JP2001048430A - Sheet transporting device and image forming apparatus having the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply new sheets in the shortest time by calculating the moving time of a side registration detecting sensor from the width of a newly fed sheet to determine the timing of starting to feed a sheet by a sheet supply means, whereby a new sheet is prevented from contacting with a misregistration detecting means. SOLUTION: A sheet P is transported from a lower transport path or a left cassette deck. A photo sensor is used in a side registration detecting sensor 701, and position-controlled vertically to the sheet transport direction by a stepping motor M1 to be on standby in a reference position of a passing sheet size. When the sheet P passes, the sensor detects the sheet end while moving, to measure shifting to the reference position of each sheet size, and according to the shifting amount, the irradiation timing of laser light to the photoreceptor drum is varied to correct the image position to the sheet. The side registration detecting sensor 701 conducts initializing operation for detecting a reference plate 702 provided in the central position of an image to recognize the sensor position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying apparatus having a sheet position deviation detecting function for detecting a deviation of a sheet in a direction perpendicular to the direction in which the sheet is conveyed (the width direction of the sheet). A copying machine that includes a transport device and forms an image by adjusting the position of an image formed on a sheet in accordance with a shift amount of the sheet detected by the sheet transport device;
The present invention relates to an image forming apparatus such as a printer, a facsimile, and a composite device thereof.

[0002]

2. Description of the Related Art Conventionally, there is a sheet position shift detecting device for detecting a shift amount of a sheet in a direction perpendicular to the direction in which the sheet is conveyed (hereinafter, referred to as "sheet width direction").

[0005] The sheet position deviation detecting device is mainly used by being incorporated in an image forming apparatus.

An image forming apparatus in which a sheet position deviation detecting device is incorporated has a sheet position deviation detecting device which detects a deviation amount of a sheet on which an image is formed, and according to the deviation amount, an image formed on the sheet is used by a user. The position of the image is adjusted so that it can be formed at a desired predetermined position.

In particular, the sheet position deviation detecting device is incorporated in a digital copying machine (image forming apparatus) having an automatic double-sided device, and is used for correcting a lateral registration deviation of an image on the second side during double-sided copying. Often.

A digital copying machine having an automatic duplexer is
A sheet on which an image has been formed on the first side (for example, the front side) is turned over by a reversing roller or the like without forming an image on the intermediate tray, and an image is formed on the second side (for example, the back side). It is a stackless type digital copier.

[0007] To detect the amount of lateral registration deviation, a movable lateral registration detection sensor (position deviation detection means) for detecting the lateral registration position is made to stand by at a reference position where the end of each sheet size passes, and is moved to the reference position. There is known a method of measuring a shift amount with respect to the distance.

[0008]

However, the image forming apparatus comprises: a sheet reversing conveyance path for re-feeding a sheet from an inverted sheet reversing path to an image forming section (image forming means) for forming an image on the sheet; It is configured to share a sheet conveyance path for feeding sheets from a cassette storage in which sheets are stacked to the image forming unit. The lateral registration detecting sensor of the sheet position deviation detecting device is installed in the shared conveyance path.

For this reason, when the width of the re-fed sheet is different from the width of the sheet fed from the cassette storage unit, the sheet misalignment detecting device detects the width of the re-fed sheet by a waiting lateral registration detecting sensor. There has been a problem that the edge of the sheet hits and a detection error occurs or the lateral registration detection sensor is damaged.

According to the present invention, for example, when a new sheet is fed from the cassette storage to the same sheet conveying path by the sheet feeding means after the sheet is re-fed from the sheet reversing conveying path, the sheet is fed. By calculating the movement time of the lateral registration detection sensor from the width of the new sheet, and determining the timing of starting feeding by the sheet feeding means, the new sheet does not hit the displacement detection means,
It is another object of the present invention to provide a sheet misalignment detecting device capable of supplying the new sheet in the shortest time and an image forming apparatus provided with the device.

[0011]

According to another aspect of the present invention, there is provided a sheet conveying apparatus including: a first sheet conveying path having an upstream side connected to a first sheet supplying means for supplying a first sheet; A second sheet feeding path having an upstream side connected to a second sheet feeding means for feeding a second sheet and having a downstream end joined to the one sheet feeding path; and wherein the second sheet feeding path is the first sheet feeding path. A third sheet conveying path branched off from the one sheet conveying path and joined to the second sheet conveying path at a downstream side of a first merging point joining the path;
The third sheet transport path is disposed downstream of a second junction where the third sheet transport path merges with the second sheet transport path, moves in a direction crossing the second sheet transport path, and moves from the third sheet transport path to the second sheet transport path. The first sheet that is fed into the two-sheet conveying path and moves
A displacement detection unit for detecting a displacement in the width direction of the sheet; and a current position of the displacement detection unit so that the second sheet supplied from the second sheet supply unit does not interfere with the displacement detection unit. Supply control means for controlling the timing of the supply of the second sheet by the second sheet supply means based on the control information.

The standby position of the displacement detecting means of the sheet conveying apparatus according to the present invention is an end portion of the sheet parallel to the sheet conveying direction.

[0013] The image forming apparatus of the present invention may include any one of the above.
One sheet conveying device and the first of the sheet conveying devices.
The first sheet conveying path, which is disposed on the first sheet conveying path between a junction and a branch point where the third sheet conveying path branches from the first sheet conveying path and is conveyed along the first sheet conveying path. Image forming means for forming an image on one sheet and the second sheet, and sheet discharging provided on the first sheet conveying path downstream of the branch point to discharge the first sheet and the second sheet Means, and the third sheet conveying path is a sheet reversing conveying path for reversing and conveying the first sheet and turning over the first sheet.

In the image forming apparatus according to the present invention, the supply control means of the sheet conveying apparatus may be configured so that the position shift detecting means detects a sheet conveyed from the sheet reversing conveying path to the second sheet conveying path. Controlling the supply timing of the second sheet by the second sheet supply unit in accordance with the time required to move from the standby position to the standby position when detecting the second sheet supplied by the second sheet supply unit. It has become.

In the image forming apparatus according to the present invention, an image forming position by the image forming means is corrected in accordance with a sheet position shift amount detected by the sheet position shift detecting device.

(Operation) When the first sheet is conveyed on the second sheet conveying path, the position shift detecting means of the sheet conveying apparatus of the present invention moves in the direction traversing the second sheet conveying path, and moves to the first position. The position of the sheet is detected, and how much the first sheet deviates from the reference position is detected.

Thereafter, if the width of the second sheet supplied from the second sheet supply means is wider than the width of the first sheet for which the positional deviation has been previously detected, the second sheet supplied from the second sheet supply means is provided. The sheet may interfere with the displacement detecting means.

Therefore, the supply control means, when the displacement detecting means, which is considered to be a position not interfering with the second sheet supplied by the second sheet supply means, has retreated, the second sheet fed by the second sheet supply means. The sheet feeding timing by the second sheet supply means is controlled so that the sheet reaches the displacement detection means.

When the first sheet is conveyed from the sheet reversing conveyance path to the second sheet conveyance path, the position shift detection means of the image forming apparatus of the present invention moves in a direction crossing the second sheet conveyance path, The position of the first sheet is detected, and how much the first sheet is shifted from the reference position is detected.

Thereafter, if the width of the sheet supplied by the second sheet supply means is wider than the width of the first sheet which has been conveyed through the sheet reversing conveyance path and whose width has been detected, the second sheet supply means is provided. There is a possibility that the second sheet supplied from the printer may interfere with the displacement detecting means.

Therefore, when the displacement detecting means retracts to a position where the second sheet supplying means does not seem to interfere with the second sheet supplied from the second sheet supplying means, the second sheet feeding means feeds the second sheet. The timing at which the second sheet is fed by the second sheet supply means is controlled so that the sheet reaches the position shift detection means.

The image forming apparatus according to the present invention corrects the image forming position by the image forming means in accordance with the amount of sheet displacement detected by the sheet conveying device, and forms an image at a predetermined position on the sheet.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a digital copying machine which is an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a digital copying machine.

The reader section 1 reads an image of a document and outputs image data corresponding to the document image to the image memory section 3.

The printer section 2 records an image corresponding to the image data from the image memory section 3 on a sheet.

The image memory unit 3 compresses and stores the image data transferred from the reader unit 1, and expands the stored compressed image data and transfers it to the printer unit 2. Further, the image memory unit 3 transfers the stored image data to the external I / F processing unit 4 and
The image data transferred from the F processing unit 4 is stored.

The external I / F processing section 4 performs predetermined processing on the image data transferred from the image memory section 3, outputs the processed image data to an external device, and performs predetermined processing on the image data sent from the external device. And transfers it to the image memory unit 3.

The automatic document feeder 6 is connected to the reader unit 1 and feeds a document placed on the automatic document feeder 6 to a predetermined position.

FIG. 2 is a schematic front sectional view of the digital copying machine.

Reference numeral 200 denotes the main body of the digital copying machine 199. Reference numeral 6 denotes an automatic document feeder. Reference numeral 201 denotes a platen glass as a document table.

The scanner 202 has an original illumination lamp 203.
And a scanning mirror 204 and the like. Scanner 20
2 is reciprocated in a predetermined direction by a motor, so that the reflected light of the document passes through the lens 207 via the scanning mirrors 204 to 206 and forms an image on the CCD sensor in the image sensor unit 208.

An exposure control unit 209 composed of a laser, a polygon scanner, or the like is converted into an electric signal by the image sensor unit 208, and is modulated based on an image signal on which predetermined image processing described later has been performed. Is irradiated on the photosensitive drum 211.

Around the photosensitive drum 211, an image forming unit 2 such as a primary charger 212, a developing unit 213, a transfer charger 216, a pre-exposure lamp 214, a cleaning device 215, etc.
10 are equipped.

The photosensitive drum 211 is rotated by a motor (not shown) in the direction of the arrow shown in FIG.
After being charged to a desired potential by the exposure control unit 12
9 is irradiated with the laser light 219 to form an electrostatic latent image. The electrostatic latent image formed on the photosensitive drum 211 is
The image is developed by the developing device 213 and visualized as a toner image.

On the other hand, pick-up rollers 225, 226, 2 from right cassette deck 221, left cassette deck 222, upper cassette 223 or lower cassette 224.
The sheet P supplied by the sheets 27, 228 is sent to the main body by sheet feeding rollers 229, 230, 231, 232 provided in sheet supply paths 271, 272, 273, 274.
And the visualized toner image is transferred to the transfer charger 216.
Is transferred to a sheet.

The sheet supply paths 273 and 274 merge at the downstream side to form a common sheet supply path. The downstream side of the merged sheet supply paths 273 and 274 is further downstream of the sheet supply path 271. And the sheet feeding path 241 merges into a common sheet supply path 275, which extends to the transfer belt 234 via the image forming unit 210.

After the transfer, the photosensitive drum 211 is cleaned of residual toner by the cleaner device 215, and residual charge is erased by the pre-exposure lamp 214.

The sheet after the transfer is separated from the photosensitive drum 211 by the separation charger 217 and the transfer belt 23
4 to the fixing device 235. In the fixing device 235, the toner is fixed by pressure and heat, and is discharged to the outside of the main body 200 by the discharge roller 236.

On the right side of the main body 200, for example, about 4000
A deck 250 capable of storing a number of sheets is provided. The lifter 251 of the deck 250 rises according to the amount of the sheet so that the sheet always contacts the pickup roller 252, and the sheet is fed into the main body by the sheet feeding roller 253 provided in the sheet supply path 277. Further, on the right side of the main body 200, a multi-bypass tray 254 capable of storing about 100 sheets is provided. The sheet on the multi-bypass tray 254 is supplied to the sheet feed roller 2 provided in the sheet supply path 276 which joins the sheet supply path 275.
It is sent to the image forming unit 210 by 46.

The paper discharge flapper 237 switches the path between the transport path 238 and the discharge path 243. The lower conveyance path 240 is configured to turn a sheet sent out from the sheet discharge roller 236 through a reversing path 239 and turn the sheet over and guide the sheet to a re-feeding path 241.

From the left cassette deck 222 to the paper feed roller 2
30 is also supplied to the sheet supply path 272.
From the paper feed path 241.
The re-feed roller 242 is configured to re-supply the sheet to the image forming unit 210.

Immediately after the re-feed roller 242, a lateral registration detection sensor 701 is disposed. Lateral registration detection sensor 7
Reference numeral 01, as will be described later, detects a shift amount in the vertical direction (shift amount in the width direction of the sheet) with respect to the conveying direction of the sheet guided from the lower conveying path 240. A discharge roller 244 serving as a sheet discharge unit is provided with a discharge flapper 237.
And a roller for discharging the sheet switched to the discharge path 243 side by the discharge flapper 237 to the outside of the apparatus.

During double-sided recording (double-sided copying), the discharge flapper 237 is raised upward, and the copied sheet is guided to the re-feeding path 241 via the transport path 238, the reversing path 239, and the lower transport path 240. . At this time, the sheet
The reversing roller 245 causes the rear end of the sheet to completely escape from the conveyance path 238, and is pulled into the reversing path 239 to a position where the sheet is bitten by the reversing roller 245, and is sent out to the conveyance path 240 by the reversal of the reversing roller 245.

When the sheet is reversed and discharged from the main body 200, the discharge flapper 237 is raised upward, and the sheet is temporarily reversed by the reversing roller 245 to a position where the rear end remains in the transport path 238. And is sent out to the transport path 240 by the reverse rotation of the reversing roller 245, so that it is turned over and sent out to the discharge roller 244 side.

The sheet discharge processing device 290 stacks and aligns sheets discharged one by one from the main body 200 of the digital copying machine on the processing tray 294, and when one sheet is discharged,
The sheet bundle is stapled and discharged to the discharge trays 292 and 293.

The paper discharge trays 292 and 293 are controlled to move up and down by a motor (not shown), move to the position of the processing tray 294 which is the start position before the image forming operation starts, and thereafter, the discharged sheets are stacked. And the height of the sheet surface is moved to the position of the processing tray 294. Further, the discharge trays 292 and 293 can store a maximum of about 2000 sheets, and when one of the trays reaches the maximum amount, the height of the sheet surface is processed so as to be stacked on the other tray. It is moved to the position of the tray 294.

The paper tray 291 is a tray for stacking separator sheets to be inserted between the discharged sheets. The Z-folding machine 295 is configured to Z-fold the discharged sheet. In addition, the bookbinding machine 296 performs a bookbinding operation by folding the ejected sheets into a part and folding the sheets in the center, closing them with staples, and performing bookbinding. The bound sheet bundle is discharged to a discharge tray 297.

FIG. 3 is a control block diagram of the digital copying machine 199.

The CPU 171 performs basic control of the digital copying machine 199. The ROM 174 stores a control program, and the work RAM 17 performs processing.
5 and the input / output port 173 are connected by an address bus and a data bus.

The CPU 171, the ROM 174, the work RAM 175, and a later-described lateral registration detection unit 176 constitute a supply control unit.

The input / output port 173 is connected to various loads (not shown) such as a motor and a clutch for controlling the digital copying machine 199, and inputs (not shown) such as sensors for detecting the position of the sheet. .

The CPU 171 performs input / output control sequentially through the input / output port 173 according to the contents of the ROM 174 to execute an image forming operation. An operation unit 172 is connected to the CPU 171 and controls a display unit and a key input unit of the operation unit 172. The operator switches the display of the image forming operation mode, the scanner reading mode, and the print output mode through the CPU 17 through key input means.
1 and the CPU 171 displays the state of the digital copying machine 199 and the operation mode setting by key input.

The CPU 171 is connected to a lateral registration detecting unit 701 for notifying the CPU 171 of the detected lateral registration deviation amount.
01 (see FIGS. 2 and 12), and also manages the travel time to the next position. Further, the CPU 171 includes:
An image processing unit 170 that processes a signal converted into an electric signal by the image sensor unit 208 and an image memory unit 3 that stores a processed image are connected.

Next, based on FIG.
Will be described.

FIG. 4 is a block diagram of the image processing unit.

The original image formed on the CCD sensor 208 via the lens 207 (see FIG. 1) is input as Black luminance data, and is converted into an analog electric signal by the CCD sensor.

The converted image information is input to an analog signal processing unit (not shown), and after performing sample & hold, dark level correction, etc., an A / D conversion unit 501 performs analog / digital conversion (A / D conversion). / D conversion) and shading correction of the digitized signal (correction of variations in a sensor for reading a document and light distribution characteristics of a document illumination lamp). After that, it is sent to the log converter 502.

The log converter 502 stores an LUT for converting the input luminance data into density data, and converts the luminance data into density data by outputting a table value corresponding to the input data. .

Thereafter, the image is scaled to a desired magnification by the scaling unit 503 and input to the γ correction unit 504. γ
When outputting the density data, the correction unit 504 performs conversion using an LUT in consideration of the characteristics of the printer, and adjusts the output according to the density value set by the operation unit.

After that, it is sent to the binarizing section 505. The binarization unit 505 binarizes the multi-value density data, and the density value becomes “0” or “255”. 8 bits (bi
The image data of t) is binarized and converted into 1-bit image data of “0” or “1”, and the amount of image data stored in the memory is reduced.

However, when an image is binarized, the number of tones of the image is changed from 256 to two. Therefore, when image data having a large number of halftones such as a photographic image is binarized, image deterioration generally occurs. Remarkable.

Therefore, it is necessary to perform pseudo halftone expression using binary data. Here, an error diffusion method is used as a method for pseudo-halftone expression using binary data.
According to this method, when the density of a certain image is larger than a certain threshold value, it is determined that the density data is “255”, and when the density is less than a certain threshold value, the density data is “0”. Is a method of distributing the difference between the density data and the binarized data to surrounding pixels as an error signal.

The distribution of the error is performed by multiplying the weighting coefficient on the matrix prepared in advance by the error generated by the binarization and adding the result to the surrounding pixels. As a result, the density average value of the entire image is stored, and the halftone can be represented in a pseudo binary manner. 2
The digitized image data is sent to the image memory unit 3 and is stored in the image. The image data from the computer input from the external I / F processing unit 4 is processed as binary image data by the external I / F processing unit, and thus sent to the image memory unit 3 as it is.

The image memory section 3 has a high-speed page memory and a large-capacity memory (hard disk) capable of storing a plurality of page image data. The plurality of image data stored in the hard disk are output in an order according to the editing mode specified by the operation unit of the digital copying machine 199. For example, in the case of sorting, the images of the document bundle read from the automatic document feeder 6 are sequentially output. The image data of the document once stored is read from the hard disk, and this is repeated a plurality of times and output. Thereby, it can play the same role as a sorter having a plurality of bins.

The image data output from the image memory unit 3 is sent to a smoothing unit 506 in the printer unit 2.
The smoothing unit 506 performs data interpolation so that the line ends of the binarized image are smoothed, and the exposure control unit 2
09 to output image data. The exposure control unit 209 forms image data on a sheet by the above-described processing.

Next, the image memory unit 3 will be described with reference to FIG.

The image memory unit 3 stores a binary image from the external I / F processing unit 4 and the image processing unit 170 via a memory controller unit 302 in a page memory unit 301 composed of a memory such as a DRAM. It performs writing, reading an image to the external I / F processing unit 4 and the printer unit 2, and accessing the hard disk 304 as a large-capacity storage device for inputting and outputting an image.

The memory controller 302 generates a DRAM refresh signal for the page memory 301, and arbitrates access to the page memory 301 from the external I / F processor 4, image processor 170, and hard disk 304. I do.

Further, the memory controller 302
In accordance with an instruction from the PU 171, the write address to the page memory unit 301, the read address from the page memory unit 301, and the read direction are controlled.

Accordingly, the CPU 171 controls the function of laying out a plurality of original images in the page memory unit 301 and outputting them to the printer unit, the function of cutting out and outputting only a part of the image, and the image rotation function.

Next, the configuration of the external I / F processing unit 4 will be described with reference to FIG.

The external I / F processing section 4 fetches the binary image data of the reader section into the external I / F processing section 4 via the image memory section 3 as described above, and Then, the binary image data from the external I / F processing unit is output to the printer unit 2 to form an image.

The external I / F processing section 4 includes a core section 406, a facsimile section 401, a hard disk 402 for storing communication image data of the facsimile section, and an external computer 1
1, a computer interface unit 403 connected to
It has a formatter unit 404 and an image memory unit 405.

The facsimile unit 401 is connected to a public line via a modem (not shown), and receives facsimile communication data from the public line and transmits facsimile communication data to the public line. Facsimile unit 401
The facsimile function, such as sending a fax at a designated time or sending image data in response to a query from a partner for a designated password, the hard disk 40
Then, a fax image is stored in the printer 2 and processing is performed. Thus, the facsimile unit 401 and the facsimile hard disk 4 are once transmitted from the reader unit 1 via the image memory unit 3.
After the image is transferred to F.02, fax transmission can be performed without using the reader unit 1 and the image memory unit 3 for the facsimile function.

Computer interface unit 403
Is an interface unit for performing data communication with an external computer, and has a local area network (hereinafter, LAN), a serial I / F, an SCS II / F, a centro I / F for inputting data to a printer, and the like. . The computer interface unit 403
The status of the printer unit and the reader unit are notified to the external computer via / F, and the image read by the reader unit 1 is transferred to the external computer according to the instruction of the computer. Further, the computer interface unit 403
Receive print image data from an external computer.

Since the print data notified from the external computer via the computer interface unit 403 is described in a dedicated printer code, the formatter unit 404 forms the image in the printer unit 2 via the image memory unit 3. To raster image data.

The formatter unit 404 develops raster image data in the image memory unit 405.

As described above, the image memory unit is used as a memory in which the formatter unit 404 expands raster image data, and sends an image of the reader unit to an external computer via the computer interface unit 403 (image scanner function). In this case, it is also used when the image data sent from the image memory unit 3 is expanded once in the image memory unit, converted into a format of data to be sent to an external computer, and then sent out from the computer interface unit 403.

The core unit 406 includes a facsimile unit 401,
It controls and manages data transfer among the computer interface unit 403, the formatter unit 404, the image memory unit 405, and the image memory unit 3. Accordingly, even if the external I / F processing unit 4 has a plurality of image output units or the image memory unit 3 has only one image transfer path, the core unit 40
Under the management of No. 6, exclusive control and priority control are performed, and image output is performed.

Next, the operation of the automatic document feeder 6 according to the present invention will be described with reference to FIG.
The description will be made based on FIG.

First, each part of the automatic document feeder 6 will be described with reference to FIG.

The paper feed roller 601 drops on the original surface of the original bundle 621 placed on the original tray 620 on which the original bundle 621 made up of at least one sheet is placed, and rotates by rotating the original bundle. Is supplied to the original document D on the uppermost surface.

The stopper 611 projects as shown in FIG. 7A before the start of document feeding, and the document bundle 621 is restricted by the stopper 611 so that it cannot advance downstream.

The original fed by the paper feed roller 601 is separated into one sheet by the action of the separation roller 602 and the separation belt 603. Separation is achieved by the well-known retard separation technique. The transport roller 604 transports the document separated by the separation roller 602 and the separation belt 603 to the registration roller 605, and the registration roller 605
The skew in the conveyance of the document is eliminated by abutting the document against the document and forming a loop.

Below the registration roller 605, the document passing through the registration roller 605 is fed along the paper feed path 652 or the reverse entrance path 6, which is a conveyance path in the direction of the platen 201.
A reversing paper feed flapper 613 for guiding to 53 is provided. First reversing roller 614 and second reversing roller 615
Rotate when the document is reversed. The reversing flapper 612 guides a document arriving from the direction of the second reversing roller 615 to the reversing path 650 or the re-feeding path 651.

The belt driving roller 606 drives a feeding belt 607 for arranging a document on a platen. The feeding belt 607 is in contact with the platen 201. The paper feed / discharge roller 617 feeds / discharges the document supplied from the manual paper feed port 622 and discharges the document D fed by the feed belt 607 to the document discharge port 623. Paper ejection flapper 6
16 is a manual feed / discharge path 654 or a document discharge path 6;
The document is guided to 55. The paper discharge flapper 616 acts to prevent the document from being discharged toward the manual paper discharge port 622 when the document is discharged. The manual feed / discharge roller 619 feeds / discharges a manual document. The discharge roller 618 discharges the document.

Further, three sensors 608, 609, and 610 are arranged below the document tray 620. The document set detection sensor 610 is a transmissive optical sensor that detects that the document bundle 621 has been set. The document trailing edge detection sensor 608 is a reflection type optical sensor for determining whether the document is a half size document. A final document detection sensor 609 between the document set detection sensor 610 and the document trailing edge detection sensor 608 is a reflection type optical sensor for determining whether the document being transported is the final document.

The original size detecting sensors 624 and 62
Reference numerals 5 and 626 denote sensors for detecting the size of the original being conveyed. Three sensors are arranged in the width direction of the original.
The document width is detected in three stages based on the sensor values of
The system, or the document width of A4 and A5 can be determined. Also, the length of the original can be detected based on the passage time of the original. This makes it possible to detect individual document sizes even in a document bundle in which documents of different sizes are mixed. However, at this time, the bundle of originals is placed with the back side in the width direction of the originals aligned.

Next, the operation of the automatic document feeder 6 when reading both sides of a document printed on both sides (double-sided document) will be described.

When the automatic document feeder 6 is instructed to start feeding a double-sided document, the stopper 611 is lowered, and the paper feed roller 601 is further dropped on the upper surface of the document (FIG. 7B).

By the action of the paper feed roller 601, the separation roller 602, the separation belt 603, and the conveyance roller 604, only one document is separated from the uppermost surface of the document bundle 621 and fed to the registration roller 605 (FIG. c)). At this time, the reversing paper feed flapper 613 is set in the direction of transporting the original to the reversing path 650.

When the registration roller 605 rotates, the original is conveyed to the position shown in FIG. 8E via the path shown in FIG. 7D. From here, the driving directions of the first reversing roller 614 and the second reversing roller 615 are reversed, the document is fed onto the platen 201, and stops at the position shown in FIG.

When the reading of the original is completed, FIG.
As shown in FIG. 8, the original is turned over via a re-feed path 651, and as shown in FIG.
01.

When the reading of the original document is completed, the original document D is fed rightward and discharged from the original discharge port 623 to the outside of the apparatus.

By repeating the above operation, the automatic document feeder 6 separates the two-sided document one by one from the uppermost surface, reads both sides, and discharges the document with the upper surface facing down (face down). it can.

Next, the scanner 202 is fixed at a predetermined position, and the operation of the original reading method (flow reading) for reading an image by moving the original is described in the case where the original is only the small size and the case where the large size is included. Will be described separately.

In the present embodiment, the small size is a size at which the document trailing edge detection sensor 608 does not detect a document when the document bundle 621 is placed on the document tray 620, and the large size is a size at the document tray 620. Document bundle 62
This is the size at which the document trailing edge detection sensor 608 detects the document when the document No. 1 is placed.

First, the flow reading of a small-size original will be described.

The operation until the document reaches the registration roller 605 is as described with reference to FIGS. 7A to 7C.

In the case of the flow reading, as shown in FIG. 9 (i), the reversal sheet feeding flapper 613 transfers the original to the platen 20.
Lead up one. The document is conveyed at a predetermined speed above point A in the figure, and the image of the document is
02 (FIG. 9 (j)). Point A is defined as the position where the trailing edge of the small size document has passed the registration roller 605. The document D is conveyed to the right in the drawing and discharged from the document discharge port 623 to the outside of the automatic document feeder 6 (FIG. 9 (k)).

Next, the flow reading of a document including a large size will be described. The operation until the document reaches the registration rollers 605 is as described with reference to FIGS. 7A to 7C. In the case of the flow reading, as shown in FIG.
Lead up one. The document is conveyed at a predetermined speed above point B in the figure, and the image of the document is read by the scanner 202 waiting below point B. Point B is defined as the position where the trailing edge of the large-sized document has passed the registration roller 605. The document D is conveyed to the right in the figure as it is, and is discharged from the document discharge port 623 to the outside of the automatic document feeder 6 (FIG. 10 (m)).

Finally, in the case of original fixed reading in which an image is read by moving the scanner 202, the original is placed at a position where the rear end of the original is aligned with the end of the platen 201 (the position shown in FIG. 8H).

Next, the direction of the document bundle 621 set on the document tray 620 of the automatic document feeder 6 (see FIG. 7) and the document bundle 6 conveyed and discharged to the document discharge port 622
FIG. 11 shows how the directions of 21 correspond. FIG.
The document shown on the left side of 1 is a document bundle 621 set on the document tray 620. Since the document with the number 1 on the top surface of this document is conveyed in order and output with its front and back reversed, the top document is reversed and its bottom surface is turned down as shown on the right side of FIG. Is discharged.

Next, the operation of the horizontal registration detecting unit 176 will be described with reference to FIG.
A description will be given based on the cross-sectional view of FIG.

FIG. 12 is a view of a section perpendicular to the sheet conveying direction as viewed from the left side of the main body.

The sheet P is conveyed from the lower conveyance path 240 or the left cassette deck 222, and proceeds in the depth direction in the drawing (the direction in the back of the drawing). A photo sensor is used as the lateral registration detection sensor 701, and its position is controlled by a stepping motor M1 in the direction perpendicular to the sheet conveyance direction (the left-right direction in the drawing, the width direction of the sheet). stand by. When the sheet P passes, the edge of the sheet is detected while moving, and the deviation of each sheet size from the reference position is measured. By changing the irradiation timing of the laser beam 219 to the photosensitive drum 211 according to the measured shift amount, the image position on the sheet is corrected.

The lateral registration detection sensor 701 performs an initialization operation for detecting the reference plate 702 provided at the center of the image, and recognizes the sensor position.

In the image forming apparatus having the above-described configuration, the left cassette deck 222 is operated after the double-sided mode is performed.
A control example in the case where the mode of feeding a sheet from is performed will be described.

FIG. 13 is a diagram showing a state in which the sheet is fed from the left cassette deck 222 and the lateral displacement is detected until the first sheet is fed, and the left cassette deck 222 is moved.
Is a flowchart showing the control method, and is started when an instruction to supply the first sheet is issued.

First, in step (abbreviated as “S” in FIG. 13) 1, it is determined whether the previous mode is the duplex mode. If the mode is not the double-sided mode, the lateral registration detection sensor 701 may be moved directly,
To determine whether the width of the sheet on the left cassette deck 222 (hereinafter abbreviated as “C2” and abbreviated as “C2” in FIG. 13) is wider than the width of the currently stopped sheet. .

If the width is wider, the process proceeds to step 3, where the lateral registration detection sensor 701 is started to move to the sheet width of C2, and the moving time is calculated. Subsequently, the process proceeds to step 4, wherein C2
It is determined whether the time required for the sheet fed from the printer to reach the lateral registration detection sensor 701 is shorter than the movement time calculated in step 3.

If the arrival time is short, the process proceeds to step 5, and it is determined whether or not the time of (movement time-arrival time) has elapsed. If not, return to step 5 and wait until the time has elapsed. If the time has elapsed in step 5, the process proceeds to step 6, and sheet supply is started.

In step 4, if the arrival time is not short, the movement of the lateral registration detecting sensor 701 is completed before the sheet reaches the lateral registration detecting sensor even if the supply of the sheet is started immediately. Therefore, the process proceeds to step 6 to start sheet supply.

In step 2, if the sheet width of C2 is smaller than the width at which the sheet is currently stopped, the process proceeds to step 6 immediately after the sheet is conveyed without hitting the lateral registration detection sensor 701. The sheet supply is started.

In step 1, if the previous mode is the duplex mode, the lateral registration detecting operation of the previous sheet may still be performed.
01 cannot be moved.

Therefore, the process first proceeds to step 7, where it is determined whether the width of the sheet C2 is wider than the width of the preceding sheet. If it is wider, the process proceeds to step 8, and the time for moving the lateral registration detection sensor to the sheet width of C2 is calculated. Then, the process proceeds to a step 9, wherein it is determined whether or not a time for making a gap with the previous sheet is shorter than the movement time calculated in the step 8. If the inter-sheet time is short, the process proceeds to step 10, where it is determined whether or not the rear end of the previous sheet has passed the lateral registration detection sensor. If it has not passed, it returns to step 10 and waits for it to pass.

If the sheet has passed in step 10, the flow advances to step 11 to start moving the lateral registration detection sensor to the sheet width of C2. Subsequently, the process proceeds to step 12, where it is determined whether (moving time−arrival time) has elapsed. If not, the process returns to step 12, and waits until the time has elapsed.

If the time has elapsed in step 12, the flow advances to step 6 to start sheet supply. This allows
Immediately after the movement of the lateral registration detection sensor, the sheet fed from C2 can pass through the lateral registration detection sensor. In step 9, if the time for making a gap with the previous sheet is not shorter than the movement time calculated in step 8, the process proceeds to step 13. In step 7, C
If the width of the second sheet is smaller than the width of the previous sheet, the process proceeds to step S13.

In step 13, it is determined whether or not the rear end of the previous sheet has passed the lateral registration detection sensor. If it has not passed, it returns to step 13 and waits for it to pass.

If the sheet has passed in step 13, the process proceeds to step 14, in which sheet supply is started so that a specified sheet is opened between the sheet fed from C2 and the previous sheet.

By controlling as described above, when a mode for feeding sheets from the left cassette deck 222 is instructed, during the double-sided mode operation, the passage time of the previous sheet and the moving time of the lateral registration detection sensor are reduced. If the operation is not in the double-sided mode, the sheet feeding from the left cassette deck 222 can be started without waste after waiting for the movement time of the lateral registration detection sensor. The sheet can be fed without hitting the sheet.

Next, the correspondence between the embodiment and the claims will be described.

In FIG. 2, a lateral registration detecting sensor is disposed downstream of a junction A1 between the sheet supply path 272 and the lower transport path 240.

In this case, the right cassette deck 22
1. Upper cassette deck 223, Lower cassette deck 2
24, the deck 250, or the multi-bypass tray 254 corresponds to the first sheet.
5, 227, 228, 252 and paper feed rollers 246,
A roller facing any one of the sheets corresponds to a first sheet supply unit, and the cassette decks 221, 223,
250, a path from the multi-purpose tray 254 to the transfer belt 234 via the image forming unit 210, and the transfer belt 234.
And the discharge path 243 correspond to the first sheet conveying path, the sheet in the left cassette deck 222 corresponds to the second sheet, the pickup roller 226 corresponds to the second sheet supply unit, and the sheet supply path 272 is The sheet feeding path 241 corresponds to the second sheet conveying path, and the re-feeding path 241 is joined to the common sheet supply path 279 downstream of the sheet supply paths 271, 273, and 274 at the first junction. Correspondingly, the conveying path 238, the reversing path 239, and the lower conveying path 240 branched at the branch point B from the sheet conveying path 278
Corresponds to the sheet transport path (sheet reverse transport path), and
Junction point A of lower conveyance path 240 and sheet supply path 272
2 corresponds to the second junction.

Note that the lateral registration detecting sensor 701 may be provided between the junction A1 and the junction A3 of the sheet supply paths 279 and 277.

In this case, the junction A3 becomes the first junction, and the junction A1 becomes the second junction. And Deck 2
50, any one of the multi-bypass tray 254 corresponds to the first sheet, and among the pickup roller 252 and the paper feeding roller 246, the roller facing any one of the sheets corresponds to the first sheet supply means, and the cassette Deck 25
0, the path from the multi-bypass 254 to the transfer belt 234 via the image forming unit 210, the transfer belt 234, and the discharge path correspond to the first sheet conveying path, and the right cassette deck 222, the upper cassette deck 223, and the lower cassette One of the sheets of the deck 224 corresponds to the second sheet,
The pickup rollers 225, 227, 228 correspond to the second sheet supply means, and the sheet supply paths 271, 273,
274 corresponds to the second sheet conveying path.

Note that the lateral registration detection sensor 701 may be provided between the junction A3 and the junction A4 of the sheet supply paths 275 and 276.

In this case, the junction A4 becomes the first junction, and the junction A3 becomes the second junction. The sheet of the multi-bypass 254 corresponds to the first sheet, the roller facing the paper feed roller 246 corresponds to the first sheet supply unit, and the path from the multi-bypass 254 to the transfer belt 234 via the image forming unit 210 is determined. , The transfer belt 234 and the discharge path 243 correspond to the first sheet conveying path,
Fifty sheets correspond to the second sheet, the pickup roller 252 corresponds to the second sheet supply unit, and the sheet supply path 279 corresponds to the second sheet conveyance path.

[0130]

According to the present invention, when the width of the second sheet supplied by the sheet supply means is wider than the width of the sheet for which the position of the first sheet has been previously detected, the position shift detection means is provided. The sheet feeding by the second sheet feeding means is started in accordance with the retreat movement of the second sheet, so that the interference between the displacement detecting means and the second sheet can be prevented, and both can be prevented from being damaged.

In addition, since the displacement detecting means does not interfere with the second sheet, the displacement detection accuracy can be improved.

Further, it is possible to narrow the interval of conveying the sheets having different widths, and it is possible to enhance the detection efficiency.

In the image forming apparatus according to the present invention, after the first sheet is re-fed from the sheet reversing conveyance path to the second sheet conveyance path, the second sheet is supplied by the second sheet supply means via the same second sheet conveyance path. When feeding the sheet, the second
Calculate the travel time of the displacement detection means from the width of the sheet,
By determining the timing for starting the feeding, it is possible to prevent the second sheet from interfering with the position shift detecting means, so that the second sheet can be supplied in the shortest time.

Further, it is possible to prevent interference between the displacement detecting means and the second sheet, thereby preventing both of them from being damaged.

Further, since the misalignment detecting means and the second sheet do not interfere with each other, the accuracy of misregistration detection is improved, and the position of the image with respect to the sheet is accurately adjusted to form the image accurately at a predetermined position. Can be.

Further, it is possible to reduce the conveying interval of sheets having different widths, and it is possible to enhance the image forming efficiency.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a digital copying machine that is an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic front sectional view of the digital copying machine of the present invention.

FIG. 3 is a control block diagram of the digital copying machine of the present invention.

FIG. 4 is a block diagram of an image processing unit of the digital copying machine according to the present invention.

FIG. 5 is a configuration diagram of an image memory unit of the digital copying machine of the present invention.

FIG. 6 is a configuration diagram of an external I / F processing unit of the digital copying machine of the present invention.

FIG. 7 is a schematic front sectional view for explaining the operation of the automatic document feeder. FIG. 3A is a diagram illustrating an operation of feeding a sheet to a platen. FIG. 4B is a diagram illustrating an operation of feeding a sheet to a platen. FIG. 3C is a diagram illustrating an operation of feeding a sheet to a platen. FIG. 6D is a diagram illustrating an operation of feeding a sheet to a platen.

FIG. 8 is a schematic front sectional view for explaining the operation of the automatic document feeder. (E) is a diagram illustrating an operation of feeding a sheet to a platen. FIG. 5F is a diagram illustrating a state in which a document is being read. (G) is a diagram showing a state in which the original is turned upside down. (H) is a diagram illustrating a state in which the other side of the document is read and the document is discharged.

FIG. 9 is a schematic front sectional view for explaining the operation of the automatic document feeder. FIG. 5I is a diagram illustrating a state in which small-sized originals are scanned and read. (J) is a diagram illustrating a state in which a small-sized document is being scanned and read. (K) is a diagram illustrating a state in which a small-sized document is being discharged.

FIG. 10 is a schematic front sectional view for explaining the operation of the automatic document feeder. (L) is a diagram illustrating a state in which a large-size document is scanned and started to be read. (M) is a diagram illustrating a state in which a large-size document is ejected while being scanned.

FIG. 11 is a diagram illustrating the direction of a document bundle discharged from a document discharge port.

FIG. 12 is a cross-sectional view in the width direction of a refeeding path provided with a lateral registration detection sensor.

FIG. 13 is a control flowchart of the present invention.

[Explanation of symbols]

P sheet A1, A2, A3, A4 Confluence point B Junction point 177 CPU (supply control means) 174 ROM (supply control means) 175 RAM (supply control means) 176 Horizontal registration detection section (supply control means) 199 Digital copier ( Image forming apparatus 200 Body of digital copying machine 210 Image forming unit (image forming means) 701 Horizontal registration detection sensor (position shift detecting means) 221 Right cassette deck 222 Left cassette deck 223 Upper cassette deck 224 Lower cassette deck 225, 227, 228, 252 Pickup roller 226 Pickup roller 238 Transport path 239 Reverse path 240 Lower transport path 241 Refeed path 243 Discharge path 244 Discharge roller (discharge means) 246 Feed roller 250 deck 254 Multi manual tray 271, 273, 274,279,275,276
Sheet supply path 272 Sheet supply path

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Mitsuhiko Sato, Inventor 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Hideyuki Ikegami 3-30-2, Shimomaruko, Ota-ku, Tokyo Canon Incorporated F term (reference) 3F053 EA01 EB01 EB04 EC04 EC14 ED02 ED12 ED25 ED31 LA01 LB02 3F100 AA04 BA13 CA10 CA12 DA04 DA08 EA06

Claims (5)

[Claims] A first sheet feeding path having an upstream side connected to a first sheet feeding means for feeding a first sheet; and a second sheet feeding means for feeding a second sheet having a width different from that of the first sheet. The upstream side is connected, and
A second sheet conveyance path having a downstream end joined to the sheet conveyance path; and a branch from the one sheet conveyance path downstream of a first junction where the second sheet conveyance path merges with the first sheet conveyance path. A third sheet conveying path joined to the second sheet conveying path, and a second sheet conveying path arranged downstream of a second junction where the third sheet conveying path joins the second sheet conveying path. The first sheet moving in a direction traversing the sheet conveying path and being sent from the third sheet conveying path to the second sheet conveying path and moving;
A position shift detecting unit configured to detect a position shift of the sheet, and the second sheet supplied from the second sheet supply unit is configured to be based on a current position of the position shift detecting unit so as not to interfere with the position shift detecting unit. And a supply control means for controlling the timing of the supply of the second sheet by the second sheet supply means. 2. The sheet conveying apparatus according to claim 1, wherein the standby position of the position shift detecting unit is an end portion of the sheet parallel to the sheet conveying direction. 3. The sheet conveying apparatus according to claim 1, wherein the first converging point of the sheet conveying apparatus and a branch point where the third sheet conveying path branches from the first sheet conveying path. An image forming unit that is arranged in the first sheet conveyance path between the first sheet and the second sheet that is conveyed through the first sheet conveyance path and forms an image on the first sheet and the second sheet; Sheet discharging means provided in the first sheet conveying path for discharging the first sheet and the second sheet, wherein the third sheet conveying path reversely conveys the first sheet and turns over the sheet. An image forming apparatus characterized in that the image forming apparatus is a sheet reversing conveyance path. 4. The sheet feeding device according to claim 1, wherein the position control unit detects the position shift detecting unit from the standby position when detecting the sheet conveyed from the sheet reversing conveyance path to the second sheet conveyance path. A timing of supplying the second sheet by the second sheet supply unit is controlled in accordance with a time for moving to the standby position when the second sheet supplied by the two sheet supply unit is detected. The image forming apparatus according to claim 3. 5. The image forming apparatus according to claim 4, wherein an image forming position by said image forming means is corrected in accordance with a sheet position shift amount detected by said sheet position shift detecting device.