Abstract:
A method and device for detection and identification of liquid, solid, and gaseous foreign substances of beverages and/or beverage residues in re-usable bottles, especially in plastic bottles and other containers. Electromagnetic radiation traverses the walls of the bottles and containers at least once, and by areas of residual liquid, areas with liquid films, solid films on the inside wall and areas with contamination inside the wall are detected by the electromagnetic radiation.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a method and device for detecting and identifying harmful substances in re-useable bottles or containers for liquid, solid and gaseous containments. 
     BACKGROUND OF THE INVENTION 
     The testing of reusable bottles and reusable containers for liquid, solid, and gaseous contaminants is an important technical problem, especially since the introduction of plastic bottles and plastic containers, since the harmful substances such as poisons diffuse into the wall material and, upon refilling with the product in question, for example lemonade, cola, fruit juice, etc., have an adverse affect on the taste. 
     In German P 41 21 429.3, an efficient method and devices are proposed for solving the problem of harmful substances by using gas samples drawn from the bottle or the container above the level of the liquid. One disadvantage of this approach resides in the fact that materials with extremely low partial pressures, such as, for example, high-boiling vegetable oils, hydraulic oils, inks, water-soluble dyes, naphthalene, etc. cannot be detected reliably if at all. 
     In U.S. Pat. No. 4,858,768, a method is proposed for investigating, in detail, a liquid drawn from the bottle or container to determine whether the liquid corresponds to the original product in the bottle or container and, if not, rejecting the bottle or container from the refilling process. This is uneconomical since re-usable bottles and containers very rarely return with original product to the filling plant. Consequently, a number of bottles are unjustifiably rejected because many fermentation products, rinsing with water by the consumer, drying out, etc alter the composition of the original product but would not cause the bottle or container to be termed contaminated. In addition, the sole examination of the residual fluid or residue contained in the bottle or container as intended in U.S. Pat. No. 4,858,768 does not solve the problem since harmful substances adsorbed in the walls of the bottle or container would not be detected. 
     SUMMARY OF THE INVENTION 
     The aim of the present invention is to provide both a method and a device which, in addition to contaminant analysis in the respective residual fluid, conducts the same analysis on the wall of the bottle or container as well as in a gas chamber of the bottle or container. In addition, the method according to the invention permits a harmful-substance analysis of liquid films located on the wall, for example oil films, films of cleaning agents, detergents, etc., as well as a harmful-substance analysis of the dried product, in other words, the product film, as well as solid films for example thin layers of inks, paints, adhesives, waxes, cosmetic products, etc. 
     According to the invention, the bottle or container to be investigated is lrradiated with electromagnetic radiation of a suitable wavelength, within the total interval between the wavelengths of 200 nm and 10 cm. The wavelength ranges were selected to ensure high permeability of the bottle wall to electromagnetic radiation. The direction of the electromagnetic radiation is adjusted according to the invention in such fashion that both the bottom of the bottle or container as well as the walls of the bottle or container are traversed by the electromagnetic radiation. From the wavelength dependence of the attenuation of the electromagnetic radiation, with consideration according to the invention of the electromagnetic radiation transmission in the material composing the wall of the bottle or container, the respective contaminant in the residual fluid and/or in the gas chamber is detected and analyzed on line. Furthermore, it is simultaneously determined according to the invention, what product was originally used to fill the container or bottle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described in greater detail with reference to the accompanying drawings, wherein: 
     FIG. 1 is a schematic view of an overall arrangement for harmful-substance detection and real-time harmful-substance analysis of residual fluid in a wall of a bottle or container and analysis of liquid solid films on an inside wall of the container in a system in accordance with the present invention; 
     FIG. 2 is a graphical illustration of results of a real-time harmful-substance analysis and/or real-time residual-product analysis in reusable polyethylene beverage bottles. 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings and, more particularly, to FIG. 1, according to this figure a bottle or container 11 is advanced by a transport device 12 in a filling line. The transport device is adapted to execute a rotational movement around an axis 13 or any other movement, for example, a linear movement. Alternatively, a guide surface 15, which, in the embodiment of FIG. 1 is stationary, may serve as a conveyor belt for transporting bottles or containers. 
     A real-time material analysis is accomplished by an on-line spectrometer 7 for electromagnetic radiation with a downstream signal evaluation unit 8. Both the spectrometer 7 and signal evaluation unit 8 are described in detail in P 41 21 429.3 with regard to both their construction and their function. The on-line spectrometer 7 is preferably designed for an ultraviolet/visible region and/or for a near and/or medium infrared region of the electromagnetic spectrum. A source 1 generated electromagnetic radiation and transmits the radiation energy through a fiber bundle 2 of quartz glass or of infrared-transparent fluorine-special compounds to a focusing element or lens 3. The lens 3 generates an approximately parallel beam 4 that traverses the bottle or container 11 in a vicinity of a champagne bottom and is focused by a focusing element or lens 5 on a second fiber bundle 6 to reach an input of the on-line spectrometer 7. 
     Alternatively, a second system may be installed along a line 14 or along other directions not shown in FIG. 1. In a preferred embodiment, the beam direction may also run along a line 27. The entire system according to FIG. 1, in addition to real-time analysis of the residual fluid 9 contained in the bottle or container 11 may be used especially for real-time analysis or liquid/solid films 10 on an interior or inside wall of the bottle or container 11. Additionally, molecules of harmful substances 18, deposited by fusion processes in the wall of the bottle or container 11, are identified. 
     In order to obtain the largest possible amount of residual fluid in the investigation area, provision can advantageously be made for the bottle or container 11 to be tilted slightly up to a maximum of 45°. This may be performed by a suitable construction of a holder on a transport device 12 engageable with a neck of the bottle or container 11. 
     In order to avoid contamination during the rough operation to which the focusing elements or lens 3, 5 are necessarily exposed, the focusing elements or lens 3, 5 are flushed by nozzles 16 which deliver a jet of clean air 17. As a result, the condensation of harmful substances, deposition of dust particles, and condensation of water vapor on the focusing element or lens 3, 5 and other components is prevented. 
     The results of the real-time analysis according to the invention using the complete system shown in FIG. 1 are shown in FIGS. 2a, 2b, with FIG. 2a depicting wavelength dependencies of the logarithmic attenuation, the so-called extinction E of the electromagnetic radiation for a new uncontaminated bottle or container 24 as well as for dangerous or undesirable contaminations of residual fluid 9 with harmful substances. The wall of the bottle or container 11 and harmful substance films 10 are plotted. Harmful substances shown include a nickel bath galvanic solution 23, ink 26, urine 19, gentle-purpose cleaners 27, and a disinfectant NaCLo 28 as examples. 
     The typical functional curves for each substance, obtained using the signal evaluation 8, permit clear detection and identification of the harmful substances and especially the functions appropriately plotted in FIG. 2b as well for foodstuffs such as cola 20, strawberry juice 22, orange lemonade 21, vegetable oil 18, and currant juice 23. The clearly characteristic function curves for each substance permit selective determination of the individual substances, in other words, a distinction between poisonous, undesirable, and desirable substances and their concentrations, even when several poisons or poisons and foods are present in a mixture. If mineral water bottles are investigated, only those bottles are considered good that contain water exclusively as a residual liquid, and, for all other residual liquids, including juices, lemonade, or the like, rejection is performed since such contents, even after cleaning of the bottles or containers, can cause an aftertaste in bottles or containers that are refilled with mineral water. 
     This evaluation and/or analysis is performed on the basis of the functions shown in FIGS. 2a and 2b (18, 19, 20, 21, 22, 23, 24) by a mathematical superimposition of this function on the respective result function obtained according to FIG. 1 from the system. 
     Conventional methods are utilized for the purpose of performing the evaluation and/or analysis on the basis of the function shown in FIG. 2, in other words, the result function E is determined in accordance with the following relationship: 
     
         E (λ)=a.sub.1 E.sub.1 (λ)+a.sub.2 E.sub.2 (λ)+. . . +a.sub.n E.sub.n (λ), 
    
     where (λ)=the wavelength, 
     E 1  (λ)=the functional curve for the substance, and 
     A 1  =parameters providing concentration values for the respective substances.