US3699292A - Slidable contact member for minature switch - Google Patents

Abstract

A contact member for use in a slide type miniature switch comprises an integral sheet metal body having a base portion and a plurality of resilient contact arms. The contact arms extend from the base portion to different lengths and are bent over substantially 180* and are provided at their ends with curved contact surfaces. The contact member is adapted to be received in a recess in a slide carrier whereby the contact surfaces are pressed selectively into sliding engagement with a plurality of fixed contacts mounted on the switch housing wall. The contact arms may be dimensioned to achieve either a shorting or nonshorting switch-over operation. The contact member may be conveniently fabricated from a single piece of sheet metal and is particularly suitable for mass production techniques.

Description

United States Patent Ohkita 154] SLIDABLE CONTACT MEMBER FOR MINATURE SWITCH {72] Inventor: Masao Ohkita, Tokyo, Japan [73] Assignee: Alps Electric Co., Ltd., Tokyo,

Japan [22] Filed: June 14, I971 [21] Appl. No.: 152,577

[30] Foreign Application Priority Date July 3, 1970 Japan ..45/66533 [52] 0.8. CI ..200/l66 J, 200/16 D, 200/166 F 51 Int. Cl. ..H0lh 1/10 [58] Field of Search.200/l66 F, 166 BI-l,166 J, 16 D [56} References Cited UNITED STATES PATENTS 2,453,498 11/1948 Crowley ..200/16 D 3,392,250 7/1968 Ziegler et al. ..200/l66 J X 3,308,250 3/1967 Field et a1. ..200/166 J X 1 Oct. 17,1972

FOREIGN PATENTS OR APPLICATIONS 82,334 12/1963 France ..200/166 BH Primary Examiner-H. 0. Jones Attorney-Maxwell James et al.

[57] ABSTRACT A contact member for use in a slide type miniature switch comprises an integral sheet metal body having a base portion and a plurality of resilient contact arms. The contact arms extend from the base portion to different lengths and are bent over substantially 180 and are provided at their ends with curved contact surfaces. The contact member is adapted to be received in a recess in a slide carrier whereby the contact surfaces are pressed selectively into sliding engagement with a plurality of fixed contacts mounted on the switch housing wall. The contact arms may be dimensioned to achieve either a shorting or non-shorting switch-over operation. The contact member may be conveniently fabricated from a single piece of sheet metal and is particularly suitable for mass production techniques.

4 Claims, 10 Drawing Figures /0 l6 4 32 a 30 c 34 SLIDABLE CONTACT MEMBER FOR MINATURE SWITCH This invention relates to electric switches and more particularly to a movable contact member for use in a miniature electric switch.

Mechanically actuated electric switches are common components in a variety of electric circuit arrangements. In many applications, for example, tuning circuits in communications apparatus, size is an important factor. Thus, electric switches of the type herein described are often required for use in conjunction with miniaturized electronic circuitry. Switches of this type are provided with one or more movable contacts adapted to movably electrically engage one or more fixed contacts thereby to make or break one or more circuits.

In the past it has been found necessary, in order to insure good electrical engagement in .all the operative switch positions, to provide means to resiliently bias the movable contacts against the fixed contacts. This means usually takes the form of a separate spring biasing mechanism. In other cases the contacts themselves are resilient and are secured by soldering or the like to a movable slide member in depending relationship thereto. In either case, the contacts must be carefully positioned on the slide member and secured thereto, and appropriate electrical connections must be made. As a result, fabrication of such switching mechanisms in miniature form is time consuming and expensive. Moreover, the increasing complexity of switch mechanisms of this type significantly limits the extent to which they may be miniaturized. Finally, the use of springs and solder connections in switch mechanisms of this type significantly increases the chances of failure during operation (either mechanical or electrical) thereby shortening the expected operating life.

It is a primary object of the present invention to provide a movable switch contact having a simple inexpensive construction yet being extremely effective and reliable in operation.

It is another object of the present invention to design a movable switch contact for use in a miniaturized circuit which may be economically and effectively fabricated at reduced dimensions heretofore unattainable.

It is yet another object of the present invention to provide a slidable switch contact provided with multiple contact anns, having an improved one-piece construction adapted to significantly improve effectiveness and operating life both with regard to its mechanical and electrical operating characteristics.

To these ends the present invention comprises a miniaturized switch contact member for usein a slide type switch and adapted to make or break electrical connections between one or more fixed contacts mounted on a switch housing. The contact member comprises an elongated sheet of conductive resilient material having a base portion and provided with a plurality of contact arms longitudinally extending from said base portion. The contact arms are preferably of different lengths and are bent over near their bases to provide a generally U-shaped resilient member. The ends of the contact arms are preferably curved and project convexly outwardly from the plane of the arm itself thereby to provide a projecting contact surface. The

contact member is particularly suitable for mounting in a slidable carrier member having a recess engaging the base thereof whereby the resilient contact arms are pressed into firm sliding engagement with a wall of the switch housing. A plurality of spaced transversely extending conductive strips are mounted on the housing wall whereby the resilient contact arms selectively engage said conductive strips in response to sliding movement thereof.

In a preferred embodiment two each contact members are mounted in back to back relationship in oppos ing recesses in an elongated slide carrier adapted to slide within a channel in the switch housing. The contact membersare each compressed between the slide carrier and a wall of the switch housing channel.

The contact member ofthe present invention may be conveniently fabricated from a single small sheet of metal as by stamping or the like with any desired number of contact arms.

To the accomplishment of the above, and to such other objects as may hereinafter appear, the present invention relates to a movable contact member as defined in the appended claims and as described in this specification taken together with the accompanying drawings in which:

FIG. I is a cross sectional view of a switch mechanism utilizing the movable contact member of the present invention;

FIG. 2 is an enlarged perspective view of one embodiment of the contact member of the present invention;

FIG. 3 is a front elevational view of the contact member of FIG. 2;

FIGS. 4-6 are schematic illustrations showing three operative positions of the contact member of FIG. 2;

FIG. 7 is an enlarged perspective view of a second embodiment of the contact member of the present invention; and

FIGS. 8-10 are schematic illustrations showing three operative positions of the contact member of FIG. '7.

The movable contact member of the present inven tion is best illustrated in FIG. 2. As there shown the member generally designated 10 comprises an elongated base portion 12 and a plurality of contact arms there shown as two arms 14 and 16. Arms 14 and 16 are preferably formed integral with base portion 12 and extend from one end thereof in parallel relationship defining a slot 18 therebetween. The arms 14 and 16 extend from the base 20 of slot 18 coterminous with base portion 12 and are bent over near the base 20 of slot 18 through an angle of somewhat less than so that they extend substantially in parallel relationship with base portion 12. The sharpness of the bend as defined by the radius of curvature of the curved portions 22 and 24 of arms 14 and 16, respectively, will depend upon the characteristics of the material from which the member 10 is fabricated. Preferably, this material has good resilience to provide arms 14 and 16 with a good cantilevered spring action in operation, yet are malleable enough to be set in the generally U- shaped configuration illustrated in FIG. 2. However, as will hereinafter become apparent, the sharpness and angle of bend need not be precise as long as the ends 26 and 28 of arms 14 and 16, respectively, are spaced from base portion 12 by a predetermined spacing in accordance with the particular carrier member with which the contact member is to be used. It is these ends of the contact arms which are adapted to electrically resiliently engage the fixed contacts on the switch housmg.

For this purpose ends 26 and 28 are convexly curved outwardly away from base portion 12 to form curved contact surfaces 30 and 32, respectively. As will be explained hereinafter in more detail, these curved contact surfaces facilitate a good sliding engagement with the fixed contacts on the housing wall and insure proper spacing of arms 14 and 16 for selective engagement with the fixed contacts.

Contact member 10 may be conveniently cut from a single elongated rectangular piece of sheet metal having a width equal to the width W of base portion 12, by a stamping operation utilizing a suitable die. The curved contact surfaces may be formed simultaneously during the stamping operation or may be stamped out or machined separately thereafter. The bending of arms 14 and 16 at 22 and 24, respectively, may either be performed manually or by another stamping operation. The contact member is thus particularly suitable for fabrication by inexpensive mass production techniques.

In operation the contact member of the present invention is mounted on a slidable carrier member within a switch housing. The contact member 10 is adapted to be compressed between the carrier member and a switch housing wall mounting a plurality of fixed contacts, whereby the contact arms 14 and 16 are pressed into sliding engagement with the fixed contacts.

One such preferred arrangement of this type is illustrated in FIG. I. As there shown a carrier member generally designated 34 is slidably mounted within a channel 36 defined by two parallel switch housing walls 37. The carrier 34 is shaped like a bar bell and is provided with two oppositely facing slots or recesses 38 defined by two relatively massive portions 40 connected by a narrow beam 42. Carrier 34 is preferably integrally formed of an electrically insulating material as by molding or the like. Suitable means (not shown) such as a handle or slide finger connected to the carrier member and extending out through a slot in the switch housing (not shown) are provided for sliding the carrier 34 within channel 36 in the direction of arrow 44 in FIG. 1. Two contact members 10 are mounted on the carrier 34, one in each recess 38. The contact members I are received longitudinally in recesses 38 with their base portions l2 engaging the opposite sides of beam 42 and their contact arms facing outwardly toward opposite walls 37. Recesses 38 must be of a length sufficient to accommodate contact members with a minimum of play in order to ensure accurate positioning of the contact surfaces 30 and 32 in response to movement of the carrier member 34. The switch housing walls are provided with a plurality of conductive strips secured to the housing walls by any suitable means such as by deposition (utilizing printed circuit techniques) or by riveting, and extend transversely of the sliding direction of carrier member (arrow 44). Three such strips designated A, B, and C are shown secured to each wall 37 in FIG. I. These strips serve as fixed contacts and are electrically connected to an external device or circuit in the desired arrangement by any suitable means. It will be appreciated that as many strips as desired may be provided in accordance with the particular circuit involved and the switching action required. The spacing of strips A, B and C must be coordinated with the spacing and curvature of contact surfaces 30 and 32 of arms 14 and 16, respectively, in a manner described hereinafter in more detail. In practice, the contact members 10 are inserted in recesses 38 and the switch is assembled by inserting carrier member 34 into channel 36 in the switch housing, preferably from the left as viewed in FIG. 1. The dimensions of the contacts 10, the recesses 38 and the channel 36 are such that when the parts are thus assembled the curved contact surfaces 30 and 32 are pressed against the housing walls 37 and into firm sliding electrical engagement with conductive strips A, B, and C which serve as fixed contacts. The resiliency of contact arms 14 and 16 serves to maintain this firm sliding engagement throughout the operating life of the device.

In their compressed condition contact arms 14 and 16 are shown in FIG. 1 extending substantially parallel to base portions 12. However, this need not be the case. All that is necessary is that the contact surfaces 30 and 32 be pressed in from their normal unstressed positions (FIG. 2) sufficiently to establish firm electrical engagement with the fixed contacts A, B and C. Of course too great a compressive force of these surfaces might impede the smooth sliding movement of the contact members within channel 36. It will be appreciated, however, that there is a wide range of spacings of contact surfaces 30 and 32 from base portion 12 in the unstressed condition which will yield satisfactory operating results with a carrier and channel of given dimensions. Thus the spacing of contact surfaces 30 and 32 as shown in FIG. 2 is far from critical.

As shown in FIG. 2 contact arms 14 and 16, in their initially unstressed condition, are disposed parallel to each other. Accordingly, because of the difference in the lengths of these arms when they are compressed as shown in FIG. I there may be a slight variation in con tact pressure as between contact surface 30 and contact surface 32, particularly when they are not depressed all the way to the horizontal position there shown. Accordingly, if desired, these arms may be skewed relative to each other in the unstressed condition such that the shorter contact arm 16 extends outwardly from base portion 12 by a greater angle (or conversely arm 16 is bent through a smaller angle whereby the two contact surfaces 30 and 32 are spaced approximately equally from base portion 12). Again, however, it will be noted that this initial spacing is not critical.

In the embodiment of FIG. I the strips A, B and C are of a width substantially equal to the distance between contact surfaces 30 and 32. A switching operation is illustrated schematically in FIGS. 4-6. In the position of FIG. 4 contacts 30 and 32 are in firm electrical engagement with strips B and A respectively and accordingly the electrically conductive contact member 10 serves to electrically connect these strips B and A. As the carrier member 34 is moved to the right as viewed in FIG. 1, contact surface 32 moves from the right hand edge of strip A to the left hand edge of strip B as illustrated in FIG. 5. As there shown both contact surfaces 30 and 32 now engage a single strip B so that strips A, B and C remain electrically isolated. Thus this embodiment achieves a "non-shorting switch-over operation. Upon further movement of the carrier member 34 to the right contact surfaces 30 and 32 move to the position shown in FIG. 6 in which contact surface 32 engages strip B and contact surface 30 engages strip C. Accordingly, strips B and C are now electrically connected through the contact member 10. The spacing between strip A, B and C is such, relative to the radius of curvature of contact surfaces 30 and 32, that the terminal edges of the contact arms 14 and 16 never fall below the surface of strips A, B, and C and thus a smooth surface to surface transfer from one strip to another is insured.

It will be appreciated that the convexly curved contact surfaces 30 and 32 also serve to space the contact arms 14 and 16 from the conductive strips over which they pass but with which their respective contact surfaces 30 and 32 are not engaged. Thus in FIGS. 1 and 4 it will be seen that contact arm 14 is spaced from strip A by a distance equal to the distance contact surface 30 projects out of the plane of arm 14.

FIG. 7 shows a second embodiment of a movable contact member in accordance with the present invention having three contact arms 46, 48, and 50, having curved contact surfaces 52, 54 and 56, respectively. In this embodiment the spacing of contact surfaces 52, 54, and 56 is such that either two or all three of the conductive strips A, B, and C may be electrically connected together. Thus FIG. 8 shows the three contact surfaces 52, 54, and 56 operatively electrically connecting conductive strips A and B. Upon movement to the right these contacting surfaces are positioned to engage respectively strips A, B, and C thereby connecting all three to each other, as shown in FIG. 9. Finally, a further movement to the right results in the engagements shown in FIG. 10 in which strips B and C are electrically connected together but isolated from strip A. Accordingly, this embodiment is known as a shorting switch-over type of switch. Many other variations will be apparent. Moreover, a switch of this type is extremely versatile in that the mode of operation may be conveniently changed merely by substituting one contact member for another.

It will be appreciated from the foregoing that I have provided a movable contact member of simple construction which is particularly effective for use in a slide type miniaturized switch. The one-piece construction insures effective and reliable mechanical and electrical operating characteristics. Moreover, this member may be conveniently fabricated by inexpensive mass production techniques from a single strip of sheet metal at reduced dimensions heretofore unattainable.

While only a limited number of embodiments of the present invention have herein been specifically described, it will be appreciated that many variations may be made thereto without departing from the scope of the present invention, as defined in the appended claims.

I claim:

1. A movable contact member for use in a switch having a plurality of elongated spaced and generally parallel fixed contacts extending in a first direction, said contact member comprising an integral sheet metal body having a base portion and a plurality of resilient contact arms of different lengths extendin therefrom at one end thereof, said body being ben over more than whereby said contact arms extend across said fixed contacts generally in a second direction substantially parallel to said base portion and spaced therefrom at one side thereof and substantially transverse to said first direction, said body being adapted to be compressively engaged at its base portion with a carrier member movable in said second direction thereby to press said contact arms into resilient movable engagement with said fixed contacts, whereby said fixed contacts are selectively operatively connected to each other in accordance with the movement of said contact member.

2. The movable contact member of claim 1, wherein the ends of said contact arms comprise curved portions projecting outwardly away from said base portion, said curved portions being adapted to engage at least one of said fixed contacts and to space said contact arms from said other fixed contacts.

3. The movable contact member of claim 1, wherein the difference in the lengths of said contact arms correspond generally to the spacing of said fixed contacts.

4. The movable contact member of claim 3, wherein the ends of said contact arms comprise curved portions projecting outwardly away from said base portion, said curved portion being adapted to engage at least one of said fixed contacts and to space said contact arms from said other fixed contacts.

t i l k

Claims (4)

1. A movable contact member for use in a switch having a plurality of elongated spaced and generally parallel fixed contacts extending in a first direction, said contact member comprising an integral sheet metal body having a base portion and a plurality of resilient contact arms of different lengths extending therefrom at one end thereof, said body being bent over more than 90*whereby said contact arms extend across said fixed contacts generally in a second direction substantially parallel to said base portion and spaced therefrom at one side thereof and substantially transverse to said first direction, said body being adapted to be compressively engaged at its base portion with a carrier member movable in said second direction thereby to press said contact arms into resilient movable engagement with said fixed contacts, whereby said fixed contacts are selectively operatively connected to each other in accordance with the movement of said contact member.

2. The movable contact member of claim 1, wherein the ends of said contact arms comprise curved portions projecting outwardly away from said base portion, said curved portions being adapted to engage at least one of said fixed contacts and to space said contact arms from said other fixed contacts.

3. The movable contact member of claim 1, wherein the difference in the lengths of said contact arms correspond generally to the spacing of said fixed contacts.

4. The movable contact member of claim 3, wherein the ends of said contact arms comprise curved portions projecting outwardly away from said base portion, said curved portions being adapted to engage at least one of said fixed contacts and to space said contact arms from said other fixed contacts.

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