Sorting machine

Claim 3

A method as claimed in claim 1 characterised in that :the passage of the objects (13) past the background (22) is periodically stopped temporarily, and each said examination occurs at least in part during the stoppage of the objects.

Claim 4

A method as claimed in claim 2 characterised in that each said examination comprises comparing the average reflectance, transmission or emission of light by the background (22) and objects (13) collectively shortly prior to the respective stoppage with the reflectance, transmission or emission of light by the background alone during the respective stoppage.

Claim 8

A sorting machine comprising viewing means (20) for viewing objects to be sorted in a sorting zone (14) to determine whether any of them, at least in part, reflects, transmits or emits light in a predetermined part or parts of the spectrum to an undesired extent or in an undesired ratio; a background (22) which is in the field of view of the viewing means (20); feeding means (16,17) for passing the objects (13) through the sorting zone (14) and past the background (22) so that the objects (13) may be viewed against the background (22); and separating means (24) for effecting relative separation between any undesired objects which have been so viewed and the remaining objects, characterised by examination means for periodically effecting an examination as to whether a predetermined relationship exists between the reflectance, transmission or emission of light in a predetermined part or parts of the spectrum by the background (22) and the reflectance, transmission or emission of light in the said part or parts of the spectrum by the average of the objects (13); and adjustment means (32), controlled by the examination means (26,40,41) for effecting where necessary an adjustment of the reflectance, transmission or emission of light by the background (22) and/or an adjustment of the incident radiation onto the objects (13) so as to tend to maintain the said predetermined relationship substantially constant.

Claim 9

A sorting machine comprising viewing means (20) for viewing objects to be sorted in a sorting zone (14) to determine whether any of them, at least in part, reflects, transmits or emits light in a predetermined part or parts of the spectrum to an undesired extent or in an undesired ratio; a background (22) which is in the field of view of the viewing means (20); feeding means (16,17) for passing the objects (13) through the sorting zone (14) and past the background (22) so that the objects (13) may be viewed against the background (22); and separating means (24) for effecting relative separation between any undesired objects which have been so viewed and the remaining objects, characterised by examination means for periodically effecting an examination as to whether a predetermined relationship exists between the reflectance, transmission or emission of light in a predetermined part or parts of the spectrum by the background (22) and the reflectance, transmission or emission of light in the said part or parts of the spectrum by the average of the objects (13); and adjustment means (32), controlled by the examination means (26,40,41) for effecting where necessary an adjustment of the reflectance, transmission or emission of light by the background (22) and/or an adjustment of the incident radiation onto the objects (13) so as to tend to maintain the said predetermined relationship substantially constant.

Claim 10

A sorting machine as claimed in claim 7 characterised by means (45) for periodically stopping the feeding means (16,17) so as to stop the passage of the objects (13) past the background (22), the examination means (26,40,41) being arranged to effect each said examination at least in part during a said stoppage of the objects.

Claim 11

A sorting machine as claimed in claim 8 characterised in that the examination means (26,40,41) comprises means (41) for comparing the average reflectance, transmission or emission of light by the background (22) and objects (13) collectively shortly prior to the said stoppage, with reflectance, transmission or emission of light by the background (22) alone during the stoppage.

Claim 12

A sorting machine as claimed in claim 9 characterised in that the viewing means are photo-electric viewing means (20), the examination means comprising an averaging circuit (41) for producing a voltage signal representative of the average electrical output of the viewing means (20), the examination means also comprising electrical means (26) arranged to receive said voltage signal and also to receive a further voltage signal which is representative of the instantaneous electrical output of the viewing means (20), said electrical means (26) being arranged to produce a difference signal which is the difference between the two voltage signals and which controls the adjustment means (32).

Claim 13

ll. A sorting machine as claimed in claim 10 characterised in that the electrical means comprise a processor (26) which controls the feeding means (17), the processor being programmed to stop the feeding means at intervals whose length is inversely related to the magnitude of the difference signal.

Claim 14

A sorting machine as claimed in claim 10 or 11 characterised in that the electrical means (26) controls the adjustment means (32) so that, if a difference signal is produced at an examination, the resulting said adjustment is initially insufficient to fully restore the said predetermined relationship and a further difference signal is therefore produced at the next examination, the electrical means (26) being arranged to determine from the magnitude of these two successive difference signals the necessary signal to be sent to the adjustment means (32) to complete the said adjustment.

Claim 15

A sorting machine as claimed in any one of claims 8-12 characterised in that there are means (57), operative during each said stoppage, for measuring the output of the viewing means (20) and applying, if necessary, a correction factor in said electrical means (26) to maintain the sensitivity of said viewing means (20) substantially constant.

Claim 16

A sorting machine as claimed in any one of claims B-13 characterised in that there are means (61), operative during the passage of the objects past the background, for indicating the rate of separation of undesired objects.

Claim 17

A sorting machine as claimed in any one of claims 7-14 characterised in that the adjustment means comprises a motor (31) for altering the angular disposition of the background (22).

Claim 18

A sorting machine as claimed in any one of claims 7-15 characterised in that there is at least one light source (33) whose light is directed onto the background (22) or onto the objects (13), the adjustment means (32) comprising means (34) for varying the light output of the said light source or sources (33).

Claim 19

A sorting machine as claimed in any one of claims 7-16 characterised in that the background is provided with light-emitting diodes or with liquid crystal material, the adjustment means (32) being arranged to vary the total light output of the diodes or liquid crystal material.

Claim 20

A sorting machine as claimed in any preceding claim characterised in that the sorting machine has at least one plurality (10) of separate but adjacent supports (11) for conveying the objects (13) to the sorting zone (14); a plurality of detectors (20) for each support (11); and means (21) ensuring that each detector (20) is in operation responsive to objects (13) which are in, or have been delivered to the sorting zone from, a respective portion (lla) only of the respective support.

Claim 21

A sorting machine for effecting relative separation between objects (13) which have and those which do not have a predetermined characteristic, said sorting machine having a sorting zone (14) provided with a plurality of detectors (20) each of which is responsive to said characteristic, and separating means (24), controlled by the detectors (20), for effecting the said relative separation characterised in that there are at least one plurality (10) of separate but adjacent supports (11) for conveying the objects (13) to the sorting zone (14); a plurality of said detectors (20) for each support (11): and means (21) ensuring that each detector is in operation responsive to objects (13) which are in, or have been delivered to the sorting zone (14) from, a respective portion (lla) only of the respective support.

Claim 22

A sorting machine for effecting relative separation between objects (13) which have and those which do not have a predetermined characteristic, said sorting machine having a sorting zone (14) provided with a plurality of detectors (20) each of which is responsive to said characteristic, and separating means (24), controlled by the detectors (20), for effecting the said relative separation characterised in that there are at least one plurality (10) of separate but adjacent supports (11) for conveying the objects (13) to the sorting zone (14); a plurality of said detectors (20) for each support (11): and means (21) ensuring that each detector is in operation responsive to objects (13) which are in, or have been delivered to the sorting zone (14) from, a respective portion (lla) only of the respective support.