Incremental printing of symbolic information – Thermal marking apparatus or processes – Specific resistance recording element type
Reexamination Certificate
2000-03-03
2001-04-17
Tran, Huan (Department: 2861)
Incremental printing of symbolic information
Thermal marking apparatus or processes
Specific resistance recording element type
Reexamination Certificate
active
06219079
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin-film thermal head for use in a thermal recording operation, and more particularly to improvement in a thin-film thermal head incorporating a resistance heating layer and a conductive layer.
2. Description of the Related Art
A thin-film thermal head
1
which is a subject of the conventional technique and the present invention, as shown in
FIG. 2
, incorporates graze projections
2
formed in a line facing the central axis
0
of rotation of a platen
3
. When a recording material
4
has been inserted into a space between a platen
3
and the graze projections
2
, the graze projections
2
corresponding to an image, which must be printed, are selectively heated. Thus, the image is, through a toner ribbon
5
, thermally transferred to the image receiving surface of the recording material
4
.
FIG. 3
is an enlarged cross sectional view showing a portion in the vicinity of the graze projection
2
shown in FIG.
2
.
As shown in
FIG. 3
, the graze projection
2
incorporates a projecting graze layer
22
formed on a ceramic substrate
21
. Moreover, a resistance heating member
23
, a conductor layer
24
and a protective layer
25
are laminated on the graze layer
22
. The conductor layer
24
is sectioned at the top surface of the graze layer
22
such that the two sections are formed away from each other for distance A so that a pair of electrodes is formed. When an electric current is supplied to a space between the conductor layers
24
which are the pair of electrodes, the resistance heating member
23
generates heat. The graze projection
2
is structured to cause the resistance heating member
23
between the conductor layers
24
to generate heat to record an image on the recording material
4
.
The conventional thin-film thermal head has the structure that the conductor layer
24
is made of aluminum (Al). However, Al having somewhat high resistance suffers from a problem because a conductor layer having low resistance is required so as to be adapted to a thin-film thermal head having a resolution higher than 600 dpi because the recording density has been raised in recent years.
As an element having resistance lower than that of AL, Cu is a known element. When a conductor layer is constituted by using only Cu, the density can be raised because Cu has low resistance. The conductor layer made of only Cu, however, raises a problem in that separation of the film frequently occurs when, for example, the temperature is high. Thus, manufacturing yield deteriorates.
SUMMARY OF THE INVENTION
In view of the foregoing, an object of the present invention is to provide a thin-film thermal head which is capable of simultaneously lowering the resistance and raising the manufacturing yield.
To achieve the above-mentioned object, according to a first aspect of the present invention, there is provided a thin-film thermal head comprising a resistance heating layer and a conductor layer, wherein the main component of the conductor layer is a Cu—Ag alloy.
According to a second aspect of the present invention, there is provided a thin-film thermal head having a structure according to the first aspect, wherein the conductor layer contains Cu by 50 atom % or higher, Ag by 0.5 atom % or higher and 50 atom % or lower and other elements by 2 atom % or lower.
According to a third aspect of the present invention, there is provided a thin-film thermal head having a structure according to the first aspect or the second aspect, wherein pitches of heating elements are 43 &mgr;m or shorter.
REFERENCES:
patent: 5709958 (1998-01-01), Toyoda et al.
patent: 6001461 (1999-12-01), Toyoda et al.
patent: 4-238043 (1992-08-01), None
Fuji Photo Film Co. , Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
Tran Huan
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