The present disclosure generally relates to a liquid ejection head.
In a liquid ejection head that ejects liquid such as ink, a viscosity of the liquid near an ejection port may increase due to evaporation of volatile components in the liquid. An increment of the viscosity of the liquid may affect the ejection speed and impact accuracy of the ejected droplets. In order to suppress the increment of the viscosity of the liquid, it has been proposed to cause minute liquid circulation (microcirculation) in individual channels including the ejection port and to cause larger scale liquid circulation (macrocirculation) in a common channel communicating with the individual channels. International Publication No. WO2018/208276 discloses a liquid ejection head in which a microcirculation region is provided on one side of a substrate and a macrocirculation region is provided on the other side of the substrate, and these regions are communicated by a through hole provided in the substrate. International Publication No. WO2019/078868 discloses a liquid ejection head in which an individual channel performing microcirculation is arranged close to a common channel performing macrocirculation.
In the liquid ejection head described in International Publication No. WO2018/208276, the microcirculation region and the macrocirculation region are separated. Therefore, it is easy for the concentrated ink that has flowed out from the individual channels to reflow from the individual channels by the microcirculation. In the liquid ejection head described in International Publication No. WO2019/078868, the concentrated ink that has flowed out from the individual channels accumulates on a downstream portion by macro-circulation flow. However, when the ink is ejected from the ejection port, the ink is supplied from the inlet and outlet of the individual channels, so the concentrated ink is also supplied from the outlet to the individual channels. Therefore, these liquid ejection heads may not be able to suppress the increment of the viscosity of the ink near the ejection port.
It would be beneficial to overcome these deficiencies and suppress the increment of the viscosity of the ink near the injection port.
The present disclosure advantageously provides a liquid ejection head that has an individual channel communicating with an ejection port, in which the liquid circulates in the individual channel and the reflow of the liquid that has flowed out from the individual channel into the individual channel can be suppressed.
According to some embodiments, a liquid ejection head includes a substrate having a first surface and a second surface which is a back surface of the first surface, a plurality of individual circulation channels provided on the first surface of the substrate, each of the plurality of individual circulation channels communicating with an ejection port of a liquid and recirculating the liquid, and a common circulation channel communicating with the plurality of individual circulation channels and recirculating the liquid. The common circulation channel includes a connection area provided on the first surface of the substrate and communicating with outlets of the plurality of individual circulation channels, a supply port which penetrates the substrate and supplies the liquid to the connection area, and a correct port which penetrates the substrate and corrects the liquid from the connection areas.
Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Various exemplary embodiments, features, and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings.
One of the purposes of this disclosure is to provide a liquid ejection head that has an individual channel communicating with an ejection port, in which the liquid circulates in the individual channel and the reflow of the liquid that has flowed out from the individual channel into the individual channel can be suppressed.
By referring to the drawings, some embodiments of a liquid ejection head of the present disclosure are described below. Since the embodiments described below are suitable embodiments of the present disclosure, various technically favorable limitations are applied. However, it goes without saying that the present disclosure is not limited to these embodiments. The liquid ejection head, which is one aspect of the present disclosure, is applicable to devices such as printers, copiers, facsimiles with communication systems, word processors with printer parts, and industrial recording devices combined with various processing devices in a complex manner. While the following embodiments are intended for ink ejection heads that eject the ink, the present disclosure can also be used for applications that eject liquids other than ink, such as biochip fabrication and electronic circuit printing.
In the following description and drawings, a first surface 1a of a substrate 1 is a surface on which an individual channel 4 and an ejection port 5 are formed, and a second surface 1b of the substrate 1 is a back surface of the first surface 1a. A first direction X is parallel to the first surface 1a and the second surface 1b of the substrate 1, and is a direction in which a channel row 31, an ejection port row 32, and through-hole rows 33-35 described below extend. The first direction X corresponds to a longitudinal direction of a liquid ejection head 100. A second direction Y is parallel to the first surface 1a and the second surface 1b of the substrate 1 and is perpendicular to the first direction X. The second direction Y corresponds to the short-side direction of the liquid ejection head 100. A Z direction is perpendicular to the first surface 1a and the second surface 1b of the substrate 1, that is, perpendicular to the first direction X and the second direction Y.
The individual channel 4 is a circulation channel provided on the first surface 1a of the substrate 1 for the ink recirculation. The individual channel 4 has an approximately U-shape, and the recirculation element 7 is provided on an upstream side and an energy generating element 6 is provided on a downstream side. A partition 16 is provided between the energy generating element 6 and the recirculation element 7. The plurality of individual channels 4 form the channel row 31 extending in the first direction X, and in accordance with such arrangement, the ejection ports 5 form the ejection port row 32 extending in the first direction X. In
When the energy generating element 6 is not driven (when the ink is not ejected), the ink entering the individual channel 4 from the connection area 8 through the inlet 41 is driven by the recirculation element 7, passes through the energy generating element 6, and flows out from the outlet 42 to the connection area 8. Such flow of the ink generates a microcirculation C1 in the individual channel 4. The microcirculation C1 is the micro-circulation of the ink in a unit of the individual channel 4 caused by the recirculation elements 7. That is, the microcirculation C1 occurs respectively in the individual channel 4 including one ejection port 5, one energy generating element 6, and one recirculation element 7. When the ink is not ejected, the concentrated ink of which viscosity increases by the evaporation from the ejection port 5 flows out from the outlet 42 of the individual channel 4 by the microcirculation C1. Thus, the concentrated ink in the vicinity of the ejection port 5 is replaced with fresh ink, and clogging of the ejection port 5 can be suppressed.
Supply through-holes (supply ports) 9 each penetrating the substrate 1 and correct through-holes (correct ports) 10 each penetrating the substrate 1 are formed in the substrate 1. Supply through-holes 9 and correct through-holes 10 penetrate the substrate 1 from the first surface 1a to the second surface 1b. Seen from the Z direction, supply through-holes 9 and correct through-holes 10 are located in the connection area 8. The channel member 3 is provided with a supply channel 11 and a correct channel 12 both facing the second surface 1b of the substrate 1. The supply channel 11 is connected to the supply through-hole 9 and the correct channel 12 is connected to the correct through-hole 10. Seen from the Z direction, the supply channel 11 and the correct channel 12 are separated from each other by a partition 13 provided between the supply through-hole 9 and the correct through-hole 10. Although the partition 13 extends linearly in the first direction X, its shape is not limited if the supply channel 11 and the correct channel 12 can be separated. With the above described configuration, the connection area 8, the supply through-hole 9, the correct through-hole 10, the supply channel 11, and the correct channel 12 form the ink circulating channel 8-12. The ink flows into the first surface 1a side of the substrate 1 through the supply channel 11 and the supply through-hole 9, and then flows through the connection area 8 on the first surface 1a side, to the correct through-hole 10, and then flows to the correct channel 12 in this order. The supply through-hole 9 supplies the ink to the connection area 8, and then supplies the ink to each of the plurality of individual channels 4 through the connection area 8. The correct through-hole 10 corrects the ink from the connection area 8. That is, the correct through-hole 10 corrects the ink from each of the plurality of individual channels 4 through the connection area 8.
As described above, the circulation channel 8-12 is a channel in which the ink recirculates in communication with each of the plurality of individual channels 4. The ink circulation occurring in the circulation channel 8-12 is called a macrocirculation C2. The macrocirculation C2 has a range of circulation larger than that of the microcirculation C1. As described later, the macrocirculation C2 is not needed to supply the ink to individual channels 4, but is configured to recirculate ink flowing out from each of the plurality of individual channels 4. The macrocirculation C2 is generated by a recirculation element used for macrocirculation provided in the circulation channel 8-12, a circulation pump (both not shown) provided outside the substrate 1, and the like.
The plurality of supply through-holes 9 and the plurality of correct through-holes 10 are provided in the first direction X, respectively, to form a supply through-hole row 33 and a correct through-hole row 34. In
Comparative examples are described here with reference to
One of the causes of the above problems in the comparative example is that the individual channel 4 performing the microcirculation C1 and the circulation channel performing the macrocirculation C2 communicate only through the through-hole 109 of the substrate 1. Since the microcirculation C1 occurs only on a first surface 1a side of a substrate 1 and the macrocirculation C2 occurs only on a second surface 1b side of the substrate 1, the effect of replacing the concentrated ink in the individual channel 4 with fresh ink by the macrocirculation C2 is limited. Therefore, the concentrated ink flowing out from the outlet 42 of the individual channel 4 cannot be efficiently discharged from the connection area 8. On the other hand, in the first embodiment, since the supply channel 11 and the correct channel 12 are separated from each other by the partition 13, the macrocirculation C2 flows through the supply through-hole 9 to the connection area 8 on the first surface 1a side of the substrate 1, i.e., flows in the vicinity of the outlet 42 of the individual channel 4. In other words, the macrocirculation C2 flows at the same level as the microcirculation C1 in the Z direction. Concentrated ink that has flowed from the individual channel 4 to the connection area 8 by the microcirculation C1 is efficiently discharged from the connection area 8 by the macrocirculation C2, and the ink in the individual channel 4 is replaced with fresh ink. Since the concentrated ink is hard to stay in the connection area 8, the possibility of the concentrated ink flowing back from the connection area 8 to the individual channel 4 during ink ejection is also reduced. This reduces the influence of the concentrated ink flowing out from the outlet 42 of the individual channel 4. Note that although the recirculation element 7 is used as an electrothermal conversion element in the present embodiment, when a piezo element is used, the inlet 41 and outlet 42 of the individual channel 4 may be reversed from the present embodiment depending on the driving method. In this case, the same configuration as in the present embodiment can be applied.
The supply through-hole 9 and the correct through-hole 10 cooperate to form a through-holes row 35 extending in the first direction X. The supply through-hole 9 and the correct through-hole 10 are alternately arranged in the first direction X, and the macrocirculation C2 is formed between the supply through-hole 9 and the correct through-hole 10 in the first direction X. The channel row 31 is provided on both sides of the through-holes row 35 in the second direction Y. That is, one of through-hole rows 35 is combined with two of channel rows 31. The circulation channel 8-12 has a connection area 8, the supply through-hole 9, the correct through-hole 10, a supply channel 11, and a correct channel 12.
The supply through-hole 9 and the correct channel 12 face the second surface 1b of the substrate 1 and communicate with the supply channel 11 and the correct through-hole 10, respectively. A partition 13 separating the supply channel 11 and the correct channel 12 extends in a meandering manner along the periphery of the supply through-hole 9 and the correct through-hole 10 when viewed from the Z direction. The supply through-hole 9 is connected to the supply channel 11 by a supply connection channel 14 branching in a comb-toothed manner from the supply channel 11 and extending in the second direction Y. Similarly, the correct through-hole 10 is connected to the correct channel 12 by a correct connection channel 15 branching in a comb-toothed form from the correct channel 12 and extending in the second direction Y.
In the first embodiment, the macrocirculation C2 flows along the second direction Y mainly between the supply through-hole row 33 and the correct through-hole row 34 in the connection area 8. In contrast, in the present embodiment, the macrocirculation C2 flows long the first direction X in the connection area 8, and the ink flow becomes dominant especially in the region along the through-hole row 35. Therefore, the macrocirculation C2 can flow in a region close to the outlet 42 of the individual channel 4. Since the supply through-hole 9 and the correct through-hole 10 are alternately arranged, the macrocirculation C2 flows more uniformly along the second direction Y. For these reasons, the concentrated ink flowing out from the outlet 42 of the individual channel 4 can be discharged more efficiently from the connection area 8. In addition, the supply through-hole 9 and the correct through-hole 10 are alternately arranged in this embodiment, so that only one through-hole row 35 is needed. Therefore, a space between the through-holes and a space between through-hole rows are reduced as compared with the first embodiment, and the size of the second direction Y of the liquid ejection head 100 can be reduced.
A supply connection channel 14 branches from a supply channel 11 in a comb-toothed manner and extends in the second direction Y. The supply connection channel 14 is connected to each of the supply through-holes 9 in the same position in the first direction X of a plurality of (in this embodiment, two) through-hole rows 35. Similarly, a correct connection channel 15 branches from a correct channel 12 in a comb-toothed manner and extends in the second direction Y The correct connection channel 15 is connected to each of the correct through-holes 10 in the same position in the first direction X of the plurality of (in this embodiment, two) through-hole rows 35. The number of through-hole rows 35 is not limited to two, and three or more through-hole rows 35 may be provided. Since the plurality of through-hole rows 35 can be provided between one supply channel 11 and one correct channel 12, the number of ejection port rows 32 combined with corresponding through-hole rows 35 can also be increased. Therefore, many ejection ports 5 can be provided while suppressing the size in the second direction Y of the liquid ejection head 100.
An inlet 41 of an individual channel 4 is connected to another connection area 8a, which is different from a connection area 8. Through-hole rows 35 and 36 combined with the individual channel 4 are provided on both sides of the individual channel 4. The through-hole row 35 is located in the connection area 8, and the through-hole row 36 is located in another connection area 8a. Only a supply through-hole 9 is provided in another connection area 8a, and the correct through-hole 10 is not provided.
That is, the through-hole row 36 is composed of only the supply through-hole 9, and another connection area 8a is connected to a supply channel 17 where ink is not recirculated. The supply channel 17 and a supply channel 11 are separated from each other by a partition 18. A microcirculation C1 is different from the first to third embodiment in that it flows between different connection areas 8 and 8a.
The configuration of the connection area 8 is similar to that of the second embodiment. The supply through-hole 9 and a correct through-hole 10 are alternately arranged in the first direction X to form the through-holes row 35 extending in the first direction X. A macrocirculation C2 flows in the first direction X between the supply through-hole 9 and the correct through-hole 10 in the connection area 8. The supply through-hole 9 is connected to the supply channel 11 by a supply connection channel 14 branching in a comb-toothed manner from the supply channel 11 and extending in the second direction Y. Similarly, the correct through-hole 10 is connected to a correct channel 12 by a correct connection channel 15 branching in a comb-toothed manner from the correct channel 12 and extending in the second direction Y.
When the inlet 41 and the outlet 42 of the individual channel 4 are respectively connected to different connection areas 8 and 8a, a sufficient effect can be obtained by performing the macrocirculation C2 only in the connection area 8 connecting to the outlet 42.
Therefore, according to this embodiment, the rationalization of the pump for the macrocirculation C2 is possible. However, it is preferable that the pressure at the inlet 41 is set higher than that at the outlet 42 in order to prevent the concentrated ink from entering the individual channel 4 from the connection area 8. This can be achieved by controlling the pressure of the pump that is used for supplying the ink to the supply channel 17. Since each individual channel 4 extends linearly in the second direction Y, it has excellent placement efficiency. However, as long as the inlet 41 and the outlet 42 are respectively connected to different connection areas 8 and 8a, the shape of the individual channel 4 is not limited in any way and may be cured shape or broken shape. In this embodiment, the ejection port 5 can be arranged linearly in the first direction X.
However, it is also possible to arrange the outlets 5a and 5b in the first direction X as located on separate rows by shifting the outlets 5a and 5b of different sizes in the second direction Y as shown in
As in the third embodiment, a supply connection channel 14 branches from a supply channel 11 in a comb-toothed manner and extends in the second direction Y. The supply connection channel 14 is connected to each of the supply through-holes 9 in the same position in the first direction X of the plurality of (in this embodiment, three) through-hole rows 35. Similarly, a correct connection channel 15 branches from a correct channel 12 in a comb-toothed manner and extends in the second direction Y The correct connection channel 15 is connected to each of the correct through-holes 10 in the same position in the first direction X of the plurality of (in this embodiment, three) through-hole rows 35. The number of through-hole rows 35 is not limited to three.
Since the plurality of through-hole rows 35 can be provided between one supply channel 11 and one correct channel 12 in this embodiment as in the third embodiment, the number of ejection port rows 32 combined with this can also be increased. Therefore, many ejection ports 5 can be provided while suppressing the size of the second direction Y of the liquid ejection head 100.
While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure 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 priority from Japanese Patent Application No. 2022-039335, filed Mar. 14, 2022, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
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2022-039335 | Mar 2022 | JP | national |