GB1324254A - Automatic engraving machine - Google Patents

Abstract

1324254 Engraving machine E P KOTOV V V LEGOSTOV E A STEPANOV A M CHUCHALOV N K MAIOROV G P MEREZHKO A S KOMAROV and N G SOSNITSKY 31 July 1970 37076/70 Heading H4F An engraving arrangement in which an original mounted as a rotating drum is photoelectrically scanned, the material to be engraved being also mounted on a rotary drum, is adapted so that a contour line corresponding to the boundary of the original being scanned is engraved with a predetermined depth. The photo-electric pick-up device is moved parallel to the axis of the rotating drum carrying the original, and is provided with a diaphragm having two apertures also aligned parallel to the drum's axis. The resulting photocurrent from the pick-up device 7, Fig. 2, due to light reflected from the original through these two apertures, is fed via a modulator 14 to a switch 15 which in response to a switching device 16 converts the signal into pulses which are fed via a mixer 17 to the coils of the engraving tool electromagnetic drive 9. When the pick-up device scans across the boundary of the original that is parallel to the drums rotation axis the two apertures are successively aligned with the original and the resulting photocurrent is reduced from a prescribed value to a half and then to zero (or vice versa) depending on the direction of movement of the pick-up device. In addition to being fed to the modulator 14 the photocurrent is also fed to relay 18 adjusted by means of resistor 31 to operate at half of the photocurrent which corresponds to the light flux fed to the photomultiplier at the pick-up from the original via one of the apertures. When the relay 18 operates, multivibrator 19 is triggered, triode 25 of switch 15 is cut off, and a pulse of prescribed magnitude and duration from the multivibrator 19 (corresponding to the boundary of the original) is fed to mixer 17 causing a contour point of predetermined depth to be engraved. When the pick up device scans across the boundary of the original that is perpendicular to the drums rotation axis the period of intersection is relatively long compared with the period of intersection with the parallel boundary and a contour line of predetermined depth is engraved, a continuous signal being applied from the modulator 14 to the mixer 17 (subsequent to a single pulse from the multivibrator 19) since the Zener diode 30 in the relay 18 is caused to conduct which turns on the triode 25 in switch 15 overriding the switching device 16. Modulator 14 is preferably a balanced modulator so that engraving from negative and positive originals may be produced.