| 摘要 |
PROBLEM TO BE SOLVED: To improve the detecting precision for a remaining thread amount by providing a detecting sensitivity regulating circuit which regulates the detecting sensitivity of a detector to detect the remaining thread amount of a bobbin in a bobbin case, and at the same time, providing a detecting sensitivity regulating circuit which regulates the detecting sensitivity of a lint detector to detect lint in the vicinity of the bobbin. SOLUTION: When a remaining thread amount is detected, on the outside of a shuttle race body 10 arranged in a sewing machine frame 1, a light source LD1 by a light-emitting diode, or the like, and a photo-detector PT1 by a photo-transistor, or the like, are provided in such a manner that an optical axis from the light source LD1 to the photo-detector PT1 may be orthogonal with a hook shaft 18, i.e., the axial section of a bobbin 12. Also, when lint is detected, a photo-interrupter PI using the same optical element is arranged under the bobbin 12. Then, for the sensitivity regulation of a remaining thread amount detecting means and a lint detecting means, variable resistors VR1 and VR3 are provided. Then, the result that the sensitivity regulation of the remaining thread amount detecting means and the lint detecting means has been correctly performed is displayed to a user by the lighting up of light- emitting diodes LD3 and LD4.
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