US2330416A - Timing apparatus for clocks and watches - Google Patents

Description

Sept. 28, i943, T. B. GIBBs C l TIMING AFPARATUS FOR CLOCKS AND WATCHES Filed Feb. 1o, l1940 Patented Sept.V 28, 1943 TINHNG APPARATUS FOR CLOCKS AND WATCHES i Thomas B. Gibbs, Chicago, Ill., assigner 'to George W. Borg Corporation, Chicago', Ill., a corporation of Delaware Application February 1o, 1940, seriarNo. 318382 L 17 Claims.

The present invention relates in general to timing apparatus for clocks and watches, and

more in particular to an arrangement of appara- .tus for timing the balance-wheel of a clock or watch before it is assembled with the remainder of the movement. It is the common practicegin the art to time balance-wheels by adjusting the length of the associated hairsprings and the operation of timing is therefore commonly referred7 to as hairspring vibrating. The object of the invention is the production' of new and improved apparatus for vibratingl hairsprings.

'I'he invention will bedescribed more in detail hereinafter with reference to the accompanying drawing, in which Fig. 1 shows diagrammatically the circuits and apparatus involved, while Fig. 2 shows the character of record that may be obtained on the recording device that forms part of the apparatus.

Referring to Fig. 1, the equipment therein shown will be briefly described. The reference character 2 indicates a balance-wheel having a hairspring 3, whichis to be timed or vibrated as mentioned in the foregoing. The balancewheel is supported on a suitable stand (not shown) having pivots for the balance staff so arranged that the balance-wheel can be quickly placed in position and removed. The end of the hairspring 3 is clamped between the two rollers 4 and 5, one of which may be provided with a knob by which it can be rotated to feed the hairsprng in and out to adjust the effective length thereof. The details of a suitable stand for the purpose are well known in the art.

The reference character 6 indicates a source of light which is arranged in any suitable manner, as by a reflector or lens system, to throw a beam of light onto the rim of the balance-wheel 2. IThe reflected beam is intercepted by a photocellv 1. The cathode of the photocell is grounded, while the anode is connected to the plus B lead I2 through resistors 8 and 9. A lter condenser of a condenser I5 to the control grid of a second:4

space discharge tube I6, which may be the same as tube I3 and also has a conventional amplifier 55 circuit.

- This tube may be of the triode type, and is cou- A third space discharge tube is indicated at I l.

pled to the preceding stage through a condenser I6. The grid circuit in the case of tube I1 preferably includes the variable resistance I9 which may be used to regulate the potentials impressed on the grid by the preceding,l stage. The plate circuit includes the primary winding 20 of the transformer 2|.

The reference character 23 indicates a rectier tube which is connected in series with the secondary winding 22 of transformer 2I and the resistance 24. A direct current voltmeter 21 is arranged to measure the drop across the re tubes, also negative potential for biasing the grid of tube 28. The filament or heater circuits of the tubes are conventional and-have been omittedin order to simplify the drawing.

AThe apparatus includes `means for directing spurts or impulses of air against the rim of the balance-wheel in order to start and maintain the periodic oscillations thereof. The air impulses are delivered at a constant rate or frequency which is the current frequency for the wheel. This part of the apparatus will now be described briefly.

When the balance-Wheel 2 is positioned on the stand ready to be vibrated or regulated, the rim of the balance-wheel is a short distance above a shield or plate 32, which may form part of the stand, and which is provided with small openings 33 and 36. These openings are in the plane of the balance wheel and are equally spaced on opposite sides of the balance` staff. Beneath the plate 32 there is arranged an air pipe 35, the lower end of which has a pivotal connection with the junction box 36. The pipe 35 is in the same vertical plane with' the openings 33 and 34. Air

is supplied to box 36 and pipe 35 through a vaive 3l and pipe 33, the latter being connected to any suitable pump and reservoir system for furnishing compressed, air at constant pressure. It will be seen that'if the pipe 36 is given the properr reciprocating motion about its pivot the upper.

printer is in operation, although the feed mechanism for the paper strip 53 may be stopped for the time being. Disc 5| is rotating, likewise gears 60 and 5|', and the air pipe 35 is movingto and fro between openings- 33 and 34. The air valve 31 should be adjusted properly so that a stream of air of the requisite velocity ywillbe issuing from vice, sometimes referred to as afprinter, may

be of the type shown and described in the patent to Gibbs, No. 2,254,649, granted September 2, 1941. The essential parts of the recording device are shown diagrammatically in' the drawing and will be^described briefly. l

The shaft 5|) is driven at constant speed by any suitable means such as a synchronous motor which is supplied with current of constant frequency. On the'shaft 50 there is mounted a toothed disc 5|, which rotates `beneath a strip of paper or other record material 53. Suitable i means is provided for feeding-the paper strip p'ast the edge of the disc in a direction parallel to its rotation axis and for giving the strip a curved formation where-it passes the disc. 'Ihe feeding means is preferably arranged so that it can be started and stopped independent of rotation of the disc 5|. The reference character 54 indicates a printing ribbon which extends transversely across the strip 53 in the plane of disc 5|. The ribbon may be fed along in known manner. Above the ribbon is located the printer bar 55, which is arranged to be operated by the electromagnets 55 and 51. When the magnets are energized momentarily the printer bar is pulled down and presses the ribbon and paper strip momentarily against some tooth of the) disc 5| which at the moment is passing beneath the strip. This operation'prints a short dash or mark on the strip. The energization of the electromagnets 56 and 51 is 'controlled by the tube 23 in a manner which will be explained shortly.

As previously intimated,`the printer is arranged to operate the air pipe 35 and to this end is Dro-v vided with a gear wheel B which is supported on the shaft and rotates with it. Suitably sulported onthe frame of the printer there is a second gear wheel 6| .which is in mesh with gear 60. Gear 3| has an annular flange B2 at one side thereof on which is fixed a pivot stud 5.3. The latter supports one end of a connecting rod which comprises the members 64 and 55, the threaded rod 31 and the bracket 68 attached to pipe 35. It

' the end of pipe 35. l. A balance-wheel such as 2 may now be placed in position on the stand, with the end of the hairspring clamped between the rollers 4 and 5. g Being free to oscillate in its bearings, the balancegranted February 11, 1941.

will be seen that when the gear 6| is rotated the air pipe 35 will be moved back and yforth on its pivot. The parts are soadjusted that with gear 5| in the position in which itis shown the pipe 35 will be exactly underneath the opening 33, while if the gear 8| is rotated 180 degrees the pipe will moveto a position in which it is exactly underneath the opening 34.

The speed at which the shaft is driven de- 'pends on the correct beat frequency of the bal- 'wheel, may-now be described. For this purpose,

it may be assumed that the recording device or wheel will immediately be set in motion by the blasts of air which issue alternately from openings 33 and 34 and impinge on the rim of the wheel ilrst to one side and then to the other. .Assuming that. kthe hairspring is clamped at approximately the correct point, as determined by experience, the balance-'wheel will rapidly pick up motion and will begin to oscillate with appreciable amplitude."

When the balance-wheel is set in motion as described in the preceding paragraph, certain variations are producedy in the current which flows through .the-photocell. The photocell current is responsive to light reflected from the rim of the wheel and the variations are due to movement of the wheel beneath the impinging light beam. This phenomenon is more fully described in the patent to Gibbs and Brown, No. 2,231,849, It will be sufficient to state here that the crrents generated by the photocell due to movement of thebalance-wheel are of various frequencies, including components having a much hlgherfrequency than the frequency of the wheel, andthat the volume increases with the amplitude of the wheel, that is, with the speed` at which the rim of the wheel moves beneath the impinging light beam. The currents are generated while the wheel is in motion in either direction and cease when the wheel stops to reverse its direction of rotation.

mining when the balance-wheel is properly regulated. One of these is the voltmeter 21, which provides for a coarse regulation, sufficient for some purposes. The other is the recording device, by means ofwhich a finer adjustment can be secured if desired. The process of vibrating or regulating by use of the voltmeter will rst be explained.

'Ihe photo lcell currents generated by movement of the balance-Wheel are amplified in the tube I3, and are further amplied in tubes I6 and I1, with the result that considerable variations in the plate current at tube |1 take place, whereby alternating voltages are induced in the'secohdary winding 22 of transformer 2|. An intermittent direct current therefore flows in the circuit which includes the secondary winding 22, the rectifier tube 23, and the resistance 24. The value'of this current is proportional izo-the amplitude of the balance-wheel oscillations, and is measured by the voltmeter 21; or rather, ythe voltmeter 21 measures the drop across the resistance 24, which is proportional to the current flow. The filter arrangement comprising the resistance 25 and condenser 26 enables the voltmeter to show a steady reading.

l The method of hairspring vibration or regulaytion according to the invention depends on the fact that the balance-wheel will attain amaxi.V

mum amplitude when its natural frequency of oscillation is the same as the frequency of the air blasts by which it is driven. If the frequency asaanc f of the wheel is different from the air blast frequency the wheel will oscillate with an amplitude which is less than its maximum and willfall out of step with the air blasts at regular intervals the length of which is inversely proportional f'to the difference in frequency.

In practice the hairsprings are always made too long, for obvious reasons, and the natural frequency of the balance-wheel 2 will therefore be too low when the vibrating operation is started. The operator is, of course, acquainted with the situation and understands that she has to raise.

the balance-wheel frequency until it is the same as the air blast frequency. This is done by rotating the roller 5 in the proper direction to feed the hairspring to the left and thus shorten its effective length, the voltmeter 21 being observed at the same time to note the effect on the amplitude of the wheel. As the hairspring is shortened the balance-wheel will run in step with the air blasts for increasingly long periods and its amplitude will increase. The operator will continue to shorten the hairspring until the indication shown by the voltmeter reaches a maximum and begins to fall, thus insuring that thepoint of maximum amplitude has been passed. The hairspring is then lengthened slowly until the voltmeterv again shows the maximum reading, and the operation is completed by marking the hairspring in some suitable manner at a point adjacent the rollers to indicate where it should be clamped when the balance-Wheel is assembled. The balance-Wheel may then be removed from the stand, and the operation can be repeated with another balance-wheel.

The method of vibrating or regulating just described gives fairly accurate results, which are good enough for certain kinds of clocks and watches. It will be appreciated, however, that slightly off in frequency and the amount of the l departure by noting the rate at which the wheel goes out of step, but this is a tedious and` timeconsuming process, which is rendered more difcult by the fact that there is nothing to definitely indicate Whether the balance wheel is too fast or too slow at any given instant.

For extremely accurate regulation, therefore, recourse is had to the recording device, the operation and utility of which will now be explained.

This equipment enables exact adjustments to be made with great facility.

Assuming that the balance-wheel 2 is oscillating in its bearings and that the hairspring has been regulated in the manner explained, the large variations in plate current which take place at tube I1 Will result in large variations in plate voltage at this tube. At each oscillation or beat of the balance-wheel, therefore, voltage changes will be transmitted to the grid of tube 28 through the condenser 30 which overcome the normal negative bias on the grid and cause the tube to fire. The condenser 58 is normally charged, 'being connected between ground and the plus'B lead I2 through the resistor 59. When the tube 28 res, or begins to pass current, the condenser 58 discharges over a path which includes the cathode and plate of tube 28 and the electromagnets 56 and 51. The condenser discharges quickly and-the current flow rapidly-decreases to a point where the tube 28 is extinguished and ceases to pass current. The condenser 58 then charges up again through the resistor 59. yThe arrangement thus provides for transmitting short impulses of current to the electromagnets 56 and 51, one impulse for wheel. v

Each time the electromagnets 55 and 51 are energized the printer bar is operated and a mark will be -printed on the paper strip 53,. If the paper feed is started now, the marks will be spaced out lengthwise of the strip on a line the direction of which will indicate to the operator whether the balance-wheel is correct or not, and if incorrect, whether it is too fast or too slow.` Il' the balance wheel frequency is correct, the particular tooth of disc 5I which is used in printing will return to exactly the same point for successive printing operations, and the line of marks will be. parallel to the edge of the paper strip. If the balance-wheel is too slow, the disc 5| will gain on the balance-wheel and the tooth in use will advance a little farther before each printing operation, with the result that the line of marks will trend to the right. Similarly, if the balance-wheel is too fast, the disc 5I will fall behind and the line of marks will trend to the left.

Fig.. 2 shows a fragment of paper strip 80 bearing a printed record 8l of the beats of an oscillating balance-wheel. The record shows that .the frequency of the wheel is correct, as the general-direction of theA line of marks is paralle] to the edge of the strip. The waves in thel line are due to the slight hunting of the balpaper strip. Frequently the balance-Wheel will be found to be correct, due to the preliminary adjustment with the voltmeter, but in any case the departure from the correct frequency will not be great. Thus the final regulation can be made rapidly and to any desired degree of accuracy.

The invention having been described, that which is believed to be new and for which the protection of Letters Patent is desired will be pointed out in the appended claims.

What is claimed is: i 1. Apparatus for use irl-regulating the rate of lan oscillating balance-wheel, comprising means for applying driving impulses to the wheel at the frequencyto which the same is to be regulated, and means for detecting when the oscillations of the wheel reach the maximum amplitude as the associated hairspring is adjusted, said last means including electrical means for generating voltages having a value which is proportionate to the speed of said wheel.

2. Apparatus for use in regulating the rate of a body having` periodic oscillatory motion,

comprising means for applying driving impulses to the body at the frequency to which the periodic motion of the body is to be regulated, and

means sensitive to the speed at which the body is moving for detecting when the body is oscillating with the maximum amplitude, said last means including apparatus for generating eleceach beat of the balance-- component.

trical current which is proportionate to the ampiitude of oscillation of the body.

3. Apparatus for use in regulating the rate of a body having periodic oscillatory motion, comprising means forapplying driving impulses to the body at the frequency to which the periodic motion of the body is to be regulated, means responsive to motion oi' the body for generating electrical energy having a component which varies in proportion to the amplitude of the oscillations of the body, and means for measuring said component. .1 l

4. Apparatus for us in regulating the rate of a body having periodic oscillatory motion, comprising means for setting the body Vin motion by applying driving impulsesthereto at the fre- V quencyto which the rate of the,l body is to be quency to which the rate of the body is tobe regulated, and means effective while the rate of the body is being regulated for determining when the oscillations of the body reach their maximum amplitude, said last means including a photcelectric Vdevice responsive to movement of the .body lbeneath a light bean, means for amplifying the photoelectric currents, the ampliiler output including a component which varies with the amplitude of the oscillations of the body,v vand an instrument for measuring said 16. The combination, for use with a balancefwheel Aand associatedhairspring to be regulated, of a pneumatic device for causing the wheel to oscillate, a photoelectricv device for producing current variations responsive to movement of the wheel, and a meter controlled by said current variations for indicating the amplitude with which the wheel responds to said pneumatic de- `vice. f'

'1. The combination, for use with a balancewheel and associated '-hairspring to lbe regulated,

of'a pneumatic device for delivering impulses of 'speedfelement for reciprocating said nozzle to cause the same to drive said wheel, means responsive to oscillations of the wheel for generating impulses, and means controlled by said yimpulses and cooperating with said element for making a record which indicates whether the rate of the oscillations is fast or `slow with respect to the rate of said element.

9. Apparatus for use in regulating the rate of a member having periodic oscillatory motion,

comprising means for applying constant frequency driving impulsesV to said member, means responsive to movement of the member for generating electrical current, means for utilizing the output of said generating means to produce a sustained electrical potential of a value proportionate to the amplitude of oscillation of the member, means for also utilizing the 'output of said generating means to produce impulses having a freqencyr bearing a fixed relation to the beat frequency of the member, and separate devices controlled by said potential and impulses, respectively, for indicating the relation between the beat frequency and the frequency of said driving impulses.

10. Apparatus for use in regulating the beat frequency of a balance wheel and hairspring comprising means for applying driving impulses to the wheel at the standard frequency for which the wheel is constructed, said wheel being free to oscillate at its naturafrequency, means for continuously giving an indication of the amplitude of oscillation of the wheel while a coarse adjustment is made on the airspring to enable the wheel to respond to the iving impulses at substantially maximum amplitude, and means effective while the Wheel is responding to said driving v impulses for comparing the beat frequency of the impulses and cooperating with said element for` making a record which indicates whether the rate of the oscillations is fast or slow with respect to the rate of said element.

12. Apparatus for use in timing a body adapted for periodic oscillatory motion, comprising means for applying driving impulses to said body tending to oscillate the same at a predetermined constant frequency while permitting the body to oscillate at a different frequency, means for generating electrical energy responsive .to oscillations of said body under the influence of said impulses, and means for utilizing said energy to compare the frequency' of the oscillations of said body with said constant frequency.

13. Apparatus for use in timing an oscillatable body, comprising means for applying driving impulses to said body tending to osclllate the same at a predetermined constant frequency, means responsive to oscillations of said body at a different frequency under the influence of said impulses for generating electrical energy which varies in inverse proportion to the difference between thefrequency of said oscillations and said constant frequency, and an instrument for indicating the difference between said frequencies controlled by said energy.

14. Apparatus for use in timing a body adapte for periodic oscillatory motion, comprising means for applying driving impulses to said body tending to oscillate the same at a predetermined constant frequency, means responsive to oscillations of said body at a different frequency under the influence of said impulses for .generating a train of electrical impulses having a frequency bearing a predetermined relation tothe frequency of said oscillations, and means for comparing the frequency of said electrical impulses with said constant frequency.

15. Apparatus for use in timing a body adapted for periodic oscillatory motion. comprising means for applying driving impulses to said body tending -to oscillate the same at a predetermined constant frequency, means responsive to oscillations oi` said body at a diiferent frequency under the influence of said impulses for producing current variations having an amplitude which depends on natural frequency oscillations for. producing electrical phenomena having a characteristic which depends on said natural frequency, and

means 'for utilizingl said Vcharacteristic to compare said natural frequency with said standard Y, frequency.

the extent to which the frequency of said oscllla-- tions agrees with the said constant frequency,

and means operated in accordance with the amplitude of .said current variations to indicate whether said frequencies are the same or not.

' 18. Apparatus for use lin timing a body adapted for yperiodic oscillatory motion, comprising i means for producing oscillations of said body at itsl natural frequency of oscillation by applying thereto driving impulses having a predetermined standard frequency, means responsive to said 17. Apparatus for use in regulating the rate of an oscillating balance wheel, comprising means for oscillating said wheel at a frequency which is determined by the characteristics ofthe wheel Aand'hairspring, including means for applying to saidnwheel momentary spaced impulses having a frequency which bears a predetermined relation to the correct frequency to which the wheel is to be regulated, the said wheel oscillating freely i.

with anamplitude depending on the extent to which its frequency approximates said correctv frequency, and means for detectingvwhen the os- -cillations of the wheel reach the maximum amhairspring is adjusted.

plitude as the' associated THOMAS B. GIBBS.

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