Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
2000-04-18
2003-01-14
Hallacher, Craig (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
C358S504000
Reexamination Certificate
active
06505909
ABSTRACT:
This application is based on patent application Ser. No. 11-111495 (1999) filed Apr. 19, 1999 in Japan, the content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printing system which conducts printing operation by using coloring materials of a plurality of colors, and more specifically to a printing system equipped with a calibration function, a printing system which can form test patterns in order to detect printing characteristics such as output density balance of each color, an information processing apparatus, and a printing apparatus.
2. Description of Related Art
Multi-media is making a rapid progress nowadays along with the propagation of personal computers and OA (office automation) equipment as well as the development of communication technology. Under such circumstance, there is a tendency that color images are increasingly demanded. As output devices for color images, various printing systems have been developed. For example, there are printers of the ink jet system, the electro-photographic system, and the heat transfer system.
In the case of current printing devices where photograph-like color image output is frequently produced, color images generally use three coloring materials (colorants) of chromatic colors, namely, cyan (C), magenta (M), and yellow (Y) or four coloring materials that include the three chromatic color materials and black (K). However, because of the balance of the output characteristics (reflection density or lightness, i.e. brightness of color or darkness of color, saturation, hue, etc.) among difference printing heads that print each coloring material, it does not necessarily follow that they are suitable for all apparatuses.
For instance, in an ink jet printing device, among printing heads, there are variations in an amount of heat (film thickness) generated by heaters to eject ink, and variations in size (diameter) of ink ejection nozzles, causing differences in the amount of ejected ink among the individual printing heads. There are some cases in which such individual differences give rise to a color deviation (a density deviation). In such cases, a desired image quality cannot be obtained. Thus, in order to compensate for such color deviations, the printing apparatus is equipped with various calibration functions such as &ggr; correction as well as various other color deviation correction means.
In the calibration, a detection pattern is actually printed on predetermined printing media. Data showing color deviation as obtained by detection from such a printing result is used as data to compensate for the color deviation.
As a color deviation detection method based on individual differences among the devices, two methods are actually used. In one method, the detection pattern is detected by using a detection instrument such as a scanner. In the other method, the detection is conducted visually by eye.
Now, the detection method of each of the above-mentioned color deviations will be outlined below.
In the method using an input instrument such as a scanner, for instance, as used in Japanese Patent No. 2661917, a detection pattern is printed for each coloring material (colorant) consisting of C, M, Y, and K, and then, each pattern is read out with a scanner. A deviation between a value thus read out and an expected output value of each detection pattern Is detected. Based on such deviations, the method of correcting the color with &ggr; value is disclosed.
At this time, there is one method in which as a detection pattern to detect the color deviation, a gradation pattern of each elemental color is printed along with a solid pattern of C, M, Y, and K; and not only the color deviation of a single gradation but also output characteristics of intermediate gradation is also detected, thereby improving the accuracy of color deviation. There is another method in which the detection correction accuracy is improved by printing patch patterns of secondary and tertiary colors which combine C, M. Y, and K, individually.
On the other hand, in the method in which visual detection is used, the following method is employed.
Since it is difficult to detect absolute values of the output characteristics of the respective elemental colorants, principally 3 coloring materials of C, M, and Y are mixed. A detection pattern of the tertiary color of this mixture is printed. Color deviations are detected therefrom. More specifically, in the method, a printing pattern formed by using a tertiary color obtained by mixing the coloring materials of C, M, and Y at a ratio where achromatic color is expected when using printing heads each having an average discharge amount printed at a center, a plurality of test pattens having substantially gray color obtained by mixing the coloring materials with a ratio slightly changed are printed around the printing pattern, and then a test pattern which is the closest to the central achromatic color among the test patterns is visually selected. In this way, the output characteristics of each coloring materials of C, M and Y are detected. In other words, this detection method utilizes the fact that the gray color patterns are no longer an achromatic color when an effect of the color material having large output characteristics is caused by a slight deviation in balance of the output characteristics of C, M and Y. If this detection method is used, even in the case of visual detection, color deviation can be detected easily.
With respect to cases in which color deviation detection is conducted by this visual detection method, one example of the detection pattern will be explained using FIG.
11
.
In
FIG. 11
, the detection pattern P shown therein consists of a set of patches (pattern set) composed of a pair of top and bottom frames in contact with each other, with sets more than one (in this case the number is 5) being aligned sideways to thereby constitute P (1, 1) to P (5, 5). In the figure, the four numbers shown in the upper frame and the lower frame inside of each patch represent multi-value gradation levels of C, M, Y, and X from the top. In addition, said upper frames are patch patterns of process black (PCBk) which is made by mixing coloring materials having chromatic colors C, M and Y, and the patch pattern of the lower side is composed of a coloring material of achromatic color, black (K) only. The PCBk of the upper side has Y fixed at a level of 128. Gradation values for C become larger as patches are arranged closer to the right side (i.e., the density becomes higher), and gradation values for M become larger as patches are arranged at the lower side.
As described above, since the patch pattern of PCBk and the patch pattern of Bk are laid out in the above detection pattern, it becomes possible to improve the detection accuracy based on visual detection to a considerable degree. This is a detection method that utilizes visual characteristics of a human being such that even slight color deviations can be detected in the case a plurality of objects are placed adjacent to each other. Hereinafter, this comparison method shall be referred to as the adjacency comparison method.
According to this adjacency comparison method, even if the color difference is at a sufficiently low level of 0.8 to 1.6, it is known that the color difference can be recognized. As a result, in comparison with vaguely selecting a patch that is closest to an achromatic color from among a plurality of PCBk patches, the detection accuracy can be improved significantly. For instance, even in case the color difference is at a sufficiently low level such as 0.8 to 1.6, the detector can recognize the difference reliably. By inputting correction data obtained on the basis of a gradation value of each color material that forms a detection pattern that is closest to black K, calibration is conducted, and a suitable image having no color deviation is obtained.
In the case of the printing apparatus in which the color deviation of the individual apparatus is compensated by said ca
Kanematsu Daigoro
Kato Masao
Kato Minako
Ono Mitsuhiro
Yano Kentaro
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Hallacher Craig
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