JPH07323595A - Thermal printing head - Google Patents

Abstract

PURPOSE:To obtain sufficiently high printing efficiency and to enhance the degree of freedom of arrangement by forming a heating region so that the common center line thereof is positioned on the side of the approach end surface of a head substrate from the top line on the surface of a glaze layer on the basis of the surface of the head substrate to extend to a position higher than the upper surface of a driving IC. CONSTITUTION:A glaze layer 6 consists of a flat part 6a and a protruding part 6b and a common electrode 8 and a plurality of individual electrodes are formed on the glaze layer 6 on the side of the side surface 14 on the approach side of a head substrate 5 at the same pitch through a resistor film 7 toward the apex of the protruding part 6b. The common center line extending between the common and individual electrodes 8, 9 of a heating region extends in close vicinity to the approach side surface 14 of the head substrate 5 from the top line on the surface of the protruding part of the glaze layer 6. Further, since a driving IC is mounted on a circuit board separately from the head substrate 5, high printing efficiency is obtained even at the time of the formation of a color image and the degree of freedom of arrangement can be ensured at the same time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head,
In particular, the present invention relates to a thermal head structure suitable for printing by thermal transfer and color printing.

[0002]

2. Description of the Related Art Conventionally, printers for office automation equipment such as facsimiles, printers for ticket vending machines, label printers, etc.
2. Description of the Related Art Thermal print heads that form necessary image information by selectively applying heat to a heat-sensitive medium are widely used. The thermal print head is generally a thin film type thermal print head formed into a thin film on a substrate or a glass glaze layer through a process such as sputtering by a method of forming a heating resistor layer, an electrode layer and the like, and screen printing and It is roughly classified into a thick film type thermal print head formed through a process such as firing.

A conventional thermal print head will be described by taking a thick film type as an example. As shown in FIG. 6, an insulating substrate 21 made of ceramic or the like and a heat storage body formed on the surface of the insulating substrate 21 are used. Glass glaze layer 22 and a common electrode 23 formed on the glass glaze layer 22 in a comb shape
And a plurality of individual electrodes 24 formed corresponding to the common electrode
A heating resistor layer 25 formed so as to cross over the tip portions of the common and individual electrodes, and the common and individual electrodes 23, 2
And a driving IC 26 for selectively applying a required voltage to each individual electrode 24 in order to selectively generate heat in the heating resistor 25 between the four electrodes, that is, in the heating region. Each individual electrode 24 is electrically connected to a correspondingly mounted driving IC by a conductive wire 27 such as gold.

The thick film type thermal print head thus constructed is selectively required for each individual electrode 24 through the driving IC while the common electrode 23 is held at a constant potential when used. By applying the voltage of
An image is formed by heating on the heat-sensitive medium 29 that is selectively energized in each heat generation region and pressed and moved by the platen roller 28.

On the other hand, the thin film type thermal print head is
A thick-film type, except that a plurality of heating resistor layers are formed in strips on the glaze layer formed on the insulating substrate, and common and individual electrodes are provided facing each other on each heating resistor layer. The same structure as the one is adopted.

[0006]

In recent years, the spread of the thermal print head has been expanded with the improvement of the technology of the thermal print head, and various studies have been conducted on its use in the area of color printing. In recent years, also in the field of thermal print heads, researches for forming color images have been actively conducted. Since so-called solid printing is relatively frequently used in color image formation, higher printing efficiency is required as compared with normal printing, and therefore a larger amount of current is required to be supplied to the common electrode. It Therefore, in the thermal print head for color printing, it is required that the width of the common connection portion of the common electrode be sufficiently wide.

However, in the structure of the conventional thermal print head described above, in order to form the common connection portion of the common electrode 23 in a width dimension capable of supplying a sufficient amount of current for color image formation, a heating resistor is required. Body 25 and insulating substrate 2
A sufficient distance must be provided between the side surface of the common electrode 1 and the side surface on the side close to the first electrode 1, and the common connection portion of the common electrode 23 must be formed using this distance. Therefore, it is difficult to reduce the size of the entire insulating substrate in the width direction beyond a certain level.

Further, in the conventional thermal print head, the heating resistor layer 25, the electrode layers 23, 24, and the electrode layers 23, 24 are formed almost entirely on the surface of the insulating substrate 21 by using the above-mentioned thin film type technique or the thin film type technique. Moreover, since the insulating layer itself cannot be miniaturized because the protective layer and the like are formed, it is not possible to sufficiently satisfy the demand for manufacturing cost reduction. Furthermore, in a color printing application, when a plurality of thermal print heads of different colors are provided for printing magenta, cyan, yellow, etc., in order to increase the printing efficiency of each thermal print head, the heat-sensitive medium should have an insulating property. A heat generating area is provided to form a certain angle with the top surface of the substrate to increase the contact resistance with the heat-sensitive medium and to increase the degree of freedom in arranging each thermal print head with respect to a single platen roller, thus simplifying the entire apparatus. In addition, it must be considered to be small in size.

On the other hand, in so-called thermal transfer (sublimation type, wax type, resin type, etc.) using a transfer film in monochrome printing, in order to obtain a good image quality, the wax or resin on the transfer film is transferred onto a printing medium. It must be peeled off from the transfer film immediately after it is transferred to, and for that purpose, a large angle between the printing medium immediately after printing and the transfer film must be provided.

Accordingly, it is an object of the present invention to provide a thermal print head which can obtain a sufficiently high printing efficiency and has a high degree of freedom of arrangement even when it is used for thermal transfer or color image formation. It is in.

[0011]

In order to achieve the above object, according to the present invention, there is provided a common head substrate having a glaze layer formed on the surface thereof, and a common connection portion formed on the head substrate and commonly connected. An electrode, an individual electrode formed corresponding to the common electrode, a heating resistor formed so that a heating area is provided between the corresponding common and individual electrodes, and a drive electrically connected to the individual electrode And a common center line of the heat generating region is located at a position closer to the end face side of the head substrate than the top line on the surface of the glaze layer with respect to the head substrate surface, and from the upper surface of the driving IC. Also provided is a thermal print head characterized in that it is formed so as to extend to a high position.

The glaze layer may include a flat portion that is substantially flat with respect to the surface of the head substrate and a convex portion that rises higher than the flat portion, and the heat generating region may be provided on the convex portion. . The thermal print head may further include an electrically insulating circuit board having an electric wiring pattern formed of a conductive material on the surface thereof, and the head board may be mounted on the circuit board.

The head substrate has a side surface conductive layer electrically connected to a common electrode on at least one side surface thereof, and the common electrode is electrically connected to an electric wiring pattern of the circuit board via the side surface conductive layer. It may be configured to.

[0014]

In the heating area, the common center line extends to a position closer to the end face of the head substrate than the top line on the surface of the glaze layer with respect to the surface of the head substrate and higher than the upper surface of the driving IC. Since it is formed as described above, it is easy to set the contact angle of the heat-sensitive medium that comes into contact with and moves on each heat-generating region, for example, to 0 to 30 °, so that the heat-sensitive medium on the heat-generating region can be easily moved. The concentration of pressure can be improved sufficiently,
It is possible to obtain high printing efficiency and at the same time drive IC
It is possible to provide the upper surface of the substrate, and therefore the wires connected to them and the protective film that covers them, in a sufficiently low positional relationship with respect to the heat generating region. Therefore, when applied to color printing, it is possible to greatly improve the degree of freedom of arrangement when providing a plurality of thermal print heads on a single platen roller, and it is possible to simplify the overall configuration of the apparatus and reduce the size. In addition to being able to contribute, when applied to printing by thermal transfer, it is possible to set a large angle formed between the print medium and the transfer film immediately after the transfer, so that wax, resin, etc. were transferred onto the print medium by heating. The transfer film can be separated from the printing medium immediately after being heated, and an image of good quality can be formed.

The thermal print head is further provided with an electrically insulating circuit board having an electric wiring pattern formed of a conductive material on the surface thereof, and the head board is placed on the circuit board together with the driving IC. Since the main parts such as the common and individual electrodes and the heating resistors can be compactly formed on the head substrate by mounting, the cost of manufacturing the thermal print head can be reduced.

Further, the glaze layer is formed so as to have a flat portion that is substantially flat with respect to the upper surface of the head substrate and a convex portion that rises higher than the flat portion, so that the driving IC is provided for the heat generating region. It is possible to dispose wires, wires connected to them, a protective film covering them, and the like at a lower relative position.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a thermal print head according to the present invention will be described in detail according to embodiments with reference to FIGS. As shown in FIG. 1, the thermal print head according to the present embodiment has a head substrate 1 having a heating resistor formed on its upper surface and a circuit pattern made of a conductor on the surface for mounting the head substrate 1 together with a driving IC 2. It is a thin film type thermal print head composed of the formed circuit board 3. A heat radiating plate 4 made of a metal having a good thermal conductivity such as aluminum is mounted on the lower surface of the circuit board 3.

As shown in detail in FIG. 2, the head substrate 1 includes a head substrate 5 made of ceramic or the like, a glass glaze layer 6 as a heat storage member formed on the upper surface of the head substrate 5, and a thin film on the glaze layer. It is composed of a plurality of resistor films 7 formed in a strip shape, and a common electrode 8 and an individual electrode 9 formed on the resistor film 7 by a conductor in an opposing pattern.

The glaze layer 6 has a flat portion 6a whose surface extends substantially parallel to the surface of the head substrate 5, and a flat portion 6
It is composed of a convex portion 6b that is higher than a. On the glaze layer 6 on the side surface 14 side near the head base 5, as shown in FIG. 3A, the common electrodes 8 are formed in a convex shape with a constant pitch via the resistor film 7. While being formed toward the top of the portion 6b, a plurality of individual electrodes 9 are also formed toward the top of the convex portion 6b at the same pitch as that of the common electrode 8 so as to face them. Resistor film 7 between these common electrode 8 and individual electrode 9 facing each other
The so-called heat generating area 11 is constituted by
In the heat generating region 11 of the present embodiment, a common center line 12 extending between the common and individual electrodes 8 and 9 connects the top line on the surface of the convex portion of the glaze layer (the portion which rises highest with respect to the surface of the head substrate 5). It is provided so as to extend closer to the side surface 14 side of the head substrate 5 from the line 13. In this way, the common center line 12 of the heat generation regions 11 is provided so as to be offset from the top line 13 of the glaze layer convex portion, whereby each heat generation region 11 is formed.
It is possible to set the contact angle of the heat-sensitive medium which is brought into contact with and moved to these in the range of 0 to 30 °, for example.
A protective film 16 for covering and protecting the common and individual electrodes 8 and 9 and the resistor film 7 is further formed so that the common electrode 8 is exposed at the side end of the anti-heating resistor. . The convex portion 6b of the glaze layer 6 is replaced by the flat portion 6b.
It may be formed so that the thickness thereof decreases in an arc shape in a cross-sectional view toward the side surface 14 of the base body 5 without raising it higher than the surface of the base 5, in which case the heat generating region 11 is inclined in the arc shape. The top line 13 is provided on the flat portion 6 while being provided on the glaze layer.
It is defined as extending on the boundary on the surface of a and the arc-shaped convex portion 6b.

FIG. 3 (b) is a view similar to FIG. 3 (a) when the present invention is applied to a thick film type thermal print head. The common center line 12 is also the top line 1 of the convex portion 6a of the glaze layer 6.
3 is provided close to the side surface 14 of the head substrate 5. Referring again to FIG. 2, a metal layer 17 made of a conductive metal such as Al is formed on each side surface and bottom surface of the head substrate 5 so as to be electrically connected to the common electrode 8. Since the metal layer 17 is formed over the side surface and the bottom surface of the head substrate 5 in a state of being electrically connected to the common electrode 8 as described above, when the thermal print head is used, the common connection of the common electrode 8 is substantially made. Acts as a department. Since the head substrate 5 of this embodiment is covered with the conductive metal layer 17 covering the side surface and the bottom surface thereof,
It can be easily electrically connected to the circuit pattern of the circuit board 3 as shown in FIG. 1 by using a conductive adhesive containing silver particles or the like. The circuit board 3 can be mounted on the circuit board 3 by soldering, for example, by plating a metal film of Al with Ni instead of the conductive adhesive.

In the present embodiment, only the tip of the common electrode 8 (excluding the commonly connected common connection portion) is formed on the head base 5, and the common connection portion is provided on the side surface and the bottom surface. Although the case of forming the layer 17 is shown, instead of this, as shown in FIGS. 4A and 4B, the whole or a part of the common connecting portion is formed on the surface of the head substrate 5 together with the tip portion. Of course, it is possible. In addition, in FIG.
The same or similar parts or elements as in (a) and FIG. 3 (b) are indicated by the same numbers.

The metal layer 17 is formed so as to cover both the side surface and the back surface of the head substrate 5, but instead of this, the metal layer 17 is formed only on the side surface of the head substrate 5, and the metal film 17 on the side surface is formed.
May be connected to the circuit pattern of the circuit board 3. The head substrate 1 configured as described above is mounted on the circuit substrate 3 together with the driving IC 2, but the driving IC 2 mounted in this way is placed between the corresponding individual electrode 9 of the head substrate 1. Wire bonding and necessary wiring processing are performed with a conductor wire such as gold at
A protective film 18 is provided to cover and protect the driving IC 2 and the circuit pattern.

As described above, the thermal print head according to the present embodiment has the heat generating area 1 provided on the head substrate 1.
The common center line 12 of No. 1 is provided closer to the side surface 14 of the head base 5 than the top line 13 of the convex portion of the glaze layer, and the driving IC 2 is provided on the head substrate 1 on which the heat generation area 11 is formed. Are mounted on the circuit board 3 as separate bodies, the contact angle of the heat-sensitive medium that is moved in contact with each of the heat generation areas 11 (the head substrate 5 or the surface of the circuit board 3 and the tangent line of the contact portion of the platen roller). It becomes easy to set the angle formed by and within a range of 0 to 30 °, and high printing efficiency can be obtained even when forming a color image, and at the same time, the upper surface of the driving IC 2 and hence the wires connected to them. And the protective film 18 and the like covering them, the heat generating region 1
1, it is possible to provide a sufficiently low positional relationship with respect to 1. Therefore, as shown in FIG. 5, for application to color printing, using a single platen roller B, for example, yellow, magenta, In the case of forming an image with three colors of cyan, it becomes possible to easily provide the thermal print heads A _Y , A _M , and A _{C according} to the present invention with respect to the platen roller B at a contact angle of 0 to 30 °. It is possible to secure a large degree of freedom of arrangement.

Next, a method of manufacturing the thermal print head according to this embodiment will be described. First, a groove extending from the glaze layer to the inside of the substrate material is formed by a dicer from above the ceramic substrate material on which the glaze layer is formed on the upper surface and a plurality of head bases 5 can be formed, along a dividing line for division. After that, by heating to a temperature of about 850 ° C. for about 20 minutes, a flat portion 6a that spreads substantially parallel to the surface of the substrate material and a convex portion 6b that rises higher than the flat portion near the groove are formed.
It is possible to obtain a glaze layer in which and are formed. As described above, the glaze layer includes the convex portion 6b and the flat portion 6b.
It may be formed such that the thickness is reduced in an arc shape in a cross-sectional view toward the side wall of the groove without raising the height higher than the surface. On the glaze layer 6 having such a convex portion 6b, a resistor film containing tantalum nitride as a main component is formed to a layer thickness of about 0.1 μm by reactive sputtering, and a common electrode and an individual electrode are further formed thereon. After forming an Al film by sputtering for formation, A other than the common electrode and individual electrodes and the heat generation area is formed.
The I film and the resistor film are removed by etching, and then the Al film in the portion where the heat generating region is to be formed is removed by etching to form the heat generating region 11 including the common electrode 8, the individual electrode 9 and the resistor film 7. . When forming the common electrode 8, it is desirable to form only the tip portion other than the common connecting portion as described above, but it is also possible to form all or part of the common connecting portion together with the tip portion. Good. After forming the necessary common and individual electrodes 8 and 9 and the heat generation area 11 in this way, a protective film 16 for covering and protecting the exposed resistor film 7 of these electrodes and the heat generation area 11 is formed by S.
It is formed by stacking an iO ₂ film and a Ta ₂ O ₅ film,
The substrate material is divided into individual head substrates 5 along division lines to expose the exposed end 8a of the common electrode laterally.

Next, a metal film 1 made of a conductive metal such as Al so as to be electrically connected to the exposed end 8a of the common electrode.
7 are formed on each end surface and the back surface of the head substrate 5 by sputtering. The sputtering of the metal film 17 is performed from the back surface side of the head substrate 5, so that the metal particles are appropriately wrapped around each end surface side of the substrate, so that the end surface and the back surface of the head substrate 5 have an appropriate layer thickness, for example, about 2 μm. Is formed to a layer thickness of.

After forming the head substrate 1 as described above,
A circuit board 3 such as a ceramic having a circuit pattern formed of a conductor on its surface is mounted in an electrically connected state by using a conductive adhesive containing silver particles or the like, and at the same time, the circuit board 3
After mounting the drive IC 2 on top and making the necessary wiring, etc.,
Protective film 1 for covering and protecting these driving IC 2 and wiring
By forming No. 8, the thermal print head according to this embodiment can be obtained.

Although the metal layer 17 is provided on the end surface and the back surface of the substrate after forming the protective film in the above-mentioned embodiment, the present invention is not limited to this, and the common electrode 8 is formed on the common electrode 8 before forming the protective film 18. It may be formed on the end surface and the back surface of the head substrate 5 so as to be electrically connected, and then the protective film 18 may be formed on the front surface side and the end surface of the substrate in necessary regions.

[Brief description of drawings]

FIG. 1 is a side view of a thermal print head according to an exemplary embodiment of the present invention.

FIG. 2 is a sectional view of a head substrate of the thermal print head of FIG.

3 is an enlarged plan view of an essential part of the head substrate shown in FIG.

4 is an enlarged plan view of an essential part of a modification of the head substrate shown in FIG.

FIG. 5 is a diagram showing application of the thermal print head of the present invention to color image formation.

FIG. 6 is a side view of a conventional thermal printhead.

[Explanation of symbols]

 1 Head Substrate 2 Driving IC 3 Circuit Substrate 5 Head Substrate 6 Glaze Layer 7 Resistor Film 8 Common Electrode 9 Individual Electrode 10 Head Substrate Surface 11 Heat Generation Area 12 Common Centerline 13 Top Line 15 Thermosensitive Medium 17 Metal Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masatoshi Nakanishi, 21 Mizozaki-cho, Saiin, Ukyo-ku, Kyoto Rom Co., Ltd.

Claims (5)

[Claims] 1. A head substrate having a glaze layer formed on a surface thereof, a common electrode having a common connection portion formed on the head substrate and commonly connected, and an individual electrode formed corresponding to the common electrode. A heating resistor formed so that a heating area is provided between the corresponding common and individual electrodes, and a driving I electrically connected to the individual electrode.
And the common center line of the heat generation region is at a position closer to the end face of the head substrate than the top line on the surface of the glaze layer with respect to the upper face of the head substrate, and the upper surface of the driving IC. A thermal print head, which is formed so as to extend to a position higher than the above. 2. The thermal print head further includes an electrically insulating circuit board having an electric wiring pattern formed on the surface thereof with a conductive material, and the head board is provided on the circuit board together with the driving IC. The thermal print head according to claim 1, which is mounted on the. 3. The head substrate has a conductive layer electrically connected to the common electrode on at least one side surface thereof, and the common electrode is electrically connected to an electric wiring pattern of the circuit board via the conductive layer. The thermal print head according to claim 2, which is connected to the. 4. A protective film is formed on the upper surface of the head substrate to cover the heat generating region and the common and individual electrodes, and the conductive layer covers at least one side surface of the head substrate and a part of the protective film. 4. The thermal print head according to claim 3, which is electrically connected to the common electrode. 5. The glaze layer comprises a flat portion that is substantially flat with respect to the surface of the head substrate and a convex portion that rises higher than the flat portion, and the heat generating region is provided on the convex portion. Item 2. The thermal print head according to Item 1.