JP2002192761A - Thermal head and thermal printer using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal head that can form a high quality image by effectively preventing a wrinkle or a flaw from being created on a recording medium. SOLUTION: A head substrate 1 wherein a plurality of heating resistors 4 are arranged thereon along one side of the top face in a roughly quadrangular shape is provided on a radiator plate 7. A support member 8 having a top face which is to be connected to the top face of the head substrate 1 being flush therewith is attached to the radiator plate 7. A coefficient of dynamic friction of the top face of the support member 8 is equal to or lower than a coefficient of dynamic friction of the top face of the head substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head incorporated as a printer mechanism for a word processor, a facsimile or the like, and a thermal printer using the same.

[0002]

2. Description of the Related Art Conventionally, in a thermal head incorporated as a printer mechanism such as a word processor, for example, as shown in FIG. 4, a plurality of heating resistors 12 are attached and arranged along one side of a substantially rectangular upper surface. And a recording medium such as a thermal paper using an external platen roller 15 disposed on the heat generating resistor 12. While sequentially transporting the heating resistors 12 onto the heating resistors 12, the heating resistors 12 are individually and selectively subjected to Joule heating based on image data from the outside, and the generated heat is conducted to the recording medium, and By forming a predetermined print image, it functions as a thermal head.

The platen roller 15 is used to convey the recording medium in a predetermined direction while pressing the recording medium against the head substrate 11 of the thermal head during printing. The platen roller 15 is made of SUS or the like. A structure in which an elastic material such as silicone rubber is wound around an axis has been used.

[0004]

However, in the above-described conventional thermal head, since the heating resistor 12 is disposed near the end of the head substrate 11,
When a relatively large diameter platen roller 15 is used to secure a wide nip width (contact width between the thermal head and the recording medium) during printing, a part of the platen roller 15 protrudes outside the head substrate 11 and In some cases, there is a problem that the corners of the ellipse 11 are hard to enter the platen roller 15. In this case, the recording medium is the head substrate 1
In this case, the recording medium is bent along the corner, and the recording medium has a drawback of causing wrinkles and scratches.

The present invention has been devised in view of the above-mentioned drawbacks, and has as its object to provide a thermal head capable of effectively preventing wrinkles and scratches on a recording medium and forming a high-quality print. And a thermal printer using the same.

[0006]

According to the present invention, there is provided a thermal head in which a head substrate on which a plurality of heating resistors are attached and arranged along one side of a substantially rectangular upper surface is placed on a heat sink. At the same time, a support member having an upper surface continuously provided in substantially the same plane as the upper surface of the head substrate is attached to the heat sink, and the kinetic friction coefficient of the upper surface of the support member is further reduced by the movement of the upper surface of the head substrate. The friction coefficient is set to be equal to or less than the friction coefficient.

The thermal head according to the present invention is characterized in that the support member is movable in a direction orthogonal to the arrangement of the heating resistors.

A thermal printer according to the present invention includes the above-described thermal head, and a platen roller that conveys the recording medium from the heating resistor toward the support member while pressing the recording medium against the thermal head. A platen roller is mounted at a predetermined position on the thermal head so that the pressing force is applied to both the upper surface of the head substrate and the upper surface of the support member of the thermal head.

According to the present invention, since the supporting member having the upper surface continuously provided in substantially the same plane as the upper surface of the head substrate is attached to the heat radiating plate of the thermal head, When the platen roller is disposed on the substrate, even if a portion of the platen roller protrudes outside the head substrate, this portion is well supported by the upper surface of the support member, and the corners of the head substrate enter the platen roller. Can be effectively prevented. Therefore, the recording medium is not bent near the corners of the head substrate, and a good print with less wrinkles and scratches can be formed.

Further, according to the present invention, the kinetic friction coefficient of the upper surface of the support member is set to be equal to or less than the kinetic friction coefficient of the upper surface of the head substrate. Even if the recording medium is conveyed from the heating resistor to the support member while pressing the upper surfaces of both members, the traveling of the recording medium does not become unstable on the support member, and sticking and paper jams may occur. The occurrence can be effectively prevented, and the reliability of the thermal printer can be improved.

Further, according to the present invention, the support member can be moved in the sub-scanning direction and is attached to a heat radiating plate, so that the processing accuracy varies when the head substrate and the support member are manufactured, and when the thermal head is used. Even if a gap is generated between the head substrate and the support member due to the application of heat or vibration, the position of the support member is moved to the head substrate side so that the side surface of the support member contacts the end surface of the head substrate. Accordingly, the gap between the two can be minimized, and the above-described effect can be reliably obtained for a long period of time.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 is a perspective view of a thermal head according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the thermal head of FIG. 1, 1 is a head substrate, 4 is a heating resistor, 7 is a heat sink, and 8 is a support member. It is.

The head substrate 1 has a structure in which a glaze layer 3 and a plurality of heating resistors 4 are disposed on an insulating substrate 2 made of alumina ceramics whose upper surface is formed in a substantially square shape. are doing.

The insulating substrate 2 functions as a supporting base material for supporting the glaze layer 3, the heating resistor 4, and the like, and a ceramic green sheet formed using a ceramic material such as alumina, silica, magnesia, etc. It is manufactured by punching into a shape and firing at a high temperature.

The glaze layer 3 provided on the upper surface of the insulating substrate 2 is attached in a strip shape along one side of the insulating substrate 2, and a plurality of heating resistors 4 are provided near the top.
Is provided.

The glaze layer 3 is made of a low thermal conductive material such as glass or polyimide resin, and stores a part of the heat generated by the heat generating resistor 4 therein, thereby maintaining good thermal response characteristics of the thermal head. To act.

When the glaze layer 3 is made of glass, a predetermined glass paste obtained by adding and mixing an appropriate organic solvent to glass powder is strip-shaped along one side of the upper surface of the head substrate by a conventionally known screen printing or the like. Is formed by printing and coating on the substrate and baking it at a high temperature.

On the other hand, the plurality of heat generating resistors 4 provided on the glaze layer 3 are, for example, 600 dpi (dots).
(per inch) at a density in the main scanning direction, each of which is formed of an electric resistance material such as TaSiO, TiSiO, TaN, etc. When power is applied via the power supply 5 or the like, Joule heat is generated, and the temperature reaches a predetermined temperature required for forming an image on a recording medium such as thermal paper.

The heating resistor 4 is adhered and formed in a predetermined thickness and a predetermined pattern by employing a conventionally known thin film forming technique, specifically, a sputtering, a photolithography technique, an etching technique or the like. Note that these heating resistors 4 are located at a position separated from the one side of the insulating substrate 2 by, for example, 0.5 mm to 5.0 mm.
Is disposed in the vicinity of the edge (edge).

Further, a protective film 6 is provided on the upper surface of the insulating substrate 2 on which the glaze layer 3 and the heating resistor 4 are provided so as to cover them.

The protective film 6 is formed of an inorganic material such as silicon nitride or sialon and has a thickness of, for example, 4 μm to 10 μm. The protective film 6 is formed by contacting the heating resistor 4 and the like with moisture contained in the atmosphere. It functions to protect against corrosion and wear due to sliding contact of the recording medium.

Such a protective film 6 employs conventionally known sputtering or the like, and is made of the above-mentioned inorganic material by using the heating resistor 4.
And a predetermined thickness on the upper surface of the glaze layer 3, the insulating substrate 2, and the like.

The surface roughness of the upper surface of the head substrate covered with the protective film 6 is from 0.03 μm to arithmetic mean roughness Ra.
The kinetic friction coefficient (sliding friction) is set to 0.3 to 0.4.

The above-described head substrate 1 is provided with a heat radiating plate 7.
Placed and fixed on top. The heat radiating plate 7 is formed of a metal such as aluminum or SUS. The heat radiating plate 7 supports the head substrate 1 on its upper surface, absorbs a part of the heat of the head substrate 1, and dissipates it in the atmosphere. This effectively prevents the temperature of the head substrate 1 from becoming excessively high. In addition, a concave portion 7a for inserting one end of a support member 8 described later is provided on a side surface of the heat radiating plate 7.

When the heat radiating plate 7 is made of aluminum, the heat radiating plate 7 is manufactured by processing an aluminum ingot (lumps) into a predetermined shape by using a conventionally known metal working method. The head substrate 1 is fixed at a predetermined position on the heat radiating plate 7 by adhering an adhesive such as a tape and mounting and positioning the above-described head substrate 1 thereon. At this time, the position of the head substrate 1 is set so that the end surface along one side of the head substrate 1 on which the heating resistor 4 is provided projects slightly outside the end surface of the heat sink 7.

The heat sink 7 has a head substrate 1
A support member 8 having an upper surface continuously provided in substantially the same plane as the upper surface is attached.

The support member 8 is made of aluminum or SUS.
And a resin such as ABS (acrylonitrile / butadiene / styrene) or PBT (polybutylene / terephthalate), and is formed to have an L-shaped cross section. The heat sink 7 and the support member 8 are inserted into the heat sink 7 at the insertion portion.
The support member 8 is attached to the heat radiating plate 7 by screwing (screw: 9) from the lower surface side.

The side surface of the support member 8 on the side of the head substrate 1 is in contact with the end surface of the head substrate 1, and there is almost no gap between the support member 8 and the end surface of the head substrate 1. When the platen roller 10 is disposed thereon, even if a portion of the platen roller 10 protrudes outside the head substrate 1, this portion is favorably supported by the upper surface of the support member 8, and It is possible to effectively prevent the corners from getting into the platen roller 10. Therefore, the recording medium does not bend near the corners of the head substrate 1, and a good print with less wrinkles and scratches can be formed.

The support member 8 is provided on the platen roller 1.
The kinetic friction coefficient of the upper surface supporting 0 is set equal to (within ± 0.1) or less than the kinetic friction coefficient of the head substrate upper surface.

On the upper surface of the support member 8, a coating (not shown) made of, for example, a fluororesin is used.
The kinetic friction coefficient (sliding friction) on the upper surface of the support member is set to a value (0.1 to 0.5) equal to or smaller than the kinetic friction coefficient on the upper surface of the head substrate. I have.

Therefore, during the printing operation, the platen roller 10
When the recording medium is conveyed from the heating resistor 4 to the supporting member 8 while pressing the upper surfaces of both the head substrate 1 and the supporting member 8 with the, the running of the recording medium is unstable on the supporting member 8. However, the occurrence of sticking and paper jam can be effectively prevented, and the reliability of the thermal printer in which the thermal head is incorporated can be improved.

Further, if the supporting member 8 is attached to the heat radiating plate 7 so as to be movable in a direction (sub-scanning direction) orthogonal to the arrangement of the heating resistors 4, the head substrate 1 and the supporting member 8 are manufactured. Even if there is a gap between the head substrate 1 and the support member 8 due to variations in processing accuracy at the time or the application of heat or vibration during use of the thermal head, once the screw 9 is loosened, By correcting the position, the side surface of the supporting member 8 can be satisfactorily brought into close contact with the end surface of the head substrate 1, and the gap can be minimized between the two members 1, 8, and the above-described effect can be reliably obtained for a long time. It is also possible. In order to enable such movement, for example, a large play (play amount: 1 mm to 2 mm) in the sub-scanning direction may be provided in a screw hole of the heat sink 7 to which the support member 8 is screwed. The support member 8 can be moved in the sub-scanning direction within the range of.

Further, if the support member 8 is formed of a metal such as aluminum or SUS, the support member 8 is brought into contact with the end face of the head substrate 1 so that
Since the heat in the head substrate 1 can be absorbed by the supporting member 8 through the end surface thereof, even if the heating resistor 4 is repeatedly subjected to Joule heat in a short time in performing high-speed printing, the heat in the head substrate 1 is reduced. A part is quickly radiated to the outside not only through the heat radiating plate 7 but also through the supporting member 8, so that the temperature of the head substrate 1 is maintained at a favorable temperature suitable for printing, and clear printing with less density unevenness is achieved. Can also be formed.

When the support member 8 is made of, for example, aluminum, an aluminum ingot is formed into an L-shape by using a conventionally known metal working method, and a fluororesin is formed on the upper surface thereof by a conventionally known dip method. One end of the obtained support member 8 is inserted into the concave portion 6a of the radiator plate 7 as described above, and the radiator plate 7 and the support member 8 are screwed at the inserted portion. Thus, it is attached to the heat sink 7.

When a thermal printer is constructed using the above-described thermal head, a platen roller 10 is mounted on the heating resistor 4 of the head substrate 1.

The platen roller 10 has a structure in which an elastic material such as silicone rubber is wound around an axis made of SUS or the like, and is rotatably supported at a predetermined position on a thermal head. Its rotation is controlled.

During the printing operation, the platen roller 10 presses the recording medium against the heating resistor 4 on the head substrate 1 to apply an appropriate printing pressure to the recording medium and to align the recording medium with the arrangement of the heating resistor 4. This is for running at a predetermined speed in a direction (sub-scanning direction) orthogonal to the recording medium. To secure a wide nip width necessary for bringing the recording medium into good contact with the thermal head, a diameter of 30 mm to 80 mm is required. A relatively large platen roller 7 is used.

In this case, since the pressing force from the platen roller 10 is applied to both the upper surface of the head substrate 1 and the upper surface of the support member 8, the corners of the head substrate 1 do not enter the platen roller 10 as described above. However, it is possible to effectively prevent wrinkles and scratches from being generated on the recording medium.

Thus, in the above-described thermal printer, a plurality of heating resistors 4 of the thermal head are individually selectively selected based on image data while a recording medium such as thermal paper is fed between the platen roller 10 and the thermal head. Joule heat is generated, and the generated heat is conducted to the recording medium to form a predetermined print on the recording medium, thereby functioning as a thermal head.

It should be noted that the present invention is not limited to the above-described embodiment, and various changes and improvements can be made without departing from the gist of the present invention.

For example, in the above-described embodiment, the fluororesin is applied so that the kinetic friction coefficient of the upper surface of the support member is equal to or less than that of the upper surface of the head substrate. A coefficient of kinetic friction may be realized. For example, when the support member 8 is made of aluminum, a thin film of aluminum oxide having a predetermined coefficient of kinetic friction may be formed by performing an alumite treatment on the upper surface, The predetermined coefficient of kinetic friction may be realized only by mirror finishing without forming any coating on the upper surface of the support member 8.

In the above-described embodiment, the support member 8 is provided with a screw hole having a large play so that the support member 8 can be attached to the heat radiating plate 7 so as to be movable. Alternatively, the support member 8 may be fixed using a push rivet or the like.

Further, in the above-described embodiment, the entire upper surface of the support member 8 is formed substantially flat. Instead, as shown in FIG. As shown in FIG. 3B, the side of the support member 8 ″ located on the opposite side to the head substrate 1 is processed into a fin shape as the distance from the head substrate 1 increases. As shown in FIGS. 3A and 3B, a spot facing for accommodating the head of the screw 8 may be provided near the opening of the screw hole.

Further, in the above-described embodiment, a double-sided tape is used as an adhesive for fixing the head substrate 1 to the heat radiating plate 7, but the head substrate 1 is fixed to the heat radiating plate 7 using an adhesive other than the double-sided tape. It may be fixed to.

[0045]

According to the present invention, since the heat radiating plate of the thermal head is provided with the support member having the upper surface continuously provided in substantially the same plane as the upper surface of the head substrate,
When the platen roller is arranged on the head substrate of the thermal head, even if a part of the platen roller protrudes outside the head substrate, this part is well supported by the upper surface of the support member, and the corners of the head substrate It is possible to effectively prevent the platen roller from being jammed. Therefore, the recording medium is not bent near the corners of the head substrate, and a good print with less wrinkles and scratches can be formed.

Further, according to the present invention, the kinetic friction coefficient of the upper surface of the support member is set to be equal to or less than the kinetic friction coefficient of the upper surface of the head substrate. Even if the recording medium is conveyed from the heating resistor to the support member while pressing the upper surfaces of both members, the traveling of the recording medium does not become unstable on the support member, and sticking and paper jams may occur. The occurrence can be effectively prevented, and the reliability of the thermal printer can be improved.

Further, according to the present invention, the support member can be moved in a direction perpendicular to the arrangement of the heating resistors and is attached to the heat radiating plate, so that the processing accuracy in manufacturing the head substrate and the support member varies. Even if a gap is created between the head substrate and the support member due to the application of heat or vibration during use of the thermal head or the thermal head, the position of the support member is moved to the head substrate side and the side surface of the support member is moved to the head substrate. By making contact with the end faces, the gap between the two can be minimized, and the above-mentioned effects can be reliably obtained for a long period of time.

[Brief description of the drawings]

FIG. 1 is a perspective view of a thermal head according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the thermal head of FIG.

FIGS. 3A and 3B are cross-sectional views of a thermal head according to another embodiment of the present invention.

FIG. 4 is a sectional view of a conventional thermal head.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Head board, 4 ... Heating resistor, 7 ... Heat sink, 8, 8 ', 8 "... Support member, 10 ... Platen roller

Claims (3)

[Claims] 1. A head substrate on which a plurality of heating resistors are attached and arranged along one side of an upper surface having a substantially rectangular shape is mounted on a heat sink, and the head substrate is mounted on the heat sink. A support member having an upper surface continuously provided in substantially the same plane as the upper surface of the head substrate is attached, and the kinetic friction coefficient of the upper surface of the support member is set to be equal to or less than the kinetic friction coefficient of the upper surface of the head substrate. A thermal head characterized by the following. 2. The thermal head according to claim 1, wherein the support member is movable in a direction orthogonal to the arrangement of the heating resistors. 3. A platen comprising: a thermal head according to claim 1; and a platen roller configured to convey a recording medium from a heating resistor toward a support member while pressing the recording medium against the thermal head. A thermal printer comprising a platen roller mounted at a predetermined position on a thermal head so that a pressing force from a roller is applied to both the upper surface of a head substrate and the upper surface of a support member of the thermal head.