Incremental printing of symbolic information – Thermal marking apparatus or processes – Gradational recording
Reexamination Certificate
1999-09-08
2001-04-03
Tran, Huan (Department: 2861)
Incremental printing of symbolic information
Thermal marking apparatus or processes
Gradational recording
C347S180000, C347S181000, C347S182000, C347S211000
Reexamination Certificate
active
06211893
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a multi-gradation recording method using a printer of the type wherein each one pixel is formed by using each one recording element and the optical density of one pixel formed is represented by the magnitude of the area of the pixel, e.g. printers of various recording systems such as xerography, thermal transfer recording and ink jet recording.
In various recording systems such as xerography, thermal transfer recording and ink jet recording, it is difficult to perform multi-gradation recording according to a density gradation method because it is hard to control the density of pixels to be recorded by toner or ink by itself. Therefore, in such recording systems, a variety of attempts have been made to perform satisfactory multi-gradation recording.
With respect to a method of representing tones, especially intermediate tones by an area gradation method of changing the size of one dot, for instance, in the thermal transfer system, a method of arranging dots to be transferred in the so called zigzag pattern or checkered flag pattern is disclosed in JP, B, 6-59739. It is possible to reproduce satisfactory intermediate tones by the use of this recording method. However, in performing recording in high density region, a large amount of recording energy is required because it is necessary to transfer an ink dot having a larger size than that of a heating resistor of a thermal head. Further, the recording method has the drawback that in performing recording in low density region or high density region, the resultant image has rough appearance and the profile or line of the image is notched due to large clearance between the dots.
Another method of arranging dots to be transferred every other one-dot line, i.e. in a stripe pattern in reproducing intermediate tones is disclosed in JP, B, 7-46828. This method copes with recording in high density region by arranging dots in clearance between the stripes, but the rough appearance or notchy line in low density region is not taken into consideration.
In view of the foregoing, it is an object of the present invention to provide a multi-gradation recording method wherein the recording energy in high density region can be reduced, and the rough appearance in low density region or high density region and notchy appearance in profile or line of the image can be reduced while maintaining the same level of reproduction of intermediate tones as obtained by the conventional recording method using the zigzag pattern or the stripe pattern.
This and other objects of the present invention will become apparent from the description hereinafter.
SUMMARY OF THE INVENTION
The present invention provides (1) a multi-gradation recording method comprising:
using a printer of the type wherein each one pixel is formed by using each one recording element and the optical density of the pixel formed is represented by the magnitude of the area of the pixel,
dividing input data into two or more groups with respect to the data corresponding to pixels to be arranged in principal scanning direction,
correcting the data of each group on the basis of the corresponding &ggr; correction data, the &ggr; correction data for the respective groups being different from each other, and
performing recording on the basis of the corrected data wherein the pixels of all the groups are recorded at the same time in the same scanning operation in principal scanning direction.
The present invention further provides (2) the multi-gradation recording method of the above (1), wherein the input data is divided into a group of data corresponding to even-numbered pixels and a group of data corresponding to odd-numbered pixels in principal scanning direction.
The present invention furthermore provides (3) the multi-gradation recording method of the above (2), wherein the recording control corresponding to the group of even-numbered pixels and the recording control corresponding to odd-numbered pixels in principal scanning direction are changed alternately every other unit of secondary scanning or every appropriate number of units of secondary scanning.
The present invention also provides (4) a multi-gradation recording method comprising:
using a printer of the type wherein each one pixel is formed by using each one recording element and the optical density of the pixel formed is represented by the magnitude of the area of the pixel,
dividing input data into two or more groups with respect to the data corresponding to lines in secondary scanning direction,
correcting the data of each group on the basis of the corresponding &ggr; correction data, the &ggr; correction data for the respective groups being different from each other, and
performing recording on the basis of the corrected data.
The present invention further provides (5) the multi-gradation recording method of the above (4), wherein the input data is divided into a group of data corresponding to even-numbered lines and a group of data corresponding to odd-numbered lines in secondary scanning direction.
REFERENCES:
patent: 4675697 (1987-06-01), Sasaki et al.
patent: 4691211 (1987-09-01), Brownstein
patent: 4779102 (1988-10-01), Sasaki
patent: 4873535 (1989-10-01), Sasaki
patent: 4952085 (1990-08-01), Rein
patent: 5112149 (1992-05-01), Suenaga
Mori Satoshi
Yoshida Naoki
Fish & Neave
Fujicopian Co. Ltd.
Tran Huan
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