US3680025A - Contactless push button switch - Google Patents

Abstract

A contactless push button switch comprising a magnetic circuit including a magnet, stationary yokes, a movable yoke and a fieldsensitive element (such as reluctance effect element, hole effect element, SMD, etc.), said magnetic circuit being disposed between a button cover and a base of the switch. By depressing the button cover the movable yoke is caused to undergo a physical change, thereby extremely reducing the density of the magnetic flux penetrating the field-sensitive element to cause a change of the terminal voltage or electro-motive force across the fieldsensitive element so as to bring about the switching action of the switch.

Description

FIF85112 XR 516818 1025 A United States Patent [151 3,680,025

Kobayashi 1 1 July 25, 1972 [s41 CONTACTLESS PUSH BUTTON OTHER PUBLICATIONS SWITCH IBM Technical Disclosure Bulletin, Vol 6, No. 11, April,

[72] Inventor: Tsunekazu Kobayashi, Kawasaki, Japan 1964 Funk et al., variable Mode Pushbutton Switch Assignee: onkyo p y Unified Tokyo, Primary Examiner-D. F. Duggan Japan Arramey-Chittick, Pfund, Birch, Samuels & Gauthier [22] Filed: Sept. 18, 1970 [21] Appl.No.: 73,391

[57] ABSTRACT A contactless push button switch comprising a magnetic circuit including a magnet, stationary yokes, a movable yoke and Foreign Allllncamm Priority Data :1 field-sensitive element (such as reluctance effect element, Sept. 19, 1970 Japan ..45/88864 hole effect element 1 Said magnetic cimuil being Sept 9, 1970 Japan 45 13 3 5 disposed between a button cover and a base of the switch. By

depressing the button cover the movable yoke is caused to un- [52] U.S. C1 ..338/32, 335/1, 310/10 de go a physical change. thereby extremely reducing the den- [51] Int. Cl ..I-l01c 7/16 sity of the, magnetic flux penetrating the field-sensitive ele- [58] Field of Search ..310/DlG. 10, 15; 335/1, 2; ment to cause achange of the terminal voltage or electro-mo- 338/32 R, 32 H tive force across the field-sensitive element so as to bring about the switching action of the switch. [56] References Cited UNITED STATES PATENTS 8 CM 8 Dr I n ms, aw n res 3,537,046 10/1970 l-lubrich et al ..338/32 R x g PAIENTEDJum-s m2 SHEEI 1 (IF 2 FIG. 3

F IG.

FIG. 2

I NVENTOR TSUNEKAZUA Ko'BAYAsm BY l 1-? CONTACTLESS PUSH BUTTON SWITCH BACKGROUND OF THE INVENTION This invention relates to contactless push button switches and, more particularly, to contactless push button switches utilizing the effects of a change of magnetic field intensity on a field-sensitive element such as relactance efiect element, hole element, SMD, etc.

Heretofore, table electronic computors, push button telephone sets and various other apparatus have used lead switches having mechanical contacts such as spring contacts.

These mechanical contact switches require relatively large I space for installation on the, installation panel. Also, they are likely to give rise to misfunctioning of the system using them due to chattering caused when their contacts are made and broken.

Meanwhile, owing to the recent advance in the IC technique various miniatuarized electronic circuits are readily produced, giving rise to the demand for small-size and highly reliable switches.

SUMMARY OF THE INVENTION The principal object of the invention, accordingly, is to pro vide a contactless switch, which uses a field-sensitive element and a magnet to utilize the phenomenon that the electromotive force or terminal voltage across the field-sensitive element changes with change in the intensity of magnetic field thereacross, and which can provide an excellent switching characteristic suitable for use in combination with transistors and other active circuit elements.

Another object of the invention is to provide a contactless push button switch using a field-sensitive element, which is of a construction requiring a relatively small extent of displacement of the switch button to produce the switching action though the top area of the button is slightly large.

A further object of the invention is to provide a contactless push button switch using a field-sensitive element, in which the top area of the switch button is reduced.

A still further object of the invention is to provide a contactless push button switch using a field-sensitive element, which is free from a spring providing a restoring force against the depression of the switch button.

A yet further object of the invention is to provide a contactless push button switch using a field-sensitive element, which has two or more magnets to permit the selection of the intensity of themagnetic field across the field-sensitive element.

The contactless push button switch according to the invention comprises a magnetic circuit disposed between a switch button-cover and a switch base and including one or more magnets, stationary yokes, a movable yoke and a field-sensitive element (such as reluctance effect element, hole element, SMD, etc.), these components being arranged in such a manner that by depressing the switch button-cover at least part of the movable yoke is rotated about the top of a stationary yoke, thereby extremely reducing the density of the mag netic flux across the field-sensitive element to cause a change of the terminal voltage or electro-motive force across the field-sensitive element so as to bring about the switching action of the switch. Thus, the service life of the switch according to the invention can be extended almost infinitely owing to the freedom from the switch contacts unlike the conventional lead switches. Also, extreme reliability is ensured owing to the freedom from the chattering of the switch contacts. Further, the reduction of the switch size may be readily attained, as it is possible to accommodate all the essential component parts within the switch button-cover.

These and other objects, features and advantages of the invention will become more apparent from the description of the illustrated preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a plan view showing an embodiment of the contactless push button switch according to the invention. FIG. 2 is a section taken along line IIII' in FIG. 1.

FIG. 3 is a section taken along line III-III in FIG. I.

FIG. 4 is a plan view showing another embodiment of the contactless push button switch according to the invention.

FIG. Sis a section taken along line V-V' in FIG. 4.

FIG. 6 is a section taken along line VI-VI' in FIG. 4.

FIG. 7 is a sectional view showing a further embodiment of the invention.

FIG. 8 is a sectional view showing a still further embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS. 1 to 3, a preferredembodiment of the contactless push button switch according to the invention is shown having a casing comprising a switch button-cover I having a substantially square top surface and a switch base 2 having a base area smaller than the area of the bottomopening of the switch button-cover l. The switch button-cover l is provided with two parallel legs 4 extending from the inside 3 of its top wall. The legs 4 extend through respective openings 5 formed in the switch base 4. Wound oneach leg 4 is a spring 6 disposed between the inside face of the top wall of the switch button-cover l and the top face of the switch base 2, sothat when the switch button-cover I is depressed the springs 6 urge it to its original position relative to the switch base 2 as shown in FIG 2. Each leg 4 is provided on the side of the switch base 2 opposite the spring 6 with a cotter pin 21 serving as a stopper to determine the inoperative position of the switch button-cover I. The cotter pin 21 also serves to prevent the vibration of the switch button-cover 1 when the button-cover is depressed and ensure reliable downward displace-ment of the switch button-cover. The switch base 2 is secured to a panel 20 by means of a central bolt 17 and a nut 18. The bolt 17 is embedded in the switch base 2. An elongate magnet 7 lies on top of the switch base 2. It is in contact with and longitudinally held between fixed yokes 8 and 9. As is seen from FIGS. 2 and 3, the fixed yoke 8 extends upright from the switch base 2 beyond the magnet 7,.and it is provided on the inner side of its portion extending beyond the magnet 7 with a field-sensitive element I0, which is in contact with both the yoke 8 and the magnet 7. The leads of the field-sensitive element 10 are taken out at lead terminals 19. The other fixed yoke 9, whose height is less than that of the fixed yoke ,8, has its top in contact with a movable yoke II. The movable yoke 11 has a straight portion terminating .in front of the field-sensitive element 10 as indicated at 12 and the remaining portion extending toward the bottom opening of the switch buttoncover I and terminating in the vicinity of the corner wall 14 thereof as indicated at 13. The corner of the switch buttoncover 1 corresponding to the end 13 of the movable yoke 11 has a thick wall portion 15 terminating in an inclined shoulder 16 terminating in the portion 14.

By the term field-sensitive element" appearing throughout the specification is meant the well-known element such as reluctance effect element and hole element which has certain properties undergoing a change-in the presence of a magnetic field. It is used as an element to provide switching function by utilizing the change of the electric resistance ad as a control element to generate a control voltage controlling a switching element (such as a transistor and thyristor).

The fixed yokes 8 and 9 and the movable yoke 11 are made of a magnetic material. Thus, when the switch button-cover I is held in its inoperative position shown in FIG. 2 by the urging force of the springs 6, the end of the movable yoke 11 supported on top of the fixed yoke 9 is attracted to the magnet 7. In this state, the yokes 8, 9 and 11 and the magnet 7 form a closed magnetic loop, so that the field-sensitive element 10 in front of the end 12 of the movable yoke 11 is placed in the magnetic field present in the magnetic circuit. Thus, the fieldsensitive element 10 offers a high resistance if it is a reluctance effect element. If it is a hole element, a hole voltage appears at the hole terminal.

In the operation of the embodiment described above, when the switch button-cover I is not depressed but is held in itsinoperative position with respect to the switch base 2 by the urging force of the springs 6 as shown in FIGS. 2 and 3, the fieldsensitive element 10 offers a high resistance or provides a high bole voltage. In this state, when the switch button-cover I is depressed against the spring force of the spring 6, the inclined shoulder 16 of the switch button-cover 1 pushes down the end 13 of the movable yoke 11 to cause the rotation of the movable yoke 11 about the top of the fixed yoke 9 in the clockwise direction in FIG. 2. As a result, the end 12 of the movable yoke 11 is displaced away from both the field-sensitive element I and the fixed yoke 8. This means that the field-sensitive element is displaced out of the magnetic circuit. In other words, the intensity of the magnetic field across the field-sensitive element 10 is reduced to a negligible value. Thus, if the field-sensitive element 10 is a reluctance effect element its resistance is reduced, and if it is a hole element its hole voltage is extremely reduced. With this change a switching signal may of course be produced. When the pressure on the depressed switch button-cover 1 is released, the switch button-cover is forced back to its original inoperative position as shown in FIGS. 2 and 3 by the restoring force of the spring 6.

In the embodiment described above, the switch buttoncover 1 is provided with two legs 4 extending from the inside face 3 of its top wall and penetrating through the switch base 2. These legs are employed to stabilize the frictional movement of the switch button-cover 1 toward the switch base 2. The two legs are thus by no means limitative, but any suitable number of legs may be employed. Also, the shoulder construction constituted by the inclined shoulder 16 between the wall portions 14 and 15 of the switch button-cover 1 is not limitative, and any alternative means may be used so long as such means is brought into emgagement with and pushes down the end 13 of the movable yoke 11; for example, a projection may replace the inclined shoulder 16.

As is described, in the preceding embodiment the substantial portion of the movable yoke extends along the longitudinal direction of the elongate magnet supported on the switch base, so that the straight portion of the movable yoke from its pivotal point to its end in front of the field-sensitive element, that is, the portion of the movable yoke constituting the magnetic path, may be made sufficiently long. In other words, the preceding embodiment has the advantage that a relatively small extent of displacement of the switch button-cover is required to break the magnetic circuit of the movable yoke though the area of the top of the switch, that is, thetop of the switch button-cover, is slightly large. Thus, the contactless push button switch in the preceding embodiment may be effectively used for apparatus, in which the area of the switch installation is sufficiently available but the distance of the displacement of the'switch button-cover toward the switch base is not sufficiently available.

FIGS. 4 to 6 show another embodiment of the contactless push button switch according to the invention. The illustrated switch has a casing comprising a switch button-cover 31 having a substantially square top surface. and a switch base 32. The switch base 32 is secured to a panel 49 by means of a threaded projection 47 extending from the switch base 32 and a nut 48 fitted on the threaded projection 47. The switch button-cover 31 is provided with a leg 34 extending from the inside face 33 of its top wall. The switch button-cover l is also formed with a guide bore 35. The switch base 32 is formed with an opening 36, through which the leg 34 extends, and provided with an upright upper projection 37 extending into the bore 35. On the leg 34 is mounted a spring 38 disposed between the top wall 33 of the switch button-cover 31 and the switch base 32, so that when the switch button-cover 31 is depressed the spring 38 urges it toward its original position relative to the switch base 32 as shown in FIG. 5. The leg 34 is provided on the side of the switch base 32 opposite the spring 38 with a cotter pin 50 serving as a stopper to determine the inoperative position of the switch button-cover 31. The cotter pin 50 also serves to prevent the vibration of the switch button-cover 31 when the button-cover is depressed and ensure reliable action of the switch. In this embodiment, an elongate rectangular magnet 39 lies on a first fixed yoke 40 supported on the switch base 32. On top of the magnet 39 lies a second fixed yoke 41. The second fixed yoke 41 is formed at one end thereof with a projection 42 pivotally supporting a movable yoke 43. The movable yoke 43 has a straight portion terminating in front of a field-sensitive element 45 placed on the first fixed yoke 40, as indicated at 44. It is bent at its point in contact with the top of the projection 42, and its upper portion then upwardly inclined and terminates in an end portion 46 substantially parallel to the inside face 33 of the top wall of the switch button-cover 31. The first and second fixed yokes 40 and 41 and the movable yoke 43 are made of a magnetic material. Thus, when the switch button-cover 31 is held in its inoperative position shown in FIG. 5 by the urging force of the spring 38, the lower end 44 of the movable yoke 43 supported on the projection 42 of the second fixed yoke 41 is attracted to the magnet 39. In this state, the yokes 40, 41 and 43 and the magnet 39 form a closed magnetic loop, so that the field-sensitive element 45 in front of the lower end 44 of the movable yoke 43 is placed in the magnetic field present in the magnetic circuit. Thus, similar to the previous embodiment, if the fieldsensitive element 45 is a reactance effect element, it offers a high resistance, while if it is a hole element, a hole voltage appears at the hole terminal.

In the operation of this embodiment, when the switch button-cover 31 is not depressed, it is held in its inoperative position with respect to the switch base 32 by the urging force of the spring 38 as shown in FIGS. 5 and 6. In this state, similar to the previous embodiment, the field-sensitive element 45 offers a high resistance or provides a high hole voltage. When the switch button-cover 31 in this state is depressed against the spring force of the spring 38, the inside face 33 of its top wall pushes down the upper end portion 46 of the movable yoke 43 to cause the rotation of the movable yoke 41 about the top of the projection 42 of the second fixed yoke 41 in the counterclockwise direction. As a result, the lower end 44 of the movable yoke 43 is revolved in the counterclockwise direction away from the field-sensitive element 45 and the first fixed yoke 40. This means that the field-sensitive element 45 is displaced out of the magnetic circuit. In other words, the intensity of the magnetic field across the field-sensitive element 45 is reduced to a negligible value. Thus, if the field-sensitive element 45 is a reluctance effect element its resistance is reduced, and if it is a hole element its hole voltage is extremely reduced. With this change a switching signal may of course be produced. When the pressure on the depressed switch buttoncover 31 is released, the switch button-cover if forced back to its original inoperative position as shown in FIGS. 2 and 3 by the restoring force of the spring 38.

In this embodiment, the substantial portion of the movable yoke extends along the longitudinal direction of the elongate magnet erected on the switch base, so that the area of the top surface of the switch button-cover may be reduced as compared to the previous embodiment. Thus, the contactless push button switch in the preceding embodiment may be effectively used when installing many switches in a panel of a constant area.

FIG. 7 shown a further embodiment of the invention. Its casing comprises a switch button-cover 51 having a substantially square top surface and a switch base 52 having a base area smaller than the area of the bottom opening of the switch button-cover 51. The switch base 51 is secured to a panel 60 by means of a central bolt 58 and a nut 59. An elongate magnet 53 lies on top of the switch base 52. It is in contact with and longitudinally held between fixed yokes 54 and 55. The fixed yoke 54 extends upright from the switch base 52 beyond the magnet 53, and it is provided on the inner side of its portion extending beyond the magnet 53 with a field-sensitive element 57, which is in contact with both the yoke 54 and magnet 53. The other fixed yoke 55, whose height is less than that of the fixed yoke 54, has top in contact with a movable yoke 56.

The movable yoke 56 has a straight portion terminating in front of the field-sensitive element 57 as indicated at 56. The remaining portion of the movable yoke 56 extends downwardly from the pivotally supported spot, is folded back upwardly and terminates in an upper end portion 56" substantially parallel to and in contact with the inside face of the top wall of the switch button-cover 51.

The operation of this embodiment is essentially the same as the operation of the preceding embodiments shown in FIGS. 1 to 4 and in FIGS. 4 to 6, so the detailed description of the operation will not be given here.

In this embodiment, the coil spring or springs as in the preceding embodiments of FIGS. 1 to 3 and of FIGS. 4 to 6 is dispensed with, thus reducing the number of component parts.

FIG. 8 shows a modification of the embodiment of FIG. 7. In the Figure, the same parts or similar parts having the same function as those shown in FIG. 7 are designated by identical reference numerals. This embodiment differs from the embodiment of FIG. 7 in that in this embodiment another magnet 53' is bonded to the fixed yoke 54 on the side opposite the magnet 53. With this construction by appropriately selecting the size, configuration and material of the second magnet 53', the intensity of the magnetic field in the magnetic circuit may be selectively varied to, in turn, vary the amount of pressure which must be applied to depress the switch button-cover 51.

What is claimed is:

l. A contactless push button switch comprising a boxshaped switch button-cover having an open bottom and at least one leg extending downwardly-from the inside of the top wall of said switch button-cover, a switch base located below and adapted to fit within said switch button-cover, said switch base being formed with at least one opening, each of said legs of said switch button-cover being guided through one of said openings, a spring mounted on each of said legs, each of said springs providing restoring force against the displacement of said switch button-cover toward said switch base, an elongated magnet lying on top of said switch base and within said switch button-cover, said magnet extending horizontally and being provided at opposite ends with fixed yokes, the second one of which extends above said magnets, a field-sensitive element fixed on the inner side of a portion of the second one of said fixed yokes, said field-sensitive element being in contact with both said second fixed yoke and said magnet, and a movable yoke pivotally supported on top of the first one of said fixed yokes, said movable yoke having a portion on the side of the pivotal support point nearer to said field-sensitive element which constitutes a magnetic circuit together with said field-sensitive element, said switch button-cover having an inwardly projected portion adaptedto push down the portion of said movable yoke extending on the other side of said pivotal support point to pivot said movable yoke and break said magnetic circuit when said switch button-cover is depressed against the forces of said springs.

2. The contactless push button switch according to claim I, wherein each of said legs is provided on the side of said switch base opposite said switch button-cover with a projection serving as a stopper and said projections also serve to prevent the vibration of said switch button-cover when said switch buttoncover is depressed and ensure reliable downward displacement of said switch button-cover.

3. The contactless push button switch according to claim 2 wherein each of said projections is a cotter pin.

4. A contactless push button switch comprising a switch button-cover having a leg extending from the inside face of the top wall of said switch button-cover, said switch button-cover being formed with a guide bore, a switch base formed with an opening and provided with an upright projection, said leg of said switch button-cover being guided through said opening and said upright projection extending into said bore of said switch button-cover, a spring mounted on said leg of said switch button-cover, said spring providing restoring force against the displacement of said switch button-cover toward said switch base, an elongated magnet erected over the top of said switch base, said magnet being provided at opposite ends with fixed yokes, a field-sensitive element in contact with both the upper face of the first one of said fixed yokes and a side face of said magnet, and a movable yoke pivotally supported on top of a projection of the second one of said fixed yokes, said movable yoke havinga portion on the side of the pivotal support point nearer to said field-sensitive element which constitutes a magnetic circuit together with'said field-sensitive element, and wherein depression of said switch button-cover against the force of said spring causes the inside face of the top wall of said switch button-cover to push down the end of a portion of said movable yoke extending on the other side of said pivotal support point to break said magnetic circuit, and wherein said leg is provided on the side of said switch base opposite said switch button-cover with a projection serving as a stopper and said projection also serves to prevent the vibration of said switch button-cover when said switch buttoncover is depressed and to ensure reliable downward displacement of said switch button-cover. I

5. The contactless push button switch accordingly to claim 4, wherein said projection is a cotter pin.

6. A contactless push button switch comprising a switch button-cover, a switch base, an elongated magnet lying on top of said switch base, said magnet being provided at opposite ends with .fixed yokes, the second one of which extends beyond the top face of said magnet, a field-sensitive element in contact with both the inner side of a portion of the second one of said fixed yokes extending beyond said magnet and the top face of said magnet, and a movable yoke pivotally supported on top of the first one of said fixed yokes, said movable yoke having a portion on the side of said pivotal support point nearer to said field-sensitive element which constitutes a magnetic circuit together with said field-sensitive element and a portion on the other side of said pivotal supportpoint which extends downwardly from said pivotal support point, is then folded back upwardly and terminates in an end portion in contact with the top wall of said switch button-cover, whereby depression of said switch button-cover causes rotation of said movable yoke to break said magnetic circuit, and further comprising a second magnet whose magnetic field interacts with said magnetic circuit so that the intensity of the magnetic field in said magnetic circuit is adjustably selecting the size and material of said second magnet.

7. A contactless push button switch comprising a boxshaped switch button-cover having an open bottom and a leg extending downwardly from the inside face of the top wall of said switch button-cover, said switch button-cover being formed with a downwardly extending guide bore, a switch base formed with an opening and provided with an upright projection, said leg of said switch button-cover being guided through said opening and said upright projection extending into said bore of said switch button-cover, a spring mounted on said leg of said switch button-cover, said spring providing restoring force against the displacement of said switch buttoncover toward said switch base, anelongated magnet located within said switch button-cover and erected over the top of said switch base, said magnet being provided at opposite ends with fixed yokes, a field-sensitive element in contact with both the upper face of the first one of said fixed yokes and a side face of said magnet, and a movable yoke pivotally supported on top of a projection of the second one of said fixed yokes, said movable yoke having a portion on the side of the pivotal support point nearer to said field-sensitive element which constitutes a magnetic circuit together with said field-sensitive element, and wherein depression of said switch button-cover against the force of said spring causes the inside face of the top wall of said switch button-cover to push down the end of a portion of said movable yoke extending on the other side of said pivotal support point to break said magnetic circuit.

8. A contactless push button switch comprising a boxshaped switch button-cover having an open bottom, a switch base located below and adapted to fit within said switch button-cover, an elongated magnet lying within said switch butsaid field-sensitive element and a portion on the other side of said pivotal support point which extends downwardly from said pivotal support point. is folded back upwardly and ter minates in an end portion in contact with the top wall of said switch button-cover, whereby depression of said switch button-cover causes the rotation of said movable yoke to break' said magnetic circuit.

*0 l l l l

Claims (8)

1. A contactless push button switch comprising a box-shaped switch button-cover having an open bottom and at least one leg extending downwardly from the inside of the top wall of saiD switch button-cover, a switch base located below and adapted to fit within said switch button-cover, said switch base being formed with at least one opening, each of said legs of said switch button-cover being guided through one of said openings, a spring mounted on each of said legs, each of said springs providing restoring force against the displacement of said switch button-cover toward said switch base, an elongated magnet lying on top of said switch base and within said switch button-cover, said magnet extending horizontally and being provided at opposite ends with fixed yokes, the second one of which extends above said magnets, a field-sensitive element fixed on the inner side of a portion of the second one of said fixed yokes, said fieldsensitive element being in contact with both said second fixed yoke and said magnet, and a movable yoke pivotally supported on top of the first one of said fixed yokes, said movable yoke having a portion on the side of the pivotal support point nearer to said field-sensitive element which constitutes a magnetic circuit together with said field-sensitive element, said switch button-cover having an inwardly projected portion adapted to push down the portion of said movable yoke extending on the other side of said pivotal support point to pivot said movable yoke and break said magnetic circuit when said switch button-cover is depressed against the forces of said springs.

2. The contactless push button switch according to claim 1, wherein each of said legs is provided on the side of said switch base opposite said switch button-cover with a projection serving as a stopper and said projections also serve to prevent the vibration of said switch button-cover when said switch button-cover is depressed and ensure reliable downward displacement of said switch button-cover.

3. The contactless push button switch according to claim 2 wherein each of said projections is a cotter pin.

4. A contactless push button switch comprising a switch button-cover having a leg extending from the inside face of the top wall of said switch button-cover, said switch button-cover being formed with a guide bore, a switch base formed with an opening and provided with an upright projection, said leg of said switch button-cover being guided through said opening and said upright projection extending into said bore of said switch button-cover, a spring mounted on said leg of said switch button-cover, said spring providing restoring force against the displacement of said switch button-cover toward said switch base, an elongated magnet erected over the top of said switch base, said magnet being provided at opposite ends with fixed yokes, a field-sensitive element in contact with both the upper face of the first one of said fixed yokes and a side face of said magnet, and a movable yoke pivotally supported on top of a projection of the second one of said fixed yokes, said movable yoke having a portion on the side of the pivotal support point nearer to said field-sensitive element which constitutes a magnetic circuit together with said field-sensitive element, and wherein depression of said switch button-cover against the force of said spring causes the inside face of the top wall of said switch button-cover to push down the end of a portion of said movable yoke extending on the other side of said pivotal support point to break said magnetic circuit, and wherein said leg is provided on the side of said switch base opposite said switch button-cover with a projection serving as a stopper and said projection also serves to prevent the vibration of said switch button-cover when said switch button-cover is depressed and to ensure reliable downward displacement of said switch button-cover.

5. The contactless push button switch accordingly to claim 4, wherein said projection is a cotter pin.

6. A contactless push button switch comprising a switch button-cover, a switch base, an elongated magnet lying on top of said switch base, said magnet being provided at opposite Ends with fixed yokes, the second one of which extends beyond the top face of said magnet, a field-sensitive element in contact with both the inner side of a portion of the second one of said fixed yokes extending beyond said magnet and the top face of said magnet, and a movable yoke pivotally supported on top of the first one of said fixed yokes, said movable yoke having a portion on the side of said pivotal support point nearer to said field-sensitive element which constitutes a magnetic circuit together with said field-sensitive element and a portion on the other side of said pivotal support point which extends downwardly from said pivotal support point, is then folded back upwardly and terminates in an end portion in contact with the top wall of said switch button-cover, whereby depression of said switch button-cover causes rotation of said movable yoke to break said magnetic circuit, and further comprising a second magnet whose magnetic field interacts with said magnetic circuit so that the intensity of the magnetic field in said magnetic circuit is adjustably selecting the size and material of said second magnet.

7. A contactless push button switch comprising a box-shaped switch button-cover having an open bottom and a leg extending downwardly from the inside face of the top wall of said switch button-cover, said switch button-cover being formed with a downwardly extending guide bore, a switch base formed with an opening and provided with an upright projection, said leg of said switch button-cover being guided through said opening and said upright projection extending into said bore of said switch button-cover, a spring mounted on said leg of said switch button-cover, said spring providing restoring force against the displacement of said switch button-cover toward said switch base, an elongated magnet located within said switch button-cover and erected over the top of said switch base, said magnet being provided at opposite ends with fixed yokes, a field-sensitive element in contact with both the upper face of the first one of said fixed yokes and a side face of said magnet, and a movable yoke pivotally supported on top of a projection of the second one of said fixed yokes, said movable yoke having a portion on the side of the pivotal support point nearer to said field-sensitive element which constitutes a magnetic circuit together with said field-sensitive element, and wherein depression of said switch button-cover against the force of said spring causes the inside face of the top wall of said switch button-cover to push down the end of a portion of said movable yoke extending on the other side of said pivotal support point to break said magnetic circuit.

8. A contactless push button switch comprising a box-shaped switch button-cover having an open bottom, a switch base located below and adapted to fit within said switch button-cover, an elongated magnet lying within said switch button-cover and on top of said switch base, said magnet being provided at opposite ends with fixed yokes, the second one of which extends above said magnet, a field-sensitive element in contact with both the inner side of a portion of the second one of said fixed yokes and the top face of said magnet, and a movable yoke pivotally supported on top of the first one of said fixed yokes, said movable yoke having a portion on the side of said pivotal support point nearer to said field-sensitive element which constitutes a magnetic circuit together with said field-sensitive element and a portion on the other side of said pivotal support point which extends downwardly from said pivotal support point, is folded back upwardly and terminates in an end portion in contact with the top wall of said switch button-cover, whereby depression of said switch button-cover causes the rotation of said movable yoke to break said magnetic circuit.

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