US3010075A

US3010075A - Electric watch

Info

Publication number: US3010075A
Application number: US760243A
Authority: US
Inventors: Epperlein Helmut
Original assignee: Hamilton Watch Co
Current assignee: Hamilton Watch Co
Priority date: 1958-09-10
Filing date: 1958-09-10
Publication date: 1961-11-21
Anticipated expiration: 1978-11-21

Description

Nov. 21, 1961 H. EPPERLEIN 3,010,075

ELECTRIC WATCH Filed Sept. 10, 1958 Fig. 2.

INVENTOR He/muf E pper/e/n io/Wm; f 0826M ATTORNEYS 3,010,075 Patented Nov. 21., 1961 United States Patent Ofiice This invention relates to electric watches and more particularly relates to the driving device for small watches of the wrist watch type. g

In the powering of electric watches, it has been proposed to utilise an arrangement in which an armature :consisting of apermanent magnet -is arranged in an air jgap between the polesof an iron core having two coils ;wound thereon. These two coils form the input-and output coils of an amplifier which is controlled by the currents induced in the input coil "and, develops a current in the output coil which powers the armature. Such a device might be provided with a brake limiting the rotational speed of the armature which runs constantly in a single direction like the armature of a conventional motor with the direction of rotation being determined by the direction in which the armature started to rotate.

The present invention relates to a device for driving electric watches which is characterized by a balance wheel similar to those used in an ordinary spring watch and is provided with a conventional hairspring. In addition to these conventional features, the balance wheel is also provided with a bar of soft iron or other magnetic material extending parallel to the horizontal plane of the balance wheel. This bar is installed in the air gap 7 between the poles of an iron core having two coils wound thereon. The two coils constitute the input and output coils respectively of an amplifier acting in the manner of a blocking oscillator and controlled by the current induced in the input coil with the output current driving the balance wheel. According to the invention,

the bar of soft iron creates a variable coupling between the input and output circuits depending upon the momentary position of the balance wheel. The magnitude of oscillation of the balance wheel is determined in a well known manner by the moment of inertia of the wheel, including its bar of soft iron, and by the power which is stored in the hairspring.

It is accordingly a primary objectof the present invention to provide an improved device for'powering a small electric watch.

It is another object of the invention to provide an improved device for powering an electric watch utilizing a transistor in a blocking oscillator type circuit.

It is still another object of the invention to provide an improved device for powering an electric Watch comprising a magneticmember oscillating with the balance wheel and installed in the air gap of a magnetic core having two coils which constitute the input and output coils respectively of a transistor amplifier operating in the manner of a blocking oscillator.

These and further objects and advantages of the invention will become more apparent upon reference to the following specification and claims and appended drawings wherein:

FIGURE 1 is a plan view, partly diagrammatic, showing an electric watch powering device of the type comprehended by this invention; and

FIGURE 2 is a partial vertical cross-section showing the construction of the balance wheel and magnetic bar.

Referring to FIGURE 1, there is shown at 10 a generally semi-circular iron core having pole shoes 11 and 12 and having an input coil 13 and an output coil 14 wound thereon. The input coil 13 may, as an example, consist of approximately 12,000 turns of a wire 0.03 mm. in diameter while the output coil 14 may comprise approximately 18,000 turns of a wire of the same diameter. The self capacity of the two

coils

13 and 14 is indicated in FIGURE 1 by the capacitors 13a and 14a which are shown connected into the circuit by means of broken lines. i I

The amplifier itself consists of a PNP contact transistor 15 whose emitter is indicated at E, whose collectoris indicated at C and whose base is indicated at B. This transistor may be of the C0340 type, manufactured by the lntermetall Company ofGermany. Other equivalent transistor types may of course be utilized. h

This transistor provides "a current amplification of more than 30 when connected in the emitter circuit which is shown. It is necessary that natural oscillation be prevented and thus in some instances it maybe desirable, although not essential, to connect a resistance 16 .be-

- tween the emitter and base as shown in FIGURE 1,

depending upon the temperature. The emitter and base are connected respectively to the upper and lower terminals of the input coil 13 while the collector is connected to the lower terminal of the output coil 14. The upper terminal of the output coil 14 and upper terminal of the input coil 13 are respectively connected to the negative and positive terminals of a small primary battery 17 which may, as an example, have a voltage of 1.5 volts.

Mounted between the pole shoes 11 and 12 and supported by a conventional bridge 24 and pillar plate 25 is a balance wheel 18 which is of the same construction as that found in conventional watches. Also conventional is a hairspring 19 connected at one end to the balance staff 22 and at the other end to. a suitable stud 22a on the bridge 24. Suitable jewel bearings 23 may be provided for cooperating with the pivots 21 on the balance staif 22.

Mounted on the balance staff 22 below the balance wheel 18 is the soft iron bar 20 which extends from one pole piece "11 to the other pole piece 12 as is seen in FIGURE 1.

The device shown in the figures of the drawings operates in such a manner that he bar of soft iron creates a variable coupling between the output coil 14 and input coil 13 of theampliiier. This coupling is relatively strong when the bar of soft iron occupies the position shown in FIGURE 1 but is relatively weak when the bar is withdrawn from this position. In operation, the amplifier goes into a strong oscillation which causes a brief magnetization of the bar when it is in the position shown in FIGURE 1, and the balance wheel is at this time pushed out of this line by the action of the power created between the ends of the bar and the pole shoes at each passage through this position. This eifect resembles that of a blocking oscillation inasmuch as such an oscillator also undergoes an intermittent large amplitude oscillation.

The duration of the oscillation of the balance wheel is determined by its moment of inertia and by the power of the hairspring 19 as in the case of an ordinary watch equipped with a balance wheel. Of course, the moment of inertia of the bar 20 supplements that of the balance wheel in determining the period of oscillation.

The energy of oscillation which is lost through friction is replenished from the battery 17 by means of the amplifier so that the balance wheel undergoes undamped oscillations which extend through an angle of approximately 310 degrees.

The invention may be embodied in other specific form's without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by; the appended claims rather than by the foregoing description, and all changes which come Within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. In a battery powered watch having a balance staff and hairspring, a magnetic bar mounted on said balance 'stafi and extending diametrically thereacross for oscillation therewith, a magnetic core having opposite pole pieces diametrically opposed with respect to said balance staff and in close proximity to the ends of said bar, said c'ore being generally arcuate in form, an input coil of said input coil adjacent said pole pieces being connected to the base of said transistor, the other end of said input coil being connected to the emitter of said transistorand to the positive terminal of said battery, the end of said output coil adjacent said pole being connected to said collector, the other end of said output coil being connected to the negative terminal of said battery, and said bar forming a variable coupling between the input and output circuits of said amplifier whereby it acts as an oscillator with the input coil controlling the oscillator and the output coil drawing power therefrom to sustain the balance staff in oscillation.

2. A battery powered watch as set out in claim 1 including a resistor connected between the emitter and base of said transistor to prevent natural oscillation.

References Cited in the file of this patent UNITED STATES PATENTS 2,769,946 Brailsford Nov. 6, 1956 2,831,114 Van Overbeek Apr. 15, 1958 2,845,772 Beyner Aug. 5, 1958 2,877,399 Shaull Mar. 10, 1959 FOREIGN PATENTS 785,749 Great Britain Nov. 6,-1957