Cage stop height readjusting apparatus for elevator system and method thereof

A cage stop height readjusting apparatus for an elevator system and a method thereof which are capable of accurately stopping a cage at a predetermined floor at a zero level of a cage stop height. The apparatus includes a position detection rotary encoder for outputting second pulse signal which corresponds to an actual running distance of a cage as a pulley is rotated by a wirET.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a cage stop height readjusting apparatus 
for an elevator system and a method thereof, and in particular to an 
improved cage stop height readjusting apparatus for an elevator system and 
a method thereof which are capable of accurately stopping a cage or an 
elevator car at a predetermined floor at a zero level of a cage stop 
height. 
2. Description of the Background Art 
Generally, in a conventional elevator system, a sensor connected with a 
shaft of a cage driving motor generates output pulses proportionally to 
the RPM of the motor. These output pulses from a rotary encoder are 
accumulatively summed in accordance with a running direction of the cage, 
thereby recognizing a synchronous position of the cage. 
Therefore, when initially installing an elevator, the height of each floor 
is measured and stored using the number of output pulses from the rotary 
encoder based on the position of a reference position (for example, the 
bottom of the lowest floor of a building). The cage is moved to the floor 
at which a cage call is generated based on the measured value. At this 
time, the position in which the bottom of the cage coincides with the 
height of the floor is called the zero level. 
When the cage arrives at the destination floor, the cage often reaches the 
designated floor at a certain distance away from the zero level due to the 
erroneous operation of a control apparatus or the characteristics of 
various sensors. In addition, after the cage arrives, when the load of the 
cage is varied due to the loading or unloading of the passenger, the 
elongation of a wire connected with the cage is varied, so that the cage 
stops at a certain distance short of or over the zero level of the 
designated floor. 
As a result, there may occur a problem such as a passenger getting-on and 
getting-ff problem due to the difference in height between the height of 
the desired floor and the height of the bottom of the cage both measured 
from a set reference position. Therefore, it is required to urgently 
adjust the stop height of the cage based on the zero level. At this time, 
the cage has to be re-driven to accurately adjust-the cage stop height. 
This operation is called a cage stop height readjusting operation. 
FIG. 1 illustrates a schematic block diagram illustrating a conventional 
position control apparatus for a conventional elevator, as disclosed in 
U.S. Pat. No. 4,719,994 issued on Jan. 19, 1988, which is hereby 
incorporated by reference. This control apparatus includes a motor 4 for 
generating a driving force and transferring the force to a sheave 3 for 
running a cage 1, a speed detection rotary encoder 5 connected with a 
driving shaft of the motor 4 for outputting a speed signal V.sub.T which 
is proportional to the RPM of the motor 4, a speed reference signal 
generator 6 for receiving position detection signals LU, LD and RL from 
the position detector 1a, 1b, 1c of the cage 1 and generating a speed 
reference signal V.sub.P for a cage stop height readjusting operation, a 
subtractor 7 for performing a subtraction operation between a speed signal 
V.sub.T from the speed detection rotary encoder 5 and a speed reference 
signal V.sub.P from the reference signal generator 6 and outputting a 
deviation V.sub.E, and a speed control apparatus 8 for controlling the RPM 
of the motor 4 based on the deviation V.sub.E from the subtractor 7. In 
the drawings, reference numeral 2 denotes a balance weight. 
In addition, the reference speed generator 6 as shown in FIG. 2 includes an 
input unit 6A for receiving the position detection signals LU, LD and RL, 
a CPU 6D for processing the position detection signals LU, LD and RL 
inputted through a ROM 6C, RAM 6B, the input unit 6A and the bus and 
outputting a reference speed signal V.sub.P, a timer 6E for generating a 
timing signal for an interrupt control, and an output unit 6F for 
outputting the reference speed signal V.sub.P computed. 
The operation of the conventional elevator position control apparatus in 
FIG. 1 will be explained. 
When the cage 1 arrives at the destination floor, the position detectors 1a 
, 1b, 1c installed on the cage 1 contact the position cam installed on 
each of the floors, and the position detector signals LU, LD and RL are 
transmitted to the reference speed generator 6 from the position detectors 
1a, 1b, 1c. 
FIGS. 3A-3C illustrate operational ranges of the position detection signals 
LU, LD and RL. 
ARL is the cage stop height readjusting zone range, which is composed of 
the zone A which indicates that the cage stop height readjusting operation 
is needed in the up-travel direction, the zone B which indicates the 
normal stop height range, and the zone C which indicates that the cage 
stop height readjusting operation, is needed in the down-travel direction. 
Here, the zero point denotes the actual level of the floor. 
Therefore, the CPU 6D of the reference speed generator 6 receives the 
position detection signals LU, LD and RL through the input unit 6A and the 
bus BUS, executes the program stored in the ROM 6C, and transmits the 
reference speed signal V.sub.P through the output unit 6F for the cage 
stop readjusting operation. 
FIG. 4 illustrates the patterns of the reference speed signal V.sub.P and 
the speed signal V.sub.T of the cage 1 for the cage stop height 
readjusting operation. 
In the zone A, the reference speed signal V.sub.P is increased by .DELTA.V 
step-by-step as shown in FIG. 4B for increasing the riding-on feeling of 
the cage, and at the speed V.sub.RL, for a determined time, the 
above-described state is maintained. Thereafter, when the cage comes into 
the zone B of the normal stop height, the reference speed signal V.sub.P 
becomes 0. 
As a result, the speed control apparatus 8 receives the reference speed 
signal V.sub.P through the subtractor 7, thus driving the motor 4. In the 
zone A, the cage 1 is moved in the up-travel direction. As shown in FIG. 
4, when the reference speed signal V.sub.P becomes 0, the speed signal 
V.sub.T is gradually decreased and then becomes 0. Therefore, the cage 1 
arrives at the zero level. 
The cage stop height readjusting operation will now be explained with 
reference to FIGS. 5 through 8. 
When the power is supplied, the program read from the ROM 6C is executed, 
the reference speed generator 6 is initialized, the timer 6E is driven, 
and an interrupt signal is inputted. 
When the interrupt signal is inputted from the timer 6E, the CPU 6D 
performs a processing routine for detecting the stop position of the cage 
1 as shown in FIG. 5. 
Namely, when the interrupt signal is inputted from the timer 6E, the CPU 6D 
judges whether the cage 1 is running in Step S1. As a result of the 
judgment, if the cage 1 is running, the flag FLAG is set to 0 in Step S7. 
If the cage 1 is stopped, it is checked whether the position detection 
signal RL, namely, the ARL, is at a high level in the zone A in Step S2. 
As a result of the checking step, if the ARL is at a high level, the CPU 6D 
checks the level of the position detection signal LU or the position 
detection signal LU in the zone A, and thereafter it determines where the 
cage 1 is stopped among the zones A, B and C in Steps S3 and S4. 
If the position detection signal LU is detected to be at a low level in the 
zone A, the CPU 6D outputs an up movement instruction to the speed control 
apparatus 8 through the output unit 6F. If the position detection signal 
LU is at a high level and the position detection signal LD is at a low 
level in the zone C, the CPU 6D outputs the down movement instruction to 
the speed control apparatus 8 through the output unit 6F. Thereafter, the 
flag FLAG is set to 1 in Steps S5, S6 and S8. 
In the zone B, the position detection signals LU and LD are all at high 
levels. If the cage 1 is stopped in the normal zone B in which the cage 
stop height readjusting operation is not needed, the flag FLAG is set to 0 
in Step S7. At this time, the flag FLAG denotes whether the reference 
speed signal V.sub.P is computed for the cage stop height readjusting 
operation. 
When the processing routine for detecting the stop position of the cage 1 
is finished, the CPU 6D checks the flag FLAG. If the flag FLAG is set to 
1, the computation processing routine of the reference speed signal 
V.sub.P as shown in FIG. 6 is performed for the cage stop height 
readjusting operation. 
Namely, if the flag FLAG is set to 1 in Step S9, the CPU 6D checks whether 
the position detection signals LU and LD are all at high levels in Step 
S10. As a result of the checking, if the position detection signals LU and 
LD are all at high levels, the reference speed signal V.sub.P is set to 0 
in Step S11. 
As a result of the checking, if the position detection signals LU and LD 
are not all at high levels, the CPU 6D compares the reference speed signal 
V.sub.P with a constant speed V.sub.RL in Step S12. If the speed V.sub.RL 
is not higher than the reference speed signal V.sub.P, the reference speed 
signal V.sub.P is set to the V.sub.RL in Step S14 so that the cage 1 is 
accurately stopped in the normal zone B. If the speed V.sub.RL is higher 
than the reference speed signal V.sub.P, the reference speed signal is set 
to the current reference speed signal V.sub.P plus an increase .DELTA.V in 
Step S13. 
In addition, FIGS. 7 and 9 illustrate other examples of the patterns 
between the reference speed signal V.sub.P and the speed signal V.sub.T of 
the cage 1 for the cage stop height readjusting operation in the 
conventional art. 
FIG. 7 illustrates a pattern when the cage 1 is stopped in the normal zone 
B. At this time, since the cage 1 moves into the normal zone B before the 
reference speed signal V.sub.P reaches the speed signal V.sub.T of the 
cage 1, the reference speed signal V.sub.P becomes 0. 
Therefore, even when the cage stop height readjusting operation is 
finished, the distance L which is a distance from the zero level is 
increased compared to the distance as shown in FIG. 4. 
In addition, FIG. 8 illustrates a pattern for overcoming the problems which 
occur in the example of FIG. 7. As shown therein, when the cage 1 is 
moving, the reference speed signal V.sub.P is increased up to V.sub.M, and 
then the same is slightly decreased down to a predetermined speed 
V.sub.RL. As a result, since the reference speed signal V.sub.P of the 
cage 1 is quickly increased and is larger than the pattern shown in FIG. 
7, it is possible to shorten the distance L which is at a certain distance 
from the zero level. 
Namely, if the flag FLAG is set to 1, the CPU 6D checks whether the 
position detection signals LU and LD are all at high levels in Steps S15 
and S16. As a result, if the position detection signals LU and LD are all 
at high levels, the reference speed signal V.sub.P is set to 0, and the 
flag STA is set to 0 in Steps S17 and S18 for the cage stop height 
readjusting operation. 
If the position detection signals LU and LD are all at low levels, it is 
checked in Step S19 whether the flag STA is set to 0. As a result, if the 
flag STA is set to 0, the CPU 6D sets the reference speed signal V.sub.P 
to a certain speed V.sub.M in Step S20. In addition, the flag STA is set 
to 1 in Step S21. At this time, V.sub.M becomes two or three times the 
V.sub.RL. 
If the flag STA is not set to 0, the CPU 6D compares the reference speed 
signal V.sub.P with the speed V.sub.RL in Step S22. If the speed V.sub.RL 
is larger than the reference speed signal V.sub.P, the reference speed 
signal V.sub.P is set to V.sub.P +.DELTA.V in Step S23, and if the speed 
V.sub.RL is smaller than the reference speed signal V.sub.P, the reference 
speed signal V.sub.P is set to V.sub.RL in Step S24. Thereafter, the cage 
1 is accurately stopped in the normal zone B. 
Therefore, when the cage 1 is stopped in the normal zone B, since the cage 
1 is re-driven using the reference speed signal V.sub.P, it is possible to 
shorten the distance L which is a certain distance from the zero level. 
However, even when the cage stop height readjusting technique as shown in 
FIGS. 8 and 9 is used, in the conventional art since the cage 1 stops at a 
distance L from the zero level, there is a big problem for accurately 
stopping the cage at the zero level. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a cage 
stop height readjusting apparatus for an elevator system and a method 
thereof which overcome the aforementioned and other problems encountered 
in the background art. 
It is another object of the present invention to provide a cage stop height 
readjusting apparatus for an elevator system and a method thereof which 
are capable of accurately stopping a cage at a predetermined floor at a 
zero level of a cage stop height. 
To achieve the above and other objects, there is provided a cage stop 
height readjusting apparatus for an elevator system, which includes a 
position detection rotary encoder for outputting a second pulse signal 
which corresponds to an actual running distance of a cage as a pulley is 
rotated by a wire connected with the cage, and a main controller for 
receiving first and second position detection signals from first and third 
position detectors and first and second pulse signals from the speed 
detection rotary encoder and the position detection rotary encoder when 
the cage is stopped in a cage stop height readjusting zone, computing a 
cage stop height adjusting distance, and outputting a speed instruction 
signal for the cage stop height adjusting operation based on the computed 
cage stop height adjusting distance. 
To achieve the above and other objects, there is provided a cage stop 
height readjusting method for an elevator system, which includes a first 
step for obtaining minimum values of first and second position detection 
signals from the position detectors when the cage is stopped at a stop 
level and obtaining maximum values of the first and second detection 
signals when the cage is stopped at a certain distance from the stop 
level, a second step for initializing a buffer storing a relative distance 
value when the cage comes into a door zone and storing a running direction 
of the cage, a third step for storing the value, which is obtained by 
accumulatively summing the number of pulses in the second pulse signal 
output from the position detection rotary encoder, into a buffer as the 
relative distance value until the cage coming to the door zone is stopped, 
a fourth step for reading the stored running direction of the cage when 
the cage is stopped in the cage stop height adjusting zone and obtaining 
the current position of the stopped cage, a fifth step for computing a 
cage stop height adjusting distance between the zero level to the current 
position at which the cage is stopped, a sixth step for computing a speed 
pattern constant value for obtaining a speed pattern for re-running by the 
computed cage stop height adjusting distance after setting the re-running 
direction, and a seventh step for generating a shaped speed pattern based 
on the computed speed pattern constant value, generating the final speed 
instruction signal based on the generated speed pattern and re-running the 
cage. 
Additional advantages, objects and features of the invention will become 
more apparent from the description which follows.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 10 illustrates an embodiment of the cage stop height readjusting 
apparatus for an elevator system according to the present invention. 
As shown therein, position detectors 101 through 103 are installed on the 
cage 100. A shielding plate 104 is installed in each cage moving path of a 
corresponding floor to correspond with the position detectors 101 through 
103. When the cage 100 stops at the zero level, as shown in FIG. 13B, the 
position detector 102 stops at the center of the shielding plate 104, and 
the position detectors 101 through 103 are shielded by a predetermined 
range thereof (for example, the half portion each thereof). 
In addition, there are provided a pulley 108 which is rotated by a 
connection with the cage 100, a position detection rotary encoder 109 for 
outputting a pulse signal PUL2 corresponding to the actual running 
distance of the cage 100 as the pulley 108 is rotated, a main controller 
110 for receiving position detection signals MD, FML and MU from the 
position detectors 101 through 103 and pulse signals PUL1 and PUL2 from 
the speed detection rotary encoder 107 and the position detection rotary 
encoder 109, and outputting a speed instruction signal V*, and an inverter 
111 for phase-converting the speed instruction signal V* and driving a 
motor 106. In the drawings, reference number 105 denotes a sheave. 
As shown in FIG. 12, the main controller 110 basically includes the CPU 10, 
ROM 11 and RAM 12 and further includes pulse shaping units 13 and 14 for 
shaping the pulse signals PUL1 and PUL2 from the speed and position 
detection rotary encoders 107 and 109, pulse counters 15 and 16 for 
accumulatively summing and subtracting the output signals from the pulse 
shaping units 13 and 14, speed and position detectors 17 and 18 for 
detecting the speed and position of the cage 100 based on the output 
signals from the pulse counters 15 and 16, A/D converters 19 and 20 for 
analog-to-digital converting the position detection signals MU and MD, and 
a parallel input unit 21 for inputting the position detection signal FML. 
The operation of the cage stop height readjusting operation of the elevator 
system according to the present invention will now be explained with 
reference to the accompanying drawings. 
When the cage 100 arrives at a destination floor, the position detectors 
101 through 103 installed on the upper portion of the cage 100 output 
position detection signals MD, FML and MU to the main controller 110 based 
on the shielding operation of the shielding plate 104. 
In addition, the speed detection rotary encoder 107 connected with a 
driving shaft of the motor 106 outputs a pulse signal PUL1 proportional to 
the RPM of the motor 106, and the position detection rotary encoder 109 
outputs a pulse signal PUL2 corresponding to the actual running distance 
of the cage 100 based on the rotation of the pulley 108. 
FIG. 13 illustrates an operational principle of the position detector 102. 
The position detector 102 includes a read switch 102A and a permanent 
magnet 102B. At the usual time, the read switch 102A remains in an OFF 
state by the magnetic flux of the permanent magnet 102B as shown in FIG. 
13A. When the cage 100 is stopped at a predetermined floor, the magnetic 
flux is shielded by the shielding plate 104, and the read switch 102A is 
opened as shown in FIG. 13B. Therefore, the operational range of the 
position detector 102 is defined by the range of the length of the 
shielding plate 104 with respect to the zero level of the cage stop height 
as shown in FIG. 17. 
In addition, FIG. 14 illustrates an operation principle of the position 
detectors 101 and 103. The voltage, which is induced between the primary 
coil L11 and the secondary coils L21 and L22, is outputted as the position 
detection signals MD and MU. When the cage 100 stops at the zero level, 
the induced voltage is shielded by the shielding plate 104. At this time, 
if the shielding operation is not performed by the shielding plate 104, 
assuming that the voltage values (digitalized) of the position detection 
signals MU and MD are 255, and the digital value is 0 when the shielding 
is fully performed, the operational range of the position detectors 101 
and 103 is smaller than 200 as shown in FIG. 18. Other types of position 
detectors 101 through 103 may be used. 
Therefore, the main controller 110 receives the pulse signals PUL1 and PUL2 
from the speed and position detection rotary encoders 107 and 109, and 
these signals are shaped by the pulse shaping units 13 and 14. A number of 
pulses are accumulatively summed or subtracted by the pulse counters 15 
and 16. The speed and position detectors 17 and 18 respectively detect the 
running speed and position of the cage 100 based on the counted values of 
the pulse counters 15 and 16, and output the results to the CPU 10 through 
the bus BUS. 
In addition, the A/D converters 19 and 20 receive the position detection 
signals MU and MD induced by the secondary coils L21 and L22 of the 
position detectors 101 and 103, converts the same into digital values 0 
through 255 and outputs the results to the CPU 10. The output values from 
the A/D converters 19 and 20 are shown in FIG. 18. In addition, the 
parallel input unit 21 for processing the ON/OFF signals converts the 
position detection signal FML from the position detector 102 into ON-OFF 
signals. 
Therefore, the CPU 10 performs an arithmetic operation with respect to the 
data using the program read from the ROM 11, and the speed instruction 
signal V* is outputted to the inverter 111. The inverter 111 converts the 
phase of the speed instruction signal V* and drives the motor 106 
according to the speed instruction signal V*. 
As shown in FIG. 17, assuming that the length of the shielding plate 104 is 
250 mm, the cage 100 is stopped at a distance of .+-.125 mm from the zero 
level, and the widths of the door zone and the position detectors 101 and 
103 are 50 mm, respectively, then the position of the cage 100 is arranged 
from +125 mm through +20 mm or -125 mm through -20 mm as the cage stop 
height readjusting zone. 
Therefore, when the cage 100 comes into the door zone, the main controller 
110 accumulatively sums the number of pulse signals PUL2 from the rotary 
encoder 108 from the time when the output value MD from the position 
detector 101 or the output value MU from the position detector 103 becomes 
smaller than 128 to the time when the same becomes larger than 128 as 
shown in FIG. 18. 
Thereafter, when the cage 100 is stopped within the cage stop height 
readjusting zone, the distance, namely, 125 mm, from the zero level to the 
position at which the cage 100 is stopped is computed based on the number 
of stored pulses. Thereafter, the speed pattern by which the cage 100 
re-runs for the computed distance is generated. 
Next, the cage stop height readjusting operation will now be explained. 
First, when repairing or maintaining the elevator system, a user positions 
the cage 100 at the level of a corresponding floor and sets the flag SREQ, 
which indicates the minimum value setting request, to 1. Then the minimum 
values MU.sub.-- LR and MD.sub.-- LR of the position detection signals MU 
and MD output from the position detectors 101 and 103 are obtained, and 
the flag SREQ is set to 0. 
In addition, the cage 100 is moved to the positions 0 through .+-.250 which 
are at a certain distance from the stop level, and the flag SREQ is set to 
2 at the position. The maximum values MU.sub.-- MR and MD.sub.-- MR of the 
position detection signals MU and MD from the position detectors 101 and 
103 are stored. At this time, the flag (SREQ)="1" indicates the minimum 
value setting request, and the flag (SREQ)="2" indicates the maximum value 
setting request. 
Namely, as shown in FIG. 19, the CPU 10 checks whether the minimum value 
setting request is generated by a user in Step S100, and as a result of 
the checking, if there is a maximum value setting request, the digital 
values of the position detection signals MU and MD are received through 
the A/D converters 19 and 20. The digital values of the position detection 
signals MU and MD are stored into the RAM 12 as the minimum values 
MU.sub.-- LR and MD.sub.-- LR of the position detection signals MU and MD 
in Step S101, and the flag SFLAG is set to "1", thus indicating the 
minimum value setting completion in Step S102. 
In addition, if the flag SREQ is not set to 1, it is checked whether the 
minimum value setting operation is finished in Step S103. When the minimum 
value setting is finished, it is checked whether there is a maximum value 
setting request in Step S104. If there is the maximum value setting 
request, the digital values of the position detection signals MU and MD 
are received through the A/D converters 19 and 20. The digital values of 
the position detection signals MU and MD are stored into the RAM 12 as the 
maximum values MU.sub.-- MR and MD.sub.-- MR of the position detection 
signals MU and MD in Step S105, and the flag SFLAG is set to 2, thus 
indicating the maximum value setting completion in Step S106. As this 
time, the flag SFLAG is the flag which indicates the minimum value and 
maximum value setting completion of the position detectors 101 and 103. 
Thereafter, when the cage 100 comes into the door zone, the position 
detectors 101 and 103 are shielded by the shielding plate 104. At this 
time, the CPU 10 checks whether the maximum value setting operation is 
finished in Step S107. When the maximum value setting is finished, if the 
maximum value MU.sub.-- MR of the position detection signal MU is smaller 
than the digital value of the position detection signal MU which is 
currently detected by the position detector 103 in Step S108, and at the 
same time if the minimum value MD.sub.-- LR of the position detection 
signal MD is larger than or identical to the digital value of the position 
detection signal MD which is currently detected by the position detector 
101 in Step S109, the cage stop height readjusting interval (zone) A is 
set as shown in FIG. 17, and the running direction tmp of the cage 100 is 
in the up direction in Step S110. 
In addition, if the maximum value MD.sub.-- MR of the position detection 
signal MD is smaller than the digital value of the position detection 
signal MD which is currently detected by the position detector 101 in Step 
S111, and at the same time if the minimum value MU.sub.-- LR of the 
position signal MU is larger than or identical to the digital value of the 
position detection signal MU which is currently detected by the position 
detector 103 in Step S112, the cage stop height readjusting interval 
(zone) B is defined as shown in FIG. 17, and the running direction tmp of 
the cage 100 is in the down direction in Step S113. Thereafter, it is 
checked whether the cage 100 is stopped in Step S114. 
At this time, if the absolute value computation flag ABS is not set to 1 in 
Step S115, then the absolute value computation flag ABS is set to 1, the 
buffer DELT into which the relative distance value is stored is 
initialized, the flag INT which indicates the initialization of the buffer 
DELT is initialized, and the running direction tmp is stored in Step S116. 
In addition, if the cage 100 is stopped in the cage stop height 
readjusting zone (interval), and the buffer DELT is initialized in Step 
S117, then the flag START is set to 1 which indicates that the current 
position of the cage 100 is computed. If a predetermined condition is 
generated for the next cage stop height readjusting operation, the 
absolute value computation flag ABS is initialized for the cage stop 
height readjusting operation in Step S118. 
In a state where the maximum value setting is completed in Step S119, as 
shown in FIG. 21, when a request is generated for computing the relative 
distance value in Step S120 (ABS=1), the value which is obtained by 
accumulatively computing the pulse signals PUL2 from the position 
detection rotary encoder 108 at the door zone entering position, namely, 
the position at which the cage 100 is stopped from the shielding position, 
is stored into the buffer DELT in Step S121, and it is checked that 
whether there is a request for computing the current position CUR at which 
the cage 200 is positioned in Step S122. 
As a result of the checking, if there is a request for obtaining the 
current position CUR of the cage 100 stopped, the flag START is 
initialized, and the flag INIT is set to 1 in Step S123. If the cage 100 
is moved in the up-direction, the current position CUR is obtained based 
on the value of "the stored value of the buffer DELT+the zero level-125 
mm" in Steps S124 and S125. If the cage 100 is moved in the 
down-direction, the current position CUR is obtained based on the stored 
value of "the buffer DELT+the zero level value+125 mm" in Step S126. 
Thereafter, the distance from the zero level to the position at which the 
cage is currently stopped (namely, the cage stop height readjusting 
distance Dist) is computed, and the speed pattern is generated for 
re-running the cage 100 by the computed distance Dist. 
Namely, if the current position CUR of the cage 100 is larger than the zero 
level, the zero level is subtracted from the current position CUR, thus 
computing the cage stop height adjusting distance Dist, and the cage 100 
is set to move in the down-direction for performing the cage stop height 
readjusting operation by the cage stop height adjusting distance Dist in 
Steps S127 through S129. If the current position CUR of the cage 100 is 
smaller than the zero level, the current position CUR is subtracted from 
the zero level, thus computing the cage stop height adjusting distance 
Dist, and the running direction R.sub.-- DIR of the cage 100 is set to be 
moved in the up-direction for performing the cage stop height adjusting 
operation by the cage stop height adjusting distance Dist in Steps S130 
and S131. 
In addition, constant values T1, T2 and J1 are obtained for re-running the 
cage 100 based on the computed cage stop height adjusting distance Dist. 
At this time, the speed pattern shown in FIG. 18 may be expressed in the 
following Equation (1). 
EQU Dist=2J(k.sub.1 T).sup.2 (k.sub.2 T) Equation (1) 
where the reference value of J is 0.25, and since T1 is fixed, the value 
may be divided based on the zone. At this time, the reference value for 
dividing the zone is the maximum distance (0.625 m) when t2 is 0 as shown 
in FIG. 18. Therefore, the type of the speed pattern is divided into the 
types shown in FIGS. 15 and 18 based on the maximum distance. 
If Dist&lt;0.625 m in Step S132 and since in the interval "a" shown in FIG. 
17, t2 is 0, and t1 is 0.5 as shown in FIG. 15, then the new value J 
(namely, J.sub.1) is obtained based on the cage stop height adjusting 
distance Dist in Dist-2J(k.sub.1 T).sup.3 in Step S133. 
In addition, if Dist.gtoreq.0.625 m in Step S132, since the reference value 
of J is 0.25, and t1 is fixed to 0.5 in the interval "b" as shown in FIG. 
17, then k.sub.2 T, namely, t2 is obtained based on Dist-2J(k.sub.1 
T).sup.3 +J(k.sub.1 T).sup.2 (k.sub.2 T), and t2 is instituted, thus 
obtaining a new value of J (namely, J.sub.2) in Step S134. 
As a result, the shaped speed pattern is generated in accordance with the 
constant values T1, T2 and J1, and the CPU 10 outputs a speed instruction 
signal V* to the inverter 111 based on the speed pattern. The inverter 111 
phase-converts the speed instruction signal V* of the main controller 110, 
thus driving the motor 106 so that the cage 100 is accurately stopped at 
the zero level. 
As described above, in the present invention, the distance between the zero 
level and the cage is obtained using the output signals from the position 
detection rotary encoder and the position detector, the constant value of 
the shaped speed pattern function is computed in accordance with the 
obtained distance, and the speed instruction signal V* is generated based 
on the speed pattern by the computed constant values, thus enhancing the 
performance of the cage stop height readjusting operation. 
Although the preferred embodiments of the present invention have been 
disclosed for illustrative purposes, those skilled in the art will 
appreciate that various modifications, additions and substitutions are 
possible, without departing from the scope and spirit of the invention as 
recited in the accompanying claims.