1516881 Dimensional gauging SOC SUISSE POUR L'INDUSTRIE HORLOGERE (SSIH) MANAGEMENT SERVICES S A 2 Sept 1975 [9 Sept 1974] 36108/75 Heading G1A A system arranged for the determination of the co-ordinates of certain points on articles comprises an optical projection 1, 2, 7 arranged to form an image 10 of the outline of an article 3 on the lightsensitive face of an opto-electronic scanner 11 in which the scan path is limited to the neighbourhood of the parts of the outline on which these points lie and means for determining the co-ordinates of the points from video signals from the scanner. Via semi-reflecting plate 6 or a beam-splitter cube scanner 11 receives an image of grid 48 alternately with the outline image. The output of amplifier 15 and wave-shaper 16 contains signals which are generated by the scan crossing the outline edge or the grid lines of which gate pulses from clock 17 via circuit 28, which controls the angle of scan, to 'X' and 'Y' counters 26, 27 and digital to analogue converters 24, 25 feeding 'X' and 'Y' summing amplifiers 20, 21, which also receive, via digital to analogue converters 32, 23 from computer controlled storage registers 31, 22, voltages indicating X and Y starting positions. The voltage from 20, 21 controls X and Y scan drivers 18, 19 to drive the scan towards the object's edge, upon reaching which a read-out is commanded from counters 26, 27 and supplied through #X and #Y co-ordinate data registers 29, 30 to the computer. Calibration is by scanning the grid so that counters 26, 27 read out the numbers counted between adjacent grid lines and storing the second differences as calibration corrections. If the process is repeated the correction converges and the correction numbers are stored in the computer for scan linearization in subsequent measurements. Interpolation for positions between the lines is used. The system may be applied to moving or incorrectly orientated objects.
展开▼
