JPH07125283A - Thermal head - Google Patents

Abstract

PURPOSE:To provide a low-cost thermal head which can be easily manufactured and in which no white striping occurs. CONSTITUTION:A thermal head comprises a plurality of boards 2, 2' in which a plurality of heat generating resistor layers 1a, 1b, 1a', 1b' one ends of which are connected to extended electrode layers 3a, 3b, 3a', 3b' extended from common electrode layers 3, 3' and the other ends of which are connected to individual electrode layers 3a, 4b, 4a', 4b' in a column state are formed in a column state and which are seamed along the columns of the layers 1a, 1b, 1a', 1b' to be disposed in a lateral column. Forming widths of the layers 3a, 3b, 3a', 3b' and/or the layers 4a, 4b, 4a', 4b' to be connected to the layers 1a, 1b, 1a', 1b' of at least the boards 2, 2' near a seam 5 of the boards 2, 2' are narrowed from those of the layers 3a, 3b, 3a', 3b' and the layers 4a, 4b, 4a', 4b' to be connected to the other layers 1a, 1b, 1a', 1b'.

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 constructed by joining a plurality of substrates.

[0002]

2. Description of the Related Art Generally, relatively large thermal heads used in printers, plotters, facsimiles, etc. used for output terminals of OA equipment, CAD equipment, etc. are arranged in rows so as to join a plurality of substrates. It will be.

Conventionally, in this type of thermal head, as shown in FIG. 4, a plurality of heating resistor layers connected to the extended electrode layers extended from the common electrode layer and the individual electrode layers are arranged in a line. A plurality of substrates 12 are formed by arranging them to form the heat generating layer 11 and forming a glass protective layer so as to cover the heat generating layer 11.
The heating layers 11 are arranged in a row on a common supporting member so that the heating layers 11 are aligned in a straight line, and the heating resistor layers provided on the respective substrates 12 are heated to form a transfer target such as thermal paper. It is to transfer printing, patterns, etc.

[0004]

As described above, since the above-mentioned conventional thermal head is constructed by joining the substrates together, one of the biggest problems is that at the joint portion, the portion where the joint portion is straddled. There are white streaks that occur when printing is performed. That is, if the boards are not joined together without a gap,
At the joint, the gap between the heat generating resistor layer at the end of the substrate and the heat generating resistor layer at the end of the substrate adjacent to the joint causes a gap in the heat generating resistor layer. When printing or the like is performed at a position across the discontinuity of the heating resistor layer, a white streak, which is an unprinted portion, is inevitably generated on the printed body obtained therefrom. However, it is extremely difficult at present to join the substrates together so that the white stripes are visually negligible.

In order to solve the problem of white streaks due to this gap, for example, as shown in Japanese Patent Laid-Open No. 2-72967, as shown in FIG. Proposed is a method of providing an overlapping portion a of the heat generating layer 11 by combining them so that the heat generating layer 11 is in a continuous state when used, when viewed from the paper feeding direction of the thermal paper or the like that is the transfer target. .

However, in addition to the gap at the seam portion of the substrate, the occurrence of the white stripes has another main factor such as a step generated at the seam portion. That is,
When the substrates are joined together, the upper surface of the uppermost glass protective layer (contact surface with the transferred material) provided on the substrates is placed at the same height at the joints at the joints. If there is no step, that is, there is a step, as shown in FIG. 6, for example, when printing is performed using the thermal paper 13, the heating resistor layer at the seam side end of the substrate 12 whose upper surface is lower at the seam of the substrate 12 A non-contact portion 14 is formed between the upper glass protective layer and the thermal paper 13, and heat is not transmitted to the thermal paper 13 at this portion, and white stripes are also generated on the obtained printed body. Such a step is caused by variations in the thickness dimension and surface roughness of the substrate and layers formed on the substrate such as the heating resistor layer and the glass protective layer. White streaks caused by the step at the seam of the substrate However, it is known that this occurs when the step difference is about 5 μm or more, and when the step difference exceeds about 7 μm, the quality becomes poor.

When a step is formed at the seam portion of the substrate as described above, even if the end portion of the substrate is inclined and the overlapping portion of the heating resistor layers is provided as described in the above publication, white stripes still occur. To do.

Therefore, in order to correct this step, for example, Japanese Utility Model Laid-Open No. 59-59345 proposes a method of adjusting the height by pushing up the lower surface of the substrate with a screw.
Since the adjustment is performed in an extremely minute range of 5 μm or less, the work is extremely troublesome, and variations occur among workers, and it cannot be said that the method is sufficient for correcting the step.

As described above, in the conventional thermal head, in order to eliminate the generation of white stripes, extremely difficult and complicated work is required, which leads to high cost and makes the thermal head very expensive. I was there.

It is an object of the present invention to provide a thermal head which can be manufactured easily and inexpensively and which does not generate white lines.

[0011]

As a result of intensive studies to achieve the above object, the present inventor has found that in a thermal head constructed by joining a plurality of substrates, a heating resistor layer in the vicinity of the joint. When the width of the electrode layer connected to is made narrower than the width of the electrode layers of other parts,
It is possible to reduce the amount of heat that escapes from the heating resistor layer in the vicinity of the seam and escapes through the electrode layer, and when this heating resistor layer is heated, the temperature can be raised compared to other heating resistor layers, It has been found that heat is generated even in the non-adhesive portion of the transfer-receiving member with the thermal head, which occurs at the joint portion, and white streaks can be eliminated.

That is, according to the present invention, a plurality of substrates each having a row of a plurality of heating resistor layers, one end of which is extended from the common electrode layer and the other end of which is connected to the individual electrode layer, are formed. A sheet
In a thermal head that is spliced along a row of the heating resistor layers and arranged in a row, the extension electrode layer connected to the heating resistor layer of at least one substrate in the vicinity of the seam of each substrate, and And / or the formation width of the individual electrode layer is narrower than the formation width of the extended electrode layer and the individual electrode layer connected to another heating resistor layer.

[0013]

Since the formation width of the electrode layers connected to the heating resistor layers facing each other with the seam portion of each substrate sandwiched is made narrower than the width of the electrode layers connected to the other heating resistor layers, the same voltage is applied. When heat is applied to generate heat, the heat generating resistor layer in that portion can reduce the amount of heat transmitted through the electrode layer and escaping from the heat generating resistor layer as compared with the heat generating resistor layer in other portions, and the heat generating amount can be reduced accordingly. Can be increased.

Since the heat generation amount of the heating resistor layer in the vicinity of the seam of the substrate can be increased in this manner, when transferring such as printing across the seam of the substrate, each substrate facing the seam of the substrate is opposed. The transfer dot size of the heat generating resistor layer at the end of the is increased, and it is possible to reach the non-contact portion between the heat generating resistor layers facing each other across these joints, so that white stripes are visually visible. It can be resolved.

[0015]

EXAMPLES Examples will be shown below to describe the features of the present invention in more detail.

FIG. 1 shows a schematic plan view of this embodiment. Figure 1
In the figure, reference numerals 1 and 1 ′ are dot-based heating resistor layers 1
.. 1b .., 1a '.. 1b' .. is a heating layer formed by arranging in a row, reference numerals 2 and 2'represent a substrate, and reference numeral 5 is a joint portion. 2 is a circle A in FIG.
It is a principal part enlarged view of the part shown by.

The thermal head of this embodiment can be manufactured, for example, as follows.

First, a conductive paste is printed on the upper surfaces of the substrates 2 and 2'made of an insulating material such as alumina.
A plurality of extended electrode layers 3a..3b..3a '.. 3b' .. and a plurality of extended electrode layers 3a..3b..3a .. The individual electrode layers 4a ... 4b ... 4a '... 4b' ...
The extended electrode layers 3a ... 3b ... 3a '... 3b' ...
And individual electrode layers 4a ... 4b ... 4a '... 4b' ...
Are formed so that their tips are arranged alternately.

The heat generating layers 1 and 1'are arranged so that their heat generating resistor layers 1a..1b .., 1a '.. 1b' .. The extension electrode layers 3a..3b .., 3a '.. 3b' .. and the other end is connected to the individual electrode layers 4a..4b .., 4a '.. 4b' .. Body layers 1a ... 1b ... 1
The extended electrode layers or the individual electrode layers are shared with a '... 1b' .. Here, the extended electrode layers 3a..3b .., 3a '.. 3b' .. and the individual electrode layers 4a..4b .., 4a '.. 4b' ..
Was formed on the lower side of the heat generating layers 1, 1 ', but it may be formed on the upper side. If necessary, a heat storage layer made of glass or the like may be provided below the heat generating layers 1 and 1 '.

Next, the heating resistor layers 1a..1b .., 1a '.. 1b' .. A protective layer (not shown) such as glass is provided so as to cover 1, 1 '.

In this embodiment, as shown in FIG.
The extended electrode layers 3a, 3a 'and the individual electrode layers 4a, 4a' connected to one or both of the heating resistor layers 1a, 1a 'facing each other with the joint portion 5 between the substrate 2'and The heating resistor layers are formed with a width narrower than that of the heating resistor layers 1b, 1b 'in the central portions of the substrates 2, 2', for example. The widths of the extended electrode layers and / or the individual electrode layers connected to the heating resistor layers 1a and 1a 'in the vicinity of the heating resistor layers 1a and 1a' that face each other with the joint portion 5 interposed therebetween may be appropriately narrowed. Further, here, both the extension electrode layers 3a, 3a 'and the individual electrode layers 4a, 4a' have a narrow formation width, but either one may have a narrow formation width.

The substrates 2, 2'obtained in this way are
A plurality of the heat generating layers 1 and 1 ′ are fixed and arranged on a common supporting member (not shown) so as to be substantially linear.

In the thus obtained thermal head, when the heating resistor layers 1a ... 1b ... 1a '... 1b' ... are heated, the joint portion 5 of each substrate 2, 2'is sandwiched between them. In one or both of the heat generating resistor layers 1a, 1a 'facing each other, the amount of heat transmitted from the heat generating resistor layers 1a, 1a' through the extended electrode layers and the individual electrode layers and escaping is smaller than that of the other heat generating resistor layers. Since the portions of the heat generating resistor layers 1a and 1a 'that face each other with the seam portion 5 interposed therebetween can have a higher temperature than the other portions, when printing is performed using thermal paper or the like, the printing portion straddles the seam portion 5 above. Even at this time, heat can be applied to the non-contact portion of the thermal paper generated at the seam portion 5 and printing can be performed without white lines.

In the above embodiment, a so-called thick film type thermal head in which each layer is formed by printing is described, but the present invention is also applicable to a so-called thin film type thermal head formed by sputtering.

Further, the formation pattern of each layer such as the heating resistor layer, the common electrode layer and the individual electrode layer is not limited to that of the above-mentioned embodiment, and may be formed in an appropriate pattern. For example, as shown in FIG. 3, a plurality of heating resistor layers 6a ...
.., 6a '.. 6b' .. are arranged in rows, and heating layers 6, 6'are formed on the upper surfaces of a plurality of substrates 7, 7 ', and the heating resistor layers 6a..6b. 6a '... 6b' ... each of a plurality of extending electrode layers 8a .. 8b .., 8a '.. 8b' ..
One of the plurality of individual electrode layers 9a..9b .., 9a '.. 9b' .. Seam part 10
The extension electrode layers 8a and 8a 'and / or the individual electrode layers 9a and 9a', which are connected to one or both of the heating resistor layers 6a and 6a 'facing each other across the other heating resistor layers, are formed in other heating resistor layers. , The heating resistor layer 6 in the central portion of the substrates 7 and 7 ', for example.
The structure may be formed so as to be narrower than that in b and 6b '.

Further, the present invention is as shown in FIG.
The same effects as those of the above-described embodiment can be obtained when applied to a structure having a structure in which the ends of the substrates are inclined is joined.

[0027]

According to the present invention, a thermal head free from white stripes can be easily obtained without the need for careful process control, and the height of the substrate for reducing white stripes can be reduced. Since it can be manufactured without providing a special step such as a step of adjusting, productivity can be improved. Therefore, it is possible to provide a thermal head that is more accurate and less expensive than the conventional one, and further improve the versatility of the thermal head and expand the field of use.

[Brief description of drawings]

FIG. 1 is a schematic plan view illustrating a thermal head of an embodiment.

FIG. 2 is an enlarged view of a main part of a circle A portion of FIG.

FIG. 3 is an enlarged view of a main part around a substrate joint portion in a thermal head according to another embodiment.

FIG. 4 is a schematic plan view of a conventional thermal head.

FIG. 5 is a schematic plan view of another conventional thermal head.

FIG. 6 is a sectional view showing a state in which a thermal paper is brought into contact with a thermal head to perform printing.

[Explanation of symbols]

1, 1 ', 6, 6'Heating layer 1a, 1b, 1a', 1b ', 6a, 6b, 6a', 6
b ′ Heat generating resistor layer 2, 2 ′, 7, 7 ′ Substrate 3, 3 ′, 8, 8 ′ Common electrode layer 3a, 3b, 3a ′, 3b ′, 8a, 8b, 8a ′, 8
b'extended electrode layers 4a, 4b, 4a ', 4b', 9a, 9b, 9a ', 9
b'individual electrode layer 5, 10 seam part

Claims (1)

[Claims] 1. A plurality of substrates, each having one end formed on an extended electrode layer extending from a common electrode layer and the other end formed on a plurality of heating resistor layers connected to an individual electrode layer, In a thermal head, which is spliced along a row of heating resistor layers and arranged in a row, the extension electrode layer and / or the extension electrode layer connected to the heating resistor layer of at least one substrate near the joint of each substrate. Alternatively, the formation width of the individual electrode layer is narrower than the formation width of the extended electrode layer and the individual electrode layer connected to another heating resistor layer.