| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To close a detection hole for making an electric discharge gas flow into a case with a ball, suppress invasion of foreign matters into an inside of the case, guide the electric discharge gas to a sensor passing through a slit between the ball and the case, and detect a tracking sign with high precision. <P>SOLUTION: The detection hole 8 is formed in a front face cover part 2a of the case 2 in wiring accessories such as a power supply receptacle, attachment plug or the like, and electric discharge gas G is introduced passing through the detection hole 8 from outside into the case 2. A positioning groove 13 is formed in the inner wall 10 of the case 2, the sensor 11 formed of a metallic belt plate is fitted into the positioning groove 13 and a locking hole 12 is formed in the sensor 11. A recess part 16 of hemispheric shape is formed on the inner face of the front face cover part 2a so as to be communicated with the detection hole 8, and a portion of the ball 14 fitted into the recess part 16 is locked to the locking hole 12 of the sensor 11. A slit 15 is formed between the ball 14 and the recess part 16, and the electric discharge gas G is guided from the detection hole 8 passing through the slit 15 to the sensor 11. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
