Classifying – separating – and assorting solids – Sorting special items – and certain methods and apparatus for... – Condition responsive means controls separating means
Reexamination Certificate
2000-04-28
2003-01-14
Nguyen, Tuan N. (Department: 3653)
Classifying, separating, and assorting solids
Sorting special items, and certain methods and apparatus for...
Condition responsive means controls separating means
C209S587000, C209S639000, C209S932000
Reexamination Certificate
active
06506991
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method of sorting waste paper of different grades and conditions, in which at least one area of the surface of various waste paper fractions or pieces, such as paper and board, which are lying on at least one sorting belt, is irradiated such that the radiation reflected from the pieces of waste paper is registered. Thereafter, the pieces of waste paper are assigned to a specific waste paper fraction on the basis of the data which is determined from the reflected radiation. The pieces are subsequently sorted appropriately based upon this data. The invention also relates to an apparatus which practices this method.
2. Discussion of Background Information
A known method and apparatus are disclosed by the Registered Design specification AT 001 959 U1, application number GM 246/97, and this document is expressly incorporated by reference it its entirety. According to AT 001 959 U1, the fractions or pieces are separated on a sorting belt. Moreover, the pieces are irradiated by radiation sources, such as a light source. Additionally, the reflected radiation is registered by evaluation units and the pieces of waste paper are thereafter assigned to a specific fraction which is picked up by pick-up devices and thereafter deposited on a predetermined deposit location.
In this conventional method, the reflected radiation is picked up by a camera and the specific features, e.g., the different wavelengths of the reflected radiation, of the area picked up are compared with stored classifiers which can be learned. However, this conventional method and apparatus cannot efficiently and adequately sort paper fractions. Additionally, it has a relatively high error rate in separating the types fractions.
SUMMARY OF THE INVENTION
The invention therefore provides a system with a low sorting error rate and provides a quick, simple method and a corresponding apparatus for sorting waste paper efficiently.
The invention takes advantage of the intensity differences of the radiation which is reflected from adjacent subareas of the area viewed. These intensity differences are accordingly determined. Moreover, by using the intensity distribution inherent to each waste paper fraction, better assignment to a specific fraction can be achieved in utilizing the invention.
One aspect of the invention provides that each of the equally large subareas is assigned an intensity value. Then, the relative difference between the intensity values of adjacent subareas is determined and the sum of these intensity differences is formed for the area viewed. For example, a narrow rectangular strip may be imaged and subdivided into equally large squares, which are also referred to as pixels. Each pixel is accordingly assigned a specific intensity value. Then, for each pair of pixels, most particularly adjacent pixels, the difference in the intensity values is formed or determined. Thereafter, all the differences are subsequently summed.
In this case, provision can be made for the pieces of waste paper to be assigned to a paper fraction if the sum of the intensity differences exceeds a limiting value or threshold. Thus, for the area viewed, if high intensity differences occur between the pixels, that is say, for example, a light/dark change occurs frequently, it can be assumed that this piece is one having close printing (e.g., small text). As a result of these light/dark differences, the sum of the intensity differences will be correspondingly large.
It should be noted that the limiting value for the paper fraction may be made adjustable. Moreover, this limiting value may be established beforehand. Alternatively, it may be established empirically by conducting numerous trials.
In a similar way, provision may be made for the pieces of waste paper to be assigned to the board fraction. In this case, the sum of the intensity differences will generally fall at or below a limiting value. This is because board generally has very little if any printing for the area viewed. Accordingly, with little or no intensity differences occurring between adjacent pixels, the sum of the intensity differences will be correspondingly small. Again, as described above, the limiting value may be made adjustable and/or determined by trial and error.
For the purpose of separating two distinct fractions, e.g., paper and board, the two aforementioned limiting values may coincide.
According to the invention, an area is advantageously irradiated with visible light. This allows for the use of standard radiation sources and standard evaluation devices which are commercially available. As a result, this design can be made cost-effective. However, infrared radiation may also be utilized with frequencies in the close infrared, e.g., having a range which includes wavelengths from approximately 780 nanometers to approximately 2,000 nanometers. Moreover, radiation in the X-ray range may also be utilized.
A further refinement of the method provides that the method of sorting is additionally used in which the wavelength of the reflected radiation is taken into account. By utilizing a combination of the method according to the invention with the method shown in AT 001 959 U1, the accuracy of the sorting can be increased still further.
In this case, for example, the procedure is such that firstly, using the method in which the wavelength of the reflected radiation is determined, an attempt is made to assign the piece of waste paper to a specific fraction. This is the part of the combination which utilizes the system disclosed in AT 001 959 U1. However, in the event that a piece of waste paper cannot be assigned uniquely to a specific fraction, use may be subsequently made of the method of sorting in which the intensity differences in the reflected radiation are determined. This is the part of the combination which utilizes the features of the invention. By combining these systems, it is possible to take full advantage of the benefits of the two methods. In particular, this combination makes it possible for pieces of waste paper which, according to the method of AT 001 959 U1 could be both paper and board (such as specific newsprint, whose color is similar to that of board) to be assigned uniquely.
The invention utilizes a system or apparatus for implementing the method of sorting waste paper of different grade and conditions. Moreover, this apparatus processes various waste paper fractions, such as paper and board.
The apparatus includes at least one sorting belt for conveying the pieces of waste paper lying thereon. Above the sorting belt there is arranged at least one radiation source, for irradiating at least one area of the sorting belt, and at least one evaluation device. The evaluation device registers the radiation reflected from the pieces of waste paper of the individual fractions and assigns the pieces of waste paper to a specific waste paper fraction on the basis of the data determined. Moreover, the radiation source and the evaluation device have at least one sorting device arranged downstream in the conveying direction of the sorting belt. The apparatus provides that at least one part of an evaluation device, which determines intensity differences of the radiation which is reflected from adjacent subareas of the area viewed, is arranged above the sorting belt.
In a simple and cost effective embodiment of the invention, the radiation source radiates visible light. In this case, provision may be made for the evaluation device to utilize a camera.
Additionally, the method according to the invention may be executed quickly and with little outlay with regard to data processing, if the evaluation device utilizes a line-scan type camera. This device can be utilized to scan a narrow strip of the area of interest. In this design, the intensity differences may be determined for only a series of subareas.
In one embodiment, the sorting device utilizes at least one device for producing a flow of air. This design allows for the waste paper fraction to be sorted out without mechanical pick-u
Eixelberger Rainer
Friedl Peter
Gschweitl Karlheinz
Binder & Co. Aktiengesellschaft
Greenblum & Bernstein P.L.C.
Nguyen Tuan N.
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