Patent Application
20130328988
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 and so on. For example, a thermal head described in Patent Literature 1 includes a substrate, a plurality of heat-generating portions disposed on or above the substrate and electrodes connected to the plurality of heat-generating portions. The plurality of heat-generating portions and the electrodes are covered by a protective film, and a conductive layer is further formed over the protective film. Then, part of the conductive layer contacts the electrodes. Accordingly, static electricity generated in a medium on which printing is performed can be relieved to the electrodes through the conductive layer on the protective film in the thermal head described in Patent Literature 1.
Patent Literature 1: Japanese Unexamined Patent Publication JP-A 2006-181822
However, as the medium is carried while contacting the conductive layer positioned on the heat-generating portions at the time of printing in the thermal head described in Patent Literature 1, there is a problem that the conductive layer is abraded and the protective film on the heat-generating portions is exposed. When the conductive layer is abraded in this manner, there is a possibility that the medium does not contact the conductive layer and the protective film exposed on the heat-generating portions is dielectrically broken down due to static electricity accumulated in the medium to thereby damage the heat-generating portions.
A thermal head according to an embodiment of the invention includes a substrate, a plurality of heat-generating portions disposed on or above the substrate, electrodes provided on or above the substrate and electrically connected to the plurality of heat-generating portions and a protective layer provided along an arrangement direction of the plurality of heat-generating portions, the protective layer covering the plurality of heat-generating portions and the electrodes. Moreover, the protective layer has an electrical insulating layer covering the plurality of heat-generating portions and the electrodes, a conductive layer provided on the electrical insulating layer, and an abrasion resistance layer provided on the conductive layer. Furthermore, part of the conductive layer is an exposed portion exposed from the abrasion resistance layer.
According to the invention, it is possible to provide a thermal head and a thermal printer including the same capable of reducing abrasion of the conductive layer and reducing damage of the heat-generating portions.
Hereinafter, a thermal head according to an embodiment of the invention will be explained with reference to the drawings. As shown in
The heat dissipating member 1 is made of, for example, a metal material such as copper or aluminum, including a bedplate portion la having a rectangular shape and a protruding portion 1b extending along one long side of the bedplate portion 1a. As shown in
As shown in
The substrate 7 is made of an electric insulating material such as alumina ceramics, a semiconductor material such as monocrystalline silicon.
As shown in
The thermal storage layer 13 can be made of, for example, glass having low thermal conductivity and temporarily accumulates part of heat generated in the heat-generating portions 9. Accordingly, the thermal storage layer 13 functions so as to shorten the time necessary for increasing the temperature of the heat-generating portions 9 and so as to increase thermal response characteristics of the thermal head X1. The glass for forming the thermal storage layer 13 is formed by, for example, applying a predetermined glass paste obtained by mixing a suitable organic solvent into glass powder by using a well-known screen printing or the like and filing the resultant at a high temperature.
Examples of the glass for forming the thermal storage layer 13 include glass containing SiO2, Al2O3, CaO and BaO, glass containing SiO2, Al2O3 and PbO, glass containing SiO2, Al2O3 and BaO, and glass containing SiO2, B2O3, PbO, Al2O3, CaO and MgO.
An electric resistor layer 15 is provided on an 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 17, individual electrodes 19, a ground electrode 21 and IC-control electrodes 23. The electric resistor layer 15 has regions having the same shapes of these individual electrodes 19, the common electrode 17, the ground electrode 21 and the IC-control electrodes 23 in a plan view as shown in
The respective exposed regions of the electric resistor layer 15 form the heat-generating portions 9. The plurality of heat-generating portions 9 are arranged in a line on the raised portion 13b of 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 common electrode 17 and the individual electrodes 19, and electric current is supplied to the heat-generating portions 9, the heat-generating portions 9 generate heat due to Joule heat.
As shown in
The common electrode 17 has a main wiring portion 17a, sub-wiring portions 17b and lead portions 17c as shown in
The individual electrodes 19 extend to between the respective heat-generating portions 9 and the driver ICs 11, electrically connecting respective heat-generating portions 9 to the driver ICs 11 as shown in
The ground electrode 21 extends along the arrangement direction in the vicinity of the other long side 7b of the substrate 7 in a band shape as shown in
The driver IC 11 is connected to a second intermediate region 21N positioned between the end region 21E and the first intermediate region 21M of the ground electrode 21. The driver IC 11 is also connected to a third intermediate region 21L positioned between adjacent first intermediate regions 21M. Accordingly, the driver ICs 11 and the FPC 5 are electrically connected.
The driver ICs 11 are disposed 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 electrodes 19 and the ground electrode 21 as shown in
A plurality of first connection terminals 11a connected to the individual electrodes 19 and a plurality of second connection terminals 11b connected to the ground electrode 21 are provided so as to correspond to the respective individual electrodes 19, though not shown. The plurality of first connection terminals 11a are individually connected to respective individual electrodes 19. The plurality of second connection terminals 11b are connected to the ground electrode 21 in common.
The IC control electrodes 23 are provided for controlling the driver ICs 11, having IC power electrodes 23a and IC signal electrodes 23b as shown in
As shown in
As shown in
The end-portion power electrode portion 23aE and the intermediate power electrode portion 23aM are electrically connected to each other inside the driver IC 11 to which both portions are connected. The adjacent end-portion power electrode portions 23aM are electrically connected to each other inside the driver IC 11 to which both portions are connected.
As described above, the IC power electrodes 23a electrically connect between respective driver ICs 11 and the FPC 5 by connecting the IC power electrodes 23a to respective driver ICs 11. Accordingly, the thermal head X1 supplies electric current from the FPC 5 to the respective driver ICs 11 through the end-portion power electrode portions 23aE and the intermediate power electrode portions 23aM as described later.
The IC signal electrodes 23b include end-portion signal electrode portions 23bE and intermediate signal electrode portions 23bM as shown in
As shown in
The intermediate signal electrode portion 23bM is disposed so that one end portion is arranged at an arrangement region of one of adjacent driver ICs 11 and the other end portion is arranged at an arrangement region of the other of adjacent driver ICs 11 in a manner of being drawn around the intermediate power electrode portion 23aM. The intermediate signal electrode portion 23bM is disposed so that one end portion is connected to one of adjacent driver ICs 11 and the other end portion is connected to the other of adjacent driver ICs 11.
The end-portion signal electrode portion 23bE and the intermediate signal electrode portion 23bM are electrically connected to each other inside the driver IC 11 to which both portions are connected. The adjacent end-portion signal electrode portions 23bM are electrically connected to each other inside the driver IC 11 to which both portions are connected.
As described above, the IC signal electrodes 23b electrically connect between the respective driver ICs 11 and the FPC 5 by connecting the IC signal electrodes 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 electrode portion 23bE is further transmitted to the adjacent driver IC 11 through the intermediate signal electrode portion 23bM as described later.
The above-described electric resistor layer 15, the common electrode 17, the individual electrodes 19, the ground electrode 21 and IC-control electrodes 23 are formed by, for example, sequentially stacking material layers forming the 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 predetermined pattern by using a well-known photolithography technique, an etching technique or the like.
As shown in
In more detail, the first protective layer 25 includes an electrical insulating layer 25a formed on the thermal storage layer 13, a conductive layer 25b formed on the electrical insulating layer 25a and an abrasion resistance layer 25c formed on the conductive layer 25b as shown in
The electrical insulating layer 25a covers the heat-generating portions 9 formed on the thermal storage layer 13 and also covers the common electrode 17 and the individual electrodes 19 connected to the heat-generating portions 9 though not shown in
The conductive layer 25b is provided over the whole surface of the electrical insulating layer 25a, and the abrasion resistance layer 25c is provided on the conductive layer 25b. Then, part of the conductive layer 25b is exposed portions 25bh exposed from the abrasion resistance layer 25c. In the thermal head X1, the exposed portions 25bh are formed by the conductive layer 25b exposed from openings 25ch provided in the abrasion resistance layer 25c.
As shown in
The exposed portions 25bh are provided on a line extended from a row composed of the plurality of heat-generating portions 9 at portions positioned at both end portions in the arrangement direction in a plan view of the thermal head X1. An outside shape of the opening 25ch and the exposed portion 25bn is a triangular shape in a plan view. Here, as a general idea, the triangular shape is not limited to a shape formed by connecting three points respectively by segments but includes a shape in which corner portions connecting sides forming the triangle are rounded.
The triangular shape of the exposed portions 25bh is preferably an isosceles triangle extending toward the outside of the arrangement direction as shown in
Then, the conductive layer 25b is electrically connected to the ground electrode 21 via through holes (not shown) provided in the electrical insulating layer 25a and is held in a ground potential. It is also preferable that the conductive layer 25b is electrically connected to the common electrode 17, not the ground electrode 21. According to the above structure, static electricity relieved from the medium to the conductive layer 25b can be discharged more positively. It is also preferable that the electrical insulating layer 25a positioned on the common electrode 17 or the individual electrodes 19 is partially removed by exposure or by forming notches to be electrically connected, not via through holes.
The conductive layer 25b is made of a material having conductivity, which can be made of, for example materials such as TaSiO, Al and Cu. When the conductive layer 25b is made of TaSiO, the specific resistance will be 2.3×10−5 (Ω·m), when the conductive layer 25b is made of Al, the specific resistance will be 2.65×10−8 (Ω·m), and when the conductive layer 25b is made of Cu, the specific resistance will be 1.68×10−8 (Ω·m). It is also preferable to form the conductive layer 25b by Ag or Au.
Accordingly, when the medium on which printing is performed contacts the exposed portion 25bh as described later, static electricity accumulated in the medium can be relieved to the conductive layer 25b held in the ground potential or the positive potential. Accordingly, it is possible to reduce dielectric breakdown of the protective film 25c on the heat-generating portions 9 and to reduce damage of the heat-generating portions 9.
The abrasion resistance layer 25c is made of a material having higher abrasion resistance than the conductive layer 25b, which can be made of, for example, SiC, Si3N4 and so on. When the abrasion resistance layer 25c is made of SiC, Vickers hardness will be 2000 to 2200 Hv, and when the abrasion resistance layer 25c is made of Si3N4, Vickers hardness will be 1600 to 1800 Hv. The abrasion resistance layer 25c has higher abrasion resistance as described above, therefore, the abrasion of the entire protective film 25 can be suppressed as well as abrasion of the conductive layer 25b interposed between the electrical insulating layer 25a and the abrasion resistance layer 25c can be suppressed. As the abrasion resistance layer 25c is formed on the conductive layer 25b of the protective film 25 as described above, it is possible to reduce abrasion of the conductive layer 25b. Accordingly, the abrasion of the conductive layer 25b can be reduced as well as damage of the heat-generating portions 9 can be reduced when applying the thermal head X1 according to the embodiment.
Additionally, the abrasion resistance layer 25c has the opening 25ch, and part of the conductive layer 25b exposed from the opening 25ch is the exposed portion 25bh, therefore, it is possible to reduce the possibility that the periphery of the exposed portion 25b is abraded. Furthermore, as the abrasion resistance layer 25c is provided so as to surround the exposed portion 25bh, it is possible to reduce the possibility that the exposed portion 25bh contacts the medium frequently and to reduce the abrasion of the exposed portion 25bh. Also in the case where the exposed portion 25bh is provided so as to be surrounded by the abrasion resistance layer 25c as described above, static electricity accumulated in the medium can be discharged and damage of the heat-generating portions 9 can be reduced when the exposed portion 25bh contacts the medium at a predetermined frequency during printing of the thermal head X1.
The abrasion resistance layer 25c has the openings 25ch on the line extended from the row composed of the plurality of heat-generating portions 9 and part thereof is the exposed portions 25bh in which the conductive layer 25b is exposed from the openings 25ch as shown in
Additionally, the openings 25ch of the abrasion resistance layer 25c are formed on both end portions of the raised portion 13b of the thermal storage layer 13 extending along the arrangement direction of the plurality of heat-generating portions 9. When the openings 25ch are disposed in this manner, the medium is allowed to contact the conductive layer 25b easily. That is, the raised portion 13b of the thermal storage layer 13 extends along the arrangement direction of the heat-generating portions 9 in the present embodiment. Accordingly, for example, when the medium is pressed onto the plurality of heat-generating portions 9 by the platen roller, the medium is pressed with greater force on both end portions than on the center portion of the raised portion 13b in which the heat-generating portions 9 are arranged. Accordingly, the medium is allowed to contact the exposed portions 25bh of the conductive layer 25b exposed from the openings 25ch.
When the electrical insulating layer 25a, the conductive layer 25b and the abrasion resistance layer 25c are formed as the first protective layer 25 by sequentially stacking these components in this order, it is possible to reduce the possibility that the covered heat-generating portions 9, part of the common electrode 17 and the individual electrodes 19 are oxidized due to reaction with oxygen or to reduce the possibility that these portions are corroded due to adhesion of moisture included in the air and the like. The electrical insulating layer 25a, the conductive layer 25b and the abrasion resistance layer 25c forming the first protective layer 25 can be formed by a well-known thin-film forming technique such as sputtering or deposition, or by using a thick-film forming technique such as screen printing. Additionally, the openings 25ch of the abrasion resistance layer 25c can be formed by, for example, polishing the abrasion resistance layer 25c from the surface to thereby punch holes.
Furthermore, the openings 25ch in the abrasion resistance layer 25c are formed on both end portions of the raised portion 13b of the thermal storage layer 13 extending along the arrangement direction. Accordingly, as the medium is pressed by the platen roller with great force on both end portions of the raised portion 13b as described above, the medium is allowed to contact the conductive layer 25b exposed from the openings 25ch easily. Consequently, static electricity generated in the medium can be positively relieved by the conductive layer 25b.
Moreover, as the exposed portions 25b are formed on both end portions of the raised portion 13b in the arrangement direction, the possibility that the exposed portions 25b contacts the medium can be increased and static electricity accumulated in the medium can be relieved through the conductive layer 25b.
Furthermore, the openings 25ch of the abrasion resistance layer 25c are formed on both end portions of the raised portion 13b of the thermal storage layer 13 extending along the arrangement direction of the plurality of heat-generating portions 9. Accordingly, as the medium is pressed by the platen roller with great force on both end portions of the raised portion 13b as described above, the recording medium is allowed to contact the conductive layer 25b exposed from the openings 25ch easily. Consequently, static electricity generated in the medium can be positively relieved by the conductive layer 25b.
As shown in
Additionally, openings (not shown) for exposing end portions of the individual electrodes 19 connecting the driver ICs 11, the second intermediate regions 21N and the third intermediate region 21L of the ground electrode 21 as well as end portions of the IC control electrodes 23 are formed in the second protective film 27, 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 electrodes 19, the ground electrode 21 and the IC-control electrodes 23.
As shown in
In more detail, in the FPC 5, the respective printed wirings formed thereinside are respectively connected to end portions of the sub-wiring portions 17b of the common electrode 17, end portions of the ground electrode 21 and end portions of the IC-control electrodes 23 by solder 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 electrodes 23a of the IC control electrodes 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 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 electrodes 23a to which the driver ICs 11 are connected and the ground electrode 21. The IC signal electrodes 23b of the IC control electrodes 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 electrode portion 23bE, and the control signal transmitted to the driver IC 11 is further transmitted to the adjacent driver IC 11 through the intermediate signal electrode portion 23bM. The on/off states of the switching devices inside the driver ICs 11 are controlled by the control signal, thereby allowing the heat-generating portions 9 to generate heat selectively.
Next, a thermal printer according to an embodiment of the invention will be explained with reference to
As shown in
The conveyance mechanism 40 is provided for conveying the medium P such as heat-sensitive paper and receiver paper on which ink is transferred in a direction of an arrow S in
The platen roller 50 is provided for pressing the medium P on the heat-generating portions 9 of the thermal head X1, which is disposed so as to extend along a direction orthogonal to the conveying direction S of the medium P, both end portions of which are supported so as to be rotated in a state of pressing the medium P on the heat-generating portions 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.
In the present embodiment, the width of the medium P is wider than a length of the raised portion 13b of the thermal storage layer 13 in the thermal head X1. Additionally, a length of the platen roller 50 is longer than the length of the raised portion 13 of the thermal storage layer 13 in the thermal head X1. Accordingly, it is possible to press the medium P onto the exposed portions 25bh exposed from the openings 25ch of the abrasion resistance layer 25c positioned on both end portions of the raised portion 13b while pressing the medium P on the heat-generating portions 9 disposed on the raised portion 13b.
The power supply device 60 is provided for supplying electric current for allowing the heat-generating portions 9 of the thermal head X1 to generate heat and electric current for operating the driver ICs 11 as described above. The controller 70 is provided for supplying a control signal controlling the operation of the driver ICs 11 to the driver ICs 11 for allowing the heat-generating portions 9 of the thermal head X1 to generate heat selectively as described above.
The thermal printer Z according to the present embodiment can perform predetermined printing on the medium P by allowing the heat-generating portions 9 to generate heat selectively by the power supply device 60 and the controller 70 while pressing the medium P on the heat-generating portions 9 of the thermal head X1 by the platen roller 50 and conveying the medium P on the heat-generating portions 9 by the conveyance mechanism 40 as shown in
A method of driving the thermal printer Z will be explained by using
The thermal printer Z includes the thermal head X1, the power supply device 60, the controller 70 and a measuring device 90. Then, the controller 70 informs outside of whether the thermal printer Z can be actuated or not based on an area value measured by the measuring device 90 at the time of starting driving of the thermal printer Z.
The controller 70 includes a control unit 72, an informing unit 74 and a comparing unit 76. The control unit 72 has a function of performing control of the thermal printer Z, which can apply, for example, a microcomputer mainly including a CPU, a ROM, a RAM and an input/output interface.
The informing unit 74 has a function of informing outside of whether the thermal printer Z can be actuated or not, displaying whether actuation can be performed or not on a display device (not shown) provided outside the thermal printer Z based on a signal transmitted by the control unit 72.
The comparing unit 76 compares a limit area value as a predetermined value which is stored in advance with a measured area value transmitted by the measuring unit, determining whether the measured area value exceeds the limit area value or not.
The measuring device 90 includes a measuring unit 92 measuring the area of the exposed portion 25bh and an imaging unit 94 taking an image of the exposed portion 25bh. As the measuring device 90, a camera module imaging the exposed portion 25bh can be exemplified. The measuring unit 92 calculates a measured area value by performing image processing of the image taken by the imaging unit 94.
The measuring device 90 is disposed above the thermal head X1 for taking the image of the exposed portion 25bh, which images the exposed portion 25bh from above by the imaging unit 94 to thereby calculate the measured area value. It is also preferable that the measuring device 90 is provided in a lateral direction and imaging is performed from the lateral direction.
Here, the limit area value used as the predetermined value stored in the comparing unit 76 will be explained.
The limit area value functions as a parameter indicating a degree of abrasion of the first protective film 25, which is a parameter different according to the medium P. These limit area values can be calculated by experiments or simulations.
The method of driving the thermal printer Z will be explained with reference to
The thermal printer Z starts driving when information of the medium P and a signal indicating the start of driving are supplied from the outside. The control unit 72 transmits the signal indicating the start of driving to the measuring unit 92 based on the signal indicating the start of driving (S100).
The measuring unit 92 transmits a signal instructing the imaging unit 94 to take an image of the exposed portion 25bh based on the signal transmitted from the control unit 72. The imaging unit 94 takes the image of the exposed portion 25bh based on the signal transmitted by the measuring unit 92. Next, the imaging unit 94 digitally converts the taken image and supplies the image to the measuring unit 92. The measuring unit 92 performs predetermined image processing of the supplied digital data and calculates the measured area value obtained by measuring the area of the exposed portion 25bh (S101). Then, the measuring unit 92 transmits the obtained measured area value to the control unit 72 (S102).
The control unit 72 transmits the transmitted measured area value to the comparing unit 76. The comparing unit 76 compares the transmitted measured area value with the limit area value as the predetermined value stored in advance (S103).
When the measured area value exceeds the limit area value as the predetermined value, the comparing unit 76 transmits a signal indicating “measured area value>limit area value” to the control unit 72. The control unit 72 transmits a signal indicating disapproval of driving to the informing unit 74 based on the signal indicating “measured area value>limit area value”. The control unit 72 further drives the informing unit 74 (S105).
The informing unit 74 displays disapproval of driving on the display device (not shown) based on the signal indicating disapproval of driving transmitted by the control unit 72 to thereby inform outside of the status in which the driving is not approved (S106).
The control unit 72 transmits the signal indicating disapproval of driving to the informing unit 74 as well as supplies a signal for stopping driving of the thermal printer Z to respective members to thereby stop the driving of the thermal printer Z.
When the measured area value does not exceed the limit area value as the predetermined value, the comparing unit 76 transmits a signal indicating “limit area value>measured area value” to the control unit 72. The control unit 72 transmits a signal indicating approval of driving to the informing unit 74 based on the signal indicating “limit area value>measured area value”. The control unit 72 further drives the informing unit 74 (S107).
The informing unit 74 displays approval of driving on the display device (not shown) based on the signal indicating approval of driving transmitted by the control unit 72 to thereby inform outside of the status in which the driving is approved (S108).
The control unit 72 transmits the signal indicating approval of driving to the informing unit 74 as well as supplies a signal for starting driving of the thermal printer Z to respective members to thereby start the driving of the thermal printer Z.
When using the method of driving the thermal printer Z as described above, the degree of abrasion of the first protective film 25 can be detected before starting driving of the thermal printer Z as well as blur of printing or damage of the heat-generating portions 9 which may occur due to the abraded first protective film 25 can be reduced. It is also possible to detect the degree of abrasion of the first protection film 25 easily by detecting the degree of abrasion of the first protective film 25 by the area of the exposed portions 25bh.
One embodiment of the invention has been explained as the above, however, the invention is not limited to the above embodiment and various alterations may occur within a scope not departing from the gist thereof. Though the example in which the thermal head X1 is used for the thermal printer Z has been shown, it is also possible to use either of thermal heads X2 and X3. It is further possible to use thermal heads X1 to X3 according to plural embodiments in combination.
For example, the opening 25ch penetrating the abrasion resistance layer 25c is formed only in the abrasion resistance layer 25c in the thermal head X1 according to the embodiment as shown in
Additionally, the first protective layer 25 is formed by a stacked body obtained by stacking three layers of the electrical insulating layer 25a, the conductive layer 25b and the abrasion resistance layer 25c in the thermal head X1 according to the embodiment as shown, for example, in
Though the openings 25ch of the abrasion resistance layer 25c are formed on both end portions of the raised portion 13b of the thermal storage layer 13 in the thermal head X1 according to the embodiment as shown, for example,
Additionally, in the thermal storage layer 13, the raised portion which is partially raised on the substrate 7 is formed by providing the raised portion 13b partially raised from the base portion 13a on the base portion 13a in the thermal head X1 according to the embodiment as shown, for example,
Further, the thermal storage layer 13 may be formed only by the base portion 13a without providing the raised portion 13b. The thermal storage layer 13 itself may not be formed on the substrate 7. Even when the thermal head X1 is configured as the above, the medium is allowed to contact the exposed portions 25ch by the platen roller as described above.
A thermal head X3 according to another embodiment of the invention will be explained with reference to
In the thermal head X3, the exposed portion 25bh of the conductive layer 25b extends along the arrangement direction as well as provided on the downstream side of the heat-generating portions 9 in the conveying direction. The exposed portion 25bh is provided on the raised portion 13b of the thermal storage layer 13, which is provided adjacent to the heat-generating portions 9 over a region from the heat-generating portions 9 positioned at one end in the arrangement direction toward the heat-generating portions 9 positioned at the other end.
As shown in
Additionally, the exposed portion 25bh is provided on the downstream side of the heat-generating portions 9 in the conveying direction, therefore, the medium can be peeled off from the thermal head X3 efficiently after relieving static electricity by the exposed portion 25bh.
The example in which the exposed potion 25bh and the surface of the abrasion resistance layer 25c form approximately the same plane in the thermal head X3 has been shown, however, the structure is not limited to this. For example, the exposed portion 25bh may be provided at a lower position than the surface formed by the abrasion resistance layer 25c. In other words, the exposed portion 25bh may form a concaved portion (not shown). Also in this case, as the platen roller is made of rubber as described above, the roller can contact the exposed portion 25bh by deformation of rubber, which can relieve static electricity accumulated in the medium. It is also possible to reduce the possibility that the exposed portion 25bh contacts the medium excessively by forming the concave portion by the exposed portion 25bh. The depth of the concave portion may be appropriately set in accordance with the hardness of rubber used in the platen roller.
The exposed portion 25bh may also be provided at a higher position than the surface formed by the abrasion resistance layer 25c. In other words, the exposed portion 25bh may form a convex portion (not shown). In this case, it is possible to allow the exposed portion 25gh to contact the medium without being abraded particularly when the hardness of rubber in the platen roller is low, which can reduce damage of the heat-generating portions 9.
The thermal heads X1 to X3 in which the opening 25ch is provided in the abrasion resistance layer 25c and part of the conductive layer 25 exposed from the opening 25ch is the exposed portion 25bh have been exemplified, however, the structure is not limited to the above. For example, when the conductive layer 25b is provided so that the area thereof is larger than the abrasion resistance layer 25c in a plan view, part of the conductive layer 25b can form the exposed portion 25bh exposed from the abrasion resistance layer 25c.
The method of driving the thermal head printer Z at the time of starting driving has been exemplified, the method is not limited to this. For example, abrasion amounts of the first protective layer 25 corresponding to areas of the exposed portion 25bh in respective media are calculated by experiments or simulations, thereby calculating the abrasion amount of the first protective layer 25 based on the measured area value of the exposed portion 25bh.
Specifically, a data table including areas of the exposed portion 25bh and abrasion amounts of the first protective layer 25 corresponding to the areas of the exposed portion 25bh in respective media P is stored in the comparing unit 76 of the controller 70 in advance.
At the time of driving the thermal printer, the measuring unit 92 of the thermal printer Z transmits a signal instructing the imaging unit 94 to take an image of the exposed portion 25bh based on the signal transmitted from the control unit 72. The imaging unit 94 takes the image of the exposed portion 25bh based on the signal transmitted by the measuring unit 92. Next, the imaging unit 94 digitally converts the taken image and supplies the image to the measuring unit 92. The measuring unit 92 performs predetermined image processing of the supplied digital data and calculates the measured area value obtained by measuring the area of the exposed portion 25bh. Then, the measuring unit 92 transmits the obtained measured area value to the control unit 72.
The control unit 72 transmits the transmitted measured area value to the comparing unit 76. The comparing unit 76 calculates a measured abrasion amount as the abrasion amount of the first protective layer 25 by referring to the transmitted measured area value and the data table stored in advance. Then, the comparing unit 76 compares a limit abrasion amount as a limit value in the abrasion amount of the first protective layer 25 stored in the comparing unit 76 in advance with the measured area value.
When the measured abrasion amount exceeds the limit abrasion amount, the comparing unit 76 transmits a signal indicating “measured abrasion amount>limit abrasion amount” to the control unit 72. The control unit 72 transmits a signal indicating disapproval of driving to the informing unit 74 based on the signal indicating “measured abrasion amount>limit abrasion amount”. The control unit 72 further drives the informing unit 74.
The informing unit 74 displays disapproval of driving on the display device (not shown) based on the signal indicating disapproval of driving transmitted by the control unit 72 to thereby inform outside of the status in which the driving is not approved.
The control unit 72 transmits the signal indicating disapproval of driving to the informing unit 74 as well as supplies a signal for stopping driving of the thermal printer Z to respective members to thereby stop the driving of the thermal printer Z.
When the measured abrasion amount does not exceed the limit abrasion amount, the comparing unit 76 transmits a signal indicating “limit abrasion amount>measured abrasion amount” to the control unit 72. The control unit 72 transmits a signal indicating approval of driving to the informing unit 74 based on the signal indicating “limit abrasion amount>measured abrasion amount”. The control unit 72 further drives the informing unit 74.
The informing unit 74 displays approval of driving on the display device (not shown) based on the signal indicating approval of driving transmitted by the control unit 72 to thereby inform outside of the status in which the driving is approved.
The abrasion amount of the first protective layer 25 is calculated based on the measured area value of the exposed potion 25bh as described above, thereby detecting whether the thermal printer Z can be actuated or not, as a result, necessity of replacing the thermal head X1 can be checked.
Accordingly, it is possible to detect the abrasion amount of the first protective film 25 of the thermal head X1 and to check the necessity of replacing the thermal head X1 without measuring the abrasion amount of the first protective film 25 by dismounting the thermal head X1 from the thermal printer. Accordingly, the thermal printer Z with improved maintainability can be obtained.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-040088 | Feb 2011 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2012/054578 | 2/24/2012 | WO | 00 | 8/23/2013 |
