‘Jan. 28,1969
`
`J. D. WILLIAMS
`DUAL PLUG-IN MODULE
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`Filed Oct. 19, 1966
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`3,425,025
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`84 E
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`JAMES D. WlLl-JAMS
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`BY
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`\0. W’
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`ATTORNEY
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`Apple 1060
`U.S. Pat. 9,189,437
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`

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`United States Patent 0
`
`3,425,025
`Patented Jan. 28, 1969
`
`1
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`3,425,025
`DUAL PLUG-IN MODULE
`James D. Williams, Colorado Springs, Colo., assignor to
`Hewlett-Packard Company, Palo Alto, Calif., a corpora
`tion of California
`Filed Oct. 19, 1966, Ser. No. 587,812
`5 Claims
`US. Cl. 339-75
`Int. Cl. H01r 13/54
`
`ABSTRACT OF THE DISCLOSURE
`A pair of mechanically separate and electrically related
`plug-in units are mechanically and electrically mated in
`side-by-side relationship to form a unitary plug-in mod
`ule for insertion into a single cavity of a main instrument.
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`10
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`15
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`This invention relates to mehanically separate but elec
`trically related plug-in units that are mechanically and
`electrically mated to form a dual plug-in module for in
`sertion into a high frequency instrument such as an os
`cilloscope.
`In order to increase the versatility of an oscilloscope
`system the horizontal and vertical deflection circuits for
`the cathode ray tube are often housed in separate hori
`zontal and vertical plug-in units, which may be mechan
`ically and electrically attached to and detached from the
`basic display instrument. It is then possible, for example,
`to substitute a delayed sweep horizontal plug-in unit for a
`standard sweep horizontal plug-in unit without also replac
`ing the vertical plug-in unit. Typically, these separate hori
`zontal and vertical plug-in units are each inserted into a
`separate cavity of the basic instrument and are each sepa
`rately attached mechanically and electrically to the basic
`instrument. This increases the hardware such as mechan
`ical guides and latches and electrical connectors required
`to mechanically and electrically attach the plug-in units
`to the basic instrument and therefore increases the cost
`of the oscilloscope system. Moreover, interconnecting
`circuitry between the plug-in units must be routed out the
`back end of one plug-in unit through a set of connectors,
`along signal transmission leads, and into the back end of
`the other plug-in unit through another set of connectors.
`These additional connections also increase the cost of the
`oscilloscope system and, in addition, increase the lead in
`ductance and capacitance and the contact potential as
`sociated with the interconnections between the plug-in
`units thereby increasing the signal loss during signal trans
`fer between the plug-in units.
`_
`Accordingly, it is the principal object of this invention
`to reduce the mechanical and electrical hardware required
`to mechanically and electrically attach a pair of mechan
`ically separate but electrically related plug-in units to a
`basic instrument and to make the required electrical inter
`connections between the plug-in units more direct so as to
`reduce the lead inductance and capacitance and the con
`tact potential associated withv these electrical intercon
`nections.
`This object is accomplished in accordance with the
`illustrated embodiment of this invention by providing a
`pair of plug-in units mechanically and electrically mating
`in side-by-side relationship so as to form a dual plug-in
`module for insertion into a single cavity of the basic in
`strument.
`Other and incidental objects of this invention will be
`apparent from a reading of this speci?cation and an in
`spection‘of the accompanying drawing in which:
`FIGURE 1 is a perspective view of a pair of mechan
`ically and electrically mating plug-in units according to
`the preferred embodiment of this invention;
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`2
`FIGURE 2 is a top view of the plug-in units of FIG
`URE 1 after they have been mechanically and electrically
`mated and inserted into the cavity of the basic instrument;
`and
`FIGURE 3 is a partially cut-away front view of the
`mechanically and electrically mated plug-in units of FIG
`URE 2.
`Referring now to the drawings, and particularly to
`FIGURE 1, there is shown a pair of mechanically sepa—
`rate but electrically related plug-in units 10 and .12 com
`prising, for example, the vertical and horizontal de?ec
`tion circuits of an oscilloscope system. A pair of keyhole
`slots 14 are formed in a side panel '16 of the plug-in unit
`10, and a latch member 18 is slidably mounted on an ad
`jacent side panel 20 of the plug-in unit 12. This latch
`member 18 may be mounted by forming a pair of narrow
`slots 22 in the side panel 20 of the plug-in unit 12, insert
`ing through each slot 22 the shank of a separate retaining
`bolt 19 having a circular head larger in diameter than the
`width of the slot 22, and fastening the shank of each re
`taining bolt 19 to the latch member 18 so as to restrict
`the latch member 18 to sliding movement between the
`opposite extremities of the slots 22. A pair of latch but
`tons 24 are ?xedly attached to the latch member 18 so
`that each latch button registers with the wide portion of
`a different one of the keyhole slots '14 when the latch
`member 18 is pulled out as shown in FIGURE 1. Each of
`these latch buttons 24 is adapted to ?t through the wide
`portion of the corresponding keyhole slot 14 and has a
`shank 25 that is adapted to ?t into the narrow portion
`of the corresponding keyhole slot 14 when the latch mem
`ber 18 is pushed in as shown in FIGURE 2. A front sub
`panel 26 of the plug-in unit 10 is provided with a pair of
`notches 28, and a front subpanel 30 of the plug-in unit
`12 is provided with a corresponding pair of tabs 32 that
`are adapted to ?t into and engage the notches 28 of the
`front subpanel 26 when the plug-in units 10 and 12 are
`mechanically mated. This arrangement of notches 28 and
`tabs 32 insures proper alignment of the front panels 34
`and 36 of the plug-in units .10 and 12 and prevents the
`front panels 34 and 36 from slipping, vertically, forward,
`or backward relative to one another since the notches 28
`and the tabs 32 have been engaged. The plug-in units 10
`and 12 are mechanically attached by pulling out the latch
`member 18 as shown in FIGURE 1 and as indicated by
`the dashed position of the latch member 18 shown in
`FIGURE 2, ?tting each latch button 24 through the wide
`portion of the corresponding keyhole slot 14, and en
`gaging the notches 28 and the tabs 32 of the front sub
`panels 26 and 30 as shown in FIGURE 3. The latch mem
`ber 18 is then pushed in as shown in FIGURE 2 so that
`the shank 25 of each latch button 24 ?ts into the narrow
`portion of the corresponding keyhole slot 14. This locks
`the plug~in units 10 and 12 together so as to form a dual
`plug-in module and prevents relative, motion between the
`plug-in units of this module. The hardware such as guides
`and latches required to insert this dual plug-in module
`into a single cavity of a basic instrument 37 is no greater
`than that normally required for a single plug~in unit.
`The plug-in units 10 and 12 are electrically mated to
`gether through a multi-terminal female connector 38
`mounted on the side panel 16 of the plug-in unit 10 and by
`a corresponding multi-terminal male connector 40
`mounted on the side panel 2%) of the plug-in unit 12. The
`male connector 40 is adapted for mating with the female
`connector 38 when the plug-in units 10 and 12 are me
`chanically locked together. This direct connection be
`tween the plug-in units 10 and 12 substantially reduces the
`length of the interconnecting leads conventionally used
`between the plug-in units 10 and 12 and therefore reduces
`the lead inductance and capacitance associated with these
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`3,425,025
`3
`4
`interconnecting leads. Thus, the loss of signal because of
`electrically and mechanically mates these side panels
`lead inductance and capacitance is substantially reduced.
`of the plug-in units together in said ?rst direction to
`Moreover7 since only one set of connectors is used the
`provide the unitary plug-in module, the plug-in units
`contact potential and hence the signal loss due to contact
`of said unitary plug-in module having their front
`potential is cut in half. The power for both plug-in units
`panels disposed in a common plane substantially nor
`10 and 12 is derived from the basic instrument 37 through
`mal to said second direction.
`a single connector 42 mounted on the back panel 44 of
`4. Plug-in apparatus as in claim 3 wherein:
`the plug-in unit 12. The plug-in unit 10 receives its power
`the electrical connector mounted on the side panel
`from the plug-in unit 12 and therefore need not be electri
`of one of said plug-in units comprises a female
`cally connected to the basic instrument 37. This feature in
`connector;
`combination with the direct connection between the plug
`the electrical connector mounted on the side panel
`in units 10 and 12 substantially reduces the number of
`of the other of said plug-in units comprises a male
`connectors required by the plug-in units.
`connector;
`I claim:
`one of said mechanical connectors comprises a pair of
`1. Plug-in apparatus for insertion into a single cavity of
`spaced keyhole slots in the side panel of one of the
`an electrical instrument, said apparatus comprising:
`plug-in units, each of said ‘keyhole slots having an
`A ?rst plug-in unit for the electrical instrument, said
`enlarged portion and a narrow portion; and
`?rst plug-in unit having an electrical connector and a
`the other of said mechanical connectors comprises a
`mechanical connector; and
`latch slidably mounted on the side panel of the other
`a mechanically separate second plug-in unit for the
`of the plug-in units, said latch being operable in one
`electrical instrument, said second plug-in unit having
`position for entering the enlarged portions of the
`an electrical connector releasably engageable with
`keyhole slots and then being slid to another position
`the electrical connector of the ?rst plug-in unit to pro
`for engaging the narrow portions of the keyhole slots
`vide an electrical signal conduction path between the
`to releasably mate the plug-in units together and pro
`plug-in units, said second plug-in unit also having a
`vide the unitary plug-in module.
`mechanical connector releasably engageable with the
`5. Plug-in apparatus as in claim 4 wherein:
`mechanical connector of the ?rst plug-in unit for re
`one of said plug-in units has a housing including the
`leasably mating the plug-in units together in a ?rst
`front and side panels of that plug-in unit and having
`direction to provide a unitary plug-in module for in
`a notch; and
`sertion into the cavity of the electrical instrument in
`the other of said plug-in units has a housing including
`a second direction substantially normal to said ?rst
`the front and side panels of that plug-in unit and
`direction;
`having a tab for engaging said notch when the plug
`at least one of said unitary plug-in module and said elec
`in units are electrically and mechanically mated to
`trical instrument including means for electrically
`gether thereby preventing relative movement of one
`connecting said unitary plug-in module and said elec
`plug-in unit with respect to the other in planes that
`trical instrument upon insertion of the unitary plug
`are parallel to said second direction.
`in module into the cavity of the electrical instrument.
`2. Plug-in apparatus as in claim 1 wherein said means
`comprises an additional electrical connector of at least one
`of the plug-in units, said additional electrical connector
`being operable for electrically engaging the electrical in
`strument upon insertion of the unitary plug-in module into
`the cavity of the electrical instrument in said second
`direction.
`3. Plug-in apparatus as in claim 2 wherein:
`said ?rst plug-in unit has a front panel and has a side
`panel including the electrical and mechanical con
`nectors of the \?rst plug-in unit; and
`said second plug-in unit has a front panel and has a
`side panel including the electrical and mechanical 50
`connectors of the second plug-in unit;
`whereby engagement of the electrical and mechanical
`connectors of the ?rst plug-in unit with the electrical
`and mechanical connectors of the second plug-in unit
`
`References Cited
`UNITED STATES PATENTS
`6/ 1936 Frank ____________ __ 339——185
`2,043,796
`9/1952 Lockhart __________ __ ‘339-75
`2,610,998
`5/1962 Todd ____________ __ 339———154
`3,034,000
`6/1966 MacKenzie et a1 _____ __ 339—19
`3,255,330
`3,345,599 10/1967 Henschen et al. _____ ___ 339—19
`2,229,150
`1/1941 Wadsworth ________ __ 339—~31
`2,265,341 12/1941 Borchert ___________ __ 339——76
`2,448,725
`9/ 1948 Morris ____________ __ 339-76
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`MARVIN A. CHAMPION, Primary Examiner.
`JOSEPH H. MCGLYNN, Assistant Examiner.
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`317-99; 339—1-86
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`US. Cl. X.R.