MECHANISM FOR CAUSING EARLY CRACK

摘要

[PROBLEMS] The provision of a mechanism for causing a very tiny early crack at an accurate location with good reproducibility. [MEANS FOR SOLVING PROBLEMS] The mechanism (30) to cause an early crack has a cutting blade unit (1) with a cutting blade (17) at a tip thereof in opposition to a substrate (K), the cutting blade unit (1) being supported for linear motion relatively to the substrate in a direction (Y) along a slated line (J) to cause the crack while for rotary motion around a horizontal axis (15) intersecting a direction of the relative linear motion. There is provided a first retention means (5) to keep the cutting blade unit against rotation around the horizontal axis in a phase where the cutting blade is held at a location (P1) to get the early crack causing, but releasing the cutting unit from the retention by a resistant force that occurs when the cutting blade in the course of the linear motion comes into collision against a beginning end of the slated line to cause the crack on the substrate. Further, there is provided a second retention means (4) to get the cutting blade unit after released from the restraint by the first retention means to turn around the horizontal axis while keeping the cutting blade at a retracted position (P2).