Patent ID: 7804268

Claim:
An apparatus for controlling injection in an electric injection molding machine including a motor and a screw, the apparatus comprising: an encoder detecting a current position of the screw and outputting the detected position as an encoding signal; a memory storing reference positions of the screw according to a drive of the motor by the passage of time; and a current controller checking an elapse of time that the screw moves from a previous position to a current position through receiving the encoding signal from the encoder, reading out a section of time corresponding to the checked elapse of time from the memory, and controlling a current value applied to the motor based on a difference between a reference position of the screw corresponding to the read-out section of time and a current position of the screw; a subtractor calculating a difference between a reference position of the screw and a current position of the screw; a switching controller generating an instruction current value based on the difference calculated from the subtractor and the difference variation by time, and transmitting the same to the current controller; and a switching section transmitting the encoding signal outputted from the encoder to the current controller and the memory according to a switching operation, wherein the switching section includes: a first switching unit transmitting the encoding signal outputted from the encoder to the memory according to a switching operation of the first switching unit; a second switching unit transmitting the encoding signal outputted from the encoder to the subtractor according to a switching operation of the second switching unit; and a third switching unit transmitting the instruction current value of the switching controller to the current controller according to a switching operation of the third switching unit.