| 摘要 |
In a device such as a spectrophotometer with an associated chart recorder in which the speed ratio between a first displaceable member and a second displaceable member may be selectively changed within a predetermined range of speed ratios, in a first embodiment of invention which is mechanical in nature, a number of gear trains in constant mesh with each other are provided to obtain the different speed ratios. Each of the gear trains has associated therewith a rotary disc with circumferentially even spaced apertures, the gear train obtaining an input from the first displaceable member by means of arms rotatable concentric with the discs, the arms carrying a pin adapted to enter into positive engagement with any one aperture, the number apertures depending on the scale served by the associated gear train. In a second, electrical embodiment equivalent operation is obtained by maintaining counts in counters of the position where the second displaceable member would be for each of the given scales along with maintaining a count of the actual position with comparator means used to bring the actual count into correspondence with the desired count when a scale change takes place. |
