JPH0584225B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thermal head in which a preheating heater is formed in a part of the substrate in order to improve printing characteristics.

[Conventional technology]

Conventionally, as a thermal head having a preheating heater, a device as shown in FIG. 14 is known. In the figure, 1 is a substrate, 2 is a heat generating resistor formed on the substrate 1, 3 is an individual electrode that selectively drives this heat generating resistor 2, 4 is a common electrode, and 5 is a heat generating resistor 2 as well. , a heater for preheating formed on the substrate 1, and 6 a heater electrode for supplying current to the heater 5 for preheating. The preheating heater 5 is formed at the same time as the heating resistor 2 is formed.

In the thermal head configured in this way, by driving the preheating heater 5,
The temperature of the substrate 1 can be kept constant to eliminate printing unevenness, and a thermal bias can be applied to the heating resistor 2 to reduce the drive current supplied to the heating resistor 2 during the printing operation.

[Problem that the invention seeks to solve]

However, in such a thermal head, since the individual electrodes 3 and the common electrode 4 are arranged near the heating resistor 2, it is not possible to arrange the preheating heater 5 near the heating resistor 2. Can not. Therefore, although the preheating heater 5 can be used to control the temperature of the entire substrate 1, there is a large time delay in heat transfer to the heating resistor 2, and it is necessary to use a thermal bias or start to increase the printing speed. It is difficult to use it to control the substrate temperature during startup.

Additionally, in general, the heating resistor 2 is attached to the substrate 1 in order to facilitate installation of the thermal head in the printer.
In such cases, the preheating heater 5 cannot be formed on the substrate 1, and the preheating heater 5 is an external type that utilizes the heat dissipation of the transistor. heater must be used.

The present invention eliminates the drawbacks of the conventional apparatus as described above, allows the preheating heater to be placed near the heating resistor, and increases the printing speed due to the thermal bias effect of the heating resistor. The purpose of this invention is to realize a thermal head with a simple configuration that can quickly control the temperature of the substrate and prevent print quality from deteriorating during startup.

[Means for solving problems]

In the thermal head of the present invention, a plurality of electrode layers are successively stacked on one surface of a substrate so as to face each other with a glass layer serving as an electrical insulating layer and a thermal resistance layer interposed therebetween, and each layer including the substrate is formed in a straight line. cut,
A heating resistor and a preheating heater are formed on the exposed end face of each electrode layer.

[Effect]

In this way, when the end of the substrate is cut and the heating resistor and the preheating heater are formed on the exposed end face of the electrode layer, the electrode layer is formed on the end face where the heating resistor and the preheating heater are formed. Since the exposed area of the heater is small, the preheating heater can be placed near the heating resistor. Therefore, the heat transfer time between the preheating heater and the heating resistor is shortened, and the printing speed can be increased due to the thermal bias effect of the heating resistor, and the temperature of the substrate can be quickly controlled. It is possible to prevent print quality from deteriorating at startup.

〔Example〕

Now, the thermal head of the present invention will be explained below. Among these, a vertical thermal head in which the end of the substrate is cut off and a heating resistor is formed on the exposed end face of the electrode layer will be described below. The applicant has already filed an application as Japanese Patent Application No. 59-213116.

FIGS. 2 to 9 explain the manufacturing process of such a vertical thermal head in order. In the figure, the same parts as in FIG. 14 are designated by the same reference numerals. FIGS. 2 and 3 are steps for forming a first electrode layer on the substrate 1. FIG. The substrate 1 is, for example, a ceramic substrate, and a conductive material such as gold (Au), silver palladium, platinum, copper, etc. is printed and fired on its surface to form a conductive layer 30 as shown in FIG. The conductor layer 30 shown in the figure is one in which individual electrodes are integrally formed to be connected to each of the heating resistors arranged in a row, and are later etched into a pattern as shown in FIG. An electrode layer 3 (hereinafter referred to as individual electrode layer 3) is formed. Here, etching is used to process fine patterns when obtaining an electrode density of 10 lines/mm or more, and when the density is relatively low, an electrode pattern as shown in Figure 3 is directly formed by printing. It is also possible to do so. 7 is an electrode pattern for taking a return from a common electrode, which will be explained later. Note that the thickness of these conductor layers is generally 3 to 3.
It is about 5 μm.

FIG. 4 shows a step of forming a glass layer 8, which will serve as an electrical insulating layer and a thermal resistance layer, on the individual electrode layer 3. As shown in the figure, high melting point glass or the like is printed on the individual electrode layer 3 and fired. The film thickness after firing is selected to be 50 to 100 μm as necessary. In general, the thickness of the thick glass layer after firing is 20 to 30 μm.
However, by repeating the same steps, the required film thickness can be obtained and the film thickness can be controlled.

FIG. 5 shows a step of forming the second electrode layer 4 on the glass layer 8. In this case, the electrode layer 4 (hereinafter referred to as
After passing over the glass layer 8, the common electrode layer 4) is connected to the electrode pattern 7 described above.

FIG. 6 shows a step of printing and firing a glass layer 9 on the surface of the substrate 1 except for the lead extraction portions in order to protect the individual electrode layers 3 and the common electrode layer 4.
The material of this protective glass layer 9 is the same high melting point glass as the glass layer 8 described above. This protective glass layer 9 is attached to the electrode layer 3 when cutting the edge of the substrate as described below.
This is to prevent the peeling etc. of 4. In addition, this glass layer is made of aluminum oxide (Al ₂ O ₃ ), for example, in consideration of wear resistance and thermal conductivity.
It is also effective to add powder of

In FIG. 7, the end of the board 1 is cut, and the heating resistor 2 is cut off.
This is the process of forming the end surface to which the material is to be applied. The substrate 1, which has been successively laminated and wired as shown in FIGS. 2 to 6, is cut at the position of straight line a in the figure. 8th
The figure shows the state of the end face. As shown in the figure, individual electrode layers 3 (individual electrodes 31 to 3
8) and the common electrode layer 4 are now exposed,
Moreover, these electrodes face each other with the glass layer 8 in between. Note that if the surface roughness of the end face after cutting is lower than a predetermined standard, polishing is performed to give the surface a mirror finish.

A resistive material such as tantalum nitride (Ta ₂ N) or nichrome (Ni-Cr) is deposited on the end face thus formed by sputtering or vapor deposition to form the heating resistor 2 . The film thickness of the heating resistor 2 in this case is determined in relation to its resistance value, and is approximately 0.1 μm.

By the above process, the heating resistor 2 is uniformly formed on the exposed end surfaces of the individual electrodes 31 to 38 and the common electrode layer 4, and is electrically connected to these electrodes. Each individual electrode 31-38
It is necessary to separate each.

FIG. 9 shows a state in which the heating resistor 2 is separated into shapes corresponding to the individual electrodes 31-38.
In the illustrated example, the heating resistor 2 is separated using a laser cut, and 10 is the locus of the laser cut. In addition, in the figure, the heating resistor 2 is formed on the entire end surface of the substrate 1, so
Illustration is omitted here. The width of the laser cut (the line width of the locus 10) is determined by the spot diameter of the laser beam, and the minimum width can be up to about 20 μm, making it easy to form a heating resistor with high density.

Further, as shown in the figure, the length of the heating resistor 2 is determined by the thickness of the glass layer 8 interposed between the individual electrodes 31 to 38 and the common electrode layer 4; By adjusting the length of the heating resistor 2, the length of the heating resistor 2 can be arbitrarily controlled.

When the heating resistor 2 is separated in this way,
An insulating layer of silicon oxide (SiO ₂ ), tantalum pentoxide (Ta ₂ O ₅ ), boron nitride (BN), silicon carbide (SiC), etc. is deposited as a protective and wear-resistant layer for the heating resistor 2 by sputtering or vapor deposition. be done. Furthermore, in consideration of thermal conductivity, a wear-resistant metal layer may be applied by dispersion plating after insulating with silicon oxide or the like. In this case, nickel is mainly used for the metal film, and by adding aluminum oxide, boron nitride, diamond, etc. as a dispersant, thermal conductivity and wear resistance can be improved.

The above is the basic manufacturing process for a vertical thermal head.In the thermal head of the present invention, a preheating heater is formed at the same time as the heating resistor on the end face of the substrate formed as described above. This is how it was done.

FIG. 1 is a block diagram showing an embodiment of the thermal head of the present invention. In the figure, reference numeral 5 denotes a preheating heater formed by laser cutting a heating resistor uniformly adhered to the end surface of the substrate 1 into the pattern shown in the figure. The heater electrode 6 connected to the preheating heater 5 is patterned at the same time as the individual electrode layer 3 in the individual electrode layer forming process shown in FIGS. 2 and 3.

In this way, by cutting the ends of the substrate 1 and forming the heating resistor 2 and the preheating heater 5 on the exposed end surfaces of the electrode layers 3, 4, and 6, a vertical thermal head is formed. In a series of manufacturing processes, the preheating heater 5 can be formed without requiring many man-hours, and
At the end face where the heating resistor 2 and the preheating heater 5 are formed, the exposed area of the electrodes 3 and 4 connected to the heating resistor 2 is small, so the preheating heater 5 is placed near the heating resistor 2. can be placed. Therefore, the heat transfer time between the preheating heater 5 and the heat generating resistor 2 is shortened, and if the preheating heater 5 is driven in synchronization with the printing pulse of the heat generating resistor 2, the heat generating resistor 2 Due to the thermal bias effect, the pulse width of the printing pulse can be narrowed, and the printing speed can be increased.
Further, at this time, the range of temperature change in the heat generating resistor 2 becomes smaller, so that the life of the heat generating resistor 2 can be extended. Furthermore, since the temperature of the substrate 1 can be quickly controlled, the temperature of the substrate 1 can be quickly controlled.
It is possible to maintain a constant temperature at all times, and it is possible to prevent print quality from deteriorating during startup.

In the above explanation, laser cutting was exemplified as a means for separating the heat generating resistor formed on the end surface of the substrate 1, but there are other means for separating the heat generating resistor such as etching by photolithography and blade cutting. There are mechanical cutting methods, sandblasting methods, etc., which can be used depending on the need. In addition, the wear-resistant layer formed on the heating resistor 2 and the preheating heater 5 is
It is not limited to an insulating thin film, and a glass layer can also be used. Then, attach an aluminum plate or ceramic plate on the electrode protective glass layer.
It is also possible to correct warpage of the substrate while maintaining mechanical strength.

FIGS. 10 to 13 are block diagrams showing other embodiments of the thermal head of the present invention. The thermal head shown in FIG. 10 is a multi-stylus heating resistor 2 used in a line printer, for example, and a large number of heating resistors 2 are formed as an example.

The thermal head shown in FIG. 11 is designed to remove excess resistive material deposited on the end surface of the substrate 1. This resistive material is removed, for example, by scanning with a laser.

The thermal head shown in FIG. 12 is one in which the shape of the preheating heater 5 is changed, and here,
In order to realize a preheating heater 5 having a desired resistance value from a resistive material with a constant sheet resistance, the pattern is meandered.

In the thermal head shown in FIG. 13, the preheating heater 5 is divided into two parts, each of which can be driven independently, allowing precise control of the substrate temperature, etc.

〔Effect of the invention〕

As explained above, in the thermal head of the present invention, a plurality of electrode layers are successively stacked on one surface of the substrate so as to face each other with an electrical insulating layer and a glass layer serving as a thermal resistance layer interposed therebetween. Each layer included in the electrode layer is cut in a straight line, and the heating resistor and preheating heater are formed on the exposed end face of each electrode layer, so the preheating heater can be placed near the heating resistor. By shortening the heat transfer time between the preheating heater and the heating resistor, the printing speed can be increased due to the thermal bias effect of the heating resistor, and the temperature of the board can be quickly controlled, making it easy to use at startup. A thermal head that can prevent print quality from deteriorating can be realized with a simple configuration.

[Brief explanation of the drawing]

1 to 13 are block diagrams showing embodiments of the thermal head of the present invention, and FIG. 14 is a block diagram showing an example of a conventional thermal head. 1...Substrate, 2...Heating resistor, 3, 31-3
8...Individual electrode (layer), 4...Common electrode (layer), 5
... Heater for preheating, 6 ... Electrode for heater, 7
... Electrode pattern, 8 ... Glass layer, 9 ... Protective glass layer, 10 ... Laser cut.

Claims (1)

[Claims] 1 a substrate, an individual electrode layer laminated on the surface of this substrate and consisting of an individual electrode for selectively driving a heat generating resistor and an electrode for driving a preheating heater; a glass layer that is laminated to serve as an electrical insulating layer and a thermal resistance layer;
A common electrode layer is laminated on the glass layer, and a resistance material is attached to the end surface where the individual electrode layer and the common electrode layer are exposed by cutting or polishing the end portion of the substrate including each of the layers. , a thermal head characterized in that the resistive material is separated and the part deposited on the glass layer is used as a heating resistor, and the part deposited on the substrate is used as a heater for preheating. .