GB2448735A

GB2448735A - Timepiece regulator

Info

Publication number: GB2448735A
Application number: GB0708066A
Authority: GB
Inventors: Kevin John Richard Jones
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-04-26
Filing date: 2007-04-26
Publication date: 2008-10-29
Also published as: GB0708066D0

Abstract

A timepiece comprising a filter which has a natural frequency and a timebase source capable of producing a second frequency, functionally connected to the filter such that the filter resonates at the second frequency. Preferably the timepiece includes an amplifier disposed between the filter and the timebase source. The amplifier may be an escapement mechanism or electromagnet and the filter may be a pendulum or balance wheel. The timebase source may comprise a quartz crystal, radio time signal or an RC oscillator and a source derived from the mains electricity frequency. The timepiece may include means of measuring regularity and disconnecting the timebase source if it falls outside acceptable values. The timebase source may be retrofit to the timepiece.

Description

* 2448735

I

Timepiece The invention relates to the field of timepieces, and in particular to improved regulation for timepieces.

Owners of historic timepieces are often disappointed with their accuracy, even when they are in perfect working order. The problem is not so much to do with the speed of the timepiece under steady conditions, which can generally be adjusted at will. It is more a question of the stability of the timepiece under lOvarying conditions of temperature and humidity and, in the case of timepieces installed in vehicles, movement. Restorers sometimes discard original mechanisms and replace them with modem quartz movements. This neither looks nor sounds right. The present invention comprises a technique for keeping the original mechanism, but providing it with any required modern I5standard of accuracy.

Any oscillator, whether mechanical, electronic or otherwise, may be thought of as a combination of a filter and an amplifier (fig. 1). The purpose of the filter is to resonate at one frequency and one frequency only, in order to provide a 2Ostable basis for the timing function. The purpose of the amplifier is to take the signal from the filter, amplify it to compensate for any fnction or other energy loss and feed it back into the filter, thus maintaining the oscillation indefinitely.

In a traditional clock, the filter is the pendulum or balance wheel and the amplifier is the escapement. In the many known standard electronic oscillator 2sdesigns, the fitter is comprised of capacitors and resistors or inductors and the amplifier is usually transistor-based.

A filter can be made to resonate at frequencies slightly different from its natural frequency. The ability of a filter to reject frequencies other than its natural 3Ofrequency is referred to as its quality factor or Q factor (fig. 2). Parameters affecting the Q factor include friction in mechanical oscillators, and resistance of the components in electronic ones.

The filters in historic timepieces generally have (a) natural frequencies which vary considerably with temperature, humidity and movement and (b) fairly low Q factors. Because of (b), they can be made to resonate at frequencies slightly different from their natural frequencies fairly easily.

According to a first aspect of the invention, there is provided a timepiece comprising a filter having a natural frequency and a timebase source capable of producing a second frequency, and functionally connected to the filter such that the fitter resonates at the second frequency. This allows the fitter to oscillate at lOthe frequency of the timebase source, even if that frequency is not the same as the natural frequency of the filter.

The timepiece may include an amplifier disposed between the filter and the timebase source.

Preferably, the timepiece further comprises measuring means to measure the regularity of the running of the timepiece, and means to determine if this regularity is within acceptable values. Means are provided to disconnect the timebase source and close a feedback loop if it is determined that the regularity 2Ohas fallen outside acceptable values. In this event, the timepiece will not provide the accuracy of the timebase source, but it will run with good regularity at the natural frequency of the filter, with all oscillations being of similar period and amplitude. Means are provided to re-open the feedback loop and re-connect the timebase source once it is determined that the consistency of 25running has returned to acceptable values.

According to a second aspect of the invention, there is provided a timebase source for retrofitting to a timepiece, the timepiece comprising a filter having a natural frequency, the timebase source comprising means to generate a second 3Ofrequency and means to functionally connect the timebase source to the filter such that, once connected, the filter is arranged to resonate at the second frequency.

According to a third aspect of the invention, there is provided a method of modifying a timepiece, the timepiece comprising a filter having a natural frequency and an amplifier. The method comprises opening a feedback loop between the fitter and the amplifier, and functionally connecting a timebase 5source producing a second frequency to one of the filter and the amplifier, such that the filter oscillates at the second frequency.

In order that the invention may be more fully understood, a preferred embodiment in accordance with the invention will now be described, by way of lOexample, with reference to the accompanying drawings, in which: Figure 1 illustrates schematically an oscillator; Figure 2 illustrates schematically a graph of response against frequency I Sshowing a quality factor Q of a filter; Figures 3a and 3b illustrate schematically two alternatives for opening the feedback loop of the oscillator of figure 1 and connecting an independent timebase source; Figure 4 illustrates schematically a known mechanically impulsed electric clock; Figure 5 illustrates schematically the mechanically impulsed electric clock of figure 4 having an independent time base according to an embodiment of the invention.

According to one specific embodiment of the present invention, there is provided a mechanically impulsed electric clock, with a balance wheel, an 3oelectromagnet and an electrical contact. The original design is such that, every time the balance wheel passes its centre position, a pin on the balance wheel brushes against the contact, momentarily completing a circuit and sending a current through the coil of the electromagnet (fig. 4). Thus the balance wheel is the filter and the electromagnet is the amplifier.

The present invention is applied to this clock as follows. First, the connection between the electromagnet and the contact is removed. Instead, the electromagnet is impulsed by a regular signal generated by a microcontroller, 5with its timing controlled precisely by a quartz crystal. The original contact is connected to an input port on the microcontroller, which is able to detect from this whether the clock is running regularly and at the correct speed (fig. 5).

Parameters that can be monitored by the microcontroller include the consistency of the time delay between pulses from the contact, and the time lOtaken for the contact to brush past the pin (which provides an indication of the amplitude of the oscillation). If it is detected that the clock is not running with good regularity, the feedback loop is closed, the signal from the contact is copied to the electromagnet and the clock runs at the natural frequency of the balance wheel. Once the microcontroller detects that the clock is running lscorrectly, the feedback loop is opened again, and impulses generated accurately by the microcontroller are fed to the electromagnet.

It will be appreciated by those of skill in the art that various modifications may be made to the above described embodiment without departing from the scope 200f the present invention. 5

Claims

CLAIMS: 1.

51.A timepiece comprising: a filter having a natural frequency; and a timebase source capable of producing a second frequency, and functionally connected to the filter such that the filter resonates at the second frequency.
2. A timepiece as claimed in claim 1, further comprising an amplifier disposed between the filter and the timebase source.
3. A timepiece as claimed in claim 2, wherein the amplifier is an escapement mechanism and the filter is a pendulum.
4. A timepiece as claimed in claim 2, wherein the amplifier is an electromagnet and the fitter is a balance wheel.
205. A timepiece as claimed in any one of the preceding claims, wherein the timebase source is selected from one of a quartz crystal, a radio time signal, an RC oscillator, and a source derived from the mains electricity frequency.
256. A timepiece as claimed in any one of the preceding claims, further comprising means to disconnect the timebase source and close a feedback loop between the filter and an amplifier.
7. A timepiece as claimed in claim 5, further comprising: measuring means to measure the regularity of the time piece; means to determine if the regularity is within acceptable values; means to disconnect the timebase source and close the feedback loop if it is determined that the accuracy has fallen outside acceptable values; and means to connect the timebase source to one of the filter and amplifier and open the feedback loop if it is determined that the regularity is within

acceptable values.
8. A timebase source for retrofitting to a timepiece, the timepiece comprising a filter having a natural frequency, the timebase source comprising: means to generate a second frequency; means to functionally connect the timebase source to the filter, wherein once connected the filter is arranged to resonate at the second frequency.
9. A method of modifying a timepiece, the timepiece comprising a filter having a natural frequency and an amplifier, the method comprising: opening a feedback loop between the filter and the amplifier; and functionally connecting a timebase source producing a second frequency to one of the filter and the amplifier, such that the filter oscillates at the second frequency.
10. A timepiece substantially as described herein with reference to figures 3 and 5 of the accompanying drawings.
11. A timebase source for retrofitting to a timepiece, the timebase source substantially as described herein with reference to figures 3 and 5 of the accompanying drawings.

3012. A method of modifying a timepiece, the timepiece comprising a filter having a natural frequency and an amplifier, substantially as described herein with reference to figures 3 and 5 of the accompanying drawings.