JP2001194834A - Automatic document feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic document feeding device by which the non- feeding and jamming of a document are detected regard-less of the holding state of the document by a roller and also the top and last ends of the document are detected by a simple constitution. SOLUTION: In the document feeding device having a carrying roller 8 to carry paper and a carrying driven roller 8a opposed to the carrying roller 8 and to feed the document, it possesses a document feed rate detecting means 19 coaxially provided with a detecting roller 23 and a rotary encoder 24, and the detecting roller 23 of the document feed rate detecting means 19 is opposed to the carrying roller 8 or the carrying driven roller 8a, and is arranged at a position where it does not come in contact with them and abuts on a passing document.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic document feeder mounted on an image reading apparatus such as a scanner, a copying machine, a facsimile, and the like.

[0002]

2. Description of the Related Art When a long original such as computer foam paper is fed, it is difficult to determine a jam detection standard because the original length is unknown. To detect slippage of long paper, see Japanese Patent Application Laid-Open
Japanese Patent Application Laid-Open No. 155465 discloses a technique for detecting the presence or absence of slippage of a document based on detection signals of a feed amount detecting means and a hole detecting means and controlling conveyance of the document. Absent.

On the other hand, JP-A-9-80828 discloses that
Equipped with a document feed amount detecting means composed of a rotary encoder or the like on the axis of the driven roller, utilizing that the driven roller does not rotate unless a document is conveyed and the output of the document feed amount detecting means is fixed, A technique for detecting a non-feed of a document has been proposed.

[0004]

However, Japanese Patent Laid-Open No. 9-8 / 1994
In the technology described in Japanese Patent Application Laid-Open No. 0828, since the document feed amount detecting means such as a rotary encoder is provided on the driven roller shaft, only non-feeding of the document after the document is sandwiched between the driving roller and the driven roller is detected. There is a problem that can not be.

Conventionally, only a stopped state of a document when the document is sandwiched between a driving roller and a driven roller can be detected, and the leading edge of the document cannot be detected. Therefore, it is necessary to provide a photo sensor or the like as registration detecting means. Yes (for example, JP-A-7-31482), the number of parts is increased, and the cost is increased.

Similarly, since the trailing edge of the original could not be detected, timing detection such as the start of feeding of the next original and the start of the next processing of the main body could not be performed. However, the number of parts increased and the cost increased.

SUMMARY OF THE INVENTION The present invention provides an automatic document feeder capable of detecting non-feeding and jamming of a document and detecting the leading and trailing edges of the document with a simple configuration regardless of the state of the document being held by the rollers. The purpose is to:

[0008]

According to a first aspect of the present invention, there is provided an image forming apparatus comprising: a driving roller for conveying a sheet; and a driven portion opposed to the driving roller, and a document can be fed. A document feeder having a document feed amount detecting means coaxially provided with a detection roller and a shaft rotation amount detection means, wherein the detection roller of the document feed amount detection means faces a driving roller or a driven portion, and It is characterized in that it is arranged in a position where it does not contact with both and abuts on the passing document.

[0009] To achieve the above object, the present invention provides a second aspect.
According to the present invention, in the automatic document feeder according to the first aspect, non-feeding of a document is detected based on the presence or absence of the output of the document feed amount detecting means.

[0010] In order to achieve the above object, a third aspect is provided.
According to the present invention, in the automatic document feeder according to the first aspect, non-feeding of a document is detected by comparing a rotation amount of a driving roller with a rotation amount of a detection roller. .

According to another aspect of the present invention, the above object is achieved.
According to a second aspect of the present invention, in the automatic document feeder according to the second or third aspect, the rotation amount of the drive roller for a distance in which the slip amount is added to the distance from the document set position to the document feed amount detection means; Compare the presence or absence of rotation of the detection roller,
When the detection roller does not rotate, it is determined that paper is not fed.

According to another aspect of the present invention, there is provided a semiconductor device comprising:
According to the present invention, in the automatic document feeder according to claim 1, at least two or more document feed amount detecting means are provided on a feed path for feeding a document, and a document feed amount in a preceding stage with respect to the document feed direction. The invention is characterized in that the output of the detection means and the output of the next document feed amount detection means are compared to detect a document jam in the apparatus.

According to another aspect of the present invention, there is provided a computer system comprising:
According to the present invention, in the automatic document feeder according to the first aspect, the registration position is detected by the output of the document feed amount detecting means.

According to another aspect of the present invention, there is provided a semiconductor device comprising:
According to the present invention, in the automatic document feeder according to the first aspect, the trailing edge of the document is detected by the output of the document feed amount detecting means.

According to another aspect of the present invention, the above object is achieved.
According to a fifth aspect of the present invention, in the automatic document feeder according to the fifth aspect, a function of detecting an abnormality of the document feed amount detecting means by comparing the output of each document feed amount detecting means is provided. It is.

[0016] In the invention according to claims 1 to 4,
Document feed amount detecting means provided with a detection roller and a shaft rotation amount detecting means on the same axis, and the detection roller of the document feed amount detecting means faces the drive roller or the driven portion, and passes without contact with both. It is placed at the position where it touches the original, and compares the amount of rotation of the drive roller for the distance from the original set position to the original feed amount detection means with the amount of slip added, and the presence or absence of rotation of the detection roller at that time. If the detection roller does not rotate, that is, if there is no output from the shaft rotation amount detecting means (rotary encoder), and thus no output from the document feed amount detecting means, it is determined that the paper is not fed.

According to the fifth aspect of the present invention, the leading edge of the document reaches the document feed amount detecting means of the next stage, and the document feed amount per unit time calculated from the output of the document feed amount detecting device of the preceding stage and the document feed amount of the next stage. By comparing the document feed amount per unit time calculated from the output of the document feed amount detection means and calculating the difference in document feed amount between two points, a jam of a long document after passing through the drive roller is detected. Is done.

According to the sixth aspect of the present invention, the output of the shaft rotation amount detection means (rotary encoder) of the document feed amount detection means changes only when the document passes, so that the predetermined stepping motor drive amount at the time of sheet feeding is obtained. By monitoring the output of the rotary encoder of the document feed amount detecting means in the vicinity, it is possible to detect the leading edge of the document (registration detection) at the position of the document feed amount detecting means, and it is necessary to provide a resist detecting means such as a photo sensor. Disappears.

According to the seventh aspect of the present invention, the passage of the trailing end of the document at the position of the document feed amount detecting means can be detected by monitoring the stop state of the output change of the document feed amount detecting means.
It is not necessary to provide a rear end detecting member such as a photo sensor.

According to the present invention, the document feed amount per unit time calculated from the output of each document feed amount detecting means is compared to detect an abnormality in the output of the document feed amount detecting means.
It is possible to prevent a copy image abnormality due to an abnormality of the document feed amount detecting means, a jam of the document, and a situation such as a breakage of the document.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of an automatic document feeder according to an embodiment of the present invention. The automatic document feeder includes a document table 2, a paper feed guide plate 3, a bottom plate 4, a separation mechanism, a paper discharge roller 12, a paper discharge unit 15, and the like.
Hereinafter, the configuration will be described together with the operation.

The originals 1 stacked on the original table 2 with the first image surface facing upward are supplied one by one from the uppermost original in accordance with a signal from a main body (not shown). The leading edge of the document 1 is positioned by abutting the sheet feed guide plate 3. The bottom plate 4 is raised in the direction of arrow A by a solenoid (not shown) in response to a feed start signal from the main body, and presses the original 1 against the calling member 5 from below. The pressurized document 1 is conveyed by a recall member 5 to a separating section including a sheet feeding member 6 and a separating member 7, and is moved from the top to
Separated one by one.

The separated document 1 is transported to a first transport path 21 having a transport roller 8 as a first transport unit and a transport driven roller 8a. When the leading edge of the document is detected by the first document feed amount detecting means 19 as the registration detecting means, the document stops.

The document stopped at the position of the first document feed amount detecting means 19 is conveyed at a speed corresponding to the magnification by a signal from the main body, and the first document feed amount detecting means 19 and the reading unit 10 The time required for the leading edge of the document to pass through the reading unit 10 is calculated from the distance and the transport speed, and when the time has elapsed, the main body is notified that the leading edge of the document has reached the reading unit 10.

When the trailing edge of the conveyed document is detected by the first document feed amount detecting means 19, the next document on the document table 2 is fed, and the first document feed amount detecting means 19 detects the next document. When the leading edge is detected, the document stops (the first document stops on the second transport path 22). Then, the next original is read in the same manner as the first original by a signal from the main body. This operation is performed until there are no more documents on the document table 2.

When the originals on the original table 2 are exhausted, the final original from which the image information has been read is sent to the intermediate conveying roller 11 and the intermediate conveying driven roller 11 as the second conveying means.
a, the paper is discharged to the paper discharge unit 15 through the second conveyance path 22 having the paper discharge roller 12 and the paper discharge lower driven roller 12a. 2
Numeral 0 denotes a second document feed amount detecting means. When the document does not reach the second document feed amount detecting means 20 even after a certain time has elapsed, or when a certain time has passed, the trailing edge of the document does not reach the second document feed amount. If it does not pass through the amount detecting means 20, it is determined that a jam has occurred.

FIG. 2 is a block diagram of the first document feed amount detecting means. The first document feed amount detecting means 19 is configured by coaxially arranging a sponge roller 23 and a rotary encoder 24 serving as a shaft rotation amount detecting means.
Is located near the transport roller 8 and the transport driven roller 8a and near the document 1 when the document 1 passes.

FIG. 3 is a flowchart of the document non-feed detection process. A method of detecting a document non-feed will be described with reference to this flowchart. The roller 23 is rotated by the document when the document 1 passes. Therefore, the output of the rotary encoder 24 alternately repeats the H level and the L level.
The document 1 set on the document table 2 is conveyed to a first conveyance path 21 having a conveyance roller 8 and a conveyance driven roller 8a via a separation unit by driving a stepping motor (not shown) (S1). The driving amount of the stepping motor at this time is accumulated by a CPU (not shown).

Even if the stepping motor is driven by the distance from the document set position to the first document feed amount detecting means 19 in consideration of the slip amount, if there is no change in the output of the rotary encoder 24 (N in S2, Y at S3),
Since the document has not been conveyed to the position where it comes into contact with the roller 23, it is determined that the paper is not fed, and the non-feeding information is notified to a main body (not shown) (S4). In FIG. 3, L1
Indicates the distance from the document setting position to the first document feed amount detecting means 19.

FIG. 4 is a flowchart of the long document jam detection process 1, and FIG. 5 is a flowchart of the long document jam detection process 2. A method for detecting a jam of a long document will be described with reference to these flowcharts.

First, the contents of FIG. 4 will be described. The second document feed amount detecting means 20 is provided with the first document feed amount detecting means 19.
The discharge roller 12 and the lower discharge roller 1
2a, and is located at a position where it comes into contact with the original when the original 1 passes.

The original reaches the second original feed amount detecting means 20 on the second transport path 22 via the first transport path 21.
Here, by counting the number of output pulses of the rotary encoder 24 of the first document feed amount detecting means 19 after the leading end of the document has passed through the first document feed amount detecting means 19,
The feed amount of the document after the leading end of the document has passed through the first document feed amount detecting means 19 can be calculated (Y in S11, S1
2).

The leading edge of the document is the first document feed amount detecting means 1
9, the output of the second original feed amount detecting means 20 does not exceed the distance between the first original feed amount detecting means 19 and the second original feed amount detecting means 20. If there is no change (N in S13, Y in S14), it means that the leading edge of the document has not been conveyed to the position of the second document feed amount detecting means 20, so it is determined that a jam has occurred, and A notification is sent to a main body (not shown) (S15). In FIG. 4, L3 is a signal from the first document feed amount detecting means 19 to the second
The distance to the original feed amount detecting means 20 is shown.

Next, the contents of FIG. 5 will be described. The leading edge of the document reaches the second document feed amount detecting means 20 (Y in S21),
The document feed amount per unit time calculated from the output of the first document feed amount detecting means 19 and the document feed amount per unit time calculated from the output of the second document feed amount detecting means 20 are calculated (S22). , S23), in a state where the trailing edge of the document has not passed through the first document feed amount detecting means 19 (N in S24), the calculated both feed amounts are compared, and if there is a great difference (Y in S25). Since there is a great difference in the document feed amount between the two points, it is determined that a jam has occurred, and the jam information is notified to a main body (not shown) (S26).

If the roller diameter of the first document feed amount detecting means 19 and the roller diameter of the second document feed amount detecting means 20 are the same, the number of pulses per unit time of each document feed amount detecting means, or the number of pulses The jam detection is also possible by comparing the widths.

Next, the detection of the leading edge and the trailing edge of the document by the document feed amount detecting means will be described. The first document feed amount detecting means 19 is arranged near the conveyance roller 8 and the conveyance driven roller 8a in a vicinity and not in contact with the document when the document 1 passes. The output is rotated by the document, and the output of the rotary encoder 24 alternates between an H level and an L level.

Therefore, when paper is fed from the original set position,
A change in the output of the rotary encoder 24 is monitored by a CPU (not shown) in the vicinity of when the stepping motor is driven from the document set position by a distance corresponding to the distance of the first document feed amount detection means 19 and the amount of slip, and , That is, when the leading edge of the document abuts the roller 23 of the first document feed amount detecting means 19 at the document position. The detection of the leading edge of the document at the position of the first document feed amount detecting means 19 is used as registration detection, and the position information of the document is acquired and used for position adjustment at the time of image reading.

On the other hand, when the document passes through the first document feed amount detecting means 19 and the second document feed amount detecting means 20, and the rear end of the document passes through the first document feed amount detecting means 19,
Only the output of the first document feed amount detecting means 19 stops changing. If the stop of the change in the output of the first document feed amount detecting means 19 is monitored by a CPU (not shown),
Of the document at the position of the document feed amount detecting means 19 can be detected. The second document feed amount detecting means 20
In this case, if the time-series change in each document feed amount detecting means is monitored, the trailing edge of the document can be detected.

FIG. 6 is a flowchart for detecting an abnormality of the document feed amount detecting means. The abnormality detection of the document feed amount detecting means will be described based on this flow. The leading edge of the document is second
The document feed amount detecting means 20 (Y in S31), and the first
The document feed amount per unit time calculated from the output of the document feed amount detecting means 19 and the second document feed amount detecting means 20
(S32, S33), and in the state where the trailing edge of the document has not passed through the first document feed amount detecting means 19 (N in S34),
The calculated two feed amounts are compared, and the document feed amount per unit time in the first document feed amount detection unit 19 is smaller than the document feed amount per unit time in the second document feed amount detection unit 20. (Y in S35), which means that the document feed amount is smaller at the position of the first document feed amount detecting means 19 than at the position of the second document feed amount detecting means 20.

Since this phenomenon cannot actually occur, it is considered that the output of the first document feed amount detecting means 19 or the second document feed amount detecting means 20 is not normally obtained.
The main body (not shown) is notified that the document feed amount detecting means is abnormal (S36).

[0041]

According to the first to fourth aspects of the present invention, the original feed amount detecting means having the detecting roller and the shaft rotation amount detecting means on the same axis is provided, and the detecting roller of the original feed amount detecting means is provided. Is disposed at a position opposite to the driving roller or the driven portion, and not in contact with both, and in contact with the passing document;
The rotation amount of the drive roller for a distance in which the slip amount is added to the distance from the document set position to the document feed amount detection means is compared with the presence or absence of rotation of the detection roller at that time, and when the detection roller does not rotate, that is, When there is no output from the shaft rotation amount detecting means (rotary encoder) and, consequently, no output from the document feed amount detecting means, it is determined that the paper is not fed. Therefore, it is possible to detect the non-feed of the document regardless of the state of the document being nipped by the driving roller and the driven portion (the driven roller).

According to the fifth aspect of the present invention, the leading edge of the original reaches the next original feed detecting means, and the original feed per unit time calculated from the output of the previous original feed detecting means and the next original feed. By comparing the document feed amount per unit time calculated from the output of the document feed amount detection means at the second stage and calculating the difference in document feed amount between two points, the jam of a long document after passing through the drive roller is calculated. Can also be detected.

According to the sixth aspect of the present invention, the output of the shaft rotation amount detecting means (rotary encoder) of the document feed amount detecting means changes only when the document passes, so that the predetermined stepping motor at the time of sheet feeding is provided. By monitoring the output of the rotary encoder of the document feed amount detecting means near the drive amount, it becomes possible to detect the leading edge (registration detection) of the document at the position of the document feed amount detecting means, and to detect the resist detection means such as a photo sensor. Since there is no need to provide them, it is possible to reduce the number of parts and cost.

According to the seventh aspect of the invention, by monitoring the stop state of the output change of the document feed amount detecting means, it is possible to detect the passage of the rear end of the document at the position of the document feed amount detecting means, and the photo sensor Since it is not necessary to provide the rear end detection member, the number of parts can be reduced and the cost can be reduced.

According to the eighth aspect of the invention, the document feed amount per unit time calculated from the output of each document feed amount detecting means is compared to detect an abnormality in the output of the document feed amount detecting means, and It is possible to prevent a copy image abnormality due to an abnormality of the amount detecting means, a jam of the original, and a situation such as the damage of the original.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an automatic document feeder according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a first document feed amount detection unit.

FIG. 3 is a flowchart of a document non-feed detection process.

FIG. 4 is a flowchart of a long document jam detection process 1;

FIG. 5 is a flowchart of a long document jam detection process 2;

FIG. 6 is a flowchart of abnormality detection of a document feed amount detection unit.

[Explanation of symbols]

 8 Conveyance roller 8a Conveyance driven roller 19 Document feed amount detection means 23 (Detection) roller 24 Rotary encoder

Claims (8)

[Claims] 1. A document feeder having a drive roller for transporting a sheet and a driven portion opposed to the drive roller and capable of feeding a document, comprising: a detection roller and a shaft rotation amount detection means on the same axis. Document feed amount detection means, and the detection roller of the document feed amount detection means is arranged at a position facing the drive roller or the driven portion, not in contact with both, and in contact with the passing document. Automatic document feeder featured. 2. The automatic document feeder according to claim 1, wherein the non-feeding of the document is detected based on the presence or absence of the output of the document feed amount detecting means. 3. The automatic document feeder according to claim 1, wherein the non-feeding of the document is detected by comparing the rotation amount of the drive roller with the rotation amount of the detection roller. Paper equipment. 4. The automatic document feeder according to claim 2, wherein the amount of rotation of the drive roller is equal to the distance from the original set position to the original feed amount detection means and the amount of slip added. An automatic document feeder, wherein the presence or absence of rotation of a detection roller is compared, and if the detection roller does not rotate, it is determined that paper is not fed. 5. The automatic document feeder according to claim 1, further comprising at least two document feed amount detecting means on a feed path for feeding the document, wherein the document feed amount at a preceding stage with respect to the document feed direction. An automatic document feeder, which detects a document jam in the apparatus by comparing the output of the detection means and the output of the next document feed amount detection means. 6. The automatic document feeder according to claim 1, wherein a registration position is detected based on an output of the document feed amount detecting means. 7. The automatic document feeder according to claim 1, wherein a trailing edge of the document is detected by an output of the document feed amount detecting means. 8. The automatic document feeder according to claim 5, further comprising a function of detecting an abnormality of the document feed amount detecting means by comparing outputs of the document feed amount detecting means. Document feeder.