JP2004042473A - Printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify the arrangement of a printer by eliminating the need for continuous correction processing during print operation when an image is printed repetitively. <P>SOLUTION: Correspondence between the number of working nozzles in a print head and an image is determined such that a basic image being printed repetitively becomes an integer times of an image being formed by single scanning of a print head. From the correspondence between the nozzle and the image, correction of nonuniformity by an HS table is performed for the entire basic image using multilevel data. Subsequently, binarization of error diffusion is performed for the entire basic image. The image is printed repetitively by outputting that binary image data repetitively from a binary printer to a head having a predetermined number of nozzles sequentially. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a printer that employs a method of performing a print head unevenness correction process on image multi-value data corresponding to each nozzle in a nozzle unit, particularly when printing a repetitive image. The present invention relates to a method for performing a print head non-uniformity correction process and performing a print setting for printing image data after the binarization process by a printer so that the image data can be performed after the binarization process.
[0002]
[Prior art]
Conventionally, in order to correct the unevenness of the head, a predetermined density pattern is printed on all the nozzles used for printing, and this is read by an optical means such as a scanner, and the density unevenness state of the nozzles is grasped and optimally set in advance. A conversion table (hereinafter referred to as a head shading (HS) table) for calculating a density difference from a target value and correcting the difference is created in advance.
[0003]
At the time of printing image data, the multi-valued image data is corrected using the HS table and then subjected to binary processing to correct the unevenness of the head and output this from a fixed nozzle used in the print head. These processes are performed in each head printing.
[0004]
[Problems to be solved by the invention]
However, in the above-described conventional example, when a repetitive image is to be printed, as shown in FIG. In order to perform image printing with a nozzle different from the above, it is necessary to newly perform unevenness correction on image multi-value data corresponding to the nozzle using the HS table. Therefore, when printing an image repeatedly, it is necessary to read the image multi-value data from the memory each time during printing, and to perform binarization processing after correcting unevenness with the multi-value data in the conversion table. The device configuration by hardware means is necessary due to the need for speed, and a large load and cost are required for the system.
[0005]
An object of the present invention is to use a conventional HS table for unevenness correction using multi-valued data before printing in order to simplify the configuration of the apparatus for eliminating the waste of performing the continuous correction process during printing. Then, a binarization process is performed, and during printing, the system configuration is configured to output only the binary data after the process. Thus, simplification of the system configuration and cost reduction can be realized.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the vertical size of the basic image in the sub-scanning direction (media transport direction) is divided into integers or combined. At this time, at the time of division, one image vertical size is set to be equal to or less than the number of nozzles used by the print head.
[0007]
Next, a nozzle corresponding to the vertical size after division is selected from the head, and this is used for printing. Based on a conversion table used for correction processing, a portion corresponding to this nozzle is divided into image multi-valued data. The correction processing is performed, and then the binarization processing is performed on all the divided images. This correction and binarization are all completed only once, and there is no need to use multi-value data during printing.
[0008]
Next, when printing the binary image data, the print nozzle setting of the printer is changed. The number of nozzles and the feed amount of the print medium are changed so that the binarized image data can be printed in association with the nozzles selected when performing the above unevenness correction processing.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
(First embodiment)
First, it is assumed that the basic image described here handles multi-value data after color separation for each print color used in the printer. Since the color separation process is a problem of another technology, it will not be described here.
[0010]
An integer value for dividing or synthesizing the basic image is determined from the vertical size of the repeated basic image from the image information and the number of usable nozzles of the print head characteristics.
[0011]
If the image vertical size is smaller than the number of printable nozzles, the number of basic images that can be arranged for the number of nozzles is calculated, and the basic images of that integer are arranged and combined to form a new basic image. The number of nozzles corresponding to the vertical size is used in the print head.
[0012]
If the image vertical size is larger than the number of printable nozzles, the vertical size is divided by an integer to obtain an integer value that is smaller than the number of usable nozzles.
[0013]
The fraction at the time of division is allocated to each of the divided images and deleted or added so that all the divided images have the same size. The number of nozzles corresponding to the vertical size is used in the print head.
[0014]
The nozzle correspondence of the print head is determined for each raster of the divided image, and the correspondence of the conversion table for unevenness correction of the nozzles is also determined. The unevenness correction processing is performed using the corresponding conversion table.
[0015]
This is performed for all the divided images, and as a result, the unevenness correction is performed for the entire color of the basic image corresponding to the print head. The above processing is performed on all the multi-valued data of the print colors used by the printer, thereby completing the unevenness correction on all the basic images.
[0016]
Next, binarization processing is performed on the divided image as one basic image.
[0017]
Since the binarization processing is a problem of another technique, it will not be described in detail here, but it is assumed that the binarization processing using error diffusion is performed as an example.
[0018]
When printing the image data after the binarization processing for each ink color, read the print data from the memory and print to the head so that the print head prints in the unit of the divided image size. Set the data output.
[0019]
At this time, as a method of determining the nozzles to be used among all the nozzles of the print head, in order to disperse the degree of wear of each nozzle, each time printing is completed, the nozzle range selection from the upper side of the head and the nozzle range selection from the lower side are alternately performed. I will use it.
[0020]
(Second embodiment)
Another method for determining the image division size described in the first embodiment will be described.
[0021]
A case is considered in which a print head used in a printer has a configuration in which a print cycle is shifted by a half band using a head group of two rows in order to improve print density and connect an image seam between bands. See FIG. At this time, if the range of usable nozzles of the print head is “a”, the pitch between the head groups is “2.5 × a”, and the entire range of the nozzles at both ends is “3.5 × a”.
[0022]
When the image to be printed cannot be divided into integers by "a", the image is divided by "b", which is smaller than that. To perform half-band overlapping printing with each head group, the pitch between bands is 3.5. .. Must be 4.5, 5.5...
[0023]
Also, since the entire nozzle area is determined to be “3.5 × a”, (n + 1.5) × b ≦ 3.5 × a (n is an integer of 2 or more)
Condition must be satisfied.
[0024]
The non-printing nozzle area between the head groups is “1.5 × a”, from which 1.5 × a ≦ (n−0.5) × b (n is an integer of 2 or more)
Must also be satisfied.
[0025]
Thereby, the number b of nozzles for image division is determined.
[0026]
In actuality, the image size is not always divisible, so that it is determined by performing a correction of distributing and inserting or deleting each of the divided images so as to become a value close to the above “b” while changing the integer value to be divided.
[0027]
As to the actual print head, the nozzles to be used for the divided images determined as described above are arranged to be as uniform as possible in the head for each image, as in the first embodiment. If the number of divided images is actually determined by this method, the condition of “b” cannot be set continuously from the value of “a”.
[0028]
(Third embodiment)
In the second embodiment, the number of nozzles “b” is limited when dividing an image. However, by providing a mechanism that can change the physical pitch between the heads, the number of nozzles used in the print head can be set as desired. , And the above-mentioned limitation of the number of nozzles can be eliminated to maximize the use.
[0029]
【The invention's effect】
Since the binarization process is performed once before the printing process, it is easy to implement software, and there is no need to perform it during printing as in the conventional example. Therefore, it is simple to store hardware of image data and transfer it to the head. It can be configured.
[0030]
In addition, printing after binarization of repeated printing of an arbitrary image size becomes possible.
[0031]
Since only data to be used for printing is selected from the conversion table for unevenness correction, the conversion table can be created without any change.
[0032]
By making the feeding amount of the print medium constant, the feeding accuracy can be stabilized, and the image quality can be maintained.
[Brief description of the drawings]
FIG. 1 is a layout diagram of a basic image and an image printed by one scanning of a head when the present invention is implemented.
FIG. 2 is a layout diagram of a basic image and an image printed by one scan of a head in a conventional example.
FIG. 3 is a diagram showing a selected nozzle range in a head when the present invention is implemented.
FIG. 4 is a diagram showing a selected nozzle range in a head in a two-row printer according to a second embodiment when the present invention is implemented.
FIG. 5 is a diagram illustrating the adjustment of the distance between heads in a two-row printer according to the third embodiment when the present invention is implemented.
FIG. 6 is an image processing block diagram when the present invention is implemented.

Claims (3)

Means for determining the number of nozzles to be divided or combined with the basic image from the vertical size information of the basic image to be repeatedly printed and the number of printable nozzles of the print head characteristics, and the number of nozzles to be used;
At the time of the division, the fraction is allocated to each of the divided images and deleted or added to make all the divided images have the same vertical size, and the nozzle correspondence of the print head is determined for each of the divided images. Means for correcting data for unevenness correction using a conversion table for unevenness correction of
Means for converting the corrected image data into binary data, means for selecting from all nozzles of the print head of the used nozzle for each print, means for changing the transport amount of the print medium according to the number of used nozzles, and the basic image A printer having a function of outputting binarized data as a predetermined repetitive image and a function of printing the repetitive image by means for outputting the same to nozzles specified by a print head. In a printer in which a print head forms an image by overprinting in a two-row configuration,
2. A repeated image by using means for selecting and using the number of nozzles used so that the pitch between head rows is shifted by a half-period phase of the nozzle width used for printing in the determination of the vertical size of the divided image according to claim 1. Printer with the function to print out. In a printer in which a print head forms an image by overprinting in a two-row configuration,
A printer having a function of printing a repetitive image by using means for mechanically adjusting a distance between head rows so that a pitch between head rows is shifted by a half-period phase of a printing nozzle width.

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