Monitoring systems

Claim 2

Apparatus for monitoring the presence of an irregularity in the surface of a web of material during movement of the web over a curved guide surface having an axis of curvature which is aligned transversely to the direction of movement of the web and which guide surface is subject to sagging deflection, the monitoring apparatus comprising means for directing a sharply defined light beam skewed at a slight angle relative to said axis of curvature over the surface of the web of material so as to ensure that the light beam is aligned closely parallel to the surface of the web to thereby compensate for the sagging deflection, and photoelectric light receiving means arranged in the vicinity of the light ray for generating an output signal which changes as a function of the change in the light received by the light receiving means in response to the entry of the irregularity into the light beam.

Claim 3

Apparatus according to claim 1 wherein the light beam comprises a laser beam.

Claim 4

Apparatus according to claim 1 wherein the light beam is received by the said light detecting means after it crosses the web, the last mentioned means comprising a differential photo-receiver and a differential amplifier operatively coupled therewith.

Claim 5

Apparatus according to claim 1 wherein the light detecting means is arranged alongside the light beam and receives light reflected from the surface irregularity.

Claim 6

Apparatus according to claim 1 wherein the guide surface comprises a cylindrical surface of a roller.

Claim 7

Apparatus according to claim 1 wherein the means for directing comprises a laser, and including first and second successive optical wedges positioned to intercept the light beam generated by the laser, the wedges being further oriented so that the light beam impinges thereon at an angle, the wedges being rotatable about the axis of the light beam for aligning the light beam substantially parallel to the surface of the web.

Claim 8

Apparatus for monitoring a web of material to determine the presence of irregularities in the surface of the web, web moving over a curved guide surface having an axis of curvature which is oriented transversely to the direction of movement of the web and which guide surface is subjected to sagging deflection in a direction perpendicular to the axis, the monitoring apparatus comprising: means for directing a sharply defined light beam over the surface of the web material in close proximity therewith, the light beam defining a slight angle relative to the axis of curvature to ensure that the light beam is aligned closely parallel to the surface of the web by compensating for the sagging deflection of the guide surface, photoelectric light receiving means for generating an output signal which is responsive to the magnitude of light received thereby, and means positioning the light receiving means so that it receives light from the beam and generates an output signal which is a function of the received light, whereby the entry of the web surface irregularity into the light beam changes the light received by the light receiving means and thereby causes a corresponding change in the output signal.

Claim 9

Apparatus for monitoring a web of material to determine the presence of irregularities in the surface of the web, web moving over a curved guide surface having an axis of curvature which is oriented transversely to the direction of movement of the web and which guide surface is subjected to sagging deflection in a direction perpendicular to the axis, the monitoring apparatus comprising: means for directing a sharply defined light beam over the surface of the web material in close proximity therewith, the light beam defining a slight angle relative to the axis of curvature to ensure that the light beam is aligned closely parallel to the surface of the web by compensating for the sagging deflection of the guide surface, photoelectric light receiving means for generating an output signal which is responsive to the magnitude of light received thereby, and means positioning the light receiving means so that it receives light from the beam and generates an output signal which is a function of the received light, whereby the entry of the web surface irregularity into the light beam changes the light received by the light receiving means and thereby causes a corresponding change in the output signal.

Claim 10

Apparatus according to claim 7 wherein the positioning means locate the light receiving means so that the latter receives the light directly from the means for directing a sharply defined light beam.

Claim 11

Apparatus according to claim 7 wherein the positioning means locate the light receiving means so that the latter receives light reflected from the surface of the web.