US3400347A

US3400347A - Magnetic reed switch

Info

Publication number: US3400347A
Application number: US545766A
Authority: US
Inventors: Macys Albert; Marinace Richard
Original assignee: Sperry Rand Corp
Current assignee: Sperry Corp
Priority date: 1966-04-27
Filing date: 1966-04-27
Publication date: 1968-09-03
Anticipated expiration: 1985-09-03
Also published as: DE1665924B2; GB1184612A; DE1665924A1

Description

Sept. 3, 1968 A. MACYS ET AL 3,400,347

MAGNETIC REED SWITCH Filed April 27. 1966 I 2 Sheets-Sheet 1 32 22 66 62 20 3 INVENTOR 48 72 ALBERT MACYS RICHARD MARINACE av 52b J United States Patent 3,400,347 MAGNETIC REED SWITCH Albert Macys, Plymouth Meeting, and Richard Marinace, Erdenheim, Pa., assignors to Sperry Rand Corporation, New York, N.Y., a corporation of Delaware Filed Apr. 27, 1966, Ser. No. 545,766 11 Claims. (Cl. 335-151) ABSTRACT OF THE DISCLOSURE This invention comprises an ON-OFF switch which utilizes a reed member in conjunction with a permanent magnet. In particular the switch comprises a pressure plate pivotally mounted on a base channel and held there by a spring and spring retainer means. The base channel is held in position in an opening by means of outwardly and oppositely facing notches in order to receive the top edges of the switch assembly. By means of the above techniques, the entire assembly can be fabricated with a minimum of parts and the elimination of attachment devices to interconnect the various parts. Manual pressure on the pressure plate moves the permanent magnetic inoperative relation to the magnetic reed member. In operation, the reed switch is opened by pointing one pole of the permanent magnet at the overlapping portion of flexible reed switch members thus providing a snap action or repulse opening. During closing, the pole of the permanent magnet is pointed away from the overlapping portion of the flexible members. The switch closes with constant acceleration and the contacts close with a snap action since the overlapping reed member ends have induced in them fields of opposite polarity. This causes an attractive force to exist between the ends of the reed member which because of their flexibility allows them to come together into intimate contact.

This invention relates to switch actuators and assemblies, but more particularly to switch actuators and assemblies of the magnetic reed switch type.

Its objective is the provision of such switch actuators and assemblies which are characterized by their simple and inexpensive design enabling actuation of magnetic reed switches in either an alternate ON/ OFF, or a momentary mode. Its economy is characterized by its adaptibility to automated manufacturing and assembly techniques wherein costly manual operations are minimized.

Briefly described, the invention comprises a control element or pressure plate pivotally mounted on a base channel and held there by spring means which also pror vides the operative force cooperating with manual pressure on the pressure plate for moving permanent magnets in operative relation to magnetic reed switches, preferably mounted On a printed circuit board. Resilient elements of the base channel enable it to be snapped into and held in supporting structure.

In the drawings:

FIG. 1 is a perspective view of a fragmentary portion of a control panel having mounted thereon a group of switches constructed in accordance with the preferred embodiment of the present invention;

FIG. 2 is a sectional view taken along the line 22 of FIG. 1 and showing a switch assembled for the momentary mode of actuation;

FIG. 3 is a sectional view taken along the line 33 of FIG. 2 with parts broken away;

FIG. 4 is a sectional View of a single switch assembly enabling the alternate ON/OFF mode of actuation, and shown in its on condition;

FIG. 5 is a view similar to FIG. 4 but showing the switch in its alternate o condition;

FIG. 6 is a fragmentary view showing details of the Patented Sept. 3, 1968 spring arm used in the alternate mode switch assembly;

FIG. 7 is a perspective view of a switch base channel for accommodating four switches in a unitary assembly; and

FIG. 8 is a bottom view of the switch actuator or pressure plate.

Referring now to the details of the drawings and first to FIG. 1, it is seen that the numeral 10 identifies a control panel upon which four switch assemblies 12 are mounted, although this is an arbitrary number which could range from only one switch to any desired number. The switches, as brought out more clearly hereinafter, may all be of one mode of operation, momentary or alternate ON/OFF, or a mixture of 'both. An important feature of the invention is that the selection of operating modes is easily and rapidly eflected by merely using a modified part during assembly, as will be understood as the description continues.

First describing a single switch of the momentary actuation type, and as seen in FIGS. 2 and 3, the numeral 14 designates the base or channel of the switch actuator as sembly. The base comprises a pair of spaced

side walls

16 and 18 having inwardly projecting

bottom flanges

20 and 22, respectively, interconnected at their bottom edges by spaced end or bridge members 24, as more clearly shown in FIG. 7. Preferably the base channel is molded of a plastic material, such as nylon, with sufficient flexibility to enable the

walls

16 and 18 to be sprung inwardly by the pressure of tapering portions 26 against the edges of the panel opening 28 as the channel is forced downwardly into the opening during assembly. When the top edge flanges 30 contact the top surface of panel 10 the walls spring outwardly to engage the edges of the panel opening in the notches formed in the walls between the tapering portions 26 and the flanges 30, thus releasibly to lock the channel in place on the panel. To impart additional rigidity at the bottom of the channel, downturned edges 32 may be provided on

flanges

20 and 22.

Each of the bridges 24 has a centrally positioned upwardly extending hill-like projection 34 terminating below the top edges of base channel 14. A bearing seat or slot 36 is provided in the top of the hill 34 pivotally to receive finger bearings 38 depending from opposite side walls 39 of a hollow butterfly shaped pressure plate 40. With reference to FIG. 8, it is seen that the pressure plate is rectangularly shaped in plan and open on its under side. Depending from its underside is a centrally positioned wall 42 extending from one end wall 44 to the other, and dividing the hollow underside into opposite cavities 46. Spaced along the bottom edge of wall 42 are three small apertures 47a, b and 0, one in the center and one adjacent each of its oposite ends, the purposes of which will be explained later. Depending from each cavity is a pair of tubes 48, the tubes of each pair being spaced from each other on opposite sides of an imaginary line drawn between the bearing fingers 38.

Each tube is split to form two separated flexible finger members 50 running substantially throughout its length for receiving and holding a cylindrical magnet 52 (FIG. 2). Usually only one magnet is provided for each pair of tubes, or alternatively, as explained below, Only one to a switch. As seen in FIG. 2 only the left hand tube on the near side, and the right hand tube on the far side of wall 42 are provided with magnets, identified by the numerals 52a and 521), respectively. Each magnet is arranged for movement between terminal position and relative to one of a pair of

magnetic read switches

54a and 54b mounted beneath the magnets, preferably on a printed circuit board '56 supported beneath the control panel 10 as by screws 58 threaded into elongated bosses 60 depending from the underside of the panel (only one being shown).

It is understood, as indicated above, that each switch assembly could be provided with only one reed switch, if desired. With two, however, there is provided a momentary single pole double throw switch wherein reed switch 541] is maintained in a normally open condition by magnet 52b, and reed switch 54a is normally closed. Pressing down on the raised left hand side of pressure plate 40 reverses the positions of the magnets and the conditions of their respective reed switches.

The reed switches are of well known construction wherein contact elements 61 a, b, c and a (not shown) extend axially through an elongated glass housing from opposite ends, with their inner ends in closely spaced overlapping relation whereby exposure of one of said contacts to magnetic flux attracts the other to it, thus to close the contacts until the magnetic force is removed.

In particular and by way of example, when magnet 52a is in the position shown in FIGURE 2, a magnetic pole is induced in the single contact element 61a of reed switch 54a which is opposite to the magnetic polarity at the end of the permanent magnet. In other words, assuming the end of the magnet 52a is a north pole, then a south pole is induced at the terminal portion of element 6111. Therefore, the contact element 61a at the overlapping gap position has a north pole induced therein. In like manner, the contact element 61b of the reed switch 54a furtherest from the magnet 52a has a south pole induced at the end near the overlapping gap position and north pole is induced at the terminal point. Summarizing the above, the overlapping but not touch ing reed member ends have induced into them by means of the permanent magnet poles of opposite polarity which causes an attractive force to exist between the overlapping reed member ends, which because of their flexibility, allows them to come together in intimate contact. It should be noted that by proper positioning, the permanent magnet field has no influence on reed switch 54b The opening of the contact elements 61a and b of the reed switch 54a occurs in the following manner. The pressure plate 40 is operated so that the magnet 52a points directly at the gap of the overlapping contact elements 61a and b. Accordingly, the same magnetic poles but opposite from the magnetic polarity of the end of the permanent magnet are induced at the overlapping and touching reed member ends 61a and b. In other words, assuming the end of the magnet 52a is a north pole, then a south pole is induced in each of the overlapping end points of the contacts 61a and b whereas the terminal points of contacts 61a and b have north poles induced therein. Since the contacts at the gap have the same magnetic polarity, they repel each other and therefore open very rapidly moving past their normally open position. Summarizing the above, the inducing of the same polarity at the overlapping ends of the contact elements 61a and b by the permanent magnet causes a repelling force to exist between them. Since the magnetic repulsion and the built-in spring restoring force are both acting in the same direction, the speed of contact opening is greatly accelerated. The magnetic repulsion continues to act and keeps the contacts moving past the normally open position to one further apart until eventually, the spring restoring forces balance the magnetic repulsion force. The above-described operation provides a snap action type of operation which could not be achieved otherwise.

The snap-action type of operation of the instant invention provides numerous advantages: the higher speed break action reduces the contact transistion time and therefore, the internal switch dissipation. The contact life or current handling capabilities are thus increased; the greater contact opening speed and ultimately wider contact gap provide for a greater are quenching characteristic; are ionization also tend to be impeded by the perpendicular lines of force existing in the gap at the neutral point between the similarly polarized reed members; the

ultimately wider :gap allows a greater break-down voltage rating to be applied; the magnetic repulsive force holding the gap open increase the shock and vibration resistance and provide for a damping action; the wider contact gap reduces the inter-element capacity. These and other advantages will become apparent to those skilled in the art.

In the present case the on-otf switch action is provided by the V-shaped arm spring retainer 62, the left hand arm of which has a transverse bar 64 at its upper end spanning a pair of bridges 24 and seated in notches or slots 66 in the under surfaces thereof, see FIG. 7. The upper end of the other arm 68 of the arm spring retainer abuts fixed structure, such as the under surface of channel flange 22, while the bottom ends of both arms are interconnected by ashort transverse loop (see FIG. 3). A coil spring 72 has one end attached to the loop and its other end to the wall 42 of pressure plate 40 through aperture 470. With this arrangement it is seen that the spring pressure is always exerted downwardly on the right hand side of the pressure plate. Therefore, as soon as the pressure is released after depressing the raised left hand portion of the pressure plate to actuate the switch, the coil spring will return the switch to its normal position illustrated in FIG. 2.

A particular feature of the invention is that it enables rapid assembly of the switch actuator without screws or other attachment devices. The force of coil spring 72 between the arm spring retainer 62 and aperture 470 of wall 42 of the pressure plate releasably locks all of the elements in their operative positions.

Another feature of the invention resides in the reversability of the spring arrangement. In other words, the upper end of arm 68 of V-shaped arm spring retainer 62 could be arranged to abut flange 20 merely by turning it around during assembly and connecting the upper end of coil spring 72 to the left hand aperture 47a in wall 42 of the pressure plate. In this case, the normal position of the parts would elevate the right hand side of the pressure plate instead of the left, and reverse the conditions of the reed switches by placing magnet 52a in position to hold reed switch 54a in a normally open condition, and moving magnet 52b away from reed switch 54b causing it to close.

While the printed circuit board 56 has been shown dependently mounted from the control panel 10 on bosses 60, it will be understood that the panel can as well comprise a portion of a unitary switch structure wherein the reed switches are preassembled with the actuator, as described below in more detail.

With reference now to FIGS. 4, 5 and 6 it will be seen and understood how a switch actuator assembly can 'be assembled with an alternate ON/OFF mode of actuation.

Instead of the V-shaped arm spring retainer 62 of FIG. 2, a U-shaped arm spring retainer (FIG. 6) is used. Its vertical arms are provided with out-turned ends 82 which are seated in the slots 66 in opposing bridges 24. The coil spring 72 is connected between the crossbar 84 of spring arm 80 and central aperture 47b in wall 42 of the pressure plate 40. As seen in FIG. 4, the right hand side of plate 40 is depressed and the force of coil spring 72 is overcenter to the left relative to the pivotal mounting of arm spring ends 82. In this condition the bar 84 is biased against fingers 50 of left hand tubes 48, and the right hand bottom edge 86 of pressure plate 40 is biased against the top surfaces of a pair of bridge members 24, thus to establish one terminal position of the actuator assembly relative to the reed switch 88. In this assembly, only one reed switch and one magnet 52 is utilized for clarity. It is to be understood, however, that others may be used, as desired to fit the need. Reed switch 88 is now in its ON condition since contacts 88a and 8811 have opposite magnetic poles induced therein at the overlapping gap positions, as magnet 52 has been moved to its retracted terminal position.

To move the switch to its OFF condition, the raised left hand side of the plate is depressed until its lower edge 90 rests on bridges 24, 'as seen in FIG. 5, thus to move the force of coil spring arm 72 overcenter on the opposite side of spring ends 82, which releasably locks the v assembly in its other terminal position with magnet 52 operatively associated with the reed switch 88. In this position, the same magnetic poles are induced in the

contacts

88a and 88b due to the position of the permanent magnet 52 in the manner 'as described above.

Still with reference to FIG. 4, it is seen that each switch may be assembled as a unitary structure enclosed by walls 92 and having the reed switches mounted on a bottom wall 94. This wall may .be 'a separate piece, such as the printed circuit board shown, secured in place by suitable well known means, not shown, or it may comprise the bottom wall of the box.

As shown in FIG. 1, the switches may easily be assembled in multiples of all one mode of operation, or as a mixture of momentary and alternate modes-merely by the use of different spring retainers in the individual switches, as described above. The assembly may comprise a group of individual switches, but preferably they would be assembled as a unit on the elongated base channel 14, as seen in FIG. 7. In this construction, the intermediate bridges 2411 are double faced, i.e., each has oppositely facing finger bearing slots 36 and spring slots 66 separated by thin walls 102 and 104', respectively. The end bridges of course have only one of each slot, facing inwardly. All four of the switch actuators could have their associated reed switches mounted on a single printed circuit board, if desired. Alternatively, each could have its own board.

In the above description it will be understood that the pressure plate with its walls and tubes, preferably is molded 'as a unitary piece and of a plastic material, such as nylon. With this unitary construction and the elimination of attachment devices to interconnect the various parts, it is seen that this assembly accomplishes its purposes with a minimum of parts and lends itself toinexpensive automated manufacturing techniques. With the use of printed circuit boards even hand wiring and soldering have been eliminated.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as (follows:

1. A switch actuator for magnetic reed switches comprising:

(A) a base structure formed by spaced side members and spaced bridging end members extending between and interconnecting said side members;

(B) said end members being provided with hearing notches in their upper and lower surfaces;

(C) an actuator pressure plate extending across said base between said side members and having bearing portions seated in said upper bearing notches in a manner permitting limited pivotal movement of said plate;

(D) an arm member having end portions seated in said lower notches of said end members, and other portions depending beneath said end members;

(E) spring means having one end connected to the underside of said plate and its other end connected to the depending portion of said arm member thereby releasably retaining said plate on said end members for its limited pivotal movement from at least one stable state;

(F) a permanent magnet having a lengthwise dimension wherein one end along said lengthwise dimension is polarized with one polarity and the other end is polarized with a second polarity; and

(G) means for securing said magnet to the underside of said plate for movement by said plate between terminal positions beneath said plate and relative to a magnetic reed switch having overlapping flexible members positioned at one of said terminal positions, said magnet being positioned relative to said reed switch so that one polarized end points at the gap formed by the overlapping ends of said flexible member when said reed switch is in the open position and said polarized end of said magnet points away from said gap when said reed switch is in the closed position.

2. A switch actuator construction according to claim 1 and further including:

(A) means on the underside of said plate for selectively connecting said one end of the spring to said plate on either side of, or aligned with said bearing portions.

3. A switch actuator in accordance with claim 1 wherein:

(A) another end portion of said arm member abuts fixed base structure to one side of the bearing notches; and

(B) said one end of said spring means is connected to the underside of said plate at a point between the ends of said arm member whereby said plate is always biased by said spring means toward one stable state.

4. A switch actuator construction according to claim 1 wherein:

(A) said one end of said spring means is connected to the underside of said plate in line with said bearing portions, whereby the spring face is movable overcenter relative to a line drawn between said upper and lower bearing notches thus to urge said pressure plate to either of its terminal portions depending upon which side of the said line the spring connection is on.

5. A switch actuator in accordance with claim 2 where- (A) said means for connecting the spring to the underside of said plate comprises awall depending from the underside of said plate and extending between and normal to said bearing portions; and

(B) said magnet mounting means comprises pairs of elongated resilient arcuately shaped members defining split tubes depending from said plate on opposite sides of said wall.

'6. A switch actuator according to claim 1, wherein:

(A) said side members are side walls;

(B) said end members bridge the space between the side Walls and interconnect the bottoms thereof; and

.. (C) each of said bridge members is provided with a centrally located raised hill portion, in the top of which is located the upper bearing notches, whereby said plate is positioned across the tops of said side walls and the pivotal movement of said plate is limited by contact of its opposite end edges with the bridge members at points adjacent to where they join said side walls.

7. A switch actuator construction according to claim 6 wherein:

(A) said base structure is elongated and provided with a plurality of said spaced bridging end members, forming pairs; and wherein .(B) each pair of said bridging end members supports a pressure plate in its upper bearing notches each held thereon by its own arm member and spring means.

8. A switch comprising:

(B) said end members being provided with bearing notches in their upper and lower surfaces;

(F) a permanent magnet having a lengthwise dimension wherein one end along said lengthwise dimension is polarized with one polarity and the other end is polarized with a second polarity;

(G) means for securing said magnet to the underside of said plate for movement by said plate between terminal positions beneath said plate;

(H) a magnetic reed switch having flexible members wherein the end portions of said members are overlapping; and

(I) means mounting said reed switch beneath said magnet adjacent one of its terminal positions to be actuated by said magnet when the magnet is in said one terminal position,

said magnet being positioned relative to said reed switch so that one polarized end points at the gap formed by the overlapping ends of said flexible members when said reed switch is in the open position and said polarized end of said magnet points away from said gap when said reed switch is in the closed position.

9. -A switch according to claim 8 wherein:

(A) said reed switch mounting means comprises a boxlike structure with inwardly facing edge flanges along opposite top edges, and

(B) said side members of said base structure are side Walls having outwardly and oppositely facing notches along their top edges to receive said top edge flanges of said box-like structure and support said base structure depending Within said box-like structure; (C) said reed switches being mounted on the bottom wall of said box-like structure.

10. A switch construction according to claim 8 where- (A) said base structure is elongated and provided with a plurality of said spaced bridging end members forming pairs; and wherein (B) each pair of said bridging end members supports a pressure plate in its upper bearing notches, each held thereon by its own arm member and spring means.

11. The switch combination comprising,

(A) a reed switch comprising overlapping contact elements;

(B) a permanent magnet member positioned in close References Cited UNITED STATES PATENTS 2,831,934 4/ 1958 Moran.

FOREIGN PATENTS 948,497 I/ 1949 France.

OTHER REFERENCES IBM Tech. Disel. Bulletin; Berkman, Toggle Switch,

April 1962, consisting of one page, p. 19.

ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistant Examiner.