Erwin Sick Gmbh Optik-elektronik

Erwin Sick Gmbh

Klaus Ostertag

Dieter Ross

Erwin Sick

Klaus Weber

Karl Pietzsch

Siegfried Mankel

Heinz B Schreyer

An optical surface inspection apparatus for material webs comprises an illuminating means (11) for generating a strip of light (12) on the surface (19) to be inspected and a light receiving means (13) which receives the light emitted (diffusely reflected) from the surface region illuminating by the strip of light (12) and directs it to a photoreceiving arrangement, which delivers a signal representative of web faults to an electronic processing circuit (16). The light receiving means (13) has at least one row camera (14) which receives light remitted from a line illuminated by the strip of light (12) and forms an image of the line on the diode row (15). The light receiving means is also arranged at such a shallow observing angle .alpha. relative to the tangential plane to the surface at the location of the strip of light (12) that faults (20) which project slightly out of the surface appear to the row camera (14) in shadow outline against the light background of the strip of light (12).

Optical surface inspection apparatus

In a scanner for the optical checking of objects such as CD-discs there is provided a coherent light source; a light deflecting device which allows a light beam emitted from the light source to sweep over the object in a substantially linear scanning movement, with the optical axis of the light beam subtending a small angle with a normal to the object surface transverse to the scanning direction; and a detector for detecting light which is reflected back from the object. In the present arrangement the optical axis of the light beam also subtends a small angle with the normal to the object surface in the scanning direction. This makes it possible to avoid disturbing modulation of the detector signal due to interference effects.

Scanner for the optical scanning of objects

Faults in a material web are detected by scanning the web with a beam of light along a line transverse to its direction of movement and by detecting the angular ranges into which the incident light is scattered by these faults. For this purpose a light conducting rod is arranged parallel to the scanned line in a reception plane. The light conducting rod has a stepped prism arrangement along its side surface opposite to the light inlet and the inclination of the individual, unmirrored, prism surfaces is such that specularly reflected light passes through the prisms whereas scattered light falls on the prism surfaces at angles of total reflection and is reflected to a photodetector at an end face of the light conducting rod.

Fault detection apparatus for material webs

Fault detection apparatus for material webs comprising a light transmitting device for generating a line of light on the material web and an elongate light receiving device which extends parallel to the line of light and is so arranged that it can receive light which enters a predetermined reception plane from the line of light, with the predetermined reception plane lying at a specified angle to the plane normal to the material web and containing the line of light, and with the line of light being formed by a bead of light which scans the web point by point, line by line. The light receiving device (43) comprises a plurality of light receivers (1 to 30) which can be selectively switched in, with at least one of the light receivers being switched out at each particular instant.

Faults in a material web 47 are detected by scanning the web with a beam of light 37 along a line transversely to its direction of movement F and by detecting the angular ranges into which the incident light is scattered by these faults. For this purpose an elongate light receiving device 33, which is preferably a light conducting rod, extends parallel to the line of scanning on the web with the axis of the light conducting rod and the line of scanning defining a reception plane. An elongate angular range filter 34 is arranged in this plane between the line of scanning and the light conducting rod and serves to deflect beams of light 35 close to the angle of specular reflection away from the light conducting rod. Light which is scattered in other angular ranges within the reception plane is however transmitted by the angular range filter 34 to the light conducting rod and is detected by a photoelectric detector positioned at the end face thereof. The system can also operate in transmission in which case the normally transmitted ray is deflected away from the light conducting rod. In this way the scattered beams which contain the useful information are detected without being swamped by the remainder of the light. A number of different angular range filters are disclosed including holograms 34, grids of thin plates 41, an array of stepped prisms 39 and an array of photoelectric detectors 43. Possible scanning devices include a fluorescent tube and beam scanning apparatus using a scanning beam 37 which is either continuously displaced parallel to itself (FIG. 1) or swept angularly through a sector-like range (FIG. 2).

Optical fault seeking apparatus for material webs uses an optical scanning device to scan the material webs point by point line by line. The optical scanning device consists of a laser light source (17) which projects a light beam via a micro-objective (19), a cylindrical lens (20), and a further objective onto a mirror wheel arrangement (14) which is located substantially at the focus of a strip-like concave mirror (23). A light beam (24) is produced in the image space of the strip-like concave mirror (23) and generates a scanning light bead in a scanning plane through which the material web passes. The mirror wheel arrangement (14) has at least first and second alternately operating types of mirror surfaces which serve to alternately project light beads of different size and/or shape onto the material web thus enabling different types of fault to be reliably detected. The different types of scanning light bead are produced either by different curvatures of the faces (15) and (17) of the mirror wheel arrangement (14) or by the use of other optical means alone or in combination with differently shaped faces of the mirror wheel. Certain embodiments operate using two mirror wheels in tandem.

Optical fault seeking apparatus

Apparatus for monitoring for faults in translucent strip material, such as photographic film, comprises a transport device 16, 12, 13, 22 for continuously moving the film 11 in its longitudinal direction and an optical scanning device 23 including a beam divider 21 which divides a single series of scanned light beams 14 into first and second sets of scanned light beams 14a 14b. The first set of light beams 14a is used to carry out transmission measurements on the film as it passes in tensioned condition between two spaced apart rollers 12, 13 and the second set 14b is used to carry out measurements in reflection as the film passes around the surface of a roller 16. The roller 16 has an air permeable surface and air is blown through this surface from the inside of the roller to form an air cushion between the film and the roller. Faults are detected by the electronic processing circuitry 18 in response to variations in the transmission and reflection measurements carried out by the light detectors 15 and 17.

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Munich, Germany

Klaus Ostertag