JP7401181B2 - Liquid ejection head, recording device using the same, and method for manufacturing the liquid ejection head - Google Patents

Description

The present disclosure relates to a liquid ejection head, a recording device using the same, and a method of manufacturing the liquid ejection head.

2. Description of the Related Art Conventionally, as a printing head, for example, a liquid ejection head that performs various kinds of printing by ejecting liquid onto a recording medium is known. In the liquid ejection head, for example, a large number of ejection holes for ejecting liquid are arranged two-dimensionally. Printing is performed by landing liquid ejected from each ejection hole in a line on a recording medium (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2009-143168

The liquid ejection head of the present disclosure includes a flow path member having a plurality of ejection holes, a plurality of pressurizing chambers connected to the plurality of ejection holes, a plurality of common flow paths, and at least one dummy common flow path; A liquid ejection head including a plurality of pressurizing parts that pressurize a plurality of pressurizing chambers, wherein the plurality of common channels have a plurality of first common channels and a plurality of second common channels. The plurality of first common channels and the plurality of second common channels are arranged such that the plurality of first common channels overlap on the plurality of second common channels. The plurality of pressurizing chambers extend along the first direction and are arranged in a second direction that intersects the first direction, and the area where the plurality of pressurizing chambers are arranged is referred to as the first area. If the direction opposite to the first direction is a third direction, then each of the plurality of common channels has a length extending from an end in the first direction to an end in the third direction in the first region. The at least one dummy common flow path extends along the first direction and has a length extending from the end in the first direction to the end in the third direction in the first region. The flow path member includes a plurality of plates, and the plate includes a plurality of first holes that become a part of the pressurizing chamber, and a plurality of first common flow paths or the plurality of first common flow paths. A plurality of second holes that become part of the plurality of second common channels and at least one third hole that becomes part of the dummy common channel are arranged, when the plate is viewed from above. The plurality of second holes, like the common flow path, each extend along the first direction and are arranged in line in the second direction, and the plurality of first holes If the arranged region is a second region, each of the plurality of second holes has a length extending from an end in the first direction to an end in the third direction in the second region, and At least one third hole extends along the first direction similarly to the dummy common flow path, and has a length extending from the end in the first direction to the end in the third direction in the second region. The plurality of first holes constitute a plurality of first hole rows in which the plurality of first holes are arranged side by side in the first direction, and the plurality of first holes constitute a plurality of first hole rows arranged in line in the first direction. Among them, at least a portion of the first holes that are not arranged between the second holes that are arranged to overlap vertically and are arranged in line in the second direction are It is arranged between the second hole and the third hole which are arranged in two directions .

Furthermore, the recording apparatus of the present disclosure includes the liquid ejection head, a conveyance section that conveys a recording medium to the liquid ejection head, and a control section that controls the liquid ejection head.

A method of manufacturing a liquid ejection head according to the present disclosure provides a flow path member having a plurality of ejection holes, a plurality of pressurizing chambers connected to the plurality of ejection holes, a plurality of common channels, and at least one dummy common channel. A method of manufacturing a liquid ejection head comprising: the plurality of common channels having a plurality of first common channels and a plurality of second common channels; The second common flow path is such that the plurality of first common flow paths are arranged so as to overlap with the plurality of second common flow paths, and each of them extends along the first direction, The pressurizing chambers are arranged in a line in a second direction that intersects the first direction, and a region in which the plurality of pressurizing chambers are arranged is defined as a first region, and a direction opposite to the first direction is defined as a third region. In terms of direction, each of the plurality of common channels has a length extending from an end in the first direction to an end in the third direction in the first region, and the at least one dummy common channel extends along the first direction and has a length extending from the end in the first direction to the end in the third direction in the first region, and the channel member is formed in the etching process. the plurality of first holes forming a part of the plurality of pressurizing chambers, the plurality of first common flow holes formed in the plate in the etching step; When the plate is viewed from above, the arrangement of the plurality of second holes that become a part of the channel or the plurality of second common flow channels, and the at least one third hole that becomes a part of the dummy common flow channel is arranged such that when the plate is viewed from above, , the plurality of second holes, like the common flow path, each extend along the first direction and are arranged in line in the second direction, and the plurality of first holes are arranged. If the area where the area is formed is a second area, each of the plurality of second holes has a length extending from an end in the first direction to an end in the third direction in the second area, and the at least One third hole extends along the first direction similarly to the dummy common flow path, and has a length extending from the end in the first direction to the end in the third direction in the second region. The plurality of first holes constitute a plurality of first hole rows in which the plurality of first holes are arranged side by side in the first direction, and the plurality of first holes are Among them, at least a part of the first holes that are not arranged between the second holes that are arranged to overlap vertically and are arranged in line in the second direction are This arrangement is arranged between the second hole and the third hole that are arranged side by side in the direction .

(a) is a side view of a recording device including a liquid ejection head according to an embodiment of the present disclosure, and (b) is a plan view. (a) is a plan view of the head main body which is a main part of the liquid ejection head of FIG. 1, and (b) is a plan view from (a) with the second flow path member removed. It is an enlarged plan view of a part of FIG.2(b). It is an enlarged plan view of a part of FIG.2(b). (a) is a plan view of a plate constituting a part of a channel member, and (b) is an enlarged plan view of a part of (a). (a) is a plan view of another plate constituting a part of the channel member, and (b) is an enlarged plan view of a part of (a). (a) is a schematic partial vertical cross-sectional view of the head body, and (b) is a vertical cross-sectional view of other parts of the head body, and is a vertical cross-sectional view of a plate that constitutes a part of the flow path member. be. FIG. 2 is an arrangement of the first holes of the present disclosure.

FIG. 1A is a schematic side view of a color inkjet printer 1 (hereinafter sometimes simply referred to as a printer), which is a recording device including a liquid ejection head 2 according to an embodiment of the present disclosure. (b) is a schematic plan view. The printer 1 includes a liquid ejection head 2 that ejects liquid, and a movable part that moves a recording medium relative to the liquid ejection head 2. In the printer 1, the movable parts include the conveyance rollers 82A, 82B, 82C, and 82D, and the motors that drive them. The movable portion transports the printing paper P, which is a recording medium, from the transport roller 82A to the transport roller 82C. The control unit 88 controls the liquid ejection head 2 to eject the liquid toward the printing paper P based on print data such as images and characters, and causes the liquid to land on the printing paper P. Recording such as printing is performed on the printing paper P.

In this embodiment, the liquid ejection head 2 is fixed to the printer 1, and the printer 1 is a so-called line printer. Another embodiment of the recording apparatus includes an operation in which the liquid ejection head 2 is moved back and forth in a direction that intersects with the conveying direction of the printing paper P, for example, in a direction that is substantially orthogonal to the direction, and ejects the liquid along the way. For example, there is a so-called serial printer that alternately carries out printing paper P and transporting the printing paper P. In the serial printer, the movable part includes a carriage on which the liquid ejection head 2 is mounted, and a motor that reciprocates the carriage in a direction intersecting the conveyance direction of the printing paper P. The movable part may include a roller that conveys the printing paper P, a motor that drives the roller, and the like.

Four flat head mounting frames 70 (hereinafter sometimes simply referred to as frames) are fixed to the printer 1 so as to be substantially parallel to the printing paper P. Each frame 70 is provided with five holes (not shown), and five liquid ejection heads 2 are mounted in each hole. Five liquid ejection heads 2 mounted on one frame 70 constitute one head group 72. The printer 1 has four head groups 72, and a total of 20 liquid ejection heads 2 are mounted thereon.

The liquid ejection head 2 mounted on the frame 70 has a portion that ejects liquid facing the printing paper P. The distance between the liquid ejection head 2 and the printing paper P is, for example, about 0.5 to 20 mm.

The 20 liquid ejection heads 2 may be directly connected to the control section 88, or may be connected through a distribution section that distributes print data therebetween. The distribution unit may distribute the print data sent from the control unit 88 to the 20 liquid ejection heads 2, for example. Further, for example, by using four distribution sections corresponding to the four head groups 72, each distribution section receives the print data sent from the control section 88 to the four distribution sections. The liquid may be distributed to one liquid ejection head 2.

The liquid ejection head 2 has an elongated shape that is elongated in the direction from the front to the back in FIG. 1(a) and in the vertical direction in FIG. 1(b). In one head group 72, the three liquid ejection heads 2 are lined up in a direction that intersects the conveyance direction of the printing paper P, for example, in a direction that is almost perpendicular to the conveyance direction, and the other two liquid ejection heads 2 One each is lined up between the three liquid ejection heads 2 at positions shifted along the direction. In other words, in one head group 72, the liquid ejection heads 2 are arranged in a staggered manner. The liquid ejection heads 2 are arranged so that the range that can be printed by each liquid ejection head 2 is connected in the width direction of the printing paper P, that is, in a direction intersecting the conveyance direction of the printing paper P, or so that the edges thereof overlap. This makes it possible to print without gaps in the width direction of the printing paper P.

The four head groups 72 are arranged along the conveyance direction of the printing paper P. Each liquid ejection head 2 is supplied with liquid, such as ink, from a liquid supply tank (not shown). The liquid ejection heads 2 belonging to one head group 72 are supplied with ink of the same color, and the four head groups 72 can print with four colors of ink. The colors of ink ejected from each head group 72 are, for example, magenta (M), yellow (Y), cyan (C), and black (K). If such ink is controlled and printed by the control unit 88, a color image can be printed.

The viscosity of the liquid stored in the liquid supply tank for printing is, for example, 5 mPa·s or more and 15 mPa·s or less. The liquid supply tank may be provided with an agitation unit that agitates the liquid so that the viscosity of the contained liquid becomes high and the components are less likely to settle.

In the printer 1, liquid that has not been ejected by the liquid ejection head 2 may be collected from the liquid ejection head 2. The recovered liquid may be returned to a liquid supply tank that supplies liquid to the liquid ejection head 2, or may be stored in a liquid recovery tank. The liquid stored in the liquid recovery tank can be used for printing by passing it through a filter or adjusting its viscosity, if necessary.

The number of liquid ejection heads 2 mounted on the printer 1 may be one as long as the printable range is printed in a single color with one liquid ejection head 2. The number of liquid ejection heads 2 included in the head group 72 and the number of head groups 72 can be changed as appropriate depending on the object to be printed and printing conditions. For example, the number of head groups 72 may be increased to print in more colors. Furthermore, if a plurality of head groups 72 that print in the same color are arranged and print alternately in the transport direction, the transport speed can be increased even if liquid ejection heads 2 with the same performance are used. Thereby, the printing area per hour can be increased. Alternatively, a plurality of head groups 72 that print in the same color may be prepared and arranged so as to be shifted in a direction intersecting the transport direction to increase the resolution in the width direction of the printing paper P.

Furthermore, in addition to printing colored ink, a liquid such as a coating agent may be printed uniformly or in a pattern using the liquid ejection head 2 in order to treat the surface of the printing paper P. . As the coating agent, for example, when using a recording medium that is difficult for liquid to penetrate, a coating agent that forms a liquid-receiving layer so that the liquid can be easily fixed can be used. In addition, when using a recording medium that is easily penetrated by liquid, coating agents are used to suppress liquid penetration to prevent the liquid from bleeding too much or from mixing with other liquids that land next to it. Anything that forms a layer can be used. In addition to being printed by the liquid ejection head 2, the coating agent may be uniformly applied by the application section 75 controlled by the control section 88.

The printer 1 prints on printing paper P, which is a recording medium. The printing paper P is wound around the paper feeding roller 80A, and the printing paper P sent out from the paper feeding roller 80A passes under the liquid ejection head 2 mounted on the frame 70. Thereafter, it passes between two transport rollers 82C and is finally collected by collection roller 80B. When printing, the printing paper P is transported at a constant speed by rotating the transport roller 82C, and printed by the liquid ejection head 2.

Next, details of the printer 1 will be explained in the order in which the printing paper P is conveyed. The printing paper P sent out from the paper feed roller 80A passes between the two conveyance rollers 82A, and then passes under the coating section 75. The coating section 75 coats the printing paper P with the above-described coating agent.

The printing paper P then enters a head chamber 74 that houses the frame 7 on which the liquid ejection head 2 is mounted. The head chamber 74 is connected to the outside at a portion such as a portion where the printing paper P enters and exits, but is generally a space isolated from the outside. In the head chamber 74, control factors such as temperature, humidity, and atmospheric pressure are controlled by a control unit 88 and the like as necessary. In the head chamber 74, the influence of disturbances can be reduced compared to the outside where the printer 1 is installed, so the range of variation of the above-mentioned control factors can be made narrower than outside.

Five conveyance rollers 82B are arranged in the head chamber 74, and the printing paper P is conveyed on the conveyance rollers 82B. The five conveyance rollers 82B are arranged so that their centers are convex in the direction in which the frame 70 is arranged when viewed from the side. This results in 5
The printing paper P transported over the transport rollers 82B has an arc shape when viewed from the side, and by applying tension to the printing paper P, the printing paper P between the transport rollers 82B becomes flat. It is stretched so that One frame 70 is arranged between the two transport rollers 82B. The angle at which each frame 70 is installed is changed little by little so that it is parallel to the printing paper P conveyed underneath.

The printing paper P that has come out of the head chamber 74 passes between the two transport rollers 82C, passes through the drying section 76, passes between the two transport rollers 82D, and is collected by the collection roller 80B. The conveyance speed of the printing paper P is, for example, 100 to 200 m/min. Each roller may be controlled by the control unit 88 or may be manually operated by a person.

By drying in the drying section 76, printing sheets P wound up overlapping each other are less likely to adhere to each other and undried liquid is less likely to rub against each other on the collecting roller 80B. In order to print at high speed, it is also necessary to dry quickly. In order to speed up the drying, the drying section 76 may sequentially dry by a plurality of drying methods, or may dry by using a plurality of drying methods in combination. Drying methods used in such cases include, for example, blowing hot air, irradiating with infrared rays, and contacting heated rollers. When infrared rays are irradiated, infrared rays in a specific frequency range may be applied so as to reduce damage to the printing paper P and speed up drying. When the printing paper P is brought into contact with a heated roller, the time for heat to be transmitted may be lengthened by conveying the printing paper P along the cylindrical surface of the roller. The range of conveyance is preferably 1/4 turn or more, and more preferably 1/2 turn or more. When printing UV curable ink or the like, a UV irradiation light source may be provided instead of the drying section 76 or in addition to the drying section 76. A UV radiation source may be placed between each frame 70.

The printing paper P, on which the printed liquid has been dried or hardened so that it can be collected by the collection roller 80B, is imaged by the imaging unit 77 to check the printing state. The printing state may be checked by printing a test pattern or by printing print data to be printed. The imaging may be performed while conveying the printing paper P, that is, while printing other parts of the printing paper P, or may be performed while the conveyance is stopped.

The captured image data is evaluated by the control unit 88 to see if there are any unprinted parts or parts with low printing accuracy. Specifically, check whether there are any pixels that are not printed because the liquid was not ejected, or whether the ejected amount, ejection speed, and ejection direction of the ejected liquid deviate from the target values, or if the liquid is in flight. It is evaluated whether the landing position of the liquid is shifted or the spread of pixels after landing becomes smaller or larger due to the influence of gas flow or the like.

When the control unit 88 detects a deviation of more than a set threshold value in the imaging data, it may notify the result. Further, if printing is in progress, there is no need to stop printing or restart printing that is scheduled to be restarted.

Further, the control unit 88 may modify the print data so as to correct the deviation detected from the imaging data, and cause the liquid ejection head 2 to eject the liquid based on the modified print data. Specifically, when there is a pixel that is not printed, a pixel that is small in size, or a pixel with low density, the control unit 88 increases the amount of liquid that lands around that pixel with respect to the original print data. Print data may be created and printed. Similarly, if the size of a pixel is large or the density of a pixel is high, print data may be created in which the amount of liquid that lands around the pixel is reduced. If the landing position shifts in a certain direction, create print data that reduces the amount of liquid that lands around the area in the direction of the deviation, and increases the amount of liquid that lands around the area in the opposite direction. Good too. The range in which the print data is modified may be not only the pixels adjacent to the pixel in which the misalignment has been detected, but also a wider range.

The printer 1 may include a cleaning section that cleans the liquid ejection head 2. The cleaning section performs cleaning by, for example, wiping or capping. In wiping, for example, a flexible wiper is used to rub the surface of the part from which the liquid is ejected, for example, the nozzle surface 4-2, which will be described later, to remove the liquid adhering to that surface. Washing with capping is performed, for example, as follows. By placing a cap so as to cover the part from which liquid is to be discharged, for example, the nozzle surface 4-2 (described later) (this is called capping), the nozzle surface 4-2 and the cap are almost sealed and a space is created. . By repeatedly discharging the liquid in such a state, the liquid whose viscosity is higher than the standard state, foreign matter, etc. that are clogged in the discharge hole 8 are removed. By capping, the liquid being cleaned is less likely to scatter onto the printer 1, and the liquid is less likely to adhere to the printing paper P and conveyance mechanisms such as rollers. The nozzle surface 4-2 that has been cleaned may be further wiped. Wiping and cleaning by capping may be performed by a person manually operating the wiper or cap attached to the printer 1, or may be performed automatically by the control unit 88.

In addition to printing paper P, the recording medium may be a roll of cloth or the like. Further, instead of directly conveying the printing paper P, the printer 1 may directly convey a conveyor belt, and place the recording medium on the conveyor belt and convey it. In this way, sheets of paper, cut cloth, wood, tiles, etc. can be used as recording media. Furthermore, a wiring pattern of an electronic device or the like may be printed by ejecting a liquid containing conductive particles from the liquid ejection head 2. Furthermore, a chemical agent may be produced by ejecting a predetermined amount of a liquid chemical agent or a liquid containing a chemical agent from the liquid ejecting head 2 toward a reaction container or the like to cause a reaction.

Alternatively, a position sensor, a speed sensor, a temperature sensor, etc. may be attached to the printer 1, and the control unit 88 may control each part of the printer 1 according to the status of each part of the printer 1 as determined from information from each sensor. . For example, the temperature of the liquid ejection head 2, the temperature of the liquid in the liquid supply tank that supplies liquid to the liquid ejection head 2, the pressure that the liquid in the liquid supply tank applies to the liquid ejection head 2, etc. If the ejection characteristics, that is, the ejection amount, ejection speed, etc., are affected, the drive signal for ejecting the liquid may be changed in accordance with such information.

Next, a liquid ejection head 2 according to an embodiment of the present disclosure will be described. FIG. 2(a) is a plan view showing a head main body 2a, which is a main part of the liquid ejection head 2 shown in FIG. FIG. 2(b) is a plan view of the head main body 2a with the second flow path member 6 removed. FIG. 3 is an enlarged plan view of the head main body 2a in the range indicated by the dashed line in FIG. 2(b). FIG. 4 is an enlarged plan view of the head main body 2a in the range indicated by the dashed line in FIG. 5(a) is a plan view of a plate 4e constituting a part of the channel member 4, and FIG. 5(b) is an enlarged plan view of a part of FIG. 5(a). 6(a) is a plan view of a plate 4i constituting a part of the channel member 4, and FIG. 6(b) is an enlarged plan view of a part of FIG. 6(a). FIG. 7(a) is a schematic partial longitudinal sectional view of the head main body 2a. In FIG. 7A, in order to show the state in which the channels are connected, channels that do not actually exist in the same longitudinal section are drawn as if they exist in the same longitudinal section. More specifically, it is a longitudinal section of a different part from the plate 4g and above and from the plate 4h. FIG. 7(b) is a longitudinal sectional view of another portion of the head main body 2a. However, FIG. 7 (b) also depicts a signal transmission section 60 that is not depicted in FIG. 2(a). FIG. 7(c) is a longitudinal cross-sectional view of a plate 4e that constitutes a part of the flow path member 4.

Each figure is drawn as follows to make the drawings easier to understand. In FIGS. 2 to 4, channels that are below other objects and should be drawn with broken lines are drawn with solid lines. In FIG. 4, the pressurizing chamber main body 10b, the first flow path 12, and the like are omitted on the left side of the center two-dot chain line that divides the figure into left and right parts. Only the individual electrodes 44 and the connection electrodes 46 corresponding to the four pressurizing chambers 10 in the upper left part of the figure are depicted.

The liquid ejection head 2 may include a housing, a driver IC, a wiring board, etc. in addition to the head main body 2a. The head body 2a also includes a first flow path member 4, a second flow path member 6 that supplies liquid to the first flow path member 4, and a piezoelectric actuator in which a displacement element 50 serving as a pressurizing section is built. A substrate 40 is included. The head main body 2a has a flat plate shape that is long in one direction, and this direction is sometimes referred to as a longitudinal direction. Further, the second channel member 6 plays the role of a support member that supports the structure of the head main body 2a, and the head main body 2a is fixed to the frame 70 at each of both longitudinal ends of the second channel member 6. be done.

The first channel member 4 constituting the head main body 2a has a flat plate shape, and has a thickness of about 0.5 to 2 mm. On a pressurizing chamber surface 4-1, which is one surface of the first flow path member 4, a large number of pressurizing chambers 10 are arranged side by side in the plane direction. On the discharge hole surface 4-2 of the first flow path member 4, which is the surface opposite to the pressurized chamber surface 4-1, a large number of discharge holes 8 through which liquid is discharged are arranged side by side in the plane direction. . The discharge holes 8 are each connected to a pressurizing chamber 10. In the following description, it will be assumed that the pressurizing chamber surface 4-1 is located above the discharge hole surface 4-2.

A plurality of first common channels 20 and a plurality of second common channels 22 are arranged in the first channel member 4 so as to extend along the first direction. Below, the first common flow path 20 and the second common flow path 22 may be collectively referred to as a common flow path. The first common flow path 20 and the second common flow path 22 are arranged to overlap. A direction intersecting the first direction is defined as a second direction. There are eight first common channels 20 and eight second common channels 22, and they are arranged in line in the second direction. Note that the first direction is the same direction as the longitudinal direction of the head main body 2a. Further, a direction opposite to the first direction is defined as a third direction, and a direction opposite to the second direction is defined as a fourth direction. In some of the figures, the first to fourth directions are indicated by D1 to D4.

Along both sides of the first common flow path 20 and the second common flow path 22, the pressurization chamber 10 is connected to the first common flow path 20 and the second common flow path 22, and the pressurization chamber 10 is connected to the pressurization chamber 10. The discharge holes 8 are lined up. The pressurizing chambers 10 connected to the first common flow path 20 and the second common flow path 22 constitute four pressurizing chamber rows 11A, two rows on each side of the common flow path, and four rows on both sides. There is. Further, the discharge holes 8 connected to the first common flow path 20 and the second common flow path 22 constitute four discharge hole rows 9A, two rows each on one side of the common flow path, and four rows on both sides. There is. Since there are eight first common channels 20 and eight second common channels 22, there are 32 pressurizing chamber rows 11A in total, and 32 discharge hole rows 9A in total.

The first common flow path 20 and the four rows of pressurizing chambers 10 lined up on both sides thereof are connected via the first flow path 12. The second common flow path 22 and the four rows of pressurizing chambers 10 lined up on both sides thereof are connected via the second flow path 14.

With the above configuration, in the first flow path member 4, the liquid supplied to the first common flow path 20 flows into the pressurizing chambers 10 lined up along the first common flow path 20. A part of the liquid that has flowed into the pressurizing chamber 10 is discharged from the discharge hole 8, and the other part flows into the second common flow path 22, which is arranged to overlap with the first common flow path 20, and It is discharged from the channel member 4 to the outside. Note that, including the explanation given below, the flow of liquid supply and recovery may be reversed.

The first common flow path 20 is arranged so as to overlap the second common flow path 22. The first common flow path 20 is located outside the first flow path member 4 with openings 20b disposed at both ends in the first direction and the third direction, outside the range where the first flow path 12 is connected. It is open to The second common flow path 22 has ends in both the first direction and the third direction outside the range where the second flow path 14 is connected and outside the opening 20b of the first common flow path 20. The arranged opening 22b opens to the outside of the first flow path member 4. Space efficiency is improved because the opening 22b of the second common flow path 22 located on the lower side is located outside the opening 20b of the first common flow path 20 located on the upper side. Note that the entire second common channel main body 22a excluding both ends is arranged below the entire first common channel main body 20a excluding both ends.

Almost the same amount of liquid is supplied from the opening 20a on the first direction side and the opening 20a on the third direction side of the first common flow path 20, and flows toward the center of the first common flow path 20. When the amount of liquid discharged from the discharge holes 8 connected to one first common flow path 20 and one second common flow path 22 is approximately constant regardless of the location, the flow in the first common flow path 20 is , becomes slower toward the center, reaching 0 (zero) approximately at the center. The flow in the second common flow path 22 is opposite to this, and is 0 (zero) approximately at the center, and the flow becomes faster toward the outside.

Since the liquid ejection head 2 records various things, the amount of liquid ejected from the ejection holes 8 connected to one first common flow path 20 and one second common flow path 22 has various distributions. Become. When the discharge amount from the discharge hole 8 on the first direction side is large, the place where the flow becomes 0 (zero) is on the first direction side with respect to the center. Conversely, when the discharge amount from the discharge holes 8 on the third direction side is large, the location where the flow becomes 0 (zero) is on the third direction side with respect to the center. In this way, as the discharge distribution changes depending on what is to be recorded, the location where the flow is 0 (zero) shifts. As a result, even if the flow becomes 0 (zero) and the liquid stagnates at a certain moment, the stagnation at that location will be resolved by changing the discharge distribution, so the liquid will continue to stagnate in the same place. This makes it difficult for pigments to settle or for liquids to stick together.

The pressure applied to the first common flow path 20 side portion of the first flow path 12 connected to the first common flow path 20 is due to pressure loss. It changes depending on the position (mainly the position in the first direction). The pressure applied to the part on the second flow path 14 side that is connected to the second common flow path 22 is affected by pressure loss, and the pressure applied to the part on the second flow path 14 side that is connected to the second common flow path 22 is position in one direction). If the pressure of the liquid in one discharge hole 8 is made approximately 0 (zero), the above-mentioned pressure change changes symmetrically, so that the pressure of the liquid in all discharge holes 8 can be made approximately 0 (zero).

The lower surface of the first common flow path 20 is a damper 28A. The surface of the damper 28A opposite to the surface facing the first common flow path 20 faces the damper chamber 29A. The damper chamber 29A contains gas such as air, and its volume changes depending on the pressure applied from the first common channel 20. The damper 28A can vibrate by changing the volume of the damper chamber 29A, and by attenuating the vibration, it is possible to attenuate pressure fluctuations occurring in the first common flow path 20. By providing the damper 28A, pressure fluctuations such as resonance of the liquid in the first common flow path 20 can be reduced.

The lower surface of the second common flow path 22 is a damper 28B. The surface of the damper 28B opposite to the surface facing the second common flow path 22 faces the damper chamber 29B. As in the case of the first common flow path, by providing the damper 28B, pressure fluctuations such as liquid resonance in the second common flow path 22 can be reduced.

In one discharge hole row 9A, the discharge holes 8 are arranged at intervals of 50 dpi (about 25.4 mm/50). There are 32 ejection hole rows 9A, and the ejection holes 8 included therein are arranged offset from each other in the first direction, so that the ejection holes 8 are arranged at intervals of 1600 dpi overall.

More specifically, in FIG. 3, when the discharge holes 8 are projected in a direction perpendicular to the first direction, 32 discharge holes 8 are projected within the range of the virtual straight line R, and each discharge hole 8 is projected within the virtual straight line R. are arranged at intervals of 1200 dpi. Thereby, if the printing paper P is conveyed in a direction perpendicular to the virtual straight line R and printed, printing can be performed at a resolution of 1200 dpi.

The second flow path member 6 is joined to the pressure chamber surface 4-1 of the first flow path member 4, and is connected to a first integrated flow path 24 that supplies liquid to the first common flow path 20 and a second common flow path 24 that supplies liquid to the first common flow path 20. It has a second integrated flow path 26 for recovering the liquid in the flow path 22. The thickness of the second flow path member 6 is thicker than the first flow path member 4, and is about 5 to 30 mm.

The second flow path member 6 is joined to the pressure chamber surface 4-1 of the first flow path member 4 in a region to which the piezoelectric actuator substrate 40 is not connected. More specifically, they are joined so as to surround the piezoelectric actuator substrate 40. By doing so, it is possible to suppress a portion of the discharged liquid from adhering to the piezoelectric actuator substrate 40 in the form of mist. Furthermore, since the first flow path member 4 is fixed at its outer periphery so as to surround the piezoelectric actuator substrate 40, the resonance that occurs when the first flow path member 4 vibrates as the displacement element 50 is driven is reduced. can.

An opening 24b that opens to the upper surface of the second flow path member 6 is arranged at the end of the first integrated flow path 24 in the third direction. The first integrated flow path 24 branches into two in the middle, one side is connected to the opening 20b of the first common flow path 20 on the third direction side, and the other side is connected to the first common flow path on the first direction side. 20 is connected to the opening 20b. An opening 26b that opens on the upper surface of the second flow path member 6 is arranged at the end of the second integrated flow path 26 in the first direction. The second integrated flow path 26 branches into two in the middle, one side is connected to the opening 22b of the second common flow path 22 on the first direction side, and the other side is connected to the first common flow path on the third direction side. 22 is connected to the opening 22b. When printing, liquid is supplied from the outside to the opening 24b of the first integrated flow path 24, and the undischarged liquid is collected from the opening 26b of the second integrated flow path 26.

Further, the second flow path member 6 is provided with a through hole 6 a that vertically passes through the second flow path member 6 . A signal transmission section 60 such as an FPC (Flexible Printed Circuit) that transmits a drive signal for driving the piezoelectric actuator substrate 40 is passed through the through hole 6a.

By arranging the first integrated flow path 24 in a second flow path member 6 that is separate from the first flow path member 4 and that is thicker than the first flow path member 4, the cross-sectional area of the first integrated flow path 24 can be increased. As a result, the difference in pressure loss due to the difference in the position where the first integrated flow path 24 and the first common flow path 20 are connected can be reduced. The flow path resistance of the first integrated flow path 24 is preferably 1/100 or less of that of the first common flow path 20. Here, the flow path resistance of the first integrated flow path 24 is more accurately the flow path resistance of the range of the first integrated flow path 24 that is connected to the first common flow path 20.

By arranging the second integrated flow path 26 in a second flow path member 6 that is separate from the first flow path member 4 and is thicker than the first flow path member 4, the cross-sectional area of the second integrated flow path 26 can be increased. As a result, the difference in pressure loss due to the difference in the position where the second integrated flow path 26 and the second common flow path 22 are connected can be reduced. The flow path resistance of the second integrated flow path 26 is preferably 1/100 or less of that of the second common flow path 22. Here, the flow path resistance of the second integrated flow path 26 is more accurately the flow path resistance of the range of the second integrated flow path 26 that is connected to the second common flow path 22 .

The first integrated flow path 24 is arranged at one end of the second flow path member 6 in the width direction, and the second integrated flow path 26 is arranged at the other end of the second flow path member 6 in the width direction, The structure is such that each flow path faces the first flow path member 4 side and is connected to the first common flow path 20 and the second common flow path 22, respectively. With such a structure, the cross-sectional area of the first integrated flow path 24 and the second integrated flow path 26 can be increased, and the flow path resistance can be reduced. Moreover, by adopting such a structure, the outer periphery of the first flow path member 4 is fixed by the second flow path member 6, so that the rigidity can be increased. Furthermore, with such a structure, the through hole 6a through which the signal transmission section 60 passes can be provided.

A groove that becomes the first integrated flow path 24 and a groove that becomes the second integrated flow path 26 are arranged on the lower surface of the second flow path member 6. A portion of the lower surface of the groove that becomes the first integrated flow path 24 of the second flow path member 6 is closed by the upper surface of the flow path member 4, and the other portion of the lower surface is arranged on the upper surface of the flow path member 4. By connecting with the opening 20a of the first common flow path 20, which is located in the first common flow path 20, a first integrated flow path 24 is formed. A portion of the lower surface of the groove that becomes the second integrated flow path 26 of the second flow path member 6 is closed by the upper surface of the flow path member 4, and the other portion of the lower surface is arranged on the upper surface of the flow path member 4. By connecting with the opening 22a of the second common flow path 22, which is present, the second integrated flow path 26 is formed.

A damper may be provided in the first integrated flow path 24 and the second integrated flow path 26 to stabilize the supply or discharge of the liquid against fluctuations in the amount of liquid discharged. Furthermore, by providing a filter inside the first integrated flow path 24 and the second integrated flow path 26 and between the first common flow path 20 or the second common flow path 22, foreign substances and air bubbles can be It may be made difficult to enter the channel member 4.

The upper surface of the second flow path member 6 is covered with a metal casing or the like. The signal transmission section 60 is electrically connected to, for example, a wiring board housed in a housing. The wiring board and the control section 88 are electrically connected by a cable or the like. A driver IC for driving the mutant element 50 may be mounted in the signal transmission section 60. By bringing the driver IC into contact with a metal casing or a member that facilitates heat transfer to the casing, heat generated by the driver IC can be released to the outside.

A piezoelectric actuator substrate 40 including displacement elements 50 is bonded to the pressure chamber surface 4-1, which is the upper surface of the first flow path member 4, so that each displacement element 50 is positioned above the pressure chamber 10. It is located. The piezoelectric actuator substrate 40 occupies an area having approximately the same shape as the pressurizing chamber group constituted by the pressurizing chambers 10 . Further, the opening of each pressurizing chamber 10 is closed by joining the piezoelectric actuator substrate 40 to the pressurizing chamber surface 4-1 of the flow path member 4. The piezoelectric actuator substrate 40 has a rectangular shape that is elongated in the same direction as the head main body 2a.

A signal transmission section 60 that supplies signals to each displacement element 50 is connected to the piezoelectric actuator substrate 40 . The second channel member 6 has a through hole 6a extending vertically through the center thereof, and the signal transmitting section 60 is electrically connected to the control section 88 through the through hole 6a. The signal transmission section 60 has a shape extending in the lateral direction from one long side end of the piezoelectric actuator substrate 40 toward the other long side end, and the wiring arranged in the signal transmission section 60 is shaped so as to extend in the lateral direction. By extending along the wires and arranging them in the longitudinal direction, the distance between the wires can be increased.

Individual electrodes 44 are arranged at positions facing each pressurizing chamber 10 on the upper surface of the piezoelectric actuator substrate 40 .

The channel member 4 has a laminated structure in which a plurality of plates are laminated. A plate 4a is arranged on the pressure chamber surface 4-1 side of the flow path member 4, and plates 4b to 4l are stacked in order below the plate 4a. Note that the plate 4a in which holes are formed to form the side walls of the pressurizing chamber 10 is called a cavity plate 4a, and the plates 4e, f, i, and j in which holes are formed to form the side walls of the common flow path are called manifold plates 4e. , f, i, and j, and the plate 4l in which the discharge holes 8 are opened is sometimes called the nozzle plate 4l. Each plate has a number of holes and grooves formed therein. The holes and grooves can be formed, for example, by etching each plate made of metal. By setting the thickness of each plate to be approximately 10 to 300 μm, the precision in forming the holes can be increased. The plates are aligned and stacked such that the holes communicate with each other to form a flow path such as the first common flow path 20.

A pressurizing chamber main body 10a is open on the pressurizing chamber surface 4-1 of the flat flow path member 4, and a piezoelectric actuator substrate 40 is bonded to the pressurizing chamber main body 10a. Further, an opening 20 b for supplying liquid to the first common flow path 20 and an opening 22 b for recovering liquid from the second common flow path 22 are opened in the pressurizing chamber surface 4-1. A discharge hole 8 is opened in a discharge hole surface 4-2 of the flow path member 4, which is a surface opposite to the pressure chamber surface 4-1.

The structure for discharging liquid includes a pressurizing chamber 10 and a discharge hole 8. The pressurizing chamber 10 consists of a pressurizing chamber main body 10a facing the displacement element 50, and a partial channel 10b connecting the pressurizing chamber main body 10a and the discharge hole 8 . The pressurizing chamber main body 10a is formed in a cavity plate 4a, and the partial flow path 10b has holes formed in the plates 4b to 4k overlapped with each other, and a nozzle plate 4l (portions other than the discharge holes 8) are closed. It is made of peeling.

A first flow path 12 is connected to the pressurization chamber main body 10a, and the first flow path 12 is connected to a first common flow path 20. The first channel 12 includes a circular hole passing through the plate 4b, an elongated through groove extending in the planar direction through the plate 4c, and a circular hole passing through the plate 4d.

A second flow path 14 is connected to the partial flow path 10b, and the second flow path 14 is connected to a second common flow path 22. The second flow path 14 includes an individual flow path 14a that is connected to one pressurizing chamber 10, and a connecting flow path 14b that is also connected to another pressurizing chamber 10. In this embodiment, the two individual channels 14a connected to the two pressurizing chambers 10 are combined to form one connecting channel 14b, and then connected to the second common channel 22. The number of connection channels 14b connected to one second common channel 22 is plural. The number of connection channels 14b connected to one second common channel 22 is half the number of pressurizing chambers 10 connected to one second common channel 22. Space efficiency is improved by bundling the plurality of individual channels 14a into a connecting channel 14b and then connecting them to the second common channel 22. Note that the number of individual channels 14a connected to the connecting channel 14b may be three or more.

The first common channel 20 is formed by overlapping holes formed in plates 4e and 4f, and further closing the upper side with a plate 4d and the lower side with a plate 4g. The second common channel 22 is formed by overlapping holes formed in the plates 4i and 4j, and further closing the upper side with a plate 4h and the lower side with a plate 4k.

To summarize the flow of liquid, the liquid supplied to the first integrated flow path 24 passes through the first common flow path 20 and the first flow path 12 in order and enters the pressurizing chamber 10, and some of the liquid flows through the discharge hole. It is discharged from 8. The liquid that has not been ejected passes through the second flow path 14, enters the second common flow path 22, enters the second integrated flow path 26, and is discharged to the outside of the head main body 2a.

The piezoelectric actuator substrate 40 has a laminated structure consisting of two piezoelectric ceramic layers 40a and 40b that are piezoelectric bodies. These piezoelectric ceramic layers 40a and 40b each have a thickness of about 20 μm. That is, the thickness from the top surface of the piezoelectric ceramic layer 40a of the piezoelectric actuator substrate 40 to the bottom surface of the piezoelectric ceramic layer 40b is about 40 μm. The thickness ratio of the piezoelectric ceramic layer 40a and the piezoelectric ceramic layer 40b is 3:7 to 7:3, preferably 4:6 to 6:4. Both piezoelectric ceramic layers 40a and 40b extend across the plurality of pressurizing chambers 10. These piezoelectric ceramic layers 40a and 40b are made of, for example, lead zirconate titanate (PZT) based, NaNbO ₃ based, BaTiO ₃ based, (BiNa)NbO ₃ based, BiNaNb ₅ O ₁₅ based, etc., which have ferroelectric properties. Made of ceramic material.

The piezoelectric ceramic layer 40b does not have a structure sandwiched between electrodes, etc., which will be described below. That is, even when a drive signal is applied to the displacement element 50, the piezoelectric ceramic layer 40b does not substantially undergo spontaneous piezoelectric deformation, and the piezoelectric ceramic layer 40b functions as a diaphragm. Therefore, the piezoelectric ceramic layer 40b can be replaced with another non-piezoelectric ceramic layer or a metal plate. Alternatively, a metal plate may be laminated under the piezoelectric ceramic layer 40b, and both the piezoelectric ceramic layer 40b and the metal plate may be used as a diaphragm. In addition, in the case of such a structure, the metal plate can also be considered as a part of the 1st flow path member 4. Furthermore, in such a configuration, the reliability of the piezoelectric actuator substrate 40 can be increased because the piezoelectric ceramic layer 40b and the liquid do not come into direct contact.

The piezoelectric actuator substrate 40 has a common electrode 42 made of a metal material such as Ag--Pd, and individual electrodes 44 made of a metal material such as Au. The thickness of the common electrode 42 is about 2 μm, and the thickness of the individual electrodes 44 is about 1 μm.

The individual electrodes 44 are arranged at positions facing each pressurizing chamber 10 on the upper surface of the piezoelectric actuator substrate 40 . The individual electrodes 44 include an individual electrode body 44a whose planar shape is one size smaller than the pressurization chamber main body 10a and a substantially similar shape to the pressurization chamber main body 10a, and an extraction electrode drawn out from the individual electrode main body 44a. 44b. A connection electrode 46 is formed in a portion of one end of the extraction electrode 44b that is extracted outside the area facing the pressurizing chamber 10. The connection electrode 46 is made of a conductive resin containing conductive particles such as silver particles, and is formed to have a thickness of about 5 to 200 μm. Further, the connection electrode 46 is electrically connected to an electrode provided in the signal transmission section 60.

Although details will be described later, a drive signal is supplied to the individual electrodes 44 from the control section 88 through the signal transmission section 60. The drive signal is supplied at regular intervals in synchronization with the conveyance speed of the print medium P.

The common electrode 42 is formed over almost the entire surface in the area between the piezoelectric ceramic layer 40a and the piezoelectric ceramic layer 40b. That is, the common electrode 42 extends so as to cover all the pressurizing chambers 10 in the area facing the piezoelectric actuator substrate 40. The common electrode 42 includes a through conductor formed through the piezoelectric ceramic layer 40a on a common electrode surface electrode (not shown) formed on the piezoelectric ceramic layer 40a at a position avoiding the electrode group consisting of the individual electrodes 44. are connected through. Further, the common electrode 42 is grounded via a common electrode surface electrode and held at a ground potential. The common electrode surface electrode, like the individual electrodes 44, is directly or indirectly connected to the control section 88.

The portion of the piezoelectric ceramic layer 40a sandwiched between the individual electrode 44 and the common electrode 42 is polarized in the thickness direction, and becomes a displacement element 50 with a unimorph structure that is displaced when a voltage is applied to the individual electrode 44. There is. More specifically, when an electric field is applied to the piezoelectric ceramic layer 40a in the polarization direction with the individual electrodes 44 at a different potential than the common electrode 42, the part to which this electric field is applied becomes an active part that is distorted due to the piezoelectric effect. Work as. In this configuration, when the individual electrode 44 is set to a predetermined positive or negative potential with respect to the common electrode 42 by the control unit 88 so that the electric field and polarization are in the same direction, the portion of the piezoelectric ceramic layer 40a sandwiched between the electrodes (active part) contracts in the plane direction. On the other hand, since the piezoelectric ceramic layer 40b, which is an inactive layer, is not affected by the electric field, it does not shrink spontaneously and tries to restrict the deformation of the active region. As a result, a difference in strain in the polarization direction occurs between the piezoelectric ceramic layer 40a and the piezoelectric ceramic layer 40b, and the piezoelectric ceramic layer 40b is deformed so as to be convex toward the pressurizing chamber 10 (unimorph deformation).

Next, the liquid ejection operation will be explained. The displacement element 50 is driven (displaced) by a drive signal supplied to the individual electrode 44 via a driver IC or the like under control from the control unit 88 . In this embodiment, liquid can be ejected using various drive signals, but here, a so-called pull drive method will be described.

The individual electrodes 44 are set to a higher potential (hereinafter referred to as high potential) than the common electrode 42 in advance, and each time there is a discharge request, the individual electrodes 44 are once set to the same potential as the common electrode 42 (hereinafter referred to as low potential), Thereafter, the potential is set to high again at a predetermined timing. As a result, the piezoelectric ceramic layers 40a and 40b return to their original (flat) shape at the timing when the individual electrode 44 becomes low potential, and the volume of the pressurizing chamber 10 returns to its initial state (the potentials of both electrodes are different). state). As a result, negative pressure is applied to the liquid within the pressurizing chamber 10. Then, the liquid in the pressurizing chamber 10 begins to vibrate at the natural vibration period. Specifically, first, the volume of the pressurizing chamber 10 begins to increase, and the negative pressure gradually decreases. Then, the volume of the pressurized chamber 10 becomes maximum and the pressure becomes almost zero. Then, the volume of the pressurizing chamber 10 begins to decrease, and the pressure increases. Thereafter, the individual electrodes 44 are brought to a high potential at a timing when the pressure is approximately at its maximum. Then, the first vibration applied and the next vibration overlap, and greater pressure is applied to the liquid. This pressure propagates within the partial channel 10b and causes the liquid to be discharged from the discharge hole 8.

That is, droplets can be ejected by supplying the individual electrodes 44 with a pulsed drive signal that keeps the potential low for a certain period of time with a high potential as a reference. If this pulse width is set to AL (Acoustic Length), which is half the natural vibration period of the liquid in the pressurizing chamber 10, in principle, the ejection speed and amount of the liquid can be maximized. The natural vibration period of the liquid in the pressurizing chamber 10 is largely influenced by the physical properties of the liquid and the shape of the pressurizing chamber 10, but is also influenced by the physical properties of the piezoelectric actuator substrate 40 and the flow path connected to the pressurizing chamber 10. It is also influenced by the characteristics of

A factor that has a large influence on the amount of liquid discharged from each discharge hole 8 is the shape of the pressurizing chamber 10, and in particular, the shape of the partial flow path 10b has a large influence. When the cross-sectional dimension of the partial flow path 10b is large, the pressure applied to the pressurizing chamber main body 10a is easily transmitted to the discharge hole 8, and basically, the amount of liquid discharged increases and the discharge speed becomes faster. On the other hand, if the cross-sectional dimension of the partial flow path 10b is small, the pressure applied to the pressurizing chamber main body 10a will be difficult to be transmitted to the discharge hole 8, and basically, the amount of liquid discharged will be small and the discharge speed will be slow. Become . The above relationship may change depending on the drive waveform used for ejection, but even in such a case, whether or not pressure is easily transmitted to the partial flow path 10b influences the ejection characteristics.

The cross-sectional dimensions of the partial channels 10b are basically designed to be the same, but variations occur depending on the manufacturing process. Depending on the design, the variation may become noticeable. Specifically, when the liquid ejected from the partial flow path 10b whose cross-sectional dimension has increased due to variations lands on the recording medium side by side, that portion appears darker than usual. When the liquid ejected from the partial channel 10b whose cross-sectional dimension has become smaller due to variations lands on the recording medium side by side, that portion appears thinner than usual. In order to make the concentration difference less noticeable when viewed by a person, it is necessary to discharge from the partial channel 10b whose cross-sectional dimension is large due to variations, and discharge from the partial channel 10b whose cross-sectional dimension is small. You just have to make sure that the bullets don't line up and land.

The partial flow paths 10b are formed in the plates 4b to 4k, and among these, the plates 4e, f and the second common flow path 22 in which the second hole 20c, which becomes the first common flow path 20, is formed are formed. In the plates 4i and 4j in which the second holes 22c are formed, variations in the first holes 10c forming the partial channel 10b may become large.

This is thought to be because the flow of the etching solution generated when etching the plate differs between locations near and far from the second holes 20c and 22c, which have large openings. Near the second holes 20c, 22c with large openings, the flow of the etching solution is disturbed and new etching solution is easily supplied, so that etching tends to proceed and the first hole 10c tends to become large.

When the distance from the first hole 10c to the nearest second holes 20c, 22c is the distance L, the first hole 10c is connected to the first group 36 consisting of the first holes 10c with the short distance L, and the first hole 10c is It is divided into a second group 37 which is longer than the first group 36 (see FIGS. 5 and 6). In this embodiment, there are two types of distance L: L1, which is short, and L2, which is longer than L1. Although details will be described later, the first holes 10c belonging to the first group 36 and the first holes 10c belonging to the second group 37 are arranged alternately in the first direction. As a result, droplets ejected from the first hole 10c belonging to the first group 36 and droplets ejected from the first hole 10c belonging to the second group 37 alternately land on the recording medium, so that The difference becomes less noticeable.

The arrangement of the first holes 10c will be explained using FIG. 8. The arrangement of the first hole 10c described here is based on the plates 4e, f in which the second hole 20c, which becomes the first common flow path 20, is formed, and the second hole 22c, which becomes the second common flow path 22, is formed. This is the arrangement on plates 4i and j. In this embodiment, the discharge hole 8 is arranged at the same position as the first hole 10c described here, but the discharge hole 8 may be arranged at a different position from the first hole 10c. As for the arrangement at a different position, for example, it may be provided at a position different from the center of the first hole 10c within a range connected to the first hole 10c. Further, a flow path may be provided whose planar position is shifted from the same position as the first hole 10c described here to the discharge hole 8.

In FIG. 8, the first hole 10c is represented by a black circle. One of the squares in the left-right direction in FIG. 8, which is the first direction, corresponds to the resolution of the liquid ejection head 2, which is 1/1600 inch (1/1600 of 1 inch). The first holes 10c constitute a first hole row 34c in which the first holes 10c are arranged every 32/1600 inches in the first direction. The first holes 10c are arranged in the same pattern repeatedly every 32/1600 inches, and the patterns are continuous on the right and left sides of FIG. 8. However, if the first hole 10c is arranged offset from the discharge hole 8, the arrangement may be different from the above-mentioned position.

In FIG. 8, the eight common flow paths are represented by M1 to M8. For each first hole row 34c, when the first hole 10c belonging to that row belongs to the first group 36, it is written as G1, and when it belongs to the second group 37, it is written as G2.

In FIG. 8, the first hole 10c belongs to the first group 36 (G1 in FIG. 8), and the first hole 10c belongs to the second group 37 (G2 in FIG. 8) in the first direction. are arranged alternately. With this arrangement, as described above, the recording medium contains droplets ejected from the first holes 10c belonging to the first group 36 and liquid droplets ejected from the first holes 10c belonging to the second group 37. Since the droplets land alternately, the difference in shading becomes less noticeable.

The shape of the first hole 10c will be explained using FIG. 7(c). Although FIG. 7(a) shows the cross-sections of plates a to k, this is a schematic representation and is processed by etching, so the actual cross-sectional shape is as shown in FIG. 7(c). become. Etching is performed by applying a resist to the upper and lower surfaces of the plate 4e, except for the portions to be etched. In the opening portion of the resist, etching progresses in an arc shape, and the etched portion from the upper surface and the etched portion from the lower surface are connected, thereby forming the first hole 10c. In fact, even after they are connected, etching is continued so that the first hole 10c approaches a predetermined shape.

If the diameter of the first hole 10c is small with respect to the thickness T of the plate 4e, there is a possibility that the variation in the diameter of the first hole 10c becomes large. When the radius of the first hole 10c on the surface (at least one of the upper surface and the lower surface) of the plate 4e is R1, by setting R1≧2T/3, variations in the diameter of the first hole 10c can be reduced. For example, when T=150 μm, R1 may be set to 100 μm or more. When R1 is small, when etched from both sides and connected near the center of the thickness, the connected area has a thin protrusion shape, so the etching progresses between the first holes 10c. When there is a difference in direction, the extent to which the thin protrusion is etched changes greatly, and the diameter of the hole where it penetrates changes greatly. Therefore, it is preferable to set R1≧2T/3.

When the diameter of the hole in the penetrating portion, specifically, the radius of the first hole 10c at the smallest diameter position in the depth direction of the first hole 10c is R2 , R2 ≧0. By setting 9R1 , the variation in R2 can be reduced. If the protrusion near the center of the thickness described above is etched, the thickness of that portion becomes thicker, so even if there is a difference in the progress of etching, the variation in R2 can be reduced. If the diameter is larger than R1, the shape of the hole may collapse, so it is preferable that R2 ≦ R1 .

In this embodiment, many of the first holes 10c are arranged between the second holes 20c and 22c. On the other hand, at the ends in the second direction and the fourth direction, there is a first hole 10c on which second holes 20c, 22c are arranged only on one side. When the second holes 20c and 22c are located on both sides when viewed from the first hole 10c, the turbulence of the etching solution becomes larger and etching progresses more easily than when the second holes 20c and 22c are located only on one side. Become. That is, the first holes 10c at the ends in the second direction and the fourth direction may become relatively small.

Therefore, the third holes 30c, 32c are arranged so that the first hole 10c at the ends in the second direction and the fourth direction is sandwiched between the second holes 20c, 22c and the third holes 30c, 32c. do.

The third hole 30c is a hole extending in the first direction like the second hole 20c, and is the end in the second direction of the second hole 20c lined up in the second direction, and the opposite direction to the second direction. It is arranged at the end in the fourth direction. In this embodiment, the third hole 30c has the same shape as the second hole 20c, and is arranged with respect to the second hole 20c at the same spacing as the spacing between the second holes 20c. Although the shape and arrangement do not necessarily have to be such, it is possible to make the shape of the first hole 10c arranged between the third hole 30c and the second hole 20c similar to that of the second hole 20c. The shape of the first hole 10c can be approximated to that of the first hole 10c located between the two holes.

The third holes 30c, 32c may be provided so as to reduce the number of the first holes 10c, which have the second holes 20c, 32c on only one side. In this embodiment, all the first holes 10c are arranged between the second holes 20c and 22c or between the second holes 20c and 22c and the third holes 30c and 32c, so that the first holes The difference in shape of 10c can be reduced.

When the plates 4d and 4f are stacked, the third holes 30c arranged in the plates 4d and 4f are covered at the top and bottom with other plates, thereby forming the first dummy manifold 30. The first dummy manifold 30 is a sealed space and is not directly involved in ejecting liquid. If a hole is provided to connect the first dummy manifold 30 to the outside, air can be easily removed during lamination processing, and lamination defects are less likely to occur. Further, the first dummy manifold 30 may be connected to the first common channel 20 to flow the liquid. In this case, "dummy" means that liquid is not directly supplied to or collected from the pressurizing chamber 10.

The third hole 32c is a hole extending in the first direction like the second hole 22c, and is the end in the second direction of the second hole 22c lined up in the second direction, and the opposite direction to the second direction. It is arranged at the end in the fourth direction. In this embodiment, the third hole 32c has the same width as the second hole 22c, but the length is the same as the second hole 20c. Moreover, the third hole 32c is arranged at the same interval as the arrangement interval between the second holes 22c with respect to the second hole 22c. Although the shape and arrangement do not necessarily have to be such, it is possible to make the shape of the first hole 10c arranged between the third hole 32c and the second hole 22c similar to that of the second hole 22c. The shape of the first hole 10c can be approximated to that of the first hole 10c located between the two holes. In order to reduce the difference in etching shape, it is preferable that the length of the third hole 32c is longer than the range in which one hole 10c is arranged. It is preferable to make the length longer than the width of the hole 32c. In this embodiment, the third hole 32c is made shorter than the second hole 22c, thereby increasing the rigidity at the end of the flow path member 4 .

The third holes 32c arranged in the plates 4i and 4j are covered at the top and bottom with other plates in the stacked state, thereby forming a second dummy manifold 32. The second dummy manifold 32 is a sealed space and is not directly involved in ejecting liquid. If a hole is provided to connect the second dummy manifold 32 to the outside, air can be easily removed during lamination processing, and lamination defects are less likely to occur. Further, the second dummy manifold 32 may be connected to the second common flow path 22 to flow the liquid. In this case, "dummy" means that liquid is not directly supplied to or collected from the pressurizing chamber 10.

The holes in the plates 4e, f, i, and j are formed by placing the plates 4e, f, i, and j coated with resist except for the portions to be processed into a tank containing an etching solution, and etching them. In the tank, the etching solution is stirred so that the new etching solution easily hits the plates 4e, f, i, and j. If the holes formed in the plates 4e, f, i, and j are arranged as described above, even if the shape of the first hole 10c that forms part of the pressurizing chamber 10 varies, the variation will be noticeable to the human eye. It is possible to manufacture a liquid ejection head 2 that is difficult to manufacture.

1... Color inkjet printer 2... Liquid ejection head 2a... Head main body 4... (First) channel member 4a-l... Plate 4-1... Pressure chamber surface 4- 2...Discharge hole surface 6...Second channel member 6a...Through hole (of the second channel member) 8...Discharge hole 9A...Discharge hole row 10...Pressure chamber 10a... Pressure chamber main body 10b... Partial flow path 10c... First hole 11A... Pressure chamber row 12... First flow path 14... Second flow path 14a... Individual channel 14b... Connection channel 20... First common channel 20a... First common channel main body 20b... Opening (of the first common channel) 20c... Second hole 22 ...Second common flow path 22a...Second common flow path main body 22b...Opening (of the second common flow path) 22c...Second hole 24...First integrated flow path 24a...・First integrated flow path main body 24b... (Opening of the first integrated flow path) 26... Second integrated flow path 26a... Second integrated flow path main body 26b... (Opening of the second integrated flow path) ) Opening 28A, B... Damper 29A, B... Damper chamber 30... First dummy manifold 30c... Third hole 32... Second dummy manifold 32c... Third hole 34A... - First hole row 36... First hole group 37... Second hole group 40... Piezoelectric actuator substrate 40a... Piezoelectric ceramic layer 40b... Piezoelectric ceramic layer (diaphragm)
42...Common electrode 44...Individual electrode 44a...Individual electrode body 44b...Leader electrode 46...Connection electrode 50...Displacement element (pressure part)
70... Head mounting frame 72... Head group 80A... Paper feed roller 80B... Collection roller 82A... Guide roller 82B... Conveyance roller 88... Control unit D1... First Direction D2...Second direction D3...Third direction D4...Fourth direction P...Printing paper

Claims (9)

A channel member formed by stacking a plurality of plates, which has a plurality of discharge holes, a plurality of pressurizing chambers connected to the plurality of discharge holes, a plurality of common channels, and at least one dummy common channel; A liquid ejection head including a plurality of pressurizing parts that pressurize the plurality of pressurizing chambers,
The plurality of common channels have a plurality of first common channels and a plurality of second common channels, and the plurality of first common channels and the plurality of second common channels are the plurality of common channels. The plurality of first common channels are arranged to overlap with the plurality of second common channels in the stacking direction of the plates, and each extends along the first direction, and are arranged side by side in a second direction, which is a direction that intersects the direction,
If the region where the plurality of pressurizing chambers are arranged is a first region, and the direction opposite to the first direction is a third direction,
Each of the plurality of common channels has a length extending from an end in the first direction to an end in the third direction in the first region,
The at least one dummy common flow path extends along the first direction and has a length from an end in the first direction to an end in the third direction in the first region,
The flow path member includes the plurality of plates, and the plate includes a plurality of first holes that become a part of the pressurizing chamber, and a plurality of first common flow paths or a plurality of second common flow paths. A plurality of second holes that become part of the common flow path and at least one third hole that becomes part of the dummy common flow path are arranged,
When the plate is viewed from above,
Like the common flow path, the plurality of second holes each extend along the first direction and are arranged in line in the second direction,
If the region where the plurality of first holes are arranged is a second region,
Each of the plurality of second holes has a length extending from an end in the first direction to an end in the third direction in the second region,
The at least one third hole extends along the first direction similarly to the dummy common flow path, and has a length extending from the end in the first direction to the end in the third direction in the second region. It has a
The plurality of first holes constitute a plurality of first hole rows in which the plurality of first holes are arranged side by side in the first direction,
Among the plurality of first holes, at least one of the first holes is arranged so as to overlap vertically and is not arranged between the second holes arranged in line in the second direction. The liquid ejection head is disposed between the second hole and the third hole that are arranged in the second direction . Among the plurality of first holes, at least a portion of the first holes that are not arranged between the second holes that are arranged to overlap are between the second hole and the third hole. The liquid ejection head according to claim 1, wherein the liquid ejection head is arranged. All of the plurality of first holes are arranged either between the second holes, between the second hole and the third hole, or between the third holes. 3. The liquid ejection head according to 1 or 2. When the plate is viewed from above,
The plurality of first hole rows are arranged in line in the second direction,
When the distance from the first hole to the closest one of the second hole and the third hole is the distance L,
Among the plurality of first holes, there are ones with different distances L,
When divided into a first group consisting of the first holes where the distance L is short and a second group where the distance L is longer than the first group,
Liquid ejection according to any one of claims 1 to 3, wherein the first holes belonging to the first group and the first holes belonging to the second group are arranged alternately with respect to the first direction. head. 5. The liquid ejection head according to claim 4, wherein the distances L of the first holes belonging to the first group are all the same, and the distances L of the first holes belonging to the second group are all the same. The planar shape of the first hole is circular, the radius of the first hole on at least one of the upper surface and the lower surface of the plate in which the first hole is formed is R1, and The liquid ejection head according to claim 1, wherein R1≧2T/3, where T is the thickness of the plate. The planar shape of the first hole is circular, and when the radius of the first hole at the position with the smallest diameter in the depth direction of the first hole is R2, R2≧0.9R1. 7. The liquid ejection head according to claim 6. A recording apparatus comprising: the liquid ejection head according to any one of claims 1 to 7; a conveyance section that conveys a recording medium to the liquid ejection head; and a control section that controls the liquid ejection head. Includes a flow path member formed by laminating a plurality of plates, which has a plurality of discharge holes, a plurality of pressurizing chambers connected to the plurality of discharge holes, a plurality of common flow paths, and at least one dummy common flow path. A method for manufacturing a liquid ejection head, the method comprising:
The plurality of common channels have a plurality of first common channels and a plurality of second common channels, and the plurality of first common channels and the plurality of second common channels are the plurality of common channels. The plurality of first common channels are arranged to overlap with the plurality of second common channels in the stacking direction of the plates, and each extends along the first direction, and are arranged side by side in a second direction, which is a direction that intersects the direction,
If the region where the plurality of pressurizing chambers are arranged is a first region, and the direction opposite to the first direction is a third direction,
Each of the plurality of common channels has a length extending from an end in the first direction to an end in the third direction in the first region,
The at least one dummy common flow path extends along the first direction and has a length from an end in the first direction to an end in the third direction in the first region,
The flow path member includes the plurality of metal plates processed by an etching process,
In the etching step, a plurality of first holes forming a part of the plurality of pressurizing chambers, a part of the plurality of first common channels or a part of the plurality of second common channels are formed in the plate. The arrangement of the plurality of second holes that become a part of the dummy common flow path and the at least one third hole that becomes a part of the dummy common flow path,
When the plate is viewed from above,
Like the common flow path, the plurality of second holes each extend along the first direction and are arranged in line in the second direction,
If the region where the plurality of first holes are arranged is a second region,
Each of the plurality of second holes has a length extending from an end in the first direction to an end in the third direction in the second region,
The at least one third hole extends along the first direction similarly to the dummy common flow path, and has a length extending from the end in the first direction to the end in the third direction in the second region. It has a
The plurality of first holes constitute a plurality of first hole rows in which the plurality of first holes are arranged side by side in the first direction,
Among the plurality of first holes, the plurality of first holes are arranged to overlap vertically in the stacking direction of the plurality of plates , and are arranged between the second holes arranged in line in the second direction. At least a portion of the first holes that are not filled are located between the second holes and the third holes that are arranged in parallel in the second direction .
A method of manufacturing a liquid ejection head, which is an arrangement.

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