Note: Descriptions are shown in the official language in which they were submitted.
16 BACKGROUND OF THE INVENTION
17 The present invention relates to pressure sensitive
18 variable resistance devices, and in particular to devices
19 having a thin layer of particulated semiconductive material
20 with a multiplicity of surface contact protrusions disposed
21 between at least two electrical contacts.
22 The generation of musical sounds by electronic
23 means is well known. However, one problem which exists in
24 most electronic instruments ls the inability to continuously
26 vary either the volume or the tonal quality of the sound
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1 generated. This inability limits the musician's freedom of
2 musical expression. The present invention provides novel yet
simple pressure responsive analog devices having a c~ntact
4 resistance which varies inversely with the amount of pressure
5 applied to the device. When used in electronic musical
6 instruments, a plurality of such analog transducers or switches
7 may be placed side by side in an elongated fashion to provide a
8 keyboard or one such switch may be used to effect changes in
9 tone by altering the characteristics of one or more tone
lP generating circuits in the musical instrument.
11 Pressure sensitive analog switches have been known.
12 For example, both in Ruben, Patent No. 2,375,178, and Costanzo,
13 Patent No. 3,386,067, analog switches are disclosed which
14 sandwich a fibrous or sponge-like layer containing a conductive
15 material between two conductor plates. As the two conductor
16 plates are compressed the number of electrically conductive
17 paths increases, thus decreasing the electrical resistance.
18 However, the resistive layer must be resilient to force the
19 electrodes apart when the compression force is released.
20 Furthermore, the resistive layer depends on macroscopic
21 compaction to increase the number of electrical conductive
22 paths, and ccnsequently, must have a relatively large
23 thickness. Finally, in such devices the resiliency of the
24 sponge-like layer can decrease with use causing a degeneration
25 in operating characteristics.
26 ___
1153~1
1 In Mitchell, Patent No. 3,806,471, pressure responsive
2 semiconductor materials, e.g., molybdenum disulfide, is placed
3 between conductor plates to provide an adjustable resistor or
4 transducer. However, Mitchell relies on volume resistance, i.e.,
the resistance through a relatively thick volume of the
6 molybdenum disulfide layer. The present invention on the other
7 hand uses the contact or surface resistance of a very thin
8 layer of molybdenum disulfide. More specifically, Mitchell
9 discloses a molybdenum disulfide volume (thickness) of .001 to 1.0
inch using molybdenum disulfide particules in the range of 50
11 to 600 mesh to provide a high but finite number of three-
dimensionally distributed current flow paths through the
resistive material. under compression, the number of current
14 flow paths between the particles in the volume increases, thus
15 causing the resistance to decrease. The semiconductor volume
16 layer i, then permanently positioned and attached between two
17 conducting electrodes.
18 In addition to the above-described functional
20 distinction, the structures disclosed by Mitchell require
21 that the semiconducting volume be positioned between two
2Z conductors or between a conductor and an insulative plate in
23 intimate contact with either the insulative plate or the con-
24 ductors. Such a configuration is fundamentally different from
applicant's invention where the semiconducting composition
layer must necessarily have at least one contact surface which
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1 is not in intimate contact with either a conductor or another
2 semiconducting layer~ Such an arrangement takes advantage of
3 the physicalcontact resistance over the surface of the composition
4 rather than the surface resistance of the individual particles
through the volume of material as in Mitchell.
6 The present invention uses particle sizes on the order
7 of one micron and layer thickness preferably less than .001 inch.
Furthermore, since the variable resistance occurs because of
9 a greater or lesser number of surface contact locations, one
surface of the semiconductor layer must either be initially spaced
11 apart from one of the conducting electrodes or must be in non-
12 intimate contact with the opposing surface. Depression of the
13 conducting electrode against the surface of the thin semiconductor
14 layer results in a plurality of contact points being made along
the surface. These contact points increase as pressure is applied
16 thus decreasing the resistance between the conducting plates
17 or contacts on either side of the semiconductor layer. The semi-
18 conductor layer is made of any suitable particulated semiconductor
19 material held together and to the surface with a binder.
A significant advantage of the thin semiconductor layer
21 of the present invention is that the semiconductor material used
to form the layer may be combined with a binder and a binder
23 thinner and thereafter sprayed or silk-screened onto the
desired surface to form a layer having a thickness as little
26 ___
115~801
1 as one mil or less. Labor and material costs are thus greatly
2 decreased.
3 In addition to the above advantages, the use of molyb-
4 denum disulfide to cover the conductive layers effectively
~ protects the surface of the conductor from contact with the air.
6 This alleviates a serious problem which has been attendant with
7 using conductors which slowly corrode when exposed to the air.
The present invention also substantially eliminates
9 the electrical chatter which is inherent in most switches.
10 Consequently, the resultant switch structure is bounceless.
11
12 In Pearlman, et al., Patent No. 4,044,642, a
13 touch sensitive resistance device is disclosed for use in
14 musical instruments. However, the device uses a semiconductor
material sandwiched between two conauctor plates in a manner
16 similar to Ruben and Costanzo. Specifically, Pearlman, et
17 al. uses a resilient material such as foam rubber or foamed
18 synthetic polymeric material which has a particulate material
19 such as graphite dispersed throughout. The switch structure
has a foam semiconductor layer and an insulator layer with
21 an orifice therethrough sandwiched between two conductor
22 plates. Thus, when a compression force is applied, the
23 graphite-saturated resilient foam layer deforms into the
24 orifice in the insulator material to initially make electrical
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1 contact to thereby switch on the musical instrument. Thereafter,
2 additional compression force causes the resistance between the
3 two conductor plates to decrease in the manner previously
4 described.
It is therefore desirable to provide analog transducer
6 devices which do not rely upon the resiliency of the semi-
7 conductor layer and which do not furthermore rely on the volume
8 resistance through a relatively thick semiconductor layer.
9 One particular embodiment of the invention comprises
a number of chord switches in a keyboard arrangement so that
11 when a chord switch is depressed one or more musical notes will
12 be generated. The particular chord may be easily altered by
13 simply rolling the finger which is applying the transverse
14 touch force.
In another embodiment of the present invention, a dual
16 switch touch sensitive structure has dual switches which are
17 simultaneously actuated in response to a single touching force.
18 A semiconducting composition may be disposed over the switch
conductors (contacts) of at least one of the switches so that
; the resistance across the contact of that switch varies inversely
21 to the amount of force applied.
22
23 SUMMARY OF THE INVENTION
24 The present invention comprises pressure responsive
26 analog swi hes and transducers hsving s resistance which varies
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1 inversely to the amount of compression force applied to the
2 switch.
3 The pressure sensitive transducer includes a thin,
4 pressure sensitive, semiconductor composition layer disposed
on the surface of a resiliently movable cover. Altneratively,
6 the pressure sensitive semiconductor layer comprises a third
q conductor, such as a layer of silver, on a surface of the
8 cover in an enclosure and a pressure sensitive semiconductor
9 composition layer disposed on at least one of a first and
second contact conductors.
11 Other embodiments of the invention include a pressure
12 transducer device and simultaneously actuated multiple switch
13 devices.
14
BRIEF DESCRIPTION OF DRAWINGS
16 A complete understanding of the present invention and
17 of the above advantages may be gained from a consideration
18 of the following description of the preferred embodiments taken
19 in conjunction with the accompanying drawings in which:
FIGURE 1 is a cross-sectional plan view of one
21 embodiment of a pressure responsive analog switch with the
22 pressure responsive coating positioned between two conductor
23 plates in a spaced relationship.
24 FIGURE 2 is a cross-sectional side view of a
bounceless switch apparatus in accordance with the invention.
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1¦ FIGURE 3 is a pressure versus voltage curve
21 illustrating the variations in voltage across the semiconducting
3 ¦composition layers as the compression forcing those two layers
4 together is increased.
FIGURE 4 is a curve illustrating the output of the
6 bounceless switch in accordance with the invention shown in
7 FIGURE 5.
8 FIGURE 5 is an illustrated embodiment of the
9 bounceless switch apparatus in accordance with the invention
10 having only one semiconducting composition layer.
11 FIGURE 6 is an exploded partial pictorial partia~
12 schematic diagram of a dual lateral transducer switch in
13 accordance with the present invention in an unfolded, open
14 configuration.
FIGURE 7 is a cross sectional side view of the
16 switch apparatus shown in FIGURE 6 in the folded operating
17 configuration through section 7-7.
18 FIGURE 8 is an exploded partial pictorial, partial
19 schematic of another embodiment of the dual lateral switch
20 embodiment of the invention.
21 FIGURE 9 is a partial schematic, partial cutaway
2Z perspective view illustrating one chord switch structure in
accordance with the present invention.
24 FIGURE 10 is a cut-away side plan view of a dual-
function, touch-switch apparatus in accordance with the invention.
26 ___
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1 FIGURE 11 is an exploded cross-sectional side view
2 of one embodi~ent of a pressure transducer in accordance with
3 the invention.
4 FIGURE 12 is a top plan view of the flexible base
member of FIGURE 11 in an unfolded configuration showing the
6 conductor patterns disposed thereon.
7 FIGURE 13 is an exploded cross-sectional side plan
8 view of a second embodiment of the pressure transducer in
9 accordance with the invention wherein the top of the flexible
lP base constitutes a flap disposed to move transversely about
11 a hinge portion.
12 FIGURE 14 is a top plan view of the flexible base
13 used in FIGURE 13 in an unfolded configuration illustrating
14 the conductor patterns disposed thereon.
FIGURE 15 is a simplified partial cross-section and
16 partial schematic view of a musical instrument incorporating
17 a pressure transducer as illustrated in FIGURES 11 to 13.
18 FIGURE 16 is a top plan view of the flexible base
19 used in E'IGURE 13 in an unfolded configuration illustrating
another conductor configuration.
21
DETAILED DESCRIPTION
23 Referring first to FIGURE 1, an analog switch in
24 accordance with the present invention is shown comprising a
25 ~ flrst cond tor plate 50 spaced from a second conductor
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1 plate 52 by spacer portions 54 to define a gap or chamber 60
2 between the first and second conductor plates 50 and 52. At
3 least one of the conductor plates 50 or 52 is resilient so that
4 it may be depressed against the other conductor plate to
close the switch.
6 The conductor plate may comprise a flexible support
7 sheet 64, such as Mylar, with a thin conductive layer 66 of
silver or other conductive material sprayed, screened or
9 otherwise applied on the surface of the support sheet 64
adjacent the second conductor plate 52. The second conductor
11 plate 52 may comprise a rigid plastic base member 68 with a
12 thin copper surface 70 disposed thereon. Of course, it will
1 be appreciated that the base member 68 may be flexible and
14 the thin surface 70 may be made of silver or other suitable
1 conductive material. A lead 56 and a lead 58 may be coupled
to the silver layer 66 and the copper surface 70 respectively
17 to allow for electrical coupling of the analog switch to a
1 utilization circuit.
9¦ Finally, a thin semiconductor layer 62 of semi-
20 conductor material is sprayed, screened or otherwise evenly
21 applied on the copper surface 70. Alternatively, the semi-
22 conductor material 62 may be sprayed, screened or otherwise
23 evenly applied on the conductive layer 66 or on both the
24 copper surface 70 and the conductive layer 66. The semi-
conductor material may be any suitable composition which is
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1 sprayable, screenable, or otherwise of a consistency which
2 may be evenly applied to Eorm a smooth exposed surface. For
3 example, the semiconductor material may be molybdenum disulfide
4 particulate having particle sizes on the order of one to ten
5 microns mixed with a binder material such as resin to form a
6 liquid. A resin thinner may be added to give the composition
7 a consistency suitable for spraying. The thin semiconductor
8 layer 62 of tlle semiconductor material is then sprayed or
9 screened on the conductive layer 66 of the support sheet 64
10 or on the-copper surface 70 on the rigid base member 68. It
11 will be appreciated, of course, that the semiconductor layer
12 may be of any thickness so long as there is an exposed smooth
13 semiconductor surface. However, in order to conserve on
14 semiconductor material and to minimize surface irregularities
15 which may occur when thick semiconductor layers are utilized,
16 a thickness on the order of about .001 inch or less is preferred.
17 The spacer 54 may take various forms. For example,
18 in one partic~larly sensitive embodiment shown in Figure 1,
19 the spacer 54 is simply an extension of the support sheet 64
20 where the support sheet has been creased about all or a portion
221 of the periphery of the usable portion of the conductive layer
23 66. The crease 20 acts like a spring tending to maintain the
spacing in opposition to an external pressing force or pressure.
24 Thus the crease provides not only the means of spacing but
25 also gives the member 50 a resiliency which significantly
26 ___
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1 enhances the sensitivity of the transducer.
2 I It will be appreciated that the configuration of
.~ FIGURE 1 is illustrative only. Thus, the semiconduc~or layer
4 62 may be disposed on one or both of the support sheets 68
or 64 or may be placed directly on the support sheet 66 to act
6 as a shunt between conductors 56 and 58 when conductor 58 is
7 placed on the support sheet 68 in laterally spaced relationship
8 to the conductor 56.
9 Referring to FIGURE 2, another embodiment of
the invention is illustrated for providinq a bounceless
11 switch apparatus having a surface contact resistance which
varies inversely with a pressure applied normally thereto.
13 Specifically, a bounceless switch apparatus 100 has a first
14 supp~rt member 102 which may be made out of ~lylar, a ricid
plastic material, or any other suitable nonconductive base
6 material. A first conductor 10~ is disposed on the surface
of the support member 102 with a first pressure sensitive
18 composition layer 106 disposed thereon to cover and be in
21 intimate contact with the conductor member 10~.
Ju~taposed normally opposite to the first pressure
22 sensitive composition layer 106 is an assembly comprising a
24 s.upport member 110, which may be ~lylar, rigid plastic, or
any other suitable nonconductive material, a conductor
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1 member 112 dis~osed on one surface of the support member
2 110, and a second pressure sensitive composition layer 11~
3 disposed to cover and be in intimate electrically cQnducting
4 relationship ~ith the conductor 112. The assembly comprising
the seconcl support 110, the second conductor me1~ber 112, and
6 the second pressure sensitive composition layer 11~ is
7 positioned in facing relationship with the assembly compris-
8 ing the first member 102 to the first conductor n;ember 104
9 and the first pressure sensitive composition layer 106 so
that the exposed surface 108 of the first pressure sensitive
11 composition layer 106 is in nonintimate but touchinq relation-
12 ship with the exposed surface 116 of the second pressure
13 sensitive CCmpOsitiQn layer 11~ to therehy clefin~ a nonintimate
14 contact junction 118. `
~
16 The first and second pressure sensitive composition
17 layers are made out of a particulated semiconducting material
18 having particle sizes which are preferably on the order of one
19 to ten microns, although larger sizes are possible. The
particulated semiconducting material is then mixed with a
21 binder material and, if necessary, a binder thinner, and then
22 is sprayed, silk-screened or otherwise disposed on the conductors
23 104 and 112 respectively. Each resulting pressure-sensitive
2~ composition layer 106 and 114 thus has a number of particles
which extend outwardly from the mean surface plane of the
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1 respective pressure sensitive composition layers 106 and 114
2 to form micro protruslons o~ yarticulate selr,iconducting
3 material. It is these microprotrusions which allow the
4 first and second pressure sensitive composition layers to
touch wi~hout being in intimate electrically conducting
6 relationship. However, when pressure is applied compressing
7 the two surfaces toyether, the microprotrusions on the
8 respective pressure sensitive composition layers are depressed
9 toward one another forming more and more electrical contact
points, thus decreasing the resistance across the junction
11 118. I~owever, because there is already a small number of
12 electrically contacting touching points (although these are
13 extremely ~`ew resulting in a very high resistance when
14 the respective pressure sensitive composition layers are not
being depressed against one another), the chatter which
16 results when mechanical contacts are brought into contact
17 with one another in conventional switches is virtually
18 eliminated. Furthermore, any chatter which might be
19 generated occurs only when the resistance across the junction
118 is extremely high thus making the voltage drop across
21 the junction 118 likewise very high thereby making the relative
22 voltage exc~lrsions or variation very small.
23
24 In operation the pressure is applied to compress
the respective pressure sensitive composition layers
26 towards one another so that the resistance across the
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1 junction 118 decreases as the number of contact points between
2 the microprotrusions of the particulate semiconducting material
3 increases thus causing the voltage drop across the j~nction to
4 decrease. This, in turn, results in an increase in the output
5 voltage at 128 as shown in FIGURE 3. By coupling this voltage
6 to the threshold circuit 122, a bounceless transition from
7 the OFF to the ON state at the output 130 can be achieved as
8 generally illustrated in F~GURE 4.
9 Of course it will be appreciated that a threshold
lO circuit is not necessary in many types of circuits particularly
11 those using CMOS-type circuitry which has inherent thresholding.
12 An alternative embodiment of the invention with
1 only one of the ccnductors having a pressure sensitive composition
14 layer disposed thereon is shown in FIGURE 5. Specifically, a
1 conductor member 132 is disposed on the top of an insulative
1 support member 130 with a pressure~sensitive composition
17 layer 134 disposed to cover the conductor 132 and be in
1 intimate electrically conducting relationship therewith.
19 A second conductor member 138 is similarly disposed on a second
support member 140. The second conductor 138 is then positioned
21 in nonintimate but touching relationship with the exposed surface
2 136 of the pressure sensitive composition layer 134. In a manner
23 similar to that previously described, the minute microprotrusions
24 of semiconducting material allow the conductor 138 to be in
touching but nonintimate and virtually nonconducting relation-
26 ship with the semiconducting layer 132 thus resulting in an
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~15386)1
1 extrernely high junction resistance between the conductor 138
2 and the pressure sensitive composition layer s~rface 136. .
4 ~lthougll various particulate sizes and layer thick-
nesses are possible in accordance with the invention, it has
6 been found that there is an inverse relationship between the
7 amount of electrical chatter caused by closing or opening the
switch con~acts and the size of the ~olybdenum disulfide
9 particles. Thus, the finer the grain size of the molybdenum
lP disulfide, the smoother the transition from the OFF to the
11 ON state (or vice-versa) of the switch will be. Specifically,
1 it has been found that particle sizes less than one micron
13 and ~referably about .7 microns provide a substantially
1 chatter-free switch transition.
16 Another embodiment of the invention comprises a novel
17 switch apparatus which functions generally as a double-pole,
18 single-throw switch whereby two independent switches are
19 simultaneously actuated, that is, closed, in response to
a single transverse touch force. At least one of the switches
21 may be pressure responsive so that the amount of voltage
22 drop across the switch various inversely to the amount of
23 touch.ng pressure applied against the switch.
24 Referring to FIGURES 6 and 7 the pressure actuated
2S dual switeh apparatus 210 has a support member 212 whieh
26 may be made out of a flexible resilient material such as
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11538~1 ~
1 ¦ a thin sheet of Mylar. The support member 212 has a first
2 ¦ or bottom portion 214 and a second or top portion 216. The
3 first portion 214 and the second portion 216 of the~support
4 member are defined by a fold line 218 along which the second
portion 216 is folded into an overlaying, but spaced apart,
6 relationship relative to the first portion 214.
7 A plurality of conductors are disposed on one side
8 of the support member 212. Specifically, a first conductor
9 220 electrically interconnected to a first terminal 222 is
l.O disposed on the surface of the support member 212 in a first
11 pattern 224. A second conductor 230, electrically coupled
12 to a second terminal 232, is disposed on the top of the support
13 member 212 in a second pattern 234. The first pattern 224
14 and the second pattern 234 of the first conductor 220 and
the second conductor 230, respectively, are disposed on the
16 first portion 214 of the support member 212.
17 A third conductor 240 is electrically interconnected
18 to a third terminal 242 and is disposed on the second portion
19 216 of the support member 212 in a conductor pattern 244
which is the reciprocal or mirror image of the first conductor
21 pattern 224. Finally, a fourth conductor 250 is electrically
22 interconnected to a fourth terminal 252. The fourth conductor
23 250 is disposed across the first portion 214 and onto second
24 portion 216 of the support member 212. The fourth conductor
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~1538~L
1 250 is disposed on the second portion 216 of the support
2 member 212 in a pattern 254 which is the reciprocal, i.e.,
3 mirror image, of the second pattern 234.
41 A semiconductor composition 260 is disposed on top
51 of at least one of the first, second, third or fourtt! conductors.
61 Of course, it will be appreciated thatthe semiconducting
7 ¦ composition 260 may be disposed on top of several of the
8 ¦ conductors. Thus, electrical contact will be made through
9 ¦ the semiconducting composition layer. This effectively
lO ¦ provides a contact resistance between conductors 220 and
11 ¦ 240 so that a resistance is in series with the switch defined
12 ¦ by the conductors 220 and 240.
13 ¦ The semiconducting composition layer 260 may be any
14 ¦ suitable material which is sprayable, screenable or otherwise
15 ¦ of a consistency whlch may be evenly applied to form a smooth
16 ¦ exposed surface covering the conductor as previously described.
17 ¦ A dual pressure actuated switch structure may be
18 ¦ formed by folding the support member 212 along the fold line
19 ¦ 218 so that the second portion 216 is aligned over the first
20 ¦ portion 214 and the pattern portions of first conductor 220
21 ¦ and the third conductor 240 are in transverse alignment and
22 ¦ the pattern portions of the second conductor 230 and fourth
23 ¦ conductor 250 are in transverse alignment. The first and
24 ¦ third conductors comprise the contacts for one switch and
2~ ¦ the other and fourth conductors comprise the contacts for
26 ¦ the second switch.
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1 A spacer 262 is positioned around the conductors
2 between the first portion and the second portion to maintain
the first and third conductors 220 and 240 and the second
4 and fourth conductors 230 and 250 in a normally spaced apart
relationship. In addition, it will be appreciated that the
6 first and second conductors 220 and 230 on the first portion
7 214 and the third and fourth conductors 240 and 250 on the
second portion 216 must be in close lateral proximity to
allow a single transverse force to cause the first and third
1 conductors 220 and 240 and the second and fourth conductors
1 230 and 250 to simultaneously move into electrically conducting
1 relationship.
1 The switch device may be used in an electrical circuit
1 having first and second utilization circuits 264 and 266.
1 The utilization circuits 264 and 266 may be of any suitable
16 circuit configuration such as that described in United States
17 Patent No.s 3,609,203 or 3,796,756.
1 It will be appreciated that the patterns formed by
19 the conductors on the support member may have any configuration
so long as the conductors for the respective two switches
21 are sufficiently close together to allow simultaneous actuation
22 by the finger of an operator. In addition, the support member
23 may be made in two sections with the first and third terminals
24 attached to one support member and the second and fourth
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1153801
1 terminals attached to the second support member.
2 Referring next to FIGURE 8, another embodiment of
3 the invention is shown comprising a first base member 270
4 which may be a flexible Mylar material, a rigid plastic
material or any other suitable nonconducting support member,
6 and a second base or support member 272 in transversely
7 spaced relationship with the first base member 270. A first
8 conductor 274 is disposed on the surface of the first base
member 270. The conductor 274 includes a first contact member
276 with a plurality of interdigiting fingers 278 and a second
11 contact member 280 also with a plurality of interdigiting
12 fingers 282. The first contact member 276 is electrically
13 interconnected to a first terminal 284 and the second contact
14 member 280 is electrically interconnected to a second terminal
16 286. A first utilization circuit 288 may then be electrically
16 coupled between the first terminal 284 and the second terminal
17 286 in the manner previously described in connection with
18 the embodiment of FIGURE 6.
19 A second conductor 290 is likewise disposed on the
surface of the first base member 270. The second conductor
21 290 has a pattern which in one embodiment is a U-shaped
22 pattern disposed around the first conductor 274. As in the
23 previous embodiment the first conductor 274 and the second
24 conductor 290 are laterally displaced on the first base
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1153801
1 member in sufficiently close proximity so that a single
2 transverse touch force will simultaneously actuate the switches
3 respectively including the first conductor 274 and the second
4 conductor 290.
A third conductor 292 is likewise disposed on one
6 surface of the second base member 272 in facing, aligned
7 relationship with the first conductor 274, and a fourth
8 conductor 294 disposed on the same surface of the second
9 base member 272 in facing, aligned relationship with the
l.O second conductor 290. Hence, the first conductor 274 and
11 third conductor 292 comprise the contacts of a first switch
12 and the second conductor 290 and the fourth conductor 294
13 comprise the contacts of a second switch of the present invention.
14 In the preferred embodiment the third conductor 292
is simply an electrically isolated conductive portion on
16 the second base member 272 having a size sufficient to overlay
17 or cover the entire first conductor 274. The fourth conductor
18 294 has a size and shape corresponding to the second conductor
19 290. The first, second, third and fourth conductors 274,
290, 292 and 29~ may be of any appropriate material and may,
21 for example, be a thin layer of sprayed-on silver, a thin
22 layer of copper, or other suitable conductive material.
23 In order to provide a variable contact resistance,
24 a semiconducting composition 296, somewhat similar to that
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1~53~
1 previously described, may be disposed to cover the first
2 conductor 274, the third conductor 292, or on one or both
3 of the second and fourth conductors 290 and 294.
4 In yet another alternative embodiment, the semiconductor
composition layer 296 may be omitted and the third conductor
6 292 provided to be made solely of the semiconductor composition.
7 In such an embodiment, a separate conductive layer such as
8 the silver or copper layer previously described, need not
9 be provided for the third conductor 292.
Finally, a second utilization circuit 298 may be
11 interconnected between the second conductor 290 and the fourth
12 conductor 294.
13 One ac3vantacle Or this latter embodiment is that
14 a plurality of similar dual switch apparatus may be arranged
in a keyboard arrangement with each fourth contact of each
1 separate dual switcil arrangement being interconnected in a
common buss configuration thereby minimizinq the number o~
electrical contacts which must be made to interconnect the
plurality oE dual switches in the keyboard arrangement.
222 Referring next to FIGURE 9, a partial cutaway view
2 of another novel multiple touch switch apparatus in accordance
3 with the invention is shown. This switch is particularly
24 use~ul in generating a chord in response to the application
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1 of a single transverse touching force. The multiple touch
2 switch 310 functionally comprises a plurality of individually
electrically isolated switches grouped in sets of t~o or
4 more. Each such set comprises a chord switch. A plurality
of chord switches is arranged side by side to form a keyboard
6 for the multiple touch switch apparatus 310.
7 Specifically, the multiple touch switch apparatus
8 310 comprises a first support ply 320 which may be made of
9 a rigid plastic insulative material or may be made of a resilientl
deformable material such as Mylar. A plurality of multi-segment
11 conduction plies 322, each representing a separate chord
12 switch comprises four first electrically isolated conductors,
13 e.g., conductors 324, 326, 328, and 330, each representing
14 one pole or contact of the individually electrically isolated
switches 325, 327, 329 and 331, respectively, are then attached
16 or otherwise fixed to the top surface 332 of the first support
17 ply 320. In the embodiment of the invention in which a chord
18 may be generated upon application of a single transverse
19 touch force, the several first electrically isolated conductors
324, 326, 328 and 330, are positioned in sufficiently close
21 lateral proximity to each other so that when an operator's
22 finger is pressed against the multiple touch switch apparatus
23 310, the top surfaces of the several first electrically
2û olated conductors 324, 32t, 328, and 330 can be contacted
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1 to thereby simultaneously close all of the electrically
2 isolated switches 325, 327, 329, and 331 to generate a chord.
3 Although each of the first electrically isolated
conductors 324, 326, 328, and 330 may be a single layer made
of a purely conductive material such as a layer of silver,
6 copper, or other similar conductive material, in the preferred
7 embodiment, each of the first electrically isolated conductors
8 comprises two layers; a conductive layer which is attached
9 to the top of the first support ply 320 and a first semi-
conductor composition layer which is sprayed, silk screened,
11 electrostatically plated, vacuum deposited, or otherwise
12 disposed to form a very thin layer of semiconductor material
13 which covers the entire conductive layer.
14 By way of example, in accordance with this preferred
embodiment, the first electrically isolated conductor 324
16 comprises a first conductive layer 334 on top of which a
17 first semiconductor composition layer 336is disposed by
18 spraying, silk screening or any other suitable method.
19 Each of the first electrically isolated conductors
324, 326, 328, and 330 are laterally spaced apart from one
21 another to provide the necessary electrical isolation.
22 Insulative spacers are not used between the first electrically
23 isolated conductors which comprise a single chord switch
224 so that a smooth transition between one chord and another
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1 chord having either added or deleted notes, can be achieved
2 without "clicking" by simply "rolling" the operator's finger
3 along the surface of the touch switch 310 to make or break
4 contact with one or more of the first electrically isolated
conductors. On the other hand, an insulative transverse
6 spacer is provided to surround each multi-segment conduction
7 ply 322, i.e., each chord switch. For example, in the
embodiment of FIGURE 14, a plurality of sets of individual
electrically isolated switches, one for each chord to be
generated, is disposed on the top surface 332 where each
11 such set of electrically isolated switches is surrounded
by a transverse spacer 338.
1 The multiple touch switch apparatus 310 further comprises
14 a second support ply 344 having a bottom surface 340 on which
a unitary conductive layer 342, common to all chord switches,
1 is attached. The unitary conductive layer 342 may also be
17 a copper or silver layer which is preferably applied by plating,
1 spraying, electrostatic plating or any other suitable technique
19 by which a thin conductive layer may be affixed to the bottom
surface 340 of the second support ply 344.
22 Preferably, although not necessarily, a second
semiconductor composition layer 346 is affixed by spraying,
23 silk screening or the like to the otherwise exposed surface
24 of the unitary conductive layer 342. The resultant structure,
___
26 ___
11538~)1
1 comprising the second support ply 344, the unitary conductive
2 layer 342, and the semiconductor composition layer 346 is
3 then attached by gluing by suitable mechanical atta¢hment
4 or by any other method to the transverse spacer 338 so that
the semiconductor composition layer 346 is juxtaposed trans-
6 versely opposite to and spaced apart from the semiconductor
7 composition layers of the chord switches.
8 The second support ply 344, the unitary conductive
9 layer 342 and the semiconductor composition layer 346 are
1.0 resiliently deformable so that when the operator presses
11 his finger against the multiple touch switch apparatus 310,
12 the second support ply 344 resiliently deforms to force the
13 semiconductor composition layer 346 into an electrically
14 contacting relationship with one or more of the semiconductor
composition layers of one of the several sets of first electricall
16 isolated conductors such as conductors 324, 326, 328 and
17 330.
18 It will be appreciated, therefore, that each of the
19 electrically isolated switches such as the switches 325,
327, 329 and 331 which represent one chord switch perform
21 a separate switching function but that all or a selected
22 number of those switches may be closed in response to the
23 application of a single transverse touching force.
24 By way of illustration of the interconnection of
the switch apparatus 310 of FIGURE 8, a voltage controlled
26 ___
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11538~)1
1 oscillator (VCO) 350 which generates a single high frequency
2 signal, is coupled to a top octave generator 352, well known
3 in the art, which incorporates, Eor example, frequency divider
4 circuitry to generate a plurality of output signals, each
having a different frequency, on one of a plurality of output
6 leads. In order to generate a chord utilizing the above-
7 described multiple touch switch apparatus 310, it is merely
8 necessary to select four notes and thereafter identify the
9 particular frequency of those musical notes. The output
lead from the top octave generator 352 having that frequency
11 is then coupled to one of the first conductive layers of
12 the first electrically isolated conductors 324, 326, 328,
13 or 330. Similarly, the remaining first conductive layers
14 of the first electrically isolated conductors are coupled
to the appropriate output of the top octave generator 352
16 having an output signal with the remaining selected frequencies.
17 Hence, when a transverse touching force is applied to the
18 multiple touch switch apparatus 310, the semiconductor
19 composition layer 346 will be pressed into contact with one
21 or more of the semiconductor composition layers of the first
22 electrically isolated conductors 324, 326, 328 or 330, to
23 thereby couple one or more signals each with a different
frequency, to the unitary conductive layer 342 where those
24 signals are combined and outputted to an amplifier 354 and
23,63 is reafter audibilized by speaker 356.
',
.
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801
1 In the preferred embodiment of the invention, the
2 first electrieally isolated conductor 324 has its conductive
3 layer 334 coupled to the frequency output of the top octave
4 generator 352 having the frequency of the base note of the
~chord. In addition, in order to allow the base note of the
6 chord to be more easily played alone, the first eleetrieally
7 isolated eonduetor 324 is provided to be of a greater width
8 than the remaining first eleetrieally isolated eonduetors
9 326, 328 and 330.
It will be apparent from the above deseription therefore,
11 that if an operator desires to play a chord having four notes
~2 of different frequencies, it is necessary simply to apply
13 a single transverse touching force at a location which will
14 cause the first semiconduetor layer 346 to eontaet eaeh of
the first eleetrieally isolated conductors 324, 326, 328,
16 and 330. If the operator wishes to delete a note from the
17 chord, it is merely necessary for the operator to roll his
18 finger slightly to thereby open one or more of the individual
19 electrieally isolated switehes by releasing the transverse
touehing foree.
21 The multiple touch switch apparatus 310 may also
223 be provided with a single ON/OFF switeh whieh is staeked
in a laminate-like eonfiguration to the afore-deseribed keyboard
24 switeh arrangement. For example, in FIGURE 9, a first ON/OFF
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26 ___
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11538~1
1 switch conductor 360 is disposed over the top surface of
2 the second support ply 344 and a second ON/OFF switch conductor
3 362 is disposed over the bottom surface of a third support
4 ply 364 to face the first ON/OFF switch conductor 360. The
5 first ON/OFF switch conductor 360 and the second ON/OFE`
6 switch conductor 362 are then spaced from one another in
7 a normally open switch configuration by a spacer 366 which
8 may, for example, comprise a rectangularly cross-sectioned
9 strip which is affixed between the second support ply 344
and the third support ply 364.
11 The ON/OFF switch may be coupled between a voltage
12 source 361 and the VCO and the top octave generator. Therefore,
13 unless the keyboard is depressed to close at least one of
14 the chord switches, no power will be supplied to the VCO
or by the top octave generator.
16 In another embodiment of the invention each multi-segment
17 conduction ply 322 of FIGURE 9cor,lprises a single electrically
18 contiguous conductor rather than four electrically isolated
lg conductors. In such a configuration, a touch sensitive single
21 note keyboard may be provided by itnerconnecting each electrically
22 contiguous conductor to a different successive frequency
23 output from a top octave generator such as the top octave
generator 352 shown in FIGURE 9.
24 Referring to FIGURE 10, a dual function, touch-switch
configuration in accordance with the invention has a first
26 ___
',
11538~)1
1 support member 620 made of an insulative material which may
2 be flexible or rigid. The first support member 620 has a
3 top surface 622 on which a first conductor ply 624 is disposed.
4 A second support member 626, also made of insulative
material, is spaced above the first support member 620 by
6 first spacers 628. A second conductor ply 630 is positioned
7 ¦ or otherwise affixed to the bottom surface of the second
8 support member 626 facing but in spaced apart relationship
9 to the first conductor ply 624. The second support member
626 is made of a material which is resiliently deformable
11 so that the second conductor ply 630 can be depressed into
~2 contact with the first conductor ply 624 by the application
13 of a transverse force F. Thus, the movement of the second
14 conductor ply 630 into contact with the first conductor ply
in response to an applied transverse force 632 provides a
16 first touch switch 632.
17 A second touch switch 642 which is also operable
18 in response to the same transverse force F is incorporated
19 by providing a third conductor ply 639 on the top surface
of the second support member 626. A third support member,
21 which is also made of a resiliently deformable material,
22 is spaced above the third conductor ply 634 by second spacers
23 640. A fourth conductor ply 638 is affixed on the bottom
24 surface of a third support member 636 facing, but spaced
___
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1153E~6)1
1 apart from, the third conductor ply 634 in a normally opened,
2 i.e., non-conducting, relationship. The third support member
3 636, and hence the fourth conductor ply 638, is spaSed apart
4 from the third conductor ply 634 by the second spacers 640.
In operation, the application of the transverse force
6 F, which may be applied by simply pressing against the top
7 surface of the third support member 636, causes the third
8 support member 636 and the fourth conductor ply 638 to be
9 resiliently deformed into electrical conducting contact with
the third conductor ply 634 to thereby close the second switch
11 642 coupled between a power source 643 and the power supply
12 input of a utilization circuit 644. As additional transverse
13 touch force F is applied, the second support member, and
14 hence the third conductor ply 34 and the second conductor
ply 630 are resiliently deformed so that the second conductor
16 ply 630 is brought into electrically contacting relationship
17 with the first conductor ply 624 to thereby close the first
18 switch 632 to thus couple an input signal to the utilization
19 circuit 644.
In a basic embodiment of the present invention, the
21 first, second, third, and fourth conductor plies 624, 630,
22 634 and 638, each comprise simply a conductive layer or plate
23 disposed on the appropriate first, second, or third support
24 members 620, 626, or 636.
___
26 ___
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'
'' ,, ' ' '" ' ' ~ '
llS38~)~
1 In an alternative embodiment at least one of the
2 first and second conductor plies 624 and 630 comprises a
3 conductive layer on top of which is disposed a layer of semi-
4 conductor material to thereby couple a resistance in series
with the switch. Similarly, the second conductor ply 630
6 may include a second conductive layer 650 covered by a second
7 semiconductor composition layer 652.
8 It will be appreciated, of course, that one or both
9 of the third and fourth conductor plies 634 and 638 may also
l.O incorporate a semiconductor top surface layer to provide
11 an additional variable resistance across the switch 642.
12 Although the switches 632 and 642 of the present
13 dual function touch switch apparatus previously disclosed,
14 are closed substantially simultaneously, it will be appreciated
that there will, in fact, be a very small delay between the
16 time that the fourth conductor ply 638 contacts the third
17 conductor ply 634 and the time the second conductor ply 630
18 contacts the first conductor ply 624. This very slight delay
19 allows the power to be applied to the utilization circuit
644 prior to application of the input signal to the utilization
21 circuit 644. This allows the various circuit components
22 to be substantially fully powered and thus operational prior
23 to the connection of input signal.
24 It will be appreciated that more than two switches
may be stacked on top of one another in a unitary touch switch
26 ___
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11538~)1
1 apparatus to thereby provide a multi-function touch switch
2 apparatus without departing from the spirit of the present
3 invention. Each such additional touch switch device may
4 be configured in the manner previously described.
Another configuration of the present invention is
6 shown in FIGURE 11 which illustrates a pressure transducer
7 device 410 having a rigid base member 412, a folded flexible
8 base member 414 having a lower portion 416 and an upper portion
9 418, a diaphragm spacer 422, a resilient deformable diaphragm
1.0 424 and a retaining ring 426.
11 Referring more specifically to FIGURE 12, the flexible
12 base member 414 is illustrated in an unfolded configuration
1 having a connector portion 428 extending from the lower circular
14 portion 416 which is attached to the circular reciprocally
1 shaped upper portion 418 by a bridge or hinge region 434.
1 A first conductor 436 is disposed on the flexible base member
17 414 to extend from the connector portion 428 to define a
18 contact pad 440 at a central region of the lower portion
19 416. A second conductor 438 is also disposed on the flexible
base 414 commencing on the connector portion 428 and extending
21 in a semicircular path around the periphery of the lower
2 portion 416 across the hinge or bridge portion 434 and terminating
23 at a central location in the upper portion 418 to define
24 a contact pad 442. The first conductor 436 and the second
25 conductor 438 are electrically insulated from one another .
26 ___
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1~538~1
1 along the surface of the flexible base member 414.
2 The contact pads 440 and 442 and the upper and lower
3 portions 416 and 418 may be of any desired shape. ~owever,
4 both the contact pad 440 and the contact pad 442 must have
a shape and must be positioned on the lower portion 416 and
6 tlle upper portion 418, respectively, so that when the upper
7 portion 418 is folded along a fold line 444, the contact
8 ¦ pad 442 will be transversely aligned with the contact pad
9 440 to allow electrical conduction between the contact pad
10 ¦ 440 and the contact pad 442 when the upper portion 418 is
11 ¦ forced against the lower portion 416.
~2 ¦ In order to provide variations in the potential drop
13 ¦ between the first conductor 436 and the second conductor
14 ¦ 438 in response to variations in the pressure with which
the upper portion 418 is pressed into contact against the
16 ¦ lower portion 416, a first semiconducting composition layer
17 446 is disposed by spraying or the like to cover the first
18 ¦ conductor 436 including the circular contact pad 440. Similarly,
19 ¦ although not essentially, a semiconducting composition layer
20 ¦ 448 is also disposed by spraying or the like to cover the
21 second conductor 438 particularly including the contact pad
22 442.
23 The semiconductor composition preferably is a mixture
24 of molybdenum disulphide, a resin and possibly powdered
26 ___
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l~S3~301
1 carbon which is thinned with a resin thinner to a sprayable
2 consistency. Thus, a very thin layer of the semiconducting
3 composition layer may be disposed on top of the first and
second conductors.
- Referring again to FIGURE 11, the flexible base member
6 which may be made out of a thin (preferably in th~ range
7 of 1/2 to 5 mils) Mylar is folded into a sandwich-like
configuration with the donut-shaped spacer 420 therebetween.
An adhesive material is then disposed on the top and bottom
surface of the spacer 420 with the lower portion 416 and
the upper portion 418 being held with the semiconducting
1 composition covered contact pads 440 and 442 in facing but
1 spaced apart relationship. The bottom surface 428 of the
14 lower portion 416 of the flexible base is also adhesively
1 affixed to the top surface 450 of the rigid base member 412.
1 Thus, the lower portion 416 of the flexible base 414 is maintained
1 in a rigid state by the rigid base 412 while the upper portion
1 418 of the flexible base 414 is transversely movable into
19 contacting relationship with the lower portion 416.
In the embodiment shown in FIGURES 11 and 12 the
2 spacer 420 is positioned to adhesively connect the lower
2 portion 416 and the upper portion 418 of the flexible base
2 414 about the entire periphery or at least a substantial
2 portion of the periphery of the two portions 416 and 418.
2 ___
2 ___
11538~)1
1 In one embodiment, the spacer may be simply double stick
2 tape cut in the appropriate shape.
3 A breathing hole 429 may also be provided between
4 the chamber defined by the spacer 420 and the region outside
the transducer 410.
6 The resiliently deformable diaphragm 424 is next
adhesively attached to the top surface of the diaphragm spacer
8 422 which is adhesively attached to the upper portion 418
9 of the flexible base member. The spacer 422 may be a square
1 or r~ctangular cross section toroidal or donut-~shaped member
1 and may also be cut from double stick tape. Consequently,
1 the peripheral edges of the resiliently deformable diaphragm
1 424 are in spaced relationship to the upper portion 418 of
14 the flexible base member 414. However, in order to assure
that the upper portion 418 is continuously responsive to
16 both increasing and decreasing pressure forces, a central
17 region of the resiliently deformable diaphragm 424 laterally
18 spaced from the edges of the diaphragm spacer 422 is adhesively
19 attached to the top of the upper portion 418 of the flexible
base member 414. Thus, when an increased pressure is exerted
21 against the diaphragm 424, the upper portion 418 will be
22 pressed downwardly until the semiconducting composition covered
2 contact pad 442 is in electrically conducting relationship
24 ¦ with the semiconducting composition covered contact pad 440.
25 ~ ___
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I -36-
llS38~
1 The greater the force exerted against the upper portion 418
2 the less the contact resistance will be between the upper
3 and lower contact pads 442 and 440 and hence the sm~ller
4 the potential drop across the first and second conductors
436 and 438. As the pressure force decreases, the inherent
6 resiliency of the diaphragm 424 which may, for example, be
7 made out of stretchable rubber such as dam rubber, will pull
8 the upper portion 418 in a direction away from the lower
9 portion 416 to thereby increase the contact resistance between
the lower contact pad 440 and the upper contact pad 442 until
11 the force exerted against the diaphragm 424 is sufficiently
1 small that contact between the upper and lo~er contact pads
1 440 and 442 is broken and resistance becomes infinite.
1 The resilient deformable diaphragm 424 preferably
is adhesively held across the top of the diaphragm spacer
1 422 by the retaining ring 426 which is also adhesively attached
1 around the periphery of the diaphragm 424 so that the diaphragm
1 424 is held in a taut or flat configuration between the retaining
1 ring 426 and the diaphragm spacer 422.
2 Referring to FIGURES 13 and 14 an alternative embodiment
2 of the present invention is illustrated comprising a rigid
2 base 412 an alternative flexible base structure 460, a diaphragm
2 spacer 422, a diaphragm 424 and a rigid retaining member
2 426. As in the first embodiment, the bottom surface of a
2 ___
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~1538~
1 lower portion 462 of theflexible base member 460 is adhesively
2 attached to the rigid base 412. In addition, the spacer
3 422 adhesively attaches the diaphragm 424 to the flexible
4 base member 460. A central region of the diaphragm 424 is
then adhesively attached to an upper or flap portion 464
6 of the flexible base member 460.
7 Referring to FIGURE 14, the flexible base member
8 460 has a first generally circular shaped lower portion 462
9 interconnected by a hinge or bridge portion 468 to the generally
circular flap portion 464 which is smaller in diameter than
11 the lower portion 462. A spacer 466 is adhesively attached
12 around the periphery of the lower portion 462. The spacer
13 466 is generally a square or rectangular cross section toroidal :
14 spacer with a central space having an area which is larger
than the surface area of the flap portion 464. Thus, when
16 the flap portion 464 is folded to overlay the lower portion
17 ¦ 462, it will be unattached about its periphery except at
18¦ the hinged portion 468. Thus, the flap portion 464 is freely
9¦ transversely movable about the hinge portion 468 in the region
201 surrounded by the spacer 466.
21¦ In a manner similar to that previously described
22¦ in conjunction with FIGURE 12, a first conductor 470 extends
23 from a connector portion 472 and forms a centrally located
24 contact pad 474 in the first portion 462 of the flexible
2~
::
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" ' - .:
.
1~538~1
1 base 460. A second conductor 476 disposed on the base 460
2 also extends from the connector portion 472 but extends in
3 a path around the periphery of the first portion 462 across
the hinge or bridge portion 468 and forms a contact pad 478
positioned centrally in the flap portion 464. A suitable
6 semiconducting composition layer 480 is disposed to cover
7 at least the contact pad 474 and optionally the contact 478.
8 The conductor pads 474 and 478 are positioned symmetrically
9 on opposite sides of the fold line 486 so that when the flap
1.0 portion 464 is folded over along the fold line 486 the contact
1 paid 478 will be aligned in facing relationship with the
1 contact pad q74.
1 To provide positive movement of the flap portion
14 464, both toward and away from the lower portion 462 of the
1 flexible base in response to increases and decreases in the
1 applied air pressure, the top surface of the flap 464 opposite
17 the surface on which the contact pad 478 is disposed is adhesively
1 attached to the lower surface of the diaphragm at a central
19 location of the diaphragm laterally spaced from the inside
peripheral edge of the diaphragm spacer 422. Thus, the flap
2 portion 464 moves as the resiliently deformable diaphragm
2 424 moves to thereby cause variations in the contact resistance
2 between the contact pad 474 and the contact pad 478 in response
22 to variations in pressure applied against the diaphragm 424.
2 ___
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~ 1153801
1 The pressure transducer in accordance with the present
2 invention may be utilized in any number of devices. However,
3 one particularly advantageous use is in an electronic saxophone-
4 like device 500, such as the one illustrated in FIGURE 15
which has a mouthpiece 502, an air chamber 504, and a pressure
6 transducer 506 disposed in the end of the chamber 504 with
7 the diaphragm facing inwardly toward the chamber 504. A
8 plug 510 is inserted or otherwise sealed in position in the
9 orifice end 508 of the saxophone-like device to riidly hold
the pressure transducer 506 in position. An additional pressure
11 transducer device 512 may also be positioned at the mouthpiece
12 to be pressed with the lips. A connector 514 is interconnected
13 to the connector 428 or 472 (FIGURES 12 and 14 respectively)
1 or to connector 532 in FIGURE 13 to be described hereafter,
of the selected pressure transducer in accordance with the
1 invention. An appropriate electronic tone generating circuit
17 516 is interconnected to the connector 514 so that, for example,
1 the volume of the tone generated by the tone generating circuit
19 516 can be varied in response to variation of air pressure
2 in the chamber 504. Thus, the harder a user blows into the
21 mouthpiece 502 the greater the pressure in the chamber 504
2 and the higher the volume generated.
2 Referring to FIGURE 16, an alternative pressure trans-
2 ducer in accordance with the invention is illustrated.
2 ___
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s3sal
l Specifically, the ~ressure transducer incorporates a first
2 support member 530 which may be flexible or rigid (e.g.,
3 a PC board), a second support member 534, and a connector
4 portion 532 extending from the first support member 530.
A spacer (not shown) is adhesively attached around the periphery
6 of the first support member in a manner similar to that previously
7 described in conjunction with FIGURE 14.
8 Of course, while the first support member 530 and
9 the second support member 534 are shown as separate members,
they may be a single member connected by a hinge portion
ll as in FIGURES 12 and 14 in which case the second support
12 member adhesively attached to the diaphragm pivots about
13 the hinge portion as the diaphragm moves in and out. However,
l because the second support member provides only a shunt support
there is no need to provide a conductive link across the
16 hingein this embodiment as will be subsequently described.
17 Hence, the second support member 534 may be detached from
18 the first support member 530 and the second support member
l9 534 simply adhesively attached to the diaphragm so that the
second support member 534 moves with the diaphragm. A partic-
21 ularly convenient method of accomplishing this is to spray
22 or silk-screen semiconducting material onto the surface of
2 Packlon Tape which is a printable tape produced by 3M
24 Corporation. A circular dot of this semiconductor covered
___
26 ___
.
.
'' ' -: , '
llS38~)1
1 tape is then stuck onto the diaphragm facing the first support
2 member 530.
3 To provide a transducer device according to this
4 shunt embodiment, a first conductor 540 is disposed,on the
surface of the first support member 530 where the first conductor
6 540 includes a first contact member 542 with a plurality
7 of interdigiting fingers 544 and a second contact member
8 546 also with a plurality of interdigiting fingers 548. The
9 interdigiting fingers 544 and 548 are interleaved between
one another in an electrically isolated relationship.
11 A second conductor 550 is disposed on the surface
12 of the second support member 534 so that when the second
13 support member 534 is adhesively fixed to the diaphragm,
14 the second conductor portion 550 will be juxtaposed in transverse
alignment with the first conductor 540.
16 Prior to affixing the second support member to the
1~ diaphragm, a semiconducting composition layer 552 is disposed
18 to overlay the second conductor 550 to thereby provide a
19 contact resistance between the first and second conductors
540 and 550 when those two conductors are depressed into
21 electrically conducting relationship with one another by
22 the movement of the diaphragm. Of course, it will be appreciated
23 that the semiconducting composition layer may be disposed
24 on either the first or the second conductors 540 or 550,
___
26 ___
'
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11538~)~
1 respectively, or alternatively, the second conductor 550
2 may be made entirely from the semiconducting composition
3 material with a separate conductor such as silver or copper
4 eliminated. Of course, if the semiconducting layer is disposed
on the first and second contact members, it is preferable
6 that there be a laterally disposed insulating space between
7 the semiconducting material on the two contact members.
8 It will also be appreciated that the particular interdigiting
9 fingers may be of any shape and may, for example, be disposed
on the surface in a circular arrangement. Thus, in this
11 embodiment the second conductor portion acts as a shunt between
12 the first and second contact members.
13 It will be appreciated that the spacers are preferably
14 the thickness of a piece of commercially available stick
tape and that the Mylar, in the preferred embodiment, is
16 about 3 mils thick. The contact pads may be of any suitable
17 size and shape and may for example be circular with a diameter
18 of about 1/4-1/2 inches. Finally, in the aforedescribed
19 embodiment where the spot of semiconductor tape is stuck
to the surface of the diaphragm, only one o the spacers
21 420 and 422 is required.
22 While specific embodiments of the present invention
23 have been described, it will be appreciated tha various other
24 modifications and laterations may be made without departing
___
26 ___
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1153YOl
1 from the true spirit and scope of the invention. Consequently,
2 it is the object of the claims to encompass all such modifications
6 as fall wit n the true spirit and scope of the invention.
~O
23
26
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