Door operator control system and method

Information

  • Patent Grant
  • 6388412
  • Patent Number
    6,388,412
  • Date Filed
    Tuesday, May 9, 2000
    24 years ago
  • Date Issued
    Tuesday, May 14, 2002
    22 years ago
Abstract
An operator control system for controlling the operation of an electric motor driven door or gate operator unit having a speed reducing gear drive mechanism and a brake unit for positive braking of the motor output shaft. A programmable microcontroller is operably connected to a motor drive circuit with interlock relays to energize the operator unit drive motor for rotation in opposite directions. The motor drive circuit is interconnected with a motor watchdog circuit to effect motor shutdown if the microcontroller malfunctions. The motor drive circuit is operably connected to a brake release circuit to prevent motor operation unless the electrically operated brake is energized to release braking of an operator output shaft. The microcontroller receives input signals from manually or radio-controlled door open, close and stop switches and from door position limit switches. The microcontroller is connected to a non-volatile memory for storing door mid-stop time delay values, braking rates, a door position limit overrun signal, a door cycle count, door reversals upon receiving an obstruction detector signal and error codes associated with door operator and control system malfunctions. The door may be operated to provide a down position limit overrun, progressive braking and a mid-stop set position by time based signals. The electrically operated brake may be controlled on a variable duty cycle to provide smooth braking action in both directions of movement of the door.
Description




FIELD OF THE INVENTION




The present invention pertains to a control system for a motor driven door operator, primarily intended for industrial type doors, including sectional upward acting or rollup doors, gates and similar closures, and methods of controlling the door operator.




BACKGROUND




Motor operated doors particularly adapted for industrial applications desirably include motor controls which facilitate ease of operation of the door and provide for a long operating life in rigorous operating conditions. One type of door operator that has been developed for use with the present invention is operable to be driven by electric motors and may be adapted to automatically close in the event of a power failure or upon receiving a remote control signal, be manually operated to open or close and be adapted for use with motors of various power capacities and electric power sources. Still further, the operating requirements for commercial or industrial doors and gates have dictated other improvements in control systems for motor operated closures, including upward acting doors, in particular. The present invention provides certain improvements needed in this art.




SUMMARY OF THE INVENTION




The present invention provides an improved door operator control system for controlling a motor driven operator for doors, gates and upward acting doors, in particular.




In accordance with one aspect of the present invention a control system is provided which includes a programmable microcontroller and associated control circuits and is adapted for use with door operators driven by electric motors of various power capacities and power sources. The control system includes protective circuit elements to avoid damage to the control system caused by power source voltage transients, including overvoltages resulting from connection of a transformer of the wrong voltage rating, or major voltage surges such as induced by nearby lightning strikes.




In accordance with another aspect of the present invention a door operator control system is provided which includes improvements in circuitry for receiving signals indicating door travel limits, an advantageous arrangement of operator control elements for controlling a microcontroller unit of the control system and circuits for input signals from various sources including external interlock input signals and remote control input signals.




The control system of the present invention also includes circuits for connecting a microcontroller to motor drive relays or contactors including an interlock feature, a motor drive “watchdog” circuit, a motor drive status feedback circuit, control circuitry for controlling a door operator which includes an operator brake, and an emergency operator shutdown circuit.




The control system of the present invention further includes a keypad for inputting control signals and calibration signals to a microcontroller via a serial communication bus to control door functions including door overrun of a position limit, braking rate of the operator brake, a mid position stop, clearing maximum run timers of the operator and correlating the motor direction of rotation with door direction of movement. The control system further includes a seven segment display and calibration indicators for displaying a condition code in the normal operating mode of the control system, calibration information when the control system is being operated in a calibration mode and error codes indicating a fault or error condition existing in the control system and the associated operator. The seven segment display includes a driver circuit including a multiplexed constant current source.




The present invention still further provides an improved method of operating a motor driven operator for opening and closing a closure device, such as an upward acting sectional or rollup door or a gate wherein improved braking action is imposed by and on the operator to control a braking rate of the door to minimize shock loads, wear and tear on the door and the operator, and to reduce noise associated with door operation.




The control system is also adapted to provide a method of operation which allows a door position limit overrun with variable progressively longer or shorter time delays between the time that a limit position is achieved and the door operator begins a braking procedure. In particular, when the door operator activates a switch determined to be the door down position limit switch, a user selectable time delay may be input to the controller, which time delay will delay motor shutdown and the onset of the braking procedure to allow the door bottom edge to seal against a floor or sill and without activating a door reversal or so-called safety reversal switch, which would otherwise cause an unintended reversal of the door.




Those skilled in the art will further appreciate the features and advantages of the door operator control system and method of operation as well as other important aspects thereof upon reading the detailed description which follows in conjunction with the drawings.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a perspective view of a door operator unit utilizing the control system of the present invention for opening and closing a vertical rollup type door;





FIG. 2

is an end elevation of the operator unit shown in

FIG. 1

;





FIG. 3

is a side elevation of the operator unit shown in

FIG. 1

;





FIG. 4

is a perspective view, partially cut away, of the operator unit shown in

FIGS. 1-3

; and





FIGS. 5A through 5G

comprise a circuit diagram of the control system of the present invention.











DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS




In the description which follows, like parts are marked throughout the specification and drawing with the same reference numerals, respectively. The drawing figures may not necessarily be to scale and certain components may be shown in somewhat generalized or schematic form, using conventional symbols, in the interest of clarity and conciseness. Major circuit elements commercially available are designated in a correlation table herein.




Referring to

FIG. 1

, there is illustrated conventional upward acting or rollup type door


12


including a closure member


14


guided for movement between opposed vertically extending guide tracks


16


and


18


for closing a door opening


20


. Upward acting door


14


is of a so-called rollup type and comprises a flexible curtain which is adapted to be wound around a cylinder or drum


22


supported for rotation between spaced apart brackets


24


and


26


suitably supported by a vertical wall


28


, as shown. The drum


22


is drivenly connected to an improved door operator unit adapted to be controlled by the control systems of the invention, and generally designated by the numeral


30


. The operator unit


30


includes a housing


32


adapted to be supported on the bracket


24


. A rotatable output shaft


34


is supported for rotation on the housing


32


and supports a conventional drive sprocket


36


for rotation therewith and drivingly connected to a sprocket


38


connected to the drum


22


by way of a conventional endless chain or belt


40


.




As shown in

FIGS. 2 and 3

also, the door operator unit


30


includes an auxiliary drive shaft


42


rotatably supported on housing


32


spaced from output shaft


34


and supporting a handwheel


44


comprising a chain sprocket drivably engaged with an endless link chain


46


in a known manner for rotating shaft


42


to raise or lower the door


14


, when required. Normally, in certain applications of the operator unit


30


, the door


14


will lower itself under certain conditions but may be required to be raised manually by rotating the handwheel


44


via the chain


46


or by direct engagement of the handwheel by a person attempting to raise the door through the operator unit


30


.




Referring further to

FIGS. 2 and 3

, the operator unit


30


includes an electric drive motor


48


,

FIG. 3

, including a housing


49


directly connected to the housing


32


and operable through suitable drive mechanism, to be described further herein, to drive output shaft


34


in opposite directions of rotation under command of the control system of the present invention. Major components of the control system are mounted in a housing, generally designated by numeral


50


. Housing


50


includes a removable cover


50




c


to provide access to the control system to be described further herein including a calibration keypad for the control system and a seven segment digital visual display board also associated with the control system.




The orientation of the operator unit


30


and the housing


50


therefor illustrated in

FIGS. 1 through 3

is exemplary. The operator unit


30


may be mounted with the housing


50


oriented to either side of the unit or the unit


30


may be inverted so that the housing


50


is above the motor


48


. A preferred orientation of the operator unit


30


is such that the housing cover


50




c


is facing either side of the operator unit to facilitate ease of removal and operation of the aforementioned calibration keypad disposed within the housing and which will be described in further detail hereinbelow. As further shown in

FIGS. 2 and 3

, housing


32


includes a suitable transverse mounting flange


33


for mounting the operator unit


30


on the bracket


24


, for example, using conventional mechanical fasteners, not shown.




Referring now to

FIG. 4

, the housing


32


includes an end face


35


opposite the flange


33


and including a flange


52


for securing motor


48


in assembly with the housing


32


using fasteners


52




a


, one shown. Motor


48


may be a conventional induction type electric motor including a rotary output shaft


54


adapted to be driveably connected to a coupling member


56


, including a “sun” gear


58


formed thereon. Sun gear


58


is drivingly connected to a differential planetary gear drive mechanism, generally designated by numeral


60


and disposed in a first cavity


31




a


formed in housing


32


and separated from a second cavity


31




b


by a transverse partition


32




a


. Drive mechanism


60


includes a first ring gear


62


supported in housing


32


adjacent a second ring gear


64


comprising an output gear of the planetary gear drive mechanism.




Referring to

FIG. 4

, output shaft


34


is disposed in sleeved relationship within a bearing hub


34




a


which is coupled to a suitable sealed bearing


34




b


supported for rotation in a support plate


32




p


releasably connected to the flange


33


by fasteners


32




f


. Moreover, shaft


34


includes a bearing bore


34




c


for receiving an idler shaft


34




d


which extends within a bore


56




c


of coupling/sun gear


56


,


58


to provide support for the coupling/sun gear and to journal the coupling/sun gear against lateral deflection away from its normal axis of rotation.




A commercially available electromagnetic disc type brake assembly


66


is supported within cavity


31




b


of housing


32


by motor housing


49


and includes a stator member


68


axially movable with respect to shaft


54


and coupling member


56


but nonrotatable relative to housing


32


. Brake assembly


66


may be of a type manufactured by API-Deltran, of Amherst, New York as their model BRP-30Y. A brake disc member


70


is mounted on coupling member


56


for rotation therewith and is operable to be engaged by an axially movable brake assembly stator member


68


to arrest rotation of coupling


56


and motor drive shaft


54


when the brake assembly


66


is de-energized. When brake assembly


66


is energized, stator member


68


is operable to release forcible engagement with brake disc


70


to allow same to rotate with motor drive shaft


54


and coupling/sun gear


56


,


58


. Brake assembly


66


includes a stationary back plate


67


forming a support for limiting axial movement of the disc


70


and stator


68


and to provide for engaging the disc


70


to provide the braking action. The coupling


56


includes a portion


56




a


having a non-circular outer surface for slidably engaging a corresponding non-circular bore in brake disc


70


to provide for drivingly-connecting the disc


70


to the coupling


56


but allowing some axial sliding movement between the disc


70


and the coupling/sun gear


56


,


58


.




Transverse partition


32




a


, intermediate the flange


33


and the end face


35


, separates the brake assembly


66


from the differential planetary drive mechanism


60


. Cavity


31




a


may be at least partially filled with a suitable lubricant which is prevented from escaping into cavity


31




b


by a disc like dam


31




c


, FIG.


4


. The planetary gear drive mechanism


60


includes carrier members


72


and


74


releasably connected to each other. Carrier members


72


and


74


support plural circumferentially spaced apart compound planet gears


78


for rotation on suitable shafts. An arrangement of three equally-spaced planet gears


78


is preferred. Compound planet gears


78


each include a first set of gear teeth


82


meshed with cooperating internal gear teeth


84


formed on ring gear


62


and a second set of gear teeth


86


adapted to mesh with internal teeth formed on output ring gear


64


. Planet gears


78


also mesh with sun gear


58


in driven relationship thereto. Accordingly, a substantial speed-reducing, torque multiplying effect is provided by the differential planetary gear drive mechanism


60


for rotating the output shaft


34


at a reduced speed with respect to the input shaft or coupling


56


and the motor output shaft


54


.




Ring gear


64


includes a transverse cylindrical disc-like hub portion and a central bore therethrough which is adapted to receive a torque limiting clutch hub


90


therein, which hub is drivingly coupled to output shaft


34


. In this respect, output shaft


34


has a hexagonal cross-section and is drivenly coupled to hub


90


which has a cooperating hexagonal cross section bore


91


formed therein. Clutch hub


90


is also provided with external threads formed thereon for threadedly connecting the hub to a torque limiting clutch adjustment plate


96


having cooperating internal threads.




If driving torque imposed on ring gear


64


exceeds a limit set by the torque limiting clutch described, the ring gear


64


will slip with respect to the hub


90


, rotationally, to prevent damage to the operator unit


30


as well as other structural components including the drive mechanism between the operator unit and the door closure member


14


and any object which may be caught between the door closure member and the floor of the door opening. However, since limit switch gear


100


is keyed for rotation with clutch hub


90


, and clutch hub


90


is positively engaged with shaft


34


, any slippage of the aforementioned clutch will not result in a loss of timing between a limit switch operably connected to the gear


100


and the position of a door driven by the operator unit


30


. By way of example, gear


100


is meshed with a pinion, not shown, which is operable connected to a suitable door position limit switch of a type commercially available from Sanwa Corporation, as Hokuyo model LMP-2, for example.




Ring gear


62


has a set of circumferential external teeth


62




a


formed thereon which are adapted to mesh with a ring gear release block


108


. In this way, when ring gear


62


is held stationary with respect to housing


32


, rotation of motor shaft


54


and coupling/sun gear


56


,


58


will effect rotation of ring gear


64


and output shaft


34


at a pre-determined reduced speed with respect to shaft


54


.




Accordingly, with brake assembly


66


applied to prevent rotation of motor output shaft


54


, operator unit output shaft


34


is also braked against rotation when ring gear


62


is held stationary with respect to housing


32


. However, ring gear release block


108


is operable to move out of engagement with ring gear


62


to allow same to rotate freely. Under these conditions, output shaft


34


, ring gear


64


and planet gears


78


will rotate together with ring gear


62


even though shaft


54


and coupling/sun gear


56


,


58


are held stationary by the brake assembly


66


.




Referring further to

FIG. 4

, ring gear release block


108


is supported in a removable housing


112


secured to the housing


32


by spaced apart fasteners


114


, one shown. An elongated lever


116


is pivotally connected to the housing


112


by pivot pin


116




a


and is engageable with an adapter member


117


for moving the release block


108


radially away from engagement with the ring gear


62


. A lever actuated switch


120


,

FIG. 4

, includes a lever actuator


122


engageable with a tang


108




b


formed on the release block


108


.




Accordingly, beginning with the condition wherein the block


108


is engaged with ring gear


62


, a first actuation of the handle


116


will effect disengagement of the block


108


from the ring gear


62


and a holding of the block in the disengaged position. Upon a second actuation of the handle


116


and release thereof, the block


108


will re-engage the ring gear


62


holding same against rotation with respect to housing


32


.




Under circumstances wherein the brake assembly


66


remains engaged to prevent rotation of shaft


34


, coupling/sun gear


56


,


58


and the output shaft


34


, the output shaft may be allowed to rotate together with all of the elements of the differential planetary gear drive mechanism, except the sun gear


58


, on actuation of the release block


108


to disengage from the ring gear


62


. This disengagement of the release block


108


from the ring gear


62


may take place manually upon manual actuation of the handle or lever


116


or in response to a control signal applied to an actuator, not shown, suitably connected to the lever. Switch


120


may, of course, be associated with the control system for the operator


30


to maintain a count of the number of actuations of the lever


116


and to indicate the condition of the operator, that is, whether or not the ring gear


62


has been released and allowed to rotate.




A control system, as shown in

FIGS. 5A-5G

, is disposed, substantially, in housing


50


except for a wall mounted unit indicated by numeral


200


in

FIG. 1

, which includes one or more control switches, to be described, operably connected to the control circuit in housing


50


by suitable electrical conductor means


200




a


or other interface means, not shown.




Referring now to

FIG. 5B

, there is illustrated a diagram comprising part of a control system


201


of the invention, including suitable multi-pin connectors


202


,


204


,


206


and


208


for connecting line voltage and a motor thermal protector feedback signal to motor


48


, depending on the voltage and phase of a power source, not shown, and adapted to be connected to the control system. The control system of the present invention is adapted to connect the operator drive motor with a selected one of sources of line voltage and phase characteristics, as indicated by the motor power supply control circuit of

FIG. 5B

, depending on motor characteristics and power availability. Accordingly, when a particular voltage and phase condition has been selected the appropriate connector


202


,


204


,


206


or


208


is utilized with the motor


48


. For purposes of discussion hereinbelow, primarily, the control system will be described for that situation wherein relay contacts


212


and


214


are used in conjunction with the motor and the control system.




Conductors


210




a


-


210




c


are connected to the appropriate connectors


202


,


204


,


206


and


208


by way of relay contact sets


212


and


214


or contactors,


216


and


218


, as shown. Actuators or coils for relay contacts


212


and


214


are illustrated in

FIG. 5C

, are part of a motor drive circuit therein shown and are designated by numerals


212




a


and


214




a


. A suitable resistor-capacitor transient protection circuit


222


,

FIG. 5B

, is operable to reduce any electrical arcing which might occur at the contacts


212


or


214


or contactors


216


or


218


, respectively.





FIG. 5B

also illustrates relay coils


216




a


and


218




a


operably connected to relay contactor sets


216


and


218


and to a control circuit conductor


226


which is connected to control circuitry shown in FIG.


5


C. When relays


212


and


214


are used, interlock relays


228


and


230


are controlled by respective actuators


228




a


and


230




a


, as shown in FIG.


5


C. As indicated in

FIG. 5B

, motors operating on 208/240VAC 3 phase, 480/575VAC 3 phase, 120VAC 1 phase or 208/240VAC 1 phase may be used in conjunction with the control system of the invention. Thanks to the configuration of the circuit shown in FIG.


5


B and the control circuits associated therewith and described herein, a control system is provided which is substantially universal within the parameters of power supply voltage and phase conditions indicated.




Referring to

FIG. 5A

, the control system


201


includes a connector


236


adapted to connect the control system to the line voltage available on conductors


210




a


,


210




b


and


210




c


. Conductors connected to the connector


236


are also connected to an array of metal oxide varistors


238


interconnected, as illustrated in

FIG. 5A

, across each of the power input conductors and between each conductor and earth ground to further protect the control system


201


from damage by power line transient conditions.




A connector


240


provides for connecting the control system


201


to a suitable transformer


242


, preferably a 24VAC 40VA, Class


2


transformer with a primary voltage matched to the power supply line voltage supplied to the control system. Transformer


242


is thus preferably connected by way of connector


240


to a circuit board, not shown, on which the control elements indicated herein are mounted. Transformer output or secondary conductors


242




a


and


242




b


are connected to a bridge rectifier circuit


244


and appropriate capacitor filters, and transient protection components, indicated generally at 246 to supply 24VDC power output at conductors


248




a


and


248




b


. A 5VDC regulated power supply circuit


250


, including a voltage regulator


250




a


is connected to the 24VDC power circuit by way of transistor


252


(Q


2


) to provide a pre-regulation function. Regulated 5VDC power is available at conductor


254


. A fuse


256


is interposed in conductor


242




a


to protect the associated circuits and transformer secondary circuit for the transformer


242


.




As further shown in

FIG. 5A

, a voltage sensing circuit


260


is connected across the rectifier circuit


244


and is operable to apply a short circuit across the 24VDC power supply provided by the rectifier circuit, if the DC supply voltage should vary by a preset amount, thus causing fuse


256


to open and protect the control system from damage due to overvoltage. For example, if a transformer is connected to the control circuit of the wrong voltage rating or if major power line surges, such as those caused by nearby lightning strikes, are experienced, fuse


256


will open to protect the control system elements connected to the DC power supply rectifier bridge


244


.




Throughout the schematic diagrams of

FIGS. 5A through 5G

, several schematic reference symbols are shown for purposes of eliminating an excessive number of lines to indicate a conductive or signal transmission path. By way of example, in

FIG. 5A

, schematic reference or symbol


261


indicates a point at which a signal may be imposed on sensing circuit


260


to effect turning on a silicon controlled rectifier (SCR)


262


thereby creating a short circuit which will effect opening of fuse


256


when, for example, an emergency shutdown of the control system


201


is desired. Throughout the discussion herein and the drawing figures referred to in such discussion, the term “schematic reference” or “reference” will be used to indicate a so-called connector or point on a conductive path at which signals may be transmitted to or received from other points or control elements of the control system of the invention without showing a line therebetween.




Referring now to

FIG. 5D

, door travel limit indicator means comprising a switch unit


264


, may be associated with a door, such as the door


14


,

FIG. 1

, and operably connected to the operator unit


30


, as previously discussed, for providing suitable signals indicating when the door has reached an open or upper limit position and a closed or down limit position. These limit positions may be associated with a so-called clockwise (CW) and counterclockwise (CCW) direction of rotation of the door drum


22


, for example, or the output shaft


34


of the operator


30


and correspond to a clockwise or counterclockwise direction of rotation of the motor


48


. In all events, a signal indicating a position limit may be provided by limit switch unit


264


through a connector


266


to a conditioning circuit


268


for providing an output signal at schematic reference


270


. In like manner a signal from the limit switch unit


264


may be imposed through connector


266


on a second signal conditioning circuit


272


for output to schematic reference


274


. The “up” or door open and “down” or door close mode of operation associated with each limit switch signal may be selected by a user when calibrating the control system


201


.




In the exemplary embodiment shown, the actual limit switches in the limit switch unit


264


are configured as normally closed switches which operate to provide suitable control signals through the respective signal conditioning circuits


268


and


272


. Limit switch unit


264


may be of the type commercially available referenced hereinabove. A microcontroller unit associated with the control system and described hereinbelow will monitor the appropriate limit signal and when a limit signal is received the microcontroller is operable to stop the motor


48


and begin a braking cycle, applying the brake


66


to stop rotation of shaft


54


and output shaft


34


in a desired manner. Moreover, a user selectable time delay may be used in conjunction with control system


201


, as will be described further herein for the situation where the motor shutoff signal is received when either position of the door is reached. When the aforementioned time delay is completed the motor


48


is shutdown and the braking process begins. In particular, a door “down” or closed limit overrun feature is provided whereby the control system


201


permits a door having flexible door bottom edge seal or gasket to engage the floor without causing an unintended reversal of the door.




Still further, the aforementioned microcontroller also utilizes the limit switch input signals generated at the references


270


and


274


to monitor the limit position of the door opposite the direction of rotation of the motor. For example, if the motor


48


causes the operator unit


30


to move the door away from a limit position and the operator output shaft is running in a clockwise direction the controller will monitor the other (counterclockwise) limit for a signal. If the monitored limit does not respond within a short time of motor activation, the microcontroller will determine that a motor stall condition has occurred. The microcontroller will then effect shutoff of the motor and begin the braking process followed by displaying a suitable error code in a manner to be described further herein.




Referring further to

FIG. 5D

, the control system


201


may be operable to include only one user or operator controlled switch at the control unit


200


. This switch is indicated at


278


in FIG.


5


D and is associated with a signal conditioning circuit


280


to provide an output signal at schematic reference


282


. Operation of the switch


278


will effect operation of the motor


48


, and release of the brake


66


, to move the door


14


to the up or open position unless the door is already in that position, in which case the door will move to the opposite or closed position.




Referring still further to

FIG. 5D

, the control system


201


includes a programmable microprocessor, or so called microcontroller, previously mentioned, and generally designated by numeral


284


, which is operable to receive certain control signals and to generate other control signals to control operation of the operator


30


including the steps described hereinabove. The microcontroller


284


may be of a type commercially available, such as a model PIC16C


7


3B available from Microchip Technologies, Inc. The microcontroller


284


is preferably an 8-bit CMOS device including a serial communication port, a random access memory (RAM) and a programmable, read-only memory. The microcontroller


284


is controlled by a suitable oscillator


286


for operation at a clock frequency of 10 MHz.




Microcontroller


284


is connected to a non-volatile memory comprising a serial EEPROM 287 connected to the microcontroller through the serial communication port and is operably connected to a decoder integrated circuit


288


which enables the memory


287


by way of a circuit


290


. Information stored in memory


287


includes information for maximum operator run time timing values and calibration data including indication of the down direction of the door


14


, a door mid-stop time delay value, a braking rate index value, timing data related to the braking function, a door position limit overrun index value, a door operating cycle count, information associated with plural error codes generated by the control system, a door halt timing index value, the total number of safety sensor activated door motion reversals, where applicable, and flags indicating whether the following options are active: a timer controlled closing of the door with a wall control signal, a timer controlled closing of the door with a radio control signal, a timer controlled closing of the door with an auxiliary input signal, a photocell type sensor, a failsafe edge sensor, a normally closed safety input signal and open and close modes initiated by a wall control switch, either momentary or constant contact. The microcontroller


284


may be programmed, for example, to require constant contact or momentary contact of a one button control switch to open and close the door in combination with automatic stop or reverse (opening) of the door when operating in the constant contact mode. The microcontroller


284


is also operable to maintain or save data related to the relationship between the door down position limit switch signal and the braking of the door, and save data and initiate a reversal or opening of the door if operation of the microcontroller is disrupted.




The communication decoder circuit


288


is preferably a commercially available unit as indicated in a correlation table hereinbelow. The decoder


288


is a one of ten type decoder and receives a 4-bit code from the microcontroller


284


and activates an output signal based on the code. The outputs generated by decoder


288


are used to activate a motor drive watchdog circuit, the non-volatile memory


287


, a calibration keypad input circuit and a display driver circuit to be described herein and any options available through a system expansion port. Microcontroller


284


and decoder


288


are connected to a suitable connector


291


via signal conditioning circuits


288




c


for connecting the micro-controller to a serial peripheral interface and for selected external or auxiliary device inputs. The serial peripheral interface is connected to connector


291


at contacts SDI, SDO and SCLK, as indicated. An external diagnostic device or “pod”, not shown, may also be connected to control system


201


at connector


291


.




Referring now to

FIG. 5F

, wall control unit


200


may, alternatively, include momentary push button switches


294


and


296


for controlling the operator


30


to open and close the door


14


, respectively, and a switch


298


for stopping operation of the door. The switches


294


,


296


and


298


are appropriately connected to the control system


201


through a connector


300


and respective signal conditioning circuits


294




a


,


296




a


and


298




a


, respectively.




Output signals from the respective circuits


294




a


,


296




a


and


298




a


are available at schematic references


294




b


,


296




b


and


298




b


, respectively. A door “reverse” input signal may be applied through connector


300


from a suitable door bottom edge sensor, not shown, or obstruction detector, also not shown, which signal is applied through a signal conditioning circuit


302




a


,

FIG. 5F

, to schematic reference


302




b.






Referring again to

FIG. 5D

, references


294




c


,


296




c


,


298




c


and


302




c


are operable to receive suitable signals associated with operation of the push button switches


294


,


296


,


298


and the aforementioned door reversed signal which could be received from a door edge sensor or obstruction detector associated with the door


14


. Controller


284


is also adapted to receive signals by way of references


270




a


and


274




a


from references


270


and


274


,

FIG. 5D

, providing input signals to the controller when the door limit positions have been reached, respectively. An optional motor speed (rpm) input signal may be provided at terminal


273




a


,

FIG. 5D

, to the microcontroller


284


. Microcontroller output references


306


and


308


are operably connected to references


306




a


and


308




a


,

FIG. 5C

, to provide signals to motor drive circuit transistors Q


10


and Q


9


to energize solenoid coils


214




a


and


212




a


, respectively. Interlock solenoid coils


228




a


and


230




a


assure that contact


228


and


230


are in positions to prevent the motor control relays


212


and


214


from being actuated simultaneously when the system is utilizing these relays.




Looking further at

FIGS. 5C and 5E

, the control system


201


includes a control circuit for energizing and de-energizing brake assembly


66


including a connector


320


for supplying 24 volt DC current to the brake assembly. The brake assembly


66


is energized to release by a signal at reference


322


,

FIG. 5D

, output from the microcontroller


284


, which is connected to schematic reference


322




a


,

FIG. 5E

to cause transistor Q


7


to provide current in conductor


324


and to also cause transistor Q


6


to conduct current to the connector


320


. Indicator


326


is operable to illuminate when the brake assembly


66


is receiving current from control system


201


. Motor control relay coils


212




a


and


214




a


and brake assembly


66


will not energize unless a motor control “watchdog” circuit comprising circuit U


7


A is active as will be explained further herein. A brake release feedback signal is also provided at conductor


328


and by way of a signal conditioning circuit


330


,

FIG. 5D

, to signal in terminal no. 2 of microcontroller


284


.





FIG. 5E

also illustrates a connector


332


and signal conditioning circuits


334


and


336


for receiving a radio control signal and a motor speed signal, respectively. Radio control and motor speed signals from circuits


334


and


336


are conducted to microcontroller


284


by way of references


334




a


and


336




a


to references


334




b


and


273




a


on microcontroller


284


, FIG.


5


D.




Referring still further to

FIGS. 5C and 5F

, a motor interlock circuit is provided and may include an external normally closed switch across pins


8


and


9


of connector


300


, or a short connection, as shown, between references


341




a


and


341


. The motor interlock circuit also comprises a hoist interlock including switch


120


connected to connector


344


, a connection between references


346


and


346




a


,

FIG. 5B

, the aforementioned motor thermal interlock and a connection between references


338




a


and


338


. A visual indicator


337


operably connected to reference


338


,

FIG. 5B

, indicates when a switch in the motor interlock circuit has opened to prevent further operation of the motor


48


and any associated fire risk. Still further, a circuit


340


,

FIG. 5C

, includes visual indicators


342


and


343


for the aforementioned hoist interlock and another external interlock, if used, by way of connector


300


, respectively. The hoist interlock, including switch


120


,

FIG. 4

, indicates when the release block


108


is disengaged to allow manual operation of the door operator


30


and thus prevents motor operation during this condition. Power at 24 volts DC is furnished to the interlock circuit


340


by way of references


341


,


341




a


, and the aforementioned external switch or short across connector


300


, see

FIG. 5F

also. Switch contacts of switch


120


are open when the manual drive mechanism of operator unit


30


is operative, thus, removing power from motor control relay coils


212




a


and


214




a


by way of references


346


,

FIG. 5C

, and


346




a


, FIG.


5


B.




Referring to

FIG. 5C

, the aforementioned motor drive watchdog circuit is provided in control system


201


including the NPN transistor Q


8


and monostable multivibrator U


7


A. When signals have been applied to operate motor


48


and release brake assembly


66


, microcontroller


284


provides signal to circuit U


7


A which turns transistor Q


8


“on”. Accordingly, transistor Q


8


enables both the circuits for the motor relay coils


212




a


and


214




a


as well as the brake release circuit to provide a suitable signal by way of connector


320


to energize the brake assembly


66


. However, circuit U


7


A maintains the transistor Q


8


on for a short period of time (milliseconds) and microcontroller


284


is required to send additional activation pulses to circuit U


7


A to maintain the transistor Q


8


in the “on” state. Accordingly, the motor drive watchdog circuit is intended to be a device to minimize unintended brake release or motor energization in the event of failure of the microcontroller


284


, for example.




Referring still further to

FIG. 5C

, a motor drive status feedback circuit is provided including optical coupler U


8


and reference


348


which provides a feedback signal to reference


348




a


,

FIG. 5D

, to provide an input signal to the microcontroller


284


. The drive status feedback circuit protects the microcontroller


284


from harmful transients and is connected in parallel with both of the relay coils


212




a


and


214




a


so that when these coils are energized an “active” signal is provided to microcontroller


284


and one or the other of visual indicators


351




a


or


351




b


is illuminated. If one or the other of the coils


212




a


and


214




a


cannot be energized due to a failure of the motor watchdog circuit, microcontroller


284


is operable to not provide output signals after a suitable time delay. If coils


212




a


or


214




a


cannot be energized due to one or more of the motor drive interlock inputs, an inactive or lack of signal is provided to the microcontroller


284


. Under these conditions the microcontroller


284


is operable to not provide drive output signals to the coils


212




a


or


214




a


. Brake assembly


66


will be caused to reengage, after a suitable time delay, and proper error codes will be shown on a display to be explained in further detail herein. Still further, if the motor drive feedback circuit provides an “active” signal to microcontroller


284


when it should be “inactive” the microcontroller will store and display proper error codes and attempt to shut down the erroneous control outputs. Failing to correct such a situation, the microcontroller


284


will store the proper error code and then initiate an emergency shutdown by turning “on” transistor Q


11


, FIG.


5


D. With transistor Q


11


turned on a signal is provided via references


393


and


261


, see

FIG. 5A

also, to SCR


262


to short circuit the 24 VDC power supply circuit and cause fuse


256


to open.




Referring now to

FIG. 5D

,


5


F and


5


G, the communications decoder circuit


288


, as previously mentioned, is operable to provide output signals used to activate the motor drive watchdog circuit and a calibration keypad input circuit including a parallel-to-serial data converter circuit U


3


,

FIG. 5F

, by way of conductors


360


and


362


. Data converter circuit U


3


also communicates with microcontroller


284


by way of conductors


363


and


365


. Data converter circuit U


3


is connected to a keypad


366


, including eight calibration keys for providing input to the microcontroller


284


by way of the data converter circuit. As shown in

FIG. 5F

, a CAL MODE key is used to enter and exit the control system calibration mode. The OPEN key is used to provide the same function as a signal at reference


294




c


. The CLOSE key is used to provide the same function as a signal at the close input reference


296




c


, except this key will not override an active reverse input signal to the microcontroller


284


. The STOP key of keypad


366


provides the same function as a signal input at connector or flag


298




c


. The OPEN and CLOSE mode keys provide the open mode of operation of the control system


201


and the close mode of operation. A SCROLL key allows scrolling through the available calibration functions and a SET/CLEAR key sets or clears the highlighted calibration function. Decoder


288


enables a display driver circuit U


1


,

FIG. 5G

, by way of conductor


368


. Simultaneously, microcontroller


284


provides data and clock signals via conductors


366


and


367


. Display driver U


1


is connected to a digital display circuit


370


,

FIG. 5G

, disposed within housing


50


and viewable upon removing housing cover


50




c


during calibration or trouble shooting the control system.




The calibration mode of control system


201


described and shown is accessible when microcontroller


284


is waiting for a valid command. Activating and holding the CAL MODE key under these circumstances for a short period of time will effect operation of the microcontroller


284


to enter the calibration mode. The seven segment LED display will go blank and appropriate open and close mode indicators may be illuminated indicating a currently selected mode of operation. Any indicators associated with any previously selected calibration functions will also illuminate and a currently active calibration function indicator will blink. Activation of the open and close mode keys will cause the next indicator in the associated row to be highlighted indicating that this mode of operation is currently selected. Successive key depressions will repeat this operation, and will revert to the first mode of operation if no other options are available.




The SCROLL key will cause the next calibration function to be active and will illuminate an appropriate indicator in a blinking mode. Successive depressions of the SCROLL key will repeat this operation or will revert to the first function if no further options are available. The SET/CLEAR key will cause the active calibration function to be set or enabled if the function is not already set or enabled. However, when a limit overrun function is selected the 7-segment display


370


will illuminate indicating a current limit overrun index value and successive depressions of the SET/CLEAR key will increment this value from zero to nine, then roll over to zero again. A value of zero represents no limit overrun or an immediate stop when a corresponding limit switch signal is provided to the microcontroller. The values of one through nine of the limit overrun index value indicates progressively longer time delays between receipt of a limit signal from limit switch unit


264


and onset of braking procedure. A value of nine equates to approximately 540 milliseconds of time delay before onset of braking.




Braking rate or effecting operation of the brake assembly


66


to brake rotation of the motor output shaft, may be controlled and the seven segment display


370


will indicate a current braking rate index value. Successive depressions of the SET/CLEAR key will increment the value from zero to nine and then roll over to zero again. A value of zero represents no progressive braking and brake forces are applied in full immediately on timing out of the limit overrun in the given direction of door travel. A value of nine represents a minimum braking rate possible and provides the smoothest stop but the greatest amount of “coasting” of the door after receiving a limit signal and any appropriate limit overrun time delay.




The microcontroller


284


provides a nominal 24VDC signal by way of transistor Q


6


to release the brake assembly


66


. Nominal brake operation is achieved by the microcontroller


284


effecting release or energizing the brake with the 24VDC signal for a period of 250 milliseconds. This signal is pulse width modulated by applying a 24 VDC square wave signal at a rate of approximately 5 KHz with a duty cycle of approximately 50%. This operation continues until the microcontroller


284


initiates the braking procedure. During the braking procedure, the pulse width modulation frequency is reduced to 8 Hz and the duty cycle is reduced to a user selected value of between approximately 2% and 18%. Alternatively, immediate braking may be selected during the calibration mode. In this procedure the brake energizing or release signal is turned off immediately with no pulse width modulation. The purpose of the pulse width modulated braking procedure or progressive braking is to provide a smooth stop of the door


14


, eliminate shock forces on the operator unit


30


, reduce door operation sound level and enhance door life. At the end of the braking procedure the brake energization signal remains turned off and the microcontroller


284


enters a so called halt mode. The braking procedure may also be modified by continuing the 5 KHz pulse width modulation frequency and then the duty cycle is reduced in preset steps at time intervals set by the user in the calibration mode. The duty cycle is reduced over time to zero percent.




In another preferred operating method, brake release is initiated by applying the 24VDC signal to the brake assembly


66


at a pulse width modulation frequency of about 5 KHz and an initial duty cycle of zero percent. This duty cycle is then increased in preset steps at a preset time interval. The time interval may be selected in the calibration mode and the duty cycle will increase to one hundred percent and remain there for 250 milliseconds. Then the duty cycle will be set to fifty percent. The purpose of such a procedure is to minimize shock loads experienced at the initiation of door movement and provide a smooth start which reduces door operation sound level and enhances door life. The above-mentioned pulse width modulation frequencies, duty cycles and time intervals may be selected in accordance with the particular motor, operator unit configuration and door configuration.




The control system


201


may also be provided with a mid-stop setting whereby the microcontroller


284


may be programmed to set a time delay associated with a mid-stop limit position. The mid-stop limit position of the door


14


is a preselected position of the bottom edge of the door in the upward or opening travel mode of the door at which the operator unit


30


will stop before reaching the “up” limit position sensed by limit switch unit


264


. Thus, activating the control system


201


to open or move the door


14


to the up position when the door is at the down limit position will cause the door


14


to move up until the mid-stop time limit has elapsed. The microcontroller


284


will then effect shutoff of motor


48


to stop the door in the mid-stop position.




Activation of the up or open switch


294


or the OPEN key on keypad


366


, when the door is in the mid-stop position, will cause the door to open until it reaches the up limit as determined by limit switch unit


264


. In this way, particularly long or high doors may be partially opened when the entire door travel is not required. Setting the mid-stop limit using the calibration keypad


366


may be carried out by actuating the RUN UP or OPEN switch or key on the keypad when the door is at the down or closed limit position. The door


14


will then begin to open and a mid-stop timing function will begin counting. When the door has reached the desired level for the mid-stop position, the door is stopped by actuating either the stop switch


298


or the STOP key on keypad


366


. The controller


284


will store the mid-stop timer value when the SET/CLEAR key is activated. Once the mid-stop position has been set, SET/CLEAR key actuations will clear the mid-stop timer and deselect that function. When the mid-stop timer function is deselected, further actuations of the SET/CLEAR key have no effect. The mid-stop timing function will not be set as described above if door “run-up” was not initiated from the down limit position of the door.




The control system


201


described and shown may also provide a maximum run timing function. This function may be cleared by actuating the SET/CLEAR key of keypad


366


to clear any maximum run timing value stored in the memory


287


. The maximum run timing function is operable for both directions of travel thanks to the provision of two separate maximum run timers in microcontroller


284


. If the operator unit


30


does not achieve the appropriate limit position to actuate either the up limit or down limit of the switch unit


264


then the time interval specified will cause the operator unit to shut off. If the operator unit


30


was operating in the door down or closing direction, it will also reverse the direction of movement of the door


14


and operate until the up limit position is achieved. The time value for the maximum run timing function in both the up and down mode is measured during a first complete run from each limit position to the opposing limit position and this time value is increased by adding a predetermined number of time intervals (seconds) or by adding a fixed percentage of the measured time (i.e., 10%). This resulting time interval is stored in memory


287


for each direction of travel and can only be cleared within the calibration mode as described above.




After an event of the operator unit


30


exceeding the maximum run time in either the up or down operating mode, an appropriate error code is stored and displayed by the display


370


. Moreover, after a maximum run time has been exceeded, the microcontroller


284


will effect shutdown of the operator unit


30


and will require reset by removal and subsequent reapplication of power to the control system


201


.




The control system


201


described and shown is also provided with a code recall function whereby the display


370


will, when this function is selected during the calibration mode, display the most recent error code stored in memory


287


. Actuating the SET/CLEAR key of keypad


366


will cause the previous error code to be displayed. This process can be continued until all stored error codes have been displayed. The display


370


continually displays a condition code in the operating mode of the system and displays calibration information in the calibration mode. A specific code is assigned to each condition that the user enters into the system.




The control system


201


previously described will now be summarized. Those skilled in the art will appreciate that the microcontroller


284


may be programmed by one of skill in the art to perform the functions described and employing the circuitry described and illustrated in

FIGS. 5A through 5G

. A correlation table for substantially all of the circuit elements shown in the diagram of

FIGS. 5A through 5G

follows herein. The modular design of the control system


201


shown and described is advantageous and virtually all connections made in the assembly process may be accomplished by way of the plug-in connectors illustrated and described. The connections may enter the housing


50


through a cable entry port, not shown, adapted to restrain the cabling and permit the cable connections to be substantially sealed.




Moreover, the control system


201


shown and described may be remotely mounted from the operator unit


30


for installations wherein the size and location of the housing


50


presents a clearance problem. For example, all of the components of the control system


201


shown in

FIGS. 5A through 5G

, may be mounted within the housing


50


and the housing


50


remotely mounted from the operator unit


30


whereby appropriate cabling may be provided for conducting signals between the operator unit and the control system


201


by way of one of the four connectors


202


,


204


,


206


or


208


, and connectors


266


,


320


and


344


. In this way the control system


201


, shown in

FIGS. 5A through 5G

, may be located in virtually any desired position remote from the operator unit


30


. As mentioned previously, the range of applications of the control system for controlling an operator, such as the operator unit


30


, is enhanced by the arrangement of the motor power conductor and control conductor connectors and contactor arrangements, as illustrated in

FIG. 5B

, and which is provided as part of a single board or control unit substrate which may be mounted in the housing


50


.




Accordingly, as previously mentioned, the housing


50


may be disconnected from the remainder of the operator unit shown in

FIGS. 2 and 3

, for example, and mounted at a remote site. Each of the connectors


266


,


320


and


344


, as well as the selected one of the four connectors


202


,


204


,


206


or


208


is of a configuration unlike any of the other connectors. Thus, an intermediate section of bundled cable, for example, with appropriate connector members at each end may be interposed the housing


50


and the remainder of the operator unit and connections made to the motor


48


via one of connectors


202


,


204


,


206


or


208


, the limit indicators or switch unit


264


on the operator unit


30


via the connector


266


, the brake assembly


66


via the connector


320


and the hoist interlock switch


120


on the operator unit via the connector


344


. Since each of these connectors is of a different configuration, the chances of an improper connection between the control system


201


and the motor and other components described above is substantially eliminated. Suitable cable entry ports may be provided in the housing


50


, not shown, to provide for interconnection between the control system


201


and the hoist interlock, the limit indicators, the motor


48


and the brake assembly


66


.




The control system


201


is advantageously protected against power supply transient signals conditions by the circuitry illustrated in FIG.


5


A and including the voltage overprotection circuit. The 24 VDC power supply circuit and 5 VDC power supply circuit for controlling the logic circuits is advantageously arranged as shown in FIG.


5


A.




The wall-mounted control unit or box


200


is advantageously provided with the one button input type switch


278


, alone or together with the push button switches


294


,


296


and


298


. Each switch will cause the operator unit


30


to be controlled to open or close the door


14


from a momentary activation. Alternatively, the microcontroller


284


may be programmed through the calibration input keypad


366


, as described, to require constant contact or engagement of the switches


278


,


294


,


296


. The microcontroller


284


is programmable to operate such that if the switch


296


to close the door or the CLOSE key of keypad


366


is engaged when in the constant contact mode and then released, the operator unit


30


will reverse direction and run the door


14


to the “oup” limit position. If switch


278


is utilized, this switch may operate in the constant contact or momentary contact mode of operation and a stop input signal or a keypad signal causes a moving door to stop by deenergizing the motor


48


and beginning the braking procedure immediately. Control signals may be transmitted to the control system


201


by way of the circuit


334


from a remote radio transmitter. However, control signals from a remote radio transmitter may be initiated only by momentary contact of a control switch on the transmitter to perform the same functions as the switch


278


performs when operating in the momentary contact mode.




Further, the microcontroller


284


is programmable to operate in such a manner that when the switch


296


is actuated, such action can override a door reverse input signal if the switch remains engaged until the door reaches the down limit position as sensed by the limit switch unit


264


. In this way, a defective door bottom edge sensor or obstruction detector may be overridden.




Still further, the microcontroller


284


is programmable to enter the so-called halt mode during which the microcontroller will not respond to any commands. The halt mode may be run for a preset period of time such as approximately 0.25 seconds to 5.0 seconds. This halt timer interval may be set with the microcontroller


284


in the calibration mode, if desired. After the halt mode time delay has elapsed, the microcontroller


284


is then operable to accept another command. One purpose of the halt mode is to reduce shock loads experienced by the operator unit


30


during door operation such as in rapid reversal of the direction of movement of the door.




The microcontroller


284


is also programmed to deenergize motor


48


and apply brake


66


to the motor output shaft immediately upon receipt of a signal at reference


302




c


and the associated circuit


302




a


which is operable to receive a signal from an external safety device, such as a door bottom edge sensor and/or an obstruction detector, or other controllers or devices, not shown. Upon receipt of a signal from circuit


302




a


, the microcontroller enters the halt mode and after lapse of the halt mode time delay, the motor


48


is energized to move the door


14


to the up or open limit position or other defined limit or safety position. Moreover, an active signal from circuit


302




a


will not permit the controller to operate the motor


48


to close the door unless overridden, as mentioned previously.




The motor interlock circuits will prevent operation of the operator unit


30


without any intervention from the microcontroller


284


. However, in order to perform error diagnosis, the indicators


337


,


342


and


343


will advise an operator if one of the interlocks has refused to allow the motor


48


to operate. In this regard also, an indicator


335




a


,

FIG. 5F

, is provided to indicate when 24 VDC power is being furnished to the control system


201


.




The control system


201


is advantageously provided with a radio control input signal circuit as previously described and shown on FIG.


5


F. Connector


332


is adapted to be connected to a radio receiver, not shown, and to receive a signal at circuit


334


to operate the microcontroller


284


in the same manner that the one button switch


278


may sequentially operate the controller to move the door


14


between open and closed positions. The circuit of the control system


201


illustrated in

FIGS. 5A through 5G

also advantageously includes a 24 VDC power supply available through the connector


332


to power the aforementioned radio receiver. Connector


332


is also available to receive a motor speed signal from a suitable motor speed sensor, not shown, which preferably would be a nominal square wave signal with a frequency directly proportional to the rotational speed of the motor output shaft for the motor


48


or the output shaft


34


of the operator unit


30


. An “rpm” or speed signal may be used to detect a stalled motor, a broken drive train, unintentional door movement, output shaft overspeed or contact between the door and an obstacle in its path, for example.




Preferred modes of operating the brake assembly


66


to release and allow rotation of the motor output shaft


48


and to progressively brake operation of the operator unit


30


have been previously described. Moreover, the brake operating feedback signal provided via conductor


328


and the signal conditioning circuit


330


is advantageous to permit the microcontroller


284


to indicate an appropriate error code and also initiate an emergency shutdown of the control system by outputting an appropriate signal via controller pin RB


7


,

FIG. 5D

, and transistor Q


11


which provides a signal at schematic reference


393


, which in turn, provides a signal to the over-voltage sensing circuit


260


by way of schematic reference


261


,

FIG. 5A

, to effect opening of fuse


256


. This action removes all power from control system


201


, motor


48


and brake assembly


66


and applies brake assembly


66


to stop rotation of shaft


34


. An output signal on pin RB


7


of microcontroller


284


may also be provided during other emergency shutdown conditions described above to effect the same action just described with regard to opening fuse


256


.




Another advantageous feature of the control system


201


is the motor interlock circuit and motor watchdog circuit illustrated in

FIG. 5C

will turn on transistor Q


8


if an appropriate signal is provided to the one shot multi-vibrator U


7


A from microcontroller


284


by way of decoder


288


at references


288




d


-


288




e.


Transistor Q


8


when turned “on” will, in turn, allow transistors Q


9


or Q


10


, depending on which has been furnished a signal by way of references


308




a


and


306




a


from the microcontroller


284


. Transistors Q


6


and Q


7


are also allowed to turn on via a signal on conductor


324


. Transistor Q


8


is turned on for intervals of eleven milliseconds by the microcontroller


284


operating through the decoder circuit


288


. If the signal is not continuously furnished through the mono-stable multi-vibrator U


7


A, transistor Q


8


will turn off thereby turning off transistors Q


9


or Q


10


and Q


6


and Q


7


deenergizing motor


48


by deenergizing either the relay actuator


212




a


or


214




a


and brake assembly


66


via the circuit shown in FIG.


5


E. Moreover, the interlock relays


228


,


228




a


and


230


,


230




a


insure that the motor control relays cannot be energized at the same time. If the microcontroller


284


has given a proper command to energize motor


48


in one direction or the other and the proper voltage is not applied across the relay coils


212




a


or


214




a


, then an inactive signal is present at reference


348


, the microcontroller


284


will initiate a braking procedure and display and store appropriate error codes. This action will also take place if watchdog circuit, including circuit U


7


A, or transistors Q


9


or Q


10


, is not operating properly or if motor interlock circuits are open.




The operation of the control system


201


shown in

FIGS. 5A through 5G

and described herein is believed to be understandable to those of skill in the art from the foregoing description. Moreover, the construction of the control circuit is also believed to be understandable to those of skill in the art based on the description, the drawing illustrations and the following correlation table. This is a correlation table of alphanumeric designations shown in the drawings hereof, their descriptions, and examples of commercially available components designated.





















Manufacturer's






Designation




Description




Manufacturer




P/N











C1, 3-6, 10,




Capacitor,








11, 22




.1uF 50V Mono






C8




Capacitor,







3300uF, 50v







electrolytic






C12




Capacitor,







.33uF 50V







Mono






C2, 13, 14,




Capacitor,






16-18, 24, 32,




.01uF 50V






58, 60, 62, 73




Disk






C23




Capacitor,







.033uF Film






C26-C30




Capacitor,







.01uF,






C46, 47, 50,




Capacitor,






51, 53, 55,




.001uF 50V






57, 59, 61, 71




Disk






C68, 69




Capacitor,







.001uF 500V







Disk






C7, 15, 19-21,




Capacitor,






25, 31, 41,




.01uF 500V






45, 48, 49,




Disk






52, 54, 56,






65, 66, 70






C9




Capacitor,







22uF 50V







Elec






D1




Display, 7-




Kingbrite




SC05-11HWA







segment






D22-25




Diode, 1N5402




GI






D26-34, 44




Diode, 1N4002






D3-21, 35-39,




LED, T1,




Kingbrite




L132XGD-TGC






42, 43




Green






F1




Fuse




Bussman




AGC-2






F1, 2




Fuse Clip




Keystone




3513






F2




Fuse




Bussman




AGC-3/10







Jumper




Buchanan




J74






J1




Header, 13-




Amp




1-103639-2







pin







.1 spaced






J11




Header, 3-pin




Amp




644753-3







SL-156






J2




Terminal




Buchanan




SSB7FM030202







block,







barrier type,







3-pole






J3




Header, 5-pin




Amp




640900-1







Multimate






J4




Header, 4-pin




Amp




644753-4







SL-156






J5




Terminal




Buchanan




6PCV09







block,







9-pole






J6, 12




Header, 12-




Amp




350713-1*







pin Multimate






J7




Header, 7-pin




Amp




644753-7







SL-156






J8




Header, 2-pin




Amp




644753-2







SL-156






J9, 10




Header, 12-




Amp




350713-1*







pin Multimate






K1, 3




Relay, power




Song Chuan




735-3A-CT-









24VDC (73572)






K2, 4




Relay,







interlock






MOV1-4




MOV




Maida




D6521ZOV350RA3









5






MOV5-10




MOV




Maida




D65ZOV681RA260






Q1, 3-5, 7-12




Transistor,




Samsung







MPSA05






Q13




Transistor,




Samsung







MPSA55






Q2




Transistor,




Motorola,







TIP47 or TIP50




et al.






Q6




Transistor,




Motorola,







TIP107




et al.






R1, 17, 75,




Resistor, 1.2K




SEI






91, 92




1/4W 5%






R80-R84




Resistor







100 ohms






R104




Resistor, 3.3K




SEI







1/4W 5%






R105, 106




Resistor, 0




SEI




CD1/4 ZERO TR







1/4W






R107




Resistor, 1.5K




SEI







1/4W 5%






R14




Resistor, 2.2K




SEI







1/4W 5%






R16, 53-55,




Resistor, 22K




SEI






60, 70, 72, 87




1/4W 5%






R18, 58, 76-79




Resistor, 5.1K




SEI







1/2W Mini 5%






R19-26, 28,




Resistor, 4.7K




SEI






37, 39, 42,




1/4W 5%






43, 46, 47,






50, 51, 56,






61, 86, 89,






96-103






R2, 13, 15




Resistor, 1K




SEI







1/4W 5%






R27




Resistor, 1K




SEI







1/2W 5%






R29-35, 63,




Resistor, 10K




SEI






67, 74, 93




1/4W 5%






R3-12




Resistor, 220




SEI







1/4W 5%






R36, 38, 40,




Resistor, 7.5K




SEI






57




1/4W 5%






R41, 45, 49,




Resistor, 8.2K




SEI






88




1/4W 5%






R44, 48, 52,




Resistor, 3.9K




SEI






90




1/2W 5%






R59




Resistor, 750




SEI







1/4W 5%






R62




Resistor, 560




SEI







3W Mini 5%






R64




Resistor, 18K




SEI







1/4W 5%






R65




Resistor, 100K




SEI







1/4W 5%






R66, 69, 71,




Resistor, 240




SEI






94




1/4W 5%






R68




Resistor, 470K




SEI







1/4W 5%






R73




Resistor, 1.8K




SEI







1/4W 5%






R85




Resistor, 3.9K




SEI







1/4W 5%






R95




Resistor, 5.6




Ohmite




OX56GK







1W 10%






SC1




SCR, MCR12N




Motorola,








et al.






U1




IC, MC14489P




Motorola






U2




IC, 74HC42




Harris, et al.






U3




IC, 74HC589




Fairchild,








et al.






U4




IC, 93LC46B-







I/P






U5




PIC16C73B-20




Microchip







I/SP






U6




Voltage




Motorola,




MC7805BT







Regulator,




et al.







7805BT






U7




IC,




Motorola







74HC4538AN




et al.






U8




Opto coupler,




Lite-on







LTV4N37






Y1




Ceramic




U.S.




ZTT10.00MTA







Resonator,




Electronics







10 MHz






Z1-12, 15-21,




Diode, Zener,






23




1N5231B






Z13, 22, 25-29




Transzorb,




HTA, GI







P6KE47






Z14




Diode, Zener,







1N5252B






Z24




Diode, Zener,




Motorola







1N5261B














Although preferred embodiments of the invention have been described in detail, those skilled in the art will recognize that various substitutions and modifications may be made without departing from the scope and spirit of the appended claims.



Claims
  • 1. A control system for controlling the operation of a door operator unit to move a door between open and closed positions, said operator unit including a reversible electric drive motor, a drive unit interconnecting said motor with a door, and an electrically operated brake unit operably connected to said drive motor and said drive unit for braking rotation of an output shaft of said drive unit, said control system comprising:a programmable microcontroller operable to provide door open, door close and door stop output control signals; a motor power supply control circuit for operating said drive motor in reverse directions of rotation; a motor drive circuit including motor relay actuator means, said motor drive circuit being adapted to receive control signals from said microcontroller to effect operation of said drive motor through said motor power supply control circuit to provide for one of opening and closing said door; and a brake control circuit operably connected to said microcontroller and operable to effect releasing said brake unit and provide a repeated pulse signal to said brake unit for progressively braking rotation of said output shaft.
  • 2. The control system set forth in claim 1 wherein:said brake control circuit is operably connected to said motor drive circuit for releasing said brake substantially simultaneously with energizing said drive motor through said motor drive circuit.
  • 3. The control system set forth in claim 1 including:a brake release feedback circuit operably connected between said brake control circuit and said microcontroller for providing a brake status feedback signal to said microcontroller.
  • 4. The control system set forth in claim 1 including:door position limit indicator means for indicating when said door has reached an open position and a closed position, respectively, circuit means connected to said door position limit indicator means and said microcontroller for providing input signals to said microcontroller to indicate when said door has reached an open limit position and a closed limit position, respectively.
  • 5. The control system set forth in claim 1 including:a power supply circuit for said control system including connector means for connecting said control system to a power source, a converter circuit for converting AC line voltage to low voltage DC power and a voltage sensing circuit operably connected to said power supply circuit and operable to effect interruption of power to said control system.
  • 6. The control system set forth in claim 5 including:an emergency shutdown circuit interconnected between said voltage sensing circuit and said micro-controller and operable upon receiving an output signal from said microcontroller to effect operation of said voltage sensing circuit to effect interruption of power to said control system.
  • 7. The control system set forth in claim 1 including:a door reverse control circuit adapted to be connected to a device for providing a signal to effect reversing the direction of movement of said door when said door is moving toward a closed position, said reverse control circuit being operable to provide an input signal to said microcontroller to effect operation of said operator unit to stop movement of said door toward a closed position and effect operation of said operator unit to move said door to an open position.
  • 8. The control system set forth in claim 1 including:a keypad operably connected to said microcontroller and to a decoder circuit by way of a keypad driver circuit for providing calibration of a selected function controlled by said microcontroller including at least one of a door limit position overrun time delay, a progressive braking rate for applying braking action by said brake unit to stop rotation of said output shaft, a mid-stop setting for arresting movement of said door between its open and closed positions, a maximum run time of said operator unit and deenergizing said drive motor for a predetermined time commencing with deenergization of said drive motor.
  • 9. The control system set forth in claim 8 wherein:said control system is mounted in an enclosure and is operably connected to said motor, said drive unit and said brake unit by connector means whereby said enclosure may be selectively mounted on said operator unit and remote from said operator unit.
  • 10. A control system for controlling the operation of a door operator unit to move a door between open and closed positions, said operator unit including a reversible electric drive motor, and a drive unit interconnecting said motor with a door, said control system comprising:a programmable microcontroller operable to receive control signals from at least one of plural switches for providing door open, door close and door stop signals, and a single switch for sequentially providing door open, door close and door stop signals; a motor power supply control circuit for operating said drive motor in reverse directions of rotation; a motor drive circuit including motor relay actuator means, said motor drive circuit being adapted to receive control signals from said microcontroller to effect operation of said drive motor through said motor power supply control circuit to provide for one of opening and closing said door; an electrically operated brake connected to said drive unit for braking rotation of an output shaft of said drive unit; a brake control circuit operably connected to said microcontroller and said brake for releasing said brake; and a motor watchdog circuit operably connected to said motor drive circuit and including a switch connected to said motor drive circuit and said brake control circuit and to means for receiving a signal from said microcontroller, said means being operable in response to the absence of a predetermined signal from said microcontroller to effect shutdown of said drive motor and engagement of said brake in response to a malfunction of said control system.
  • 11. The control system set forth in claim 10 including:a brake release feedback circuit operably connected between said brake control circuit and said microcontroller for providing a brake status feedback signal to said microcontroller.
  • 12. The control system set forth in claim 10 including:a power supply circuit for said control system including connector means for connecting said control system to a power source, a converter circuit for converting AC line voltage to low voltage DC power and a voltage sensing circuit operably connected to said power supply circuit and operable to effect interruption of power to said control system.
  • 13. The control system set forth in claim 12 including:an emergency shutdown circuit interconnected between said voltage sensing circuit and said micro-controller and operable upon receiving an output signal from said microcontroller to effect operation of said voltage sensing circuit to effect interruption of power to said control system.
  • 14. A control system for controlling the operation of a door operator unit to move a door between open and closed positions, said operator unit including a reversible electric drive motor, a drive unit interconnecting said motor with a door, and an electrically operated brake operably connected to said drive motor and said drive unit for braking rotation of an output shaft of said drive unit, said control system comprising:a programmable microcontroller operable to receive door open, door close and door stop signals and to provide control signals to a motor drive circuit; a motor power supply control circuit for operating said drive motor in reverse directions of rotation; a motor drive circuit adapted to receive control signals from said microcontroller to effect operation of said drive motor through said motor power supply control circuit to provide for one of opening and closing said door; a brake control circuit operably connected to said microcontroller and operable to control engagement and release of said brake; and a keypad operably connected to said microcontroller including a calibration mode key and plural keys for operating said control system to cause said operator unit to open said door, close said door and stop operation of said operator unit, respectively, said plural keys being operable in response to actuation of said calibration mode key in a calibrate mode of said microcontroller for providing calibration of a selected function controlled by said microcontroller including at least one of a door limit position overrun time delay, a progressive braking rate for applying braking action by said brake to stop rotation of said output shaft, a mid-stop setting for arresting movement of said door between its open and closed positions, a maximum run time of said operator unit and deenergizing said drive motor for a predetermined time commencing with deenergization of said drive motor.
  • 15. The control system set forth in claim 14 including:a visual display operably connected to said microcontroller for displaying a selected condition code in an operating mode of said control system and calibration information when said control system is in a calibration mode.
  • 16. The control system set forth in claim 15 including:a memory operably connected to said microcontroller and operable to store signals related to multiple error codes for recall and display on said visual display.
  • 17. The control system set forth in claim 14 wherein:said microcontroller includes timer means for automatically setting said maximum run time of said operator unit between said open and closed positions based on a measured run time of said door between said open and closed positions plus an additional increment of time.
  • 18. The control system set forth in claim 14 including:a connector for connecting a device to said control system to retrieve data stored in a memory operably connected to said microcontroller and to at least one of perform specific tests and monitor functions related to the operation of said control system.
  • 19. In a control system for controlling the operation of a door operator unit to move a door between open and closed positions, said operator unit including a reversible electric drive motor, a drive unit interconnecting said motor with a door, an electrically operated brake operably connected to said motor and said drive unit for braking rotation of an output shaft of said drive unit, and door position indicator means associated with said operator unit, said control system comprising a motor power supply control circuit, a programmable microcontroller operable to receive door open, door close and door stop signals and to provide control signals to a motor drive circuit, and a brake control circuit, the improvement comprising:a housing adapted to be detachably connected to said operator unit and including said microcontroller, said motor power supply control circuit and said brake control circuit and plural connectors disposed in said housing for interconnecting said operator unit with said control system and adapted to provide for mounting said housing at a location remote from said operator unit while remaining operably connected to said operator unit through conductor means extending between said housing and said motor, said indicator means and said brake.
  • 20. The invention set forth in claim 19 wherein:said power supply control circuit includes a plurality of relay contactors adapted to be connected to a source of electric power at selected voltages and plural connectors connected to said power supply control circuit for connecting said control system to said motor depending on a voltage and phase requirement for driving said motor.
  • 21. A method for controlling the operation of a door operator unit to move a door between open and closed positions, said operator unit including a reversible electric drive motor, a drive unit interconnecting said motor with a door and an electrically operated brake operably connected to said drive unit for braking rotation of an output shaft of said drive unit, said control system including a programmable microcontroller operably connected to means for providing door position limit signals to said microcontroller, said method comprising the steps of:moving said door toward one of an open and closed limit position by energizing said motor and releasing said brake; and upon said door approaching one of said open and closed position, deenergizing said motor at a selected overrun time delay after receiving a door limit position signal by said microcontroller.
  • 22. The method set forth in claim 21 including the step of:providing a calibration circuit operably connected to said microcontroller; and selecting a value of overrun time delay by way of said calibration circuit to provide a selected time delay between receipt of a limit position signal by said micro-controller and onset of applying a signal to effect operation of said brake to brake rotation of said output shaft.
  • 23. The method set forth in claim 22 including the step of:preventing said door from moving toward an open position during said period of over run time delay and during operation of said brake when said door is approaching said closed position.
  • 24. The method set forth in claim 21 including the step of:initiating a braking procedure with said brake in response to a door limit position signal received by said microcontroller.
  • 25. The method set forth in claim 23 wherein:said braking procedure comprises deenergizing a brake operator of said brake to provide braking of said output shaft by applying a pulse width modulated signal to said brake operator, and progressively reducing a duty cycle of said modulated signal applied to said brake operator to halt rotation of said output shaft.
  • 26. The method set forth in claim 25 including the step of:providing a signal to said brake operator from a predetermined set of braking rate signals stored in said microcontroller by selecting one of said braking rate signals at will.
  • 27. The method set forth in claim 21 including the step of:causing said microcontroller to effect arresting movement of said door in a position between an open limit position and a closed limit position after a predetermined time which commences with movement of said door from one of said limit positions toward the other of said limit positions.
  • 28. The method set forth in claim 27 wherein:said control system is operated to cause said door to stop in a position between said limit positions after a predetermined time commencing with movement of said door from a closed limit position of said door.
  • 29. The method set forth in claim 21 including the step of:causing said microcontroller to effect shutoff of said motor after a predetermined time commencing with movement of said door away from one of said open and closed limit positions.
  • 30. The method set forth in claim 21 including the step of:causing said microcontroller to not respond to a signal to effect one of opening and closing said door for a predetermined time commencing with deenergization of said motor to halt movement of said door.
  • 31. A method for controlling the operation of a door operator unit to move a door between open and closed positions, said operator unit including a reversible electric drive motor, a drive unit interconnecting said motor with a door, an electrically operated brake operably connected to said drive unit for braking rotation of an output shaft of said drive unit, and a control system including a programmable microcontroller operably connected to means for providing door position limit signals to said microcontroller, said method comprising the steps of:moving said door toward one of an open and closed limit position by energizing said motor and releasing said brake; and upon said door approaching one of said open and closed position, causing a brake operator of said brake to progressively brake rotation of said output shaft by applying a pulse width modulated control signal to said brake operator.
  • 32. The method set forth in claim 31 including the steps of:reducing a duty cycle of said modulated signal applied to said brake operator in preset steps at selected time intervals to halt rotation of said output shaft.
  • 33. The method set forth in claim 31 including the step of:providing a calibration circuit operably connected to said microcontroller; and selecting values of duty cycle and time interval by way of said calibration circuit to effect operation of said brake.
  • 34. A method for controlling the operation of a door operator unit to move a door between open and closed positions, said operator unit including a reversible electric drive motor, a drive unit interconnecting said motor with a door, an electrically operated brake operably connected to said drive unit for braking rotation of an output shaft of said drive unit, and a control system including a programmable microcontroller operably connected to means for providing door position limit signals to said microcontroller, said method comprising the steps of:moving said door toward one of an open and closed limit position by energizing said motor and releasing said brake; causing said microcontroller to deenergize said motor and effect arresting movement of said door in a position between an open limit position and a closed limit position after expiration of a first predetermined time which is automatically set by said microcontroller and commences with movement of said door from one of said limit positions toward the other of said limit positions; and causing said microcontroller to not respond to a signal to effect one of opening and closing said door for a predetermined time commencing with deenergization of said motor to arrest movement of said door.
  • 35. The method set forth in claim 34 wherein:said control system is operated to cause said door to stop in a position between said limit positions after said first predetermined time commencing with movement of said door from a closed limit position of said door.
  • 36. The method set forth in claim 34 including the step of:determining said first predetermined time by measuring a second time period which comprises the time required to move said door between said open and closed positions and adding a third predetermined time period to said second time period to provide said first predetermined time.
  • 37. A method for controlling the operation of a door operator unit to move a door between open and closed positions, said operator unit including a reversible electric drive motor having a rotatable output shaft, a drive unit including an electrically actuated brake interconnecting said motor with a door and a control system including a programmable microcontroller including a memory, a keypad including plural keys for providing information to said microcontroller and a visual display for displaying a condition code and calibration information associated with operation of said operator unit, said method including the step of:actuating selected keys of said keypad to select a door open mode of operation, a door close mode of operation, a calibration mode and calibration functions, respectively, including at least one predetermined value of braking rate of said brake.
  • 38. The method set forth in claim 37 including the steps of:providing said operator unit with a control switch for providing a signal to said control system to energize said motor and deenergize said motor; and using said keypad to cause said control system to require one of constant contact of said switch and momentary contact of said switch, respectively.
  • 39. The method set forth in claim 37 including the step of:causing said visual display to display selected error codes associated with a fault condition of said operator unit and said control system, respectively.
  • 40. The method set forth in claim 37 including the step of:using said keypad to enter a value of time delay between said door reaching a one of said positions and onset of a braking procedure for arresting operation of said operator unit.
  • 41. The method set forth in claim 37 including the step of:using said keypad to select a time delay associated with a midstop limit position of said door between said open and closed positions.
  • 42. The method set forth in claim 37 including the step of:using said keypad to clear a maximum run time of said motor.
  • 43. The method set forth in claim 37 including the steps of:using said keypad and said visual display to select a direction of rotation of said output shaft equivalent to a given direction of travel of said door.
  • 44. The method set forth in claim 37 including the steps of:using said keypad to select at least one of a direction of output shaft rotation of said operator unit corresponding to a given direction of door travel and controlling direction sensitive input commands to said control system.
  • 45. A method for controlling the operation of a door operator unit to move a door between open and closed positions, said operator unit including a reversible electric drive motor having a rotatable output shaft, a drive unit interconnecting said motor with a door and a control system including a programmable microcontroller including a memory, a keypad for providing information to said microcontroller and a visual display for displaying information associated with operation of said operator unit, said method including the step of:causing said visual display to display a fault code, a condition code and error codes associated with a fault condition of said operator unit and said control system, respectively.
  • 46. A control system for controlling the operation of a door operator unit to move a door between open and closed positions, said operator unit including a reversible electric drive motor, a drive unit interconnecting said motor with a door, and an electrically operated brake operably connected to said motor and said drive unit for braking rotation of an output shaft of said drive unit, said control system comprising:a programmable microcontroller operable to receive control signals from at least one of plural switches for providing door open, door close and door stop signals, and a single switch for sequentially providing door open, door close and door stop signals; a motor power supply control circuit for operating said motor in reverse directions of rotation; a motor drive circuit including motor drive relay actuators and at least two motor interlock relays in circuit with said motor drive relay actuators, respectively, said motor drive circuit being adapted to receive control signals from said microcontroller to effect operation of said motor through said motor power supply control circuit to provide for one of opening and closing said door and said motor interlock relays being operable to prevent energization of one of said motor drive relay actuators when the other of said motor drive relay actuators is energized to rotate said drive motor in a selected direction to one of open and close said door; and a brake control circuit operably connected to said microcontroller and operable to provide signals for releasing said brake and for progressively applying said brake to brake rotation of said output shaft.
  • 47. The control system set forth in claim 46 including:a motor drive status feedback circuit operably connected to said motor drive circuit and operable to receive a signal from said motor drive circuit when one or the other of said motor drive relay actuators and an associated motor interlock relay are energized to provide a feedback signal to said microcontroller.
  • 48. The control system set forth in claim 47 including:a motor watchdog circuit operably connected to said motor drive circuit and including a switch connected to said motor drive circuit and to means for receiving a signal from said microcontroller, said means being operable in response to not receiving a signal from said microcontroller to effect shutdown of said drive motor.
  • 49. The control system set forth in claim 48 wherein:said motor watchdog circuit is operably connected to said brake control circuit to prevent release of said brake when said microcontroller is inoperative.
  • 50. A control system for controlling the operation of a door operator unit to move a door between open and closed positions, said operator unit including a reversible electric drive motor, and a drive unit interconnecting said motor with a door, said control system comprising:a programmable microcontroller operable to receive control signals from at least one of plural switches for providing door open, door close and door stop signals, and a single switch for sequentially providing door open, door close and door stop signals; a motor power supply control circuit for operating said motor in reverse directions of rotation; a motor drive circuit including motor drive relay actuators and at least two motor interlock relays in circuit with said motor drive relay actuators, respectively, said motor drive circuit being adapted to receive control signals from said microcontroller to effect operation of said motor through said motor power supply control circuit to provide for one of opening and closing said door and said motor interlock relays being operable to prevent energization of one of said motor drive relay actuators when the other of said motor drive relay actuators is energized to rotate said drive motor in a selected direction to one of open and close said door; and a motor watchdog circuit operably connected to said motor drive circuit and including a switch connected to said motor drive circuit and to means for receiving a signal from said microcontroller, said means being operable in response to the absence of a predetermined signal from said microcontroller to effect shutdown of said motor.
  • 51. The control system set forth in claim 50 including:a motor drive status feedback circuit operably connected to said motor drive circuit and operable to receive a signal from said motor drive circuit when one or the other of said motor drive relay actuators and an associated motor interlock relay are energized to provide a feedback signal to said microcontroller.
  • 52. A method for controlling the operation of a door operator unit to move a door between open and closed positions, said operator unit including a reversible electric drive motor having a rotatable output shaft, a drive unit including an electrically actuated brake interconnecting said motor with a door and a control system including a programmable microcontroller including a memory, a keypad for providing information to said microcontroller and a visual display for displaying a condition code and calibration information associated with operation of said operator unit, said method including the steps of:using said keypad to select one of a door open mode of operation, a door close mode of operation, a calibration mode and selection of available calibration functions; and using said keypad to select at least one of a direction of output shaft rotation of said operator unit corresponding to a given direction of door travel and controlling direction sensitive input commands to said control system.
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4429264 Richmond Jan 1984 A
4498033 Aihara et al. Feb 1985 A
4583081 Schmitz Apr 1986 A
4625291 Hormann Nov 1986 A
4638433 Schindler Jan 1987 A
4887205 Chou Dec 1989 A
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5081403 Matsuura et al. Jan 1992 A
5633778 Chang et al. May 1997 A
5684372 Fitzgibbon et al. Nov 1997 A
5780987 Fitzgibbon et al. Jul 1998 A
5812391 Mehalshick Sep 1998 A
5841253 Fitzgibbon et al. Nov 1998 A
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