Introduction
To perceive the rationale for the inspection of the bottles’ colour, we recommended to take a look at the figure on right side. That is what a Customer considered “a bottle format”.
In this conditions the Bottler’s production face any or more of these negative effects:
The differences of colour between bottles add false rejects and reduce the defects' detection ratio
- bottles of the wrong colour, sometimes originating by a Competitor, reaching the Market labelled with the Bottler’s label and beverage.
- huge false rejects originating by the EBI’s base and external sidewall inspections;
- macroscopic and dangerous defects passing to the Market, a typical case encountered when the bottle has a colour much darker than that for which the bottle format has been commissioned in the EBI.
Technology
The signals incoming by three separate channels, each one corresponding to a fundamental colour, are processed to deduce the bottle’s glass colour. The couple of yellow colour vertical lines are the inspection window, the range of distances measured in millimetres equivalent to Encoder pulses. In the vertical axe of the diagram they appear, digitized in a scale of 4096 bits, the signals’ amplitudes. In the example shown, a cap has been measured thru all three channels with approximately the same amplitude ~1380 bits. The image setup in the meantime specifying a “good colour 1” implies that all bottles whose chromatic mix similar to this one shall be considered correctly coloured. Where “correctly” means their colour is coherent with the currect production
A solution pass thru the control of the colour of each one bottle directly in the Empty Bottle Inspector, where they present themselves yet washed and with a minimum amount of labels. Colour control made illuminating with a source of known spectrum, typically a halogen lamp, the upper half of the bottle sidewall. A portion of the light, after having been refracted by the glass, gets out on the opposite side of the bottle. Finally enters the lens of a trichromatic detector part of the Colour inspection. A device with three separate channels, referred to the familiar fundamental colours red, green and blue. The signal in the outfeed of each one channel is separately amplified and later digitised and processed, comparing the digitised value with upper and lower limits set during the commissioning. As an example, refer to the graphic below on right side:
- a couple of yellow colour vertical lines represents the inspection window, the range of distances in the Inspector's Shifting-Register, where the three chromatic channels are evaluated;
- red colour the red chroma signal, whose grey level is normalized (0 - 4096);
- blue colour the blue chroma signal amplitude, whose grey level is normalized (0 - 4096);
- green colour the green chroma signal, whose grey level is normalized (0 - 4096);
- white colour their superimposed amplitude, whose grey level is normalized (0 - 4096).
Bottles whose tri-chromatic mix is out of each one of the three allowed ranges, shall be rejected. In the example shown, a cap has been measured thru all three channels with approximately the same amplitude ~1380 bits. The image setup in the meantime specifying a “good colour 1” implies that all bottles whose chromatic mix similar to this one shall be considered correctly coloured. Where “correctly” means their colour is coherent with the currect production. In the figure below, the black colour square box in the red circle hosts the tri-chromatic sensor assemble. Not visible, on the opposite side with respect to the sensor, the 12 VDC halogen lamp used as a spectral reference. The Sun in some special times of the day, may influence the thrichromatic sensor measurements, adding yellow colour centered values implying false rejects. In these cases, it results necessary to shield the system.
Links to other pages:
Classification on base of the kind of container Empty Bottle Inspectors (EBIs) and the related measurements whose goal is a binary classification (collectively named inspections), are a category making a particularly sensitive activity: to protect final consumers' health, assuring beverages' safety in the Food and Beverage Packaging Lines. …
Rotary-Linear EBI ComparisonRotary EBIThe Empty Bottle Inspectors of the past were always and only Rotary Machines. The industries which first started to design and produce them and those which adopted them, were all US-based and specialized in the production of glass bottles. …
Introduction When discussing elsewhere the High Frequency fill level inspection, we also examined the complex mechanism of interaction between the High Frequency (HF) electromagnetic waves (3 - 30 MHz) and polar liquids like water. …
Introduction It is a fact: when bottles are urgently needed, also glass returnable bottles born to host beer or mineral water, can fulfill their basic purpose of container for liquids of completely different nature. …
Introduction Base inspection is the most important at all and also the first historically created for EBIs. In the start, it was applied to small inspectors used by glass bottles Producers. It is always present in the Empty Bottle Inspectors, as a minimum standard, jointly with a few others like the High Frequency Residual Liquid control and the Finish inspection.
A common PET bottle as visible with (right side) and without (left side) polarising filtering. At right side, cellophane in the stripes around the bottle rotates the light polarization vector (  …
Introduction The term “finish” originates with the mouth-blown bottle production process where the last step in completing a finished bottle was to finish its lip. Today, the lip or finish is the first forming step in the bottle making process. …
Operative principleThe operative principle of the Finish inspection is applied, in a similar way, to the more complex case of check of the status of the glass threads. In this case, light is generated by an illuminator on top of the finish. …
In the Linear Glass Returnable Empty Bottle Inspectors, External Sidewall Inspection may be performed adopting one or two CCD-cameras. We’ll treat in the following the application with two CCD-cameras: single-camera applications are not satisfactory, covering only < 80 % of the external surface of the bottles.
Why Inner Sidewall InspectionThe inner surface of the bottle may host larvae, insects and other low-contrast foreign objects whose detection, as seen by the External Sidewall is nearly impossible. …
IntroductionThey exist defects no Bottle Washer shall never remove, whatever the duration of its cycles, the amount of caustic soda or temperature of the water. Between these:Paint, internal or external;…
IntroductionScuffing is a memory of the many passages of the returnable bottle thru the Bottling Line, mainly of the wearing of its external sidewalls after friction with other adiacent bottles. …
Infeed ChecksEmpty Bottle Inspectors always need to be protected by prior controls and rejector, to prevent damages implicit in their operation. Dammages originated by: fallen bottles, inclined bottles, …
- EBI Classification
- Linear and Rotary EBIs
- High Frequency residual Liquid control
- IR Residual liquid control
- Base inspection, opaque defects
- Base inspection, transparent defects
- Finish inspection, crown cork
- Finish inspection, broken Thread
- External sidewall inspection, for opaque defects
- Inner sidewall inspection for opaque defects
- Mineral ring inspection
- Scuffing inspection
- Infeed checks
- Colour inspection
- Closure inspection with digital photoscanners
Contact
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