Abstract: A rotary encoder comprises a rotary plate having a plurality of primary slits defined in the rotary plate in a circular row coaxial with the axis of rotation of the rotary plate. The rotary plate also has at least one reference slit defined therein at a position radially of the circular row of the primary slits. A primary photoelectric detector including a source of light and a photo-sensor positioned one above the other with the circular row of the primary slits intervening therebetween is used to detect the passage of the primary slits therethrough while an auxiliary photoelectric detector including a source of light and a photo-sensor positioned one above the other with the path of travel of the reference slit intervening therebetween is used to detect the passage of the reference slit therethrough.

Abstract: A peristaltic pump assembly for pumping a fluid medium from a fluid source through a tubing having a compressible pumping section, which assembly comprises a housing including at least one support wall; a drive shaft journalled substantially loosely to the support wall; a plurality of cam plates eccentrically mounted on the drive shaft in a helical pattern along the drive shaft and rotatable together with the drive shaft for, during a rotation of the drive shaft, driving finger plates sequentially in a direction perpendicular to the drive shaft to cause respective finger tips of the finger plates to engage the pumping section thereby producing a moving zone of occlusion along the pumping section for pumping the fluid medium; and an adjustment mechanism mounted on the support wall for adjustably displacing the drive shaft together with the cam plates and the finger plates in a direction perpendicular thereto.