Optical inspection apparatus

Claim 2

An optical inspection apparatus for monitoring a continuously moving rod, said apparatus comprising a circular head through which said rod passes, a first set of fibre optic conductors the ends of which terminate at an inner peripheral surface of said head and which transmits light from a source to said head to illuminate said rod passing therethrough, and a second set of fibre optic conductors the ends of which also terminate at said inner peripheral surface of said head to pick up light reflected from said rod passing through said head and transmit said reflected light to a photosensitive element, said second set of conductors being divided into angularly spaced groups around said head and adjacent groups leading to separate photosensitive elements.

Claim 3

Apparatus according to claim 1, wherein said ends of saiD first set of fibre optic conductors terminate in a first annular array at said inner peripheral surface of said head, and said ends of said second set of fibre optic conductors terminate in a second annular array which is axially displaced from said first array at said inner peripheral surface of said head.

Claim 4

Apparatus according to claim 1, wherein said second set of conductors are divided into at least four angularly spaced groups and said light picked up and transmitted away from said head by diametrically opposed pairs of said groups are combined either before co-operating with a common photosensitive element or by summation of the outputs of two corresponding photosensitive elements.

Claim 5

Apparatus according to claim 3, wherein said photosensitive elements are photoelectric elements from which are produced first electrical signals each corresponding to the light received by one of said diametrically opposite pair of groups of said second set of conductors, there being a comparator circuit in which the level of said first electrical signals is compared to a datum level and a fault signal is produced if said first electrical signals deviate from said datum level by more than a predetermined amount, means for storing said fault signal and means for subsequently providing said stored signal at an output for use in operating a rejection mechanism.

Claim 6

Apparatus according to claim 4, wherein said photoelectric elements are phototransistors or photodiodes.

Claim 7

Apparatus according to claim 4, wherein each photoelectric element is A.C. coupled to the input of an amplifier the output of which is connected to said comparator circuit.

Claim 8

Apparatus according to claim 4, wherein all said photoelectric elements are connected to a common comparator circuit.

Claim 9

Apparatus according to claim 4, which is arranged to be fitted to a continuous rod cigarette making machine and to be used in series with a different rod monitoring apparatus that is also arranged to provide a signal for operating a rejection mechanism for an unacceptable cigarette, wherein said fault signal store of said optical inspection apparatus comprises a first bistable circuit arranged to be triggered by and to hold any fault signal from said comparator circuit upon the sensing of a fault in a portion of said rod corresponding to a cigarette length, a second bistable circuit which is set by any fault signal held by said first bistable circuit and is triggered to receive and hold said fault signal by a first clock pulse corresponding to completion of passage of said rod portion through said optical inspection apparatus, said first clock pulse then resetting said first bistable circuit, and a third bistable circuit adapted to be set by any fault signal held by said second bistable circuit and to be triggered to receive and hold said fault signal by a second clock pulse corresponding to said leading edge of said rod portion beginning it''s passage through said other monitoroing apparatus, said second clock pulse then resetting said second bistable circuit whereby said fault signal is available at the output of said third bistable circuit for use in synchronism with a fault signal from said other monitoring apparatus to operate a rejection mechanism for said cigarette produced by cutting off said rod portion.