JP2886717B2 - Edge type thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end face type thermal head suitably used for a thermal type or thermal transfer type printer, facsimile or the like.

[0002]

2. Description of the Related Art Conventionally, as a thermal head used for a printer, a facsimile or the like, a flat thermal head in which a portion provided with a driver IC for driving and a heating resistor portion are provided on the same main plane of a substrate, JP-A-60-80
No. 81, Japanese Unexamined Patent Publication No. 61-40168, etc., an end-face type thermal head having a heating resistor provided on an end face of a substrate has been put to practical use.

[0003] In particular, the end-face type thermal head has better contact properties of the heat-generating resistor portion with the thermal paper or film as compared with the flat-type thermal head, and has an escape for avoiding contact between the drive circuit and the platen. It has been recognized that there is no need to provide, and it is more advantageous as it has various advantages such as easy miniaturization of the entire device and easy securing of the flatness of the portion where the heating resistor is provided. .

However, in such an end face type thermal head, in order to improve the recording quality of printing or printing, the distance between the recording electrode for electrically connecting the heating resistor and the return electrode is made uniform. When the substrate located between the electrodes is made of a thin plate that can meet such demands, it is extremely difficult to handle such a thin plate during head manufacturing. It is difficult and the mechanical strength cannot be sufficiently secured. Furthermore, in such a conventional end-face type thermal head, it is difficult to perform high-precision processing of an end face of a substrate on which a predetermined heating resistor is formed, and the thermal characteristics of the heating resistor are improved to perform patterning. As shown in FIG.
The glaze layer 6 is formed on the surface on which the heating resistor 4 is formed. However, it is difficult to uniformly form the glaze layer 6 on such an end face, and further, the thermal characteristics due to the formation of the glaze layer 6 are reduced. In the adjustment, there are many restrictions on the shape of the substrate and the shape of the glaze, and there are inherent problems such as a low degree of freedom in thermal design. Furthermore, such a conventional end-face type thermal head employs a structure in which the heat generating resistance portion (4) projects from the base 8 supporting the entire head toward the thermal paper or film. In many cases, it is difficult to quickly radiate heat to the base 8 or the like after using the heat generated in the heat generating resistor portion (4) for printing, so that dot blur, tailing, etc. occur, and the recording quality is sufficiently good. It was not something. In FIG. 1, 10 is a recording electrode, 12 is a return electrode, and 14 is a protective layer.

[0005]

The present invention has been completed in view of the above-mentioned circumstances, and the problem to be solved is to provide excellent heat response, high recording sensitivity, and high speed printing. It is an object of the present invention to provide an end-face type thermal head having good recording quality even during shooting.

[0006]

According to the present invention, in order to solve the above-mentioned problem, at least the tip portion of the ceramic substrate is made thin, a heating resistor is provided in the thin portion, and the heating resistor is energized. In the end face type thermal head in which the recording electrode and the return electrode for performing the above are respectively supported by the ceramic substrate, at least at the front end of the ceramic substrate, and close to the heating resistor, While providing a radiator, the ceramic substrate has a lower thermal conductivity than the radiator, and the value of the thermal conductivity is 0.002 cal · cm / sec · cm ² · ° C.
As described above, the gist of the present invention is an end-face type thermal head characterized by being formed of a material having a temperature of 0.03 cal · cm / sec · cm ² · ° C or less.

In the end face type thermal head according to the present invention, the radiator preferably has a higher thermal conductivity than the ceramic substrate, and has a thermal conductivity of 0.01. and thus it is composed of ^{cal · cm / sec · cm 2} · ℃ higher than that material.

Further, according to the present invention, at least the tip portion of the ceramic substrate is made thin, a heating resistor is provided in the thin portion, and a recording electrode and a return electrode for supplying electricity to the heating resistor are respectively provided. In an end face type thermal head supported by the ceramic substrate, a heat radiator is provided so as to be located at least at a front end portion of the ceramic substrate and close to the heating resistor.
The radiator has a thermal conductivity higher than that of the ceramic substrate, and a value of the thermal conductivity is 0.01 cal · cm / sec.
The gist of the present invention is also an end-face type thermal head characterized in that it is made of a material having a temperature of not less than cm ² · ° C.

In thermal transfer recording, it is necessary to precisely control the thermal characteristics of the head end, that is, the heat storage property, in order to effectively use the heat generated in the heating resistor at the end of the head for transfer. However,
In conventional thermal heads, when a material such as alumina or metal having relatively high thermal conductivity is used as the substrate, the heat storage is low, so the heat generated by the heating resistor is sufficiently used for transfer. It spread without getting. Further, as shown in the example of the conventional thermal head shown in the figure, in the configuration in which the glass glaze layer 6 is formed on the substrate 2 to secure the heat storage property, the cost is increased, or the material of the glaze layer is increased. There are many restrictions on the shape, forming method,
Free thermal design was difficult. Furthermore, in the example of the conventional thermal head, there is one that uses a cylindrical glass rod as an end substrate, but in such a thermal head, since the heat storage property of the glass is too high, The printing quality was degraded.

Therefore, the substrate supporting the heating resistor has a lower thermal conductivity than a material such as alumina or metal having a relatively high thermal conductivity and a higher value than a glass having a relatively low thermal conductivity. The above problem can be solved by forming the material. In addition, by forming a target substrate using a material having such a thermal conductivity, it is not necessary to form a glaze layer, thereby reducing costs.

Further, by forming the substrate using the material having the above-described thermal conductivity, the shape of the substrate itself,
That is, it is possible to control the heat storage property of the head end portion by freely changing the volume, thereby improving the degree of freedom in designing thermal characteristics.

Further, the tip of the substrate is made thin,
A radiator made of a material having a relatively high thermal conductivity is installed at a position close to the heating resistor, and by defining the thermal conductivity of the radiator, heat generated in the heating resistor can be transferred. After effective use, the heat is quickly diffused to the head base side, so that high-quality printing without blur, bleeding, tailing, etc. of the printing dots can be obtained. In particular, such an improvement in the heat radiation characteristics works effectively at the time of high-speed printing.

[0013]

[Specific Configurations / Examples] In order to clarify the present invention more specifically, specific configurations of the present invention will be described in detail with reference to examples.

First, FIGS. 2 and 3 and FIGS. 4 and 5 show different examples of the end face type thermal head according to the present invention. In these figures, the ceramic substrate 2
Numeral 0 is formed by using a predetermined material so that at least the leading end thereof is thin, and a large number of stripe-shaped recording electrodes 22 are provided on one main plane, and the other main plane is provided. A return electrode 24 in the form of a sheet is provided on the flat surface corresponding to the shape of the surface.
4 are supported on the ceramic substrate 20, respectively. A heating resistor 26 is provided on the end surface of the thin front end portion of the ceramic substrate 20 so as to be electrically connected to the recording electrode 22 and the return electrode 24. Furthermore,
Outside the main plane of the ceramic substrate 20 that supports the return electrode 24, a radiator 28 is attached to the adhesive 3 so as to be located at least at the head end and close to the heating resistor 26.
0, so that the head structure is integrated.

In particular, in the head tip structure shown in FIGS. 2 and 3, the tip is thinned by an inclined surface extending from one main plane of the ceramic substrate 20 to the other main plane. The radiator 28 is provided so as to be positioned at least on the inclined surface, and the distal end surface is inclined so as to be at an acute angle with respect to the extension surface of the other main plane. The heating resistor 26 is provided on the surface. Then, a protective layer 32 having a predetermined thickness is provided so as to cover the head end surface on which the heating resistor 26 is provided.

In the end face type thermal head shown in FIGS. 4 and 5, one main plane and the end face of the ceramic substrate 20 having a tip thin portion extending at a predetermined thickness in front of the inclined surface similar to the previous example are provided. A glaze layer 34 is provided,
The recording electrode 22 is provided on one main plane, and the return electrode 24 is provided on another main plane facing the recording electrode 22. Further, the ceramic substrate 20 is electrically connected to the recording electrode 22 and the return electrode 24.
A heating resistor 26 is formed on the end face of the head, a heat radiator 28 is provided outside the return electrode 24 at the head tip, and a mechanical strength at the tip of the head is provided outside the recording electrode 22, Reinforcing members 36 are attached to each other with an adhesive 30 interposed therebetween. Also in this example, a protective layer 32 having a predetermined thickness is provided so as to cover the head end surface.

In such an end-face type thermal head, the ceramic substrate 20 must be formed so that at least the head end portion is thin as shown in the figure. As shown in FIGS. 4A and 4B, even when the tip end surface is the thinnest, as shown in FIGS. 4 and 5, the portion having the smallest thickness of the substrate extends over a predetermined distance from the tip end toward the substrate base side. Even if the shape is continuous, there is no problem. FIG. 2,
In the thinned structure as shown in FIG. 3, the mechanical strength at the head end can be sufficiently secured, and the pressure of the head against the film or the thermal paper can be sufficiently increased. Further, in the thinned structure as shown in FIGS. 4 and 5, the surface from the thick portion to the thin portion at the front end of the substrate 20 is formed as an obtuse inclined surface. The surface may be provided at right angles, or even may be provided in a round shape.

The width of the portion of the ceramic substrate 20 where the heating resistor 26 is formed (thickness of the front end of the substrate):
d is appropriately selected according to the printing or printing characteristics required at the head end portion, but in the present invention, d is about 10 to 400 μm, preferably 20 to 10 μm.
About 0 μm is suitably adopted. That is, if the width is 10
If the thickness is smaller than μm, the width of the heating resistor 26 becomes narrow, and a good-quality dot shape cannot be obtained. If the thickness is larger than 400 μm, a problem of heat storage in the heating resistor portion occurs. In order to obtain, it is desirable to set the width in the above range.

The thermal conductivity of the ceramic substrate 20 in the thermal head having such a structure is lower than that of the heat radiator 28, and is 0.002 cal.
・ Cm / sec ・ cm ²・ ℃ or more, 0.03 cal ・ cm / sec ・
cm ² · ° C or less, preferably 0.002 cal · cm / sec
· Cm ² · ° C. or more, which consists of 0.01 cal · cm / sec · cm 2 · ℃ or less material, more preferably, one having a value of such a thermal conductivity, per unit volume It is made of a material having a heat capacity of 0.55 cal / ° C. · cm ³ or less. In other words, by using a material having such a value of the thermophysical property, control of the thermal characteristics of the head end portion can be advantageously realized. In addition, as the substrate 20 giving such characteristics, specifically, a glass ceramic substrate, a free-cutting glass ceramic substrate, a free-cutting glass ceramic substrate containing mica, and the like are mentioned. The selection is made in consideration of the thermal conductivity of the body 28. In particular, a free-cutting glass ceramic substrate containing mica is advantageously used.

That is, since the ceramic substrate 20 has a thin end as described above, when the ceramic substrate 20 is used for various recording methods via the heating resistor 26, the heating resistor 26 becomes a film or the like. It is efficiently pressed against the thermal paper, and the contact property is remarkably improved. On the other hand, in order to efficiently concentrate the generated heat on a necessary portion, the ceramic substrate 20 needs to have an appropriate heat storage property. From the necessity, the heat storage property is not so small as alumina and aluminum nitride having relatively high heat conductivity, the heat storage property is not so high as glass having relatively low heat conductivity, and the heat generated in the heating resistor 26 is small. Is effectively used for printing, the temperature of the ceramic substrate 20 rises quickly, that is, the heat capacity per unit volume is smaller than that of alumina or metal. Machinable glass ceramic containing squid is than preferably used, good exothermic response is obtained Te following is the more may achieved also improved recording quality. Moreover, as shown in FIGS. 2 to 5, when machining is performed so that only a predetermined portion of the head end portion is thinned,
The free-cutting glass-ceramic substrate containing such mica is excellent in machinability, and can therefore easily form a high-precision thin-walled portion.

As described above, a free-cutting glass-ceramic substrate suitable for heat storage and capable of easily obtaining a high-precision substrate surface by machining is used as the ceramic substrate 20. Heating resistor 2
It is no longer necessary to provide a glaze layer that was inevitably provided between the device and the device 6, and the cost can be advantageously reduced.
Furthermore, the advantage that the problem of shortening the service life of the heating resistor 26 due to the reaction between the heating resistor 26 and the glaze layer can be avoided is also exerted.

Further, in the thermal head having such a structure, a predetermined radiator 28 is provided so as to be located at least at the end of the ceramic substrate 20 and to be close to the heating resistor 26. The heat radiator 28 is advantageously made of a material having a thermal conductivity higher than that of the ceramic substrate 20 and a thermal conductivity of 0.01 cal · cm / sec · cm ² · ° C or more. As described above, by disposing the heat radiator 28 having a specific thermal conductivity close to and close to the heat generating resistor 26, the heat radiating characteristics of the heat generating resistor 26 are improved, and therefore, a good heat-dissipation without dot blur, tailing, etc. is obtained. The recording quality can be obtained. The radiator 28 having the specific thermal conductivity exhibits a particularly excellent effect when used together with the ceramic substrate 20 having the specific thermal conductivity described above. Instead, the effect of the present invention can be sufficiently enjoyed only by considering such thermal conductivity of the heat radiator 28.

The material constituting the heat radiator 28 is, more specifically, a material such as free-cutting alumina, free-cutting boron nitride, free-cutting aluminum nitride, brass, copper, aluminum, bronze, or the like. It is preferably selected and adopted from materials containing the selected material as a main component or materials obtained by combining them. Among them, free-cutting alumina, free-cutting boron nitride, free-cutting aluminum nitride, etc. Is preferably used because it is excellent in the slidability and contact properties of the head. Further, it is desirable that the heat radiator 28 provided in the vicinity of the heating resistor 26 be slid directly on the thermal paper or film in order to improve the heat radiation.

Further, in the thermal head having such a structure, as shown in FIGS. 4 and 5, the ceramic substrate 20 is preferably provided at least on the thin portion at the head end where the heating resistor 26 is provided. On one side of the main plane of the head, a predetermined reinforcing material 36 is adhered via an adhesive 30 so as to conform to the shape of the substrate at the head end portion so as to reinforce at least the thin thick portion at the head end portion. . The reinforcing member 36 is preferably a recording electrode 2
2 and the heat generating resistor 2 having a lower hardness than the return electrode 24.
In the case where a material that is more wear-resistant than 6, or a protective layer 32 is provided, a material that is more easily wearable will be used, and in particular, the Knoop hardness is 1000 kgf / mm ^2.
Hereinafter, more preferably, materials such as metals, ceramics, glass, and glass ceramics of 500 kgf / mm ² or less are appropriately selected and used. As a result, the heating resistor 26 provided on the end face of the substrate 20 has a shape slightly protruding forward from the end face of the reinforcing member 36 while sliding with the thermal paper or film, and both the mechanical strength and the contact property are improved. You can be satisfied.

More specifically, as the easily wearable material constituting the reinforcing member 36, a free-cutting glass ceramic, a free-cutting glass ceramic containing mica, a free-cutting alumina, and a free-cutting boron nitride are used. A material mainly composed of a material selected from aluminum nitride, brass, copper, aluminum, bronze, and the like, or a material obtained by combining them is preferably employed. Among them, a free-cutting glass ceramic containing mica is preferable. A material mainly containing free-cutting alumina, free-cutting boron nitride, free-cutting aluminum nitride, or the like is preferably used because it has excellent slidability and contact properties of the head. In particular, free-cutting alumina, free-cutting boron nitride,
Since the material mainly containing free-cutting aluminum nitride or the like is excellent in thermal conductivity, it also has the role of the above-mentioned heat radiator 28, and the reinforcing material 36 made of such an easily wearable material is provided. Thereby, the heat radiation characteristics can be further improved.

As described above, in the above-described thermal head structure, by arranging the predetermined reinforcing member 36 at least at the front end of the head, when the thermal head is used, the reinforcing member 36 can be connected to the thermal paper or film. The exfoliation or the like of the heating resistor 26 or the protective layer 32 due to the sliding contact is not caused, and the exfoliated material or the like is caught between the electrode and the thermal paper or the like, which may cause a problem of obstructing printing or printing. In terms of the absence, etc., excellent characteristics are exhibited.

The radiator 28 and the reinforcing member 36 as illustrated
Adhesive 3 for adhering to main surface of ceramic substrate 20
As 0, even if an inorganic material containing alumina, silica, boron nitride, or the like, or a resin material containing epoxy, phenol, polyimide, or the like is used, a composite containing the inorganic material and the resin material is used. Materials may be used,
Among them, inorganic materials including alumina, silica, boron nitride and the like are preferably selected.

Further, according to the present invention, as illustrated,
To protect the heating resistor 26 and the electrodes 22, 24, etc.
If necessary, a suitable insulating material, for example silicon oxide,
Using a material appropriately selected from silicon nitride, silicon carbide, tantalum oxide, glass, and the like, it is also possible to provide the protective layer 32 at least at the tip of the head. Wear, insulation coating, and the like can be effectively achieved. Note that this protective layer 32
Is provided according to a known method such as sputtering, CVD, and a thick film method, and may be not only a single-layer structure selected from the above materials, but also a multilayer structure made of the above materials, When used for insulation coating of such leads, organic materials such as epoxy, phenol, and polyimide are advantageously used.

Further, in the end face type thermal head according to the present invention, as shown in FIGS. A so-called glaze layer 34 may be provided, and the recording electrode 22 may be supported thereon. In the end face type thermal head according to the present invention, from the viewpoint of thermal design, it is not necessary to form a glaze layer on the ceramic substrate 20, but the glaze layer is required for improving the substrate surface and finely adjusting the thermal design. It does not matter what is formed.

The recording electrode 22 and the return electrode 24 provided on the ceramic substrate 20, respectively, are made of an ordinary conductive material. In particular, metals such as chromium, titanium, molybdenum, tungsten, nickel, gold, copper and the like are used. And nitrides, carbides, borides and the like of these metals. In addition, the recording electrodes 22
The return electrode 24 is formed on each main plane of the substrate 20 using the electrode material as described above by a normal thin film method, a thick film method, or the like.
Is usually patterned according to the recording density of the head. On the other hand, the return electrode 24 may be patterned in the same manner as the recording electrode 22, but is preferably provided as a common electrode. In this case, they are formed in a layered form by a known appropriate technique, or are joined as plate-shaped electrodes. The thickness of the recording electrode 22 and the return electrode 24 is at least 0.5 μm or more.
Preferably, it is selected to be 1 μm or more, more preferably 3 μm or more. It is also possible to provide a multilayer structure using the above-mentioned electrode material.

On the other hand, the heating resistor 26 provided on the thin portion at the tip of the ceramic substrate 20 is preferably a thin-film resistive film, a thick-film resistive film, or the like having a high heat-resistant pulse characteristic and a high resistance. , A material having a high melting point metal or its alloy as a main component, a material mainly containing a mixture of a high melting point metal or its alloy and any of oxides, nitrides, borides and carbides, or titanium, tantalum, chromium, Zirconium, hafnium, vanadium, lanthanum, molybdenum,
A material mainly composed of nitride, carbide, boride, silicide or the like of at least one element selected from tungsten and the like,
A material containing a ruthenium-based oxide as a main component or the like is appropriately adopted. And such a heating resistor 26
Are formed in a pattern according to the recording density of the head by a normal thin film method or the like, or are provided in a continuous single band shape.

The width of the heating resistor 26 does not need to be the same as the width d of the tip of the ceramic substrate 20. If necessary, the width may be smaller than d or the other surface may be used. Can be formed to cover a wide area.

Further, as shown in FIGS. 4 and 5, the substrate surface of the thin portion located at least at the front end of the ceramic substrate 20 forming the above-mentioned heating resistor 26 does not necessarily have to support the electrodes 22 and 24 (see FIG. 4). It does not need to be a plane (a so-called end face) orthogonal to the so-called main plane, and as shown in FIGS. You may. Furthermore, the end connecting the surface mainly supporting the electrodes 22 and 24 and the surface mainly supporting the heating resistor 26 may be connected at any time with a curved surface having a radius. Can be appropriately adopted.

Incidentally, the end face type thermal head (sample N) according to the present invention manufactured in the structure as exemplified above.
o. 1, 2) and, as a comparative example, a ceramic substrate 20
Head (sample No. 3) manufactured by changing the material of
Table 4 below shows the thermal conductivity characteristics of each of the head (sample No. 5) manufactured according to the configuration of the conventional example 4) and the conventional example.

[0035]

Table 1 Table 1 Sample No. of head configuration Substrate thermal conductivity * radiator thermal conductivity * Remarks Fig. 2, 3 1 0.008 0.04 Invention Fig. 4, 52 2 0.004 0.02 Invention Fig. 2, 3 3 0.001 0.004 Compare Example Fig. 4, 5 4 0.04 0.04 Comparative example Fig. 1 5 0.002 None Comparative example * cal · cm / sec · cm ² · ° C

The sample Nos. As a result of performing an evaluation test for examining printing and image quality by a recording apparatus using the end face type thermal heads Nos. 1 to 5, the sample No. corresponding to the present invention was obtained. In each of the heads 1 and 2, high-quality printing was performed at a high speed with extremely clear and little dot blur, bleeding, tailing, and the like.

On the other hand, the sample No. When heads corresponding to 3, 5 are used, dot blur, bleeding, tailing, etc., which are considered to occur due to heat storage in the head, are seen,
The printing quality was low and the printing quality was unclear. Further, the sample No. In the case where the head corresponding to No. 4 was used, the recording sensitivity was low and the print was light in density.

The specific configuration and embodiments of the present invention have been described in detail with reference to the drawings. However, the present invention is not limited to the above description, and the gist of the present invention is not limited to the above description. It should be understood that various changes, modifications, improvements, and the like can be made to the present invention based on the knowledge of those skilled in the art without departing from the present invention.

[0039]

As is clear from the above description, according to the present invention, excellent print response, high recording sensitivity, and good printing without dot blur, blur, tailing, etc. even at high speed printing. A high quality recording device can be realized.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing an example of a conventional end face type thermal head.

FIG. 2 is a perspective view showing an example of an end face type thermal head according to the present invention.

FIG. 3 is an explanatory sectional view of the end face type thermal head shown in FIG. 2;

FIG. 4 is a perspective view showing another example of the end face type thermal head according to the present invention.

FIG. 5 is an explanatory sectional view of the end face type thermal head shown in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 20 Substrate 22 Recording electrode 24 Return electrode 26 Heating resistor 28 Heat radiator 30 Adhesive material 36 Reinforcement material 32 Protective layer 34 Glaze layer

Claims (3)

(57) [Claims] At least a tip portion of a ceramic substrate is made thin, and a heating resistor is provided on the thin portion.
In an end face type thermal head in which a recording electrode and a return electrode for energizing the heating resistor are supported by the ceramic substrate, respectively, the recording electrode and the return electrode are located at least at the front end of the ceramic substrate, and The ceramic substrate has a lower thermal conductivity than the radiator, and a value of the thermal conductivity is 0.002 cal · cm / sec · cm ² ·. An end-face type thermal head comprising a material having a temperature of not lower than 0.03 cal · cm / sec · cm ² · ° C. 2. The method according to claim 1, wherein at least the tip portion of the ceramic substrate is made thin, and a heating resistor is provided on the thin portion.
In an end face type thermal head in which a recording electrode and a return electrode for energizing the heating resistor are supported by the ceramic substrate, respectively, the recording electrode and the return electrode are located at least at the front end of the ceramic substrate, and The heat radiator is provided so as to be close to the ceramic substrate, and the heat radiator has a higher thermal conductivity than the ceramic substrate, and the value of the thermal conductivity is 0.01 cal · cm / sec · cm ² ··· An end-face type thermal head comprising a material having a temperature of at least ℃. 3. The radiator has a higher thermal conductivity than the ceramic substrate, and has a thermal conductivity value of 0.0
^2. The end face type thermal head according to claim 1, wherein the thermal head is made of a material having a temperature of 1 cal.cm/sec.cm.sup.2.