| 摘要 |
A holder 1 is formed by laminating support members 3, 4 and 5 and passing holder holes 2 through them. A pair of needle members 9 and 10 are provided on either end of the coil spring 8. Each of the needle members 9 on one side is prevented from coming off by one of the support members 3. The length L between the flange portion 9b received in a large diameter hole 2b of the holder hole and the tip of the needle portion 10a is made substantially equal to the depth D of the large diameter hole 2b of the holder 1. Because the coil springs are thus placed substantially in an unstressed state, when at least one of the needle members is prevented from projecting from a corresponding end of the holder hole, the part that prevents the needle members from coming off is not subjected to a compressive load of the coil springs. Therefore, even when the holder is given with a small thickness, warping or deflecting of the holder can be avoided, and material having a small coefficient of thermal expansion such as ceramic material can be used for the holder.
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