JPH0717067A - Thin film type thermal print head and production thereof - Google Patents

Abstract

PURPOSE:To provide a thin film type thermal print head by which printing is suitably performed through a thermal transfer method on the smooth rigid surface of plastic and metal or the like. CONSTITUTION:A glass glaze layer 16 for forming the thin film of a heat- generating part 11 on the surface thereof is formed on a base plate 13 while keeping a sufficient cross direction region. A gentle slope surface or a rounded surface 18 is formed in a part near to the edge part of the glass glaze layer 16 by reburning the slope part or the stepped part after working and forming the same. The gentle slope surface or the rounded surface 18 is made lower as it advances to the edge of the base plate. A part or the whole part in the cross direction of the heat-generating part 11 is positioned on the slope surface or the rounded surface 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film type thermal print head particularly adapted for printing on a smooth hard surface such as a plastic plate or a metal plate by a thermal transfer method, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A thermal print head for printing by a thermal transfer system is roughly classified into the following two types according to the method of forming its heat generating portion. That is,
A thick film type thermal print head and a thin film type thermal print head.

The heat generating portion of the thick film type thermal print head is formed by printing a resistor having a predetermined width by a screen printing method using a resistor paste containing ruthenium oxide or the like as a main component and firing the resistor. This thick film type thermal print head has an advantage that a heating resistor can be formed relatively easily, but has a drawback that it is difficult to form fine heating dots.

On the other hand, the thin film type thermal print head is
As described in detail later, on the glass glaze layer formed on the substrate, a resistor layer such as tantalum nitride is formed into a thin film by sputtering or the like, and a conductor pattern made of a conductive metal such as aluminum is further formed thereon by sputtering or the like. It has a thin film structure. Such a thin film type thermal print head has an advantage that the heating dots can be easily miniaturized and the printing speed can be increased, but the manufacturing process is complicated and the cost is relatively high. There is also a drawback.

By the way, the thermal transfer printing system includes a fusion type thermal transfer system and a sublimation type thermal transfer system. Looking at this for the gradation of the image, the fusion type thermal transfer method
Since the difference in the gradation of light and shade must be obtained depending on the area, even if the density of the heating dots of the print head is made fine, the number of gradation steps cannot be increased. Only by controlling the amount of energy, it is possible to obtain stepless gradation.

On the other hand, recently, development for performing color printing by a thermal transfer system has been actively made, and faithful reproduction of color photographs is being demanded. To achieve this goal, a thin film thermal print head is used as a print head type in order to reproduce a color photograph having a gradation of stepless gradation with a resolution density of a certain level or more by printing by a thermal transfer method. As a result, the sublimation type is suitable.

For the above reasons, thin-film thermal print heads are often used for high quality color printing. The conventional general thin film type thermal print head of this type is configured to perform printing on an easily bendable sheet material such as paper.

14 to 16 show an example of a general structure of the heat generating portion 2 of the conventional thin film type thermal print head 10. A glass glaze layer 4 is formed on the upper surface of the ceramic substrate 3.
a and 4b are formed by screen printing using glass paste and firing. As shown in FIG. 15, the glass glaze layer is a main portion 4 on which many parts of the drive IC (not shown) and the conductor wiring pattern 5 should be mounted.
a and a partial glaze layer 4b formed in a narrow width so as to be separated therefrom.

The reason why the partial glaze layer 4b is provided is that the convex portion is formed by the partial glaze layer 4b and the heat generating portion 2 is arranged on the convex portion.
This is for ensuring the contact of the heat generating portion 2 with the recording paper such as paper to be printed. On the surface of the partial glaze layer 4b, the heating resistor layer 6 is formed into a thin film by sputtering or the like. Then, the resistor layer 6 near the top of the partial glaze layer 4b is made to face the strip shape in the longitudinal direction of the partial glaze layer 4b, and the conductor wiring pattern layer 5 of a predetermined form is formed into a thin film by sputtering or the like using aluminum or the like as a material. To be done. Furthermore, a protective glass layer 7 is formed by sputtering or the like so as to cover the layers 6 and 5.

[0010]

By the way, the partial glaze layer 4b is formed by printing by screen printing method using glass paste or firing, although its width is extremely thin, about 100 to 200 .mu.m. . Since the glass paste is once fluidized in the firing process, the partial glaze layer 4b is formed as shown in FIG.
As shown in FIG. 5, although it has an arc cross section, since it is screen printing, the accurate linearity of the edge of the glass paste immediately after printing cannot be ensured and the ceramic substrate surface at each site in the substrate longitudinal direction is Since the wettability varies, the partial glaze layer 4b after printing and baking has undulations on the edges on both sides in the width direction, as shown in an emphasized manner in FIG. 16, which causes the partial glaze layer 4b. The swell also occurs at the top height of the. The degree of such waviness is, for example, 1 mm in the longitudinal direction.
It has been confirmed that it is 1 μm or more.

Even if the top of the partial glaze layer 4b is undulated as described above, it is possible to print on a sheet-shaped printing object such as paper which is easily bent while backing it up with a rubber platen. As long as it is done, there is almost no problem in print quality. Because the amplitude of the waviness is on the order of a few μm, as long as the elastically deformable platen presses the flexible sheet against the top of the wavy glass glaze layer, the sheet is stretched in the longitudinal direction of the glass glaze layer. This is because it can be pressed with a substantially uniform pressing force over the entire length in the direction.

With the widespread use of thermal transfer type color printing, for example, thermal transfer type color printing is applied to an object having a hard and smooth surface such as a plastic card such as a prepaid card, a cash card or an IC card. The need to do so is emerging. However, it has been found that the thin film thermal print head having the conventional general structure as shown in FIGS. 14 to 16 cannot perform proper printing on an object such as the plastic card. The reason is that there is undulation in the partial glaze layer 4b or the heating portion formed on the top thereof, and the degree of this undulation is
Even if it is about several μm in a length of 1 mm, the heat generating part has a uniform pressure in each part in its longitudinal direction on a target surface that has smoothness like a plastic card and cannot be easily bent. This is because the target surface cannot be touched.

When printing is performed on a smooth surface such as a plastic card by the conventional thin film thermal print head described above, a striped pattern due to light and shade appears remarkably.

The present invention has been devised under the above-mentioned circumstances, and enables fine printing to be appropriately performed on a smooth hard surface such as a plastic or metal plate by a thermal transfer method. It is an object of the present invention to provide a thin-film type thermal print head configured as described above and a manufacturing method thereof.

[0015]

In order to solve the above problems, the present invention takes the following technical means.

According to the invention described in claim 1 of the present application, the glass glaze layer formed on the surface of the substrate, the resistor layer formed as a thin film on the surface of the glass glaze layer, and the resistor layer formed on the resistor layer. A thin film thermal print head comprising a conductor pattern layer, and configured to function as a heat generating portion for individually heating the strip-shaped region of the resistor layer for each unit length in the form of the conductor pattern layer. The glass glaze layer is formed with a sufficient width direction region, and is formed in a region near the edge of the substrate so as to have a gently inclined surface or a round surface that becomes lower toward the edge of the substrate. A part or all of the heat generating portion in the width direction is characterized by being located on the inclined surface or round surface.

The invention described in claim 2 of the present application is a method for manufacturing a thin film type thermal print head, and in particular, formation of an inclined surface or round surface of the glass glaze layer defined in the invention of claim 1 above. It is characterized by the method.

That is, in this method for manufacturing a thin film type thermal print head, a glass glaze layer is formed in a sufficient width direction region from an edge portion of a substrate surface, and a resistor layer is thinly formed at a predetermined portion of the glass glaze layer. A thin film type thermal printhead including forming a predetermined conductor pattern layer on the resistor layer and forming a band-shaped region of the resistor layer as a heating portion capable of individually generating heat for each unit length. In the manufacturing method, the glass glaze layer is formed by printing and firing using a glass paste to a constant thickness down to the edge of the substrate, and a portion of the glass glaze layer having a constant thickness near the edge of the substrate. By forming a sloped portion or a stepped portion in the step of forming a glass glaze layer and then re-baking the glass glaze layer. A gentle sloped surface or round surface is formed in the vicinity of the edge so as to be lower toward the edge of the substrate, and the width direction of the heat generating part is formed on the sloped surface or round surface of the glass glaze layer. It is to arrange parts or all.

As a concrete method for processing and forming the inclined portion or the stepped portion in the vicinity of the substrate edge portion of the glass glaze layer in the above method, for example, cutting with a rotary grindstone (claim 3) or blasting method There is (claim 4).

[0020]

The thin film thermal print head of the present invention is characterized by the form of the glass glaze layer for forming the heat generating portion and the method for forming the glass glaze layer.

The difference in morphology between the glass glaze layer for forming the heat generating portion in the conventional thin film thermal print head and the glass glaze layer in the present invention is that the glass glaze layer in the conventional print head has a narrow portion. In contrast to the glaze layer, the glass glaze layer of the present invention has a sufficient width direction region.

In the glass glaze layer, near the substrate edge, a gentle sloped surface or round surface is formed, which becomes lower toward the edge of the substrate, and the heat generating portion is formed on the sloped surface or round surface. Will be done.

In the present invention, the gently sloping surface or round surface in the glass glaze layer in which the heat generating portion is to be formed as described above is formed through the following steps, in particular. That is, as defined in claim 2 above, first, a glass glaze layer having a constant thickness is formed to the edge of the substrate by printing and firing using a glass paste, and then the substrate edge of the glass glaze layer having this constant thickness is formed. The inclined portion or the step portion is formed by processing in the vicinity of the portion, and then the glass glaze layer is fired again. By re-baking after the above-mentioned processing formation, the glass glaze layer,
It is fluidized in the inclined portion or the stepped portion, and as a result of the action of surface tension or the like, it becomes a gently inclined surface or a round surface.

The inclined surface or round surface of the glass glaze layer in the present invention thus formed is
It will have linearity without waviness. The first reason is that since the glass glaze layer itself basically has a sufficient width direction region, a portion that planarly borders the substrate surface in the vicinity of the inclined surface or the round surface where the heat generating portion is to be formed is Therefore, there is no waviness due to edge irregularity during screen printing or difference in wettability to the substrate, and the second reason for this is that smooth sloped surface or round surface does not flow during rebaking. Since the formation of the inclined portion or the stepped portion on the glaze layer prior to the achievement of the liquefaction phenomenon is performed by processing, the glass fluidization phenomenon at the time of the above re-firing should be performed uniformly in each longitudinal direction portion. That is what you can do.

As a result of the above, in the thin-film thermal print head of the present invention, the gently sloping surface or round surface formed in the vicinity of the substrate edge of the glass glaze layer formed with a sufficient widthwise area is the substrate longitudinal direction. A high degree of linearity will be secured. In other words, unlike the partial glaze layer in the conventional thin film thermal printhead, there is almost no problematic waviness at the top.

Therefore, by using the thin film type thermal print head of the present invention, it becomes possible to print on a plastic card or an object having a smooth hard surface such as metal without any problem.

Further, since the heat generating portion is formed on the gently sloping surface or round surface provided in the vicinity of the substrate edge portion of the glass glaze layer, the entire head is inclined with respect to the smooth surface as described above. While doing so, the heat generating portion can be brought into contact with the target surface conveniently.

As described above, according to the thin film type thermal print head of the present invention, it is possible to perform printing by the thermal transfer system on an object having a smooth hard surface without any problem.

In the present invention, since the capacity of the glass glaze layer is increased, the heat generation property may be decreased and the energy efficiency may be decreased. However, when printing by the sublimation type thermal transfer system, In the first place, since the energy to be applied to the heat generating portion is sufficiently large and the feeding speed in the sub-scanning direction is slow, printing can be performed without any problem.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described below.
A specific description will be given with reference to the drawings.

FIG. 1 is a plan view of the thin-film thermal print head 10 of the present invention, FIGS. 2 and 3 are sectional views showing the main part of the thermal print head 10, and FIG. 4 is an enlarged plan view of the heat generating portion 11. Are shown respectively.

A head substrate 13 is superposed and fixed on a heat dissipation plate 12 made of an aluminum plate or the like having a predetermined thickness. A heat generating portion 11 extending in the longitudinal direction of the substrate is formed in the vicinity of one edge portion of the upper surface of the head substrate 13, and the heat generating portion 11 is divided into predetermined lengths on the other side portion. A plurality of drive ICs 14 for independently driving each heating dot are mounted. The head substrate 13
An external connection cable such as a so-called flexible board 15 is connected to the side of the drive IC mounting portion.

Specifically, the heat generating portion 11 is formed as follows. As shown in FIGS. 2 and 3, a glass glaze layer 16 is formed on the surface of a substrate 13 made of alumina ceramic or the like. The glass glaze layer 16 in the present invention has a sufficient area in the substrate width direction. As will be described later, since the conductor pattern layer 17 is formed on the glass glaze layer by sputtering, the glass glaze layer 16 can be provided over the entire width direction of the substrate.

As shown in FIGS. 2 and 3, a gentle sloped surface or round surface 18 is formed near the substrate edge of the glass glaze layer 16 and becomes lower toward the edge of the substrate. It The present invention is also characterized by the method for forming such an inclined surface or round surface, the details of which will be described later.

The basic thickness of the glass glaze layer 16 is, for example, 70 μm, and the widthwise dimension of the region where the gently inclined surface or the round surface 18 is formed is, for example, 400 to 500 μm.

A resistor layer 19 made of, for example, tantalum nitride is formed as a thin film on the surface of the glass glaze layer 16 by sputtering or the like. This resistor layer 1
The thickness of 9 is, for example, 0.05 to 0.15 μm. The region where the heating resistor layer 19 is to be formed is at least the inclined surface or the round surface 1
8 should be included, but may be formed in an appropriate range.

Further, on the resistor layer 19 shown in FIG.
The conductor pattern layer 17 having a planar shape as shown in (3) is formed into a thin film by sputtering using aluminum as a material, for example. The hatched area in FIG. 4 is a strip-shaped area as the heat generating portion 11 formed facing the resistor layer 19. As shown in FIG. 4, a slit 20 is formed by etching or the like in the strip-shaped region serving as the heat generating portion, and is divided into strip-shaped heat generating units (dots) 11a extending in the width direction of the heat generating portion. There is. In FIG. 4, a pattern 17a is a drive pattern connected to the drive IC, and one of the patterns 17b is a common pattern. For example, when one of the drive patterns indicated by reference numeral 17a in FIG. 4 is energized, a current flows as indicated by an arrow in FIG. 4, and a region indicated by a mesh line in FIG. 4 generates heat.

The protective layer 2 made of glass is provided so as to further cover the resistor layer 19 and the conductor pattern layer 17.
1 has a thickness of 4 to 5 μm and is formed by sputtering or the like.

By the way, the above-mentioned glass glaze layer 16
The gently sloping surface or round surface 18 in the vicinity of the substrate edge is formed in the following manner in the present invention.

FIGS. 5 to 10 show the glass glaze layer 1
6 shows a first embodiment of the method for forming the inclined surface or round surface 18 of No. 6 above. First, as shown in FIG. 5, a glaze layer 16 having a constant thickness is formed on the surface of the ceramic substrate 13 by printing and firing. As shown in FIG. 5, the glaze layer 16 is formed on the collective substrate to be divided into each unit substrate in the subsequent step by the dividing line PL. Therefore, regarding the unit substrate,
The glaze layer 16 is formed with a constant thickness up to the edge thereof.

Next, a groove 16a having a predetermined width is formed on the surface of the glaze layer 16 by the sandblast method. For this purpose, for example, a mask plate 22 having an opening similar to the groove region to be formed is brought into close contact with the surface of the glaze layer, and sandblasting is performed from above to the mask plate 22, as shown in FIG. The groove 16a can be formed on the surface of the glaze layer 16. The groove depth can be set to 50 μm, for example. Management of groove depth is
It can be performed relatively easily by adjusting the strength and time of sandblasting.

Next, in the central portion of the groove 16a formed by the sandblast, a fine groove 24 reaching the material substrate 13 is formed by, for example, a dicing blade 23. As a result, the stairs are accurately formed in the substrate end region of the glaze layer 16.

Next, the material substrate in the state of FIG. 9 is refired. The heat at this time causes the above-mentioned stairs to fluidize,
Due to the surface tension, a gentle rounded portion 18 as shown in FIG. 10 is formed and cured in this state.

As described above, the thin film formation of the resistor layer 19 and the thin film formation of the conductor pattern layer 17 are performed on the upper surface of the glass glaze layer 16 in which the gentle round portion is formed in the vicinity of the edge of the substrate. And the protective layer 21
Is formed.

As shown in FIG. 2, the heat generating portion 11 is entirely located on the round surface 18 in the width direction, or as shown in FIG. Is located in. Such a difference can be achieved by changing the aluminum of the round surface, if necessary.

The material substrate 13 which has undergone the steps up to the formation of the protective layer 21 in this way is divided along the dividing line PL to be an individual substrate.

The processing for the glass glaze layer 16 for forming the inclined surface or the round surface 18 may be performed by providing the stepped portion as described above and also by providing the inclined portion as shown in FIG. As shown in FIG. 11, such an inclined portion can be easily formed by cutting with a dicing blade 23a having an inclined peripheral surface.

In the method shown in FIGS. 5 to 10, the groove 16a may be formed by sandblasting or may be formed by cutting with a dicing blade having a predetermined width.

It is easier to control the groove depth from the surface of the glaze layer by the sandblast method, and in a situation where the thickness of the material substrate 13 or the reference thickness of the glaze layer 16 may vary, the glaze layer It is preferable to use the sand blast method, which makes it easy to control the depth from the surface of 16.

The height of the inclined surface or round surface 18 formed in the vicinity of the substrate edge of the glass glaze layer 16 formed as described above is guaranteed to be linear in the substrate longitudinal direction. In other words, the waviness as seen in the partial glaze layer 4b in the conventional thermal print head 1 is significantly reduced.

This is clear in view of the cause of the undulation in the conventional partial glaze layer 4b. As already described in the section of the prior art, in forming the narrow glass partial glaze layer by screen printing or firing, accurate linearity is not ensured at the edge of the glass paste immediately after printing by the screen, and The main cause of the above-mentioned undulation is that the wettability with respect to the substrate varies from place to place when the glass paste is fluidized by heat during firing. In the method for forming the glass glaze layer according to the present invention described above, the cause of the waviness of the partial glaze layer in the above conventional example,
It has been removed altogether.

That is, since the glass glaze layer 16 itself is formed in a sufficient width direction region, the glass glaze layer planarly contacts the substrate on the side of the driving IC side with respect to the heat generating portion. In addition, since the inclined surface or the step portion is formed in the glaze layer after the first step by accurate processing as a step before the formation of the inclined surface or the round surface 18, the inclined portion is not formed. Or, even if the staircase is fluidized during re-firing, such fluidization can be uniformly performed in various parts in the longitudinal direction regardless of the wettability with respect to the substrate. However, the cause of the undulation after firing completely disappears.

Therefore, according to the thin-film thermal print head of the present invention, its heat generating portion can be uniformly pressed in the longitudinal direction against a hard smooth surface such as a plastic plate or a metal plate. As a result, for the first time, printing by a thermal transfer method onto a hard smooth surface, which was not possible with the thin film type thermal print head of this type in the past, has become possible.

As shown in FIGS. 2 and 3, the heat generating portion 11 is partially or wholly formed on the inclined surface or the round surface 18 provided on the glass glaze layer 16, and therefore, on the smooth surface F to be printed. On the other hand, by tilting the print head 10 as shown in FIG. 1, the heat generating portion 11 is brought into contact with the printing target smooth surface F while conveniently avoiding the interference of the IC 14 mounted on the head substrate with the printing target surface F. It is possible. Although not shown in FIG. 1, an ink ribbon is interposed between the print target smooth surface F and the print head 10.

It is particularly suitable for the thin film type thermal print head of the present invention to employ a sublimation type ink ribbon as this ink ribbon and drive the head by a sublimation system for printing. Since the glass glaze layer 16 is present over a sufficient area in the width direction, the heat storage performance immediately below the heat generating portion may be deteriorated and the energy efficiency may be deteriorated. However, in the sublimation type printing method. Is the heating unit 11
Is sufficient energy is supplied and the printing speed in the sub-scanning direction is relatively low, so that the low heat storage performance of the glass glaze layer does not substantially affect printing quality. .

Of course, the scope of the present invention is not limited to the above embodiments. Glass glaze layer 1
6, heating resistor layer 19, conductor pattern layer 17, protective layer 2
The thickness of 1 can be variously set within a common sense range in the category of the thin-film thermal print head.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of a thin film type thermal print head of the present invention.

FIG. 2 is a cross-sectional view of a main part of the thermal print head of FIG. 1, showing a type in which a heat generating part is located on a gently inclined surface.

3 is a cross-sectional view of a main part of the thermal print head of FIG. 1, showing a type in which a heat generating part is located on a round surface.

FIG. 4 is an enlarged plan view of a heat generating portion in the thermal print head.

FIG. 5 is a first embodiment of the method for forming the thermal print head, and shows a step of forming a glaze layer on the surface of the ceramic substrate.

FIG. 6 is a first embodiment of the method for forming the thermal print head, and shows a step of performing sandblasting on the glaze layer formed in FIG.

FIG. 7 is a first embodiment of the method for forming the thermal print head, showing the grooves formed by the sandblasting process of FIG.

8 is a first embodiment of the method for forming the thermal print head described above, showing a step of forming a fine groove in the center of the groove formed in FIG.

FIG. 9 is a first embodiment of the method for forming the thermal print head described above, showing a step portion formed by the grooves and the narrow grooves formed by the steps of FIGS. 6 and 8.

10 is a first embodiment of the method for forming the thermal print head, showing a state where the printed circuit board in the state of FIG. 9 is re-fired.

11 is a second embodiment of the method for forming the thermal print head, showing a step of forming an inclined portion by cutting on the glaze layer of FIG.

FIG. 12 is a second embodiment of the method for forming the thermal print head, showing an inclined portion formed by the cutting process of FIG. 11.

13 is a second embodiment of the method for forming the thermal print head, showing a state where the printed circuit board in the state of FIG. 12 has been re-fired.

FIG. 14 is a plan view of a conventional thin film thermal printhead.

15 is a sectional view taken along line XV-XV in FIG.

16 is a schematic perspective view seen from above in FIG.

Claims (5)

[Claims] 1. A conductor comprising a glass glaze layer formed on the surface of a substrate, a resistor layer formed as a thin film on the surface of the glass glaze layer, and a conductor pattern layer formed on the resistor layer. A thin-film thermal print head configured to function as a heating portion for individually heating the strip-shaped region of the resistor layer for each unit length depending on the form of the pattern layer, wherein the glass glaze layer is sufficiently The heat generating portion is formed so as to have a gentle sloped surface or a rounded surface which becomes lower toward the edge of the board in the vicinity of the board edge. A thin-film thermal print head characterized in that all or all of them are located on the inclined surface or round surface. 2. A glass glaze layer is formed in a sufficient width direction region from an edge portion of a substrate surface, a resistor layer is formed into a thin film at a predetermined portion of the glass glaze layer, and a predetermined conductor pattern is formed on the resistor layer. A method of manufacturing a thin-film thermal printhead, comprising forming a layer to form a strip-shaped region of the resistor layer as a heating unit capable of individually generating heat for each unit length, the glass glaze layer Is a step of forming a constant thickness down to the edge of the substrate by printing and firing using a glass paste, and a step of processing and forming an inclined portion or a step portion in the vicinity of the edge of the glass glaze layer of this constant thickness. After the processing, the glass glaze layer is re-fired, and the glass glaze layer is formed so as to be gradually lowered toward the edge of the substrate in the vicinity of the edge of the substrate. Thin-film thermal printing, characterized in that a wide inclined part or a round surface is formed, and a part or all of the heating portion in the width direction is arranged on the inclined surface or round surface of the glass glaze layer. Head manufacturing method. 3. The step of processing and forming the inclined portion or the step portion is performed by cutting with a rotary grindstone.
the method of. 4. The step of processing and forming the stepped portion comprises:
The method according to claim 2, which is performed by a blast method. 5. A thin film type thermal print head manufactured by the method according to claim 2, 3 or 4.