Method for regeneration of a water softener

A demand initiated method for regenerating a water softener which operates the softener ion exchange bed over a capacity range in which the resin is most efficiently restored by exposure to brine. The reserve capacity of the softener is adjusted in response to the amount of softening capacity used since the last regeneration, as is the quantity of saturated brine to be used for the next regeneration, which is scheduled when the reserve capacity is exceeded, or the remaining available capacity will not be adequate for normal usage on the next day of the week.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a novel method and apparatus for 
regenerating the water softening or conditioning material in an automatic 
water softener system. 
2. Background Information 
Water softening with ion exchange material, such as resin particles or the 
like, is well known in the art. During the softening process, typically 
called the service cycle, the ion exchange resin particles acquire 
hardness inducing ions from raw water which is being treated, in exchange 
for soft ions. That is, ions which do not induce hardness to water. After 
continued contact of the resin particles with hard raw water, the 
particles ion exchange capacity is considerably diminished and 
regeneration of the resin particles must be accomplished, conventionally 
by contacting the resin particles with a brine solution, i.e., an aqueous 
solution of sodium chloride or potassium chloride or the like, during a 
regeneration cycle. 
The ion exchange process, which takes place during the regeneration of the 
ion exchange material, is accomplished in a softener or resin tank of well 
known construction. A separate brine tank is conventionally used to form 
brine for use during the regeneration cycle. When regeneration is 
initiated in the softener system, brine drawn from the brine tank passes 
through the bed of ion exchange material in the softener tank to reverse 
the exchange of ions and revitalize the bed by removing hardness inducing 
ions and replacing them with sodium ions, for example, from the brine. 
The amount of brine which is required to regenerate a bed of ion exchange 
material of a predetermined volume, is dependent upon the extent to which 
the bed is exhausted during the service cycle. This, in turn, is dependent 
upon a number of factors, including: (1) the hardness of the water being 
treated; and (2) the quantity of water treated during the service cycle. 
The cost of operating the softening system may be reduced by limiting the 
amount of salt utilized in each regeneration cycle and the frequency of 
regeneration cycles to only that necessary to regenerate the resin 
particles. 
Most water softeners are designed to regenerate on a predetermined timed 
cycle which is determined by taking into consideration the above-mentioned 
factors. The water softening system regenerates itself on the 
predetermined time cycle even if the water softening system is subjected 
to either an abnormally high or low usage during a particular period of 
time. In the instance of abnormally low usage, a waste of salt and water 
results. In the instance of abnormally high usage, the water softening 
system is unable to adequately soften all of the water passing through the 
system. 
Many control systems have been proposed to take into account water usage on 
a real time basis. Such systems have been based upon means which detect 
the state of exhaustion of the resin bed or means which measure the 
quantity of water which has passed through the resin bed since the most 
recent regeneration cycle. 
Systems which attempt to detect the state of exhaustion of the resin bed 
are disclosed in U.S. Pat. Nos. 3,246,759 and 4,257,887. These systems 
utilize electrodes, mounted in the resin bed, which are connected to a 
circuit which detects the condition of the resin bed. When the condition 
of the resin bed is such that rejuvenation should occur, a control circuit 
is activated to start the regeneration cycle. These systems, which rely on 
the difference in conductivity between beds of exhausted and rejuvenated 
resin particles, have not been completely reliable, are relatively 
expensive, and may result in salt usage which is not always in direct 
proportion to the volume of water processed. 
One example of a softening control system which utilizes a means to measure 
the quantity of water which has passed through the bed is disclosed in 
U.S. Pat. No. 3,687,289. This system utilizes a metering device associated 
with the soft water line to draw off a predetermined proportion of the 
water flowing from the soft water line. The drawn-off water is directed to 
a pump chamber having an adjustable water storage capacity. The amount of 
water drawn off from the soft water line is directly proportional to the 
storage capacity of a pump chamber. The water stored in the pump chamber 
is periodically directed to the brine storage tank. The brine storage tank 
includes means to activate a timer when the water level in the brine tank 
reaches a predetermined level to signal the need for regeneration. The 
predetermined proportion of water drawn off is adjusted dependent upon the 
hardness of the water being treated. 
The above discussed water softener systems signals a regeneration after the 
usage of a predetermined amount of soft water. However, the regeneration 
cycle is usually delayed so as to occur at night. Therefore, the resin bed 
must have a reserve capacity to provide soft water for the remaining 
portion of the day after the need for a regeneration is signaled. The 
reserve capacity is typically selected to be that remaining after 
approximately 70% of the capacity of the resin bed is used. This large 
reserve capacity is needed to maintain soft water service in the event 
that the need for regeneration is signaled early in the day. Although such 
water softener systems may be designed or adjusted to vary the reserve 
capacity of the resin bed, once determined, the reserve capacity becomes 
fixed. 
More recently, a water softener system has been designed which utilizes a 
micro-computer to adjust the reserve capacity from day to day in response 
to soft water usage. The system includes a turbine water meter which 
measures the quantity of water passing through the resin bed. Based upon 
the quantity and hardness of the water which has passed through the resin 
bed, the micro-computer calculates the percentage of the capacity of the 
resin bed used since the last regeneration. The micro-computer employs an 
algorithm to make calculations and decisions based on accumulated time and 
water use. The algorithm allows a large reserve for days immediately 
following a regeneration and reduces the amount of reserve capacity as 
more days of significant water usage accumulate since the most recent 
regeneration. At such time as the reserve capacity for a day is reached, 
the water softener is scheduled for regeneration that night with a 
preselected fixed quantity of salt. 
A system similar to the just described system utilizes a similar algorithm 
with additional criteria for reducing the probability of actual usage 
exceeding the variable reserve. This system determines and stores water 
average usage for each particular day of the week. At the end of each day 
the calculated reserve capacity remaining in the resin bed is determined 
and compared with the stored water usage average for the next day. If the 
reserve capacity remaining is not adequate to meet the expected demand on 
the next day, the water softener is scheduled for regeneration that night 
with a preselected fixed quantity of salt. 
The just described micro-computer systems utilize a variable reserve 
capacity and are able to schedule regenerations more in proportion to 
water usage and to thereby more accurately reduce the reserve capacity of 
the resin bed at the time of regeneration. However, both of these systems 
use a fixed quantity of salt for each regeneration. That is, the quantity 
of brine solution directed through the resin bed is the same during each 
regeneration. Accordingly, in instances where the reserve capacity of the 
resin bed is relatively high at the time of regeneration, a greater 
quantity of salt is passed through the bed than is necessary to rejuvenate 
the resin particles in the bed. As a result salt is wasted. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of this invention to provide a demand 
initiated method for regenerating a water softener which will maximize the 
efficient use of salt and minimize the use of water for regeneration, and 
prevent the exhaustion of the softening ability of the ion exchange resin 
bed prior to a regeneration. It is a further object of this invention to 
operate the softener ion exchange bed over a capacity range wherein the 
resin is most efficiently restored by exposure to brine. 
In accordance with this invention a water softener system is provide which 
employs a method of regeneration which both maximizes the efficient use of 
salt and minimize the use of water for regeneration. With usage following 
normal usage patterns for the system, the method of regeneration employed 
by the system also prevents the exhaustion of the softening ability of the 
ion exchange resin bed prior to a regeneration. Further, the method of 
operating the system causes the ion exchange bed to function over a 
capacity range wherein the resin is most efficiently restored by exposure 
to brine. 
The water softener system of the present invention is operated according to 
a method which measures the amount of softening capacity of resin bed used 
since the last regeneration, adjusts the reserve capacity periodical in 
accordance with soft water usage, and further employs a method of 
determining the quantity of salt to be used during each regeneration of 
the system. The system of this invention employs automatic means to make 
efficient use of the water softener's residual capacity which remains when 
the softener's resin bed is regenerated prior to complete exhaustion. The 
present invention further maximizes the efficient use of salt during each 
regeneration by selecting a quantity of salt needed to regenerate the 
resin bed to a preselected design capacity, which preselected design 
capacity is less than the maximum or theoretical capacity of the resin 
bed. More specifically, the method of regenerating a water softener in 
accordance with this invention, includes making an initial selection of a 
design exchange capacity to which the resin bed is to be regenerated 
during each regeneration cycle. This design exchange capacity is 
preferably approximately equal to the exchange capacity in grains of the 
resin bed at that particular salt dosage wherein the exchange capacity in 
grains of the bed divided by the particular salt dosage in pounds is at 
least approximately 3350. It has been determined that such a design 
exchange capacity makes efficient use of the brine solution during each 
regeneration cycle. The system is regenerated, when at the end of any 
preselected time period, the percentage of the design capacity of the 
resin bed used since the last regeneration cycle exceeds a predetermined 
percentage in the range of 50 to 100 percent. The resin bed is regenerated 
with a brine solution made with a salt dosage which is approximately equal 
to that which is necessary to regenerate the resin bed to its design 
capacity. 
Prior to using the system of this invention, the exchange capacity of the 
resin bed is determined for various salt dosages. The exchange capacity of 
the resin bed for each particular salt dosage is approximately equal to 
the capacity of the resin bed subsequent to regeneration with the 
particular salt dosage, after having been exhausted to one grain hardness. 
This procedure is repeated for different salt dosages to determine the 
exchange capacity of the resin bed for various predetermined salt dosages. 
After a period of use following a regeneration, the available exchange 
capacity of the resin bed is determined by subtracting the exchange 
capacity of the resin bed used since the last regeneration from the 
selected design capacity of the resin bed. The exchange capacity of the 
resin bed used since the last regeneration is determined by measuring the 
volume of water passing through the resin bed since the last regeneration 
and multiplying that volume by the hardness of the water. The salt dosage 
to be used during m the next regeneration cycle is determined by 
subtracting the salt dosage required to provide the available exchange 
capacity from the salt dosage required to provide the design exchange 
capacity. 
Apparatus in accordance with this invention utilizes a turbine water meter 
located in the soft water outlet line of the water softener to measure the 
water usage in gallons since the last regeneration. A micro-computer is 
provided which is programmed to receive an input from the water meter, an 
input of the grains of hardness of processed water, and to automatically 
make the necessary calculations to determine when to regenerate the resin 
bed and to determine the proper salt dosage in terms of water fill time to 
the brine tank prior to each regeneration. 
The regeneration of a resin bed of the water softener in accordance with 
the above method and apparatus fully restores the resin bed to its design 
capacity upon completion of each regeneration cycle. The amount of 
saturated brine in the brine tank prior to each regeneration is just 
enough to restore the resin bed to its design capacity.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
To assist in the understanding of the water softener regeneration control 
system of this invention, a schematic diagram of a water conditioning 
system of conventional construction as shown in FIG. 1 will be described. 
The system 10 is designed to soften water when it is delivered to a 
residence or business for use during what is typically called the "service 
cycle" of the system. Periodically the system 10 must be regenerated to 
restore its softening capability. The system 10 is regenerated by the use 
of a brine solution during a "regeneration cycle". The present invention 
is concerned with the control of the regeneration cycle. 
During a service cycle, raw or hard water is passed through an supply pipe 
12 to a control valve 14. The control valve 14 supplies the raw water 
through a pipe 16 to a tank 18 which contains a bed of ion exchange resin 
particles. The raw water passes through the bed of resin and is withdrawn 
from the tank 18 through an outlet pipe 20. The water withdrawn through 
the outlet pipe 20, which has been softened by contact with the ion 
exchange resin again passes through the control valve 14 to a service pipe 
22. 
When the ion exchange resin losses its capacity to effectively soften the 
water passing through it, regeneration is necessary. A regeneration cycle 
typically includes cycles to backwash and rinse the resin. Those cycles 
are followed by a brine cycle during which a brine solution flows through 
the ion exchange resin particles. A timer 24 initiates the brine cycle by 
actuating the control valve 14 to direct water from the supply pipe 12 
through a pipe 26 and aspirator valve 28 to pipe 30. The flow through pipe 
30, which passes through control valve 14, is directed by the control 
valve to outlet pipe 20. The water from pipe 26 passing through the 
aspirator valve 28 creates a pressure reduction by Venturi effect in a 
pipe 32 which extends to near the bottom of a brine tank 34. Due to the 
pressure reduction, brine is drawn from the brine tank 34 through the pipe 
32 and flows with the water through pipe 30, control valve 14, and pipe 20 
to the bottom of resin tank 18. The flow of brine through the ion exchange 
resin particles removes the hardness creating ions and carries them, with 
the discharge water, through pipe 16, control valve 14 to a drain 36. The 
flow of water through pipe 26 as controlled by timer 24 is continued long 
enough to withdraw all of the brine available to the pipe 32 in the brine 
tank 34. Thereafter the control valve 14, stops the flow of water to pipe 
26 from pipe 12, and instead directs it to outlet pipe 20 to backwash the 
ion exchange resin particles. Prior to the next regeneration cycle, water 
from the supply pipe 12 is directed by the control valve 14 to the brine 
tank 34 to create brine for the next regeneration cycle. In accordance 
with this invention, the softening system 10 also includes a 
microprocessor control 38 and a water meter 40. 
The present invention is directed to an improved method and apparatus for 
controlling the regeneration cycle, so as to provide improved efficiency 
in the use salt and water for regeneration, while at the same time 
insuring that softening capacity will not be lost between regeneration 
cycles. 
Referring to FIG. 2, a theoretical salt versus capacity curve for an ion 
exchange resin bed is shown. The amount of ion exchange resin in the resin 
tank will determine the maximum theoretical operating capacity of the 
softener. However, operating the softener at its maximum theoretical 
capacity point, results in relatively inefficient salt usage. If the 
softener is operated at lower points on the salt/capacity curve, the salt 
efficiency will increase. In accordance with method of this invention, the 
softener control is designed to force the softener to operate on the 
lower, more efficient portion of the salt/capacity curve. 
The volume of water flow through the resin tank 18 from the pipe 12 to the 
pipe 22 is measured by the water meter 40. The softening capacity used 
since the last regeneration is determined by multiplying the quantity of 
water used, as measured by the water meter 40, by the predetermined 
hardness of the hard water entering the resin bed through the pipe 12. 
Softening capacity is typically expressed in term of grains of hardness. 
The total softening capability of the system following a regeneration can 
be expressed in terms of grains of hardness, as can the amount of 
softening capacity which has been used since the last regeneration. 
Referring to FIG. 3, which is a capacity bar chart, terms used in setting 
forth the use of softening capacity of a softener in terms of its last 
regenerated capacity will be explained. Immediately following the 
regeneration of the resin bed, the full regenerated capacity is available 
as represented by 0% Exhausted on the left. As the softener is used to 
soften water, the used softening capacity is represented by the portion of 
the bar chart labeled "Capacity Used". The exhaustion of the softening 
capacity of the resin bed is indicated on the right of FIG. 3 by 100% 
Exhaustion. Thus, the portion of the bar chart to the right of the line 
identified by the letter "P" represents the remaining capacity. As 
indicated by the arrow at the top of FIG. 3, progress represented by the 
letter "P", is measured in terms of the portion of the capacity available 
after the last regeneration which has been used. 
One procedure which has been used for determining when the resin bed should 
be regenerated is based upon reserving a fixed amount, typically 30% of 
the total regenerated capacity. Thus, when use exceeds 70% of the total 
regenerated capacity, a regeneration is scheduled. 
Referring now to FIG. 4, added to the capacity bar chart of FIG. 3 are two 
additional values, one of which is a "threshold capacity" as indicated by 
the letter "T" and an "allocated capacity" as indicated by the letter "A". 
In accordance with the method of this invention, regeneration of a water 
softener resin bed is based upon comparing the percentage of capacity used 
to a range of capacity values, the lower limit of which is defined as a 
Threshold Capacity and the higher limit of which is defined as an 
Allocated Capacity. In a preferred embodiment of this invention, ten index 
levels, or ranges of capacity vales are established. The percentage of 
capacity used or "progress" is compared to one of the index levels. The 
threshold and allocated capacities are determined by the following 
formuli: 
T=N/(N+2) 
A=(N+1)/(N+2) 
Where: T=Threshold Capacity 
A=Allocated Capacity 
N=Index Level 
Using these formulas for establishing the threshold and allocated 
capacities, their percentage values for index levels 0 through 9 are shown 
in the chart of FIG. 5. 
In accordance with the method of this invention for controlling 
regeneration, if the progress since the last regeneration is less than the 
threshold capacity of the index level currently being used, no action with 
respect to initiating a regeneration will be taken, and the progress will 
be compared against the same index level for successive days as long as 
the progress does not exceed the threshold capacity. The progress will 
continue to be compared to the threshold and allocated capacities of the 
same index level on a daily basis, until the progress is greater than the 
threshold capacity. When the threshold capacity is exceeded, the next 
index level will be used for comparison with the progress on the next day. 
Since the threshold value for the index level 0 as shown in FIG. 5 is 0, 
should there be use of capacity on the first day, the method of this 
invention will be indexed to the first level. As the progress is compared 
on a daily basis with the current index level, should the threshold value 
be exceeded but not the allocated value, the progress comparison on the 
subsequent day will be at the next index level. However, if on any day the 
comparison shows the allocated capacity for the current index level to 
have been exceeded, a regeneration of the resin bed will be scheduled. In 
summary, in accordance with this method of controlling the scheduling of 
regeneration, the incrementing of the index level to the next level can 
only occur once per day, and if the index level is changed, it will only 
change at the time of day when a regeneration occurs if one is called for. 
FIG. 6 schematically represents the routine for scheduling a regeneration 
of the resin bed of a softener in accordance with one aspect of the method 
of this invention. That is, in accordance with this regeneration method 
(1), the comparison of progress to the threshold and allocated capacities 
for the index levels set forth in FIG. 5. With threshold and allocated 
values for index levels determined in accordance with the formula 
previously set forth, in accordance with this regeneration method 1, if 
progress as represented by the letter P is greater than allocated value as 
represented by the letter A, then the index level N is reset to 0 and a 
regeneration scheduled. If the progress is not greater than the allocated 
value and further is not greater than the threshold value, then a 
regeneration is not scheduled. However, if the progress is not greater 
than the allocated value but is greater than the threshold value, then the 
index level is advanced by 1. If the index level is not 10, the allocated 
and threshold values at the next index level are utilized for the 
following day's comparison. If the index level is equal to 10, it is reset 
to 9 for use in the next day's comparison. 
The method for controlling the regeneration of a water softener resin bed 
in accordance with this invention also takes into consideration the day of 
the week. As will be hereinafter described, if the previous method for 
determining whether or not a regeneration should be scheduled does not 
call for a regeneration, then a regeneration may be scheduled based upon a 
comparison with a historical day of the week usage. In accordance with 
this aspect of the method of this invention, at the beginning of each day, 
the current percent capacity used (progress) is stored as a reference 
value P.sub.R. At the end of each day, the current day's water usage (U) 
is calculated by subtracting the progress at the beginning of the day 
(P.sub.R) from the progress at the end of the day (P) as set forth in the 
following formula: 
EQU U=P-P.sub.R 
The historical daily capacity (H.sub.D) for the particular day of the week 
just completed is then updated according to the formula: 
EQU H.sub.D,new=(H.sub.D,old).times.(0.7)+(U).times.(0.3) 
A regeneration is scheduled if 150% of the historical daily usage for the 
next day of the week will be greater than the remaining capacity which may 
be expressed as: 
EQU (H.sub.D,next) (1.5)&gt;(100-P) 
FIG. 7 schematically represents the routine for scheduling a regeneration 
of the resin bed of a softener in accordance with another aspect of the 
method of this invention. That is, a comparison is made of the progress at 
the end of a day to the next calendar day historic usage. In accordance 
with this regeneration method (2), the usage during a day, as determined 
by subtracting the usage of the progress at the beginning of day from that 
at the end of the day is, used in accordance with the formula set forth 
above to establish a new historical daily usage for the just completed 
calendar day. One and one half times the historical usage for the upcoming 
calendar day is then compared to the remaining capacity of the softener. 
If one and one half times the historical usage for the next calendar day 
is greater than the remaining capacity, a regeneration is scheduled. If it 
is not greater, a regeneration is not scheduled. 
The method of this invention also involves a variable capacity calculation 
which is based upon a variable reserve and a variable salt dosage. For a 
particular water softener resin bed, five index capacities (I.sub.c) are 
established. For the initial regeneration of the resin bed, the middle or 
third out of 5 index levels is chosen. The variable capacity feature 
permits the regeneration of the softener to be adjusted to the water 
hardness and usage pattern of a particular installation. The decision to 
change the index capacity is based upon the following formula: 
EQU H.sub.n,new =(0.7) (H.sub.n,old)+(0.3) (N.sub.d) 
Where: 
H.sub.n =Historical number of days between regenerations 
N.sub.d =Number of days since a regeneration 
FIG. 8 schematically represents the routine for making the variable 
capacity adjustment in accordance with one aspect of the method of this 
invention. A new historic number of days between regenerations is 
calculated in accordance with the formula set forth above. If the new 
historic number of days between regenerations is less than two and the 
index capacity is less than five, the index capacity is increased by one. 
That is, if the index capacity were at the initialization level of three, 
it would be increased to four. If the new historic number of days is not 
less than two and the index capacity not less than five, but the historic 
number of days is greater than five and the index capacity greater than 
one, the index capacity is decreased by one. That is, if the index 
capacity were at the initialization value of three, it would be decreased 
to two. The newly determined index capacity is then utilized in still 
another step in the method of this invention, i.e., that of a salt and 
water adjustment. 
Assuming that there is enough salt available to create a saturated brine 
solution of any amount of water to be used as brine, the salt dosage may 
be adjusted by adjusting the amount of water utilized to form the 
saturated brine. At the time of regeneration, there will typically be, and 
in fact should be, in accordance with the method of this invention, 
softening capacity remaining. That is, the progress should always be less 
than 100% when a regeneration is scheduled. The remaining or residual 
capacity of the resin bed may be expressed in terms of the amount of salt 
(or saturated brine) required to provide the remaining or residual 
capacity in the resin bed. It being desirable to only use the amount of 
salt required to restore the softener to its original capacity, the 
residual or remaining capacity should be taken into account so as to 
reduce the amount of salt used. The residual salt content for a high 
percentage progress (that is, the resin bed approaching exhaustion) can be 
approximated as: 
SR=(100-P) / 100 * OPC / TCS 
Where: SR=Residual salt 
P=Progress to exhaustion (expressed in percentage) 
OPC=Operating capacity (in grains) 
TCS=Theoretical capacity of salt (5995 grains/lb) 
The adjusted salt dosage (SDA) is then determined by subtracting the 
residual salt (SR) from the operating salt dosage (OPS) which may be 
expressed as follows: 
EQU SDA=OPS-SR 
Referring to FIG. 9, a schematic representation of the routine implemented 
by a microprocessor for determining the salt dosage to be used for the 
next regeneration is set forth. If the progress since the last 
regeneration is less than 60%, the salt dosage to be used to restore the 
softener should be at the lowest level, or number 1. However, if the 
progress since the last regeneration is greater than 60%, but less than 
70%, the second salt dosage should be used. Similarly, if the progress is 
greater than 70% but less than 80%, the third salt dosage level should be 
used. If the salt dosage is greater than 80% but less than 90%, the fourth 
salt dosage level is used. Finally, if the progress since the last 
regeneration is greater than 90%, the fifth salt dosage level is used for 
the next regeneration. 
Referring to FIG. 10, a schematic representation of the overall routine for 
scheduling the occurrence and controlling the variables of a regeneration 
in accordance with all aspects of the method of this invention is set 
forth. 
As indicated in the schematic representation, the index capacity is set at 
3, the number of days between regeneration at 3 historical number of days 
at 3.56 and historic days usage at 15%. If it is the initial regeneration, 
the softener is merely regenerated and returned to service. The capacity 
used is measured and at the next scheduled regeneration time, a decision 
is made in accordance with the first aspect of this invention, as set 
forth in the schematic representation of FIG. 6, as to whether or not a 
regeneration should be scheduled. If a regeneration is not scheduled in 
accordance with the first aspect, the usage is then utilized in 
determining whether or not a regeneration should be scheduled in 
accordance with the second aspect. If a regeneration is scheduled in 
accordance with either aspect, the variable capacity adjustment, in 
accordance with the schematic representation of FIG. 8, is made so as to 
provide a salt and water adjustment, as set forth in the schematic of FIG. 
9. The resin bed is then regenerated and returned to service. If a 
decision is made not to regenerate in accordance with the second aspect of 
the method, one day is added to the number of days between regeneration 
for use in considering regeneration at the next scheduled time. 
It should be apparent to those skilled in the art, that while what has been 
described is considered at present to be a preferred embodiment of the 
method for regeneration of a water softener of this invention, in 
accordance with the patent statutes, changes may be made in the method 
without actually departing from the true spirit and scope of this 
invention. 
The appended claims are intended to cover all such changes and 
modifications which fall within the true spirit and scope of this 
invention.