Apparatus and method for applying fluid

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus and a method for applying a fluid which can be used in a production process of electronic components, household electrical appliances, etc. for discharging a constant amount of various kinds of liquid such as adhesives, solder paste, phosphors, grease, paint, hot melt, medicines, foods, etc.

2. Description of the Related Art

While a liquid discharge apparatus (dispenser) has been conventionally used in a variety of fields, a technique of highly accurately and stably controlling to discharge a minute amount of fluid material becomes required in accordance with the current need for electronic components to be made compact with a high recording density. In the field of, for example, a surface mounting technique (SMT) for electronic components, high-speed, high-density, high-quality and automatic mounting into a micro-size is required and, the contents of the requirement to the dispenser are summarized as follows:

(1) To obtain a highly accurate application amount while holding the application amount for each time minute;

(2) To shorten a discharge time, i.e., to discharge, shut and start the discharge at high speeds; and

(3) To meet highly viscous fluids in powders.

In order to discharge a liquid of a minute flow rate, dispensers of an air pulse system, a groove type, and the like have been practically used heretofore.

Among the dispensers of the aforementioned types, the dispenser of the air pulse system as indicated in

FIG. 8

has been widely employed. The dispenser of this system supplies a constant amount of the air supplied from a constant pressure source

20

into a cylindrical container

10

in pulses, thereby discharging a constant amount of a liquid

25

,corresponding to an amount of a pressure rise in the container

10

through a nozzle

12

.

The dispenser of the air pulse system is poorly responsive when discharging the fluid

25

. Meanwhile, a screw type dispenser, such as a viscous pump, has also been put in practical use. The dispenser of this type generally adopts a structure wherein an object to which the liquid or the like is to be applied by the dispenser, and the dispenser are made relatively movable in X, Y and Z directions, so that the liquid can be applied linearly by moving the object to be applied and the dispenser relatively in either the X or the Y direction while discharging the liquid from the dispenser.

In the above-described conventional application method, as is apparent from

FIGS. 9C and 9D

, a discharge control signal for letting the dispenser carry out a discharge operation is set to rise and fall with the same timing as a timing of a rising edge and a falling edge of a movement control signal for moving the dispenser and the object to be applied in the X or Y direction. It takes a predetermined amount of time before a constant amount of the fluid is discharged after the discharge control signal is supplied in the above dispenser, as is shown in FIG.

9

D. Similarly, it takes a predetermined period of time before the fluid discharge is actually stopped after a signal instructing stopping the discharge is supplied. Therefore, an application state of the fluid from the dispenser to the object to be applied becomes one such as is represented in FIG.

9

A. Specifically, the application starts at an application start part

30

with the time delay from the rise of the discharge control signal, having an application amount gradually increased, whereas the fluid is turned to a mass shaped at a discharge termination part

32

because of the application amount being amassed by the time difference between the signal and the actual discharge stop. In other words, as indicated by a dotted line in

FIG. 9A

, it is difficult for the conventional fluid application apparatus to form a fixed fluid application region and obtain a uniform application amount over an entire range of the fluid application region. The reason for this is that starting and stopping the discharge of the fluid having fluidity is subject to a time lag, while moving the object to be applied and the dispenser in the X or Y direction is a mechanical operation without a time lag. Although, for example, an operation timer can be set to delay the movement in the X or Y direction, to stop the discharge earlier, etc. for solving the above problem and obtaining a normal application state, it is difficult to match the fluid discharge with the mechanical operation particularly in the case of a fluid which is viscous, and consequently the application state still varies.

In the field of forming circuits which increasingly becomes highly accurate and superfine; and in the fields of manufacturing processes of forming electrodes and ribs of image tubes such as PDPs (plasma display panels), CRTs, etc., applying a sealing material of liquid crystal panels, and manufacturing optical discs or the like; the following requirements are made in relation to a fine application technique:

(1) To be able to quickly stop the application after continuous application and to immediately restart the continuous application a short time later. It is ideal to control a flow rate in the order of, for example, a 0.01 second; and

(2) To be able to meet fluids in powders, for example, without crushing and breaking the powder, clogging a channel, or the like trouble by mechanically shutting the channel.

SUMMARY OF THE INVENTION

An object of the present invention is therefore to provide an apparatus and a method for applying a fluid, while eliminating the above-described problems, whereby an application amount of the fluid to be applied can be kept stable even at a fluid discharge start part and a fluid discharge termination part.

In order to accomplish the above objective, the present invention has following constructions.

According to a first aspect of the present invention, a fluid application apparatus, which is provided with an application head including:

a cylindrical discharge member for carrying out a discharge operation for a fluid to be applied;

a storage member shaped like a recess for storing the discharge member via a first gap in a diametrical direction of the discharge member and a second gap in an axial direction of the discharge member, having a discharge passage extending along a center axis of the discharge member to be opened to the second gap for discharging the fluid supplied to the first gap and moved to the second gap to the outside;

a moving device having an electro-magnetostrictive element for controlling starting and stopping the discharge of the fluid through the discharge passage to the outside by moving the discharge member along the axial direction;

a rotating device for rotating the discharge member along a circumferential direction of the discharge member; and

a movement groove formed to at least either a circumferential face of the discharge member facing the first gap or a first opposite face opposite to the circumferential face of the storage member for moving the fluid present at the first gap to the second gap by the rotation of the discharge member by the rotating device, and

a control unit connected to the moving device and the rotating device for carrying out to the moving device an operational control of moving the discharge member in a discharge direction along the axial direction when the fluid is to be discharged through the discharge passage to the outside.

The control unit can also control the rotating device to rotate the discharge member when the fluid is to be discharged through the discharge passage to the outside.

The above control unit can further control the rotating device so as to stop the rotation of the discharge member, and at the same time, control the moving device so as to move the discharge member in a direction opposite to the discharge direction along the axial direction when the fluid discharge through the discharge passage is to be stopped.

The fluid application apparatus can be further provided with a supporting member for supporting an object to which the fluid is to be applied by the application head, a lift device for relatively moving the application head and the supporting member up and down, and a horizontal moving device for relatively moving the application head and the supporting member in a horizontal direction orthogonal to the lifting direction by the lift device. In a fluid application operation from the application head to the object to be applied, after the control unit makes the lift device relatively move the application head and the supporting member up and down to be close to each other, at a fluid discharge start time, the control unit executes operational controls to the rotating device and the moving device of starting the rotating the discharge member and the moving the discharge member in the discharge direction, and at the same time an operational control to the horizontal moving device of starting the relatively moving the application head and the supporting member in the horizontal direction; until the fluid discharge through the discharge passage is stopped after the discharge start, the control unit executes an operational control to the rotating device of the rotating the discharge member and an operational control to the horizontal moving device of the moving the application head and the supporting member; and at a stop time of the fluid discharge, the control unit executes an operational control to the rotating device of stopping the rotating the discharge member, an operational control to the moving device of stopping the moving the discharge member, and at the same time an operational control to the horizontal moving device of stopping the relatively moving the application head and the supporting member in the horizontal direction as well as an operational control to the lift device of relatively moving the application head and the supporting member up and down to separate from each other.

According to a second aspect of the present invention, there is provided a fluid application method carried out with the use of an application head which includes a cylindrical discharge member for carrying out a discharge operation for a fluid to be applied;

a storage member shaped like a recess for storing the discharge member via a first gap in a diametrical direction of the discharge member and a second gap in an axial direction of the discharge member, having a discharge passage extending along a center axis of the discharge member to be opened to the second gap for discharging the fluid supplied to the first gap and moved to the second gap to the outside;

a moving device having an electro-magnetostrictive element for controlling starting and stopping the discharge of the fluid through the discharge passage to the outside by moving the discharge member along the axial direction;

a rotating device for rotating the discharge member along a circumferential direction of the discharge member; and

a movement groove formed to at least either a circumferential face of the discharge member facing the first gap or a first opposite face opposite to the circumferential face of the storage member for moving the fluid present at the first gap to the second gap by the rotation of the discharge member by the rotating device,

the method comprising:

moving the discharge member in a discharge direction along the axial direction when the fluid is to be discharged through the discharge passage to the outside.

In the above-described fluid application method of the second aspect, the discharge member can be rotated, and moreover moved in the discharge direction when the fluid is to be discharged through the discharge passage to the outside, while the rotation of the discharge member is stopped and the discharge member can also be moved in a direction opposite to the discharge direction along the axial direction when the fluid discharge from the discharge passage is to be stopped.

Further, the fluid application method of the second aspect enables an operation control, whereby, when application from the application head to an object to which the fluid is to be applied by the application head is to be carried out, after the application head and the object to be applied are relatively moved to be close to each other, at a fluid discharge start time, the rotation of the discharge member and the movement of the discharge member in the discharge direction are started, and at the same time, the application head and the object to be applied are started to be relatively moved in a horizontal direction; before a stop of the fluid discharge through the discharge passage after the discharge start, the rotating the discharge member and, the moving the application head and the supporting member are carried out; and at a stop time of the fluid discharge, the rotating the discharge member is stopped, the moving the discharge member is stopped, and at the same time an operational control of stopping the relative movement of the application head and the object to be applied in the horizontal direction as well as relatively moving the application head and the object to be applied up and down to separate from each other is carried out.

According to the fluid application apparatus of the first aspect and the fluid application method of the second aspect of the present invention, there are provided the application head and the control unit, so that the operation is controlled to move the discharge member in the discharge direction along the axial direction when the fluid is to be discharged. By adopting the above arrangement, the fluid application apparatus having the moving device including the electro-magnetostrictive element to the application head is enabled to control the fluid discharge, that is, temporarily increase a discharge amount of the fluid at a fluid discharge start part.

When the fluid is to be discharged, the control unit may control rotation of the discharge member and also move the discharge member in the discharge direction along the axial direction. This arrangement enables the fluid to be supplied to the discharge member through the rotation of the discharge member, thereby the fluid being able to be discharged more smoothly.

When the discharge is to be stopped, the control unit controls to stop the rotation of the discharge member and move the discharge member in the opposite direction to the discharge direction. Because of the above arrangement, it becomes possible to temporarily increase the discharge amount of the fluid at the fluid discharge start part, and suppress the fluid so as not become stringy and prevent an application amount from increasing at a fluid discharge end part. The application amount of the fluid can be stabilized both at the fluid discharge start part and the fluid discharge end part.

There are also provided the lift device and the horizontal moving device, thereby moving the object to be applied in the horizontal direction in correspondence to the fluid discharge start operation and the fluid discharge termination operation by the discharge member. The application amount of the fluid to be applied to the object to be applied is accordingly stabilized even at the fluid discharge start part and the fluid discharge end part.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention will become clear from the following description taken in conjunction with the preferred embodiment thereof with reference to the accompanying drawings in which:

FIG. 1

is a diagram showing a configuration of a fluid application apparatus according to an embodiment of the present invention;

FIG. 2

is an enlarged view of a discharge member part of an application head shown in

FIG. 1

;

FIGS. 3A

,

3

B,

3

C and

3

D are diagrams showing a relation between a state of a fluid applied by the fluid application apparatus in FIG.

1

and the operation of each part in the fluid application apparatus;

FIG. 4

is a diagram showing a terminal state of an application operation for the fluid;

FIG. 5

is a diagram showing a state successive to the state of

FIG. 4

when an application nozzle moves up in the related art;

FIG. 6

is a diagram showing a state successive to the state of

FIG. 4

when the application head shown in

FIG. 1

moves up;

FIG. 7

is a diagram explanatory of a method of judging whether an application state of the fluid is good or not in experiments with the use of a conventional application apparatus and the fluid application apparatus shown in

FIG. 1

;

FIG. 8

is a diagram of the conventional application apparatus; and

FIGS. 9A

,

9

B,

9

C and

9

D are diagrams showing a relation between a state of a fluid applied by the conventional application apparatus and the operation of each part of the application apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A fluid application apparatus and a fluid application method carried out by the fluid application apparatus which are embodiments of the present invention will be described below with reference to the attached drawings throughout which like parts are designated by like reference numerals. The fluid application apparatus of the present invention is exemplified as is used in a field of mounting electronic components on circuit formation objects. Therefore, a fluid to be applied by the apparatus is a material for fixing, that is, a generally named adhesive for fixing electronic components to substrates, connecting electrodes of electronic components to electrodes of substrates, connecting wired substrates with each other, connecting wired substrates to LCDs, etc. However, the fluid application apparatus is not limited to the above mounting field and the above fluid, and is applicable, e.g., to various kinds of fluid in the fields of medicines, foods and the like.

FIG. 1

shows a fluid application apparatus

300

constructed in accordance with the preferred embodiment of the present invention. The fluid application apparatus

300

comprises an application head

100

for discharging a fluid, and a control unit

180

. The apparatus can also comprise a lifting device

311

, a supporting member

312

for an object on which the fluid is to be applied, and a horizontal moving device

313

.

The application head

100

will be described in the first place. The application head

100

can have, as essential parts constituting the application head, a cylindrical discharge member

108

, a storage member

113

in which the discharge member

108

is stored via a gap and to which a discharge passage for discharging the fluid to be applied is formed, a moving device

101

for moving the discharge member

108

in its axial direction, a rotating device

118

for rotating the discharge member

108

in its circumferential direction, and a movement groove

134

formed to a circumferential face of the discharge member

108

as shown in FIG.

2

.

As is clear from

FIG. 1

, the application head

100

, which roughly includes the above-described parts, has a construction in which the rotating device

118

, a housing

112

of the moving device

101

and the storage member

113

are arranged coaxially in this order. In the application head

100

, the fluid to be applied is supplied into the gap formed by the storage member

113

and the discharge member

108

, and is controlled so as to be discharged by the rotation of the discharge member

108

by the rotating device

118

and by the movement of the discharge member

108

in the axial direction by the moving device

101

, so that an application amount of the fluid is stabilized even at the start of fluid discharge and at the end of the fluid discharge. The structure and the operation of the application head

100

will be fully described below.

First, the moving device

101

will be described. In order to quickly and intermittently supply a fluid having a high viscosity in a minute amount and with a high degree of accuracy, according to the present embodiment, the moving device

101

uses as a driving source, a super magnetostriction rod

105

with a super magnetostrictive element which can obtain a high positioning accuracy for a member to be moved, has a high responsiveness, and can generate a large load. The super magnetostrictive element is used as an example functioning as electro-magnetostrictive elements in the embodiment.

The moving device

101

includes a rear side yoke

103

, a rear side permanent magnet

104

, the super magnetostriction rod

105

, a front side permanent magnet

106

, a front side yoke

107

, a magnetic field coil

120

, a yoke material

121

and the housing

112

. More specifically, as indicated in

FIG. 1

, the loop-shaped magnetic field coil

120

is mounted to the yoke material

121

attached to an inner wall of the housing

112

inside the hollow housing

112

, and the loop-shaped super magnetostriction rod

105

is arranged so as to penetrate a central part of the magnetic field coil

120

in a non-contact state relative to the magnetic field coil

120

. By this arrangement, the magnetic field coil

120

can generate a magnetic field to act on the super magnetostriction rod

105

in a direction in which the super magnetostriction rod

105

extends. Therefore, an extension/contraction of the super magnetostriction rod

105

can be controlled in a non-contact state from the outside by controlling the magnetic field generated by the magnetic field coil

120

, in other words, by controlling a current to be supplied from a current supply device

166

to the magnetic field coil

120

by the control unit

180

. The super magnetostrictive element constituting the super magnetostriction rod

105

is formed of an alloy of a rare earth element and iron. For example, BFe

2

, DyFe

2

, SmFe

2

or the like is known as the alloy.

The loop-shaped rear side permanent magnet

104

and front side permanent magnet

106

are arranged on both ends of the super magnetostriction rod

105

, and furthermore, the rear side yoke

103

is disposed adjacent to the rear side permanent magnet

104

. The front side yoke

107

is disposed adjacent to the front side permanent magnet

106

. The rear side permanent magnet

104

and the front side permanent magnet

106

generate a magnetic field preliminary to the super magnetostriction rod

105

, thereby raising a working point of the magnetic field. A super magnetostriction linearity to an intensity of the magnetic field can be improved by this magnetic bias. The permanent magnets

104

and

106

are not essential and may be eliminated from the arrangement. At the same time, the magnets

104

and

106

are not limited to permanent magnets and can be anything that functions as a source for generating a magnetic force.

In the above-constituted moving device

101

, there is formed a closed loop magnetic circuit for controlling the extension/contraction of the super magnetostriction rod

105

by the magnetic field acting, e.g., in a direction of the super magnetostriction rod

105

→the rear side permanent magnet

104

→the rear side yoke

103

→the yoke material

121

→the front side yoke

107

→the front side permanent magnet

106

→the super magnetostriction rod

105

. The magnetic field can be made opposite in direction to the above in some cases.

More specifically, because of the rear side yoke

103

, rear side permanent magnet

104

, super magnetostriction rod

105

, front side permanent magnet

106

, front side yoke

107

, magnetic field

120

and yoke material

121

, the moving device

101

is constituted as a super magnetostriction actuator which can control the extension/contraction of the super magnetostriction rod

105

in the extension direction of the super magnetostriction rod

105

, namely, an axial direction

171

of the application head

100

by the current supplied to the magnetic field coil

120

. The front side yoke

107

extends/contracts in the axial direction

171

as well when the super magnetostriction rod

105

extends/contracts in the axial direction

171

.

The rotating device

118

is secured with bolts

124

to the rear side of the housing

112

. The rotating device

118

using a motor in the embodiment is controlled in the operation by the control unit

180

. The rotating device

118

has an output shaft

118

a

, which is coupled via a coupling

119

to one end part of the rear side yoke

103

. The coupling

119

transmits a rotational force of the output shaft

118

a

in a circumferential direction

172

to the rear side yoke

103

, and moreover holds the rear side yoke

103

movably in the axial direction

171

. To the one end side of the rear side yoke

103

is fitted a rear side sleeve

122

slidably in the axial direction

171

and in the arrow direction

172

to the rear side yoke

103

. Therefore, the rear side yoke

103

can be rotated inside the housing

112

, e.g., in the circumferential direction indicated by the arrow

172

by the rotating device

118

, and is supported via the rear side sleeve

122

and a bearing

123

rotatably relative to the housing

112

.

The application head

100

further comprises a center shaft

109

which projects from the rear side yoke

103

and extends at the center of the application head

100

along the axial direction

171

. The center shaft

109

uses a non-magnetic material in order that it not affect the magnetic circuit of the moving device

101

. Since the rear side yoke

103

is rotated by the rotating device

118

as described above, the center shaft

109

can similarly rotate about its axis, i.e., in the direction indicated by the arrow

172

. The center shaft

109

is fitted slidably in the axial direction

171

and rotatably in the circumferential direction

172

to each of the loop-shaped rear side permanent magnet

104

, super magnetostriction rod

105

and front side permanent magnet

106

.

The center shaft

109

extends to one end part of the front side yoke

107

and is coupled to the front side yoke

107

by a pin

110

. Therefore, the front side yoke

107

rotates integrally with the center shaft

109

in the same direction. The front side yoke

107

, having a front side sleeve

125

fitted thereto, is supported via a bearing

126

rotatably to the housing

112

.

The above pin

110

may be a key. The above bearing

126

may be a normal bearing, or a guide member capable of rotating and moving in an axial direction.

There are bias springs

127

and

128

arranged as an example of an urging force generation member between the rear side yoke

103

and the rear side sleeve

122

, and between the front side yoke

107

and the front side sleeve

125

, respectively. It may be possible under a specific condition to set either one of the springs

127

and

128

. These springs

127

and

128

generate a load of pressing the super magnetostriction rod

105

by the rear side yoke

103

and the front side yoke

107

via the rear side permanent magnet

104

and the front side permanent magnet

106

. As a result, a compressive stress is applied in the axial direction

171

at all times to the super magnetostriction rod

105

, thereby being able to eliminate demerit of the super magnetostrictive element subject to a tensile stress in the event that a repeated stress is generated by the extension/contraction of the super magnetostriction rod

105

in the axial direction

171

caused by the magnetic field coil

120

.

The rotational force by the rotating device

116

is transmitted only to the center shaft

109

and the front side yoke

107

by the the moving device

101

as above, without generating a torsional torque to the super magnetostrictive element which is a brittle material.

The discharge member

108

is mounted detachably to one end of the front side yoke

107

by bolts

161

as an example of the fastening member. The T-shaped discharge member

108

has a flange part

1081

attached to one end to be made a mounting part to the front side yoke

107

, and a projecting part

1082

integrally molded with the flange part

1081

to project from the flange part

1081

. The discharge member

108

is a member for carrying out a discharge operation for the fluid.

The movement groove

134

is formed spirally in a circumferential face

1082

a

of the projecting part

1082

, which will be described in detail later.

Since the front side yoke

107

is moved so as to extend/contract in the axial direction

171

by the moving device

101

, the discharge member

108

moves simultaneously with the front side yoke

107

in the same direction. Moreover, the discharge member

108

rotates in the circumferential direction

172

via the front side yoke

107

through the rotation of the center shaft

109

in the circumferential direction

172

by the rotating device

118

. The discharge member

108

can move in the axial direction

171

and in the circumferential direction

172

at the same time and independently of each other as above.

The storage member

113

, for storing or housing the discharge member

108

, has a main member

1131

, a nozzle member

1132

with a discharge nozzle

116

and a mounting member

1133

. As shown in

FIG. 2

, the main member

1131

has a recess

1134

for storing the projecting part

1082

of the discharge member

108

via a first gap

162

in a diametrical direction of the projecting part

1082

to a circumferential face

1082

a

of the projecting part

1082

and via a second gap

163

in the axial direction of the projecting part

1082

to a discharge end face

1083

of the projecting part

1082

. Moreover, the main member

1131

includes a fluid supply passage

115

for supplying the fluid

175

to the first gap

162

. The projecting part

1082

is movable in the axial direction

171

inside the recess

1134

. The main member

1131

is attached detachably to the housing

112

by bolts

164

as an example of the fastening member. The storage member

113

has a recess

1137

so as to form a space in which the flange part

1081

of the discharge member

108

is freely movable in the axial direction

171

inside the storage member

113

in a state with the storage member

113

attached to the housing

112

.

The nozzle member

1132

is a member secured by the mounting member

1133

detachably to an end part of the main member

1131

, and has an opposite face

131

for forming the second gap

163

with the discharge end face

1083

when the nozzle member

1132

is attached to the main member

1131

. The discharge nozzle

116

projects along the axial direction

171

from the nozzle member

1132

. Through the nozzle member

1132

and the discharge nozzle

116

is formed a discharge passage

1135

for discharging the fluid

175

to the outside after being supplied to the first gap

162

and moved to the second gap

163

by the discharge member

108

. The discharge passage

1135

, which extends along a center axis of the discharge member

108

, is opened to the second gap

163

.

Neither of the discharge end face

1083

and the opposite face

131

is provided with a structure for controlling the discharge operation of the fluid

175

, e.g., a structure formed spirally from the center part of the discharge member

108

to the circumference thereof, or the like.

The mounting member

1133

has a screw part

1136

to be engaged with the main member

1131

and clamps the nozzle member

1132

along with the main member

1131

. The mounting member

1133

is screwed at the screw part

1136

to the main member

1131

, and thus is detachably connected to the main member

1131

.

The fluid

175

is filled in the first gap

162

and the second gap

163

between the main member

1131

and the discharge member

108

. Thus an O-ring

150

is attached as a sealing material to the main member

1131

as shown in

FIG. 1

so as to prevent the fluid

175

from leaking to the front side yoke

107

through the first gap

162

. The first gap

162

and the second gap

163

function as a pump chamber for supplying the fluid

175

to the discharge passage

1135

.

The fluid supply device

165

for supplying the fluid is connected to the fluid supply passage

115

, which is controlled by the control unit

180

.

The movement groove

134

formed in the circumferential face

1082

a

of the projecting part

1082

will now be discussed.

As illustrated in

FIG. 2

, the movement groove

134

is a groove for moving the fluid present in the first gap

162

to the second gap

163

through the rotation of the discharge member

108

in the circumferential direction

172

is by the rotating device

118

. The groove

134

has a function similar to a function of a groove used in a spiral groove dynamic pressure bearing or a screw groove pump. The above movement of the fluid from the first gap

162

to the second gap

163

by the movement groove

134

generates a supply pressure to the fluid

175

. The supply pressure is determined by a rotational angular speed, a groove depth, a groove angle, a groove width, a ridge width, and the like of the movement groove

134

. According to the embodiment, for instance, 1-2 threads, a groove pitch of 0.5-4 mm, the groove depth of 0.01-1 mm and the groove width of 0.1-3 mm can be adopted. Single-thread, the groove pitch of 1.5 mm, the groove depth of 0.3 mm and the groove width of 1 mm are preferable as one example.

The movement groove

134

is formed in the circumferential face

1082

a

of the projecting part

1082

of the discharge member

108

in the embodiment. However, the position where to form the movement groove is not limited to this and the movement groove

134

may be formed at least in either the circumferential face

1082

a

facing the first gap

162

, or a first opposite face

1131

a

opposed to the circumferential face

1082

a

of the main member

1131

of the storage member

113

.

As described above, both the motion in the axial direction

171

by the moving device

101

, and the motion in the circumferential direction

172

by the rotating device

118

can be applied to the discharge member

108

by the control unit

180

concurrently and independently. Thus, when the fluid is to be discharged to the outside from the discharge passage

1135

, the discharge member

108

is rotated in a fluid discharge direction by the rotating device

118

and at the same time, the discharge member

108

is moved in a discharge direction

171

a

along the axial direction

171

by the moving device

101

. Also, when the discharge of the fluid from the discharge passage

1135

is to be stopped, the rotating device

118

is made to stop the rotation of the discharge member

108

, and moreover the discharge member

108

is moved in a direction

171

b

opposite to the discharge direction

171

a

along the axial direction

171

. The movement of the discharge member

108

in the opposite direction

171

b

returns the discharge member

108

in the opposite direction

171

b

to an original position from a position to which the discharge member

108

is moved in the discharge direction

171

a.

In the present embodiment as described hereinabove, the discharge member

108

is rotated in the fluid discharge direction and also moved in the discharge direction

171

a

when the fluid is to be discharged to the outside from the discharge passage

1135

. However, it is possible to discharge the fluid to the outside by an arrangement in which only the discharge member

108

is moved in the discharge direction

171

a

, and the rotation of the discharge member

108

in the fluid discharge direction acts to supply the fluid to the second gap

163

.

A displacement detection sensor

129

is installed in the housing

112

. The displacement detection sensor

129

is disposed opposite to the flange part

1081

of the discharge member

108

for detecting a displacement of the discharge member

108

in the axial direction

171

. The displacement detection sensor

129

is connected to the control unit

180

, and thus the control unit

180

obtains a displacement amount of the discharge member

108

. The displacement amount can be used as a movement amount of the discharge member

108

in the axial direction

171

at the discharge operation for the fluid, as will be described later, in order to control a discharge amount.

Since an input current applied to the super magnetostrictive element of the super magnetostriction rod

105

is proportional to a displacement at the super magnetostriction rod

105

, it is possible to control the positioning of the discharge member

108

in the axial direction

171

even with an open-loop control without installing the above displacement detection sensor

129

. However, in the case where the displacement detection sensor

129

is installed, thereby executing feedback control, characteristics of a hysteresis of the super magnetostrictive element can be improved, thus enabling more highly accurate positioning.

The lift device

311

will be described next. The lift device

311

in the embodiment moves the application head

100

up and down in the axial direction

171

along a vertical direction through the control of the control unit

180

.

The horizontal moving device

313

moves the supporting member

312

for supporting an object

320

to which the fluid is to be applied from the application head

100

, in a horizontal direction orthogonal to the axial direction

171

, namely, mutually orthogonal X and Y directions under the control of the control unit

180

.

Although the embodiment is constructed so as to move the application head

100

up and down and move the supporting member

312

horizontally, the embodiment is not restricted to this arrangement and may be constructed so that the application head

100

is moved horizontally while the supporting member

312

is moved up and down. In short, operations of the up/down movement and the horizontal movement may be carried out relative to the application head

100

and the supporting member

312

.

The control unit

180

will be described below. The control unit

180

controls the rotating device

118

, fluid supply device

165

, current supply device

166

, lift device

311

and horizontal moving device

313

, and also controls the discharge of the fluid on the basis of displacement information supplied from the displacement detection sensor

129

.

Hereinbelow will be discussed the control executed when the fluid is supplied from the application head

100

to the object

320

, which is supported on the supporting member

312

, by the rotating device

118

, fluid supply device

165

, current supply device

166

, lift device

311

and horizontal moving device

313

.

In applying the fluid, the control unit

180

drives the lift device

311

in order to lower the application head

100

approximately to a height where a leading end of the discharge nozzle

116

of the application head, i.e., a fluid discharge part is adjacent to the object

320

. Then, as described in the description of the application head

100

, the control unit

180

causes the rotating device

118

to start rotating the discharge member

108

in the circumferential direction

172

and also causes the moving device

101

to start moving the discharge member

108

in the discharge direction

171

a

as indicated in FIG.

3

C. The rotation and the movement of the discharge member

108

are started at the same time in the embodiment. A discharge end face

1083

of the discharge member

108

, which is disposed at an initial position

1084

(as shown in FIG.

2

), is brought to a discharge position

1085

shown in

FIG. 2

by the movement in the discharge direction

171

a.

By rotating the discharge member

108

in the circumferential direction

172

, the fluid

175

present in the first gap

162

is moved to the second gap

163

, and consequently a pressure of the fluid

175

in the second gap

163

is increased. The discharge member

108

is further moved in a direction along the axial direction

171

to approach the nozzle member

1132

, that is, from the initial position

1084

to the discharge position

1085

in the discharge direction

171

a

. Since the volume of the second gap

163

is decreased through these operations, the pressure of the fluid

175

present in the second gap

163

is temporarily further increased. As a result, a discharge amount of the fluid

175

from the discharge nozzle

116

can be temporarily increased. A state when the pressure is increased is represented by a numeral

331

in FIG.

3

B.

The amount of the temporary increase of the discharge amount of the fluid

175

is proportional to a movement amount of the discharge member

108

in the discharge direction

171

a

. In other words, the fluid

175

is not discharged by an amount exceeding the movement amount of the discharge member

108

in the discharge direction

171

a

. Therefore, the arrangement in which the fluid

175

is temporarily increased by moving the discharge member

108

in the discharge direction

171

a

as in the present embodiment enables the fluid

175

to be prevented from being discharged excessively.

In the meantime, the control unit

180

makes the horizontal moving device

313

start moving the supporting member

312

in the X- or Y-direction as shown in

FIG. 3D

simultaneously with the rotation and the movement operations of the discharge member

108

. The movement in the X- or Y-direction is one at least in either the X-direction, or the Y-direction.

Since the object

320

is moved simultaneously with the temporary increase in the discharge amount of the fluid

175

by the rotation and movement of the discharge member

108

, an application amount of the fluid

175

to be applied can be stabilized at the start of discharge

332

as shown in FIG.

3

D. More specifically, although the application actually starts with a time delay from the application start instruction at the application start

30

and the application amount is gradually increased as indicated in

FIG. 9A

in the related art, the application amount is increased at the start of fluid discharge

332

as mentioned hereinabove according to the present embodiment. Therefore, the application state is improved so as to be close to an ideal state indicated by a dotted line in FIG.

3

A.

Until the discharge of the fluid

175

from the discharge passage

1135

stops after the start of the discharge, the control unit

180

controls the rotating device

118

in order to rotate the discharge member

168

in the circumferential direction

172

, and at the same time, controls the horizontal moving device

313

in order to move the supporting member

312

as above. At this time, the control unit

180

controls the moving device

101

and the rotating device

118

so that the discharge member

108

is kept in the discharge position

1085

without being moved in the axial direction

171

and is rotated at a constant rotational speed in the circumferential direction

172

.

Accordingly, the pressure of the fluid

175

at the second gap

163

is made constant or nearly constant by the rotation of the discharge member

108

as represented by reference numeral

333

in FIG.

3

B. The fluid

175

is constantly or nearly constantly discharged from the discharge nozzle

1132

, that is, applied by a constant or nearly constant amount onto the object

320

as indicated by reference numeral

334

in FIG.

3

A.

At a discharge stop time, the control unit

180

makes the rotating device

118

stop rotating the discharge member

108

in the circumferential direction

172

, and makes the moving device

101

start moving the discharge member

108

in the opposite direction

171

b

to the discharge direction

171

a

along the axial direction

171

from the discharge position

1085

to the initial position

1084

. In the embodiment, the movement of the discharge member

108

is started in the opposite direction

171

b

after the rotation is stopped.

In consequence of the stop of rotation stop and the start of movement of the discharge member

108

, as indicated by a reference numeral

335

in

FIG. 3B

, the volume of the second gap

163

increases, thus the pressure of the fluid

175

present at the second gap

163

is temporarily decreased. As a result, the fluid

175

can be sucked into the discharge nozzle

116

. A fall denoted by a reference numeral

337

indicating an end of the discharge operation in

FIG. 3C

corresponds to a terminal end point of the movement of the discharge member

108

in the axial direction

171

by the moving device

101

. As is apparent from the change of the fluid pressure seen in FIG.

3

B and the above description, the stop of rotation the discharge member

108

is carried out at a time point before the fall

337

, for instance, at a time point

338

indicated by the dotted line in

FIGS. 3B and 3C

.

Further, simultaneously with stopping movement of the discharge member

108

in the opposite direction

171

b

, the control unit

180

makes the horizontal moving device

313

stop moving the supporting member

312

in the X- or Y-direction.

The application amount of the fluid

175

to be applied can be stabilized at a discharge end part

336

as shown in FIG.

3

A. In the related art, the application amount is increased at the discharge end part

32

as shown in

FIG. 9A

, and also in the present invention, the fluid

175

is possibly discharged even though slightly from the second gap

163

and the discharge passage

1135

if the discharge member

108

is simply stopped rotating in the circumferential direction

172

. According to the present embodiment in contrast to the above, a discharge pressure is instantaneously turned negative by moving the discharge member

108

in the opposite direction

171

b

, thus the fluid discharge can be instantaneously stopped. Consequently, the application state can be improved, so that the application state can be close to the ideal state indicated by the dotted line of FIG.

3

A.

As described above, at a time point when the application operation from the discharge nozzle

116

to the object

320

ends, the control unit

180

drives the lift device

311

in order to raise the application head

100

so that the discharge nozzle

116

and the object

320

are separated from each other.

At this time, the discharge member

108

can be moved in the opposite direction

171

b

before or simultaneously with the raising the application head

100

by the lift device

311

, thereby enabling the fluid

175

to be sucked into the discharge nozzle

116

. That is, the fluid

175

at the leading end of the discharge nozzle

116

can be prevented from becoming stringy, or the stringy state is reduced.

The operation in the above fluid application apparatus

300

, i.e., fluid application method carried out by the fluid application apparatus

300

will be described below. The fluid application method is executed while being controlled by the control unit

180

.

The horizontal moving device

313

is controlled to position the object

320

so that the discharge nozzle

116

of the application head

100

an application region on the object

320

supported by the supporting member

312

.

After the positioning, the lift device

311

lowers the application head

100

to bring the leading end of the discharge nozzle

116

close to the object

320

, for example, up to 0.05-0.5 mm from the object

320

. An operation for applying the fluid

175

is subsequently carried out on the object

320

. The application operation is already detailed in the foregoing description on the control unit

180

, and therefore will be described briefly here.

At a start time of the fluid discharge, the discharge member

108

is rotated by the rotating device

118

in the circumferential direction

172

and moved by the moving device

101

in the discharge direction

171

a

. This operation enables a large amount of the fluid

175

to be discharged temporarily from the leading end of the discharge nozzle

116

, as compared with the case in which the application is executed by driving only the rotating device

118

. Simultaneously with the start of the operation of the rotating device

118

and the moving device

101

, the horizontal moving device

313

is driven to move the object

320

so that the fluid is applied to the application region. By way of example, a rotation speed of the discharge member

108

by the rotating device

118

is set to 20-200 rpm, and a movement speed and a movement amount in the discharge direction

171

a

of the discharge member

108

by the moving device

101

are set to 2-20 mm/s and 3-30 mm respectively. A movement speed of the object

320

is set to 5-100 mm/s.

Until the fluid discharge ends after the start of the fluid discharge, the fluid is discharged and applied quantitatively by the rotation of the discharge member

108

by the rotating device

118

without driving the moving device

101

. The rotation speed of the discharge member

108

at this time is not changed from that at the start of the fluid discharge.

At the end time of the fluid discharge, the rotation of the discharge member

108

by the rotating device

118

is first stopped, and then the discharge member

108

is moved up in the opposite direction

171

b

by the moving device

101

from the discharge position

1085

to the initial position

1084

. The movement speed of the discharge member

108

in the opposite direction

171

b

is set to 2-20 mm/s by way of example.

The horizontal moving device

313

is stopped simultaneously when the discharge member

108

ends the upward movement. Since the fluid

175

is pulled into the discharge nozzle

116

because of the movement of the discharge member

108

in the opposite direction

171

b

at the end of the fluid discharge, the fluid is prevented from being extraordinarily applied at the end of the fluid discharge.

Simultaneously with the end of the fluid discharge or after the fluid discharge, the lift device

311

is driven to raise the application head

100

, when the application operation at one point of the object ends. Further, the discharge member

108

may be moved in the opposite direction

171

b

before or simultaneously with the upward movement of the application head

100

, thereby sucking the fluid

175

into the discharge nozzle

116

in order to prevent or reduce the above-mentioned stringy state.

At present, the fluid application apparatus

300

is preferably used to apply a sealing material for mounting components, etc., for example, an epoxy-based adhesive. Preferably, a viscosity of the adhesive is 10-500 Pas, the rotation speed of the discharge member

108

is 150-200 rpm and the movement speed of the object to be applied

320

is 10-30 mm/s.

The above-described operation is continued until the application to all application spots of the object

320

is completed. The object

320

is transferred to a next process when the fluid is applied to all spots completely, and a next object is carried into the fluid application apparatus

300

.

As is already described with reference to

FIG. 3A

, according to the fluid application apparatus

300

of the embodiment, the application amount of the fluid to be applied can be stabilized over the entire application region including the fluid discharge start part

332

and the fluid discharge end part

336

.

The above effect of stabilizing the application amount at the fluid discharge start part

332

and the fluid discharge end part

336

in the fluid application apparatus

300

according to the present embodiment will be described more specifically with reference to the result of experiments.

The experiment is carried out under conditions that an epoxy-based adhesive for sealing semiconductor elements is used as the fluid to be applied, which has a viscosity of 30 Pas while a standard value of the rotation speed of the discharge member

108

is 100 rpm, a standard value of the movement speed of the object

320

is 10 mm/s, and an application length is 30 mm. Under the above condition, as indicated in

FIG. 7

, with the fluid being discharged from the discharge head by the application head, the object

320

and the discharge nozzle are relatively moved from a movement start position

351

to a movement end position

352

. At this time, a difference between a start edge position of the fluid and the movement start position

351

at the fluid discharge start part

332

is measured as a start point size

353

, and moreover, a difference between a terminal edge position of the fluid and the movement end position

352

at the fluid discharge end part

336

is measured as an end point size

354

. The start point size

353

and the end point size

354

are marked with plus and minus symbols to indicate a deviation direction as in FIG.

7

. For example, when the start point size

353

at the movement start position

351

is plus, this means that the fluid discharge from the discharge nozzle is delayed with respect to the movement start of the discharge nozzle. On the other hand, when the start point size

353

at the movement start position

351

becomes minus, this means that the fluid is discharged from a time point of the movement start of the discharge nozzle.

The start point size

353

and the end point size

354

, and the application amount are measured seven times for each of the conventional application apparatuses and the fluid application apparatus

300

of the embodiment.

The experiment result is that the start point size

353

in the conventional application apparatus is plus 0.220 mm on average and its 3σ(σ: a standard deviation) is 0.347 mm, while the start point size

353

in the present application apparatus

300

is minus 0.132 mm on average and its 3σ is 0.172 mm. As is understood from the result, although the fluid cannot be discharged at the movement start time of the discharge nozzle in the conventional application apparatus, the fluid discharge is carried-out from the movement start time point of the discharge nozzle in the present application apparatus

300

. Additionally, the deviation of the fluid discharge in the fluid discharge of the application apparatus

300

is approximately half in comparison with the conventional apparatus, that is, the fluid discharge is made more stable as compared with the conventional apparatus.

The end point size is plus 0.329 mm on average and its 3σ is 0.080 mm in the conventional apparatus. On the other hand, the fluid application apparatus

300

of the embodiment has the end point size of plus 0.307 mm and its 3σ of 0.075 mm. With regards to the end point size, the fluid application apparatus

300

is not much different from the conventional apparatus. However, in terms of the 3σ in the application amount, the fluid application apparatus

300

of the present embodiment has 0.4 mg whereas the conventional apparatus has 1.2 mg. Therefore, an irregularity in the application amount of the fluid application apparatus

300

is restricted to ⅓ that of the conventional apparatus.

As described earlier, since the discharge member

108

is moved in the opposite direction

171

b

at the fluid discharge end time, the following effect is obtained when the application head

100

is moved up by the lift device

311

in the apparatus

300

.

If the application head

100

is simply moved upward without the discharge member

108

being moved in the opposite direction

171

b

at the fluid discharge end time as shown in

FIG. 4

, the fluid present at the leading end of the discharge nozzle

116

becomes stringy, extends to a length

341

and cuts at a thin part as illustrated in FIG.

5

. The fluid of an amount corresponding to the length

341

flows and adds to a fluid

340

applied below the fluid, resulting in an increase of the application amount at the discharge end part

32

as shown in FIG.

9

A.

According to the present invention, the discharge member

108

is moved in the opposite direction

171

b

immediately before the fluid discharge end or when the application head

100

is raised by the lift device

311

, so that the fluid

175

present at the leading end of the discharge nozzle

116

, can be drawn into the discharge nozzle

116

. Consequently, a stringy length

342

is made shorter than the length

341

as is clearly shown in

FIG. 6

, and the increase in the application amount of the fluid

175

at the discharge end part can be suppressed.

As is described hereinabove, according to the fluid application apparatus

300

of the embodiment, the application amount is stabilized by rotating the discharge member

108

in the circumferential direction

172

and moving the discharge member

108

in the axial direction

171

. Furthermore, the movement amount of the discharge member

108

in the axial direction

171

can be minutely controlled because the super magnetostrictive element is used as the driving source for the movement. The moving device

101

having the super magnetostrictive element can control the application amount precisely, and contributes to stabilize more the application amount in association with the effect of the controlled movement of the discharge member in the axial direction

171

.

Meanwhile, it may be considered possible to finely adjust a discharge timing so as to compensate for the discharge delay even in a system in which the fluid is discharged by air pressure or by the rotation of a screw. However, this type of adjustment is merely a time control without controlling the application amount. The conventional system cannot control both of the discharge timing and the application amount, having the application amount varied more as compared with the present embodiment.

Since the discharge member

108

is rotated in the circumferential direction

172

and moved in the axial direction

171

as above, it is possible to apply a high-visconty fluid at high speeds. Moreover, it becomes possible to discharge the fluid of a considerably minute amount highly accurately by finely controlling the movement amount of the discharge member in the axial direction

171

because the moving device

101

, which has the super magnetostrictive element as the driving source, is used to move the discharge member.

When the fluid application apparatus

300

of the present embodiment is employed for a dispenser in the surface mounting field, or used for applying a phosphor of PDPs and CRT displays, a sealing material of liquid crystal panels, etc., the advantage is fully exhibited and the effect becomes enormous.

In the above-described embodiment, the fluid is applied linearly as indicated in FIG.

3

A. That is, the horizontal moving device

313

is driven concurrently with the discharge operation of the discharge member

108

. However, an application form of the fluid is not limited to the shape shown in

FIG. 3A

, and the fluid can be applied point by point by separately carrying out the discharge operation by the discharge member

108

and the operation by the horizontal moving device

313

. The same effect as in the linear application can be obtained also in the point application.

Although the super magnetostrictive element is used as the moving device

101

in the above embodiment, the moving device is not restricted to the super magnetostrictive element and, for instance, the electro-magnetostrictive element such as a piezoelectric element or the like can be used because a stroke of the discharge member

108

in the axial direction

171

is several tens μm at most.

Permanent magnets

104

and

106

for bias are used at portions where the magnetic circuit is formed, which is particularly effective when the expansion and contraction of the electro-magnetostrictive element is used for both of the actions at expansion and contraction sides. However, the bias magnets may be eliminated if the expansion/contraction only at the expansion side is considered as more important.

The embodiment adopts the arrangement in which the fluid

175

is supplied to the second gap

163

by rotating the discharge member

108

with the movement groove

134

, and the rotating device

118

is provided with the motor therefor. In the case, e.g., without the movement groove

134

being formed, such an arrangement may be constituted wherein the fluid is discharged continuously with the utilization of a fluid supply source at the fluid supply device

165

, for example, with the use of air pressure.

Although the present invention has been fully described in connection with the preferred embodiment thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will be apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.

Number	Name	Date	Kind
5553742	Maruyama et al.	Sep 1996	A
5932012	Ishida et al.	Aug 1999	A

Number	Date	Country
2002-102768	Apr 2002	JP
2002-102770	Apr 2002	JP
2002-143745	May 2002	JP

Apparatus and method for applying fluid

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

Field of Search

US

International Classifications

Abstract

Description

Claims

Priority Claims (1)

US Referenced Citations (2)

Foreign Referenced Citations (3)