| 摘要 |
PURPOSE:To enable inspection of the propriety in a state of joint of a mask structure in contact with none of a shadow grill, by checking displacement of the shadow grill and that of a vibrator in a non-contact manner. CONSTITUTION:A mask structure 3 with all of component members welded securely is mounted on a vibration table 15 and vibration is applied with a vibrating machine 14 in the direction the arrow A. When at least one defective part exists among a joint between a shadow grill 7 and a frame 8, that between the frame 8 and a bimetal 11 and that between the bimetal 11 and a spring 10, a vibrating force from a retaining pin 16 fails to be transmitted exactly to the shadow grill 7 and instead, the joints are vibrated by a vibrating force transmitted through other joints 30, which causes an overlapping of harmonics or deviation in the phase of vibration depending on a relation with a natural frequency. As a result, an average output of an analog adder 19 increases. Thus, the average output is compared with a preset threshold by a judgement display device 20, thereby enabling judgement on the property of the state of joint.
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