GB2482360A

GB2482360A - Irregularly driving unidirectinal motors for enhanced data display in timepieces

Info

Publication number: GB2482360A
Application number: GB1018837.3A
Authority: GB
Inventors: Richard George Hoptroff
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-11-08
Filing date: 2010-11-08
Publication date: 2012-02-01
Anticipated expiration: 2030-11-08
Also published as: GB201018837D0; GB2482360B

Abstract

A timepiece has a stepper motor driver to indicate the progression of time as a regular series of pulses. The stepper motor is controlled by a pulse generator which can operate at two different frequencies. The frequency used is selected according to the position of a pointer, preferably indicating the date, in comparison to an electronic time reference. When the date is wrong a high frequency burst of pulses is emitted to move the pointer until it displays the correct date.

Description

DEVICE FOR IRREGULARLY DRIVING UNIDIRECTIONAL MOTORS FOR ENHANCED

DATA DISPLAY

This invention relates to the use of unidirectional watch and clock stepper motor drivers to indicate the progression of time as a regular series of pulses. The invention pulses the motor slightly irregularly in order to convey additional information.

Clocks and watches display, primarily, the passage of time. A typical analogue electronic device uses a stepper motor that is excited at regular intervals. The constant rate of stepping is translated by means of gearing to a display based on moving elements such as pointers (e.g. hours, minutes and seconds hands) and plates (e.g. 31-day date window).

Such gearing is either rationally linear (i.e. elements move in repeating cycles with periodicities related by ratios of integers) or a step-wise derivative of the same (e.g. a date plate that steps one position at midnight).

One measure of state of the state of art of such electronic circuits may be regarded as US Patent 4014164, most commonly embodied in the PCA2000 integrated circuit produced by NXP Semiconductors. In normal operation, it produces one pulse per second. When the battery is low, it instead issues a burst of four pulses every four seconds. This alternate, regular pattern results in a stepping motion that is jerkier but maintains the basic time indication. The electronic circuit does not store a count of where it has moved the elements in the time display; it simply drives the motor according to a regular pattern. Consequently, the additional low battery' information is unarguably conveyed by the characteristics of the motion of the moving elements rather than their resulting positions.

This invention relates to a method of irregularly driving a stepper motor to convey extra information or to modify the nature of the information displayed according to the state of an internal counter. US Patent 4271494 discloses a similar method to achieve similar goals, but requires series of irregular pulses that alternately drive the motor forwards and backwards. This invention differs in that it requires forward driving alone and deriving the desired result by a different mechanism and sequence of events, US Patent 4271494 does not consider this possibility despite it being possible to implement it using the circuit elements discussed in US Patent 4271494. Therefore it is reasonable to claim that the present invention is novel with respect to US Patent 4271494, and is not an obvious development from it.

Likewise, clocks exist that adjust for daylight saving time on the basis of external signals received such as from a radio source or an internet connection. Such devices do not even consider the possibility of obtaining the same result on the basis of the value of an internal counter alone, despite it being possible to implement it using the circuit elements used in such clocks. Therefore it is reasonable to claim that the present invention is novel with respect to such clocks, and is not an obvious development from them.

According to a first aspect of the present invention, there is provided a timepiece, having a pointer, comprising a pulse generator, configured to be in a first state and a second state, wherein the pulse generator operates at a first frequency in the first state and at a second frequency in the second state, an electronic time reference, a pointer position reference, a driving circuit, including a frequency selector, wherein the frequency selector is configured to select the first or second state on comparison of the pointer position to the electronic time reference, and a stepping motor, configured to drive the pointer at the selected frequency.

According to a second aspect of the present invention, there is provided a method of driving a pointer on a timepiece, the timepiece having an electronic time reference, the method comprising the steps of comparing the position of the pointer to the electronic time reference, selecting a first frequency or a second frequency according to the comparison of the pointer to the electronic time reference, and driving the pointer at the first or second frequency.

Accordingly, and with reference to figure 1, the invention is the following device: 1. An electronic circuit (101' in figure 1) drives unidirectional stepper motor (102'), which, possibly by means of gearing (103') drives mechanical display elements (104'), with reference to a regular timing component such as a crystal oscillator (105').

2. Electronic circuit (101') maintains an up-to-date count (106') of the time and the number of pulses imparted to the stepper (102').

3. The circuit generates stepper motor pulses that are irregular in timing but which are sufficiently close to being regular that a regular progression of time is indicated by one or more moving elements, while the irregularity, derived from counter (106'), conveys additional information or modifies the information conveyed according to the resulting position of the moving elements.

Embodiments of the invention would generally take the form of microcontrollers configured to count the moving element position and generate the irregular pulses required. The intent is to enhance the amount of information conveyed by existing watch and clock movements through the use of more sophisticated driving circuitry. Example embodiments include: 1. With reference to figures 1, 2 and 3, motor driver circuitry (101') generates regular pulses once per second. This drives a stepper motor whose axis completes a rotation after 60 pulses and is connected to a second hand that completes a rotation every minute. In addition, it is connected to reduction gearing in the ratio 60:1. The resulting axis completes a rotation every 3600 pulses, or once per hour, and is connected to a minute hand. This in turn is connected to reduction gearing in the ratio 12:1. The resulting axis completes a rotation every 43200 pulses, or once per twelve hours, and is connected to an hour hand. This in turn is connected to stepped reduction gearing in the ratio 62:1, such that it promptly advances a plate by) of a rotation after 86400 pulses, or 24 hours, and completes a rotation every 2678400 pulses.

In months with 31 days, the regular once-per-second pulse rate is maintained so that the plate completes a rotation every 31 days (201' and 203' in fig 2, 301', 302', 303' and 304' in fig 3).

In months with 28 days, the regular once-per-second pulse rate is maintained through the course of the month, so that by the end of the 28th day the plate has advanced by 2i of a rotation. When motor driver circuitry (101') determines, by comparing its count (106') of date and time to the rules pertaining to month lengths, that it is end of the 28th day of a 28-day month, it generates a rapid series of 259200 pulses so that the plate completes its rotation (202'; 303', 305') and returns to the position it had at the beginning of the month. Motor driver circuitry (101') then issues a further number of rapid pulses, equal to the number of seconds it took to issue the 259200 pulses, such that the seconds, minutes and hour hands are sent forward to the positions they would have attained had the regular once-per-second pulse rate been maintained (306', 304').

In months with 29 days, the motor driver circuitry (101') determines, by comparing its count (106') of date and time to the rules pertaining to month lengths, that it is end of the 29th day of a 29-day month, and similarly generates a rapid series of 172800 pulses followed by as many rapid pulses as seconds required to send forward the seconds, minutes and hour hands to the positions they would have attained had the regular once-per-second pulse rate been maintained.

In months with 30 days, the motor driver circuitry (101') determines, by comparing its count (106') of date and time to the rules pertaining to month lengths, that it is end of the 30th day of a 30-day month, and similarly generates a rapid series of 86400 pulses followed by as many rapid pulses as seconds required to send forward the seconds, minutes and hour hands to the positions they would have attained had the regular once-per-second pulse rate been maintained.

The net effect is that the plate, if depicting the date, corrects for months of differing numbers of days while the second, minute and hour hands remain largely unaffected.

In practice, the rapidity of the irregular pulses is likely to be of the order of 64Hz.

Correction of the date indication in this way would take 22% minutes for each day the plate had to be advanced, during which time the display is not useable. Therefore the correction might be configured to take place at, for example, three o'clock in the morning, rather than at midnight.

2. With reference to figures 1, 4 and 5, motor driver circuitry (101') generates regular pulses once per second. This drives a stepper motor whose axis completes a rotation after 3600 pulses and is connected to a minute hand that completes a rotation every hour. In addition, it is connected to reduction gearing in the ratio 12:1.

The resulting axis completes a rotation every 43200 pulses, or once per twelve hours, and is connected to an hour hand. This in turn is connected to stepped reduction gearing in the ratio 62:1, such that it promptly advances a plate by of a rotation after 86400 pulses, or 24 hours, and completes a rotation every 2678400 pulses (501', 502', 503' and 504' in fig 5).

This mechanism is considered because it is commonly available, not because it is ideal. The intent, however, is to advance the plate with a period that remains, within the 31-position stepping accuracy, synchronized with the synodic month. The synodic month is the time from one new moon to the next, a quantity whose long-term average duration is Ps 29.530589 days, which is not easy to derive by means of gearing from one-second pulses of the stepper motor, but can be used to depict various quantities related to the synodic cycle such as tides.

Accordingly, rather than being used for date display (401'), the plate is adapted to depict a quantity that varies with a period related to the synodic month, such as a tide

table (402').

Clearly if the mechanism is pulsed once per second, the plate will complete a rotation in 31 days and will fall behind the desired position. Motor driver circuitry (101') determines when, by reference to its internal count (106') of the time, plate is being advanced S days late of the most accurate approximation to the synodic cycle. 31x4

It issues a rapid series of 43200 pulses (403', 503', 505'). Motor driver circuitry (101') then issues a further number of rapid pulses, equal to the number of seconds it took to issue the 43200 pulses, such that the minutes and hour hands are sent forward to the positions they would have attained had the regular once-per-second pulse rate been maintained (506', 504'). Mechanism driving plate 403' will have been advanced one half of one position and may or may not have advanced the plate the process, but plate will now be aligned to advance days sooner than most 31x4 accurate approximation to the synodic cycle, with the lead slowly dropping off to become a lag over time.

The net effect is that the 31-day element in fact completes a rotation that closely approximates the synodic cycle period Ps while the 60-minute and 12-hour elements remain largely unaffected. The frequency with which the corrective step needs to be applied is: Pxl3/ 24 10.04844 days (31 -i) In practice, the corrective step might be applied at an unobtrusive moment, e.g. at three o'clock in the morning, rather than at the exact time that would be most accurate. This is not just to avoid distracting the user, but also to reduce the frequency with which power is consumed in performing the required calculations.

In practice, the movement may well be a secondary display for a dual time zone. If the user decides to modify the time zone depicted, the position of the plate element may inadvertently become out of sync. If this is the case, the counter value (106') is modified in order to compensate accordingly.

3. With reference to figures 1, 6 and 7, motor driver circuitry (101') generates regular pulses once per second. This drives a stepper motor whose axis completes a rotation after 3600 pulses and is connected to a minute hand that completes a rotation every hour. This in turn is connected to reduction gearing in the ratio 12:1.

The resulting axis completes a rotation every 43200 pulses, or once per twelve hours, and is connected to an hour hand (601').

In normal operation, the regular once-per-second pulse rate is maintained (601', 701', 702', 703', 704' and 705').

When motor driver circuitry (101') determines, by comparing its count (106') of date and time to the regulations in place for daylight saving, that daylight saving is coming into force and that timepieces must be advanced by one hour, it generates 3600 pulses are rapidly (602', 706'). Motor driver circuitry (101') then issues a further number of rapid pulses, equal to the number of seconds it took to issue the 3600 pulses, such that the minute and hour hands are sent forward to the positions they would have attained had the regular once-per-second pulse rate been maintained (707', 705'), except that the hour hand is now advanced by one hour.

When motor driver circuitry (101') determines, by comparing its count (106') of date and time to the regulations in place for daylight saving, that daylight saving is ceasing to be in force and that timepieces must be retarded by one hour, it ceases to generate pulses for one hour so that 3600 pulses missing from the regular sequence (603', 708'). The minute and hour hands are now in the position they would have attained had the regular once-per-second pulse rate been maintained (707', 705'), except that the hour hand is now retarded by one hour.

Claims

CLAIMS1. A timepiece, having a pointer, comprising a pulse generator, configured to be in a first state and a second state, wherein the pulse generator operates at a first frequency in the first state and at a second frequency in the second state; an electronic time reference; a pointer position reference; a driving circuit, including a frequency selector, wherein the frequency selector is configured to select the first or second state on comparison of the pointer position to the electronic time reference; and a stepping motor, configured to drive the pointer at the selected frequency.
2. A timepiece as claimed in Claim 1, wherein the pointer is a month pointer, and the pointer position reference indicates the position of the month pointer, wherein the frequency selector is configured to select the first or second state on comparison of the month pointer position to the electronic time reference.
3. A timepiece as claimed in Claim 2, wherein the first frequency is 1Hz and the second frequency is between 60Hz and 70Hz.
4. A timepiece as claimed in Claim 1, wherein the electronic time reference indicates the synodic period, wherein the frequency selector is configured to select the first or second state on comparison of the pointer position to the synodic period.
5. A timepiece as claimed in Claim 4, wherein the frequency selector is configured to compare the pointer position to the synodic period and select the first or second state periodically.
6. A timepiece as claimed in Claim 5, wherein the period between comparisons is between 8 and 12 days.
7. A timepiece as claimed in Claim 1, wherein the pointer is an hour pointer, the pulse generator is further configured to be in a third state, wherein the pulse generator does not operate in the third state, the pointer position reference indicates the position of the hour pointer, and the frequency selector is configured to select the first, second or third state on comparison of the hour pointer position to the electronic time reference.
8. A timepiece as claimed in any one of the preceding claims, wherein the pointer position reference includes a pointer position sensor.
9. A timepiece as claimed in any one of Claims 1 to 7, wherein the pointer position reference is set by the user.
10. A timepiece as claimed in either Claim 8 or Claim 9, wherein the pointer position reference is configured to receive a pulse at the first frequency from the pulse generator, such that the pointer position reference is updated.
11. A method of driving a pointer on timepiece, the timepiece having an electronic time reference, the method comprising the steps of: comparing the position of the pointer to the electronic time reference; selecting a first frequency or a second frequency according to the comparison of the pointer to the electronic time reference; and driving the pointer at the first or second frequency.
12. A method as claimed in Claim 11, wherein the step of selecting a first or a second frequency comprises selecting a first, second or third frequency, wherein the third frequency is 0Hz, according to the comparison of the pointer to the electronic time reference.
13. A timepiece substantially as herein described with reference to and as shown in any combination of the accompanying drawings.
14. A method substantially as herein described with reference to and as shown in any combination of the accompanying drawings.Amendments to the claims have been filed as followsCLAIMS1. A timepiece, having a pointer, comprising a pulse generator, configured to be in a first state and a second state, wherein the pulse generator operates at a first frequency in the first state and at a second frequency in the second state; an electronic time reference; a pointer position reference; a driving circuit, including a frequency selector, wherein the frequency selector is configured to select the first or second state on comparison of the pointer position to the electronic time reference; and a stepping motor, configured to drive the pointer at the selected frequency in a forward direction alone.2. A timepiece as claimed in Claim 1, wherein the pointer is a month pointer, and the pointer position reference indicates the position of the month pointer, wherein the frequency selector is configured to select the first or second state on comparison of the month pointer position to the electronic time reference.3. A timepiece as claimed in Claim 1, wherein the electronic time reference indicates the synodic period, wherein the frequency selector is configured to select the first or * second state on comparison of the pointer position to the synod ic period. * I *** I *IISI* I *.II * * *S 5*SIS * ,4. A timepiece as claimed in Claim 4, wherein the frequency selector is configured to compare the pointer position to the synodic period and select the first or second state periodically.5. A method of driving a pointer on timepiece, the timepiece having an electronic time reference, the method comprising the steps of: comparing the position of the pointer to the electronic time reference; selecting a first fiequency or a second frequency according to the comparison of the pointer to the electronic time reference; and driving the pointer at the first or second frequency in a forward direction alone.6. A timepiece substantially as herein described with reference to and as shown in any combination of the accompanying drawings.7. A method substantially as herein described with reference to and as shown in any combination of the accompanying drawings. S.... I) **SS**S * S S., * S * *S SS*S * S... * S S...S*..*S*S