Note: Descriptions are shown in the official language in which they were submitted.
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STATIC AND DYNAiVIIC TURBIDITY SENSING
IN A WASHING APPLIANCIE
BACKGROUND OF THE INVENTION
The use of turbidity sensors in dishwashing machines and clothes washing
machines is well known. The sensors typically measure; the amount of food,
soil
or dirt in the wash water, with the water being recirculated until a pre-
determined
level of soil has accumulated, after which the dirty water is drained.
"Smart" dishwashers have been developed which automatically determine
particular parameters to adjust the operation of the dishwasher. For example,
in
Applicant's U. S. patent 5,797,409, the presence of a rinse aid is detected by
measuring turbidity of the water after the rinse aid should have been
dispensed
and comparing the measured turbidity to a known turbi~dity for clear water
using a
turbidity sensor. If no rinse aid is detected, additional time is added to the
drying
cycle.
Similarly, U. S. Patent 5,331,177 discloses a "sanart" dishwasher which
utilizes turbidity caused only by detergent, so as to autamatically abort the
cycle
and save energy.
Dish and clothes washing appliances have two distinct operational states.
First, the washer has a static state in which no components are in motion that
2 0 cause disturbance within the wash water. Secondly, the washer has a
dynamic
state wherein one or more components are disturbing the wash water. A
turbidity
sensor is typically extremely sensitive to detergent in the wash water when
the
washer is in a dynamic state, and far less sensitive to detergent in the wash
water
when the washing machine is in a static state.
2 5 Accordingly, a primary objective of the present: invention is the use of a
turbidity sensor in a washing appliance to sense soil or dirt within the wash
water
when the washer is in a static state, and to sense detergent in the wash water
when
the washer is in a dynamic state.
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Another objective of the present invention is the provision of measuring
detergent and soil in wash water of a washing appliance so as to allow
adjustments
in the operational cycles of the appliance.
A further objective of the present invention is the provision of a method
for determining the presence of detergent and soil in wash watp;,r of a
clothes
washing machine or dishwasher, with the appliance automatically making
cyclical
adjustments in response to the presence or absence of detergent and/or soil in
the
water.
Another objective of the present invention is the; provision of a method for
l0 verifying that detergent has been properly dispensed in a dishwashing
machine or
clothes washing machine.
Another objective of the present invention is the provision of a method for
minimizing or eliminating detergent-induced spotting cm items in a dishwasher.
Another objective of the present invention is the provision of an improved
smart washing appliance which automatically responds to wash water turbidity
in
the static and dynamic states.
These and other objectives will become apparent from the following
description of the invention.
SUMMAIY OF THE INVENTION
2 0 A method is provided for measuring detergent and soil in wash water of a
dishwashing machine and clothes washing machine, wherein the soil is sensed or
measured during a static state and the detergent is sensed or measured during
a
dynamic state using a turbidity sensor. The detergent is sensed both before
and
after a detergent dispensing operation to determine that detergent is properly
2 5 dispensed. Lack of detergent identifies when a bulk detergent dispenser is
empty
or the dispenser is malfunctioning. Cycle decisions, such as the length of the
final
rinse, can be made based upon the detergent level in the wash water. Cycle
decisions can also be made based upon the sensing of the soil in the wash
water,
such as the need for a longer wash cycle.
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DETAILED DESCRIPTION OF THE INVENTION
Dishwashers and clothes washers have two distinct operational states that
exist during the operation of the appliance. The static state is one in which
no
components, such as pumps and heaters, are active, such that there is no
disturbance within the wash water. The dynamic state is one in which one or
more
components are active, and by their nature, cause a disturbance in the wash
water.
An analog turbidity sensor can be designed for two characteristics to occur.
First, the sensor is extremely sensitive to detergent in the wash water when
the
appliance is in a dynamic state. Second, the sensor is far less sensitive to
detergent in the wash water when the appliance is in the static state. These
characteristics allow the turbidity sensor to be used to sense soil within the
wash
water during the static state, and to sense detergent in the wash water when
the
appliance is in the dynamic state. Accordingly, turbidity measurements by the
turbidity sensor can be used to make automatic cycle decisions based upon
either
the soil or the detergent content of the wash water.
For example, during the prewash cycle of the machine, the soil content of
the water can be sensed and measured by the turbidity sensor, with the output
being used by a microprocessor in the machine to automatically adjust the wash
cycle to ensure adequate washing. As another example, the same turbidity
sensor
2 0 can be used to sense and measure the detergent content of the wash water
in the
final rinse cycle of the machine, with the microprocessor automatically
adjusting
the cycle to reduce or eliminate detergent. In a dishwasher, such sensing and
cycle adjustment will minimize detergent-induced spottiing on t:he dishes,
glasses
and silverware. If the sensed level of detergent is above a preset threshold
level,
2 5 an extra rinse cycle can be automatically added so as to eliminate the
detergent-
induced spotting.
The method of measuring or determining detergent in the wash water also
allows verification that detergent has been properly dispensed into the wash
water
of the clothes washing machine or dishwashing machine. More; particularly, the
3 0 turbidity of the water is measured both before and after the detergent
dispensing
CA 02421531 2003-03-10
operation to verify that the appropriate change in the turbidity sensor output
has
taken place. In a machine with a bulk detergent dispenser, this process can be
used to indicate that the dispenser has run out of detergent or is
malfunctioning.
As an alternative, the turbidity sensor can also be used during the dynamic
status to determine the presence of both soil and detergent in the wash water
and
generate an output signal to which the microprocessor can react to adjust the
operational cycles accordingly.
Thus, the method of determining the presence of detergent and soil in the
wash water, according to the present invention, allows various decisions to be
1 o made regarding the various washing cycles, so that alterations can be
automatically made to increase efficiency based upon signals from the
turbidity
sensor in both the static and dynamic states.
The invention has been shown and described above with the preferred
embodiments, and it is understood that many modifications, substitutions, and
additions may be made which are within the intended spirit and scope of the
invention. From the foregoing, it can be seen that the present invention
accomplishes at least all of its stated objectives.
