Thermal head

Details Thermal head Thermal head

2002-11-25

2004-04-13

Nguyen, Judy (Department: 2853)

Incremental printing of symbolic information

Ink jet

Ejector mechanism

C347S202000, C347S203000, C347S204000

Reexamination Certificate

active

06719407

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a thermal head for use in thermal printers, and more particularly, to a thermal head capable of preventing degradation in print quality, caused by adherence of dirt or the like.
Generally, a thermal head as a recording head mounted on a thermal printer or the like comprises a plurality of heating elements composed of a heating resistor and aligned in a row on a substrate, and the heating elements are selectively energized according to printing information to generate heat, thereby melting ink on an ink ribbon to heat transfer the same to regular paper, paper for OHP (overhead projector), or the like, or to cause a thermal recording paper to take color, so that printing on recording media of various kinds is performed.
With such conventional thermal head, it is general as shown in
FIG. 3
that a heat reserving layer
12
is formed on an upper surface of a radiating substrate
11
and a projection
12
b
is formed on an upper surface of the heat reserving layer
12
and near one end
11
a,
which constitutes a right side end of the substrate
11
, to project a predetermined height.
Also, a heating resistor
13
is laminatingly formed on the upper surface of the heat reserving layer
12
, and a common electrode
14
and an individual electrode
15
are formed on the left and right of the heating register
13
to supply electric power energy to the heating resistor
13
.
A plurality of heating elements
13
a
are aligned in a dot-shaped manner and formed in a location between the common electrode
14
and the individual electrode
15
of the heating resistor
13
.
Also, protective layers (not shown) are laminatingly formed on upper surfaces of the heating elements
13
a,
the common electrode
14
and the individual electrode
15
to prevent oxidation and abrasion of the heating elements
13
a,
and the respective electrodes
14
,
15
.
Also, as shown in
FIG. 4
, a driver IC
16
is arranged on a left side of the projection
12
b
in the figure and near the other end
11
b
of the substrate
11
to be connected to the common electrode
14
and the individual electrode
15
.
Also, a terminal portion
17
formed from a FPC (flexible substrate) or the like is taken out from the other end
11
b
of the substrate
11
.
With such conventional thermal head, the substrate
11
is mounted on a head mount (not shown) to be mounted on a thermal printer for printing, at which the head mount is turned to bring the thermal head into pressure contact with a platen (not shown), whereby the heating elements
13
a
can be brought into pressure contact with, for example, an ink ribbon
18
.
In the case where a printer mounting thereon the conventional thermal head described above is a thermal transfer printer, the thermal head
11
is lowered to bring the heating elements
13
a
into pressure contact with the ink ribbon
18
and to move the thermal head
11
in a direction indicated by an arrow A.
Then, the heating elements
13
a
is caused on the basis of printing information to selectively generate heat to heat the ink ribbon
18
, whereby ink on the ink ribbon
18
is transferred to a recording sheet
19
to afford printing characters, images or the like on the recording sheet
19
.
Also, with a thermal transfer printer of line type, printing on the recording sheet
19
can be performed while moving the ink ribbon
18
and the recording sheet
19
in a direction indicated by an arrow B without moving the thermal head.
With conventional thermal heads, however, recesses
12
c,
12
d
are produced on the surface of the heat reserving layer
12
and on right and left feet of the projection
12
b
of a predetermined height in the figure.
Therefore, when ink in the ink ribbon
18
is transferred to the recording sheet
19
placed on a platen (not shown) for printing while the thermal head
11
with its head lowered is moved in the direction of the arrow A, it is feared that foreign matters, such as fine dirt or the like, attaching to the ink ribbon
18
accumulate in the recess
12
c
on a left side of the heating elements
13
a
in the figure and upstream of the projection
12
b
in the direction of movement indicated by the arrow A.
When foreign matters such as dirt or the like accumulate in the recess
12
c
on the left side of the heating elements
13
a
in the figure as described above, it is feared that striped white lines or the like are generated on a picture image printed on the recording sheet
19
under the influence of dirt or the like to cause degradation in quality of printing.
Also, in the case where printing is performed while the ink ribbon
18
and the recording sheet
19
are moved in the direction of the arrow B and without moving the thermal head
11
, it is feared that foreign matters such as dirt or the like accumulate in the recess
12
c
on the left side of the heating elements
13
a
in the figure.
SUMMARY OF THE INVENTION
The invention has been thought of in view of the above problem, and has its object to provide a thermal head capable of performing printing of high quality by preventing foreign matters such as dirt or the like at the time of printing to accumulate in a location where a heat reserving layer is formed.
The invention provides, as first solving measures for solving the above problem, a thermal head comprising a heat reserving layer formed on a surface of a substrate, a plurality of heating elements formed on an upper surface of the heat reserving layer, an individual electrode and a common electrode for supplying electricity to the heating elements, and a protective layer covering at least upper surfaces of the heating elements, the individual electrode and the common electrode, and wherein the heat reserving layer comprise a projection formed by partially projecting a surface of the layer, the heating elements being provided on a surface of the projection, and the projection is shaped in cross section in a direction perpendicular to a direction of arrangement of the heating elements to form an inclined surface on one surface side thereof, the other surface side thereof being formed to be flat in substantially the same height as that of a top of the projection.
Also, as second solving measures for solving the above problem, a height of the projection from the one surface side is 5 to 50 &mgr;m.
Also, as third solving measures for solving the above problem, the common electrode is formed on the one surface side and the individual electrode is formed on the other surface side.


REFERENCES:
patent: 5091736 (1992-02-01), Narita
patent: 6614460 (2003-09-01), Susukida et al.
patent: 4422975 (1995-01-01), None
patent: 7-81113 (1995-03-01), None
patent: 8-80628 (1996-03-01), None

Affiliated with

Also associated with

Rating

Thermal head does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Thermal head, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermal head will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3253517