JP2014004693A - Liquid discharge head and liquid discharge recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid discharge head capable of filling a liquid filter with liquid smoothly without applying particularly large negative pressure on a liquid supply chamber or without applying liquid on the liquid filter in advance even when the liquid filter is in a state of not containing liquid in the liquid discharge head.SOLUTION: The liquid discharge head comprises: a main liquid supply chamber communicating with a plurality of nozzle discharging liquid; and a sub liquid supply chamber communicating with the main liquid supply chamber. The sub liquid supply chamber is divided into a first liquid supply chamber in upstream side of liquid flow direction and a second liquid supply chamber in downstream side of liquid flow direction by a supply filter. A liquid introduction member generating larger capillary force than the supply filter is brought into contact with a surface of the supply filter located at the second liquid supply chamber side.

Description

  The present invention relates to a liquid discharge head that discharges liquid for recording and a liquid discharge recording apparatus using the liquid discharge head.

  2. Description of the Related Art In a liquid discharge recording apparatus that performs recording by discharging liquid from a liquid discharge head onto a recording medium (hereinafter, also simply referred to as a recording apparatus), a plurality of nozzles that discharge liquid are generally formed with high density. High-definition recording is performed using this liquid discharge head. By arranging a plurality of liquid discharge heads and supplying inks of different colors to the respective heads, color recording can be performed on a recording medium with a relatively inexpensive and small configuration. For this reason, liquid discharge recording apparatuses are used in various recording apparatuses such as printers, facsimiles, and copying machines regardless of whether they are for business use or home use.

  In the liquid discharge recording apparatus as described above, it is important to maintain the pressure acting on the liquid in the liquid discharge head at a predetermined negative pressure in order to stabilize the liquid discharge operation from the liquid discharge head. In recent years, it has been desired to further increase the recording speed of the liquid discharge recording apparatus, and as shown in Patent Document 1, a mode of controlling the negative pressure in the liquid discharge head has been proposed.

  In a liquid discharge head mounted on such a liquid discharge recording apparatus, it is necessary to dispose a filter in the liquid discharge head in order to remove foreign matters mixed in the liquid supplied to the nozzle. However, when a filter is provided, a pressure loss of the liquid flow in the filter occurs, which may be one of the causes that hinder the increase in recording speed. In particular, a filter of a liquid discharge head that requires high-definition recording quality is required to have high filtration accuracy corresponding to the resolution of the nozzle, so that pressure loss per unit area increases. Therefore, in the liquid discharge head disclosed in Patent Document 2, a large-area filter is disposed in the large-capacity liquid chamber of the head so that the liquid supply performance to the nozzle is suitable for the recording speed. And it has the structure which removes efficiently the bubble which remains in a filter part by providing a bypass channel.

JP 2006-326855 A JP 2007-168421 A

  However, in the liquid discharge recording apparatus disclosed in Patent Document 1, when ink is first injected from an initial state where there is no ink in the liquid discharge head, the ink that has reached the filter is easily affected by the surface tension of the ink. There is a problem that it cannot pass. Therefore, a method is adopted in which a high negative pressure is generated in the large-capacity liquid chamber of the head so that the ink passes through the filter. In this method, there is a problem that fine bubbles are generated when the ink passes through the filter, and when the bubbles enter the nozzle portion of the head, the original ejection of the nozzle is hindered.

  As another method, a liquid such as ink is applied in advance to the entire surface or a part of the large area filter, and when the ink reaches the filter, it is integrated with the pre-applied ink and passed through the filter. Is also considered. However, in this case, a process of applying a liquid such as ink to the filter is required, and if the storage state is long, a new problem such that the ink cannot pass through the filter due to drying of the applied liquid. Occurs.

  According to the present invention, even when the liquid filter in the liquid discharge head does not contain liquid, the liquid supply chamber is smoothly applied without applying a particularly large negative pressure to the liquid supply chamber or by applying liquid to the liquid filter in advance. An object is to provide a liquid discharge head capable of filling a liquid filter with a liquid.

  In order to achieve the above object, the present invention has the following configuration.

  That is, according to the first aspect of the present invention, a main liquid supply chamber communicating with a plurality of nozzles that discharge liquid, a sub liquid supply chamber communicating with the main liquid supply chamber, and the sub liquid supply chamber A supply filter that is divided into a first liquid supply chamber on the upstream side in the direction and a second liquid supply chamber on the downstream side in the liquid flow direction; and a surface that is located on the second liquid supply chamber side in the supply filter; And a liquid introducing member that generates a capillary force larger than that of the supply filter.

  According to a second aspect of the present invention, there is provided a liquid discharge recording apparatus comprising: a liquid discharge head that supplies a liquid containing a color material; and a transport unit that transports a recording medium to the liquid discharge head. The head includes a main liquid supply chamber that communicates with a plurality of nozzles that discharge liquid, a sub liquid supply chamber that communicates with the main liquid supply chamber, and a first liquid supply upstream of the sub liquid supply chamber in the liquid flow direction. A supply filter that is divided into a chamber and a second liquid supply chamber downstream in the liquid flow direction, and a capillary force that is in contact with a surface of the supply filter located on the second liquid supply chamber side and is larger than the supply filter And a liquid introducing member that generates the above-mentioned characteristics.

  According to the present invention, even when the liquid filter disposed in the liquid discharge head is in an initial state not including liquid, a particularly large negative pressure is applied to the common liquid chamber, or liquid is applied to the liquid filter in advance. It is possible to smoothly fill the liquid without the need to do so.

1 is a front view schematically showing a liquid discharge recording apparatus according to the present invention. (A) is a side view which shows the liquid discharge head which can apply this invention, (b) is a front view of the liquid discharge head shown to the same figure (a). It is the figure which showed typically the liquid supply system and recovery system from a liquid tank to a liquid discharge head. (A) is a front view for demonstrating the structural example of the liquid discharge head of this embodiment, (b) is the IV-IV sectional view taken on the line (a), (c) is the figure ( It is the III-III sectional view taken on the line of a). It is a VV line sectional view showing the behavior of the liquid before and after the supply filter provided in the liquid discharge head in this embodiment. It is a schematic diagram which shows the behavior of the liquid with respect to the supply filter provided in the liquid discharge head in this embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a front view schematically showing a liquid discharge recording apparatus (hereinafter also simply referred to as a recording apparatus) to which this embodiment can be applied. The recording apparatus 100 is connected to the host PC 110. Based on the recording information transmitted from the host PC 110, the recording apparatus 100 changes the color from four liquid ejection heads (hereinafter also simply referred to as heads) 22K, 22C, 22M, and 22Y to a recording medium (hereinafter also referred to as roll paper) P. Recording is performed by ejecting ink as a liquid containing a material. The four liquid discharge heads 22K, 22C, 22M, and 22Y are arranged along the conveyance direction (arrow A direction) of the recording medium P. The liquid discharge heads are parallel to each other in the order of a liquid discharge head 22K that discharges black ink in the transport direction, a liquid discharge head 22C for cyan ink, a liquid discharge head 22M for magenta ink, and a liquid discharge head 22Y for yellow ink. Has been placed.

  The liquid discharge heads 22K, 22C, 22M, and 22Y are so-called line heads, and nozzles are arranged at a predetermined density along a direction (width direction) that intersects the recording medium conveyance direction. The arrangement width of the nozzles (the arrangement range of the nozzles in the width direction) is equal to or larger than the maximum recording width of the recording medium used. When recording is performed by the recording apparatus, recording is performed by ejecting liquid from the nozzles by driving a heater provided in the liquid ejection head without moving each head.

  In the liquid discharge head, foreign matters such as dust and ink droplets adhere to the surfaces (hereinafter also referred to as discharge port surfaces) 22Ks, 22Cs, 22Ms, and 22Ys on which the discharge ports, which are nozzle openings, are formed with recording. As a result, the ejection state changes, which may affect recording. Therefore, the recovery unit 40 is incorporated in the recording apparatus 100 so that liquid can be stably discharged from the heads 22K, 22C, 22M, and 22Y. By regularly cleaning the discharge port surface by the recovery unit 40, the liquid discharge state from the nozzles of the liquid discharge heads 22K, 22C, 22M, and 22Y can be recovered to a good discharge state. The recovery unit 40 is used to remove liquid and fine bubbles from the discharge port surfaces 22Ks, 22Cs, 22Ms, and 22Ys of the four liquid discharge heads 22K, 22C, 22M, and 22Y during the cleaning operation. A cap 50 is provided. The cap 50 is provided independently for each liquid ejection head 22K, 22C, 22M, 22Y.

  The recording medium P is supplied from the roll paper supply unit 24 and is conveyed in the direction of arrow A by the conveying mechanism 26 incorporated in the recording apparatus 100. The transport mechanism 26 includes a transport belt 26a that transports while holding the roll paper P, a transport motor 26b that rotates the transport belt 26a, and a roller 26c that applies tension to the transport belt 26a. In the recording operation, when the roll paper P being conveyed reaches below the black liquid ejection head 22K, black ink is ejected from the liquid ejection head 22K based on the recording information sent from the host PC 110. Similarly, ink of each color is ejected in the order of the liquid ejection head 22C, the liquid ejection head 22M, and the liquid ejection head 22Y. As a result, color recording is formed on the roll paper P.

  In the present embodiment, an example in which the present invention is applied to a recording apparatus using a long liquid discharge head 22 extending over the entire width direction of the recording area of the recording paper P is shown. However, the present invention is also applicable to a so-called serial scan type recording apparatus that repeats recording scanning in the main scanning direction of the liquid ejection head and conveyance of a predetermined amount of recording paper in the sub-scanning direction intersecting the main scanning direction. can do.

  Next, the form of the liquid discharge head incorporated in the recording apparatus will be described with reference to FIG. FIG. 2A is a front view showing a liquid discharge head to which this embodiment can be applied, and FIG. 2B is a side view showing a four-part liquid discharge head. The recording apparatus to which this embodiment can be applied has four liquid discharge heads corresponding to the inks of the respective colors, and these liquid discharge heads are integrated with each nozzle row positioned precisely. (Hereinafter, the four-head configuration in this state is referred to as a combined head). In other words, the pitches between the nozzle rows, the nozzle row direction deviation, the nozzle row height deviation, and the parallelism between the nozzle rows of each liquid ejection head are combined so as to form a combined head within a specified accuracy. In the present embodiment, the four liquid discharge heads 22K, 22C, 22M, and 22Y are connected. The through holes formed at both ends of the base plates 22Kb, 22Cb, 22Mb, and 22Yb to which the discharge chips (not shown) on which the nozzle rows are formed are bonded are arranged on the same axis, and the two shafts 50 are penetrated. The assembly head is configured by fixing with the stopper 52. The nozzle rows 22Kn, 22Cn, 22Mn, and 22Yn of the respective liquid discharge heads are positioned with high accuracy with respect to each other by a separately prepared assembled head forming jig.

  FIG. 3 is a diagram schematically illustrating a liquid supply system and a recovery system from the liquid tank 28 to the liquid ejection head 22 in the recording apparatus of the present embodiment. Since each liquid ejection head has the same structure, only one liquid ejection head 22 will be described below.

  The recording apparatus 100 includes a liquid ejection head 22, a liquid tank 28 that is detachable from the recording apparatus main body, a liquid channel 40 that connects the liquid tank 28 and the liquid ejection head 22, and an air flow that communicates with the interior of the liquid ejection head 22. A passage 42 and a pump 42 connected to the air passage 41 are provided. When the pump 42 is driven to depressurize the air flow path 41 and the liquid discharge head 22, the liquid is supplied into the liquid discharge head 22 from the liquid tank 28 via the liquid flow path 40. A supply filter 18 is disposed in the liquid discharge head 22, and the liquid supplied to the liquid discharge head 22 flows into the main liquid supply chamber 26 through the supply filter 18. The liquid in the main liquid supply chamber 26 is eventually supplied into the nozzle and discharged, and details of the liquid supply system in the liquid discharge head will be described later.

  A liquid level detection sensor 21 is attached to a part of the main liquid supply chamber 26, and liquid supply is controlled based on the measurement result. That is, when it is detected that the liquid level in the main liquid supply chamber 26 is below a certain level, the pump 42 is driven to suck the liquid from the liquid tank 28. Then, when the sucked liquid is detected by the liquid level detection sensor 21 to be above a certain level, the pump 42 is stopped and the supply of the liquid is stopped.

  On the other hand, the pump 44 is used for a cleaning operation for each liquid discharge head to stably discharge liquid. The cleaning operation is an operation of removing fine bubbles and dust remaining in the nozzle and filling the nozzle with a fresh liquid suitable for recording. A recovery cap 43 (hereinafter also referred to as a cap) is provided at a position facing the surface (discharge port surface) on which the discharge port of the liquid discharge head is formed. The cap 43 is connected to a recovery channel 49, and a pump 44 is inserted into the recovery channel 49. A waste liquid tank 46 for storing waste liquid generated by the cleaning operation is connected to the downstream end of the recovery flow path 49.

  In the above configuration, at the time of cleaning, the cap 43 covers the discharge port surface of the liquid discharge head 22 so as to seal it. Thereafter, by driving the pump 44, the inside of the cap 43 and the recovery flow path 49 are depressurized, and residual bubbles and dust are sucked together with the liquid from the nozzle surface of the liquid discharge head 22. The sucked liquid or bubbles are guided to the waste liquid tank 46.

  FIG. 4A is a side view showing an example of the internal structure of the liquid ejection head of this embodiment. 4B is a cross-sectional view taken along the line IV-IV in FIG. 4A, and FIG. 4C is a cross-sectional view taken along the line III-III in FIG. For convenience of explanation, the liquid supply case cover is omitted in the side view of FIG.

  In each figure, a ceramic base plate 10 supports a heater substrate 11 made of silicon. The heater substrate 11 includes a plurality of electrothermal transducers (heaters or energy generators) as liquid discharge energy generating elements and a plurality of flow streams for constituting flow paths (nozzles) corresponding to these electrothermal transducers. A road wall is formed. The heater substrate 11 is also formed with a liquid chamber frame surrounding the common liquid supply chamber 12 communicating with each nozzle. A top plate 13 forming the common liquid chamber 12 is joined on the side wall of the nozzle and the liquid chamber frame formed in this manner. Therefore, the heater substrate 11 and the top plate 13 are laminated and bonded to the base plate 10 in an integrated state. Such lamination adhesion is performed with an adhesive having good thermal conductivity such as silver paste. A mounted PCB (electric wiring board) 14 is fixed to the base plate 10 with a double-sided tape (not shown) behind the heater substrate 11 in the base plate 10. Each discharge energy generating element on the heater substrate 11 and the PCB 14 are electrically connected by wire bonding corresponding to each wiring.

  A liquid supply member 15 is joined to the top surface of the top plate 13. The liquid supply member 15 includes a liquid supply case 16 (first case) and a liquid supply case cover 17 (second case). That is, the liquid supply case cover 17 closes the side surface of the liquid supply case 16 to form a liquid supply chamber and a liquid supply path, which will be described later. In the present embodiment, the liquid supply case 16 and the liquid supply case cover 17 are joined by a thermosetting adhesive. The liquid supply case 16 is provided with a supply filter 18 and a discharge filter 19. The supply filter 18 and the discharge filter 19 are arranged so that the liquid passage surface is substantially parallel to the direction of gravity.

  The supply filter 18 aims to remove foreign substances in the liquid supplied to the liquid supply member 15, and the discharge filter 19 aims to prevent foreign substances from entering from the outside of the liquid discharge head. Each filter is fixed to the liquid supply case 16 by heat welding. Further, a gas-liquid separation unit 20 is formed in a part of the liquid supply case 16 as a space for dividing the liquid flowing into the main liquid supply chamber 26 and the air. A liquid level detection sensor 21 is mounted on the gas-liquid separator 20 so as to protrude to the outside, and controls the amount of liquid in the main liquid supply chamber 26 as described above.

  Here, the configuration of the liquid supply chamber, the liquid supply path, and the like formed by joining the two parts of the liquid supply case 16 and the liquid supply case cover 17 will be described. A rectangular opening (hereinafter referred to as a liquid supply port) 27 is formed on the joint surface between the liquid supply case 16 and the top plate 13 and substantially parallel to the nozzle arrangement direction and over the width of the nozzle row. A main liquid supply chamber 26 is formed on the extension of the liquid supply port 27. That is, the main liquid supply chamber 26 is formed substantially parallel to the nozzle row and across the width of the nozzle row. Further, the liquid supply port 27 and the upper top surface form a main liquid supply chamber inclined portion 29 (hereinafter also simply referred to as an inclined portion 29) with the gas-liquid separation portion 20 as the uppermost portion over almost the entire area. . The inclined portion 29 is formed with two openings. One opening is the liquid communication portion 31 and the other opening is the gas-liquid separation portion 20.

  The gas-liquid separator 20 forms a part of the main liquid supply chamber 26 and has a depth larger than the other parts of the main liquid supply chamber 26. This is to enhance the effect of breaking bubbles that are mixed in the liquid in the liquid supply chamber, as will be described later. In the present embodiment, three stainless steel electrodes are mounted inside the gas-liquid separator 20, and are the upper limit detection electrode 23, the ground electrode 24, and the lower limit electrode 25 from the left side in the figure. The liquid level in the main liquid supply chamber 26 is maintained between the upper limit and the lower limit by energization between the ground electrode 24 and the upper limit detection electrode 23 and energization between the ground electrode 24 and the lower limit detection electrode 25. ing. In the liquid discharge head of this embodiment, the detection reliability can be improved by detecting the liquid level of the liquid that has undergone gas-liquid separation.

  There is an air communication part 30 on the extension of the gas-liquid separation part 20, and there is an air flow path (air chamber) 41 at the end. Further, the above-described discharge filter 19 is disposed and communicates with the discharge joint 33. The discharge filter 19 is made of a material having water repellency. For this reason, even if liquid flows into the air flow path 41 and ink adheres to the discharge filter 19, the capillary force of the filter portion can be reduced by the water repellency, and the ink can be easily removed. it can.

  On the other hand, a liquid supply path 37 is provided via a liquid communication portion 31 provided in the inclined portion 29. The liquid supply path 37 has a tubular shape extending from the liquid communication portion 31 to the vicinity of the supply filter 18 and is formed on substantially the same plane as the main liquid supply chamber 26. The supply filter 18 is also disposed on substantially the same plane as the main liquid supply chamber 26. The supply filter 18 is disposed so as to separate the sub liquid supply chamber into two chambers. Here, of the two separated chambers, the chamber communicating with the supply joint 32, that is, the chamber upstream in the liquid flow direction in the liquid discharge head is the first liquid supply chamber 34, and the chamber downstream in the liquid flow direction. A second liquid supply chamber 35 is provided. In addition, the supply filter 18 is disposed on the same plane as the main liquid supply chamber 26. Therefore, the first liquid supply chamber 34 and the second liquid supply chamber 35 adjacent to both surfaces of the supply filter 18 are also disposed on substantially the same plane as the main liquid supply chamber 26 and the nozzle arrangement surface 39. .

  The first liquid supply chamber 34 communicates with a liquid supply path 37 through an opening 27 above the supply filter 18. The top surface of the first liquid supply chamber 34 has a second liquid supply chamber inclined portion 38 (hereinafter simply referred to as a second inclined portion 38) having the opening 27 as the uppermost portion (the portion farthest from the supply filter). Is formed.

  Furthermore, the liquid introduction member 50 is disposed so as to abut on a surface on the second liquid supply chamber side (a surface on the downstream side) of both surfaces of the supply filter 18. Specifically, a rib is provided on the inner surface of the liquid supply case cover 17, that is, the surface facing the supply filter 18, and one end of the liquid introduction member 50 is held so as to be surrounded by the rib. The other end of the filter is in direct contact with one side surface of the supply filter 18. The liquid introduction member 50 is made of a material that generates a capillary force such as a porous body, and the capillary force is larger than the capillary force generated by the supply filter 18. For this reason, even when the liquid discharge head 22 is in an initial state in which no liquid is supplied therein, and the supply filter 18 does not contain ink, the liquid is smoothly passed through the supply filter 18. Can be supplied to the nozzle. That is, even when the supply filter 18 is in an initial state in which no liquid is contained, the liquid can smoothly pass through the supply filter 18 without applying a particularly large negative pressure in the liquid supply chamber.

  Next, the operation of the liquid ejection head and the liquid ejection apparatus in the present embodiment will be described along the flow of the liquid with reference to FIGS. 3 to 6.

  By the suction operation of the pump 42 shown in FIG. 3, the air in the liquid discharge head 22 is sucked and discharged through the discharge joint 33 shown in FIG. 4, and the pressure in the liquid discharge head 22 reaches a predetermined negative pressure. As a result, the liquid is supplied from the liquid tank 28 to the first liquid supply chamber 34 through the supply joint 32 of the liquid discharge head 22. Here, the flow of the liquid before and after the supply filter 18 will be described with reference to FIGS. 5 is a cross-sectional view taken along line VV in FIG. 4A, and in the figure, the B direction indicates the gravitational direction (vertical direction). FIG. 6 is an enlarged schematic view showing a part of FIG.

  In the conventional liquid discharge head, as schematically shown in FIG. 6A, the liquid filling the first liquid supply chamber 34 is in a state where a film is stretched on the mesh of the supply filter 18 by surface tension. In order to pass the liquid filling the first liquid supply chamber 34 to the opposite side of the supply filter 18, that is, to the second liquid supply chamber 35, a negative pressure equal to or higher than the surface tension is applied to the main liquid supply chamber 26. Must be generated. Moreover, since the flow velocity at the time of passing through the supply filter 18 is increased, there is a problem that fine bubbles are easily generated.

  On the other hand, in the liquid discharge head according to the present embodiment, the liquid introduction member 50 is in contact with the surface of the supply filter 18 on the second liquid supply chamber 35 side as shown in FIG. For this reason, the liquid does not stretch in the portion where the supply filter 18 and the liquid introduction member 50 are in contact with each other, and the capillary force of the liquid introduction member 50 can be obtained without generating a high negative pressure in the main liquid supply chamber 26. Thus, the liquid is smoothly sucked out to the second liquid supply chamber 35 side.

  Next, a process in which the liquid passes through the supply filter 18 will be described with reference to FIG. FIG. 5A shows an initial state where the liquid has not yet reached the first liquid supply chamber 34. Next, the liquid begins to enter the first liquid supply chamber 34, but the state where the liquid introduction member 50 has not yet reached the position where it abuts against the supply filter 18 is shown in FIG. At this time, the supply filter 18 is still covered with a film due to the surface tension of the liquid, and the liquid cannot pass through the supply filter 18. FIG. 5C shows a state in which the liquid level exceeds the contact position between the liquid introduction member 50 and the supply filter 18. In this state, the liquid passes through the supply filter 18 by the capillary force of the liquid introduction member 50 and is sucked out to the liquid introduction member 50 side. FIG. 5D shows a state in which the liquid level further rises, the liquid introduction member 50 is saturated with the liquid, and the liquid overflowing from the liquid introduction member 50 starts to accumulate on the second liquid supply chamber 35 side.

  Part of the liquid overflowing from the liquid introduction member 50 touches the surface of the supply filter 18 on the second liquid supply chamber 35 side, communicates with the liquid on the first liquid supply chamber 34 side of the supply filter 18, and passes to the supply filter 18. The formed film is destroyed. As a result, the liquid passes through the supply filter 18. Thereafter, destruction of the film in the supply filter 18 proceeds, and the region through which the liquid passes in the supply filter 18 is expanded as shown in FIGS. 5 (e) and 5 (f). Finally, liquid communication from the first liquid supply chamber 34 side to the second liquid supply chamber 35 side occurs over the entire area of the supply filter 18. As a result, the liquid filling process before and after the supply filter 18 is completed.

  In the liquid filling process described above, the air existing in the second liquid supply chamber 35 moves upward as the liquid flows in, but if the upper end portion of the supply filter 18 is exceeded, the second liquid supply chamber is inclined. It is led along the line 38 toward the liquid supply path 37. For this reason, when the liquid is supplied to the liquid supply path 37, the second liquid supply chamber 35 is filled with the liquid. The liquid supplied to the liquid supply path 37 then flows out to the main liquid supply chamber 26. The air in the main liquid supply chamber 26 moves upward as the liquid is supplied, and is eventually guided to the gas-liquid separator 20 along the main liquid supply chamber slope 29. When the liquid in which bubbles are mixed reaches the gas-liquid separator 20, the bubbles disappear because the thickness of the liquid chamber is increased. When the supply of liquid further proceeds, the liquid level detection sensor 21 installed in the gas-liquid separation unit 20 determines that the amount of liquid in the main liquid supply chamber 26 has reached the upper limit. At that time, the suction operation of the pump is stopped and the supply of liquid is stopped.

  Next, the flow of liquid in the liquid discharge head and the behavior of bubbles during the recording operation and the function of the liquid discharge head will be described. During recording, liquid droplets are ejected from the ejection surface using the liquid in the nozzle, but the internal pressure in the liquid ejection head decreases due to the ejection, and the liquid is replenished from the liquid tank by capillary action in the nozzle (hereinafter referred to as the following). Called refill). At this time, the refill performance is determined by the flow resistance until the liquid reaches the nozzle, such as a liquid flow path, a supply chamber, a supply filter, a liquid supply chamber, and a common liquid supply chamber from the liquid tank. In particular, the pressure loss of the supply filter 18 is dominant, but in the present embodiment, the supply filter 18 is arranged so as to be set to a large area, so that high-speed recording is possible. As can be seen from the section taken along the line III-III, the liquid is supplied substantially linearly from the main liquid supply chamber 26 to the liquid supply port 27, the common liquid supply chamber 12, and the nozzles over the entire nozzle row. Therefore, the liquid is smoothly supplied toward the nozzle.

  By the way, the liquid discharge head according to the present embodiment requires heat generation energy for liquid discharge. That is, the liquid is foamed by the thermal energy generated by the electrothermal transducer on the heater substrate, and the liquid is discharged from the nozzle using the foaming energy. For this reason, when the recording operation is continued for a long time, thermal energy is accumulated in the liquid, and the temperature of the liquid rises, and there is a possibility that the gas dissolved in the liquid accumulates in the liquid ejection head. Unless the bubbles in the liquid discharge head are removed, the liquid cannot be discharged properly. Therefore, with the configuration of the liquid discharge head of the present embodiment, bubbles generated in the liquid discharge head can be efficiently removed. Note that the discharge energy generating means for discharging the liquid is not limited to the configuration using the electrothermal transducer, and is arbitrary. For example, the configuration may be such that the liquid is discharged using a piezo element or the like.

  The liquid discharge head in the present embodiment is configured to communicate substantially linearly from the nozzles to the common liquid supply chamber 12 and the main liquid supply chamber 26 over the entire nozzle row. Therefore, even if air bubbles remain in the nozzle, the air bubbles are removed from the nozzle by the buoyancy of the air bubbles themselves and guided to the main liquid supply chamber 26. Further, the air bubbles guided to the main liquid supply chamber 26 move along the main liquid supply chamber inclination 29 and disappear when they reach the gas-liquid separator 20. Therefore, bubbles do not hinder the smooth supply of liquid. That is, a stable recording operation for a long time is possible.

  As described above, in the liquid discharge head, the main liquid supply chamber 26, the gas-liquid separator 20, the liquid supply path 37, the supply filter 18, the first liquid supply chamber 34a, and the second liquid supply chamber 34b are respectively connected to the nozzle array surface 39. Set on a substantially parallel plane. The main liquid supply chamber 26, the liquid supply path 37, the supply filter 18, and the gas-liquid separator 20 are arranged so as not to overlap each other. By having the configuration of the liquid discharge head in this way, the liquid supply speed to the nozzles in the liquid discharge head can be increased, bubbles in the liquid discharge head can be efficiently removed, and the liquid discharge head can be downsized. In particular, it is possible to improve the thinning. In the present embodiment, the suction mode is described as an example this time when the liquid discharge head is filled with the liquid by the suction operation by the pump, but the present invention is not limited to the suction mode. For example, it is possible to fill the discharge head with a liquid by a pressurizing operation by a pump.

  In the liquid discharge head described above, the liquid introduction member 50 is in contact with the surface of the supply filter 18 on the second liquid supply chamber 35 side, so that the liquid is discharged from the initial state where there is no liquid in the head. When filling the inside, the liquid can easily pass through the supply filter 18. Further, it is possible to suppress the generation of fine bubbles that are generated when the liquid passes through the supply filter 18 in the initial stage, and to stably fill the liquid.

  Therefore, according to the liquid discharge recording apparatus including the liquid discharge head according to the present invention, the liquid can be smoothly supplied from the liquid supply chamber to the nozzles of the liquid discharge head, and the recording speed can be increased. be able to.

(Other embodiments)
In the above embodiment, the case where the liquid introduction member 50 is provided in the intermediate portion of the supply filter 18 has been described as an example. However, the liquid introduction member 50 can be provided in a portion other than the intermediate portion of the supply filter 18. . For example, the liquid introduction member 50 may be provided so as to contact the upper part of the supply filter 18, and may further be provided so as to contact the lower part of the supply filter 18. However, if the upper end of the supply filter 18 is brought into contact, the time until the entire supply filter 18 can be in fluid communication or the time until the liquid filling process before and after the supply filter 18 is completed is completed. The shortest possible. On the other hand, when the liquid introducing member 50 is provided at the lower end of the supply filter 18, the time until the entire supply filter 18 becomes communicable is the longest.

  Further, in the above-described embodiment, the example in which the liquid introduction member 50 is provided by the rib 50 protruding from the liquid supply case cover 17 is shown, but the liquid introduction member 50 is not necessarily limited to the above embodiment. The liquid introduction member 50 may be fixed to the liquid supply case cover 17 with an adhesive or the like.

  As described above, the liquid introduction member 50 only needs to be formed of a material that can generate a capillary force higher than that of the supply filter 18. For example, an elastic member or the like can be used, and the material is not limited to a specific material.

  In addition, the case where an electrothermal transducer is used as an energy generating element that generates energy for discharging liquid from the liquid discharge head has been described as an example. However, as the energy generating element, other elements such as electromechanical conversion are used. It is also possible to use a body or the like.

12 Common liquid chamber 14 PCB
17 Liquid supply case cover 17a Rib 18 Supply filter 22 Liquid discharge head 26 Main liquid supply chamber 34 First liquid supply chamber 35 Second liquid supply chamber 37 Liquid supply path 39 Nozzle arrangement surface 50 Liquid introduction member

Claims (8)

A main liquid supply chamber communicating with a plurality of nozzles for discharging liquid;
A sub liquid supply chamber in communication with the main liquid supply chamber;
A supply filter that divides the sub liquid supply chamber into a first liquid supply chamber on the upstream side in the liquid flow direction and a second liquid supply chamber on the downstream side in the liquid flow direction;
A liquid introduction member that contacts a surface located on the second liquid supply chamber side in the supply filter and generates a capillary force larger than that of the supply filter;
A liquid discharge head comprising:   2. The liquid discharge head according to claim 1, wherein the liquid introduction member is in contact with an intermediate portion in a direction of gravity in a surface of the supply filter that is located on the second liquid supply chamber side.   2. The liquid discharge head according to claim 1, wherein the liquid introduction member is in contact with an upper portion in a direction of gravity in a surface of the supply filter that is positioned on the second liquid supply chamber side.   2. The liquid discharge head according to claim 1, wherein the liquid introduction member is in contact with a lower portion in a direction of gravity in a surface of the supply filter located on the second liquid supply chamber side.   The liquid discharge head according to claim 1, wherein the liquid introduction member is formed of a porous body.   The liquid discharge head according to claim 1, wherein the liquid introduction member is formed of an elastic member.   One end of the liquid introduction member is held by a rib projecting from the sub liquid supply chamber, and the other end of the liquid introduction member contacts a surface of the supply filter located on the second liquid supply chamber side. The liquid discharge head according to claim 1. A liquid discharge recording apparatus comprising: a liquid discharge head for containing a color material; and a transport unit for transporting a recording medium to the liquid discharge head,
The liquid discharge head is
A main liquid supply chamber communicating with a plurality of nozzles for discharging liquid;
A sub liquid supply chamber communicating with the main liquid supply chamber;
A supply filter that divides the sub liquid supply chamber into a first liquid supply chamber on the upstream side in the liquid flow direction and a second liquid supply chamber on the downstream side in the liquid flow direction;
A liquid introduction member that contacts a surface located on the second liquid supply chamber side in the supply filter and generates a capillary force larger than that of the supply filter;
A liquid discharge recording apparatus comprising:

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