Sewing or embroidery machine
AssigneeFritz Gegauf Aktiengesellschaft Bernina-Nahmaschinenfabrik
InventorGerard Durville
Life of this patent
Estimating the term…
Abstract
Monitoring of the rotation speed and stationary state of the lower thread bobbin in a sewing machine is performed using a light emitter and two reflected light receivers. The light rays reflected at the surface of the front flange of the bobbin are incident in a sequence which differs in time on the reflected light receivers. These data are evaluated by a computer, which can be the computer of the sewing machine, and are used to stop the machine or the sewing process before the thread end leaves the stitch plate of the sewing machine. It can also be determined from the observed direction of rotation of the bobbin whether the bobbin is correctly placed in the bobbin housing. From the relationship of kind of stitch, stitch speed, and bobbin rotation speed, the bobbin thread supply can also be calculated.
Claims6
A sewing or embroidery machine (1) with a hook (15) driveable by a drive motor and with a lower thread bobbin (17) rotatably mounted therein for receiving a lower thread supply, the bobbin having a hollow cylindrical arbor and annular flanges (21, 22) set on the arbor ends, of which at least one of the flanges (21) having perforations (19) therethrough, or is provided with non-reflecting markings, a light source (35) and two photosensors (43′, 43″) for receiving the light rays (37) emitted from the light source (35) at two spaced-apart locations, and a calculating and control unit for processing signals supplied by the photosensors (43′, 43″), wherein the light source (35) and the two photosensors (43′, 43″) are arranged axially spaced in front of the flange (21) with the perforations (19) or markings;
- and the light rays (37) are directed at an acute angle onto a front surface (39) of the flange (21).
Dependencies are inferred from the claim text.