Thermal columnar-aligned, plural-heaters print head

The invention relates to a thermal printing head having a plurality of heating elements arrayed in both column and row directions, which can be driven selectively and independently. A first column group is comprised of two or more columns each having heating elements which are aligned in the row direction, and which can be independently sequentially driven. A second column group is comprised of two or more columns, also having heating elements aligned in the row direction, but with the rows being offset in the column direction as compared with the rows of the first column group. The arrangement allows the double printing of each printable dot, yet facilitates the wiring of the individual heating elements by providing a larger space between adjacent rows and column groups.

This invention relates to a thermal printer head, and more particularly to 
a thermal printer head comprising plural heating-element-columns each 
including plural aligned heating elements. 
In a conventional thermal printer head, there are positioned two 
heating-element-columns parallel to each other with each of the 
heating-element-columns including a plurality of aligned heating elements. 
In each heating-element-row, two heating elements positioned in the same 
row but in different columns are driven (heated) in response to the same 
data to be recorded on the recording medium at different time points, and 
are driven at the same time point (simultaneously) in response to data 
corresponding to two dot-points adjacent to each other on the recording 
medium. The different time points have a time period corresponding to the 
time in which the recording medium is shifted by a distance equal to a 
pitch of the two heating elements, whereby dots to be formed by the two 
heating elements are recorded on the same dot point of the recording 
medium. 
However, such a conventional thermal printer head has the following 
disadvantages: It is difficut to wire the current supply lines (lead 
lines), becauses it is hard to provide a sufficiently broad space between 
the heating elements in both (row and column) directions, because the 
heating elements are quite close to one another in both directions. 
Further, since the heating elements in the two columns may be driven 
simultaneously, driving electric current must be applied simulataneously 
to the heating elements in the two columns, and so a large peak current is 
required. 
It is, therefore, an object of this invention to provide a thermal printer 
head comprising plural heating-element-columns each including aligned 
plural heating elements, in which a broader space for wiring lead lines 
can be provided and wherein a great peak current for driving the thermal 
printer head is not required. 
According to this invention, a thermal printer head for recording on a 
recording medium in response to recording data comprises a first 
column-group having a plurality of first heating-element-columns, and a 
second column-group provided apart from the first column-group and having 
a plurality of second heating-element-columns. Each heating-element-column 
in the first and second column-groups includes a plurality of heating 
elements lined up in a first direction. In each of the first and second 
column-groups, the heating elements in different heating-element-columns 
are lined up in a second direction perpendicular to the first direction to 
provide a plurality of first heating-element-rows and a plurality of 
second heating-element-rows, respectively. The first and second 
heating-element-rows are displaced from each other in the first direction 
by a distance equal to one-half of a pitch of the heating elements in each 
column in the first direction.

Referring to FIG. 1, the first embodiment of this invention comprises first 
and second column-groups 10 and 20. The first column-group 10 has two 
first heating-element-columns A and B. Each of the first 
heating-element-columns A and B includes a plurality of first heating 
elements 11 (11A and 11B) lined up in a vertical direction. The two first 
heating elements 11A and 11B adjacent to each other in the first 
heating-element-columns A and B are lined up in a horizontal direction, 
that is, in a head moving direction to provide a plurality of first 
heating-element-rows 10R (10R-1, 10R-2, 10R-3, . . . ). The second 
column-group 20 has two second heating-element-columns C and D. Each of 
the second heating-element-columns C and D includes a plurality of second 
heating elements 21 (21C and 21D) lined in the vertical direction. The two 
second heating elements 21C and 21D adjacent to each other in the second 
heating-element-columns C and D are lined up in the horizontal direction 
to provide a plurality of second heating-element-rows 20R (20R-1, 20R-2, 
20R-3, . . . ). The first and second heating-element-rows 10R and 20R are 
displaced to each other in the vertical direction by a distances to 
one-half of a vertical pitch P.sub.V of the heating elements so that 
productions thereof are sandwiched with each other. 
In eah heating-element-row, a horizontal pitch (element-to-element pitch) 
P.sub.H of the heating elements is determined to be equal to a dot pitch 
P.sub.D of dots to be recorded on a recording medium (not shown). A 
column-group pitch P.sub.G between the first and second column-groups is 
determined to be equal to a distance multiplied the horizontal pitch 
P.sub.H by (n+0.5) where n is an integer), for example, 4.5 P.sub.H in 
this embodiment 
The first embodiment further comprises a common lead 30 connected to one 
end of all the heating elements 11 and 21, and a plurality of signal 
supplying leads 40 respectively connected to the other end of all the 
heating elements 11 and 21. Driving signals for heating the heating 
elements 11 and 21 are supplied through the signal supplying leads 40 in 
response to recording data. 
A recording operation of this thermal printer head according to the first 
embodiment will be described with reference to FIG. 2 showing timing 
charts of the driving signals to be applied to the heating elements in the 
heating-element-columns A, B, C and D. 
At a first phase of a timeing period (T), the driving signals for a 
recording column (n) on the recording medium are applied to the heating 
elements 11A in the heating-element-column A in response to recording 
signals S(n) representative of recording dots to be recorded in the 
recording column (n). In this phase, the heating elements 11B are also 
driven in response to the recording signals S(n-1) for the recording 
column (n-1) to record dots at positions in the recording column (n-1), on 
which dots had been recorded by the heating elements 11A in the first 
phase of the previous timing period (T-1) in response to the recording 
signals S(n-1). Similarly, at each first phase in the sequential timing 
periods, the heating elements 11A are driven in response to the recording 
signals S(n+i) to record in the recording column (n+i), and simultaneously 
the heating elements 11B are driven in response to the recording signals 
S(i-1) to record in the recording column (n+(i-1)), on which the heating 
elements 11A had recorded in the previous timing period. Thus, the first 
dot-rows are recorded along the first heating-element-rows 10R on the 
recording medium, while the thermal printer head is moved in the 
horizontal direction in synchronism with the timing periods. 
In a second phase of the timing period (T) after the thermal printer head 
has been moved in the horizontal direction by a distance equal to one-half 
of the horizontal pitch P.sub.H (1/2P.sub.H), the driving signals for a 
recording column (n+5) on the recording medium are applied to the heating 
elements 21C in the heating-element-column C in response to recording 
signals S(n+5) representative of recording dots to be recorded in the 
recording column (n+5). In this phase, the heating elements 21D are also 
driven in response to the recording signals S(n+4) for the recording 
column (n+4) to record dots at positions in the recording column (n+4), on 
which dots had been recorded by the heating elements 21C in the first 
phase of the previous timing period (T-1) in response to the recording 
signals S(n+4). Similarly, at each first phase in the sequential timing 
periods, the heating elements 11A are driven in response to the recording 
signals S(n+i+5) to record in the recording column (n+i+ 5), and 
simultaneously the heating elements 21D are driven in response to the 
recording signals S(i+4) to record in the recording column (n+(i+4)), on 
which the heating elements 21C had recorded in the previous timing period. 
Thus, the second dot-rows are recorded along the second 
heating-element-rows 20R on the recording medium, while the thermal 
printer head is moved in the horizontal direction in synchronism with the 
timing periods. 
Since the first and second heating-elements-rows 10R and 20R are displaced 
from each other by a distance equal to one-half of the vertical pitch 
P.sub.V (1/2P.sub.V), the second dot-rows are positioned between the first 
dot-rows, to thereby complete the dot matrix. 
Referring to FIG. 3, the second embodiment of this invention is identical 
to the first embodiment except that the horizontal pitch 
(element-to-element pitch) P.sub.H ' is 1.5P.sub.D, and column-group pitch 
P.sub.V ' is 5P.sub.D. 
The second embodiment is supplied with driving signals having the timing 
shown in FIG. 4, by which the heating elements 11A and 21C are driven 
simultaneously at the first phase of each timing period, and the heating 
elements 11B and 21D are driven simultaneously at the second phase of each 
timing period. 
According to this invention, since the first and second column-groups are 
positioned apart from each other, it is easy to maintain a broader space 
for the wiring of the leads. Further, because only one-half of all the 
heating elements are driven simultaneously, a great peak electric current 
is not required.