US2203630A - Annunciator - Google Patents

Description

T. A. KEEN ANNUNCIATOR June 4, 1940.

Filed Oct. 12, 1936 3 Sheets-Sheet 1 June 4, 1940. T A KEEN 2,203,630

ANNUNGIATOR Filed Oct. 12, 1936 3 Sheets-Sheet 2 T. A. KEEN June 4, 1940.

ANNUNCIATOR Filed Oct. 12, 1936 5 Sheets-Sheet 5 Patented June 4, 1940 PATENT OFFICE 2,203,630 ANNUNCIATOR Thomas A. Keen, San Mateo, Calif., assignor to Hannah M. Smith, River Forest, Ill.

Application October 12, 1936, Serial No. 105,222

3 Claims.

My invention relatesin general to electrical switching systems and has more particular reference to an annunciator or signal device, more particularly a device for displaying any selected .2 character by energizing appropriate lamps ar ranged in a panel.

An important object of the present invention residesin utilizing a minimum of lampcontrolling circuits to energize selected lamps in a bank In comprising several rows of lamps in order to outline a desired character on the lamp; a further object being to arrange a pair of adjacent lamps in said lamp bank for simultaneously operating through a single control circuit in order to mini- 15 mize the number of control circuits required to produce desired characters.

Another important object is to provide means whereby numerical characters comprising all of the digits of the Arabic system of numerals may if! be displayed in readily interdistinguishable fashion on an annunciator comprising rows of lamps adapted for selective operation to outline the digits; a further object being to utilize a minimum number of control circuits for energizing the 1.) various lamps required in outlining the digits.

Another important object is to provide an improved circuit switching means whereby simultaneously to energize a plurality of circuits; a further object being to provide an improved multiple circuit control switch for remote control operation.

Another important object is to provide an improved solenoid switch for controlling a plurality of electrical circuits.

Another important object is to provide a neat and exact switch box containing a plurality of circuit controlling switches including the provision of simplified electrical connections within said switch box whereby the same may be utilized m in controlling a bank of lamps to selectively energize desired lamps in said bank for the purpose or outlining a desired character in said bank.

Another important object is to provide an improved mounting for lamps forming a bank of i3 selectively operable lamps; a further object being to provide an attractive casing adapted to function as an annunciator, the casing forming a mounting for the lamps arranged in spaced rows including panel means to facilitate the interconm nection of the lamps in lamp actuating circuits.

Another important object is to provide an improved method of selectively energizing lamps to outline any desired character of the Arabic system of numerals; a further object being to pro- 55 vide for the production of any digit of the Arabic system in utilizing a minimum number of energizing circuits.

These and numerous other objects, advantages, and inherent functions of the invention will become apparent as the same is more fully under- 6. stood from the following description which, taken in connection with the accompanying drawings, discloses a preferred embodiment of the invention.

Referring to the drawings: 10.

Figure 1 is a front view of an annunciator panel embodying my present invention;

Figure 2 is a plan view of the back of the device shown in Figure 1;

Figure 8 is a sectional view taken substantially 15 along the line 3-3 of Figure 2;

Figure 4 is a diagrammatic view of the lamp bank illustrating the manner of selectively energizing the lamps thereof in the production of the digits of the Arabic numeral system; I)

Figure 5 is a schematic diagram of electrical connections and control switches utilized in the selective operation of the lamp panel shown in Figure lfor the production of the digits of the Arabic numeral system in accordance with my 25 present invention;

Figure 6 is a perspective view of a switch box embodying the connection shown in Figure 5;

Figure 'l is a sectional view taken substantially along the line 1-1 in Figure 6 to illustrate the 30 details of a control switch embodying my present invention:

Figure 8 is a top plan view of the switch shown in Figure 'l; and

Figures 9 is a sectional view taken along the all lines 9-9 in Figure '7.

To illustrate my invention, I have shown on the drawings an annunciator system comprising a lamp bank llll embodying a plurality of lamps arranged for selective operation in order to out- 0 line any one of the digits comprising the Arabic numeral system, although it will be apparent that my present invention is not necessarily restricted to the production of the particular char-' acters mentioned. On the contrary, many fea- 4g tures of the present invention may be utilized for the selective reproduction of characters of any sort, although the devices herein illustrated and described'are particularly well adapted for the production of the numerical characters of the 9 Arabic system.

In the illustrated embodiment the lamp bank llll comprises twenty-four lamps L, said lamps being individually identified by the numerals 1 to 24. The lamps L are arranged in six rows with four lamps in each row, since this arrangement permits all of the characters of the Arabic numeral system, and of course, many other characters tobe outlined by energizing selected lamps in the bank. The lamps L are mounted each in a socket I03 which in turn is secured in a panel I05 forming a preferably integral part of a box I01, comprising preferably integral side and end walls,'the top and bottom of the box I 01 being open and the panel I" being disposed in the box substantially midway between the top and bottom thereof. The bottom of the box may be closed in any suitable or preferred fashion. The side and end walls of the box and the panel I05 may be formed conveniently as a casing andI prefer to form the box and panel of aluminum in order to minimize weight. The lamp bases I03 may be of any suitable or preferred form and may be anchored in the partition I05 with the lamp receiving sockets thereof facing toward the upper or front open end of the box, the back of the bases I03 extending on the side of the partition I05 facing the bottom or back of the box.

The lamps L also may be of any suitable or preferred form and when mounted in the bases I03 make electrical contact through connections in said' bases with terminals I09 and II I; there being a terminal I09 and a terminal III on each of the bases I03. The box also contains a connection panel II3 preferably supported on the panel I05 by means of support stems II5, which carry the panel H3 in the box adjacent the open back or bottom thereof so that the panel is readily accessible. The panel II3 carries a plurality of terminals T, there being twenty-four terminals corresponding each with a lamp L, said terminals being identified individually by numerals 1 to 24. There is an additional neutral terminal identified by the letter n.

The terminal I09 of each base I03 is connected electrically by means of a suitable conductor with one of the numerically identified terminals, while the terminals III of all of the bases I03 are electrically connected by means of a suitable conductor with the neutral terminal N; The conductors which thus interconnect the terminals of the bases with the terminals T preferably penetrate through openings II1 formed in the panel H3 and are connected on lugs II9 forming portions of the terminals '1' extending adjacent the openings H1. The back of the box I01 may be normally closed in any suitable fashion in order to protect the terminal panel H3 and I prefer to utilize a preferably sheet metal plate I2I secured at its edges by set screws I25 or other suitable fastening devices upon flanges I25 formed at the marginal edges of the box. The side walls of the box also may be formed with an opening or openings in which may be set'suitable conduit means I21 for leading, from the box, conductors for interconnecting the terminals T in electrical circuits for the controlled operation of the lamps L from a point remote from the lamp bank IOI Each of the bases I03 preferably carries a cylindrical shield I29 in position surrounding the lamp supported in the socket in order to contain and direct the rays of the lamp in a single be produced in the lamp bank may ap-' 'produced. The screen I3I may be secured on the box I01 in any suitable or preferred manner,

the screen preferably being seated at its edges in a groove I33 formed in the edges of the box and'held in placev by means of screws I35 or other suitable fastening elements.

As shown in: Figure 4 of the drawings, the twenty-four lamps L may be selectively energized to outline on the screen I 3i any of the numerals of the Arabic system. The Arabic numeral one, for example, may be produced by energizing any one of the four vertical rows of lamps in the bank Il, but I prefer, for reasons hereinafter set forth, to energize either the lefthand orthe righthand vertical row of lamps in the arrangement shown in Figure 1 and it is preferable to utilize the righthand row comprising the lamps L4, 8, I2, I6, 20, 24 in the arrangement shown in Figure 1. In similar fashion theArabic numeral two may be outlined by energizing the lamps L2, 3, 5, 8, I2, I4, I5, i1, 2|, 22, 23, 24.

The Arabic numeral three may be outlined by energizing the lamps LI, 2, 3, 4, 1, l0, II, I6, 20, 2|, 22, and 23.

The Arabic numeral four may be outlined by energizing the lamps L4, 1, 8, I0, I2, I3, l4, I5, I6, 20, 24.

The Arabic numeral five may be outlined by energizing the lamps L2 3, 4, 6, I0, II, I6, 20, 2|, 22, and 23.

The Arabic numeral six may be outlined by energizing the lamps L2, 3, 5, 9, I0, ll, I3, I6, I1, 20, 22 and 23.

The Arabic numeral seven may be outlined by energizing the lamps LI, 2, 3, l, 8, I2, I6, 20, and 24. g

The Arabic numeral eight may be outlined by energizing the lamps L2, 3, 5, 8, l0, ll, l3, l6, I1, 20, 22 and 23.

The Arabic numeral nine may be outlined by energizing the lamps L2 3, 5, 8, 9, I2, I4, I5, I0, 20, 2|, 22 and 23.

The Arabic numeral zero may be outlined by energizing the lamps L2 3, 5, 8, 9, I2, I3, I6, I1, 20, 22, and 23.

Obviously many characters can be outlined by energizing selected lamps to produce the desired pattern on the screen I3I and my present inven .volved. For example, the lamp L2 is never energized in the production of the characters shown in Figure 4 unless the lamp L3 is also energized, and vice versa. For instance the lamps L2 and L3 are energized together in the production of the numerals 2, 3, 5, 6, 7, 8, 9, and 0, said lamps being inactive during the production of the numerals land 4. Likewise, the lamps L22 and L23 are energized together in the production of numerals 2, 3, 5, 6, 8, 9, and 0, and both lamps remain inactive when the numerals 1, 4, and 7 are being reproduced. In like fashion, lamps Lil and LI are utilized together in producing the numerals 2, 4, and 9 while both said lamps remain inactive when the other numerals are being produced. It will be noted, also, that the lamps Lit and Ltd are energised simultaneously in the production of numeralsl, 3, i, 5, d, 'l, 8, 9, and 0, said lampsboth remaining inactive when the numeral- 2 is being reproduced.

I take advantage of the foregoing circumstances to reducethe number oi lamp controlling circuits required to reproduce any one of the numeral'sets on the screen Ill and although all or the numeralsexcept 1 and 7 require more than nine lamps to be energized in reproducing the same on th screen I", I am able to produce all of the numerals by utilizing only nine lamp controlling circuits.

I accomplish this simplification by intercom necting the lamp pairs'LI-I, LIL-l8, Lit-ll, and LII-2i for simultaneous operatiomthe connection being preferably accomplished on the panel ill by interconnecting the corresponding lamp terminals Pl-l, Tll- -li, Tit-20, and Til-23. This, of course, may be accomplished by suitable jumpers Ill interconnecting the appropriate terminals. With such an arrangement only twenty conductors and a neutral conductor need be connected to the appropriate terminals on the panel H3 to energize all of the twentyfour lamps comprising the bank III. It will be noted, however, that the lamps Lil and LI! are not required in the production of any 0! the character sets illustrated in Figure 4. Consequently, when using the lamp bani: in reproduclng the Arabic numerals, the lamps Li! and Lld may be omitted entirely and no provision need be made for energizing the same. Consequently, but nineteen conductors, including the neutral conductor, need be required for making the connections on the panel Hill. I have, nevertheless, illustrated the lamps LIB and LI. and their corresponding terminals TI! and Til in assembly since these lamps may be needed when the lamp bank is used in producing other characters than the Arabic numerals illustrated in Figure 2. In fact, the lamp Ll9 would be required if it were desiredto reproduce the letter Q on the lamp bani: by energizing the lamps Li, ii, 8, It, It, It, ll, til, 22, and 23 together with the lamps Llil and it. Likewise the lamp Lit might be required in utilizing the lamp bank for the production of the letter K by energizing the lamps LIL-i, t, i, did, it, ll, l8, 2l,23,and M.

In order to selectively energize the lamps required in reproducing the desired characters, I have provided improved switching means adapted to be electrically connected with the terminals for the purpose of selectively connecting the lamps with a suitable sourceot electrical power for energizing the same. Oi. course, any suitable switching arrangement may be employed but I have shown on the drawings switching means oi simple and rugged construction adapted to provide satisfactory, failure-free service over long periods of operation. In the illustrated embodiment, the switching device comprises a plurality of individual circuit controlling switches S, a separate switch 5; being provided for the control of the lamps in producing each character.

If alphabetical characters are to be reproduced, it will of course'be necessary to provide aseparate switch S for each alphabetical character and any additional characters, such as the ampersand, which it may be desired to reproduce in conjunction with the alphabetical characters. In the present embodiment, however, I have shown ten switches S, the same being the number required in reproducing the ten numerical characters shown in Figure l. Each oi the required in producing the'numeral Figure d as heretofore mentioned. tls l however, that the switches B may Mhfirdngdto "control any desired numberfotcirciilta. switches S may be conveniently arranged in a meat, to control nine circuits, the Mme losing the maximum number or lampetter 1;

switches S is adapted, in the illustrated moms.

ll-em shown-in switch box or container I31." preierably anaemia ing a rectangular housing or" sheetmetal on which is or may be provided at one end thereai ill a terminal block I carrying tanni nals C which, in the illustrated embodiment, me eleven in number, identified for convenienceby the numerals 1-9, 0 and the letter a. Allmflw of the switch box In is or may be arranged sn- 1 other terminal block Hi containing, in the illuh trated embodiment, twenty-five conductor-ab iaching terminals, which 101' convenience are identified by the numerals 1-24 and the letter :1. i

As shown in Figure "I, each or the control switches 8 comprises a frame havinga base as adapted for attachment on the bottom of the box I31 by means of the fastening screws 065% or other suitable fastening means. The trams I43 carries an upstanding pin I" centrally thereoi on which is mounted a sleeve element ii en tending upwardly of the pin and carryinga plate iii of insulating material. Means Nil compria ing the operating coll at a solenoid is arranged about the sleeve I48 between the base plate Gill! and the plate I", the solenoid coils, oi course,

Iii

being properly insulated from the trainee and sleeve Idll.

Within the sleeve Hid is mounted tor axially shiitable movement therein a stem Nil adapted to form the armature oi the solenoid Hill. This bit stem has an end abuttingthe end or the pin Ill within the sleeve I49, the other end oi the stern I55 extending outwardly of the upper end of the sleeve in position to carry a plate ld'l prefferably formed of electrical conducting material. The plate I5! is secured to the end of the stem I56 by means of a screw which also serves by means of a washer lti, to electrically connect a conductor I63 with the plate it'll. provided for normally urging the stern liili and the plate I5! in a direction away from the insulating element liil. Said stem means preferably comprises a helical spring 8%. Morement of the plate ilil away from the insulating plate Iii is limited by means of the stop pin I81 which is mounted at one end inthe insulating plate l5! and extends through an opening into the plate I51, said stop pin 6672 having a head adapted to engage the upper side at the plate l5i and limit its outward movement away tram the plate under the influence of the spring ltd. The insulating plate lbi carries a plurality oi switch contacts I69 of any suitable or preferred form and having contacting portions supported on the surface of the plate it'll facing toward the conducting plate Hill. In theiilustrated emloodi merit, I have shown nine switch contacts tilt, the same corresponding with the maximum number oi lamp energizing circuits required in producing the numerical characters illustrated in Figure 4.

Means is lid Iii

apart relationship around the peripheral edges oi-:=the plate Ill. The plate Ill. carries a plurality oi shiitabie switch contacts In arranged circularly In spaced-apart relationship around the It; periphery of the plate I61 in position such that each oi: said contacts I19 registers with a corresponding contact I69. as when the solenoid I69 is in de-energized condition, the spring I66 will maintain the contacts I" out of engagement with the contacts I69. As soon as the solenoid I69 is energized, however, the-stem I66 will be drawn downwardly and into the solenoid against the tension of the spring I66 so that the several shiltable contacts I'll may be brought into engagement with the correspond- Ing contacts I69. 'Each of the-contacts I19 is electrically connected with the plate I61 and hehcewith the conductor I69 which functions as aneutral conductor commonly connected with all oi the contacts I". Each of the contacts I19 comprises a stud axially shiftable in an opening iir'the plate I61 and havingspring means I'll normally urgingthe stud in a direction toward thecorresponding contacts I69 so that when the IE solenoid I69 is energized and ,the'plate I6! is drawn toward the plate I6I, the elements I19 upon engaging the switch contacts I69 may yield and move axially into the plate I51 under the tension of the spring I15. The contacts I19 are so. thus yieldingly urgedupon the contacts I69 by means of the springs I15 whenever the solenoid isactuated.

-;='=0ne end of the solenoids of the several switches S is connected by means of a suitable conductor I means I'll with the neutral conductor terminal 01p on the terminal block I99. The other end oi-each of the solenoids of the several switches Sis connected with one of the numerically identilled -conductor terminals C by means of the Q conductors I 19, the switch solenoids thus being each connectible in a separate operating circuit, each'switch solenoid being'connected to its corresponding numerically identifled connecting terminal C. The neutral terminal Cn may be con- Q nested to one side, by means of a suitable conductor, to a suitable source of electrical power Ibmathe operation of the switches S, and the numerically identified terminals C may each be connected through an individual control switch I! and-suitable conductor means with the other side of: said source of operating power whereby any of=the solenoid switches S may be closed by operrating the corresponding control switch. The neutral or common conductors I69 of the several Q solenoid switches S are or may be interconnected and connected with the neutral terminal An on the panel block III while the conductors III which are connected with the stationary switch contacts I69 may be interconnected in any suitup able fashion with the numerically identified terminals A so that upon energizing any one of the solenoid switches S, all of the numerically identifiedterminals A, which are connected with the contacts I 69 of the solenoid switch, may be elecwtrically connected with the neutral terminal An upon the closure of the solenoid switch contacts M9 and I69. ;-;Numerically identified contacts A may be connected by means of suitable conductors forming 7o: a cable with the corresponding numerically identitiedterminals of the lamp bank IIII. The terminals Tn and An may be connected with the opposite sides'of a suitable power source for energizing the lamps so that upon closure 01 a solenoid switch'a-selected number or the lamps L in In normal condition,

As heretofore pointed out.'I may interconnect I certain of the numerically identified terminals T by'means oi the Jumpers I29 so that but one conductor need extend between an appropriate numerically identified terminal Aoi' the block Ill and a corresponding numerically identified terminal T'on the lamp bank panel H9 in order to energize both of the jumper connected lamps. It

is. however, entirely feasible to omit the jumper I29 and to interconnect the lamp circuits on the panel I by joining appropriate terminals by means of jumpers as indicated in dotted lines at ill in Figure 6. I

In the illustrated embodiment, the contacts I99 of the several switches-S are interconnected with the numerically identified terminals A of the terminal block III so that each of the switches 8 control circuits for energizing the lamps L in the manner indicated in'Figure 4 to producethe numerals of the Arabic system.- Interconnection is preferably accomplished,imaccordance with the schematic diagram of connections forming Figure of the drawings and it will be noted that a plurality of bus conductors B are provided within the cabinet and connected each with a terminal A. These bus conductors B are numerically identified with the numerals 1-24 to correspond with the numerically identified terminals A with which the same are connected. One 01 the bus conductors B is identified by the letter n. Since this neutral conductor is connected with the neutral terminal An, in making the connections illustrated in Figure 5 each of the conductors I69 of the several solenoid switches is connected with the neutral bus conductor Bn.

The switch contacts I69 of the solenoid switch So are connected with the conductors B2, 5, 6, 9,

, I2, I9, I6, I1, and 22 and hence may be connected through the corresponding numerically identified terminals A, and hence may be connected through the corresponding numerically identified lamps so that the lamps necessary in reproducing the Arabic numeral zero may be placed in operation when the solenoid switch S0 is closed.

In like fashion the terminals of the solenoid switches S2, 3, 4, 5, 6, 6, and 9 are connected respectively with the bus terminals B as follows:

Switch Terminal connections A-l, 2, 4, 7, 10, 11, 16, 21, 22 A-4, 7, 8, 10, 12, l3, l4, 16, 24

A-Z, 5,9,10,11, 13,16,17, 22 A-2, 5,8,10, [1,13,16,17, 22 A-2, o, 8, 9, 12, 14, l6, 2], 22

So connected, these switches may be connected to energize the corresponding lamps necessary to produce theArabic numerals 2, 3, 4, 5, 6, 8, and 9,

S-I are connected respectively with'the termi-- nals A-l, 8, I2, I6, and 24 while sevenof the terminals of the switch SI are connected respectively with the terminals A-I, 2, 4, 8, I2,-

o a fimpsc it. and it. All of these connections, of course. 7

may be made within the switch box. I". It will be'apparent; however, that the terminals III of duction of certain types 6! characters it.may be. necessary to utilize more than nine cooperating pairs oi switch contacts Ill and I13 in'the solenoid switches.

actlyarranged and provide means tor. controlling Ithe lamps .of the annuu ciatorv bar' kflzill;conveniently i'romaremote control station: .It is also possible {by utilizing holding s'wiichesior connecting the terminals ALwith the correspond;

I The apparatus herein described may','oi-fcourse,'

ll lem and these will, of course, "be'sugge'sted tw ne particular problem to be met andwlllffall-within ,the present invention. g The apparatus is neatpeiract; -and will; provide positive control of; the Iiampsi-and I-urther' jw'iil furnish satisfactory and reliable se vice-through? ingfterminals T of the severalpanels to be jcon-fi trolled by providing suitable circuit ,sustaining.; means for maintaining selected circuits in operationrin a lamp bank iill 'aiterthe switching mechanism in the box illisTdisconnected;

be used in various ways in order =to meet" th requirements oi any particular annunciatorprob out extended operati m It isthought that the invention numerous changes may be made in'the iorm, con struction, and arrangement of the several pa s without departing from thespirit or scope of the" invention and without sacrificing its'attendant advantages, the forms herein described being prepurposes of demon ferred embodiments'ior the .s-trating the invention.

Letters Patent of the United States is:

plified representation of thejsaid Arabic-numerals; said signalling device comprisingelements.

adapted to be operated to give'alocailzed visual effect, said elements being arranged six hori- I zontal rows of four, eight, of said'elements beingconnected in pairs and providing twenty indecpendently actuable signal units, a plurality oi control switches, one of said switches correspond- This, however. may be readily accom-' pushed by increasing the size of the platesili 1 and ill in order to accommodate additional A I switches where the same are, found necessary. 'Ihedevices of my present invention areex A ansis mfie e ous attendant advantages will understood jfr'om the foregoing description and it -is obviouspthat What-I claim is new and desire to secureby .1. A signalling device for s gnalling Arabic. nu merals'and adapted toprovide an improved. simleg to each of the Arabic numerals. each of said switches having not more than nine contacts adapted to be coincidentally energized upon operation of the switch, conductors extending from the contacts of each switch directly to said signal units and operable when each said switch is actuated to energize said elements in the form of one of the Arabic numerals, said paired elements being disposed with two oiv said pairs centrally located in the top and bottom rows,,a third pair being located in adjacent relationship in an intermediate row,- and a fourth pair being situated in vertically adjacent relationship in a side column.

'2. A signalling device for signalling Arabic numerals and adapted to provide an improved, simpliiied representation of the said Arabic burnerals, said signalling device comprising elements. adapted to be operatedto give a localized visual I 'eflect. said elements being arranged in six horiaontal rows oti'our, eight 0! said elements being connected in pairs and providing twenty inde'-, the lamp circuits to utilize a'sin'gle' switch box ill and the switches contained therein for con? trolling a plurality. oi lamp banks. This may be accomplished by providing switch means for. .j

.con'trol switches, one oi said switches corresponding to each 01' the Arabic num rsn escn oi said .f'switches havingsnot more than nine contacts a adapted to be coincidentally energized upon. op

eratiod'ofthe switch, conductors extending from thecontacts of each switch directly to said signalunit's operabiewhen'each said switch is actuated-toenerg ize Esaid elements in the form oi-'oae.joi. the .Arabic numerals','said paired elements beingj-disposedJ-wlth two 0!. said pairs cen-' lt'rally locatedjin the top andjbottom rows,.a third {pair beln'gfdi slibsd centrally in the third row from s the bottonLanda fourth pair'comprising the secend, an th I ,d "elements from the bottom in the {right hand fsidecolumn.

3. Asignalling device-iorfsig nallihg Arabic nu-v merals and-adapted to provide animproved; sim- 'pliiiedrepresentationioithe sfaid Arabic numerals, said signalling device comprising Yelements adapted-Ito beoperatedxto give a localized visual "edect, saidelements being arranged in 'six' horizontali;rows of tour; eight 01 said elements being connected in pairs and providing twenty independently" actuablesignal. units. a plurality of control ;switches. vone voi said switches correlsponding toeach oithe Arabic numerals. each oi said-switches having not morejthannine contacts adapt d to b q n den a ynersized upon cc- 1 eration of the switch; conductors -extending from the contacts or eachfswitch directly to 'sald signal 'units, andoperable when each sa'i'd switch is actuated to energize said-{elements in the' form. of {one of the Arabic numeralslsaid paired elements being disposed'withgapair oi' adiacentelements in the top row connected forgsimultaneous opera- -tion, a pair of adjacent. element s,v in the bottom row connected i'orsimultaneousoperation, andathirdpair oi. element's'in an intermediate 'row being connected for simultaneous operation.

mouse a.

Images