Dishwasher with dynamically controlled cycle of operation

Abstract

A method of controlling the operation of an automatic dishwasher having at least one cycle of operation and a sensor that indicates a degree of turbidity of liquid in the dishwasher includes repeatedly determining a correction value for the sensor related to the scaling of the sensor and executing a de-scaling cycle of operation based thereon.

What is claimed is: 
     
         1 . A method of controlling operation of a dishwasher having at least one cycle of operation and a sensor outputting a signal indicative of a degree of turbidity of liquid within the dishwasher, the method comprising:
 repeatedly determining a correction value for the sensor related to the scaling of the sensor;   determining a rate of change of the correction value based on the repeated determinations of the correction value; and   modifying the at least one cycle of operation based on the determined rate of change of the correction value.   
     
     
         2 . The method of  claim 1 , wherein modifying the at least one cycle of operation comprises at least one of adding a step of the at least one cycle of operation and eliminating a step of the at least one cycle of operation and altering a parameter of the at least one cycle of operation. 
     
     
         3 . The method of  claim 2 , wherein the at least one cycle of operation comprises a heated drying step and the eliminating the step comprises eliminating the heated drying step. 
     
     
         4 . The method of  claim 2 , wherein the at least one cycle of operation comprises a heated drying step and wherein altering the parameter comprises reducing the temperature of the heated drying step. 
     
     
         5 . The method of  claim 4 , wherein reducing the temperature of the heated drying step comprises performing a non-heating drying. 
     
     
         6 . The method of  claim 2 , wherein altering the parameter comprises performing a non-heating drying for an increased length of time. 
     
     
         7 . The method of  claim 2 , wherein altering the parameter comprises changing an amount or type of chemistry applied during the washing step. 
     
     
         8 . The method of  claim 2 , wherein altering the parameter of the at least one cycle of operation comprises changing an amount of a rinsing aid applied during a rinsing step. 
     
     
         9 . The method of  claim 1 , wherein modifying the at least one cycle of operation comprises performing at least one additional rinsing to a first rinsing. 
     
     
         10 . The method of  claim 9 , wherein the at least one additional rinsing comprises a reduced amount of rinse fluid compared to the first rinsing. 
     
     
         11 . The method of  claim 1 , further comprising comparing the determined rate of change to a threshold value and modifying the at least one cycle of operation if the determined rate of change satisfies the threshold value. 
     
     
         12 . The method of  claim 1 , wherein determining the rate of change of the correction value comprises at least one of:
 comparing each determined correction value to a predetermined threshold value over a predetermined number of cycles;   comparing each determined correction value to a previously determined correction value over a predetermined number of cycles;   determining a moving average of a predetermined number of the determined correction values and comparing the moving average to a previously determined threshold value; and   determining a moving average of a predetermined number of the determined correction values and comparing the moving average to a previously determined moving average.   
     
     
         13 . The method of  claim 1 , further comprising determining a water hardness based on the determined rate of change. 
     
     
         14 . The method of  claim 13 , wherein the water hardness is determined from a table lookup of water hardness and rate of change. 
     
     
         15 . The method of  claim 1 , further comprising comparing the determined rate of change to a threshold value and executing a de-scaling cycle if the determined rate of change satisfies the threshold value. 
     
     
         16 . The method of  claim 1 , wherein the sensor outputs a turbidity signal and is at least one of a turbidity sensor, a transmissive type optical sensor, a reflective type optical sensor, and a scattered type optical sensor. 
     
     
         17 . A method of controlling an operation of a dishwasher having at least one cycle of operation and a turbidity sensor outputting a turbidity signal indicative of a degree of turbidity of liquid within the dishwasher, the method comprising:
 repeatedly determining a correction value for the sensor related to the scaling of the sensor; and   modifying the at least one cycle of operation based on the determined correction value.   
     
     
         18 . The method of  claim 17 , wherein the at least one cycle of operation comprises a drying step and wherein modifying the at least one cycle of operation comprises at least one of: reducing the temperature of the drying step and performing a non-heating drying. 
     
     
         19 . The method of  claim 17 , wherein modifying the at least one cycle of operation comprises at least one of: performing at least one additional rinsing to a first rinsing and changing an amount of a rinsing aid applied during a rinsing step. 
     
     
         20 . The method of  claim 17 , further comprising determining a rate of change of the correction value; and
 modifying the at least one cycle of operation based on the determined rate of change.