JPH0848049A - Thermal printing head and production of substrate therefor - Google Patents

Abstract

PURPOSE:To reduce the power required in the printing of a thermal printing head by superposing a rectangular parallelepiped upper molded object composed of a green sheet having slits on a rectangular parallelepiped lower molded object composed of a green sheet so as to cover the slits to bake the whole. CONSTITUTION:A rectangular parallelepiped first green sheet 3 and a second green sheet 3 having almost the same dimensions as those of the sheet 3 and having a plurality of slits 4a are prepared to superpose the green sheet 4 on the green sheet 3 and the whole is held under pressure and heating to form a rectangular parallelepiped upper molded object 6 having a plurality of bottomed slits, that is, recessed parts 5 due to the slit 4a made in the surface thereof. A plurality of the green sheets 3 are stacked to be held under pressure and heating to form a rectangular parallelepiped lower molded object 7. The surface provided with the recessed parts 5 of the upper molded object 6 thus formed is superposed on the lower molded object and both molded objects are held under pressure and heating to be integrated and the whole is baked in a baking furnace to obtain a predetermined baked substrate 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal print head, and more particularly to a thermal head having improved required power characteristics and a method of manufacturing a substrate thereof.

[0002]

2. Description of the Related Art Conventionally, printers for office automation equipment such as facsimiles, printers for ticket vending machines, label printers, etc.
A thermal print head that forms necessary image information by selectively applying heat to a thermal paper is widely used. A conventional thermal print head will be described by taking a thick film type as an example. As shown in FIG. 6, a solid insulating substrate 21 made of ceramic or the like and a partial or entire surface on the surface of the insulating substrate 21. The formed glass glaze layer 22 as a heat storage body, and the common electrode 23 formed in a comb shape on the glaze layer 22 from one surface of the insulating substrate 21.
Individual electrodes 24 extending from the other side of the insulating substrate 21 toward the glaze layer 22 between the tips of the common electrodes 23, and heat generated so as to cross over the tips of the common electrodes 23 and the individual electrodes 24. And a resistor 25. Each individual electrode 24 is connected to a driving IC 26 mounted correspondingly on the insulating substrate 21 by a conductive wire 27 such as gold. A heat dissipation plate 28 made of a metal having a good heat conductivity such as aluminum is mounted on the back surface side of the insulating substrate 21.

In use of the thermal print head thus constructed, the common electrode 23 and the individual electrodes are applied by applying a predetermined voltage to the driving IC 26 while holding the common electrode 23 at a constant potential. A heat generating resistor (so-called heat generating dot) between 24 and 24 is selectively energized to form an image on the thermal paper by heating.

[0004]

However, in the conventional thermal print head, as described above, the heating resistor 25 is provided on the solid insulating substrate 21 via the glaze layer 22 or directly. Therefore, a part of the heat generated from the heating resistor 25 directly acts on the heating of the thermal paper or the like as the print medium, while the other part contributes to the heat storage of the glass glaze layer 22 as the heat storage body, It is dissipated into the atmosphere through the heat radiating plate 28 provided on the back surface side of the insulating substrate 21. As described above, since a part of the heat generated from the heating resistor 25 is inevitably used for heat dissipation, it is difficult to reduce the supplied power more than a certain amount, or to achieve sufficient energy saving. Could not be achieved.

In particular, in recent years, with the development of various OA equipment, the demand for a portable thermal printer which can be easily carried around is also increasing, and the demand for energy saving as well as the miniaturization of the thermal print head is gradually increasing. ing. Under such a situation, instead of using the glass glaze layer as described above, a heating resistor or the like is provided on the layer formed of a polyimide resin having a lower thermal conductivity to prevent the heat generated through the insulating substrate. Some attempts have been made to reduce power consumption by reducing the emission.

However, the polyimide resin has elasticity by its nature, and its mechanical strength is insufficient, and the temperature is about 500.degree.
There is a problem in reliability such as deterioration at the temperature and poor heat resistance, and it has not yet been put to practical use. Therefore, it is an object of the present invention to provide a thermal print head and a method of manufacturing the substrate for the same, in which the power required for printing is reduced.

[0007]

In order to achieve the above object, according to the present invention, there is provided a method for manufacturing a substrate for a thermal print head by laminating and firing a plurality of green sheets, which comprises a rectangular parallelepiped from the green sheets. -Shaped lower molded body and a rectangular parallelepiped upper molded body having slits formed on at least one surface were prepared, and the upper molded body was superposed so that the slits were covered on the lower molded body. A method for manufacturing a substrate for a thermal print head, characterized in that a substrate having a uniform composition and having a hollow region inside is formed by performing firing in the state.

In the above manufacturing method, a layer made of a pyrolytic resin is formed in at least one slit of the lower molded body and the upper molded body or in a region corresponding to the slit, and the lower molded body and the upper molded body are thermally decomposed. It can be carried out by firing in a state where the functional resin layer is sandwiched between the two and superposed. According to the present invention, further, an electrically insulating substrate,
A method for manufacturing a thermal printhead, comprising: common and individual electrodes formed on the substrate; and a heating resistor provided so that a heating region is formed between the common and individual electrodes adjacent to each other. A green rectangular parallelepiped lower molded body and a rectangular parallelepiped upper molded body having slits formed on at least one surface thereof are respectively prepared so that the slits are covered on the lower molded body. A thermal process, characterized in that a substrate having a uniform composition and having a hollow region inside is formed by firing the upper compacts in a stacked state, and the heating resistor is formed above the hollow region. A method of manufacturing a printhead is provided.

[0009]

[Operation and effect] Prepare a rectangular parallelepiped lower molded body and a rectangular parallelepiped upper molded body having slits formed on at least one surface from a green sheet,
Since a thermal printhead substrate with a uniform composition and a hollow region inside is formed by baking the upper compacts so that the slits are covered on the lower compacts, the heating resistor is provided. A hollow region can be easily provided in the formed substrate.

When a thermal print head is formed using such a substrate, the hollow region acts to prevent heat generated from the heating resistor from being dissipated to the outside through the region of the substrate near the heating resistor. Therefore, it is possible to form an image on the thermal paper with significantly smaller electric power than that of the conventional head. Therefore, it is possible to form a desired image with lower power, especially for a portable type battery-powered thermal print head that needs to be driven under a limited power source.

Further, in the thermal print head of the present invention, a larger dot size can be enlarged with a smaller power increase. In the production of a substrate, by forming a layer made of a thermally decomposable resin in a region corresponding to the slit of at least one of the upper molded body and the lower molded body, and by stacking both molded bodies so as to sandwich the thermally decomposable resin layer. If the substrate is formed, the pyrolyzable resin layer acts to fill the hollow region and maintain its shape before firing, and it is decomposed into a gas during firing and is released to the outside through the green sheet. A hollow region with less deformation can be reliably formed.

[0012]

Next, a method of manufacturing a thermal print head and its substrate according to the present invention will be described in detail according to an embodiment with reference to FIGS. As shown in FIG. 1, a substrate 1 for a thermal print head according to a first embodiment of the present invention has a hollow region 2 extending in the longitudinal direction of the substrate by stacking and firing a plurality of green sheets described below.
Is formed.

The composition of the green sheet as the substrate material is about 35% by weight of powdered alumina and about 3% by weight.
It is composed of 5% borosilicate glass and about 30% thermoplastic polyvinyl butyral resin. The thermoplastic resin used for the green sheet is not limited to the above-mentioned polyvinyl butyral resin, for example, a polyacrylic resin or the like, and when it is heated to a temperature of about 80 to 100 ° C., it is softened and adhesiveness is obtained. , Higher than this, for example, about 50
Any material having a property of being thermally decomposed and vaporized into a gas when heated to 0 ° C. is applicable.

In manufacturing the substrate, first, with the above-described composition, for example, the vertical and horizontal dimensions are about 130 mm and about 320 mm, and the thickness is about 0.
A flat first green sheet 3 having a size of 2 mm and a flat second green sheet 4 as shown in FIG. 2 in which a plurality of slits having substantially the same size as the slit are formed by punching by a press are prepared. To do.

When the first and second green sheets 3 and 4 are prepared in this way, as shown in FIG. 3 (a), the second green sheet 4 is superposed on the first green sheet 3, and about 200 kg / cm. ^The slit 4a is formed on the surface by keeping it heated to about 90 ° C under the pressure of ² for about 30 minutes.
To form a generally rectangular parallelepiped upper molded body 6 in which a plurality of bottomed slits, that is, concave portions 5 are defined.
As shown in (b), a plurality of first green sheets 3 are laminated to each other under a pressure of about 200 kg / cm ² to about 90
The rectangular parallelepiped lower molded body 7 is formed by holding the heated state at a temperature of ° C for about 30 minutes.

As described above, since the resin components contained in the green sheets 3 and 4 are softened when they are heated to provide the green sheets themselves with adhesiveness, they are bonded to each other by heating them under a constant pressure. It will be possible. As shown in FIG. 3 (c), the upper compact 6 thus formed is placed under a pressure of about 200 kg / cm ² with the surface having the recess 5 formed on the lower compact 7. After being kept at a temperature of 90 ° C for about 30 minutes to be integrated, the temperature is gradually raised from room temperature in a firing furnace, and the temperature is gradually raised to about 900 ° C for about 2 hours. By lowering the temperature, the baked substrate 8 as shown in FIG. 3 (d) is obtained.

The green sheets 3 and 4 shrink about 30% in the pressurizing direction and about 13% in the direction perpendicular to the length ratio in the process of firing or the like. Therefore, such shrinkage is taken into consideration. Then, the size of the green sheet, the number of stacked layers, etc. may be determined in advance according to the size of the completed substrate. Further, in the above-described embodiment, the case where the sheets of the same size are used as the first and second green sheets 3 and 4 is shown, but the present invention is not limited to this, and the thickness is different, for example. Use the first and second green sheets,
Alternatively, it goes without saying that it is possible to partially change the thickness of the first green sheet to form the upper and lower molded bodies.

In the first and second green sheets or molded bodies as described above, the resin components contained by heating contribute to mutual bonding, and after the upper and lower molded bodies are integrated with each other. By firing at a temperature higher than the heating temperature, the resin component is thermally decomposed and vaporized, and the alumina and glass components are partially crystallized, so that a physically or chemically stable fired substrate 8 is obtained. .

Next, common and individual electrodes (not shown) are patterned on the surface of the fired substrate 8 as in the conventional method.
A uniform composition is formed by forming the heating resistor 9 and the protective film for covering and protecting the electrodes, the heating resistor, etc. above each hollow region 2, and then dividing along the dividing line and performing necessary outer shape cutting. It is possible to obtain an individual substrate 1 having a hollow region 2 formed therein.

As used herein, "upper" means, as shown in FIG.
The hollow region 2 is a region R sandwiched by two-dot chain lines in FIG. In the present embodiment, the electrodes, the heating resistors and the like were formed directly on the substrate, but it goes without saying that they may be provided on the surface of the glaze layer formed wholly or partially on the substrate surface. In addition, the substrate of this embodiment is formed so that both ends of the hollow region are closed, but by providing slits continuously in the longitudinal direction of the second green sheet, one end or both ends are opened to the outside. It is also possible to form a hollow region in the.

When an individual substrate having a hollow region formed therein is obtained in this manner, a driving IC is mounted on the substrate by a method similar to the conventional one, and necessary processing such as wire bonding is performed to perform thermal printing. A head can be formed. Next, a second embodiment of the present invention will be described. In the second embodiment, a layer made of a thermally decomposable resin is formed in at least one slit of the upper molded body 6 and the lower molded body 7 or in a region corresponding to the slit, and
The second embodiment is the same as the first embodiment except that the lower molded body 7 and the lower molded body 7 are fired in a state in which the thermally decomposable resin layer is sandwiched therebetween.

When a resin layer is formed on the lower forming body 7, as shown in FIG. 5, a layer 12 made of a thermally decomposable resin is screen-printed on the surface of the lower forming body 7 in a pattern corresponding to the recesses 5. And the like, the upper molded body 6 is superposed on the lower molded body 7 and the resin layer 12 is accommodated in the concave portion 5, under the same conditions as in the first embodiment, that is, about 150 k.
Approximately 1 when heated to a temperature of approximately 90 ° C under a pressure of g / cm ^2.
After they are integrated under the condition of holding for 5 minutes, they are fired under the same conditions as in the first embodiment, that is, at the temperature of about 900 ° C. for about 2 hours, to obtain the fired substrate 8.

As the resin used for the resin layer 12, for example, a resin containing polyvinyl alcohol as a main component can be applied. The resin component is decomposed into a gas during the above-mentioned firing and the molded body 6 is formed. Since it is diffused to the outside through the meat wall and the like, a substrate having a hollow region inside can be obtained also in this embodiment as in the first embodiment.

By utilizing such a heat-decomposable resin layer when forming the hollow region 2 of the substrate 1, even when carrying out steps such as integration of the two molded bodies and firing, accurate deformation with less deformation is achieved. It becomes possible to surely form the hollow region 2 having a shape in the substrate. In addition, in the second embodiment, the resin layer 12 is formed on the lower molded body 7, but instead of this, the resin layer 12 is formed so as to fill the recess 5 of the upper molded body 6 and the lower molded body 7 is formed. You may superimpose it on and integrate and sinter.

In the above-mentioned first and second embodiments, an example is shown in which the upper compact 6 and the lower compact 7 are once formed, then they are stacked and fired to obtain the fired substrate 8. Alternatively, it is also possible to form the fired substrate 8 by heating the first green sheet 3 and the second green sheet 4 in a state of being superposed at one time, and then integrating them by heating and then firing. For such integration by heating, the pressure and heating temperature according to the formation of the molded bodies 6 and 7 in the above-mentioned embodiment can be applied, and the pressure and the firing temperature at the time of firing can be the same as those at the time of firing. It is possible to apply conditions according to the conditions.

As described above in detail, according to the manufacturing method of the present invention, the green sheet has a lower shaped body having a rectangular parallelepiped shape and an upper shaped body having a rectangular parallelepiped shape having slits formed on at least one surface thereof. Respectively, to form a thermal print head substrate having a hollow region made of a uniform composition by firing in a state where the upper molded body is superposed so that the slits are covered on the lower molded body. The hollow area can be easily provided in the substrate on which the heating resistor is provided.

When a thermal printhead is formed using such a substrate, the hollow region acts to prevent heat generated from the heating resistor from being dissipated to the outside through the region of the substrate near the heating resistor. Therefore, it is possible to form an image on the thermal paper with significantly smaller electric power than that of the conventional head. Therefore, it is possible to form a desired image with lower power, especially for a portable type battery-powered thermal print head that needs to be driven under a limited power source.

Further, in the thermal print head of the present invention, a larger dot size can be enlarged with a smaller power increase. Further, in the production of a substrate, a layer made of a heat decomposable resin is formed in a region corresponding to the slit of at least one of the upper molded body and the lower molded body, and both molded bodies are superposed so as to sandwich the thermally decomposable resin layer. When the substrate is formed by the above, the thermally decomposable resin layer fills the hollow region and retains its shape before firing, and is decomposed into a gas during firing and released to the outside through the green sheet. Therefore, the hollow region with less deformation can be reliably formed.

The processing conditions and the like shown in the above-mentioned examples are appropriately changed according to the composition of the green sheet, and
Needless to say, the size of the green sheet, the shape of the hollow region, and the like are not limited to those in the above-described embodiments, and can be appropriately changed according to the type of the thermal print head, the size of the substrate, and the like.

[Brief description of drawings]

FIG. 1 is a perspective view of a substrate according to a first embodiment.

FIG. 2 is a plan view of a second green sheet used for manufacturing the substrate of FIG.

FIG. 3 is an explanatory diagram showing a method of manufacturing the substrate of FIG.

FIG. 4 is a partial cross-sectional view showing a positional relationship between a hollow region and a heating resistor.

FIG. 5 is an explanatory diagram showing the method of manufacturing the substrate of the second embodiment.

FIG. 6 is a schematic side view of a conventional thermal print head.

[Explanation of symbols]

 1 Substrate 2 Hollow Region 3 First Green Sheet 4 Second Green Sheet 4a Slit 5 Recess 6 Upper Molded Body 7 Lower Molded Body 8 Firing Base 9 Heating Resistor 12 Resin Layer

Claims (4)

[Claims] 1. A method of manufacturing a substrate for a thermal print head by stacking and firing a plurality of green sheets, wherein a rectangular parallelepiped lower molded body and a slit opened on at least one surface are formed from the green sheets. Also, a rectangular parallelepiped upper molded body is prepared respectively, and by firing in a state where the upper molded body is superposed so that the slits are covered on the lower molded body, a uniform composition is formed inside the hollow region. A method for manufacturing a substrate for a thermal print head, which comprises forming a substrate having: 2. A layer made of a thermally decomposable resin is formed in a slit of at least one of the lower molded body and the upper molded body or in a region corresponding to the slit, and the lower molded body and the upper molded body are heated by the heat treatment. The method for manufacturing a substrate for a thermal print head according to claim 1, wherein firing is performed in a state where the decomposable resin layer is sandwiched between the two and stacked. 3. A method for manufacturing a substrate for a thermal print head by stacking and firing a plurality of green sheets, wherein a first flat green sheet and a slit which is also flat but is open on at least one side are provided. Second formed
A method for manufacturing a substrate for a thermal print head, which comprises forming a substrate having a uniform composition and having a hollow region inside by laminating green sheets and then firing the same. 4. An electrically insulating substrate, a common and individual electrode formed on the substrate, and a heat generating region formed between adjacent ones of the common and individual electrodes. A method of manufacturing a thermal print head having a heating resistor, and a rectangular parallelepiped lower molded body and a rectangular parallelepiped upper molded body having slits formed on at least one surface thereof are prepared. Then, by firing in a state in which the upper molded body is superposed so that the slits are covered on the lower molded body, a substrate having a hollow region made of a uniform composition is formed, and the substrate above the hollow region is formed. A method of manufacturing a thermal print head, characterized in that the heating resistor is formed on the substrate.