Liquid ejection head

A page-wide type liquid ejection head includes a plurality of recording element substrates, each having an ejection port array including a plurality of ejection ports, each ejection port communicating with a pressure chamber including therein a recording element, and a liquid supply path for supplying a liquid to the pressure chamber. The liquid ejection head also includes a flow path member mounting the recording element substrates arranged thereon. The flow path member includes common supply flow paths and individual supply flow paths that connect the liquid supply path to the common supply flow paths, and the individual supply flow paths include portions running obliquely to the direction orthogonal to the longitudinal direction of the liquid ejection head.

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to a liquid ejection head.

Description of the Related Art

A liquid ejection head that ejects a liquid such as ink in response to a drive signal for image recording or the like includes an energy generating element that generates energy for liquid ejection. For example, there is a liquid ejection head (inkjet recording head) that applies a voltage pulse in accordance with recorded data, to each of a plurality of energy generating elements (heating resistors as an example), and ejects liquid ink by using thermal energy which is generated. Liquid ejection heads like this are capable of high-resolution and high-speed image formation, and therefore are widely used. In particular, a liquid ejection apparatus including a full-line type (page-wide type) liquid ejection head having a length corresponding to a width of a recording medium, with a plurality of energy generating elements arranged with high density throughout a substantially entire length thereof is capable of higher speed recording, and has become widespread rapidly in recent years. Many long liquid ejection heads like this are each constructed by a plurality of chips (recording element substrates) being arranged along a width direction of a recording medium with a manufacturing yield taken into consideration, and the respective chips are small. On a support member on which a plurality of chips are mounted, a plurality of liquid supply holes (communication ports) for supplying liquids to the respective chips need to be formed at very narrow intervals with high precision along an arrangement direction of the chips. Therefore, a plurality of flow paths for supplying liquids to the plurality of liquid supply holes from liquid retaining members such as a liquid tank are constructed to transition from parts where the plurality of flow paths are disposed at relatively large intervals to parts where the plurality of flow paths are disposed at relatively small intervals. Japanese Patent No. 4495762 discloses a full-line type liquid ejection head in which widths and intervals of flow paths become narrower stepwise from a support member to respective chips.

The flow paths which supply liquids to the respective chips in Japanese Patent No. 4495762 are formed substantially perpendicularly to the arrangement direction of the chips, and a shortest distance between the adjacent flow paths is determined by a position in the arrangement direction of the chips. In the structure in which liquids of different kinds (for example, different colors) are supplied to the respective chips, joint portions of the chips, substrates and the like need to be sealed at each flow path so that different kinds of liquids do not mix with one another. However, in the structure in which a large number of flow paths are formed in a narrow region as in Japanese Patent No. 4495762, seal regions among the flow paths are so narrow that sealing with high reliability for each of the flow paths is difficult.

SUMMARY OF THE INVENTION

An object of the present disclosure is to provide a page-wide type liquid ejection head that has high reliability of seal between adjacent flow paths and can perform high-quality liquid ejection even when the number of flow paths that supply liquids to recording element substrates is large.

A liquid ejection head of the present disclosure is a page-wide type liquid ejection head, including: a plurality of recording element substrates each having an ejection port array including a plurality of ejection ports for ejecting a liquid, each ejection port communicating with a pressure chamber including therein a recording element that generates energy for ejecting a liquid, and a liquid supply path that supplies a liquid to the pressure chamber, and a flow path member on which the plurality of recording element substrates are arranged, wherein the flow path member includes a plurality of common supply flow paths that are provided adjacently to each other as running along a longitudinal direction of the liquid ejection head for supplying a liquid to the plurality of recording element substrates, and a plurality of individual supply flow paths that connect the liquid supply path of each recording element substrate to the common supply flow paths, and the plurality of individual supply flow paths include portions running obliquely to a direction orthogonal to the longitudinal direction of the liquid ejection head, as viewed from an ejection port array surface.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the present disclosure will be described with use of the drawings. However, the following description does not limit the range of the present disclosure. As an example, a thermal type that ejects a liquid by generating air bubbles by heating elements is adopted in the following embodiments, but the present disclosure can be also applied to liquid ejection heads in which a piezo type and various other liquid ejection types are adopted.

Note that the liquid ejection head of the present disclosure that ejects liquids such as ink is applicable to apparatuses such as a printer, a copying machine, a facsimile machine having a communication system, and a word processor having a printer unit, and further to industrial recording apparatuses that are multifunctionally combined with various processing apparatuses. For example, the liquid ejection head can also be used for applications such as biochip production, electronic circuit printing, semiconductor substrate production, and 3D printers.

The liquid ejection apparatuses of the following embodiments are inkjet recording apparatuses (recording apparatuses) each in a mode of circulating a liquid such as ink between a tank and the liquid ejection head, but may be in other modes. For example, the liquid ejection apparatuses may be each in a mode of providing two tanks at an upstream side and a downstream side of the liquid ejection head, and causing ink in pressure chambers to flow by passing the ink from one of the tanks to the other tank.

First Embodiment

(Explanation of Inkjet Recording Apparatus)

FIG. 1illustrates a schematic construction of the liquid ejection apparatus, in particular, an inkjet recording apparatus1000(hereinafter, also referred to as a recording apparatus) that ejects ink and performs recording. The recording apparatus1000includes a conveying section1that conveys a recording medium2, and a line type (page-wide type) liquid ejection head3that is disposed substantially orthogonally to a conveying direction of the recording medium. The recording apparatus1000is a line type recording apparatus that performs continuous recording by one-pass while continuously or intermittently conveying a plurality of recording media2. The recording medium2is not limited to a cut sheet, but may be a continuous roll sheet. Further, the present disclosure is also applicable to an intermediate transfer type apparatus that does not directly perform ejection to a medium such as a sheet from the liquid ejection head3, but ejects a liquid to an intermediate transfer member first to form an image on the transfer member, and thereafter transfers the image onto the medium such as a sheet. The liquid ejection head3is capable of full-color printing by CMYK (cyan, magenta, yellow and black) inks, and a liquid supply unit that is a supply path supplying a liquid to the liquid ejection head as described later, a main tank, and a buffer tank (FIG. 2) are fluidly connected to the liquid ejection head3. Further, an electric control unit that transmits electric power and an ejection control signal to the liquid ejection head3is electrically connected to the liquid ejection head3. A liquid route and an electric signal route in the liquid ejection head3will be described later.

(Explanation of First Circulation Route)

FIG. 2is a schematic view illustrating a first circulation route that is one mode of a circulation route which is applied to the recording apparatus of the present embodiment. A state where the liquid ejection head3is fluidly connected to a first circulation pump (high pressure side)1001, a first circulation pump (low pressure side)1002, a buffer tank1003and the like is illustrated. Note thatFIG. 2illustrates only a route in which an ink of one color of CMYK inks flows to simplify explanation, but in reality, circulation routes for four colors are provided in the liquid ejection head3and the recording apparatus main unit. The buffer tank1003as a sub tank which is connected to a main tank1006has an air communication hole (not illustrated) that allows an inside and an outside of the tank to communicate with each other, and is capable of discharging air bubbles in the ink to the outside. The buffer tank1003is also connected to a replenishing pump1005. The replenishing pump1005transfers a consumed amount of ink to the buffer tank1003from the main tank1006when the liquid is consumed in the liquid ejection head3by ejecting (discharging) the ink from the ejection ports of the liquid ejection head such as recording, and suction recovery by ink ejection.

The two circulation pumps1001and1002have a role of sucking a liquid from the liquid connection section111of the liquid ejection head3to cause the liquid to flow to the buffer tank1003. As the first circulation pump, a positive displacement pump having a quantative liquid delivering ability is preferable. Specifically, a tube pump, a gear pump, a diaphragm pump, a syringe pump and the like are cited, and a mode of ensuring a fixed flow rate by arranging an ordinary fixed low rate valve or a relief valve in a pump outlet, for example, may be adopted. A certain fixed amount of ink flows inside of each of a common supply flow path211and a common collection flow path212by the first circulation pump (high pressure side)1001and the first circulation pump (low pressure side)1002at a time of drive of the liquid ejection head3. The flow rate is preferably set at such a rate that temperature difference among respective recording element substrates10in the liquid ejection head3does not affect recorded image quality. In fact, when an excessively large flow rate is set, a negative pressure difference becomes so large in the respective recording element substrates10that image density unevenness occurs, due to the influence of the pressure loss in the flow paths in the liquid ejection unit300. Consequently, it is preferable to set the flow rate with a temperature difference and a negative pressure difference among the respective recording element substrates10taken into consideration.

A negative pressure control unit230is provided in a route between a second circulation pump1004and the liquid ejection unit300. This has a function of operating to keep a pressure at a downstream side (that is, a liquid ejection unit300side) from the negative pressure control unit230at a fixed pressure that is set in advance even when a flow rate of a circulation system varies due to a difference in duty (Duty) for performing recording. As two pressure adjusting mechanisms that construct the negative pressure control unit230, any mechanism that can control pressures downstream of the pressure adjusting mechanisms themselves to a variation in a fixed range or less with a desired set pressure as a center may be used. As an example, a mechanism similar to a so-called “pressure reducing regulator” can be used. When the pressure reducing regulator is used, it is preferable to pressurize an upstream side of the negative pressure control unit230via the liquid supply unit220by the second circulation pump1004as illustrated inFIG. 2. In this way, an influence of a water head on the liquid ejection head3, of the buffer tank1003can be suppressed, so that a degree of freedom of layout of the buffer tank1003in the recording apparatus1000can be increased. The second circulation pump1004may be any pump that has a lift pressure of a fixed pressure or more in a range of an ink circulation flow rate that is used at a time of drive of the liquid ejection head3, and a turbo type pump, a positive displacement pump and the like can be used. Specifically, a diaphragm pump or the like is adoptable. Further, instead of the second circulation pump1004, for example, a water head tank that is disposed with a certain fixed water head difference with respect to the negative pressure control unit230is adoptable.

As illustrated inFIG. 2, the negative pressure control unit230includes two pressure adjusting mechanisms to which different control pressures from each other are set respectively. Of the two negative pressure adjusting mechanisms, a relative high pressure set side (described as H inFIG. 2), and a relative low pressure set side (described as L inFIG. 2) are respectively connected to the common supply flow path211and the common collection flow path212in the liquid ejection unit300via an inside of the liquid supply unit220. In the liquid ejection unit300, an individual supply flow path213and an individual collection flow path214that communicate with the common supply flow path211, the common collection flow path212and the respective recording element substrates are provided. The individual flow paths213and214communicate with the common supply flow path211and the common collection flow path212, so that flows (arrows inFIG. 2) in which a part of liquid passes through internal flow paths of the recording element substrates10from the common supply flow path211to reach the common collection flow path212are generated. This is because the pressure adjusting mechanism H is connected to the common supply flow path211, and the pressure adjusting mechanism L is connected to the common collection flow path212respectively, and therefore a differential pressure occurs between the two common flow paths. A plurality of common supply flow paths211are provided adjacently to each other along a longitudinal direction of the liquid ejection head.

In this way, in the liquid ejection unit300, the flows in which a part of the liquid passes through the insides of the respective recording element substrates10are generated while the liquid is allowed to flow to pass through the insides of the common supply flow path211and the common collection flow path212respectively. Consequently, heat that is generated in the respective recording element substrates10can be discharged outside of the recording element substrates10by flows of the common supply flow path211and the common collection flow path212. Further, by the construction like this, when recording by the liquid ejection head3is performed, flows of ink can also be generated in ejection ports and pressure chambers that do not perform ejection, so that increase in viscosity of the ink in those sites can be suppressed. Further, the ink increased in viscosity and foreign matters in the ink can be discharged to the common collection flow path212. Consequently, the liquid ejection head3of the present embodiment is capable of recording at a high speed with high image quality.

(Explanation of Liquid Ejection Head Structure)

A structure of the liquid ejection head3according to the first embodiment will be described.FIGS. 3A and 3Bare perspective views of the liquid ejection head3according to the present embodiment. The liquid ejection head3is a line type liquid ejection head in which15of the recording element substrates10each capable of ejecting inks of four colors of CMYK are arranged rectilinearly (disposed in line). As illustrated inFIG. 3A, the liquid ejection head3includes signal input terminals91and electric power supply terminals92that are electrically connected to the respective recording element substrates10via flexible wiring boards40and an electric wiring board90. The signal input terminals91and the electric power supply terminals92are electrically connected to a control section of the recording apparatus1000, and respectively supply ejection drive signals and electric power necessary for ejection to the recording element substrates10. By concentrating wiring by electric circuits in the electric wiring board90, numbers of signal input terminals91and electric power supply terminals92can be decreased as compared with the number of recording element substrates10. Thereby, the number of electric connection portions that need to be detached can be small when the liquid ejection head3is assembled to the recording apparatus1000, or at a time of replacement of the liquid ejection head. As illustrated inFIG. 3B, liquid connection sections111that are provided at both end portions of the liquid ejection head3are connected to a liquid supply system of the recording apparatus1000. Thereby, inks of four colors of CMYK are supplied to the liquid ejection head3from the supply system of the recording apparatus1000, and the inks passing through the inside of the liquid ejection head3are collected into the supply system of the recording apparatus1000. In this way, the inks of the respective colors are capable of circulating via a route of the recording apparatus1000and a route of the liquid ejection head3.

FIG. 4illustrates an exploded perspective view of respective components or units constructing the liquid ejection head3. The liquid ejection unit300, the liquid supply unit220and the electric wiring board90are attached to an enclosure80. The liquid connection sections111(FIG. 2) are provided in the liquid supply unit220, and a filter221(FIG. 2) for each color that communicates with each opening of the liquid connection section111is provided inside the liquid supply unit220, to remove foreign matters in the ink which is supplied. The filters221for two colors are provided in each of the two liquid supply filters. The liquids that pass through the filter221are supplied to the negative pressure control unit230that is disposed on the liquid supply unit220correspondingly to the respective colors. The negative pressure control unit230is a unit including a pressure adjusting valve for each color, and generates the following operation by operations of a valve, a spring member and the like provided inside of each of the units. A change in pressure loss in the supply system (a supply system at an upstream side of the liquid ejection head3) of the recording apparatus1000, which occurs with a variation in the flow rate of the liquid is greatly attenuated, and a negative pressure change at a downstream side (a liquid ejection unit300side) from the negative pressure control unit can be stabilized to be within a certain fixed range. In the negative pressure control unit230of the respective colors, the two pressure adjusting valves are contained for each color as illustrated inFIG. 2. The two pressure adjusting valves are respectively set to different control pressures, a high pressure side communicates with the common supply flow path211in the liquid ejection unit300, whereas a low pressure side communicates with the common collection flow path212respectively via the liquid supply unit220.

The enclosure80is constructed by a liquid ejection unit supporting section81and an electric wiring board supporting section82, supports the liquid ejection unit300and the electric wiring board90, and ensures rigidity of the liquid ejection head3. The electric wiring board supporting section82is for supporting the electric wiring board90, and is fixed to the liquid ejection unit supporting section81by screwing. The liquid ejection unit supporting section81has a role of correcting a warp and deformation of the liquid ejection unit300, and ensuring relative positional precision of the plurality of recording element substrates10, and thereby suppresses streaks and unevenness in a recorded object. Consequently, the liquid ejection unit supporting section81preferably has sufficient rigidity, and as a material, a metal material such as a stainless steel (SUS) and an aluminum, or ceramics such as an alumina is preferable. In the liquid ejection unit supporting section81, openings83and84to which joint rubbers100are inserted are provided. The liquid supplied from the liquid supply unit220is guided to a third flow path member70constructing the liquid ejection unit300via the joint rubbers.

The liquid ejection unit300includes a plurality of ejection modules200and the flow path member210, and a cover member130is attached to a surface on a recording medium side of the liquid ejection unit300. Here, the cover member130is a member having a frame-shaped surface provided with an elongate opening131as illustrated inFIG. 4, and from the opening131, the recording element substrates10and sealing members110(FIGS. 8A and 8B) included in the ejection modules200are exposed. A frame portion around the opening131has a function as an abutting surface of a capping member that caps the liquid ejection head3at a recording standby time. Consequently, a closed space is preferably formed at a time of capping by applying an adhesive, a sealing material, a filler or the like along a perimeter of the opening131, and burying recesses and protrusions and gaps on the ejection port surfaces of the liquid ejection unit300.

Next, a structure of the flow path member210included in the liquid ejection unit300will be described. As illustrated inFIG. 4, the flow path member210is what is formed by stacking a first flow path member50, a second flow path member60and a third flow path member70. The flow path member210is a flow path member for distributing the liquid supplied from the liquid supply unit220to the respective ejection modules200, and returning the liquid which returns from the ejection modules200to the liquid supply unit220. The flow path member210is fixed to the liquid ejection unit supporting section81by screwing, and thereby a warp and deformation of the flow path member210are suppressed.

FIGS. 5A to 5Fare views that illustrates front surfaces and back surfaces of the respective flow path members of the first to third flow path members.FIG. 5Aillustrates a surface on a side where the ejection module200is mounted, of the first flow path member50, andFIG. 5Fillustrates a surface on a side abutting on the liquid ejection unit supporting section81, of the third flow path member70. The first flow path member50and the second flow path member60are joined so thatFIG. 5BandFIG. 5Cthat are abutment surfaces of the respective flow path members face each other, and the second flow path member and the third flow path member are joined so thatFIG. 5DandFIG. 5Ethat are abutment surfaces of the respective flow path members face each other. By joining the second flow path member60and the third flow path member70, eight common flow paths running in a longitudinal direction of the flow path members are formed by common flow channels62and71that are formed in the respective flow path members. Thereby, a set of the common supply flow path211and the common collection flow path212is formed for each color in the flow path member210(FIG. 6). Communication ports72of the third flow path member70communicate with the respective holes of the joint rubber100, and fluidly communicate with the liquid supply unit220. A plurality of communication ports61are formed on a bottom surface of the common flow channel62of the second flow path member60, and communicate with one end portion of the individual flow channels52of the first flow path member50. Communication ports51are formed on the other end portions of the individual flow channels52of the first flow path member50, and fluidly communicate with a plurality of ejection modules200via the communication ports51. The individual flow channels52enable flow paths to concentrate on a center side of the flow path member. The individual flow paths213and214are formed by grooves52that are formed on a surface on a recording element substrate side, of the flow path member50that is a plate member, and holes (the communication ports51) that communicate with the grooves52and open to a surface at an opposite side from the recording element substrate side, of the flow path member50.

The first to third flow path members preferably have corrosion resistance to a liquid, and are formed from a material with a low linear expansion coefficient. As the material, for example, a composite material (a resin material) formed by using an alumina, LCP (liquid crystal polymer), PPS (polyphenyl sulfide) or PSF (polysulfone) as a base material and adding an inorganic filler such as silica fine particles or fibers can be preferably used. As a forming method of the flow path member210, the three flow path members may be stacked and joined to one another, or may be joined by welding when the resin composite material is selected as the material.

Next, with use ofFIG. 6, a connection relation of the respective flow paths in the flow path member210will be described.FIG. 6is a transparent view of partially enlarged flow paths in the flow path member210which is formed by joining the first to third flow path members, as seen from a side of the surface on which the ejection modules200are mounted, of the first flow path member50. In the flow path member210, the common supply flow paths211(211a,211b,211cand211d) and the common collection flow paths212(212a,212b,212cand212d) which run in the longitudinal direction of the liquid ejection head3are provided for the respective colors. A plurality of individual supply flow paths213(213a,213b,213cand213d) which are formed by the individual flow channels52are connected to the common supply flow paths211of the respective colors via the communication ports61. Further, a plurality of individual collection flow paths214(214a,214b,214cand214d) which are formed by the individual flow channels52are connected to the common collection flow paths212of the respective colors via the communication ports61. By a flow path structure like this, the ink can be concentrated onto the recording element substrates10which are located in a central part of the flow path member from the respective common supply flow paths211via the individual supply flow paths213. Further, the ink can be collected into the respective common collection flow paths212from the recording element substrates10via the individual collection flow paths214.

FIG. 7is a view illustrating a section in line7-7inFIG. 6. As illustrated inFIG. 7, the respective individual collection flow paths (214a,214c) communicate with the ejection module200via the communication ports51.FIG. 7illustrates only the individual collection flow paths (214a,214c), but in other sections, the individual supply flow paths213and the ejection modules200communicate with each other as illustrated inFIG. 6. In a support member30and the recording element substrate10included in each of the ejection modules200, a flow path for supplying the ink from the first flow path member50to recording elements15(FIG. 9B) provided in the recording element substrate10is formed. Further, a flow path for collecting (returning) a part or all of the liquid which is supplied to the recording elements15and transfer the collected liquid to the first flow path member50is also formed. Here, the common supply flow paths211of the respective colors are connected to the negative pressure control units230(the high pressure side) of the corresponding colors via the liquid supply units220, and the common collection flow paths212are connected to the negative pressure control unit230(the low pressure side) via the liquid supply units220. By the negative pressure control unit230, a differential pressure (a pressure difference) is generated between the common supply flow path211and the common collection flow path212. Consequently, in the liquid ejection head of the present embodiment in which the respective flow paths are connected as illustrated inFIGS. 6 and 7, a flow flowing sequentially to the common supply flow path211, the individual supply flow path213, the recording element substrate10, the individual collection flow path214and the common collection flow path212is generated in each of the colors.

FIG. 8Aillustrates a perspective view of one ejection module200, andFIG. 8Billustrates an exploded view thereof. As a production method of the ejection module200, the recording element substrate10and the flexible wiring board40are firstly joined onto the support member30which is provided with liquid communication ports31in advance. Thereafter, a terminal16on the recording element substrate10and a terminal41on the flexible wiring board40are electrically connected by wire bonding, and thereafter, the wire bonding section (an electrically connecting section) is sealed by being covered with a sealer110. A terminal42at an opposite side from the recording element substrate10, of the flexible wiring board40is electrically connected to a connection terminal93(refer toFIG. 4) of the electric wiring board90. The support member30is a supporter that supports the recording element substrate10, and is also a flow path member that causes the recording element substrate10and the flow path member210to communicate with each other fluidly. The flow paths of the support member connect the liquid supply path18and the individual supply flow path213, and connect the liquid collection path19and the individual collection flow path214. The support member30preferably has a high flatness and can be joined to the recording element substrate with sufficiently high reliability. As the material, for example, an alumina, and a resin material are preferable.

(Explanation of Structure of Recording Element Substrate)

A structure of the recording element substrate10in the present embodiment will be described.FIG. 9Aillustrates a plan view of a surface on a side where the ejection ports13are formed, of the recording element substrate10of the liquid ejection head,FIG. 9Billustrates an enlarged view of a part shown by9B inFIG. 9A, andFIG. 9Cillustrates a bottom view ofFIG. 9A. As illustrated inFIG. 9A, ejection port arrays in four rows corresponding to the respective ink colors are formed in an ejection port formation member12of the recording element substrate10. Note that hereinafter, a direction in which the ejection port array where a plurality of ejection ports13are arranged extends will be referred to as an “ejection port array direction”.

As illustrated inFIG. 9B, in positions corresponding to the respective ejection ports13, the recording elements15which are heating elements for foaming the liquid by thermal energy are disposed. Pressure chambers23including the recording elements15therein are demarcated by partition walls22. The recording element15is electrically connected to a terminal16inFIG. 9Aby electric wiring (not illustrated) provided in the recording element substrate10. The recording element boils the liquid by generating heat based on a pulse signal that is input via the electric wiring board90(FIG. 4) and the flexible wiring board40(FIG. 8B) from the control circuit of the recording apparatus1000. The liquid is ejected from the ejection port13with a force of foaming by boiling. As illustrated inFIG. 9B, along each of the ejection port arrays, the liquid supply path18runs on one side, and the liquid collection path19runs on the other side respectively. The liquid supply path18and the liquid collection path19are flow paths provided in the recording element substrate10and running in the ejection port array direction, and communicate with the ejection ports13via supply ports17aand collection ports17brespectively.

As illustrated inFIG. 9CandFIG. 10, a sheet-shaped lid member20is stacked on a back surface of the surface where the ejection ports13are formed, of the recording element substrate10, and a plurality of openings21that communicate with the liquid supply path18and the liquid collection path19described later are provided in the lid member20. In the present embodiment, the three openings21are provided for each liquid supply path18, and the two openings21are provided for each liquid collection path19respectively in the lid member20. As illustrated inFIG. 9B, the respective openings21in the lid member20communicate with the plurality of communication ports51illustrated inFIG. 5A. As illustrated inFIG. 10, the lid member20has a function as a lid that forms part of walls of the liquid supply paths18and the liquid collection paths19formed in the substrate11of the recording element substrate10. The lid member20preferably is a member having sufficient corrosion resistance to the liquid, and from the viewpoint of prevention of color mixing, high precision is required of an opening shape and an opening position of the opening21. Therefore, it is preferable to use a photosensitive resin material and a silicon as the material of the lid member20, and provide the openings21by a photolithography process. In this way, the lid member converts pitches of the flow paths by the openings21, is desirably thin in thickness considering a pressure loss, and is desirably formed of a film-shaped member.

Next, a flow of the liquid in the recording element substrate10will be described.FIG. 10is a perspective view illustrating sections of the recording element substrate10and the lid member20in line10-10inFIG. 9A. The recording element substrate10has a structure in which the substrate11formed from Si and the ejection port formation member12formed from a photosensitive resin are stacked, and the lid member20is joined to a back surface of the substrate11. The recording elements15are formed on one surface side of the substrate11(FIG. 9B), and on a back surface side of the substrate11, grooves constructing the liquid supply paths18and the liquid collection paths19that run along the ejection port array are formed. The liquid supply path18and the liquid collection path19which are formed by the substrate11and the lid member20are respectively connected to the common supply flow path211and the common collection flow path212in the flow path member210, and a differential pressure is generated between the liquid supply path18and the liquid collection path19. When the liquid is ejected from the plurality of ejection ports13of the liquid ejection head3, in the ejection port that does not perform an ejection operation, the liquid in the liquid supply path18provided in the substrate11flows to the liquid collection path19via the supply port17a, the pressure chamber23and the collection port17bby the aforementioned differential pressure. The flow is illustrated by arrows C inFIG. 10. By this flow, in the ejection port13that stops recording and the pressure chamber23, ink with increased viscosity, bubbles, foreign matters and the like that are generated by evaporation from the ejection port13can be collected into the liquid collection path19. Further, increase in viscosity of the ink in the ejection port13and the pressure chamber23can be suppressed. The liquid that is collected into the liquid collection path19is collected to the communication ports51, the individual collection flow path214and the common collection flow path212in the flow path member210in this order through the openings21of the lid member20and the liquid communication ports31of the support member30(refer toFIG. 8B). Subsequently, the liquid is finally collected into the supply route of the recording apparatus1000.

That is, the liquid which is supplied to the liquid ejection head3from the recording apparatus main unit flows in the following order, and is supplied and collected. The liquid flows to the inside of the liquid ejection head3from the liquid connection section111of the liquid supply unit220first. Subsequently, the liquid is supplied to the joint rubber100, the communication ports72and the common flow channel71provided in the third flow path member, the common flow channel62and the communication ports61provided in the second flow path member, and the individual flow channel52and the communication ports51provided in the first flow path member in this order. Thereafter, the liquid is supplied to the pressure chamber23sequentially through the liquid communication ports31provided in the support member30, the openings21provided in the lid member, and the liquid supply paths18and the supply ports17aprovided in the substrate11. Of the liquids which are supplied to the pressure chambers23, the liquid which is not ejected from the ejection port13flows sequentially in the collection ports17band the liquid collection path19which are provided in the substrate11, the openings21provided in the lid member and the liquid communication ports31provided in the support member30. Thereafter, the liquid sequentially flows in the communication ports51and the individual flow channels52which are provided in the first flow path member, the communication ports61and the common flow channels62which are provided in the second flow path member, the common flow channels71and the communication ports72which are provided in the third flow path member70and the joint rubbers100. Subsequently, the liquid flows to outside of the liquid ejection head3from the liquid connection sections111provided in the liquid supply unit. In the mode of the first circulation route illustrated inFIG. 2, the liquid which flows in from the liquid connection section111is supplied to the joint rubber100after passing through the negative pressure control unit230.

Further, as illustrated inFIG. 2, all of the liquid that flows in from one end of the common supply flow path211of the liquid ejection unit300is not supplied to the pressure chambers23via the individual supply flow paths213a. Some parts of the liquid flow to the liquid supply unit220from the other end of the common supply flow path211without flowing into the individual supply flow paths213a. In this way, by including the route through which the liquid flows without passing through the recording element substrates10, a backflow of the circulation flow of the liquid can be suppressed, even in the case of having the recording element substrate10including flow paths which are very fine and having large flow path resistance as in the present embodiment. In this way, in the liquid ejection head of the present embodiment, increase in viscosity of the liquid in a vicinity of the pressure chamber and the ejection port can be suppressed, so that a deviation of the ejection direction and mis-ejection can be suppressed, as a result of which, recording with high image quality can be performed.

(Explanation of Positional Relation Among Recording Element Substrates)

FIG. 11is a plan view illustrating an adjacent portion of the recording element substrates in the two adjacent ejection modules by partially enlarging the adjacent portion. As illustrated inFIGS. 9A to 9C, in the present embodiment, the recording element substrate in a substantially parallelogram is used. As illustrated inFIG. 11, respective election port arrays14ato14din which the ejection ports13are arranged in the respective recording element substrates10are disposed so as to incline at fixed angles to a conveying direction (moving direction) of the recording medium. Thereby, in the ejection port arrays in the adjacent portion of the recording element substrates10, at least one ejection port overlaps in the conveying direction of the recording medium. InFIG. 11, two ejection ports on line D are in an overlapping relation with each other. By disposition like this, even when the position of the recording element substrate10deviates from a predetermined position to some degrees, a black streak and a white patch in the recorded image can be made less noticeable by drive control of the ejection ports which overlap each other. When a plurality of recording element substrates10are disposed rectilinearly (in line) instead of being arranged in a staggered fashion, a black streak and a white patch in the connecting portion of the recording element substrates10can be suppressed while increase in the length in the conveying direction of the recording medium, of the liquid ejection head3is suppressed by the structure inFIG. 11. Note that in the present embodiment, a main plane of the recording element substrate is in a parallelogram, but the present disclosure is not limited to this, and even when the recording element substrates in a rectangle, a trapezoid and other shapes are used, the structure of the present disclosure can be preferably applied.

As described above, in the present embodiment, the communication ports51of the first flow path member50are arranged in a staggered fashion correspondingly to the openings21for the respective liquids of the recording element substrate10. The respective openings21and the respective communication ports51are connected by the individual flow paths213and214. These individual flow paths213and214run in a direction that obliquely intersects the conveying direction of the recording medium. In detail, as seen from the ejection port array surface10aof the recording element substrate10, the individual flow paths213and214run in a direction that extends obliquely to the conveying direction (the moving direction) of the recording medium from portions connected to the liquid supply path18. Thereby, as compared with a case where the individual flow paths213and214run parallel with the conveying direction of the recording medium, a width of a seal region between the individual flow paths213and214can be ensured to be wide. As a result, the individual flow paths can be formed independently, and it is possible to form the flow paths in which the liquid flowing in the adjacent flow paths does not flow, and mixing of liquids of different kinds (different colors) is suppressed. Concerning the width of the seal region between the individual flow paths, comparison of the conventional structure and the present embodiment is illustrated inFIGS. 12A to 12D.FIG. 12Ais a plan view illustrating the conventional structure in which the individual flow paths213and214run substantially parallel to the conveying direction of the recording medium, andFIG. 12Cis a sectional view taken along line12C-12C inFIG. 12A. For convenience, the same reference signs as in the present disclosure are assigned. In the case of this structure, a space between the adjacent individual flow paths, that is, a joint margin of the first flow path member50is “a”.FIG. 12Bis a plan view illustrating a structure of the present embodiment in which the individual flow paths213and214run obliquely by an angle θ (0°<θ<90°) to the conveying direction of the recording medium, and is a view of a12B portion inFIG. 6by enlarging the12B portion.FIG. 12Dis a sectional view taken along line12D-12D inFIG. 12B. In the case of the structure, a space between the adjacent individual flow paths, that is, a joint margin of the first flow path member is “b”. As is obvious fromFIGS. 12A to 12D, the joint margin “b” of the present embodiment can be ensured to be larger than the joint margin “a” of the conventional configuration, so that reliability of sealing of the respective flow paths is high, and possibility of a trouble such as mixing of liquids (color mixing) and a leakage can be reduced.

Another effect of the present embodiment in which the individual flow paths213and214run in the direction to intersect the conveying direction of the recording medium obliquely will be described as follows.FIG. 13is a view illustrating a positional relation of the liquid communication ports31of the support member30, the liquid supply paths18and the liquid collection paths19of the recording element substrate10. The liquid communication ports31are formed in positions that allow the liquid communication ports31to communicate with the communication ports51of the first flow path member50. The liquid which is supplied from the liquid communication port31is supplied to the liquid supply path18through the opening21formed in the lid member20of the recording element substrate10, and a part of the liquid which is not ejected flows into the liquid collection path19. Further, the liquid which flows into the liquid collection path19reaches the individual collection flow path via the opening21, the liquid communication port31and the communication port51. Here, the liquid flows into the liquid supply path18with the openings21as inlets for liquid inflow, and the liquid flowing in is supplied to the respective ejection ports while flowing in the ejection port array direction. At this time, the liquid absorbs heat from the recording element substrate10while flowing, so that a temperature of the liquid gradually increases. As a result, a temperature distribution of the liquid occurs along the ejection port array direction, and unevenness of the ejection amount is likely to be caused in accordance with the temperature characteristics of the liquid. Therefore, it is preferable to determine the positions where the openings21are disposed, with the temperature distribution and the like taken into consideration. For example, in order to reduce density unevenness in the joint portion of the recording element substrates10, it is effective to shorten the distance in which the liquid flows to the end portion, and reduce the temperature increase of the liquid by disposing the openings21of the liquid supply paths18at the end portions of the recording element substrate10. If the individual flow paths are disposed obliquely as in the present embodiment, even when the liquid supply path and the liquid collection path are provided adjacently at a narrow pitch, the joint margin between the individual flow paths can be ensured while the openings21are disposed concentratedly at the end portions of the recording element substrate10. Thereby, unevenness in the joint portion between the adjacent recording element substrates can be reduced.

In the present embodiment, the example is shown in which the three openings21are provided in the liquid supply path18and the two openings21are provided in the liquid collection path19, but the present invention is not limited to this. For example, as illustrated inFIGS. 14 and 15, a structure in which the two openings21are provided in each of the liquid supply paths18, and the two openings21are provided in each of the liquid collection paths19may be adopted. Though not illustrated inFIG. 15, the communication port51is provided in a position projected to overlap the opening21, and the opening21communicates with the communication port51. At this time, it is preferable that the individual supply flow paths213of the respective liquids are located outside from the individual collection flow paths214in which the same liquids flow, because the effect of suppressing unevenness is large.

Second Embodiment

A second embodiment of the present disclosure will be described hereinafter.

FIG. 16is an enlarged transparent view of some of flow paths in the flow path member210formed by joining the first to third flow path members in the second embodiment, seen from a side of a surface on which the ejection module200of the first flow path member50is mounted. The individual flow paths213and214which are formed in the first flow path member50are formed obliquely to the conveying direction of the recording medium at a communication port51side, but are formed parallel to the conveying direction of the recording medium at a communication port61side. When the distance of the adjacent individual flow paths213and214is such that the distances of the communication ports61can be sufficiently ensured as compared with the communication port51side, the communication port61sides of the respective individual flow paths do not have to be formed obliquely to the conveying direction of the recording medium, but may be formed parallel as illustrated inFIG. 16. The structure of the first embodiment and the structure of the second embodiment can be favorably selected in accordance with the positions where the communication ports61are disposed.

In this way, in the present disclosure, the individual flow paths213and214run in the direction extending obliquely to the moving direction of the recording medium, at least in a range overlapping the recording element substrate10from the portion connected to the liquid supply path18or the liquid collection path19as seen from the ejection port array surface. However, the individual flow paths213and214may run parallel to the moving direction of the recording medium in a position that does not overlap the recording element substrate10, as seen from the ejection port array surface10a.

Third Embodiment

A third embodiment of the present disclosure will be described hereinafter.

FIGS. 17A to 17Fare views illustrating front surfaces and back surfaces of the first to third flow path members in the present embodiment.FIG. 17Aillustrates a front surface of the first flow path member, andFIG. 17Billustrates a back surface of the first flow path member.FIG. 17Cillustrates a front surface of the second flow path member, andFIG. 17Dillustrates a back surface of the second flow path member.FIG. 17Eillustrates a front surface of the third flow path member, andFIG. 17Fillustrates a back surface of the third flow path member. In the present embodiment, the flow paths provided in the second flow path member60are formed into a taper shape toward a front surface side illustrated inFIG. 17Cfrom a back surface side illustrated inFIG. 17D.FIG. 18which is a sectional view illustrates the flow paths in the taper shape of the second flow path member60. The flow paths of the second flow path member60are formed into the taper shape in this way, so that the pitch of the flow paths at the first flow path member50side can be formed to be narrow with respect to the pitch of the flow paths at the third flow path member70side, and the individual flow paths of the first flow path member can be shortened. The length of the individual flow channel52being short means that the possibility of a trouble such as mixing of liquids (color mixing) and a leakage can be reduced in the individual flow path. In other words, the seal region between the individual flow paths has a higher reliability in sealing and a probability of occurrence of poor sealing is reduced, as a dimension in the width direction of the flow path is larger and a dimension in the longitudinal direction of the flow path is smaller. In the present embodiment, the common flow channels62in the taper shape is provided in the second flow path member which is a single member, and the communication ports61are formed in the front surface. However, the second flow path member of a multilayer structure may be formed by joining a plate member in which only the common flow channels62are formed, and a member on which the shapes of the communication ports61are formed.

Fourth Embodiment

A fourth embodiment of the present disclosure will be described hereinafter with use ofFIGS. 19 and 20.

FIG. 19is an enlarged transparent view of part of flow paths in the flow path member210that is formed by joining the first to third flow path members in the present embodiment, as seen from a side of a surface on which an ejection module is mounted.FIG. 20is a view illustrating a positional relation of the liquid communication ports31of the support member30, and the liquid supply paths18and the liquid collection paths19of the recording element substrate10. Though not illustrated inFIG. 20, the communication ports51are provided in positions projected to overlap the openings21, and the openings21and the communication ports51communicate with each other. In the present embodiment, for a pair of the liquid supply path18and the liquid collection path19of the recording element substrate10, only one individual flow path (213or214) that communicates with the liquid supply path18and the liquid collection path19is formed. The number of individual supply flow paths213which are connected to a pair of the common supply flow path211and the common collection flow path212is preferably the number of individual collection flow paths214which are connected to the common supply flow path211and the common collection flow path212of the pair, or more.

When the length of the recording element substrate10in the longitudinal direction of the liquid ejection head is not so long, and the length of the liquid supply path18from the opening21is short, density unevenness in the connecting portion of the recording element substrates due to a temperature increase of the liquid does not matter so much. In such a case, to one of the liquid supply paths18and one of the liquid collection paths19of the recording element substrate10, only one individual flow path (213or214) communicating with the liquid supply path18and the liquid collection path19may be formed as described above. Note that in the present embodiment, sealing between the individual flow paths213and214can be reliably performed by forming the individual flow paths213and214to run in the direction extending obliquely to the conveying direction of the recording medium.

In the aforementioned embodiment, the liquid circulation path including the common supply flow path211, the individual supply flow path213, the liquid supply path18, the liquid collection path19, the individual collection flow path214and the common collection flow path212is formed. The individual flow paths213and214run in the direction extending obliquely to the moving direction of the recording medium from the portion connected to the liquid supply path18or the liquid collection path19, as seen from the ejection port array surface10a. The portions where the individual supply flow paths213and214run in the direction extending obliquely to the moving direction of the recording medium from the portion connected to the liquid supply path18or the liquid collection path19are parallel with each other. However, the present invention is not limited to this structure. When the liquid circulation path is not formed, a plurality of individual supply flow paths213run in the direction extending obliquely to the moving direction of the recording medium from the portion connected to the liquid supply path18. The portions running in the direction extending obliquely to the moving direction of the recording medium, of the plurality of individual supply flow paths213are parallel with one another.

The recording element substrate10may have an elongate plane shape extending in the direction (for example, the orthogonal direction) intersecting the moving direction of the recording medium. An angle at which the longitudinal direction of the recording element substrate10intersects the moving direction of the recording medium, and the angle at which the individual flow paths213and214run obliquely to the moving direction of the recording medium from the portion connected to the liquid supply path18or the liquid collection path19preferably correspond to each other.

According to the liquid ejection head of the present disclosure, even when the number of flow paths for supplying the liquid to the recording element substrates is large, reliability of sealing between the adjacent flow paths is high, and liquid ejection with high quality can be performed.

This application claims the benefit of Japanese Patent Application No. 2017-133996, filed Jul. 7, 2017, which is hereby incorporated by reference herein in its entirety.