JP4666972B2 - Thermal head and thermal printer using the same - Google Patents

Description

  The present invention relates to a thermal head incorporated in a printer mechanism such as a word processor or a facsimile, and a thermal printer using the thermal head.

  Conventionally, thermal heads have been used as printing devices such as facsimiles and video printers.

  In such a conventional thermal head, for example, as shown in FIG. 5, a glaze layer 12 is formed on the upper surface of the substrate 11 over substantially the entire area, and a part of the glaze layer 12 extends in a band shape. A plurality of heating elements 13 each having a rectangular shape are linearly arranged, and individual electrode wirings 14 and common electrode wirings 15 are connected to both ends of each heating element 13 and covered with a surface protective layer 16. Things are known.

  When printing using this thermal head, a recording medium such as thermal paper is conveyed in a direction perpendicular to the arrangement direction of the heating elements 13 while being in sliding contact with the surface protective layer 16, and based on print data from the outside. A plurality of heat generating elements 13 are selectively heated individually, and a process of transferring the heat to the recording medium is performed.

  The heating element 13 and the individual electrode wiring 14 described above are conventionally known thin film forming techniques, specifically, a resistor layer made of an electric resistance material constituting the heating element 13 and a metal constituting the individual electrode wiring 14. A metal layer made of a material is sequentially laminated on the glaze layer 12 by using a conventionally known sputtering method, CVD method, vapor deposition method, printing method, or the like, and the laminated body is adopted by a conventionally well-known photolithography technique and etching technique. Thus, it is formed by processing into a predetermined pattern. At that time, the resistor layer and the metal layer are subjected to wiring patterning according to the shapes of the heating element 13 and the individual electrode wiring 14.

The surface protective layer 16 covering the heating element 13 and the individual electrode wiring 14 is for preventing the heating element 13 and the individual electrode wiring 14 from being corroded by moisture in the atmosphere. It is formed to a thickness of 3 μm to 10 μm on the substrate 11 on which the individual electrode wiring 14 is provided.
JP-A-11-91148

  By the way, in general, when using a thermal printer, foreign matter may come into the surface of the thermal head or the surface of the recording medium.

  When the thermal printer is driven, the foreign matter is conveyed along with the recording medium from the upstream side to the downstream side of the individual electrode wiring 14 by the platen roller. As a result, the foreign matter is caught between the heating element 13 and the platen roller. In some cases, scratches may occur in the surface protective layer.

  When such foreign matter is repeatedly bitten, the surface protective layer 16 protecting the heat generating element 13 is cracked, so that the sealing property of the surface protective layer 16 is impaired and the heat generating element 13 is lost. Otherwise, the individual electrode wiring 14 is oxidized and damaged. As a result, the heat conduction to the recording medium is partially reduced at the damaged portion of the heating element or the like, and the printing formed on the recording medium becomes unclear, leading to a reduction in printing quality.

  The foreign matter that causes scratches on the heat generating element 13 has a maximum diameter of about 5 μm to 20 μm.

  The present invention has been devised in view of the above-described drawbacks, and an object of the present invention is to provide a thermal head and a thermal printer using the thermal head in which the print quality does not deteriorate.

The thermal head of the present invention includes a plurality of heating elements arranged on the upper surface of the substrate, individual electrode wirings individually connected to the heating elements, and a surface protection layer covering the heating elements and the individual electrode wirings. In the thermal head that performs the recording operation while transporting the recording medium onto the heating element, the step portion is formed on the surface protective layer so that the upstream surface in the recording medium transport direction is low and the downstream surface is high. thereby forming a step portion, the end edges of the stepped portion when viewed in plan has the shape of a zigzag, the surface of low surface protective layer side is recorded between the individual electrode wiring adjacent It is characterized in that it has entered the downstream side in the conveyance direction of the medium.

In the above thermal head of the present invention, the stepped portion may be formed by changing the thickness of the surface protective layer.

In the above thermal head of the present invention, the substrate, which has a glaze layer in a region where the heating elements are formed, the step portion may be formed by the thickness of the glaze layer.

  According to the thermal head of the present invention, even when foreign matter has been transported on the surface protective layer that is directly above the individual electrode wiring together with the recording medium transported by the platen roller when the thermal printer is driven, Since the foreign matter is blocked by the formed step portion, the foreign matter can be prevented from entering the heating element side from the individual electrode wiring.

  In addition, the step portion has a zigzag shape when viewed from above, and the lower surface of the surface protective layer enters the downstream side between the adjacent individual electrode wirings. For this reason, the foreign matter present on the individual electrode wiring is guided to the left and right spacing regions by being divided into the left and right in the width direction of the individual electrode wiring.

  Therefore, foreign matter can be prevented from being caught between the heating element and the platen roller, and scratches will not be generated. Therefore, the sealing property of the surface protective layer immediately above the heating element is improved, thereby improving the print quality. Can be provided.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a plan view of a thermal head according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the thermal head of FIG. 1. In these thermal heads, a glaze layer 2 is formed on a substrate 1. On the layer 2, a plurality of heating elements 3, individual electrode wirings 4, a surface protective layer 6, etc. are provided.

  The substrate 1 is formed in a rectangular shape by various materials such as an insulating material such as alumina ceramics, single crystal silicon having an oxide film deposited on the surface, and the glaze layer 2, the heating element 3, and the individual are formed on the upper surface thereof. It functions as a support base material that supports the electrode wiring 4 and the surface protective layer 6.

  When the substrate 1 is made of alumina ceramics, for example, an appropriate organic solvent or solvent is added to and mixed with ceramic raw material powders such as alumina, silica, and magnesia to form a slurry, and this is made into a conventionally known doctor. A ceramic green sheet is obtained by adopting a blade method, a calender roll method, or the like, and thereafter, the green sheet is punched into a predetermined shape and then fired at a high temperature (about 1600 ° C.).

  A glaze layer 2 is formed in a strip shape on the upper surface of the substrate 1.

  The glaze layer 2 has an action of storing heat generated by the heat generating element 3 inside to maintain good thermal responsiveness of the thermal head.

  When such a glaze layer 2 is made of, for example, glass, a glass paste obtained by adding and mixing an appropriate organic solvent, organic binder, or the like to glass powder is applied to a predetermined upper surface of the substrate by a conventionally known screen printing method or the like. It is formed by applying to a region and processing it into a predetermined shape by employing a conventionally well-known photolithography technique, and then heating it at a high temperature of 850 ° C. to 950 ° C. for a predetermined time.

  Further, the plurality of heating elements 3 deposited on the top surface of the top of the glaze layer 2 are linearly deposited and arranged at a density of 300 dpi (dots per inch) through a spacing region s described later. Each is composed of a resistor layer made of a TaSiO-based, TaSiNO-based, TiSiO-based, TiSiCO-based, or NbSiO-based electrical resistance material.

  Further, each of the heating elements 3 is formed to have a rectangular shape (for example, a width of 110 μm in the conveyance direction of the recording medium and a width of 65 μm in the direction perpendicular to the direction), and individual electrode wirings 4 connected to both ends thereof. When the power supply is applied via the common electrode wiring 5, Joule heat is generated, and a predetermined temperature (250 ° C. to 400 ° C.) necessary for forming a print on a recording medium such as thermal paper is obtained.

  The individual electrode wiring 4 connected to one end of the heating element 3 is extended from the one end side of the heating element 3 substantially perpendicular to the heating element row by a metal layer made of a metal material such as aluminum or copper. And functions as a connection wiring connected to a driver IC (not shown).

  The individual electrode wirings 4 are separated from each other via an interval region s having a predetermined interval.

  The common electrode wiring 5 is made of a metal material such as aluminum or copper, and functions as a power supply wiring for supplying power to the heating element 3. A voltage of about 24 V is normally applied to the heating element 3 by the common electrode wiring 5.

  Such a heating element 3, the individual electrode wiring 4 and the common electrode wiring 5 are manufactured by employing a conventionally well-known thin film forming technique, for example, sputtering, a photolithography technique or the like. Specifically, first, a resistance material such as TaSiO and a metal material such as aluminum are sequentially laminated on the upper surface of the glaze layer 2 by sputtering, which is conventionally known, to form a laminate composed of a resistance layer and a metal layer (resistance layer thickness 0). .05 .mu.m to 0.2 .mu.m and metal layer thickness 0.1 .mu.m to 1.3 .mu.m) is formed, and this is finely processed by a conventionally known photolithography technique and etching technique, thereby patterning the resistor layer and the metal layer. Thus, the heating element 3, the individual electrode wiring 4 and the common electrode wiring 5 are formed.

  On the other hand, a surface protective layer 6 is deposited on the heating element 3 and the individual electrode wiring 4 described above, and these are commonly covered by the surface protective layer 6.

  The surface protective layer 6 is for preventing the heating element 3 and the individual electrode wiring 4 from being corroded by moisture in the atmosphere, and is provided on the substrate 1 on which the heating element 3 and the individual electrode wiring 4 are provided. To a thickness of 10 μm to 50 μm.

  Further, the surface protective layer 6 is provided with a stepped portion 6X in a region pressed by the platen roller R1 and in which the individual electrode wiring 4 is formed. The stepped portion 6X has a lower upstream surface (a lower surface 6A of the surface protective layer 6) in the recording medium transport direction than the surface protective layer 6 and a lower surface (a higher surface of the surface protective layer 6). The surface 6B) is formed to be high.

  For this reason, even when foreign matter is transported on the surface protective layer 6 that is directly above the individual electrode wiring 4 together with the recording medium transported by the platen roller R1 when the thermal printer is driven, it is formed on the surface protective layer 6 described above. Since the foreign matter is blocked by the stepped portion 6X, it is possible to suppress the foreign matter from entering the heating element 3 side from the individual electrode wiring 4.

  In addition, as shown in FIG. 1, the step portion 6X has a zigzag at the end of the step portion 6X when viewed in plan, and the lower surface 6A of the surface protective layer 6 is adjacent to the adjacent individual portion. It penetrates to the downstream side between the electrode wirings 4.

  As a result, the foreign matter present on the individual electrode wiring 4 is divided into left and right in the width direction of the individual electrode wiring 4 and is guided to the left and right spacing regions s.

  Therefore, it is possible to suppress foreign matter from being caught between the heating element 3 and the platen roller R1, and since scratches are not generated, the sealing property of the surface protective layer 6 immediately above the heating element 3 is improved. Thereby, it is possible to provide a thermal head in which the print quality does not deteriorate.

  Even if the foreign matter staying in the interval region s passes over the step portion 6X and is transported to the downstream side in the transport direction of the recording medium, it is transported to the region between the adjacent heat generating elements. The surface protective layer 6 can be prevented from being damaged.

  Further, the height of the step of the step portion 6X may be the same as or higher than the maximum diameter of the foreign matter, and is specifically set to 10 μm to 15 μm.

  For this reason, in this invention, in order to ensure the height of the level | step-difference part 6X, the thickness of the surface protective layer 6 which was 3 micrometers-10 micrometers conventionally is set to 10 micrometers-50 micrometers.

  The wall of the stepped portion 6X has a steep precipitous shape rather than a gentle slope in the height direction, so that foreign matter can be guided more reliably.

  And the level | step-difference part 6X of the surface protective layer 6 mentioned above is produced as follows.

  First, a thin film having a substantially constant thickness is formed by a conventionally known thin film forming technique (sputtering method, vapor deposition method, CVD method, etc.) or a thick film forming technique (screen printing method, dispenser method, etc.).

  Next, the region closer to the heating element so that the thickness is different between the region closer to the heating element 3 than the region where the thin film level difference portion 6X is to be formed and the region closer to the heating element 3. Photoresist is applied only to the film, and the film thickness on the side far from the heating element 3 is thinned by, for example, etching. Thereby, the surface protective layer 6 is formed.

  Thus, the above-described thermal head selectively causes Joule heating of the plurality of heating elements 3 individually based on image data from the outside while conveying a recording medium such as thermal paper in a direction orthogonal to the arrangement of the heating elements 3. At the same time, the heat is transmitted to the recording medium on the heating element 3 to form a print, thereby functioning as a thermal head.

  In the thermal printer in which the thermal head T as described above is incorporated, as shown in FIG. 4, the platen roller R1 and the conveyance roller R2 are used as conveyance means for conveying the recording medium K onto the heating element 3 of the thermal head T. Etc. are arranged.

  The platen roller R1 is a cylindrical member in which butadiene rubber or the like is wound around the outer periphery of a shaft core made of a metal such as SUS so as to have a thickness of about 3 mm to 15 mm, and is rotatably supported on the heating element 3 of the thermal head T. Then, the recording medium K is conveyed in the direction orthogonal to the arrangement of the heating elements 3 by the rotation.

  Further, the surface of the platen roller R1 is in contact with the surface protective layer 6 of the thermal head T via the recording medium K, and the recording medium K is pressed against the surface of the surface protective layer 6 on the heating element 3 in the contact area. is doing.

  At this time, the platen roller R1 locates the stepped portion 6X of the surface protective layer 6 in the pressing area where the thermal head T is pressed via the recording medium K, so that the foreign matter is reliably generated by the pressing force of the platen roller R1. Can be guided from the individual electrode wiring 4 to the interval region s.

  On the other hand, the outer periphery of the transport roller R2 is formed of metal, rubber, or the like, and is arranged separately from the thermal head T in the transport direction upstream and downstream of the recording medium K. These transport rollers R2 and The platen roller R1 supports the traveling of the recording medium K.

  At the same time, a plurality of heat generating elements 3 are selectively joule-heated as the driver IC (not shown) is driven, and these heats are transmitted to the recording medium K through the surface protective layer 6 to form a predetermined print. The

  In addition, this invention is not limited to the form mentioned above, A various change and improvement are possible in the range which does not deviate from the summary of this invention.

For example, in the above-described embodiment, the step portion 6X is formed by changing the thickness of the surface protective layer 6. However, instead of this, as shown in FIG. the stepped portion 6 X provided by changing, thereby the surface of the glaze layer 2 on the surface protection was applied to the layer 6 may have a stepped portion 6X as the result.

  When the glaze layer 2 is a convex partial glaze, a stepped portion may be formed by the peripheral edge of the glaze layer 2, that is, the boundary between the glaze layer 2 and the substrate 1.

(A) is a plan view of a thermal head according to an embodiment of the present invention, and (B) is a partially enlarged plan view of a stepped portion forming region. FIG. 2 is a cross-sectional view of the thermal head of FIG. It is sectional drawing of the thermal head which concerns on other embodiment of this invention. 1 is a schematic cross-sectional view of a thermal printer according to an embodiment of the present invention. It is sectional drawing of the conventional thermal head.

Explanation of symbols

T ... thermal head R1 ... platen roller R2 ... conveying roller 1 ... substrate 2 ... glaze layer 2X ... step part 3 of the glaze layer ... heating element 4 ... individual conduction Layer 5 ... Common conductive layer 6 ... Surface protective layer 6X ... Step portion 6A of the surface protective layer ... Surface 6B on the lower side of the surface protective layer ... Surface s on the higher side of the surface protective layer ... Interval area

Claims (3)

A plurality of heating elements arranged on the upper surface of the substrate, individual electrode wirings individually connected to the heating elements, and a surface protection layer covering the heating elements and the individual electrode wirings, and recording on the heating elements In the thermal head that performs the recording operation while conveying the medium,
A stepped portion is formed on the surface protective layer so that the upstream surface in the recording medium conveyance direction is low and the downstream surface is high, and the stepped portion is an end of the stepped portion when viewed in plan. side has the shape of a zigzag, the thermal head surface of low surface protective layer side, characterized in that has entered to the downstream side in the transport direction of the recording medium between the individual electrode wiring adjacent. The step portion is a thermal head according to claim 1, characterized in that it is formed by changing the thickness of the surface protective layer. The substrate, which has a glaze layer in a region where the heating elements are formed, the step portion, the thermal head according to claim 1, characterized in that it is formed by the thickness of the glaze layer.

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