JP2005329561A - Thermal head and printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent images from becoming blur and dull by suppressing generation of the tailing phenomenon, to contemplate a good thermal efficiency and to achieve energy saving. <P>SOLUTION: A glaze layer 12 is formed to have a first step glaze part 13 and a second step glaze part 14. The first step glaze part 13 is formed at a surface of an alumina substrate 11 and includes a swelling part 13a. The swelling part 13a is formed in an arc shape with a predetermined curvature from a tip side where a discrete electrode 16a and a common electrode 16b are opposed to each other at the first step glaze part 13. The second step glaze part 14 is spherical formed upward at a top part of the swelling part 13a in the first step glaze part 13. Namely, the second step glaze part 14 is projected upward with a desired radius of curvature and with a width corresponding to an interval between the discrete electrode 16a and the common electrode 16b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thermal head and a printer, and more particularly to a technique suitable for use as a sublimation thermal transfer type color printer.

  The thermal head prints directly on thermal paper or prints via an ink ribbon, and is mounted on, for example, a facsimile, a thermal printer, a thermal transfer thermal printer, a sublimation thermal transfer printer, or the like (for example, , See Patent Document 1).

FIG. 3 shows a conventional thermal head.
In FIG. 3, reference numeral 1 denotes an alumina substrate. A glass glaze layer 2 is laminated on the upper surface of the alumina substrate 1, and a heating resistor 3 is provided on the upper surface of the glaze layer 2. An individual electrode 4a and a common electrode 4b that are opposed to each other with a predetermined interval are provided on the upper surface. The surfaces of the individual electrode 4a, the common electrode 4b, and the heating resistor 3 are covered with a protective layer 5 having oxidation resistance and wear resistance.
In the glaze layer 2, the surface of the alumina substrate 1 is not smooth, and if the heating resistor 3 is provided directly on the surface, the heating resistor 3 cannot be formed as a uniform film body. 3 is used for the purpose of smoothing the surface, and is formed with a thickness of, for example, about 50 to 100 μm.

The thermal head having such a configuration is not covered with the individual electrode 4a and the common electrode 4b in the heating resistor 3 when a current flows through the heating electrode 3 through the individual electrode 4a and the common electrode 4b from a power supply control unit (not shown). Joule heat is generated in the part, and the thermal paper (not shown) is colored by the heat, the ink of the ink ribbon is melted to transfer the ink to the paper, and the dye in the ink ribbon is diffused and transferred to the receiving paper Is printed on the paper.
Japanese Patent No. 3240234 (page 3-5, FIGS. 1 to 5)

By the way, although a thermal head of a printer driven by an AC power source is not considered as a problem today, in a portable mobile printer, a battery is used as a driving source and is consumed in addition to printing. Energy cannot be overlooked, and energy saving is required.
However, in the conventional thermal head, the amount of heat generated in the heating resistor 3 at the time of printing is transmitted to the thermal paper or ink ribbon through the protective layer 5 at the same time, and at the same time, the amount of heat equal to or more than that is generated. Since it is transmitted to the glaze layer 2 and the alumina substrate 1, the actual situation is that it is wasted.

Conventionally, as a countermeasure against this, the glaze layer 2 having a thickness of about 50 to 100 μm has a heat storage effect (heat insulation effect), so that it is easy to increase the thickness of the glaze layer 2. However, when the thickness of the glaze layer 2 is simply increased, the heat insulation effect is improved, but the thermal response at the time of printing is reduced by that amount, so the effect of heat storage is also exerted on the part that is not originally printed, A tailing phenomenon occurs, causing a problem that the image is blurred and the image is not sharp.
In addition to the above, in place of the glaze layer 2, it is conceivable to stack a heat storage layer made of a resin such as epoxy or aromatic polyimide, but if so, the thermal efficiency can be improved, but again Since the thermal responsiveness is lost, a tailing phenomenon occurs and the same problem as described above occurs.
On the other hand, in the glaze layer, the portion that protrudes between the individual electrode and the common electrode is formed in a spherical shape and thick, so that the tailing phenomenon is improved accordingly. However, since the portion excluding the spherical portion is thin, there is a problem that the heat storage effect is inferior, and no consideration is given to energy saving when used in a mobile printer.

  The present invention has been made in consideration of such circumstances, and prevents the occurrence of a tailing phenomenon to prevent blurring and blurring of an image, thereby achieving good thermal efficiency and energy saving. It is an object to provide a thermal head and a printer that can achieve the above.

In order to achieve the above object, the present invention proposes the following means.
In the invention according to claim 1, on the substrate, a glaze layer, a heating resistor, an electrode pattern composed of individual electrodes and a common electrode, and a protective layer covering the surface of the electrode pattern and the heating resistor are sequentially formed. In the laminated thermal head, the glaze layer is formed with a thickness of 350 to 500 μm, and has a first-stage glaze portion having a bulging portion that bulges upward in an arc shape; A second-stage glaze portion having a width approximately equal to the interval between the individual electrode and the common electrode at the top of the bulging portion of the glaze portion and protruding in a spherical shape at a height of 1 to 10 μm; It is characterized by having.

As a result, when power is applied to the individual electrode and the common electrode of the electrode pattern, Joule heat is generated in a portion of the heating resistor sandwiched between the individual electrode and the common electrode, and the Joule heat is transmitted through the protective layer. While the recording medium is heated, a part of it is stored in the glaze layer, but since the glaze layer is formed with a thickness of 350 μm to 500 μm, the generated Joule heat can be stored sufficiently and is necessary for subsequent printing. Heat to the heat generating resistor can be recirculated, and the thermal efficiency can be improved.
In addition, the heating resistor is stacked on the surface of the second-stage glaze portion having a height of 1 μm to 10 μm and having the same width as the interval between the individual electrode and the common electrode. Since the protective layer also has a spherical shape similar to that of the second-stage glaze and the heating resistor, the surface pressure per unit area when the protective layer and the recording medium come into contact with each other can be increased. It is possible to suppress the occurrence of the tailing phenomenon in the processed image, and it is possible to prevent the image from being blurred or sharp.
In addition, when the thickness of the glaze layer is thinner than 350 μm, the heat insulation effect cannot be obtained, energy lost other than printing cannot be reduced, and the thickness of the glaze layer is thicker than 500 μm. If this is done, the thermal responsiveness is lost, and a tailing phenomenon occurs due to the influence of animal heat even in a portion that is not originally printed, resulting in image blurring or no image sharpness.
Further, when the height of the second-stage glaze portion is higher than the height of the first-stage glaze portion, the cross-sectional spherical state of the protective layer may be worn early due to friction during use. In addition, if it is higher than 10 μm, it is difficult to form an electrode.

According to a second aspect of the present invention, in the thermal head according to the first aspect, the opposing tips of the individual electrode and the common electrode of the electrode pattern are 1 μm from the top of the second-stage glaze portion to the substrate side. It is provided at a position retracted by 3 μm or less.
As a result, the heat of the heating resistor provided on the surface of the second stage glaze is appropriately transferred to the recording medium via the protective layer, and the heat transfer between the recording medium and the recording medium is hindered. There is no fear.
If the distance between the tip of the individual electrode and the common electrode retreating from the top of the second-stage glaze portion to the substrate side is less than 1 μm, the individual electrode and the common electrode have different thicknesses depending on the thickness of the individual electrode and common electrode. The end portion with the common electrode protrudes from the apex portion of the second glaze portion, so that printing cannot be performed satisfactorily, and the opposing tip of the individual electrode and the common electrode is the second-stage glaze portion. When the distance of retreating from the top of the substrate to the substrate side is larger than 3 μm, the surface area of the heating resistor exposed outward from between the tips of the individual electrode and the common electrode increases, and the exposed portion is discharged to the outside. The amount of heat generated becomes excessive, and the thermal efficiency is deteriorated.
According to a third aspect of the present invention, in the thermal head according to the first or second aspect, a metal structural component is fixed to the bottom of the substrate with an adhesive having a thermal conductivity of 0.5 W / m · K or more. It is characterized by being.
As a result, when the adhesive 18 is configured to have a high conductivity of 0.5 W / m · K or more, the heat stored in the glaze layer is transferred from the alumina substrate to the metal structural component via the adhesive. Therefore, the tailing phenomenon can be further suppressed from occurring.

The invention according to claim 4 is the thermal head according to claim 3, wherein the adhesive is an acrylic resin-based pressure sensitive adhesive.
As a result, when an acrylic resin-based pressure sensitive adhesive is used, not only heat transfer between the substrate and the metal structural component is improved, but also deformation occurs regardless of the difference in thermal expansion between the substrate and the metal structural component. It can be prevented from occurring, and there is no fear that both will peel off.
The invention according to claim 5 includes the thermal head according to any one of claims 1 to 4.
Thereby, a favorable printing can be realized and a clear image can be obtained.

  According to the first aspect of the present invention, since the glaze layer has a heat storage effect and is configured to prevent the thermal responsiveness from being lowered, the occurrence of the tailing phenomenon is suppressed and the image It is possible to prevent the blur and sharpness from being lost, to achieve good thermal efficiency, and to achieve energy saving.

  According to the second aspect of the present invention, there is no possibility that the heat transfer between the recording medium and the recording medium is hindered, so that an effect that the Joule heat generated by the heating resistor can be effectively used is obtained. .

  According to the third aspect of the present invention, excess heat accumulated in the glass glaze layer is smoothly discharged to the outside, so that tailing can be suppressed and image quality can be maintained.

  According to the invention which concerns on Claim 4, even if there exists a thermal expansion difference between a board | substrate and metal structural components, the effect by which the thermal head excellent in flatness can be comprised without producing the wave | undulation by thermal deformation.

  According to the fifth aspect of the invention, there is provided a printer capable of reliably suppressing tailing, obtaining a good print image with small density unevenness, and improving image quality and saving power for mobile use. The effect which can be provided is acquired.

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are views showing a thermal head according to an embodiment of the present invention. FIG. 1 is a sectional view showing the thermal head according to an embodiment of the present invention. FIG. FIG.
In the thermal head 10 of this embodiment shown in FIG. 1, a glaze layer 12 is provided on the upper surface of an alumina substrate 11, and a heating resistor 15 is laminated on the surface of the glaze 12 layer. On the surface of the heating resistor 15, an electrode pattern (not shown) composed of the individual electrode 16a and the common electrode 16b is laminated. The individual electrodes 16a and the common electrode 16b of the electrode pattern are opposed to each other with a predetermined interval. In the heating resistor 15, a portion of the electrode pattern that is not covered with the individual electrode 16a and the common electrode 16b functions as a heating portion.
The individual electrode 16 a, the common electrode 16 b, and the surface exposed to the outside of the heating resistor 15 are covered with the protective layer 17.

Therefore, the thermal head 10 is configured by sequentially laminating the glaze layer 12, the heating resistor 15, the electrode pattern, and the protective layer 17 on the alumina substrate 11.
When the individual electrodes 16a and the common electricity 16b of the electrode pattern are applied by a power supply control unit (not shown), Joule heat is generated in the portion between the individual electrodes 16a and the common electrode 16b in the heating resistor 5, thereby generating an image. It is possible to print on the target recording paper based on the data.
A metal structural component 19 is fixed to the bottom of the alumina substrate 11 via an adhesive 18. The metal structural component 19 is provided with a cooling fan (not shown).

In this embodiment, as shown in FIGS. 1 and 2, the glaze layer 12 is formed having a first-stage glaze portion 13 and a second-stage glaze portion 14.
That is, as shown in FIG. 2, the first-stage glaze portion 13 of the glaze layer 12 is formed on the alumina substrate 11 and has a bulging portion 13a on the surface thereof. The bulging portion 13a is formed in the first-stage glaze portion 13 with a predetermined curvature R1 from the front end side where the individual electrode 16a and the common electrode 16b face each other, and an arc shape is formed between the electrodes 16a and 16b. It bulges out. The second-stage glaze portion 14 has a spherical shape formed further upward on the top of the bulging portion 13 a in the first-stage glaze portion 13. That is, the second-stage glaze portion 14 has a predetermined curvature R2 at the top of the bulging portion 13a and projects upward with a width corresponding to the interval between the individual electrode 16a and the common electrode 16b.

  The formation of the glaze layer 12 will be described in detail. A desired glass paste is printed on the entire upper surface of the alumina substrate 11 and fired to form the glaze layer 12 having a thickness of 400 μm.

Next, a resist film (not shown) is printed on the glaze layer 12, and the non-printed portion where the resist film is not provided is etched with a hydrofluoric acid-based etchant to thereby form a single stage having a height of 50 μm. The eye glaze part 13 is formed. In this case, the first-stage glaze portion 13 has a height including the bulging portion 13 a and the second-stage glaze portion 14.
Next, the resist film is peeled off and the alumina substrate 11 having the first-stage glaze portion 13 is washed, and then the R-shaped heat treatment is performed to form the curvature R1 of the bulging portion 13a to 3 mm.

Subsequently, a resist film (not shown) is printed on the first-stage glaze portion 13 and a non-printed portion where the resist film is not provided is etched with a hydrofluoric acid-based etchant to bulge out. In the portion 13a, a second-stage glaze portion 14 having a spherical shape with the same width as that of the heat generating portion (that is, the interval between the individual electrode 16a and the common electrode 16b) is formed. In this case, the height H of the second-stage glaze portion 14 is preferably 1 μm to 10 μm, and in this example, 5 μm.
As described above, when the glaze layer 12 having the first-stage glaze portion 13 and the second-stage glaze portion 14 is formed, the resist film is peeled off, the glaze layer 12 is washed, and then subjected to heat treatment. The second-stage glaze portion 14 having the height is formed with desired accuracy.

  Thereafter, a heating resistor 15 having a desired thickness is laminated on the glaze layer 12 of the alumina substrate 11, and then an electrode pattern having a thickness of 1 μm is laminated on the heating resistor 15. In this case, in the electrode pattern, the opposing ends of the individual electrode 16a and the common electrode 16b are provided at a position that is lowered downward by a dimension L of 1 μm from the top of the second-stage glaze portion 14 of the glaze layer 12. ing. Accordingly, the top of the second-stage glaze portion 13 protrudes upward by 1 μm. In the heating resistor 15, the portion corresponding to the second-stage glaze portion 14 of the glaze layer 12 is the second-stage glaze portion 14. It has a spherical shape corresponding to the shape of the glaze part 14, and this functions as a heat generating part.

  And after the electrode pattern which consists of the individual electrode 16a and the common electrode 16b is formed, the thermal head 10 is formed by laminating | stacking the protective layer 17 which coat | covers the surface of the electrode pattern and the heating resistor 15. FIG. In this case, the protective layer 17 has a spherical shape corresponding to the second-stage glaze portion 14 and the heating resistor 15 of the glaze layer 12.

Thereafter, in FIG. 1, a metal structural component 19 is fixed to the bottom of the alumina substrate 11 with an adhesive 18. In this case, the adhesive 18 is a thermosetting epoxy resin, acrylic resin, silicone resin, natural rubber, isoprene rubber, silicone rubber in order to improve the thermal conductivity between the alumina substrate 11 and the metal structural component 19. It is preferable to have a high conductivity of 0.5 W / m · K or more by appropriately adding a heat conductive filler such as alumina, beryllia, or magnesia to any of the adhesives.
Among various types of adhesives, acrylic resin pressure sensitive adhesives can be used in the form of A) adhesive transfer tape (double-sided tape type), and can easily impart a uniform film thickness, and B) heat cure. Since there is no need for this, there is no shrinkage at the time of curing, and since a strong viscosity can be maintained even when heated in a subsequent process, deformation due to a difference in thermal expansion between the alumina substrate 11 and the metal structural component 19 is difficult to occur. And undulation due to uneven coating of the adhesive and thermal deformation hardly occurs. For this reason, it is difficult to cause uneven coating of the adhesive 18 and undulation due to thermal deformation, and it is possible to obtain a thermal head 10 having excellent flatness. According to this thermal head, it is possible to obtain a good image with extremely little density unevenness. Can be printed well.

  In the thermal head 10 configured as described above, when a current flows from the power supply control unit (not shown) to the heating resistor 15 through the individual electrode 16a and the common electrode 16b of the electrode pattern, the individual electrode 16a and the common electrode in the heating resistor 15 are flown. Since Joule heat is generated in a portion (heat generating part) sandwiched between 16b, the Joule heat causes the thermal paper as a recording medium to develop color through the protective layer 17, or melts the ink of the ink ribbon as the recording medium. Then, the image data is printed by transferring the ink to the paper or by diffusing and transferring the dye in the ink ribbon as a recording medium to the receiving paper.

  At this time, the Joule heat generated in the heating resistor 15 heats the recording medium via the protective layer 17 as described above, while a part thereof is stored in the glaze layer 12, but the glaze layer 12 has a thickness of 400 μm. Therefore, the generated Joule heat can be stored sufficiently (heat storage effect), the heat to the heating resistor 15 necessary for the subsequent printing can be recirculated, and the heat efficiency is increased accordingly. At the same time, energy saving can be achieved.

  On the other hand, the heating resistor 15 is laminated on the surface of the second-stage glaze portion 14 that protrudes at a height H of 5 μm and has the same width as the interval between the individual electrode 16 a and the common electrode 16. Since the protective layer 17 on the heating resistor 15 has a spherical shape substantially similar to that of the heating resistor 15, the surface pressure per unit area when the protective layer 17 and the recording medium come into contact with each other can be increased. The heat transfer to the recording medium can be increased accordingly. Therefore, it is possible to suppress the occurrence of the tailing phenomenon in the printed image, and it is possible to prevent the blurring and sharpness of the image from being lost, and thus it is possible to obtain a good image with extremely little density unevenness. Can be printed well.

Further, the heat stored in the glaze layer 12 is transmitted to the alumina substrate 11, the adhesive 18, and the metal structural component 19, and is dissipated by cooling fins (not shown) provided in the metal structural component 19. At this time, due to the magnitude of the thermal conductivity of the adhesive, that is, when the thermal conductivity is low, the heat outlet is blocked, so that the heat storage becomes excessive, and a tailing phenomenon may occur during printing.
However, when the adhesive 18 is configured to have a high conductivity of 0.5 W / m · K or more as described above, the heat stored in the glaze layer 12 is transferred from the alumina substrate 11 to the adhesive 18. Can be transmitted well to the metal structural component 19, so that the occurrence of the tailing phenomenon can be further suppressed.

In addition, when an acrylic resin pressure-sensitive adhesive is used as the adhesive 18, a deformation occurs in which both 17 and 19 peel off regardless of the difference in thermal expansion between the alumina substrate 11 and the metal structural component 19. There is no fear that both 17 and 19 will be peeled off.
As a result, the tailing can be surely suppressed, the undulation due to thermal deformation does not occur, the thermal head 10 having excellent flatness can be configured, and a printed image with small density unevenness can be obtained. A printer having the thermal head can reliably suppress tailing and can obtain a good print image with small density unevenness, and can improve image quality and save power for mobile use.

Moreover, although the example in which the glaze layer 12 was formed with a thickness of 400 μm was shown, it may be thicker than that. However, if it is too thick, the thermal responsiveness at the time of printing is lowered. Therefore, considering the thermal responsiveness and the heat storage effect, the glaze layer is desirably in the range of 350 to 500 μm.
Furthermore, although an example using an alumina substrate has been shown, the present invention is not limited to this, and other substrates, for example, a substrate mainly composed of ceramics may be used.

It is sectional drawing which shows the thermal head which concerns on one embodiment of this invention. FIG. 2 is an enlarged explanatory view showing a main part of FIG. 1. It is explanatory drawing which shows the conventional thermal head.

Explanation of symbols

10 Thermal head 11 Alumina substrate (substrate)
DESCRIPTION OF SYMBOLS 12 Glaze layer 13 First stage glaze part 13a Bulging part 14 Second stage glaze part 15 Heating resistor 16a Individual electrode 16b Common electrode 17 Protective layer 18 Adhesive 19 Metal structural component

Claims (5)

In a thermal head in which a glaze layer, a heating resistor, an electrode pattern made up of individual electrodes and a common electrode, and a protective layer covering the surface of the electrode pattern and the heating resistor are sequentially laminated on the substrate.
The glaze layer is formed with a thickness of 350 to 500 μm,
In addition, a first-stage glaze portion having a bulge portion that bulges upward in an arc shape, and a top portion of the bulge portion of the first-stage glaze portion, the same degree as the interval between the individual electrode and the common electrode A thermal head having a width and a second-stage glaze portion protruding in a spherical shape with a height of 1 to 10 μm. The thermal head according to claim 1,
The opposite ends of the individual electrode and the common electrode of the electrode pattern are provided at a position retreated from 1 μm to 3 μm from the top of the second stage glaze to the substrate side. head. The thermal head according to claim 1 or 2,
A thermal head, wherein a metal structural component is fixed to the bottom of the substrate with an adhesive having a thermal conductivity of 0.5 W / m · K or more. The thermal head according to claim 3,
The thermal head according to claim 1, wherein the adhesive is an acrylic resin pressure sensitive adhesive. A printer comprising the thermal head according to claim 1.

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