Method and apparatus for measuring mutually perpendicular dimensions

Claim 3

A method as claimed in claim 1 wherein the light beam scanned across the zone in the direction parallel to said first dimension falls upon a first photo-electric transducer except when the beam impinges upon the workpiece and the beam scanned across the zone in the direction parallel to said second dimension falls upon a second photo-electric transducer except when the beam impinges upon the workpiece.

Claim 4

A method as claimed in claim 2 wherein each photo-electric transducer produces an electrical signal when light falls thereon and cessation of the signal when the light beam initially impinges on the workpiece initiates the counting of a train of fixed frequency clock pulses and the re-appearance of the signal when the light beam moves off of the workpiece stops the counting of the pulses.

Claim 5

A method as claimed in claim 1 modified in that said light beam is split into two beams and said two beams simultaneously scan the workpiece in the directions parallel to said first and second dimension respectively.

Claim 6

A method as claimed in claim 4 wherein successive scans parallel to the same dimension are in opposite directions.

Claim 7

A method as claimed in claim 5 wherein the light beam scanned across the zone in the direction parallel to said first dimension falls upon a first photoelectric transducer except when the beam impinges upon the workpiece and the beam scanned across the zone in the direction parallel to said second dimension falls upon a second photo-electric transducer except when the beam impinges upon the workpiece.

Claim 8

A method as claimed in claim 6 wherein each photo-electric transducer produces an electrical signal when light falls thereon and cessation of the signal when the light beam initially impinges on the workpiece initiates the counting of a train of fixed frequency clock pulses and the re-appearance of the signal when the light beam moves off of the workpiece stops the counting of the pulses.

Claim 9

Apparatus suitable for determining first and second mutually perpendicular cross-sectional dimensions of an elongate workpiece comprising a measuring zone for receiving the workpiece, a single light source capable of producing a narrow beam of light, optical means for repeatedly scanning a beam of light from said source at a known speed across said zone in a first direction at right angles to the direction of the beam, successive scans being interdigitated with scans by the beam across the zone at a known speed in a second direction which is at right angles to the direction of the beam and at right angles to the first direction, optical means for receiving light passing through said zone in the first direction and focussing said light on to a first photo-electric transducer capable of producing an electrical signal when light falls thereon, optical means for receiving light passing through said zone in said second direction and focussing said light on to a second photoelectric transducer capable of producing an electrical signal when light falls thereon and each transducer having electronic means associated therewith for effecting measurements of the time during each scan in which light is obscured from the transducer when a workpiece is present in the zone, each of said measurements being representative of a dimension of the workpiece being scanned, and means for averaging the measurements from a plurality of scans in said first direction to determine the first dimension of the workpiece, and from a plurality of scans in said second direction to determine said second dimension of said workpiece.

Claim 10

Apparatus suitable for determining first and second mutually perpendicular cross-sectional dimensions of an elongate workpiece comprising a measuring zone for receiving the workpiece, a single light source capable of producing a narrow beam of light, optical means for repeatedly scanning a beam of light from said source at a known speed across said zone in a first direction at right angles to the direction of the beam, successive scans being interdigitated with scans by the beam across the zone at a known speed in a second direction which is at right angles to the direction of the beam and at right angles to the first direction, optical means for receiving light passing through said zone in the first direction and focussing said light on to a first photo-electric transducer capable of producing an electrical signal when light falls thereon, optical means for receiving light passing through said zone in said second direction and focussing said light on to a second photoelectric transducer capable of producing an electrical signal when light falls thereon and each transducer having electronic means associated therewith for effecting measurements of the time during each scan in which light is obscured from the transducer when a workpiece is present in the zone, each of said measurements being representative of a dimension of the workpiece being scanned, and means for averaging the measurements from a plurality of scans in said first direction to determine the first dimension of the workpiece, and from a plurality of scans in said second direction to determine said second dimension of said workpiece.

Claim 11

Method as claimed in claim 2 in which the light beam falling upon each transducer is focussed on said transducer.

Claim 12

Apparatus as claimed in claim 8 wherein the optical scanning means includes means for splitting the light beam whereby said scans in the two mutually normal directions are made simultAneously.

Claim 13

Apparatus as claimed in claim 10 wherein said splitting means comprises a beam splitter block having an equal transmission/reflection screen whereby the light beam impinging thereon is split into two beams mutually at right angles.

Claim 14

Apparatus as claimed in claim 10 wherein said beam splitter block is associated with a prism which causes the light beam to be directed on to the screen first in one direction and then in a direction at right angles thereto whereby the two beams leaving the splitter block are scanned across the zone simultaneously in mutually perpendicular directions with successive scans in each of said directions being in opposite directions.

Claim 15

Apparatus as claimed in claim 8 wherein the optical means for scanning the light beam includes an n sided reflecting polygon rotatable at a known constant speed.

Claim 16

Apparatus as claimed in claim 8 wherein the single light source is a laser.

Claim 17

Apparatus suitable for determining first and second mutually perpendicular cross sectional dimensions of an elongate workpiece comprising a measuring zone for receiving the workpiece, a laser, a mirror for reflecting a narrow light beam from the laser onto the reflecting surfaces of a rotatable n sided polygon, means for rotating said polygon at a known constant speed, a prism arranged to receive the reflected light from the polygon and to reflect the beam in one direction during the first part of the scan and in another direction during the second part of the scan, optical means for directing the beam during the first part of the scan across the measuring zone, optical means for focussing the beam passed across the zone onto a first photo-electric transducer, electronic means associated with the transducer for determining the time during each scan in which the beam impinges upon a workpiece in the zone and electronic means for determining the dimension of the workpiece from a plurality of scans, optical means for directing the beam during the second part of each scan across the measuring zone in a direction at right angles to the beam during the first part of each scan, optical means for focussing the beam passed across the zone during the second part of each scan onto a second photo-electric transducer, electronic means associated with the second transducer for determining the time during each scan in which the beam impinges upon a workpiece in the zone and electronic means for determining the dimension of the workpiece from a plurality of scans.

Claim 18

Apparatus suitable for determining first and second mutually perpendicular cross sectional dimensions of an elongate workpiece comprising a measuring zone for receiving the workpiece, a laser, a mirror for reflecting a narrow light beam from the laser onto the reflecting surfaces of a rotatable n sided polygon, means for rotating said polygon at a known constant speed, a prism arranged to receive the reflected light from the polygon and to reflect the beam in one direction during the first part of the scan and in another direction during the second part of the scan, optical means for directing the beam during the first part of the scan across the measuring zone, optical means for focussing the beam passed across the zone onto a first photo-electric transducer, electronic means associated with the transducer for determining the time during each scan in which the beam impinges upon a workpiece in the zone and electronic means for determining the dimension of the workpiece from a plurality of scans, optical means for directing the beam during the second part of each scan across the measuring zone in a direction at right angles to the beam during the first part of each scan, optical means for focussing the beam passed across the zone during the second part of each scan onto a second photo-electric transducer, electronic means associated with the second transducer for determining the time during each scan in which the beam impinges upon a workpiece in the zone and electronic means for determining the dimension of the workpiece from a plurality of scans.