JP2014193563A - Thermal print head, thermal printer, and method for producing thermal print head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal print head suppressing the risk of disconnection while increasing the protruding height from the surface of a substrate in a heat generation region.SOLUTION: A head substrate 20 of the thermal print head is provided with a ceramic substrate 22, a glaze layer 25, a resistor layer 27, an electrode layer 28 and a protection film 29. The ceramic substrate 22 has a flat main surface 80 and a protrusion part 81 linearly extending. The glaze layer 25 has a top line most apart from the main surface 80 at a part coating the protrusion part 81. A planar polished surface, from which the protrusion part 81 protrudes, is formed in the vicinity of an upstream-side ridge line part in the sub-scanning direction of the protrusion part 81. On the resistor layer 27, heat generation resistors 26 are placed on the surface of the glaze layer 25 in the main scanning direction at intervals. An electrode connected to both end parts of the heat generation resistors 26 and carrying electricity to the heat generation resistors 26 is formed on the electrode layer 28. The protection film 29 coats the heat generation resistors 26, the electrode layer 28 and the glaze layer 25.

Description

  The present invention relates to a thermal print head, a thermal printer, and a method for manufacturing a thermal print head.

  A thermal print head is an output device that heats a plurality of heating resistors arranged on the surface of an insulating substrate and forms images such as characters and graphics on a printing medium such as thermal recording paper by the heat. 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. If the print medium is not heat sensitive, the ink is thermally transferred to the print medium by generating heat with a heat sensitive ink ribbon sandwiched between the print medium.

  In a thermal printer, a thermal print head has a heat radiator, a head substrate, and a circuit board. The head substrate having the heating resistor is fixed on the heat radiating body together with the circuit board. A drive element which is an IC (Integrated Circuit) is mounted on the circuit board. A bonding wire is bridged and electrically connected between the drive element and the head substrate. The driving element and the bonding wire are sealed with a sealing resin body.

  When printing on a hard medium, it is necessary to ensure a straight medium conveyance path that passes through the surface of the heating resistor portion of the head substrate. However, since the sealing resin body swells from the surface of the head substrate, it is difficult to secure such a linear medium transport path. Therefore, for example, Patent Document 1 discloses a method in which a trapezoidal protrusion is formed on one main surface of a ceramic substrate, a glaze layer is formed so as to cover the protrusion, and a heating resistor is arranged on the protrusion. It is disclosed.

  By forming the trapezoidal protrusion on one main surface of the ceramic substrate, the heating resistor can be formed at a position away from the main surface. As a result, the height from one main surface to the region where the heating resistor is formed can be made higher than the topmost portion of the sealing resin body, and it becomes easy to ensure a straight medium transport path.

JP-A-7-96621 Japanese Patent No. 2789418 Japanese Patent No. 3616809

  When a substrate having a protrusion is used as the head substrate of the thermal print head, the influence of the shape of the protrusion appears on the glaze layer covering the protrusion. As a result, in the ridge line portions on both sides of the protruding portion in the sub-scanning direction, a bulge may occur in the glaze layer corresponding to the ridge line of the protruding portion. This effect is particularly noticeable when the glaze layer is thinned. When the protrusion of the glaze layer is affected by the shape of the protrusion, disconnection may occur in the resistor or the electrode passing therethrough.

  Accordingly, an object of the present invention is to suppress the possibility of disconnection of an electrode while increasing the protruding height from the substrate surface of the portion where the heating resistors of the thermal print head are arranged.

  In order to solve the above-described problems, the present invention provides a thermal print head, comprising: a substrate having a flat surface and a protrusion protruding from the flat surface and extending linearly along the flat surface; A glaze layer having a top line farthest from the one principal surface at a portion covering the protrusion, a heating resistor arranged on the surface of the glaze layer at intervals in a direction in which the top line extends, and An electrode extending between one end of the heating resistor and an external connection terminal; and a protective film covering the heating resistor, the electrode, and the glaze layer, and the protruding portion across the electrode In the vicinity of the ridge line portion, a planar surface is formed in which the protruding portion is exposed without being covered with the glaze layer.

  Further, the present invention provides a thermal printer, a substrate having a flat surface and a protruding portion that protrudes from the flat surface and extends linearly along the flat surface, and a portion that covers the substrate and covers the protruding portion A glaze layer having a top line farthest from the one main surface, a heating resistor arranged on the surface of the glaze layer at intervals in a direction in which the top line extends, and one end of the heating resistor An electrode extending between the electrode and the external connection terminal, and a protective film covering the heating resistor, the electrode, and the glaze layer, wherein the glaze is formed in the vicinity of the ridge line portion of the projecting portion across the electrode. A thermal print head formed with a flat surface that is not covered with a layer and the protrusion is exposed; a drive element that generates heat from the heating resistor; a first transport unit that transports a printing medium; The print medium and the support A second conveying means for conveying a thermal ribbon between the print head, a cylindrical platen roller that presses the medium to be printed and the thermal ribbon against a region where the heating resistors of the thermal print head are arranged; It is characterized by comprising.

  According to another aspect of the present invention, there is provided a method of manufacturing a thermal print head, wherein a substrate forming step of forming a substrate having a flat surface and a protruding portion protruding from the flat surface and extending linearly along the flat surface; A glaze layer forming step of forming a glaze layer having a top line farthest from the one main surface in a portion covering and covering the protruding portion; and an upstream ridge line portion vicinity of the protruding portion in the sub-scanning direction. A polishing step of forming a planar polishing surface with the protrusions exposed by mechanical polishing, and a heating resistor arranged at intervals in the direction in which the top line extends on the surface of the glaze layer after the polishing step Forming a body and an electrode extending between one end of the heating resistor and the external connection terminal, and forming a protective film covering the heating resistor, the electrode and the glaze layer A process. And wherein the door.

  According to the present invention, it is possible to suppress the possibility of disconnection of the electrode while increasing the protruding height from the substrate surface of the portion where the heating resistors of the thermal print head are arranged.

It is sectional drawing of the head board | substrate in 1st Embodiment of the thermal print head which concerns on this invention. 1 is a partially cutaway plan view of a first embodiment of a thermal print head according to the present invention. It is sectional drawing of the thermal printer using 1st Embodiment of the thermal print head concerning this invention. It is sectional drawing in each manufacturing process of the head board | substrate of 1st Embodiment of the thermal print head concerning this invention. It is sectional drawing in each manufacturing process of the head board | substrate of 2nd Embodiment of the thermal print head concerning this invention. It is sectional drawing in each manufacturing process of the head board | substrate of 3rd Embodiment of the thermal print head concerning this invention. It is sectional drawing in each manufacturing process of the head board | substrate of 4th Embodiment of the thermal print head concerning this invention. It is sectional drawing in each manufacturing process of the head board | substrate of 5th Embodiment of the thermal print head which concerns on this invention.

An embodiment of a thermal print head according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or similar structure, and the overlapping description is abbreviate | omitted.
[First Embodiment]

  FIG. 1 is a sectional view of a head substrate in a first embodiment of a thermal print head according to the present invention. FIG. 2 is a partially cutaway plan view of the thermal print head according to the present embodiment. FIG. 3 is a cross-sectional view of a thermal printer using the thermal print head of the present embodiment.

  The thermal print head 11 of the present embodiment has a head substrate 20, a heat sink 30, and a circuit board 40. The head substrate 20 has a wiring layer composed of a ceramic substrate 22, a glaze layer 25, a resistor layer 27 and an electrode layer 28, and a protective film 29.

The ceramic substrate 22 which is an electrically insulating substrate is a ceramic rectangular plate such as alumina (Al ₂ O ₃ ). On one main surface 80 that is a flat surface of the ceramic substrate 22, a protruding portion 81 that protrudes from the main surface is formed. The protruding portion 81 extends in the long side direction (main scanning direction) of the ceramic substrate 22.

  The projecting portion 81 has a bottom portion 83 that decreases in width as it is connected to the main surface 80 and moves away from the main surface, and a top portion 82 that further protrudes from the bottom portion 83. The top portion 82 is sandwiched between side surfaces that are steeper than the skirt portion 83 with respect to the main surface 80. In the present embodiment, the side surfaces of the top portion 82 are all perpendicular to the main surface 80.

  The glaze layer 25 is a glass layer fused to the main surface 80 of the ceramic substrate 22 and the surface of the protruding portion 81. In the glaze layer 25, the protrusion 21 having the thickest thickness extends in the longitudinal direction of the ceramic substrate 22 at the center portion in the short direction of the top surface 84 of the ceramic substrate 22. On the glaze layer 25, a protrusion 21 having an arc-shaped cross section in the short direction (sub-scanning direction) is formed on the surface of the top surface 84 of the top portion 82. The surface of the ridge 21 of the glaze layer 25 has a smooth curved surface.

  Two ridge line portions extending in the main scanning direction of the top portion 82 of the protruding portion of the ceramic substrate 22 are polished together with the glaze layer 25 to form polished surfaces 71 and 72. On the polished surfaces 71 and 72, the protruding portion 81 of the ceramic substrate 22 is exposed without being covered with the glaze layer 25. The portion where the protruding portion 81 is exposed and the glaze layer 25 are smoothly connected. The polishing surfaces 71 and 72 are substantially flat.

  The resistor layer 27 and the electrode layer 28 are laminated on the surface of the glaze layer 25 in a predetermined pattern. On the resistor layer 27, the heating resistors 26 arranged at intervals in the main scanning direction are formed. The heating resistor 26 is formed so as to straddle the top line of the protrusion 21. In the electrode layer 28, electrodes connected to both ends of the heating resistor 26 in the sub-scanning direction of the ceramic substrate 22 are formed. The heating resistor 26 generates heat when a current flows through the electrodes formed on the electrode layer 28, and forms a belt-like heating region 24 extending in the main scanning direction.

  Most of the resistor layer 27 and the electrode layer 28 and the glaze layer 25 where the resistor layer 27 and the electrode layer 28 are not stacked are covered with a protective film 29. In the vicinity of one long side of the main surface 80 of the ceramic substrate 22, the protective film 29 is not formed, and the electrode layer 28 is exposed. This exposed portion becomes an external connection terminal.

  The head substrate 20 is placed on one surface of the heat sink 30. The head substrate 20 and the heat sink 30 are fixed with an adhesive, for example.

  The circuit board 40 is, for example, a flexible board, and is placed and fixed on the side of the heat sink 30 on which the head board 20 is placed via a hard board 41. On the circuit board 40, at least a part of a drive circuit for driving the heating resistor 26 is formed. The circuit board 40 is disposed adjacent to an edge on a side where a part of the electrode layer 28 is exposed without being covered with the protective film 29.

  A driving element 42 which is an IC (Integrated Circuit) is placed on the surface of the circuit board 40. The driving element 42 and the electrode layer 28 exposed without being covered with the protective film 29, that is, the external connection terminal are electrically connected by a bonding wire 44. A bonding wire is also bridged between the wiring of the circuit board 40 and the driving element 42. The exposed electrode layer 28, bonding wire 44, drive element 42, and the like are sealed with a sealing resin body 48.

  A connector 49 is attached to the circuit board 40. A drive circuit including the circuit board 40 and the drive element 42 is supplied with a control signal and electric power from the outside via the connector 49 to drive the head board 20 and heat the heat generating area 24 in a predetermined pattern.

  The thermal printer includes a thermal print head 11, a platen roller 60, a delivery side ribbon roller 64, a take-up side ribbon roller 63, and two ribbon guides 65. The platen roller 60 is formed in a cylindrical shape having an axis in the normal direction of the heat generating region 24 of the thermal print head 11. The side surface of the platen roller 60 has a certain degree of elasticity.

  The feeding-side ribbon roller 64, the winding-side ribbon roller 63, and the ribbon guide 65 are disposed closer to the heat radiating plate 30 than the heat generating region 24 of the thermal print head 11. The feeding-side ribbon roller 64 and one ribbon guide 65 are arranged on the upstream side, that is, on the circuit board 40 side with respect to the heat generating region 24 of the thermal print head 11. The winding-side ribbon roller 63 and the other ribbon guide 65 are disposed on the downstream side with respect to the heat generating region 24 of the thermal print head 11.

  The delivery-side ribbon roller 64 is obtained by winding an unused ink ribbon 62. The take-up side ribbon roller 63 rotates the used ink ribbon 62 by being rotated by a rotation mechanism (not shown). The ribbon guide 65 changes the transport direction of the ink ribbon 62.

  The direction of the ink ribbon 62 delivered from the delivery-side ribbon roller 64 is changed by the ribbon guide 65 and heads toward the heat generating area 24 of the thermal print head 11. The direction of the ink ribbon 62 whose direction is changed on the arc-shaped surface near the heat generating region 24 of the thermal print head 11 is changed by another ribbon guide 65 and is directed to the take-up side ribbon roller 63.

  The print medium 61 moves in the sub-scanning direction while being pressed against the heat generating area 24 of the thermal print head 11 by the platen roller 60. At this time, the ink ribbon 62 is interposed between the printing medium 61 and the heat generating region 24. At the time of printing on the printing medium 61, current is supplied from the driving circuit such as the driving element 42 to the heating resistor 26 by a signal supplied from the outside and the like, and heat is generated. A desired image is printed on the printing medium 61 by moving the printing medium 61 in the sub-scanning direction while changing the heating pattern of the heating area 24 of the thermal print head 11.

  The used portion used for printing the ink ribbon 62 is sequentially sent to the take-up side ribbon roller 63. The ink ribbon 62 is conveyed while being in contact with the vicinity of the ridge 21 of the thermal print head 11 and the ribbon guide 65 by the ink ribbon feeding mechanism including the feeding side ribbon roller 64, the winding side ribbon roller 63, the ribbon guide 65, and the like. Is done.

  The ink on the ink ribbon 62 is melted by the heat generated in the heat generating area 24 and transferred to the printing medium 61. The ink ribbon 62 and the printing medium 61 are in contact with each other in the heat generating area 24, but are separated from the heat generating area 24 as well. Due to the adhesive force of the ink melted in the vicinity of the heat generating area 24, the ink ribbon 62 moves to the downstream side to some extent while sticking to the printing medium 61. Thereafter, the adhesive force decreases due to solidification of the melted ink, and the ink ribbon 62 moving in a direction different from the printing medium 61 is peeled off from the printing medium 61.

  Next, a method for manufacturing the thermal print head will be described.

  FIG. 4 is a cross-sectional view in each manufacturing process of the head substrate of the thermal print head of the present embodiment.

  First, as shown in FIG. 4A, a ceramic plate 90 having a thickness equal to or greater than the thickness from the bottom surface of the ceramic substrate 22 to the top surface 84 of the protruding portion 81 is formed. Next, the ceramic plate 90 is covered with a mask, and the surface of the ceramic plate is shaved by sandblasting. This mask covers a region corresponding to the protruding portion 81 of each ceramic substrate 22 so that abrasive particles used for sandblasting do not pass through the region. The width of the slit through which the abrasive particles pass is, for example, 1 mm, and the slit pitch is, for example, 3 mm. As the mask, for example, a resin film having a thickness of about 200 μm can be used.

  In grinding by sandblasting, the portion sandwiched between the surfaces becomes difficult to be scraped off, so that a hem 83 having a predetermined size can be formed by grinding with a suitable particle abrasive. As the particulate abrasive, silicon carbide (SiC) having a particle size of about 100 μm can be used. In this way, the ceramic substrate 22 having the protrusions 81 as shown in FIG. 4B is formed.

  Next, as shown in FIG. 4C, the glass paste 91 is coated to a uniform thickness on the surface of the ceramic substrate 22 on the side where the protruding portions 81 are formed. Since the top part 82 exists in the protrusion part 81 of the ceramic substrate 22, and the top part 82 is pinched | interposed by the side surface upright from the main surface, application | coating of the glass paste by screen printing is difficult. For this reason, it is preferable to use a spray coat for the coating of the glass paste.

  Thus, after coating the glass paste on the surface of the ceramic substrate 22 where the protrusions 81 are formed, the glaze layer 25 is formed by holding and baking at a temperature equal to or higher than the softening point of the glass. Is done. With the glass softened, it flows by the action of gravity and surface tension, and the surface of the glaze layer 25 draws a smooth curved surface.

  However, if the glaze layer 25 is thinned in order to improve the thermal responsiveness during the operation of the thermal print head 11, the surface shape of the glaze layer 25 is along the ridgeline at the ridgeline portions on both sides of the top surface 84 of the protrusion 81 of the ceramic substrate 22. It will become the shape. That is, as shown in FIG. 4D, a protrusion 93 is formed on this ridge line portion.

  If there is such a protrusion 93, there is a high possibility that the resistor layer 27 and the electrode layer 28 will be disconnected. Further, the shape of the bulge 93 also appears on the surface of the protective film 29, which may hinder smooth conveyance of the thermal ribbon 62.

  Therefore, in the present embodiment, the protrusion 93 is removed by mechanical polishing. The polishing surface 92 is planar. The protrusion 93 is polished from the glaze layer 25 until the protruding portion 81 of the ceramic substrate 22 is partially exposed. In this way, as shown in FIG. 4E, the polished surfaces 71 and 72 are formed in which the protruding portions 81 of the ceramic substrate 22 are exposed without being covered with the glaze layer 25. By performing the mechanical polishing, the portion where the protrusion 81 is exposed and the glaze layer 25 are smoothly connected. Since the main purpose of the mechanical polishing is to remove the protrusion 93, it may be advanced to a stage where the ceramic substrate 22 is exposed over the entire main scanning direction.

  After this polishing, the resistor layer 27 and the electrode layer 28 are laminated on the surface of the glaze layer 25 and the exposed protrusion 81 by sputtering or the like. Thereafter, the laminated resistor layer 27 and electrode layer 28 are patterned by a photolithography technique or the like to form the heating resistor 26 and predetermined wiring. Thereafter, the protective film 29 is formed by a sputtering method or the like. Thereby, the head substrate 20 is completed (FIG. 4F).

  Here, one head substrate 20 is formed from a single ceramic plate 90, but the ceramic plate 90 has a size corresponding to a plurality of ceramic substrates 22, and a plurality of heads are simultaneously used. The substrate 20 may be formed. In this case, after the plate corresponding to the plurality of head substrates 20 is formed, each head substrate 20 may be cut out.

  The head substrate 20 and a separately manufactured circuit board 40 are placed on the heat sink 30 and fixed. Further, the driving element 42 is placed on the circuit board 40 and the bonding wire 44 is bridged. Thereafter, the drive element 42 and the bonding wire 44 are sealed with a sealing resin body 48. Further, the thermal print head 11 is completed by attaching the connector 49 and the like.

  As described above, according to the present embodiment, since the protruding portion 81 protruding from the main surface 80 of the ceramic substrate 22 is provided, the protruding height from the main surface of the heat generating region 24 in which the heating resistors 26 are arranged is set. Can be increased. Since the projecting portion 81 is provided with the top portion 82, the spread of the bottom of the glaze layer 25 can be suppressed, and the width of the head substrate 20 in the sub-scanning direction can be reduced.

  Further, since the ridge line portions on both sides of the top surface 84 of the protruding portion 81 in the sub-scanning direction are polished to form the polished surfaces 71 and 72, the protrusion 93 along the shape of the protruding portion 81 does not remain. As a result, the possibility of disconnection in the resistor layer 27 and the electrode layer 28 is small.

  Further, when the protruding portion 81 is formed by sandblasting, unevenness may occur on the ridge line portions on both sides of the top surface 84 in the sub-scanning direction. However, in the present embodiment, since the ridge portion is scraped off by mechanical polishing, the resistor layer 27 and the electrode layer 28 can be formed on a smooth flat surface with less unevenness.

Further, by forming the polished surfaces 71 and 72, the glaze layer 25 deposited on the top surface 84 of the protruding portion 81 and the glaze layer 25 deposited on the side surface of the top portion 82 of the protruding portion 81 are separated. For this reason, these glaze layers 25 are substantially insulative, and the heat generated in the heat generating region 24 is substantially stored only in the glaze layer 25 deposited on the top surface 84. For this reason, thermal responsiveness improves.
[Second Embodiment]

  FIG. 5 is a cross-sectional view in each manufacturing process of the head substrate of the second embodiment of the thermal print head according to the present invention.

  In the present embodiment, as in the first embodiment, a ceramic plate 90 having a thickness equal to or greater than the thickness from the bottom surface of the ceramic substrate 22 to the top surface 84 of the protruding portion 81 is formed as shown in FIG. . Next, the ceramic plate 90 is polished with a dicer or the like to form a protrusion 81 having a trapezoidal cross section as shown in FIG.

  Next, as shown in FIG. 5C, the glass paste 91 is coated on the surface of the ceramic substrate 22 on the side where the protruding portions 81 are formed. In the present embodiment, since the side surface of the protrusion 81 is an inclined surface, it is possible to apply glass paste by screen printing depending on the angle.

  Thus, after coating the glass paste on the surface of the ceramic substrate 22 where the protrusions 81 are formed, the glaze layer 25 is formed by holding and baking at a temperature equal to or higher than the softening point of the glass. Is done. With the glass softened, it flows by the action of gravity and surface tension, and the surface of the glaze layer 25 draws a smooth curved surface.

  However, if the glaze layer 25 is thinned in order to improve the thermal responsiveness during the operation of the thermal print head 11, the surface shape of the glaze layer 25 is along the ridgeline at the ridgeline portions on both sides of the top surface 84 of the protrusion 81 of the ceramic substrate 22. It will become the shape. That is, as shown in FIG. 5D, a protrusion 93 is formed on this ridge line portion.

  Therefore, this protrusion 93 is removed by mechanical polishing. The polishing surface 92 is planar. The protrusion 93 is polished from the glaze layer 25 until the protruding portion 81 of the ceramic substrate 22 is partially exposed. In this way, as shown in FIG. 5E, a polished surface 71 is formed in which the protruding portion 81 of the ceramic substrate 22 is exposed without being covered with the glaze layer 25. In the present embodiment, only the ridge line portion on the upstream side of the heat generation region 24 of the protrusion 81, that is, the ridge line portion on the circuit board side is polished.

  After this polishing, the resistor layer 27 and the electrode layer 28 are laminated on the surface of the glaze layer 25 and the exposed protrusion 81 by sputtering or the like. Thereafter, the laminated resistor layer 27 and electrode layer 28 are patterned by a photolithography technique or the like to form a heating resistor or a predetermined wiring. Thereafter, the protective film 29 is formed by a sputtering method or the like. Thereby, the head substrate 20 is completed (FIG. 5F).

  Also in the head substrate 20 of the present embodiment, since the ridge line portion that the electrode extending between the heating resistor and the external connection terminal crosses is polished flat, the possibility of disconnection is small. Further, the disconnection portion 94 is formed so that the resistor layer 27 and the electrode layer 28 on the downstream side of the heat generating region 24, that is, the side opposite to the circuit board, are electrically independent from the heat generating resistor. That is, on the electrical circuit, the resistor layer 27 and the electrode layer 28 on the downstream side of the heat generating region 24 are not present. For this reason, there is no problem even if a disconnection occurs due to the fact that the ridge line portion on the downstream side of the heat generation region 24 of the protrusion 81 is not polished. In addition, the adhesion of the protective film 29 is improved by providing the resistor layer 27 and the electrode layer 28 in this portion.

As described above, according to the present embodiment, since the protruding portion 81 protruding from the main surface 80 of the ceramic substrate 22 is provided, the protruding height from the main surface of the heat generating region 24 in which the heating resistors 26 are arranged is set. Can be increased. Further, since the ridge line portion on the upstream side in the sub-scanning direction of the top surface 84 of the protruding portion 81 is polished to form the polishing surface 71, the protrusion 93 along the shape of the protruding portion 81 does not remain. As a result, there is little possibility of disconnection of the resistor layer 27 and the electrode layer 28 in an electrically necessary portion.
[Third Embodiment]

  FIG. 6 is a cross-sectional view in each manufacturing process of the head substrate of the third embodiment of the thermal print head according to the present invention.

This embodiment is different from the second embodiment in that the ridge line portions on both sides of the top surface of the protruding portion 81 of the ceramic substrate 22 are curved. Even in such a ceramic substrate 22, when the glaze layer 25 is made thinner, the surface shape of the glaze layer 25 at the ridge line portion becomes along the shape of the protruding portion 81. Therefore, in such a case, the glaze layer 25 and the protruding portion 81 are mechanically polished at the ridge line portion to obtain a planar surface, and the possibility that the resistor layer 27 and the electrode layer 28 are disconnected is reduced. it can.
[Fourth Embodiment]

  FIG. 7 is a cross-sectional view in each manufacturing process of the head substrate of the fourth embodiment of the thermal print head according to the present invention.

This embodiment is different from the first embodiment in that the protruding portion 81 does not have the skirt portion 83 and protrudes with substantially the same width. Even in such a ceramic substrate 22, a planar surface is obtained by mechanically polishing the glaze layer 25 and the protrusion 81 at the ridge line portion of the protrusion 81, and the resistor layer 27 and the electrode layer 28 are disconnected. It is possible to reduce the possibility of occurrence.
[Fifth Embodiment]

  FIG. 8 is a sectional view in each manufacturing process of the head substrate of the fifth embodiment of the thermal print head according to the present invention.

This embodiment is different from the first embodiment in that the skirt 83 of the protrusion 81 is not a curved surface but a plane. Such a protrusion 81 can be formed by dicing using a blade having a shape along the skirt 83. Even in such a ceramic substrate 22, a planar surface is obtained by mechanically polishing the glaze layer 25 and the protrusion 81 at the ridge line portion of the protrusion 81, and the resistor layer 27 and the electrode layer 28 are disconnected. It is possible to reduce the possibility of occurrence.
[Other embodiments]

  The above-described embodiments are merely examples, and the present invention is not limited to these. Moreover, it can also implement combining the characteristic of each embodiment.

DESCRIPTION OF SYMBOLS 11 ... Thermal print head, 20 ... Head substrate, 21 ... Projection, 22 ... Ceramic substrate, 24 ... Heat generation area, 25 ... Glaze layer, 26 ... Heat generation resistor, 27 ... Resistance layer, 28 ... Electrode layer, 29 ... Protective film, 30 ... Radiation plate, 40 ... Circuit board, 41 ... Hard substrate, 42 ... Drive element, 44 ... Bonding wire, 48 ... Sealing resin body, 49 ... Connector, 60 ... Platen roller, 61 ... Printing medium, 62 ... Ink ribbon, 63 ... Winding side ribbon roller, 64 ... Delivery side ribbon roller, 65 ... Ribbon guide, 71 ... Polishing surface, 72 ... Polishing surface, 80 ... Main surface, 81 ... Projection, 82 ... Top, 83 ... hem, 84 ... top surface, 90 ... ceramic plate, 91 ... glass paste, 92 ... polishing surface, 93 ... projection

Claims (7)

A substrate having a flat surface and a protrusion protruding from the flat surface and extending linearly along the flat surface;
A glaze layer having a top line farthest from the one main surface at a portion covering the substrate and covering the protruding portion;
Heating resistors arranged on the surface of the glaze layer at intervals in the direction in which the top line extends;
An electrode extending between one end of the heating resistor and the external connection terminal;
A protective film covering the heating resistor, the electrode, and the glaze layer;
Comprising
A thermal print head characterized in that a planar surface is formed in the vicinity of a ridge line portion of the projecting portion that is traversed by the electrode and is not covered with the glaze layer and the projecting portion is exposed.   2. A planar surface in which the protruding portion is exposed without being covered with the glaze layer is also formed in the vicinity of the ridge line portion of the protruding portion on the side opposite to the direction across the electrode. The thermal print head described in 1.   The said protrusion part consists of the bottom part which protrudes while the width | variety narrows from the said flat surface side, and the top part pinched | interposed by the side surface where the inclination with respect to the said flat surface is steeper than the skirt part. Thermal print head.   The thermal print head according to claim 1, wherein the heating resistor extends across the top line. A substrate having a flat surface and a protrusion projecting from the flat surface and extending linearly along the flat surface; and a portion that covers the substrate and covers the protrusion, the topmost furthest from the one main surface A glaze layer having a line, a heating resistor arranged on the surface of the glaze layer with an interval in the direction in which the top line extends, and extending between one end of the heating resistor and an external connection terminal An electrode, a heating resistor, a protective film that covers the electrode and the glaze layer, and the protrusion is not covered by the glaze layer in the vicinity of a ridge line portion of the protrusion that the electrode crosses. A thermal print head on which an exposed flat surface is formed;
A drive element for generating heat from the heating resistor;
First conveying means for conveying a printing medium;
Second conveying means for conveying a thermal ribbon between the printing medium and the thermal print head;
A cylindrical platen roller that presses the printing medium and the thermal ribbon against a region where the heating resistors of the thermal print head are arranged;
A thermal printer comprising: Forming a substrate having a flat surface and a protrusion protruding from the flat surface and extending linearly along the flat surface; and
A glaze layer forming step of forming a glaze layer having a top line farthest from the one main surface in a portion covering the substrate and covering the protruding portion;
A polishing step of mechanically polishing the vicinity of the ridge line portion on the upstream side in the sub-scanning direction of the protrusion to form a planar polishing surface in which the protrusion is exposed;
After the polishing step, a heating resistor arranged on the surface of the glaze layer with an interval in the direction in which the top line extends, and an electrode extending between one end of the heating resistor and the external connection terminal And a step of forming
Forming a protective film covering the heating resistor, the electrode, and the glaze layer;
A method of manufacturing a thermal print head, comprising: The substrate forming step is characterized in that a ceramic flat plate is sandblasted to form a substrate having a flat surface and a projecting portion protruding from the flat surface and extending linearly along the flat surface. Manufacturing method of thermal print head.

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