JP2019034464A - Liquid ejection head and liquid ejection device - Google Patents

Abstract

To realize, with a simple passage structure, a structure that is able to easily eject pigment particles deposited in a liquid chamber of an ink head, without installation of a complicated passage or the like.SOLUTION: An ink head has a state of ink quiescence, a state of ejection of deposited ink by application of pressure and a state of ejection of deposited ink by suction, and comprises: an election unit 29 that ejects a liquid; and a liquid chamber 21 that supplies the liquid to the ejection unit, the liquid chamber including a structure in which a flow rate of the liquid flowing along a surface 21A where a component of the liquid may stay during non-ejection is higher than a flow rate at which the liquid flows along the other surface.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a liquid discharge head and a liquid discharge apparatus for discharging a liquid containing a sedimenting component, and more particularly to an ink jet recording head and an ink jet recording apparatus that discharge ink containing pigment particles as a liquid.

  Ink used for an ink jet recording head (hereinafter also simply referred to as a recording head) includes a dye ink using a dye as a colorant and a pigment ink using a pigment. Pigment inks have the advantage of better light resistance and weather resistance than dye inks. However, since the pigment ink is not a dissolution system but a dispersion system, precipitation of pigment particles is unavoidable. For example, when the recording head is left for a long time, the pigment particles settle and the layer where the ink is accumulated becomes a layer in which the pigment particle concentration is high and the color is excessively dark (hereinafter also referred to as sedimented ink). A phenomenon occurs in which the ink density is low and the color becomes a thin layer.

  Thus, for example, Patent Document 1 discloses a recording head including a liquid flow path that communicates a liquid introduction path and a liquid supply chamber, and the liquid flow path is located upstream of a filter that filters the flowing ink. And what is provided with the 1st and 2nd liquid chamber formed in the downstream is disclosed. Here, the first liquid chamber is relatively lower than the second liquid chamber in the vertical direction, and the vertical height of the second liquid chamber is lower than the height of the first liquid chamber. Yes. By adopting such a configuration, it is possible to prevent the pigment particles that have settled and stay on the discharge port side from which the liquid is discharged, and to prevent the occurrence of defective discharge and uneven density in the recorded image due to the inflow. It is supposed to be possible.

JP 2014-151539 A

  However, in the configuration of Patent Document 1, if pigment particles that have settled in the first liquid chamber accumulate, they may not be easily discharged. Further, since the flow path provided in the recording head is complicated and the flow path becomes long, the recording head is increased in size, and accordingly, the inkjet recording apparatus may be increased in size. In addition, when printing is performed at high speed, there is a possibility that the supply of ink used for recording cannot catch up.

  Accordingly, an object of the present invention is to realize a configuration capable of easily discharging pigment particles when they settle and stay with a simple flow path structure.

  A flow rate of a liquid flowing along another surface, which is a discharge unit that discharges the liquid, and a liquid chamber that supplies the liquid to the discharge unit, where the liquid component stays at the time of non-discharge And a liquid chamber including a higher structure.

  According to the present invention, it is possible to provide a liquid discharge head capable of easily discharging pigment particles when they settle and stay.

1 is a schematic configuration of a recording apparatus including a recording head as a liquid discharge head according to a first embodiment of the present invention. FIG. 2 is a schematic configuration diagram of an ink supply system in the recording apparatus of FIG. 1. It is sectional drawing of the ink tank in FIG. FIG. 3 is a cross-sectional view of the recording head in FIG. 2. It is explanatory drawing of the ink holding member in FIG. FIG. 5 is a schematic cross-sectional view taken along the line VI-VI in FIG. 4 for explaining the internal structure of the recording head according to the first embodiment of the invention. It is explanatory drawing of the ink supply system at the time of ink rest. (A)-(c) is explanatory drawing of the ink supply system at the time of the sedimentation ink discharge by discharge of a recording head. (A)-(c) is explanatory drawing of the ink supply system at the time of the sedimentation ink discharge by discharge of a recording head. (A)-(c) is explanatory drawing of the ink supply system at the time of sedimentation ink discharge by pressurization of a recording head. (A) And (b) is explanatory drawing of the ink supply system at the time of sedimentation ink discharge by pressurization of a recording head. (A)-(c) is explanatory drawing of the ink supply system at the time of the sedimentation ink discharge by the suction of a recording head. (A) And (b) is explanatory drawing of the ink supply system at the time of sedimentation ink discharge by the suction of a recording head. FIG. 6 is a schematic cross-sectional view taken along the line VI-VI in FIG. 4 for describing an internal structure of a recording head according to a second embodiment of the invention. FIG. 6 is a schematic cross-sectional view taken along the line VI-VI in FIG. 4 for describing the internal structure of a recording head according to a third embodiment of the invention.

Hereinafter, the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1A is a schematic perspective view for explaining a schematic configuration of an ink jet recording apparatus 100 according to an embodiment of a liquid ejection apparatus to which the present invention can be applied, and FIG. It is a block diagram of a system.

  An ink jet recording apparatus 100 (hereinafter also simply referred to as a recording apparatus) is provided with an ink jet recording head 20 (hereinafter also simply referred to as a recording head) as an embodiment of the liquid discharge head of the present invention in a detachable manner, for example. .

  The recording apparatus 100 of the present embodiment is a full-line type recording apparatus, and a plurality of liquid passages 9 (hereinafter also referred to as nozzles) having one end serving as a discharge port are arranged over a range corresponding to the entire width of the recording medium P. A recording head 20 having an ejection part is used. In order to perform color recording, four recording heads 20Y, 20M, 20C, and 20Bk that discharge liquid yellow (Y), magenta (M), cyan (C), and black (Bk) inks are used. Is used. Note that when there is no need to distinguish the recording heads of the respective colors, they are comprehensively referred to as “recording head 20”.

  The transport mechanism 110 can perform recording on the recording medium P by continuously transporting the recording medium P in the direction of the arrow F by the transport belt 110B and ejecting ink from the recording head 20 in the process. However, the configuration of the transport mechanism 110 is not limited thereto, and the recording medium P may be transported using a transport roller or the like.

  The recording apparatus 100 includes a recovery processing system 130. The recovery processing system 130 is used for recovery processing for maintaining a good ink ejection state in the recording head 20. In the recovery process, the cap 60 is opposed to or joined to the surface (discharge port forming surface) of the recording head 20 on which the discharge port is formed, and the ink in the recording head 20 is pressurized to enter the cap 60 from the discharge port. A pressure recovery operation for forcibly discharging can be included. Further, the recovery process may include a suction recovery operation in which the cap 60 is brought into close contact with the ejection port forming surface of the recording head 20 and ink is sucked into the cap 60 from the ejection port of the recording head 20. The recovery processing further includes a preliminary discharge operation for discharging ink that does not contribute to image recording into the cap 60 from the discharge port, and a wiping operation for wiping the discharge port surface of the recording head on which the discharge port is formed. You can also.

  A CPU (control unit) 101 of the recording apparatus 100 executes control processing of the operation of the recording apparatus 100, data processing, and the like. The ROM 102 stores programs such as those processing procedures, and the RAM 103 is used as a work area in these processes. The CPU 101 controls the recording head 20, the transport system 110, the ink supply system 120, and the recovery processing system 130 via the corresponding drivers 20A, 110A, 120A, and 130A. The CPU 101 records an image on the recording medium P by ejecting ink from the recording head 20 based on image data input from a host device 200 such as a host computer. The CPU 101 operates the recording head 20, the transport system 110, the ink supply system 120, and the recovery processing system 130, and will be described later “when the ink is stationary”, “discharge of precipitated ink by pressurization”, and “sedimentation by suction”. Ink discharge control is executed.

  2 is an explanatory diagram of the ink supply system 120 and the recovery processing system 130, FIG. 3 is an enlarged sectional view of the ink tank 30 in FIG. 2, and FIG. 4 is an enlarged sectional view of the recording head 20 in FIG. .

  Inside the ink tank 30, there are an ink chamber 31 for containing ink, a joint part 32 communicating with the ink chamber 31, a spring 33-1 for generating negative pressure inside the ink chamber 31, and the spring 33. -1 is connected to the pressure plate 33-2.

  The ink chamber 31 is a closed space in which only the joint portion 32 can communicate with the outside, and is formed using a flexible member. The ink tank 30 is detachable from the recording head 20 and is provided on the upper part of the recording head 20.

  The spring 33-1 urges the ink chamber 31 from the inside toward the outside so as to expand the internal space of the ink chamber 31 via the pressure plate 33-2. As a result, the spring 33-1 generates a predetermined negative pressure inside the ink chamber 31. The spring 33-1, the pressure plate 33-2, and the ink chamber 31 constitute a negative pressure generator. The joint portion 32 is provided with a non-woven filter 34.

  Each nozzle 9 of the discharge unit 29 is provided with a discharge energy generating element (not shown) for discharging the ink I introduced from the liquid chamber 21 from the discharge port 201. As the discharge energy generating element, an electrothermal conversion element, a piezoelectric element, or the like can be used. When the electrothermal conversion element is used, the ink is foamed by the heat generation, and the ink is ejected from the ejection port 201 using the foaming energy. Alternatively, when a piezo element is used, ink can be ejected by changing the volume in the nozzle by deformation or displacement in accordance with the application of voltage.

  In the liquid chamber 21, air is present together with the ink I. Accordingly, an ink storage portion 8 that stores the ink I and an air storage portion 7 that stores air are formed in the liquid chamber 21.

  An ink supply unit 22 for communicating with the ink tank 30 is provided in the upper part of the liquid chamber 21, and a filter member 23 is provided in the opening of the supply unit 22. In the case of this embodiment, the filter member 23 is formed of a SUS mesh. The mesh has a configuration in which metal fibers are woven, and the average width of the supply unit 22 is about 10 mm. Since the filter member 23 has fine eyes, foreign matter such as dust can be prevented from entering the recording head from the outside. The lower surface of the filter member 23 is in pressure contact with an ink holding member 24 that can hold ink. As shown in FIG. 5, a plurality of channels 24 </ b> A having a circular cross section are formed inside the ink holding member 24. The diameter of each flow path 24A is about 1.0 mm.

  In addition, an opening 25 that can be connected to a transfer part 51 that defines a flow path for transferring gas and / or liquid from the outside is provided in the upper part of the liquid chamber 21. 26 is provided. The opening 25 is configured so that ink or gas in the liquid chamber 21 can flow out and ink or gas outside the recording head 20 can flow in. Further, the opening 25 can be fed with ink and gas outside the recording head 20.

  The supply portion 22 of the recording head 20 and the joint portion 32 of the ink tank 30 are connected so that the filter member 23 on the recording head 20 side and the filter 34 on the ink tank 30 side are pressed against each other. Further, since the periphery of the connecting portion between the recording head 20 and the ink tank 30 is surrounded by a rubber elastic cap member 50, hermeticity is maintained. In this embodiment, the recording head 20 and the ink tank 30 are directly connected in this way, so that the ink supply path between them is formed extremely short.

  The transfer unit 51 has a three-way pipe structure, and a pipe part connected to the opening 25 of the recording head 20 and a pipe part communicating with the outside air via a valve 52 that can be opened and closed. And a pipe line portion communicating with the buffer chamber 54 through an openable / closable valve 53. A space having an internal volume of about 10 mL is defined in the buffer chamber 54, and this space is connected to a pump 55, and further communicated with the waste ink tank 56 via the pump 55. Further, the buffer chamber 54 is provided with an air release valve 57. The transfer unit 51 is a transfer unit that allows ink and / or gas to flow into or out of the recording head 20. In the present embodiment, a tube pump that can rotate forward and backward (that is, the direction of fluid flow can be changed) is used as the pump 55.

  The buffer chamber 54 and the cap 60 communicate with each other via a valve 61 that can be opened and closed. The cap 60 can be in close contact with the ejection port forming surface of the recording head 20. In the contact state, the valve 53 is closed, the valve 61 is opened, and the pump 55 is operated to bring the cap 60 into a negative pressure state, whereby ink is sucked and discharged from the discharge port 201 into the cap 60 (described above). Suction recovery operation). In addition, it is possible to perform a preliminary discharge operation in which ink that does not contribute to recording is discharged from the discharge port 201 into the cap 60 in a state where the cap 60 is in close contact with or opposed to the discharge port formation surface. Further, the valves 52 and 61 are closed, the valve 53 is opened, and the pump 55 is operated to bring the buffer chamber 54 and thus the liquid chamber 21 into a pressurized state, thereby forcibly supplying ink into the cap 60 from the discharge port 201. It is possible to perform a pressure recovery operation for discharging.

  The ink received in the cap 60 by the above recovery processing releases the close contact state of the cap 60, closes the valve 53, opens the valve 61, and operates the pump 55, thereby operating the buffer chamber 54 and the waste ink tank. 56 can be discharged.

  6 is a schematic cross-sectional view taken along the line VI-VI in FIG. 4 for explaining the internal structure of the recording head according to the first embodiment of the invention.

  The liquid chamber 21 is connected to a discharge portion 29 including a plurality of nozzles 9, and the liquid chamber 21 of the present embodiment has a structure in which the flow path is curved and gradually narrows as it approaches the connection portion with the discharge portion 29. ing. More specifically, the inner wall that defines the internal space of the liquid chamber 21 includes an inner wall portion 21A having a curved surface that protrudes outward in the vicinity of the connection portion, and an inner wall portion having a curved surface that is concave inward. 21B. The curved surface of the inner wall portion 21A is not curved with the flow path along it exceeding 90 degrees. In the present embodiment, the recording head 20 is used while being held by the recording apparatus 100 in a posture in which the plurality of nozzles 9 formed in the ejection unit 29 are positioned at the lowest position. Therefore, the flow path along the inner wall portion 21A that is curved in the liquid chamber 21 does not have a lower portion than the nozzle, and when the ink is at rest, it faces upward in the vertical direction of the surface formed by the inner wall portion 21A. The pigment particles are most likely to stay on the surface portion near the position A of the connecting portion. Further, the flow path at the connection portion between the liquid chamber 21 and the nozzle 9 is the narrowest.

  On the other hand, when ink is ejected from the ejection port 201 of the nozzle 9, the ink flows from the liquid chamber 21 toward the nozzle 9. When the flow along the surface of the inner wall portion 21A that defines the liquid chamber 21 at this time is considered, the flow velocity of the ink at the position A facing upward at the connection portion is higher than at other positions.

  As described above, the recording head 20 of the present embodiment includes the liquid chamber 21 having a simple flow path structure in which pigment particles do not easily settle and stay, and easily discharges the sediment even when sedimentation or retention occurs. It has the structure which can be. Next, the generation of the settled ink and the specific discharge operation based on the state of the recording apparatus will be described.

(When ink is stationary)
When the recording apparatus 100 is stopped, the ink is stationary, and the valves 52 and 53 are closed as shown in FIG. The flow path 24A of the ink holding member 24 is filled with ink. The liquid chamber 21 of the recording head 20 is in a predetermined negative pressure state, and the ink meniscus formed in the ejection port 201 is maintained. As shown in FIG. 7B, an ink meniscus is formed in the flow path 24A of the ink holding member 24, and forces Pt, Ph, Pk, and Pg act on the meniscus. The force Pt is a force that pulls the meniscus toward the ink tank 30 due to the negative pressure in the ink tank 30, and the force Ph is a force that pulls the meniscus into the recording head 20 due to the negative pressure in the recording head 20. The force Pk is a meniscus force that draws the ink toward the ink tank 30 due to the surface tension of the ink itself, and the force Pg is a force that causes the ink to move downward due to its own weight. When these forces are balanced, the meniscus formed in the ink holding member 24 is maintained, and the ink is kept stationary in the recording head 20. When the ink is stationary as described above, the pigment particles settle and the sedimented ink stays.

(Discharge of sedimented ink by ejection)
During the discharging operation of the settled ink by discharging, the valves 52 and 53 are closed as shown in FIG. In this state, the ink I in the liquid chamber 21 is consumed by discharging ink from the discharge port 201 as shown in FIG. 8A, and the pressure in the liquid chamber 21 is further reduced as shown in FIG. 8B. Is done. The negative pressure in the liquid chamber 21 thus increasing acts as a force in the direction of drawing the ink in the flow path 24A of the ink holding member 24 into the ink tank 30. When the negative pressure in the liquid chamber 21 increases to a predetermined level or more, the ink meniscus formed in the flow path 24A of the ink holding member 24 is broken, and the ink in the ink tank 30 as shown in FIG. Ink is supplied to the recording head 20. At this time, the settled ink collected in the lower part of the liquid chamber 21, that is, in the vicinity of the connection part with the discharge part 29, moves to the nozzle 9 formed in the discharge part 29 and is discharged together with the ink flow. Then, when the negative pressure in the liquid chamber 21 is reduced by such ink supply, the ink supply is stopped as shown in FIG.

  The sedimentation ink discharging operation described above may be performed in conjunction with the preliminary ejection operation. However, if the ink stationary time is short and the degree of sedimentation of the pigment particles or the density change associated therewith is not a problem, the recording operation is performed. It may be performed together. In any case, in the recording head 20 of the present embodiment, the staying settled ink can be effectively discharged.

(Discharge of precipitated ink by pressurization)
In order to pressurize the inside of the recording head 20 and discharge the settled ink, the negative pressure in the liquid chamber 21 is eliminated by opening the valve 52 and allowing outside air to flow into the recording head 20 as shown in FIG. To do. Next, as shown in FIG. 9B, the valves 52 and 53 are closed, and the pump 55 is rotated in one direction, whereby air is sent into the buffer chamber 54 and pressurized. As shown in FIG. 9C, the valve 53 is opened to pressurize the liquid chamber 21 in the recording head 20 with the pressurized air in the buffer chamber 54. At this time, if ink is mixed in the buffer chamber 54 or the transfer unit 51, the ink and / or gas flows into the recording head 20.

  By pressurizing the inside of the liquid chamber 21 in this way, the ink in the flow path 24A of the ink holding member 24 moves to the ink tank 30 side as shown in FIG. 10A, while as shown in FIG. 10B. In addition, the ink in the liquid chamber 21 is discharged from the nozzle 9.

  That is, when the inside of the liquid chamber 21 is pressurized, the meniscus in the flow path 24A of the ink holding member 24 moves backward toward the ink tank 30 as shown in FIG. When the meniscus reaches the filter member 23, the ink I is pushed out from the ejection port 201 as shown in FIG. Specifically, as shown in FIG. 11A, since the meniscus force Pk in the ink holding member 24 is small, the meniscus moves backward toward the ink tank 30 as the liquid chamber 21 is pressurized. As shown in FIG. 8B, when all the ink in the flow path 24 </ b> A is returned into the ink tank 30, a meniscus is formed in the filter member 23. Since the meniscus force Pn of the discharge port 201 is smaller than the meniscus force Pf of the filter member 23, the ink in the liquid chamber 21 is discharged from the discharge port 201.

  More specifically, the pressure in the liquid chamber 21 is increased to the pressure Pc. When the pressure Pc exceeds the meniscus force Pk, the meniscus of the ink holding member 24 moves to the ink tank 30 side, and when it reaches the filter member 23 having the meniscus force Pf, the meniscus does not move any more. Therefore, the ink I can be discharged from the ejection port 201 with the pressurization without pushing the air in the recording head 20 into the ink tank 30. At this time, the settled ink accumulated in the lower part of the ink chamber 31 moves to the nozzle 9 together with the ink flow and is discharged from the ejection port 201. The discharge of the precipitated ink by pressurization is more powerful than the discharge by the above-described discharge operation, and the precipitated ink can be discharged more effectively.

  After the discharge port forming surface is wetted by the discharged ink in this way, or while performing the ink discharge operation from the discharge port 201, the plate-like cleaning member 58 is used as shown in FIG. Wiping the discharge port forming surface. Thereby, the settled ink collected in the vicinity of the nozzle can be wiped off. The cleaning member 58 is made of, for example, urethane rubber. By sliding at least one of the cleaning member 58 and the recording head 20 in the left-right direction (relative movement) in FIG. The cleaning can be performed.

  After wiping by the cleaning member 58, the pump 55 is rotated in the reverse direction, a negative pressure is introduced into the recording head 20, and the liquid and / or gas is allowed to flow out of the recording head 20, so that the state shown in FIG. Can be returned to.

(Discharge of sedimented ink by suction)
When discharging the sedimented ink by applying a suction force to the recording head 20, first, the valve 52 is opened as shown in FIG. Eliminate the negative pressure inside. Next, as shown in FIG. 12B, the valves 52 and 53 and the valve 61 are closed, and the pump 55 is rotated in one direction, so that the air in the buffer chamber 54 is removed, thereby reducing the inside of the buffer chamber 54. Pressure. Further, as shown in FIG. 12C, the cap 60 is brought into contact with the recording head 20 and the valve 61 is opened, whereby the buffer chamber 54 and the cap 60 are communicated with each other, and the inside of the cap 60 is set to a negative pressure. Ink flows from the recording head 20 in accordance with the negative pressure in the cap 60 in contact therewith. At this time, the settled ink accumulated in the lower part of the liquid chamber 21 moves to the nozzle 9 and is discharged together with the ink flow. At this time, when the negative pressure in the liquid chamber 21 increases to a predetermined level or more, the ink meniscus formed in the flow path 24A of the ink holding member 24 is broken, and the ink tank 30 as shown in FIG. The ink inside is supplied to the recording head 20. The above-described discharge by pressurization causes the recording head 20 and the ink tank 30 to communicate with each other and there is a limit to pressurization. Therefore, more ink is discharged by suction, and the precipitated ink is discharged more strongly. Can do.

  After discharging the ink by such suction for a predetermined time, the pressure in the cap 60 is returned to the atmospheric pressure by opening the air release valve 57 communicating with the buffer chamber 54 as shown in FIG. Ink flow from the recording head 20 to the cap 60 can be stopped. Thereafter, the cap 60 that has returned to atmospheric pressure is separated from the recording head 20.

  Further, when the discharge port forming surface is wetted by the ink sucked by the cap 60, the discharge port forming surface is wiped using the plate-shaped cleaning member 58, as in the case where the ink is discharged by pressurization. Thereby, the settled ink etc. which collected in the nozzle vicinity can be wiped off.

(Second Embodiment)
In the above, the basic structure of the ink jet recording apparatus 100 and the structure of the recording head and the discharge operation of the precipitated ink according to the first embodiment have been exemplified. However, various structures can be adopted for the liquid chamber 21 of the recording head 20 as long as it conforms to the technical idea of the present invention.

  FIG. 14 is a cross-sectional view of the liquid chamber 21 shown in FIG. 4 for explaining a recording head according to the second embodiment of the present invention. Similarly to the first embodiment, the liquid chamber 21 and the discharge unit 29 are connected, and the flow path in the liquid chamber 21 is the lowest in the position A of the connection portion and is most narrowed.

  In the present embodiment, the inner wall portion 21A of the liquid chamber 21 has a curved surface that curves as it approaches the position A of the connecting portion, as described above. On the other hand, the inner wall portion 21B has a flat surface that is close to the connecting portion while being generally parallel to the outer wall, and a surface that narrows the flow path together with the curved surface. For this reason, in the vicinity of the connection portion between the liquid chamber 21 and the discharge section 29, the flow passage cross-sectional area in the liquid chamber 21 is rapidly reduced and the flow velocity is increased, so that the ink and thus the precipitated ink further flows into the nozzle 9 side. It becomes easy.

(Third embodiment)
FIG. 15 is a cross-sectional view of the liquid chamber 21 shown in FIG. 4 for explaining a recording head according to the third embodiment of the present invention. Similarly to the first and second embodiments, the liquid chamber 21 and the discharge section 29 are connected, and the flow path in the liquid chamber 21 is narrowed with the position A of the connection section at the lowest position.

  In the present embodiment, the inner wall portion 21A of the liquid chamber 21 has a flat inclined surface that is inclined toward the position A of the connecting portion, not a curved surface. On the other hand, the inner wall portion 21B has a flat surface that is close to the connecting portion while being generally parallel to the outer wall, and a surface that narrows the flow path together with the inclined surface. Even with such a structure, the highest flow velocity can be obtained at the position A, so that the ink and thus the settled ink can easily flow into the nozzle 9 side faster.

(Fourth embodiment)
(Adjustment by surface roughness)
In the above, the internal structure of the liquid chamber has been devised so that the flow velocity of the portion where the pigment particles are likely to stay (the connection portion with the discharge portion) is increased. However, it is also possible to adopt the following configuration instead of or together with it.

  The flow rate of the ink in the liquid chamber also changes depending on the surface roughness of the wall surface with which the liquid comes into contact. Therefore, the flow velocity may be adjusted by adjusting the surface roughness. For example, assuming that the arithmetic average roughness (Ra) of the wall surface of the portion where pigment particles are likely to stay is a mirror finish of about 0.4, and the other portion has an arithmetic average roughness (Ra) of about 1.6. In addition, it is possible to increase the ink flow rate in a portion where pigment particles are likely to stay.

(Other)
The present invention is not limited to the above-described embodiment and the modifications described in various places, and appropriate modifications, corrections, substitutions, and the like are possible.

  For example, in each of the embodiments described above, pigment particles are likely to stay in the connection portion with the discharge portion of the inner wall portion of the liquid chamber, but if other surface portions of the inner wall portion are likely to stay, The configuration as described above can also be adopted as appropriate for this portion.

  Further, for example, in the above-described embodiment, the three configurations of discharging the sedimented ink, one by ejection, one by pressurization inside the recording head, and one that performs suction from the recording head have been exemplified. However, not all of them may be executable, and any one or two of them may be executable. However, as described above, the force for discharging the settled ink increases in the order of discharge, pressurization of the printhead, and suction from the printhead. Therefore, when the three are provided as in the above example, it is advantageous because the discharge operation can be selectively activated according to the degree of sedimentation of the pigment particles. Since the sedimentation of the pigment particles increases as the ink stationary time increases, the determination of the degree of sedimentation can be made based on the time.

  In each of the above embodiments, the case where the present invention is applied to a so-called line head type recording head applied to a line printer type ink jet recording apparatus has been described. However, it goes without saying that the present invention can also be applied to a recording head applied to an ink jet recording apparatus in the form of a serial printer.

  Further, in each of the above embodiments, the ink jet recording head and the ink jet recording apparatus are exemplified as the liquid discharge head and the liquid discharge apparatus. However, the present invention can be widely applied to a liquid discharge head and a liquid discharge apparatus that discharge liquid other than ink as long as it discharges a liquid containing a component that causes sedimentation.

20 Recording head (liquid ejection head)
DESCRIPTION OF SYMBOLS 21 Liquid chamber 22 Ink supply part 23 Filter member 24 Ink holding member 24A Flow path 25 Opening part 29 Discharge part 51 Transfer part 55 Pump 100 Inkjet recording device

Claims (6)

A discharge section for discharging liquid;
A liquid chamber that supplies liquid to the discharge unit, and includes a structure in which the flow velocity of the liquid flowing along the surface where the retention of the liquid component occurs during non-discharge is higher than the flow velocity flowing along the other surface Room,
A liquid discharge head comprising:   2. The liquid discharge head according to claim 1, wherein the surface on which the stagnation occurs is a surface closest to the discharge unit among surfaces facing upward in the liquid chamber in a posture during liquid discharge.   The liquid discharge head according to claim 2, wherein the liquid chamber is most narrowed at a connection portion between the liquid chamber and the discharge portion.   4. The surface of the liquid chamber connected to the discharge unit is curved as it approaches the discharge unit, or is inclined toward the discharge unit. 5. The liquid discharge head according to claim 1.   5. The liquid discharge head according to claim 1, wherein a surface on which the stay occurs has the smallest surface roughness among the surfaces in the liquid chamber. A liquid discharge head according to any one of claims 1 to 5,
Recovery means for discharging the liquid from the discharge section by pressurization from the inside of the liquid discharge head or suction from the outside of the liquid discharge head;
A liquid ejecting apparatus comprising:

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