Note: Descriptions are shown in the official language in which they were submitted.
1 BACKGROUND OF THE INVENTION
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The present lnvantion relates to the optical
scanning of a code in series on a reglet and made up of
retro-reflected elements at regular intervals. Sliding
runners on the reglet each conceal a retro-reflecting
mark and by their position indicate the code.
When reading the article code on a tote for
transferring articles along a conveyor, the code typically
passes a stationary code reader such that tbe elements
making up each code bit occur in time sequence or serial
sequence. In order to read the entire code accurately,
typically storage means, such as a shift register, are
provided which sequentially receives each code bit and
stores the bit until the entire code is read and stcred~
Once this is done, the computer interface or whatever
control utilizing the code reads the entire code out in
parallel form (iOe. each bit simultaneously).
In order to shift each code bit serially into a
storage device such as the shift register, it is necessary
that a clock pulse be employed which has the effect of
; permitting each bit to be read and stored. There e~ist
two generally known ways to generate clock pulses which
of course, must be in precise timed relationship to the
code and, therefore, must in some way be related to the
code strip carried by the tote. The first manner is to
utilize a pulse generator driven by the conveyor which
can be utilized since the speed at which the code on the
tote passes the detectors is directly related to the con-
veyor speed. Another method which does not rely on con-
veyor speed information is to place a separate clock strip
on the coded area on the tote. This, of course, requires
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3~'~
l an additional detector and assoclated circuitry, plus
additional coding elements~
SUMMARY OF THE INVENTION
In general, the invention refers ItO a procedure
of scanning coding positions of a binary co~e strip by
reading the distribution in the spacing oE the code po-
sitions and also obtaining a timing signal used for
clocking the serially read code into a memory. The
scanning system includes at least two detectors spaced
from one another a distance to simultaneously read adjacent
code elements and lying in a plane parallel to the directLon
of movement of the code strip~
The invention can especially be applLed, but not
exclusively, to the optical reading of coded reglets
carried by moving bodies to be handled for effectively
identifying the aforesaid moving bodies.
Other characteristics and advantages of this
invention will become apparent from the following descrip-~
tion and by reference to the attached drawings in which:
~` 20 BRIEF DESCRIPTION OF THE DRAWINGS
Pigure l is a diagram representing a scanning
device according to one form of the invention; and
Figure 2 is a diagram of another form of the
scanning device of the invention~
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
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In the form of the invention shown in Fig. 1, a
code strip includes a plurality of reflective elements
R and r mounted to a reglet B{in turn positioned on an
article. Runners A slidably mounted within the reglet can
be moved to selectively block elements R to deflne a
predetermined binary code. The runners A cannot hide
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1 the extreme retro-reflective selections r of the reglet B,
nor two consecutive retro_reflective selections R (hence
two consecutive code positions~ since blocking studs P
prevent the passage of the runners to obstruct the ele-
ments r.
The scanning device used for reacling the code
strip includes two spaced reflex photoelectric cells C.
These cells have their output coupled to the inputs of an
OR gate OU through filter circuits F. One of the cells C
has its output coupled to the input of a memory circuit D
which in the preferred embodiment consists cf a~-shlt
register. The output of the OR gate is coupled to a mono-
stable multivibrator M havin& its output coupled to a
; clock input terminal of the shift register D. In the
form of the invention seen in Fig.-2, the scanning device
includes three reflex photoelectric cells C, and the
runners A are able to hide any retro-reflective selections
R.
The cells C in both embodlments have their
optical axes parallel to the code strip and are spaced
from each other by the sam~ distance separating two
successive retro-re1ective elements R and their beams
normally cut the coded surface of the reglet. In some em-
bodiments, the cell spacing can be different than that of
the code element as long as their field of view is di-
rected at successi~e code elements for sinultaneously
reading of two or more code elements.
In both embodiments when a reglet passes in
~ front of the scanning device (or vice versa), at least
- 30 one cell is always found in front of the unhidden retro-
reflected code element. Thus, a clock pulse indicating
l the reading of a new code element is always developed
by the OR gate and applied to the shift register D (or its
equivalsnt, programed in case of direct entrance on a
computer). The code displayed on the reglet will thus be
entered in the aforesaid register at the end of the passage
of the reglet) so that one is able to use as a self-timer
the signal from the OR gate. The multivibrator M delays
the clock pulse slightly and narrows it somewhat so that
the shift register will read the code eleme~t only during
a brief interval near the center of the occurrence o~an
output pulse from the cell coupled to the input of the
register D.
The control function and the outputing of the
code entered into the shift register D takes place when a
control cell C indicates the end of the passage of the
moving body on which is fixed the coded reglet. `The
output of cell C, in either embodiment, can be applied
to a peripheral utili~ation device such as a diverter
control of a sorting conveyor or the like.
The concern of the coded scanning device of the
; invention rests in the fact that the device is arranged so
it can reliabLy read all the possible codes of the reglet
with a limited number of readers at the lowest cost since
the electrical circuits are themselves very simple.
It is to be clearly understood that this inven-
tion has been described and represented only as a preferred
example of the invention and that various modiflcations to
the preferred embodiment can be made. Thus for example,
the code elements and sensors need not be opticalO Also
the detectors could be moved with the code elements sta-
tionaryO These and o~her modifications to the preferred
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1 embodiments will, however, fall within the scope and
spirit o the invention as deined by the appendqd
claims.
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