Device and method for sensing a change of yarn feed bobbin

A device for sensing the change of feed bobbin for a yarn fed to a textile machine and originating from a first bobbin or a second bobbin connected together in head-tail manner, comprising

• a support body defining a passage section for a yarn,
• yarn sensing means comprising at least one first sensor and one second sensor which respectively define a first sensing zone and a second sensing zone positioned at said passage section,
• a control unit operatively associated with said sensing means to control the feed of said yarn to the textile machine,
• said sensing means arranged to generate corresponding first and second presence signals when the yarn unwound from the first bobbin or from the second bobbin passes through said first sensing zone or second sensing zone,
• said control unit arranged to receive said first and/or second presence signal as input and also arranged to generate at least one output signal indicating whether said yarn originates from said first bobbin or from said second bobbin on the basis of said first or second presence signal;
• said first sensor and second sensor comprising respective light emitter elements to illuminate said yarn in presence to said first sensor or said second sensor, and at least one receiver element;
• said light emitter elements being activatable in turn to illuminate said yarn exclusively in presence to said first sensor or said second sensor to generate a succession of first and second presence signals;
• wherein said control unit generates a change-over signal representative of the change in origin of said yarn from said first bobbin to said second bobbin when said first presence signals terminate and said second presence signals commence.