JP2016150472A - Thermal head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal head which has stable printing quality.SOLUTION: A heating element plate 20 includes: an insulation plate 22a placed on the upper surface of a radiator plate 30 while being adjacent to the circuit board 40 in a sub-scanning direction ds; a glass layer 22b formed on the upper surface of the insulation plate 22a; a plurality of heating resistors 23a formed on the upper surface of the glass layer 22b, arrayed at intervals in a main scanning direction dm, and driven by a driving IC 42 mounted on the circuit board 40; an electrode layer 28 facing the surface of the heating resistors 23a with a gap on the surface of the heating resistor 23a; a protection layer 29 formed on the upper surface of the glass layer 22b as a heat insulation layer; and a bonding wire 44 connecting the electrode layer 28 with the driving IC 42. Protection parts 74, which are made of resin for connecting the upper surface of the heating element plate 20 and the end face of the heating element plate 20 in the main scanning direction dm with a round-shaped curved surface gradually inflected at an angle of less than 90 degrees and not projecting from the upper surface of the heating element plate 20, are formed on both end parts in the main scanning direction dm.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a thermal head used in a thermal printer or the like.

  The thermal head generates heat on the heating portions of a plurality of heating resistors arranged in a direction (main scanning direction) orthogonal to the direction in which the printing medium such as thermal recording paper is conveyed, and the heat causes characters on the printing medium. This is an output device for forming images such as images and figures. This thermal head is widely used in recording devices such as a barcode printer, a digital plate making machine, a video printer, an imager, and a seal printer.

  A general thermal head includes a heat radiating plate, a heat generating plate attached to the heat radiating plate, and a circuit board attached to the heat radiating plate on the same side as the heat generating plate. Heat generating resistors are linearly arranged at predetermined intervals in a heat generating region extending in a band shape on the surface opposite to the surface of the heat generating plate opposite to the heat radiating plate. Also, a drive IC (Integrated Circuit) that is a part of a drive circuit that drives the heating resistor is mounted on, for example, a circuit board (see, for example, Patent Document 1).

JP 2012-66476 A

  In such a thermal head, when printing on a printing medium such as a film, corner portions formed at the junction between the upper surface and the side surface at both ends in the main scanning direction dm of the heating element plate 120 shown in FIG. There is a possibility that the printing medium is rubbed and a streak-like scratch is formed on the printing medium and the print quality is deteriorated.

  Accordingly, an object of the present invention is to maintain the print quality of a thermal head.

  In order to solve the above-described problems, an embodiment of the present invention includes a heat sink, a circuit board mounted on the upper surface of the heat sink and mounting a driving IC, and mounted on the upper surface of the heat sink adjacent to the circuit board. A heating head, and the heating plate is an insulating substrate placed on the upper surface of the heat sink adjacent to the circuit board, and a heat insulating plate formed on the upper surface of the insulating substrate. And a plurality of heating resistors formed on the upper surface of the heat insulating layer and arranged in the main scanning direction at intervals, and a surface of the heating resistor is sandwiched between the heating resistor driven by the driving IC and the surface of the heating resistor Electrode layers facing each other, a protective layer formed on the upper surface of the heat insulating layer, and a bonding wire connecting the electrode layer and the driving IC, and at both ends in the main scanning direction, The end face of the heating element plate in the main scanning direction protrudes from the upper surface of the heating element plate And a protective portion is formed of a resin to be connected with no curved surface.

  According to the present invention, the print quality of the thermal head can be maintained.

1 is a cross-sectional view of a part of a thermal printer using an embodiment of a thermal head according to the present invention. 1 is a partial front view of a thermal printer using an embodiment of a thermal head according to the present invention. It is a perspective view in one embodiment of a thermal head concerning the present invention. It is a partially cutaway top view in an embodiment of a thermal head according to the present invention. It is a perspective view in one embodiment of a heating element board concerning the present invention. It is a flowchart of the manufacturing method in one Embodiment of the thermal head which concerns on this invention. It is a perspective view after protective layer formation in the manufacturing method of the thermal head concerning the present invention. It is a perspective view after the grooving process in the manufacturing method of the thermal head which concerns on this invention. It is a perspective view after division processing in the manufacturing method of the thermal head concerning the present invention. It is a perspective view at the time of resin material application | coating in the manufacturing method of the thermal head concerning this invention. It is a perspective view of the conventional heat generating body plate (1). It is a perspective view of the conventional heat generating body plate (2).

  An embodiment of a thermal head according to the present invention will be described with reference to the drawings. This embodiment is merely an example, and the present invention is not limited to this.

  1 to 12, the direction of the arrow ds represents the direction (sub-scanning direction) in which the printing medium is conveyed, and the direction orthogonal to the sub-scanning direction ds is orthogonal to the direction in which the printing medium is conveyed. A plurality of heat generating resistors 23a are arranged at intervals and the heat generating region 24 extends (main scanning direction).

  The thermal head 10 of the present embodiment includes, for example, a heating element plate 20, a circuit board 40, and a heat dissipation plate 30. The heat generating plate 20 and the circuit board 40 are placed on the same surface of the heat radiating plate 30. The heat sink 30 is a plate formed of a metal such as aluminum.

  The heat generating plate 20 is fixed to the heat radiating plate 30 with an adhesive such as a double-sided tape along one end side of the circuit board 40 in the sub-scanning direction ds. The heat generating plate 20 is formed with a heat generating region 24 extending in a strip shape. A control signal and driving power for forming a predetermined heat generation pattern in the heat generation region 24 are input to the circuit board 40 and further input to the heating element plate 20 electrically connected to the circuit board 40.

  A thermal printer using the thermal head 10 has a platen roller 50 formed in a cylindrical shape with a material having a predetermined elasticity. The platen roller 50 has a width in the main scanning direction dm that is longer than that of the printing medium 60, the thermal ribbon 63, and the heat generating plate 20, and has a shaft 52 on a straight line parallel to the main scanning direction dm. Further, the peripheral side surface of the platen roller 50 is disposed so as to be in contact with the heat generating region 24, and is provided to be rotatable about the shaft 52.

  The thermal printer has a thermal ribbon 63. The thermal ribbon 63 is formed so that the width in the main scanning direction dm is longer than that of the printing medium 60, and is wound around a shaft 65 that is parallel to the shaft 52 of the platen roller 50. The heat-sensitive ribbon 63 wound in a roll shape is wound around an axis 66 parallel to the axis 65. The winding-side shaft 66 is driven by a motor or the like. The thermal ribbon 63 is conveyed so as to pass between the side surface of the platen roller 50 and the thermal head 10. The print medium 60 is conveyed along the sub-scanning direction ds so as to pass between the thermal ribbon 63 and the platen roller 50.

  The thermal ribbon 63 is formed with a plurality of types of color areas in the winding direction. Each color region of the thermal ribbon 63 is colored when a predetermined temperature or higher is reached, and the color is transferred to the printing medium 60 that is in contact therewith.

  The thermal printer presses the thermal head 10 against the printing medium 60 such as a film via the thermal ribbon 63 by pressing the thermal head 10 in a direction pressing the platen roller 50 with a head pressing unit (not shown) constituted by a drive motor. Apply nip pressure. At the same time, the thermal printer moves the print medium 60 in the sub-scanning direction ds, and changes the heat generation pattern of the heat generation area 24 with the movement of the print medium 60, thereby forming a desired image on the print medium 60. To do.

  The heating element plate 20 is formed so that the width in the main scanning direction dm is shorter than the printing medium 60 and the thermal ribbon 63, and includes the support substrate 22, the heating resistor layer 23, the electrode layer 28, and the protective layer 29. doing.

The support substrate 22 has a ceramic insulating plate 22a such as alumina (Al ₂ O ₃ ), for example, and a glass layer 22b called a glaze layer. The insulating plate 22a is a chamfered portion that is chamfered in a planar shape from one end to the other end in the main scanning direction dm at the end on the downstream side in the transport direction of the print medium 60 and the side away from the circuit board 40. By forming 68, the printing medium 60 transported in the sub-scanning direction ds is prevented from being caught by the heating plate 20. The chamfering depth D1, which is the depth of the chamfered portion 68 orthogonal to the main surface of the insulating plate 22a, is less than 0.2 mm. The glass layer 22b is made of silicon oxide (SiO ₂ ) on the upper surface of the chamfered portion 68 of the insulating plate 22a and is formed in a layer shape with a thickness of about 25 μm.

The heating resistor layer 23 is formed in layers on a part of the upper surface of the insulating plate 22a and the glass layer 22b, for example, with a cermet such as TaSiO ₂ . In the heating resistor layer 23, the heating resistors 23a are arranged in a row continuously from one end to the other end in the main scanning direction dm of the one heating plate 20 at intervals in the main scanning direction dm. It extends in the direction ds.

  The electrode layer 28 is formed in a layer on a part of the upper surface of the heating resistor layer 23. The electrode layer 28 includes a common electrode 28b and individual electrodes 28a made of, for example, aluminum (Al).

  The common electrode 28b is formed on the upper surface of the heating resistor layer 23 so as to extend in the main scanning direction dm. The individual electrodes 28a are arranged in a row from one end to the other end in the main scanning direction dm of the single heating element plate 20 at intervals in the main scanning direction dm, and are provided at the tops of the protrusions 21. Is disposed opposite to the common electrode 28b from the sub-scanning direction ds.

  Since the current flowing through the common electrode 28b passes through the heating resistor 23a in the gap portion located between the individual electrode 28a and the common electrode 28b, the heating resistor 23a in the gap portion functions as the heating portion 23b. To do. The heat generating portions 23 b are arranged at intervals in the main scanning direction dm, and form a heat generating region 24 that extends in the main scanning direction dm on the upper surface of the chamfered portion 68.

  One end of the bonding wire 44 is connected to the bonding pad 26 of the individual electrode 28a, and the other end is connected to the drive IC 42 on the circuit board 40, and a control signal for forming a predetermined heat generation pattern is supplied to the heat generation region 24. Is done. One end of a bonding wire 45 is connected to the drive IC 42, and the other end is connected to a circuit pattern on the circuit board 40.

  The individual electrode 28a, the common electrode 28b, and the heating resistor layer 23 are covered with a protective layer 29 made of, for example, silicon oxynitride (SiON). The protective layer 29 is not provided on a part of the surface of the individual electrode 28a, and a bonding wire 44 is connected to this part. The drive IC 42 and the bonding wire 44 are sealed with a resin 48.

  Further, the heating element plate 20 has a groove depth which is a depth which is approximately 1.5 to 2.0 mm in width in the main scanning direction dm at both ends in the main scanning direction dm and which is perpendicular to the main surface of the insulating plate 22a. A groove portion 70 having a notch with a length D2 of 0.2 mm or more is formed from one end to the other end in the sub-scanning direction ds. As shown in FIG. 9, the groove portion 70 has a wall surface 71 perpendicular to the main surface of the insulating plate 22a, and a bottom surface 72 orthogonal to the wall surface 71 and parallel to the main surface of the insulating plate 22a. The angle between the main surface of the insulating plate 22a and the end surfaces of both ends of the heat generating plate 20 in the main scanning direction dm is approximately 90 degrees. The groove depth D2 is deeper than the chamfering depth D1.

  A protective part 74 made of resin is formed in the groove part 70. The protection part 74 has a curved surface shape with a curved surface. For this reason, the upper surface of the protective layer 29 and the heating element plate main scanning direction end face 20a, which is the end face of the heating element plate 20 in the main scanning direction dm, are continuous surfaces in which the angle gradually changes without greatly changing the angle. Connected with round-shaped surfaces. Further, the protection part 74 does not protrude upward from the upper surface of the protection layer 29. As a result, the heating element plate 20 is not formed with a square shape at the connecting portion between the upper surface of the protective layer 29 and the heating element plate main scanning direction end surface 20a at both ends in the main scanning direction dm.

  Here, the manufacturing method of the thermal head 10 in this Embodiment is demonstrated with reference to FIG.

This embodiment is applied to a manufacturing process in which a plurality of thermal heads 10 are cut out from a single insulating plate 22a. First, an insulating plate 22a made of ceramic, for example, alumina (Al ₂ O ₃ ) is prepared. Next, a glass paste containing silicon oxide (SiO ₂ ) as a main component is applied onto the upper surface of the insulating plate 22a by screen printing or the like and baked and melted to form a glass layer 22b (S1).

  Thereafter, a wiring layer composed of the heating resistor layer 23 and the electrode layer 28 is formed on the surface of the glass layer 22b (S2). More specifically, first, a resistance material such as cermet is fixed to the surface of the insulating plate 22a and the surface of the glass layer 22b by sputtering or the like, and a conductive material such as aluminum is fixed thereon by sputtering or the like. Thereafter, the heating resistor layer 23 and the electrode layer 28 are patterned by etching, thereby forming the heating resistors 23a arranged at intervals in the main scanning direction dm and a gap corresponding to the heating portion 23b.

  Next, the protective layer 29 is fixed to the entire surface by sputtering or the like to protect the glass layer 22b, the heating resistor layer 23, the individual electrode 28a, and the common electrode 28b so as to remove the portion that becomes the bonding pad 26 in the individual electrode 28a. The layer 29 is formed (S3), and the heating element plate before division shown in FIG. 7 is created.

  After that, with the grooving blade having a flat front end in the main scanning direction dm and a width of about 3.0 to 4.0 mm, the dividing position Pd divided in the subsequent process is set to the plate thickness direction of the insulating plate 22a. Grooves to be ground to the upper half of the direction are performed (S4), thereby forming the groove part 70 as shown in FIG.

  Thereafter, the plate after the protective layer is formed is ground to the lower surface in the plate thickness direction with a dividing blade and divided into a plurality of heating element plates 20 (S5), so that one heating element plate as shown in FIG. 20 is created.

  The heating plate 20 thus formed is placed on the heat sink 30 together with the circuit board 40 (S6). Further, the heating plate 20 and the circuit board 40 are connected by the bonding wire 44 (S7), and the connection portion by the bonding wire 44 is sealed with the resin 48 (S8).

  Thereafter, for example, a thermosetting liquid resin material is applied to the groove portion 70 by a dispensing device as shown in FIG. 10, and then heated (S9). When a predetermined time has passed, the resin material has a shape in which the surface is connected to the upper surface of the protective layer 29 and the heating element plate main scanning direction end surface 20a in a smooth curved shape due to surface tension, as shown in FIG. It becomes the protection part 74. Then, the thermal head 10 is manufactured by finishing and polishing the protective portion 74 to adjust the shape (S10). This resin material is selected in consideration of the viscosity that does not sag from the groove 70 when applied, the surface properties after curing, and the wear resistance.

  As described above, the thermal head 10 is a resin having a curved surface between the upper surface of the heat generating plate 20 and the heat generating plate main scanning direction end surface 20a, and the upper surface and the heat generating plate main scanning direction end surface 20a are smooth. A protective part 74 connected to the slab is formed. Thereby, even if the heat generating plate 20 contacts the print medium 60, the thermal head 10 can prevent the print medium 60 from being streaked. In particular, when a film is used as the printing medium 60, the present invention is useful because it tends to be damaged more easily than paper or a card.

  In the thermal head 10, the width of the heat generating plate 20 in the main scanning direction dm is also shorter than the print medium 60, so that both ends of the heat generating plate 20 in the main scanning direction dm extend beyond the thermal ribbon 63. It has a structure that may come into contact with the printing medium 60. Even with such a structure, the thermal head 10 can prevent the print medium 60 from being damaged by the heat generating board 20 when the heat generating board 20 contacts the print medium 60.

  Here, like the heating element plate 220 shown in FIG. 12, the ends of the heating element plate 120 shown in FIG. 11 in the main scanning direction dm on the side separated from the circuit board are chamfered in a planar shape. By forming the portion 80, it is also conceivable to prevent streak-like scratches on the print medium 60. However, even such a heating element plate 220 is insufficient to prevent streak-like scratches on the printing medium 60, and the print quality may be deteriorated. Further, the conventional heating plate 220 (FIG. 12) has been chamfered in a flat shape by polishing, but requires a work man-hour for polishing the hard ceramic insulating plate 22a. The print medium 60 may be damaged.

  Furthermore, it is also conceivable to prevent streak-like scratches on the print medium 60 by chamfering both ends of the heating plate 120 in the main scanning direction dm into a curved shape. However, in such a case, a work man-hour is required for polishing the hard ceramic insulating plate 22a, and even if the polishing is performed, the printing medium 60 may be damaged.

  In contrast, the thermal head 10 according to the present embodiment forms the groove portion 70 by grinding with a grooving blade instead of polishing, thereby reducing the work man-hours compared to the polishing process and chamfering the ceramic substrate. Since the protective portion 74 is formed of the resin instead of the chamfered portion 80, the surface of the protective portion 74 can be made smoother and the print medium 60 can be made less likely to be damaged.

  Further, when the thermal head 10 uses the resin material of the resin 48 as the protective portion 74, it is not necessary to prepare a new resin material.

  According to the above configuration, the thermal head 10 is mounted on the heat sink 30, the circuit board 40 mounted on the upper surface of the heat sink 30 and mounting the drive IC 42, and mounted on the upper surface of the heat sink 30 adjacent to the circuit board 40. And a heating element plate 20 placed thereon. The heat generating plate 20 is an insulating plate 22a as an insulating substrate placed on the upper surface of the heat radiating plate 30 adjacent to the circuit board 40 in the sub-scanning direction ds, and a heat insulating layer formed on the upper surface of the insulating plate 22a. Glass layer 22b, a plurality of heating resistors 23a formed on the upper surface of the glass layer 22b and arranged at intervals in the main scanning direction dm and driven by the driving IC 42, and the heating resistors 23a on the surface of the heating resistor 23a The electrode layer 28 facing the surface of the surface 23a, the protective layer 29 formed on the upper surface of the glass layer 22b, and the bonding wire 44 connecting the electrode layer 28 and the driving IC 42, and the main scanning At both ends in the direction dm, the upper surface of the heating element plate 20 and the end surface in the main scanning direction dm of the heating element plate 20 are gradually bent at an angle of less than 90 degrees and do not protrude from the upper surface of the heating element plate 20. And to form a protective portion 74 is a resin to be connected by a curved surface shape.

  As a result, the thermal head 10 has both ends of the heating element plate 20 in the main scanning direction dm as compared with the case where the upper surface of the heating element plate 20 and the heating element plate main scanning direction end face 20a are connected at approximately 90 ° corners. The stress locally applied to the print medium 60 can be reduced, and the print medium 60 can be prevented from being damaged.

  In the thermal head 10 described above, a resin material is used for the protective portion 74. However, the present invention is not limited to this, and various materials such as glass may be used. In short, any material may be used as long as it is less likely to be damaged even if it contacts the printing medium 60 via the thermal ribbon 63.

  In the thermal head 10 described above, a thermosetting resin material is used for the protective portion 74, but the present invention is not limited to this, and a plastic resin material such as acrylic may be used.

  In the thermal head 10 described above, the resin material is applied to the groove portion 70 having the wall surface 71 perpendicular to the main surface of the insulating plate 22a and the bottom surface 72 orthogonal to the wall surface 71 and parallel to the main surface of the insulating plate 22a. However, the present invention is not limited to this, and the resin material may be applied to grooves having various shapes that can hold the resin material. In that case, grooving may be performed using a grooving blade corresponding to the shape of the groove. Moreover, the size of the groove part 70 may also be various sizes.

  Further, in the thermal head 10 described above, grinding is performed after grooving to create one heating element plate 20, but the present invention is not limited thereto, and the heating element is formed after grinding to create one heating element plate 20. The plate 20 may be grooved.

  Furthermore, in the thermal head 10 described above, the grooving process and the dividing process are performed in separate steps. However, the present invention is not limited to this, and for example, a wide grooving blade and a narrower width than the grooving blade are divided. The grooving process and the dividing process may be performed in the same process by combining the blade for use.

  Further, in the thermal head 10 described above, the resin material is applied to the groove portion 70 after the heating element plate 20 is placed on the heat dissipation plate 30 together with the circuit board 40. A resin material may be applied to the groove 70 before placing the heating element plate 20 on the plate 30.

  Further, in the thermal head 10 described above, the chamfered portion 68 is formed. However, the present invention is not limited to this, and the chamfered portion 68 may not be formed.

  Further, in the above-described thermal printer, the color of the thermal ribbon 63 is transferred to the printing medium 60. However, the present invention is not limited to this. good.

  DESCRIPTION OF SYMBOLS 10 ... Thermal head, 20 ... Heat generating body plate, 20a ... Heat generating body plate end surface in main scanning direction, 22 ... Support substrate, 22a ... Insulating plate, 22b ... Glass layer, 23 ... Heat generating resistor layer, 23a: Heat generating resistor, 23b: Heat generating portion, 24: Heat generating area, 26: Bonding pad, 28: Electrode layer, 28a: Individual electrode, 28b: Common electrode, 29: Protective layer, 30 ......... Heat sink, 40 ... Circuit board, 42 ... Drive IC, 44, 45 ... Bonding wire, 48 ... Resin, 50 ... Platen roller, 52 ... Axis, 60 ... Print medium, 63 ..... Thermal ribbon, 65, 66 ... Shaft, 68 ... Chamfer, 70 ... Groove, 71 ... Wall, 72 ... Bottom, 74 ... Protection, 80 ... Chamfer, Pd ... Dividing position, dm... Main scanning direction, ds.

Claims (2)

A heat sink,
A circuit board mounted on the upper surface of the heat sink and mounting a driving IC;
A heating element plate placed on the upper surface of the heat sink adjacent to the circuit board;
A thermal head comprising:
The heating plate is
An insulating substrate placed on the upper surface of the heat sink adjacent to the circuit board;
A heat insulating layer formed on the upper surface of the insulating substrate;
A plurality of heating resistors formed on the heat retaining layer and arranged in the main scanning direction at intervals, and driven by the driving IC;
An electrode layer facing the surface of the heating resistor across a gap on the surface of the heating resistor;
A protective layer formed on an upper surface of the heat retaining layer;
A bonding wire connecting the electrode layer and the driving IC;
Comprising
Protective portions made of resin that connect the upper surface of the heating element plate and the end surface of the heating element plate in the main scanning direction at both ends in the main scanning direction with curved surfaces that do not protrude from the upper surface of the heating element plate. A thermal head that is formed. The thermal head according to claim 1, wherein the protective portion has a round surface.

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