JPH05270030A - Thermal head - Google Patents

Abstract

PURPOSE:To enhance the printing yield of a thermal printer when a recording medium impossible to curve is used. CONSTITUTION:In a thermal head, a protruding plane 21 is formed on the surface of a head substrate 20 and a flat glaze layer 30 is formed on the plane 21. By this constitution, even when the position of the heating resistor 25 formed on the glaze layer 30 changes because of a production error, the close contact with a recording medium is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end face type thermal head for printing on a prepaid card or the like.

[0002]

2. Description of the Related Art At present, various types of printers have been put to practical use, for example, a thermal printer for printing on a prepaid card and the like. Therefore, as a first conventional example of a thermal head used in such a thermal printer, an apparatus disclosed in Japanese Patent Laid-Open No. 1-113262 will be described with reference to FIGS. 3 and 4. First, in this thermal printer 1, as illustrated in FIG. 3, an individual electrode 4 and a common electrode 5 are provided at both ends on a glass glaze layer 3 formed on the surface of a ceramic substrate 2 which is a head substrate. The integrally formed heating resistors 6 are connected by photolithography or the like, and the ceramic substrate 2 is attached to the end surface of a rectangular parallelepiped radiator plate 7. Here, a driver I, which is a drive circuit, is provided on the front surface of the heat sink 7.
A C (Integrated Circuit) 8 is mounted, and the driver IC 8 is connected to the TAB (Tape Tape) on the individual electrode 4 on the ceramic substrate 2 by a bonding lead 9 which is a wiring material.
Autometed Bonding). The protective cover 10 covering the driver IC 8, the bonding leads 9, the individual electrodes 4 and the like serves as the heat dissipation plate 7.
The thermal head 11 is formed by being attached to the.

In this thermal printer 1, as illustrated in FIG. 4, a platen roller 12 is pivotally supported at a position facing the heat generating resistor 6 exposed from the end surface of the protective cover 10 of the thermal head 11. A conveyance path for the ink ribbon 13 and the recording medium 14 is formed between the platen roller 12 and the ceramic substrate 2.

In such a structure, in the thermal printer 1, the heating resistor 6 is generated by selectively switching the driver IC 8 in accordance with the input print data.
The driving power is applied to the recording medium 14, and the recording medium 14 is conveyed by the rotation of the platen roller 12 in synchronization with the heating scanning of the heating resistor 6, so that the ink ribbon 1 is printed on the recording medium 14.
Image printing is performed by fusing the ink of No. 3.

Here, in the above-described thermal printer 1, by covering the connecting portion between the individual electrode 4 and the bonding lead 9 with the protective cover 10, it is possible to prevent the ink ribbon 13 and the recording medium 14 from coming into contact therewith. ing. But,
Since the protective cover 10 protrudes from the heating resistor 6, the recording medium 14 pressed by the platen roller 12 against the heating resistor 6 is bent at a step between the heating cover 6 and the protective cover 10, as illustrated in FIG. Will be done. That is, in this thermal printer 1, it is difficult to use a non-curvable prepaid card or the like as the recording medium 14.

As a thermal head that solves such a problem, there is an apparatus disclosed in Japanese Patent Laid-Open No. 60-21263. Therefore, this thermal head will be described as a second conventional example with reference to FIG. In this thermal head 15, a glass glaze layer 17 protruding in a cylindrical shape is formed on an end surface of a ceramic substrate 16, and a heating resistor 6 is formed on a flat surface having a width of 1.0 to 2.5 (mm) located at the apex thereof. ing. The other structure is the same as that of the thermal printer 1 described above.

With this structure, in the thermal head 15, even if the platen roller 12 is disposed so as to face the heating resistor 6 with the protective cover 10 attached so as to cover the individual electrode 4, the heating resistor 6 is also provided. Can be projected beyond the surface of the protective cover 10. Therefore, in the thermal head 15, it is possible to prevent the recording medium 14 from being bent by the platen roller 12 and pressed against the heating resistor 6, so that a non-curvable prepaid card or the like can be used as the recording medium 14. Is.

[0008]

In the thermal head 15 illustrated as the second conventional example, the heating resistor 6 formed on the apex of the cylindrical glass glaze layer 17 is projected from the surface of the protective cover 10. By doing so, an image can be printed on the recording medium 14 such as a prepaid card that cannot be curved.

However, this thermal head 15 is shown in FIG.
As illustrated in (a), FIG. 7 (a), and FIG. 8 (a), it is necessary to form the heating resistor 6 by photolithography or the like so as to be located on the apex of the curved surface of the glass glaze layer 17. Therefore, its productivity is low and it is difficult to improve the yield. That is, when the thermal head 15 having the above structure is actually manufactured, as illustrated in FIGS. 6B and 6C,
Due to manufacturing errors, the position of the heating resistor 6 may fluctuate in the sub-scanning direction and may not be located on the apex of the glass glaze layer 17. In this case, as illustrated in FIG. 7B and FIG. 8B, the heating resistor 6 separates from the recording medium 14 and print quality is degraded or printing becomes impossible. In order to print well with the head 15,
As illustrated in FIG. 7C, it is necessary to take measures such as inclining and positioning the thermal head 15 with respect to the recording medium 14. Further, in such a thermal head 15, as illustrated in FIG. 8C, the direction in which the heating resistors 6 continuously arranged on the apex of the glass glaze layer 17 change due to manufacturing error, The heating resistor 6 may be formed in a direction intersecting the apex line of the glass glaze layer 17. In order to perform good printing with such a thermal head 15, as illustrated in FIG. 9, it is necessary to take measures such as rotating and positioning the recording medium 14 as a whole in the transport direction. Even with this, since the heating resistor 6 is only partially located on the apex of the glass glaze layer 17, the print quality is continuously deteriorated in the main scanning direction.

The present invention is to obtain a thermal head in which performance deterioration due to manufacturing error is prevented.

[0011]

A glaze layer is formed on the surface of a head substrate which is elongated in the main scanning direction, and a large number of heating resistors each having electrodes formed in the sub scanning direction are formed on the surface of the glaze layer. In the thermal heads connected in the scanning direction, a flat surface was formed on the surface of the head substrate so as to project from both sides in the sub-scanning direction, and the glaze layer was formed flat on this flat surface.

[0012]

Since the heating resistor formed on the flat glaze layer has good adhesion to the recording medium even if the position fluctuates due to manufacturing error, deterioration of print quality and assemblability due to manufacturing error was prevented. A thermal head can be obtained.

[0013]

Embodiments of the present invention will be described with reference to FIGS. 1 and 2. First, the structure of the thermal head 19 of the thermal printer 18 will be described in detail below. The thermal head 19 is provided with flat surfaces 22 and 23 that are inclined on both sides in the sub-scanning direction of a flat surface 21 that projects from the center of the head substrate 20 that is elongated in the main scanning direction in the sub-scanning direction. A plane 24 parallel to the plane 21 is formed on one of the surfaces 22 and 23. Here, each of the planes 21 to 24 is extended in the main scanning direction of the head substrate 20, and a heating resistor 25 is formed on the plane 21 projecting from the others to form a common electrode on the planes 22 and 23. 26 and individual electrodes 27 are formed, and the electrodes 26, 26
It has a structure in which 27 terminal portions 28 and 29 are formed.

A specific example of the structure and manufacturing method of the thermal head 19 will be described below. First, the ready-made large-sized substrate made of alumina, ceramic, etc., obtained by firing a green sheet in advance, is subjected to polishing or cutting, or
The green sheet before firing is subjected to shape forming by polishing, die pressing, powder pressing, injection molding, or the like, and then firing, so that the multi-piece substrate of the head substrate 20 is mass-produced. Therefore, the glass glaze layer 30 is formed flat on the flat surface 21 of the head substrate 20 thus formed by the existing thin film technique and then washed, and thereafter, the heating resistor 25 is formed on the entire surface of the head substrate 20. A Ta—SiO ₂ layer and an Al layer to be the electrodes 26 and 27 are sequentially formed by sputtering or the like. Then, a photoresist is spin-coated thereon, and each thin film layer is patterned by a photolithography process, whereby the heating resistor 25 and the electrodes 26, 2 are formed.
7 are formed on each of the electrodes 26 by the existing thin film technology,
A protective film 31 is formed so as not to cover the terminal portions 28 and 29 of 27.

In the thermal head 19, for example, the flat surface 21 has a width of 7.0 (mm) in the sub-scanning direction, the glass glaze layer 30 has a width of 5.0 (mm) in the sub-scanning direction, and the head substrate 20 has a width in the sub-scanning direction. 15 (mm), the level difference between the flat surfaces 21 and 24 is 0.6
(mm) and the like, and by forming in such a shape, both productivity and print quality are good, as will be described later.

The thermal printer 18 has a structure in which the thermal head 19 having the above-described structure is mounted on the end surface of the heat dissipation plate 32, and the drive circuit is arranged on the side of the heat dissipation plate 32. Here, the heat dissipation plate 32 is formed to have a width smaller than that of the head substrate 20 of the thermal head 19 in the sub-scanning direction.
The edge portion on the 29 side projects from the side surface of the heat dissipation plate 32. Further, in the thermal printer 18, the terminal portions 28, 29 of the head substrate 20 protruding from the heat dissipation plate 32 are provided.
FPC (Flexible Printed Circuit) which is a flexible wiring material by thermocompression bonding of an anisotropic conductive film (not shown)
cuite Board 33 is connected, and this FPC33
Is bent at a substantially right angle and its lower end is fixed to the side surface of the heat dissipation plate 32 via the circuit board 34 and the spacer 35. Then, the heat dissipation plate 32 thus formed
Driver IC (Integrat), which is a mounting component of a drive circuit, which is die-bonded to the back surface of the FPC 33 and connected by a bonding wire 36 or the like in the gap between the FPC 33 and the FPC 33.
ed Circuit) 37 is located.

By doing so, in the thermal head 19, the FPC connected to the edge of the head substrate 20 is connected.
Bonding wire 36 protruding above 33 and driver I
C37 is prevented from coming into contact with the heat dissipation plate 32 to cause a short circuit, and the bonding wire 36 and the driver IC 37 do not protrude from the surface of the FPC 33, which contributes to downsizing and thinning of the thermal head 19. be able to.

Here, when the FPC 33 is separated from the heat dissipation plate 32 as described above, there is a concern that the FPC 33 may be bent due to stress from the side and the printed wiring may be broken. Therefore, this thermal printer 1
In FIG. 8, the driver IC 37 mounted on the FPC 33 is potted with a sealing material 38 such as resin, and the same sealing material 38 is applied to the side surface of the heat dissipation plate 32 to release the FP.
The C33 and the heat radiating plate 32 are joined by the sealing material 38 to ensure the strength. Further, the circuit board 34
Has a chip component 39 such as a capacitor mounted on the surface directly connected to the back surface of the FPC 33, and a printer controller (not shown) is connected to a connector 40 provided at the lower edge of the chip component 39. It is like this.

In such a structure, in the thermal printer 18, as in the above-described thermal printer 1, the heating resistor 25 is heated and scanned by the driver IC 37, and is conveyed by the rotation of the platen roller 12 in synchronization therewith. An image is printed on the recording medium 14.

Here, in this thermal printer 18,
The plane 21 on which the heating resistor 25 that actually prints on the recording medium 14 is located is the planes 22 to 24 located before and after it.
Since the recording medium 14 is more protruded than the recording medium 14, the recording medium 14 such as a plastic card can be conveyed in a straight line without being curved. The structure in which the heating resistor 25 of the thermal head 19 projects in this manner is realized by the planes 21 to 24 continuously formed on the head substrate 20, and the heating resistor 25 is formed on the planes 21 to 23. 25 and electrodes 4, 5
Since it is easy to form the thermal printer 1
In No. 8, the yield and productivity of the thermal head 19 are extremely good as compared with the thermal printer etc. exemplified as the second conventional example.

Here, the result of a comparative experiment conducted by the applicant of the present invention by actually making the thermal head 19 having the above-described structure will be described in detail below. First, in order to confirm the change in print quality depending on the width of the glass glaze layer 30 in the sub-scanning direction, the applicant has a width of the head substrate 20 in the sub-scanning direction of 15 (mm) and a protrusion height of the flat surface 21 of 0.6 (mm). , The width of the plane 21 in the sub-scanning direction is
7.0 (mm), the layer thickness of the glass glaze layer 30 is 60 to 80 (μm),
The width of the glass glaze layer 30 in the sub-scanning direction is 3.0, 2.5,
A 2.0, 1.5, and 1.0 (mm) thermal head 19 was prototyped.
In addition, in the thermal head 19, the heating resistor 25 is positioned substantially at the center of the glass glaze layer 30 having the width in the sub-scanning direction as described above.

Then, when these thermal heads 19 were assembled to the thermal printer 18 and the printing quality was compared, if the width of the glass glaze layer 30 in the sub-scanning direction is 1.5 (mm) or more, the printing quality is good, and the manufacturing It was confirmed that the print quality does not deteriorate even if the formation position of the heating resistor 25 changes in the sub-scanning direction due to an error. However, to be more precise, the thermal head 19 having a small width in the sub-scanning direction of the glass glaze layer 30 tends to affect the printing quality due to the assembling accuracy, and the thermal head 19 having a larger width in the sub-scanning direction ensures the printing quality and assembles. It was confirmed that it contributes to the improvement of sex. Further, when the end surface shape of the glass glaze layer 30 as described above is visually observed with a microscope, the width in the sub-scanning direction is 1.5 (mm).
Although the above glass glaze layer 30 is flat, the glass glaze layer 30 having a width in the sub-scanning direction of 1.0 (mm) is raised in a cylindrical shape. Due to such a difference in shape, print quality and assemblability are improved. It was confirmed to be different.

Next, the present applicant has found that the width in the sub-scanning direction is 1.5 (m
A flat surface 21 on which the glass glaze layer 30 of m) can be formed flat
In order to confirm the width in the sub-scanning direction of the head substrate 20, the head substrate 20 having the width in the sub-scanning direction of the flat surface 21 of 3.0, 2.5, 2.0, 1.2 (mm) was prototyped and the width in the sub-scanning direction was printed on the head substrate 20 by thick film printing. But
A glass glaze layer 30 of 1.5 (mm) was formed. Then,
Head substrate 2 in which the width of the plane 21 in the sub-scanning direction is 2.5 (mm) or more
At 0, it was confirmed that the flat glass glaze layer 30 was formed well, but the width of the plane 21 in the sub-scanning direction was 1.5.
In the head substrate 20 of (mm), it was confirmed that the glaze paste protruded in the sub-scanning direction due to a manufacturing error. In this case, the glass glaze layer 30 protruding from the flat surface 21 is
It has been found that it projects in an overhang shape at the boundary with the other planes 22 and 23 and causes disconnection of the electrodes 26 and 27 formed thereon. Further, the width of the plane 21 in the sub-scanning direction is
In the 2.0 (mm) head substrate 20, the glass glaze layer 30
However, it was confirmed that the yield was low.

That is, in the thermal head 19 in which the flat surface 21 on which the heating resistor 25 is formed is projected more than the flat surfaces 22 to 24 on both sides, the glass glaze layer 30 formed under the heating resistor 25 is in the sub-scanning direction. When the width is 1.5 (mm) or more, the surface of the glass glaze layer 30 is formed flat, the print quality and the assembling property are improved, and the glass glaze layer 30 having such a width in the sub-scanning direction is formed well. It was found that the width of the flat surface 21 in the sub-scanning direction needs to be 2.0 (mm) or more. In order to improve the yield more stably, the width of the flat surface 21 in the sub-scanning direction should be 3.0 (mm).
In addition to the above, it is desirable that the width of the glass glaze layer 30 in the sub-scanning direction is 2.0 (mm) or more.

It is also possible to form a protective cover on the FPC 33 located on the terminals 28 and 29 of the thermal head 19 by applying a resin material or the like (not shown). Further, as a method of connecting the FPC 33 and the terminal portions 28 and 29, in addition to thermocompression bonding of an anisotropic conductive film,
Thermal bonding with gold-gold, gold-solder, copper-solder, or the like, thermal bonding similar to TAB, or thermal bonding in combination with ultrasonic waves can be performed.

Further, in the thermal head 19 of this embodiment, the flat surface 22 lower than the flat surface 21 below the heating resistor 25 is formed by inclining to the position opposite to the terminals 28 and 29, so that it is conveyed linearly. This prevents the recording medium 14 from colliding with the edge of the thermal head 19. However, the present invention is not limited to the above structure, and as illustrated in FIG. 2A, the flat surfaces 42 and 43 lower than the flat surface 41 below the heating resistor 25 are provided only on the terminal portions 28 and 29 side. The thermal head 45 formed on the substrate 44, or, as illustrated in FIG. 2B, the heads via the flat surfaces 49 and 50, which are parallel to the flat surface 46 below the heating resistor 25 and are low flat surfaces 47 and 48 which are inclined on both sides. A thermal head 52 or the like formed on the substrate 51 can also be implemented.

In the thermal printer 18 of this embodiment, it is assumed that the flat surfaces 21 to 24 having the steps of the head substrate 20 are formed by extrusion molding, press molding using a die, or cutting. It is possible to implement a head substrate (not shown) in which a step is formed on the surface of the substrate with a thick film or the like, and a thermal head having such a structure is disclosed by the applicant in Japanese Patent Application No. 3-241385. ing. Further, in the thermal printer 18 of this embodiment, the lower end portion of the FPC 33 separated from the heat dissipation plate 32 is attached to the circuit board 34 and the spacer 35.
An example of fixing with and is shown, but such a spacer 3
It is also possible to form 5 together with the heat dissipation plate 32. Furthermore, in the thermal printer 18 of the present embodiment, it has been illustrated that the FPC 33, which is an expensive component, is shortened by connecting to the circuit board 34. However, such an FPC 33 and the circuit board 34 are implemented by one FPC. It is also possible.

[0028]

As described above, according to the present invention, a glaze layer is formed on the surface of a head substrate which is elongated in the main scanning direction, and a large number of heat generating elements are formed on the surface of the glaze layer in the sub scanning direction. In a thermal head in which a resistor is continuously provided in the main scanning direction, a flat surface is formed on the surface of the head substrate so as to project from positions on both sides in the sub scanning direction, and the glaze layer is formed flat on this flat surface. Since the heating resistor formed on this flat glaze layer has good adhesion to the recording medium even if the position fluctuates due to manufacturing error, thermal resistance that prevents deterioration of print quality and assembling due to manufacturing error. It is possible to obtain a head and the like.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of the present invention.

FIG. 2 is a vertical sectional side view showing a modified example.

FIG. 3 is a perspective view showing a first conventional example.

FIG. 4 is a vertical sectional side view.

FIG. 5 is a perspective view showing a second conventional example.

FIG. 6 is a schematic side view showing a thermal head in which a manufacturing error has occurred.

FIG. 7 is a side view showing a thermal printer.

FIG. 8 is a perspective view.

FIG. 9 is a side view.

[Explanation of symbols]

 19, 45, 52 Thermal head 20, 44, 51 Head substrate 21, 41, 46 Plane 25 Heating resistor 30 Glaze layer

Claims (1)

[Claims] 1. A glaze layer is formed on the surface of a head substrate which is elongated in the main scanning direction, and a large number of heating resistors each having electrodes formed in the sub scanning direction on the surface of the glaze layer are connected in the main scanning direction. In the provided thermal head, a flat surface is formed on the surface of the head substrate so as to project from positions on both sides in the sub-scanning direction, and the glaze layer is formed flat on this flat surface.