Control system and module for an accumulation conveyor

An accumulating conveyor is divided into a plurality of accumulating zones from an infeed end to a discharge end. An accumulation module is associated with each accumulating zone and includes a photo electric sensor, a microprocessor, and input/output connections. Each module is coupled to an actuator that controls the driving of the associated accumulating zone, either engagement or disengagement of the driving force to either move or stop the product thereon. The sensor detects the presence or absence of a product within its zone and communicates the same to the microprocessor. The modules may be set in a singulation mode or a slug mode, the mode determining the throughput of the product within the zone depending on the presence or absence of a product on the upstream and downstream accumulating zone. An enable/disable sleep and jam mode is incorporated into the microprocessor decision process to stop the drive force for the particular zone when no product is forthcoming and to try to dislodge any jammed package from a zone and stop the flow of product upstream thereof. Each accumulation module is in communication with the adjacent accumulation modules both upstream and downstream thereof, where possible, via integral plug-ins to aid in determining whether to move or stop the product depending on the selected modes of operation.

FIELD OF THE INVENTION 
The present invention relates to accumulating conveyors and, more 
particularly, to a control system and associated modules for zero pressure 
accumulating conveyors. 
BACKGROUND OF THE INVENTION 
In the automated conveyor art, one type of automatic conveyor system is 
known as an accumulator conveyor. These types of conveyors are divided 
into a plurality of zones that extend from an inlet end to a discharge 
end. The zones are areas of the conveying surface where driving force to 
move the packages may be applied or removed independently of the other 
zones of the conveyor. These zones provide each package with its own 
stopping place. Packages or items are thus accumulated in successive zones 
for eventual discharge from the conveyor. 
Zero pressure accumulation is a method of accumulating one or more items on 
a conveyor in a manner wherein there is no drive pressure or force trying 
to move the accumulated item before it is ready to be conveyed into 
another zone or discharged from the conveyor. Zero pressure accumulation 
conveyors differ from minimum pressure accumulation conveyors in that with 
minimum pressure conveyors there is always some drive pressure on the 
packages, even when the packages are being accumulated. Generally, each 
zone includes a sensing mechanism to determine whether a package is within 
its zone and associated logic to activate or deactivate the zone's driving 
force. Such sensors may be mechanical, or may be photoelectric. 
However, while there are known electronic sensing systems such as that 
shown and described in U.S. Pat. No. 5,060,785 entitled 
Electrically-Powered Control System For Accumulating Conveyor issued to 
Garrity on Oct. 29, 1991, and U.S. Pat. No. 5,285,887 entitled 
Accumulating Conveyor And Control System issued to Hall on Feb. 15, 1994, 
they are deficient in many respects. Furthermore, these systems are not 
flexible in terms of options, wiring, or the like. 
It is thus an object of the present invention to provide an improved 
control system for an accumulating conveyor. 
It is another object of the present invention to provide a control system 
for an accumulating conveyor that provides photo-electric sensing at 
nearly the same cost as conventional mechanical/pneumatic sensing. 
It is yet another object of the present invention to provide a control 
system for an accumulating conveyor which requires few parts and is simple 
to wire. 
It is further an object of the present invention to provide a control 
system for an accumulating conveyor that has a higher degree of 
reliability than conventional mechanical/pneumatic control systems. 
It is still further an object of the present invention to provide an 
accumulating conveyor control system that has several modes of operation, 
and offers greater flexibility than mechanical and/or pneumatic 
accumulation logic. 
SUMMARY OF THE INVENTION 
The present invention is a control device and/or system for a zero-pressure 
accumulating or accumulation conveyor that provides two modes of operation 
or control of the accumulation conveyor and thus the flow of items 
therealong, namely a singulation mode and a slug mode. The singulation 
mode separates the items while traveling down the conveyor as well as when 
items are released from the stopped conveyor zones to thereby create or 
maintain a zone length gap between the items. The slug mode does not 
separate the items while the items travel down the conveyor either during 
free travel of the conveyor or when items are released from the stopped 
conveyor zones. 
The control device comprises a plurality of accumulation modules located 
along the length of the conveyor, preferably with one module located in 
each accumulating zone. Each accumulation module is generally linked to 
adjacent accumulation modules in a daisy-chain manner via a 
communications/power line. In the case of the first accumulation module of 
the infeed end accumulating zone relative to product flow (the infeed end 
accumulation module), and the last accumulation module of the discharge 
end accumulating zone (discharge end accumulation module), relative to 
product flow, the modules are linked to a single adjacent module, as there 
are no upstream or downstream modules. This allows intercommunication 
between all of the modules. 
Each accumulation module is characterized by a sensor for detecting an item 
within its respective accumulating zone, input/output communications and 
control connections, and logic circuitry coupled to the sensor and 
input/output connections. Additionally, each module is in communication 
with an actuating device that controls the application of the driving 
force for the respective accumulating zone. The logic circuitry receives 
various input signals, when applicable, mainly indicative of 1) product 
detection within its respective accumulating zone of purview, 2) product 
detection within an immediately upstream accumulating zone, and 3) product 
detection within an immediately downstream accumulating zone. Other 
settings or enableable features (inputs) are factors in the evaluation 
process. These various signals are processed or evaluated by the logic 
circuitry of the module to determine whether to stop or continue 
application of the drive force to the accumulating zone of purview of that 
module, and what, if any, output signals to transmit. These evaluations 
are based on whether the control device is set to the singulation or the 
slug mode, as well as any other enabled features described hereinbelow. 
In one form of the present invention, the sensor is a photoelectric type 
sensor and the logic circuitry is a microprocessor, however, other types 
would suffice. The photoelectric sensor provides a signal to the 
microprocessor when an item comes within the sensor zone (a product detect 
signal). This information is typically transmitted to the immediately 
upstream module and the immediately downstream module. The microprocessor 
also receives other input signals that are evaluated along with the sensor 
signal to determine whether to send a signal to apply or maintain the 
drive force to the respective zone, or to deactivate the drive force to 
the respective zone. 
When the control device is set to the singulation mode, in general, 
items/packages separate as they proceed along the accumulation conveyor 
and when the are released therefrom. This mode creates a gap or distance 
between the items along the conveyor as items queue at the discharge end, 
and a zone-length thereafter upon release from the discharge end. When in 
the singulation mode, each accumulation module operates in the following 
manner. When a product is detected within the accumulation module's 
accumulating zone of purview by its sensor, a sensor signal indicative of 
product presence within the zone is received by the logic circuitry of the 
module. The logic circuitry evaluates the signal and causes a product 
detect signal to be transmitted to the immediately upstream accumulating 
module, where applicable, and to an immediately downstream accumulating 
module, where applicable. Thus each accumulating module communicates to 
its neighboring accumulating modules whether a product or package is 
within its respective accumulating zone. 
If a module receives a sensor signal and a product detect signal from an 
immediately downstream module, thus indicating that the downstream 
accumulating zone has a package therein, the logic circuitry sends a no 
drive signal to the associated zone drive actuator to stop the drive force 
to the respective accumulating zone. If the module then detects the 
absence of a package within its accumulating zone, or receives a no 
product detect signal from the immediately downstream module, the logic 
circuitry transmits a drive signal to the associated zone drive actuator 
to cause the zone to drive. 
When the control device is set to the slug mode, the modules operate in 
generally the same manner with the following exceptions. When a product is 
detected with the respective accumulating zone, the product detect signal, 
normally immediately transmitted to the immediately upstream module, is 
delayed for a predetermined time period controlled by the logic circuitry. 
If at any time during the predetermined time period the respective sensor 
does not detect a package the time delay is reset and no product detect 
signal is sent to the upstream module. This allows the free flow of 
packages along the conveyor. This is because a module must receive both a 
sensor signal indicative of product detection within its zone from its own 
sensor, and receive a product detect signal from the immediately 
downstream module in order to cease the drive force for the respective 
accumulating zone. The delay in signal transmission causes the product to 
move down the conveyor without singulation. This can occur when there is a 
gap between the packages or when there are in fact no other arriving 
packages. 
The time delay described above provides a jam protection feature for the 
conveyor. As indicated, if the module detects a package for more than the 
predetermined time period, generally indicating a jam within the 
respective zone, the product detect signal is transmitted to the upstream 
module, while the respective zone continues to drive. This allows the 
upstream modules to accumulate packages until the jam has been removed. 
The jam protection feature may be disabled by setting a jam enable switch 
on the dipswitch to the DISABLE or OFF position. This effectively sets the 
predetermined time period to infinity and no product detect signal will be 
transmitted to the upstream module regardless of whether a package is 
detected for more than the predetermined time period. 
The last module of the control device which is located at the last 
accumulating zone or discharge end zone includes a blanking plug that fits 
over the control connection inputs. The blanking plug generally protects 
the inputs from short circuit and controls the user-selectable modes of 
singulation or slug. The blanking plug includes two (2) terminals that 
provide input connections for selecting slug mode only and 
singulation/slug mode. The default setting is the singulation mode, but is 
overridden by the connections made on the blanking plug. By connecting a 
jumper between the terminals of the blanking plug, the control device is 
set to operate in the slug mode only. By connecting a wire pair to the 
terminals with the other end coupled to a dry contact switch, relay or 
programmable switch device, the control device is set to operate in both 
the singulation mode or the slug mode. When the switch is in the open 
position, the control device operates in the singulation mode. When the 
switch is closed, the control device operates in the slug mode. 
It is also possible to connect two or more conveyors together in an 
end-to-end relationship. An optional conveyor-to-conveyor connector is 
required to link the last accumulation module of the upstream conveyor to 
the first accumulation module of the connecting conveyor. 
According to another aspect of the present invention, each accumulation 
module also has input terminals to accept a zone stop input from an 
outside source, such as a switch or programmable controller. The zone stop 
is in addition to the user-settable modes of operation via the blanking 
plug. Once set, the zone stop input tells the logic circuitry of the 
particular module to stop the drive force for the respective accumulating 
zone once an item is detected within the zone. The zone stop may be used 
at the discharge end to control the discharge of items from the 
accumulating conveyor, or to stop items somewhere along the conveyor path. 
In this mode, the logic circuitry treats the zone stop signal as a product 
detect signal coming from the immediately downstream module indicating 
that a product is present in the immediately downstream accumulating zone. 
When a module receives a zone stop signal and simultaneously receives a 
product detect signal from its own sensor, the logic circuitry does not 
send a product detect signal to the immediately downstream module, as 
normally would occur, in order that the downstream module may "go to 
sleep." 
In accordance with an aspect of the present invention, the logic circuitry 
of each module is set to send a no drive signal to its respective 
actuating device to deactivate the drive force to the respective zone, 
thereby allowing the zone to go to sleep, when certain input signals have 
not been received by the logic circuitry within a predetermined time 
period. The sleep feature may also be manually disabled or enabled by a 
SLEEP DISABLE/SLEEP ENABLE (or OFF/ON) switch on a dipswitch located on 
the module. Generally, the first or infeed accumulation module is set to 
"SLEEP DISABLE" or "OFF." The predetermined time period is, of course, 
arbitrarily defined, and is switchable between two time lengths via 
another switch on the dipswitch. 
When a module does not detect an item within its respective accumulating 
zone, and thus the sensor does not send a product detect signal to the 
logic circuitry, and a product detect signal is not received from the 
immediately upstream module within the predetermined time period, the no 
drive signal is transmitted. Once a product detect signal is received by 
the logic circuitry either from the immediately upstream module or from 
its respective sensor, a drive signal is transmitted to start the zone. If 
however, during the predetermined time period, one of the two product 
detect signals are received, the sleep clock is reset. 
In order to provide power to the modules, a special power plug is connected 
to the control connections of one of the modules such that power may be 
supplied thereto. Up to fifty (50) modules may be powered from a single 
power plug. The communication cable from the downstream module is 
connected to the power plug. 
It should be understood that the term signal may be a positive act such as 
an encoded signal that communicates a desired on or off state, or may be 
the presence or absence of a signal in the case of strict digital signal 
employing an ON/OFF (0/1) protocol. The type of signal is arbitrary 
depending on the overall design of the system as this does not effect the 
concept of the present invention.

DETAILED DESCRIPTION 
Referring now to FIG. 1 there is shown a zero-pressure accumulation 
conveyor generally designated 10 whose upper or conveying surface 12 is 
defined, in this case, by a plurality of rollers 14, although other types 
of conveying surfaces, such as belts, slats, or the like may be used. The 
conveyor 10 is divided into a plurality of accumulating zones identified 
by the letters A, B, C, D, and E, such that there are five (5) 
accumulating zones. Of course, there could be any number of accumulating 
zones depending upon the overall length of the particular conveyor or 
other conveyor design considerations, the number of shown accumulating 
zones five (5), being arbitrary. 
The conveyor 10 has a direction of product flow over the conveying surface 
12, which is arbitrarily chosen as from accumulating zone A towards 
accumulating zone E. Therefore, accumulating zone A is the first 
accumulating zone, generally known as the infeed end accumulating zone, 
while accumulating zone E is the last accumulating zone, generally known 
as the discharge end accumulating zone. As with typical zero-pressure 
accumulating conveyors, each accumulating zone is independently engageable 
and disengageable with a drive force in order to convey packages or items 
through the accumulating zone or to stop the packages or items within the 
accumulating zone. Each accumulating zone may also be separately driven 
with the drive force also being engageable and disengageable. In either 
case, the drive mechanism is selectively applied to the accumulating zones 
according to the receipt of a drive signal to drive the rollers associated 
therewith, while the drive mechanism is disengaged from the accumulating 
zone to disengage the rollers associated therewith according to the 
receipt of a no drive signal as described hereinbelow. This is usually 
accomplished via an actuator in communication with the drive force. 
With reference still to FIG. 1, the rollers are rotatably supported between 
a first siderail 18 and a second siderail 19 which are in turn supported 
by legs 16. Other details of the conveyor structure are not described 
herein as they are well known in the conveyor industry. Disposed 
conveniently on one siderail 19 are a plurality of accumulation modules 
20, designated 20A, 20B, 20C, 20D, and 20E, corresponding to the 
accumulating zones A-E to which each module 20 is associated. In 
communication with each module A-E is a drive force actuator 22A-E each of 
which is able to selectively apply the drive force to each zone or to 
disengage the drive force to each zone depending on the received signal. 
Additionally, each module is in communication with its neighboring or 
adjacent module, both in the upstream direction and the downstream 
direction relative to conveyor flow, where possible, through 
communications cables 42A-E. Accumulating zone A is of course only in 
communication with its adjacent downstream module 20B, while accumulating 
zone E is of course only in communication with its adjacent upstream 
module 20D as would any first and last module. Also, each module 20A-E is 
preferably located proximate the end of each respective zone A-E, relative 
to conveyor flow. The aggregation of accumulation modules 20A-E constitute 
an accumulation control device or system that works in conjunction with 
the drive/no drive actuators and associated couplings to control the flow 
of packages along the conveyor. 
Referring to FIGS. 2 and 3, an accumulation module 20 is shown. It should 
be understood that each accumulation module depicted in the various 
Figures is the same and thus FIGS. 2 and 3, and the following description 
are applicable to all of the modules 20A-E. Each module 20 includes a 
housing or casing 24 that encloses electrical logic circuitry that 
receives various input signals and transmits various output signals based 
on internal evaluations as flow diagrammed via a state diagram (FIG. 4) 
and described hereinbelow with reference thereto. The logic circuitry may 
include a microprocessor and other necessary components, or may be another 
type of logic structure that will perform the functions diagrammed in FIG. 
4 and described herein. The casing 24 has two bores 25, 26 extending 
therethrough for mounting the module 20 to the siderail or other structure 
via screws or the like. A sensor 28 is disposed on one side, the side 
facing the conveying surface 12, the sensor 28 in communication with the 
logic circuitry. The sensor 28 is used to determine the presence or 
absence of an item or package within the respective accumulating zone and 
to send a signal to its respective logic circuitry indicating the same. 
The sensor may be a photoelectric sensor, a proximity sensor, an 
ultrasonic sensor, or any other type of sensor that is capable of 
detecting the presence or absence of an item within the respective 
accumulating zone and providing a signal indicative of the same to the 
logic circuitry. 
The module 20 also has various inputs and outputs generally termed control 
connections for receiving input signals and sending output signals, and 
coupling various devices to the module 20. Signals to and from adjacent 
modules (communications) and power for each module is made via control 
connections 30 including power connections 31 and signal input/output 
connections 32. Integral to the module 20 is a linking 
communications/power cable or line 42, typically between 3-6' in length, 
that terminates in a plug 44. The plug 44 is keyed to match the control 
connections 30, having a power receptacle 45 and a communications 
receptacle 46. By connecting the plug 44 to the control connections of the 
upstream module and so on in a daisy-chain manner, each module is in 
communication with its neighboring modules. 
Additionally, the module 20 has a four (4) switch ON/OFF type dipswitch 34, 
a four (4) pronged terminal block 36, an indicator LED 38, and a 
logo/information area 40. The switches and switch settings for the 
dipswitch 34, as well as the connections to the terminal block 36, will be 
described hereinbelow with reference to the other Figures but form a part 
of the control connections. Different modes of operation of the module 
and/or various time lengths associated with various settings/options may 
be configured via the switches. The LED 38 provides a visual status and 
mode indication coded in blinks of the light to allow perception by a 
remote viewer. 
Referring now to FIG. 7, there is depicted an enlarged view of the front 
face of the module casing 24 showing the LED 38, the dipswitch 34, and the 
terminal block 36. As indicated above, the LED 38 visually provides a real 
time indicator of the status and mode of the particular module according 
to a particular code sequence. The particular code sequence is arbitrary. 
As indicated above, the dipswitch 34 has four (4) two-position switches 
that are used to enable or disable several features or options of the 
present invention and set several parameters therefor. It should be 
understood that the switch choice for the particular function or feature 
is arbitrary. Switch 62 is the solenoid output switch and is used to 
select whether the module's output to the actuator (or solenoid as the 
case may be) that controls the application of the drive force to the 
accumulating zone, is an "ON TO STOP" signal, or an "OFF TO STOP" signal. 
The switch 63 is the jam enable switch and is used to enable or disable 
the jam protection feature for the particular module. This feature is 
available only in the slug mode and helps prevent product pile-up and/or 
damage if a package should become jammed on the conveyor. The default 
setting is in the ENABLE position. Switch 64 is the sleep feature switch. 
It is used to enable or disable the sleep feature for the particular 
module. When the sleep feature is enabled, the logic circuitry of the 
particular module will stop the zone rollers from turning if no packages 
are detected for a set time period through disengagement of the drive 
force. The zone wakes up when a package is detected in the adjacent 
upstream zone or by the current zone. The default setting is ENABLE on all 
modules except for the module on the infeed accumulating zone which is set 
to DISABLE. The last of the four switches, switch 65 is the sleep time 
period selection switch. The switch 65 is used to select the time delay 
period used by the sleep feature before the sleep mode is activated by the 
logic circuitry. Again, the time period is arbitrary, but has been 
selected as five (5) or fifteen (15) seconds. A module must not see a 
package for the time delay period for the module to enter the sleep mode. 
The terminal block 36 has four (4) terminals that clamp wire using a simple 
lever action and is used to couple devices to the module. The wires are 
initially stripped before insertion into the terminal. Terminals 66, 67 
are used to couple the actuator or solenoid that controls the application 
of the drive force to the particular accumulating zone to the module for 
control thereof. Terminals 68, 69 are used to accept a zone stop signal 
from a "dry contact" type switch, PLC (Programmable Logic Controller), 
etc., in order to allow any zone to become a stop zone through use of the 
connected switch. Closing the switch will place the module into the 
accumulate mode such that the next package to activate the module 
(detected by the sensor) will be stopped within the zone and held until 
the switch is open. The zone stop feature is logically used by the 
discharge module to control the release of packages from the discharge 
zone. By coupling a switch to the terminals 68, 69, any zone may become a 
stop zone. 
Referring to FIG. 5 there is depicted an enlarged, partial view of the 
siderail 19 of the present conveyor 10 with the control device installed 
thereon. As indicated, there is one module 20 for each accumulating zone 
A-E, and thus the modules associated with the particular zones are labeled 
20A-20E, with the respective components likewise distinguished by the A-E 
designation. Initially, the modules 20A-E are mounted on the siderail via 
the mounting bores 25,26, such that the sensors 28A-E may "view" the other 
siderail 18. Disposed on the other siderail 18 is a reflector device (not 
shown) for sending the sensor beam back to the sensor pickup. Generally, 
the sensor 28 includes both a transmitter and a receiver, either as an 
integral whole or as separate components. Each module is coupled to its 
immediately adjacent upstream module via the link 48 by inserting the plug 
44 of its link 48 into the control connection 30 of the adjacent upstream 
module. An actuator, or solenoid, 22 is associated with each accumulating 
zone A-E as are modules 20. Each module 20A-E is in communication with a 
respective actuator 22A-E by respective lines 48A-E which are coupled to 
the respective terminals 66A-E, 67A-E of the respective terminal blocks 
36A-E. The actuators 22A-E are in communication via respective lines 50A-E 
to engage or disengage the drive force (not shown) for the particular 
accumulating zone A-E. In this depiction, the actuators 22A-E are 
pneumatic and thus respective air couplings 52A-E are coupled to an air 
infeed line 124. The particulars of air actuated solenoids (actuators) and 
associated devices to engage and disengage the drive force are well known 
in the art. Also, other types of systems, such as mechanical or a 
pneumatic/mechanical combination may be utilized in accordance with the 
principles of the present invention. 
It should be noticed that the infeed zone A module 20A is not coupled to an 
upstream module because there is none. However, the module 20A is in 
communication with module 20B. It should also be noticed that the 
discharge zone E module 20E has an optional blanking plug 54 inserted over 
the control connections rather than a plug 44 as there is no downstream 
module. The blanking plug help to prevent short circuits between the 
control connections, and provides mode selection for the entire control 
device. The default mode is the singulation mode, but if the user desires 
to use the slug mode or switch between the singulation and slug mode, the 
blanking plug 54 needs to be used. With additional reference to FIGS. 8A, 
8B an enlarged blanking plug is depicted. The blanking plug 54 has two (2) 
terminals 55,56, to which stripped wires may be attached. In FIG. 8A, a 
jumper 58 is used to tie the terminals 55,56 together. This results in the 
control device being set in the slug mode only. In FIG. 8B, a twisted pair 
wire 60 is coupled at one end to the terminals 55,56 and to the other end 
to any type of dry contact switch, relay, PLC, or the like 126. In this 
configuration, the mode of operation is selectable between the singulation 
mode and the slug mode depending on the state of the switch. When the 
switch 126 is open, the conveyor 10 will be in the singulation mode. When 
the switch 126 is closed, the conveyor 10 will be in the slug mode. FIG. 5 
also shows a switch 128 (that could be a relay, PLC or the like) coupled 
to the terminal block 36E (in particular terminals 68E and 69E) via wire 
129 to control the discharge of the products through the stop zone 
connections. Thus, when the switch 128 is closed, and a package is 
detected within the module's accumulating zone purview, the zone will stop 
until the package is no longer detected, or the zone stop switch is 
released. A reference should be made to the below state diagram and 
description of operation for the modules. 
Referring now to FIG. 6, there is depicted an accumulation module 20 having 
a power plug 122 installed on the control connections. A power plug 122 is 
necessary in order to couple a power supply (not shown) to operate the 
modules. A power line (not shown) is connected to the "+" and "-" 
terminals while the adjacent downstream module plug 44 is attached to the 
power plug 122. A single power source can power up to approximately fifty 
(50) modules, twenty-five (25) on either side of the powered module. 
The logic circuitry flow or evaluation of the various inputs and the 
required outputs of each module 20 is depicted as a state diagram in FIG. 
4 and attention is now directed thereto. Any type of logic circuitry that 
will accomplish the state diagram may be utilized by each module. 
Initially, it should be understood that 1) there is one module for each 
accumulating zone and thus, any reference to a module and "its" 
accumulating zone is assumed to mean the accumulating zone under the 
purview of the referenced module; and 2) any reference to "a signal" or 
"no signal" is any form of communication that accomplishes the intended 
purpose. Essentially, these are three (3) STATES, the ZONE RUNNING STATE 
80, the ZONE SLEEPING STATE 92, and the ZONE STOPPED STATE 100. Each 
"step" along the way is a logical question whose answer must be "true" to 
proceed therealong to the next STATE in accordance with the general 
principles of STATE diagrams. The main or normal state of each module is 
the ZONE RUNNING STATE 80. When power is applied to the conveyor and the 
control device, each module transmits a drive signal to its respective 
actuator, which in turn enables the drive force for the respective 
accumulating zone, and thus ZONE RUNNING STATE 80. Next, the logic 
circuitry checks its sensor to determine whether a package or item has 
been detected within the respective accumulating zone. Such checking by 
the logic circuitry may take the form of polling, of received signal(s) 
from the sensor, or of non receipt of signal(s) from the sensor. 
The next few paragraphs describe the sleep mode feature of the present 
invention. If no packages are detected by the sensor and thus the current 
accumulating zone is empty, the CURRENT ZONE EMPTY flow path is correct, 
the logic circuitry flow proceeds along the flow path to the query 
DOWNSTREAM OUTPUT OFF 82. In response to the CURRENT ZONE EMPTY, at the 
DOWNSTREAM OUTPUT OFF 82, the logic circuitry transmits a no product 
detect signal (or e.g., stops sending a product detect signal) to the 
downstream accumulating module. Next, the logic circuitry proceeds to the 
UPSTREAM OUTPUT OFF 84 and a no product detect signal is transmitted to 
the upstream accumulating module. 
Next, the logic circuitry proceeds to the CHECK SLEEP ENABLE 86 where the 
position of the dipswitch switch 64 is checked to see if the SLEEP MODE 
function is enabled or disabled. If the SLEEP MODE is enabled, the logic 
circuitry proceeds to the CHECK STATUS UPSTREAM 88 to see if a package has 
been detected within the immediately upstream accumulating zone. If a 
package has been detected in the immediately upstream accumulating zone, 
then the immediately upstream accumulation module will accordingly 
transmit a product detect signal to its immediately downstream 
accumulation module, and an UPSTREAM INPUT RECEIVED answer maintains the 
accumulation zone running. If however, an UPSTREAM INPUT NOT RECEIVED is 
the answer to the CHECK STATUS UPSTREAM 88, the logic circuitry proceeds 
to the START SLEEP TIMER 90 and the sleep timer starts. The timer period 
is a predetermined time length, that is arbitrarily chosen as five (5) 
seconds or fifteen (15) seconds settable via dipswitch 65. If a product 
detect signal is received from the immediately upstream module, then the 
logic circuitry transmits a drive signal to the actuator to start the zone 
running, STATE 80. If however, the TIMER EXPIRES, the module transmits a 
no drive signal and the zone enters the ZONE SLEEPING STATE 92 whereupon 
the drive force is disengaged from the accumulating zone and the zone 
sleeps. Again, the logic circuitry checks to determine whether a product 
detect signal has been received from the immediately upstream module and, 
if it has, the zone is set to running by the transmission of a drive 
signal to the respective actuator to engage the drive force. The 
accumulating zone remains in the sleep mode until either 1) a product 
detect signal is received from the upstream accumulation module 
(indicating a package within the immediately upstream accumulating zone) 
or 2) the current accumulating zone becomes occupied by a package. If the 
latter is the case, the logic circuitry continues its logic flow to the 
CHECK STATUS DOWNSTREAM 94 which will be described in conjunction with the 
ZONE RUNNING STATE 80. During the above described flow at the CHECK SLEEP 
ENABLE 86 and, if the sleep feature has been disabled through dipswitch 
64, the flow brings the logic circuitry back to the ZONE RUNNING STATE 80. 
While the module is in the ZONE RUNNING STATE 80, if the respective sensor 
is detecting a package within its accumulating zone, then the current zone 
is occupied and the logic circuitry proceeds to the CHECK STATUS 
DOWNSTREAM 94. If a product detect signal is being received from the 
immediately downstream module then the downstream accumulating zone is 
occupied. At this point, the current module is both detecting a package 
within its zone and receiving a product detect signal from the immediately 
downstream module. The current module then transmits a product detect 
signal to the downstream module, the DOWNSTREAM OUTPUT ON 96 and transmits 
a product detect signal to the upstream module, the UPSTREAM OUTPUT ON 98. 
Thereafter, the accumulating zone is stopped, ZONE STOPPED STATE 100, by 
the logic circuitry transmitting a no drive signal to the respective 
actuator to disable the drive force to the particular accumulating zone. 
At this point, two 2 events may occur. First, if the zone stop is 
inactive, and if at this point a product detect signal from the adjacent 
downstream module is not received by the logic circuitry of the current 
module, the module returns to the ZONE RUNNING STATE 80. Second, if the 
current zone becomes empty, the logic circuitry ceases its product detect 
signal to the adjacent upstream module, the UPSTREAM OUTPUT OFF 102, 
ceases its product detect signal to the adjacent downstream module, the 
DOWNSTREAM OUTPUT OFF 104, and proceeds to the ZONE RUNNING STATE 80. 
The above paragraph detailed the module logic circuitry flow path with 
respect to a product being detected within the current accumulating zone 
and the receipt of a product detect signal from the adjacent downstream 
module. Now, the module logic circuitry flow path will be described 
starting at the CHECK STATUS DOWNSTREAM 94. If the current module is not 
receiving a product detect signal from the adjacent downstream module, 
indicating that the adjacent downstream zone is not occupied by a package, 
the flow proceeds to the CHECK ZONE STOP 106. If the zone stop feature is 
enabled (active), then the logic circuitry transmits a product detect 
signal to the adjacent upstream module, the UPSTREAM OUTPUT ON 98, and the 
program flows as described above. If however, the zone stop is disabled 
(inactive) the program flow proceeds to the DOWNSTREAM OUTPUT ON 108 where 
the logic circuitry transmits a product detect signal to the adjacent 
downstream module. Then the logic circuitry checks the mode of operation 
of the module by checking to see if the slug mode has been enabled, the 
CHECK SLUG STATUS 110, since the singulation mode is the default mode. If 
the slug mode has not been chosen, and thus inactive, the module transmits 
a product detect signal to the adjacent upstream module, the UPSTREAM 
OUTPUT ON 116, and thereafter returns to the ZONE RUNNING STATE 80. This 
means that a product has been detected within the current accumulating 
zone, the singulation mode has been chosen, but since no package has been 
detected in the adjacent downstream accumulating zone, the package will 
proceed down the conveyor. 
If however, from the CHECK SLUG STATUS 110, the module is set to the slug 
mode, the slug status is active and the logic circuitry proceeds to the 
CHECK JAM PROTECTION 112 to ascertain whether the jam protection feature 
has been enabled or disabled. If the jam protection feature has been 
disabled, the logic circuitry proceeds to the ZONE RUNNING STATE 80. If 
the jam protection feature is enabled or active, the logic circuitry 
proceeds to the START JAM TIMER 114, whereupon if the timer expires, the 
logic circuitry transmits a product detect signal to the adjacent upstream 
module, the UPSTREAM OUTPUT ON 116. This is because if a module detects 
the presence of a package within its zone for more than the timer period, 
it is assumed that the package is jammed on the conveyor. By sending a 
product detect signal to the adjacent upstream module, the upstream zones 
begin to accumulate packages until the jam is cleared. 
It is evident that all modules cooperate to handle packages by receiving 
and sending various signals to each other and evaluating the same in 
accordance with the STATE diagram. 
Operation 
With reference now to FIGS. 9-17, the overall operation of the present 
accumulating conveyor control device will be described relative to 
packages entering the accumulating conveyor, being carried down the 
conveyor, and being discharged from the conveyor, when the control device 
is in the singulation mode, the slug mode, and the various features 
associated therewith. It should initially be understood that, 1) in FIGS. 
9-12, the sequence of events are applicable to both the singulation mode 
and the slug mode; 2) in FIGS. 13 and 14, the sequence of events apply to 
the singulation mode only; 3) in FIGS. 15 and 16, the sequence of events 
are applicable to the slug mode only; and 4) in FIG. 17, the sequence of 
events applies to both the singulation and slug modes. 
FIG. 9 depicts an empty accumulating conveyor 10 having five (5) zones A-E 
with zone A at the infeed end 118 and zone E at the discharge end 120. The 
conveyor has no packages thereon and is thus empty. Zones B-E are sleeping 
(not running) assuming the sleep mode is enabled, indicating that there 
has not been any package for the set time period. Zone A however, is set 
to sleep mode disabled such that zone A is running in order to convey a 
package to the discharge zone E and begin the "waking up" process. Zone E 
has its zone stop setting to active to cause the first carton to reach 
zone E to be stopped therein. In FIG. 10, a package P1has entered zone A. 
Upon detection of the package P1in zone A by the module 20A, a product 
detect signal is sent to the adjacent downstream module 20B. Upon receipt 
of a product detect signal from the adjacent upstream module 20A, module 
20B transmits a drive signal to its respective actuator to "wake up" the 
zone. Thus, the package P1is transported from zone A into zone B. 
Referring to FIG. 11, the package P1has been transported all the way to 
zone E, the discharge zone. Each adjacent module from module 20B, 
therefore modules 20C and 20D have run through the same sequence as 
described between modules 20A and 20B. However, when the package P1reaches 
zone E, module 20E being set to zone stop enable, transmits a no drive 
signal to its respective actuator to stop the drive force in zone E. The 
module 20E simultaneously sends a product detect signal to the adjacent 
upstream module 20D. Zones D and C are still in the zone running state as 
their sleep timers will not yet have expired, while zone B is in the sleep 
mode as its sleep timer will have expired. We will assume that it is not 
desired to discharge package P1from the conveyor 10 at the present. FIG. 
12 depicts the situation where two more packages P2, P3have entered the 
conveyor 10. Package P2travels down the conveyor as described above until 
it detected by module 20D. Since module 20D has already received a product 
detect signal from the adjacent downstream module 20E, the detection of 
the package P2within its zone, zone D, will cause the module to transmit a 
no drive signal to stop its zone, zone D. Module 20D also sends a product 
detect signal to its adjacent upstream module 20C, and to its adjacent 
downstream module 20E. As package P3travels down the conveyor 10 it is 
detected by module 20C. Since module 20C has already received a product 
detect signal from the adjacent downstream module 20D, the module 20C 
outputs a no drive signal to stop the zone, zone C. Module 20C also 
transmits a product detect signal to the adjacent upstream module 20B and 
to the adjacent downstream module 20D. Also, since no packages have 
entered the conveyor 10, zone B has gone to sleep. 
Again, the sequence of events described above with reference to FIGS. 9-12 
are applicable to both the singulation mode and the slug mode. If the zone 
E module 20E were not set to zone stop, the products would be discharged 
from the conveyor regardless of the mode, unless the products were too 
close together while in the singulation mode. In the singulation mode, the 
packages would momentarily stop within the zones to provide the proper 
spacing. 
Referring to FIGS. 13 and 14, the discharge of packages from the conveyor 
will be described when the control device is set to the singulation mode. 
When it is desired to discharge the packages from the conveyor, the zone 
stop input to module 20E is disabled or set to inactive. This will cause 
the module 20E to send a drive signal to start the respective zone running 
since the module 20E will not be receiving a product detect signal from an 
adjacent downstream module in addition to the current product detect 
signal from its own sensor, because there is no downstream module. As the 
package travels along zone E, the module 20E will continue to send a 
product detect signal to the adjacent upstream module 20D until the entire 
package has cleared the module 20E. Since module 20D is still receiving 
its own product detect signal and a downstream product detect signal, zone 
D remain stopped. This produces a gap between the packages approximately 
equal in length to the length of the zones, hence the term singulation. 
Once however, the package P1has cleared the module 20E, the module 20E 
stops sending a product detect signal to the adjacent upstream module 20D 
causing the module 20D to send a drive signal to start the drive force for 
its zone, zone D. The package P2continues to advance through zone D while 
zone C is still stopped since the zone D module 20D is still detecting a 
package. As the package P2clears the module 20D, the product detect signal 
to the adjacent upstream module 20C ceases allowing the package P3to begin 
its travel down the conveyor. The package P2is discharged from the 
conveyor as explained above with reference to package P1, likewise with 
package P3. 
FIG. 15 depicts the release of packages after accumulation in FIG. 12 when 
the conveyor is in the slug mode. The zone stop input to module 20E has 
been set to inactive causing module 20E to change zone E to a running 
state, in turn causing zone E to begin discharge of package P1. In 
contrast to the singulation sequence, module 20E will not immediately send 
a product detect signal to the adjacent upstream module 20D even though a 
package P1is still being detected by the module 20E, but instead starts 
the jam timer. If package P1is still being detected by module 20E after 
the jam timer has expired, the product detect signal is then sent to the 
adjacent upstream module 20D. Typically, the package P1will have been 
discharged from the conveyor and thus will have traveled past the module 
20E before the expiration of the jam timer, and thus the product detect 
signal is never sent to the adjacent upstream module 20D. At this point, 
since module 20D is no longer receiving a product detect signal from the 
adjacent downstream module 20E, zone D becomes active through the module 
20D outputting a drive signal, thus advancing package P2. This process 
continues upstream until the packages have been discharged from the 
conveyor. This sequence of events happens so quickly that for practical 
purposes the zones change from the stopped state to the running state 
simultaneously. 
In FIG. 16, the jam protection feature is demonstrated as it applies to the 
slug mode. Package P1is shown as being jammed between zones C and D, and 
is being detected by module 20C. Upon detection of package P1, module 20C 
begins the jam timer (in addition to sending a product detect signal to 
the adjacent downstream module 20D). Since the package P1is jammed, the 
timer will expire (time out) thus, causing the module 20C to send a 
product detect signal to the adjacent upstream module 20B. While the jam 
timer for module 20C was operating, packages P2and P3were driven into the 
jammed package P1. When module 20B receives the product detect signal from 
the adjacent downstream module 20C, it will generate a no drive signal to 
stop the zone, zone B. Module 20B which is detecting package P3also sends 
a product detect signal to the adjacent upstream module 20A, bypassing the 
jam timer in module 20B. When the package P4then is detected by the module 
20A, a no drive signal is generated by the module 20A to stop the zone A 
from running. Once the jammed package P1is dislodged or removed, the 
conveyor returns to the normal slug mode state. 
Again, with the jam protection enabled while in the slug mode, if a package 
becomes jammed at any zone for a predetermined time period (e.g. 6 
seconds) or longer, packages on the upstream side of the jammed package 
will stop in sequence until the jammed package is dislodged or removed. 
The zone containing the jammed package will continue to drive, in many 
cases dislodging the jammed package without outside help. The zones will 
return to normal operating mode once the jam is cleared. 
Finally, with reference to FIG. 17, the use of a stop zone wired in the 
middle of the conveyor is illustrated. In this instance a switch has been 
connected to the appropriate terminals of the terminal block of module 20C 
in order to make module 20C a zone stop. By setting the zone stop input of 
module 20C to active, module 20C is set up to stop the package P1when it 
enters zone C. Packages P2and P3in stop in zones B and A in accordance 
with the sequence described with reference to FIG. 12. 
While the foregoing is directed to the preferred embodiment of the present 
invention, other and further embodiments of the invention may be devised 
without departing from the basic scope thereof, and the scope thereof is 
determined by the claims which follow.