US3571542A

US3571542A - Fluid logic controlled elastic diaphragm switch matrix with cross point shielding

Info

Publication number: US3571542A
Authority: US
Inventors: Thomas F Madden; Lawrence A Tate; Alfred Weiss
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1969-08-12
Filing date: 1969-08-12
Publication date: 1971-03-23
Anticipated expiration: 1988-03-23

Abstract

The fluid logic controlled elastic diaphragm switch matrix is formed of multiple elastic diaphragms having conductive surface portions in alignment with apertures carried by interspersed rigid sheets with the central elastic diaphragm carrying opposed and insulated conducting surfaces which are grounded when the switch point is open to act as shields. The matrix coordinate input pulses are amplified at each matrix unit to verify proper operation of the switch actuating fluid amplifier.

Description

United States Patent Inventors ThomasF. Madden New Canaan, Conn.; Lawrence A. Tate, Irvington; Alfred Weiss, Ossining, N .Y.

Appl. No. 849,422

Filed Aug. 12, 1969 Patented Mar. 23, 1971 Assignee International Business Machines Corporation Armonk, NY.

FLUID LOGIC CONTROLLED ELASTIC DIAPHRAGM SWITCH MATRIX WITH CROSS POINT SHIELDING 9 Claims, 4 Drawing Figs.

U.S. Cl 200/83, 137/81.5, 235/200, 251/331 Int. Cl FlSc 1/10, l-IOlh 35/34 [50] Field of Search 200/83; 137/81.5; 251/331; 235/201 (lnquired), 137 (Inquired); ZOO/83.8

[56] References Cited UNITED STATES PATENTS 3,492,420 l/l970 Neville et a] 200/8300) Primary Examiner-Robert K. Schaefer Assistant Examiner-William J. Smith Attorney- Sughrue, Rothwell, Mion, Zinn and Macpeak ABSTRACT: The fluid logic controlled elastic diaphragm switch matrix is formed of multiple elastic diaphragms having conductive surface portions in alignment with apertures carried by interspersed rigid sheets with the central elastic diaphragm carrying opposed and insulated conducting surfaces which are grounded when the switch point is open to act as shields. The matrix coordinate input pulses are amplified at each matrix unit to verify proper operation of the switch actuating fluid amplifier.

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FLUID LOGIC CONTROLLED ELASTIC DIAPHRAGM SWITCH MATRIX WITH CROSS POINT SI-IIELDING BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to elastic diaphragm switches and more particularly to a switch matrix employing the same under controlled operation of fluid amplifier means.

2. Description of the Prior Art Elastic diaphragm switches generally consist of an apertured, rigid sheet which may carry on one or more sides elastic diaphragms which sandwich the same. Mechanical or fluid pressure means distort the portions of the diaphragm overlying the apertures to selectively open and close switch contacts formed by a conductive surface of the diaphragm itself and/or stationary contacts within the aperture and spaced from the diaphragm. In the absence of positive actuation, resetting of the movable switch contacts occur, since in the relaxed state, the diaphragm merely extends across the aperture and overlies the same.

Fluidic devices have been employed for performing selective functions under applied fluid signals. Pure fluid amplifiers have their power streams flipped from one output channel to the other in response to the controlled application of control streams which normally impinge the power stream within the interaction chamber and downstream from the power stream inlet nozzle. Such devices have in the past constituted fluid logic elements in which a fluid, which may comprise either a gas or a liquid, flows in a controlled fashion to produce at an output port or channel, a pressure differential which is a function of one or more input control jets. Amplification is obtained in such a fluid device since the power of the control jet is much less than that of the output stream. By means of fluid logic devices, relatively complex circuits have been provided I which are the equivalent of most of the standard electronic circuitry and involve such elements as gates, latches, amplifiers, etc.

One specific form of fluid logic utilizes a so-called Coanda effect in its implementation of bistable elements. In a typical bistable element, a power stream of gas such as air flows through a Y-shaped form. Once the power stream is deflected by a control jet to flow through one of the output arms, it will continue to flow through this arm even after removal of the control jet. The phenomenon that makes the flow attach itself to the walls of the output arms is the"Coanda effect.

SUMMARY OF THE INVENTION This invention is directed to an improved elastic diaphragm switching array with highly effective crosstalk suppression, and which may be readily controlled by compatible fluid logic to produce a fluid logic controlled matrixwhich is simple in construction and in which verification of applied coordinate fluid signals may be readily achieved.

Each diaphragm operated switch array preferably comprises first and second imperforate, elastic diaphragms with rigid sheets interposed therebetween and an underlying rigid contact carrying sheet. Three apertures are carried by each of the intermediate sheets which apertures are in axial alignment with conductive surfaces carried by each of the diaphragms and the rigid contact sheet. The conductive surfaces overlie the apertures with opposed conductive surfaces for one of the apertures on the intermediate diaphragm being insulated from each other but in electrical connection respectively with conductive surfaces for the other apertures. The conductive surfaces of the outer diaphragm and rigid contact sheet are electrically isolated from each other. Certain surfaces are grounded. Applied fluid matrix coordinate signals selectively deform portions of the diaphragms carrying the conductive surfaces in the vicinity of the apertures to close the switch contacts not associated -with those surfaces of the diaphragm connected to ground.

The fluid logic for controlling the elastic diaphragm switches comprises logic blocks or units each having a fluid amplifier including a set output passage and a "reset" output passage with the set passage being split to deliver applied fluid pressure to diaphragm portions overlying the two switch array apertures not associated with the ground connections. The reset output passage of the fluid amplifier directs the power stream to the elastic switch diaphragm portion overlying the apertures associated with the ground contacts. The reset output passage is split to additionally form a feedback passage allowing feedback from the "reset" output passage to a control port on one side of the amplifier interaction chamber. An opposed control port is coupled to a first coordinate fluid pulse control passage. A second coordinate fluid pulse control passage intersects the feedback passage upstream of its control port to deflect the feedback stream from the feedback passage and allow flipping of the amplifier power stream from the reset output passage to the set" output passage if a first coordinate control signal fluid pulse is present in its respective control passage.

The feedback passage is split to allow a portion of the feedback stream to pass normally to a sink. The sink stream is selectively deflected into the first coordinate control stream passage. Thus, amplified coordinate control streams by the feedback flow in respective matrix coordinate control pulse passages downstream of the operating logic unit, verify proper operation of the matrix unit.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a 2X2 fluid logic controlled elastic diaphragm switch matrix of the present invention;

FIG. 2 is an exploded view of one of the elastic diaphragm switch arrays employed in one unit of the matrix shown in FIG. 1;

FIG. 3 is a sectional view of a portion of the upper diaphragm of the switch array of FIG. 2, taken about lines 3-3; and

FIG. 4 is a sectional view of the intermediate diaphragm of the switching array of FIG. 2, taken about lines M.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, FIGS. 2, 3, and 4 refer to an improved elastic diaphragm switch array for use with the fluid logic controlled matrix of FIG. I. The elastic diaphragm switch array or assembly 10 is composed essentially of five components, two elastic diaphragms shown as being rectangular in configuration at 12 and 14, a rigid, imperforate contact sheet 16 and interposed relatively

rigid apertured sheets

18 and 20. In this respect, the

intermediate sheets

18 and 20 may be formed of insulative sheet stock material with sheet 18 being provided with three apertures or openings at 22, 24 and 26 respectively, while sheet 20 carries three similar apertures or

openings

28, 30 and 32 with the apertures being in relative axial alignment with those of sheet 18. That is, opening 22 of sheet 18, for instance, is axiallyaligned with opening 28 of sheet 20.

Outer diaphragm 12 is formed of a nonconductive elastic material such as rubber and carries on its lower surface three

X-conductors

34, 36 and 38 which may carry, as shown by the arrows, appropriate electrical matrix coordinate signals X,, X, and X In the vicinity of the

underlying apertures

22, 24 and 26, the

conductors

34, 36 and 28 are provided with enlarged

conductive surface areas

40, 42 and 44, respectively. When the diaphragm 12 is distended locally in the area of one of the

apertures

22, 24 or 26, a conductive portion of the diaphragm is forced downwardly through the associated aperture of sheet 18. In this respect, turning to FIG. 3, the conductive surface 40 may actually pass completely through the opening 22 of the interposed sheet 18. Thus, normally with the diaphragm 12 in a relaxed state, the perforated sheet 18 acts as a separator to prevent contact between the enlarged conductive surface areas of diaphragm 12 and the conductive surface areas of the underlying diaphragm 14 or rigid contact sheet 16. In this respect, diaphragm 14 carries electrically isolated

conductors

48 and 50. Conductor 48, for instance, has enlarged contact surface areas 52 and 52', FIG. 4, overlying aperture 28 of sheet 20 and underlying aperture 22 of sheet 18. Contact surfaces 52 and 52' are electrically connected by means 46. At the opposite end of conductor 48 an enlarged contact surface area 54 underlies aperture 24. Further, conductor 50 has at its outer end an enlarged conductive surface area 56 on the upper surface of diaphragm 14 and an enlarged bottom conductive surface 56' in direct electrical contact. At its inner end, it carries an enlarged conductive surface portion 58 which lies beneath conductive surface portion 54 formed as a part of conductor 48.

Conductive surface portions

54 and 58 are separated by a strip of electrical insulation material 60 which may, in fact, be a portion of the elastic diaphragm 14. The apertured sheet 20 is, in all respects, similar to sheet 18, and formed of electrically insulating material. Further, the outer and lowermost rigid sheet 16 is similar in construction to

rigid sheets

18 and 20, but is imperforate and in this case, carries on its upper surface, Y-coordinate

conductors

62, 64 and 66. These extend generally at right angles to the

X-coordinate conductors

34, 36 and 38 of diaphragm 12.

Conductors

62, 64 and 66 thus carry coordinate electrical signals Y,, Y and Y as shown by the arrows.

Conductors

62, 64 and 66 also include enlarged conductive surface portions at 68, 70 and 72 which underlie, respectively,

apertures

28, 30 and 32 of sheet 20 and are axially in line therewith. Thus, the enlarged conductive surface portion 68 of conductor 62 for the Y-plane sheet 16 is, for instance, in line with aperture 28 of sheet 20, conductive surface 52 of conductor 48 of the intermediate diaphragm 14, aperture 22 of rigid sheet 18 and enlarged conductive surface portion 40 of diaphragm 12.

Switch operations are achieved by the selective application of fluid or mechanical pressure to pressure points identified by arrows 0,, SH and 0,. For switching the matrix on, fluid pressure is preferably applied at actuating positions 0, and O overlying conductive surface portions 40 and 42 of diaphragm 12. This will deform the

elastic diaphragms

12 and 14 thus establishing electrical contact between

conductive surface portions

40, 52 and 68 and thus matrix coordinate conductors X, and Y,.

Conductive surface portions

44, 56 and 72 complete a second electrical circuit between coordinate conductors X and Y since the conducting surfaces 56 and 56' for intermediate diaphragm 14 are deposited on both sides of elastic diaphragm 14 and self-connected through the same.

Release of fluid pressure (or mechanical pressure) on actuating positions 0, and 0, opens the crosspoints while the application of pressure at actuating position HS deforms a different portion of the

elastic diaphragms

12 and 14. As indicated, matrix coordinate conductor X and matrix coordinate conductor Y of

respective diaphragms

12 and 16 constitute ground leads. Thus, the applied pressure deforms the diaphragm forcing conductive surface portions 42 through aperture 24 of sheet 18 and into contact with conductive surface portion 54 of conductor 48 while the underlying conducting portion 58 of conductor 50 due to localized depression of diaphragm 14 is forced into contact with conductive portion 70 of ground conductor 64 carried by the bottom sheet 16 of the laminate assembly 10. Since conducting

surfaces

54 and 58 are deposited on both sides of the elastic diaphragm 14 with no electrical through connectiontherebetween, the actuation of the switch position SH functions to connect the upper conductive surface 54 to ground conductor 36 and the lower conductive surface 58 to ground lead 64 thus interposing a shield between the X and Y conductors at positions 0, and respectively.

In the elastic diaphragm switch array of FIG. 2, there were employed an outer elastic diaphragm 12 and an inner elastic diaphragm 14, a pair of interposed apertured rigid sheets or plates 18 and and a bottom rigid sheet 16. In a form not requiring double contact crosspoints an even simpler arrangement may be achieved.

Referring next to; FIG. 1, there is shown a 2X2 fluid logic matrix which consists essentially of fluid logic blocks 8,, B B and 3,, each of which carries an associated elastic diaphragm switch array identical in form to that shown at 10 in FIG. 2, as at 10A, 10B, 10C and 1010, respectively. Of course, in actual practice, it is envisioned that the fluid logic control array and the elastic diaphragm switch array will be produced in sheets consisting of a large number of fluid logic elements rather than the individual blocks shown. The sheets of the fluid logic are then meshed with sheets of the elastic diaphragm switch arrays. It is essential only that the output of the crosspoint fluid control elements, that is, blocks 8,, B B and B, match the proper pressure point of the elastic diaphragm switch arrays. In the diagrammatic illustration of FIG. 1, each of the fluid logic crosspoint control elements which are identified at A, B, C and D have three outputs 0,, O and SH. The function of the outputs have been described in conjunction with the elastic diaphragm switch array of FIG. 2.

Since the matrix coordinate signals are in the form of fluidic pulses, each of the blocks is provided with fluid control passages such as passages constituting reset signal passages, shown as extending vertically through the blocks, and Y-coordinate signal passages 102 also extending vertically through the blocks; the passages of respective blocks being aligned with the other, In like manner, each block carries a vertical coordinate fluid pulse signal passage, indicated at 104, for the X-coordinate input signals, the passages extending horizontally and in axial alignment for succeeding blocks of the matrix.

A common source of fluid, such as air, acts as a power stream for input passages I, for each of the fluid amplifier elements A, B, C and D. Each fluid power stream is directed from the input passages 1 into the interaction chamber 106 where it is discharged either into a set" output leg or passage 108 or into a reset" output leg or passage 110. The amplifiers A, B,

C and D may be so configured that the power stream in the absence of control signals, will always flow from the inlet I through the interaction chamber 106 and into a reset passage 110. Each amplifier is provided with opposed control ports downstream of inlet I on respective sides of the chamber, a relatively large control port 112 on one side and a much smaller control port 114 on the other. The control port 114 is coupled directly to the X-coordinate control stream passage 104 through connecting passage 116 known as the X-signal input passage. The large diameter control port 112 is carried by a control passage 118 which splits, one flow portion constituting a reset signal passage 120 which opens up into common reset passage 100 for all of the matrix blocks. The reset output passage or leg 1 10 is itself split to deliver a shielding fluid signal through SH passage 122 while a portion of the flow is directed to FX feedback passage 124. The feedback flow in passage 124 is further split with a portion passing through sink passage 126 to the sink S. Another portion of the feedback flow is delivered through feedback passage 120 to the control passage 118 where it enters the interaction chamber 106 through control port 112.

It is noted that the Y-coordinate signal passage 102 intersects the feedback passage 128 at 130 such that, when fluid signal is present in the Y-coordinate signal passage 102, the feedback power stream within passage 118 is diverted from the control port 112 and forced into the Y-coordinate control signal passage 102 to amplify the Y-matrix control signal, which then passes to the next downstream unit or block.

All of the units 8,, B B and B, are identical for the matrix and a selected crosspoint is energized by simultaneous application of a fluid pressure pulse in both an X-coordinate passage 104 and a Y-coordinate passage 102 for selected X- and Y-coordinates. In FIG. 1, it is assumed for illustration purposes, that all four crosspoints are in the reset state, that is, the power stream emanating from each of the inlets l is passing into the reset leg 110 of the amplifier with pressure being applied at actuating position SH for respective matrix elastic diaphragm switches 10A, 10B, 10C and 10D. The crosspoint control power stream entering at I in the reset state follows the reset" arm or passage 110 of the bistable element, which flow splits into the shield output SH in passage 120 and the FX arm or passage 124, which in turn splits into two passages or arms, a feedback arm or passage 128 and a sink arm 126.

If crosspoint Fi -Y is selected, a pressure pulse as identified by the arrow X is injected into the input passage 104 associated with matrix blocks or units 13 and 13 This pressure pulse will have no effect by itself on any crosspoint which is in the reset state since, in this state, the feedback stream through feedback arm or passage 128 is so adjusted as to be much stronger than the control stream passing through X- input passage 116. Thus, in effect, opposed control streams will be entering the interaction chamber 106 through

control ports

114 and 112 but since the control stream in port 112 is much stronger, the power stream emanating from input I will remain deflected into the reset arm or passage 110. The attenuation of the pressure pulse in the X passage as it is propagated from right to left in FIG. 1 is minimized through amplification of the pulse in arm or passage X The X-coordinate pulse flowing through passage 104 not only passes through control passage 116 to port 114 and into interaction chamber 106, but also enters X passage 132 where it diverts the sink stream passing through sink passage 126 from the sink S, to feed it into the loop passage 132, causing the sink stream to enter passage 104 downstream of passage 116. Thus, in effect, the X pulse is amplified, however, this amplification can only take place if the crosspoint X Y is in a reset" state. If a fluidic sensor is placed in passage 104 downstream of crosspoint X -Y and if it measures the increase in pressure due to diversion of the sink stream from passage 126 into passage 132 and thence into passage 104, the sensing device will successfully act to verify the proper operation of the matrix amplifier switch operator.

In like fashion, in the absence of an X-input pulse, a Y, pressure pulse injected into matrix input coordinate passage will have no effect on the matrix. The amplitude of the Y pulse is maintained to the vertical by diverting the feedback arm flow F in passage 128 into the Y A arm to thus reinforce the Y pulse passing through vertical Y-coordinate passage 102, downstream of the matrix amplifier A. The Y-coordinate pulse can be amplified only if there is a fluid stream in the F arm that is passage 128, and again only if the crosspoint is in the reset state. This amplifying mechanism can also be used in the verification of the proper operation of the matrix in similar fashion to the loop X,, for the X-coordinate passage The simultaneous presence of both X and Y pressure pulses will switch the X -Y crosspoint of the matrix into the set state. The smaller power flow in the X arm, that is passage 116, effects the switching of the power stream from the reset passage 110 to the reset passage 108 while the flow in the feedback passage 120 is diverted from control passage 118, and control port 112, by the Y pulse present in the Y- coordinate passage 102. In effect, control is removed from port 112 while it is applied at port 114. The power stream will flip in bistable fashion from reset passage 110 to set passage 108. In the set" condition, the crosspoint control produces two outputs which apply pressure at actuating positions 0 and 0 for the elastic diaphragm switch array 10A which is identical in form and operation to that of switch array 10 of MG. 2.

Release of a crosspoint is accomplished by injection of a fluid pressure pulse into the reset passage 100. A fluid pulse as shown by arrow R will pass into reset passage 120 creating a control signal at port 112 effectively causing the power stream to flip from set" passage 108 to reset passage 110. The reset pulses reset all crosspoints in the vertical. Since the reset action does not require precisely controlled amplitude and thus the amplitude margin of the pressure pulse is wide, no special provisions for pulse reinforcement are believed necessary. Once reset, the matrix is ready for additional applied X- and Y-coordinate fluid input signals, which will cause selective operation of the elastic diaphragm switch array associated with a respective crosspoint matrix logic. The matrix unit blocks and the elastic diaphragm switch arrays may be formed or configured solid or laminate material such as metal, plastic or the like in conventional fashion, for use with the elastic diaphragms. Matrices of the type shown in FIG. 1 may be manufactured at low cost and provide high reliability, with the fluid logic being quite compatible with the elastic diaphragm switch arrays, since the pressure required to activate the same is obtained directly from the fluid logic control device. Further, the fluid logic is very reliable and able to operate within a wide range of environmental conditions. The elastic diaphragm switch readily provides metallic contact crosspoints inherent characteristics highly desirable for fluid switching application and the production cost is low because of the symmetrical iterative nature of the matrices. Further, the elastic diaphragm switches are highly sensitive so that power requirements to energize the given crosspoint may be maintained extremely low. The crosstalk characteristics of the elastic diaphragm switch contacts are improved thus extending the bandwidth characteristics of the resulting switch arrays.

It should be recognized that the logic of the fluid control or the specific form taken by the elastic diaphragm switch array will vary depending upon system application while maintaining the basic concept of fluidic control set forth with respect to the illustrated embodiment along with crosstalk suppression in the switch itself. The fluidic control switch arrays of the present invention find ready application in communication systems as well as analogue and digital data switching systems. Ready application may be made to the control of analogue computer setup, process control and reading mechanisms for cards or perforated tape. In this respect, perforations in either the card or the-tape may control the activation of the fluidic device in which case, each elastic diaphragm switch is controlled by an electronically independent fluid control device such as amplifiers A, B, C and D in the illustrated embodiment. Since compressed air performs quite capably, and constitutes a low cost pressurized fluid source, it is envisioned that in most cases, the working and control fluid would constitute the same.

We claim:

1. A diaphragm operated switch array comprising first and second relatively rigid, apertured sheets, a first elastic diaphragm interposed between said sheets, a second elastic diaphragm overlying the outside of one of said apertured sheets, and a third rigid, imperforate sheet overlying the outer surface of said other apertured sheet, matrix conductors carried by said first and second diaphragms and said third sheet and having portions extending across said apertures, means for selectively displacing portions of said diaphragms overlying said apertures to complete matrix connections between different coordinate conductors carried by said second elastic diaphragm and said third sheet, means connecting one of said matrix conductors to ground, and means carried by said first diaphragm for selectively shielding other matrix conductors in response to displacement of a. portion of said second diaphragm carrying said one conductor.

2. The diaphragm operated switch array as claimed in claim 1 wherein said first and second apertured sheets carry at least three apertures, said second diaphragm and said third sheet carry matrix conductors in like number to said apertures and said first diaphragm includes conductive surface portions on both sides thereof in electrically coupled fashion and at least partially overlying the two most remote apertures, electrically conductive portions carried on opposed surfaces of said diaphragm and in alignment with said intermediate aperture but electrically insulated from each other, means for connecting respectively, intermediate aperture conductive surfaces to adjacent remote aperture conductive surfaces, and means for grounding the matrix conductor carried by said second diaphragm and said third sheet, whereby; pressure application to said diaphragm in localized areas corresponding to the outermost apertures causes circuit completion between respective matrix coordinate conductors, while pressure application on said diaphragm area associated with aligned intermediate apertures results in shielding of said open circuit matrix conductors on both said second diaphragm and said third sheet.

3. The diaphragm switch array as claimed in claim 2 wherein said third sheet carries matrix conductors in strip form with enlarged surface area portions corresponding to the areas of respective apertures of said first and second sheets, and said first diaphragm includes conductive portions carried on both surfaces of said diaphragm in the vicinity of all three apertures with the surface portions for the central aperture being separated by said diaphragm which electrically insulates the same.

4. A fluid logic controlled elastic diaphragm switch matrix with crosspoint shielding comprising: a plurality of fluid logic matrix units, an elastic diaphragm switch assembly for each matrix crosspoint, each switch assembly comprising at least two elastic diaphragms separated by a rigid apertured sheet, conductive surfaces carried by said diaphragms and adapted to make contact in response to localized deformation of said diaphragm in the vicinity of said apertures, said apertured sheets each carrying three apertures, two of said apertures allowing crosspoint connection, said third aperture effecting individual ground connections to shielding means for each matrix conductor, each matrix unit comprising a fluid amplifier including a power stream inlet, an interaction chamber, set and reset outlet passages at the downstream end thereof, and opposed control ports between the inlet and outlet passages, said set passage being divided to direct a pair of fluid power streams to switching points of said elastic diaphragm switch array associated with said matrix crosspoint conductors, and said reset output passage terminating at said diaphragm overlying said shield aperture.

5. The elastic diaphragm position switch matrix as claimed in claim 4 further comprising feedback means coupled to said reset outlet passage for feeding a portion of said power stream to one of said control ports, and passage means for directing a matrix coordinate fluid pulse to said other control port.

6. The matrix as claimed in claim 5 further comprising a second matrix coordinate control pulse passage intersecting said feedback passage whereby, the presence of a matrix coordinate fluid pulse in said second passage deflects said feedback fluid from said feedback passage into said second matrix coordinate control pulse passage.

7. The matrix as claimed in claim 6 wherein the feedback is larger than the flow of fluid in said first matrix coordinate signal input passage.

8. The matrix as claimed in claim 7 further comprising a reset input signal passage, and means for fluid coupling said reset input passage to said second control port.

9. The matrix as claimed in claim 5 wherein said feedback passage further comprises means for diverting a portion of said feedback flow to a sink, said first coordinate input signal passage includes a loop which intersects said sink whereby; the presence of a matrix coordinate input pulse in said first matrix coordinate-inputpassage causes deflection of sink flow into said loop passage to amplify said first control matrix coordinate input signal, downstream of the fluid amplifier receiv' ing the same.

Claims

1. A diaphragm operated switch array comprising first and second relatively rigid, apertured sheets, a first elastic diaphragm interposed between said sheets, a second elastic diaphragm overlying the outside of one of said apertured sheets, and a third rigid, imperforate sheet overlying the outer surface of said other apertured sheet, matrix conductors carried by said first and second diaphragms and said third sheet and having portions extending across said apertures, means for selectively displacing portions of said diaphragms overlying said apertures to complete matrix connections between different coordinate conductors carried by said second elastic diaphragm and said third sheet, means connecting one of said matrix conductors to ground, and means carried by said first diaphragm for selectively shielding other matrix conductors in response to displacement of a portion of said second diaphragm carrying said one conductor.

9. The matrix as claimed in claim 5 wherein said feedback passage further comprises means for diverting a portion of said feedback flow to a sink, said first coordinate input signal passage includes a loop which intersects said sink whereby; the presence of a matrix coordinate input pulse in said first matrix coordinate input passage causes deflection of sink flow into said loop passage to amplify said first control matrix coordinate input signal, downstream of the fluid amplifier receiving the same.