CN111716917A

CN111716917A - Thermal print head and method of manufacturing thermal print head

Info

Publication number: CN111716917A
Application number: CN202010185328.0A
Authority: CN
Inventors: 小林大辉
Original assignee: Rohm Co Ltd
Current assignee: Rohm Co Ltd
Priority date: 2019-03-19
Filing date: 2020-03-17
Publication date: 2020-09-29
Anticipated expiration: 2040-03-17
Also published as: JP2020151903A; CN111716917B; JP7245684B2

Abstract

The invention provides a thermal print head and a method of manufacturing the thermal print head. A thermal print head includes: a substrate having a major face; a glaze which is formed on a main surface of the substrate so as to extend in the main scanning direction, and has an arc-shaped cross-sectional shape cut by a plane orthogonal to the main scanning direction; a resistor layer formed on the glaze so as to extend in the main scanning direction; an electrode layer comprising a glaze electrode layer formed on the glaze; and a protective layer covering the resistor layer and the electrode layer. The protective layer has a first portion formed on the resistor layer and having a first surface having a first height from the main surface, and a second portion arranged on a downstream side in the sub-scanning direction from the first portion and having a second surface arranged at a position having a height greater than or equal to the first height from the main surface. The invention can make the printing waste difficult to retain.

Description

Thermal print head and method of manufacturing thermal print head

Technical Field

The present invention relates to a thermal print head and a method of manufacturing the thermal print head.

Background

The thermal head is mounted on, for example, a thermal printer that prints on thermal recording paper. As an example of a thermal head, a thermal head disclosed in japanese patent laid-open No. 2016-: the resistor includes a substrate, a partial glaze formed on a main surface of the substrate, an electrode layer and a resistor layer formed on the partial glaze, and a protective layer covering the electrode layer and the resistor layer. The protective layer has a convex portion formed at a portion where the resistor layer is formed. In the thermal head, the resistor layer energized through the electrode layer generates heat, and thereby printing on thermal recording paper is enabled.

Disclosure of Invention

Technical problem to be solved by the invention

However, printing waste is generated when the thermal recording paper is printed. The thermal recording paper is printed by being melted by heat from the resistor layer and then dried. Since the time from melting to drying of the thermal recording paper is short, printing waste generated when the thermal recording paper is printed adheres to a portion on the downstream side in the sub-scanning direction (conveyance direction of the thermal recording paper) with respect to the convex portion of the protective layer. Since the concave portion for preventing the thermal recording paper from coming into contact with the protective layer when the thermal recording paper is conveyed is formed in the convex portion and the portion on the downstream side in the sub-scanning direction from the convex portion, printing waste remains in the concave portion.

The invention aims to provide a thermal print head and a method for manufacturing the thermal print head, wherein printing waste is difficult to retain.

Technical solution for solving technical problem

The thermal print head solving the above technical problem comprises: a substrate having a major face; a glaze which is formed on a main surface of the substrate so as to extend in a main scanning direction, and has an arc-shaped cross-sectional shape cut by a plane orthogonal to the main scanning direction; a resistor layer formed on the glaze so as to extend in the main scanning direction; an electrode layer comprising a glaze electrode layer formed on the glaze; and a protective layer covering the resistor layer and the electrode layer, the protective layer including a first portion formed on the resistor layer and having a first surface having a first height from the main surface, and a second portion arranged on a downstream side in a sub-scanning direction from the first portion and having a second surface arranged at a position having a height from the main surface equal to or greater than the first height.

According to this structure, when, for example, the thermal recording paper is conveyed, the thermal recording paper is in contact between the first surface of the first portion and the second surface of the second portion of the protective layer, whereby printing waste generated when the thermal recording paper is printed on the first surface of the first portion is swept out. Therefore, the printing waste is hard to be retained between the first face of the first portion and the second face of the second portion of the protective layer.

The method for manufacturing the thermal print head for solving the technical problems comprises the following steps: a glaze forming step of forming a glaze on a main surface of a substrate; a glaze electrode layer forming step of forming a glaze electrode layer on the glaze; a resistor layer forming step of forming a resistor layer on the glaze; and a protective layer forming step of forming a protective layer covering the glaze electrode layer and the resistor layer, the protective layer having a first portion and a second portion, the first portion being formed on the resistor layer and having a first surface having a first height from the main surface, the second portion being disposed on a downstream side in a sub-scanning direction from the first portion, the protective layer forming step including an adjustment step of forming a second surface on the second portion, the second surface being disposed at a position where the height from the main surface is equal to or greater than the first height.

According to this structure, when, for example, the thermal recording paper is conveyed, the thermal recording paper contacts between the first surface of the first portion and the second surface of the second portion of the protective layer, whereby printing waste generated when the thermal recording paper is printed on the first surface of the first portion is swept out. Therefore, the printing waste is hard to be retained between the first face of the first portion and the second face of the second portion of the protective layer.

The method for manufacturing the thermal print head for solving the technical problems comprises the following steps: a glaze forming step of forming a glaze on a main surface of a substrate; a glaze electrode layer forming step of forming a glaze electrode layer on the glaze; a resistor layer forming step of forming a resistor layer on the glaze; and a protective layer forming step of forming a protective layer covering the glaze electrode layer and the resistor layer, wherein in the resistor layer forming step, the resistor layer is formed on an upstream side in a sub-scanning direction from a top of the glaze.

According to this structure, the depth of the recess formed between the surface of the first portion and the surface of the second portion of the protective layer becomes shallower compared to a structure in which the resistor layer is formed on top of the glaze. Thereby, when, for example, the thermal recording paper is conveyed, the thermal recording paper contacts between the surface of the first portion and the surface of the second portion of the protective layer, and printing waste generated when the thermal recording paper is printed on the surface of the first portion is swept out. Therefore, the printing waste is difficult to be trapped between the surface of the first portion and the surface of the second portion of the protective layer.

Effects of the invention

The invention can provide a thermal print head in which printing waste is hard to stay and a method for manufacturing the thermal print head.

Drawings

Fig. 1 is a plan view of a thermal head according to a first embodiment.

Fig. 2 is a partially enlarged view of the thermal print head of fig. 1.

Fig. 3 is a sectional view taken along line 3-3 of fig. 1.

Fig. 4 is an enlarged view of the glaze of fig. 3 and its periphery.

Fig. 5 is a sectional view taken along line 5-5 of fig. 4.

Fig. 6 is a flowchart showing a method of manufacturing a thermal head.

Fig. 7A is an explanatory diagram illustrating a manufacturing process of the thermal head.

Fig. 7B is an explanatory diagram illustrating a manufacturing process of the thermal head.

Fig. 7C is an explanatory diagram illustrating a manufacturing process of the thermal head.

Fig. 7D is an explanatory diagram illustrating a manufacturing process of the thermal head.

Fig. 7E is an explanatory diagram illustrating a manufacturing process of the thermal head.

Fig. 7F is an explanatory diagram illustrating a manufacturing process of the thermal head.

Fig. 7G is an explanatory diagram illustrating a manufacturing process of the thermal head.

Fig. 8 is a cross-sectional view showing glaze and its periphery of the thermal head of the comparative example.

Fig. 9 is a plan view showing a glaze and its periphery in the case where thermal recording paper was printed using the thermal print head of the comparative example.

Fig. 10 is a cross-sectional view showing the glaze and the periphery thereof of the thermal head according to the first embodiment.

Fig. 11 is a plan view showing a glaze and its periphery in the case where thermal recording paper is printed by using the thermal print head of the first embodiment.

Fig. 12A is a cross-sectional view showing the glaze and the periphery thereof of the thermal head according to the second embodiment.

Fig. 12B is an enlarged view of the dotted circle of fig. 12A.

Fig. 13 is a plan view showing the glaze of fig. 12A and its periphery.

Fig. 14 is a cross-sectional view showing the glaze and its periphery.

Fig. 15 is a plan view showing a glaze and its periphery in the case where thermal recording paper is printed by using the thermal print head of the second embodiment.

Fig. 16 is a cross-sectional view showing a glaze of a thermal head according to a modification and its periphery.

Fig. 17 is a cross-sectional view showing a glaze of a thermal head according to a modification and its periphery.

Fig. 18 is a cross-sectional view showing a glaze of a thermal head according to a modification and its periphery.

Fig. 19 is a cross-sectional view showing a glaze of a thermal head according to a modification and its periphery.

Fig. 20 is a cross-sectional view showing a glaze of a thermal head according to a modification and its periphery.

Fig. 21 is a cross-sectional view showing a glaze of a thermal head according to a modification and its periphery.

Fig. 22 is a cross-sectional view showing a glaze of a thermal head according to a modification and its periphery.

Detailed Description

Hereinafter, embodiments of the thermal head will be described with reference to the drawings. The embodiments described below are embodiments illustrating a structure and a method for embodying technical ideas, and the materials, shapes, structures, arrangements, dimensions, and the like of the respective constituent members are not limited to the embodiments described below. The following embodiments can incorporate various changes.

In the present specification, the "state in which the component a and the component B are connected" includes: the case where component a is physically directly connected to component B; and the case where the component a and the component B are indirectly connected by other components that do not affect the electrical connection state.

(first embodiment)

Fig. 1 is a plan view of a thermal head 1. The thermal head 1 is mounted on a thermal printer that prints on thermal recording paper, for example, to produce barcode paper and receipts. As shown in fig. 1, the thermal head 1 includes a head main body 1A formed in a rectangular plate shape and a connector 1B attached to the head main body 1A. When the thermal head 1 is incorporated into a thermal printer, the connector 1B is connected to a connector of the thermal printer.

In the following description, when the thermal head 1 is viewed in plan (hereinafter simply referred to as "plan view"), the longitudinal direction of the head main body 1A is referred to as "main scanning direction X", the short-side direction of the head main body 1A is referred to as "sub-scanning direction Y", and the thickness direction of the head main body 1A (the thickness direction of the substrate) is referred to as "thickness direction Z". The thickness direction Z is a direction orthogonal to the main scanning direction X and the sub-scanning direction Y. The sub-scanning direction Y coincides with the conveyance direction of the thermal recording paper in plan view. For convenience, the direction from the back surface 12 to the main surface 11 of the substrate 10 is referred to as "upper", and the direction from the main surface 11 to the back surface 12 is referred to as "lower". The upper and lower sides can be changed according to the posture of the thermal head 1, and thus are not defined as the actual product direction.

A connector 1B is connected to an upstream end of the head main body 1A in the sub-scanning direction Y and to the center in the main scanning direction X. Further, the position of the connector 1B in the main scanning direction X may be arbitrarily changed. For example, the connector 1B may be connected to one end or the other end of the head main body 1A in the main scanning direction X. Further, a plurality of connectors 1B may be connected to the head main body 1A.

As shown in fig. 1 to 3, the head main body 1A includes: substrate 10, glass layer 20, electrode layer 30, resistor layer 40, protective layer 50, and driver IC 61. The head body 1A may have a configuration in which, for example, a base layer made of glass epoxy resin and a wiring layer made of copper (Cu) or the like are laminated in addition to the substrate 10. In fig. 1, the protective layer 50 is omitted for convenience.

The substrate 10 is made of, for example, alumina (Al)₂O₃) And the thickness of the ceramic is, for example, about 0.6mm to 1.0 mm. The substrate 10 has a rectangular plate shape extending long in the main scanning direction X. The substrate 10 has a main surface 11 and a back surface 12 facing opposite sides to each other in the plate thickness direction Z. A glass layer 20, an electrode layer 30, a resistor layer 40, and a protective layer 50 are formed on the main surface 11 of the substrate 10. A heat sink made of metal such as aluminum (Al) may be provided on the back surface 12 of the substrate 10.

The glass layer 20 is formed on the main surface 11 of the substrate 10, and is made of a glass material such as amorphous glass. The glass layer 20 has a glaze 21, a chip glaze 22, an intermediate glass layer 23, and a front glass layer 24.

The glaze 21 is a heat storage layer, and is formed in a band shape extending in the main scanning direction X in a plan view. The glaze 21 of the present embodiment is a so-called partial glaze, and is formed in such a manner that a cross-sectional shape cut by a plane including the sub-scanning direction Y and the plate thickness direction Z is formed in an arc shape protruding toward the opposite side of the substrate 10 in the plate thickness direction Z. The curvature of the arc-shaped glaze 21 can be set as appropriate according to the use of the thermal head 1. The dimension of the glaze 21 in the sub-scanning direction Y is, for example, about 700 μm. The dimension of the glaze 21 in the thickness direction Z is, for example, about 18 μm to 50 μm. That is, the dimension in the plate thickness direction Z from the main surface 11 of the substrate 10 to the top 21A of the glaze 21 is about 50 μm. The glaze 21 is provided to press the heat generating portion 41, which is a portion of the resistor layer 40 that generates heat, against the thermal recording paper to be printed.

The patch glaze 22 is formed in a band shape arranged in parallel with the glaze 21 at a position spaced apart from the glaze 21 on the upstream side in the sub-scanning direction Y. The patch glaze 22 supports a portion of the electrode layer 30 and the driver IC 61. The thickness of the patch glaze 22 is, for example, about 30 μm to 50 μm. The glass materials of the glaze 21 and the patch glaze 22 have a softening point of, for example, 800 to 850 ℃. Further, the patch glaze 22 may be omitted.

The intermediate glass layer 23 covers a region sandwiched by the glaze 21 and the die glaze 22 in the main surface 11 of the substrate 10 in the sub-scanning direction Y. The intermediate glass layer 23 is composed of a glass material having a lower softening point than the glass materials forming the glaze 21 and the patch glaze 22 when the softening point of the glass material is, for example, in the order of 680 ℃. The thickness of the intermediate glass layer 23 is, for example, about 2.0 μm. The front end glass layer 24 covers a part of a region on the downstream side in the sub-scanning direction Y with respect to the glaze 21. The front glass layer 24 is made of the same material and has the same thickness as the intermediate glass layer 23. The intermediate glass layer 23 and the front glass layer 24 are provided to eliminate irregularities on the main surface 11 of the substrate 10 and facilitate lamination of the electrode layer 30.

The electrode layer 30 constitutes a path for passing current to the resistor layer 40, and is formed on the glass layer 20. The electrode layer 30 is formed of, for example, gold (Au) resinate paste containing rhodium (Rh), vanadium (V), bismuth (Bi), silicon (Si), and the like as additive elements. The thickness of the electrode layer 30 is not particularly limited, and is, for example, about 0.6 μm to 1.2 μm. The electrode layer 30 has a common electrode 31 and a plurality of individual electrodes 32. The electrode layer 30 includes a glaze electrode layer 30A formed on the glaze 21.

As shown in fig. 2, the common electrode 31 includes a plurality of first strip portions 33, a connecting portion 34, and a bypass portion 35. The coupling portion 34 is formed in a belt shape extending in the main scanning direction X, and is connected to the plurality of first belt-shaped portions 33. The joint 34 is formed on a part of the glaze 21 and the front end glass layer 24. The downstream end of the coupling portion 34 in the sub-scanning direction Y is formed so as not to protrude beyond the front glass layer 24. Further, an upstream end of the coupling portion 34 in the sub-scanning direction Y is formed on a downstream end of the glaze 21. Each of the first strip portions 33 is formed in a strip shape extending from the connection portion 34 toward the glaze 21 in the sub-scanning direction Y. The leading edge of each first band portion 33 is located on the upstream side in the sub-scanning direction Y with respect to the glaze 21. In this way, the plurality of first strip portions 33 have portions constituted by the glaze electrode layer 30A. The plurality of first belt-shaped portions 33 are arranged at equal intervals in the main scanning direction X. The bypass portion 35 extends from one end portion of the connection portion 34 in the main scanning direction X to the upstream side in the sub scanning direction Y.

The individual electrode 32 locally supplies current to the resistor layer 40, and has a polarity opposite to that of the common electrode 31. The individual electrodes 32 are formed in a band shape extending from the glaze 21 to the patch glaze 22 in the sub-scanning direction Y. The individual electrode 32 has a second strip 36. The leading edge of each second strip portion 36 is located upstream of the top portion 21A of the glaze 21 in the sub-scanning direction Y and upstream of the connection portion 34 in the sub-scanning direction Y. In the present embodiment, the leading edge of each second band-shaped portion 36 is positioned closer to the connection portion 34 than the top portion 21A of the glaze 21 in the sub-scanning direction Y. Thus, the plurality of second strip portions 36 have portions constituted by the glaze electrode layer 30A. Each of the second strip portions 36 is disposed between the first strip portions 33 adjacent to each other in the main scanning direction X on the glaze 21. That is, the first belt-shaped portions 33 and the second belt-shaped portions 36 are arranged so as to overlap each other when viewed from the main scanning direction X, and are alternately arranged in the main scanning direction X. A welding portion 37 is provided at an upstream end portion of the individual electrode 32 in the sub-scanning direction Y. The welded portion 37 is formed to have a width dimension larger than that of the second band-shaped portion 36. Here, the width dimension of the second strip-shaped portion 36 is a dimension in a direction orthogonal to the direction in which the second strip-shaped portion 36 extends in plan view. The width dimension of the welded portion 37 is the maximum value of the dimension of the welded portion 37 in the main scanning direction X in plan view.

The driver IC61 has a function of selectively energizing the individual electrodes 32 to arbitrarily generate heat in any of a plurality of heat generating portions 41 of the resistor layer 40, which will be described later. As shown in fig. 1, in the present embodiment, the plurality of driver ICs 61 are arranged at intervals in the main scanning direction X. As shown in fig. 3, each of the driver ICs 61 is formed on the patch glaze 22. More specifically, a part of the electrode layer 30 (common electrode 32) is formed in a region where the driver IC61 is disposed on the die glaze 22. A support glass layer 25 is formed on a part of the electrode layer 30. The support glass layer 25 is made of, for example, amorphous glass. The driver IC61 is disposed on the support glass layer 25. As shown in fig. 2, a plurality of pads 62 are formed on each driver IC 61. The plurality of pads 62 are connected to the bonding portion 37 of the individual electrode 32 or a pad that is a part of the electrode layer 30 formed on the die-glaze pattern 22 via a plurality of wires 63. As shown in fig. 1, the plurality of driver ICs 61 are sealed by a sealing resin 64.

The resistor layer 40 is made of a material having a resistivity higher than that of the material constituting the electrode layer 30, for example, ruthenium oxide (Ru)O₂Or RuO₄) And the like, and is formed in a band shape extending in the main scanning direction X on the glaze 21 formed on the main surface 11 of the substrate 10. The resistor layer 40 is formed in an arc shape in a cross section obtained by cutting the head main body 1A with a plane along the sub-scanning direction Y and the plate thickness direction Z. The resistor layer 40 is formed by thick-film printing a paste of ruthenium oxide or the like and then firing the paste. The resistor layer 40 may be formed by a thin film forming technique such as sputtering. The thickness of the resistor layer 40 is not particularly limited, and is, for example, about 6 μm in the case of thick film printing, and about 0.05 μm to 0.2 μm in the case of thin film formation technology. In the present embodiment, the resistor layer 40 is formed by thick film printing.

The resistor layer 40 is formed on the glaze 21 so as to extend in the main scanning direction X. The resistor layer 40 is formed so as to intersect the glaze electrode layer 30A. In the present embodiment, the resistor layer 40 is formed so as to straddle the glaze electrode layer 30A. More specifically, the resistor layer 40 is formed on the plurality of first strip portions 33 and the plurality of second strip portions 36 so as to intersect with the plurality of first strip portions 33 and the plurality of second strip portions 36 constituting the glaze electrode layer 30A, respectively. That is, the resistor layer 40 is formed so as to extend over the plurality of first strip portions 33 and the plurality of second strip portions 36, respectively. As shown in fig. 4, the portions of the resistor layer 40 sandwiched between the first strip portions 33 and the second strip portions 36 in the main scanning direction X constitute heat generating portions 41. The heat generating portion 41 is a portion that generates heat by locally applying current to the resistor layer 40 with the electrode layer 30. By the heat generation of the heat generating portion 41, a print dot can be formed on the thermal recording paper.

The protective layer 50 is for protecting at least the resistor layer 40, and is made of, for example, amorphous glass. The protective layer 50 has a first protective layer 51 and a second protective layer 52.

As shown in fig. 3, the first protective layer 51 is formed in a region from just before the downstream-side end edge of the substrate 10 in the sub-scanning direction Y (for example, 0.1mm to 0.5mm upstream of the downstream-side end edge of the substrate 10 in the sub-scanning direction Y) to near the center of the die glaze 22. The first protective layer 51 covers at least the heat generating portion 41 of the resistor layer 40. In this embodiment, the first protective layer 51 covers the entire resistor layer 40 and most of the electrode layer 30. That is, the first protective layer 51 protects the resistor layer 40 and the electrode layer 30. The thickness of the first protective layer 51 is not particularly limited, and is, for example, about 6 μm to 8 μm.

The second protective layer 52 is formed on the first protective layer 51. The second protective layer 52 is formed in a region from the downstream-side end portion of the substrate 10 to the vicinity of the center of the intermediate glass layer 23 in the sub-scanning direction Y. In this way, the second protective layer 52 protects the electrode layer 30 and the resistor layer 40 on the glaze 21. The second protective layer 52 is a coating film containing silicon carbide (SiC) or titanium (Ti). The kind of the second protective layer 52 may also vary depending on the use of the thermal head 1 or the material of the thermal recording paper. The thickness of the second protective layer 52 is not particularly limited, and is preferably smaller than the thickness of the first protective layer 51. In this way, the thickness of the protective layer 50 (the total thickness of the first protective layer 51 and the thickness of the second protective layer 52) is greater than the thickness of the resistor layer 40.

With reference to fig. 4 and 5, the detailed shape and structure of the glaze 21 and its periphery will be explained. Fig. 5 shows a cross section of the glaze 21 and its periphery cut by a plane along the plate thickness direction Z and the main scanning direction X.

As shown in fig. 4, in the present embodiment, the resistor layer 40 is disposed on the top portion 21A of the glaze 21 having an arc-shaped cross-sectional shape obtained by cutting the head main body 1A with a plane extending in the sub-scanning direction Y and the plate thickness direction Z. The top 21A of the glaze 21 is a portion having the largest height Hg from the main surface 11 of the substrate 10 to the surface of the glaze 21 in the plate thickness direction Z, and is formed in the center of the glaze 21 in the sub-scanning direction Y in the present embodiment.

The cover glaze 21, the electrode layer 30, and the protective layer 50 covering the resistor layer 40 can be divided into a first portion 50A formed on the resistor layer 40, a second portion 50B on the downstream side of the first portion 50A in the sub-scanning direction Y, and a third portion 50C on the upstream side of the resistor layer 40 in the sub-scanning direction Y. In the present embodiment, the thickness of the second portion 50B is thicker than the thickness of the first portion 50A. The thickness of the third portion 50C is greater than the thickness of the first portion 50A and equal to the thickness of the second portion 50B. Here, the thickness of the first portion 50A represents a dimension of the first portion 50A in a direction perpendicular to the surface of the glaze 21. The thickness of the second portion 50B is the thickness of the portion of the second portion 50B where the first protective layer 51 and the second protective layer 52 are laminated, and the portion on the downstream side of the glaze 21 in the sub-scanning direction Y represents the dimension of the second portion 50B in the plate thickness direction Z, and the portion formed on the glaze 21 represents the dimension of the second portion 50B in the direction perpendicular to the surface of the glaze 21. The thickness of the third portion 50C is the thickness of the portion of the third portion 50C where the first protective layer 51 and the second protective layer 52 are laminated, and the portion on the upstream side in the sub-scanning direction Y from the glaze 21 shows the dimension of the third portion 50C in the plate thickness direction Z, and the portion formed on the glaze 21 shows the dimension of the third portion 50C in the vertical direction from the surface of the glaze 21.

In the present embodiment, the first portion 50A is formed so that the thickness of the portion covering the top portion 40A of the resistor layer 40 is the smallest, and the thickness increases toward the downstream side of the first portion 50A in the sub-scanning direction Y. More specifically, the thickness of the first protective layer 51 in the first portion 50A is thinnest at the top portion 40A of the resistor layer 40, and becomes thicker toward the downstream side of the first portion 50A in the sub-scanning direction Y. In addition, the thickness of the second protective layer 52 is constant from the portion covering the top portion 40A of the resistor layer 40 to the end portion on the downstream side in the sub-scanning direction Y. Therefore, the thickness of the first portion 50A, which is the sum of the thickness of the first protective layer 51 and the thickness of the second protective layer 52 in the first portion 50A, becomes thicker toward the downstream side in the sub-scanning direction Y from the portion covering the top portion 40A of the resistor layer 40.

In the present embodiment, the first portion 50A is formed to have a larger thickness as going from the portion covering the top portion 40A of the resistor layer 40 to the upstream side in the sub-scanning direction Y. In more detail, the thickness of the first protective layer 51 in the first portion 50A becomes thicker going to the upstream side in the sub-scanning direction Y from the portion covering the top 40A of the resistor layer 40. In addition, the thickness of the second protective layer 52 is constant from the portion covering the top portion 40A of the resistor layer 40 to the end portion on the upstream side in the sub-scanning direction Y. Therefore, the thickness of the first portion 50A, which is the sum of the thickness of the first protective layer 51 and the thickness of the second protective layer 52 in the first portion 50A, becomes thicker toward the upstream side in the sub-scanning direction Y from the portion covering the top portion 40A of the resistor layer 40.

According to such a structure of the protective layer 50, AS shown in fig. 4, the second portion 50B has a second face 50BS, the second face 50BS being equal to a height (first height) Hp1 from the main face 11 of the substrate 10 to the first face 50AS of the outermost surface of the first portion 50A. In the present embodiment, the second surface 50BS is constituted by the outermost surface of the portion of the surface 50BT of the second portion 50B adjacent to the first portion 50A in the sub-scanning direction Y. Further, as for the height Hp1, an error is included in which the absolute value of the difference between the height Hp2 and the height Hp1 from the main surface 11 of the substrate 10 to the second surface 50BS of the second portion 50B is within 5% of the height Hp 1. That is, the case where the height Hp1 is greater than the height Hp2 by an error amount is included. The height Hp1 and the height Hp2 each indicate a height dimension in a direction (plate thickness direction Z) perpendicular to the main surface 11 of the substrate 10. The height Hp1 is a height dimension from the main surface 11 of the substrate 10 to the top 40A of the resistor layer 40. However, the resistor layer 40 is formed such that the heat generating portions 41 are recessed from portions of the resistor layer 40 formed on the first strip portions 33 or the second strip portions 36 of the electrode layer 30 (hereinafter, referred to as "current carrying portions 42"). That is, the height of the heat generating portion 41 from the main surface 11 of the substrate 10 to the top 40A of the resistor layer 40 is smaller than the height of the conducting portion 42 from the main surface 11 of the substrate 10 to the top 40A of the resistor layer 40. Therefore, in the present embodiment, the height Hp1 is defined as the height dimension from the main surface 11 of the substrate 10 to the top 40A of the resistor layer 40 of the portion of the resistor layer 40 formed on the first strip portion 33 or the second strip portion 36 of the electrode layer 30. The height Hp2 of the portion of the surface 50BT of the second portion 50B on the downstream side in the sub-scanning direction Y from the main surface 11 of the substrate 10 with respect to the second surface 50BS is smaller. In the present embodiment, the height Hp1 corresponds to the first height.

In the present embodiment, the height Hp1 is equal to the height from the main surface 11 of the substrate 10 to the first surface 50AS of the first portion 50A, at a portion downstream in the sub-scanning direction Y of the top portion 40A of the resistor layer 40. That is, in the cross section of the head main body 1A cut along the plane in the sub-scanning direction Y and the plate thickness direction Z, the protective layer 50 is formed to have a flat shape from the top portion 40A of the resistor layer 40 in the first portion 50A to a portion adjacent to the first portion 50A in the sub-scanning direction Y in the second portion 50B.

As shown in fig. 5, the protective layer 50 is formed such that the height Hp1 of the first portion 50A is equal in the main scanning direction X as viewed from the sub scanning direction Y. Specifically, the position of the resistor layer 40 in the thickness direction Z is different from that of the heat generating portion 41 in the conducting portion 42, the conducting portion 42 is a portion extending across the first strip-shaped portion 33 of the common electrode 31 and the second strip-shaped portion 36 of the individual electrode 32, and the heat generating portion 41 is a portion located between the first strip-shaped portion 33 and the second strip-shaped portion 36 in the main scanning direction X. The position of the current-carrying portion 42 in the plate thickness direction Z is located above the position of the heat generating portion 41 in the plate thickness direction Z. The thickness of the first portion 50A corresponding to the conducting portion 42 of the resistor layer 40 is thinner than the thickness of the first portion 50A corresponding to the heat generating portion 41 of the resistor layer 40. In addition, the thickness of the second protective layer 52 in the first portion 50A is constant. Therefore, the height Hp1 of the first portion 50A of the protective layer 50 is equal in the main scanning direction X. In the present embodiment, the height Hx of the first protective layer 51 formed as the first portion 50A from the main surface 11 of the substrate 10 is equal in the main scanning direction X.

Next, a method of manufacturing the thermal head 1 will be described with reference to fig. 6 and fig. 7A to 7G.

As shown in fig. 6, the method of manufacturing the thermal head 1 includes a glass layer forming process (step S10), an electrode layer forming process (step S20), a resistor layer forming process (step S30), a protective layer forming process (step S40), a drive IC mounting process (step S50), a drive IC sealing process (step S60), and a connector mounting process (step S70).

As shown in fig. 7A, in the glass layer forming step, a glass layer 20 is formed on the main surface 11 of the substrate 10. Specifically, first, the glaze 21 and the die glaze 22 are formed on the main surface 11 of the substrate 10. The glaze 21 and the patch glaze 22 are formed by thick-film printing an amorphous glass paste on the main surface 11 of the substrate 10, and then firing the thick-film printed paste at 800 to 850 ℃. Next, the intermediate glass layer 23 and the front glass layer 24 are formed on the main surface 11 of the substrate 10. The intermediate glass layer 23 and the front glass layer 24 are each formed by thick-film printing of paste containing amorphous glass on the main surface 11 of the substrate 10, and then firing the thick-film printed paste at, for example, 790 to 800 ℃. In this way, the glass layer forming step includes a glaze forming step of forming the glaze 21 on the main surface 11 of the substrate 10.

As shown in fig. 7B, in the electrode layer forming step, the electrode layer 30 is formed on the glass layer 20 formed in the glass layer forming step. The electrode layer 30 is formed by, for example, thick-film printing a gold (Au) resinate paste to which rhodium (Rh), vanadium (V), bismuth (Bi), silicon (Si), or the like is added as an additive element on the glass layer 20, and then firing the thick-film printed paste. In the electrode layer forming step, since the plurality of first strip portions 33 and the plurality of second strip portions 36 are formed on the glaze 21, the electrode layer forming step includes a glaze electrode layer forming step of forming the glaze electrode layer 30A on the glaze 21. The electrode layer 30 may be formed by a thin film forming technique such as sputtering, or may be formed by stacking a plurality of Au layers.

As shown in fig. 7C, in the resistor layer forming step, the resistor layer 40 is formed on the glaze 21. The resistor layer 40 is formed by thick-film printing a paste containing ruthenium oxide so as to straddle the plurality of first strip portions 33 of the common electrode 31 of the electrode layer 30 and the plurality of second strip portions 36 of the individual electrodes 32 (both see fig. 2), and then firing the thick-film printed paste.

The protective layer forming step includes a first step and a second step. As shown in fig. 7D, in the first step, a protective layer 50 covering the resistor layer 40 and a part of the electrode layer 30 is formed on the glass layer 20. A portion of the electrode layer 30 includes a glaze electrode layer 30A. Specifically, the first protective layer 51 is formed first. The first protective layer 51 is formed by thick-film printing a paste containing amorphous glass on the glass layer 20 so as to cover the resistor layer 40 and a part of the electrode layer 30, and then firing the thick-film printed paste. Next, the surface of the portion (first portion 50A) of the first protective layer 51 covering the resistor layer 40 is polished. More specifically, the surface of the first protective layer 51 covering the top portion 40A of the resistor layer 40 and the surface of the portion downstream of the top portion 40A in the sub-scanning direction Y are polished. As the polishing of the surface of the first protective layer 51, for example, Chemical Mechanical Polishing (CMP) is used. The height Hy is equal to the height Hx, where the height Hy is a height of a portion of the second portion 50B of the first protection layer 51 adjacent to the first portion 50A from the main surface 11 of the substrate 10, and the height Hx is a height of a portion of the first portion 50A of the first protection layer 51 covering the top 40A of the resistor layer 40 from the main surface 11 of the substrate 10. Instead of polishing, the surface of the first protective layer 51 covering the top portion 40A of the resistor layer 40 and the portion downstream of the top portion 40A in the sub-scanning direction Y may be cut.

As shown in fig. 7E, in the second step, a second protective layer 52 is formed. Specifically, the film is formed by performing a sputtering method or a CVD method using silicon carbide (SiC) or titanium (Ti). The first protective layer 51 may be formed by, for example, performing a sputtering method or a CVD method using amorphous glass after forming a mask for exposing a desired region.

As shown in fig. 7E, in the second step, the surface of the portion (first portion 50A) of the protective layer 50 corresponding to the resistor layer 40 is polished. More specifically, the surface of the protective layer 50 is polished at a portion corresponding to the top portion 40A of the resistor layer 40 and at a portion downstream of the top portion 40A in the sub-scanning direction Y. Thus, the portion of the second portion 50B adjacent to the first portion 50A has a second face 50BS equal to the height Hp1 from the major face 11 of the substrate 10 to the first face 50AS of the first portion 50A. Instead of polishing, the surface of the protective layer 50 may be cut at a portion corresponding to the top portion 40A of the resistor layer 40 and at a portion downstream of the top portion 40A in the sub-scanning direction Y.

As shown in fig. 7F, in the driver IC mounting step, first, the support glass layer 25 is formed on a part of the electrode layer 30 formed on the die glaze 22. The support glass layer 25 is formed by thick-film printing a paste of, for example, amorphous glass on a part of the electrode layer 30 formed on the patch glaze 22 and firing the thick-film printed paste. Next, the driver IC61 is mounted on the support glass layer 25. The support glass layer 25 and the driver IC61 are bonded by a bonding material such as solder. Next, the pad 62 (see fig. 2) of the driver IC61 and the pad formed on the bonding portion 37 (see fig. 2) of the individual electrode 32 and a part of the electrode layer 30 on the die glaze 22 are connected by, for example, wire bonding.

As shown in fig. 7G, in the drive IC sealing step, the lead wires 63 and the drive ICs 61 formed by pressure welding are covered with a sealing resin 64. The sealing resin 64 is made of, for example, a black insulating resin.

In the connector mounting step, the connector 1B is mounted on the center of the main surface 11 of the substrate 10 in the main scanning direction X and on the upstream side end in the sub-scanning direction Y. Through the above steps, the thermal head 1 is manufactured.

The operation of the present embodiment will be described with reference to fig. 8 to 11.

Fig. 8 shows a schematic configuration of a part of the thermal head of the comparative example, and fig. 9 shows the result of the retention degree of printing waste in the case of printing on thermal recording paper using the thermal head of the comparative example.

As shown in fig. 8, the thermal head 100 of the comparative example is formed by laminating a glaze 120, an electrode layer 130, a resistor layer 140, and a protective layer 150 in this order on the main surface 111 of a substrate 110. A protrusion 151 is formed on a portion of the protective layer 150 covering the resistor layer 140. In a cross section obtained by cutting the head main body 101 of the thermal head 100 on a plane in the plate thickness direction Z and the sub-scanning direction Y, the shapes of the glaze 120, the electrode layer 130, and the resistor layer 140 are the same as those of the glaze 21, the electrode layer 30, and the resistor layer 40 in the present embodiment.

When the thermal recording paper P is conveyed by a rubber roller (gum roller)200 of the thermal printer and is printed on the projections 151 corresponding to the resistor layers 140, the thermal recording paper P is conveyed in a state separated from the surface on the downstream side in the sub-scanning direction Y of the projections 151. Therefore, the printing waste Cx generated along with the printing of the thermal recording paper P is accumulated in the gap between the protrusion 151 and the thermal recording paper P. As a result, as shown in fig. 9, in the thermal head 100 of the comparative example, a large amount of printing waste Cx remains on the downstream side in the sub-scanning direction Y with respect to the resistor layer 140.

On the other hand, AS shown in fig. 10, in the thermal head 1 of the present embodiment, the second surface 50BS of the second portion 50B of the protective layer 50 adjacent to the first portion 50A is equal to the height Hp1 from the main surface 11 of the substrate 10 to the first surface 50AS of the first portion 50A. The first surface 50AS and the second surface 50BS are surfaces of the protective layer 50 that face the rubber roller 200 and the thermal recording paper P. Thus, AS shown in fig. 9, when the thermal recording paper P is conveyed by the rubber roller 200 and printed in the first portion 50A, the thermal recording paper P contacts the portion of the first surface 50AS of the first portion 50A on the downstream side in the sub-scanning direction Y with respect to the top 40A of the resistor layer 40 and the second surface 50BS of the portion of the second portion 50B adjacent to the first portion 50A. That is, it is difficult to generate a gap between the thermal recording paper P and the protective layer 50 at a portion of the protective layer 50 immediately after printing. Thereby, the thermal recording paper P after printing sweeps the printing waste at the downstream side in the sub-scanning direction Y of the first portion 50A of the protective layer 50 and at the downstream side in the sub-scanning direction Y of the first portion 50A. As a result, as shown in fig. 11, in the thermal head 1 of the present embodiment, the printing waste Cx hardly remains on the downstream side in the sub-scanning direction Y with respect to the resistor layer 40.

According to the thermal head 1 of the present embodiment, the following effects can be obtained.

(1-1) the protective layer 50 has: a first portion 50A formed on the resistor layer 40; and a second portion 50B disposed downstream of the first portion 50A in the sub-scanning direction Y. The second portion 50B has a second face 50BS equal to a height Hp1, where the height Hp1 is the height of the first face 50AS of the first portion 50A from the major face 11 of the substrate 10. According to this configuration, when the thermal recording paper P is conveyed, the thermal recording paper P is in contact between the first surface 50AS of the first portion 50A and the second surface 50BS of the second portion 50B in the sub-scanning direction Y, whereby the printing waste Cx generated when the thermal recording paper P is printed in the first portion 50A can be swept out. Therefore, the printing waste Cx is hard to be retained between the first face 50AS of the first section 50A and the second face 50BS of the second section 50B in the sub-scanning direction Y.

(1-2) the thickness of the second portion 50B of the protective layer 50 is thicker than the thickness of the first portion 50A. With this structure, the height Hp2 of the second surface 50BS of the second portion 50B from the main surface 11 can be made equal to the height Hp1 of the first surface 50AS of the first portion 50A from the main surface 11 of the substrate 10 without changing the shape of the glaze 21 or the position of the resistor layer 40 with respect to the glaze 21.

(1-3) the protective layer 50 has: a first protective layer 51 covering the resistor layer 40 and the electrode layer 30; and a second protective layer 52 covering the first protective layer 51. The second protective layer 52 is provided at a portion corresponding to the glaze 21. With this configuration, the electrode layer 30 and the resistor layer 40 on the glaze 21 can be protected more reliably.

(1-4) the resist forming step in the method of manufacturing the thermal head 1 is to polish the first portion 50A of the resist 50 so that the height Hp2 of the second surface 50BS of the second portion 50B from the main surface 11 of the substrate 10 is equal to the height Hp1 of the first surface 50AS of the first portion 50A from the main surface 11 of the substrate 10. With this structure, since the height Hp2 can be adjusted by polishing of the protective layer 50, the height Hp2 and the height Hp1 can be easily made equal to each other.

(second embodiment)

A thermal head 1 according to a second embodiment will be described with reference to fig. 12A to 15. The resistor layer 40 of the thermal head 1 of the present embodiment is different in position from the glaze 21 in the sub-scanning direction Y compared to the thermal head 1 of the first embodiment. In the following description, the same components as those of the thermal head 1 according to the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

As shown in fig. 12A, the resistor layer 40 is disposed on the upstream side of the top portion 21A of the glaze 21 in the sub-scanning direction Y. Specifically, the resistor layer 40 is disposed on the upstream side in the sub-scanning direction Y with respect to the top portion 21A of the glaze 21 so that the height Hr from the main surface 11 of the substrate 10 to the resistor layer 40 (current carrying portion 42) in the plate thickness direction Z is equal to the height Hg from the main surface 11 of the substrate 10 to the portion of the electrode layer 30 covering the top portion 21A of the glaze 21 in the plate thickness direction Z. Although not shown, the resistor layer 40 is disposed upstream of the top 21A of the glaze 21 in the sub-scanning direction Y so that the height from the main surface 11 of the substrate 10 to the resistor layer 40 (heat generating portion 41) in the plate thickness direction Z is equal to the height from the main surface 11 of the substrate 10 to the top 21A of the glaze 21 in the plate thickness direction Z. In the present embodiment, the protective layer 50 is formed so that the connection line LX, which connects the portion of the first surface 50AS of the first portion 50A of the protective layer 50 formed on the resistor layer 40 where the height Hp1 from the main surface 11 of the substrate 10 is the largest, and the portion of the surface 50BT of the second portion 50B of the protective layer 50 formed on the top portion 21A of the glaze 21, is parallel to the main surface 11 of the substrate 10. In other words, the height Hp1 is equal to the height Hp3, where the height Hp3 is the height of the portion of the surface 50BT of the second portion 50B formed on the top 21A of the glaze 21 from the major surface 11 of the substrate 10. Here, the height Hp1 is equal to the height Hp3, and includes an error in which the absolute value of the difference between the height Hp1 and the height Hp3 is within 5% of the height Hp 3.

Thus, the second portion 50B has a second face 50BS that is equal to the height Hp 1. In the present embodiment, the second face 50BS is the outermost surface of the portion of the second portion 50B formed on the top 21A of the glaze 21. Therefore, the height of the second surface 50BS from the main surface 11 of the substrate 10 is the height Hp 3.

As shown in fig. 13, when viewed from the plate thickness direction Z, the distance DY1 between the front edge of the first strip portion 33 of the common electrode 31 of the electrode layer 30 and the resistor layer 40 in the sub-scanning direction Y is smaller than the distance DY2 between the front edge of the second strip portion 36 of the individual electrode 32 and the resistor layer 40 in the sub-scanning direction Y.

As shown in fig. 12B, the resistor layer 40 is formed such that the top 40A thereof is biased to the upstream side in the sub-scanning direction Y with respect to the center of the resistor layer 40. The center of the resistor layer 40 is a position where, in a cross section obtained by cutting the head main body 1A on a plane in the plate thickness direction Z and the sub-scanning direction Y, for example, the center of the resistor layer 40 in a direction along the surface 30S of the portion of the electrode layer 30 where the resistor layer 40 is formed, and a center line CL perpendicular to the surface 30S of the electrode layer 30 is formed. As shown in fig. 12B, the top 40A of the resistor layer 40 is located upstream in the sub-scanning direction Y from the center line CL. Therefore, the length in the sub-scanning direction Y of the portion from the top 40A of the resistor layer 40 to the downstream end 40B in the sub-scanning direction Y is longer than the length in the sub-scanning direction Y of the portion from the upstream end 40C in the sub-scanning direction Y of the resistor layer 40 to the top 40A. The glaze 21 is curved in a convex shape in the direction away from the main surface 11 of the substrate 10 in the plate thickness direction Z as it goes from a position corresponding to an upstream end edge 40C of the resistor layer 40 in the sub-scanning direction Y to a position corresponding to a downstream end edge 40B of the resistor layer 40 in the sub-scanning direction Y (see fig. 12A). Therefore, the distance in the plate thickness direction Z from the top portion 40A to the end portion 40B of the resistor layer 40 is smaller than the distance in the plate thickness direction Z from the end portion 40C to the top portion 40A of the resistor layer 40. The distance in the plate thickness direction Z from the top 40A to the end 40B of the resistor layer 40 is smaller than the distance in the sub-scanning direction Y from the top 40A to the end 40B of the resistor layer 40. In the present embodiment, the distance in the plate thickness direction Z from the end edge 40B of the resistor layer 40 (current carrying portion 42) to the portion of the electrode layer 30 covering the top portion 21A of the glaze 21 is smaller than the distance in the sub-scanning direction Y from the end edge 40B of the resistor layer 40 (current carrying portion 42) to the portion of the electrode layer 30 covering the top portion 21A of the glaze 21. The distance in the plate thickness direction Z from the end edge 40B of the resistor layer 40 (heat generating portion 41) to the top portion 21A of the glaze 21 is smaller than the distance in the sub-scanning direction Y from the end edge 40B of the resistor layer 40 (heat generating portion 41) to the top portion 21A of the glaze 21.

As shown in fig. 12A, a concave portion 52A is formed between a portion of the first portion 50A of the protective layer 50 on the downstream side in the sub-scanning direction Y with respect to the top portion 40A of the resistor layer 40 and the top portion 21A of the glaze 21 in the sub-scanning direction Y. As described above, since the depth of the recess formed by the glaze 21 (electrode layer 30) and the portion of the resistor layer 40 on the downstream side in the sub-scanning direction Y from the top portion 40A is smaller than the depth of the recess formed by the glaze 21 (electrode layer 30) and the portion on the upstream side in the sub-scanning direction Y from the top portion 40A, the depth of the recess 52A is smaller than the projecting distance from the bottom of the recess 52B formed between the third portion 50C and the first portion 50A to the top of the first portion 50A (the portion where the connection line LX is connected to the first portion 50A). The projecting distance is a distance between the bottom of the recess 52B and the top of the first portion 50A (the portion where the line LX meets the first portion 50A) in the thickness direction of the layer of the second protective layer 52.

The distance in the plate thickness direction Z from the bottom of the recess 52A to the portion of the first portion 50A covering the top 40A of the resistor layer 40 is smaller than the distance in the sub-scanning direction Y from the bottom of the recess 52A to the portion of the first portion 50A covering the top 40A of the resistor layer 40. The distance in the plate thickness direction Z from the bottom of the recess 52A to the top 21A of the second portion 50B covering the glaze 21 is smaller than the distance in the sub-scanning direction Y from the bottom of the recess 52A to the top 21A of the second portion 50B covering the glaze 21. Therefore, the concave portion 52A gradually inclines.

The operation of the present embodiment will be described with reference to fig. 14 and 15.

As shown in fig. 14, the recess 52A of the protective layer 50 is gently inclined and has a height Hp1 equal to a height Hp3, where Hp1 is the height of the first portion 50A of the protective layer 50 covering the resistor layer 40 from the main surface 11 of the substrate 10, and Hp3 is the height of the portion of the second portion 50B covering the top 21A of the glaze 21 from the main surface 11 of the substrate 10.

Thereby, as shown in fig. 14, in the case where the thermal recording paper P is conveyed by the rubber roller 200 and printed in the first portion 50A, the thermal recording paper P contacts the portions of the first portion 50A and the second portion 50B of the protective layer 50 that cover the tops 21A of the glazes 21, and therefore, the thermal recording paper P easily contacts the recessed portions 52A. That is, the thermal recording paper P easily contacts the portion of the protective layer 50 from the portion of the first portion 50A covering the top 40A of the resistor layer 40 to the portion of the second portion 50B covering the top 21A of the glaze 21 during conveyance. Therefore, in the portion of the protective layer 50 immediately after printing, a gap is less likely to be generated between the thermal recording paper P and the protective layer 50. Thereby, the thermal recording paper P after printing sweeps the printing waste at the downstream side in the sub-scanning direction Y of the first portion 50A of the protective layer 50 and at the downstream side in the sub-scanning direction Y of the first portion 50A. As a result, as shown in fig. 15, in the thermal head 1 according to the present embodiment, the printing waste Cx hardly remains on the downstream side in the sub-scanning direction Y with respect to the resistor layer 40.

According to the thermal head 1 of the present embodiment, the following effects can be obtained in addition to the effects (1-1) and (1-3) of the first embodiment.

(2-1) the resistor layer 40 is disposed on the upstream side of the top portion 21A of the glaze 21 in the sub-scanning direction Y. With this structure, the difference between the height Hr of the top portion 40A of the resistor layer 40 from the main surface 11 of the substrate 10 and the height Hg of the top portion 21A of the glaze 21 from the main surface 11 of the substrate 10 is smaller than in the structure in which the resistor layer 40 is located on the top portion 21A of the glaze 21. Therefore, the depth of the recess 52A formed between the first face 50AS of the first part 50A and the second face 50BS of the second part 50B of the protective layer 50 becomes shallow. Therefore, when the thermal recording paper P is conveyed, the thermal recording paper P easily comes into contact with the recessed portion 52A, and the printing waste Cx generated when the thermal recording paper P is printed on the first surface 50AS of the first portion 50A is easily swept out. Therefore, the printing waste Cx is difficult to stagnate between the first portion 50A and the portion of the second portion 50B adjacent to the first portion 50A in the sub-scanning direction Y.

Further, when the thermal recording paper P is conveyed, the thermal recording paper P comes into contact with the second surface 50BS of the second portion 50B, and therefore the printing waste Cx of the second portion 50B is swept out on the downstream side in the sub-scanning direction Y. Therefore, the printing waste Cx is less likely to stagnate at the downstream side in the sub-scanning direction Y than the first surface 50AS of the first portion 50A.

(2-2) the top 40A of the resistor layer 40 is formed so as to be biased to the upstream side in the sub-scanning direction Y. With this structure, the thermal recording paper P easily contacts the portion of the protective layer 50 corresponding to the top 40A of the resistor layer 40. Therefore, the printing accuracy on the thermal recording paper P becomes high. In addition, compared to the configuration in which the top portion 40A of the resistor layer 40 is formed at the center of the resistor layer 40 in the sub-scanning direction Y, the distance between the top portion 40A of the resistor layer 40 and the edge 40C of the resistor layer 40 in the sub-scanning direction Y is increased, and the distance between the top portion 40A of the resistor layer 40 and the edge 40C of the resistor layer 40 in the plate thickness direction Z is decreased. Therefore, the depth of the recess 52A formed between the first portion 50A of the protective layer 50 and the portion of the second portion 50B adjacent to the first portion 50A on the downstream side in the sub-scanning direction Y becomes shallow. Therefore, when the thermal recording paper P is conveyed, the thermal recording paper P easily comes into contact between the first portion 50A and a portion of the second portion 50B adjacent to the first portion 50A in the sub-scanning direction Y, and the printing waste Cx generated when the thermal recording paper P is printed in the first portion 50A is easily swept out. Therefore, the printing waste Cx is difficult to stagnate between the first portion 50A and the portion of the second portion 50B adjacent to the first portion 50A in the sub-scanning direction Y.

(2-3) in the method of manufacturing the thermal head 1, the resistor layer forming step forms the resistor layer 40 on the upstream side in the sub-scanning direction Y with respect to the top portion 21A of the glaze 21. According to this structure, a step of adjusting the height of the second portion 50B from the principal surface 11 of the substrate 10 to be equal to the height Hp1 from the principal surface 11 of the substrate 10 to the first surface 50AS of the first portion 50A is not required, and therefore an increase in the manufacturing cost of the thermal head 1 can be suppressed.

(modification example)

The above embodiments are illustrative of the form that can be adopted by the thermal head and the method of manufacturing the thermal head according to the present invention, and are not intended to be limiting. The thermal head and the method of manufacturing the thermal head according to the present invention can adopt a different form from the form exemplified in the above embodiments. Examples thereof include a mode in which a part of the configuration of each of the above embodiments is replaced, changed, or omitted, or a mode in which a new configuration is added to each of the above embodiments. In the following modifications, the same portions as those of the above embodiments are denoted by the same reference numerals as those of the above embodiments, and descriptions thereof are omitted.

In the first embodiment, the structure of the second surface 50BS of the second portion 50B, which is equal in height to the height Hp1 from the main surface 11 of the substrate 10 to the first surface 50AS of the first portion 50A of the protective layer 50, can be arbitrarily changed. In one example, as shown in fig. 16, a third protective layer (another protective layer) 53 is formed on the first protective layer 51 corresponding to the second face 50BS of the second portion 50B of the protective layer 50. The third protective layer 53 is formed of, for example, the same material as the first protective layer 51. The third protective layer 53 is formed by, for example, baking amorphous glass at a temperature lower than the softening point of the amorphous glass of the first protective layer 51. The third protective layer 53 is formed so as to cover a portion of the first portion 50A of the protective layer 50 on the downstream side in the sub-scanning direction Y from the portion formed on the top portion 40A of the resistor layer 40. As shown in fig. 16, the third protective layer 53 is formed such that, for example, the height Hp2 of the second face 50BS from the main face 11 of the substrate 10 is equal to the height Hp1, wherein the second face 50BS is the surface of the portion of the second portion 50B of the protective layer 50 adjacent to the downstream side of the first portion 50A in the sub-scanning direction Y.

With this configuration, the thermal recording paper P conveyed by the rubber roller 200 (see fig. 8) contacts the portion of the first portion 50A on the downstream side in the sub-scanning direction Y from the portion formed on the top portion 40A of the resistor layer 40 and the portion of the third protective layer 53 adjacent to the first portion 50A in the sub-scanning direction Y. Therefore, the printing waste generated when the thermal recording paper P is printed by the first portion 50A is swept out along with the conveyance of the thermal recording paper P. Therefore, the printing waste is less likely to remain in the portion of the first portion 50A on the downstream side in the sub-scanning direction Y than the portion corresponding to the top portion 40A of the resistor layer 40 and the portion of the third protective layer 53 adjacent to the first portion 50A in the sub-scanning direction Y.

In the modification shown in fig. 16, the third protective layer 53 is not limited to be formed between the first protective layer 51 and the second protective layer 52, and may be formed on the second protective layer 52. In this case, a portion of the surface of the third protective layer 53 having a height equal to the height Hp1 from the main surface 11 of the substrate 10 is configured as the second surface 50 BS. The third protective layer 53 is formed of, for example, the same material as the second protective layer 52.

In addition, the third protective layer 53 may be formed between the first protective layer 51 and the glaze 21. In this case, the third protective layer 53 covers the first strip portions 33 of the common electrode 31, the distal ends of the second strip portions 36 of the individual electrodes 32, and the portion of the resistor layer 40 on the downstream side in the sub-scanning direction Y from the top portion 40A.

In the first embodiment, the resistor layer 40 may be disposed on the upstream side of the top portion 21A of the glaze 21 in the sub-scanning direction Y. In this case, AS shown in fig. 17, the protective layer 50 is polished so that a height Hp1 is equal to a height Hp2, where Hp1 is a height from the main surface 11 of the substrate 10 of a portion of the first surface 50AS of the first portion 50A of the protective layer 50 formed on the top portion 40A of the resistor layer 40, and Hp2 is a height from the main surface 11 of the substrate 10 of a second surface 50BS that is a surface of a portion of the second portion 50B adjacent to the first portion 50A on the downstream side in the sub-scanning direction Y. In fig. 17, a portion of the second portion 50B adjacent to the first portion 50A on the downstream side in the sub-scanning direction Y is a portion of the second portion 50B formed on the top 21A of the glaze 21. Thus, the height Hp1 is equal to the height Hp3, where the height Hp2 is the height of the portion of the surface 50BT of the second portion 50B formed on the top 21A of the glaze 21 (the second face 50BS) from the major face 11 of the substrate 10. Therefore, in the first portion 50A, the thickness of the portion of the first portion 50A on the downstream side in the sub-scanning direction Y from the top portion 40A of the resistor layer 40 is thicker than the thickness of the portion of the first portion 50A corresponding to the top portion 40A of the resistor layer 40. In addition, the thickness of the first portion 50A becomes thicker as going to the downstream side in the sub scanning direction Y of the first portion 50A. The first portion 50A has a portion where the thickness of the portion of the first portion 50A on the upstream side in the sub-scanning direction Y from the top portion 40A of the resistor layer 40 is thicker than the thickness of the portion of the first portion 50A corresponding to the top portion 40A of the resistor layer 40. With this configuration, the effect (1-1) of the first embodiment can be obtained.

As shown in fig. 18, in the case where the resistor layer 40 is disposed on the upstream side of the top portion 21A of the glaze 21 in the sub-scanning direction Y, the third protective layer 53 may be formed on the second portion 50B of the first protective layer 51. The third protective layer 53 is formed, for example, to have a height Hp2 equal to a height Hp1, where Hp2 is the height from the main surface 11 of the substrate 10 of the second face 50BS, which is the surface of the portion of the second portion 50B of the protective layer 50 adjacent to the downstream side of the first portion 50A in the sub-scanning direction Y, and the height Hp1 is the height from the main surface 11 of the substrate 10 of the first face 50AS of the first portion 50A. In fig. 18, a portion of the second portion 50B adjacent to the first portion 50A on the downstream side in the sub-scanning direction Y is a portion of the second portion 50B formed on the top 21A of the glaze 21. Thus, the height Hp1 is equal to the height Hp3, where the height Hp3 is the height of the portion of the surface 50BT of the second portion 50B formed on the top 21A of the glaze 21 (the second face 50BS) from the major face 11 of the substrate 10. With this configuration, the effect (1-1) of the first embodiment can be obtained.

In the second embodiment, the position of the resistor layer 40 with respect to the top portion 21A of the glaze 21 can be arbitrarily changed within the range on the upstream side in the sub-scanning direction Y with respect to the top portion 21A of the glaze 21. In one example, AS shown in fig. 19, the resistor layer 40 is disposed such that the height Hp3 is higher than the height Hp1, where Hp3 is the height from the main surface 11 of the substrate 10 to the portion of the surface 50BT of the second portion 50B formed on the top 21A of the glaze 21, and Hp1 is the height from the main surface 11 of the substrate 10 to the first surface 50AS of the first portion 50A. With this configuration, the effect (2-1) of the second embodiment can be obtained.

In each of the above embodiments, the resistor layer 40 is formed on the electrode layer 30, but the present invention is not limited thereto. For example, the resistor layer 40 may be formed on the glaze 21, and the first strip portions 33 and the second strip portions 36 of the electrode layer 30 may be formed so as to straddle over the resistor layer 40.

In each of the above embodiments, the partial glaze is formed as the glaze 21, but the type of the glaze 21 is not limited thereto. The glaze 21 may also be formed as any one of, for example, a thin glaze, a double-layer glaze, a fine glaze, and an ultra-fine glaze.

In the method of manufacturing the thermal head 1 according to the first embodiment, the first portion 50A of the first protective layer 51 of the protective layer 50 is polished, but the method is not limited thereto.

In the first example, the first portion 50A of the second protective layer 52 may be polished. In this case, in the first step of the protective layer forming step, the first protective layer 51 is formed. In this case, the first protective layer 51 is not polished. Next, in the second step of the protective layer forming step, as shown in fig. 20, after the second protective layer 52 covering the resistor layer 40 and a part of the electrode layer 30 is formed, the first part 50A of the second protective layer 52 is polished. In this case, the second protective layer 52 is polished so that the height Hp2 is equal to or greater than the height Hp1, where the height Hp2 is the height from the main surface 11 of the substrate 10 of the portion of the second portion 50B of the second protective layer 52 adjacent to the first portion 50A in the sub-scanning direction Y, and the height Hp1 is the height from the main surface 11 of the substrate 10 of the first portion 50A of the second protective layer 52. Thus, in the first example, the second step corresponds to the adjustment step.

In the second example, both the first portion 50A of the first protective layer 51 and the first portion 50A of the second protective layer 52 may be polished. In the first step, the first protective layer 51 covering the resistor layer 40 and the electrode layer 30 is formed. In the second process, the first portion 50A of the first protective layer 51 is polished. In the third step, the second protective layer 52 is formed. In the fourth process, the first portion 50A of the second protective layer 52 is polished. The height Hp2 after the fourth step may be equal to or greater than the height Hp1 of the first portion 50A from the main surface 11 of the substrate 10, where the height Hp2 is the height of the portion of the second portion 50B of the protective layer 50 adjacent to the downstream side of the first portion 50A in the sub-scanning direction Y from the main surface 11 of the substrate 10. In this way, in the second example, the first step and the second step correspond to the adjustment step, respectively.

In the method of manufacturing the thermal head 1 according to the first embodiment, the protective layer 50 is polished, but the present invention is not limited thereto, and the resistor layer 40 may be polished. In this case, the resistor layer forming step includes a first step and a second step. The first step is a step of: a step of forming the resistor layer 40 by thick-film printing a paste containing ruthenium oxide so as to straddle the plurality of first strip portions 33 of the common electrode 31 of the electrode layer 30 and the plurality of second strip portions 36 of the individual electrodes 32, and then firing the thick-film printed paste. The second step is a step of polishing the top portion 40A of the resistor layer 40. In the resistor layer 40 after the second step, the height of the resistor layer 40 from the main surface 11 of the substrate 10 corresponding to the top portion 21A of the glaze 21 is equal to the height of the portion of the resistor layer 40 on the downstream side in the sub-scanning direction Y from the main surface 11 of the substrate 10 corresponding to the top portion 21A of the glaze 21. On the other hand, the second step can be omitted from the protective layer forming step. In the protective layer 50 formed by the protective layer forming process, the height of the top portion 21A of the first portion 50A corresponding to the glaze 21 is equal to the height of the portion of the second portion 50B adjacent to the first portion 50A in the sub-scanning direction Y from the main surface 11 of the substrate 10.

In each of the above embodiments, the second protective layer 52 may be omitted from the protective layer 50. In this case, the first face 50AS of the first section 50A and the second face 50BS of the second section 50B are respectively constituted by the surfaces of the first protective layer 51.

In the first embodiment, as shown in fig. 21, the thickness of the resistor layer 40 may be larger than the thickness of the first protective layer 51. In fig. 21, the thickness of the resistor layer 40 may be larger than the thickness of the second protective layer 52. In fig. 21, the thickness of the resistor layer 40 is smaller than the sum of the thickness of the first protective layer 51 and the thickness of the second protective layer 52. The protective layer 50 has a third protective layer 53. The third protective layer 53 covers a portion on the downstream side in the sub-scanning direction Y from the portion of the first protective layer 51 formed on the top portion 40A of the resistor layer 40. The third protective layer 53 is formed, for example, to have a height Hp2 equal to a height Hp1, where Hp2 is the height from the main surface 11 of the substrate 10 of a portion (second face 50BS) of the surface 50BT of the second portion 50B of the protective layer 50 adjacent to the downstream side of the first portion 50A in the sub-scanning direction Y, and the height Hp1 is the height from the main surface 11 of the substrate 10 of the first face 50AS of the first portion 50A.

In the first embodiment, at least one of the first protective layer 51 and the second protective layer 52 may have a multilayer structure in which a plurality of layers are stacked. In this case, the first face 50AS of the first portion 50A and the second face 50BS of the second portion 50B are respectively constituted by the outermost surfaces of the second protective layer 52. In the protective layer forming step, the number of layers forming at least one of the first protective layer 51 and the second protective layer 52 may be adjusted so that the height Hp2 is equal to the height Hp1, where Hp2 is the height from the main surface 11 of the substrate 10 of the portion (second surface 50BS) of the surface 50BT of the second portion 50B of the protective layer 50 adjacent to the downstream side of the first portion 50A in the sub-scanning direction Y, and the height Hp1 is the height from the main surface 11 of the substrate 10 of the first surface 50AS of the first portion 50A. In one example, the number of layers of the second portion 50B is greater than the number of layers of the first portion 50A. In addition, the number of layers of the third portion 50C is greater than that of the first portion 50A.

In the second embodiment, as shown in fig. 22, the thickness of the resistor layer 40 may be larger than that of the first protective layer 51. In fig. 22, the thickness of the resistor layer 40 is thicker than the thickness of the second protective layer 52. In fig. 22, the thickness of the resistor layer 40 is smaller than the sum of the thickness of the first protective layer 51 and the thickness of the second protective layer 52. The protective layer 50 has a third protective layer 53. The third protective layer 53 covers a portion on the downstream side in the sub-scanning direction Y from the portion of the first protective layer 51 formed on the top portion 40A of the resistor layer 40. I.e. the third protective layer 53 covers the top 21A of the glaze 21. The third protective layer 53 is formed, for example, to have a height Hp3 equal to a height Hp1 where Hp3 is the height of the portion (second face 50BS) of the surface 50BT of the second portion 50B of the protective layer 50 formed on the top 21A of the glaze 21 from the main face 11 of the substrate 10 and the height Hp1 is the height of the first face 50AS of the first portion 50A from the main face 11 of the substrate 10.

Claims

1. A thermal print head, comprising:

a substrate having a major face;

a glaze which is formed on a main surface of the substrate so as to extend in a main scanning direction, and has an arc-shaped cross-sectional shape cut by a plane orthogonal to the main scanning direction;

a resistor layer formed on the glaze so as to extend in the main scanning direction;

an electrode layer comprising a glaze electrode layer formed on the glaze; and

a protective layer covering the resistor layer and the electrode layer,

the protective layer has a first portion and a second portion,

the first portion is formed on the resistor layer and has a first surface whose height from the main surface is a first height,

the second portion is disposed on a downstream side in the sub-scanning direction from the first portion and has a second surface disposed at a position where a height from the main surface is equal to or greater than the first height.

2. The thermal print head of claim 1, wherein:

the second portion has a thickness greater than a thickness of the first portion.

3. The thermal print head of claim 2, wherein:

the second portion is a multi-layer structure,

the number of layers of the second portion is greater than the number of layers of the first portion.

4. The thermal print head of claim 1, wherein:

the protective layer has a third portion arranged on an upstream side in the sub-scanning direction from the first portion,

the first portion has a thickness thinner than a thickness of the third portion.

5. The thermal print head of claim 1, wherein:

the resistor layer is disposed on an upstream side in the sub-scanning direction from a top of the glaze.

6. The thermal print head of claim 5, wherein:

the top of the resistor layer is formed to be biased to the upstream side in the sub-scanning direction.

7. The thermal print head of claim 1, wherein:

including glass layers formed on the principal surface on the upstream side and the downstream side in the sub-scanning direction of the glaze,

the electrode layer includes a portion formed on the glass layer,

the electrode layer includes:

a common electrode having a plurality of first strip portions extending in the sub-scanning direction and arranged at intervals from each other in the main scanning direction, and a connecting portion extending in the main scanning direction and connecting the plurality of first strip portions;

an individual electrode having a second strip-shaped portion extending in the sub-scanning direction,

the first belt-shaped portions and the second belt-shaped portions are arranged so as to overlap when viewed in the main scanning direction, and the first belt-shaped portions and the second belt-shaped portions are alternately arranged in the main scanning direction.

8. The thermal print head of claim 7, wherein:

the plurality of first strip-shaped portions and the plurality of second strip-shaped portions each have a portion constituted by the glaze electrode layer,

the resistor layer is formed across the glaze electrode layer.

9. The thermal print head of claim 7, wherein:

when viewed from the thickness direction of the substrate, a distance between a front end edge of the first band-shaped portion and the resistor layer in the sub-scanning direction is smaller than a distance between a front end edge of the second band-shaped portion and the resistor layer in the sub-scanning direction.

10. The thermal print head of claim 1, wherein:

the electrode layer contains gold.

11. The thermal print head of claim 1, wherein:

the resistor layer contains ruthenium oxide.

12. The thermal print head of claim 1, wherein:

the glaze contains amorphous glass.

13. The thermal print head of claim 1, wherein:

the substrate comprises alumina.

14. A thermal print head according to any one of claims 1 to 13, wherein:

the protective layer has: a first protective layer covering the resistor layer and the electrode layer; and a second protective layer covering the first protective layer,

the second protective layer is disposed at a portion corresponding to the glaze.

15. A method of manufacturing a thermal print head, comprising:

a glaze forming step of forming a glaze on a main surface of a substrate;

a glaze electrode layer forming step of forming a glaze electrode layer on the glaze;

a resistor layer forming step of forming a resistor layer on the glaze; and

a protective layer forming step of forming a protective layer covering the glaze electrode layer and the resistor layer,

the protective layer has a first portion formed on the resistor layer and having a first surface having a first height from the main surface, and a second portion arranged on a downstream side in a sub-scanning direction from the first portion,

the protective layer forming step includes an adjustment step of forming a second surface on the second portion, the second surface being disposed at a position where a height from the main surface is equal to or greater than the first height.

16. The method of manufacturing a thermal print head according to claim 15, wherein:

the adjusting step is performed by polishing the first portion so that the height of the second surface of the second portion from the main surface is equal to or greater than the first height.

17. The method of manufacturing a thermal print head according to claim 15, wherein:

the adjusting step covers the second portion with another protective layer so that the height of the second portion from the main surface is equal to or greater than the first height.

18. A method of manufacturing a thermal print head according to any one of claims 15 to 17, wherein:

in the resistor layer forming step, the resistor layer is formed by thick-film printing a paste and then firing the thick-film printed paste.

19. A method of manufacturing a thermal print head, comprising:

a glaze forming step of forming a glaze on a main surface of a substrate;

a resistor layer forming step of forming a resistor layer on the glaze; and

in the resistor layer forming step, the resistor layer is formed on an upstream side in a sub-scanning direction from a top of the glaze.

20. The method of manufacturing a thermal print head according to claim 19, wherein: