US3673366A - Crossbar switch - Google Patents

Abstract

A crossbar switch is shown which utilizes a plurality of select units and a plurality of hold unit assemblies mounted on a frame. All of the armatures for the select units are located on one end of the crossbar switch frame, and a plurality of select-offnormal switches are positioned on the opposite end. Each hold unit is composed of a hold armature assembly, a plurality of fixed contacts, a plurality of movable contacts under the control of movable cards and a plurality of select fingers, which in conjunction with the hold armature, translate the selected cards to close the movable contacts which are under the control of the selected card. There is also provided a select finger holder having a plurality of mounting posts which frictionally engage the support member of the hold unit, said holder further including a plurality of mounting buttons for receiving and supporting the select fingers.

Description

United States Patent Symes June 27, 1972 GTE Automatic Electric Laboratories Incorporated, Northlake, Ill.

[22] Filed: Mayltl,197l

[21] Appl.No.: 141,876

[72] inventor:

[73] Assignee:

[52] 0.8. Ci. ..200/l75, 200/1 R, 335/1 12 [SI] ..H0lh 9/00 [58] Field of Search ..200/l R, 166 J, 175, I76, 177; 335/112 {56] References Cited UNITED STATES PATENTS 2,643,299 6/1953 Bellamy ..200/177 3,445,795 5/1969 Holtfreter et al. ..335/112 3,478,285 11/1969 Haines et a1 ..335/1 12 3,509,301 4/1970 De Smet ..200/l75 X Primary Examiner-U. R. Scott Attorney-K. Mullerheim, B. E. Franz and David W. Heid [57] ABSTRACT A crossbar switch is shown which utilizes a plurality of select units and a plurality of hold unit assemblies mounted on a frame. All of the armatures for the select units are located on one end of the crossbar switch frame, and a plurality of selectoff-normal switches are positioned on the opposite end. Each hold unit is composed of a hold armature assembly, a plurality of fixed contacts, a plurality of movable contacts under the control of movable cards and a plurality of select fingers, which in conjunction with the hold armature, translate the selected cards to close the movable contacts which are under the control of the selected card There is also provided a select finger holder having a plurality of mounting posts which frictionally engage the support member of the hold unit, said holder further including a plurality of mounting buttons for receiving and supporting the select fingers.

7 Claims, ll Drawing Figures PATENTEDJUHN I372 3.673 .366

sum 3 or 7 PMEN'I'ED JUN 27 1973 3 6 73 3 6 6 saw u or 7 PMENTEBJUH 2 7 m2 3 6 73.366 SHEET 5 OF 7 FIG. 5

cnossmm SWITCH BACKGROUND OF THE INVENTION ample U.S. Pat. No. 3,366,90] to Keller, issued .Ian. 30, I968 and US. Pat. No. 3,445,795 to Holtfreter et al, issued May 20, I969. The Holtfreter et al crossbar switch is typical of some of the crossbar switches which are presently in use, and in some respects is similar to the crossbar switch disclosed herein. In quite broad tenns, it can be said that the typical crossbar switch is composed of a group of select magnet assemblies and a group of bold magnet assemblies. Interaction between the select assemblies and the hold assemblies closes the desired electrical contacts through mechanical operation of the hold armatures. As might be surmised from the name, the select magnet assemblies precondition or select the desired group of movable contacts to be connected to a corresponding set of stationary contacts, and the hold magnet assemblies close and retain closed the selected contacts.

In the crossbar switch disclosed in the Holtfreter patent, each hold unit assembly includes a plurality of cards each having an aperture in one end through which a select finger is inserted. Each card controls the opening and closing of a number of movable electrical contacts which extend through slots in the card, these movable contacts being mated with stationary electrical contacts supported on the hold assembly. Each select bar includes a plurality of operators, with one operator for each pair of select fingers on the associated switch level. When a select bar is rotated, each operator on that bar moves the corresponding select finger into a restricted area within the card aperture associated with the translated select finger. Thereafter, activation of the hold armature on a hold unit assembly translates the selected cards and thereby closes the movable contacts associated with the selected card. As shown in Holtfreter, each hold unit assembly contains ten cards under a control of five operators which are positioned between five pairs of select fingers. In the Holtfreter patent the sets of select fingers which extend through the cards are mounted on individual mounting posts which were individually affixed to the support plate of the hold unit assembly. Since there were five sets of select fingers, this required affixing five individual mounting posts to each support plate of the hold unit assembly. Five select bars with one each select armature per bar are used and the five armatures for the five select bars are located on alternate ends of the crossbar frame. Consequently, there are three select armatures on one end of the frame and two on the opposite end, all requiring a relatively large amount of space on each end. This spacing of the select armatures on alternate ends of the crossbar frame increased the overall length of the frame, thus increasing the width of the mounting racks which support the crossbar switches.

SUMMARY OF THE INVENTION According to one feature of this invention, there is provided a one-piece select finger holder having a mounting button for each select finger set and a plurality of mounting posts adapted to frictionally engage the support member of the hold unit assembly. The one-piece select finger holder may be molded in a single unit and pressed into place on the support member, thus avoiding the problem of individually mounting a number of buttons on each support member.

According to another feature of this invention, the mounting buttons provided on the unitary select finger holder are substantially semicircular. When a select finger set, which has a generally circular shaped bight therein, is inserted into the groove provided in each button, a portion of the bight remains exposed beyond the button. With this arrangement a damaged select finger set may be easily removed from a button by grasping the exposed portion ofthe bight.

According to an additional feature of this invention, the groove provided in each button is "angled" such that it biases the select fingers into the base portion of the card aperture.

According to another feature of this invention, all of the select armatures are positioned on the same end of the crossbar switch frame and the corresponding electromagnets for each select armature are positioned on alternate sides of the associated frame end plate, resulting in a reduction of overall frame length.

According to still another feature of this invention, the crossbar switch frame includes a member which is channeled to provide increased strength to the frame.

These and other features of the invention will be better understood after a perusal of the detailed description and the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a partial front view of the crossbar switch assembled in accordance with this invention;

FIG. 2 is a top view of the crossbar switch shown in FIG. 1;

FIG. 3 is a view of the right end of the crossbar switch of FIG. I;

FIG. 4 is a view of the left end of the crossbar switch illustrated in FIG. 1;

FIG. 5 is a sectional view taken along section 55 of FIG.

FIG. 6 is an enlarged perspective view of a hold unit with the associated select bars and operate fingers as incorporated in the crossbar switch of FIG. I;

FIG. 7 is an enlarged perspective view of a select finger holder in accordance with the invention, with a portion thereof broken away to show one of the mounting posts incorporated therein;

FIG. 8 is an enlarged perspective view of the select finger holder in accordance with the present invention;

FIG. 9 is a view of the right end of the select finger holder as shown in FIG. 8;

FIG. 10 is an enlarged perspective view of a select finger set used in the hold units; and

FIG. II is a side view of the select finger set illustrated in FIG. 10.

DETAILED DESCRIPTION As shown in FIGS. 1-4, crossbar switch 13 is composed ofa number of hold unit assemblies 14 and a number of select units 15. The select and hold units are supported by a frame which is composed ofa lower plate 16 and an upper plate I7 which are welded to left and right end plates 18 and I9 respectively. Mounting straps 20 and 21, which include mounting holes 30, are welded to the upper and lower frame plates 17 and I6 respectively, and provide facilities for mounting the crossbar switch in a rack-type arrangement.

As can readily be seen in FIGS. I and 2, select bars 52 are supported between end plates 18 and I9 by screws 22 and 23 which are threaded through end plates I8 and 19 respectively. A portion of the uppermost select bar 52 and the corresponding select finger set 27 have been omitted from FIG. 1 to more clearly show cards 39. Each select bar 52 has rigidly attached thereto armatures 24 which are associated with electromagnets 25, which when activated, pivot select bars 52 in the direction of the electromagnet so energized. Each select bar 52 has associated therewith and rigidly attached thereto an operate finger 26 for each hold unit assembly I4. Each operate finger 26 is inserted between a pair of select fingers 27. The operation of this arrangement will be fully described subsequently. At this point it should be noted that in the present crossbar switch 13, all of the select annatures 24 and their corresponding select magnets 25 are located on the same end of the frame, with the select armature 24 and select electromagnets 25 for any one select bar 52 being located on alternate sides of end plate 18. In prior art arrangements such as in U.S. Pat. No. 3,445,795, some of the select armatures and their corresponding electromagnets for the select bars were placed on one end of the frame and the remainder were placed on the opposite end of the frame. However, by placing all of the select armatures 24 and their corresponding electromagnets 25 on the same end of the frame, in the manner illustrated in the drawing, the overall length of the crossbar switch is significantly reduced.

During operation of the crossbar switch, it is desirable to know which, if any, of the select bars 52 have been activated and also in which direction they have been activated.

An indication of which select bar 52 has been rotated and in which direction is provided on crossbar switch I3 by a group of select-off-normal switch assemblies designated 29, which are best shown through FIGS. 1 and 3. One selcct-offmormal assembly 29 is provided for each select bar 52 and is activated by a select-olf-normal pin designated 28. In FIG. 3 it can be seen that select bar 52 which is the second up from the base of the crossbar switch 13 has been operated such that the lower pair of contacts on the selectoff-normal switch 29 has been closed, thus indicating that the upper electromagnet associated with that select bar 52 has been activated. The selectoff-normal assemblies 29 perform a second function in addition to indicating which select bar 52 has been activated. As can best be seen from FIGS. 2 and 3, each select-off-normal switch assembly 29 has a pair of flat springs 31 which extend outward from the assembly, with one spring located on each side of the select-off-normal pins 28. The springs 3i retain the unoperated select bars 52 in a neutral position, as shown in FIG. 3. FIG. 5 illustrates the aforementioned neutral position of the four unoperated select bars 52 and their associated operate fingers 26. The lower spring of pair 31 which is associated with the select bar 52 which has been operated will return this operated select bar 52 to the neutral position once the electromagnet 25 associated with the operated select bar 52 has been de-energized.

In FIGS. 35 it can readily be seen that lower plate 16 in cludes a number of channels which extend the length of the frame. By channeling lower plate 16, additional strength in torsion and deflection is achieved, resulting in a frame more sturdy than a conventional one employing non-channeled members of equal thickness. Thus it can be appreciated that by channeling the frame members, it is possible to achieve the required frame strength using plates of a lesser thickness than that required when only flat frame members are employed.

Now turning to FIG. 6, there is shown an enlarged perspective view of a typical hold unit 14, a portion of the select bars 52 and the operate fingers 26, as used in crossbar switch 13 of this invention. The hold unit 14 is composed of a support member 32, which forms the basic foundation to which the remaining elements of the hold unit are attached. Hold magnet assembly 33 is composed of a motor unit 34, and an armature 35 which extends the length of the hold unit frame, and is pivoted on each end thereof. Armature stop 36 is provided to limit the return travel of the armature 35 produced by return spring 54, after de-energization of motor unit 34. Attached to the opposite side of support member 32 is a series of stationary bars 37 having contacts 53 thereon, and a row of movable contacts 38, the position of which are controlled by cards 39. There is provided a set of movable contacts 38 on each card for each stationary bar 37, consequently, each card 39 controls the opening and closing of six sets of electrical contacts. The stationary bars 37 are spaced apart and supported on the support member 32 by insulating blocks in a snap in arrangement designated 40, and connections to the stationary bars 37 are brought out to the rear of the hold unit 14 by bus members 41 which extend through an insulating block assembly 42 at the rear of the hold unit 14. In a similar manner, movable contacts 38 which are of the fiat spring type, extend through insulating block 42 at the rear of the hold unit 14 and connections thereto may be made at bus members 43. Bus members 41 and 43 can be more readily identified by reference to FIGS. 3 and 5.

FIG. is an enlarged perspective view ofa select finger set 46 of the type used in the present crossbar switch 13. Select finger set 46 is composed of two generally L-shaped fingers 27, joined at a bight portion 47. As can be seen from HG. 10, each select finger 27 is deformed at a point near bight 47 such that when the fingers 27 are free to move, they are tensioned toward each other and in the absence of any restraining force actually cross each other. FIG. I! is a side view of the select finger set 46 as shown in FIG. I l, and at this point it should be noted that the longer portion of the L of each finger is straight as opposed to prior art select fingers which had the corresponding L-portion bent at a predetermined angle. The significance of straight longer portion of select fingers 27 will become more apparent after a further description of bold unit 14.

FIG. 8 is an enlarged perspective view of select finger holder 44 which is used with the hold units 14 of the present crossbar switch 13. Select finger holder 44 is a one piece molded plastic unit, composed of acetal resin for example, which includes a plurality of mounting buttons 45, each having a groove 5! adapted to receive the bight portion 47 of select finger sets 46, and a plurality of mounting posts 48 having a generally circular cross section.

Support member 32 of the hold unit 14 has a plurality of notches 49 in the rear section of member 32, these notches being slightly greater than semicircular and designed to receive the mounting posts 48 of the select finger holder 44. In FIG. 6, a portion ofone end ofselect finger holder 44 ha been broken away to show the position of one of the notches 49, and FIG. 7 shows how the select finger holder 44 with the post 48 would join with the member 32. With this arrangement, the notches 49 being slightly greater than semicircular and the post 48 being of circular nature, the select finger holder 44 can be easily snapped into place on the rear portion of hold support member 32. This eliminates the heretofore known arrangement of individually mounting one holder for each select finger set.

As can best be seen in FIGS. 5 and 6, when the select finger sets 46 have been inserted into operative relationship with cards 39 and snapped into place around the mounting buttons 45, a portion of the generally circular bight 47 remains exposed. This portion can easily be grasped to remove a select finger 46 from the hold unit 44 should one of the select fingers 27 become broken or bent. Thus it can be seen that removal of a select finger set 46 is greatly simplified over that prior art wherein the buttons were round and and the select fingers were not easily accessible once mounted on the button.

Each of the cards 39 has in its lower portion an aperture 50 which is of the generally boomerang shape, this feature being easily seen in FIG. 6. Select finger sets 46 are inserted in the hold unit 14 by first separating the fingers 27 so that they no longer cross, and inserting the select fingers 27 through the apertures 50 of an associated pair of cards. Next the bight portion 47 of the select finger set 46 is inserted into the groove 51 of the corresponding mounting button 45, the resulting positioning of select finger set 46 being as shown in FIGS. 5 and 6. For proper operation of the crossbar switch, it is necessary that the select fingers 27 normally be positioned in the apertures 50 of the individual cards in the manner shown in FIG. 6 for those select finger sets 46 which have not been operated, i.e., in the right angle corner of aperture 50. To meet this requirement, it is necessary that the select fingers 27 be pretensioned such that each finger 27 in a particular set tends to move toward the other, and that the free end of the select fingers 27 tend to move away from the support member 32. The former requirement is accomplished by aforementioned bending the individual fingers at a point a short distance from bight 47 such that they normally cross as shown in FIG. 10. The latter requirement has heretofore been met by bending the individual select fingers at some point away from bight 47 so that after the finger sets have been mounted on the support member 32, they will normally be biased such that their free ends move away from the support member 32. As can best be seen from FIG. 9, the mounting buttons 45 on select finger holder 44 have been designed such that after the select finger set 46 has been inserted into groove 51 of button 45, an approximately 3 bias is placed on the select fingers 27, resulting in moving the free ends of the select fingers 27 away from the support member 32. This bias retains the select fingers 27 in lower portion of aperture 50. Thus it can be seen that the originally required pretensioning of the select fingers 27 is no longer necessary since the downward bias on the lower portion of the apertures 50 is now supplied by the approximately 3 angle of groove 51 in mounting buttons 45, Thus it can be seen that by using select finger holder 44 in hold unit 14, pretensioning of select fingers 27 in the second direction is no longer necessary, thus manufacturing of the select finger sets 46 is simplified greatly.

The crossbar switch 13 of the present invention operates in the same manner as the crossbar switch disclosed in US. Pat. No. 3,445,795, and therefore a detailed discussion of that operation is not necessary. The preliminary step in the operation of one of the cards 39 of the crossbar switch 13 is shown in FIG. 6. One of the select bars 52 has been rotated, as shown in FIG. 6, and operate finger 26 has positioned the associated select finger 27 in the restricted area of aperture 50. In the next step, hold magnet assembly 33 is energized which in turn rotates armature 35 toward the core of electromagnet 34 which pushes select fingers 27 toward support member 32. With the conditions as shown in FIG. 6, the only card 39 that would be moved by operation of armature 35 would be the one in which the select finger 27 had been moved into the restricted area of aperture 50. This card 39 would be moved, under the control of the select finger 27 and armature 35, upward and the movable contacts 38 associated with the card 39 would mate with the associated contacts 53 on stationary bars 37. As is conventional with this type of crossbar switch, once the hold armature 35 has been energized and the preconditioned cards 39 moved so that their controlled movable contacts 38 are mated with the stationary contacts 53, select bars 52 are allowed to return to their normal position and the selected cards 39 are retained in their new position under the control of armature 35 Although only one embodiment of the present invention has been shown, it will be readily apparent to those skilled in the art that the teachings of the invention may be practiced in slightly variant form which will fall within the scope of the invention.

What is Claimed ls:

l. A cross-coordinate switching device comprising:

a frame;

a plurality of select units mounted on said frame, each of said units including electromagnetic select means and a select bar having a plurality of operate fingers selectively operated under the control of said electromagnetic means;

a plurality of hold units mounted on said frame, each of said hold units having a support, a plurality of movable contacts, a plurality of stationary contacts, a plurality of actuating elements movably supported in said hold unit, actuating element moving means, a plurality of substantially U-shaped select finger pairs, each said pair having a mounting end at the bight of the U and a free end opposite thereof, each said select finger being operatively interposed between said moving means and a corresponding actuating element,

and said operate fingers being disposed in cooperative relationship with said select fingers for preconditioning predetermined ones of said select fingers to translate their corresponding actuating elements upon actuation of said moving means, thereby to move the respective movable contacts into or out of engagement with the associated stationary contacts;

and each said hold unit also including a unitary select finger holder having a plurality of mounting buttons each for receiving and supporting the mounting end of the select fingers of a corresponding pair, and having mounting means adapted to frictionally engage said support such that said select finger holder, as a unit, may be readily snapped into and out of place on said support.

2. The apparatus of claim 1 wherein said mounting buttons are generally semicircular in shape and said mounting end of said pairs is of generally circular shape, whereby when one of said pairs is mounted on the respective button a portion of said mounting end remains exposed.

3. The apparatus of claim 2 wherein said buttons include a groove for positioning said select fingers at an angle away from the plane of said support.

4. The apparatus of claim 1 wherein said mounting means comprises a plurality of posts of generally semicircular shape and said support includes a corresponding plurality of notches adapted to receive said posts and retain said select finger holder in place on said support.

5. The apparatus of claim 1 wherein said frame includes a channeled member for providing additional strength to said frame.

6. The apparatus of claim 1 wherein said electromagnetic select means comprises a pair of electromagnets and an armature.

7. The apparatus of claim 6 wherein the plurality of pairs of electromagnets are located on one end of said frame and said electromagnets of each said pair are positioned on opposite sides of a frame member.

4: a a it

Claims (7)

1. A cross-coordinate switching device comprising: a frame; a plurality of select units mounted on said frame, each of said units including electromagnetic select means and a select bar having a plurality of operate fingers selectively operated under the control of said electromagnetic means; a plurality of hold units mounted on said frame, each of said hold units having a support, a plurality of movable contacts, a plurality of stationary contacts, a plurality of actuating elements movably supported in said hold unit, actuating element moving means, a plurality of substantially U-shaped select finger pairs, each said pair having a mounting end at the bight of the U and a free end opposite thereof, each said select finger being operatively interposed between said moving means and a corresponding actuating element, and said operate fingers being disposed in cooperative relationship with said select fingers for preconditioning predetermined ones of said select fingers to translate their corresponding actuating elements upon actuation of said moving means, thereby to move the respective movable contacts into or out of engagement with the associated stationary contacts; and each said hold unit also including a unitary select finger holder having a plurality of mounting buttons each for receiving and supporting the mounting end of the select fingers of a corresponding pair, and having mounting means adapted to frictionally engage said support such that said select finger holder, as a unit, may be readily snapped into and out of place on said support.

2. The apparatus of claim 1 wherein said mounting buttons are generally semicircular in shape and said mounting end of said pairs is of generally circular shape, whereby when one of said pairs is mounted on the respective button a portion of said mounting end remains exposed.

3. The apparatus of claim 2 wherein said buttons include a groove for positioning said select fingers at an angle away from the plane of said support.

4. The apparatus of claim 1 wherein said mounting means comprises a plurality of posts of generally semicircular shape and said support includes a corresponding plurality of notches adapted to receive said posts and retain said select finger holder in place on said support.

5. The apparatus of claim 1 wherein said frame includes a channeled member for providing additional strength to said frame.

6. The apparatus of claim 1 wherein said electromagnetic select means comprises a pair of electromagnets and an armature.

7. The apparatus of claim 6 wherein the plurality of pairs of electromagnets are located on one end of said frame and said electromagnets of each said pair are positioned on opposite sides of a frame member.

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