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.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in more detail below with reference to a few figures. Shown are:

FIG. 1 is a block diagram for illustrating the movement recording in a sewing machine using a self-coupling laser Doppler interferometer,

FIG. 2 is a side view of a partially cut-away hook with bottom thread bobbin set therein,

FIG. 3 is a detail view of a sewing machine in the area of the stitch forming device with sensors integrated into the needle plate,

FIG. 4 is a view of a sewing foot with integrated detection device.

Claims

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), anddetermining 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.