JP2009166339A - Thermal printing head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal printing head with a near-edge structure capable of performing speedup and making high image quality. <P>SOLUTION: A resistor substrate part 12A and a driving circuit substrate part 12B are arranged on a heat sink 11, and a cooling fin 13 projecting on its end part of the heat sink 11 is formed into an integrated structure with the heat sink 11, and a supporting substrate 15 and a driving circuit substrate 21 are stuck thereon through a heat dissipation adhesive material 14. The cooling fin 13 is thermally brought into contact with the end face 15a of the supporting substrate 15 through the heat dissipation adhesive material 14. A heat emitting resistor layer 17 is formed on a convex glaze layer 16 near the end face 15a, and a first electrode 18a and a second electrode 18b are formed by providing a gap G on its inclined face, and the gap G part is made to be a heat emitting part 19. A protective film 20 is formed by covering the whole face, and a driving IC 22 on the driving circuit substrate 21 is connected with the electrode on a bonding wire W, and is hermetically sealed with a sealing material 23. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermal print head used as an image recording device.

  Thermal print heads have advantages such as low noise and low running cost, and are widely used in recording devices such as barcode printers, weighing machines, digital plate-making machines, video printers, imagers, and seal printers. In general, a thermal print head has a structure in which a support substrate provided with a heat generating portion for image formation, a drive circuit substrate mounted with a drive IC, and the like are arranged on one main surface of a heat sink.

  In particular, there is a so-called near-edge structure thermal print head that facilitates reduction in head dimensions (see, for example, Patent Document 1). This thermal print head usually has a convex glaze layer extending and disposed along a direction (main scanning direction) orthogonal to a direction (sub-scanning direction) in which a recording medium is conveyed on the head. . Then, a heating part is arranged on the opposite side of the driving IC with the top of the convex glaze layer sandwiched so that the driving IC protruding on the driving circuit board surface does not come into contact with the running recording medium. Provided at the edge (near edge) of the support substrate. FIG. 4 is a sectional view in the sub-scanning direction showing an example of this configuration.

  As shown in FIG. 4, in this thermal print head, for example, a resistor substrate portion 102A and a drive circuit substrate portion 102B are provided adjacent to each other on the main surface of the heat sink 101. In the resistor substrate portion 102 </ b> A, the support substrate 104 is attached to the main surface of the heat radiating plate 101 via the heat conductive adhesive layer 103. A convex glaze layer 105 is formed on the edge of the support substrate 104, and the heating resistor layer 106 is formed so as to cover the surface of the convex glaze layer 105 and the surface of the support substrate 104. On the heating resistor layer 106, a first electrode 107a and a second electrode 107b are arranged to face each other with a gap G interposed therebetween. Here, the pair of electrodes 107 including the first electrode 107a and the second electrode 107b are electrically connected to the heating resistor layer 106 in an overlapping manner, and the heating resistor layer 106 exposed in the gap G is formed in the heating part. 108.

  As shown in FIG. 4, the heat generating portion 108 is formed in a region of one slope of the convex glaze layer 105 provided at the near edge of the support substrate 104. Then, the pair of electrodes 107 and the heat generating portion 108 which are energization electrodes of the heat generating portion 108 become one heat generating element, and are arranged in a line as a predetermined number, for example, 2056 heat generating element arrays in the main scanning direction of the thermal print head. . Further, the ends of the pair of electrodes 107 are exposed and are entirely covered with a protective film 109 for bonding wire connection described later.

  On the other hand, the drive circuit board portion 102B is composed of a drive circuit board 110 or the like adhered to the heat sink 101 via an adhesive layer 103, and a circuit pattern (not shown) or the like is formed on the surface of the board, and the drive IC 111 or the like. Is installed. A bonding wire W is used to electrically connect the energizing electrode of the resistor substrate portion 102A and the drive IC 111 of the drive circuit substrate portion 102B and between the drive IC 111 and the circuit pattern of the drive circuit substrate portion 102B. It is connected. These bonding wires W and driving ICs 111 are hermetically sealed with a sealing material 112 made of, for example, an epoxy resin.

  In forming an image on a recording medium using the thermal print head, a thermal recording paper, a thermal transfer ink ribbon, or the like (not shown) is interposed between the protective film 109 and the platen roller 113 in one inclined area of the convex glaze layer 105. And are conveyed at a predetermined speed in the sub-scanning direction. In this conveyance, the heat-sensitive recording medium is heated by the heat generating portion 108 disposed in the one slope area, and the recording medium is printed by the heat.

In such a thermal printing head having a near-edge structure, a convex glaze layer 105 whose cross-sectional shape in the sub-scanning direction on the support substrate 104 is raised into a convex shape having a mountain shape is formed, and a heat generating portion is formed on the convex glaze layer 105. 108 is provided. As described above, when the convex glaze layer 105 has a raised structure, the adhesion of the heat-sensitive recording paper and the thermal transfer ink ribbon to the heat generating portion 108 is improved, and the heat storage property of the heat generating portion 108 is improved and the low heat resistance is reduced. Power consumption can be facilitated. In addition, the size of the support substrate 104 in the sub-scanning direction can be easily reduced.
JP 2005-262828 A

  However, the thermal print head having the near edge structure has a problem that it is difficult to increase the speed and the image quality of a recording apparatus including the thermal print head. In the above speeding up, it is essential to shorten the non-printing time as well as the printing time on the recording medium. Here, the heat storage property of the heat generating portion 108 provided on the upper portion of the convex glaze layer 105 is higher than that in the case where the other glaze layers are thin film type thermal print heads. If this heat storage property is high, the time for heating the heat generating portion 108 to a temperature necessary for printing can be shortened, and the printing time can be shortened. However, on the other hand, if the non-printing time is to be shortened, sufficient heat dissipation of the heat generating portion 108 provided on the convex glaze layer 105 cannot be ensured. If this heat radiation cannot be sufficiently performed, the cut of the printing point is deteriorated, and blurring of image quality in the sub-scanning direction becomes obvious and can be visually recognized.

  By the way, as another thermal print head, a convex glaze layer 105 similar to that described above is provided so as to extend along substantially the center part instead of the edge part of the support substrate 104, and the heat generating part is provided at the top of the head. There is a structure in which 108 is formed. However, the thermal printing head having the near edge structure has poor print point cuts at higher speeds than the thermal printing head in which the heat generating portion is formed on the top of the convex glaze layer.

  As described above, the conventional near-edge thermal print head is suitable for downsizing the head size compared with the other thermal print heads described above, but it is difficult to obtain high heat dissipation, resulting in high speed and high image quality. The structure was difficult to achieve.

  The present invention has been made in view of the above-described circumstances, and has a near-edge thermal structure that enhances heat dissipation due to heat conduction from the heat generating portion on the convex glaze layer to the heat radiating plate, thereby enabling high speed and high image quality. An object is to provide a print head.

  In order to achieve the above object, the thermal print head according to the present invention extends along the edge of the support substrate on the main surface of the support substrate bonded to the heat sink with an adhesive. A glaze layer having a convex cross-sectional shape in a direction perpendicular to the extending direction, a heating resistor layer formed on the surface of the glaze layer or the surface of the support substrate, and the convex glaze layer Between the top of the substrate and the edge of the support substrate, the electrode formed by providing a gap on the heating resistor layer on the inclined surface of the glaze layer, and the electrode exposed in the gap portion of the electrode Covering at least the heat generating portion of the heat generating resistor layer, a protective film laminated on the glaze layer and the support substrate, protruding on the heat radiating plate, an end surface of the edge portion of the support substrate and a heat radiating adhesive Cooling fins in thermal contact with Has, the cooling fins, to dissipate heat generated by the heating unit together with the heat radiating plate has a structure.

  According to the configuration of the present invention, it is possible to provide a thermal print head in which heat dissipation by heat conduction from the heat generating portion on the convex glaze layer to the heat radiating plate is enhanced, and the speed and image quality can be improved.

  An embodiment of the present invention will be described with reference to FIG. 1, FIG. 2, and FIG. Here, FIG. 1 is a top view showing an example of a thermal print head, and FIG. 2 is an enlarged cross-sectional view taken along the line XX of FIG. And FIG. 3 shows the modification of this embodiment, and becomes an expanded horizontal sectional view of the XX arrow of FIG. Hereinafter, the same or similar parts are denoted by common reference numerals, and redundant description is omitted. However, the drawings are schematic and ratios of dimensions and the like are different from actual ones.

As shown in FIGS. 1 and 2, in the thermal print head 10, the resistor substrate portion 12 </ b> A and the drive circuit substrate portion 12 </ b> B are provided adjacent to each other on the main surface of the heat radiating plate 11. Here, the cooling fins 13 protruding at the end of the heat radiating plate 11 are formed in an integral structure. In the resistor substrate portion 12A, a support substrate 15 having good heat resistance and heat conductivity, such as Al ₂ O ₃ (alumina), is attached to the main surface of the heat radiating plate 11 via a heat radiating adhesive 14. Has been. Further, the end surface 15 a of the support substrate 15 is in thermal contact with the cooling fin 13 through the heat dissipating adhesive 14.

  A convex glaze layer 16 having a mountain-shaped cross-sectional shape in the sub-scanning direction, which is one direction, is disposed in the main scanning direction along the edge near the end surface 15a on the support substrate 15, and this convex glaze. A heating resistor layer 17 is formed on the surface of the layer 16 and the surface of the support substrate 15.

  Then, as described in the prior art, the first electrode 18a and the second electrode 18b that overlap and are electrically connected to the heating resistor layer 17 are arranged to face each other with the gap G interposed therebetween. The heating resistor layer 17 exposed in the gap G becomes the heating portion 19. As described above, the heat generating portion 19 is formed on the inclined surface between the end surface 15a of the support substrate 15 on the side close to the top of the convex glaze layer 16 having a convex cross-sectional shape. The Then, with a pair of electrodes 18 including the first electrode 18a and the second electrode 18b and the heat generating portion 19 as one heat generating element, a predetermined number, for example, 2056 heat generating element arrays are arranged in a row in the main scanning direction of the thermal print head. Placed in. And the edge part of a pair of electrode 18 is exposed for the bonding wire connection mentioned later, and the whole is coat | covered with the protective film 20 with good heat conductivity.

  The drive circuit board portion 12B has a drive circuit board 21 adhered to the heat radiating plate 11 with a heat radiating adhesive 14 as described in the prior art, and a circuit pattern or the like is formed on the surface of the board. The drive IC 22 and the like are mounted. The driving IC 22 and the pair of electrodes 18 and the circuit pattern are electrically connected by a bonding wire W, and the bonding wire W and the driving IC 22 are hermetically sealed by a sealing material 23 made of, for example, epoxy resin. . The driving IC 22 may be mounted on the resistance substrate portion 12A via an insulating material.

  As described above, the thermal print head 10 includes the convex glaze layer 16 in which the heat generating portion 19 of the heat generating element is an end portion of the resistor substrate portion 12A and the cross-sectional shape in one direction of the support substrate 15 is raised in a mountain shape. A so-called near-edge structure is formed on the slope and the drive IC 22 is disposed on the opposite side across the top of the glaze layer 16. In the near-edge structure thermal print head 10, the upper end surface 13 a of the cooling fin 13 is positioned so as not to contact the recording medium that is pressure-fed by the platen roller over the heat generating portion 19. And the cross-sectional width in the sub scanning direction which is one direction of the cooling fin 13 will be about 0.3 mm-1 mm, for example.

Moreover, the heat sink 11 and the cooling fin 13 are made of a metal material such as Al (aluminum), for example, and the heat-dissipating adhesive 14 is a double-sided tape having a good thermal conductivity and a silicone type having a thickness of about 0.1 mm or less It consists of an insulating adhesive such as gel material or epoxy resin. Here, as the heat dissipating adhesive material 14, a material having a high heat conductivity mixed with a normal heat conductive resin is particularly suitable. Examples of the filler having high thermal conductivity include those in which ceramics such as Al ₂ O ₃ , AlN (aluminum nitride), SiC (silicon carbide), and Si ₃ N ₄ (silicon nitride) are finely divided. Here, the particle diameter of the fine particles is preferably 10 μm to 100 μm, and the content thereof is determined by the kind of fine particles to be mixed or the heat radiation amount. % To 90 vol. % Is appropriately set.

By mixing such a high thermal conductivity filler, a typical thermal conductivity of 0.2 W / m · K weak epoxy resin, for example, 80vol the Al ₂ O ₃ fine particles of the filler. When it is contained in about%, it has a thermal conductivity of about 20 W / m · K. Here, in the case of the heat dissipating adhesive material 14 in which a filler made of AlN fine particles is mixed instead of the Al ₂ O ₃ fine particles, the thermal conductivity is about 100 W / m · K.

The ceramic support substrate 15 is usually a support substrate made of an insulating material having heat resistance, and may be made of Si (silicon), quartz, SiC or the like in addition to Al ₂ O ₃ ceramics. .

The convex glaze layer 16 may be any insulator material that has an action of accumulating and dissipating heat generated by the heat generating portion 19 and having surface smoothness. For example, it is made of a glass film made of SiO ₂ (silicon oxide) or a low thermal conductive material such as polyimide resin.

  The heating resistor layer 17 is made of, for example, a TaSiO, NbSiO, TaSiNO, or TiSiCO based electrical resistor material. An electrode such as a pair of electrodes made up of the first electrode 18a and the second electrode 18b and serving as a current-carrying electrode is preferably as low as possible. For example, a metal such as Al, Cu (copper) or an AlCu alloy is mainly used. Composed of materials.

The protective film 20 is made of a hard and dense insulating material such as Si ₃ N ₄ , SiON (silicon oxynitride) or SiC. Here, when at least Si and carbon (C) are contained in the outermost surface of the protective film 20, the thermal conductivity is increased, which is preferable. The protective film 20 covers the pair of electrodes 18 and the heat generating portion 19 of the heat generating element array and has a function of protecting the recording medium from abrasion due to pressure contact or sliding contact, and corrosion due to contact with moisture contained in the atmosphere. Have.

Next, a method for manufacturing the thermal print head 10 will be described. First, an elongated support substrate 15 made of Al ₂ O ₃ ceramic and having a width in the sub-scanning direction of about 3 mm and a plate thickness of 0.5 mm to 1 mm is prepared. Then, in the vicinity of the edge of the main surface, along the main scanning direction, for example, a glass paste obtained by adding and mixing a suitable organic solvent and solvent to the glass powder of SiO ₂ is applied by a well-known screen printing method. Form. Thereafter, firing is performed at a predetermined temperature, and the convex glaze layer 16 whose cross-sectional shape is mountain-shaped and whose top height is, for example, 10 μm to 100 μm and whose width in the sub-scanning direction is, for example, 100 μm to 500 μm is formed on the surface of the support substrate 15 Adhere to. In addition, the convex glaze layer 16 may be a polyimide resin or the like.

Next, a TaSiO ₂ film having a film thickness of about 0.05 μm is formed on the surface of the convex glaze layer 16 and the surface of the support substrate 15 by, for example, a sputtering method, and the heating resistor layer 17 is formed by a photoengraving process. To do. Subsequently, the heating resistor layer 17 is coated by sputtering to form an Al film or an AlCu alloy film having a film thickness of, for example, about 0.5 μm, and an energization electrode of the heating element array is formed by a photoengraving process. The first electrode 18a and the second electrode 18b are formed by patterning. Here, the heating resistor layer 17, the first electrode 18a, and the second electrode 18b may be formed in the same pattern by one photoengraving process.

Thereafter, a protective film 20 that covers the entire surface is formed by sputtering. Here, the protective film 20 may be formed, for example, on a Si ₃ N ₄ film or a SiON film, such as a SiC film having a high thermal conductivity with a film thickness of about 2 μm to 5 μm.

  Next, the resistor substrate portion 12A and the drive circuit substrate portion 12B in which, for example, a bare chip drive IC 22 is incorporated in advance are pressed and fixed onto the heat radiating plate 11 made of an Al plate or the like via the heat radiating adhesive 14. At this time, the cooling fin 13 is also adhered and fixed to the end surface 15 a of the support substrate 15 by the heat dissipating adhesive 14.

  Then, all the energization electrodes of the heating element array are electrically connected to the bonding pads on the output side of the drive IC 22 by bonding wires W made of, for example, Al wires or Au wires. Further, the bonding pad on the input side of the driving IC 22 is electrically connected to the circuit pattern of the driving circuit board 21 by the bonding wire W. Finally, the driving IC 22 and the bonding wire W are hermetically sealed with the sealing material 23 by a known mounting technique. Thus, the thermal print head 10 of this embodiment is completed.

  Next, in the modified example shown in FIG. 3 of the present embodiment, the upper end surface 13b of the cooling fin 13 integrally formed with the heat radiating plate 11 is an inclined surface, and the recording medium that is pressure-fed by the platen roller over the heat generating portion 19 contacts. It is supposed not to. Here, when the recording medium is made of a hard material such as a card or an optical disk, the angle of the inclined surface is preferably matched with the inclination angle of the straight path 24 that is a passage path through which the recording medium is pumped. As a result, the allowable height of the cooling fin 13 to protrude from the case described with reference to FIG. 2 is increased, and accordingly, the height position of the heat dissipating adhesive material 14 between the end surface 15a of the support substrate 15 is set. Can be up. For example, the heat-dissipating adhesive 14 is increased to a height at which it contacts the convex glaze layer 16 or the heating resistor layer 17 as shown in FIG.

  For this reason, the heat radiation effect by the cooling fin 13 of the heat | fever emitted from the heat-emitting part 19 comes to increase rather than the case shown in FIG. Here, the inclination angle of the straight path 24 is normally about 3 to 12 ° from the main surface of the support substrate 15, and the inclination angle of the upper end surface 13b is also about the same.

  In the thermal print head 10 of the present embodiment, the convex glaze layer 16 is provided on the edge portion on one main surface of the support substrate 15, and the heat generating portion 19 of the heat generating element array is formed on one inclined surface of the convex glaze layer 16. The near edge structure is formed. And the cooling fin 13 which protruded on the heat sink 11 is formed so that it may contact thermally with the end surface of the said edge part via the heat dissipation adhesive material 14. FIG. For this reason, the heat generated by the heat generating part 19 is easily absorbed by the heat conduction to the cooling fins 13 adjacent to the heat generating part 19. The absorbed heat is diffused throughout the radiator plate 11. Further, the heat generated from the heat generating portion 19 is thermally conducted to the heat radiating plate 11 through the heat radiating adhesive 14 on the bottom surface of the support substrate 15 and is radiated. In this way, the heat generated in the heating element array can be controlled to be dissipated through the heat radiating plate 11 with extremely high efficiency.

  In addition, it is possible to achieve high speed and high image quality in a recording device including the thermal print head of the present embodiment. Further, since the thermal print head has a near-edge structure, the size of the support substrate 15 in the sub-scanning direction is reduced, and the substrate cost can be reduced and the thermal print head can be easily downsized.

  Although the preferred embodiments of the present invention have been described above, the above-described embodiments do not limit the present invention. Those skilled in the art can make various modifications and changes in specific embodiments without departing from the technical idea and technical scope of the present invention.

  For example, unlike the present embodiment, the cooling fin 13 may not be an integral structure with the heat radiating plate 11 but may be formed of a member having high thermal conductivity that is thermally connected to the heat radiating plate 11.

  The cooling fin 13 may be in thermal contact with the end surface 15a of the support substrate 15 by a heat dissipating adhesive different from the case where the bottom surface of the support substrate 15 is attached to the heat dissipation plate 11.

  The main surface of the support substrate 15 may have only a convex glaze layer 16, or may be a glaze layer having a glaze layer on the entire support substrate and having a convex shape.

  The drive circuit board portion 12B may be formed on the same support substrate 15 as the resistor substrate portion 12A. Further, the drive circuit board portion 12B may be arranged at a location different from the thermal print head. For example, it may be attached to the control device of the recording device, and for example, the output of the drive IC 22 may be transmitted to the resistor substrate portion 12A through the circuit wiring of the flexible wiring board.

  Further, the support substrate 15 and the drive circuit substrate 21 may be attached to the heat radiating plate 11 using different adhesive materials. This is preferable for preventing breakage due to cracks when the support substrate 15 and the drive circuit substrate 21 have different thermal expansion coefficients.

FIG. 3 is a top view illustrating an example of a thermal print head according to an embodiment of the present invention. The expanded cross-sectional view of the XX arrow of FIG. The expanded cross-sectional view of the XX arrow of FIG. 1 which showed the modification of embodiment of this invention. Sectional drawing which shows the thermal print head concerning the prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Thermal print head, 11 ... Heat sink, 12A ... Resistor board | substrate part, 12B ... Drive circuit board part, 13 ... Cooling fin, 13a, 13b ... Upper end surface, 14 ... Heat radiation adhesive, 15 ... Support board, 15a DESCRIPTION OF SYMBOLS ... End face, 16 ... Convex glaze layer, 17 ... Heating resistor layer, 18a ... 1st electrode, 18b ... 2nd electrode, 19 ... Heat generating part, 20 ... Protective film, 21 ... Drive circuit board, 22 ... Drive IC, 23 ... Sealing material, 24 ... Straight pass, G ... Gap, W ... Bonding wire

Claims (3)

On the main surface of the support substrate attached to the heat sink with an adhesive, the cross-sectional shape in the direction orthogonal to the extending direction is disposed along the edge of the support substrate. A convex glaze layer,
A heating resistor layer formed on the surface of the glaze layer or the surface of the support substrate;
An electrode formed between the top of the convex glaze layer and the edge of the support substrate, with a gap provided on the heating resistor layer on the inclined surface of the glaze layer;
A protective film that covers at least the heat generating portion of the heating resistor layer exposed in the gap portion of the electrode, and is laminated on the glaze layer and the support substrate;
A cooling fin that protrudes on the heat radiating plate and is in thermal contact with the end surface of the edge portion of the support substrate through a heat dissipating adhesive;
The cooling fin radiates heat generated by the heat generating portion together with the heat radiating plate.   The thermal print head according to claim 1, wherein the cooling fin is formed integrally with the heat radiating plate.   3. The thermal print according to claim 1, wherein an upper end surface of the cooling fin has a height position or an inclined surface that does not hinder the running of the recording medium that is pressure-fed over the heat generating portion. head.

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