Handling: hand and hoist-line implements – Utilizing fluid pressure – Venturi effect
Reexamination Certificate
1999-10-13
2001-11-20
Kramer, Dean J. (Department: 2167)
Handling: hand and hoist-line implements
Utilizing fluid pressure
Venturi effect
C294S907000
Reexamination Certificate
active
06318777
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an IC suction mechanism and method, for sucking up an IC accommodated on a tray, and a horizontal conveyer type automatic handler incorporating the IC suction mechanism.
2. Description of Related Art
Explanation will be made of an IC suction mechanism according to an earlier development, with reference to
FIGS. 7
to
12
.
At first, the arrangement of a horizontal conveyer type automatic handler incorporating a suction mechanism (that is, a suction unit
2
in this example) for ICs.
Referring to
FIG. 7
which is a plan view illustrating the arrangement of the horizontal conveyer type automatic handler, there are shown a supply part
1
A, a preheat part
1
B, a measuring part
1
C, an accommodation part
1
D, a supply hand
1
E, an accommodation hand
1
F, a loader
1
G and an unloader
1
H.
The horizontal conveyer type automatic handler
1
conveys an IC by horizontally shifting an IC carrier (which is not shown).
The supply hand
1
E incorporates a plurality of supply suction units
2
(IC suction mechanisms) which will be explained later. The loader
1
G carries a tray thereon in which a plurality of ICs
5
to be tested are accommodated. The unloader
1
H carries thereon an empty tray.
Referring to
FIG. 8
, which is a perspective view illustrating a tray used in the loader
1
G and the unloader
1
H, a plurality of recesses
4
a
, e.g., in the example shown in
FIG. 8
, comprising a matrix of 4 lines and 5 rows, for accommodating the ICs
5
to be tested, are formed longitudinally and transversely on the tray
4
.
Referring to
FIG. 9
which is a perspective view illustrating an IC to be tested, an flat package IC
5
having a surface mounting shape is the object to be sorted by the horizontal conveyer type automatic handler.
Next, explanation will be made of the operation of the horizontal conveyer type automatic handler shown in FIG.
7
.
The trays
4
which carry thereon the ICs
5
which have not yet been tested, are shifted onto the loader
1
G by an operator. The supply hand
1
E successively shifts the ICs from the topmost one of the trays
4
on the loader
1
G onto the IC carrier located in the supply part
1
A.
The IC carrier in which the ICs
5
are accommodated by a predetermined number is shifted from the supply part
1
A to the preheat part
1
B. When the ICs
5
are heated up to a predetermined temperature in the preheat part
1
B, the IC carrier is shifted into the measuring part
1
C.
After the ICs
5
are tested in the measuring part
1
C, the IC carrier is shifted into the accommodation part
1
D. The ICs
5
are sorted and shifted into a tray
4
on the unloader
1
H by means of the accommodation hand
1
F. The IC carrier which is emptied in the accommodation part
1
F is returned to the supply part
1
A.
Thus, the IC carrier is circulated in the automatic handler
1
through the supply part
1
A, the preheat part
1
B, the measuring part
1
C, the accommodation part
1
D and the supply part
1
A in the mentioned order.
Next, an explanation will be made of an earlier developed IC suction mechanism (suction unit) with reference to
FIGS. 10A and 10B
.
Referring to
FIGS. 10A and 10B
which shows a suction unit as an example of the conventional IC suction mechanism, and in which
FIG. 10A
is a front view and
FIG. 10B
is a vertical sectional view, there are shown a suction unit
2
, a suction pad
2
A, a shaft
2
B, a compression coil spring
2
C, a direct acting bearing
2
D, a holder
2
E and a guide
2
F.
In
FIGS. 10A and 10B
, the hollow conical shape suction pad
2
A formed of elastic material such as rubber, is attached to the lower end part of the hollow shaft
2
B. The cylindrical guide
2
F is attached to the shaft
2
B so as to cover the suction pad
2
A. It is noted that with the provision of the guide
2
F, there has been proved that the capability of suction can be enhanced.
The shank part of the shaft
2
B is slidably held by the direct acting bearing
2
D enclosed in the holder
2
E. The compression spring
2
C wound on the shank part of the shaft
2
B is located between the guide
2
F and the holder
2
E so as to apply a force for separating the guide
2
F and the holder
2
E from each other. The shaft
2
B is formed at its upper end part with a flange for limiting the motion of the shaft
2
B.
The shaft
2
B is attached thereon with a tube communicated with the hollow part thereof and having a distal end connected with a vacuum pump (suction means). That is, when the vacuum pump sucks up the air in such a condition that the suction pad
2
A is made into contact with the IC
5
, the IC
5
is sucked up by the suction pad
2
A.
Referring to
FIGS. 10A and 10B
, the suction unit
2
has such a structure that when the holder
2
E is lowered so as to allow the suction pad
2
A to make contact with the IC, and the suction pad
2
A incorporating the suction unit
2
A slides so as to absorb unevenness of thickness of packages of the ICs without application of excessive stress to the ICs
5
.
Referring to
FIG. 11
which shows such a condition that the ICs
5
accommodated on the tray
4
are sucked, the IC pad
2
A is made into contact with the IC
5
and a gap C is defined between the upper surface of the holder
2
E and the flange of the shaft
2
B. In this condition, the IC
5
is sucked up as mentioned above.
FIG. 12
shows such a condition that no IC are accommodated on the tray
4
. In
FIG. 12
, the holder
2
E descends to the same position as that of FIG.
11
. In this figure, because there are no IC
5
on the tray
4
, the IC pad
2
A is brought into contact with the bottom surface of the tray
4
.
In the above-mentioned condition shown in
FIG. 12
, the horizontal conveyer type automatic handler
1
determines that the IC is sucked up, and accordingly, it tries to convey the tray
4
into the supply part
1
A in this condition. However, the tray
4
is extremely heavy in comparison with the IC
5
, the supply hand
1
E cannot convey the tray
4
so that the suction is released. In this case, the horizontal conveyer type handler
1
determines that it drops the IC
5
so as to stop the operation at that time, indicating dropping of the IC
5
.
The above-mentioned indication does mean that the suck-up of the IC is inferior. That is, it is erroneously recognized and determined that the supply hand
1
E drops the IC
5
during shifting.
SUMMARY OF THE INVENTION
The present invention was developed in order to solve the problems as mentioned above.
An object of the present invention is to provide an IC suction mechanism which can eliminate a defect such as erroneous recognition caused by such a matter that the tray is sucked up by the suction pad, and which can detect the presence of an IC on the tray.
Another object of the present invention is enhance the operational availability of a horizontal conveyer type automatic handler by applying the above-mentioned IC suction mechanism.
That is, in accordance with a first aspect of the present invention, the suction mechanism for an IC, in which a hollow shaft incorporating a suction pad at its lower end part, is supported by a holder so as to be vertically slidable, and the suction pad is made into resilient contact with an IC accommodated in a recess on a tray when the holder is lowered: wherein a stopper formed therein with a step part projected downward so as to laterally cover the suction pad is attached to the lower end part of the hollow shaft; the lower end of the step part is located above an IC contact surface of the suction pad, the lower surface of the stopper has at least a width with which the stopper is prevented from sinking into the recess on the tray, and a distance between the lower surface of the stopper to the IC contact surface of the suction pad is shorter than the depth of the recess on the tray.
According to the suction mechanism, because the stopper formed therein with a step part projected downward so as to laterally cover the suction pad is attached to the lower end part of the ho
Okamoto Kazumi
Tanaka Hideyuki
Ando Electric Co. Ltd.
Kramer Dean J.
Oliff & Berridg,e PLC
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