JPH09226982A - Paper transport device and automatic document feed device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always detect the document length accurately and promptly by judging a paper size from a second timing detecting the tip of a paper and a first timing detecting the rear end of the paper. SOLUTION: Manuscripts taken out from a document feed tray, after copy key ON, and stopped temporarily at a resist roller 17 to have arranged their tips begin to be transported to the document stand direction. When a RGT rear sensor 26 detects the tip of a document, the number of pulses is counted with a pulse detector 34. When a RGT front sensor 24 detects the rear end of the document, the counting operation of pulses with the pulse detector 34 is stopped, and the length of the document is calculated by an ADF processor using the expression of L=S×t+l(mm). Where, L is a length of a document, S is a transport distance where the resist roller 17 transports the document during one pulse, t is the number of pulses entered an AD processor, and l is the distance from the RGT front sensor 24 to the RGT rear sensor 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device for conveying a sheet to a predetermined position and an automatic document feeder for automatically supplying a document to a document table of an image forming apparatus or the like using the sheet conveying device. Regarding

[0002]

2. Description of the Related Art In an automatic document feeder that automatically places a document on a document table of an image forming apparatus and takes out the document from the document table after the image reading is completed, the size of the document supplied from the document tray is As a device for detecting, conventionally, a sensor is provided in front of the registration roller for aligning the leading edge of the document, and a disc-shaped pulse generator is provided on the axis of the registration roller, and a pulse counter starts rotation of the registration roller. The number of pulses generated by the pulse generator is counted until the trailing edge of the document passes the sensor. From the document length = the number of pulses × the document conveyance distance between 1 pulses + the distance between the sensor and the registration roller, The length of the manuscript was calculated.

[0003]

However, in such a conventional apparatus, if the leading edge of the document is not completely caught in the nip portion of the registration roller at the start of rotation of the registration roller, the rotation at the start of rotation will start. The number of pulses corresponding to the time until the leading edge of the document bites into the nip portion is counted extra, and the document length is calculated longer than the actual value from "Equation 2", and the document length is erroneously detected. There was a problem of doing.

Therefore, the present invention eliminates the above-mentioned problems, and always detects the length of the original accurately and quickly even when the leading edge of the original is not completely caught in the nip portion at the start of rotation of the registration rollers. It is an object of the present invention to provide a sheet conveying device and an automatic document feeder that can perform the above.

[0005]

As a first means for solving the above-mentioned problems, the present invention provides a conveying means for conveying a sheet in a predetermined conveying direction, and the sheet conveyed by this conveying means is temporarily stopped. A registration unit that aligns the leading ends and then conveys the sheet in the predetermined conveyance direction; a first detection unit that is provided upstream of the registration unit with respect to the predetermined conveyance direction and detects passage of the sheet; and the registration unit. A second detecting means provided downstream of the predetermined conveying direction for detecting passage of the sheet; a second timing when the leading edge of the sheet is detected by the second detecting means;
Determining means for determining the size of the sheet from the first timing when the trailing edge of the sheet is detected by the detecting means.

The present invention also provides a second object for solving the above problems.
As a means for transporting the sheet, a transporting means for transporting the sheet in a predetermined transporting direction, a registering means for temporarily stopping the sheet transported by the transporting means, aligning the leading ends thereof, and transporting the sheet in the predetermined transporting direction, and the registering means. With respect to the first conveying direction, which is provided upstream of the predetermined conveying direction to detect passage of the sheet, and second detecting means is provided downstream of the registration means with respect to the predetermined conveying direction to detect passage of the sheet. And a determination means for determining the size of the sheet to be conveyed with reference to the distance between the first and second detection means. It is provided.

The present invention also provides a third aspect for solving the above problems.
As means for carrying out the above, a carrying means for carrying the paper in a predetermined carrying direction, a register means for carrying the paper carried by the carrying means to a predetermined position after the paper is temporarily stopped and the leading ends are aligned, and the predetermined means from the register means. First detecting means provided upstream of the sheet conveying direction for detecting the sheet being conveyed by the resisting means, and the sheet being conveyed downstream by the registering means by the registering means, being provided downstream of the registering means. And a control means for starting the size detection of the paper after the leading edge of the paper is detected by the second detection means.

It is something.

The present invention also provides a fourth aspect for solving the above-mentioned problems.
As means for carrying out the above, a carrying means for carrying the paper in a predetermined carrying direction, a register means for carrying the paper carried by the carrying means to a predetermined position after the paper is temporarily stopped and the leading ends are aligned, and the predetermined means from the register means. First detecting means which is provided upstream of the conveying direction of the sheet and detects the trailing edge of the sheet being conveyed by the registering means, and the sheet being conveyed by the registering means which is provided downstream of the registering means in the predetermined conveying direction. Second detecting means for detecting the leading edge, pulse detecting means for detecting the driving of the registration means, and the first edge after the leading edge of the sheet is detected by the second detecting means.
The number of pulses detected by the pulse detection means until the trailing edge of the paper is detected by the detection means of t, the conveyance distance of the paper during one pulse by the conveyance means and the registration means is S, When the distance from the first detecting means to the second detecting means is l, the length L of the sheet is L.
And a control means for calculating by using the formula L = S × t + 1.

A fifth aspect of the present invention is to solve the above problems.
In the automatic document feeder that conveys a document onto a document table and discharges the document from the document table after the reading of the document is completed, a document supporting unit that supports the document and a document placing and supporting unit. Conveying means for conveying the upper original in a predetermined conveying direction, registration means for temporarily stopping the original conveyed by the conveying means, aligning the leading ends thereof, and then conveying the original in the original table direction, and this register means First detecting means provided upstream of the predetermined conveying direction for detecting passage of the original document, and second detecting means provided downstream of the registration means for the passage of the original document to detect passage of the original document. And the second timing when the leading edge of the document is detected by the second detection means and the first timing when the trailing edge of the document is detected by the first detection means. Determination means for determining size, is intended to provide.

The present invention also provides a sixth object for solving the above problems.
In the automatic document feeder that conveys a document onto a document table and discharges the document from the document table after the reading of the document is completed, a document supporting unit that supports the document and a document placing and supporting unit. Conveying means for conveying the upper original in a predetermined conveying direction, registration means for temporarily stopping the original conveyed by the conveying means, aligning the leading ends thereof, and then conveying the original in the original table direction, and this register means First detecting means provided upstream of the predetermined conveying direction for detecting passage of the original document, and second detecting means provided downstream of the registration means for the passage of the original document to detect passage of the original document. And a determination means for determining the size of the document to be conveyed by referring to the detection result of the first and second detection means and the distance between the first and second detection means. That.

The present invention also provides a seventh object for solving the above problems.
In the automatic document feeder that conveys a document onto a document table and discharges the document from the document table after the reading of the document is completed, a document supporting unit that supports the document and a document placing and supporting unit. Conveying means for conveying the upper original in a predetermined conveying direction, resist means for temporarily stopping the original conveyed by the conveying means, aligning the leading ends thereof, and then conveying the original in the original table direction, and the predetermined means by the register means. First detecting means provided upstream of the conveying direction of the document for detecting the original being conveyed by the resisting means, and detecting the original being conveyed by the registering means provided downstream of the registering means in the predetermined conveying direction. And a control means for starting the size detection of the original after the leading edge of the original is detected by the second detecting means.

The present invention also provides an eighth aspect for solving the above problems.
In the automatic document feeder that conveys a document onto a document table and discharges the document from the document table after the reading of the document is completed, a document supporting unit that supports the document and a document placing and supporting unit. Conveying means for conveying the upper original in a predetermined conveying direction, resist means for temporarily stopping the original conveyed by the conveying means, aligning the leading ends thereof, and then conveying the original in the original table direction, and the predetermined means by the register means. First detecting means which is provided upstream of the registration means for detecting the trailing end of the original document being conveyed by the registration means, and the original document which is provided downstream of the registration means in the predetermined conveyance direction and being conveyed by the registration means. Second to detect the tip
Detecting means, pulse detecting means for detecting the driving of the registration means, and the sheet leading edge detected by the second detecting means until the trailing edge of the sheet is detected by the first detecting means. The number of pulses detected by the pulse detection unit is t, the transport distance of the sheet during one pulse by the transport unit and the registration unit is S, and the distance from the first detection unit to the second detection unit. And l is a control means for calculating the length L of the sheet using the formula L = S × t + l.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in FIGS.

FIG. 1 shows an automatic document feeder 12 which is provided so as to face a document table 11 on the upper surface of an image forming apparatus 10 having an image forming means (not shown) and automatically supplies a document to the document table 11. The image forming apparatus 10 is attached so that it can be opened and closed with respect to the document table 11.

The automatic document feeder 12 is a pickup roller 14 which is a take-out unit that takes out a document D on a document feed tray 13 that is a document support unit, a separation / conveyance unit 16, a registration unit, and φ19.97. An endless conveyor belt 20 which is stretched between a registration roller 17 and a belt driving roller 18 each having a diameter, and is slidably contacted with the document table 11.
Belt restraining roller 20 provided on the inner circumference of the conveyor belt 20
a. Further, the automatic document feeder 12 discharges the document D conveyed by the reversing roller 21 and the document reversing roller 21 to the document ejection tray 22 side for transmitting the document D delivered from the document table 11 by the conveyor belt 20. A flapper 25 that switches the conveyance of the paper roller 23 and the document D to either the discharge roller 23 side or the conveyance belt 20 side.
have.

Next, the detection means for detecting the length of the document D placed on the document feed tray 13 will be described in detail. φ1
The registration roller 17 having a diameter of 9.97 is used for the link device 3
6, the gear ratio to the carry motor 31a is 7/24
Are connected. Here, a disc-shaped pulse generator 37 that generates 40 pulses per revolution is attached to the conveyance motor shaft 31b of the conveyance motor 31a. The registration roller 17 is set so that the document D is conveyed by 0.46 mm while the pulse detector 34 that counts the number of pulses from the pulse generator 37 detects one pulse.

Further, upstream of the registration roller 17, a first detection means, which is an RGT front sensor 24 for detecting the rear end of the document D conveyed by the registration roller 17, is provided, and downstream of the registration roller 17. The RGT post-sensor 26, which is the second detection means, detects the leading edge of the document D being conveyed by the registration rollers 17.
The distance between the RGT front sensor 24 and the RGT rear sensor 26 is set to 50 mm.

FIG. 4 is a block diagram showing the control system of the automatic document feeder 12. The ADF processor 27 that controls the automatic document feeder 12 is connected to the main processor 28 that controls the image forming apparatus 10. Controlled. The ADF processor 27 is connected with an RGT pre-sensor 24, an RGT post-sensor 26, and various ADF detectors 30 for detecting the presence / absence of the document D, the feed timing, and the like through the ADF input interface 27a. Furthermore,
The ADF processor 27 has an ADF output interface 2
Pickup roller 14 and registration roller 1 via 7b
The transport driver 31 of the transport motor 31a that drives 7 and the other drivers 32 and 33 that drive the clutch 32a and the solenoid 33a are connected. Further, the ADF processor 27 includes a pulse detector 34 for detecting a pulse generated by the pulse generator 37 attached to the carrier motor 31a.
Is connected.

Next, the operation will be described. At the start of copying, the number of copies, copy magnification, and the like are input from an operation panel (not shown) of the image forming apparatus 10, and the automatic document feeder 1
After the document D is set on the second document feed tray 13, the copy key (not shown) is turned on to start copying. As a result, the image forming apparatus 10 and the automatic document feeder 12 start driving, and in the automatic document feeder 12, the top document D on the document feed tray 13 taken out by the pickup roller 14 is The sheets are separated one by one by the separating / conveying device 16 and sent to the conveying belt 20 via the registration roller 17. Then, while passing through the registration rollers 17, FIG.
The document D size is detected as shown in the flowchart in FIG.

That is, after the copy key (not shown) is turned on, the copy key is taken out from the document feed tray 13 and the registration roller 17 is used.
When the registration roller 17 is driven in step 100, the document D that has been temporarily stopped and the leading edge thereof is aligned is restarted to be conveyed toward the document table 11. When the post-RTG sensor 26 detects the leading edge of the document D in step 101, the process proceeds to step 102, and the pulse detector 34 counts the number of pulses. Next, at step 103, the sensor 2 before RGT
4 detects the rear edge of the document D, the process proceeds to step 104,
Stop counting the number of pulses by the pulse detector 34,
The ADF processor 27 calculates the length of the document D by the following formula.

L = S × t + l [mm] where L is the length of the document D, S is the transport distance for the registration roller 17 to transport the document D during one pulse, and t is the pulse input to the ADF processor 27. The number, 1 is the distance from the RGT pre-sensor 24 to the RGT post-sensor, S = 0.4
Since 6 [mm] and 1 = 50.0 [mm], the length L of the document D is calculated according to the pulse number (t) as L = 0.46 × t + 50 [mm] 106
The document size D is recognized at and input to the main processor (not shown), and the next document size detection is awaited. The original D whose size has been detected in this way and which has reached the conveyor belt 20 is conveyed onto the original table 11 and temporarily stopped at the original reading position.

On the other hand, in the image forming apparatus 10, an image forming means (not shown) performs an image forming step such as a charging step, an exposing step and a developing step on a photoconductor (not shown).
Further, steps such as transfer and fixing of the toner image on the sheet paper are performed to obtain a copy image, but at the time of transfer, the sheet paper conveyed to the transfer position in synchronization with the toner image formed on the photoconductor (see The size (not shown) is selected according to the document size and copy magnification sent from the ADF processor 27 to the main processor 28. During this time, when the reading of the document D placed on the document table 11 is completed due to the end of the exposure process of the final copy, the conveyor belt 20 is re-rotated in the automatic document feeder 12 to copy the document D onto the document table. 11 to the reversing roller 21 side to read the back side, the flapper 25 returns it to the conveyor belt 20 side again, and when the reading is completed, the original sheet discharge tray 22 passes through the sheet discharge roller 23. It will be ejected to the next side, and it will wait for the next document feed.

After this, in the automatic document feeder 12, each time the document D is newly fed, the pulse detector 34
The length of the document D is calculated according to the number of pulses detected by, and the document size is detected. On the other hand, in the image forming apparatus 10, the sheet paper is selected based on the detected document size.

With this configuration, the post-RGT sensor 26
The length of the document D is calculated by using the number of pulses generated by the pulse generator 37 after the leading edge of the document D is detected by the RGT sensor 24 until the trailing edge of the document D is detected by the RGT front sensor 24. The time from the start of driving until the document D actually reaches the post-RGT sensor 26 does not participate in the length detection of the document D. Therefore, even when the leading edge of the document D is not caught in the nip portion of the registration roller 17 at the start of driving the registration roller 17 and it takes time to be caught, the length of the document D is incorrect as in the conventional case. There is no risk of detection of the sheet, and it is possible to prevent a mistake in selecting a sheet in the image forming apparatus 10 and improve reliability. Moreover, the pulse detector 3
Although the timing of starting the counting of the pulse by 4 is later than the conventional one, the timing of the counting end is the time when the trailing edge of the original D passes through the RGT pre-sensor 24 as in the prior art, and therefore the original is swiftly and in the same timing as the conventional. The size of D can be detected, and there is no fear of reducing the processing speed such as the sheet feeding timing in the image forming apparatus 10 thereafter.

The present invention is not limited to the above-described embodiment, and changes can be made without departing from the spirit of the present invention. For example, the conveyance speed of the sheet by the registration means or the first detection means. The distance from the second detecting means to the second detecting means is also arbitrary.

[0027]

As described above, according to the present invention, the leading edge of the sheet temporarily stopped by the registration roller passes through the registration roller and is provided downstream of the registration roller.
Since the detection operation of the paper size is started after the detection is performed by the detection means, the leading edge of the paper is not caught in the nip portion of the registration roller when the registration roller is driven, and it takes time to be caught. Even in the case, there is no risk of erroneously detecting the paper size, and the paper size can be accurately detected regardless of the state of conveyance to the registration rollers.

[Brief description of drawings]

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

FIG. 2 is a schematic explanatory view showing a sheet detection unit according to the embodiment of the present invention.

FIG. 3 is a schematic side view showing a part of the paper detection unit according to the embodiment of the present invention.

FIG. 4 is a schematic block diagram showing a control system of the automatic document feeder according to the embodiment of the present invention.

FIG. 5 is a flowchart showing a document size detecting operation according to the embodiment of the present invention.

[Explanation of symbols]

 10 ... Image forming apparatus 12 ... Automatic document feeder 17 ... Registration roller 24 ... RGT front sensor 26 ... RGT rear sensor 27 ... ADF processor 28 ... Main processor 31a ... Conveyor motor 34 ... Pulse detector 37 ... Pulse generator

Claims (8)

[Claims] 1. A transport means for transporting a sheet in a predetermined transport direction, a registration means for temporarily stopping the sheet transported by the transport means, aligning the leading ends thereof, and then transporting the sheet in the predetermined transport direction, and the resist. First detection means provided upstream of the predetermined conveyance direction with respect to the means for detecting passage of the paper; and first detection means provided downstream of the registration means with respect to the predetermined conveyance direction for detecting passage of the paper. The second detection means, the second timing when the leading edge of the paper is detected by the second detection means, and the first timing when the trailing edge of the paper is detected by the first detection means. A sheet conveying device comprising: a determining unit that determines a size of a sheet. 2. Conveying means for conveying a sheet in a predetermined conveying direction, registration means for temporarily stopping the sheet conveyed by the conveying means, aligning the leading ends thereof, and then conveying the sheet in the predetermined conveying direction, First detection means provided upstream of the predetermined conveyance direction with respect to the means for detecting passage of the paper; and first detection means provided downstream of the registration means with respect to the predetermined conveyance direction for detecting passage of the paper. A second detection unit; a determination unit that determines the size of the sheet conveyed by referring to the detection results of the first and second detection units and the distance between the first and second detection units; A paper transporting device comprising: 3. A conveying means for conveying a sheet in a predetermined conveying direction, a registering means for temporarily stopping the sheet conveyed by the conveying means, aligning the leading ends thereof, and then conveying the sheet to a predetermined position, the registering means comprising: A first detection unit provided upstream of a predetermined sheet conveyance direction to detect the sheet being conveyed by the registration unit; and a first detection unit provided downstream of the registration unit in the predetermined sheet conveyance direction and being conveyed by the registration unit. A sheet conveying device comprising: a second detecting unit that detects a sheet; and a control unit that starts detecting the size of the sheet after the leading edge of the sheet is detected by the second detecting unit. 4. A conveying means for conveying a sheet in a predetermined conveying direction, a registering means for temporarily stopping the sheet conveyed by the conveying means, aligning the leading ends thereof, and then conveying the sheet to a predetermined position. A first detection unit which is provided upstream in a predetermined conveyance direction and detects the trailing edge of the sheet being conveyed by the registration unit; and a first detection unit which is provided downstream of the registration unit in the predetermined conveyance direction and is being conveyed by the registration unit Second detecting means for detecting the leading edge of the sheet; pulse detecting means for detecting the drive of the registration means; after the leading edge of the sheet is detected by the second detecting means; The number of pulses detected by the pulse detection means until the edge is detected is t, and the conveyance distance of the sheet during one pulse by the conveyance means and the registration means is , From said first sensing means second
When the distance to the detection means is 1, the length L of the sheet is
And a control means for calculating by using the formula L = S × t + 1. 5. An automatic document feeder that conveys a document onto a document table and discharges the document from the document table after the reading of the document is completed, a document supporting unit for supporting the document, and a document placing support. Conveying means for conveying the original on the means in a predetermined conveying direction, registration means for temporarily stopping the original conveyed by the conveying means, aligning the leading ends thereof, and then conveying the original in the direction of the original table; And a second detection unit provided upstream of the predetermined conveyance direction for detecting passage of the original document, and a second detection unit provided downstream of the registration unit for detection of the passage of the original document. Means, a second timing when the leading edge of the document is detected by the second detection means, and a first timing when the trailing edge of the document is detected by the first detection means. An automatic document feeder, comprising: a determination unit for determining the size of a draft. 6. An automatic document feeder that conveys a document onto a document table and discharges the document from the document table after the reading of the document is completed, and a document supporting means for supporting the document and a document placing support. Conveying means for conveying the original on the means in a predetermined conveying direction, registration means for temporarily stopping the original conveyed by the conveying means, aligning the leading ends thereof, and then conveying the original in the direction of the original table; And a second detection unit provided upstream of the predetermined conveyance direction for detecting passage of the original document, and a second detection unit provided downstream of the registration unit for detection of the passage of the original document. Means, and a determination means for determining the size of the document conveyed with reference to the detection results of the first and second detection means and the distance between the first and second detection means. Automatic document feeder according to claim. 7. An automatic document feeder that conveys a document onto a document table and discharges the document from the document table after the reading of the document is completed, and a document supporting unit that supports the document and a document placement support. Conveying means for conveying the original document on the means in a predetermined conveying direction; registration means for temporarily stopping the original document conveyed by the conveying means and aligning the leading ends thereof and then conveying the original document in the original table direction; A first detection unit which is provided upstream in a predetermined conveyance direction and detects the original document being conveyed by the registration unit; and a first detection unit which is provided downstream of the registration unit in the predetermined conveyance direction and is being conveyed by the registration unit. A second detection unit for detecting the size of the document, and a control unit for starting size detection of the document after the leading edge of the document is detected by the second detection unit. Automatic document feeder that. 8. An automatic document feeder that conveys a document onto a document table and discharges the document from the document table after the reading of the document is completed, and a document supporting means for supporting the document and a document placing support. Conveying means for conveying the original document on the means in a predetermined conveying direction; registration means for temporarily stopping the original document conveyed by the conveying means and aligning the leading ends thereof and then conveying the original document in the original table direction; A first detection unit provided upstream of a predetermined conveyance direction for detecting the trailing edge of the original document being conveyed by the registration unit; and a first detection unit provided downstream of the registration unit in the predetermined conveyance direction and being conveyed by the registration unit. Second detecting means for detecting the leading edge of the document; pulse detecting means for detecting the driving of the registration means; and, after detecting the leading edge of the sheet by the second detecting means, The number of pulses detected by the pulse detecting means until the trailing edge of the sheet is detected by the first detecting means is t, and the conveying distance of the sheet during one pulse by the conveying means and the registering means is S. , The first detection means to the second
When the distance to the detection means is 1, the length L of the sheet is
An automatic document feeder, comprising: a control unit for calculating the following equation using the formula L = S × t + 1.