JPS62193846A - Thermal head - Google Patents

Abstract

PURPOSE:To reduce cost and improve quality by forming an electric insulation/ heat accumulation layer on a metal substrate and arranging a thermal resistor and a conductor wire on said layer. CONSTITUTION:A thermal head 10 has four thermal resistors 11-1-11-4, and the thermal resistors 11-1-11-4 and conductor wires 12-1-12-4, 13-1-13-4 are arranged on an aluminum substrate 15 with an electric insulation/heat accumulation layer 14 formed on the upper surface. Because of aluminum used for the substrate 15, it can easily be machined, and is less costlier than a ceramic substrate. In addition, no baking process which causes a warp is provided in a manufacturing line, so that the flatness is exceedingly improved. Further, the substrate is closely adhered and fixed entirely to a radiating plate 19 acting as a base. Therefore, if the pressing force of a platen worked during the operation of a thermal head, the substrate will not flex and the generation of cracks of a protective film 20 attributable to the flexure be prevented.

Description

[Detailed Description of the Invention] [Summary] A thermal head in which the substrate is made of metal instead of ceramic, and an electrical insulation/heat storage layer is formed on the metal substrate.
A heat generating resistor and a conductor wire are arranged on top of this, making it possible to reduce costs and improve quality.

(Industrial Field of Application) The present invention relates to a thermal head, and particularly to an improvement of a substrate for a thermal head.

[Conventional technology]

In the conventional thermal head, as shown in FIG. 6, a glass heat storage layer 2, a resistor 3, conductor wires 4a, 4b, and a protective film 5 are laminated on a ceramic substrate 1. It has a configuration fixed on a heat sink 6. A portion of the resistor 3 on the upper surface of the heat storage layer 2 between the conductor wires 4a and 4b is the heating resistor portion 7. When an electrical pulse is applied through the conductor Fl 148, it flows along the path shown by the arrow, and the heating resistor 7 generates heat. The electrical pulse falls from the conductor wire 4b to ground.

A plurality of heat generating resistor parts 7 are arranged in parallel in a direction perpendicular to the plane of the paper in FIG. There is. Resistor 3
is extremely thin, conductive in the thickness direction, and has electrical resistance in the planar direction. The plurality of conductor wires 4a are electrically insulated from each other by a ceramic substrate 1 having electrically insulating properties.

Further, the right end side of the conductor wire 4b is connected and serves as a common conductor.

[Problem that the invention seeks to solve]

By the way, the ceramic substrate 1 is manufactured by firing a green sheet, and has the problems of high manufacturing cost, and generally being easily warped and having poor flatness. Since pressure from the platen is applied to the thermal head during operation, if the ceramic U plate 1 is fixed to the heat sink 6 in a slightly warped state, the ceramic substrate 1 may be warped during operation. There is a dent in the direction of correction, which causes cracks in the protective film 5 and shortens the life of the correction head. Therefore, the substrate is required to be free from warpage, but it is unreasonable to require this from the ceramic substrate, which has a firing process in its manufacturing process.

(Means for Solving the Problems) The thermal head of the present invention includes a plurality of heat generating resistors and a plurality of conductor wires that supply electrical pulses to each heat generating resistor, on the surface of which an electrically insulating/heat storage layer is formed. The structure is formed on a substrate made of gold i.

[Effect]

Since the gold FF substrate is manufactured by machining, it is inexpensive and has good flatness. This reduces the cost of the thermal head and prevents shortening of its life due to cracks in the protective film.

〔Example〕

FIG. 1 is an enlarged perspective view showing the structure near the heat generating resistor part (a) of a thermal head according to a first embodiment of the present invention, and FIG. 2 is a perspective view showing a thermal head according to a first embodiment of the present invention. The plan view of the head, Figures 3 and 4 are shown along the lines ■-■ and I in Figure 2, respectively.
FIG. 3 is a cross-sectional view taken along the line V-IV.

As shown in FIG. 2, the thermal head 10 of this embodiment has, for example, four heat generating resistor parts 11-1 to 11-4. Conductor wire 12-1 that supplies electrical pulses to the heating resistor section
~12-4 and conductor wire 1 dropping electrical pulses to ground
3-1 to 13-4 are arranged corresponding to each heat generating resistor part 11-1 to 11-4.

As shown in FIGS. 1, 3, and 4, the heating resistor ff1
s11-+ ~11-4 and U1 body w212-1 ~ 12-
a, 13-1 to 13-4 have electrical insulation/heat storage layer 1 on the upper surface.
4 is arranged on an aluminum substrate 15 on which a number 4 is formed.

A resistor 16 is formed on the upper surface of the layer 14. The resistor 16 is extremely thin, conductive in the thickness direction, and has electrical resistance in the surface direction, and a part of the resistor 16 is connected to the heating resistor 11-1 described above.
~11-4 is configured.

The conductor wires 12-1 to 12-4 for guiding electrical pulses in the heating resistor parts 11-1 to 11-4 are insulated from each other by the layer 14 described above. The conductors W; A12-1 to 12-4 on the ground side from the heat generating resistor parts 11-1 to 11-4 are connected to the band-shaped part 17. The layer 14 is missing in a portion corresponding to this band-shaped portion 17, and the band-shaped portion 17 is connected to the upper surface of the right edge of the substrate 15 with the resistor 16 sandwiched therebetween. Since the resistor 16 can be conductive in the thickness direction as described above,
The band 17 is made of aluminum! It is electrically connected to the stem plate 15.

In this case, the substrate 15 is made of aluminum, which has low electrical resistance, and is thick, so the electrical resistance value is low. By utilizing the low electrical resistance of the substrate 15, the substrate 15 is used as the common conductor 18.

For example, the electrical pulse that drives the heating resistor 11-1 is applied to the conductor wire 12, as shown by the broken line in FIGS. 1 and 3.
-1 to the heat generating resistor 11-I, passing through the heat generating resistor 11-1 to generate heat, entering the conductor wire 13-1, passing through this and being guided to the strip portion 17, It passes through the resistor 16, reaches the common conductor 18, flows inside this conductor, and falls to ground.

The substrate 15 is fixed onto a heat sink 19 made of aluminum.

Further, since the substrate 15 is made of aluminum, machining is easy, and protrusions 15a having, for example, a trapezoidal cross section are formed in portions corresponding to the heating resistors 11-1 to 11-4. This protrusion 15a allows the thermal head 10 to
Portions corresponding to the heating resistors 11-1 to 11-4 are convex as in the case of FIG. 6.

Further, unlike the ceramic substrate, the manufacturing of the substrate 15 does not require a firing process, and merely machining is sufficient, so it is considerably cheaper than the ceramic substrate, and the thermal head 10 can be manufactured at a lower cost.

Furthermore, since the manufacturing process of the substrate 15 does not include a firing step that causes warping, the substrate 15 does not warp and has a much better flatness than the above-mentioned ceramic substrate. Therefore, the substrate 15 is tightly fixed to the heat dissipation plate 19, which also functions as a base, without forming any gaps therein, and without any gaps over the entire surface.

Therefore, even if a pressing force is applied by Braden during operation of the thermal head, the substrate 15 will not bend. As a result, cracks in the protective film 20 due to bending are eliminated, and the life of the thermal head 10 can be avoided from being unnecessarily shortened, resulting in a long life of the thermal head 10.

Next, the layer 14 will be explained. Layer 14 is layer 14 of substrate 1
Heat-resistant organic material (e.g. polyimide) is used on the entire upper surface of 5.
Coat or print with a thickness of about 5 to 10μ thick to 80 to 12
After baking incompletely at 0℃, polyimide is heated again for 5 to 50 minutes.
It is formed by coating or printing to a thickness of 10 μm and incompletely baking at 80 to 120°C. A positive resist is applied onto the layer 14 formed in this way, and the positive resist and the layer 14 are simultaneously buttered by photolithography, and a portion of the layer 14 along, for example, the right edge of the substrate 15 is removed, and a high temperature ( Bake at about 350℃).

Since layer 14 is thus a double layer of polyimide,
It has both electrical insulation function and heat storage-like ability.

The electrical insulation function electrically insulates the conductor wires 12-1 to 12-4. In addition, the thermal conductivity of polyimide is lower than that of glass at about 1710, and the amount of heat is 1 less than that of glass. is increased compared to the conventional case, the thermal efficiency is improved, and the power consumption of the thermal head 10 can be lowered compared to the conventional case.

The resistor 16 has an adhesive layer (Cr) on the surface of the layer 14 for about 50 minutes.
After forming the insulating layer (S!Oz>), it is formed.

Overlapping the resistor 16, conductor wires 12-1 to 12-4.13
-13-4 to -+, a strip portion 17, and a protective film 20 are formed.

Next, the use of the aluminum substrate 15 as the common conductor 18 will be explained.

If the resistance value of the common conductor is large, it will cause a voltage drop, and if the number of heat generating resistors 11-1 to 11-4 that are driven simultaneously increases, the voltage drop will increase, and the heat generation of the individual heat generating resistors will decrease, resulting in printing problems. becomes thinner. Therefore, the density of the print changes depending on the number of heat generating resistors that are driven simultaneously, and the print quality becomes unstable.

Therefore, in order to stabilize printing quality, it is necessary to reduce the resistance value of the common conductor.

The common conductor of a conventional thermal head is a layered portion (corresponding to the strip 17 in FIG. 3), not indicated by reference numeral 8 in FIG. 6, and is made wider or thicker in order to reduce the resistance value. was. If the width is increased, the size of the thermal head becomes correspondingly larger, and if the thickness is increased, the cost increases. Moreover, since the common conductor 8 is a layer, it cannot be expected to sufficiently reduce the resistance value in any case, and the instability of printing quality cannot be satisfactorily resolved.

In this embodiment, the common conductor 18 is not a layer part;
Since the substrate 18 is made of aluminum, its resistance value is much lower than in the past, and the voltage drop is also small. Therefore, the heat output of each driven heat generating resistor section is approximately constant regardless of the number of heat generating resistive sections driven simultaneously, and the density of the print is also constant, resulting in stable print quality.

Moreover, the dimension W extending to the right side of the heating resistor parts 11-1 to 11-4 in FIG. 2 can be made small, and the thermal head 10 can be made smaller.

FIG. 5 shows a thermal head 3 according to a second embodiment of the present invention.
Indicates 0. In the figure, the same components as those shown in FIG. 3 are denoted by the same reference numerals, and the explanation thereof will be omitted.

In the thermal head 30, the flattening layer 31 is connected to the conductor wire 12-1.
~12-4, 13-+, 13-4 and resistor 1
The thermal head 10 is the same as the thermal head 10 described above except that an insulating film 2OA is formed on the upper surface of the flattening layer 31.

The flattening layer 31 is formed by forming the conductor wires 12-1 to 12-4 and 13-4 to 13-4, and then using a silicon-based hard coat material (Si having OH groups attached thereto is dehydrated and condensed by heat). Shino: Si(OH)4→S i 02 +2l-1
20) by dip coating and firing at about 400°C. Since this silicone-based hard coat material has a viscosity close to that of water, it accumulates in the recess 3 of the heating resistor section 11-1 and the recess 32 between adjacent conductor wires.
Unevenness is flattened. The 1Fr12OA is formed on the upper surface of this flattening layer 31, and this surface also becomes a flat surface without any irregularities.

According to this thermal head 30, since the surface is flattened, cracks that allow entry of moisture, ions, etc. are less likely to occur on the surface, and the life of the thermal head 30 is extended. Moreover, in particular, since there are no recesses in the printed area, heat conduction to thermal paper, ink film, etc. is improved, and a coloring temperature can be obtained with less power than conventionally, thereby reducing power consumption.

Further, the flattened Wi 31 can be formed using an aluminum-based hard coat material in the same manner as above, and has the same effect as above.

Moreover, a similar effect can be obtained by using a substrate made of another metal or alloy instead of the aluminum substrate 15.

Further, since the substrate 15 is made of metal and can be machined, it can be formed into a desired shape with high precision.

〔Effect of the invention〕

As described above, according to the present invention, since the substrate is manufactured by machining and made of metal without going through a firing process, etc., firstly, the substrate is inexpensive, and the cost of the thermal head is reduced. Second, the flatness of the board can be guaranteed, and therefore the adhesion of the board to the heat sink can be ensured, and the board will not be repeatedly bent due to the pressing force it receives during operation. As a result, the occurrence of cracks in the protective film can be prevented, and inconveniences such as unduly shortening the life of the thermal head can be prevented, and quality can be improved.

[Brief explanation of drawings]

FIG. 1 is an enlarged and cross-sectional perspective view schematically showing the structure near the - heating resistor of a thermal head according to the first embodiment of the present invention, and FIG. 2 is a schematic perspective view of the structure of the thermal head according to the first embodiment of the present invention. A plan view showing the glue head with the protective film removed, Figure 3 is shown in Figure 2 - ■
FIG. 4 is an enlarged cross-sectional view along line IV-IV in FIG. 2, FIG. 5 is a cross-sectional view of the second embodiment of the present invention, and FIG. 6 is a conventional view. FIG. 2 is a cross-sectional view of an example of a thermal head of FIG. 1 to 5, 10.30 is a thermal head, 11-+, 11-4 is a heating resistor, 12+,
12-4, 13-+, 13-4 are conductor wires, 14 is an electrical insulation/heat storage layer, 15 is an aluminum substrate, 16 is a resistor, 17 is a strip, 18 is a common conductor, 19 is a heat sink, 20 31 is a protective film, and 31 is a flattening layer.

Claims (3)

[Claims] (1) A plurality of heat generating resistor parts (11-_1 to 11-_4) and a plurality of conductor wires (12-_1 to 12-_4) supplying electrical pulses to each heat generating resistor part (11-_1 to 11-_4).
) is formed on a metal substrate (15) having an electrically insulating/heat storage layer (14) on its surface. (2) The thermal head according to claim 1, wherein the metal substrate (15) is used as a common conductor (18). (3) The plurality of heat generating resistor parts (11-_1 to 11-_4
) and the plurality of conductor wires (12-_1 to 12-_4) are coated with a silicon-based or aluminum-based hard coat material on their upper surfaces, and are coated with a flattened layer ( 31) The thermal head according to claim 1, characterized in that it has: