JPH07290740A - Thermal head - Google Patents

Abstract

PURPOSE:To provide a lightweight inexpensive long thermal head capable of forming a specific sharp and high printing image on thermal paper. CONSTITUTION:In a thermal head constituted by arranging and fixing a plurality of ceramics substrates 1 each having a large number of heating elements 2 provided on the upper surface thereof on a support plate 4 and attaching the support plate 4 to the upper surface of a rectangular parallelepiped radiation member 5 made of aluminum and performing printing by allowing thermal paper to slide on a large number of the heating elements 2, the support plate 4 is formed of an iron alloy and the end part crossing the slide contact direction A of the thermal paper at a right angle is bent so as to come into contact with the side surface of the radiation member 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head incorporated as a printer mechanism for a word processor or the like, and more particularly to a long thermal head in which a plurality of ceramic substrates provided with a large number of heating elements are arranged. .

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for a long thermal head as a printer mechanism such as a word processor.

Such a conventional long thermal head is shown in FIG.
As shown in (a) and (b), a plurality (for example, three) of ceramic substrates 11 made of alumina ceramics having a large number of heating elements 12 made of tantalum nitride or the like provided on the upper surface,
The heat radiating plates 13 are arranged on the aluminum heat radiating plate 13, and the heat radiating plates 13 and the plurality of ceramic substrates 11 are fixed by a silicon adhesive or the like. Predetermined electric power is applied based on the print signal to selectively cause the heating element 12 to generate Joule heat, and the generated heat is conducted to the thermal paper conveyed by the platen roller 14 to produce a predetermined print image on the thermal paper. To function as a thermal head.

The heat dissipation plate 13 is the ceramic substrate 1
This is for conducting and absorbing a part of the heat of 1 to maintain the ceramic substrate 11 at a temperature suitable for printing.
It is formed with a thickness of 10 to 30 mm.

[0005]

However, in this conventional long thermal head, the thermal expansion coefficient of the heat dissipation plate 13 forming the heat dissipation plate 13 is 2.35 × 10 ⁻⁵ / ° C.
Since the coefficient of thermal expansion (0.7 × 10 ⁻⁵ / ° C.) of alumina ceramics forming the ceramic substrate 11 is extremely large and the ceramic substrate 11 is directly attached to the heat dissipation plate 13, When the thermal head is heated to a high temperature by the heat generated by the heating element 12 during printing, a large gap is formed between the adjacent ceramic substrates 11 due to a large difference in the coefficient of thermal expansion between the ceramic substrate 11 and the heat dissipation plate 13. As a result, there is a drawback that white stripes are formed on the thermal paper or the like due to the gap.

Further, as described above, when the coefficient of thermal expansion of the ceramic substrate 11 and the heat radiating plate 13 to which the ceramic substrate 11 is directly attached are largely different, an external force is applied by the platen roller 14 during printing. Then, the heat dissipation plate 13 is easily displaced in the direction orthogonal to the arrangement direction of the ceramic substrates 11, and the heating element 12 cannot be brought into good contact with the thermal paper or the like, and as a result, it is clear on the thermal paper or the like. It has a drawback that it is impossible to form a clear printed image.

Therefore, in order to solve the above drawbacks, the heat sink 1
It is conceivable that 3 is made of an iron alloy and the coefficient of thermal expansion of the heat dissipation plate 13 is made substantially equal to the coefficient of thermal expansion of the ceramic substrate 11.

However, when the heat dissipation plate 13 is made of an iron alloy, the iron alloy is relatively expensive and has a large specific gravity. Therefore, if the heat dissipation plate 13 for a long thermal head is formed with a large volume of about 10 to 30 mm, the thermal head as a product becomes expensive and the total weight of the thermal head becomes extremely large. In order to support the large thermal head in the printer device, a strong supporting means for the frame is required, and the printer device has a disadvantage of being large in size.

[0009]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned drawbacks, and an object thereof is a lightweight and inexpensive long thermal head capable of forming a clear and excellent predetermined printed image on a thermal paper or the like. To provide.

[0010]

In the thermal head of the present invention, a plurality of ceramic substrates having a large number of heating elements on the upper surface thereof are arranged and fixed on a support plate, and the support plate is made of rectangular parallelepiped aluminum. A thermal head which is mounted on a heat dissipating member, prints by sliding thermal paper or the like on the large number of heat generating elements, wherein the support plate is made of an iron alloy, and It is characterized in that the end of the thermal paper or the like orthogonal to the sliding contact direction is bent so as to abut the side surface of the heat dissipation member.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1A is a perspective view showing an embodiment of a thermal head according to the present invention, FIG. 1B is a sectional view taken along line XX of FIG. 1A, and 1 is a ceramic substrate. Reference numeral 2 is a heating element, 3 is a driving IC, 4 is a support plate, and 5 is a heat dissipation member.

The ceramic substrate 1 is made of alumina ceramics. For example, ceramic material powder such as alumina, silica, magnesia, etc. is mixed with an appropriate organic solvent and solvent to form a sludge, and this is formed by a well-known doctor blade method. To form a ceramic green sheet, and then the ceramic green sheet is punched into a predetermined shape and at a high temperature (about 16
It is manufactured by firing at 00 ° C.

On the upper surface of the ceramic substrate 1, a large number of heating elements 2 linearly arranged and a pair of conductive layers connected to the heating elements 2 are provided.

The heat generating element 2 is made of, for example, tantalum nitride or the like and has a predetermined electric resistivity, so that Joule heat is generated when electric power is applied through the pair of conductive layers. Heat is generated at a temperature required to form a printed image on a recording medium, for example, a temperature of 200 to 350 ° C.

The heating element 2 is deposited and formed on the ceramic substrate 1 by adopting the conventionally known sputtering method and photolithography technique.

The pair of conductive layers connected to the heating element 2 are made of aluminum or the like, and the conductive layers have a function of applying a predetermined electric power required to cause Joule heating in the heating element 2. Do

A plurality of driving ICs 3 are also mounted on the upper surface of the ceramic substrate 1 by face down bonding or the like, and the driving ICs 3 make the plurality of heating elements 2 correspond to an external electric signal. It has a function of selectively causing Joule heat generation, specifically, a function of controlling on / off of electric power applied to each heating element 2 through the pair of conductive layers.

A plurality of (for example,
3 pieces), which are arranged linearly and have a thin support 4 (thickness: 1.0 mm to 2.0) through the silicone adhesive 7 and the instant adhesive (cyanoacrylate adhesive) 8.
mm) fixed above.

The support 4 has a function of supporting a plurality of ceramic substrates 1 on its upper surface and absorbing a part of heat of the ceramic substrate 1 to conduct the heat to the support 4 described later.

The support 4 is also made of an iron alloy such as F.
e-Ni (42Ni: an alloy of iron and nickel containing 42% of Ni in a composition ratio of 42%), and both end portions orthogonal to the sliding contact direction A of the thermal paper or the like have an aluminum heat dissipation member described later. It is bent downward so as to come into contact with the side surface of No. 5.

Fe-Ni (42) forming the support 4
Ni) has a thermal expansion coefficient of 0.7 × 10 ⁻⁵ / ° C., which is very close to the thermal expansion coefficient (0.7 × 10 ⁻⁵ / ° C.) of the alumina ceramics forming the ceramic substrate 1. Even if the thermal head is heated to a high temperature by the heat generated by the element 2 and the ceramic substrate 1 and the support body 4 are respectively thermally expanded, no large gap is formed between the adjacent ceramic substrates 11, and white stripes are formed on the thermal paper. It is possible to form a good printed image with no image.

The support 4 is made of Fe having a coefficient of thermal expansion close to that of the alumina ceramics forming the ceramic substrate 1.
-Ni (42Ni), and since the end portion of the thermal paper or the like orthogonal to the sliding contact direction A is bent downward so as to come into contact with the side surface of the aluminum heat dissipation member 5, the thermal paper or the like can be printed at the time of printing. Even if an external force is applied by the platen roller 9 that is conveyed onto the heating element 2, the support 4 is orthogonal to the arrangement direction of the ceramic substrates 1 due to the bent portion of the support 4 that contacts the side surface of the aluminum heat dissipation member 5. Effectively prevent trying to shift the position in the direction,
The heating element 2 provided on the ceramic substrate 1 can be fixed at a position where it can be always brought into good contact with a thermal paper or the like. This makes it possible to form a clear printed image on a thermal paper or the like for a long period of time.

Further, if the support 4 has a thickness of 2 mm or less, the bending process for forming the bent portion can be simplified and the long thermal head can be reduced in weight. Becomes Therefore, the support 4 is
It is preferable that the thickness is 2 mm or less.

The support plate 4 is manufactured by processing an iron alloy into a predetermined shape by using a conventionally known metal processing method.

In order to bond the ceramic substrate 1 onto the support 4, first, the three ceramic substrates 1 having a large number of heating elements 2 on the upper surface are attached to the ceramic substrate 1.
While the silicone adhesive 7 is applied to the entire lower surface of the substrate 4, the support 4 is placed and arranged at a predetermined position on the upper surface of the support 4, and then the instantaneous adhesive 8 is applied between the periphery of the ceramic substrate 1 and the support 4. , By leaving it for a predetermined time.

The support 4 to which the three ceramic substrates 1 are fixed also has a rectangular parallelepiped aluminum heat radiating member 5 (thickness: 10 to 30 mm) via a silicone adhesive or the like.
It is attached to the top.

The aluminum heat dissipating member 5 supports the support body 4 to which the ceramic substrate 1 is fixed on the upper surface thereof, and at the same time, a part of the heat of the ceramic substrate 1 is conducted and absorbed through the support body 4 to form a ceramic. This serves to maintain the temperature of the substrate 1 at a temperature suitable for printing.

Since the heat dissipation member 5 is formed of aluminum which is relatively inexpensive and has a small specific gravity, even if the heat dissipation member 5 is formed with a large volume, the thermal head as a product does not become so expensive. Also, the weight of the thermal head can be reduced. Therefore, the sturdiness supporting means and the like used to support the long thermal head in the printer are not required at all, and the printer can be downsized.

The heat radiating member 5 is manufactured by forming an ingot (lump) made of aluminum into a predetermined rectangular parallelepiped shape by using a conventionally known metal working method.

Thus, in the thermal head of the present invention, a predetermined electric power is applied to the heating element 2 as the driving IC 3 is driven to selectively cause the heating element 2 to generate Joule heat, and the generated heat is applied to the platen roller 9. It functions as a thermal head by forming a predetermined print image on the thermal paper or the like by conducting it to the thermal paper or the like conveyed by.

The present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the spirit of the present invention.

[0033]

In the thermal head of the present invention, a plurality of ceramic substrates having a large number of heating elements on the upper surface thereof are arranged and fixed on a supporting plate, and the supporting plate is mounted on a rectangular parallelepiped aluminum heat radiating member. A thermal head which is made by attaching and printing thermal paper or the like on the plurality of heating elements in sliding contact, wherein the support plate is made of an iron alloy, and is arranged in the sliding direction of the thermal paper or the like. Since the edges that intersect at right angles are bent so as to contact the side surface of the aluminum heat dissipation member, the coefficient of thermal expansion of the support plate becomes close to that of the ceramic substrate, and the thermal head heats up due to the heat generated by the heating element during printing. Even if the ceramic substrate and the support plate are thermally expanded, a large gap is not formed between the adjacent ceramic substrates, and the thermal paper has good white marking without white lines. Images can be formed.

In the thermal head of the present invention,
Since the support plate and the ceramic substrate have a thermal expansion coefficient close to each other, and the end portion of the support plate orthogonal to the sliding direction of the thermal paper or the like is bent so as to contact the side surface of the aluminum heat dissipation member, printing is performed. Even if an external force is applied by a platen roller that conveys thermal paper or the like onto the heating element, the bent portion of the support plate that is in contact with the side surface of the aluminum heat dissipation member causes the support plate to move in a direction orthogonal to the array direction of the ceramic substrates. It is possible to effectively prevent the positional deviation from occurring, and it is possible to fix the heating element on the ceramic substrate at a position where it can be always brought into good contact with the thermal paper or the like. This makes it possible to form a clear printed image on a thermal paper or the like for a long period of time.

Further, in the thermal head of the present invention,
Since the heat dissipation member is made of aluminum that is relatively inexpensive and has a low specific gravity, the thermal head as a product does not become expensive even if the heat dissipation member is formed in a large volume, and the thermal head is lightened. be able to. Therefore, the sturdiness supporting means and the like used to support the long thermal head in the printer are not required at all, and the printer can be downsized.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a thermal head of the present invention.

2A is a sectional view taken along line XX of FIG. 1, and FIG. 2B is FIG.
3 is a sectional view taken along line YY of FIG.

FIG. 3A is a perspective view of a conventional thermal head,
(B) is a sectional view taken along line XX of (a).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ceramic substrate 2 ... Heating element 3 ... Driving IC 4 ... Support plate 5 ... Heat dissipation member 7 ... Silicone adhesive 8 ... Instant adhesive 9 ... Platen roller

Claims (1)

[Claims] 1. A plurality of ceramic substrates having a large number of heating elements provided on an upper surface thereof are arranged and fixed on a supporting plate, and
A thermal head which is formed by attaching the support plate to a rectangular parallelepiped aluminum heat radiating member, and performs printing by sliding thermal paper or the like on the plurality of heat generating elements, wherein the support plate is an iron alloy. A thermal head, which is formed and is bent so that an end portion of the thermal paper or the like orthogonal to the sliding contact direction is in contact with the side surface of the heat dissipation member.