Method and apparatus for correcting cock driving device in beverage dispenser

Information

  • Patent Grant
  • 6715641
  • Patent Number
    6,715,641
  • Date Filed
    Tuesday, September 18, 2001
    22 years ago
  • Date Issued
    Tuesday, April 6, 2004
    20 years ago
Abstract
A method and apparatus for correcting a cock driving device in a beverage dispense. A manipulating lever for a dispensing cock is correctly opened and closed at all times by the cock driving device. The manipulating lever for the dispensing cock is provided with an interlock member which moves back and forth integrally with the lever, and the interlock member is provided with a magnet. A pair of hole elements capable of sensing the magnet are arranged one behind the other, spaced from each other, on a mounting plate arranged on a slider. The magnet is set to face an intermediate position of both hole elements of the slider staying at a standby position, with the dispensing cock staying at a neutral position. A control board moves the slider for correction to a position at which the magnet reaches the intermediate position of the hole elements if the magnet does not face the intermediate position of the pair of hole elements.
Description




FIELD OF THE INVENTION




This invention relates to a beverage dispenser, and more particularly, to a method and apparatus for correcting a cock driving device which automatically opens and closes a manipulating lever for a dispensing cock arranged on the body of a dispenser for dispensing a beverage.




DESCRIPTION OF THE RELATED ART




An apparatus for dispensing a sparkling drink through lever manipulations, for example, a beer server is provided with a manipulating lever on a dispensing cock arranged on its body. The lever is manually tilted in one direction to dispense a predetermined amount of beer into a mug, and then the lever is tilted in the opposite direction to pour fine foam of beer on the dispensed beer in the mug. However, in manually dispensing beer and foam through manipulations of the lever, the dispensed amounts may differ from one operator from another. To solve this problem, an automatic dispensing apparatus is disclosed in Japanese Unexamined Patent Publication No. Hei 9-48498 as a technique proposed for automatically manipulating the lever by a driving device. In this apparatus, a motor arranged in a body is coupled to a dispensing cock manipulating lever through an attachment and a screw shaft to move the manipulating lever back and forth by normal and reverse rotations of the motor to dispense beer and foam.




The above-mentioned automatic dispensing apparatus is configured to move the manipulating lever between an open position and a closed position by controlling a rotation time of the motor using a timer. In this event, a shift in positions at which the dispensing cock and motor are mounted, relative to the server body, would result in a shift in relative position of the motor to the manipulating lever. If the motor is controlled by a previously set timer in this state, the manipulating lever could not be fully opened or be moved more than necessary in an opening direction to apply a load on the lever. In addition, even if the manipulating lever is moved from the open state to the closed state, the lever is not stopped correctly at the closed position, resulting in a leak.




It should be noted that the closed position of the manipulating lever may shift due to aging changes such as deformation of a rubber material arranged in a dispensing cock for blocking a beer passage port due to abrasion, deformation of a mount for mounting a manipulating lever on a cock body due to forward and backward movements of the lever, and the like. Therefore, similar problems to the foregoing will arise if the manipulating lever is manipulated by a driving device with the shifted state left uncorrected.




SUMMARY OF THE INVENTION




The present invention has been made in view of and for preferably solving the foregoing defects inherent in the cock driving device for a beverage dispenser according to the prior art. It is therefore an object of the present invention to provide a method and apparatus for correcting a cock driving device in a beverage dispenser which are capable of correctly opening and closing a manipulating lever for a dispensing cock at all times using the cock driving device.




To solve the aforementioned problems and achieve the intended object, the present invention provides a method of correcting a cock driving device in a beverage dispenser comprising an actuator configured to come into engagement with a manipulating lever for a dispensing cock arranged on a body, wherein the actuator is moved to a standby position and to an operative position to move the manipulating lever to a closed position and to an open position, comprising the steps of:




sensing by sensing means provided in the actuator whether or not a sensed element of the manipulating lever staying at the closed position reaches a regular position with respect to the actuator staying at the standby position; and




moving the actuator for correction to a position at which the sensing means senses the arrival of the sensed element at the regular position, and setting this position as a new standby position if the sensing means does not sense the arrival of the sensed element at the regular position.




To solve the aforementioned problems and achieve the intended object, the present invention also provides an apparatus for correcting a cock driving device in a beverage dispenser comprising an actuator configured to come into engagement with a manipulating lever for a dispensing cock arranged on a body, wherein the actuator is moved to a standby position and to an operative position to move the manipulating lever to a closed position and to an open position, the cock driving device in the beverage dispenser, comprising:




a sensed element arranged in an interlock member integrally movable with the manipulating lever;




sensing means arranged in the actuator for sensing whether or not the sensed element of the manipulating lever staying at the closed position reaches a regular position with respect to the actuator; and




control means for moving the actuator for correction to a position at which the sensing means senses the arrival of the sensed element at the regular position if the sensing means does not sense the arrival of the sensed element at the regular position when the actuator is moved from the operative position to the standby position to move the manipulating lever from the open position to the closed position.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a vertical sectional view illustrating a cock driving device arranged in a beer server according to a preferred embodiment of the present invention in a state in which a manipulating lever can be automatically manipulated;





FIG. 2

is a plan view illustrating a main portion of a slider, the manipulating lever and a correcting apparatus according to the embodiment in a proper positional relationship;





FIG. 3

is a vertical sectional view illustrating a main portion of a cock driving device according to the embodiment;





FIG. 4

shows a relationship among the slider, the manipulating lever and the correcting apparatus when the slider according to the embodiment is moved to the advanced position, wherein (a) is a diagram viewed from a side for describing the operation, and (b) is a diagram viewed from above for describing the operation;





FIG. 5

shows a relationship among the slider, the manipulating lever and the correcting apparatus when the slider according to the embodiment is moved to the back position, wherein (a) is a diagram viewed from a side for describing the operation, and (b) is a diagram viewed from above for describing the operation;





FIG. 6

shows a relationship between a magnet and hole elements when the manipulating lever is shifted backward with respect to an engagement hole of the slider according to the embodiment, wherein (a) is an explanatory diagram viewed from a side, and (b) is an explanatory diagram viewed from above;





FIG. 7

shows a relationship between the magnet and the hole elements when the manipulating lever is shifted forward with respect to the engagement hole of the slider according to the embodiment, wherein (a) is an explanatory diagram viewed from a side, and (b) is an explanatory diagram viewed from above;





FIG. 8

is a vertical sectional view illustrating a main portion of a cock driving device which employs a feature for controlling the amount of movement of the slider according to a modification; and





FIG. 9

is a vertical sectional view illustrating a main portion of a cock driving device which employs a slider according to the modification.











DETAILED DESCRIPTION OF THE EMBODIMENT




Next, a method and apparatus for correcting a cock driving device in a beverage dispenser according to the present invention will hereinafter be described for a preferred embodiment thereof with reference to the accompanying drawings. It goes without saying that while the following embodiment is described for a beer server illustrated as an example of the beverage dispenser, the present invention is not limited to this but may be applied to a dispenser for dispensing juice, other beverages, and the like.





FIG. 1

illustrates a main portion of a beer server according to the preferred embodiment. A dispensing cock


12


is arranged on a front surface of a body


10


of the server, and a beer supply tube


14


, extending horizontally from the server body


10


, is connected to the cock


12


. The dispensing cock


12


is basically comprised of a cock body


16


which contains a variety of valve mechanisms (not shown) for opening/closing passage ways of beer and foam; and a manipulating lever


18


extending upward from the cock body


16


for switching beer and foam to be dispensed through forward and backward tilting operations. The cock body


16


in turn comprises a beer dispensing nozzle


20


and a foam dispensing nozzle


22


parallelly extending diagonally downward. In

FIG. 1

, the right-hand nozzle extending diagonally downward from the cock body


16


is the beer dispensing nozzle


20


, and the left-hand nozzle is the foam dispensing nozzle


22


.




The manipulating lever


18


, in this embodiment, is tilted forward to actuate (open) the valve mechanism to dispense beer from the beer dispensing nozzle


20


, and tilted backward to actuate (open) the valve mechanism to dispense foam from the foam dispensing nozzle


22


. Also, the manipulating lever


18


is positioned at a neutral position (a closed position substantially at a vertical posture) between a beer dispensing position (open position) and a foam dispensing position (open position) at all times, when not operated, by a spring of the valve mechanism contained in the cock body


16


, so that the valve mechanism is held in a closed state. Then, the manipulating lever


18


is configured for automatic manipulation by a cock driving device


24


arranged on the front surface of the server body


10


. On the front surface of the server body


10


, a carrier for carrying a mug (container), though not shown, is disposed at a position below the dispensing cock


12


, such that beer and foam are dispensed into a mug carried on the carrier.




The cock driving device


24


for automatically manipulating the manipulating lever


18


is basically comprised of a slider


28


contained in a housing


26


arranged for vertical movements relative to the server body


10


and acting as an actuator for horizontally advancing and retracting movements; and a driving mechanism (driving means)


30


for advancing and retracting the slider


28


. The housing


26


, as illustrated in

FIG. 3

, is configured such that a sliding body


32


arranged therein is vertically slidably engaged with a guide


34


arranged on the front surface of the server body


10


to allow the cock driving device


24


to move between an inoperative position spaced upward from the dispensing cock


12


and an operative position close to the dispensing cock


12


. The housing


26


is positioned at the inoperative position and the operative position with respect to the server body


10


through a latch


36


which is arranged in a rear portion of the bottom thereof. The housing


26


is also formed with a throughhole


26




a


, extending through a bottom plate thereof, which permits the manipulating lever


18


staying at the neutral position to be inserted therethrough and the lever


18


to be tilted back and forth.




A controller


38


which comprises dispensing buttons, a dispensing amount setting switch and the like is arranged in a front portion of the housing


26


. The controller


38


is connected to a control board


40


arranged in the housing


26


as control means for controlling the operation of the beer server.




On the top of the bottom plate of the housing


26


, a pair of opposing guide rails


42


(only one of which is illustrated) are arranged spaced apart in a width direction on both sides of the throughhole


26




a


. The guide rails


42


extend over a predetermined length in a front-to-back direction. The flat slider


28


is arranged on both guide rails


42


for horizontal movements in the front-to-back directions. The slider


28


is formed with an engagement hole


28




a


which permits the manipulating lever


18


to be inserted therethrough. When the housing


26


(cock driving device


24


) is positioned at the operative position, the manipulating lever


18


is inserted through the engagement hole


28




a


, as illustrated in

FIG. 3

, and the engagement hole


28




a


is engaged with the manipulating lever


18


by forward and backward movements of the slider


28


, so that the lever


18


can be tilted forward and backward. Also, when the housing


26


(cock driving device


24


) is positioned at the inoperative position, the engagement hole


28




a


comes off the manipulating lever


18


upward, so that the manipulating lever


18


can be manually tilted in the front-to-back directions.




The inner diameter of the engagement hole


28




a


is set larger than the outer diameter of a portion of the manipulating lever


18


which is inserted through the engagement hole


28




a


(see FIG.


2


), so that when the cock driving device


24


is positioned at the correct operative position with respect to the manipulating lever


18


correctly positioned at the neutral position, a required gap is formed between the outer peripheral surface of the manipulating lever


18


and the inner peripheral surface of the engagement hole


28




a


at least in front of and at the back of the manipulating lever


18


in the tilting directions, as illustrated in FIG.


3


. More specifically, even with a certain error in the positions at which the dispensing cock


12


and the cook driving device


24


are arranged with respect to the server body


10


, the engagement hole


28




a


of the slider


28


can be fitted over and removed from the manipulating lever


18


smoothly without causing any problems.




The driving mechanism


30


is comprised of a rack


44


arranged on the top of the slider


28


and extending over a predetermined length in the front-to-back direction; a pinion


46


meshed with the rack


44


; and a normally and reversely rotatable motor


50


connected to the pinion


46


through a gear train


48


. Then, by normally and reversely rotating the pinion


46


by the motor


50


, the slider


28


provided with the rack


44


meshed with the pinion


46


is horizontally moved in the front-to-back directions along a pair of guide rails


42


, such that the slider


28


can be positioned at the advanced position (operative position), illustrated in

FIG. 4

, at which the manipulating lever


18


is tilted forward from the neutral position, and at a back position (operative position), illustrated in

FIG. 5

, at which the manipulating lever


18


is tilted backward from the neutral position.




In a state before the driving mechanism


30


is operated, the slider


28


is positioned at a standby position (a position in

FIG. 3

) at which the manipulating lever


18


staying at the neutral position can be inserted through the engagement hole


28




a


. The advanced position and the back position of the slider


28


are fixedly set based on the standby position in consideration of the gap formed between the manipulating lever


18


and the engagement hole


28




a


, such that beer and foam can be efficiently dispensed with the valve mechanism being held in a fully opened state.




The motor


50


comprises a position detector such as a pulse generator which outputs pulses to the control board


40


, for allowing the control board


40


to monitor the amount of rotation (rotational speed) and a rotating direction of the motor


50


. In this embodiment, the motor


50


is controlled to rotate back and forth by previously set front and rear numbers of pulses with reference to the standby position of the slider


28


to move the slider


28


to the advanced position and to the back position. Specifically, when the number of pulses of the motor


50


for moving the slider


28


from the standby position to the advanced position reaches a forward set value based on the standby position, the motor


50


is stopped and reversely rotated after the lapse of a predetermined dispensing time. Also, when the number of pulses of the motor


50


for moving the slider


28


to the back position reaches a backward set value based on the standby position after the slider


28


is once returned from the advanced position to the standby position, the motor


50


is stopped and reversely rotated after the lapse of the predetermined dispensing time. The stopping time of the motor


50


, when the slider


28


reaches the advanced position and the back position is set in accordance with the amounts of dispensed beer and foam, and is previously set by the controller


38


.




The manipulating lever


18


of the dispensing cock


12


is provided with an interlock member


62


which is positioned below the slider


28


for moving back and forth integrally with the lever


18


, as illustrated in FIG.


1


. The interlock member


52


is implanted with a holder


54


which is inserted from below through an elongated hole


28




b


drilled through the slider


28


and extending in the front-to-back direction. The holder


54


is configured movable in the front-to-back directions relative to the elongated hole


28




b


. Also, a magnet


56


is arranged as a sensed element at a site of the holder


54


above the slider


28


. Further, on a mounting plate


58


implanted on the top of the slider


28


, a pair of hole elements


60




a


,


60




b


are arranged one behind the other along a direction in which the slider


28


is moved, as sensing means capable of sensing the magnet


56


. In this embodiment, with the manipulating lever


18


staying at the neutral position, the magnet


56


is set to face an intermediate position (regular position) of both hole elements


60




a


,


60




b


of the slider


28


staying at the standby position. The hole elements


60




a


,


60




b


magnetically detect a distance, so that a current position of the magnet


56


is sensed by the magnitude of magnetism detected by the front and rear hole elements


60




a


,


60




b.






On the control board


40


, the position of the slider


28


, when the magnet


56


faces the intermediate position (regular position) of the pair of hole elements


60




a


,


60




b


, is set as the standby position, and the motor


50


is pulse-controlled in the manner described above based on the standby position. Also, when the slider


28


returns to the standby position from the advanced position or the back position, i.e., when the manipulating lever


18


is moved to the neutral position (closed position), the motor


50


is controlled to rotate to move the slider


28


for correction until the magnet


56


comes to the intermediate position of the hole elements


60




a


,


60




b


, if the magnet


56


is not positioned at the intermediate position of the pair of hole elements


60




a


,


60




b


. Then, the position of the slider


28


at which the magnet


56


reaches the intermediate position is set as a now standby position of the slider


28


, so that the motor


50


is pulse-controlled from the next operation with reference to the new standby position. In this embodiment, a correcting apparatus is comprised of the interlock member


52


, the magnet


56


, the pair of hole elements


60




a


,


60




b


, and the control board


40


.




(Operation of Embodiment)




Next, the operation of the beer server according to the embodiment will be described below.

FIG. 1

illustrates the beer server in a state where the manipulating lever


18


for the dispensing cock


12


can be automatically manipulated by the cock driving device


24


. In this event, the manipulating lever


18


remains at the neutral position before manipulation, and is inserted through the engagement hole


28




a


of the slider


28


which is positioned at the standby position. The magnet


56


of the interlock member


52


in turn is detected to face the intermediate position which is the regular position with respect to both hole elements


60




a


,


60




b.






Depression on a dispensing button on the controller


38


arranged in a front portion of the housing


26


causes the motor


50


to rotate in a predetermined direction to move the slider


28


in front along the guide rails


42


through the gear train


48


, the pinion


46


and the rack


44


. With the forward movement of the slider


28


, the inner peripheral surface of the engagement hole


28




a


comes into contact with the manipulating lever


18


to tilt the lever


18


forward, as illustrated in FIG.


4


. As the slider


28


reaches the advanced position at which the manipulating lever


18


is tilted to the beer dispensing position (at the time the number of pulses reaches the preset value), the motor


50


is stopped, so that the slider


28


is positioned at the advanced position. In this way, beer in the beer supply pipe


14


is dispensed into a mug from the beer dispensing nozzle


20


.




As a previously set beer dispensing time has elapsed, the motor


50


is reversely rotated, causing the slider


28


to move from the advanced position to the standby position and then retract toward the back position. With the backward movement of the slider


28


, the manipulating lever


18


comes in contact with the inner peripheral surface of the engaging hole


28




a


to tilt the lever


18


backward, as illustrated in FIG.


5


. As the slider


28


reaches the back position at which the manipulating lever


18


is tilted to the foam dispensing position (at the time the number of pulses reaches the backward set value), the motor


50


is stopped, so that the slider


28


is positioned at the back position. In this way, the beer from the beer supply pipe


14


, formed into fine foam, is poured from the foam dispensing nozzle


22


on the beer stored in the mug.




Next, as a previously set foam dispensing time has elapsed, the motor


50


is again reversely rotated, causing the slider


28


to move forward from the back position to the standby position, so that the manipulating lever


18


returns to the neutral position, and the slider


28


is stopped at the standby position. In this event, even if the relative position of the manipulating lever


18


to the cock driving device


24


is shifted from the correct position, the manipulating lever


18


is prevented from coming in contact with the inner peripheral surface of the engagement hole


28




a


to fail to return to the neutral position because the inner diameter of the engagement hole


28




a


is set larger than the outer diameter of the manipulating lever


18


, as mentioned above. Thus, the valve mechanism will never be held opened, preventing beer and foam from leaking from the associated nozzles


20


,


22


.




Here, the neutral position of the manipulating lever


18


may be shifted due to displaced positions at which the dispensing cock


12


and the cock driving device


24


are mounted with respect to the server body


10


, or due to aging changes of the aforementioned rubber material and mounts. Consequently, as the slider


28


returns to the standby position, the position of the manipulating lever


18


with respect to the engagement hole


28




a


of the slider


28


would be shifted forward or backward as illustrated in

FIGS. 6 and 7

. In addition, even if the neutral position of the manipulating lever


18


remains unchanged, the slider


28


may not correctly return to the previously set standby position in some cases due to fluctuations in pressure of a load applied to the motor


50


. In this event, a shift would occur in the relative position of the manipulating lever


18


to the slider


28


, causing the magnet


56


to fail to reach the intermediate position of the pair of hole elements


60




a


,


60




b


. Specifically, in this event, since the hole elements


60




a


,


60




b


do not sense the arrival of the magnet


56


at the regular position, the control board


40


controls the motor


50


to rotate in a corresponding direction in accordance with the amount of shift of the magnet


56


with respect to the respective hole elements


60




a


,


60




b


to move the slider


28


for correction to a position at which the hole elements


60




a


,


60




b


sense that the magnet


56


reaches the intermediate position (regular position) of the hole elements


60




a


,


60




b.






For example, when the magnet


56


is closer to the rear hole element


60




b


as illustrated in

FIG. 6

, the slider


28


is retracted. On the other hand, when the magnet


56


is closer to the front hole element


60




a


as illustrated in

FIG. 7

, the slider


28


is advanced, and the motor


50


is stopped at the time the magnet


56


reaches the intermediate position of both hole elements


60




a


,


60




b


. Then, the position of the slider


28


at this time is set as a new standby position, so that the motor


50


is pulse-controlled with reference to this standby position in a subsequent dispensing operation performed by the cock driving device


24


. When the magnet


56


of the manipulating lever


18


reaches the intermediate position of the hole elements


60




a


,


60




b


, i.e., the regular position with respect to the slider


28


at the time the slider


28


has returned to the standby position, the correcting apparatus will not correct the standby position of the slider


28


.




Thus, the cock driving device


24


correctly opens and closes the manipulating lever


18


at all times, without the manipulating lever


18


failing to fully open, or excessively tilted in the opening direction to apply an extra load on the manipulating lever


18


. It is also possible to obviate the manipulating lever


18


from failing to precisely stop at the closed position to cause a leak. In the embodiment, since the motor


50


is pulse-controlled to move the slider


28


to the advanced position and the back position, no sensor or the like need be provided for actually sensing the slider


28


, thereby reducing the number of parts and saving the space. Further, since the hole elements


60




a


,


60




b


are used as sensing means for the correction control, the correcting apparatus can be reduced in size.




(Modification)




In the foregoing embodiment, while the amount of movement (the advanced position and the back position) of the slider


28


is set through the pulse control of the motor


50


, the aforementioned correcting apparatus may be employed for a cock driving device


24


which is configured to set the advanced position and the back position of the slider


28


by a detecting switch


64


which turns ON/OFF by an operating piece


62


provided on the slider


28


, for example, as illustrated in FIG.


8


. The slider may be comprised of a driving slider section


66


provided with a rack


44


meshed with a pinion


46


of a driving mechanism


30


; a driven slider section


68


formed with an engagement hole


68




a


through which the manipulating lever


18


is inserted; and a compression spring


70


as buffering means for integrally movably coupling both slider sections


66


,


68


. With the slider (actuator)


72


in this configurations when the driven slider section


68


is applied with a force exceeding a predetermined value, the driven slider


68


is allowed to come closer to or move away from the driving slider section


66


, thereby making it possible to prevent an excessively large force from being applied to the manipulating lever


18


and the driving mechanism


30


.




The driving means for horizontally advancing and retracting the slider is not limited to the configuration shown in the embodiment, but a variety of other mechanisms may be employed instead. Also, as the sensing means for sensing whether or not the sensed element of the manipulating lever has reached the regular position with respect to the actuator, a variety of sensors such as a proximity sensor and an opto-electric sensor may be used other than the hole element in the embodiment. When a proximity sensor or an opto-electric sensor is used, an associated sensed element may be formed of a material which can be sensed by the sensor.




As described above, the method and apparatus for correcting a cock driving device in a beverage dispenser according to the present invention senses a shift in the relative position of the manipulating lever staying at the closed position to the actuator staying at the standby position to correct the standby position of the actuator, so that the manipulating lever can be correctly manipulated to open/close through movements of the actuator. Therefore, even with an error in assembly of parts, aging changes and the like, the cock driving device correctly opens and closes the manipulating lever at all times, thereby preventing the manipulating lever from failing to fully open, preventing a load from being applied with the lever, and obviating the manipulating lever from failing to precisely stop at the closed position to cause a leak.



Claims
  • 1. A method of correcting a cock driving device in a beverage dispenser in a cock driving device for use with a beverage dispenser comprising an actuator configured to come into engagement with a manipulaling lever for a dispensing cock arranged on a body, the method comprising the steps of:moving said actuator to a standby position and to an operative position to move said manipulating lever to a closed position and to an open position; sensing by sensing means provided in said actuator whether or not a sensed element of said manipulating lever staying at said closed position reaches a regular position with respect to said actuator staying at said standby position; and moving said actuator for correction to a position at which said sensing means senses the arrival of said sensed element at the regular position, and setting this position as a new standby position if said sensing means does not sense the arrival of said sensed element at the regular position.
  • 2. An apparatus for correcting a cock driving device in a beverage dispenser in a cock driving device for use with a beverage dispenser, said apparatus comprising:an actuator configured to come into engagement with a manipulating lever for a dispensing cock arranged on a body, wherein said actuator is moved to a standby position and to an operative position to move said manipulating lever to a closed position and to an open position; a sensed element arranged in an intetlock member integrally movable with said manipulating lever; sensing means arranged in said actuator for sensing whether or not said sensed element of said manipulating lever staying at the closed position reaches a regular position with respect to said actuator; and control means for moving said actuator for correction to a position at which said sensing means senses the arrival of said sensed element at the regular position if said sensing means does not sense the arrival of said sensed element at the regular position when said actuator is moved from the operative position to the standby position to move said manipulating lever from the open position to the closed position.
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3718233 Nordhoff Feb 1973 A
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4226343 Fling Oct 1980 A
5022557 Turner Jun 1991 A
5044528 Becker Sep 1991 A
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5431302 Tulley et al. Jul 1995 A
5845824 Weimer et al. Dec 1998 A
6398084 Maruyama et al. Jun 2002 B2