JPH04344262A - Thermal head - Google Patents

Abstract

PURPOSE:To provide a thermal head which is free from deterioration in printing quality even in printing at high speed and achieve durability. CONSTITUTION:In a thermal head wherein a head proper 7 which records on the opposed recording paper by applying specific heat to a perforated film containing ink is provided, and this head proper 7 is equipped with a substrate 7 supporting a plurality of heating elements, a heating resistor 3 as the heating element equipped to this substrate via a glazed layer 2, and an electrode 4 which makes a current for heating flow to this heating resistor 3, the substrate 3 is formed by a material of excellent thermal conductivity.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head, and more particularly to a thermal head suitable for a thermal inkjet printer.

0002

2. Description of the Related Art In recent years, various types of printers have been proposed and put into practical use. And ink in it,
There is an inkjet printer in which ink is ejected from a fixed nozzle to record on a recording medium. This inkjet printer operates with low power consumption and low noise, and is compact and
It has advantages such as easy colorization.

[0003] However, this inkjet printer has low reliability because the problem of nozzle clogging has not been completely solved. Furthermore, as a system for solving such problems, there is an invention described in Japanese Patent Laid-Open No. 60-71260. This invention discloses a thermal inkjet printer, a part of which is shown in FIG. This thermal inkjet printer includes a thermal head 23 and a perforated film 21 that runs in contact with the thermal head 23. Furthermore, the above thermal head is formed of a plurality of heating elements (not shown) and a substrate 25 that supports the heating elements. Further, the perforated film 21 has a plurality of through holes 22, and ink is held in the through holes 22. Then, heat is generated by selectively energizing the plurality of heating elements in the thermal head described above, and the generated heat is applied to the ink in the through holes 22 in the perforated film 21 to heat and boil the ink. It is something that makes you fly. This flying ink is then transferred to the recording paper 24 as a mosaic of dots.

The advantage of this method is that a fixed nozzle is not used, and the ink in the through holes 21 formed in the perforated film 21 are successively heated and boiled as nozzles, so that clogging and the like occur. It's hard to do. In addition, such thermal inkjet printers using a perforated film are of a cylindrical type as described in Japanese Patent Application Laid-Open No. 1-139278, so that the perforated film can stably run in contact with the thermal head. Thermal heads are often used.

[0005]

[Problems to be Solved by the Invention] However, in the above-mentioned cylindrical thermal head 23, since the substrate 25 that supports the heating element is made of glass with low thermal conductivity, a current suddenly flows through the heating element. The temperature of this heating element rises rapidly in a short period of time. On the other hand, since the heating element is cooled mainly by heat radiation through natural heat conduction from the heating element to surrounding members, it takes time for the temperature to drop. For these reasons, there is no problem if the thermal response of the thermal head can follow the cycle of the print signal, but it is necessary to make the thermal head perform high-speed printing by frequently supplying or stopping current to the heating element. As the cycle of the print signal becomes shorter, the thermal response of the thermal head becomes unable to follow it. For this reason, the thermal head accumulates heat, and this accumulated heat heats and boils the unnecessary ink (ink that is originally not desired to be transferred onto the recording paper) in the perforated film described above and causes it to fly onto the recording paper. As a result, printing quality deteriorates, and furthermore, the thermal head itself may be destroyed due to thermal stress.

[0006]

[Object] The purpose of the present invention is to improve the disadvantages of the conventional example, and in particular, to provide a thermal head that does not deteriorate in print quality even in high-speed printing and has increased durability. do.

[0007]

[Means for Solving the Problems] The present invention has a head body that performs recording on opposing recording paper by applying a predetermined amount of heat to a perforated film holding ink. A thermal head comprising a substrate supporting a heating element, a heating element attached to the substrate via a glaze layer, and an electrode for passing a current for heating to the heating element, and the above-mentioned substrate. is made of a material with good thermal conductivity. Further, this substrate is formed of aluminum nitride, and furthermore, the above-mentioned glaze layer is formed of a relatively thin glass film. This is intended to achieve the objectives mentioned above.

[0008]

[Operation] When current flows from the electrodes of the head body to the plurality of heating elements, the heating elements generate heat. Furthermore, this heat generation increases rapidly in a short period of time due to the heat retention properties of the glaze layer. This rapidly increased heat is then applied to the ink held in the through holes of the perforated film. Then, this ink heats up and boils, causing it to fly. This flying ink is recorded on the recording paper as a mosaic of dots. Moreover, when the current from the electrodes stops, the heat accumulated in the heat generating element is relatively quickly absorbed by the substrate supporting the heat generating element via the glaze layer. Therefore, the head body is quickly cooled down and no extra heat is applied to the ink in the perforated film. Therefore, unnecessary ink is not transferred to the recording paper.

[0009]

[Embodiment] An embodiment of the present invention will be described below based on FIG. Here, the description of the same components as those of the conventional example described above will be simplified or omitted.

FIG. 1 shows a partially omitted sectional view of a thermal head 8 in this embodiment. In this diagram,
Reference numeral 7 designates a head main body that applies a predetermined amount of heat to a perforated film holding ink to perform recording on the opposing recording paper. The head body 7 includes a substrate 1 supporting heating elements, heating resistors 3 as a plurality of heating elements attached to the substrate 1 via a glaze layer 2, and a heating resistor 3 for heating. The electrode 4 is provided with an electrode 4 through which a current flows. The substrate 1 described above is made of a material with good thermal conductivity (for example, aluminum nitride, etc.). Also,
The glaze layer 2 described above is formed of a relatively thin glass film.

To explain this in more detail, the substrate 1 is made of aluminum nitride and has a cylindrical cross-section and a diameter of 2 mm. A glass glaze layer 2 having a thickness of 1 μm is formed on the entire surface of the substrate 1. Furthermore, the upper surface of this glaze layer 2 (upper side in FIG. 1)
A nichrome antipyretic antibody 3 with a thickness of 0.1 [μm] is attached to a part of the body. Further, a copper electrode 4 having a thickness of 1 [μm] is formed on the low heat generation antibody 3. here,
The above-mentioned electrode 4 is not formed in the heat-generating portion 5 as the heat-generating portion of the hypothermic antibody 3 . Furthermore, a layer with a thickness of 5 [
A protective layer 6 of silicon nitride with a thickness of [μm] is formed. The upper part (upper side in FIG. 1) of this protective layer 6 is formed into a circular shape because it is the contact surface with the above-mentioned perforated film.

Next, the printing operation of this thermal head 8 will be explained.

When a current flows from the electrode 4 provided on the head body 7 to the plurality of heat-generating low antibodies 3, the heat-generating portion 5 of the heat-generating resistor 3 generates heat. Furthermore, this heat generation increases rapidly in a short period of time due to the heat retention properties of the glaze layer 2. This rapidly increased heat is then applied to the ink held in the through holes of the perforated film. Then, this ink heats up and boils, causing it to fly. This flying ink is recorded on the recording paper as a mosaic of dots. Further, when the current from the electrode 4 is stopped, the heat accumulated in the heat generating portion 5 of the heat generating hypoantibody 3 is absorbed relatively quickly by the substrate 1 supporting the heat generating hypobody 3 via the glaze layer 2. Therefore, the head body 7 is quickly cooled down and no extra heat is applied to the ink in the perforated film. Therefore, unnecessary ink is not transferred to the recording paper.

Furthermore, in this embodiment, aluminum nitride, which has a high thermal conductivity (approximately 100 to 200 times that of glass), is used as the substrate 1 that supports the heat-generating low antibody 3. Furthermore,
A relatively thin glass glaze layer 2 is interposed between the heating resistor 3 and the substrate 1 described above. Therefore, the cooling time of the heating element after heating is shortened, resulting in high-speed response and no deterioration in print quality even in high-speed printing. Also,
Since thermal stress caused by heat accumulation can be effectively prevented, a thermal head with increased durability can be provided. Here, although the substrate 1 described above is formed in a cylindrical shape, the same effect can be obtained even if it is formed in a circular shape. Furthermore, the thermal head 8 of this embodiment can also be applied to a thermal printer or the like.

[0015]

Effects of the Invention Since the present invention is constructed and functions as described above, the heating element is attached to a substrate with good thermal conductivity through a relatively thin glaze layer, so that the thermal responsiveness is improved. becomes faster. In addition, thermal stress caused by heat accumulation can be effectively prevented. Therefore, it is possible to provide an unprecedented thermal head that does not deteriorate in print quality even in high-speed printing and has increased durability.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the present embodiment.

FIG. 2 is a diagram illustrating a conventional example.

[Explanation of symbols]

1 Board 2 Glaze layer 3. Heat-generating hypoantibody as a heat-generating element 4 Electrode 7 Head body 8 Thermal head

Claims (3)

[Claims] 1. A head main body that performs recording on an opposing recording paper by applying a predetermined amount of heat to a perforated film holding ink, and the head main body includes a substrate supporting a plurality of heat generating elements; In a thermal head comprising a heating element attached to the substrate via a glaze layer and an electrode for passing a current for heating to the heating element, the substrate is formed of a material with good thermal conductivity. A thermal head characterized by 2. The thermal head according to claim 1, wherein the substrate is made of aluminum nitride. 3. The thermal head according to claim 1, wherein the glaze layer is formed of a relatively thin glass film.