Part holding head assembly for chip mounting device

A part holding head assembly of a part mounting device comprising:

• a rotary head;
• a spindle configured to rotate in a first direction T with respect to a central axis of the spindle and configured to move in a second direction Z substantially parallel with an extending direction of the central axis of the spindle;
• a nozzle provided at a first end of the spindle;
• a raising part configured to move the spindle in the second direction Z;
• and
• a contact detecting sensor configured to sense the nozzle contacting a part or the part held by the nozzle contacting a substrate and configured to generate a contact sensing signal according to the sensing,
• wherein the contact detecting sensor comprises:
• a light-emitting unit configured to emit light toward an outer reflective surface of the nozzle;
• a light-receiving unit configured to receive reflected light reflected from the outer reflective surface;
• and
• a sensor unit configured to measure a received amount of the reflected light and to generate the contact sensing signal in response to the received amount of the reflected light decreases to be lower than or equal to a threshold value, and
• wherein the contact detecting sensor is configured to set the threshold value based on an amount of the reflected light received by the light receiving unit after completion of a T-direction rotation operation of the spindle before the nozzle contacts the part.