JP2002361143A - Fluid coating method and fluid coating device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In the production process in the field of electronic parts, home appliances, etc., various powder fluids such as adhesives, clean solder, phosphor, grease, paint, hot melt, medicine, food, etc., are powdered. The discharge can be shielded and started at high speed without squeezing or destruction. SOLUTION: A relative linear motion and a rotary motion are provided between a shaft and a cylinder, and a fluid transport means is provided by the rotary motion, and a relative gap between a fixed side and a rotary side is changed using the linear motion. In a coating device that controls the amount of fluid discharged, changing the rotation speed in any of the steps of coating start, coating, coating cutoff, and standby reduces the temperature rise of the coating material and reduces damage to the material. Aim for reduction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention can be used in production processes in the fields of electronic parts, home appliances, etc., and can be used for various liquids such as adhesives, cream solders, phosphors, greases, paints, hot melts, chemicals, foods, etc. Dispensing
The present invention relates to a fluid application for discharging and a device therefor.

[0002]

2. Description of the Related Art Liquid ejecting apparatuses (dispensers) have been used in various fields, but with the recent demand for miniaturization and high recording density of electronic components, a minute amount of fluid material can be dispensed with high precision. There is a demand for a technique for stably controlling discharge.

[0003] Taking the field of surface mounting (SMT) as an example,
In the trend of high-speed mounting, miniaturization, high-density, high quality, and unmanned mounting, the issues of dispensers can be summarized as follows: high accuracy of application amount and miniaturization of one application amount. Shorter: Can be used for high-viscosity powder fluids that can shut off and start high-speed discharge Conventionally, a dispenser of an air pulse type, a screw groove type, a micropump type using an electromagnetic strain element, or the like has been put to practical use in order to discharge a very small amount of liquid.

[0004]

Among the prior art examples described above, a dispenser using an air pulse method as shown in FIG. 8 is widely used.
The technology is introduced in “3.25, Issue 7” and the like. The dispenser according to this method causes a constant amount of air supplied from a constant pressure source to be applied to the container 200 (cylinder) in a pulsed manner, and causes a constant amount of liquid corresponding to a rise in the pressure in the cylinder 200 to be discharged from the nozzle 201. Things.

[0005] The air pulse type dispenser has a drawback that response is poor.

[0006] This disadvantage is due to the compressibility of the air 202 enclosed in the cylinder and the nozzle resistance when passing the air pulse through a narrow gap. That is, in the case of the air pulse method, the cylinder volume: C and the nozzle resistance: R
The time constant of the fluid circuit that can be achieved: T = RC is large, and after the input pulse is applied, a time delay of, for example, about 0.07 to 0.1 seconds from the start of ejection must be expected.

In order to eliminate the drawbacks of the air pulse method, a needle valve is provided at the inlet of the discharge nozzle.
A dispenser that opens and closes a discharge port by moving a small-diameter spool constituting the needle valve at high speed in an axial direction has been put to practical use.

However, in this case, when the fluid is shut off, the gap between the relatively moving members becomes zero, and the powder having an average particle diameter of several to several tens of microns is mechanically pressed and destroyed.

[0009] Due to various inconveniences caused as a result, it is often difficult to apply the method to the application of an adhesive material, a conductive paste, or a phosphor mixed with powder.

For the same purpose, a screw groove type dispenser which is a viscous pump has already been put to practical use. In the case of the screw groove type, a pump characteristic that is hardly dependent on the nozzle resistance can be selected, so that a preferable result can be obtained in the case of continuous spraying, but the intermittent application is not good in terms of the characteristics of the viscous pump. Therefore, in the conventional screw groove type, (1) an electromagnetic clutch is interposed between the motor and the pump shaft, and this electromagnetic clutch is connected or released when the discharge is turned ON or OFF.

(2) Use a DC servomotor to start or stop rapid rotation.

However, since the response is determined by the time constant of the mechanical system in any of the above cases, the high-speed intermittent operation is limited. The responsiveness is better than that of the air pulse method, but the shortest time is about 0.05 seconds.

In addition, since there are many uncertainties in the rotation characteristics of the pump shaft during transient response (at the start and stop of rotation), it is difficult to strictly control the flow rate, and the coating accuracy is limited.

For the purpose of discharging a small amount of fluid, a micropump using a laminated piezoelectric element has been developed. For this micro pump, a mechanical passive discharge valve or suction valve is usually used.

However, in the above-described pump which is constituted by a spring and a ball and opens and closes a discharge valve and a suction valve by a pressure difference,
It is extremely difficult to intermittently discharge a high-viscosity rheological fluid of tens of thousands to hundreds of thousands of centipoise with poor flowability at high flow rate accuracy and at high speed (0.1 seconds or less).

In the field of circuit formation, which is becoming increasingly more precise and ultra-fine in recent years, or in the fields of forming electrodes and ribs for picture tubes such as PDPs and CRTs, applying sealing materials for liquid crystal panels, and manufacturing processes for optical discs and the like. There are strong demands for fine coating technology as follows.

After continuous spraying, application can be stopped quickly and continuous application can be started rapidly after a short time. For that purpose, it is ideal that the flow rate can be controlled, for example, on the order of 0.01 second.

[0018] Capable of handling powder fluid. For example, there should be no troubles such as powder compression breakage or flow path clogging due to mechanical cutoff of the flow path.

In order to respond to various recent demands related to the above-described minute flow rate application of a high-viscosity fluid / powder fluid, the present inventors provide a relative linear motion and a rotational motion between a piston and a cylinder. Along with the rotation means to provide a means of transporting the fluid, using linear motion to change the relative gap between the fixed side and the rotation side, the coating means to control the discharge amount of the fluid,
Pending "Fluid supply device and fluid supply method" (Japanese Patent Application 2000
-188899).

The present invention is a further improvement of the above-mentioned proposal. By changing the rotational speed of the apparatus between the time when the fluid is cut off and the time when the fluid is applied, for example, the flow path is kept in a non-contact state and the fluid is shut off. In this case, the reliability is improved, for example, by reducing the damage to the semiconductor device.

[0021]

According to the fluid application method of the present invention, the axial drive is controlled so that the end face of the shaft on the discharge port side and the opposing face are increased when the fluid is applied, and the gap is reduced when the fluid is shut off. , Start of application, during application, application interruption,
It is characterized in that the number of revolutions is changed in any one of the steps in the standby process.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment in which the present invention is applied to a dispenser for surface mounting electronic components will be described.
This will be described with reference to FIG.

Reference numeral 1 denotes a first actuator. In the embodiment, in order to supply a high-viscosity fluid intermittently in a very small amount and with high precision at a high speed, a high positioning accuracy is obtained, a high responsiveness and a large response are obtained. A giant magnetostrictive element capable of obtaining a generated load was used.

Reference numeral 2 denotes a central axis driven by the first actuator 1. The first actuator is housed in the housing 3. A front-side main shaft 5 is supported by a housing 4 disposed at the lower end of the housing 3 so as to be rotatable and slightly movable in the axial direction. Reference numeral 6 denotes a piston (shaft) which is detachably attached by a front-side main shaft 5 and bolts 7 and is accommodated in a cylinder 8. The radial groove 10 is a fluid seal.

Between the piston 9 and the cylinder 8, there is formed a pump chamber 11 for obtaining a pumping action by the relative rotation of the screw groove 9 and its opposing surface. The cylinder 8 has a suction hole 12 communicating with the pump chamber 11. Reference numeral 13 denotes a discharge nozzle mounted on the lower end of the cylinder 8, and reference numeral 14 denotes a discharge unit including the discharge nozzle 13 described later.

Reference numeral 15 denotes a second actuator, which gives a relative rotational movement between the piston 6 and the cylinder 8. The motor rotor 16 is fixed to a rear main shaft 17, and the motor stator 18 is housed in a housing 19.

Reference numeral 20 denotes a cylindrical giant magnetostrictive rod composed of giant magnetostrictive elements, and reference numeral 21 denotes a magnetic field coil for applying a magnetic field in the longitudinal direction of the giant magnetostrictive rod 16. 22 and 23 are permanent magnets for applying a bias magnetic field to the giant magnetostrictive rod 20
a, b, which are arranged in such a manner as to honor the giant magnetostrictive rod 20 in the middle.

The permanent magnets 22 and 23 apply a magnetic field to the giant magnetostrictive rod 20 in advance to increase the operating point of the magnetic field.
With this magnetic bias, the linearity of giant magnetostriction with respect to the strength of the magnetic field can be improved. Reference numeral 24 denotes a rear yoke of a magnetic circuit which is arranged on the rear side of the giant magnetostrictive rod 20 and is integrated with the rear main shaft 17. The front-side main shaft 5 also serves as a yoke material of the magnetic circuit, and is disposed on the front side of the giant magnetostrictive rod 20. Reference numeral 25 denotes a cylindrical yoke member disposed on the outer peripheral portion of the magnetic field coil 21.

20 → 22 → 24 → 25 → 5 → 23 → 20
Thus, a closed loop magnetic circuit for controlling expansion and contraction of the giant magnetostrictive rod 20 is formed. The center shaft 2 is made of a non-magnetic material so as not to affect the magnetic circuit. That is, the giant magnetostrictive rod 20, the permanent magnets 22 and 23, and the magnetic field coil 21 constitute a giant magnetostrictive actuator (first actuator 1) capable of controlling the expansion and contraction of the giant magnetostrictive rod in the axial direction by a current applied to the magnetic field coil. .

The giant magnetostrictive material is an alloy of a rare earth element and iron. For example, bFe ₂ , DyFe ₂ , SmFe _{2 and the} like are known, and their practical use has been rapidly advanced in recent years.

The upper central shaft 17 is rotatably supported by a housing 27 by a bearing 26.

Reference numeral 28 denotes the front spindle 5 and the bearing sleeve 2.
9 is a bias spring mounted between the two. This bearing sleeve 29 is also rotatably supported by the housing 4 with respect to the housing 4. The giant magnetostrictive rod 20 is gripped by the upper and lower members 5 and 24 via the bias permanent magnets 22 and 23 by the axial load applied from the bias spring 28. As a result, the compressive stress is always applied to the giant magnetostrictive rod 20 in the axial direction, so that when a repetitive stress is generated, the defect of the giant magnetostrictive element which is weak against the tensile stress is solved.

Front spindle 5 integrated with piston 6
Is accommodated in the bearing sleeve 29 regulated by the bearing 30 so as to be movable in the axial direction.

The rotational power of the central shaft 2 transmitted from the motor 15 is transmitted to the front main shaft 5 by a rotation transmission key 31 provided between the central shaft 2 and the front main shaft 5. This rotation transmission key 31 transmits the rotational power,
It has a rectangular cross-sectional shape that is free in the axial direction (not shown).

With the above configuration, the rotational power of the motor 15 is transmitted only to the center shaft 2 and the front side 5, and no torsional torque is generated in the giant magnetostrictive element, which is a brittle material.

Reference numeral 32 denotes a motor 1 as a second actuator.
5 is an encoder for detecting the rotational position information of the upper central shaft 17 disposed above the fifth central shaft 5.

Reference numerals 33 and 34 denote a displacement sensor A and a displacement sensor B for detecting an axial displacement of the front side 5 (and the piston 6).

With the above configuration, in the fluid application apparatus of the present invention, the rotation of the piston 6 of the pump and the control of the linear movement with minute displacement can be performed simultaneously and independently.

Further, in the embodiment, since the giant magnetostrictive element is used as the first actuator, power for linearly moving the giant magnetostrictive rod 20 (and the piston 6) can be applied from outside without contact.

Since the input current applied to the giant magnetostrictive element is proportional to the displacement, the axial positioning control of the piston 6 is possible even with open loop control without a displacement sensor. However, if feedback control is performed by providing the position detecting means as in the present embodiment, the hysteresis characteristic of the giant magnetostrictive element can be improved, and positioning with higher accuracy can be performed.

In the present embodiment, it is possible to arbitrarily control the size of the gap on the discharge-side thrust end face of the piston 6 by using the axial positioning function of the piston 6 while keeping the piston 6 in a steady rotation state. it can. Using this function, the powder fluid can be shut off / opened in any flow passage section from the suction port 12 to the discharge nozzle 13 in a mechanically non-contact state. The principle will be described with reference to FIG.

In FIG. 2, reference numeral 35 denotes a discharge end face of the piston 6, and reference numeral 36 denotes a discharge plate fastened to the discharge end face of the cylinder 8. A thrust groove 38 for sealing is formed in a relative movement surface between the discharge side end surface 35 and the opposing surface 37 of the cylinder. An opening 39 of the discharge nozzle 13 is formed at the center of the opposing surface 37 of the thrust end surface 35.

The radial groove 11 already described with reference to FIG. 1 is a known groove known as a spiral groove dynamic pressure bearing, and is also used as a thread groove pump.
The pumping pressure generated by the thread groove pump is determined by the rotation angular velocity, shaft outer diameter, groove depth, groove angle, groove width and ridge width, and the like. Table 1 below shows the specifications of the thread groove pump used in the examples.

[0044]

[Table 1]

The sealing thrust groove 38 is also known as a thrust dynamic pressure bearing. Now,
Similarly, the seal pressure that can be generated by the thrust bearing is determined by the rotational angular velocity, the inner and outer diameters of the thrust bearing, the groove depth, the groove angle, the groove width and the ridge width, and the like.

The curve (a) in the graph of FIG.
Under conditions shown in Table 2 below shows the characteristics of the sealing pressure P _S of gap δ when using the spiral groove type thrust groove. The curve (b) in the graph of FIG. 3A is an example showing the relationship between the pumping pressure of the radial groove and the gap δ at the tip of the shaft when there is no axial flow. The pumping pressure of the radial groove can be selected in a wide range by selecting the radial gap, the groove depth, and the groove angle, similarly to the thrust groove. However, qualitatively, the pumping pressure Pr of the radial groove does not depend on the size of the gap at the tip of the shaft (that is, the size of the gap δ).

[0047]

[Table 2]

When the gap δ of the sealing thrust groove is sufficiently large, for example, when the gap δ is 15 μm, the generated pressure is small and P <0.98 MPa.

While the shaft is being rotated, the end surface of the rotating shaft is brought closer to the fixed-side facing surface. When the gap δ <10.0 μm, the sealing pressure becomes larger than the pumping pressure Pr of the radial groove, and the outflow of the fluid to the discharge port side is shut off.

FIG. 2 shows a state in which the outflow of the fluid is blocked. Since the fluid near the opening 39 of the discharge nozzle is subjected to a centrifugal pumping action [arrows in FIG. The vicinity of the opening 39 is at a negative pressure (atmospheric pressure or lower). Due to this effect, after shutting off, the discharge nozzle 13
The fluid remaining inside is sucked into the pump again. As a result, a fluid soul is not formed due to surface tension at the tip of the discharge nozzle, and stringing and dropping are eliminated.

In the embodiment of the present invention, ON / OFF of the discharge state of the fluid can be freely controlled by moving the rotating shaft in the axial direction by only about 5 to 10 μm.

To summarize the point of the present invention, the sealing pressure by the thrust groove increases sharply as the gap δ becomes smaller, whereas the pumping pressure of the radial groove is extremely insensitive to the change of the gap δ. , To take advantage of the point.

Any of the radial groove and the thrust groove may be formed on either the rotating side or the fixed side.

When a powder fluid such as an adhesive containing fine particles is applied, the minimum value δmin of the gap δ may be set to be larger than the fine particle diameter φd.

[0055]

(Equation 1)

To obtain a larger gap for the same generated pressure, the outer diameter of the flange 31 of the thrust seal may be increased, and appropriate values may be selected for the groove depth, groove angle, and the like.

The driving principles of the thread groove pump and the thrust seal used in the embodiment both use the dynamic pressure effect of a viscous fluid. That is, the gap of the narrow gap relatively moving,
The wedge pressure generated by the change in the moving direction is used.

Therefore, the pumping pressure Pr of the thread groove pump and the sealing pressure Ps of the thrust seal increase and decrease in proportion to the rotation speed. The present invention focuses on this point. For example, even if the pumping pressure Pr of the thread groove pump increases due to an increase in the number of revolutions, the sealing pressure of the thrust seal also increases.
Since Ps also increases, the sealing conditions for fluid shutoff, that is,

[0059]

(Equation 2)

Does not have a significant effect.

Therefore, it is not necessary to change the minimum value δmin [formula (1)] of the gap δ set in accordance with the size of the fine particle diameter φd of the powder fluid even if the rotational speed changes.
Even if it is preferable to change it, a small amount is sufficient. By focusing on this point, the following effects can be obtained.

During the application and immediately after the end of the application, by driving at a high rotational speed, a large pumping action by the thrust dynamic pressure seal can be obtained. Therefore, at the end of the application, a sufficient effect that the fluid mass at the tip of the discharge nozzle is sucked into the nozzle can be obtained. As a result, dripping and stringing are eliminated.

After the coating is completed, the number of revolutions is greatly reduced. Even in this case, as described above, the fluid is shut off while the flow path from the pump chamber to the discharge nozzle remains in a non-contact state. Further, the pumping pressure of the thread groove pump and the thrust dynamic pressure seal decreases in proportion to the rotation speed. As a result, it is possible to suppress an increase in temperature due to the shear force of the fluid. Further, when handling a coating material in which it is not preferable to apply high pressure and shearing force, damage to the material can be reduced.

FIG. 4 shows the relationship between the flow rate and the pressure of the thread groove pump under the conditions of Table 1 using the rotation speed as a parameter.

In the figure, the graph (a) shows the relationship between the flow rate and the pressure of the discharge nozzle. For example, an intersection A between the characteristics of the thread groove pump at N = 200 rpm and (a) is the operating point of the thread groove pump. At this operating point, the pressure upstream of the discharge P = 0.52 MPa, the flow rate Q passing through the discharge nozzle = 2.9 mm ³ /
s is determined.

If the gap δ of the thrust dynamic pressure seal becomes small and the fluid is shut off (Q = 0), the operating point of the thread groove pump shifts from A to B. The pumping pressure Pr = 2.01 MPa (point B) of the thread groove pump at this time is the pressure to be sealed by the thrust dynamic pressure seal.

Further, when the rotation speed is reduced to N = 50 rpm, the pumping pressure to be sealed by the thrust dynamic pressure seal decreases to Pr = 0.49 MPa (point C).

FIG. 5 shows the relationship between the pressure of the thrust dynamic pressure seal and the gap under the conditions of Table 2 using the rotation speed as a parameter.

From this graph, it is found that the pumping pressure Pr = 2.01 MPa (point B) of the thread groove pump at N = 200 rpm is obtained as follows:
The gap of the thrust dynamic pressure seal required to cut off the flow rate is δ = 0.01 mm.

Similarly, the gap of the thrust dynamic pressure seal required to cut off the pumping pressure Pr = 0.49 MPa (point C) of the thread groove pump at N = 50 rpm is δ = 0.01.
mm. The same applies to other rotation speeds, and it can be seen that the gap required for sealing hardly changes even if the rotation speed is changed.

When the application fluid can be handled as a Newtonian fluid, even if the number of rotations is changed as described above, theoretically, the setting conditions of the gap for interrupting the flow need not be changed.

However, for example, in the case of a viscoelastic fluid whose viscosity depends on the shear rate, the change of the viscosity with respect to the change in the shear rate is not linear. is there.

At this time, an appropriate gap δ for interrupting the flow rate at each rotation speed N may be obtained in advance by an experiment. This “characteristic of δ with respect to N” may be programmed in a computer, and a controller for driving the giant magnetostrictive element may be controlled so that an optimum gap δ is automatically obtained at each rotation speed.

FIG. 6 shows a method of controlling the number of revolutions for maintaining the state of the meniscus (interface) between the fluid and the air at the tip of the discharge nozzle in an optimum state.

FIGS. 7A and 7B schematically show the state of the meniscus at the tip of the nozzle in the case where the rotation speed is kept constant in all the application steps (a) and in the case where the rotation speed is varied (b). Show.

In FIG. 6 to which the present invention is applied, after the intermittent application is completed at T = t1, the application is stopped for a while in the section of t1 <t <t2. During this time, the fluid mass at the tip of the discharge nozzle (50 in FIG. 7B) is sucked into the nozzle by the pumping effect Ps of the thrust dynamic pressure seal.

At t = t2, the rotation speed is reduced from N = 300 → 50 rpm,
N = 50 rpm is maintained in the section of t3 <t <t4.

During this time, the meniscus 51 of the fluid is inside the nozzle, but the pumping effect Ps of the thrust dynamic pressure seal
Is significantly reduced to a level that balances with the surface tension, so that no fluid is sucked into the nozzle beyond the initial state (t = t2).

However, as shown in FIG. 7 (a), when “the rotational speed is kept constant in all the application steps”, the thrust dynamic pressure seal is set in the standby section t2 <t <t5. The fluid is gradually sucked into the nozzle by the pumping effect Ps. When the distance Δl between the position of the fluid meniscus 62 and the tip of the nozzle increases, the ejection delay occurs with respect to the next application start command.

As described above, by applying the present invention, even in a process having a long standby time, coating can be started instantly without time delay.

In this embodiment, a giant magnetostrictive element is used for the axial driving means. However, in a pump handling a very small flow rate, the stroke of the gap δ for constituting the “non-contact seal” is at most several tens of microns. And the stroke limit of an electrostrictive element such as a giant magnetostrictive element or a piezo element does not matter.

When a high-viscosity fluid is discharged, a large discharge pressure is expected to be generated by the pumping action of the radial groove. In this case, since the first actuator 1 is required to have a large thrust against high fluid pressure, it is preferable to use an electromagnetic strain type actuator capable of easily producing a force of several hundred to several thousand N. Since the electromagnetic distortion element has a frequency response of several MHz or more, the main axis can be linearly moved with high response. Therefore, the discharge amount of the high-viscosity fluid can be controlled with high response and high accuracy.

When a giant magnetostrictive element is used as the axial driving means, the conductive brush can be omitted as compared with the case where a piezoelectric element is used, so that the load on the motor (rotating means) can be reduced and the overall structure is extremely simple. Therefore, the moment of inertia of the moving part can be minimized, and the diameter of the dispenser can be reduced.

In the embodiment, the dynamic pressure seal is of the thrust type, but may be of the radial type.

[0085]

According to the fluid rotating device using the present invention, the following effects can be obtained. 1. High-speed discharge shutoff and start can be performed. 2. 2. No troubles such as clogging of flow passages and changes in fluid characteristics due to powder compression damage. Further, the pump of the present invention can have the following features.

High-speed application of a high-viscosity fluid is possible.

It is possible to discharge an extremely small amount with high precision.

If the present invention is applied to, for example, a surface mount dispenser, a phosphor coating for a PDP or CRT display, or a sealant coating for a liquid crystal panel, the advantages thereof can be fully exhibited, and the effect is enormous.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a dispenser according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a discharge section of the embodiment.

3A is a graph showing a relationship between a pressure generated by a thrust dynamic pressure seal and a gap. FIG. 3B is a plan view showing a spiral groove groove.

FIG. 4 is a graph showing a relationship between a flow rate of a radial groove and a rotation speed.

FIG. 5 is a graph showing a relationship between a pressure generated by a thrust dynamic pressure seal and a gap.

FIG. 6 (a) is a diagram showing the displacement of the rotation speed with respect to time. FIG. 6 (b) is a diagram showing the displacement of the piston with respect to time.

FIG. 7 (a) is a model diagram in a case where the rotation speed is kept constant in all the coating processes. FIG.

FIG. 8 is a diagram showing a conventional air pulse method.

[Explanation of symbols]

 9 shaft 11 pump chamber 12 suction port 13 discharge port 15 means for rotating 1 electromagnetic distortion element

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yamauchi Dai 1006 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 72) Inventor Shuji Ohno 1006 Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. DC19 DC21 DC24 DC30 EA05 EA31 EA35 EA37 EA39 4F041 AA04 AA05 AB01 BA02 BA10 BA34

Claims (7)

[Claims] 1. An axial drive is controlled to increase a discharge port side end face of a shaft and an opposing surface thereof at the time of fluid application, and to reduce the gap at the time of fluid shutoff.
A fluid application method, wherein the number of revolutions is changed in any one of steps of application interruption and standby. 2. The fluid application method according to claim 1, wherein the number of revolutions during application standby is set smaller than the number of revolutions during application. 3. The setting of the gap between the end face on the discharge port side of the shaft and the opposing face thereof at the time of application interruption is changed in accordance with the set rotation speed at the time of application interruption. The fluid application method as described. 4. The method as claimed in claim 1, wherein said fluid pumping means has a characteristic that a generated pressure changes in proportion to a rotation speed. 5. A motor as means for relatively rotating a shaft and a housing for housing the shaft, axial driving means for providing an axial relative displacement between the shaft and the housing,
A fluid suction port and a fluid discharge port communicating the pump chamber formed by the shaft and the housing with the outside; a fluid pumping means for pumping the fluid flowing into the pump chamber to a discharge port side; In the fluid application device including the exit side end surface and the dynamic pressure seal formed on the opposite surface, the rotation speed of the motor is variable in accordance with the timing of each of the steps of application start, application, application interruption, and standby. A fluid application device, comprising: a controller for causing the fluid to be applied. 6. The fluid application device according to claim 5, wherein said axial driving means is an electromagnetic strain element. 7. An electrostrictive element having a movable end on the front side and another fixed end on the rear side, a housing for accommodating the electrostrictive element, and rotating the electrostrictive element relative to the housing. 6. The fluid application device according to claim 5, further comprising: means for freely and movably supporting in the axial direction; and means for imparting rotation to the electromagnetic strain element.