Patent GB-1048585-A (GB)
Title: Apparatus for the automatic dimensional inspection of an object
Inventor: FOSTER DAVID BLYTHE
IPC: G01N21/90
Filed: 1962-07-20
Abstract: 1,048,585. Electric selective signalling. NORTH ATLANTIC RESEARCH PRODUCTS Ltd. July 19, 1963 [July 20, 1962; Aug. 20, 1962], Nos. 27919/62 and 31819/62. Heading G4H. [Also in Division G1] In apparatus for testing the dimension or shape of an object a pair of photo-cells are placed at predetermined spaced limits representing a dimension of the object the outputs of the photo-cells being combined to indicate that the dimension lies within certain limits. In Fig. 1 (not shown), pairs of photo-cells 3, 4 and 5, 6 are placed at each end of the object 1, each being illuminated by a lamp 7, 8, 9, 10. An object of the correct length covers photo-cells 4 and 5, photo-cells 3 and 6 being uncovered. The outputs of the four photo-cells are gated together, those from photo-cells 4 and 5 being inverted at 21. An output from gate 23 indicates that the object 1 is the correct size. Extra photo-cells may be added so that the objects may be sorted according to dimension. To allow the sensing positions to be placed close together the photo-cells may be connected to bundles of thin optical fibres 24, Fig. 2 (not shown), arranged in a straight line at one end and a bundle at the other for co-operation with the photo-cell. Fine resolutions may be obtained by covering the photo-cell 3, Fig. 3 (not shown), in a housing 26 having a slit 27. In the form of Fig. 4 (not shown) the pair of photo-cells at one end is replaced by a single photo-cell 32 actuated by the shadow of the object 1 falling on it as it moves past the sensing position so as to give a triggering pulse. If, at the instant of the triggering pulse, the pairs of photo-cells 28, 29 and 30, 31 straddle the top and side edges of the object And gate 23 gives an output and the trigger pulse sets flip-flop 33. This checks the two dimensions of the object. A timing device may be inserted in the trigger pulse circuit to reset the flip-flop after a suitable period, e.g. a time slightly greater than the time taken for the object to pass through the apparatus. This prevents the destination of the object being controlled by signals derived from a following object. In another form, Fig. 6 (not shown), a number of photo-cells 37, 41, 42, 43 are provided all of which must be illuminated to obtain the triggering pulse. Operation by a following object is prevented as long as at least one of the guard photo-cells 41, 42, 43 are obscured. The objects may be hot and the photo-cells replaced by infra-red detectors. In the form of Fig. 9 (not shown) an article 51 is compared for shape with an aperture 52. As the object reaches the registered position cell 55 gives a pulse. For a proper match the object obscures all the light from the aperture. Photo-cell 54 accordingly produces a signal, the two signals being used to set flip-flop 33. In the form of Fig. 10 (not shown), a beam of light is reflected several times over the surface of an object. Any projecting burrs or the like, resulting from the manufacture of the object, interrupts the beam and a signal is produced to set flip-flop 33.