Patent Grant
8953006
The present invention relates to a thermal head and a thermal printer including the same.
A variety of thermal heads have been developed as a printing device of, for example, a facsimile and a video printer. For example, PTL 1 describes a thermal head including a substrate, a plurality of heat generating members arranged on the substrate, a plurality of interconnection lines for supplying electric currents to the heat generating members, and a drive IC for controlling power supplied to the heat generating members. In addition, end portions of the plurality of interconnection lines have a plurality of pads, which are used for being connected to a plurality of terminals of the drive IC, formed therein.
In the thermal head described in PTL 1, since the plurality of heat generating members are densely arranged, the plurality of pads formed in the plurality of interconnection lines connected to the respective heat generating members are also densely arranged on the substrate in limited space. More specifically, the pads are disposed so that the lengths of the interconnection lines connected to the pads gradually increase and, thus, the pads are disposed so as to extend diagonally.
PTL 1: Japanese Unexamined Patent Application Publication No. 2000-286291
However, a problem arises in the thermal head described in PTL 1; since, as described above, the pads are disposed so as to extend diagonally, the length of each of the pads in the arrangement direction increases. As a result, the length of the substrate in the arrangement direction of the pads increases and, thus, the size of the thermal head increases.
According to an embodiment of the present invention, a thermal head includes a substrate, a plurality of heat generating members disposed on the substrate and arranged in a first direction, a drive IC disposed on the substrate and configured to control driving of the heat generating members, a plurality of pads disposed on the substrate, where the pads are electrically connected to a plurality of terminals of the drive IC, and a plurality of interconnection lines disposed on the substrate and configured to electrically connect each of the heat generating members to one of the pads. The pads are arranged in a first direction and constitute a plurality of first pad groups and a plurality of second pad groups constituted by the pads that constitute the first pad groups, and the second pad groups are arranged in the first direction so as to be shifted from each other in a second direction that differs from the first direction.
According to another embodiment of the present invention, a thermal printer includes the above-described thermal head, a transport mechanism configured to transport a medium to a point above the plurality of heat generating members, and a platen roller configured to urge the medium against the heat generating members.
According to the present invention, even when the pads for being connected to the connection terminals of the drive IC are densely disposed, a compact thermal head and a thermal printer including the thermal head can be provided.
A thermal head X1 according to a first embodiment of the present invention is described below with reference to the accompanying drawings. As illustrated in
The heat dissipator 1 is made of a metallic material, such as copper or aluminum, and includes a baseplate portion 1a having a rectangular shape in plan view and a protrusion portion 1b protruding along one of the long sides of the baseplate portion 1a. As illustrated in
As illustrated in
The substrate 7 has one long side 7a, the other long side 7b, one short side 7c, and the other short side 7d, and is made of an electrically insulating material, such as alumina ceramic, or a semiconductor material, such as a single crystal silicon.
As illustrated in
The thermal storage layer 13 can be formed of, for example, glass having a low heat conductivity, and temporarily accumulates part of heat generated by the heat generating members 9. Thus, it is functioned that the time required for raising the temperature of the heat generating members 9 can be reduced, and the thermal responsiveness of the thermal head X1 can be improved.
The glass that forms the thermal storage layer 13 can be formed by applying predetermined glass paste obtained by mixing an appropriate organic solvent with glass powders onto the top surface of the substrate 7 using an existing technique (e.g., screen printing) and, thereafter, firing the substrate 7 at a high temperature. Examples of the glass used 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 electrical resistance layer 15 is formed on the top surface of the thermal storage layer 13. The electrical resistance layer 15 is located between the thermal storage layer 13 and a common electrode interconnection line 17 (described in more detail below), individual electrode interconnection lines 19, a ground electrode interconnection line 21 and IC control interconnection lines 23. As illustrated in
The exposed areas of the electrical resistance layer 15 form the heat generating members 9. As illustrated in
The electrical resistance layer 15 is made of a material having a relatively high electrical resistance, such as a TaN based material, a TaSiO based material, a TaSiNO based material, a TiSiO based material, a TiSiCO based material, or a NbSiO based material. Accordingly, when a voltage is applied between the common electrode interconnection line 17 and one of the individual electrode interconnection lines 19 and, thus, an electric current is supplied to one of the heat generating members 9, the one of the heat generating members 9 generates heat due to Joule Heating.
As illustrated in
As illustrated in
As illustrated in
As illustrated in
As illustrated in
Although not illustrated, a plurality of first connection terminals 11a connected to the individual electrode interconnection lines 19 and a plurality of second connection terminals 11b connected to the ground electrode interconnection line 21 is provided so as to correspond to each of the individual electrode interconnection lines 19. The plurality of first connection terminals 11a are connected to the individual electrode interconnection lines 19 in one-to-one correspondence. In contrast, the plurality of second connection terminals 11b is all connected to the ground electrode interconnection line 21. Note that the first connection terminals 11a according to the present embodiment correspond to connection terminals of the present invention.
Connection between the first connection terminal 11a of the drive IC 11 and the individual electrode interconnection lines 19 is described in detail below. As described above, for convenience of description, the plurality of heat generating members 9 are simplified to be illustrated in
In the present embodiment, as illustrated in
The heat generating members 9 are sequentially arranged in the first direction L, and each of the first heat generating member groups 901A, 901B, and 901C is constituted by some of the sequentially arranged heat generating members 9. In the first heat generating member group 901A, second heat generating member groups 902Aa, 902Ab, and 902Ac are constituted by a plurality of heat generating members 9 that constitute the first heat generating member group 901A. In the first heat generating member group 901B, second heat generating member groups 902Ba, 902Bb, and 902Bc are constituted by a plurality of heat generating members 9 that constitute the first heat generating member group 901B. In the first heat generating member group 901C, second heat generating members 902Ca, 902Cb, and 902Cc are constituted by a plurality of heat generating members 9 that constitute the first heat generating member group 901C.
The plurality of pads 20 are arranged in the first direction L, and include first pad groups 201A, 201B, and 201C that are constituted by a plurality of pads 20. In the first pad group 201A, second pad groups 202Aa, 202Ab, and 202Ac are constituted by a plurality of pads 20 that constitute the first pad group 201A. In the first pad group 201B, second pad groups 202Ba, 202Bb, and 202Bc are constituted by a plurality of pads 20 that constitute the first pad group 201B. In the first pad group 201C, second pad groups 202Ca, 202Cb, and 202Cc are constituted by a plurality of pads 20 that constitute the first pad group 201C.
Arrangement of the pads 20 is described below with reference to the first pad group 201A. Each of the second pad groups 202Aa, 202Ab, and, 202Ac is constituted by the pads 20 arranged in a second direction W. More specifically, the second pad group 202Aa is constituted by pads 20a, 20b, and 20c. The second pad groups 202Aa, 202Ab, and, 202Ac are arranged in the first direction L. In addition, the second pad groups 202Aa, 202Ab, and, 202Ac are arranged so as to be offset from each other in the second direction W. Thus, the pads 20 that constitute a second pad group 202 are provided in a staircase pattern in which the distances from the heat generating members 9 vary in stepwise manner.
In this manner, the pads 20 that constitute each of the second pad groups 202 are arranged in the second direction W, and the second pad groups 202 are arranged in the first direction L. Accordingly, the arrangement area of the pads 20 in the second direction W can be reduced, as compared with the configuration in which the pads 20 are arranged diagonally. As a result, the length of the substrate 7 in the second direction W can be reduced and, thus, the size of the thermal head X1 can be reduced. In addition, since pads constituting the second pad groups 202 are arranged in the second direction W, the arrangement area of the pads 20 in the first direction L can be also reduced. As a result, the length of the substrate 7 in the first direction L can be reduced and, thus, the size of the thermal head X1 can be reduced even in the first direction L. This is particularly effective for the thermal head X1 of a high density interconnection line type for which the arrangement area of the pads 20 tends to increase due to a large number of the pads 20.
Since the arrangement area of the pads 20 of the thermal head X1 can be reduced in the second direction W, the distance between the heat generating members 9 and the pad 20 can be reduced, as compared with the existing technology in which the pad 20 are diagonally arranged. More specifically, the distance between the pad 20i located in a seventh step that is far from the heat generating members 9 and a heat generating members 9i can be reduced, as compared with the existing technology. In this manner, the distance between the pad 20i located in the seventh step that is far from the heat generating members 9i and the heat generating members 9 can be made close to the distance between the pad 20a located in a first step that is close to the heat generating members 9 and a heat generating members 9a.
Accordingly, the length of the individual electrode interconnection lines 19 that electrically connects the heat generating members 9i to the pad 20i can be made close to the length of the individual electrode interconnection lines 19 that electrically connects the heat generating members 9a to the pad 20a. Consequently, a difference in the electrical resistance of the individual electrode interconnection lines 19 between the heat generating members 9a and the heat generating members 9i can be made small. As a result, a difference in the heating temperature among the heat generating members 9 can be reduced.
In the thermal head X1, the second pad groups 202 are disposed so as to be offset from each other in the first direction L. That is, the second pad groups 202 are disposed so as to move away from the heat generating members 9. Accordingly, even when a large number of the pads 20 are disposed, the individual electrode interconnection lines 19 can be disposed at a high density. That is, by disposing only the pad 20a of the second pad group 202Aa in the first step, disposing only a pad 20d of the second pad group 202Ab in the second step, and disposing the pad 20b of the second pad group 202Aa and a pad 20g of the second pad group 202Ac in the third step where the need for the space for the individual electrode interconnection lines 19 for the pads 20a and 20d is eliminated, the pads 20 and the individual electrode interconnection lines 19 can be disposed at a high density. In this manner, the size of the thermal head X1 can be reduced more in the first direction L.
As illustrated in
As described above, since the first pad groups 201 have the particular pad arrangement pattern and a plurality of the first pad groups 201 are arranged in the first direction L, in a probe process in which electrical connection between the heat generating members 9 and the pad 20 is detected, a tact time of the probe process can be reduced. That is, by producing probe needles that match the particular pad arrangement pattern of the first pad groups 201 and performing the probe process for each of the first pad groups 201, the tact time required for the probe process can be reduced, as compared with the probe process performed for each of the pad 20.
The arrangement of the pads 20 is described in more detail below with reference to the first pad group 201A.
When viewed in the first direction L, in the neighboring second pad groups 202Aa and 202Ab of the thermal head X1, the pad 20d in the second pad group 202Ab is disposed between the pads 20a and 20b in the second pad group 202Aa, and the pad 20d in the second pad group 202Ab is disposed between the pads 20b and 20c that constitute the second pad group 202Aa. Accordingly, the arrangement area of the pads 20 in the first direction L can be reduced. In the thermal head X1 illustrated in
In addition, each of the distances between the pad 20a, 20d and 20g which are located so as to be the closest to the heat generating members 9 in each of the second pad groups 202Aa, 202Ab, and 202Ac, and the heat generating members 9a, 9d and 9g, respectively, increase as moving toward the first direction L. Accordingly, the lengths of the individual electrode interconnection lines 19 that connects the neighboring heat generating members 9c and 9d to the second pad group 202Aa and 202Ab can be made close. That is, the distance between the heat generating members 9c and the pad 20c that constitutes the second pad group 202Aa can be made close to the distance between the heat generating members 9d and the pad 20d that constitutes the second pad group 202Ab, and therefore, the electrical resistances of the individual electrode interconnection lines 19 for the neighboring heat generating members 9c and 9d can be made close to each other. Consequently, the heating temperatures of the neighboring heat generating members 9c and 9d can be made close to each other. Note that the neighboring heat generating members 9 indicate the heat generating members 9 that are disposed next to each other in the first direction L, and a voltage is sequentially applied when printing is performed.
Note that the first direction L represents the arrangement direction of the heat generating members 9, and the second direction W represents a direction that is different from the first direction L and is preferably a direction perpendicular to the first direction L. Also, “the second direction W is perpendicular to the first direction L” means that the angle formed by the first direction L and the second direction W is not limited to exactly 90 degrees, but that the angle has an allowance of about 5 degrees.
The IC control interconnection lines 23 are provided to control the drive IC's 11, and each IC control interconnection line 23 includes an IC power supply interconnection line 23a and an IC signal interconnection line 23b as illustrated in
As illustrated in
As illustrated in
The end power supply electrode portion 23aE and the middle power supply electrode portion 23aM are electrically connected to each other inside the drive IC 11 to which both the portions are connected. In addition, the neighboring middle power supply electrode portions 23aM are electrically connected to each other inside the drive IC 11 to which both the portions are connected.
As described above, by connecting each IC power supply interconnection line 23a to each of the drive IC's 11, the each IC power supply interconnection line 23a electrically connects between the each drive IC's 11 and the FPC 5. In this manner, as described below, an electric current is supplied from the FPC 5 to each of the drive IC's 11 via the end power supply electrode portions 23aE and the middle power supply electrode portions 23aM.
As illustrated in
As illustrated in
In the middle signal interconnection line portion 23bM, one end thereof is disposed on the arrangement area of one of the neighboring drive IC's 11, and extends around the periphery of the middle power supply electrode portion 23aM while the other end is disposed on the arrangement area of the other neighboring drive IC 11. In the middle signal interconnection line portion 23bM, one end thereof is connected to one of the neighboring drive IC's 11, and the other end is connected to the other neighboring drive IC 11.
The end signal interconnection line portion 23bE and the middle signal interconnection line portion 23bM are connected to each other inside the drive IC 11 to which both the portions are connected. In addition, the neighboring middle signal interconnection line portions 23bM are electrically connected to each other inside the drive IC to which both the portions are connected.
By connecting the IC signal interconnection lines 23b to each of the drive IC's 11 in this manner, the IC signal interconnection lines 23b electrically connect each of the drive IC 11 to the FPC 5. Thus, as described below, a control signal transmitted from the FPC 5 to the drive IC 11 via the end signal interconnection line portion 23bE is further transmitted to the neighboring drive IC 11 via the middle signal interconnection line portion 23bM.
Each of the above-described electrical resistance layer 15, common electrode interconnection line 17, individual electrode interconnection lines 19, ground electrode interconnection line 21, and IC control interconnection lines 23 can be formed by, for example, sequentially stacking, on the thermal storage layer 13, the material layers constituting each thereof using an existing thin film forming technique such as a sputtering method and, subsequently, and then by processing the stacked body into a predetermined pattern using an existing photolithography technique, an existing etching technique, or the like.
As illustrated in
The first protective layer 25 can prevent part of the heat generating members 9, part of the common electrode interconnection line 17, and part of the individual electrode interconnection lines 19 which have been coated from being oxidized by the reaction with oxygen, can prevent them from being eroded due to, for example, adhesion of water in the air, and can reduce the possibility of wearing due to contact with a print medium. The first protective layer 25 can be formed from, for example, an SiC based material, an SiN based material, an SiO based material, an SiON based material, or the like. In addition, the first protective layer 25 can be formed using, for example, an existing thin film forming technique such as a sputtering technique or a vapor-deposition technique, or an existing thick film forming technique such as a screen printing technique. Note that the first protective layer 25 may be formed by stacking a plurality of material layers.
In addition, as illustrated in
Note that an opening (not illustrated) is formed in the second protective layer 27 for allowing the ends of the individual electrode interconnection lines 19 connected to the drive IC's 11, the ends of a second middle area 21N and a third middle area 21L of the ground electrode interconnection line 21, and the end of the IC control interconnection lines 23 to be exposed therethrough, and these interconnection lines are connected to the drive IC's 11 through the opening. In addition, after the drive IC 11 is connected to the individual electrode interconnection line 19, the ground electrode interconnection line 21, and the IC control interconnection line 23, the drive IC 11 is covered and sealed by a cover members 29 made of resin, such as epoxy resin and silicon resin, in order to protect the drive IC 11 itself and a connection portion between the drive IC 11 and each of the interconnection lines.
As illustrated in
More specifically, the printed interconnection lines formed inside are respectively connected to the end of the sub interconnection line portions 17b of the common electrode interconnection line 17, the end of the ground electrode interconnection line 21, and the end of the IC control interconnection lines 23 using solder paste 33 (refer to
Once the connector 31 is electrically connected to, for example, the external power supply device or the external control device which are not illustrated, the common electrode interconnection line 17 is connected to a plus terminal of the power supply device that is maintained at a positive potential of, for example, 20 to 24 V. The individual electrode interconnection lines 19 is connected to a minus terminal of the power supply device that is maintained at a ground potential of, for example, 0 to 1 V. Accordingly, when the switching element of the drive IC 11 is in an ON mode, an electric current is supplied to the heat generating members 9 and, thus, the heat generating members 9 generates heat.
In addition, like the common electrode interconnection line 17, when the connector 31 is electrically connected to, for example, the external power supply device or the external control device which are not illustrated, the IC power supply interconnection line 23a of the IC control interconnection lines 23 is connected to the plus terminal of the power supply device that is maintained at a positive potential. In this manner, an electric current for operating the drive IC 11 is supplied to the drive IC 11 due to a potential difference between the IC power supply interconnection line 23a to which the drive IC 11 is electrically connected and the ground electrode interconnection line 21.
Furthermore, the IC signal interconnection line 23b of the IC control interconnection lines 23 is connected to a control device that controls the drive IC 11. Thus, a control signal is transmitted from the control device to the drive IC 11 via the end signal interconnection line portion 23bE, and the control signal transmitted to the drive IC 11 is further transmitted to the neighboring drive IC via the middle signal interconnection line portion 23bM. By using the control signal for controlling ON mode/OFF mode of the switching element in the drive IC 11, one of the heat generating members 9 can be selectively generate heat.
A thermal printer according to an embodiment of the present invention is described next with reference to
As illustrated in
The transport mechanism 40 is provided for transporting the medium P such as a thermal paper and an image receiving paper onto which ink is transferred in the direction indicated by an arrow S in
The platen roller 50 is provided for pushing the medium P against the heat generating members 9 of the thermal head X1, is disposed so as to extend in a direction perpendicular to the transport direction S of the medium P, and is supported at the ends thereof in a rotatable manner with the medium P pushing against the heat generating members 9. For example, the platen roller 50 can be formed by covering a cylindrical shaft body 50a made of a metal, such as a stainless steel, with an elastic member 50b made of, for example, butadiene rubber.
The power supply device 60 is provided for supplying an electric current for causing the heat generating members 9 of the thermal head X1 to generate heat in the above-described manner and an electric current for operating the drive IC's 11. The control device 70 is provided for supplying, to the drive IC's 11, control signals for controlling the operations performed by the drive IC's 11 so that the heat generating members 9 of the thermal head X1 are selectively generate heat in the above-described manner.
As illustrated in
A thermal head X2 according to a second embodiment is described with reference to
Connection of the second pad groups 202Aa, 202Ab and 202Ac to the second heat generating member groups 902Aa, 902Ab, and 902Ac is described next.
The second pad group 202Aa is connected to the second heat generating members 902Aa, and the heat generating member 9a is connected to the pad 20a located in the fifth step. In addition, a heat generating member 9b that is adjacent to the heat generating member 9a is connected to the pad 20b located in the third step. Furthermore, the heat generating member 9c that is adjacent to the heat generating member 9b is connected to the pad 20c located in the first step. That is, the pads 20a, 20b, and, 20c that constitute the second pad group 202Aa are connected to the heat generating members 9a, 9b, and 9c in the order of the distance between the pads 20a, 20b and 20c, and the heat generating members 9a, 9b and 9c from longest to shortest. This also applies to the second pad groups 202Ab and 202Ac.
In addition, since the first pad groups 201A, 201B, and, 201C are arranged in the first direction L, small is the distance between the pad 20i connected to the heat generating member 9i that is arranged as the last heat generating member among the heat generating members 20a to 20i in the first heat generating member 901A and the pad 20a connected to the heat generating member 9a that is arranged as the last of the first heat generating member 901B.
Accordingly, compared to an existing configuration in which the pads 20 are diagonally disposed, the length of the individual electrode interconnection line 19 that connects the heat generating member 9i which is arranged last in the first heat generating member group 901A to the pad 20i can be made close to the length of the individual electrode interconnection line 19 that connects the heat generating member 9a which is arranged first in the first heat generating member group 901B to the pad 20a. As a result, the electrical resistances of the individual electrode interconnection lines 19 connected to the heat generating members 9i and 9a, which are disposed next to each other, can be made close to each other and, thus, the heating temperatures of the heat generating members 9i and 9a can be made close to each other.
The thermal head X1 has a difference in an electrical resistance of the individual electrode interconnection line 19 for 6 steps between the first pad group 201A and the first pad 201B corresponds to six steps, and in contrast, the thermal head X2 has, by using such arrangement of the pads 20, the difference in the electrical resistance of the individual electrode interconnection line 19 for two steps.
A thermal head X3 according to a third embodiment is described with reference to
The wide width portion 24 is provided on some of the individual electrode interconnection lines 19 in the thermal head X3. More specifically, the wide width portion 24 is provided on the individual electrode interconnection lines 19 for the fifth step and the subsequent steps have. In this manner, an increase in an electrical resistance caused by an increase in the length of the individual electrode interconnection lines 19 can be reduced.
The wide width portion 24 is a portion wider than the other portions of the individual electrode interconnection lines 19, and has a capability of reducing the electrical resistance because of the wide width. The width of the wide width portion 24 may be changed in accordance with the position of the individual electrode interconnection lines 19, and is provided such that, for example, the width of the wide width portion 24 provided in the fifth step may be larger than the width portion 24 provided in the fourth step. Since the margin of the placement area of the pad 20 increases as the pad 20 is located farther away from the heat generating members 9 in the second direction W, it is preferable that the wide width portions 24 increase toward the second direction.
In addition, in the thermal head X3, the auxiliary electrode 22 are provided on the pads 20a, 20d, and 20g that constitute the first pad groups 201A, 201B, and, 201C.
When a probe process is performed after probe needles are positioned at pads on the side of the heat generating members, it is possible to create defective products by detection failures when the probe needles do not contact with pads located far from the heat generating members.
In contrast, in the thermal head X3, the auxiliary electrode 22 is provided on the pads 20a, 20d, and 20g that constitute the first pad groups 201A, 201B, and, 201C and therefore, even when the positions of the probe needles to be contact with the pads 20a, 20d, and 20g are shifted a little, the probe test can be accurately performed, and the probability of a good pad being detected as a defective pad can be reduced.
The auxiliary electrode 22 can be formed of a material that is the same as the individual electrode interconnection lines 19, and can be formed at the same time as the individual electrode interconnection lines 19 is formed. Note that the auxiliary electrode 22 may be formed integrally with the individual electrode interconnection line 19. That is, the sizes of the pads 20a, 20d, and 20g that constitute the first pad groups 201A, 201B, and, 201C may be made larger than the sizes of the other pads 20.
Note that as described above, even though in some cases, Ni or AI, for example, is plated on the pads 20, plating is not necessarily performed on the auxiliary electrode 22. Even when plating is not performed on the auxiliary electrode 22, the probability of detecting a defective pad during the probe process can be reduced.
In addition, while the above description has been made with reference to the thermal head X3 having the auxiliary electrodes 22 for only the pads 20a, 20d, and 20g located in the seventh step, the configuration is not limited thereto. For example, the auxiliary electrode 22 may be provided for the pads 20a, 20b, 20h, and 20g in the fifth step and the subsequent steps. Furthermore, among the pads 20 that constitute the second pad group 202, the auxiliary electrode 22 may be provided in the pads 20a, 20d, and 20g that are the farthest from the heat generating members 9. In the above-described two cases, the probability of detecting a defective pad during the probe process can be reduced.
A thermal head X4 according to a fourth embodiment is described with reference to
Connections between the heat generating members 9 and the pads 20 of the thermal head X4 are described below with reference to the first pad group 201A. A first distance between a heat generating member 9a and a pad 20a is larger than a second distance between a heat generating member 9b and a pad 20b. The second distance is larger than a third distance between a heat generating member 9c and a pad 20c. Accordingly, the distances between the heat generating members 9a, 9b and 9c and the pads 20a, 20b and 20c is getting shorter as moving toward the first direction L in the first pad group 202Aa.
A fourth distance between a heat generating member 9d and a pad 20d is shorter than a fifth distance between a heat generating member 9e and a pad 20e. The fifth distance is shouter than a sixth distance between a heat generating member 9f and a pad 20f. Accordingly, it is configured that the distances between the heat generating members 9d, 9e and 9f and the pads 20d, 20e and 20f is getting longer as moving towards the first direction L in the first pad group 202Ab.
In addition, a seventh distance between a heat generating member 9g and a pad 20g is larger than a eighth distance between a heat generating member 9h and a pad 20h. The eighth distance is larger than a ninth distance between a heat generating member 9i and a pad 20i. The pads 20g, 20h, and 20i that constitute the second pad group 202Ac are connected to the heat generating members 9g, 9h, and 9i, respectively, in the order from the largest distance between the heat generating members 9 and the pads 20 to the smallest. Accordingly, it is configured that the distances between the heat generating members 9g, 9h and 9i and the pads 20g, 20h and 20i are getting shorter as moving towards the first direction L. That is, in the thermal head X4, the heat generating members 9 and the pads 20 are electrically connected so as to meander toward the first direction L.
Since the thermal head X4 has such a configuration, when the second pad group 202Aa is connected to the heat generating members 9, the distances between the heat generating members 9 and the pad 20 gradually decrease toward the first direction L from the length in the fifth step to the length to the second step. When the second pad group 202Ab is connected to the heat generating members 9, the distances between the heat generating members 9 and the pads 20 gradually increase from the length in the third step to the length in the sixth step. When the second pad group 202Ac is connected to the heat generating members 9, it is configured that the distances between the heat generating members 9 and the pads 20 gradually decrease from the length in the seventh step to the length in the third step.
In this manner, the distances between the heat generating members 9 and the pads 20 continuously change as moving toward the first direction L, thereby making the electrical resistances of the individual electrode interconnection lines 19 for the neighboring heat generating members 9 close to each other. Accordingly, the heating temperatures of the neighboring heat generating members 9 can be made close to each other.
In addition, since the first pad groups 201A, 201B, and, 201C are arranged in the first direction L, the electrical resistances of the individual electrode interconnection lines 19 for the neighboring heat generating members 9 between the first pad groups 201A, 201B, and, 201C can be made close to each other. Accordingly, the heating temperatures of the neighboring heat generating members 9 can be made close to each other.
More specifically, the pad 20i connected to the heat generating member 9i located last in the first pad group 201A is positioned in the third step, and the pad 20a connected to the heat generating member 9a located first in the first pad group 201B is positioned in the fifth step. Accordingly, even at the boundary between the first pad groups 201, the electrical resistances for the neighboring heat generating members 9 can be made close to each other.
Note that description has been made with reference to the position of the pad 20i connected to the heat generating member 9i located last in the first pad group 201A being in the third step and the position of the pad 20a connected to the heat generating member 9a located first in the first pad group 201B being in the fifth step, the configuration is not limited thereto. For example, by shifting the first pad group 201B in a direction opposite to the second direction W by two steps, the position of the pad 20i connected to the heat generating member 9i located last in the first pad group 201A may be next to the position of the pad 20a connected to the heat generating member 9a located first in the first pad group 201B. In this manner, a difference in electrical resistances between the electrical resistances of the individual electrode interconnection lines 19 in the first pad groups 201 can be reduced more. That is, a difference in electrical resistances of an individual electrode interconnection line 19 connecting 9i with 20i and an individual electrode interconnection line 19 connecting 9a with 20a can be reduced. Note that when the pads 20 are disposed next to each other, it is preferable that the pads 20 be disposed in the same step. That is, it is preferable that the distances between the heat generating members 9 and the pads 9 be the same. In this manner, a difference between the electrical resistances of the neighboring pads 20 can be reduced.
While the present invention has been described with reference to the embodiments, the scope of the invention should not be construed as being limited by the embodiment. Various modifications can be made without departing from the scope of the present invention.
For example, while the above-described embodiment has been described with reference to the thermal head X1 having the rectangular pads 20, as illustrated in
In addition, in the thermal head X1 according to the above-described embodiment, although each of the first heat generating member groups 901 is constituted by nine heat generating members 9, each of the second heat generating member groups 902 is constituted by three heat generating members 9, and these are respectively connected to the first heat generating member groups 901 and the second heat generating member groups 902 as illustrated in
Still furthermore, while the first direction L is perpendicular to the second direction W in the thermal head X1, the configuration is not limited thereto. Since it is enough that the second pad groups are arranged in a direction farther away in the first direction L, it is only required that the second direction W differs from the first direction L.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-068184 | Mar 2011 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2012/057499 | 3/23/2012 | WO | 00 | 9/25/2013 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2012/133178 | 10/4/2012 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5162191 | Sedberry | Nov 1992 | A |
| 5317342 | Sedberry | May 1994 | A |
| 5416502 | Sedberry | May 1995 | A |
| 5488394 | Sedberry | Jan 1996 | A |
| 5624708 | Sedberry | Apr 1997 | A |
| Number | Date | Country |
|---|---|---|
| 2-151452 | Jun 1990 | JP |
| 5-031955 | Feb 1993 | JP |
| 2000286291 | Oct 2000 | JP |
| Entry |
|---|
| International Search Report, PCT/JP2012/057499, Apr. 9, 2012, 2 pp. |
| Number | Date | Country | |
|---|---|---|---|
| 20140022325 A1 | Jan 2014 | US |
