Glass color sensor unit

Apparatus for measuring the color of glass, particularly pieces of broken glass relies upon simultaneously measuring the glass transmission in different spectral regions. The glass pieces travel along a conveying path between a light source and a light sensor containing a plural number of optical filters and groups of photoelectric detectors. The groups of photoelectric detectors are disposed at an end face of respective substantially cylindrical tubes. Tube axes enclose an angle and intersect in a conveying plane defined by the conveying path. The optical filters have different spectral transmission regions. Optical lens systems are retained intermediate the respective groups of photoelectric detectors and an opposite end face of the respective tubes. Each optical lens system images the conveying plane at the associated group of photoelectric detectors.

CROSS-REFERENCE TO RELATED APPLICATION 
This application is related to the commonly assigned, copending U.S. patent 
application Ser. No. 08/035,480, filed Mar. 24, 1993, entitled "Method and 
Device of Sorting Bulk Material". 
BACKGROUND OF THE INVENTION 
The present invention relates to a new and improved construction of 
apparatus for measuring the color of glass, particularly broken glass. 
In its more specific aspects, the present invention particulaly relates to 
a new and improved construction of apparatus for measuring the color of 
glass, particularly broken glass pieces and which apparatus includes means 
for simultaneousy measuring the transmission of the glass pieces in 
different spectral regions. The glass pieces are passed along a conveying 
path which extends between a light source and a light sensor or sensor 
head containing a plural number of optical filters and associated 
photoelectric detectors. 
A sorting apparatus such as known, for example, from U.S. Pat. No. 
3,980,180, granted Sep. 14, 1976, includes a belt conveyor receiving 
single glass particles in depressions which are aligned with apertures 
provided in the belt conveyor. The belt conveyor passes a sensing station 
containing light sources on one side of the belt conveyor and light 
detectors located on the opposite side of the belt conveyor so that light 
transmitted by the glass particles is detected. The light sources and the 
light detectors are selected so as to respectively emit and sense light of 
a narrow band width in a manner such that the intensity of the light 
transmitted by the glass particles is indicative of the color of the glass 
particles. The sensing station is followed in the conveying direction of 
the belt conveyor by a separating station which is provided with 
corresponding sensing means and compressed air nozzles producing an air 
jet for blowing away into a collecting container any glass particles 
having a predetermined color. A number of such sensing and separating 
stations may be arranged in series along the belt conveyor such that each 
of the combinations is responsive to a different color; also, a single 
sensing station may be provided to operate on a number of series-arranged 
separating stations. 
The known installation is rather cumbersome and requires a comparatively 
large number of elements which tends to increase the danger of malfunction 
and/or failures. 
SUMMARY OF THE INVENTION 
Therefore, with the foregoing in mind, it is a primary object of the 
present invention to provide a new and improved construction of apparatus 
for measuring the color of glass, particularly broken glass pieces, and 
which apparatus is not afflicted with the drawbacks and limitations of the 
prior art constructions heretofore discussed. 
Another and more specific object of the present invention is directed to 
the provision of a new and improved construction of apparatus for 
measuring the color of glass, particularly broken glass pieces, and which 
apparatus is of comparatively simple construction and thus less prone to 
malfunction and/or failure. 
It is another important object of the present invention to provide a new 
and improved construction of apparatus for measuring the color of glass, 
particularly broken glass pieces, and which apparatus has a favorable 
price. 
Now in order to implement these and still further objects of the invention, 
which will become more readily apparent as the description proceeds, the 
apparatus of the present development is manifested by the features that, 
among other things, 
(a) groups of photoelectric detectors are arranged at an end face of 
respective substantially cylindrical tubes, 
(b) the tubes define axes which enclose a predetermined angle and which 
intersect in a conveying plane defined by the conveying path, 
(c) optical lens systems are retained in the respective tubes, each optical 
lens system imaging the conveying plane defined by the conveying path at 
an associated group of photoelectric detectors, and 
(d) optical filters precede the respective groups of photoelectric 
detectors and have different spectral transmission regions. 
Thus completely separated paths of rays are provided for the different 
transmission ranges or spectral regions. However, the mirror-image 
relationship in the arrangement of the paths of rays will ensure that the 
detected light originates from the same location of the glass pieces.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Describing now the drawings, it is to be understood that only enough of the 
construction of the apparatus for measuring the color of glass has been 
shown as needed for those skilled in the art to readily understand the 
underlying principles and concepts of the present development while 
simplifying the showing of the drawings. Turning attention now to FIG. 1 
of the drawings, there is schematically shown therein a conveying path 
designated by the reference character 10. In the illustrated exemplary 
embodiment, the conveying path 10 has the form of a slide or chute but may 
have any other suitable structure for conveying the glass, particularly 
broken glass pieces, in a manner such as to permit its investigation by 
the color sensing means described further hereinbelow. As stated, scrap 
glass or broken glass is conveyed along the slide or chute 10 in a 
conveying direction indicated by the arrows 12. 
The conveying path, i.e. the slide or chute 10 has incorporated therein a 
plate 14 for diffusively transmitting light which originates from a 
reflector 16 placed below the plate 14. The reflector 16 is associated 
with an elongate light source 18 extending substantially transverse across 
the conveying path, i.e. the slide or chute 10. The light source 18 
constitutes, for example, a fluorescent lamp which emits substantially 
white light. 
The emitted light passes through the scrap or broken glass pieces which 
pass along the conveying path, i.e. the slide or chute 10 and which are 
substantially uniformly illuminated by means of the diffusively light 
transmitting plate 14. The throughpassed light is detected by means of a 
light sensor or sensing head 20 which is constructed in a manner such as 
to sense the light intensity in two different spectral regions. An 
evaluation circuit 22 is connected to the output side of the sensor or 
sensing head 20 and selectively associates respective pieces of scrap or 
broken glass with either a throughpassing fraction or a fraction to be 
separated in accordance with the transmitted light intensity detected in 
the two spectral regions. Details of the manner in which the transmitted 
light intensity is related to the color of the glass pieces are described 
in the initially cross-referenced U.S. patent application which is 
incorporated herein by reference. 
The evaluation circuit 22 controls an effector system 104 composed of a 
plural number of effectors 24,26 each of which includes a compressed air 
nozzle 24 and a valve 26 governing the air nozzle 24. The valve 26 is 
supplied with compressed air through a connector 28. The compressed air is 
selectively either shut off or passed to the nozzle 24 through the valve 
26, which is controlled by the evaluation circuit 22. A multiple number of 
the just described effectors 24,26 is arranged in a row to form the 
effector system 104 which extends across the width of the conveying path, 
i.e. the slide or chute 10. 
The effector system 104 as described hereinbefore is located at the end of 
the conveying path, i.e. the slide or chute 10. If the evaluated piece of 
scrap or broken glass is classified as "to be separated", the valve 26 is 
opened. An air jet 30 issuing from the compressed air nozzle 24, blows the 
piece of scrap or broken glass away so that such piece passes via a 
further slide or chute 32 into a container 34 for collecting the fraction 
to be separated. Otherwise, the piece of scrap or broken glass passes 
through and drops onto a still further slide or chute 36 and thereby into 
a further container 38 for collecting the throughpassing fraction. The 
evaluation circuit 22 receives classification parameters via a line or 
conductor 40. Data from the evaluation circuit 22 are supplied to a 
central control unit of the installation through a line or conductor 42. 
FIG. 2 shows the light sensor or sensing head 20 which actually forms a 
unit for measuring in two spectral regions the light transmitted by the 
pieces of scrap or broken glass located below the light sensor or unit 20 
on the conveying path, i.e. the slide or chute 10. 
The light sensor or unit 20 includes a main body 44. The main body 44 
defines a planar surface 46 on its bottom side facing a conveying plane 88 
defined by the conveying path, i.e. the slide or chute 10. The main body 
44 has a top side remote from the conveying path, i.e. the slide or chute 
10. This top side is constructed in a roof-like manner by means of two 
members having top faces 48 and 50 which are inclined relative to each 
other and enclose an obtuse angle. The respective bottom faces are 
provided with bores or cutouts 52 and 54 defining respective axes which 
enclose an angle and extend substantially perpendicular to the respective 
top faces 48 and 50. Tubes 60 and 62 are inserted into the respective 
bores or cutouts 52 and 54. The tubes 60 and 62 define respective 
lengthwise axes 56 and 58 which are substantially coincident with the axes 
of the associated bores or cutouts 52 and 54 and likewise form an angle 
with each other and intersect in the conveying plane 88 as defined by the 
conveying path, i.e. the slide or chute 10. 
Extending from the top faces 48 and 50 of the main body 44 are respective 
shallow, substantially rectangular recesses 64 and 66 which are 
substantially centered relative to the axes 56 and 58 of the respective 
tubes 60 and 62. The recesses 64 and 66 are adjoined by respective, 
likewise substantially rectangular recesses 68 and 70 of smaller 
cross-section. The recesses 68 and 70 likewise are substantially centered 
relative to the axes 56 and 58 of the respective tubes 60 and 62. The 
recesses 68 and 70 are respectively connected through substantially 
rectangular apertures 72 and 74 with the bores or cutouts 52 and 54 and 
thus with the interior of the respective tubes 60 and 62. The apertures 72 
and 74 likewise are substantially centered to the axes 56 and 58 of the 
respective tubes 60 and 62. 
Photoelectric detectors 76 and 78 are respectively placed in the recesses 
68 and 70. The arrangement is such that the photoelectric detectors are 
placed on top of the respective tubes 60 and 62 above the tp end faces 
remote from the conveying path, i.e. the slide or chute 10. Optical 
filters 84 and 86 are disposed in the respective substantially rectangular 
recesses 68 and 70 of smaller cross-section. The optical filters 84 and 86 
are different from each other with respect to their optical or spectral 
transmission region as required for classification of the pieces of scrap 
or broken glass according to color, see also the initially 
cross-referenced U.S. patent application which is incorporated herein by 
reference. 
Apertured plates 106,108 are respectively located above the respective 
optical filters 84 and 86 as will be readily recognized in FIG. 3b the 
drawings. Each one of the apertured plates 106,108 contains two rows 
100,102 of round holes which are disposed at an offset from each other. As 
will be further recognized in FIG. 3b, four apertured plates 106 and 108 
are combined to form a structural unit whereby assemblage of the inventive 
apparatus will be considerably facilitated. 
It will be recognized in FIG. 3c of the drawings that circuit boards 110 
and 112 are disposed above the respective apertured plates 106,108 on the 
respective roof-like top faces 48 and 50 of the main body 44. On their 
bottom side, the circuit boards 110 and 112 support respective groups of 
photoelectric detectors 76 and 78, for example, photo-transistors. These 
elements are arranged such as to be aligned with the holes in the 
apertured plates 106 and 108. The components placed on the top side of the 
circuit boards 110 and 112 are not specifically described but serve in 
conventional manner for operating the photoelectric detectors 76 and 78 
located on the bottom side of the circuit boards 110 and 112. 
Centering pins 114 and 116 serve for substantially centering the respective 
circuit boards 110,112 at the main body 44 or the respective roof-like top 
faces 48 and 50. 
Imaging optical lens systems 80 and 82 are respectively placed in the lower 
ends of the tubes 60 and 62 such as to face the conveying plane 88 defined 
by the conveying path, i.e. the slide or chute 10. As will be seen in FIG. 
2 of the drawings, the axes 56 and 58 of the respective tubes 60 and 62 
also define optical axes of the respective optical lens systems 80 and 82. 
The optical axes likewise intersect essentially in the conveying plane 88 
defined by the conveying path, i.e. the slide or chute 10, or slightly 
above thereof at the surface of the pieces of scrap or broken glass passed 
along the conveying path, i.e. the slide or chute 10. This conveying plane 
88 is imaged by the optical lens systems 80 and 82 at the associated 
photoelectric detectors 76 and 78. The border rays of respective imaging 
light beams 94 and 96 are illustrated in FIG. 2. 
As will be apparent from FIG. 3a of the drawings, the light sensor or unit 
20 encompasses a total of four receiver units 20A,20B,20C,20D provided at 
the main body 44 which constitutes a common support body for such receiver 
units. As shown in FIG. 2, each one of the receiver units 20A,20B,20C, 20D 
comprises two substantially cylindrical tubes 60 and 62 inclusive of the 
associated imaging optical lens system 80,82, the optical filters 84 and 
86 and the photoelectric detectors 76 and 78. The two substantially 
cylindrical tubes 60 and 62 of the receiver units 20A,20B,20C, 20D are 
seen to be arranged above the conveying path, i.e. the slide or chute 10 
in juxtaposition in the conveying direction 12. It will also be apparent 
from these drawings that the light sensor or unit 20 is composed of two 
rows of such tubes 60 and 62 or receiver units 20A,20B,20C,20D in a manner 
such that the two rows extend essentially transverse to the conveying 
direction 12 or across the width of the conveying path, i.e. the slide or 
chute 10. Since the photoelectric detectors 76 and 78 are aligned with the 
apertured holes in the apertured plates 106,108 which are placed above the 
top end face of the substantially cylindrical tubes 60 and 62, groups of 
photoelectric detectors 76 and 78 are respectively associated with the two 
rows of substantially cylindrical tubes 60 and 62. Each group of 
photoelectric detectors 76 and 78 likewise encompasses two rows arranged 
at an offset in a staggered relationship corresponding to the arrangement 
of holes in the apertured plates 106,108. 
FIG. 4 of the drawings shows 192 substantially circular areas 98 located in 
the conveying plane 88 defined by the conveying path, i.e. the slide or 
chute 10 and the substantially circular areas 98 are under observation by 
the groups of photoelectric detectors 76 and 78. In order to completely 
cover the entire width of the conveying path, i.e. the slide or chute 10, 
two substantially parallel rows 100 and 102 of the substantially circular 
areas 98 are provided and offset from each other. The rows 100 and 102 are 
mutually offset from each other such that the areas 98 assume a staggered 
relationship with respect to each other in a manner generally comparable 
to the staggered arrangement of holes in the apertured plates 106,108 and 
the groups of photoelectric detectors 76,78. 
FIG. 4 of the drawings also shows the position and alignment of the 
effector system 104 relative to the conveying plane 88 defined by the 
conveying path, i.e. the slide or chute 10. Four of the substantially 
circular areas 98 under observation activate a respective one of 48 
effectors 1 to 48 which conjointly form the effector system 104. Thus the 
effector 1 is associated with the substantially circular areas 98 marked 
"1", "2", "3" and "4" and thus is controlled by the photoelectric 
detectors 76,78 located in the receiver unit 20A or 20D, as the case may 
be. 
The evaluation circuit 22 stores a control command controlling the effector 
system 104 and permits activating selected ones or all of the effectors 1 
to 48 at a delay which is determined by the conveying speed of the pieces 
of scrap or broken glass on the conveying path, i.e. the slide or chute 
10, and the spacing between the receiver units 20A,20B,20C,20D and the 
effectors 1 to 48. 
While there are shown and described present preferred embodiments of the 
invention, it is to be distinctly understood that the invention is not 
limited thereto, but may be otherwise variously embodied and practiced 
within the scope of the following claims. Accordingly,