Coating apparatus – Program – cyclic – or time control
Reexamination Certificate
2002-02-15
2004-07-13
Pianalto, Bernard (Department: 1762)
Coating apparatus
Program, cyclic, or time control
C118S050000, C118S305000, C118S323000, C118S500000, C118S600000
Reexamination Certificate
active
06761769
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to apparatus and method for applying a viscous material. In particular, the present invention relates to apparatus and method for applying adhesive on an electric circuit substrate, such as circuit board bearing electronic components thereon.
FIG. 4
illustrates a conventional adhesive applicator (
100
) for applying adhesive onto the circuit substrate for holding components thereon. The applicator (
100
) has an application head (
110
) for applying adhesive on the circuit substrate, a robot (
130
) for moving the head (
110
), a substrate holder (
140
) for introducing the circuit substrate into an interior of the applicator and then holding the substrate, and a controller (
150
) for controlling overall operations of the applicator. The robot (
130
) moves the head (
110
) in the X-direction by means of a motor (
132
), and the holder (
140
) moves the circuit substrate in the Y-direction by means of another motor (
142
). As a result of relative movement between the head (
110
) in X-direction and the holder (
140
) in Y-direction perpendicular to the X-direction in a horizontal plane, the head (
110
) may apple adhesive on a predetermined area of the circuit substrate. The moving distance of the head (
110
) in X-direction and that of the holder (
140
) in Y-direction are controlled by the controller (
150
).
Referring to
FIG. 5
, there is shown the head (
110
). The head (
110
) is equipped with three sets of applying mechanisms or units (
111
) each of which squeezes out the adhesive with an aid of air pressure applied thereto. Each of the applying units (
111
) has a syringe (
113
) with a nozzle (
112
) for receiving the adhesive and then discharging a predetermined volume of the adhesive through the nozzle (
112
) with an aid of air pressure, an air-supply (
115
) for supplying compressed air to the syringe (
113
), and an elevator (
120
) for moving the syringe (
113
) up and down in the Z-direction shown in the drawing so as to apply the adhesive on a circuit substrate.
FIG. 6
shows several elements of the applying unit (
111
) in FIG.
5
. As can be seen from the drawing, the air-supply (
115
) has a passage (
116
) for supplying the compressed air to the syringe (
113
), and a valve (
117
) for regulating an amount of compressed air to be supplied. The elevator (
120
) has a hollow shaft (
121
) connected to the syringe (
113
) and allowing the compressed air to pass therethrough, a lever (
123
) rotatably mounted on a support shaft (
122
), a cam follower (
124
) rotatably fixed to the lever (
123
), and a cam (
125
) making an engagement with the cam follower (
124
). One end (
123
a
) of the lever (
123
) is connected to the elevation shaft (
121
), and the other end (
123
b
) thereof may contact with the drive shaft of a nozzle-selection cylinder (
126
). The lever (
123
) driven by the nozzle-selection cylinder (
126
) causes the cam follower (
124
) to engage with the cam (
125
). This causes that the one end (
123
a
) of the lever (
123
) rotates around the support shaft (
122
) in association with the rotation of the cam (
125
), moving the elevation shaft (
121
) up and down in Z-direction.
Referring to
FIGS. 4-6
, an operation of the applicator (
100
) so structured will be described in detail. The head (
110
) conducts a trial application of the adhesive (
102
) on a trial tape (
101
) before the application of adhesive onto a circuit substrate. As shown in
FIG. 6
, when the valve (
117
) of the air-supply (
115
) is opened for a predetermined period of time, the float (
114
) inside the syringe (
113
) is forced down due to the air pressure. This causes a predetermined volume of the adhesive (
102
) to be discharged from the syringe (
113
) through the tip end (
112
a
) of its nozzle (
112
). The cam follower (
124
) of the lever (
123
) comes into contact with the cam (
125
) by the actuation of the nozzle-selection cylinder (
126
). As mentioned above, the rotation of the cam (
125
) causes the one end (
123
a
) of the lever (
123
) to rotate, thereby the syringe (
113
) is moved down in the Z-direction via the elevation shaft (
121
). Then, the adhesive (
102
) discharged from the tip end (
112
a
) of the nozzle (
112
) is applied on the trial tape (
101
) opposing to the nozzle tip end (
112
a
). (see
FIG. 5
) After the application of the adhesive, the syringe (
113
) is moved up to the original position due to further rotation of the cam (
125
).
The condition of the applied adhesive (
102
) on the trial tape is imaged by a recognition camera (
118
) mounted on the head (
110
) (see FIG.
5
). The controller (
150
) measures the area of She adhesive applied on the trial tape based on the output from the recognition camera (
118
), and determines whether the measured area meets a predetermined and intended diameter of the adhesive to be applied. The trial application of the adhesive followed by the image-pickup operation is repeated until the measured diameter of the applied adhesive on the trial tape falls within the allowable range of the intended diameter. After the diameter of the adhesive applied on the trial tape has come within the allowable intended diameter range, a circuit substrate is introduced into the apparatus and then firmly held by the holder (
140
). Then, the operation of applying the adhesive (
102
) onto the circuit substrate is started.
The prior-art applicator (
100
) has several drawbacks. For example, the volume of the discharged adhesive (
102
) varies depending on remaining amount of the adhesive (
102
) in the syringe (
113
), since the adhesive (
102
) in the syringe (
113
) is forced out by means of air pressure. U.S. Pat. No. 5,564,606 and JP (A)-276963/1999 disclose certain techniques for solving the problem of volume fluctuations of discharged viscous materials or adhesive.
Referring to
FIGS. 7 and 8
, the application mechanism (
1
) disclosed in JP (A)-276963/1999 mainly has an adhesive-applying member (
4
) equipped with a nozzle (
3
) for discharging adhesive (
2
), a discharge shaft (
5
) rotatably inserted in the hollow interior of the adhesive-applying member (
4
) and extending in the longitudinal direction along the axis of the nozzle (
3
), a driving device (
6
) for is rotating the discharge shaft (
5
) around its axis, and an adhesive supply unit (
8
) for supplying the adhesive (
2
) to the adhesive-applying member (
4
). A portion of the mechanism (
1
) surrounded by a circle indicated by alphabet I is illustrated in
9
in detail. As shown in the drawing, a screw-like portion (
11
) is formed at one end of the discharge shaft (
5
) close to the nozzle (
3
) (lower side of the drawing). Connected to the other end (
5
a
) of the discharge shaft (
5
) (upper side of the drawing) is a transmission shaft (
13
) mounted for sliding along the axial direction relative to a connecting shaft (
12
) and for transmitting a rotation of the connecting shaft (
12
) to the discharge shaft (
5
). As shown in
FIG. 7
, an output shaft (
7
) of the driving device (
6
) is connected to the other end of the connecting shaft (
12
) via a coupling (
14
). Thus, when the driving device (
6
) is operated, the discharge shaft (
5
) is caused to rotate around its axis via the output shaft (
7
), the coupling (
14
), the connecting shaft (
12
) and the slidable transmission shaft (
13
).
With reference to
FIG. 9
, a passage (
16
) for supplying the adhesive is formed in the adhesive-applying member (
4
) at a position corresponding to the upper end (
11
a
) of the screw-like portion (
11
). The passage (
16
) is communicated with a flexible adhesive-supplying tube (
18
) via a fixture (
17
). The flexible adhesive-supplying tube (
18
) is connected to the syringe (
9
) of the adhesive supply unit (
8
) (see
FIG. 7
) through which the adhesive (
2
) accumulated in the syringe (
9
) is supplied. When the discharge shaft (
5
) is rotated around its axis, the adhesive (
2
) supplied to the upper end (
11
a
) of the screw-like portion (
11
) is forced toward the other
Chikahisa Naoichi
Hashimoto Shunji
Inaba Yuzuru
Terayama Eiichiro
Matsushita Electric - Industrial Co., Ltd.
Pianalto Bernard
Wenderoth , Lind & Ponack, L.L.P.
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