JP2011161770A - Liquid ejection head and liquid ejector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid ejection head which can effectively suppress evaporation of a solvent. <P>SOLUTION: Nozzles 47 which eject a liquid are formed in a nozzle formation surface 43a of the liquid ejection head, and the liquid ejection head ejects the liquid from the nozzles while scan moving. A wall part 50 is provided which forms a regulation space 80 in a region opposed to the nozzle. The regulation space projects from the nozzle formation surface to regulate a flow of a gas generated through a forced convection T consequent to the scan movement. The regulation space is formed by a width and a height in a direction of the scan movement whereby the flow of the gas in a direction along the nozzle formation surface is non-formed with respect to the flow of the gas generated in the regulation space through the forced convection. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid ejecting head and a liquid ejecting apparatus.

  An ink jet printer (hereinafter referred to as a “printer”), which is a type of liquid ejecting apparatus, uses ink (liquid) from a nozzle formed on a nozzle forming surface of a recording head (liquid ejecting head) mounted on a carriage to a recording medium. Printing is carried out by jetting. Since the moisture (solvent) of the ink easily evaporates from the nozzle opening, the viscosity of the ink in the nozzle rises and the nozzle is likely to be clogged.

  The ink solvent evaporates easily when forced convection generated by the movement of the recording head directly hits the nozzle. For example, as shown in Patent Document 1 and Patent Document 2, a step is provided around the nozzle to force the nozzle to be forced. It may be possible to suppress direct convection.

Japanese Patent Laid-Open No. 4-176657 Japanese Patent Laid-Open No. 2004-322541

However, the following problems exist in the conventional technology as described above.
Since forced convection is affected by the airflow generated in the step, it is not a sufficient measure simply to provide a step.

  SUMMARY An advantage of some aspects of the invention is to provide a liquid ejecting head and a liquid ejecting apparatus that can effectively suppress evaporation of a solvent.

In order to achieve the above object, the present invention employs the following configuration.
The liquid ejecting head of the present invention is a liquid ejecting head in which a nozzle for ejecting liquid is formed on a nozzle forming surface, and scans and moves to eject the liquid from the nozzle. A wall for forming a restriction space for restricting a gas flow generated by forced convection associated with the nozzle in a region facing the nozzle, and the restriction space has a width and height in the scanning movement direction in the forced convection. The gas flow generated in the restriction space is formed in such a size that the gas flow in the direction along the nozzle forming surface is not formed.

  Therefore, in the liquid ejecting head of the present invention, forced convection associated with scanning movement occurs near the surface (upper surface) of the wall portion, so that it is possible to avoid forced convection directly hitting the nozzle. In addition, because of the size of the restriction space, the gas flow generated in the restriction space by forced convection is not in the direction along the nozzle formation surface, so that the gas contacts the liquid surface exposed from the nozzle substantially parallel to the nozzle formation surface. Time is shortened, and as a result, evaporation of the solvent contained in the liquid can be minimized.

  In the above liquid ejecting head, when the width in the scanning movement direction is B and the height is H, the restriction space satisfies the expression of B / H ≦ 1.0, and more preferably B A configuration that satisfies the equation /H≦0.5 can be suitably employed.

In the liquid ejecting head, a configuration in which the restriction space is formed across the plurality of nozzles arranged in a direction crossing the scanning movement direction can be suitably employed.
As a result, according to the present invention, it is possible to form a restriction space collectively as a concave line for the nozzles arranged in the direction intersecting the scanning movement direction, thereby improving the efficiency of the work required for head manufacture. it can.

In the liquid ejecting head, a configuration in which a plurality of the nozzles are formed and the restriction space is formed in each of the plurality of nozzles can be suitably employed.
As a result, in the present invention, it is possible to minimize evaporation of the solvent contained in the liquid from the nozzle by the gas flow from a direction different from the scanning movement direction.

And the liquid-jet apparatus of this invention is provided with the liquid-jet head described in 1. It is characterized by the above-mentioned.
Thereby, in this invention, it can suppress that a fluctuation | variation arises in a discharge characteristic by solvent evaporation, and can implement | achieve highly accurate liquid injection.

1 is a partially exploded view showing a schematic configuration of a printer 1 according to an embodiment of the present invention. 2 is a cross-sectional view illustrating the configuration of a recording head 3. FIG. 3 is a cross-sectional view of a main part of the recording head 3. 2 is a schematic diagram illustrating the configuration of a recording head 3 and an ink cartridge 6. FIG. It is a figure which shows a recording head and forced convection. It is a principal part detail drawing of the nozzle vicinity. It is a figure which shows the relationship between B / H and an evaporation rate. It is the figure visualized by varying B / H about the airflow which arises in the control space 80. FIG. It is a top view which shows other embodiment of a control space.

Hereinafter, embodiments of a liquid ejecting head and a liquid ejecting apparatus according to the invention will be described with reference to FIGS. 1 to 9.
The following embodiment shows one aspect of the present invention and does not limit the present invention, and can be arbitrarily changed within the scope of the technical idea of the present invention. Moreover, in the following drawings, in order to make each configuration easy to understand, the actual structure is different from the scale and number of each structure.

  In the present embodiment, an ink jet printer (hereinafter referred to as printer 1) is exemplified as the liquid ejecting apparatus according to the invention.

FIG. 1 is a partially exploded view showing a schematic configuration of a printer 1 according to an embodiment of the present invention.
The printer 1 includes a carriage 4 on which a sub tank (self-sealing valve) 2 and a recording head (liquid ejecting head) 3 are mounted, and a printer body 5.

The printer main body 5 includes a carriage moving mechanism (not shown) for reciprocating the carriage 4, a paper feeding mechanism (not shown) for conveying recording paper (liquid ejecting target), and nozzles of the recording head 3. A capping mechanism 14 used for a cleaning operation for sucking the sticky ink L, and an ink cartridge (cartridge body) 6 that stores the ink L supplied to the recording head 3 are provided.
In the following description, the reciprocating direction of the carriage is the X direction, the recording paper transport direction is the Y direction, and the substantially vertical direction perpendicular to the X direction and the Y direction is the Z direction.

The carriage moving mechanism includes a guide shaft 8 installed in the width direction of the printer main body 5, a pulse motor 9, a drive pulley 10 connected to a rotation shaft of the pulse motor 9 and driven to rotate by the pulse motor 9, and a drive The pulley 10 is an idle pulley 11 provided on the opposite side of the printer body 5 in the width direction, and a timing belt 12 that is stretched between the drive pulley 10 and the idle pulley 11 and connected to the carriage 4. It is composed of
The carriage 4 is configured to reciprocate in the main scanning direction along the guide shaft 8 by driving the pulse motor 9.

  The paper feed mechanism includes a paper feed motor M and a paper feed roller (not shown) that is rotationally driven by the paper feed motor M. The paper feed mechanism interlocks with the recording (printing / printing) operation of the recording paper. 13 are sequentially sent out.

As shown in FIG. 4, the capping mechanism 14 includes a cap member 15, a suction pump (pump device) 16, and the like.
The cap member 15 is a tray-like member having an open upper surface, and is made of an elastic member such as an elastomer. An ink absorber 77 is disposed inside the cap member 15. The ink absorber 77 has a high holding power of the ink L, and is made of a nonwoven fabric such as felt, for example.
The cap member 15 is disposed at the home position. This home position is set in an end area within the movement range of the carriage 4 and outside the recording area. When the power is turned off or when recording (liquid ejection processing) is not performed for a long time, the carriage is This is where 4 is located.

  When the carriage 4 is positioned at the home position, the cap member 15 contacts and seals the surface (that is, the nozzle opening surface 43a) of the nozzle substrate 43 (see FIG. 3) of the recording head 3. When the suction pump 16 is operated in this sealed state, the inside of the cap member 15 (sealed empty portion) is depressurized, and the ink L in the recording head 3 is forcibly discharged from the nozzle 47.

  Further, the cap member 15 receives the ink droplets D in a flushing process in which the ink droplets D are discharged to discharge the thickened ink L, bubbles, or the like before or during the recording operation by the recording head 3.

  FIG. 2 is a cross-sectional view illustrating the configuration of the recording head 3, and FIG. FIG. 4 is a schematic diagram illustrating the configuration of the recording head 3 and the ink cartridge 6.

The recording head 3 in this embodiment includes an introduction needle unit 17, a head case 18, a flow path unit 19, and an actuator unit 20 as main components.
Two ink introduction needles 22 are mounted side by side on the upper surface of the introduction needle unit 17 with the filter 21 interposed. The sub tanks 2 are respectively attached to these ink introduction needles 22. An ink introduction path 23 corresponding to each ink introduction needle 22 is formed inside the introduction needle unit 17.

The upper end of the ink introduction path 23 communicates with the ink introduction needle 22 via the filter 21, and the lower end communicates with the case flow path 25 formed inside the head case 18 via the packing 24.
Since this embodiment uses two types of ink, two subtanks 2 are provided. However, this embodiment is naturally applicable to a configuration using three or more types of ink. Is.

The sub tank 2 is molded from a resin material such as polypropylene. The sub-tank 2 is formed with a recess that becomes the ink chamber 27, and the ink chamber 27 is partitioned by attaching a transparent elastic sheet 26 to the opening surface of the recess.
In addition, a needle connection portion 28 into which the ink introduction needle 22 is inserted projects downward from the lower portion of the sub tank 2. The ink chamber 27 in the sub-tank 2 has a shallow mortar shape, and an opening on the upstream side of the connection channel 29 communicating with the needle connection portion 28 is located slightly below the vertical center on the side surface. The tank part filter 30 which filters the ink L is attached to this upstream side opening.
A seal member 31 into which the ink introduction needle 22 is liquid-tightly fitted is fitted in the internal space of the needle connection portion 28. As shown in FIG. 4, the sub-tank 2 is formed with an extending portion 32 having a communication groove portion 32 ′ communicating with the ink chamber 27, and an ink inlet 33 projects from the upper surface of the extending portion 32. It is installed.

An ink supply tube 34 that supplies ink L stored in the ink cartridge 6 is connected to the ink inlet 33. Accordingly, the ink L that has passed through the ink supply tube 34 flows into the ink chamber 27 from the ink inlet 33 through the communication groove 32 ′.
The elastic sheet 26 can be deformed in a direction in which the ink chamber 27 is contracted and a direction in which the ink chamber 27 is expanded. The pressure variation of the ink L is absorbed by the damper function due to the deformation of the elastic sheet 26. That is, the sub tank 2 functions as a pressure damper by the action of the elastic sheet 26. Therefore, the ink L is supplied to the recording head 3 side in a state where pressure fluctuation is absorbed in the sub tank 2.

The head case 18 is a hollow box-shaped member made of synthetic resin, the flow path unit 19 is joined to the lower end surface, and the actuator unit 20 is housed in the housing space 37 (see FIG. 3) formed inside. The introduction needle unit 17 is attached with the packing 24 interposed on the upper end surface opposite to the flow path unit 19 side.
A case channel 25 is provided inside the head case 18 so as to penetrate the height direction. The upper end of the case flow path 25 communicates with the ink introduction path 23 of the introduction needle unit 17 via the packing 24.
Further, the lower end of the case channel 25 communicates with the common ink chamber 44 in the channel unit 19. Therefore, the ink L introduced from the ink introduction needle 22 is supplied to the common ink chamber 44 side through the ink introduction path 23 and the case flow path 25.

The actuator unit 20 housed in the housing space 37 of the head case 18 includes a plurality of piezoelectric vibrators 38 arranged in a comb shape, a fixing plate 39 to which the piezoelectric vibrators 38 are joined, and a printer body. And a flexible cable 40 as a wiring member for supplying a drive signal from the side to the piezoelectric vibrator 38. Each piezoelectric vibrator 38 has a fixed end portion bonded to the fixed plate 39 and a free end portion protruding outward from the tip surface of the fixed plate 39. That is, each piezoelectric vibrator 38 is mounted on the fixed plate 39 in a so-called cantilever state.
The fixing plate 39 that supports each piezoelectric vibrator 38 is made of stainless steel having a thickness of about 1 mm, for example. The actuator unit 20 is housed and fixed in the housing space 37 by bonding the back surface of the fixed plate 39 to the inner wall surface of the case that defines the housing space 37.

The flow path unit 19 is manufactured by joining and integrating with a bonding agent in a state in which flow path unit constituting members including a vibration plate (sealing plate) 41, a flow path substrate 42, and a nozzle substrate 43 are laminated. A member that forms a series of ink flow paths (liquid flow paths) from the common ink chamber 44 to the nozzle 47 through the ink supply port 45 and the pressure chamber 46. The pressure chamber 46 is formed as an elongated chamber in a direction perpendicular to the direction in which the nozzles 47 are arranged (nozzle row direction).
The common ink chamber 44 communicates with the case flow path 25 and is a chamber into which ink L is introduced from the ink introduction needle 22 side.
The ink L introduced into the common ink chamber 44 is distributed and supplied to the pressure chambers 46 through the ink supply ports 45.

The nozzle substrate 43 disposed at the bottom of the flow path unit 19 is a thin metal plate material in which a plurality of nozzles 47 are opened in a row at a pitch (for example, 180 dpi) corresponding to the dot formation density. The nozzle substrate 43 of the present embodiment is made of a stainless steel plate material. In the present embodiment, a plurality of rows of nozzles 47 (that is, nozzle rows) are arranged in parallel corresponding to each sub tank 2. One nozzle row is composed of 180 nozzles 47, for example.
A wall 50 is discharged and provided on the nozzle forming surface 43 a of the nozzle substrate 43 so as to surround the periphery of the nozzle 47.

  More specifically, as shown in FIG. 5, a plurality of nozzles 47 (nozzle rows) are spaced on the nozzle substrate 43 along the X direction, which is the scanning movement direction (scanning movement direction) of the carriage 4 (see FIG. 5). 5 is 6 rows). As shown in FIGS. 5 and 6, a wall portion 50 is provided on the nozzle forming surface 43 a for each nozzle 47 so as to protrude toward the recording paper P toward the −Z side. The wall portion 50 is formed in a substantially cylindrical shape surrounding the periphery of the nozzle 47, and forms a regulation space 80 in a region facing the nozzle 47 on the recording paper P side.

The restriction space 80 is a space that restricts the flow of gas (hereinafter referred to as an airflow) that strikes the nozzle 47 by forced convection that occurs between the recording head 3 and mainly the recording paper P as the carriage 4 moves. , The width B and the height H in the X direction are set based on the evaporation rate of the ink solvent.
Specifically, in the present embodiment, with respect to the air flow generated in the restricted space 80 by forced convection, B / H ≦ 1.B is set to a size that prevents the air flow in the X direction along the nozzle forming surface 43a from being formed. The width B and the height H of the restriction space 80 are set so as to be 0, more preferably B / H ≦ 0.5.

  A flow path substrate 42 disposed between the nozzle substrate 43 and the vibration plate 41 is a flow path portion that becomes an ink flow path, specifically, a common ink chamber 44, an ink supply port 45, and an empty space that becomes a pressure chamber 46. It is a plate-like member in which a section is formed.

  In the present embodiment, the flow path substrate 42 is manufactured by subjecting a silicon wafer, which is a crystalline base material, to anisotropic etching. The vibration plate 41 is a double-structured composite plate material in which an elastic film is laminated on a metal support plate such as stainless steel. The part corresponding to the pressure chamber 46 of the vibration plate 41 is formed with an island portion 48 to which the tip surface of the piezoelectric vibrator 38 is joined by removing the support plate in an annular shape by etching or the like. Functions as a diaphragm. That is, the diaphragm 41 is configured such that the elastic film around the island portion 48 is elastically deformed in accordance with the operation of the piezoelectric vibrator 38. The vibration plate 41 also seals one opening surface of the flow path substrate 42 and functions as a compliance portion 49. As for the portion corresponding to the compliance portion 49, the support plate is removed by etching or the like in the same manner as the diaphragm portion to make only the elastic film.

  In the recording head 3, when a drive signal is supplied to the piezoelectric vibrator 38 through the flexible cable 40, the piezoelectric vibrator 38 expands and contracts in the longitudinal direction of the element, and accordingly, the island portion 48 enters the pressure chamber 46. Move in the direction of approaching or separating. As a result, the volume of the pressure chamber 46 changes, and the pressure fluctuation occurs in the ink L in the pressure chamber 46. The ink droplet D is ejected from the nozzle 47 by this pressure fluctuation.

As shown in FIG. 4, the ink cartridge 6 includes a case member 51 formed in a hollow box shape and an ink pack 52 formed of a plastic material. An ink pack is provided in a storage chamber in the case member 51. 52 is accommodated.
The ink cartridge 6 communicates with one end of the ink supply tube 34 and is configured to supply the ink L in the ink pack 52 to the recording head 3 side due to a water head difference from the nozzle opening surface 43a of the recording head 3. Has been. Specifically, the relative positional relationship in the weight direction between the ink cartridge 6 and the recording head 3 is set so that a slight negative pressure is applied to the meniscus of the nozzle 47.
Then, the ink L is supplied to the pressure chamber 46 and the ink L in the pressure chamber 46 is discharged by a pressure change caused by driving the piezoelectric vibrator 38.

  In the printer 1 configured as described above, when the recording head 3 moves in the X direction together with the carriage 4, forced convection T is generated as shown in FIG. 5, and the restriction space 80 corresponds to B / H described above. Thus, an air flow accompanying forced convection T is generated.

FIG. 7 is a diagram showing the relationship between B / H and the evaporation rate.
As shown in this figure, the evaporation rate shows a gradual increasing tendency after it rapidly increases as B / H increases.

FIG. 8 shows the air flow generated in the restricted space 80 visualized with different B / H. FIG. 8A shows B / H = 3.0, and FIG. 8B shows B / H = 2. 0.0, FIG. 8C shows the state when B / H = 1.0, and FIG. 8D shows the state when B / H = 0.5.
As shown in these figures, when B / H = 3.0, 2.0, an airflow is generated along the X direction in the vicinity of the nozzle forming surface 43a, but B / H = 1.0, At 0.5, no airflow along the X direction is seen in the vicinity of the nozzle forming surface 43a.

  When the airflow does not flow in the X direction as in the case of B / H = 3.0 and 2.0, the airflow contacts the ink surface exposed from the nozzle 47 substantially parallel to the nozzle formation surface 43a. As a result, the evaporation of the solvent (such as water) contained in the ink is minimized.

Thus, in the present embodiment, the width B and the height H in the X direction of the restriction space 80 are formed with a size that does not form the airflow in the direction along the nozzle forming surface 43a with respect to the airflow generated in the restriction space 80. Therefore, it is possible to effectively suppress the evaporation of the solvent.
For this reason, in the printer 1 of the present embodiment, it is possible to suppress fluctuations in the ink ejection characteristics due to the evaporation of the ink solvent, and it is possible to realize highly accurate liquid ejection.

  Further, in the present embodiment, since the restriction space 80 is formed by each of the plurality of nozzles 47, evaporation of the solvent contained in the ink from the nozzle 47 is minimized by the flow of gas from the direction different from the scanning movement direction. It becomes possible to suppress to the limit.

  As described above, the preferred embodiments according to the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

For example, in the above embodiment, the restriction space 80 is formed for each of the plurality of nozzles 47. However, the present invention is not limited to this, and for example, as shown in FIG. 9, a direction substantially orthogonal to the scanning movement direction. For the nozzle row in which the nozzles 47 are arranged, a concave restriction space 80 </ b> A straddling the plurality of nozzles 47 may be formed.
In this case, the restriction space 80A can be collectively formed for the nozzles arranged in the direction intersecting the scanning movement direction, and the work required for head manufacture can be made efficient. In this configuration as well, it is preferable to shield the end of the restriction space 80A in the Y direction with the wall 50 in order to minimize the influence of forced convection on the nozzle 47 located at the end.

In the above-described embodiment, the case where the liquid ejecting apparatus is an ink jet printer has been described as an example. However, the liquid ejecting apparatus is not limited to the ink jet printer, and may be an apparatus such as a copying machine or a facsimile.
Further, in the above-described embodiment, the case where the liquid ejecting apparatus is a fluid ejecting apparatus that ejects a liquid such as ink as a fluid has been described as an example. However, the liquid ejecting apparatus of the present invention is not limited to ink. The present invention can be applied to a liquid ejecting apparatus that ejects or discharges liquid. Examples of the liquid that can be ejected by the liquid ejecting apparatus include a liquid material in which particles of a functional material are dispersed or dissolved, and a gel-like fluid.

  In the above-described embodiment, as the liquid ejected from the liquid ejecting apparatus, not only ink but also a liquid corresponding to a specific application can be applied. By providing the liquid ejecting apparatus with an ejecting head capable of ejecting a liquid corresponding to the specific application, ejecting the liquid corresponding to the specific application from the ejecting head, and attaching the liquid to a predetermined object, A given device can be manufactured. For example, the liquid ejecting apparatus of the present invention uses, as a predetermined dispersion medium (solvent), materials such as electrode materials and color materials used for manufacturing liquid crystal displays, EL (electroluminescence) displays, and surface-emitting displays (FEDs). The present invention can be applied to a liquid ejecting apparatus that ejects a dispersed (dissolved) liquid (liquid material).

In addition, the liquid ejecting apparatus may be a liquid ejecting apparatus that ejects a biological organic material used for biochip manufacturing, or a liquid ejecting apparatus that ejects a liquid that is used as a precision pipette and serves as a sample.
In addition, transparent resin liquids such as UV curable resin to form liquid injection devices that pinpoint lubricant oil onto precision machines such as watches and cameras, and micro hemispherical lenses (optical lenses) used in optical communication elements. May be a liquid ejecting apparatus that ejects a liquid onto the substrate, a liquid ejecting apparatus that ejects an etching solution such as acid or alkali to etch the substrate, and a liquid ejecting apparatus that ejects a gel. The present invention can be applied to any one of these liquid ejecting apparatuses.

  DESCRIPTION OF SYMBOLS 1 ... Inkjet printer (liquid ejecting apparatus), 3 ... Recording head (liquid ejecting head), 43a ... Nozzle formation surface, 47 ... Nozzle, 80 ... Restricted space, 80A ... Restricted space, T ... Forced convection

Claims (6)

A liquid ejecting head in which a nozzle for ejecting liquid is formed on a nozzle forming surface, scans and ejects the liquid from the nozzle,
Providing a wall that protrudes from the nozzle forming surface and forms a restriction space that restricts the flow of gas generated by forced convection accompanying the scanning movement in a region facing the nozzle,
The restriction space is formed in such a size that the width and height in the scanning movement direction is such that the gas flow in the direction along the nozzle forming surface is not formed with respect to the gas flow generated in the restriction space by the forced convection. A liquid ejecting head. The liquid ejecting head according to claim 1,
The restriction space has a width B in the scanning movement direction and a height H,
B / H ≦ 1.0
A liquid jet head satisfying the following formula: The liquid ejecting head according to claim 2.
The regulatory space is
B / H ≦ 0.5
A liquid jet head satisfying the following formula: In the liquid jet head according to any one of claims 1 to 3,
The liquid ejecting head according to claim 1, wherein the restriction space is formed across a plurality of the nozzles arranged in a direction intersecting the scanning movement direction. In the liquid jet head according to any one of claims 1 to 3,
A plurality of the nozzles are formed,
The liquid ejection head, wherein the restriction space is formed in each of the plurality of nozzles.   A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1.

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