JP2579642Y2 - 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 thermal head for a thermal recording device used in a thermal printer or a facsimile as an output device of a word processor, a personal computer or the like, and in particular, is arranged alternately in a main scanning direction. The present invention relates to a thermal head in which the connected common electrode connection portion and individual electrodes are connected by a strip-shaped heating resistor.

[0002]

2. Description of the Related Art FIGS. 13 and 14 are views showing an example of a conventional thermal head. FIG. 13 is a perspective view of a thermal head Ho, and FIG. 14 is an enlarged view of a portion XIV in FIG.

In FIGS. 13 and 14, a thermal head Ho for performing thermal recording on a thermal recording paper conveyed along the outer periphery of a platen roll (not shown) includes an insulating substrate 02 adhered to the surface of a support plate 01. I have. This insulating substrate 0
On the two surfaces, a common electrode 03 having a strip-shaped common electrode main body portion 03a extending along the main scanning direction X and a large number of common electrode connection portions 03b protruding in the sub-scanning direction Y from the main body portion 03a in a comb shape. Is formed. Also, the insulating substrate 02
On the surface, a large number of individual electrodes 04 are formed which extend in the sub-scanning direction along Y and are alternately arranged with the common electrode connection portions 03b. The distal end portion (hereinafter, referred to as “individual electrode distal end portion”) 04a of each individual electrode 04 is located between the pair of common electrode connection portions 03b, 03b. The plurality of common electrode connection portions 03b and the individual electrode tip portions 0
4a are connected by a heating resistor 05 having a semi-cylindrical cross section extending in the main scanning direction X. The surface of the insulating substrate 02 on which the common electrodes 03, the individual electrodes 04, and the heating resistors 05 are formed is covered with a wear-resistant layer 06 made of glaze (not shown in FIG. 13).
The surface of the wear-resistant layer 06 that covers the surface of the heating resistor 05 that connects the one individual electrode tip portion 04a and the pair of common electrode connection portions 03b, 03b located on both sides thereof has a printing portion 06a (FIG. 14). Reference) is formed. In the above-described conventional thermal head Ho, the individual electrodes 0
4, a voltage is selectively applied to the heating resistor 05 connecting one selected individual electrode 04 and a pair of common electrode connecting portions 03b, 03b located on both sides of the individual electrode tip portion 04a. An electric current flows, and the heating resistor 05 in that portion generates heat. Therefore, the surface portion of the wear-resistant layer 06 covering the surface of the heat-generating portion of the heat-generating resistor 05, that is, the printing portion 06a
When the heat-sensitive recording paper is pressed against the printing section 06a, the heat-sensitive recording paper that comes into contact with the printing portion 06a develops color and heat recording is performed.

In such a thermal head Ho using the conventional thick film technology, it is difficult to obtain uniform print dots because of the large variations in the width, thickness and composition of the heating resistor. Was. Therefore, the conventional Japanese Patent Application Laid-Open No. 63-27
There is known a thermal head in which the surface of a belt-shaped heating resistor is ground flat as described in JP-A-6562. In this type of thermal head, as shown in FIG. 15, the heating resistor 05 on the belt has a substantially uniform thickness and its upper surface is formed flat. Then, the heating resistor is formed by screen printing, a lift-off method (an opening for forming a heating resistor is formed in a resist layer formed on a substrate surface, and a resistor paste is filled into the opening by screen printing or the like, dried, and ground. (A method of forming a heating resistor by baking after heating).

[0005]

However, the heating resistor 0 formed by using a thick film technique such as screen printing.
5, even if the surface is flattened and the thickness is made uniform,
The calorific value distribution is not uniform due to the variation of the composition components. For this reason, the temperature distribution of the conventional thermal head in which the surface of the belt-shaped heating resistor is ground flat is not uniform, for example, as shown in FIG. FIG. 16 (A)
FIG. 16B is a plan view of one dot of the band-shaped heating resistor 05 having a uniform thickness, and FIG. 16B is a temperature distribution of the heating resistor 05 shown in FIG. FIG.
FIG. 17C is a cross-sectional view of the heating resistor 05 shown in FIG. 16A along the sub-scanning direction Y.

In FIG. 16A, an individual electrode 04 and
A pair of common electrode connecting portions 03b, 03b located on both sides thereof
, That is, a heating resistor for one dot is formed from portions indicated by 05c and 05d. Further, the heating resistor 05 for one dot is provided.
A printed portion 06a for one dot on the surface of the wear layer 06 covering the portions c and 05d is formed from portions indicated by 06ac and 06ad.

[0007] The solid line Tc in FIG.
(A) The temperature distribution of the printing portion 06ac along the Pc-Pc cross section,
The broken line Td in FIG. 16B is the Pd-Pd in FIG.
It is a temperature distribution of the printing part 06ad along the cross section. In addition, To in FIG. 16B indicates the color development start temperature. The hatched portion Fo in FIG. 16A indicates the color temperature range of the printing sections 06ac and 06ad.

As can be seen from FIGS. 16A and 16B, when the thick film technique is used, even if the thickness of the heating resistor is made uniform, both sides of the individual electrode 04 in the main scanning direction X are formed. Printed part 06 on the surface of the wear layer covering heating resistors 05c and 05d
The coloring temperature areas of ac and 06ad are shifted in the sub-scanning direction Y. This is because, when the thick film technology is used, even if the thickness of the heating resistor is formed to be uniform, the resistance values of the heating resistors 05c and 05d on both sides of the individual electrode 04 are not uniform. For this reason, as shown in FIG. 17, there is also variation in the shape of the coloring temperature region Fo of each printing portion 6a for one dot composed of the pair of printing portions 06ac and 06ad.
This is because a plurality of heat spots are generated in each of the printing portions 6a for one dot, and there is a large variation in their positions. Therefore, when printing is performed on the thermosensitive recording paper using the belt-shaped heating resistor 05, there is a problem that it is difficult to obtain print dots having a uniform shape, and that the positions of the print dots vary widely.

The above problem is a problem when expressing stable halftones from low density with a small colored area to high density with a large colored area by controlling the printing energy and adjusting the size of the printing dot. Becomes The present invention has been made in view of the above-mentioned circumstances, and has a subject to be described below in a thermal head using a belt-shaped heating resistor. (A) To make the shape of the coloring temperature area and the position in the sub-scanning direction of each printing portion for one dot of the belt-shaped heating resistor uniform.

[0010]

Next, the configuration of the invention of the present application devised to solve the above-mentioned problem will be described. The components of the present invention include the components of the embodiment described later. To facilitate correspondence, the reference numerals of the components of the embodiment are enclosed in parentheses. The reason why the present invention is described in correspondence with the reference numerals of the embodiments described later is to facilitate understanding of the present invention, and not to limit the scope of the present invention to the embodiments.

The thermal head (H) of the present invention has a strip-shaped common electrode main body (3) extending along the main scanning direction (X).
a) and a common electrode (3) having a plurality of common electrode connection portions (3b) protruding in the sub-scanning direction (Y) from the main body portion (3a) in a comb shape; A large number of alternately arranged individual electrodes (4) and the common electrode connecting portion (3) extending along the main scanning direction (X).
b) In a thermal head in which a strip-shaped heating resistor (5) connecting the individual electrodes (4) is formed on the surface of the insulating substrate (2), the strip-shaped heating resistor (5) is The width in the scanning direction (Y) is periodically changed along the main scanning direction (X) such that the width in the scanning direction (Y) is narrow on the individual electrode (4) and wide on the common electrode connection part (3b). It is characterized by.

[0012]

When printing is performed with the above-described thermal head of the present invention, the individual electrode (4) and the common electrode connecting portions (3) on both sides thereof are used.
b) printing energy (electric power) is applied. In that case, the current flows through the heating resistor between the individual electrode (4) and the common electrode connection (3b) on both sides thereof. However,
In the thermal head of the present invention, the width of the heating resistor (5) in the sub-scanning direction (Y) is narrow on the individual electrode (4) and wide on the common electrode connection part (3b). For this reason, the resistance value of the heating resistor (5) is large near the individual electrode (4) and decreases as approaching the common electrode connection part (3b). The amount of heat generated when current flows through the heating resistor (5) is
When a current flows from the individual electrode (4) to the common electrode connection part (3b) on both sides of the common electrode connection part (3b), a large amount of heat is generated in the vicinity of the individual electrode (4).
b) The calorific value decreases in the vicinity. Therefore, at the time of printing, a heat spot around the individual electrode (4) is generated on the heating resistor (5). The range in which the heat spot occurs is concentrated in the vicinity of the individual electrode (4), so that the range is narrower than in the related art. That is, the variation of the area and the position of the heat spot becomes smaller than before. Therefore, the shape and position of the print dot are made uniform. Then, the temperature distribution on the surface of the heating resistor (5) changes (decreases) continuously from the center of the heat spot toward the outside. And
In such a thermal head, the temperature distribution of the printing portion (the contact portion with the printing paper) becomes the same. In this case, if the printing energy applied to the heating resistor (5) is adjusted, the area of the coloring temperature area (temperature area for coloring the thermosensitive recording paper or the like) of the printing section is reduced by the area of the small heat spot. It changes greatly up to the area. Therefore, for example, when a constant voltage pulse is applied as a printing pulse and energy is controlled by the pulse width, the area of the coloring temperature region changes according to the pulse width.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. In the embodiments, corresponding components are denoted by the same reference numerals. First, an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the thermal head H for performing thermal recording on the thermal recording paper P conveyed along the outer periphery of the platen roll R includes a support plate 1. An insulating substrate 2 is adhered to the surface of the support plate 1 on the left side in FIG. 1 with an adhesive. The insulating substrate 2 comprises a substrate body 2a made of ceramic and an underglaze layer 2b formed on the surface thereof.
On the surface of the insulating substrate 02, a strip-shaped common electrode main body 3a extending along the main scanning direction X and a plurality of common electrode connecting parts 3 protruding in the sub-scanning direction Y from the main body 3a in a comb shape.
A common electrode 3 having b is formed. Further, on the surface of the insulating substrate 2, along the Y in the sub-scanning direction,
A large number of individual electrodes 4 are formed alternately (alternately) with the common electrode connection 3b. The tip 4a of each individual electrode 4 is connected to a pair of the common electrode connecting portions 3b,
It is located in the middle between 3b. The large number of common electrode connection portions 3b and the individual electrode tip portions 4a are connected by a strip-shaped heating resistor 5 extending in the main scanning direction X.

The width of the strip-shaped heating resistor 5 in the sub-scanning direction Y is narrow on the individual electrode 4, and the common electrode connecting portion 3b is formed.
It has a shape that periodically changes along the main scanning direction X so as to be wider above. In the present embodiment, the width on the individual electrode 4 is 40 μm, and the width on the common electrode connection 3b is 14 μm.
It is 0 μm. The surface of the insulating substrate 2 on which the electrodes 3 and 4 and the heating resistor 5 are formed is covered with a wear-resistant layer 6 made of glaze (not shown in FIG. 2). The abrasion-resistant layer 6 covering the surface of the heating resistor 5 that connects the one individual electrode tip portion 4a and the pair of common electrode connecting portions 3b, 3b located on both sides of the tip portion 4a (see FIGS. 3 and 4). And 11) are formed.

A printed wiring board 7 is adhered to the surface of the support plate 1 on the left side in FIG. 1 with an adhesive, and external connection wirings 8 are formed on the surface of the printed wiring board 7. . The external connection wiring 8 is connected to the printed wiring board 7 on the input end side (the left side in FIG. 1).
Is connected to a socket 10 serving as a drive signal input terminal via a lead wire 9 penetrating through. A driving IC is provided on a portion of the printed wiring board 7 close to the insulating substrate 2, and the driving IC is connected to the IC connection terminal 4 b of the individual electrode 4 and the external connection wiring 8 by bonding wires 11 and 12. Is connected to The IC and the bonding wires 11 and 12 are covered with a protective resin 13, and the protective resin 13 is protected by an aluminum cover 14. The thermal head H of the present embodiment includes the components indicated by the reference numerals 1 to 14 and the driving IC.

Next, referring to FIGS. 5A to 10B, FIG.
A method of manufacturing the thermal head H of the present embodiment having the configuration shown in FIGS. 4A and 4B will be described. First,
An organic gold paste (metallo organic gold paste D27 manufactured by Noritake Co., Ltd.) is solid printed on the surface of the insulating substrate 2 composed of the ceramic substrate main body 2a and the glaze layer 2b formed on the surface thereof. Next, after drying and firing, an electrode pattern is formed on the surface of the insulating substrate 2 by photolithography. The electrode patterns formed in this way are shown in FIGS. 5 (A) and 5 (B).
As shown in FIG. 3, the common electrode body 3a having a thickness of 0.3 to 3 m is provided.
And the common electrode 3 having a common electrode connection portion 3b;
And the individual electrodes 4.

Next, as shown in FIGS. 6A and 6B, a photosensitive resist Rs (about 5 to 30 μm thick) is formed on the surface of the insulating substrate 2 on which the electrodes 3 and 4 are formed. Negative photoresist PMERN-H manufactured by Tokyo Ohka Kogyo Co., Ltd.
C60) is applied by spin coating. Next, the photosensitive resist R is exposed and developed with a photomask M thereon. Then, as shown in FIGS. 7A and 7B,
On the surface of the insulating substrate 2, a resist layer (resist pattern) R having a strip-shaped heating resistor forming opening Rh extending in the main scanning direction X is formed. The strip-shaped heat-generating resistor forming openings Rh are periodically arranged along the main scanning direction X such that the width in the sub-scanning direction Y is narrow on the individual electrode 4 and wide on the common electrode connection 3b. It has a changing shape.

Next, as shown in FIGS. 8 (A) and 8 (B), a ruthenium oxide-based heating resistor forming paste Pe (resistor manufactured by Tanaka Massey Co., Ltd.) is formed in the heating resistor forming opening Rh. Paste GZX) and dry.

Next, a portion of the dried paste for forming a heating resistor Pe that protrudes from the opening Rh is wrapped with a wrapping sheet to flatten its surface. Then, as shown in FIGS. 9A and 9B, the opening Rh
An unsintered resistance layer 5a for forming a heating resistor is formed therein. Next, the dried non-sintering resistance layer 5a for forming a heating resistor is sintered at a temperature of 800 to 900 ° C., and the resist layer R is burned.
A strip-shaped heating resistor 5 extending along the main scanning direction X as shown in FIGS. The strip-shaped heating resistor 5 has a shape that periodically changes along the main scanning direction X so that the width in the sub-scanning direction Y is narrow on the individual electrode 4 and wide on the common electrode connection portion 3b. Have. Next, when the entire surface of the insulating substrate 2 on which the electrodes 3 and 4 and the heating resistor 5 are formed is covered with a wear-resistant layer 6 made of glaze, the structure shown in FIGS. 4A and 4B is obtained. Is obtained.

Next, the operation of the thermal head H of this embodiment will be described with reference to FIGS. Driving IC (Fig. 1
When a voltage is selectively applied to the individual electrode 4, a heating resistor that connects between the individual electrode tip 4 a of the selected individual electrode 4 and a pair of common electrode connecting portions 3 b located on both sides thereof is connected. An electric current flows through the body 5, and that portion generates heat.

As described above, the width of the heating resistor 5 in the sub-scanning direction Y is narrow on the individual electrode 4, and
It is wider on the common electrode connection 3b. For this reason, the resistance value of the heating resistor 5 is large in the vicinity of the individual electrode 4 and decreases as approaching the common electrode connection 3b. The amount of heat generated when a current flows through the heating resistor 5 is proportional to the resistance value. Therefore, when a current flows from the individual electrode 4 to the common electrode connection portions 3b on both sides thereof, the amount of heat generated is large near the individual electrode 4, The calorific value decreases near the common electrode connection 3b.

FIG. 11A is a plan view of one dot of the belt-shaped heating resistor 5, and FIG. 11B is along the main scanning direction X of the heating resistor 5 shown in FIG. 11A. FIG. 11 (C) shows the temperature distribution of the heating resistor 5 shown in FIG. 11 (A).
FIG. 2 is a cross-sectional view (a cross-sectional view taken along the line Pc-Pc) along the main scanning direction X of FIG.

In FIG. 11A, F is the individual electrode 4
And a pair of common electrode connecting portions 3b, 3b located on both sides thereof
The figure shows the heating temperature of the printed portion 6a for one dot on the surface of the wear layer 6 that covers the heating resistor for one dot, that is, the heating resistor that connects the heating resistor for one dot. FIG. 11 (B)
Is a temperature distribution along the cross section taken along the line Pc-Pc in FIG. In addition, To in FIG. 11B indicates the coloring start temperature.

As can be seen from FIGS. 11A, 11B and 11C, the color temperature region F of the printing portion 6a on the surface of the wear layer covering the respective heating resistors on both sides of the individual electrode 4. Has a heat spot at its center. Therefore, the temperature of the printing section continuously decreases as going outward with the heat spot as the center. For this reason,
As shown in FIG. 13, the shape of the coloring temperature region F and the position in the sub-scanning direction Y of each printed portion for one dot are uniform. Then, when the thermosensitive recording paper that develops a color at the coloring temperature To or more is brought into contact with the printing portion 6a on the heating resistor 5, the shape of the coloring area (that is, the printing dot) of the thermosensitive recording paper P and the position in the sub-scanning direction Y are changed. And uniformity with little variation. Further, the temperature distribution of the printing portion 6a continuously changes (decreases) as going outward from the heat spot. In this case, when the printing energy applied to the heating resistor is adjusted, the area of the coloring temperature region (temperature region for coloring the thermosensitive recording paper or the like) F of the printing unit 6a changes continuously. Therefore, for example, in the case where a constant voltage pulse is applied as a printing pulse and energy is controlled by the pulse width, the area of the coloring temperature region changes according to the pulse width.

Therefore, the thermal head H of the above embodiment stabilizes the halftone from a low density with a small colored area to a high density with a large colored area by adjusting the printing energy applied to the heating resistor 5. Can be expressed.

Although the embodiment of the thermal head of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, but deviates from the present invention described in the claims for utility model registration. In addition, various small design changes can be made. For example, if the width in the sub-scanning direction Y is
The strip-shaped heating resistor 5 of the embodiment, which has a shape that periodically changes along the main scanning direction X so as to be narrower on the upper side and wider on the common electrode connection portion 3b, is a conventionally known heating resistor. Forming methods, for example, a screen printing method, a lift-off method (a method in which a resistor paste is filled in an opening for forming a heating resistor formed in a resist layer, dried, baked after grinding), and a MOD method (a resistor is formed on the surface of an insulating substrate) (A method of forming a resistor pattern by photolithography after forming a metal organic material layer for formation), or the like.

[0027]

According to the present invention, the width of the strip-shaped heating resistor in the sub-scanning direction is narrow on the individual electrode.
Since the shape is periodically changed along the main scanning direction so as to be wider on the common electrode connection portion, the heat generation amount is large near the individual electrode, and the heat generation amount is small near the common electrode connection portion. Therefore, at the time of printing, a heat spot around the position of the individual electrode is generated on the heating resistor. Since the range in which the heat spot is generated is concentrated near the individual electrode, the range is narrower than in the related art. That is, the variation of the area and the position of the heat spot becomes smaller than before. Therefore, the shape and position of the print dot are made uniform. The temperature distribution on the surface of the heating resistor changes (decreases) continuously with the heat spot as the center and going outward. The same applies to the temperature distribution in the printing portion of the thermal head. In this case, when the printing energy applied to the heating resistor is adjusted, the area of the coloring temperature area (the temperature area for coloring the thermosensitive recording paper or the like) of the printing section increases from the area of the small heat spot to the entire area of the printing section. Change.
Therefore, for example, when a constant voltage pulse is applied as a printing pulse and energy is controlled by the pulse width, the area of the coloring temperature region changes according to the pulse width. Therefore, the thermal head of the present invention can express a stable halftone from a low density with a small colored area to a high density with a large colored area by adjusting the printing energy applied to the heating resistor.

[Brief description of the drawings]

FIG. 1 is an overall explanatory view of an embodiment of a thermal head according to the present invention.

FIG. 2 is a perspective view of a main part of the embodiment.

FIG. 3 is an enlarged view of a section III in FIG. 2;

FIG. 4 is a detailed explanatory view of the portion of FIG. 3;
4 (A) is a plan view, and FIG. 4 (B) is the IVB-IV of FIG. 4 (A).
FIG.

FIG. 5 is an explanatory view of a method of manufacturing the portion shown in FIG. 4; FIG. 5 (A) is a plan view, FIG. 5 (B) is a sectional view taken along line VB-VB in FIG. It is.

6 is an explanatory view of a manufacturing process subsequent to the portion shown in FIG. 5; FIG. 6 (A) is a plan view, and FIG. 6 (B) is FIG.
It is a VIB-VIB line sectional view of (A).

7 is an explanatory view of a manufacturing process subsequent to the portion shown in FIG. 6; FIG. 7 (A) is a plan view and FIG. 7 (B) is FIG.
FIG. 7A is a sectional view taken along line VIIB-VIIB of FIG.

8 is an explanatory view of a manufacturing process subsequent to the portion shown in FIG. 7; FIG. 8 (A) is a plan view and FIG. 8 (B) is FIG.
It is a VIIIB-VIIIB line sectional view of (A).

9 is an explanatory diagram of a manufacturing process subsequent to the portion shown in FIG. 8; FIG. 9 (A) is a plan view, and FIG. 9 (B) is FIG.
FIG. 3A is a sectional view taken along line IXB-IXB of FIG.

10 is an explanatory diagram of a manufacturing process subsequent to the portion shown in FIG. 9; FIG. 10A is a plan view, and FIG. 10B is a cross-sectional view taken along line XB-XB of FIG. FIG.

FIG. 11 is a diagram for explaining the operation of the first embodiment, and FIG.
FIG. 4 is an explanatory diagram of a temperature distribution of a heating resistor for dots in a sub-scanning direction.

FIG. 12 is a diagram for explaining the operation of the first embodiment, showing the shape of the coloring temperature region of the printing unit.

FIG. 13 is a perspective view of a main part of a first conventional thermal head.

FIG. 14 is an enlarged view of an arrow XIV portion of the first conventional example shown in FIG. 13;

FIG. 15 is an explanatory diagram of a second conventional example different from the first conventional example.

FIG. 16 is an operation explanatory view of the second conventional example.
FIG. 4 is an explanatory diagram of a temperature distribution of a heating resistor for one dot in a sub-scanning direction.

FIG. 17 is an operation explanatory view of the second conventional example.
FIG. 3 is a diagram illustrating a shape of a color temperature region of a printing unit.

[Explanation of symbols]

 2 Insulating substrate 3 Common electrode 3a Common electrode body 3b Common electrode connecting member 4 Individual electrode 5 Heating resistor X Main scanning direction Y Sub scanning direction

Claims (1)

(57) [Scope of request for utility model registration] 1. A band-shaped common electrode main body (3a) extending along the main scanning direction (X) and a large number of common electrode connections protruding from the main body (3a) in a comb-like manner in the sub-scanning direction (Y). A common electrode (3) having a portion (3b), and a number of individual electrodes (4) alternately arranged with the common electrode connection portion (3b)
And a strip-shaped heating resistor (5) extending along the main scanning direction (X) and connecting the common electrode connecting portion (3b) and the individual electrode (4) are formed on the insulating substrate (2). In the thermal head formed on the surface, the strip-shaped heating resistor (5) is arranged in the sub-scanning direction (Y).
Is narrow on the individual electrode (4), and the common electrode connection portion (3
b) A thermal head characterized in that it has a shape that periodically changes along the main scanning direction (X) so as to be wider on the upper side.