This application claims priority from Japanese Patent Application No. 2002-206219 filed Jul. 15, 2002, which is incorporated hereinto by reference.
1. Field of the Invention
The present invention relates to a printing head for ejecting ink, and an ink jet printing apparatus which performs printing by means of the printing head. More particularly, the present invention relates to electrical connections in the circuit boards, etc. of the printing head.
2. Description of the Related Art
Ink jet printers or the like, as apparatuses in which printing is performed by ejecting ink onto a printing medium, are widely used. Such an ink jet printing apparatus includes a printing head for ejecting the ink Besides, signals such as a head drive signal are exchanged between the printing head and an apparatus main body, and the electric power of a power source is supplied from the apparatus main body to the printing head.
As shown in
The body 18 is so configured that the above portions such as the ink supply portion 180 are unitarily molded by, for example, a resin. The ink supply portion 180 has a recess portion 182G for receiving the supporting board 20 therein. The bottom of the recess portion 182G is a surface used as a joint surface 183 on which the supporting board 20 is bonded. As shown in
The substrate forming the printing element board 10 is a thin film of silicon material having a thickness of 0.5 mm-1.0 mm. Besides, the substrate is formed with an opening which communicates with the above-mentioned ink supply port 184 through the opening 20a of the supporting member 20, as shown in FIG. 5. In addition, heaters and partition walls dividing the heaters are respectively disposed in correspondence with a plurality of ink ejection orifices on both the sides of the opening 10c on the substrate. Thus, the ink supplied from the ink tank IT is fed into respective ink paths provided with the corresponding heaters.
As shown in FIG. 5 and
The supporting board 20, which is arranged between the printing element board 10 and the joint surface 183 of the recess portion 182G in the ink supply portion 180, is formed in the shape of a rectangular plate, as shown in FIG. 5 and
As shown in
In disposing in the body 18 the printing element board 10 to which the printed wiring board 30 is connected, the first joint surface 20Sb of the support board 20 is initially bonded to the predetermined position of the joint surface 183 by an adhesive. Subsequently, as shown in
In the printing head configured as described above, when heater drive signals corresponding to printing information are fed to the heaters of the printing element board 10 through the printed wiring board 30, the heater generates heat and thus an air bubble is generated in the ink, and thereby the ink is ejected by the pressure of the air bubble.
An example of the prior-art printing head as described above is shown in Japanese Patent Application Laid-open No. 07-144418(1995). However, the electrical connections of such a prior art between the printing element board and the printed wiring board has involved several technical problems as stated below.
In the first place, since the TAB method is employed as a method for connecting electrode wiring lines of both the boards, multi-layering of the electrode wiring lines in the printed wiring board is difficult, and the multi-layering is very difficult especially in case of arranging electrode wiring lines at a high density. Therefore, the electrode wiring lines of, for example, the above-mentioned flexible board (printed wiring board) are often laid as wiring lines of single layer. As a result, the number of the wiring lines in the flexible board has a certain limitation, and the sorts of signals which can be fed to the printing head through the flexible board are also limited.
In order to cope with the above drawback, it is considered to heighten a wiring density with the intention of increasing the number of wiring lines, but the intervals of the wiring lines need to be shorten accordingly (to, for example, 100 μm or less). Since, in this case, the wiring lines are formed at the very small intervals, a process for the formation of wiring lines sometimes becomes complicated.
Besides, since the electric power consumption of the printing head employing the above heaters is comparatively large (several tens W-about 100 W), the width of wiring line need to be maintained at a sufficient scale, in case of feeding the corresponding electric power without increasing the number of the wiring lines. This incurs the problem that the wiring board enlarges to increase the size of the printing head.
Secondly, in the TAB method, electrodes are connected to exposed electrode terminals at a connection part between the printed wiring board and the printing element board. Consequently comparatively rigid sealing needs to be performed by increasing an amount of a sealing material. As a result, the sealing material is deposited to form a convex portion on an ejection orifice surface of the printing head. In consequence, the spacing between the printing head and printing paper needs to be held at, at least, a certain magnitude, and the flight distances of ejected ink droplets enlarge to that extent and form a factor for hampering an improvement of a printing precision.
The above problems will be concretely explained with reference to
For the simplification of the description,
In the wiring layout, when the wiring lines 31 on the right side and the wiring lines 31 on the left side as are respectively symmetric with respect to the printing element board 10 feed the same signals or power levels, they are made common In prior-art cases, however, they have been made common on the side of the apparatus main body. More specifically, since the connections of the wiring lines 31 adopt the TAB method, these wiring lines 31 are difficult to be multilayered, and they cannot be made common in the vicinity of the connection parts with the printing element board 10. Therefore, the flexible board is mostly formed bearing the respective right and left wiring lines as the separate ones. As a result, the sorts of signals, etc. cannot be increased, or the width of the board itself needs to be enlarged for the purpose of ensuring predetermined sorts of signals, etc.
Further, as seen from
An object of the present invention is to provide a printing head and an ink jet printing apparatus of high reliability in which the number or density of the electrode wiring lines of a wiring board for feeding signals, etc. to a printing element board can be increased by a simple arrangement.
In the first aspect of the present invention, there is provided a printing head for ejecting ink, comprising:
a printing element board including an energy generating element for generating energy used for ejecting the ink;
a wiring board used for supplying an electric signal or an electric power from an apparatus main body to the printing element board, the wiring board including an electrode wiring line connected with an electrode of the printing element board to supply the electric signal or an electric power; and
a supporting member supporting the printing element board, the supporting member being formed with an electrode wiring line for connecting the electrode wiring lines, which supply the electric signal of the same kind or the electric power of the same kind, with each other among the electrode wiring lines connected with the electrode of the printing element board.
Preferably, the connection of the electrode wiring line of the wiring board with the electrode of the printing element board may be made in a state in which the electrode wiring line is entirely covered with the wiring board.
In the second aspect of the present invention, there is provided an ink jet printing apparatus which employing a printing head to eject ink to a printing medium for performing printing,
wherein the printing head comprises:
Preferably, the connection of the electrode wiring line of the wiring board with the electrode of the printing element board may be made in a state in which the electrode wiring line is entirely covered with the wiring board.
According to the above configuration, in the wiring board for feeding signals and the like to the printing element board, a plurality of electrode wiring lines of an identical sort, for example, for feeding supply power are interconnected by the electrode wiring line in the supporting member, and hence, a part of the electrode wiring lines of the identical sort for feeding the power can be omitted in the wiring board, whereby a space for laying the other electrode wiring lines can be relatively enlarged in the wiring board. In other words, according to the present invention, the supporting member for supporting the printing element board is utilized to be provided with an electrode wiring line for making common the electrode wiring lines in the wiring board, whereby the electrode wiring lines in the wiring board can be, in effect, multilayered. Moreover, the electrode wiring lines of the wiring board are connected with the electrodes of the printing element board in a state where they are entirely covered within the wiring board itself, so that the quantity of the sealant used for connections can be lessened.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.
Embodiments of the present invention will be described in detail with reference to the drawings.
(Embodiment 1)
The printing head of this embodiment is similar to the printing head shown in
A supporting board 20 serving as a supporting member is an insulating board, and an electrode wiring line 21 is formed on the supporting board 20.
In this manner, an electrode wiring line is laid on the supporting member so that certain wiring lines of the flexible board which are connected with electrode terminals of the printing element board are made common. Thus, it is possible to vacate a region which the flexible board has heretofore required for disposing one of the electrode wiring lines 31 to be made common in the embodiment. It is consequently permitted to lay a larger number of electrode wiring lines or make the width of the electrode wiring line per se, without enlarging the width of the flexible board.
Besides, the connections between bump electrodes of the printing element board and the wiring lines of the flexible board are not made in a state where the electrode wiring lines are exposed as in the prior art, and therefore, a large quantity of sealant is not required. As a result, comparatively large convex portion can be prevented from being formed on the ejection orifice surface of the printing head, and then the distance between the printing head and printing paper can be set small.
(Embodiment 2)
This embodiment relates to an aspect in which the electrode wiring line 21 which is formed on the supporting board 20 is formed in multilayered fashion
As shown in these figures, only those parts of the electrode wiring line 21 which are connected with wiring lines 31 are formed as double layers. More specifically, the part of the electrode wiring line 21 other than the parts thereof connected with the wiring lines 31 is buried in the supporting board 20, and only connection parts 21A thereof are exposed. Thus, the connections between the electrode wiring line 21 and the wiring lines 31 can be facilitated.
Incidentally, since the multi-layering of the electrode wiring line 21 in the supporting board 20 is comparatively easy in a manufacturing process, more complicated arrangement of wiring line can be achieved.
(Embodiment 3)
This embodiment relates to a modification to Embodiment 2 described above, and consists in that the flexible board is substantially entirely covered with an insulating board which is of the same material as that of the supporting board.
As shown in these figures, a supporting board 20 and an insulating board 22 of the same material as that of this supporting board 20 are disposed so as to sandwich a flexible board 30 therebetween. Thus, the board 22 forms the outermost surface of the printing head. That is, a smooth surface is formed around the ejection orifice surface of the printing head by the board 22.
As a result, a cap for capping in a non-printing mode abuts favorably on the printing head owing to the smooth surface.
Referring to
The carriage 200 is held in slidable engagement with a guide shaft 202, and the driving force of a carriage motor 203 is transmitted through a belt extended over pulleys 205, 206, whereby the carriage 200 can move for scanning along the guide shaft 202. Recovery units 212 each of which includes a cap or the like for executing a recovery process for the corresponding printing head are disposed at one end of a scanning range of the printing head based on the carriage 200. Besides, printing paper P is fed into a printing region within the scanning range of the printing heads, intermittently in synchronism with the scanning of the printing heads. The paper feed is permitted by a pair consisting of a conveying roller 207 and a pressing roller 208, and a pair consisting of a conveying roller 209 and a pressing roller 210 as are respectively disposed on the upper stream side and lower stream side of the printing region.
Incidentally, one form of the printing head to which the present invention is effectively applied is such that film boiling is induced in ink by utilizing thermal energy generated by an electro-thermal transducer, and that the ink is ejected by the pressure of air bubbles generated by the boiling.
As is apparent from the above description, according to the embodiments of the present invention, in the wiring board for feeding signals and the like to the printing element board, a plurality of electrode wiring lines of an identical sort, for example, for feeding supply power are interconnected by an electrode wiring line in the supporting member, and hence, a part of the electrode wiring lines of the identical sort for feeding the power can be omitted in the wiring board, whereby a space for laying the other electrode wiring lines can be relatively enlarged in the wiring board. In other words, according to the present invention, the supporting member for supporting the printing element board is utilized to be provided with an electrode wiring line for making common the electrode wiring lines in the wiring board, whereby the electrode wiring lines in the wiring board can be, in effect, multilayered. Moreover, the electrode wiring lines of the wiring board are connected with the electrodes of the printing element board in a state where they are entirely covered within the wiring board itself, so that the quantity of the sealant used for connections can be lessened.
As a result, the number or density of the electrode wiring lines of the wiring board for feeding signals, etc. to the printing element board can be increased by a simple configuration.
The present invention has been described in detail with respect to preferred embodiments, and it will now be apparent from the foregoing to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspect, and it is the intention, therefore, in the appended claims to cover all such changes and modifications as fall within the true spirit of the invention.
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2002-206219 | Jul 2002 | JP | national |
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20040017436 A1 | Jan 2004 | US |