JPH10838A - Print system, density correction method therefor and test pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a print system which is not influenced by an image reader by providing an information processing means for detecting a print pixel on a pattern corresponding to the position of a mark detected from image read-out results and obtaining a read-out image data corresponding to the print pixel for the print element. SOLUTION: Printing is performed by a printer 305 having a printing head comprising a plurality of printing elements and an image is brought close to a density correction pattern stored in a personal computer 304 before printing a mark. The print system comprises an information processing means for detecting that position based on the read-out results of an image reader 301 and detecting a print pixel on the pattern of a print element corresponding to the mark position based on the read-out results of the image reader 301, and an information processing means for acquiring a read-out image data corresponding to a detected print pixel for all print elements. Correspondence between the print element and the read-out pixel is determined based on the timing mark on a test pattern. According to the arrangement, the read-out resolution has no effect and the image reader can be replaced freely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to printing which prints a test pattern by a printing device, reads the printing result by an image reading device, and corrects the output of the printing device based on the reading result so that density unevenness does not occur. The present invention relates to a system, a density correction method thereof, and a test pattern used for density correction.

[0002]

2. Description of the Related Art A printing apparatus using a print head for discharging ink from an ink flow path (referred to as a printing element) forming a plurality of nozzles is known. The shape of the printing element of the print head of such a printing apparatus has minute variations, and density unevenness occurs in the printing result due to the influence and the variation in the ejection amount of the recording material, that is, the ink. A technique called head shading (hereinafter also referred to as HS) is known as a correction method for eliminating such density unevenness and making the density of a printing result uniform.

FIG. 1 shows a typical example of a printing system using this correction method. In FIG. 1, a document exposure system (image reading system) 101, an image processing unit 102, and an image forming unit 103 are formed in one apparatus. An original exposure system 101 reads an original image and outputs the read result to an image processing unit 102.
Hand over to In the image processing unit 102, H stored inside
Color correction and n-value conversion using n data (n =
2,3,4. . . . ). Of course, the correction using the HS method is also performed here. The HS data 105 is a conversion coefficient for directly converting the value of the read image signal into an output signal to be output to the print element of the print head 104, and is also used as a correction coefficient.

The corrected read data is sent to an image forming unit 103.
To be printed by the print head 104 described above.

In order to obtain HS data used for correction in such a printing system, a test pattern is printed by giving an output signal value of the same level to each printing element in advance, and the printing result is printed by a document exposure system 101. read. A part (pixel position) where the density distribution obtained as a result of the reading is not uniform is an abnormal part that needs to be corrected. The correction coefficient for obtaining the uniform density is determined from the values of the read image data at the abnormal and normal pixel positions. Many formulas for determining the correction coefficient have been proposed.

[0006]

However, in this type of conventional system, a scanner as an image reading apparatus corresponding to the image reading system 101 shown in FIG.
03 is externally connected to a personal computer corresponding to the image processing unit 102 with a printing device corresponding to the image processing unit 03, a storage device storing an image to be printed, and the like.
There is a possibility that a problem that the correction accuracy of S deteriorates. In particular, when the document exposure system 101 is an image reading apparatus such as a handy scanner that moves the document by manual driving, conveyance of the document becomes uneven. As a result, missing or redundant data occurs in the read test pattern, and the correspondence between the print pixel position of each print element of the print head and the read pixel position corresponding to the print pixel position is lost. Problems arise.

[0007] The change in the correspondence between the print pixel position and the read pixel position as described above means that the print element to be corrected is changed to a print element that does not need to be corrected, and as a result, the image quality of the print deteriorates. Occurs.

Accordingly, an object of the present invention is to provide a printing system which is not affected by an image reading device when creating density correction data using a read image of a test pattern, a density correction method thereof, and a test pattern. It is in.

[0009]

In order to achieve the above object, according to the present invention, a pattern for density correction is printed by a printing apparatus having a print head in which a plurality of printing elements are arranged, In a printing system for reading the pattern of the print result by an image reading device and performing density correction for each print element on image data to be printed in an information processing device based on image data of the read pattern, A plurality of marks, a print control unit for causing the printing device to print the plurality of marks to be printed by the plurality of printing elements in close proximity to the pattern, and the position of the plurality of printed marks to the image reading device. Image analysis means for detecting from the read result of the above, and said printing element corresponding to the detected positions of the plurality of marks A first information processing means for detecting the print pixels on the turn from the read result of the image reading apparatus, a second of acquiring read image data for all said plurality of printing elements corresponding to print pixel the detected
The information processing means is provided with the information processing means.

According to a second aspect of the present invention, in the printing system according to the first aspect, the plurality of marks are printed by a printing element at regular intervals.

According to a third aspect of the present invention, in the printing system according to the second aspect, the plurality of marks are printed in a plurality of stages.

According to a fourth aspect of the present invention, in the printing system according to the third aspect, the print head according to the first aspect is prepared for a plurality of colors, and prints the mark in a different color for each stage. Features.

According to a fifth aspect of the present invention, a plurality of marks according to the first aspect are printed so as to be symmetric about the pattern.

According to a sixth aspect of the present invention, a pattern for density correction is printed by a printing apparatus having a print head in which a plurality of printing elements are arranged, and the pattern of the printing result is read by an image reading apparatus. In a density correction method of a printing system for performing a density correction for each printing element in image data to be printed in an information processing apparatus based on image data of a pattern, a plurality of marks for position detection, wherein the plurality of printing elements A plurality of marks to be printed are printed by the printing device in proximity to the pattern, the positions of the plurality of printed marks are detected from the reading result of the image reading device, and the positions of the detected plurality of marks are detected. The print pixels on the pattern of the print element corresponding to the image are detected from the read result of the image reading device. And, and acquires the read image data corresponding to print pixels corresponding detected for all said plurality of printing elements.

According to a seventh aspect of the present invention, a pattern for density correction is printed as a test pattern by a printing apparatus having a print head in which a plurality of printing elements are arranged, and the pattern of the printing result is read by an image reading apparatus. Based on the image data of the read pattern, in a test pattern for performing density correction for each print element in the image data to be printed in the information processing apparatus, a plurality of marks for position detection, A plurality of marks to be printed are arranged close to the pattern.

According to an eighth aspect of the present invention, in the test pattern according to the seventh aspect, the plurality of marks are printed by printing elements at regular intervals.

According to a ninth aspect of the present invention, in the test pattern according to the eighth aspect, the plurality of marks are printed in a plurality of stages.

According to a tenth aspect of the present invention, in the test pattern of the ninth aspect, the print head of the seventh aspect is prepared for a plurality of colors, and prints the mark in a different color for each stage. Features.

An eleventh aspect of the present invention is characterized in that the plurality of marks according to the seventh aspect are printed symmetrically with respect to the pattern.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 shows a system configuration of a printing system to which the present invention is applied. 2, a printer 201, a scanner 203, and a storage device 204 are connected to a personal computer 202. FIG. 3 shows the internal configuration of the personal computer 202. FIG.
, The CPU 310 is the personal computer 30
In addition to performing the system control of No. 4, head shading correction according to the present invention is performed. The head shading processing of this embodiment differs from the conventional example in the following points. First, an image of a test pattern (described later) as shown in FIG. 5 is built in the personal computer 304, and this test pattern is printed when HS correction data is created. Second, a timing mark described in the test pattern is detected from the read image, and a print element is associated with a read pixel using the timing mark.

The system memory 311 has a ROM and RA
M, and temporarily stores data used for the operation of the CPU 310. The test pattern image read by the scanner 301 is also stored in the system memory 311. An input / output interface (I / O) 312 is a SCSI interface connected to the scanner 301 or a printer 3
It has a serial interface connected to the CPU 310 and performs data transfer between an externally connected device and the CPU 310.

The hard disk storage device 313 stores the control procedure of FIG. 6 for creating HS correction data in the form of a program language executable by the CPU 310. Further, an image for printing the test pattern of FIG. 5 is stored. The HD 313 also stores a control program (also called a driver) for controlling the scanner 301, the printer 305, and the storage device 302. A keyboard (KB) 314 inputs an operation instruction to the CPU 310 and various data. A pointing device called a mouse is connected to the keyboard 314.
An operation instruction can also be given by specifying a position on the display screen of T315 with a mouse.

The CRT 315 displays an image to be printed under the control of word processing software, image processing software, or drawing software. A storage device (a magneto-optical storage device, a floppy disk storage device, or the like) 302 is connected to such a personal computer 304, and an image to be printed is read from the storage device 302 to the personal computer 302. As the printer 305, a color barcode printer is used.

FIG. 4 shows a schematic structure of a recording unit of the printer 305.
Shown in The color barcode printer is a head 40 that discharges black, cyan, magenta, and yellow inks.
1, 402, 403, and 404.

The structures of the heads 401 to 404 are common, and the configuration of the nozzle arrangement is shown in FIG. One head in a row
360 ink ejection nozzles are arranged, and 1344 of them are used for printing a drawing area. These nozzles are divided into 11 blocks,
Drive control is performed in block units.

A test pattern used in this embodiment will be described with reference to FIG. Reference numerals 604 to 607 are timing marks according to the present invention. The first-stage timing mark 604 is a linear image printed by the first nozzle 602 at the left end of the drawing area of the head 601. The second timing mark 604 on the first stage is a linear image printed on the fifth nozzle 602.
Hereinafter, the ninth nozzle 602 and the thirteenth nozzle 60
2. . . Thus, an image of the timing mark 604 to be printed in the drawing area by the nozzle 602 at a constant interval is prepared. The second-stage timing marks are the second nozzle 602, the sixth nozzle 602, the tenth nozzle 602. . . , The image of the timing mark 605 is printed.

Similarly, the timing mark 606 is formed by a nozzle group at a fixed interval starting from the third nozzle 602 from the left end, and the timing mark 608 is formed by a nozzle group at a fixed interval starting from the fourth nozzle 602 from the left end. This is the image to be printed. Such timing marks are provided symmetrically with respect to the head correction pattern 608. By printing the timing marks with the nozzles 602 at regular intervals in this manner, blank portions are generated between the timing marks, and it becomes easy to detect the timing marks in the read image, as described later. The timing mark has a nozzle 6 in the drawing area on one side.
Print using all 02. In addition, a pair of timing mark groups are prepared symmetrically with respect to the head correction pattern.

As the head correction pattern 608, a pattern similar to the conventional one can be used. In this example, there are four color areas, and a binarization pattern is used in which the nozzles 602 form an image at a uniform density of 50% of the maximum density using each of the print heads 401 to 404. In the simplest example, four rectangular areas can be filled with four colors.

Using such a test pattern, the HS
A process for creating data (conversion coefficients) will be described with reference to FIG.

When the execution of the processing procedure shown in FIG. 6 is instructed from the keyboard 314, the CPU 310 reads the test pattern image from the HD 313, performs print control, and causes the printer 305 to print. This printing control is realized by a printing control program called a printer driver (step S502). At this time, the CPU 310 operates as the print control unit of the present invention. After the print result is set on the scanner 301 and the CPU 310 knows that the information is input from the keyboard 314, the CPU 310
Controls the scanner 301 by the scanner driver to read the test pattern image. The read result is stored in the system memory 311 via the I / O 312 (step S502).

The CPU 310 performs image analysis on the read result to detect a timing mark. FIG.
Are read in the main scanning direction to obtain image data (luminance value) for each pixel. The reading in the main scanning direction is performed a plurality of times (n times) along the sub-scanning direction. When n pieces of image data having the same pixel position in the main scanning direction are summed, the distribution of the total value (luminance value) along the main scanning direction, that is, the nozzle row direction is as shown by reference numerals 701 to 704 in FIG. Become. Timing marks denoted by reference numerals 604 to 607 correspond to the luminance distributions 701 to 704, respectively. Therefore, the CPU 310 detects the coordinate value having the minimum value of the luminance distribution, acquires the image data of the head correction pattern corresponding to the coordinate value, and calculates the average value.

More specifically, the pixel position in the read image of the timing mark printed by the first nozzle is X1, Y1 as shown in FIG. 7 (where the main scanning direction is the X axis, When the direction is obtained as Y axis),
The image data of the X1 coordinate in the image data of the head correction pattern is extracted, and the average is obtained. Such an average value is called a raster average. This raster average value is written to the buffer area in the system memory 311 as the density value of the pixel printed by the first nozzle. Hereinafter, the above processing is performed for the number of nozzles in the drawing area (134 in this example).
When this is repeated for four colors, the image data printed by all the nozzles in the drawing area for a certain color is written to the buffer area 705. An HS data in which the density value becomes non-uniform is found, and HS data is created so that the density value becomes uniform after the density correction. It goes without saying that the position of this buffer corresponds to the position of the nozzle. Since a well-known process can be used for the HS data creation process itself, a detailed description will not be required.

The processing described above is an example in which only one side of the timing mark is used. When the timing marks on both sides are used, for example, the read coordinate position X of the first timing mark (two existing with the head correction pattern interposed) printed by the first nozzle is used.
1, X1 'is detected, and the raster average value of the head correction pattern having the coordinate value of (X1 + X1') / 2 is obtained. By performing the above process for four colors, color HS data is created (step S504). The created HS data is stored and stored in the HD 313, and is used for density correction at the time of subsequent printing.

In this embodiment, since the above-described timing marks are printed in a plurality of stages, blank portions are generated between the timing marks, and the position of the timing marks can be easily detected.
In addition, since the color is changed for each stage, it is easy to recognize the break between the stages.

The following example can be carried out in addition to this embodiment.

1) In the above embodiment, the line type print head in which the printing elements are arranged for one line in the main scanning direction has been described. However, the printing head in which a plurality of printing elements are arranged in the sub scanning direction is used in the main scanning direction. The present invention can also be applied to a printer that is transported to a printer. In this case, the description direction of the straight line of the timing mark of the test pattern is the main scanning direction, that is, the test pattern of FIG. 5 is rotated by 90 degrees.

2) In the above-described embodiment, four stages of timing marks are prepared on one side, and the timing marks are color-coded for each stage. A configuration that changes the shape may be used.

3) In the above embodiment, a color printer has been described as an example. However, the present invention can also be applied to a printer that performs black and white gray gradation printing.

4) The print head to which the present invention is applied is not limited to the ink ejection printing element, but may be a heat transfer type printing element, and is not limited to the form of the printing element, but is most effective for the ink ejection printing element. It is a target. In this case, the density correction may be performed by the driving voltage of the printing element, and a γ correction table is created for each printing element.

[0040]

As described above, the first, sixth and seventh aspects of the present invention are described below.
According to the invention, the correspondence between the read pixel position of the density correction pattern and the printing element printed at the pixel position is detected in the mark. Even if the scanned document is misaligned,
Since the marks are also relatively displaced together with the density correction pattern, the above-mentioned correspondence does not change. Further, even if the reading resolution of the image reading device is changed, the relative position between the mark and the density correction pattern in the reading result does not change, so that the reading resolution is not affected. For this reason, the image reading device can be freely exchanged for another model.

According to the second and eighth aspects of the present invention, a blank portion is formed between the marks, and the detection of the mark in the read image is facilitated.

According to the third and ninth aspects of the present invention, by printing the marks in a plurality of stages, the blank distance between the marks can be increased, and the marks of a large number of printing elements can be printed.

According to the fourth and tenth aspects of the present invention, it is easy to distinguish steps by different colors.

According to the fifth and eleventh aspects of the present invention, two marks are formed by the same printing element and are opposed to each other with the density editing pattern at the center. The printing position of the printing element can be specified from the two marks.

[Brief description of the drawings]

FIG. 1 is a functional block diagram illustrating a system configuration of a conventional printing system.

FIG. 2 is a functional configuration diagram illustrating a system configuration according to an embodiment of the present invention.

FIG. 3 is a block diagram illustrating a system configuration of a personal computer according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating a structure of a recording unit of the printing apparatus.

FIG. 5 is a configuration diagram illustrating a nozzle arrangement and a test pattern of a print head.

FIG. 6 is a flowchart illustrating a processing procedure according to the embodiment of the present invention.

FIG. 7 is an explanatory diagram illustrating a positional relationship between timing mark positions and correction data.

[Explanation of symbols]

 Reference Signs List 101 Exposure system 102 Image processing unit 105 HS data 103 Image forming unit 104 Print head 201, 305 Printing device (printer) 202, 304 Personal computer 203, 301 Image reading device (scanner) 204, 302 Storage device

Claims (11)

[Claims] A printing apparatus having a print head having a plurality of printing elements arranged thereon prints a pattern for density correction, reads the pattern of the printing result by an image reading device, and converts the pattern into image data of the read pattern. A printing system that performs density correction for each printing element on image data to be printed in an information processing apparatus, wherein a plurality of marks for position detection, the plurality of marks to be printed by the plurality of printing elements are formed by the pattern. Print control means for causing the printing apparatus to print in close proximity to the apparatus, image analysis means for detecting the positions of the plurality of printed marks from the reading result of the image reading apparatus, and The printing pixels on the pattern of the corresponding printing element are read from the reading result of the image reading device. Wherein the information processing means comprises: first information processing means for detecting; and second information processing means for acquiring read image data corresponding to the detected print pixels for all of the plurality of printing elements. system. 2. The printing system according to claim 1, wherein the plurality of marks are printed by printing elements at regular intervals. 3. The printing system according to claim 2, wherein the plurality of marks are printed in a plurality of stages. 4. The printing system according to claim 3, wherein the print head according to claim 1 is prepared for a plurality of colors, and prints the mark in a different color for each stage. . 5. The printing system according to claim 1, wherein a plurality of marks are printed so as to be symmetric about the pattern. 6. A pattern for density correction is printed by a printing apparatus having a print head in which a plurality of printing elements are arranged, and the pattern of the printing result is read by an image reading apparatus, and the image data of the read pattern is added to the pattern. In a density correction method of a printing system for performing density correction for each print element for image data to be printed in an information processing apparatus, a plurality of marks for position detection, the plurality of marks being printed by the plurality of print elements. Causing the printing device to print the mark in close proximity to the pattern; detecting the positions of the plurality of printed marks from the reading result of the image reading device; and printing elements corresponding to the detected positions of the plurality of marks. Detecting the printing pixels on the pattern from among the reading results of the image reading device; Density correcting method of a printing system, characterized in that the read image data to obtain for the all of the plurality of printing elements corresponding to the printing pixels. 7. A printing apparatus having a print head in which a plurality of printing elements are arranged, a pattern for density correction is printed as a test pattern, and the pattern of the printed result is read by an image reading apparatus, and the read pattern is read. In a test pattern for performing density correction for each printing element in image data to be printed in an information processing apparatus based on image data, a plurality of marks for position detection, a plurality of marks to be printed by the plurality of printing elements. A test pattern, wherein the test pattern is arranged close to the pattern. 8. The test pattern according to claim 7, wherein the plurality of marks are printed by printing elements at regular intervals. 9. The test pattern according to claim 8, wherein the plurality of marks are printed in a plurality of stages. 10. The test pattern according to claim 9, wherein the print head according to claim 7 is prepared for a plurality of colors, and prints the mark in a different color for each stage. . 11. A test pattern, wherein the plurality of marks according to claim 7 are printed symmetrically about the pattern.