JP2525171Y2 - Thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thermal head.

[Prior Art] FIG. 12 is a plan view of a typical conventional thermal head 1, FIG. 13 is a cross-sectional view taken along section line XIII-XIII of FIG. 12, and FIG. FIG. 14 is a cross-sectional view as viewed from a section line XIV-XIV of FIG. In the thermal head 1, a heating resistor array 3 is linearly formed near an end of one surface of a head substrate 2 having a length L1 made of an electrically insulating material such as alumina-based ceramic. On the head substrate 2, a driving circuit 4 for selectively driving the heating resistor array 3 to generate heat to perform thermal recording is mounted, and supplies the driving circuit 4 with print data and control signals for thermal recording. Wiring boards 5 are connected to each other, and these are electrically connected to each other by lead wires (not shown) patterned on the head substrate 2. The drive circuit 4 is covered with a protective film 6 such as a synthetic resin material. The surface of the head substrate 2 opposite to the row of heating resistors 3 is made of a metal material having good heat conductivity, such as aluminum, through an adhesive layer 7 by press molding or die casting to have a length L2 (for example, 30 mm). Is adhered to the heat radiating plate 8.

Stopping portions 8a, 8b, 8c for positioning the head substrate 2 are formed at three edges of the heat sink 8 other than the side where the external wiring substrate 5 is arranged. Further, a concave groove 9 is formed in the base end portion of the stopper 8c along the direction in which the heating resistor rows 3 are arranged.

[Problem to be Solved by the Invention] The heat radiating plate 8 of the thermal head 1 of such a conventional example is manufactured using a mold by, for example, press molding or die casting. At this time, due to the aging of the mold used, the portions forming the inner corners of the respective impact portions 8a to 8c of the heat sink 8 are worn. In this case, the corner of the heat sink 8 is formed as a corner 8d shown by a broken line in FIG. 15 until the mold does not change over time. Becomes the inclined portion 8e. Such an inclined part 8e
In this case, the corner 2a of the head substrate 2 is not accommodated in close contact, and the corner 2a is in contact with the inner surface of the stopper 8a and is fixed in a state inclined with respect to the heat sink 8. Such a situation is the same for both of the stoppers 8a and 8b. In such a case, the adhesive generally used for the adhesive layer 7 is an epoxy-based adhesive, and the thermal conductivity α1 α1 of the head substrate 2 is 50 to 70 × 10 ⁻³ [cal / cm · sec · ° C.] .. (1) and the thermal conductivity α2 α2 of the heat sink 8 = 560 × 10 ^-3 [cal / cm · second · ° C] · · · thermal conductivity α3 α3 = 0.1 to 0.5 × 10 ^-3 [cal / cm-second- ℃] …… (3) Relatively small, such as thermal conductivity of air α4 α4 = 0.08 × 10 ^-3 [cal / cm-second- ℃] …… (4) Is known to be very small, though large.

In the conventional example, as shown in FIGS. 13 and 14,
The thickness of the adhesive layer 7 between the head substrate 2 and the heat radiating plate 8 becomes non-uniform along the arrangement direction of the heating resistor rows 3 (the left-right direction in FIG. 13) or becomes excessively thick. Has problems. When the thickness of the adhesive layer 7 is not uniform, the heat generated from the heating resistor array 3 is not transmitted to the heat radiating plate 8 uniformly, and therefore, the heating resistor array 3 has an uneven temperature distribution, and the thermal printing is performed. In this case, the print density becomes uneven. If the thickness of the adhesive layer 7 becomes uneven, the heat from the heating resistor array 3 will not be effectively transmitted to the heat radiating plate 8, and the generated heat will be stored in the head substrate 2. . Due to such heat storage, even under the control without performing thermal printing, for example, undesired thermal coloring may be performed on the thermal recording paper facing the heating resistor array 3, and the printing quality may be degraded.

In order to solve such a problem, there is a technique in which a mold is configured so that a concave groove similar to the concave groove 9 is formed in advance on the inner peripheral surface of the base end portion of the impact portions 8a and 8b in the heat sink 8. Conceivable. According to this, the above-described problem of the conventional example due to the wear of the mold is solved, but on the other hand, the thickness of the adhesive layer 7 near the heating resistor row 3 is increased due to the newly formed groove, There is a new problem that a sufficient heat radiation effect cannot be realized.

An object of the present invention is to solve the above-mentioned technical problems and to provide a thermal head in which printing quality in thermal recording is remarkably improved.

Means for Solving the Problems According to the present invention, an electrically insulating substrate having a plurality of heating resistors arranged on one principal surface close to a side end surface is formed by projecting the side end surface of the substrate to a heat dissipation member. At least one of the side end faces other than the side end face was opposed to the ridge portion at an interval, and was adhered and fixed on the heat radiating member in a state where the side end face was positioned by being brought into contact with a stop formed on the heat radiating member. A thermal head characterized in that:

[Operation] According to the present invention, since the side end surface of the substrate on which the heat generating resistor is disposed in close proximity is opposed to the ridge formed on the heat radiating member with a space therebetween, the substrate is placed on the heat radiating member. When assembling the thermal head by adhering to the substrate, even if the adhesive slightly protrudes from between the lower surface of the substrate and the upper surface of the heat dissipating member, it may be removed from the gap formed between the side end surface of the substrate and the ridge. Can be accommodated. Therefore, appearance becomes good,
Further, by visually confirming that the adhesive uniformly protrudes into the gap, it can be inspected that the bonding state between the substrate and the heat radiating member has been uniformly achieved. Further, since the adhesive is in the gap, the adhesive does not protrude to the outside, so that large dust does not adhere to the adhesive, thereby preventing the recording medium such as thermal recording paper from being conveyed. It will not be.

FIG. 1 is a perspective view of a thermal head 11 according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1, and FIG. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 1. The thermal head 11 is made of, for example, a ceramic such as aluminum oxide Al ₂ O ₃ and has a length L3 and a width W1.
Head substrate 13 formed in a rectangular flat plate shape. A heat storage layer 14 made of, for example, glass is formed on the head substrate 13 in a strip shape, and a resistor layer 15 made of, for example, tantalum nitride Ta ₂ N is formed on the entire surface of the head substrate 13.

A common electrode 16 and a plurality of individual electrodes 17 on the resistor layer 15
Is formed of, for example, aluminum Al, whereby a plurality of heating resistors 18 are linearly formed on a main surface 41 near a side end surface 40 on the head substrate 13.
19 are configured. A wear-resistant layer 20 is formed on the entire surface.

A drive circuit element 21 for selectively energizing the heating resistor array 19 and performing control for performing thermal printing is provided on the head substrate 13.
Above, an external wiring board 22 arranged to be connected to the individual electrode 17 and supplying printing data and control signals for thermal printing to the drive circuit element 21 is connected via a patterned signal line 23. Is done. The external wiring board 22 includes a support film 24 made of a synthetic resin material, and the signal line 23
And the circuit wiring 25 formed so as to be individually connected. The drive circuit element 21 is covered with a protective film 26 such as a synthetic resin material.

The head substrate 13 and the heat radiating plate 12 are bonded by an adhesive layer 27 made of, for example, an epoxy-based adhesive or a pressure-sensitive adhesive. The adhesive layer 27 is formed between the head substrate 13 and the heat sink 12.
In addition to contributing to the fixation, even if there are irregularities on the mutually facing surfaces of the heat sink 12 and the head substrate 13, they are filled and based on such irregularities,
It also has the effect of preventing unevenness in heat conduction from the heating resistor array 19 to the heat radiating plate 12.

In the peripheral portion of the heat radiating plate 12, an outer ridge 28 is formed to surround the mounted head substrate 13 over the remaining area except for the connection area of the external wiring board 22. In the outer ridge 28, a position relatively distant from the heating resistor row 19 when the head substrate 13 is mounted, for example, a portion opposite to the heating resistor row 19 in FIG.
At the time of bonding, the side end 42 of the head substrate 13 which is different from the side end 40 is brought into contact with the head substrate 13 to form a positioning stopper 12a for determining the bonding position in the left-right direction in FIG.

In order to position the head substrate 13 in the vertical direction in FIG. 1, the width of the heat radiation plate 12 is, for example, less than half of the width W2 of the heat radiation plate 12 in the upper end of FIG. Is formed as a positioning stopper 12b with which the upper end of the head substrate 13 in FIG. 1 contacts. In the remaining area of the outer ridge 23, the inner surface of the outer ridge 28 is formed thin so as to be spaced from the side of the head substrate 13.
Also, inside the base ends of the stoppers 12a, 12b, stoppers 12a, 12b
A groove 29 having a width of, for example, 0.5 to 1.5 mm and a depth of 0.3 to 1.0 mm is formed over a range including the formation range of the groove.

FIG. 4 is a simplified sectional view corresponding to FIG. 2 of the thermal head 11, FIG. 5 is a simplified sectional view corresponding to FIG. 3, and FIG. It is an expanded sectional view. In the thermal head 11 having the above-described configuration, the heat sink
In bonding the head substrate 13 to the substrate 12 via the adhesive layer 27, the concave groove 29 can absorb the excess adhesive layer 27, and the adhesive layer 27 between the head substrate 13 and the heat sink 12 Can be reduced as much as possible. As a result, the heat dissipation from the head substrate 13 to the heat radiating plate 12 is improved, and the printing quality can be improved.

When the concave groove 29 is not formed in the heat radiating plate 12, when the thickness of the adhesive layer 27 is reduced at the place where the heating resistor row 19 is formed, the adhesive layer 27 generates heat on the heat radiating plate 12. It moves to the opposite side of the resistor row 19 in the left-right direction of FIG. 1, and the head substrate 13 is inclined with respect to the left-right direction of FIG.
By forming the concave groove 29, such a situation can be prevented.

Further, as described above, in the mold used when the heat sink 12 is manufactured by press molding or die casting, the inner periphery of the base end portion of the outer peripheral ridge 28 including the stoppers 12a and 12b of the heat sink 12 due to aging. The portion of the surface forming the corner 30 shown in FIG. 2 is worn, resulting in an arc-shaped inclined portion as described in the section of the prior art. Even in such a case, the concave groove 29
Accordingly, such an arc-shaped inclined portion does not occur at the base end portions of the impact portions 12a and 12b, and an undesired situation in which the head substrate 13 is lifted up by the inclined portion and inclined can be prevented. Thus, the life of the mold used to manufacture the heat sink 12 can be extended.

In addition, excessive adhesive flows into the concave groove 29, so that it is possible to suppress work accuracy, reduce man-hours, and increase positioning accuracy.

In the thermal head 11 of such an embodiment, the head substrate
The side end 40 near the area where the thirteen heating resistor rows 19 are formed is spaced from the outer ridge 28 of the heat sink 12, and
Even when the inclined portion is formed on the inner surface near the heating resistor row 19 of 28, the vicinity of the heating resistor row 19 of the head substrate 13 is lifted, and the interval between the heating board 12 and the heat radiating plate 12 is increased or this interval is increased. Can be prevented from becoming uneven in the arrangement direction of the heating resistor rows 19. As a result, it is possible to prevent uneven printing in the thermal recording described in the section of the prior art and undesirable heat-sensitive coloring due to the heat storage effect in the head substrate 13, thereby significantly improving the printing quality.

As a modification of the thermal head 11 of the embodiment described above,
As shown in FIG. 7, the configuration may be such that the concave groove 29 is not formed. In such a case, although the adhesive layer 27 becomes non-uniform in the left-right direction in FIG. 7 and the space between the head substrate 13 and the heat radiating plate 12 increases on the side opposite to the heating resistor row 19,
The vicinity of the head substrate 13 where the heating resistor array 19 is formed can be kept in close contact with the heat sink 12. That is, the thickness of the adhesive layer 27 between the portion of the head substrate 13 where the heating resistor array 19 is formed and the heat sink is increased or the thickness is non-uniform in the arrangement direction of the heating resistor array 19. The basic effect of the present invention for preventing the situation described above is achieved.

FIG. 8 shows a thermal head according to still another embodiment of the present invention.
FIG. 9 is a plan view of FIG. 11b, and FIG. 9 is a cross-sectional line IX-IX of FIG.
FIG. 10 is a cross-sectional view of the heat sink 12 as viewed from
FIG. 3 is a cross-sectional view of the heat radiating plate 12 viewed from −X. This embodiment is similar to the previous embodiment, and corresponding parts are denoted by the same reference numerals. When the head substrate 13 is bonded to the heat radiating plate 12 as described in the above embodiment, the positioning portions 12a and 12b realize positioning. Therefore, the remaining surrounding ridges 28 are not formed in this embodiment. Even with such a configuration, the effects described in the above embodiments can be achieved in this embodiment.

Further, the formation positions of the stoppers 12a and 12b for positioning the heat sink 12 with the head substrate 13 are not limited to those in the above-described embodiment, and the stoppers 12b are replaced with the arrangement positions shown in FIG. As shown in the thermal head 11c of FIG. 11, the head substrate 13 may be formed at a position where the end of the head substrate 13 on the side to which the external wiring board 22 is connected is positioned. The stop portion 12a shown in FIG. 1 may be provided on the right side of the heat sink 12 in FIG. 1, for example, in a range shown by a two-dot chain line in FIG. Even with such a configuration, an effect similar to the effect described in the above embodiment can be achieved.

[Effects of the Invention] In the thermal head of the present invention, the side end surface of the substrate on which the heating resistor is disposed close to the protrusion is formed at a distance from the ridge formed on the heat radiating member. When assembling the thermal head by bonding on the heat radiating member, even if the adhesive slightly protrudes from between the lower surface of the substrate and the upper surface of the heat radiating member, it is formed between the side end surface of the substrate and the ridge portion. It can be accommodated in the gap, and the occurrence of poor appearance can be effectively prevented.

According to the thermal head of the present invention, it is also possible to confirm the bonding state between the substrate and the heat radiating member by observing the adhesive that has protruded into the gap between the side end surface of the substrate and the ridge. . In other words, between the substrate of the thermal head and the heat dissipating member, in particular, if there is a portion where no adhesive is present in a region directly below the heating resistor, when printing is performed, the heat storage state of the substrate becomes uneven. This may cause density unevenness in printing, but if a gap is provided between the side end surface of the substrate and the ridge as in the present invention, when assembling the thermal head by bonding the substrate to the heat dissipation member, By visually observing whether or not the adhesive has uniformly protruded into the gap, the state of adhesion between the substrate and the heat radiating member can be easily inspected.

Further, in this case, since large dust does not adhere to the adhesive in the above-described gap, the recording medium can be run stably, and the print quality can be maintained satisfactorily.

[Brief description of the drawings]

FIG. 1 is a plan view of a thermal head 11 according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line II-II of FIG.
3 is a sectional view taken along the line III-III of FIG. 1, FIG. 4 is a simplified sectional view of FIG. 2, FIG. 5 is a simplified sectional view of FIG. FIG. 7 is an enlarged sectional view of the vicinity of the concave groove 29, FIG. 7 is a sectional view of a thermal head 11a of another embodiment of the present invention, FIG. 8 is a plan view of a thermal head 11b of still another embodiment of the present invention, 9 is a sectional view taken along the section line IX-IX of FIG. 8, FIG. 10 is a sectional view taken along the section line XX of FIG. 8, and FIG. 11 is another embodiment of the present invention. FIG. 12 is a cross-sectional view of a thermal head 11c of the embodiment, FIG. 12 is a plan view of a typical conventional thermal head 1, and FIG.
FIG. 14 is a sectional view taken along XIII, and FIG. 14 is a cross-sectional line XIV-X of FIG.
FIG. 15 is an enlarged sectional view of a base end of the stopper 8a as viewed from the IV. 11,11a, 11b, 11c thermal head, 12 heat sink, 12
a, 12b: Stop portion, 13: Head substrate, 19: Heating resistor row, 27: Adhesive layer, 28: Encircling ridge, 29: Groove

Claims (1)

(57) [Scope of request for utility model registration] 1. An electrically insulating substrate having a plurality of heating resistors arranged on one main surface adjacent to a side end surface is spaced from a ridge portion formed on the side end surface of the substrate as a heat radiating member. A thermal head, wherein at least one of the side end surfaces other than the side end surface is in contact with a stop formed on the heat radiating member and is positioned and fixed on the heat radiating member.