Sewing machine and method for detecting movements in sewing machines

Abstract

A sewing machine having a detection device for movements of objects ( 13 ) is provided. Here, a coherent light beam ( 11 ) is emitted, scattered on the object ( 13 ), and returns to form an interference with the emitted light. For movements of the object ( 13 ), a frequency shift of the scattered light is produced due to the Doppler effect, which can be detected and evaluated in the form of intensity fluctuations.

1 . Sewing machine with a device for detecting movements, comprising at least one light source ( 1 ) that emits coherent light, an interference detector allocated to the light source ( 1 ), the interference detector is constructed for detecting a measurement parameter that characterizes an interference between reflected light from the light source ( 1 ) that is scattered by an object ( 13 ) to be detected and the light emitted from the light source ( 1 ). 
   
   
       2 . Sewing machine according to  claim 1 , wherein the light source ( 1 ) comprises a laser with a resonator ( 3 ), an optical system ( 9 ) is provided for influencing a transmission beam ( 11 ) and the optical system ( 9 ) is simultaneously constructed for collecting and re-coupling the reflected light of the light source ( 1 ) that is scattered by the object ( 13 ) into the resonator ( 3 ), and the interference is created in the resonator ( 3 ). 
   
   
       3 . Sewing machine according to  claim 2 , wherein the device comprises several light sources ( 1 ), the arrangement of the light sources ( 1 ) and a construction of the optical system ( 9 ) are such that transmission beams ( 11 ) of the light sources ( 1 ) intersect a surface of the object at different angles of incidence (α). 
   
   
       4 . Sewing machine according to  claim 1 , wherein the device for detecting movements is integrated at least partially into a sewing foot ( 41 ) or a sewing foot sole ( 42 ). 
   
   
       5 . Sewing machine according to  claim 1 , wherein the device for detecting movements is arranged at least partially in a hook housing ( 29 ) inside or underneath a needle plate ( 27 ) or on or underneath a sewing machine head ( 39 ). 
   
   
       6 . Sewing machine according to  claim 1 , wherein the device for detecting movements comprises a programmable or configurable evaluation unit. 
   
   
       7 . Sewing machine according to  claim 1 , wherein the device comprises a memory for storing information about the objects ( 13 ) to be detected and/or movements of the objects ( 13 ) and/or an arrangement of sensors. 
   
   
       8 . Method for detecting movements in a sewing machine, comprising:
 using one or more light sources ( 1 ) to emit coherent light in a direction of an object ( 13 ) to be detected,   detecting scattered light of these light sources ( 1 ) that is scattered by the object which then forms an interference with the light of the respective light source ( 1 ), wherein, when the object ( 13 ) moves, the scattered light undergoes a frequency shift that is dependent on the object movement due to the Doppler effect, and for each of the light sources ( 1 ), and   determining and evaluating a measurement parameter, which changes as a function of the interfering light.   
   
   
       9 . Method according to  claim 8 , wherein processing of the detected measurement parameter or the detected measurement parameters is performed using stored information on the object ( 13 ) to be detected and/or its degrees of freedom in terms of movement and/or using information obtained from other known measurement parameters. 
   
   
       10 . Method according to  claim 8 , further comprising the determining and evaluating step including determining velocities and/or movement directions and/or absolute or relative orientation or position vectors from the measurement parameter or parameters.