The present invention relates to a liquid ejection head and a liquid ejection apparatus.
An ejection head included by an inkjet recording apparatus includes, for example, pressure chambers, piezoelectric elements that contract the pressure chambers, and a plate in which a plurality of ejection orifices are formed, and ejects ink in the pressure chambers as liquid droplets from predetermined ejection orifices by changing capacities of the pressure chambers by the piezoelectric elements. Some of the plurality of ejection orifices sometimes do not eject ink at a time of ejection operation. Ink in the ejection orifices that do not eject ink increases in viscosity because volatile components evaporate from the surface of the ink. As a result, the ejection head sometimes causes ejection failure.
To suppress the ejection failure, there is a circulation mechanism that connects the pressure chambers to a circulation channel to circulate ink in a vicinity of the ejection orifices, for example. The ejection head that adopts the circulation mechanism includes a supply flow path and a recovery flow path of ink, which configure a part of the circulation channel, in the ejection head. In order to make the ejection head adopting the mechanism compatible with high image quality, it is necessary to dispose a plurality of ejection orifices with high density. In this case, the same number of pressure chambers and piezoelectric elements of the ejection head as the number of discharge orifices are required.
The ejection head compatible with high image quality adopting the circulation mechanism has a large number of pressure chambers in addition to the supply flow path and the recovery flow path for performing circulation, so that efficient disposition of these components becomes a problem. For example, in the case of the ejection head disclosed in Japanese Patent Application Laid-Open No. 2014-65313, the pressure chambers cannot be disposed in a region where individual wirings are disposed on a surface where the piezoelectric elements are disposed, so that a plurality of ejection orifices cannot be disposed with high density.
The present invention has an object to provide a liquid ejection head in which a plurality of ejection orifices that eject liquid can be disposed with high density, in a liquid ejection head in which supply and recovery of liquid are performed.
A liquid ejection head of the present invention includes a first pressure chamber row having a plurality of first pressure chambers respectively communicating with a plurality of ejection orifices that eject liquid and arranged along a predetermined direction, a second pressure chamber row having a plurality of second pressure chambers respectively communicating with a plurality of ejection orifices that eject liquid and arranged along the predetermined direction, a first flow path for supplying the liquid to the plurality of first pressure chambers, and a second flow path for recovering the liquid from the plurality of second pressure chambers, wherein part of the first pressure chamber row is disposed to overlap the first flow path, and part of the second pressure chamber row is disposed to overlap the second flow path, as viewed from an ejection direction of the liquid.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Preferred embodiments of the present invention will now be described in detail in accordance with the accompanying drawings.
Hereinafter, a first embodiment and a modified example of the first embodiment will be described.
As illustrated in
Individual wirings 113 connected to the individual piezoelectric elements 112 are led out to the other end side in the short-side direction of the head chip 100, that is, a side where the recovery hole 117 is formed to be connected to the driving IC 114. To the driving IC 114, a FPC 115 that transmits a signal for driving the piezoelectric elements 112 to eject ink is connected.
The ink to be ejected from the respective ejection orifices 102 is supplied to the common supply flow path 104 from the supply hole 116 connected to an outside, and further passes through the respective supply branch flow paths 105 from the common supply flow path 104 to be supplied to the respective pressure chambers 110.
An ejection control signal from a control section (not illustrated) included by the liquid ejection apparatus 10 is transmitted to the driving IC 114 via the FPC 115, and a voltage waveform for ejection driving which is outputted from the driving IC 114 is applied to the respective piezoelectric elements 112 through the respective individual wirings 113. As a result, the respective pressure chambers 110 are expanded and contracted by the respective piezoelectric elements 112, that is, capacities of the respective pressure chambers 110 are changed, whereby the ink is ejected from the respective ejection orifices 102. In relation to this, of the ink that is supplied to the respective pressure chambers 110, the ink that is not ejected passes through the common recovery flow path 106 via the recovery branch flow path 107 and is discharged to an outside of the head chip 100 from the recovery hole 117 to be recovered. The outside is a circulation channel (not illustrated) as an example, and to the circulation channel, an ink tank (not illustrated) that houses the ink to be supplied to the head chip 100 is connected. That is, the head chip 100 of the present embodiment is connected to the circulation channel to which the ink tank is connected, so that the ink flows from the outside via the supply hole 116, and the ink flows to the outside via the recovery hole 117.
A steady flow of the ink like this is effective for preventing ejection failure of the liquid ejection head 20 caused by increase in viscosity of the ink that occurs after a volatile component of the ink evaporates from an ink surface in the ejection orifices 102 in a period in which the predetermined ejection orifices 102 do not eject ink. A configuration may be adopted, in which the direction in which the ink flows in the steady flow is made such that the recovery hole 117 with a small opening area is made the supply hole, and the supply hole 116 with a large opening area is made the recovery hole, that is, the direction in which the ink flows is made an opposite direction. For example, when the ink is ejected continuously from the large number of ejection orifices 102 in addition to the steady flow, a large amount of ink needs to be supplied. In this case, a configuration may be adopted, in which the ink can be supplied by being passed inversely from the supply hole 116 that is used as the recovery hole with the large opening area and small flow resistance.
As illustrated in
The ink passes through a supply connection flow path 201 from the supply branch flow path 105, thereafter further passes through a supply through hole 202, and is supplied to the pressure chamber 110. A supply connection flow path 201 and a supply through hole 202 are used as throttle flow path. The supply through hole 202 is formed to penetrate through the flow path forming layer 103 in a thickness direction of the flow path forming layer 103. The supply connection flow path 201 and the supply through hole 202 are configured so that pressure in the pressure chamber 110 at a time of the pressure chamber 110 being contracted at the time of ink ejection does not escape to a supply flow path side (supply branch flow path 105 side). More specifically, in the supply connection flow path 201 and the supply through hole 202, flow path sectional areas are set to be smaller than a flow path sectional area of the pressure chamber 110 in order to increase the flow resistance, and lengths are formed to be long to increase inertance, respectively.
A feedthrough 203 is formed at a side opposite to the supply through hole 202 with the supply branch flow path 105 sandwiched between the feed through 203 and the supply through hole 202, that is, at a side opposite to the ink supply side of the pressure chamber 110. The feedthrough 203 communicates with the pressure chamber 110, penetrates through the flow path forming layer 103 to the orifice plate 101 side from the pressure chamber 110 side, and communicates with the ejection orifice 102.
In a portion at an undersurface side (orifice plate 101 side) in the flow path forming layer 103, a throttle flow path 204 that causes the feedthrough 203 and the recovery branch flow path 107 to communicate with each other is formed. The throttle flow path 204 is configured so that the pressure in the pressure chamber 110 at the time of the pressure chamber 110 being contracted at the time of ink ejection does not escape to the supply flow path side (supply branch flow path 105 side) like the supply connection flow path 201 and the supply through hole 202. That is, in the throttle flow path 204, a flow path sectional area thereof is set to be smaller than the flow path sectional area of the pressure chamber 110 (the flow resistance is set to be larger than the pressure chamber 110), and a length is formed to be long to increase inertance.
A joining portion with the flow path forming layer 103 in the actuator layer 111 is a vibration plate 205 made of SiN or the like. In the present embodiment, the vibration plate 205 forms parts of walls of the respective pressure chambers 110. A plurality of individual wirings 113 that are connected to the respective piezoelectric elements 112 are disposed on an upper side of the vibration plate 205. An insulation layer 206 made from SiO2 or the like is formed on the vibration plate 205 and the plurality of individual wirings 113. On the insulation layer 206, a common electrode 207 that is connected to one surfaces of the plurality of piezoelectric elements 112 and is used as a common electrode of the plurality of piezoelectric elements 112 is formed.
On an upper side of the common electrode 207, the piezoelectric elements 112 are disposed correspondingly to the respective pressure chambers 110. On the respective piezoelectric chambers 112, individual electrodes 208 are formed. The respective individual electrodes 208 are covered with an insulation layer 209.
One hole is opened in each of the insulation layer 209 on the individual electrode 208, and a layered body composed of the insulation layer 206 on the individual wirings 113, the common electrode 207 and the insulation layer 209. The hole in the layered body is a through hole 211. The individual electrode 208 and the individual wiring 113 are connected by the connection electrode 210. The common electrode 207 and the individual wiring 113 are led out to the end portion (the other end side) in the short-side direction of the head chip 100 and are respectively connected to the driving IC 114. (refer to
As illustrated in
As above, part of the first pressure chamber row 110A is disposed to overlap the first flow path, and part of the second pressure chamber row 110B is disposed to overlap the second flow path, viewed from the ink ejection direction. That is, in the case of the present embodiment the supply branch flow path 105 and the recovery branch flow path 107 are overlapped with the pressure chambers 110 in the ink ejection direction. Consequently, according to the present embodiment, in the liquid ejection head 20 in which supply and recovery of the ink are performed, a plurality of ejection orifices 102 can be disposed with high density.
Further, in the present embodiment, a plurality of individual wirings 113 are disposed to overlap the pressure chambers 110 as viewed from the ink ejection direction. More specifically, the plurality of individual wirings 113 are disposed to overlap the respective piezoelectric elements 112. Consequently, according to the present embodiment, in the liquid ejection head 20 in which supply and recovery of the ink are performed, the plurality of ejection orifices 102 can be disposed with high density.
Next, concerning a second embodiment, a different part from the aforementioned first embodiment will be described with reference to
In the first embodiment, the flow path forming layer 103 is formed so that the pressure chambers 110 forming the single rows, that is, the first pressure chamber row 110A and the second pressure chamber row 110B overlap each of the supply branch flow paths 105 and each of the recovery branch flow paths 107 (
As illustrated in
In the present embodiment, a flow resistance of a flow path from the supply branch flow path 105 to the recovery branch flow path 107 through the first pressure chamber, and a flow resistance of a flow path from the supply branch flow path 105 to the recovery branch flow path 107 through the second pressure chamber are set to be substantially equal (substantially the same). Accordingly, in the present embodiment, an ejection characteristic of the ink that is ejected via the respective first pressure chambers of the first pressure chamber row 110A, and an ejection characteristic of the ink that is ejected via the respective second pressure chambers of the second pressure chamber row 110B are substantially made equal easily. Further, the present embodiment can reduce the flow resistance of the branch flow paths as the widths of the respective supply branch flow paths 105 and the respective recovery branch flow paths 107 can be made wider, as compared with the first embodiment. Further, the present embodiment is capable of setting the supply connection flow path 212 to be longer as compared with the first embodiment, and therefore can make it difficult for the pressure occurring in the pressure chambers 110 at the time of ink ejection to escape to the ink supply side.
Next, concerning a third embodiment, a part different from the first embodiment and the second embodiment mentioned above will be described with reference to
The present embodiment is configured to supply and eject different kinds of inks (two kinds of inks as an example). More specifically, a head chip 100B of the present embodiment is configured such that two head chips 100 in the first embodiment are aligned in a state where mutual one end sides (supply hole 116 sides) in the short-side direction are adjacent to each other, and integrally formed (refer to
According to the above configuration, the present embodiment can supply and eject two kinds of inks, for example, inks of different colors, with one head chip 100B.
As above, the first to third embodiments are described as examples, but the mode included in the technical range of the present disclosure is not limited to the first to the third embodiments.
For example, the head chip 100B of the third embodiment is described as the configuration equivalent to the combination of the two head chips 100 of the first embodiment. However, as a modified example of the third embodiment, a combination of two of the head chips 100A of the second embodiment may be adopted, for example. Further, as another modified example of the third embodiment, a configuration equivalent to a combination of two head chips composed of the head chip 100 of the first embodiment and the head chip 100A of the second embodiment may be adopted, for example.
Each of the embodiments is described such that deformation of the respective pressure chambers 110 is performed by the piezoelectric elements 112 such as PZT. However, a heater (not illustrated) may be used, in place of the piezoelectric elements 112 and the vibration plate 205.
In the second embodiment, the flow resistance of the flow path from the supply branch flow path 105 to the first pressure chamber and the flow path from the first pressure chamber to the recovery branch flow path 107, and the flow resistance of the flow path from the supply branch flow path 105 to the second pressure chamber and the flow path from the second pressure chamber to the recovery branch flow path 107 are set as substantially equal. In the first embodiment and the third embodiment, the above described setting of the second embodiment may be adopted.
According to the liquid ejection head of the present disclosure, in the liquid ejection head in which supply and recovery of the liquid are performed, the plurality of ejection orifices that eject a liquid can be disposed with high density.
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. 2018-045169, filed Mar. 13, 2018 which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
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2018-045169 | Mar 2018 | JP | national |