JPH11105319A - Thermal head and ink transfer printer using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal head having a high thermal efficiency and a quick thermal responsiveness by a constitution wherein a conductive member having both ends to which a voltage is applied is supported by a supporting substrate, and a narrowed section of which cross section is smaller than that of the other is form at a predetermined position in the conductive member, thereby making the resistance partially greater than that of the other section. SOLUTION: A plurality of conductive members 30 each formed to be elongated in a lateral direction are arranged in a vertical direction on a thermal head 3 which is supported by a supporting substrate 33 made of ceramics. The conductive members 30 are so constituted that each of the both ends of each conductive member 30 has a width greater than the other and each of the central sections has a width smaller than the other. The narrow section in the central portion is to be a heating section 31 serving as a heating resistor and wide sections in both ends are to be conductive sections 32 serving as lead members for applying a voltage to the heating section 31. As the cross section of the heating section 31 is made smaller and the resistance is made greater, it is possible to effectively heat the heating section 31, thereby improving the thermal responsiveness of the thermal head 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thermal head for forming an image by heating a recording medium in accordance with image information in a printer or the like.

[0002]

2. Description of the Related Art Conventionally, there has been known a thermal head for forming an image by heating a recording medium in accordance with image information in a printer or the like. FIG. 7 shows the structure of a conventional thermal head. The thermal head 5 is provided with a heat resistance layer (glass layer) 54 on a support substrate 53 and a heating element 51 on the surface thereof.
And a pair of lead wires 52 is fixed to the heating element 51. The heating element 51 and the lead wires 52 are covered with a protective layer 55.

In recent years, in order to speed up image formation, a thermal (heating / cooling) response to application of a voltage is fast,
A thermal head having high thermal efficiency is desired.

In particular, the applicant of the present invention arranges a film having a through hole and a thermal head so as to face each other, holds ink between the two, and makes a recording paper adhere to the opposite side of the thermal head across the film. Has proposed an ink transfer printer which is configured so that ink heated by a thermal head is transmitted through a through-hole and transferred to a recording sheet (Japanese Patent Application No. Hei 9 (1998) -209).
-96548). In such an ink transfer printer, since ink or a film is interposed between the recording paper and the thermal head, higher thermal efficiency and higher-speed response are required than a thermal printer (where the recording paper is in contact with the thermal head). .

[0005]

However, in the conventional thermal head 5 shown in FIG. 7, there is a heat transfer loss at the joint between the lead wire 52 and the heating element 51. That is, there is a problem that the applied voltage to the heating element is reduced due to the contact resistance at the joint, and the thermal response is slow due to the thermal resistance at the joint.

The present invention has been made in view of the above problems, and has as its object to provide a thermal head having high thermal efficiency and high thermal response.

[0007]

In order to solve the above-mentioned problems, a thermal head according to the present invention includes a conductive member to which a voltage is applied at both ends, and a support substrate that supports the conductive member. A configuration in which a constricted portion having a smaller cross-sectional area than other portions is formed at a predetermined portion of the conductive member to locally increase the resistance value, so that heat is generated in the constricted portion by a voltage applied to the conductive member. It was done.

According to this structure, the heat-generating portion (constriction) and the portion for applying a voltage to the heat-generating portion can be constituted by one member. Therefore, it is possible to eliminate a heat transfer loss such as a joint between a heating element and a lead wire of a conventional thermal head. That is, the thermal efficiency can be improved accordingly, and the thermal response to the application of the voltage can be accelerated. Further, since the joining operation (for the heating element and the lead wire) is not required, the manufacturing process of the thermal head is also simplified.

If a protective layer is further provided to cover the constricted portion of the conductive member, the constricted portion can be prevented from being damaged. Further, if a heat resistance layer is further provided between the constricted portion of the conductive member and the support substrate, it is possible to prevent the heat generated in the constricted portion from diffusing through the support substrate. Furthermore, it is also possible to configure a line head by arranging a plurality of conductive members on a support substrate in a line. in this case,
If one end of the conductive member is connected to form a common terminal, the configuration of the head becomes simpler.

Further, in the ink transfer printer according to the present invention, a film having a predetermined through hole and a thermal head are arranged to face each other, an ink space for holding ink is provided between the film and the thermal head, and the film is sandwiched. Then, the recording paper is brought into close contact with the side opposite to the thermal head, and the ink heated by the thermal head is transmitted through the through-hole and transferred to the recording paper.

In such an ink transfer printer in which ink is interposed between the recording paper and the thermal head, it is necessary to consider the spread of ink due to air bubbles, bleeding during transfer, and the like. Desirably smaller than the dots. In the thermal head according to the present invention, the heat generation area can be reduced as much as possible in manufacturing due to the shape of the constricted portion of the conductive member. Therefore, the printing dots can be reduced accordingly, and the printer can be made finer.

[0012]

FIG. 1 is a plan view showing the structure of a thermal head according to an embodiment. The thermal head 3
A plurality of conductive members 30 formed long in the horizontal direction in the figure are arranged in the vertical direction in the figure. The conductive member 30 has a wide width at both ends and a narrow width at the center. The constricted portion at the center becomes a heat generating portion 31 (described later) which functions as a heat generating element, and the wide portions at both ends become conductive portions 32 which function as lead members for applying a voltage to the heat generating portion 31.

One end (the right end in the figure) of the conductive portion 32 is integrally connected to each other to form a common terminal 36.
The other end (left end in the figure) of the conductive portion 32 is connected to a control circuit 38.
It is connected to the. The control circuit 38 controls the energization of the conductive part 32 according to the desired image information (IC or the like). The width of the common terminal 36 can be increased as necessary to prevent a voltage drop.

FIG. 2 is a side sectional view showing the structure of the thermal head 3. The thermal head 3 is held by a support substrate 33 which is a substrate made of ceramics. Also,
The heat generating part 31 of the conductive part 32 is covered with a protective film 35. That is, the thermal head 3 is
3, a conductive portion 32 and a protective film 35. In FIG. 1, the protective film 35 is not shown.

As shown in FIG. 1, the heat generating portion 31 has the smallest cross-sectional area (cross-sectional area in a direction orthogonal to the longitudinal direction of the conductive member 30) of the conductive member 30, and therefore has a large electric resistance. Therefore, when a voltage is applied to both ends of the conductive member 30, that is, the conductive portion 32 by the control circuit 37, the heat generating portion 31 generates relatively large resistance and generates heat.

In the conventional thermal head 5 (FIG. 7), the applied voltage to the heating element 51 is reduced due to the contact resistance at the junction between the lead wire 52 and the heating element 51, and the thermal resistance at the joining section is reduced. Therefore, there is a problem that the thermal response is slow. On the other hand, in the thermal head 3 of the present embodiment, since the heat generating portion 31 and the conductive portion 32 for applying a voltage to the heat generating portion 31 are formed by one member, the heat generation in the conventional thermal head is performed. There is no joint between the body and the lead wire. Therefore, the thermal efficiency can be improved, and the thermal response to the application of the voltage can be accelerated. Further, since the joining operation is unnecessary, the production of the thermal head 3 is simplified.

As shown in FIG. 3, when a heat resistance layer 39 made of glass or the like is provided between the heat generating portion 31 of the conductive portion 32 and the support substrate 33, heat generated in the heat generating portion 31 is generated. The diffusion along the support substrate 33 can be prevented. Further, the protective film 35 in FIG. 2 can be omitted.

Next, an ink transfer printer using the thermal head 3 will be described. FIG. 4 is a side sectional view showing a basic configuration of the ink transfer printer of the embodiment. In the ink transfer printer, a film 2 having a predetermined through hole (described later) and a thermal head 3 are bonded via a spacer 8. Thermal head 3 and film 2
Is provided with a gap of about 0.1 mm.

The spacer 8 and the support substrate 33 of the thermal head 3 are formed of a material that does not allow ink to pass therethrough.
An area surrounded by the spacer 8, the support substrate 33, and the film 2 becomes an ink space 1 for holding ink. The film 2 and the heat generating portion 3 of the thermal head 3
Slightly away from or in contact with 1. On the left side of the spacer 8 in the drawing, an ink container 10 for replenishing the ink space 1 with ink is provided. The ink in the ink container 10 is drawn into the ink space 1 by a capillary phenomenon through a communication hole 85 formed in the spacer 8.

Above the film 2, a platen roller 4 for bringing the recording paper P into close contact with the upper surface of the film 2 is provided. The platen roller 4 is a so-called rubber roller, and is disposed so that its axial direction matches the arrangement direction of the heat generating portions 31 of the thermal head 3. When the platen roller 4 rotates, traction acts between the platen roller 4 and the recording paper P, and the recording paper P is transported in the direction of the arrow in the figure.

FIG. 5 is an exploded perspective view of a portion excluding the platen roller 4 of the ink transfer printer. The spacer 8 is a thin plate having a rectangular opening 82. When the spacer 8 is attached to the thermal head 3,
1 is located below the opening 82. A large number of through holes 25 are formed in the film 2 in two rows. The film 2 is formed with the spacers 8 so that the through holes 25 are located above the respective heat generating portions 31 of the thermal head 3 and the arrangement direction of the through holes 25 matches the arrangement direction of the heat generating portions 31. Pasted on top.

FIG. 6 is a schematic diagram showing the image forming principle of the ink transfer printer. 6, the ink container 10 and the platen roller 4 are omitted. In the normal state of FIG. 6A, the inner diameter of the through hole 25 of the film 2 is set to a size that does not allow ink to pass through. Here, when the heat generating portion 31 generates heat, the ink near the heat generating portion 31 and the heat generating portion 3 are generated.
The film 2 almost in contact with 1 is heated. And
As shown in FIG. 6B, the ink heated by the heat generating portion 31 evaporates and expands, and a local pressure is generated in the ink by the vapor pressure. At the same time, the heated portion of the film 2 has a reduced elastic modulus due to the heat and is easily deformed.

Thus, the ink is pushed into the through hole 25 of the film 2 by the above pressure, and the ink is pushed into the through hole 2 of the film 2.
5 is spread. Then, the ink passes through the through holes 25 of the film 2 and is transferred to the recording paper P (FIG. 4) which is in close contact with the upper surface of the film 2. After the transfer, the heat generating part 31
Ink and film 2
Is heated by the surrounding ink, and the through hole 25 of the film 2 has the original size (a size that does not allow the ink to pass through).
Return to Therefore, in FIG. 4, a two-dimensional ink image is formed on the recording paper P by controlling the heat generation of the thermal head 3 in accordance with desired print information and controlling the rotation of the platen roller 4 to sequentially transport the recording paper P. can do.

In such an ink transfer printer in which ink is interposed between the recording paper P and the thermal head 3, it is necessary to consider the spread of ink due to air bubbles and the bleeding at the time of transfer. It is desirable that the size be smaller than the print dot. In the printer according to the present invention,
Due to the shape of the constricted portion (heat generating portion 31) of the conductive member, the heat generating area can be reduced as much as possible in manufacturing. Therefore, the printing dots can be reduced accordingly, and the printer can be made finer.

As described above, according to the thermal head of this embodiment, the heat-generating portion and the conductive portion (corresponding to the lead wire) are constituted by one member, so that the heat transfer loss can be eliminated. That is, the thermal efficiency of the printer can be improved, and the thermal response to the application of the voltage can be sped up. Thus, the image forming speed of the printer can be increased.

[0026]

As described above, according to the ink transfer printer of the present invention, a conventional thermal printer is constructed by forming a heat generating portion and a conductive member for applying a voltage to the heat generating portion with one member. The joint between the lead wire and the heating element, which was present in the head, is eliminated. Therefore, a reduction in the applied voltage to the heating element due to the contact resistance of the joint and a decrease in the thermal response due to the thermal resistance of the joint are prevented. That is,
The thermal efficiency can be improved, and the thermal response to application of a voltage can be accelerated.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating a structure of a thermal head according to a first embodiment.

FIG. 2 is a sectional view showing the structure of the thermal head of FIG.

FIG. 3 is a plan view showing another example of the thermal head of the first embodiment.

FIG. 4 is a sectional view showing a basic configuration of an ink transfer printer using the thermal head of FIG. 1;

FIG. 5 is a perspective view showing a main part of the ink transfer printer of FIG.

6 is a diagram illustrating the principle of image formation by the ink transfer printer of FIG.

FIG. 7 is a sectional view showing the structure of a conventional thermal head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink space 2 Film 3 Thermal head 4 Platen roller 25 Through hole 30 Conductive member 31 Heat generation part (constriction part) 32 Conduction part 33 Support substrate 35 Protective film 36 Common terminal 38 Control circuit

Claims (6)

[Claims] A conductive member that is formed to be long in a certain direction and has a voltage applied to both ends thereof; and a support substrate that supports the conductive member, wherein the conductive member is provided at a predetermined position of the conductive member. A thermal head configured to form a constricted portion having a smaller cross-sectional area in a cross section orthogonal to a direction than other portions, and to generate heat in the constricted portion by a voltage applied to the conductive member. 2. The semiconductor device according to claim 1, further comprising a protective layer covering at least a constricted portion of the conductive member.
The thermal head according to 1. 3. The thermal head according to claim 1, further comprising a heat resistance layer provided between the constricted portion of the conductive member and the support substrate. 4. The thermal head according to claim 1, wherein a plurality of said conductive members are arranged in a line on said support substrate to form a line head. 5. The thermal head according to claim 4, wherein one end of the conductive member is connected to each other to form a common terminal. 6. A film having a predetermined through-hole and the thermal head are arranged to face each other, an ink space for holding ink is provided between the film and the thermal head, and the thermal head is interposed between the film and the thermal head. 6. The thermal head according to claim 1, wherein a recording paper is brought into close contact with the opposite side, and the ink heated by the thermal head is transmitted through the through hole of the film and transferred to the recording paper. Ink transfer printer.