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Title: Inspection of containers
Claims: I claim: 1. Apparatus for detecting the presence of extraneous matter and/or cracks in translucent containers, said apparatus comprising: an inspection zone; means for rotating a translucent container within the inspection zone; means for generating and vertically scanning a spot beam of light in the inspection zone; a light collection apparatus in the inspection zone; means for generating an electrical inspection signal corresponding to the amount of light passing through the translucent container and impinging on the light collection apparatus; means for synchronously generating a predetermined electrical acceptance signal the value of said acceptance signal being a function of the vertical position of the spot beam of light relative to the container, and means for comparing said inspection signal with said predetermined electrical acceptance signal; and means for generating a rejection signal when the intensity of light passing through the translucent container is below a predetermined value measured by the said acceptance signal. 2. Apparatus as recited in claim 1, in which the means for generating the acceptance signal includes a plurality of photosensors for sensing the vertical position of the spot beam of light, and a variable electrical signal output network connected to be controlled by said plurality of photosensors. 3. Apparatus as recited in claim 2, in which means is provided for scanning the spot beam of light vertically and horizontally in the inspection zone which means comprises; means for generating a vertically scanning slit of light, and projecting the latter towards the inspection zone; and a masking member containing a vertical slit being movable horizontally in the path of the scanning slit of light so as to occlude a portion of the latter and thereby resolve the vertical scanning slit of light into a spot beam scanning vertically and horizontally in the inspection zone. 4. Apparatus as recited in claim 3, in which there is provided; a drum adapted for rotation; a plurality of plane mirrors tangentially mounted on the drum; a light source adapted to project a slit of light on to the drum whereby each rotating mirror resolves the straight slit of light into a scanning slit of light; a cylindrical column below the drum having a vertical slot the axis of which column is perpendicular to the axis of the drum; a plurality of plane mirrors adjustably mounted within the column at an angle to the axis of the column whereby in use the scanning slit of light is reflected from each in turn of the plane mirrors so as to pass through the vertical slot in the column towards the inspection zone, the inclination of the reflective surface of each mirror to the vertical axis of the column is adjustable so that the angle of incidence of the spot beam of light on the container is the optimum angle for the detection of extraneous matter and cracks. 5. Apparatus as recited in claim 2, in which ambient light correction means is provided for determining prior to inspection the electrical signal corresponding to the effect of ambient light impinging on the light collection apparatus, and in which said ambient light signal is electrically subtracted from the inspection signal during inspection of the translucent container. 6. Apparatus as recited in claim 5, in which means is provided for scanning the spot beam of light vertically and horizontally in the inspection zone which comprises; means for generating a vertically scanning slit of light, and projecting the latter towards the inspection zone; and a masking member containing a vertical slit being movable horizontally in the path of the scanning slit of light so as to occlude a portion of the latter and thereby resolve the vertical scanning slit of light into a spot beam scanning vertically and horizontally in the inspection zone. 7. An apparatus as recited in claim 6, in which there is provided; a drum adapted for rotation; a plurality of plane mirrors tangentially mounted on the drum; a light source adapted to project a slit of light on to the drum whereby each rotating mirror resolves the straight slit of light into a scanning slit of light; a cylindrical column below the drum having a vertical slot the axis of which column is perpendicular to the axis of the drum; a plurality of plane mirrors adjustably mounted within the column at an angle to the axis of the column whereby in use the scanning slit of light is reflected from each in turn of the plane mirrors so as to pass through the vertical slot in the column towards the inspection zone, the inclination of the reflective surface of each mirror to the vertical axis of the column is adjustable so that the angle of incidence of the spot beam of light on the container is the optimum angle for the detection of extraneous matter and cracks. 8. Apparatus as recited in claim 5, in which the ambient light correction means comprises: a differential amplifier; means for feeding the inspection signal to the differential amplifier; a sample and hold circuit operatively connected to the light collection apparatus for holding an electrical signal corresponding to the ambient light impinging on the light collection apparatus prior to inspection; and means for feeding the said ambient light signal to the differential amplifier whereby the signal output of the amplifier is the electrical difference between the inspection signal and the ambient light signal. 9. Apparatus as recited in claim 8, in which means is provided for scanning the spot beam of light vertically and horizontally in the inspection zone which means comprises; means for generating a vertically scanning slit of light, and projecting the latter towards the inspection zone; and a masking member containing a vertical slit being movable horizontally in the path of the scanning slit of light so as to occlude a portion of the latter and thereby resolve the vertical scanning slit of light into a spot beam scanning vertically and horizontally in the inspection zone. 10. Apparatus as recited in claim 9, in which there is provided; a drum adapted for rotation; a plurality of plane mirrors tangentially mounted on the drum; a light source adapted to project a slit of light on to the drum whereby each rotating mirror resolves the straight slit of light into a scanning slit of light; a cylindrical column below the drum having a vertical slot the axis of which column is perpendicular to the axis of the drum; a plurality of plane mirrors adjustably mounted within the column at an angle to the axis of the column whereby in use the scanning slit of light is reflected from each in turn of the plane mirrors so as to pass through the vertical slot in the column towards the inspection zone, the inclination of the reflective surface of each mirror to the vertical axis of the column is adjustable so that the angle of incidence of the spot beam of light on the container is the optimum angle for the detection of extraneous matter and cracks. 11. Apparatus as recited in claim 1, in which ambient light correction means is provided for determining prior to inspection the electrical signal corresponding to the effect of ambient light impinging on the light collection apparatus, and in which said ambient light signal is electrically subtracted from the inspection signal during inspection of the translucent container. 12. Apparatus as recited in claim 11, in which the ambient light correction means comprises: a differential amplifier; means for feeding the inspection signal to the differential amplifier; a sample and hold circuit operatively connected to the light collection apparatus for holding an electrical signal corresponding to the ambient light impinging on the light collection apparatus prior to inspection; and means for feeding the said ambient light signal to the differential amplifier whereby the signal output of the amplifier is the electrical difference between the inspection signal and the ambient light signal. 13. Apparatus as recited in claim 12, in which means is provided for scanning the spot beam of light vertically and horizontally in the inspection zone which means comprises; means for generating a vertically scanning slit of light, and projecting the latter towards the inspection zone; and a masking member containing a vertical slit being movable horizontally in the path of the scanning slit of light so as to occlude a portion of the latter and thereby resolve the vertical scanning slit of light into a spot beam scanning vertically and horizontally in the inspection zone. 14. Apparatus as recited in claim 13, in which there is provided; a drum adapted for rotation; a plurality of plane mirrors tangentially mounted on the drum; a light source adapted to project a slit of light on to the drum whereby each rotating mirror resolves the straight slit of light into a scanning slit of light; a cylindrical column below the drum having a vertical slot the axis of which column is perpendicular to the axis of the drum; a plurality of plane mirrors adjustably mounted within the column at an angle to the axis of the column whereby in use the scanning slit of light is reflected from each in turn of the plane mirrors so as to pass through the vertical slot in the column towards the inspection zone, the inclination of the reflective surface of each mirror to the vertical axis of the column is adjustable so that the angle of incidence of the spot beam of light on the container is the optimum angle for the detection of extraneous matter and cracks. 15. Apparatus as recited in claim 11, in which means is provided for scanning the spot beam of light vertically and horizontally in the inspection zone which means comprises; means for generating a vertically scanning slit of of light, and projecting the latter towards the inspection zone; and a masking member containing a vertical slit being movable horizontally in the path of the scanning slit of light so as to occlude a portion of the latter and thereby resolve the vertical scanning slit of light into a spot beam scanning vertically and horizontally in the inspection zone. 16. Apparatus as recited in claim 15, in which there is provided; a drum adapted for rotation; a plurality of plane mirrors tangentially mounted on the drum; a light source adapted to project a slit of light on to the drum whereby each rotating mirror resoves the straight slit of light in a scanning slit of light; a cylindrical column below the drum having a vertical slot the axis of which column is perpendicular to the axis of the drum; a plurality of plane mirrors adjustably mounted within the column at an angle to the axis of the column whereby in use the scanning slit of light is reflected from each in turn of the plane mirrors so as to pass through the vertical slot in the column towards the inspection zone, the inclination of the reflective surface of each mirror to the vertical axis of the column is adjustable so that the angle of incidence of the spot beam of light on the container is the optimum angle for the detection of extraneous matter and cracks. 17. Apparatus as recited in claim 1, in which means is provided for scanning the spot beam of light vertically and horizontally in the inspection zone which means comprises; means for generating a vertically scanning slit of light, and projecting the latter towards the inspection zone; and a masking member containing a vertical slit being movable horizontally in the path of the scanning slit of light so as to occlude a portion of the latter and thereby resolve the vertical scanning slit of light into a spot beam scanning vertically and horizontally in the inspection zone. 18. Apparatus as recited in claim 17, in which there is provided; a drum adapted for rotation; a plurality of plane mirrors tangentially mounted on the drum; a light source adapted to project a slit of light on to the drum whereby each rotating mirror resolves the straight slit of light into a scanning slit of light; a cylindrical column below the drum having a vertical slot the axis of which column is perpendicular to the axis of the drum; a plurality of plane mirrors adjustably mounted within the column at an angle to the axis of the column whereby in use the scanning slit of light is reflected from each in turn of the plane mirrors so as to pass through the vertical slot in the column towars the inspection zone, the inclination of the reflective surface of each mirror to the vertical axis of the column is adjustable so that the angle of incidence of the spot beam of light on the container is the optimum angle for the detection of extraneous matter and cracks. 19. Apparatus for detecting the presence of extraneous matter and/or cracks in translucent containers when the color density and/or wall thickness of the translucent containers vary significantly from container to container, said apparatus comprising; an inspection zone; means for rotating a translucent container within the inspection zone; means for generating and vertically scanning a spot beam of light in the inspection zone; a light collection apparatus in the inspection zone; means for generating an electrical inspection signal corresponding to the amount of the light passing through the translucent container impinging on the light collection apparatus; means for synchronously generating a predetermined electrical signal; means for comparing said inspection signal with a predetermined electrical acceptance signal; means for obtaining prior to inspection of a container, a sample inspection signal at a predetermined vertical position of the spot beam of light; means to adjust the same sample inspection signal to an appropriate signal value while still maintaining a desired ratio between the inspection signal and the acceptance signal at that vertical position of the spot beam of light, the ratio of the original signal to the adjusted signal providing an adjustment factor; and means to adjust the inspection signal or acceptance signal by the adjustment factor during the inspection of the container. 20. Apparatus as recited in claim 19, in which the means for generating an electrical acceptance signal includes means to vary the value of the electrical acceptance signal as a function of the vertical position of the spot beam of light relative to the container, said means including a plurality of sensors for determining the vertical position of the spot beam of light, and a variable electrical signal output network connected to be controlled by said plurality of sensors. 21. Apparatus as recited in claim 20, in which there is provided means to amplify the said sample inspection signal to a predetermined electrical signal value and to amplify the inspection signal during inspection by the same gain used to amplify the sample inspection signal said means comprising: a variable gain amplifier; a sample and hold circuit to store the sample inspection signal operatively connected to the variable amplifier; a counter operatively connected to the gain circuit of the variable gain amplifier to vary the gain of the amplifier in discrete steps; a signal comparator operatively connected to the variable gain amplifier and to the counter, said signal comparator being set to a predetermined base signal, whereby when the signal from the variable gain amplifier exceeds the predetermined base signal, the comparator stops the counter thus holding the gain of the amplifier; and means for producing an electrical rejection signal when with the variable gain amplifier set to maximum gain the comparator does not operate. 22. Apparatus as recited in claim 21, in which ambient light correction means is provided for determining prior to inspection the electrical signal corresponding to the effect of ambient light impinging on the light collection apparatus, and in which said ambient light signal is electrically subtracted from the inspection signal during inspection of the translucent container. 23. Apparatus as recited in claim 22, in which means is provided for scanning the spot beam of light vertically and horizontally in the inspection zone which means comprises; means for generating a vertically scanning slit of light, and projecting the latter towards the inspection zone; and a masking member containing a vertical slit being movable horizontally in the path of the scanning slit of light so as to occlude a portion of the latter and thereby resolve the vertical scanning slit of light into a spot beam scanning vertically and horizontally in the inspection zone. 24. Apparatus as recited in claim 23, in which there is provided; a drum adapted for rotation; a plurality of plane mirrors tangentially mounted on the drum; a light source adapted to project a slit of light on to the drum whereby each rotating mirror resolves the straight slit of light into a scanning slit of light; a cylindrical column below the drum having a vertical slot the axis of which column is perpendicular to the axis of the drum; a plurality of plane mirrors adjustably mounted within the column at an angle to the axis of the column whereby in use the scanning slit of light is reflected from each in turn of the plane mirrors so as to pass through the vertical slot in the column towards the inspection zone, the inclination of the reflective surface of each mirror to the vertical axis of the column is adjustable so that the angle of incidence of the spot beam of light on the container is the optimum angle for the detection of extraneous matter and cracks. 25. Apparatus as recited in claim 22, in which the ambient light correction means comprises: a differential amplifier; means for feeding the inspection signal to the differential amplifier; a sample and hold circuit operatively connected to the light collection apparatus for holding an electrical signal corresponding to the ambient light impinging on the light collection apparatus prior to inspection; and means for feeding the said ambient light signal to the differential amplifier whereby the signal output of the amplifier is the electrical difference between the inspection signal and the ambient light signal. 26. Apparatus as recited in claim 21, in which means is provided for scanning the spot beam of light vertically and horizontally in the inspection zone which means comprises; means for generating a vertically scanning slit of of light, and projecting the latter towards the inspection zone; and a masking member containing a vertical slit being movable horizontally in the path of the scanning slit of light so as to occlude a portion of the latter and thereby resolve the vertical scanning slit of light into a spot beam scanning vertically and horizontally in the inspection zone. 27. Apparatus as recited in claim 26, in which there is provided; a drum adapted for rotation; a plurality of plane mirrors tangentially mounted on the drum; a light source adapted to project a slit of light on to the drum whereby each rotating mirror resolves the straight slit of light into a scanning slit of light; a cylindrical column below the drum having a vertical slot the axis of which column is perpendicular to the axis of the drum; a plurality of plane mirrors adjustably mounted within the column at an angle to the axis of the column whereby in use the scanning slit of light is reflected from each in turn of the plane mirrors so as to pass through the vertical slot in the column towards the inspection zone, the inclination of the reflective surface of each mirror to the vertical axis of the column is adjustable so that the angle of incidence of the spot beam of light on the container is the optimum angle for the detection of extraneous matter and cracks. 28. Apparatus as recited in claim 20, in which means is provided for scanning the spot beam of light vertically and horizontally in the inspection zone which means comprises; means for generating a vertically scanning slit of light, and projecting the latter towards the inspection zone; and a masking member containing a vertical slit being movable horizontally in the path of the scanning slit of light so as to occlude a portion of the latter and thereby resolve the vertical scanning slit of light into a spot beam scanning vertically and horizontally in the inspection zone. 29. Apparatus as recited in claim 28, in which there is provided; a drum adapted for rotation; a plurality of plane mirrors tangentially mounted on the drum; a light source adapted to project a slit of light on to the drum whereby each rotating mirror resolves the straight slit of light into a scanning slit of light; a cylindrical column below the drum having a vertical slot the axis of which column is perpendicular to the axis of the drum; a plurality of plane mirrors adjustably mounted within the column at an angle to the axis of the column whereby in use the scanning slit of light is reflected from each in turn of the plane mirros so as to pass through the vertical slot in the column towards the inspection zone, the inclination of the reflective surface of each mirror to the vertical axis of the column is adjustable so that the angle of incidence of the spot beam of light on the container is the optimum angle for the detection of extraneous matter and cracks. 30. Apparatus as recited in claim 20, in which ambient light correction means is provided for determining prior to inspection the electrical signal corresponding to the effect of ambient light impinging on the light collection apparatus, and in which said ambient light signal is electrically subtracted from the inspection signal during inspection of the translucent container. 31. Apparatus as recited in claim 30, in which the ambient light correction means comprises: a differential amplifier; means for feeding the inspection signal to the differential amplifier; a sample and hold circuit operatively connected to the light collection apparatus for holding an electrical signal corresponding to the ambient light impinging on the light collection apparatus prior to inspection; and means for feeding the said ambient light signal to the differential amplifier whereby the signal output of the amplifier is the electrical difference between the inspection signal and the ambient light signal. 32. Apparatus as recited in claim 30, in which means is provided for scanning the spot beam of light vertically and horizontally in the inspection zone which means comprises; means for generating a vertically scanning slit of light, and projecting the latter towards the inspection zone; and a masking member containing a vertical slit being movable horizontally in the path of the scanning slit of light so as to occlude a portion of the latter and thereby resolve the vertical scanning slit of light into a spot beam scanning vertically and horizontally in the inspection zone. 33. Apparatus as recited in claim 32, in which there is provided; a drum adapted for rotation; a plurality of plane mirrors tangentially mounted on the drum; a light source adapted to project a slit of light on to the drum whereby each rotating mirror resolves the straight slit of light into a scanning slit of light; a cylindrical column below the drum having a vertical slot the axis of which column is perpendicular to the axis of the drum; a plurality of plane mirrors adjustably mounted within the column at an angle to the axis of the column whereby in sue the scanning slit of light is reflected from each in turn of the plan mirrors so as to pass through the vertical slot in the column towards the inspection zone, the inclination of the reflective surface of each mirror to the vertical axis of the column is adjustable so that the angle of incidence of the spot beam of light on the container is the optimum angle for the detection of extraneous matter and cracks. 34. Apparatus as recited in claim 19, in which there is provided, means to amplify the said sample inspection signal to a predetermined electrical signal value and to amplify the inspection signal during inspection by the same gain used to amplify the sample inspection signal said means comprising: a variable gain amplifier; a sample and hold circuit to store the sample inspection signal operatively connected to the variable gain amplifier; a counter operatively connected to the gain circuit of the variable gain amplifier to vary the gain of the amplifier in discrete steps; a signal comparator operatively connected to the variable gain amplifier and to the counter, said signal comparator being set to a predetermined base signal, whereby when the signal from the variable gain amplifier exceeds the predetermined base signal, the comparator stops the counter thus holding the gain of the amplifier; and means for producing an electrical rejection signal when with the variable amplifier set to maximum gain the comparator does not operate. 35. Apparatus as recited in claim 34, in which means is provided for scanning the spot beam of light vertically and horizontally in the inspection zone which means comprises; means for generating a vertically scanning slit of light, and projecting the latter towards the inspection zone; and a masking member containing a vertical slit being movable horizontally in the path of the scanning slit of light so as to occlude a portion of the latter and thereby resolve the vertical scanning slit of light into a spot beam scanning vertically and horizontally in the inspection zone. 36. Apparatus as recited in claim 35, in which there is provided; a drum adapted for rotation; a plurality of plane mirrors tangentially mounted on the drum; a light source adapted to project a slit of light on to the drum whereby each rotating mirror resolves the straight slit of light into a scanning slit of light; a cylindrical column below the drum having a vertical slot the axis of which column is perpendicular to the axis of the drum; a plurality of plane mirrors adjustably mounted within the column at an angle to the axis of the column whereby in use the scanning slit of light is reflected from each in turn of the plane mirrors so as to pass through the vertical slot in the column towards the inspection zone, the inclination of the reflective surface of each mirror to the vertical axis of the column is adustable so that the angle of incidence of the spot beam of light on the container is the optimum angle for the detection of extraneous matter and cracks. 37. Apparatus as recited in claim 34, in which ambient light correction means is provided for determining prior to inspection the electrical signal corresponding to the effect of ambient light impinging on the light collection apparatus, and in which said ambient light signal is electrically added to the acceptance signal or subtracted from the inspection signal during inspection of the translucent container. 38. Apparatus as recited in claim 37, in which the ambient light correction means comprises: a differential amplifier; means for feeding the inspection signal to the differential amplifer; a sample and hold circuit operatively connected to to the light collection apparatus for holding an electrical signal corresponding to the ambient light impinging on the light collection apparatus prior to inspection; and means for feeding the said ambient light signal to the differential amplifier whereby the signal output of the amplifier is the electrical difference between the inspection signal and the ambient light signal. 39. Apparatus as recited in claim 37, in which means is provided for scanning the spot beam of light vertically and horizontally in the inspection zone which means comprises; means for generating a vertically scanning slit of light, and projecting the latter towards the inspection zone; and a masking member containing a vertical slit being movable horizontally in the path of the scanning slit of light so as to occlude a portion of the latter and thereby resolve the vertical scanning slit of light into a spot beam scanning vertically and horizontally in the inspection zone. 40. Apparatus as recited in claim 39, in which there is provided; a drum adapted for rotation; a plurality of plane mirrors tantentially mounted on the drum; a light source adapted to project a slit of light on to the drum whereby each rotating mirror resolves the straight slit of light into a scanning slit of light; a cylindrical column below the drum having a vertical slot the axis of which column is perpendicular to the to the axis of the drum; a plurality of plane mirrors adjustably mounted within the column at an angle to the axis of the column whereby in use the scanning slit of light is reflected from each in turn of the plane mirrors so as to pass through the vertical slot in the column towards the inspection zone, the inclination of the reflective surface of each mirror to the vertical axis of the column is adjustable so that the angle of incidence of the spot beam of light on the container is the optimum angle for the detection of extraneous matter and cracks. 41. Apparatus as recited in claim 19, in which ambient light correction means is provided for determining prior to inspection the electrical signal corresponding to the effect of ambient light impinging on the light collection apparatus, and in which said ambient light signal is electrically subtracted from the inspection signal during inspection of the translucent container. 42. Apparatus as recited in claim 41, in which the ambient light correction means comprises: a differential amplifier; means for feeding the inspection signal to the differential amplifier; a sample and hold circuit operatively connected to the light collection apparatus for holding an electrical signal corresponding to the ambient light impinging on the light collection apparatus prior to inspection; and means for feeding the said ambient light signal to the differential amplifier whereby the signal output of the amplifier is the electrical difference between the inspection signal and the ambient light signal. 43. Apparatus as recited in claim 41, in which means is provided for scanning the spot beam of light vertically and horizontally in the inspection zone which means comprises; means for generating a vertically scanning slit of light, and projecting the latter towards the inspection zone; and a masking member containing a vertical slit being movable horizontally in the path of the scanning slit of light so as to occlude a portion of the latter and thereby resolve the vertical scanning slit of light into a spot beam scanning vertically and horizontally in the inspection zone. 44. Apparatus as recited in claim 43, in which there is provided; a drum adapted for rotation; a plurality of plane mirrors tangentially mounted on the drum; a light source adapted to project a slit of light on to the drum whereby each rotating mirror resolves the straight slit of light into a scanning slit of light; a cylindrical column below the drum having a vertical slot the axis of which column is perpendicular to the axis of the drum; a plurality of plane mirrors adjustably mounted within the column at an angle to the axis of the column whereby in use the scanning slit of light is reflected from each in turn of the plane mirrors so as to pass through the vertical slot in the column towards the inspection zone, the inclination of the reflective surface of each mirror to the vertical axis of the column is adjustable so that the angle of incidence of the spot beam of light on the container is the optimum angle for the detection of extraneous matter and cracks. 45. Apparatus as recited in claim 19, in which means is provided for scanning the spot beam of light vertically and horizontally in the inspection zone which comprises; means for generating a vertically scanning slit of light, and projecting the latter towards the inspection zone; and a masking member containing a vertical slit being movable horizontally in the path of the scanning slit of light so as to occlude a portion of the latter and thereby resolve the vertical scanning slit of light into a spot beam scanning vertically and horizontally in the inspection zone. 46. Apparatus as recited in claim 45, in which there is provided; a drum adapted for rotation; a plurality of plane mirrors tangentially mounted on the drum; a light source adapted to project a slit of light on to the drum whereby each rotating mirror resolves the straight slit of light into a scanning slit of lights; a cylindrical column below the drum having a vertical slot the axis of which column is perpendicular to the axis of the drum; a plurality of plane mirrors adjustably mounted within the column at an angle to the axis of the column whereby in use the scanning slit of light is reflected from each in turn of the plane mirrors so as to pass through the vertical slot in the column towards the inspection zone, the inclination of the reflective surface of each mirror to the vertical axis of the column is adjustable so that the angle of incidence of the spot beam of light on the container is the optimum angle for the detection of extraneous matter and cracks. 47. A method for detecting the presence of extraneous matter and/or cracks in translucent containers said method including the steps of: moving the translucent container into an inspection zone; rotating the container about its vertical axis within the inspection zone; vertically scanning the container within the inspection zone with a spot beam of light; collecting the light transmitted through the container in the inspection zone; generating an electrical inspection signal corresponding the intensity of light passing through the container; providing an acceptance signal which is a function of the vertical position of the spot beam of light relative to the container; comparing said inspection with signal with said acceptance signal; and generating a rejection signal when the intensity of light passing through the translucent container is below a predetermined value measured by said acceptance signal. 48. A method as recited in claim 47, in which the following additional steps are carried out; obtaining an electrical signal corresponding to the ambient light prior to inspection; and subtracting said ambient light signal from the inspection signal during inspection of the translucent container. 49. A method as recited in claim 47, in which the following steps prior to inspection are carried out; a sample inspection signal on a predetermined vertical position of the spot beam of light relative to the container is obtained; the said sample inspection signal is adjusted to an appropriate signal value, said adjustment determining an adjustment factor which is the ratio of the original to the adjusted signal, such as to maintain a desired ratio between the inspection signal and the acceptance signal; adjusting the inspection signal or acceptance signal by the adjustment factor during the inspection of the container. 50. A method as recited in claim 49, in which the following additional steps are carried out; obtaining an electrical signal corresponding to the ambient light prior to inspection; and subtracting said ambient light signal from the insepction signal during inspection of the translucent container. 51. A method as recited in claim 47, in which the acceptance signal is generated by detecting the vertical position of the spot beam of light relative to the container, and by generating an electrical signal corresponding to the vertical position of the spot beam of light which latter electrical signal activates a variable electrical signal output network. 52. A method as recited in claim 51, in which the following additional steps are carried out; obtaining an electrical signal corresponding to the ambient light prior to inspection; and subtracting said ambient light signal from the inspection signal during inspection of the translucent container. 53. A method as recited in claim 51, in which the following steps prior to inspection are carried out; a sample inspection signal on a predetermined vertical position of the spot beam of light relative to the container is obtained; the said sample inspection signal is adjusted to an appropriate signal value, said adjustment determining an adjustment factor which is the ratio of the original to the adjusted signal, such as to maintain a desired ratio between the inspection signal and the acceptance signal; adjusting the inspection signal or acceptance signal by the adjustment factor during the inspection of the container. 54. A method as recited in claim 53, in which the following additional steps are carried out; obtaining an electrical signal corresponding to the ambient light prior to inspection; and subtracting said ambient light signal from the inspection signal during inspection of the translucent container. Other info: Inventors: O'Connor, Bartholomew John (Churchtown, EI) Application Number: 483350 Filing Date: 1974-06-26 Publication_date: 1976-03-02 Assignee: Talcoma Teoranta (Dublin, EI) Primary Class(es): 250/223B 62/51.1, 209/526, 250/224 Other Classes: US Patent Ref:
Other Refs:
Primary Examiner: Lawrence, James W. Assistant Examiner: LaRoche, E. R. Attorney: Sughrue, Rothwell, Mion, Zinn & Macpeak |
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