JPH11105344A - Image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system for forming a specified image by superposing a plurality of images in which the image of each color formed by an image recording unit can be aligned inexpensively. SOLUTION: The image forming system comprises a section for storing a plurality of image data for forming a specified image such that each image data can be handled individually, and a plurality of sections for forming individual image of the image data in a specified region, wherein a specified image is formed by superposing the images formed for respective image data. The image forming system further comprises means for adjusting the position for forming each image in the specified region by controlling the writing position of each image data to be stored in the memory section based on the positional shift information between images to be formed in the specified region for each image data.

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 forming a predetermined image by superposing a plurality of images. An electrophotographic image forming apparatus can perform high-speed, high-resolution, and high-quality recording, and various printers such as a laser printer, an LED printer, and a liquid crystal printer have been developed.
In particular, an LED printer, a liquid crystal printer, and the like have fewer mechanical driving parts and can shorten the optical path length as compared with a mechanical scanning laser printer, so that the size of the apparatus can be reduced. In the future, with the progress of semiconductors, solid-state scanning printers can be further reduced in size and cost.

Further, as printers have become more sophisticated, the need for color printers has been increasing, and a high-speed color printer can be realized by using an electrophotographic system capable of high-speed recording.

[0003]

2. Description of the Related Art FIG. 8 shows a configuration diagram of a high-speed color printer using an LED array. This printer device has image recording units U1 to U4 of four primary colors of yellow, magenta, cyan and black. Each image recording unit U includes a photosensitive drum 71, a charger 72, an LED optical system 73, a developing device 74, and a cleaner 75.

Each image recording unit U performs a known electrophotographic recording, and forms a color image on each photosensitive drum 71 with each color toner. The recording paper in the paper cassette 81 is sent out to a recording paper transport system 83 by a pickup roller 82, and is transported below each image recording unit U. When the recording paper passes through each photosensitive drum 71, the color toner image of each photosensitive drum 71 is transferred to the recording paper by the transfer device 76. The fixing device 84 fixes the transferred four color toner images on recording paper and outputs the same to the stacker 86. In this color printer, since each image recording unit U performs image recording in a pipeline manner, high-speed recording is possible.

[0005]

However, since each image recording unit is independent, it is difficult to align images formed by each image recording unit. Unless each image recording unit is installed at a position exactly parallel to the other exposure units, the toner images of the respective colors transferred onto the recording paper do not overlap with each other accurately, deteriorating the image quality. In order to prevent the displacement of each image recording unit, it is necessary to increase the machining accuracy of the entire printer, and there is a problem that the price increases. Also, at the time of adjustment after completion of printer assembly,
It is necessary to perform test recording to perform alignment of each exposure unit, and there is a problem that the adjustment requires time and labor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of simply and inexpensively aligning images of respective colors formed by an image recording unit.

[0007]

An image forming apparatus according to a first aspect of the present invention includes: a storage unit that stores a plurality of image data for forming a predetermined image so as to be able to handle each image data;
A plurality of image forming units for individually forming an image in a predetermined area for each image data according to each image data stored in the storage unit, and superimposing images formed for each image data; An image forming apparatus for forming the predetermined image by combining the image data, wherein each image data stored in the storage unit is stored based on positional deviation information between images formed in the predetermined area for each image data. By controlling the writing position of
The image forming apparatus further includes image forming position control means for adjusting a position at which each image is formed in the predetermined area.

For this reason, it is not necessary to mechanically adjust the positional deviation between the image forming units, and the positional deviation of the image formed by each image forming unit can be changed when the image data is stored in the storage unit. Since the correction is performed by controlling, there is no need to perform mechanical adjustment, and it is possible to easily correct the displacement between the images and to provide an inexpensive device. Also, the second
The image forming apparatus according to the present invention further includes the image forming apparatus according to the first aspect, wherein each of the plurality of image forming units includes a plurality of image forming elements for forming a dot image in the predetermined area. It has an image forming element row, and is configured to form an image in the predetermined area for each image forming element row, and the storage section stores a dot image corresponding to each image forming element of the image forming element row. Has a line buffer in which information indicating whether or not to form is formed, and, under the control of the image forming position control means, stores information indicating whether to form the dot image written in the line buffer. The storage position is configured to be controlled.

With this configuration, the positional deviation between the images formed by the image forming units is corrected in the arrangement direction of the image forming elements in accordance with the arrangement of the image forming elements in the image forming unit. It becomes possible.

[0010]

FIG. 1 is a block diagram showing an embodiment of the present invention.
In the figure, 31 is an image memory, 10 is an exposure position control circuit, 2
0 is a control timing generation circuit, 40 is an LED array, and the exposure position control circuit 10 corresponds to a recording position control means. This configuration diagram shows one image recording unit of a color printer. A color printer having four image recording units has the same configuration for each image forming unit.

The image memory 31 is located in the host device or the printer main body and stores image data. The image data is stored at two levels, that is, whether each dot is recorded or not, and does not perform gradation recording. The exposure position control circuit 10 includes a register 1, an exposure position setting switch 12, a down counter 13, and a register control circuit 14. The exposure position setting switch 12 corresponds to a recording position setting unit. The control timing circuit 20 generates control signals such as a dot clock and a line clock.

The two line buffers 33a and 33b store one line of image data. The buffer switch 32 selects a line buffer for writing image data, and the buffer switch 34 selects a line buffer for sending an image pattern to the LED array 40. When image data is written to one line buffer, the other line buffer controls the buffer switches 32 and 34 so that the image data is sent to the LED array 40.

As shown in FIG. 2, the LED array 40 includes a shift register circuit 41, a latch circuit 42, a driver circuit 43,
It is composed of an LED element 44. The LED array has, for example, 4480 × 1 LED elements arranged in one line, and performs recording in line units. Image data is serially transferred from the line buffer 33a or 33b to the shift register circuit 41, and when one line of image data is stored in the shift register circuit 41, the image pattern is latched by the latch circuit 42, and the driver circuit 43 causes the LED element to emit light according to the latched image data.

FIG. 3 is a timing chart for explaining the operation of this embodiment. Except for the register clear signal, each timing signal is described in positive theory. Hereinafter, the operation of this embodiment will be described with reference to FIGS. The control timing generation circuit 20 outputs a line clock a and a dot clock b. When the line clock a is input to the LOAD terminal of the down counter 13 as the counter load signal c, the data set in the exposure position setting switch 12 is read into the down counter 13.

In this embodiment, "5" is loaded. The down counter 13 counts down according to the dot clock b, and sends out the CY output d when the count value becomes zero. The register control circuit 14 sends a register clear signal e to the register 11 until the CY output d is input. Zero is set in the register 11 while the clear signal e is in the clear state, and image data corresponding to a blank is output to the line buffer. The line buffer stores blank data according to the dot position address sent from the control timing generation circuit 20.

When the down counter 13 becomes zero and sends out the CY output d, the register control circuit 14 sets the register clear signal e to a non-clear state. Register clear signal e
Is ANDed with the dot clock by the AND circuit 21 and then sent to the image memory 31 as a data request signal g. The image memory 31 sends the head of the line, that is, the 0th data, to the register 11 in response to the input of the line start signal g, and thereafter sequentially sends out image data every time the data request signal g is input. The contents of the register 11 are zero while the register clear signal e is in the clear state, and the data sent from the image memory 31 is set hereafter.
The set data is stored in the line buffer 33a or 33.
b.

By the above operation, the set number of blank data is inserted at the head of the line, and the image to be recorded moves to the right as a whole. By setting individual exposure positions so as to correct the deviation of the LED array between the image forming units, the deviation of the recorded image in the line direction is corrected. FIG.
Is a configuration diagram of another embodiment. In the above-described embodiment, a printer that prints one dot at two levels, that is, whether or not one dot is printed, but this embodiment describes a printer that prints one dot at a plurality of gradations (four levels in this embodiment). I do.

FIGS. 4 and 5 show an example of a printer for recording one dot at four levels. In this embodiment, one-dot image data is stored in two bits, and data is read from the image memory 31 in units of eight bits. In the present embodiment, in addition to the exposure position control, variation compensation of the LED array 40 is also performed. The conversion table 34 generates corrected gradation data from the gradation data read from the image memory 31 and the correction data stored in the variation compensation ROM 35. The generated correction gradation data is the number of light emission of the LED element. One line is divided into a plurality of sub-lines, and the LED elements emit light until a required gradation is obtained in synchronization with the sub-line address 94 sent from the control timing generation circuit 20.

FIG. 5 is a block diagram of the position control circuit of the present embodiment, and FIG. 6 is a timing chart for explaining its operation. This will be described below with reference to FIGS. Register 11
Stores gradation data of 8 bits, that is, 4 dots, read from the image memory 31. The control timing ordering circuit 20 outputs a dot clock r, a line clock p, and the like. The dot clock r corresponds to four dots of image data. The line clock p is input to the down counter 13 as a counter load signal s, and the upper pits excluding the lower 2 bits of the set value of the exposure position setting switch 12 are loaded. This is because reading of image data is performed in units of 4 dots. In this embodiment, “5” is set in the exposure position setting switch 12, and “1” is loaded in the down counter 13.

The lower two bits of the exposure position setting switch 12 are input to the barrel shift register 15. Since the data transfer is in units of 4 dots, the number of inserted blank data is 4
, The contents of the register 11 may be transferred to the line buffer as it is. However, if the number of inserted blank data is not a multiple of 4, the contents of the register 11 must be shifted and transferred to the line buffer, and the barrel shift register 15 is required. In this embodiment, “5” is set in the exposure position setting register 12, and “1” is input to the barrel shift register 15. The barrel shift register 15 shifts right by one dot, that is, two bits,
Transfer to line buffer. At the time of right shift, the data pushed out of the shift register 15 in the previous shift is rotated and enters the left side of the shift register 15.

FIG. 8 explains the operation of the barrel shift register in this embodiment. In the first column,
In response to the line start signal v, the image memory 31 stores the image data a _{0 to} a ₃ of the first four dots of the line in the register 11.
To send to. At this time, the register 11 receives the clear signal u and is cleared to zero. After the contents of the register 11 are stored, the barrel shift register 15 shifts image data for one dot, that is, two bits to the right. At this time, the barrel shift register 15 is in the initial state, and zero is rotated on the left side.

In the second column, the image memory 31 stores data
The next four dots of image data b are obtained by the manual operation of the request signal w.
₀~ B_ThreeIs sent. Register 11 stores image data a₀
~ A _ThreeIs set. The barrel shift register 15 is a
₀~ A_ThreeAfter 2 is set, right shift of 2 bits is performed.
Along with the blank image data
Insert mariju zero to the left.

[0023] In the third column, likewise from the image memory 31 is image data c0 -C3 is sent, the image data b ₀ ~b ₃ is set in the register 11. After b _{0 to} b ₃ are set in the barrel shift register 15,
Performs right shift of 2 bits, inserts the image data a ₃ of expelling the previous shift to the left. As described above, even in the gradation data, it is possible to insert the set number of blank data at the head of the line and move the recorded image to the right as a whole, and set the individual exposure position. Thus, the deviation of the LED array between the image forming units can be corrected.

The exposure position setting switch is preferably provided at a position where the setting can be changed from outside. For example, at the time of testing and adjusting the printer device, remove the maintenance cover and change the setting value of the exposure setting switch.
Make settings changeable. The exposure position setting switch of the exposure position control circuit may be a register whose setting can be changed from a host device or a controller of the printer device. For example, it is possible to control the exposure position only by operating the keys on the operation panel while performing the recording test by switching the printer device to the maintenance mode, which makes the control easier.

Further, by using the above-mentioned exposure position control, the amount of image data sent from the host device or the image memory can be reduced. Depending on the pattern of the image, the left side is often blank. In such a case, the number of blank dots on the left side is set in the exposure position setting register without sending a one-line image, and image data from which blank dots on the left side have been deleted is transferred as image data. Therefore, the image data to be transferred becomes compact, and the transfer time is shortened.

While the embodiments have been described with reference to the LED printer, the present invention is applicable to other linear light source arrays (for example, EL arrays, LD arrays, etc.) and shutter arrays (liquid crystal shutter arrays, PLZT shutter arrays, etc.). Can be used as is.

[0027]

As described above, according to the first aspect of the present invention, it is possible to simply and inexpensively correct the positional deviation between the formed images. In addition, even when a positional shift occurs after assembling the printer device, which is an image forming apparatus, it is possible to easily adjust the position.

Therefore, the man-hour and time required for assembly and adjustment can be reduced, which greatly contributes to the development of the printer. Further, according to the second aspect, in accordance with the arrangement of the image forming elements in the image forming section, the positional deviation between the images formed by the respective image forming sections is corrected in the arrangement direction of the image forming elements. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention;

FIG. 2 is an explanatory view of an LED array,

FIG. 3 is a timing chart of one embodiment;

FIG. 4 is a configuration diagram of another embodiment of the present invention;

FIG. 5 is an exposure position setting circuit according to another embodiment;

FIG. 6 is a timing chart of another embodiment,

FIG. 7 is a diagram illustrating the operation of a barrel shift register.

FIG. 8 is a configuration diagram of a high-speed LED color printer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Exposure position control circuit 12 ... Exposure position setting switch 20 ... Control timing generation circuit 40 ... LED array

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H04N 1/23 103 (72) Inventor Akihiko Ishii 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Hiroyuki Inoue 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Mikio Amaya 4-1-1, Kamiodanaka, Nakahara-ku, Nakasaki-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited

Claims (2)

[Claims] A storage unit configured to store a plurality of image data for forming a predetermined image so as to be handled for each image data; and a storage unit configured to store a plurality of image data for each image data in accordance with each image data stored in the storage unit. An image forming apparatus comprising: a plurality of image forming units that individually form images in a predetermined area; and forming the predetermined image by superimposing images formed for each image data, Each image is formed in the predetermined area by controlling the writing position of each image data stored in the storage unit based on positional deviation information between images formed in the predetermined area for each image data. An image forming apparatus comprising image forming position control means for adjusting a position to be formed. 2. An image forming device according to claim 1, wherein each of said plurality of image forming units has an image forming element array in which a plurality of image forming elements for forming a dot image in said predetermined area are arranged. A storage unit that stores information indicating whether or not to form a dot image corresponding to each image forming element of the image forming element row. A buffer configured to control a position for storing information indicating whether or not to form the dot image written to the line buffer in accordance with control of the image forming position control unit. The image forming apparatus according to claim 1, wherein: