Patent Grant
9061520
The present invention relates to a thermal head and a thermal printer including the same.
Various types of thermal heads have been heretofore proposed as printing devices for a facsimile, a video printer or the like. For example, a thermal head described in Patent Literature 1 includes a substrate, a thermal storage layer disposed on one main surface of the substrate so as to extend to an edge of the substrate, the thermal storage layer being made of glass, electrodes disposed above the thermal storage layer apart from the edge of the substrate, heat-generating resistors connected to the electrodes, a covering layer disposed on the electrodes and the heat-generating resistor and a protection film disposed on the covering layer (for example, refer to Patent Literature 1).
Patent Literature 1: Japanese Unexamined Patent Publication JP-A 2009-131994
In the above thermal head, there is a case where a crack occurs in the thermal storage layer made of glass, and there is a possibility that the crack occurring in the thermal storage layer further extends and penetrates upper and lower surfaces of the thermal storage layer when the thermal head is driven. Accordingly, a chip may occur in the thermal storage layer and the electrodes and the heat-generating resistor may deteriorate.
A thermal head according to an embodiment of the invention includes a substrate; a thermal storage layer disposed on one main surface of the substrate so as to extend to an edge of the substrate, the thermal storage layer being formed of glass; electrodes disposed on or above the thermal storage layer apart from the edge of the substrate; heat-generating resistors disposed above the thermal storage layer apart from the edge of the substrate, the heat-generating resistors being connected to the electrodes; a first covering layer disposed on or above the electrodes and the heat-generating resistors; and a protection film disposed on or above the first covering layer, the first covering layer extending from atop the electrodes and the heat-generating resistors toward atop the thermal storage layer on the edge of the substrate, the protection film being disposed on or above the first covering layer disposed on or above the electrodes and the heat-generating resistors and an edge of the protection film being not disposed above the edge of the substrate.
A thermal printer according to an embodiment of the invention includes the thermal head mentioned above; a conveyance mechanism that conveys a recording medium on a plurality of heat-generating portions; and a platen roller that presses the recording medium on the plurality of heat-generating portions.
According to the invention, possibility of crack extension can be reduced even if any crack occurs in the thermal storage layer.
Hereinafter, a thermal head according to one embodiment of the invention will be described with reference to the drawings. As shown in
The heatsink 1 is made of a metal material such as copper or aluminum, including a bed plate portion 1a having a rectangular shape in a plan view and a protruding portion 1b extending along one long side of the bed plate portion 1a. As shown in
As shown in
The substrate 7 has a rectangular shape, including one main surface, the other main surface arranged on the opposite side of one main surface and a plurality of side surfaces connecting one main surface and the other main surface. An edge 7a of the substrate 7 is formed at a ridgeline portion formed by one main surface and the side surfaces. The substrate 7 is made of an electrically insulating material such as alumina ceramics or a semiconductor material such as monocrystalline silicon.
As shown in
An electric resistor layer 15 is disposed above the upper surface of the thermal storage layer 13. The electric resistor layer 15 is interposed between the thermal storage layer 13 and a later-descried common electrode wiring 17, individual electrode wirings 19, a ground electrode wiring 21 and IC control wirings 23. The electric resistor layer 15 has regions having the same shapes as the individual electrode wirings 19, the common electrode wiring 17, the ground electrode wiring 21 and the IC control wirings 23 in a plan view (hereinafter referred to as interposed regions) as well as a plurality of regions exposed from between the common electrode 17 and the individual electrode wirings 19 as shown in
The respective exposed regions of the electric resistor layer 15 form the heat-generating portions 9. Then, the plurality of heat-generating portions 9 are arranged in a line on the thermal storage layer 13 as shown in
The electric resistor layer 15 is made of a material having relatively high electric resistance such as a TaN-based, a TaSiO-based, a TaSiNO-based, a TiSiO-based, a TiSiCO-based or a NbSiO-based material. Accordingly, when a voltage is applied between the later-described common electrode wiring 17 and the individual electrode wirings 19, and the voltage is applied to the heat-generating portions 9, the heat-generating portions 9 generate heat due to Joule heat.
As shown in
As shown in
The individual electrode wirings 19 extend between the respective heat-generating portions 9 and the driver ICs 11 to connect them to each other as shown in
The main wiring portion 17a of the common electrode wiring 17 is disposed above the thermal storage layer 13 apart from the edge 7a of the substrate 7 as shown in
The ground electrode wiring 21 extends along the arrangement direction of the heat-generating portions 9 in a band shape in the vicinity of the other long side of the substrate 7 as shown in
The driver ICs 11 are arranged so as to correspond to the respective groups of the plurality of heat-generating portions 9 and are connected to one end portions of the individual electrode wirings 19 and the ground electrode wiring 21 as shown in
A plurality of the first connection terminals 11a and the second connection terminals 11b are provided so as to correspond to the respective individual electrode wirings 19, though not shown. The plurality of first connection terminals 11a are individually connected to the respective individual electrode wirings 19. The plurality of second connection terminals 11b are connected to the ground electrode wiring 21 in common.
The IC control wirings 23 are for controlling the driver ICs 11, having IC power wirings 23a and IC signal wirings 23b as shown in
As shown in
As shown in
The end-portion power wiring portion 23aE and the intermediate power wiring portion 23aM are electrically connected to each other inside the driver IC 11 to which both power wiring portions are connected. The adjacent intermediate power wiring portions 23aM are electrically connected to each other inside the driver IC 11 to which both wiring portions are connected.
As described above, the IC power wirings 23a electrically connect between respective driver ICs 11 and the FPC 5 by connecting the IC power wirings 23a to the respective driver ICs 11. Accordingly, electric current is supplied from the FPC 5 to the respective driver ICs 11 through the end-portion power wiring portions 23aE and the intermediate power wiring portions 23aM as described later.
The IC signal wirings 23b include end-portion signal wiring portions 23bE arranged in the vicinity of the right long side of the substrate 7 at both end portions in the longitudinal direction of the substrate 7 and intermediate signal wiring portions 23bM arranged between adjacent driver ICs 11 as shown in
As shown in
The intermediate signal wiring portion 23bM is arranged so that one end portion thereof is arranged at an arrangement region of one of adjacent driver ICs 11 and the other end portion thereof is arranged at an arrangement region of the other of adjacent driver ICs 11 in a manner of being drawn around the intermediate power wiring portion 23aM. The intermediate signal wiring portion 23bM is arranged so that one end portion thereof is connected to one of adjacent driver ICs 11 and the other end portion thereof is connected to the other of adjacent driver ICs 11.
The end-portion signal wiring portion 23bE and the intermediate signal wiring portion 23bM are electrically connected to each other inside the driver IC 11 to which both wiring portions are connected. The adjacent intermediate signal wiring portions 23bM are electrically connected to each other inside the driver IC to which both wiring portions are connected.
As described above, the IC signal wirings 23b electrically connect between the respective driver ICs 11 and the FPC 5 by connecting the IC signal wirings 23b to the respective driver ICs 11. Accordingly, a control signal transmitted from the FPC 5 to the driver IC 11 through the end-portion signal wiring portion 23bE is further transmitted to the adjacent driver IC 11 through the intermediate signal wiring portion 23bM as described later.
The above-described electric resistor layer 15, the common electrode wiring 17, the individual electrode wirings 19, the ground electrode wiring 21 and IC control wirings 23 are formed by, for example, sequentially stacking material layers forming respective components on the thermal storage layer 13 by using, for example, a well-known thin-film forming technique such as sputtering, then, processing a stacked body into a given pattern by using a well-known photolithography technique, an etching technique or the like.
As shown in
The first covering layer 24 is configured to suppress covered portions of the heat-generating portions 9, the common electrode wiring 17 and the individual electrode wirings 19 to be oxidized due to reaction with oxygen or to be corroded due to adhesion of moisture or the like included in the air. The first covering layer 24 is made of a material having a high Vickers hardness value than the thermal storage layer 13, which can be made by materials such as SiN, SiC or SiON. These materials can include other elements such as Al. A Vickers hardness of SiN is approximately 1600 to 1800 HV, a Vickers hardness of SiC is approximately 2000 to 2200 HV and a Vickers hardness of SiON is approximately 1200 to 1400 HV. The first covering layer 24 can be formed by using a well-known thin-film forming technique or the like such as sputtering or vapor deposition. The first covering layer 24 can be formed by stacking a plurality of material layers.
As shown in
The second covering layer 26 is disposed on the first covering layer 24, and an edge 26a of the second covering layer 26 can be disposed on an edge 24a of the first covering layer 24. Accordingly, the possibility that the heat-generating portions 9, the common electrode wiring 17 and the individual electrode wirings 19 are oxidized can be much further reduced.
The second covering layer 26 preferably has a higher Vickers hardness than the first covering layer 24. For example, the first covering layer 24 is made of SiN having the Vickers hardness of approximately 1600 to 1800 HV and the second covering layer 26 is made of SiC having the Vickers hardness of approximately 2000 to 2200 HV, thereby improving abrasion resistance of the second covering layer 26 making contact with a recording medium and obtaining the first covering layer 24 and the second covering layer 26 in which oxidation resistance and abrasion resistance have been improved.
It is also preferable that the second covering layer 26 is made of a material having a lower Vickers hardness than that of the first covering layer 24. For example, the first covering layer 24 is made of SiN having the Vickers hardness of approximately 1600 to 1800 HV and the second covering layer 26 is made of SiON having the Vickers hardness of approximately 1200 to 1400 HV or SiO2 having a Vickers hardness of 600 to 800 HV, thereby alleviating stress by the second covering layer 26 and reducing the possibility that a chip or a crack occurs in the first covering layer 24 and the second covering layer 26 even when large stress is generated in the first covering layer 24 and the second covering layer 26 at the time of separating the thermal head X1 from a mother board, which will be described later in detail.
In particular, when the second covering layer 26 is made of SiO2 having the Vickers hardness of 600 to 800 HV which is softer than the first covering layer 24, adhesiveness with respect to the first protection film 25 can be increased as well as stress generating at the time of separating the substrate is alleviated to thereby obtain the thermal head X1 in which the possibility that a chip or a crack occurs is reduced in the case where the first covering layer 24 is made of SiN having the Vickers hardness of 1600 to 1800 HV. It is not always necessary that the edge of the second covering layer 26 is disposed above the edge 7a of the substrate 7, and it is preferable that the edge of the second covering layer 26 is disposed between the edge 7a of the substrate 7 and the edge 25a of the first protection film 25. Accordingly, the possibility that a crack occurs in the second covering layer 26 can be reduced.
As shown in
The first protection film 25 is disposed on or above the first covering layer 24 over the heat-generating portions 9, the common electrode wiring 17 and the individual electrode wirings 19 as seen from a direction orthogonal to the upper surface of the substrate 7. The edge 25a of the first protection film 25 extends on the first covering layer 24 so as to be positioned between the heat-generating portions 9, the common electrode wiring 17 and the individual electrode wirings 19, and the edge 7a of the substrate 7. In more detail, the first protection film 25 extends on the first covering layer 24 so that the edge 25a of the first protection film 25 is positioned between the main wiring portion 17a of the common electric wiring 17 and the edge 7a of the substrate 7. In the present embodiment, the first protection film 25 corresponds to the protection film in the invention.
As the first protection film 25 is not disposed above the edge 7a of the substrate 7 which is liable to make contact with the outside as described above, the possibility that a crack occurs in the first protection film 25 can be reduced. Accordingly, the heat-generating portions 9, the common electrode wiring 17 and the individual electrode wirings 19 can be sealed with the first protection film 25 even when the crack occurs in the thermal storage layer 13. As a result, the corrosion and deterioration of the heat-generating portions 9, the common electrode wiring 17 and the individual electrode wirings 19 can be reduced.
Here, when the above thermal head is manufactured, there is a case, in general, where the thermal storage layers, electrode wirings, the heat-generating resistors, the protection films or the like to be a plurality of thermal heads are formed at a time on a large mother board from which a plurality of substrates each for forming one thermal head can be taken. When the device is manufactured in the above manner, the thermal storage layer included in the respective thermal heads is formed so as to extend over a plurality of substrates forming a plurality of thermal heads. Accordingly, the thermal storage layer exists on dividing lines of the mother board, namely, on edges of substrates in the respective thermal heads. In such case, a crack may occur in the thermal storage layer arranged on edges of divided substrates when the mother board is divided. Since the crack extends due to thermal response at the time of driving the thermal head, there is a possibility that corrosion or deterioration of the heat-generating resistors 9 occurs when a crack connecting through an upper surface and a lower surface of the thermal storage layer 13 occurs.
In response to the above, the first covering layer 24 extends from atop the main wiring portion 17a of the common electric wiring 17 toward atop the thermal storage layer 13 on the edge 7a of the substrate 7 as seen from the direction orthogonal to the upper surface of the substrate 7, therefore, the thermal storage layer 13 on the edge 7a of the substrate 7 to be a dividing line is covered by the first covering layer 24, for example, even when the edge 7a of the substrate 7 is the dividing line of the mother board as in the related art example. Accordingly, it is possible to reduce the occurrence of a chip or a crack on the thermal storage layer 13 made of glass on the edge 7a of the divided substrate 7 in the case where the mother board is divided as in the related art example.
Furthermore, the occurrence of a crack in the thermal storage layer 13 can be reduced by the first covering layer 24 provided for suppressing oxidation of the heat-generating portions 9, the common electrode wiring 17 and the individual electrode wirings 19, therefore, the structure of the thermal head X1 can be simplified.
The first protection film 25 is configured to protect the heat-generating portions 9, the common electrode wiring 17 and the individual electrode wirings 19 from the abrasion due to the contact to the recording medium to be printed. The first protection film 25 can be made of materials such as glass containing SiO2, Bi2O3 and ZnO, glass containing SiO2, B2O3 and PbO, glass containing SiO2, PbO and ZnO, glass containing SiO2, B2O3 and RO and glass containing SiO2, ZnO and RO or materials such as SiN, SiC or SiON. When the first protection film is made of glass, the Vickers hardness will be 300 to 600 HV.
The first protection film 25 can also be formed by using, for example, a thick-film forming technique such as screen printing, a well-known thin-film forming technique such as sputtering or deposition. In the case where the first protection film 25 is formed by the thick-film forming such as screen printing, a film defect can be filled by the first protection film 25 even when the film defect occurs in a portion of the first covering layer 24 covered by the first protection film 25. The first protection film 25 may be formed by stacking a plurality of material layers.
In the thermal head X1 according to the present embodiment, when the thermal storage layer 13 and the first covering layer 24 disposed above the edge 7a of the substrate 7 provided at corner portions which are liable to collide with exterior components unexpectedly touch a casing of a thermal printer or the like and thus a crack occurs in the thermal storage layer 13 and the first covering layer 24, for example, in the case where the thermal head X1 is assembled to a body of the thermal printer, the possibility of crack extension can be reduced as the first protection film 25 is not disposed above the edge 7a of the substrate.
As described above, the first protection 25 is not disposed above the edge 7a of the substrate 7 to be the dividing line of the mother board. In other words, the possibility that a crack occurs in the first protection film 25 can be reduced even when the substrate 7 is divided at the edge 7a, because the first protection film 25 is disposed apart from the edge 7a of the substrate 7 which is the dividing line. Accordingly, it is possible to reduce the extension of the crack occurring in the thermal storage layer 13 at the same time as the crack occurring in the first protection film 25 extends.
Additionally, as shown in
Furthermore, as the first protection film 25 is not disposed on dividing lines of the mother board, the mother board can be divided while checking the dividing lines. Accordingly, the dividing accuracy in a dividing process of the substrate can be improved.
Moreover, it is preferable that the first protection film 25 has a lower Vickers hardness than that of the thermal storage layer 13. As an exemplification, the first protection film 25 can be made of Pb-based glass or Bi-based glass. Since the first protection film 25 has a lower Vickers hardness than that of the thermal storage layer 13 as described above, the extension of a chip or a crack can be suppressed by the soft first protection film 25 even when the crack occurs in the thermal storage layer 13 and the first covering layer 24.
Though the example in which the edge 25a of the first protection film 25 is vertically provided has been shown in the thermal head X1, the invention is not limited to this. It is also preferable that, for example, the edge 25a has a tapered shape gradually sloping toward the edge 7a of the substrate 7.
As shown in
Additionally, openings (not shown) for exposing end portions of the individual electrode wirings 19 connecting the driver ICs 11, an second intermediate region 21N and a third intermediate region 21L of the ground electrode wiring 21 and end portions of the IC control wirings 23 are formed in the second protection film 28, and these wirings are connected to the driver ICs 11 through the openings. The driver ICs 11 are sealed by being covered with a covering member 29 made of resin such as epoxy resin or silicone resin for protecting the driver ICs 11 themselves and connecting portions between the driver ICs 11 and these wirings in a state of being connected to the individual electrode wirings 19, the ground electrode wiring 21 and the IC control wirings 23.
As shown in
In more detail, in the FPC 5, the respective printed wirings disposed thereinside are connected to end portions of the two sub-wiring portions 17b of the common electric wiring 17, end portions of the ground electrode wiring 21 and end portions of the IC control wirings 23 to thereby connect between these wirings 17, 21 and 23 and the connector 31 by solder bumps 33 (refer to
Moreover, when the connector 31 is electrically connected to the external power supply device, the controller and the like (not shown), the IC power wirings 23a of the IC control wirings 23 are connected to the positive-side terminal of the power supply device held in the positive potential in the same manner as the common electrode wiring 17. Accordingly, electric current for operating the driver ICs 11 is supplied to the driver ICs 11 by the difference of potentials in the IC power wirings 23a to which the driver ICs 11 are connected and the ground electrode wiring 21. The IC signal wirings 23b of the IC control wirings 23 are connected to the controller performing control of the driver ICs 11. Accordingly, a control signal from the controller is transmitted to the driver IC 11 through the end-portion signal wiring portion 23bE, and the control signal transmitted to the driver IC 11 is further transmitted to the adjacent driver IC through the intermediate signal wiring portion 23bM. The on/off states of the switching devices inside the drivers IC 11 are controlled by the control signal, thereby allowing the heat-generating portions 9 to generate heat selectively.
Hereinafter, a manufacturing method of the thermal head X1 will be described.
The manufacturing method of the thermal head X1 includes a process of forming the thermal storage layer 13 over the entire surface of the mother board, a process of forming the electric resistor layer 15 over the entire surface of the thermal storage layer 13, and a process of forming a conductive layer (not shown) to be various types of electrodes such as the common electrode wiring 17 over the entire surface of the electric resistor layer 15. The manufacturing method further includes a process of patterning the electric resistor layer 15 and the conductive layer, a process of forming the first covering layer on the conductive layer other than a portion to be connected to the FPC 5, and a process of forming the first protection film 25 in a given position and firing the film. The first protection film 25 is not disposed on the dividing lines of the mother board. Then, the second protection film 28 is formed in a given position and the mother board is divided along the dividing lines, thereby fabricating the thermal head X1. The process of forming respective component members, the process of performing patterning and the process of dividing can be performed by using any methods generally known in the thin-film or thick-film forming techniques.
The given position where the first protection film 25 is formed differs according to the number of thermal heads X1 to be divided from the mother board. Hereinafter, a case where two thermal heads X1 are divided from the mother board will be described as an example.
When two thermal heads X1 are divided from the mother board, various electrode wirings such as the common electrode wiring are patterned so as to be mirror images to each other with respect to the central line of the mother board. That is, various members are formed by performing patterning so that the dividing line of the substrates 7 will be the central line of the mother board.
Then, the first protection film 25 is formed between the heat-generating portions 9 and the dividing line of the substrates 7. Accordingly, the first protection films 25 which are parallel to each other may be formed to indicate the dividing line of the substrates 7.
As described above, the thermal storage layer 13 and the first covering layer 24 are disposed and the first protection film 25 is not disposed on the dividing line of the substrate 7, and therefore the first covering layer 24 can reduce the possibility that a crack occurring in the thermal storage layer 13 extends even when the substrate 7 is divided at the dividing line. Moreover, as the first protection film 25 is not disposed on the dividing line of the substrate 7, the possibility that a crack occurs in the first protection film 25 can be suppressed.
Next, a thermal printer according to an embodiment of the invention will be described with reference to
As shown in
The conveyance mechanism 40 is configured to convey the recording medium P such as heat-sensitive paper or receiver paper on which ink is transferred in a direction of an arrow S in
The platen roller 50 is configured to press the recording medium P on the heat-generating elements 9 of the thermal head X1, which is arranged so as to extend along a direction orthogonal to the conveying direction S of the recording medium P, both end portions of which are supported so as to be rotated in a state of pressing the recording medium P on the heat-generating elements 9. The platen roller 50 can be formed by, for example, coating a cylindrical shaft 50a made of a metal such as stainless steel with an elastic member 50b made of butadiene rubber or the like.
The power supply device 60 is configured to apply a voltage for allowing the heat-generating elements 9 of the thermal head X1 to generate heat and a voltage for operating the driver ICs 11 as described above. The controller 70 is configured to supply a control signal controlling the operation of the driver ICs 11 to the driver ICs 11 for allowing the heat-generating elements 9 of the thermal head X1 to generate heat selectively as described above.
The thermal printer Z according to the present embodiment can perform given printing on the recording medium P by allowing the heat-generating elements 9 to generate heat selectively by the power supply device 60 and the controller 70 while pressing the recording medium on the heat-generating elements 9 of the thermal head X1 by the platen roller 50 and conveying the recording medium P on the heat-generating elements 9 by the conveyance mechanism 40 as shown in
A thermal head X2 according to a second embodiment will be described with reference to
The thermal head X2 has the second protection film 28 as a resin layer extending from the edge 7a of the substrate 7 onto the first protection film 25. Other portions are the same as those of the thermal head X1, and description thereof is omitted.
In the second protection film 28 disposed above the edge 7a of the substrate 7, one end portion 28b thereof is disposed on the first protection film 25, and the other end portion 28a thereof is disposed above the edge 7a of the substrate 7. Then, a convex portion 30 higher than other portions is disposed on the edge 7a side of the substrate 7. As shown in
The convex portion 30 of the second protection film 28 is located at a higher position than other portions of the second protection film 28. Accordingly, the recording medium, particularly, an ink ribbon having passed on the heat-generating portions 9 is pushed toward a separating direction due to the presence of the convex portion 30 of the second protection film 28. As a result, the separation between the thermal head X2 and the ink ribbon can be smoothly performed. Accordingly, the thermal head X2 capable of performing printing at high speed can be obtained.
As the second protection film 28 is made of soft resin and is disposed above the edge 7a of the substrate 7, the second protection film 28 disposed on the edge 25a of the first protection film 25 can alleviate stress even when the stress generated by the crack extension occurring in the thermal storage layer 13 occurs in the first protection film 25. Accordingly, the possibility that the first protection film 25 separates from the first covering layer 24 can be reduced.
Note that the convex portion 30 of the second protection film 28 is disposed above the edge 7a of the substrate 7. Accordingly, the separation between the thermal head X2 and the ink ribbon can be performed more smoothly.
Hereinafter, a method of forming the second protection film 28 will be described.
The first protection film 25 is formed above the mother board in the same method as the thermal head X1. After that, as shown in
One embodiment of the invention has been described as the above, however, the invention is not limited to the above embodiment and various modifications are possible without departing from the scope of the invention.
For example, though the common electrode wiring 17 and the individual electrode wirings 19 are formed on the electric resistor layer 15 in the thermal head X1 according to the above embodiment as shown in
It is further preferable that the common electrode wiring 17 and the individual electrode wirings 19 are formed on the thermal storage layer 13, and the electric resistor layer 15 is formed only in regions between the common electrode wiring 17 and the individual electrode wirings 19 as shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-013172 | Jan 2011 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2012/051522 | 1/25/2012 | WO | 00 | 7/25/2013 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2012/102298 | 8/2/2012 | WO | A |
| Number | Date | Country |
|---|---|---|
| 2008-230126 | Oct 2008 | JP |
| 2009-131994 | Jun 2009 | JP |
| 2010-247470 | Nov 2010 | JP |
| Entry |
|---|
| Computer-generated translation of JP 2010-247470, published on Nov. 2010. |
| Computer-generated translation of JP 2008-230126, published on Oct. 2008. |
| Computer-generated translation of JP 2009-131994, published on Jun. 2009. |
| Number | Date | Country | |
|---|---|---|---|
| 20130307916 A1 | Nov 2013 | US |
