Patent ID: 8177951

Claim:
An electrophoresis apparatus comprising: one or more capillaries to be filled with an electrophoretic medium; and a pump mechanism which can be connected to the capillaries for filling the capillaries with an electrophoretic medium, the pump mechanism comprising: a plunger; a slider which is bonded to the plunger and moves together with the plunger; a spring which gives force to the slider; a cover which limits the range of displacement of the slider; and a linear motion system which is bonded to the cover and moves linearly; wherein: the cover and the slider move as one body when the electrophoretic medium is taken to the plunger, the plunger is pushed by the action of the spring when the electrophoretic medium is injected from the plunger into the capillaries, the pump mechanism further comprises a slit plate bonded to the slider and an encoder to detect slits in the slit plate; and the encoder is attached to the cover and detects the position of the slider relative to the cover.