JP2882808B2 - Inkjet print head - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ink jet print head used for a multi-nozzle ink jet printer.

[Prior Art] Conventionally, as this type of ink jet printer, there is the following one. That is, as shown in FIG. 36, ink is introduced into a flow path 101 in the ink jet print head 100, and ink is jetted from a plurality of nozzles 102, 102... Provided in a longitudinal direction thereof as shown in FIG. Is to be sprayed. At this time, ultrasonic vibration is applied to the ink jet print head 100 by the ultrasonic vibrator 103 fixed to the back side of the flow path 101, and the ink is separated from the jet ink into droplets and ejected.
After the ink droplet D is charged by the charging electrode 104 in accordance with an image signal, the ink droplet D is deflected by the electric field of the deflecting electrode 105 to fly onto a recording paper (not shown).

However, in this case, an ultrasonic standing wave is formed by the vibrator 103 provided on the back side of the ink flow path 101 along the longitudinal direction of the head 100, and the standing wave of the ultrasonic wave forms a jet. Is separated from the ink droplet D. Therefore, the oscillating strength of the standing wave becomes non-uniform due to the dimensional error and non-uniformity of the material of the vibrator 103 and the head 100, and the position where the ink droplet D is separated is varied as shown in FIG. . Since the ink droplet D is charged by the charging electrode 104 at the moment when the ink droplet D is separated from the jet, if there is a large variation in the position where the ink droplet D is separated, there is a problem that an appropriate image cannot be printed. .

Further, in the print head 100, it is necessary to provide the vibrator 103 at a portion facing the flow path 101, so that the vibrator 103 and the nozzles 102, 102,... However, there is a drawback that the assembly of the apparatus is complicated, for example, care must be taken in sealing to prevent ink leakage.

Therefore, the present inventors have already proposed a device as disclosed in Japanese Patent Application No. 62-131789 as a solution to the above problem. As shown in FIG. 38, a cylindrical member 111 is formed by piercing a cylindrical through hole 110 along a longitudinal direction in a square material such as stainless steel to form a cylindrical body 111, and a small body is formed on one of its surfaces at predetermined intervals. A large number of holes 112 are formed. Are formed on the surface of the cylindrical body 111 where the small holes 112, 112 are formed.
Are fixed at a pitch equal to that of the nozzle plate 114 by means of bonding or the like. Further, an ultrasonic vibrator 115 is arranged at one end of a through hole 110 formed in the cylindrical body 111, and an ultrasonic absorber 116 is provided at the other end.
Place. Then, an ultrasonic traveling wave is applied to the ink flowing in the through-hole 110, and the ink is separated from the ink jet ejected from each of the nozzles 113, 113 into ink droplets.

In the print head using the traveling wave shown in the prior art, it is possible to stably and uniformly generate drops.

[Problems to be Solved by the Invention] However, the above-mentioned conventional proposed device has the following problems. That is, in the case of the above print head, it is necessary to provide a long through hole 110 along the longitudinal direction in a square material such as stainless steel and to form the cylindrical body 111. It is necessary, and there is a problem that manufacturing is difficult and cost is high. Also, a step of forming small holes 112, 112,... In the manufactured cylinder 111 and bonding the nozzle plate 114 is required, which causes a problem that the manufacturing process is complicated and the cost is increased.

In order to avoid such complicated processing, it is conceivable to form a nozzle directly in a cylinder and use it as an ink flow path. However, in such a case, in order to maintain the mechanical strength of the cylinder, it is necessary to use a thick cylinder, which makes it difficult to form the nozzle and makes it impossible to form the nozzle with high accuracy. Is newly generated. Conversely, it is conceivable to use a thin cylinder, but in such a case, it is difficult to maintain the strength of the cylinder, it is difficult to use the cylinder stably for a long time, and the reliability is lacking. Is newly generated.

Means for Solving the Problems Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, and an object thereof is to form a nozzle easily and accurately. Can,
Moreover, an object of the present invention is to provide an ink jet print head which can be used stably for a long period of time and has excellent reliability.

That is, the present invention has a plurality of nozzles, and in an ink jet print head which continuously ejects ink from these nozzles, a plurality of nozzles are directly drilled along the longitudinal direction, and ink can be introduced into the inside. Thick
A thin-walled cylinder having a thickness of less than 100 μm is provided, and a holding member for holding the thin-walled cylinder in close contact with an outer peripheral surface of a cylindrical portion provided with at least a plurality of nozzles is provided. In addition to the arrangement, means for absorbing ultrasonic waves is arranged on the other end side.

As the thin cylinder, for example, a cylinder formed of nickel by an electroforming method is used.
However, the present invention is not limited to this, and it can also be formed by mechanically processing a thin-walled cylinder by an electro-discharged machining (EDM) method or the like. In this case, it is easy to select a material having strong corrosion resistance as the material of the thin cylinder.

The material of the thin cylinder is not particularly limited, but is preferably as acoustically hard as possible so that sound pressure is not absorbed. For example, nickel, a nickel alloy, stainless steel or the like is used.

As the holding member, for example, a member made of a member for holding the front and rear and both ends of the thin cylinder is used, and these holding members are provided with a concave portion or a through hole for fitting and holding the thin cylinder. However, as described above, it is not always necessary to form the holding member from the four members that hold the front and rear and both ends of the thin cylinder. For example, the member that holds the front and rear may be formed integrally.

Further, as the holding member, a relatively thick cylinder covering the outer periphery of the thin cylinder may be used.

The holding member is assembled by screwing or the like, but is not limited to this, and may be combined with screwing and bonding using an epoxy resin adhesive, or by laser welding epoxy resin. Alternatively, all may be bonded with epoxy resin without using screws.

[Operation] In the present invention, the nozzle can be easily formed by forming the nozzle into a thin cylinder, and the mechanical strength of the thin cylinder is reinforced by holding the outer periphery of the thin cylinder with a holding member. , To withstand long-term use.

[Embodiments] The present invention will be described below based on the illustrated embodiments.

FIG. 9 shows an ink jet printer to which the ink jet print head according to the present invention can be applied. In the drawing, reference numeral 1 denotes an ink jet print head.
Ink is introduced from a pump (not shown) through an introduction hole 2, and ink droplets D are ejected from a plurality of nozzles 3, 3,... Provided in the longitudinal direction. After a predetermined charge is charged by the charging electrode 4 in accordance with the image signal, the ink droplet D is deflected by the electric field generated by the deflecting electrode 5 and flies to the recording paper (not shown), and flies on the recording paper. To print an image. In the drawing, reference numeral 6 denotes a discharge hole for discharging ink as needed.

One embodiment of the ink jet print head according to the present invention is configured as shown in FIG. The ink jet print head 1 includes a thin cylinder 7, and a large number of nozzles 3, 3,... Are formed in the thin cylinder 7 along the longitudinal direction. The thin cylinder 7 is
For example, the nozzles 3, 3,... Are formed at the same time when the thin-walled cylinder 7 is formed. According to this electroforming method, a very thin cylinder can be accurately formed. The thin cylinder 7 preferably has a thickness in the range of 20 to 30 μm, and for example, a cylinder having a thickness of 25 μm is used. The diameter of the thin-walled cylinder 7 is arbitrary, but a smaller diameter corresponds to a higher-frequency ultrasonic wave propagating inside the cylinder 7 as described later. Therefore, the diameter of the thin cylinder 7 is set according to the pitch of the nozzles 3, 3,... Determined by the frequency of the ultrasonic wave used. For example, a thin cylinder 7 having an inner diameter of 5.0 mm and an outer diameter of 5.05 mm is used. Further, the diameter of the nozzles 3 formed in the thin cylinder 7 is determined by the pressure of the ink introduced into the cylinder 7. The printing speed is determined by the printing speed and the like, but is set to, for example, 15 μm.

The circumference of the thin cylinder 7 is held by a holding member 8, and the holding member 8 is formed by machining a metal material. This holding member 8 is
As shown in FIG. 3 and FIG. 3, front and rear holding members 9 and 10 for holding the front and rear of the thin cylinder 7 and, as shown in FIGS. 1 and 4, both end holding members 11 and 12 for holding both ends. It is composed of As shown in FIG. 2, the rear holding member 10 is formed in a plate shape having a large thickness, and the rear holding member 10 has a diameter larger than the outer diameter of the thin cylinder 7 at the center of the front surface thereof. A semi-cylindrical recess 13 that is larger by the fitting margin is formed along the longitudinal direction.

The front holding member 9 is formed in a plate shape having a thickness substantially equal to half the outer diameter of the thin cylinder 7, and the front holding member 9 is divided into two upper and lower portions 9a and 9b. . The front side holding members 9a and 9b are larger at the lower end and upper end by the fitting allowance than the outer diameter of the thin cylinder 7, and are 1/1 / the outer circumference of the cylinder 7.
Concave portions 14 and 15 slightly shorter than 4 are formed. The reason why the recesses 14 and 15 of the front holding members 9a and 9b are slightly shorter than 1/4 of the outer diameter of the thin cylinder 7 is that the thin cylinder 7 is held by the front holding members 9a and 9b as shown in FIG. In this case, a gap G of about 1 mm is opened between the upper and lower holding members 9a, 9b, and the nozzles 3, 3,... Of the thin cylinder 7 are exposed from the gap G. Then, with the thin cylinder 7 fitted in the recess 13 of the rear holding member 10,
With the cylinder 7 covered by the recesses 14 and 15 of the front holding members 9a and 9b, the front holding members 9a and 9b are screwed to the rear holding member 10 as shown in FIG. , Holding the thin cylinder 7.

At both ends of the thin cylinder 7, both ends holding members 11,
There are twelve. The both end holding members 11 and 12 are fixed to the front holding members 9 and 10 together with mounting members 21 and 2 to be described later by screws (not shown) or the like. As shown in FIG. 5, the two end holding members 11 and 12
Through holes 17, 18 having diameters larger than the outer diameter of
The through holes 17 and 18 have thin cylinders 7
Are fitted and fixed with epoxy resin applied to the entire outer peripheral surface. In this manner, by preventing the ink from leaking, the thin cylinder 7 is fitted and fixed to the holding members 11 and 12 in a state where the epoxy resin is applied to the entire outer peripheral surface of the thin cylinder 7.

The length of the thin cylinder 7 is set to a value equal to the sum of the length of the front and rear holding members 9 and 10 and the length of both end holding members 11 and 12. The end surfaces of the holding members 11 and 12 match each other. Further, a groove 20 for fitting an O-ring 19 for sealing between the holding members 11 and 12 and an attachment member described later is formed in the outer end surfaces of the both end holding members 11 and 12.

As shown in FIG. 5, a means for introducing or discharging ink into the thin cylinder 7 and applying an ultrasonic wave to the introduced ink is attached to the outer ends of the both end holding members 11 and 12, as shown in FIG. The mounting members 21 and 22 are fixed.
Through holes 23 and 24 having the same diameter as the inner diameter of the thin cylinder 7 are formed in the mounting members 21 and 22 concentrically with the thin cylinder 7. The mounting member 21 is provided with an ink discharge hole 6 perpendicular to the through hole 23, and the mounting member 22 is provided with an ink introduction hole 2 perpendicular to the through hole 24. Has been drilled. Therefore, the ink introduced from the introduction hole 2 provided in the mounting member 22 flows through the through hole 24 into the thin cylinder 7 whose end is held by the both ends holding member 12. The ink flowing into the thin cylinder 7 is jetted from the nozzles 3, 3,. Further, the ink is discharged from the inside of the thin cylinder 7 to the outside from the discharge hole 6 through a through hole 23 provided in the mounting member 21 as necessary.

Further, an ultrasonic exciter 25 is attached to the outer end of the one attachment member 21 as shown in FIG. The ultrasonic exciter 25 is, as shown in FIG.
PZT ceramic 27, 28 so that it is sandwiched on both sides of 26
And pistons 29 and 30 made of SUS or the like are arranged, and are fixed to each other by bolts 31 penetrating these members. A shim 32 for mounting is sandwiched between the PZT ceramic 28 and the piston 30. Then, as shown in FIG. 6, a high frequency high voltage is applied to the electrode 26 by the power source P, and ultrasonic vibration is generated by the PZT ceramics 27 and 28, and the ultrasonic vibration is transmitted into the thin cylinder 7 by the piston 30. Is to be propagated. As shown in FIG. 6, the ultrasonic excitation vibrator 25 is mounted by fixing the mounting ring 33 to the mounting member 21 with a screw 34 in a state where the outer peripheral end of the shim 32 is clamped by the mounting ring 33. Also, at the opening end of the through hole 23 of the mounting member 21,
A groove 36 for fitting the O-ring 35 is formed. The O-ring 35 fitted in the groove 36 prevents ink from leaking at the end of the mounting member 21 and prevents the ultrasonic excitation The centering of the piston 30 is performed.

As shown in FIG. 8, the other mounting member 22 is provided with an ultrasonic absorber 37 for absorbing ultrasonic waves. The ultrasonic absorber 37 has a silicon rubber 38 having a tip 38a formed in a knife-edge shape, and the silicon rubber 38 causes no reflected wave with respect to an incident wave, and attenuates the incident ultrasonic wave. It is made to let. The silicone rubber 38 is fitted to the holding container 39,
The holding container 39 is fixed to the mounting member 22 with a screw 40. A groove 41 is formed in an inner end of the holding member 39 on the side of the mounting member 22, and an O-ring 42 for preventing leakage of ink is provided in the groove 41.

In the above configuration, printing is performed as follows in the ink jet print head according to this embodiment. That is, as shown in FIG. 1, ink is introduced into the ink jet print head 1 from the introduction hole 2, and the ink is jetted from a large number of nozzles 3, 3... Inject. that time,
Ultrasonic vibration is applied to the ink flowing in the thin cylinder 7 from the ultrasonic exciter 25, and the jet ink is separated into droplets and fly. The ultrasonic wave applied from the ultrasonic exciter 25 becomes a traveling wave and propagates in the thin cylinder 7, and is attenuated and absorbed by the ultrasonic absorber 37 in a state where the reflected wave is zero.

As shown in FIG. 9, the ink droplets D ejected from the nozzles 3, 3,... Are charged by the charging electrodes 4 according to the image signals, are deflected by the deflecting electrodes 5 and fly, and (Not shown) to print an image.

As described above, since the ink is separated into droplets by the traveling wave of the ultrasonic wave, the vibration and intensity of the ultrasonic wave applied to the ink become more uniform than before, and the ink becomes as shown in FIG. In addition, the length L from the nozzles 3, 3,... Until they are jetted and separated from each other as shown in FIG. 11, could be made much more uniform than in the conventional example. Therefore, the timing at which the ink droplet is charged by the charging electrode 4 becomes constant, and the ink droplet D is charged with a predetermined charge, so that an image can be printed with high quality.

The ink jet print head 1 according to this embodiment includes a thin cylinder 7 having a large number of nozzles 3, 3,...
In this case, it is not necessary to form a long hole in a metal square bar as in the related art, and the manufacturing can be easily performed. Since the nozzles 3, 3,... Can be easily formed in the thin-walled cylinder 7, a large number of nozzle holes are drilled in a square material as in the conventional case, and a nozzle plate having a nozzle formed on the surface thereof is further provided. Since it is not necessary to fix by adhesion or the like, it can be easily manufactured from this point as well. Also,
Even when the thin cylinder 7 is used, deformation of the thin cylinder 7 can be prevented by holding the outer periphery of the thin cylinder 7 with the holding member 8, and the diameter and positional accuracy of the nozzles 3, 3,. Thus, it can withstand long-term use.

FIG. 12 shows another embodiment of the present invention. The same parts as those in the above embodiment are denoted by the same reference numerals and described. Element
Rather than providing a concave portion 13 for holding a cylinder in 10, concave portions 14 and 15 are provided only in the front holding member 9. That is, the rear holding member 10 is formed in a flat plate shape whose thickness is not so large.
Is not provided. On the other hand, the front holding member 9
Is formed in a flat plate shape having a thickness substantially equal to the outer diameter of the thin cylinder 7. The front holding member 9 is divided into two upper and lower portions 9a and 9b in the same manner as in the above-described embodiment.
Recesses 14, 15 substantially equal to 2 are formed along the longitudinal direction. Then, as shown in FIG.
The two ends of the thin cylinder 7 are held at both ends,
After attaching both end holding members 11 and 12 to which the 22 is fixed, the thin cylinder 7 is held by fitting the thin cylinder 7 from both upper and lower sides so as to sandwich the thin cylinder 7 by the front holding members 9a and 9b. On the rear side of the thin cylinder 7, the end portions 9a 'and 9b' of the front holding members 9a and 9b overlap each other by about 1 mm in thickness.

In such a case, the recess provided in the holding member 8 is
Since only 4 and 15 are required and the recess can be easily formed,
The holding member 8 can be easily manufactured, and the manufacturing cost can be reduced. Other configurations and operations are the same as those of the above-described embodiment, and the description thereof will be omitted.

FIG. 14 shows still another embodiment of the present invention. The same portions as those in the above embodiment are denoted by the same reference numerals and described. In this embodiment, a rear holding member is used. However, the thickness of the front-side holding member is formed thicker by that amount. That is, the front holding member 9 is formed to have a thickness substantially equal to or a little thinner than the combination of the front and rear holding members 9 and 10 of the above-described embodiment.
It is divided into two upper and lower parts 9a and 9b. Concave portions 14 and 15 for fitting the thin-walled cylinder 7 are formed in the front end facing surfaces of the front holding members 9a and 9b.
When 9a and 9b are fixed to each other, a gap G is provided at the center of the front end.
Is formed. In such a case, the step of forming the concave portion in the holding member becomes easy as in the above-described embodiment, and the number of parts of the holding member 8 can be reduced, which also enables cost reduction. Other configurations and operations are the same as those of the above-described embodiment, and the description thereof will be omitted.

FIG. 15 shows still another embodiment of the present invention. The same portions as those of the above embodiment are denoted by the same reference numerals and described. In this embodiment, the front and rear holding members 9, 10
Are formed integrally with each other to form a main holding member 43, and a concave portion 44 for fitting the thin-walled cylinder 7 is formed in the front central portion of the main holding member 43 along the longitudinal direction. In this case, although it is somewhat difficult to form the recess 44, the number of parts can be further reduced, and the cost can be further reduced. Other configurations and operations are the same as those of the above-described embodiment, and the description thereof will be omitted.

FIG. 16 shows still another embodiment of the present invention. The same parts as those of the above embodiment are denoted by the same reference numerals and described. In this embodiment, the outer periphery of a thin cylinder is relatively thick. It is configured to cover and hold a meat cylinder.

As shown in FIG. 17, the ink jet print head 1 includes a thin cylinder 7, and a large number of nozzles 3, 3,... The holes are formed at a predetermined pitch according to the recording density.

The thin cylinder 7 is manufactured by, for example, drawing a metal cylinder. That is, as shown in FIG. 18, a stainless steel (for example, SUS30
3, 304), a cylinder 45 made of a metal such as nickel or chrome is fitted to the inner peripheral precision die 46a, and the outer periphery of the metal cylinder 45 fitted to the inner peripheral precision die 46a is attached to the outer peripheral precision die 46b. By pulling out the distal end side of the metal cylinder 45 in a state where the cylinder 47 is fitted, a thin-walled cylinder 47 is formed. Then, the above-mentioned drawing process is repeated a plurality of times as necessary, thereby producing a thin-walled cylinder 7 having a predetermined thickness, inner diameter and outer diameter. The thickness of the thin cylinder 7 is set to, for example, 25 μm.

The inner diameter of the thin cylinder 7 is arbitrary, but the smaller diameter corresponds to the higher frequency of the ultrasonic wave as described above. As the thin cylinder 7, for example, the inner diameter is 3.00 mm,
An outer diameter of 3.05 mm is used, but is not limited to this.

The thin cylinder 7 is, as shown in FIGS. 19 and 20,
The periphery thereof is covered and held by a thick cylinder 48 compared to the thin cylinder 7. This thick cylinder 48 is formed of the same material as the thin cylinder 7 by the same EDM processing or photo etching processing. Also, the above thick cylinder
48 has a thickness of, for example, 100 μm, and an inner diameter of, for example, 3.06 mm.

Further, as shown in FIG. 19,
For example, small holes 49 having a diameter of 1 mm are formed by etching or the like at a predetermined pitch according to the recording density of the nozzles 3, 3,.

To cover the thick cylinder 48 with the thin cylinder 7, as shown in FIG. 21, a core metal 50 is fitted and fixed to the thin cylinder 7, and an anaerobic adhesive is applied to the outer peripheral surface of the thin cylinder 7. 51
In the state where is applied, this thin-walled cylinder 7 is
As shown in the figure, it is covered and fixed by fitting it into a thick cylinder 48. The uncured anaerobic adhesive 51 attached to the small holes 49 of the thick cylinder 48 is wiped off with a cloth impregnated with alcohol or the like.

As shown in FIG. 24, the thin cylinder 7 covered with the thick cylinder 48 is fitted into the concave groove 53 formed in the holding member 52, and the adhesive 54 such as an epoxy resin. Fixed by On the front surface of the holding member 52, two holding plates 55, 55 for holding the thick cylinder 48 are screwed. The front surfaces of the holding plates 55 are aligned with the front end positions of the nozzles 3, 3,..., And when the charging electrodes 4, 4,. ,... And the charging electrodes 4, 4,. Further, as shown in FIG. 25, the thick and thin cylinders 49 and 7 are fitted with a cored bar, and the ink introduction holes 57 and the ink discharge holes 58 are provided at both ends of the thick and thin cylinders 49 and 7, respectively. Are drilled.

Next, as shown in FIG. 23, the thin cylinder 7 covered with the thick cylinder 48 is provided with the nozzles 3, 3 at the centers of the small holes 49, 49,. ... is drilled. The diameter of the nozzles 3, 3,... Is set to, for example, 15 μm, but is not limited thereto. When the nozzles 3, 3,... Are formed by electric discharge machining, the diameter of the nozzles 3, 3,... May vary depending on the thickness of the material. Are sufficiently thin as 25 μm, the nozzles 3 can be formed with high accuracy.

The thick and thin cylinders held by the holding member 52
As shown in FIG. 25, mounting members 59 for introducing and discharging ink into the thin cylinder 7 and attaching means for applying ultrasonic waves to the introduced ink are provided at both ends of 49 and 7. , 60 are installed. This mounting member
59 and 60 are formed thicker than the holding member 52, and the front end surfaces of the mounting members 59 and 60 project forward from the front end surface of the holding member 52. The mounting members 59 and 60 are
26, as shown in FIG.
A screw 59b is fixed via a, 59a.

As shown in FIGS. 27 and 28, the through holes 61 and 62 having a diameter slightly larger than the outer diameter of the thick cylinder 49 are formed in the mounting members 59 and 60. Both ends of the thick-walled cylinder 49 are fitted and fixed to the through holes 61 and 62 with the outer periphery thereof coated with epoxy resin. By applying the epoxy resin to the entire outer peripheral surface of the thin cylinder 7 in this manner, it is possible to prevent ink leakage.

In this mounting member 59, an ink discharge hole 6 is formed so as to be orthogonal to the through hole 61, and the other mounting member is provided.
The ink introduction hole 2 is formed in the 60 so as to be orthogonal to the through hole 62. Then, with the attachment members 59, 60 attached to both ends of the thick and thin cylinders 49, 7, the thick and thin cylinders 49,
7, ink introduction holes 57 and ink discharge holes
The ink introduction hole 2 and the ink discharge hole 6 formed in the attachment members 59 and 60 are aligned with each other.

Therefore, the ink introduced from the introduction hole 2 provided in the attachment member 59 flows through the through-hole 62 into the thin cylinder 7 whose end is held by the holding member 52. The ink flowing into the thin cylinder 7 is
3 ... jetted out. Further, the ink is discharged from the inside of the thin cylinder 7 to the outside through the through hole 61 provided in the mounting member 60 as necessary.

Further, an ultrasonic exciter 25 is attached to the outer end of the one attachment member 59 as shown in FIG. As shown in FIG. 27, this ultrasonic exciter 25 is basically configured in the same manner as that shown in FIG. That is, as shown in FIG. 29, the ultrasonic exciter 25 has a disc-shaped PZT ceramic 27, 28, which is sandwiched between both ends of a disc-shaped electrode 26, and a circle made of SUS or the like. Column-shaped pistons 29 and 30 are arranged, and these members are formed by filling the gaps with vacuum grease to ensure the sound-drop-like adhesion, and then pressing and fixing each other with bolts 31 penetrating therethrough. The torque of the bolt 31 is set to, for example, 10 kg / cm ² .

A shim 32 for mounting is sandwiched between the PZT ceramic 28 and the piston 30. Shims for this installation
As the 32, for example, a stainless steel plate having a thickness of about 0.1 to 0.3 mm is used, but is not limited thereto, and may be made of a synthetic resin, rubber, or the like. However, since the shim 32 needs to transmit the vibration of the PZT ceramics 27 and 28 to the piston 30, it is necessary to consider this point. The shim 32 also functions as a support member that attenuates the vibration of the ultrasonic exciter 12 and prevents the vibration from being transmitted to the head body 7. That is, when the shim 32 is formed of stainless steel or the like, the vibration transmitted to the mounting members 59 and 60 can be attenuated to some extent by setting the thickness to be thin.

As shown in FIG. 30, the electrode 26, the PZT ceramics 27 and 28, the piston 29 and the shim 32 are provided with an insertion hole 23 for passing a bolt 31, and the piston 30 is provided with a bolt 31. A female screw 30a for screwing the tip of the thread is screwed. Further, a cylindrical insulating rubber 31a is wound around the bolt 31 to avoid electrical contact with the electrode 26.

By the way, in this embodiment, in addition to the above-described configuration, a housing portion 65 for housing a piston member is provided at an end of the mounting member, and the cross-sectional shapes of the piston member and the piezoelectric vibrator are made smaller than the cross-sectional shape of the ink flow path. Is set large, and the distal end portion of the piston member disposed inside the housing portion 65 is formed to be thin so as to correspond to the cross-sectional shape of the thin cylinder 7.

That is, the diameters of the electrodes 26, the PZT ceramics 27 and 28 and the pistons 29 and 30 are set to be much larger than the diameter of the thin cylinder 7 as shown in FIG. As shown in FIG. 31, the piston 30 located in the housing portion 65 is formed stepwise from a concentrically located base end portion 30a and a distal end portion 30b. The base end 30a is
It is formed in a cylindrical shape with the same diameter as
30b is formed in a column shape whose diameter is slightly smaller than the inner diameter of the thin-walled cylinder 7. The inner diameter of the thin cylinder 7 is, for example, 3 m
In the case of m, the diameter of the tip portion 30b is set to, for example, 2.8 mm.

As shown in FIG. 31, the piston 30
a ′, 30a ″ are set as nodes of vibration, and the end surface 30b ′ of the distal end portion 30b is set to vibrate as an antinode of vibration. Therefore, the base end portion 30a of the piston has a length L _1. 1/2 of ultrasonic
Equal to the wavelength, the tip portion 30b is 1/4 a length L ₂ of the ultrasonic
It is set to be equal to the wavelength. For example, for a print frequency of 200 KHz, the speed of sound in stainless steel is 5000 m /
If sec, one wavelength is 25 mm, the length L ₁ of the base end 30a of the piston is 12.5 mm, and the length L ₂ of the tip 30b is 6.25.
mm. But actually, the piston
Since 30 etc. is fixed by bolt 31, piston
The wavelengths of the ultrasonic waves in 29 and 30 do not completely match the above values. Therefore, it is desirable to make some corrections through experiments. The length of the piston 29 is determined in consideration of the balance of vibration with the piston 30.

As shown in FIG. 27, the mounting member 59 has a housing portion for housing the piston 30 at the end on the ultrasonic exciter 25 side.
65 are provided. The accommodation portion 65 is set slightly larger in diameter and length than the base end portion 30a of the piston 30. As a result, the piston 30 has its base end 30a
5, the tip portion 30b is accommodated in the thin cylinder 7 so as to freely vibrate. Thus, the piston 30
Has an acoustically floating structure in the mounting member 59 without contacting the mounting member 59. Therefore, the piston 30 can freely vibrate in the mounting member 59 along the length direction with the predetermined position as a node and an antinode.

The ultrasonic exciter 25 includes a shim 32 as shown in FIG.
In a state where the outer periphery of the mounting ring 33 is clamped by the mounting ring 33, the mounting ring 33 is attached to the mounting member 59 by screws 66, 66... As shown in FIG. This mounting ring 33
Is formed in the same shape as the side surface shape of the mounting member 59,
At the center thereof, an opening 67 for inserting the piston 29 is provided. The opening 67 is preferably small in order to securely fix the shim 32, but since it is necessary to connect a lead wire for applying a drive voltage to the electrode 26 to the ultrasonic exciter 25, Space is required.

At the open end of the mounting member 59, as shown in FIG. 27, a fitting groove 36 for fitting the O-ring 35 is formed. By ring 35,
The leakage of the ink at the end of the attachment member 59 is prevented.

In the ultrasonic exciter 25, the electrode 26 is connected to a power source 70 via a lead wire 69, as shown in FIG. Therefore, a high frequency voltage is applied to the electrode 26 by the power supply 70, the ultrasonic vibration is generated by the PZT ceramics 27 and 28, and the ultrasonic vibration is propagated into the thin cylinder 78 by the piston 30. FIG. 33 shows the relationship between the frequency of the applied voltage and the amplitude of the ultrasonic vibration. The applied voltage can take a large amplitude at a somewhat low voltage, and if set to the peak of the vibration, the vibration becomes unstable. Therefore, the drive frequency F is set near the peak.

As in this embodiment, the piston 30 and the PZT ceramics 27, 28 are formed by forming the piston 30 into a stepped shape.
The diameter of the cylinder can be larger than the inner diameter of the thin cylinder 7, the amplitude of the ultrasonic vibration can be increased, and the ultrasonic vibration can be amplified by making the piston 30 stepped. It can be provided in the cylinder 7.

Also, as shown in FIG. 28, the other mounting member 60 has
An ultrasonic absorber 37 similar to that of the above embodiment is provided.
Since the configuration of the ultrasonic absorber 37 is the same as that of the above-described embodiment, the description thereof will be omitted.

In the ink jet print head according to this embodiment, since the outer periphery of the thin cylinder is configured to be covered and held by a relatively thick cylinder, non-uniform external and internal forces do not act on the thin cylinder. It is possible to prevent the cylinder from being mechanically warped or deformed. Therefore, it is possible to generate ink droplets that are stable with respect to the environment such as time and temperature change by using the thin cylinder. In addition, since the thin cylinder is covered with the thick cylinder, it is not necessary to handle only the thin cylinder when assembling the print head. Therefore, the handling of the thin cylinder becomes easy, and the head 1 can be easily assembled. Can be.

FIG. 34 shows still another embodiment of the present invention. The same parts as those of the above embodiment are denoted by the same reference numerals and described. In this embodiment, the embodiment shown in FIG. Unlike the above, the holding plate is not provided on the front surface of the holding member, and at both ends of the thick-walled and thin-walled cylinders, the mounting member is not fixed by epoxy resin to prevent the leakage of the ink. Is configured to prevent leakage. That is, the holding member
As shown in FIG. 35, a holding plate is not provided on the front face of 52, and the front face of the holding member 52 is
The positions of 3 ... coincide with each other.

In addition, as shown in FIG. 34, through holes slightly larger than the outer diameter of the thick cylinder are formed in the mounting members 59, 60 provided at both ends of the thick and thin cylinders 49, 7. In addition, a concave groove 71 for fitting an O-ring 70 is formed in the inner surface of the through hole. The O-ring 70 prevents ink from leaking between the attachment member 59 and the thick cylinder 49.

In such a case, since the holding plate can be omitted, the number of parts can be reduced. Further, by preventing the ink leakage between the mounting member 59 and the thick cylinder 49 by the O-ring 70, the fine cylinder 49 can be finely moved compared to the case where the thick cylinder 49 is fixed with epoxy resin. The dimensional accuracy in the length direction of the thick and thin cylinders 49 and 7 can be given a margin.

Other configurations and operations are the same as those of the above-described embodiment, and the description thereof will be omitted.

[Effects of the Invention] The present invention has the above configuration and operation, and has the following effects.

(1) Since the nozzle is formed in a thin cylinder, the nozzle can be formed with high precision, and when used as a head of an ink jet printer, uniform ink droplets can be stably and reliably generated. As a result, a recorded image with high definition can be obtained.

(2) Since the outer periphery of the thin cylinder is held by the holding member, sufficient strength as the head can be obtained even when the head is formed using the thin cylinder, and it is suitable for long-term use or environmental changes. On the other hand, mechanical deformation can be prevented, and the reliability is excellent.

(3) Since the thin cylinder having a plurality of nozzles is held by the holding member, a charging electrode or the like usually provided in front of the nozzles can be attached to the holding member, so that assembly of the printer and the like can be easily and accurately performed. Can do it.

(4) Since the thickness of the cylinder provided with the nozzle is thin, the pressure loss of the ink is small, and the ink can be satisfactorily ejected even when the pressure of the ink ejected from the nozzle is reduced. Therefore, it is possible to reduce the capacity of the pump for feeding the ink into the head.

(5) Since the ink flows directly in the thin cylinder and the nozzle is directly provided in the thin cylinder, there is almost no obstacle to the ultrasonic wave propagating in the thin cylinder for generating ink droplets, and the ultrasonic wave is mechanically transmitted. Since it is hardly affected by the target structure, the state of ink droplet generation can be made uniform.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing an embodiment of an ink jet print head according to the present invention, and FIG.
FIG. 3 is an exploded perspective view of the same device, FIG. 4 is an exploded front view of the same device, FIG. 5 is a cross-sectional view taken along line VV of FIG. 2, and FIG. 7 is an exploded front view showing the ultrasonic exciter, FIG. 8 is a cross-sectional view showing the ultrasonic exciter absorption side in FIG. 5, and FIG. 9 is the present invention. Schematic diagram showing an ink-jet printer to which the ink-jet print head according to the present invention can be applied, FIG. 10 is an explanatory diagram showing the separation state of ink droplets, FIG. 11 is a graph showing the separation length of ink droplets, FIG. Sectional view showing another embodiment,
FIG. 13 is a sectional view showing a state in the middle of assembling of the same embodiment, and FIG.
FIGS. 15 and 15 are sectional views showing different embodiments of the present invention, FIG. 16 is an exploded perspective view showing still another embodiment of the present invention, FIG. 17 is a perspective view showing a thin cylinder, and FIG. The figure is a cross-sectional view showing the manufacturing process of a thin cylinder, FIG. 19 is a perspective view showing a thick cylinder, FIG. 20 is a perspective view showing a state in which a thin cylinder is covered with a thick cylinder, and FIG. 21 is a thin cylinder. FIG. 22 and FIG. 23 are cross-sectional views showing the same state, respectively.
FIG. 25 is a front view of main parts of the print head, FIG. 26 is an exploded perspective view of main parts of the print head, FIGS. 27 and 28 are cross-sectional views showing both ends of the print head, FIG. 29 and FIG. FIG. 30 is an exploded perspective view and an exploded sectional view of an ultrasonic exciter,
FIG. 31 is an explanatory view showing a piston of an ultrasonic exciter, FIG. 32 is a side view showing an attached state of the ultrasonic exciter, FIG. 33 is a graph showing a driving frequency of the ultrasonic exciter, FIG. No. 35
FIG. 14 is a cross-sectional view and a cross-sectional view, partially broken away, showing still another embodiment of the present invention. FIG. 36 is a cross-sectional view showing a conventional ink-jet printhead. FIG. 38 is a sectional view showing another conventional example. [Explanation of Symbols] 1 ... Inkjet printer head 2 ... Introduction hole 3 ... Nozzle 7 ... Thin cylinder 8 ... Holding member 11, 12 ... Front and back holding member 21,22 ...

Continuation of front page (56) References JP-A-63-296957 (JP, A) JP-A-58-8656 (JP, A) JP-A-53-117334 (JP, A) JP-A-57-163576 (JP) JP-A-55-65571 (JP, A) JP-A-63-113651 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 2/02

Claims (1)

(57) [Claims] In an ink jet print head having a plurality of nozzles and continuously ejecting ink from these nozzles, a plurality of nozzles are directly formed in a longitudinal direction and ink can be introduced into the inside. A thin-walled cylinder having a thickness of less than 100 μm is provided, and a holding member for holding the thin-walled cylinder in close contact with an outer peripheral surface of a cylindrical portion provided with at least a plurality of nozzles is provided, and an ultrasonic wave is emitted to one end of the thin-walled cylinder An ink jet print head comprising: means for arranging ultrasonic waves; and means for absorbing ultrasonic waves on the other end side.