JP2577920Y2 - 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 used in a thermal printer, and more particularly to a thermal head which can function well as either a thermal transfer type or a thermal type.

[0002]

2. Description of the Related Art An example of a conventional thermal head for a thermal printer is shown in FIG.

First, the conventional thermal head shown in FIG. 8 will be described. The thermal head of FIG. 8 is particularly suitable for a thermal transfer type.

[0004] A heat insulating layer 2 made of a material such as glass is formed on a part of the surface of a substrate 1 made of an insulating material such as alumina, that is, on a heating element row forming region. The heat insulating layer 2 has a two-step projection shape in which a substantially trapezoidal projection 2B is attached to the top of the upper surface of a base 2A having an arc-shaped cross section. On the substrate 1 and the heat insulating layer 2, Ta-
A plurality of heating resistor layers 3 made of a SiO ₂ film or the like; a conductor layer 4 made of an Al film or a Cr / Cu two-layer film and selectively supplying power to each heating resistor layer 3; Are sequentially laminated.

When a current flows from the outside to the conductor layer 4, a current flows to the heating resistor layer 3, and the heating element 6 which is an exposed portion of the heating resistor layer 3 located on the protrusion 2 B of the heat insulating layer 2 is formed. The heat is generated, and heat energy is applied to the ink ribbon 43 that comes into contact with the heating element 6.

Next, the reason why the thermal insulation layer 2 of the thermal head shown in FIG. 8 suitable for the thermal transfer type has a two-step projection shape will be described.

In the case of the thermal transfer type, there are various types of paper to be printed, and there are papers having a smooth surface such as dedicated paper for thermal transfer, copy papers, and papers having a rough surface called bond paper. Such rough paper is called rough paper, but it is difficult to perform high-quality thermal transfer printing on rough paper. Therefore, improvements have been made to thermal heads and ink ribbons. For thermal heads, it is best for rough paper printing to have a heating element protruding from the surroundings and to be shaped so that a concentrated load acts on the ink ribbon. I understood. This is the reason for the two-step protrusion shape of the heat retaining layer 2.

[0008]

On the other hand, a feature of this type of thermal printer is that high quality printing can be performed even when the ink ribbon is removed and thermal paper that develops color by heat is used.

That is, with the spread of facsimile, heat-sensitive paper has become available at a low cost. Recently, the number of users who use thermal paper for printing on a thermal linter suitable for thermal transfer has been increasing.

However, the coating film applied to the thermal paper contains particles having high hardness, and during printing, the protective layer 5 of the thermal head may be significantly worn by the particles having high hardness. In particular, in the case of a thermal head for a thermal printer suitable for thermal transfer, which achieves high printing quality, since the heating element 6 has an extremely protruding shape,
The degree of wear by the thermal paper is remarkable. For this reason, if the thermal printing is continued, abrasion of the protective layer 5 on the heating element 6 of the heating resistor layer 3 progresses, and the heating resistor layer 3 is exposed, which may lead to disconnection of the heating resistor layer 3. Frequently, the printing life is impaired.

SUMMARY OF THE INVENTION In view of the foregoing, an object of the present invention is to provide a thermal head which can function well as either a thermal transfer type or a thermal type.

In order to achieve this object, the present inventors have gradually reduced the height (h in FIG. 8) of the two-step projection of the heat retaining layer 2 in the thermal head suitable for the thermal transfer method described above. The printing quality when using thermal paper and the printing life due to thermal paper wear were determined. The following table shows the results.

[0013] In this table, the protrusion height h = 10 μm is a standard value in a conventional thermal head. If the protrusion height h is this value, the print quality is good not only in thermal transfer printing but also in thermal printing. However, the print life of 15 million characters in thermal transfer printing is only 2 million characters in thermal printing. Further, as the height h of the protrusion was reduced, the printing life was increased, and the target life was reached when the height h of the upper stage was 2 μm or less. On the other hand, the print quality hardly changed, and the height of the upper step h = 0 μm (only the base 2A whose upper surface has an arc-shaped cross section)
Was good in the case of

[0014] These phenomena are interpreted as follows.

First, the reason why the print quality of thermal printing does not decrease even when the height of the protrusions is reduced is that the pressure contact of the heat generating portion of the thermal head becomes particularly large because the sensitivity of the thermal paper is higher than that of the ink ribbon. However, it is considered that the color develops sufficiently. The longer print life is due to the reduced wear of the protective layer of the thermal head.The lower the protrusion height, the larger the contact area of the thermal paper on the thermal head and the less the concentration of pressure contact. it is conceivable that.

[0016]

According to the thermal head of the present invention, a heat insulating layer is partially formed on a heat generating element row forming area of a substrate, and a plurality of heat generating elements are arranged on the heat insulating layer in an aligned manner. In a thermal head formed with element rows,
It two said heat generating element array to be used for selectively printing
Provided by the heat insulating layer is, before the heating element array of the one
Serial form arc-shaped cross section of the upper surface of one of the heat insulating layer, is characterized in that the heating element array of the other formed on the projections of the heat insulating layer which is attached to the top of the arcuate section of the upper surface of the other heat insulating layer I have.

[0017]

According to the present invention, when performing thermal transfer printing, printing is performed by a row of heating elements provided with protrusions on the top of the arc-shaped upper surface of the heat insulating layer, thereby achieving adhesion to rough paper. Is good, and high-quality printing can be performed.

Further, when performing the thermal printing, the wear of the protective layer can be minimized by performing the printing using the heating element array having the upper surface having an arc-shaped cross section.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in the drawings. Note that the same or corresponding components as those of the above-described conventional device are denoted by the same reference numerals in the drawings, and only those components that are particularly necessary will be described.

FIG. 1 is a plan view showing an embodiment of a thermal head according to the present invention. In FIG. 1, eight heating elements are shown for simplicity, but the number of heating elements is eight in FIG. It is not limited to an individual.

In FIG. 1, the thermal head of FIG.
Separate heat insulation layers located at both left and right ends of substrate 1
It has a pair of heating element arrays 7a and 7b formed on the elements 2 and 2 , and these two heating element arrays 7a and 7b are arranged in parallel with each other.

The heating element array 7a is suitable for heat-sensitive printing. As shown in FIG. 2, the heat insulating layer 2 at the left end of FIG. The upper surface is formed to have an arcuate cross section, and the heating elements 6a1, 6a2,... Also,
The heating element array 7b is suitable for thermal transfer printing. As shown in FIG. 3, the heat insulating layer 2 at the right end of FIG. 1 for forming the heating element array 7b has an arc-shaped cross section. The heat-generating elements 6b1, 6b2,... Are formed on the protrusions 2b of the heat-retaining layer 2 by forming substantially trapezoidal protrusions 2B on top of the upper surface of the base 2A. The first heating elements 6a1 of the heating element row 7a and the first heating elements 6b1 of the heating element row 7b are connected by connection electrodes 8. Hereinafter, similarly, the heating element row 7a and the heating element row 7b
The heating elements 6a and 6b corresponding to each other are connected by a connection electrode 8.

On each of the connection electrodes 8, an interlayer insulating layer 9 having a substantially square shape is laminated. Further, on the substrate 1, a plurality (12 in this embodiment) of terminal electrodes 11, 12, 21, 22, 31 to 31 extending in a direction substantially perpendicular to the extending direction of each connection electrode 8. 38 are formed. The terminal electrodes 31 to 38 extend over the interlayer insulating layer 9 and are connected to the corresponding connection electrodes 8 by interlayer connection portions 14 respectively. That is, the terminal electrode 31 extends over the interlayer insulating layer 9, and the first connection electrode 8 and the first terminal electrode 31 are connected by the interlayer connection part 14. Hereinafter, similarly, each connection electrode 8 and terminal electrode 3
2 to 38 are connected to each other by the interlayer connection portion 14.

Further, one end of the common electrode 16a of each heating element 6a constituting the heating element row 7a is directly connected to the terminal electrode 11, and the common electrode 16a
Is connected to the terminal electrode 12 extending over the interlayer insulating layer 9 by an interlayer connecting portion 15.
Similarly, one end of the common electrode 16b of the heating element array 7b is directly connected to the terminal electrode 21, and the other end of the common electrode 16b extends over the interlayer insulating layer 9. It is connected to the terminal electrode 22 by the interlayer connection part 15. Note that the connection electrode and the terminal electrode may be arranged upside down with the interlayer insulating layer 9 interposed therebetween.

FIG. 4 is a schematic diagram showing the connection between the thermal head of FIG. 1 and an external electric circuit. In FIG. 4, the heating elements 6a and 6b of the heating element rows 7a and 7b are indicated by symbols of electric resistance. The terminal electrodes 11, 12, 21, 22, 31 to 38 are denoted by the same reference numerals as those in FIG. Of these, the terminal electrodes 31 to 38 have switches S1 to S8 respectively corresponding thereto.
Are connected to each other, and the switches S1 to S8 cause the respective heating elements 6a, 6b of the heating element rows 7a, 7b to be connected.
ON and OFF of the current to the power supply are controlled.

A power supply 18 is connected in parallel to each of the switches S1 to S8. The power supply 18 is connected to the terminal electrodes 11, 12;
1 and 22 are connected. This changeover switch S9
Is for selectively energizing only one of the heating element arrays 7a or 7b to correspond to a printing mode (thermal transfer printing mode or thermal printing mode) in a thermal printer.

For this reason, the switching of the changeover switch S9 is electrically interlocked with the attachment and detachment of the ink ribbon cassette used for thermal transfer printing with respect to the carriage. When the ink ribbon cassette is mounted on the carriage, the switch S9 is connected to the terminal. b9, a current flows through the heating element array 7b for thermal transfer printing. On the other hand, when the ink ribbon cassette is removed from the carriage, the switch S9 is automatically connected to the terminal a9, and a current flows to the heating element array 7a for thermal printing. Each of the switches S1 to S9 merely shows a function, and each of the switches S1 to S9 is actually a switching circuit formed of an electronic circuit.

FIGS. 5 and 6 are schematic diagrams respectively showing the positional relationship between the thermal head and the print medium in the above-described embodiment.

FIG. 5 shows the case of thermal printing.
The thermal head 40 is positioned so as to be inclined with respect to the surface of the platen 41 so that only the thermal printing heating element array 7 a of the thermal head 40 of this embodiment contacts the thermal paper 42. For this reason, the thermal head 40 is supported by a carriage (not shown) so as to be able to rotate in the horizontal direction, and is connected to a driving means such as an actuator (not shown), and a ribbon cassette (not shown) for the carriage. The drive means rotates the thermal head 40 in accordance with the mounting and dismounting of the thermal head 40, and performs the positioning thereof.

FIG. 6 shows the case of thermal transfer printing. As described above, when the ribbon cassette is mounted on the carriage, the thermal head 40 is automatically rotated and its inclination is reversed.
The heating element array 7 b for thermal printing comes into contact with the ink ribbon 43, and the ink of the ink ribbon 43 is transferred and printed on the paper 44. Further, when the ribbon cassette is removed from the carriage, the thermal head 4 is driven by the driving means.
The inclination of 0 automatically returns to the state of FIG. 5 and switches to the thermal printing mode.

The switching of the heating element arrays 7a and 7b is performed by the driving means mounted on the carriage, but can be performed by a configuration as shown in FIG.

In FIG. 7, a carriage 45 is provided on a thermal head mount 4 for holding a thermal head 40.
6 is supported via a support pin 47 so as to project in the direction of the platen 41 and rotate in the horizontal direction. A lever 48 is rotatably supported by the support pin 47. The carriage 48 is reciprocated in a direction indicated by an arrow in FIG. 45 protrudes to the side.
Further, the carriage 45 has a pair of stoppers 50 for limiting the rotation range of the lever 48 to about 90 degrees.
a, 50b are planted.

A compression coil spring 51 is interposed between the thermal head mounting base 46 and the lever 48. The lever 48 is operated by one of the stoppers 50a or 50 by the action of the compression coil spring 51.
b, and the thermal head 40 is mounted on one of the stoppers 50a
Alternatively, by being pulled by the lever 48 stopped in contact with 50b, one of the heating element rows 7a or 7b is held in an inclined state so as to press against the platen 41.

Therefore, one of the stoppers 50
The print mode is switched so that either one of the heating element rows 7b or 7a is pressed against the platen 41 by rotating the lever 48 that is in contact with the other stopper 50b or 50a. Will be done.

On the other hand, the carriage 45 during printing
A pair of arms 52a and 52b for pushing the lever 48 are disposed so as to be opposed to each other at a position beyond the moving range of. Among them, the arm 52a is for rotating the lever 48 which is in pressure contact with the stopper 50b so as to press in contact with the stopper 50a to switch to the heat-sensitive mode in order to hold the thermal head 40 in the thermal transfer mode. The arm 52b switches the lever 48 pressing against the stopper 50a so as to press against the stopper 50b to switch to the thermal transfer mode in order to hold the thermal head 40 in the thermal mode.

According to such a configuration, by attaching / detaching the ribbon cassette to / from the carriage 45, the carriage 45 approaches the one arm 52a or 52b only once, and the lever 48 is rotated by the arm 52a or 52b. And the print mode is switched.

In the thermal transfer printing mode shown in FIG. 6, since it is necessary to wind up the ink ribbon at the portion provided for printing, printing is performed only when the thermal head 40 is moving in the direction of arrow b. Can't do it.
Therefore, this thermal transfer printing mode is one-way printing. On the other hand, when the mode is switched to the thermal printing mode shown in FIG. 5, it is not necessary to wind up the ink ribbon in this thermal printing mode, so that printing is performed while the thermal head 40 is moving in both directions of arrows d and e. This allows bidirectional printing. Therefore, according to the thermal printing mode, printing can be performed at twice the speed of the thermal transfer printing mode.

According to the above-described embodiment, when performing the thermal transfer printing, the printing is performed by the heating element array 7b having the protrusion 2B provided on the top of the base 2A having the arc-shaped upper surface of the heat insulating layer 2 and having the top. Also, the adhesiveness becomes good even on rough paper, and high quality printing can be performed.

Further, when performing the thermal printing, the wear of the protective layer 5 can be minimized by performing the printing by the heating element array 7a having the upper surface of the heat insulating layer 2 having an arc-shaped cross section. Therefore, it can function well as either the thermal transfer type or the thermal type, and can maintain a long life.

The present invention is not limited to the embodiment described above, and various modifications can be made as necessary.

[0041]

As described above, according to the present invention, the heat transfer heating element array and the heat transfer heating element array are switched in accordance with the print mode, so that both the heat transfer type and the heat sensitive type can be used. An excellent effect of being able to function well and maintaining a long life can be achieved.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a thermal head of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG. 1;

FIG. 4 is a circuit diagram schematically showing the electric wiring shown in FIG. 1;

FIG. 5 is an explanatory diagram showing a state of a thermal printing mode in the embodiment of FIG. 1;

FIG. 6 is an explanatory diagram showing a state of a thermal transfer printing mode in the embodiment of FIG. 1;

FIG. 7 is a plan view showing a specific configuration of a print mode switching in the embodiment of FIG. 1;

FIG. 8 is a longitudinal sectional view showing a thermal head suitable for conventional thermal transfer printing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Heat insulation layer 2A Base 2B Projection 3 Heating resistor layer 4 Conductor layer 5 Protective layer 6a, 6b Heating element 8 Connection electrode 11, 12, 21, 21, 31-38 Terminal electrode 14, 15 Interlayer connection part 16a, 16b Common electrode 18 Power supply 40 Thermal head 41 Platen 42 Thermal paper 43 Ink ribbon 44 Paper 45 Carriage 46 Thermal head mount 48 Lever 50a, 50b Stopper 51 Coil spring 52a, 52b Arm

Claims (1)

(57) [Scope of request for utility model registration] 1. A thermal head comprising a heat-insulating layer partially formed on a heat-generating element array forming region of a substrate, and a heat-generating element array in which a plurality of heating elements are arranged in an array on the heat insulating layer. The two heating element arrays selectively provided for printing are provided on different heat insulating layers , respectively , and the one heating element array is formed on the upper surface of the one heat insulating layer having an arc-shaped cross section, and the other is formed. thermal head is characterized in that the heating element array formed on a projection of the insulation layer which is attached to the top of the arcuate section of the upper surface of the other of the heat insulating layer of.