JPH0526660B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a thermal head for heat-sensitive recording, in particular,
The present invention relates to a substrate structure for an edge type thermal head in which a large number of heating elements are formed in a row on the end surface of a heating element substrate.

Configuration of Conventional Example and Problems Therewith As is well known, the thermal recording method is applied to various terminal printers as a recording method that is easy to maintain. In particular, recently, in addition to the conventional color development type thermal recording system, a transfer thermal recording system has been developed, and full color recording has become possible with this system.

When performing color recording using a thermal transfer recording method, one of the biggest differences from monochrome recording using a conventional color-forming recording method is the problem of color shift during overlay. FIG. 1 shows the relationship between a thermal head and recording paper used in conventional monochrome recording.

In Figure 1, 1a is image receiving paper (recording paper), 1
b is a transfer paper, 2 is a paper feed roller, 3 is a thermal head, and the thermal head 3 is a heating element substrate 3.
Since the heat generating element array 3b is formed on one of the two main planes of the head a, hereinafter, this type of head will be referred to as a planar thermal head.

In Fig. 1, the transfer paper 1 is moved by the paper feed roller 2.
b Transfer the image receiving paper 1a to the heating element row 3b of the thermal head 3.
When the heating element row 3b is heated in accordance with the image signal while being brought into pressure contact with the image receiving paper 1a and being fed in the direction of the arrow, monochromatic recording can be performed on the image receiving paper 1a.

In FIG. 1, if direct coloring type thermal recording paper is used instead of 1a and 1b, a recording section of a normal thermal recording system is formed.

On the other hand, in a thermal head using the substrate of the present invention, a recording section is formed in the form shown in FIG.

In FIG. 2, the thermal head 5 is constructed by forming a heating element row 5b on one of four surfaces (end surfaces) parallel to the thickness direction of a heating element substrate 5a.

Hereinafter, the head having the configuration shown in FIG. 2 will be referred to as an end-face type thermal head.

As can be seen from a comparison between FIG. 1 and FIG. 2, in the monochrome thermal transfer recording system, the recording section can be configured so that the recording state can be seen somewhat earlier in FIG. 2.

By the way, when performing color recording using the thermal transfer recording method, by using an edge-type thermal head, it is possible to easily configure a recording section that reduces color shift of multicolor transfer dots by the method shown in Figure 3. be able to.

In FIG. 3, the image receiving paper 1b is placed between
In this state, the image receiving paper 1a is pressed against the heating element array 5a of the thermal head 5 via the transfer paper 1b, and as the roller rotates,
Feed the image receiving paper 1b in the direction of the arrow. For example, cyan, magenta, yellow, and black transfer layers (not shown) are placed on the image-receiving paper 1b, with the outer periphery of the paper feed roller as a unit length (within this unit length range,
Each color is applied uniformly). Therefore, color recording can be performed by transferring each color of cyan, magenta, yellow, and black (an operation of heating the heating element according to the image signal) every rotation of the paper feed roller.

In this case, the overlapping position of each color is adjusted by the rotational position of the paper feed roller.

Even if the planar head shown in Fig. 1 is used, the third
It is possible to configure a recording section as shown in the figure. However, in this case, with respect to the surface of the thermal head 3 shown in FIG. 1 where the heating elements are formed, the area other than the area where the heating element array is formed should not come into contact with the transfer paper, image receiving paper, or roller. It becomes necessary.
This limitation is a surprisingly troublesome problem for conventional planar heads. That is, in the conventional planar head, as shown in FIG. 1, a cover 4 is provided on the surface of the heating element substrate 3a on which the heating element rows 3b are formed. This cover is provided for the purpose of mechanically protecting the semiconductor elements connected to each heating element or the lead wires connected to the electrodes of the heating elements to facilitate heating of the heating element array 3a. .

On the other hand, in order to perform color recording using the method shown in FIG. 3, the length of the outer periphery of the roller 2 around which the image-receiving paper is wound must be at least longer than the short side of the recording screen. As a result, in order to configure the recording section as shown in FIG. 3 with a flat head, it is necessary to
must be larger than for a monochromatic recording head, significantly increasing the price of the head.

The above is an example of a comparison of the methods of configuring the recording section of a planar head and an edge head when color recording is performed by the thermal transfer method.

Even from such a simple comparison, the usefulness of the edge type thermal head in the thermal transfer recording system is clear, and in addition to the above, there are various other points in which the edge type head is easier to use than the flat type head. For example, an example of this is that the recording area mentioned above can be viewed more quickly.In addition to ease of use, from the standpoint of head manufacturing, the flatness of the area where the heating element array is formed is better with an edge-type head. It also has the advantage of being easy to secure.

Although there are many other advantages of edge-type heads, most conventional thermal recording systems have been carried out using flat-type heads. this is,
This is because, in general, it has been thought that planar heads are easier to manufacture than end face heads.

Furthermore, the concept of the edge-type head itself is not new; for example, it is similar to a thermal head in which a row of heating elements is formed by a diffusion method on the end face of a rectangular plate of semiconductor silicon, or an edge-type head. For example, a thermal head is also manufactured in which a row of heating elements is formed on the surface of a glass round rod in parallel to the central axis.

FIG. 4 shows an example of the external appearance of the end face type thermal head 6. In Fig. 4, 7 is a plate-shaped heating element board;
A heating element row 8 in which a large number of heating elements are arranged in a row is formed on one end surface of this rectangular substrate 7. The heating element board 7 is fixed with screws 11 between the head base 9 and the cover 10, and further includes a heating element row 8.
Terminals for driving each heating element are taken out by the film lead 12 and led to the connector 14 via the soldering part 13.

The method of electrical connection from the heating element row 8 to the connector 14 is that the semiconductor element connected to the heating element, for example,
Depending on whether a diode, a thyristor, an IC having a shift register/latch transistor, etc. is used, the external appearance of the end-face type thermal head is changed into various shapes in consideration of these connection methods.

By the way, one of the major reasons why the edge-type thermal head shown in FIG. In addition to forming the rows 8, the electrodes of each of these heating elements must be formed so as to lead to the two main planes (7a and the opposite surface) of the heating element substrate 7.

Purpose of the Invention The present invention provides a configuration of a heating element substrate useful for solving problems in forming heating element arrays and electrodes in extremely fine patterns on three sides of such a plate-shaped heating element substrate. The main purpose is to provide.

Structure of the Invention When constructing an end face type thermal head, electrodes for energizing the heating resistor provided on the end face are guided to two main planes, and at this time, an image signal is input to at least one of the main planes. It is necessary to form fine separated electrodes for one side and a common solid electrode for the other side. When forming a layer of electrically insulating material with low thermal conductivity on the end face of an electrically insulating flat plate, two substantially perpendicular edges where the end face intersects with the two main planes are not chamfered. It has been found that surface tension during the formation of the material layer causes a step break at this end, and therefore, the electrode breaks at this point.

The present invention chamfers two substantially perpendicular ends where the end face of an electrically insulating flat plate intersects with the two main planes so that one end has a larger straight or curved shape than the other end, and at least the chamfered portion is chamfered. By forming a layer of an electrically insulating material with a thermal conductivity lower than that of the material of the flat plate on the end surface containing the material, it is possible to eliminate poor electrode formation and to obtain a flat end surface on which the heating element is formed. The present invention provides a configuration of a heating element substrate that can be used.

DESCRIPTION OF EMBODIMENTS In realizing the above configuration, a specific heating element substrate configuration of an embodiment of the present invention is shown below.
FIGS. 5 and 6. It has a substrate end surface 15 and end surfaces 17 and 18 formed by the main planes 16a and 16b of the substrate, and the substrate end surface 15 and the end surface 1
7 and 18, a heating element having a lower thermal conductivity than the substrate material and forming an electrically insulating layer 19; A column 20 is formed. At this time, electrodes for supplying current to the heating element array 20 are led to the main planes 16a and 16b, and at this time, a separate electrode for inputting image signals is provided on at least one of the main planes (for example, 16a). 21, and it is necessary to form a common solid electrode 22 on the other side 16b.

At this time, when the electrically insulating layer 19 having low thermal conductivity and being a glaze layer is formed on the substrate end surface 15 and the end surfaces 17 and 18, the end surface 17 may be chamfered. When is made small, a step or a discontinuous state of the glaze will occur at the boundary between the end surface 17 and the substrate end surface 15 due to the surface tension of the glaze layer, and as a result, disconnection of the separation electrode 21 will easily occur at this portion. ,
It is necessary to increase the chamfering of the end surface 17 to a certain extent.

At this time, if the chamfering of the end surface 18 is increased, the flatness of the substrate end surface 15 will be reduced. This is because when the chamfering of the end surface 18 is increased and a glaze layer is formed, the end surface 15 of the substrate becomes smaller, and the surface tension of the glaze layer formed thereon reduces the curvature of the end surface. This is because it reduces the burden on the body. This is an extremely disadvantageous condition in forming the heating element. Moreover, since the end surface 18 is a solid electrode, even if the chamfering is made small, there is no risk of wire breakage as described above.

As described above, by increasing the chamfering of the end surface on the separation electrode formation side of the heating element substrate and reducing the chamfering of the end surface on the common electrode formation side, defective electrode formation can be improved and the heating element substrate The structure of the substrate for a thermal head for heat-sensitive recording according to the present invention makes it possible to obtain a flat end face that forms a substrate.

In the present invention, the end surfaces 17 and 18 of the heating element substrate are chamfered in a simple straight line, but it goes without saying that they may be chamfered in the shape of an R curved surface.

Effects of the Invention As described above, when chamfering the edge formed by the end face of the heating element substrate and the two main planes of this substrate, different chamfering (one chamfering is larger than the other chamfering) is performed. By doing this, it is possible to give the necessary flatness to the heating element formed on the end surface of the substrate and to eliminate defects in electrode formation, which greatly contributes to the manufacture of end-face type thermal heads. be.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional transfer thermal recording method using a flat thermal head, Figure 2 is a cross-sectional view of a similar recording method using an edge-type thermal head, and Figure 3 is a cross-sectional view of a similar recording method using an edge-type thermal head. An explanatory diagram of the color recording used, FIG. 4 is a diagram showing an example of the external appearance of an edge-type thermal head, and FIGS. 5 and 6 show a specific substrate configuration of an edge-type thermal head according to an embodiment of the present invention. It is a diagram. 15...Substrate end face, 16a, 16b...Main plane of the board, 17, 18...Substrate edge, 19...Thermal and electrical insulating layer with thermal conductivity smaller than the heating element substrate material, 20...Heat generation Body row, 21... separate side electrode, 22... common side electrode.

Claims (1)

[Claims] 1 It has two substantially right-angled ends where the end face of the electrically insulating flat plate intersects with the two main planes, and the end on the side where the separated electrode is formed is larger than the end on the side where the common electrode is formed. A substrate for an edge-type thermal head, characterized in that the end face is chamfered in a straight line or curved shape, and a material layer having electrical insulation properties and a thermal conductivity lower than that of the material of the flat plate is formed on the end face including at least the chamfered part. .