Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-03-09
2001-10-09
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S040000, C347S043000
Reexamination Certificate
active
06299282
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording apparatus that records images, such as characters, figures, and patterns, on a recording medium.
2. Related Background Art
There has been known conventionally the so-called serial recording apparatus that records on the surface of a recording medium by enabling the carriage that mounts a recording head thereon to travel in the direction orthogonal to the carrying direction of the recording medium. With the serial recording apparatus thus arranged, images are recorded on a recording medium by repeating the recording operations to carry the recording medium and to move the carriage alternately. In general, the carriage travels along the carriage shaft, and a motor is used as the driving power therefor. The driving power of the motor is transmitted to the carriage through a timing belt which is tensioned around the pulley of the motor and partly fixed to the carriage.
In recent years, there have been more demands to the higher image formation, and the materialization of high image quality as well. To meet such demands, a structure is adopted so that images are recorded by use of plural lines of pixel arrays each formed by plural pixels. Then, for example, a color recording apparatus or the like has been proposed with a carriage which is provided with the plural recording heads each using yellow, magenta, cyan, and black, respectively, in a state where these heads are arranged side by side in the traveling direction of the carriage, thus performing color printing by overlaying each of the colors as required.
Here, when the motor is driven as the driving source of carriage movement as described above, the traveling speed of the carriage is subjected to the changes of its speed due to the run-out (eccentricity) of the driving pulley, for example. The changes of carriage speed that may take place in such a manner tend to bring about the unevenness of recording images eventually. For the color recording apparatus or the like which performs the color recording by overlaying each of the colors with the carriage having the four-color heads arranged on it side by side in the traveling direction of the carriage, such recording unevenness is allowed to appear as the deviation of each color in a recording image, and results in the degradation of image quality ultimately.
Of the serial recording apparatuses described above, the ink jet recording apparatus which performs the image recording by discharging ink droplets from the recording heads, in particular, finds it necessary to make the distance between each of the plural recording heads substantially equal to the moving amount of the driving pulley per rotation or integral times such moving amount in order to reduce the degradation of image quality due to the changes of carriage speed. A structure of the kind has been disclosed in the specification of Japanese Patent Application Laid-Open No. 03-246059 and the specification of Japanese Patent Application Laid-Open No. 05-155092, for example. Also, in the specification of Japanese Patent Application Laid-Open No. 06-91896 and the specification of Japanese Patent Application Laid-Open No. 09-248922, it has been disclosed that the timing of ink discharges is made changeable for each of the recording heads in order to correct the changes of carriage speed due to the pulley run-out.
The problems described above are caused by the changes of the carriage speed. Here, the cycle of the speed changes is relatively large, such as almost equivalent to one cycle of the pulley. However, the cycle of the speed changes is relatively small as the component of acceleration. For the conventional ink jet recording apparatus, the unevenness of recorded images and the color deviation may take place due to the positional deviation of the recording heads caused by such changes of the carriage speed at the time of discharging ink. For example, therefore, it may be possible to solve the problems by effectuating the discharge timing appropriately by use of an encoder or the like provided within the traveling range of the carriage.
However, among the factors that may cause the speed changes of the carriage, there are, besides the one described above, those having a relatively small cycle, but relatively large component of acceleration, which are caused by the vibrations due to the gap between the tooth of the timing belt, the torque ripple of the motor, or due to the vibration frequency inherent in the vibrating system of the driving systems as a whole.
The image unevenness and color deviation that may be caused by those factors described above are smaller than those caused by the eccentricity of the pulley or the like. However, the aforesaid vibrations or the like caused by the minute vibrations due to the “play” between the carriage having the recording heads mounted thereon, and the carriage shaft, which may also bring about the image unevenness and color deviation, cannot be prevented by the provision of the structure whereby to make the timing of ink discharges appropriate by use of the encoder or the like.
SUMMARY OF THE INVENTION
With a view to solving the problems discussed above, the present invention is designed. It is an object of the invention to provide a recording apparatus capable of recording images in a high quality by suppressing the image unevenness and color deviations caused by the minute vibrations of the carriage driving system.
It is another object of the invention to provide a recording apparatus capable of suppressing the generation of minute vibrations of the carriage by enabling the phase of positional deviations of each of the pixel arrays to be in agreement with each other as to the recording position on a recording medium, thus preventing the image unevenness and color deviations from being created when overlaying each of the recorded images formed by each of the pixel arrays.
It is still another object of the invention to provide a recording apparatus having a carriage capable of traveling with recording means mounted thereon to record images on a recording medium, which comprises carriage traveling means for enabling the carriage to travel at a traveling speed v in a constant speed condition: the carriage traveling means drives the carriage by a carriage driving system having an inherent vibration frequency f; and a plurality of pixel arrays formed by plural pixels for each of recording means arranged in parallel with each other: each of the pixel arrays themselves adjacent to each other is arranged for the pixel arrays to be at interval of the integral times of the v/f.
It is a further object of the invention to provide a recording apparatus having a carriage capable of traveling with recording means mounted thereon for recording images on a recording medium, which comprises a timing belt for transmitting to said carriage the driving power of a driving source for the carriage to travel: the timing belt is provided with a plurality of tooth portions for transmitting the driving power; and a plurality of pixel arrays formed by plural pixels for each of recording means arranged in parallel with each other: each of the said pixel arrays themselves adjacent to each other is arranged for the pixel arrays to be at interval of the integral times of the tooth portions of the timing belt.
It is still a further object of the invention to provide a recording apparatus having a carriage capable of traveling with recording means mounted thereon for recording images on a recording medium, which comprises a driving source for said carriage to travel: the driving source is provided with torque ripple; and a plurality of pixel arrays formed by plural pixels for each of recording means arranged in parallel with each other: each of said pixel arrays themselves adjacent to each other is arranged for said pixel arrays to be at interval of the integral times of the torque ripple of the driving source.
Other objectives and advantages besides those discussed above will be apparent to those skilled in the art fr
Barlow John
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Hallacher Craig A.
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