SCANNING SYSTEM FOR BAR CODE LABELS AFFIXED TO RODS

Abstract: A system for identifying a bar code label affixed to a rod wherein the bar code label including each bar thereof gener­ ally circumferentially spans on the rod an angle (the bar code angle) greater than 180° and less than 360° about the rod's longitudinal axis. The system includes a bar code reading optical scanner and a rod positioning mechanism. The scan­ ner has a light beam from a single source and creates two scanning lines which superimposingly intersect at an angle which is greater than 360° minus the bar code angle and which is less than or equal to 180°. The rod positioning mechanism co-linearly (or close enough to such) aligns the rod's longitud­ inal axis with the intersection line of the scanning lines so that the bar code label may be identified independent of the rota­ tional position of the rod about its longitudinal axis.

Description: The present invention relates generally to a system for reading bar code labels and more particularly to a system for identifying bar code labels affixed to nuclear fuel rods. Bar code labels are temporarily affixed to nuclear reactor fuel rod cladding tubes. This enables the fuel rods to be easily tracked during various manufacturing and quality control inspection steps. The bar code labels have been read by manually passing a hand-held optical bar code reader across the bar code portion of the bar code label, longitudinally along the tube. The bar code labels are wrapped only partially around the cladding tube leaving a space on the tube which facilitates later removal of the bar code label. Also, the bar code label may contain an alphanumeric coded portion permitting visual identification of the tube, as well as the bar code portion permitting optical scanner identification. Thus, operators had to manually rotate some of the rods about their longitudinal axes to reveal the bar code portion before manually passing the hand-held reader across the bar code label. What is needed is an identification system which will automatically position a nuclear fuel rod and read its bar code label regardless of the longitudinal rotational position of its bar code portion. Optical scanner systems for reading bar codes on articles are known in various configurations generally attempting to be able to read a bar code label on an article irrespective of the actual orientation of the bar code, however, with the bar code facing toward the optical scanner. Examples of such prior art optical scanners are disclosed in DE-A-27 57 235 and in IBM Technical Disclosure Bulletin, Vol. 22, Nr. 6, November 1979, page 2399. The first mentioned document , DE-A-27 57 235, discloses a system wherein the light beam coming from a light source is first divided by a beam splitter into two diverging beams which are reflected via mirrors on substantially diametrical sides of a rotating reflecting wheel having a plurality of mirrors on its circumference. The reflection wheel mirrors are tilted under small angles with respect to each other so as to produce a number of slightly diverging reflected beams which then are reflected again by further mirrors so as to produce a multiple pattern of intersecting scanning line groups substantially in a scanning plane, enabling reading of a bar code which may have a random orientation. The second-mentioned document discloses a scanner system in which a single rotating mirror cooperates with a number of stationary mirrors so as to produce an inclined but substantially rotating scanning beam. All those prior art devices intend to properly scan a bar code label independent from its actual orientation as long as the bar code is at least substantially facing toward the scanning system. The problem underlying the invention, as indicated above, is a different one. It is not the problem of identifying a bar code which may have various orientations with regard to the scanning system, but it is the problem of identifying a bar code in which the individual bars are wrapped around the circumference of a rod which is relatively small in diameter such as a nuclear fuel rod, with the bar code spanning an angle around the rod axis of at least 180° but less than 360°. The problem underlying the invention is how to properly identify the bar code on the rod irrespective of the actual rotational position of the rod, i.e. the invention seeks to provide a simplified optical scanner system which is able to properly identify the bar code even if it does not really face toward the scanner system, i.e. when a conventional bar code reading system would not be able to scan the bar code. With this object in view, the invention resides in an optical scanner system as defined in any of independent claims 1 and 2. Claims 1 and 2 indicate two alternative solutions of the problem which reliably allow reading of the bar code provided that it spans an angle of at least 180° around the rod axis, independent from the actual rotational position of the bar code with regard to the scanner, i.e. even if the bar code should practically face away from the scanner system. While the above-mentioned DE-A-27 57 235 discloses a sophisticated arrangement using a plurality of optical elements, the present invention provides for a very simple and compact device with only a minor number of optical elements. In the embodiment of claim 1, it is the rotating wheel which produces two diverging beam paths by the alternately tilted arrangement of the mirrors which are inclined to the one or other side of the wheel. In the embodiment of claim 2, the wheel has radially facing mirrors only and a beam splitter in the path of the beam reflected from the wheel produces the two diverging beam paths. The invention, however, both as to organization and method of operation, together with further advantages thereof, may best be understood by reference to the following exemplary description taken in connection with the accompanying drawings in which: Figure 1 is a side schematic instantaneous view of the bar code identification system without the rod positioning mechanism. Figure 2 is a front schematic view of the system of Fig. 1. Figure 3 is a perspective schematic time-averaged view from underneath showing the system of Fig. 1 also including having the rod placed on a weighing scale while its bar code label is read by the scanner. Figure 4 is a front schematic view of the system of Fig. 3 with portions of the bottom of the scanner cut away. Figures 5A, 5B and 5C are perspective schematic views of the rod positioning mechanism in various stages of operation showing how rods are placed in the same position for bar code reading and rod weighing. Reference will now be made in detail to several present preferred embodiments of the invention, an example of which is illustrated in the accompanying drawings. In the drawings, like reference characters designate like or corresponding parts. The Figures show a system for identifying a bar code label 12 affixed to an elongated rod 10. preferably, the rod 10 is cylindrical, such as a nuclear reactor fuel - rod or a cladding tube which has not yet been made into a fuel rod. The bar code portion 14 of the bar code label 12 may contain information such as the individual identification number of the particular rod 10. The bar code label 12 is oriented on the rod 10 such that the bar code portion 14 of the bar code label 12 generally spans an angle (called the bar code angle), about the rod's longitudinal axis, which is greater than 180° and less than 360°, with each of the bars of the bar code portion 14 generally circumferentially wrapping around the rod 10 to generally lie in a separate plane which is generally perpendicular to the rod's longitudinal axis. The system of the invention includes a bar code reading optical scanner 16 (best seen in Figs. 1 and 2) and means for disposing the rod 10 (seen in Figs. 5A, 5B, and 5C) which combine to cause two scanning lines 40a and 40b from the scanner 16 to intercept the surface of the rod 10 from opposite sides, so that at least one scanning line will intercept the bar code portion 14 of the bar code label 12 (best seen in Figs. 3 and 4). The scanner 16 will therefore be able to identify the bar code label 12 independent of the rotational position of the rod 10 about its longitudinal axis. The scanner 16 is enclosed in a housing 17 and employs a light beam 34 from a single source, such as a laser 18. Means are provided for deflecting the light beam 34 to produce two diverging scanning lines 38a and 38b. Preferably, such means includes a beam splitter 20 and a modified spindex 22. The beam splitter 20 serves to direct the light beam 34 to the spindex 22 along light beam 36 and to direct the mediately returning light beam from the spindex 22 (after reflection from the bar code label 12) to the optical detector 30 along light beam 42. It is known to use a beam splitter and a standard spindex to produce one scanning line from a laser's light beam. A standard or modified spindex is a wheel turned by a motor 23. The wheel has a plurality of mirrors on its circumference. In a standard spindex, the faces of the mirrors point radially outward from the wheel's center so that a perpendicular to the mirror passing through the mirror's center will be generally coplanar with and perpendicular to the axis of rotation of the spindex. As the wheel turns, a single mirror will produce a single scanning line. Each other mirror, in turn, will repeat the original scanning line. In a modified spindex 22, the faces of the mirrors 24 are alternately tilted at a fixed angle to one or the other side of the wheel so that when the light beam 36 from the beam splitter 20 strikes a first mirror 24a rotating on the modified spindex 22, a first diverging scanning line 38a will be produced which will be diverging from the second diverging scanning line 38b produced by the light beam 36 later striking the second mirror 24b as it rotates on the modified spindex 22 to face the light beam 36. This is an example of deflecting the light beam 34 to produce two diverging and alternating scanning lines 38a and 38b. Other beam deflecting means includes dividing the repeating single scanning line from a standard spindex by a second beam splitter into two non-alternating diverging scanning lines. Alternating diverging scanning lines are preferred to non-alternating ones because of the visual noise problem. By visual noise is meant the condition which occurs when one beam is reading the bar code and the other beam is seeing something else, such as alphanumeric data. The scanner can read a good return alternated in time with a bad return more easily than when the good and bad returns arrive at the same time for decoding. Other beam deflecting means includes intercepting the repeating single scanning line of a standard spindex with a mirror which flip flops between two orientation positions producing alternating diverging - scanning lines. Means are also provided for reflecting the two diverging scanning lines 38a and 38b to converge and to generally colinearly and superimposing intersect, defining a general line of intersection, with the two converging scanning lines 40a and 40b intersecting at an angle greater than 360° minus the bar code angle, and up to 180°. Fig. 1 shows diverging scanning line 38a and converging scanning line 40a at an instant in time (so that the interception line on the surface of the rod 10 would be a traveling point frozen in time as a dot on the bar code portion 14 of the bar code label 12.) Fig. 3 is a time-averaged view, showing an interception line 60a, and also showing converging scanning lines 40a band 40b having, respectively, a top 56a and 56b and a bottom 58a and 58b. It is noted that the two converging scanning lines 40a and 40b intersect each other and define a line of intersection only when a rod 10 is not present. When a rod 10 is present, the two converging scanning lines 40a and 40b intercept the rod's surface defining the two interception lines (such as the one 60a shown in Fig. 3). Preferably, the reflecting means includes a single mirror 26a to reflect diverging scanning line 38a as converging scanning line 40a and a single mirror 26b to reflect diverging scanning line 38b as converging scanning line 40b. Windows 28a and 28b in the scanner housing 17 transmit the converging scanning lines 40a and 40b outside towards the rod 10. Other reflecting means includes two or more mirrors to be used to redirect each diverging scanning line by steps or stages until the desired converging conditions are achieved. The general line of intersection of the converging scanning lines 40a and 40b with each other may include the intersection of two generally flat arcs without interfering with the reading of the bar codes. The scanner 16 includes an electronics package 32, known to those skilled in the art, to activate the spindex motor 23 and the laser 18, and to decode the output from the detector 30 to read the bar code being interrogated by either or both scanning lines 40a and 40b striking the rod 10. The electronics package 32 is attached to the motor 23 by a wire 46, to the laser 18 by a cable 44, and to the detector 30 by a lead 48. The dimensions of the modified spindex 22 including the spindex mirrors 24 are chosen, as can be computed by those skilled in the art, so that together with the mirrors 26, the line of intersection of the converging scanning lines 40a and 40b with each other is greater in length than the width of the bar code portion 14 of the bar code label 12. The means for disposing the rod 10 are means for disposing the rod to align the rod's longitudinal axis generally coplanar with and generally parallel to the intersection line, to axially position the bar code portion of the bar bode label within the axial position of the intersection line and to transversely position the rod's longitudinal axis sufficiently close to the intersection line for the converging scanning lines to intercept the surface of the rod along intercepting scanning lines (such as intercepting scanning line 60a shown in Fig. 3), with the intercepting scanning lines subtending an angle about the longitudinal axis of greater than 360° minus the bar code angle and up to 180°. preferably, such rod disposing means simply disposes the rod 10 with its longitudinal axis generally colinear with the intersection line. It is also preferred that the bar code angle be about 270° and the two converging scanning lines 40a and 40b intersect each other at an angle of about 120°. The rod disposing means could be any conventional rod handling equipment, including the use of robots, but preferably, such means includes a loading ramp 68, escapement or loading wheel 70, loading arm 74, rod holder 64, unloading arm 78, and an unloading ramp 82 (as seen in Figs. 5A, 5B and 5C). The rod holders 64 are fixedly positioned underneath the scanner 16 such that the line of intersection of the converging scanning lines 40a and 40b would be colinear with the longitudinal axis of a rod 10 if placed in the rod holders 64. The rods 10 may be axially positioned manually on the ramp 68 to later be transferred to the rod holders 64 such that the bar code portions 14 are within the axial position of the scanner's intersection line. This result could be accomplished automatically by mechanically pushing one end of the rods against a stop located to the side of the ramp 68, as is known to those skilled in the art. In operation, the axially positioned rods 10 roll down the loading ramp 68. The leading rod 10a fits in a recess 71 of the loading wheels 70. A shaft 72 turns the loading wheels 70 transporting the rod to the loading arms 74. A shaft 76 turns the loading arm 74 lowering the rod 10a to the rod holder 64. The scanner 16 then interrogates the bar code label 12 along the two intercepting scanning lines. After the bar code label 12 is read, a shaft 80 turns the unloading arms 78 raising the rod 10a to the unloading ramp 82. Preferably, the rod disposing means also includes means for weighing the rod 10a when it is in position for reading of its bar code label 12. Preferably, such weighing means includes a scale 62 upon which the rod holders 64 are attached. It is desirable to also have computer means, such as a computer 52, for electronically storing the rod weight from the scale 62 and the rod identification from the scanner 16. The scanner 16 and the scale 62 would be connected to the computer by data links 50 and 66, respectively. The computer means could also be utilized as a single controller to synchronize the operation of the rod disposing means and the scanner 16 to achieve fully automatic rod weighing and bar code label identification, as can be appreciated by those skilled in the art. It will be apparent that many modifications and variations are possible in light of the above teachings. It, therefore, is to be understood that within the scope of the appended claims, the invention may be practiced other than as specifically described.

Claims: An optical scanner for identifying a bar code (12) on an elongated rod (l0) with each of the bars (14) of said bar code generally circumferentially wrapping around said rod spanning an angle greater than 180° and less than 360° about the rod axis, the scanner comprising a light source (18) for producing a light beam (34) , a system of mirrors (22, 26) including a motor driven rotating wheel (22) having a plurality of mirrors (24) arranged on its circumference for reflecting said light beam (34) so as to produce a moving scanning beam (38, 40) sweeping across said bar code (12) , and an optical detector (30) responding to light reflected from the bar code, characterized in that said mirrors (24) on said rotating wheel (22) are alternately tilted (24a, 24b) at a fixed angle to the one or the other side of the wheel so as to alternately produce two diverging scanning beam paths, each of said diverging scanning beam paths (38a, 38b) has associated therewith a mirror (26a, 26b) for reflecting the beam such that the two scanning beam paths (40a, 40b) then converge and intersect, and that said optical scanner (16) has associated therewith a disposing device (46) for disposing said rod (10) to align the rod axis to the sweeping path of both scanning beams. An optical scanner for identifying a bar code (12) on an elongated rod (10) with each of the bars (14) of said bar code generally circumferentially wrapping around said rod spanning an angle greater than 180° and less than 360° about the rod axis, the scanner comprising a light source (18) for producing a light beam (34), a system of mirrors (22, 26) including a motor driven rotating wheel (22) having a plurality of mirrors (24) arranged on its circumference for reflecting said light beam (34) so as to produce a moving scanning beam (38, 40) sweeping across said bar code (12), and an optical detector (30) responding to light reflected from the bar code, characterized in that said mirrors (24) on said rotating wheel (22) are radially facing mirrors, a beam splitter (not shown) is provided to divide the light beam after reflecting rotating reflector wheel so as to produce two diverging scanning beams, each of said diverging scanning beams (38a, 38b) has associated therewith a mirror (26a, 26b) for reflecting it such that the two scanning beams (40a, 40b) then converge and intersect and that said optical scanner (16) has associated therewith a disposing device (46) for disposing said rod (10) to align the rod axis to the sweeping path of both scanning beams.

Inventors: AHMED, HASSAN JUMA, FOGG, JAMES LOREN
Applicants: WESTINGHOUSE ELECTRIC CORPORATION
Application year: 1984
Main classification: G06K7
IPC codes: G06K7, B07C5