Note: Descriptions are shown in the official language in which they were submitted.
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This is a division of our Canadian Patent Application Serial No.
275,789 filed April 7, 1977.
This invention relates to a shock resistant mounting arrangement
for mounting an object in a casing.
Although many electronic circuits have been miniaturized to micro-
size, a continuing problem in micro-electronics is making the connections
between the micro-electronic components and other components which cannot
be miniaturized, such as displays and power supplies and in mounting objects
in a casing.
Seven segment display digits are widely used in digital displays
of electronic devices such as hand held calculators and digital readout
electronic test equipment, for example, volt meters and multimeters. Such
displays usually require seven conductor connections for each digit, and
additional conductors and connections are required for a floating decimal
point and com n return path, such as ground. Correspondingly, a three
; digit readout with floating decimal point will require on the order of
twenty-six electrical connections to the register or driver circuitry.
Disclosed herein is an apparatus and method including a conductor
array and contact arrangement which simplifies making electrical connections
between, for example, a circuit board and a display panel spaced from the
circuit board and which can be of the plug in type. A specific application
for this conductor-contact array is for connecting a register or display
driver circuit board to a digital readout panel such as a liquid crystal
display panel.
Correspondingly, in accordance with the disclosed method and
construction only a minimum number of parts and pieces is required for the
display panel, display holder, conductors and contacts, and the mounting of
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the display holder in a shock proof manner between the base and cover of the
instrument.
According to a broad aspect of the invention there is provided a
shock resisting mounting arrangement for mounting an object in a casing com-
prising, an object having a body to be mounted in a casing, and characteri~ed
by first and second stiff unitary arms extending from the body, each arm having
a plurality of fingers including at least two resilient fingers in a common
plane, and at least a third resilient finger between said at least two fingers
and in a plane spaced from the plane of said at least two fingers, said plural-
ity of fingers each being of substantial length to enhance its resiliency, and
cooperating clamp means on the casing for receiving the fingers of the respec-
tive arms therebetween, said clamp means including means for restraining said
arms against movement in the plane of said at least two fingers, and means for
clamping against said fingers to urge the plurality of fingers toward a common
;~ plane so that the body is resiliently mounted between the fing0rs of the
respective arms.
Numerous other objects, features and advantages of the invention
~ will become apparent with reference to the accompanying drawings which form
a part of this specification.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a partial side view in section showing a portion of an
; eleclronic instrument incorporating features of this invention;
Figure 2 is a plan view of a liquid crystal display panel used in
the instrument of Figure l;
Figure 3 is a plan view of a display panel holder with contacts and
display panel removed for clarity of illustration;
Figure 4 i5 a partial view in section taken along line 4-4 of
Figure 1, and showing the cover before it is fully seated on the base;
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Figure 5 is a pictorial view of a contact array used in the in-
strument;
Figure 6 is an enlarged pictorial view of the contact retaining
portion of the display holder of Figure 3;
Figure 7 is a view corresponding to Figure 6 and showing a contact
end in position in a recess of the display holder;
Figure 8 is a top plan view of the contact retaining portion of the
display holder as shown at Figure 7, with a contact end therein;
Figure 9 is a plan view of a portion of the circuit board of the
instrument of Pigure 1, showing its array of terminal openings;
Figure 10 is an enlarged side view in section taken along line
10-10 of Figure 9 and showing a conductor array positioned on the circuit
board;
Figures 11 and 12 are side views in section and show the sequence
of steps to connect the contact ends of the conductors to the display holder,
with Figure 11 showing the conductors threaded through the holder, and Figure
12 showing the contact ends seated in the holder; and
Figure 13 is a side view in section showing the manner in which in-
creased contact pressure is obtained by curving or tensioning the conductors.
Figure 1 shows a portion of an electronic instrument 10 which can
be a portable digital multimeter or digital voltmeter. Instrument 10 includes
a base casing 12 and a cover 14 which seats on and closes the casing. A cir-
cuit board 16 is secured near the bottom of casing 12, and multiple conductors
18 extend from the circuit board to a display holder or housing 20 having a
socket portion 22 in which contact ends 24 of the conductors are secured. A
display panel 26 is plugged into the socket portion so conductors on surface 28
of the panel engage and electrically connect to the contact ends 24 of con-
ductors 18. Display housing 20 has a transparent window 30 which is rec-
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tangular and through which the digits on the display face 32 of display panel
26 are visible. Top cover 14 is opaque, and has a rectangular opening 34
through which only the display face 32 of panel 26 can be seen, when the cover
is in position as shown at Figure 1.
Each conductor 18 has a terminal tip 36 which extends through an
opening in circuit board 16 and which is soldered to the circuit board prior
to mounting the circuit board in casing 12.
Figure 2 shows display panel 26 in greater detail. Such display
panel is preferably of the liquid crystal type, operating in the reflective
mode, and can include three seven segment digits, such as digits 40, several
decimal points, such as decimal point 42, a "l" digit 44 and a minus sign
46. The type of display, is of course exemplary and the display panel can
have any desired number of digits.
The various segments, decimal points, etc. within the body of dis-
play panel 26 are electrically connected to conductors 48 exposed on the rear
portion of the lower surface of the display panel (surface 28 of Figure 1).
Each of the conductors 48 is of the deposited type and is a fraction of a mil
thick, so the conductors within the body 49 of the display, are transparent,
and hence, not visible to one looking at the display through opening 34 of the
casing. As is apparent from Figure 2, display panel 26 has a total of 27
electrical conductors 48 exposed on its rear surface 28. The minutely thin
conductors 48 are subject to damage if abraded or scuffed.
As shown at Figures 3 and 4, display holder 20 takes the form of a
one piece part, of plastic material, and is preferably molded from a trans-
parent thermoplastic such as clear polycarbonate. Holder 20 has a generally
rectangular frame portion 50 which surrounds rectangular window 30, the rec-
tangular window projecting upwardly from this frame portion. Side walls 52
of the holder project rearwardly of frame portion 50 and have inside surfaces
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54 spaced apart a distance only slightly greater than the width of display
panel 26 as measured between its side edges 56. Correspondingly, the side
edges 56 of the display panel 26 cooperate with surfaces 54 to locate panel
26 in the holder~
Projecting inwardly from each side wall is a display panel retaining
lug 58 which is spaced from rear frame face 60 of the holder a distance
approximating the thickness of the display panel, as measured between its
front and rear surfaces 62, 63. Retaining lugs 58 prevent ~he display panel
from moving in a direction perpendicular to the plane of window 30. The
tracks formed by lugs 58, surfaces 54, and surface 60 serve to guide and
accurately position the display panel in the holder 20.
Extending outwardly and downwardly from side walls 52 of the dis-
play holder are mounting arms 64 which are slightly narrower than window 30.
As shown at Figure 3, each mounting arm 64 includes a pair of outer fingers
66 separated from a central finger 68, by slots 69, which extend a major por-
tion of the length of each arm. End portions 67 of each finger are parallel
to the plane of window 30. As shown at Figure 4, with the fingers relaxed,
the outer fingers 66 are in a common plane, and central finger 68 is above
the plane of the fingers 66 by a distance about one-half the thickness of the
fingers. Each of the fingers 66 and 68 is thus relatively narrow and
- resilient. These fingers and arms provide a shock proof means for unting
the display holder in the casing. The display holder can also have openings
70 or recesses 71 to receive positioning pins (not shown) which can be provid-
ed in the cover 14 to align the display holder with the cover.
As shown at Figures 1 and 4, cover 14 has a generally inverted U-
shaped recess 72, formed in the inside of each of its side walls 73, and
which opens downwardly. Recess 72 presents a downwardly facing shoulder 74
generally parallel to the plane of display window 30, when the display holder
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is mounted in the casing. Side edges 75 of the recess are perpendicular
to shoulder 74 and present a space to receive the fingers 66, 68 of the msunt-
ing arms 64. A projection of a width the same as recess 72 has a slot 78
and presents a pair of fingers 76, each of a width about the same as mount-
ing fingers 66 of the display holder. End edges 82 of the fingers are parallel
to shoulder 74. The cover and base are so dimensioned that the distance be-
tween shoulder 74, and the end edges 82 of fingers 76, when the cover is
secured to the base, approximates the thickness of mounting fingers 66 of
the display holder.
Figure 4 shows fingers 66 and the cover and base in position immedi-
ately before pressing the cover home on the base. The final closing motion
of the cover to seat on the base causes shoulder 74 to engage the top
surface of central finger 68 to resiliently press this finger downwardly into
the plane of the fingers 66. Such mounting of the display holder with the
fingers 66 and 68 tensioned, permits the display holder to move slightly with
respect to the casing as a result of the resiliency of the fingers 66, 68
and thus provides a shock proof mounting and securing arrangement which is
inexpensive, yet quite effective. Even if the space between shoulder 74
of recess 72 and end edges 82 of fingers 76 is greater than the thickness of
fingers 66, 68 sufficient clamping action is attained by virtue of the off-
set resilient fingers 66 and 68, to firmly hold the display holder in position.
The display holder 20 is solely supported by the arms 64.
The display holder, as shown at Figure 3, does not yet have the
contacts mounted thereon. The contact ends 24 of the conductors 18 are
; received in the region of socket 22. A mounting block 86 which is an
integral part of display holder 20 includes a continuous bar portion 88 which
extends between and is integral at each end with side walls 52. As can be
seen from Figure 1, this bar portion is somewhat below the plane of window
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30, and there is an open space 89 between bar portion 88 and lower edge 91
of frame 50, this space being continuously open between surfaces 54 of the
side walls. The bar portion has multiple recesses 90 between locating ribs
92. The contact ends 24 seat and lock in the recesses 90 in a manner soon
to be described. Recesses 90 are equal in number to the conductors 48 of
the display panel, and a contact end 24 of a conductor is received in each
recess. Where the display holder 20 is used with display panel 26, there are
twenty-seven such recesses 90.
Figure 5 shows a portion of a conductor-contact array 96, which
includes multiple conductors 18. As shown, there are conductor-contact ele-
ments 98, 100, 102 and 104. Each conductor-contact element has a thin re-
silient conductor body portion 106 substantially wider than its thickness.
This body portion is of uniform width and thickness along its length. At one
end of each conductor body is a terminal tip 108 which preferably has a pointed
end. The terminal tip is offset with respect to the plane of conductor body
106 by bending the tip to provide a shoulder 110 perpendicular to conductor
portion 106. Slightly inwardly of shoulder 108 is an enlargement which provides
a lateral extension 112, coplanar with body 106. The terminal tip ends of
conductor-contact elements 98, 100, 102 and 104 are connected together by a
bridging strip 114 with legs 116 projecting perpendicular to the conductors,
and joining the lateral extensions 112 at a location spaced inwardly of
sho~lders 110. Legs 116 are joined to the lateral extensions 112 along a
sharp crease or weakened line 118. As is apparent with reference to Figure
; 5, the length of legs 116 is sufficient that the terminal tip ends, legs
116, and bridging strip 114 of the several conductors can be formed from a
flat sheet of metal, by stamping, and the bridging strip 114 and legs 116
can then be bent upwardly to the position shown. The bridging strip 114~
joined to conductors 18 at a locat on very close to the terminal tips 108,
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accurately spaces the tips, and holds them rigid.
Contact ends 24 of each conductor include an enlarged body 120
having a centrally disposed struck out contact portion 122 with a rounded
contact nose 124. Contact 122 joins body 120 at a bend 126. Also cut from
body 120 is a lock tab 128 which is bent downwardly in a direction away from
contact 122. Lock tab 128 joins body 120 at bend 130. Between the bends 126,
and 130, the body takes the form of relatively narrow parallel legs 132. A
triangularly shaped latch finger 134 projects laterally outwardly from the
outside of each leg 132. The latch fingers each present a latch surface 136
which faces toward lock tab 128, the surfaces being coplanar and located be-
tween bend 126 and lock tab 128. A nose 138 of each contact end is integrally
joined with a bridging strip 140, which is coplanar with body 120 of the con-
tact ends, and is joined to each nose 136 along a weakened or scored line 142.
The contact array 96 can be formed from a flat sheet of uniform
thickenss of electrically conductive material with resilient characteristics,
such as phosphor bronze, by stamping and bending. Each of the multiple con-
ductors 18 is somewhat resilient in all directions. However, by virtue of
the width of each conductor body portion, such as conductor body 98, being
substantially greater than its thickness, these conductor portions are
relatively stiff laterally, in their common plane, but are quite resilient
in a direction normal to this common plane. Legs 132 of contact body 120,
while relatively stiff, exhibit some lateral resiliency. Latch fingers
134 are located on legs 132 along portions of the legs which exhibit such
lateral resiliency. As will soon be described, latch fingers 134 and lock
tabs 128 provide for snap locking contact ends 24 in the respective recesses
j 90 of the display holder. I~hile conductor array 96 is illustrated with only
' four conductors 18, the array can, of course, have any number of conductors
; for example, twenty-seven.
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Figure 6 pictorially shows a portion of the contact holder support
bar 88 and illustrates the recesses 90 in greater detail. As shown at
Figure 6, a face 150 of support bar 88 forms the bottom of each recess 90.
A rib 152 projects perpendicular to surface 150, and side faces 154 of this
rib define the sides of the recess. Each rib has a laterally enlarged up-
wardly projecting forward end 156 which presents a sharp corner 158 diagonally
opposed to the corner formed by surfaces 150 and 160 of bar 88. Each side
wall 154 of rib 152 has a recess 162 which presents a lock surface 164. A
rear surface 166 of bar 88 slopes with respect to surface 150 to provide
an edge 168 in the plane of surfaces 164. The rear of each rib has a laterally
enlarged end 170 which presents a retaining surface 172 that is spaced from
and faces toward surface 166.
. Each laterally enlarged forward end 156 has a surface 174, the sur-
faces of the several ends 156 being coplanar. Surfaces 174 act as a stop
to limit the depth of insertion of display panel 26 into the holder. Sur-
faces 178 of the top of each rib from enlarged rearward end 170 to surface
174 are flat-and coplanar and are parallel with surface 28 of display panel,
26, when the panel is in the holder 20, as shown at Figure 1.
Figures 7 and 8 show portions of the display holder support bar 88
with a contact end 24 in position in a recess 90. It can be seen from Figures
7 and 8, that the distance between side faces 180 of enlarged forward ends
156, as well as the distance between the side faces 182 of enlarged rearward
ends 170 is slightly greater than the width of contact 124, and is greater
than the width of conductor body 106. Gn the other hand, body 120 of the con-
tact end is of a width approximating the distance between side faces 154 of
the recesses 90, and the body is beneath retaining surfaces 172 of the enlarg-
ed rearward ends 170, and is also beneath edges 158 of the enlarged forward
ends 156. Lock tab 128 engages lock surface 160 -of bar 88 to prevent
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displacement of a contact end rearwardly, and latch surfaces 136 of latch
fingers 134 engage surfaces 164 of recesses 162 to prevent pulling the contact
ends in a forward direction from the display holder socket. Since surfaces
172 and edges 158 of the forward and rearward enlarged ends extend across the
body 120 and legs 136 of the contact end, a contact end cannot be lifted from
the recess 90 after it is positioned in a recess as shown at Figures 7 and
8. With the contact end disposed in a recess~ it will be observed that edge
168 of bar 88 is generally aligned with latch edges 136 of the contact end,
and the edge 168 is beneath the flexible or resilient legs 132. In addition,
edge 158 extends over the body portion of a contact end near bend 130. With
the conductor body 106 of each conductor-contact relaxed, the contact ends
are relatively loose fits in the recesses, but are held against removal by
the latch fingers and latch tabs. In this relaxed position of the conductor
body 106, contact 122 has its contact point 124 only slightly above surface
178 of a rib so there is a very low contact pressure on the fragile conduct-
ors 48 of the display panel. It is in this relaxed condition of the con-
ductor-contact elements that the display panel 26 is inserted into the holder
20. Then, when the conductor bodies are curved, as shown at Figure 1, the
contacts 122 are elevated and are further pressed against the conductors 48
of the display panel. When a conductor body 106 is bent downwardly, the front
of a contact end is lifted into engagement with edge 158, and legs 132 tend
to rlex or bow upwardly as a result of engagement with edge 168. This causes
contact 122 to move upwardly and correspondingly increases the contact pres-
sure between nose 124 and a conductor 48 on the rear surface 28 of display
panel 26. The bowed or higher pressure condition of the contacts is shown
at Figure 13.
This arrangement, permits inserting the display panel 26 into holder
20, when the contact pressure is very low, so damage to the conductors 48
is avoided as a result of the sliding movement of the contacts 122 on the con-
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ductors during such insertion. However, the contact pressure created when
the conductor bodies are curbed or tensioned, provides good electrical con-
tact between the contacts 122 and the conductors 48 of the display panel.
METHOD OF ASSEMBLY
A preferred method of assembling electronic instrument 10 will now
be described. As shown at Figure 9, circuit board 16 has mounted thereon,
electrical components such as resistors 188 having leads which extend through
openings of the circuit board and through openings in printed or foil con-
` ductors (not shown) on the lower surface of the board. At one end of the
board are a plurality of spaced apart terminal tip receiving apertures 192which extend in a line parallel to edge 194 of the board. Apertures 192
are spaced apart the same distance as the spacing of terminal tips 108
of conductor array 96 (Figure 5), by bridging strip 114.
~ Prior to soldering the leads of the components on the circuit board
; 16 to the circuit board conductors, a conductor array 96 is selected which
has 27 conductors. The terminal tips 108 are aligned with and stabbed through
openings 192 of the circuit board simultaneously, to the position shown at
Figure 10. At this stage of assembly, bridging strips 114 and 140 remain
connected to the conductor array. As a result, the conductor array is relat-
ively rigid and easy to handle, and stabbing the terminal tips 108 through
the apertures of the circuit board can quickly be accomplished. The depth
of insertion of the terminal tips 108 is limited by engagement of shoulders
110 with the top surface 196 of the board. It is preferred that the terminal
tips be inserted in the board prior to soldering the leads of the other com-
ponents such as resistors 188 to the board. Such soldering can be accomplish-
ed by dipping to simultaneously solder the component leads as well as all
terminal tips 108 to the board. After the terminal tips are soldered, bridg-
ing strip 114 can be broken away by flexing the strip in the direction of
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arrows 198 to break the bridging strip at the weakened lines 118 ~Figure 5
between the bridge legs 116 and lateral extensions 112. At this stage
of assembly, multiple conductors 18 project perpendicularly with respect to
the circuit board 16 but still form a relatively stiff assembly by virtue of
the bridging strip 140 which is still secured to their contact ends. By vir-
tue of this second bridging strip 140, the circuit board can be handled quite
easily without danger of in any way damaging the individual conductors or
contacts of the conductor array.
The next step is the mounting of contact ends 24 in the recesses
of socket portion 22 of the display panel holder. Such mounting is accomplish-
ed quite readily in accordance with the invention. As previously described
with reference to Figure 3, there is an unobstructed opening 89 between edge
91 of the display holder frame 50, and contact support bar assembly 86 of the
display holder. Bridging strip 140 of the contact array is passed through
this opening from behind the display window 30, and the display holder is
then moved toward the circuit board until the contact bodies 120 are beyond
the recesses, and the conductor bodies 106 are opposed to the recesses.
The conductor bodies can then be moved into the recesses beneath the level of
edges 158 and surfaces 178 of the respective laterally enlarged ends of a
recess, as shown at Figures 6 and 11. This can be done because each conductor
body 106 has a width slightly less then the distance between the side surfaces
180 and 182 respectively of these ends ~see Figure 8). Then, the contact
holder is pulled toward the bridging strip 140, or alternately the strip is
pushed toward the contact holder (see Figures 1 and 8) which causes body 120
of each contact end to pass under edge 158 until the latch fingers 136 (Figure
5) enter the region between side surfaces 154 of the recess. By virtue of
the resiliency of legs 132 of the contact end body 120 (see Figure 5) the
latch fingers flex inwardly as the contact body is pulled through the recess.
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Ultimately, the then compressed latch fingers 136 pass beyond lock shoulders
164 and snap outwardly ~see Figures 7 and 8). Lock tab 128 of a contact body
engages surface 160 of a socket recess to prevent pulling the contact body
out of the recess in a direction toward its terminal tip ends, and latch
fingers 136 lock behind shoulders 168 to prevent pulling the contact ends
out of the socket in the opposite direction. Figures 8 and 12 show the
display holder with the contacts seated therein.
With the contact ends so secured in the display holder, the bridg-
ing strip 140 (Figure 13) is b,rnken off by bending along the weakened lines
10 142. The display panel is then inserted into the holder while the multiple
conductors are straight and perpendicular to the circuit board. Insertion
of the display panel while the conductors are straight provides for insertion
of the panel while there is very low contact pressure between contacts 122
and the fragile conductors 48 of the display panel.
Next, the circuit board is mounted in base casing 12 and secured
in any suitable manner, for example, with screws. The display holder is then
turned from the position of Figure 12 about an axis parallel to cirucit board
16 and the plane of the width of the conductors so the display holder window
30 is generally parallel with the circuit board. In this position, cover
20 14is moved over the display holder, mounting arms 64 of the display holder
are aligned with recess 72, and the cover is pressed down into a seated posi-
tion on base casing 12. During such final closing, resilient mounting fingers
~ 66 and 68 are clamping between the cover and base, as previously described,
$ to provide a shock proof mounting for the display holder. The cover is then
secured to the base for example, with screws and the assembly is complete.
As shown at Figures 1 and 4 there is a space 200 between display win-
dow 30 and the r0ctangular opening 34 of cover 14. This space shows that
the display holder is held only by the arms 64 which are clamped at their ends
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between base 12 and cover 14. By virtue of the resiliency of the ends of
the arms, the display holder is firmly held, but can move to absorb shock and
impact which might normally damage the delicate display panel 26.
During such final assembly, where the display holder is rotated
from the position of Figure 12, to the position of Figures 1 and 13, multiple
conductors 18 become curved and cause contacts 122 to extend and exert higher
contact pressure against the deposited conductors of the display panel, there-
by assuring good electrical contact in the final assembly position. As
shown at Figure 13, contact end body 120 becomes bowed upwardly as a result
of engagement with edges 158 and 168, as the conductor body is curved down-
wardly. Such bowing of the contact end body causes the contact 122 to
tilt upwardly, thereby increasing the contact pressure. The relaxed position
of the conductors and contact ends is shown in dotted lines in Figure 13, and
the bowed condition is shown in solid lines.
It will be observed from Figure 1 that a stop rib 208 projects down-
wardly from cover 14 to a location closely adjacent edge 210 of display
panel 26. This rib prevents the display panel from sliding out of the mounted
` display holder.
While a preferred method of assembly has been described, it will
of course be apparent that terminal tips 108 need not be soldered to the
circuit board simultaneously by dipping, but can be hand soldered to the cir-
cuit board individually preferably prior to removing the bridging strip.
The conductor array 96 can thus be used for assembling electrical and
electronic apparatus from kit form, by the hobbyist.
Where additional electrical connections are to be made to circuit
board 16 after the circuit board is mounted in casing 12, display panel 26
can be inserted into the display holder after mounting the circuit board but
before orienting the display holder in its mounting position of Figure 1.
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While a preferred embodiment of contact array, display holder, andmethod of assembly have been shown and described, it is of course apparent
that numerous chan~es and variations can be made without departing from the
intended scope of this invention as set forth herein and in the appended claims.
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