1. Field of the Invention
The present invention relates to a liquid ejecting head, an ejecting element substrate and a liquid ejecting apparatus for ejecting liquids such as ink toward various kinds of media.
2. Description of the Related Art
Recently because of a requirement for a high-speed print, ejection opening arrays arrayed in a liquid ejecting head are required to be lengthened and arrayed in a multiple array and an ejecting element substrate is required to be miniaturized, so that a high concentration of the ejection opening arrays is required and a problem due to the high concentration occurs.
Japanese Patent Laid-Open No. 2005-193579 discloses the solution measure to a problem that a heat distribution differs in a print element substrate and the ejection performance (ejection amount) changes due to a difference in the influence of heat received, thus degrading the print quality. According to the solution measure disclosed in Japanese Patent Laid-Open No. 2005-193579, ejecting inks of a light color to an ejection opening array arranged in a place within the ejecting element substrate susceptive to the thermal influence suppresses the degradation of the print quality visually.
However, there occurs a new problem that cannot be solved by the method disclosed by Japanese Patent Laid-Open No. 2005-193579. When a temperature of the ejecting element substrate during the ejecting partially increases, the viscosity of the liquid decreases, increasing a refill speed of the liquid. As a result, there are some cases where the liquid overflows from an ejection opening to stay on the surface of the ejection opening, so that an ejection defect such as non-ejection occurs to degrade the print quality.
Therefore the present invention provides a liquid ejecting head, an ejecting element substrate and a liquid ejecting apparatus that can suppress degradation in print quality.
A liquid ejecting head according to the present invention comprises a plurality of ejection openings for ejecting liquids, flow passages communicated with the ejection openings, and energy generating elements for generating energy used for ejection of the liquids from the ejection openings, wherein the ejection opening closer to the center in an arrangement area where the ejection openings are arranged is communicated with the flow passage having the higher flow resistance.
With the present invention, there can be realized the liquid ejecting head, the ejecting element substrate and the liquid ejecting apparatus that can suppress the degradation in print quality.
Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
Hereinafter, an explanation will be made of a first embodiment of the present invention with reference to the accompanying drawings.
The support member 9 is provided with supply ports and a liquid chamber to which liquids (hereinafter, called ink as well) are supplied through the housing 10. The liquid chamber inside the support member 9 is connected to the supply port 7 disposed in each of ejection opening arrays in the ejecting element substrate 4. The ejection opening array disposed in the ejecting element substrate 4 is formed by ejection openings 12 as holes communicated with foaming chambers 17 which is a pressure room retaining inks to be ejected lining up (in a predetermined direction).
The liquid ejecting head 1 uses heat generated from a heating resistance element (energy generating element) with application of electrical energy as energy for ejecting the ink. The heat generation causes film boiling of the ink to eject the ink from the ejection openings 12 with the foaming energy. At printing, the liquid ejecting head 1 reciprocates in an arrow α direction in
The common liquid chamber 18 is provided with a filter in a projecting shape (columnar shape) for preventing dusts from entering in an inlet (connecting portion between the common liquid chamber and the flow passage) of the flow passage communicated with the foaming chamber 17. In the present embodiment, as illustrated in
As described above, in the ejecting element substrate during printing, heat is generated accompanying the printing. The generated heat is transmitted to the periphery of the ejecting element substrate and is released through the ejecting element substrate and the support member. However, the amount of heat release per unit time is limited, and therefore when the amount of heat generation per unit time is large as at the high-speed printing, the heat release cannot be sufficiently performed, thus increasing the temperature of the ejecting element substrate partially (in the central part). Particularly among the ejection opening arrays on the ejecting element substrate, the heat generated in the ejection opening array close to the center of the ejecting element substrate is difficult to be released, therefore increasing the temperature in the central part of the ejecting element substrate to be high. When the temperature in the central part of the ejecting element substrate becomes high in this way, the ink viscosity is reduced to increase a refill speed of ink. Therefore the ink overflows from the ejection opening and stays in the periphery of the ejection opening surface, thereby generating an ejection defect and degrading the print quality. As a result, the measure for preventing the print quality from degrading is required.
Therefore in the present embodiment, among the three ejection opening arrays (arrangement area) in the ejecting element substrate 4, a flow resistance of the flow passage 19 corresponding to the B array positioned in the middle (in a direction crossing a predetermined direction where the ejection openings are arrayed) is made larger than a flow resistance of the flow passage 19 corresponding to each of the other ejection opening arrays (A array, C array). In the ejection opening array of each of the A array and the C array, the width of the flow passage 19, as illustrated in
In this way, in the ejection opening array of the B array, the flow resistance in the flow passage 19 is made large by narrowing the width of the flow passage 19. By thus increasing the flow resistance in the flow passage 19 to be large, even when the temperature in the ejection opening array of the B array becomes high to reduce the ink viscosity, the refill speed of the ink does not increase because of the high flow resistance, resulting in no overflow of the ink from the ejection opening. Therefore the generation of the ejection defect can be suppressed to suppress the degradation in print quality. It should be noted that the structure in which the flow resistance of the flow passage 19 in the ejection opening array of the B array is made large is designed in such a manner that the refill speed can be maintained as a sufficient speed even at a low temperature. In regard to specific dimensions of the flow passages, a flow passage width of the flow passage corresponding to the ejection opening array of each of the A array and C array is defined as 14μ and a flow passage width of the flow passage corresponding to the ejection opening array of the B is defined as 10μ.
In addition, here, the explanation is made on a condition that the ejection opening arrays of the A array and the C array have the same structure, but the flow resistance of the flow passage corresponding to the ejection opening of the flow passage of the central ejection opening array (B array) is only required to be the largest, and the other ejection opening arrays each other have not necessarily the same structure. For example, as illustrated in
In this way, in the ejecting element substrate arranged the closest to the center of the support member, the flow resistance of the flow passage corresponding to the ejection opening of the ejection opening array arranged the closest to the center of the ejecting element substrate is made high. This allows realization of the liquid ejecting head, the ejecting element substrate, and the liquid ejecting apparatus that can suppress the degradation in print quality.
Hereinafter, an explanation will be made of a second embodiment of the present invention with reference to the accompanying drawings. Since a basic structure of the present embodiment is the same as that of the first embodiment, hereinafter only a characteristic structure thereof will be explained.
In
In this way, in the ejection opening array of each of the B array and C array, a cross-sectional area of the flow passage 29 is made small by narrowing the width of the flow passage 29 to increase the flow resistance in the flow passage 29. When the flow passage resistance in the flow passage 29 is thus made large, even if the temperature in each of the B array and C array becomes high to reduce the ink viscosity, the refill speed of the ink does not increase. Therefore it is possible to suppress the generation of the ejection defect and degradation in print quality.
It should be noted that among the three arranged ejecting element substrates 24, all the ejection opening arrays of the ejecting element substrates 24 positioned other than the center thereof (in both ends of the left and right) have the same configuration (the flow resistance in the flow passage is not made high).
In addition, in the present embodiment, it is explained that the A array and D array, and the B array and C array respectively have the same structure, but the flow resistance of the flow passage of the array arranged the closest to the center thereof (B array or C array or both thereof) is only required to be the largest, and a shape of the flow passage in the other array is not particularly limited. However, it is preferable that a width of the flow passage 29 of only each of the B array and C array in the central ejecting element substrate of the support member is narrow, and the arrays of the other ejecting element substrates have the same structure. The reason is that as long as the arrays have the same design, there is a degree of freedom for color changing and the kind of the ejecting element substrates is only required to be two kinds, it is relatively less expensive at the manufacture. In addition, when the ejecting element substrates are formed in symmetry to each other, it has an advantage in a case of equally arranging a few color numbers in a plurality of arrays.
Since the ejecting element substrates A and C having the different flow passages in the ejection opening arrays in both ends in the left and right are in common, the symmetry of the liquid ejecting head is broken as a whole. Further, depending on the ink, an ink color usable in an a array of the ejecting element substrate A has to be arranged in an i array of the ejecting element substrate C, and therefore not only a degree of freedom is lowered but also in some cases there is no ink color usable. In this case, another kind of ejecting element substrate is required to be prepared, leading to an increase in cost.
However, when the ejecting element substrates A to C are all structured to maintain the common structure or the symmetry, standard deep colors of C, M and Y are arranged in symmetry in a way that inks corresponding to a array to i array correspond to C, M, PC, PBK, MBK, MBK, Gy, PM, Y, M, C. In a case of this symmetry arrangement, the liquid ejecting head can move bi-directionally for printing to realize the high speed.
In this way, in the ejecting element substrate arranged the closest to the center of the support member, the flow resistance of the flow passage corresponding to the ejection opening of the ejection opening array arranged the closest to the center of the ejecting element substrate is made high. This allows realization of the liquid ejecting head, the ejecting element substrate, and the liquid ejecting apparatus that can suppress the degradation in print quality.
Hereinafter, an explanation will be made of a third embodiment of the present invention with reference to the accompanying drawings. Since a basic structure of the present embodiment is the same as that of the first embodiment, hereinafter only a characteristic structure thereof will be explained.
It should be noted that in the present embodiment, the inlet of the flow passage communicated with the foaming chamber is narrowed by increasing the diameter of the filter to increase the flow resistance to be high, but the filter itself may be disposed closer to the inlet of the flow passage without changing the diameter of the filter to narrow the inlet of the flow passage communicated with the foaming chamber and increase the flow resistance to be high.
In this way, in the ejecting element substrate arranged the closest to the center of the support member, the flow resistance of the flow passage corresponding to the ejection opening of the ejection opening array arranged the closest to the center of the ejecting element substrate is made high. This allows realization of the liquid ejecting head, the ejecting element substrate, and the liquid ejecting apparatus that can suppress the degradation in print quality.
Hereinafter, an explanation will be made of a fourth embodiment of the present invention with reference to the accompanying drawings. Since a basic structure of the present embodiment is the same as that of the first embodiment, hereinafter only a characteristic structure thereof will be explained.
As in
It should be noted that although not illustrated herein, the flow resistance may be made large by extending not only the elongated part of the flow passage but also an entire length of the flow passage including from the ink supply passage to the foaming chamber.
In this way, in the ejecting element substrate arranged the closest to the center of the support member, the flow resistance of the flow passage corresponding to the ejection opening of the ejection opening array arranged the closest to the center of the ejecting element substrate is made high. This allows realization of the liquid ejecting head, the ejecting element substrate, and the liquid ejecting apparatus that can suppress the degradation in print quality.
Hereinafter, an explanation will be made of a fifth embodiment of the present invention with reference to the accompanying drawings. Since a basic structure of the present embodiment is the same as that of the first embodiment, hereinafter only a characteristic structure thereof will be explained.
In each of the aforementioned embodiments, only one factor out of the width of the flow passage communicated with the foaming chamber, the diameter of the filter and the length of the flow passage is changed to differentiate the flow resistance of the flow passage, but the flow resistance of a total of the flow passages leading to the foaming chamber is only required to be large. That is, the present invention may have a combination of the flow passage width, the flow passage length and the filter diameter all of which are different. It should be noted that since various variations may be conceived and are not limited to a particular one, the drawing is omitted herein.
In this way, in the ejecting element substrate arranged the closest to the center of the support member, the flow resistance of the flow passage corresponding to the ejection opening of the ejection opening array arranged the closest to the center of the ejecting element substrate is made high. This allows realization of the liquid ejecting head, the ejecting element substrate, and the liquid ejecting apparatus that can suppress the degradation in print quality.
Hereinafter, an explanation will be made of a sixth embodiment of the present invention with reference to the accompanying drawings. Since a basic structure of the present embodiment is the same as that of the first embodiment, hereinafter only a characteristic structure thereof will be explained.
In this way, in the ejecting element substrate arranged the closest to the center of the support member, the flow resistance of the flow passage corresponding to the ejection opening of the ejection opening array arranged the closest to the center of the ejecting element substrate is made high. This allows realization of the liquid ejecting head, the ejecting element substrate, and the liquid ejecting apparatus that can suppress the degradation in print quality.
Hereinafter, an explanation will be made of a seventh embodiment of the present invention with reference to the accompanying drawings. Since a basic structure of the present embodiment is the same as that of the first embodiment, hereinafter only a characteristic structure thereof will be explained.
Subsequently an explanation will be made of the most preferable arrangement of inks in this ejecting element substrate. When the refill speed is fast, non-ejection is generated due to overflow of ink at refilling. Therefore a design in which the ink having the fastest refill speed is arranged in the array of maximizing the flow resistance of the flow passage corresponding to the ejection opening array arranged in the center of the ejecting element substrate is the most preferable. By doing so, also in the print at a low temperature other than the high-speed ejection, the overflow is difficult to be generated, making occurrence of problems due thereto more difficult. Here, the fast refill speed means ink having high surface tension or ink having low viscosity.
Further, preferably ink having a slow ejection speed is arranged in the central ejection opening array having a large flow resistance of the flow passage. An example of inks may include pigment black in which the burning of carbon becomes the largest in amount on a print element. When the burning becomes large, since it is difficult for heat of the print element to be transmitted to the ink, the ejection speed is reduced. On the other hand, as an additional effect by increasing the flow resistance, there is taken an example where the resistance behind the foaming chamber becomes high, and a ratio between a resistance from the foaming chamber to the ejection opening and a resistance of the flow passage part varies to improve an ejection efficiency, so that the ejection speed is inclined to be more easily increased.
Further, even in a case of the same refill speed, it has been found out by the review that as the ejection speed is faster, the ink overflows the more remarkably to create the ejection defect. From this point as well, it is preferable that the ink having a slow ejection speed and a fast refill speed is arranged in the ejection opening array arranged in the center of the ejecting element substrate.
In addition, in regard to ink of pigment or dye used in the inkjet printer for printing photos and posters regularly, the flow resistance is a dominant factor regardless of a few difference in ink properties, and a desired effect for the solution of the problems can be obtained by application of the present invention.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2015-104876, filed May 22, 2015, which is hereby incorporated by reference wherein in its entirety.
Number | Date | Country | Kind |
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2015-104876 | May 2015 | JP | national |