| 摘要 |
PURPOSE:To always obtain a clear projection image by pressing an eyepiece frame against an attachment by an exciting means at the loading the attachment to an eyepiece part to move the eyepiece frame to a prescribed position in a diopter adjusting range. CONSTITUTION:At the loading of the attachment 14 to a mount 12, a guide pin 13 is led into a guide groove 15 and the attachment 14 is engaged with the mount 12 and rotated, so that an engaging chip 20a on the head of the eyepiece frame 8 is led into an engaging groove 20b of the attachment 14 and an eyepiece 9 is moved to a prescribed position in the diopter adjusting range even if an eyepiece frame 8 is located on any position in the diopter adjusting range. In this state, since the engaging chip 20a is always pressed to the lower wall of the engaging groove 20b by a steel ball 17 excited with a coil panel, the eyepiece is always moved to a fixed position with no error, and an object is always clearly formed an image on a projection plane.
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