Side support device in seat back of an automotive seat

A side support device in a seat back of an automotive seat, comprising:

• a seat back frame having a pair of lateral frame sections;
• a pair of side support frames, each being rotatably mounted on one of said pair of lateral frame sections of said seat back frame;
• a drive mechanism disposed at one of said pair of lateral frame sections of said seat back frame, said drive mechanism including:
• a motor;
• a lead screw connected operatively with an output shaft of said motor, said lead screw being so disposed as to extend generally vertically relative to said one of said pair of lateral frame sections;
• a nut member in a threaded engagement with said lead screw, said nut member having a pin provided therewith;
• an arm means having two ends, wherein one end is engaged with said pin of said nut member;
• a first bracket fixed on said one of said pair of lateral frame sections,
• a shaft which is rotatably supported on said first bracket, wherein another end of said arm means is fixed to said shaft;
• a link means having a base end fixed to a free end of said shaft;
• a second bracket fixed on said one of said pair of lateral frame sections;
• an actuator plate which is rotatably supported on said second bracket, said actuator plate having one end portion coupled operatively to a free end of said link means, and having another opposite end portion to which one end of one of said pair of side support frames is fixed;
• a connecting rod extended between said pair of side support frames, said connecting rod having one end pivotally connected to another end portion of said actuator plate and having another end operatively connected to another of said pair of side support frames;
• and
• wherein operation of said motor causes both said pair of side support frames to be moved inwardly toward or outward away from each other.