120 and a highlight video level 122 when the white video level 118 is present in the composite drive signal 116 the actuator 52 contracts to the length lou u2122 and the diamond stylus 95 is raised out of contact with the cylinder surface 28 as shown by the stylus position 124 when the dc video component 106 goes from the white video level 118 to the black video level 120 the actuator 52 elongates to a length l in and the diamond stylus 95 moves into engraving contact with the cylinder surface 28 as shown by the stylus position 126 when the dc video component shifts to the highlight video level 122 the actuator elongates to a length somewhere between l in and l out and the diamond stylus 95 oscillates in and out of engraving contact with the cylinder 24 as shown by the stylus position 128 this oscillation in turn causes the engraver 10 to engrave the predetermined pattern while the forms of the device herein described constitute the preferred embodiments of the invention it is to be understood that the invention is not limited to these precise forms of device and that changes may be make therein without departing from the scope of the invention which is defined in the appended claims for instance instead of introducing the bias current through the separate bias coil 56 the bias current may be introduced by means of a magnet or by applying dc bias current to the drive coil 54 through a series inductor placed in parallel with.