JPH10181948A - Sheet material transport device, image reading device, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable sheet material transporting apparatus, an image reading apparatus, and an image for properly transporting a sheet material by correcting skew of the transported sheet material and correcting the distance between the sheet materials. A forming device is provided. SOLUTION: The time when the trailing edge of a document n passes each sensor is the same, and the first count-up of the counter is started from the time when the trailing edge passes (C). First, the front surface sensor detects the leading edge of the document n + 1, thereby attaining the HI level (D). At that time, the count value B becomes the first count value corresponding to the interval between the document n and the document n + 1. It stops and restarts the second count-up.
Thereafter, when the front depth sensor detects the leading edge of the document n + 1, the level becomes the HI level (E), and the count value A at that time is obtained.
Becomes the second count value corresponding to the skew amount of the document n + 1, and the counting operation is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a sheet conveying apparatus provided in an image reading apparatus such as a scanner, a copying machine, a facsimile apparatus, and an image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, this type of sheet conveying apparatus has been used as an apparatus for feeding a document to an image reading section for reading an image of the conveyed document in an image forming apparatus such as a copying machine.

Such a sheet conveying apparatus generally has a function of correcting skew of a document. For example, a pair of transport rollers that rotate independently in the left and right directions in the width direction perpendicular to the transport direction, a pair of sensors that detect the amount of skew of the document are provided, and the transport rollers are responsive to the skew of the document detected by the sensor pair. The skew of the document has been corrected by changing the rotation speed of each motor for rotating the pair.

[0004]

However, in the case of the prior art as described above, attention is paid only to the skew amount of the original document detected by the sensor pair, and the conveying roller pair is rotationally driven in accordance with the skew amount. The skew was corrected by changing the rotation speed of each motor.

That is, when the sheet material is skewed and conveyed, the speed of each of the conveying rollers provided on the left and right in the width direction is temporarily changed from a predetermined speed (in the width direction of the sheet material). Of the slower side, or
Or, the speed of the leading side is reduced), and the skew is corrected.

As described above, since the skew correction is performed without considering the distance between the sheet materials of the continuously conveyed sheet materials, the distance between the sheet materials is equal to the initially set sheet material. It became wider or narrower than the distance between the materials.

[0007] If such an error occurs in the distance between the sheet materials, a deviation occurs in the image reading timing or the image forming timing, and the speed of the sheet material conveyance process is hindered. .

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 correct skew of a conveyed sheet material and correct the distance between the sheet materials so as to appropriately perform the correction. It is an object of the present invention to provide a sheet material conveying device, an image reading device, and an image forming device that are excellent in conveying a sheet material.

[0009]

In order to achieve the above object, according to the present invention, there are provided first members which are provided at different positions in the direction perpendicular to the sheet conveying direction and which can independently convey the sheet members. A first detecting means and a second detecting means which are respectively provided at different positions in the direction perpendicular to the conveying direction of the sheet material and independently detect the passage of the sheet material, Recognition means for recognizing a conveyance state of a conveyed sheet material based on comparison information between each of the passage detection times detected by the first detection means and the second detection means and a preset target time. And control means for independently controlling the transport speeds of the first transport means and the second transport means based on the transport state of the sheet material recognized by the recognition means. .

Therefore, the recognizing means recognizes the transport state of the sheet material from comparison information between the respective passage detection times detected by the first detecting means and the second detecting means and a preset target time. Therefore, a detailed transport state is recognized.

The target time may be set to a time from when the trailing edge of the preceding sheet material passes through the leading edge of the later sheet material of the two normally transported sheet materials.

The first conveying means and the first detecting means are provided on one side of a center line with respect to the width perpendicular to the conveying direction of the sheet material, and the second detecting means is provided on the other side of the center line. Preferably, a transporting means and a second detecting means are provided.

[0013] The recognizing means determines a skew direction of the sheet material based on a comparison between the passing time of the sheet material detected by the first detecting means and the passing time of the sheet material detected by the second detecting means. And a first calculating means for calculating the skew amount.

Therefore, the skew direction is determined based on the speed of the passing time, and the skew amount is calculated based on the difference between the compared passing times.

The second means calculates an error in the interval between the sheet material conveyed immediately before, based on a comparison between the passing time of the sheet material detected by each of the detecting means and the target time. May be provided.

Therefore, an error in the interval between the sheet and the sheet conveyed immediately before is calculated based on a difference between the passing time and the target time.

[0017] The control means may determine whether the passage time of the sheet material detected by the first detection means and the passage time of the sheet material detected by the second detection means are both later than the target time. The transport speed of one of the first transport unit and the second transport unit is temporarily determined based on the skew direction and the skew amount calculated by the first calculation unit. It is better to control the speed to be faster than the speed.

Accordingly, the skew is corrected while reducing the error in the interval between the sheet and the sheet conveyed immediately before.

[0019] The control means may determine whether the passage time of the sheet material detected by the first detection means and the passage time of the sheet material detected by the second detection means are both earlier than the target time. The transport speed of one of the first transport unit and the second transport unit is temporarily reduced from a predetermined speed based on the skew direction and the skew amount calculated by the first calculating unit. Should also be controlled to slow down.

Therefore, the skew is corrected while reducing the error in the interval between the sheet and the sheet conveyed immediately before.

The control means may determine that one of the passage time of the sheet material detected by the first detection means and the passage time of the sheet material detected by the second detection means is earlier than the target time, and the other is Is longer than the target time, based on the skew direction and the skew amount calculated by the first calculation means, one of the first conveyance means and the second conveyance means It is preferable that the transport speed is temporarily made lower than the predetermined speed and the transport speed of the other transport means is temporarily made higher than the predetermined speed.

Therefore, the skew is corrected while reducing the error in the interval between the sheet and the sheet conveyed immediately before.

When the interval between the sheet and the sheet conveyed immediately before, which is calculated by the second calculating unit, is larger than a normal interval, the control unit may control the first unit based on the calculation result. The transport speed of at least one of the transport unit and the second transport unit may be controlled to be temporarily higher than a predetermined speed.

Accordingly, an error in the interval between the sheet and the sheet conveyed immediately before is corrected.

If the interval between the sheet and the sheet conveyed immediately before, which is calculated by the second calculating means, is smaller than a normal interval, the control means determines the first value based on the calculation result. The transport speed of at least one of the transport unit and the second transport unit may be controlled to be temporarily lower than a predetermined speed.

Therefore, an error in the interval with the sheet material conveyed immediately before is corrected.

[0027] The control means changes the transfer speed and the change rate of the transfer speed of each of the first transfer means and the second transfer means based on the calculation results of both the first calculation means and the second calculation means. It is advisable to determine the period of time.

Therefore, the skew and the error in the distance between the sheet conveyed immediately before are corrected simultaneously.

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

The image forming apparatus may be provided with an image forming means for forming an image on the sheet conveyed by the sheet conveying apparatus.

[0031]

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 11 show a first embodiment of the present invention.

FIG. 1 is a schematic cross-sectional configuration diagram of a flow-reading scanner, which is an image reading device, provided with a sheet conveying device according to the first embodiment of the present invention.

A case in which the sheet conveying apparatus according to the present embodiment is applied to an apparatus for feeding a document as a sheet will be described below.

In FIG. 1, reference numeral 101 denotes a document feeder serving as a sheet conveying device; 102, a scanner main body;
Is a document stacking tray, 104 is a lifter driving motor for the document stacking tray, 105 is a feeding roller, 106 is a separation roller, 107 is a pull-out roller, and 108, 109, and 11.
Reference numerals 0, 111, and 112 denote vertical path conveying rollers, 113 denotes a front surface reading / pulling roller, 118 denotes a back surface reading / pulling roller, 114 and 115 denote a double-sided paper discharging path conveying roller,
116 and 117 are reverse path conveying rollers, 119 is a paper discharge roller, 132 is a discharged document stacking tray, 120 is a skew correction roller for reading the front, 121 is a skew correction roller for reading the back, 127 is a document illumination lamp, 128 is a lens,
129 is a CCD linear image sensor for image reading,
A position 133 between the skew feeding correction rollers 120 and 121 is a moving image reading position, and 130 is a paper sensor.

FIG. 2 is a schematic configuration diagram of a main part (flow reading part) viewed from above.

Here, the front and rear skew correction rollers 120, 1
As shown in FIG. 2, reference numeral 21 denotes a skew correction roller 120 which is disposed one by one on the back side and serves as a conveying means on the front side.
(Skew correction roller 120-1 as the first conveyance means and skew correction roller 120-2 as the second conveyance means) Skew by changing the rotation speed of motors 201 and 202 as the driving sources. The correction is performed, and the skew amount is determined by the sensor 203 as the first detection unit and the sensor 2
Detection is performed based on the detection time difference at 04.

On the back side, a motor 205 which is a driving source of each of the skew correction rollers 121 (the skew correction rollers 121-1 as the first conveying means and the skew correction rollers 121-2 as the second conveying means). , 206 is changed, the skew amount is detected, and the amount of skew is detected by the detection time difference between the sensor 207 as the first detecting means and the sensor 208 as the second detecting means.

Here, the skew correction rollers 120 and 12 are used.
1, two sensors 203, 204, 207, and 208 are arranged on the upstream side and the downstream side in the transport direction as detection means for detecting the document transported by the printer 1. However, the present invention is not limited to this. Alternatively, a configuration may be adopted in which original detection is performed using a CCD or the like. In addition, although a pulse motor as a driving unit that rotationally drives the skew feeding correction rollers 120 and 121 is illustrated, the invention is not limited thereto.

FIG. 3 shows a main part (double-sided conveyance path 13) in FIG.
4) is a schematic configuration diagram of FIG.

At the time of double-sided reading, the original whose front side has been read is conveyed to the double-sided conveyance path via the backside skew correction roller 121, and conveyed by the conveyance rollers 113, 116, and 117, and then again the backside skew correction roller 121. The image is conveyed to the image reading position 133 through which the image on the back side is read, and is ejected via the two-sided ejection path conveyance rollers 114 and 115.

The two thick lines in FIG.
The originals n and n + 1 (in the order of conveyance) are shown.
At the moment when the trailing end of the document has passed through the backside skew correction roller 121, the document n and the document n + 1 are transported in the direction of the arrow in the figure, Y is the distance between the transport sheets of the document n and the document n + 1, and X is the document n And the original n + 1, and the distance between X and the original n
The skew correction roller 121 must be reversed (from the arrow A to the arrow B in the figure) to change the transport direction while the document is transported. Is determined from

As the sheet interval Y becomes narrower, the distance of X becomes wider, so that there is a margin between the passing of the document n and the document n + 1 and the reversing time of the backside skew correction roller 121. There is no room, and the paper interval cannot be detected, so that a stagnant jam is apt to occur. As the paper interval X becomes narrower, the distance of Y becomes wider and the space between the papers becomes larger.
There is no longer enough time for the reversal and the reversing time of the backside skew correction roller 121, and after the rear end of the document n + 1 after reading the front side has passed the backside skew correction roller 121, the backside skew correction roller 121 starts to be reversed. Before returning to the steady speed of the back side reading, the leading end of the document n
, And the manuscript is easily damaged.

Therefore, the range of both X and Y is limited, and the document must be conveyed, especially in the double-sided conveyance path, so that the sheet interval does not exceed the range.

As shown in FIG. 4, the document detection sensor 20
The information detected by 3, 204, 207, and 208 is calculated by a counter unit 4 as a calculating unit that constitutes a recognizing unit that calculates the skew direction and the skew amount of the document from the detected information.
01. In the counter unit 401, the skew direction of the document is binary information of “1” or “0”, which is information indicating which side is skewed toward the near side. The time until the other sensor detects the document is counted at a certain clock frequency f, and this count value is defined as the skew amount of the document. Then, the skew direction and the skew amount of the document calculated here are transmitted to the CPU 402 which is a control unit of the apparatus.

The CPU 402 stores the information on the skew direction and the skew amount of the document calculated as described above in the memory unit 403 serving as storage means, and stores the skew direction and the skew information stored in the memory unit 403. The skew displacement direction and the skew displacement amount are calculated from the row amount. The motor driving pulse (driving frequency) is varied based on the skew displacement direction and the skew displacement amount so that the document conveying speed of the skew correction rollers 120 and 121 is constant on both sides in the width direction. , 202,2
05 and 206 are controlled.

FIG. 5 is a state diagram of the movement of the skew feeding correction roller and the original when the skew feeding is corrected before the front surface reading, as viewed from above.

In FIG. 5A, before the correction is started, the front side skew correction motor 201 and the back side skew correction motor 202 rotate the skew correction rollers 120-1 and 120-2 at the same speed, and the leading edge of the original is corrected. Waiting for the sensors 203 and 204 to arrive, when the front and rear sensors detect the leading edge of the document, the skew direction and skew amount information are calculated.

In FIG. 5B, the driving frequency of the front-side skew correction motor 201 and the rear-side skew correction motor 202 is changed based on the information on the calculated skew direction and skew amount. The skew correction is started by changing the rotation speed of 1, 120-2.

The following three methods can be used to change the driving frequency.

1) One of the skew correction rollers on the front side is rotated at a steady speed, the rotation speed of the other skew correction roller is reduced, and the speed is returned to the steady speed again.

2) One of the skew correction rollers on the front side is rotated at a steady speed, the rotation speed of the other skew correction roller is increased, and the speed is returned to the steady speed again.

3) The rotation speed of one of the skew correction rollers at the front is reduced, and the rotation speed of the other skew correction roller is increased.
Return to steady speed again.

In FIG. 5C, after the skew correction is completed, the front skew correction motor 201 and the back skew correction motor 202 are set.
Rotates the skew correction rollers 120-1 and 120-2 at the same speed, and conveys the document to the reading unit.

FIG. 6 is a diagram showing the relationship between the skew sensor input and the counter before the front side reading.

In the figure, reference numeral 601 denotes the state of the terminal of the front surface sensor 203. When the document is not on the sensor, the level is LOW, and when the document is on the sensor, the level is HI. H
N and n + 1 at the I level indicate the preceding document n and the following document n + 1, respectively.
The falling edge to the level represents the trailing edge of the preceding document n, and the rising edge from the LOW level to the HI level represents the leading edge of the following document n + 1. Reference numeral 602 also indicates the state of the terminal of the surface depth sensor 204.

In the figure, reference numerals 603 and 604 denote time and the counter unit 4.
01 indicates the relationship between the count values inside, 603 indicates the skew amount measurement, 604 indicates the sheet interval measurement, and the time axis (horizontal axis) corresponds to both sensor terminal states 601 and 602.

Since the skew correction is performed on the rear end of the document n before image reading, the time for the rear end to pass through each of the sensors 203 and 204 is the same, and the first count-up of the counter is started from the time when the rear end passes. Is started (time C in the figure). In this figure, since the front end of the document n + 1 is conveyed ahead of the front side, the front sensor 203 detects the front end of the document n + 1 first to be at the HI level (time D in the figure) and the count value B at that time. Becomes the first count value corresponding to the sheet interval between the document n and the document n + 1, temporarily stops counting up, and starts second counting up again. Thereafter, when the front depth sensor 204 detects the leading edge of the document n + 1, the level becomes HI (time E in the figure), the count value A at that time becomes the second count value corresponding to the skew amount of the document n + 1, and the counting operation is stopped. I do.

This figure shows a document of interest (here, document n).
FIG. 13 is a diagram illustrating the operation of the counter when there is a preceding document (here, document n) before +1). If there is no preceding document before the target document, the first counting operation is not performed.

Here, the sheet interval and the skew amount are not counted by the counter 401, but the sensor output is directly sent to the CPU 402.
May be connected to the input terminal and counted in the CPU 402.

Next, with reference to FIG. 7, a description will be given of the drive control of the paper transport system having the above-described configuration, focusing on the original n + 1 at the time of reading the front side.

When it is detected that the trailing edge of the preceding document n has passed through the front or back sensor (S1), the counter 401 performs the first counting operation to measure the sheet interval between the document n and the document n + 1. The process starts (S2), and waits until the leading edge of the leading side of the document n + 1 conveyed by the skew feeding correction rollers 120-1 and 120-2 is detected by the front surface front or back sensor on the leading side ( S3) When detected, the skew direction of “1” or “0” is obtained as described above (S3).
4) The first count operation is stopped (S5), and the count value at this time is obtained as a sheet interval count value (S6), and the document n
A second count operation for measuring the skew amount of the front end of +1 is started (S7), and the front end of the trailing side of the document is waited until the front surface front or back sensor detects the trailing end ( S
8) When detected, the second count ends simultaneously with the detection of the trailing edge (S9). The count value at this time is obtained as a skew count value (S10).

This operation is performed by the front surface sensor 203, the front depth sensor 204, and the counter 401, and the obtained skew direction, skew amount, and sheet interval information are transmitted to the CPU 402.

The CPU 402 converts the preset target sheet interval into a count value (corresponding to the target time), stores it in the memory unit 403, and counts the sheet interval count value received by the above-described method in the following order. Compare.

First, of the front sensor 203 and the front sensor 204, the side on which the original is detected first (the leading side)
Then, the count value (inter-sheet count value) is compared with the target inter-sheet count value (S11). Hereinafter, the leading side count value corresponds to the leading side detection time, the trailing side count value corresponds to the trailing side detection time, and the target sheet interval count value corresponds to the target sheet interval (target time).

If the leading side count value is equal to or larger than the target sheet interval count value, the sheet is conveyed by a sheet interval larger than the target sheet interval (the sensor 203 is delayed with respect to the target time). 204), so that the rotational speed of the skew correction roller on the preceding side is not changed in order to match the paper interval after correction with the preceding side, and the skew on the side detected later (the succeeding side) is not changed. Skew correction is performed by increasing the rotation speed of the correction roller (S12).

If the preceding count value is smaller than the target inter-sheet count value, the process proceeds to the next step, in which the front-side sensor 203 and the front-side depth sensor 204 which have detected the document later (the following Side) and the target sheet interval count value (S13).

If the trailing side count value is equal to or smaller than the target sheet interval count value, the sheet is conveyed by a sheet interval smaller than the target sheet interval (the sensors 203 and 204 are faster than the target time). Skew on the previously detected side (leading side) without changing the rotation speed of the skew correction roller on the trailing side in order to match the corrected paper interval with the trailing side. Skew correction is performed by lowering the rotation speed of the correction roller (S14).

Next, when the succeeding count value is larger than the target sheet interval count value, the process proceeds to the next step. In such a case, the leading side is transported by a sheet interval smaller than the target sheet interval (reaches one of the sensors 203 and 204 faster than the target time), and the succeeding side is a sheet interval larger than the target sheet interval. Between the sensors 203 and 204, which are later than the target time, so that the amount of one preceding part and the amount of the other following part are calculated as follows.
It is necessary to adjust in consideration of the measured position and the like.

In this embodiment, the passage time is measured at a position equidistant from the center line with respect to the width perpendicular to the conveying direction of the sheet material, so that the time measured by the sensors 203 and 204 is Average is sensor 20
Since this corresponds to the time when the center in the width direction of the sheet material passes on the straight line connecting the sensor 3 and the sensor 204, it is necessary to compare this time with the target time.

That is, the (sheet interval count value + skew count value / 2) is compared with the target sheet interval count value (S1).
5).

If these are equal to each other including the decimal point, the rotation speed of the preceding skew correction roller is reduced, and the rotation speed of the subsequent skew correction roller is increased to perform skew correction (S16). . At this time, by adjusting the rotation speed so that the skew correction amount on the leading side is equal to the skew correction amount on the subsequent side, the corrected sheet interval becomes equal to the target sheet interval.

If (sheet interval count value + skew count value / 2) is not equal to the target sheet interval count value including the decimal part, (sheet interval count value + skew count value / 2)
Is compared with the target sheet count value (S17).

If the target sheet interval count value is larger, the skew correction amount on the preceding side (lower speed side) is larger than the skew correction amount on the succeeding side (higher speed side). The skew correction is performed by decreasing the rotation speed of the row correction roller and increasing the rotation speed of the skew correction roller on the trailing side (S18).

If the target inter-sheet count value is smaller, the skew correction amount on the preceding side (high-speed side) is larger than the skew correction amount on the preceding side (low-speed side). Skew correction is performed by lowering the rotation speed of the row correction roller and increasing the rotation speed of the skew correction roller on the trailing side (S19).

In this way, the sheet interval after the skew correction becomes equal to the target sheet interval.

Next, a correction method realized by the above-described flowchart will be described.

The relationship between the sensor terminal state and the target sheet when the state transitions to S12 in FIG.
In the figure, reference numeral 801 in the figure denotes the state of the terminal of the front surface sensor 203. When the document is not on the sensor, the level is LOW, and when the document is on the sensor, the level is HI. N and n + 1 at the HI level indicate the preceding document n and the following document n + 1, respectively. The falling edge from the HI level to the LOW level indicates the preceding document n.
And the rising edge from the LOW level to the HI level indicates the leading edge of the next original n + 1.
Reference numeral 802 similarly indicates the state of the terminal of the surface depth sensor 204.

The theoretical time derived from the target sheet interval from the trailing edge of the document n to the leading edge of the next document n + 1 in 803, that is, between the sheets when the document n and the document n + 1 are normally conveyed. The corresponding ideal transit time is shown.

These front and back sensors 801 to 803 detect the document first by the front surface sensor 203 of the skewed document.
Reference numeral 4 indicates that the theoretical time derived from the target sheet interval is earlier than the time when the original is detected later and the original is later detected.

In this case, the rotation speed described in the state S12 is changed by maintaining the rotation speed of the front skew correction roller 120-1 on the front front sensor 203 side at the reading speed (FIG. 8 ( b) Medium 804), surface depth sensor 204
The rotation speed of the skew correction roller 120-2 on the side is increased for a fixed time by the amount for correcting the skew amount (80 in FIG. 8C).
The skew correction is performed by changing the drive frequency of the drive motors 201 and 202 as described in 5). A hatched portion 806 in FIG. 8C corresponds to a correction amount.

Similarly, the relationship between the sensor terminal state and the target sheet when the state transitions to S14 in FIG. 7 is represented by the horizontal axis as time, and FIG. 9A is used, and 901 to 903 indicate the oblique surface of the original. The front sensor 203 detects the document first, and the front depth sensor 2
Numeral 04 indicates that the theoretical time derived from the target sheet interval is later than the time when the original was detected later and the later time when the original was detected.

In this case, the rotation speed described in the state S14 is changed by maintaining the rotation speed of the front-side skew correction roller 120-2 on the side of the front-side depth sensor 204 at the reading speed (FIG. 9 ( c) middle 905), front surface sensor 203
The rotation speed of the front-side front skew correction roller 120-1 is reduced for a fixed time by an amount to correct the skew amount (90 in FIG. 9B).
The skew correction is performed by changing the drive frequency of the drive motors 201 and 202 as described in 4). A hatched portion 906 in FIG. 9B corresponds to a correction amount.

Further, the relationship between the state of the sensor terminal and the target sheet when the state transitions to S16 in FIG.
The reference numerals 1001 to 1003 denote the time when the front side sensor 203 of the skewed document first detects the document, the front side sensor 204 detects the document later, and the front side sensor 203 detects the document and the front side depth. This represents a case where the time corresponding to the midpoint of the time when the sensor 204 detects the document coincides with the theoretical time derived from the target sheet interval.

In this case, the change of the rotation speed described in the state S16 is, for example, when the skew correction amount is 2 × (mm), the front skew correction roller 12 on the front sensor 203 side.
The method of lowering the rotation speed of 0-1 is t1 × S1 where t1 (sec) is the time during which the rotation speed is reduced, and S1 (mm / sec) is the difference speed between the read speed and the low speed. = X (mm) (the skew correction amount is the shaded area 1006 in FIG. 10B), t1 and S1 are determined, respectively, and the rotation of the front skew correction roller 120-2 on the front depth sensor 204 side How to increase the speed is t2 (sec), the time while increasing the rotation speed,
Assuming that the difference speed between the reading speed and the rotation speed when the rotation speed is high is S2 (mm / sec), t2 × S2 = X (mm) (the skew correction amount is represented by a hatched portion 1007 in FIG. 10C). T2 and S2 are determined respectively, and the rotational speeds are changed so that the skew correction amounts are equal to each other and are corrected by X (mm) (1004 and 104 in FIGS. 10B and 10C).
05).

Further, the relationship between the sensor terminal state and the target paper at the time of the state transition to S18 in FIG. 7 is expressed in FIG. 11 (a) with the horizontal axis representing time, and 1101 to 1103 represent the front side of the skewed original. The case where the sensor 203 detects the document first, the theoretical time derived from the target sheet interval becomes α hours after the document detection, and then the front depth sensor 204 detects the document after β hours (where α <β) is there).

In this case, the change of the rotation speed described in the state S18 is such that the correction amount on the low-speed correction side is smaller than the correction amount on the high-speed correction side. If the skew correction amount at this time is Y (mm), the correction amount on the low-speed correction side = (α / (α + β)) × Y The correction amount on the high-speed correction side = (β / (α + β)) × Y (α <Β), and as shown in FIG. 11B, the method of reducing the rotation speed of the front surface skew correction roller 120-1 on the front surface sensor 203 side is such that the time during which the rotation speed is reduced is t1 (sec), S1 is the difference speed between the reading speed and the speed when the rotation speed is low.
If (mm / sec), the hatched portion 1106 in the hatched portion in FIG. 11B becomes the skew correction amount, so that t1 × S1 = (α / (α + β)) × Y (mm) (α <β) T1 and S1 are determined so that
By using (c), the rotation speed of the surface depth skew correction roller 120-2 on the surface depth sensor 204 side can be increased by increasing the rotation speed by t2 (sec) and increasing the rotation speed with respect to the reading speed. If the speed difference at the time is S2 (mm / sec), 1107 in the hatched portion in FIG. 11C is the skew correction amount, so that t2 × S2 = (β / (α + β)) × Y (mm) T2 and S2 are determined so that (α <β), and the rotation speed is changed such that the respective skew correction amounts are in the ratio of α: β (α <β) (FIG. 11B, (C) Medium 1004,1
005).

The state S19 in FIG. 7 corresponds to α in FIG.
> Β, and as in the state S18, the change of the rotation speed means that the skew is corrected so that the correction amount on the low-speed correction side <the correction amount on the high-speed correction side, and t1 × S1 = (α / (Α + β)) × Y (mm) (α> β) t2 × S2 = (β / (α + β)) × Y (mm) (α> β) The rotation speed is changed so that the skew correction amount has a ratio of α: β (α> β).

The same processing is performed in the case where the front-side sensor detects the front end of the document before the front-side sensor detects the original, and also in the skew correction on the back side.

In the present embodiment, the speed change is performed in one stage, but the speed may be changed by slowing up or slowing down the speed in a stepwise manner.

As described above, the skew is not corrected in consideration of only the skew direction and the skew amount of the conveyed sheet material, but the target derived from the normal interval (target paper interval) between the sheet materials. Since the skew correction is also performed in consideration of the time (theoretical time), the error in the interval between the sheet materials can be corrected with the skew amount as a limit, and the sheet conveyance accuracy is improved.

(Second Embodiment) FIGS. 12, 13 and 14 show a second embodiment of the present invention. In the first embodiment, the skew of the sheet material is corrected in a direction in which the error is reduced in consideration of the error in the distance between the sheet materials, and the error is corrected with the skew amount being limited. However, the present embodiment is configured to completely correct the error. 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.

In the above-described first embodiment, the correction of the error in the distance between the sheet materials is limited to the amount of skew of the sheet materials. That is, in the case shown in FIG. 8 described above as an example, the amount of skew (the difference between the rises of 801 and 802) is corrected and corrected until the rise of 801. Is still not resolved,
In the present embodiment, the configuration is such that the error is completely corrected. This is particularly effective when, for example, the image forming unit or the image reading position is located sufficiently away from the position where the skew feeding is corrected.

FIG. 12 is a top view of the place where skew correction is performed. The front front skew correction roller and the front back skew correction roller are 1201 and 1202, respectively, and the drive motors are 1205 and 1206. The front-side skew sensor and the front-side skew detection sensor for detecting the skew direction and the skew amount of the sheet to be conveyed are 1203 and 1204, respectively. Reference numeral 1208 denotes a preceding sheet (n) for which skew correction has been completed, and reference numeral 1207 denotes a sheet (n + 1) for which skew correction is to be performed.
FIG. 12 is a diagram viewed from the top, showing a state in which a sheet interval time derived from the target sheet interval has elapsed after the rear end of the preceding sheet 1208 has passed through the skew detection sensors 1203 and 1204.

FIG. 13 is an enlarged view of a main part of FIG. 12, wherein A is the distance between sheets derived from the target sheet, and B is the distance between sheets.
(A + B) is the actual sheet interval, and C represents the amount of skew on the front side and the back side of the sheet.

The states of FIGS. 12 and 13 correspond to the position of D in FIG. 14A, where the horizontal axis represents time, and A ', B', and C 'in FIG. The values when the expressed distances A, B, and C are respectively converted into time are shown.

Here, when the same method as that of the first embodiment is employed, after the skew correction, the time interval B '(in terms of distance B) of the target sheet interval is left. I will. Therefore, in order to approach the target paper by the distance B, the front skew correction roller 1201 and the front skew correction roller 1201 are used.
2 must be higher than the steady speed, and FIG. 14B shows the relationship between the rotation speed and the time of the front oblique skew correction roller 1202 and the front oblique skew correction roller 1202 at this time. 14) and FIG.

In FIG. 14B, reference numeral 1404 denotes the rotational speed of the front oblique skew roller. From the state of the front front sensor terminal 1401 in FIG. Instead, the rotational speed is increased by the difference between the target papers and the paper after the skew correction. Since the difference in this case is B, the correction amount 1407 is represented by B = SP1 × t1.

In FIG. 14C, reference numeral 1405 denotes the rotation speed of the front-side skew roller. From the front-side sensor terminal state 1402 in FIG. The rotation speed is increased by the difference B between the target sheets after the skew correction with respect to the target sheet. In this case, the correction amount 1406,
1408 are represented by C = SP2 × t3 B = SP2 × t2, respectively, and C + B = (SP2 × t3) + (SP2 × t2) includes the paper interval correction by increasing the rotation speed of the oblique roller 1201. This is the correction amount.

As described above, by increasing the rotation speed of each of the front skew roller and the front skew roller so as to perform the above-described correction, the skew correction is performed, and at the same time, the space between the preceding sheet and the preceding sheet is increased. Can be corrected between the target sheets (correction of the error in the distance between the sheet materials).

The case where the interval between the sheet materials has become larger than the ideal interval (normal interval) has been described with reference to FIG. 14. On the contrary, the interval between the sheet materials is smaller than the ideal interval. If it becomes smaller, the rotation speed can be reduced by the correction amount in the same manner as described above to correct the error in the distance between the sheet materials.

(Other Embodiments) In the above embodiment, the driving frequency of the pulse motor for driving each roller is changed based on the calculated skew direction, skew amount, sheet interval and target sheet interval. Although the skew or the paper interval is corrected, the drive source is not limited to this.

If the actually measured sheet interval or the interval obtained by adding the skew amount to the sheet interval with respect to the target sheet interval is an interval at which the sheet cannot be transported smoothly, a warning is displayed to the operator and the transport is stopped. The configuration may be such that:

Further, in the above-described embodiment, the document feeder provided with the reading mechanism for reading the image of the conveyed document is exemplified as the sheet material conveyer to which the present invention is applied, but the present invention is not limited to this. Instead, for example, a copier,
In an image forming apparatus such as a facsimile apparatus, the present invention may be applied to a sheet material conveying unit that sends a document as a sheet material to an image reading unit or a sheet material conveying unit that sends a recording medium as a sheet material to an image forming unit. The same effect as the above effect can be obtained.

[0105]

According to the present invention, the recognition of the sheet material is performed based on comparison information between the passage detection times detected by the first detection means and the second detection means and a preset target time. Since the transport state is recognized, a detailed transport state is recognized, and the transport is controlled by the control means based on the recognized detailed transport state, so that transport with excellent accuracy can be realized and reliability is improved.

If the target time is set to the time from when the trailing edge of the preceding sheet material passes through the leading edge of the later sheet material of the two normally transported sheet materials, the distance between the sheet materials can be reduced. Can be corrected so as to make the distance of the image data appropriate.

By providing the first calculating means, the passing time of the sheet material detected by the first detecting means is compared with the passing time of the sheet material detected by the second detecting means. The skew direction is determined by the speed,
The skew amount can be calculated from the difference between the transit times.

By providing the second calculation means, the error of the interval between the sheet material conveyed immediately before is calculated from the comparison between the passage time of the sheet material detected by each detection means and the target time. it can.

By the control means, comparison with the target time,
By the conveyance control based on the skew direction and the skew amount calculated by the first calculating means, the skew can be corrected while reducing the error in the interval between the sheet material conveyed immediately before.

The control means can correct the error in the interval with the sheet material conveyed immediately before by the conveyance control based on the calculation result by the second calculation means.

The control means controls the conveyance control based on the calculation results of both the first calculation means and the second calculation means to determine the skew and the error in the interval between the sheet material conveyed immediately before. It can be corrected at the same time.

The above-described highly reliable sheet material transporting apparatus having excellent transporting accuracy can be applied to an image reading apparatus having a reading unit or an image forming apparatus having an image forming unit.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional configuration diagram of an image reading apparatus provided with a sheet material conveying device according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a main part of FIG. 1 as viewed from above.

FIG. 3 is a schematic configuration diagram of a main part of FIG. 1;

FIG. 4 is a block diagram showing a configuration of a control system of the image reading apparatus according to the first embodiment of the present invention.

FIG. 5 is a top view of the skew feeding correcting operation of the sheet conveying apparatus according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between a sensor input and a counter in FIG. 4;

FIG. 7 is a flowchart illustrating skew correction control of the sheet conveying apparatus according to the first embodiment of the present invention.

FIG. 8 is a control diagram in a predetermined state in the flowchart in FIG. 7;

FIG. 9 is a control diagram in a predetermined state in the flowchart in FIG. 7;

FIG. 10 is a control diagram in a predetermined state in the flowchart in FIG. 7;

FIG. 11 is a control diagram in a predetermined state in the flowchart in FIG. 7;

FIG. 12 is a top view of a skew feeding correction unit of the sheet conveying apparatus according to the second embodiment of the present invention.

FIG. 13 is an enlarged view of a sheet interval and a sheet detection unit of the sheet conveying apparatus according to the second embodiment of the present invention.

FIG. 14 is a control diagram of a predetermined state in the sheet conveying apparatus according to the second embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 101 Document feeder 102 Scanner body 103 Document loading tray 114, 115 Double-sided discharge path transport roller 116, 117 Reverse path transport roller 119 Discharge reverse roller 120 Skew correction roller for front reading 121 Skew correction for back reading Rollers 201 to 206 Drive motors 203, 204, 207, 208 for performing skew correction skew amount detection sensor 401 Counter unit 402 CPU 403 Memory unit

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hirokazu Kodama Canon Inc. 3- 30-2 Shimomaruko, Ota-ku, Tokyo

Claims (13)

[Claims] A first conveying means and a second conveying means which are respectively provided at different positions in a direction perpendicular to a sheet material conveying direction and which can independently convey the sheet material; A first detection unit and a second detection unit that are respectively provided at positions in different directions and independently detect the passage of the sheet material; and each of the first detection unit and the second detection unit that are detected by the first detection unit and the second detection unit. Recognition means for recognizing the transport state of the conveyed sheet material based on comparison information between the passage detection time and a preset target time, and based on the transport state of the sheet material recognized by the recognition means, A sheet transporting device comprising: a controller configured to independently control the transport speeds of the first transporter and the second transporter. 2. The method according to claim 1, wherein the target time is set to a time from a time when a rear end of a preceding sheet material of the two normally conveyed sheets passes to a time when a front end of a subsequent sheet material passes. The sheet material conveying device according to claim 1, wherein: 3. The first conveying means and the first detecting means are provided on one side of a center line with respect to the width perpendicular to the conveying direction of the sheet material, and the first detecting means is provided on the other side of the center line. 3. The sheet conveying apparatus according to claim 1, further comprising a second conveying unit and a second detecting unit. 4. The sheet recognizing means according to claim 1, wherein said recognizing means compares the transit time of the sheet material detected by the first detecting means with the transit time of the sheet material detected by the second detecting means. 4. The sheet conveying apparatus according to claim 1, further comprising a first calculating unit that calculates a row direction and a skew amount. 5. The recognition means calculates an error in the interval between the sheet material conveyed immediately before, based on a comparison between the passage time of the sheet material detected by each of the detection means and the target time. 5. The sheet conveying apparatus according to claim 1, further comprising a second calculating unit. 6. The control means according to claim 1, wherein the passage time of the sheet material detected by the first detection means and the passage time of the sheet material detected by the second detection means are both later than the target time. If there is, based on the skew direction and the skew amount calculated by the first calculation means, the transfer speed of one of the first transfer means and the second transfer means is temporarily set. 5. The sheet conveying apparatus according to claim 4, wherein control is performed such that the speed is higher than a predetermined speed. 7. The control means according to claim 1, wherein said sheet material passage time detected by said first detection means and the sheet material passage time detected by said second detection means are both earlier than said target time. The transport speed of one of the first transport unit and the second transport unit is temporarily determined based on the skew direction and the skew amount calculated by the first calculation unit. The sheet conveying apparatus according to claim 4, wherein the control is performed such that the speed is lower than the speed. 8. The control means, wherein one of a passage time of the sheet material detected by the first detection means and a passage time of the sheet material detected by the second detection means is earlier than the target time. If the other is later than the target time, one of the first transport unit and the second transport unit is determined based on the skew direction and the skew amount calculated by the first calculation unit. 5. The sheet material according to claim 4, wherein the conveying speed of the conveying means is controlled to be temporarily lower than a predetermined speed, and the conveying speed of the other conveying means is temporarily set to be higher than the predetermined speed. Transport device. 9. The controller according to claim 6, wherein the controller calculates the distance based on the calculation result when an interval with the immediately preceding sheet material calculated by the second calculator is larger than a normal interval. 6. The control device according to claim 5, wherein the control unit controls the transport speed of at least one of the first transport unit and the second transport unit to be temporarily higher than a predetermined speed.
The sheet material conveying device according to item 1. 10. The method according to claim 1, wherein the controller calculates the distance based on the calculation result when the interval between the sheet and the sheet conveyed immediately before calculated by the second calculator is smaller than a normal interval. The sheet conveying apparatus according to claim 5, wherein the conveying speed of at least one of the first conveying means and the second conveying means is controlled to be temporarily lower than a predetermined speed. . 11. The control unit according to claim 1, further comprising: a control unit configured to change a transport speed of each of the first transport unit and the second transport unit based on a calculation result of the first and second calculation units. 11. The sheet conveying apparatus according to claim 4, wherein a period to be changed is determined. 12. An image reading apparatus, comprising: reading means for reading a document image of a sheet conveyed by the sheet conveying apparatus according to claim 1. Description: 13. A sheet material conveyed by the sheet material conveying device according to any one of claims 1 to 12,
An image forming apparatus comprising an image forming means for forming an image.