Improved Detent Means For Slide Switch And Printed Circuit Structure

Abstract

A slide switch of low profile particularly adapted for use with printed circuits. The terminals of the switch are stationary conductor pattern elements of the printed circuit and the movable contact parts are carried by a slider of insulating material. The slider is mounted in a circuit board slot which serves as a track for axial slider action. A caliper type mechanism (resilient detent arm) engages detent slots in the circuit board or provides the coupling means for ganging multiple switch stages to each other.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application if filed with claim of priority pursuant to 35 U.S.C. 119, the same invention having been filed by applicant in the Federal Republic of Germany as application No. P 1920784.2, on Apr. 24, 1969.

BACKGROUND OF THE INVENTION

1. Field of The Invention

The present invention relates to switches and more particularly to slider type switches adapted for use on printed circuit boards in electronic equipment.

2. Description of The Prior Art

In general, there have been a number of approaches to the problem of constructing a slide switch to be mounted into a printed circuit, in which the stationary contact parts are components of, or held by said printed circuit and the movable contact parts are carried by a slider of insulating material. Such slide switches are particularly useful in the construction of broadcast receivers, tape recorders and dictating machines. In such devices of current manufacture, printed circuits are widely used. A specific example is the wave switch of a broadcast received. In known slide switches, the stationary contact parts are formed as elements of the conducting pattern of the printed circuit. That particular prior art is typically shown in German Petty Pat. No. 1 745 285.

In other known slide switches, the stationary contact parts are installed in the printed circuit board, in the form of round pins which are pressed or driven into the printed circuit for example, this art being described in German Pat. No. 1 121 163. In other known switch structures, resilient contact bridges serve as movable contacts, the bridges being guided along the printed circuit board. An important disadvantage of these known switches is that they occupy relatively large spaces. Accordingly, their use is difficult where minimum space is available.

A flat design requiring little space is obtained if contact springs attached to the printed circuit board and connected with the conducting pattern serve as movable contact parts. In that switch form, the contact springs are actuated by a slider of insulating material which is guided in a recess of the printed circuit board as described in German Petty Pat. No. 1,840,481. That configuration suffers the disadvantage that, in order to obtain the movable contact parts, groups of contact springs must be mounted, (riveted for example) on the printed circuit board and conductively connected with the printed circuit. In addition, electrical disadvantages result from the fact that the slider, when inserted between the movable contact parts, is subject to heavy wear and, as a result, the contacts become smeared. Furthermore, this known slide switch is not suitable for multiple (ganged) switching functions such as they occur in program controlling systems.

In order to obtain a switch which is capable of performing a plurality of switching functions, several independent, individual slide switches have heretofore been assembled into a multiple (gang) switch by suitably placing one behind the other, as in German Pat. No. 1,245,475. However, that art does not lend itself to construction of slide switches or multiple switches intended for use in printed circuit equipment.

SUMMARY OF THE INVENTION

In consideration of the disadvantages of the prior art, it may be said to be the general object of the invention to provide a modular slide switch of particularly low profile design, which can be mounted on a printed circuit board as an independent part or included in a multiple switch. In the present invention, the said slider is slideably inserted in the guide slot of said printed circuit board and, at one of its ends, provided with at least one resilient detent arm which slides along said board when the switch is actuated, and engages with one of a plurality of detent recesses (slots) in said board for each intended switching position. Since the slider of insulating material is displaceably arranged and is inserted through the plane of the insulating plate or circuit board, the slide switch according to the invention is of particularly small height (profile). Smearing of the contacts during the insertion of the slider into the recess of the plate cannot occur because the movable contact parts are carried by the slider.

For the slide switch according to the invention, the engaging (positioning) problem is solved in an especially simple manner which is characterized in that a detent arm capable of engaging with recesses in said insulating plate (circuit board) is provided at said slider. In a preferred embodiment of the invention, this detent arm is designed in the form of a caliper consisting of two symmetrical parts of equal length, which are molded to said slider. This caliper slides above and below, applying a nominal "biting" pressure to said board. The jaws of this caliper jointly engage the recess in said board corresponding to a discrete position. In principle, a one-piece detent arm would be sufficient to afford a secure detent, however, with a one-piece detent arm, a certain degree of canting and, consequently, jamming of the sliding contact can occur. However, the locking pressures of the two parts of the "caliper" (two-piece) detent arm, (normal to the plane of the circuit board) on the slider are cancelled if the two caliper parts are exactly arranged in a mirror-inverted arrangement, i.e., symmetrically. This also results in a degree of mechanical stress relief for the printed circuit board, the latter normally not being designed to resist wear producing pressures to any great extent.

The problem of guiding the slider along the plate of insulating material circuit board is, for the slide switch according to the present invention, solved in an especially simple manner by providing for guidance of said slider along the edges of said guide slot. To this end, according to a further feature of the invention, at least two resilient tongues lying on opposite slot sides from each other can be molded to said slider. These tongues engage said slot with barblike noses and, during a switching movement, slide along the edges of said slot. Such a snap attachment of the slider permits an especially simple assemblage of the slide switch on the printed circuit board.

In order to prevent the slider from being actuated beyond the intended lock positions during switching movements, an advantageous feature of the invention is characterized in that at the slider two pairs of such spring tongues lying opposite each other are provided. In the direction of actuation they can simultaneously form the two end stops for the limitation of the switching movement in both directions.

In order to insure the adaptability of the invention for the performance of a great variety of switching functions, the slide switch is, according to a further feature of the invention, designed so that it can be used both individually and ganged. To this end, the slider is (at its end opposite the detent arms) provided with a recess into which the detent arms of a second slider placed behind it (having the same shape) can be engaged for the formation of a mechanical connection between both sliders. Thus the same detent arm design not only fulfills the required detention function but also will act as a connecting element between two sliders. In particular, a plurality of sliders, arranged one behind the other, can be interconnected in this manner. To this end, each slider has such a recess, and therein a head portion having an undercut neck where it joins the resilient detent arms, so that, when placing the individual sliders one behind the other, the detent arm of the following slider engages the head member and detents over the said neck and thus provides a connection for transmitting the switching movement directly to the next slider. Thus it is possible to compose a multiple (gang) switch on the building-block principle using independent individual slide switches which can be made in a simple, standardized manner. Accordingly, the manufacturing cost of such a multiple switch is low, particularly because the hitherto required, often quite complicated and costly special designs are no longer necessary.

Further features and advantages of the invention will be apparent from the following description of the basic single unit and ganged embodiments shown in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bottom view of a slide switch according to the invention.

FIG. 2 is a sideview of the slide switch of Figure 1 mounted on a printed circuit board.

FIG. 3 is a sectional view of a multiple switch mounted on a printed circuit board and consisting of two slide switches of the type shown in FIGS. 1 and 2, arranged one behind the other.

FIG. 4 is a sectional view taken on parting line 4-4 of Figure 5.

FIG. 5 is a partial flat view of a circuit board useable in the structure of the invention.

FIG. 6 is a section taken along the parting line 6-6 of the slide switch shown in Figure 1 after this switch has been mounted on a printed circuit board.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the description to follow, the structure pointed out will be found variously in the drawings, not necessarily in order of Figure numbers.

The reference character 1 designates the printed circuit board on which the stationary contact parts 2, 2', 2" of the slide switch are provided as components of the printed circuit. Contact springs 3, which are identical in sliders 4 and 5, slide on the stationary contact parts 2, 2', 2", serving as movable contacts when the switch is actuated. These contact parts are appropriately designed as two-armed double springs and undetachably mounted on the sliders 4 and 5. Electrical continuity between the spring pairs on each side of the slot 6 is provided within the slider body 4 (or 5) so that they are capable of connecting the stationary contacts 2 with 2' in one switching position of the slider 4. Similarly, the contact parts 2 with 2" are interconnected in the other position, thereby effecting a swtich-over or single-pole double-throw switching logic.

Since the detailed parts associated with 5 are identical with those of 4, the description and illustration of such details in connection with 4, will be understood to also apply to 5.

In order to insure a space-saving design, the slider 4 is axially slideably seated in a slot 6 of the insulating plate 1. The slider 4 is guided along opposite edges of the slot 6 and portions of the slider protrude through the plate. Spring tongues 7 and 7' molded to the slider 4 hold the slideable engagement and prevent separation of 4 from slot 6. It will be seen that four such spring tongues with their barblike noses are used, and are arranged by twos transversely with respect to the direction of actuation, see FIG. 6 and FIG. 1 where the barblike noses 8 through 8'" are shown.

The said barblike nose 8 and 8', respectively, which engage the edges of slot 6, slide along an edge of said slot during a switching movement. The slider 4 is mounted on the insulating plate 1 simply by being pressed into the slot 6. After the pressing-in operation, the resilient tongues 7, 7' of the slider 4 spread out and prevent the slider from falling out of the printed circuit board 1 by the under-grip the said barbs provide. The resilient tongues 7, 7' simultaneously act as an end stop for the limitation of the switching movement in one direction. The other end stop is formed by the connecting element 12 of the detent arm portion 9' against 10'.

For the realization of definite switching positions, the sliders 4 and 5 are provided with molded resilient detent arms 9 and 10, respectively, which slide along the board 1 when the switch is actuated to engage recesses 11, 11' of the board 1 in the corresponding switching positions. With regard to the load on the sliders 4 and 5 and the printed circuit board 1, it is appropriate to design the detent arms 9 and 10 in two pieces, e.g., in the shape of a caliper. In this design, both parts 9' and 9" and 10' and 10", respectively, of the detent arms 9 and 10 can, when the switch is actuated, slide along above and below the board 1 and jointly engage by means of a "biting" action with the recesses 11 and 11' of the board in the switching positions. For obtaining stable switching positions while also reducing the sliding friction during actuation, the two portions 9' and 9" plus 10' and 10", respectively, of the detent arms 9 and 10 each have, at their free ends, a semicircular engaging nose 9"' and 9"" plus 10"' and 10"", respectively. These engaging noses are adapted to the detenting recesses 11 and 11' of the circuit board 1.

In addition to the detenting function provided by these resilient members 9' and 9", an alternative function for these parts is available. Consider the FIG. 3 view, in this ganged embodiment the slider 5 is tandem connected to 4. To effect this connection, the engaging noses 10"' and 10"" of the slider 5 are engaged with an appropriately designed recess 4' in the slider 4. This recess may be thought of as a neck, or undercut, in the partly tapered head-shaped member 13 (also 13' on 5). Thus, the multiple switch shown in FIG. 3 is obtained, comprising two individual slide switches 4 and 5 arranged one behind the other. The cross sectioning lines are spaced differently for better identification of parts associated with each of the 4 and 5 sliders. Since the slider 5 also has an identical recess 5' suitable for the engagement of a detent arm, it is possible to interconnect additional sliders arranged one behind the other, the detent arm of each engaging the recess of the preceding slider in the same manner.

Eyelets 4" and 5", respectively, are molded to the sliders and provide connections for actuating each individually or to actuate the assembled sliders 4 and 5 as a unit. It will be noted that the detent arms of a switch module ganged to another module are spread laterally more than when they engage detent slots in the circuit board (see FIG. 3). Accordingly, the engagement retention forces between 4 and 5 are significantly greater than the detent force against the circuit board. In connection with a printed circuit, a slide switch or multiple switch according to the invention can perform a great variety of switching functions. Production and assembly costs are extremely low. For example, the insulating plate carrying the conducting pattern need only be provided with stationary contact parts 2, 2', 2", a slot 6 for the reception of the slider four-fifths, and engaging recesses 11 and 11' for the engagement of the detent arm nine-tenths, while on the side of the insulating plate opposite the stationary contact parts, other printed connections for the various circuit components may be arranged. By suitably designing the printed circuit board, it is thus possible to carry out a multitude of switching operations without the requirement for wiring in a separate switch assembly during equipment manufacture. Moreover, special means for mounting the slider on the printed circuit board and for ganging sliders are no longer necessary when the present invention is used. Once the integral assembly steps are complete, the slide switch or the multiple switch composed of individual slide switches is ready for operation. Extraneous shifting is prevented by stops formed of the mounting tongues 7, 7' and connecting elements 12, 12', respectively, as has been apparent from FIGS. 3 and 6.

Various modifications and variations within the spirit of the invention are possible. It is not intended that the scope of the invention should be limited by the drawings or description, the latter being only illustrative and typical.

Claims

What we claim is:

1. A slide switch in which the stationary contacts are parts of the printed conductors of a printed circuit board and the movable contact parts are carried by a slide member of insulating material comprising the combination of:

means defining a mounting slot through the thickness of said circuit board, said slot being elongated in the direction of actuation of said slide switch;

slide mounting means for holding said slide in place with substantially only translational freedom in the direction of said actuation and with said movable contact parts in position to contact said stationary contacts, at least some parts associated with said slide protruding from the side of the board opposite said stationary contacts;

a plurality of detent slots substantially along the actuation centerline of said mounting slot and spaced relationship at one end of said mounting slot;

and detent means including at least one resilient detent arm having a nose engageable in one of said detent slots and being attached to said slide, said detent arm extending toward said detent slots and being adapted to exert lateral contact pressure on said board thereby to facilitate engagement of said nose into one of said detent slots in response to actuation of said switch to effect a corresponding switch position.

2. Apparatus according to claim 1 in which said detent means is defined as a substantially identical caliperlike pair of said resilient arms extending from said slide toward said detent slots on opposite surfaces of said circuit board, whereby the corresponding noses of said resilient arms engage the same one of said detent slots from opposite sides of said circuit board to position said switch to a corresponding switch position.

3. The invention set forth in claim 2 in which said slide includes a head member having an undercut extending oppositely from the direction of extension of said resilient arms, whereby the resilient arms of a second one of said slides may be ganged thereto by sliding the resilient arms of said second slide over said head member until the noses of said resilient arms engage said undercut.

4. Apparatus according to claim 3 in which the lateral dimension of said head member and the depth of said undercut are such that said resilient arms mated thereto are spread laterally against their resiliency more than said resilient arms are spread when functioning as a detent mechanism, whereby the separation force is greater than the force required to actuate said switch from a detented position.

5. A slide switch in which the stationary contacts are parts of the printed conductors of a printed circuit board and the movable contact parts are carried by a slide member of insulating material, comprising the combination of:

means defining a mounting slot through the thickness of said circuit board, said slot being elongated in the direction of actuation of said slide switch;

and resilient means extending from said slide member through said slot, said resilient means being located and shaped to resiliently grip the edges of said mounting slot thereby to maintain contact pressure of said movable contact parts against the surface of said circuit board and said stationary contacts, and also to restrict said slide member from substantial movement except in the said direction of actuation.

6. Apparatus according to claim 5 in which said resilient means extending through said slot comprise a plurality of resilient tongues extending substantially normal to said circuit board through said mounting slot, and means are included at the extreme end of each of said tongues for engaging the edges of said mounting slot to provide said contact pressure of said movable contact parts against the surface of said circuit board.

7. Apparatus according to claim 6 in which said tongues are four in number, two on each side of said slide in spaced relationship, and said means for engaging the edges of said mounting slot consists of a barblike nose at said extreme end of each of said tongues.