Pilkington Plc

Pilkington Group Limited

Pilkington Brothers P.l.c.

Barry Raymond Hill

Simon Peter Aldred

David M Ring

A method of inspecting a glazing for faults involves illuminating the glazing with light having a first wavelength to produce a bright-field image, and illuminating the glazing with light having a second wavelength to produce a dark-field image. The bright-field image and dark-field image are captured using a single image capture device. The bright-field and dark-field images may be focussed onto the image capture device by a common lens. In addition, a shadowgraph image may be recorded simultaneously. The inspection method provides an improved fault detection system for glazings, such as automotive glazings.

Glazing inspection

A method of forming a shadowgraph image is described, comprising the steps of illuminating a glazing (), e.g., a vehicle windscreen, with light from a localized light source (), said light being expanded and collimated by a lens optical system () or a mirror optical system, forming a virtual shadowgraph image of the glazing in a virtual image plane (), which may be positioned behind or in front of the glazing: and imaging the virtual image onto a CCD camera (). The glazing may be moving relative to the light source or may be stationary. Furthermore, a method of glazing inspection is described, comprising forming a shadowgraph image as outlined above; processing the shadowgraph image to exclude measurement points corresponding to obscure areas of the glazing as non-valid measurement points: obtaining a processed image by determining an illumination value for each valid measurement point; constructing a reference image by scanning a convolution window point by point over the processed image; and comparing the illumination value of the corresponding point of the reference image.

A method of determining the optical quality of a glazing which includes at least one area having a reduced light transmission, involves producing a shadowgraph image of the glazing and measuring the illumination of the glazing at a plurality of measurement points arranged in an array extending over the glazing. The deviation in illumination from a desired value at each measurement point is determined and the at least one area of reduced light transmission is omitted from the array of measurement points.

Method to determine the optical quality of a glazing

An interferometer is provided for producing an interference pattern from light such as laser light which travels along first and second optical paths and at the end of each such path there is a respective fixed mirror for directing light to a common optical path. Means are provided to vary the optical path length of light in the or each first or second optical path to produce an interference pattern in the common optical path, which means comprises a pair of parallel-plane optical flats in accordance with one embodiment of the invention, which are each rotated in an oscillating manner to produce a linearly varying optical path length during rotation. According to another aspect of the invention first detector means are provided for detecting a reference part of the interference pattern produced to derive therefrom a reference signal, and second detector means are provided for receiving the interference pattern to thereby derive signals indicative of successive parts of the interference pattern. Means are provided for comparing the reference and successive interference pattern signals to derive therefrom signals which indicate the optical path difference corresponding to the interference pattern.

Dual path interferometer with varying difference in path length

An apparatus and a method for inspecting cullet for the presence of unwanted materials among the pieces of glass. A light source such as a laser directs light onto the cullet. At least one array of at least two light detectors is positioned to detect reflected light from the cullet. The detectors differentiate between non-uniformly scattered light from the cullet and generally uniformly scattered light from the debris. Signalling means are provided to signal the differentiation thereby to indicate the presence of debris in the cullet under inspection. When cullet is present on a moving cullet belt, light from the light source is intermittently scanned over the cullet in a raster-type scan. A multi-faceted rotatable mirror may be employed intermittently to reflect light onto the cullet.

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St. Helens, United Kingdom

Barry Raymond Hill