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BACKGROUND OF THE INVENTION
This invention relates to label readers and labels therefore, and more
particularly to binary coded concentric-ringed labels and scanning label
readers for concentric-ringed labels.
With the increasing popularity of large discount department stores having a
single point of sale for many various departments and increasingly large
inventory monitoring requirements for manufacturing outlets, retail
supermarkets, warehouses, etc., the need for apparatus capable of
recording each and every item that is sold has become evident. The field
of use is not limited, however, and the development of equipment which
allows individual placement on a multitude of objects of a specific code
which represents price, inventory number, destination, address, routing,
flight number, security information, etc., and then reading the particular
code, permits the automation of sales data accumulation, the driving of
electronic cash registers, the automation of inventory control, and the
automatic routing and sorting of packages, boxes, mail, baggage, and all
other materials to which a code is secured. Many devices have been
developed and tested in an attempt to make inroads into this
ever-expanding field, but these systems have various inherent drawbacks
preventing their widespread use.
The major disadvantage with most of the label-reading machines known in the
prior art is the requirement for orientation or positioning of the label
relative to the reader or vice-versa. This orientation requirement makes
the use of the label cumbersome while increasing the handling time. As a
result, these systems are generally used only in special circumstances.
Another common problem is the requirement for relatively expensive labels
which are affixed to each item. Most of these labels require either
retro-reflective strips or ink, fluorescent ink, or various colors to
properly code the label. Furthermore, virtually all of the labels used in
the prior art require expensive readers and are not capable of being
prepared by truly cheap and portable label imprinters.
In the few systems which are capable of employing inexpensive labels, the
cost of using the system becomes prohibitively expensive since sales
personnel are required to initiate and/or operate the label-reading device
manually in order to provide the desired information. As a result, the
prior art label readers and the labels therefor have not been employed in
the areas where there is a great need for such equipment, such as
inventory control, sales accounting, material handling or shipping systems
involving a large number of relatively inexpensive items, such as retail
food supermarkets, manufacturing, military warehouses, drug distribution
centers, parcel post, etc.
OBJECTS OF THE INVENTION
Therefore, it is a primary object of this invention to provide a label
reader and a label therefor which does not require orientation or
positioning of one relative to the other, the label being readable upon
traversing exposure to the label reader in any label orientation.
Another object of this invention is to provide the label reader and label
therefor as defined above which operates efficiently with expensive labels
and a simple label reader, or with less expensive labels and a more
complex label reader.
Another object of this invention is to provide the label reader and labels
therefor as defined above that operate completely automatically.
Another object of this invention is to provide a label as defined above
which substantially eliminates false or erroneous readings.
Other and more specific objects will be apparent from the features,
elements, combinations and operations procedures disclosed in the
following detailed description and shown in the drawings.
SUMMARY OF THE INVENTION
The label and label reader of this invention obviate the disadvantages
found in prior art systems while being inexpensive to employ and maintain.
The cost of labels are held to a small fraction of a cent by using coded
concentric rings printed on the label without expensive inks or colors. An
inexpensive label reader is provided by the development of a reader that
eliminates fragile and expensive lenses or other optical and mechanical
components and instead merely employs relatively inexpensive optical and
digital components. The substantial cost benefit which can be realized in
such areas as inventory control by the use of the system of this invention
will also benefit consumers by providing the capability for retail price
reductions.
In the preferred embodiment, the label incorporates concentric white and
black rings of uniform width that can be arranged in binary code to
display any desired information. The concentric ringed label provides a
unique advantage over most prior art labels since it has no preferred
reading orientation. This eliminates reader handling by the operator and
substantially reduces the time involved in reading the label. A complete
scan substantially through the center of the label will read the label
code regardless of the point on the outer circumference of the label where
the scan commenced.
The binary code information displayed on the label is read by a
continuously scanning light beam which scans the label as the label passes
over a narrow scanning slit, formed as part of the reader housing. The
label reader is adapted to read the scanned label information continuously
across nondiametric chords of the label, as the label's chords are exposed
to the scanning slit, to decode and translate the data into digital
signals, to record the digital signals, and discard these recorded sognals
until the label reader has scanned across a diameter of the label. This
complete scan information is then transferred to data storage or a
computer interface, or is decoded to provide control signals.
A complete coded signal is only read from the label when the label reader
has scanned substantially across the diameter of the label. All prior and
subsequent scans provide only partial information and do not necessarily
provide the entire information desired. Consequently, the label reader is
adapted, using relatively inexpensive electrical equipment to,
continuously receive partial information scans, discard the scans, receive
the desired scan with the complete coded information, recognize this scan
as the desired one, and send the information to data storage. As used
herein, the term label is intended to mean any configuration of data in
accordance with the present invention, and not merely a physically
attachable label.
In the preferred embodiment, the label reader incorporates a coherent light
beam source, preferably a laser beam, and projects the beam of light onto
a rotating mirror drum having a plurality of reflecting surfaces. The
rotating mirror is positioned below the scanning slit over which the label
is passed to provide scanning movement of the light beam across the label
surface. As the mirror drum rotates, the light beam scans across the slit
until the beam now reflects off another drum surface starting a new beam
at the beginning of the slit. The light beam passes through a restricted
aperture to assure that the light beam will scan only from one end of the
narrow slit to the other.
As the label and the goods to which the label is attached pass over the
narrow slit, the scanning light beam causes a flash of label-reflected
light to be generated when the beam hits the white circles while
substantially no light flash is generated as the beam passes across the
black circles. These flashes of light are conducted by a light pipe to
impinge upon a sensor positioned within the label reader.
In order to assure that the flash of light is properly recorded by the
sensor, the surrounding light pipe walls which are located between the
scanning slit and the sensor, preferably, all incorporate mirrors. These
peripherally surrounding highly reflective surfaces capture and direct the
reflected light to provide a uniform signal at the base of the light pipe,
assuring proper stimulation of the sensor.
The label flash sensor is part of a label information assembly which
comprises relatively inexpensive digital components which are adapted to
convert the sensor output into a digital signal, determine whether or not
the signal represents the complete label information which would represent
a scan substantially along the diameter of the label, and transmit the
complete information signal to data storage.
The labels required for properly displaying the desired coded information
for efficient reading by the label reader do not require retro-reflective
strips or ink, fluorescent inks, or colors. Inexpensive grade paper,
easily printed with black and white concentric rings, performs effectively
in the system of this invention. If desired, a single retro-reflective
center dot can be employed to reduce the digital components necessary to
recognize the center scan of the label.
The digital components which are used for the label information assembly
comprise five basic units. First, the information assembly incorporates a
system reset unit which places the associated equipment into an
information receipt mode after an object bearing a label has cleared the
scanning slit or after a label reading has been completed. Next, as the
label is being scanned, a label reflectivity decoder receives the flashes
from the label and in cooperation with a shift pulse generator converts
the first and second symmetrical portions of label signal output into a
digital signal, which is stored in two shift register units for
comparison.
A label information transfer unit determines when a scan has been made
substantially across the diameter of the label by comparing the signals
stored in the two shift registers for equality, and analyzing each scan or
successive pairs of scans for satisfaction of certain conditions which are
present only with a label diameter scan. When a label diameter scan is
confirmed, a data ready signal is initiated to shift the signal from the
registers to a data transfer interface.
The invention accordingly comprises the features, elements, combinations
and operating procedures hereinafter disclosed, and the scope of the
invention will be indicated in the claims.
THE DRAWINGS
For a fuller understanding of the nature and objects of the invention,
reference should be had to the following detailed description taken in
connection with the accompanying drawings, in which:
FIG. 1 is a plan view of one embodiment of the label of this invention;
FIG. 2 is a plan view of another embodiment of the label of this invention;
FIG. 3 is a perspectiive view partially broken away of the label reader of
this invention;
FIG. 4 is a block diagram of the label information assembly according to
this invention;
FIG. 5 is a detailed electrical circuit diagram of one embodiment of the
label information assembly of FIG. 4;
FIG. 6 is a timing diagram for the label information assembly of FIG. 5,
when scanning along a diameter of the label of FIG. 1;
FIG. 7, comprising FIGS. 7A and 7B, is a detailed electrical circuit
diagram of a second embodiment of the label information assembly of FIG.
4;
FIG. 8 is a timing diagram for the label information assembly of FIG. 7,
when scanning along a diameter of the label of FIG. 2;
FIG. 9 is a diagramatic view of label sections with timing diagrams for
selected label scans;
FIG. 10 is an enlarged side view of the mirror drum of the label reader of
FIG. 3;
FIG. 11 is a top view of the mirror drum of FIG. 10; and
FIG. 12 is a greatly enlarged cross-sectional side elevation view of the
mirror drum taken along line 12--12 of FIG. 11.
LABEL WITH HIGHLY REFLECTIVE INNER DOT
In FIG. 1, one embodiment of the label of this invention is presented. In
this embodiment, label 20 comprises sixteen equal width concentric rings
21 which are either black or white in color and a seventeenth center
circle ring 23 which is white in color. Within center circle 23 is located
a more highly-reflective inner dot 22.
The desired information is coded on label 20 in binary form with the black
rings representing the binary number 0 and the white rings representing
the binary number 1. Although the pure binary code is often preferred for
information-packing, the functioning of the system is not dependent on the
coding used on the label. Therefore, any coding scheme such as the
American Standard Code for Information Interchange (ASCII), or any of the
many decimal codes, error detecting codes, and error correcting codes
commonly used may be employed.
Since rings 21 are concentric, the label is capable of being read by
transverse scanning or irradiation from any direction, with the coded
information being properly displayed whenever the label is read along any
diameter. Although the scanning or irradiation apparatus can take several
different forms, substantially all such means must incorporate a source of
radiation, which impinges on the concentric rings of the coded label, and
a reflectivity level sensor for detecting the reflectivity level of the
concentric rings and transmitting a representative signal therefor. The
irradiation reading of the concentric rings of the coded label can be
performed mechanically, electrically, or optically. Mechanical irradiation
is achieved by the relative movement of the radiation beam and the label,
by moving the beam across a stationary label, by moving the label across a
stationary beam, or by independently moving both the label and the beam.
Electrical irradiation reading is obtained by a network of sensors adapted
to detect the reflectivity levels of the concentric rings of a moving or
stationary coded label, and to transmit the desired signal. Optical
irradiation reading is also applicable to both moving and stationary
labels and is achieved by delivering the radiation reflections of the
individual concentric rings to one or more sensor/transmitters. It should
be apparent to one skilled in the art that many combinations of
mechanical, electrical and optical irradiation reading means are possible
without departing from the scope of this invention.
The label is completely free of orientation or positioning requirements.
Using seventeen concentric equal width rings and the binary coding system,
there are 2.sup.17 possible combinations or 131,072 different coding
combinations for the black or white rings. The 17 bit binary number, which
can represent the decimal number 1 through 131,072, can be readily
translated to a decimal number either in a computer or with digital
decoding logic.
The label, however, is not limited to 17 equally spaced rings and any
desired number of rings can be employed. Theoretically, the radial width
of each concentric ring need only be as large as the diameter of the beam
at its maximum defocused point along the scanning plane. Unfortunately,
practical considerations impose substantial limitations on the theory. One
of the ultimate factors to be considered is the environmental conditions
under which the label is read. If high vibrations are present, the radial
width of each label must be wide enough to prevent any vibration induced
scanning beam oscillation from scanning beyond the boundaries of the
particular ring being scanned. Otherwise, erroneous code reading will
result.
Along with the desired size label required for the particular application,
the speed with which the label will be passed over the reader and/or the
number of non-coded center rings allowable must also be considered in
determining the radial width of the rings, when the system is operating at
a given scanning speed. For most applications, and under most conditions,
14-40 concentric rings are considered to meet fully the coding
requirements while also being capable of error-free reading.
By increasing the number of equally spaced concentric rings, the number of
different possible combinations increases exponentially. For example, with
20 equally spaced rings, there would be 2.sup.20 or 1,048,576 different
combinations, while with 24 equally spaced rings there would be 2.sup.24
or 16,777,216 combinations or sufficient representations for the decimal
numbers 1 through 16,777,216. The number of concentric rings employed, the
radial width of each concentric ring, and the diameter of the label are
all variable sizes which can be selected for the particular application
for which the label will be used.
While concentric rings which are either black or white in color are
preferred, any color rings having contrasting radiation reflectivity
levels can be used. Furthermore, concentric rings having a plurality of
different reflectivity levels can also be employed. For simplicity,
however, two contrasting colors and the binary coding system are
preferred.
Inner dot 22, which is located within center circle 23, of label 20
comprises a material having a reflectivity level that is several times
greater than the white portion of the label or the highest reflectivity
level of the concentric rings. Preferably, inner dot 22 comprises a
non-glossy material in order to insure that the reflected light is
uniformly scattered. Furthermore, in this embodiment of the invention,
center circle 23, having a radius equal to the radial width of rings 21,
is not used for information storage. Instead, center circle 23 is
preferably coded white in order to prevent the anomaly of having a high
reflectivity level sensed during a black or non-reflective ring scan.
Although not required, retro-reflective materials can be employed for inner
dot 22. Retro-reflective materials which have been successfully used are
Scotch-Lite brand reflective sheeting, described in 3M Company product
bulletin 85-4; and the Reflective Liquids described in 3M Company
Information Folder No. 100 and Information Folder No. 100A.
Label 20 may be printed on inexpensive white nonglossy paper, with the
black concentric circles printed thereon with non-glossy ink. Inner dot 22
can be adhesively joined to the label or the label can be provided with a
center hole and adhesively joined to the reflective material. If
reflective liquids are employed, inner dot 22 can be silk-screened,
printed, or painted onto the paper stock. Also, reflective sheet stock can
be used with label 20 formed by printing the coded concentric rings
directly on the reflective paper with no printing where the inner dot is
to be. If desired, label 20 may have an adhesive backing for easy
application to any particular object.
LABEL WITHOUT HIGHLY-REFLECTIVE INNER DOT
Another embodiment of the label of this invention is shown in FIG. 2. Label
25 of FIG. 2 is very similar to label 20 of FIG. 1 in that both comprise a
plurality of equal width concentric rings 21 which preferably incorporate
two contrasting radiation reflectivity levels. Label 25 differs from label
20 in that label 25 does not incorporate an inner dot formed of
retro-reflective or other high reflectivity material having a radiation
reflectivity level that is several times greater than the highest
reflectivity level of the concentric rings.
Label 25 merely comprises a plurality of equal width concentric rings 21
having different levels of reflectivity. As with label 20, the information
coded on label 25 can be read along any of its diameters, thereby
eliminating any requirement of orientation or positioning of the label.
The major advantage of label 25 is its substantially lower cost since no
center circle of high reflectivity is used.
In the preferred embodiments, each label 20 or 25 is individually coded
using the binary system with each black ring representing the binary
number 0 while each white ring represents the binary number 1. As
discussed above, any number of concentric rings can be employed in order
to provide a label which meets the requirements of the particular
situation for which the label will be used.
Both labels 20 and 25 preferably appear on a plain background to reduce to
zero the possibility of a false reading due to printing or designs on the
background. Although the probability of this happening is very low, it is
not zero. It is conceivable that the labels could be placed on a package
with decorative bulls eye patterns with precisely the exact geometrical
design to be interpreted as a coded label. The possibility of false
readings due to the background involves no particular restriction in a
situation where the labels are applied at the origin of manufacture as the
background decoration can be easily analyzed and tested for the
possibility of generating false readings. Furthermore, in situations where
it is necessary to permit unrestricted use of the labels on any
background, the probability of incorrect readings due to the background
printing or decoration can be reduced to almost zero by the use of error
detection and/or error correction codes on the label (at the expense of a
slight reduction in the information capacity of the label).
Also, the labels of this invention essentially eliminate false or erroneous
readings. Since only diameter scans are used and the probability of having
dirt spots or other error producing marks symmetrically disposed about the
label's center along the scanning path is extremely low, improper readings
are almost impossible. It is more likely that soiled labels will produce
no reading instead of a false reading. This is generally preferred since
false readings are more difficult to trace and rectify than having no
reading at all. Furthermore, as will be discussed below, any item bearing
a label which is not read can be identified with the aid of a label scan
reset unit. As a result the labels of this invention are powerful
geometrically as well as statistically.
LABEL READER
In FIG. 3, the preferred embodiment of the label reader of this invention
is shown. Label reader 27 comprises main housing 28 and two demountable
housings 29 and 30. Extending between housings 29 and 30 is a narrow
scanning slit 31, across which containers or objects bearing downward
facing labels 20 or 25 are moved for label reading.
Housing 28 surroundingly encloses the beam scanning equipment 34, a light
pipe 35, and the associated electronics. Beam scanning equipment 34
incorporates a coherent radiation beam source such as a small laser 36, a
focusing lens 37, folding mirrors 38, and a beam scanner 39. In the
preferred embodiment, beam scanner 39 comprises an octagonal shaped mirror
drum 40, which is axially connected to synchronous driving motor 41.
As the coherent radiation beam impinges upon one of the mirror surfaces of
mirror drum 40, the beam is reflected upwardly through an aperture 42 to a
scanning slit 31. As motor 41 rotates mirror 40, the reflected beam scans
across slit 31 from one end to the other end thereof. Aperture 42 is
preset to provide a scanning beam which exactly coincides with the length
of scanning slit 31. Once the reflected beam has scanned across the entire
length of slit 31, the reflecting surface of mirror 40 will have rotated
to a position where the radiation beam no longer impinges upon the surface
and instead impinges upon the next mirror surface, causing a new beam to
be reflected through aperture 42 to the front end of scanning slit 31. As
a result, successive scanning beams continuously sweep across the entire
length of slit 31, providing a scanning radiation source for impingement
upon the concentric ringed label.
As best seen in FIG. 10, octagonal shaped mirror drum 40 comprises an
octagonal shaped support 74 having eight substantially flat
circumferentially disposed surfaces 75 with mirrors 76 in juxtaposed
spaced relationship to surfaces 75 and secured to support 74. As can best
be seen in FIGS. 11 and 12, mirrors 76 are secured to surfaces 75 by means
of screws 77 and washers 78.
Referring to FIG. 12, mirror 76 comprises a glass base 80 with a reflecting
material 81, such as silver oxide, deposited on the surface thereof.
Interposed between mirror 76 and surface 75 of support 74 is a resiliently
depressable adhesive 82. Adhesive 82 aids in holding mirror 76 to support
74 while also providing a resiliently depressable cushion for adjustment
of the mirror pitch angle relative to support 74.
As support 74 continuously rotates about its central axis, the laser beam
impinges upon one of the mirrors 76 and is reflected through aperture 42
and projected up to the scanning slit, (not shown). As support 74 rotates,
mirror 76 similarly rotates causing the projected beam to sweep across
aperture 42 and the scanning slit. When one of the mirrors 76 has rotated
to a position where the laser beam no longer reflects off that surface,
the following mirror will be in position to repeat the beam projection and
sweeping operation.
In order to provide the desired scanning of the label, the projected laser
beam must continuously sweep across the scanning slit through
substantially the same plane. In order to assure sweeping movement of the
beam in substantially the same plane, the angular relationship of mirrors
76 to support 74 are adjusted by means of screws 77 and washers 78. The
ease of adjustment is enhanced by incorporating resiliently depressable
adhesive 82 between the mirror 76 and surface 75 of support 74.
Consequently, adjustment screws 77 and washers 78 quickly and easily allow
the necessary angular adjustment required for mirrors 76 to be made,
thereby assuring the required planer similarity of the beams scanning
path.
As the scanning beam sweeps across scanning slit 31, the beam impinges upon
the concentric rings of the label from one edge to the other edge thereof,
as the label passes over slit 31. When the radiation beam impinges upon
the black concentric rings, virtually no radiation reflection results.
However, when the scanning beam sweeps across the white rings, a
substantially greater radiation reflection is produced. Radiation
reflectivity sensor 45, mounted to housing 28, produces a voltage output
signal each time the higher radiation reflectivity of a white ring is
sensed.
In order to aid sensor 45 in producing a voltage output signal whenever a
white ring has been scanned, housing 28 is provided with light pipe 35
juxtaposed between slit 31 and sensor 45 to more completely direct and
concentrate the radiation reflected from the white ring to sensor 45. In
the preferred embodiment, light pipe 35 comprises a plurality of mirrors
46 which are peripherally mounted to the walls separatingly spacing sensor
45 from scanning slit 31. The incorporation of peripherally surrounding
mirrors on all four of the substantially vertical walls separating
scanning slit 31 from sensor 45 provides a narrow, elongated, rectangular
light transmission tunnel which comprises parallel facing closely spaced
reflecting surfaces, with perpendicularly disposed parallel facing
reflecting end surfaces. It is believed that the radiation reflection
produced when the scanning beam impinges upon a white concentric ring is
captured by the light pipe 35 and internally reflected along a plurality
of paths terminating randomly across the bottom of the light pipe, with a
substantial portion of the reflected radiation impinging upon sensor 45,
stabilizing or equalizing the signal-to-noise ratio across the entire
length of scanning slit 31. The incorporation of light pipe 35 is
extremely advantageous for aiding label reader 27 to accurately decode the
label regardless of the position along the length of slit 31 over which
the label passes.
Demountable housing 29 incorporates a sensor (not shown) while demountable
housing 30 incorporates an adjustable mirror (not shown). The mirror is
adjusted to reflect the laser beam to the sensor. As fully described
below, when an object has passed between and beyond the line between
housings 29 and 30, the impingement of the laser beam on the sensor causes
the sensor to transmit a signal to a "data ready" unit which enables the
information handling system to receive the next label scan.
INFORMATION HANDLING SYSTEM
A block diagram representing the electronic circuitry employed in the label
reader of this invention for the proper handling of the coded label signal
is shown in FIG. 4. The label information handling system comprises a
label scan reset unit 50, a label reflectivity decoder 51, a shift pulse
generator 52, shift register means 53, and a label information transfer
unit 54. Label information transfer unit 54 incorporates a label diameter
scan discriminator 56, comparator means 57, and a data ready and reset
unit 59.
In operation, label scan reset unit 50 enables the label information
handling system to receive reflected radiation corresponding to the
differing reflectivity levels of the different concentric rings of a
scanned label. Reset unit 50 is adaptable to several different
arrangements. Most commonly, reset unit 50 is incorporated into the data
storage unit and adapted to transmit a reset pulse as soon as the coded
label information has been transferred to data storage. Another common
arrangement is to incorporate beam transmitting and receiving means, such
as photocells, in reset unit 50, which causes the label information
handling system to be enabled whenever the beam is broken or else whenever
the beam is restored. With either arrangement, the label information
handling system will thus be ready to sense and properly process the
reflectivity levels of the coded label, and if desired provide a warning
signal whenever an item bearing a label has cleared the system without a
complete label reading.
Label reflectivity decoder 51 senses the radiation reflectivity levels of
the concentric rings of the label as the label is being scanned, shapes
this scanned signal into a clean pulse voltage signal, and transmits the
shaped voltage signal to shift register means 53. Label reflectivity
decoder 51 incorporates a radiation reflectivity level sensor and a signal
shaper. The sensor produces a voltage output representing the radiation
reflectivity levels of the coded label, and transmits this scanned signal
to the shaper. The shaper converts the scanned signal into a clean pulse
voltage signal so that the radiation reflectivity levels are well defined.
This shaped voltage signal is then transmitted to shift register means 53
for further processing.
Shift pulse generator 52 is connected to label reflectivity decoder 51 and
shift register means 53 and provides clocking pulses thereto in order to
assure the proper voltage signal transmission for each concentric ring of
the label scanned. Shift pulse generator 52 incorporates a pulse generator
and a pulse counter. The frequency of the pulse generator is selected for
the particular label scanning speed and label ring width. The counter
receives the pulses and is adapted to transmit a shift pulse at the pulse
count which substantially coincides with the midpoint in time of the scan
of each concentric ring. The shift pulse is transmitted to shift register
means 53 to assure proper recording of the shaped voltage signal.
Preferably, the counter is cleared with each voltage level change in the
shaped voltage signal in order to assure the desired synchronism between
shift pulses and the midpoint in time of the scan of each concentric ring.
In the preferred embodiment, shift register means 53 incorporates two
series-connected shift registers with each register incorporating storage
cells equal to the number of equal width concentric rings displayed on the
scanned label. As described above, the coded label information will be
completely read when a scan has been made substantially along any diameter
of the label. As a result, when this type of diametric scan has been made,
the label code will be read twice, one complete reading per radius, and
the shift registers will each have identical information stored therein,
with the cells of the second shift register containing the coded label
information from the first or inward radius portion of the scan.
Label information transfer unit 54 receives the shaped voltage signal,
which represents the coded label information, and must determine whether
or not this shaped voltage signal represents the entire label information
desired. As a label advances over the label reader, the label is
continuously scanned, with the coded information being sent to the label
information transfer unit 54. However, the early scans of a label do not
contain the entire coded information of the label since these scans are
merely taken along successive parallel chords of the label. It is not
until a scan is made substantially along a diameter of the label that the
entire label information will be recorded.
Label information transfer unit 54 determines when the entire label
information is recorded by establishing two conditions which must be met
before the information stored in the shift register means 53 will be
transferred to data handling interface 60. As mentioned above, when the
entire label information has been read, the two shift registers of shift
register means 53 will contain identical information. Therefore, label
information transfer unit 54 incorporates comparator means 57 which
provides a positive comparison signal when the shift registers of shift
register means 53 both contain identical information. Since it is possible
that coincidence will allow the two shift registers of shift register
means 53 to have stored therein identical signals without having a scan
substantially along a diameter of the label, label information transfer
unit 54 incorporates a label diameter scan discriminator 56, which
receives the positive comparison signal and further analyzes the
particular scan for determination of a label diameter scan.
DISCRIMINATOR FOR HIGH-REFLECTIVITY INNER DOT LABELS
The type of discriminator 56 employed in a particular transfer unit depends
upon the type of label being scanned. If label 20 incorporates an inner
dot, comprising a material having a radiation reflectivity level
substantially higher than the radiation reflectivity levels of the
concentric rings, discriminator 56 basically comprises a voltage detector
and an AND gate. The voltage detector receives the voltage signal
representing the radiation reflectivity levels of the concentric rings of
the label and is responsive to the substantially higher voltage signal
produced by the significantly higher reflectivity of the center circle
material. In response to this high level voltage signal, the voltage
detector transmits a positive label diameter signal to the AND gate, which
in turn transmits a positive data ready signal only when the positive
comparison signal is also present.
DISCRIMINATOR FOR LABELS WITHOUT HIGH REFLECTIVITY INNER DOTS
When the less expensive labels 25 which do not incorporate an inner dot
comprising the higher reflectivity material are employed, moving across
scanning slit 31, the label diameter scan discriminator 56 comprises
substantially more involved logic apparatus. Upon receipt of the positive
comparison signal from comparator means 57, discriminator 56 compares
consecutive scans to each other, and will transmit a positive label
diameter scan data ready signal only when certain conditions have been met
by the consecutive scans. Discriminator 56 compares each successive pair
of consecutive scanning signals for (1) the overall number of voltage
level transitions, and (2) the number of similar voltage level-producing
concentric rings at the label's center. When the number of similar voltage
level concentric rings scanned at the center of the label is less in the
second signal of the pair than in the first signal and the number of
voltage level transitions in the second signal of the pair has not
increased or when the number of voltage level transitions in the second
signal of the pair has decreased, the first signal of the pair must be a
label diameter scan. When these conditions are met, label diameter scan
discriminator 56 transmits a positive label diameter scan data ready
signal to data ready and reset unit 59.
Since discriminator 56 employs pairs of two successive label scans to
determine the label diameter scan and the desired scan resulting from the
discriminator analysis is the previous scan, shift register means 53 must
incorporate a third register which will store the square wave voltage
level signal from the preceding scan while the other two shift registers
store the following square wave voltage signal.
The positive data ready signal from discriminator 56 is transmitted to data
ready and reset unit 59, which in turn transmits a data transfer signal to
initiate the transfer of the data from shift register means 53 to data
handling interface 60. The data handling interface can be connected to a
data storage unit or data processing unit for use of the available data in
any desired manner.
LOGIC CIRCUITRY OF FIG. 5 FOR HIGH-REFLECTIVITY INNER DOT LABELS
A detailed logic circuit diagram of the label information handling system
of this invention for use with labels having the highly reflective
material as the center circle is shown in FIG. 5. In this embodiment,
label scan reset unit 50 comprises a sensor 142, an amplifier 143, and a
single shot one pulse generator 141. Label reflectivity decoder 51
comprises a reflectivity level sensor 115, a 120 CPS notch filter 125, to
eliminate fluctuation in light intensity of artificial background light
operating on 60 CPS A.C., an amplifier 123, a flip-flop 129, two single
shot one pulse generators 34 and 35, and an OR gate 36. Shift pulse
generator 52 comprises a pulse generator 137, a counter 132, a single shot
one pulse generator 33, and an AND gate 141. Shift register means 53
comprises shift registers 30 and 31.
Since this embodiment of the label information handling system is
preferably employed with the label having the highly reflective material
at the center thereof, the label information transfer unit 54 is
substantially simplified. The label diameter scan discriminator 56 of
transfer unit 54 comprises voltage detector 126, single shot one pulse
generator 127, and AND gate 128. Comparator means 57 comprises comparator
138 and single shot one pulse generator 139. The remainder of label
information transfer unit 54 merely comprises a data ready and reset
flip-flop 59.
OPERATION
During continuous label scanning operation, the data-ready and reset
flip-flop 59 will remain in the cleared condition until set by the
single-shot one pulse generator 141 triggered by the sensor 142 of the
label scan reset unit 50 through amplifier 143. A sensor adaptable to this
application is the Electro-Nuclear Laboratories, Inc. type SDA-004. A one
pulse generator adaptable to the application is a Schmidt Trigger, such as
Texas Instruments' SN 74121 described on pages 2-38 and 2-39 of their
Catalog CC 201. As described above in this embodiment, the presence of an
object over the narrow reading slit will prevent the laser beam directed
by the folding mirror from reaching the sensor 142. When the object has
passed over the reading slit, the sensor 142, amplifier 143, Schmidt
Trigger 141 act to set flip-flop 59, and the label reader is ready to read
another label.
With the label information handling system ready, the laser beam scans
across a chord of the label with the reflected light scattering uniformly
in all directions. The reflection produced is sensed by reflectivity level
sensor 115 and transformed into a voltage output signal. The signal at the
output of the amplifier 123, as a result of the laser beam scanning the
label through the center, after the detection of the variations in
reflected light by sensor 115 and the filtering of 120 cycle fluctuation
of artificial background light by filter 125, is shown in diagram (a) of
FIG. 6.
One sensor adapted to this application is the type SDA-004 silicon
photodiode/operational amplifier combination built in a single TO-5
package supplied by Electro-Nuclear Laboratories, Inc., Menlo Park,
California. The silicon photodiode type sensors will detect very small
variations in light intensity in the presence of extremely bright
background light. Artificial background light such as incadescent or
fluorescent light operating on 60 cycles A.C. introduces 120 cycle | | |
