Erwin Sick Gmbh Optik-elektronik

Siegfried Mankel

Erwin Sick

Klaus Ostertag

Dieter Ross

Heinz B Schreyer

A light beam 2 from a laser light source 30 is split by a beam splitting arrangement 21, 22 into two slightly convergent light beams which are deflected by a deflecting mirror 31 onto the surface of a mirror wheel 23. The mirror wheel 23 that deflects these light beams via deflecting mirrors 24', 25' onto two strip-like concave mirrors 24, 25 which produce respective parallel scanning light beams which are continuously displaced parallel to themselves in the image spaces of the strip-like concave mirrors. These scanning light beams fall on respective rows of inclined dividing mirrors 9 and 10 which are arranged one behind the other in an alternating sequence. The inclined mirrors deflect the incident light beams through substantially 90.degree. to form a continuous light curtain which can be used to scan web material. Light reflected from the surface of the web or transmitted through holes in the web falls on light gathering devices in the form of either two rows of strip-like Fresnel lenses 5, 6 or two rows of light conducting rods 5', 6'. One light gathering device is associated with each of the inclined mirrors 9, 10. Light gathered by each of the light gathering devices is directed to an associated photoelectric detector 7 which is connected to an electronic processing circuit 8 for evaluating the signals from all the photoelectric detectors.

Monitoring apparatus

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

A banknote condition monitoring apparatus features a mirror wheel (22) located substantially at the focus of a concave mirror strip (25) with an intervening plane mirror (26) to fold the beam path. The mirror wheel (22) scans an incident light beam from a source (28) to form a transmitted light beam in the image space of the concave mirror (25) which is continuously displaced parallel to itself to and fro through the image space. The transmitted light beam is directed via a cylindrical lens (14) onto the surface of a drum (11) carrying the banknotes (12) to be monitored on its peripheral surface by way of air suction via the channels (32). Light remitted from the surface of the banknote is directed through the lower half of the cylindrical lens (14), impinges on a light conducting rod (15) and is detected at an and face of the light conducting rod by a light receiving device (33). The mean output signal from this light receiving device indicates the presence of holed, torn or dog-eared or dirty banknotes but not strips of clear adhesive film which are recognized by the specularly reflected light beam (21) which falls on a stationary photodetector (23). The optical distance of the stationary detector (23) from the drum is equal to that of the mirror wheel scanning device so that the specularly reflected light beam always passes through a stationary point in space.

Banknote condition monitoring apparatus

Hole seeking apparatus for material webs is disclosed which features a light source for projecting a light beam onto a mirror wheel arrangement located optically in front of a concave mirror so as to produce a scanning beam in the image space of the concave mirror. The scanning beam is continuously displaced parallel to itself so as to periodically scan along a scanning path on the material web. The mirror wheel arrangement consists of two substantially identical mirror wheels which lie coaxially on one another and which are displaced by a half pitch. The dimensions of the light bead at its point of incidence on the mirror wheels and the optical geometry of the apparatus are selected to avoid light being scattered at an edge of either of the mirror wheels and passing to either side of the web. Scattered light is thus prevented from falling on a light receiving device arranged behind the web and intended to detect the presence of holes therein. In this way the false recognition of a hole at the margins of the web is prevented.

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Geretsried, Germany

Siegfried Mankel