CA1153803A - Pressure sensitive electronic device - Google Patents

Abstract

ABSTRACT
A pressure responsive, variable resistance, analog device has at least one pair of first and second conductors in spaced-apart relationship. A pressure sensitive resistive conductor composition is disposed in a position to interconnect a resistance between the first and second conductors when the resistive conductor composition makes contact with the conductors. The amount of resistance so interconnected varies inversely to the amount of pressure exerted against the resistive composition. The invention may be incorporated as part of a multiple touch switch having either a lateral or vertical configuration. In addition, the invention may be configured as a pressure transducer device with or without a spacer between adjacent components of the device.

Description

17 The present invention relates to pressure sensitive 18 variable resistance devices, and in particular to devices 19 having a thin layer of part;culated 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 is the inability to continuously 25 vary either the volume or the tonal quality of the sound 26 ___ I ~

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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 contact 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.
Pressure sensitive analog switches have been known.
For example, both in Ruben, Patent No. 2,375,178, and Costanzo, 1 Patent No. 3,386,067, analog switches are disclosed which 1 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.
1 However, the resistive layer must be resilient to force the 19 electrodes apart when the compression force is released.
2 Furthermore, the resistive layer depends on macroscopic 2 compaction to increase the number of electrical conductive paths, and ccnsequently, must have a relatively large 2 thickness. Finally, in such devices the resiliency of the 2 sponge-like layer can decrease with use causing a degeneration 25 in operating characteristics.
2 ___ 11538~)3 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 lP inch using molybdenum disulfide particules in the range of 50 to 600 mesh to provide a h gh but finite number of three-12 dimensionally distributed current flow paths through the 13 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 is then permanently positioned and attached between two 17 conducting electrodes. ;
18 In addition to the above-described functional 19 distinction, the structures disclosed by Mitchell require 20 that the semiconducting volume be positioned between two ~ conductors or between a conductor and an insulative plate in 22 intimate contact with either the insulative plate or the con-23 ductors. Such a configuration is fundamentally different from 24 applicant's invention where the semiconducting composition 265 layer must necessarily have at least one contact surface which -11538~)3 1 is not in intimate contact with either a conductor or another 2 semiconducting layer. Such an arrangement takes advantage of ~ 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.
8 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-1 intimate contact with the opposing surface. Depression of the 1 conducting electrode against the surface of the thin semiconductor 1 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-1 conductor layer is made of any suitable particulated semiconductor 19 material held together and to the surface with a binder.
2 A significant advantage of the thin semiconductor layer 21 of the present invention is that the semiconductor material used 22 to form the layer may be combined with a binder and a binder 23 thinner and thereafter sprayed or silk-screened onto the 24 desired surface to form a layer having a thickness as little 2 ___ 2 ___ .

11538~)3 1 as one mil or less. Labor and material costs are thus greatly 2 decreased.
~ In addition to the above advantages, the use of molyb-4 denum disulfide to cover the conductive layers e~fectively 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.
8 The present invention also substantially eliminates 9 the electrical chatter which is inherent in most switches.
10 Consequently, the resultant switch structure is bounceless.

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 conouctor 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 wt-ich 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 ___ 26 ___ , . ' - , .. .

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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 wnich 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 lP 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 20 conductors (contacts) of at least one of the switches so that 21 the resistance across the contact of that switch varies inversely to the amount of force applied.

The present invention comprises pressure responsive 26 analog switches and transducers having a resistance which varies . llS38~3 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 7 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 lP second contact conductors.
11 Other embodiments of the invention include a pressure 12 transducer device and simultaneously actuated multiple switch 13 devices.

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 223 pressure responsive coating positioned between two conductor plates in a spaced relationship.
24 FIGURE 2 is a cross-sectional side view of a 2 bounceless switch apparatus in accordance with the invention.
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11538~3 1 FIGURE 3 is a pressure versus voltage curve 2 illustrating the variations in voltage across the semiconducting ~ 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.
FIGURE 6 is an exploded partial pictorial partial 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 22 perspective view illustrating one chord switch structure in 3 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 ___ 1 FIGURE 11 is an exploded cross-sectional side view 2 of one embodiment of a pressure transducer in accordance with ~ the invention.
4 FIGURE 12 is a top plan view of the flexible base

5 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 2~ used in FIGURE 13 in an unfolded configuration illustrating O another conductor configuration.

DETAILED DESCRIPTION
23 Referring first to FIGURE 1, an analog switch in 24 accordance with the present invention is shown comprising a 25 first conductor plate 50 spaced from a second conductor , ~6 ___ .~

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1 plate 52 by spacer portions 54 to deEine a gap or chamber 60 2 between the first and second conductor plates 50 and 52. At least one of the conductor plates 50 or 52 is resilient so that 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 8 silver or other conductive material sprayed, screened or 9 otherwise applied on the surface of the support sheet 64 0 adjacent the second conductor plate 52. The second conductor plate 52 may comprise a rigid plastic base member 68 with a 12 thin copper surface 70 disposed thereon. Of course, it will 13 be appreciated that the base member 68 may be flexible and 14 the thin surface 70 may be made of silver or other suitable 15 conductive material. A lead 56 and a lead S8 may be coupled 16 to the silver layer 66 and the copper surface 70 respectively 17 to allow for electrical coupling of the analog switch to a 18 utilization circuit.
19 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-25 conductor material may be any suitable composition which is 26 ___ 3~ trade rnc~rk , -10-` ~ ~
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~ ~ 1153803 l sprayable, screenable, or otherwise of a consistency which 2 may be evenly applied to form a smooth exposed surface. For 3 example, the semiconductor material may be molybdenum disulfide 41 particulate having particle sizes on the order of one to ten 51 microns mixed with a binder material such as resin to form a 61 liquid. A resin thinner may be added to give the composition 7 la consistency suitable for spraying. The thin semiconductor 8 ¦layer 62 of the semiconductor material is then sprayed or 9¦ screened on the conductive layer 66 of the support sheet 64 O¦ or on the copper surface 70 on the rigid base member 68. It ¦ will be appreciated, of course, that the semiconductor layer 2¦ may be of any thickness so long as there is an exposed smooth 3¦ semiconductor surface. However, in order to conserve on 4¦ semiconductor material and to minimize surface irregularities 5¦ which may occur when thick semiconductor layers are utilized, 6¦ a thickness on the order of about .OOl inch or less is preferred.
7¦ The spacer 54 may take various forms. For example, 8¦ in one particularly sensitive embodiment shown in Figure l, l9¦ the spacer 54 is simply~an extension of the support sheet 64 201 where the support sheet has been creased about all or a portion 21 of the periphery of the usable portion of the conductive layer 22¦ 66. The crease 20 acts like a spring tending to maintain the 231 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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~ 11538U3 1 enhances the sensitivity of the transducer.
2 It will be appreciated that the configuration of 3 FIGURE 1 is illustrative only. Thus, the semiconductor layer 4 62 may be disposed on one or both of the support sheets 68 5 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 6~ in laterally spaced relationship 8 to the conductor 56.

~O Referring to FIGURE 2, another embodiment of 1 Ithe invention is illustrated for providing a bounceless switch apparatus having a surface contact resistance which 12 varies inversely with a pressure applied normally thereto.

14 ¦Specifically, a bounceless switch apparatus 100 has a first 15 Isupp~rt member 102 which may be made out of ~lylar, a ricid 16 plastic material, or any other suitable nonconductive base 17 material. A first conductor 10~ is disposed on the surface 18 of the support member 102 with a first pressure sensitive 19 composition layer 106 disposed thereon to cover and be in 22o intimate contact with t~e conductor member 10~.

22 JuY~taposed normally opposite to the first pressure 23 sensitive composition layer 106 is an assembly comprising a 24 support member 110, which may be Mylar, rigid plastic, or 25 any other suitable nonconductive material, a conductor -26 ___ 1 ¦ member 12 disposed on one surE.-ce o~ the support :DeD~her 2 110, and a second pressure sensitive composition la~er 11~
~ disposed to cover and be in intimate electrically conducting 4 relationship with the conductor 112. The assembly comprising the second support 110, the second conductor mel~ber 112, and 6 the second pressure sensitive composition layer 114 is 7 positioned in facing relationship with the assembly compris-8 ing the first member 102 to the first conductor n;ember lOq 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 touching relation-12 ship with the exposed surface 116 of the second p~essure 13 sensitive composition layer 114 to thereby clefine 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 24 composition layer 106 and 114 thus has a number of particles which extend outwardly from the mean surface plane of the 26 ___ , 11538~3 1 ¦ respective pressure sensiti~e composition layers 106 and ll~
2 to form micro protrusions of particulate selr,iconducting 3 material. It is these microprotrusions which allow the first and second pressure sensitive composition layers to touch without being in intimate electrically conducting 6 relationship. However, when pressure is applied compressing 7 the two surfaces together, the microprotrusions on the 8 respective pressure sensitive composition layers are depressed 9 toward one another forming more and more electrical contact lP 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 .;hen 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 i5 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 11~ likewise very high thereby making the relative 22 voltage excursions or variation very small.

24 In operation the pressure is applied to compress the respective pressure sensitive composition layers 26 towards one another SQ that the resistance across the ~, -14-., . .

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, . 1153803 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 junction 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 FIGURE 4.
9 Of course it will be appreciated that a threshold

10 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

13 only one of the ccnductors having a pressure sensitive composition

14 layer disposed thereon is shown in FIGURE 5. Specifically, a

15 conductor member 132 is disposed on the top of an insulative

16 support member 130 with a pressure-sensitive composition

17 layer 134 disposed to cover the conductor 132 and be in

18 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 22 in nonintimate but touching relationship with the exposed surface 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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. ~ 1153803 1 ¦ extremely hig~-, junction resistance between the cond~ctor 138 2 and the pressure sensitive composition layer surface 136.

4 Although various particulate sizes and layer thic~-nesses are possible in accordance ~ith the invention, it has 6 been found that there is an inverse relationship between the 7 amount of electrical chatter caused by closing or openin~ the 8 switch contacts and the size of the ~olybdenum disulfide 9 particles. Thus, the finer the grain size of the molybdenum lC disulfide, the smoother the transition from the OFF to the 11 ON state (or vice-versa) of the switch will be. Specificall~, 12 it has been found that particle sizes less than one micron 13 and ~referably about .7 microns provide a su~stantiall~
14 chatter-free switch transition.

16 Another embodiment of the invention comprises a novel 17 switch apparatus which functions generally as a double-pole, ~8 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 touching pressure applied against the switch.
24 Referring to FIGURES 6 and 7 the pressure actuated dual switch apparatus 210 has a support member 212 which 26 may be made out of a flexible resilient material such as . .

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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 ~ first portion 214 and the second portion 216 of the support 4 member are defined by a fold line 213 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 lP disposed on the surface of the support member 212 in a first 11 pattern 224. A second conductor 230, electrically coupled 2 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 1 and the second pattern 234 of the first conductor 220 and 1 the second conductor 230, respectively, are disposed on the 1 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 ___ 26 ___ - . ' ' : ' ~ il5381)3 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 S¦ of at least one of the first, second, third or fourth conductors.
~¦ 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 compo~ition layer. This effectively 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 of a consistency which 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 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 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 8 second portion 216 must be in close lateral proximity to 9 allow a single transverse force to cause the first and third conductors 220 and 240 and the second and fourth conductors 11 230 and 250 to simultaneously move into electrically conducting 12 relationship.
13 The switch device may be used in an electrical circuit 14 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.
18 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 ___ 26 ___ : ~ :

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. 1153803 1 ¦ terminals attached to the second support member.
2 Referring next to FIGURE 8, another embodiment of 3 the lnvention 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 spaced relationship with the first base member 270. A first 8 conductor 274 is disposed on the surface of the first base 9 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 1 member 280 is electrically interconnected to a second terminal 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 26 ___

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1~53~303 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 294 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 ___ 2~ ___ ' .,' ~

j ~ 1153803 1 previously described, may be disposed to cover the first 2 conductor 274, the third conductor 2~2, 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 ~2 conductor 294.
13 One advantage of this latter embodiment ls that 14 a plurality of similar dual switch apyaratus may be arranged in a keyboard arrangement with each fourth contact of each 16 separate dual switch arrangement being interconnected in a 17 common buss configuration thereby minimizing the n~mber o 18 electrical contacts which must be made to interconnect the 19 plurality of dual switches in the keyboard arrangement.

21 Referring next to FIGURE 9, a partial cutaway view 23 of another novel multiple touch switch apparatus in accordance with the invention is shown. This switch is particularly 24 useful in generating a chord in response to the application ___ 26 I ___ , : j:

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11538~3 1 ¦ of a single transverse touching force. The multiple touch 2¦ switch 310 functionally comprises a plurality of individually 3 ¦ electrically isolated switches grouped in sets of two or 4 ¦ more. Each such set comprises a chord switch. A plurality 5 ¦ 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 o~ 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 24 isolated conductors 324, 326, 328, and 330 can be contacted ___ 26 ___ .~ ~

~ 1153803 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 4 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-1~ 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.
lg 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 24 so that a smooth transition between one chord and another ___ 26 _ _ ' ' . ~ 1153803 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 8 embodiment of FIGURE 14, a plurality of sets of individual 9 electrically isolated switches, one for each chord to be lP generated, is disposed on the top surface 332 where each 1 such set of electrically isolated switches is surrounded 12 by a transverse spacer 338.
13 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, 16 is attached. The unitary conductive layer 342 may also be 17 a copper or silver layer which is preferably applied by plating, 18 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.
21 Preferably, although not necessarily, a second 22 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 ___ ~ 115;~803 1 comprising the second support ply 344, the unitary conductive 2 layer 342, and the semiconductor composition layer 346 is then attached by gluing by suitable mechanical attachment 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 0 resiliently deformable so that when the operator presses 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 1 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.
1 It will be appreciated, therefore, that each of the 9 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 2 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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s~soa 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, for 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 g particular frequency of those musical notes. The output lead from the top octave generator 352 having that frequency 1 is then coupled to one of the first conductive layers of ~2 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 or more of the semiconductor composition layers of the first 21 electrically isolated conductors 324, 326, 328 or 330, to 22 thereby couple one or more signals each with a different 23 frequency, to the unitary conductive layer 342 where those 24 signals are combined and outputted to an amplifier 354 and is thereafter audibilized by a speaker 356.
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~ ~ .

11538~3 1 In the preferred embodiment of the invention, the 2 first electrically isolated conductor 324 has its conductive 3 layer 334 coupled to the frequency output of the top octave 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 electrically 7 isolated conductor 324 is provided to be of a greater width 8 than the remaining first electrically isolated conductors 9 326, 328 and 330.
lP It will be apparent from the above description therefore, 11 ¦ that if an operator desires to play a chord having four notes 12 of different frequencies, it is necessary simply to apply 13 a single transverse touching force at a location which will 14 cause the first semiconductor layer 346 to contact each of the first electrically 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 electrically isolated switches by releasing the transverse touching force.
21 The multiple touch switch apparatus 310 may also 22 be provided with a single ON/OFF switch which is stacked 23 in a laminate-like configuration to the afore-described keyboard 24 switch arrangement. For example, in FIGURE 9, a first ON/OFF
2 ___ 2 ___ , -. . . . .

. , . : ~ . . . :
~ ~ :
- ~ ' . ~ 1153~D3 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 SUI face of a third support 4 ply 364 to face the first ON/OFF switch conductor 360. The first ON/OFF switch conductor 360 and the second ON/OFF
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 9comprises a single electrically 18 contiguous conductor rather than four electrically isolated 19 conductors. In such a configuration, a touch sensitive single note keyboard may be provided by itnerconnecting each electrically 21 contiguous conductor to a different successive frequency 223 output from a top octave generator such as the top octave generator 352 shown in FIGURE 9.
24 Referring to FIGURE 1~ a dual function, touch-switch

25~ figuration in accordance with the invention has a first ~' , ~ 1153803 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 1.0 626 is made of a material which is resiliently deformable 11 so that the second conductor ply 630 can be depressed into 12 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 15 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 conduc~or ply 634 on the top surface of the second support me~ber 626. A third support member, 21 which is also made of a resiliently deformable material, 223 is spaced above the third conductor ply 634 by second spacers 2 640. A fourth conductor ply 638 is affixed on the bottom 24 surface of a third support member 636 facing, but spaced 25 ___ -:

26 ___ . . . .
' ~

' . . ., ,' ~, .

~ ~ 3~03 1 apart from, the third conductor ply 634 in a normally opened, 2 i.e., non-conducting, relationship. The third support member 636, and hence the fourth conductor ply 638, is spaced 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 lO ¦ the third conductor ply 634 to thereby close the second switch 1 ¦ 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 15 ¦ ply 630 are resiliently deformed so that the second conductor 16 ¦ ply 630 is brought into electrically contacting relationship 17 ¦ with the f irst conductor ply 624 to thereby close the f irst 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 I ___ ' - ' ~'- ' ~ ', 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 q 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 1.0 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 20 644 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 ___ ~ 115;~803 1 apparatus to thereby provide a multi-function touch switch 2 apparatus without departing from the spirit of the present ~ 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 424 and a retaining ring 426.
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 shaped upper portion 418 by a bridge or hinge region 434.
16 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 9 416. A second conductor 438 is also disposed on the flexible 2~ base 414 commencing on the connector portion 428 and extending 21 in a semicircular path around the periphery of the lower 2 portion 41~ across the hinge or bridge portion 434 and terminating 2 at a central location in the upper portion 418 to define 24 a contact pad 442. The first conductor 436 and the second conductor 438 are electrically insulated from one another 26 ___ .

' ~ 11538~)3 1 ¦ along the surface of the flexible base member 414.
2 ¦ The contact pads 440 and 442 and the upper and lower ¦ portions 416 and 418 may be of any desired shape. However, 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 the 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 lP 440 and the contact pad 442 when the upper portion 418 is 11 forced against the lower portion 416.
12 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 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 ___ . ~ 1153803 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 8 configuration with the donut-shaped spacer 420 therebetween.
9 An adhesive material is then disposed on the top and bottom .0 surface of the spacer 420 with the lower portion 416 and 11 the upper portion 418 being held with the semiconducting 12 composition covered contact pads 440 and 442 in facing but 13 spaced apart relationship. The bottom surface 428 of the 14 lower portion 416 of the flexible base is also adhesively affixed to the top surface 450 of the rigid base member 412.
16 Thus, the lower portion 416 of the flexible base 414 is maintained 17 in a rigid state by the rigid base 412 while the upper portion 18 418 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 21 spacer 420 is positioned to adhesively connect the lower 22 portion 416 and the upper portion 418 of the flexible base 2 414 about the entire periphery or at least a substantial 24 portion of the periphery of the two portions 416 and 418.
___ 26 ___ ~ 1153~103 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 7 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 1.0 or r~ctangular cross section toroidal or donut-shaped member 11 and may also be cut from double stick tape. Consequently, 12 the peripheral edges of the resiliently deformable diaphragm 13 424 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 2~ 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 23 contact pad 442 is in electrically conducting relationship 24 with the semiconducting composition covered contact pad 440.
___ 26 ___ .

11538~)3 1 The greater the force exerted against the upper portion 418 2 the less the contact resistance will be between the upper and lower contact pads 442 and 440 and hence the smaller 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 12 small that contact between the upper and lo~er contact pads 13 440 and 442 is broken and resistance becomes infinite.
14 The resilient deformable diaphragm 424 preferably is adhesively held across the top of the diaphragm spacer 16 422 by the retaining ring 426 which is also adhesively attached 17 around the periphery of the diaphragm 424 so that the diaphragm 18 424 is held in a taut or flat configuration between the retaining 19 ring 426 and the diaphragm spacer 422.
Referring to FIGURES 13 and 14 an alternative embodiment 21 of the present invention is illustrated comprising a rigid .
22 base 412 an alternative flexible base structure 460, a diaphragm 2 spacer 422, a diaphragm 424 and a rigid retaining member 24 426. As in the first embodiment, the bottom surface of a ___ 26 ___ ~ , ' :

~ 1153~103 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 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 l.O circular flap portion 464 which is smaller in diameter than 1 the lower portion 462. A spacer 466 is adhesively attached i around the periphery of the lower portion 462. The spacer 1 466 is generally a square or rectangular cross section toroidal 41 spacer with a central space having an area which is larger 5¦ 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 ~¦ 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~ ___ 26 ___ - ,,~,'. ~ -~ 1~53~03 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 4 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 portion 464 is folded over along the fold line 486 the contact 11 paid 478 will be aligned in facing relationship with the 12 contact pad 474.
13 To provide positive movement of the flap portion 14 464, both toward and away from the lower portion 462 of the flexible base in response to increases and decreases in the 16 applied air pressure, the top surface of the flap 464 opposite 17 the surface on which the contact pad 478 is disposed is adhesively 18 attached to the lower surface of the diaphragm at a central 19 location of the diaphragm laterally spaced from the inside ~0 peripheral edge of the diaphragm spacer 422. Thus, the flap 21 portion 464 moves as the resiliently deformable diaphragm 22 424 moves to thereby cause variations in the contact resistance 23 between the contact pad 474 and the contact pad 478 in response 24 to variations in pressure applied against the diaphragm 424.
___ 26 ___ ... . -, : ~
, .
~ . ~

.

~ ~1538V3 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 rigidly 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) 14 or to connector 532 in FIGURE 13 to be described hereafter, of the selected pressure transducer in accordance with the 16 invention. An appropriate electronic tone generating circuit 17 516 is interconnected to the connector 514 so that, for example, 18 the volume of the tone generated by the tone generating circuit 19 516 can be varied in response to variation of air pressure in the chamber 504. Thus, the harder a user blows into the 21 mouthpiece 502 the greater the pressure in the chamber 504 22 and the higher the volume generated.
23 Referring to FIGURE 16, an alternative pressure trans-24 ducer in accordance with the invention is illustrated.
2~ ___ 26 ___ ~, -,' . . ~ 1153~)3 1 Specifically, the pressure transducer incorporates a first2 support member 530 which may be flexible or rigid (e.g., ~ 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, lP they may be a single member connected by a hinge portion 11 as in FIGURES 12 and ~ 4 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, 14 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 19 534 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 23 Packlon Tape which is a printable tape produced by 3M
24 Corporation. A circular dot of this semiconductor covered 226 ~~~
___ .

I - 11538~3 . , l 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 17 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. ~f 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 ___ ~ _42_ llS3RS)3 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 of 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 Z4 modifications and laterations may be made without departing ___ 26 ___ - llS38V3 1 from the true spirit and scope of the invention. Consequently, 2 it is the object of the claims to encompass all such modifications 7 as fa with~n the true spirit anù scope of the invention.

16~

:

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A pressure responsive transducer comprising:
a base member;
a first contact on the base member;
a second contact in laterally spaced relationship to the first contact on the base member;
a resilient cover having at least one crease formed therein for resiliently spacing at least a portion of the cover above the base member;
a semiconducting layer on the portion of the cover spaced above the base in shunting relationship to the first and second contacts comprising at least a pressure sensitive semiconductor particulate material, the semiconducting layer having an exposed surface disposed in normally spaced relation-ship with the first and second contacts, and semiconducting layer being responsive to an external pressing force for causing the exposed surface of the semiconducting layer to come into electrically shunting relationship between the first and second contacts for providing an electrically resistive junction region between the first and second contacts along the exposed surface, the resistance across the electrically resistive junction region varying in response to variations in the external pressing force.