JP3038263B2 - Thick film type thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thick film type thermal head used for a thermal recording means such as a facsimile or a line thermal printer.

[0002]

2. Description of the Related Art FIG. 5 shows a common conductor pattern in a conventional thermal head. Conventionally, heating resistor arrays 2 are arranged in a row on an insulating substrate 1, and one conductor pattern of each heating resistor is connected to one as a common conductor 3. Further, a protective film 4 is formed on the upper surface of the heating resistor array 2 and a part of the common conductor 3 so as to cover a part thereof.

[0003] The conductor width of the common conductor 3 is preferably as wide as possible in order to reduce the print density variation in the direction of the row of heating resistors.
Thereby, the conductor resistance of the common conductor 3 can be reduced, and variation in the amount of voltage drop can be reduced.

[0004]

In contrast, in recent years,
There is a high demand for miniaturization of the thermal head, and
The smaller the width of the conductor, the smaller the size of the conductor. However, the conventional thermal head has the following problems.

Usually, the common conductor 3 is formed simultaneously with other conductor circuits by photolithography. However, in this method, there is a limit in reducing the conductor width. If the conductor width is simply reduced, the conductor resistance increases. The print density varies.
In order to avoid this, there is a method of forming a new conductor on the common conductor 3 to reduce the conductor resistance. In this case, however, the protection is performed so as to overlap with a part of the common conductor 3 whose thickness is increased. Since the film 4 is formed, the surface of the protective film in the vicinity of the heating resistor array that comes into contact with the platen 5 becomes convex, and unevenness of the convex portion causes printing unevenness and paper feed failure due to accumulation of printing chips generated from the thermal paper. Will occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to solve the above-mentioned conventional problems and to provide a small-sized thick-film type thermal head having low common conductor resistance. Is what you do.

[0007]

According to a first aspect of the present invention, there is provided a thick-film type thermal head including a heating resistor array protected by a protective film on an insulating substrate and a common conductor of the heating resistor array. In the thermal head, the common conductor is so formed as to be substantially equal to the thickness of the protective film and formed outside the protective film.

According to a second aspect of the present invention, there is provided a thick film type thermal head.
2. The thick film type thermal head according to claim 1, wherein a part of the common conductor located at a position distant from the heating resistor row is formed on the protective film.

[0009]

According to the first aspect of the present invention, since the common conductor is formed thick, a sufficient conductor cross-sectional area can be secured even if the width is reduced, and a uniform print density can be secured over the entire length of the heating resistor array. The size of the thermal head can be reduced.

According to the second aspect of the present invention, a portion of the common conductor is formed on the protective film at a position distant from the heating resistor row where no problem occurs in relation to the thermal paper or the like, thereby further reducing the size. Plan.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to various embodiments shown in FIGS.

Embodiment 1 FIG. 1 is an embodiment 1 showing a thick film type thermal head of the present invention. The heating resistor rows 12 are arranged in a line on the insulating substrate 11, and the heating resistor rows 12 are covered with a protective film 13.

Further, after forming the protective film 13, using a device such as a dispenser, the common conductor 14 in which one conductor pattern of each heating resistor is integrated into one is substantially equal in thickness to the protective film 13. It is formed as thick (high) as possible and outside the protective film 13. That is, the common conductor 14 is formed to be narrower than the conventional one so as to be in contact with the peripheral surface of the protective film 13 outside the area where the protective film 13 is formed.

As described above, since the common conductor 14 is formed to be thick, a sufficient conductor cross-sectional area can be ensured even when the conductor width is reduced and the size is reduced, so that the conductor resistance can be kept low. A uniform printing density can be obtained from the entire length of the heating resistor array 12.

Table 1 below shows a comparison of the conductor resistance values of the common conductor.

[0016]

[Table 1] Embodiment 2 FIG. 2 shows Embodiment 2 showing a thick-film type thermal head having the same basic configuration as Embodiment 1 (FIG. 1). In order to draw the end to the same side, a part of the common conductor 14a is routed so as to be in contact with the peripheral surface of the protective film 13. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

Third Embodiment FIG. 3 shows a third embodiment in which a portion of the common conductor 14 b located at a position away from the heating resistor array 12 is formed on the protective film 13. On the protective film 13 at a position distant from the heating resistor row 12, a sufficient thermal paper insertion space can be secured between the common conductor 14b and the platen 15, so that the thermal paper 16 No contact is made, and the size of the common conductor 14b is formed on the protective film 13, so that the size of the thermal head can be further reduced. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

Embodiment 4 FIG. 4 shows that the thickness of the protective film 13 is substantially equal to that of the protective film 13.
Further, after forming the common conductor 14 narrowly so as to be in contact with the peripheral surface of the protective film 13 outside the formation range of the protective film 13, the common conductor 14 is formed on the protective film 13 and the common conductor 14 as shown in FIG.
As shown in (D), the auxiliary protective film 13 is formed on the common conductor 14.
Example 4 in which a was formed. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0019]

According to the first aspect of the present invention, since the thickness of the common conductor is formed to be substantially equal to the thickness of the protective film, the conductor resistance increases even if the width of the common conductor is reduced. While reducing the size of the common conductor,
Variations in print density can be prevented. Also, since the common conductor is formed outside the protective film, a new conductor is formed on the common conductor as in the related art, so that the surface of the protective film in the vicinity of the heating element does not become convex, and printing is performed. There is also an effect that the occurrence of a paper feed failure or the like due to unevenness or accumulation of print residue can be prevented.

According to the second aspect of the present invention, the thick-film type thermal head is further reduced in size by forming a portion of the common conductor on the protective film within a range that does not cause a problem in relation to the thermal paper or the like. it can.

[Brief description of the drawings]

FIG. 1A is a plan view showing a first embodiment of a thick film type thermal head according to the present invention, and FIG. 1B is a side view thereof.

FIG. 2A is a plan view showing a thick-film type thermal head according to a second embodiment of the present invention, and FIG. 2B is a side view thereof.

FIG. 3A is a plan view showing a third embodiment of the thick film type thermal head of the present invention, and FIG. 3B is a side view thereof.

4A is a plan view showing a thick-film type thermal head according to a fourth embodiment of the present invention, FIG. 4B is a side view thereof, and FIG. 4C is a cross-sectional view showing an example of forming an auxiliary protective film; (D) is a sectional view showing another example of forming the auxiliary protective film.

FIG. 5A is a plan view showing a conventional thermal head,
(B) is a side view thereof.

[Explanation of symbols]

 11 Insulating substrate 12 Heating resistor array 13 Protective film 14 Common conductor

Continued on the front page (72) Inventor Yoshihisa Obata 1-19-43 Higashi-Oizumi, Nerima-ku, Tokyo Inside Tamura Manufacturing Co., Ltd. (56) References JP-A-63-264370 (JP, A) JP-A-60- 63175 (JP, A) JP-A-60-116474 (JP, A) JP-A-4-307262 (JP, A) JP-A-1-158136 (JP, U) JP-A-3-45139 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41J 2/335

Claims (2)

(57) [Claims] 1. A thermal head in which a heating resistor array protected by a protective film on an insulating substrate and a common conductor of the heating resistor array are provided, wherein the common conductor has a thickness substantially equal to the thickness of the protective film. A thick-film type thermal head characterized in that it is thick enough to be equivalent and formed outside the protective film. 2. The thick film type thermal head according to claim 1, wherein a part of the common conductor located at a position distant from the heating resistor row is formed on the protective film.