JP2766325B2 - Thermal recording head - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermal recording head.

[Related Art] A thermal recording head is known as a device for heating a thermal paper or a thermal transfer ink sheet by generating heat in dot units in a thermal recording system using a thermal paper or a thermal transfer recording system using a thermal transfer ink sheet. I have.

In recent years, the thermal recording method and the thermal transfer recording method are also required to have higher quality and higher recording speed due to higher density of recorded images.

In order to realize a high-density and high-resolution recorded image, it is necessary that the heating elements arranged at a high density are thermally independent from each other. It is necessary to reduce the time constant of each heating element to enhance the thermal response of the heating element.

Recently, the arrangement density of the heating elements has been determined to be 16 dots / mm or more, and the heating element has a heat generation time constant of several msec or less.

"Good thermal responsiveness" means that the heating element rapidly rises in temperature when the heating element is heated, and has good rising thermal responsiveness, and when the heating of the heating element is stopped, the temperature of the heating element decreases. It means that the falling thermal responsiveness for rapid decrease is good.

Conventional thermal recording heads use a material with good thermal conductivity, such as alumina, for the substrate that supports the heating element, improve the heat radiation efficiency through the substrate, and improve the falling thermal responsiveness. A glass glaze layer having poor thermal conductivity is provided as an extremely thin layer of about several tens of μm between the heating element and the glass glaze layer to achieve good rising thermal response and thermal independence of each heating element.

[Problems to be Solved by the Invention] As described above, in the conventional thermal recording head, the design principle of the thermal recording head is to perform most of the heat radiation from the heating element through the substrate. In this case, although heat is radiated from the board very efficiently, even when heating the heating element, a considerable part of the amount of heat generated by the heat is radiated by the board, so in order to achieve the required rising thermal response, ,
It is necessary to generate an amount of heat far exceeding the amount of heat necessary for thermal recording itself, and therefore, there is a problem of shortening the life of the heating element due to thermal deterioration. Further, in order to generate a large amount of heat, it is necessary to increase the cross-sectional area of the power supply electrode, and this necessity hinders an increase in the density of the heating element array.

The present invention has been made in view of the above circumstances,
An object of the present invention is to provide a novel thermal recording head which enables high-density and high-speed recording.

[Means for Solving the Problems] A thermal recording head of the present invention is a device for heating a thermal paper or a thermal transfer ink sheet by generating heat in dot units in a thermal recording system or a thermal transfer recording system. , Substrate and
An insulating layer, an electrode, and a protective layer are integrated.

The “heating elements” generate heat in units of dots to heat the thermal paper or the thermal transfer ink sheet, and are arranged in an array.

 The “substrate” supports the heating element.

The “insulating layer” is provided between the heating element and the substrate. This insulating layer is provided to improve the adhesion between the substrate and the heating element.

 The "electrodes" supply power to the individual heating elements.

The “protective layer” is provided so as to sandwich the heating element together with the insulating layer, and protects the heating element. When a recording is made,
The surface of the protective layer contacts the thermal paper or thermal transfer ink sheet.

At least the portion of the substrate that is close to the heating element has a porosity of 0.
It has 1-75% porosity.

The insulating layer has a thickness of 0.01 to 10 μm and a thermal conductivity of 0.1 to 3 J /
It is set in the range of m sec K.

The thickness of the protective layer is set in the range of 1 to 20 μm, the thermal conductivity is set in the range of 1 to 25 J / m sec K, and is set to a value equal to or higher than the thermal conductivity of the insulating layer.

The protective layer may be composed of a single layer,
It is also possible to form a two-layer structure with two layers having different thermal conductivities. In the case of a two-layer structure, a layer having a lower thermal conductivity is provided on the heating element side, and its thickness is made sufficiently thin.

The pores may be distributed over the entire substrate, may be distributed in a layered manner on the substrate side on the heating element side, or may be distributed only on a portion of the substrate close to the heating element.

Further, the insulating layer, the heating element, and the protective layer can be formed on the end face of the substrate, that is, the end face formed by the thickness of the substrate, as in Example 5 described later.

Further, as in a sixth embodiment described later, an insulator and a heating element are formed on the edge of the substrate so as to face the edge of the substrate formed by the thickness of the substrate, and a protective layer is formed on the edge of the heating element and the edge of the substrate. The portion may be formed so as to be covered.

[Operation] Hereinafter, the operation of the present invention will be described in comparison with a conventional thermal recording head.

In order to simplify the discussion, consider a model as shown in FIG. In the figure, reference numeral 10 indicates a substrate, and reference numeral 40 indicates a heating element.

In this model, when a current i is passed through the heating element 40,
Assuming that the resistance of the heating element 40 is r, the amount of heat generated per unit time is proportional to the square of i and proportional to r.

When heat is generated in the heating element 40, the temperature of the heating element 40 increases. However, when a temperature difference occurs between the heating element 40 and the surroundings due to the increase in temperature, heat is immediately released by heat transfer. The characteristics of this heat radiation are defined as the case where there is no thermal paper or thermal transfer ink sheet (hereinafter simply referred to as a sheet) on the heating element 40,
It is considered separately for some cases.

First, considering the case where there is no sheet, the amount of heat radiation from the heating element 40 is the sum of the amount of heat radiation through the substrate 10 and the amount of heat radiation to the surrounding atmosphere of the heating element 40.

The heat radiation to the surrounding atmosphere is determined by the temperature difference ΔT ₁ between the heating element 40 and the surrounding atmosphere and the heat transfer coefficient k ₁ by convection. To this heat radiation amount and per Q ₁ unit time.

The heat radiation to the substrate 10 is determined by the temperature difference ΔT ₂ between the heating element 40 and the substrate 10 and the heat transfer coefficient k ₂ by convection, and this heat radiation amount is defined as Q ₂ per unit time. The amount of heat generated by energizing the heating element 40 and Q ₀ per unit time.

Then, assuming that the amount of heat accumulated in the heating element 40 for a short time ΔT is QΔt, QΔt = Q ₀ Δt−Q ₁ Δt−Q ₂ Δt, and the temperature rise ΔT of the heating element 40 during this
ΔT = QΔt / A, where A is the heat capacity of

Now, the heat radiation to the substrate 10 is heat radiation by heat conduction,
The difficulty of heat transfer by heat conduction is determined by thermal resistance. That is, the thermal resistance R, the area of the heat conduction d as shown in FIG. 2 (III) and conduction distance L by using the heat transfer coefficient k ₂ of the _{foregoing, R = (1 / k 2} ) · (L / d).

In the conventional thermal recording head, the area d is the heating element 40.
Is larger than the dot area, but this is considered to be about the dot area. The conduction distance L is considered to be about the thickness of the substrate 10. Since the substrate 10 is made of a material having high thermal conductivity, the thermal resistance R is small, and therefore, the amount of heat Q ₂ radiated through the substrate 10
Is big. This heat radiation amount Q ₁ from the heating element 40 into the surrounding atmosphere for the smaller Partly thermal transfer coefficient k ₁ is small. In other words, Q ₁ << Q ₂ .

Considering the above, the amount of heat generated in the heating element when a constant current is passed through the heating element for a time t ₀ is shown in FIG. 3 (II).
The heat radiated from the substrate becomes as shown by a curve 3-22 with time, and the heat radiated into the surrounding atmosphere of the heating element becomes as shown by a curve 3-23.
At this time, the temperature T of the heating element changes as shown by a curve 3-24.

After a time t _0, when stopping the power supply to the heating element thereafter heating element is cooled by heat radiation. In other words, the heat radiation through the substrate and the surrounding atmosphere both approaches zero exponentially as indicated by the curves 3-22 and 3-23, and the temperature of the heating element also decreases as indicated by the curves 3-24.
As shown in FIG.

On the other hand, one feature of the thermal recording head of the present invention is that the substrate has pores.

In FIG. 2 (II), reference numeral 10A indicates a substrate having such pores. When the substrate 10A has pores, the substrate 10A
Is radiated through the pores. However, when the size of d is considered to be about the dot area as in the case of the above-described conventional head, the area of heat conduction d due to the presence of the pores And the conduction distance L increases. Therefore, the presence of pores increases the apparent thermal resistance R in the substrate. That it can be made equal or less and the heat transfer coefficient k ₁ of the in heat transfer coefficient k ₂ in the substrate to the ambient atmosphere by distributing the pores in the substrate. Thus, the heating value of the heating element is energized by a constant time t ₀ to the heating element changes as a straight line 3-11 shown in FIG. 3 (I), the heat dissipation through the substrate 10A 3-12 curve in FIG Like, and heating element 10A
The heat radiation from to the surrounding atmosphere is as shown by the curve 3-13 in FIG. The temperature change of the heating element is as shown by a curve 3-14. Compared to a conventional substrate, heat radiation through the substrate 11A is small, and the amount of heat generated by the heating element effectively contributes to a rise in temperature of the heating element itself.

In addition, in the case of the conventional board, since the heat dissipation efficiency through the board is good, the heat generated by the heating element cannot be effectively stored due to the temperature rise of the heating element itself unless the heat capacity of the heating element is large enough. Although good rising thermal responsiveness could not be obtained, it is possible to reduce the heat capacity of the heating element by using a substrate having pores and suppressing heat radiation by the substrate. This means that the size of the heating element itself can be reduced, which is advantageous for increasing the density of the thermal recording head.

However, on the other hand, the temperature of the heating element after the energization of the heating element 10A is stopped, as shown by the curve 3-14 in FIG. In view of this point, when a substrate having pores is used, the falling thermal responsiveness is significantly worse than that of the conventional one.

However, the above consideration is for the case where there is no sheet on the heating element. Actually, when thermal recording is performed, there is a sheet such as a thermal paper or a thermal transfer ink sheet on the heating element,
When power is supplied to the heating element, a substantial portion of the heat generated in the heating element is used for heating the sheet, and after the power supply is stopped, the heat of the heating element is also radiated through the sheet.

Thermal conductivity of 100J / m as substrate for conventional thermal recording head
Those with sec K or more are used. The heat capacity of the sheet is 1-2 J / gK, and the thermal conductivity is 100-1000 mJ / msecK, which is significantly smaller than the thermal conductivity of the substrate. Calculating using these values, in the conventional thermal recording head, the amount of heat consumed for heating the sheet when energizing the heating element is about 40% of the total amount of heat generated. It will be.

Therefore, when there is a sheet on the heating element, in the case of the conventional thermal recording head, the heat radiation characteristics through the substrate are as shown by a curve 3-25 in FIG. 3 (II), and the heat radiation characteristics to the sheet are the curves in FIG. It looks like 3-26. The temperature change characteristic of the heating element itself is almost the same as the characteristic curve 3-24 without a sheet, as shown by the curve 3-27 in FIG.

On the other hand, when a substrate having pores is used, even when a sheet is present on the heating element, the heat radiation characteristics through the substrate 10A are as shown by the curve 3-15 in FIG. Is almost the same as the characteristic curve 3-12 of FIG. In contrast,
The heat dissipation through the sheet is effectively greater than without the sheet, as shown by curve 3-16. Accordingly, when there is a sheet, the temperature change characteristic of the heating element falls as shown by a curve 3-17 in FIG. 3 (I), and the thermal response is effectively improved compared to the case where there is no sheet. In addition, the rising thermal responsiveness is still kept good.

As described above, the use of a substrate having pores makes it possible to reduce the heat capacity of the heating element. Therefore, by using a heating element having a sufficiently small heat capacity, a thermal recording head with good thermal response can be obtained. Can be realized.

The above is the basic principle of the present invention. If this principle is simply described, the design principle of the thermal recording head according to the present invention is that heat generated in the heating element during thermal recording is dissipated more not to the substrate but to the sheet side.

However, in the actual structure of the thermal recording head, an insulating layer is provided between the heating element and the substrate to enhance the adhesion between the heating element and the substrate, and the surface of the heating element on the side of the sheet is protected. A layer is formed.

Therefore, in order to realize the above principle in such an actual structure, first, the thermal conductivity of the protective layer is set to be higher than the thermal conductivity of the insulating layer.

Further, the heat capacity and the thermal conductivity of the recording sheet, that is, the thermal paper or the thermal transfer ink sheet are not uniform. The heat capacity of the sheet is 1-5J / gK, and the thermal conductivity is 100-1000mJ /
m sec K.

Therefore, considering the range of such heat capacity and thermal conductivity in the sheet, and further considering the strength of the structure of the head and the like, in order to achieve the object of the present invention, the insulating layer that determines the heat radiation characteristics of the substrate side The "thickness and thermal conductivity" and the ratio of pores in the substrate, that is, the "porosity" are preferably in the following ranges.

That is, the porosity is 0.1 to 75%, and the thickness of the insulating layer is 0.01 to 10%.
μm, and the thermal conductivity is preferably in the range of 0.1 to 3 J / m sec K.

Regarding the “thickness and thermal conductivity” of the protective layer that determines the heat radiation characteristics to the sheet side, the thickness of the protective layer is in the range of 1 to 20 μm, and the thermal conductivity is 1 to 25 J / m sec K Good range. Of course, the thermal conductivity of the protective layer is set to be higher than the thermal conductivity of the insulating layer.

If the type of the sheet used for recording is specified to a certain extent and the heat capacity and the range of the thermal conductivity are determined, the object of the present invention can be effectively achieved by setting the porosity and the like within the above range accordingly. A possible thermal recording head has been realized.

In addition, a mechanism to detect the heat capacity of the sheet is provided, or a solid black image is formed at the end of the sheet to detect the density, and the amount of electricity supplied to the heating element is adjusted to an optimum value according to the heat capacity of the sheet. It is also possible to perform such recording control as possible, and by performing such control, it is possible to perform appropriate and high-quality recording on many types of sheets.

Hereinafter, the substrate, the insulating layer, and the protective layer will be described in more detail.

One suitable material for the substrate is glass.
Although glass has a very low thermal conductivity even with a dense structure, a lower thermal conductivity can be realized by forming pores in the glass.

To form pores, a method of bubbling gas into molten glass, a method of forming a porous glass by acid treatment of phase-separated glass, a heat treatment of a gel containing water and the like obtained by a sol-gel method, a glass foam You can use the method of making. When SiO ₂ , ZrO ₂ , Al ₂ O ₃ , TiO ₂ , alkali metal, alkaline earth metal, oxides of other metals and mixtures thereof are used as materials, the porosity is 0.1 to 90%, the thermal conductivity is 2
It is possible to produce a highly heat-insulating porous glass of J / m sec K or less with good control. However, considering the conditions of use as the structure of the substrate, the porosity is appropriate from 0.1 to 75%, and in this case, the thermal conductivity is from 0.01 to 1.5 J / msecK.

Other materials for the substrate include porous microcrystals (porous ceramics) such as oxides and nitrides such as Si, Al, Ti, and Zr, and highly heat-resistant resins such as polyimide, fluororesin, and silicone resin. Porous bodies can be mentioned.

Further, as described above, the portion having pores can be provided as a part of the substrate. For example, 50
μm to 5 mm, preferably 50 to 500 μm can be sliced and pasted on a plate-like substrate to form a substrate,
Alternatively, the dried gel obtained by the sol-gel method before heat treatment may be sintered and vitrified, and pores may be formed in a part of the dried gel by heat treatment using a heat source such as a carbon dioxide gas laser.

Next, the insulating layer will be described. This insulating layer is formed to enhance the adhesion between the heating element and the substrate as described above, but at the same time, heat conduction is performed to secure the heat independence between the heating elements. It is necessary that the material has a low rate of electrical insulation. As such materials satisfying the conditions, SiO ₂ , Al
Examples thereof include metal oxides such as ₂ O ₃ , TiO ₂ , and ZrO ₂ .

The thickness of the insulating layer is such that the size of the pores in the substrate is 100 mm to 100 mm.
When μm, 0.01 ~ 100μm is appropriate, as a method of forming an insulating layer without impairing the surface properties of the substrate, CVD, sputtering, spin-coating the metal compound,
There are a method of depositing by roll coating, dip coating and the like, and a method of melting the surface layer of the substrate surface using a heat source such as a carbon dioxide laser or an infrared lamp to smooth the surface.

 Next, the protective layer will be described.

Since the protective layer is a portion that comes into contact with the sheet, abrasion resistance is required. Further, the protective layer must have a function of efficiently transferring the heat of the heating element to the sheet. Therefore, the thermal conductivity is preferably in the range of 1 to 25 J / mseck, and a value higher than that of the insulating layer is required.

The thickness is preferably in the range of 0.5 to 20 μm in consideration of wear resistance.

The material of the protective layer that satisfies these conditions is Si
Examples include metal oxides, metal nitrides, and carbides such as O ₂ , Si ₃ N ₄ , SiC, Ta ₂ O ₅ , TiN, and ZrO ₂ . Further, as described above, the protective layer can be formed in two layers. In this case, in order to enhance the thermal independence between the heating elements, a layer having a low thermal conductivity is formed very thin in contact with the heating elements, and a layer having a high thermal conductivity and abrasion resistance is deposited thereon.

[Example] Hereinafter, a description will be given according to a specific example.

Example 1 In FIG. 1 (I), reference numeral 1 denotes a substrate, 2 denotes an insulating layer,
Reference numeral 3 denotes an electrode, 4 denotes a heating element, and 5 denotes a protective layer.

The substrate 1 is composed of a SiO ₂ glass body obtained by sintering a dry gel containing a small amount of water obtained by a sol-gel method at 1200 ° C. and then heat-treating it again at 1400 ° C. The thermal conductivity of this substrate 1 was 0.4 J / m sec K, and the apparent specific gravity was 1.2 g / c.
m ³ , the pores contained in the substrate have a pore size of 0.3 to 5 μm and a porosity of about 55%.

The insulating layer 2 has a thickness of 0.5 formed by coating the substrate 1 with a coating liquid for forming an SiO ₂ -based film by spin coating.
μm SiO ₂ film.

The electrode 3 is formed as an Au thin film. That is, it is formed by depositing Au to a thickness of 1 μm on the SiO ₂ film as the insulating layer 2 and patterning it into a predetermined electrode shape.

The heating element 4 is formed by sputtering after forming the electrode 3.
Ta ₂ N is deposited to a thickness of about 0.1 μm, is formed by patterning at intervals of 30 × 30 μm, 30 μm, and is arranged in an array in a direction perpendicular to the drawing.

After the heating element 4 is formed, the protective layer 5 is made of SiO ₂ by CVD.
Is deposited to a thickness of about 5 μm.

The heating element array density of the thermal recording head thus obtained is about 16 dots / mm.

The following table shows the results of a trial calculation of the heat transfer status of Example 1 in comparison with a conventional head.

As is apparent from this comparison, the thermal recording head of Example 1 transmits heat to the thermal paper at least twice as much as the conventional example, and the same type of thermal paper or thermal transfer ink sheet is used as the sheet. In the case of 1, the power supply to the heating element can be effectively reduced, and labor saving in thermal recording can be achieved. 60 characters / m using the thermal recording head of Example 1.
When in was recorded, it was found that good printing was possible and that the thermal response was sufficient.

Second Embodiment FIG. 1 (II) shows the structure of a thermal recording head according to a second embodiment. The second embodiment is a modification of the first embodiment, and the portions denoted by the same reference numerals as those in FIG. 1 (I) are the same as the respective portions in the first embodiment.

The difference from the first embodiment lies in the structure of the protective layer 50. That is,
In the second embodiment, the protective layer 50 has a two-layer structure.

First, an SiO ₂ film 51 is deposited and formed on the heating element 4 and the electrode 3 to a thickness of 0.1 μm by the plasma CVD method, and then the source gas is switched to change the Si ₃ N ₄ film 52 to a thickness of 5 μm. The protective layer 50 is formed by deposition.

In the case of the second embodiment, the amount of heat transfer to the substrate side and the sheet side is almost the same as in the embodiment, but the heat transfer in the lateral direction of the substrate is reduced due to the low thermal conductivity of the SiO ₂ layer 51. However, it was confirmed that the thermal independence between the heating elements could be further improved.

Third Embodiment FIG. 1 (III) shows a structure of a thermal recording head according to a third embodiment. Parts denoted by the same reference numerals as those in FIG. 1 (II) are the same as the respective parts in the second embodiment.

The difference from the second embodiment lies in the structure of the substrate 10 and the protective layer 50A.

That is, in the third embodiment, the substrate 1A has a composite structure.
Reference numeral 1a indicates an Al ₂ O plate. Layer 1b provided on this plate
Is obtained by scanning the surface of a porous SiO ₂ glass body having pores produced by the same method as the substrate 1 in Examples 1 and ₂ with a laser beam and flattening the same to 0.1 mm. Pasted on the plate 5a.

The surface of the substrate 1A is good, and the unevenness is 1 μm or less,
There was no problem with the formation of the insulating layer and the like. Example 1
The insulating layer 2, the electrode 3, and the heating element 4 are formed in the same manner as described above, and the SiO ₂ layer 51 is formed thereon to a thickness of 0.1 μm, and the Ta ₂ O ₅ layer 53 is formed to a thickness of 10 μm by sputtering. It was deposited to form a protective layer 50A.

The heat transfer status of Example 3 was substantially the same as that of Example 2.

When printing was performed at 60 characters / min using the thermal recording head of Example 3, it was found that good printing was possible, and that the thickness of the layer 1b having the pores of the substrate was about 100 μm was sufficient. Was.

Fourth Embodiment FIG. 1 (IV) schematically shows the structure of a thermal recording head according to a fourth embodiment. The fourth embodiment is a modification of the third embodiment,
Portions indicated by the same reference numerals as those in FIG. (III) are the same as those in the third embodiment.

 The difference from the third embodiment lies in the structure of the substrate 1B.

That is, as the substrate 1B, a dense SiO ₂ glass plate 1c obtained by sintering a dry gel containing a small amount of water obtained by the sol-gel method at about 1200 ° C. was used, and the heating element 4 on one surface of the plate 1c was used. A heat treatment is applied to the part close to the array arrangement part by a carbon dioxide laser beam in a linear shape with a width of about 100 μm (the longitudinal direction is perpendicular to the drawing), and an area 1d in which pores are generated in this part It has a structure. The thickness of the region 1d is about 100 μm.

The printing characteristics of the thermal recording head of the fourth embodiment are similar to those of the first to third embodiments.
Are almost the same as the printing characteristics of Therefore, it can be seen that it is sufficient to provide a region having a thickness of about 100 μm in the portion having the pores in the substrate near the heating element as in the fourth embodiment.

Fifth Embodiment FIG. 4 (I) shows a structure of a thermal recording head according to a fifth embodiment. The feature of the fifth embodiment is that the insulating layer 2, the heating element 4, and the protective layer 5
Are formed on the end face of the substrate formed by the thickness of the substrate 1.

The substrate 1 is the same as the substrate in Example 1 and has a thickness of 1 mm. The insulating layer 2 is a 0.5 μm thick SiO ₂ film obtained by a dipping method using an SiO ₂ -based coating solution for film formation. According to the dipping method, the insulating layer 2 can be formed on the end face of the substrate as in this example.

On the insulating layer 2, the same position on both sides of the substrate 1,
Au electrodes 3 were formed at a thickness of 1 μm and a width of 30 μm at intervals of 30 μm.

The heating element 4 is composed of 0.1 μm of Ta ₂ N on the insulating layer 4 at the end face of the substrate.
After being deposited to a thickness of m, patterning was performed so as to connect the Au electrodes 3 on both surfaces of the substrate.

Further, a Si ₃ N ₄ film is formed as a protective layer 5 on the heating element 4 by CVD.
Was formed.

This thermal recording head of the end face type has the same effect as the thermal recording heads of Examples 1 to 4, and good printing characteristics can be realized.

When performing color recording, three types of thermal recording heads are required for each of the three primary colors. However, this thermal recording head of the end face type has three thermal recording heads stacked in the thickness direction. Can be deployed. Therefore, the thermal recording head of the end face type has an advantage that the head portion of the apparatus can be made smaller in mounting than the flat type of the first to fourth embodiments.

Embodiment 6 FIG. 4 (II) shows the structure of a thermal recording head according to Embodiment 6. The sixth embodiment is also an end face type thermal recording head as in the fifth embodiment.

The feature of the sixth embodiment is that the insulating layer 2 and the heating element 4 are formed on the edge of the substrate 1 so as to face the edge of the substrate 1, and the protective layers 5A and 5B are formed on the edge of the heating element 4 and the edge of the substrate. In that it is formed so as to cover

An example of the method of manufacturing the thermal recording head according to the sixth embodiment will be described with reference to FIG.

Substrate 1 having a thickness of 1 mm, which is the same as that used in Example 5.
A 0.5 μm thick SiO ₂ film was formed as the insulating layer 2 on the substrate surface of FIG.

On this insulating layer 2, as shown in FIG.
Au electrodes 3 having a width of 10 mm and a width of 10 μm are placed at intervals of 10 μm, 20 μm.
The stripes were arranged in two rows so as to have a thickness of μm.
The spacing between each array is 750 μm as shown, and the thickness of the Au electrode is 1 μm.

Next, in the vicinity of the two-row array of the electrodes 3, FIG.
The heating element 4 was formed as shown in I). That is, the heating element 4
Is a Ta ₂ N layer having a thickness of 0.1 μm, and is patterned so as to cover adjacent portions of two pairs of electrode pairs forming a pair at intervals of 10 μm.

Further, a protective layer (FIG. 4 (I
A protective layer denoted by reference numeral 5A in I) is deposited as a Si ₃ N ₄ layer in the same manner as in Example 5, and thereafter, the portion indicated by the chain line in FIG. 5 (II) is cut with a dicing saw, and cut. A protective layer (protective layer indicated by reference numeral 5B in FIG. 4 (II)) is deposited as an Si ₃ N ₄ layer on the end face of the substrate formed by the method described in Example 5, and FIG. The thermal recording head as shown was obtained. According to this manufacturing method, two thermal recording heads of Example 6 can be manufactured at a time, so that mass productivity is good.

The thermal recording head of the sixth embodiment has the same effects as the thermal recording head of the fifth embodiment, and the printing characteristics are as good as those of the first to fourth embodiments.

[Effects of the Invention] As described above, according to the present invention, a novel thermal recording head can be provided.

Since the thermal recording head of the present invention has the above-described configuration, the amount of power required for thermal recording can be effectively reduced as compared with the conventional thermal recording head. According to trial calculations, recording can be performed with approximately 1/10 the power consumption of the past. Since the cross-sectional area of the electrode can be reduced by this labor saving, fine processing at the time of device construction becomes easy.

In addition, since the heat generating element can have a low heat capacity, a high-speed thermal response equivalent to or higher than that of a conventional heater can be achieved, and a high dot density can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing four embodiments of the present invention, FIGS. 2 and 3 are diagrams for explaining the principle of the present invention, and FIG.
FIG. 5 is a view showing two examples of another embodiment, and FIG. 5 is a view for explaining one example of a method of manufacturing the thermal recording head of the sixth embodiment. DESCRIPTION OF SYMBOLS 1 ... board | substrate, 2 ... insulating layer, 3 ... electrode, 4 ... heating element, 5 ... protective layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-19270 (JP, A) JP-A-63-257652 (JP, A) JP-A-2-217262 (JP, A) JP-A-2- 217263 (JP, A) JP-A-2-220855 (JP, A) JP-A-1-225567 (JP, A) JP-A-53-101426 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 2/335

Claims (3)

(57) [Claims] A heating element, a substrate supporting the heating element,
Heat formed by integrating an insulating layer interposed between the heating element and the substrate, an electrode for supplying power to the heating element, and a protective layer provided so as to sandwich the heating element together with the insulating layer. A recording head, wherein at least a portion of the substrate close to the heating element has pores having a porosity of 0.1 to 75%, and the insulating layer has a thickness of 0.01 to 10 μm and a thermal conductivity of 0.1 to 3
In the range of J / m sec K, the thickness of the protective layer is in the range of 1 to 20 μm, and the thermal conductivity is in the range of 1 to 25 J / m sec K, which is equal to or higher than the thermal conductivity of the insulating layer. A thermal recording head, comprising: 2. The thermal recording head according to claim 1, wherein the insulating layer, the heating element, and the protective layer are formed on an end face of the substrate formed by the thickness of the substrate. 3. The heating device according to claim 1, wherein the insulator and the heating element are formed on an edge of the substrate so as to face the edge of the substrate formed by the thickness of the substrate. A thermal recording head formed so as to cover an end face of a substrate.