Methods and apparatus for optimizing environmental humidity

Abstract

A humidity control apparatus and methods for use with, e.g., an environmental test chamber. In one embodiment, the apparatus comprises a system having a test chamber, a water tank, motive source for a gaseous humidity carrier, and temperature controllers for the tank and chamber. The carrier gas (e.g., air) is diffused through the water tank, thereby saturating the gas to a prescribed humidity level. This saturated gas is then passed into the chamber, and the environment within the chamber (i.e., humidity and temperature) controlled by the controller(s) so as to maintain the desired humidity level. The apparatus disclosed has the primary advantage of reducing or even substantially eliminating condensation within the test chamber when humidity levels are increased.

1 . Humidity control apparatus, comprising: 
 a water tank comprising a first temperature controller;    a test chamber;    a compressor operatively coupled between said water tank and said test chamber; and    an aerator, said aerator being operatively coupled to said compressor and located at least partly within said water tank;    wherein said compressor, tank, and controller cooperate to maintain a desired humidity level within said chamber without forming significant amounts of condensation therein.    
   
   
       2 . The humidity control apparatus of  claim 1 , further comprising a chamber temperature controller, said chamber temperature controller controlling chamber temperature according to the method comprising: 
 determining the allowable operating range of at least one of said chamber temperature controller and test chamber;    determining the allowable operating range associated with an object disposed within said test chamber; and    calculating a control setpoint based at least in part on said allowable operating ranges of said at least one of chamber temperature controller and test chamber, and on said object.    
   
   
       3 . The humidity control apparatus of  claim 2 , further comprising providing data related to the temperature of said object; and 
 wherein said act of determining the allowable operating range associated with an object disposed within said test chamber is based at least in part on said data.    
   
   
       4 . The humidity control apparatus of  claim 1 , further comprising a test chamber temperature controller comprising a temperature control algorithm providing input thereto, and said chamber controller controls temperature of an object within said test chamber according to the method comprising: 
 providing data related to the internal temperature of said object to said algorithm;    determining the allowable operating range associated with said object based at least in part on said data;    evaluating whether a valid control setpoint can be calculated based at least in part on said allowable operating ranges of at least one of said chamber temperature controller and said test chamber, and said object; and    calculating said valid control setpoint.    
   
   
       5 . The humidity control apparatus of  claim 1 , further comprising: 
 a first temperature probe adapted to generate first signals related to the temperature of a device under test (DUT);    a second temperature probe adapted to generate second signals related to the temperature of at least a portion of said test chamber; and    a chamber temperature control apparatus comprising:    a controller, operatively coupled to said test chamber and said probes and having an algorithm associated therewith.    
   
   
       6 . The humidity control apparatus of  claim 5 , wherein said algorithm is adapted to control the temperature of said chamber based at least in part on said first and second signals; 
 wherein said controller is further adapted to control the temperature of said chamber by: (i) establishing a first temperature for at least a portion of said chamber; (ii) identifying at least one change in said DUT thereafter; (iii) identifying at least one stabilization event in said DUT thereafter; and (iv) adjusting the temperature of said conditioning device based at least in part on said first and second signals and said acts of identifying.    
   
   
       7 . The humidity control apparatus of  claim 1 , further comprising temperature control apparatus operatively coupled to said chamber and adapted to control the temperature of at least a portion thereof based at least in part on the observance of a temperature stabilization event in a device under test (DUT) disposed within said chamber.  
   
   
       8 . The humidity control apparatus of  claim 1 , wherein said cooperation to maintain a desired humidity level within said chamber without forming significant amounts of condensation therein comprises delivering the humidified air at a temperature and saturation level that can be supported by an environment within said chamber, thereby significantly eliminating the accumulation of liquid water within the chamber.  
   
   
       9 . The humidity control apparatus of  claim 1 , wherein condensation is controlled such that it can only substantially occur in said water tank existing outside of the test chamber, thus preventing the condensation of water vapor within the chamber used for conditioning or evaluating the DUT.  
   
   
       10 . The humidity control apparatus of  claim 1 , wherein said compressor compresses a carrier gas and a carrier gas supply, said supply comprising a re-circulating system with a separate environment that is used to control humidity level.  
   
   
       11 . The humidity control apparatus of  claim 10 , wherein said carrier gas comprises air.  
   
   
       12 . A method of controlling the humidity within a closed chamber without substantial condensation, comprising: 
 providing a desired humidity level for said chamber;    sensing the actual humidity level within said chamber;    determining whether an increase or decrease in humidity within said chamber is required based at least in part on comparison of said desired and actual levels; and    if the humidity level needs to be decreased, performing at least one of (i) a dry purge process; or (ii) lowering the temperature of a volume from which humid gas is supplied to said chamber, thereby causing any condensation to selectively occur within said volume as opposed to said chamber.    
   
   
       13 . The method of  claim 12 , wherein said act of providing a humidity level comprises providing a humidity level which varies as a function of time according to a profile.  
   
   
       14 . The method of  claim 12 , wherein said act of performing a dry purge process comprises using a cryogenic purging apparatus.  
   
   
       15 . The method of  claim 12 , wherein said act of performing a dry purge process comprises using a desiccant cylinder process.  
   
   
       16 . The method of  claim 12 , wherein said act of performing at least one of (i) a dry purge process; or (ii) lowering the temperature of a volume from which humid gas is supplied to said chamber, comprises selectively performing both said dry purge process and lowering the temperature of a volume from which humid gas is supplied.  
   
   
       17 . A water supply apparatus for use in an environmental conditioning or test system, comprising: 
 a water tank adapted to contain water therein;    a level control system for maintaining a substantially constant level within said tank;    an aerator adapted to diffuse a carrier gas through the water of said tank, thereby raising the humidity level of the carrier gas output by said apparatus by a prescribed amount and in a predictable fashion; and    a temperature control system to control the tank and water temperature to selectively cause condensation to occur within the tank, as opposed to said conditioning or test system.    
   
   
       18 . The apparatus of  claim 17 , wherein said environmental conditioning or test system comprises: 
 a test chamber; and    a compressor operatively coupled between said water tank and said test chamber.    
   
   
       19 . The apparatus of  claim 18 , wherein said environmental conditioning or test system further comprises a chamber temperature controller, said chamber temperature controller controlling chamber temperature according to the method comprising: 
 determining the allowable operating range of at least one of said chamber temperature controller and said test chamber;    determining the allowable operating range associated with an object disposed within said test chamber; and    calculating a control setpoint based at least in part on said allowable operating ranges of said at least one of chamber temperature controller and test chamber, and on said object.    
   
   
       20 . The apparatus of  claim 19 , further comprising providing data related to the temperature of said object; and 
 wherein said act of determining the allowable operating range associated with an object disposed within said test chamber is based at least in part on said data.    
   
   
       21 . The apparatus of  claim 18 , further comprising a test chamber temperature controller comprising a temperature control algorithm providing input thereto, and said chamber controller controls temperature of an object within said test chamber according to the method comprising: 
 providing data related to the internal temperature of said object to said algorithm;    determining the allowable operating range associated with said object based at least in part on said data;    evaluating whether a valid control setpoint can be calculated based at least in part on said allowable operating ranges of at least one of said chamber temperature controller and said test chamber, and said object; and    calculating said valid control setpoint.    
   
   
       22 . The humidity control apparatus of  claim 18 , further comprising: 
 a first temperature probe adapted to generate first signals related to the temperature of a device under test (DUT);    a second temperature probe adapted to generate second signals related to the temperature of at least a portion of said test chamber; and    a chamber temperature control apparatus comprising:    a controller, operatively coupled to said test chamber and said probes and having an algorithm associated therewith.    
   
   
       23 . The humidity control apparatus of  claim 22 , wherein said algorithm is adapted to control the temperature of said chamber based at least in part on said first and second signals; 
 wherein said chamber controller is further adapted to control the temperature of said chamber by: (i) establishing a first temperature for at least a portion of said chamber; (ii) identifying at least one change in said DUT thereafter; (iii) identifying at least one stabilization event in said DUT thereafter; and (iv) adjusting the temperature of said conditioning device based at least in part on said first and second signals and said acts of identifying.    
   
   
       24 . The humidity control apparatus of  claim 18 , further comprising chamber temperature control apparatus operatively coupled to said chamber and adapted to control the temperature of at least a portion thereof based at least in part on the observance of a temperature stabilization event in a device under test (DUT) disposed within said chamber.  
   
   
       25 . A controller architecture for use in an environmental conditioning or testing system, comprising: 
 a first temperature controller operatively coupled to a test chamber of said system, said first controller being adapted to algorithmically control the temperature of at least a device under test (DUT) disposed within said chamber; and    a second temperature controller substantially independent temperature controller operatively coupled to a humidity-control water tank of said system;    
   
   
       26 . The architecture of  claim 25 , further comprising a humidity sensor adapted for sensing at least a portion of the interior volume of the test chamber; 
 wherein said humidity sensor is in operative communication with said first and second controllers to provide signals thereto, said signals being used by said controllers at least in order to maintain prescribed conditions of humidity and temperature within the chamber.    
   
   
       27 . The architecture of  claim 25 , further comprising a tank level sensing apparatus operatively coupled to at least one of said first and second controllers, said sensing apparatus adapted to generate a signal relating to the level within said tank, said level relating at least in part to the amount of interaction between water in said tank and a gas diffused therein.  
   
   
       28 . The architecture of  claim 27 , further comprising a pump operation and speed control apparatus, said control apparatus being operatively coupled to at least one of said first and second controllers and adapted to control at least one of said pump energization and pump speed.