Incremental printing of symbolic information – Thermal marking apparatus or processes – Specific resistance recording element type
Reexamination Certificate
2000-05-08
2001-05-08
Tran, Huan (Department: 2861)
Incremental printing of symbolic information
Thermal marking apparatus or processes
Specific resistance recording element type
Reexamination Certificate
active
06229557
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a thermal print head composed of a heating board and a radiating plate, detailedly relates to a thermal print head provided with an identification mark for positioning when a heating board is bonded to a radiating plate.
BACKGROUND ART
Heretofore, this type of thermal print head is composed by attaching a ceramic heating board onto the upper surface of a metallic radiating plate. A heating resistor for printing, a common electrode pattern and an individual electrode pattern are formed on the surface of the heating board and plural IC chips for driving are mounted. In case the heating board having the configuration described above is attached to the radiating plate, an adhesive and a pressure sensitive adhesive tape are generally used, however, in any case, precise positioning is required and particularly, to position precisely in the longitudinal direction of the heating board, that is, in the direction of the x-axis which is a direction in which the heating resistor is arranged, heretofore, a first dot part (the leading end) and a last dot part (the trailing end) of the heating resistor linearly formed on the heating board are based.
That is, the first dot part and the last dot part of the heating resistor are directly recognized as a binary number by a camera and others, the heating board is precisely set on the radiating plate and is bonded based upon it.
However, recently, the demand of a thermal print head wherein a heating resistor is covered with a conductive protective coat is increased and a problem that precision in bonding between a heating board and a radiating plate decreases because such a conductive protective coat is formed occurs.
That is, as a heating resistor is generally black, while a conductive protective coat is also approximately black, it is difficult to recognize the first dot part and the last dot part of the heating resistor by a camera and as a result, misregistration by wrong recognition occurs.
Therefore, it is considered that an identification mark different from a heating resistor is required and is based, however, wrong recognition is caused depending upon the shape of a mark and satisfactory bonding precision is not achieved. The object of the invention is to provide a thermal print head wherein an identification mark for positioning enabling solving such problems is provided.
DISCLOSURE OF THE INVENTION
To solve the problems, a first aspect of the invention is based upon a thermal print head wherein a heating board on the surface of which a heating resistor for printing is formed is attached on the upper surface of a radiating plate and is characterized in that the heating board is provided with an identification mark having the vertical side for an orientation arranged perpendicularly to a direction in which heating resistor is arranged so that the identification mark functions as the orientation when the heating board is attached to the radiating plate.
Therefore, as a first dot part and a last dot part of the heating resistor can be more definitely recognized than they are directly recognized as a binary number by a camera, positioning when the heating board is attached to the radiating plate can be precisely performed. Particularly, even if the identification mark is formed using gold foil and others which is hardly recognized when the parts are recognized as a binary number, a longitudinal reference line formed by the vertical side definitely appears and wrong recognition can be possibly prevented.
Also, a second aspect of the invention is based upon the thermal print head according to the first aspect of the invention and is characterized in that the heating resistor is covered with a protective coat. That is, as positioning can be precisely performed even if it is difficult to recognize the heating resistor as a binary number by a camera because of the protective coat, positional precision for attaching the heating board onto the radiating plate can be enhanced.
Also, a third aspect of the invention is based upon the thermal print head according to the first aspect of the invention and is characterized the identification mark is provided in a position except the protective coat.
Therefore, even if the identification mark is formed in approximately the same color as that of the protective coat, a precise positional reference can be acquired.
Also, a fourth aspect of the invention is based upon the thermal print head according to the first aspect of the invention and is characterized in that as for the identification mark, the vertical side is provided in only one location. Therefore, there is no possibility that another vertical side is recognized as a reference position by mistake.
A fifth aspect of the invention is based upon the thermal print head according to any of the first to third aspects of the invention and is characterized in that the identification mark is composed of an X reference line formed by the vertical side and a Y reference line formed by the side perpendicular to the vertical side.
According to such configuration, alignment not only in the longitudinal direction (the direction of X) but in the direction of Y can be achieved and extremely precise alignment is enabled.
A sixth aspect of the invention is based upon the thermal print head according to the first aspect of the invention and is characterized in that the identification mark is made of a thick film printed pattern.
A seventh aspect of the invention is based upon the thermal print head according to the first aspect of the invention and is characterized in that the identification mark is made of a thin film pattern.
An eighth aspect of the invention is based upon the thermal print head according to the sixth or seventh aspect of the invention and is characterized in that the identification mark is formed in a process for forming an electrode pattern. According to such configuration, the identification mark can be formed at the same time that the electrode pattern is formed without requiring another process and further, as relative positioning is applied to the electrode pattern by a mask, extremely precise positioning is enabled.
Also, a ninth aspect of the invention is based upon the thermal print head according to any of the first to the third aspects of the invention and is characterized in that the identification mark is a polygon having the vertical side as one side. Therefore, in case the polygon is recognized as a binary number, the plane is clearly shown and the vertical side to be a reference can be definitely recognized. Also, for example, in the case of a polygon having the side perpendicular to the vertical side, positioning not only in the longitudinal direction of the heating board but in the direction of the width can be precisely performed.
Further, a tenth aspect of the invention is based upon the thermal print head according to any of the first to third aspects of the invention and is characterized in that the identification mark is a semicircle having the vertical side as one side. Therefore, the area of the mark to acquire precise recognition can be reduced up to the required minimum limit, the quantity of pasted gold, aluminum and others for forming the mark can be reduced and the cost can be reduced.
An eleventh aspect of the invention is based upon a method of mounting the heating board on the surface of which the heating resistor for printing is formed on the radiating plate and forming the thermal print head and is characterized in that a process for forming the heating board on which the heating resistor for printing, the identification mark having the vertical side perpendicular to a direction in which the heating resistor is arranged and the electrode pattern connected to the heating resistor are formed and a process for aligning and fixing the heating board on the radiating plate using the vertical side of the identification mark as a positioning reference line are included. Therefore, as the first dot part and the last dot part of the heating resistor can be more definitely recog
Morgan & Lewis & Bockius, LLP
Rohm & Co., Ltd.
Tran Huan
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