Optical position detection of a timepiece crown stem

Patent metadata

Field	Value
Publication number	US-2016116306-A1
Application number	US-201514923700-A
Country	US
Kind code	A1
Filing date	Oct 27, 2015
Priority date	Oct 28, 2014
Publication date	Apr 28, 2016
Grant date	—

Abstract

A method of detecting a movement of a timepiece setting stem arranged to be moved axially along and/or rotated about its longitudinal axis. The method includes a light source illuminating a portion of the setting stem; a light detector receiving a reflected or diffracted light pattern from the setting stem; a processor forming a first pixel pattern representative of the reflected light pattern at a first time instant; the processor forming a second pixel pattern representative of the reflected light pattern at a second, later time instant; and determining that the setting stem has been moved, if the second pixel pattern is different or shifted with respect to the first pixel pattern.

First claim

1 . A method of detecting a movement of a timepiece setting stem arranged to be moved axially along and/or rotated about its longitudinal axis, the method comprising:
a light source illuminating a portion of the setting stem; an optical sensor receiving a reflected or diffracted light beam from the setting stem; a processor forming a first pixel pattern representative of the reflected light beam at a first time instant; the processor forming a second pixel pattern representative of the reflected light beam at a second, later time instant; and determining that the crown has been moved if the second pixel pattern is shifted with respect to the first pixel pattern.

2 . The method according to claim 1 , wherein the detected movement is angular movement of the setting stem.

3 . The method according to claim 1 , further comprising determining the amount of movement of the setting stem by determining how much the second pixel pattern is shifted with respect to the first pixel pattern.

4 . The method according to claim 1 , further comprising incrementing a register value by one if the second pixel pattern is shifted in a first direction by one pixel with respect to the first pixel pattern, and decrementing the register value by one if the second pixel pattern is shifted in a second direction, opposite to the first direction, by one pixel with respect to the first pixel pattern.

5 . The method according to claim 4 , wherein the amount of angular movement of the setting stem at any time instant is given by the register value.

6 . The method according to claim 1 , further comprising detecting galvanically the axial movement of the setting stem.

7 . The method according to claim 6 , wherein the galvanic detection comprises encoding a portion of the setting stem with an encoding pattern having varying electrical conductivity, wherein the encoded pattern is a binary pattern comprising encoded rings and contacting the encoding pattern with conducting sensor elements to determine the encoding pattern at a given axial position of the setting stem.

8 . The method according to claim 1 , wherein a detection resolution of more than 100 angular positions for the setting stem can be defined.

9 . The method according to claim 1 , wherein the angle of incidence of the reflected light when reaching the optical sensor is between +10 and −10 degrees.

10 . The method according to claim 1 , further comprising receiving a movement detection activation signal to activate the method.

11 . The method according to claim 10 , wherein the movement detection activation signal is received when any type of movement of the setting stem is detected.

12 . The method according to claim 1 , further comprising deactivating the method when the setting stem has been detected to be immobile for a given time period.

13 . The method according to claim 1 , wherein the first and second pixel patterns are formed at least 100 times per second.

14 . A sensor arrangement for detecting a movement of a timepiece setting stem, the arrangement comprising:
a timepiece setting stem arranged to be moved axially and/or rotated about its longitudinal axis; a light source for illuminating a portion of the setting stem; an optical sensor for receiving a reflected or diffracted light beam from the setting stem; and a processor for processing the reflected light beam, wherein the processor is configured to form a pixel pattern representative of the reflected light pattern and to compare a first pixel pattern obtained at a first time instant and a second pixel pattern obtained at a second, later time instant, and if the second pixel pattern is shifted with respect to the first pixel pattern, then the processor is arranged to determine that the setting stem has been moved.

15 . A timepiece comprising the sensor arrangement according to claim 14 .

Assignees

• Swatch Group Res & Dev Ltd

Inventors

• Ferri Yvan
• Balmer Raphael
• Schmutz Damien
• Lagorgette Pascal

Classifications

• G01D5/347

  using displacement encoding scales · CPC title

• G04C3/001 Primary

  Electromechanical switches for setting or display · CPC title

• G04B27/002 Primary

  The setting apparatus being crown shaped (G04B27/02 takes precedence) · CPC title

• G01D5/30 Primary

  the beams of light being detected by photocells · CPC title

• G01D5/252

  a combination of conductors or channels · CPC title