Wearable object such as a timepiece including means for triggering an electronic control function

A portable object comprising:

• (a) a dial covered by a glass;
• (b) an electronic control circuit for at least one time function or non-time related function, wherein the electronic control circuit is enclosed by the portable object;
• and
• (c) at least one light source and an associated light sensor, wherein the at least one light source and associated light sensor are arranged on the dial, wherein the light sensor defines an acceptance cone, wherein the geometry of the acceptance cone defines a limit between light that falls into the cone and is converted into a current by the light sensor, and light that passes outside the limit of the acceptance cone,
• wherein the light source is disposed to emit a light beam through the glass, wherein the light beam is at least partially reflected towards the light sensor when it is intercepted by a user's finger placed on a spot of defined dimension on the glass of the portable object,
• wherein the light sensor is connected to supply the electronic control circuit with an electric signal that activates a function when the light sensor directly detects light that is produced by the light source and directly reflected by the user's finger into the acceptance cone,
• wherein the light source is disposed to emit collimated light forming the spot of defined dimensions on the glass, and wherein the spot defines a place on the glass for the user to place a finger.