US2675667A - Stop watch or clock - Google Patents

Description

Patented Apr. 20, 1954 STOP WATCH OR CLOCK Hans Schlenker, S'chramberg, Wurttemberg, Germany, assignor to Gebruder Junghans A. G., Sohramberg, V-Vurttemberg, Germany, a corporation of Germany Application October 17, 1951, Serial No. 251,651

3 Claims. 1

The invention relates to stop watches for time measurements in fractions of seconds, preferably in. ths and /moths of seconds. It is already known to provide a stop Watch, mainly for the measurement of times in /5ths or raths of a second, wherein the shaft of the anchor wheel of the watch mechanism carries, in addition to the pointer or hand, for example, the /5 second hand, a toothed Wheel having one tooth somewhat long r than the others. In this known construction there is, arranged on the shaft. or the customary column. wheel, from which is controlled the zero setting levers for the second hand and the minute hand, a. further separate stepped disc which supports a lever ooacting with the aforesaidv toothed wheel. The coaction is such that upon stopping, the. stepped disc swings the control lever to such an extent that it engages the next gap between any two teeth, which may include the longer one, and thus instantaneously stops the Watch mechanism. Upon setting to zero, the stepped disc allows the control lever to move. back a distance such that it moves out of the. toothed gap in question, but remains in the range of the elongated tooth. The latter thenabuts on the lever after some rotationof the anchor wheel so that the watch mechanism stops. The arrangement is such that the anchor wheel is. stopped on the elongated tooth when the /5 second hand (in this example) stands at zero. 3 A starting lever which cooperates with the column wheel serves the purpose of imparting a starting impulse to the escapement upon starting up the. watch and upon returning the hand indieating fractions of a second when the watch is stopped.

The present invention relates to an improvement in the known construction with regard to measurements of times of ths and fl ths of seconds, the particular nature of the return of the hand indicating fractions of a second into the initial position being effected with the aid of the watch, mechanism. During experiments carried out for increasing the accuracy of the measurement, it has been shown that the starting of the watch mechanism is not guaranteed with the necessary reliability because of the comparatively strong spiral spring whichis necessary for the high number of oscillations of the escapement; similarly, with the stopping of the watch mechanism on a toothed wheel, as occurs in the aforementioned known construction, interferences and inaccuracies are produced. In Order to obviate these disadvantages in accordance with the invention, the column wheel has associated with it a member with which the escapement; is started upon setting the watch in motion, is held when it isstopped and is started again upon being set to zero. The arrangement of this member between the column wheel and the escapement; similarly ensures the reliable starting of the escapement when setting in motion and when returning the pointer indicating fractions of a second, during the zero setting, as well as th momentary stopping of the watch mechanism.

In a preferred embodiment of the invention, the member associated with the column wheel consists in lever coacting with a return spring, two stages of control surfaces being provided partly on the lever and partly on th wheel in order to bring the lever successively from the ready position, with delivery of a starting impulse; into the end position which is opposite in relation tothe escapement, and then half way back from this position into the stop position and finally, with repeated starting, back into the ready position.

A stop-watch for measuring time in ths of a second will now be described with reference to one embodiment and is illustrated in the drawing.

In the drawing,

Figure 1 shows the moving parts and also the hand for indicating fractions of a second with the control devices, the dial plate being removed,

Figure 2 is a section on the line Ii of Figure 1, and

Figure 3 is an elevation of the dial plate.

I, 2, 3, l, 5, 6 represent the mechanism plates of the watch mechanism. Mounted between the mechanism plates 2 and 4'2- is the intermediate shaft '1' which carries the driving gear 8 and which is driven through the latter from the spring casing 3 through the intermediate gears 35', 36, 31, 38. Fast on the shaft i is a further gear 9- which meshes with the gear H] on the shaft H. The shaft 5 i is mounted in the mechanism plates 4 and 5,. passing through the dialled plate [2 and carrying at its free end the pointer or hand [3 for indicating fractions of a second. Also secured on the shaft 51 is the stop finger M which co-operates with the zero stop lever [5. The lever I5 is referred to as a zero stop lever" because its purpose is to stop the hand indicating fractions of a second in the zero position; the

lever I5 is not provided for the purpose of instantly stopping the watch mechanism at the end of a measured time period; the means provided for this purpose will be later described. The zero stop lever [B is. mounted to pivot at it on the mechanism plate I and is under the action of a return spring I! which tends to move it up to th stop pin I8 in the mechanism plate I. The zero stop lever is provided on one of its arms 1511 with a point |b1 which can be brought into the range of the stop finger M on the fractional second shaft H, and is provided on its other arm l5b with control surfaces I5c and l5d which cooperate with control cams l9 on the column wheel 2|] rotatable about the spindle 2| on the plate I. This co-operation between the column wheel and the lever l5 consists in that in the ready position shown in Figure l-which position is identical with the opposite position of the parts after setting to zero-the control surfaces I50, l5d are located between two cams I9, the stop pin [8 thus determining the end position of the lever l5. Upon setting the watch mechanism in movement by depressing the push button 35 and advancing the column wheel 20 by one tooth 20a, the next edge of a cam It strikes the surface 150 and, with the further rotation of the column 20, swings the lever I5 until its control surface [5d bears on the arcuately shaped periphery of the cam. In this position, the lever point l5b1 is retracted from the stop finger I4 and the fractional second shaft I I can rotate freely.

The lever 22 is also mounted on the mechanism plate I so as to pivot about 23. For simplicity in the following description, it is referred to as starting lever 22 but as will be well understood, it has a double function which has yet to be described, namely, one function of starting the escapement and the other of stopping it instantaneously at the end of a measured period of time. The lever 22 is provided with two arms; the return spring 24 engages at 22a and secured to the end of the long arm 22b is the starting spring 25. The spring 25 is made from a thin spring wire which is bent at an angle at the end (Fig. 2) and is so arranged in relation to the circumference of the escapement 21 that, during the swinging past of the escapement, it is able to impart a starting impulse, while in the central position of the lever 22, it stops the escapement and thus the entire watch mechanism.

The escapement 21 is mounted partly in the mechanism plate 3 and partly in the bridge 28 and is connected through the anchor (not shown) with the anchor wheel 29, the shaft 30 of which is mounted at one end in the mechanism plate 6 r and at the other end in the block 3|. Secured to the anchor wheel shaft 30 is the gear wheel 32 which meshes with the wheel 33 on the shaft 1.

The return spring 24 tends to move the starting lever 22 up to the stop pin 26 secured in the mechanism plate I, that is to say, to hold it in the ready position (Fig. l)

The second arm of the starting lever 22, indicated as 220, coacts with the cams 19 of the column wheel 20 and has for this purpose two steps 2201, 2202. These steps are so arranged that they are inoperative in the ready position (Fig. l) and the position of the lever 22 is determined solely by the stop pin 26- and the return spring 24. On the other hand, if the starting lever rests with the step 2201 on th periphery of the next-ioliowing control cam IS, the starting lever 22 is located in an end position opposite to the position shown, the starting end 25a of the starting spring 25 being disposed approximately at the point 34 (Fig. 1), so that the escapement is again free. Finally, if the starting lever 22 rests with the middle step 2202 on the periphery of a control cam IS, the lever 22 is then 4 located in the middle position, that is to say, the starting end 25a of the starting spring bears on the periphery of the escapement 21 and stops this, and therefore the watch mechanism as well. The operation of the devices which have been described is as follows:

1. Starting the watch The watch mechanism is initially in the ready position (Fig. l); the push button 35 is depressed in the direction of the arrow, the column wheel 20 is advanced by one tooth 20a, the cam l9a abuts with its edge on the lever arm 22c, swinging the lever 22 about the pivot 23 until the step 2201 rests on the arcuately curved periphery of the cam I9a. The lever arm 22?) has thus carried out an angular movement, and the end 25a of the spring 25 on the end of said lever is at point 34 (Fig. 1). During the passing movement of the spring 25, 25a, the escapement 21 has received a starting impulse. Simultaneously with the starting lever 22, the zero stop lever I5 is swung by the cam I9b from the stop position (shown in Fig. 1) into the free position, so that the stop finger l4 can move past the point of the lever 15a and the Watch mechanism can commence functioning without hindrance.

2. Stopping For stopping the watch at the end of a meas ured period of time, the push button is depressed a second time, so that the column Wheel 20 is advanced by one tooth 20a and the cam I9a drops on to the second step 2202. Under the action of the return spring, the lever 22 moves to its middle position, in which the end 25a of the starting spring secures the escapement 21; the zero stop lever 15 remains unaffected.

3. Setting to zero When the time has been read off the dial plate 12, on which ths of seconds can be read at [2a, whole seconds at [2b and whole minutes at l2c, the push button 35 is again depressed with the following effect: the cam I9a drops on the step 2202, whereby the column wheel 20 and the lever 22 move out of contact and the lever 22 is displaced by the return spring 24 up to the stop pin 26. Consequently, the lever arm 22b returns from its middle position into the ready position (Fig. 1), that is to say, the end 25a of the starting spring 25 is released from the escapement and gives this a fresh starting impulse. The control surface |5d on the zero stop lever l5 drops off the control cam I9b and the lever l5 returns under the action of the return spring I! to its zero stop position (Fig. 1). The watch mechanism at first continues to run until the stop finger l4 on the fractional second shaft II has moved to the point of the lever arm I5a, which is the case when the hand or pointer I3 is at on the scale [2a.

Simultaneously with the return of the starting lever 22 to the ready position and the lever IE to the zero stop position, the minutes hand 45 and the seconds hand 46 (Fig. 3) are brought into the zero position by means of the twoarmed zero-setting lever 39, which is mounted at 40 on the mechanism plate I and which coacts at 39a with the column wheel 20 and at its free ends 3% and 390 with the zero-setting heart cams 4| and 42 on the minutes shaft 43 and the seconds shaft 44, respectively, and are retained in these positions. These devices are wel known to those skilled in the art.

I claim:

1. In a stop watch having a column wheel and including a watch mechanism, an escapement and a hand associated with a dial indicating fractions of a second, the combination of first means associated with the column wheel for starting the escapement at the commencement of a measuring period and securing it in stopped position at the end of said period and for restarting the escapement for zeroizing the hand, and second means associated with the watch mechanism for returning the hand to zero position on the dial when the escapement is restarted by said first means.

2. A stop watch as in claim 1 wherein said first means comprises a lever, a return spring acting on said lever, and two stages of control surfaces respectively on the column wheel and on said lever, said control surfaces co-operating with each other in opposition to said spring to shift said lever, upon rotation of the column wheel, from a ready position through a stopped position into an end or measuring position, during which movement said lever imparts a starting impulse to the escapement, to shift said lever, upon further rotation of the column wheel, back to the stopped position at which the escapement is secured, and to shift said lever, upon still further rotation of the column Wheel, back to the ready position, during which further movement said lever imparts a second starting impulse to the escapement.

3. In a stop watch according to claim 1, a stop finger mounted on the shaft of the hand indicating fractions of a second, the second means for returning said hand to zero position comprising a lever having a first arm engageable by the column wheel for rotation thereby and a second arm extending into the path of rotation of said stop finger thereby constituting a zeroizing abutment for the shaft of said hand when said lever is rotated.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 67,704 Baker Aug. 13, 1867 FOREIGN PATENTS Number Country Date 597,698 Germany May 29, 1934