JP2019031057A - Thermal print head and thermal printer - Google Patents

Abstract

To improve durability of a thermal print head.SOLUTION: A thermal print head includes: a substrate having a first surface facing a printing medium and an inclined surface having a surface which is continuous to the first surface and is inclined to the first surface; a first heat storage layer formed so as to cover a corner part forming a boundary between the first surface and the inclined surface; a second heat storage layer formed on the first surface; a heating part formed on the first heat storage layer; and an electrode which is formed on the first heat storage layer and the second heat storage layer and is electrically connected to the heating part.SELECTED DRAWING: Figure 2

Description

  Embodiments described herein relate generally to a thermal print head and a thermal printer.

  A thermal print head is an output device that heats a plurality of resistors arranged in a heat generating area and forms images such as characters and figures on a heat-sensitive printing medium or the like by the heat. This thermal print 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.

  In recent years, printing media have been hardened and printing speed has been increased. As the printing medium is hardened, the impact when the printing medium comes into contact with the thermal print head is increasing. As the printing speed is increased, the pressing force with which the platen roller presses the thermal print head via the printing medium is increased. As the impact and pressing force increase, further improvement in durability of the thermal print head is desired.

JP 2013-202968 A

  The present invention has been made under the above circumstances, and an object thereof is to improve the durability of a thermal print head.

  In order to solve the above problems, a thermal print head according to the present embodiment includes a first surface facing a printing medium, and a slope having a surface that is continuous with the first surface and is inclined with respect to the first surface. A first heat storage layer formed to cover a substrate, a corner portion forming a boundary between the first surface and the slope, a second heat storage layer formed on the first surface, and the first A heat generating part formed on one heat storage layer, and an electrode formed on the first heat storage layer and the second heat storage layer and electrically connected to the heat generating part.

  In addition, the thermal printer according to the present embodiment includes the thermal print head according to the present embodiment, a transport mechanism that transports the print medium onto a heat generating unit included in the thermal print head, and presses the print medium against the heat generating unit. A platen roller.

FIG. 3 is a top view of the thermal print head according to the first embodiment. 1 is a cross-sectional view of a head substrate according to a first embodiment. It is a top view of the head substrate according to the first embodiment. 1 is a cross-sectional view of a circuit board according to a first embodiment. It is a figure for demonstrating the connection of the head board | substrate which concerns on 1st Embodiment, and a circuit board. 1 is a cross-sectional view of a thermal printer according to a first embodiment.

<< First Embodiment >>
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. In addition, this embodiment is an illustration and the technical scope of this invention is not limited to this. Further, the drawings are schematic, and dimensions and the like are different from actual ones.

  FIG. 1 is a top view of a thermal print head 100 according to the first embodiment. As shown in FIG. 1, the thermal print head 100 includes a heat sink 20, a head substrate 30, and a circuit board 40. The head substrate 30 and the circuit board 40 are fixed on the main surface of the heat sink 20 with an adhesive adjacent to each other. As the adhesive, a thermosetting resin adhesive such as a double-sided adhesive tape or a soft silicone resin can be used. Here, the direction X shown in FIG. 1 is the main scanning direction, and the direction Y is the sub-scanning direction that is the moving direction of the printing medium.

  The heat sink 20 is a flat plate made of a metal having high thermal conductivity such as aluminum.

The head substrate 30 has a function of printing on the printing medium 70. As shown in FIG. 1, the head substrate 30 is a member having the main scanning direction X as a longitudinal direction. As shown in FIG. 2, the head substrate 30 includes a first heat storage layer 10a and a second heat storage layer 10b that form a support substrate 9 and a glaze layer. The support substrate 9 is made of an insulating material having heat resistance, and is made of, for example, ceramics such as alumina. The support substrate 9 may be SiN, SiC, quartz, AlN, or fine ceramics containing Si, Al, O, N, or the like. The first heat storage layer 10 a and the second heat storage layer 10 b forming the glaze layer are made of, for example, a glass film or a resin film made of SiO ₂ and are laminated on the support substrate 9. The 1st heat storage layer 10a and the 2nd heat storage layer 10b which form a glaze layer can be formed, for example, after printing on the support substrate 9 the glass paste which mixed the powder of glass with the organic solvent, and baking it.

  As shown in FIG. 2, the support substrate 9 is connected to the first surface 9a, the second surface 9b opposite to the first surface 9a, the side surface 9c, and the first surface 9a, and the inclined surface 9d inclined with respect to the first surface 9a. have. The corner that forms the boundary between the first surface 9a and the slope 9d is defined as a first corner 9e. A corner portion that forms a boundary between the side surface 9c and the inclined surface 9d is defined as a second corner portion 9f.

  A first heat storage layer 10a is formed so as to cover the first corner 9e. The first heat storage layer 10a is formed of a material having low thermal conductivity (for example, glass or the like), and suppresses heat generated in the heat generating portion 14 (heat generating resistor) from being radiated to the support substrate 9 side. Since the volume of the 1st heat storage layer 10a formed on the 1st corner | angular part 9e is small and the heat capacity is also small, the amount of heat accumulate | stored in the 1st heat storage layer 10a is small. The first heat storage layer 10a is formed so as to rise above the first virtual surface extending from the first surface 9a of the support substrate 9 onto the inclined surface 9d. The first heat storage layer 10a is formed so as to cover the first corner portion 9e and the inclined surface 9d. Moreover, the 2nd thermal storage layer 10b is formed so that the 1st surface 9a may be covered.

  The first heat storage layer 10a and the second heat storage layer 10b are formed apart from each other in the Y-axis direction. By separating the first heat storage layer 10a and the second heat storage layer 10b, the heat capacity of the first heat storage layer 10a is reduced.

  Here, a method for producing the head substrate 30 will be described. The support substrate 9 is a rectangular flat plate having a thickness of about 0.5 mm to 1.0 mm made of alumina ceramic, for example. As shown in FIG. 2, one end of the support substrate 9 is cut obliquely to form a slope 9d. A first heat storage layer 10a and a second heat storage layer 10b that form a glaze layer made of glass are formed on the support substrate 9. Specifically, a glass paste obtained by mixing glass powder with an organic solvent is printed on the support substrate 9 and then baked to form the first heat storage layer 10a and the second heat storage layer 10b. Moreover, after printing and baking a glass paste on the support substrate 9, the part which separates the 1st thermal storage layer 10a and the 2nd thermal storage layer 10b may be etched away by a photoengraving process, and you may bake again.

  Next, the resistor layer 11 and the conductor layer 12 are sequentially laminated on the first heat storage layer 10a and the second heat storage layer 10b by a thin film forming apparatus such as a sputtering apparatus. The resistor layer 11 and the conductor layer 12 are electrically connected. Thereafter, the resistor layer 11 and the conductor layer 12 are formed by a photo-engraving process. The conductor layer 12 becomes the individual electrode 15, the common electrode 16, and the connection portion 17. The individual electrode 15 and the common electrode 16 are arranged with a width of G and a pitch of P. Subsequently, the portion (width G, length L) indicated by hatching in FIG. 3 of the conductor layer 12 is removed by etching. The portion of the resistor layer 11 from which the conductor layer 12 has been removed by etching becomes the heat generating portion 14. As shown in FIG. 3, the heat generating portions 14 are formed in an array at a pitch P in the main scanning direction X. The area (pitch / inch) of pixels printed on the printing medium is determined by the area of the heat generating portion 14 and the pitch P. An individual electrode 15 or a common electrode 16 is connected to one end of the heat generating part 14. The other end of the heat generating part 14 is connected to the other end of the other heat generating part 14 via a connection part 17.

  Further, a protective film 13 that covers the individual electrode 15, the common electrode 16, and the heat generating portion 14 is formed. In order to connect the individual electrode 15 and the common electrode 16 to a circuit board 40 to be described later by a bonding wire 42, an opening is provided in the protective film 13 at a corresponding portion of the individual electrode 15 and the common electrode 16.

The resistor layer 11 is made of, for example, a TaSiO, NbSiO, TaSiNO, or TiSiCO-based electrical resistor material. The conductor layer 12 is formed using, for example, a metal such as Al, Cu, or AlCu alloy as a main material. The protective film 13 is formed of a hard and dense insulator material having high thermal conductivity such as a SiO ₂ film, a SiN film, a SiON film, or a SiC film. It is preferable that the surface material of the protective film 13 contains at least Si and carbon since the thermal conductivity is increased. This protective film 13 covers at least the heat generating portion 14, the individual electrode 15, and the common electrode 16, and is subjected to thermal printing from corrosion caused by pressure contact or sliding contact of the printing medium by the platen roller 50 and contact with moisture in the atmosphere. It has a function of protecting the head 100. The head substrate 30 is produced as described above.

  The circuit board 40 has a function of supplying current to the head substrate 30 based on the control of the control device 80. As illustrated in FIG. 4, the circuit board 40 is disposed on the main surface of the heat sink 20 so as to be adjacent to the head substrate 30.

  FIG. 5 is a diagram for explaining the connection between the head substrate 30 and the circuit substrate 40. A predetermined number of driving ICs 41 are mounted on the upper surface of the circuit board 40 near the head substrate 30. A connector 44 is mounted on the other end. The driving IC 41 and the connector 44 are connected by printed wiring or the like. A plurality of driving ICs 41 are mounted on the circuit board 40 in accordance with the number of heat generating portions 14 of the head substrate 30. FIG. 5 shows a case where there is one driving IC 41. The driving IC 41 is a control element having a switching function capable of controlling the current supplied to the heat generating unit 14. Specifically, the driving IC 41 controls whether to supply current from the power supply device 90 for each heat generating part 14 of the head substrate 30 based on a control signal received from the control device 80 via the connector 44. . The output of the driving IC 41 is electrically connected to the individual electrode 15 and the common electrode 16 of the head substrate 30 through bonding wires 42.

  As shown in FIG. 4, the driving IC 41 and the bonding wire 42 are sealed with a sealing material 43 made of an epoxy resin. The driving IC 41 and the bonding wire 42 are protected by the sealing material 43. An epoxy resin coating, which is a thermosetting resin, is applied as the sealing material 43 and is thermally cured by heat treatment at about 100 ° C. for several hours. The sealing material 43 may also protect the individual electrodes 15 and the common electrode 16 of the head substrate 30 and the wiring portion of the circuit board 40. As the sealing material 43, an epoxy resin coating which is a thermosetting resin is mainly used, but a silicon resin having a certain degree of flexibility after thermosetting may be used.

  Next, the operation of the head substrate 30 will be described. A current is supplied to the head substrate 30 between the individual electrodes 15 and the common electrode 16 based on control by the circuit board 40. In the portion where the resistor layer 11 and the conductor layer 12 are in contact, the current supplied from the circuit board 40 flows through the conductor layer 12 having a low resistance, so that the resistor layer 11 does not generate heat. However, in the portion where the conductor layer 12 is removed by etching, the current flows through the resistor layer 11 having a high resistance, so that the resistor layer 11 generates heat. The portion of the resistor layer 11 from which the conductor layer 12 is removed by etching functions as the heat generating portion 14.

  Next, a thermal printer 200 including the thermal print head 100 described above will be described with reference to FIG. FIG. 6 is a schematic sectional view of the thermal printer 200. As shown in FIG. 6, the thermal printer 200 includes the thermal print head 100, the platen roller 50, and the transport mechanism 60 described above.

  The transport mechanism 60 transports the print medium 70 and the ink ribbon 71 adhered to the print medium 70 in the sub-scanning direction Y by the transport medium 61. The platen roller 50 presses the print medium 70 and the ink ribbon 71 together with the transport medium 61 against the vicinity of the heat generating portion 14 of the head substrate 30. The driving IC 41 of the circuit board 40 receives a control signal from the control device 80 and supplies a current from the power supply device 90 to the corresponding heat generating portion 14 so that the heat generating portion 14 corresponding to the pixel of the image to be printed generates heat. The driving IC 41 performs high-speed control of on / off of energization to the heat generating unit 14 in accordance with the moving speed of the printing medium 70 by the transport mechanism 60. The heat generating part 14 generates heat while a current is supplied. The ink on the ink ribbon 71 pressed against the head substrate 30 by the platen roller 50 melts only the portion of the ink located on the heat generating portion 14 that generates heat, and adheres to the printing medium 70.

  The remaining heat obtained by melting the ink of the ink ribbon 71 is radiated through the first heat storage layer 10 a having a small heat capacity, the support substrate 9, and the heat radiating plate 20. Since the first heat storage layer 10a has a small heat capacity, the temperature of the first heat storage layer 10a changes at high speed following the high-speed temperature change of the heat generating portion 14. If the first heat storage layer 10a maintains the high temperature state for a long time after the current supply to the heat generating unit 14 is stopped, the high temperature state continues around the heat generating unit 14 to which no current is supplied. As a result, a blurred image is formed on the print medium 70. In the thermal print head 100 according to the present embodiment, the temperature of the first heat storage layer 10a also changes at a high speed following the high-speed temperature change of the heat generating portion 14, so that the thermal printer 200 prints as the print medium 70 moves at a high speed. A clear image can be formed on the medium 70.

  As described above, in the thermal print head 100 according to the present embodiment, the first heat storage layer 10a is formed so as to cover the first corner portion 9e that forms the boundary between the first surface 9a of the support substrate 9 and the inclined surface 9d. ing. When the 1st heat storage layer 10a is not formed in the 1st corner | angular part 9e, the electrode and protective film 13 which are formed in the 1st corner | angular part 9e are easy to peel, and durability falls. However, the durability of the thermal print head can be improved by forming the first heat storage layer 10a so as to cover the first corner portion 9e.

  The first surface 9a of the support substrate 9 is covered with a second heat storage layer 10b. As the thermal print head 100 is downsized, the electrodes formed on the head substrate 30 are thinner. The second heat storage layer 10b protects the thin electrodes (individual electrode 15 and common electrode 16). Thereby, the durability of the thermal print head can be improved.

  Further, the first heat storage layer 10a and the second heat storage layer 10b are formed separately. Therefore, the volume of the first heat storage layer 10a is small, and its heat capacity is small. Therefore, even if the heat generating part 14 is turned on / off at high speed, the first heat storage layer 10a can change temperature at high speed corresponding to the on / off, and the temperature in the vicinity of the heat generating part 14 is also changed. It changes at high speed corresponding to the control speed. Thereby, the thermal responsiveness of the thermal print head 100 can be improved.

  When the first heat storage layer 10a and the second heat storage layer 10b are connected by a thick glaze layer, when the glaze layer is fired, the glaze is drawn to the second heat storage layer 10b having a large volume due to the firing temperature, etc. The first heat storage layer 10a may not be formed with a desired thickness on the first corner 9e. Conversely, the first heat storage layer 10a may become too thick, which may hinder the conveyance of the printing medium 70. In the thermal print head 100 according to this embodiment, by forming the first heat storage layer 10a and the second heat storage layer 10b apart from each other, the unexpected glaze movement can be eliminated, and the first corner portion 9e A glaze layer (first heat storage layer 10a) having a desired thickness can be stably formed.

  Further, by forming the first heat storage layer 10a so as to cover the first corner 9e, the first heat storage layer 10a is more than the first virtual surface extending from the first surface 9a of the support substrate 9 onto the inclined surface 9d. It is formed up to the top. That is, the heat generating area near the heat generating portion 14 to which the printing medium 70 is pressed protrudes from the first surface 9 a of the support substrate 9. As a result, a straight conveyance path for the printing medium 70 can be secured, and the rigid printing medium 70 can be conveyed at high speed.

  In the above description, the case where printing is performed on the print medium 70 using an ink ribbon has been described. However, the printing method is not necessarily limited to this. For example, the printing medium 70 may be thermal paper. When the printing medium 70 is thermal paper, the pixels of the printing medium 70 located on the heat generating portion 14 that generates heat by energization are heated and colored.

  FIG. 5 is a diagram in which the driving IC 41 switches all the wirings. However, the wiring pattern shown in FIG. 5 is an example, and the present invention is not limited to this. For example, the common electrode 16 may be directly connected to the connector 44 without using the driving IC 41.

  In FIG. 6, the print medium 70 is conveyed in a continuous state, but the print medium 70 may be composed of a plurality of separated print media. The material of the printing medium 70 is various, such as paper, plastic, film, metal, etc., and it is not necessary to limit the material.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 9 ... Support substrate 9a ... 1st surface 9b ... 2nd surface 9c ... Side surface 9d ... Slope 9e ... 1st corner | angular part 9f ... 2nd corner | angular part 10a ... 1st thermal storage layer 10b ... 2nd thermal storage layer 11 ... Resistor layer 12 ... Conductive layer 13 ... Protective film 14 ... Heat generating resistor 15 ... Individual electrode 16 ... Common electrode 17 ... Connection portion 20 ... Heat sink 30 ... Head substrate 40 ... Circuit substrate 41 ... Drive IC
DESCRIPTION OF SYMBOLS 42 ... Bonding wire 43 ... Protective film 44 ... Connector 50 ... Platen roller 60 ... Conveyance mechanism 61 ... Conveyance medium 70 ... Printing medium 71 ... Ink ribbon 80 ... Control apparatus 90 ... Power supply apparatus 100 ... Thermal print head 200 ... Thermal printer

Claims (5)

A substrate having a first surface facing the printing medium, and an inclined surface having a surface that is continuous with the first surface and is inclined with respect to the first surface;
A first heat storage layer formed so as to cover a corner portion forming a boundary between the first surface and the slope;
A second heat storage layer formed on the first surface;
A heat generating part formed on the first heat storage layer;
An electrode formed on the first heat storage layer and the second heat storage layer and electrically connected to the heat generating portion;
Thermal print head with The first heat storage layer is formed from the first surface of the substrate to above the first virtual surface extending on the slope,
The thermal print head according to claim 1. The first heat storage layer is formed so as not to cover a second corner formed by the side surface of the substrate and the slope.
The thermal print head according to claim 1 or 2. The first heat storage layer and the second heat storage layer are formed separately from each other,
The thermal print head according to any one of claims 1 to 3. The thermal print head according to any one of claims 1 to 4,
A transport mechanism for transporting a printing medium onto a heat generating portion provided in the thermal print head;
A platen roller that presses the printing medium against the heat generating portion;
Thermal printer equipped with.

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