The anode of an arc lamp is supported on an arm. When the arc lamp fails, motion of the arm detects the failure and turns the current off of the arc lamp. In addition, after failure of the lamp, the arm limits motion of the anode so that it does not strike adjacent structure....http://www.google.de/patents/US4598348?utm_source=gb-gplus-sharePatent US4598348 - Arc lamp support system
