Refrigerated case with anti-condensation control system

Abstract

A refrigerated case for storing food product includes a sensor module and a control module. The control module receives input from the sensor module and compares the input to a set point to generate an output indicative of a difference between the input and the set point, and further updates the output based on the input from the sensor module. A heater module controls a heater attached to a control surface of the refrigerated case based on the output to maintain a temperature of air adjacent the sensor module above a dew point temperature of room air.

1 . A refrigerated case for storing food product comprising: 
 a sensor module;    a control module receiving an input from said sensor module and operable to compare said input to a set point and generate an output indicative of a difference between said input and said set point, said control module updating said output based on said input from said sensor module; and    a heater modulator operable to control a heater attached to a control surface of the refrigerated case based on said output to maintain a temperature of air adjacent said sensor module above a dew point temperature of room air.    
   
   
       2 . The refrigerated case of  claim 1 , wherein said control module uses closed-loop control to control said heater.  
   
   
       3 . The refrigerated case of  claim 1 , wherein said sensor module includes a sensor mounted to a control surface selected from the group comprising a glass pane, a casing, a frame, a rail, or a wall of the refrigerated case.  
   
   
       4 . The refrigerated case of  claim 1 , wherein said sensor module includes a temperature sensor.  
   
   
       5 . The refrigerated case of  claim 1 , wherein said sensor module includes a relative humidity sensor.  
   
   
       6 . The refrigerated case of  claim 5 , wherein said sensor module includes a temperature sensor, said control module determining a dew point based on information received from said relative humidity sensor and said temperature sensor.  
   
   
       7 . The refrigerated case of  claim 1 , wherein said sensor module includes a dew point sensor.  
   
   
       8 . The refrigerated case of  claim 1 , wherein said control module includes a controller and at least one of an adder-subtractor and a limiter.  
   
   
       9 . The refrigerated case of  claim 1 , wherein said control module is in communication with a main controller.  
   
   
       10 . A bank of refrigerated cases for storing food product comprising: 
 a sensor module having a first sensor positioned adjacent a control surface of at least one of the refrigerated cases;    a control module receiving an input from said sensor module and operable to compare said input to a set point and generate an output indicative of a difference between said input and said set point, said control module updating said output based on said input from said sensor module; and    a heater modulator operable to control a heater attached to said control surface of said at least one of the refrigerated cases based on said output to maintain a temperature of air adjacent said first sensor above a dew point temperature of room air.    
   
   
       11 . The bank of refrigerated cases of  claim 10 , wherein said control module uses closed-loop control to control said heater.  
   
   
       12 . The bank of refrigerated cases of  claim 10 , further comprising a plurality of sensor modules respectively associated with each refrigerated case.  
   
   
       13 . The bank of refrigerated cases of  claim 10 , wherein said first sensor is a temperature sensor.  
   
   
       14 . The bank of refrigerated cases of  claim 10 , wherein said sensor module further includes a second sensor.  
   
   
       15 . The bank of refrigerated cases of  claim 14 , wherein said second sensor is a relative humidity sensor.  
   
   
       16 . The bank of refrigerated cases of  claim 15 , wherein said control module determines a dew point based on information received from said relative humidity sensor and said first sensor.  
   
   
       17 . The bank of refrigerated cases of  claim 16 , wherein said first sensor is a temperature sensor.  
   
   
       18 . The bank of refrigerated cases of  claim 10 , wherein said control surface is selected from the group comprising a glass pane, a casing, a frame, a rail, or a wall of said at least one of the refrigerated cases.  
   
   
       19 . The bank of refrigerated cases of  claim 10 , wherein said control module is in communication with a main controller.  
   
   
       20 . The bank of refrigerated cases of  claim 10 , wherein said first sensor is a dew point sensor.