JPH11199096A - Paper conveying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect abnormal conveyance of paper with simple constitution. SOLUTION: Sensors 12, 14 are installed with a interval L along a conveying direction U of paper 90. Elapsed time from the time of the sensor 12 detecting the passage of the paper tip until the time of the sensor 14 deteting the passage of the paper tip is counted by one counter. In the case of the count value being equal to the time of conveying the paper 90 by the interval L portion, the paper 90 is judged not to be skewed, and in the case of the count value being unequal to the time of conveying the paper 90 by the interval L portion, the paper 90 is judged to be skewed. The skew feed of the paper 90 can be accurately detected on the basis of the count value using only one counter without using two counters heretofore in use.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper transport apparatus, and more particularly, to a paper transport apparatus for transporting fixed-size paper to a predetermined position along a predetermined transport path.

[0002]

2. Description of the Related Art Conventionally, there has been proposed a technology for detecting an abnormal conveyance of a sheet such as a document or a recording sheet in an image forming apparatus or the like.

Japanese Patent Application Laid-Open No. Hei 6-278903 describes a technique for detecting double feed of sheets such as originals using two contact sensors. In this technology, various kinds of detection mechanisms such as the size of the paper sheet are realized by contacting the paper sheet in addition to the double feeding of the paper sheet. However, in order to increase the detection sensitivity, the pressure at the contact point is increased. Must be raised. Increasing the pressure at the contact point in this manner may induce skew of the sheet. Note that the skew of the sheet means that the sheet is transported in a predetermined transport direction in an inclined posture. On the other hand, when the pressure at the contact point is reduced, the detection sensitivity is reduced, and chattering (fluttering) of the paper sheet may occur.

A technique for detecting skew of a fixed-size sheet by a non-contact type sensor instead of a contact type sensor as described above,
It is described in Japanese Patent Application Laid-Open No. H7-112849. According to the technique described in this publication, first and second sensors for detecting the passage of the leading edge of a sheet are arranged on a straight line perpendicular to the sheet conveying direction, and a predetermined value is set for the time interval of the detection time by these sensors. When there is the above difference, it is determined that the sheet is skewed.

However, in the above technique, when the leading edge of the sheet passes through the first sensor of the two sensors first, the first sheet is used.
A counter for measuring a time interval from the detection time of the first sensor to the detection time of the second sensor, and detecting the first sensor from the detection time of the second sensor when the leading edge of the sheet passes the second sensor first Total 2 of counters that measure time intervals up to time
Needed two counters.

Therefore, with a simple configuration having a small number of parts,
There has been a long-awaited need for a technique for accurately detecting a sheet conveyance error.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and provides a paper transport apparatus capable of accurately detecting a paper transport abnormality with a simple configuration. The purpose is to:

[0008]

According to a first aspect of the present invention, there is provided a sheet conveying apparatus for conveying a sheet of a fixed size to a predetermined position along a predetermined conveying path. First detecting means for detecting that the leading edge of the sheet has passed a first reference position in a transport path near the predetermined position, and wherein the leading edge of the sheet is perpendicular to the transport direction of the sheet. The first reference position and the first reference position;
Detecting that the vehicle has passed the second reference position in the conveyance path on the downstream side in the conveyance direction by a predetermined distance from the reference position.
Detecting means, time measuring means for measuring an elapsed time from when the leading end of the sheet passes through the first reference position to when passing through the second reference position, and timing obtained by the timing means. Abnormality detecting means for detecting that an abnormality has occurred in the conveyance of the sheet based on the elapsed time and the time required to convey the sheet by the predetermined distance.

Further, in the paper conveying apparatus according to the second aspect,
2. The sheet transport device according to claim 1, wherein the abnormality detecting unit is configured such that the leading end of the sheet passes through the second reference position before the first reference position, and the timing by the timing unit is not performed. 3. And detecting that an abnormality has occurred in the conveyance of the sheet.

According to a third aspect of the present invention, in the paper transport apparatus according to the first or second aspect, when the abnormality detecting means detects that an abnormality has occurred, the predetermined position is determined. The apparatus further comprises control means for stopping conveyance of the sheet to the discharge tray and discharging the sheet to a predetermined discharge tray.

According to a fourth aspect of the present invention, in the paper transport apparatus according to any one of the first to third aspects, when the abnormality detection unit detects that an abnormality has occurred. And a notifying unit for notifying that an abnormality has occurred.

The paper transport device according to the first aspect of the present invention is a paper transport device for transporting a sheet of a fixed size to a predetermined position along a predetermined transport path, for example, an image forming apparatus such as a copying machine or a printer. The present invention is applied to a paper transport device that transports recording paper to a predetermined image recording position, a paper transport device that transports a document to be copied by a copying machine to a predetermined image reading position, and the like.

In such a paper transport apparatus, the first detecting means detects that the leading edge of the paper has passed the first reference position near the predetermined position (ie, the target position of the paper transport).

On the other hand, the second detecting means detects that the leading edge of the sheet is
It is detected that the sheet has passed from the first reference position in a direction perpendicular to the sheet conveyance direction and has passed the second reference position in the conveyance path downstream of the first reference position by a predetermined distance in the conveyance direction. .

Here, for example, the first detecting means and the second detecting means
Detecting means that the sheet is at the reference position (the first reference position, the second reference position,
(The reference position), it is possible to detect that the leading edge of the sheet has passed the reference position by switching from the state where the sheet does not exist to the state where the sheet exists.

The timer measures the elapsed time from when the leading edge of the sheet passes through the first reference position to when it passes through the second reference position.

Here, when the sheet is normally conveyed and passes through the first reference position and the second reference position without skewing, the elapsed time obtained by the timing of the timer means that the sheet travels a predetermined distance ( = Time required to convey by the distance between the first reference position and the second reference position along the paper conveyance direction (hereinafter, referred to as
(Referred to as a transport reference time). On the other hand, when the sheet passes the first reference position and the second reference position while skewing, the elapsed time obtained by the timing of the timing unit is not equal to the transport reference time.

Therefore, the abnormality detecting means detects that an abnormality has occurred in the conveyance of the sheet based on the fact that the elapsed time obtained by the time measurement by the time measuring means is not equal to the conveyance reference time.

As described above, according to the first aspect of the present invention, the two timing means are not used as in the prior art, and the leading end of the sheet is the first.
Using only the timing means for measuring the elapsed time from the passage of the reference position to the passage of the second reference position, and determining that the elapsed time obtained by the timing of the time means is not equal to the transport reference time. It is possible to accurately detect that an abnormality has occurred in the conveyance. That is, it is possible to detect the occurrence of an abnormality in sheet conveyance with high accuracy using fewer components than in the related art.

When the sheet is skewed with a large inclination, the leading edge of the sheet may pass through the second reference position before the first reference position. No timekeeping by means is performed. In other words, there is no data for the elapsed time obtained by the timing of the timing means.

Therefore, if the leading edge of the sheet passes through the second reference position before the first reference position and the time is not measured by the time counting means, it can be clearly considered that an abnormality has occurred in the sheet conveyance, so As described in item 2, it is desirable that the abnormality detecting means immediately detect that an abnormality has occurred in the conveyance of the sheet.

With this configuration, when the inclination of the sheet is large and the leading end of the sheet passes through the second reference position before the first reference position, it is possible to quickly detect the occurrence of an abnormality in the sheet conveyance.

If the abnormality detecting means detects that an abnormality has occurred in the paper conveyance, the control means stops the paper conveyance to a predetermined position. It is desirable to discharge the paper to a predetermined discharge tray. This prevents the sheet from being transported to a predetermined position in a tilted state, and wastes processing (for example, recording an image or reading an image) on the sheet in a tilted state transported to the predetermined position. Can be avoided.

When the abnormality detecting means detects that an abnormality has occurred in the sheet conveyance, the notifying means notifies the operator or the like of the occurrence of the abnormality by the notifying means. Is desirable. This allows
The operator can quickly recognize that an abnormality has occurred in the sheet conveyance, and can promptly execute a countermeasure at the time of the abnormality.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a paper transport device according to the present invention will be described below. Hereinafter, a case in which the paper transport device according to the present invention is applied to the copying machine 10 shown in FIG. 1 will be described.

[Schematic Configuration of Copying Machine 10] As shown in FIG. 1, the copying machine 10 has a substantially rectangular parallelepiped casing 50 and a substantially flat casing 52 disposed above the casing 50 at a predetermined interval. And The casing 52 is supported by one end of a substantially U-shaped support portion 54, and the other end of the support portion 54 is engaged with the lower surface of the housing 50.

The housing 50 has a plurality of casters 56 on the lower surface.
The upper surface is partially cut away to form a face-down tray 58. In addition, housing 5
The face-up tray 60 is attached to the side of the housing 50 at an angle to the side surface of the housing 50.

In the casing 52, a display 64 for displaying various messages and information such as the processing status is provided on the front side of the sheet of FIG. 1, and an operator gives various instructions such as paper size setting and copy start / stop. An operation unit 62 for inputting is provided. Also, the casing 52
An opening / closing lid 66 is attached to the camera so as to be openable and closable along the arrow A direction. A transparent flat glass plate (not shown) is attached to the upper surface of the casing 52 hidden by the opening / closing lid 66. Below the flat glass plate, an original set on the flat glass plate is read. A scanner unit (not shown) is provided.

On the upper surface of the opening / closing lid 66, a plate-shaped mounting tray 68 for mounting an original is mounted diagonally. A document feeder (not shown) is provided inside the opening / closing lid 66, and the document feeder guides the document placed on the loading tray 68 onto the flat glass plate described above. The document on the glass plate is guided to a discharge tray 70 formed on the upper surface of the opening / closing lid 66.

[Sheet Conveying Method in the Present Embodiment] Next, the sheet conveying method in the present embodiment will be described with reference to FIG. In the paper transport system according to the present embodiment, when the paper 90 of the standard size is transported to the recording transfer position, a paper transport belt 18 provided on a transport path and driven and controlled by a control unit 30 (see FIG. 4) described later. After the sheet 90 is once conveyed in an oblique direction (the direction of the arrow W) with respect to the conveyance direction U and the end 90A of the sheet 90 is brought into contact with the sheet conveyance path guard 20, the control section 30 drives the sheet 90 (see FIG. 4). The sheet 90 is transported in the transport direction U by the controlled sheet transport roller 16.

At a first reference position near the target position where the paper 90 is to be conveyed, it is detected whether or not the paper 90 is present at the first reference position. A first sensor 12 for detecting that the tip has passed the first reference position is provided. Also, at a second reference position located downstream of the first reference position by a predetermined distance L along the transport direction U of the paper 90, it is determined whether the paper 90 exists at the second reference position. And a second sensor 14 for detecting that the leading end of the paper 90 has passed the second reference position based on the detection result.

[Apparatus Configuration for Detecting Abnormality in Sheet Conveyance] Next, an apparatus configuration for detecting an abnormality in sheet conveyance will be described with reference to FIG. As shown in FIG. 4, the copying machine 10 is provided with a control unit 30 which is configured by a microcomputer or the like and controls and monitors the operation of various components in the copying machine 10.
The detection signals from the first sensor 12 and the second sensor 14 are input to the control unit 30.

The control unit 30 includes the copying machine 1 described above.
Size detection information from a well-known size detection mechanism 44 for detecting the size of a document placed on a flat glass plate of No. 0, and information on a sheet size set by the operator via the operation unit 62 are input. When detecting an abnormality in sheet conveyance, the control unit 30 displays a message to the effect that an error has occurred in sheet conveyance on the display 64 to notify the operator.

The copying machine 10 is provided with a counter 32 which operates under the control of the control unit 30.
2 is the second from the detection of the leading edge of the sheet by the first sensor 12
Is used to measure the elapsed time until the sensor 14 detects the leading edge of the sheet.

Further, the copying machine 10 is provided with a storage unit 34 composed of a nonvolatile memory such as an EP-ROM. This storage unit 34 has data 38 relating to a reference count value for each sheet size, which will be described later. Is stored.

Here, with reference to FIGS. 3A to 3D, the principle of sensor signals output in various sheet conveyance states and the detection of skew of the sheet will be described.

As shown in FIG. 3A, when the paper transport state is normal, the first sensor 12 detects the passage of the leading edge of the paper (= the detection signal of the first sensor 12 falls). Then, the time interval T until the second sensor 14 detects the passage of the leading edge of the sheet (= until the detection signal of the second sensor 14 falls) is the time interval T in FIG. The time it takes to do so.

Further, as shown in FIG.
When the upper side (= upper side in FIG. 3B) is inclined forward and in the conveying direction, the first sensor 12 detects the passage of the leading edge of the sheet, and the second sensor 14 detects the leading edge of the sheet. Is shorter than the above-mentioned time interval T.

Further, as shown in FIG.
When the lower side (= lower side in FIG. 3C) is inclined forward in the transport direction and skewed, the first sensor 12 detects the passage of the leading end of the sheet, and then the second sensor 14 The time interval t2 until the passage of the leading edge of the sheet is detected is larger than the time interval T.

Further, as shown in FIG.
If the upper side of the sheet 90 (= the upper side in FIG. 3D) is inclined obliquely forward in the transport direction, the leading end of the sheet 90 may reach the second sensor 14 first.

From the above, the control unit 30 measures the elapsed time from the detection of the leading edge of the sheet by the first sensor 12 to the detection of the leading edge of the sheet by the second sensor 14 by the counter 32, and counts the resulting count. Whether or not the paper 90 is skewed is determined based on whether or not a value n (corresponding to the elapsed time) is equal to a count value corresponding to the time interval T (hereinafter, referred to as a reference count value N). be able to.

That is, if the count value n of the counter 32 is equal to the reference count value N, it is determined that the sheet 90 is not skewed. If the count value n is not equal to the reference count value N, the sheet 90 is skewed. You can judge that you are doing.

Further, the count value n is equal to the reference count value N.
If the count value n is smaller than the reference count value N, it is determined that the upper side of the sheet 90 is inclined forward and in the transport direction as shown in FIG.
As shown in (C), it can be determined that the lower side of the paper 90 is skewed forward in the transport direction. When the leading end of the paper 90 reaches the second sensor 14 first and the time is not counted by the counter 32 (count value n is not obtained),
As shown in FIG. 3D, it can be determined that the upper side of the paper 90 is skewed with a considerable inclination forward in the transport direction.

As described above, in the present embodiment, the control unit 30 always controls the first sensor 1 regardless of the size of the sheet 90 being conveyed.
The counter 32 obtains a count value n corresponding to the elapsed time from the detection of the leading edge of the sheet by the first sensor 12 to the detection of the leading edge of the sheet by the second sensor 14 using the second and second sensors 14. As described above, based on whether the count value n and the reference count value N are equal to each other,
To determine the presence or absence of skew. Therefore, in the data 38 relating to the reference count value for each sheet size in FIG. 4 described above, the reference count value N is set corresponding to all the sheet sizes.

[Operation of the Present Embodiment] Next, as an operation of the present embodiment, a control routine relating to the detection of an abnormality in sheet conveyance performed by the control unit 30 will be described with reference to the flowchart of FIG.

In step 102 of FIG. 5, the storage unit 3 of FIG.
From 4, the reference count value N corresponding to the size of the paper 90 to be conveyed is read. In the next steps 104 and 106, the process waits until the first sensor 12 or the second sensor 14 detects the leading end of the sheet 90.

Here, the first sensor 12 first detects the paper 90
When the leading edge of the sheet 90 is detected, the counter 32 is started in step 108, and in the next step 110, the process waits until the second sensor 14 detects the leading edge of the sheet 90. When the leading edge of the sheet 90 is detected by the second sensor 14, the process proceeds to step 112, where the counter 32 is stopped and the count value n is obtained.

In the next step 114, it is determined whether or not the count value n is equal to the reference count value N. Here, if the count value n is equal to the reference count value N, as described above, it can be determined that the sheet conveyance state is normal as shown in FIG. Therefore, step 11
6 to determine whether or not the execution mode at that time is the automatic paper feed mode. If the execution mode is the automatic paper feed mode, the flow returns to step 104 to execute step 1 for the next paper 90.
04 and subsequent processes are executed. On the other hand, if the mode is not the automatic paper feed mode, the control routine of FIG. 5 ends.

On the other hand, if the count value n is not equal to the reference count value N in step 114, as shown in FIG.
It can be determined that the sheet 90 is skewed as shown in (B) and (C). Therefore, the process proceeds to step 118, where the sheet 90
Is displayed on the display 64 to notify the operator of the occurrence of an abnormality in sheet conveyance. In step 118, the copying process in the copying machine 10 is stopped, and the paper 90 is discharged to the discharge tray 70 in FIG.

When the second sensor 14 first detects the leading end of the sheet 90 in steps 104 and 106, as shown in FIG. You can immediately judge that you are doing. Accordingly, the process proceeds to step 118, where an error message indicating that the sheet 90 is skewed and an abnormality has occurred in the sheet conveyance is displayed on the display 64 to notify the operator of the occurrence of the sheet conveyance abnormality. Further, the copying process in the copying machine 10 is stopped, and the paper 90 is discharged to the discharge tray 70 in FIG.

By executing the control routine as described above, it is possible to accurately detect the occurrence of an abnormality in sheet conveyance using only one counter 32.
Also, the leading edge of the paper 90 is moved to the second position earlier than the first reference position.
In the case where the sheet passes through the reference position, it is possible to quickly detect an abnormality in the sheet conveyance without performing a process such as timing by a counter.

When an abnormality in the sheet conveyance is detected, the copying process is immediately stopped and the sheet 90 is discharged to the discharge tray 70. Therefore, the sheet 90 is conveyed to the copy position in a tilted state, and the sheet 90 is tilted. It is possible to prevent unnecessary copying processing from being performed on the sheet 90. Further, when an abnormality in the sheet conveyance is detected, the error message is immediately displayed on the display 64 to notify the operator of the abnormality in the sheet conveyance, so that the operator can quickly recognize the abnormality in the sheet conveyance, and Can be promptly executed.

By the way, as described above, the count value n
Is smaller or larger than the reference count value N,
The direction in which the sheet 90 is inclined can be determined. That is, if the count value n is smaller than the reference count value N, it is determined that the upper side of the sheet 90 is inclined forward and in the transport direction as shown in FIG.
Is larger than the reference count value N, it can be determined that the lower side of the sheet 90 is inclined forward and skewed as shown in FIG.

Therefore, the control unit 30 may determine the direction in which the sheet 90 is inclined when the sheet 90 is skewed, and may record this in the storage unit 34 as an error record relating to sheet conveyance.

For example, if it is determined in step 114 that the count value n is not equal to the reference count value N as in the control routine of FIG. 6, the process proceeds to step 120, where the count value n and the reference count value N are compared. Judge the size.

Here, the count value n is equal to the reference count value N.
If it is larger, it can be determined that the lower side of the sheet 90 is inclined forward and in the transport direction as shown in FIG. 3C, and the process proceeds to step 122, where the lower side of the sheet 90 is inclined forward in the transport direction. Is determined to be skewed, and the error record of the forward skew error on the lower side of the sheet is updated. For example, the number of occurrences of the forward tilt error on the lower side of the sheet is increased by one.

On the other hand, when the count value n is smaller than the reference count value N in step 120, and in step 104,
When the second sensor 14 first detects the leading end of the paper 90 in 106, the upper side of the paper 90 is skewed forward in the transport direction as shown in FIGS. 3B and 3D. Therefore, the process proceeds to step 124, where it is determined that the upper side of the paper 90 is skewed forward in the conveyance direction, and the error record of the forward tilt error on the upper side of the paper is updated. For example, the number of occurrences of the forward tilt error on the upper side of the sheet is increased by one.

As described above, every time the skew of the sheet 90 is detected, the error record of the sheet conveyance is updated, so that the copying machine 1
0, the information on the paper transport error that has occurred can be stored, and the regular inspector (serviceman) of the copying machine 10 periodically obtains the information on the paper transport error to analyze the tendency of the paper transport error. Can be used.

In the above embodiment, an example was described in which the first sensor 12 and the second sensor 14 were always used irrespective of the size of the conveyed paper. However, as shown in FIG. (Including the direction), the size of the sheet in the direction perpendicular to the transport direction U differs, so the sensor used may be changed according to the size of the sheet.

For example, in the case of B4 vertical size, the sensor 14
In the case of A3 vertical size using the sensor 12S and the sensor 12S, the sensor 14 and the sensor 12T may be used. However, the distance between the two sensors along the transport direction U is the first sensor 1
When the second and second sensors 14 were used, the interval L was used, but when the sensors 14 and the sensors 12S were used,
The interval LS (> interval L) is satisfied, and the sensor 14 and the sensor 1
When 2T is used, the interval LT (> interval LS).

Therefore, in the data 38 relating to the reference count value in FIG. 4, the reference count value corresponding to the interval LS or the interval LT is set in advance as the reference count value corresponding to the size of the sheet 90. For example, the reference count value N corresponding to the A4 vertical size, the reference count value NS corresponding to the B4 vertical size (= the reference count value corresponding to the interval LS), and the reference count value NT corresponding to the A3 vertical size.
(= Reference count value corresponding to interval LT) may be set.

In order to measure the elapsed time from the detection of the leading edge of the sheet by the first sensor 12 to the detection of the leading edge of the sheet by the second sensor 14, a timer may be used instead of a counter.

In the above description, in step 114 of FIG. 5, if the count value n is simply not equal to the reference count value N, it is determined that the sheet is skewed.
When determining whether or not is equal to the reference count value N, a predetermined allowable time error range α is set, and the count value n is equal to or more than (reference count value N−α) and equal to or less than (reference count value N + α). Then, it may be determined that the count value n is equal to the reference count value N.

In addition to displaying an error message on a display, an alarm may be sounded or a combination of these may be used as a means for notifying an operator when a sheet conveyance abnormality is detected. May be.

In the above description, an example is shown in which the paper transport apparatus according to the present invention is applied to a recording paper transport mechanism in a copying machine. Also, the present invention can be applied to a recording paper transport mechanism in a printer, a facsimile, or the like, and the same effect can be obtained.

[0066]

As described above, according to the first aspect of the present invention, the elapsed time from when the leading edge of the sheet passes through the first reference position to when it passes through the second reference position is measured. Since the elapsed time is not equal to the transport reference time and the occurrence of an abnormality in the paper transport is detected by using only one time measuring means, the occurrence of the abnormality in the paper transport is detected with a smaller number of components than in the conventional art. be able to.

According to the second aspect of the present invention, when the leading end of the sheet passes through the second reference position before the first reference position, the abnormality detecting means immediately starts conveying the sheet. Since the occurrence of an abnormality is detected, it is possible to quickly detect the occurrence of an abnormality in sheet conveyance when the sheet is greatly inclined and the leading edge of the sheet passes through the second reference position before the first reference position. it can.

According to the third aspect of the present invention, when it is detected that an abnormality has occurred in the paper conveyance, the conveyance of the paper to a predetermined position is stopped and the paper is discharged to a predetermined discharge tray. Therefore, it is possible to prevent the sheet from being conveyed to a predetermined position in an inclined state, and to perform unnecessary processing (for example, recording an image or reading an image) on the sheet in an inclined state conveyed to a predetermined position. This can be avoided.

According to the fourth aspect of the present invention, when it is detected that an abnormality has occurred in the sheet conveyance, the occurrence of the abnormality is notified to an operator or the like. The occurrence can be promptly recognized, and a countermeasure at the time of abnormality can be promptly executed.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an appearance of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration related to sheet conveyance.

3A and 3B are diagrams showing sensor signals output in various paper transport states, where FIG. 3A shows sensor signals when the paper transport state is normal, and FIG. (C) shows a sensor signal when the paper 12 is inclined forward and in the transport direction, and (C) shows a sensor signal when the leading end of the sheet on the sensor 12 side is inclined forward and in the transport direction. FIG. 3 is a diagram illustrating sensor signals when a leading end of a sheet reaches a sensor 14 first.

FIG. 4 is a block diagram illustrating a configuration of an apparatus for detecting an abnormality in sheet conveyance.

FIG. 5 is a flowchart showing a control routine according to the embodiment of the present invention.

FIG. 6 is a flowchart showing a control routine for performing error recording.

FIG. 7 is a diagram for describing an embodiment in which a plurality of sensors are selectively used according to a paper size.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Copier 12 1st sensor 14 2nd sensor 30 Control part 32 Counter 62 Operation part 64 Display

Claims (4)

[Claims] 1. A sheet conveying device for conveying a sheet of a fixed size to a predetermined position along a predetermined conveying path, wherein the leading end of the sheet passes through a first reference position in the conveying path near the predetermined position. First detecting means for detecting that the sheet has been moved, wherein the leading end of the sheet is separated from the first reference position in a direction perpendicular to the sheet conveyance direction and the predetermined distance from the first reference position. The second in the transport path on the downstream side in the transport direction
A second detecting means for detecting that the sheet has passed the reference position, and a timer for measuring an elapsed time from when the leading end of the sheet passes through the first reference position to when the leading end of the sheet passes through the second reference position. Means, based on the elapsed time and the time required to convey the sheet by the predetermined distance obtained by timing of the timing means, abnormality detection means for detecting that an abnormality has occurred in the conveyance of the sheet; A paper transport device comprising: 2. The method according to claim 1, wherein the abnormality detecting unit is configured to convey the sheet when the leading end of the sheet passes through the second reference position before the first reference position and time counting by the time counting unit is not performed. 2. The sheet conveying device according to claim 1, wherein the occurrence of an abnormality is detected. 3. A control unit for stopping conveyance of the sheet to the predetermined position and discharging the sheet to a predetermined discharge tray when the abnormality detection unit detects that an abnormality has occurred. The sheet transport device according to claim 1. 4. The apparatus according to claim 1, further comprising a notifying unit that notifies the occurrence of the abnormality when the abnormality detecting unit detects that the abnormality has occurred. Paper transport device.