| 摘要 |
PROBLEM TO BE SOLVED: To ground a circuit board on a housing with reliability without increasing the number of screws, and to maintain the constant performance. SOLUTION: A circuit board 2 is placed on the bottom plate of an outer housing 1 and is fixed by an inner housing 3. The inner housing 3 is formed in the shape of a box with a lower side open and is fixed to the outer housing 1 through the circuit board 2 with a screw 4. Namely, the inner housing 3 fixes the circuit board 2 by fastening the angles 3c in three corners to the bottom plate of the outer housing 1 with the screw 4, and pressing the side wall of the inner housing 2 to the circuit board 2 to fix the circuit board 2. The other angle 3d of the inner housing 3 is provided with a protrusion 11 on an extremity in contact with the circuit board 2. When the circuit board 2 and the inner housing 3 are fixed by the screw 4, the protrusion 11 is pressed against the circuit board 2 by an enough force. Also, a protrusion 12 in contact with the lower ground surface of the circuit board is provided in one corner corresponding to the angle on the bottom plate of the outer housing 1 to ensure the ground connection.
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