JP4051239B2 - Thermal head and thermal printer using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermal head incorporated as a printer mechanism such as a facsimile or a video printer, and a thermal printer using the thermal head.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a thermal head has been known as one incorporated as a printer mechanism such as a facsimile or a video printer.
[0003]
As such a conventional thermal head, for example, as shown in FIGS. 8 and 9, an alumina ceramic head substrate 21 having a large number of heating resistors 23, a plurality of circuit conductors 24, a driver IC 25, and the like on the upper surface, and the above-mentioned on the upper surface. A wiring board 27 made of glass epoxy resin having a plurality of wiring conductors 28 electrically connected to the circuit conductors 24 through the fine metal wires 29 is provided side by side, and the fine metal wires 29 are shared by the strip-shaped resin material 30. A sealed structure is known. While a recording medium such as a thermal recording paper is conveyed onto the heating resistor 23 by a conveying means such as a platen roller, a number of the heating resistors 23 are driven along with driving of the driver IC 25. A specific image is formed on the thermal recording paper by selectively generating Joule heat individually and transferring the heat to the recording medium. That.
[0004]
The belt-shaped resin material 30 is formed of a relatively hard resin material such as an epoxy resin, and a liquid epoxy resin precursor is used as a boundary between the head substrate 21 and the wiring substrate 27 using a dispenser or the like. It was formed by applying to the part and heating and polymerizing it at a high temperature.
[0005]
[Problems to be solved by the invention]
By the way, in the conventional thermal head described above, the alumina ceramic constituting the head substrate 21 and the glass epoxy resin constituting the wiring substrate 27 have different linear expansion coefficients. When the precursor is heated and polymerized, a large thermal stress may be applied to the head substrate 21 or the wiring substrate 27.
[0006]
However, since the entire resin material of the above-described conventional thermal head is formed of a relatively hard epoxy resin or the like, the thermal stress generated in the head substrate 21 and the wiring substrate 27 is not so much absorbed by the resin material 30 and the thermal head. Is bent in an arcuate shape, and the linearity of the arrangement of the heating resistors 23 is lost. As a result, the image formed on the recording paper has a drawback that distortion occurs.
[0007]
Therefore, in order to eliminate the above-described drawbacks, the entire resin material is formed of a relatively soft resin material such as a silicone resin, and the thermal stress caused by the difference in coefficient of linear expansion between the head substrate 21 and the wiring substrate 27 is caused by the resin material 30. It has been proposed to absorb and prevent bending of the thermal head.
[0008]
However, when a soft resin material such as a silicone resin is used as the resin material 30, since the adhesive strength between the head substrate 21 and the wiring substrate 27 is not so high, the recording medium is placed on the surface of the resin material 30 during the recording operation. When the sliding contact is made, the positional relationship between the head substrate 21 and the wiring substrate 27 is slightly shifted due to the frictional force or the pressing force, causing the positional deviation of the heating resistor 23 and still causing the defect that the image is distorted.
[0009]
The present invention has been devised in view of the above drawbacks, and an object thereof is to provide a thermal head capable of recording a clear image with little distortion and a thermal printer using the thermal head.
[0010]
[Means for Solving the Problems]
Thermal head according to the present invention, the wiring board having a head substrate having a large number of heat-generating resistor and a plurality of circuit conductors, a plurality of wiring conductors to be electrically connected to the circuit conductor through a metal thin wire When the strip-shaped resin material for sealing the deposited was and the thin metal wire to the head substrate and the wiring board, in which Ru wherein the strip-shaped resin material, distribution only in its longitudinal central region The hard resin portion and the soft resin portion disposed only at both end regions in the longitudinal direction are located at the boundary between the head substrate and the wiring substrate. The soft resin portion is formed of a resin material softer than the resin material forming the hard resin portion . In the thermal head, the soft resin portion is preferably formed of a resin material having a Shore hardness A of 20 to 60. In the thermal head, the resin material forming the hard resin portion is preferably an epoxy resin. In this thermal head, the resin material forming the soft resin portion is preferably a silicone resin. In the thermal head, the band-shaped resin material is mainly present on the upper surface of the head substrate and the upper surface of the wiring substrate, and a part of the resin material is disposed between the head substrate and the wiring substrate. It is preferable to extend to the lower surface and the lower surface of the wiring board.
[0011]
The thermal head further includes a frame made of a resin material harder than the resin material constituting the soft resin portion and arranged along the outer periphery of the resin material so that the width in the main scanning direction is 1 mm or less. It is preferable.
[0012]
In the present thermal head , the frame body is preferably formed of the same material as the hard resin portion.
[0013]
The height of the frame in the thermal head, preferably set higher than the upper surface of the soft resin portion.
[0014]
Thermal printer according to the present invention is to a thermal head according to the present invention, a conveying means for conveying the recording medium on said thermal head, in that it comprises the features.
[0015]
According to the present invention, a head substrate having a large number of heating resistors and a plurality of circuit conductors on the upper surface, and a wiring substrate having a plurality of wiring conductors electrically connected to the circuit conductors and metal wires on the upper surface; In the thermal head formed by sealing the thin metal wires with a strip-shaped resin material in common, the strip-shaped resin material is disposed in the longitudinal central region and disposed in both longitudinal end regions. Because it is formed with the soft resin portion to be absorbed, the thermal stress due to the difference in coefficient of linear expansion between the head substrate and the wiring substrate is appropriately absorbed by the soft resin portion disposed in the longitudinal direction both end regions of the resin material, In addition to being able to effectively prevent the thermal head from curving in a bow shape, the head substrate and the wiring substrate are firmly bonded by the hard resin part arranged in the central area in the longitudinal direction, and the positional relationship between the two substrates From the initial state. It can be. Therefore, a high quality thermal head and thermal printer capable of recording a clear image with little distortion are realized.
[0016]
According to the invention, the frame made of a resin material harder than the soft resin portion of the resin material is disposed along the outer periphery of the resin material, and the soft resin is formed by the frame and the hard resin portion. By enclosing the part in a plan view, even when the resin material is formed, the soft resin material with high fluidity that forms the soft resin part will spread around it, so that it can be well dammed by the frame and the hard resin part. Therefore, the resin material can be easily formed in a desired region, and the productivity of the thermal head and the thermal printer can be kept high.
[0017]
Furthermore, according to the present invention, by forming the frame body from the same material as the hard resin portion, the frame body and the hard resin portion of the resin material can be simultaneously formed in the same process, thereby forming the frame body. By doing so, it is possible to effectively prevent the manufacturing process from becoming complicated.
[0018]
Furthermore, according to the present invention, by setting the height of the frame higher than the upper surface of the soft resin portion, the recording medium hardly hits the resin material during the recording operation. There is an advantage that a highly reliable thermal head and thermal printer can be obtained by effectively preventing a problem that the fine metal wire is damaged by the impact on the resin material due to the sliding contact of the medium.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a plan view of a thermal head according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line AA of the thermal head in FIG. 1. The thermal head shown in FIG. The wiring board 7 is provided together.
[0020]
The head substrate 1 has a large number of heating resistors 3 and a plurality of heating elements 3 formed on an upper surface of a base plate 2 formed in a long shape by various materials such as an insulating material such as alumina ceramics and single crystal silicon whose surface is covered with an oxide film. The circuit conductor 4, the driver IC 5, and the like are attached, and the upper surface functions as a support base material for supporting the heating resistor 3, the plurality of circuit conductors 4, the driver IC 5, and the like.
[0021]
When the head substrate 1 is made of alumina ceramic, for example, an appropriate organic solvent or solvent is added to and mixed with a ceramic material powder such as alumina, silica, or magnesia to form a slurry, which is conventionally known. A ceramic green sheet is obtained by adopting a doctor blade method or a calender roll method, and then the green sheet is punched into a predetermined rectangular shape and then fired at a high temperature (about 1600 ° C.).
[0022]
A number of heating resistors 3 provided on the upper surface of the head substrate 1 are linearly arranged along the long side of the head substrate 1 with a density of, for example, 600 dpi (dot per inch). Is formed of an electric resistance material such as TaSiO or TiSiO, when electric power is applied through the circuit conductors 4 connected to both ends of each heating resistor 3, Joule heat is generated, and printing is performed on the recording medium. It becomes a predetermined temperature required for forming, for example, a temperature of 150 ° C. to 250 ° C.
[0023]
Further, the plurality of circuit conductors 4 are made of a metal such as aluminum or copper, and function as power supply lines or signal lines for supplying power supply power, electric signals, etc. to the heating resistor 3 and the driver IC 5. One end is led out to the vicinity of the other long side of the head substrate 1 through the driver IC 5, and the lead-out portion and the wiring conductor 8 on the wiring substrate 7 are electrically connected through the thin metal wire 9.
[0024]
The heating resistor 3 and the plurality of circuit conductors 4 are coated on the upper surface of the head substrate 1 with a predetermined thickness and a predetermined pattern by employing a conventionally well-known thin film forming technique such as sputtering, photolithography technique, etching technique or the like. Wear and form.
[0025]
The plurality of driver ICs 5 mounted on the head substrate 1 are attached and arranged with a predetermined interval therebetween in a state substantially parallel to the arrangement of the heating resistors 3 described above. Has been.
[0026]
Such a driver IC 5 is for controlling on / off of energization to the heating resistor 3 based on image data from the outside, and a flip-chip IC is suitably used as the driver IC 5.
[0027]
For example, when a flip chip type driver IC 5 is used, an electronic circuit such as a shift register, a latch, and a switching transistor, input / output terminals, etc. are provided on the lower surface of the silicon wafer. Is mounted at a predetermined position.
[0028]
On the other hand, a wiring board 7 is provided on the other long side of the head substrate 1, that is, on the lead-out portion side of the circuit conductor 4.
[0029]
The wiring substrate 7 has a structure in which a plurality of wiring conductors 8 made of a metal material such as copper or aluminum are attached to a predetermined pattern on the upper surface of a base substrate 7a made of a glass cloth base epoxy resin or the like, The end surface on the head substrate 1 side is disposed close to the end surface of the head substrate 1.
[0030]
The wiring conductor 8 on the wiring substrate 7 is provided with a bonding pad on the head substrate 1 side, and the pad and the lead-out portion of the circuit conductor 4 of the head substrate 1 are bonded by a thin metal wire 9. As a result, external image data, electrical signals, power supply power, and the like are supplied to the heating resistor 3 and the driver IC 5 on the head substrate 1.
[0031]
When the base substrate 7a is made of a glass cloth base epoxy resin, the wiring board 7 is obtained by first impregnating and curing a liquid epoxy resin on a glass cloth base formed using glass yarn, and then forming the predetermined shape. A base substrate 7a is formed by cutting the substrate into a metal substrate, and a metal foil such as a copper foil is attached to one main surface of the base substrate 7a, and then processed into a predetermined pattern by a well-known photolithography technique and an etching technique. 8 is formed.
[0032]
A band-shaped resin material 10 that seals the thin metal wires 9 in common is attached to the upper surfaces of both the substrates 1 and 7 located at the boundary between the head substrate 1 and the wiring substrate 7.
[0033]
The resin material 10 protects the fine metal wires 9 well from the impact applied to the fine metal wires 9 as the recording medium slides, and fixes the head substrate 1 and the wiring substrate 7 together. 7, the belt-like resin material 10 is composed of a hard resin portion 10a disposed in the center region in the longitudinal direction and a soft resin disposed in both end regions in the longitudinal direction. It is comprised with the resin part 10b.
[0034]
The resin material 10 is a silicone in which the hard resin portion 10a is made of a relatively hard resin material such as an epoxy resin (for example, a resin material having a Shore hardness D of 75 to 98), and the soft resin portion 10b is softer than the hard resin portion 10a. Each of them is formed of a resin material such as a resin (for example, a resin material having a Shore hardness A of 20 to 60), and the head substrate 1 and the wiring substrate 7 are firmly bonded to each other by the hard resin portion 10a in the central region in the longitudinal direction. The thermal resin applied to the head substrate 1 and the wiring substrate 7 is absorbed and relaxed by the soft resin portions 10b at both end regions.
[0035]
For this reason, in forming the resin material 10, when the epoxy resin or silicone resin precursor is heated and polymerized, heat generated due to the difference in linear expansion coefficient between the head substrate 1 and the wiring substrate 7. Even when stress is generated, the soft resin portion 10b disposed at both end regions in the longitudinal direction of the resin material 10 is appropriately deformed to absorb and relax the thermal stress, and the thermal head is curved in an arcuate shape. In addition to being able to effectively prevent, the head substrate 1 and the wiring substrate 7 are firmly bonded by the hard resin portion 10a disposed in the central region in the longitudinal direction, so that the positional relationship between the two substrates is substantially less than the initial state. Can be held constant. Therefore, a high quality thermal head and thermal printer capable of recording a clear image with little distortion are realized.
[0036]
Here, the strip-shaped resin material 10 is formed in the central region in the longitudinal direction of the resin material 10 so that the hard resin portion 10a is disposed in the central region in the longitudinal direction and the soft resin portion 10b is disposed in both end regions. When the hard resin portion is disposed at both end regions of the soft resin portion, both ends of the boundary portion between the head substrate 1 and the wiring substrate 7 are firmly fixed, so that thermal stress is concentrated in the central region of the boundary portion. This makes it easier for the thermal printer to bend greatly in the central area. Therefore, it is important to form the belt-shaped resin material 10 so that the hard resin portion 10a is disposed in the center region in the longitudinal direction and the soft resin portions 10b are disposed in both end regions.
[0037]
The strip-shaped resin material 10 is prepared by applying a liquid epoxy resin precursor and a silicone resin precursor to a predetermined region on the head substrate upper surface and the wiring substrate upper surface using a dispenser or the like, for example, at 50 ° C. It is formed so as to straddle both substrates 1 and 7 by heating and polymerization at a temperature of ˜200 ° C.
[0038]
Next, a thermal printer using the above-described thermal head will be described with reference to FIG. FIG. 3 is a schematic diagram of a thermal printer configured using the above-described thermal printer. The thermal printer shown in FIG. 3 is a transport unit comprising the above-described thermal head Th, a platen roller 11 and a transport roller 12 in a housing. It consists of Tr.
[0039]
The platen roller 11 is configured by winding an elastic material such as silicone rubber or butadiene rubber in a roll shape around the surface of a cylindrical shaft formed of SUS or the like, and rotates to a predetermined position on the thermal head Th. The rotation is controlled by a motor or the like (not shown).
[0040]
Such a platen roller 11 presses the recording medium against the heating resistor 3 on the thermal head on the surface thereof during the recording operation to give an appropriate printing pressure to the recording medium, and the recording medium is heated to the heating resistor 3. For traveling at a predetermined speed in a direction perpendicular to the arrangement.
[0041]
Similarly to the platen roller 11 described above, the transport roller 12 has a structure in which an elastic material made of silicone rubber is wound around a shaft made of SUS, and is upstream of the thermal head Th in the transport direction of the recording medium. And is arranged in a rotatable state on the downstream side.
[0042]
Similar to the platen roller 11, the conveyance roller 12 is controlled to rotate by a motor (not shown) and the like, and has a function of stably feeding the recording medium onto the heating resistor 3.
[0043]
Thus, the thermal printer described above individually transfers the heating resistor 3 based on image data from the outside while conveying a recording medium such as thermal recording paper onto the heating resistor 3 using the conveying roller 12 and the platen roller 11. While selectively generating Joule heat, the generated heat is transmitted to a recording medium, and a predetermined image is recorded on the recording medium, thereby functioning as a thermal printer.
[0044]
The present invention is not limited to the above-described embodiment, and various modifications and improvements can be made without departing from the scope of the present invention.
[0045]
For example, in the above-described embodiment, as shown in FIGS. 4 and 5, the frame body 13 made of a resin material harder than the soft resin portion 10 b of the resin material 10 is disposed along the outer periphery of the belt-shaped resin material 10. In addition, if the soft resin portion 10b of the resin material 10 is surrounded by the frame 13 and the hard resin portion 10b of the resin material 10 in a plan view, the soft resin portion 10b of the resin material 10 is formed. At this time, even if the soft resin material having high fluidity spreads to the surroundings, the resin material 10 is desired to be satisfactorily dammed by the previously formed frame body 10 and hard resin portion 10a. It can be easily formed in the region, and the productivity of the thermal head and the thermal printer can be kept high. In this case, since the frame bodies 10 disposed at both ends in the longitudinal direction of the resin material 10 are very thin (the width W in the main scanning direction is 1 mm or less), the thermal head is formed by the frame body 10. The problem of being easily bent is effectively prevented.
[0046]
At this time, if the frame body 13 is formed of the same material as the hard resin portion 10a of the resin material 10, the frame body 13 and the hard resin portion 10a of the resin material 10 are collectively formed in the same process. It is possible to effectively prevent the manufacturing process of the thermal head and the thermal printer from becoming complicated.
[0047]
Further, if the height of the frame 13 is set higher than the upper surface of the soft resin portion 10b of the resin material 10, the recording medium hardly hits the surface of the resin material 10 during the recording operation. Therefore, it is possible to effectively prevent a problem that the fine metal wire 9 is broken by a strong impact on the resin material 10 due to the sliding contact of the recording medium, and there is an advantage that a reliable thermal head and thermal printer can be obtained.
[0048]
Further, as shown in FIG. 6, if the driver IC 5 is covered by extending a part of the frame 13 to the driver IC 5 side, a protective film and a frame for covering the driver IC 5 are formed separately. This makes it unnecessary to simplify the manufacturing process of the thermal head and the thermal printer.
[0049]
Furthermore, in the above-described embodiment, the lower region of the resin material is extended to the lower surface of the head substrate 1 and the lower surface of the wiring substrate 7 through a gap formed between the head substrate 1 and the wiring substrate 7. If the head substrate 1 and the wiring substrate 7 are fixed with a resin material including the extending portion, there is an advantage that the substrates 1 and 7 can be bonded more firmly.
[0050]
【The invention's effect】
According to the present invention, a head substrate having a large number of heating resistors and a plurality of circuit conductors on the upper surface, and a wiring substrate having a plurality of wiring conductors electrically connected to the circuit conductors and metal wires on the upper surface; In the thermal head formed by sealing the thin metal wires with a strip-shaped resin material in common, the strip-shaped resin material is disposed in the longitudinal central region and disposed in both longitudinal end regions. Because it is formed with the soft resin portion to be absorbed, the thermal stress due to the difference in coefficient of linear expansion between the head substrate and the wiring substrate is appropriately absorbed by the soft resin portion disposed in the longitudinal direction both end regions of the resin material, In addition to being able to effectively prevent the thermal head from curving in a bow shape, the head substrate and the wiring substrate are firmly bonded by the hard resin part arranged in the central area in the longitudinal direction, and the positional relationship between the two substrates From the initial state. It can be. Therefore, a high quality thermal head and thermal printer capable of recording a clear image with little distortion are realized.
[0051]
According to the invention, the frame made of a resin material harder than the soft resin portion of the resin material is disposed along the outer periphery of the resin material, and the soft resin is formed by the frame and the hard resin portion. By enclosing the part in a plan view, even when the resin material is formed, the soft resin material with high fluidity that forms the soft resin part will spread around it, so that it can be well dammed by the frame and the hard resin part. Therefore, the resin material can be easily formed in a desired region, and the productivity of the thermal head and the thermal printer can be kept high.
[0052]
Furthermore, according to the present invention, by forming the frame body from the same material as the hard resin portion, the frame body and the hard resin portion of the resin material can be simultaneously formed in the same process, thereby forming the frame body. By doing so, it is possible to effectively prevent the manufacturing process from becoming complicated.
[0053]
Furthermore, according to the present invention, by setting the height of the frame higher than the upper surface of the soft resin portion, the recording medium hardly hits the resin material during the recording operation. There is an advantage that a highly reliable thermal head and thermal printer can be obtained by effectively preventing a problem that the fine metal wire is damaged by the impact on the resin material due to the sliding contact of the medium.
[Brief description of the drawings]
FIG. 1 is a plan view of a thermal head according to an embodiment of the present invention.
2 is a cross-sectional view of the thermal head of FIG. 1 taken along line AA.
FIG. 3 is a schematic diagram of a thermal printer configured by incorporating the thermal head of FIG. 1;
FIG. 4 is a plan view of a thermal head according to another embodiment of the present invention.
5 is a cross-sectional view taken along line AA of the thermal head in FIG. 4. FIG.
FIG. 6 is a plan view of a thermal head according to another embodiment of the present invention.
7 is a cross-sectional view of the thermal head of FIG. 6 along the line AA.
FIG. 8 is a plan view of a conventional thermal head.
9 is a cross-sectional view of the thermal head of FIG. 8 taken along the line AA.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Head substrate 2 ... Base plate 3 ... Heating resistor 4 ... Circuit conductor 5 ... Driver IC
7 ... Wiring board 7a ... Base board 8 ... Wiring conductor 9 ... Metal wire 10 ... Resin material 10a ... Hard resin part 10b ... Soft resin part 11 ... Platen roller 12 ... Conveying roller 13 ... Frame Th ... Thermal head Tr ... Conveying means

Claims (9)

A head substrate having a heating resistor and a plurality of circuit conductors of a multi-speed, a wiring board having a plurality of wiring conductors to be electrically connected to the circuit conductor through a metal thin wire, the head substrate and the wiring and the resin material of the strip for sealing the deposited was and the thin metal wire to the substrate, the thermal head Ru provided with,
The belt-shaped resin material is composed of a hard resin portion disposed only in a central region in the longitudinal direction and a soft resin portion disposed only in both longitudinal end regions , and between the head substrate and the wiring substrate. Located at the border,
The hard resin portion is formed of a resin material 75 to 98 in Shore hardness D, the soft resin portion is characterized in that it is formed by soft resin material a resin material for forming the hard resin portion, thermal head. 2. The thermal head according to claim 1, wherein the soft resin portion is formed of a resin material having a Shore hardness A of 20 to 60. 3. The thermal head according to claim 1, wherein the resin material forming the hard resin portion is an epoxy resin. 4. The thermal head according to claim 1, wherein the resin material forming the soft resin portion is a silicone resin. The band-shaped resin material is mainly present on the upper surface of the head substrate and the upper surface of the wiring substrate, and a part of the strip-shaped resin material is interposed between the head substrate and the wiring substrate and the lower surface of the head substrate and the wiring The thermal head according to claim 1, wherein the thermal head extends on a lower surface of the substrate. It further comprises a frame body made of a resin material harder than the resin material constituting the soft resin portion and arranged along the outer periphery of the resin material so that the width in the main scanning direction is 1 mm or less. The thermal head according to any one of claims 1 to 5. The thermal head according to claim 6, wherein the frame is made of the same material as the hard resin portion. 8. The thermal head according to claim 6, wherein a height of the frame is set to be higher than an upper surface of the soft resin portion. A thermal printer comprising: the thermal head according to any one of claims 1 to 8; and a transport unit that transports a recording medium onto the thermal head.

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