Laminated Magnetic Switch

This invention relates to magnetically actuated thin reed switches.

Reed switches are well known in the art. My colleague John. D. Dick suggested to me, before my conception of my inventions claimed herein, that a thin reed switch might be constructed using a pair of layer bits of magnetically responsive material laminated to spaced flexible plastic sheets, whereby moving a magnet external to the switch relatively to it would cause the bits to move together to actuate the switch.

I have discovered that an improved switch assembly may be provided by using a magnetizable reed movable between two positions, in one of which it is in contact with two magnetizable pole pieces.

In preferred embodiments the pole pieces are defined by common planes, the reed is provided with contact portions of reduced area, the reed is provided with taut mounting at its end closer to a pole piece, the reed is adhesively secured to a supporting layer, and certain layers are relieved to cooperatively provide space connections.

I turn now to description of the drawings and the structure and operation of a preferred embodiment.

FIG. 1 is a vertical sectional view, taken at 1--1 of FIG. 3, of a switch according to the invention.

FIG. 2 is a vertical sectional view, taken at 2--2, of a portion of said switch;

FIG. 3 is a plan view of said portion of said switch; and

FIGS. 4A through 4I are plan views of elements of the FIG. 1 combination.

There is shown in FIG. 1 a switch assembly indicated generally at 10. Switch assembly 10 includes top portion 12, core portion 14, and bottom portion 16.

Top portion 12 consists of top sheet 18 of 0.005 inch thick polycarbonate having a decorated finish. Layer 18 is secured by adhesive 20 to top spacer 22, of 0.032 inch thick polycarbonate. Top spacer 22 is adhered by layer 24 of adhesive to pole piece 26, pole filler 28, and pole piece 30. Pole pieces 26 and 30 are formed from 0.006 inch layers of magnetic material (a fifty percent nickel, fifty percent iron alloy sold by Magnetic Metals Co. under the trademark HIGH PERM 49), fully annealed and bearing on each side a 0.0003 inch thickness of nickel plate. Secured to the lower surfaces of elements 26, 28 and 30 by a layer of adhesive 32 is pole spacer 34, which is formed of 0.010 inch thick polyester and adhered through adhesive 36 to suspension element 38, formed of 0.003 inch thick polyester. Secured beneath element 38 through adhesive 40 is reed spacer 42, formed of 0.005 inch thick polyester. Secured therebeneath by adhesive 44 is cover sheet 46, formed of 0.003 inch thick polyester. Secured therebeneath through adhesive 48 is base spacer 50, formed of 0.032 inch thick polycarbonate. Secured therebeneath through adhesive 52 is base sheet 54, of 0.003 inch thick polyester. Adhered therebeneath, and shown somewhat diagramatically (the upper adhesive layer attaching it to element 54 is not separately shown, nor is the release sheet at the absolute bottom) is double stick tape element 56.

Plan views of each of the non-adhesive elements referred to are set forth in FIGS. 4I (top sheet 18), 4H (top spacer 22), 4B (pole piece 26), 4A (pole filler 28), 4C (pole piece 30), 4F (pole spacer 34), 4E (suspension element 38), 4F (reed spacer 42), 4G (cover sheet 46), 4H (base spacer 50), 4I (base sheet 54), and 4I (double stick tape element 56).

FIG. 2 is a section through the core portion, indicated generally in this view, at 14. In this view, in which the section is taken centrally of the switch assembly rather than as in FIG. 1, there is shown a reed 58 secured by adhesive layer 60 on suspension band portion 62 of suspension element 38; the area 64 over which the adhesive extends is indicated by the dashed lines in FIG. 4E. (Both FIG. 1 and FIG. 2 are drawn to different scales in a width direction and in a thickness direction; the extent of the difference is virtually manifest in FIG. 2 in the apparent change of thickness in the uprising portion of reed 58; in actuality the spacer is the same thickness throughout.) Reed 58 is downwardly offset in its lowermost portion 70. Reed 58 is positioned in zone 72 defined by open portions in pole spacer 34, suspension element 38, and reed spacer 42. Reed 58, which is shown in plan view in FIG. 4D, is formed of the 0.006 inch thick material, HIGH PERM 49, of transformer grade and fully annealed, to which we have already referred.

Turning to the plan views of various elements there is shown in FIG. 4A the notch 74 in pole filler 28. In FIG. 4B is shown slot 76 in pole piece 26. In FIG. 4C is shown slot 78 in pole piece 30. In FIG. 4E are shown slots 80, 82 and rectangular opening 84 in suspension element 38. In FIG. 4F are shown slots 86, 88 and rectangular opening 90 in pole spacer 34 and reed spacer 42, which are both shown in plan view in this figure. In FIG. 4G are shown slots 92, 94 in cover sheet 46. In FIG. 4H are shown cut out portions 96, 98 in the bottom left-hand and right-hand corners, respectively, of top spacer 22 and base spacer 50, which are both shown in plan view of this figure.

In manufacture, the core assembly 14, which results in a fully operable switch, is completed and other sheets are added thereafter.

The laminated character of the device permits use of sheet construction techniques enabling assembly simultaneously of a number of switches, with separation then as a later production step.

Movement of a magnet (not shown, and which need not be permanent) toward the central portion of the thin magnetic switch 10 creates a magnetic path which first closes the gap between upper dimple 68 and pole piece 30 (unless the two were already in contact). Reed 58 then rocks about dimple 68 twisting suspension band 62 to bring edge 100 into contact with pole piece 26 to complete a circuit which is maintained closed so long as the magnet remains in close enough proximity; when this is no longer true, untwisting of suspension band 62 causes reed 58 to return to the position shown in FIG. 2.

The generally C-shaped (in cross-section) openings defined by relieved portion 96, 98; 76, 78; 86, 88; 80, 84; and 92, 94 provide for contact with the switch assembly through spade connections to be made with two female spade connectors, which can be introduced by movement in the direction to the paper in FIG. 1.

Provision of the dimple 68 not only facilitates pivoting of reed 58, but it as well centralizes mechanical force on reed 58, provides for more focused and better electrical contact, and aids in optimizing magnetic flux line patterns. Positioning dimple 68 centrally of suspension band 62, directly above the axis of rotation of suspension band 62, prevents transfer through the reed of forces on the dimple 68 when it engages portion 30. Provision of line contact 100 also facilitates electrical contact and magnetic flux conditions.

The slot 66 in suspension element 38 permits greatly increased flexibility of the suspension portion 62 and even when pole piece 30 actually contacts dimple 68 helps to prevent undesirable transfer of mechanical forces from that end portion of the reed to the other end portion thereof.