CHRONOGRAPHUHR WITH IMMEDIATE ANNOUNCEMENT OF FRACTIONS OF A SECOND

The present invention relates to a device for the display of the fractions of a second, on a separate counter in a mechanical chronograph watch, only when stopping the timing.

In the wristwatches timers can be mechanically driven, there is generally a central second hand driven by the chronograph wheel upon depression of the plunger WebStart, this needle advancing stepwise at the imposed by the sprung balance. If this is 18' 000 oscillations per hour, the needle will put forward 5 not per second, that being at an angle of 1.2 ° pitch. With a dial on the order of 30 mm, this means that at each step the tip of the second hand will move through an arc of about 0.3 mm, length it is distinguishable to the naked eye if there is an additional scale between each second. It will however that reading a measured time to one fifth the second requires some attention to, and that the reading security also depends on the care with which the graduations were generated or décalquées on the dial, as well as the accuracy with which the feet of dial have been adjusted.

For overcoming the disadvantages above, manufacturers have proposed to equip the wristwatches timers can be a mechanical device called "with jumping seconds". The principle is to be displayed on the dial the fractions of seconds on a separate counter with a small needle, driven continuously by a train multiplicative gear, said small needle forming each second full turn, or even 4 or 5 turns according to the complexity of the gear train. Such a device makes the reading procedure, and thus permits an accuracy at one tenth second, but has the disadvantage of requiring a surplus of mechanical energy for driving timing during the time the gear train and the hand. This extra resource energy can be obtained by increasing the dimensions of the barrel, or adding a second barrel, which has the disadvantage of making the construction of the more complex movement, and increasing the weight and dimensions of the chronograph watch.

The invention thus aims to overcome the disadvantages of the prior art mentioned above by providing a mechanical chronograph timepiece having a mechanism for instantaneously displaying, after stopping the timing, the fractions of seconds to add the values indicated by the other counters. Throughout the timekeeping device according to the invention is constructed such that the counter displaying the fractions of seconds is completely disengaged from the drive train, the advantage is gained that considerably reduces the amount of mechanical energy that was needed which was previously mentioned, while providing display with excellent legibility.

To this end, the invention relates to a chronograph timepiece comprising a chronograph movement with a time base of frequency f, control means for starting, stopping and resetting the timing, a dial with analog display by means of a central seconds hand driven by the chronograph wheel which also drives via gear trains the needles of other counters and a needle of a meter comprising a graduation in fractions of seconds. The chronograph timepiece is characterized in that the fractions of a second needle remains stationary throughout the timing and that it is driven in rotation, when stopping the timing, by a sensing arm, pivoted on a platen or deck of the movement, tilting thereof is triggered by the stop means of the chronograph and whose magnitude of the displacement is controlled by the arrival of its catch abutting on a circular cam. The cam ring is driven by the chronograph wheel and comprises the X cams elementary angular aperture[!alfa!] each corresponding to a second. All the cams have a same elementary contour which determines the amplitude of the deflection of the feeler arm and thus the movement of the needle of the meter of fraction of a second in front of a scale determined, the fractionation of the second being a function of the frequency f selected.

Thus, during the entire period of the timing, the fractions of a second counter is decoupled from the drive train, and the additional energy for fractions of a second display is contributed by the re-arming of a spring when performing the counter reset.

As it will be apparent from the detailed description, each cam element may be formed by an inclined plane or by a succession of stages each corresponding to a fraction of a second.

The cam ring may be driven directly by the chronograph wheel by being concentric of said wheel and has then 60 cams elementary angular aperture[!alfa!]=6°. To increase the scanned sector by the needle fractions of a second, the circular cam can also be driven indirectly via a pinion meshed with the chronograph wheel in a multiplicative ratio the K such as K&Miniature bull; x=60.

The needle of fractions of seconds may be driven directly by the feeler arm or by a secondary arm fixedly connected thereto. It may also be driven indirectly via a rack secured to said sensing arm and the sector gear which meshes with a pinion itself driving the needle fractions of a second.

It should be noted also that, allow free rotation of the cam during timing, the stylus must lie outside the envelope of rotation of the cam, thereby causing the needle fractions of a second to move on to a neutral position "n-" before the position 0 of the counter. However, by minimizing the distance between the feeler and the envelope, the positions "d" and "0" can be visually confused, which is particularly advantageous for a counter with a circular dial.

The mechanism and causes the control timing (start, stop and reset) may be those known prior, such as a column wheel acting on a lever fixed to the sensor arm.

Other features and advantages of the invention will appear in the following description of several examples, given by way of illustration and not as a limitation, with reference to the accompanying drawings in which:

• figure 1 is a plan view of a chronograph timepiece according to the invention;
• figure 2 is an enlarged representation at the chronograph wheel of a first embodiment of a mechanism according to the invention in the on position;
• figure 3a is an enlarged representation of a portion of a first variation of the mechanism of Figure 2 at the arrow-III;
• figure 3b is an enlarged representation of a portion of a second variation of the mechanism of Figure 2 at the arrow-III;
• figure 4 is an enlarged representation at the chronograph wheel of a second embodiment of a mechanism according to the invention in the on position;
• figure 5 represents the same mechanism as that of Figure 4 in the off position;
• figure 6 represents the same mechanism that Figure 4 in reset position, and
• figure 7 shows a third embodiment, illustrating further variants of a mechanism according to the invention.

According to the embodiment shown in Figure 1, a stop-watch includes a dial 2 indicating the current time using a 3 hour hand, a minute hand 4, and a small second hand 5 off-centered on a dial 15 located at 6:00. For the timing function, the watch also includes a central second hand 6, a counter 17 indicating the fractions of seconds using needle 7 and a counter 18 showing minutes using needle 8. the chronograph watch has finally on its middle part 9 a ring 12, a pusher 11 for starting and stopping and a pusher 13 for the reset. In known manner, the pushers 11 and 13 could be replaced by a single pusher triple acting. The chronograph watch has obviously a chronograph movement frequency f, not shown as being well known to the skilled person.

Referring now to Figures 2, 3a and 3b, is described below a first embodiment of a mechanism which is shown that the useful parts to the understanding of the invention, Figure 2 corresponding to a start position. The stop positions and reset will be explained further with reference to Figures 4, 5 and 6 corresponding to a second embodiment.

The motive member is the chronograph wheel 10 which supports and drives a circular cam 20 said cam ring 20 is formed by a chain of the X elementary cam 22, having an angular opening[!alfa!] corresponding to a second, c'est to say in this case of 6°. These cams elementary 22 are intended to cooperate with a sensor arm 27. The circular cam 20 can be a separately produced part and then concentrically fixed on the chronograph wheel 10. It can also be formed integrally with the chronograph wheel 10.

As seen in Figure 3a, a cam element 22 is formed by a succession of stages 23i each corresponding to a fraction of a second. In the example shown in Figure 3a, can be counted 5 stages respectively corresponding to 0, 1/5, 2/5, 2/5 and 4/5 of second adding to elapsed time. To this end, selected for example a frequency corresponding to 18' 000 oscillations per hour, either 5 shots per second.

In the variant shown in Figure 3b, a cam elemental 22 merely comprises an inclined plane 25, and the cam ring 20 is formed by a solid disk.

The circular cam 20, each cam element 22 respectively, is for receiving, when stopping the timing, a sensing arm 27 pivoted on an axis 28, and of which the mouthpiece 29 falls on a stage stop 23i or along the inclined plate 25 by rotating the needle of fractions of seconds 7 which is secured thereto so as to position it opposite a scale 0, 1, 2, 3 or 4 of the counter 17. The counter 17 has, before the scale of O, a graduation "d" corresponds to a neutral position in which the spout 29 of the feeler arm 27 completely disengages from the cam 20 by allowing free rotation of the chronograph wheel 10. By minimizing the distance between the end of the spout 29 and the outermost edge of the cam 20, the graduations may be used O and n substantially merged.

As shown in Figure 1, it is also possible to conceal the scale N using an adapted cutout in the dial 2.

The sensor arm 27 is biased away from the cam 20 by a control arm 31 whose end 31 a is held by a spring 32 bears against a column of a column wheel 33i 30 having teeth drive 34i. The sensor arm 27 is further provided with a secondary arm 35 having at its end a pin 36 intended to cooperate with a latch 40 pivoted on an axis 41, said flip-flop 40 is maintained in the position shown by a retaining pin 42 and for resetting the counter 17 by means of a shift finger 43, as will be explained with reference to Figures 4 to 6.

The flip-flop 40 also has two arms 44, 46 having two hammers at their ends 45, 47 reset hearts (not shown) of other counters.

Referring now to Figures 4, 5 and 6 is described below a second embodiment in which the same or similar parts are designated by the same references.

Figure 4, which corresponds to Figure 2 in the on position, shows two essential differences at indirect drives the cam and the needle fractions of a second.

See firstly that the circular cam 19, formed by the chaining the X elementary cams each corresponding to a second, is unsupported directly by the chronograph wheel 10, but by a drive pinion 21 n₂ teeth meshing with the teeth 14 of the chronograph wheel teeth including Ni, c'est to say in a multiplicative ratio gear k=n₁/ N.₂ . This K ratio must be an integer divider 60, so that a complete rotation of the drive gear 21 corresponds to an integer the X second, c'est to say in fact at X number of elementary cams 22. in other words the number X of cams elementary, multiplied by the gear ratio is K, must be 60 seconds which corresponds to the equation K x=60.

In the example illustrated, it is shown that the cam 19 has 6 elementary cam 22, which corresponds to a gear ratio k=10, it is not possible to have a chronograph wheel 10 with n₁ =160 teeth and a drive pinion 19 with n₂ =16 teeth. Other choices are obviously possible. It would be particularly desirable to have a chronograph wheel the n₁ =180 teeth so as to construct a mechanism having from 2 to 6 cams elementary, simply by choosing the driving pinion 19 having respectively 6, 9, 12, 15 or 18 teeth.

This embodiment also has the advantage of providing elementary cams having an angular opening[!alfa!] large (in the example illustrated 60°) for arranging the stages easier 23i or the inclined plane 25. It also allows to have stages 23i (respectively an inclined plane 25) deeper by providing a larger clearance at sensing arm 27 and correspondingly to the needle 7 fractions of a second, in the case where it would be, as in the first embodiment, integral with the sensor arm 27. The graduations of the counter 17 may then be spaced further apart, for ease of reading. In the example illustrated, it is shown that the graduations are from 0 to 5, corresponding to a second fractionation in 1/6. To this end, each cam 22 has 6 stages 23i elementary and selecting one of 21600 oscillations per hour.

This second embodiment also differs from that described in the first fractions of a second needle 7 is not directly driven by the feeler arm 27, but indirectly by a rack 37, integral with said feeler arm 27, and the sector gear 38 which meshes with a pinion 39 carrying the needle 7 fractions of a second and pushing it in rotation. The addition of the rack 37 has the advantage of further amplifying the displacement of the needle fractions of seconds 7 and give more freedom in positioning the counter 17 on the dial 2.

5 to Figure has now represented the position of the mechanism when the timing is stopped. The column wheel 30 rotates and, under the action of the spring 32, the spout of the control arm 31a 31 falls between the two columns 33_{the I} 33 and_{i + 1} by releasing the sensor arm 27 to swing will be limited by the arrival of its catch 29 abutting on a stage 23i a cam 22 of the cam 20 elementary. This tilting motion also drives the rack 37 of which the sector gear 38 will rotate the pinion 39 which controls movement of the needle on the dial 7 17 opposite a scale corresponding to the stage 55_{the I} on which the probe 37 abuts.

Figure 6 shows the position of the mechanism when performing the reset, c'est to say in fact when returns the needles 6 and 8 to zero by means of hammers 23 and 25 acting on cores (not shown) and the fractions of a second needle 7 in the neutral position n this maneuver is performed by pressing the pusher 13 to pivot the lever 40 and exert, via the finger 43, a pressure on the pin 36 of the arm 35 to toggle the rack 37 and hold it, without intervention of the column wheel 30, in a rest position in which the beak of the feeler arm 29 27 again permits free rotation of the cam 19. The needle 7 is moved back into the neutral position n by rotationally driving the pinion 39 by the sector gear 38 of the rack 37.

When effecting a new timing, the column wheel 30 to advance by one pitch, thereby causing the unblocking of the pin 36, and blocking the end 31a of the arm 31 on a column 33i wheel column 30, as shown in Figure 4.

Figure 7 represents a second embodiment which illustrates possible variations of the display mechanism of fractions of seconds according to the invention.

In the embodiment shown, see that the cam 19 has 4 cams elementary 22 (x=4), corresponding to a gear ratio k=15, and enables for example have a chronograph wheel 10 to 180 teeth (N.₁ =180) and a drive pinion 21 to 12 teeth (N.₂ =12). As seen, by decreasing the number of cams elementary 22, an increased possibility to fractionate a second. In the example shown in Figure 7, it is shown that each cam element has 10 stages 23_{the I} , which means that the fractionation in tenths of a second, if at all use a frequency of 36000 oscillations per hour. With this same frequency could also be designing a cam elemental having only 5 stages for a timing out 1/5 second and for correcting the defect engagement initially.

The same result could be obtained with a frequency of 28800 oscillations per hour for a timing out of second 1/4.

In another embodiment shown in Figure 7, it is shown that the drive gear 39 is replaced by a train of gears 24 multiplicative, 26, so that the needle 7 fractions of a second driven by the driven gear 26 may scan all around a circular dial 17 of the counter. This construction also has the advantage of reversing the direction of rotation of the needle 7 and thereby provide a display in the clockwise direction.

It is clear to the skilled person that other modifications may be at mechanism just described without departing from the scope of the invention, for example by combining together the variants which have been mentioned.