| 摘要 |
<p>The invention relates to a tool positioning aid for positioning a tool, such as a drilling rig. Image superimposing means (29) are provided for superimposing a virtual image ( 101) of a drill position indicating pattern (56) onto a blast face (14). The image superimposing means (29) includes a first patterned screen (54), having a drill position indicating pattern (56) formed thereon. A second beam splitter screen (50) is interposed in the line of sight between the working end (28) of the drill (22) and an operator (32) thereof. Projection means, which includes a light source (70) and a lens arrangement (62) are provided for projecting an image (101) of the first screen (54) onto the second screen (50) such that the drill position indicating pattern (56) appears to be superimposed on the blast face (14) when viewed by the operator (32) along the line of sight (30). An alignment mechanism (38,40,42,44) is used to align the virtual image (101) with a reference mark (20) on the blast face (14). The invention extends to a method of positioning a tool on a workpiece. <IMAGE></p> |
