GB2530548A

GB2530548A - Wristwatch battery state indication and life extension method

Info

Publication number: GB2530548A
Application number: GB1416972.6A
Authority: GB
Inventors: Richard George Hoptroff
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-09-25
Filing date: 2014-09-25
Publication date: 2016-03-30
Anticipated expiration: 2034-09-25
Also published as: GB2530548B; GB201416972D0

Abstract

A timepiece such as a watch indicates when its battery is reaching the end of its life. It does so by stopping the updating and movement of a second indicator, for example a second hand 108, while maintaining the updating and movement of a first indicator, for example a minute hand 107. The hands may be driven by separate motors 102,103.

Description

WRTSTWATCH BATTERY STATE INDICATION

AND LIFE EXTENSION METHOD

This invention is about indicating when a watch battery in an analog watch is reaching the end of its hfe. It does so in a manner that simultaneously prolongs the life of the battery by changing to a lower-power, reduced-function state.

Battery-powered watches have limited power, and the battery need changing from time to time. It would be helpful to inform the user when the battery will soon need changing, so they can get a new battery before the watch has ceased to function. Since the battery voltage starts to drop towards the end of its life, it is possible to detect this state and indicate it to the user.

The state of the art is the PCA2000 timepiece controller from NXP. In normal operation it generates a stepper motor pulse once every second. This is used to move the seconds hand and, via gearing, the minutes and hours hands.

When the battery voltage goes below a threshold level, it instead rapidly issues a series of four pulses once every four seconds. This provides an indication that the battery needs changing while managing to continue to indicate the correct time.

A limitation of the state of the art is that it does nothing to reduce power consumption in the second state.

This invention provides method of simultaneously indicating a low battery and reducing power consumption when the battery needs changing. Accordingly, and with reference to figure 1, the invention is the lollowing method: 1. A timepiece contains a timepiece controller 101, a stepper motor 102 for driving the seconds hand 107 and a separate stepper motor 103 for driving the minutes hand 108, on display 104. (The hours hand 109 might be geared from the minute hand, or driven separately.) Timepiece has a voltage level sensor 105 that detects the voltage of battery 110, and may also have an internal representation of the position 0! the seconds hand in memory 106.

2. In normal operation, timepiece controller 101 issues regular pulses to stepper motor 102 at a rate required for the seconds hand to complete one rotation every minute. Additionally, it issues regular pulses to stepper motor 103 at a rate required for the minutes hand to complete one rotation every hour.

3. When battery voltage level sensor 105 detects that the battery voltage has fallen below a specified level, timepiece controller 101 continues to issue pulses to stepper motor 103. but ceases to issue pulses to stepper motor 102.

4. Optionafly, if timepiece controfier 101 has an internal representation of the position of the seconds hand in memory 106, then it ceases to issue pulses to stepper motor 102 when the seconds hand is at a specific position, for example the 12 o'clock position.

The net effect is that when the battery is low, this is indicated by stopping the seconds hand while continuing to operate the hours and minutes hands. Since pulsing the second hand is the dominant power drain in the system, this drastically reduces power consumption when the battery is low.

A typical embodiment would be a wristwatch controlled by a microcontroller 101 containing an integrated battery voltage detector 105, quartz oseiflator driving circuitry to regulate timing and outputs for driving the stepper motors 102, 103. Once per minute. it measures the battery voltage. If the voltage is 2.SV or higher (assuming 3V lithium batteries), it generates pulses for both stepper motors 102 and 103 during the next minute. If the voltage is lower than 2.5V. it only generates pulses for stepper motor 103 during the next minute. The seconds hand will appear to stop when the battery is low, hut the hours and minutes hands wifl continue to indicate the correct time.

lii an alternate embodiment, microcontroller 101 additionally contains an interna' representation 106 of the position of the seconds hand in memory.

When internal representation 106 indicates that the seconds hand is in the 12 o'clock position, it measures the battery voltage. If the voltage is 2.5V or higher (assuming 3V lithium batteries), it generates pulses for both stepper motors 102 and 103 during the next minute. lithe voltage is lower than 2.5V, it only generates pulses for stepper motor 103 during the next minute. The seconds hand will appear to stop at the 12 o'clock position when the battery is low, but the hours and minutes hands will continue to indicate the correct time.

Claims

CLAIMS1. A timepiece comprising: a controller; a first indicator for indicating first increments of time; and a second indicator for indicating second increments of time which are smaller than the first increments of time, wherein the controller is arranged to cause the first indicator and the second indicator both to he updated over time when the timepiece is in a normal-power mode, and wherein the controller is arranged to cause the first indicator to be updated over time and to cause the second indicator not to be updated over time when the timepiece is in a low-power mode.
2. A timepiece as daimed in claim I induding an anathg face, wherein the indicators are hands for indicating a current time.
3. A timepiece as claimed in claim 1 or 2. wherein the first indicator is a minutes hand for indicating a minutes value, and the second indicator is a seconds hand for indicating a seconds va'ue.
4. A timepiece as claimed in any preceding claim, wherein causing the first indicator to be updated over time includes causing the first indicator to rotate through a first predetermined angle over a period of time, and causing the second indicator to he updated over time includes causing the second indicator to rotate through a second predetermined angle over a period of time.
5. A timepiece as claimed in any preceding claim, wherein the first indicator and the second indicator are mechanical indicators that are updated independently of one another.
6. A timepiece as claimed in any preceding claim, wherein the controller issues pulses to a first stepper motor to cause the first indicator to be updated over time and issues pulses to a second stepper motor to cause the second indicator to he updated over time.
7. A timepiece as claimed in any preceding claim, wherein causing the second indicator not to be updated over time includes causing the second indicator to remain stationary.
8. A timepiece as dainied in any preceding daim, wherein causing the second indicator not to be updated over time includes causing the second indicator to remain stationary for a period of time corresponding to at least one full rotation of the second indicator.
9. A timepiece as claimed in any preceding claim, wherein causing the second indicator not to be updated over time includes not sending pulses to the second stepper motor.
10. A timepiece as claimed in any preceding claim, wherein, while the timepiece is in the low-power mode, the second indicator remains stationary at all times.
11. A timepiece as claimed in any preceding claim, wherein the timepiece includes a battery and a battery voltage level sensor for measuring a voltage across the battery. and wherein the coniroller is arranged to cause the timepiece to operate in the normal-power mode if the battery voltage levd sensor measures a voltage equal to or greater than a threshold voliage and to operate in the low-power mode if the battery voltage level sensor measures a voltage lower than the threshold voltage.
12. A timepiece as claimed in any preceding claim, wherein the controller is arranged to store a representation of the position of the second indicator.
13. A timepiece as claimed in claim 12. wherein the controller is arranged to cause the timepiece to change its mode when the representation of the position of the second indicator matches a predetermined number of the second increments of time.
14. A timepiece as claimed in any preceding claim including a thin! indicator for indicating third increments of time which are larger than the first increments of time.
15. A timepiece as claimed in claim 14, wherein the third indicator is a mechanical indicator which is updated in dependence upon the first indicator, or is updated independently of the first and second indicators.
1. A method for a timepiece controller, comprising the steps of: updating over time both a first indicator for indicating first increments of time and a second indicator for indicating second increments of time, when the timepiece is in a normal-power mode. the second increments of time being smaller than the first increments ol time, and updating the first indicator over time and not updating the second indicator over time, when the timepiece is in a low-power mode.
17. A method as claimed in claim 16, wherein the timepiece includes an analog face and the indicators are hands for indicating a current time.
18. A method as claimed in claim 16 or 17, wherein the first indicator is a minutes hand for indicating a minutes value, and the second indicator is a seconds hand for indicating a seconds va'ue.
19. A method as claimed in claim 16, 17 or 18, wherein updating the first indicator over time includes causing the first indicator to rotate through a first predetermined angle over a period of time. and updating the second indicator over time includes causing the second indicator to rotate through a second predeternrined angle over a period of time.
20. A method as claimed in any of claims 16-19, wherein the first indicator and the second indicator are mechanical indicators, and comprising updating the first indicator and the second indicator independently of one another.
21. A method as claimed in any of claims 16-20, comprising issuing pulses to a first stepper motor to update the first indicator over time and issuing pulses to a second stepper motor to update the second indicator over time.
22. A method as claimed in any of claims 16-21, wherein not updating the second indicator over time includes causing the second indicator to remain stationary.
23. A method as claimed in any of claims 16-22, wherein not updating the second indicator over time includes causing the second indicator to remain stationary for a period of time corresponding to at least one full rotation of the second indicator.
24. A method as claimed in any of claims 16-23, wherein not updating the second indicator over time includes not sending pulses to the second stepper motor.
25. A method as claimed in any of claims 16-24. comprising causing the second indicator to remain stationary at all times, while the timepiece is in the low-power mode.
26. A method as claimed in any of claims 16-25, wherein (lie timepiece includes a battery and a battery voliage level sensor for measuring a voltage across the battery, and comprising causing the timepiece to operate in the noimal-power mode if the battery voltage level sensor measures a voltage equal to or greater than a threshold voltage and to operate in the low-power mode if the battery voltage level sensor measures a voltage lower than the threshold voltage.
27. A method as claimed in any of claims 16-26, comprising storing a representation of the position of the second indicator.
28. A method as claimed in claim 27, comprising causing the timepiece to change its mode when the representation of the position of the second indicator matches a predetermined number of the second increments of time.
29. A method as claimed in any of claims 16-28, wherein the timepiece includes a third indicator for indicating third increments of time which are larger than the first increments of time.
30. A method as claimed in claim 29. wherein the third indicator is a mechanical indicator, and comprising updating the third indicator in dependence upon the first indicator or independently of the first and second indicators.
31. A computer program product directly loadable into the internal memory of a digital computer, comprising software code portions for performing the steps of claims 16-30 when said product is run on a computer.