JPH10167494A - Sheet material carrying device and image reading device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the detection accuracy of the position of a carried sheet manuscript and speed up a processing by detecting the passage of the rear end of the carried sheet manuscript at the more upperstream side of the carrying direction than a separation part and grasping the time until the rear end of the sheet manuscript passes the separation part accurately. SOLUTION: A rear end passage detection sensor 60 provided in the more upperstream than the separation part 7 detects the passage of the rear end of the previous sheet manuscript S. After a constant time, the pickup roller 6 is lowered toward a paper feed position by CPU control and landed onto the next sheet manuscrip S. Further, after a constant time, the pick up roller 6 is rotated and the next sheet manuscript S is carried and when its tip reaches a paper detection sensor staying in the downstream of the separation part 7, the pick up roller is risen toward a stand by position. Thereby, the processing speed can be improved by grasping the time until the passage of the separation part 7 from the passage of the rear end passage detection sensor 60 of the rear end of the sheet manuscript S accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus such as a scanner, an image forming apparatus such as a laser beam printer, an image reading apparatus such as a copying machine or a facsimile, and an apparatus provided with the image forming apparatus. The present invention relates to a sheet conveying device applied to an automatic document conveying device and the like provided in the apparatus.

[0002]

2. Description of the Related Art Conventionally, as a separating / conveying means provided in a sheet conveying apparatus of this kind, a comb-tooth separating system in which a feeding roller and a separating belt are arranged in a comb-like manner, which has a high double feed prevention effect, is used. It is common.

[0003] As a drive control structure of the separation / conveyance means in the sheet material conveyance apparatus according to the prior art, a sheet leading end detection sensor is provided further downstream of a pair of pull-out rollers provided downstream of the separation / conveyance means in the conveyance direction. Then, when the leading end of the sheet material reaches a predetermined position, the driving of the separation / conveying means is stopped after a predetermined time from the detection time.

The driving of the separating / conveying means is stopped in order to keep the distance between the sheet materials (the distance between the previously conveyed sheet material and the next conveyed sheet material) at a predetermined value. In order to prevent double feeding of the sheet material (if the operation of the separating and conveying means is continued even after the rear end of the previously conveyed sheet material has passed through the separating and conveying means, the next conveyed sheet material is separated. It is necessary to prevent this since the sheet is conveyed without moving the sheet). Control is performed so that the driving is stopped before the trailing end of the sheet material passes through the separating and conveying means, and thereafter, the downstream of the separating and conveying means. By the pulling roller pair on the side,
The sheet material is pulled out and transported to the downstream side.

[0005]

However, in the case of the prior art described above, a sheet leading end detecting sensor provided further downstream of a pair of pull-out rollers provided downstream of the separating and conveying means in the conveying direction. In the above, the leading edge of the sheet material is detected, and the time required for the sheet material to pass through the separating / conveying means is calculated therefrom, and the drive stop timing of the separating / conveying means is determined. The error was large.

[0006] Therefore, taking into account temporal variations and the like,
The drive was stopped early with considerable time, and the drawing roller was used to pull out a long distance.

While the sheet material is being pulled out, the feed roller rotates, but the rotation of the separation belt is stopped. Therefore, the sheet material and the pull-out roller are separated by the sliding resistance between the sheet material and the separation belt. In some cases, a slip may occur, and the actual conveyance speed may decrease, and the sheet material may not reach the reading position at a regular time.

[0008] In particular, when a sheet material having different lengths in the conveying direction is conveyed in a mode of conveying a series of operations,
Since the drive stop timing of the separation / conveying means is determined in accordance with the shortest sheet material that can be conveyed, in the case of a long-sized sheet material, the distance to be pulled out by the pulling-out roller becomes longer, and the error due to slip increases. There was something.

Further, in a recent digital image forming apparatus which combines digital reading and memory storage, the speed of image reading is required to be increased with the speed of printing. Without increasing speed,
In order to improve the processing speed of the actual sheet material, the position where the sheet material is being conveyed is accurately grasped and the interval between the sheet materials (between the sheets) is shortened, so that it can be shortened in a short time. There is a technical need to process many sheet materials.

[0010] However, in the above-mentioned configuration of the prior art, it is difficult to meet such technical requirements due to a large error due to slip or the like.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to improve the accuracy of detecting the position of a conveyed sheet material and to increase the processing speed. An object of the present invention is to provide a sheet conveying apparatus, an image reading apparatus, and an image forming apparatus having excellent reliability.

[0012]

In order to achieve the above object, according to the present invention, there is provided a sheet feeding means for feeding a sheet material stacked on a sheet material stacking section, and a sheet fed by the sheet feeding means. Separating and conveying means for separating and conveying the sheet materials one by one, conveying means for conveying the sheet material separated and conveyed by the separating and conveying means, and conveying means provided upstream of the separation and conveying means in the conveying direction. Detecting means for detecting the passage of the trailing end of the sheet material to be carried out, and control means for controlling the drive stop timing of the separation / conveying means based on the detection signal of the detecting means.

The separating / conveying means includes a forward rotating member which rotates in a forward direction for feeding the sheet material fed by the paper feeding means in a conveying direction, and a sheet material fed while overlapping the sheet material in the original direction. A reverse rotation member that rotates in a direction to return to the normal rotation member, and a driving unit that drives the forward rotation member and the reverse rotation member. The control unit controls the sheet to be fed in the conveyance direction based on a detection signal of the detection unit. The rotation of the forward rotation member and the reverse rotation member is stopped before the rear end of the material passes through the holding portion between the forward rotation member and the reverse rotation member, and after receiving the transfer force from the transfer means. The driving means may be controlled as described above.

In the case where the sheet material is continuously conveyed, the control means controls the next sheet by the sheet supply means after a predetermined time when the detection means detects the passage of the rear end of the previous sheet material. A sheet feeding operation may be performed, and after it is confirmed that the sheet material has been separated and conveyed by the separation and conveyance unit, the sheet feeding operation by the sheet feeding unit may be stopped.

It is preferable that a rotational driving force is transmitted to the forward rotation member and the reverse rotation member by a stepping motor.

It is preferable that the detection means is provided so as to be able to contact the sheet material conveyed by the sheet material stacked on the sheet material stacking section.

The detecting means includes a light-transmitting portion which rotates by frictional force received from a conveyed sheet material and transmits light emitted in a direction parallel to the rotation axis, and a light-shielding portion which blocks the light. And a light receiving unit for receiving the transmitted light, and detecting passage of the rear end of the conveyed sheet material from a light receiving cycle of receiving light by the light receiving unit.

The detecting means may be provided substantially at the center in the width direction of the sheet orthogonal to the sheet conveying direction.

The image reading apparatus may include reading means for reading a document image of a document sheet conveyed by the sheet material conveying apparatus.

The image forming apparatus may be provided with an image forming means for forming an image of image information sent from the outside on the sheet conveyed by the sheet conveying apparatus.

[0021]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, shape, relative arrangement, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

(First Embodiment) FIGS. 1 to 10 show a sheet conveying apparatus and an image reading apparatus to which the sheet conveying apparatus according to a first embodiment of the present invention is applied. I have.

FIG. 1 is a schematic sectional view of an image reading apparatus according to the first embodiment.

Reference numeral 1 denotes an image reading device; 2, a document reading unit for reading a sheet document S, which is a running sheet material, by a flow reading method; 3, a sheet conveying device for feeding the sheet document S to the document reading unit 2; It is an automatic document feeder.

The automatic document feeder 3 includes a stacking tray 5, which is a sheet material stacking section capable of stacking a plurality of sheet documents S,
Pickup roller 6 as a paper feeding means for taking out sheet documents one by one, separating unit 7 as a separating / conveying means for separating and feeding multi-fed sheet documents S one by one, and separating unit 7
A pair of pull-out rollers 8 as conveying means for pulling out the sheet document S separated and conveyed by the above, a pair of conveying rollers 9, 10 and 11 for conveying the sheet document S pulled out by the pair of pull-out rollers 8 to the document reading section 2, and reading is completed. And a pair of conveying rollers 13, 14, and 15 for conveying the sheet document S to the discharge tray 12.

Here, the automatic document feeder 3 includes a lower limit sensor 31 for detecting the standby position of the stacking tray 5 and a sheet height sensor for keeping the height of the uppermost sheet of the sheet original at the time of paper feeding constantly. 32 are provided.

Further, on the stacking tray 5, the sheet original S is located upstream of the pickup roller 6 in the sheet original transport direction.
A rear end passage detection sensor 60 is provided as a detecting means for detecting that the rear end has passed.

The image reading apparatus 1 comprises a first mirror base 16 as a scanning optical unit as reading means, a second and third mirror base 17, a lens 18, and a CCD sensor 19 as a reading element. The first mirror table 16 is provided with an exposure lamp 20 for irradiating the sheet document surface, a reflection shade 21, and a first mirror 22 for changing the direction of reflected light of the illuminated sheet document. The second and third mirror bases 17 further include a second mirror 23 and a third mirror 24 that further change the angle of the reflected light whose angle has been changed by the first mirror 22 and guide the reflected light to the CCD sensor 19 through the lens 18. Provided. The first mirror base 16 has a contact glass 26
, And constitutes the document reading unit 2.

Next, the operation of the image reading apparatus 1 according to the present embodiment will be described.

When the user of the image reading apparatus stacks the sheet originals S on the stacking tray 5 and instructs the start of image reading by an operation unit (not shown), first, the exposure lamp 20 is turned on, and then the sheet feeding is performed. The operation starts. The stacking tray 5 starts to rise from the standby position, and continues to rise until the uppermost sheet of the stacked sheet documents S is detected by the sheet height sensor 32.

Then, the pickup roller 6 drops from the standby position onto the uppermost sheet of the sheet document S and rotates to send out the sheet document S, and the separation unit 7 separates the unnecessary sheet document S, and picks up the sheet document S. The roller 6 moves up to the standby position again.

Then, the separated sheet document S is conveyed to the image reading section 2 by the pull-out roller 8 and the conveying rollers 9, 10, and 11. Then, the sheet document S is illuminated by the exposure lamp 20 while being conveyed. The reflected light is guided to the lens 18 by the mirrors 22, 23, and 24, and forms an image on the CCD sensor 19. Thereafter, the sheet document S is transported further downstream by the transport rollers 13, 14 and 15, and is discharged to the discharge tray 12. This series of operations is repeated until all of the sheet documents S are exhausted from the stacking tray 5, and when all the sheets are exhausted, the stacking tray 5 is lowered to the standby position, and the exposure lamp 20 is turned off.

Next, the horizontal raising and lowering operation of the loading tray 5 will be described in detail with reference to FIGS.

FIG. 2 is a schematic structural view showing the operation of lifting and lowering the stacking tray 5, and is a side view as viewed from the direction of the separation unit 7. FIG. 3 is a bottom view of the loading tray 5. FIG. 4 is a conceptual diagram of the operation of the paper height sensor 32.

FIG. 2A shows a state where the stacking tray 5 is waiting at the standby position. The user of the image reading apparatus 1 stacks the sheet documents S on the stacking tray 5 and moves the pair of left and right side guides 33 in a direction perpendicular to the sheet document S transport direction in order to prevent skew when the sheet document S is transported. To the width of

When a copy start is instructed by an operation unit (not shown), the start signal is transmitted to the control means C
A control signal is input to the PU 50, and a control signal is input from the CPU 50 to the drive motor 34, which is a drive unit, and the drive motor 34 rotates the drive gear 35 counterclockwise. Then, the sector gear 36 and the arm 38 integrally attached to the sector gear 36 are driven by the drive gear 35 around the shaft 36a.
And the idler gear 37 rotates in the direction of the arrow. Thereby, the loading tray 5 is raised via the support rollers 39 rotatably attached to the arm 38. Here, reference numeral 31 denotes a lower limit sensor for detecting the standby position of the loading tray 5, which is fixedly supported by the frame 40. In addition, although the description has been made using the configuration in which the transmission is performed by the driving force gear from the driving motor 34, the same applies to the case where the transmission is performed by the belt.

Next, stop control of the ascent operation will be described.

FIG. 4A shows the state of the sheet height sensor 32 when the stacking tray 5 is waiting at the standby position, and FIG.
Indicates a state when the sheet document S is at the sheet feeding position. 32a is a light transmission type photo sensor, 32b is a flag for turning on / off the photo sensor 32a,
The photo sensor 32a is supported so as to be able to move up and down.

When the stacking tray 5 is waiting at the standby position, the flag 32b is lowered as shown in FIG. 7A, and the photo sensor 32a transmits light and recognizes the off state. When the stacking tray 5 rises, the flag 32b is pushed up by the top sheet of the sheet document S, and when the sheet document S reaches the sheet feeding position, the flag 32b enters between the photo sensors 32a as shown in FIG. By turning off the light, the state is turned on, and the rotation of the drive motor 34 is stopped by a control circuit (not shown).
State.

When the sheet document S is sequentially fed from the uppermost sheet, the height of the uppermost sheet gradually decreases, and accordingly, the flag 32b also decreases. Then, since the photo sensor 32a transmits light and enters the Off state, a series of operations in which the drive motor 34 is driven again until the photo sensor 32a enters the On state is repeated until the sheet document S is exhausted.

Next, stop control of the descending operation will be described. The lower limit sensor 31 includes a main body 31a, an arm 31
b, the switch section 31c, and when the stacking tray 5 is in the sheet feeding state, as shown in FIG.
Is separated from the main body 31a and the switch 31c,
It is in the f state. Then, as shown in FIG. 2A, when the drive motor 34 rotates in the reverse direction, the stacking tray 5 descends, and the stacking tray 5 pushes the arm 31b and the switch 31c is pushed, the state changes to the On state. Then, the rotation of the drive motor 34 stops.

Further, a guide configuration at the time of raising and lowering operation of the loading tray 5 will be described with reference to FIG.

The loading tray 5 has four abutting rollers 41 rotatably supported by the loading tray 5, two of which are pressed against the frame 40 by a compression spring 42 while being pressed against the frame 40. Have been. Therefore, the stacking tray 5 is positioned between the frames 40 without play in the direction perpendicular to the sheet document conveyance direction (the direction of the arrow). On the other hand, the frame 40 has a guide portion 40a provided in the vertical direction of the stacking tray 5 by the operating range length,
Since the abutting rollers 41 are guided by the guide portion 40a without play, the position of the stacking tray 5 in the transport direction of the sheet document S (the direction of the arrow in the drawing) is determined. Thus, the stacking tray 5 can move up and down with respect to the frame 40 in the horizontal direction with respect to the sheet document stacking surface without play.

Next, referring to FIG. 5, FIG. 6, and FIG. 7, the structure of the pickup roller 6 as the paper feeding means, the operation at the time of paper feeding, and the trailing end detection sensor which is a feature of the present embodiment will be described. The configuration of the pickup 60 and the operation control of the pickup roller 6 based on the detection signal of the rear end passage detection sensor 60 will be described in detail.

First, FIG. 5 shows a rear end passage detecting sensor 60.
In the figure, reference numeral 61 denotes a rotating roller as a rotating member, a core 61a, a roller 61b made of a rubber material, and a disk 61.
The disk 61c is provided with holes 61d as light-transmitting portions at equal intervals and at equal angles. A rotation shaft 62 rotatably supports the rotation roller 61 and is fixedly supported by a holder 63. Numeral 64 denotes a light transmission type photo sensor having a light receiving portion, which is fixed to the holder 63,
1c is detected. The rear end passage detection sensor 60 is rotatably supported by a not-shown apparatus main body through a hole 63a of the holder, and has its own weight according to the height of the uppermost sheet of the sheet document S. I'm riding.

When the roller 61 is rotated by the frictional force received from the sheet original S in response to the operation of transporting the sheet original S, the disk 61c is similarly rotated, and accordingly, the sensor 64 is moved to the hole 61d. And a light-shielding portion formed by a portion having no hole alternately outputs Hi / Low signals in accordance with a light receiving cycle in which the light receiving portion receives light.
Send to PU50.

FIG. 6 is an upper perspective view showing a driving structure of the pickup roller 6 in the vertical movement. The pickup roller 6 is rotatably mounted on an arm 72, and the arm 72 is rotatable about a shaft 73. Installed. Further, the pickup roller 6 is rotatable by a driving force of a driving motor 76 via driving belts 74 and 75. Further, the rotation of the arm 72 is controlled by the rotation support lever 77.
Is rotatable about a shaft 78, and the rotation support lever 77 is rotated, and is rotated by pushing up the E portion. The rotation support lever 77 is rotatable by a stepping motor 80 via a drive belt 79.

With the above configuration, the pickup roller 6
The rotation of the stepping motor 80 causes the rotation support lever 77 to push up the arm 72 upward, the standby position away from the sheet document S, the rotation support lever 77 to move down, and the pickup roller 6 to move the pickup roller 6 over the sheet document S. Can be switched to the paper feed position that is in contact with. In addition, by driving the drive motor 76 at the sheet feeding position of the pickup roller 6, the pickup roller 6 rotates,
The sheet original S is sent out from the uppermost sheet. Here, as described above, the trailing edge passage detection sensor 60 is located upstream of the pickup roller 6 in the transport direction of the sheet document S and substantially at the center in the width direction of the sheet document S orthogonal to the transport direction. Is provided.

When the trailing edge detection sensor 60 is
In the apparatus that conveys the sheet document S on the basis of the center when the sheet roller is disposed substantially at the center in the width direction of the sheet document, the rotating roller 6 is always positioned at the center of the sheet document S in the width direction regardless of the size of the sheet document S.
1 contacts. Therefore, even if a load is applied to the sheet document S from the rotating roller 61, the sheet document S does not skew.

FIG. 7 is a graph showing the control of the vertical movement of the pickup roller 6. The upper part shows the Hi / Low of the output signal of the rear end passage detection sensor 60, and the lower part shows the position of the pickup roller 6. ing.

First, when the preceding sheet document S is being conveyed under the conveyance force of the separation unit 7 or the pull-out roller 8, the output signal of the rear end passage detection sensor 60 becomes F (time) in the figure. Hi / Low are repeated at regular intervals until the end. When the rear end of the preceding sheet document S passes at F (time), the signal output becomes constant,
At F (time), it can be detected that the rear end of the previous sheet document S has passed the rear end passage detection sensor 60.

Then, based on the detection, at step G (time) after a predetermined time, the CPU 50 sends the signal to the stepping motor 80.
, The pickup roller 6 at the standby position starts descending toward the sheet feeding position by the rotation of the motor 80, and lands on the next sheet document S at H (time). Here, the rear end is the rear end passage detection sensor unit 6.
The sheet document S that has passed through 0 has passed through the pickup roller 6 by H (time), and the pickup roller 6 does not come into contact with the previous sheet document S being conveyed.

Further, at I (time) after a predetermined time, a rotation command is issued from the CPU 50 to the drive motor 76, the pickup roller 6 rotates, the next sheet S is conveyed, and the output signal of the sensor is Again, Hi / Low is repeated at equal intervals. Then, when the leading edge of the next sheet document S reaches the paper detection sensor (not shown) downstream of the separation unit 7, the CPU 50 sends the stepping motor 80.
, A rotation command is issued, and the pickup roller 6 at the sheet feeding position starts rising toward the standby position by the rotation of the motor 80, returns to the standby position at K (time), and prepares for the next sheet feeding operation. Here, the rotation of the drive motor 76 is stopped at K (time) when the pickup roller 6 returns to the standby position.

Next, referring to FIGS. 8, 9 and 10, the structure of the separation unit 7 and the like as separation / conveyance means, the operation during separation / conveyance, and the rear end passage detection sensor which is a feature of this embodiment. The operation control of the separation unit 7 based on the 60 detection signals will be described in detail.

First, the configuration of the separation unit 7 will be described.
The front side plate 121, the rear side plate 122, and the lower paper guide 128 are fixed by screws, respectively, and constitute a frame of the separation unit 7. Feeding roller 117 as forward rotation member
Is that the feed roller shaft 117a has the front plate 121 and the rear plate 12
2 is rotatably supported via a bearing (not shown).

Also, a separation belt 11 as a reverse rotation member
One end of 8 is hung on a belt driving roller 118b integrally attached to the belt driving shaft 118a, and the other end is hung on a belt driven roller 118c rotatably held on a belt driven shaft 118d. Here, the belt driven shaft 118d is fixed to the belt side plate 126 with screws, and the belt side plate 126 is rotatably supported on the belt drive shaft 118a via a bearing (not shown). In addition, the separation belt 118 collides with an abutting portion (not shown),
It is arranged so as to penetrate the feeding roller 117 by a predetermined penetration amount F.

On the other hand, a roller gear 123 and a belt gear 125 are integrally attached to one end of the feed roller shaft 117a and the belt drive shaft 118a on the front plate 121 side, respectively, and an idler gear 124 is rotatable on the front plate 121 therebetween. Supported.

Then, the driving force from the automatic document feeder 3 is input to the belt gear 125 and the idler gear 124
Is transmitted to the roller gear 123 via the As a result, when the separation belt 118 is rotationally driven in the direction of arrow A (the reverse rotation direction for returning the sheet document S), the feeding roller 117 is rotated.
Are driven to rotate in the forward rotation direction in which the sheet document S is transported in the transport direction. Therefore, the sheet document S to be conveyed on the feed roller 117 side is fed and conveyed by the feed roller 117 in the direction of arrow B in the figure, and the other sheet documents S are returned by the separation belt 118 so that one sheet Are transported separately.

Next, the structure for fixing and supporting the separating section 7 will be described. The front plate 121 and the rear plate 122 respectively have
Circular holes 121a, 122a and a circular long hole (front side plate 121)
The side 121b is provided, and the rear plate 122 side is not shown). Reference numerals 131 and 132 denote frames of the main body of the automatic document feeder 3, and a fixed shaft 133 is fixed to one of the frames 132 by caulking. The fixed support unit 130 is screwed and fixed to the other frame 131.

Here, the support unit 130 will be described in more detail. 134 is a case of the support unit 130, 135 is a lid, and is fixed by screws.
Reference numeral 6 denotes a slide fixed support shaft slidably supported by the case 134 and the lid 135, and a handle 137 is fixed to the slide fixed support shaft 136 by caulking. A pressing spring 138 is inserted between the cover 135 and the handle 137 to press the fixed support shaft 136 in the direction of the separating portion 7. Due to these, the separation unit 7 is provided with the round holes 121a,
122a and the round holes 121b, 122b (the front side plate 1).
The fixed shaft 133 and the slide fixed support shaft 136 are respectively provided on the 21 side 121b and the rear plate 122 side not shown).
Is inserted, and is supported in a state of being pressed toward the fixed shaft 133 by the slide fixed support shaft 136 pressed in the direction of arrow E by the pressing spring 138.

Further, the rotation drive section 140 of the separation section 7 will be described. As shown in FIG. 10, reference numeral 141 denotes a drive motor, which uses a stepping motor having almost no time lag in terms of electric control.
2 are integrally mounted, and the gear holder 144 is rotatably mounted via a bearing (not shown). The gear holder 144 includes an oscillating gear 143 rotatably mounted on an oscillating gear shaft 145 so as to mesh with the driving gear 142. Further, one end of a tension spring 146 is hooked on the gear holder 144, and the other end is hooked on the frame 131. As a result, the swing gear 143 is pressed upward around the drive motor shaft 141a and meshes with the belt gear 125. Here, when the butting portion 125b of the belt gear 125 and the butting portion 143b of the swing gear 143 abut, the gear portions 125a and 143a can engage with each other while maintaining a regular inter-axis distance, and accurately transmit the driving force. I do.

Here, the drive control of the separation unit 7 will be described. In order to open a predetermined sheet interval between sheet documents, a separation pair (feed roller 1) in which the rear end of the sheet document is still a holding portion.
17 and the separation belt 118), the driving is stopped, and thereafter, the sheet document S is transported by the pulling roller pair 9 and the conveying roller pairs 9, 10, and 11 on the downstream side.
Need to be transported.

In the case where two or more sheet documents S are conveyed to the separation unit 7 by the pickup roller 6 while driving is continued, the first sheet document S is
This is because if the sheet is removed, the second sheet document S is also conveyed without opening the sheet interval.

For this reason, the passage of the trailing edge of the sheet document S is detected by the trailing edge detection sensor 60 as described above, and the CPU 50 calculates the time required for the trailing edge of the sheet document S to pass through the separation unit 7 to calculate the sheet document S. Immediately before the rear end of S passes through the separation unit 7, a predetermined distance (for example, about 10 mm) is
Drive motor 14 so that it stops when it is
1 is controlled to stop.

The roller gear 123 has a one-way clutch so that even if the sheet original S is pulled out and conveyed by only the pulling-out roller pair 9, the feeding roller 117 can be rotated in the direction of arrow D. Has become.

By performing the above-described configuration and operation control, the separation section is moved after the rear end of the sheet material passes through the rear end passage detection sensor 60 regardless of the length of the conveyed sheet document S in the conveyance direction. 7, it is possible to accurately grasp the time required to pass through the sheet document 7, so that it is possible to minimize the distance for pulling out the sheet document in any length of the sheet document. Slip can also be reduced, and high productivity sheet conveyance becomes possible.

Further, by using a stepping motor for the drive motor 141 of the separation unit 7, there is no electrical time lag when the drive is stopped, and the drive is applied until just before the trailing edge of the sheet document passes through the separation unit 7. And the slip can be further reduced.

(Second Embodiment) In the first embodiment, the case where the sheet conveying device is applied to feed the sheet original of the image reading apparatus has been described. It is also possible to apply a sheet material (recording paper or the like) on which an image is formed by the image reading device to a conveyance device for feeding the image material to the image forming unit at the same timing.

Hereinafter, a case where the present invention is applied to a printer will be described with reference to FIG. FIG. 11 is a schematic configuration diagram of a printer 150 as an image forming apparatus. In addition,
In the first embodiment, the sheet conveying device is applied to the image reading apparatus. However, in the present embodiment, a case where the sheet conveying device is applied to the recording sheet conveying unit of the image forming apparatus will be described. Since other configurations and operations are the same as those of the first embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted.

However, in the present embodiment, the recording paper S as the sheet material on the stacking tray 5 which is the sheet material stacking section is separated and conveyed by the direct separation section 7, so that it is the same as in the first embodiment. The separating unit 7 has a function of a suitable sheet feeding means.

As shown in the figure, based on image information sent from the outside, a laser beam having image information is
The light is emitted from 51 to the image forming means 152.

Further, the recording paper S on the stacking tray 5 is separated and conveyed from the separation unit 7 to the image forming means 152 via a pair of pull-out rollers 8 as conveying means in accordance with the image forming timing. Transport.

In this embodiment, similarly to the first embodiment, the fact that the trailing end of the recording paper S has passed over the stacking tray 5 located on the upstream side of the separation unit 7 will be described. A rear end passage detection sensor 60 is provided as a detection unit for detecting. Then, when the trailing edge of the recording paper S is detected,
By controlling the drive stop of the separation unit based on this detection,
The same effect as in the first embodiment can be obtained.

(Third Embodiment) FIG. 12 shows a third embodiment of the present invention. In the first embodiment, the separating portion 7 of the automatic document feeder, which is a sheet material transporting device, has a configuration using a comb-teeth separation method in which a feeding roller and a separation belt are arranged in a comb shape. But,
In the present embodiment, the configuration adopts a so-called retard system. Other configurations and operations are the same as those of the first embodiment, so that the same components are denoted by the same reference numerals and description thereof will be omitted.

FIG. 12 is a schematic structural view of the vicinity of the separating section 7. As shown in the drawing, the separation unit 7 separates and conveys by a retard method. Since the separation and conveyance by the retard method is publicly known, details thereof are omitted, but the sheet material S is separated and conveyed one by one by a feed roller 181 and a retard roller 182.

In this embodiment, as in the first embodiment, the fact that the trailing end of the recording paper S has passed over the stacking tray 5 located upstream of the separation unit 7 is considered. Rear end passage detection sensor 60 as detection means for detecting
Is provided. By detecting the passage of the trailing edge of the recording sheet S and controlling the drive stop of the separation unit based on the detection, the same effect as in the first embodiment can be obtained.

(Fourth Embodiment) FIG. 13 shows a fourth embodiment of the present invention. In the first embodiment, the separating portion 7 of the automatic document feeder, which is a sheet material transporting device, has a configuration using a comb-teeth separation method in which a feeding roller and a separation belt are arranged in a comb shape. But,
In the present embodiment, the configuration adopts a so-called separation pad system. Other configurations and operations are the same as those of the first embodiment, so that the same components are denoted by the same reference numerals and description thereof will be omitted.

FIG. 13 is a schematic structural view of the vicinity of the separating section 7. As shown in the drawing, the separation section 7 separates and conveys the sheet by a separation pad. Since the separation and conveyance by the separation pad method is publicly known, the details thereof are omitted, but the sheet material S is transported one by one by the conveyance roller 191 and the separation pad 192.
Are transported separately.

In this embodiment, similarly to the first embodiment, the fact that the trailing end of the recording paper S has passed over the stacking tray 5 located on the upstream side of the separation unit 7 is considered. Rear end passage detection sensor 60 as detection means for detecting
Is provided. By detecting the passage of the trailing edge of the recording sheet S and controlling the drive stop of the separation unit based on the detection, the same effect as in the first embodiment can be obtained.

[0080]

According to the sheet conveying apparatus of the present invention, the detecting means for detecting the passage of the rear end of the conveyed sheet material is provided upstream of the separating and conveying means in the conveying direction. Regardless of the length of the sheet in the conveyance direction, the time from when the trailing edge of the sheet passes through the detection means to when it passes through the separation and conveyance means can be accurately grasped, and the position of the sheet being conveyed can be determined. The detection accuracy is improved, and the drive stop timing of the separation / conveyance means is controlled based on the detection signal, so that the processing speed can be increased.

On the basis of the detection signal of the detecting means, before the rear end of the sheet material fed in the conveying direction passes through the holding portion between the forward rotating member and the reverse rotating member constituting the separating and conveying means, and If the control means controls the rotation of the forward rotation member and the reverse rotation member to be stopped after receiving the conveyance force from the conveyance means, the conveyance can be performed while maintaining a predetermined distance between the sheet materials.

When the sheet material is continuously conveyed,
A predetermined time after the detection means detects the passage of the rear end of the previous sheet material, the feeding operation of the next sheet material by the sheet feeding means is performed, and it is determined that the sheet material is separated and conveyed by the separation conveyance means. If the sheet feeding operation by the sheet feeding means is stopped after the confirmation, each sheet material can be fed at regular intervals.

If the forward rotation member and the reverse rotation member transmit the rotational driving force by the stepping motor, the rotational drive having excellent control characteristics can be transmitted.

If the detecting means is provided so as to be able to contact the sheet material to be conveyed, the sheet material stacked on the sheet material stacking section,
The passage of the rear end of the conveyed sheet material can be detected by the sheet material stacking unit.

The detecting means includes a light-transmitting portion that rotates by frictional force received from the conveyed sheet material and transmits light emitted in a direction parallel to the rotation axis, and a light-shielding portion that blocks the light. By providing a light receiving unit that receives the transmitted light, the rotation of the rotating member stops and the light receiving cycle changes when the conveyed sheet material passes. It is possible to detect that the rear end has passed.

If the detecting means is provided at substantially the center in the width direction of the sheet orthogonal to the sheet conveying direction, skewing of the sheet document can be prevented.

As described above, it is possible to apply a highly reliable sheet material conveying device capable of increasing the processing speed to an image reading apparatus having a reading unit or an image forming apparatus having an image forming unit. it can.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an image reading apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram illustrating an operation of lifting and lowering a stacking tray provided in the image reading apparatus according to the first embodiment of the present invention.

FIG. 3 is a top view of the loading tray of FIG. 2;

FIG. 4 is a conceptual diagram of a paper surface height sensor placed on a stacking tray of FIG. 2;

FIG. 5 is a schematic configuration diagram of a rear end passage detection sensor provided in the image reading device according to the first embodiment of the present invention.

FIG. 6 is an upper perspective view showing a driving configuration of a vertical movement of a pickup roller provided in the image reading apparatus according to the first embodiment of the present invention.

FIG. 7 is a conceptual graph showing an output signal of a rear end passage detection sensor and a position of a pickup roller.

FIG. 8 is a lower perspective view of a separation unit provided in the image reading apparatus according to the first embodiment of the present invention.

FIG. 9 is a cross-sectional view showing a support state of the separation unit in FIG. 8;

FIG. 10 is an upper perspective view of a driving unit that drives a separation unit provided in the image reading apparatus according to the first embodiment of the present invention.

FIG. 11 is a schematic configuration diagram of an image forming apparatus according to a second embodiment of the present invention.

FIG. 12 is a schematic configuration diagram of a main part of a sheet material conveying device according to a third embodiment of the present invention.

FIG. 13 is a schematic configuration diagram of a main part of a sheet material conveying device according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image reading device 2 Document reading part 3 Automatic document feeder 5 Stacking tray 6 Pickup roller 7 Separation part 8 Pull-out roller pair 50 CPU 60 Rear end passage detection sensor 61 Rotation roller 61c Disk 61d hole 62 Rotation axis 64 Light transmission type photo sensor 117 feed roller 118 separation belt 141 drive motor (stepping motor) 150 printer 151 laser light source 152 image forming means 181 feed roller 182 retard roller 191 transport roller 192 separation pad

Claims (9)

[Claims] A sheet feeding means for feeding the sheet material stacked on the sheet material stacking section; a separating and conveying means for separating and conveying the sheet materials fed by the sheet feeding means one by one; Conveying means for conveying the sheet material separated and conveyed by the separating and conveying means, detecting means provided upstream of the separation and conveying means in the conveying direction, and detecting passage of a rear end of the conveyed sheet material; Control means for controlling a drive stop timing of the separation / conveyance means based on a detection signal of the means. 2. The method according to claim 1, wherein the separating / conveying means includes a forward rotating member rotating in a forward direction for feeding the sheet material fed by the paper feeding means in a conveying direction, and a sheet material fed while overlapping the sheet material. A reverse rotation member that rotates in the direction to return to the direction of, and a driving unit that drives the forward rotation member and the reverse rotation member, the control unit, based on a detection signal of the detection unit,
The forward rotation member and the reverse rotation before the rear end of the sheet material fed in the transportation direction passes through the holding portion between the forward rotation member and the reverse rotation member, and after receiving the transportation force from the transportation means. The sheet conveying apparatus according to claim 1, wherein the driving unit is controlled so as to stop the rotation of the member. 3. When the sheet material is continuously conveyed, the control means controls the next sheet feeding means by a predetermined time after the detection means detects the passage of the rear end of the previous sheet material. The sheet feeding operation of the sheet material is stopped after confirming that the sheet material has been separated and conveyed by the separation / conveying means. The sheet material conveying device according to item 1. 4. The sheet conveying apparatus according to claim 2, wherein a rotational driving force is transmitted to the forward rotation member and the reverse rotation member by a stepping motor. 5. The apparatus according to claim 1, wherein said detecting means is provided so as to be able to abut on a sheet material conveyed by the sheet material stacked on said sheet material stacking section. The sheet material conveying device according to any one of the above. 6. A light-transmitting portion which rotates by frictional force received from a conveyed sheet material and transmits light emitted in a direction parallel to a rotation axis, and intercepts the light. A light-receiving part for receiving the transmitted light; and detecting passage of a rear end of the sheet material conveyed from a light-receiving cycle of receiving light by the light-receiving part. The sheet material conveying device according to claim 5, wherein 7. A sheet conveying apparatus according to claim 1, wherein said detecting means is provided substantially at the center of a sheet width direction orthogonal to the sheet conveying direction. 8. An image reading apparatus, comprising: reading means for reading a document image of a document sheet conveyed by the sheet material conveying apparatus according to any one of claims 1 to 7. 9. An image forming apparatus comprising an image forming means for forming an image on a sheet conveyed by the sheet conveying apparatus according to claim 1. Description: