Galvano-magnetro Effect Apparatus

Abstract

A galvano-magnetro effect apparatus in which a magnetic upper yoke and a flexible and magnetic lower yoke are arranged in parallel, a magnetic rotating shaft is mounted on said upper yoke so that an end of the shaft is positioned close to the lower yoke, at least one magnet is provided between said upper yoke and lower yoke so that a magnetic flux flows in the rotating shaft, a projected end which eccentrically moves in reference to the axis of the rotating shaft is provided at the lower surface of said rotating shaft, a magnetro-effect resistance device whose resistance between terminals is varied by eccentric movement of said projected end is arranged at said lower yoke, and a pushing means which pushes up the lower yoke and pushes upward the device securing position of the lower yoke is provided below the lower yoke.

Description

BACKGROUND OF THE INVENTION

The present invention relates to the galvano-magnetro effect apparatus employing the magnetro-resistance effect device.

Conventional apparatuses of this type such as, for example, a potentio-meter have been confronted with difficulty in obtaining a uniform output characteristic of a product because the gap formed between the rotating shaft and the device slightly varies due to a mechanical error in workmanship on component parts, the intensity of magnetic field applied to the device differs with error in magnetization of a magnet which supplies the magnetic flux to the rotating shaft and the characteristics of the device are irregular.

The present invention provides the galvano-magnetro effect apparatus which can eliminate the disadvantages described above.

SUMMARY

The present invention is comprised of a base plate provided with a through hole, a magentic upper yoke attached under said base plate, a flexible and magnetic lower yoke oppositely arranged parallel with said upper yoke, at least one magnet positioned between said upper yoke and lower yoke, a rotating shaft whose lower end inserted into the through hole of said base plate is positioned close to said lower yoke and main part is forced to contact said upper yoke, a magnetro-resistance effect device fixed above said lower yoke so that the device is opposed to the lower end of said rotating shaft and a pushing means which pushes up the device mounting position of said lower yoke from the underside, wherein said rotating shaft has the lower part, below the position where the shaft contacts said upper yoke, which is made of a magnetic material so that a lower part forms a closed magnetic path by being combined with said upper yoke, lower yoke and magnet and a projected end which is provided at the lower end of the shaft and moves eccentrically in reference to the axis of the rotating shaft along with rotation of said rotating shaft, said magnet is arranged having one pole end contacting the upper yoke and the other pole end contacting the lower yoke so that the magnetic flux can be concentrated to the gap formed between the projected end of said rotating shaft and the device, said device is provided with at least two terminals and the magnetism sensing surface between the terminals formed so that its opposing area to the projected end varies with eccentric movement of the projected end along with rotation of the rotating shaft, and said pushing means is designed so that the pushing force applied to the lower yoke can be varied in order to push up the device mounting position of said lower yoke toward the projected end of rotating shaft.

BRIEF DESCRIPTION OF DRAWINGS

The present invention is illustrated in detail by the accompanying drawings whereon:

FIG. 1 is a plan view of the apparatus according to the present invention,

FIG. 2 is a cross sectional view as seen along line II--II in FIG. 1,

FIG. 3 is a cross sectional view as seen along line III-- III in FIG. 1,

FIG. 4 is a bottom view as seen along line IV--IV in FIG. 2,

FIG. 5 is a plan view as seen along line V--V in FIG. 2,

FIGS. 6 and 7 are respectively cross sectional views illustrating another embodiment of the apparatus,

FIG. 8 is a plan view illustrating another embodiment of the lower yoke to be employed in the apparatus,

FIGS. 9 and 10 are respectively cross sectional views illustrating another embodiment of the pushing means to be employed in the apparatus,

FIG. 11 is a bottom view illustrating another embodiment of the pushing means, and

FIGS. 12 to 14 are respectively plan views illustrating the embodiment of the magnetro-resistance effect device to be employed in the apparatus.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 to 5, there is shown an galvano-magnetro effect apparatus comprising base plate 10 provided with through hole 11 at its center, upper yoke 20 fixed to said base plate so that the upper yoke surrounds said through hole, pressing means 40 such as, for example, the support base which is opposed in parallel with said upper yoke and is connected to the upper yoke with coupling lever 30, at least one magnet 50 which is interpositioned between said upper yoke and support base, lower yoke 60 provided between said magnet 50 and support base 40, a magnetro-resistance effect device 80 which are provided on the lower yoke so that the device is opposed to the lower end of rotating shaft 70 inserted into the through hole of said base plate with a slight gap, cover 90 attached to said support base 40, and casing 100 provided with base plate 10 which forms the external housing by being combined with said cover.

Base plate 10 is made of a non-magnetic material in the shape of lozenge and provided with a base plate fixing means such as, for example, two screw holes at both sides of its longitudinal direction.

Through hole 11 is provided at the center of base plate 10 and a cylindrical wall is provided along the circumferential direction in reference to the through hole, thus forming casing 100 which is open downward.

Upper yoke 20 is made of a magnetic material in the form of funnel which is open upward, provided with through hole 21 is opposed to the through hole of said base plate and is fixed to base plate 10 so that its open end contacts the lower surface of base plate 10 to cover the through hole of said base plate 10.

The fixing means for upper yoke 20 can be freely made. However, as shown in FIG. 2, screw 22 is generally employed. Low-friction bearing 10 provided with through hole 111 into which rotating shaft 70 is inserted is housed in the internal room of said upper yoke 20.

Bearing 110 can be made of a synthetic resin as shown in FIG. 2 or can be a bearing as shown in FIG. 6. Support base 40 employed as the pushing means in this embodiment is connected to upper yoke 20 as shown in FIG. 3 through coupling rod 30 such as a threaded rod, etc.

Accordingly, the distance between support base 40 and upper yoke 20 can be adjusted in accordance with the length of coupling rod 30 in the space formed between the upper yoke and the lower yoke.

Support base 40 is generally made in the form of disc; however, its shape can be freely changed in accordance with the shape of the casing and, as shown in FIG. 11, the shape can be rectangular depending on the case.

Protuberance 41 facing upward is provided at the center of support base 40 and is forced to contact the center of lower yoke 60.

Protuberance 41 can be spherical as shown in FIG. 2, can be stepped as shown in FIGS. 9 and 10 or can be an end of screw 41 which is inserted through the center of support base 40 and projected from the support base as shown in FIG. 6.

If screw 41 is employed, the height of the protuberance can be adjusted by rotating the screw.

Lower yoke 60 is mounted on support base 40 and at least one magnet 50 is positioned between lower yoke 60 and upper yoke 20.

As shown in FIG. 5, lower yoke 60 is made in a cross shape and coupling rod 30 is inserted into each space between extended arms 61.

Lower yoke 60, as shown in FIG. 8, can be a flat plate such as, for example, a disc-shaped plate. In this case, it is desirable to provide long through holes 62 along the circumferential direction into which coupling rods 30 are inserted.

One pole end of magnet 50 contacts each extended arm 61 of lower yoke 60 and the other pole end of this magnet 50 contacts the lower surface of upper yoke 20. The pole ends of magnet 50 contacting extended arms 61 provide the same polarity and accordingly the magnetic flux concentrates in rotating shaft 70.

A plural number of magnets 50 need not be employed; for example, one cylindrical magnet having the poles at its both ends can be employed as shown with a dotted line in FIG. 8.

In this case, it is desirable to employ a flat plate type yoke as shown in FIG. 7 as lower yoke 60. Rotating shaft 70 is entirely made of a magnetic material as shown in FIG. 2 or the part below the position which contacts the upper yoke is made of a magnetic material as shown in FIG. 6, accordingly, rotating shaft 70, lower yoke 60, magnet 50 and upper yoke 20 are combined to form the closed magnetic flux path.

The length of rotating shaft 70 projected into the casing is limited by stopper 71 so that the lower end at the insertion side is opposed to lower yoke 60 with a slight interval.

The inserted lower end of rotating shaft 70 is divided into semi-circular projected end 72 and semi-circular chipped portion 73 and the projected end eccentrically moves in reference the axis of the rotating shaft along with rotation of the rotating shaft.

Accordingly, the magnetic flux flowing in the magnetic flux path is concentrated into the gap formed between projected end 72 and lower yoke 60. As shown in FIG. 7, said projected end 72 can be made by connecting the magnetic shaft having a semi-circular section to the non-magnetic rotating shaft. Magnetro-resistance effect device 80 is fixed at the surface of lower yoke 60 opposed to the inserted free end of rotating shaft 70.

Device 80 is of the three-terminal type if the apparatus according to the present invention is a potentiometer. It is positioned on the circular surface of the lower yoke corresponding to the circle formed when projected end 72 meshes with chipped portion 73 and is formed so that a pair of symmetrical magnetism sensing surfaces are provided at both ends of the intermediate terminal.

The following describes this three-terminal type device 80 according to FIGS. 11 and 12.

Device 80 shown in FIG. 11 is made up by forming main part 81 of the device in the shape of a chipped circle and providing terminals 82 and 82' to be connected to power supply S at both ends and intermediate terminal 83 to be connected to load L at the intermediate position. In device 80, the resistance value of magnetism sensing surfaces 84 and 85 varies along with rotation of projected end 72 of rotating shaft 70 shown with a broken line and the output obtained from intermediate terminal 83 varies.

Device 80 shown in FIG. 12 is made up by series-connecting two meandering elements and combining magnetism sensing surface 84 of one element and magnetism sensing surface 85 of the other element as a pair.

Said three-terminal device is such that the resistance value of magnetism sensing surfaces 84 and 85 between two terminals changes alternately due to eccentric movement of projected end 72.

A device other than the device described above such as, for example, the two-terminals device as shown in FIG. 14 can be employed for this purpose. In this case, a device made in the semi-circular shape can be opposed to the projected end of rotary shaft and thus the resistance value between the terminals can be varied by eccentric movement of the projected end.

Each device is provided with short bar in order to the magnetism sensitivity as conventional device.

Cover 90 is attached to support base 40 with screw 42. Cover 90 is fitted to casing 100 to form the housing.

If support base 40 is made to be rectangular as shown in FIG. 11, screw hole 43 is provided at the center to attach cover 90 to the underside of support base 40, and screw holes 44 are provided at both ends, into which coupling rods 30 are inserted.

Thereupon, the pushing means need not be the support base. For example, as shown in FIG. 7, lower yoke 60 can be fixed to support frame 91 of cover 90 and lower yoke 60 can be pushed by inserting screw 41'.

The apparatus according to the present invention is as described above. Therefore, if the specified output characteristics are not obtained due to slight difference in the dimensions arising from inaccurate machining of a part such as the upper yoke, rotating shaft or magnet, improper magnetization, irregularity in the characteristic of the element, etc., the gap formed between device 80 and rotating shaft 70 can be reduced by making the pushing means push the center of lower yoke 40, that is, the device fixing position and the magnetic flux density applied to the device can be adjusted.

In order to increase the pushing force of said pushing means, support base 40 is raised by rotating coupling lever 30 in case of the embodiment shown in FIG. 2 and the projecting length of screw 41 can be increased by rotating screw 41 in case of the embodiment shown in FIG. 6. In the embodiment shown in FIG. 7, the lower yoke is pushed by rotating inserted end 41' of screw 40' at the outside of cover 90.

Accordingly, lower yoke 40 to be selected should be variable in its shape. Since adjustment of the gap is actually approximately 0.5 mm, it is not necessary to select a material with excellent flexibility for the lower yoke.

The gap is generally adjusted by reducing it. Therefore, in practical use, it is desirable to adjust the output while reducing the gap which has been set to be a little larger than the specified value in assembly.

Claims

What is claimed is:

1. A galvano-magnetro effect apparatus comprising:

a. a base plate provided with a through hole,

b. a magnetic upper yoke attached to the underside of said base plate,

c. a lower yoke which is arranged opposing to said upper yoke through a space,

d. a rotating shaft which is inserted into the through hole of said base plate so that its main part contacts said upper yoke and its lower end is positioned close to said lower yoke,

e. a projected end which is provided at the lower end of said rotating shaft so that is eccentrically moves in reference to the axis of the rotating shaft when the rotating shaft rotates,

f. at least one magnet which is positioned between said upper yoke and lower yoke,

g. a magnetro-resistance effect device which is provided at the lower yoke surface so that it is opposed to the lower end of said rotating shaft, and

h. a pushing means which pushes the device position of said lower yoke from the lower side,

wherein said rotating shaft has the part, below the position where it contacts said upper yoke, being made of a magnetic material so that said part is combined with upper yoke, lower yoke and magnet to form the closed magnetic path, said magnet is so arranged that one magnetic pole contacts the upper yoke and the other magnetic pole contacts the lower yoke and the magnetic flux can be concentrated into the gap formed between the projected end of the rotating shaft and the device, said device is provided with at least two terminals and is designed so that the area of the magnetism sensing surface between the terminals opposing to the projected end varies with eccentric movement of the projected end and said pushing means is devised so that the pushing force applied to the lower yoke is changed by pushing the device fixing part of said lower yoke toward the projected end.

2. An apparatus according to claim 1, wherein said pushing means is comprised of a support base, which is mounted with the lower yoke on its surface and is provided with a protuberance which contacts the lower surface of the device fixing part of the lower yoke, and a coupling rod which couples the support base to the upper yoke so that the length of the rod between the upper yoke and the support base can be changed.

3. An apparatus according to claim 2, wherein said protuberance is provided by forming spherically the surface of the support base on which the lower yoke is mounted.

4. An apparatus according to claim 2, wherein said protuberance is provided by forming with a step the surface of the support base on which the lower yoke is mounted.

5. An apparatus according to claim 1, wherein said pushing means is comprised of the support base on which the lower yoke is mounted and a screw which is screw-fitted into the support base so that the extreme end of the screw projected above the support base contacts the lower surface of the device fixing part of said lower yoke, and said projected end of said screw forms said protuberance.

6. An apparatus according to claim 1, wherein a screw is screw-inserted into the casing bottom which forms the housing in order to form said pushing means, and the pushing force to be applied to the lower yoke is varied by making the projected end of said screw contact the lower surface of the device fixing part of said lower yoke and varying the length of the screw in the housing.

7. An apparatus according to claim 1, wherein the lower yoke is shaped in a cross and the magnets are respectively mounted on the extended arms.

8. An apparatus according to claim 1, wherein one cylindrical magnet which is magnetized so as to have magnetic poles at both ends is positioned between the upper yoke and the lower yoke.

9. An apparatus according to claim 1, wherein the projected end of the rotating shaft is shaped in a semi-circular form.

10. An apparatus according to claim 1, wherein a three-terminal type device provided the input terminals, which are connected to the power supply, at both ends and the intermediate terminal, which is connected to a load, at the center, is fixed at the lower yoke, and said device is devised so that the magnetism sensing surfaces between said intermediate terminal and input terminals oppose alternately to said semi-circular projected end of the rotating shaft during rotation of said shaft.