Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
1998-06-16
2001-02-27
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C219S543000
Reexamination Certificate
active
06193365
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a head of a hot melt type inkjet printer, and more particularly to a sheet shaped heating device used for a head of a hot melt type inkiet printer.
2. Description of the Related Art
A hot melt type inkiet head has a plurality of nozzle heads corresponding to a plurality of colors of inks actually used for printing, respectively. Each of the nozzle heads has a large number of nozzle holes. In such a hot melt type inkiet head, when printing, solid hot melt inks are melted by heat, and then, the hot melt inks in the liquid state are ejected through the nozzle holes. Therefore, it is necessary to heat up the inks quickly at the start of printing, and keep temperature of the inks at a predetermined high temperature during printing. Here, a performance of an ink ejection is sensitively changed with temperature of inks. If temperature of each nozzle head is not uniform, ejection speed of inks irregularly varies. As a result, printing quality is reduced. Therefore, in order to enhance the printing quality, it is necessary to apply heat to each nozzle head suitably, and that an optimum temperature distribution is set for each nozzle head. In order to apply heat to each nozzle head, the hot melt type inkjet head has a sheet shaped heater.
A sheet shaped heater is typically used as a heater for the hot melt type inkiet head. The sheet shaped heater has an insulating sheet made of polyimide or the like. On the insulating sheet, a meandering wiring pattern is formed. Width and length of the wire of the wiring pattern are designed so as to set a certain wattage density in each part of the wire. The sheet shaped heater is attached near the nozzle heads, and applies heat to the nozzle heads in order to set an optimum temperature distribution for each nozzle head. More concretely, the sheet shaped heater is bonded to a mounting part of the inkiet head located near the nozzle heads by using an adhesive etc., in a condition that a surface of the sheet shaped heater abuts a surface of the mounting part. Therefore, heat generated by the wiring pattern of the sheet shaped heater is conduct to the nozzle head through the mounting part.
However, the surface of the mounting part is flat and relatively hard, whereas the surface of the sheet shaped heater is easy to curve, since the insulating sheet made of polyimide or the like is soft and flexible. In case that the surface of the sheet shaped heater has curved and a concave portion has been formed on it, if the surface of the sheet shaped heater is bonded to the surface of the mounting part, an enclosed space is formed between them, and air is confined in the enclosed space.
Furthermore, if the enclose space is formed in the vicinity of the middle of the surface of the sheet shaped heater, it is difficult to remove the air and the enclosed space.
Moreover, if the enclosed space has been formed, the surface of the sheet shaped heater is partially separate from the surface of the mounting part. Hence, heat generated by the wiring pattern is not completely conducted to the nozzle head through the mounting part. Accordingly, thermal efficiency is reduced, a temperature distribution is dispersed, and printing quality is reduced.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a hot melt type inkjet head and a heating device to be used for a hot melt type inkjet head, wherein a surface of the heating device can be completely bonded to a surface of a mounting part of the hot melt type inkjet head without a space between them, and heat can be completely conducted to the mounting part.
According to the present invention, the aforementioned object can be achieved by a sheet shaped heating device attached on a contact surface of a mounting part of a hot melt type inkjet head for applying heat to the mounting part in order to heat hot melt ink in the hot melt type inkjet head, the sheet shaped heating device having: an insulating sheet having an attaching surface to be attached on the contact surface of the mounting part and a wiring surface located opposite to the attaching surface; and a heating element disposed on the wiring surface of the insulating sheet for generating heat, wherein at least one air passage passing through the insulating sheet is formed.
Namely, the sheet shaped heating device is attached on the contact surface of the mounting part of the hot melt type inkjet head. Therefore, when the heating element generates heat, the heat is conducted to the mounting part through the insulating sheet. Therefore, the hot melt ink in the hot melt type inkiet head is heated.
Here, the air passage is formed through the insulating sheet. Therefore, when the sheet shaped heating device is attached on the contact surface of the mounting part, it is possible to let air escape from between the attaching surface of the insulating sheet and the contact surface of the mounting part thought the air passage. Thus, it is possible to remove air and a space from between them. Accordingly, it is possible to bond the attaching surface of the heating device to the contact surface of amounting part completely. Therefore, heat generated by the heating element can be completely conducted to the mounting part.
Otherwise, it is preferable that the air passage is a hole. Furthermore, the air passage may be a hole shaped like a slit extending along the attaching surface of the insulating sheet. Moreover, the air passage is located in a vicinity of a middle of the attaching surface of the insulating sheet. Therefore, it is possible to let air escape advantageously.
Moreover, a sheet shaped insulating cover may be disposed on the wiring surface of the insulating sheet for covering the heating element. In this case, the air passage is formed through the insulating sheet and the sheet shaped insulating cover. Therefore, not only the attaching surface of the insulating sheet but also a surface of the insulating cover can be alternatively attached on the contact surface of the mounting part. Accordingly, it is possible to improve flexibility of design.
According to the present invention, the above mentioned object can be also achieved by an hot melt type inkjet head having: an ink tank for storing hot melt ink; a nozzle for ejecting the hot melt ink; an ink supplying member having an inside wall defining an ink channel for supplying the hot melt ink from the ink tank to the nozzle therethrough, and having an outside contact surface located opposite to the inside wall; a sheet shaped heating device attached on the outside contact surface of the ink supplying member for applying heat to the hot melt ink passing through the ink channel, the sheet shaped heating device having: an insulating sheet having an attaching surface to be attached on the outside contact surface of the ink supplying member and a wiring surface located opposite to the attaching surface; and a heating element disposed on the wiring surface of the insulating sheet for generating heat, wherein at least one air passage passing through the insulating sheet is formed.
Therefore, when the sheet shaped heating device is attached on the outside contact surface of the ink supplying member, it is possible to let air escape from between the attaching surface of the insulating sheet and the outside contact surface of the ink supplying member thought the air passage. Thus, it is possible to remove air and a space from between them. Accordingly, it is possible to bond the attaching surface of the heating device to the outside contact surface of the ink supplying member completely.
The nature, utility, and further feature of this invention will be more clearly apparent from the following detailed description with respect to preferred embodiments of the invention when read in conjunction with the accompanying drawings briefly described below.
REFERENCES:
patent: 5017941 (1991-05-01), Drake
patent: 5424767 (1995-06-01), Alavizadeh et al.
patent: 5635964 (1997-06-01), Burr et al.
patent: 5939206 (1999
Brother Kogyo Kabushiki Kaisha
Hsieh Shih-Wen
Le N.
Oliff & Berridg,e PLC
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