| 摘要 |
A demonstration device 10 for showing the required size of lenses for frames 44 comprises a base plate 12with two horizontal guide slots 16 and a vertical guide slot 18. Two carriages 24, which in each case carry a circular template 28, are movable in the horizontal guide slots 16. The diameter of templates 28 correspond to the diameter of commercial blanks for eyeglass lenses. The distance between the centers of the templates 28 can be adjusted to the distance between the wearer's pupils by moving the carriages 24. A slide 32 is movable in the vertical guide slot 18. It has a leading edge 38 which supports the lower edge of the frame 44. The slide 32 is adjusted to correspond to the distance between the wearer's pupils and the lower edge of the frame 44. By overlapping between the templates 28 and the rims 48 of the frame 44, it is possible to see whether regular lenses or oversized lenses must be used.
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