JPH0776090A - Nozzle of ink jet printer - Google Patents

Abstract

PURPOSE:To restore required capacity by rapidly disassembling an exciting part in the case of damage to replace a damaged part by connecting the piezoelectric element and resonator constituting the exciting part in a freely detachable manner. CONSTITUTION:The exciting part 10 of mechanical resonance nozzles is constituted by attaching two piezoelectric elements 1 and a resonator 2 by a nut capable of easily disassembling/re-assembling both of them and attached to a body 20. The exciting part 10 is attached using a screw and clamped together with a covering engineering plastic part 30. When various parts containing the piezoelectric elements 1 are damaged, the exciting part can be easily disassembled and only a damaged part can be rapidly replaced. The resonance frequency of the exciting part 10 can be adjusted by changing the clamping force of the nut 3 and an ink jet printer having stable capacity is obtained without receiving the effect of the dimensional irregularity or individual difference of parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge control type ink jet printer, and more particularly to a nozzle structure which amplifies a vibration amount of a piezoelectric element by a mechanical resonance phenomenon and gives it as energy for atomizing ink.

[0002]

2. Description of the Related Art There is a charge control type ink jet printer as one of the devices for printing characters on a printing object without contact.
Among them, continuous type ink jet printers that constantly eject ink and deflect ink droplets when necessary to print are widely used as marking devices for cans, bottles, etc. because they are easy to handle higher speeds. . In such an ink jet printer, a piezoelectric element is mainly used as a vibration source, and as a method of amplifying the vibration amount, a fluid resonance method utilizing liquid column resonance, a method utilizing mechanical resonance phenomenon, or a displacement magnifying mechanism is used. The method is used. Among them, the method utilizing mechanical resonance phenomenon is
It is characterized by being less susceptible to changes in the physical properties of ink due to changes in environmental temperature. As one example, for example, Japanese Patent Laid-Open No.
As seen in No. 501494, by mechanically resonating and amplifying a minute amount of vibration of a piezoelectric element that is a vibration source, ink can be efficiently made into particles, that is, at a low voltage. As can be seen in this example, the excitation part, which is usually composed of a piezoelectric element that is a vibration source and a resonator that is a vibration amplification means, is thermally or chemically attached, such as by solder bonding or adhesive connection, and semi-permanently. I try not to separate them. This method has an advantage that the number of manufacturing steps is small and thus the reliability is high, and the number of parts is small, so that it can be manufactured at a low cost.

[0003]

However, with the mounting method using solder or an adhesive, the excitation part including the piezoelectric element and the resonator cannot be easily disassembled. Therefore, if the piezoelectric element or resonator loses the desired performance for some reason, it is difficult to limit the damaged part because the two are joined, and the entire excitation part must be replaced. It is uneconomical because even normal parts are discarded.

Further, in the conventional mounting method, a deviation of the resonance frequency (natural frequency) of the excitation part is expected due to the influence of the machining accuracy of the resonator, variations in manufacturing the piezoelectric element, and the like. It is difficult to set the resonance frequency of a large number of nozzles to the same value, and in mechanical resonance nozzles, the amplitude of the resonator tip becomes smaller as the distance from the resonance frequency increases, so deviations in the resonance frequency cause variations in nozzle characteristics. I will end up. In order to solve this, there is a method of adjusting the length of the entire excitation unit. However, it is practically difficult to lengthen the resonator to lower the resonance frequency, and it is possible to shorten the resonator to increase the resonance frequency, but the distance from the resonator tip to the orifice Is not practical because it becomes a factor for making the nozzle characteristics unstable.

The object of the present invention is to quickly disassemble the exciting part and replace the damaged part to remove the defective part when the exciting part loses its function as a nozzle for some reason, thereby improving the desired performance. It will recover. Another object of the present invention is to provide a stable ink jet printer in which variations in nozzle characteristics caused by factors such as variations in dimensional accuracy of components and individual differences are eliminated.

[0006]

In order to achieve the above object, in an ink jet printer utilizing a mechanical resonance phenomenon, a resonance is transmitted to ink by amplifying a vibration amount of a piezoelectric element which is a vibration source and a piezoelectric element. It is configured so that it can be decomposed without being thermally or chemically bonded to the child.

[0007]

By configuring as described above, even if various parts including the piezoelectric element are damaged, they can be easily disassembled, so that only the damaged part can be quickly replaced, and the effects of dimensional variations of parts and individual differences. An object of the present invention is to provide an ink jet printer having stable performance without being affected.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 3 shows an example of the structure of the excitation width part 10 of the conventional ink jet printer utilizing the mechanical resonance phenomenon. Mechanical resonance, as is well known, is a phenomenon in which the amplitude of the vibration system rapidly increases when the frequency of the periodic external force applied to the vibration system approaches the natural frequency of the vibration system.
As such a structure, for example, as disclosed in JP-A-62-501494, usually, the piezoelectric element 1 which is a vibration source and the resonator 2 which amplifies the vibration of the piezoelectric element 1 and transmits it to the ink are soldered. Alternatively, the excitation part 10 is formed by joining the parts with an adhesive or the like.
Are configured. With this structure, the manufacturing process and the number of parts are small, so that the reliability is high, and the number of parts is small, so that the structure can be manufactured at low cost.

However, since the excitation section 10 composed of the piezoelectric element 1 and the resonator 2 cannot be easily disassembled by the mounting method using solder or adhesive, the piezoelectric element 1 and the resonator 2 are expected to be undesired for some reason. If the performance is lost, they cannot be easily disassembled because they are joined. For this reason, it becomes difficult to limit the damaged part, and it is necessary to take measures to replace the entire excitation part, but this is uneconomical because even normal parts are discarded.

Further, it is expected that the resonance frequency of each nozzle will be shifted due to variations in the machining accuracy of the resonator 2. Generally, in the mechanical resonance nozzle, the amplitude becomes smaller as the distance from the resonance frequency increases, so that the deviation of the resonance frequency causes the variation of the nozzle characteristics as it is. Therefore, when excited at the same frequency, some nozzles have good performance, but there is a risk that some nozzles may not function as ink and the ink may not function as a printer.

The present invention solves the above problems and invents a structure and an assembling method for realizing a stable nozzle for an ink jet printer, and the contents will be described below. First, FIG. 1 shows an appearance of an embodiment of a nozzle for an inkjet printer of the present invention, and FIG. 2 is a sectional view thereof. In this example, a nut 3 that can easily disassemble and reassemble the two piezoelectric elements 1 and the resonator 2
The exciter section 10 of the mechanical resonance nozzle is configured by mounting with. The excitation unit 10 is attached to the body 20. The excitation part 10 is attached by using a screw, but it is also tightened together with the embra part 30 that covers the excitation part 10.

The ink flow path 4 penetrates through the embra part 30 and is fitted and fixed to the body 20 part. An adhesive material is applied to the ink flow path 4 so that the ink flow path 4 is fitted with good sealing properties.
The ink channel 4 is fixedly supported on the body 20 by the excitation unit 1.
0 and the embra part 30 are carried out before the body 20 part is attached for good workability in assembly.

The above-mentioned screw is inserted and tightened from the rear of the embra 30. With two screws of the same size,
Ensuring sufficient tightening is performed. Since the embra part 30 is fastened with screws, it can be easily disassembled and assembled and protects the piezoelectric element 1 from an external force such as an impact. Further, a part of the embler 30 is notched in order to attach a power source line for driving the piezoelectric element 1. However, in order to prevent ink from penetrating therethrough and short-circuiting the piezoelectric element 1, a coating agent is provided in the gap. Filling. In addition, it is necessary to use a coating agent having excellent solvent resistance and to prevent the vibration characteristics of the piezoelectric element 1 from being changed by the coating agent and impairing the nozzle characteristics. With such a structure, when the tightening force of the nut 3 is increased, the degree of adhesion at each contact surface is improved and the resonance frequency is increased, but when it is weakened, the resonance frequency can be decreased. Therefore, even if the resonance frequency is deviated due to variations in dimensional accuracy of parts or individual differences of the piezoelectric element 1, the resonance frequency can be easily adjusted to a desired value by adjusting the tightening force. In this example, two piezoelectric elements 1 are used, but the number of piezoelectric elements 1 may be set so that the energy necessary for atomizing the ink can be obtained, and the number is not limited to two. Not a thing.

With this structure, even if various parts including the piezoelectric element 1 are damaged, they can be easily disassembled.
The effect is that only the damaged part can be replaced promptly. In addition, since the resonance frequency of the excitation unit 10 can be adjusted by changing the tightening force of the nut 3, there is an effect that an inkjet printer having stable performance can be provided without being affected by variations in dimensions of parts and individual differences. is there. In addition, there is an effect that insulation failure due to ink invasion can be prevented.

Further, in the example of FIG. 1, the ink flow path 4 is arranged at the rear of the nozzle, and the overall shape of the nozzle is thin and flat in the vertical direction. This is for accommodating various parts such as the excitation unit 10, the charging electrodes, the deflection electrodes, the control signal wiring, and the various flow passages in a housing usually called a nozzle head (not shown), In particular, it is important to finely adjust the ejection direction of the ink beam to secure an adjustment allowance when moving in the height direction. Further, as the position at which the nozzle head portion for ejecting ink is mounted on the production line, there are many gaps in the conveyor and the like, and miniaturization of the nozzle head is an important issue. From this point of view, it can be said that the nozzle is also preferably flat in the vertical direction.

In the above example, the resonator 2 in contact with the body 20 has the same sectional shape as the body 20. FIG. 4 shows the detailed shape. 4 (a) shows the cross-sectional shape thereof, and FIG. 4 (b) is a front view of the resonator 2 (note that the four circles shown in the squares of FIG. 4 (b) are two. Are arranged so that the screw and the hole through which the two ink flow paths 4 penetrate each other form a slight glare.) With such a configuration, a sufficiently large contact area between the body 20 and the resonator 2 can be ensured, so that an effect that a stable close contact state can be obtained can be expected. However, the shape of the resonator 2 is not necessarily limited to this. For example, as shown in FIG. 5, the resonator 2 may have a circular shape and may be combined with the support component 7. In this example, the ink sealing function with the body 20 is performed by the collar portion of the resonator 2, and the piezoelectric element 1 is attached by the support member 7. Due to this two-part structure, the body 2
Since the resonator 2 can be shared regardless of whether the cross-sectional shape of 0 is circular or rectangular, it is effective to manufacture only the support component 7. Further, since the resonator 2 has a circular shape in its entirety, the resonator 2 can be manufactured with one type of machine tool such as a lathe, so that the resonator 2 can be manufactured at low cost. Further, FIG. 6 shows the resonator 2 and the support component 7.
This is an example of a configuration in which the support part 7 is divided into two parts and the ink sealing function with the body 20 and the attachment of the piezoelectric element 1 are all performed. In the case of such a configuration, the resonator 2 becomes extremely small, so that there is an effect that the cutting allowance is small and the resonator 2 can be manufactured in a short time and at a low cost.

Next, the ink chamber in the nozzle portion will be described. The ink atomized by the vibration of the resonator 2 is ejected through the orifice portion 40, but since the diameter is as thin as several tens to 100 μm, the orifice portion 40 is easily clogged with foreign matter. Further, when the apparatus is stopped for a long period of time, ink clogging may occur due to the effect of residual ink during the cleaning process. When ink clogging occurs, the product printed in the meantime becomes a defective product, so it is important to quickly eliminate the factor of clogging and restore it. In order to realize this, it is preferable to reduce the volume of the ink chamber so that the inside can be easily cleaned. The specific structure is shown in FIGS. Of these, FIG. 7 shows an example in which an O-ring groove for ink sealing is provided on the body 20 side, while FIG. 8 shows an example in which an O-ring groove is provided on the resonator 2 side. As shown in the drawing, the flow path 4 on the ink supply side is arranged near the orifice to facilitate cleaning, and the flow path 4 on the discharge side is also arranged near the orifice so that the removed foreign matter can be quickly discharged to the outside of the nozzle. The structure has the effect of making the ink chamber extremely small and easy to clean.

Although not shown, the orifice portion 40 is attached to the body 20 with a screw. An O-ring is sandwiched between the orifice portion 40 and the body 20 to prevent ink from leaking from the joint surface. Similarly, an O-ring is sandwiched between the body 20 and the resonator 2 to prevent ink from leaking from the joint surface.

Further, as mentioned above, with the miniaturization of the excitation unit 10, it is required to reduce the diameter of the resonator 2. This allows
The amount of deviation between the axial center of the tip of the resonator 2 and the axial center of the orifice 40 increases. If this amount of deviation increases, the resonator 2 comes into contact with the inner wall surface of the body 20 and the amount of vibration at the tip of the resonator 2 decreases, so that the function as a nozzle may be lost. As a countermeasure against this, as shown in FIG. 9, the rear edge of the resonator 2 is extended, and an O-ring is attached thereto to position the resonator 2, so that the axis of the resonator 40 and the axis of the resonator 40 are aligned with each other. . As a result, there is an effect that stable nozzle characteristics can be maintained even when the excitation unit 10 is downsized.

[0020]

According to the present invention, even if various parts including a piezoelectric element are damaged, the parts can be easily disassembled, so that only the damaged part can be quickly replaced.

Further, since the resonance frequency of the excitation part can be adjusted by increasing or decreasing the tightening force of the nut, it is possible to realize an ink jet printer having stable performance without being affected by dimensional variations of parts and individual differences. effective.

Further, since the resonators are all circular in shape, they can be machined with one type of machine tool such as a lathe.
There is an effect that it can be manufactured at low cost.

In addition, the flow path on the ink supply side is arranged near the orifice to facilitate cleaning, and the flow path on the discharge side is also arranged near the orifice so that the removed foreign matter can be promptly discharged to the outside of the nozzle. This makes the ink chamber extremely small and easy to clean. Furthermore, there is an effect that stable nozzle characteristics can be maintained even when the excitation unit is downsized.

[Brief description of drawings]

FIG. 1 is a vertical external view and a horizontal external view of an inkjet printer showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an inkjet printer showing an embodiment of the present invention.

FIG. 3 is a transverse cross-sectional view showing a conventional mechanical resonance type excitation unit.

FIG. 4 is a cross-sectional view showing a resonant solid according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view showing the shape of a supporting member of the present invention.

FIG. 6 is a cross-sectional view showing the shape of a supporting member of the present invention.

FIG. 7 is a cross-sectional view showing the ink seal structure of the present invention.

FIG. 8 is a cross-sectional view showing the ink seal structure of the present invention.

FIG. 9 is a cross-sectional view showing a method of setting the axis of the resonator of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric element, 2 ... Resonator, 3 ... Nut, 4 ... Ink flow path, 7 ... Supporting part, 10 ... Excitation part, 20 ... Body, 30
... Embra, 40 ... Orifice part.

[Procedure amendment]

[Submission date] November 2, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0005

[Correction method] Change

[Correction content]

The object of the present invention is to quickly disassemble the exciting part and replace the damaged part to remove the defective part when the exciting part loses its function as a nozzle for some reason, thereby improving the desired performance. Ru Oh to be restored. Another object of the present invention is to provide a stable ink jet printer in which variations in nozzle characteristics caused by factors such as variations in dimensional accuracy of components and individual differences are eliminated.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

[0007]

By configuring as described above, even if various parts including the piezoelectric element are damaged, they can be easily disassembled, so that only the damaged part can be quickly replaced, and the effects of dimensional variations of parts and individual differences. To provide an inkjet printer with stable performance without receiving
You can

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Figure 3 shows an example of the excited vibration portion 10 structure of an inkjet printer using a conventional mechanical resonant phenomena. As circumferential known, the frequency of the periodic external force to the resonance phenomenon applied to the vibration system is close to the natural frequency of the vibration system, the phenomenon that the amplitude of the vibration system is rapidly increased, as such structures , For example, as seen in JP-A-62-501494,
Usually, the excitation unit 10 is configured by joining the piezoelectric element 1 that is a vibration source and the resonator 2 that amplifies the vibration of the piezoelectric element 1 and transmits the vibration to the ink by means of solder or adhesive. With this structure, the manufacturing process and the number of parts are small, so that the reliability is high, and the number of parts is small, so that the structure can be manufactured at low cost.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kuniyoshi Tsubouchi 502 Jinritsucho, Tsuchiura City, Ibaraki Prefecture

Claims (4)

[Claims] 1. In a nozzle of an ink jet printer having an exciting section composed of a piezoelectric element which is a vibration source and a resonator which resonates by the vibration of the piezoelectric element, the piezoelectric element and the resonator are detachably coupled. A nozzle for an inkjet printer. 2. A nozzle for an ink jet printer according to claim 1, wherein the piezoelectric element and the resonator are detachably coupled with a screw. 3. A nozzle of an ink jet printer comprising an exciting section composed of a piezoelectric element which is a vibration source and a resonator which resonates by the vibration of the piezoelectric element, wherein a supporting section extending to the rear of the resonator is provided. A nozzle for an ink jet printer, characterized in that a piezoelectric element is detachably attached to this support portion. 4. A nozzle of an ink jet printer having an excitation part composed of a piezoelectric element which is a vibration source and a resonator which resonates by the vibration of the piezoelectric element, wherein a support rod extending to the rear part of the resonator is provided. A nozzle for an ink jet printer, characterized in that a piezoelectric element is fitted and supported on the support rod, and a nut is screwed into a screw formed on the support rod to fasten and fix the piezoelectric element to the resonator.