JPH063885A - Image forming device - Google Patents

Abstract

PURPOSE:To accurately coincide registrations at separate stations at all times even when a mechanical member changes with the lapse of time. CONSTITUTION:When an image pattern is directly formed on carried form PA by a pattern forming means, a CCD sensor part 10 repeatedly reads the registration-correction image pattern on the paper PA while adjusting the light quantities of illuminating means 6 and 7, and the pulse motor, etc., of a printer controller part CONT independently correct transfer position deviation of the drums 2, 3, 4, and 5, respectively, based on the corrected quantities calculated by an arithmetic means.

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 for sequentially superposing images formed on a plurality of image bearing members arranged side by side on a recording medium to be conveyed, and more particularly to each image bearing device. The present invention relates to an image forming apparatus capable of correcting a positional deviation on a recording medium that is formed and transferred on a body.

[0002]

2. Description of the Related Art FIG. 5 is a sectional view for explaining the structure of an image forming apparatus of this type. For example, in a laser beam printer including a reader section 101 and a printer section 102, a photosensitive drum 202 to be an image carrier is formed. A case of a full-color printer including 205 is shown.

In the figure, reference numeral 103 denotes a paper feeding unit, which stores paper as a recording medium, and the paper is conveyed to a registration roller arrangement position by driving a paper feeding roller, and thereafter, the transfer belt 20.
1 conveys at a constant speed. The RCON is a reader controller that controls the reading process (color separation process, shading correction, etc.) of the document image, and outputs the image-processed digital image information to the printer controller PCON. SCA is a scanner and printer controller PCO
Each of the laser beams modulated based on the image signal (VDO) output from N is scanned and exposed on each of the photosensitive drums 202 to 205 via a scanning mirror to form a desired electrostatic latent image.

The reader unit 101 is provided with an image reading means (not shown), for example, an image pickup device such as a CCD, which reads color information on a document while performing color separation, performs predetermined image processing, and then digitally processes image information. Is output to the printer controller PCON. Then, the printer controller PCON scans and exposes each laser beam modulated based on the input image signal (VDO) onto each of the photosensitive drums 202 to 205 via the scanning mirror to form a desired electrostatic latent image. The image is formed, visualized by a developing unit (not shown), transferred and fixed on the conveyed paper, and a color image is output.

By the way, in the image forming apparatus having the configuration as shown in the drawing, it is necessary to perform registration correction in order to match the registration for each color, and the correction pattern image formed on each image carrier is For example, it is transferred onto the transfer belt 201, each correction pattern is read by an image sensor such as a CCD (not shown), and the driving of an actuator that corrects the registration deviation of each image carrier is controlled to arrange a scanning mirror that constitutes a scanner unit. Was adjusted to correct misregistration.

[0006]

However, since the transfer belt 201 may deteriorate due to scratches and stains due to its use, the correction pattern transferred to the transfer belt 201 and the scratches and stains are present close to each other. In such a case, the correction pattern on the transfer belt 201 cannot be detected by distinguishing it from scratches or stains on the transfer belt 201, and the registration correction is executed based on the correction pattern information that is erroneously read. There were serious problems such as promoting misalignment.

The present invention has been made in order to solve the above-mentioned problems, and has a configuration in which an image pattern for registration correction is directly transferred and read on a conveyed recording medium while adjusting the reading light amount. An object of the present invention is to obtain an image forming apparatus capable of consistently matching the registration of each station with high accuracy while reliably identifying and detecting the image pattern for registration correction even if mechanical members change over time. To do.

[0008]

SUMMARY OF THE INVENTION An image forming apparatus according to the present invention includes a pattern forming means for forming an image pattern for registration correction of each image carrier on a recording medium fed and conveyed, and the pattern forming means. Image reading means for reading the image pattern formed on the recording medium, image processing means for performing a predetermined image processing on the image pattern data output from the image reading means, and an image image-processed by the image processing means A calculation means for calculating the registration correction amount for each image carrier based on the pattern data, a light amount variable means for variably adjusting the illumination light amount of the illumination means based on the registration correction amount calculated by the calculation means, and Based on the registration correction amount calculated by the calculation unit while being variably adjusted by the light amount adjustment unit It is provided with a correction means for correcting the registration of the image carriers.

[0009]

In the present invention, when directly formed on the recording medium conveyed by the pattern forming means, the image reading means reads the image pattern for registration correction on the recording medium. Then, after the image processing means performs image processing on the image pattern data output from the image reading means, the calculating means calculates the registration correction amount for each image carrier based on the image pattern data subjected to the image processing. Here, when the light quantity varying means variably adjusts the illumination light quantity of the illuminating means based on the calculated correction quantity, the image pattern for registration correction of the image reading means is read again, and a similar correction quantity is calculated. , The correction means individually corrects the transfer position deviation of each image carrier,
It is possible to match the registration for each image carrier.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of an essential part for explaining the structure of an image forming apparatus showing an embodiment of the present invention.

In the figure, reference numeral 1 is a transfer belt, which is conveyed at a constant speed in the arrow direction by a drive roller 42 which is rotated by the drive of a belt motor 15. Reference numerals 2 to 5 denote photosensitive drums, which are individually driven by the drum motors 11 to 14 and uniformly charged by a charging unit (not shown).
The laser light L1 to L4 optically modulated by each video signal individually output from the printer controller is used for exposure. The latent images formed on the photosensitive drums 2 to 5 are visualized in this order by a developing unit including magenta, cyan, yellow, and black developers, and the respective color images are transferred to the recording medium on the transfer belt 1. Then, a color image is formed. Reference numerals 6 and 7 denote illumination lamps that illuminate the pattern image for detecting the predetermined registration deviation transferred onto the sheet PA on the transfer belt 1. 8
Is an imaging lens, which couples the reflected light of the pattern image for detecting the predetermined registration deviation transferred onto the sheet PA to the CCD sensor unit 10 (which is composed of CCD sensors 10a and 10b described later) via the scanning mirror 9. Make them image. The pattern data for forming the pattern image for detecting the predetermined registration deviation is stored in a memory (not shown), is read at a predetermined timing (see the timing chart shown in FIG. 2), and is read from the scanner SCA to each photosensitive drum 2. To 5 are scanned and exposed, and transferred onto the sheet PA conveyed by the transfer belt 1. CONT is a printer controller unit which controls a normal image forming sequence and a registration correction sequence according to the present invention.
At that time, the printer controller unit CONT executes a predetermined image processing (for example, binarization processing) on the pattern data transferred onto the paper PA read by the CCD sensor unit 10 to perform a calculation means (a registration controller described later). 20) output predetermined pattern data, and when the correction amount calculated by the calculation means (registration controller 20) is inappropriate (exceeds the correction amount adjustment range), the light amount of the illumination lamps 6, 7 Data for increasing / decreasing the illumination amount is set in a driver (not shown) for adjusting., The reading of the pattern transferred on the paper PA is executed again, and the same calculation is repeatedly executed until it converges to the adjustment range of the correction amount.

In the image forming apparatus having the above structure, when the pattern forming means (each of the photosensitive drums 2 to 5 and its peripheral devices) directly forms the recording medium on the recording medium, the image reading means (in this embodiment, the image forming means) is formed. CCD sensor unit 1
0) reads the image pattern for registration correction on the recording medium (paper PA). Then, after the image processing means performs image processing on the image pattern data output from the image reading means, the calculation means (registration controller 20) performs registration on each image carrier based on the image processed image pattern data. Calculate the correction amount. Here, the light quantity varying means variably adjusts the illumination light quantity of the illuminating means (illuminating lamps 6, 7) on the basis of the calculated correction amount, and the image pattern for registration correction of the image reading means is read again to perform the same operation. When the correction amount is calculated, the correction means (each color reflection mirror drive pulse motor 23 to 25, which will be described later) individually corrects the transfer position deviation of each image carrier, and the registrations for each image carrier are matched. It is possible to In addition,
In this embodiment, the light quantity adjusting means, the image processing means, and the calculating means are shown as the functional means of the registration controller 20, but each means may be constituted by independent hardware.

FIG. 2 is a timing chart for explaining the pattern image forming timing on the sheet conveyed by the transfer belt 1 shown in FIG.

FIG. 3 is a plan view for explaining the pattern image reading operation on the sheet conveyed by the transfer belt 1 shown in FIG.

In FIG. 1, PA is a sheet of paper, and pattern images Ma, Cy, Ye, and Bk for registration correction formed on the photosensitive drums 2 to 5 are transferred at the timing shown in FIG. It passes below the position (broken line area in the figure) to be arranged. Since the CCD sensor unit 10 (which is composed of CCD sensors 10a and 10b described later) is composed of an infrared CCD, the black developer (carbon) cannot be read (because carbon black absorbs light). ), The pattern image for black is transferred to the patch surface on which the yellow patch image has been transferred as the base in advance at the yellow station. In this way, when the formation of a pair of one-pattern images on the end side orthogonal to the conveyance direction of the paper PA is completed, the transfer belt 1 is conveyed and the paper PA is conveyed.
Is the CCD sensor unit 10, that is, the CCD sensor 10a,
Pass the position below 10b. At that time, the read data of the pattern image is stored in the bank memory of the registration deviation correction circuit shown in FIG.

FIG. 4 is a circuit block diagram showing a main configuration of the printer controller unit CONT shown in FIG.
The configuration and operation will be described below.

When a pair of one-pattern images is transferred to the end side orthogonal to the conveying direction of the fed paper PA, the pattern images Ma, Cy, Ye, Bk of each color are read by the CCD sensors 10a, 10b. To be Original oscillation clocks β507 and β50 from the registration controller 20
8 is sent to the CCD drivers 18 and 19, clocks (transfer pulse, reset, shift pulse, etc.) β501 and β502 necessary for driving the CCD sensors 10a and 10b are generated, and the clocks of the respective colors read by the CCD sensors 10a and 10b are generated. A pair of pattern images Ma, Cy, Ye, Bk
Pattern image signals β 503 and β 504 for the CCD
Amplification, DC reproduction, A / D conversion, and other processing are performed by the drivers 18 and 19, and digital signals β505 and β506 are obtained.
And the digital signal β 505 is output to the bank memories (BANK 0 to 3) 42 to 45 as the digital signal β.
506 is stored in the bank memories (BANK4 to 7) 46 to 49, respectively. Switching between the bank memories 42 to 45 and the bank memories 46 to 49 is controlled by the bank switching signal β541. Reference numeral 40 is an address counter, and 41 is a region variable setting circuit.

The digital signal β505 is transferred to the paper PA of the transfer belt 1 stored in the bank memories (BANK0 to 3) 42 to 45 or the bank memories (BANK4 to 7) 46 to 49, and the pattern images Ma and C of each color are transferred.
The pattern data β544 of y, Ye, Bk is read by the registration controller 20 for each bank, and the read image data is binarized with a certain threshold value and image-processed. A registration error in the main scanning and sub-scanning directions is calculated with reference to a pattern image of a certain color, for example, a magenta pattern image, based on the image-processed image data, and the calculated result is outside the range of a predetermined value. In this case, for example, the amount of light illuminating the registration image is changed, and the above processing is repeated to calculate the registration deviation, or image processing is performed by changing the binarized threshold value of the read image data. Calculate registration deviation. When the calculated result is within the range of the predetermined value, the electrical image writing timing setting data β509 for each color main scanning and sub scanning is sent to the system controller 21, and the optical path length of the recording laser beam is also sent. The pulse data β511 of each color reflection mirror driving pulse motor 23 to 25 for driving and controlling the reflection mirror provided in the optical path for correcting the change and the change in the optical path is supplied to the mirror motor driver 22. In the mirror motor driver 22, each color reflection mirror drive pulse motor 23 to 25 according to the pulse data β 511 (the laser beam is adjusted by electrically adjusting the arrangement position of the scanning optical system of each photosensitive drum 2 to 5 and the laser beam writing timing). (Functions as a correction means for correcting magnification deviation, inclination deviation, top margin deviation, left margin deviation, etc. of L1 to L4), and supplies current signals β512 to β514 to drive the pulse motors 23 to 25 to drive the reflection mirrors. Adjust the optical placement position. These registration corrections are performed by the activation signal β from the system controller 21.
It is supplied to the registration controller 20 by 510 and executed. Note that β540 is an address signal.

In this way, the CCD sensor 1 receives the registration correction pattern transferred to the fed paper PA.
0a and 10b are read while being discriminated, the deviation amount of the main / sub registration of each pattern image is calculated, and the correction of the optical path length and the optical path change of the laser beams L1 to L4 and the image writing start position correction are individually performed. Each photosensitive drum 2
It is possible to match the registrations in 5.

In the above embodiment, the CCD sensor 10
Since a and 10b are composed of infrared CCD, the case where the original pattern image is transferred after the patch image is pre-transferred by the preceding magenta station in order to read the pattern image (carbon) transferred by the black station has been described. , The reader unit 10 shown in FIG.
Each image pattern transferred to the paper PA by the color image reading CCD or the like provided in the first example (in this case, the pattern image (carbon) transferred at the black station)
Is not transferred as a background) and the registration controller 20 is notified via a predetermined interface (details will be described later), and the yellow patch image forming process can be omitted. C provided in the printer unit 102
The CD sensors 10a and 10b can be omitted. Note that β542 and β543 are read data, β545 is a region designating signal, and β546 is a write / read control signal.

As described above, after the pattern images transferred by the magenta, yellow, cyan, and black stations are transferred onto the paper PA and output (however, the yellow patch is not transferred as the background to the image pattern of the black station). ), And sets it in the reader unit 101 to execute document reading. As a result, the image data that has been color-separated and read is converted into a digital signal by an A / D conversion circuit (not shown), shading-corrected, logarithmically converted, and stored in the bank memories 42 to 49. The registration controller 20 calculates the registration deviation in the main scanning and sub-scanning directions with reference to the pattern image data of a certain color in the image data stored in the bank memories 42 to 49, and the reflection provided in the optical path. Correction is made to the arrangement position of the optical scanning system such as a mirror and the electric image writing timings of the photosensitive drums 2 to 5 in the main scanning and sub-scanning directions, and each photosensitive drum 2
It is possible to make the registrations in 5 to match.

[0022]

As described above, the present invention is formed by the pattern forming means for forming the image pattern for the registration correction of each image carrier on the recording medium fed and conveyed, and the pattern forming means. Based on the image reading means for reading the image pattern on the recording medium, the image processing means for performing a predetermined image processing on the image pattern data output from the image reading means, and the image pattern data processed by the image processing means. Calculating means for calculating the registration correction amount for each image carrier,
Based on the light quantity changing means for variably adjusting the illumination light quantity of the illuminating means based on the registration correction quantity calculated by the calculating means, and the registration correction quantity calculated by the calculating means in the state variably adjusted by the light quantity changing means. Since the correction means for correcting the registration of each image carrier is provided, compared to the case where the image pattern for registration correction is directly transferred to the transport body and read, the influence due to aging is less, and each station It is possible to always accurately detect the transfer position shift of the image formed by.
Further, the user can visually confirm the current registration deviation state in the apparatus main body as an image.

Therefore, it is possible to prevent the correction process which promotes the registration deviation due to the registration correction and to stably form a clear image with no color deviation.

[Brief description of drawings]

FIG. 1 is a main-portion cross-sectional view illustrating the configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a timing chart illustrating a pattern image forming timing on a sheet conveyed by the transfer belt shown in FIG.

FIG. 3 is a plan view illustrating a pattern image reading operation on a sheet conveyed by the transfer belt shown in FIG.

FIG. 4 is a circuit block diagram showing a main configuration of a printer controller section shown in FIG.

FIG. 5 is a cross-sectional view illustrating the configuration of this type of image forming apparatus.

[Explanation of symbols]

 1 Transfer Belt 6 Illuminating Lamp 7 Illuminating Lamp 10a CCD Sensor 10b CCD Sensor PA Paper CONT Printer Controller

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B41J 2/525 G03G 15/01 112 Z // G03G 15/04 116 9122-2H

Claims (1)

[Claims] 1. An image forming apparatus for sequentially superposing images formed on a plurality of image bearing members arranged side by side on a recording medium to be conveyed to form an image. Pattern forming means for forming an image pattern for registration correction, image reading means for reading the image pattern formed on the recording medium by the pattern forming means, and image pattern data output from the image reading means have a predetermined size. Image processing means for performing image processing,
Calculation means for calculating the registration correction amount for each image carrier based on the image pattern data image-processed by the image processing means, and illumination of the illumination means based on the registration correction amount calculated by the calculation means. The light amount variable means for variably adjusting the light amount, and the correction means for correcting the registration of each image carrier on the basis of the registration correction amount calculated by the calculation means in the state variably adjusted by the light amount variable means are provided. An image forming apparatus characterized by the above.