Incremental printing of symbolic information – Thermal marking apparatus or processes – Density control
Reexamination Certificate
1998-08-05
2001-04-24
Le, N. (Department: 2861)
Incremental printing of symbolic information
Thermal marking apparatus or processes
Density control
C347S240000, C347S251000
Reexamination Certificate
active
06222573
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a recording apparatus, in particular, to a heat transfer recording apparatus using an ink film wherein characters and/or graphic images are formed on recording paper of various widths.
2. Description of the Related Art
A heat transfer recording apparatus such as a printer comprises a platen roller and a thermal head that can be arbitrarily pressed against the platen roller. The recording paper is transferred together with the ink film between the platen roller and the thermal head to allow characters and/or graphic images printed thereon. The ink film has thermally fusing or sublimating type of inks coated on one side thereof. The ink is fused or sublimated to be fixed on the recording paper by means of the heat of the thermal head.
A heat transfer recording apparatus is normally capable of printing onto various sizes of recording paper. For example, recording paper larger than A4 in addition to paper of sizes as small as A6 paper, post card, card-size paper can be optionally applied to the recording apparatus.
However, a problem has been noticed of such an apparatus that, after having been used for some time, the printing density becomes uneven across the width of the paper depending on how often the apparatus has been used. More specifically, when an image of a uniform density is printed on a wide sheet of recording paper, the printed image becomes darker in the midsection of the paper than on the edges of the width.
It is caused by the fact that the midsection of the platen roller and the thermal head where all sizes of paper pass wear more rapidly than the edges where only larger sizes of paper pass, thus increasing the heat conductivity in the midsection.
This problem can be eliminated by replacing the platen roller and/or thermal head when it is found that the density unevenness develops between the midsections and the edges of the recording paper. However, this method is not recommendable because of the resultant increase of the running cost.
SUMMARY OF THE INVENTION
The purpose of the invention is to prevent the density unevenness developing between the midsections and the edges of a recording paper on a recording apparatus that forms images on the paper of different sizes using the ink film with ink layers formed thereon.
One aspect of the present invention is a recording apparatus for forming images on recording paper with varying widths using an ink film with ink layers formed thereon, the recording apparatus comprising a density controller that makes density compensation in a range which corresponds to difference in width between wide recording paper and narrow recording paper.
Another aspect of the present invention is a recording apparatus for forming images on recording paper with varying widths using an ink film with ink layers formed thereon, the recording apparatus comprising: a detector which detects image density in a plurality of different positions of recording paper; a calculator which calculates density compensation amount based on the detected image density; and a density controller which makes density compensation corresponding to the calculated density compensation amount.
The objects, features, and characteristics of this invention other than those set forth above will become apparent from the description given herein below with reference to preferred embodiments illustrated in the accompanying drawings.
REFERENCES:
patent: 4462680 (1984-07-01), Ikeda
patent: 5974229 (1999-10-01), Yoshino
patent: 6055011 (2000-04-01), Nishimura
patent: 7-68823 (1995-03-01), None
Katsuda Takeo
Shibuki Takashi
Le N.
Minolta Co. , Ltd.
Pham Hai C.
Sidley & Austin
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