Incremental printing of symbolic information – Thermal marking apparatus or processes – Multicolor
Reexamination Certificate
2001-01-03
2002-09-17
Barlow, John (Department: 2861)
Incremental printing of symbolic information
Thermal marking apparatus or processes
Multicolor
C347S217000
Reexamination Certificate
active
06452619
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a thermal transfer recording apparatus and method for thermal transfer recording for transferring and recording thermal transfer recording material of a thermal transfer recording medium on a printing medium utilizing heat generation of a heat generating element of a line type thermal head.
With regard to a thermal transfer recording apparatus, for example, it is known in Jpn. Pat. Appln. KOKAI Publication No. 59-188452. As shown in
FIG. 16
, it comprises print units
101
,
102
,
103
and
104
of yellow, magenta, cyan and black, respectively, which are disposed in this order along a straight conveyance path
106
for a printing medium
105
.
The print unit
101
for yellow includes a line type print head
101
-
1
utilizing a thermal head, a thermal transfer recording mechanism having spools
101
-
3
for supplying an yellow ribbon as a thermal transfer recording medium
101
-
2
including yellow ink over a heating face of a heat generating element constituting the line type print head
101
-
1
and a transfer pressure roller
101
-
4
.
The other print units
102
to
104
have the exactly same structure as the yellow print unit
101
described above except the color to be used for thermal transfer recording medium, i.e., magenta, cyan and black, respectively; and comprise line type print head
102
-
1
,
103
-
1
and
104
-
1
, respectively, thermal transfer recording mechanism having spools
102
-
3
,
103
-
3
,
104
-
3
, respectively, for supplying the thermal transfer recording medium
102
-
2
,
103
-
2
,
104
-
2
, respectively, over the heating face of the heat generating element constituting the line type print head, respectively, and the transfer pressure roller, respectively.
It is arranged that a printing medium
105
is conveyed from the feed rollers
107
and the yellow print unit
101
toward the black print unit
104
on the conveyance path
106
and among each print
101
to
104
, and it passes through between the thermal recording media
101
-
2
to
104
-
2
and the transfer pressure rollers
101
-
4
to
104
-
4
.
When carrying out recording, while conveying the printing medium
105
from the yellow print unit
101
through to the black print unit
104
, yellow is transferred first at the yellow print unit
104
. When the transferred portion comes to the heating face of each print head
102
-
1
to
104
-
1
on each print unit
102
to
104
, each color is transferred synchronously overlapping in order. At this time, colors are overlapped and mixed, thus it is made possible to record a desired hue.
As described hereinbefore, in a thermal transfer recording in which three or four print units are provided and each print head prints a specific color, different from a method in which only one print head prints a plurality of colors, as a printing medium
105
is not reciprocally conveyed frequently, it is made possible to carry out a high speed recording.
Also, in Jpn. Pat. Appln. KOKAI Publication No. 10-226178, it is disclosed that a thermal transfer recording medium of which dynamic modulus of elasticity at 70° C. is 1×10
6
to 1×10
10
in order to form a recorded image excellent in abrasion resistance and heat resistance using a line type thermal head.
Further, in Jpn. Pat. Appln. KOKAI Publication No. 8-52942, it is disclosed that a thermal transfer recording medium of which loss tangent tan &dgr; measured by viscoelasticity measurement of ink layer at 60° C. to 100° C. is within a range of 0.4 to 2.5 is used in order to make a clear thermal transfer recording on a plan medium to be transferred at a low cost.
Furthermore, in a thermal transfer recording apparatus utilizing a serial type thermal head, for example, a thermal transfer recording medium is pressed to bring the same into contact with a printing medium with a large line pressure of approximately 2.0 N/mm. Line pressure means load per unit length in the direction of the arrangement of the heat generating elements. It is known that even when the smoothness of the surface of the printing medium is low (coarse), unevenness of the surface is made smooth and the adhesiveness of the thermal transfer recording medium is increased. Further, in a thermal transfer recording apparatus utilizing a serial type thermal head, thermal transfer recording medium such as an ink ribbon is narrow in width and it is made possible to be compact in size and to be stored in a cassette. As a result, it provides an advantage that wrinkles are hardly generated on the thermal transfer recording medium even when a relatively large line pressure is given thereto.
Whereas, in a line type thermal head mounted with a line type thermal head, a line type thermal transfer recording medium was prepared utilizing the same technique as that for conventional thermal transfer recording medium, and the thermal transfer recording material in a softened or melted status by a heat from a thermal head was peeled off from the thermal transfer recording medium before it cooled down to a room temperature to a printing medium under conveyance, of which smoothness of the surface is low (coarse). As a result the following problems were found, i.e., ink was not transferred well onto the unevenness on the surface of the printing medium, and it was unstable; the edge of the recorded image was not sharp but zigzag resulting in a low quality of the recorded image. However, when a recorded image is required a dimensional accuracy, or when a high resolution recorded image is required, for example, bar code or OCR (Optical Character Recognition) etc which carry out reading process of a recorded image information with an optical means after recording, quality of the edge becomes essential. Still further, when a color recording in which a plurality of thermal transfer recording materials of different colors are transferred overlapping in order, due to not only smoothness of the surface of a printing medium but also the thermal transfer recording material of the thermal transfer recording medium previously transferred thereto, the edge of the recorded image may become zigzag. A problem is that desired recorded image can not be obtained.
Furthermore, another problem is: when a large line pressure is given to a line type thermal head same as a serial type thermal head used in a thermal transfer recording apparatus in order to increase the adhesiveness between the thermal transfer recording material of a thermal transfer recording medium and a printing medium, as the width of the thermal transfer recording medium is wider than that of the serial type, it is difficult to apply an even line pressure over the full width of the thermal transfer recording medium. As a result, wrinkles are easily generated resulting in a low quality of the recorded image.
As described hereinbefore, such problems exist that, when a thermal transfer recording material in a softened or melted status by a heat from the heat generating elements on a line type thermal head is peeled off from the supporting material of the thermal transfer recording medium and transferred to a printing medium under conveyance before it cools down to a room temperature, if the line pressure of the head is increased, wrinkles are generated; while if the line pressure is reduced to prevent the wrinkles from being generated, it causes an unstable transfer and a high quality recorded image can not be obtained.
BRIEF SUMMERY OF THE INVENTION
An object of the present invention is to provided a thermal transfer printing apparatus utilizing a line type thermal head provided with a plurality of heat generating elements disposed thereon, which enables to obtain a high quality recorded image with sharp edges.
Another object of the present invention is to provided a method for thermal transfer printing utilizing a line type thermal head provided with a plurality of heat generating elements disposed thereon, which enables to obtain a high quality recorded image with sharp edges.
In accordance with the present invention, a thermal transfer record
Endo Mitsuharu
Kushida Hiroyuki
Barlow John
Feggins K.
Frishauf Holtz Goodman & Chick P.C.
Toshiba Tec Kabushiki Kaisha
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