| 摘要 |
PURPOSE:To easily open a lid of a shutter by a weak force by moving and energizing the shutter from its open lid position to closed lid position by a combined force of more than two springs, each having a low spring constant. CONSTITUTION:More than two springs 19 and 20, each having a low spring constant are disposed in a serial state, and when the shutter 7 is moved energizing to the closed lid position by the combined force of the springs, this combined spring stress can promote a positioning force for the closed lid position of the shutter 7 up to a prescribed value. Moreover, the combined force of >=two springs 19 and 20 disposed in the serial state is able to give a moving force to the shutter 7 for the closed lid position covering the whole area of a big opening and closing stroke. By this method, even if the opening and closing stroke of the shutter 7 is big, a stress difference of the springs between the commencing state of opening the shutter 7 and the ending state of opening the shutter 7 is reduced.
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