| 摘要 |
The bridge is reinforced by a metal plate which reinforces the upper and lower part of the frame. This plate can be arranged to be detachable. The frame can be partly or completely separated along the line of the bridge and the hinges. The reinforcing plate joins the two halves at the bridge and a screw which passes through three components is used for the joining. The frame can be made of plastic such as celluloid or of a metal such as aluminium. |
