JP2013176894A - Liquid ejecting head, and liquid ejecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid ejecting head capable of preventing crosstalk in ejecting liquid, and a liquid ejecting apparatus.SOLUTION: In a recording head including: a pressure chamber board 15 for zoning a plurality of pressure chambers 20 communicating with nozzles 23 by barrier ribs; a piezoelectric element 18 for generating a pressure variation in ink in the pressure chambers; a nozzle forming board 15 jointed to the pressure chamber board by an adhesive to partition bottoms of the pressure chambers in which organic solvent-based ink having a compression rate larger than a compression rate of water is ejected from the nozzles by generating the pressure variation in the pressure chambers, when it is assumed that, in a pressure chamber parallel arrangement direction, the width of the pressure chamber is W, the width of the barrier rib is D, the width in the pressure chamber parallel arrangement direction of the adhesive having leaked to the pressure chamber side from a part between the lower end of the barrier rib and a bottom member, and coming into a solidified state at a corner partitioned by the barrier rib and the bottom member is L, and the height of the pressure chamber in a lamination direction of the pressure chamber board and the bottom member is H, 0.05≤L/W≤0.3 and 3.8<H/D≤9.0 are satisfied.

Description

  The present invention relates to a liquid ejecting head mounted on a liquid ejecting apparatus such as an ink jet recording apparatus, and a liquid ejecting apparatus including the liquid ejecting head, and in particular, a working surface constituting a part of a pressure chamber communicating with a nozzle is deformed. The present invention relates to a liquid ejecting head that ejects liquid from a nozzle by causing a pressure fluctuation in the liquid in the pressure chamber, and a liquid ejecting apparatus.

  The liquid ejecting apparatus is an apparatus that includes a liquid ejecting head capable of ejecting liquid as droplets from a nozzle and ejects various liquids from the liquid ejecting head. A typical example of the liquid ejecting apparatus is an ink jet recording that includes an ink jet recording head (hereinafter referred to as a recording head) and performs recording by ejecting liquid ink as ink droplets from the nozzle of the recording head. An image recording apparatus such as an apparatus (printer) can be given. In addition, liquid ejecting apparatuses for ejecting various types of liquids such as color materials used for color filters such as liquid crystal displays, organic materials used for organic EL (Electro Luminescence) displays, electrode materials used for electrode formation, etc. Is used. The recording head for the image recording apparatus ejects liquid ink, and the color material ejecting head for the display manufacturing apparatus ejects solutions of R (Red), G (Green), and B (Blue) color materials. The electrode material ejecting head for the electrode forming apparatus ejects a liquid electrode material, and the bioorganic matter ejecting head for the chip manufacturing apparatus ejects a bioorganic solution.

  The recording head mounted on the printer introduces ink from an ink supply source such as an ink cartridge into a pressure chamber (pressure generation chamber), and operates pressure generation means such as a piezoelectric element and a heating element to operate the pressure chamber. There is a configuration in which a pressure fluctuation is generated in the ink, and the ink in the pressure chamber is ejected as an ink droplet from a nozzle using the pressure fluctuation (see, for example, Patent Document 1). In such a recording head, a plurality of nozzles are arranged at a high density (for example, a pitch corresponding to 360 dpi) in order to cope with an improvement in image quality of a recorded image. As a result, the pressure chambers communicating with the nozzles are also formed with high density, and as a result, the partition walls that partition adjacent pressure chambers and other flow paths tend to be very thin.

JP 2011-194783 A

  Here, for example, when ink is ejected from a certain nozzle, there is a possibility that the partition wall is displaced to the adjacent pressure chamber side in accordance with the pressure fluctuation of the ink in the pressure chamber due to the driving of the pressure generating means. In this regard, in a configuration in which a substrate that forms a pressure chamber and a member that is stacked on the substrate and defines a bottom portion of the pressure chamber, such as a nozzle plate, are bonded with an adhesive, the adhesive swells depending on the ink. As a result, the bonding force may decrease. In this case, the fixing force at the lower end of the partition wall of the pressure chamber is reduced. Then, when pressure fluctuations occur in the pressure chamber when ink is ejected from the nozzles, the partition is more easily displaced by the pressure, resulting in a pressure loss, and a drop in ink droplet flying speed or ink. There is a risk of crosstalk in which the ejection characteristics of ink droplets change, such as a drop in droplet volume. That is, when ink is ejected simultaneously from a plurality of adjacent nozzles (when all are ON) and when ink is ejected independently from one nozzle (when ink is not ejected simultaneously from adjacent nozzles) (when 1 ON) As a result, the ejection characteristics such as the amount of ink and the flying speed fluctuate.

  In recent years, a liquid ejecting head may be used for a purpose of ejecting an organic solvent-based (ecosolvent-based) ink having higher weather resistance than a conventional water-based ink. This organic solvent-based ink tends to cause swelling of the adhesive as compared with the water-based ink. In addition, the compressibility of this organic solvent-based ink (an amount indicating how much the original volume changes when a pressure of 1 [Pa] is applied at a constant temperature) is the same under the same environmental conditions. It is larger than the compressibility of water or water-based ink at (temperature and pressure). There is a problem that the deterioration of the above-mentioned crosstalk becomes more remarkable in such applications in which ink having a higher compression ratio than water is ejected. That is, when the pressure acts on the partition due to an increase in pressure in the pressure chamber as described above, when the ink filled in the adjacent pressure chamber is an organic solvent, the organic solvent-based ink with respect to the partition The reaction force is smaller than that of water-based ink. For this reason, the partition wall is easily displaced (deformed) by the adjacent pressure chamber side, and as a result, the crosstalk is deteriorated.

  Note that such a problem is not only caused by an ink jet recording apparatus equipped with a recording head for ejecting ink, but also by causing liquid to be ejected from nozzles by causing pressure fluctuations in the liquid in the pressure chamber by driving the pressure generating means. This also exists in the liquid ejecting head and the liquid ejecting apparatus.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a liquid ejecting head and a liquid ejecting apparatus capable of suppressing crosstalk during liquid ejecting.

The liquid jet head of the present invention has been proposed in order to achieve the above object, and includes a pressure chamber substrate in which a plurality of pressure chambers communicating with nozzles are partitioned by partition walls,
Pressure generating means for causing a pressure fluctuation in the liquid in the pressure chamber;
A bottom member that is bonded to the pressure chamber substrate by an adhesive and defines a bottom portion of the pressure chamber;
A liquid ejecting head that ejects a liquid having a compressibility higher than the compressibility of water from the nozzle by causing the pressure generating unit to drive and generate a pressure fluctuation in the pressure chamber,
In the pressure chamber juxtaposing direction, the width of the pressure chamber is W, the width of the partition wall is D, and the partition wall and the bottom member are leaked to the pressure chamber side from between the lower end portion of the partition wall and the bottom member. The width in the pressure chamber juxtaposition direction of the adhesive in a solidified state at the corners to be partitioned is L,
In the stacking direction of the pressure chamber substrate and the bottom member, when the height of the pressure chamber is H,
0.05 ≦ L / W ≦ 0.3
And 3.8 <H / D ≦ 9.0
It is characterized by satisfying.

  According to the present invention, the adhesive leaks from the space between the lower end portion of the partition wall and the bottom member to the pressure chamber side and is solidified at the corner portion defined by the partition wall and the bottom member. When the width is L, by satisfying 0.05 ≦ L / W ≦ 0.3, it is possible to prevent the trouble caused by the flow of the adhesive, that is, the trouble that the adhesive regulates the operation of the pressure generating means. The bonding strength between the lower end portion of the partition and the bottom member is increased. For this reason, when the pressure generating means is driven to eject the liquid from the nozzle and the pressure fluctuation occurs in the pressure chamber, the partition is suppressed from being displaced. Thereby, the pressure loss at the time of liquid injection is reduced, and crosstalk between adjacent nozzles is suppressed. That is, fluctuations in ejection characteristics (the amount of liquid ejected from the nozzle and the flying speed) are suppressed. Further, assuming that the height of the pressure chamber is H and the thickness of the partition wall is D, by satisfying 3.8 <H / D ≦ 9.0, the liquid injection amount can be sufficiently secured and the partition wall itself Strength is increased. Thereby, crosstalk is more reliably suppressed.

In the above configuration,
0.7 <H / W ≦ 1.6
It is desirable to satisfy.

  Furthermore, in each of the above-described configurations, the liquid uses an organic solvent as a solvent, and the swelling rate of the adhesive in a state immersed in the liquid for 100 hours in an environment of 40 ° C. is 10% or less. It is desirable to adopt.

  According to this configuration, since the swelling rate of the adhesive in the state immersed in the liquid is 10% or less, the swelling of the adhesive is suppressed, and the bonding strength between the lower end of the partition wall and the bottom member is reduced. The decrease is further suppressed. This contributes to the suppression of the crosstalk.

  Moreover, in the said structure, it is desirable to employ | adopt the structure which mix | blends the silica with 5 weight% or more and 10 weight% or less of the epoxy adhesive for the said adhesive agent.

  According to this configuration, in the case of an adhesive containing silica, the viscosity is increased as compared to the case where the adhesive is not added, so that it is possible to more reliably suppress problems caused by the flow of the adhesive.

  The liquid ejecting apparatus according to the aspect of the invention includes the liquid ejecting head having any one of the above-described configurations.

FIG. 3 is a perspective view illustrating a configuration of a printer. FIG. 3 is a diagram illustrating a configuration of a recording head. FIG. 3 is an enlarged cross-sectional view of a main part of the recording head. It is a table | surface which shows about the crosstalk rate when the ratio of the protrusion width | variety of the adhesive agent with respect to the width | variety of a pressure chamber is changed, and the outflow change of an adhesive agent. It is a graph which shows about the crosstalk rate change when changing the ratio of the height of a pressure chamber to the thickness of a partition. It is a graph which shows about the crosstalk rate change when changing the ratio of the height of a pressure chamber to the width of a pressure chamber.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. In the embodiments described below, various limitations are made as preferred specific examples of the present invention. However, the scope of the present invention is not limited to the following description unless otherwise specified. However, the present invention is not limited to these embodiments. In the following description, an ink jet recording apparatus (hereinafter referred to as a printer 1) equipped with a recording head 2 which is a kind of liquid ejecting head will be described as an example of the liquid ejecting apparatus of the present invention.

  FIG. 1 is a perspective view showing the configuration of the printer 1. The printer 1 includes a carriage 4 to which a recording head 2 is attached and an ink cartridge 3 which is a kind of liquid supply source is detachably attached, and a platen 5 disposed below the recording head 2 during a recording operation. The carriage 4 moves in the sub-scanning direction orthogonal to the main scanning direction, and the carriage moving mechanism 7 for reciprocating the carriage 4 in the paper width direction of the recording paper 6 (a kind of the recording medium and the landing target), that is, the main scanning direction. And a paper feed mechanism 8 that performs the operation.

  The carriage 4 is attached while being supported by a guide rod 9 installed in the main scanning direction, and is configured to move in the main scanning direction along the guide rod 9 by the operation of the carriage moving mechanism 7. ing. The position of the carriage 4 in the main scanning direction is detected by the linear encoder 10, and the detection signal, that is, the encoder pulse is transmitted to a printer controller (not shown). The linear encoder 10 is a kind of position information output means, and outputs an encoder pulse corresponding to the scanning position of the recording head 2 as position information in the main scanning direction.

  A home position serving as a base point for scanning of the carriage is set in an end area outside the recording area within the movement range of the carriage 4. In the home position in the present embodiment, a capping member 11 for sealing the nozzle formation surface (nozzle formation substrate 15: see FIG. 2) of the recording head 2 and a wiper member 12 for wiping the nozzle formation surface are disposed. ing. The printer 1 is bi-directional between when the carriage 4 moves from the home position toward the opposite end and when the carriage 4 returns from the opposite end to the home position. So-called bidirectional recording in which characters, images, etc. are recorded on the recording paper 6 is possible.

  2A and 2B are diagrams illustrating a configuration of the recording head 2 according to the present embodiment, in which FIG. 2A is a plan view of the recording head 2, FIG. 2B is a cross-sectional view taken along the line AA ′ in FIG. It is BB 'sectional view taken on the line in (a). In addition, illustration of the protective substrate 19 is abbreviate | omitted in FIG.2 (c). Moreover, although the structure for four nozzles is illustrated in FIG. 2, the structure corresponding to the remaining other nozzles is also the same. The recording head 2 in this embodiment is configured by laminating a pressure chamber substrate 14, a nozzle forming substrate 15, an elastic film 16, an insulator film 17, a piezoelectric element 18, a protective substrate 19, and the like.

  The pressure chamber substrate 14 is a plate material made of, for example, a silicon single crystal substrate. On the pressure chamber substrate 14, a plurality of pressure chambers 20 are arranged in parallel in the width direction (nozzle row direction (first direction)) with the partition wall 37 interposed therebetween. In the present embodiment, 360 pressure chambers 20 are formed per inch. The height H of the pressure chamber 20 (height of the partition wall 37) H and the thickness D of the partition wall 37 are within a range in which the ink ejection efficiency (ink ejection amount per unit time) does not deteriorate. / D is set to be 9.0 or less. The width W of the pressure chamber 20 (inner dimension in the direction in which the pressure chambers are arranged) W is 1.6 or less in the ratio H / W to the height H of the pressure chamber 20 within a range where the ink ejection efficiency does not deteriorate. Is set to These relationships will be described later. In addition, the range in which the ink ejection efficiency does not deteriorate refers to the amount of ink ejected from the nozzles 23 per unit time when the piezoelectric element 18 is driven by applying a predetermined voltage according to the specifications of the printer 1. Means within expected tolerances.

  A communication portion 21 is formed in a region outside the side opposite to the side communicating with the nozzle 23 in the longitudinal direction of the pressure chamber substrate 14 in the longitudinal direction of the pressure chamber 20 (direction perpendicular to the nozzle row direction). Each pressure chamber 20 communicates with each other via an ink supply path 22 provided for each pressure chamber 20. The communication portion 21 constitutes a part of a reservoir 30 that communicates with a reservoir portion 29 of the protective substrate 19 described later and serves as a common ink chamber for the pressure chambers 20. The ink supply path 22 is formed with a width narrower than that of the pressure chamber 20, and imparts flow path resistance to the ink flowing into the pressure chamber 20 from the communication portion 21. Channels such as the pressure chamber 20 and the ink supply channel 22 in the pressure chamber substrate 14 are formed by anisotropic etching.

On the lower surface of the pressure chamber substrate 14, a nozzle forming substrate 15 in which a plurality of nozzles 23 are opened in a row corresponding to each pressure chamber 20 is bonded by an adhesive 40. As a result, the opening on the lower surface side of the pressure chamber 20 is sealed by the nozzle forming substrate 15 and the bottom of the pressure chamber 20 is defined. That is, the nozzle forming substrate 15 in the present embodiment functions as a bottom member in the present invention. The joining of the pressure chamber substrate 14 and the nozzle forming substrate 15 will be described later. An elastic film 16 made of, for example, silicon dioxide (SiO ₂ ) is formed on the upper surface of the pressure chamber substrate 14. The portion of the elastic film 16 that seals the opening of the pressure chamber 20 functions as an operating surface. An insulating film 17 made of zirconium oxide (ZrO ₂ ) is formed on the elastic film 16, and a lower electrode 24, a piezoelectric body 25, and an upper electrode 26 are further formed on the insulating film 17. These are formed, and these constitute a piezoelectric element 18 (a kind of pressure generating means) in a laminated state.

  In general, one electrode of the piezoelectric element 18 is used as a common electrode, and the other electrode (positive electrode or individual electrode) and the piezoelectric body 25 are patterned for each pressure chamber 20. A portion that is constituted by any one of the patterned electrodes and the piezoelectric body 25 and in which piezoelectric distortion is generated by applying a voltage to both electrodes is referred to as a piezoelectric active portion. In this embodiment, the lower electrode 24 is a common electrode for the piezoelectric element 18 and the upper electrode 26 is an individual electrode for the piezoelectric element 18. Therefore, it is possible to adopt a configuration in which these are entirely reversed. In any case, a piezoelectric active part is formed for each pressure chamber 20. Further, a lead electrode 27 made of, for example, gold (Au) or the like is connected to the upper electrode 26 of each piezoelectric element 18.

  On the surface of the pressure chamber substrate 14 on the piezoelectric element 18 side, a protective substrate 19 having a piezoelectric element holding portion 28 that is a space having a size that does not hinder the displacement is bonded to a region facing the piezoelectric element 18. Yes. Further, the protective substrate 19 is provided with a reservoir portion 29 in a region corresponding to the communication portion 21 of the pressure chamber substrate 14. The reservoir portion 29 is formed in the protective substrate 19 as a through hole having a rectangular opening shape elongated along the direction in which the pressure chambers 20 are juxtaposed. As described above, the reservoir portion 29 is connected to the communication portion 21 of the pressure chamber substrate 14. The reservoir 30 is defined in communication. The reservoir 30 is provided for each type of ink (for each color), and common ink is stored in the plurality of pressure chambers 20.

  A through hole 31 that penetrates the protective substrate 19 in the thickness direction is provided in a region between the piezoelectric element holding portion 28 and the reservoir portion 29 of the protective substrate 19. A part and the tip of the lead electrode 27 are exposed. A compliance substrate 34 including a sealing film 32 and a fixing plate 33 is bonded onto the protective substrate 19. The sealing film 32 is made of a flexible material (for example, polyphenylene sulfide film), and one surface of the reservoir portion 29 is sealed by the sealing film 32. The fixing plate 33 is made of a hard material such as metal (for example, stainless steel). A region of the fixing plate 33 facing the reservoir 30 is an opening 35 that penetrates the thickness direction. For this reason, one surface of the reservoir 30 is sealed only by the flexible sealing film 32.

  In the recording head 2 configured as described above, ink is taken in from an ink supply means such as an ink cartridge and is filled with ink from the reservoir 30 to the nozzle 23. Then, by supplying a drive signal from the printer main body side, an electric field corresponding to the potential difference between the two electrodes is applied between the lower electrode 24 and the upper electrode 26 corresponding to the pressure chamber 20, and the piezoelectric element 18 and the operation surface. When the (elastic film 16) is bent and deformed, a pressure fluctuation occurs in the pressure chamber 20. By controlling the pressure fluctuation, ink is ejected from the nozzle 23, or the meniscus in the nozzle 23 is vibrated slightly to the extent that ink is not ejected.

Here, in the recording head 2, on the premise that the organic solvent-based ink is ejected, measures are taken to suppress crosstalk caused by the organic solvent-based ink. Specifically, the adhesive 40 for joining the pressure chamber substrate 14 and the nozzle forming substrate 15 was actively leaked to the pressure chamber 20 side from between the lower end portion of the partition wall 37 and the nozzle forming substrate 15 (extruding). In this state, the bonding strength between the lower end portion of the partition wall 37 and the nozzle forming substrate 15 is increased. Specifically, as shown in FIG. 3, the inner method of the pressure chambers 20 in the pressure chamber side-by-side direction (nozzle row direction) is set to W, and between the lower end portion of the partition wall 37 and the nozzle forming substrate 15 to the pressure chamber 20 side. When the width in the pressure chamber juxtaposition direction of the adhesive 40 in a state of flowing out and solidifying at the corners defined by the partition walls 37 and the nozzle forming substrate 15 (hereinafter referred to as a protruding width as appropriate) is L, The application amount of the adhesive 40 is adjusted so that the ratio of the protrusion width L to the width W of the chamber 20 satisfies the following expression (1).
0.05 ≦ L / W ≦ 0.3 (1)
The protruding width L of the adhesive 40 indicates the width of one side of the protruding adhesive 40 generated on both sides of the pressure chamber 20 in the width direction. The present invention pays attention to the protruding width of the adhesive 40 on both sides of the pressure chamber 20 in the width direction, but the protruding of the adhesive 40 occurs similarly on both sides of the pressure chamber 20 in the longitudinal direction.

With respect to the above-described adhesive 40, a compound in which silica (SiO ₂ ) is blended at 5 wt% or more and 10 wt% or less with respect to the epoxy adhesive as the main component is used. By using the adhesive 40 for joining the pressure chamber substrate 14 and the nozzle forming substrate 15, resistance to the organic solvent ink can be increased. Specifically, the swelling rate when the adhesive 40 is immersed in an organic solvent-based ink for 100 hours at a constant temperature, for example, 40 ° C., can be 10% or less. Here, the swelling rate is expressed by the following formula (2), where Wt is the initial weight of the adhesive 40 in the above state, and Wt ′ is the weight after the elapse of a fixed time.
{(Wt′−Wt) / Wt} × 100 [%] (2)
If the swelling rate exceeds 10%, the bonding force between the lower end portion of the partition wall 37 and the nozzle forming substrate 15 is reduced, and the partition wall 37 is easily displaced when subjected to pressure. Deterioration becomes remarkable.

  In the present embodiment, the elastic film 16, the insulator film 17, and the piezoelectric element 18 are formed on the upper surface of the pressure chamber substrate 14 (the surface opposite to the bonding surface with the nozzle forming substrate 15). After the flow paths such as the pressure chamber 20 and the communication portion 21 are formed in the etching process 14, the adhesive 40 is applied to the lower surface of the pressure chamber substrate 14 by film transfer. Here, regarding the adhesive 40, when silica is not added, while exhibiting ink resistance, the fluidity is higher than that of the conventional adhesive, so that it flows out to a region other than the part that requires the adhesive. There was a fault that it was easy to occur. On the other hand, in the case of the adhesive 40 in which silica is blended, the viscosity is increased as compared with the case in which the silica is not blended, and the above-described flow-out can be suppressed. Then, the nozzle forming substrate 15 is positioned on the lower surface of the pressure chamber substrate 14 and bonded by the adhesive 40. The amount of the adhesive 40 protruding to the pressure chamber 20 side is between the amount of the adhesive 40 transferred to the pressure chamber substrate 14 and the pressure chamber substrate 14 and the nozzle forming substrate 15 when the adhesive 40 is dried. It can be controlled by the magnitude of the load when the load is applied by a jig or the like.

  Thus, when the pressure chamber substrate 14 and the nozzle forming substrate 15 are joined by the adhesive 40, the adhesive 40 is positively applied to the pressure chamber 20 side from between the lower end portion of the partition wall 37 and the nozzle forming substrate 15. By solidifying in a leaked state, the bonding strength between the lower end portion of the partition wall 37 and the nozzle forming substrate 15 is increased. For this reason, even if the piezoelectric element 18 is driven to eject ink from the nozzle 23 and the pressure in the pressure chamber 20 increases, deformation and displacement of the partition wall 37 are suppressed. As a result, pressure loss during ink ejection is reduced, and crosstalk between adjacent nozzles is suppressed. That is, fluctuations in ink ejection characteristics (the amount of ink ejected from the nozzles 23 and the flying speed) can be suppressed.

FIG. 4 is a table showing changes in the crosstalk ratio and the flow of the adhesive 40 when the ratio of the protrusion width L to the width W of the pressure chamber 20 is changed. The figure also shows the experimental results at the temperature in the apparatus (for example, 40 ° C.) assumed for use of the printer 1. Here, the crosstalk (CT) rate means the ink flying speed Vm1 when ink is ejected simultaneously from a plurality of adjacent nozzles 23 (when all the nozzles are ON) and the ink is ejected independently from one nozzle 23. The degree of change in ejection characteristics represented by the ratio to the ink flying speed Vm2 in the case of 1 ON (when ON) is represented by the following equation (3).
CT rate = (1−Vm2 / Vm1) × 100 [%] (3)
For example, when Vm1 = 10 [m / s] and Vm2 = 8 [m / s], the crosstalk rate is 20%. When the printer 1 records an image or the like on a recording medium, the crosstalk rate is required to be at least 40% or less, desirably 30% or less. When the crosstalk ratio exceeds 40%, the landing position deviation of the ink ejected from the nozzle 23 on the recording medium (deviation from the target landing position) becomes remarkable, and so-called graininess or the like in the recorded image or the like. This is because the visual roughness becomes conspicuous. In general, the bonding strength due to the adhesive is likely to vary, so a margin is provided for the crosstalk rate of 40%. That is, the lower limit value of L / W is calculated based on a crosstalk rate of 30%. The crosstalk rate can also be expressed as a ratio of the ink weight Iw at all ON and 1 ON.

  Further, “flowing out” of the adhesive 40 means that when the adhesive 40 protrudes more than necessary to the pressure chamber 20 side, the protruding adhesive 40 flows out to a part other than necessary, particularly by surface tension. It means a phenomenon of moving along the partition wall 37 toward the elastic film 16 side. In particular, the adhesive 40 is likely to flow out by capillary force at the portion where the partition walls 37 of the pressure chamber 20 intersect. When the adhesive 40 reaches the elastic film 16 and is cured, the adhesive 40 restricts the displacement of the piezoelectric element 18 (and the elastic film 16), which may cause a problem in ink ejection. In FIG. 4, the state where the above-mentioned outflow did not occur is indicated by “◎”, the state where the outflow occurred but did not reach the elastic film 16, and the state where the outflow occurred and the adhesive 40 reached the elastic film 16 and the ink was ejected. A state where the problem is slight (a change in the amount of ink ejected or a deviation in landing position is within an allowable range), and the adhesive 40 reaches the elastic film 16 to cause a remarkable problem in ink ejection (the ink is discharged from the nozzle 23). A case where a failure such as a change in the ink amount or a deviation in the landing position exceeding the allowable range occurs even if the ejection is not performed is indicated by x.

  As shown in FIG. 4, when the ratio of the protrusion width L to the width W of the pressure chamber 20 satisfies the above formula (1), the crosstalk rate is suppressed to 20% or more and 30% or less, and the adhesive 40 flows out. Becomes “◎” or “○”, and it is possible to achieve both suppression of crosstalk and suppression of the flow of adhesive. On the other hand, when L / W is less than 0.05, the flow of the adhesive 40 is suppressed, but the crosstalk rate exceeds 30%, which is not suitable when considering the margin. Further, it was found that when L / W exceeds 0.3, the crosstalk rate can be suppressed to 20%, but the adhesive 40 flows out and becomes incompatible.

Next, the relationship among the height H of the pressure chamber 20, the width W of the pressure chamber 20, and the thickness D of the partition wall 37 will be described.
First, the relationship between the height H of the pressure chamber 20 and the thickness D of the partition wall 37 will be described. The ratio of the height H of the pressure chamber 20 to the thickness D of the partition wall 37 is set so as to satisfy the following formula (4).
3.8 <H / D ≦ 9.0 (4)

  FIG. 5 is a graph showing a change in the crosstalk ratio when the ratio of the height H of the pressure chamber 20 to the thickness D of the partition wall 37 is changed. The horizontal axis of the graph shown in FIG. 5 indicates H / D, and the vertical axis indicates the CT rate (see Equation (3)). In addition, square points in the graph shown in FIG. 5 indicate experimental values, and broken lines indicate approximate curves calculated from the experimental values. In the experiment, the ratio L / W of the protrusion width L to the width W of the pressure chamber 20 was set to 0.05.

  As shown in FIG. 5, it can be seen that the crosstalk rate exceeds 40% when H / D is greater than 9.0. As described above, when the crosstalk rate exceeds 40%, the landing position deviation of the ink ejected from the nozzle 23 on the recording medium becomes significant, and the visual roughness such as so-called graininess is recorded in the recorded image or the like. It will stand out. For this reason, it is desirable to suppress the crosstalk rate to 40% or less. Here, since the pressure chamber 20 and the partition wall 37 are formed by anisotropic etching, the height H of the pressure chamber 20 and the thickness D of the partition wall 37 are small, and the strength of the partition wall 37 itself is small. For this reason, it is not necessary to provide a margin for the crosstalk rate unlike the lower limit value of L / W described above, and the upper limit value of H / D is calculated based on the crosstalk rate of 40%.

  Further, as shown in FIG. 5, it can be seen that as the H / D becomes smaller, the crosstalk rate tends to be improved. However, experiments have shown that when H / D is 3.8 or less, the volume of the pressure chamber 20 decreases and the amount of ink ejected from the nozzles 23 per unit time, that is, the ink ejection efficiency deteriorates. It was. For this reason, it is not desirable to set H / D to 3.8 or less.

  That is, in addition to the above equation (1), the ratio of the height H of the pressure chamber 20 to the thickness D of the partition wall 37 is set so as to satisfy the equation (4), thereby ensuring a sufficient amount of ink ejection. The strength of the partition wall 37 itself can be increased. As a result, crosstalk can be more reliably suppressed.

By the way, when the pitch between the nozzles in the nozzle row direction is the same, when the thickness D of the partition wall 37 is increased, the width W of the pressure chamber 20 is relatively reduced. Focusing on the ratio of the height H of the pressure chamber 20 to the width W of the pressure chamber 20, this ratio is set so as to satisfy the following equation (5).
0.7 <H / W ≦ 1.6 (5)

  FIG. 6 is a graph showing a change in the crosstalk ratio when the ratio of the height H of the pressure chamber 20 to the width W of the pressure chamber 20 is changed. The horizontal axis of the graph shown in FIG. 6 indicates H / W, and the vertical axis indicates the CT rate (see Equation (3)). In addition, square points in the graph shown in FIG. 6 indicate experimental values, and broken lines indicate approximate curves calculated from the experimental values. In the experiment, the ratio L / W of the protrusion width L to the width W of the pressure chamber 20 was set to 0.05.

  As shown in FIG. 6, it can be seen that the crosstalk rate exceeds 40% when H / W is larger than 1.6. As described above, it is desirable that the crosstalk rate be suppressed to 40% or less. Similarly to H / D, H / W need not have a margin for the crosstalk rate. For this reason, the upper limit value of H / W is calculated based on a crosstalk rate of 40%.

  Further, as shown in FIG. 6, it can be understood that the crosstalk rate tends to be improved as the H / W becomes smaller. However, when H / W is 0.7 or less, the volume of the pressure chamber 20 is decreased, and it has been experimentally found that the amount of ink ejected from the nozzles 23 per unit time, that is, the ink ejection efficiency deteriorates. It was. For this reason, it is not desirable to set H / W to 0.7 or less.

  That is, in addition to the above formulas (1) and (4), the ratio of the height H of the pressure chamber 20 to the width W of the pressure chamber 20 is set so as to satisfy the formula (5). Crosstalk can be more reliably suppressed while ensuring sufficiently.

  In each of the above embodiments, the so-called flexural vibration type piezoelectric element 18 is exemplified as the pressure generating means. However, the present invention is not limited to this, and for example, a so-called longitudinal vibration type piezoelectric element can be employed. In addition, in a configuration that employs pressure generating means such as a heating element that generates pressure fluctuations by generating bubbles due to heat generation, or an electrostatic actuator that generates pressure fluctuations by displacing the working surface of the pressure chamber by electrostatic force Also, the present invention can be applied.

  The present invention also provides a liquid ejecting head that ejects liquid such as ink from nozzles by displacing a plurality of pressure chambers by partition walls, and displacing an operation surface that seals the opening surface of the pressure chamber by a pressure generating unit. If it is a liquid ejecting apparatus provided with this, not only a printer, but also various ink jet recording apparatuses such as a plotter, a facsimile machine, a copying machine, and liquid ejecting apparatuses other than the recording apparatus, for example, a display manufacturing apparatus, an electrode manufacturing apparatus, It can also be applied to a chip manufacturing apparatus or the like.

  DESCRIPTION OF SYMBOLS 1 ... Printer, 2 ... Recording head, 14 ... Pressure chamber board | substrate, 15 ... Nozzle formation board | substrate, 16 ... Elastic film, 18 ... Piezoelectric element, 20 ... Pressure chamber, 23 ... Nozzle, 37 ... Septum, 40 ... Adhesive

Claims (5)

A pressure chamber substrate in which a plurality of pressure chambers communicating with the nozzle are partitioned by a partition;
Pressure generating means for causing a pressure fluctuation in the liquid in the pressure chamber;
A bottom member that is bonded to the pressure chamber substrate by an adhesive and defines a bottom portion of the pressure chamber;
A liquid ejecting head that ejects a liquid having a compressibility higher than the compressibility of water from the nozzle by causing the pressure generating unit to drive and generate a pressure fluctuation in the pressure chamber,
In the pressure chamber juxtaposing direction, the width of the pressure chamber is W, the width of the partition wall is D, and the partition wall and the bottom member are leaked to the pressure chamber side from between the lower end portion of the partition wall and the bottom member. The width in the pressure chamber juxtaposition direction of the adhesive in a solidified state at the corners to be partitioned is L,
In the stacking direction of the pressure chamber substrate and the bottom member, when the height of the pressure chamber is H,
0.05 ≦ L / W ≦ 0.3
And 3.8 <H / D ≦ 9.0
A liquid jet head characterized by satisfying: 0.7 <H / W ≦ 1.6
The liquid ejecting head according to claim 1, wherein: The liquid is an organic solvent as a solvent,
3. The liquid jet head according to claim 1, wherein a swelling ratio of the adhesive in a state of being immersed in the liquid for 100 hours in an environment of 40 ° C. is 10% or less.   The liquid ejecting head according to claim 3, wherein the adhesive is an epoxy adhesive in which silica is blended in an amount of 5 wt% to 10 wt%.   A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1.

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