Incremental printing of symbolic information – Thermal marking apparatus or processes – Multicolor
Reexamination Certificate
1998-09-14
2001-05-15
Le, N. (Department: 2861)
Incremental printing of symbolic information
Thermal marking apparatus or processes
Multicolor
Reexamination Certificate
active
06232993
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to tape printers which form a full color image on a heat-sensitive ray-responsive printing medium which is colored with heat energy and whose coloring is stopped by irradiation of rays of a specified wavelength, and a printing medium containing a cassette settable in such tape printer.
Conventionally, various printing systems have been proposed. Typical printing systems put to practical use in offices or households at present are an electronic photograph system, an ink-jet system, and in thermal system.
Recently, the demand for a color printing image has increased. Any one of the above-mentioned printing systems has improved in various respects so as to satisfy the demand for a color printing image and its printing quality has reached a sufficiently practical level. Recently, in addition to improvements to the printing quality, further inexpensive printing devices are desired.
A dominant printing method employed at present in the respective printers of the above systems is to use a cut sheet of paper to print data on it and not to print vouchers/added-up data mainly on continuous paper as in the past, from a standpoint of high speed printing and document printing. Among the above printing systems, printing mechanisms of the thermal system are very frequently incorporated into printers which are intended for cost reduction or into printers enough to perform small-sized printing because the structure of their thermal heads which perform printing is simple.
The printers of the thermal system include ones of a heat-transfer system using an ink ribbon and of a heat-sensitive system using heat-sensitive paper used generally, for example, in fax. The printers of the heat transfer system are mainly employed for color printing. However, in the case of the printers using an ink ribbon, generally, its printing rate is about 5% even when sentences are printed, for example, using a monochromatic (for example, black) ink ribbon, so that 95% of the ink ribbon is discarded without being used. Thus, the ink ribbon is wastefully used. Much more in the color printing, the respective colors of a plurality of color ink ribbons have been used only partially as the colors of the whole paper surface and discarded, so that the ink ribbons have been given a wide berth as producing very much waste. Recently, the ink-jet systems have gained power as simple color printers, but must be improved in terms of oozing and drying of the printing ink.
In such background, a new printing system which records (forms) a full color image, using a printing medium which includes three (yellow, magenta, cyan) heat-sensitive coloring layers formed on an appropriate sheet-like base material on the basis of the above-mentioned heat-sensitive system, is proposed by Japanese Patent Publication Tokkohei 4-10879 and 6-51425, and put partially to practical use. The yellow or magenta coloring layer includes a color former coated uniformly on a base material. The color former includes a dispersed phase in which compounds containing in molecules active methylene called a coupler and a diazonium salt exist in a mixed manner as particles on the order of micron. The couplers are activated by heat of a predetermined temperature or more so that the compounds and the diazonium salt react in a basic atmosphere to form a yellow or magenta coloring matter. The diazonium salt is dissolved with rays of a specified wavelength (ultra-violet rays) to lose the function of reacting with the couplers. The cyan coloring layer includes a color former coated uniformly on the base material, the color former including a dispersed phase in which particles of leuco coloring matters on the order of micron and developers exist in a mixed manner. This cyan layer reacts with the aid of heat of a predetermined temperature or more to be colored.
FIG. 25
shows one example of conventional heat-sensitive recording devices (printers) which form an image on the above-mentioned printing medium (heat-sensitive ray-responsive recording paper), disclosed in Japanese Patent Publication Tokkohei 6-51425.
In the heat-sensitive recording device of
FIG. 25
, a roll of recording paper
1
is brought at a portion
1
′ into close contact with the peripheral surface of a drum
3
through a paper feed roller
2
, and the recording paper portion
1
′ is then carried by the drum
3
in a direction of arrow n or r below a thermal head
4
and a light source unit
5
. The thermal head
4
extends in the form of a line along the longitudinal axis of the drum
3
(perpendicular to the face of the
FIG. 25
sheet). The light source unit
5
includes in a housing
5
a
a light source
5
b
which emits rays in a predetermined frequency band and a filter
5
c
provided below the light source
5
b
which selects rays of each of different wavelengths corresponding to yellow and magenta to irradiate the recording paper with the rays. Feed rollers
6
, a cutter
8
and a discharged paper tray
7
are provided to the right of the dram
3
.
FIG. 23
is a cross-sectional view of recording paper used in the heat-sensitive recording device.
FIG. 24
shows the relationship between the coloring density of each of the coloring layers of the recording paper and heat energy applied to that coloring layer.
The recording paper
1
of
FIG. 23
is of a heat-sensitive ray-responsive type and includes paper of three heat-sensitive coloring layers; that is, a yellow layer
1
—
1
, a magenta layer
1
-
2
, a cyan layer
1
-
3
layered uniformly on a sheet-like supporting base material
1
-
4
with a heat-resistive protective layer
1
-
5
provided on the yellow layer
1
—
1
. In each of the yellow, magenta, and cyan layer
1
—
1
,
1
-
2
and
1
-
3
, its main coloring materials contained in small heat-responsive capsules of a diameter of about 1 &mgr;m are distributed along with other components in a binder material. As shown in
FIG. 24
, in order to control coloring of three primary colors with heat energy, the heat sensitivities of the respective couplers are designed so as to decrease in order of yellow (Y), magenta (M) and (C) layers (that is, the yellow layer is colored at the lowest temperature) to thereby record image data on the basis of coloring of yellow, magenta and cyan. However, if such heat sensitivity differences are only provided for the respective layers, and even when, for example, only magenta is intended to be colored, magenta as well as yellow would be colored because heat energy required for coloring the magenta will necessarily color even yellow which requires less coloring heat energy than the magenta. Thus, a desired color cannot be obtained. In order to avoid this problem, the upper two layers contain in a mixed dispersed manner components that prevent the upper two layers from being colored by the respective next higher coloring heat energy after the upper two layers are respectively colored, or nullify their colorability by respective rays of specified wavelengths (ultraviolet rays), that is, fix their colored states.
Thus, first, in
FIG. 25
, the thermal head
4
selectively produces a heat quantity suitable for a coloring layer which is colored at the lowest temperature (ordinarily, the yellow coloring layer) while coloring a corresponding (yellow) image on a recording paper portion
1
′ carried in the direction of arrow n by a forward rotation of the paper feed roller
2
. The roller
2
then feeds out the recording paper
1
until the recording paper portion on which the (yellow) image has been colored reaches at its trailing end a position below the power source unit
5
. The paper feed roller
2
is then rotated in a reverse direction to carry the recording paper
1
′ in the direction of arrow r while the light source
5
b
emits with ultraviolet rays of a specified wavelength whose emission peak is 420 nm onto the first layer (yellow colored layer) of the just colored recording medium paper portion through the filter
5
c
from the light source
5
b,
the ultraviolet rays acting only on t
Igarashi Kenji
Ikeda Masayuki
Ito Kenzo
Kobayashi Kenji
Takeuchi Kensaku
Casio Computer Co. Ltd.
Feggins K.
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Le N.
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