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Патент USA US2099204

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Nov. 16, 1937.-
L. HAMMOND
2,099,204
MULTIPLE KEY SWITCH
Filed April 24, 1936
WW y»
5 sheets-sheet 1 `
@dat
MULTIPLE KEY SWITCH
Filed April 24, 1956
Z@
/z £25
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3 Sheets-Sheet 2
NOV. 16, 1937. `
‘L_ HAMMOND
MULTIPLE KEY SWITCH-
2,099,204
@attentati New. lr6, 'w37
ATENE”
ia; Ü STATES
esta
2,099,294
MULTIPLE KEY SWITCH
Laurens Hammond, Chicago, m.
l Application April 2i, 1936, Serial No. 76,157
19 Glaims.
(Cl. SQL-337)
My invention relates generaily to multiple key
switches, and more particulariy to switches us
able in electrical musical instruments.
It is an object of my invention to provide an
various parts used with, but not directly con
ce1-ned with7 the invention claimed herein.
As more fully disclosed in the aforesaid patent,
alternating sine wave currents of the various fre
e improved multiple key switch which is simple and
durable in construction, which may be easily
assembled, and in which the contact points may
be easily cleaned.
duced by minute generators, and by means of
key-operated switches, current from selected ones
of Athese generators, corresponding to the funda
A further object of my invention is to provide
a multiple switch assembly in which all of the
parts are contained in a dust-proof housing.
A further object is to provide an improved
method of wiring the terminals of the switches '
to soldering lugs.
mental and the various desired harmonics, are,
upon the depression of a key, simultaneouslyin- 10
troduced into the output circuit of the instru
ment. Inasmuch as the instrument may have
sixty-one keys for each manual, and each ,key
will operate nine switches, it will be apparent
'
vided. These switches are preferably arranged
in iìles spaced apart by the distance between the
in their supports without the use of tools of any
successive keys of the standard organ manual, in
kind.
order that the actuation oi' the switches by the
keys may be readily accomplished. For this 20
reason, the usual contact switch construction
'
Other objects will'appear from the following
description, reference being had to the accom
panying drawings, in which:
Fig. 1 is a vertical cross-sectional view of the
manual and key-operated switch assembly of
an electric organ;
l
Fig. 2 is an enlarged fragmentary section taken
on the line 2_2 of Fig. l, one of the multiple
key switches being shown in closed position;
Fig. 3 is a greatly enlarged fragmentary sec
tional view taken on the line 3_3 of Fig` 2;
Fig. 4 is in part a plan view of the manual and
switch assembly, and in part a sectional view
taken on the line 4_4 of Fig. 1;
`
~
Fig. 5 is a vertical sectional view taken on the
4o line 5_5 of Fig. 4 and showing the mechanism
for shifting the bus bars;
Fig. 6 is a sectional view taken on the line 6_6
of Figs. 1 and 5;
Fig. ’7 is a detail illustrating the method of
" securing the contact arms or switch ilngers in
their mounting plates; and
-
Fig. 8 is a fragmentary vertical sectional view
taken onl the line 8_8 of Fig. 4.
_
5
A further object is to provide an improved
multiple s_witch construction in which the indi
vidual contact _carrying arms may be assembled
A further object is to provide an improved
switch contact for switches carrying currents of
low voltage and amperage.
A further object is to provide an improved
means for actuating multiple switches.
Si)
quencies of the tempered musical scale are lpro-
The key switch assembly of the present in- -
vention forms a part of the electrical Amusical
instrument which is fully disclosed in my Patent
No. 1,956,350, granted April 24, 1934, to which
reference may be had for a-disclosureof the gen
c', au eral construction of the instrumentA and of the
that several hundreds of switches must be pro- 15
would not‘besuitable for use in an instrument
of this character. Furthermore, due to the great
number of switches present in the instrument,
each switch is very simple and cheap so that the 25
instrument may be produced at a reasonable cost.
Another desirable feature of the switches
which is incorporated in the present invention
is that the contacts of the switches are made of
non-corrosive, non-oxidizing, non-pitting con- 3o
ductors.
The usual cheaper contact metals are
unsuitable because they do not maintain a good
contact surface over extended periods of time,
and it has been found that some of the rare
metals, such as platinum, platinum iridium al- 35
loys, and palladium, 'form the most durable and
efficient contacts for this type of circuit. In
the present invention, due to the novel form of
the contacts, the quantity of the rare and ex
pensive contact metal necessary is reduced to a 40
practical value so that even though there are
hundreds of switches in the instrument, the cost ,
of the rare metal necessary for over a thousand `
switch contacts is not excessive.
One oi' the diiilculties formerly experienced 45
with switches of the type usable in electrical
musical instruments was that particles of dust
or other foreign matter settled between the con- ‘
tacts of a switch and rendered the switch in
eiîective. Even a small particle of lint or dust 50
located between the switch contacts will inter-rupt the circuit because of the extremely low
voltage and amperage of the current transmitted
through the switch. One of the features _of the
Present invention is therefore the enclosure of the 55
wires 18. It will thus'be apparent that thever
proof compartment and the' provision of means tical'plates it are held in properly spaced rela
for simultaneously wiping or cleaning a plurality tion at a plurality of points“ so that even though
or all or the switch contacts. Even though the the casing for the' switches is subjected to a load
switch contacts carry currents of low voltage and and deformed to some extent, the proper spacing
amperage; and thus the possibility oi’ damage oi of the-plates it will not be disturbed. The as
_the contact points by arcing vis not present, there sembly as a whole is thusvery ñexible without
is‘mechanical wear u'pon the contacts, and the sacrificing. accuracy in the alignment of the va
'
construction of the present invention therefore rious parts.
A plurality of switch mounting plates t@ and
10 provides means for easily renewing the contact
vswitching mechanism in a substantially dust
points without disassembling the switch unit.
t2 made of. suitablel insulating material, such as a '
Referring to Fig.. l, the key switches are en- ^ phenol condensation product,- are supported by
closed in a dust-proof compartment'composed ` the vertical plates it. These plates il@ and t2
of a sheet metal L-s'haped strip it', a back plate
may be of convenient length, extending approx
-15 it, a bottom sheet Ml, and a top sheet it. ' The i imately the distance between four adjacent ver
switch assembly is supported by a plurality of tical plates it. The lower edge of the insulating
vertical compartment walls it, the. front of each '- -plate til and the upper edge ofthe corresponding
of the compartments-iormedbetween the plates plate t2 are provided with notches of width to
it being enclosed by a ñexible wall til. `lllhe rear receive the vertical plates it, and these notches
wall l2. is secured to the L-shaped strip. iii are interengaged with the vertical plates it by 20
moving the insulating plate tt downwardly and
by cap screws di, `Vertical plates it have up
the insulating plate lit upwardly and then in
wardly extending lugs 22 which project into com
plementary openings formed in the horizontal leg ' Serting locking wires 8d and t6 to hold the plates ' `
_of the L-shaped strip or angle plate it, and have in- their displaced position in locking engagement
25k
. downwardly extending lugs dit near their forward with the vertical plates it. ‘ '
As shown in Fig. 8, the insulating plate llt
ends which project intoapertures formed in the ‘
(which is substantially identical in construction;
horizontal portion of an angle stripqtßl which ex
with the plate' di)4 is provided with a plurality of
tends the full length of the'manual.
The plates it are secured to the angle strips polygonal apertures tt. The contact arms or
.a lll and 2d by cap screws 2t and 2d respectively. switch fingers t@ project through these apertures 30
The cap screws 2t are threaded throughstrips td and are held in position by the rear plate t2,"
il@ which extend the full length oi the manual, 'as best shown in Figs. d and 7. The switch ñngers‘
projecting. through apertures tt formed in the @t are preferably stamped from a thin sheet vof
plates it. The cap screws tt are threaded in ía phcsphorbronze, and at their rearward ends are
~35 long strip 3d which overlies the tops of the :tor-' » provided with an open end slot @t thus. forming 35
ward ends of the vertical plates it, -resting in a >a latch portion 96 and a connection portion @8.
. recess t@ formed in the platesltl. The top sheet ` As indicated in Fig. 7, the switch fingers' tu are
i@ is secured to the vertical plates it by cap .inserted through the apertures di! in the insulat
screws 3d which are threaded in a strip-fi@ ex
ing plates t2 and> til until the latch portion 98
tending thev full length of the manual and pro
is bent inwardly because ci the engagement of 40
jecting through ' apertures _ ¿it? formed in the
its cam surface litt with the edge of the aper
plates.
is bent upwardly
The rearward
as indicated
edge of the
at ¿it
topand
sheet
corn
presses a feltstrip ¿it against the lower i'ace of
ture tt, whereupon the notch itt formed in the`
45 the forward edge of the angle strip it, thus pre-`
portion 'of iï‘ig. 7,' thus securely latching the
contact ñnger against longitudinal movement
'to
venting the admission of dust at the joint be
tween the sheet it and angle strip it." The bot
tom sheet id isseeured to the vertical frame ~plates
it by cap screws #Stand ¿it which are, threaded in
strips t2 and 5ft respectively, these strips projectf» '
ing through. apertures 5d and td respectively
latch portion @t will spring into engagement with
the insulating plate 82, as indicated in the upper
vrelative to the insulating plates t0 and t2.' The ' '
forward 4ends of the switch dngers» @t have va
narrow tip idd, tothe lower surface >cf which >is
welded a,y short length oi wire tilt which is preter 50
ably> marient a palladium alloy, but may be made
of platinum, a platinum iridium alloy, or similar
twee'n the'rearward edge of the lower sheet it vnon-corrosive, non-»oxidizing metal. The wire
and the rear sheet t@ is sealed by a felt strip tt, is preferably, for the sake of economy, of ex,
55 and similar felt strips tt and td seal the ‘upper ' tremely small diameter, in the order of .007" in
formed in the vertical plates it. - The space be'-v
and lower edges respectively oi' the iront com
partment walls it. 'These walls have forwardly'
extending, flanges tt -at their-ends, lsaid ñanges
containing perforations tt.- .As best shown »in
60 Fig. i, wires ‘id extending the full length ofA the
manual are threaded through the periorations tt
diameter. It is found that a. contact made of this
wire will be effective to maire a Igood connection
throughout theuseful lii'e of the instrument.
_The »switch fingers are normally slightly bowed',
as indicated in Fig. l, with their forward tips itt GG.
abutting against insulating strips tdt which .5er
and complementary perforations formed in the> tend the full length oi the manual, and are-Y
threaded >through suitable apertures vformed in
vertical plates' it, and thus hold the walls tti in
position.
65
A
_
`
.
`
"
In addition to being properly spaced by the lugs
insulating bus bar supports lit.- As will be ap-_
parent from Fig. d, bus bar supports _iid are 65
22 and 2t, the vertical plates it are spaced by located between successive pairs ot dies or switch' ^
strips i12, "it, and lift. These strips are each pro- `* fingers dit, andare supported by a pair oi’ rods
M2 which extend the length or the manual and
vided with notches 'il in one edge- ther-eci, the
notches being oi' sumcient width to receive the are threaded through complementary holes in the...
70 plates it. After sliding the strips "i2, lid, and 'itâ
bus bar supports il@ and in the vertical plates itl.
through the complementary shaped apertures
The bus bar supports il@ are suitably spaced by
formed therefor in the vertical plates iii, the ' the notched strip it, thisstrip having notches-to
strips are moved laterally'to bring their notches y engage the bus bar supports as well as notches
for engagement withïthe vertical plates lil. The
_and the strips heid in this'pcsition by pairs of bus bar supports Vl i@ are provided with generally
.intopintermeshing engagement with the. plates,
7o
3
L-shaped openings I|4, the horizontal portions
upon and may be secured to the strip 04. Each
oi' the black keys |30 is secured to the channel |00
by a pair of cap screws |02, |04 which are screwed
into suitable threaded sockets molded into the
of which receive the insulating strips |00 and the
vertical portions of which receive bus bars H0.
(It will be noted that the uppermost insulating
strip '| 00 merely forms an upper limit stop for the body of the key |30. Both the white keys |34 and
switch finger and does not support la bus bar.)
the black -keys |00 are guided against lateral
'I’he bus bars ||0 extend the full length of shifting movement by fabric pads |00 which are
the manual and rest upon the insulating strips secured to the upwardly extending teeth |00 of
|00 and are guided for longitudinal movement in a comb |10 by U-shaped clips -|12. The comb
10 the vertical portions of the L-shaped slots I|4.
` |10 has its horizontal flange portion |14 which is
The bus bars are preferably made of nickel alloy secured in place byl cap screwsv |10 projecting 10
and have a wire | I0 of palladium or other suit
through the lower sheet i4. Downward move
able metal welded or otherwise suitably secured ment of the keys is limited by a felt strip |11
thereto. In the preferred construction, the wire which. is held in position by pins |10 which are
||0 is spot welded to the bus bar H0 at short
riveted to the flange 314.
15
intervals along 4the length of the wire. This
Upward movement of the black keys |30 is
wire is preferably softer than the wires |06 used limited by'a felt pad |30, which is secured by a
on the switch fingers in order that if wear takes prong |02 forming part of a clip |04, the latter
place between them, the >bus bar contact wire being secured between the channel |30 and the
shall wear substantially to the exclusion of wear
on the contact wires |06.
y,
The switch. iingers 910 are iiexed so as to bring
their contact wires |00 into electrical contact
with the contact wires |00 of the bus bars | I0 by
means of actuators |20, which, as shown in Fig-2,
are provided with apertures |22 through which
the switch fingers 90 project. The actuators |20
abut shoulders |24 formed on the switch fingers
00 and are held against movement away from the
30 _shoulders |24 by a block |20 of insulating material
which projects through apertures |20 formed in
ali of the switch ñngers 90 except the uppermost
and lowerxnost fingers of a tier. The insulating
block |20 thus rests upon the lowermost switch
35 >linger 00 and is held against removal by the
uppermost of the switch fingers.
The upper ends of the‘actuators |20 are of
reduced width, and project through suitable slots
formed in the top sheet i0 of the switch com
40 partment and through a thin sheet of felt |30
which is secured to the top sheet I0 by me
tallic strips |32 which may be riveted or other
wise suitably secured to the top sheet I0.
Inasmuch as the construction of »the manual,
that is, the construction of the keys and sup
ports therefor, is more fully described and is
claimed in my copending application, Serial No.
91,283, ñled July 18, 1936, the construction and
operation of these parts will be but brieily de
50 scribed herein.'
Keys |34, |30 molded o! a suitable plastic com
position-are secured to key stems in the form of
metallic channels |30 which are supported on
studs |40 and rest upon a fulcrum rod |42. The
studs |4|0 are riveted to the horizontal leg por
tion of the angle strip i0 and at their upper ends
are of reduced diameter and are threaded to
receive adjusting nuts |44 by which the degree
of compression of coil springs |40 which sur
60 round the studs |40 may be regulated. A grooved
wooden strip |40 may be placed over the row of
adjusting nuts |44 to prevent the accidental
loosening
'65
thereof.
v
l
.
A
Each of the channels |30 has a felt pad |50
suitably secured thereto for providing a noise
less contact with the upper end of its associated
, actuator |20. Upward movement of the forward
7.0
ends of the white keys |34 is Alimited by a felt
strip |52 secured to the lower surface oi' the in
wardly extending flange |54 of an angle strip |50
which is secured to the angle 24. The felt strip
|52 is engaged by an integrally molded projec
tion |50 formed at the forward end of each of the
body of key |36 by the cap screw |02.
- 20
As previously intimated, the bus bars H0 are
>.longitudinally slidable relative to the bus bar sup-ports i i0. As best shown in Figs. 4 and 5, the
ends of the bus bars H6 are bent over and the
ends clamped between a pair of insulating plates 25
|80 and §88 by a pair of cap screws |00. ’I'he in
sulating plate |80 is riveted to one arm |92 of a
bell crank lever |84 pivoted upon a pin |96 sup
ported in a bracket |00. The bracket |90 may be
secured to the leftmost vertical plate I0 by a pair 30
of cap screws 200. The other arm 202 oi' the bell
crank |94 has an open end slot ‘in the form of
a yoke‘embracing the reduced diameter portion
204 cfa spindle 200. ri'he spindle 200 has a
threaded portion 200 screwed into an internally
threaded block 2|0 supported by the leftmost
vertical plate |0.
The portion 200 is threaded ,
into a kerfed shank 2|2, being secured against
unscrewing by a pin 2|4 extending diametrically
through the shank 2|2 and the threaded portion 40
200. The shank 2|2 extends through an aper
ture 2|6 formed in the rear sheet l2, a suitable
washer 2i0 made of phenol condensation product
`or similar material being held by a compression
coil spring 22 in position to seal the opening 2| 0
against theadmission of dust. The inner end of
the spring 220 abuts against a washer 222 which
in turn abuts against the projecting ends of the
pin 2|4. The spring 220 not only holds the wash
Aer 2|0 in place, but exerts a longitudinal pres
,sure upon the threaded portion 200 of the spindle
so as to increase the friction and prevent unde
sired rotation of the spindle due to vibration.
As will be noted from Figs. 4 and 7, each of the
projections 00 of the switch fingers 00 has an
insulated German silver resistance wire 224 weld
ed thereto. These wires 224, one from each of
the switch iingers 00, are led through notches
220 formed in an insulating strip 220 clamped 60
between a metallic channel 230 and the bottomk
sheet I4 by the cap screw 40. 'I'he wires are
then led over a fiber or other suitable insulating
sheet 232, which is held in spaced position by a
tube 234 of insulating material. Ametallic chan
'nel 230 is clamped to the bottom sheet I4 by cap
screws 50, and this channel, as well as‘the two
arms of the channel 200, carry notched combs
230, 240, and «.242 of insulating material. vT'he
wires 224 in addition to forming van electrical 70
connection between the switch fingers 00 and the
generators form an important part of the elec
trical'circuit of the instrument by providing a
keys |04. Downward movement of the keys |04 - predetermined high impedance path for the ñow
75 is limited by a heavy felt pad |00 which rests of the’current from >the generators to the output 75
>apea'ace
circuit. To obtain’the predetermined resistance
in the wires‘224, they are measured to a certain
length (approximately a yard long). lli.’ means
were not provided to mount these hundreds of
.
the contact wire m6. By substantially concen
trating any mechanical wearing of the contact
wires upon the bus contact wire ||8, it is pos
sible easily to` compensate for such wear by shift
long wires, they would become tangled and
ing the bus bars.
2M, a> plurality of -which are riveted to an insu
tact, and while holding the key depressed shift- .
.
.
In the event that one of the switch contacts
snarled and the combs 238, 240, and 242 are there
fore provided as a means to support the excess becomes defective due to the adhesionv of a par- f
length of the insulated resistance wires 22d. As ‘ ticle of lint or dust, such particles may usually
will be noted from Fig. 6, oneend of each of the be very easily removed by depressing the key
10 resistance wires 22d is soldered to a soldering lug controlling the switch having the defective con
lating strip 246 riveted to the channel 226i. The
intermediate length of wire is strung back and
forth between the appropriate slots in the combs
15 23B, 2li@ and 2d?! so that the wire will be taut
throughout its length.
It will be understood
that a, plurality of wires 226| will be connected
to one of the soldering lugs 2M and that these
wires, although of the same length, must be
20 connected to different tiers of switch ñngers.
Wires 25tconnéct the’ soldering lugs 2M to the
generators. (The 'particular connections neces
sary are fully disclosed in the above mentioned
Patent No. 1,956,350.) The wires 22d strung up
25 on the combs 233, Mil and M2 are covered by
a horizontal extension 2M of the rear sheet |12,
the horizontal extension being secured to the bot
tom sheet |it by screws 250 threaded in suitable
spacing studs 252.
It is believed that the operation of the key
switches will have been apparent from the pre
ceding detailed description of their construction.
Briefly, upon depression of one of the keys Wd or
|36, the channel stemk mt thereof will, in swing
35 ing downwardly, engage the upper 'end of the
associated actuator |20. The'actuator will there
upon flex downwardly all of the switch fingers t0
of a vertical tier or file until the contact wires>
|06 of the switch fingers are ñrmly pressed
40 against the contact wires ||8 of the bus bars Ht,
completing the circuit from the generators (which
are connected by wires 254 to the soldering lugs
244) to the output circuit which is connected -to
the bus bars | i6. Upon release of pressure upon
the depressed key, the compression spring |86
will swing the forward end of the key upwardly,
whereupon the switch fingers 90 . will, `due to
their resiliency, resume the position in which
they are shown in Fig. 1, where their tip portions
|04 are arrested by engagement with the insulat
ing strips |00.
ing the bus _bars back and `forth by rotation of
the spindle shank 2|2. If desired„all of the
switch contacts may be simultaneously cleaned
>by holding all of the keys depressed and shift
ing the bus bars back and forth.
From the above description, it will be noted
that the manual and the key switches form a
unit which is electrically connected to the in
strument by many 'less wires than there are sep
arate key-actuated switch circuits. Thus in the
event of damage to the manual of an instrument,
it may be easily removed for repair or replace
ment. Furthermore, this construction lends it
self very advantageously to production of the in 25
strument in large quantities at low cost.
It will _be noted that the assembly of the switch
ñngers 90 in their supporting-plates 80 and 82
and their connection with the actuator |20 is
easily accomplished, since it is necessary merely 30
to slide these iingers through the apertures 88
in the plates B0 and 82 and through the aper
tures |22 in the actuators |20 and to drop the
insulating block |26 in position just prior to in
serting the uppermost of a tier of switch iin
gers
90.
M
-
c
35
~
'I'he construction is such that although there
are several hundred: switches, the assembly of
them is very compact, with thev result that the
switches of each tier ïmay be located directly be 40
neath, or in the plane of, the-key used to actuate
them, and despite the large number of switches
required, the cost of the switch assembly' is rel
atively small.
While I have shown and described a preferred 45
embodiment of my invention, it will be readily
understood by those skilled in the lart that varia
tions may be made in the constructiondisclosed
without departing from the basic features of my -
invention.
I therefore do not wish to beìlim-v
ited to tlfe precise construction disclosedî` but
-
wish to include within the scope of my invention
all suclnequivalent modifications and variations
switches should fail to make contact, the-portion ~ which~will readily suggest themselves to those
of the contact wires | |8 which is engaged with the skilled in the art.
.
. 55
contact wire |06 on the switch ñngers; may be
What I claim as new -and desire to secure by
shifted so as no longer to be in'registry with the Letters Patent of the United States is:
If, after a long- period of use, some of the
60
contact wires |06. This is accomplished by turn
ing the shank 2|2 of the spindle 206 and thus
through the bell crank |94 pushing or pulling the
l. In an electrical musical instrument, the com
bination of a manual composed of a plurality of
keys, a bank of switch ñngers for each key, said
bus bars ||6 in one direction or the other. In
banks of switch ñngers being arranged in planes
asmuch as the contact wires |06 are of exceed _ each in substantial alignment with its associated
inglysmall diameter, a slight longitudinal move
key, a plurality of bus bars extending in a di
ment of the bus bars will result in bringing new rection perpendicular to the planes of said banks
portions of the bus contact wires ||8 _in registry of switchv fingers and each bus bar being 1o
with the contacts |06 of the switch fingers. Since cated in a position to be contacted by _one of
. the contact wires |04 flex as their contacts |06
the switch iingers of each bank, and an actua
are brought into contacting engagement with the tor for each bank of said switch-fingers oper
bus contacting wires ||8, therey will be a very able by the associated key to move the switch
iingers into engagement with said bus barsre
70 slight wiping action, assuring a good contact.
This wiping action results, however, in slight me- '
spectively.
2. In. an electrical musical instrument, the
it is softer than the contact wire |06 and it is ' combination of a manual composed of a plu
for this reason that the-latter wire may, if de- ' rality of keys, a bank of switch ñngers for each
chanical wear of the bus contact wire Md since
75
sired, be made ofv slightly greater diameter than . key, said banks of switch fingers being arranged
25,099,264
in planes each in substantial alignment with its
associated key, a plurality of bus bars extending
in a direction perpendicular to the planes of
said banks of switch ñngers and each bus bar
being located in a position to have a portion
thereof contacted by one of the switch fingers
of each bank, actuators individual to each bank
of said switch fingers and operable by said keys
respectively, and manually operable means to
simultaneously shift all oi said bus bars longi
tudinally thereby to bring diiïerent portions
thereof into position to be contacted by said
switch ñngers.
3. In an electrical musical instrument, the
combination of a manual composed of a plu
5
said insulating strips into contact with said bus
bars respectively, and means to move said bus
bars longitudinally.
_
9. In an electrical musical instrument the com
bination of a plurality of similar tiers of switch
fingers located in a row, a plurality of perforated
bus bar supports of insulating material, a plu
rality of bus bars mounted in said supports and
located in positions to be contacted by said switch
fingers, an insulating strip located beneath each 10
of said bus bars and forming a linut stop for said
switch fingers, andmeans‘to move a tier oi switch
lingers from engagement with said insulating
strips into contact with said bus bars respectively.
l0. A switch for electrical currents of low volt
age and amperage comprising a movable switch
rality of keys, a bank of switch fingers for each
key, said banks of switch fingers being arranged " :finger having a short length of contact wire se
in planes each in substantial alignment with its cured thereto, and a second relatively nxed conm
associated key, _a plurality of bus bars extend
tact wire extending at an appreciable angle with
20 ing in a direction perpendicular to the planes
respect to said iirst named contact wire and co-l
of said banks
switch fingers and each bus bar operable therewith Ato complete an electrical cir-~ 20
being located in a position 'to be contacted by cuit, said wires being in the order oi' .067 inch
one of the switch iingers of -each bank, an actua
in diameter.
tor for each bank of said switch ilngers oper
25 able by the associated key to move the switch
iingers into engagement with said bus bars re
spectively, and means vto shift said bus bars lon
-gitudinally~
4. In an electrical xuusicai instrument, the
combination of a plurality of conductors, each
connected to a source of alternating current, key
operated switches for selectively connecting said
conductors tc an output circuit, a. housing for
said switches, resistance 'wires connecting said
35 conductors with said switches, and a plurality of
combs mounted on said housing and forming
supports for Stringing said wires.
5. In a multiple switch, a pair of spaced plates
of insulating material having similar rows and
40 illes of periorations formed therein, a pluralityY
of movable switch ilngers extending through said
perforations and each having a `part engaging
one of said plates detachably to hold the switch
iinger against longitudinal movement with re
spect to said plates, fixed contacts for said switch
fingers, and an actuator having parts engaging
each of the switch ilngers of a ñle and operable
to iìex the latter into contact with said ñxed
contacts.
>
6. In an electrical musical instrument, the
combination of a plurality of conductors, each
connected to a source of alternating current, key
operated switches for selectively connecting said
_conductors to an output circuit, relatively long
55 Wires of predetermined impedance connecting
said conductors with said switches, and a plu
rality of notched insulating strips ñxed-with re
spect to said switches and forming supports for
Stringing said Wires.
60
-
7. A switch finger comprising a thin strip o!
resilient metal having a latching part cooper
able with a support detachably to hold the ñnger
against longitudinalmovement relative- to the
support.
"
8. In an electrical musical instrument the
combination of a plurality oi' similar tiers of
switch fingers located in a row, a plurality of
perforated bus bar supports of insulating mate
rial, a plurality of bus bars mounted for sliding
70 movement through the perforations in said sup
ports and located inv positions to be contacted
by said switch merk, an insulating strip located ~
il. A switch for electrical currents of low volt
age and amperage comprising a movable switch 25
ilnger having a short length of contact wire se
cured thereto, a second relatively iixed contact
wire extending at an appreciable angle with re
spect to said first named contact wire and co
operable _therewith to complete an electrical cir 30
cuit, said wires being in the order of .O07 inch in
diameter, and means to shift one of said contact
wires longitudinally to bring a dlñerent portion
lhereof into cooperable contacting relationship
with the other of said wires.
35
l2. In a multiple switch assembly, the com
bination of a plurality of spaced switch finger
supporting plates each having a plurality of per
iorations therein substantially aligned with the
perforations in the other, switch iingersvhaving 40
apertures and shoulders and extending through
aligned periorations in said supporting plates,
cooperating means on said iingers and one of said
plates for holding said ilngers against longitudi
nal movement with respect to said plates, an ac
tuator embracing a plurality of said lingers and
abutting the shoulders thereon, and a block of
insulating material extending through the per
!orations in said ilngers and operable to prevent
appreciable movement of said actuator in a di
rection away from the shoulders on said fingers.
50
13. In an electrical musical instrument, a uni
tary manual and switch assembly, comprising a
plurality of keys, a plurality of switches oper
able by said keys, terminals mounted on said as
sembly for connection to diñerent electrical gen
erators, and a plurality of wires each having one
end connected to one of said terminals and
their other ends connected to diil’erent ones of
said switches, whereby the assembly may be dis 60
connected from said generators without discon
necting said wires.v
.
'
14. In an electrical musical instrument, the
combination of a manual assembly comprising a
plurality of keys, a plurality of switches associ 65
ated with and operable by each key, a plurality
of terminals mounted on said manual assembly,
and a plurality of wires connecting said switches
with said terminals, there being only one of said
wires connected at one end to eachv of said 70
switches, and a plurality of said wires connected
at their other ends to a singlev one oi’ said ter
beneath each oi said bus` bars` and forming a‘l minals, wherebyconnection of a singleconductor
limit stop for said
ß?gers,
to move to one oi' saidterminals'may be eilective to sup
75 a tier 'or switch fingersk han 'engagement with 'pb canut to a plurality oi' said switches.
accenna
i5'. A vswitch assembly for electrical currents
of low voltage and amperage comprising a plu
rality of movable switch members, each having
a short length of contact wire secured thereto,
-a bus element common to a pluralityV of said
switch members and having a contact wire se
cured thereto in electrical conducting relation
ship, said bus contact wire extending at an ap
preciable angle with respect to said switch con
Mi tact'wires and beingr cooperable therewith to com»
> plete electrical circuits, and means to shift said
bus element with respect to said switch members
thereby to make possible the’ cleaning of- said
contact Wires by a rubbing action.
'
16. In an electrical musical instrument the
combination of a plurality of switches each com
prising a pair of cooperable contacts, one of the
contacts being normally stationary and the other
movable'into engagement therewith, and means
20 for simultaneously vmoving the normally station
ary one of each pair of said contacts with re
spect to the other or the pair, thereby to clean
contact metal secured to said bus vbar in elec
trical conducting relationship therewith, and
means selectively to move said switch-members
into contact with said contact wire.
18'. In a multiple switch- assembly for currents
of low voltage and amperage, a row of switchv
members, each having a contact wire of precious
lcontact metal secured thereto, a bus bar of a base
metal positioned adjacent said members, a con
tact- wire of precious metal secured to said bus
bar in electrical conducting relationship there
with and extending at an appreciable angle with
respect to the contact wires of said switch mem
bers, means selectively to move the contact wires
oi’ said switch members into contact with the
contact wire of said bus bar, and a manually
operable means to shift said bus bar with respect
to said switch members to change the points
of contact between its contact wire and the con
tact wires of said switch members.
,
l9.`As an article of manufacture, a switch
finger comprising a thin strip of resilient metal
the contacts by a rubbing action or to cause having a Support-'engaging notch formed in a
one of the contacts of each pair to engage the side edge adjacent one end thereof and having 25
a slot extending longitudinally of the strip at
.25 other at a point spaced from the original point of ' said end, whereby the portion of the strip near
. contact.
'
17. lin ay multiple switch assembly for currents ` said notch will easily flex to permit disengagement
of the notch from a support'.
`
t ‘
of low voltage and amperage, a row of switch
members, a bus bar of a base metal positioned ad
nAUnnNs’ Harmonia. 30
ß jacent said members, a contact wire oi a precious
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