JPS6384948A - High-density thermal line head - Google Patents

Abstract

PURPOSE:To obtain a high-density thermal head by providing first and second rows of driver electrodes, with their phases shifted to each other in a main scan direction and forming a zigzag-shaped do generation part between heating elements. CONSTITUTION:On both sides of two strip thermal resistors 32, driver electrodes 40a, 40b are connected by arrangement of first and second rows, and these driver electrodes are arranged on both sides of the thermal resistors in such a manner that they are shifted by a space which is equivalent to 1/2 of the pitch of adjoining driver electrodes 40a or 40b. Then if a drive signal is applied to a driver circuit 42a which corresponds to one of the driver electrodes 40a in the first row, an electric current runs between the thermal resistors on the left of the two strip thermal resistors 32. Consequently, this energization results in the formation of a single dot on printing paper by the formation of a thermal part. In the same manner, if a drive signal is applied to a driver circuit 42b which corresponds to one of the driver electrodes 40b in the second row, a single dot is formed on printing paper. Thus the density of dots printed on printing paper becomes exceedingly high, providing a high-quality print.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal printer, and more particularly to a high-density thermal line head that increases the density of printed dots by a thermal printer.

[Prior art]

In a thermal printer, a heating element and a large number of common electrodes and driver electrodes arranged at equal pitches are arranged facing each other in the main scanning direction to heat the printing paper that is guided and supported by a platen. Alternatively, printing heads arranged alternately are provided, and the heating effect of the heating element is controlled by supplying electricity between the electrodes through a heating element, and the heating element is pressed against the printing paper through the thermal ink medium. Characters, symbols, etc. corresponding to the printing input are printed as dots on the printing paper.

[Problems to be solved]

In this case, dots are formed on the printing surface when printing dots according to thermal transfer by the heating element while the printing head is moved along the main scanning movement in the axial direction of the platen, that is, in the direction of the printing paper. The density is limited by the arrangement density when arranging and connecting the above-mentioned common electrode and driver electrode to the heating element, and when manufacturing these electrode patterns, it is difficult to increase the density if the patterns are arranged in a row. The more you try to do this, the lower the manufacturing yield will be, and the more advanced technology will be required, the higher the manufacturing cost will be.The present invention therefore provides a high-density thermal head that solves the above problems. That is.

[Solution]

In view of the above-mentioned object of the invention, the present invention provides a thermal line head that moves in the main scanning direction intersecting the paper feeding direction by the platen and transfers ink to printing paper according to heat generation control of a heating element. forming a substantially central portion of a strip-shaped heating element extending in the scanning direction at a connection portion with a common electrode, and arranging a first driver electrode array and a second driver electrode array along both side edges of the strip-shaped heating element; At this time, the first and second driver electrode arrays are provided with phases shifted from each other in the main scanning direction, and a staggered dot generation portion is formed between them and the heating element to increase printing density. The present invention provides a high-density thermal line head having a configuration in which the common electrode is formed of a layered body connected to the lower surface side of the band-shaped heating element, and The column provides a high-density thermal line head arranged and connected to the upper surface of the strip-shaped heating element to perform printing with a high dot density per unit length during main scanning movement. It is something. below,
The present invention will be explained in more detail based on the accompanying drawings.

〔Example〕

First, prior to the embodiments of the present invention, the structure of a conventional thermal line head will be briefly explained. As shown in FIG. is provided in the main scanning direction of the head, and as a means for generating a heat generating part in this heat generating element 12, common electrodes 14 are arranged at equal pitches on one side of the heat generating element 12, as shown in an enlarged view in FIG. The driver electrodes 16 are arranged in rows on the other side of the heating element 12 at equal pitch intervals.
In addition, the common electrodes 14 and the driver electrodes 16 are arranged in an alternating arrangement, and a drive signal is applied to the driver electrode 16 between one common electrode 14 and the driver electrode 16 adjacent to the common electrode 14 to connect the two electrodes 14 and 16. When electrically energized,
The heating element between the two electrodes generates heat, and when this heating element is pressed against the photographic paper being fed by a platen (not shown) facing the head through a thermal ink medium (not shown), a single image is generated on the photographic paper. Since one dot is printed, if a large number of such dots are formed according to the movement of the head in the main scanning direction, desired characters, figures, etc. can be printed using a group of dots. In FIG. 9, the common electrode 14 is connected to a power source via two electrical common lines 18, and each driver electrode 16 is connected to a driver circuit 22. The reason why the diode 20 is connected to each common electrode 14 is to prevent reverse current flow when the adjacent heat generating parts of the heat generating element 12 are energized from the two common wires 18 to generate heat one after another. This is what is provided for. In the case of a thermal line head consisting of such head substrate 10, heating element 12, common electrode 14, driver electrode 16, etc., the dot density in the main scanning direction is limited due to limitations in pattern formation of both electrodes 14 and 16. The limit is 16 dots per 1 mm at most, and the density of the print cannot be said to be sufficient.

On the other hand, FIG. 10 shows another example of a conventional thermal line head, in which a heating element 12 similar to the heating element 12 described above is used.
a, the row of common electrodes 14a and the driver electrode 16
The common electrodes 14a are connected to the common wires 18a, and the driver electrodes 16a each have a driver circuit 22a. When current is applied between the common electrode 14a and the driver electrode 16a in response to a drive signal, the portion of the heating element 12 between them generates heat, forming a dot. In the case of the latter conventional example, since the common electrode 14a and the driver electrode 16a are configured to face each other, the dot density is slightly higher than that described above in terms of pattern formation, but at most the dot density in the main scanning direction is The dot density is limited to 12 dots per mm. Therefore, the present invention aims to further increase the dot density of such a conventional thermal line head.

Next, embodiments of the present invention will be described.

FIG. 1 is an enlarged plan view showing a characteristic configuration of a high-density thermal line head according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view of the same, and FIG. 3 is a diagram showing such a characteristic configuration. FIG. 4 is a plan view showing the high-density dots formed by the thermal line head of the first embodiment.

First, referring to FIG. 3, a head substrate 30 of a thermal line head is shown. One surface 30a of this head substrate 30 forms a print forming surface, and a strip is formed on this print forming surface 30a. The heating resistor 32 is provided so as to coincide with the main scanning direction (direction of arrow A) of the thermal line head. The heating resistor 32 generates heat in accordance with the movement of the thermal line head in the main scanning direction to form dots on the photographic paper (not shown), just as in the conventional thermal line head described above. be. As is well known, it goes without saying that the printing paper itself is fed in the main scanning direction by a platen (not shown), and the characteristic configuration of the heating drive circuit for generating heat from the strip heating resistor 32 is the first. It is shown in enlarged view in FIGS. 1 and 2. Therefore, referring to FIG. 1 and FIG. 2, in the case of this embodiment, the above-mentioned strip heating resistor 32 is separated into two left and right strips at the center, and the center portion is divided into two strips on the left and right. It is connected to a conductor layer 34 forming a conductor, and the common conductor layer 34 is electrically connected to a common power source via a common line 36. In this embodiment, the common conductor layer 34 has a flat plate shape connected to the lower surface side of the heating resistor 32, and is arranged on the upper surface of the ceramic substrate vi38. Now, on both sides of the two strip heating resistors 32, driver electrodes 40 are arranged in first and second rows.
a and 40b are connected, and driver electrodes 4 in both rows
Both 0a and 40b are arranged at equal pitch intervals in the main scanning direction. Moreover, the first row of driver electrodes 40a and the second row of driver electrodes 40a and
The column driver electrodes 40b are arranged so as to face each other.
In addition, they are arranged so that their phases are shifted from each other in the main scanning direction.

In other words, they are arranged on both sides of the heat generating resistor 32 with a distance of 1/2 the pitch between the adjacent driver electrodes 40a or 40b. Each driver electrode 40a, 40b has a driver circuit 42a, 42b, respectively.
is connected. Also, there is no connection between the first and second row driver electrodes 40a, 40b and the common conductor N34! i layer 4
4.

According to the thermal line head configured as described above,
If a drive signal is applied to any one of the driver electrodes 40a in the first row to its corresponding driver circuit 42a, the heating resistor on the left side of the two heating resistors 32 connected to the common conductor layer 34 When conduction is established between the two and the current flows, a heat generating portion is formed and a dot is formed on the photographic paper. Similarly, any one of the driver electrodes 40b in the second row,
If a drive signal is applied to the corresponding driver circuit 42b,
The two heating resistors 32° and the right heating resistor are electrically connected and energized to form a heating portion and form a dot on the printing paper. In this way, according to this embodiment,
Two driver electrodes 40a and 40b are provided for the two strip heating resistors 32, and the first row of driver electrodes 40a and the second row of driver electrodes 40b are provided.
Since the rows of dots have a deviation of 1/2 pitch or chi, two rows of staggered dots are formed as shown in FIG. 4 as the thermal line head moves in the main scanning direction. becomes possible. In other words, the number of dots formed per unit length during one main scanning run is increased compared to the conventional case, and the dots are arranged in a staggered manner.
The density of dots printed on photographic paper has increased significantly. Furthermore, since the two heating resistors 32 are arranged extremely close to each other, even if the printing paper is fed using a single cylindrical platen, the thermal line head can main scan the staggered dots mentioned above. This can be done by shifting one gear in the direction. Moreover, since the common conductor [34 that cooperates with the driver electrodes 40a and 40b is structured three-dimensionally as a layer below the heating resistor 32, the electrical resistance value can be kept low, and therefore unnecessary Print stains on printing paper can be sufficiently reduced without increasing the heat.

5 and 6 are plan views and cross-sectional views similar to FIGS. 1 and 2 of the structure of a thermal line head according to a second embodiment of the present invention. The difference in structure of this second embodiment is that the strip heat generating resistor 32, which was separated into two strips in the first embodiment described above, is formed by a single strip heat generating resistor 132. At this time, the protrusion 134a of the common conductor layer 134 is connected so as to abut against the lower surface of this single strip heating resistor 132. The other configuration is exactly the same as the first embodiment described above, and therefore, the first row of driver electrodes 40a and the second row of driver electrodes 40b are a single strip heating resistor connected to the common conductor layer 134. It is possible to increase the dot density per unit length in the main scanning direction by cooperating with the dots 13 and 2 to form dots arranged in a staggered manner similar to that in the first embodiment. It can be done. In this second embodiment, the heating resistor 132
The fact that only one strip of driver electrodes 40a and 40b in the first and second rows is used is more advantageous than the first embodiment in that it can contribute to cost reduction in manufacturing the thermal line head. The distance between the dots can be made closer than that in the first embodiment, and as a result, the distance between the two dot rows can be made closer to each other. Therefore, the dot density per unit area on the photographic paper can be reduced. It is also advantageous in that it can be further improved.

FIG. 7 is a sectional view similar to FIG. 6 showing the main part of a third embodiment of the present invention, and this third embodiment has a single heating resistor 132 similar to the second embodiment. However, instead of the common conductor layer having a flat plate shape, a strip-shaped common electric wire plate 234 is sandwiched between the ceramic substrate 38. In this case, there is a slight difference in the manufacturing process from the first and second embodiments in which the common conductor layer is superimposed on the ceramic substrate, but in terms of operation and effect, the 11th and 2nd embodiments It is easy to understand that the same effects and effects as in the example can be obtained.

〔Effect of the invention〕

The present invention has been described above based on three embodiments. According to the present invention, the conventional common electrode is eliminated, a common conductor connected to the heating resistor by a three-dimensional structure is provided, and a driver electrode is used instead. The first and second rows are arranged close to each other, facing each other on both sides of the strip heating resistor, and both rows are offset in the main scanning direction, during one main scanning run of the thermal line head. Since it was possible to form two staggered rows of dots on the printing paper, the density of the dots printed on the printing paper was significantly increased. Therefore, there is an effect that high-quality prints can be obtained without incurring manufacturing difficulties or high costs.

[Brief explanation of the drawing]

1 and 2 are an enlarged plan view and a sectional view showing the characteristic configuration of a high-density thermal line head according to an embodiment of the present invention, and FIG. 3 is a thermal line head having the same characteristic configuration. 4 is a plan view showing the staggered arrangement of dots formed by the same head, and FIGS. 5 and 6 are:
FIGS. 1 and 2 show the characteristic configuration of the second embodiment of the present invention.
7 is a sectional view similar to FIG. 6 showing the configuration of the third embodiment of the present invention, and FIGS. 8 and 9 are of a conventional thermal line head. FIG. 10 is a plan view and an enlarged plan view of the main parts for explaining the structure, and FIG. 10 is an enlarged plan view of the main parts showing the structure of another conventional thermal line head. 30... Head substrate, 30a... Printing surface, 32... Heat generating resistor, 34... Common conductor layer, 36... Common wire, 38... Ceramic substrate, 40a, 40b... Driver electrodes, 42a, 42b...Driver circuit, 44...Insulating layer, 132...Heating resistor, 134...Common conductor layer, 134a...Protrusion, 234...Common electrode plate. Figure 2 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 10th port

Claims (1)

[Scope of Claims] 1. In a thermal line head that moves in a main scanning direction that intersects the paper feeding direction by a platen and transfers ink to printing paper according to heat generation control of a heating element, a thermal line head that extends in the main scanning direction A substantially central portion of the strip-shaped heating element is formed at a connection portion with a common electrode, and a first driver electrode row and a second driver electrode row are arranged and connected along both side edges of the strip-shaped heating element, and The first and second driver electrode arrays are provided with phases shifted from each other in the main scanning direction, and a staggered dot generation portion is formed between them and the heating element to increase printing density. High density thermal line head. 2. The high-density thermal line head according to claim 1, wherein the common electrode is formed of a layered body connected to the lower surface side of the band-shaped heating element. 3. The high-density thermal line head according to claim 1, wherein the first and second driver electrode arrays are arranged and connected on the upper surface of the band-shaped heating element.