U.S. patent application number 10/193029 was filed with the patent office on 2003-09-18 for in-circuit test fixture loader.
This patent application is currently assigned to Seagate Technology LLC. Invention is credited to Koh, Bee Siang, Kuah, Beng Kiat, Lim, Yeong Hwui, Siva, Kumar P..
Application Number | 20030175098 10/193029 |
Document ID | / |
Family ID | 28044448 |
Filed Date | 2003-09-18 |
United States Patent
Application |
20030175098 |
Kind Code |
A1 |
Koh, Bee Siang ; et
al. |
September 18, 2003 |
In-circuit test fixture loader
Abstract
An in-circuit test fixture loader includes a carrier that is
able to receive and support an in-circuit test fixture. The carrier
includes a pair of opposing side rails and an end rail between the
side rails. The side rails and the end rail are spaced to receive
the in-circuit test fixture between the side rails and against the
end rail. The loader also includes a fixture lock connected to the
carrier to prevent movement of the in-circuit test fixture away
from the end rail. A horizontal slider attached between the carrier
and a mechanism base includes guide shafts that guide the carrier
and the in-circuit test fixture in a first substantially horizontal
direction. A vertical slider of the loader is attached between the
carrier and the mechanism base. The vertical slider includes an
actuator that is operable to slide the carrier and the in-circuit
test fixture in a second substantially vertical direction between
an upper position and a lower position. The horizontal slider and
the vertical slider are able to guide the in-circuit test fixture
and the carrier between a receive position, wherein the in-circuit
test fixture may be loaded on the carrier, and a test position,
wherein a printed circuit board assembly supported by the
in-circuit test fixture may be tested. Also, a clamp mounted on a
testing base is able to selectively secure the in-circuit test
fixture to the testing base in the test position.
Inventors: |
Koh, Bee Siang; (Singapore,
SG) ; Kuah, Beng Kiat; (Singapore, SG) ; Lim,
Yeong Hwui; (Singapore, SG) ; Siva, Kumar P.;
(Singapore, SG) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Assignee: |
Seagate Technology LLC
|
Family ID: |
28044448 |
Appl. No.: |
10/193029 |
Filed: |
July 10, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60364775 |
Mar 15, 2002 |
|
|
|
Current U.S.
Class: |
414/222.06 ;
G9B/27.051; G9B/27.052; G9B/5.145 |
Current CPC
Class: |
G11B 5/455 20130101;
G11B 2220/20 20130101; G11B 27/36 20130101; G01R 31/2808 20130101;
G11B 27/34 20130101 |
Class at
Publication: |
414/222.06 |
International
Class: |
B65H 001/00 |
Claims
What is claimed is:
1. An in-circuit test fixture loader, the loader comprising: a
carrier operable to receive and support an in-circuit test fixture,
the carrier comprising a pair of opposing side rails and an end
rail between the side rails, the side rails and the end rail spaced
to receive the in-circuit test fixture between the side rails and
against the end rail; a fixture lock connected to the carrier
operable to selectively abut the in-circuit test fixture to prevent
movement of the in-circuit test fixture away from the end rail; a
horizontal slider attached between the carrier and a mechanism base
comprising guide shafts on opposite sides of the carrier that guide
the carrier and the in-circuit test fixture in a first
substantially horizontal direction; a vertical slider attached
between the carrier and the mechanism base comprising an actuator
that is operable to slide the carrier and the in-circuit test
fixture in a second substantially vertical direction between an
upper position and a lower position, wherein the horizontal slider
and the vertical slider are operable to guide the in-circuit test
fixture and the carrier between a receive position, wherein the
in-circuit test fixture may be loaded on the carrier, and a test
position, wherein a printed circuit board assembly supported by the
in-circuit test fixture may be tested; and a clamp mounted on a
testing base operable to selectively secure the in-circuit test
fixture to the testing base in the test position.
2. The loader of claim 1, wherein the actuator comprises a ram
connected to the carrier.
3. The loader of claim 1, further comprising a proximity sensor
mounted on the testing base and sensing whether the in-circuit test
fixture is in the test position.
4. The loader of claim 1, wherein the carrier further comprises a
pair of tracks, one of the tracks extending along each of the side
rails.
5. The loader of claim 4, wherein the carrier further comprises
rollers positioned along the tracks, the rollers being operable to
support the in-circuit test fixture and to aid sliding movement of
the in-circuit test fixture along the tracks.
6. The loader of claim 1, wherein the carrier includes a handlebar
between the side rails.
7. The loader of claim 1, further comprising a tray lock connected
to the mechanism base that selectively engages an aperture in the
carrier to lock the carrier in the receive position.
8. The loader of claim 1, wherein the clamp comprises a body and a
pair of arms extending from the body, the clamp moveable in a
spiral motion from an unclamp position, wherein the clamp does not
clamp the in-circuit test fixture, to a clamp position, wherein the
clamp clamps the in-circuit test fixture to the testing base in the
test position.
9. The loader of claim 8, further comprising a clamp actuator
connected to the testing base that is operable to move the clamp
spirally between the unclamp position and the clamp position.
10. The loader of claim 9, wherein the clamp actuator comprises a
ram connected to the clamp.
11. The loader of claim 10, wherein the ram extends through a plate
that is fixed to the base and wherein the clamp holds the
in-circuit test fixture between the clamp arms and the support
plate in the clamp position.
12. A method of loading an in-circuit test fixture in an in-circuit
test system, the method comprising: sliding the in-circuit test
fixture between side rails of a carrier until the in-circuit test
fixture abuts and end rail of the carrier when the carrier is in a
receive position; locking the in-circuit test fixture to the
carrier by preventing the in-circuit test fixture from moving away
from the end rail; sliding the carrier and the in-circuit test
fixture along horizontal guide shafts in a first horizontal
direction from the receive position to a match position; actuating
a vertical slider connected to the carrier to slide the in-circuit
test fixture along vertical guide shafts in a second vertical
direction from the match position to a test position; and clamping
the in-circuit test fixture in the test position.
13. The method of claim 12, wherein the actuating a vertical slider
step comprises actuating a ram.
14. The method of claim 12, further comprising a step of: sensing
that the in-circuit test fixture is in the test position before the
step of clamping the in-circuit test fixture in the test
position.
15. The method of claim 12, wherein the horizontal sliding step
comprises manually sliding the carrier.
16. The method of claim 12, wherein the clamping step comprises
moving a clamp in a spiral motion so that the clamp abuts the
in-circuit test fixture.
17. The method of claim 12, wherein the clamping step comprises
actuating a ram.
18. An in-circuit test fixture loader, the loader comprising: a
carrier operable to receive and support an in-circuit test fixture
so that the in-circuit test fixture is positioned between opposing
side rails of the carrier and the in-circuit test fixture abuts an
end rail of the carrier that extends between the side rails; and
means for sliding the carrier and the in-circuit test fixture
between a receive position, wherein the in-circuit test fixture may
be loaded on the carrier and unloaded from the carrier, and a test
position, wherein a circuit secured to the in-circuit test fixture
may be tested, and for selectively locking the in-circuit test
fixture in the test position.
19. The loader of claim 18, wherein the means for sliding and
locking comprises a mechanism connecting the carrier to a base, the
mechanism being operable to move the carrier relative to the base
between the receive position and the test position.
20. The loader of claim 19, wherein the mechanism comprises: a
horizontal slider that allows the carrier to move substantially
horizontally; and a vertical slider that allows the carrier to move
substantially vertically.
21. The loader of claim 18, wherein the carrier is a tray that
further comprises tracks extending along the side rails and
carrying rollers that are operable to support the in-circuit test
fixture.
Description
RELATED APPLICATIONS
[0001] This application claims priority of U.S. provisional
application Serial No. 60/364,775, filed Mar. 15, 2002.
FIELD OF THE INVENTION
[0002] This application relates generally to in-circuit testing and
more particularly to an in-circuit test fixture loader.
BACKGROUND OF THE INVENTION
[0003] Testing of disc drive printed circuit board assemblies is
done to ascertain the operational integrity of the circuit board
components. For in-circuit test systems, an in-circuit test fixture
supports the printed circuit board being tested. Additionally, the
fixture serves as an electrical and/or mechanical interface between
the circuit board assembly testing nodes and the required test
instruments.
[0004] Automated in-circuit test systems have been developed to
more efficiently test printed circuit board assemblies. However,
even in automated systems the fixtures have typically been manually
loaded into the test system. Such fixtures can be difficult to load
into the system, especially in "horizontal receiver access" test
systems where the fixture must be inserted horizontally through an
opening in the test system.
[0005] As an example, in one test system for testing disc drive
printed circuit board assemblies, the fixture includes separable
base plate and top plate assemblies, weighing about 18 kg and 10
kg, respectively. The base plate assembly of the system is
especially difficult to load. Factors contributing to this
difficulty include: (1) the weight of the base assembly (about 18
kg); (2) the structure of the base assembly (offset and elongated),
(3) limited access for gripping the assembly by hand; (4) awkward
loading position that is partially blocked by structural members of
the test system; and (5) the fixture wiring, which typically
includes more than 1000 wire connections. Loading such a fixture
into the test system can result in the base plate assembly
impacting portions of the testing system structure, which in turn
results in damage to the base assembly, wiring damage, or possibly
even injury to the operator.
[0006] Accordingly there is a need for a safer and more reliable
way to load fixtures for automated in-circuit test systems. The
present invention provides a solution to this and other problems,
and offers other advantages over the prior art.
SUMMARY OF THE INVENTION
[0007] Against this backdrop the present invention has been
developed. An in-circuit test fixture loader according to an
embodiment of the present invention includes a carrier that is able
to receive and support an in-circuit test fixture. The carrier
includes a pair of opposing side rails and an end rail between the
side rails. The side rails and the end rail are spaced to receive
the in-circuit test fixture between the side rails and against the
end rail. The loader also includes a fixture lock connected to the
carrier. The fixture lock is able to selectively abut the
in-circuit test fixture to prevent movement of the in-circuit test
fixture away from the end rail. A horizontal slider attached
between the carrier and a mechanism base includes guide shafts on
opposite sides of the carrier that guide the carrier and the
in-circuit test fixture in a first substantially horizontal
direction. A vertical slider of the loader is also attached between
the carrier and the mechanism base. The vertical slider includes an
actuator that is operable to slide the carrier and the in-circuit
test fixture in a second substantially vertical direction between
an upper position and a lower position. The horizontal slider and
the vertical slider are operable to guide the in-circuit test
fixture and the carrier between a receive position, wherein the
in-circuit test fixture may be loaded on the carrier, and a test
position, wherein a printed circuit board assembly supported by the
in-circuit test fixture may be tested. Also, a clamp mounted on a
testing base is able to selectively secure the in-circuit test
fixture to the testing base in the test position.
[0008] A method of loading an in-circuit test fixture in an
in-circuit test system according to an embodiment of the present
invention includes sliding the in-circuit test fixture between side
rails of a carrier until the in-circuit test fixture abuts and end
rail of the carrier when the carrier is in a receive position, and
locking the in-circuit test fixture to the carrier by preventing
the in-circuit test fixture from moving away from the end rail. The
method further includes sliding the carrier and the in-circuit test
fixture along horizontal guide shafts in a first horizontal
direction from the receive position to a match position, and
actuating a vertical slider connected to the carrier to slide the
in-circuit test fixture along vertical guide shafts in a second
vertical direction from the match position to a test position.
Finally, the method includes clamping the in-circuit test fixture
in the test position.
[0009] These and various other features as well as advantages which
characterize the present invention will be apparent from a reading
of the following detailed description and a review of the
associated drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a plan view of a disc drive showing the primary
internal components.
[0011] FIG. 2 is a rear perspective view of an in-circuit test
fixture loader according to a preferred embodiment of the present
invention before the fixture is positioned on the loader.
[0012] FIG. 3 is a separate perspective view of one side of the
horizontal slider shown in FIG. 2.
[0013] FIG. 4 is a separate perspective view of the vertical slider
shown in FIG. 2.
[0014] FIG. 5 is a separate perspective view of the clamp assembly
shown in FIG. 2.
[0015] FIG. 6 is a front perspective view of the loader of FIG. 2
with a fixture loaded in the test position showing the proximity
sensors in the loader.
[0016] FIG. 7 is a process flow chart of a method of fixture
loading according to a preferred embodiment of the present
invention.
[0017] FIG. 8 is a rear perspective view of the loader of FIG. 2
with the fixture positioned on the tray in the receive position and
the fixture locks in the unlock position.
[0018] FIG. 9 is a rear perspective view of the loader of FIG. 2
with the fixture positioned on the tray in the receive position and
the fixture locks in the lock position.
[0019] FIG. 10 is a rear perspective view of the loader of FIG. 2
with the fixture in the match position.
[0020] FIG. 11 is a rear perspective view of the loader of FIG. 2
with the fixture clamped in the test position.
DETAILED DESCRIPTION
[0021] A disc drive 100 constructed in accordance with a preferred
embodiment of the present invention is shown in FIG. 1. The disc
drive 100 includes a base 102 to which various components of the
disc drive 100 are mounted. A top cover 104, shown partially cut
away, cooperates with the base 102 to form an internal, sealed
environment for the disc drive in a conventional manner. The
components include a spindle motor 106, which rotates one or more
discs 108 at a constant high speed. Information is written to and
read from tracks on the discs 108 through the use of an actuator
assembly 110, which rotates during a seek operation about a bearing
shaft assembly 112 positioned adjacent the discs 108. The actuator
assembly 110 includes a plurality of actuator arms 114 which extend
towards the discs 108, with one or more flexures 116 extending from
each of the actuator arms 114. Mounted at the distal end of each of
the flexures 116 is a head 118, which includes an air bearing
slider, enabling the head 118 to fly in close proximity above the
corresponding surface of the associated disc 108.
[0022] During a seek operation, the track position of the heads 118
is controlled through the use of a voice coil motor 124, which
typically includes a coil 126 attached to the actuator assembly
110, as well as one or more permanent magnets 128 which establish a
magnetic field in which the coil 126 is immersed. The controlled
application of current to the coil 126 causes magnetic interaction
between the permanent magnets 128 and the coil 126 so that the coil
126 moves in accordance with the well-known Lorentz relationship.
As the coil 126 moves, the actuator assembly 110 pivots about the
bearing shaft assembly 112, and the heads 118 are caused to move
across the surfaces of the discs 108.
[0023] The spindle motor 106 is typically de-energized when the
disc drive 100 is not in use for extended periods of time. The
heads 118 are moved over park zones 120 near the inner diameter of
the discs 108 when the drive motor is de-energized. The heads 118
are secured over the park zones 120 through the use of an actuator
latch arrangement, which prevents inadvertent rotation of the
actuator assembly 110 when the heads are parked.
[0024] A flex assembly 130 provides the requisite electrical
connection paths for the actuator assembly 110 while allowing
pivotal movement of the actuator assembly 110 during operation. The
flex assembly includes a printed circuit board 132 to which head
wires (not shown) are connected; the head wires being routed along
the actuator arms 114 and the flexures 116 to the heads 118. The
printed circuit board 132 typically includes circuitry for
controlling the write currents applied to the heads 118 during a
write operation and a preamplifier for amplifying read signals
generated by the heads 118 during a read operation. The flex
assembly terminates at a flex bracket 134 for communication through
the base deck 102 to a disc drive printed circuit board (not shown)
mounted to the bottom side of the disc drive 100.
[0025] Testing of disc drive printed circuit board assemblies is
done to ascertain the operational integrity of the circuit board
components. FIG. 2 illustrates a loader 210 for loading an
in-circuit test fixture 212 into an in-circuit test system. The
fixture 212 preferably supports a printed circuit board assembly to
be tested in the in-circuit test system. The loader 210 includes a
tray or carrier 214 and a mechanism 215 that facilitates movement
of the tray 214 in a horizontal direction and in a vertical
direction. More specifically, the mechanism 215 has a horizontal
slider assembly 216 that facilitates horizontal movement of the
tray 214, and a vertical slider or slider assembly 218 facilitates
vertical movement of the tray 214. The mechanism 215 is secured to
a loader base 220 that is attached to the remainder of the
in-circuit test system (not shown). A clamp assembly 222 is
attached to a testing base 224.
[0026] Basically, a user positions the fixture 212 on the tray 214.
The user then slides the tray 214 forward, as allowed by the
horizontal slider assembly 216, so that the fixture 212 is
positioned above the clamp assembly 222. The user then slides the
tray downward, preferably by activating an actuator of the vertical
slider assembly 218. The clamp assembly 222 then clamps the fixture
212 so that it is stationary relative to the testing base 224. The
fixture 212 is then fully loaded and a circuit board assembly or
another circuit unit within the fixture can be tested by the test
system.
[0027] When it is desirable to remove the fixture 212, such as when
a manufacturing line has completed testing of a required number of
printed circuit board assemblies, the clamp assembly 222 releases
the fixture 212. The tray 214 and the fixture 212 are then moved
up, preferably via actuation of an actuator of the vertical slider
assembly 218. The tray 214 and the fixture 212 are then slid
backward, as allowed by the horizontal slider assembly 216. The
fixture 212 is then removed from the tray 214. Thus, the loader 210
allows a user to load and unload the fixture 212 without requiring
the user to support the weight of the fixture 212 while moving the
fixture 212 forward and down into the in-circuit test system.
[0028] The loader 210 will now be described in more detail with
reference to FIG. 2. The in-circuit test fixture 212, which is
illustrated in simplified form, may be an entire in-circuit test
fixture or only a part of the in-circuit test fixture, such as a
base plate assembly or a top plate assembly of an in-circuit test
fixture. The fixture 212 includes a body 230, which is illustrated
as substantially rectangular in shape. In the case of disc drive
printed circuit board testing, for example, the fixture 212 may
simply be represented as a box-shaped housing receiving and
supporting a disc drive circuit board assembly so that the disc
drive printed circuit board is exposed to the testing system. The
body 230 includes a bottom surface 232 and an opposing top surface
234. Fixture ears or plates 236 extend along opposing sides of the
body 230. Each ear 236 defines a pair of clamp receiving holes 238,
with one clamp-receiving hole 238 extending vertically through the
front portion of each ear 236 and one clamp-receiving hole 238
extending vertically through the rear portion of each ear 236.
[0029] The tray 214 includes a pair of side rails 250 that extend
backward from opposing ends of a front or end rail 252. Tracks 254
extend inwardly from the lower edge of each side rail 250 so that
each side rail 250 and track 254 forms a substantially L-shaped
cross section. Rollers 256 extend inwardly from each side rail 250
along an upwardly facing surface of each track 254. In a preferred
embodiment of the present invention, the rollers 256 each protrude
about 0.5 mm above the upper surface of each track 254 and are
spaced at about 30 mm intervals along each track 254. The rear of
each side rail 250 is raised and defines mounting holes 258
therein.
[0030] A handlebar 262, which is preferably an elongate plate,
extends between the bottom rear of each track 254. The handlebar
262 defines a pair of gripping holes 264. Each hole 264 is
preferably sized and shaped to receive an average size set of human
fingers.
[0031] Referring now to FIGS. 2-3, the horizontal slider assembly
216 includes a pair of carriages 270 on opposite sides of the tray
214. Each carriage 270 has a substantially rectangular shaped body
272 that defines a pair of guide shaft holes 274 that extend
horizontally through the body 272, and a set of mounting holes 276
that extend normal to the guide shaft holes 274 and into the body
272. The mounting holes 276 of each carriage 270 align with the
mounting holes 258 in the tray 214 and receive fasteners, such as
screws that secure the tray 214 to the carriages 270.
[0032] Each carriage 270 also includes a pair of carriage ears 278
that extend up from the front and rear of the carriage body 272.
Each ear 278 has a fixture lock hole 294 therethrough that is
substantially parallel to the guide shaft holes 274. A flip-over
fixture lock 296 is seated between each set of carriage ears 278
and a pin (not shown) extends through the fixture lock holes 294
and through the fixture lock 296. Each fixture lock 296 is
preferably an elongate member that extends away from the carriage
270. The fixture locks 296 can rotate about the pin between an
unlock position shown in FIGS. 2 and 8, where the fixture locks 296
extend outwardly from the carriages 270, and a lock position shown
in FIGS. 9-11, where the fixture locks extend inwardly from the
carriages 270. The fixture locks 296 are preferably held in each
position by gravity or may be spring biased in each of the unlocked
and locked positions.
[0033] Each side of the horizontal slider assembly 216 has a side
frame member 280 outwardly from the carriages 270 as shown in FIG.
3. The horizontal slider frame members 280 are substantially
parallel to the side rails 250 of the tray 214, but are on opposite
sides of the carriages 270 so that each carriage 270 is positioned
between a horizontal slider frame member 280 and a side rail 250 of
the tray 214. A horizontal slider support plate 282 extends between
the bottom of the horizontal slider frame members 280 and fixes the
horizontal frame members 280 together (see FIGS. 10-11). Two
support walls 284 extend inwardly at right angles from the ends of
each slider frame member 280. A lower and an upper guide shaft 286
extend along the frame members 280 between each set of support
walls 284. Each guide shaft 286 extends through a guide shaft hole
274 in a carriage 270 and supports the carriage 270 for sliding
movement forward and backward along the guide shafts 286.
Preferably, the carriages 270 include linear bearings that allow
the carriages to easily slide along the guide shafts 286. In a
preferred embodiment, the carriages 270 each include DU Bearings
available under part number NB-1625DU from Daido Metal Co. Ltd. of
Nagoya, Japan.
[0034] Two spring loaded tray locks 298, shown in FIG. 2, are
seated in the horizontal slider support plate 282 inwardly from the
rear support walls 284. The tray locks 298 preferably include
plungers or pins 299 that are spring loaded so that they are biased
upwardly through the horizontal slider support plate 282. The
plungers 299 preferably each include a step that they can move
upwardly when in one angular position, but not in another angular
position. When the tray 214 is located in its rear-most or
"receive" position as shown in FIG. 2 and the plungers 299 are
rotated so that the steps on the plungers 299 align with arcuate
recesses in the tray locks 298, the plungers 299 move up to a lock
position engaging apertures (not shown) in the handlebar 262 of the
tray 214. When the plungers 299 are pulled down from the lock
position to a release position, the tray 214 is released and can
move forward. The plungers 299 can be secured in the unlock
position by rotating the plungers 299 so that the steps on the
plungers 299 no longer align with the arcuate recesses in the tray
locks 298. Exemplary tray locks are available under part number
MIPL-NDX10LW from Imao Corp. of Gifu, Japan.
[0035] FIGS. 2 and 4 illustrate the vertical slider assembly 218,
which is separately shown in FIG. 4. The vertical slider assembly
218 includes a flat, generally U-shaped vertical slider support
plate 310 that is part of the mechanism base 220. A pneumatic
actuator 312 is secured to each leg of the U-shaped vertical slider
support plate 310. Each pneumatic actuator 312 includes a plunger
or ram 314 that extends upwardly through the vertical slider
support plate 310. The terminus of each ram 314 is secured to a
support bar 315 (FIG. 2) that is fixed to the outer side of one of
the frame members 280 of the horizontal slider assembly 216. Two
guide/alignment shafts 316 extend through the vertical slider
support plate 310 toward upper ends that are also secured to the
support bars 315 forward and rearward of the ram 314. Each pair of
alignment shafts 316 also extends down through the vertical slider
support plate 310 to an alignment shaft support bar 318. In this
way, alignment shafts 316 are maintained in parallel alignment
between the bars 315 and 318. Additionally, referring to FIG. 2, an
alignment shaft support unit 320 includes an L-shaped body 322 that
is fixed to the mechanism base 220 and to the front alignment shaft
316.
[0036] Referring now to FIGS. 2 and 5, each fixture clamp assembly
222 includes an L-shaped fixture support bracket 340 that has a
vertical plate portion 342 and a horizontal plate portion 344
extending inwardly from the top of the vertical plate portion 342.
The support brackets 340 are preferably rigidly mounted as part of
the testing base 244. Each horizontal plate portion 344 defines a
pair of clamp shaft holes 346 that align with the clamp receiving
holes 238 in the fixture 212 when the fixture 212 is positioned
over the clamp assembly 222 as shown in FIGS. 10-11. Each
horizontal plate portion 344 also defines an upwardly facing
fixture support surface 348.
[0037] The fixture clamp assembly 222 also includes a pair of
L-shaped clamp actuator support brackets 360 that are secured to
each vertical plate portion 342 below and parallel to the
horizontal plate portion 344. Each clamp actuator support bracket
360 defines a pair of actuator access holes 364 that are aligned
with the clamp shaft holes 346 through the horizontal plate portion
344. Two clamp actuators 366 are fastened to each clamp actuator
support bracket 360 and include rams 368 that extend upwardly
through the actuator access holes 364 and through the clamp shaft
holes 346 through the horizontal plate portion 344. The actuators
are preferably pneumatic cylindrical actuators, such as those
available under part number AC-MKA40-10TL from SMC Corp. of Tokyo,
Japan. The actuators 366 also each include an upper reed sensor 370
that senses when the corresponding ram 368 is in its upper-most, or
unclamped, position and a lower reed sensor 372 that senses when
the corresponding ram 368 is in its lower-most, or clamped,
position.
[0038] A clamp 380 is fixed to the upper end of each ram 368. Each
clamp 380 includes a cylindrical clamp body 382 seated on a ram 368
and a pair of clamp arms 384 that extend in opposite horizontal
directions from the top of the clamp body 382 and then curve
downwardly. The clamp actuators 366 each move the ram shafts, and
thus the clamps 380 in a spiral motion so that the clamp arms 384
rotate as to extend forwardly and rearward from the clamp body 382
when the rams 368 are in their uppermost or release position (see
FIG. 10) and the clamp arms 384 extend ninety degrees to the left
and right from the clamp body 382 when the rams 368 are in their
lowermost or clamp position (see FIG. 11).
[0039] FIG. 6 illustrates a pair of proximity sensors 390 that
extend upwardly and inwardly from the testing base 224 forward from
the clamp assembly 222. The proximity sensors 390 activate by
sensing the front of the fixture 212 when the fixture 212 is in the
match position shown in FIG. 10 or the loaded position shown in
FIG. 11. The proximity sensors 390 preferably sense whether the
proximity sensors are within about 1 mm of a metallic object. The
proximity sensors 390 may be 1 mm proximity switches sold under
part number ENP-ESE-X1C1 by Omron, of Kyoto, Japan.
[0040] The various structural components of the loader 210
discussed above are preferably secured together with fasteners,
such as screws or bolts. Also, the loader 210 is preferably
positioned about one meter above the floor, positioning the loader
210 ergonomically for human handling of a heavy item, such as the
in-circuit test fixture 212.
[0041] Use of the loader 210 will now be described with reference
to FIG. 7. A user first secures the tray 214 to the mechanism base
220 in lock tray operation 410 by rotating the plungers 299 of the
tray locks 298 so that the plungers 299 move up to engage the
apertures in the tray 214. The tray 214 is thus locked in the
receive position shown in FIG. 2.
[0042] The user then mounts the test fixture 212 onto the tray 214
and slides the in-circuit test fixture 212 along the rollers 256 of
the tray 214 in place fixture operation 412. Preferably, the
fixture 212 is slid until a front surface of the fixture 212 abuts
the end rail 252 of the tray 214, as shown in FIG. 8. The rollers
256 along the tracks 254 then support the fixture 212. The end rail
252 prevents the fixture 212 from sliding farther forward and the
side rails 250 prevent the fixture 212 from sliding to either
side.
[0043] In lock fixture operation 414, a user rotates the fixture
locks 296 180 degrees from the inward horizontal unlock position
shown in FIG. 8 to the opposite horizontal lock position shown in
FIG. 9. In the lock position of FIG. 9, the fixture locks 296
prevent the fixture 212 from sliding backward on the tray 214.
Thus, the combination of the side rails 250, the end rail 252, and
the fixture locks 296 secures the fixture 212 on the tray 214.
[0044] The user then pulls each of the plungers 299 down and
rotates them to secure them in the unlock position where they are
disengaged from the apertures in the tray 214 in unlock tray
operation 416. The tray 214 is then free to move forward, which
movement is facilitated by the horizontal slider 216. In slide
forward operation 420, the user slides the tray 214 and the fixture
212 forward along the rails 286 to the match position illustrated
in FIG. 10.
[0045] In match position query operation 422, it is determined
whether the fixture 212 is positioned so that the clamp receiving
holes 238 are aligned above the clamps 380. This is done by visual
inspection and by the proximity sensors 390, which sense whether
the fixture 212 is positioned fully forward in the proper match
position. In fact, the loader 210 preferably will not proceed to
lower the fixture 212 until the proximity sensors 390 detect a
fixture in the match position. This prevents the loader 210 from
undesirably proceeding if a fixture 212 is not properly positioned
on the tray 214 or the tray 214 has not been properly moved to the
match position. If the fixture 212 is not in the proper match
position, then the user preferably detects the problem and fixes it
in inspect and fix operation 424. If the fixture 212 is then in the
proper match position as determined in the match position query
operation 422, then the user can continue with a lower tray and
fixture operation 430.
[0046] In the lower tray and fixture operation 430, the user
preferably depresses a button or a pair of buttons to activate the
actuators 312 of the vertical slider assembly 218. The actuators
312 move the rams 314 of the vertical slider 218 and in turn move
the fixture 212 and the tray 214 down from the match position of
FIG. 10 to the test position of FIG. 11. Then, in clamp operation
432, the clamp actuators 366 draw the clamps 380 spirally
downwardly so that the clamps 380 secure the fixture ears 236
between the clamp arms 384 and the fixture support surfaces 348 of
the fixture support brackets 340.
[0047] In the test position query operation 434, the proximity
sensors determine whether the fixture 212 is properly seated fully
forward as is proper for the test position. Additionally, the lower
reed sensors 372 preferably sense whether the rams 368 are fully
retracted, and thus that the clamps 380 are in the clamped position
shown in FIG. 11. If the test position query operation 434
determines that the fixture 212 is not properly clamped in the
clamp position, then the user preferably detects the problem and
fixes it in inspect and fix operation 436. If the fixture 212 is
properly clamped in the test position as determined in the test
position query operation 434, then the fixture is ready for a
circuit or set of circuits, such as a set of circuits in a
component of a printed circuit board assembly to be tested. The
loader preferably illuminates an indicator light, such as a light
within one of the buttons discussed above, or otherwise signals
that the fixture is fully loaded and ready for testing. Preferably,
the in-circuit test system will not proceed with testing until the
test position query operation 434 determines that the fixture 212
is properly clamped in the test position. In test operation 440,
the in-circuit test system uses the fixture 212 in testing circuits
of circuit board assemblies.
[0048] A remove fixture query operation 441 determines whether it
is desirable to remove the fixture 212, for example when a
manufacturing line has completed testing of a required number of
printed circuit board assemblies or the fixture 212 must be removed
to perform repairs or maintenance. When it is desirable to remove
the fixtures 212, the fixture 212 is unclamped in unclamp operation
442. In unclamp operation 442, the clamp actuators 366 merely
reverse the motion of the clamp operation 432 described above. To
perform this operation, the user preferably depresses a button or
set of buttons to activate the clamp actuators 366. Alternatively,
the loader 210 can automatically unclamp the fixture 212 when
testing is complete. In raise tray and fixture operation 444, the
actuators 312 of the vertical slider 218 preferably lift the tray
212 and the fixture 214 to the match position shown in FIG. 10.
[0049] Once the raise tray and fixture operation 444 is complete,
the user grasps the gripping holes 264 of the handlebar 262 and
pulls the tray 212 and the fixture 214 backward to the receive
position shown in FIG. 9. The horizontal slider 216 facilitates
this movement. The user then rotates the plungers 299, allowing
them to be biased upwardly to engage the tray 214 in lock tray
operation 450. The user then pivots the fixture locks 296 from the
locked position shown in FIG. 9 to the unlocked position shown in
FIG. 8 during unlock fixture operation 452, freeing the fixture 212
to slide backward. The user pulls the fixture 212 out of the tray
214 along the rollers 256 in remove fixture operation 454.
[0050] An embodiment of the present invention may be summarized as
an in-circuit test fixture loader (such as 210). The loader
includes a carrier (such as 214) that is able to receive and
support an in-circuit test fixture (such as 212). The carrier
includes a pair of opposing side rails (such as 250) and an end
rail (such as 252) between the side rails. The side rails and the
end rail are spaced to receive the in-circuit test fixture between
the side rails and against the end rail. The loader also includes a
fixture lock (such as 296) connected to the carrier. The fixture
lock is able to selectively abut the in-circuit test fixture to
prevent movement of the in-circuit test fixture away from the end
rail. A horizontal slider (such as 216) attached between the
carrier and a mechanism base (such as 220) includes guide shafts
(such as 286) on opposite sides of the carrier that guide the
carrier and the in-circuit test fixture in a first substantially
horizontal direction. A vertical slider (such as 218) of the loader
is attached between the carrier and the mechanism base. The
vertical slider includes an actuator (such as 312) that is operable
to slide the carrier and the in-circuit test fixture in a second
substantially vertical direction between an upper position and a
lower position. The horizontal slider and the vertical slider are
operable to guide the in-circuit test fixture and the carrier
between a receive position, wherein the in-circuit test fixture may
be loaded on the carrier, and a test position, wherein a printed
circuit board assembly supported by the in-circuit test fixture may
be tested. Also, a clamp (such as 380) mounted on a testing base
(such as 224) is able to selectively secure the in-circuit test
fixture to the testing base in the test position.
[0051] The actuator may include a ram (such as 314) connected to
the carrier. Additionally, the loader may include a proximity
sensor (such as 390) mounted on the testing base and sensing
whether the in-circuit test fixture is in the test position.
[0052] The carrier preferably further includes a pair of tracks
(such as 254), with one of the tracks extending along each of the
side rails. Rollers (such as 256) may be positioned along the
tracks to support the in-circuit test fixture and to aid sliding
movement of the in-circuit test fixture along the tracks. The
carrier may also include a handlebar (such as 262) between the side
rails. The loader may also include a tray lock (such as 298)
connected to the mechanism base that selectively engages an
aperture in the carrier to lock the carrier in the receive
position.
[0053] The clamp preferably includes a body (such as 382) and a
pair of arms (such as 384) extending from the body. The clamp is
preferably moveable in a spiral motion from an unclamp position,
wherein the clamp does not clamp the in-circuit test fixture, to a
clamp position, wherein the clamp clamps the in-circuit test
fixture to the testing base in the test position. In a preferred
embodiment of the present invention, the loader includes a clamp
actuator (such as 366) connected to the testing base that is
operable to move the clamp spirally between the unclamp position
and the clamp position. The clamp actuator preferably includes a
ram (such as 368) connected to the clamp, and the ram preferably
extends through a plate (such as 344) that is fixed to the base.
The clamp holds the in-circuit test fixture between the clamp arms
and the support plate in the clamp position.
[0054] Stated another way, an embodiment of the present invention
may be described as a method of loading an in-circuit test fixture
(such as 212) in an in-circuit test system. The method includes
sliding the in-circuit test fixture between side rails (such as
250) of a carrier until the in-circuit test fixture abuts and end
rail (such as 252) of the carrier when the carrier is in a receive
position, and locking the in-circuit test fixture to the carrier by
preventing the in-circuit test fixture from moving away from the
end rail. The method further includes sliding the carrier and the
in-circuit test fixture horizontally along horizontal guide shafts
(such as 286) in a first horizontal direction from the receive
position to a match position, and actuating a vertical slider (such
as 218) connected to the carrier to slide the in-circuit test
fixture vertically along vertical guide shafts (such as 316) in a
second vertical direction from the match position to a test
position. Finally, the method includes clamping the in-circuit test
fixture in the test position.
[0055] The vertical slider step may include actuating a ram (such
as 314). Additionally, the method may include sensing that the
in-circuit test fixture is in the test position before the step of
clamping the in-circuit test fixture in the test position.
[0056] The horizontal sliding step preferably includes manually
sliding the carrier, and the clamping step preferably includes
moving a clamp (such as 380) in a spiral motion so that the clamp
abuts the in-circuit test fixture. The clamping step preferably
includes actuating a ram (such as 368).
[0057] Stated yet another way, an embodiment of the present
invention may be summarized as an in-circuit test fixture loader
(such as 210) that includes a carrier (such as 214), which is able
to receive and support an in-circuit test fixture so that the
fixture is positioned between opposing side rails (such as 250) of
the carrier and the fixture abuts an end rail (such as 252) of the
carrier that extends between the side rails. The loader also
includes means for sliding the carrier and the in-circuit test
fixture between a receive position, wherein the in-circuit test
fixture may be loaded on the carrier and unloaded from the carrier,
and a test position, wherein a circuit secured to the in-circuit
test fixture may be tested, and for selectively locking the
in-circuit test fixture in the test position.
[0058] It will be clear that the present invention is well adapted
to attain the ends and advantages mentioned as well as those
inherent therein. While a presently preferred embodiment has been
described for purposes of this disclosure, various changes and
modifications may be made which are well within the scope of the
present invention. For example, the horizontal slider 216 and the
vertical slider 218 could be arranged in a different configuration.
Numerous other changes may be made which will readily suggest
themselves to those skilled in the art and which are encompassed in
the spirit of the invention disclosed and as defined in the
appended claims.
* * * * *