Description and Related Art There are a number of conveyor control systems that have been disclosed that enable a conveyor system to switch between transportation modes and accumulation modes. An example of this type of control system is shown in U. S. Patent No.

5,191,967 (Woltjer). In the control system shown in Figure 6 of Woltjer, a sensor will either activate the drive means for all upstream controlled zones or deactivate the drive means for the upstream adjacent zone. Thus, a zone will either be in the transportation mode or the accumulation mode.

U. S. Patent No. 5,358,097 (Bakkila) is a continuation in part of the above- patented patent application that issued as Woltjer. Bakkila shows grouping the small zones controlled by a single sensor into larger zones. As shown in Figure 5 of Bakkila, the last or guardian sensor 56 will override the interdependent sensors 54.

Thus, when sensor 56 does not detect a package, then all upstream interdependent sensors 54 will be overridden and the associated drive means engaged so that zone 52 would be in the transportation mode. If sensor 56 detects a package, then the adjacent upstream sensor 54 will be active. Other interdependent sensors 54 are active when all sensors 54 or 56 downstream are detecting a package. Thus, only one sensor 54 or

56 in a given zone 52 will control the operation of the zone 52 at a given time.

Therefore, zone 52 can not operate in a singulation mode while accumulating packages. Therefore, this conveyor also only switches between transportation and accumulation modes.

The lack of a transition or decelearation section in a conveyor results in packages on the transportation section of the conveyor impacting packages on the accumulation section. These impacts have the potential to cause damage to the packing material as well as the contents of the packages.

SUMMARY OF THE INVENTION Accordingly, there remains a need for an accumulation conveyor that can be controlled to automatically provide one or more singulation zones between the zones in transportation mode and the zones in accumulation mode of the conveyor. When a conveyor zone is in the transportation mode, packages in the zone are constantly moving. In contrast, a conveyor zone in the accumulation mode does not power the conveyor rolls and thus, permits the packages to accumulate on the conveyor in the zones in the accumulation mode. A conveyor zone in the singulation mode would only provide power to the conveyor rolls in the zone to move the package when there is an absence of packages detected in a selected downstream zone. Thus, a singulation zone (s), when located between the portion of the conveyor in the transportation mode and the portion of the conveyor in the accumulation mode, would provide a transition or deceleration area for a package to reduce the risk of damage to each package or its contents.

The present invention has solved the problems cited above and generally comprises a control system for a conveyor that will automatically shift zones of the conveyor between transportation, singulation, and accumulation modes. This control system accomplishes this automatic shifting by using individual control zones and unified control zones.

Initially, the conveyor is segmented into individual control zones. An individual control zone has an individual sensor that provides a signal or output to the individual control. The output from the individual control will activate/deactivate the driving means for the conveyor rolls in either the individual control zone, an adjacent individual control zone, or another individual control zone of the conveyer. When the individual sensor detects a package on the conveyor, the individual control, unless overridden, will cause the driving means for the individual zone controlled by the individual sensor to be deactivated. If the individual sensor does not detect a package, then the individual control will activate the driving means for the conveyor rolls in the individual zone controlled by the associated individual sensor. Thus, the individual control will permit it's associated individual zone to operate in a singulation mode until a package stops in a location on the conveyor where the package will be constantly detected. Therefore, the individual control may switch the conveyor between singulation mode and accumulation mode.

The conveyor is also segmented into unified control zones. A unified control zone may have any number of individual control zones. Typically, the unified control zone will have between approximately four and approximately six individual control zones. For each unified control zone there is at least one unified sensor that provides a signal or output to a unified control. The output of the unified control located in a particular unified zone can override the individual controls associated with either the unified control zone, an adjacent unified control zone, or another unified control zone of the conveyer so that the associated unified control zone may be switched between transportation and singulation modes.

For one embodiment of the present invention, if a selected unified zone (typically the adjacent downstream unified zone) is not in the transportation mode, then when the unified sensor associated with a particular unified zone detects a package, the unified control will remove the override signal from the individual controls associated with the unified zone and permit each individual zone within the unified zone to return to singulation mode. If the unified sensor that controls a particular unified zone does not detect a package, then the unified control will

override the individual controls in that unified zone causing the unified zone to operate in the transportation mode until the unified sensor for the particular unified zone detects a package. However, if a selected unified zone (typically the adjacent downstream unified zone) is in the transportation mode, then the unified sensor that controls the present unified zone may be overridden so that when the unified sensor associated with a particular unified zone detects a package, the unified control may provide an override signal to the individual controls associated with the unified zone and each individual zone within the unified zone will remain in the transportation mode. Additionally, if the unified sensor that controls a particular unified zone does not detect a package, then the unified control (which itself may be overridden) may continue to override the individual controls in that unified zone causing the unified zone to operate in the transportation mode until the unified sensor for the particular unified zone detects a package.

The unified sensor may be a selected individual sensor together with the individual control associated with the individual sensor that provides an output to the unified control.

An object of the invention is to provide a control system for a conveyor that can automatically switch zones of the conveyor between transportation, singulation, and accumulation modes. The singulation zone (s) serving as a transition or deceleration zone that reduces the risk of damage to the packaging and contents of a package.

Another object of the invention is to provide a control system that may permit the singulation discharge of the conveyor. The singulation spacing is established once and thereafter the product is moved in the transport mode.

Yet another object of the invention is to provide a control system that may permit the auto-slug discharge of the conveyor. Auto-slug discharge is the discharge of each unified zone of the conveyor as a slug with a small gap/space (approximately 1 individual zone long) between slugs. Thus, in essence, this mode of discharge

would permit the unified zones to act similar to individual zones in singulation discharge.

Yet another object of the invention is to provide a control system that may permit the slug discharge of the conveyor. Slug discharge is the discharge of the conveyor as a slug.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention. In the drawings: Figure 1 is a diagrammatic representation of three individual zones of the conveyor using the control system in accordance with the present invention.

Figure 2 is a diagrammatic representation of a unified control zone formed from a series of individual control zones shown in Figure 1.

Figure 3a is a diagrammatic representation of a conveyor using a series of unified control zones shown in Figure 2.

Figure 3b is a diagrammatic representation of the entire conveyor, divided longitudinally into a transport area, a singulation area and an accumulation area in accordance with the present invention.

Figure 4 illustrates three individual control zones and the controls for the driving means for the conveyor rolls of each individual zone shown in Figure 1.

Figure 5 illustrates a process control flow chart for the individual control zones shown in Figure 4.

Figure 6a illustrates a unified control zone of the type shown in Figure 2, provided with one unified sensor that provides an input to the control means that controls the upstream unified control zone.

Figure 6b illustrates a unified control zone of the type shown in Figure 2, provided with two unified sensors that provide an input to the control means that controls the upstream unified control zone.

Figure 6c illustrates a unified control zone of the type shown in Figure 2, provided with two unified sensors that provide an input to the control means that controls the upstream unified control zone and a singulation sensor that provides an input to a singulation control means.

Figure 7a illustrates a process control flow chart for the unified control zone shown in Figure 6a.

Figure 7b illustrates a process control flow chart for the two sensor unified control zone shown in Figure 6b.

Figure 7c illustrates a process control flow chart for the singulation discharge control zone shown in Figure 6c.

Figure 8 is a diagrammatic representation of a unified control zone of the type shown in Figure 2, made up of four individual zones and provided with a Sensor Down control to maintain all of the sensor rolls of the unified zone in a position just below the conveyor rolls.

Reference will now be made in detail to the present preferred embodiment of the invention, examples of which are illustrated in the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Overview: The conveyor control system of the present invention is generally installed on a conveyor of conventional construction. The conveyor comprises a plurality of conveyor rolls provided with appropriate bearings and supported by a pair of parallel side frames (not shown). The side frames are joined together by appropriate brace members to maintain their parallelism. In most instances, the side frames are provided with legs to maintain the conveyor rolls at a pre-determined height above the floor supporting the conveyor.

Figure 1 diagrammatically illustrates a portion of the conveyor controlled by the control system of the present invention. The conveyor is generally indicated at 1 and is provided with live or driven conveyor rolls 2. The conveyor rolls 2 are divided into individual zones Za. Figure 1 illustrates three such zones Zal, Za2, and Za3.

Generally, the individual zones will be made up of equal numbers of conveyor rolls 2.

While any number of conveyor rolls per zone can be used, the individual zone Za of Figure 1 is shown as having eight conveyor rolls 2.

Figure 2 is a diagrammatic representation of a series of individual zones Zal, Za2, Za3, and Za4 which, together, constitute a unified zone Zb. Unified zone Zb may comprise any number of individual zones Za. Preferably, a unified zone Zb will have between four and six individual zones Za.

Figure 3a is a diagrammatic representation of the overall conveyor 1 comprising a plurality of unified zones Zb.

Reference is now made to Figure 3b, which illustrates the entire conveyor 1.

It will be assumed that the left end of the conveyor is the receiving end and the right end of the conveyor is the discharging end.

In Figure 3b, conveyor 1 is divided into three mode zones: a transport zone T, a singulation zone S and an accumulation zone A. The interface between the

transport zone A and the singulation zone S is indicated by broken line X. The interface between singulation zone S and accumulation zone A is indicated by broken line Y.

Each of the transport, singulation and accumulations zones may be made up of a plurality of unified zones.

The three mode zones perform different functions. The accumulation mode zone A provides for the collection of packages; the transportation mode zone T provides for the continuous transportation of packages ; and the singulation mode zone S, serves as a buffer, transition, or deceleration section between the accumulation and transportation mode zones. The control system of the present invention provides for the physical location of these mode zones to move along the conveyor 1 as the unified zones automatically shift between the transportation and singulation modes and as individual zones shift between singulation and accumulation modes. Thus, the size of the transportation and accumulation mode zones will automatically change in response to the number of packages in the accumulation section.

An interesting characteristic of the conveyor of the present invention lies in the fact that it is automatically self-adjusting. For example, as more cartons accumulate in the accumulation mode zone, adjacent parts of the singulation mode zone will be added to the accumulation mode zone and the interface Y will shift to the left as viewed in Figure 3b. At the same time, one or more of the unified zones Zb of the transport mode zone will be added to the singulation mode zone, shifting interface line X to the left as viewed in Figure 3b. As a result, when the accumulation mode zone grows, the transport mode zone diminishes. The opposite occurs when packages in the accumulation mode zone are removed from the accumulation mode zone at a rate greater than those added to the accumulation mode zone.

The size of the singulation mode zone S is set by the control system.

Typically, the control system would be hard wired for electrical control systems or "hard piped/tubed"for pneumatic systems. However, if a programmable control

system is utilized, then the size of the singulation mode zone S could be altered by the operator.

As used herein and in the claims, the term"package"means any package, object, or product that is carried by the conveyor.

Individual Control Zone: With reference now to Figure 4, each individual control zone Za has an individual sensor 4, an individual control means 70, and actuating means generally indicated at 72. Additionally, within this control zone there are standard conveyor rolls or live rolls 2 and drive means 3. Sensor 4 provides a signal or output to the individual control means 70. Depending on the output or signal received by control means 70, control means 70 will activate or deactivate actuating means 72. In the embodiment shown in Figure 4, the sensor 4 and control means 70 located in a particular individual zone Za (n) will activate or deactivate all the actuating means 72 for the next adjacent upstream zone Za (n-l). The sensor 4 and control means 70, however, may be located anywhere desired on conveyor 1. When actuating means 72 is activated, drive means 3 will engage and/or rotate live rolls 2. Typically, when individual sensor 4 detects the absence of a package, individual control 70 will activate, actuating means 72. This process is shown in individual zone flow chart 100, shown in Figure 5. The individual flow chart provides a flow chart for the control process used in individual control zone Za and discussed above.

Prior art workers have devised a number of well-known drive means 3 for live rolls 2. For example, a continuous belt or chain may be shifted into and out of contact with conveyor rolls 2. When the belt or chain contacts conveyor rolls 2 it will rotate conveyor rolls 2 in the conveying direction. When the belt or chain is shifted out of contact with conveyor rolls 2, the conveyor rolls 2 begin free wheeling. It is within the scope of the invention to provide each roll with its own electric motor or other appropriate drive means. For purposes of an exemplary showing, Figure 4 illustrates three zones Zal, Za2 and Za3, each having conveyor rolls 2 and a driven roll 6 for

each adjacent pair of conveyor rolls 2. Each driven roll 6 is activated/deactivated (i. e., shifted into and out of contact with its respective pair of conveyor rolls) by a pneumatic bellows-type lifting device 7, as is known in the art. Thus, driving means 3 may be any device or method for supplying rotary power to conveyor rolls 2.

Individual sensor 4 may be any device that can detect the presence of a package on the conveyor 1 proximate the sensor 4. For example, individual sensor 4 may be an electrical switch that would close or open an electrical circuit when a package passed over the switch, and pushed the switch mechanism in a downward direction.

Alternatively, a photo cell or light detector and a light source could be used as a sensor to detect the presence of a package on the conveyor 1 between the light source and the photo cell or light detector. The preferred light source would be a directed light source like a laser. An LED laser may have sufficient power to be utilized in some applications. Preferably, the light detector would be optimized (most sensitive) at the wavelength of the light transmitted by the light source.

Similarly, low power microwave or other electromagnetic transmitters and receivers could be employed. The frequency and/or wavelength, and power level at the transmitter would be determined by the material properties of the expected packages to be transported by the conveyor. Preferably the transmitted signal would be blocked or have a significant decrease in signal intensity at the receiver when a package on the conveyor 1 passed between the transmitter and the receiver. Any signal frequency or power may be used, so long as the receiver is capable of differentiating between the signal received when an object is between the transmitter and the receiver and when there is a clear path between the transmitter and receiver.

Preferably, individual sensor 4 comprises a sensor roll 8 rotatively mounted on a shaft (not shown). The shaft extends between and is affixed to a pair of rocking arms 9. Arm 9 is pivoted to the adjacent conveyor side (not shown) at pivot 10.

Similarly, the other rocking arm 9 of the pair (not shown) is pivoted to the other

conveyor side (not shown). The sensor roll 8 is maintained slightly above conveyor rolls 2 by counter balance means, spring means or the like, as is well known in the art.

Individual sensor 4 can be located anywhere along the conveyor 1 where it is desired to detect a package on the conveyor 1 for the purpose of controlling the operation of the live rolls 2 in a particular individual zone Za. Typically, the individual sensor 4 located in a particular individual zone Za (n) will control the adjacent upstream individual zone Za (n-1). Thus, the sensor 4 provides the input for control means 70 that controls the activation/deactivation of driving means 3 for the adjacent upstream zone Za.

Individual control means 70 can be any device compatible with the output or signal provided by the individual sensor 4 selected. Additionally, individual control means 70 must have an output or signal that can operate or is compatible with the actuating means 72 selected. For example, control means 70 may be an electronic switch, a logic circuit, solenoid-operated valve, or other device. Preferably, control means 70 is a sensor valve 5 that is actuated by the lowermost end of rocking arm 9.

This sensor valve 5 will be open when the sensor roll 8 is positioned above conveyor roll 2. When the sensor roll 8 is depressed by a package moving over conveyor rolls 2, the lower end of the rocking arm 9 will move away from sensor valve 5 and the sensor valve 5 will shift to a closed position. The sensor valves of Figure 4 are shown at 5a, 5b and 5c.

Alternatively, if drive means 3 is an electric motor and sensor 4 is the sensor roll 8 and rocker arm 9 (discussed above), this sensor 4 could open/close a switch or contacts that would cause a switch to operate whereby electric power could be provided/secured to the electric motor. Additionally, if the actuation means 72 used were air bellows 7 and the sensor 4 a photocell combined with a light source, then the individual control means 70 could be an electric circuit combined with a solenoid valve. The electric circuit would use the output of the photo cell as necessary to cause the solenoid air valve to operate. This circuit could cause either the air valve to close when a package is detected or the valve to open when no package is detected.

The pressurized air controlled by each sensor valve 5 is provided from a pressurized air system (not shown). Each inlet line 11 connects the respective sensor valve 5 to airline 12. With a particular sensor valve 5 in the open position, pressurized air is provided to each air bellows 7 in the individual zone Za associated with the particular sensor valve 5 through bellows line 15. When the air bellows 7 in a particular individual zone Za are pressurized, the associated driver roll (s) 6 contact their respective pair of conveyor rolls 2. If the respective sensor valve 5 is closed, then the air in the associated bellows 7 and associated bellows line 15 is connected by sensor valve 5 to a respective valve exhaust 13 and thence to exhaust line 14. Exhaust line 14 may be vented to atmosphere or connected to further control systems.

Consequently, each sensor valve 5 will cause the associated driving roll (s) 6 to disengage or cease providing rotating force to the associated conveyor rolls 2 when the associated individual sensor 4 detects a package on conveyor 1. Furthermore, each sensor valve 5 will cause the associated driving rolls 6 to engage or provide a rotating force to the associated conveyor rolls 2, when the associated individual sensor 4 detects the absence of a package on conveyor 1.

In Figure 4, three substantially identical individual zones Zal, Za2, and Za3 are shown with like parts having like index numerals followed by"a"for zone Zal, a "b"for zone Za2, and a"c"for zone Za3. Sensor valves 5a, 5b, and 5c are connected by inlet lines 1 la, 1 lb, and I I c, respectively, to air line 12 from a source (not shown) of pressurized air. Valves 5a, 5b, and 5c are also connected by exhausts 13a, 13b, and 13c, respectively, to exhaust line 14. Additionally, air valve 5a physically located in individual zone Zal of Figure 4 has an outlet port connected by bellows line 15a to bellows (not shown) of the next adjacent upstream zone (not shown). In a similar fashion, the sensor valve 5b actuated by sensor roll 8b, both physically located in zone Za2, has an output port connected by bellows line 15b to the bellows 7a in zone Zal, as shown in Figure 4. Sensor valve 5c actuated by sensor roll 8c (both located in zone Za3) has an output port connected by bellows line 15c to bellows 7b in zone Za2. It will be understood that the bellows 7c of zone Za3 will be controlled by sensor valve (not shown), and sensor (not shown) located in next adjacent downstream individual

zone (not shown) via bellows line 15c. It is therefore evident that the sensor and pneumatic sensor valve that controls the bellows mechanism for a particular zone Za are typically located in a downstream individual zone Za (n+l).

As indicated above, when sensor rolls 8a, 8b and 8c are in their normal positions as shown in Figure 4, their respective pneumatic sensor valves 5a, 5 b and 5c will supply air from line 12 to their respective sets of bellows. When one sensor roll 8a, 8b or 8c is shifted to its depressed position by the passage of a package thereover, the bellows 7 associated with that sensor roll 8 will be connected to their respective exhaust 13a 13b, and 13c. If the exhaust is vented, then those bellows will not hold their driver rolls in engagement with conveyor rolls, and the conveyor rolls will no longer be driven.

Unified Control Zones: As discussed briefly above, the overall conveyor 1, in addition to being divided into individual zones Za, is also divided into larger unified zones Zb. Each unified zone Zb may contain any number of individual zones Za. Typically, each unified zone Zb contains from about 4 to about 6 individual zones Za. Preferably, all of the unified zones Zb of a conveyor will contain the same number of individual zones Za. In Figure 6a, an exemplary unified zone Zb2 is illustrated together with individual zone Za4 of unified zone Zbl and individual zone Zal of unified Zone Zb3. The unified zone Zb2 shown comprises four individual zones Zal, Za2, Za3, and Za4. The individual zones Zal, Za2, Za3, and Za4 are each substantially the same as the individual zones Zal, Za2 and Za3 illustrated in Figure 4. For purposes of simplicity, however, each individual zone Zal, Za2, Za3, and Za4 shown in Figure 6a is diagrammatically indicated by a sensor valve 5, a sensor roll 4, a pair of conveyor rolls 2 and one driver roll 6 of drive means 3. In addition to the components from each individual zone, a unified zone has a unified zone control 74, and at least one unified sensor 40. Typically, the initial unified sensor 40 will send an output signal to the unified zone control 74 in the adjacent upstream unified zone. The unified sensor 40, however, may provide an output to any unified zone desired.

The unified control 74 may be any device that is compatible with the unified sensor 40 selected. Additionally, unified control 74 typically is capable of providing an override signal or output to each individual control 70 in a particular unified zone Zb. Alternatively, the override signal could be provided to each individual control 70 that controls conveyor rolls 2 in the particular unified zone Zb, or directly to each drive means 3 in the particular unified zone Zb.

The output from unified control 74 typically will depend on the condition of a selected unified zone. The selected unified zone, preferably, is the adjacent downstream unified zone. However, the selected unified zone may be any unified zone desired by the operator. When the selected unified zone is not in the transportation mode the unified control 74 will override the associated individual controls 70 upon receiving an output from its respective unified sensor 40 indicating the absence of a package at unified sensor 40. When each individual control 70 for the particular unified zone Zb has been overridden, each drive means 3 associated with the overridden individual controls 70 will be engaged by actuation means 72.

When a package is detected at a particular unified sensor 40, the associated unified control 74 returns control of its associated individual zones Za to their associated individual zone controls 70. However, if the selected unified zone is in the transportation mode, then the unified control 74 is actuated to override the associated individual controls 70. Thus, if the selected unified zone is in the transportation mode the present unified zone is also in the transportation mode. To prevent or limit the cycling of the conveyor a time delay 78 may be used. This time delay 78 would delay the deactivation of unified control 74 for a set time period after either the unified sensor 40 detects a package and the selected unified zone is not in the transportation mode.

This process is shown in unified zone flow chart 200, shown in Figure 7a.

The unified zone flow chart 200 provides a flow chart of the control process used in unified zone Zb and discussed above.

Unified control 74 may be an electronic, electro-pneumatic, pneumatic, or mechanical control. Preferable, unified control 74 is a pilot actuated air valve 16.

Unified sensor 40 may be any sensor type discussed for individual sensor 4.

Typically, unified sensor 40 will be the same type of sensor as is used for individual sensor 4. The time delay may be any an electronic, electro-pneumatic. pneumatic, or mechanical time delay. Preferably, time delay 78 is a pneumatic time delay formed using a check valve installed in a by-pass line around a restriction. _ The left-handmost individual zone Zal of unified zone Zb2 is provided with the same index numerals as the left handmost individual zone Zal of Figure 4. The conveyor rolls 2a are capable of being driven by drive means 3 comprising a driven roll 6a. The actuation means 72 which activates/deactivates the drive means, is a bellows element 7a. The sensor 4a comprises a sensor roll 8a, a pair of rocking arms 9a, each arm 9a being pivoted at 10a to its respective adjacent conveyor side frame member (not shown). The individual control means 70 is a pneumatic sensor valve 5a. The remaining three individual zones Za2, Za3, and Za4 of unified zone Zb2 are substantially identical to the zone just described and like parts have been given like index numerals followed respectively by"b","c"and"d".

Figure 6a also illustrates the adjacent individual zone Za4 of the adjacent upstream unified zone Zbl. Similarly, the adjacent individual zone Zal of the adjacent downstream unified zone Zb3 is also shown. Like parts zone Za4 of unified upstream zone Zbl are given like index numerals followed by"d". Like parts of zone Zal of unified downstream zone Zb3 are given like index numerals followed by"a".

As is the case in the embodiment shown in Figure 4, the sensor valves 5a, 5b, 5c, and 5d are connected by inlet lines 1 la, 11 b, 11 c, and 11 d respectively, to air line 12 from a source of pressurized air. Each sensor valve 5a, Sb, 5c, and 5d is connected to the bellows of the upstream adjacent individual zone by bellows lines 15a, 15b, 15c, and 15d, respectively. It will be noted that the sensor valve 5a of unified zone Zb2 controls bellows 7d of individual zone Za4 of unified zone Zbl (next upstream adjacent zone). Similarly, the bellows 7d of zone Zb2 is controlled by sensor valve 5a

located in individual zone Zal of unified zone Zb3. The sensor valves 5a, 5b, 5c, and 5d are connected to exhaust line 14 by respective exhausts 13a, 13b, 13c, and 13d.

Typically, exhaust line 14 is connected to the exhausts 13 of control valves 5 physically located in the unified zone Zb. Alternatively, exhaust line 14 may be connected to the exhausts 13 of control valves 5 that are associated with or control the individual zones Za in the unified zone Zb. Exhaust line 14 is connected to pilot valve 16. Pilot valve 16 is also connected to pressurized air line 12 with supply line 17 and may be connected to main exhaust line 18 with exhaust connection 19. Both main exhaust line 18 and exhaust connection 19 are optional. If these air lines are installed the main exhaust 18 must be of sufficient size so that pressure does not build up in the line and inadvertently override on of the air pilot valves connected thereto.

Additionally, if main exhaust line 18 is installed it may be used to activate the slug discharge mode.

The pilot portion of valve 16 is connected to the output or signal from a unified sensor 40. Sensor 40 may be located anywhere along conveyor 1 where it is desired to control unified zone Zb. Typically, the unified sensor 40 is one of the individual sensors 4 combined with its associated individual control 5. Thus, the signal from sensor valve 5 selected to be part of unified sensor 40 will control both the pilot valve 16 and the bellows 7 associated with the selected sensor valve 5.

Typically, the pilot portion of pilot valve 16 will be connected to a selected bellows line 15 of the adjacent downstream unified zone Zb. Preferably, the pilot portion of pilot valve 16 is connected to the bellows line 15 associated with the second individual zone Za in the adjacent downstream unified zone Zb.

Pilot air valve 16 will open when it receives a signal or output of unified sensor 40 indicating either that there are no packages at unified sensor 40 or that the selected unified zone is in the transportation mode. With pilot air valve 16 open, air pressure is applied through exhaust line 14 to respective exhausts 13 of sensor valves 5 associated with pilot valve 16. This compressed air will then be applied to the respective bellows 7 through these sensor valves 5. Consequently, these sensor valves

5 and their associated sensors 4 will be overridden since the drive roller 6 will drive conveyor rolls 2 even if the sensor 4 that controls the particular individual zone Za detects a package on conveyor 1.

According to the present invention, a pilot actuated valve 16 is provided for each unified zone. Such a pilot actuated valve 16 for unified zone Zbl is shown in Figure 6a at 16'and for unified zone Zb2 at 16". Thus, for zone Zbl pilot value 16'is connected to pressurized air line 12 with supply line 17'and to main exhaust line 18 with exhaust connection 19'. The pilot portion of pilot actuated valve 16'is connected to the bellows line 15c of unified zone Zb2. All of the sensor valves 5 physically located in unified zone Zb2 will be connected to an exhaust line 14"which, in turn, is connected to pilot actuated valve 16". Pilot actuated valve 16"is connected to pressurized air line 12 with supply line 17"and to main exhaust line 18 with exhaust connection 19". Finally, each of sensor valves for a particular unified zone 5a, 5b, 5c and 5d have their exhaust ports connected to exhaust line 14"by respective exhausts 13a, 13b, 13c and 13d.

The arrangement shown in Figure 6a enables the mode of operation of the unified zone Zb to be changed. When pilot actuated valve 16 is not actuated, the zone Zb will act as a singulation zone in substantially the way as the device shown in Figure 4. However, when pilot valve 16 is actuated, valve 16 will override the sensor valves 5 of all of the individual zones Zal-Za4 of a unified zone Zb. In other words, valve 16, when actuated, will override sensor rolls 8a. 8b, 8c and 8d, and sensor valves 5a, 5b, 5c and 5d by directing pressurized air through lines 15,14, and 13.

Thus, if the unified sensor 40 of the next downstream unified zone Zb (n+l) does not sense the presence of a product or the next downstream unified zone Zb (n+1) is in the transportation mode, the unified zone Zb (n) will convert from a singulation zone to a transport zone, wherein all of the conveyor rolls of the unified zone Zb (n) of Figure 6a are actuated so long as pilot valve 16 is actuated.

When the unified sensor 40 that actuates pilot valve 16 detects the presence of a package and the next downstream unified zone Zb (n+l) is not in the transportation

mode, the pilot actuated valve 16 will close and the adjacent upstream unified zone Zb (n) will be converted to a singulation zone wherein each drive roll 6 in each of the individual zones Za in unified zone Zb (n) are actuated if their associated sensor valves 5, located in an adjacent downstream zone, do not receive an output or signal from sensor 4 indicating the presence of product on the conveyor 1.

Specifically the mode of operation of the unified zone Zbl of Figure 6a can be automatically changed between accumulation, singulation, and transportation modes.

When pilot actuated valve 16'is not actuated the zone Zbl will act as a singulation zone as discussed above. However, when valve 16'is actuated by its pilot portion connected to the output of sensor valve 5c for unified zone Zb2 (the adjacent downstream unified zone Zb (n+1)), valve 16'will override the individual control means 5 physically located in unified zone Zbl. Similarly, the mode of operation of the unified zone Zb2 of Figure 6a can be automatically changed between accumulation, singulation, and transportation modes. When pilot actuated valve 16" is not actuated the zone Zb2 will act as a singulation zone as discussed above.

However, when valve 16"is actuated by its pilot portion connected to the output of a sensor valve 5c (not shown) for unified zone Zb3 (the adjacent downstream unified zone), valve 16"will override the individual controls 5a, 5b, 5c and 5d, respectively.

Thus, valve 16", when actuated, will override sensor rolls 8a, 8b, 8c and 8d by directing pressurized air through respective lines 15,14", and 13. In other words, valve 16", when actuated, can override sensor rolls 8a, 8b, 8c, and 8d and sensor valves 5a, 5b, 5c, and 5d by directing pressurized air through their respective lines 15, 14", and 13. Thus, if the unified sensor 40, a pre-selected sensor 4 of the next adjacent downstream unified zone Zb3, does not sense the presence of a product or unified zone Zb3 is in the transportation mode, then the unified zone Zb2 of Figure 6a will convert from a singulation zone to a transport zone, wherein all of the conveyor rolls 2 of the unified zone Zb2 of Figure 6a are actuated so long as pilot valve 16"is actuated.

When the unified sensor 40, pre-selected downstream sensor valve 5c of unified zone Zb3, which actuates pilot valve 16"detects the presence of a product by

means of its sensor roll 8b and the unified zone Zb3 is not in the transportation mode, then the pilot actuated valve 16"will close and the unified zone Zb2 of Figure 6a will switch to a singulation zone.

When a sensor 4 in the adjacent downstream individual zone shown in Figure 6a constantly detects the presence a package on the conveyor 1, the conveyor roll 2 of the upstream individual zone will no longer be powered and each individual zone Zal, Za2, Za3 and Za4 will become an additional accumulation zone. When all in the individual sensors 4 that control individual zones within unified zone Zb2 constantly detect the presence of a package on conveyor 1, then unified zone Zb2 will become an additional accumulation unified zone.

Two Sensor Unified Zone Control Figure 6b illustrates a two sensor control system for a unified zone Zb. The unified control system of Figure 6a is improved by the addition of a second unified sensor 42. The use of a first unified sensor 41 and the second unified sensor 42 improves the reliability and in some installations may improve the throughput of the conveyor system. Once the unified control 74 receives simultaneous, or close to simultaneous, signals from unified sensor 41 indicating the absence of a package at sensor 41 or that the downstream unified zone Zb (n+1) is in the transportation mode, and from unified sensor 42 indicating the absence of a package at sensor 42, unified control 74 will latch. Once unified control 74 has latched, only one of the unified sensors 40 needs to provide a signal indicating the absence of a package at the sensor 41 or 42 or a signal indicating that the downstream unified zone Zb (n+l) is in the transportation mode to maintain an output from unified control 74 that will override the associated individual controls 70. When both unified sensors 40 detect a package and downstream unified zone Zb (n+l) is not in the transportation mode, then unified control 74 will unlatch and permit the associated individual controls 70 in the unified zone Zb (n) to resume control of their associated individual zones Za.

The control logic of the two sensor zone control system is altered from that shown in Figure 7a to require both unified sensors 41 and 42 for a particular zone to simultaneously, or close to simultaneously detect the absence of packages on conveyor 1 for that particular unified zone to switch to the transportation mode.

Alternatively, the unified zone may switch to the transportation mode if a selected unified zone is in the transportation mode and unified sensor 42 that controls the particular unified zone detects the absence of a package at unified sensor 42. This process is illustrated in a two sensor unified zone flow chart 202 shown in Figure 7b and provides a diagram of the control process used by the two sensor unified control zone.

As with the unified and individual control systems discussed above, it is possible to manufacture the system out of electrical components, a combination of electrical and pneumatic components, mechanical, or, as is shown in Figure 6b, pneumatic components. Currently the pneumatic configuration appears to be the most economical, and is described below.

The pneumatic control system shown in Figure 6a is modified as follows. The supply line 17 to pilot valve 16 is disconnected from air line 12, and is connected to a selected bellows line 15 for the associated sensor valve 5 and individual sensor 4 that will be used as a first unified sensor 41. The second unified sensor 42 will also be made up of a selected sensor 4 and its associated sensor valve 5. The output of this second unified sensor 42 is disconnected from its associated bellows line 15 and is connected via pilot control line 24 to one inlet of shuttle valve 26. Connected to a second inlet of shuttle valve 26 is shuttle line 28. Shuttle line 28 connects the outlet of pilot valve 16 to one inlet of shuttle valve 26. The shuttle valve 26 will direct the compressed air from whichever line 24 or 28 has the highest pressure to the pilot of pilot valve 16 through pilot line 30. Pilot line 30 is connected to the outlet of shuttle valve 26. Exhaust line 14 is disconnected from pilot valve 16 and is connected to pilot line 30. The bellows line 15 that was disconnected from its associated sensor valve 5 is connected to the exhaust line 14. Finally, exhaust 13a is disconnected from

exhaust line 14 and the individual control 5a that is part of second unified sensor 42 is vented to atmosphere.

Thus, when there is an absence of packages at the first unified sensor 41 or a selected unified zone is in the transportation mode, there will be a supply of compressed air to pilot valve 16. When the second unified sensor 42 also detects the absence of a package pilot valve 16 will open. Thus, there will be a supply of compressed air directed through pilot control line 24 to shuttle 26. Shuttle 26 will shift to permit the compressed air signal into pilot line 30 and will close off shuttle line 28. With compressed air supplied to pilot line 30, the pilot valve will open and direct the compressed air from supply line 17 through pilot valve 16 to shuttle line 28.

At this point, pilot valve 16 will be latched since, if the second unified sensor 42 detects a package and the compressed air is removed from line 24, shuttle 26 will reposition and permit compressed air to flow from shuttle line 28 to pilot line 30, maintaining pilot valve 16 in the open position and the sensor valves 5 associated with pilot valve 16 will continue to be overridden. Thus, once both unified sensors 40 detect the absence of packages, then valve 16 will override its associated sensor valves 5. Therefore, when a signal has been received from both unified sensors 40, detecting an absence of packages on the conveyor 1 pilot valve 16 will latch.

Alternatively, pilot valve 16 can latch if the selected unified zone is in the transportation mode and the second unified sensor 42 detects the absence of a package.

Thereafter, only one of the two unified sensors 40 are required to detect a package on the conveyor 1 or the selected unified zone is in the transportation mode to permit pilot valve 16 to continue to override the sensor valves 5 associated with the pilot valve 16. When both unified sensors 40 detect the presence of a package on conveyor 1 and the selected unified zone is not in the transportation mode, then pilot valve 16 will close. When pilot valve 16 is in the closed position, exhaust line 14 will now be vented to atmosphere. Alternatively, exhaust line 14 may be connected to main exhaust 18 via pilot valve 16 and exhaust connection 19. With exhaust line 14 directed either to atmosphere or to main exhaust line 18, control of each individual

zone Za (n) will be returned to the sensor 4 and sensor valve 5 in the downstream adjacent individual zone Za (n+1).

Because of the connection of the bellows line that was associated with the second unified sensor 42 is connected to the output of the shuttle valve 26 when the second unified sensor 42 detects the absence of a package on conveyor 1, unified sensor 42 will activate not only its associated drive means 3 for its associated individual zone Za, but will also override the sensor valves 5 for all individual zones associated with pilot valve 16. The activation of all drive means 3 in unified zone Zb is a departure from the process shown in the two sensor flow chart 202. This small deviation is an acceptable compromise to produce an economical pneumatic control system.

Additional Unified Sensors The use of one or two unified sensors to control the operation of a particular unified zone as described above is believed to represent the best/most cost effective method of designing this conveyor control system for pneumatic control. As discussed above, a pneumatic control system is currently believed to be the most cost effective control system. If an electronic or computer controlled system was used that monitored the position of each individual zone sensor, then it would be a simple matter to extend the control method discussed above to a system in which each sensor served as both an individual zone sensor and as a unified zone sensor. The use of additional unified zone sensors would enhance the reliability and flexibility of the conveyor control system.

Singulation Discharge Singulation discharge means the discharge of a one package or a group of packages (the group of packages may fill an entire individual zone) at a time from a unified zone Zb until the packages or groups of packages in the unified zone Zb have been spaced apart. Once all the packages or groups of packages in zone Zb have been properly spaced, the singulation control 76 will override the individual controls 70

and individual sensors 4 and convert or switch unified zone Zb into the transport mode. In a typical discharge scenario, the unified zones Zb downstream of the unified zone Zb operating in the singulation mode would all be in the transport mode.

Similar to the two prior conveyor control systems, there is a multitude of methods of providing this type of conveyor control. These methods would include electrical control systems, electro-mechanical control systems, electro-pneumatic control systems or pneumatic control systems. The sensors utilized as unified zone sensors 40 can be any of the sensor types discussed above for the unified zone Za.

Singulation control 76 may be any device compatible with the selected unified control 74 and the selected actuation means 72. The singulation control 76 used in the pneumatic system shown in Figure 6c is typically a singulation pilot valve 34.

After one or more unified zones Zb have accumulated packages, and it is desired to discharge those packages on a conveyor set up for singulation release, the discharge of the packages is initiated. Initially, each individual zone Za will operate in singulation mode. Once the unified sensor 42 for the upstream unified zone Zb (n- 1) indicate the absence of packages, then the current zone Zb (n) will be shifted into the transport mode by singulation control 76 overriding the individual controls 70 in the current zone Zb (n) with singulation control 76. This override is identical to the override discussed for both the unified zone control and the two sensor unified zone control. The singulation release flow chart 204 of Figure 7c provides a process flow chart describing this process.

With reference now to Figure 6c, which shows one embodiment of a singulation release control system for illustrative unified zones Zbl and Zb2 that provides for singulation release. The pneumatic system is currently believed to be the most economical method of providing this type of conveyor control. The specific embodiment shown in Figure 6c is a modification of the two sensor unified zone control shown in Figure 6b. The two sensor unified zone control system modifications are discussed below.

Generally, exhaust line 14 is disconnected from pilot valve 16, and is connected to the outlet of singulation pilot valve 34. The inlet of singulation pilot valve 34 is connected to the pilot line 30 via singulation inlet line 32. The exhaust of singulation pilot valve 34 may be vented to atmosphere or connected to main exhaust 18 by exhaust conduit 36. The pilot portion of singulation pilot valve 34 is connected to singulation shuttle valve 46 via singulation line 44. Singulation line 44 is connected to the outlet of shuttle valve 46. One inlet of singulation shuttle valve 46 is connected via latch line 48 to exhaust line 14. The second inlet to shuttle valve 46 is connected to a pilot control line 24 from the unified sensor 42 of the next adjacent upstream unified zone Zb (n-1) via singulation release 50. Additionally, the bellows line 15 connected to exhaust line 14 is disconnected from exhaust line 14 and connected to the outlet of a bellows shuttle valve 54. One inlet to bellows shuttle valve 54 is connected to pilot control line 24 via bellows sensor line 52. The second inlet to shuttle valve 54 is connected to exhaust line 14 with a bellows exhaust line 38.

Specifically for unified zone Zb2, unified sensor 41"is the individual sensor 4b combined with sensor valve 5b in individual zone Za2 of unified zone Zb2.

Similarly, unified sensor 42"is the individual sensor 4a combined with sensor valve 5a for individual zone Zal of unified zone Zb2. The pilot valve 16'for unified zone Zbl is connected to unified sensor 41"by supply line 17'and bellows line 15a of unified zone Zb2. The exhaust port of unified control 16'is connected to main exhaust line 18 with pilot exhaust 19'. Unified sensor 42"is connected to one inlet of shuttle valve 26'with pilot control line 24". Connecting pilot control line 24"to the singulation shuttle valve 46" (the singulation shuttle valve for the downstream singulation control) is singulation release line 50". The outlet of pilot valve 16'is connected to a second inlet of shuttle valve 26'with shuttle line 28'. The outlet of shuttle 26'is connected to the pilot portion of pilot valve 16'with pilot line 30'. Also connected to pilot line 30'via singulation inlet line 32'is singulation pilot valve 34'.

The exhaust port of singulation pilot valve 34'is connected to main exhaust line 18 by singulation exhaust 36'. The outlet of singulation pilot valve 34'is connected to exhaust line 14'. Singulation pilot line 44'connects the pilot portion of singulation

pilot valve 34'to the outlet of singulation shuttle valve 46'. One inlet of singulation shuttle valve 46'is connected via shuttle latch line 48'to exhaust line 14'. Connected to the second inlet of singulation shuttle valve 46'is singulation release line 50'.

Bellows line 15a is connected to the outlet of bellows shuttle 54'. Bellows sensor line 52'connects one inlet of bellows shuttle valve 54'to pilot control line 24". Bellows exhaust 38'connects a second inlet of bellows shuttle 54'with exhaust line 14'.

The connections for the singulation pilot valve 34"and pilot valve 16"for unified zone Zb2 are identical to those described for zone Zbl with the exception that the"'"has been replaced with"""and the"""with"""".

This pneumatic singulation release control for unified zone Zb2 will operate as described below.

When unified sensor 41"indicates an absence of packages, a supply of compressed air will be provided via bellows line 15b for unified zone Zb2, and pilot supply line 17'to air pilot valve 16'. When unified sensor 42"indicates a lack of packages, then compressed air will be supplied via pilot control line 24"to both shuttle valve 26'and to singulation release line 50", which connects to the singulation pilot valve 34". Thus, with unified sensor 42"providing a signal indicating a lack of packages, the singulation pilot valve 34"will be open. With both unified sensors 41"' and 42"'indicating a lack of packages to unified control 16", compressed air would be supplied via singulation supply 32"to the inlet of singulation pilot valve 34". Unified zone Zb2 at this point would now shift to the transportation mode. Unified zone Zbl will remain in the singulation mode until unified sensor 42' (not shown) associated with unified zone Zbl sends a signal via pilot control line 24'and singulation release line 50'to singulation pilot valve 34'indicating that unified sensor 42'for unified zone Zbl is not detecting a package. Once singulation control 34'for zone Zbl receives this signal, singulation shuttle valve 46'will shift and permit the compressed air to actuate the pilot of singulation pilot valve 34', opening singulation pilot valve 34'.

When singulation pilot valve 34'opens and compressed air is provided from pilot valve 16'through singulation pilot valve 34'to exhaust line 14', overriding sensor

valves 5a, 5b, 5c and 5d (only 5d is shown for unified zone Zbl) for unified zone Zbl.

The overriding of these sensor valves 5 will provide compressed air to bellows 7 associated with the respective sensor valves 5. With compressed air provided to the respective bellows 7, drive roll 6 associated with the activated bellows 7 will engage the associated conveyor rolls 2, causing zone Zbl to shift into the transportation mode.

Sensor Down In many conveyor applications using mechanical sensors (sensors activated by a package or object physically touching and moving the sensor) it is desired to lower the sensors 4 and 40 so the packages on conveyor 1 do not constantly hit or contact the sensors 4 or 40 when the unified zone Zb is in the transportation mode. Referring to Figure 4, it is usual practice to mount the sensor valves 5 on one side of the conveyor adjacent the lower end of the rocking arms 9. In Figure 4, these rocker arms and these sensor valves 5 should be considered as mounted on the inside surface of that side frame of the conveyor furthest from the viewer. In Figure 8, a unified zone Zb with four individual zones Za is once again shown. In this instance, the inside surface of the near side frame of the conveyor 1, i. e. that side frame nearest the viewer of Figure 4 is shown. The sensor rollers 8a, 8b, 8c, and 8d are shown mounted on their respective rocking arms 9a, 9b, 9c, and 9d, respectively. These arms are pivoted to the inside surface of the other side frame of the conveyor, i. e. the side frame nearest the viewer of Figure 8. Pivoting of these rocking arms 9 is shown at 10a, lOb, 10c, and 10d in Figure 8. Mounted on the same near side wall of the conveyor are air cylinders 22a, 22b, 22c and 22d. One air cylinder 22 for each arm 9a, 9b, 9c, and 9d, respectively. These cylinders are connected to cylinder supply 25 via cylinder supply lines 23a, 23b, 23c and 23d. Cylinder supply 25 connects cylinder supply lines 23 to exhaust line 14. Exhaust line 14 connects to the outlet port of pilot valve 16.

Consequently, when pilot valve 16 is actuated and converts unified zone Zb from a singulation zone to a transportation zone by overriding the associated individual sensor valves 5, all of the associated sensor rolls 8a, 8b, 8c and 8d will be held in their downward-depressed positions by cylinders 22a, 22b, 22c and 22d. This sensor down

feature, wherein the sensor rolls are held their lowermost position when their respective unified zone Zbl operates as a transport zone, prevents the sensor rollers from being pushed to their lower position by each package that travels over them.

This feature not only saves wear and tear on the sensor mechanism, it also permits the conveyor to run more quietly and smoothly. When the pilot valve 16 is unactuated, each of the sensor down air cylinders 22a, 22b, 22c and 22d will be connected via cylinder supply line 23, cylinder supply 25, exhaust line 14, and pilot valve 16 to main exhaust 18. With cylinders 22 vented, the respective sensors 4 will return to a normal position with sensor rolls 8 maintained slightly above conveyor rolls 2 as discussed above.

Slug Release Slug release is a discharge mode that permits the operator to place selected zones of the conveyor proximate the end of the conveyor into the transport mode.

Typically, the zones currently in the accumulation mode would be the zones switched to the transportation mode. This feature is common to many accumulation conveyor systems. The slug release may be installed on any one of the conveyor embodiments disclosed. This feature may be effected by any of the control systems embodied in the prior art. Additionally, a slug release may be implemented by pressurizing the main exhaust line 18 if installed. Pressurizing this line would cause the individual controls 5 to be overridden with the results discussed above.

In summary, numerous benefits have been described which result from employing the concepts of the invention. The foregoing description of a preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiment was chosen and described in order to best illustrate the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.