JP3397606B2 - Sheet material transport device, image reading device, and image forming device - Google Patents

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 apparatus including an image reading apparatus and an image forming apparatus such as a copying machine and a facsimile, and these apparatuses. The present invention relates to a sheet material conveying device applied to an automatic document conveying device or the like provided in the.

[0002]

2. Description of the Related Art Conventionally, as a separating / conveying means provided in this kind of sheet material conveying device, a comb-teeth separating system in which a feeding roller and a separating belt are arranged in a comb-teeth shape having a high effect of preventing double feeding is used. Is common.

As a drive control configuration of the separating / conveying means in the sheet material conveying device according to the prior art, a sheet front end detection sensor is provided further downstream of the pair of pulling rollers provided in the conveying direction downstream of the separating / conveying means. The detection of the leading edge of the sheet material reaching a predetermined position, and the driving of the separating and 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 sheet material conveyed first and the sheet material conveyed next) as predetermined. , To prevent double feeding of sheet materials (if the operation of the separating and conveying means continues even after the trailing edge of the previously conveyed sheet material has passed through the separating and conveying means, the sheet material to be conveyed next has a gap. This is because it is conveyed without doing so, and it is necessary to prevent this.) The drive is controlled so that it stops before the trailing edge of the sheet material passes through the separating / conveying means, and then the downstream side of the separating / conveying means. By the pulling roller pair on the side,
The sheet material is pulled out and conveyed downstream.

[0005]

However, in the case of the prior art as described above, the sheet leading edge detection sensor provided further downstream of the pair of pulling rollers provided downstream of the separating and conveying means in the conveying direction. Detects the leading edge of the sheet material and calculates the time for the sheet material to pass through the separating / conveying means, and determines the drive stop timing of the separating / conveying means. The error was large.

Therefore, in consideration of time variations and the like,
The drive was stopped early with a lot of time, and I was pulling out a long distance with the pull-out roller.

While the sheet material is being pulled out, the feeding roller is rotated, but the rotation of the separation belt is stopped, so that the sheet material and the extraction roller are separated by the sliding resistance of the sheet material and the separation belt. The slip may occur and the actual transport speed may become slow, and the sheet material may not be able to reach the reading position at the regular time.

In particular, when the sheet materials having different lengths in the conveying direction are conveyed in a mode of conveying in a series of operations,
Since the drive stop timing of the separating / conveying means is determined according to the shortest sheet material that can be conveyed, in the case of a long size sheet material, the distance to be pulled out by the pulling roller becomes longer and the error due to slippage is large. There was a chance

Further, in recent digital image forming apparatuses that combine digital reading, memory storage, etc., there is a demand for high-speed image reading along with high-speed printing. Without increasing the speed
In order to substantially improve the processing speed of the sheet material, it is necessary to accurately grasp the position where the sheet material is being conveyed and reduce the interval (sheet interval) between the sheet materials in a short time. There is a technical need to process many sheet materials.

However, it is difficult to meet such a technical requirement with the above-mentioned configuration of the prior art because the error due to the slip or the like is large.

The present invention has been made to solve the above-mentioned problems of the prior art. The object of the present invention is to improve the detection accuracy of the position of the conveyed sheet material and to increase the processing speed. Another object of the present invention is to provide a sheet material conveying device, an image reading device, and an image forming device which are excellent in reliability.

[0012]

In order to achieve the above object, according to the present invention, a sheet feeding means for feeding a sheet material stacked in a sheet material stacking portion, and a sheet feeding means for feeding the sheet material. Separating and conveying means for separating and conveying the sheet materials one by one, conveying means for conveying the sheet materials separated and conveyed by the separating and conveying means, and conveying means provided upstream of the separating and conveying means in the conveying direction. And a control means for controlling the drive stop timing of the separating / conveying means based on a detection signal of the detecting means.

The separating and conveying means feeds the sheet material fed by the sheet feeding means in the conveying direction and rotates the forward rotating member in the forward direction, and the sheet material fed while overlapping the sheet material in the original direction. A reverse rotation member that rotates in the direction of returning the sheet, and a drive unit that drives the forward rotation member and the reverse rotation member, and the control unit sends the sheet in the conveyance direction based on the 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 sandwiching portion between the forward rotation member and the reverse rotation member and after receiving the carrying force from the carrying means. The drive means may be controlled as described above.

When the sheet material is continuously conveyed, the control means, after a predetermined time after the detection means detects that the trailing edge of the previous sheet material has passed, the next sheet by the paper feeding means. The sheet feeding operation may be stopped after the sheet feeding operation is performed and it is confirmed that the sheet material has been separated and conveyed by the separating and conveying means.

Rotational driving force may be 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 in the sheet material stacking section.

The detecting means is rotated by a frictional force received from the conveyed sheet material and transmits a light emitted in a direction parallel to the rotation axis, and a light shielding portion which blocks the light. It is preferable that a light receiving unit that receives the transmitted light be provided, and that the passage of the rear end of the sheet material conveyed from the light receiving cycle in which the light receiving unit receives the light is included.

It is preferable that the detecting means is provided substantially at the center in the width direction of the sheet orthogonal to the sheet conveying direction.

The image reading device may be provided with a reading unit for reading the original image of the original sheet conveyed by the sheet material conveying device.

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 material conveyed by the sheet material conveying apparatus.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions of the components described in this embodiment,
Unless otherwise specified, the material, shape, relative arrangement, etc., are not intended to limit the scope of the present invention thereto.

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

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

Reference numeral 1 is an image reading device, 2 is a document reading unit for reading a sheet document S, which is a running sheet material, by a flow reading method, and 3 is a sheet material 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 unit capable of stacking a plurality of sheet documents S,
A pickup roller 6 as a sheet feeding unit that takes out the sheet originals one by one, a separating unit 7 as a separating and conveying unit that separates and conveys the multi-fed sheet originals S one by one, and a separating unit 7.
A pair of pulling rollers 8 serving as a conveying unit that pulls out the sheet document S that has been separated and conveyed by the pair of conveying rollers 9, 10 and 11 that conveys the sheet document S pulled out by the pair of pulling rollers 8 to the document reading unit 2 and finishes reading. It is composed of a pair of transport rollers 13, 14, 15 for transporting the sheet original S to the discharge tray 12.

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

Further, on the stacking tray 5, the sheet document S is provided on the upstream side of the pickup roller 6 in the sheet document conveying direction.
A trailing edge passage detection sensor 60 is provided as a detecting means for detecting that the trailing edge has passed.

The image reading apparatus 1 is composed of a first mirror stand 16 as a scanning optical unit which is a reading means, a second and third mirror stand 17, a lens 18, and a CCD sensor 19 as a reading element. The first mirror stand 16 is provided with an exposure lamp 20 for irradiating the surface of the sheet original, a reflection shade 21, and a first mirror 22 for changing the direction of the reflected light of the irradiated sheet original. The second and third mirror bases 17 are provided with a second mirror 23 and a third mirror 24 which further change the angle of the reflected light whose angle is changed by the first mirror 22 and guide the reflected light to the CCD sensor 19 through the lens 18. It is equipped. The first mirror stand 16 has a contact glass 26.
It is fixed substantially below and constitutes the document reading unit 2.

Next, the operation of the image reading apparatus 1 of this 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 is fed. The operation is started. The stacking tray 5 starts rising from the standby position and continues rising 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 is rotated to send out the sheet document S, and the separating section 7 separates the unnecessary sheet document S and picks it up. The roller 6 moves up to the standby position again.

Then, the separated sheet original S is conveyed to the image reading section 2 by the pull-out roller 8 and the conveying rollers 9, 10, 11. Then, the sheet original 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, 24 and forms an image on the CCD sensor 19. After that, the sheet document S is transported further downstream by the transport rollers 13, 14, 15 and discharged onto the discharge tray 12. This series of operations is repeated until all the sheet originals S are removed from the stacking tray 5, and when all the sheet originals S are exhausted, the stacking tray 5 is lowered to the standby position to finish, and the exposure lamp 20 is turned off.

Next, the horizontal lifting operation of the stacking tray 5 will be described in detail with reference to FIGS.

FIG. 2 is a schematic view showing the lifting operation of the stacking tray 5, which is a side view seen from the direction of the separating section 7. FIG. 3 is a bottom view of the stacking tray 5. FIG. 4 is a conceptual diagram of the operation of the paper height sensor 32.

FIG. 2A shows a state in which the stacking tray 5 is waiting at the waiting position. The user of the image reading apparatus 1 stacks the sheet originals S on the stacking tray 5, and in order to prevent the skew of the sheet originals S during conveyance, a pair of left and right side guides 33 is provided in a direction perpendicular to the conveying direction of the sheet originals S. To the width of.

When a copy start is instructed by an operation unit (not shown), the start signal is C which is the control means.
The signal is input to the PU 50, and a control signal is input from the CPU 50 to the drive motor 34 that is the drive means, and the drive motor 34 rotates the drive gear 35 in the counterclockwise direction. Then, the fan-shaped gear 36 and the arm 38 integrally attached to the fan-shaped gear 36 are attached to the drive gear 35 about the shaft 36a.
And the idler gear 37 rotates in the direction of the arrow. As a result, the stacking tray 5 is raised via the support roller 39 rotatably attached to the arm 38. Here, 31 is a lower limit sensor that detects the standby position of the stacking tray 5, and is fixedly supported by the frame 40. In addition, here, although the description has been given by using the configuration in which the driving force from the driving motor 34 is used for transmission, the same applies to the case where transmission is performed by a belt.

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

FIG. 4A shows the state of the paper surface height sensor 32 when the stacking tray 5 stands by at the standby position, and FIG.
Shows the state when the sheet document S is at the sheet feeding position. Reference numeral 32a is a light-transmitting photosensor, and 32b is a flag for turning on / off the photosensor 32a.
The photo sensor 32a is supported so as to be vertically movable.

When the stacking tray 5 is on standby at the standby position, the flag 32b is lowered as shown in (a), and the photosensor 32a transmits light and recognizes it as an OFF state. Then, when the stack tray 5 rises, the flag 32b is pushed up by the uppermost sheet of the sheet document S, and when the sheet document S reaches the sheet feeding position, the flag 32b enters between the photosensors 32a as shown in (b). By turning off the light, the state becomes ON, and the rotation of the drive motor 34 is stopped by a control circuit (not shown).
It becomes the state of.

When the sheet document S is sequentially fed from the uppermost sheet, the height of the uppermost sheet is gradually lowered, and the flag 32b is also lowered accordingly. 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, the stop control of the descending operation will be described. The lower limit sensor 31 includes a main body 31a and an arm 31.
2b and a switch section 31c, when the stacking tray 5 is in a sheet feeding state, as shown in FIG.
Is separated from the main body part 31a and the switch part 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, the stacking tray 5 pushes the arm portion 31b, and the switch portion 31c is pushed, the state becomes ON. The rotation of the drive motor 34 is stopped.

Further, referring to FIG. 3, description will be given of a guide structure when the stacking tray 5 is moved up and down.

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

Next, with reference to FIGS. 5, 6 and 7, the structure of the pickup roller 6 which is a paper feeding means and the operation at the time of paper feeding, and the trailing edge passage detection sensor which is a feature of this embodiment. The configuration of 60 and the operation control of the pickup roller 6 based on the detection signal of the trailing edge passage detection sensor 60 will be described in detail.

First, FIG. 5 shows a rear end passage detection sensor 60.
In the detailed configuration diagram of 61, 61 is a rotating roller as a rotating member, including a core 61a, a roller 61b made of a rubber material, and a disc 61.
The disk 61c is formed with holes 61d as light-transmitting portions at equal intervals at equal intervals. A rotary shaft 62 rotatably supports the rotary roller 61 and is fixedly supported by the holder 63. Further, 64 is a light transmission type photo sensor having a light receiving part, which is fixed to the holder 63 and
The rotation of 1c is detected. The trailing edge passage detection sensor 60 is rotatably supported by the apparatus main body (not shown) through the hole 63a of the holder, and is attached to the upper surface of the sheet original by its own weight according to the height of the uppermost sheet of the sheet original S. I'm riding.

Then, the roller 61 is rotated by the frictional force received from the sheet document S in response to the conveyance operation of the sheet document S, so that the disc 61c is also rotated, and accordingly, the sensor 64 is provided with the hole 61d. And a light-shielding portion formed by a portion without a hole alternately outputs a Hi / Low signal according to the light-receiving cycle in which the light-receiving portion receives light.
Send to PU50.

FIG. 6 is an upper perspective view showing a drive structure for the vertical movement of the pickup roller 6. The pickup roller 6 is rotatably attached to an arm 72, and the arm 72 is rotatably attached to a shaft 73. It is installed. Further, the pickup roller 6 can be rotated by the driving force of the driving motor 76 via the driving belts 74 and 75. Further, the rotation of the arm 72 is controlled by the rotation support lever 77.
However, it is rotatable about a shaft 78, and the rotation support lever 77 is rotated to rotate by pushing up the E portion. The rotation support lever 77 can be rotated by a stepping motor 80 via a drive belt 79.

With the above structure, the pickup roller 6
The rotation supporting lever 77 pushes up the arm 72 upwards by the rotational driving of the stepping motor 80, and the rotation supporting lever 77 is lowered to the standby position separated from the sheet document S, and the pickup roller 6 moves above the sheet document S. It is possible to switch to the paper feeding position in contact with. Further, at the paper feed position of the pickup roller 6, the drive motor 76 is driven to rotate the pickup roller 6,
The sheet document S is sent out from the top sheet. Here, as described above, the trailing edge passage detection sensor 60 is located on the upstream side of the pickup roller 6 in the conveyance direction of the sheet document S, and in the approximate center in the width direction of the sheet document S orthogonal to the conveyance direction. It is provided.

The trailing edge passage detection sensor 60 is set to the sheet document S.
In the case where the sheet original S is conveyed at the center in the width direction of the sheet original S, the rotating roller 6 is always placed at the center of the sheet original S in the width direction regardless of the size of the sheet original S.
1 abuts. 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, where the upper part shows Hi / Low of the output signal of the trailing edge passage detection sensor 60, and the lower part shows the position of the pickup roller 6. ing.

First, when the preceding sheet original S is being conveyed by the conveying force of the separating portion 7 or the pulling roller 8 or the like, the output signal of the trailing edge passage detection sensor 60 is F (time) in the figure. Up to Hi / Low are repeated at equal intervals. Then, when the trailing edge of the preceding sheet document S passes through F (time), the signal output becomes constant,
At F (time), it can be detected that the trailing edge of the preceding sheet document S has passed the trailing edge passage detection sensor 60.

Then, based on the detection, the CPU 50 sends the stepping motor 80 at G (time) after a certain time.
A rotation command is issued to the pickup roller 6, and the rotation of the motor 80 causes the pickup roller 6 at the standby position to start descending toward the sheet feeding position and land on the next sheet document S at H (time). Here, the rear end is the rear end passage detection sensor unit 6
The sheet original S that has passed 0 has passed through the pickup roller 6 by H (time), and the pickup roller 6 does not contact the sheet original S that is being conveyed.

Further, at I (time) after a fixed time, the CPU 50 issues a rotation command to the drive motor 76, the pickup roller 6 rotates, the next sheet original S is conveyed, and the output signal of the sensor is Again, Hi / Low is repeated at equal intervals. Then, at the time J (time) when the leading edge of the next sheet document S reaches the paper detection sensor (not shown) located downstream of the separation unit 7, the CPU 50 causes the stepping motor 80 to move.
A rotation command is issued to the pickup roller 6, and the rotation of the motor 80 causes the pickup roller 6 at the sheet feeding position to start moving upward toward the standby position and return to the standby position at K (time) to prepare for the next sheet feeding operation. Here, the rotation drive of the drive motor 76 is stopped at K (time) when the pickup roller 6 returns to the standby position.

Next, with reference to FIGS. 8, 9 and 10, the configuration of the separating section 7 which is the separating and conveying means and the operation during the separating and conveying, and the trailing edge passage detection sensor which is the feature of the present embodiment. The operation control of the separation unit 7 based on the detection signal of 60 will be described in detail.

First, the structure of the separating unit 7 will be described.
The front side plate 121, the rear side plate 122, and the paper guide lower part 128 are fixed by screws, respectively, and form a frame body of the separating portion 7. Feeding roller 117 as a forward rotating member
The feeding roller shaft 117a is attached to the front side plate 121 and the rear side plate 12.
2 is rotatably supported via a bearing (not shown).

Further, the separating belt 11 as a reverse rotating 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 by 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 by the belt drive shaft 118a via a bearing (not shown). Further, the separation belt 118 hits an abutting portion (not shown),
It is arranged so as to invade the feeding roller 117 by a predetermined intrusion amount F.

On the other hand, a roller gear 123 and a belt gear 125 are integrally attached to one ends of the feeding roller shaft 117a and the belt drive shaft 118a on the front side plate 121 side, respectively, and an idler gear 124 is rotatably attached to the front side plate 121 therebetween. It is 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. As a result, when the separation belt 118 is rotationally driven in the direction of arrow A (reverse rotation direction for returning the sheet document S), the feeding roller 117
Is rotated in the forward rotation direction for feeding the sheet document S in the transport direction. Therefore, the sheet original S to be conveyed on the side of the feeding roller 117 is fed and conveyed in the direction of the arrow B in the figure by the feeding roller 117, and the other sheet originals S are returned by the separation belt 118, so that one sheet is conveyed. Separately conveyed.

Next, the fixed support structure of the separating portion 7 will be described. The front side plate 121 and the rear side plate 122 respectively include
Round holes 121a, 122a and round elongated holes (front side plate 121
The side is provided with 121b, and the rear side plate 122 side is provided (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 frame body 132 by caulking. The fixed support unit 130 is fixed to the other frame 131 with screws.

Here, the support unit 130 will be described in more detail. Reference numeral 134 is a case of the support unit 130, and 135 is a lid, which are 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 pressure spring 138 is inserted between the lid 135 and the handle 137 to press the fixed support shaft 136 toward the separating portion 7. Due to these, the separating portion 7 is configured such that the round hole 121a,
122a and round elongated holes 121b, 122b (front side plate 1
21 side is 121b, rear side plate 122 side is not shown), fixed shaft 133 and slide fixed support shaft 136, respectively.
Is inserted, and is supported in a state of being pressed toward the fixed shaft 133 by the slide fixed support shaft 136 which is pressed by the pressure spring 138 in the arrow E direction.

Further, the rotation driving section 140 of the separating section 7 will be described. As shown in FIG. 10, reference numeral 141 denotes a drive motor, which uses a stepping motor that has almost no time lag in terms of electrical control. The shaft 141a has a drive gear 14
2 is integrally attached, and the gear holder 144 is rotatably attached via a bearing (not shown). The gear holder 144 has a swing gear 143 that is rotatably attached to a swing gear shaft 145 so as to fit the drive gear 142. Furthermore, 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, the abutting portion 125b of the belt gear 125 and the abutting portion 143b of the rocking gear 143 abut against each other, so that the gear portions 125a and 143a can be engaged with each other while maintaining a proper axial distance, and the driving force can be accurately transmitted. To do.

Here, the drive control of the separation unit 7 will be described. In order to open a predetermined space between the sheet originals, the rear end of the sheet originals is a separation pair (feed roller 1
The driving of the sheet original S is stopped when the sheet original S is sandwiched between the sheet document S 17 and the separation belt 118), and thereafter, the sheet document S is pulled by the pull-out roller pair 9 and the conveying roller pairs 9, 10, 11 on the downstream side.
Need to be transported.

It is because if the pickup roller 6 conveys two or more sheet originals S to the separating section 7 while continuing to drive, the first sheet original S is separated into the separating section 7.
This is because the second sheet document S is also conveyed without exiting the sheet interval after passing through the sheet.

Therefore, the trailing edge passage detection sensor 60 detects that the trailing edge of the sheet original S has passed, and the CPU 50 calculates the time for the trailing edge of the sheet original S to pass through the separating portion 7 to calculate the sheet original. Immediately before the rear end of S passes through the separating portion 7, a predetermined distance (for example, about 10 mm) is applied to the separating portion 7.
Drive motor 14 so that it stops when it is pinched by
Stop control of 1.

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

With the above-described configuration and operation control, the trailing edge of the sheet material passes through the trailing edge passage detection sensor 60 regardless of the length of the transported sheet original S in the transporting direction, and then the separating portion. Since it is possible to accurately grasp the time until the sheet passes through 7, it is possible to minimize the distance for pulling out the sheet original in any length of the sheet original. Slip can also be reduced, and high-productivity sheet conveyance becomes possible.

Further, by using a stepping motor as the drive motor 141 of the separating section 7, there is no electrical time lag when the driving is stopped, and the drive is applied until just before the trailing edge of the sheet document leaves the separating section 7. Therefore, the slip can be further reduced.

(Second Embodiment) In the first embodiment, the case where the sheet material conveying device is applied to feed the sheet original of the image reading device has been described as an example, but a known copying machine, printer or the like. It is also possible to apply the sheet material (recording paper or the like) on which the image of the image reading apparatus is formed to a conveying apparatus for sending the sheet material to the image forming unit at an image forming timing.

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

However, in the present embodiment, the recording sheet S as the sheet material on the stacking tray 5 which is the sheet material stacking section is directly separated and conveyed by the separating section 7, and therefore, as in the first embodiment. The separating unit 7 has the function of a simple sheet feeding unit.

As shown in the figure, based on the image information sent from the outside, the laser light having the image information is supplied to the laser light source 1.
Fire from 51 toward the image forming unit 152.

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

Then, in the present embodiment, as in the first embodiment described above, it is confirmed that the trailing edge of the recording paper S has passed over the stacking tray 5 located upstream of the separating section 7. A trailing edge passage detection sensor 60 is provided as detection means for detecting. Then, the trailing edge of the recording sheet S is detected,
By controlling the drive stop of the separation unit based on this detection,
The same effect as that of the above-described first embodiment can be obtained.

(Third Embodiment) FIG. 12 shows a third embodiment of the present invention. In the first embodiment described above, the separating section 7 of the automatic document feeder, which is a sheet material conveying device, is configured to use a comb-teeth separation system in which a feeding roller and a separation belt are arranged in a comb-teeth shape. But,
In this embodiment, a so-called retard system is adopted. Since other configurations and operations are the same as those of the first embodiment, the same components are designated by the same reference numerals and the description thereof will be omitted.

FIG. 12 is a schematic block diagram of the vicinity of the separating section 7. As shown in the figure, the separating section 7 separates and conveys by the retard method. Separation and conveyance by the retard method is publicly known, and therefore details thereof will be omitted. However, the sheet material S is separated and conveyed one by one by the feed roller 181 and the retard roller 182.

Also in this embodiment, similarly to the above-described first embodiment, it is confirmed that the trailing edge of the recording paper S has passed on the stacking tray 5 located upstream of the separating section 7. Rear end passage detection sensor 60 as detection means for detecting
Is provided. Then, by detecting the trailing edge passage of the recording paper S and controlling the drive stop of the separation unit based on this detection, the same effect as in the above-described first embodiment can be obtained.

(Fourth Embodiment) FIG. 13 shows a fourth embodiment of the present invention. In the first embodiment described above, the separating section 7 of the automatic document feeder, which is a sheet material conveying device, is configured to use a comb-teeth separation system in which a feeding roller and a separation belt are arranged in a comb-teeth shape. But,
In this embodiment, a so-called separation pad system is adopted. Since other configurations and operations are the same as those of the first embodiment, the same components are designated by the same reference numerals and the description thereof will be omitted.

FIG. 13 is a schematic block diagram of the vicinity of the separating section 7. As shown in the figure, the separation unit 7 separates and conveys by a separation pad. Separation and conveyance by the separation pad method is publicly known, and therefore the details thereof will be omitted.
Is configured to be separately conveyed.

Also in this embodiment, similarly to the above-described first embodiment, it is confirmed that the trailing edge of the recording paper S has passed on the stacking tray 5 located upstream of the separating section 7. Rear end passage detection sensor 60 as detection means for detecting
Is provided. Then, by detecting the trailing edge passage of the recording paper S and controlling the drive stop of the separation unit based on this detection, the same effect as in the above-described first embodiment can be obtained.

[0080]

The sheet material conveying apparatus of the present invention is provided with the detecting means for detecting the passage of the trailing end of the conveyed sheet material on the upstream side of the separating and conveying means in the conveying direction. Regardless of the length of the material in the conveying direction, it is possible to accurately grasp the time from the trailing edge of the sheet material passing through the detecting means to the separating and conveying means. The detection accuracy is improved, and the drive stop timing of the separating and conveying means is controlled based on this detection signal, so that the processing speed can be increased.

On the basis of the detection signal of the detection means, before the trailing edge of the sheet material fed in the conveying direction has passed through the nip portion between the forward rotation member and the reverse rotation member constituting the separation conveyance means, and If the control means controls the rotation of the forward rotation member and the reverse rotation member after receiving the conveyance force from the conveyance means, the conveyance can be performed while keeping the distance between the sheet materials to a predetermined value.

When the sheet material is continuously conveyed,
After a lapse of a predetermined time when the trailing edge of the preceding sheet material is detected by the detection means, the sheet feeding operation of the next sheet material is performed by the sheet feeding means, and it is confirmed that the sheet material is separated and conveyed by the separating and conveying 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.

The forward rotation member and the reverse rotation member can transmit the rotary drive having excellent control characteristics by transmitting the rotary drive force by the stepping motor.

If the detecting means is provided so as to be able to come into contact with the conveyed sheet material of the sheet material stacked in the sheet material stacking portion,
The sheet material stacking unit can detect passage of the rear end of the conveyed sheet material.

The detecting means includes a light transmitting portion that rotates by the frictional force received from the conveyed sheet material and that 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 portion for receiving the transmitted light, the rotating member having a rotating member is provided, and when the conveyed sheet material passes, the rotation of the rotating member stops and a change in the light receiving cycle occurs. It can detect that the rear end has passed.

If the detecting means is provided substantially at the center in the width direction of the sheet orthogonal to the sheet conveying direction, it is possible to prevent the skew of the sheet original.

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

[Brief description of drawings]

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

FIG. 2 is a schematic configuration diagram showing an elevating operation of a stacking tray included in the image reading apparatus according to the first embodiment of the present invention.

FIG. 3 is a top view of the stack tray of FIG.

FIG. 4 is a conceptual diagram of a paper surface height sensor mounted on the stacking tray of FIG.

FIG. 5 is a schematic configuration diagram of a trailing edge passage detection sensor included in the image reading apparatus according to the first embodiment of the present invention.

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

FIG. 7 is a conceptual graph showing the output signal of the trailing edge passage detection sensor and the position of the pickup roller.

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

9 is a cross-sectional view showing a supporting state of the separation portion of FIG.

FIG . 10 is an upper perspective view of a drive unit that drives a separation unit included 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]

1 Image reading device 2 Document reading section 3 Automatic document feeder 5 loading tray 6 Pickup roller 7 Separation part 8 Pull-out roller pair 50 CPU 60 Rear end passage detection sensor 61 rotating roller 61c disc 61d hole 62 rotation axis 64 Light-transmitting photo sensor 117 Feed roller 118 separation belt 141 drive motor (stepping motor) 150 printers 151 laser light source 152 image forming means 181 Feed roller 182 retard roller 191 Conveyor roller 192 Separation Pad

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-3-67836 (JP, A) JP-A-5-24714 (JP, A) JP-A-5-105279 (JP, A) JP-A-61- 33437 (JP, A) JP 60-128138 (JP, A) JP 59-102740 (JP, A) Actual flat 2-69679 (JP, U) Actual flat 2-13046 (JP, U) Furukaihei 3-44137 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B65H 3/06 B65H 3/52 G03G 15/00

Claims (9)

(57) [Claims] 1. A sheet feeding means for feeding sheet materials stacked in a 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, detection means provided upstream of the separating and conveying means in the conveying direction, for detecting passage of the rear end of the conveyed sheet material, and the detecting means. A sheet material conveying device, comprising: a control means for controlling a drive stop timing of the separating and conveying means based on a detection signal of the means. 2. The separating / conveying means includes a forward rotating member that feeds the sheet material fed by the sheet feeding means in a conveying direction and a sheet material that is fed while being overlapped with the forward rotating member. A reverse rotation member that rotates in the direction of returning to the direction, and a drive unit that drives the forward rotation member and the reverse rotation member, the control unit based on the detection signal of the detection unit,
The forward-rotating member and the reverse-rotating member before the rear end of the sheet material fed in the conveying direction passes through the sandwiching portion between the forward-rotating member and the reverse-rotating member and after receiving the conveying force from the conveying means. The sheet material conveying device according to claim 1, wherein the driving means is controlled so as to stop the rotation of the member. 3. The control means, when the sheet material is continuously conveyed, after a predetermined time after the detection means detects that the trailing edge of the preceding sheet material has passed, the control means performs the next feeding operation by the paper feeding means. 3. The sheet material feeding operation according to claim 1, wherein the sheet feeding operation by the sheet feeding means is stopped after confirming that the sheet material has been separated and conveyed by the separating and conveying means. The sheet material conveying device described in. 4. The sheet material 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 detecting means is provided so as to be capable of contacting a sheet material conveyed by the sheet material stacked in the sheet material stacking section. Sheet material conveying device according to item 1. 6. The light detecting means is rotated by a frictional force received from a conveyed sheet material, and cuts off the light from a light transmitting portion which transmits light emitted in a direction parallel to the rotation axis. A light receiving portion for receiving the transmitted light is provided, and a passage of the rear end of the sheet material conveyed is detected from a light receiving cycle of receiving light by the light receiving portion. The sheet material conveying device according to claim 5. 7. The sheet material conveying device according to claim 1, wherein the detecting means is provided substantially at the center in the width direction of the sheet orthogonal to the sheet conveying direction. 8. An image reading apparatus comprising reading means for reading an original image of an original 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 unit for forming an image on a sheet material conveyed by the sheet material conveying apparatus according to claim 1. Description: