JP2003262990A - Both-surface recording position correction - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust a deviation in the relative positional relation between an image on the top surface (1st surface) and an image on the reverse surface (2nd surface). <P>SOLUTION: An image forming part forms a prepared 1st adjustment image (image shown by 'top' of Fig. 10) on a sheet and then forms a 2nd adjustment image (image shown by 'reverse' of Fig. 10) on the same surface where the 1st adjustment image is formed in response to the feeding of the surface of the sheet where the 1st adjustment image is formed (refeeding using a flapper 31 or a multiple-manual-insertion paper feed part 1 in Fig. 1) to the image forming part. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus having functions such as a copying machine, a laser beam printer, and a facsimile, an image forming apparatus used as an output device such as a multifunction machine and a workstation having those functions,
And a method of controlling the image forming apparatus.

[0002]

2. Description of the Related Art As a conventional double-sided image forming apparatus capable of forming images on both sides of a sheet, a first image formed on a latent image carrier such as a photoconductor is transferred to the surface (first side) of the sheet. After fixing, the sheet is reversed and re-fed, and then the second image formed on the latent image carrier is transferred and fixed on the back surface (second surface) of the sheet.

However, generally, in this method, when the sheet is reversed and re-fed, the sheet is conveyed in the front direction (first
Since the front side and the back side are treated as the image reference, the image reference position on the sheet is substantially different between the front side and the back side, and the front and back images are There is a risk of misalignment.

Therefore, as an example of measures for reducing the image position deviation, when an image is transferred to the front surface (first surface),
By setting the front end side in the sheet conveyance direction as the image reference position, and for the sheet that has been turned upside down through the sheet reversing path, the image transfer reference position is provided at the rear end side in the sheet conveyance direction when transferring the back side image. Since the image transfer position reference for the front and back sides of the sheet can be the same, there is a method for reducing the positional deviation of the images on the front and back sides.

[0005]

However, the above-mentioned double-sided image forming apparatus has the following problems. Even when a double-sided image is formed on both sides of one sheet with one end of the sheet as an image reference, the relative positional relationship between the front side (first side) image and the back side (second side) image is misaligned. It may happen. This is caused by variations in geometric shape accuracy such as the size of the sheet, parallelism between sheet end faces, variations in conveyance accuracy, and expansion and contraction of the sheet due to the effect of heat pressure when the sheet passes through the fixing device. I often do it.

If the deviation of these double-sided images becomes large enough to be visually recognized, it becomes a factor of degrading the image quality. Therefore, the amount is often grasped and corrected by the following method. The front side (first side) image and the back side (second side) image were watermarked, and the paper surface was folded and the front and back images were compared to check the amount of misalignment. Since the amount of deviation is determined, it is difficult to estimate the accurate amount of deviation depending on how the boundaries are not clear and how the paper is folded and how the images are aligned. In addition, in thick paper, it is not possible to estimate the amount of misalignment itself because the front and back images cannot be compared for transmission. Further, since the deviation between the front and back cannot be measured on the same surface of the sheet, it is difficult to perform simple automatic measurement, and it is difficult to inexpensively perform automatic adjustment in the machine.

The present invention has been made to solve the above-mentioned problems, and a second side image, which is originally a back side image, is formed on a sheet surface on which the first side is image-formed as a front side image, and both images are formed. By comparing the positions, the relative positional deviation between the front and back images between the two surfaces can be grasped easily and clearly using a single surface on the sheet. This provides an image forming apparatus capable of obtaining an image relationship without image shift between the front and back sides based on this amount.

[0008]

That is, the first aspect of the present invention relates to a sheet to be fed (each sheet feeding means 1, 1 ', 1''in FIG. 1) as shown in FIG. In an image forming apparatus having an image forming unit (electrophotographic recording unit 101 in FIG. 1) that forms an image on a stored sheet, it is instructed to adjust the image forming position (operation unit 219 in FIG. 1). Accordingly, the first adjustment image (the image shown in “Table” in FIG. 10, the reference image (Table) in FIG. 14) prepared in advance by the image forming unit is formed on the sheet, and the first image is further formed on the sheet. When the surface on which the adjustment image is formed is fed to the image forming unit (re-feeding using the flapper 31 in FIG. 1 or the multi-purpose manual feeding unit 1 ″), the first adjustment image is displayed. The second adjustment image (the image shown in the "back" of FIG. 10, FIG. 14) is formed on the same surface as the formed surface. Characterized in that it has a control means for controlling to form a reference image (back)).

According to a second aspect of the present invention, in the image forming apparatus, an adjusting means for adjusting an image forming position (the main body control unit 200 in FIG. 2 is the exposure unit 15 and the registration roller 7 in FIG. 1).
Etc.) and image forming position display setting means (operation panel 219 in FIG. 1) for displaying a setting screen for setting the adjustment amount by the adjusting means.

A third invention according to the present invention is characterized in that the image forming position display setting means has a display control means for controlling to display information regarding a processing procedure in a transition in a unit of one screen.

According to a fourth aspect of the present invention, the control means forms at least one set of the first and second adjustment images (a plurality of adjustment images in a direction orthogonal to the sheet conveying direction shown in FIG. 10). (Positional deviation confirmation marks) corresponding to 1 to 5).

A fifth aspect of the present invention is characterized in that the first adjusted image is a scale image (FIG. 14) having a pitch different from that of the second adjusted image.

A sixth invention according to the present invention is characterized in that a vernier scale image is constituted by a combination of the first and second adjustment images.

According to a seventh aspect of the present invention, in the image forming apparatus, the measuring means for measuring the positional deviation amount in the scanning direction based on the first and second images formed on the same surface (see FIG. 1).
The front and back image shift detecting means 32) and the adjusting means for adjusting the image forming position based on the measurement result of the measuring means.

According to an eighth aspect of the present invention, in the image forming apparatus, when an image is normally formed on both sides, the image forming reference position on the front surface is at the leading end in the sheet conveying direction and the image forming reference position on the back surface is. Is the rear end side in the sheet conveying direction, and the image forming reference position is always the front end side in the conveying direction in response to the instruction of the image forming position.

In a ninth aspect of the present invention, the image forming apparatus forms the first adjusted image on the sheet in order to form the second adjusted image in response to an instruction to adjust the image forming position. And a re-conveying unit that feeds the surface on which the adjusted image is formed to the image forming unit.

In a tenth aspect of the present invention, the image forming apparatus forms the first adjusted image on the sheet in order to form the second adjusted image in response to an instruction to adjust the image forming position. And a detachable re-conveying unit that feeds the surface on which the adjusted image is formed to the image forming unit.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view for explaining the structure of an image forming apparatus showing one embodiment of the present invention. In FIG.
10Y, 10M, 10C, and 10K are yellow,
Image forming portions for magenta, cyan, and black, and 8 is an intermediate transfer belt. In each image forming unit, a charging device 14, an exposure device 15, a developing device 16, a transfer device 17, and a cleaner 18 are arranged around the photosensitive drum 13, and a toner image of each color is formed on the surface of the photosensitive drum 13 by an electrophotographic process. Form.

A toner image corresponding to each color is formed on each of the photosensitive drums 13C, 13M, 13Y, and 13K by an image information signal sent from the document reading device 12 or an output device (not shown) such as a computer, and the toner image is formed. Toners of respective colors are sequentially transferred onto the intermediate transfer belt 8 made of a flexible sheet material to form a color image on the intermediate transfer belt 8.

Surface (first surface) using electrophotographic process
To form the image on the sheet, send the sheet to the toner image formed on the intermediate transfer belt so that the toner image is transferred to a desired position with the leading edge of the sheet in the conveyance direction as a reference. The toner image is transferred in synchronization with. The sheets stored in the cassette 1, 1'or the multi-manual sheet feeding unit 1 '' are fed by the feeding rollers 2, 2'or 2 '' and then conveyed by the conveying rollers 3 to 6 before the registration. It reaches the registration roller 7 through the sensor 7 ′. After detecting the leading edge of the sheet by the pre-registration sensor 7 ′, the skew is corrected by the registration rollers 7 for a predetermined time, and then the toner image is transferred to a desired position with the leading edge in the sheet conveying direction as a reference. The toner image formed on the intermediate transfer belt is fed toward the intermediate transfer belt 8 in synchronization with the sheet feeding.
The sheet sent out from the registration roller 7 merges with the intermediate transfer belt 8 in the secondary transfer portion 9, and the four color toners are collectively transferred from the intermediate transfer belt 8 to the sheet. Four
The sheet on which the batch transfer of the color toner images has been completed is conveyed by the conveying unit 9 ′.
To reach the fixing roller pair 19. Fusing roller pair 19
Are heated by a heater (not shown), and the toner of each color is melted by heat and fixed on the sheet to complete a color image. The sheet on the surface of which the toner image has been fixed by the fixing roller pair 19 is discharged as it is to the outside of the apparatus.

When an image is to be formed on the back side, the sheet is guided and conveyed to the reversing section 20 by the first sheet conveying direction changing device (flapper) 30, and the sheet conveying direction is reversed from the front end to the rear end, that is, a so-called switch. Back operation to prepare for new image transfer. Then, a new image is additionally formed on the back surface through the same image forming process as the front surface image formation, and then the image is discharged to the outside of the apparatus. Further, by installing the second sheet conveyance direction conversion device (flapper) 31 before the sheet conveyance path after the toner image of the first surface is fixed and entering the reversal path 20, the image of the first surface can be obtained without performing the switchback operation. A conveyance path is formed on the sheet surface on which the second surface image, which would otherwise be the back surface image, can be formed.

Even if the image forming apparatus does not have the first sheet conveying direction changing device (flapper) 30 or the second sheet conveying direction changing device (flapper) 31, an image is formed on the front surface (first surface). The sheet discharged to the outside of the apparatus is re-fed to the image forming unit by using the multi-purpose manual paper feeding unit 1 ″, so that the back face (second face) or the same face (first face)
It is also possible to form an image on the surface).

FIG. 2 is a block diagram showing the configuration of the control circuit in the image forming apparatus of FIG. In FIG. 2, 2
Reference numeral 00 denotes a main body control unit of the image forming apparatus for controlling the driving of the image reading unit, the image forming unit 205, and the like.
An RO including a PU, a RAM providing a work area of the CPU, and a program for executing each operation mode described later, and storing a control program for the entire image forming apparatus.
With M and.

For example, the main body control unit 200 controls switching of the flappers 30 and 31 to form a double-sided image to switch the sheet conveying direction, and the original document feeding device control unit 216 feeds the original document. Device control of the image forming apparatus and image data control for instructing the post-processing apparatus control unit 217 what mode to set.

The image processing unit 202 performs image processing corresponding to the image processing function set by the operation unit 219 on the image data output from the CCD 201. Two
Reference numeral 03 denotes a laser unit 204, an image data compression / decompression unit 207, an image memory 208, a function control unit 209, and an image data bus, which will be described later. , An image data selector for selecting a direction in which image data flows.

Reference numeral 204 is a laser unit for performing laser exposure on the image data developed on the sheet in the image forming section 205. The image forming unit 205 actually develops the laser-exposed image data on a sheet as described above.

Reference numeral 206 denotes an inter-CPU communication I / F (interface) for communicating control information between the main body control unit 200 and a function control unit 209 described later. Reference numeral 207 denotes a compression of the image data output from the image data selector 203, in order to save the image data occupation ratio on the HD when the image data is accumulated in the hard disk (HD) which is a large-capacity nonvolatile memory. And again H
Image data compression / expansion to the original image data when transferring the compressed image data on D to the image data selector
It is an extension part. An image memory 208 is a volatile memory for temporarily storing the image data sent from the image data selector 203 and transferring the temporarily stored image data to the image data selector 203.

The function control section 209 converts the image data sent from the network communication I / F 215 into the image data selector 203 and sends the image data sent from the print image conversion section 214 to the image data selector 203. , Inter-CPU communication I for communicating image forming apparatus control information from the operation unit 219 of the main body between CPUs
It communicates with the main body control part 200 via / F210. C
The inter-PU communication I / F 210 communicates the control information of the image data stored in the HD 212 between the HD control unit 211 and the main body control unit 200. The HD control unit 211 writes the image data sent from the image data compression / expansion unit 207 to the HD 212, reads the image data stored in the HD 212, and sends the image data to the image data compression / expansion unit 207. Based on the control information from the main body control unit 200 sent through the inter-CPU communication I / F 210. The HD 212 is the HD control unit 21.
This is a non-volatile memory in which the image data sent from the image data compression / expansion unit 207 or the image data sent to the image data compression / expansion unit 207 is written and read under the control of 1.

Reference numeral 214 denotes a network communication I / which will be described later.
A print image conversion unit that converts image data described in PDL transferred from application software operating on a host computer connected to a network in F215 into image data that can be printed out by the image forming unit 205 of the image forming apparatus. Is. Two
Reference numeral 15 denotes a communication I / F for connecting to the image forming apparatus via a network. That is, communication of image data and control information is performed with a device (computer or the like) on the network based on a specific communication protocol (protocol).

Reference numeral 216 is a document feeding device control unit for controlling the document feeding device 101 for feeding a plurality of documents, which will be described in detail with reference to FIG. 3, to the document table, and based on control information from the main body control unit 200. Feed the manuscript. A post-processing apparatus control unit 217 performs post-processing of an output sheet, and performs post-processing of a sheet on which image formation has been completed (hereinafter referred to as output paper) based on control information from the main body control unit 200. . The document reading unit 218 irradiates the document based on the control information from the device control unit 200 and drives the optical unit to project the reflected light of the document image on the CCD 201. Two
Reference numeral 19 is an operation unit of the image forming apparatus according to the embodiment of the present invention.

FIG. 3 is a diagram showing the operation unit 219 in FIG. 2 in detail. In FIG. 3, reference numeral 301 denotes a ten-key pad used when inputting the number of copies and the amount of image movement. A start key 302 is used to start a copy job. Reference numeral 303 denotes a stop key, which can be pressed to stop the job when the started job is to be stopped midway. 304 is LC
The D display / input unit is generally used for setting the mode of a copy job and displaying the operating state of the copying machine. The LCD display / input unit 304 is composed of a touch panel display. Reference numeral 305 denotes a user mode key for setting each item of the user mode for performing operations and display settings reflected in the standard mode for the copying machine. In the present embodiment, the LCD display / input unit 304 is used as an adjustment setting unit to display the procedure / information for adjusting the image forming position and input the adjustment amount on the touch panel. A power saving mode key 306 is used by the user to shift to a power saving mode in which the copying machine main body saves power in a standby state after a job such as copying is completed.

In the above configuration, a screen transition will be described with respect to the series of operations.

4 to 9 are diagrams showing screen transitions during setting and processing of image recording position adjustment in double-sided image formation. FIG. 4 is a diagram showing a standard screen displayed on the LCD 304. Pressing each icon on the standard screen 310 opens a sub-window for various settings. 315
Includes a copy function to copy originals, a send function to send original image data to devices on the network, a box function to store original image data, and a print function to form images of image data from devices on the network. This is a key group that allows selection of functions for each job such as extended functions. Reference numeral 312 denotes a paper feed stage selection icon. When pressed, a sub-window for selecting the paper feed stage opens, and the paper feed stage can be displayed and selected. A key group 314 determines an image mode, and various image modes can be selected, and the density can be changed by the density key according to the mode.
A key group 313 for changing the magnification of the document includes various keys. A sorter key 316 is used to set finishing after the recording paper is output. 317
Is a double-sided key, and sets various modes such as reading one side of a document, reading both sides, outputting on one side of recording paper, or outputting on both sides.

FIG. 5 is a sub-window displayed when the double-sided key 317 of FIG. 4 is pressed, and in this type of selection window 320, items to be selected or set are listed. Select when you want to make two-sided copies of two single-sided originals on the front and back of one sheet. Single-sided / double-sided mode key 321. Select when you want to automatically reverse both-sided originals and make two-sided copies on the front and back of one sheet. 2-sided / 1-sided mode key 322, a 2-sided / 1-sided mode key 323 to be selected when automatically inverting a 2-sided original to make a 1-sided copy of the front and back sides of the original on different sheets, right or left of a spread original such as a book, or Page continuous shooting double-sided mode key 324 selected when copying front and back pages on the front and back of one sheet of paper, detailed setting key 325 for making detailed settings for each mode, adjustment of image forming position when images are formed on both sides The adjustment mode key 326 for performing the
When is pressed, the settings are registered and the standard screen shown in FIG. 4 is displayed.

FIG. 6 is a sub-window displayed when the adjustment mode key 326 of FIG. 5 is pressed. The adjustment mode start window 330 starts the recording position adjustment mode for the front and back images during double-sided image formation. When the adjustment mode start key 331 is pressed to display a confirmation message to do so and the adjustment is started, the screen is shifted to the screen of FIG. 7 and the adjustment mode is started. When the adjustment mode is not desired to be started, the stop key 332 is pressed to shift to the type selection window 320 without starting the adjustment mode.

FIG. 7 shows the adjustment mode start key 331 of FIG.
This is a sub-window that is displayed when is pressed. This adjustment mode selection window 340 includes a manual feed adjustment mode key 341 and a cassette to be selected when the adjustment mode is performed using only the multi-manual paper feed unit 1 ″. Manual cassette adjustment mode key 342 to be selected when performing the adjustment mode by using the multi-manual sheet feeding unit 1 ″ for sheet re-feeding from the sheet feeding unit 1 and the second sheet conveyance direction conversion device ( This is an automatic adjustment mode key 343 to be selected in the case where the same face is automatically re-fed by the structure having the flapper 31 and is used as a sheet feeding stage when the device is configured or both sides are performed. Also select various modes. It should be noted that these mode keys may be hidden if they cannot be used depending on the configuration of the apparatus, and it is possible to avoid the complexity of user settings.

(Manual Feed Adjustment Mode) The manual feed adjustment mode which is performed by using only the multi manual feed section 1 '' will be described. This mode does not have a conveyance path for both sides, that is, the first sheet conveyance direction changing device (flapper) 30.
Also, even when a double-sided image is formed by an image forming apparatus that does not have the second sheet conveying direction changing device (flapper) 31, the adjustment is performed using only the multi-manual sheet feeding unit 1 ″. Further, this mode is used for adjustment when the multi-manual paper feeding section performs both sides even if it has a two-sided conveyance path, at the user's request.

FIG. 8A is a window displayed when the manual feed adjustment mode key 341 of FIG. 7 is pressed,
This is a window for displaying a message for setting a sheet in the multi-manual sheet feeding section 1 ″ and pressing the start key 302. If you press the start key here, the LCD 304
A window shown in FIG. 8B is displayed on the screen, so that the operator can easily understand the situation. At that time, the image forming apparatus feeds the sheet, forms the adjusted image of the first surface on the sheet by using the electrophotographic process, and discharges the sheet on which the toner image is fixed on the surface by the fixing device as it is to the outside of the apparatus. , LCD304
Switches to the window in FIG.

FIG. 8C shows the sheet discharged here, and not only the adjusted images 1 to 5 on the front side of the first sheet, but also when the user sets this sheet again in the multi-manual sheet feeding section 1 ''. A mark is also printed to prevent mistakes in the setting direction.

FIG. 8D is a window for prompting the user to set the discharged sheet again in the multi-manual sheet feeding section 1 '', and at that time, the user can easily set the sheet without making a mistake in the setting surface and direction. It is displayed in association with the printed mark. When the user sets paper and presses the start key, the window on the LCD 304 is switched to the window of FIG. 8B, and at that time, the image forming apparatus re-feeds the sheet and uses the electrophotographic process to adjust the adjustment image on the back second surface. Is formed on the same surface of the sheet on which the adjusted image of the first surface is formed, and the sheet on which the toner image is fixed on the surface by the fixing device is discharged to the outside of the apparatus as it is, and the LCD 304 displays the window of FIG. As shown in FIG. 10, a plurality of adjustment images (positional deviation confirmation marks 1 to 5) are formed on the discharged sheet in the direction orthogonal to the transport direction. An enlarged view of these marks is shown next to it.

Each mark has a scale composed of a front image and a back image. The scale of the front and back marks has a so-called vernier scale structure, and is formed by dividing a predetermined interval at a side having a predetermined pitch by a pitch of plus one (minus one). (Specifically, as shown in FIG.
If the front and back alignment accuracy is 0.5 mm, it is necessary to form vernier with a resolution of at least about 0.1 mm, and a line with a 1 mm interval at a distance of 10 mm and a line with a 0.9 mm interval at 9 mm ( 10 / 10-9 / 10 if the vernier is constructed with broken lines for easy identification.
A resolution of = 1/10 = 0.1 can be realized. ) Where the vernier scales match is A in the figure,
It is shown by B and C. The front and back marks 1 to 5 are formed such that the phase of the back image is slightly shifted with respect to the front image. It is possible to visually confirm with which number mark the matching of the scales in the marks is realized, and to know the amount of positional deviation adjustment of the front and back images. The user visually confirms from the misregistration confirmation mark formed on the ejected sheet which mark the scale matches to achieve LC
The number is selected on the screen of D304 in FIG. Based on the selected number, the main body control unit controls the control target so as to adjust by the adjustment amount corresponding to the number, and adjusts the positional deviation of the front and back images.

As the image position adjusting means to be controlled, there are the following various modes. For example, the drive members 40 and 41 of the intermediate transfer member 8 (for example, the drive rolls of the intermediate transfer member if the intermediate transfer member is in the form of a belt) are controlled, and the intermediate transfer member 8 is controlled.
Or the image writing means 15 for the photosensitive drum 13 (for example, in the case of an electrophotographic image forming apparatus, an exposing means for writing an electrostatic latent image or the like) may be controlled. The image writing timing on the photosensitive drum 13 may be adjusted,
Alternatively, the drive timing of the registration roller 7 or the paper feed timing from the paper feed means 1, 1 ', 1''may be adjusted, or these may be combined.

The above-mentioned "adjustment amount corresponding to the number" is the adjustment amount of the image position adjusting means which is the actual control target of the adjustment and corresponds to the adjustment amount of the recording position of the front and back images corresponding to the selected number. May be associated with and prepared in advance in a table or the like. Alternatively, the operator may directly input.

By instructing the main body of the information regarding this adjustment from the operation panel, the image shift between the front and back can be adjusted, and the operator can control the image in the most suitable state by visual inspection.
A good front and back image positional relationship can be obtained.

(Manual Cassette Adjusting Mode) An image forming apparatus having no second sheet conveying direction changing device (flapper) 31 or a manual cassette adjusting mode in which the cassette 1 or 1'is used to make an adjustment will be described. .

FIG. 8E is a window displayed when the manual cassette adjustment mode key 342 of FIG. 7 is pressed, and a window for displaying a message to press the start key 302. When the start key is pressed here, the window shown in FIG. 8B is displayed on the LCD 304 so that the operator can easily understand the situation. At that time, the image forming apparatus feeds the sheet from the sheet feeding unit 1 or 1 ′, forms an adjusted image of the front side on the sheet using an electrophotographic process, and fixes the toner image on the surface by the fixing device. The sheet is discharged to the outside of the apparatus as it is, and the LCD 304 switches to the window of FIG.

FIG. 8C shows the sheet discharged here, and not only the adjustment images 1 to 5 on the front side of the table 1 but also the setting direction when the user sets this sheet again in the cassette 1 or 1 '. A mark is printed to prevent mistakes.

FIG. 8F is a window for prompting the user to set the discharged sheets in the cassette 1 or 1'again, so that the user can easily set the sheets and the direction of the sheets without making a mistake. The cassette position when the device is viewed from the front is highlighted, and the direction in which the device is set in the cassette in the top view is displayed in association with the printed mark. (Here, since the device side recognizes whether the fed cassette stage is 1 or 1 ', the device side designates and displays either 1 or 1'on the screen to be displayed. When the user sets a sheet and presses the start key, the LCD 304 switches to the window of FIG. 8B, and at that time, the image forming apparatus re-feeds the sheet and the sheet is re-fed. A photographic process is used to form an adjusted image on the back side on the same side of the sheet on which the adjusted image on the front side is formed, and the sheet on which the toner image is fixed on the front side by the fixing device is discharged to the outside of the apparatus as it is, and the LCD 304 Displays the window of FIG. Subsequent operations are the same as those in the manual feed adjustment mode, and therefore will be omitted.

(Automatic Adjustment Mode) Regarding the automatic adjustment mode which is possible in an apparatus having a structure having the second sheet conveying direction changing device (flapper) 31 and capable of automatically re-feeding the same surface. explain.

FIG. 8E shows the automatic adjustment mode key 3 of FIG.
This window is displayed when 43 is pressed, and is a window for displaying a message to press the start key 302. If you press the start key here, the LCD
A window shown in FIG. 8B is displayed at 304 to make it easy for the operator to understand the situation. At that time, the image forming apparatus feeds the sheet from the sheet feeding unit 1 or 1 ′, forms an adjusted image of the front side on the sheet using an electrophotographic process, and fixes the toner image on the surface by the fixing device. The sheet, that is, the first sheet conveyance direction conversion device (flapper) 30 or the second sheet conveyance direction conversion device (flapper) 31, is not switched to perform the switchback operation, and the second surface is formed on the sheet surface on which the first surface image is formed. Adjust the image of and discharge it to the outside of the device. When the paper discharge sensor detects paper discharge, LCD3
04 displays the window of FIG. Subsequent operations are the same as those in the manual feed adjustment mode, and therefore will be omitted.

(Other Embodiments) In the above-described embodiment, when the front and back images are aligned by the image position adjusting means, the user makes an adjustment on the operation panel based on the result of visual observation. A description will be given of a device in which a detecting means for detecting this pattern is provided, and the position is automatically adjusted by feeding back to the image position adjusting means based on the detection result of this detecting means. In addition to the above-described configuration, front and back image shift detecting means 32 is added in the paper transport path (FIG. 11).

As an example, a mark as shown in FIG. 13 is used to detect the amount of front and back image shift. This shows a state in which lines are written on both the front and back sides with the same pitch overlapping. A plurality of these detection marks are arranged in the sheet conveying direction in such a manner that the phase of the back surface image line position is gradually shifted with respect to the front surface image line pitch. These lines on the sheet are read using the front and back image shift detecting means 32 of FIG. As a means for realizing this, a device for detecting an optical reflection signal with respect to a line as shown in FIG. 12 is generally used, and a signal High or Low level can be obtained depending on the presence or absence of the line.

As shown in FIG. 13, first, the surface image line
Are written at equal intervals, while the back image line is
After intentionally delaying the initial line by a few lines, the line width is the same as the front image.
The writing of the in is executed. Do this operation
First, extract only the signals that cross the lines of the front image.
And the reference time T₀Can be determined. This reference time
A signal that alternately crosses the front and back lines after the distance is determined
Occurs. Surface signal is T ₁, Back signal T_TwoWhen
The reference time T₀The first difference signal Ts (= T
_Two-T₁) Is the reference time T₀(= T₁) Is shorter,
It is judged that the back side image precedes, and further, this difference signal
The phase that minimizes the signal Ts is determined to be the minimum positional deviation of the front and back images.
You can refuse. Also, the difference signal Ts is
If it lags behind the surface image, the reference signal
Time T₀The difference signal Ts is detected after
Therefore, it can be determined that the image is delayed. C
Transport and read the marks (1, 2, 3 in Fig. 13) in order.
By doing so, the mark having the smallest difference signal Ts is identified.
It Amount of misalignment between the front and back that corresponds to the mark detected here
Based on its detection on the image forming process of the machine body
The amount of feedback is fed back, and the image relationship without front and back misalignment is realized.
can do.

Next, a method of setting the adjustment mode when printing out from the image forming apparatus of the present invention in the adjustment mode by the host computer will be described. First, when the host computer is a PC, it is general that software dedicated to the image forming apparatus is prepared. This software is generally called a printer driver. Also in the image forming apparatus of the present embodiment, a dedicated printer driver is prepared, and various functions such as stapling and double-sided functions of the image forming apparatus can be set.

FIG. 14 shows an example of network connection between the image forming apparatus 100 and host computers (PC1, PC2, PC3, PC4). The image forming apparatus and each host computer can be connected to each other via a network, and the image forming apparatus is connected to each host computer via a network communication I / F 215. When performing printout on each image forming apparatus, each host computer sets a print mode that can be performed on the image forming apparatus by the printer driver described above.

Since the image forming apparatus of the present invention supports the adjustment mode, the adjustment mode is set on the printer driver. In the above-described embodiment, the LCD of the operation unit 219
Although the window displayed in 304 is shown, the printer driver may display the same on the monitor of the host computer to perform the adjustment mode.

Although the network communication has been described as the embodiment, the same can be said for the relationship between one PC and one image forming apparatus. In addition, by allowing the main body to be instructed not only from the operation panel but also from the screen of the PC in this way, the image shift between the front and back can be adjusted, and the operator can control the most appropriate state with the visual state of the operator. A good front and back image positional relationship can be obtained.

In the present invention, assuming that the leading end in the sheet conveying direction is always treated as an image reference, the image reference position on the sheet is substantially the same for the front side mark and the back side mark in each adjustment mode, but the normal double-sided During image formation, the image reference positions on the sheet substantially differ between the front surface and the back surface. Therefore, when creating images on both sides of a sheet, the image forming reference position on the front side is the leading edge (or the trailing edge) in the sheet conveying direction, and the image forming reference position on the back side is the trailing edge (or the leading edge) in the sheet conveying direction. ), The image forming reference position is always set to the same end side in the transport direction in response to the instruction to adjust the image forming position. On the contrary, when creating images on both sides of the sheet, unify the image formation reference positions on the front and back sides to either the leading edge or the trailing edge in the sheet transport direction (always the same edge in the transport direction). In response to an instruction to adjust the formation position, the image formation reference position is set at the leading edge (or the trailing end) in the sheet conveyance direction when forming the front side mark and the image formation reference position when forming the back side mark. It may be a rear end portion (or a front end portion) in the sheet conveying direction.
As a result, the reference end is the same during the double-sided image formation and the adjustment mode, and accurate adjustment is possible.

In the present invention, an image forming apparatus using a so-called intermediate transfer belt has been taken as an example, but other direct transfer image forming apparatuses are also image forming apparatuses using a photoconductor belt. Needless to say, the effectiveness is not impaired at all.

The mark indicating relative positional deviation between the front and back is not limited to this, and any mark that allows the operator to recognize the positional deviation between the front and back or the machine body can be detected.

In this adjustment mode, when the user mode key 305 for setting a common user specification that covers all functions when using any function of the copying machine such as the copy function and the printer function of FIG. 3, is pressed. LCD 30
4 may be included in the items of the screen displayed, and the main body control unit 200 is configured by a microcomputer system including a CPU, a ROM, a RAM, and an input / output interface, and executes the adjustment mode from the operation panel. Although it is configured to be selectable, the execution timing of this adjustment mode may be performed at regular intervals (at power-on, every predetermined number of sheets, etc.).

Further, even a double-sided conveying path, that is, an image forming apparatus having a first sheet conveying direction changing device (flapper) 30 and a second sheet conveying direction changing device (flapper) 31 built therein can be attached and detached. It goes without saying that even a device does not impair its effectiveness.

[0064]

As described above, in the present invention, the deviation amount of the image formed between the front and back surfaces formed by the electrophotographic method is compared by using a single surface on the sheet. Therefore, it is possible to easily and clearly grasp, and based on this amount, it is possible to obtain an image relationship without image shift between the front and back.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing the configuration of an image forming apparatus of the present invention.

FIG. 2 is a block diagram of the present invention.

FIG. 3 is a diagram showing an operating unit of the present invention.

FIG. 4 is a standard screen displayed on the LCD 304 of the operation unit of the present invention.

FIG. 5 is a screen displayed on the LCD 304 of the operation unit of the present invention for specifying the type of both sides.

FIG. 6 is a screen for detailed setting of both sides displayed on the LCD 304 of the operation unit of the present invention.

FIG. 7 is a screen for specifying a double-sided adjustment mode displayed on the LCD 304 of the operation unit of the present invention.

8A to 8F are screens in a double-sided adjustment mode displayed on the LCD 304 of the operation unit of the present invention.

FIG. 9 is a screen for specifying an adjustment amount, which is displayed on the LCD 304 of the operation unit of the present invention.

FIG. 10 is a diagram showing a sheet on which an adjusted image of the present invention is recorded.

FIG. 11 is a vertical cross-sectional view showing the configuration of another image forming apparatus of the present invention.

FIG. 12 is a diagram showing the reading principle of the sensor of the present invention.

FIG. 13 is an explanatory diagram of the automatic adjustment of the present invention.

FIG. 14 is a diagram illustrating a vernier.

[Explanation of symbols]

1 cassette 2 paper feed rollers 3, 4, 5, 6 Transport rollers 7 Registration roller 8 Intermediate transfer belt 9 Secondary transfer section 10 Electrophotographic process unit 12 Image reading device 13 Photoconductor 14 Charger 15 Exposure equipment 16 Developer 17 Transcription device 18 Cleaning device 19 Fixer 20 Inversion section 30 First sheet conveying direction changing device 31 Second sheet conveying direction changing device 32 image reading device

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H027 DA21 DE07 ED16 FA13 GA23                       GB13 GB19                 2H028 BA05 BA16 BB02 BB06                 2H072 AA32 AA36 AB07 BA03 BA12                       CA01 CA02 CA05 CB01 CB03                       CB09                 3F100 AA02 BA17 CA12 CA13 EA02                       EA03 EA14

Claims (10)

[Claims] 1. An image forming apparatus having an image forming unit for forming an image on a fed sheet, wherein a first adjusted image prepared in advance is displayed in response to an instruction to adjust an image forming position. Control for forming a sheet by the image forming unit, and controlling to form the second adjusted image in response to the fact that the surface on which the first adjusted image is formed on the sheet is fed to the image forming unit. An image forming apparatus comprising means. 2. The image forming apparatus according to claim 1, further comprising adjusting means for adjusting an image forming position on the sheet, and adjusting setting means capable of setting an adjustment amount by the adjusting means. The image forming apparatus described. 3. The image forming apparatus according to claim 2, wherein the adjustment setting unit has a display control unit that controls the display of the information about the processing procedure by transiting in screen units. 4. The image forming apparatus according to claim 1, wherein the control unit controls to form at least one set of the first and second adjusted images. 5. The image forming apparatus according to claim 4, wherein the first adjusted image is a scale image having a pitch different from that of the second adjusted image. 6. The image forming apparatus according to claim 5, wherein a vernier scale image is formed by a combination of the first and second adjustment images. 7. The image forming apparatus measures a positional deviation amount in a scanning direction based on the first and second images formed on the same surface, and an image based on a measurement result of the measuring means. The image forming apparatus according to claim 1, further comprising an automatic adjusting unit that adjusts a forming position. 8. The image forming apparatus, when forming an image on both sides of a sheet, sets a front side image forming reference position as a sheet conveying direction front end portion and a back side image forming reference position as a sheet conveying direction rear end side. The image forming apparatus according to claim 1, wherein the image forming reference position is always on the same end side in the transport direction in response to an instruction to adjust the image forming position. 9. The surface of the sheet on which the first adjustment image is formed in order to form the second adjustment image in response to an instruction to adjust the image formation position of the image forming apparatus. The image forming apparatus according to claim 1, further comprising a re-conveying unit that feeds the image to the image forming unit. 10. The surface of the sheet on which the first adjustment image is formed in order to form the second adjustment image in response to an instruction to adjust the image forming position. 2. Removable re-conveying means for feeding the sheet to the image forming section.
Image forming device.