JP2007030993A - Automatic document feeder and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic document feeder (ADF) and an image forming device obtaining conveying roller driving strong in load variation by impact to a conveying roller drive system at driving of a separating means by adjusting strength of a conveying roller nipping pressure according to thickness of document paper to be passed. <P>SOLUTION: The automatic document feeder has a switch-back route 42 for separating a piled up bundle of documents by every one sheet, feeding it to an image reading position and reversing front and back of the document by switch-back conveying after the document is passed through a reading position; and a roller separating means 44 capable of releasing a nipping pressure of a pair of conveying rollers 37, 38 provided on the switch-back route 42. A fed current to a conveying roller drive source 51 is varied at driving of the roller separating means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an improvement of an image reading apparatus or an automatic document feeder (hereinafter referred to as ADF) mounted on an image forming apparatus, and more particularly to a sheet-through ADF that reads an image while conveying a document and an image forming apparatus including the sheet through ADF. It is.

Conventionally, it is known to use a switchback member that can contact and separate in a sheet-through ADF that reads an image while conveying a document (see, for example, Patent Documents 1 and 2).
In Patent Document 1, the distance at which the sheet feeding member (pickup roller) descends to the document bundle is made constant (short) by raising and lowering the placement table in accordance with the thickness of the document bundle on the placement table. Moreover, in patent document 2, in order to make the thickness of gluing uniform in gluing bookbinding, the gluing mounting base is made movable.
JP 2001-220026 JP JP 2002-254856 A

However, the prior arts of Patent Documents 1 and 2 both have a configuration in which the mounting table is moved in accordance with the thickness of the original bundle, and requires detection means for detecting a difference in thickness of one original. There is a demand for an apparatus that can change the document conveyance control for each sheet according to the thickness.
In view of the above, the object of the present invention is to adjust the strength of the conveyance roller nip pressure according to the thickness of the original paper to be passed, and to reduce the impact on the conveyance roller drive system when driving the separating means. An object of the present invention is to provide an ADF that obtains conveyance roller driving that is resistant to load fluctuations, and an image forming apparatus including the ADF.

In order to solve the above-described problem, the invention described in claim 1 separates the stacked original bundle one by one and feeds it to the image reading position, and the original is passed through the reading position by switchback conveyance. In an automatic document feeder having a switchback path for reversing the front and back of a document and a roller separation means capable of releasing the nip pressure of a pair of conveyance rollers provided in the switchback path, when the roller separation means is driven, to the conveyance roller drive source It features an automatic document feeder that changes the supply current.
According to a second aspect of the present invention, there is provided the automatic document feeder according to the first aspect, further comprising a control unit that uses a stepping motor as the conveyance roller driving source and switches the excitation method of the stepping motor to drive the roller separation unit. Features.
According to a third aspect of the present invention, there is provided control means capable of controlling a combination of switching of a supply current to the transport roller drive source and switching of an excitation method of the stepping motor according to the drive speed of the transport roller. The automatic document feeder according to claim 1 or 2 is characterized.
According to a fourth aspect of the present invention, there is provided an image forming apparatus equipped with the automatic document feeder according to any one of the first to third aspects.

  According to the present invention, by changing the current supplied to the conveyance roller drive motor when driving the roller separation means, it is possible to obtain conveyance roller drive that is resistant to load fluctuations due to impact on the conveyance roller drive system when driving the roller separation means. it can.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing a sheet-through type automatic document feeder according to the present invention. The basic configuration, operation, and action will be described according to the embodiment.
INDUSTRIAL APPLICABILITY The present invention is used in an apparatus that transports a document to be read to a fixed reading device unit and reads an image while transporting the document at a predetermined speed, and needs to transport two documents in different directions in document transportation. In some cases, the present invention relates to a sheet-through type automatic document feeder using a roller pair separating operation.
FIG. 2 is a schematic view showing a contact / separation operation mechanism of a paper discharge driven pressure roller controlled by a pressure motor of a driving source using stepping motor driving according to the present invention. FIG. 3 is a block diagram for explaining the control of the sheet-through type automatic document feeder according to the present invention.

In FIG. 1 and FIG. 3, the ADF is roughly composed of a document setting unit 1 for setting a document bundle 8 to be read, and a separation feeding unit 2 for separating and feeding documents one by one from the set document bundle 8. The registration unit 3 for temporarily abutting and aligning the fed document and for pulling out and transporting the aligned document, and turning the conveyed document so that the document surface faces the reading side (downward) A turn unit 4 for conveying, a reading conveying unit 5 for reading an image of a document from below a contact glass (reading glass) 30, a reverse switchback for reading the second surface and page alignment after reading both surfaces, or a document A reverse discharge unit 6 that discharges the document, a stack unit 7 that stacks and holds the originals after reading, drive units 48 to 52 that drive these conveyance operations, and a series of operations. It is divided into a controller portion 55.
The original bundle 8 to be read is set on the original setting table 9 with its leading end abutted against the position of the broken line of the original stopper 10, and the width direction of the original bundle 8 is set by side guides (not shown). Positioning is performed in the direction orthogonal to the transport direction.
In this state, the document set detection filler 12 is displaced from the broken line position to the solid line position, and as a result, the document set detection sensor 13 is released from light shielding. Then, a document set signal is transmitted to the main body control unit 54.
Further, a document length detection sensor 14 or 15 provided on the surface of the document setting table 9 (a reflective sensor or an actuator type sensor that can detect even one document is used) is a length in the document transport direction. However, the document width detection (width size) sensor 58 detects the width in the direction orthogonal to the conveyance direction and determines the outline of the document size (at least a sensor arrangement that can determine whether the document size is vertical or horizontal is necessary). ).
FIG. 4 is a flowchart for explaining the execution of the document feeding operation. FIG. 5 is a flowchart for explaining the execution of the document feeding operation following A in FIG. FIG. 6 is a flowchart for explaining the execution of the document feeding operation following B in FIG.

In FIG. 1, FIG. 3, FIG. 4 to FIG. 6, the processing operation of the document bundle 8 of the same size will be described first. A document feeding operation is executed by a document feeding signal (a signal input from an operation unit (not shown) and instructed from the main body control unit 54 to the controller unit 55 via the I / F unit 53).
It is determined whether or not the document is set (S1), and if it is a document set, the document stopper 10 is a CW (forward rotation, clockwise) drive of the driving device (calling motor) 48 (in the embodiment, a stepping motor). This can also be realized with a solenoid) (S2). It is determined whether or not the document stopper 10 is at the retracted position (S3).
Thereafter, the pickup roller 16 moves from the broken line position to the upper surface of the document indicated by the solid line position by the reverse drive of the driving device (calling motor) 48 (S4), and is pressed with a predetermined force. A home position sensor (HP sensor) 17 is a sensor for detecting the state of the pickup roller 16 and the document stopper 10.
Next, it is determined whether or not the pickup roller 16 is at the calling position (S5). If it is at the calling position, the calling motor 48 is stopped (S6). During the pressure contact operation of the pickup roller 16, when the number of documents is small, the drop height is large and the cushioning action of the document is small between the document setting table 9 and the pickup roller 16, so that the drop impact sound of the pickup roller 16 is generated. A bug that becomes larger occurs.
As a solution to this problem, a concave roller relief is formed at the contact point of the document setting table 9 with the pickup roller 16 so that the pickup roller 16 does not hit the document setting table 9 directly.
Thereafter, after a predetermined time, the drive source (paper feed motor) 49 for driving the separation feeding unit 2 and the registration unit 3 rotates in the CW (forward rotation) direction (S7), and the pickup roller 16 rotates in the clockwise direction. Then, the uppermost sheet of the sheet bundle 8 is fed in the direction of the separation feeding unit 2.
At this time, the paper feeding belt 18 is stretched around the belt pulleys 19 and 20 with a predetermined tension, and is pressed so as to be wound around a separation roller 21 provided in an opposing manner. The separation roller 21 is friction driven via a torque limiter (not shown) having a predetermined magnitude of torque.

When the separation roller 21 is directly engaged with the paper feeding belt 18 or is engaged through one original, the separation roller 21 is rotated counterclockwise as the paper feeding belt 18 rotates.
In the unlikely event that an original enters between the paper feed belt 18 and the separation roller 21 by two or more sheets, the accompanying force is set to be lower than the torque of the torque limiter, and the separation roller 21 is driven in the original driving direction. Rotate in the clockwise direction to push back the excess document, preventing double feed.
Further, the document separated into one sheet by the action of the paper feed belt 18 and the separation roller 21 is further fed by the paper feed belt 18, and the leading edge is detected by the abutting sensor 23 in the process of proceeding through the paper feed path 22. Then, it further hits the pull-out roller 24 that is stopped.
After that, a predetermined distance is fed from the detection of the abutting sensor 23, and as a result, the feed source 49 is rotated in the state where it is pressed against the pull-out roller 24 with a predetermined amount of warpage. The driving of the paper belt 18 is stopped.
The abutting amount is determined according to the document thickness information acquired so as to prevent damage to the leading edge of the document and noise during the abutting. The amount of the original that abuts against the pull-out roller 24 during the stop, which is performed for skew correction, is adjusted according to the original paper thickness. As a result, it is possible to prevent damage to the leading edge of the document at the time of butting.
It is determined whether or not the abutting sensor 23 is on (S8), and if it is on, the abutting amount count is started (S11). If it is not on, it is determined whether or not the jam detection time is over (S9), and if it is over, it is determined that the jam has not been reached (S10).

5, the calling motor 48 is rotated CCW (S12), it is determined whether the pickup roller 16 is at the retracted position (S13), and if it is at the retracted position, the calling motor 48 is stopped (S14). The document is fed by a predetermined amount from the detection of the abutting sensor 23, and it is determined whether the count value is equal to the predetermined pulse (S15).
As a result, the drive of the paper feed belt 18 is stopped by reversing the drive source (paper feed motor) 49 while being pressed against the pull-out roller 24 with a predetermined amount of bending (S16). Here, the drive source (reading motor) 50 is rotated forward.
Next, it is determined whether or not the width size sensor 58 is on (S17). If it is on, the document width information is transmitted (S18). It is determined whether or not the mixed loading mode is off (S19). Information is transmitted (S20).
At this time, by rotating the drive source (calling motor) 48 in the CCW direction, the pickup roller 16 is retracted from the upper surface of the original, and the original is fed only by the conveying force of the paper feeding belt 18, so that the front end of the original is pulled out by the pullout roller 24. The upper and lower roller pairs enter the nip, and the tips are aligned (skew correction).

Turning to FIG. 6, it is determined whether or not the nip-in sensor 27 is on (S21). If it is not on, it is determined whether or not the jam detection time is over (S22). .
If the nip-in sensor 27 is on, a correction count is started (S24), and it is determined whether the registration sensor 29 is on (S25). If not, it is determined whether the jam detection time is over (S26). The resist is not reached jam (S27).
If the registration sensor 29 is on, the registration stop pulse count is started (S28), and it is determined whether the count value is equal to the predetermined pulse (S29). If equal, the paper feed motor 49 and the reading motor 50 are stopped (S30), and a registration stop is transmitted (S31).
Thereafter, the pull-out roller 24 is driven by the reverse rotation of the drive source (paper feed motor) 49 to convey the document in the direction of the turn part 4. Here, when feeding the first sheet of the original bundle to the registration stop position, the conveyance speed of the pull-out roller 24 is set to be higher than the reading speed.
The reading conveyance roller 25 is also driven at the same speed by a driving source (reading motor) 50. In the case of the second and subsequent sheets, as will be described later, a form of first advance of the next original is taken.

FIG. 7 is a flowchart for explaining the next original advance operation. FIG. 8 is a flowchart for explaining the operation following F in FIG. FIG. 9 is a flowchart for explaining the operation following G in FIG.
Referring to FIG. 1, FIG. 3, FIG. 7 to FIG. 9, as shown in FIG. 7 to FIG. 9, it is determined whether or not the single-side mode is selected (S32). ). If it is not the single-sided mode, it is determined whether or not alternate conveyance is carried out (S34), and if double-sided originals are alternately conveyed, it is determined whether or not front side reading is being performed (S35). If it is not the alternate conveyance, it is determined whether or not the back side reading is completed (S36).
If the surface is being read in step S33, it is determined whether or not the butting sensor 23 is off (S37). The paper is fed so that the next original passes the first reading position after passing the second original reading position. In the case of single conveyance, paper feeding is started so that the next original passes through the first reading position after passing through the third reading position of the preceding original.
Since the reading conveyance roller 25 during reading of the document image is driven by the drive source (reading motor) 50 at a speed corresponding to the reading magnification instructed from the main body control unit 54, the conveyance speed of the next original is the speed of the reading conveyance roller 25. At the same speed, it must be fed into the nip between the reading conveyance roller 25 and the pressure roller 26.
Therefore, when the trailing edge of the document being read passes through the abutting sensor 23, pulse counting for controlling the gap between the sheets is started, and the advance feeding of the next document is started while monitoring the progress of the trailing edge of the document being read. (S38).
First, the drive source (calling motor) 48 is rotated forward. It is determined whether or not the pickup roller 16 is in the calling position (S39). If it is in the calling position, the calling motor 48 is stopped (S40).
The pickup roller 16 is brought into pressure contact with the upper surface of the next original, and then the drive source (paper feed motor) 49 is driven to rotate forward (S41) and is conveyed until it contacts the stopped pull-out roller 24.
It is determined whether or not the abutting sensor 23 is on (S42). If the abutting sensor 23 is on, the abutting amount counting is started (S43). If it is not ON, it is determined whether or not the jam detection time is over (S44), and if it is over the time, it is determined that a jam has not been reached (S45). The calling motor 48 is rotated CCW (S46).

Moving to FIG. 8, it is determined whether or not the pickup roller 16 is in the retracted position (S47). If it is in the retracted position, the calling motor 48 is stopped (S48). The original is fed a predetermined distance from the detection of the abutting sensor 23, and it is determined whether the count value is equal to the predetermined pulse (S49). If equal, the paper feed motor 49 is stopped (S50).
Next, it is determined whether the inter-paper pulse count is equal to a predetermined pulse (S51). If equal, the paper feed motor speed is set to the first-out speed (S52). CCW rotation (reverse rotation) of the paper feed motor 49 is started (S53).
Here, the position of the trailing edge of the document being read is calculated from the inter-paper pulse count value, and when a predetermined paper interval is advanced from the pull-out roller 24, the drive source (feed motor) 49 is driven in reverse, and the pull-out roller 24 It is driven at a high speed as in the first sheet. Here, it is determined whether or not the document width detection sensor 58 is on (53a). If it is on, the document width information is transmitted (53b). Then, it is determined whether or not the mixed mode is off (53c). Information is transmitted (53d).
It is fed to the nip-in sensor 27 at this speed, and it is determined whether or not the nip-in sensor 27 is on (S54). If it is not on, it is determined whether or not the jam detection time is over (S57). Judgment is made (S58).
If it is ON, it is decelerated to the reading speed (speed of the reading conveyance roller 25) by the detection of the leading end detection (nip-in) sensor 27 (S55). The correction counter is started when the leading edge detection (nip-in) sensor detects the leading edge of the document (S56).
A control pulse of the driving source (reading motor) 50 until the trailing edge of the document passes through the leading edge detection (nip-in) sensor portion (more specifically, when the driving source 50 is constituted by a stepping motor or a brushless motor) When the motor drive pulse or the drive source 50 is configured by a brush motor with an encoder, the encoder pulse) is counted. By performing this operation between successive original sheets, it is possible to recover the time stopped by the original abutting operation and maintain a predetermined original interval.

Turning to FIG. 9, as in FIG. 6, it is determined whether or not the registration sensor 29 is on (S59). If it is not on, it is determined whether or not the jam detection time is over (S60). (S61).
If the registration sensor 29 is on, the registration stop pulse count is started (S62), and it is determined whether the count value is equal to the predetermined pulse (S63). If the count value is equal, the paper feed motor 49 and the reading motor 50 are stopped. (S64), registration stop is transmitted (S65).
Further, when the pull-out roller 24 starts to be driven, a pulse count is started to detect the size in the conveyance direction, and the document length in the conveyance direction is calculated from the pulse count value when the trailing edge of the document passes the separation sensor 28.
The width of the leading end of the document that has passed the calculation result and the document width detection sensor (width size sensor) 58 is detected by the size detection sensor group in the direction orthogonal to the conveyance direction. An accurate document size is determined by a combination of the width signal and the length / width signal obtained by the document set detection filler 12 or the document length detection sensor 14.
This document size information is transmitted to the main body control unit 54 from the controller unit 55 via the I / F unit 53 (document length information transmission (S20 in FIG. 5), and the second and subsequent sheets are corrected counts in FIG. Start S56)).
Thereafter, the document is sent to the nip between the reading conveyance roller 25 and the pressure roller 26, and when the leading edge of the document is detected by the registration sensor 29, the registration counter is cleared.
The drive source (reading motor) 50 is stopped at a position where a predetermined pulse has been conveyed from there, and a registration stop signal is transmitted to the main body control unit 54, and a read start signal (synchronization with transfer paper or image memory) is sent from the main body control unit 54. (A signal transmitted at the time when preparation for storage in the storage is completed) is waited for (input of count value = predetermined pulse in FIG. 6 (S29)).

FIG. 10 is a flowchart for explaining an original reading operation by inputting a reading start signal. FIG. 11 is a flowchart for explaining the operation following C in FIG. FIG. 12 is a flowchart for explaining the operation following D in FIG.
Next, an original reading operation is executed by inputting a reading start signal. In FIGS. 1 to 3 and FIGS. 10 to 12, the reading motor speed is set from the reading magnification (S66). The forward rotation of the reading motor 50 is started and the tip count is started (S67).
The document whose registration is stopped is sent to the image reading unit 5 by the reading conveyance roller 25 and the pressure roller 26 which are rotated by the normal driving of the driving source (reading motor) 50.
The driving speed of the driving source (reading motor) 50 at this time is determined based on information transmitted from the main body control unit 54 to the controller unit 55 based on a reading magnification input from a main body operation unit (not shown).
In the reading conveyance unit 5, the document passes between the reading glass 30 and a white background plate 31 arranged on the upper surface thereof with a predetermined interval. During this time, an image is read by a reading system (not shown), is electrically converted via a CCD, and is stored in a memory device (not shown).
The reading / conveying unit 5 is provided with means for reducing the conveyance gap as much as possible and reducing the degree of freedom of the document as much as possible. As such a method, a method of projecting a flexible guide member (not shown) from the inner surface of the reading entrance guide 32 in the direction of the white background plate 31 and filling the gap is effective.
Further, the white background plate 31 is pressed on the reading glass 30 with a predetermined elasticity with a gap of about 0.5 mm ± 0.2 mm, and errors in the reading depth direction are also suppressed.
The surface of the reading glass 30 is treated with a surface active agent (silicon-based activator) so that ink or the like does not easily adhere or adhere to the surface. Further, the above-described flexible guide is extended to the vicinity of the reading point, and the document surface does not positively contact the reading glass 30 at the reading point position, and the leading edge of the document is wiped near the reading point of the reading glass 30 (the leading edge). The action of scraping off foreign matter on the glass surface) is adopted.

In FIG. 10, it is determined whether the count value is equal to the surface predetermined pulse (S68). If equal, it is determined whether the correction pulse is equal to the surface predetermined pulse (S69). If equal, the front DF gate on is transmitted (S70), and the front gate count is started (S71).
The timing at which the leading edge of the document reaches the reading conveyance unit 5 is controlled by a control pulse count of a driving source (reading motor) 50. It is determined whether the document nip-in sensor (nip-in sensor) 27 is off (S72). If it is off, a correction count is added to the document length data (S73).
Specifically, a comparison between a value obtained by converting a conveyance distance from the tip detection (nip-in) sensor 27 to the reading conveyance unit 5 into a motor control pulse and a correction counter value, and a conveyance distance from the registration sensor 29 to the reading conveyance unit 5 The value converted into a motor control pulse is compared with the count value of the registration counter.
It is checked whether or not the paper discharge sensor 39 is on (S74). If it is not on, it is determined whether or not the jam detection time is over (S75), and the paper discharge is not reached (S76).
If the paper discharge sensor 39 is on, the process moves to FIG. 11 to check whether the registration sensor 29 is off (S77). If it is not off, it is determined whether the jam detection time is over (S78). (S79).
If it is off, the trailing edge count is started (S80), and it is checked whether the count value is equal to the surface predetermined pulse (S81). If it is equal, the document length ≦ gate count value is checked (S82), and the gate count value is checked. Is equal to or larger than the document length, the front DF gate-off is transmitted (S83).
That is, if both comparison results are within a predetermined range, a surface DF gate signal indicating a surface image effective reading area in the sub-scanning direction is transmitted at that timing. Thereafter, the document advances while being read, and is fed to the reading exit roller 34 and the pressure roller 35 through the pickup guide 33.

Since the reading exit roller 34 and the pressure roller 35 are driven in common by the reading and conveying roller 25, the feeding speed and the drawing speed are the same, which has the effect of reducing the occurrence of a delivery shock.
The document sent out from the image reading / conveying unit 5 by the reading exit roller 34 is sent to the reverse paper discharge unit 6, and the branch claw 36 is lifted in the direction of the dotted line by using the tension of the document, and the paper discharge roller can be rotated forward and backward. 37 is conveyed to the nip of a discharge-driven driven pressure roller 38 configured to be able to contact and separate from 37.
Then, from the detection of the trailing edge of the document by the paper discharge sensor 39, the conveyance pulse count of the drive source (paper discharge motor) 51 decelerates the document when discharging and reverses it to the document stack unit 7. The drive source (paper discharge motor) 51 is stopped in a state where it is in the nip between the roller 37 and the paper discharge driven pressure roller 38, and the drive source (paper discharge motor) 51 is reversely rotated in the CCW direction (reverse switchback). ).
Then, the document is reversed upside down through the reversing path 40 and driving the pull-out roller 24. When reading the back side, the document reading operation is executed by inputting a reading start signal after stopping the registration like the front side.
In final reversal for page order alignment after double-sided reading, the pull-out roller 24, the reading roller 25, and the paper discharge roller 37 are controlled at the same speed without stopping registration, and high-speed conveyance is performed.

In FIG. 11, it is determined whether or not the duplex mode is selected (S84). If the duplex mode is selected, it is determined whether or not the reverse switchback is completed (S85). If completed, it is checked whether the count value is equal to the predetermined pulse on the back side (S86). .
If they are equal, it is checked whether or not the correction pulse is equal to the predetermined back side pulse (S87), and if equal, the back side DF gate on is transmitted (S88), the back side gate count is started, and the correction count is stopped (S89).
Turning to FIG. 12, it is checked whether the count value is equal to the predetermined pulse on the back side (S90). If it is equal, the document length ≦ gate count value is checked (S91), and the gate count value is equal to or equal to the document length. If larger, the back side DF gate off is transmitted (S92).
Next, it is determined whether or not the reverse switchback is completed (S93), and if it is completed, it is checked whether or not the paper discharge sensor is off (S94). If it is not off, it is determined whether or not the jam detection time is over (S95), and the paper discharge stay jam is determined (S96).
Further, due to the separation operation of the paper discharge driven pressure roller 38 by the pressure motor 52 of the driving source, in the case of alternate conveyance, the original P1 (not shown) after reading the back side and the next original P2 (not shown) at the time of reading the front side. However, in the case of single conveyance, control is performed so that the leading edge and the trailing edge of the original at the time of reversal are conveyed in opposite directions while partially overlapping in the switchback path 40 (see FIG. 2).
Further, the discharge stacker 41 is configured to be high on the downstream side, which contributes to prevention of jumping out of the discharged document and improvement of stacking document alignment accuracy. Further, the document setting table 9 is configured so as to be able to retreat upward with the rotation fulcrum 47 as the center, thereby improving the stack document extraction performance.

Returning to FIG. 2, this figure shows a contact / separation operation mechanism of the paper discharge driven pressure roller 38 controlled by a pressure motor 52 (see FIG. 3) as a driving source. The contact / separation operation mechanism of the paper discharge driven pressure roller 38 will be described with reference to FIG. First, the pressure motor 52 controls the rotational movement of the cam 44.
By this rotational movement, the connecting member 57 of the cam 44 and the paper discharge driven roller 38 reciprocates in the vertical direction, and the paper discharge driven roller 38 can be contacted and separated through the fulcrum of the connecting member 57. A separation claw 36 is provided to guide the document from the switchback path 42 to the reversal path 40. The cam 44 side of the connecting member 57 is pressed by elastic means 32 such as a spring.
The stop timing of the pressure motor 52 is controlled based on the detection of the pressure release sensor 46. The pressure release sensor 46 is arranged so that the contact / separation state of the paper discharge driven pressure roller 38 can be recognized by a predetermined pulse drive of the pressure motor 52. In particular, when pressure is applied to the paper discharge roller 37, pressure is applied while the pressure motor 52 is controlled to decelerate so as to suppress load fluctuation as much as possible.

FIG. 13 is a flowchart of the separation operation of the paper discharge driven pressure roller controlled by the pressure motor and the reverse switchback operation controlled by the paper discharge motor in the alternate conveyance according to the present invention. FIG. 14 is a flowchart for explaining control following G in FIG.
When the discharge motor driven pressure roller 38 is changed from the separated state to the contact (pressurization) state, the pressure motor 52 is controlled after the pressure release sensor 46 is detected. Deceleration control is started so that the pressurization motor 52 stops at a position where it contacts with a predetermined pressure.
If there is a document being conveyed on the sheet discharge roller 37 at the time of pressurization, a pressure operation is performed while controlling the sheet discharge motor of the drive source 51 to be equal to the conveyance direction and conveyance speed of the document being conveyed.
On the other hand, the separation operation of the paper discharge driven pressure roller 38 sets the driving speed of the pressure motor 52 faster than the pressure operation. In the present embodiment, the contact / separation operation of the paper discharge driven pressure roller 38 is performed by motor driving, but may be driven by a solenoid.
Further, the drive source (paper discharge motor) 51 of the paper discharge roller 37 improves the torque output of the drive motor by switching the drive current setting at the timing when the pressure release sensor 46 contacts the paper discharge driven pressure roller 38. In addition, by switching the excitation method to microstep drive, the step angle is reduced in a pseudo manner, and the drive of the discharge roller 37 is stabilized.

Referring to FIGS. 1 to 3, 13, and 14, in the case of alternate conveyance, the next original P <b> 2 (not shown) when the first original P <b> 1 (not shown) passes the second reading position. Starts feeding at the timing of passing the first reading position. It is determined whether the reading of the front side of the original document has been completed (S97). If it has been completed, it is determined whether the paper discharge sensor 39 is off (S100).
If it is off, the paper discharge motor 51 is stopped after a predetermined pulse, and high-speed CW rotation (switchback) is performed (S101). That is, when the front document P1 has already completed double-sided scanning and is in reverse switchback for page order alignment, the next document P2 is reading the front side.
At this time, the paper discharge roller 37 is CCW-rotated (reversely rotated) for reversing the original document P1 with respect to the conveyance direction of the next original P2. Therefore, in order to prevent the next original P2 from buckling, it is determined whether or not the butting sensor 23 is on (S102). If it is not ON, it is determined whether or not the jam detection time is over (S103), and if the time is over, the abutting unachieved jam is determined (S104).
If it is ON, after a predetermined pulse, the pressure motor 52 is rotated (separated) at high speed by CW (forward rotation) (S105). That is, when the leading edge of the leading document P1 is driven to drive the pull-out roller 24 by pulse count from the leading edge detection of the leading document P1 of the abutting sensor 23 (the trailing edge until now becomes the leading edge after reverse switchback). In addition, the pressure motor (stepping motor) 52 as a driving source is driven at a high speed to vertically move the paper discharge driven pressure roller 38 toward the dotted line portion, thereby separating the nip portion from the paper discharge roller 37.

Next, it is determined whether the pressure release sensor 46 is on (S106). If it is on, the pressure motor 52 stops after a predetermined pulse from the detection of the pressure release sensor 46 (S107). This separation operation enables the originals P1 and P2 to be conveyed in opposite directions while partially overlapping in the switchback path.
Next, it is determined whether or not the next original surface reading is completed (S108). If completed, the pressure motor 52 is operated at a low speed in a state where the paper discharge motor 51 is controlled in CCW rotation (current setting value: H, excitation switching: μ step). Rotate (CCW rotation control) (S109).
Next, it is determined whether or not the pressure release sensor 46 is off (S110). If it is off, the pressure motor 52 is decelerated after a predetermined pulse and then stopped (S111). That is, the pressure motor 52 is controlled so that the discharge driven pressure roller 38 is re-pressurized (solid line) after the reading of the next original surface is completed.
In the repressurization, since the next original P2 is on the paper discharge roller 37, the discharge motor 51 of the driving source is controlled to be equal to the conveyance direction and the conveyance speed of the next original P2, and the discharge due to load fluctuation at the time of pressurization In order to prevent out-of-step and noise of the paper motor 51 and the pressure motor 52, the pressure motor 52 is decelerated from the detection of the pressure release sensor so as to reduce the load fluctuation.
Specifically, based on the detection of the pressure release sensor 46, the discharge motor driven pressure roller 38 is brought into contact with the discharge roller 37 at a predetermined pressure, and the pressure motor 52 is decelerated so that the pressure motor 52 stops at the same time. Determine the start timing.
At this time, by switching the supply current to the drive source 51 of the paper discharge roller 37 in a stepwise manner according to the document reading speed, a motor torque that can withstand load fluctuations due to an impact at the time of contact with the paper discharge driven pressure roller 38 is obtained. To be obtained.
Further, by switching the phase excitation method of the drive source 51 to microstep drive, the displacement angle per step is reduced, and control is performed to suppress the influence on the rotational speed as much as possible even if load fluctuation occurs.

Turning to FIG. 14, it is determined whether or not the paper discharge sensor 39 is off (S114). If it is off, the paper discharge motor 51 is stopped after a predetermined pulse, and high-speed CW rotation (switchback) is performed (S115). That is, when the front document P1 has already completed double-sided scanning and is in reverse switchback for page order alignment, the next document P2 is reading the front side.
It is determined whether or not the butting sensor 23 is on (S116). If it is not ON, it is determined whether or not the jam detection time is over (S117), and if the time is over, the abutting unachieved jam is determined (S118).
If it is ON, after a predetermined pulse, the pressure motor 52 is rotated at high speed by CW (forward rotation) (S119). That is, the drive motor pressure motor (stepping motor) 52 is driven at a high speed, and the paper discharge driven pressure roller 38 is moved vertically toward the dotted line portion to separate the nip from the paper discharge roller 37.
Next, it is determined whether the pressure release sensor 46 is on (S120). If it is on, the pressure motor 52 stops after a predetermined pulse from the detection of the pressure release sensor 46 (S121). This separation operation enables the originals P1 and P2 to be conveyed in opposite directions while partially overlapping in the switchback path.
Next, the pressurization motor 52 is rotated at a low speed in a state where the paper discharge motor 51 is CCW-rotated (current setting value: H, excitation switching: μ step) (S122). Subsequently, it is determined whether or not the pressure release sensor 46 is off (S123). If it is off, the pressure motor 52 is decelerated and stopped (repressurized) after a predetermined pulse (S124).
That is, after the next document P2 is switched back, the pressure motor (stepping motor) 52 is controlled (pressure release sensor detection) by the pulse count after the abutting sensor 23 detects the leading edge of the next document P2 similarly to the previous document P1. And then the paper discharge driven pressure roller 38 is separated.
Control is performed so that the first original P1 that has been reversed for page ordering and the next original P2 that is being reversed for back side reading are conveyed in opposite directions while partially overlapping in the switchback path 42.
At the timing when the trailing edge of the next original P2 passes through the nip of the paper discharge roller 37, the paper discharge vertical pressure roller 38 is re-pressurized while the paper discharge motor 51 is controlled to be equal to the conveyance direction and the conveyance speed of the first original P1. .
Since the next original P2 is on the paper discharge roller 37, the pressurization is performed by controlling the paper discharge motor 51, which is a driving source, to be equal to the conveyance direction and the conveyance speed of the next original P2, and by a load variation at the time of pressurization. In order to prevent step-out and noise of the paper discharge motor 51 and the pressure motor 52, the pressure motor 52 is controlled while being decelerated so as to reduce the load fluctuation.

Next, it is determined whether or not the paper discharge sensor 51 is off (S125). If it is not off, it is determined whether or not the jam detection time is over (S126). If the time is over, it is determined that the paper discharge stays jam (S127).
If it is off, the paper discharge motor 51 is decelerated and controlled by the pulse count from the trailing edge detection of the paper discharge sensor 39 (S128), and the original document P1 is discharged so that the original does not jump out of the stack section 7. Then, the paper discharge completion is transmitted (S129).
The front document P1 is controlled so as to decelerate the discharge motor 51 based on the pulse count from the detection of the trailing edge of the discharge sensor 39, and is discharged from the stack unit 7 so that the document does not jump out. In the final reversal for page alignment, high-speed conveyance control is performed in consideration of productivity while maintaining a gap between the next original and the paper.
In these pressurization controls, the deceleration start timing is determined by adjusting the feed amount (pulse count) based on the detection of the pressure release sensor 46. By adjusting the applied pressure, slip of the transport roller (paper discharge roller 37) can be reduced, and productivity can be maintained as much as possible.

FIG. 15 is a flowchart of the contact / separation operation of the paper discharge driven pressure roller controlled by the pressure motor in the single conveyance and the reverse switchback operation controlled by the paper discharge motor. FIG. 16 is a flowchart for explaining the control following H in FIG.
Next, the case of single conveyance will be described. In the case of single conveyance, especially when the original length in the conveyance direction is reversed after switchback, and the length where the leading and trailing edges of the original overlap on the paper discharge roller 37 in the switchback path, the discharge follow-up is performed in the same manner as alternate conveyance. The control includes the separation operation of the pressure roller 38.
In the single conveyance, when the first original P1 passes through the third reading position (reversed for page ordering), the feeding starts so that the next original P2 passes through the first reading position. During reading, there is always one document in the path.
In FIG. 15, it is determined whether or not surface reading is completed (S130). It is determined whether or not the paper discharge sensor 39 is off (S131). If it is off, the paper discharge motor 51 is stopped after a predetermined pulse, and high-speed CW rotation (switchback) is performed (S132). Next, the resist is stopped (S133), and reading of the back surface is started (S134).
At the start of reading the back side, the trailing edge of the document is placed on the nip of the paper discharge roller 37, so the paper discharge motor 51 rotates CCW (reverse). At this time, in the case of single conveyance, the leading end of the document that has been read is caught in the nip of the paper discharge roller 37 before the rear end of the document passes through the nip of the paper discharge roller 37. To do.
It is determined whether the paper discharge sensor 39 is on (S135). If it is not ON, it is determined whether or not the jam detection time is over (S136). If the time is over, the paper discharge sensor 39 is not reached (S137). If it is ON, high-speed CW rotation (separation) of the pressure motor 52 is performed after a predetermined pulse (S138).

Next, it is determined whether the pressure release sensor 46 is on (S139), and the pressurization motor 52 is stopped after a predetermined pulse (S140). The separation timing is performed before starting the image reading in order to suppress the load fluctuation as much as possible because the image may be affected during the image reading.
Then, it is determined whether or not the back side scanning is completed (S141). After the back side scanning is completed, the rotation direction and the rotation speed of the paper discharge motor 37 at the timing when the rear end of the document passes through the nip of the paper discharge roller 37 based on the document size information. Is controlled at the same speed as the document transport conditions (current setting value: H, excitation switching: μ step), the pressure motor 52 is rotated at a low speed (CCW rotation) so as to re-press the discharge driven pressure roller 38. Control is performed (S142).
At this time, similarly to the alternate conveyance, the supply current to the drive source of the paper discharge roller 51 is switched stepwise in accordance with the document reading speed, thereby tolerating the load fluctuation due to the impact at the time of contact with the paper discharge driven pressure roller 38. The motor torque to be obtained can be obtained.
Further, by switching the phase excitation method of the drive source 51 to microstep drive, the displacement angle per step is reduced, and control is performed to suppress the influence on the rotational speed as much as possible even if load fluctuation occurs.
By switching the excitation method of the drive source (stepping motor) 51 of the roller separation means, it is possible to obtain a stable conveyance roller drive against load fluctuation due to an impact on the conveyance roller drive system when the separation means is driven.
In addition, since it has control means that can be controlled by combining supply current switching to the transport roller drive motor and stepping motor excitation method switching according to the transport roller drive speed, motor drive control suitable for the roller drive speed is possible It becomes.
Next, it is determined whether the pressure release sensor 46 is off (S143). In order to prevent out-of-step between the discharge motor 51 and the pressurization motor 52 due to load fluctuations at the time of re-pressurization, and the pressure release sensor 46, the discharge motor 46 is activated while the deceleration control is started from the detection of the pressure release sensor 46. The pressure roller 38 is re-pressurized (S144).

Turning to FIG. 16, it is determined whether or not the paper discharge sensor 39 is off (S145). If it is not off, it is determined whether or not the jam detection time is over (S146). If the time is over, it is determined that the paper discharge stays jam (S147). If it is off, if it is off, the paper discharge motor 51 is stopped after a predetermined pulse, and high-speed CW rotation (switchback) is performed (S148).
That is, in order to withstand the impact during pressurization as described above, and in the reverse switchback operation after completion of reading of the front surface or back surface, the document is driven after the trailing edge of the document has passed the reading exit roller 34 as in the case of alternate conveyance. The source 51 is controlled at high speed.
Next, it is determined whether or not the paper discharge sensor 39 is on (S149). If it is not ON, it is determined whether or not the jam detection time is over (S150). If the time is over, the abutting unachieved jam is determined (S151).
After the final reversal for page order alignment, the paper discharge sensor 39 is on, and the separation operation is performed when the paper discharge sensor 39 detects the leading edge of the document in the same way as when reading the back side. That is, the high-speed CW rotation (separation) of the pressure motor 52 is performed after a predetermined pulse (S152).
Next, it is determined whether the pressure release sensor 46 is on (S153), and the pressurization motor 52 is stopped after a predetermined pulse (S154). Based on the document size information, the rotation direction and rotation speed of the discharge motor 37 are controlled to be equivalent to the document transport conditions at the timing when the trailing edge of the document passes the nip of the discharge roller 37 (current setting value: H, The excitation motor 52 is controlled to rotate at low speed (CCW rotation) so as to re-pressurize the discharge-driven driven pressure roller 38 at excitation switching (μ step) (S155).
Next, it is determined whether the pressure release sensor 46 is off (S156), and after a predetermined pulse, the pressure motor 52 is decelerated and stopped (S157). That is, the pressure motor 52 is controlled so as to re-pressurize at the timing when the trailing edge of the document passes through the nip of the paper discharge roller based on the document length information.
As described above, the re-pressurization is performed while the discharge motor 51 is set to be equivalent to the document transport condition and the pressurization motor 52 is controlled to be decelerated. Then, it is determined whether or not the paper discharge sensor 39 is off (S158). If it is not off, it is determined whether or not the jam detection time is over (S159). If the time is over, a paper discharge stay jam is detected (S160).
If it is off, the discharge motor 51 is decelerated and stopped by the pulse count from the detection of the trailing edge of the discharge sensor 39 (S161), and the document is discharged from the stack unit 7 so as not to jump out. Then, the paper discharge completion is transmitted (S162).

1 is a cross-sectional view illustrating a sheet-through type automatic document feeder according to the present invention. It is the schematic which shows the contact-separation operation mechanism of the discharge driven pressure roller controlled by the pressure motor of the drive source using the stepping motor drive by this invention. FIG. 3 is a block diagram illustrating control of a sheet-through type automatic document feeder according to the present invention. 6 is a flowchart illustrating execution of a document feeding operation. 5 is a flowchart illustrating execution of a document feeding operation following A in FIG. 4. 6 is a flowchart illustrating execution of a document feeding operation following B in FIG. 5. 6 is a flowchart illustrating a next original advance operation. It is a flowchart explaining the operation | movement following F of FIG. It is a flowchart explaining the operation | movement following G of FIG. 6 is a flowchart illustrating an original reading operation by inputting a reading start signal. It is a flowchart explaining the operation | movement following C of FIG. It is a flowchart explaining the operation | movement following D of FIG. 6 is a flowchart of a separation operation of a paper discharge driven pressure roller controlled by a pressure motor and a reverse switchback operation controlled by a paper discharge motor in alternate conveyance according to the present invention. It is a flowchart explaining the control following G of FIG. 6 is a flowchart of a contact / separation operation of a paper discharge driven pressure roller controlled by a pressure motor and a reverse switchback operation controlled by a paper discharge motor in single conveyance. It is a flowchart explaining the operation | movement following H of FIG.

Explanation of symbols

ADF automatic document feeder 37 Conveying roller pair (discharge roller)
38 Conveying roller pair (discharged driven roller)
42 Switchback path 44 Roller separation means (cam)
51 Drive source (stepping motor, paper discharge motor)
52 Drive source (stepping motor, pressure motor)
55 Control means (controller part)

Claims (4)

  A switchback path that feeds the originals separated from the original bundle one by one to the image reading position, and reverses the front and back of the original by switchback conveyance after the original passes the reading position, and the switchback path. In the automatic document feeder having a roller separation unit capable of releasing the nip pressure of the pair of conveyance rollers and a control unit, the control unit changes a supply current to the conveyance roller driving source when the roller separation unit is driven. An automatic document feeder characterized by causing   2. The automatic document feeder according to claim 1, wherein a stepping motor is used as the conveyance roller drive source, and the control unit switches the excitation method of the stepping motor to drive the roller separation means.   3. The control unit according to claim 1, wherein the control unit controls the supply current switching to the transport roller driving source and the excitation method switching of the stepping motor in combination according to the driving speed of the transport roller. Automatic document feeder.   An image forming apparatus comprising the automatic document feeder according to any one of claims 1 to 3.

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