GB1474953A - Recording/playback transducer positioning and adjusting device - Google Patents

Abstract

1474953 Track-changing devices BASF AG 11 July 1974 [12 July 1973] 30717/74 Heading G5R Track changing of a record/playback transducer 4 is effected by a device 1 comprising a transducer support 3 movably mounted in a mounting means 2 and contacting one of a plurality of cam levels 7 of a cam 6, each level 7 corresponding to a respective track 10 on a record medium 9, a motor 8 for stepwise movement of cam 6 to bring a selected cam level 7 into contact with support 3, an indicating element (14), Fig. 4 (not shown), carrying markings (15) each provided in a location corresponding to a respective cam level 7, and monitoring means 16 for sensing the markings (15) and controlling the movements of the motor 8 to control automatically the position of the cam 6 in response to the sensed position of the markings (15) on the indicating element. In a video tape apparatus using magnetic tape 9 having twenty eight longitudinal video tracks 10 of 0À004 inch width and 0À008 inch pitch, optical, fluidic or magnetic means sense the ends of tape 9 and effect reversal of tape drive and operation of a single- or bi-directional stepping motor 8 to step a cam 6 having twenty eight steps 7, with the first and last steps joined by an oblique portion 11. Oblique portion 11 may have mechanical stops to prevent rotation of cam 6 in either direction beyond the last step 7 prior to portion 11. Sup - port 3 carries transducer 4 at one end and a ball 12 at the other, a spring 29 urging ball 12 against cam 6 and urging a pin 21 against a pin 20, these pins ensuring accurate vertical sliding of support 3. The height of transducer 4 relative to a selected track is adjustable over a 0À031 inch range by a conical set screw (23), Fig. 2 (not shown), operable to move ball 12 into and out of a cavity (13) in support 3, and azimuthal adjustment is effected by acting on pin 22 to swing frame 2, support 3 and transducer 4 about pivot pin 25, screws 26 and spring washers 27 maintaining the adjusted azimuth. The circumference or lower surface of cam 6 is provided with the markings (15) in the form of indentations, elevations, openings, electrical or magnetic means for activating the monitoring means 16 which may be an assembly of switches. Another switch responsive to the markings (15) is used to indicate when the first or last cam level is engaged by the support 3.