Abstract:
Controlling internal humidity for a device by receiving an environmental parameter relating to a humidity control in the device, analyzing the environmental parameter to determine a humidity condition of the device, and sending a signal to activate a heater based on the humidity condition. A device including humidity control includes a humidity measuring arrangement, a temperature measuring arrangement, a processor receiving a humidity input from the humidity measuring arrangement and a temperature input from the temperature measuring arrangement, the processor comparing the humidity input and temperature input to stored data to determine a humidity condition of the device and a heater which is activated upon the determination of a predetermined humidity condition.

Description:
BACKGROUND 
       [0001]    Mobile units (MU) such as mobile computers are relied on for business and personal use in a wide variety of applications. Many of these devices are used in a variety of environments where rapid changes in temperature and humidity are common. High levels of humidity may develop internally in a mobile unit which reduces the product life cycle and reliability. 
         [0002]    Many mobile units also include optical devices. Optical devices include scanners and imagers. A rapid change in the temperature of the air within the housing of an optical device can cause condensation to build up on an optical window of the device, interfering with operation. In particular, condensation building up within the housing is a difficult problem to address. Some devices employ a chemical desiccant within the housing to remove moisture. However, chemical desiccants have a short lifetime and becomes useless when saturated. The desiccant must then be changed. Again, this is a difficult process because the desiccant is within the housing and users are generally discouraged from opening the housing because it may damage the device, void the warranty, etc. 
       SUMMARY OF THE INVENTION 
       [0003]    The present invention is related to a method for humidity control. The method comprises receiving an environmental parameter relating to a humidity control in a device, analyzing the environmental parameter to determine a humidity condition of the device, and sending a signal to activate a heater based on the humidity condition. 
         [0004]    In an exemplary embodiment of the present invention, a dual function heater within a terminal is created. One function is to warm internal components at low ambient temperatures while the other function is to remove internal humidity typically associated with higher ambient temperatures and humidity. Using hardware and/or software, the internal humidity of the mobile device may be monitored and the humidity may be dissipated using the heater. The hardware and/or software may also monitor the change of temperature and humidity and appropriately enable the heater to remove the humidity while minimizing the energy required to remove the humidity. 
     
     
       DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  illustrates an exemplary system of a humidity controller according to the present invention. 
           [0006]      FIG. 2  illustrates an exemplary circuit diagram of a heater control of a mobile unit according to the present invention. 
           [0007]      FIG. 3  illustrates an exemplary method of humidity control according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The exemplary embodiment of the present invention describes a system and method for a dynamic internal humidity control for a mobile device. However, those skilled in the art will understand that the exemplary humidity control may be implemented in any device, whether the device is mobile or stationary. The humidity control is performed by a humidity controller and its constituent parts. The controller and parts will be discussed in detail below. 
         [0009]      FIG. 1  illustrates an exemplary system  200  of a humidity controller  201  according to the present invention. The humidity controller  201  measures an actual amount of humidity and an ambient temperature (i.e., environmental parameters) during the use of the humidity controller  201  to predict and control humidity within the device. The humidity controller  201  maintains a preset atmospheric condition in order to prevent the humidity level to go beyond a certain predetermined value, thereby preventing any damage to the unit and increasing product life cycle and reliability. Also, the humidity controller  201  maintains a preset temperature in order to prevent any condensation build up (i.e., fogging) on any glass or clear surface that may be present on the unit. The glass surface may be, for example, a transparent window for a scanner or imager or a display screen for a computing device. It should be noted that the example of the glass surface is exemplary only and that the surface may just as easily be composed of transparent plastics (as is exhibited on many conventional technologies). 
         [0010]    In the present invention, the amount of humidity is measured using a humidity detector  202 . The humidity detector  202  may be, for example, a humidity or moisture meter. In a preferred embodiment of the present invention, the humidity detector  202  is placed within the unit. Placement of the humidity detector  202  within the unit allows a more direct, accurate measurement of internal humidity to assess any subsequent actions to be taken by the humidity controller  201 . 
         [0011]    The ambient temperature is measured using an ambient temperature detector  203 . The ambient temperature detector  203  may be, for example, a thermocouple, a resistance temperature detector (RTD), etc. In a preferred embodiment of the present invention, the ambient temperature detector  203  is placed on the periphery of the unit. Placement of the ambient temperature detector  203  on the periphery of the unit allows a more direct, accurate measurement of ambient temperature to assess any subsequent measures to be taken by the humidity controller  201 . It should be noted that a second, internal temperature detector may also be included in the present invention. The second, internal temperature detector may be used to measure the temperature within a unit. This second measurement of temperature may be used by the humidity controller to further determine the amount of control to be exerted by the humidity controller  201 . 
         [0012]    Both the humidity detector  202  and the ambient temperature detector  203  provide input to a processor  204 . The processor  204  includes the logic for determining when and by how much the unit will control the conditions of the humidity controller  201 . As will be described in detail below, the processor  204  may be used in conjunction with a heater control  207  to control humidity within the housing of a device. In an alternative embodiment, the processor  204  may be used to directly control a heater  208  to control humidity within the housing, i.e., the heater control  207  may be eliminated. In a further exemplary embodiment, the processor  204  may not be used. For example, an additional hardware circuit, chop (e.g., an ASIC), or specialized computing device may be used to perform the functions described herein for the processor  204 . Thus, those skilled in the art will understand that while the exemplary embodiment is described with reference to a processor  204  and a heater control  207 , it is possible to implement the present invention without these specific components. 
         [0013]    In the exemplary embodiment, the processor may contain a memory  205  and an input/output component  206 . The memory  205  may be used, for example, to store previously measured data by the humidity detector  202  and the ambient temperature detector  203 . The memory may be a separate component outside the processor itself, e.g., hard drive, flash memory, ROM, etc. The input/output component  206  may be used, for example, to send any signals that the processor  204  generates or the received input to subsequent units involved with the dynamic humidity control. It should be noted that there may be further components connected to the processor  204  of the humidity controller  201 . For example, a display mechanism may be used to indicate to a user that a component of the humidity controller  201  has been activated. The display mechanism may be, for example, a light emitting diode (LED), a speaker, or a digital display. 
         [0014]    In order to accomplish the humidity control, a heater  208  is utilized. A heater control  207  is used to adjust the heater  208  operation by receiving signals from the input/output components  206  of the processor  204 . The use of the heater  208  allows the humidity controller  201  to control the amount of humidity to be present within the unit and the temperature of any glass surface prone to condensation buildup. For example, if the ambient temperature reaches very low values, then the heater  208  may be activated to raise the temperature of the unit to a sufficient amount to prevent both high levels of humidity building up within the unit and condensation from forming on any glass surfaces. 
         [0015]    For example, when it is very cold, the heater  208  may be used to warm the components within the device. However, when the ambient temperature is higher, it may also be advantageous to turn on the heater to prevent moisture build-up, condensation, fogging, etc., within the device. Thus, the processor  204  may store data in the memory  205  indicating certain environmental factors. In one example, the memory  205  stores dew point temperatures for various ambient humidity levels. Thus, the processor  204  receives the humidity detector  202  input and determines the dew point temperature based on the data stored in memory  205 . The processor  204  also receives the ambient temperature input from ambient temperature detector  203 . If the processor determines that the ambient temperature trend is dropping toward the dew point, the processor  204  may send an output signal to the heater control  207  to turn the heater  208  on to prevent the dew point from being reached inside the device, thereby preventing condensation, fogging, etc. and also minimizing the amount of energy required to maintain humidity conditions. 
         [0016]    The above example shows that the humidity controller  201  may be used to preemptively stop humidity issues by predicting trends or other changes in environmental conditions. It also shows that the heater  208  is not limited to low temperature operation. For example, in high humidity locations, the temperature may be fairly high (e.g., 60° F.), but the heater  208  may be used to prevent the temperature inside the device from dropping a few degrees (even at the high temperature) to prevent condensation from occurring. 
         [0017]      FIG. 2  illustrates an exemplary circuit diagram of a heater control (e.g., heater control  207 ) of a mobile unit implementing the humidity control according to the present invention. The following will describe the components and functionality that may be used to implement the exemplary embodiment of the heater control  207 . It will not describe every component since those skilled in the art will understand the purpose and functionality of the components used to control the heater  208 . 
         [0018]    Initially, the heater control  207  includes a component U 30  which is, for example, a MAX6510CAUT-T that is a resistor-programmable SOT (small outline transistor) temperature switch sold by Maxim Integrated Products. The component U 30  operates as a thermostat to enable the heater  208 . Thus, the output of pin  3  is used to control the heater  208 . Those skilled in the art will understand that the output of pin  3  and the components which are downstream of the output enable/disable the heater  208  which is connected to heater control  207  via heater connection CN 15 . 
         [0019]    The resistor R 208  may be used to set a set point for heater operation. For example, the resistor R 208  may set a set point for low temperature heater operation (e.g., if temperature is below 0° C., turn on heater). However, the resistor R 534  allows the terminal to incorporate multiple temperature values to turn on the heater  208 . The resistor R 534  in conjunction with MOSFET Q 66  allows the processor  204  to enable the heater  208  at a high temperature typically set when high humidity is expected. As described above, the heater  208  may be used at higher temperature than expected for heater operation because the heater  208  is being used for both heating of components at low temperatures, but also for humidity control at higher temperatures. The resistor R 534  may be, for example, a discrete resistor. However, it should be noted that the resistor R 534  being a discrete resistor is exemplary only and that other resistor types may be used. For example, the resistor R 534  may be a variable or processor controlled resistor which would allow a dynamic enablement of the heater as different ambient conditions exist. 
         [0020]    It should be noted that the use of the thermostat component U 30  is exemplary only and that the present invention may be implemented without the use of that component. For example, the processor  204  may directly enable and disable the heater  208  as a result of the processor  204  directly monitoring the humidity detector  202  and the ambient temperature detector  203 . 
         [0021]      FIG. 3  illustrates an exemplary method  400  of humidity control according to the present invention. Initially, in step  401 , the humidity controller  201  is activated. The humidity controller  201  may be activated personally by the user or it may be automatically activated upon activation of the mobile unit. The humidity controller  201  may also be activated using a sensor that determines if the humidity controller  201  should be activated. The sensor would be connected to a processor of the mobile unit that sends a signal to the humidity controller  201 . 
         [0022]    In step  402 , the humidity and ambient temperature are measured. As discussed above, the humidity detector  202  and the ambient temperature detector  203  perform these measurements, respectively. The measurements performed may be taken dynamically throughout the use of the mobile unit. For example, the measurements may be taken continuously to ensure that the mobile unit functions efficiently without any hindrance due to a gap in measurements. The measurements may be taken based on a timer to be performed every preset time period (e.g., 10 seconds, 30 seconds, 1 minute, 5 minutes). The measurements may also be taken upon based on a change in atmosphere conditions. This change may be detected, for example, by the sensor discussed above. 
         [0023]    The measured values are fed to the processor  204  and, in step  403 , the method  400  determines if the conditions are acceptable. As discussed above, the acceptable conditions may be preset during the manufacturing of the mobile unit. The acceptable conditions may also be ascertained by using a simple algorithm that incorporates different factors such as operating temperatures of components of the mobile unit, consequences of the operation of components of the mobile unit, and resultant internal temperature. 
         [0024]    If the measurements are found to be acceptable conditions for the mobile unit, then the method  400  returns to step  402  where a continuous process is created to dynamically control the humidity level in and around the mobile unit. It should be noted that subsequent measurements may be taken based on the above mentioned methods. 
         [0025]    If, however, the measurements are found to be unacceptable conditions for the mobile unit, then the method  400  proceeds to step  404  where the processor  204  determines the amount of control necessary to counterbalance the unacceptable conditions. Once the processor  204  makes such a determination, the input/output component  206  sends a signal to the heater control  207 . Upon sending this signal, in step  405 , the heater is activated. The method  400  then returns to step  402  to create the continuous process discussed above. 
         [0026]    It will be apparent to those skilled in the art that various modifications may be made in the present invention, without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.