GB2501137A

GB2501137A - Non-linear pointer movement in timepieces

Info

Publication number: GB2501137A
Application number: GB1214194.1A
Authority: GB
Inventors: Richard George Hoptroff
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-08-08
Filing date: 2012-08-08
Publication date: 2013-10-16
Anticipated expiration: 2032-08-08
Also published as: GB2501137B; GB201214194D0

Abstract

An electronic device, preferably a timepiece, uses as pointers to indicate numerical values on graduated scales, in particular, where either the graduated scale is not a circle, or an arc of a circle, or the axis of rotation of the pointer is not concentric with the graduated scale. The angles between consecutive markings on the scale may not be the same so a target angular position corresponding to the target marking is calculated and the pointer driven accordingly.

Description

NONLINEAR METHOD FOR ROTATING POINTERS

iN ELECTRONIC DEVICES S This invention relates to the use of rotating mechanical display elements, such as pointers, to indicate numerical values on graduated scales in electronic devices. In particular, it relates to situations where either the graduated scale is not a circle, or an arc of a circle, or the axis of rotation of the pointer is not concentric with the graduated scale.

Analogue timepieces and metering devices traditionally use display elements that rotate in proportion to the quantity they are attempting to convey. For example, as time passes, a minute hand of a clock or watch rotates by 6° per minute; the hour hand by 300 per hour. This arrangement leads to a pleasing, evenly-spaced arrangement of graduations on the scale, provided the scale is circular and the axis of rotation of the pointer is concentric with it (figure 1).

There is commercial pressure, however, to vary designs in search of uniqueness. Therefore the state of the art is arguably to use a scale that is not circular (figure 2), or the axis of rotation of the pointer is not concentric with the scale (figure 3).

A limitation of these states of the art is the loss of linearity between the rotation of the pointer and the distance progressed along the graduated scale.

For example, in figure 4, despite angles 401' and 402' being equal, the distance 403' along the graduated scale between hours 8 and 9 is appreciably longer than the distance 404' between hours 9 and 10. Likewise, in figure 5, between hours AB (501') relative to CD (502'). The loss of linearity is a visual distortion to the commonly accepted visual interpretation and can be hard to accept.

Current practice, as embodied by wristwatch designs such as the Cartier Crash Watch (figure 10), invests much creative energy into distracting the eye from the distortion. However, such styling is limited in the number of degrees of variation, and also the extent to which the public is willing to accept abnormal visual displays of quantitative information. The Cartier Crash Watch, for example, is undeniably beautiful, but it is quite hard to read the time.

Rather than attempting to change the visual appearance alone, this invention aims to preserve linearity between the rotation of the pointer and the distance progressed around the graduated scale. Specifically, it provides mechanisms that vary the degree of rotation of the pointer relative to the quantity being indicated; it is the pointer turn that is nonlinear, rather than the visual appearance.

Accordingly, and with reference to figures 6 and 7, the invention is the following device: I. Electronic device comprising motor driver circuitry 601, memory store 602, pulse counter 603, stepper motor 604 and mechanical display element such as a pointer 605 whose rotational position is measured against a scale 606. The markings on the scale are such that equally spaced graduations along the scale (607, 608, 609) do not correspond to equal angles of rotation of the display element (610,611).

2. From time to time, motor driver circuitry determines, 70i, a quantity to be displayed and stores this as a numerical value in memory 602.

3. Motor driver circuitry computes, 703, the angular position required to move the pointer a distance along the scale which is in proportion to the numerical value stored in memory.

4. Motor drive circuitry compares the required angular position with the cluTent position, as stored by a stepper motor pulse counter. If they are not equal, the circuitry executes the number of motor pu'ses for them to be equal.

One embodiment of the invention is the following device, with reference to figure 8. A temperature indicator has a rotating pointer 801 and a linear scale 802. The graduations 803 on the scale are equidistant along the scale, but far from equal angles subtended from the axis of rotation of the pointer. At the extremes of the scale, a variation of 10°C is a 6° angle (804), whereas at the centre it is 15.75° (805).

From time to time, the temperature is measured and stored in memory. The value stored in memory is used as the index value in a look-up table in which the optimum pointer angle for each temperature value has been pre-calculated.

The looked-up pointer angle is compared to the current stepper motor position and, if they are different, the appropriate number of stepper motor pulses is issued.

A second embodiment of the invention is the following device, with reference to figure 9. Seconds dial has a rotating pointer 901 and a pentagular scale 902.

The graduations 903 on the scale are equidistant along the scale, but unequal in terms of angle subtended from the axis of rotation of the pointer. (If they were, they would be closer spaced at the middles of the edges than at the vertices, as in figure 2.) Typically, the stepper motor used to drive such a device would have sixty equal steps per rotation. It will not therefore be possible to implement the first embodiment, i.e. moving the pointer once per second so it aligns accurately with its corresponding graduation. Instead, the time interval between steps is modulated such that the pointer takes up its new angular position at the moment in time when that position would be the colTect value. The interval between steps will be less than a second when the pointer is pointing towards the middle of an edge, and more than a second when pointing towards a vertex.

Claims

Cl AIMS 1. A method for driving an electronic device, the electronic device comprising a pointer and a scale including a plurality of markings. wherein the pointer is configured to rotate a first angle between a first angular position and a second angular position corresponding to a first and second marking respectively, and to rotate a second angle between the second angular position and a third angular position corresponding to the second and a third marking respectively, the first and second ang'es being different, the method comprising the steps of: determining a target marking to be indicated by the pointer; cakulating a target ang&ar position of the pointer colTespondrng to the target marking; and dnving the pointer to the target angular position.
2. A method as claimed in Claim i, wherein the electronic device includes a stepper motor for driving the pointer at regular time intervals, the method further comprising the steps of: cakulating a number of pulses for driving the pointer to the target angular position; and dnving the stepper motor by the number of pulses such that the pointer moves to the target angular position.
3. A method as claimed in Claim i, wherein the electronic device includes a stepper motor for driving the pointer by a regular number of pulses, the method further comprising the steps of: cakulating a target time for driving the pointer to the target angular position; and driving the stepper motor at the target time such that the pointer moves to the target angular position.
4. A method as claimed in any one of the preceding claims, wherein the electronic device is a timepiece.
5. A method substantially as herein described with reference to and as shown in accompanying Figures 6 to 9.
6. An electronic device having a pointer and a scale including a plurality of markings, wherein the pointer is configured to rotate a first angle between a first position and a second position corresponding to a first and second marking respectively, and to rotate a second angle between the secondSposition and a third position corresponding to the second and a third marking respectively, the first and second angles being different, the electronic device comprising a computational module, for calculating a target angular position of the pointer corresponding to a target marking; and driving circuitry, for driving the pointer to the target angu'ar position.
7. An electronic device as claimed in Claim 6, wherein the computational module is also for calculating a number of pulses for driving the pointer to the target angular position, and the driving circuitry comprises a stepper motor for driving the pointer at regular time intervals by the number of pulses.
8. An electronic device as claimed in Claim 6, wherein the computational rnodue is also for calculating a target time for driving the pointer to the target angular position. and the driving circuitry comprises a stepper motor for driving the pointer by a regular number of pulses at the target time.
9. An electronic device as claimed in any one of Claims 6 to 8. being a timepiece.
10. An electronic device substantially as herein described with reference to and as shown in accompanying Figures 6 to 9.Amendments to the claims have been filed as follows.CLAIMS1. A method for driving an electronic device, the electronic device comprising a pointer, a scale including a plurality of markings, wherein the pointer is configured to rotate a first angle between a first angular position and a second angular position corresponding to a first and second marking respectively, and to rotate a second angle between the second angular position and a third angular position corresponding to the second and a third marking respectively, the first and second angles being different, and a stepper motor for driving the pointer by a regular number of pulses, the method comprising the steps of: determining a target marking to be indicated by the pointer; calculating a target time for driving the pointer to the target angular 1 5 position of the pointer corresponding to the target marking; and driving the stepper motor at the target time such that the pointer moves to the target angular position.2. A method as claimed in Claim 1, wherein the electronic device is a C".! 20 timepiece.*:"! 3. A method substantially as herein described with reference to and as shown in accompanying Figures 6 to 9.* 25 4. An electronic device having a pointer, a scale including a plurality of matkings, wherein the pointer is configured to rotate a first angle between a first position and a second position corresponding to a first and second marking respectively, and to rotate a second angle between the second : * position and a third position corresponding to the second and a third marking * :* : 30 respectively, the first and second angles being different, the electronic device comprising a computational module, for calculating a target time for driving the pointer to the target angular position, corresponding to a target marking; and driving circuitry, comprising a stepper motor for driving the pointer by a regular number of pulses at the target time for driving the pointer to the target angular position.5. An electronic device as claimed in Claim 4, being a timepiece.6. An electronic device substantially as herein described with reference to and as shown in accompanying Figures 6 to 9.According to a first and second aspect of the invention, there is provided a method and an electronic device as claimed in Claims 1 and 4 respectively.Accordingly, and with reference to figures 6 and 7, the invention may be the following device: 1. Electronic device comprising motor driver circuitry 601, memory store 602, pulse counter 603, stepper motor 604 and mechanical display element such as a pointer 605 whose rotational position is measured against a scale 606. The markings on the scale are such that equally spaced graduations along the scale (607, 608, 609) do not correspond to equal angles of rotation of the display element (610, 61!).2. From time to time, motor driver circuitry determines, 701, a quantity to be displayed and stores this as a numerical value in memory 602.3. Motor driver circuitry computes, 703, the angular position required to move the pointer a distance along the scale which is in proportion to the numerical value stored in memory.". : 4. Motor drive circuitry compares the required angular position with the * currcnt position, as stored by a stepper motor pulse counter. If they are * * not equal, the circuitry executes the number of motor pulses for them to be equal.* S One embodiment of the invention is the following device, with reference to figure 8. A temperature indicator has a rotating pointer 80! and a linear scale 802. The graduations 803 on the scale are equidistant along the scale, but far * from equal angles subtended from the axis of rotation of the pointer. At the : d** extremes of the scale, a variation of 10°C is a 6° angle (804), whereas at the ". : centre it is 15.75° (805). * S.From time to time, the temperature is measured and stored in memory. The value stored in memory is used as the index value in a look-up table in which the optimum pointer angle for each temperature value has been pre-calculated.The looked-up pointer angle is compared to the current stepper motor position and, if they are different, the appropriate number of stepper motor pulses is issued.A second embodiment of the invention is the following device, with reference to figure 9. Seconds dial has a rotating pointer 901 and a pentagular scale 902.The graduations 903 on the scale are equidistant along the scale, but unequal in terms of angle subtended from the axis of rotation of the pointer. (If they were, they would be closer spaced at the middles of the edges than at the vertices, as in figure 2.) Typically, the stepper.motor used to drive such a device would have sixty equal steps per rotation. It will not therefore be possible to implement the first embodiment, i.e. moving the pointer once per second so it aligns accurately with its corresponding graduation. Instead, the