U.S. patent number 3,725,867 [Application Number 05/030,840] was granted by the patent office on 1973-04-03 for a selective control system for dispatching articles on a conveyor.
This patent grant is currently assigned to Westinghouse Brake and Signal Company Limited. Invention is credited to John H. Jordan.
United States Patent |
3,725,867 |
Jordan |
April 3, 1973 |
A SELECTIVE CONTROL SYSTEM FOR DISPATCHING ARTICLES ON A
CONVEYOR
Abstract
A control system is proposed which is of more special but not
exclusive application to the dispatching of articles on a conveyor
and where the conveyor can be carrying many objects at one time
which are destined for discharge at different points. Dispatching
of an object is accompanied by entry into a computer type store of
a count representation and a representation which identifies the
action to be performed when the count representation has been
decremented to a significant value. Decrementing of the count
representation is effected after predetermined elapsed intervals or
events which in the case of the conveyor system correspond to set
distances covered by the conveyor.
Inventors: |
Jordan; John H. (London,
EN) |
Assignee: |
Westinghouse Brake and Signal
Company Limited (London, EN)
|
Family
ID: |
10180372 |
Appl.
No.: |
05/030,840 |
Filed: |
April 22, 1970 |
Foreign Application Priority Data
|
|
|
|
|
May 2, 1969 [GB] |
|
|
22,498/69 |
|
Current U.S.
Class: |
700/223;
198/349.95 |
Current CPC
Class: |
B65G
47/50 (20130101); B07C 3/006 (20130101) |
Current International
Class: |
B07C
3/00 (20060101); B65G 47/50 (20060101); G06k
017/00 (); G11b 027/14 (); G05b 019/30 () |
Field of
Search: |
;340/172.5
;209/74,114,122 ;214/11 ;118/2 ;307/40 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Henon; Paul J.
Assistant Examiner: Rhoads; Jan E.
Claims
Having thus described our invention what we claim is:
1. A control system for an object routing apparatus for controlling
diverting of objects from a conveyor, said system comprising: main
storage means for providing distinct storage locations for at least
one count representation for each of a plurality of objects to be
successively routed, said at least one count representation
comprising a first count representation predetermining the number
of intervals which is to elapse between a predetermined point and a
further point at which an action is to be initiated by which the
object is to be diverted from the conveyor, and at least one action
representation by which the action to be initiated is to be
identified. said at least one action representation comprising a
first action representation representing a diverting action whereby
an object is diverted from the conveyor; means for successively
recording a said first count representation in said storage
locations in said main storage means for each of said plurality of
objects and for recording a said first action representation in
said storage locations in said storage means by which the action to
be initiated is to be identified; means responsive to the elapsing
of successive of said intervals for reading out said first count
representations from the corresponding storage locations, for
decrementing said first count representations and for reading said
first count representations back into said storage locations;
comparison means for comparing the decremented first count
representations with a predetermined reference and for producing an
output signal when a decremented count matches said predetermined
reference; response means, responsive to the said output signal
produced by said comparison means, for selecting a diverting action
to be initiated at said further point when a first decremented
count representation produces a match; and diverting means, located
at said further point, for diverting an object from the conveyor at
said further point responsive to the selection of a diverting
action.
2. A control system as claimed in claim 1 wherein said recording
means comprises means for recording a second count representation
in said storage means for each of said plurality of objects, said
second count representation determining the number of intervals
which is to elapse between the passing of the object between said
predetermined point and a point at which a further action is to be
initiated, and for recording in said storage means a second action
representation by which the action to be initiated is identifiable,
said second action representation representing a closing action
whereby diverting of an object from the conveyor is prevented, said
decrementing means decrementing said second count representation
responsive to the elapsing of said successive intervals, said
comparison means comparing the decremented second count
representations with a further predetermined reference and
producing a further output signal when a decremented second count
matches said further reference, said response means acting
responsive to the further output signal produced by said comparison
means to select a closing action when a second decremented count
representation produces a match, and said diverting means
preventing an object from being diverted from said conveyor at said
further point responsive to the selection of a closing action.
3. A control system as claimed in claim 2 further comprising buffer
storage means for storing the count and action representations
pertaining to a last object, further comparison means for comparing
an action representation stored in said buffer storage means with
the action representation pertaining to a present object and, in
the event of these said action representations being the same,
retaining the count and action representations in said buffer
storage means, and means for applying the count representation and
action representation from said buffer storage means to said main
storage means when said action representations are different.
4. A control system as claimed in claim 2 wherein said recording
means includes independent count representation generating means
for generating independent count representations so that the count
representations pertaining to different first and second actions
are independently predeterminable so as to take account of
operating characteristics of a selected said diverting means.
5. A control system as claimed in claim 2 further comprising an
input scanner comprising a clock signal generator for producing a
clock signal the frequency of which is high in relation to that of
said intervals, means responsive to said clock signals from said
generator for alternately scanning two inputs one of which
corresponds to the passage of an object past said predetermined
point and the other of which corresponds to successive said elapsed
intervals, and means for discretely initiating an output signal in
which representations pertaining to an object are recorded in said
storage means or an output signal in which said decrementing is
effected, respectively.
6. A control system as claimed in claim 2 wherein said diverting
means comprises gate means which open responsive to the first
action representation being selected by said responsive means to
permit the discharge of objects from the conveyor and which close
responsive to the second action representation being selected by
said responsive means to prevent the discharge of objects from the
conveyor.
7. A control system as claimed in claim 2 wherein said main storage
means comprises a magnetic core store, said recording means
comprising an address counter for recording the count
representations in alternate addresses and representations of
actions in intervening addresses, the intervening addresses being
arranged to store representations of means for performing actions
and the respective action, and the alternate addresses being
arranged to have recorded therein the representations of the action
to be performed by the action performing means identifiable by
representations stored in respective intervening addresses.
Description
FIELD OF THE INVENTION
This invention relates to control systems for controlling actions
with regard to objects at points along their route and relates more
especially but by no means exclusively to apparatus for controlling
a parcel sorting machine.
BACKGROUND OF THE INVENTION
In control apparatus for controlling actions in respect of routed
objects at points along their route, such for example as in a
parcel sorting machine of the type employed in Post Office Sorting
Departments, it is desirable for the facility to be provided to
enable an operator to place an object on a conveyor and operate a
key indicative of the required destination or route to determine at
what point the object is to be released from the conveyor.
A problem exists in this connection in that it is normally required
that a substantial number of objects may be travelling
simultaneously along the conveyor and it is therefore necessary
that actions pertaining to the objects, in the form of opening of
selected gates shall be effected selectively at the required
positions of the conveyor.
It may readily be appreciated also, that where in the event, for
example, of a parcel for a destination proceeding along a conveyor
in a parcel sorting machine, this parcel is followed by a further
parcel for a different destination, a desired one of a series of
gates provided along the conveyor is required to open when reached
by the first parcel to allow the first parcel to pass through it
but to close again before the following parcel can pass through
it.
Further, it may be desirable in certain forms of sorting apparatus,
to arrange that a gate opened for the passage of a first object may
remain open in the event of the first object being followed
immediately by a further object destined for the same gate.
SUMMARY OF THE INVENTION
According to the present invention there is provided a control
system for controlling actions with regard to objects travelling
along a predetermined route including main storage means, means for
successively recording in said storage means in respect of each of
a plurality of successive objects a first count representation for
predetermining the number of intervals to elapse between the object
passing between a predetermined point and a point at which an
action is to be initiated, for recording a first action
representation by which the action to be initiated is identifiable,
decrementing means responsive to successive such intervals elapsing
for decrementing the first count representation and response means
responsive to a predetermined significant decremented
representation being attained for initiating readout of the action
representation and applying it to select the respective action to
be initiated.
It is to be understood that elapsed intervals may be intervals of
fixed time, distance or mere intervals between occurring
events.
The system may also incorporate means for setting up in registers
representations of the count representation and the respective
action representation for an object being committed to the
apparatus and the means for making a comparison of the action
representation set up with a stored action representation for the
previously committed object to enable in the event of the compared
representations being the same the action effective on said
previous object to be effective also on the object being
committed.
Where such means for making a comparison as are referred to in the
previous paragraph are provided, the apparatus may be operable in
the event of said action representations not being the same, to
read into a first location of the storage device the count
representation corresponding to the previous object and into the
respective second location a representation of the action to be
removed.
First and second buffer storage means may also be provided for
storing count and action representations respectively corresponding
to the previous object, the apparatus being operable following said
comparison for utilizing said buffer stores to receive the count
and action representation for the object being committed for
subsequent non-destructive read out into respective first and
second address locations of the storage means.
The logical functioning of the apparatus may be effected by
providing means for generating a repetitive clock signal the
frequency of which is many times greater than the rate of
occurrence of said successive intervals, a scanner circuit being
responsive to said clock signals for alternately scanning a number
of inputs at which signals appear corresponding respectively to the
passage of an object past a start point (preferably said
predetermined point) and the passage of said successive intervals
to initiate the appropriate logical functioning of the
apparatus.
It may further be mentioned that the representations of the actions
to be performed with regard to the respective objects may
preferably comprise two parts, one part representative of the
location of an action and the other part representative of the
action to be effected at the respective location.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the present invention may be more clearly understood
and readily carried into effect, the same will be further described
by way of example, with reference to the accompanying drawings in
which:
FIG. 1 illustrates in diagrammatical form a keyboard of a
Post-Office Sorter together with associated interface and input
circuits for object routing apparatus for controlling a Post Office
type Sorter,
FIG. 2 illustrates a scanning circuit operable to select the
appropriate logical functioning of the apparatus,
FIG. 3 illustrates input cycle control apparatus which governs the
initial reading in of representations to the storage means,
FIG. 4 illustrates output controlling apparatus which governs the
initiation and selection of the appropriate action to be taken on
objects, and
FIG. 5 illustrates logic circuit symbols used in FIGS. 1 to 4.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Before details of description of the specific apparatus is given
which is illustrated in the drawings, it is convenient to discuss
the apparatus in general terms. The specific apparatus illustrated
is intended to control a Post Office Sorting Machine which
comprises a belt conveyor along the sides of a sloping belt of
which there are provided at spaced intervals, outlet gates which
are required to be opened to permit the discharge of parcels from
the conveyor to correct further routes or bags.
In order to achieve the above result, the operator is provided with
a keyboard and on committing a parcel to the conveyor, an
appropriate destination key is pressed and this is required to
initiate the opening of the appropriate gate from the conveyor when
the parcel in question arrives thereat. If moreover, the next
parcel on the conveyor is destined for the same gate, it is
desirable but not essential that this gate remain open to accept
the next parcel also.
The apparatus operates by utilizing a main storage means in the
form of a magnetic core storage device and operates by counting
down codes stored in locations in the storage device corresponding
to the distance from a predetermined point determined by the
passage of a parcel past a synchronizing unit to the discharge
gates of the conveyor. The relevant initial count for a gate is
entered by the apparatus into the storage device whenever a parcel
is committed to the conveyor, an appropriate key is depressed on
the keyboard and a synchronizing signal is received to indicate
that the parcel has reached a fixed reference point on the
conveyor. All the count representations in the storage means are
decremented by a specified amount after the passage of the conveyor
through each successive interval, of say, 2 inches and when the
decremented count in any particular address location in the storage
means reaches a significant count (say zero), a corresponding
action representation also stored in the storage means is read out
to initiate the opening of the appropriate gate of the
conveyor.
Two features which may be included but which are not always
essential may now be briefly mentioned:
When the next parcel is committed to the conveyor, similar count
and action representations may be entered to the storage means in a
similar manner and these may be used to initiate the closing of the
gate for the first parcel before the second parcel reaches it.
The apparatus may also be provided with means whereby each count
representation may be used more than once to initiate actions which
are separated by fixed intervals of time or distance. For example
if the action to be performed consists of a two-part motion then
two different count levels may be recognized as significant for the
initiation of the two different parts of the action, and/or two
different levels may be recognized as significant for the
initiation of open and/or close instructions, thereby providing a
means of adjusting the logical timing to allow for time delays in
mechanical operations.
From the foregoing it may be appreciated that two basic logical
funtions have to be performed by the apparatus. Firstly, when a
parcel is passing a synchronization point at the start of its
journey down the conveyor, after depression of an appropriate key
by the operator, information corresponding to the depression of the
key is required to be stored in the storage means. Secondly, after
the passage of the conveyor over each successive predetermined
interval of say, 2 inches, the apparatus is required to decrement
the count representations in the storage means, correspondingly to
the intervals covered and to look at the decremented count
representations to ascertain whether a significant count at which
an action should be initiated has been reached.
As will be seen hereafter, the initiation of these actions is
effected by a cycle access scanner which is illustrated in FIG. 2
and this looks in turn for a 2-inch movement pulse from the
conveyor and for a synchronizing pulse from a photo-electric
detector which detects the presence of a parcel at the
predetermined start or reference point for the conveyor. The
scanner scans the inputs at a frequency determined by a clock pulse
generator which is much higher than the frequency of occurrence of
the predetermined intervals associated with the conveyor. When
either signal is sensed, the cycle access scanner interrupts
scanning and drives the appropriate logical function.
Considering in general terms the input cycle referred to above,
when a keyboard key is operated, a "code now" lamp, which is shown
in FIG. 1, is extinguished and the keyboard is inhibited from
further operations and two code words are generated. The first of
these code words is a count representation which determines the
necessary conveyor travel before the associated parcel is to be
discharged. The second code word contains information as to which
of the conveyor gates is to be operated for this particular parcel
and constitutes part of the subsequently to be produced action
representation. It may be useful moreover at this point to mention
that action representations stored in the storage means comprise a
destination word which indicates which of the conveyor gates is to
be operated for a particular parcel and also an instruction as to
what the nature of the operation (i.e. open or close) is. The two
words set in by the keyboard are then held to await the arrival of
a synchronizing pulse indicating the passage of the parcel past a
predetermined point. In addition, a cancel key is provided which
the operator can depress in the event of making an erroneous
keyboard operation to return the stored information to zero.
When the synchronizing pulse is received to direct the cycle access
scanner to initiate an input cycle, the destination word for the
present parcel is compared with a stored destination word for the
previous parcel and if these two words are the same, that is there
are two consecutive parcels on the conveyor for the same
destination, no further action is required to be taken and the
cycle access scanner is released again to the scanning mode of
operation. If however, the two destination words are different,
stored count and destination words for the previous parcel are
written into respective core locations the latter word also being
accompanied by two command code bits to indicate a "close" action
command. Thus the core store will now carry in respect of the
previous parcel not only a count, destination and action code for
opening a gate but also a count destination and action code for
closing that gate. The count and destination words for the present
parcel are then read into buffer stores which previously held the
previous parcel information and also into the next two address
locations in the core storage device. The access scanner is then
released again to the scanning mode.
Referring now to output cycle operation in general terms, when the
cycle access scanner is instructed by receiving an input pulse
corresponding to the passage of a predetermined interval of
distance, each count word in the storage device is decremented and
checked and if the result of the check is significant and indicates
that a point of the conveyor passage has been reached where an
action is to be effected, the next address in the core storage
device is read out and this carries the destination and action word
by way of an "action" representation. The code read out is utilized
to initiate the appropriate opening or closing action for the
conveyor gate in question. It will be recalled that all the count
words in the storage means are decremented at each predetermined
interval of the conveyor movement and following each such output
cycle, the access scanner is released to its scanning mode.
From the foregoing and particularly with reference to the general
outline of the operation of the input cycle, it may be appreciated
that the core storage device is required, in the event of one
parcel on the conveyor being followed by another parcel destined
for a gate which is different from the gate for which the first
parcel is destined, to provide count and action representation
storage for the opening of the first gate and the closing of the
first gate. Accordingly, the storage device is required to have a
maximum of two count storage locations for each possible parcel on
the conveyor and two action storage locations for each possible
parcel on the conveyor. Thus, for a conveyor which from a practical
point of view will carry no more than 64 parcels, the storage
device is required to have 256 storage locations or addresses. It
is convenient moreover for the count code representations to be
stored in "even" addresses in the storage device and for
destination and command or action representations to be stored in
"odd" addresses of the storage means.
Bearing in mind the above, it will be appreciated that for the
purposes of the output cycle operation, the apparatus is required
to decrement the codes only in the even locations of the storage
device. Further, the apparatus is arranged so that for a count
representation stored at an even location of the storage device,
the corresponding action or destination and command representation
is stored in the next odd location in the storage device.
In order to provide the selection of the locations within the
storage device, two separate address location counters, which may
be referred to as AC1 and AC2, not shown in the drawings, are
provided. AC1 provides that instructions regarding successive
parcels loaded to the conveyor will be entered to successive
locations of the storage device. AC2 is independent of AC1 and
controls the decrementing of count representations in all "even"
locations during output cycles and AC2 also operates to identify
the location of an appropriate action representation when a
significant count is attained.
Reference may now be made in greater detail to the present example
of the invention with reference to FIGS. 1 to 4 of the drawings
referred to above. However, reference to FIG. 5 will first clarify
the logical symbols used.
Referring to FIG. 5 the symbol shown at (a) is a normal relay,
symbol (b) is a slow to release relay and the symbol at (c) is a
slow to pick relay.
The relay contacts shown at (d) and (e) are normally open and
normally closed (back) contacts.
The symbol (f) represents an AND gate in operation of which the
output is a 1 output only when all inputs are 1 inputs. The symbol
(g) represents an OR gate in operation of which the output is a 1
when any input is a 1 input.
The symbol (h) represents a bistable toggle or latch, in operation
of which an input at S going momentarily to a 1 condition sets
output Q to a 1 output and sets output Q to a 0 output. An input R
going momentarily to a 1 condition sets output Q to a 0 state and
sets output Q to a 1 state.
Symbols (i), (j) and (k) are timing elements. Symbol (i) represents
an element which in operation produces a fixed pulse of duration
.delta. from the beginning of an input signal. Symbol (j) is an
element which in operation produces a fixed pulse of duration
.delta. from the trailing edge of an input signal and element (K)
in operation produces after a fixed delay .delta.1 from the leading
edge of an input signal, a fixed pulse of duration .delta.2. These
functions are illustrated diagrammatically beneath the symbols (i),
(j) and (k).
Symbol (l) represents an inversion element which produces a 1
output in response to 0 input and vice versa.
Symbol (m) represents wherever shown, a positive supply point with
respect to common or ground.
Symbol (n) represents an indicator lamp.
For the sake of clarity, it is to be understood that a logic state
1 is a voltage level approximating to the supply voltage and a
logic state 0 corresponds to ground voltage.
Referring to FIG. 1, this shows a count generating matrix CGM and a
destination generating matrix DGM connected to a keyboard having
keys, K1 to K50, K50 being a "cancel" key. Also shown is the "code
now" lamp referred to above and the power supply terminals denoted
P for convenience. In addition, a number of relays are provided
which are best referred to in discussion of the operation. The
relays and switches are shown in the quiescent or de-energized
condition and on applying the power to the circuit, provided that
no keys on the keyboard are operated, the "all keys released" relay
KRR will be operated, the contacts GR1 of the guard relay GR and
the keys K1 to K50 being in the de-energized condition. The matrix
CGM has associated registers with relays CR1 to CR.12. The matrix
DGM has register relays DR1 to DR7 and provided there is no stray
information on the registers, so that the above mentioned register
relays are all de-energized and the contacts thereof are in the
condition shown, the closure of the relay KRR energizes the guard
relay GR over the contacts SGR/2 of the synchronizing guard relay
SGR. The guard relay is therefore latched over its contacts GR/4
and the operation of contacts GR/3 de-energizes the cancel relay
CNR, any previous cancel function now being complete. Operation of
contacts GR/5 to the energized condition and de-energization of the
cancel relay open-circuits the "end of cycle" relay LCR which
therefore enables the power supply to be connected to the keyboard
via GR/1, CNR/1 and ECR/1. Also, the latching on of the guard relay
GR disables the current path to the relay KRR the function of which
is now completed. The "code now" lamp is also illuminated via
contacts GR/2, CNR/1 and ECR/1.
Assuming now that the operator depresses one of the keys K1 to K49
of the keyboard and admits a parcel to the conveyor, appropriate
count codes and destination codes are registered in the register
relays CR1 to CR 12 and DR1 to DR7 and by virtue of operation of
one or more of these relays, the guard relay GR is de-energized and
the power supply to the keyboard is again inhibited. When the
synchronization relay detector SD is operated, the synchronization
pulse energizes the synchronization guard relay SGR/ and this is
latched over SGR/1. It will be understood that detector SD is
operated by the parcel traversing a fixed detector located at a
predetermined point along the conveyor route. Operation of the
relay SGR/2 to the open condition also contributes to the keyboard
being inhibited by preventing energization of the guard relay GR.
After a slight delay in picking, the slow to pick "synchronization"
relay SR picks and operation of contacts SR/1 removes the pick
supply from SGR which is now held over SGR/1 until completion of
the cycle. Also, operation of contact SR/2 operates the
synchronization toggle ST which sets the input cycle demand toggle
CT to produce an output signal on the input cycle request line 1CR.
On application of the input cycle request signal to the cycle
access scanner, the scanner subsequently produces an "input cycle
on" signal on the "1CO" line and this signal operates the gates
G19/1-7 to enter the "destination" representation to the input
cycle, renders the gate G21 operable by a signal CD to be referred
to in connection with FIG. 3 and starts the input cycle.
Considering now the input cycle operation of the circuit
arrangement in FIG. 3, the signal 1CO as referred to above
satisfies the gates G19/1 to G19/7 in the input interface circuit
and gates G14/1 to G14/7 (shown for simplicity in the drawing as a
single gate G14) interrogate a seven bit comparator circuit which
then operates to compare the "destination" code for the previous
parcel, if any, stored in buffer store B1 and the destination word
which is now fed in via gates G19/1 to G19/7 corresponding to the
present parcel. If the two parcels are for the same destination, it
is not necessary to take any action for, as explained previously,
an operation of a conveyor gate to receive the first parcel can
persist to receive the second parcel without any particular
instruction to the machine. The comparator therefore, under these
conditions, provides an output to the OR gate G16 to produce an
"input cycle finish" signal on the line marked 1CF in the drawing.
The effect of this signal will be appreciated hereafter.
If the two parcels are for different destinations, the comparator
produces an output signal to set the bistable circuit B4 to the on
condition to produce an input to the OR gate G8 which therefore
renders the gates G9/1 to G9/12 (again shown as a single gate)
operative to gate from buffer store A the "count" word for the
previous parcel (if any) on the conveyor to the next available even
address or the core storage device. On completion of read-in of
this "count" word, the address counter associated with the
selection of addresses for the input cycle is operated to set the
next available address in readiness for the next incoming count
information thereto. Thus, the address counter can be said to be
incremented by one.
Following this, the gate G10 resets the buffer store A as indicated
by the connection therefrom in the drawing, to a zero condition and
sets the buffer store B2 to a condition 1-0 to represent a "closed"
gate command for the conveyor gates. Setting of the buffer store B2
to the condition 0-1 can alternatively be effected when required to
represent the "open" gate command for the conveyor. The OR gate G13
is then satisfied by the read-in signal to the buffer B2 and
operates to satisfy the gates G15/1 to G15/9 (again shown as a
single gate for convenience) to gate the "destination" word and the
"close" gate command as a combined "action" word from the buffer
stores B1 and B2 into the next "odd" address location in the core
store. On completion of this the address counter is again
incremented by one and the same signal is utilized to reset the
buffer store B2 to a zero condition. Following incrementing of the
address counter, the AND gate G17 is satisfied and the buffer store
B1 is reset to zero, the bistable circuit B4 also being set to the
original condition.
Resetting of the bistable circuit B4 provides an input signal CD to
the gate G21 which therefore gates the "count" word for the present
parcel into the buffer store A and the OR gate G8 is subsequently
satisfied by a delayed pulse to write the contents of the buffer
store A into the next core location of the storage device. When the
reading operation is complete, the address counter is again
incremented. Gate G11 is then satisfied and as mentioned previously
sets buffer store B2 to 0-1 which represents an "open" instruction.
The operation of Gate G11 also satisfies gates G12/1-7 which
operate to enter the "destination" word for the present parcel into
the buffer store B1. As before G13 is satisfied and after a slight
delay, the contents of the two buffer stores B1 and B2, are
combined as an "action representation" and are read into the next
core address of the storage device via gates G15/1-9. The buffer
store B2 is subsequently again reset to the zero condition and the
address counter for the storage device is again incremented. The
gate G18 is now satisfied by virtue of B4 being in the reset
condition and the "input cycle finish" cycle 1CF is produced.
It may now be appreciated that as foreshadowed previously, the
input cycle operated logic has read into the core storage device, a
"count" word in one location (address say 20) and a combined
"close" and "destination" word in the next location (address 21),
both words referring to the last parcel entering the machine, and a
"count" word in the next location (address 22) and a combined
"open" and "destination" word in the next location (address 23),
both the latter words referring to the parcel just entering the
machine. It will be observed from the sequence of operation
therefore that in each case, the "count" word is read into an
"even" address location of the core storage device and the "action"
words are read into the "odd" address locations of the storage
device.
It is convenient now to refer to the logical circuit arrangement
outlined in the diagram of FIG. 4. Again, it can be assumed that
the cycle access scanner has reached a point at which a 2-inch
movement of the conveyor belt has been reached and as soon as the
cycle access scanner is in a position to revert to output cycle
operation, the cycle access scanner produces an "output cycle on"
request signal to the line labelled OCO in FIG. 4 in a manner to be
described hereafter the immediate effect of this is to set a
further address counter AC2 not shown to the zero condition in
readiness for the commencement of sequential operation on the
"count" representations at all the even locations of the core
storage device.
The successive operations are illustrated for convenience and ease
of understanding by blocks in the diagram of FIG. 4. Thus, on
resetting of the address counter to the zero, the OR gate in the
output lead thereof, passes a read core command and following a
parity check, if satisfactory, the contents of the first core
location are decremented by one unit (corresponding to a 2-inch
step of the belt) the parity is regenerated and the code is reread
into the same core location. In addition, the decremented code is
decoded and checked in the checking circuit CC for the presence of
a significant level, that is, a count level corresponding to the
arrival of a parcel at a point at which a gate is to be opened or
closed.
Assuming that the check of the count is not significant, the
checking circuit produces an output to the AND gate G22 and the
output thereof increments the address counter and subsequently
applies an input to the OR gate G31.
At this point reference may be made to the situation where a count
in the checking circuit proves to be a significant count, that is,
it represents a level at which an action is required to be
effected, one of the decoder outputs satisfies the OR gate G23 and
the address counter is incremented so that the address which is now
set by the address counter is the next following odd address in the
core storage device and this address is read out into a buffer
store denoted D in FIG. 4. The read out representation is therefore
an "action" representation consisting of a "destination" word and
an "open" or "close" instruction.
The instruction bits from the buffer store D are decoded to produce
an open or close command on the appropriate output lead and the
"destination" bits are decoded to one of 49 separate lines (the
number of gates in this case associated with the conveyor) to
select the gate to be acted upon. For simplicity only one such line
is shown.
The "count" level producing a particular output A1 (say) from the
decoder is arranged to be the highest significant count and
corresponds in this embodiment to a "close" gate command.
If the instruction bits decode to produce a "close" instruction and
the count level gives rise to an output A1 of the decoder, the AND
gate G27 is satisfied and G29 resets the output bistable OB (of
which only one OB1 of the 49 in this case is shown) corresponding
to the decoded destination.
If the instruction bits decode to give rise to an "open"
instruction and the decoded "count" level is A2 (say), the gate G24
is satisfied and the output bistable in question is set to the "on"
position by the gate G28. Outputs from G28 or G29 are operable via
OR gate G30 to produce a signal to "zero" the destination word from
the respective location in the core store. The end of zeroing this
operation provides an "input" to the OR gate G31. Under these
conditions therefore the appropriate instruction is applied by the
respective output bistable (via connection not shown) to the
requisite gate of the conveyor. The core store is subsequently
incremented by virtue of the output from the gate G31 (which latter
action is also effective in the event of a non-significant count
level being detected) and assuming it is not at the maximum count,
the decoder proceeds to read out the next odd location of the core
storage device and the sequence repeats right through each odd
location until the address counter decodes to the maximum value. At
this point, the signal OCF representing the finish of the output
cycle is produced on the line so marked in FIG. 4.
In FIG. 4 the count decoder and comparator CC is shown having two
output points A1 and A2 and two further output points B1 and B2. A1
and A2 correspond as indicated above, to significant counts for
"close" and "open" actions respectively for the conveyor gates. If,
as is often required, groups of gates are to be operated, that is a
given destination comprises more than one gate, the output points
B1 and B2 corresponding to further significant counts are utilized
in respect of "close" and "open" commands respectively for the
further gate or gates, operation being thereby subjected to delay
as compared with operation of the A gates. In this case similar
gates and control logic associated with the decoder are provided.
Further, the "write" zero command for the action representation in
the core location is postponed until the significant B1 or B2
output has been effective.
In the interest of understanding of the more important and
significant aspects of the operation of the arrangement, the
description of the cycle access scanner has been postponed and will
now briefly be referred to with reference to FIG. 2.
The cycle access scanner has two basic inputs, one being the signal
ICR derived from the interface circuit illustrated in FIG. 1 and
occurring following operation of the keyboard and synchronization
detector SD. The other basic input to the cycle access scanner is a
belt movement pulse which appears on line B.M.P and occurs for
every two inch movement of the conveyor belt. This can be derived
from a suitable switching device coupled to the belt drive
mechanism. The cycle access/scanner further receives at the input
marked STEP, clock pulses from a multi-vibrator not shown, the
nominal frequency of which in this case is about 10 KC/S but can be
varied to suit the applications. As mentioned previously, the clock
pulses operate to alternately look at the ICR and BMP line to
initiate an appropriate input or output cycle as soon as it is
opportune to do so.
A toggle circuit B3 is connected to follow the state of the belt
movement pulses and each time B3 sets, a pulse is generated via a
fixed pulse width generating device. This operates a bistable
circuit B2 which is resettable at the end of an output cycle by the
OCF signal regardless of the state of B3.
Assuming there is no input on the ICR line, and that bistable
circuit B2 is in the unoperated or reset condition, the OR gate G2
produces no output and therefore, by virtue of the inverter 1, the
bistable circuit B1 is operated. Successive step pulses
corresponding to the leading edge of the clock waveform, satisfy
the gate G5 and set the bistable flip-flop circuit JK alternately
from one state to the other. When B2 is operated, the next output
from the right hand side of the bistable JK satisfies the gate G1/1
and a corresponding interrogation pulse satisfied the gate G3/1 but
not the gate G3/2. Therefore the reset state of the bistable B1 is
produced. This inhibits the gate G5 to inhibit further step pulses
from the bistable flip-flop JK. Moreover, with the bistable B1 in
the reset condition and the gate G1/1 satisfied, the gate G4/1 is
satisfied which gives a signal representing output cycle on, on the
line marked OCO. As will be recalled, this constitutes an input to
the output cycle logic described in the foregoing with reference to
FIG. 4. On completion of the output cycle, the signal OCF is
produced as referred to previously with reference to the operation
of FIG. 4 and this sets the bistable circuit B2 to the reset
condition and the next trailing edge of an input clock pulse which
constitutes an interrogate signal, satisfies the gate G3/2 and
therefore sets the bistable B1 permitting step pulses to again
reach the bistable flip-flop JK and the scanning continues.
When an input cycle request signal appears on the line ICR, and the
gate G1/2 is satisfied by the appropriate condition of the bistable
flip-flop JK, with the bistable circuit B1 in the set condition.
The gate G4/2 is therefore satisfied to produce an input cycle on
signal ICO to the input cycle logic described in the foregoing with
reference to FIG. 3. The scanning is interrupted by virtue of
removal of the input from bistable B1 to the gate G5. The operation
continues until the end of the input cycle as determined by the ICF
signal as derived from the input cycle circuit which removes the
input cycle request signal ICR from the cycle access scanner so
that the scanner then reverts to the scanning condition.
Returning now to the interface and the keyboard equipment referred
to previously with reference to FIG. 1, on receiving the "input
cycle on" signal on the line ICO, it will be recalled that the
input cycle is commenced and at the conclusion thereof, the input
cycle finish signal ICF is produced which thereby resets the
bistable CT removing the input cycle request ICR and sets the end
of cycle toggle ECT. Setting of the toggle ECT initiates the "end
of cycle" sequence by energizing the end of cycle relay ECR and
energization of the contact ECR/1 to open state removes
energization of SGR ready for the reception of a new synchronizing
pulse corresponding to the committal of a new parcel to the
conveyor. In addition, the register relay contacts CR1 to CR12 and
DR1 to DR7 are reset thereby in readiness to receive the new input
determined by a further operation of the keyboard. Energization of
the contact ECR2, removal of energization of GR/5 or energization
of CNR/3 gives rise to energization and latching one of ECR until
the cancel function of the logic is completed and the relay GR is
energized. Energization of ECR/3 gives rise to removal of
energization of ECT thus resetting the pick signal to ECR. With the
contact GR/1 as yet unenergized and the keys K1 to K50 unoperated
the relay KRR is energized to prove that all keys are released and
the energized contacts KR/1 together with the de-energized contacts
SGR/2 and the register relays proving that all information is set
at zero, enables the relay GRR to be re-energized as discussed at
the commencement of the earlier description of the operation of the
keyboard.
As mentioned earlier, a cancel button K50 is provided on the
keyboards and this enables the operator to cancel the previous
keyboard operation when he realizes that an error has been made in
operating the keys, always provided that a synchronization signal
has not yet been effective to cause the access scanner to commence
an input cycle. Assuming that a wrong key has been depressed and
that the operator depresses the key K50 this inhibits incorrect
routing. The fact of a key having been operated results in relays
KRR and GR being de-energized and operation of K50 picks cancel
relay CNR which holds over contacts CNR/2 and SR3. Operation of
contact CNR/1 then removes the supply feed to CR1-12 and DR1-7 and
GR picks over KRR1, SGR2 and CR1/2 etc., on the proviso that a
synchronization pulse has not been received. The picking of relay
GR thus releases the cancel relay in readiness for a further code
to be entered by the keyboard.
In some applications it may be desirable that the distance or time
interval between the closing of a gate and the arrival at that gate
of a parcel which is not to be discharged by that gate should be
adjustable independently for each gate without affecting the
corresponding interval between the opening of the gate and the
arrival of a parcel which is to be discharged. This may be simply
achieved by the addition to apparatus shown in the drawings of the
following items:
In FIG. 1 an additional "Count Generator Matrix" with corresponding
additional register relays CR1(a) to CR12(a) and selection gates
G20(a)/1-12. The inputs to the two Count Generator Matrixes are
then derived in parallel from a single keyboard operation.
In FIG. 3 an additional set of gates G9(a)/1-12, such that the
input from interface gates G20/1-12 is now entered via G9/1-12
directly to the core storage device after B4 has been returned to
its reset condition, while the input from interface gates
G20(a)/1-12 is stored in Buffer Store A and entered into the core
storage device via gates G9(a)/1-12 when B4 is in its "set"
condition. It may thus be obtained that the two "count" words used
to determine the opening and closing of one gate may be obtained
from independently adjustable matrixes, in place of the common
adjustable matrix previously described.
In the foregoing description it has been observed that the action
representations recorded in the main storage means occupy storage
addresses which alternate with addresses which carry count
representations. Also, the action representations constitute two
code parts, one to represent the action and the other to identify
the means for performing the action. It is to be understood in this
connection that in certain applications of the invention, the part
constituting a representation of the action pertaining to a
particular count representation may be recorded in the same address
as the respective count representation, representations for
identifying the means to perform the actions being recorded in the
interleaved addresses. In this event, the input and output cycle
logic described with reference to FIGS. 3 and 4, of the drawings
requires modification in respect of the logic, firstly to ensure
recording of the respective parts of the action representations in
the correct addresses and secondly to initiate correct readout from
the respective addresses on the attainment of the requisite
significant decremented count representations.
The above is but one variation of the logic which may be readily
comprehended by the skilled engineer.
It will be appreciated that the specific embodiment of the present
invention as applied to a parcel sorter has been described partly
in terms of logic but since the logical components referred to in
the description are all components of a type which are well known
or readily constructable to persons skilled in the art of
electronic logic employing magnetic storage cores and the like, the
disclosure of the invention will make it readily apparent to
persons skilled in the art in what manner the invention may be
effected.
Whilst moreover the present invention has been described in
specific relation to a parcel sorter, the invention is not intended
to be limited to parcel sorters but to be readily applicable to
other forms of object routing apparatus.
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