US2364706A - Crossbar switch - Google Patents

Description

C GILLINGS ETAL CROSSBAR SWITCH Flled Feb 24 1943 Dec. 1-2, 1944.

IN VENTORS CHARLES GILLINGS LAWRENCE JOHN MURRAY ATTORNEY Patented Dec. 12, 1944 CROSSBAR SWITCH Charles Gillings and Lawrence John Murray,

Liverpool, England, assignors, by mesne assignments, to Automatic Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware Application February 24, 1943, Serial No. 476,898

- In Great Britain May 28, 1942 3 Claims.

The present invention relates to selecting switch mechanisms for use in telephone or like systems, and is particularly concerned with selecting switch mechanisms of the crossbar type in which sets of contacts are arranged in such a manner as to form both rows and columns at right angles to one another.

In one form of such switch there is provided for each of the columns a holding bar member operable under control of an electromagnet, while for each pair of adjacent rows of contact sets there is provided a Selecting or preparing bar member which'carries a number of flexible or flexibly mounted selecting fingers corresponding to the number of vertical columns, and which is operable under control of a pair of electromagnets to move the selecting fingers into position adjacent the contact sets of either of the pair of rows involved.

A IOU-point switch of this kind is provided with ten rows and ten columns of contact sets and with five two-way horizontal selecting bars each of which will carry ten selecting fingers corresponding to the ten vertical holding bars which will be required and at each of the fifty intersection points two sets of contacts will be pro vided. In order to select a given set of contacts the associated horizontal bar will be tWisted in a direction to bring its selecting fingers opposite the contact sets of the particular row of ten in which the required contact set is located and the subsequent operation of the vertical bar common to all the sets of contacts inthe same column as that in which the required contact set is located will operate this contact set due to the fact that this will be the only one in the column having a selecting finger interposed between itself and the vertical bar.

When this contact set has been operated the horizontal bar maybe released, but the contact set operated will remain held from the vertical holding bar. Subsequently a second or further set of contacts can be operated in-similar manner. provided it is in a difierent column to the one already operated, but it may be located on the same row.

.On switches of this type it is .possible that if a horizontal bar is actuated in response to say leased the finger may still remain caught and will not spring into its correct position with rean incoming call at a time when a vertical bar is already operated the selectin finger at the spect to the contact set operating piece so that the operation of the horizontal bar, as far as the column represented by the previously operated vertical bar is concerned, will be ineffective. If this vertical bar is to be used again and is re-operated, it will not be possible to effect the necessary connection at the intersection of the vertical and horizontal bars, between the incoming call and a free outlet. One way of overcoming this trouble which has been proposed is to shape the actuating members of the contact sets so as to permit of the selecting finger moving to' its proper selecting position under the conditions envisaged. It is the object of the present invention to devise an improved arrangement whereby the above-mentioned trouble may be overcome.

According to the invention in each of the holding bars of a crossbar switch mechanism there is provided a plurality of recesses corresponding to the number of selecting bars on the switch and of such dimensions that a holding bar on being operated traps the selecting fingers of all unoperated selecting bar-s in its recesses so that the subsequent operation of a-selecting bar while the holding bar is still actuated will be ineffective as far as the selecting finger at the intersection of such bars is concerned until such time as the holding bar is released when the selecting finger in question can spring to its operated position.

The invention will be better understood from the following description of one method of carrying it into efiect, reference being had to the accompanying drawing comprising Figs. 1-5.

Of these figures Fig. 1 shows a perspective view of part of the mechanism of a known crossbar switch as modified according to the invention, while Fig. 2 shows a fragmentary side elevational view of the mechanism. In both these figures several of the mounting and operating.

members have been broken away for the sake of clarity.

Fig. 3 shows a fragmentary view of two contact set operating pieces to show their mounting with respect to the mounting frame common to all contact sets of a column, while Figs. 4 and 5 show the positions occupied by the vertical holding bar with respect to the contact set opcrating pieces when this bar is respectivel in its normal and operated positions. In all the Figs. 3-5 a selecting finger is shown and is assumed to occupy a normal position.

v and which projects slightly under the mounting plate I2. The vertical holding bar I8 is secured to an L section member I9 one end of which forms an armature for an actuating electromagnet, not shown, but which on energising is adapted to twist the member I9, and so advance the bar I8 towards all spring sets of the corresponding column.

From Figs. 1, 4 and 5 it will be seen that the vertical holding bar I8 is provided with a number of U-shaped recesses corresponding to the number of and directly opposite the selecting fingers in the corresponding column which will be five in the case of a IOU-point switch.

With the holding bar in its normal position the selecting pin I6 is free to swing to a position either between the operating piece I4 or operating piece I5 and the bar I8, according to the particular direction of twist given to the selecting bar I! and will bridge the U-shaped part of the operating piece concerned as shown in dotted line form in Figs. 1 and 2. Hence when the bar I8 is subsequently operated, the selected one of the two contact sets at the intersection of the horizontal and vertical bars involved will be actuated,

but the contact fingers of all other horizontal bars which will be in a normal position will enter the respective U-shaped slots in the vertical bar in a manner as shown in Fig. 5. The operating edge of the bar will enter the U-shaped part of the operating piece of each of the contact sets at these intersections and so will not operate these other spring sets.

If at this stage another horizontal bar is oper-' ated then the selecting finger at the intersection of this horizontal bar and the already operated vertical bar will remain trapped in the U-shaped recess of the bar I8 and cannot therefore move into engagement with the relevant contact set operating piece.

When the vertical bar is released, and assuming that the second horizontal bar is still actuated, the selecting finger concerned will remain in normal position until it disengages from the relevant recess in the vertical bar, any tendency for it to be carried outwardly with the vertical bar due to frictional coupling with a side of the recess being prevented due to the fact that its free end projects under and would then engage with the mounting plate I2. Hence when the bar becomes clear of the selecting finger the latter will spring into position against the turnedvup stop on the contact set actuating member in the particular selected row in-readiness for the o eration of the contact set if the same-vertical bar is re-operated.

From the foregoing description. it will be seen that there is thus no possibility of a selecting finger becoming trapped against the side of a con tact set actuating member due to the actuation of a horizontal bar when a vertical bar is already operated, the selecting finger at the intersection of the two bars in question being securely held untilsuch time as the already operated vertical bar is restored to its normal position.

It will be appreciated that the invention is not limited in scope to the precise crossbar switching mechanism described and also that the terms horizontal and vertical" are applied to the respective bars and magnets, rows and columns for convenience and do not and are not intended to indicate that such bars, magnets, rows and columns are necessarily horizontal and vertical but only to indicate the relationship they would bear to each other if the switch was suitably placed, as of course the switch could be arranged in any desired position.

What we claim as new and desire to secure by Letters Patent is:

1. In a crossbar switch, a preparing bar having a normal position and an operated position, a holding bar having a normal position and an operated position, each of said bars being movable from one of its positions to the other, a member having a normal position and moved to an operated position under the joint control of said bars whenever said'preparing bar is moved to its operated position while said holding bar is at normal and said holding bar thereafter is moved to its operated position before said preparing bar returns to normal, means for restraining said member in its normal position in the event that said holding bar is moved to its operated position while said preparing bar is at normal and said preparing bar thereafter is moved to its operated position before said holding bar returns to normal, and a set of circuit controlling contacts operated by said member whenever said member is in its operated position.

2. A crossbar switch as claimed in claim 1, wherein said last means comprises a recess in said holding bar situated at a point opposite the normal position of said member, whereby, in the event said holding bar is moved to its operated position while said preparing bar is at normal, said member enters said recess, the walls of said recess then preventing movement of said member to its operated position if said preparing bar thereafter should be moved to its operated position.

3. In a crossbar switch, an elongated member having a normal position, a flexible finger supported by said member at right angles to the axis of said member, said member rotatable about its axis thereby to move said finger, a second member having one face parallel and normally adjacent to the plane in which said finger ismoved upon rotation of said first member, a recess in said second member positioned directly opposite said finger when said first member is in its normal position, means for moving said second member toward said finger, said second member efiective to engage and move said finger only if said first member is ofi-normal at the time of such movement of said second member, a set of circuit controlling contacts operated by said finger upon movement thereof by said second member, said recess effective, if said first member is at normal when said second member is moved toward said finger, to partially encompass said finger and thereby prevent subsequent movement of said finger in the event that said first member thereafter is rotated before said second member returns to normal.

CHARLES GILLINGS. LAWRENCE JOHN MURRAY.

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