| 摘要 |
A microtome, in particular an ultramicrotome has a drive control system, by means of which the movement of the specimen arm, relative to the knife, is subdivided into a comparatively slow cutting movement and a more rapid return movement. The drive-control system gradually decelerates the specimen arm at the transition from the comparatively rapid return movement to the slower cutting movement, so that a jerk, which would generate mechanical vibrations in the drive system, is avoided and the specimen arm is smoothly decelerated from the comparatively high speed, to the lower speed. For this purpose, the drive-control system incorporates an electronic control module, by means of which the control voltage for the drive motor is linearly varied between the comparatively high control voltage value and the lower control voltage value, the rate of rise or, as the case may be, the rate of fall of the voltage being adjusted in a manner such that the specimen arm operates without transitional vibrations. For this purpose, the electronic control module incorporates a constant-current source, and a capacitor which is to be charged by this constant- current source, or which is to be discharged, as the case may be. |
