Apparatus for controlling operating stroke of reciprocating member, using encoder signal

An apparatus for controlling an operating stroke of a reciprocating member which is adapted to be reciprocated over a predetermined distance by a bidirectional drive motor, through a power transmission mechanism operatively connecting said reciprocating member and said drive motor, comprising:

• stroke setting means for specifying said operating stroke of said reciprocating member;
• an encoder for generating pulses each of which corresponds to a predetermined incremental distance of movement of said reciprocating member;
• counting means for counting said pulses generated by said encoder while said reciprocating member is moved in a forward direction;
• first calculating means for converting the specified operating stroke into the number of said pulses corresponding to a multiple of said incremental distance of movement of said reciprocating member, and for determining a residual distance which is a difference between said specified operating stroke and said multiple;
• second calculating means for converting said residual distance into a corresponding residual time necessary for said reciprocating member to move by said residual distance;
• and
• commanding means for commanding said drive motor to stop an operation thereof causing a further movement of said reciprocating member in said forward direction, at a point of time after a count of said counting means is equal to said number of said pulses calculated by said first calculating means and said residual time has passed.