JP2017121794A - Liquid discharge device and control method for liquid discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid discharge device comprising a common supply channel and a common recovery channel to circulate ink within a recording element substrate, which can fill and recover the liquid with the remaining of air bubbles suppressed within the liquid discharge head.SOLUTION: A common supply channel 211 and a common recovery channel 212 are filled with a liquid by driving pressurizing means 1004 while the common supply channel 211 and the common recovery channel 212 are placed in a communicating state. The liquid filled to the common supply channel 211 and to the common recovery channel 212 is then pressurized by the pressurizing means 1004 while the common supply channel 211 and the common recovery channel 212 are being blocked by switching means 237. The liquid is thus filled to the supply channel 213 in communication with the recording element substrate 10 and common supply channel 211, to the recovery channel 214 in communication with the recording element substrate 10 and the common recovery channel 212, and to a discharge port 13.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a liquid ejecting apparatus including a recording element substrate having an ejection port capable of ejecting ink, and a control method for the liquid ejecting apparatus.

  In a liquid discharge apparatus such as an ink jet recording apparatus, it is necessary to stably supply ink from an ink tank in which ink is stored to a liquid discharge head. One factor that hinders the stable supply of ink is the mixing of bubbles into the flow path of the liquid ejection head. If bubbles exist in the flow path of the liquid discharge head, ink is not properly supplied to the discharge port due to pressure loss due to the bubbles, and ink discharge becomes unstable, leading to deterioration in ink landing accuracy. Further, when the vicinity of the pressure chamber is filled with bubbles due to bubble growth due to a rapid change in temperature or the like, the supply of ink to the pressure chamber is hindered and ink is not ejected.

  It is known to perform a filling operation and a recovery operation in order to remove such bubbles that adversely affect the discharge from the flow path in the liquid discharge head. The filling operation refers to filling ink into a liquid ejection head that is not filled with ink, and the recovery operation refers to a case where ink is filled in a part or all of the flow path in the liquid ejection head. When bubbles are present in the inside, it refers to removing the bubbles so that they can be discharged. The recovery operation is also effective in eliminating ink concentration caused by water evaporation from the ejection port.

  Patent Document 1 discloses an ink jet recording apparatus that can perform filling and recovery operations on a liquid discharge head. The ink jet recording apparatus includes a supply pump that supplies ink, an ink circulation channel that supplies and discharges ink to and from the liquid discharge head, and a valve that is disposed in the ink circulation channel. When ink is filled, bubbles in the flow path can be discharged together with ink from the discharge port by closing the valve and pressurizing the supply pump.

JP 2005-53048 A

  Currently, in order to circulate the ink in the discharge port of the liquid discharge head, a liquid discharge head having a common supply channel for supplying ink to the recording element substrate and a common recovery channel for recovering ink from the recording element substrate has been proposed. ing. When the filling / recovery operation used in Patent Document 1 is performed on this liquid discharge head, bubbles present in the flow path between the supply pump and the liquid discharge head can be discharged from the discharge port. There is a problem that bubbles remaining on the downstream side of the substrate cannot be sufficiently removed. In this case, if the operation of circulating the ink is performed, bubbles remaining in the supply flow channel flow into fine flow channels and ejection openings formed in the recording element substrate, which causes a decrease in recording quality.

  The present invention can perform filling and recovery while suppressing residual bubbles in the liquid ejection head in a liquid ejection apparatus having a common supply channel and a common recovery channel to circulate ink in the recording element substrate. An object of the present invention is to provide a liquid ejecting apparatus and a control method thereof.

  According to a first aspect of the present invention, there is provided a recording element substrate having a discharge port for discharging a liquid, a supply channel for supplying liquid to the recording element substrate, a recovery channel for recovering liquid from the recording element substrate, and the supply A common supply channel for supplying liquid to the channel, a common recovery channel for recovering liquid from the recovery channel, and a pressurizing means for applying pressure to the common supply channel and the common recovery channel Switching means for switching communication and blocking of the common supply flow path and the common recovery flow path, and control means for controlling the pressurizing means, the control means comprising the common supply flow path and the common recovery flow path By driving the pressurizing means in a state where the flow paths are in communication, the common supply flow path and the common recovery flow path are filled with liquid, and the common supply flow path and the common recovery flow path are switched. In the state of being blocked by means. Liquid that fills the supply flow path, the discharge port, and the recovery flow path by pressurizing the liquid filled in the supply flow path and the common recovery flow path with the pressurizing unit. It is a discharge device.

  According to a second aspect of the present invention, there is provided a recording element substrate having a discharge port for discharging a liquid, a supply channel for supplying the liquid to the recording element substrate, a recovery channel for recovering the liquid from the recording element substrate, A common supply channel for supplying liquid to the supply channel, a common recovery channel for recovering liquid from the recovery channel, and a pressure applied to the common supply channel and the common recovery channel. A liquid ejection apparatus control method comprising: a pressure unit; and a switching unit that switches between communication and blocking of the common supply channel and the common recovery channel, wherein the common supply channel and the common recovery channel are in communication with each other. The step of filling the common supply flow path and the common recovery flow path by driving the pressurizing means in the state of being made to shut off the common supply flow path and the common recovery flow path by the switching means The common supply flow path in the state And the step of filling the supply channel, the discharge port, and the recovery channel with liquid by pressurizing the liquid charged in the common recovery channel with the pressurizing means. Control method for liquid ejection device.

  According to the present invention, in a liquid ejection apparatus having a common supply channel and a common recovery channel for circulating ink in a recording element substrate, filling and recovery are performed while suppressing residual bubbles in the liquid ejection head. Is possible.

It is a side view showing a schematic structure of a liquid ejection device in an embodiment of the present invention. It is a perspective view of a droplet discharge head in an embodiment of the present invention. It is sectional drawing which shows the structural example of the liquid discharge head in the embodiment body of this invention. FIG. 3 is an explanatory diagram illustrating a liquid discharge head and a peripheral portion in the first embodiment. It is a flowchart of the filling / recovery operation in the first embodiment. It is explanatory drawing which shows the filling / recovery operation | movement in 1st Embodiment. FIG. 6 is an explanatory diagram illustrating a state where one recording element substrate is provided in the liquid ejection apparatus. It is a flowchart of the filling / recovery operation in the first embodiment. It is explanatory drawing which shows the filling / recovery operation | movement in 1st Embodiment. It is explanatory drawing which shows the liquid discharge head and peripheral part in 2nd Embodiment. It is a vertical side view which shows the internal structure of an upstream pressure control mechanism. It is a flowchart of the filling / recovery operation in the second embodiment. It is explanatory drawing of the liquid discharge head and peripheral part in 2nd Embodiment. FIG. 6 is an explanatory diagram illustrating a state where one recording element substrate is provided in the liquid ejection apparatus. It is explanatory drawing of the other example of the liquid discharge head and peripheral part in 2nd Embodiment. It is a flowchart which shows operation | movement of the 1st modification in 2nd Embodiment. It is explanatory drawing which shows the filling and the recovery | restoration operation | movement in the 1st modification of 2nd Embodiment. It is a flowchart which shows operation | movement of the 2nd modification in 2nd Embodiment. It is explanatory drawing which shows the filling and the recovery | restoration operation | movement in the 2nd modification of 2nd Embodiment. It is explanatory drawing of the supply / recovery flow path of the ink in 3rd Embodiment. It is a vertical side view which shows the internal structure of a downstream pressure adjustment mechanism. It is a flowchart which shows the filling / recovery operation | movement in 3rd Embodiment. It is explanatory drawing which shows the filling and recovery operation | movement in 3rd Embodiment. FIG. 6 is a schematic diagram of a printable state of a droplet discharge head according to a third embodiment. FIG. 6 is an explanatory diagram illustrating a state where one recording element substrate is provided in the liquid ejection apparatus. It is explanatory drawing of the other example of the liquid discharge head and peripheral part in 3rd Embodiment. It is a flowchart which shows the filling and the recovery | restoration operation | movement in the 1st modification of 3rd Embodiment. It is explanatory drawing which shows the filling and the recovery | restoration operation | movement in the 1st modification of 3rd Embodiment. It is a flowchart which shows the filling and the recovery | restoration operation | movement in the 2nd modification in 3rd Embodiment. It is explanatory drawing which shows the flow of the ink at the time of the filling and recovery operation | movement in a 2nd modification. It is a side view which shows schematic structure of the liquid discharge apparatus in 4th Embodiment. It is a perspective view which shows schematic structure of a liquid discharge apparatus. It is a schematic diagram which shows the 1st circulation form of the circulation path applied to the recording device of this embodiment. It is a schematic diagram which shows the 2nd circulation form of the circulation path applied to the recording device of this embodiment. FIG. 6 is a schematic diagram illustrating a difference in the amount of ink flowing into the liquid ejection head 3 between a first circulation mode and a second circulation mode. It is a perspective view which shows schematic structure of a liquid discharge head. FIG. 6 is an exploded perspective view showing each component or unit constituting the liquid discharge head. It is the figure which showed the surface and the back surface of the 1st-3rd flow path member. It is a perspective view which expands and shows the (alpha) part of Fig.37 (a). It is the figure which showed the cross section in the IX-IX line of FIG. It is the schematic diagram which showed the discharge module. It is the schematic diagram which showed the recording element board | substrate. It is a perspective view which shows the cross section of the recording element board | substrate and cover plate in the XII-XII line | wire in Fig.41 (a). FIG. 6 is a plan view showing a partially enlarged adjacent portion of a recording element substrate in two adjacent ejection modules. It is the perspective view which showed the liquid discharge head in 6th Embodiment. FIG. 45 is an exploded perspective view of the liquid discharge head shown in FIG. 44. It is a figure which shows a 1st, 2nd flow path member. FIG. 5 is a perspective view showing a connection relationship between a recording element substrate and a liquid in a flow path member. It is the figure which showed the cross section in the XVIII-XVIII line | wire of FIG. It is the perspective view which showed one discharge module, and its exploded view. FIG. 3 is a schematic diagram illustrating a recording element substrate and a cover plate. It is the schematic diagram which showed the inkjet recording device in 6th Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a side view showing a schematic configuration of a liquid ejection apparatus according to an embodiment of the present invention. The liquid ejecting apparatus shown here constitutes an ink jet recording apparatus (hereinafter also referred to as a recording apparatus) 1000 that performs recording by ejecting ink. The recording apparatus according to the embodiment can be applied to an apparatus such as a printer, a copier, a facsimile having a communication system, a word processor having a printer unit, or an industrial recording apparatus combined with various processing apparatuses. For example, it can be used for applications such as biochip fabrication and electrical circuit printing.

The recording apparatus 1000 includes a conveyance unit 1 that conveys the recording medium 2, a line-type liquid ejection head 3 that is disposed substantially orthogonal to the conveyance direction of the recording medium 2, and supplies liquid such as ink to the liquid ejection head 3. Liquid supply means, a controller (control means) 3000, and the like.
As the recording medium 2, cut paper, a continuous roll medium, or the like can be used. The recording apparatus in the present embodiment is a line type recording apparatus that performs recording in one pass while conveying the recording medium 2 continuously or intermittently. The liquid ejection head 3 includes a plurality of recording element substrates 10 in which a plurality of ejection openings are arranged along a direction (orthogonal direction in FIG. 1) that intersects the conveyance direction of the recording medium. As a whole, a long discharge port array is formed. Each ejection port is provided with a recording element that generates ejection energy for ejecting liquid such as ink, and by driving the recording element, the ink filled in the ejection port is directed to the recording medium 2 in a droplet state. To discharge. In this embodiment, ejection port arrays for ejecting cyan C, magenta M, yellow Y, and black K inks are formed in each recording element substrate 10, and ink is ejected from these ejection port arrays. As a result, full color recording can be performed.

  Further, the recording apparatus 1000 takes a form in which a liquid such as ink is circulated between the liquid supply source and the liquid ejection head 3, and the liquid is circulated by the liquid supply means. The liquid supply means includes a tank (buffer tank) 1003 as a liquid supply source, an upstream common flow path 161 and a downstream common flow path 162 communicating with the liquid discharge head 3, first and second circulation pumps 1004, 1012, It comprises a valve 237 that opens and closes the downstream flow path 162. The controller 3000 controls each part such as driving the first and second circulation pumps 1004 and 1012, opening and closing the valve 237, driving the recording element in the liquid ejection head 3, and driving the conveying means. A ROM, a RAM, an input / output device, and the like are provided.

  In order for the recording apparatus 1000 to be able to eject ink, it is necessary to fill the liquid ejection head 3 with ink. To fill the liquid discharge head 3 with ink, one or both of the first circulation pump 1001 and the first circulation pump 1012 are driven (ON) to apply ink from the tank 1003 to the liquid discharge head 3. To do. Further, the ink supplied to the liquid discharge head 3 passes through the flow path in the liquid discharge head 3 and the discharge port 13, then flows out of the liquid discharge head 3, and again returns to the ink tank via the downstream common flow path 160. 45 is recovered. Thus, in the present embodiment, ink circulation is performed in which the ink in the tank 1003 returns to the tank 1003 again through the liquid ejection head 3.

  Next, a configuration example of the liquid discharge head 3 is shown in FIGS. FIG. 2 is a perspective view of the liquid discharge head 3. 3A is a sectional view taken along the plane A in FIG. 2, FIG. 3B is a sectional view taken along the plane B in FIG. 2, and FIG. 3C is a sectional view taken along the plane C in FIG. As shown in FIG. 2, a plurality of individual flow path members 50 are disposed on the common flow path member 67, and the recording element substrate 10 is disposed on each of the plurality of individual flow path members 50. As described above, an ejection port array for ejecting ink of four colors of yellow, cyan, magenta, and black is formed on each recording element substrate. By arranging a plurality of recording element substrates along the arrangement direction of the ejection ports in the ejection port array, a long ejection port array is formed corresponding to each ink color.

  Further, as shown in FIG. 3A, the common flow path member 67 is formed with a common supply flow path 211 and a common recovery flow path 212 extending in the arrangement direction on the recording element substrate 10 in parallel. Yes. In addition, in the individual flow path member 50, an individual common flow path 213 and an individual recovery flow path 214 are formed corresponding to each of the plurality of discharge ports constituting the discharge port array. The individual common channel 213 and the individual recovery channel 214 extend along a direction intersecting (orthogonal in the figure) with the arrangement direction of the discharge ports. One end of the individual common channel 213 communicates with the common supply channel 211, and the other end communicates with the ejection port 13 of the recording element substrate 10. The individual recovery channel 214 has one end communicating with the common recovery channel 212 and the other end communicating with the discharge port 13. The ink flows from the common supply channel 211 through the individual common channel 213 to the individual recovery channel 214 via the ejection port 13 and is discharged to the common recovery channel 212.

  Next, the flow of ink in the longitudinal direction of the liquid ejection head 3 will be described with reference to FIGS. 1, 3B, and 3C. First, ink is supplied to the common supply channel 211 and the common recovery channel 212 (see FIGS. 1 and 4) in the common channel member 67 branched from the upstream common channel 161 inside or outside the liquid ejection head 3. Is done. The ink supplied to the common supply channel 211 is divided into the common supply channel 211 and the individual common channel 213. The ink that has flowed into the individual common flow path 213 flows into the ejection port 13 and flows out to the individual recovery flow path 214. The ink that has flowed out to the individual recovery channel 214 merges with the ink supplied to the common recovery channel 212, flows downstream of the common recovery channel 212, and is discharged from the liquid ejection head 3. In the following description, the upstream common channel 161 and the downstream common channel 162 may be collectively referred to as a common channel 160.

  FIG. 4 is an explanatory view schematically showing the ink supply / recovery flow path in the first embodiment. The upstream common flow channel 161 branches into a common supply flow channel 211 and a common recovery flow channel 212 at the connection portion 235. Furthermore, the common supply channel 211 and the common recovery channel 212 merge with the downstream common channel 162 at the connection portion 236. Further, the common supply channel 211 branches off from each individual common channel 213 at the connection portion 231. Reference numeral 231e denotes a connection portion located on the most downstream side of the connection portion between the common supply flow channel 231 and each individual flow channel, and reference numeral 232e denotes a connection portion between the common recovery flow channel 212 and each individual flow channel 214. Among these, the connection part located in the most downstream is shown. As described above, in the present embodiment, the upstream common channel 161 is branched into the common supply channel 211 and the common recovery channel 212, and the common supply channel 211 and the common recovery channel 212 are separated by the downstream common channel 162. It is configured to merge. However, the common supply flow channel 211 and the common recovery flow channel 212 can be configured as separated flow channels and extend upstream and downstream as they are. However, in this case, one pump is required on each of the upstream side and the downstream side of the common supply channel 211 and the common recovery channel 212.

  Here, in order to flow out from the common supply channel 211 to the common recovery channel via the individual common channel 213, the recording element substrate 10, and the individual recovery channel 214, the pressure of the common supply channel 211 is changed to the common recovery channel 211. It must be higher than the pressure in the channel 212. That is, the pressure of the connection portion 231 needs to be higher than the pressure of the connection portion 232. For this purpose, for example, the pressure loss generated in the common recovery flow path 212 between the connection part 235 and the connection part 232 is larger than the pressure loss generated in the common supply flow path 211 between the connection part 235 and the connection part 231. What is necessary is just to comprise. Specifically, the flow resistance can be increased by making the common recovery flow path 212 longer or thinner than the common supply flow path 211, or by putting a throttle.

  In the present embodiment, when ink filling / recovering with respect to the ejection port 13 of the liquid ejection head 3 is performed, the valve (switching means) 237 disposed on the downstream common flow path 162 is closed and then added by the second circulation pump 1004. Press. At this time, in the flow path from the upstream common flow path 161 to the connection part 231e between the common supply flow path 211 and the individual common flow path 213 and the connection part 232e between the common recovery flow path 212 and the individual recovery flow path 214. The bubbles are discharged from the discharge port 13. However, bubbles may remain in the flow path between the connection portion 231e and the valve 237 and in the flow path between the connection portion 232e and the valve 237. The bubbles remaining in the flow path move with the change in the pressure balance between the common supply flow path 211 and the common recovery flow path 212 that occurs when the valve 237 is opened (OPEN), and the individual common flow path 213 and the individual recovery flow path. It flows into the path 214. If bubbles are present in the individual common flow path 213 and the individual recovery flow path 214, there is a possibility that the uniformity of the discharge characteristics will be adversely affected, or the discharge itself may not be performed. That is, the pressure applied at the time of ejection is absorbed by the remaining bubbles, the ejection characteristics change for each ejection port, and the droplet ejection at each ejection port becomes non-uniform. Further, if the remaining bubbles grow due to heating or the like and block the flow path, the supply of ink to the discharge port 13 or the discharge of ink from the discharge port is hindered, and the flow of ink at the discharge port Is inhibited. In this case, the ink is fixed at the ejection port, and the ejection is not performed normally. Further, if both the individual common flow path 213 and the individual recovery flow path 214 are blocked by bubbles, the supply and discharge of the ink to the discharge port 13 are not performed, the ink in the discharge port 13 is insufficient, and the discharge is impossible. Become. That is, it is necessary to suppress the remaining of bubbles generated in the flow path between the connection portion 231e and the valve 237 and between the connection portion 232e and the valve 237 when ink is filled into the liquid ejection head 3 and recovered.

  In order to suppress air bubbles remaining in the flow path between the connection portion 231e and the valve 237 and between the connection portion 232e and the valve 237 when ink is filled into the liquid ejection head 3 and recovered, it is common to close the valve 237 without closing it. It is desirable to fill the supply channel 211, the common recovery channel 212, and the common channel 160 with ink. A series of operations in the filling / recovery mode is shown in the flowchart of FIG. 5, and the ink flow during filling / recovery is shown in FIG.

  When a signal for shifting to the filling / recovery mode is input, as shown in the flowchart of FIG. 5A, the valve 237 is opened (OPEN) and then pressurized by the second circulation pump 1004 (S101, S102). . As a result, as shown in FIG. 6A, the common supply channel 211, the common recovery channel 212, and the common channel 160 are filled with ink (S103). In the pressurizing operation by the second circulation pump 1004, the valve 237 is opened until the bubbles are discharged downstream from the liquid discharge head 3 through the downstream common flow path 162. As the standby time, the time required to fill the common supply flow path 211, the common recovery flow path 212, and the common flow path 160 with ink is measured in advance, and the time is used. Subsequently, as shown in FIG. 6B, the valve 237 is closed (S104), and then the individual common channel 213, the individual recovery channel 214, and the inside of the recording element substrate 10 are pressurized by the second circulation pump 1004. Is filled with ink (S105), and the air bubbles in the channel are discharged from the discharge port 13. With the above operation, filling and recovery of the individual common flow path 213, the individual recovery flow path 214, and the recording element substrate 10 are completed. Finally, the valve 237 is opened (OPEN) (S106), the driving of the second circulation pump 1004 is stopped (OFF) (S107), and the operation is terminated.

  When a signal for shifting to the discharge mode is input after performing the filling / recovery operation, the second circulation pump 1004 and the first circulation pump 1004 are connected to the first circulation pump 1004 as shown in the flowchart of FIG. One or both of the circulation pumps 1012 are operated (S108). At this time, since the remaining bubbles in the respective flow paths in the liquid discharge head 3 and the common flow path 160 are already suppressed, the circulation of ink as shown by the arrows in FIG. The ink discharge port 13 is in a state suitable for ink discharge.

  Further, when the filling / recovering operation and the discharging operation are performed continuously, the driving of the second circulation pump 1004 is not stopped (OFF) at the end of the filling / recovering operation, and the first operation as shown in FIG. The circulation pump 1012 may be driven (ON) to circulate the ink in the liquid discharge head 3.

  As described above, in the present embodiment, after the ink is filled in the common supply channel 211, the common recovery channel 212, and the common channel 160 to discharge the bubbles, the recording element substrate 10 and the individual common channel 213 are individually The recovery channel 214 is filled with ink. Thereby, it is possible to suppress residual bubbles in the liquid discharge head 3 and maintain good discharge performance in the liquid discharge head 3.

  Further, no meniscus is formed at the discharge port 13 during the filling operation. For this reason, when the ink is filled into the common supply channel 211, the common recovery channel 212, and the common channel 160, the pressures of the connection portion 231e and the connection portion 232e are equal to or higher than the atmospheric pressure in order to prevent the inflow of air from the discharge port 13. It is preferable to determine the pressure of the second circulation pump 1004 so that

  Further, during the recovery operation, when the bubbles in the common supply flow path 211, the common recovery flow path 212, and the common flow path 160 flow to the downstream common flow path 162, the pressures of the connection portion 231e and the connection portion 232e are negative. It may be. That is, recovery may be performed by operating only the first circulation pump 1012 instead of the second circulation pump 1004 or by operating both the second circulation pump 1004 and the first circulation pump 1012. However, when operating the pump, the meniscus formed in the discharge port 13, the individual common flow path 213, and the individual recovery flow path 214 is not destroyed, and air does not flow into the common supply flow path 211 or the common recovery flow path 212. It is necessary to stay in the negative pressure range.

  Furthermore, the recording head 3 in this embodiment may be configured to include at least one recording element substrate 10, at least one individual common channel 213, and an individual recovery channel 214. As shown in FIG. 7, even one recording element substrate 10 can be formed.

  A configuration shown in FIG. 9 is given as a first modification of the present embodiment. This first modification has a configuration in which a valve (switching means) 238 is added between the second circulation pump 1004 and the connection portion 235 in the upstream common flow path 161. The valve 238 is configured to supply ink that flows through the common supply channel 211, the common recovery channel 212, and the common channel 160 when the recording element substrate 10, the individual common channel 213, and the individual recovery channel 214 are filled and recovered. Used to reverse the direction of.

  FIG. 8 is a flowchart showing a series of operations in the filling / recovery motion mode in this modification, and a schematic diagram showing the flow of ink during filling / recovery. When a signal for shifting to the filling / recovery mode is input (ON), the valves 237 and 238 are opened (OPEN), and then the second circulation pump 1004 is driven (ON) (S201, 202). Here, as shown in FIG. 9A, the process waits until the common supply channel 211, the common recovery channel 212, and the common channel 160 are filled with ink (S203). Thereafter, as shown in FIG. 9B, the second circulation pump 1004 is turned OFF, the valve 238 is closed (S204, 205), and the first circulation pump 1012 is caused to flow backward (S206). As a result, the ink is pressurized, and as shown in FIG. 9B, the recording element substrate 10, the individual common channel 213, and the individual recovery channel 214 can be filled with ink (S207). After the ink filling is completed, the driving of the pump 1012 is stopped (OFF), the valve 238 is opened (OPEN) (S208, S209), and the series of filling / recovery operations is finished.

  In addition, the first circulation pump 1012 is driven in the reverse direction with the valves 237 and 238 opened, and the ink is allowed to flow to the upstream common flow path 161, whereby the common flow path 160, the common supply flow path 211, and the common recovery flow are It is also possible to fill and recover ink in the path 212.

  Further, the configuration in which the direction of ink flow can be reversed is also effective for filling and recovery when the pressure loss in the common flow path 160, the common supply flow path 211, and the common recovery flow path 212 is large. For example, it is effective when the width of the flow path is reduced as the width of the liquid discharge head 3 in the short direction is reduced, or when the flow path is lengthened by extending the liquid discharge head 3 in the longitudinal direction. That is, in the configuration in which the pressure loss generated in the common flow path 160, the common supply flow path 211, and the common recovery flow path 212 becomes large, the recording element substrate 10 separated from the ink supply side to the liquid ejection head 3, the individual common flow In some cases, it may not be possible to apply sufficient pressure to fill and recover the ink in the channel 213 and the individual recovery channel 214. In this case, if the direction of the ink flowing through the common flow path 160, the common supply flow path 211, and the common recovery flow path 212 can be reversed, the ink can be properly filled and recovered at a location where a sufficient pressure cannot be applied. It can be carried out. That is, when the direction in which the ink flows is reversed, the downstream side when the ink is flowed in the forward direction becomes the upstream side, so that the pressure necessary to fill and recover the ink can be applied. In other words, by reversing the direction of the ink flowing through the common supply channel 211, the common recovery channel 212, and the common channel 160, the influence of the pressure loss that occurs when the ink is fed into the channel is suppressed. Filling and recovery are possible.

  A second modification of the present embodiment in which ink is filled and recovered by causing the ink to flow backward will be described with reference to FIGS. 8B and 9C. The flowchart of FIG. 8B shows a series of operations when filling / recovering according to the second modification, and FIG. 9C is a diagram showing the flow of ink during filling / recovery. In the second modification, first, the common flow path 160, the common supply flow path 211, and the common recovery flow path 212 are filled and recovered as in the first modification (S201 to S203) (S211 to S211). 213). Thereafter, the valve 237 is closed (S237), and the second circulation pump 1004 is driven to send ink toward the downstream common flow path 162 (S215), the individual supply flow path 213, the individual recovery flow path 214, and the printing element substrate. 10 is filled and recovered with ink. As a result, a sufficient pressure can be secured in the portion of the recording element substrate 10, the individual common flow path 213, and the individual recovery flow path 214 that is close to the second circulation pump 1004. Can be filled and recovered. However, there is a possibility that a sufficient pressure cannot be obtained for a portion relatively distant from the second circulation pump 1004. Therefore, in the second modification, after the filling / recovery operation in S215, the valve 237 is opened (OPEN) and the driving of the second circulation pump 1004 is stopped (OFF) (S216, 217). Next, the valve 238 is closed (CLOSE), the first circulation pump 1012 is driven in the reverse direction (ON) (S1012), ink is sent toward the upstream common flow path 161, and the recording element substrate 10 and the individual common flow path 213 are fed. Ink collection / recovery with respect to the individual recovery channel 214 is performed. At this time, a pressure necessary for filling is secured in a portion near the first circulation pump 1012 among the recording element substrate 10, the individual common channel 213, and the individual recovery channel 214. That is, in the filling / recovery operation performed in S215, the ink is reliably filled / recovered even in a portion that is not sufficiently filled / recovered. Thereby, it is possible to more reliably perform ink filling / recovery with respect to all the recording element substrates 10, the individual common flow path 213, and the individual recovery flow path 214 in the liquid ejection head 3.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the configuration shown in FIGS. 1 to 3 is provided. In FIGS. 10 to 19, the same or corresponding parts as those in the first embodiment are denoted by the same reference numerals. A duplicate description is omitted.

  FIG. 10 is an explanatory diagram schematically illustrating an ink supply / recovery circuit according to the second embodiment. In the present embodiment, in order to stabilize the ink circulation flow rate in the ejection port 13, a pressure adjustment mechanism having a function of keeping the pressure difference between the common supply channel 211 and the common recovery channel 212 within a certain range is provided as a printing element substrate. 10 is provided on the upstream side. Specifically, in the common supply channel 211, the upstream pressure adjustment mechanism H is arranged at a position upstream from the connection portion 231 between the recording element substrate 10 and the individual common channel 213. In the common recovery channel 212, the upstream pressure adjustment mechanism L is disposed at a position upstream of the connection portion 232 between the recording element substrate 10 and the individual recovery channel 214. The upstream pressure adjusting mechanisms H and L both adjust the pressure of the fluid after passing through the inside, and the pressure of the fluid adjusted by the upstream pressure adjusting mechanism L is adjusted by the upstream pressure adjusting mechanism H. The pressure is adjusted so as to be lower than the pressure of the fluid. However, since the basic configuration of both pressure adjustment mechanisms is the same except that the pressure adjustment values are different, here, the upstream pressure adjustment mechanism L will be described as an example.

  FIG. 11 is a vertical side view showing the internal structure of the upstream pressure adjustment mechanism L. FIG. The upstream pressure adjustment mechanism L includes a housing portion 255 that forms an outer shell of the pressure adjustment mechanism. In the housing portion 255, a pressure receiving member 251 that is movable due to a pressure difference between the inside and the outside of the housing portion 255, a spring member 252 that acts to relax the operation of the pressure receiving member 251, a pressure receiving member 251, and a spring A valve body 253 that moves in conjunction with the member 252 is provided. The pressure receiving member 251 includes a pressure receiving plate 251a having a predetermined rigidity and a sheet-like flexible member 251b provided around the pressure receiving plate 251a. The flexible member 251b seals between the pressure receiving plate 251a and the housing portion 255, and the fluid that has flowed into the housing portion 255 leaks between the pressure receiving plate 251a and the housing portion 255 to the outside. And a member that does not hinder the mobility of the pressure receiving plate 251a. The pressure receiving plate 251 a is connected to the valve body 253 via the shaft 256 and moves integrally with the valve body 253. The shaft 256 is loosely inserted into the orifice 255a formed in the housing portion 255 so that a predetermined gap is formed, and the pressure adjustment chamber 257 and the liquid communication chamber 258 can communicate with each other through the gap. Yes. The liquid communication chamber 258 communicates with a common recovery channel 212 located on the upstream side of the pressure adjustment mechanism L, and a valve body 253 and a spring member 252 are accommodated therein. In addition, the pressure adjustment chamber 257 is formed by the pressure receiving member 251 and the housing portion 255 and communicates with the common recovery channel 212 located on the downstream side of the pressure adjustment mechanism L.

  In the pressure adjustment mechanism L configured as described above, ink flows into the liquid communication chamber 258 from the common recovery channel 212. At this time, in a state where the valve body 256 is in contact with the casing portion 255 and the orifice 255a is closed, that is, in a state where the valve body 253 is closed (CLOSE), ink from the liquid communication chamber 258 to the pressure adjustment chamber 257 is obtained. Inflow is blocked. In a state where the valve body 256 is separated from the housing portion 255 and a gap is formed between the orifice 255a and the valve body 256, that is, in a state where the valve body 253 is opened (OPEN), the liquid communication chamber 258 is formed. The ink that flows into the ink flows into the pressure adjusting chamber 257 through the orifice 255a.

  The valve body 256 is opened and closed by depressurizing and pressurizing the pressure adjusting chamber 257. When the pressure adjustment chamber 257 is pressurized, the pressure receiving plate 251a moves in a direction in which the pressure adjustment chamber 256 is expanded, that is, in a direction away from the housing portion 255, and the valve body 253 is moved to the housing portion via the shaft 256. In close contact with 255, the orifice 255a is closed (the valve body 253 is closed). On the other hand, when the pressure adjustment chamber 257 is depressurized, the pressure receiving plate 251a moves in a direction in which the pressure adjustment chamber 257 is reduced, that is, in a direction approaching the housing portion 255. As a result, the valve body 253 is pressed from the shaft 256 and is separated from the housing portion 255, and the liquid communication chamber 258 and the pressure adjustment chamber 257 are in communication with each other through the orifice 255a (the valve body 253 is opened). When the valve body 253 is opened, the ink in the liquid communication chamber 258 flows into the pressure adjustment chamber 257 through the orifice 255a. Thus, the pressure adjusting mechanism L has a check valve structure in which the valve body 253 opens when the downstream side is depressurized and the valve body 253 opens when the downstream side is pressurized.

  In the pressure adjustment mechanism L, when the flow rate of the liquid passing through the valve body 253 is small, the degree of opening (opening degree) of the valve body 253 is small and the flow resistance is large. On the contrary, when the flow rate is large, the opening degree of the valve body 253 is large and the flow resistance is small. As described above, one feature of the pressure adjustment mechanism L in the present embodiment is that when the flow rate of ink passing through the valve body 253 changes, the change in pressure loss that occurs when passing through the valve body 253 is reduced. Yes. That is, the pressure downstream of the valve body 253 can be controlled within a certain range regardless of the flow rate, depending on how the valve body 253 is opened. However, since the pressure control becomes impossible when the valve body 253 is fully opened, there is an upper limit to the flow rate at which the pressure control is possible.

  The upstream pressure adjustment mechanism L has been described above, but the upstream pressure adjustment mechanism H has the same configuration and the same function. The difference between the upstream pressure adjustment mechanism H and the downstream pressure adjustment mechanism L is connected to the common supply flow path 211 and is set so that the pressure of the common supply flow path 211 is kept higher than the common recovery flow path 212. Is a point.

  The pressure controlled by each of the upstream pressure adjusting mechanisms H and L is set so that the pressure of the connecting portion 231 is higher than the pressure of the connecting portion 232 and the pressure of the connecting portion 231e is higher than the pressure of the connecting portion 232e. If there is. For example, the upstream pressure adjustment mechanism H arranged in the common supply flow path 211 is made higher than the upstream pressure adjustment mechanism L arranged in the common recovery flow path 212. Furthermore, the difference between the flow path resistance from the outlet of the upstream pressure adjustment mechanism H to the connection portion 231 and the flow path resistance from the outlet of the upstream pressure adjustment mechanism L to the connection portion 232 is made small. As a result, the pressure of the connecting portion 231 is made higher than the pressure of the connecting portion 232.

  As a method of making the pressure to be controlled different between the upstream pressure adjustment mechanism H and the upstream pressure adjustment mechanism L, the spring constant at the time of operation of the spring member 252 and the length of the valve body spring is made different. There are ways to vary the load. As another method, the pressure receiving member 21 is made different in size and the area receiving the pressure difference inside and outside the casing is changed, or the area of the valve body 253 is changed to change the pressure difference before and after passing through the valve structure in the casing. The method of changing the area to receive is mentioned.

  Further, even if the control pressure value of the upstream pressure adjustment mechanism H and the control pressure value of the upstream pressure adjustment mechanism L are approximately the same, the installation height of the upstream pressure adjustment mechanisms H and L may be changed to cause a pressure difference. Is possible. Furthermore, the flow path resistance from the outlet of the upstream pressure adjustment mechanism H to the connection portion 231 is made smaller than the flow path resistance from the outlet of the upstream pressure adjustment mechanism L to the connection portion 232, thereby causing a difference in pressure loss, and connection. You may make it make the pressure of the part 231 higher than the pressure of the connection part 232. FIG. Similarly, the pressure loss generated from the connection portion 231 to the connection portion 231e is made equal to or smaller than the pressure loss generated from the connection portion 232 to the connection portion 232e, and as a result, the pressure of the connection portion 231e is reduced to the pressure of the connection portion 232e. Higher than that.

  In the above configuration, the ink filling / recovering operation with respect to the liquid discharge head 3 is performed by closing the valve 237 disposed on the downstream common flow path 162 and pressurizing the pressure receiving members 21 of the upstream pressure adjusting mechanisms H and L with air or mechanically. It is also possible to forcibly open the valve by pressing. However, in this case, if pressure is applied by the second circulation pump 1004, bubbles remain in the liquid discharge head 3, so that the connection portion 231 e and the connection portion 232 e are connected between the connection portion 231 e and the valve 237 during filling and recovery. There is a possibility that bubbles remain in the flow path between the valve 237 and the valve 237.

  Therefore, in the present embodiment, residual bubbles in the flow path from the connection portion 231e to the valve 237 and residual bubbles in the flow path from the connection portion 232e to the valve 237 are suppressed during the filling / recovery operation. This can be achieved by filling and recovering ink in the common supply channel 211, the common recovery channel 212, and the common channel 160 without closing the valve 237. A series of operations in the filling / recovery is shown in the flowchart of FIG. 12, and the ink flow at the time of filling / recovering is shown in FIG.

  When a signal for shifting to the filling / recovery mode is input (ON), the valves 237 and 238 are opened (OPEN) (S301). Thereafter, the upstream pressure adjusting mechanisms H and L are forced to open the upstream pressure adjusting mechanisms H and L by the air pressure or mechanical pressure (S302). Next, the second circulation pump 1004 is driven (ON) with the valve body 253 opened, and ink is supplied to the common supply channel 211, the common recovery channel 212, and the common channel 160, as shown in FIG. Is filled (S304). As a result, bubbles present in the common supply channel 211, the common recovery channel 212, and the common channel 160 are discharged downstream from the liquid ejection head 3 through the downstream common channel 162.

  Subsequently, the valve 237 is closed (CLOSE) and pressurized by the second circulation pump 1004, so that the individual supply flow path 213, the individual recovery flow path 214, and the recording element substrate 10 are applied to each other as shown in FIG. Ink filling is performed (S306). Thereby, the bubbles in the individual supply channel 213, the individual recovery channel 214, and the recording element substrate 10 are discharged from the ejection port 13, and the ejection / recovery is completed. Finally, after opening the valve 237 and turning off the pump 1004 (S307, 308), the pressure applied to the pressure receiving members 251 of the upstream pressure adjusting mechanisms H, L is released (FREE), and a series of filling and recovery operations Exit.

  After the filling / recovery operation is performed as described above, when a signal for shifting to the discharge mode is input, the operation is performed according to the flowchart shown in FIG. In this discharge mode, as shown in FIG. 13C, with the valve 237 opened, one or both of the second circulation pump 1004 and the first circulation pump 1012 are operated to cause ink to flow. At this time, since the remaining bubbles in the respective flow paths in the liquid discharge head 3 and the common flow path 160 are already suppressed, the circulation of ink as shown by the arrows in FIG. The ink discharge port is in a state suitable for ink discharge.

  When the above-described filling / recovering operation and discharging operation are performed continuously, as shown in the flowchart of FIG. 12B, the second circulation pump 1004 is not turned off at the end of the filling / recovering operation, and the valve 237 is turned off. Can be closed. In addition, the operation | movement of S311-S317 in the flowchart shown in FIG.12 (b) is the same as the operation | movement of S301-S317 of Fig.12 (a). The difference between the operation shown in FIG. 12A and the operation shown in FIG. 12B is that the valve body 237 is opened and then the upstream pressure adjustment mechanisms H and L are released (S318), and The first circulating pump 1012 is driven (S319).

  As described above, in the second embodiment, after the ink is filled into the common supply channel 211, the common recovery channel 212, and the common channel 160 to discharge the bubbles, the recording element substrate 10, the individual common channel The ink is filled into the channel 213 and the individual recovery channel 214. As a result, bubbles remaining in the liquid ejection head 3 can be suppressed.

  Further, in the present embodiment, as in the first embodiment, it is preferable that the pressure of the connection portion 231e and the connection portion 232e is equal to or higher than the atmospheric pressure during the filling operation. Further, in the present embodiment, as in the first embodiment, it is necessary to keep the air in a negative pressure range in which air does not flow into the common supply channel 211 or the common recovery channel 212 during the recovery operation.

  Further, as in the first embodiment, the liquid discharge head 3 in the present embodiment can be configured with a single recording element substrate 10 as shown in FIG.

  Furthermore, the liquid discharge head in the present embodiment can be configured to have only one upstream pressure adjustment mechanism 311. For example, as shown in FIG. 15, an upstream pressure adjustment mechanism 311 is arranged on the upstream common flow path 161, and the pressure loss from the branch of the connection part 235 to the connection part 232 is the pressure loss from the connection part 235 to the connection part 231. It may be made larger. That is, the pressure of the connecting portion 231 is increased by adding a resistance such as a restriction such as a structure in which the flow passage resistance from the connecting portion 235 to the connecting portion 232 is larger than the flow passage resistance from the connecting portion 235 to the connecting portion 231. It suffices if it is configured so that is higher than the pressure of the connection portion 232.

  Further, as a first modification of the present embodiment, when the recording element substrate 10, the individual common flow channel 213, and the individual recovery flow channel 214 are filled and recovered with ink, the common supply flow channel 211 and the common recovery flow channel 212, It is also possible to reverse the direction of ink flowing through the common flow path 160. In this case, the valve 237 is not necessary, and the configuration can be simplified.

  Here, the operation of the first modification of the second embodiment will be described with reference to the flowchart of FIG. 16 and the operation explanatory diagram of FIG. When a signal for shifting to the filling / recovery mode is input, ink is filled into the common supply channel 211, the common recovery channel 212, and the common channel 160 (S401 to 404). Next, in S405, the driving of the second circulation pump 1004 is stopped, and the force applied to forcibly close the valve bodies 253 of the upstream pressure adjustment mechanisms H and L is released (FREE). The circulation pump 1012 is driven (ON) in the reverse direction (S407). As a result, the ink flows backward from the downstream common flow path 162 to the liquid ejection head 3, and the valve body 253 provided in the upstream pressure adjusting mechanisms H and L is pressurized and automatically closed (AUTO CLOSE) (S408). . As a result, the common supply channel 211 and the common recovery channel 212 are blocked by the upstream pressure adjusting mechanisms H and L, and the recording element substrate 10, the individual common channel 213, and the individual recovery channel are pressurized by the first circulation pump 1012. 214 is filled with ink. By filling the ink, bubbles existing in the recording element substrate 10, the individual common flow path 213, and the individual recovery flow path 21 are discharged from the ejection port.

  In addition, the valves 237 and 238 and the upstream pressure adjusting mechanisms H and L are opened, and the first circulation pump 1012 is driven in the reverse direction to flow ink to the upstream common channel 161, whereby the common channel 160, the common supply flow It is also possible to fill and recover the ink in the channel 211 and the common recovery channel 212.

  18 and 19 are diagrams showing a second modification of the second embodiment. In the second modification, the pressure loss of the common flow channel 160, the common supply flow channel 211, and the common recovery flow channel 212 is reduced by performing the operation shown in the flowchart of FIG. 18 in a configuration in which the ink flow can be reversed. Even when it is large, filling and recovery can be performed reliably. In this filling / restoring operation, first, the second circulation pump 1004 is driven in the forward direction with the valve 237 closed and the upstream pressure adjusting mechanisms H and L opened, and the common supply flow path 211 and the common recovery flow path are driven. 212, ink filling / recovery is performed on the common channel 160 (S501 to S504). Next, the valve 237 is closed, and the second circulation pump 1004 is driven in the forward direction. As a result, as shown in FIG. 19A, a portion of the recording element substrate 10, the individual common channel 213, and the individual recovery channel 214 that can secure the pressure necessary for ink filling, that is, the second circulation pump. The portion close to 1004 is filled with ink (S505, 506). Thereafter, the driving of the second circulation pump 1004 is stopped, the force applied to the pressure receiving members 251 of the upstream pressure adjustment mechanisms H and L is released, and the first circulation pump 1012 is moved in the reverse direction with the valve 237 opened. (S507 to 510). By driving the first circulation pump 1012 in the reverse direction, the valve bodies 253 provided in the upstream pressure adjusting mechanisms H and L are automatically closed, and the ink is stored in the recording element substrate 10, the individual common flow path 213, and the individual collection. The flow path 214 is filled. At this time, the recording element substrate 10, the individual common flow path 213, and the individual recovery flow path 214 are filled with ink in a portion where a pressure necessary for filling the ink can be secured, that is, a portion close to the first circulation pump 1012. It becomes. As a result, the ink is filled throughout the recording element substrate 10, the individual common channel 213, and the individual recovery channel 214.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. The third embodiment also has the configuration shown in FIGS. 1 to 3. In FIGS. 20 to 29, the same reference numerals are used for the same or corresponding parts as those of the first and second embodiments. A duplicate description will be omitted.

  FIG. 20 is an explanatory diagram schematically showing an ink supply / recovery flow path in the third embodiment. In the present embodiment, in order to stabilize the ink circulation flow rate in the ejection port 13, a pressure adjustment mechanism having a function of keeping the pressure difference between the common supply channel 211 and the common recovery channel 212 within a certain range is provided as a printing element substrate. 10 is provided on the downstream side (between the connecting portions 231e and 236). Specifically, in the common supply channel 211, the downstream pressure adjusting mechanism H is disposed at a position downstream of the connection portion 231e between the recording element substrate 10 and the individual common channel 213. Further, in the common recovery channel 212, the downstream pressure adjustment mechanism L is disposed at a position downstream of the connection portion 232 e between the recording element substrate 10 and the individual recovery channel 214. The upstream pressure adjusting mechanisms H and L both adjust the pressure of the fluid after passing through the inside, and the pressure of the fluid adjusted by the downstream pressure adjusting mechanism L is adjusted by the upstream pressure adjusting mechanism H. The pressure is adjusted so as to be lower than the pressure of the fluid. However, the basic configuration of both pressure adjustment mechanisms is the same except that the pressure adjustment values are different, and therefore, here, the downstream force adjustment mechanism L will be described as an example.

  In the third embodiment, among the two upstream and downstream space regions formed in the housing portion 265, the upstream space region is used as the pressure adjustment chamber 267 for adjusting the pressure, and the downstream space. The area is a liquid communication chamber 268, which is different from the pressure adjustment mechanism L of the second embodiment. Hereinafter, a specific configuration of the downstream pressure adjusting mechanism L in the third embodiment will be described.

  FIG. 21 is a vertical side view showing the internal structure of the downstream pressure adjusting mechanism L. FIG. The downstream pressure adjustment mechanism L includes a housing portion 265 that forms an outer shell of the downstream pressure adjustment mechanism. In the housing portion 265, a pressure receiving member 261 that is movable due to a pressure difference between the inside and the outside of the housing portion 265, a spring member 262 that acts to relieve the operation of the pressure receiving member 261, a pressure receiving member 261, and a spring A valve body 263 that moves in conjunction with the member 262 is provided. In the figure, reference numeral 269 denotes a spring receiving member that presses against one end of the spring member 262. The pressure receiving member 261 includes a pressure receiving plate 261a having a predetermined rigidity and a sheet-like flexible member 261b provided around the pressure receiving plate 261a. The flexible member 261b seals between the pressure receiving plate 261a and the housing portion 265, and the fluid that has flowed into the housing portion 265 leaks from between the pressure receiving plate 261a and the housing portion 265 to the outside. And a member that does not hinder the mobility of the pressure receiving plate 261a. A valve body 263 is fixed to the pressure receiving plate 261 a, and the valve body 263 is connected to a spring receiving member 268 via a shaft 266. For this reason, the pressure receiving plate 261a, the valve body 253, and the spring receiving member 269 move together. The shaft 266 is loosely inserted into an orifice 265a formed in the casing 265 so that a predetermined gap is formed, and the pressure adjustment chamber 267 and the liquid communication chamber 268 can communicate with each other through the gap. Yes. The pressure adjustment chamber 267 is formed by the pressure receiving member 261 and the housing portion 265 and communicates with the common recovery channel 212 located upstream from the downstream pressure adjustment mechanism L. A valve body 263 is accommodated in the pressure adjustment chamber 267. Further, the liquid communication chamber 268 communicates with a common recovery path 212 located on the downstream side of the downstream pressure adjusting mechanism L, and a spring member 262 and a spring receiving member 269 are accommodated therein.

  In the downstream pressure adjustment mechanism L in the third embodiment configured as described above, ink flows into the pressure adjustment chamber 267 from the common recovery flow path 212. At this time, in a state where the valve body 266 is in contact with the housing portion 265 and the orifice 265a is closed, that is, in a state where the valve body 263 is closed (CLOSE), ink from the pressure adjustment chamber 267 to the liquid communication chamber 268 is obtained. Inflow is blocked. In a state where the valve body 266 is separated from the housing portion 265 and a gap is formed between the orifice 265a and the valve body 266, that is, the valve body 263 is opened (OPEN), the pressure adjustment chamber 267 The ink that has flowed into the liquid flows into the liquid communication chamber 268 through the orifice 265a.

  The valve body 266 is opened and closed by depressurization and pressurization of the pressure adjustment chamber 267. When the pressure adjustment chamber 257 is depressurized, the pressure receiving plate 261a moves in a direction in which the pressure adjustment chamber 256 is reduced, that is, in a direction approaching the housing portion 265. As a result, the valve body 263 fixed to the pressure receiving plate 261a also moves in the same direction and closes the orifice 265a in close contact with the housing portion 255 (the valve body 263 is closed). On the other hand, when the pressure adjustment chamber 265 is pressurized, the pressure receiving plate 261a moves in a direction in which the pressure adjustment chamber 267 is expanded, that is, in a direction away from the housing portion 265. As a result, the valve body 253 also moves in the same direction together with the pressure receiving plate 261a and is separated from the housing portion 255, and the pressure adjustment chamber 267 and the liquid communication chamber 268 communicate with each other via the orifice 265a (the valve body 263 is Open). When the valve body 263 is opened, the ink in the pressure adjusting chamber 267 flows into the liquid communication chamber 268 through the orifice 265a. As described above, the downstream pressure adjusting mechanism L has a check valve structure in which the valve body 263 is opened when the upstream side is pressurized and the valve body 263 is closed when the upstream side is depressurized.

  Further, in the downstream pressure adjustment mechanism L, when the flow rate of the liquid passing through the valve body 263 is small, the opening degree (opening degree) of the valve body 263 is small and the flow resistance is large. On the contrary, when the flow rate is large, the opening degree of the valve body 263 is large and the flow resistance is small. Thus, even in the downstream pressure adjustment mechanism L in the third embodiment, when the ink flow rate passing through the valve body 263 changes, the change in pressure loss that occurs when passing through the valve body 263 is reduced. This is one of the characteristics. However, since pressure control becomes impossible when the valve body 263 is fully opened, there is an upper limit to the flow rate at which pressure control is possible.

  Although the downstream pressure adjustment mechanism L has been described above, the downstream pressure adjustment mechanism H has the same configuration and the same function. The difference between the upstream pressure adjustment mechanism H and the downstream pressure adjustment mechanism L is connected to the common supply flow path 211 and is set so that the pressure of the common supply flow path 211 is kept higher than the common recovery flow path 212. Is a point.

  The pressure values controlled by the downstream pressure adjusting mechanisms H and L are set so that the pressure of the connection portion 231 is higher than the pressure of the connection portion 232 and the pressure of the connection portion 231e is higher than the pressure of the connection portion 232e. It only has to be. For example, the downstream pressure adjustment mechanism H disposed in the common supply flow path 211 is set to be higher than the downstream pressure adjustment mechanism L on the common recovery flow path 14. Furthermore, the difference between the flow path resistance from the inlet of the downstream pressure adjusting mechanism H to the connecting portion 231e and the flow path resistance from the inlet of the downstream pressure adjusting mechanism L to the connecting portion 232e is made small. As a result, the pressure of the connecting portion 231e is made higher than the pressure of the connecting portion 232e. The method of making the pressure to be controlled different between the downstream pressure adjustment mechanism H and the downstream pressure adjustment mechanism L is the same as in the second embodiment.

  Further, even if the control pressure value of the downstream pressure adjustment mechanism H and the control pressure value of the downstream pressure adjustment mechanism L are approximately the same, the installation height of the downstream pressure adjustment mechanisms H and L may be changed to cause a pressure difference. Is possible. Furthermore, the flow path resistance from the inlet of the downstream pressure adjusting mechanism H to the connecting portion 231e is made smaller than the flow path resistance from the inlet of the downstream pressure adjusting mechanism L to the connecting portion 232e, thereby causing a difference in pressure loss and connecting. You may make it make the pressure of the part 231e higher than the pressure of the connection part 232e. Similarly, the pressure loss generated from the connection portion 231 to the connection portion 231e is made equal to or smaller than the pressure loss generated from the connection portion 232 to the connection portion 232e, and as a result, the pressure of the connection portion 231 becomes the pressure of the connection portion 232. Higher than that.

  In the above-described configuration, the ink filling / recovering operation of the liquid discharge head 3 is performed when the second circulation pump 1004 is pressurized with the valve 237 disposed on the downstream common flow path 162 closed, and the liquid discharge head 3 enters the liquid discharge head 3. Bubbles may remain.

  For this reason, in this embodiment, at the time of filling and recovery, residual bubbles in the flow path from the connection portion 231e to the valve 237 and residual bubbles in the flow path from the connection portion 232e to the valve 237 are suppressed, and downstream pressure adjustment is performed. Residual bubbles in the mechanisms L and H are also suppressed. This can be achieved by filling and recovering ink in the common supply channel 211, the common recovery channel 212, and the common channel 160 without closing the valve 237. A series of operations in the filling / recovery is shown in the flowchart of FIG. 22, and the ink flow at the time of filling / recovering is shown in FIG.

  When a signal for shifting to the filling / recovery mode is input (ON), the valve 237 is opened (OPEN) (S601), and then the second circulation pump 1004 is driven (ON) to perform pressurization (S602). By this pressurization, the valve bodies 256 of the downstream pressure adjusting mechanisms H and L are automatically opened, and the common supply channel 211, the common recovery channel 212, and the common channel 160 are filled with ink. As a result, the bubbles remaining in the respective flow paths 211, 212, and 160 are discharged downstream through the downstream supply passage 162. Subsequently, the valve 237 is closed (CLOSE) and pressurized by the second circulation pump 1004, whereby the individual supply channel 213, the individual recovery channel 214, and the recording element substrate 10 are applied to each other as shown in FIG. Ink filling is performed (S606). Thereby, the bubbles in the individual supply channel 213, the individual recovery channel 214, and the recording element substrate 10 are discharged from the ejection port 13. With the above operation, the filling / recovering operation to the individual common flow path 213, the individual recovery flow path 214, and the recording element substrate 10 is completed. Finally, the valve 237 is opened, the driving of the second circulation pump 1004 is turned off, and the series of filling / recovery operations is completed.

  When a signal for shifting to the discharge mode is input, one or both of the second circulation pump 1004 and the first circulation pump 1012 are operated as shown in the flowchart of FIG. 5B with the valve 237 opened. (S108). At this time, since the remaining bubbles in the respective flow paths in the liquid discharge head 3 and the common flow path 160 are already suppressed, the circulation of ink as shown by the arrows in FIG. The ink discharge port 13 is in a state suitable for ink discharge.

  Further, when the filling / recovering operation and the discharging operation are performed continuously, the driving of the second circulation pump 1004 is not stopped (OFF) at the end of the filling / recovering operation, and the first as shown in FIG. The circulation pump 1012 may be driven to circulate the ink in the liquid discharge head 3.

  As described above, in this embodiment, after the common supply channel 211, the common recovery channel 212, and the common channel 160 are filled with ink and the bubbles are discharged, the recording element substrate 10, the individual common channel 213, and the individual recovery channel are collected. Ink is filled into the channel 214. Thereby, it is possible to suppress residual bubbles in the liquid discharge head 3 and maintain good discharge performance in the liquid discharge head 3.

  Further, in the present embodiment, as in the first embodiment, it is preferable that the pressure of the connection portion 231e and the connection portion 232e is equal to or higher than the atmospheric pressure during the filling operation. Further, during the recovery operation, it is necessary to keep the air in a negative pressure range in which air does not flow into the common supply channel 211 or the common recovery channel 212. Further, in the present embodiment, as shown in FIG. 24, a single recording element substrate 10 can be formed.

  Furthermore, the liquid discharge head 3 in the present embodiment only needs to have at least one downstream pressure adjusting mechanism as in the second embodiment. In the liquid discharge head shown in FIG. 25, the downstream pressure adjusting mechanism 312 is arranged on the common flow path 160, and the pressure loss from the connection part 232e to the connection part 236 is higher than the pressure loss from the connection part 231e to the connection part 236. It is configured to be large. That is, the flow path resistance from the connection part 232e to the connection part 236 is configured to be larger than the flow path resistance from the connection part 231e to the connection part 236. As this configuration, for example, a resistor such as a diaphragm is added, but other means can be taken. In short, any configuration may be used as long as the pressure is controlled so that the pressure of the connecting portion 231e is higher than the pressure of the connecting portion 232e.

  When filling and recovering ink in the recording head in the present embodiment, the valve may be forcibly closed by pressurizing the pressure receiving members 251 of the downstream pressure adjusting mechanisms H and L with air or mechanically pressurizing. With this configuration, the valve 237 is not necessary, and the configuration can be simplified. When ink is sent from the second circulation pump 1004 to the downstream common flow path 162 in order to fill the recording element substrate 10, the individual common flow path 213, and the individual recovery flow path 214 with ink, the downstream pressure adjustment mechanisms H and L A valve structure can also be used. That is, the downstream side of the common supply channel 211, the common recovery channel 212, and the common channel 160 is closed with the downstream pressure adjusting mechanisms H and L, so that the recording element substrate 10, the individual common channel 213, and the individual recovery channel are closed. 214 can be filled with ink.

  In this embodiment, the direction of the ink flowing in the common supply channel 211, the common recovery channel 212, and the common channel 160 is used for filling / recovering the recording element substrate 10, the individual common channel 213, and the individual recovery channel 214. In order to carry out the reverse, a valve 238 is required. FIG. 26 is a flowchart showing a first modification of the third embodiment, and FIG. 27 is a diagram showing the ink flow during the filling / recovery operation in the first modification.

  When a signal for shifting to the filling / recovery mode is input, the valves 237 and 238 are opened (OPEN) (S701), the second circulation pump 1004 is driven (ON) (S702), and the common supply flow path 211 is obtained. Then, it waits until the common recovery flow path 212 and the common flow path 160 are filled with ink. Thereafter, the driving of the second circulation pump 1004 is stopped (OFF), and the valve 238 is closed (S704, 705). Next, when the first circulation pump 1012 is driven in the reverse direction and pressurized (S706), the valve bodies 253 of the downstream pressure adjusting mechanisms H and L automatically open, and the recording element substrate 10, the individual common flow path 213, and The individual recovery channel 214 is filled with ink.

  Further, the valves 237 and 238 are opened, and the first circulation pump 1012 is driven in the reverse direction to cause ink to flow to the upstream common channel 161, whereby the common channel 160, the common supply channel 211, and the common recovery channel 212. It is also possible to perform a filling / recovering operation on the.

  FIG. 28 is a flowchart showing the filling / recovering operation in the second modification of the third embodiment, and FIG. 29 is an explanatory diagram showing the ink flow during the filling / recovering operation in the second modification. In this modification, when the operation shown in the flowchart of FIG. 28 is performed in a configuration in which the ink flow can be reversed, the pressure loss in the common flow channel 160, the common supply flow channel 211, and the common recovery flow channel 212 is large. In addition, it is possible to reliably perform filling and recovery.

  When a signal for shifting to the filling / recovery mode is input, first, with the valves 237 and 238 opened, the second circulation pump 1004 is driven in the forward direction, and the common supply flow path 211 and the common recovery flow path 212 are driven. In addition, ink filling / recovery is performed on the common channel 160 (S801 to 803). Next, when the valve 237 is closed (S804), the filling / recovery operation is performed by the second circulation pump 1004 driven in the forward direction. In this filling / recovering operation, as shown in FIG. 29 (a), in the recording element substrate 10, the individual common flow path 213, and the individual recovery flow path 214, a portion where the pressure necessary for ink filling can be secured, that is, the first Ink is filled in a portion close to the two circulation pump 1004 (S805). Thereafter, the driving of the second circulation pump 1004 is stopped (OFF) (S807). Here, the valve 238 is closed (S808), and the first circulation pump 1012 is driven in the reverse direction (S809). When the first circulation pump 1012 is driven in the reverse direction (ON), the valve bodies 253 provided in the upstream pressure adjusting mechanisms H and L are automatically closed, and the ink is supplied to the recording element substrate 10 and the individual common flow path. 213, the individual recovery channel 214 is filled (S810). At this time, in the recording element substrate 10, the individual common flow path 213, and the individual recovery flow path 214, as shown in FIG. 29B, a portion that can secure the pressure necessary for ink filling, that is, the first circulation pump 1012. The ink is filled in a portion close to. As a result, the ink is filled throughout the recording element substrate 10, the individual common channel 213, and the individual recovery channel 214. When the filling / recovery is completed, the valve 238 is finally opened (S811), the driving of the first circulation pump 1012 is stopped (OFF) (S812), and a series of ink filling / recovery operations is completed.

(Fourth embodiment)
FIG. 30 is a side view showing a schematic configuration of the liquid ejection apparatus according to the fourth embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same or equivalent part as the structure shown in FIG. 1, and duplication description is abbreviate | omitted. The fourth embodiment includes two ink tanks 1013 and 1014 so that ink is circulated by a method different from the first to third embodiments. For example, by changing the installation height of the two ink tanks 1013 and 1014 and generating a pressure difference due to the difference in water head, a pump used as power for flowing ink becomes unnecessary, and the apparatus cost can be reduced.

  Further, in the example shown in FIG. 30, the water head difference generated by making the liquid level of the ink tank 1013 higher than the liquid level of the ink tank 1014 is used. That is, ink is supplied from the ink tank 1013 to the common supply channel 211 and the common recovery channel 212 through the upstream common channel 161. The ink supplied to each of the channels 211 and 212 is discharged to the common recovery channel 232 through the individual supply channel 211, the discharge port, and the individual recovery channel 212, the common supply channel 12, and the common recovery channel. After being separated into parts that flow through the flow path 212, they are sent to the downstream common flow path 162 and collected in the ink tank 1014.

  If the ink collected in the ink tank 1014 can be reused, it can be used again for ejection using a pump or a water head difference. If the liquid level of the ink tank 1014 is made higher than the liquid level of the ink tank 1013 with the valve 237 closed and the valve 239 opened, the ink can be returned from the ink tank 1014 to the ink tank 1013 due to a water head difference. it can. Further, by using a device that generates a pressure difference, such as 46 pump, ink can be returned from the ink tank 1014 to the ink tank 1013 in the same manner as the water head difference. It is also possible to use a configuration in which the ink tank 1014 is upstream and the ink tank 1013 is downstream, and a circulation flow is generated by backflow when ink is ejected.

  As described above, if two separated ink tanks are provided upstream and downstream of the liquid discharge head 3 to generate a pressure difference between the two ink tanks, the liquid discharge head is the same as in the first to third embodiments. 3, the ink can be circulated.

  In addition, the ink in the liquid ejection head 3 may be circulated by controlling the pressure using both the upstream pressure adjustment mechanism and the downstream pressure adjustment mechanism shown in the second embodiment and the third embodiment. Is possible.

  As described above, the ink jet recording apparatus according to the present embodiment can generate an ink circulation flow in the liquid ejection head 3. For this reason, it is possible to suppress a drop in the discharge speed of the droplets due to the evaporation of moisture from the discharge port and the modulation of the color material density, and it is possible to form an image with higher accuracy and higher quality.

  Next, fifth and sixth embodiments showing more specifically each part of the liquid ejection apparatus according to the present invention will be described.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, a more specific configuration of each part of the liquid ejection apparatus according to the present invention is shown.

(Description of inkjet recording apparatus)
FIG. 31 is a diagram showing a schematic configuration of a liquid ejection apparatus for ejecting a liquid according to the present invention, in particular, an ink jet recording apparatus (hereinafter also referred to as a recording apparatus) 1000 that performs recording by ejecting ink. The recording apparatus 1000 includes a transport unit 1 that transports the recording medium 2 and a line-type liquid discharge head 3 that is disposed substantially orthogonal to the transport direction of the recording medium 2, and continuously or This is a line type recording apparatus that performs recording in one pass while intermittently conveying. The liquid discharge head 3 includes a negative pressure control unit 230 that controls the pressure (negative pressure) in the circulation path, a liquid supply unit 220 that is in fluid communication with the negative pressure control unit 230, and supply and discharge of ink to the liquid supply unit 220. The liquid connection part 111 used as an exit and the housing 80 are provided. The recording medium 2 is not limited to cut paper but may be a continuous roll medium. The liquid discharge head 3 is capable of full-color recording with cyan C, magenta M, yellow Y, and black K inks, and includes a liquid supply means, a main tank, and a buffer tank (a supply path for supplying liquid to the liquid discharge head 3). Are connected fluidically. The liquid discharge head 3 is electrically connected to an electric control unit that transmits power and a discharge control signal to the liquid discharge head 3. The liquid path and the electric signal path in the liquid discharge head 3 will be described later.

  The recording apparatus 1000 is an ink jet recording apparatus configured to circulate a liquid such as ink between a tank described later and the liquid ejection head 3. The circulation forms are a first circulation form that is circulated by operating two circulation pumps (for high pressure and low pressure) on the downstream side of the liquid discharge head 3, and two circulation pumps on the upstream side of the liquid discharge head 3. There is a second circulation mode in which circulation is performed by operating (for high pressure, for low pressure). Hereinafter, the first circulation mode and the second circulation mode of the circulation will be described.

(Description of circulation mode)
FIG. 32 is a schematic diagram showing a first circulation form of a circulation path applied to the recording apparatus 1000 of the present embodiment. The liquid discharge head 3 is fluidly connected to a first circulation pump (high pressure side) 1001, a first circulation pump (low pressure side) 1002, a buffer tank 1003, and the like. In FIG. 32, for simplification of explanation, only the path through which one color ink of cyan C, magenta M, yellow Y, and black K flows is shown. A circulation path is provided in the liquid discharge head 3 and the recording apparatus main body.

  In the first circulation mode, the ink in the main tank 1006 is supplied to the buffer tank 1003 by the replenishment pump 1005, and then to the liquid supply unit 220 of the liquid discharge head 3 through the liquid connection portion 111 by the second circulation pump 1004. Supplied. Thereafter, the ink adjusted to two different negative pressures (high pressure and low pressure) by the negative pressure control unit 230 connected to the liquid supply unit 220 circulates in two flow paths on the high pressure side and the low pressure side. The ink in the liquid discharge head 3 circulates in the liquid discharge head by the action of the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002 downstream of the liquid discharge head 3, and the liquid connection portion The liquid is ejected from the liquid ejection head 3 via 111 and returned to the buffer tank 1003.

  A buffer tank 1003 that is a sub tank is connected to the main tank 1006, has an air communication port (not shown) that communicates the inside and outside of the tank, and can discharge bubbles in the ink to the outside. A replenishment pump 1005 is provided between the buffer tank 1003 and the main tank 1006. The replenishment pump 1005 transports ink consumed by ejecting (discharging) ink from the ejection port of the liquid ejection head 3 from the main tank 1006 to the buffer tank 1005, such as recording by discharging the ink and recovery of suction.

  The two first circulation pumps 1001 and 1002 draw liquid from the liquid connection portion 111 of the liquid discharge head 3 and flow it to the buffer tank 1003. As the first circulation pump, a positive displacement pump having a quantitative liquid feeding capacity is preferable. Specific examples include a tube pump, a gear pump, a diaphragm pump, and a syringe pump. For example, a general constant flow valve or a relief valve may be arranged at the pump outlet to ensure a constant flow rate. When the liquid discharge head 3 is driven, the first circulation pump (high-pressure side) 1001 and the first circulation pump (low-pressure side) 1002 are operated, so that the ink in the common supply path 211 and the common recovery path 212 has a predetermined flow rate, respectively. Flows. By flowing ink in this way, the temperature of the liquid discharge head 3 during recording is maintained at an optimum temperature. The predetermined flow rate at the time of driving the liquid discharge head 3 is preferably set to be equal to or higher than a flow rate that can be maintained so that the temperature difference between the recording element substrates 10 in the liquid discharge head 3 does not affect the recording image quality. However, if the flow rate is set too high, the negative pressure difference is increased in each recording element substrate 10 due to the pressure loss of the flow path in the liquid discharge unit 300, resulting in uneven density of the image. Therefore, it is preferable to set the flow rate in consideration of the temperature difference and the negative pressure difference between the recording element substrates 10.

  The negative pressure control unit 230 is provided in a path between the second circulation pump 1004 and the liquid discharge unit 300. The negative pressure control unit 230 controls the pressure downstream of the negative pressure control unit 230 (that is, the liquid discharge unit 300 side) even when the ink flow rate in the circulation system fluctuates due to a difference in the discharge amount per unit area. It operates to maintain a preset constant pressure. As the two pressure adjusting mechanisms constituting the negative pressure control unit 230, any pressure control mechanism can be used as long as the pressure downstream of the negative pressure control unit 230 can be controlled with a fluctuation within a certain range around a desired set pressure. Such a mechanism may be used. As an example, a mechanism similar to a so-called “pressure reduction regulator” can be employed. In the circulation channel in the present embodiment, the second circulation pump 1004 pressurizes the upstream side of the negative pressure control unit 230 through the liquid supply unit 220. In this way, the influence of the water head pressure on the liquid discharge head 3 of the buffer tank 1003 can be suppressed, so that the layout flexibility of the buffer tank 1003 in the recording apparatus 1000 can be expanded.

  The second circulation pump 1004 may be any pump that has a lift pressure that is equal to or higher than a certain pressure in the range of the ink circulation flow rate that is used when the liquid discharge head 3 is driven, and a turbo pump or a positive displacement pump can be used. Specifically, a diaphragm pump or the like is applicable. Further, instead of the second circulation pump 1004, for example, a water head tank arranged with a certain water head difference with respect to the negative pressure control unit 230 can be applied. As shown in FIG. 232, the negative pressure control unit 230 includes two pressure adjustment mechanisms each having a different control pressure. Of the two pressure adjustment mechanisms, the relatively high pressure setting side (denoted as H in FIG. 232) and the relatively low pressure side (denoted as L in FIG. 232) pass through the liquid supply unit 220, respectively. A common supply path 211 and a common recovery flow path 212 in the liquid discharge unit 300 are connected. The liquid discharge unit 300 is provided with a common supply path 211, a common recovery path 212, and individual paths 213 (individual supply paths 213a and individual recovery paths 213b) communicating with the respective recording element substrates. A pressure adjustment mechanism H is connected to the common supply flow path 211, and a pressure adjustment mechanism L is connected to the common recovery flow path 212, and a differential pressure is generated between the two common flow paths. Since the individual flow path 213 communicates with the common supply path 211 and the common recovery flow path 212, a part of the liquid passes through the internal flow path of the recording element substrate 10 from the common supply flow path 211 and is shared. A flow (arrow in FIG. 232) that flows to the recovery flow path 212 is generated.

  In this way, in the liquid ejection unit 300, a part of the liquid passes through each recording element substrate 10 while flowing the liquid so as to pass through the common supply flow path 211 and the common recovery flow path 212. Flow occurs. Therefore, the heat generated in each recording element substrate 10 can be discharged to the outside of the recording element substrate 10 by the ink flowing through the common supply channel 211 and the common recovery channel 212. Further, with such a configuration, when recording is performed by the liquid ejection head 3, it is possible to cause ink to flow even in ejection ports and pressure chambers where ejection is not performed. As a result, the viscosity of the ink that has increased in viscosity within the ejection port is reduced, thereby suppressing the increase in the viscosity of the ink. Further, the thickened ink and the foreign matter in the ink can be discharged to the common recovery channel 212. For this reason, the liquid discharge head 3 of the present embodiment can perform high-speed and high-quality recording.

  Further, when filling / recovering the liquid discharge head in the first circulation mode, first, ink is supplied to the common supply channel 211, the common recovery channel 212, and the common channel connected to these channels. Fill and expel bubbles. Thereafter, the recording element substrate 10, the individual common channel 213, and the individual recovery channel 214 are filled with ink. As a result, bubbles remaining in the liquid ejection head 3 can be suppressed. Specifically, the liquid ejection head 3 is filled and recovered by performing the following operations. First, the second circulation pump 1004 and the first circulation pumps 1001 and 1002 are both driven, and the valve in the negative pressure control unit 230 is opened. By this driving, ink reaches the first circulation pumps 1001 and 1002 from the second circulation pump 1004 through the negative pressure control unit 230, the liquid supply unit 220, the liquid discharge unit 300, and the liquid supply unit 220, and is collected in the buffer tank 1003. Is done. Due to the flow of the ink, the common supply channel 211, the common recovery channel 212, and the bubbles existing in the common channel of the liquid ejection head 3 are discharged to the outside of the liquid ejection head 3. After that, the driving of the first circulation pumps 1001 and 1002 is stopped, the valve (not shown) disposed between the buffer tank 1003 and the liquid discharge head 3 is closed, and only the second circulation pump 1004 is driven. Pressurize. As a result, the individual supply channel 213, the individual recovery channel 214, and the internal channel of the recording element substrate 10 provided in the liquid ejection head 3 are filled and recovered.

(Description of second circulation mode)
FIG. 33 is a schematic diagram illustrating a second circulation form that is a circulation form different from the first circulation form described above, among the circulation paths applied to the recording apparatus of the present embodiment. The main difference from the first circulation mode described above is that the two pressure adjusting mechanisms constituting the negative pressure control unit 230 both change the pressure upstream of the negative pressure control unit 230 and set the desired set pressure. It is a point which controls so that it may suppress within a fixed range as a center. Further, the difference from the first circulation mode is that the second circulation pump 1004 acts as a negative pressure source for reducing the pressure downstream of the negative pressure control unit 230. Further, a first circulation pump (high pressure side) 1001 and a first circulation pump (low pressure side) 1002 are arranged on the upstream side of the liquid discharge head 3, and a negative pressure control unit 230 is arranged on the downstream side of the liquid discharge unit 300. This is also different.

  In the second circulation mode, the ink in the main tank 1006 is supplied to the buffer tank 1003 by the replenishment pump 1005. Thereafter, the ink is divided into two flow paths, and circulates in the two flow paths on the high pressure side and the low pressure side by the action of the negative pressure control unit 230 provided in the liquid ejection head 3. The ink divided into the two flow paths on the high pressure side and the low pressure side passes through the liquid connection portion 111 to the liquid discharge head 3 by the action of the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002. Supplied. Thereafter, the ink circulated in the liquid discharge unit 300 by the action of the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002 is connected to the liquid via the liquid supply unit 220 and the negative pressure control unit 230. Discharged from the unit 111. The discharged ink is returned to the buffer tank 1003 by the second circulation pump 1004.

  In the second circulation mode, the negative pressure control unit 230 changes the pressure on the upstream side of the negative pressure control unit 230 (that is, the liquid discharge unit 300 side) even if the flow rate changes due to the change in the discharge amount per unit time. The pressure is kept within a certain range around a preset pressure. In the circulation channel of this embodiment, the second circulation pump 1004 pressurizes the downstream side of the negative pressure control unit 230 via the liquid supply unit 220. In this way, since the influence of the water head pressure of the buffer tank 1003 on the liquid discharge head 3 can be suppressed, the selection range of the layout of the buffer tank 1003 in the recording apparatus 1000 can be widened. Instead of the second circulation pump 1004, for example, a water head tank arranged with a predetermined water head difference with respect to the negative pressure control unit 230 can be applied. In the second circulation mode, similarly to the first circulation mode, the negative pressure control unit 230 includes two pressure adjustment mechanisms each having a different control pressure. Of the two pressure adjustment mechanisms, the high pressure setting side (denoted as H in FIG. 33) and the low pressure setting side (denoted as L in FIG. 3) are common in the liquid discharge unit 300 via the liquid supply unit 220, respectively. The supply path 211 and the common recovery channel 212 are connected. By making the pressure of the common supply channel 211 relatively higher than the pressure of the common recovery channel 212 by the two pressure adjustment mechanisms, the individual channels 213a and the inside of each recording element substrate 10 are provided from the common supply channel 211. An ink flow that flows to the common recovery channel 212 through the channel and the individual channel 213b is generated.

  In such a second circulation mode, an ink flow state similar to that in the first circulation mode can be obtained in the liquid ejection unit 300, but there are two advantages different from those in the first circulation mode. The first advantage is that in the second circulation mode, the negative pressure control unit 230 is disposed downstream of the liquid discharge unit 300, so that dust and foreign matters generated from the negative pressure control unit 230 flow into the liquid discharge unit 300. There is little concern to do. The second advantage is that in the second circulation mode, the maximum required flow rate supplied from the buffer tank 1003 to the liquid ejection head 3 is smaller than in the first circulation mode. The reason is as follows.

  The total of the flow rates in the common supply channel 211 and the common recovery channel 212 when circulating during recording standby is defined as a flow rate A. The value of the flow rate A is defined as the minimum flow rate required to bring the temperature difference in the liquid discharge unit 300 within a desired range when adjusting the temperature of the liquid discharge head 3 during recording standby. Further, when ink is simultaneously discharged from all the discharge ports of the liquid discharge unit 300 (at the time of all discharges), the discharge flow rate is F (discharge amount per discharge operation of one discharge port × discharge frequency × number of discharge ports). Define.

  FIG. 34 is a schematic diagram showing the difference in the amount of ink flowing into the liquid ejection head 3 between the first circulation mode and the second circulation mode. FIG. 34 (a) shows the standby time in the first circulation mode, and FIG. 34 (b) shows the full discharge time in the first circulation mode. FIGS. 34 (c) to 34 (f) show the second circulation form, and FIGS. 34 (c) and 34 (d) show the case where the flow rate F <flow rate A, and FIGS. 34 (e) and 34 (f). Is the case where the flow rate F is greater than the flow rate A, and shows the flow rates during standby and full discharge, respectively.

  In the case of the first circulation mode in which the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002 having a quantitative liquid feeding capacity are arranged on the downstream side of the liquid discharge head 3 (FIG. 34 ( a), (b)), the total set flow rate of the first circulation pump 1001 and the first circulation pump 1002 is the flow rate A. With this flow rate A, the temperature in the liquid discharge unit 300 during standby can be managed. When total discharge is performed by the liquid discharge head 3, the total set flow rate of the first circulation pump 1001 and the first circulation pump 1002 remains at the flow rate A, but the negative pressure generated by the discharge of the liquid discharge head 3. As a result, the maximum flow rate supplied to the liquid discharge head 3 is obtained by adding the consumption amount (flow rate F) for the total discharge to the flow rate A of the total set flow rate. Therefore, the maximum value of the supply amount to the liquid ejection head 3 is the flow rate A + the flow rate F because the flow rate F is added to the flow rate A (FIG. 34B).

  On the other hand, in the case of the second circulation mode in which the first circulation pump 1001 and the first circulation pump 1002 are arranged on the upstream side of the liquid discharge head 3 (FIG. 34 (c) to FIG. 34 (f)), the recording standby The supply amount to the liquid discharge head 3 that is sometimes required is the flow rate A as in the first circulation mode. Therefore, in the second circulation mode in which the first circulation pump 1001 and the first circulation pump 1002 are arranged on the upstream side of the liquid discharge head 3, the flow rate A is higher than the flow rate F (FIG. 34 (c), (d )), The flow rate A is sufficient for the supply amount to the liquid discharge head 3 even during full discharge. At that time, the discharge flow rate from the liquid discharge head 3 is flow rate A−flow rate F (FIG. 34D). However, when the flow rate F is higher than the flow rate A (FIGS. 34 (e) and (f)), assuming that the supply flow rate to the liquid ejection head 3 is the flow rate A, ink shortage occurs in the recording head 3 during all ejections. To do. Therefore, when the flow rate F is higher than the flow rate A, the supply flow rate to the liquid ejection head 3 needs to be the flow rate F. At this time, when all the ejections are performed, the liquid ejection head 3 consumes the flow rate F, so that almost no liquid is discharged from the liquid ejection head 3 (FIG. 34F). When the flow rate F is higher than the flow rate A and discharge is performed but not all discharges, an amount obtained by subtracting the amount consumed by the discharge from the flow rate F is discharged from the liquid discharge head 3.

  As described above, in the case of the second circulation mode, the total value of the set flow rates of the first circulation pump 1001 and the first circulation pump 1002, that is, the maximum value of the necessary supply flow rate is the larger value of the flow rate A or the flow rate F. . Therefore, as long as the liquid discharge unit 300 having the same configuration is used, the maximum value of the required supply amount (flow rate A or flow rate F) in the second circulation mode is the maximum value of the required supply flow rate (flow rate A + flow rate) in the first circulation mode. Smaller than F).

  Therefore, in the case of the second circulation mode, the degree of freedom of the applicable circulation pump is increased. For example, a low-cost circulation pump with a simple configuration is used, or a load of a cooler (not shown) installed in the main body side path is reduced. There is an advantage that the cost of the recording apparatus can be reduced. This advantage increases as the line head has a relatively large value of the flow rate A or the flow rate F. Among line heads, a line head having a long length in the longitudinal direction is more beneficial.

  On the other hand, however, the first circulation mode is advantageous over the second circulation mode. That is, in the second circulation mode, the flow rate that flows through the liquid ejection unit 300 during recording standby is maximum, so that the smaller the amount of ejection per unit area (hereinafter also referred to as a low duty image), A high negative pressure is applied. For this reason, when the flow path width is narrow and the negative pressure is high, a high negative pressure is applied to the discharge port in a low-duty image in which unevenness is easily visible, and so-called satellite droplets are ejected along with the main ink droplets. It may occur and the recording quality may deteriorate.

  On the other hand, in the case of the first circulation mode, a high negative pressure is applied to the discharge port when an image with a large discharge amount per unit area (hereinafter also referred to as a high duty image) is formed. Even if it is difficult to see, there is an advantage that the influence on the image is small. Which of these two circulation forms is selected may be determined in light of the specifications of the liquid discharge head and the recording apparatus main body (discharge flow rate F, minimum circulation flow rate A, and in-head flow path resistance).

  In addition, when filling / recovering the liquid discharge head in the second circulation mode, first, ink is supplied to the common supply channel 211, the common recovery channel 212, and the common channel connected to these channels. Fill and expel bubbles. Thereafter, the recording element substrate 10, the individual common channel 213, and the individual recovery channel 214 are filled with ink. As a result, bubbles remaining in the liquid ejection head 3 can be suppressed.

  Specifically, the following operation is performed. First, both the second circulation pump 1004 and the first circulation pumps 1001 and 1002 are driven. By this driving, ink reaches the second circulation pump 1004 from the first circulation pumps 1001 and 1002 through the liquid supply unit 220, the liquid discharge unit 300, the negative pressure control unit 230, and the liquid supply unit 220, and is collected in the buffer tank 1003. Is done. Due to the flow of the ink, the common supply channel 211, the common recovery channel 212, and the bubbles existing in the common channel of the liquid ejection head 3 are discharged to the outside of the liquid ejection head 3. Thereafter, the driving of the second circulation pump 1004 is stopped, a valve (not shown) disposed between the buffer tank 1003 and the liquid discharge head 3 is closed, and the first circulation pumps 1001 and 1002 are driven to apply pressure. Apply pressure. As a result, the individual supply channel 213, the individual recovery channel 214, and the internal channel of the recording element substrate 10 provided in the liquid ejection head 3 are filled and recovered.

  Also in the fifth embodiment, as in the first to fourth embodiments, it is also possible to apply a filling / recovering operation with a valve or a filling / recovering operation performed by backflowing ink. It is.

(Description of liquid discharge head configuration)
The configuration of the liquid ejection head 3 according to the first embodiment will be described. FIG. 35A and FIG. 35B are perspective views showing the liquid discharge head 3 according to this embodiment. The liquid discharge head 3 has 15 recording element substrates 10 arranged in a straight line (arranged in-line) that can eject inks of four colors of cyan C / magenta M / yellow Y / black K with one recording element substrate 10. This is a line type liquid discharge head. As shown in FIG. 35A, the liquid ejection head 3 includes a recording element substrate 10, a signal input terminal 91 and a power supply terminal 92 electrically connected via the flexible wiring substrate 40 and the electric wiring substrate 90. Prepare. The signal input terminal 91 and the power supply terminal 92 are electrically connected to the control unit of the recording apparatus 1000, and supply an ejection drive signal and electric power necessary for ejection to the recording element substrate 10, respectively. By consolidating the wiring by the electric circuit in the electric wiring board 90, the number of the signal output terminals 91 and the power supply terminals 92 can be reduced as compared with the number of the recording element boards 10. This reduces the number of electrical connections that need to be removed when the liquid ejection head 3 is assembled to the recording apparatus 1000 or when the liquid ejection head is replaced. As shown in FIG. 35B, the liquid connection portions 111 provided at both ends of the liquid ejection head 3 are connected to the liquid supply system of the recording apparatus 1000. Thus, cyan C / magenta M / yellow Y / black K four color inks are supplied from the supply system of the recording apparatus 1000 to the liquid discharge head 3, and ink that has passed through the liquid discharge head 3 is supplied to the supply system of the recording apparatus 1000. It has come to be collected. As described above, the ink of each color can be circulated through the path of the recording apparatus 1000 and the path of the liquid discharge head 3.

  FIG. 36 is an exploded perspective view showing each component or unit constituting the liquid ejection head 3. The liquid discharge unit 300, the liquid supply unit 220, and the electric wiring substrate 90 are attached to the housing 80. The liquid supply unit 220 is provided with a liquid connection portion 111 (see FIG. 33), and the liquid supply unit 220 communicates with each opening of the liquid connection portion 111 in order to remove foreign matters in the supplied ink. A filter 221 (see FIGS. 32 and 33) for each color is provided. The two liquid supply units 220 are each provided with filters 221 for two colors. The liquid that has passed through the filter 221 is supplied to the negative pressure control unit 230 disposed on the liquid supply unit 220 corresponding to each color. The negative pressure control unit 230 is a unit composed of a pressure regulating valve for each color, and the inside of the supply system of the recording apparatus 1000 (which is caused by the fluctuation of the liquid flow rate by the action of a valve or a spring member provided in each of the negative pressure control units 230 The pressure loss change of the supply system upstream of the liquid discharge head 3) is greatly attenuated. Accordingly, the negative pressure control unit 230 can stabilize the negative pressure change on the downstream side (liquid ejection unit 300 side) from the pressure control unit within a certain range. In the negative pressure control unit 230 for each color, two pressure regulating valves for each color are incorporated as described in FIG. The two pressure regulating valves are set to different control pressures, the high pressure side is the common supply channel 211 (see FIG. 2) in the liquid discharge unit 300, and the low pressure side is the common recovery channel 212 (see FIG. 2) and the liquid supply unit. Communicate via 220.

  The casing 80 includes a liquid discharge unit support part 81 and an electric wiring board support part 82, supports the liquid discharge unit 300 and the electric wiring board 90, and ensures the rigidity of the liquid discharge head 3. The electric wiring board support part 82 is for supporting the electric wiring board 90 and is fixed to the liquid discharge unit support part 81 by screws. The liquid discharge unit support portion 81 has a role of correcting the warp and deformation of the liquid discharge unit 300 and ensuring the relative positional accuracy of the plurality of recording element substrates 10, thereby suppressing streaks and unevenness in the recorded matter. . Therefore, the liquid discharge unit support portion 81 preferably has sufficient rigidity, and a metal material such as SUS or aluminum, or a ceramic such as alumina is preferable as the material. The liquid discharge unit support portion 81 is provided with openings 83 and 84 into which the joint rubber 100 is inserted. The liquid supplied from the liquid supply unit 220 is guided to the third flow path member 70 constituting the liquid discharge unit 300 via the joint rubber.

  The liquid discharge unit 300 includes a plurality of discharge modules 200 and a flow path member 210, and a cover member 130 is attached to the surface of the liquid discharge unit 300 on the recording medium side. Here, the cover member 130 is a member having a frame-like surface provided with a long opening 131 as shown in FIG. 36. From the opening 131, the recording element substrate 10 included in the discharge module 200 and the sealing member 130 are sealed. The stopper part 110 (see FIG. 310 described later) is exposed. The frame portion around the opening 131 functions as a contact surface of a cap member that caps the liquid ejection head 3 during recording standby. For this reason, a closed space is formed at the time of capping by applying an adhesive, a sealing material, a filler, or the like along the periphery of the opening 131 and filling the irregularities and gaps on the discharge port surface of the liquid discharge unit 300. It is preferable to do so.

  Next, the configuration of the flow path member 210 included in the liquid discharge unit 300 will be described. As shown in FIG. 36, the flow path member 210 is formed by laminating the first flow path member 50, the second flow path member 60, and the third flow path member 70, and the liquid supplied from the liquid supply unit 220 is removed. Distribute to each discharge module 200. The flow path member 210 is a flow path member for returning the liquid circulating from the discharge module 200 to the liquid supply unit 220. The flow path member 210 is fixed to the liquid discharge unit support portion 81 with screws, thereby suppressing warpage and deformation of the flow path member 210.

  FIGS. 37A to 37F are views showing the front and back surfaces of the respective flow path members of the first to third flow path members. FIG. 37A shows the surface of the first flow path member 50 on the side where the discharge module 200 is mounted, and FIG. 37F shows the liquid discharge unit support portion 81 of the third flow path member 70. The surface on the abutting side is shown. The first flow path member 50 and the second flow path member 60 are joined so that FIGS. 37 (b) and 37 (c), which are contact surfaces of the respective flow path members, face each other. The member and the third flow path member are joined so that FIG. 37D and FIG. 37E, which are contact surfaces of the respective flow path members, face each other. By joining the second flow path member 60 and the third flow path member 70, the eight flow paths extending in the longitudinal direction of the flow path member from the common flow path grooves 62 and 71 formed in each flow path member. Common flow paths (211a, 211b, 211c, 211d, 212a, 212b, 212c, 212d) are formed. As a result, a set of the common supply channel 211 and the common recovery channel 212 is formed in the channel member 210 for each color. Ink is supplied from the common supply flow path 211 to the liquid discharge head 3, and the ink supplied to the liquid discharge head 3 is recovered by the common recovery flow path 212. The communication port 72 (see FIG. 37 (f)) of the third flow path member 70 communicates with each hole of the joint rubber 100 and is in fluid communication with the liquid supply unit 220 (see FIG. 36). On the bottom surface of the common channel groove 62 of the second channel member 60, there are communication ports 61 (a communication port 61-1 communicating with the common supply channel 211 and a communication port 61-2 communicating with the common recovery channel 212). A plurality are formed and communicate with one end of the individual flow channel 52 of the first flow channel member 50. A communication port 51 is formed at the other end of the individual flow channel 52 of the first flow channel member 50, and is in fluid communication with the plurality of discharge modules 200 via the communication port 51. The individual flow channel 52 enables the flow channels to be concentrated on the center side of the flow channel member.

  It is preferable that the first to third flow path members are made of a material having corrosion resistance against a liquid and a low linear expansion coefficient. As a material, for example, a composite material (resin material) in which inorganic fillers such as silica fine particles and fibers are added using alumina, LCP (liquid crystal polymer), PPS (polyphenyl sulfide), and PSF (polysulfone) as a base material is preferably used. be able to. As a method of forming the flow path member 210, three flow path members may be laminated and bonded to each other. When a resin composite resin material is selected as the material, a joining method by welding may be used.

  FIG. 38 shows the α part of FIG. 37 (a), and the flow path in the flow path member 210 formed by joining the first to third flow path members is the first flow path member 50. It is the perspective view which expanded and showed a part from the surface side in which the discharge module 200 is mounted. The common supply flow path 211 and the common recovery flow path 212 are alternately arranged from the flow paths at both ends. Here, the connection relation of each flow path in the flow path member 210 will be described.

  The channel member 210 is provided with a common supply channel 211 (211a, 211b, 211c, 211d) and a common recovery channel 212 (212a, 212b, 212c, 212d) extending in the longitudinal direction of the liquid ejection head 3 for each color. It has been. A plurality of individual supply channels (213 a, 213 b, 213 c, and 213 d) formed by the individual channel grooves 52 are connected to the common supply channel 211 of each color via the communication port 61. In addition, a plurality of individual recovery channels (214a, 214b, 214c, 214d) formed by the individual channel grooves 52 are connected to the common recovery channel 212 of each color via the communication port 61. With such a flow path configuration, it is possible to collect ink from each common supply flow path 211 via the individual supply flow path 213 to the recording element substrate 10 located at the center of the flow path member. Ink can be recovered from the recording element substrate 10 to each common recovery channel 212 via the individual recovery channel 214.

  FIG. 39 is a view showing a cross section taken along line IX-IX in FIG. Each individual recovery channel (214a, 214c) communicates with the discharge module 200 via the communication port 51. In FIG. 39, only the individual recovery flow paths (214a, 214c) are shown, but in another cross section, the individual supply flow path 213 and the discharge module 200 communicate with each other as shown in FIG. A flow path for supplying ink from the first flow path member 50 to the recording element 15 provided on the recording element substrate 10 is formed in the support member 30 and the recording element substrate 10 included in each ejection module 200. . Further, the support member 30 and the recording element substrate 10 are provided with a flow path for collecting (circulating) a part or all of the liquid supplied to the recording element 15 to the first flow path member 50.

  Here, the common supply flow path 211 of each color is connected to the corresponding negative pressure control unit 230 (high pressure side) via the liquid supply unit 220, and the common recovery flow path 212 is connected to the negative pressure control unit 230. (Low pressure side) and the liquid supply unit 220 are connected. By this negative pressure control unit 230, a differential pressure (differential pressure) is generated between the common supply channel 211 and the common recovery channel 212. For this reason, as shown in FIGS. 38 and 39, in the liquid discharge head of the present embodiment in which the respective flow paths are connected, the common supply flow path 211 to the individual supply flow paths 213a to the recording element substrates 10 to 10 are individually used for each color. A flow that flows in order from the recovery channel 213b to the common recovery channel 212 is generated.

(Description of discharge module)
FIG. 34 (a) is a perspective view showing one discharge module 200, and FIG. 34 (b) is an exploded view thereof. As a manufacturing method of the discharge module 200, first, the recording element substrate 10 and the flexible wiring substrate 40 are bonded onto the support member 30 provided with the liquid communication port 31 in advance. Thereafter, the terminals 16 on the recording element substrate 10 and the terminals 41 on the flexible wiring substrate 40 are electrically connected by wire bonding, and then the wire bonding portion (electrical connection portion) is covered with the sealing material 110 and sealed. . A terminal 42 of the flexible wiring board 40 opposite to the recording element substrate 10 is electrically connected to a connection terminal 93 (see FIG. 36) of the electric wiring board 90. The support member 30 is a support member that supports the recording element substrate 10, and is a flow path member that fluidly communicates the recording element substrate 10 and the flow path member 210. Therefore, the support member 30 has high flatness and is sufficiently high. Those that can be reliably bonded to the recording element substrate are preferable. As a material, for example, alumina or a resin material is preferable.

(Description of structure of recording element substrate)
41A shows a plan view of the surface of the recording element substrate 10 on the side where the discharge ports 13 are formed, and FIG. 41B shows an enlarged view of the portion indicated by A in FIG. 341A. FIG. 41 (c) shows a plan view of the back surface of FIG. 41 (a). Here, the configuration of the recording element substrate 10 in the present embodiment will be described. As shown in FIG. 41A, the discharge port forming member 12 of the recording element substrate 10 is formed with four rows of discharge port rows corresponding to the respective ink colors. Hereinafter, the direction in which the discharge port array in which the plurality of discharge ports 13 are arranged is referred to as “discharge port array direction”. As shown in FIG. 41 (b), recording elements 15 as heating elements for foaming the liquid with thermal energy are arranged at positions corresponding to the respective ejection ports 13. A partition 22 defines a pressure chamber 23 having the recording element 15 therein. The recording element 15 is electrically connected to the terminal 16 by electrical wiring (not shown) provided on the recording element substrate 10. The recording element 15 generates heat based on the pulse signal input from the control circuit of the recording apparatus 1000 via the electric wiring board 90 (see FIG. 36) and the flexible wiring board 40 (see FIG. 40), and boils the liquid. Let The liquid is discharged from the discharge port 13 by the foaming force due to the boiling. As shown in FIG. 41B, along each discharge port array, a liquid supply path 18 extends on one side, and a liquid recovery path 19 extends on the other side. The liquid supply path 18 and the liquid recovery path 19 are channels extending in the direction of the discharge port array provided in the recording element substrate 10 and communicate with the discharge port 13 via the supply port 17a and the recovery port 17b, respectively.

  As shown in FIG. 41 (c), a sheet-like cover plate 20 is laminated on the back surface of the recording element substrate 10 on which the discharge ports 13 are formed. A plurality of openings 21 communicating with the passage 18 and the liquid recovery passage 19 are provided. In the present embodiment, three openings 21 are provided in the cover plate 20 for one of the liquid supply paths 18 and two openings 21 for one of the liquid recovery paths 19. As shown in FIG. 41 (b), each opening 21 of the cover plate 20 communicates with a plurality of communication ports 51 shown in FIG. 37 (a). The cover plate 20 preferably has sufficient corrosion resistance to the liquid, and high accuracy is required for the opening shape and the opening position of the opening 21 from the viewpoint of preventing color mixing. Therefore, it is preferable to use a photosensitive resin material or a silicon plate as the material of the cover plate 20 and provide the opening 21 by a photolithography process. As described above, the cover plate 20 converts the pitch of the flow path by the openings 21, and considering the pressure loss, the cover plate 20 is preferably thin and is preferably formed of a film-like member.

  FIG. 42 is a perspective view showing cross sections of the recording element substrate 10 and the cover plate 20 along XII-XII in FIG. Here, the flow of the liquid in the recording element substrate 10 will be described. The cover plate 20 has a function as a lid that forms part of the walls of the liquid supply path 18 and the liquid recovery path 19 formed on the substrate 11 of the recording element substrate 10. The recording element substrate 10 includes a substrate 11 formed of Si and a discharge port forming member 12 formed of a photosensitive resin, and a cover plate 20 is bonded to the back surface of the substrate 11. A recording element 15 is formed on one side of the substrate 11 (see FIG. 41), and a liquid supply path 19 and a liquid recovery path 18 extending along the ejection port array are formed on the back side thereof. Grooves are formed. The liquid supply path 18 and the liquid recovery path 19 formed by the substrate 11 and the cover plate 20 are connected to the common supply path 211 and the common recovery path 212 in the flow path member 210, respectively. And a liquid recovery path 19 has a differential pressure. When recording is performed by discharging liquid from the discharge port 13, the liquid in the liquid supply path 18 provided in the substrate 11 is supplied to the supply ports 17 a and 17 a by the differential pressure. It flows to the liquid recovery path 19 via the pressure chamber 22 and the recovery port 17b (arrow C in FIG. 42). With this flow, the thickened ink, bubbles, foreign matters, and the like generated by evaporation from the ejection port 13 can be collected in the liquid collection path 19 in the ejection port 13 and the pressure chamber 22 where recording is paused. Further, it is possible to prevent the ink in the ejection port 13 and the pressure chamber 22 from being thickened. The liquid recovered into the liquid recovery path 19 passes through the opening 21 of the cover plate 20 and the liquid communication port 31 of the support member 30 (see FIG. 40b). They are collected in the order of the collection channel 212 and collected to the supply path of the recording apparatus 1000. That is, the liquid supplied from the recording apparatus main body to the liquid discharge head 3 flows in the following order, and is supplied and recovered.

  The liquid first flows into the liquid ejection head 3 from the liquid connection part 111 of the liquid supply unit 220. The liquid is the joint rubber 100, the communication port 72 and the common channel groove 71 provided in the third channel member, the common channel groove 62 and the communication port 61 provided in the second channel member, and the first channel. The individual flow channel 52 and the communication port 51 provided in the member are supplied in this order. Thereafter, the pressure is supplied to the pressure chamber 23 through the liquid communication port 31 provided in the support member 30, the opening 21 provided in the cover plate 20, the liquid supply path 18 and the supply port 17 a provided in the substrate 11 in order. Of the liquid supplied to the pressure chamber 23, the liquid that has not been discharged from the discharge port 13 is the recovery port 17 b and the liquid recovery path 19 provided in the substrate 11, the opening 21 provided in the cover plate 20, and the support member 30. It flows through the liquid communication port 31 provided in the order. Thereafter, the liquid is provided in the communication port 51 and the individual flow channel 52 provided in the first flow channel member, the communication port 61 and the common flow channel 62 provided in the second flow channel member, and the third flow channel member 70. The common channel groove 71, the communication port 72, and the joint rubber 100 are sequentially flowed. Then, the liquid flows from the liquid connection part 111 provided in the liquid supply unit 220 to the outside of the liquid discharge head 3.

  In the form of the first circulation form shown in FIG. 2, the liquid flowing in from the liquid connecting portion 111 is supplied to the joint rubber 100 after passing through the negative pressure control unit 230. In the second circulation mode shown in FIG. 3, the liquid recovered from the pressure chamber 23 passes through the joint rubber 100 and then passes from the liquid connection unit 111 to the outside of the liquid discharge head via the negative pressure control unit 230. To flow. Further, not all the liquid that has flowed from one end of the common supply channel 211 of the liquid discharge unit 300 is supplied to the pressure chamber 23 via the individual supply channel 213a. That is, there is a liquid that flows from one end of the common supply channel 211 and flows from the other end of the common supply channel 211 to the liquid supply unit 220 without flowing into the individual supply channel 213a. As described above, by providing a path that flows without passing through the recording element substrate 10, even if the recording element substrate 10 includes a fine flow path having a high flow resistance as in the present embodiment, the liquid is provided. The reverse flow of the circulating flow can be suppressed. As described above, in the liquid discharge head 3 of the present embodiment, it is possible to suppress the increase in the viscosity of the liquid in the pressure chamber 23 and the vicinity of the discharge port. High-quality recording can be performed.

(Description of positional relationship between recording element substrates)
FIG. 43 is a plan view partially enlarged showing the adjacent portion of the recording element substrate in two adjacent ejection modules. In this embodiment, a substantially parallelogram recording element substrate is used. The respective ejection port arrays (14a to 14d) in which the ejection ports 13 in each recording element substrate 10 are arranged are arranged so as to be inclined at a certain angle with respect to the conveyance direction of the recording medium. The ejection port arrays in the adjacent portions of the recording element substrates 10 are configured such that at least one ejection port overlaps in the conveyance direction of the recording medium. In FIG. 43, the two discharge ports on the line D are in a relationship of overlapping each other. With such an arrangement, even if the position of the recording element substrate 10 is slightly deviated from the predetermined position, black stripes and white spots in the recorded image can be made inconspicuous by driving control of the overlapping discharge ports. Even when a plurality of recording element substrates 10 are arranged in a straight line (in-line) instead of in a staggered arrangement, the recording elements are controlled while suppressing an increase in the length of the liquid ejection head 10 in the recording medium conveyance direction by the configuration shown in FIG. It is possible to take measures against black streaks and white spots at the connecting portions of the substrates 10. In this embodiment, the main plane of the recording element substrate is a parallelogram. However, the present invention is not limited to this, and the configuration of the present invention is preferable even when a rectangular, trapezoidal or other shape recording element substrate is used. Can be applied.

(Sixth embodiment)
Hereinafter, configurations of an ink jet recording apparatus 2000 and a liquid discharge head 2003 according to a sixth embodiment of the present invention will be described with reference to the drawings. In the following description, only the parts different from the first embodiment will be mainly described, and the description of the same parts as in the first embodiment will be omitted.

(Description of inkjet recording apparatus)
FIG. 51 is a diagram showing an ink jet recording apparatus 2000 that can apply the present embodiment and performs recording by discharging a liquid. The recording apparatus 2000 according to the present embodiment performs full-color recording on a recording medium by arranging four monochrome liquid ejection heads 2003 corresponding to cyan C, magenta M, yellow Y, and black K inks in parallel. Different from the first embodiment. In the first embodiment, the number of ejection port rows that can be used per color is one, whereas in this embodiment, the number of ejection port rows that can be used per color is 20. For this reason, it is possible to perform very high-speed recording by appropriately recording the recording data to a plurality of ejection port arrays. Furthermore, even if there is a discharge port that does not discharge, reliability is improved by interpolating discharge from the discharge ports in other rows that are at positions corresponding to the discharge direction of the recording medium. And suitable for commercial records. As in the first embodiment, the supply system of the recording apparatus 2000, the buffer tank 1003 (see FIGS. 32 and 33), and the main tank 1006 (see FIGS. 32 and 33) are fluids for each liquid discharge head 2003. Connected. Each liquid discharge head 2003 is electrically connected to an electric control unit that transmits power and a discharge control signal to the liquid discharge head 2003.

(Explanation of circulation route)
As in the fifth embodiment, as the liquid circulation path between the recording apparatus 2000 and the liquid discharge head 2003, the first and second circulation forms shown in FIG. 32 or FIG. 33 are used as in the first embodiment. Can do. Further, the filling / recovering operation for the liquid discharge head 2003 can be performed in the same manner as in the fifth embodiment.

(Description of liquid discharge head structure)
44 (a) and 44 (b) are perspective views showing a liquid discharge head 2003 according to the present embodiment. Here, the structure of the liquid discharge head 2003 according to the present embodiment will be described. The liquid ejection head 2003 is an ink jet type line recording head that includes 16 recording element substrates 2010 arranged in a straight line in the longitudinal direction of the liquid ejection head 2003 and is capable of recording with one color liquid. The liquid ejection head 2003 includes a liquid connection unit 111, a signal input terminal 91, and a power supply terminal 92, as in the first embodiment. However, since the liquid discharge head 2003 of this embodiment has more discharge port arrays than the first embodiment, the signal output terminal 91 and the power supply terminal 92 are arranged on both sides of the liquid discharge head 2003. This is to reduce voltage drop and signal transmission delay that occur in the wiring portion provided on the recording element substrate 2010.

  FIG. 45 is a perspective exploded view showing the liquid discharge head 2003, and shows each component or unit constituting the liquid discharge head 2003 divided for each function. The role of each unit and member and the order of liquid circulation in the liquid discharge head are basically the same as those in the first embodiment, but the functions for ensuring the rigidity of the liquid discharge head are different. In the first embodiment, the liquid discharge head support portion 81 mainly secures the liquid discharge head rigidity. However, in the liquid discharge head 2003 of the second embodiment, the second flow path member 2060 included in the liquid discharge unit 2300 is used. This ensures the rigidity of the liquid discharge head. In the present embodiment, the liquid discharge unit support portion 81 is connected to both ends of the second flow path member 2060, and the liquid discharge unit 2300 is mechanically coupled to the carriage of the recording apparatus 2000 to provide a liquid discharge head 2003. Perform positioning. The liquid supply unit 2220 including the negative pressure control unit 2230 and the electrical wiring board 90 are coupled to the liquid discharge unit support portion 81. Each of the two liquid supply units 2220 includes a filter (not shown).

  The two negative pressure control units 2230 are set so as to control the pressure with different relatively high and low negative pressures. Further, as shown in FIG. 344, when the high-pressure side and low-pressure side negative pressure control units 2230 are installed at both ends of the liquid discharge head 2003, a common supply flow path extending in the longitudinal direction of the liquid discharge head 2003 is provided. And the flow of liquid in the common recovery channel face each other. In such a configuration, heat exchange is promoted between the common supply channel and the common recovery channel, and a temperature difference between the two common channels is reduced. Accordingly, there is an advantage that a temperature difference in each of the recording element substrates 2010 provided along the common flow path is reduced, and recording unevenness due to the temperature difference is less likely to occur.

  Next, details of the flow path member 2210 of the liquid discharge unit 2300 will be described. As shown in FIG. 345, the flow path member 2210 is a laminate of the first flow path member 2050 and the second flow path member 2060, and distributes the liquid supplied from the liquid supply unit 2220 to each discharge module 2200. To do. The flow path member 2210 functions as a flow path member for returning the liquid circulating from the discharge module 2200 to the liquid supply unit 2220. The second flow path member 2060 of the flow path member 2210 is a flow path member in which a common supply flow path and a common recovery flow path are formed, and has a function of mainly responsible for the rigidity of the liquid discharge head 2003. For this reason, as a material of the 2nd flow path member 2060, what has sufficient corrosion resistance with respect to a liquid and high mechanical strength is preferable. Specifically, SUS, Ti, alumina or the like can be used.

  FIG. 46A is a view showing a surface of the first flow path member 2050 on which the discharge module 2200 is mounted, and FIG. 46B shows the back surface thereof, and the second flow path member 2060 is shown. It is the figure which showed the surface contact | abutted with. Unlike the first embodiment, the first flow path member 2050 in the present embodiment is formed by arranging a plurality of members corresponding to each discharge module 2200 adjacent to each other. By adopting such a divided structure, a plurality of modules can be arranged to correspond to the length of the liquid discharge head 2003. For example, a relatively long scale corresponding to the B2 size or longer The present invention can be particularly preferably applied to the liquid discharge head. As shown in FIG. 46 (a), the communication port 51 of the first flow path member 2050 is in fluid communication with the discharge module 2200. As shown in FIG. 46 (b), the first flow path member 2050 is individually connected. The communication port 53 is in fluid communication with the communication port 61 of the second flow path member 2060. 46C shows a surface of the second flow path member 60 that is in contact with the first flow path member 2050, and FIG. 46D is a cross-sectional view of the central portion in the thickness direction of the second flow path member 60. FIG. 46E is a diagram showing a surface of the second flow path member 2060 that comes into contact with the liquid supply unit 2220. The functions of the flow path and the communication port of the second flow path member 2060 are the same as those for one color in the first embodiment. One of the common flow channel grooves 71 of the second flow channel member 2060 is a common supply flow channel 2211 shown in FIG. 47, which will be described later, and the other is a common recovery flow channel 2212, respectively. The liquid is supplied from one end side to the other end side. In the present embodiment, unlike the first embodiment, the liquid flows in the common supply channel 2211 and the common recovery channel 2212 are in opposite directions.

  FIG. 47 is a perspective view showing a liquid connection relationship between the recording element substrate 2010 and the flow path member 2210. In the flow path member 2210, a set of a common supply flow path 2211 and a common recovery flow path 2212 extending in the longitudinal direction of the liquid discharge head 2003 are provided. The communication port 61 of the second flow channel member 2060 is connected to the individual communication port 53 of each first flow channel member 50 in alignment, and is connected to the common supply flow channel from the communication port 72 of the second flow channel member 2060. A liquid supply path that communicates with the communication port 51 of the first flow path member 2050 via 2211 is formed. Similarly, a liquid supply path that communicates from the communication port 72 of the second flow channel member 2060 to the communication port 51 of the first flow channel member 2050 via the common recovery flow channel 2212 is also formed.

  48 is a view showing a cross section taken along line XVIII-XVIII in FIG. 47. The common supply channel 2211 is connected to the discharge module 2200 via the communication port 61, the individual communication port 53, and the communication port 51. Although not shown in FIG. 48, it is apparent with reference to FIG. 47 that in another cross section, the common recovery flow path 2212 is connected to the discharge module 2200 through a similar path. Similarly to the first embodiment, each ejection module 2200 and the recording element substrate 2010 are formed with a flow path communicating with each ejection port, and part or all of the supplied liquid pauses the ejection operation. It can be recirculated through the outlet. Similarly to the first embodiment, the common supply flow path 2211 is connected to the negative pressure control unit 2230 (high pressure side), and the common recovery flow path 2212 is connected to the negative pressure control unit 2230 (low pressure side) and the liquid supply unit 2220. Connected. Therefore, the differential pressure causes a flow that flows from the common supply flow path 2211 to the common recovery flow path 2212 through the discharge port of the recording element substrate 2010.

(Description of discharge module)
FIG. 49 (a) is a perspective view showing one discharge module 2200, and FIG. 49 (b) is an exploded view thereof. The difference from the first embodiment is that a plurality of terminals 16 are arranged on both sides (long sides of the printing element substrate 2010) along the plurality of ejection port array directions of the printing element substrate 2010, respectively. is there. Accordingly, two flexible wiring boards 40 that are electrically connected to the recording element substrate 2010 are also arranged on one recording element substrate 2010. This is because the number of ejection port arrays provided on the recording element substrate 2010 is 20, which is significantly larger than the eight arrays in the first embodiment, and the maximum distance from the terminal 16 to the recording element is shortened. This is to reduce a voltage drop and a signal delay that occur in the wiring portion in the recording element substrate 2010. Further, the liquid communication port 31 of the support member 2030 is provided in the recording element substrate 2010 and is opened so as to straddle all the ejection port arrays. Other points are the same as in the first embodiment.

(Description of structure of recording element substrate)
FIG. 50A is a schematic diagram of a surface on which the ejection port 13 of the recording element substrate 2010 is disposed, and FIG. 50C is a schematic diagram illustrating a back surface of the surface of FIG. 350A. FIG. 50B is a schematic diagram showing the surface of the recording element substrate 2010 when the cover plate 2020 provided on the back side of the recording element substrate 2010 is removed in FIG. As shown in FIG. 50B, the liquid supply path 18 and the liquid recovery path 19 are alternately provided on the back surface of the recording element substrate 2010 along the discharge port array direction. Although the number of ejection port arrays is greatly increased as compared with the first embodiment, the essential difference from the first embodiment is that the terminals 16 are arranged in the ejection port array direction of the recording element substrate as described above. It is arranged on both sides along. A set of liquid supply path 18 and liquid recovery path 19 is provided for each discharge port array, and an opening 21 communicating with the liquid communication port 31 of the support member 2030 is provided on the cover plate 2020. The basic configuration is the same as that of the first embodiment.

(Other embodiments)
In addition, the description of the said embodiment does not limit the scope of the present invention. As an example, in the present embodiment, a thermal method in which bubbles are generated by a heating element to discharge a liquid has been described. However, the present invention can also be applied to a liquid discharge head that employs a piezo method and other liquid discharge methods. it can.

  In the above embodiment, when the recording head is filled and recovered with ink, a liquid different from the ink used for recording, such as a liquid for storage or a liquid for initial filling with high fluidity, for example, a liquid with high wettability. After filling, the ink used for recording may be replaced.

  As an embodiment of the present invention, an ink jet recording apparatus (recording apparatus) in which liquid such as ink is circulated between a tank and a liquid discharge head has been described, but other forms may be used. For example, without circulating ink, two tanks are provided on the upstream side and downstream side of the liquid discharge head, and the ink in the pressure chamber of the liquid discharge head flows by flowing ink from one tank to the other tank. There may be.

  In this embodiment, an example using a so-called line type head having a length corresponding to the width of the recording medium has been described. However, a so-called serial type liquid ejection head that performs recording while scanning the recording medium. The present invention can also be applied to. Examples of the serial type liquid discharge head include a configuration in which one recording element substrate that discharges black ink and one recording element substrate that discharges color ink are mounted, but the present invention is not limited thereto. That is, a mode in which a plurality of recording element substrates are arranged so that the discharge ports overlap in the discharge port array direction, and a short liquid discharge head shorter than the width of the recording medium is created, and the recording medium is scanned with respect to the recording medium It may be.

13 Discharge port 10 Recording element substrate,
213 Individual supply channel 214 Individual recovery channel 211 Common supply channel 212 Common recovery channel;
237 valve (first switching means)
238 valve (second switching means)
239 Valve (switching means)
1000 Inkjet recording device (liquid ejection device)
1004 Second circulation pump (second pressurizing means)
1012 First circulation pump (first pressurizing means)
3000 controller (control means)
H Pressure adjustment mechanism L Pressure adjustment mechanism

Claims (11)

A recording element substrate having a discharge port for discharging a liquid;
A supply flow path for supplying a liquid to the recording element substrate;
A recovery flow path for recovering liquid from the recording element substrate;
A common supply channel for supplying liquid to the supply channel;
A common recovery channel for recovering liquid from the recovery channel;
Pressurizing means for applying pressure to the common supply channel and the common recovery channel;
Switching means for switching between communication and blocking of the common supply channel and the common recovery channel;
Control means for controlling the pressurizing means,
The control means fills the common supply flow path and the common recovery flow path with liquid by driving the pressurizing means in a state where the common supply flow path and the common recovery flow path are in communication with each other; and By pressurizing the liquid filled in the common supply channel and the common recovery channel with the pressurizing unit in a state where the common supply channel and the common recovery channel are blocked by the switching unit, the supply flow A liquid discharge apparatus, wherein a liquid is filled in a path, the discharge port, and the recovery flow path.   2. The liquid ejection apparatus according to claim 1, wherein the switching unit is disposed downstream of the recording element substrate in the liquid flow direction in the common supply channel and the common recovery channel.   The liquid ejecting apparatus according to claim 1, wherein the pressurizing unit generates a flow in a certain direction in each of the common supply channel and the common recovery channel. The pressurizing means includes a first pressurizing means for generating a flow in a first direction in each of the common supply flow path and the common recovery flow path;
2. A second pressurizing unit that generates a flow in a second direction opposite to the first direction in the common supply flow path and the common recovery flow path. 4. The liquid ejection device according to claim 3. The switching means is
First switching means provided between the first pressurizing means and the recording element substrate;
Second switching means provided between the second pressurizing means and the recording element substrate;
The liquid ejection apparatus according to claim 4, further comprising:   6. The switching means according to claim 1, wherein the switching means is constituted by a valve connected to at least one of the common supply flow path and the common recovery flow path and controlled to be opened and closed by the control means. The liquid discharge apparatus according to any one of the above. A pressure adjusting mechanism connected to at least one of the common supply flow path and the common recovery flow path and positioned between the pressurizing means and the recording element substrate;
7. The liquid ejection apparatus according to claim 1, wherein the pressure adjustment mechanism performs liquid flow and blockage according to a pressure in the common supply flow path.   The pressure adjusting mechanism has a check valve structure that opens the valve body when the downstream side is depressurized and closes the valve body when pressurized, and controls the pressure after passing through the valve body within a certain range. The liquid discharge apparatus according to claim 7. The control means brings the switching means into a communicating state, and the pressure adjusting mechanism is forcibly brought into a communicating state, the liquid is pressurized by the pressurizing means, and the liquid is supplied to the common supply channel and the common recovery channel. After filling and recovering,
The supply channel, the discharge port, and the recovery channel are filled with liquid by closing the valve by the control unit and performing pressurization from the upstream side of the valve by the pressurization unit. The droplet discharge device according to claim 1.   10. The liquid droplet ejection apparatus according to claim 1, wherein the liquid for filling and recovering is different from the liquid for forming an image. 11. A recording element substrate having a discharge port for discharging a liquid;
A supply flow path for supplying a liquid to the recording element substrate;
A recovery flow path for recovering liquid from the recording element substrate;
A common supply channel for supplying liquid to the supply channel;
A common recovery channel for recovering liquid from the recovery channel;
Pressurizing means for applying pressure to the common supply channel and the common recovery channel;
Switching means for switching between communication and blocking of the common supply channel and the common recovery channel;
A method for controlling a liquid ejection apparatus comprising:
Filling the common supply channel and the common recovery channel with liquid by driving the pressurizing means in a state where the common supply channel and the common recovery channel are in communication with each other;
By pressurizing the liquid filled in the common supply channel and the common recovery channel with the pressurizing unit in a state where the common supply channel and the common recovery channel are blocked by the switching unit, the supply flow Filling the channel, the discharge port, and the recovery channel with liquid;
A control method for a liquid ejection apparatus, comprising: