Optical unit for image projection and tool incorporating same

摘要

An optical unit (52) for projecting an image (54) including the first and second locating lines (72,74) for substantially eliminating the introduction of visual parallax error. In a preferred form, the optical unit (52) is incorporated into a machine (10) for performing a forming operation on a workpiece (30) and is operative to project an image (54) of a portion of a scale (50) to a position easily read by the user during machine operation. The optical unit (52) includes a prism portion (56) having a first side (64) disposed adjacent the scale (50), a second side (66) at an angle a to the first side (64) for reflecting the image (54) and a third side (68) through which the projected image (54) may be viewed. The first locating line (72) is disposed on the first side (64) and the second locating line (74) is disposed on the third side (68) such that visual alignment eliminates the introduction of visual parallax error associated with reading a scale (50).