Stylus actuator

Claim 1

In a graphic recorder having a recording element for recording information on a recording medium, a first pair of guide rods disposed adjacent a plotting surface along a first recording axis, a pair of carriage members adapted for movement along said first pair of guide rods, a second pair of guide rods mounted between said carriage members and positioned along a second recording axis orthogonal with said first recording axis, and a stylus holder slidably mounted on said second guide rods for movement over a plotting surface, said stylus holder including a pivotal plate carrying said recording element actuator comprising: selectively actuable energizing means having first and second rotational positions; a rotatable shaft connected to said energizing means and disposed in axial parallelism with said first pair of guide rods; first cam means slidably mounted on said rotatable shaft and carried by one of said carriage members, said first cam means having a substantially cylindrical shape with a groove extending longitudinally along the outer surface thereof; pivotal bar means disposed parallel to said second pair of guide rods and passing between said pivotal plate and said plotting surface, said pivotal bar means having a first rotational position about a longitudinal axis thereof for holding said recording element in a non-recording position and a second rotational position for holding said recording element in a recording position; and coupling means operatively connected to said one of said carriage members to transmit rotational motion of said energizing means to said pivotal bar means for selectively moving said recording element in and out of engagement with said recording medium, said coupling means including pushrod means engaging said first cam means at one end thereof and said pivotal bar means at the other end thereof, wherein said rod means rests in said groove in said first cam means in one rotatable position and on the outside wall of said first cam means in the second rotatable position so that any force exerted by said rod means upon said first cam means is directed toward the axis of said first cam means to thereby preclude torque from being applied to said first cam means and said energizing means in either of two rotatable positions thereof.