JPS61162369A - Thermal head - Google Patents

Abstract

PURPOSE:To improve temperature distribution in a heating element and enhance characteristics of a thermal head, by providing a heating resistor with one or a plurality of windows the length of which is 1/N times of the overall length of the resistor. CONSTITUTION:The heating resistor 3 is provided with one or more window 5 by etching, sputtering or the like. When a thermal head is constructed by using the heating resistors 3 with the shape as shown in Fig. 3, the heating values in the vicinity of a driving circuit side electrode 1 and in the vicinity of a common electrode 4 can be set to be considerably lower than that at a central part of the resistor 3. Therefore, as indicated by a temperature distribution TA in Fig. 2, the temperature rises i the vicinity of the electrode 1 and in the vicinity of the electrode 4 can be considerably suppressed, as compared with that at a central part of the resistor 3. Further, as indicated by a temperature distribution TB in Fig. 3 it is possible to generate heat only at the central part of the resistor 3 without generating heat in the vicinity of the electrode 1 or in the vicinity of the electrode 4, by varying electric power impressed on the resister 3, and accordingly, gradation recording can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal head used in printers, fax machines, etc.

[Prior art]

FIG. 4 is a configuration diagram of a conventional thermal head. In the figure, (1) is the drive circuit side electrode, (2) is the insulating substrate, and (3)
is a heating resistor, and (4) is a common electrode. FIG. 5 is a sectional view showing the temperature distribution TA of the thermal head on line A-A in FIG. In Fig. 5, (a) shows an isothermal line near the heating resistor (3) in Fig. 4 when the power applied to the heating resistor (3) in Fig. 4 is small, and (b) shows the isothermal line in the vicinity of the heating resistor (3) in Fig. 4. FIG. 4 shows isothermal lines near the heating resistor (3) when a large amount of power is applied to the heating resistor (3). Here, the isothermal line (a) and the isothermal line (b) in FIG. 5 are at the same temperature, indicating the temperature required to obtain a record using the thermal head.

Figure 6 shows the surface temperature distribution TB of the heating resistor (3) in Figure 4.
shows.

[Problem that the invention seeks to solve]

When a thermal head is constructed using a heating resistor shaped as shown in FIG. 4, heating resistor (3), heat is also generated near both electrodes of the heating resistor (3) in FIG. For this reason, the fifth
As shown in the temperature distribution TA in the figure and the temperature distribution TB in FIG. 6, the temperature also increases near the drive circuit side electrode (1) in FIG. 4 and the common electrode (4). However, the vicinity of the electrode is often a part that does not come into contact with an opposing object such as a platen, and thus heat cannot be transferred to the opposing object. For this reason, there was a problem that the power durability deteriorated. Also, the temperature distribution T
As shown in Fig. 4, when the power applied to the heating resistor (3) in Fig. 4 is changed, only the center of the heating resistor (3) in Fig. 4 cannot be heated, and the drive circuit in Fig. 4 Side electrode (1)
Because it generates a lot of heat in the vicinity and near the common electrode (4),
There was a problem with not being able to record gradations.

In addition, in a thermal transfer recording device using a thermal head as shown in Figure 4, when recording an image using a plurality of rectangular dots with short sides in the sub-scanning direction, the heating resistor (3) shown in Figure 4 It was necessary to use a special thermal head with a shorter overall length. However, when this type of thermal head is used, there is a problem in that the contact rate with an opposing object such as a platen deteriorates.

[Means to solve problems]

In order to solve this problem, the present invention is such that the heat generating resistor has one or more windows having a length of 1:N (N(0,6)) compared to the total length of the heat generating resistor. be.

[Effect]

The thermal head according to the present invention improves the temperature distribution of the heating resistor and improves the characteristics of the thermal head by providing the above-mentioned predetermined windows in the heating resistor.

[Embodiments of the invention]

Examples of the present invention will be described below.

FIG. 1 shows a thermal head according to an embodiment of the invention. In the figure (11 is the drive circuit side electrode, (2) is the insulating substrate, (3) is the heating resistor, (4) is the common electrode, (5) is formed on the heating resistor (3) by etching or sputtering, etc. It is a window.

FIG. 2 is a cross-sectional view showing the temperature distribution TA of the thermal head along line A-A in FIG. In Figure 2, (a)
Figure 1 shows the equal crosstalk near the heating resistor (3) in Figure 1 when the power applied to the heating resistor (3) is small, and (b)
shows equal crosstalk near the heating resistor (3) in FIG. 1 when a large amount of power is applied to the heating resistor (3) in FIG. here,
The equimixture line (a) and equimixture line (b) in FIG. 2 have the same zero temperature, indicating the temperature required for recording using a thermal head.

Figure 8 shows the surface temperature distribution TB of the heating resistor (3) in Figure 1.
shows.

When configuring a thermal head using a heating resistor shaped like the one shown in Figure 1 heating resistor (3), the amount of heat generated near the center of the heating resistor (3) in Figure 1 is compared with that shown in Figure 1. The amount of heat generated near the circuit side electrode (1) and the common electrode (4) can be considerably reduced, which reduces the temperature rise near the center of the heating resistor (3) in Figure 1, as shown in temperature distribution TA in Figure 2. When compared with the method shown in FIG. 1, the temperature rise near the drive circuit side electrode (1) and the common electrode (4) in FIG. 1 can be considerably suppressed. This has the effect of improving the deterioration in power durability, which has been a problem in the past. Further, recording can be performed without using the areas near both electrodes, which conventionally had a poor contact rate with an opposing object such as a platen, and the quality of recorded images can be improved.

Furthermore, as shown in the temperature distribution TB in FIG. 8, by changing the power applied to the heating resistor (3) in FIG.
It is also possible to generate heat only near the center of the heating resistor (3) in Figure 1, near the drive circuit side electrode (1) or the common electrode (4).
) can be done so that almost no heat is generated in the vicinity, which has the effect of allowing gradation recording.

Further, a thermal transfer recording device using a thermal head as shown in FIG. 1 can improve the contact rate with an opposing object such as a platen.

Furthermore, rectangular dots with short sides in the sub-scanning direction can be easily realized by simply etching or sputtering the heating resistor of a conventional thermal head. As a result, even if the thermal head has a low resolution in the main scanning direction, by setting the short side length of the dot appropriately, the resolution in the main scanning direction can be improved compared to the resolution in the main scanning direction of the thermal head actually used in the thermal transfer recording device. It has the effect of being able to obtain recorded images equivalent to those using a high-performance thermal head.

Although the case where the heat generating resistor has two windows has been described above, the present invention is not limited to this, and the heat generating resistor may have a single window or a plurality of windows of any shape.

[Effect of the invention 1 As described above, according to the thermal head according to the present invention, by providing a predetermined window in the heating resistor, the amount of heat generated in any part of the heating resistor can be controlled. In addition to increasing the power resistance of the head and achieving gradation recording, by appropriately setting the length of the dots in the sub-scanning direction of the thermal head, it is possible to achieve higher resolution than the thermal head actually used. A recorded image equivalent to that obtained using a thermal head can be obtained and is effective.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a thermal head according to an embodiment of the present invention, FIG. 2 is a sectional view showing the temperature distribution TA of the thermal head on line A-A in FIG. 1, and FIG. FIG. 4 is a diagram showing the surface temperature distribution TB of the heating resistor (3) in the figure.
The configuration diagram of a conventional thermal head, Fig. 6, is shown in A in Fig. 4.
FIG. 6 is a sectional view showing the temperature distribution TA of the thermal head on the line -A, and is a diagram showing the surface temperature distribution TB of the heating resistor (3) in FIG. In the figure, (1) is the drive circuit side electrode, (2) is the insulating substrate,
(3) is a heating resistor, (4) is a common electrode, (5) is a window formed on the heating resistor (3) by etching, etc.;
(a) is an isothermal line when the electric power applied to the heating resistor (3) is small, and (b) is an isothermal line when the electric power applied to the heating resistor (3) is large. In the drawings, the same or equivalent parts are designated by the same reference numerals.

Claims (2)

[Claims] (1) In a thermal head having an insulating substrate, a plurality of heating resistors arranged and formed on the substrate, and each pair of electrodes formed on the substrate in contact with the heating resistors, respectively. . A thermal head, wherein the heating resistor has one or more windows having a length of 1:N (N<0.6) compared to the total length of the heating resistor. (2) The thermal head according to claim 1, wherein the heating resistor of the thermal head is formed of a plurality of rectangular dots having short sides in the recording sub-scanning direction.