JP2001010179A - Method for setting image forming position, apparatus and method for forming image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always form an image at a normal image position on recording paper on the paper by conducting the step of obtaining a regulating value from a peculiar slanted image position of a sheet supply means for a plurality of the supply means, and storing the obtained regulating value in a nonvolatile memory. SOLUTION: In the apparatus for forming an image by controlling an automatic original feeding means ADF, an image reading means A, a paper feeder D and an image forming means 150 by a control means 100, a write starting position for forming the image on a photosensitive member by an image writer in an image forming means 150 is controlled to control the image forming position on the member. In this case, since the image forming position on recording paper P is largely changed by slanting of the paper P and its value indicates peculiar values for the plurality of the paper feeding means, the regulating values previously stored in a nonvolatile memory 160 are read to meet the characteristics of the respective feeding means and the forming position is changed, thereby suppressing a change of an image position on the paper to a small value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to control of an image forming position for forming an image at a correct position on recording paper.

[0002]

2. Description of the Related Art A high-speed image forming apparatus for forming an image by an electrophotographic system is provided with a plurality of paper feeding means, and accommodates recording papers of various sizes.
An image can be formed on a recording sheet by selecting a recording sheet of a desired size. Further, many image forming apparatuses have a double-sided image forming function of forming images on both sides of a recording sheet.

Many double-sided image forming apparatuses supply a recording sheet to a transfer position and form an image on the surface of the recording sheet.
Double-sided image formation is performed by reversing the front and back of the recording paper and supplying it again to the transfer position to form an image on the back of the recording paper.

[0004]

As described above, the recording paper is supplied to the transfer position from a plurality of paper feeding means, and the recording paper is reversed and recorded again at the transfer position for forming a double-sided image. In an image forming apparatus that supplies paper, a complicated and long recording paper transport path is required, and it is inevitable that the probability of occurrence of trouble in transporting the recording paper increases. Various countermeasures have been taken for troubles such as a paper jam that require the device to be stopped, so that there is no practical problem. However, at present, sufficient measures have not been taken against relatively minor transport failures, such as the recording paper being transported at an angle or the recording paper being slightly offset from the regular transport path.

[0005] As the conveyance path of the recording paper is complicated and long, and various degrees of conveyance failures occur, countermeasures against such minor conveyance failures are desired.
Further, in an image forming apparatus such as a digital image forming apparatus which has a use as a copying machine and a use as a printing machine, it is required to remarkably improve a shift of an image position on a recording sheet. In particular, in a two-sided image forming apparatus, it is an important image forming requirement that the front side image and the back side image are formed at the same position, and the improvement of the recording paper conveyance failure which causes the image position shift is strongly improved. It is coming to be desired.

On the other hand, many digital image forming apparatuses are provided with a non-stacking type back-side image forming conveyance unit without a stacking unit for stacking recording papers, as a back-side image formation conveyance unit. The reason for this is that the digital image forming apparatus uses an image memory, so that it is possible to create a printed material in which one copy is composed of a plurality of pages for each copy. A non-stack system with a small amount and high transfer efficiency is advantageous. However, in the non-stack system, since there is no means for aligning the recording paper during the conveyance, such as the conveyance means for backside image formation having the stacking unit, the probability of occurrence of conveyance failure that stops the apparatus such as a paper jam is low. Although reduced, the inclination of the recording paper and the probability of occurrence of deviation (offset) from the normal conveyance path tend to increase.

For the various reasons described above, it is desired to take measures against the inclination of the recording sheet and the deviation from the normal conveying path, that is, the deviation, which occurs when the recording sheet is conveyed in the image forming apparatus.

As a proposal to meet such a need, there is a technique of providing a sensor for detecting the deviation of the recording paper in the recording paper conveyance path, and correcting the deviation of the recording paper based on information from the sensor. . However, such technology is
It is extremely difficult to make an effective correction for a wide range of recording paper sizes such as 3 to B6R, and to make an effective position correction, it is possible to detect the recording paper transport position with an accuracy of 1 mm or less. In addition to the necessity of a sensor having the above, for example, a CCD, the control becomes complicated, resulting in an increase in cost, and there is a practical problem.

SUMMARY OF THE INVENTION It is an object of the present invention to propose a practically effective countermeasure against a deviation such as a skew of a recording sheet and a deviation from a regular conveyance path.

[0010]

The above-mentioned object of the present invention is achieved by any of the following inventions.

(1) A recording sheet is selected from a plurality of sheet feeding means and supplied to a transfer position of the image forming apparatus, an image is formed on the recording sheet, and an image position peculiar to each of the sheet feeding means is shifted. A first image position detecting step of performing a step of obtaining an adjustment value from the plurality of sheet feeding means, and a first image forming position for storing the adjustment value obtained in the first image position detecting step in a first nonvolatile memory A method for setting an image forming position in an image forming apparatus, comprising a setting step.

(2) An image forming step of transporting the recording paper to the transfer position and forming an image on the recording paper by using the recording paper of various sizes is performed by the transporting means for the backside image formation of the image forming apparatus. A second image position detecting step for obtaining an adjustment value from a deviation of the image position specific to the size, and a second image forming position setting for storing the adjustment value obtained in the second image position detecting step in a second nonvolatile memory A method for setting an image forming position in an image forming apparatus, comprising the steps of:

(3) A plurality of paper feeding means, a first nonvolatile memory for recording a first adjustment value which is predetermined corresponding to each of the plurality of paper feeding means, and based on the first adjustment value. An image forming unit that controls an image forming position of an image formed on a photosensitive member to form an image at a regular position on recording paper supplied from the plurality of paper feeding units. Forming equipment.

(4) Image forming means having control means for controlling the formation of an image on a recording sheet, and conveyance for backside image formation for inverting the recording sheet having an image formed on the front side and conveying it to a transfer position Means, and a second non-volatile memory for storing a second adjustment value corresponding to a change in the size of the recording paper in the back side image formation for forming an image on the back side of the recording paper; In forming, the second
An image forming apparatus that forms an image at a regular position on recording paper of each size by controlling an image forming position based on an adjustment value.

(5) A back-side image forming transport means for inverting the recording paper having an image formed on the front surface and transporting the recording paper toward the transfer position, and stores a second adjustment value corresponding to a change in the size of the recording paper. A control unit that controls an image forming position based on the second adjustment value to form an image on the back surface of the recording paper, thereby controlling each size of the image. The image forming apparatus according to (3), wherein an image is formed at a regular position on the recording paper.

(6) In an image forming method in which recording paper is supplied to a transfer position from a plurality of paper supply units to form an image on the recording paper, a signal indicating which of the paper supply units supplies the recording paper is provided. An image forming method comprising: controlling a writing start position in a main scanning direction in image formation based on the image forming method.

(7) After the recording paper is supplied to the transfer position to form an image on the surface of the recording paper, the front and back are reversed, and the recording paper is supplied again to the transfer position to print the image on the back of the recording paper. An image forming method for forming an image, wherein a writing start position in a main scanning direction for forming an image on a back surface of a recording sheet is controlled in accordance with a size of the recording sheet.

(8) After the recording paper is supplied to the image forming position and an image is formed on the front surface of the recording paper, the front and back sides are reversed,
When the recording paper is supplied again to the image forming position and an image is formed on the back surface of the recording paper, the writing start position in the main scanning direction is controlled according to the size of the recording paper. 6) The image forming method according to the item.

[0019]

FIG. 1 is a diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus includes an image reading unit A that reads an image of a document, an automatic document feeding unit AD that sends one document from a document set placed on a document mounting table, and conveys the document to a reading position of the image reading unit A.
F, an image forming unit B for forming an image on recording paper in an electrophotographic system, an image writing unit C, a paper feeding unit D, and the like.

In the image reading means A, a document conveyed by an automatic document feeding means ADF, which will be described later, is placed on a platen glass 11, and a halogen light source 12a provided on a carriage 12 moving on a guide rail (not shown).
Illuminated by A movable mirror unit 13 provided with a pair of mirrors 13a and 13b moves on a slide rail, and is provided with a mirror 12 provided on a carriage 12.
In combination with b, the reflected light from the original on the platen glass 11, that is, the optical image is led out to the lens reading unit 14. The lens reading unit 14 includes an imaging lens 14a.
And a CCD line sensor 14b as an image pickup means. The optical image corresponding to the image of the original document reflected by the mirrors 12b, 13a, 13b is converged by the imaging lens 14a, formed on the light receiving surface of the CCD line sensor 14b, and formed on the line by the CCD line sensor 14b. Are sequentially photoelectrically converted into electric signals.

When the user presses a start button (not shown) on the operation unit, the carriage 12 provided with a halogen light source 12a and a mirror 12b driven by a motor (not shown) and the movable mirror unit 13 move to one position.
Image data of pages of the original is read by the CCD line sensor 14b.

The image signal of the original image read by the image reading means A, that is, the image data is transmitted to the image processing section 130 (FIG. 2).
), Various image processing such as density conversion, filter processing, scaling processing, and γ correction are performed, and then output to the image writing unit C. Then, the image writing unit C is provided on the photoconductor 16 of the image forming unit B for forming an image by an electrophotographic method.
A latent image is formed according to the input image data. That is, the image writing unit C modulates a laser beam generated by a semiconductor laser (not shown) based on an image signal. The laser beam is scanned by a polygon mirror 15 rotated by a drive motor (no sign), passes through an fθ lens (no sign), and the optical path is bent by a reflection mirror (no sign) to form a surface of the drum-shaped photoconductor 16. The electrostatic latent image is formed on the uniformly charged photoreceptor 16. Writing by exposure of the laser beam on the photoconductor 16 is performed by scanning in the main scanning direction by the polygon mirror 15
Scan writing by scanning in the sub-scanning direction by clockwise rotation indicated by an arrow.

On the other hand, in the image forming section B, the photosensitive member 16, a charger 17 for uniformly charging the photosensitive member 16, a developing device 18 as a developing unit, a transfer pole 19 as a transfer unit, and a separation pole 20 , A cleaning device 21 and a fixing device 22. In the figure, the photoconductor 16 rotates clockwise.
Is uniformly charged by the charger 17 and an electrostatic latent image is formed by the image writing unit C as described above. The charger 17 and the writing section C constitute a latent image forming unit. The electrostatic latent image formed on the photoreceptor 16 is developed by the developing device 18 into a toner image, and the toner image is further transferred onto the recording paper P separately transported by the transfer pole 19. The transferred recording paper P is separated by the separation pole 20, and the toner image is fixed on the recording paper P by the fixing device 22. Further, the photoconductor 16 on which the toner image has been transferred to the recording paper P continues to rotate, is cleaned by the cleaning device 21, and is prepared for the next toner image formation.

The paper supply section D includes paper supply means 23a to 23e for supplying the recording paper P for each size or direction, and a double-sided image forming unit (hereinafter, referred to as a reverse side) for inverting the recording paper P when forming a double-sided image. ADU 24). The sheet feeding unit 23a has a sheet feeding tray 230a (tray 1) and a sheet feeding roller 231a, and the sheet feeding units 23b to 23d similarly have sheet feeding trays 230b to 230d (tray 2 to 4) and sheet feeding rollers 231b to 231d. Having. Paper feeding means 23e
Denotes a manual sheet feeding unit, which includes a sheet feeding table 230e and a sheet feeding roller 231e. In image formation, the paper feed roller 2
The recording paper P selected from 31a to 231e is sent out and supplied to the registration rollers 232. The registration roller 232 operates in synchronization with image formation on the photoconductor 16,
This is a synchronous conveyance unit that conveys the recording paper toward a transfer position formed by the transfer pole 19.

In the case of single-sided image formation, the sheet feeding means 23a to 23a
The toner image is sequentially transferred and fixed onto one side of the recording paper P supplied from 23d, and is discharged onto the recording paper discharge tray 26. On the other hand, in the case of double-sided image formation, the recording paper P transferred with the toner image transferred and fixed to one side is turned downward by the switching claw 25 disposed immediately after the fixing device 22 in the recording paper conveyance path. Guided to ADU24. ADU
At 24, the transport direction of the transported recording paper P is reversed,
Further, by reversing the recording paper P, the recording paper P is reversed, and is fed to the photoreceptor 16 in the same manner as the paper feeding from the paper feeding means 23a to 23e. Then, the toner image formed based on the image data on the back side of the document is transferred and fixed, and a double-sided image formation is obtained. ADU24 is sent recording paper P
Are sequentially turned upside down, and are conveyed toward the registration roller 232, and do not include an accumulation unit for accumulating the recording paper P.

In the digital image forming apparatus of the present embodiment, an automatic document feeder ADF for automatically conveying a document on the platen glass 11 is provided above the image reading means A. When an image is formed using the automatic document feeder ADF, a plurality of documents (hereinafter, referred to as a document set) are placed on a document table (with no reference sign) with the image side of the document facing down, When the start button is pressed, the lowermost document is sequentially fed one by one from this document set, and is automatically conveyed to a predetermined position on the platen glass 11 in order, and the image of the document is read as described above. Then, the read document is removed from the platen glass 11 and discharged onto the document discharge tray 28.

FIG. 2 shows a control system and an image data processing system of the image forming apparatus shown in FIG. In the figure, thick arrows indicate the flow of image data, and thin arrows indicate the flow of control signals. The automatic document feeder ADF, the image reader A, and the paper feeder D are controlled by the controller 100 and operate as described above. Reference numeral 110 denotes setting of various functions and operation modes of the image forming apparatus, for example, image forming conditions such as the number of copies, magnification, density, single-sided / double-sided, post-processing such as stapling and punching, and setting of image forming reservation. It is a setting unit to accept. A print 120 converts image data from an image information output device such as a personal computer into a format processed by the image forming apparatus, outputs the image data, and transmits and receives control signals between the image information output device and the image forming device. A controller 130 is an image processing unit that performs image processing such as a filtering process, a scaling process, and a density conversion process on the image data from the document reading unit A. 140 is a print controller 1
20 is a storage unit that performs error diffusion processing and image compression processing on image data from the image processing unit 20 or the image processing unit 130 and stores the data in an image memory. Reference numeral 150 denotes an image forming unit that forms an image on the recording paper P, and includes the photoconductor 16, a charger 17, a developing unit 18, a transfer pole 19, and an image writing unit C in FIG. By controlling the image writing section C of the image forming means 150 by the control means, the writing start position for forming an image on the photosensitive member is controlled, whereby the image forming position on the photosensitive member is controlled, and The image forming position is controlled.

In the present embodiment, four paper feed trays 230a to 230d are provided, and these paper feed trays hold recording paper of A3 to B6 sizes in the transport direction in the AB size series. The paper can be stored in a horizontally long state in which the sides are matched or a vertically long state in which the short sides are matched in the transport direction. The paper feed tray 230e is a so-called universal type paper feed tray, on which recording paper of an irregular size as well as a standard size can be placed. Each of the paper feeding units 23a to 23e is provided with a size sensor, and detects the size of the stored or placed recording paper and whether the recording paper is horizontal or vertical.

FIG. 1 shows the transport paths 233a, 233b and 233.
As shown by c, 233d, and 233e, the transport paths from the respective sheet feeding means to the registration rollers 232 are different, and the lengths of the transport paths are also different. Since the recording paper P is supplied to the registration rollers 232 via the conveyance paths having different lengths as described above, the recording paper supplied from each of the paper feeding units 23a to 23d may exhibit a unique bias. It turned out from the experiment. In addition, it has been found that the manual sheet feeding unit 23e exhibits unique characteristics different from other sheet feeding units. FIG. 3 shows the bias characteristics of each sheet feeding means. H1 to H5 indicate bias characteristics of the sheet feeding units 23a to 23e, respectively. The offset shown in FIG. 3 is a plot of the position of the image on the recording paper obtained by repeatedly forming an image on the recording paper P. In FIG. 3, the positional deviation from the reference position R1 is plotted on the horizontal axis, and each position is plotted. Are plotted with the number of times of image formation in FIG. As is clear from FIG. 3, when the reference of the image forming position is a fixed position R1, the image forming position on the recording paper P is largely changed by the deviation of the recording paper P, but the paper feeding units 23a to 23e. And the image forming position is changed in accordance with the characteristics of each paper feeding unit, so that the fluctuation of the image position on the recording paper P can be suppressed to a small value.
In particular, it can be seen that the image deviation on the recording paper P can be suppressed to an extremely small value by adjusting the image forming position to the peak position of the deviation characteristic of the paper feeding units 23a to 23d.

In the present embodiment, the fluctuation of the image forming position due to the deviation of the recording paper P is reduced by utilizing the characteristics of the paper feeding means 23a to 23e as described above. According to the experiment, it was possible to suppress the fluctuation of the image position within the range of 1.5 mm.

FIG. 4 shows the bias characteristics of the recording paper P in the back side image formation. FIG. 4 also shows a change in the number of image formations for each position, with the horizontal axis representing the deviation of the image formation position from the reference position R2. The non-stack type back image forming conveyance unit 240 is a unit that conveys a long conveyance path that starts at the registration roller 232 and returns to the start point via the fixing device 22 and the ADU 24. However, it is difficult to make the traveling direction controllable exactly the same between a large size such as A3 size and a small size such as B6 size. In the case of a small-sized recording paper P, the number of rollers for regulating the front end and the rear end of the recording paper P is reduced, and it is inevitable that the recording paper P is easily shifted.
FIG. 4 shows the bias characteristics of the recording paper P of various sizes obtained from the experiment. J1 to J5 are A3, B4, and A4, respectively.
The R, A4, and B6 sizes show offset characteristics. The experimental results shown in FIG. 4 show that, although there is variation between recording paper sizes, each paper size has a unique offset, and the image position is adjusted to the peak position of each characteristic according to each recording paper size. Thus, it can be seen that the variation of the image forming position on the recording paper can be suppressed.

In the present embodiment, the image forming position is controlled in consideration of the deviation of the recording paper P based on the above experimental results, and the fluctuation of the image position on the recording paper is suppressed.
According to this embodiment, an image of sufficient quality can be obtained as a document for ordinary use such as office work.

Next, a description will be given of an adjustment process for the deviation of the recording paper in the case of configuring the image forming apparatus according to the embodiment of the present invention with reference to FIG. The adjusting step includes a front image position adjusting step G1 and a rear image position adjusting step G2. As a first step of the front surface image formation adjustment step G1, a batch adjustment S1 for all trays is first performed. In the first batch adjustment of all trays S1, a reference value a determined by design is set.

Next, in the tray 1 individual adjustment S2, paper is fed from the paper feeding means 23a provided with the tray 1, and the writing start position in the main scanning direction in writing by the laser is set to the reference value a. An image is formed. From the image position formed on the recording paper P, an adjustment amount a1 for the paper feeding unit 23a is obtained. Such a process is performed for the sheet feeding units 23b to 23d including the trays 2 to 4 and the manual sheet feeding unit 23e to obtain adjustment values a2 to a5 for the respective units. Using the obtained adjustment values a1 to a5, the sheet feeding unit 23
An all tray collective adjustment S1 for adjusting the entirety of a to 23e is performed. Then, after the overall adjustment, individual adjustment values a1 to a
5 is performed. By repeating such a process, the deviation characteristics H1 to H5 of the respective sheet feeding units 23a to 23e shown in FIG. 3 are obtained. H1 is the paper feeding means 23
a, H2 is the paper feeding means 23b, and H3 is the paper feeding means 23c.
H4 is a bias characteristic of the paper feeding means 23d, and H5 is a bias characteristic of the paper feeding means 23e. Based on the offset characteristics H1 to H5, adjustment values a1 to a5 with respect to the reference value a of each sheet feeding unit are determined.

The number of repetitions of all-tray collective adjustment S1 to manual-feed individual adjustment S6 in the front surface image position adjustment step G1 is determined in advance through a preliminary experiment. You can also.

The above-described step of determining the adjustment values a1 to a5 is a first image position detecting step of detecting an image position unique to each of the sheet feeding units 23a to 23e.

The adjustment values detected in the first image position detection step, that is, the adjustment values a1 to a5 for each of the sheet feeding means 23a to 23e are stored in a nonvolatile memory 160 as a first nonvolatile memory (first nonvolatile memory 160). Image forming position setting step).

Based on the adjustment values a1 to a5 obtained in the first image position detecting step, each of the sheet feeding means 23a to 23
It is also possible to derive an expression for adjusting the image position for e, store the expression as an adjustment value in the nonvolatile memory 160, and use it for controlling the image position described later.

The backside image position adjustment step G2 includes a backside batch adjustment T1, an individual adjustment T2 for the maximum size A3, an individual adjustment T2 for the large size B4, an individual adjustment T4 for the medium size A4R and B5R, and a small size. An adjustment T5 for certain A4 and B5 and an adjustment T6 for an extremely small size smaller than B5 are performed. In the first batch adjustment T1, a reference value b determined by design is set.

Next, based on the reference value b, an image is formed using A3 size recording paper. By this image formation, A3
The adjustment value b1 for the recording paper of the size is obtained. The above procedure is performed using large-sized recording paper, medium-sized recording paper, small-sized recording paper, and extremely small-sized recording paper, and individual adjustment values b1 to b5 corresponding to each size are obtained. As in the front image forming position adjustment step G1, the backside batch adjustment T1 to T1
By repeating the backside minimum size adjustment T6, the bias characteristics of the recording paper of each size shown in FIG. 4 can be obtained. J1 is a maximum size, J2 is a large size, J3 is a medium size, J4 is a small size, and J5 is an extremely small size bias characteristic. From these offset characteristics, the adjustment value b1 for the A3 size, the adjustment value b2 for the large size, and the adjustment value b for the medium size
3. An adjustment value b4 for the small size and an adjustment value b5 for the very small size are determined. The step of determining the adjustment values b1 to b5 is a second image position detection step.

The adjustment values detected in the second image position detection step, ie, the adjustment values b1 to b5 for each size, are stored in the nonvolatile memory 160 as the second nonvolatile memory (second image forming position setting step). .

Based on the adjustment values b1 to b5 obtained in the second image position detection step, an image position adjustment expression for each size is derived, and the expression is used as an adjustment value in the nonvolatile memory 1
60, and can be used for controlling an image forming position described later.

FIG. 6 shows the control in the image forming process which is performed based on the adjustment values created in the adjustment process of FIG. 5 and stored in the nonvolatile memory 160. FIG. 6 shows an example of a process of forming a double-sided image on A4 size recording paper P to form five images. In the present embodiment, the sheet feeding unit 23
a to 23e, the recording paper P is conveyed,
At the transfer position of the transfer pole 19, an image is formed on the front surface of the recording paper P, and the process of transporting the image by the reverse image forming transport unit 240 is performed a predetermined number of times.
First, a predetermined number of recording papers P are fed into zero. The number of recording papers P to be sent is predetermined according to the recording paper size. Five sheets have a length in the transport direction of A4 or less, and three sheets have a length in the transport direction exceeding A4.

Next, the recording paper P is fed to the back image forming transport means 240, that is, the front image formation is stopped, and the recording paper P on which the image is formed on the front surface is transferred from the back image forming transport means 240 to a registration roller. 232 to perform backside image formation. After the back image is formed on all of the five recording papers P in the back image forming conveyance unit 240, the conveyance is performed from the selected sheet feeding unit to form the front image. By repeating the unit for forming the front surface image and the back surface image on the predetermined number of recording sheets P, double-sided image formation is performed on a large number of recording sheets P.

A4 paper (F) from tray 1 in FIG.
1) The step of forming the image on the front surface of the recording paper P by performing the reading (F2) from the nonvolatile memory 160 at the laser writing start position and the front surface image forming process (F3) up to the set number of sheets includes This is a step of sending the recording paper P to the conveying means 240. Based on F2, the control of the image forming position, that is, the control of the laser writing start position in the main scanning direction is performed based on the adjustment value for the tray 1 stored in the nonvolatile memory 160. This control is a control in which the position of the value obtained by adding the adjustment value a1 to the reference value a from the detection signal of the index sensor (not shown) is used as the writing start position in the main scanning direction.
As a result, a toner image is formed on the photoreceptor 16 at a position shifted by a1 from the reference value in the main scanning direction, and an image is formed in accordance with the sheet feeding characteristics of the tray 1. An image is formed at the image position.

At the stage where five front-side images have been formed and the five recording sheets P have been sent to the back-side image forming conveyance means 240, the recording sheets P from the back-side image formation conveyance means 240 to the registration rollers 232. Is carried out, and the back side image formation is started.

The conveyance of the recording paper from the back image forming conveyance means 240 (A5 to reconvey F5), the reading from the nonvolatile memory 160 at the laser writing start position (F2), and the formation of the back image (F7) are five sheets. This is performed on the recording paper P to complete the double-sided image formation. Based on F6 in the back side image formation, the control of the image forming position, that is, the control of the laser writing start position in the main scanning direction corresponds to the tray 1 stored in the nonvolatile memory 160 and the adjustment value corresponding to the A4 size. It is performed based on. This control is a control in which a position of a value obtained by adding a1 + b3 to the reference value a as an image forming position is a writing start position in the main scanning direction. As a result, a toner image is formed on the photosensitive member 16 at a position shifted by a1 + b3 from the reference value in the main scanning direction. An image is formed in accordance with the shift characteristic, and an image is formed at a regular position on the back surface of the recording paper P.

In the case of forming many images exceeding five sheets in the case of A4 size, and more than three sheets in the case of large size such as A3 size and A4R (horizontal in the conveying direction), FIG. Are repeated in steps F1 to F8.

[0049]

According to the first aspect of the present invention, it is possible to manufacture an image forming apparatus which always forms an image at a regular image position on a recording sheet supplied from a plurality of sheet feeding means. Was.

According to the second aspect of the present invention, it is possible to manufacture an image forming apparatus capable of always forming a back image at a regular image position on recording paper of various sizes.

According to the third aspect of the present invention, there is provided an image forming apparatus which always forms an image at a regular image position on a recording sheet supplied from a plurality of sheet feeding means.

According to the fourth aspect of the present invention, there is provided an image forming apparatus capable of always forming a back side image at a regular image position on recording paper of various sizes.

According to the fifth aspect of the present invention, when a plurality of paper feeding means are selected and used to form a double-sided image on recording paper of various sizes, an image is always formed at a regular image position on the recording paper. An image forming apparatus has been realized.

According to the sixth aspect of the present invention, it is possible to always form an image at a regular image position on a recording sheet supplied from a plurality of sheet feeding means.

According to the seventh aspect of the present invention, it is possible to always form a back image at a regular image position on recording paper of various sizes.

According to the eighth aspect of the present invention, when a plurality of paper feeding means are selected and used to form a double-sided image on recording paper of various sizes, an image is always formed at a regular image position on the recording paper. It became possible.

Moreover, the control according to the present invention does not require a sensor or the like for measuring the traveling position of the recording paper with high accuracy, and therefore can be performed at low cost.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a control system and an image data processing system of the image forming apparatus according to the embodiment of the present invention.

FIG. 3 is a graph showing a bias characteristic of a sheet feeding unit.

FIG. 4 is a graph showing the bias characteristics of recording paper of various sizes in back side image formation.

FIG. 5 is a flowchart illustrating an adjustment process for a deviation of recording paper.

FIG. 6 is a flowchart illustrating an image forming process according to the embodiment of the present invention.

[Explanation of symbols]

 23a, 23b, 23c, 23d, 23e Feeding means 100 Control means 150 Image forming means 160 Non-volatile memory 240 Backside image forming conveying means

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Ryuji Okutomi 2970, Ishikawa-cho, Hachioji-shi, Tokyo Konica Corporation F term (reference) 2C058 AB16 AB23 AC08 AF04 AF17 AF20 GB17 GB30 GB47 2C061 AP04 AQ06 AR03 AS02 MM06 MM07 MM08 MM13 MM24 MM29 2H028 BA14 BB06

Claims (8)

[Claims] An image forming apparatus supplies a recording sheet to a transfer position of an image forming apparatus by selecting a recording sheet from a plurality of sheet feeding units, forms an image on the recording sheet, and adjusts an image position unique to each of the sheet feeding units. A first image position detecting step of performing a step of obtaining an adjustment value for the plurality of paper feeding units; and a first image position detecting step of calculating the adjustment value obtained in the first image position detecting step.
A method for setting an image forming position in an image forming apparatus, comprising a first image forming position setting step of storing the image forming position in a nonvolatile memory. 2. An image forming process in which a recording sheet is conveyed to a transfer position and an image is formed on the recording sheet by using a recording sheet of various sizes by a back image forming conveying means of the image forming apparatus. A second image position detecting step of obtaining an adjustment value from a deviation of an image position peculiar to the image processing; and adjusting the adjustment value obtained in the second image position detecting step to a second image position.
A method for setting an image forming position in an image forming apparatus, comprising a second image forming position setting step of storing the image forming position in a nonvolatile memory. 3. A plurality of paper feeders, a first non-volatile memory that records a first adjustment value that is predetermined for each of the plurality of paper feeders, and based on the first adjustment value. Image forming apparatus comprising: a control unit configured to control an image forming position of an image formed on a photosensitive member to form an image at a regular position on recording paper supplied from the plurality of paper feeding units. apparatus. 4. An image forming means having a control means for performing control for forming an image on a recording sheet, and a reverse-side image forming conveying means for inverting a recording sheet having an image formed on a front side and conveying the recording sheet toward a transfer position. And in backside image formation for forming an image on the backside of the recording paper,
A second nonvolatile memory for storing a second adjustment value corresponding to a change in the size of the recording paper, wherein the control unit controls an image forming position based on the second adjustment value in backside image formation. An image forming apparatus that forms an image at a regular position on recording paper of each size. 5. A back-side image forming conveying means for inverting a recording sheet having an image formed on its front side and conveying it to a transfer position, and stores a second adjustment value corresponding to a change in the size of the recording sheet. The control unit controls the image forming position based on the second adjustment value to form an image on the back surface of the recording paper, thereby controlling the size of each size. 4. The image forming apparatus according to claim 3, wherein an image is formed at a regular position on the recording paper. 6. An image forming method in which a recording sheet is supplied to a transfer position from a plurality of sheet feeding units to form an image on the recording sheet, based on a signal indicating which of the sheet feeding units supplies the recording sheet. Controlling the writing start position in the main scanning direction in image formation. 7. After the recording paper is supplied to the transfer position to form an image on the front surface of the recording paper, the front and back are reversed, and the recording paper is supplied again to the transfer position to form an image on the back surface of the recording paper. An image forming method, comprising: controlling a writing start position in a main scanning direction for forming an image on a back surface of a recording sheet in accordance with a size of the recording sheet. 8. After the recording paper is supplied to the image forming position and an image is formed on the front surface of the recording paper, the front and back sides are reversed, and the recording paper is supplied again to the image forming position and the rear surface of the recording paper is supplied. 7. The image forming apparatus according to claim 6, wherein a writing start position in the main scanning direction is controlled according to a size of the recording paper when forming an image.
2. The image forming method according to 1.,