Apparatus for loading and unloading circuit boards along a conveyor system

A dedicated elevator having a "smart" handler mounted thereon to move circuit boards and the like from an assembly line to a storage magazine and back, providing a greatly reduced footprint over apparatus which must move and elevate entire magazines and which must accommodate magazines of various sizes. The smart handler both inserts boards into the magazine and retrieves the boards from the magazine. The smart handler includes a photosensitive gripper/pusher which can detect the edge of a board and grip the board by the detected edge to retrieve it from a slot in a storage assembly. The handler includes an actuator for moving the gripper along the direction of movement of the board for a predetermined distance to detect and engage boards which are irregularly stacked in a storage apparatus. The handler further includes a edge type conveyor which delivers boards to the gripper for full insertion into the storage assembly and receives boards from the gripper for delivery to the assembly line. A plurality of sensors and control elements monitor the position of the board and the components to accurately position the cooperative elements.

FIELD OF THE INVENTION 
The present invention relates to the field of automatic handling apparatus 
and more particularly to apparatus dedicated to the handling of printed 
circuit boards. In even greater particularity the present invention 
relates to apparatus for loading and unloading a plurality of circuit 
boards in a magazine for storage or transport during the manufacturing 
process. In even greater particularity it may be understood that the 
present invention is an apparatus for placing and retrieving circuit 
boards into a stacked vertical array. 
BACKGROUND OF THE INVENTION 
Printed circuit board manufacturing processes typically require many stages 
of production, from the formation of the "board" to the etching of the 
wiring pattern on the board to the insertion of the various electronic and 
electrical components on the board. In some stages of production, the 
individual boards are processed more rapidly than in others. Additionally, 
shift changes and supply and demand considerations sometimes make it 
necessary to store circuit boards. 
Typically, the production facility will include numerous conveyors which 
move the boards from one area to another for processing, attachment of 
components, and the like. Frequently, circuit boards are transported 
between conveyors by placing them in vertical magazines and transporting 
the magazine and contents to the appropriate location. Magazine loaders 
and unloaders are well known in the industry. The devices typically 
include an elevator for raising and lowering the magazine relative to the 
conveyor which delivers the boards or receives the boards in the magazine. 
In the norm, the magazines are delivered on conveyors themselves such that 
a rather large "footprint" or floor space is occupied by the apparatus. 
Typically the foot print is further enlarged by a secondary input and/or 
output conveyor. In all known examples of magazine loaders and unloaders, 
the circuit boards are pushed into and out of registry in the magazine, 
thus proper alignment of the magazine and implement used to push the board 
is necessary to prevent jamming. 
A further discussion of the background is presented in U.S. Pat. No. 
4,725,182, issued in 1988. The device disclosed therein represents an 
improvement over the devices which move the magazine vertically for 
loading and unloading, however, the device has failed to gain acceptance 
and is believed to be deficient in its ability to reliably place and 
retrieve boards from a magazine. 
SUMMARY OF THE INVENTION 
It is the principal object of the present invention to provide a small 
footprint apparatus for loading and unloading magazines in a printed 
circuit board assembly line. 
It is another object of the invention to provide capacity to load or unload 
up to four magazines at a time in a footprint of less than 18 inches in 
length which is very important in factories that do not have abundant 
space for manufacturing lines. 
It is another object of the invention to simplify and economize the 
magazine loading operation. 
It is another object of the invention to provide both a magazine loader and 
a magazine unloader in the same device. 
It is yet another object of the invention to provide a magazine loader and 
unloader that is not line dependent, but rather can be moved from one line 
to another within a facility to meet the changing needs of the user. 
These and other objects and advantages of the present invention are 
accomplished through the unique combination of sensory and control 
technology which allow the apparatus to repetitively and accurately 
retrieve and position circuit boards between the magazine and the assembly 
line. Specifically, my apparatus comprises a dedicated elevator having a 
"smart" handler mounted thereon to move the boards from the assembly line 
to the magazine and back. In as much as the dedicated elevator need only 
be the size necessary to handle the expected board size, the foot print is 
greatly reduced over apparatus which must move and elevate entire 
magazines. The smart handler both inserts boards into the magazine and 
retrieves the boards from the magazine. 
The smart handler includes a photosensitive gripper/pusher which can detect 
the edge of a board and grip the board by the detected edge to retrieve it 
from a slot in a storage assembly. The handler includes means for moving 
the gripper along the direction of movement of the board for a 
predetermined distance to detect and engage boards which are irregularly 
stacked in the magazine apparatus. The handler further includes a edge 
type conveyor which delivers boards to the gripper for full insertion into 
the storage assembly and receives boards from the gripper for delivery to 
the assembly line. A plurality of sensors and control elements monitor the 
position of the board and the components to accurately position the 
cooperative elements.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
It is to be understood that the apparatus claimed is a component to be used 
in an assembly process to facilitate the storage of circuit boards C or 
boards as they may be referred to, and the like in a magazine or in a 
buffer. The boards C may be stored at any convenient stage of completion 
with or without electrical or electronic components inserted on the board. 
The boards may be stored simply for time management purposes or for 
transportation from one area to another. Consequently, the apparatus used 
in conjunction with the remainder of the assembly of the printed circuit 
board are not a part of this invention and no specific description will be 
attempted. The present invention interfaces with the other assembly 
apparatus at the end of an infeed or outfeed conveyor. 
Referring to the drawings for a clearer understanding of the invention, it 
may be seen in FIG. 1 that a line conveyor 11 is disposed at a 
predetermined height H, typically an industry standard height. The 
conveyor 11 will be considered as an infeed or outfeed conveyor for the 
delivery or removal of boards from the apparatus to be described. It will 
be appreciated that the apparatus is expected to be able to handle boards 
C varying in width from three inches to eighteen inches and in length from 
three inches to eighteen inches. Also associated with the apparatus is at 
least one magazine 12. It is contemplated that up to four magazines may be 
serviced by the apparatus with a pair located above height H and a pair 
below height H with the pairs being vertically aligned. In the Fig.'s 
depicting more than one magazine, the magazines are designated as 12a, 
12b, 12c, 12d. Each magazine 12 is intended to have up to fifty usable 
board slots 13, spaced ten mm apart, defined by opposed internal flanges 
14 which are used to support circuit boards C in the conventional manner. 
It is intended that the boards be delivered or removed at least as often 
as every fifteen seconds, thus the apparatus must have a cycle time of 
less than fifteen seconds. 
Again referring to FIG. 1, it will be seen that an upright frame 16 is 
provided for the support of a platform 17. It will be appreciated that 
frame 16 will support suitable enclosing panels which will minimize the 
opportunity for interference with the internal workings of the apparatus. 
Frame 16 is generally rectangular and extends upwardly from the surface on 
which conveyor 11 is mounted to a height sufficient to service a magazine 
12 or buffer mounted at an 15 operable height above conveyor 11. Mounted 
within frame 16 on appropriate frame members is a lift motor 20, which is 
a servo motor with brake and encoder built in. Such motors are built by 
manufacturers such as Yaskawa and their operation including braking and 
encoding are understood in the art. A high speed servo motor is required 
for the lift to enable the apparatus to operate at less than 15 second 
cycle time. A servo motor controller 21, also available from Yaskawa, is 
conventionally associated with motor 20 as is an output gearbox 22 which 
is connected to a toothed drive pulley 23 about which a drive belt 24 is 
entrained. Drive belt 24 is a gear belt and is entrained about two toothed 
screw pulleys 26, each of which is affixed to an associated drive screw 27 
extending vertically within and supported in appropriate bearings 28 by 
frame 16. As will be appreciated, the rotation of the drive screws 27 is 
concomitant and can be precisely controlled using servo motors 20. 
A pair of lift nuts 25 are threadedly engaged on screws 27 at a common 
height and are affixed to a carriage assembly 30, which supports platform 
17, such that rotation of the screws 27 results in vertical displacement 
of the assembly 30. A pair of guide rods 29 are vertically disposed in 
frame 16 are also engaged by carriage assembly 30 such the carriage is 
constrained to remain horizontally level during vertical movement induced 
by the screws 27. It will be appreciated that frame 16 will be sized in 
accordance with the number of magazines serviced and thus screws 27 and 
guide rods 29 may be spaced laterally further apart when two magazines 12a 
and 12c are placed side by side. Accordingly, carriage assembly 30 will be 
fabricated in different transverse widths for the various embodiments. 
Platform 17 is supported on carriage assembly 30. 
Platform 17 includes a base plate 31 and a slide plate 32 which is 
adjustable relative to base plate 31, both of which are mounted on a pair 
of slide bars 34. Base plate 31 and slide plate 32 support the elevated 
platform conveyor 61. Supported on base plate 31 is a manual width 
adjustment assembly which includes a support 62 and a track 60. Supported 
for lateral adjustment on track 60 is a belt conveyor assembly 61a which 
is alignable with one run of conveyor 11. Supported at the same height and 
parallel to belt conveyor 61a is belt conveyor assembly 61b which is 
aligned with the other run of conveyor 11. By adjusting the spacing 
between the conveyor assemblies 61a and 61b any width of board C presented 
by conveyor 11 may be accommodated on platform 17. It will be appreciated 
that the engagement of board C on the conveyor 61a, 61b is in a plane at a 
height above slide plate 32. Mounted to slide plate 31 subjacent the plane 
of conveyors 61a, 61b is a gripper travel assembly 35 including a linear 
actuator 63 mounted for extension and retraction parallel to conveyors 
61a, 61b actuator 63 may be any suitable actuator. A vertically aligned 
linear actuator 70 is affixed to the gripper travel assembly 35 and 
movable therewith. Affixed to and movable vertically by actuator 70 is a 
gripper assembly 64 such as manufactured by Tolomatic having a set of jaws 
65 which can engage the edge of a board C. It may be seen that the gripper 
assembly 64 may be positioned horizontally and vertically by the 
combination of the linear actuators. 
A set of sensors and switches are provided to monitor the position of the 
gripper and the interaction thereof with boards C. Switch 71 is mounted in 
conjunction with gripper assembly 35 to indicate when the gripper is 
proximal the end of infeed conveyor 11. Switch 72 is mounted in 
conjunction with actuator 63 to indicate when actuator 63 has been 
extended sufficiently to release the board C to the magazine or to 
normally engage a board C positioned in the magazine. Switch 73 is mounted 
in conjunction with actuator 63 to indicate that actuator 63 has reached 
full extension. Switch 74 is mounted in conjunction with actuator 63 to 
indicate actuator 63 has reached a midstroke position. Switch 75 is 
mounted to the gripper assembly 64 to indicate that the gripper jaws 65 
are open. A switch 76 is likewise mounted to indicate that the jaws 65 are 
closed. Switches 77 and 78 are mounted in conjunction with actuator 70 to 
indicate when the gripper assembly 65 is at the up and down position 
respectively. A through scan fiber optic sensor 91 is mounted to the 
conveyor assembly 61 to indicate the presence of a board C at the end 
proximal the infeed conveyor 11. A similar sensor 92 is mounted proximal 
the midpoint of the conveyor assembly to indicate the presence of a board 
at this position, and a third fiber optic sensor 93 is mounted at the end 
of the conveyor proximal the magazine to detect the presence of a board at 
that location. A fiber optic sensor or optical sensor 94 is carried on a 
channel shaped sensor mount 95 affixed to the gripper assembly 65. The 
sensor mount has an upper and lower leg 96 and 97 and a rear wall 98 such 
that a channel 99 is formed parallel to and opening in the same direction 
as the gap between the gripper jaws 65 
Similarly various sensors are utilized to indicate cooperative positioning 
of the remaining components used in transferring the boards C. Upper and 
lower over-travel switches 101 and 102 indicate that the platform is at 
its vertical displacement limit. Magazine loaded switches 103 and 104 
indicate that the magazines are properly positioned. Switch 106 indicates 
that the platform is at the home position adjacent and aligned with 
conveyor 11. Switch 107 indicates that the platform is near the home 
position. Through scan optical sensors 108 and 109 are to indicate proper 
alignment of the magazines 12 and the presence of boards C extending 
therefrom in to the vertical path of platform 16. All of the sensors 
provide input signals to a programmable logic device 111 which is 
programmed to execute stored programs and control the movement of the 
apparatus to load or unload boards. 
With the forgoing in mind the structure and operation of the apparatus may 
be more fully understood with reference to the drawings and the flow chart 
presented in FIG. 6A and 6B. As may be seen in the flow chart, loading of 
a magazine 12 commences with gripper travel assembly 35 at the home 
position with switches 71, 75, and 78 made indicating that actuator 63 is 
retracted and the gripper jaws are open. The operator installs a magazine 
in the selected receiver and thus makes switch 103 or 104. If the optical 
sensor 108 or 109 is covered by the magazine or anything in the magazine, 
the logic device 111 disables the lift and the platform will not move 
vertically. If the sensor is clear and the path of the platform is clear, 
the platform will move into alignment with the infeed conveyor 11 making 
switch 106. A sensor on the infeed conveyor indicates the presence of a 
board C to be delivered to the loader and signals for the platform 
conveyor 61 to commence running toward the magazine 12. A board C is thus 
passed from infeed conveyor 11 to platform conveyor 61 for movement toward 
the magazine. When optical sensor 91 indicates to logic device 111 that 
the trailing edge of board C has cleared the interface between conveyors 
11 and 61, conveyor 61 is stopped and motor 20 is energized. As noted 
above motor 20 is a servo motor engaged with a pair of drive screws 27 
through appropriate connections such that the motor and hence the rotation 
of the screws are precisely controllable. In this apparatus the motor and 
screw are calibrated such that the platform conveyor 61 is precisely 
displaceable from alignment with the infeed conveyor 11 to alignment with 
a selected slot in a magazine 12. Accordingly, when Board C is on conveyor 
61, and motor 20 is energized, it drives the screws 27 to displace the 
conveyor 61 in alignment with the proper slot in magazine 12. 
When the servo motor controller 21 indicates that the motor has stopped, 
conveyor 61 resumes running toward the magazine thereby partially urging 
board C into magazine 12. As the board C clears optical sensor 92 at the 
midpoint of conveyor 61, a pair of solenoids 121 and 122 are energized to 
control the valving of actuators 63 and 70 such that the actuators are 
extended such that the gripper assembly up switch 77 is made to indicate 
that the gripper assembly is raised to the proper height. In the load mode 
the gripper does not close on the edge of the board C, thus as the gripper 
jaws 65 receive the edge of the board C, the edge is simultaneously 
received within channel 99 of the sensor mount. As actuator 63 is 
extended, back wall 98 abuts the proximal edge of the board C and 
positively urges the board into magazine 12. Switch 72 is made when 
actuator 63 has extended sufficiently to properly place the board C in the 
magazine, whereupon switch 72 signals logic device 111 to stop platform 
conveyor 61 and initiate retraction of actuator 63. If optical sensor 94 
indicates that the board has disengaged from channel 99 and gripper jaws 
65 when midstroke switch 74 is made, then these signals to logic device 
111 initiate retraction of actuator 70 to lower gripper assembly 64 until 
"down" switch 78 is made. If the magazine overhang optical sensor is not 
obscured, then the lift motor 20 returns the platform conveyor 61 to it 
home position aligned with the infeed conveyor. Switch 71 is made by the 
proper retraction of actuator 63 and the cycle is repeated for the next 
board until the magazine 12 is filled. 
It should be appreciated that the cycle time is less than fifteen seconds 
and the logic device 111 is programmable to control the lift to align 
platform conveyor 61 with the slots in the magazine 12 to accommodate 
boards which have components of various heights thereon. 
When the apparatus is used as an unloader the sequence is as follows. The 
operator delivers a magazine 12 to the frame and positions it such that 
switch 103 is made and moves a board gauge 141 supported by frame 16 into 
position adjacent the front of the magazine 12 to grossly align the boards 
C. The logic device 111 is programmed by the operator, or a prerecorded 
program is selected for the device such that the lift position and other 
parameters, such as the number and sequence of the magazines to be 
unloaded are known to the logic device. The lift begins with platform 
conveyor at the home position adjacent outfeed conveyor 11, with switches 
71 and 78 made to indicate that the gripper assembly is at the home 
position and switch 75 made to indicate that gripper jaws 65 are open. If 
the magazine overhang optic sensor 108 is not obscured, then operation can 
proceed. The gauge is retracted to a storage position. Servo motor 20 
advances platform conveyor 61 into alignment with a slot containing a 
board C, whereupon solenoids 121 and 122 are energized to extend actuator 
63 and raise the gripper assembly 64 to the up position making switch 77. 
As actuator 63 is extended, it moves the raised gripper assembly 64 with 
the gripper jaws 65 open, such that a board C in magazine 12 may be 
received within the jaws 65 and concomitantly within channel 99. When the 
board is received within channel 99, it obscures optical sensor 94 which 
initiates the energization of solenoid 123 to close jaws 65, thereby 
gripping board C along an edge margin thereof. Sensor 94 also signals for 
the reversal of the actuator 63 and for the beginning of platform conveyor 
61 running toward the outfeed conveyor 11. It should be understood that if 
the actuator 63 extends to the full permitted range of travel, that is to 
say if it makes switch 73, without engaging a board which is detected by 
sensor 94, then the board for that magazine slot is positioned beyond the 
search range of the apparatus and an alarm is generated which may stop the 
apparatus or merely alert the operator. In the preferred embodiment the 
search range is set at two inches beyond the expected travel of the rod 
thus switch 73 is two inches beyond switch 72. 
An engaged board C is pulled from the magazine by gripper assembly 64 due 
to the retraction of actuator 63 and is delivered onto platform conveyor 
61. Gripper jaws 65 remain engaged on board C until midstroke switch 74 is 
made whereupon the jaws open and the board C is moved only by conveyor 61. 
When optical sensor 94 indicates that channel 99 and jaws 65 have 
retracted beyond the edge of board C, then actuator 70 retracts returning 
the gripper assembly to its lower position, making switch 78, and clearing 
the path for conveyor 61 to deliver the board to the end of the conveyor 
closest to outfeed conveyor 11. When optical sensor 91 is detects the 
presence of board C, conveyor 61 is stopped and magazine overhang sensor 
108 is clear, then, the lift returns platform conveyor 61 to alignment 
with conveyor 11, making switch 106. When conveyor 61 and conveyor 11 are 
aligned conveyor 61 delivers board C to conveyor 11 and runs until the 
board is completely within the control of the outfeed conveyor. The 
sequence is repeated as needed to remove all the boards from the magazine. 
As noted hereinabove, the magazine 12 may have separate magazines 12a to 
12d in an array. Magazines in a vertical array may be serviced by the 
apparatus simply by programming the logic device 111 to control the 
vertical displacement of the platform conveyor 61 appropriately and by 
providing sensors at appropriate locations. As seen in FIG. 7, to enable 
side by side magazine service, platform 17 incorporates a transversely 
mounted linear actuator 151 affixed to carriage assembly 30 and to base 
plate 31, such that base plate 31 may be selectively urged along a set of 
rails 152 to a first position and an offset position, wherein the offset 
position aligns the platform conveyor with laterally offset magazines 12a 
and 12b. The lateral shift of the base plate and slide plate would be 
sequenced in the same manner as the vertical movement of the platform. 
It will be further understood that slide plate is 32 displaceable relative 
to base plate 31 along slide bar 34 to enable the gripper jaws to be 
displaced relative to the width of platform conveyor 61 to engage the edge 
of a board at a selectable position to avoid interference with components 
mounted on the board. The slide plate is fixed in the selected position 
with slide nuts 40. 
The forgoing description is intended by way of illustration and is not 
intended to limit the invention in any manner inconsistent with the scope 
of the claims presented herewith.