TIMEPIECE REGULATING MECHANISM
United States Patent 3736743
In a timepiece driven by a vibrator, a spring having a spring constant much lower than that of the vibrator is coupled to the vibrator. The effective length of the spring is adjustable by varying the point of contact between a regulating mechanism and the spring. Adjustment of the vibration frequency can be effected from the exterior of the timepiece and can be carried out step-wise.
US Patent References:
REGULATOR ADJUSTING DEVICE FOR WATCH
Saito et al. - November 1970 - 3540210
REGULATOR OF TIMEPIECE
Tamaru - February 1969 - 3429119
Watches and like horological instruments
Heimann - November 1958 - 2858664
Timepiece regulator
Haefliger - December 1931 - 1835391
Escapement regulator
McKie et al. - September 1958 - 2852909
REGULATOR ADJUSTING DEVICE FOR WATCH
Saito et al. - November 1970 - 3540210
REGULATOR OF TIMEPIECE
Tamaru - February 1969 - 3429119
Watches and like horological instruments
Heimann - November 1958 - 2858664
Timepiece regulator
Haefliger - December 1931 - 1835391
Escapement regulator
McKie et al. - September 1958 - 2852909
Application Number:
05/180040
Publication Date:
06/05/1973
Filing Date:
09/13/1971
View Patent Images:
Export Citation:
Assignee:
Kabushiki Kaisha Suwa Seikosha (Tokyo, JA)
Primary Class:
Other Classes:
968/108, 968/486, 968/114, 368/168
International Classes:
G04B17/04; G04B18/00; G04C3/10; G04B17/00; G04C3/00; G04B17/14
Field of Search:
58/23TF,116R,116M,109,113
US Patent References:
Primary Examiner:
Wilkinson, Richard B.
Assistant Examiner:
Wal, Stanley A.
Claims:
What is claimed is
1. In an electrically-powered timepiece wherein a tuning fork having a spring constant k provides the frequency on which the timepiece rate is based, a frequency regulating mechanism, comprising a spring one end of which is coupled to said tuning fork and having a spring constant Δk small relative to k, the effective length of said spring being adjustable over a range such that the vibration frequency of said tuning fork is variable over a desired range, and means for adjusting the effective length of said spring.
2. The frequency regulating mechanism as defined in claim 1, further comprising a rod slidably mounted in said timepiece and a pawl and ratchet combination operatively connecting said rod and said spring so that an inward and an outward excursion of said rod causes a stepwise change in said effective length of said spring and thereby causes a stepwise change in said vibration frequency.
3. The frequency regulating mechanism as defined in claim 2, wherein said rod is mounted for rotation through a fixed but limited angle to either of two extreme positions, said rod in one extreme position being disposed to increase said vibration frequency and in the other extreme position being disposed to decrease said vibration frequency, said changes in frequency being effected by an inward and outward excursion of said rod.
4. The frequency regulating mechanism as defined in claim 2, wherein said rod protrudes through the exterior of said timepiece and is actuatable from the exterior of said timepiece.
5. A frequency regulating mechanism as defined in claim 1, wherein said adjusting means comprises a member adjacent said spring and movable to make contact with said spring at any desired point thereof, thereby determining the effective length of said spring.
6. The frequency regulating mechanism as defined in claim 2, wherein said spring is essentially circular and said member comprises a central shaft, an arm rotatably mounted on said shaft and a pin mounted on said arm at a radial distance such that it makes contact with said essentially circular spring.
7. The frequency regulating mechanism as defined in claim 3, wherein said adjusting member further comprises a first gear mounted on said shaft, a second gear engaging said first gear and means for rotating said second gear, thereby rotating said first gear and adjusting the point of contact between said pin and said spring.
8. The frequency regulating mechanism as defined in claim 7, wherein said first and second gears are a worm gear and worm combination.
9. The frequency regulating mechanism as defined in claim 7, wherein said first and second gears are a crown gear and spur gear combination, the shape of said crown gear being such as to compensate for any non-linearity in the effect of said effective length of said spring on said vibration frequency so that the change in vibration frequency occasioned by rotation of said second gear is proportional to the angle through which said second gear is rotated.
10. The frequency regulating mechanism as defined in claim 7, wherein said second gear is rotatable by means exterior to said timepiece.
11. The frequency regulating mechanism as defined in claim 3, further comprising a second arm mounted rotatably on said shaft, said second arm having proximate the end thereon a collet in which that end of said spring not attached to said vibration means is slidably mounted, thereby making it possible to adjust the curvature of said spring.
12. The frequency regulating mechanism as defined in claim 3, wherein said mechanism comprises a base plate and a collet fixed to said base plate, the end of said spring not attached to said vibration means being slidably mounted in said collet thereby providing for adjustment of the curvature of said spring.
13. In an electrically-powered timepiece wherein a mechanical vibration means other than a balance-wheel escapement and main-spring combination provides the frequency on which the timepiece rate is based, said mechanical vibration means having a spring constant k, a frequency regulating mechanism, comprising a spring one end of which is coupled to said vibration means and having a spring constant Δk small relative to k, the effective length of said spring being adjustable over a range such that the vibration frequency of said vibration means is variable over a desired range, and means for adjusting the effective length of said spring.
14. A frequency regulating mechanism as defined in claim 13 where said spring is directly and permanently coupled at one end of said effective length thereof to said vibration means.
1. In an electrically-powered timepiece wherein a tuning fork having a spring constant k provides the frequency on which the timepiece rate is based, a frequency regulating mechanism, comprising a spring one end of which is coupled to said tuning fork and having a spring constant Δk small relative to k, the effective length of said spring being adjustable over a range such that the vibration frequency of said tuning fork is variable over a desired range, and means for adjusting the effective length of said spring.
2. The frequency regulating mechanism as defined in claim 1, further comprising a rod slidably mounted in said timepiece and a pawl and ratchet combination operatively connecting said rod and said spring so that an inward and an outward excursion of said rod causes a stepwise change in said effective length of said spring and thereby causes a stepwise change in said vibration frequency.
3. The frequency regulating mechanism as defined in claim 2, wherein said rod is mounted for rotation through a fixed but limited angle to either of two extreme positions, said rod in one extreme position being disposed to increase said vibration frequency and in the other extreme position being disposed to decrease said vibration frequency, said changes in frequency being effected by an inward and outward excursion of said rod.
4. The frequency regulating mechanism as defined in claim 2, wherein said rod protrudes through the exterior of said timepiece and is actuatable from the exterior of said timepiece.
5. A frequency regulating mechanism as defined in claim 1, wherein said adjusting means comprises a member adjacent said spring and movable to make contact with said spring at any desired point thereof, thereby determining the effective length of said spring.
6. The frequency regulating mechanism as defined in claim 2, wherein said spring is essentially circular and said member comprises a central shaft, an arm rotatably mounted on said shaft and a pin mounted on said arm at a radial distance such that it makes contact with said essentially circular spring.
7. The frequency regulating mechanism as defined in claim 3, wherein said adjusting member further comprises a first gear mounted on said shaft, a second gear engaging said first gear and means for rotating said second gear, thereby rotating said first gear and adjusting the point of contact between said pin and said spring.
8. The frequency regulating mechanism as defined in claim 7, wherein said first and second gears are a worm gear and worm combination.
9. The frequency regulating mechanism as defined in claim 7, wherein said first and second gears are a crown gear and spur gear combination, the shape of said crown gear being such as to compensate for any non-linearity in the effect of said effective length of said spring on said vibration frequency so that the change in vibration frequency occasioned by rotation of said second gear is proportional to the angle through which said second gear is rotated.
10. The frequency regulating mechanism as defined in claim 7, wherein said second gear is rotatable by means exterior to said timepiece.
11. The frequency regulating mechanism as defined in claim 3, further comprising a second arm mounted rotatably on said shaft, said second arm having proximate the end thereon a collet in which that end of said spring not attached to said vibration means is slidably mounted, thereby making it possible to adjust the curvature of said spring.
12. The frequency regulating mechanism as defined in claim 3, wherein said mechanism comprises a base plate and a collet fixed to said base plate, the end of said spring not attached to said vibration means being slidably mounted in said collet thereby providing for adjustment of the curvature of said spring.
13. In an electrically-powered timepiece wherein a mechanical vibration means other than a balance-wheel escapement and main-spring combination provides the frequency on which the timepiece rate is based, said mechanical vibration means having a spring constant k, a frequency regulating mechanism, comprising a spring one end of which is coupled to said vibration means and having a spring constant Δk small relative to k, the effective length of said spring being adjustable over a range such that the vibration frequency of said vibration means is variable over a desired range, and means for adjusting the effective length of said spring.
14. A frequency regulating mechanism as defined in claim 13 where said spring is directly and permanently coupled at one end of said effective length thereof to said vibration means.
Description:
BACKGROUND OF THE INVENTION
In conventional frequency regulating devices for watches driven by means of a vibrator, it has generally been necessary to open the watch case in order to regulate the rate of vibration of the vibrator. The opening and closing of a watch or other timepieces for this purpose is time consuming and results in the entry of dust to the inside of the timepiece.
Although regulator adjusting means operable from the exterior of a timepiece where the timepiece is driven by a tuning fork are known, it has been found to be difficult to adjust the frequency with sufficient precision. In such conventional devices, the permanent magnet used in combination with the tuning fork is connected to a screw projecting through the case of the timepiece. Such a mechanism is not suitable for carrying out adjustments in a step-wise mode. Also, it is difficult to provide that the change in frequency of the vibrating means shall be proportional to the angle through which the adjusting screw is rotated.
SUMMARY OF THE INVENTION
Where a timepiece is driven by mechanical vibration means such as a tuning fork, said vibration means having a spring constant k, a suitable frequency regulating mechanism comprises a spring, one end of which is coupled to said vibration means, said spring having a spring constant Δ k small relative to k, the effective length of said spring being adjustable over a range such that the vibration frequency of said vibration means is variable over a desired range, and means for adjusting the effective length of said spring.
The spring is conveniently circular and is centered with respect to a shaft on which is rotatably mounted an arm bearing a pin. The pin engages the spring and rotation of the arm changes the point of engagement, thereby changing the effective length of the spring. The arm can be rotated about the shaft by means of a pawl and ratchet wheel arrangement actuatable by a push rod protruding through the case of the timepiece. This operating method provides for step-wise adjustment of the vibration frequency. The arm can also be rotated by gear sets which yield a frequency change which is a linear function of the angle through which an adjusting screw is turned. The adjusting screw can also be made operable from the exterior of the timepiece.
Accordingly, it is an object of the present invention to provide a means of precisely adjusting a timepiece driven by a vibrator.
Another object of the present invention is to provide a means of regulating a timepiece driven by a vibrator where the regulation is carried out step-wise.
A further object of the invention is to provide a means of regulating a timepiece driven by a vibrator where the regulation is effected from the exterior of the timepiece.
Yet another object of the invention is a means of regulating a timepiece driven by a vibrator where the change in frequency resulting from rotation of an adjusting screw is proportional to the angle through which said screw is rotated.
A still further object of the invention is a means of regulating a timepiece driven by a vibrator where an adjusting means is coupled to an arm of a tuning fork.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.
BRIEF DESCRIPTION OF THE DRAWING
For a fuller understanding of the invention, reference is had to the following description taken in connection with the accompanying drawing, in which:
FIG. 1 is a plan view of a frequency regulating mechanism in accordance with the present invention, coupled to a tuning fork;
FIG. 2 shows a mechanism similar to that of FIG. 1 in which the curvature of a hairspring can be varied;
FIG. 3 is an elevational view in partial cross-section of the regulating mechanism of FIG. 2;
FIG. 4 is a plan view of a frequency regulation mechanism mounted on the base of a tuning fork;
FIG. 5A is a plan view of a regulating mechanism operated by spur gears;
FIG. 5B is a sectional view taken along line 5B--5B of FIG. 5A;
FIG. 6 is a plan view of a regulating mechanism operated by a worm and worm gear combination;
FIG. 7 shows diagrammatically how the effective lengths of the spring varies with rotation of an arm;
FIG. 8 shows two functional relationships between the effective lengths of the spring and the vibration frequency of the vibration means;
FIG. 9 shows a crown gear and spur gear combination making it possible to compensate for non-linearity in the relationship between the effective length of the spring and the vibration frequency of the vibration means; and
FIG. 10 shows an embodiment of the frequency regulating mechanism in which the frequency can be adjusted step-wise.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A frequency regulating mechanism in accordance with the present invention is shown in FIG. 1 and generally indicated by the reference numeral 11 is coupled to a tuning fork 12 carrying weights 13 on the ends thereof. The regulating mechanism 11 is mounted on a shaft 14 and is held thereon by a spring loaded washer 15. The mechanism comprises a spring 16 one end of which is held in a collet 17 on a stud 18 mounted on an arm of the tuning fork 12. The other end of spring 16 is fixed in a stud 19 mounted on arm 21 which rotates about shaft 14. A second arm 22 which also rotates about shaft 14 carries a pin 23. Pin 23 makes contact with spring 16 thereby defining the effective length of the spring as that section between collet 14 and pin 23. The function of arm 21 is to establish the curvature of spring 16 as a circle slightly smaller than that followed by pin 23. In consequence, pin 23 makes firm but relatively frictionless contact with spring 16. Tuning fork 12 is mounted to a base-plate (not shown) by screws 24. The regulating mechanism 11 is mounted to the same base-plate.
Instead of fixing the adjustable end of spring 16 to a movable arm as is shown in FIG. 1, the adjustable end of spring 16 can be held in the slot of a collet 25 as shown in FIGS. 2 and 3. In this embodiment, arm 22 is held by wide-headed screw 26 to base-plate 27 with washer 28 between the head of screw 26 and base-plate 27. The curvature of spring 16 is adjusted by moving the outer end of spring 16 through the slot of screw 25.
It is also possible for the regulating mechanism to be mounted on the base of tuning fork 12 as shown in FIG. 4. Here, one end is fixed to the arm of tuning fork 12 by the collet 17. The other end of the spring 16 is held in collet 29 which is mounted on the base of the tuning fork 12.
Although the position of arm 22 may be varied manually, it is preferable that the arm be positioned from a location exterior to the regulating mechanism and more preferably from a location exterior to the timepiece. Such an arrangement is shown in FIGS. 5A and 5B wherein regulator arm 22 is joined to a sector gear 31 which is driven by spur gear 32. Spur gear 32 is rotated by a slotted shaft 32' which is external to the mechanism and which may extend through the case of the timepiece.
In another embodiment (FIG. 6), arm 22 is attached to worm gear 33 driven by worm 34. Worm 34 is turned by means of shaft 35 which protrudes through timepiece housing 36 in the form of a slotted head. Shaft 35 is held in bearings 38.
The formula governing the relationship between the spring constants of the vibrating means and the spring on the one hand and the equivalent mass of the vibrator is given by the following formula
f = 1/(2 π) √ (k + Δ k)/M
where, M is the equivalent mass of the vibrator, and Δk is the spring constant of the frequency regulating spring. The value of Δk is small relative to that of k; consequently it is possible to adjust the frequency of the vibrating means with great accuracy. Changes in the frequency of the vibrating means are generally due to processing such as the ageing of the materials of which the vibrating means is made.
The spring constant of the regulating spring is a function of the effective length of the spring, but, in general, the relationship is definitely non-linear. A typical relationship is shown in curve a of FIG. 8. The effective length of spring 16 is the portion between pin 23 on arm 22 and collet 17. This length is indicated as portion 39 in FIG. 7. Arm 22 is represented schematically in this Figure and is shown as being positioned at an angle alpha measured from the arm to the line joining the center of rotation and collet 17.
A means of compensating for the non-linearity between the vibration frequency and the angle through which arm 22 is rotated is shown in FIG. 9. In the embodiment shown in this Figure, arm 22 is joined with and rotates with crown gear 41 driven by spur 42. In this embodiment, crown gear 41 is circular but teeth 43 of crown gear 41 describe a circle having a center at 44. As is evident from FIG. 9, center 44 is displaced substantially from center of rotation 45 of arm 22. Curve b of FIG. 8 shows the relationship between the effective length of spring 16 and the frequency of vibration of the vibrating means. It is obvious that in this particular embodiment, the use of the crown gear with displaced center is effective in producing a linear function. Needless to say, crown gears with teeth lying on curves other than circles could also be used if necessary.
It should be noted that spur gear 42 can be rotated by slotted head 46 from outside the regulating mechanism or from outside of the timepiece. In the embodiment shown in FIG. 9, slotted head 46 protrudes through case 47.
In the embodiments described thus far, adjustment of the frequency regulating mechanism, where carried out from external to the mechanism itself, has involved the rotation of a shaft. However, it is also possible to adjust the regulating mechanism by a translational movement from the exterior of the timepiece. Such an arrangement is shown in FIG. 10 where regulating arm 22 is joined to sector gear 31 which is driven by spur gear 48. Spur gear 48 is a ratchet wheel which operates in combination with the two pawls 49 and 51 at the extremities of shoe 52. Shoe 52 has a slot 53 which receives pin 54. When at rest, shoe 52 is held away from ratchet 48 by spring 55. Pressure on knurled knob 56 forces foot 57 inwardly so that toe 58 makes contact with shoe 52. In the position shown in FIG. 10, pawl 49 makes contact with ratchet wheel 48 and rotates arm 22 in counter-clockwise direction. Crown 56 can be rotated through a limited angle to take either of two positions in one of which pawl 49 actuates ratchet wheel 48 and the other of which pawl 51 actuates ratchet wheel 48.
After actuation of the foot 57, release of crown 56 causes an outward movement of shoe 57 as the result of pressure from spring 59. A collar 60 limits the outward excursion of foot 57.
The mechanism of FIG. 10 has the advantage that a single inward and outward excursion of a foot results in a step-wise change in the position of pin 23 making contact with spring 16 and thereby causes a step-wise change in the effective length of spring 16. It then becomes possible to calibrate the change in vibration frequency resulting from each inward and outward excursion of foot 57. Although regulation is achieved by inward and outward excursion of foot 57, the direction of the resulting change in frequency depends on the orientation of foot 57. As stated above, the angle through which foot 57 can be rotated is limited. The most suitable angle is about 180°; to hold the rotation to this angle, a plate 62 is positioned adjacent foot 57. Rotation beyond the desired limits is achieved by positioning of a plate 62 adjacent foot 57. Plate 62 is essentially parallel to shoe 52. Rotation of foot 57 beyond the desired limiting positions is present by contact of toe 58 with plate 62.
It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.
In conventional frequency regulating devices for watches driven by means of a vibrator, it has generally been necessary to open the watch case in order to regulate the rate of vibration of the vibrator. The opening and closing of a watch or other timepieces for this purpose is time consuming and results in the entry of dust to the inside of the timepiece.
Although regulator adjusting means operable from the exterior of a timepiece where the timepiece is driven by a tuning fork are known, it has been found to be difficult to adjust the frequency with sufficient precision. In such conventional devices, the permanent magnet used in combination with the tuning fork is connected to a screw projecting through the case of the timepiece. Such a mechanism is not suitable for carrying out adjustments in a step-wise mode. Also, it is difficult to provide that the change in frequency of the vibrating means shall be proportional to the angle through which the adjusting screw is rotated.
SUMMARY OF THE INVENTION
Where a timepiece is driven by mechanical vibration means such as a tuning fork, said vibration means having a spring constant k, a suitable frequency regulating mechanism comprises a spring, one end of which is coupled to said vibration means, said spring having a spring constant Δ k small relative to k, the effective length of said spring being adjustable over a range such that the vibration frequency of said vibration means is variable over a desired range, and means for adjusting the effective length of said spring.
The spring is conveniently circular and is centered with respect to a shaft on which is rotatably mounted an arm bearing a pin. The pin engages the spring and rotation of the arm changes the point of engagement, thereby changing the effective length of the spring. The arm can be rotated about the shaft by means of a pawl and ratchet wheel arrangement actuatable by a push rod protruding through the case of the timepiece. This operating method provides for step-wise adjustment of the vibration frequency. The arm can also be rotated by gear sets which yield a frequency change which is a linear function of the angle through which an adjusting screw is turned. The adjusting screw can also be made operable from the exterior of the timepiece.
Accordingly, it is an object of the present invention to provide a means of precisely adjusting a timepiece driven by a vibrator.
Another object of the present invention is to provide a means of regulating a timepiece driven by a vibrator where the regulation is carried out step-wise.
A further object of the invention is to provide a means of regulating a timepiece driven by a vibrator where the regulation is effected from the exterior of the timepiece.
Yet another object of the invention is a means of regulating a timepiece driven by a vibrator where the change in frequency resulting from rotation of an adjusting screw is proportional to the angle through which said screw is rotated.
A still further object of the invention is a means of regulating a timepiece driven by a vibrator where an adjusting means is coupled to an arm of a tuning fork.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.
BRIEF DESCRIPTION OF THE DRAWING
For a fuller understanding of the invention, reference is had to the following description taken in connection with the accompanying drawing, in which:
FIG. 1 is a plan view of a frequency regulating mechanism in accordance with the present invention, coupled to a tuning fork;
FIG. 2 shows a mechanism similar to that of FIG. 1 in which the curvature of a hairspring can be varied;
FIG. 3 is an elevational view in partial cross-section of the regulating mechanism of FIG. 2;
FIG. 4 is a plan view of a frequency regulation mechanism mounted on the base of a tuning fork;
FIG. 5A is a plan view of a regulating mechanism operated by spur gears;
FIG. 5B is a sectional view taken along line 5B--5B of FIG. 5A;
FIG. 6 is a plan view of a regulating mechanism operated by a worm and worm gear combination;
FIG. 7 shows diagrammatically how the effective lengths of the spring varies with rotation of an arm;
FIG. 8 shows two functional relationships between the effective lengths of the spring and the vibration frequency of the vibration means;
FIG. 9 shows a crown gear and spur gear combination making it possible to compensate for non-linearity in the relationship between the effective length of the spring and the vibration frequency of the vibration means; and
FIG. 10 shows an embodiment of the frequency regulating mechanism in which the frequency can be adjusted step-wise.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A frequency regulating mechanism in accordance with the present invention is shown in FIG. 1 and generally indicated by the reference numeral 11 is coupled to a tuning fork 12 carrying weights 13 on the ends thereof. The regulating mechanism 11 is mounted on a shaft 14 and is held thereon by a spring loaded washer 15. The mechanism comprises a spring 16 one end of which is held in a collet 17 on a stud 18 mounted on an arm of the tuning fork 12. The other end of spring 16 is fixed in a stud 19 mounted on arm 21 which rotates about shaft 14. A second arm 22 which also rotates about shaft 14 carries a pin 23. Pin 23 makes contact with spring 16 thereby defining the effective length of the spring as that section between collet 14 and pin 23. The function of arm 21 is to establish the curvature of spring 16 as a circle slightly smaller than that followed by pin 23. In consequence, pin 23 makes firm but relatively frictionless contact with spring 16. Tuning fork 12 is mounted to a base-plate (not shown) by screws 24. The regulating mechanism 11 is mounted to the same base-plate.
Instead of fixing the adjustable end of spring 16 to a movable arm as is shown in FIG. 1, the adjustable end of spring 16 can be held in the slot of a collet 25 as shown in FIGS. 2 and 3. In this embodiment, arm 22 is held by wide-headed screw 26 to base-plate 27 with washer 28 between the head of screw 26 and base-plate 27. The curvature of spring 16 is adjusted by moving the outer end of spring 16 through the slot of screw 25.
It is also possible for the regulating mechanism to be mounted on the base of tuning fork 12 as shown in FIG. 4. Here, one end is fixed to the arm of tuning fork 12 by the collet 17. The other end of the spring 16 is held in collet 29 which is mounted on the base of the tuning fork 12.
Although the position of arm 22 may be varied manually, it is preferable that the arm be positioned from a location exterior to the regulating mechanism and more preferably from a location exterior to the timepiece. Such an arrangement is shown in FIGS. 5A and 5B wherein regulator arm 22 is joined to a sector gear 31 which is driven by spur gear 32. Spur gear 32 is rotated by a slotted shaft 32' which is external to the mechanism and which may extend through the case of the timepiece.
In another embodiment (FIG. 6), arm 22 is attached to worm gear 33 driven by worm 34. Worm 34 is turned by means of shaft 35 which protrudes through timepiece housing 36 in the form of a slotted head. Shaft 35 is held in bearings 38.
The formula governing the relationship between the spring constants of the vibrating means and the spring on the one hand and the equivalent mass of the vibrator is given by the following formula
f = 1/(2 π) √ (k + Δ k)/M
where, M is the equivalent mass of the vibrator, and Δk is the spring constant of the frequency regulating spring. The value of Δk is small relative to that of k; consequently it is possible to adjust the frequency of the vibrating means with great accuracy. Changes in the frequency of the vibrating means are generally due to processing such as the ageing of the materials of which the vibrating means is made.
The spring constant of the regulating spring is a function of the effective length of the spring, but, in general, the relationship is definitely non-linear. A typical relationship is shown in curve a of FIG. 8. The effective length of spring 16 is the portion between pin 23 on arm 22 and collet 17. This length is indicated as portion 39 in FIG. 7. Arm 22 is represented schematically in this Figure and is shown as being positioned at an angle alpha measured from the arm to the line joining the center of rotation and collet 17.
A means of compensating for the non-linearity between the vibration frequency and the angle through which arm 22 is rotated is shown in FIG. 9. In the embodiment shown in this Figure, arm 22 is joined with and rotates with crown gear 41 driven by spur 42. In this embodiment, crown gear 41 is circular but teeth 43 of crown gear 41 describe a circle having a center at 44. As is evident from FIG. 9, center 44 is displaced substantially from center of rotation 45 of arm 22. Curve b of FIG. 8 shows the relationship between the effective length of spring 16 and the frequency of vibration of the vibrating means. It is obvious that in this particular embodiment, the use of the crown gear with displaced center is effective in producing a linear function. Needless to say, crown gears with teeth lying on curves other than circles could also be used if necessary.
It should be noted that spur gear 42 can be rotated by slotted head 46 from outside the regulating mechanism or from outside of the timepiece. In the embodiment shown in FIG. 9, slotted head 46 protrudes through case 47.
In the embodiments described thus far, adjustment of the frequency regulating mechanism, where carried out from external to the mechanism itself, has involved the rotation of a shaft. However, it is also possible to adjust the regulating mechanism by a translational movement from the exterior of the timepiece. Such an arrangement is shown in FIG. 10 where regulating arm 22 is joined to sector gear 31 which is driven by spur gear 48. Spur gear 48 is a ratchet wheel which operates in combination with the two pawls 49 and 51 at the extremities of shoe 52. Shoe 52 has a slot 53 which receives pin 54. When at rest, shoe 52 is held away from ratchet 48 by spring 55. Pressure on knurled knob 56 forces foot 57 inwardly so that toe 58 makes contact with shoe 52. In the position shown in FIG. 10, pawl 49 makes contact with ratchet wheel 48 and rotates arm 22 in counter-clockwise direction. Crown 56 can be rotated through a limited angle to take either of two positions in one of which pawl 49 actuates ratchet wheel 48 and the other of which pawl 51 actuates ratchet wheel 48.
After actuation of the foot 57, release of crown 56 causes an outward movement of shoe 57 as the result of pressure from spring 59. A collar 60 limits the outward excursion of foot 57.
The mechanism of FIG. 10 has the advantage that a single inward and outward excursion of a foot results in a step-wise change in the position of pin 23 making contact with spring 16 and thereby causes a step-wise change in the effective length of spring 16. It then becomes possible to calibrate the change in vibration frequency resulting from each inward and outward excursion of foot 57. Although regulation is achieved by inward and outward excursion of foot 57, the direction of the resulting change in frequency depends on the orientation of foot 57. As stated above, the angle through which foot 57 can be rotated is limited. The most suitable angle is about 180°; to hold the rotation to this angle, a plate 62 is positioned adjacent foot 57. Rotation beyond the desired limits is achieved by positioning of a plate 62 adjacent foot 57. Plate 62 is essentially parallel to shoe 52. Rotation of foot 57 beyond the desired limiting positions is present by contact of toe 58 with plate 62.
It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.