Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
2000-04-18
2002-11-05
Hallacher, Craig A. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
C358S504000
Reexamination Certificate
active
06474768
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a test pattern printing method, an information processing apparatus and a printing apparatus, and more specifically to a test pattern printing method for printing a test pattern which is checked to detect a color deviation, the deviation being caused by variations in an output characteristic among print heads, and an information processing apparatus and a printing apparatus for performing printing of the test pattern.
2. Description of the Related Art
As devices for automated office work have come into wide use, opportunities for producing color images in offices have increased. Known output devices for outputting color images include printing apparatuses of various methods, such as an ink jet method, an electro-photographic method and a heat transfer method. These printing apparatuses have been able to output picture-like color images of relatively high quality in recent years.
Such printing apparatuses generally print color images using three colorants of chromatic colors, cyan (C), magenta (M) and yellow (Y), or four colorants with an additional achromatic color, black (K). The printed color images, however, may have a color deviation or color misrepresentation (e.g., produced color in the printed image differs from a desired one) due to an imbalance of output characteristics (reflection density or lightness, saturation, hue, etc.) among print heads for respective colors. In the ink jet system, for example, the print heads may have, among themselves, differences in an amount of heat produced by heaters (film thickness of the heater) for ejecting ink and differences in a size and shape of ink ejection orifices, causing variations in an amount of ejected ink. This in turn may result in the output characteristic imbalance among the print heads for individual colors, as described above. Not only do the print heads inherently have such differences, but it is also known that these differences are produced over time.
To cope with this problem, a personal computer functioning as a host computer for the printing apparatus, or the printing apparatus itself, may perform correction processing which involves detecting the color deviation due to the differences among respective print heads and, based on the result of detection, correcting the output characteristics of the print heads to have predetermined characteristics. Known correction processings include methods to be carried out in two ways, which are distinguished depending primarily on whether the detection of the color deviation is done by using an input device such as a scanner or by a human visual check. These two correction methods, as distinguished by the manner of detecting the color deviation, will be briefly explained below.
The method using the input device such as a scanner, for example, firstly prints a patch pattern by using the print heads of C, M, Y and K coloring materials that are the subjects of the correction, as disclosed in the official gazette of Japanese Patent No. 2661917. Then, the patch pattern is read by the scanner to detect a difference between a read value (representing an output characteristic of the head) and an expected value calculated from the print data for the patch pattern. Based on the detected difference, the color deviation is corrected. The patch pattern used in this method may be a solid pattern of each of C, M, Y, K colors or a patch pattern of each color having patches showing a gradation in density. The gradation patch pattern can also be used to detect an output characteristic with respect to a halftone, thus improving precision of detecting the color deviation. A method is also known as that combines the C, M, Y and K colors to form second- or third-color patch patterns and thereby improves the detection and correction accuracy.
On the other hand, the method using the visual check, unlike the method using the input device, cannot easily detect an absolute value with respect to the output characteristic for each color head. Hence, a detection method that uses a third-color patch pattern printed by mixing three colorants C, M, Y is mostly used. More specifically, a plurality of patches of almost gray color is printed. The plurality of patches include a patch as a central patch of the plurality of patches, which is expected to be printed at a predetermined ratio of three colorants (represented by print data of three colorants) so as to be a patch of an achromatic color when the patch is printed by using print heads with an average ink ejection amount or without any deviation of ink ejection amount, and other patches which are printed with their three-color ratios successively changed slightly. From the plurality of patches, a user visually chooses one patch closest to the achromatic color so as to detect the patch of the most appropriate output characteristic balance among the C, M, Y color print heads. Then, the correction data corresponding to the detected patch is used to correct the output characteristic of each print head. This method of detecting the color deviation takes advantage of a fact that a slight imbalance in the output characteristics among the C, M, Y color print heads causes influence of the color having relatively large output characteristic change to appear in the patch, resulting in the patch deviating from the achromatic color.
While the color deviation and the method of its detection have been described for the case of the print heads of the ink jet system, differences in the output characteristics of the color print heads may also occur with the printing apparatuses of the electrophotographic system and the heat transfer system due to causes peculiar to the principles of the respective printing systems. In these printing systems, also, the color deviation detection and correction are performed in a similar manner.
The conventional color deviation detection method described above, however, has the following drawbacks.
First, in a usual environment in which the printing apparatus is used, the method using an input device such as a scanner requires a condition that the user has an input device. Not all users have an input device available and thus the method using the scanner or other input devices is not realistic. If some input devices are made available, the correction process on a basis of the color deviation detection using such wide variation of input devices is often very difficult to be carried out.
The method based on the visual check, on the other hand, does not require any special input device and thus can be employed by any user to detect the color deviation. It is, however, not so easy to select a patch closest to an achromatic color from a plurality of patches with their C, M, Y color ratios progressively changed slightly.
For example, JIS (JIS E3305, JIS Z8721, JIS L0600, etc.) and various other organizations provide specifications concerning a color difference (&Dgr;E). In these specifications, a range of the color difference of 3.2-6.5 is defined as a “range that can be handled as the same color in terms of impression.” This suggests that visually picking up a patch closest to the achromatic color from patches in this range of color difference is difficult. It is also stated that the color difference in such a range may “cause a customer to complain about difference in color when selecting paint color,” suggesting that even in this range of color difference, if a wrong patch is selected, an image printed after being corrected by a correction value corresponding to the selected patch may fail to provide a desired color.
For this reason, an effort is being made to improve an accuracy of the visual check-based color deviation detection method.
FIG. 1
is a view schematically showing an example of a test pattern that enables an improvement of precision for detecting the color deviation. In
FIG. 1
, each frame represents a patch printed with a mixture of C, M and Y colors and with K. Four numbers in each of two areas in each patch represent multi-valued gradation data
Kanematsu Daigoro
Kato Masao
Kato Minako
Ono Mitsuhiro
Yano Kentaro
LandOfFree
Test pattern printing method, information processing... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Test pattern printing method, information processing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Test pattern printing method, information processing... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2989142