JPH06206330A - Thermal head - Google Patents

Abstract

PURPOSE:To prevent a hickey from occurring in a printed result and make a zigzag feeling occurring in an oblique line inconspicuous. CONSTITUTION:A common electrode connection part 2b and a discrete electrode top part 3a intersect both side edges 4R, 4L of a band-form heating resistor 4 in a sub-scanning direction at positions shifted to each other in a main scanning direction X. The outer shape of a heating element 4a of a thermal head is substantially rectangular. In this case, a zigzag feeling is unavoidably generated in a line obliquely drawn. A line printed slantly to the right and a line printed slantly to the left have the same zigzag feeling, thus never producing a sense of incompatibility. In addition, the heating part is not divided into simple parts, but in two of those, one is projected into the other. In this case, when a plurality of lines are continuously printed, the surface of printing paper is fed in contact with the surface of the heating part. Thus, a hickey is not generated. In this manner, a straight line caused by a hickey is not generated in a printed result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head used in a recording section of a facsimile machine, a printer or the like,
In particular, the present invention relates to a thermal head in which a plurality of common electrodes and individual electrodes that are alternately arranged are connected by a strip heating resistor.

[0002]

2. Description of the Related Art FIGS. 5A and 5B show an example of a conventional thermal head using a strip-shaped heating resistor. FIG. 5A is a plan view of a main portion and FIG. 5B is a sectional view taken along line VB-VB of FIG. 5A. . In FIG. 5, the insulating substrate 01 is composed of a ceramic substrate 01a and an underglaze layer 01b formed on the entire surface thereof. A common electrode 02 and a plurality of individual electrodes 03 extending in the sub-scanning direction Y are formed on the upper surface of the insulating substrate 01. The common electrode 02 includes a strip-shaped common electrode body portion 02a extending along the main scanning direction X, and a plurality of common electrode connecting portions 0 extending in the sub-scanning direction Y in a comb shape from the body portion 02a.
2b and. Each of the plurality of individual electrodes 03 has a large number of individual electrode tips 03a alternately arranged with the common electrode connecting portion 02b.

On the insulating substrate 01 on which the common electrode 02 and the individual electrode 03 are formed, a strip-shaped heating resistor 04 extending along the main scanning direction X is formed. The strip-shaped heating resistor 04 is divided into a plurality of heating elements 04a by a plurality of common electrode connecting portions 02b extending in the sub scanning direction Y. Each heating element 04a generates heat when energized between a pair of common electrode connecting portions 02b adjacent to each other and one individual electrode tip portion 03a arranged between them, and prints one printing dot. You can do it. The surface of the insulating substrate 1 on which the electrodes 02 and 03 and the plurality of heat generating resistive elements 04a are formed is a wear resistant layer 05 made of glaze.
It is covered with. Then, one printed portion 05a is formed by the wear-resistant layer 05 covering the surface of one heating element 04a.
Are formed.

In the heating element 04a, the heating resistor portion which overlaps the common electrode connecting portion 02b and the individual electrode tip portion 03a does not generate heat. This non-heat generating portion is likely to cause so-called white spots during printing. FIG. 6 shows the color development result when the conventional thermal head shown in FIG. 5 is used. In FIG. 6, a white void W1 having a width corresponding to the width of one common electrode connecting portion 02b is generated between two adjacent dots. In addition, a white spot W2 having a width corresponding to the width of one individual electrode tip portion 03a is generated corresponding to the individual electrode tip portion 03a in the area of one dot. Due to this blank W2, one dot is divided into two in the main scanning direction X. When the printing dots as shown in FIG. 6 are continuously printed, a large number of straight white lines may be generated and a striped pattern may be noticeable.

As described above, the width of the white line portion is influenced by the widths of the common electrode connecting portion 02b and the individual electrode tip portion 03a. In order to improve the connection between the dots or within the dots and to make the white areas thin and inconspicuous, the individual electrode tip portions 03a and the common electrode connection portions 02b may be formed as thin as possible. However, there are limits to making the electrodes thin as follows. The common electrode connecting portion 02b and the individual electrode tip portion 03a are usually formed by photolithographically etching a conductor film formed of an electrode material uniformly in a predetermined region on the insulating substrate 03 with a predetermined film thickness. If the electrode thus formed is made as thin as possible, it may cause a short circuit or disconnection due to exposure, development, or etching in the photolithography etching process and lose its function as an electrode. There is.

As described above, if the connection between dots or within dots is poor, white spots occur during printing, and if white spots continue, white lines are conspicuous, which adversely affects print quality. Therefore, in order to prevent the occurrence of the above-mentioned white spots or thin print portions and improve the connection between the print dots to improve the print quality, the shape of the print dots, that is, the shape of the heating element, is made into a parallelogram with an inclination. Thing (JP-A-63-30
No. 2070) is proposed. In this way, when the shape of the print dots (shape of the heating element) is made an inclined parallelogram, the space between print dots (that is, the portion printed above the common electrode connection part) or the center of the print dots (that is, the tip of the individual electrode) White spots in the upper part of the printed area) are not noticeable.

[0007]

However, the above-mentioned Japanese Patent Laid-Open No.
When the shape of the heating element is tilted as proposed in Japanese Patent Laid-Open No. 3-302070, when a diagonal line along the tilted direction of the heating element and a diagonal line along the opposite direction to the tilted direction are printed. There was a problem that the jagged feeling (how to stand out) was different.

In view of the above circumstances, the present invention has an object of the following (O01) in a thermal head using a strip-shaped heating resistor. (O01) Prevent white spots when printed and make the jagged appearance of diagonal lines uniform.

The present invention devised to solve the above problems will now be described. The elements of the present invention are to facilitate correspondence with the elements of the embodiments described later. Note that the reference numerals of the elements of the embodiments are enclosed in parentheses. The reason why the present invention is described in association with the reference numerals of the embodiments described later is to facilitate the understanding of the present invention and not to limit the scope of the present invention to the embodiments.

In order to solve the above-mentioned problems, the thermal head of the present invention is a strip-shaped common electrode main body (2a) extending along the main scanning direction (X) and a sub-shaped comb-shaped sub-electrode from the main body (2a). A common electrode (4) having a large number of common electrode connecting portions (2b) protruding in the scanning direction (Y) and a large number of individual electrode tips (3a) alternately arranged with the common electrode connecting portions (2b) are provided. The individual electrode (3) having the strip-shaped heating resistor (4) extending along the main scanning direction (X) connecting the common electrode connection part (2b) and the individual electrode tip part (3a) is insulated substrate (1). ), Which is formed on the surface of (1) and connects one of the individual electrode tips (3a) and a pair of common electrode connecting portions (2b) arranged on both sides of the one individual electrode tip (3a). A heater in which a heating element (4a) for one print dot is formed by the heating resistor portion. In the thermal head,
It is characterized by having the following requirements (Y01) to (Y02). (Y01) The outer shape of the heating element (4a) is substantially rectangular, (Y02) Both side edges (4R, 4L) of the strip heating resistor (4) in the sub-scanning direction and the common electrode connecting portion (2b). ) And the individual electrode tip portion (3a) intersect each other in the main scanning direction (X).

[0010]

Next, the operation of the present invention having the above features will be described. The thermal head of the present invention having the above-mentioned characteristics,
The pair of common electrode connection portions (2b) of the strip-shaped heating resistor 4
The heat generating element (4a) formed by the portion between them is formed, and one heat generating element (4a) is separated into two heat generating portions by the individual electrode tip portion (3a). Both side edges (4R, 4L) of the strip heating resistor (4) in the sub-scanning direction (Y).
Since the position at which the common electrode connecting portion (2b) and the individual electrode tip portion (3a) intersect is displaced in the main scanning direction (X),
Adjacent ones of the heat generating portions are divided so as to enter each other in the main scanning direction (X). In this case, if only one line is printed, the heating resistor (4) on the common electrode connection part (2b) and the individual electrode tip part (2a) does not generate heat, so white spots may occur between the colored regions. . However, each colored area is not divided into two simple portions, but the divided two portions are divided so that they enter each other. Therefore, when a plurality of lines are continuously printed, the printing paper is Since the surface moves in contact with the surface of the heat generating portion, there is no white spot. Therefore, when printed, a straight line portion due to white spots does not occur.

Further, since one dot printed by one heating element (4a) is substantially rectangular, a zigzag feeling is inevitably generated when a line is drawn diagonally, but a printing line rising to the right and a printing line rising to the left. The zigzag feeling given to the line is the same, so there is no discomfort. That is, if the one-dot shape is, for example, an inclined parallelogram, there is no discomfort caused by the upward-sloping printed line and the upward-sloping printed line.

[0012]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. 1A and 1B show a first embodiment of a thermal head of the present invention, FIG. 1A is a plan view, and FIG. 1B is B of FIG.
It is a -B line sectional view. An underglaze layer 1b is formed on the entire surface of the ceramic substrate 1a. Insulating substrate 1 comprising the ceramic substrate 1a and the underglaze layer 1b
Is configured. The common electrode 2 is formed on the upper surface of the insulating substrate 1. The common electrode 2 is composed of a strip-shaped common electrode main body 2a extending in the main scanning direction X and a large number of common electrode connecting portions 2b protruding from the common electrode main body 2a in the sub-scanning direction Y in a comb shape. There is. Further, on the insulating substrate 1, individual electrodes 3 having a large number of individual electrode tips 3a alternately arranged with the common electrode connecting portions 2b are formed. A strip-shaped heating resistor 4 extending along the main scanning direction X is formed on the insulating substrate 1 on the upper surfaces of the common electrode connecting portion 2b and the individual electrode tip portion 3a. The surface of the insulating substrate 1 on which the electrodes 2 and 3 and the strip heating resistor 4 are formed is covered with a wear resistant layer 5 made of glaze.

The common electrode connecting portion 2b and the individual electrode tip portion 3a are orthogonal to the both side edges 4R, 4L at a position intersecting with the both side edges 4R, 4L of the strip-shaped heat generating resistor 4. Bent portions 2c and 3b that partially extend along the main scanning direction X are provided midway between the side edges 4R and 4L. That is, the positions where the both side edges 4R, 4L of the strip-shaped heating resistor 4 in the sub-scanning direction Y and the common electrode 2b and the individual electrode tip portion 3a intersect are displaced in the main scanning direction.

In the first embodiment having the above structure, the heating element 4a for one print dot (see FIG. 1A) is formed by the heating resistor portion between the pair of adjacent common electrode connecting portions 2b, 2b. In addition, both side edges 4R of the strip-shaped heating resistor 4,
Both 4L extend in the main scanning direction X and are parallel to each other. Therefore, the outer shape of the heating element 4a for one dot is substantially rectangular. A plurality of substantially rectangular heating elements 4a are provided in the main scanning direction X.
Are lined up.

When one line is printed by using the thermal head having a plurality of such heating elements 4a, the thermal paper develops color as shown in FIG. The portion between the heating elements 4a, 4a adjacent to each other in the main scanning direction X, that is, the common electrode connecting portion 2b
A bent white portion W1 is generated in the print area corresponding to. Further, a bent blank portion W2 also occurs in the central portion of each heating element 4a, that is, in the region corresponding to the individual electrode tip portion 2b.

When the blank areas W1 and W2 are bent in this way, when printing is continuously performed in the sub-scanning direction Y, colored portions (printed portions) continue in the sub-scanning direction Y. in this case,
A colored portion is also generated (printing is performed) in the white spots W1 and W2, and the white straight line does not occur.

(Embodiment 2) FIG. 3 is a plan view showing Embodiment 2 of the thermal head of the present invention. In FIG. 3 showing the second embodiment, the abrasion resistant layer is not shown. In the description of the second embodiment, constituent elements corresponding to those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. In FIG. 3, the shape of the common electrode connecting portion 2b is the same as that in the first embodiment. Individual electrode tip 3a
Are both side edges 4R, 4L of the strip heating resistor 4 in the sub scanning direction.
This is different from the first embodiment in that the shape of a bent portion 3b which is orthogonal to both side edges 4R and 4L and is formed in the middle between the both side edges 4R and 4L is formed obliquely at a position intersecting with. In the second embodiment as well, similar to the first embodiment, the white straight line does not occur.

(Embodiment 3) FIG. 4 is a plan view showing Embodiment 3 of the thermal head of the present invention. In the description of the third embodiment, constituent elements corresponding to those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. In FIG. 4, the shape of the common electrode connecting portion 2b is the same as that in the first embodiment. Both side edges 4 of the strip-shaped heating resistor 4
The individual electrode tip portion 3a is continuously inclined between two positions intersecting R and 4L. In the third embodiment as well, similar to the first and second embodiments, the white blank line does not occur.

(Modifications) The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above-mentioned embodiments, and is within the scope of the gist of the present invention described in the claims. Thus, various changes can be made. A modified embodiment of the present invention is illustrated in (H01) below.

(H01) For example, the shape of the common electrode connecting portion or the tip of the individual electrode can be various shapes other than those shown in the embodiments.

[0021]

The thermal head of the present invention having the above-mentioned structure has the following effects (E01) and (E02). (E01) It is possible to improve the feeling of jaggedness that occurs in the diagonal line. (E02) It is possible to prevent the occurrence of white lines due to white spots.

[Brief description of drawings]

1A and 1B show a first embodiment of a thermal head according to the present invention, FIG. 1A is a plan view, and FIG. 1B is a sectional view taken along line BB in FIG. 1A.

FIG. 2 is a plan view showing a coloring pattern when printing is performed according to the first embodiment.

FIG. 3 is a plan view showing a second embodiment of the thermal head according to the present invention.

FIG. 4 is a plan view showing a third embodiment of the thermal head of the present invention.

FIG. 5 is a conventional server using a strip-shaped heating resistor.
5A is an example of a round head, FIG. 5A is a plan view of a main part, and FIG. 5B is a sectional view taken along line VB-VB of FIG. 5A.

FIG. 6 is a plan view showing a coloring pattern when printing is performed by the conventional thermal head. Five

[Explanation of symbols]

X ... Main scanning direction, Y ... Sub scanning direction, 1 ... Insulating substrate, 2 ...
Common electrode, 2a ... Common electrode body, 2b ... Common electrode connecting part, 3 ... Individual electrode, 3a ... Individual electrode tip, 4 ... Band heating resistor, 4a ... Heating element, 4R, 4L ... Band heating resistor Both side edges in the sub-scanning direction,

Claims (1)

[Claims] 1. A common electrode having a strip-shaped common electrode main body extending along the main scanning direction, a plurality of common electrode connecting portions protruding from the main body in a comb-like shape in the sub-scanning direction, and the common electrode connecting portion. Individual electrodes having a large number of individual electrode tips arranged alternately with each other, and a strip-shaped heating resistor extending along the main scanning direction connecting the common electrode connecting portion and the individual electrode tips are formed on the surface of the insulating substrate. A heating element for one printing dot is formed by the strip-shaped heating resistor portion that connects one of the individual electrode tip portions and a pair of common electrode connecting portions arranged on both sides of the one individual electrode tip portion. The following requirements (Y01) to (Y02)
A thermal head characterized by having (Y01)
The heating element has an approximately rectangular outer shape, (Y02)
A position where both side edges of the strip-shaped heating resistor in the sub-scanning direction intersect with the common electrode connecting portion and the individual electrode tip portion,
Be offset in the main scanning direction (X).