JP2005169855A - Thermal head and manufacturing method therefor - Google Patents
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- JP2005169855A JP2005169855A JP2003413542A JP2003413542A JP2005169855A JP 2005169855 A JP2005169855 A JP 2005169855A JP 2003413542 A JP2003413542 A JP 2003413542A JP 2003413542 A JP2003413542 A JP 2003413542A JP 2005169855 A JP2005169855 A JP 2005169855A
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Abstract
Description
本発明は、例えばフォトプリンタに搭載されるサーマルヘッド及びその製造方法に関する。 The present invention relates to a thermal head mounted on, for example, a photo printer and a manufacturing method thereof.
図８は、従来構造のサーマルヘッドの一例を示す断面図である。サーマルヘッドは一般に、蓄熱層１１１を備えた基板上に、複数の発熱抵抗体１１２と、この発熱抵抗体１１２に通電するための電極１１３と、これら発熱抵抗体１１２及び電極１１３の一部を保護する耐磨耗保護層１１４とを有しており、印刷媒体をプラテンローラに巻きつけた状態で、インクリボンを介して該印刷媒体に圧接することで印字している。図８に示すサーマルヘッドは、蓄熱層１１１が凸形状をなしており、印刷時に印刷媒体に対してより大きな圧力を加えることで印字品質を向上させている。この凸型タイプでは、通常、発熱抵抗体１１２は凸形状の頂上位置Ｐに配置され、この凸形状の曲率半径は一様になっている。 FIG. 8 is a cross-sectional view showing an example of a thermal head having a conventional structure. In general, a thermal head protects a plurality of heating resistors 112, an electrode 113 for energizing the heating resistors 112, and the heating resistors 112 and a part of the electrodes 113 on a substrate having a heat storage layer 111. The wear-resistant protective layer 114 is printed, and printing is performed by press-contacting the print medium via an ink ribbon in a state where the print medium is wound around a platen roller. In the thermal head shown in FIG. 8, the heat storage layer 111 has a convex shape, and the printing quality is improved by applying a larger pressure to the printing medium during printing. In this convex type, normally, the heating resistor 112 is disposed at the top position P of the convex shape, and the curvature radius of the convex shape is uniform.
近年では、低コスト化を図るべく、１枚の基板で形成可能なヘッド個数を増大してサーマルヘッド全体を小型化することが進められている。凸形タイプのサーマルヘッドの小型化を実現する際、上述の形状及び構造を保持したまま単純にサイズを小さくしただけでは、基板を印刷媒体に対して傾斜させないと電極１１３とインクリボン（インクフィルム）とが触れてしまい、また、基板をインクリボンに対して傾斜させると発熱抵抗体１１２とインクリボンとの接触効率が低下するという不具合があった。この不具合を解消するには、基板表面からの距離が最大となる蓄熱層１１１の頂上位置からずらした位置に、発熱抵抗体１１２を設けることが提案されている。ここで、蓄熱層１１１の頂上位置Ｐからの発熱抵抗体１１２の偏向角度を一定としたとき、蓄熱層１１１の曲率半径が大きいほど、発熱抵抗体１１２を頂点位置Ｐに設けた場合と偏向位置に設けた場合で発熱抵抗体１１２の表面高さのずれが増大し、発熱抵抗体１１２とインクリボンの接触が悪くなることがわかる。また、蓄熱層１１１の曲率半径が大きいと、発熱抵抗体１１２のパターン形状を規定する露光時にフォーカスが合いづらくパターン形状の転写ずれが生じる虞があり、この転写ずれが発熱抵抗体１１２の抵抗値のばらつきにつながる。以上により、凸型タイプのサーマルヘッドの小型化には、蓄熱層１１１の曲率半径を小さくし、さらに、蓄熱層１１１の頂点位置Ｐからずらして発熱抵抗体１１２を配置することが要求される。 In recent years, in order to reduce the cost, it has been promoted to increase the number of heads that can be formed on a single substrate to reduce the size of the entire thermal head. When realizing miniaturization of the convex type thermal head, the electrode 113 and the ink ribbon (ink film) must be tilted with respect to the print medium simply by reducing the size while maintaining the shape and structure described above. In addition, when the substrate is tilted with respect to the ink ribbon, the contact efficiency between the heating resistor 112 and the ink ribbon decreases. In order to solve this problem, it has been proposed to provide the heating resistor 112 at a position shifted from the top position of the heat storage layer 111 where the distance from the substrate surface is maximum. Here, when the deflection angle of the heating resistor 112 from the top position P of the heat storage layer 111 is constant, the larger the radius of curvature of the heat storage layer 111 is, the more the heating resistor 112 is provided at the apex position P and the deflection position. It can be seen that the deviation of the surface height of the heating resistor 112 increases and the contact between the heating resistor 112 and the ink ribbon deteriorates. In addition, if the radius of curvature of the heat storage layer 111 is large, there is a possibility that a transfer deviation of the pattern shape becomes difficult to focus at the time of exposure that defines the pattern shape of the heating resistor 112, and this transfer deviation causes the resistance value of the heating resistor 112. Leads to variations. As described above, in order to reduce the size of the convex type thermal head, it is required to reduce the radius of curvature of the heat storage layer 111 and dispose the heating resistor 112 so as to be shifted from the apex position P of the heat storage layer 111.
しかしながら、従来の蓄熱層１１１の凸形状の曲率半径は一様であり、小型化のために曲率半径を小さくすると、これに伴い、発熱抵抗体１１２による印刷前にサーマルヘッドがインクリボンに圧接する範囲（当たり幅）も狭くなることから、インクリボンに発生したしわを解消できず、該インクリボンのしわがそのまま印刷画像に転写されてしまうという不具合が判明した。インクリボンは、数μｍ〜数十μｍ程度の非常に薄いテープであるため剛性が小さく、例えば送りローラのようにインクリボンを走行可能に支持する部材との接触（ストレス）により、しわが生じる。従来のサーマルヘッドは大型であったため、上記当たり幅が十分に確保され、インクリボンとサーマルヘッドの圧接により該インクリボンのしわが伸ばされた状態で発熱抵抗体による印刷が行なわれており、上述のような不具合は生じない。 However, the curvature radius of the convex shape of the conventional heat storage layer 111 is uniform, and when the curvature radius is reduced for miniaturization, the thermal head presses the ink ribbon before printing by the heating resistor 112 accordingly. Since the range (hit width) is also narrowed, it has been found that the wrinkles generated in the ink ribbon cannot be eliminated, and the wrinkles of the ink ribbon are directly transferred to the printed image. Since the ink ribbon is a very thin tape of about several μm to several tens of μm, its rigidity is low, and for example, wrinkles occur due to contact (stress) with a member that supports the ink ribbon so that it can run, such as a feed roller. Since the conventional thermal head is large, the above-mentioned contact width is sufficiently secured, and the printing with the heating resistor is performed in a state where the wrinkles of the ink ribbon are stretched by the pressure contact between the ink ribbon and the thermal head. Such a problem does not occur.
本発明は、上記課題に鑑みてなされたものであり、低コスト化及び小型化され、且つ、高品質印刷を行なうことができるサーマルヘッド及びその製造方法を得ることを目的とする。 The present invention has been made in view of the above problems, and an object of the present invention is to obtain a thermal head that can be reduced in cost and size, and that can perform high-quality printing, and a method for manufacturing the thermal head.
本発明は、インクリボンのしわが印刷画像に転写されてしまう原因が、小型化のために、発熱抵抗体による印刷の前にインクリボンとサーマルヘッドが圧接する距離が短くなった点にあることを理解してなされたもので、頂点位置と該頂点位置からずらした発熱抵抗体の配設位置との高さをほぼ同等にしつつ、サーマルヘッドがインクリボンに圧接する距離を十分に確保できれば、上述した種々の不具合が解消され、小型化と高品質印刷を同時に実現できることに着目している。 In the present invention, the reason that the wrinkles of the ink ribbon are transferred to the printed image is that the distance between the ink ribbon and the thermal head is shortened before printing by the heating resistor because of the miniaturization. As long as the distance between the thermal head and the ink ribbon can be sufficiently secured while the height of the apex position and the position of the heating resistor shifted from the apex position are substantially equal, Attention is focused on the fact that the various problems described above are eliminated, and that miniaturization and high-quality printing can be realized simultaneously.
すなわち、本発明は、平坦なヘッド基板上に、基板表面からの距離が最大となる頂点位置を有する凸形状を備えた蓄熱層と、この蓄熱層上に頂点位置からずらして配置した複数の発熱抵抗体と、複数の発熱抵抗体に通電する電極とを備え、複数の発熱抵抗体を印字媒体に対して略平行に接触させて印刷動作するサーマルヘッドにおいて、蓄熱層は、頂点位置を境に、複数の発熱抵抗体が形成されている側の素子対応部と複数の発熱抵抗体が形成されていない側の媒体圧接部とを有し、この媒体圧接部の曲率半径が素子対応部の曲率半径よりも大きいことを特徴としている。 That is, the present invention provides a heat storage layer having a convex shape having a vertex position at which the distance from the substrate surface is maximum on a flat head substrate, and a plurality of heat generations arranged on the heat storage layer while being shifted from the vertex position. In a thermal head that includes a resistor and an electrode that energizes the plurality of heating resistors, and that performs a printing operation by bringing the plurality of heating resistors into contact with the print medium substantially in parallel, the heat storage layer has a vertex position as a boundary. The element corresponding portion on the side where the plurality of heating resistors are formed and the medium pressure contact portion on the side where the plurality of heating resistors are not formed, and the radius of curvature of the medium pressure contact portion is the curvature of the element corresponding portion. It is characterized by being larger than the radius.
本発明は、製造方法の態様によれば、平坦なヘッド基板上に、該基板表面からの距離が最大となる頂点位置を有し、この頂点位置を境に、第１の曲率半径を有する素子対応部と、第１の曲率半径よりも大きい第２の曲率半径を有する媒体圧接部とを備えた凸形状の蓄熱層を形成する工程と、蓄熱層の上に抵抗層と電極を全面的に形成する工程と、電極に、蓄熱層の素子対応部の上であって前記頂点位置からずらした位置に開放部を形成し、この開放部から抵抗層を露出させて複数の発熱抵抗体を形成する工程とを有することを特徴としている。 According to the aspect of the manufacturing method of the present invention, on a flat head substrate, an element having a vertex position where the distance from the substrate surface is maximum, and having the first curvature radius with the vertex position as a boundary. Forming a convex heat storage layer having a corresponding portion and a medium pressure contact portion having a second radius of curvature larger than the first radius of curvature; and a resistance layer and an electrode over the heat storage layer Forming a plurality of heat generating resistors by forming an open portion on the electrode at a position shifted from the apex position on the element corresponding portion of the heat storage layer, and exposing the resistance layer from the open portion; And a step of performing.
上記媒体圧接部は、印刷媒体の走行方向における長さ寸法を少なくとも０．２ｍｍ以上とする。この範囲を満たすことで、サーマルヘッドとインクリボンの圧接する範囲が十分に確保され、発熱抵抗体による印刷前に、インクリボンに発生したしわを解消することができる。 The medium pressure contact portion has a length dimension in the running direction of the print medium of at least 0.2 mm. By satisfying this range, a sufficient range for the thermal head and the ink ribbon to be in pressure contact is ensured, and wrinkles generated on the ink ribbon can be eliminated before printing by the heating resistor.
媒体圧接部の表面は基板表面に平行な略平坦面で形成し、該媒体圧接部の曲率半径を∞とすることができる。 The surface of the medium pressure contact portion can be formed as a substantially flat surface parallel to the substrate surface, and the radius of curvature of the medium pressure contact portion can be ∞.
蓄熱層には、さらに、媒体圧接部につらなり該媒体圧接部よりも表面位置が低い均一膜厚の平坦部が形成されていることが好ましい。媒体圧接部よりも表面位置の低い平坦部を有することで、ヘッド小型化により媒体圧接部と駆動ＩＣの間隔距離が短くなっても、印刷時に駆動ＩＣとインクリボンの接触を回避することができる。 In the heat storage layer, it is preferable that a flat portion having a uniform film thickness is formed which is formed in the medium pressure contact portion and has a surface position lower than that of the medium pressure contact portion. By having a flat portion whose surface position is lower than that of the medium pressure contact portion, it is possible to avoid contact between the drive IC and the ink ribbon during printing even if the distance between the medium pressure contact portion and the drive IC is shortened due to downsizing of the head. .
上記製造方法では、ヘッド基板の表面領域を仮想的に複数並列したヘッド形成領域に分割し、各ヘッド形成領域に蓄熱層、発熱抵抗体及び電極を形成した後、各ヘッド形成領域毎にヘッド基板を切断することが実際的である。 In the above manufacturing method, the surface area of the head substrate is virtually divided into a plurality of head formation areas, and a heat storage layer, a heating resistor and an electrode are formed in each head formation area, and then the head substrate is formed for each head formation area. It is practical to cut
本発明によれば、頂点位置を境に素子対応部と媒体圧接部を有する凸形状の蓄熱層を形成し、媒体圧接部の曲率半径を素子対応部の曲率半径よりも大きくしたので、素子対応部では、頂点位置からずらした位置に発熱抵抗体を配置しても、頂点位置に配置した場合とほぼ同等に該発熱抵抗体の高さ位置を確保することができる。すなわち、印刷媒体と発熱抵抗体を良好に接触させることができ、また、発熱抵抗体の抵抗値のばらつきを抑えることができる。これにより、サーマルヘッドの小型化を実現することができ、小型化による生産個数の増加により、低コスト化を図れる。また、媒体圧接部では、蓄熱層の凸形状の曲率半径を一様とした場合よりもインクリボンに対して圧接する距離を長く確保され、インクリボンが素子対応部の発熱抵抗体に到達する前に、インクリボンのしわを伸長させて軽減することができる。これにより、サーマルヘッドを小型化してもインクリボンのしわが印刷画像に転写されることがなく、高品質印刷がえられる。
According to the present invention, the convex heat storage layer having the element corresponding part and the medium pressure contact part is formed at the apex position, and the curvature radius of the medium pressure contact part is larger than the curvature radius of the element corresponding part. In this case, even if the heating resistor is arranged at a position shifted from the vertex position, the height position of the heating resistor can be ensured substantially equivalent to the case where the heating resistor is arranged at the vertex position. That is, the print medium and the heating resistor can be brought into good contact, and variations in the resistance value of the heating resistor can be suppressed. As a result, the thermal head can be reduced in size, and the cost can be reduced by increasing the number of products produced by downsizing. In addition, the medium pressure contact portion ensures a longer distance to press against the ink ribbon than when the convex curvature radius of the heat storage layer is uniform, before the ink ribbon reaches the heating resistor of the element corresponding portion. In addition, the wrinkles of the ink ribbon can be reduced and reduced. Thereby, even if the thermal head is reduced in size, wrinkles of the ink ribbon are not transferred to the printed image, and high quality printing can be obtained.
図１は、本発明の第１実施形態によるサーマルヘッドを示す断面図である。本サーマルヘッド１は、別個に形成された、放熱性の高いヘッド基板１０とプリント回路基板（ＰＣＢ；Ｐｒｉｎｔ Ｃｉｒｃｕｉｔ Ｂｏａｒｄ）２０を備えている。ヘッド基板１０の上には、例えばガラスのような高断熱性材料からなる蓄熱層１１、複数の発熱抵抗体１２、電極１３及び耐磨耗保護層１４が形成されており、プリント回路基板２０には、複数の発熱抵抗部１２への通電制御を行なう駆動ＩＣ２１を含む各種回路及び素子が搭載されている。駆動ＩＣ２１は、封止樹脂２２により封止されている。封止樹脂２２は、ヘッド基板１０の耐磨耗保護層１４の表面から駆動ＩＣ２２を含むプリント回路基板２０の表面を覆って備えられ、これによりヘッド基板１０とプリント回路基板２０を接着する。 FIG. 1 is a sectional view showing a thermal head according to a first embodiment of the present invention. The thermal head 1 includes a head substrate 10 and a printed circuit board (PCB) 20 that are separately formed and have high heat dissipation. On the head substrate 10, for example, a heat storage layer 11 made of a highly heat-insulating material such as glass, a plurality of heating resistors 12, an electrode 13, and a wear-resistant protective layer 14 are formed. Are mounted with various circuits and elements including a drive IC 21 that controls energization of the plurality of heating resistor sections 12. The drive IC 21 is sealed with a sealing resin 22. The sealing resin 22 is provided so as to cover the surface of the printed circuit board 20 including the driving IC 22 from the surface of the wear-resistant protective layer 14 of the head substrate 10, thereby bonding the head substrate 10 and the printed circuit board 20.
蓄熱層１１は、ヘッド基板１０の一端部側１０ａに形成された凸形状部と、この凸形状部からヘッド基板１０の他端部側（ＰＣＢ接続端側）１０ｂへ延出された均一膜厚の平坦部１１ａとを有している。平坦部１１ａは凸形状部（媒体圧接部１１ｃ）よりも表面位置が低くなっており、平坦部１１ａの表面位置と凸形状部の最高表面位置との間には段差αが生じている。 The heat storage layer 11 has a convex portion formed on one end side 10a of the head substrate 10 and a uniform film thickness extending from the convex portion to the other end side (PCB connection end side) 10b of the head substrate 10. And a flat portion 11a. The flat portion 11a has a lower surface position than the convex portion (medium pressure contact portion 11c), and a step α is generated between the surface position of the flat portion 11a and the highest surface position of the convex portion.
凸形状部は、ヘッド基板表面からの距離（厚さ寸法）が最大となる頂点位置Ｐを有し、この頂点位置Ｐを境に形成された素子対応部１１ｂと媒体圧接部１１ｃからなる。素子対応部１１ｂは、頂点位置Ｐよりも他端部１０ｂ側に位置し、第１の曲率半径φ１で形成されている。この素子対応部１１ｂの上には、頂点位置Ｐから所定角度θだけずらした位置に、図１の紙面に対して垂直な方向に微小な間隔をあけて整列した複数の発熱抵抗体１２が配置されている。第１の曲率半径φ１は少なくとも３ｍｍ未満であり、頂点位置Ｐにおける蓄熱層１１の厚さ寸法と、頂点位置Ｐから所定角度θ偏向させた位置における蓄熱層１１の厚さ寸法との差はほぼ同等である。媒体圧接部１１ｃは、頂点位置Ｐと平坦部１１ａの間に位置し、送りローラ４１（図２）により素子対応部１１ｂへ送られるインクリボンに所定の荷重で圧接する。この媒体圧接部１１ｃは、第１の曲率半径φ１よりも大きな第２の曲率半径φ２で形成され、インクリボンの走行方向における長さ寸法Ｌ（頂点位置Ｐから平坦部１１ａまでの距離）が少なくとも０．２ｍｍ以上確保されている。具体的に第２の曲率半径φ２は３ｍｍ以上であることが好ましい。ここで、媒体圧接部１１ｃの長さ寸法Ｌを０．２ｍｍ以上としたのは、インクリボンを伸長させるために、媒体圧接部１１ｃによるインクリボンの圧接範囲をある一定以上に確保することが必要であり、実験的に下限値を求めた結果、長さ寸法Ｌが少なくとも０．２ｍｍ以上必要であることが判明したからである。 The convex portion has a vertex position P at which the distance (thickness dimension) from the head substrate surface is maximum, and is composed of an element corresponding portion 11b and a medium pressure contact portion 11c formed at the vertex position P as a boundary. The element corresponding portion 11b is positioned on the other end portion 10b side with respect to the vertex position P, and is formed with a first curvature radius φ1. On the element corresponding portion 11b, a plurality of heating resistors 12 aligned at a minute interval in a direction perpendicular to the paper surface of FIG. Has been. The first radius of curvature φ1 is at least less than 3 mm, and the difference between the thickness dimension of the heat storage layer 11 at the apex position P and the thickness dimension of the heat storage layer 11 at a position deflected from the apex position P by a predetermined angle θ is approximately. It is equivalent. The medium pressure contact portion 11c is located between the apex position P and the flat portion 11a, and is pressed against the ink ribbon sent to the element corresponding portion 11b by the feed roller 41 (FIG. 2) with a predetermined load. The medium pressure contact portion 11c is formed with a second curvature radius φ2 larger than the first curvature radius φ1, and the length L in the running direction of the ink ribbon (distance from the apex position P to the flat portion 11a) is at least. 0.2 mm or more is secured. Specifically, the second curvature radius φ2 is preferably 3 mm or more. Here, the length L of the medium pressure contact portion 11c is set to 0.2 mm or more. In order to extend the ink ribbon, it is necessary to secure the pressure contact range of the ink ribbon by the medium pressure contact portion 11c to a certain level or more. This is because, as a result of experimentally determining the lower limit, it has been found that the length L is required to be at least 0.2 mm.
複数の発熱抵抗体１２は、蓄熱層１１の上に全面的に形成された抵抗層１２’の一部であり、上述のように頂点位置Ｐから素子対応部１１ａ側に所定角度θ偏向させた位置に配置され、通電により発熱する。電極１３は、複数の発熱抵抗体１２の表面を露出させる開放部１３ｃを有し、この開放部１３ｃを介して、複数の発熱抵抗体１２ａのすべてに接続する共通電極１３ａと、各発熱抵抗体１２ａ毎に個別に接続する複数の個別電極１３ｂとにわかれている。各個別電極１３ｂには、プリント回路基板２０に設けた駆動ＩＣ２１がワイヤーボンディングにより電気的に接続されている。耐磨耗保護層１４は、共通電極１３ａ、複数の発熱抵抗体１２、及び複数の個別電極１３ｂの表面を覆って形成され、インクリボン等との接触から該共通電極１３ａ、発熱抵抗体１２及び個別電極１３ｂを保護する。 The plurality of heating resistors 12 are a part of the resistance layer 12 ′ formed on the entire surface of the heat storage layer 11, and are deflected by a predetermined angle θ from the apex position P toward the element corresponding portion 11a as described above. It is arranged at a position and generates heat when energized. The electrode 13 has an open portion 13c that exposes the surfaces of the plurality of heat generating resistors 12, and the common electrode 13a connected to all of the plurality of heat generating resistors 12a via the open portion 13c, and each heat generating resistor It is divided into a plurality of individual electrodes 13b that are individually connected every 12a. A driving IC 21 provided on the printed circuit board 20 is electrically connected to each individual electrode 13b by wire bonding. The wear-resistant protective layer 14 is formed so as to cover the surfaces of the common electrode 13a, the plurality of heating resistors 12, and the plurality of individual electrodes 13b, and from the contact with an ink ribbon or the like, the common electrode 13a, the heating resistors 12, and The individual electrode 13b is protected.
上記構成のサーマルヘッド１は、フォトプリンタやサーマルプリンタに搭載され、発熱抵抗体１２の発する熱を感熱紙３１（印刷媒体）またはインクリボン３２に与えることで印刷を行なう。図２は、サーマルヘッド１による印刷動作を説明する模式図である。感熱紙３１とインクリボン３２は、それぞれ送りローラ４１によりガイドされて送られ、プラテン４２とサーマルヘッド１の間を平行に通過する。サーマルヘッド１は、複数の発熱抵抗体１２がインクリボン３２に平行に接触するように、水平な状態から所定の圧接角度θ’で傾斜させた姿勢を保持する。そして、駆動ＩＣ２１により複数の発熱抵抗体１２を選択的に通電することにより、インクリボン３２を局所的に加熱して該インクリボン３２のインクを感熱紙に転写させ、プラテン４２上に位置する感熱紙３１に文字や画像などを印刷する。サーマルヘッド１のインクリボン３２に対する圧接角度θ’は１〜３０°程度の範囲とする。ここで、図２の矢印方向は感熱紙３１及びインクリボン３２の送り方向である。インクリボン３２は、数μｍ〜数十μｍと薄くて剛性が小さいため、サーマルヘッド１とプラテン４２の間に送り込まれる前（媒体圧接部１１ｃ上の耐磨耗保護層１４と圧接する前）の段階で、送りローラ４１との接触等によりしわが生じてしまう。図２ではインクリボン３２に発生したしわを波線で示す。このしわが生じたインクリボン３２は、耐磨耗保護層１４を介し媒体圧接部１１ｃで圧接されることによって伸長され、しわのない状態で素子対応部１１ｂへ送られる。上述したように媒体圧接部１１ｃの曲率半径φ２を素子対応部１１ｂよりも大きく、且つ、その長さ寸法Ｌを０．２ｍｍ以上としたことで、媒体圧接部１１ｃがインクリボン３２を圧接する範囲を十分に確保でき、インクリボン３２を素子対応部１１ｂに送出する間にインクリボン３２のしわを解消することができる。これにより、印刷画像にインクリボン３２のしわが転写されることがなく、高品質印刷が可能となる。 The thermal head 1 having the above configuration is mounted on a photo printer or a thermal printer, and performs printing by applying heat generated by the heating resistor 12 to the thermal paper 31 (print medium) or the ink ribbon 32. FIG. 2 is a schematic diagram for explaining a printing operation by the thermal head 1. The thermal paper 31 and the ink ribbon 32 are respectively guided by a feed roller 41 and sent in parallel between the platen 42 and the thermal head 1. The thermal head 1 maintains a posture inclined from the horizontal state at a predetermined pressure contact angle θ ′ so that the plurality of heating resistors 12 are in contact with the ink ribbon 32 in parallel. Then, the drive IC 21 selectively energizes the plurality of heating resistors 12 to locally heat the ink ribbon 32 to transfer the ink on the ink ribbon 32 onto the thermal paper, and the thermal sensitivity located on the platen 42. A character, an image, or the like is printed on the paper 31. The pressure contact angle θ ′ of the thermal head 1 with respect to the ink ribbon 32 is in the range of about 1 to 30 °. Here, the arrow direction in FIG. 2 is the feeding direction of the thermal paper 31 and the ink ribbon 32. Since the ink ribbon 32 is as thin as several μm to several tens of μm and has low rigidity, it is before being fed between the thermal head 1 and the platen 42 (before being pressed against the wear-resistant protective layer 14 on the medium pressure contact portion 11c). At the stage, wrinkles occur due to contact with the feed roller 41 or the like. In FIG. 2, wrinkles generated in the ink ribbon 32 are indicated by wavy lines. The ink ribbon 32 in which the wrinkles are generated is stretched by being pressed by the medium pressure contact portion 11c through the wear-resistant protective layer 14, and is sent to the element corresponding portion 11b without wrinkles. As described above, the radius of curvature φ2 of the medium pressure contact portion 11c is larger than that of the element corresponding portion 11b, and the length L is 0.2 mm or more, so that the medium pressure contact portion 11c is in pressure contact with the ink ribbon 32. Can be secured sufficiently, and the wrinkles of the ink ribbon 32 can be eliminated while the ink ribbon 32 is sent to the element corresponding portion 11b. Thereby, wrinkles of the ink ribbon 32 are not transferred to the print image, and high-quality printing is possible.
次に、図３〜図５を参照し、図１に示すサーマルヘッド１の製造方法の一実施形態について説明する。 Next, an embodiment of a method for manufacturing the thermal head 1 shown in FIG. 1 will be described with reference to FIGS.
先ず、図３に示すように、ヘッド基板１０の表面領域を仮想的に分割し、複数並列したヘッド形成領域Ｈを設定する。 First, as shown in FIG. 3, the surface region of the head substrate 10 is virtually divided, and a plurality of head formation regions H arranged in parallel are set.
次に、図４に示すように、ヘッド基板１０の各ヘッド形成領域Ｈ毎に、例えばガラスなどの高断熱材料から蓄熱層１１を形成し、焼成する。蓄熱層１１は、スクリーン印刷により、基板表面からの距離が最大となる頂点位置Ｐを境にして素子対応部１１ｂ及び媒体圧接部１１ｃを備えた凸形状部と、媒体圧接部１１ｃから各ヘッド形成領域の一端部側へ延出させた均一膜厚の平坦部１１ａとを有する形状で形成される。素子対応部１１ｂは頂点位置Ｐからヘッド形成領域Ｈの端部側に形成し、媒体圧接部１１ｃは頂点位置Ｐと平坦部１１ａの間に形成する。このとき、素子対応部１１ｂの曲面は３ｍｍ未満の第１の曲率半径φ１で形成し、媒体圧接部１１ｃの曲面は、第１の曲率半径φ１よりも大きい第２の曲率半径φ２（φ１＜φ２）で形成する。第２の曲率半径φ２は、具体的には３ｍｍ以上とすることが好ましく、図６に示すように∞（平坦面）であってもよい。図１に示す蓄熱層１１は、素子対応部１１ｂの曲率半径φ１が２．５ｍｍ、媒体圧接部１１ｃの曲率半径φ２が３．５ｍｍである。さらに、媒体圧接部１１ｃは、サーマルヘッド１とインクリボンの接触範囲を十分に確保できるように、印刷媒体の走行方向（図２の矢印方向）における長さ寸法Ｌを０．２ｍｍ以上として形成する。また、平坦部１１ａは媒体圧接部１１ｃよりも表面位置を低くして形成し、平坦部１１ａの表面位置と媒体圧接部１１ｃの最高表面位置（頂点位置Ｐ）との間に段差αを形成する。 Next, as shown in FIG. 4, for each head formation region H of the head substrate 10, a heat storage layer 11 is formed from a highly heat insulating material such as glass and fired. The heat storage layer 11 is formed by screen printing to form a head from the convex portion having the element corresponding portion 11b and the medium pressure contact portion 11c at the apex position P where the distance from the substrate surface is maximum, and the medium pressure contact portion 11c. It is formed in a shape having a flat portion 11a having a uniform film thickness extending toward one end of the region. The element corresponding portion 11b is formed on the end side of the head formation region H from the vertex position P, and the medium pressure contact portion 11c is formed between the vertex position P and the flat portion 11a. At this time, the curved surface of the element corresponding portion 11b is formed with a first curvature radius φ1 of less than 3 mm, and the curved surface of the medium pressure contact portion 11c is a second curvature radius φ2 (φ1 <φ2) that is larger than the first curvature radius φ1. ). Specifically, the second radius of curvature φ2 is preferably 3 mm or more, and may be ∞ (flat surface) as shown in FIG. In the heat storage layer 11 shown in FIG. 1, the radius of curvature φ1 of the element corresponding portion 11b is 2.5 mm, and the radius of curvature φ2 of the medium pressure contact portion 11c is 3.5 mm. Further, the medium pressure contact portion 11c is formed with a length dimension L in the running direction of the print medium (the arrow direction in FIG. 2) of 0.2 mm or more so that a sufficient contact range between the thermal head 1 and the ink ribbon can be secured. . Further, the flat portion 11a is formed with a lower surface position than the medium pressure contact portion 11c, and a step α is formed between the surface position of the flat portion 11a and the highest surface position (vertex position P) of the medium pressure contact portion 11c. .
続いて、各蓄熱層１１の上に、抵抗層１２ａ及び電極１３を連続成膜する。成膜にはスパッタや蒸着法を用いることができる。抵抗層１２ａはＴａ2Ｎ又はＴａ−ＳｉＯ2等のサーメット材料により形成し、電極１３は例えばＣｒ等の電極材料により形成する。成膜後は、フォトリソグラフィ技術を用いて、各電極１３のパターン形状を規定し、蓄熱層１１の素子対応部１１ｂ上であって頂点位置Ｐから所定角度θだけ偏向させた位置に存在する電極１３を除去して開放部１３ｃを形成する。この工程により、図５に示すように、電極１３は開放部１３ｃを介して共通電極１３ａと複数の個別電極１３ｂとに分離し、開放部１３ｃから露出している抵抗層１２ａがそれぞれ発熱抵抗体１２となる。発熱抵抗体１２は、電極１３の開放部１３ｃと同様に、蓄熱層１１の素子対応部１１ｂの上に位置しており、且つ、頂点位置Ｐから所定角度θだけ偏向している。ここで、上述したように蓄熱層１１の素子対応部１１ｂは第１の曲率半径φ１で形成されており、頂点位置Ｐに存在する抵抗層１２ａの表面高さ（基板表面からの最短距離）と発熱抵抗体１２の表面高さ（基板表面からの最短距離）はほぼ同等となっている。よって、発熱抵抗体１２が頂点位置Ｐからずれた位置に配置されていても、サーマルヘッドを傾斜姿勢で保持したときに発熱抵抗体１２とインクリボン３２の接触は良好に保たれる。また、電極１３のパターン形状及び開放部１３ｃを精度良く形成することができ、発熱抵抗体１２の抵抗値がばらつくこともない。図示されていないが、発熱抵抗体１２は、図５の紙面に垂直な方向に微小間隔をおいて整列している。 Subsequently, the resistance layer 12 a and the electrode 13 are continuously formed on each heat storage layer 11. Sputtering or vapor deposition can be used for film formation. Resistive layer 12a is formed by a cermet material such as Ta 2 N or Ta-SiO 2, electrodes 13 are formed by the electrode material such as Cr or the like. After film formation, the pattern shape of each electrode 13 is defined using a photolithography technique, and the electrode exists on the element corresponding portion 11b of the heat storage layer 11 and is deflected by a predetermined angle θ from the apex position P. 13 is removed to form an opening 13c. By this step, as shown in FIG. 5, the electrode 13 is separated into a common electrode 13a and a plurality of individual electrodes 13b through the open portion 13c, and the resistance layers 12a exposed from the open portion 13c are respectively heating resistors. 12 The heating resistor 12 is located on the element corresponding portion 11b of the heat storage layer 11 and is deflected from the apex position P by a predetermined angle θ, similarly to the open portion 13c of the electrode 13. Here, as described above, the element corresponding portion 11b of the heat storage layer 11 is formed with the first curvature radius φ1, and the surface height of the resistance layer 12a existing at the apex position P (the shortest distance from the substrate surface) and The surface height (the shortest distance from the substrate surface) of the heating resistor 12 is substantially the same. Therefore, even when the heating resistor 12 is disposed at a position deviated from the apex position P, the contact between the heating resistor 12 and the ink ribbon 32 is kept good when the thermal head is held in an inclined posture. Further, the pattern shape of the electrode 13 and the open portion 13c can be formed with high accuracy, and the resistance value of the heating resistor 12 does not vary. Although not shown in the figure, the heating resistors 12 are aligned at a minute interval in a direction perpendicular to the paper surface of FIG.
電極１３に開放部１３ｃを形成した後は、各個別電極１３ｂのボンディング接続部を除いて全面的に耐磨耗保護層１４を成膜すると、ヘッド基板１上には複数並列に並んだサーマルヘッド構造が得られる。そして、各ヘッド形成領域Ｈごとにヘッド基板１を切断し、１つのヘッド基板１０上に１つのヘッド構造を有する個々のヘッド基板１を得る。切断後のヘッド基板１０の大きさは長さ寸法３ｍｍ、幅寸法１１０ｍｍ程度であり、従来のヘッド基板（長さ寸法６ｍｍ、幅寸法１１０ｍｍ）よりも大幅に小型化されている。これにより、図３に示したウエハ状のヘッド基板１０から生産可能なヘッド個数は増大し、低コスト化を図れる。 After the open portion 13c is formed on the electrode 13, when a wear-resistant protective layer 14 is formed on the entire surface except for the bonding connection portion of each individual electrode 13b, a plurality of thermal heads arranged in parallel on the head substrate 1 are formed. A structure is obtained. Then, the head substrate 1 is cut for each head formation region H to obtain individual head substrates 1 having one head structure on one head substrate 10. The size of the head substrate 10 after cutting is approximately 3 mm in length and 110 mm in width, and is significantly smaller than the conventional head substrate (6 mm in length and 110 mm in width). As a result, the number of heads that can be produced from the wafer-like head substrate 10 shown in FIG. 3 increases, and the cost can be reduced.
続いて、ヘッド基板１０とは別個のプリント回路基板２０を用意し、このプリント回路基板２０の一端部に、複数の発熱抵抗体１２への通電制御を行なう駆動ＩＣ２１を半田付け等で搭載した後に、例えばワイヤーボンディングにより駆動ＩＣ２１を、ヘッド基板１０上の複数の個別電極１３ｂ及びプリント回路基板２０上の回路にそれぞれ接続する。そして、ヘッド基板１０の耐磨耗保護層１４の表面から駆動ＩＣ２２を含むプリント回路基板２０の表面を覆う封止樹脂２２を形成し、この封止樹脂２２により駆動ＩＣ２１を封止する。この封止樹脂２２により、ヘッド基板１０とプリント回路基板２０は接着されて一体となる。以上により、図１に示すサーマルヘッド１が完成する。本実施形態では、上述したように蓄熱層１１が媒体圧接部１１ｃよりも表面位置が低い平坦部１１ａを有しているので、平坦部１１ａと媒体圧接部１１ｃの間に段差αができ、ヘッド基板１が小型化して頂点位置Ｐから駆動ＩＣ２１までの距離間隔が狭くなっても、駆動ＩＣ２１がインクリボンに当接する虞がない。 Subsequently, after preparing a printed circuit board 20 separate from the head substrate 10 and mounting a driving IC 21 for controlling energization to the plurality of heating resistors 12 on one end of the printed circuit board 20 by soldering or the like. For example, the drive IC 21 is connected to the plurality of individual electrodes 13b on the head substrate 10 and the circuit on the printed circuit board 20 by wire bonding, for example. Then, a sealing resin 22 that covers the surface of the printed circuit board 20 including the driving IC 22 is formed from the surface of the wear-resistant protective layer 14 of the head substrate 10, and the driving IC 21 is sealed with the sealing resin 22. The sealing substrate 22 bonds the head substrate 10 and the printed circuit board 20 together. Thus, the thermal head 1 shown in FIG. 1 is completed. In this embodiment, since the heat storage layer 11 has the flat portion 11a whose surface position is lower than that of the medium pressure contact portion 11c as described above, a step α is formed between the flat portion 11a and the medium pressure contact portion 11c. Even if the substrate 1 is downsized and the distance from the apex position P to the drive IC 21 is reduced, there is no possibility that the drive IC 21 contacts the ink ribbon.
以上では、ヘッド基板１０とプリント基板２０を別々に備えたサーマルヘッドに本発明を適用した実施形態について説明したが、図７に示すように、ヘッド基板１０とプリント基板２０を１つにした基板１０’として備えてもよい。本実施形態のようにヘッド基板１０とプリント基板２０を別々としたほうがヘッド基板１０の取個数（１枚のウエハ状の基板から生産できる個数）を増大させることができ、さらなる低コスト化が期待できる。また本実施形態では、プリント基板２０上に駆動ＩＣ２１を設けているが、駆動ＩＣ２１はヘッド基板１０上に設けてもよい。駆動ＩＣ２１をヘッド基板１０上に設ける場合には、耐磨耗保護層１４の上に各種回路を形成すると共に駆動ＩＣ２１を配置することができる。 In the above, the embodiment in which the present invention is applied to the thermal head provided with the head substrate 10 and the printed board 20 separately has been described. However, as shown in FIG. 7, the head board 10 and the printed board 20 are combined into one. It may be provided as 10 ′. If the head substrate 10 and the printed circuit board 20 are separated as in the present embodiment, the number of head substrates 10 to be taken (number that can be produced from one wafer-like substrate) can be increased, and further cost reduction is expected. it can. In the present embodiment, the drive IC 21 is provided on the printed circuit board 20, but the drive IC 21 may be provided on the head substrate 10. When the driving IC 21 is provided on the head substrate 10, various circuits can be formed on the wear-resistant protective layer 14 and the driving IC 21 can be disposed.
１ サーマルヘッド
１０ ヘッド基板
１１ 蓄熱層
１１ａ 平坦部
１１ｂ 素子対応部
１１ｃ 媒体圧接部
１２ 発熱抵抗体
１２ａ 抵抗層
１３ 電極
１３ａ 共通電極
１３ｂ 個別電極
１３ｃ 開放部
１４ 耐磨耗保護層
２０ プリント回路基板
２１ 駆動ＩＣ
２２ 封止樹脂
３１ 感熱紙（印刷媒体）
３２ インクリボン
４１ 送りローラ
４２ プラテン
DESCRIPTION OF SYMBOLS 1 Thermal head 10 Head board | substrate 11 Thermal storage layer 11a Flat part 11b Element corresponding | compatible part 11c Medium pressure contact part 12 Heating resistor 12a Resistance layer 13 Electrode 13a Common electrode 13b Individual electrode 13c Opening part 14 Wear-resistant protective layer 20 Printed circuit board 21 Drive IC
22 Sealing resin 31 Thermal paper (printing medium)
32 Ink ribbon 41 Feed roller 42 Platen
Claims (9)
前記蓄熱層は、前記頂点位置を境に、前記複数の発熱抵抗体が形成されている側の素子対応部と前記複数の発熱抵抗体が形成されていない側の媒体圧接部とを有し、この媒体圧接部の曲率半径が素子対応部の曲率半径よりも大きいことを特徴とするサーマルヘッド。 A heat storage layer having a convex shape with a uniform cross section having a vertex position where the distance from the substrate surface is maximum on a flat head substrate, and a plurality of heat storage layers arranged in a row on the heat storage layer while being shifted from the vertex position A thermal head that includes a plurality of heating resistors and an electrode that energizes the plurality of heating resistors, and performs a printing operation by bringing the plurality of heating resistors into contact with the print medium substantially in parallel.
The heat storage layer has an element corresponding portion on the side where the plurality of heating resistors are formed and a medium pressure contact portion on the side where the plurality of heating resistors are not formed, with the apex position as a boundary, A thermal head characterized in that the radius of curvature of the medium pressure contact portion is larger than the radius of curvature of the element corresponding portion.
前記蓄熱層の上に抵抗層と電極を全面的に形成する工程と、
前記電極に、前記蓄熱層の素子対応部の上であって前記頂点位置からずらした位置に開放部を形成し、この開放部から前記抵抗層を露出させて複数の発熱抵抗体を形成する工程と、
を有することを特徴とするサーマルヘッドの製造方法。 The flat head substrate has a vertex position where the distance from the substrate surface is maximum, and the element corresponding portion having the first radius of curvature is greater than the first radius of curvature with the vertex position as a boundary. Forming a convex heat storage layer comprising a medium pressure contact portion having a second radius of curvature;
Forming a resistance layer and an electrode on the entire surface of the heat storage layer;
Forming a plurality of heating resistors on the electrode by forming an open portion on the element corresponding portion of the heat storage layer at a position shifted from the apex position and exposing the resistance layer from the open portion; When,
A method of manufacturing a thermal head, comprising:
9. The thermal head manufacturing method according to claim 5, wherein a surface region of the head substrate is divided into a plurality of virtually formed head formation regions, and each of the head formation regions includes the heat storage layer, A method for manufacturing a thermal head, comprising: forming a heating resistor and the electrode; and cutting the head substrate for each head formation region.
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| JP2003413542A JP2005169855A (en) | 2003-12-11 | 2003-12-11 | Thermal head and manufacturing method therefor |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005262828A (en) * | 2004-03-22 | 2005-09-29 | Toshiba Hokuto Electronics Corp | Thermal print head |
| EP1808299A2 (en) | 2006-01-12 | 2007-07-18 | Alps Electric Co., Ltd. | Thermal head and manufacturing method thereof |
| JP2018065254A (en) * | 2016-10-17 | 2018-04-26 | 東芝ホクト電子株式会社 | Thermal print head and thermal printer |
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2003
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005262828A (en) * | 2004-03-22 | 2005-09-29 | Toshiba Hokuto Electronics Corp | Thermal print head |
| EP1808299A2 (en) | 2006-01-12 | 2007-07-18 | Alps Electric Co., Ltd. | Thermal head and manufacturing method thereof |
| JP2018065254A (en) * | 2016-10-17 | 2018-04-26 | 東芝ホクト電子株式会社 | Thermal print head and thermal printer |
| JP7031815B2 (en) | 2016-10-17 | 2022-03-08 | 東芝ホクト電子株式会社 | Thermal printheads and thermal printers |
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