| 摘要 |
PURPOSE:To make it possible to detect an abnormal shot by a method wherein a detecting device, which detects the development of the positional shifting of at least one plunger relatively from the positions of other plungers at the movements of a plurality of the plungers. CONSTITUTION:When no abnormality occurs in the movements of plungers 1, (n) plungers 1 move all alike, resulting in bringing the relative positions of the light transmitting slits 9 of the respective plungers 1 also in line with one another. At this time, the respective light transmitting slits 9 of the (n) plungers 1 lie on one straight line at all times, resulting in letting a linear optical sensor 8 to detect the light emitted from a linear light source 9 at all times. But, if catching and the like develop for some cause or other, the movement of the troubled plunger delays, resulting in bringing one or more of the light transmitting slits 9 out of the straight line. Accordingly, the light emitted from the linear light source 7 is interrupted, resulting in realizing an instant, in which no light reaches the linear light sensor 8. When the light is interrupted, the linear optical sensor 8 issues no output. As a result, abnormal shot can be informed on the basis of no output. |
