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Publication numberUS3864586 A
Publication typeGrant
Publication dateFeb 4, 1975
Filing dateSep 13, 1973
Priority dateSep 14, 1972
Also published asCA977161A1, DE2346397A1
Publication numberUS 3864586 A, US 3864586A, US-A-3864586, US3864586 A, US3864586A
InventorsSaito Hiroshi
Original AssigneeSeikosha Kk
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Vibrator and vibratory system
US 3864586 A
Abstract
A vibrator comprises a vibratory unit composed of resilient sheet material and having two main vibratory arms disposed in spaced parallel relationship and interconnected at their ends by two connecting end portions. A pair of central vibratory arms extend inwardly from each connecting end portion in a direction towards each other and the central arms and the main arms all lie in a common plane. The vibratory system comprises the vibrator in combination with a driving magnet connected to one of the central arms thereof and a driving coil coacting with the driving magnet to alternately drive same to effect flexural vibration of the central arm accompanied by vibration of the main vibratory arms. A driven magnet is connected to either the same central arm or the other central arm of the vibrator and coacts with a magnetic follower wheel to rotationally drive the follower wheel in an intermittent manner in accordance with the vibratory motion of the main vibratory arms.
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Description  (OCR text may contain errors)

D United States Patent [in [H] 3,864,586

Saito l l Feb. 4, 1975 VIBRATOR AND VIBRATORY SYSTEM Primary Examiner-Donovan F. Duggan Attorney, Agent, or Firm-Robert E Burns; [75] Inventor. lliroshl SaIto, Omiya, Japan Emmanual J- Labam; Bruce L Adams [73] Assignee: Kabushiki Kaisha Seikosha, Tokyo,

Japan {57] ABSTRACT [22] Filed: Sept. 13, I973 A vibrator comprises a vibratory unit composed of re silient sheet material and having two main vibrator [2]] Appl' 396675 arms disposed in spaced parallel relationship and in terconnected at their ends by two connecting end por- [30] Foreign Application Priority Data tions. A pair of central vibratory arms extend inwardly seph 14 972 Japan H 471M301 from each connecting end portion in a direction to- Oct 20, 1972 Japan H 47405064 wards each other and the central arms and the main arms all lie in a common plane. The vibratory system 52 us. Cl 310/21, 310/22, 310/25, comprises the vibrator in Combination with a driving 58/23 v 58/23 D magnet connected to one of the central arms thereof 51 Int. Cl. H02k 7/06 and a driving coming with the driving magnet to 5 pick f Search 310/21 25 58/23 R, alternately drive same to effect flexural vibration of 53 23 TF 23 v 23 34 409 457; 331 15 the central arm accompanied by vibration of the main vibratory arms. A driven magnet is connected to ei- 5 References Cited ther the same central arm or the other central arm of UNITED STATES PATENTS the vibrator and coacts with a magnetic follower wheel to rotationally drive the follower wheel in an ina il termittent manner in accordance with the vibratory 314913257 1/1970 ogie' 'fffIIIIIIIIIIIIIIIIIIIIIIIII 310/25 X move of the main vibratory 9 Claims, 12 Drawing Figures PATENTED 3.864.586

SHEH 20F 4 PATENTED H975 3.864.586

sum 30? 4 1 VIBRATOR AND VIBRATORY SYSTEM The present invention relates generally to mechanical vibrators and more particularly, to a mechanical vibrator especially designed for use in a timepiece or as a mechanical filter.

Various types of mechanical vibrators are known in the art and of the various types, the tuning fork vibrator has proven to be especially suitable and reliable for use in timepieces. One type of tuning fork which is widely used in the art has three tines or prongs and has a driving magnet secured to the free end of the central tine and a set of weighting or balancing masses affixed to the free ends of the other two tines. The central tine moves through an arc of a circle during use of the vibrator and consequently, sufficient clearance must be provided between the path of travel of the driving magnet and the interior of the driving coil.

Since the driving magnet undergoes pivotal movement into and out of the interior ofthe driving coil, sufficient clearance space must be left between the innermost turns of the coil and the angular path of travel of the driving magnet so as to preclude collision between the two and such an arrangement results in a low driving efficiency of the vibrator due to the comparatively wide air space. Furthermore, such a tuning fork vibrator is of the cantilever type wherein all the vibratory arms are secured at one end to a support and are free at their other ends and this type of vibrator readily undergoes vibrational mode changes and is susceptible to vibrating in spurious vibrational modes rather than the intended normal vibrational mode.

The present invention eliminates the aforementioned disadvantages of the conventional tuning fork vibrator. The vibrator of the invention is composed of resilient sheet material and has two main vibratory arms which are interconnected at their ends by respective connecting end portions and the vibrator has two central vibratory arms which each project inwardly from one of the connecting end portions towards each other and terminate in spaced opposed relationship from each other. A driving magnet is secured to one of the central arms and is magnetically driven during use of the vibrator to vibrate the central arm and accordingly vibrate the two main vibratory arms in a predetermined normal vibrational mode.

During operation of the vibrator, the free end of the driven central arm pivots about the corresponding connecting end portion of the vibrator and once the main vibratory arms begin to vibrate, they in turn pivot about a pivot located at the other connecting end portion and as a result of the different directions of pivotal movement of the central arm and the main arms, the driving magnet undergoes substantially linear alternating movement. Thus the hollow driving coil which is used to electromagnetically drive the magnet may be disposed very close to the path of travel of the magnet thereby increasing the driving efficiency of the vibratory system.

It is therefore a primary object of the present invention to provide an improved vibrator and vibratory system which overcome the drawbacks described above with respect to the prior art systems.

It is another object of the present invention to provide an improved vibrator and vibratory system utilizing a plurality of vibratory arms which are dimensioned and arranged in such a manner to sustain vibration in a normal vibrational mode at a high driving efficiency.

It is still another object of the present invention to provide an improved vibrator and vibratory system employing a pair of main vibratory arms which are interconnected at both ends to each other and which has a pair of central arms extending inwardly towards each other such that a driving magnet affixed to one of the central arms undergoes vibration in essentially a linear direction.

Other features and advantages of the vibrator and vibratory system constructed in accordance with the principles of the invention will be better understood upon a reading of the following specification and appended claims when taken in conjunction with the following drawings, wherein like parts are designated by like reference characters in the various views, and wherein:

FIG. I is a plan view of one embodiment of a vibrator constructed in accordance with the principles of the invention;

FIG. 2 is a plan view of the vibrator shown in FIG. I along with additional components which make up the vibratory system;

FIG. 3 is a sectional view taken along lines IIIIII in FIG. 2;

FIG. 4 is a right side view of the vibratory system shown in FIG. 2;

FIG. 5 is one embodiment of an electric drive circuit usable with the vibrator of the invention;

FIG. 6 is another embodiment ofan electric drive circuit for use in driving the vibrator of the invention;

FIGS. 7A and 7B are explanatory diagrams depicting the normal vibrational mode of the vibrator;

FIG. 8 is a series ofexplanatory diagrams comparing the normal vibrational mode with the spurious vibra tional modes;

FIG. 9 is a plan view of another embodiment of a vibratory system according to the invention;

FIG. 10 is a sectional view taken along the section line XX in FIG. 9; and

FIG. 11 is a right side view ofthe embodiment shown in FIG. 9.

The vibrator comprises a vibratory unit 1 composed of resilient sheet material having a constant modulus of elasticity. The vibratory unit I has a pair ofmain vibratory arms 2,2 which extend in parallel and spacedapart relationship and which are interconnected at one end by a connecting end portion 3 and at the other end by another connection end portion 4. A pair of central vibratory arms 5 and 6 are connected to respective ones of the connecting end portions 3 and 4 and extend inwardly towards each other as shown in FIG. 1. The dis tal ends of these central arms 5 and 6 are spaced-apart from each other to enable the arms to move independently of each other.

A pair of supporting arms 7 and 8 extend outwardly from the connecting end portion 4 and the supporting arms are connected to a fastening portion 9. A pair of holes 10,10 are provided in the fastening portion 9 and by such a construction, the vibratory unit is fastened to and supported upon a suitable support member during use of the vibratory unit.

As shown in FIGS. 24, the vibratory system comprises a support member 13 having a bracket portion 12 which is affixed to the vibratory unit I by a pair of screws 1],". The mounting of the vibratory unit I upon the support member 13 is such that the unit vibrates about the supporting arms 7 and 8 which comprise fixed nodal points.

A driving magnet 14 is affixed to the free end of the central vibratory arm by means of a supporting member 15. The driving magnet 14 has a cylindrical contig uration and is supported so as to extend perpendicularly with respect to the plane of the vibratory unit 1 and the longitudinal axis of the driving magnet lies along a center line L. An adjusting screw 16 is threaded into the supporting member and the screw is selectively threaded into or out of the supporting member to accordingly regulate the frequency of vibration of the vibrator.

A base plate 19 is disposed beneath the vibrator and spaced-apart therefrom by means of the supporting member 13. A hollow spool 17 is affixed to the base plate 19 and the spool has a cylindrical throughbore which is concentric with the center line L and which is dimensioned to receive therein the driving magnet 14. The spool l7 is composed of electrically insulative material and a pickup-and-driving coil 18 is wound around the spool in such a manner that energization of the coil creates a magnetic field of sufficient strength to drive the magnet 14 in one direction and when the coil is de energized, movement of the magnet 14 past the coil induces a voltage therein in a manner well known in the art.

A driven magnet 20 is secured to the other side ofthe central arm 5 by means of a supporting member 21. As seen in H08. 3 and 4, the driven magnet 20 is mounted along the center line L and the magnet 20 has the configuration on a yoke having two generally parallel arms which are connected at one end to the supporting member 21 and which terminate at their other ends in a pair of arm extensions 22,22. The arm extensions ex tend toward each other and are spaced-apart to define a small gap therebetween. A magnetic follower wheel 23 is mounted for rotation adjacent the yoke such that the periphery of the follower wheel passes through the gap and the arm extensions 22,22 function as magnetic poles and coact with the follower wheel 23 to rotationally drive same in an intermittent manner in response to vibration of the vibratory unit 1.

As seen in FIG. 3, the follower wheel 23 has a plurality of circumferentially spaced-apart peripheral teeth 24 and a corresponding plurality of apertures 25 dis posed radially inwardly from the teeth 24. The combi* nation of the teeth 24 and the elongated apertures 25 define a wavy magnetic track on the follower wheel 23 and the track is magnetically coupled with the mag netic poles 22,22.

A balancing mass 26 is secured to the free end portion of the other central arm 6 and the balancing mass is suitably located to insure that the center of gravity of the vibrator lies along the center line L and is located in the plane of the vibrator.

One embodiment of an electric drive circuit is shown in FIG. 5 and the drive circuit comprises an electric power source El having its positive terminal connected to one side of the pickup-and-driving coil 18 and the negative terminal of the power source is connected to the emitters of transistors Trl and Tr2. The other end of the pickup-and-driving coil 18 is connected through a resistor R3 to the base ofthe transistor Trl. The positive terminal of the power source is also connected to the collector of the transistor Trl through a resistor R2.

The collector of the transistor Trl is connected to the base of the Tr2 through a capacitor C2.

An R-C biasing network comprising a capacitor C1 shunted by a resistor Rl is connected between the base and collector ofthe transistor Trl. A resistor R4 is coupled between the base and the collector of the transistor Tr2 and this resistor is provided to regulate the frequency ofthe drive circuit. As known in the art, the frequency of the drive circuit is adjusted to be a little lower than the natural frequency of the vibrator l. The circuit functions such that as the vibrator l vibrates, a voltage is induced in the pickup-and-driving coil causing the transistor Tr2 to turn on thereby delivering driving current to the coil 18 to drive the driving magnet.

Another embodiment of an electric drive circuit is shown in FIG. 6 and in this embodiment, the single pickup-and-driving coil 18 is separated into a driving coil 18a and a pickup coil 1811. An electric power source E2 has its positive terminal connected to the emitter of a transistor Tr3 and the negative terminal of the power source is connected to the collector of the transistor Tr3 through the driving coil [80. The base of the transistor Tr3 is connected to the negative terminal of the power source E2 through an R-C biasing network composed of a capacitor C3 which is shunted by a resistor R5 and the biasing network is in series with the pickup coil l8b which in turn is connected to the negative terminal of the power source. This drive circuit functions in a manner similar to that shown in FIG. 5 such that movement of the driving magnet past the pickup coil 18!) induces a voltage therein which is effective to turn on the transistor Tr3 causing current to flow through the driving coil 18b which in turn drives the magnet back through a return stroke The mode of operation of the vibratory system will now be described with reference to FIGS. 7A and 78. Referring first to FIG. 7A, as the pair of main vibratory arms 2 and 3 resiliently bend or flex upward, the free end of the vibrator moves leftward a small distance a and at the same time, the central vibratory arm 5 bends upward causing the free end thereof to move rightward. The leftward movement of the free end of the vibrator is the result of the small degree of pivotal movement of the vibrator about the supporting arms 7 and 8 whereas the rightward movement of the free end of the central vibratory arm 5 is due to the small degree of pivotal movement it undergoes about its pivotal point which is located at the connecting end portion 3 of the vibrator. It will be appreciated that the two displacements of the free end of the vibrator and the free end of the central arm 5 almost cancel each other out and therefore the driving magnet 14 and the driven magnet 20 move basically linearly in an upward direction in one sense along the center line L. At the same time, the other central vibratory arm 6 flexes downward in the opposite sense and this condition is shown in FIG. 7A which depicts the position of the various elements at the end of one vibratory stroke.

FIG. 7B depicts the position of the same elements at the end of the other vibratory stroke wherein the vibratory arms 2 and 3 are resiliently flexed downward causing the free end of the vibrator 1 to move leftward a small distance a. At the same time, the central vibratory arm 5 bends downward and its free end moves rightward almost the same distance. The two displacements cancel each other out as aforementioned to ef fect substantially linear downward movement of both the driving magnet 14 and the driven magnet 20 along the center line L. At this time, the other central vibratory arm 6 is flexed upward.

It should be noted that in order to ensure that the relative displacements of the free end of the vibrator 1 and the free end of the central vibratory arm 5 effectively cancel each other, the dimensions of the vibrator itself as well as the dimensions and configurations of the driving and driven magnets and the balancing mass 26 are designed to effectuate this purpose. In addition, the adjusting screw 16 is carefully adjusted to obtain a fine adjustment of the balance of the vibrator thereby ensuring that the driving magnet 14 reciprocates along a linear axis defined by the center line L. By such a construction, the gap spacing between the coil 18 and the magnet 14 may be reduced to a minimum value since clearance need not be provided to accommodate the angular movement of the driving magnet which has heretofore been necessary in the prior art devices.

A vibrator and vibratory system actually constructed in accordance with the principles of the invention has been used and the various vibrational modes are shown in FIG. 8. The normal vibrational mode A, was l28 Hz and the various vibratory arms vibrated in the manner shown. One spurious vibration mode A had a frequency of 85 Hz and another spurious vibration mode 1;, had a frequency of 173 Hz and the vibrational pattern of the vibratory arms was as shown in the drawing. From such an example, it may be readily seen that the frequency of the vibrator when operating in the normal vibration mode A, may be fully segregated from the frequencies of the spurious vibration modes A and A thereby ensuring that the vibrator vibrates in the normal vibrational mode. When vibrating in the normal vibrational mode, the quality factor Q of the vibrator was 2,000.

Another embodiment of the vibratory system is shown in FIGS. 9-11 and in this embodiment, the parts similar to those shown and described with reference to the embodiment of FIGS. 2-4 have corresponding reference numerals except that they are increased by 100. In this embodiment, the driven magnet 120 is mounted upon the central vibratory arm 106 by means of a supporting member 127 and the driving magnet 114 is mounted upon the central vibratory arm 105. It will be remembered that in the other embodiment, both the driving and driven magnets were secured to the same central arm whereas in this embodiment, the respective magnets are mounted on different ones of the central vibratory arms.

As seen in FIGS. 10 and 11, the supporting member 127 has two brackets 128,128 extending in parallel and each connected together at one of their end portions to form another supporting member 129. An adjusting screw 130 is threaded into the supporting member 129 and is used to regulate the balance of the vibrator. In this embodiment, the dimensions and configurations of the various parts are so constructed such that the center of gravity of the moving parts lies along a linear center line as in the former embodiment.

Thus it may be appreciated that according to the present invention, the driving magnet moves essentially linearly thereby making it possible to reduce the air gap between the driving magnet and the coil to a minimum value. Moreover, the normal vibrational mode varies very little even if the orientation of the vibrator is varied and this is due to the fact that the center of gravity of the moving parts moves in essentially a linear manner and is not influenced by the attitude ofthe vibrator. Furthermore, since the main vibratory arms 2,2 and one central vibratory arm bend in opposite directions, the vibrational energy cancels out at the supporting arms so that very little leakage of the vibrational energy occurs at the point of fastening. In addition, the linear movement of the driving magnet causes a very stable corresponding movement of the driven magnet and hence the follower wheel is accurately rotated.

The vibrator and vibratory system of the invention is especially suitable for use as a precision frequency source for a timepiece or the like and though obvious modifications and changes will become apparent to those skilled in the art, the present invention is intended to cover all such obvious modifications and changes which fall within the spirit and scope of the invention as defined in the appended claims.

What 1 claim is:

1. A mechanical vibrator for a timepiece or the like comprising: a vibratory unit composed of resilient sheet material and having two main vibratory arms disposed in spacedapart generally parallel relationship, two connecting end portions each interconnecting adjacent ends of said two main vibratory arms, and two central vibratory arms connected to respective ones of said connecting end portions and extending inwardly towards each other, and configured to vibrate, when supported at one said connecting end portion and suitably energized, in a normal vibrational mode wherein said two main vibratory arms along with the one central vibratory arm which is located remote from said one con necting end portion all flexurally vibrate in the same sense about their respective ends of connection while the other central vibratory arm which is connected to said one connecting end portion flexurally vibrates in the opposite sense about its end of connection such that the free end of said one central vibratory arm undergoes substantial linear vibratory movement; and means including a magnet secured to the free end of said one central vibratory arm for energizing said vibra tory unit in its normal vibrational mode.

2. A mechanical vibrator according to claim 1; wherein said magnet is secured to said free end of said one central vibratory arm at a location other than midway along the length of said two main vibratory arms.

3. A mechanical vibrator according to claim 1; wherein the center of gravity of said vibratory unit is situated in the region of said free end of said one central vibratory arm.

4. A mechanical vibrator according to claim 1; wherein the center of gravity of said vibratory unit is located in the region of the free end of one of said central vibratory arms.

5. A vibratory system comprising: a mechanical vibrator composed of resilient sheet material and having two main vibratory arms disposed in spaced-apart generally parallel relationship, two connecting end portions each interconnecting adjacent ends of said two main vibratory arms, and two central vibratory arms connected to respective ones of said connecting end portions and extending inwardly towards each other; supporting means connected to one of said connecting end portions for supporting said mechanical vibrator at said one connecting end portion to enable same to vibrate thereabout; a driving magnet secured to a free end of one of said central vibratory arms; means coacting with said mechanical vibrator and magnetically coupled with said driving magnet for magnetically driv ing said magnet to effect vibration of said mechanical vibrator in a normal vibrational mode wherein said free end of said one central vibratory arm alternately flexes about its corresponding connecting end portion accompanied by alternate flexing of said two main vibratory arms about said one connecting end portion such that said driving magnet alternately moves along a substantially linear path of travel; a rotatable output member; and means responsive to vibration of said mechanical vibrator for rotationally driving said output member in an intermittent manner.

6. A vibratory system according to claim wherein said mechanical vibrator is dimensioned and configured to ensure that transverse movement of said driving magnet, relative to its said path of travel, caused by flexing of said one central vibratory arm effectively cancels out that caused by flexing of said two main vibratory arms so that driving magnet undergoes substantially linear alternating movement.

7. A vibratory system according to claim 6; wherein said means for magnetically driving said magnet includes an energizeable coil having a hollow space in the center thereof which is disposed along said path of travel of said driving magnet and dimensioned to receive therein with a minimum clearance therebetween said driving magnet during linear alternating movement thereof along said path of travel.

8. A vibratory system according to claim 6; wherein said means responsive to vibration of said mechanical vibrator includes a driven magnet secured to the free end of said one central vibratory arm on the opposite side thereof from said driving magnet and vibrationally driven by said one central vibratory arm during vibration of said mechanical vibrator.

9. A vibratory system according to claim 6', wherein said means responsive to vibration of said mechanical vibrator includes a driven magnet secured to the free end of the other of said central vibratory arms and vibrationally driven thereby during vibration of said mechanical vibrator.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3360704 *Apr 22, 1965Dec 26, 1967Walter KohlhagenSpring-type electromechanical oscillator
US3448304 *Oct 7, 1966Jun 3, 1969Portescap Le PorteVibrator device
US3491257 *May 10, 1968Jan 20, 1970Centre Electron HorlogerResonance motor for portable timekeepers
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4793199 *Dec 15, 1986Dec 27, 1988Messerschmitt-Bolkow-Blohm GmbhElectromagnetic precision rotary drive
Classifications
U.S. Classification310/21, 310/25, 968/496, 310/22, 968/481, 368/160, 968/483
International ClassificationG04B15/00, H03H9/00, G04C5/00, H02K7/06, H02K7/065, H02K33/10, H02K33/00, H02K33/02, G04C3/00, G04C3/10, H03H9/24
Cooperative ClassificationG04C3/102, G04C3/10, H02K7/065, H02K33/02, G04C5/00, H02K33/10, H03H9/24
European ClassificationG04C3/10, H03H9/24, G04C5/00, H02K33/10, H02K33/02, H02K7/065, G04C3/10B2