JPH08295043A - Thermal head - Google Patents

Abstract

PURPOSE: To sufficiently ensure not only the angle of inclination of a thermal head or the peel angle of an ink ribbon but also the current capacity of a common electrode and to improve the electrical continuity of the common electrode and a metal conductor layer in order to ensure the current capacity of the common electrode. CONSTITUTION: A metal conductor layer 12 and a glaze layer 13 are laminated on a substrate 11 and the glaze layer 13 is formed so as to be gradually reduced in thickness toward the end part of the metal conductor layer 12 on one end side thereof and the processing of the groove cutting the glaze layer 13 and the metal conductor layer 12 and reaching the interior of the substrate 11 is applied at a position where the thickness of the glaze layer 13 on the metal conductor layer 12 becomes 5-15μm. A common electrode 16 is formed to the cut surface part of the metal conductor layer 12 accompanied by the groove processing in an electrical continuity state and a heating part 18 is formed in the vicinity of the groove processing position becoming the end surface part of the substrate 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head used for thermal printers, facsimiles and the like.

[0002]

2. Description of the Related Art Conventionally, thermal printers using a thermal head include those that use thermal paper, those that thermally transfer ink to plain paper using an ink ribbon, and those that record with ink vapor using a sublimable dye. There are things to do.

Nowadays, many of these thermal heads employ an end surface type thermal head in which a heat generating portion is arranged on an end surface portion of a substrate. According to such an end surface type thermal head, the pressing force of the thermal head is concentrated on the heat generating portion, so that the printing quality is improved as compared with the flat type thermal head. In particular, when the glaze layer formed as the heat storage layer on the substrate is a partial glaze having a predetermined curvature, the pressing force of the thermal head is further concentrated on the heat generating portion, and the printing quality is further improved.

Further, when such a partial glaze is adopted, since a straight pass is possible, printing is performed not only on flexible paper such as plain paper but also on a hard card that cannot be folded. You can

Further, when an ink ribbon is used, the peeling distance of the ribbon can be shortened and the peeling angle can be increased by adopting the partial glaze, so that the transfer of ink is improved and the printing quality is improved. .

However, in the end surface type thermal head, since the heat generating portion is located at the end portion of the substrate, the space for providing the common electrode is narrowed and it is difficult to secure a sufficient current capacity. If a sufficient current capacity cannot be secured, a voltage drop phenomenon will occur during simultaneous energization of multiple dots,
The print density decreases.

Therefore, in the conventional end surface type thermal head, the current capacity of the common electrode is ensured by adopting the structure shown in FIGS. 9 to 12.

First, in the thermal head shown in FIG. 9, a partial glaze 2 is formed on an end of an insulating substrate 1, and further,
The heating resistor layer 3, the individual electrode 4, the common electrode 5, and the protective film 6 are formed, and the heating portion 7 is formed between the individual electrode 4 and the common electrode 5 in the heating resistor layer 3. The common electrode 5 is wired on the back surface of the substrate 1 to secure the current capacity.

The thermal head shown in FIG. 10 secures current capacity by wiring the common electrode 5 to the same side as the individual electrodes 4. It should be noted that one dot is formed by the two heat generating portions 8a and 8b.

The thermal head shown in FIG.
A metal conductor layer 9 is formed between the metal glaze 2 and the partial glaze 2, and the common electrode 5 and the metal conductor layer 9 are electrically connected to each other to secure a current capacity.

The thermal head shown in FIG. 12 is similar to that shown in FIG.
This is an improved type of the thermal head shown in FIG. 1 and is disclosed in JP-A-2-286260. The chamfered portion 10 is formed at the end of the substrate 1, and the metal conductor layer 9 and the common electrode 5 are formed using the surface of the chamfered portion 10.

[0012]

SUMMARY OF THE INVENTION A method of manufacturing a thermal head is to provide a substrate having a size substantially the same as a size in which the substrates 1 of the thermal heads for a plurality of units are integrated, and to mount a plurality of thermal heads on the substrate. Is generally formed, and finally this substrate is divided into each thermal head unit. However, in the thermal head shown in FIG. 9, the common electrode 5, the protective film 6 and the like must be formed after dividing the substrate into units of each thermal head, which reduces the mass productivity and increases the manufacturing cost.

In the thermal head shown in FIG. 10, the total number of wirings between the common electrode 5 and the individual electrode 4 is 1.5 times that of other thermal heads, and the structure is complicated.

In the thermal head shown in FIG. 11, the width dimension "L" from the end of the partial glaze 2 on the common electrode side to the end of the substrate 1 is 50 to 100 μm. The peeling angle cannot be set large.

In the thermal head shown in FIG. 12, the chamfered portion 10 is formed by forming V-shaped grooves in advance on one substrate forming a plurality of thermal heads, and the chamfered portion 10 becomes an inclined surface of the V-shaped grooves. Since the metal conductor layer 9 is formed by screen-printing the metal paste on the chamfered portion 10 and firing it, the angle of the V-shaped groove cannot be set very large. The peeling angle of 1 is larger than that of the thermal head of FIG. 11, but is not sufficiently large.

Also, as is common to each thermal head, since the partial glaze 2 is formed by screen-printing a paste-like material and firing it, the end of this partial glaze 2 has some undulations. , Cannot be formed in a perfect straight line. The waviness at the end of the partial glaze 2 adversely affects the pressing force of the thermal head and the uniformity of the ink ribbon peeling property. In the thermal head shown in FIGS. 9 and 10, the waviness of the partial glaze 2 can be eliminated by cutting or polishing the partial glaze 2. However, in the thermal head shown in FIGS. Since the metal conductor layer 9 is formed on the lower side, the partial glaze 2 cannot be cut or polished without adversely affecting the metal conductor layer 9.

Therefore, according to the present invention, the current capacity of the common electrode can be secured, the thermal head inclination angle and the ink ribbon peeling angle can be secured at the same time, and the waviness at the end of the glaze layer can be eliminated to improve the printing quality. Provided is an end face type thermal head which further stabilizes.

[0018]

According to the present invention, a metal conductor layer and a glaze layer are laminated on an insulating substrate, and a heating resistor layer, a common electrode, an individual electrode and a protective film are formed on the glaze layer. In the formed thermal head, one end side of the glaze layer located on the metal conductor layer is formed in a shape in which the film thickness gradually decreases toward the end of the metal conductor layer, and the glaze on the metal conductor layer is formed. Layer thickness is 5-15μ
At the position of m, the glaze layer and the metal conductor layer are cut and a groove is formed to reach the inside of the substrate to expose the cut surface portion of the metal conductor layer, and the cut surface portion of the metal conductor layer is electrically cut. To form the common electrode, and a heat generating portion was formed in the vicinity of a groove processing position which is an end face portion of the substrate.

[0019]

In the present invention, the metal conductor layer and the glaze layer laminated on the substrate are cut and the groove surface reaching the inside of the substrate is processed to expose the cut surface portion of the metal conductor layer. By forming the common electrode, an electrical conduction state between the metal conductor layer and the common electrode can be easily obtained, and a sufficient current capacity of the common electrode can be secured. Then, by forming the groove processing position on the end face portion of the substrate and forming the heat generating portion near the end face portion,
It is possible to secure a sufficiently large inclination angle of the thermal head and a peeling angle of the ink ribbon. Further, one end side of the glaze layer located on the metal conductor layer is formed in a shape in which the film thickness gradually decreases toward the end portion of the metal conductor layer, and the film thickness of the glaze layer on the metal conductor layer is 5 to 15 μm. By grooving at the positions to be formed, chipping of the glaze layer and curling up of the metal conductor layer due to the groove machining do not occur, and when the common electrode is formed, the common electrode and the metal conductor layer Good electrical continuity. Further, by grooving, the waviness at the end of the glaze layer is eliminated, and it is possible to prevent deterioration of the print quality due to this waviness.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention including a manufacturing process will be described with reference to FIGS. FIG. 1 is a vertical sectional side view showing a completed thermal head. A metal conductor layer 12 made of Au or the like having good conductivity is formed on an end portion of an insulating substrate 11 formed of alumina or the like.
Is covered with a partial glaze 13 which is a glaze layer. Further, the heating resistor layer 14, the individual electrode 15, the common electrode 16, and the protective film 17 are formed on the partial glaze 13 and the upper surface of the substrate 11 to form the heating resistor layer 1.
The heat generating portion 18 is formed in the portion between the individual electrode 15 and the common electrode 16 in FIG.

2 and 3 show a part of the manufacturing process. First, as shown in FIG. 2, a plurality of (in this embodiment, 4
A substrate 19 of substantially the same size as the integrated size of the thermal head substrates 11 is provided, and four metal conductor layers 12 and four partial glazes 13 and 2 are provided on the upper surface of the substrate 19.
The individual bonding pad glaze 20 is formed.
The metal conductor layer 12 is formed by printing a conductive paste such as Au on the surface of the substrate 11 and firing it. Further, the partial glaze 13 is formed so that the cross-sectional shape in the direction orthogonal to its longitudinal direction becomes a dome shape, and the film thickness thereof is gradually reduced toward the end of the metal conductor layer 12. Then, the substrate 19 is finally divided along the broken line "A" and a groove described later to manufacture four thermal heads.

Next, after forming the metal conductor layer 12 and the partial glaze 13 on the substrate 19, a groove is formed at a position indicated by an arrow "B" in FIG. 2 using a dicer. This groove processing is performed so that the partial glaze 13 and the metal conductor layer 12 are cut and the groove 21 reaches the inside of the substrate 19, as shown in FIG. The groove processing is performed at a position where the film thickness of the partial glaze 13 is 5 to 15 μm.

By performing this groove processing, the cut surface portion of the metal conductor layer 12 is exposed and the end portion along the longitudinal direction of the partial glaze 13 is made straight. After the groove processing, the heating resistor layer 14 containing an oxide such as ruthenium oxide is formed on the entire surface of the substrate 19 including the upper surface of the partial glaze 13 and the inside of the groove 21 to a thickness of 1000 Å by a sputtering method. Film uniformly. The heating resistor layer 14 is stabilized by annealing at 650 ° C. for 1 hour after the film formation is completed.

Then, the titanium-containing nitride T
Bottom layer composed of iN (titanium nitride) (layer thickness 1000Å)
And Al which is an aluminum alloy containing silicon and copper
-Si-Cu (copper-silicon-aluminum alloy) intermediate layer (layer thickness 3000 Å) and aluminum uppermost layer (layer thickness 7000 Å) are sequentially formed on the heating resistor layer 14 by a sputtering method. Then, these are patterned into a predetermined shape by photolithography to form the individual electrode 15 and the common electrode 16 having a three-layer structure. The heat generating portion 18 formed between the individual electrode 15 and the common electrode 16 is arranged in the vicinity of the position where the groove 21 is formed, and has a predetermined inclination angle (thermal head) with respect to the surface of the substrate 11. The inclination angle) was obtained.

In this way, the individual electrode 15 and the common electrode 1
6 and the heating portion 18 are formed, then 3Al ₂ O ₃ .2Si is formed.
A first protective layer made of O ₂ (mullite) or the like and a second protective layer made of SiC (silicon carbide) or the like are sequentially formed by a sputtering method to form the protective film 17 having a two-layer structure. The film 17 covers the electrodes 15, 16 and the heating portion 18 entirely. Then, the substrate 19 is divided from the groove 21 and the central portion of the bonding pad glaze 20 shown by the broken line "A" in FIG. 2 to manufacture a thermal head as shown in FIG.

In this structure, the thermal head applies a predetermined driving voltage between the individual electrode 15 and the common electrode 16 to selectively heat the desired heat generating portion 18 to drive the dot matrix. It is designed to print images in the format.

Next, in this thermal head, the metal conductor layer 12 and the partial glaze 13 are cut and groove processing is performed to expose the cut surface portion of the metal conductor layer 12, and then the heating resistor layer 14 and the common electrode 16 are formed. Forming a common electrode 1
6 faces the metal conductor layer 12 with the heating resistor layer 14 in between. Here, the thickness dimension of the cut surface portion of the metal conductor layer 12 is set to 1
0 μm, the thickness of the heating resistor layer 14 is 1000 Å, and the dimension of the heating portion 18 is L × L μm, the resistance value between the common electrode 16 and the metal conductor layer 12 is smaller than the resistance value of the heating portion 18. Is 1/1000 L, which is a value that can be sufficiently ignored. Therefore, the common electrode 16 and the metal conductor layer 12 are electrically connected to each other, and even if the width dimension (the dimension from the end portion of the substrate 11 to the heat generating portion 18) for arranging the common electrode 16 is reduced, The current capacity of the common electrode 16 can be sufficiently secured.

By providing the heat generating portion 18 at the end portion of the substrate 11 as described above, the heat generating portion 18 is provided.
The inclination angle of the substrate 11 with respect to the surface of the substrate 11 (thermal head inclination angle) can be increased, and when an ink ribbon is used, the peeling angle of the ink ribbon can be sufficiently increased.

Next, various thermal heads were manufactured by changing the position of forming the groove 21 (distance from the end of the partial glaze 13 to the groove 21), and the film thickness of the partial glaze 13 at the cut portion of each thermal head. , Metal conductor layer 12
The cut surface state, the partial glaze 13 chipping state, the connection state between the common electrode 16 and the metal conductor layer 12, and the like were observed.

In the thermal head prototyped for this test, the thickness of the substrate 11 made of alumina was 1 mm,
The thickness of the metal conductor layer 12 made of Au is 10 μm, the width of the partial glaze 13 is 1 mm, and the thickness at the center is 38 μm.
The shape of the groove 21 is 200 μm and the dimension from the bottom surface of the substrate 11 is 0.5 mm. Then, in these two types of thermal heads, the formation positions of the grooves 21 were set to seven positions from the end portion to the central portion of the partial glaze 13.

Further, in the case of inspecting the connection state between the common electrode 16 and the metal conductor layer 12 in each of the thermal heads in which seven positions for forming the groove 21 are set, as shown in FIG. 4 (a), The common electrode 16 was patterned so as to be connected to the metal conductor layer 12 in a separated state without being integrated. Further, when manufacturing a thermal head as a product, as shown in FIG. 4B, the common electrodes 16 were patterned so as to be continuous with each other. The test results are shown in Table 1.

[0032]

[Table 1]

According to the test results shown in Table 1, the chipping tends to increase as the thickness of the partial glaze 13 cut for forming the groove 21 increases toward the central portion. When the film thickness of the partial glaze 13 was up to about 15 μm, chipping hardly occurred and it was good.

Regarding the state of the cut surface of the metal conductor layer 12,
In the place where the groove 21 was formed, where the partial glaze 13 was extremely thin, a portion where the metal conductor layer 12 was turned up from the cut surface was observed. The turned-up portion of the metal conductor layer 12 did not drop even if it was scrubbed or ultrasonically cleaned. If the cut surface is turned up and is defective, the ink ribbon comes into contact with the turned-up portion and rubs during printing, and the protective film 17 is peeled off from the turned-up portion. There was a problem of reduced durability.

Regarding the evaluation of the connection state between the common electrode 16 and the metal conductor layer 12, "O" is a defect rate of less than 5%, "O".
Was determined as a defective rate of less than 10% and “X” was a defective rate of 10% or more. However, the result of chipping was reflected as it was, and it was better to form the groove 21 in the portion where the partial glaze 13 was thin. Was given.

On the other hand, regarding the thermal head in which the partial glaze 13 hardly chipped and the metal conductor layer 12 had a good cut surface condition, there was no uneven density, good print quality, and no problem with durability. Therefore, from the above test results, it was found that by performing groove processing at the position where the film thickness of the partial glaze 13 is 5 to 15 μm, a durable thermal head with excellent printing quality can be obtained.

Further, by carrying out such groove processing, it is possible to eliminate the waviness of the end portion of the partial glaze 13 which occurs when forming the partial glaze 13 and to align the end portions of the partial glaze 13 in a straight line. As a result, the pressing force of the head becomes substantially uniform in each heat generating portion 18, and the peeled state of the ink ribbon does not partially vary, so that uneven density does not occur and the print quality becomes stable.

Further, the individual electrode 1 is formed on one substrate 19.
Since a plurality of thermal heads are completed by dividing the substrate 19 from a predetermined position after forming all of 5, 5, the common electrode 16, the protective film 17, etc., the thermal head of the conventional example shown in FIG. When compared, mass productivity can be improved and manufacturing cost can be reduced.

Next, the inventor of the present application has made the metal conductor layer 1
When a thermal head with the film thickness of 2 changed to 5 μm, 20 μm, and 50 μm (other conditions are the same as the prototype) was prototyped and the same test as above was performed, the same result as above was obtained. Was given.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the groove 21a is formed in a wedge shape, and other configurations are the same as those of the thermal head shown in FIGS. When the above-described test was performed on the thermal head having such a wedge-shaped groove 21a, similar results were obtained.

Next, a third embodiment of the present invention will be described with reference to FIG. In this embodiment, the groove 21b is formed in a V-shape, and other configurations are the same as those of the thermal head shown in FIGS. When the above-described test was performed on the thermal head having such a V-shaped groove 21b, similar results were obtained.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. 7 and 8. In this embodiment, the metal conductor layer 12
The flat glaze 22 is formed as a glaze layer covering the. The plane glaze 22 is a combination of the partial glaze 13 described with reference to FIGS. 1 to 4 and the bonding pad glaze 20. Note that the end of the flat glaze 22 on the side where the groove 21 is formed is formed so that the film thickness gradually decreases toward the end of the metal conductor layer 12 in the curved state, similarly to the partial glaze 13 described above. When the above-described test was performed on the thermal head of this example, similar results were obtained. Further, in the case of the present embodiment, the width dimension of the metal conductor layer 12 can be made larger than that of the thermal head in which the partial glaze 13 is formed, and by increasing the width dimension of the metal conductor layer 12,
It becomes easier to secure the current capacity of the common electrode 16.

[0043]

According to the present invention, the groove processing is performed at the position where the thickness of the glaze layer is 5 to 15 μm on the metal conductor layer, so that the chipping of the glaze layer accompanying the groove processing and the metal conductor layer It is possible to prevent the curling up, so that the electric conduction between the common electrode and the metal conductor layer can be ensured and the current capacity of the common electrode can be sufficiently secured. By locating it at the edge of the substrate, the thermal head inclination angle and the ink ribbon peeling angle can be sufficiently secured, and groove processing can eliminate the undulation at the edge of the glaze layer, so this undulation It is possible to prevent the unevenness of the pressing force of the head and the peeling property of the ink ribbon, which are the causes, and improve the image quality.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a first embodiment of the present invention.

FIG. 2 is a plan view showing a state in which a metal conductor layer, a partial glaze and a bonding pad glaze are laminated on a substrate.

FIG. 3 is a vertical cross-sectional side view illustrating a state in which a substrate is grooved.

4A and 4B show prototypes of thermal heads for various tests, where FIG. 4A is a front view showing a patterning state for performing a connection state test between a common electrode and a metal conductor layer; FIG. 8] is a front view showing a wiring state on the common electrode side when a printing test is performed.

FIG. 5 is a vertical sectional side view showing a second embodiment of the present invention.

FIG. 6 is a vertical sectional side view showing a third embodiment of the present invention.

FIG. 7 is a vertical sectional side view showing a fourth embodiment of the present invention.

FIG. 8 is a plan view showing a state in which a metal conductor layer and a plane glaze are laminated on a substrate.

FIG. 9 is a vertical sectional side view showing a first conventional thermal head.

FIG. 10 is a plan view showing a second conventional thermal head.

FIG. 11 is a vertical sectional side view showing a thermal head of a third conventional example.

FIG. 12 is a vertical sectional side view showing a thermal head of a fourth conventional example.

[Explanation of symbols]

 11 substrate 12 metal conductor layer 13, 22 glaze layer 14 heating resistor layer 15 individual electrode 16 common electrode 17 protective film 18 heating portion 21, 21a, 21b groove

Claims (1)

[Claims] 1. A thermal head in which a metal conductor layer and a glaze layer are laminated on an insulating substrate, and a heating resistor layer, a common electrode, an individual electrode, and a protective film are formed on the glaze layer. One end side of the glaze layer located on the conductor layer is formed in a shape in which the film thickness gradually decreases toward the end of the metal conductor layer, and the film thickness of the glaze layer on the metal conductor layer is 5 to 15 μm. To cut the glaze layer and the metal conductor layer at a position to expose the cut surface portion of the metal conductor layer by performing groove processing reaching the inside of the substrate, and electrically to the cut surface portion of the metal conductor layer. The thermal head is characterized in that the common electrode is formed by conduction and a heat generating portion is formed in the vicinity of a groove processing position which is an end surface portion of the substrate.