Conveyors: power-driven – With means to facilitate working – treating – or inspecting... – Condition responsive control of conveyor or station apparatus
Reexamination Certificate
1998-11-30
2001-02-20
Hess, Douglas (Department: 3652)
Conveyors: power-driven
With means to facilitate working, treating, or inspecting...
Condition responsive control of conveyor or station apparatus
C198S345100, C198S464100
Reexamination Certificate
active
06189674
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus and a method for transferring printed circuit boards.
BACKGROUND ART
Electronic components have become diversified in recent years, entailing the need for high-speed and highly accurate mounting of electronic components on printed circuit boards. Therefore, for high-speed and highly accurate mounting of electronic components on printed circuit boards, it is necessary to transfer and place printed circuit boards in prescribed positions quickly and with high accuracy.
Conventional apparatuses for transferring and positioning printed circuit boards in prescribed positions include what is shown in FIG.
4
. This transfer apparatus
20
comprises such driving units as transfer rails
22
, on which a printed circuit board
21
is to be transferred and guided; a vertically movable hook
23
disposed beside one of the transfer rails
22
; a mechanism
24
for moving the hook
23
up and down; a guide rail
25
for guiding the hook
23
back and forth in parallel with the transfer rails
22
; and a cylinder unit
26
for moving the hook
23
back and forth along the guide rail
25
. The hook
23
is engaged in an engaging hole
27
formed in the printed circuit board
21
, and the driving units are driven to move the hook
23
along the guide rail
25
to transfer and place the printed circuit board
21
in a prescribed position.
However, the above-described conventional transfer apparatus
20
requires, separately from the transfer rails
22
, driving units for moving the hook
23
in parallel with the transfer rails
22
; the mechanism
24
for moving the hook
23
up and down; and the guide rail
25
for moving the hook
23
back and forth in parallel with the transfer rail
22
, resulting in a greater size and complexity of the whole apparatus. This leads to problems regarding costs and installation space, and the printed circuit board
21
itself requires the engaging hole
27
for engaging the hook
23
, which limits the range of usable printed circuit boards
21
.
In this connection, there is also available, as shown in
FIG. 5
, a transfer apparatus provided with a conveyor belt
30
for guiding and transferring a printed circuit board
21
seated thereon is disposed on a frame
31
via a belt-driving unit
32
, and a stopper
33
for placing the printed circuit board
21
in a prescribed position, whereby the printed circuit board
21
is seated on the conveyor belt
30
and transferred to the stopper
33
by running the belt-driving unit
32
.
This transfer apparatus
20
can transfer the printed circuit board
21
in a simple configuration, but, if the conveyor belt
30
is run too fast when it transfers the printed circuit board
21
, the printed circuit board
21
may fail to be positioned exactly where it should be or electronic components mounted thereon may be dislocated or damaged by any impact that may occur when the printed circuit board
21
hits the stopper
33
even if it comes into contact with the stopper
33
in the prescribed position.
In order to solve the above-mentioned disadvantages, another apparatus is available, which effects control to lower the transfer speed of the conveyor belt
30
before the printed circuit board
21
hits the stopper
33
.
This can ease the impact of the printed circuit board
21
hitting the stopper
33
and also restrain the dislocation of, or the occurrence of defects in, the electronic components. However, because the printed circuit board
21
and the conveyor belt
30
are in frictional contact with each other, if a slip occurs between the printed circuit board
21
and the conveyor belt
30
, the printed circuit board
21
cannot slow down to the level of the lowered speed of the conveyor belt
30
, with the possible result that the printed circuit board
21
hits the stopper
33
with an unnecessarily great impact or, conversely, the printed circuit board
21
may be transferred at a lower speed than the conveyor belt
30
, taking too long a transfer time. Either trouble makes it difficult to realize high-speed transfers of the printed circuit board
21
.
DISCLOSURE OF THE INVENTION
An object of the present invention, therefore, is to provide an apparatus and a method for transferring printed circuit boards capable of obviating the above-described disadvantages.
As a means to solve the problems according to the present invention, the apparatus is provided with conveyor belts for seating a printed circuit board thereon; driving units for running the conveyor belts; a stopper for placing the printed circuit board in an intended position; a positioning detector for detecting the printed circuit board having hit the stopper; an arrival detector for detecting the printed circuit board having arrived in a prescribed position before the intended position where the printed circuit board ends its transfer; and a control unit for controlling the driving by the driving units in accordance with detection signal from the positioning detector and the arrival detector. This control unit has a function to output a slowdown signal to the driving units according to a detection signal from the arrival detector; a function to effect a delay by a prescribed period of time to stand by for a detection signal from the positioning detector, when a detection signal from the positioning detector and drive-stop signals from the driving units are output after a lapse of a standby period following the output of the slowdown signal; a function to determine that the printed circuit board has been placed in the intended position according to the detection signal output after the delay by the prescribed period of time; a function to supply a low-speed signal to the driving units to drive the conveyor belts at a low speed when no detection signal is output after the delay by the prescribed period of time; and a function to determine that the printed circuit board has been placed in the intended position by outputting a drive-stop signal to the driving units in accordance with a detection signal from the positioning detector after this low-speed signal is output.
According to this configuration, the transfer speed of the conveyor belts begins to be slowed down when the printed circuit board has arrived in the prescribed position before the intended position and, if the printed circuit board does not hit the stopper by the time the conveyor belts stop after their transfer speed begins to slow down, the conveyor belts are again driven to run at a slow speed until the printed circuit board hits the stopper so that the printed circuit board can be transferred to the intended position quickly and reliably.
The apparatus may also be provided with conveyor belts for seating a printed circuit board thereon; driving units for driving the conveyor belts; a stopper for placing the printed circuit board in an intended position; a positioning detector for detecting the printed circuit board having hit the stopper; an arrival detector for detecting the printed circuit board having arrived in a prescribed position before the intended position where the printed circuit board ends its transfer; and a control unit for controlling the driving of the driving units in accordance with detection signals from the positioning detector and the arrival detector, wherein the control unit has a function to supply a slowdown signal to the driving units according to a detection signal from the arrival detector; a function to supply a low-speed signal to the driving units to drive the conveyor belts at a low speed when no detection signal is output from the positioning detector and drive-stop signal are output from the driving units after a lapse of a standby period of time following the output of the slowdown signal; and a function to determine that the printed circuit board has been placed in the intended position by outputting a drive-stop signal to the driving units in accordance with a detection signal from the positioning detector after the low-speed signal is output.
According to this configuration, the transfer
Izumida Keizo
Nagae Kazuo
Yamamoto Hiroki
Hess Douglas
Matsushita Electric - Industrial Co., Ltd.
Parkhurst & Wendel L.L.P.
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