention is to detect a decrease in the coefficient of friction of a separation element that separates documents one by one, thereby preventing document feeding failure beforehand. An object is to provide an automatic document feeder.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is an automatic document feeder that separates a set document one by one and automatically conveys it to an image reading position. A separation roller that rotates while being in pressure contact with the rotating body and separates a fed document one by one in cooperation with the rotating body, a detecting unit that detects a rotation state of the separating roller, and a rotation of the rotating body A first period measuring unit that measures a period of the first pulse signal according to the state, and the detection unit measures a period of the second pulse signal according to the rotation state of the separation roller. And a comparator that compares the cycle measured by the first cycle measuring unit with the cycle measured by the second cycle measuring unit, and the document is moved from the document setting position. Supply between the separation roller and the rotating body. The time until, and detecting the difference between the linear speed of the linear velocity and the rotation of the separation roller based on a result of comparison by the comparator.
[0007]
According to the first aspect of the present invention, the change of the friction coefficient between the separation roller and the rotating body can be detected by the detecting means, and the document feeding failure can be prevented.
[0009]
Furthermore, the change of the friction coefficient between the separation roller and the rotating body can be detected with high accuracy by the detecting means.
[0010]
According to a second aspect of the present invention, in the first aspect of the invention, the control unit is configured to control the document feeding operation based on the detection information from the detection unit, and the linear velocity difference between the separation roller and the rotating body is determined. If the set value is exceeded, the control unit stops the document feeding operation.
[0011]
According to the second aspect of the present invention, it is possible to prevent document conveyance failure by the control means.
[0012]
According to a third aspect of the present invention, in the first aspect of the invention, there is provided warning means for notifying an abnormality in a paper feed state, and when the difference in linear velocity between the separation roller and the rotating body exceeds a set value, The warning means notifies the abnormality of the paper feeding state.
[0013]
According to the third aspect of the present invention, it is possible to warn the operator of an abnormal paper feed and to perform an appropriate process for preventing a conveyance failure.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0015]
FIG. 1 shows an automatic document feeder (hereinafter simply referred to as ADF) 6 according to the present embodiment. As shown in the figure, the ADF 6 is mounted on the upper part of the copying machine 1 having an image reading device. A slit glass (reading position) 2 and a contact glass 3 are provided on the upper surface of the copying machine 1. Below the slit glass 2 and the contact glass 3, an exposure lamp 4 and a first mirror 5 are provided as image reading means. When the image reading means of the copying machine 1 reads the document P set on the contact glass 3, the exposure lamp 4 and the first mirror 5 move in the left-right direction in the figure below the contact glass 3 to move the document surface. When the original P is read through the slit glass 2, the original surface is read with the exposure lamp 4 and the first mirror 5 stopped below the slit glass 2. The image reading method in such a form is well known and will not be described in detail. However, the light reflected from the exposure lamp 4 toward the document surface is reflected by the first mirror 5. The image is sent to an imaging element such as a CCD by a lens (not shown) and imaged by this imaging element.
[0016]
On the lower surface of the ADF 6, there is provided a reflecting plate 7 that covers and presses the document P placed on the contact glass 3 and serves as a white reference when the document P is read. The ADF 6 is connected to the copying machine 1 via a hinge (not shown), and can be contacted with and separated from the upper surface of the copying machine 1.
[0017]
A document placing table 9 is provided above the ADF 6, and a document bundle composed of a plurality of documents P is set on the document placing table 9. The original P set on the original placing table 9 is sent to the separation portion D between the paper feeding belt 11 and the separation roller (separation roller) 12 when the calling roller 10 abuts on the upper surface and rotates. It has become. In the separation unit D, the paper feeding belt 11 rotates in the conveyance direction, while the original P is separated from the top by the separation roller 12 and fed. In this case, a rotational force is transmitted to the separation roller 12 via a rotational load bearing 51 such as a torque limiter from a drive shaft that rotates in the direction opposite to the conveyance direction. Thereby, the separation roller 12 rotates in the paper feeding direction when the number of originals entering the separation unit D is zero or one, and is stopped or reversed when two or more originals enter the separation unit D. It is like that.
[0018]
A stopper member 13 is provided on the downstream side of the calling roller 10 in the document conveyance direction. The stopper member 13 stops the document P placed on the document table 9 and prevents the document P from entering the paper feed belt 11 side. Further, the paper feed belt 11 is in pressure contact with the separation roller 12 at an arbitrary angle θ. Further, the separation roller 12 has a rotation detection means 50 described later.
[0019]
A push-up plate 14 is provided below the calling roller 10. The push-up plate 14 is rotated about a rotation fulcrum 14a on the upstream side in the transport direction by a solenoid (not shown), and the tip end side thereof is close to or separated from the calling roller 10. That is, when the copy start switch on the copying machine 1 side is pressed, the push-up plate 14 moves from the solid line position separated from the calling roller 10 to the one-dot chain line position close to the calling roller 10 to call the document P. The roller P is pressed against the roller 10 and the document P can be sent out by the calling roller 10.
[0020]
The sheet feeding belt 11 is wound around a driving roller 15 and a driven roller 16 and is accommodated in a case 17. The drive roller 15 is detachably attached to the main body of the ADF 6 and is attached to a shaft 15a that is rotationally driven. A one-way clutch 21 is provided between the driving roller 15 and the shaft 15a, and the driving roller 15 rotates clockwise in the drawing through the clutch 21 to drive the paper feeding belt 11.
[0021]
On the other hand, the driven roller 16 is supported while being biased by the spring 20 in a direction away from the drive roller 15. Therefore, a constant tension is applied to the sheet feeding belt 11 by the spring 20. The case 17 is supported so as to be rotatable about a shaft 15a. The calling roller 10 is attached to the case 17.
[0022]
The case 17 is positioned by being pressed by a paper supply unit cover 18 that can be opened and closed. Further, by positioning the case 17 in this manner, the paper feeding belt 11 is brought into pressure contact with the separation roller 12 and the calling roller 10 is positioned. On the other hand, when the case 17 rotates in the same direction with the shaft 15a as a fulcrum while the paper feed unit cover 18 is rotated in the opening direction, the pressing force to the original P by the calling roller 10 and the paper feed belt 11 Is released. The sheet feeding unit cover 18 is attached so as to be rotatable about a fulcrum 19.
[0023]
Drive of the shaft 15a is transmitted to the calling roller 10 via a gap clutch (not shown). The gap clutch is a member formed with a meshing portion so that the driving of the shaft 15a is transmitted to the calling roller 10 while rotating by a predetermined angle, and conversely, the calling roller 10 is fed by the original P fed by the paper feeding belt 11. The gears that transmit the drive are disengaged when they are carried around. For this reason, when the rear end of the uppermost document P is removed from the calling roller 10, the rotation of the shaft 15a is not transmitted to the calling roller 10 until it rotates by a predetermined angle, and the paper gap with the subsequent document P is opened during that time. It has become. In order to exhibit such a function, the driving roller 15 and the calling roller 10 may be driven via an electromagnetic clutch or a spring clutch instead of the gap clutch.
[0024]
The original P separated by the paper feeding belt 11 and the separation roller 12 is sent while being reversed along the reversing path 25 by the first conveying roller 23 and the driven roller 24 that are rotationally driven by a motor (not shown), and is sent to the slit glass 2. It is conveyed toward. The driven roller 24 is attached to a lever 26 that is supported so as to be rotatable about a fulcrum 19 of the sheet feeding unit cover 18. Further, the end of the lever 26 is pressed by a spring 27 attached to the sheet feeding unit cover 18 at its end. Therefore, the driven roller 24 is brought into pressure contact with the first conveying roller 23 by the urging force of the spring 27. In the figure, S is a registration sensor. When the leading edge of the document P is detected by the registration sensor S, the document P is temporarily stopped in order to synchronize the feeding timing of the document P.
[0025]
The document P transported by the first transport roller 23 and the driven roller 24 is guided by the reversing guide 28 and passed over the slit glass 2, and then guided to be scooped up by the reversing discharge guide 29, and the paper discharge path 30. Is passed through. Further, the original P passed through the paper discharge path 30 is transported (carryed out) while being sandwiched between the second transport roller 32 and the driven roller 38 and between the paper discharge roller 34 and the driven roller 35, and the charge is eliminated. After being neutralized by the brush 36, it is discharged onto the exterior cover 37.
[0026]
When the original P passes through the slit glass 2, the original image is read by the exposure lamp 4, the first mirror 5, etc. In this case, the reflection guide member provided above the slit glass 2 is used. The light from the exposure lamp 4 is reflected by 31 and the reflection guide member 31 becomes a white reference at the time of reading.
[0027]
On the other hand, the reflection plate 7 covering the contact glass 3 is provided on the lower surface of the pressure plate 38, and the pressure plate 38 presses the original P placed on the contact glass 3 against the glass 3. Yes. The pressure plate 38 is rotatably attached to the main frame 40 via a fulcrum 39.
[0028]
An end of the main frame 40 is attached to the shaft of the driven roller 35 and is fixed to the main body of the ADF 6. The main frame 40 has an area covering the contact glass 3, and constitutes a document discharge table together with an exterior cover 37 attached to the upper surface thereof.
[0029]
An auxiliary frame 42 is connected to the pressure plate 38 via a link 41. The auxiliary frame 42 has a substantially U-shaped cross section so as to sandwich the outer periphery of the main frame 40, and is rotatably connected to the main frame 40 via a fulcrum 43. The main frame 40 is provided with a magnet 44, and the magnet 44 attracts the auxiliary frame 42. The auxiliary frame 42 is entirely formed of metal, but may be formed of an elastic member such as plastic. In addition, when forming by elastic members, such as a plastic, it is necessary to form the part attracted | sucked by the magnet 44 with a metal.
[0030]
A guide plate 42a that constitutes a part of the paper discharge path 30 is formed at the distal end portion (left end portion in the drawing) of the auxiliary frame 42, and a driven roller 33 is rotatably provided on the guide plate 42a. Yes. The guide plate 42a is provided with a stamp unit 45. The stamp unit 45 is placed at a predetermined position on the downstream side in the transport direction of the document P that has passed through the slit glass 2 by causing the solenoid to protrude and retract from the guide plate 42a. A stamp is already stamped. In this way, if the stamp is stamped, it is possible to confirm the end of reading and the double feed failure of the document P.
[0031]
A handle 46 that can be gripped by the user is provided in the vicinity of the guide plate 42 a of the auxiliary frame 42. The main frame 40 is provided with a stopper 47. The stopper 47 abuts on the base end portion (right end portion in the drawing) of the auxiliary frame 42 and prevents the auxiliary frame 42 from rotating more than a predetermined amount counterclockwise around the fulcrum 43.
[0032]
FIG. 2 schematically shows a circuit diagram of a detection device for detecting the rotational state of the separation roller 12 and determining the degree of decrease in the friction coefficient of the separation roller 12. As shown in the figure, a rotary encoder 63 is attached to a drive shaft for rotating the separation roller 12, and this encoder 63 outputs a predetermined pulse signal according to the rotation state of the drive shaft. The pulse signal output from the encoder 63 is transmitted to the period measurement unit 64 and the period is measured. That is, the rotary encoder 63 and the period measuring unit 64 constitute the above-described rotation detection means 50 that converts the rotation number into a pulse signal and extracts it and processes it to detect the rotation state of the separation roller 12. .
[0033]
Reference numeral 61 in the figure denotes a paper feed motor that transmits rotational force to the shaft 15a for driving the paper feed belt 11 and the calling roller 10, and a predetermined value corresponding to the rotational state of the shaft 15a is also provided from the paper feed motor 61 side. The pulse signal is transmitted to the period measuring unit 62 and the period is measured.
[0034]
The measurement results obtained by the period measuring units 62 and 64 are sent to the comparator 65, and the comparator 65 calculates the linear velocity difference between the separation roller 12 and the paper feed belt 11. The linear velocity difference data calculated by the comparator 65 is sent to the CPU 60, and the CPU 60 controls the operation of the paper feed motor 61 based on this data. In addition, a warning display device 67 is connected to the CPU 60.
[0035]
Next, the operation of the detection device will be described together with the operation of the ADF 6.
[0036]
First, when the copy start switch on the copier 1 side is pressed, the push-up plate 14 moves from a solid line position separated from the calling roller 10 to a one-dot chain line position close to the calling roller 10. As a result, a plurality of (or even one) documents P on the document table 9 that are blocked by the stopper member 13 and are not allowed to enter the sheet feeding belt 11 are driven by the sheet feeding motor 61. It is pressed against the calling roller 10 and is sent to the separation unit D by the calling roller 10. In this case, the paper feeding belt 11 and the separation roller 12 are simultaneously driven by the paper feeding motor 61.
[0037]
The rotation state of the separation roller 12 is detected by the rotation detecting means 50 for a predetermined time until the document P enters the separation unit D from the document setting position, and this rotation state is detected by the comparator 65 in the pulse on the paper feed motor 61 side. Compared with signal. That is, the difference between the linear velocity of the separation roller 12 and the linear velocity of the paper feed belt 11 is detected from the pulse signals of the encoder 63 and the paper feed motor 61. At this time, if the separation roller 12 is rotating in the same direction as the paper feed belt 11 at a predetermined linear velocity or more (for example, 70% or more of the linear velocity of the paper feed belt 11), the CPU 60 causes the separation roller 12 to rotate. Is determined to be rotating normally, and the operation state of the paper feed motor 61 is maintained. Accordingly, the document P is fed to the separation unit D and conveyed one by one by the separation roller 12. When the separation roller 12 rotates in the same direction as the paper feed belt 11 at a predetermined linear velocity or less (for example, 70% or less of the linear velocity of the paper feed belt 11), the CPU 60 It is determined that the friction coefficient has decreased, and the cleaning or replacement of the paper feed unit (separation roller 12 or paper feed belt 11) is warned via the warning display device 67 while the operation state of the paper feed motor 61 is maintained. Further, when the separation roller 12 hardly rotates or reversely rotates in the same direction as the paper feed belt 11, the CPU 60 determines that a paper feed failure occurs due to a decrease in the friction coefficient of the separation roller 12, and the paper feed motor The driving of 61 is stopped, and a warning is given to the cleaning or replacement of the paper feed unit via the warning display device 67.
[0038]
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the warning display device 67 may perform only warning display based on the comparison data without the CPU 60 controlling the paper feed motor 61.
[0039]
As described above, the ADF 6 of the present embodiment can detect the rotational state of the separation roller 12 and determine the degree of decrease in the friction coefficient of the separation roller 12, that is, the separation roller 12 and the paper feed belt 11. Therefore, it is possible to prevent a document feed failure.
[0040]
【The invention's effect】
According to the first aspect of the present invention, the change of the friction coefficient between the separation roller and the rotating body can be detected by the detecting means, and the document feeding failure can be prevented.
[0041]
Furthermore, the change of the friction coefficient between the separation roller and the rotating body can be detected with high accuracy by the detecting means.
[0042]
According to the second aspect of the present invention, it is possible to prevent the conveyance failure of the original document by the control means.
[0043]
According to the third aspect of the present invention, it is possible to warn the operator of a paper feed abnormality, and it is possible to perform an appropriate process for preventing a conveyance failure.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an automatic document feeder according to an embodiment of the present invention.
FIG. 2 is a circuit diagram of a detection device for detecting a rotation state of a separation roller and determining a degree of decrease in a friction coefficient of the separation roller.
[Explanation of symbols]
6 ADF (Automatic Document Feeder)
11 Paper feed belt (rotating body)
12 Separation roller (separation roller)
50 Rotation detection means (detection means)
60 CPU (control means)
63 Encoder (detection means)
65 Comparator (detection means)
67 Warning display device (warning means)

Claims (3)

In an automatic document feeder that automatically separates set documents one by one and automatically conveys them to an image reading position, a rotating body that rotates in a paper feeding direction, a rotating body that presses against the rotating body, A separation roller that cooperates with the rotator to separate the sheets one by one, a detection unit that detects a rotation state of the separation roller, and a first pulse signal that measures the period of the first pulse signal according to the rotation state of the rotator A period measuring unit,
The detection means includes a second period measuring unit that measures a period of a second pulse signal according to a rotation state of the separation roller, a period measured by the first period measuring unit, and the second period. A comparator that compares the period measured by the measuring unit, and a time period from when the document is fed to the position between the separation roller and the rotating body, compared with the time period for comparison by the comparator. An automatic document feeder , wherein a difference between a linear velocity of the separation roller and a linear velocity of the rotating body is detected based on a result. Control means for controlling the document feeding operation based on the detection information from the detecting means, the control means, when the difference in linear velocity between the separation roller and the rotating body exceeds a set value, the document feeding operation The automatic document feeder according to claim 1 , wherein the automatic document feeder is stopped. Comprising a warning means for informing the abnormality of the feeding state, it exceeds the value linear velocity difference is set to the separation roller and the rotating body, according to claim 1, wherein the warning means is characterized by notifying the abnormality of the feeding state The automatic document feeder described in 1.

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