US3721781A

US3721781A - Pneumatic read head for document cards

Info

Publication number: US3721781A
Application number: US00187491A
Authority: US
Inventors: J Berkman; W Schaffer; R Lagergren; M Ricklefs
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1971-10-07
Filing date: 1971-10-07
Publication date: 1973-03-20
Anticipated expiration: 1990-03-20

Abstract

A pneumatic read head or switch assembly having a row of air reception ports therein into which jetted air may flow after passing through the apertures of a document card, the reception ports being connected with air pressure responsive switches by means of equal length air passages. The switches comprise pistons movable under the influence of air pressure, and the pistons are disposed in a plurality of rows each of which extends parallel with the row of reception ports and spaced sideways therefrom. Each of the pistons is effective on the center of a bar portion of copper cladding for moving the center of the bar portion into contact with another contact, and the bar portion and other contact for each switch is surrounded by bar portions arranged in hexagonal form for providing a column of support around the switch. A rigid backing plate acted on by springs holds the parts of the switch assembly together.

Description

United States Patent [191 Berkman et a1.

[ 51March 20, 1973 [54] PNEUMATIC READ HEAD FOR DOCUMENT CARDS [73] Assignee: lntemational Business Machines Corporation, Armonk, NY.

22 Filed: Oct. 7, 1971 21 Appl.No.: 187,491

[52] U.S. Cl. ..200/46, 200/83 N, 235/6l.ll C, 340/240 [51 Int. Cl. ..H0lh 43/08 [-58] Field of Search.....200/83 R, 83 N, 46; 307/118; 235/6l.1l C, 61.11 R; 340/240 3,193,631 7/1965 Weingarden ..200/46 3,304,386 2/1967 Schlesinger, Jr..... ....200/46 X 3,614,395 10/1971 Harshman .200/46 3,548,162 12/1970 Young et a]. ..235/6l.ll 3,350,518 10/1967 Krakinowski et a]. ..200/83 R 3,571,542 3/1971 Madden ..200/83 N Primary Examiner-Herman J Hohauser Attorney-Keith T. Bleuer et a1.

[ ABSTRACT A pneumatic read head or switch assembly having a row of air reception ports therein into which jetted air may flow after passing through the apertures of a document card, the reception ports being connected with air pressure responsive switches by means of equal length air passages. The switches comprise pistons movable under the influence of air pressure, and the pistons are disposed in a plurality of rows each of which extends parallel with the row of reception ports and spaced sideways therefrom. Each of the pistons is effective on the center of a bar portion of copper cladding for moving the center of the bar portion into contact with another contact, and the bar portion and other contact for each switch is surrounded by bar portions arranged in hexagonal form for providing a column of support around the switch. A rigid backing plate acted on by springs holds the parts of the switch assembly together.

13 Claims, 18 Drawing Figures PATENTFBmmms 372L781 SHEET 1 [1f 7 FIG @W/// H H II I! u H n u n u H I I! I H n H M I [IV/V/H.

JOHN W. BERKMAN RICHARD E LAGERGREN MERLIN J.RICKLEFS 9y WALTER S. SCHAFFER PATENTEUmzomn SHEET 2 or 7 IIIIF WOOOOO 00000000000000 FIG. 2

Pmiminmzom SHEET 8 OF 7 5 65w ooooc 0 O Q Q'Q MU PNEUMATIC READ HEAD FOR DOCUMENT CARDS BACKGROUND OF THE INVENTION The invention relates to pneumatic read heads or switch assemblies particularly useful for reading the apertures in document cards through which jets of air are directed.

DESCRIPTION OF THE PRIOR ART ports in the-read head are connected by means of t passages with the diaphragm portions.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved pneumatic read head or switch assembly for apertured document cards having equal length air passages between air reception ports in the read head receiving air jetted through apertures in the document cards and air pressure responsive switches. It is contemplated that the air reception ports shall extend in a row disposed at right angles to the direction of movement of the document cards and that the switches shall be disposed in spaced rows located parallel with the row of said ports and equidistant from the path of movement of the document cards.

It is another object of the invention to provide an improved switch assembly in a pneumatic read head of this type which includes cladding of electrically conducting material disposed on a film diaphragm, with portions of the film being connected with the air reception ports in the read head so that the cladding is moved into electrical contact with other contacts depending on which of the ports are supplied with air under pressure, with land patterns surrounding the cladding portions that move to make electrical contact for providing a column of support around the individual switches.

It is a further object of the invention to provide an improved construction of a pneumatic read head which includes a plurality of films and plates stacked to form the completed read head, with the stack terminating with a rigid backing plate which is held by spring pressure so as to .hold the layers of the pneumatic read head in substantially uniform pressure relationship with respect to each other.

In a preferred form, the pneumatic read head of the present invention includes a sense head having a row of air reception ports formed therein and below which an apertured document'card may be passed for providing air under pressure into the ports'depending on which apertures exist in a column in a'document card and having equal length air passages in the form of grooves in the upper surface of the sense head which terminate in four rows extending parallel with the row of air reception ports, and the following parts disposed successively and as layers on top of the sense head: a sense head cover having a perforation therethrough corresponding to the termination of each of the grooves in the upper surface of the sense head, a film diaphragm, a cavity board having cylindrical cavities therethrough in which pistons are movably disposed, a film diaphragm having cladding on its upper surface in the form of bars extending just above each of the rows of openings in the sense head cover and also in the form of bar portions forming hexagons that have their centers in alignment with the centers of the openings through the sense head cover, a thin separator having an opening therethrough coaxially disposed with respect to the centers of the hexagonal bar portions on the diaphragm just below, a contact board having a round cladding portion disposed in alignment with each of the openings through the separator just below and having cladding portions in the form of bars forming a hexagonal pattern surrounding each of the round cladding portions so as to provide a column of support along with the bar portions forming the hexagonal figures in the diaphragm, and a backing plate of relatively thick, rigid material forming the upper member of the pneumatic read head. The backing plate is held by means of a pair of springs on opposite ends thereof so as to hold the layers together with substantially uniform pressure on each of the layers.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end view of the read head or switch assembly of the invention positioned over an air plenum;

FIG. 2 is a top plan view of the air plenum together with aplan view of a document card being-moved over the air plenum;

FIG. 3 is a sectional view taken on line 33 of FIG.

FIG. 4 is an exploded view of the read head of the invention showing its component parts including a sense head, a sense head cover, a first diaphragm, a cavity board, a second diaphragm, a separator, a contact board, and a backing plate;

FIG. 5 is a top plan view of the sense head;

FIG. 6 is a top plan view of the sense head cover;

FIG. 7 is a top plan view of the first diaphragm;

FIG. 8 is a top plan view of the cavity board;

FIG. 9 is a sectional view on an enlarged scale taken on line 99 of FIG. 2 showing a piston disposed in one of the cavities of the cavity board;

FIG. 10 is a top plan view of the second diaphragm;

FIG. 11 is a top plan view of the separator;

FIG. 12 .is a bottom view of the contact board;

FIG. 13 is a top plan view of the backing plate;

FIG. 14 is a sectional view taken on line 14-14 of FIG. 13;

FIGS. 15 and 16 are top plan views of modified forms of second diaphragms;

FIG. 17 is a sectional view of modified pressure applying mechanism for use in place of the pistons received by the cavity board; and

FIG. 18 is a top plan view of a part of the modified pressure applying mechanism taken from line l8- I8 of FIG. 17. Y

DESCRIPTION OF THE PREFERRED EMBODIMENT The illustrated document card reading system comprises, in general, a plenum l and a pneumatic read head or switch assembly 12 positioned above the plenum (see FIGS. 1, 2, and 3). A series of document cards 14 each having punched openings 16 therethrough in a plurality of columns 18, which extend transversely to the direction A in which the cards move, may be passed between the plenum 10 and read head 12; and the read head 12 provides electrical output signals which correspond to the particular ones of the openings 16 that exist in the columns 18.

The plenum 10 comprises a casing 20 which has an air supply opening 22 in a lower portion thereof to which any suitable source of air under pressure may be connected. The plenum 20 hasan upper surface 24 which is substantially flat and has a plurality of ports 26 extending into the inner chamber of the plenum 20. The ports 26 are arranged in a row which is at right angles to the direction A of movement of the cards 14; and the spacing of the ports 26 is the same as that of the holes 16 in the card 14, assuming that in any particular column 18, all of the holes 16 exist that may exist. The read head 12 is spaced from the plenum 10 by means of

spacers

28 and 30.

The read head 12 comprises, in generaLa sense head 32, a sense head cover 34, a diaphragm 36, a cavity board 38, a diaphragm 40, a separator 42, a contact board 44, and a backing plate 46 (see FIG. 4).

The sense head 32 (see FIG. 5) constitutes a plate of phenolic material having a row of ports 48a 48x disposed therein. The ports 48a 48x are spaced the same distances as are the openings 26 in the plenum 10, with each of the ports 48a 48x being directly disposed above one of the openings 26. There may be also other ports in the sense head 32 for purposes other than for sensing the apertures 16 in a document card 14; however, these are not important from the standpoint of the present invention.

The sense head cover 34 (see FIG. 6) is provided with openings 50a 50x therethrough which correspond respectively with the openings 48a 48x, a connection being made between the respective openings 50a 50x and the openings 48a 48:: as will be hereinafter described. The openings 50a 50x are disposed in four

rows

52a, 52b, 52c, and 52d which extend at right angles to the direction A of movement of the document cards 14. In particular, the

openings

50b, 50f, 50j, 50n, 50r, and 50v are disposed on the row 52a; the

openings

50d, 50h, 501, 50p, 50t, and 50x are disposed on the row 52b; the

openings

50a, 50c, 50i, 50m, 50q, and 50u are disposed on'the row 52c; and the

openings

50c, 50g, 50k, 500, 50s, and 50w are disposed on the row 52d.

The sense head 32 in its upper surface is provided with a plurality of grooves 54a 54x cut therein. The grooves 54a 54x respectively connect the ports 48a 48x with the openings 50a 50x. The grooves 54a 54x thus respectively have their entrance ends at the ports 48a 48x and have their other or exit ends in coincidence with the ports 50a 50):. Accordingly, the grooves 54b, 54f, 54j, 54n, 54r, and 54v have their exit ends on the row 52a; the grooves 54d, 54h, 54l, 54p, 54t, and 54x have their exit ends on the row 52b; the

grooves

54a, 54c, 54i, 54m, 54q, and 5414 have their exit ends on the row 52c; and the grooves 54c, 54g, 54k, 540, 54s, and 54w have their exit ends on the row 52d. Each of the grooves 54a, 54e, 54i, 54m, 54q, and 54u have the same configuration and are made up of a part a extending in the direction A, a part b extending at a slight acute angle with respect to the part a, a part 0 extending parallel with the part a, and a curved part d connecting the parts a and c. The grooves 54c, 54g, 54k, 540, 54s, and 54w are identical and each comprises a part b connected with a part e that extends parallel with the direction A and a part f connected with the part e by means of a curved part d. The grooves 54b, 54f, 54j, 54n, 54r, and 54v are identical with the grooves 54c, 54g, 54k, 540, 54s, and 54w, but extend in the opposite direction. The grooves 54d, 54h, 54l, 54p, 54t, and 54x are identical with the

grooves

54a, 54a, 54i, 54m, 54q, and 54a, but extend in the opposite direction. All of the grooves 54a 541: are the same in length since each of these grooves contain the parts b and d and since the sum of the lengths of the parts a and 0 equals the sum of the lengths e andf. The groove portions a and c are of substantially the same length, while the groove portions 2 are substantially longer than the groove portionsf. It will be noted that the groove portions e on opposite sides of a centerline C on which the ports 48a 48x are disposed are in alignment in the-direction A; that the groove parts a are in similar alignment on opposite sides of the centerline C and that the parts c and f are similarly in alignment on opposite sides of the centerline C. It will also be noted that the ports 50a 50x are of relatively small cross-sectional size compared to the cross-sectional size of grooves 54a 541: and that the ports 50a 50x each has a countersunk outlet portion 55 (see FIG. 9). The ports 50a 50x thus act as air restrictions but the countersunk portions 55 assure a relatively large area of air pressure application.

The diaphragm 36 (see FIG. 7) is simply a thin, flexible film which fits over the sense head cover 34. The cavity board 38 (see FIG. 8) is a relatively rigid board of phenolic material, for example, which has round cavities 56a 56x therethrough respectively corresponding to and in alignment with the openings 50a 50x in the sense head cover 34. The cavity board 38 is also provided with a pair of

elongate openings

58 and 60. A button or piston 62 having a boss 62a on its upper surface is slidably disposed in each of the cavities 56a 56x (see FIG. 9).

The diaphragm 40 (see FIG. 10) is of relatively thin, flexible sheet material and is provided with copper cladding in the form of straight segments which provide hexagons 64a 64x that respectively have their centers in alignment with the openings 56a 56x in the cavity board 38. The cladding is also in the form of elongate straight lines or

bars

66a, 66b, 66c, and 66d which are respectively in alignment with the

centerlines

52a, 52b, 52c, and 52d.

The separator 42 (see FIG. 11) is of thin material and is provided with openings 68a 68x therethrough which are respectively in alignment with the centers of the hexagons 64a 64x.

The contact board 44 is of relatively rigid electrical insulating material and is provided on its lower surface with copper cladding in the form of round dots 70a 701: which have their centers in alignment with the centers of the openings 68a 68x respectively (see FIG. 12). Each of these dots 70a 70x is connected to a contact pin 72 for the purpose of completing an electric circuit. It will be noted that the cladding on the contact board 44 and particularly the lines of connection of the circular cladding portions 70a 70): to the pins 72 is of such configuration as to form hexagonal cladding portions 74a 74x, and these hexagonal cladding portions are disposed in substantial alignment with the cladding portions forming the hexagons 64a 64x, respectively.

The backing plate 46 see FIGS. 12' and 13 is of relatively thick material and may be phenolic, for example. The backing plate is provided with

elongated slots

76 and 78 therethrough, and the pins 72 project upwardly into the slots. The backing plate 46 is held fixed with respect to the sense head 32 by means of screws 80, with the remaining parts 34 44 being held captured between the plate 46 and the head 32; the springs 82 are provided around the screws 80 so that the springs are held together under spring pressure. The matching hexagonal cladding patterns on the diaphragm 40 and contact board 44 form in effect columns of support around the corresponding switches, particularly the parts of the cladding at the centers of the hexagons 64a 64x, so as to prevent the copper cladding on the diaphragm 40 from being held in the openings 68a 68:: in the separator 42 by the pistons 62 because of too much clamping pressure from the backing plate 46.

The elongate straight line 664 of cladding on the diaphragm 40 is provided with a contact point 84 which is held in contact by any suitable means with a contact point 86 formed of the copper cladding on the contact board 44 and connected with one of the contact pins 72. This connection allows an electric circuit to be completed from the pin 72 connected with the point 86 and any of the other pins 72 in accordance with the particular piston 62 that has air pressure applied to it by means of the diaphragm 36.

In operation, air under a low pressure, such as l pound/square inch, is discharged into the plenum l0 and .tends to jet through the ports 26. if a document card 14 located between the plenum l0 and the read head 12 at the'tim'e has an aperture 16 located between a port 26 and one of the ports 48a 48x, air under pressure travels through the corresponding groove 54a 54x, through the corresponding opening 50a 50x and into contact with the portion of the diaphragm 36 located just above the opening 50a 501. The corresponding piston 62 located in the corresponding opening 56a 56): moves upwardly and moves its boss portion 62a into contact with the diaphragm 40 and flexes the portion of the cladding bar portions 66a 660 located in the corresponding hexagon 64a 64x so as to move this bar portion through the corresponding opening 68a 68x in the separator 42 into contact with the corresponding circular contact portion 70a 70x thus completing an electric circuit through the circular contact portion to the corresponding pin 72. The ports 48a 48:: are small in diameter at their lower ends relative to the upper parts of the ports and to the connected grooves 54a 54):, as may be seen from FIG. 9, and thus function to prevent undue turbulence in the correspondmg grooves 54a 54x and in the upper relatively large diameter parts of the ports 48a 48x so as to prevent bounce of the pistons 62 with corresponding unreliable switch contact and reading of apertures 16.

Although the portions of the cladding defining the hexagon portions 64a 64x is preferred for spacing purposes, these hexagon defining cladding lines may be dispensed with if desired, relying on only elongate line portions corresponding to the portions 66a 66d for the purpose of completing the electric circuits. A diaphragm 40A or this type is illustrated in FIG. 15 and includes the connected elongate lines of cladding 66aa, 66kb, 66cc, and 66dd.

The diaphragm 40 may be replaced if desired by a diaphragm 403 (see FIG. 16) having copper cladding thereon which is in the form of connected circles 84a 84x. The peripheries of the circles 84a 84x respectively take the place of the hexagons 64a 64.x, and the circles 84a 84:: function in substantially the same manner as the hexagons 64a 64x. The peripheries of the circles and the hexagons function as uniform spacers; and the central portions of the circles and the cladding lines 66a 66d function in a similar manner completing the respective electric circuits.

If desired, the cavity'board 38 and the pistons 62 may be replaced by a thin metal sheet 88 and a separator 90. The sheet 88 is provided with a plurality of hinged plates 92a -.92x which are respectively disposed over the openings 50a 50x. An arcuate slot 94 separates each of the plates 92a 92x from the rest of the sheet 88, and a hinge portion 96 connects the plate to the rest of the sheet 88. Each of the plates 92a 92.1: is provided with a central raised dimple 98. The separator is provided with openings a 100x therethrough in alignment with the corresponding hinged plates 92a 92x and hexagons 64a 64x. This embodiment of the invention functions in substantially the same manner as described in connection with the first-mentioned embodiment, with the hinged plates 92a 92x being acted on by the diaphragm 36 and particularly the portions of the diaphragm 36 located beneath the hinged plate portions 92a 921:, for the purpose of moving the dimple 98 on the hinged plate into contact with the diaphragm 40 for the purpose of making the corresponding electrical contacts.

The above-described pneumatic read head advantageously allows the use of a very low operating pressure, such as l pound/square inch, of air supplied to the plenum 10 while yet providing a reliable reading of the apertures 16 in document card 14. It is only necessary for the pistons 62 or the parts 92a 92x to move through a slight distance so as to engage the cladding on the diaphragm 40, 40A or 403 with contact board 44 in order to complete the electrical circuits corresponding with the particular ports 48a 48x to'which jets of air are supplied from the ports 26 through apertures 16 in a document card 14. The

grooves 54a 54x are all of the same length since each ofthem includes a rounded portion d and an acutely extending portion 12 in addition to parts a and c or parts e andfextending in the direction A which add together to the same length. The response to air jetting through the apertures 16 in a card 14 is thus the same insofar as the time of application of air pressure to a piston 62, for example, with respect to the time of application of air to the corresponding ports 48a 482:. Thus, reliable reading of the apertures 16 in document cards 14 is obtained even though the cards 14 are passed across the ports 48a 48x at very high speeds.

The hexagon shaped cladding 64a 64x on the diaphragm 40 advantageously provides a proper spacing between the diaphragm 40, the separator 42 and the round contact cladding parts 70a 70x on the contact board 44, although, as above mentioned, the hexagon shaped cladding portions 640 64x may be dispensed with, if desired. The upper countersunk portions 55 ofthe ports 50a 50x advantageously provide a relatively large area of air application on the diaphragm 36, even through the ports 50a 50:: in themselves act as relatively small diameter air restrictions. The ports 26 and ports 48a 48x likewise are relatively small in diameter and act as air restrictions to increase the reliability of reading by the read head. The backing plate 46 is relatively thick and stiff; and, acting in conjunction with the springs 82, the plate 46 holds the parts of the read head together with a uniform pressure over substantially all of the parts between the sense head 32 and the plate 46.

The pneumatic read head 12, although providing the reliability of an elastic diaphragm switch, nevertheless is a relatively low cost construction.

We claim:

1. A pneumatic switch assembly for reading document cards having columns of apertures therein, comprising:

a sense head member having a plurality of air reception ports on a face thereof across which the documentcards may be passed so that air may be jetted through the card apertures into said ports,

an air pressure responsive piston corresponding to each of said ports,

means forming a cavity in which each of said pistons is disposed and each cavity having an air entrance opening, some of said ports being located at different distances with respect to their corresponding cavity openings than others of said ports,

electric switch means actuated by each of said pistons when air under pressure is supplied to the piston, and

means providing air passages which connect said cavity openings with the respective ones of said air reception ports, at least some of said passages having bends in them to be longer than the shortest distance between said corresponding ports and openings and so that all of said passages are of the same length.

2. A pneumatic switch assembly as set forth in claim 1, said air passages for most of their lengths constituting grooves formed in a face of said sense head member opposite to said face having said air reception ports therein.

3. A pneumatic switch assembly as set forth in claim 2, each of said grooves having a portion extending in the same direction as the direction of movement of said document cards and also having a portion extending in the opposite direction.

4. A pneumatic switch assembly as set forth in claim 3, said air reception ports and said cavities having their axes extending in the same direction and said ports being disposed in a row, some of said cavities being disposed in a pair of rows that are parallel with said row of air reception ports with one of the rows of cavities being located more remotely from the row of air reception ports than the other said row of cavities.

5. A pneumatic switch assembly as set forth in claim 4, each of said grooves including a groove portion in the form of a half circle connecting said two groove portions extending in the direction of card movement and opposite thereto and also including a slantwise extending groove portion extending at an acute angle with respect to the direction of card movement.

6. A pneumatic switch assembly as set forth in claim 5, said slantwise extending groove portion being connected directly with the corresponding air reception port and with a first one of said two groove portions extending in the direction of card movement and opposite thereto, said groove in the form of a half circle connecting the second one of said two groove portions extending in the direction of card movement and opposite thereto with said first such groove portion.

7. A pneumatic switch assembly as set forth in claim 6, said two rows of cavities being disposed on one side of said row of ports, and others of said cavities being disposed on the other side of said row of ports and being connected with the corresponding ones of said air reception ports with grooves of the same length and of the same type located in said sense head member as said grooves connecting said two first named rows of cavities with the corresponding ones of said air reception ports.

8. A pneumatic switch assembly as set forth in claim 7, said first groove portion extending in the same or opposite directions with respect to card movement for each said cavity of said outermost pair of rows of said cavities being longer than said second groove portion for the same groove and extending in the same or in the opposite direction with respect to card movement.

9. A pneumatic switch assembly as set forth in claim 8, said first and second groove portions extending in the same or opposite directions with respect to card movement for each cavities of said innermost pair of rows being of substantially the same length.

10. A pneumatic switch assembly for reading document cards having columns of apertures therein comprising: means providing on a face of the switch assembly a row of air reception ports across which the document cards may be passed so that air may be jetted through the card apertures into said row of ports,

an air pressure responsive piston means connected to each of said ports, and

electric switch means actuated by said piston means when air under pressure is supplied thereto and including a flat-faced film diaphragm having contact portions carried on the flat face thereof corresponding to each of said piston means, said switch means also including a flat-faced contact board having a contact portion disposed on the flat face thereof opposite to each of said first named contact portions,

either said film diaphragm or said contact board on the flat face thereof being provided with a land pattern of cladding ringing the contact portion carried thereon for forming a column of support around the contact portion.

11. A pneumatic switch assembly as set forth in claim 10, the other of said contact board or film diaphragm also being provided with a land pattern ringing the contact portion thereon for cooperating with said firstnamed land pattern so as to provide a column of support around said contact portions.

12. A pneumatic switch assembly for reading document cards having columns of apertures therein, comprising:

a sense head having a row of air reception ports on a face thereof across which the document cards may be passed so that air may be jetted through the card apertures into said row of ports,

a film diaphragm overlying said sense head,

means for providing an air passage connecting each of said air reception ports with a portion of said diaphragm so that the diaphragm acts as a piston portion for each of said ports,

a sheet containing a plurality of movable piston parts therein each coaxially disposed with respect to the piston portions in said diaphragm,

switch means for each of said piston parts and including a film diaphragm carrying electric contact portions and also including a contact board having a contact portion for each of said first-named con- 2 tact portions for completing an electrical circuit when said contact portions are moved into contact with flexing of the diaphragm,

a separator sheet disposed between said secondnamed film diaphragm and said contact board and having an opening therethrough corresponding to each of said first-named contact portions,

a rigid backing plate overlying said sense head, said sheet containing said movable piston parts, said film diaphragms, said separator sheet, and said contact board, and

spring means effective on said backing plate so as to maintain substantially the same pressure over said sense head, said film diaphragm, said sheets, and said contact board.

13; A pneumatic switch assembly as set forth in claim 12, and also including a sense head cover disposed between said sense head and said first-named film diaphragm and having an opening therethrough corresponding to each of said piston portions, said sheet containing said movable piston parts constituting a cavity board having a plurality of cavities therethrough and said piston parts each constituting a separate piston disposed in one of said cavities.

(5?) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3.721.781

Dated -g on 1 Q7;

Inventofls) J. W. Berkman, R. E. Laqerqren. M. J, Ricklefs and W. S. Schaffer It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected 'as shown below:

In the specification:

Column 5, line 20, "the" (third occurrence) should be -and-.

line 22, "springs" should be --parts--.

line 57, "660" should be -66d.

In the claims:

Column 8, line 42, "cavities" should be --said caVity-.

Column 9, line 3, after "pattern", insert of cladding-r.

si ned and sealed this 2nd day of April 197i.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. Attesting Officer c. MARSHALL DANN- Commissioner of Patents eme Q W105) I UNITED STATES PATENT OFFICE fi (5 7 CERTIFICATE OF

CORRECTION Patent No

3,7 1,731 Dated March on 1 on Invencor(s) J. W. Berkman, R. E. Laqerqren. M. J. Bicklefs and W. S. ,Schaffer It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected -as shown below:

In the specification: I

Column 5, line '20, "the" (third occurrence) should be --and.

line 22, "springs" should be --parts-.

line 57, "66c" should be 66d-.

In the claims I I Column-8, line 42, "cavities" should be said caVity.

Column 9', line 3, after "pattern", insert of cladding-r.

Signed and sealed this 2nd day of April 1971 (SEAL) I Y Y Attest:

EDWARD M.FLETCHER,JR. C. MARSHALL DANN- Attesting Officer Commissioner of Patents

Claims

1. A pneumatic switch assembly for reading document cards having columns of apertures therein, comprising: a sense head member having a plurality of air reception ports on a face thereof across which the document cards may be passed so that air may be jetted through the card apertures into said ports, an air pressure responsive piston corresponding to each of said ports, means forming a cavity in which each of said pistons is disposed and each cavity having an air entrance opening, some of said ports being located at different distances with respect to their corresponding cavity openings than others of said ports, electric switch means actuated by each of said pistons when air under pressure is supplied to the piston, and means providing air passages which connect said cavity openings with the respective ones of said air reception ports, at least some of said passages having bends in them to be longer than the shortest distance between said corresponding ports and openings and so that all of said passages are of the same length.

10. A pneumatic switch assembly for reading document cards having columns of apertures therein comprising: means providing on a face of the switch assembly a row of air reception ports across which the document cards may be passed so that air may be jetted through the card apertures into said row of ports, an air pressure responsive piston means connected to each of said ports, and electric switch means actuated by said piston means when air under pressure is supplied thereto and including a flat-faced film diaphragm having contact portions carried on the flat face thereof corresponding to each of said piston means, said switch means also including a flat-faced contact board having a contact portion disposed on the flat face thereof opposite to each of said first named contact portions, either said film diaphragm or said contact board on the flat face thereof being provided with a land pattern of cladding ringing the contact portion carried thereon for forming a column of support around the contact portion.

11. A pneumatic switch assembly as set forth in claim 10, the other of said contact board or film diaphragm also being provided with a land pattern ringing the contact portion thereon for cooperating with said first-named land pattern so as to provide a column of support around said contact portions.

12. A pneumatic switch assembly for reading document cards having columns of apertures therein, comprising: a sense head having a row of air reception ports on a face thereof across which the document cards may be passed so that air may be jetted through the card apertures into said row of ports, a film diaphragm overlying said sense head, means for providing an air passage connecting each of said air reception ports with a portion of said diaphragm so that the diaphragm acts as a piston portion for each of said ports, a sheet containing a plurality of movable piston parts therein each coaxially disposed with respect to the piston portions in said diaphragm, switch means for each of said piston parts and including a film diaphragm carrying electric contact portions and also including a contact board having a contact portion for each of said first-named contact portions for completing an electrical circuit when said contact portions are moved into contact with flexing of the diaphragm, a separator sheet disposed between said second-named film diaphragm and said contact board and having an opening therethrough corresponding to each of said first-named contact portions, a rigid backing plate overlying said sense head, said sheet containing said movable piston parts, said film diaphragms, said separator sheet, and said contact board, and spring means effective on said backing plate so as to maintain substantially the same pressure over said sense head, said film diaphragm, said sheets, and said contact board.

13. A pneumatic switch assembly as set forth in claim 12, and also including a sense head cover disposed between said sense head and said first-named film diaphragm and having an opening therethrough corresponding to each of said piston portions, said sheet containing said movable piston parts constituting a cavity board having a plurality of cavities therethrough and said piston parts each constituTing a separate piston disposed in one of said cavities.