US3845929A

US3845929A - Stabilizing mechanism

Info

Publication number: US3845929A
Application number: US00195879A
Authority: US
Inventors: J Reekie; M Royston
Original assignee: Bell and Howell Co
Current assignee: Bell and Howell Co
Priority date: 1969-06-10
Filing date: 1971-11-04
Publication date: 1974-11-05
Anticipated expiration: 1991-11-05

Abstract

A mass is supported in a frame free from gravitational influence by spring means so that translatory frame movement of low frequency will be transmitted to said mass while translatory frame movement at or above a predetermined high frequency will be isolated from said mass. The spring means defines a pair of intersecting axes about which the mass is adapted to vibrate when the spring tensions because of high frequency translatory frame movements. Magnetic means, however, resist return of the mass to a balanced condition from an unbalanced condition which the mass assumes when the spring is tensioned, thereby to lower the inherent vibratory frequency of the mass to a value below the predetermined high frequency.

Description

Gross........

Primary Examiner.l. Franklin Foss Attorney, Agent, or Firm-John L. Cline [57] ABSTRACT A mass is supported in a frame free from gravitational influence by spring means so that translatory frame movement of low frequency will be transmitted to said mass while translatory frame movement at or above a predetermined high frequency will be isolated from said mass. The spring means defines a pair of inter- 350/ l 6 G02b 23/02 secting axes about which the mass is adapted to vibrate when the spring tensions because of high fre- 74/5 F; quency translatory frame movements. Magnetic means, however, resist return of the mass to a balanced condition from an unbalanced condition which the mass assumes when the spring is tensioned,

thereby to lower the inherent vibratory frequency of the mass to a value below the predetermined high frequency.

11 Claims, 9 Drawing Figures Inventors: James Reekie, Arcadia, Calif;

Marvin F. Royston, Skokie, 111.

Assignee: Bell 82 Howell Company, Chicago,

Filed: Nov. 4, 1971 Appl. No: 195,879

Related US. Application Data Continuation of Ser. No. 831,974, June 10, 1969, abandoned.

U.S. 248/358 R,

References Cited UNlTED STATES PATENTS 9/1954 Jensen ilnite States Patent Reelrie et a1.

1 1 STABllLlZlNG MECHANISM [58] Field of Search...........

a A P m w 4/1958 Jensen............. 7/1958 Werner........... 3,013,464 12/1961 Keuffel et a1.

STABILIZING MECHANISM This is a continuation of application Ser. No. 831,974 now abandoned, filed June 10, 1969 by express abandonment.

The present invention relates to stabilizing mechanisms. Particularly, the invention relates to means for filtering out high frequency angular motions, while at the same time passing or transmitting motions of low frequency. Specifically, the invention is adapted for, but not limited to, stabilization of optical instruments, such as cameras and binoculars of the type which are ordinarily hand-held when used.

In optical systems having a stabilizer, a coupling or mount connects a lens (a mass with a high moment of inertia) with a frame for transmitting translatory frame movement of low frequency to, while isolating high frequency translatory frame movement from, the lens. As a result, a field of view of a hand-held instrument can be changed by moving the frame, in a customary manner for that purpose, inasmuch as such movement is of low frequencysln contrast, normal trembling hand motion, being of high frequency, will be filtered out or isolated from the lens to prevent movement.

Heretofore known stabilizers of the indicated type may be divided into two classes. A first, exemplified by U.S. Pat. No.'3,25 l ,262, is characterized in that a lens is pendulously mounted in its casing or. frame, relying on gravitational influence, to produce desired orienta tion. The other, the class with which the present invention is concerned, is characterized in that a mass of high inertial movement is independent of gravitational influence and tends to assume a fixed or balanced relationship with respect to a frame in which it is mounted. It is exemplified by US Pat. No. 2,688,456.

In heretofore known devices of the last mentioned class, a gimbal couples the mass and frame to enable movement of each mass about intersecting axes. While such mechanisms are satisfactory in effecting stabilization. the cost of providing required fine bearings limits their widespread use. Particularly, in popularly priced cameras and binoculars, and the like, use of heretofore known stabilizing mechanisms is unknown.

It is an object of the present invention to provide an improved stabilizing mechanism.

It is another object of the invention to provide a stabilizing mechanism enabling translatory frame movements of low frequency readily to be transmitted to a mass for moving the latter with the frame, while isolating high frequency angular movement of the frame from the mass.

It is a further object of the invention to provide in optical instruments such as cameras and binoculars, a means for stabilizing a lens system against high frequency translatory frame movement which will be efficient in use, durable and which can be produced for a reasonable cost.

Yet further. it is an object of the invention to provide an improved optical device.

An additional object of the invention is provision of improved binocular construction.

Moreover, it is an object of the invention to provide an improved camera construction.

To effect the foregoing objects, for a mass with a high movement of inertia, there is provided elastic means in a stabilizing mechanism to: (a) balance the mass against gravitational influence, and in a fixed condition for movement relative a frame; and (b) constrain the mass for movement with said frame when said frame is moved angularly at low frequency. The elastic means are connected to the frame and tensionally support the mass for harmonic-like movement about a pair of axes when the rate of translatory frame movement is at a high frequency.

Further and other objects of the invention will be apparent from the description of the accompanying drawings, in which like numerals refer to like parts.

In the drawings:

FIG. 1 is a perspective of one embodiment of the invention, incorporated in a camera, parts of which have been broken away;

FIG. 2 is a sectional view taken on the lines 2-2 of FIG. 1;

FIG. 3 is a top plan of an embodiment of the invention modified from FIG. 1 and incorporated in a camera shown partially, in section;

FIG. 4 is a perspective of yet another embodiment of said invention incorporated in a camera, parts of which are broken away;

FIG. 5 is a perspective of elastic means of yet another embodiment of said invention;

FIG. 6 is a perspective of a modification of the invention embodied in binoculars, portions of which have been broken away;

FIG. 7 is a sectional view taken on the lines 77 of FIG. 6;

FIG. 8 is a detailed sectional view taken .on the lines 8-8 of FIG. 7; and

FIG. 9 is a sectional view taken on the lines 9-9 of FIG. 6.

Referring now more particularly to FIG. 1, a stabilizing mechanism generally designated 10 is adapted for an optical instrument such as a camera having an outer housing or casing shown in dashed lines and referred to generally as frame 12. The mechanism is adapted to balance a mass 14 with a high moment of inertia against gravitational influence and in a fixed condition for movement relative said frame when translatory frame movement having certain angular characteristics is of high frequency. Moreover, the mechanism is adapted for transmitting translatory frame movements to said mass for its movement with said frame when the rate of such movement, in selected angular directions, is of low frequency.

Elastic means, herein shown as spring 16, has a frame proximate portion 15 and a portion 17 opposed thereto. Spring portion 15 is connected to frame 12 through the agency of a block 13 (shown in phantom) which is fixed to said frame. The mass is supported from portion 17 and thereby coupled to the frame for harmonic-like movement about a pair of axes Y and P, when the rate of translatory frame movement is at a high frequency.

For the various illustrated devices, low frequencies are less than about a half cycle per second, while high frequencies are upwards of one cycle per second. The customary vibratory rate of trembling human hands in in the range of l to 20 cycles per second. Angular motion of high frequency desired to be isolated from the illustrated optical systems are yaw-like (about vertical axis Y) and pitch-like (about horizontal axis P). High frequency roll-like motions about horizontal axis R, which defines the fixed optical axis of the systems shown in FIGS. 1, 3 and 4 are of no consequence, be cause they do not change the distance of the lens comprising mass 14 from a subject with respect to which a system is normally oriented during use.

Spring 16 defines the Y and P axes which intersect in said spring at a point 25 about which the mass 14 is adapted to move relative to said frame through the agency of an elongated mount generally designated 18. The spring is fashioned for vibratory movement about the P and Y axes, respectively. In consequence. point 25 comprises the center of movement of mass 14. A medial section 19 of said mount is rigidly secured to spring portion 17, and a pair of mount projections or

extensions

20 and 22 extend in opposite directions from medial section 19. Mass 14 is secured from an outer end portion of extension 20.

In each of the embodiments of FIGS. 1, 2 and 3, mass 14 comprises a movable convex lens or optical wedge 24 whose center of curvature is defined by point 25. A concave lens 26 is fixed to frame 12 as the forward element of the optical system in each of FIGS. 1, 3 and 4, in a manner such that the optical centers of

lenses

24 and 26 are disposed on axis R when the parts are not in motion. The center of curvature of lens 26 also is point 25, and said lens is slightly spaced from lens 24 and therewith forms a doublet.

In consequence of the foregoing arrangement, adjoining faces of

lenses

26 and 24 are concentrically disposed so that upon their relative movement they will remain uniformly spaced at all positions of relative angular movement. Further comprising the optical systems of FIGS. 1, 3 and 4, however, omitted from FIG. 4 to minimize crowding of the view, is a focusing lens 28 fixed in frame 12 by any suitable means, between lens 24 and the focal plane of the camera. Lens 28 is centered about axis R for impinging an image on frame 30 of filmstrip 32 carried in said focal plane.

To limit relative movement between mass 14 and frame 12, an abutment member 34 is secured to the frame and has an opening 36 through which mount 18 loosely extends. A coun terwieght 40, (omitted from FIGS. 1 and 4) is adjustably mounted for movement longitudinally of section 22 of mount 18 for effecting a condition in which mass 14 is balanced in or fixed relative to frame 12 at any fixed angular aspect of said frame. That balancing is effected by moving the center of gravity of the total suspended mass to a point coincident with the intersection of axes P and Y.

While mounts 18 of FIGS. 1 and 3 are mechanical equivalents. mount

sections

20 and 22 in FIG. 1 are shown aligned and disposed on a common side of spring 16. An arm 42, fashioned integrally with said mount projects normally from the juncture of said sections and is rigidly secured to spring end portion 17. In FIG. 3,

sections

20 and 22 are parallel. being disposed on opposite sides of spring 16. An integral medial mount portion 44, which itself is rigidly secured to spring 16, connects said sections.

In the embodiment of FIGS. 1 and 3, spring 16 is fashioned as a band which projects normally away from its position of securance to frame 12. The spring has a longitudinally extending medially disposed rigidifying welt or rib 46 (FIG. 2) fashioned for limiting rotation of mass 14 about desired axes.

In FIG. 4, the equivalent of mount 18 is an elongated structure 48 of cage-like fashioning. It has a pair of oppositely extending

end sections

50 and 52 which are equivalent to

sections

20 and 22. A ring 54 centered about the optical axis of lens 26 defines a medial section of said mount. A pair of diametrically

opposed straps

56 and 58 which comprise structure 48 are integral with said ring and extend transversely thereof. The ring distal end portions of

straps

56 and 58 which define section are secured to opposite sides of lens 24. The portions of said straps which form section 50 also project through a ring 60 which is disposed between lens 24 and ring 54, said ring 60 being slightly spaced from ring 54 and concentric with the optical axis.

Four

radial extensions

62, 64, 66 and 68 are disposed angularly from each other 90 and define two sets which are disposed normally to each other and project outwardly from ring 60. The set comprising extensions 64 and 68 are secured to frame 12 through the agency of a pair of parallel

flat springs

70 and 72 which define a plane. The latter are band-like and each has an end secured to corresponding of extensions 64 and 68. Each of said springs has an opposite end secured to a corresponding of a pair of

blocks

74 and 76 which themselves are fast to frame 12. The arrangement is such that springs 70 and '72 define an axis for pitch-like movement of the frame.

A pair of

flat springs

78 and 80 in the form of bands have commonly directed ends connected to the set comprised of

extensions

62 and 66, respectively, and oppositely directed ends which are secured to a respective of a pair of extensions 82 and 84. The latter project diametrically outwardly from ring 54 in alignment with

extensions

62 and 66, respectively, to define the Y axis about which lens 24 is movable in a yaw-like mode.

Springs

78 and 80 lie in a common plane normal to the plane in which springs 70 and 72 are disposed; and all of said springs extend longitudinally of the longitudinal axis of mount 48, parallel to the optical axis and to each other and comprise elastic means of gimbal-like character equivalent to spring 16.

In the embodiment of FIG. 5, the elastic means comprises a flat annular member 84 having four

radial springs

86, 88, and 92, fashioned as spokes or flat bands which are shortened by omitting their center sections. The springs are disposed in a common plane and have outer wide sections which are integrally fashioned with the annular periphery of member 84. The springs are arranged in diametrically spaced apart sets or pairs, said sets or pairs being normal to each other. The inner narrow ends of said springs are rigidly secured to a ring 94, which is centered about optical axis R and disposed within and concentric with the outer periphery or annulus of member 84. Ring 94 comprises a medial section of an elongated mount for lens 24, the opposite end sections of such support having been omitted from FIG. 5. At diametrically opposed positions in alignment with the set comprised of

springs

86 and 90, the outer annulus of member 84 is anchored by a pair of suitable fasteners to frame 12.

Member 84 is disposed at an angular aspect about optical axis R and fashioned in a manner such that springs 86 and 90 define the P axis, while

spring members

88 and 92 define the Y axis.

The construction and arrangement of the member 84 as well as spring 16 and its equivalent of FIG. 4 is such that all angular frame movement, regardless of frequency, about optical axis R, will be transmitted to mass 24. However, each elastic means will become tensioned upon angular frame movement of high frequency about the Y and P axes, in consequence of which its associated mass will tend to vibrate at an inherent frequency about the spring or springs comprising such elastic means. The tensioning results from the inertia induced tendency of the mass to remain station. ary despite frame movement.

Means generally designated 96 are provided for resisting the tendency of the mass to vibrate at its inherent period and provide a long normal period and low frequency for the system. The definition of low" and high frequencies will vary from one application to another. As previously noted in a movie camera application high means one cycle per second and above, and low" means anything below one cycle per second. The resisting means may be spring-like in character. In the illustrated embodiments, the resisting means comprises a pair of permanent magnets herein shown in alignment. A first magnet 98 is rigidly secured to its respective mount in a position which may, but not necessarily need be, opposed from mass 14. The other magnet 100 of each pair is rigidly secured to frame 12. As illustrated in FIGS. 1 and 4, a bracket 102 which is secured to said frame may be employed for holding magnet 100.

Magnets

98 and 100 are slightly spaced each from the other, with like poles in facing association. Moreover, the arrangement of the magnets is such that the repelling force generated in the magnetic field does not significantly displace the mass from its balanced or fixed condition, i.e., when the elastic means is untensioned.

However, the magnets are proportioned and arranged in a fashion such that once the elastic means is tensioned, that is to say, once the optical axis of lens 24 is displaced from its fixed condition or balanced condition along axis R to an unfixed or unbalanced condition along axis R (FIG. 3), the magnetic field will resist the tendency of the mass to vibrate around axes Y and P, and the mass will slowly return at a low frequency to its balanced position and thereby minimize any distortions due to relative vibrations of lens 24 and a field on which the camera is trained. Accordingly, translatory vibrations of high frequency imposed on frame 12 are effectively isolated from lens 24 and will only slightly affect it. It is appreciated that the vibration resisting force of the magnetic field when the magnets are disaligned can be adjusted according to size, spacing and magnetic characteristics of said magnets.

A caging mechanism generally designated 104 (FIGS. 1 and 6) has been omitted from FIGS. 3 and 4. It is arranged for locking the mass in its fixed or balanced position when the apparatus in connection with which such caging mechanism is employed is not in use. To that end, an elongated pin or plunger 106 is mounted for slidable movement longitudinally of its axis. The plunger has a tapered head 108 on its inner end to facilitate entry into an aligned receiving hole or seat 110 in the mount for the mass. A bracket 112, which is fixed to frame 12, slidably supports plunger 106 with head I08 normally disposed in the hole 110 to lock the mount to the frame. Means for urging the pin into its normal condition comprises a coil spring 114 which is mounted about the pin with its opposite ends bearing against a collar 116, carried on said pin, and an arm 118 of bracket 112. The pin is arranged so that a projection of its longitudinal axis intersects center 25, thereby precluding tensioning of the elastic means when the caging mechanism is in locking conditron.

An extension 120 of said pin slidably projects outwardly through arm 118 and engages a manually rockable control member 122 which is disposed about said extension between bracket arm 118 and a limiting collar 124 secured on the outermost end of said arm. Control member 122 is pivotably mounted for movement about an axis pin 126 between its normal or caged condition to which it is drawn by spring 114 and a tensioned condition in which it is limited by adjustable stop 128 to unseat head 108 from hole 110 and liberate the mount. A manual component 130 disposed outside of frame 12 is arranged to rock control member 122 for withdrawing head 108 against tension of spring 114.

The invention is also adapted for binoculars 132 (FIG. 6), here shown comprising housing means defining a pair of lens barrels or compartments 136 and 138 in the forward ends of which there are mounted a pair of

lenses

140 and 142. An outer hand grippable structure, casing or shroud comprises a frame 144 which may be of less mass than the binocularsand is disposed about said housing means.

Elastic means comprising spring 16 is connected to frame 144through the agency of a block 146. The latter is fast to the frame and disposed between

compartments

136 and 138. A clamp 148 fastens spring 16 to block 146 by suitable fasteners such as screws. In FIG. 6, the opposite end of spring 16 is clamped to a boss 150. A mount or coupling 152 is adjustably secured to said boss by a screw 168 for connection to said spring.

Coupling 152 is an elongated member extending longitudinally of the optical axes of

lenses

140 and 142 for vibratably supporting the housing means relative to frame 144, independent of gravitation influence. To

that end, an extension 154 from a medial part of said coupling is rigidly connected to the housing through the agency of a connecting rod 156, which is parallel to coupling 152 and disposed between

compartments

136 and 138. Opposite ends of said connecting rod are connected to a pair of

parallel ties

158 and 161, which are disposed transversely of rod 156 for coupling the

binocular compartments

136 and 138 together in spaced-apart relationship. As illustrated, each crosspiece may be an assembly of conventional design of a pair of overlapped extensions arranged from said compartments to permit rocking of one compartment relative the other about an axis defined by rod 156 to vary compartment spacing.

From the foregoing, it is seen that the binoculars 132 comprise a mass which is hung from spring 16 through the agency of mount or coupling 152 and said binoculars is mechanically equivalent to mass 14 heretofore described.

Extension 154 has a hole 160, distal coupling 152 and into which a pin 162 of smaller diameter than said hole projects. The pin is carried from a bracket or block 164 which is rigidly secured to the frame 144. The wall, defining hole 160, thereby limits movement of binoculars 132 and coupling 152 relative to frame 144.

To balance coupling 152 in a fixed or normal condition relative to frame 144 free from gravitational influence, boss has a slot 166 in which screw 168 is ad- 65 justably disposed for releasably securing said coupling manent magnets 170 and 172 which are coaxially aligned and have like poles in facing and slightly spaced association one from the other when the mass is wholly balanced or in its fixed position. Magnet 170 is carried in a block 174 which is secured by suitable means to frame 144. Magnet 172 projects outwardly from an end section 176 of coupling 152. Magnets 170 and 172 are proportioned and arranged for holding coupling 152 in its balanced condition, but for resisting return to said balanced condition once it is upset. Thereby high frequency movement of binoculars 132 is precluded when frame 144 is moved at a high frequency.

Coupling 152 can be fashioned to accommodate caging mechanism 104 by providing a cutout 178 into which portions of the caging bracket extend. A hole 180 (FIG. 7) provided in coupling 152 defines a seat for head 108 of said caging mechanism. A control member corresponding to member 122 has been omitted from FIG. 6 to minimize obscuring of other essential detail.

Although magnetic means 96 is effective for frequency control of the mass, a suitable damping agent 182 (FIG. 6) for controlling amplitude of oscillations also may be provided. The exemplary damping agent comprises a viscous damping mass in the form of a silicon rubber band which has one end anchored on frame 144 and its opposite end anchored on coupling extension 154.

While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope thereof.

What is claimed is:

l. A stabilized mass system comprising:

a frame member;

a mass;

elastic means mounting said mass to said frame member for vibration about an axis at an inherent vibratory frequency;

said mounted mass having a rest position relative to said frame member and said elastic means applying a return torque to said mounted mass to return said mounted mass to said rest position when said mounted mass is displaced from said rest position, said return torque being substantially zero when said mounted mass is at said rest position and increasing in magnitude as said mounted mass is displaced from said rest position; and

means for applying a torque to said mounted mass in opposition to said return torque, said opposing torque being substantially zero when said mounted mass is at said rest position and increasing in magnitude as said mounted mass moves away from said rest position during said vibratory motion about said rest position. thereby reducing said inherent vibratory frequency of said mounted mass.

2. A mass system stabilized with respect to a frame during vibration of said frame that comprises:

a frame capable of being vibrated;

a band spring mounting a mass system to said frame for rotation about an axis;

a first magnet mounted on said mass system; and

a second magnet mounted on said frame;

said first and second magnets being disposed such that when the mass system is at rest like magnetic poles are in facing relationship and such that they apply a torque to said mounted mass in opposition to said spring and, said opposing torque being substantially zero when said mounted mass is at said rest position and increasing in magnitude as said mounted mass moves away from said rest position during said vibratory motion about said rest position, thereby reducing said inherent vibratory frequency of said mounted mass. I

3. A system for stabilizing a mass connected to a frame during vibration of said frame at or above a high frequency comprising:

a frame member capable of being vibrated at or above a predetermined high frequency; a mass; elastic means mounting said mass to said frame for vibration about an axis, said mounted mass having a high vibratory frequency; and

means for applying a torque to said mounted mass in opposition to said elastic means, said opposing torque being substantially zero when said mounted mass is at said rest position and increasing in magnitude as said mounted mass moves away from said rest position during said vibratory motion about said rest position, thereby reducing said inherent vibratory frequency of said mounted mass.

4. A system for stabilizing a mass mounted to a member during vibration of the member at or above a predetermined high frequency about a pair of substantially intersecting axes comprising:

a member capable of being vibrated at or above said high frequency;

a mass system;

elastic means mounting said mass system for vibratory movement about said pair of substantially intersecting axes;

said mounted mass system having an inherent harmonic vibratory frequency about each of said axes at least as high as said predetermined high frequency;

said mounted mass system being so disposed that the center of gravity thereof is substantially coincident with the point of intersection of said axes when said mounted mass system is in equilibrium position with respect to said member; and

modifying means for applying a torque to said mounted mass in opposition to said elastic means, said opposing torque being substantially zero when said mounted mass is at said equilibrium position and increasing in magnitude as said mounted mass moves away from said equilibrium position during said vibratory motion about said equilibrium position, thereby reducing said inherent vibratory frequency of said mounted mass.

5. The system set forth in claim 4, wherein said modifying means comprises a first magnet mounted on said mass system and a second magnet mounted on said frame. said magnets being disposed such that when said mass system is at rest like poles face one another.

6. The system set forth in claim 4 wherein said elastic means is a band spring having one end fixed to said frame and the other end fixed to said mass system, said spring being capable of flexure about both the longitudinal axis of said spring and a second axis that is perpendicular to and intersects said longitudinal axis.

7. The system set forth in claim 6 wherein said modifying means comprises a first magnet mounted on said mass system and a second magnet mounted on said frame, said magnets being disposed such that when said mass system is at rest like poles face one another.

8. The system set forth in claim 4 wherein said elastic means comprises a first pair of band springs mounted at one end to said frame and at the other end to a ring for flexure about a first axis; and a second pair of band springs mounted at one end to said ring and at the other end to the remainder of said mass system for flexure about a second axis.

9. The system set forth in claim 8 wherein said modifying means comprises a first magnet mounted on said mass system and a second magnet mounted on said member, said magnets being disposed such that when said mass system is at rest like poles face one another.

said mass system is at rest like poles face one another. l =l

Claims

1. A stabilized mass system comprising: a frame member; a mass; elastic means mounting said mass to said frame member for vibration about an axis at an inherent vibratory frequency; said mounted mass having a rest position relative to said frame member and said elastic means applying a return torque to said mounted mass to return said mounted mass to said rest position when said mounted mass is displaced from said rest position, said return torque being substantially zero when saId mounted mass is at said rest position and increasing in magnitude as said mounted mass is displaced from said rest position; and means for applying a torque to said mounted mass in opposition to said return torque, said opposing torque being substantially zero when said mounted mass is at said rest position and increasing in magnitude as said mounted mass moves away from said rest position during said vibratory motion about said rest position, thereby reducing said inherent vibratory frequency of said mounted mass.

2. A mass system stabilized with respect to a frame during vibration of said frame that comprises: a frame capable of being vibrated; a band spring mounting a mass system to said frame for rotation about an axis; a first magnet mounted on said mass system; and a second magnet mounted on said frame; said first and second magnets being disposed such that when the mass system is at rest like magnetic poles are in facing relationship and such that they apply a torque to said mounted mass in opposition to said spring and, said opposing torque being substantially zero when said mounted mass is at said rest position and increasing in magnitude as said mounted mass moves away from said rest position during said vibratory motion about said rest position, thereby reducing said inherent vibratory frequency of said mounted mass.

3. A system for stabilizing a mass connected to a frame during vibration of said frame at or above a high frequency comprising: a frame member capable of being vibrated at or above a predetermined high frequency; a mass; elastic means mounting said mass to said frame for vibration about an axis, said mounted mass having a high vibratory frequency; and means for applying a torque to said mounted mass in opposition to said elastic means, said opposing torque being substantially zero when said mounted mass is at said rest position and increasing in magnitude as said mounted mass moves away from said rest position during said vibratory motion about said rest position, thereby reducing said inherent vibratory frequency of said mounted mass.

4. A system for stabilizing a mass mounted to a member during vibration of the member at or above a predetermined high frequency about a pair of substantially intersecting axes comprising: a member capable of being vibrated at or above said high frequency; a mass system; elastic means mounting said mass system for vibratory movement about said pair of substantially intersecting axes; said mounted mass system having an inherent harmonic vibratory frequency about each of said axes at least as high as said predetermined high frequency; said mounted mass system being so disposed that the center of gravity thereof is substantially coincident with the point of intersection of said axes when said mounted mass system is in equilibrium position with respect to said member; and modifying means for applying a torque to said mounted mass in opposition to said elastic means, said opposing torque being substantially zero when said mounted mass is at said equilibrium position and increasing in magnitude as said mounted mass moves away from said equilibrium position during said vibratory motion about said equilibrium position, thereby reducing said inherent vibratory frequency of said mounted mass.

5. The system set forth in claim 4, wherein said modifying means comprises a first magnet mounted on said mass system and a second magnet mounted on said frame, said magnets being disposed such that when said mass system is at rest like poles face one another.

10. The system set forth in claim 4 wherein said elastic means comprises two pair of diametrically opposed springs that are mounted at one end to said frame and at the other end to said mass system for flexure about said pair of mutually perpendicular intersecting axes.

11. The system set forth in claim 10 wherein said modifying means comprises a first magnet mounted on said mass system and a second magnet mounted on said member, said magnets being disposed such that when said mass system is at rest like poles face one another.