An apparatus for lifting, carrying, and positioning probemats or fixtures. The apparatus comprises movable opposing side arms having a mechanism for receipt of a fixture handle, as well as a stationary support member. An arrangement is provided to connect the side arms to the support member by the use of a first track positioned on the front of the support member and a second track positioned on the rear of the support member. First and second rollers for rolling engagement with the tracks are connected to each side arm to support the weight of the side arm and to permit each side arm to slidably move along the tracks. The fixture handler also includes jaws comprising a channel and stops at the ends of the channel to permit the handler to be used with a plurality of different fixtures handles. Finally, an insert is provided for use with the jaws to further enhance the ability of the fixture handler to support a myriad of fixture types.

FIELD OF THE INVENTION 
The present invention relates to the field of probemat or fixture handling, 
and in particular to an apparatus for lifting, carrying and positioning 
probemats or fixtures. 
BACKGROUND OF THE INVENTION 
Today, it is common to subject printed circuit boards to a wide variety of 
test procedures and environments, including the performance of electrical 
tests to ensure the quality and reliability of the circuit. Generally, 
electrical testing is accomplished by the use of programmable automatic 
test equipment (ATE). ATE systems are capable of providing necessary 
inputs to the circuit and measuring the outputs resulting by application 
of those inputs to ascertain whether the circuit is properly performing. 
To permit ATE equipment to be used with a plurality of different printed 
circuit boards, an array of electrical contact points (a "bed of nails") 
are provided. Thus, to test a particular circuit, the inputs and outputs 
of that circuit must necessarily be electrically connected to the array of 
contacts on the ATE. This is accomplished by placing the printed circuit 
board into a fixture or probemat built for that circuit. 
An ATE fixture or probemat is circuit specific as the specific inputs and 
outputs of the circuit must ultimately be connected to the electrical 
contacts of the ATE. Several types of probemats have been developed to 
deal with the circuit specificity. Conventional probemats are those only 
having enough electrical contacts for testing the particular circuit, 
i.e., contacts corresponding to only the inputs and outputs of the 
circuit. As explained in U.S. Pat. No. 4,774,462, however, such probemats 
are costly, time consuming to produce (thereby delaying production 
schedules), require considerable storage space when not in use, and are 
bulky and heavy, posing handling problems for personnel responsible for 
loading or unloading such fixtures. 
In response to these shortcomings, universal probemats were developed. 
Universal probemats usually contain an array of electrical contact points 
capable of connection with each of the contacts in the array of the ATE. 
Universal probemats are not, however, without drawbacks themselves. Large 
forces are required to connect the fixture to the ATE, the fixture cannot 
be used on boards whose test points do not lie on the array, and a large 
capacity, expensive ATE system is generally required. An example of a 
universal probemat is found in U.S. Pat. No. 4,357,062. 
Another type of probemat uses a special programming card (specific for each 
different printed circuit board type) to connect the board to the grid of 
electrical contacts of the probemat. Yet another type uses offset probes 
which provide connection to the ATE system (see U.S. Pat. No. 4,774,462, 
for example). 
Regardless of the type of probemat employed, a mechanism must be provided 
to move the probemat into position in the ATE and to remove the probemat 
from the ATE. Many systems require that a human place the probemat onto 
the ATE, though some automated systems are provided. In U.S. Pat Nos. 
5,104,277 and 5,094,584, for example, an automated system for storing, 
retrieving, and loading test fixtures from a storage facility to the ATE 
is disclosed. Essentially, the probemats used with this apparatus have 
edges capable of receipt by the horizontally extending opposing tracks of 
the storage apparatus and of the transporting apparatus of the system. 
Robotics technology is used to move the probemats. 
U.S. Pat. Nos. 5,055,779, 4,993,136 and 4,818,933 disclose a system for 
handling and testing a printed circuit board having devices at fixed 
predetermined locations. The system includes a conveyor for moving the 
board from a remote position into the test position of the ATE. In this 
system, the probemats have handles extending from the edge thereof for 
placement of the probemat onto the conveyor of the apparatus. 
Neither of these loading systems addresses the problems associated with the 
general transport of probemats. Many ATE systems do not provide a 
mechanism for automatic loading of the fixture onto the test bed. Further, 
even if such a loading system exists, it is still necessary place the 
fixture onto the loading means, or perhaps into the storage means, as in 
U.S. Pat. Nos. 5,055,779, 4,993,136 and 4,818,933. 
As previously stated, probemats are often heavy and bulky. Thus, requiring 
personnel to lift and transport probemats places the person, the probemat 
and the circuit at risk. The person handles the probemat at the risk of 
incurring injury. The probemat and circuit may be damaged as improper 
handling may cause physical damage to the probemat or the circuit, or the 
inadvertent introduction of electrical current to the probemat and/or 
circuit may damage the electronic components of the printed circuit board 
or the probemat itself. Therefore, it is desirable to provide an apparatus 
for lifting and transporting probemats to reduce the potential for harm to 
an individual or to the probemat or circuitry as may result if lifted and 
carried by an individual. 
Regardless of whether an ATE system includes an automatic loading 
mechanism, it is still necessary for the probemat to be placed into proper 
position. This may include placement of the probemat at an angle 
corresponding to the angle of the ATE system. For example, the test beds 
of Hewlett-Packard's HP 3070 and HP 3065 ATE systems are at an angle. 
Therefore, it is desirable to provide an apparatus suitable for placement 
of the probemat in a predetermined position, including an angled position. 
Probemats vary in size, shape, and weight and also vary in the type of 
mechanism provided for transport of the probemat. The size, shape and 
weight are determined by many factors, including the type of circuit being 
testing, the type of ATE equipment, and whether an automatic handling 
system is used in connection with or as a part of the ATE system. The 
probemat often contains handles intended for use by humans when carrying 
the probemat. For example, the Hewlett-Packard SL L303 probemat includes 
handles of a particular shape and length. (See FIGS. 7A-7B herein). To 
transport this probemat, Hewlett-Packard suggests that it customers 
purchase the Alum-A-Lift Model 200TF lift available from Alum-A-Lift in 
Winston, Ga. and an end-effector (Product No. 44813A) from 
Hewlett-Packard. The combination of the lift and end-effector are, 
however, specific to the Hewlett-Packard ATE systems and Hewlett-Packard 
probemats having handles of a particular shape and dimension. Unless 
modification is made to the apparatus, it cannot lift and position other 
probemats. It is therefore desirable to provide an apparatus for lifting, 
transporting and positioning a probemat that may be used with a plurality 
of different probemat types including those of differing shapes, sizes, 
and weights, and those recommended for use in various ATE systems. 
SUMMARY OF THE INVENTION 
The present invention provides an apparatus for transporting and 
maneuvering probemats or fixtures used with automatic test equipment for 
testing printed circuit boards. 
According to the present invention, a universal fixture handling apparatus 
is provided. The universality of the apparatus arises, in part, from the 
handler's ability to raise, lower and tilt a fixture held between the jaws 
of the handler. The jaws are also of a form suitable to receive a myriad 
of known fixture handles or edges intended for holding the fixture. 
Specifically, each jaw comprises a formed channel having stops at each end 
of the channel, and is of a length and overall dimensions to accommodate 
numerous handle types. For those fixtures handles which do not fit into 
the channel of the jaw, the invention discloses an insert used in 
conjunction with the jaw. The jaw insert is shaped to be received by the 
channel of the jaw, and to extend outside the jaw. The portion of the jaw 
extending outside the jaw receives the fixture handle. Thus, various 
configurations of jaw inserts may be used in conjunction with the jaw of 
the present invention. 
An arrangement for connecting the side arms of the handler to the support 
member of the handler is also provided with the present invention. Tracks 
are provided on both the front and the back of the support member for 
rolling engagement with rollers connected to the side arm. This 
configuration supports the weight of the side arm while permitting for 
easy sliding of the side arm with respect to the support member. This 
arrangement reduces the amount of physical stress placed on the rollers, 
tracks and support members when compared to prior art fixture handling 
systems. 
The fixture handler of the present invention is comprised of relatively few 
components, resulting in a handler that is inexpensive to manufacture. 
Further, the use of "off-the-shelf" components assists in creating a 
reliable units, as well as in minimizing the costs associated with the 
operation, repair and maintenance of the fixture handler. The simplicity 
of structure limits the overall dimensions of the handler to enhance its 
maneuverability. Also, the provision of a low-cost handler encourages the 
use of such an apparatus for lifting, carrying and positioning fixtures, 
rather than using human labor for such tasks, thereby reducing the 
possibility of injury to persons or to the fixture or a printed circuit 
board held by the fixture. 
The above discussed features, as well as additional features and advantages 
of the present invention, will become more readily apparent by reference 
to the following detailed description and the accompanying drawings.

DETAILED DESCRIPTION OF THE DRAWINGS 
FIGS. 1 and 2 illustrate front and rear perspective views, respectively, of 
one embodiment of the probemat handler according to the present invention. 
In this embodiment, probemat handler 20 comprises frame 22 including lower 
frame assembly 24 having wheels 25-28 rotatably attached thereto. Also 
attached to lower frame assembly 24 are first and second upright support 
members 29 and 30. Joining first and second upright support members 29 and 
30 are first and second cross-support members 31 and 32 and top support 
member 33 as shown. Handle 34 is attached to first and second upright 
support members 29 and 30 to assist in maneuvering frame 22 and to protect 
an operator from the moving parts of hoist system 36, described in further 
detail herein. 
It will be appreciated by those of skill in the art that frame 22 of 
probemat handler 20 is skeletal in nature, providing a lightweight, 
portable unit. Further, with the exception of the handling mechanism 
described in further detail herein, frame 22 is narrow and with little 
depth, thereby permitting probemat handler 20 to be easily maneuvered to, 
from and near an ATE system. Also, skeletal frame 22 does not obstruct the 
vision of an operator positioned behind frame 22 when the operator is 
lifting, carrying or positioning a probemat held in the handling mechanism 
of probemat handler 20. 
In addition to frame 22, probemat handler 20 includes hoist system 36 and 
handling assembly 50. In this embodiment hoist system 36 comprises a 
modified hydraulic hoist, such as Model No. DPL-54-2222, manufactured by 
Wesco Manufacturing Co., and available from Associates Material Handling 
of Denver, Colo. Hoist system 36 includes hydraulic pump and cylinder 38 
actuated by foot pump 40. Pump and cylinder 38 is connected to one end of 
chain 42. The other end of chain 42 is operatively connected to base plate 
52 of handling assembly 50. Chain 42 also extends over pulley 44 which is 
connected to the top end of the hydraulic shaft. 
Base plate 52, which supports handling mechanism 50, is slidably connected 
to first and second vertical support members 29 and 30 by first and second 
braces 54 and 56 (see FIG. 2). First brace 54 includes first and second 
cam followers 57 and 58, respectively, as shown in FIG. 3A, for sliding 
engagement with first vertical support member 29. Second brace 56 also 
contains two cam followers (not shown) for sliding engagement with second 
vertical support 30. 
Thus, hoist system 36 is used to raise or lower handling system 50. 
Specifically, actuation of foot pump 40 to cause extension of hydraulic 
cylinder 38 results in lowering base plate 52, and hence, handling system 
50, along vertical support members 29 and 30. Actuation of foot pump 40 to 
cause retraction of hydraulic cylinder 38 results in raising handling 
system 50 along vertical support members 29 and 30. 
It will be appreciated that other mechanisms may be used to raise and lower 
handling mechanism 50 of the present invention. For example, a 
rechargeable electric battery source, such as that employed in the 
Alum-A-Lift Model 200TF, may be used. However, the hydraulic system of the 
present embodiment may be advantageous over other sources of power as it 
provides sufficient and accurate control over the raising and lowering of 
handling mechanism 50 while maintaining simplicity of operation. A 
hydraulic power source such as hoist system 36 also limits the cost of 
operation, maintenance and repair of the power source. Further, hoist 
system 36 is lightweight and compact thereby enhancing the portability of 
probemat handler 20. 
As shown in FIG. 1, handling mechanism 50 includes first and second jaws 60 
and 62 for holding a fixture probemat therebetween. Generally, all 
probemats have either handles or formed edges at opposing edges thereof 
which are intended for use in transporting the probemat. Jaws 60 and 62 
are intended to receive such handles or edges. First and second jaws 60 
and 62 are operatively connected to base plate 52 by first and second side 
arms 64 and 66, respectively. As is described in further detail herein in 
association with FIGS. 4-9, jaws 60 and 62 are capable of holding a 
variety of probemat types and sizes, and are also capable of being tilted 
at an angle with respect to probemat handler 20 to permit angular 
placement of a probemat onto an ATE system, if so desired or required. 
Referring now to FIG. 3A, there is illustrated a partial side view of the 
point of engagement of one side arm of the probemat handler to the base 
plate of the probemat handler. Specifically, the connection of first side 
arm 64 to base plate 52 is illustrated in FIG. 3A. Second side arm 66 is 
connected to base plate 52 in a like manner, as shown in FIGS. 1-2. In 
this embodiment, first side arm 64 is connected to and extends 
perpendicular away from vertical slide plate 68. Connected to and 
extending perpendicular from vertical slide plate 68 is horizontal slide 
plate 70. First and second guide wheels 72 and 74, respectively are 
connected to the rear side of vertical slide plate 68. Third guide wheel 
76 is connected to horizontal slide plate 70. Attached to base plate 52 is 
middle guide rail plate 78, which, as shown in FIG. 1, extends the entire 
length of base plate 52. 
Attached to middle guide plate 78 are first and second guide rails 80 and 
82, respectively, both of which extend the entire length of middle guide 
plate 78 and hence the entire length of base plate 52. First guide rail 80 
is located below second guide rail 82 and is positioned for engagement 
with first guide wheel 72. Second guide rail 82 is positioned for 
engagement with second guide wheel 74. Connected to the top rear edge of 
base plate 52 and extending the entire length of base plate 52 is third 
guide rail 84. Third guide rail 84 is positioned for engagement with third 
guide wheel 76. As seen in FIGS. 1-2, first, second and third guide wheels 
72, 74 and 76 are actually representative of first, second and third sets 
of guide wheels. In the embodiment of FIGS. 1-2, the first set of guide 
wheels comprises three wheels positioned along the horizontal axis of 
middle guide plate 78 to engage first guide rail 80; the second set of 
guide wheels comprises three wheels positioned along the horizontal axis 
of middle guide plate 78 to engage second guide rail 82; and the third set 
of guide wheels comprises three wheels located on the underside of 
horizontal slide plate 70 to engage third guide rail 84. The use of three 
wheels to engage each rail provides substantial contact points to support 
the weight of first side arm 64 and to prevent the combination of side arm 
64, vertical slide plate 68, and horizontal slide plate 70 from wobbling 
with respect to base plate 52. 
In this embodiment, the guide wheels are of the type known as DualVee.TM. 
guide wheels, manufactured by Bishop-Wisecarver Corp., and available from 
Moore Bearing of Denver, Colo. The guide rails are also manufactured by 
Bishop-Wisecarver Corp. and are intended for use with the DualVee.TM. 
guide wheels. The use of guide rails 80, 82 and 84 with guide wheels 
allows first side arm 64 to move easily in a horizontal direction. The 
presence of third guide rail 84 and the set of third guide wheels 76 is 
particularly important in assisting to distribute the weight of first side 
arm 64 along the horizontal axis of base plate 52, and in stabilizing the 
position of first side arm 64 with regard to base plate 52 and frame 22. 
Prior art systems, such as the Alum-A-Lift lifting apparatus, only 
provides two guide rails--each of 20 which is located on the front surface 
of the base plate. Such an arrangement results in the placement of a great 
deal of stress on the base plate, tends to warp the guide rails and/or 
guide wheels, and may result in the side arms tilting downward away from 
the base plate or in the base plate tilting downward away from frame 22. 
Specifically, the wheels contact the track such that a great deal of force 
(created by the weight of the side arm and any probemat held therein) is 
applied normal to the plane of the wheel (along the axis of rotation of 
the wheel). In the present invention, use of the guide wheels behind the 
base plate places the force of the weight of the side arm and any probemat 
along the radial axis of the guide wheel, pressing the wheel against the 
track. 
It will be appreciated by those of skill in the art that the number wheels 
used to connect a side arm to the base plate may vary. It is possible, for 
example, to only require one wheel for engagement with a track, rather 
than the three wheels shown in the embodiment of FIGS. 1-3. The number of 
wheels desired is likely dependent on the weight of the side arms and the 
weight of probemats to be handled by probemat handler 20. 
It will also be appreciated that the specific types of tracks and wheels 
need not be as shown in FIGS. 1-3A. The track must provide a contact means 
for a rolling means, such as a wheel or a roller, for sliding engagement 
of the side arm to the base plate. For example, in FIG. 3B, there is shown 
a partial side view of a second embodiment of the connection of first side 
arm 64 to base plate 52 of handling mechanism 50. First, second and third 
wheels 73, 75 and 77 engage one or more contact surfaces of first, second 
and third tracks 81, 83 and 85 as shown. No middle plate 78 is needed in 
the embodiment of FIG. 3B. 
Now, referring again to FIG. 1, the connection of first side arm 64 to 
second side arm 66 is shown. Specifically, extending through first side 
arm 64 is first lead screw 86 and extending through second side arm 66 is 
second lead screw 88. First and second lead screws 86 and 88 are rigid and 
may comprise steel lead screws such as the Power-ac acme screws, Model 
5/8--8 Single Start, manufactured by Nook Industries and available from 
Moore Bearing of Denver, Colo. The threads of first lead screw 86 and the 
threads of second lead screw 88 are oriented in opposition to each other. 
First and second lead screws 86 and 88 are joined together at lead screw 
joint 90. Crank 92 is connected to one end of second lead screw 88 to 
permit simultaneous rotation of first and second lead screws 86 and 88. 
Rotation of crank 92 in one direction causes first and second side arms 64 
and 66 to move away from each other and away from the lead screw joint 90. 
Rotation of crank 92 in the opposite direction causes first and second 
side arms 64 and 66 to move toward each other and toward lead screw joint 
90. 
It will be appreciated by those of skill in the art that the horizontal 
translation of first and second side arms 64 and 66 is easy to achieve and 
control. The use of lead screws is not only cost effective, it provides 
for accurate separation of first and second side arms 64 and 66 to 
accommodate a plurality of probemats which vary in width. Further, it will 
be appreciated that, if desired, power sources other than the manual crank 
illustrated in this embodiment may be used to cause translational movement 
of first and second side arms 64 and 66. For example, an electric motor 
may be operably connected to either first or second lead screws 86 and 88 
to cause rotation of first and second lead screws 86 and 88. 
FIG. 4 illustrates an enlarged perspective view of one jaw of the probemat 
handler of the present invention. Second jaw 62 is rotatably connected to 
second side arm 66 at tilting bearing 91. When in the horizontal position 
as shown in FIG. 4, one end of second jaw 62 rests against stop 93. 
Rotation of second jaw 62 with respect to second side arm 66 is 
accomplished by movement of lever 94 pivotally connected to side arm 66 at 
pivot 96. Lever 94 is also connected to connecting arm 98. Connecting arm 
98 is pivotally connected to second jaw 62 as shown, such that rotation of 
lever 94 about pivot 96 causes second jaw 62 to tilt with respect to 
second side arm 66 about tilting bearing 91. In this manner, second jaw 62 
may be placed at an angle for placement of a probemat held by second jaw 
62 onto a non-horizontal surface as is found in some ATE systems. 
In the embodiment discussed herein, first jaw 60 is pivotally connected to 
first side arm 64, and a stop similar to stop 93 on second side arm 66 is 
present to stop rotation of first jaw 60 beyond a horizontal position. The 
pivotal connection of first jaw 60 to first side arm 64 is free, 
permitting tilting of first jaw 60 is response to tilting of second jaw 62 
when a probemat is placed in jaws 60 and 62. No other physical connection 
is present between first and second jaws 60. However, it is possible, and 
considered to be within the scope of the invention, that first and second 
jaws 60 and 62 could be physically connected to each other such that use 
of lever 94 to tilt second jaw 62 also causes tilting of first jaw 60 even 
when no probemat is held by first and second jaws 60 and 62. Such a 
physical connection is not necessary, however, for probemat handler 20 to 
be able to tilt a probemat at an angle, and therefore, such a physical 
connection adds unneeded cost to probemat handler 20. Such cost may, 
however, be justifiable, in the event probemat handler 20 is used with a 
flexible or fragile probemat, to reduce the stress invoked on the probemat 
caused by rotation of second jaw 62 about tilting bearing 91. 
The shape of second jaw 62 is made to accommodate a plurality of different 
probemat types. Referring to FIGS. 5A-7B, there are illustrated partial 
top and side views of three different types of probemats, each having a 
different type of handle by which the probemat is to be held when lifted, 
carried, positioned or placed. The probemat of FIGS. 5A-5B is similar to 
the GenRad 2186 probemat which weighs approximately 54 pounds. Probemat 
100 contains a handle which is shorter than the entire length of probemat 
100 and which extends outward and downward from the edge of probemat 100. 
The probemat 104 of FIGS. 6A-6B is similar to the MDA Probemat by M/Rel, 
Inc., weighing approximately 30 to 40 pounds. Handle 106 extends the 
entire length of probemat 104, and extends outward and downward as shown 
in FIG. 6B. Finally, probemat 108 of FIGS. 7A-7B is representative of the 
Model SL L303 probemat manufactured by Hewlett-Packard which weighs 
approximately 20 pounds. Probemat handle 110 contains two bends 111 
between and below which is positioned middle handle portion 112. 
Second jaw 62 forms channel 114 into which a probemat handle, such as those 
of FIGS. 5A-7B may be inserted. Further, at the opposing ends of second 
jaw 62 are formed first and second stop brackets 115 and 116 to stop a 
probemat handle from sliding outside of the jaw. In this embodiment, 
second jaw 62 also has formed on the exterior wall thereof, first and 
second concave slots 117 and 118 formed therein. First and second slots 
117 and 118 are positioned to receive bend portions 111 of the handle of 
the Hewlett-Packard probemat illustrated in FIGS. 7A and 7B. 
The channel of second jaw 62 is illustrated as U-shaped. It will be 
appreciated that the channel may be of another shape, such as V-shaped, 
cylindrical, etc., so long as the shape of the channel accommodates 
receipt of a variety of probemat handle types, lengths and shapes. 
To accommodate even more types of probemat handles, the present invention 
includes an insert for use with the jaw. FIG. 8 illustrates an enlarged 
perspective view of the jaw shown in FIG. 4 having one embodiment of the 
jaw insert inserted therein, and FIG. 9 illustrates a cross-sectional side 
view of the jaw and jaw insert taken at line C--C of FIG. 8. Jaw insert 
120 is formed to fit within channel 114 of second jaw 62 between first and 
second stop brackets 115 and 116. Insert 120 then forms shelf 121 
extending outside channel 114 and onto which a probemat handle or edge is 
placed. Thus, if the length of a probemat handle or edge exceeds the 
length between brackets 115 and 116 or if the handle is wider than channel 
114 is wide, use of insert 120 permits probemat handler 20 to be used. 
It will be appreciated by those of skill in the art that the jaw and jaw 
insert of the present invention allow the probemat handler to be used with 
a variety of probemat handle types. Inserts of shapes other than that 
illustrate in FIGS. 8-9 resting within the channel of the jaw may be used 
for specific handle types and are contemplated to be within the scope of 
the invention. The combination of the jaw and insert is advantageous over 
prior art systems requiring specific jaws to hold specific handle types. 
First, the jaw of the present invention is, without the insert, able to 
support a variety of probemat handle types. The addition of a simple, 
inexpensive insert assists in broadening the support of the jaw for other 
probemat types, such as those which may not fit into the channel of the 
jaw. 
It will also be appreciated that the probemat handler of the present 
invention is suitable for use with fixtures that are not known as or 
referred to as "probemats". The term "probemat", as used herein and in the 
claims, is intended to encompass fixtures used in connection with printed 
circuit boards and the like for the subsequent testing thereof. "Testing" 
encompasses electrical tests performed by an ATE system or other 
electrical apparatus, as well as environmental testing, such as those 
performed to measure the effects of vibration, moisture, temperature, and 
other physical variables. The term "handles" of a fixture or probemat, as 
used herein and in the claims, encompasses handles attached or formed on 
opposing edges, or opposing edges which are formed in the fixture or 
probemat itself.