Incremental printing of symbolic information – Thermal marking apparatus or processes
Reexamination Certificate
1998-03-19
2001-03-06
Le, N. (Department: 2861)
Incremental printing of symbolic information
Thermal marking apparatus or processes
C347S009000
Reexamination Certificate
active
06198493
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording apparatus such as an ink jet recording apparatus and a thermal transfer recording apparatus.
2. Description of Related Art
With conventional recording apparatus such as ink jet recording apparatus and thermal transfer recording apparatus, the diameters of a plurality of lots printed on a print medium are varied to provide gradation. For this purpose, the recording head is driven for different time lengths in accordance with print data to control sizes of ink drops ejected from the orifices or amounts of ink thermally transferred to the print medium.
For conventional ink jet recording apparatus, controlling the ink drop size alone cannot provide an adequate size ratio of a minimum dot to a maximum dot to provide a desired gradation. In order to overcome this drawback, acoustic vibration of the ink channel is utilized to eject more than one ink drop successively, which merge into a single large drop before landing on the print medium.
The aforementioned conventional recording apparatus use fixed drive frequencies. If the recording head is driven a longer time for a larger ink drop or driven more than one time for improved gradation, the overall printing time is longer. This leads to a lower printing speed.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a recording apparatus which is driven at a high drive frequency to obtain an increased printing speed.
A recording apparatus comprises a lot data generator that generates dot data from print data and outputs the dot data. A drive frequency setting section sets a drive frequency in accordance with print data. A drive signal generator receives the drive frequency setting signal and generates a drive signal having drive times and timings for driving a recording head. The drive times change in accordance with the dot data and the timings are in timed relation with the drive frequency. The recording head is driven by the drive signal to form a plurality of dots on a print, medium. The dots have different diameters according to the drive time.
The recording apparatus further comprising a mode selector which selects a printing mode in accordance with a specified resolution of the print data. The drive frequency setting section sets the drive frequency in accordance with the selected printing mode.
The recording apparatus still includes an operation circuit which determines a total drive time for which the recording head is driven to form dots corresponding to the dot data. The operation circuit determines the total drive time on a line-by-line basis and the drive frequency setting section sets the drive frequency on a line-by-line basis.
The drive signal generator may give a delay to the timing, so that the ink drops land on predetermined locations on the print medium
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even when the drive frequency varies from line to line.
The recording head includes a first channel holding a more frequently used ink therein and a second channel holding a less frequently used ink therein. The first channel has a longer channel length than the second channel. The drive frequency setting section sets a higher drive frequency for the channel holding the more frequently used ink.
An adjacent dot detector determines whether adjacent dots in the dot data are of different colors. If the adjacent dots are of different colors, a gradation comparator determines whether a gradation level of one of the colors is higher than a predetermined setting.
A gradation converter converts gradation levels higher than the predetermined setting to a lower gradation level and the drive frequency setting section sets the drive frequency in accordance with the conversion of gradation.
The recording apparatus includes a speed setting section which sets a scanning speed of the recording head in a main scanning direction. Another second setting section sets a scanning speed of the recording head in a sub scanning direction. These scanning speeds are determined in accordance with the timing.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicting preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: 5557304 (1996-09-01), Stortz
patent: 5604526 (1997-02-01), Kwak
patent: 5614931 (1997-03-01), Koike et al.
patent: 5689291 (1997-11-01), Tence et al.
patent: 5790152 (1998-09-01), Harrington
patent: 5907331 (1999-05-01), Markham
patent: 5917510 (1999-06-01), Narushima
Ikeda Kiyoshi
Kishimoto Mitsuru
Kobayashi Hideyuki
Ooishi Noboru
Hsieh Shih-Wen
Le N.
Oki Data Corporation
Rabin & Champagne, P.C.
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