JP3864676B2 - Inkjet head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet head, and more particularly to an ink jet head used in an ink jet type printing apparatus that prints on a recording medium by ejecting ink.
[0002]
[Prior art]
Today, instead of the conventional impact printing devices, the non-impact printing devices that are expanding the market are the simplest in principle and easy to multi-tone and color. As an example, an ink jet printing apparatus can be given.
[0003]
As disclosed in Japanese Patent Application Laid-Open No. 10-272770, the applicant also forms a plurality of channels for containing ink in an aligned state as an ink jet head used in an ink jet type printing apparatus. An actuator that drives the ink to be ejected as droplets from a nozzle, and is joined to the actuator on the inlet end side of the channel, and is arranged to align the plurality of channels to supply ink to each channel And a manifold having a supply path extending in the direction and having a common opening to each inlet end of the channel.
[0004]
[Problems to be solved by the invention]
In general, in an ink jet printing apparatus, fine bubbles may be dissolved or dust may be mixed in ink supplied to an ink jet head. There is a possibility that the bubbles grow and block the ink flow path, or the ink ejection failure is caused by dust and the print quality is deteriorated.
[0005]
Therefore, it is known to perform a purge operation in order to recover and maintain the ink ejection function of the inkjet head. In the purge operation, a large negative pressure is generated by a suction pump connected to the suction cap while the suction cap is in contact with the nozzle surface of the inkjet head, and a predetermined amount of ink inside the inkjet head together with bubbles and dust is passed through the suction cap. By sucking, the ink flow path is filled with ink, and bubbles and dust in the ink flow path are discharged to the suction cap side.
[0006]
However, in the ink jet head described in the above publication, since the inlet end of the channel opens to the flat surface of the head forming member, the purge operation is performed when relatively large spherical bubbles are included in the ink. However, there is a problem that it is difficult to discharge the large bubbles and ink ejection defects are likely to occur.
[0007]
That is, FIG. 17 shows the state. 17 (a ′) and 17 (b ′) are front views of the inlet end side of the channel groove 31 from the inside of the ink supply path 41 in the manifold. 17 (a) and 17 (b) are enlarged cross-sectional views of the inlet end side of the channel groove 31, and are cross-sectional views taken along the line XX of FIGS. 17 (a ′) and 17 (b ′).
[0008]
Even if a relatively large bubble EB adheres to the inlet end of the channel groove 31 due to the ink flow generated by the purge operation or the flushing operation, the bubble EB blocks only a part of the inlet end, and the inlet end is blocked. The part 31a which is not performed arises. On the other hand, since the inlet end of the channel groove 31 is open on a plane, the ink flowing from the portion 31 a is deformed so as to draw the bubble EB into the channel groove 31 only by freely flowing in a wide space around the bubble EB. I don't want to let you. That is, the bubble EB is going to be spherical due to the surface tension so as to minimize its surface area. Even when the bubble EB enters the channel groove 31 slightly as shown in FIG. 17B, the surface area changes rapidly, so that the force to restore the spherical shape is large, and it is not easily drawn into the channel groove 31. As a result, even if the purge operation and the flushing operation are repeated, there is a situation in which the bubbles EB cannot be discharged, and ink quality is insufficiently supplied to the channel groove 31 or ejection becomes impossible. It was.
[0009]
The present invention has been made to solve the above problems, and an object of the present invention is to provide an ink jet head that can easily discharge bubbles to prevent defective ejection of ink and perform normal printing. There is.
[0010]
[Means for Solving the Problems]
In order to achieve this object, the invention according to claim 1 is characterized in that a plurality of channels are formed in an aligned state, and the nozzle holes provided in the outlet end side of the corresponding channels are respectively accommodated in the channels. Ink comprising a substrate ejected as droplets, and a recess that extends in the alignment direction of the plurality of channels and opens at the inlet end side of each channel and at a side perpendicular to and parallel to the alignment direction. A manifold formed with a supply path; and a plate member fixed to the substrate and the manifold and covering an opening of the ink supply path on a side orthogonal to the inlet end of the channel; The opening at the inlet side end of the channel is connected to the inlet ends of the plurality of channels, and the ink supplied from the ink supply source passes through the ink supply path before the ink. An ink jet head for supplying to an inlet end of each channel, wherein a plurality of the manifolds are provided along an opening end on the inlet end side of the channel of the ink supply path, and an ink supply of the manifold is provided therebetween. A channel for introducing the ink in the channel into each channel. For each channel An opening forming member to be formed is formed by projecting from the bottom wall facing the plate member of the ink supply path toward the plate member side, and the cross-sectional shape of the flow path between the opening forming members is The shape gradually narrows from the opening end on the ink supply path side toward the channel so that the bubbles contained in the ink in the ink supply path gradually approach the shape of at least two opposing sides of the inlet end of the channel. The main point is to deform the bubbles.
[0011]
Therefore, according to the present invention, the shape of the bubbles contained in the ink in the ink supply path of the manifold is gradually deformed to be close to the shape of at least the two opposite sides of the inlet end of the channel. Since the air bubbles are smoothly introduced, the bubbles can be discharged by the purge operation and the flushing operation, and it is possible to perform normal printing while preventing ink ejection failure. Note that the shape of the bubble does not necessarily have to be close to the shape of the inlet end, and it is only necessary to deform the bubble so that at least two opposing sides of the inlet end are close to the outer shape of the bubble.
[0012]
By the way, as in the invention according to claim 2, in the ink jet head according to claim 1, the inlet end of the channel is formed such that one of two orthogonal widths is larger than the other, and the opening is formed. The member has a difference in which the two orthogonal widths are smaller than the difference between the two widths of the inlet end of the channel from the opening end on the ink supply path side toward the inlet end of the channel. You may make it have the cross-sectional shape narrowed to.
[0013]
Next, according to a third aspect of the present invention, in the ink jet head according to the first or second aspect, the opening end on the ink supply side of the flow path between the opening forming members is orthogonal 2. Of the two widths, one width orthogonal to the alignment direction of the plurality of channels is configured to be larger than the other width parallel to the alignment direction of the plurality of channels, and the latter width gradually increases toward the channels. The gist is narrowing.
[0014]
[0015]
[0016]
[0017]
[0018]
[0019]
[0020]
[0021]
[0022]
[0023]
[0024]
[0025]
[0026]
Next, according to a fourth aspect of the present invention, in the ink jet head according to the first or second aspect, the plurality of channels are formed in an aligned state in each row while forming a plurality of rows, and the ink supply path The gist thereof is that each of the channels is formed along each row of the plurality of channels.
[0027]
As in the present invention, a plurality of channels are formed in a plurality of rows while being aligned in each row, and the ink supply path is formed along each row of the plurality of channels, so that each row For example, multi-color printing using different inks can be realized. In this case, if the columns are close to each other, the volume and cross-sectional area of the ink supply path cannot be increased so much that a sufficient volume for the bubble growth cannot be secured, and the ink supply path cannot be secured. Air bubbles and dust cannot stay for a long time, and the air bubbles are drawn into the channel and easily stay in the channel. Further, an increase in pressure loss due to an increase in flow rate tends to cause ink ejection failure. Therefore, as in the invention described in claim 1 or 2, it is important to be able to effectively remove bubbles in the ink supply path.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. In the embodiments of the invention described below, “ink supply source” described in the claims (claims 1 to 4) or means for solving the problem corresponds to the ink cartridge 509.
[0029]
FIG. 1 is a perspective view illustrating a schematic configuration of a color inkjet printer 1 including an inkjet head 600 according to the present embodiment.
The guide rod 501 and the guide member 502 are fixed to the printer frame 503.
[0030]
The carriage 504 is slidably supported by the guide rod 501 and the guide member 502, fixed to the belt 505, and driven by the carriage motor 506 to reciprocate. The belt 505 is wound around pulleys 507 arranged in the vicinity of both ends of the long guide rod 501 and the guide member 502. One pulley 507 is connected to the drive shaft of the carriage motor 506.
[0031]
A head unit 508 in which two sets of inkjet heads 600 are arranged side by side is attached to the carriage 504. Each inkjet head 600 is connected to a drive control circuit (not shown) described later. An ink cartridge 509 that supplies ink to nozzle holes (not shown), which will be described later, is detachably mounted on the rear portion of each inkjet head 600.
[0032]
A transport mechanism LF that transports the printing paper P as a recording medium is disposed at a position facing the inkjet head 600. The transport mechanism LF transports the printing paper P by the rotation of the platen roller 511 that is rotated by driving the transport motor 510. A roller shaft 512 of the platen roller 511 is rotatably supported by the printer frame 503.
[0033]
As described above, in the color inkjet printer 1, the reciprocating movement of the carriage 504 and the conveyance of the printing paper P cooperate to eject ink droplets from the inkjet head 600 to a desired area on the printing paper P. Print as desired.
Since the color ink jet printer 1 performs color printing with four color inks (cyan, magenta, yellow, and black), the ink cartridge 509 stores four color inks. As described later, since the inkjet head 600 is configured to eject two color inks independently, two sets of inkjet heads 600 are provided for four color inks.
[0034]
Further, the color inkjet printer 1 is provided with a maintenance / recovery mechanism RM for maintaining / recovering the ink ejection operation of the inkjet head 600. The maintenance / recovery mechanism RM includes a purge device 513 and a flushing ink absorbing member 516.
[0035]
The purge device 513 is disposed on the side of the platen roller 511 so as to face the inkjet head 600 in a reset state. The purge device 513 generates a large negative pressure by the suction pump 515 connected to the suction cap 514 in a state where the suction cap 514 is in contact with the nozzle surface of the inkjet head 600, and the inside of the inkjet head 600 is passed through the suction cap 514. A purging operation is performed in which a predetermined amount of ink is sucked together with bubbles and dust. By this purging operation, it becomes possible to eliminate the ejection failure caused by bubbles and dust remaining in the ink jet head 600, and it is possible to achieve a good recovery of the ejection state.
[0036]
The flushing ink absorbing member 516 is made of a porous material plate having excellent ink absorbability, and is disposed on the side of the platen roller 511 opposite to the purge device 513 so as to face the inkjet head 600 in a reset state. Yes. Before the ink is ejected from the inkjet head 600 to the printing paper P, a flushing operation is performed in which the ink is ejected from the inkjet head 600 to the flushing ink absorbing member 516. This flushing operation makes it possible to discharge bubbles and dust remaining inside the inkjet head 600 together with the ink to the flushing ink absorbing member 516. Therefore, coupled with the purge operation, the ejection failure is eliminated and a good ejection state is achieved. Recovery can be achieved.
[0037]
FIG. 2 is a perspective view showing the inkjet head 600.
The ink jet head 600 includes substrates 11 and 12 having piezoelectric elements, manifold members 13 and 14, a plate member 15, and a nozzle plate 16.
[0038]
Flat plate rectangular substrates 11 and 12 are attached and fixed to both sides of the front portion of the flat plate member 15, and flat plate manifold members 13 and 14 are attached and fixed to both rear portions of the plate member 15. Yes. That is, the plate member 15 is extended to the rear end side with respect to the substrates 11 and 12, and is formed at each corner portion formed by both side surfaces of the extension portion of the plate member 15 and the rear end surfaces of the substrates 11 and 12. The front ends of the manifold members 13 and 14 are connected. Each substrate 11, 12, plate member 15, and nozzle plate 16 constitute an actuator 24.
[0039]
The front end surfaces of the substrates 11 and 12 and the plate member 15 are flush with each other, and a flat-plate nozzle plate 16 is stuck and fixed so as to close the front end surfaces.
At connection portions (rear ends of the substrates 11 and 12, outer peripheral portions of the manifold members 13 and 14, and rear portions of the plate member 15) of the substrates 11 and 12, the manifold members 13 and 14 and the plate member 15. Is applied with a sealing material 17 made of an appropriate material (for example, silicon rubber), and the manifold members 13 and 14 are fixed to the substrates 11 and 12 and the plate member 15 by the sealing material 17. Ink leakage from the members 13 and 14 is prevented.
[0040]
A plurality of lead-out grooves 21 connected to and communicated with dummy grooves (not shown) to be described later are formed at the front end portions of the substrates 11 and 12. A circular ink supply hole 22 is formed in the lower part of each manifold member 13, 14.
FIG. 3 is a perspective view showing a state where the sealing material 17 is removed from the inkjet head 600.
[0041]
A plurality of introduction grooves 23 connected to and communicated with dummy grooves, which will be described later, are formed at the front end portions of the manifold members 13 and 14. As shown in FIG. 2, each introduction groove 23 is sealed with a sealing material 17.
FIG. 4 is a partial vertical cross-sectional view of the inkjet head 600, and is a cross-sectional view taken along line YY in FIG.
[0042]
FIG. 5 is a perspective view showing a state in which a part of each of the substrates 11 and 12 is viewed from the front end side.
6 is a cross-sectional view of the inkjet head 600, and is a cross-sectional view taken along line XX in FIG.
[0043]
FIG. 7 is an exploded perspective view showing a state where the manifold members 13 and 14 are removed from the inkjet head 600.
FIG. 8 is a perspective view showing a state in which a part of the manifold member 14 is viewed from the back surface (surface connected to the plate member 15) side.
[0044]
FIG. 9 is a plan view showing the back surface side of a part of the manifold member 14 and the substrate 12.
FIG. 10 is a plan view showing the back side of the manifold member 13.
FIG. 11 is a plan view showing the back side of the manifold member 14.
[0045]
4 to 9 are schematic diagrams for explaining the configuration of the ink jet head 600, and there are places where the dimensions of each member of the ink jet head 600 do not match between the drawings. This is to make the configuration easy to understand. 10 and 11 show the actual manifold members 13 and 14, and therefore there are places where the dimensional shape of each member does not match that of FIGS.
[0046]
As shown in FIGS. 4 and 5, the back surfaces (surfaces connected to the plate member 15) of the substrates 11 and 12 are linearly grooved in parallel with the cross-sectional direction of the inkjet head 600 shown in FIG. 2. A plurality of channel grooves 31 and dummy grooves 32 are formed in an alternately aligned state. The open top of each channel groove 31 and each dummy groove 32 is covered with a plate member 15, and the ejection channel of the actuator 24 is formed by the channel groove 31 covered with the plate member 15. A dummy channel of the actuator 24 is formed by the dummy groove 32 covered by the above.
[0047]
The side walls of each channel groove 31 and each dummy groove 32 are formed of a shear mode type upper wall 33 and lower wall 34 made of an appropriate piezoelectric material (for example, piezoelectric ceramics) polarized in the opposite direction. . That is, the upper wall 33 is connected to the plate member 15 and is polarized in the direction of the plate member 15 (arrow A direction). The lower wall 34 is connected to the bottoms of the grooves 31 and 32 and is polarized in the direction opposite to the polarization direction of the upper wall 33 (in the direction of arrow B).
[0048]
Electrodes 35 are formed on the inner wall surface including the bottom of each channel groove 31, and electrodes 36 are formed on both side walls except for the bottom of each dummy groove 32. The electrodes 35 provided in the channel grooves 31 are grounded, and the electrodes 36 provided in the dummy grooves 32 are connected to the drive control circuit 37, respectively. The drive control circuit 37 generates a drive signal and applies it to each electrode 36.
[0049]
As shown in FIGS. 4 and 6, nozzle holes 16 a are formed at the outlet ends of the channel grooves 31 in the nozzle plate 16.
As shown in FIG. 6, when the substrates 11 and 12 are connected to both surfaces of the plate member 15, the plurality of channel grooves 31 formed in the substrates 11 and 12 are aligned in two rows. Two independent channel groups are configured by the channel grooves 31 arranged in each row. Further, each channel groove 31 and each dummy groove 32 are formed to fill the width direction of each substrate 11, 12, and both end portions of each channel groove 31 and each dummy groove 32 are opened from both end surface sides of each substrate 11, 12. ing. The front end portion of each dummy groove 32 is connected to and communicated with each lead-out groove 21 of each substrate 11 and 12, and the rear end portion of each dummy groove 32 is connected and communicated to each introduction groove 23 of each manifold member 13 and 14. Each introduction groove 23 is filled with a sealing material 17. The sealing material 17 in the introduction groove 23 is for preventing ink supplied from an ink supply path 41 (described later) to the channel groove 31 from leaking into the dummy groove 32. In FIG. 6, the sealing material 17 is also filled in the dummy groove 32. This is because the liquid sealing material placed outside the manifold members 13 and 14 is sucked from the lead-out groove 21 side by vacuum suction. When it fills in the introduction groove 23, it flows into the dummy groove 32, and is not necessary originally.
[0050]
As shown in FIGS. 6 to 11, each manifold member 13, 14 is formed with an ink supply path 41 composed of a recess formed at a certain depth in the plate thickness direction of each manifold member 13, 14. Yes. An ink supply hole 22 is formed in the start end portion 41 b of the ink supply path 41 of each manifold member 13, 14, and an opening forming member 42, a filter member 43, and a rib-like protrusion 44 are formed in each ink supply path 41. ing. The ink supply path 41 of each manifold member 13, 14 is formed in a symmetric structure with respect to the plate member 15, including the members 42 to 44 therein.
[0051]
As shown in FIGS. 7, 10, and 11, the planar shape of the ink supply path 41 is from the start end 41 b (lower part of the ink supply path 41) where the ink supply hole 22 is formed to the final end 41 a (ink supply path). The width is gradually narrowed toward the upper portion of 41 and extends in the alignment direction of the channel grooves 31 of the substrates 11 and 12. One side portion of the ink supply path 41 opens in common to the inlet ends of the channel grooves 31 of the substrates 11 and 12, and a plurality of opening forming members 42 are provided in the opening portions. Yes.
[0052]
As shown in FIGS. 7 to 11, each opening forming member 42 has a substantially semi-spindle cross section, and an opening 45 is formed by a gap between each opening forming member 42. Each opening forming member 42 is connected to the inlet end side of each channel groove 31 in each substrate 11, 12. Each opening forming member 42 is disposed to face each dummy groove 32, and each opening 45. Are arranged opposite to each channel groove 31 and connected to each other. In addition, an introduction groove 23 is formed on the end face of each opening forming member 42 on the side of the substrate 11, 12, and one end of each introduction groove 23 opens to the outside of each manifold member 13, 14. The other end is connected to and communicated with the rear end portion of each dummy groove 32.
[0053]
As shown in FIGS. 7 to 11, in each manifold member 13, 14, each opening 45 (inlet end of each channel groove 31) between each opening forming member 42 and ink supply facing each opening 45. Between the wall surface 41c of the path 41, filter members 43a and 43b having a long cylindrical shape are formed. The filter members 43 a and 43 b are arranged in two rows parallel to the alignment direction of the openings 45, and the filter members 43 a in the row closer to the opening formation members 42 correspond to the opening formation members 42. The filter members 43b in the row on the side close to the wall surface 41c of the ink supply path 41 are arranged corresponding to the openings 45. That is, each filter member 43a is arranged corresponding to a gap between each filter member 43b. And each filter member 43a is arrange | positioned at predetermined intervals t from the front-end | tip part of each opening part formation member 42. FIG. Further, the semicircular ends of the filter members 43a and 43b are arranged close to each other, and the gap between the ends is formed narrow so as to prevent the flow of minute bubbles and dust. The filter members 43 a and 43 b are formed perpendicular to the bottom surface of the ink supply path 41 and the plate member 15.
[0054]
Each of the filter members 43 a and 43 b has a portion corresponding to two openings 45 a and 45 b (inlet ends of the two channel grooves 31) located at the final end 41 a of the ink supply path 41, and the ink supply path 41. It is not provided in a portion corresponding to the opening 45c (inlet end of the channel groove 31) located at the start end 41b. That is, the filter members 43a and 43b are not disposed in the vicinity of the inlet ends at both ends of the channel grooves 31 in the alignment direction. The opening forming members 42a and 42b adjacent to the openings 45b and 45c are extended and connected to the filter member 43a.
[0055]
As shown in FIGS. 7, 10, and 11, in each manifold member 13, 14, each opening 45 (inlet end of each channel groove 31) between each opening forming member 42 is opposed to each opening 45. A thin plate shape for guiding ink from the ink supply hole 22 toward the alignment direction end of each opening 45 (alignment direction end of each channel groove 31) between the wall surface of the ink supply path 41 to be performed. Each rib-shaped protrusion 44a-44h which it comprises has extended. That is, the rib-like protrusions 44 a to 44 h are arranged between the ink supply holes 22 and the openings 45 and are arranged in two rows from the ink supply holes 22 toward the alignment direction ends of the openings 45. The rib-like projections 44b, 44d, 44f in one row are arranged corresponding to the gaps between the rib-like projections 44a, 44c, 44e, 44g, 44h in the other row. The rib-shaped protrusions 44 a to 44 h are formed perpendicular to the bottom surface of the ink supply path 41 and the plate member 15.
[0056]
The top portions of the opening forming members 42, the filter members 43, and the rib-like projections 44 are connected and fixed to the plate member 15 in a liquid-tight manner.
Each manifold member 13, 14 is integrally formed with an ink supply path 41, an opening forming member 42, a filter member 43, and a rib-like protrusion 44 by injection molding of a synthetic resin material.
[0057]
By the way, the ink jet head 600 is attached to the carriage 504 in a horizontally horizontal state as shown in FIG. 1, and the ink supply holes 22 of the manifold members 13 and 14 are arranged on the lower side in this state. The ink jet head 600 may be disposed at an angle of about 45 ° with respect to the main body of the color ink jet printer 1 with the nozzle plate 16 facing downward and the manifold members 13 and 14 facing upward. The ink jet head 600 may be arranged vertically downward with respect to the main body of the color ink jet printer 1 with the nozzle plate 16 facing downward.
[0058]
Next, the operation and effect of the present embodiment configured as described above will be described.
Each color ink stored in the ink cartridge 509 shown in FIG. 1 is independently supplied to the ink supply holes 22 of the manifold members 13 and 14, and the ink supply holes 22 of the manifold members 13 and 14 → the manifolds. The ink is supplied into the channel grooves 31 through the ink supply paths 41 of the members 13 and 14, the openings 45 of the manifold members 13 and 14, and the channel grooves 31 of the substrates 11 and 12.
[0059]
Here, the channel grooves 31 formed in the substrates 11 and 12 are completely separated by the extension of the plate member 15. Accordingly, when connecting the manifold members 13 and 14 to the rear end surfaces of the substrates 11 and 12, respectively, the channel grooves 31 between the substrates 11 and 12 which are ink flow paths of different colors, even in rough operations. In addition, the ink supply paths 41 between the manifold members 13 and 14 are not connected to each other, and different color inks are not mixed. For this reason, it is possible to prevent ink from mixing between two independent channel groups formed by the channel grooves 31 formed in the substrates 11 and 12, and to perform reliable color separation. .
[0060]
Then, as shown in FIG. 4, in a state where ink is supplied into each channel groove 31, an electrode 36 on the channel groove 31a side in two dummy grooves 32 sandwiching an arbitrary channel groove 31a is applied from the drive control circuit 37. When a drive signal of a predetermined voltage E (V) is applied, electric fields in the directions of arrows C and D are generated on the side walls (upper wall 33 and lower wall 34) of the channel groove 31a sandwiched between the dummy grooves 32, respectively. Then, the side wall portion of the channel groove 31a is deformed in a piezoelectric thickness direction so as to increase the volume of the channel groove 31a. Then, the pressure in the channel groove 31a including the vicinity of the nozzle hole 16a decreases.
[0061]
Here, when the application of the drive signal from the drive control circuit 37 is maintained for the one-way propagation time T of the pressure wave in the channel groove 31a, ink is supplied from the ink cartridge 509 to the channel groove 31a through the path during that period. The Note that the one-way propagation time T is a time during which the pressure wave of the ink in the channel groove 31 propagates one-way in the longitudinal direction of the channel groove 31, and the length L of the channel groove 31 shown in FIG. Is calculated by the equation T = L / S.
[0062]
According to the propagation theory of the pressure wave, when the one-way propagation time T elapses from the application of the drive signal, the pressure in the channel groove 31a is reversed and turned to a positive pressure. Return to V). Then, the side wall portion of the channel groove 31a returns to the state before deformation, and pressure is applied to the ink. As a result, the positive pressure and the pressure generated when the side wall portion returns to the state before deformation are added together, and a relatively high pressure is generated in the vicinity of the nozzle hole 16a in the channel groove 31a. Ink droplets are ejected from 16a.
[0063]
Here, if a material having flexibility (for example, silicon rubber) is used as the sealing material 17 filled in the dummy groove 32, each dummy is provided even when the sealing material 17 is filled in each dummy groove 32. Each dummy groove 32 can be freely deformed without hindering the deformation of the groove 32, so that the volume change of the channel groove 31a during ink ejection is not hindered.
[0064]
12 (a ′) to 12 (c ′) are front views showing a state in which the opening forming member 42, the opening 45, and the inlet end side of the channel groove 31 are viewed from the inside of the ink supply path 41. FIG.
12 (a) to 12 (c) are enlarged cross-sectional views of the main parts showing the inlet end side of the opening forming member 42, the opening 45, and the channel groove 31, and FIG. 12 (a ′) to FIG. It is XX sectional drawing in c ').
[0065]
Each opening forming member 42 is provided on the inlet end side of each channel groove 31 in the ink supply path 41, and each opening 45 is formed by a gap between each opening forming member 42. The cross-sectional area of the path gradually decreases from the ink supply path 41 toward the inlet end side of each channel groove 31.
[0066]
The bubbles EB contained in the ink in the ink supply path 41 are originally spherical. As the relatively large bubble EB passes through the flow path in the opening 45, the shape of the bubble EB is gradually deformed from a spherical shape to a flat shape along the shape of the flow path. Since the shape is close to the shape of the inlet end side of the channel groove 31, the bubbles EB are smoothly introduced into the channel groove 31.
[0067]
Here, the cross-sectional shape of each channel groove 31 is an elongated rectangular shape with a large aspect ratio (high aspect ratio), and the shape of each channel groove 31 on the inlet end side is the same as the cross-sectional shape. . The cross-sectional shape of the flow path in each opening 45 is such that the vertical width n shown in FIG. 12 (a ′) is constant and equal to each channel groove 31, and the horizontal width m is each opening forming member 42. It gradually spreads toward the tip of the channel (that is, gradually narrows toward the inlet end of each channel groove 31). In other words, the shape of each opening 45 at the tip of each opening forming member 42 (the shape of the opening end on the ink supply path 41 side in each opening 45) is one of two orthogonal widths n and m. The width n is larger than the other width m, and it has a long and narrow rectangular shape with a large aspect ratio (high aspect ratio).
[0068]
Since the original bubble EB has a spherical shape, if the opening end on the ink supply path 41 side of each opening 45 has a shape close to a square, the bubble EB blocks a wide portion of the opening end. Therefore, the bubble EB is drawn to a state where a part thereof is inserted into the tapered opening 45 by the purge operation and the flushing operation. In this state, since the change in the surface area of the bubbles EB is smaller than that in the conventional case of FIG. 17, the restoring force due to the surface tension is also small. Moreover, since the bubble EB covers a wide portion of the opening 45, it is easily sucked to the channel groove 31 side by the purge operation and the flushing operation. On the other hand, even if there is a portion 45d that is not blocked by the bubble EB, the ink flowing into the portion flows along the inside of the tapered opening 45 only on the side surface of the bubble EB in the direction of the channel groove 31 and gradually. It becomes faster and works strongly in the direction of drawing the bubbles EB. As a result, the bubbles EB are gradually deformed according to the cross-sectional shape of the opening 45, drawn into the channel groove 31, and discharged to the outside through the channel groove 31.
[0069]
Therefore, even if a relatively large spherical bubble EB is included in the ink in the ink supply path 41, the bubble EB can be reliably removed by the purge operation and the flushing operation. Therefore, it is possible to perform normal printing by preventing the ejection failure of ink.
[0070]
In the present embodiment, since the manifold members 13 and 14 are integrally formed with the opening forming members 42 by injection molding of synthetic resin, the opening forming members 42 having a fine and precise shape can be easily created. can do. The opening end of the opening 45 on the ink supply path 41 side is desirably a square or a shape close to a circle.
[0071]
Next, an inkjet head 700 as a reference example of the present invention will be described. In the following description, the same reference numerals as those used in FIGS. 1 to 12 are attached to the components common to the inkjet head 600, and detailed description of the configuration is omitted.
[0072]
As shown in the cross-sectional view of FIG. 13, the inkjet head 700 includes the substrates 11 and 12, the plate member 15, and the nozzle plate 16, similarly to the inkjet head 600. In the inkjet head 700, the front end portions of the manifold members 113 and 114 described below are connected to the respective corner portions formed by both side surfaces of the extension portion behind the plate member 15 and the rear end surfaces of the substrates 11 and 12. ing.
[0073]
14A is a perspective view showing a state in which the manifold member 114 is viewed from the back surface (surface connected to the plate member 15), and FIG. 15 shows the connection state between the manifold member 114 and the substrate 12 on the back surface side. FIG. FIG. 14B is a cross-sectional view taken along line XX of FIG. Hereinafter, the configuration of the manifold member 114 will be described with reference to FIGS. 14 and 15, but the manifold member 113 is formed in a structure symmetrical to the manifold member 114 with respect to the plate member 15.
[0074]
As shown in FIGS. 14A and 15, the manifold member 114 is formed with an ink supply path 141 formed of a recess formed in the thickness direction. The ink supply path 141 is also extended in the alignment direction of the channel grooves 31 in the same manner as the ink supply path 41 described above, and has an adhesive surface 114a that protrudes flat except for the front end portion facing the channel grooves 31. Is formed. For this reason, if the manifold member 114 is disposed as shown in FIG. 13 and the bonding surface 114 a is bonded to the plate member 15, ink can be stored in the ink supply path 141 and supplied to the channel groove 31. It becomes. The vertical width of the opening at the front end of the ink supply path 141 is the same as the vertical width n of the channel groove 31 (FIG. 12).
[0075]
An ink supply port 141 a for supplying ink into the ink supply channel 141 is provided at one end of the ink supply channel 141, and the ink supply port 141 a is provided so as to protrude to the side of the manifold member 114. It communicates with the inside of the connection port 151. Ink is supplied to the connection port 151 from an ink cartridge 509 as an ink supply source via a tube (not shown).
[0076]
Further, a tapered surface 114 b is formed on the inner surface of the manifold member 114 constituting the ink supply path 141 on the side close to the channel groove 31. As shown in FIG. 14B, the tapered surface 114b has an inclination angle of about 35 ° with respect to the bonding surface 114a. Further, at both ends of the manifold member 114, engaging portions 153 that engage with the side surfaces of the substrate 12 (both end surfaces in the inlet end arrangement direction of the channel grooves 31) are formed, and the engaging portions 153 and the connection ports 151 described above are formed. The manifold member 114 and the resin are integrally formed.
[0077]
Here, the engaging portions 153 are provided at two positions along the length direction of the channel groove 31 at any end of the manifold member 114, and abut on the both side surfaces of the substrate 12 at two positions. In addition, a slight error may occur in the position where the engaging portion 153 is formed. However, the manifold member 114 absorbs this error, so that the opening at the front end of the ink supply path 141 is arranged at the inlet end of the channel groove 31. It is formed wider than the width (see FIG. 15). In addition, the distance between the engagement portions 153 at both ends also has a slight margin from the distance between both side surfaces of the substrate 12 accordingly.
[0078]
The manifold member 114 configured as described above makes the engaging portion 153 contact the side surface of the substrate 12 with any one of the engaging portions 153 (for example, the connection port 151 side) as a reference, and the front end portion is the substrate. 12 are brought into contact with the inlet end side of the channel groove 31 and the back surface is brought into contact with the plate member 15 to be bonded (in FIG. 15, the portion bonded to the plate member 15 is hatched).
[0079]
Next, the operation and effect of this reference example configured as described above will be described.
When ink is supplied from the tube connected to the connection port 151 and sent to the channel groove 31, when the ink contains bubbles, the bubbles are transferred to the plate member 15 and the tapered surface 114 b by sending ink as described above. And the bubbles are gradually deformed so that the vertical width of the bubbles approaches the vertical width n of the inlet end of the channel groove 31. For this reason, the bubbles are smoothly introduced into the channel, and the bubbles can be discharged by the purge operation and the flushing operation, and it is possible to perform normal printing while preventing ink ejection failure.
[0080]
For example, when a large spherical bubble EB is included in the ink as shown in FIG. 16A, when it moves between the plate member 15 and the tapered surface 114b as in FIG. The ink is gradually crushed in the vertical direction, and the ink flow toward the inlet end of the channel groove 31 gradually increases along the tapered surface 114b. Therefore, the flow increases in the vertical direction as shown in FIG. Is finally brought close to the vertical width n of the inlet end. For this reason, the bubbles EB are smoothly introduced into the channel groove 31.
[0081]
Note that the angle formed by the tapered surface 114b and the side surface of the plate member 15 is not sufficiently exerted even if the angle is too large or too small. However, in the present reference example, the angle is set to 35 °. As a result, the bubbles can be well deformed and discharged. Further, in this reference example, since the bubbles can be discharged by one taper surface 114b, the configuration can be simplified compared to the above-described embodiment in which the opening forming member 42 is provided for each channel groove 31. . Further, since the positional relationship between the tapered surface 114b and each channel groove 31 may be somewhat rough, the manufacturing is facilitated and the manufacturing cost can be reduced well.
[0082]
In addition, in this reference example, the opening at the front end of the ink supply path 141 is formed wider than the arrangement width of the inlet ends of the channel grooves 31 so that the position of the manifold member 114 is slightly deviated and there is no problem. Since the positioning by the joint portion 153 is enabled, the manufacturing operation is further facilitated. Furthermore, in the present reference example, since the tapered surface 114b, the connection port 151, and the engaging portion 153 are all formed integrally with the manifold member 114, the manufacturing is further facilitated. Therefore, in this reference example, the manufacturing cost can be reduced extremely well.
[0083]
In addition, this invention is not limited to the said embodiment, You may change as follows, and even in that case, the effect | action and effect equivalent to or more than the said embodiment can be acquired.
(1) The above embodiment is embodied in the ink jet head 600 provided with the piezoelectric elements on the substrates 11 and 12, but the ink jet heads of other systems (for example, a thermal jet system using a heating element). You may apply to.
[0084]
(2) In the above embodiment, the channel grooves 31 are formed on the two substrates 11 and 12 respectively, and the channel grooves 31 are embodied in the inkjet head 600 in two rows. Either one may be omitted and the channel grooves 31 may be formed in only one row, or the channel grooves may be formed in three or more rows using three or more substrates.
[0085]
Here, as in the above embodiment, 31 rows of channel grooves are formed in each of the substrates 11 and 12, both rows are arranged close to each other, and the ink supply path 41 is arranged in each row of the plurality of channel grooves 31. In the case where the ink supply path 41 is formed, the cross-sectional area of the ink supply path 41 cannot be increased so much that bubbles and dust cannot stay in the ink supply path 41 for a long period of time. Since the ink is easily drawn into the channel groove 31 and stays in the channel groove 31, ink ejection failure is likely to occur. For this reason, it is important to be able to effectively remove the bubbles in the ink supply path 41.
[0086]
(3) Although the dummy grooves 32 are provided on both sides of each channel groove 31 in the above embodiment, the dummy grooves 32 may be omitted and only the channel grooves 31 may be adjacent to each other.
(4) In the above embodiment, the inkjet head 600 is applied to a printer that reciprocates with the carriage 504. However, the inkjet head 600 may be applied to a so-called line printer in which the inkjet head 600 is fixed to the main body of the color inkjet printer 1.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating a schematic configuration of a color inkjet printer including an inkjet head according to an embodiment of the present invention.
FIG. 2 is a perspective view illustrating an inkjet head according to an embodiment.
FIG. 3 is a perspective view illustrating a state where a sealing material is removed from the inkjet head according to the embodiment.
FIG. 4 is a partial longitudinal sectional view of an ink jet head according to an embodiment.
FIG. 5 is a perspective view illustrating a state in which a part of each substrate in the inkjet head according to the embodiment is viewed from the front end side.
FIG. 6 is a cross-sectional view of an inkjet head according to an embodiment.
FIG. 7 is an exploded perspective view illustrating a state where a manifold member is removed from the inkjet head according to the embodiment.
FIG. 8 is a partial perspective view of a manifold member in the inkjet head according to the embodiment.
FIG. 9 is a partial plan view of a manifold member and a substrate in the inkjet head according to the embodiment.
FIG. 10 is a plan view of a manifold member in the inkjet head according to the embodiment.
FIG. 11 is a plan view of a manifold member in the inkjet head according to the embodiment.
FIG. 12 is an explanatory diagram for explaining the operation of the embodiment.
FIG. 13 is a cross-sectional view of an inkjet head of a reference example.
14A and 14B are a perspective view and a cross-sectional view of a manifold member in the ink jet head of the reference example.
FIG. 15 is a perspective view showing a connection state of the manifold member and the substrate from the back side.
FIG. 16 is an explanatory diagram for explaining the operation of the reference example.
FIG. 17 is an explanatory diagram for explaining the operation of a conventional embodiment.
[Explanation of symbols]
509 ... Ink cartridge 600, 700 ... Inkjet head
11, 12 ... Substrate 13, 14, 113, 114 ... Manifold member
15 ... Plate member 16 ... Nozzle plate 16a ... Nozzle hole
22 ... Ink supply hole 24 ... Actuator 31 ... Channel groove
41, 141 ... Ink supply path 42 ... Opening forming member 45 ... Opening
114b ... tapered surface 151 ... connecting port 153 ... engaging portion EB ... bubble

Claims (4)

A plurality of channels are formed in an aligned state, and a substrate that ejects ink stored in each channel as droplets from nozzle holes provided on the outlet end side of the channel,
A manifold formed with an ink supply path formed of a recess that extends in an alignment direction of the plurality of channels and opens at an inlet end side of each channel and a side that is orthogonal to and parallel to the alignment direction;
A plate member fixed to the substrate and the manifold and covering an opening of the ink supply path on a side orthogonal to the inlet end of the channel, wherein the opening at the inlet side end of the channel of the ink supply path is the An inkjet head connected to an inlet end of a plurality of channels and supplying ink supplied from an ink supply source to the inlet end of each channel via the ink supply path;
The manifold is
A plurality of ink supply paths are provided along the opening end side of the inlet end side of the channel, and a flow path for introducing ink in the ink supply path of the manifold into each channel is provided between the channels. An opening forming member to be formed is provided to project from the bottom wall of the ink supply path facing the plate member toward the plate member,
The flow path between the opening forming members has a cross-sectional shape gradually narrowing from the opening end on the ink supply path side toward the channel,
An ink jet head, wherein bubbles contained in ink in the ink supply path are deformed so as to gradually approach the shape of at least two opposing sides of the inlet end of the channel. The inkjet head according to claim 1,
The inlet end of the channel has a shape in which one of two orthogonal widths is larger than the other, and the opening forming member has an opening end, and the two orthogonal widths are the two widths of the inlet end of the channel. An ink-jet head having a difference smaller than the difference between the two, and having a cross-sectional shape gradually narrowing from an opening end on the ink supply path side toward an inlet end of the channel. The inkjet head according to claim 1 or 2,
The opening end on the ink supply side of the flow path between the opening forming members has one width orthogonal to the alignment direction of the plurality of channels, of two orthogonal widths, and the alignment of the plurality of channels. An inkjet head characterized in that the shape is larger than the other width parallel to the direction, and the width of the latter gradually decreases toward the channel. The inkjet head according to claim 1 or 2,
The plurality of channels are formed in an aligned state in each row while forming a plurality of rows, and the ink supply path is formed along each row of the plurality of channels.

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