JPH04164748A - Sheet feed/delivery device - Google Patents

Abstract

PURPOSE:To detect multiple sheet feed regardless of the thickness or type of the sheet by applying certain load which works in a rotating direction with a load means which is provided in the driven roller of a pair of delivery rollers to deliver sheet to downstream after separating the sheet with a separating means. CONSTITUTION:The material of a pair of delivery rollers 15 is selected so that friction coefficient mu1, mu3 between a driving side, driven side rollers 15a, 15b, and a sheet document 2 may become larger than friction coefficient mu2 between the sheet documents 2, 2. The pressing force of the driven side roller 15b is set as N. The relation of the delivery force Nmu1 of sheet document 2 of the driving side roller 15a, force Nmu3 for the sheet document, 2 to rotate the driven side roller 15b, circumferential force F of load applied to the driven roller 15b through a spring 20, and delivery force Nmu2 to the sheet document 2 of the sheet document 2 is set as follows Nmu1>=Nmu3>F>Nmu2. The side which comes into contact with the driving side roller 15a of multiply fed sheet document 2 is delivered, but the side which comes into contact with the driven side roller 15b is not rotated due to load F and stayed at the position. Then multiple feed is detected from a difference between rotary encoders 16, 17 of the pair of delivery rollers 15.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a sheet feeding device included in an image reading device or an image forming device such as a facsimile machine or a copying machine.

(II) Conventional Technology A sheet feeding device provided in an image reading device or an image forming device is of a type that separates and feeds a large number of stacked sheets (transfer paper, etc.) one by one. However, it is difficult to reliably separate and feed the sheets one by one due to the type (material) of the sheet, changes in sheet characteristics due to the usage environment, changes over time (for example, deterioration) of the device, and the like.

Therefore, as a supplementary measure, double feeding by the sheet feeding device is detected, and based on this detection, various problems caused by double feeding in the device etc. are prevented.

Conventionally, a typical method for detecting double feeding by a sheet feeding device is to detect the thickness of sheets after separation.

(c) Problems to be Solved by the Invention However, in the case of the conventional method of detecting electrical feeding by a sheet feeding device by detecting the thickness of sheets after separation, there is There was a problem in that if sheets of different thickness were mixed, the detection would not occur even if the sheets were fed in duplicate. Also, even if the stacked sheets that you are trying to feed this time are of the same thickness, if you try to feed a sheet of a different thickness next time, you will have to readjust the detection level. Problems may occur if the Furthermore, in order to detect a very small amount of sheet thickness, a magnifying mechanism is required, and the magnifying mechanism is complicated and large.

Therefore, the present invention has been made in view of the above-mentioned circumstances, and it is possible to reliably detect double feeding of sheets regardless of the type and thickness of the sheets to be fed, and furthermore, it is possible to It is an object of the present invention to provide a sheet feeding device that can be easily constructed and requires a small installation space.

(Means for Solving the Problems) In order to achieve the above object, the present invention, for example, as shown with reference to FIGS. 1 and 2, a large number of stacked sheets (
2) relates to a sheet feeding device that separates and feeds sheets one by one.

The present invention also provides a drive-side roller (15a) that is rotationally driven by an external driving force, and a drive-side roller (15a).
) is in contact with a predetermined pressure and rotates as a driven roller (15b).
), and a load provided on the driven roller (15b) of the conveying roller pair (15) that conveys the separated sheet (2) downstream by the separating means (7). The means (19, 20, 21) apply a constant load acting in the rotational direction, and the separating means (7) separates the separated sheet (2) or the conveying roller pair (15).
A pair of conveying rollers (15) or a sheet (2) when conveyed by
) is characterized by detecting the state of.

Further, the sheet (2
) or the difference in rotational speed between the drive side roller (15a) and the driven side roller (15b) of the conveyance roller pair (15) when conveyed by the conveyance roller pair (15). It is something.

Further, when the sheet (2) separated by the separating means (7) is transported by the transport roller pair (15), the loop (
2a).

Furthermore, the drive side roller (15) of the conveyance roller pair (15)
a) is disposed on the same side as the sheet feeding side (7a) of the separating means (7) with respect to the sheet conveying surface, and the driven side roller (15b) of the conveying roller pair (15) is disposed on the same side with respect to the sheet conveying surface. The separating means (7) is located on the same side as the non-sheet feeding side (7b).

(E) Effect According to the above configuration, when the sheet (2) after a minute Wl is fed double by the separating means (7), the conveying roller pair (15)
The load applied to the driven roller (15b) of the sheet (
2, 2) If the size is large enough to overcome the frictional force of the same dirt floor, slipping may occur between the double-fed sheets (2, 2) when conveyed by the pair of conveyance rollers (15), and only one sheet may slip. It will be conveyed by the drive roller (15a). In this case, the rotational speeds of the driving side roller (15a) and the driven side roller (15b) of the conveying roller pair (15) each change. Further, the sheet (2) whose conveyance is prevented by the driven roller (15b) forms a loop on the upstream side of the pair of conveying rollers (15) by the continuous feeding operation by the separating means (7).

Therefore, the state of the conveying roller pair (15) when the sheet is conveyed by the conveying roller pair (15) (drive side roller (
15a) and the driven roller (15b)) or the state of the sheet (2) (the loop formed on the upstream side of the transport roller pair (15)). is detected.

Note that the above reference numerals in parentheses are used to refer to the drawings, and do not limit equivalent configurations.

b) Example An embodiment of the present invention will be described below based on the drawings.

<First Embodiment> FIG. 1 shows the overall configuration of an image reading device equipped with a sheet feeding device according to the first embodiment of the present invention, and FIG. 2 shows the overall configuration of the same sheet feeding device. It is.

In the figure, the reference numeral 1 denotes a document tray on which a large number of sheet documents are stacked, and the reference numeral 3 denotes a lever for pushing up the document tray 1 upward by a push-up blade of a spring 5.

Reference numeral 6 is a paper feed roller that feeds the original 2, and reference numeral 7 is a separation means consisting of a feed roller 7a and a separation roller 7b. The feed roller 7a is composed of a plurality of rollers (see FIG. 2), and is attached to the shaft 10 via a one-way clutch 9.

The shaft 10 is connected to a drive system (not shown) via a clutch 11. Further, the shaft 10 and the shaft 12 of the paper feed roller 6 are connected by a gear train (not shown). The feed roller 7 and the paper feed roller 6 each rotate counterclockwise in FIG. Like the feed roller 7a, the separation roller 7b is composed of a plurality of rollers (see FIG. 2), and is rotated counterclockwise by receiving driving force from a shaft 13 or a drive system (not shown). Each feed roller 7a and each separation roller 7b are provided so as to be located between each other. By adjusting the distance between the axes of each feed roller 7a and each separation roller 7b to an appropriate position, the sheet originals 2 sent by the paper feed roller 6 are separated one by one.

Reference numeral 15 denotes a pair of conveying rollers for conveying the sheet originals 2 separated one by one by the separating means 7 downstream. This conveyance roller pair 15 includes a drive-side roller 15a that is rotationally driven by obtaining driving force from a drive system (not shown), and a drive-side roller 15a that is rotationally driven by receiving driving force from a drive system (not shown).
and a driven roller 15b that rotates as a result of contact with the roller a at a predetermined pressure. These driving side roller 15a and driven side roller 1
Rotary encoders 16 and 17 that generate pulses in response to rotational motion are attached to one end of each of the rotary encoders 5b.

A plate member 1 that can slide only in the axial direction is attached to the driven roller 15b.
9 is installed. This plate member 19 has a spring 20 connected to a friction member 21 fixed to a frame (not shown).
is pressed by. As a result, the driven roller 1
A constant load is applied to 5b in the direction of rotation.

This load is set to be larger than the frictional force between the sheet originals 2.2, as will be described later. The plate member 19, the spring 20, and the friction member 21 constitute a load means.

The sheet feeding roller 6, separating means 7, and conveying roller pair 15 constitute a sheet feeding device. In this sheet feeding device, the feed roller 7a of the separating means 7 and the driving roller 15a of the conveying roller pair 15, and the separating roller 7b of the separating means 7 and the driven roller 15b of the conveying roller pair 15 are on the same side with respect to the document conveying surface. It is necessary to be placed in the The reason will be explained later.

Reference numeral 22 is a sensor for detecting the sheet original 2. Reference numeral 23.25 is a pair of conveying rollers, and reference numeral 26.2 is a pair of conveying rollers.
7 is a conveyor belt. The conveyor belts 26 and 27 sandwich the sheet document 2 and convey it to the paper discharge section 29.

Reference numeral 30 denotes an optical unit that includes an illumination lamp 31, a mirror 32, an imaging lens 33, and an image reading sensor 35, and reads the back side of the sheet original 2. Moreover, the code 36 is
This optical unit is composed of an illumination lamp 37, a mirror 39, an imaging lens 40, and an image reading sensor 41, and reads the surface of the sheet original 2. Reference numeral 42 is a recording device for recording images read by the optical unit 30.36, and reference numeral 43 is a display device for displaying the image read by the optical unit 30.36 and other necessary information.

Next, the operation of this sheet feeding device will be explained.

The sheet document 2 on the document tray 1, which is pressed against the paper feed roller 6 by a predetermined four pressures by the lever 3 biased by the spring 5, is fed into the apparatus by the paper feed roller 6 and rotates counterclockwise. The paper sheets are separated one by one by a separating roller 7b and sent to a nip portion between a pair of transport rollers 15.

Then, when the sheet document 2 is detected by the document detection sensor 22, the clutch 11 is disengaged, and the drive of the paper feed roller 6 and the feed roller 7a is disengaged. Thereafter, the sheet document 2 is sent to the paper discharge section 29 via the transport roller pair 15 by the transport roller pair 23.25 and the transport belt 26.27.

On the other hand, the paper feed roller 6 and the feed roller 7a rotate in conjunction until the sheet document 2 passes, or the one-way clutch 9
Due to this action, the paper feed roller 6 stops rotating when the sheet document 2 passes through the paper feed roller 6. That is, after the sheet original 2 passes through the paper feed roller 6, while the sheet original 2 passes through the feed roller 7a, the paper feed roller 6 does not rotate even if the feed roller 7a rotates in conjunction with the feed roller 7a. After the trailing edge of the sheet original 2 passes the paper feed sensor 22, the clutch 11 is activated again to rotate the paper feed roller 6 and the feed roller 7a, and feed the next original 2. Start feeding.

In the above-described feeding operation, if the sheet documents 2 are not separated properly and double feeding occurs, the double feeding sheets are sent to the next pair of conveying rollers 15 in a double feeding state. Here, the friction coefficient between the driving roller 15a of the transport roller pair 15 and the sheet original 2 is μ2, and the ** coefficient between the sheet originals 2 and 2 is μ2.
2. Sheet original 2 and driven roller 1 of transport roller pair 15
The material of the conveyance roller pair 15 (driving side roller 15a, driven side roller 15b) is selected so that μ, ≧μ3>μ2, where μ is the coefficient of friction of the roller 5b. Also, the pressing force of the driven roller 15b against the driving roller 15a is set to N.
, further, let F be the force in the circumferential direction of the driven roller 15b of the load applied to the driven roller 15b.

Nμm is the conveying force of the driving roller 15a on the sheet original 2, Nμ2 is the conveying force of the sheet original 2 on the sheet original 2, and Nμ is the force of the sheet original 2 trying to rotate the driven roller 15b. These relationships are Nμm≧Nμ, >Nμ2. At this time, if F is selected such that Nμm≧Nμ, >F>Nμ, the sheet document 2 on the side in contact with the driving roller 15a is transported by the rotation of the driving roller 15a, or the sheet document 2 on the driven side The sheet document 2 on the side in contact with the roller 15b is placed on the driven side roller 1.
If the roller 5b is rotated against the load F, it will slip between the sheet originals 2.2 and the driven roller 15bflll.
The sheet original 2 of ll will remain in place. Therefore, there is a difference in the number of pulses generated from the rotary encoders 16 and 17 attached to the driving roller 15a and the driven roller 15b. By detecting this difference, it can be determined whether double feeding has occurred or not.

Here, Nμm and Nμ3 can be determined by appropriately selecting the materials of the driving roller 15a and the driven roller 15b.
It is possible to make it sufficiently larger than μ2. Further, F can be made sufficiently larger than Nμ2 by appropriately selecting the material of the friction plate 21 or the spring force of the spring 20. That is, Nμm≧Nμ, >>F:>
It is possible to more reliably detect double feeding, which is Nμ2.

Figure 3 shows the rotary encoder 16.1 of the sheet feeding device.
7 is a block diagram illustrating a double feed detection circuit that detects double feed by detecting a difference between pulses generated from 7 to 7. FIG.

Pulses from rotary encoders 16 and 17 attached to the driving roller 15a and the driven roller 15b are sent to pulse counters, respectively. Pulse counter 45
, 46 divide the sent pulses at fixed time intervals and count them, and calculate the values by the successive approximation circuit 4.
Send to 7.

If there is a certain difference between the sent values, the comparison calculation circuit 47 sends that signal to the CPU. Based on the sent signal, the CPU 49 recognizes that double feeding has occurred in the sheet feeding device, and issues a signal to the image reading device to take appropriate measures.

Here, the arrangement of the above-mentioned feed roller 7a and separation 7a, drive side roller i5a and driven side roller 15b will be explained. Normally, when the sheet originals 2 are fed in duplicate, the sheet original 2 on the side that is in contact with the separation roller 7b is delayed, and the reverse is not possible. Therefore, contrary to the illustrated case, if the roller 15b is the driving side and the roller 15a is the driven side, then as shown in FIG. At the same time, the leading edge of the sheet document 2 may be applied to the rear (downstream) transport roller pair 23. At this time, the sheet original 2 is transported by the transport force of the transport roller pair 23, and the roller 15a rotates in conjunction with this, and the sheet original 2 cannot be stopped. Therefore, double feeding of the sheet 2 cannot be detected without finding the rotation difference between the rollers 15a and 15b.
The positional relationship between the paper and the document transport surface is important.

Second Embodiment FIG. 5 shows a sheet feeding device according to a second embodiment of the present invention. While the first embodiment described above detects the double feeding of the sheet 2 by the method of detecting the state of the transport roller pair 15, this embodiment detects the double feeding of the sheet 2 by the method of detecting the state of the sheet 2. This shows the case where transmission detection is performed.

In the sheet feeding device of this embodiment, the feeding roller 7a,
Separation roller 7b, drive side roller 15 of conveyance roller pair 15
a. The driven roller 15b has exactly the same construction as in the first embodiment.

Similarly, a constant load is applied to the driven roller 15b in the rotational direction. In this embodiment, a loop detection sensor 52 consisting of a microswitch or the like for detecting the loop 2a of the sheet 2 is installed between the separation roller 7b and the driven roller 15b on the document conveyance path 51. .

In such a sheet feeding device, if the double-fed sheet original 2.2 is now conveyed by the rollers 15a and 15b, the friction of the sheet original 2.2 rotates the roller 15b as described above. Since the load applied to roller 15b is greater than the force applied to roller 15b, roller 15b
tries to hold one (upper) sheet original 2 without rotating. Since this sheet original 2 is pushed from behind, it forms a loop 2a as shown in the figure. this loop 2
The actuator 52a of the loop detection sensor 52 consisting of a micro switch or the like is pushed by the loop 2a.
By detecting this, it is detected whether the sheet originals 2 are being fed multiple times.

As shown in FIG.
When the conveyance roller pair 53 is provided on the downstream side of
It is possible to reliably form the loop 2a of the sheet original 2. Therefore, the detection performance of the loop 2a is high, and the performance as a means for detecting double feeding of sheet documents is also high.

FIG. 7 shows a double feed detection circuit according to a third embodiment.

In the sheet feeding device of the first embodiment, the driving side roller 15a of the conveying roller pair 15 and the driven side roller pair 15
Whether rotary encoders 16 and 17 were attached to each of sheet document 2 to detect the rotation difference between them.
If the conveyance speed is a predetermined constant value, the rotary encoder 16 attached to the drive-side roller 15a can be omitted, resulting in cost reduction. The double feed detection circuit of this embodiment shows an example of the configuration in this case.

Pulses generated from the rotary encoder 17 are sent to a pulse counter 46 and counted at fixed time intervals. The value is then sent to the successive approximation circuit 47. On the other hand, a signal is sent from the CPU 49 to the decoder 50 based on the transport speed that is determined at that time. A comparison calculation circuit 47 compares the respective signals, and if the value from the pulse counter 46 is smaller than a certain value, the signal is sent to the CPU.
Send to 49. The CPU 49 thereby recognizes the occurrence of electrical transmission.

(g) As described in detail of the invention, the sheet feeding device of the present invention includes a driving side roller that is rotationally driven by an external driving force, and a driven side that is in contact with the driving side roller with a predetermined pressure and rotates as a result. A load means provided on the driven roller applies a constant load acting in the rotational direction to the driven roller of the conveying roller pair which conveys the separated sheet downstream by the separating means, and By detecting the state of the conveying roller pair or the sheet when the separated sheet is conveyed by the conveying roller pair by the separation means, it is possible to reliably feed the sheet regardless of the type or thickness of the sheet to be fed. It is possible to detect double feeding of sheets. Further, the double feed detection means in this case can be constructed easily and requires a small installation space.

[Brief explanation of drawings]

Each of the drawings shows an embodiment of the present invention, and FIG. 1 is a longitudinal sectional front view showing the overall configuration of an image reading device equipped with a sheet feeding device according to the first embodiment, and FIG. 2 is an overall view of the same sheet feeding device. FIG. 3 is a block diagram of a double feed detection circuit in the same sheet feeding device, and FIG. 4 is an enlarged perspective view showing the configuration of the sheet feeding device. FIG. 5 is a vertical front view showing a sheet feeding device according to the second embodiment, and FIG. 6 is a vertical front view showing an example in which the performance of double feed detection is further improved in the same sheet feeding device. 7 are block diagrams of a double feed detection circuit according to a third embodiment, in which a part of the double feed detection circuit of FIG. 3 is modified. 2...Sheet original, 2a...Loop, 7.
...Separation means, 7a...Feed roller (sheet feeding side), 7b...Separation roller (non-sheet feeding side)
III), 15... Conveyance roller pair, 15
a... Drive side roller, 15b... Driven side roller,' 16.17 River rotary encoder, 19.
...Plate member, 20...Spring, 21...
Friction member, 52...Loop detection sensor.

Claims (1)

[Claims] 1. In a sheet feeding device that separates and feeds a large number of stacked sheets one by one, a drive-side roller rotationally driven by an external driving force, and the drive-side roller It consists of a driven roller that rotates in contact with the roller under a predetermined pressure.
Loading means provided on the driven roller applies a constant load acting in the rotational direction to the driven roller of the pair of transport rollers that conveys the separated sheet downstream by the separating means, and the separated sheet is conveyed downstream by the separating means. A sheet feeding device characterized in that the state of the conveying roller pair or the sheet is detected when the sheet is conveyed by the conveying roller pair. 2. A difference in rotational speed between a driving roller and a driven roller of the pair of conveying rollers when the separated sheet is conveyed by the pair of conveying rollers by the separating means is detected. Sheet feeding device as described. 3. The sheet feeding apparatus according to claim 1, wherein a loop of the sheet on the upstream side of the conveying roller pair is detected when the sheet separated by the separating means is conveyed by the conveying roller pair. 4. The driving side roller of the conveying roller pair is disposed on the same side as the sheet feeding side of the separating means with respect to the sheet conveying surface, and the driven side roller of the conveying roller pair is disposed on the same side as the sheet feeding side of the separating means with respect to the sheet conveying surface. The sheet feeding device according to claim 1, wherein the sheet feeding device is arranged on the same side as the non-sheet feeding side of the sheet feeding device.